There is several methods for removing calcium sulfate scale deposits from surfaces.
1, Strong concentrations of alkali metal hydroxides, such as sodium hydroxide or potassium hydroxide, shall be used to effect prolonged contact with the scale deposits so that the latter can be converted to calcium hydroxide The caustic solution must be continuously circulated over the scale encrusted surface and the reaction is frequently not complete because of the occluding nature of the hydroxide conversion product. This secondary insoluble calcium hydroxide product must be subsequently contacted with hydrochloric acid in order to produce water soluble calcium chloride which may then be removed by dissolving it in an aqueous solution.
2, Calcium sulfate scale deposits have also been removed by utilizing ammonium bicarbonate. However, as with strong caustic solutions, the ammonium bicarbonate converts the sulfate scale into another insoluble product, calcium carbonate. The latter must subsequently be contacted with an acid, such as hydrochloric acid, before it can be removed by dissolving in water. The rate at which the ammonium bicarbonate converts the calcium sulfate scale decreases in ratio to the amount of conversion product because of the occlusion which occurs on the scale surface. Accordingly, removal of the scale deposits is frequently incomplete and the efficiency of this method cannot be appreciably increased even if the ammonium bicarbonate solution is continually recalculated over the scale encrusted surface.
3, Another method presently known in the prior art for removing calcium sulfate scale deposits involves the use of solutions of alkaline chelating or sequestering agents such as ethylenediamine tetraacetic acid (EDTA), its tetrasodium salt, and nitrilo triacetic acid trisodium salt. These solutions are maintained at substantially higher than ambient temperature and must remain in contact with the scale for extended periods of time. However, the chelation or dissolution of the scale is generally slow.
The removal of calcium sulfate scale deposits by utilizing only a chelating agent, such as EDTA (ethylenediamine tetraacetic acid), is normally a rather slow procedure since the EDTA attacks the deposits very slowly. However, the rate of this reaction can be greatly increased by combining the EDTA with a carbonate, such as sodium bicarbonate, thereby increasing the rate of calcium sulfate dissolution to nearly twice that with EDTA alone. The mechanism of this reaction can be described as follows:
The carbon dioxide released by this reaction causes the scale deposits to break apart and thereby expose additional deposit surfaces which are more readily attacked by the EDTA.
It has now been discovered that the addition of particular surfactants i.e., fluorocarbon surfactants, to the EDTA-carbonate solvent solution serves to impart a rate of sulfate deposit dissolution that is substantially greater than the rate presently achievable with either EDTA by itself or EDTA in combination with a carbonate, with or without other surfactants.
Fluorocarbon surfactants, i.e., surfactants containing fluorocarbon radicals, in general have been found to be effective for use in the invention, with anionic fluorocarbon surfactants providing the greatest improvement in the extent and rate of sulfate deposit dissolution
4, An aqueous solution of an amino polyacetic acid and a carbonate, such as ammonium carbonate, ammonium bicarbonate, sodium carbonate, sodium bicarbonate, potassium carbonate and potassium bicarbonate, provides a more efficient calcium sulfate scale removal composition. It is thought that the aminopolyacetic acid reacts with the calcium ions in solution and forms a chelated species. This causes more calcium sulfate to dissolve, and also results in the release of hydrogen ion from the calcium polyacetic acid chelate. This released hydrogen ion reacts with the bicarbonate forming CO2 gas, which then aids in the scale break-up. In addition, surface active agents have been employed in such compositions,
The removal of calcium sulfate scale deposits from surfaces by contacting the deposits with an aqueous solution comprising a chelating or sequestering agent in the form of a polyamino carboxylic acid, a soluble carbonate or bicarbonate and a fluorocarbon surfactant. The solution is permitted to contact and react with the deposits at a pH of approximately 6 to 10 and at ambient or higher temperatures, depending upon the sufficiency of the reaction rate. The concentration of the polyamino carboxylic acid can be from a minimum of 1% to maximum solubility, the concentration of the carbonate is based upon the concentration of the polyamino carboxylic acid and maybe on the order of one mole of carbonate to one mole of acid, and the concentration of the fluorocarbon surfactant can be 0.002 weight percent or above.
The soluble carbonate may include any soluble carbonate or bicarbonate, such as (NH4)HCO3, NaHCO3, KHCO3, Na2 CO3, (NH4)2 CO3, K2 CO3 and mixtures thereof.
The chelating agent may be any suitable polyamino carboxylic acid such as EDTA, NTA (nitrilo triacetic acid), DTPA (diethylenetriamine pentaacetic acid), HEDTA (N-hydroxyethylethylenediamine triacetic acid), and mixtures thereof.
The concentration of the fluorocarbon surfactant in the overall composition can be a minimum of approximately 0.002 weight percent. The preferred concentration is between approximately 0.005 and 0.01weight percent. The optimum pH of the composition is between approximately 6 and 10.
The dissolution of the sulfate scale deposits can be achieved at a temperature of ambient or above, depending upon the reaction desired and the nature of the surface being cleaned. Higher temperatures may be utilized to increase the reaction rate,
Tuesday, August 16, 2011
Sunday, October 17, 2010
Ammoniated Citric Acid
Use of ammoniated citric acid for the chemical cleaning of high pressure boilers
Pre-commissional passivation
Before a boiler is put into service, it is customary to follow a "pre-commissional" chemical cleaning procedure. A newly constructed boiler will be contaminated by particulate debris, oils and greases, and rust. These are all removed in a sequence of steps, both chemical and mechanical. The resulting surface is chemically passivated to form a semi-conductive iron oxide film or layer of Fe2O3.
The Fe2O3 is a poor conductor of ions, (e.g. Fe2+ , Fe3+ ) therefore protecting the steel from further corrosion.
The passivating iron III oxide is not a permanent addition to the steel. It is easily removed if water in the boiler is acidic or contains chlorides.
It is also extremely thin ( 40 -100 A). In fact, when viewing the grey colour of a passivated boiler surface, we are really seeing the true colour of the steel itself.
The mechanism of passivation is thought to be as follows:
Following chemical cleaning itself, the surface is that of the steel itself, with no other layers. It can therefore quickly rust in the presence of water and oxygen. The boiler is filled with a dilute citric acid solution, which dissolves this rust. The pH is raised to an alkaline value using ammonia, and the sequestered iron remains in solution. Dissolution of iron on the surface stops and an oxidizing agent is added. This has the effect of impressing a positive surface potential on the steel. In other words, it initiates oxidation of the surface to iron oxide by withdrawing electrons.
As the potential increases, so does the oxidation, shown by the increase in the corrosion current. When the potential reaches about 0.6V for steel, the oxidation takes place as the formation of a semi-conductive layer of iron oxide. This layer can conduct electrons but not ions. Without a flow of ions, the steel cannot corrode and therefore the corrosion current decreases to the so-called passive current.
If the potential is further increased, the corrosion current remains constant until a point when the semi-conductive layer becomes transpassive, and ionic species are conducted through it. The corrosion current will again rise and passivity is lost. For iron the value of this potential is about 1.6V.
This means that by introducing an oxidizing agent to the ammonium citrate solution, which can impose a potential of between 0.6V and 1.6V on the steel surface, passivation will occur. After allowing time for the reaction, rapid draining of the solution removes the electrolyte and the steel is left in a temporarily passive state. A good choice of oxidizing agent is sodium nitrite, although sodium bromate or hydrogen peroxide can be used.
In-service conditions
If filled quickly with correctly treated water, and put into immediate service, the clean boiler will be operating at maximum efficiency and will have a basic passive layer intact.
Assuming good maintenance of the water supply, the boiler will operate for several years without further cleaning.
During operation, the boiler is fed by de-aerated, de-mineralized water containing additives. These basically scavenge for oxygen and control the pH of the feed.
By almost eliminating dissolved oxygen, while controlling pH and not overdosing additives, the boiler is kept in an optimum condition for steam production.
The choice of additives to boilers is based on many years of research. The object is always to minimize non-mobile deposits and corrosion, both of which can lead to failure.
When boilers are fired up after cleaning and adding treatment compounds, a reaction occurs between the surface of the boiler and the water. Another form of iron oxide is formed. This is magnetite, or Fe3O4 , which is black in colour.
Its formation is a complex process and can be summed up as follows:
The temporary iron oxide film, only a few angstrom thick, will break down.
A series of reactions occur between the iron and the water which result in the following two to form magnetite:
3Fe(OH)2 ---> Fe3O4 + H2 + 2H2 O and
3Fe + 4 H2 O ---> Fe3O4 + 4H2
Some intermediate reactions also produce hydrogen ions.
These lower the pH of the water during start up of boilers and have to be adjusted for with additives under monitoring. Care must be taken to monitor boiler conditions. Overdosing to raise pH too much will accelerate magnetite production by removing hydrogen ions too quickly. This film will be less dense and weaker.
However, if the pH is allowed to drop too far, the film is pickled away. The magnetite will continually be formed at an ever decreasing rate. Its formation can be monitored by analysing for free hydrogen. After a period of between 25000 and 40000 hours use, the magnetite film will be too thick and will require removing by chemical cleaning.
It may be that during the wildly fluctuating conditions during start-up that dosage of oxygen scavengers, such as hydrazine, is too high. The excess will dissociate to form ammonia. This will react with copper in condenser components to form the soluble species Cu(NH3)42+.
Cu + 4NH3 + 1/2 O2 + H2O ---> Cu(NH3)42+ + 2OH-
This reacts on return to the boiler as follows:
Cu(NH3)42+ + Fe ---> Cu + Fe2+ + 4NH3
This is undesirable since the ammonia is recycled for further damage, while the copper corrodes the boiler. Tube scale analysis may reveal metallic copper under magnetite, with copper I oxide mixed in the magnetite in small quantities. This copper, and its oxide must be removed during cleaning, together with the magnetite.
Chemical cleaning of the boiler
We have seen how a new, clean boiler can accumulate copper and magnetite which requires removal. There is a method we propose to do this. Using ammoniated citric acid and an oxidizing agent such as sodium nitrite or bromate, we will now show how this can be achieved.
1.Citric acid and ammoniated citric acid
Citric acid is a weak, tri-basic, organic acid. It forms complexes with ironII, IronIII and CuII ions which are stable in solution over a wide pH range.
When a citric acid solution is made up to a concentration of 3 to5 %, its pH is between 2 and 3, i.e. it is only weakly dissociated.
The process requires that the solution is partially neutralised to pH 4 using ammonia. This solution will, if heated to about 75 deg. C, dissolve ironIII oxide and magnetite, keeping both iron II and iron III in solution as complexes.
As long as the citric concentration remains at least 3 times the dissolved iron concentration, the iron will not precipitate out as hydroxide if the solution is further treated to pH 9.5 with extra addition of ammonia.
Once alkaline, an oxidizing agent is added to oxidize copper and allow it too to complex with the ammoniated citric acid:
BrO3 - +3Cu +12 NH3 +3H2O ---> Br- + 3Cu(NH3)4 2+ +6OH-
or 2NO2 - +2Cu + 2H2O +8NH3 ---> N2O2 2- + 2 Cu(NH3)4 2+ + 4 OH-
For excessive amounts of copper deposits, bromate is preferred to nitrite.
A separate passivation step is unnecessary, as we have seen earlier, with the reformation of the semi-conductive iron oxide film by reaction between the steel and the oxidizing agent.
For example, with bromate:
BrO3 - + 2 Fe ----> Br - + Fe2O3
2. Multi-stage cleaning, with initial alkaline boil-out, followed by further stages involving citric acid, ammonium bifluoride, ammonia, a corrosion inhibitor and an oxidizing agent.
After several years in service, a boiler will have scale deposits more complex than elemental copper, copper I oxide and magnetite.
Typically, minerals such as serpentine (3MgO.2SiO2.H2O), pectolite (Na2O.4CaO.6SiO2.H2O) and magnesium phosphate (Mg3(PO4)2 ) will be present.
It is therefore the job of chemical cleaning to remove all of these and revert the boiler to a (nearly) new condition.
It is worth mentioning again that boiler water treatment is aimed at inhibiting development of tube scaling, modifying deposits so they are easy to remove and removing oxygen from the water. Under high operating temperatures, very tiny amounts of impurities in the boiler water will form insoluble compounds.
As time progresses, these accumulate to the extent that the transfer of heat to the boiler water is impeded. Initially this is seen as an increased fuel bill, and later as failed tubes due to localized overheating.
This shows that while controlled boiler water treatment is essential, the time will come when the complete removal of accumulated scale is required to "rejuvenate" the boiler.
Initial alkaline boil-out.
Although usually applied to pre-commissional chemical cleaning of new boilers for the removal of oil and grease, there is evidence, based on laboratory work and from practical experience, that a primary phase of cleaning using alkaline chemicals loosens the bond between scale and metal. The choice of alkaline compounds is wide, but to avoid the possibility of stress corrosion cracking, simple sodium hydroxide is avoided. Other salts produce hydroxyl and other useful ions without excessively high pH , for example:
Na2SiO3 <=> 2Na+ + SiO32- Sodium Metasilicate
SiO32- + 2H2O <=> 2OH- + SiO2.H2O
Na2CO3 => 2Na+ + CO32- Sodium Carbonate
CO32- + H2O <=> OH- + HCO3-
Na3PO4 => 3Na+ + PO43- Trisodium Phosphate
PO43- + 3H2O <=> 3OH- + H3PO4
At atmospheric pressures, using external equipment, a solution of trisodium phosphate with a non-ionic wetting agent is a useful alkaline cleaning solution.
The mixing of trisodium phosphate with sodium metasilicate and a wetting agent has several additional advantages.
Phosphate attacks calcium carbonate, releasing carbon dioxide as an effervescing gas, which also loosens other scale:
3PO43- + 5CaCO3 + 5H2O ---> Ca5(OH)(PO4)3 + 10 OH- + 5CO2
Silicate is able to attack magnesium sludge :
Mg3(PO4)2 . Mg(OH)2 + 4SiO32- ---> 4MgSiO3 + 2PO43- + 2OH-
Under other circumstances, where calcium sulphate and/or calcium silicate are present, raising the pH using sodium hydroxide can be beneficial to the cleaning:
3PO43- + 5CaSO4 + OH- ---> Ca5(OH)(PO4)3 + 5SO42- and
CaSiO3 + 2OH- ---> Ca2+ + SiO44- + H2O
The overall effect of such an alkaline cleaning step is to loosen or transform the scale to make it yield more easily when the acid cleaning is underway.
Acid cleaning
The object of this phase is to remove the scale, either by total dissolution/sequestration or by making it so loose it is removed during rinsing/flushing phases. The large amounts of iron present in various forms in such scales present a separate problem of their own. It is fine to dissolve the scale and bring iron into solution. Ferric, or trivalent iron ions, however are severely corrosive to elemental iron, unless a method is used to deactivate them :
2Fe3+ + Fe ---> 3Fe2+ ( ferric iron corrosion)
To deactivate this ferric iron, it can either be reduced to ferrous, or 2 valent ions, or sequestered. Sequestering is to combine it with other species in a stable complex, which effectively remove it from the reaction equation.
Inhibited citric acid and ammonium bifluoride
We have seen how ammoniated citric acid stabilizes iron and copper ions in solution as complexes, and how the copper is removed from the boiler and not re-plated by the addition of an oxidizing agent at pH of 9-10.
During any acid cleaning, metallic copper is oxidized by ferric iron to the cupric species :
2Fe3+ + Cu ---> 2Fe2+ + Cu2+
This is a useful reaction, since it absorbs ferric ions and dissolves copper. It has a down side, however, if the dissolved copper is not sequestered. This will plate out on the boiler tube, while dissolving an equivalent amount of iron.
Cu2+ + Fe ---> Cu + Fe2+
Cuprous oxide (copper I oxide) in boiler scale is usually present with metallic copper. This is due to the way copper I undergoes a self-redox reaction to copper and copper II:
2Cu+ ---> Cu + Cu2+
Thus, in an acidic boiler cleaning solution with copper and copper I oxide scale, the ingredients are there for not only ferric iron corrosion, but copper corrosion of the steel, where the corrosive copper II ions are being regenerated. We therefore require a cleaning process which inhibits ferric iron corrosion and is quick enough to avoid excessive copper corrosion of the tubes. This is why we propose a mixture of citric acid and ammonium bifluoride, with a suitable proprietary corrosion inhibitor added.
Citric acid
Even without the addition of ammonia, citric acid will dissolve both ferrous and ferric oxides, forming stable complexes in solution which inhibit ferric iron corrosion. The addition of ammonia till pH of about 4 forms the species monoammonium citric acid ( C6H7O7.NH4 ) and diammonium citric acid (C6H6O7.(NH4)2). Both of these are highly effective in sequestering ferric iron, ferrous iron and cupric copper. The elemental copper is not dissolved at this point.
Ammonium bifluoride, NH4HF2
Addition of this chemical to the citric acid contributes to the ammoniating process described above. It also has several other useful functions.
It forms hydrofluoric acid in solution, which is largely undissociated. This is because hydrofluoric acid is a weak acid, with the hydrogen and fluorine components having affinity for one another. This, however, does not stop it from reacting with, amongst other things silicate scales such as acmite:
Na2O.Fe2O3.4SiO2 + 36HF ---> 2FeF63- +4H2SiF6 + 2Na+ + 4H+ + 12H2O
and ferric oxide:
Fe2O3 + 12HF ---> 2FeF63- + 3H2O + 6H+
and magnetite:
Fe3O4 + 18HF ---> 3FeF63- +4H2O + 10 H+ + e-
The reason all the above take place is the stability of the hexafluoroferric ion, FeF63-.
In fact, adding ammonium bifluoride to citric acid increases dissolution of scale, both in quantity and rate, while lowering the overall corrosion of the system.
Using citric and ammonium bifluoride achieves a combination of ferric ion corrosion inhibition and decreased hydrogen ion activity due to its association with free fluoride.
Ammonium bifluoride can be taken to be a cathodic, or passivating inhibitor in citric acid, since it inhibits the reaction 2H+ + Fe ---> Fe2+ + H2.
Corrosion inhibitor
Even though ammonium bifluoride is inhibiting in nature, a corrosion inhibitor is added to the acid cleaning solution. There are 3 types of corrosion inhibitors :
- Cathodic, which impede the reduction of hydrogen ions
- Anodic, which limit oxidation of the metal, in this case iron
- Adsorption, forming a physical film on the metal surface
Commercially available inhibitors are mixtures of inhibitors and other surfactants in a carrier. They are normally used following the manufacturer's instructions for the application and are extremely effective.
The conclusion of the acid cleaning phase is best determined by analyzing for the two most evident components in the solution, namely dissolved iron and dissolved acid. A variety of wet and optical analytical methods are available. Following a stabilization of both acid and iron values, circulation of solutions is continued further. It is common for the values to rise to a second plateau, so cessation of cleaning immediately upon reaching initial stability is not advisable.
Solutions are fully removed from the boiler and it is flushed to neutrality. When access is possible, all drums, headers and accessible tubes must be water jetted to remove loosened insoluble debris.
Passivation
At the end of the acid cleaning, the boiler surfaces will be of bare metal and most of the copper spread around as elemental plating. During rinsing, exposed steel will "flash-rust". The passivation process will remove the flash-rust and copper in a step-by step process, finally impressing a positive potential on the steel exceeding the passive potential but not exceeding the transpassive potential.
This is achieved by a citric acid solution, ammoniated to a pH of 3.5 to 4 to sequester iron from the rust, followed by ammoniating further to a pH of 9.5. Finally, an oxidizing agent is added to form the semi-conductive iron oxide film and to oxidize elemental copper, as previously discussed.
Sunday, September 21, 2008
CHEMICAL CLEANING
We offer a broad range of chemical cleaning services for virtually any type of vessel and equipment to be cleaned. Plus, our pumps and auxiliary equipment are unsurpassed for power and reliability.
Each job is tailored to the application.
Typically, a pre-operational chemical cleaning job involves the following operations:
Removal of rust preventive compounds, greases, dirt, sand, cutting, oils, etc.
Removal of millscale, rust and other corrosion products.
Neutralisation and passivation of the freshly cleaned metal surfaces.
Our key to providing quality chemical cleaning rests in the engineered selection process. We have the largest variety of solvent systems, including chelants, organic solvents, inhibitors, alkaline cleaners, organic acids emulsions, mineral acids and detergents from which to develop cost-effective chemical cleaning processes. For our cleaning chemistries, we pay strict attention to environmental concerns, which is why we have developed several biodegradable formulations that have no known carcinogens, low personnel exposure risk and minimal impact on sewer and waste water treatment systems.
Chemical filling, cascading, on-stream cleaning, foam, vapor phase and recycled foam are among our chemical cleaning techniques - techniques which can eliminate a range of equipment problems and degass organic compounds. Most of the process used by us are proven industry standards for effectiveness and safety.
Approach
Choosing the right chemistries depending on metallurgy, scales preservation schedules.
Choosing the right equipments like: pumps, temporary piping , fitting , etc. depending on circuit flow, flow restriction, pressure drops, velocities and other parameters.
Choosing sophisticated Laboratory monitoring facilities for right control by monitoring parameters during cleaning for proven results.
Equipments available for Precommissioning Chemical Cleaning:
Skid mounted pressurised hot water generator of 800,000 kcal capacity with output temperature upto 140°C.
Heat exchanger, steam coil equipped circulation tanks.
Motor pump skids upto 400 cubic meter per hour discharge and 90 meter head.
Temporary piping upto 8" dia approximately 3000 mtrs.
Valves, spool prpes, flanges & other fittings hose pipe, steam hose pipe, etc.
Mobile Test Laboratory: Facilities like atomic absorption spectrophotometer, Hach potable spectrophotometer, Auto titrators, Oxidation-Reduction Potentiometer, Glasswares.
FOAM CLEANING
The compressed chemical (solvent) FOAM is generated by the specially designed foam generator is used as the cleaning medium which provides better surface contact than chemical circulation methods and reduces the solvent consumption to 10% thus to eliminate disposal problems of larger volumes of solvents. The Foam Cleaning system is the ideal method for cleaning of process vessels, fin tube exchangers, surface condensers, high pressure steam turbines etc. because of its maximum solvent-to surface exposure so as to reach entire surface without air/gas locks or gaps.
VAPOUR PHASE CLEANING
Our Vapor phase cleaning techniques and equipment's are most appropriate for removing organic fouling from columns, especially those are used in refineries and petrochemical industries. A wide variety of low boiling point solvents and specialty vaporizing equipments are designed to handle to meet any volume of cleaning requirement.
PROCESS: The solvent vapors are introduced into the column/equipment by an overhead line from the vaporizer and allowed the vapor to condense inside the column to flow downward through trays for dissolving the organic material. The condensate/the solution of organic material is then pumped out for rectification and recycling of solvents.
The principal advantage of our vapor phase cleaning facility is that a large column/vessel can be effectively cleaned with a relatively small volume of reclaimable solvent
Saturday, September 20, 2008
SAFCO will permanently close its Dammam unit by September
Saudi Arabian Fertilizer Company (Safco) will permanently close its Dammam urea unit by mid-September in line with a royal decree, a company source at its affiliate SABIC said on Wednesday.
Ossama ahmed Zainy Co for industrial servicing (OZEST) has almost unloaded 80% of the catalyst in safco damam. Now OZEST is working on the NH3 converter 'A' which is one of the oldest non using pyrophoric iron oxide catalyst in the region.
The 330,000 tonne/year urea unit will close within the next month in line with a statement made by the company at the end July.
The source from SABIC (Saudi Basic Industries Corp) said the plant was old, having been constructed in 1965, adding it was now located within a residential area and these two factors supported its closure.
The statement followed a Saudi government decision to shut the plant, at which point a five-year deadline for closure was issued.
The plant also produces around 200,000 tonnes/year of ammonia for captive use, melamine and sulphuric acid.
At present, the plant was still reportedly producing urea as normal.
Ossama ahmed Zainy Co for industrial servicing (OZEST) has almost unloaded 80% of the catalyst in safco damam. Now OZEST is working on the NH3 converter 'A' which is one of the oldest non using pyrophoric iron oxide catalyst in the region.
The 330,000 tonne/year urea unit will close within the next month in line with a statement made by the company at the end July.
The source from SABIC (Saudi Basic Industries Corp) said the plant was old, having been constructed in 1965, adding it was now located within a residential area and these two factors supported its closure.
The statement followed a Saudi government decision to shut the plant, at which point a five-year deadline for closure was issued.
The plant also produces around 200,000 tonnes/year of ammonia for captive use, melamine and sulphuric acid.
At present, the plant was still reportedly producing urea as normal.
Wednesday, August 20, 2008
Outside Bundle Cleaner
Ozest have the outside bundle cleaner XL. This system was developed in cooperation with several high pressure cleaning specialists in order to bring you a safe and efficient cleaning machine to clean the outside of your bundles fast, safe and easy.
The tube bundle is placed on two optional heavy duty rollers, which can be controlled from the cabin of the operator. The bundles are being cleaned by means of a horizontally driven nozzle bar, which can also move vertically and towards the bundle to get the best cleaning results. The right combination of water pressure (up to an optional 1500 bar) and flow, removes scaling, coke, polymers, etc. without the use of any additional cleaning materials.
The outside bundle cleaner XL has a horizontal stroke of 11 metres and the maximum height is 2.70 metres. The speed is adjustable from the cabin from 0-1 m/sec in order to get the best cleaning results.
All hydraulic controls are placed in the cabin where the operator can sit comfortably and safely without being exposed to the dirt coming back from the bundle. The power pack is situated behind the cabin, easily accessible and all hydraulic hoses are fitted with quick connectors for easy transportation.
As an machine can handle a lot more water to clean in between the tubes, the bundle can be cleaned all the way up to the centre and the risks for accidents is down to a minimum.
Safety
Because the operator can only operate the unit from the cabin, he is well protected from any dirt or high pressure water exiting from the tubes. An emergency shut off valve is also fitted in the cabin and the whole assembly has been build according to the latest CE regulations. All hydraulic cylinders and motors are fitted with safety valves.
Efficiency
Because of the variable speed control and the possibility to control all movements from the cabin, the outside bundle cleaner is a simple and effective machine, witch will prove to be also very cost effective. The unit can easily be dismantled into 3 pieces for easier transportation and in order to save space. The unit is completely equipped with quick connectors for easy removal of all hydraulic hoses.
The tube bundle is placed on two optional heavy duty rollers, which can be controlled from the cabin of the operator. The bundles are being cleaned by means of a horizontally driven nozzle bar, which can also move vertically and towards the bundle to get the best cleaning results. The right combination of water pressure (up to an optional 1500 bar) and flow, removes scaling, coke, polymers, etc. without the use of any additional cleaning materials.
The outside bundle cleaner XL has a horizontal stroke of 11 metres and the maximum height is 2.70 metres. The speed is adjustable from the cabin from 0-1 m/sec in order to get the best cleaning results.
All hydraulic controls are placed in the cabin where the operator can sit comfortably and safely without being exposed to the dirt coming back from the bundle. The power pack is situated behind the cabin, easily accessible and all hydraulic hoses are fitted with quick connectors for easy transportation.
As an machine can handle a lot more water to clean in between the tubes, the bundle can be cleaned all the way up to the centre and the risks for accidents is down to a minimum.
Safety
Because the operator can only operate the unit from the cabin, he is well protected from any dirt or high pressure water exiting from the tubes. An emergency shut off valve is also fitted in the cabin and the whole assembly has been build according to the latest CE regulations. All hydraulic cylinders and motors are fitted with safety valves.
Efficiency
Because of the variable speed control and the possibility to control all movements from the cabin, the outside bundle cleaner is a simple and effective machine, witch will prove to be also very cost effective. The unit can easily be dismantled into 3 pieces for easier transportation and in order to save space. The unit is completely equipped with quick connectors for easy removal of all hydraulic hoses.
Inside Bundle Cleaner IBC-5
In order to meet the demands of high pressure cleaning contractors, Ozest haveInside Bundle Cleaner. The IBC 5 is one of the fastest cleaning machines in the world today and has been designed to clean a large number of bundles on the cleaning slab, during shutdowns.
Our goal was to design a machine which can be fully operated from inside the cabin by 1 operator, in a very simple and efficient way. From the cabin, the operator can control the up/down/left/right movement with a simple joystick, the rollers can be turned, the outriggers can be operated and the lancebed can be moved forward and backwards ± 60 cm. The lancebed has been created out of 10 meter long T-bars, which give a perfect guide for the lances and at the same time avoid dirt from remaining in the lancebed.
Adjustment of the pitch is done by tightening nuts, which keeps the pitch fixed at all times and because the lance bed and the pitch are not covered, it is very clear to see for the operator if his lances are in the right position. The chains, which drive the lances, are located in a tray with a Teflon liner to avoid damage to the metal and the chain is being tensioned by a tandem construction, which avoids the chain from slapping against the metal.
The length of the lances which move into the tubes can be set by using sensors, to prevent lances from damaging and entering too far. Especially in cases with hairpin bundles, this can be very effective. At the same time, the hydraulic power to move the lances forward can be adjusted, to prevent the lances from breaking in case of a blockage. In case there is a problem with a hose or a lance, they can be replaced in a matter of minutes by removing the guide pieces at the front.
Safety
In order to make the machine as safe as possible, we have made 2 standard emergency stops on the machine, 1 inside the cabin and 1 outside at the backside. If you enter with the lances inside a tube, all other hydraulic controls will be blocked. The cabin will lock itself at any height when there is a hydraulic failure during lifting/lowering. The machine has been build according to the latest CE regulations.
Efficiency
Due to the weight of the machine and its speed of the lances, it is a very stable and fast machine which has enough power to clean bundles very fast and therefore cost effective. All controls are located inside the cabin, next to the operator, to create an unobstructed view and comfortable working position.
Aerial Tube Bundle Extractor
A fast, safe and self contained unit to deal with all your bundle extracting problems.
Ozesthave Aerial Tube Bundle Extractor is a self contained unit, which is easily lifted into position by just one crane and can be operated by remote control. Because the unit is equipped with a small diesel engine, it can work independently at any place. The Extractor is standard equipped with a spark arrestor and it can even be equipped with a chalwin valve to make it possible to work even in dangerous areas.
The standard extractor is 8.00m in length and weighs 8,5T. It is suitable for use on all plate and tube heat exchangers up to 2.00m diameter and a maximum bundle weight of 40T. In case you might need a bigger or a smaller extractor, Peinemann can also make custom made extractors to suit your needs.
The Aerial Tube Bundle Extractor uses a special lifting frame, which is constructed in such a way that it has a maximum reach into the construction. The load is trimmed using a Aerial balancing cylinder which makes it also easy to off load the bundles when the extractor is put down on the ground. Due to the use of a pulling hook mechanism and 2 butt plates which are clamped against the extractor’s shell, the massive power of 50.000kgf is compensated against the shell flange and not against the structure. With over 10 years of experience in the field of bundle extracting, you can always count on ozest as your partner.
Monday, August 18, 2008
CORROSSION INHIBITOR
Corrossion inhibitor has got a very important role in chemical cleaning. A corrosion inhibitor is a chemical compound that, when added to a fluid or gas, decreases the corrosion rate of a metal or an alloy.
The effectiveness, or corrosion inhibition efficiency, of a corrosion inhibitor is a function of many factors like: fluid composition, quantity of water, flow regime.... If the correct inhibitor and quantity is selected then is possible to achieve high, 90-99%, efficiency, but this higher values shall be documented by laboratory and field test. Some of the mechanisms of its effect are formation of a passivation layer (a thin film on the surface of the material that stops access of the corrosive substance to the metal), inhibiting either the oxidation or reduction part of the redox corrosion system (anodic and cathodic inhibitors), or scavenging the dissolved oxygen.
Some corrosion inhibitors are hexamine, phenylenediamine, dimethylethanolamine, sodium nitrite, cinnamaldehyde, condensation products of aldehydes and amines (imines), chromates, nitrites, phosphates, hydrazine, ascorbic acid, and others. The suitability of any given chemical for a task in hand depends on many factors, from the material of the system they have to act in, to the nature of the substances they are added into and their operating temperature.
An example of an anodic inhibitor is chromate which forms a passivation layer on aluminum and steel surfaces which prevents the oxidation of the metal. Unfortunately, chromate is carcinogenic in humans; the toxicity of chromates was featured in the film Erin Brockovich. Like hydrazine, the use of chromate to protect metal surfaces has been limited; for instance it is banned from some products.
Nitrite is another anodic inhibitor. If anodic inhibitors are used at too low concentration, they can actually aggravate pitting corrosion, as they form a nonuniform layer with local anodes.
An example of a cathodic inhibitor is zinc oxide, which retards the corrosion by inhibiting the reduction of water to hydrogen gas. As every oxidation requires a reduction to occur at the same time it slows the oxidation of the metal. As an alternative to the reduction of water to form hydrogen, oxygen or nitrate can be reduced. If oxidants such as oxygen are excluded, the rate of the corrosion can be controlled by the rate of water reduction; this is the case in a closed recirculating domestic central heating system, where the water in the radiators soon becomes anaerobic. This is a very different situation to the corrosion in a car door where the water is aerobic. For instance, cars suffer from the fact that water can enter the cavity inside the door and become trapped there. The fact that the oxygen concentration is not uniform within the layer of water in the door then creates a differental aeration cell leading to corrosion. A cathodic inhibitor would be of little use in such a situation as even after inhibiting the reduction of water, the reduction of dioxygen would still be able to occur. A better method of preventing corrosion in the car door would be to improve the design to prevent water being trapped in the door and to consider using an anodic inhibitor such as phosphate.
One very good example of a cathodic inhibitor is a volatile amine present in steam; these are used in the boilers used to drive turbines to protect the pipework in which the condensed water passes. Here the amine is moved by the steam in a steam distillation to the remote pipework. The amine increases the pH thereby making proton reduction less favorable. It is also possible that with correct choice, the amine can form a protective film on the steel surface and, at the same time, act as an anodic inhibitor. An inhibitor that acts both in a cathodic and anodic manner is termed a mixed inhibitor. Hydrazine and ascorbic acid (vitamin C) both help reduce the rate of corrosion in boilers by removing the dissolved oxygen from the water. However, as hydrazine is a highly toxic carcinogen, its use is being discouraged.
Antiseptics are used to counter microbial corrosion. Benzalkonium chloride is commonly used in oil field industry.
Corrosion inhibitors are commonly added to coolants, fuels, hydraulic fluids, boiler water, engine oil, and many other fluids used in industry.
For fuels, various corrosion inhibitors can be used
DCI-4A, widely used in commercial and military jet fuels, acts also as a lubricity additive. Can be also used for gasolines and other distillate fuels.
DCI-6A, for motor gasoline and distillate fuels, and for U.S. military fuels
DCI-11, for alcohols and gasolines containing oxygenates
DCI-28, for very low-pH alcohols and gasolines containing oxygenates
DCI-30, for gasoline and distillate fuels, excellent for pipeline transfers and storage, caustic-resistant
DMA-4 (solution of alkylaminophosphate in kerosene), for petroleum distillates
Corrosion inhibitors are often added to paints. A pigment with anticorrosive properties is zinc phosphate. Compounds derived from tannic acid (e.g. Kelate) or zinc salts of organonitrogens (e.g. Alcophor 827) can be used together with anticorrosive pigments. Other corrosion inhibitors are Anticor 70, Albaex, Ferrophos, and Molywhite MZAP.
and in chemical cleaning Rodine, Armohib, HAI, Nevamine are used according to chemicals and their concentration.
The effectiveness, or corrosion inhibition efficiency, of a corrosion inhibitor is a function of many factors like: fluid composition, quantity of water, flow regime.... If the correct inhibitor and quantity is selected then is possible to achieve high, 90-99%, efficiency, but this higher values shall be documented by laboratory and field test. Some of the mechanisms of its effect are formation of a passivation layer (a thin film on the surface of the material that stops access of the corrosive substance to the metal), inhibiting either the oxidation or reduction part of the redox corrosion system (anodic and cathodic inhibitors), or scavenging the dissolved oxygen.
Some corrosion inhibitors are hexamine, phenylenediamine, dimethylethanolamine, sodium nitrite, cinnamaldehyde, condensation products of aldehydes and amines (imines), chromates, nitrites, phosphates, hydrazine, ascorbic acid, and others. The suitability of any given chemical for a task in hand depends on many factors, from the material of the system they have to act in, to the nature of the substances they are added into and their operating temperature.
An example of an anodic inhibitor is chromate which forms a passivation layer on aluminum and steel surfaces which prevents the oxidation of the metal. Unfortunately, chromate is carcinogenic in humans; the toxicity of chromates was featured in the film Erin Brockovich. Like hydrazine, the use of chromate to protect metal surfaces has been limited; for instance it is banned from some products.
Nitrite is another anodic inhibitor. If anodic inhibitors are used at too low concentration, they can actually aggravate pitting corrosion, as they form a nonuniform layer with local anodes.
An example of a cathodic inhibitor is zinc oxide, which retards the corrosion by inhibiting the reduction of water to hydrogen gas. As every oxidation requires a reduction to occur at the same time it slows the oxidation of the metal. As an alternative to the reduction of water to form hydrogen, oxygen or nitrate can be reduced. If oxidants such as oxygen are excluded, the rate of the corrosion can be controlled by the rate of water reduction; this is the case in a closed recirculating domestic central heating system, where the water in the radiators soon becomes anaerobic. This is a very different situation to the corrosion in a car door where the water is aerobic. For instance, cars suffer from the fact that water can enter the cavity inside the door and become trapped there. The fact that the oxygen concentration is not uniform within the layer of water in the door then creates a differental aeration cell leading to corrosion. A cathodic inhibitor would be of little use in such a situation as even after inhibiting the reduction of water, the reduction of dioxygen would still be able to occur. A better method of preventing corrosion in the car door would be to improve the design to prevent water being trapped in the door and to consider using an anodic inhibitor such as phosphate.
One very good example of a cathodic inhibitor is a volatile amine present in steam; these are used in the boilers used to drive turbines to protect the pipework in which the condensed water passes. Here the amine is moved by the steam in a steam distillation to the remote pipework. The amine increases the pH thereby making proton reduction less favorable. It is also possible that with correct choice, the amine can form a protective film on the steel surface and, at the same time, act as an anodic inhibitor. An inhibitor that acts both in a cathodic and anodic manner is termed a mixed inhibitor. Hydrazine and ascorbic acid (vitamin C) both help reduce the rate of corrosion in boilers by removing the dissolved oxygen from the water. However, as hydrazine is a highly toxic carcinogen, its use is being discouraged.
Antiseptics are used to counter microbial corrosion. Benzalkonium chloride is commonly used in oil field industry.
Corrosion inhibitors are commonly added to coolants, fuels, hydraulic fluids, boiler water, engine oil, and many other fluids used in industry.
For fuels, various corrosion inhibitors can be used
DCI-4A, widely used in commercial and military jet fuels, acts also as a lubricity additive. Can be also used for gasolines and other distillate fuels.
DCI-6A, for motor gasoline and distillate fuels, and for U.S. military fuels
DCI-11, for alcohols and gasolines containing oxygenates
DCI-28, for very low-pH alcohols and gasolines containing oxygenates
DCI-30, for gasoline and distillate fuels, excellent for pipeline transfers and storage, caustic-resistant
DMA-4 (solution of alkylaminophosphate in kerosene), for petroleum distillates
Corrosion inhibitors are often added to paints. A pigment with anticorrosive properties is zinc phosphate. Compounds derived from tannic acid (e.g. Kelate) or zinc salts of organonitrogens (e.g. Alcophor 827) can be used together with anticorrosive pigments. Other corrosion inhibitors are Anticor 70, Albaex, Ferrophos, and Molywhite MZAP.
and in chemical cleaning Rodine, Armohib, HAI, Nevamine are used according to chemicals and their concentration.
Saturday, August 9, 2008
Passivation
Passivation is the process of making a material "passive" in relation to another material prior to using the materials together. For example, prior to storing hydrogen peroxide in an aluminium container, the container can be passivated by rinsing it with a dilute solution of nitric acid and peroxide alternating with deionized water. The nitric acid and peroxide oxidizes and dissolves any impurities on the inner surface of the container, and the deionized water rinses away the acid and oxidized impurities. Another typical passivation process of cleaning stainless steel tanks involves cleaning with NaOH and citric acid followed by nitric acid (up to 20% at 120F) and a complete water rinse. This process will restore the film, remove metal particles, dirt, and welding generated compounds (e.g. oxides).
In the context of corrosion, passivation is the spontaneous formation of a hard non-reactive surface film that inhibits further corrosion. This layer is usually an oxide or nitride that is a few atoms thick.
Passivation is a process performed to make a surface passive, i.e., a surface film is created that causes the surface to lose its chemical reactivity. Passivation unipotentializes the stainless steel with the oxygen absorbed by the metal surface, creating a monomolecular oxide film. Passivation can result in the very much-desired low corrosion rate of the metal.
It is seen that most of the fabricators are using the passivation solution for only the weld pool line or the heat dissipation areas. But that doesn’t ensures from risk of corrosion since the pitting on the remaining surface remain untreated as well as the corrosion susceptible gray zone remains forever. The simple spatters of the grinding also get indented into the surface and it causes the seeding for the corrosion. The chromium in the Stainless steel is playing anticorrosive roll in the play by forming the Cr2O3 Chromic Oxide. But it doesn’t guard against free ferrite on the surface.
With our passivation treatment on total area the there is hardly any corrosion susceptibility since all dirt is dissolved and the surface gets converted to the higher oxidation status as uniform film it becomes redundant to further corrosive attacks.
The passivation cost per square meter area is very less against the life and quality it ensures to the precision products.So we recommend always to go for total Passivation.
Mechanisms of passivation
Under normal conditions of pH and oxygen concentration, passivation is seen in such materials as aluminium, iron, zinc, magnesium, copper, stainless steel, titanium, and silicon. Ordinary steel can form a passivating layer in alkali environments, as rebar does in concrete. The conditions necessary for passivation are recorded in Pourbaix diagrams.
Some corrosion inhibitors help the formation of a passivation layer on the surface of the metals to which they are applied.
Electrochemical passivation processes
Some compounds, dissolving in solutions (chromates, molybdates) form non-reactive and low solubility films on metal surfaces.
Passivation of specific materials
Aluminium may be protected from oxidation by anodizing and/or allodizing (sometimes called Alodining), or any of an assortment of similar processes. In addition, stacked passivation techniques are often used for protecting aluminium. For example, chromating is often used as a sealant to a previously-anodized surface, to increase resistance to salt-water exposure of aluminium parts by nearly a factor of 2 versus simply relying on anodizing.
Iron based (ferrous) materials, including steel, may be somewhat protected by promoting oxidation ("rust") and then converting the oxidation to a metalophosphate by using phosphoric acid and further protected by surface coating. As the uncoated surface is water-soluble a preferred method is to form manganese or zinc compounds by a process commonly known as Parkerizing. Older, less-effective but chemically-similar electrochemical conversion coatings included bluing, also known as black oxide.
Nickel can be used for handling elemental fluorine, thanks to a passivation layer of nickel fluoride.
Terminology for assorted passivation processes
Bluing, also known as black oxide, and sometimes called browning when used in reference to historical processes dating from the 18th Century, is a passivation coating for the surfaces of iron and steel objects. It is one of the oldest passivation processes.
Newer, proprietary (and/or trademarked) processes for conversion coatings include Parkerized for passivating steel, dating to roughly 1912, and Alodine for passivating aluminium; both are trademarked processes and are now owned by Henkel Surface Technologies.
Chem film is any generic chromate conversion coating used to passivate aluminium. One such example is U.S. Patent 5,304,257. In general, however, chromate can also mean any of several chromate conversion coatings that can be applied to a much wider range of metals and alloys than just to aluminium. In recent years, chromate coatings have become less popular due to concerns over environmental pollution from using such processes.
Iridite is another trademarked name of a whole family of proprietary conversion coatings owned by MacDermid. A competing conversion coating used on aluminium, that somewhat ameliorates the environmental pollution concerns caused by chromate coatings, it often appears as a slightly yellowish coating, of roughly the same color as a yellow highlighting pen used to mark text on paper.
Rationale for passivating aluminium
Aluminium naturally forms an oxide almost immediately that protects it from further oxidation in many environments. This naturally-occurring oxide provides no protection during exposure to any saltwater spray environments, such as occurs in areas near bodies of saltwater. In such coastal environments, unprotected aluminium will turn white, corrode, and largely vanish over periods of exposure as short as a few years. The only way to prevent this from occurring is to use a more robust conversion coating on aluminium surfaces that will not be affected by the saltwater atmosphere. Alodine, Iridite, and chem film coatings can provide varying amounts of protection for aluminium surfaces.
In the context of corrosion, passivation is the spontaneous formation of a hard non-reactive surface film that inhibits further corrosion. This layer is usually an oxide or nitride that is a few atoms thick.
Passivation is a process performed to make a surface passive, i.e., a surface film is created that causes the surface to lose its chemical reactivity. Passivation unipotentializes the stainless steel with the oxygen absorbed by the metal surface, creating a monomolecular oxide film. Passivation can result in the very much-desired low corrosion rate of the metal.
It is seen that most of the fabricators are using the passivation solution for only the weld pool line or the heat dissipation areas. But that doesn’t ensures from risk of corrosion since the pitting on the remaining surface remain untreated as well as the corrosion susceptible gray zone remains forever. The simple spatters of the grinding also get indented into the surface and it causes the seeding for the corrosion. The chromium in the Stainless steel is playing anticorrosive roll in the play by forming the Cr2O3 Chromic Oxide. But it doesn’t guard against free ferrite on the surface.
With our passivation treatment on total area the there is hardly any corrosion susceptibility since all dirt is dissolved and the surface gets converted to the higher oxidation status as uniform film it becomes redundant to further corrosive attacks.
The passivation cost per square meter area is very less against the life and quality it ensures to the precision products.So we recommend always to go for total Passivation.
Mechanisms of passivation
Under normal conditions of pH and oxygen concentration, passivation is seen in such materials as aluminium, iron, zinc, magnesium, copper, stainless steel, titanium, and silicon. Ordinary steel can form a passivating layer in alkali environments, as rebar does in concrete. The conditions necessary for passivation are recorded in Pourbaix diagrams.
Some corrosion inhibitors help the formation of a passivation layer on the surface of the metals to which they are applied.
Electrochemical passivation processes
Some compounds, dissolving in solutions (chromates, molybdates) form non-reactive and low solubility films on metal surfaces.
Passivation of specific materials
Aluminium may be protected from oxidation by anodizing and/or allodizing (sometimes called Alodining), or any of an assortment of similar processes. In addition, stacked passivation techniques are often used for protecting aluminium. For example, chromating is often used as a sealant to a previously-anodized surface, to increase resistance to salt-water exposure of aluminium parts by nearly a factor of 2 versus simply relying on anodizing.
Iron based (ferrous) materials, including steel, may be somewhat protected by promoting oxidation ("rust") and then converting the oxidation to a metalophosphate by using phosphoric acid and further protected by surface coating. As the uncoated surface is water-soluble a preferred method is to form manganese or zinc compounds by a process commonly known as Parkerizing. Older, less-effective but chemically-similar electrochemical conversion coatings included bluing, also known as black oxide.
Nickel can be used for handling elemental fluorine, thanks to a passivation layer of nickel fluoride.
Terminology for assorted passivation processes
Bluing, also known as black oxide, and sometimes called browning when used in reference to historical processes dating from the 18th Century, is a passivation coating for the surfaces of iron and steel objects. It is one of the oldest passivation processes.
Newer, proprietary (and/or trademarked) processes for conversion coatings include Parkerized for passivating steel, dating to roughly 1912, and Alodine for passivating aluminium; both are trademarked processes and are now owned by Henkel Surface Technologies.
Chem film is any generic chromate conversion coating used to passivate aluminium. One such example is U.S. Patent 5,304,257. In general, however, chromate can also mean any of several chromate conversion coatings that can be applied to a much wider range of metals and alloys than just to aluminium. In recent years, chromate coatings have become less popular due to concerns over environmental pollution from using such processes.
Iridite is another trademarked name of a whole family of proprietary conversion coatings owned by MacDermid. A competing conversion coating used on aluminium, that somewhat ameliorates the environmental pollution concerns caused by chromate coatings, it often appears as a slightly yellowish coating, of roughly the same color as a yellow highlighting pen used to mark text on paper.
Rationale for passivating aluminium
Aluminium naturally forms an oxide almost immediately that protects it from further oxidation in many environments. This naturally-occurring oxide provides no protection during exposure to any saltwater spray environments, such as occurs in areas near bodies of saltwater. In such coastal environments, unprotected aluminium will turn white, corrode, and largely vanish over periods of exposure as short as a few years. The only way to prevent this from occurring is to use a more robust conversion coating on aluminium surfaces that will not be affected by the saltwater atmosphere. Alodine, Iridite, and chem film coatings can provide varying amounts of protection for aluminium surfaces.
Sunday, July 27, 2008
pulling bundle with TMBP
The Truck Mounted Bundle Extractor is a proven machine which is developed in order to extract and push back horizontal bundles which are located at a height between 500 and 7000 mm and with a maximum weight of 15 tons. Due to it’s unique and patented design, this machine is not only designed to pull and push back bundles, it can also be used to transport the bundles to the cleaning slab. Therefore it is highly appreciated in all the refineries and in the petrochemical sector.
The main advantage is that you don’t need a crane any more, which will reduce your costs and bring your downtime back to a minimum. Less organisation is needed.
The truck is allowed to drive on the public road, therefore making it a versatile and efficient tool. Even in a difficult to reach place with a crane, e.g. when there is a pipe frame above the heat exchanger, the truck mounted bundle puller can still do the job!
Once the extractor is in position and the butt plates are positioned against the shell flange, the extractor can exert a force of 50.000 kg, enough to extract even the most obstinate bundle. After the initial break, the hydraulic pulling car will be hooked to the pipe plate and the extractor can pull out the bundle in one continuous stroke. Once the bundle is resting on the truck, it can be transported to the cleaning slab and can be off loaded by the crane on the cleaning slab.
Saturday, July 26, 2008
TWISTED TUBE HEAT EXCHANGER TECHNOLOGY
ABSTRACT
Over 85% of all new heat exchanger applications in oil refining, chemical, petro-chemical, and power generation are accommodated through the use of conventional shell and tube type heat exchangers. The fundamental basis for this statistic is shell and tube technology is a cost effective, proven solution for a wide variety of heat transfer requirements. However, there are limitations associated with the technology which include inefficient usage of shell side pressure drop, dead or low flow zones around the baffles where fouling and corrosion can occur, and flow induced tube vibration, which can ultimately result in equipment failure. This paper presents a recent innovation and development of a new technology, known as Twisted Tube technology, which has been able to overcome the limitations of the conventional technology, and in addition, provide superior overall heat transfer coefficients through tube side enhancement. This paper compares the construction, performance, and economics of Twisted Tube exchangers against conventional designs for various materials of construction including reactive metals.
KEYWORDS
heat exchanger, twisted tube technology, heat transfer, corrosion resistance
CONVENTIONAL SHELL AND TUBE DESIGN
Conventional TEMA (Tubular Exchanger Manufacturers Association) type shell and tube type heat exchangers consist of a number of round tubes attached to a tubesheet inside a cylindrical vessel, with tube sizes, tube lengths, and shell diameters varying depending on the requirements of the application. Heat transfer surface areas can vary from a few square feet to over 25,000 square feet. The tube bundle normally contains a number of baffles to accomplish the dual objectives of providing a support structure for the tubes, and to direct the shell-side flow across the tubes rather than along the tubes . The resulting back and forth shell-side flow will yield a higher than expected pressure drop per unit of heat transfer because energy is used to reverse the flow rather than to enhance heat transfer. Also, the energy consumed in reversing the flow will tend to force the shell-side fluid through baffle-to-tube and baffle-to-shell clearances yielding lower cross flow and lower heat transfer coefficients. Finally, fluid flow around the baffles is non-uniform resulting in areas of low flow and dead spots, which are prone to fouling accumulation, corrosion, and poor heat transfer.
The thermal effectiveness (x), of a shell and tube exchanger is normally calculated assuming perfect radial and no axial mixing of the shell side stream. In practice however, there is considerable axial mixing within a baffle compartment, and further, the stream is in cross-flow for part of the time rather than axial flow. These effects are further complicated by leakage of flow that occurs at the baffle-to-tube and baffle-to-shell joints that does not take full part in the heat transfer in the bundle. The overall effect of these limitations is the actual thermal effectiveness (x) will be lower than the theoretical value, and it will be lower than the values obtained for other types of heat exchangers that do not suffer from these limitations. Typically, thermal effectiveness of a conventional shell and tube type exchanger will be in the range of 60% to 80% The Twisted Tube Heat Exchanger
The Twisted Tube heat exchanger originated in Eastern Europe and became commercially available in Scandinavia in the mid 1980’s. It was developed primarily to
overcome the limitations inherent with conventional shell and tube technology. Applications of Twisted Tube technology were primarily in single phase and condensing duties in pulp and paper and district heating with limited exposure in the process industries. In 1991, Koch licensed the technology and in 1995 subsequently acquired the technology outright.
Construction
The Twisted Tube exchanger consists of a bundle of uniquely formed tubes assembled in a bundle without the use of baffles. The tubes have been subjected to a unique forming process which results in an oval cross section with a superimposed helix
Figure 2. Twisted Tube Heat Exchanger Bundle providing a helical tube-side flow path . The forming process ensures that tube wall thickness remains constant and the material yield point is not exceeded thereby retaining mechanical integrity. The tube ends are round to allow conventional tube to tubesheet joints.
. Tube-side Flow Path
A wide range of tube materials can be used including carbon and stainless steels, Cr-Mo alloys, duplex and super duplex alloys as well as titanium, zirconium and tantalum. Tube sizes may vary from ½ inch to 1 inch.
Tubes are assembled into a bundle on a triangular pitch one row at a time with each tube being turned to align the twists at every plane along the bundle length. This alignment results in tubes contacting adjacent tubes at many points along the length of the tube in the bundle (Fig 4). The completed bundle is then tightly strapped circumferentially to ensure no tube movement and a robust bundle is the end result. Bundles can be constructed with more than 5000 tubes and up to 6 feet in diameter with tube lengths up to 80 feet.. Tube Alignment and Support. Completed Twisted Tube Bundle
The shell-side flow path is complex and predominantly axial in nature. Typically, the shell side flow area is approximately equal to the tube side flow area. The bundle is often shrouded to ensure shell side flow remains in the bundle and minimizes bypassing. Paths are available to allow the fluid to flow into and out of the bundle at each end. When high inlet and outlet velocities must be avoided, “vapor belts” may be used as with conventional designs. The Twisted Tube design imparts a swirl flow to the tube-side fluid enhancing the tube-side heat transfer coefficient.
Shell-side Interrupted Swirl Flow
Advantages
Thermal and Hydraulic Performance Elimination of the shell-side back and forth flow path with a more unidirectional flow yields a much higher heat transfer coefficient per unit of pressure drop. Typically, heat transfer coefficients are 40% higher for the same pressure drop or, conversely, pressure drops are halved for the same heat transfer coefficient. Moreover, the tube-side swirl induced flow enhances the coefficients by an amount similar to that of twisted tape or turbulator inserts in a plain round tube. The overall effect of this is a substantial reduction of heat transfer area for a twisted tube exchanger compared with a conventional exchanger for the same duty. Alternatively, significant improvements in the performance of an existing exchanger can be achieved by replacing a conventional bundle with a Twisted Tube bundle.
Higher Thermal Effectiveness The closer approach to pure plug flow on the shell-side means that designs achieving higher thermal effectiveness, more typical of plate type exchangers, are possible with Twisted Tube exchangers
Lower Fouling and Cleanability The elimination of dead spots on the shell-side and the increased turbulence, both on the shell-side and the tube-side results in reduced fouling. Particulate fouling is reduced by the scouring action. Other types of fouling such as scaling and chemical reaction products are prevented by the removal of hot spots. Fouling characteristics are therefore, more typical of those found in plate exchangers rather than shell and tube type exchangers. The lower shell side pressure drop for a given flow means that higher velocities are possible, thereby reducing clogging and plugging with fibrous materials. Should fouling occur, the twist alignment in the twisted tube exchanger provides cleaning lanes even though the bundle is constructed using triangular pitch tube layout. Hence, the cleanability of a conventional square pitch layout is combined with heat transfer area density of a triangular layout.
Vibration Elimination Flow induced vibration can occur in conventional exchangers although special precautions such as “no tubes in window” are available to overcome the problem by providing more tube support. The most damaging vibration arises from fluid-elastic instability that can lead to damage within a few hours of operation. The possibility of such vibration in twisted tube exchangers is completely eliminated by axial flow and because the tubes are supported approximately every two inches along the tube length. Clearly, there is some cross-flow at the inlet and outlet regions but good tube support effectively mitigates this potential for failure. Further, the cleaning lanes provide additional smooth paths with a flow entering and exiting the bundle.
Codes and MembershipsTwisted tube heat exchangers are manufactured to most codes including A D Merkblatter, ASME, B,BS, CODAP, HPGCL, ISPSEL, STOOMWEZEN, and TEMA. Brown Fintube is a member of ASM,ASME, AWS, AQS, HTFS, HTRI, ILTA, NACE, and SME, and manufactures Twisted Tubeexchangers in Houston TX, Luxembourg and in Asia through strategic alliance.
Applications Over 400 Twisted Tube heat exchangers have been designed, built and delivered. A partial list of applications shows a Twisted Tube exchanger bundle being installed in an existing shell in a North American facility. Table 2 contains a comparison of Twisted Tube exchangers and conventional shell and tube exchangers for actual applications including heat transfer surface area and cost savings. Data presented in table 2 are for units constructed with carbon steel, however, in general, in the correct application, cost savings through the use of twisted tube will vary directly with the material cost and the surface area of the heat exchanger. Stated differently, greater savings can be realized as the cost of the material increases. Installation of Twisted Tube Bundle Table I. Applications of Twisted Tube Heat Exchangers
Industry Application
Chemical Petroleum
Pulp & Paper
Power Steel
Mining / Mineral Processing District Heating
Sulfuric acid cooling Ammonia preheating Hydrogen peroxide heating / cooling High pressure gas heating / cooling Crude oil heating Bitumen heating LNG heating Black liquor heating / cooling White water cooling Oil heating / cooling Effluent cooling Turbine steam condensing Boiler feed water heating Lube oil cooling Quench oil cooling Compressed gas cooling Lube oil cooling Liquor cooling Effluent cooling Closed loop water heating
Steam heating
Table II. Comparison of Twisted Tube and Conventional Heat Exchangers
Service Feed / Bottoms Lean / Rich Crude Oil MVGO Exchanger DEA Cooler Product Cooler
Shell-side
Fluid Stripped Water Lean DEA Crude Oil MVGO Product Temp In/Out deg F 250 / 138 244 / 134 122 / 97 260 / 180
Tube-side
Fluid Sour Water Rich DEA Sour Water Water Temp In/Out deg F 100/201 97 / 200 64 / 73 125 / 174
Surface Area Conv / Twisted Conv / Twisted Conv / Twisted Conv / Twisted Square feet 9612 / 4746 1151 / 764 8966 / 5511 2163 / 1097
Cost Conv / Twisted Conv / Twisted Conv / Twisted Conv / Twisted $, 000 $130 / $90 $35 / $25 $215 / $170 $40 / $30
CONCLUSIONS
The construction, thermal characteristics, performance, and use of Twisted Tube type heat exchangers have been reviewed. It has been shown that this type of exchanger offers a number of advantages over the conventional shell and tube exchanger with segmental baffles. In suitable applications, Twisted Tube heat exchangers offers superior economic performance as defined by cost per unit heat load when compared to the alternative of conventional shell and tube type equipment.
Over 85% of all new heat exchanger applications in oil refining, chemical, petro-chemical, and power generation are accommodated through the use of conventional shell and tube type heat exchangers. The fundamental basis for this statistic is shell and tube technology is a cost effective, proven solution for a wide variety of heat transfer requirements. However, there are limitations associated with the technology which include inefficient usage of shell side pressure drop, dead or low flow zones around the baffles where fouling and corrosion can occur, and flow induced tube vibration, which can ultimately result in equipment failure. This paper presents a recent innovation and development of a new technology, known as Twisted Tube technology, which has been able to overcome the limitations of the conventional technology, and in addition, provide superior overall heat transfer coefficients through tube side enhancement. This paper compares the construction, performance, and economics of Twisted Tube exchangers against conventional designs for various materials of construction including reactive metals.
KEYWORDS
heat exchanger, twisted tube technology, heat transfer, corrosion resistance
CONVENTIONAL SHELL AND TUBE DESIGN
Conventional TEMA (Tubular Exchanger Manufacturers Association) type shell and tube type heat exchangers consist of a number of round tubes attached to a tubesheet inside a cylindrical vessel, with tube sizes, tube lengths, and shell diameters varying depending on the requirements of the application. Heat transfer surface areas can vary from a few square feet to over 25,000 square feet. The tube bundle normally contains a number of baffles to accomplish the dual objectives of providing a support structure for the tubes, and to direct the shell-side flow across the tubes rather than along the tubes . The resulting back and forth shell-side flow will yield a higher than expected pressure drop per unit of heat transfer because energy is used to reverse the flow rather than to enhance heat transfer. Also, the energy consumed in reversing the flow will tend to force the shell-side fluid through baffle-to-tube and baffle-to-shell clearances yielding lower cross flow and lower heat transfer coefficients. Finally, fluid flow around the baffles is non-uniform resulting in areas of low flow and dead spots, which are prone to fouling accumulation, corrosion, and poor heat transfer.
The thermal effectiveness (x), of a shell and tube exchanger is normally calculated assuming perfect radial and no axial mixing of the shell side stream. In practice however, there is considerable axial mixing within a baffle compartment, and further, the stream is in cross-flow for part of the time rather than axial flow. These effects are further complicated by leakage of flow that occurs at the baffle-to-tube and baffle-to-shell joints that does not take full part in the heat transfer in the bundle. The overall effect of these limitations is the actual thermal effectiveness (x) will be lower than the theoretical value, and it will be lower than the values obtained for other types of heat exchangers that do not suffer from these limitations. Typically, thermal effectiveness of a conventional shell and tube type exchanger will be in the range of 60% to 80% The Twisted Tube Heat Exchanger
The Twisted Tube heat exchanger originated in Eastern Europe and became commercially available in Scandinavia in the mid 1980’s. It was developed primarily to
overcome the limitations inherent with conventional shell and tube technology. Applications of Twisted Tube technology were primarily in single phase and condensing duties in pulp and paper and district heating with limited exposure in the process industries. In 1991, Koch licensed the technology and in 1995 subsequently acquired the technology outright.
Construction
The Twisted Tube exchanger consists of a bundle of uniquely formed tubes assembled in a bundle without the use of baffles. The tubes have been subjected to a unique forming process which results in an oval cross section with a superimposed helix
Figure 2. Twisted Tube Heat Exchanger Bundle providing a helical tube-side flow path . The forming process ensures that tube wall thickness remains constant and the material yield point is not exceeded thereby retaining mechanical integrity. The tube ends are round to allow conventional tube to tubesheet joints.
. Tube-side Flow Path
A wide range of tube materials can be used including carbon and stainless steels, Cr-Mo alloys, duplex and super duplex alloys as well as titanium, zirconium and tantalum. Tube sizes may vary from ½ inch to 1 inch.
Tubes are assembled into a bundle on a triangular pitch one row at a time with each tube being turned to align the twists at every plane along the bundle length. This alignment results in tubes contacting adjacent tubes at many points along the length of the tube in the bundle (Fig 4). The completed bundle is then tightly strapped circumferentially to ensure no tube movement and a robust bundle is the end result. Bundles can be constructed with more than 5000 tubes and up to 6 feet in diameter with tube lengths up to 80 feet.. Tube Alignment and Support. Completed Twisted Tube Bundle
The shell-side flow path is complex and predominantly axial in nature. Typically, the shell side flow area is approximately equal to the tube side flow area. The bundle is often shrouded to ensure shell side flow remains in the bundle and minimizes bypassing. Paths are available to allow the fluid to flow into and out of the bundle at each end. When high inlet and outlet velocities must be avoided, “vapor belts” may be used as with conventional designs. The Twisted Tube design imparts a swirl flow to the tube-side fluid enhancing the tube-side heat transfer coefficient.
Shell-side Interrupted Swirl Flow
Advantages
Thermal and Hydraulic Performance Elimination of the shell-side back and forth flow path with a more unidirectional flow yields a much higher heat transfer coefficient per unit of pressure drop. Typically, heat transfer coefficients are 40% higher for the same pressure drop or, conversely, pressure drops are halved for the same heat transfer coefficient. Moreover, the tube-side swirl induced flow enhances the coefficients by an amount similar to that of twisted tape or turbulator inserts in a plain round tube. The overall effect of this is a substantial reduction of heat transfer area for a twisted tube exchanger compared with a conventional exchanger for the same duty. Alternatively, significant improvements in the performance of an existing exchanger can be achieved by replacing a conventional bundle with a Twisted Tube bundle.
Higher Thermal Effectiveness The closer approach to pure plug flow on the shell-side means that designs achieving higher thermal effectiveness, more typical of plate type exchangers, are possible with Twisted Tube exchangers
Lower Fouling and Cleanability The elimination of dead spots on the shell-side and the increased turbulence, both on the shell-side and the tube-side results in reduced fouling. Particulate fouling is reduced by the scouring action. Other types of fouling such as scaling and chemical reaction products are prevented by the removal of hot spots. Fouling characteristics are therefore, more typical of those found in plate exchangers rather than shell and tube type exchangers. The lower shell side pressure drop for a given flow means that higher velocities are possible, thereby reducing clogging and plugging with fibrous materials. Should fouling occur, the twist alignment in the twisted tube exchanger provides cleaning lanes even though the bundle is constructed using triangular pitch tube layout. Hence, the cleanability of a conventional square pitch layout is combined with heat transfer area density of a triangular layout.
Vibration Elimination Flow induced vibration can occur in conventional exchangers although special precautions such as “no tubes in window” are available to overcome the problem by providing more tube support. The most damaging vibration arises from fluid-elastic instability that can lead to damage within a few hours of operation. The possibility of such vibration in twisted tube exchangers is completely eliminated by axial flow and because the tubes are supported approximately every two inches along the tube length. Clearly, there is some cross-flow at the inlet and outlet regions but good tube support effectively mitigates this potential for failure. Further, the cleaning lanes provide additional smooth paths with a flow entering and exiting the bundle.
Codes and MembershipsTwisted tube heat exchangers are manufactured to most codes including A D Merkblatter, ASME, B,BS, CODAP, HPGCL, ISPSEL, STOOMWEZEN, and TEMA. Brown Fintube is a member of ASM,ASME, AWS, AQS, HTFS, HTRI, ILTA, NACE, and SME, and manufactures Twisted Tubeexchangers in Houston TX, Luxembourg and in Asia through strategic alliance.
Applications Over 400 Twisted Tube heat exchangers have been designed, built and delivered. A partial list of applications shows a Twisted Tube exchanger bundle being installed in an existing shell in a North American facility. Table 2 contains a comparison of Twisted Tube exchangers and conventional shell and tube exchangers for actual applications including heat transfer surface area and cost savings. Data presented in table 2 are for units constructed with carbon steel, however, in general, in the correct application, cost savings through the use of twisted tube will vary directly with the material cost and the surface area of the heat exchanger. Stated differently, greater savings can be realized as the cost of the material increases. Installation of Twisted Tube Bundle Table I. Applications of Twisted Tube Heat Exchangers
Industry Application
Chemical Petroleum
Pulp & Paper
Power Steel
Mining / Mineral Processing District Heating
Sulfuric acid cooling Ammonia preheating Hydrogen peroxide heating / cooling High pressure gas heating / cooling Crude oil heating Bitumen heating LNG heating Black liquor heating / cooling White water cooling Oil heating / cooling Effluent cooling Turbine steam condensing Boiler feed water heating Lube oil cooling Quench oil cooling Compressed gas cooling Lube oil cooling Liquor cooling Effluent cooling Closed loop water heating
Steam heating
Table II. Comparison of Twisted Tube and Conventional Heat Exchangers
Service Feed / Bottoms Lean / Rich Crude Oil MVGO Exchanger DEA Cooler Product Cooler
Shell-side
Fluid Stripped Water Lean DEA Crude Oil MVGO Product Temp In/Out deg F 250 / 138 244 / 134 122 / 97 260 / 180
Tube-side
Fluid Sour Water Rich DEA Sour Water Water Temp In/Out deg F 100/201 97 / 200 64 / 73 125 / 174
Surface Area Conv / Twisted Conv / Twisted Conv / Twisted Conv / Twisted Square feet 9612 / 4746 1151 / 764 8966 / 5511 2163 / 1097
Cost Conv / Twisted Conv / Twisted Conv / Twisted Conv / Twisted $, 000 $130 / $90 $35 / $25 $215 / $170 $40 / $30
CONCLUSIONS
The construction, thermal characteristics, performance, and use of Twisted Tube type heat exchangers have been reviewed. It has been shown that this type of exchanger offers a number of advantages over the conventional shell and tube exchanger with segmental baffles. In suitable applications, Twisted Tube heat exchangers offers superior economic performance as defined by cost per unit heat load when compared to the alternative of conventional shell and tube type equipment.
"Saudi King: 'We will pump more oil'
Claiming a quarter of the world's proven oil reserves and some of its lowest production costs, Saudi Arabia was producing around 9.2 million barrels per day (1.46×106 m3/d) of oil at the beginning of 2008
According to British Petroleum Statistical Review of World Energy, as of 2007 Saudi Arabia reported it had 264 billion barrels (42×109 m3) of estimated oil reserves, around 21% of conventional world oil reserves.
Since Saudi Arabia produced about 3.2 billion barrels (510×106 m3) of oil in 2006, this would give it over 80 years of reserves at current rates of production.
Although Saudi Arabia has around 80 oil and gas fields, more than half of its oil reserves are contained in only eight fields, and more than half its production comes from one field, the Ghawar field.The raw data are not available to outside scrutiny.
A dissenting opinion regarding Saudi oil reserves came from Matthew Simmons who claimed in his 2005 book "Twilight in the Desert" that Saudi Arabia's oil production faces near term decline, and that it will not be able to consistently produce more than current levels.
In addition to his belief that the Saudi fields have hit their peak, Simmons also argues that the Saudis may have irretrievably damaged their large oil fields by overpumping salt water into the fields in an effort to maintain the fields' pressure and thus make the oil easier to extract.
Since 1982 the Saudis have withheld their well data and any detailed data on their reserves, giving outside experts no way to verify the overall size of Saudi reserves and output. After US President Bush asked the Saudis to raise production on a visit to Saudi Arabia in January 2008, and they declined, Bush questioned whether they had the ability to raise production any more. In the summer of 2008, Saudi Arabia announced an increase in planned production of 500,000 barrels per day.Penketh, Anne.
According to British Petroleum Statistical Review of World Energy, as of 2007 Saudi Arabia reported it had 264 billion barrels (42×109 m3) of estimated oil reserves, around 21% of conventional world oil reserves.
Since Saudi Arabia produced about 3.2 billion barrels (510×106 m3) of oil in 2006, this would give it over 80 years of reserves at current rates of production.
Although Saudi Arabia has around 80 oil and gas fields, more than half of its oil reserves are contained in only eight fields, and more than half its production comes from one field, the Ghawar field.The raw data are not available to outside scrutiny.
A dissenting opinion regarding Saudi oil reserves came from Matthew Simmons who claimed in his 2005 book "Twilight in the Desert" that Saudi Arabia's oil production faces near term decline, and that it will not be able to consistently produce more than current levels.
In addition to his belief that the Saudi fields have hit their peak, Simmons also argues that the Saudis may have irretrievably damaged their large oil fields by overpumping salt water into the fields in an effort to maintain the fields' pressure and thus make the oil easier to extract.
Since 1982 the Saudis have withheld their well data and any detailed data on their reserves, giving outside experts no way to verify the overall size of Saudi reserves and output. After US President Bush asked the Saudis to raise production on a visit to Saudi Arabia in January 2008, and they declined, Bush questioned whether they had the ability to raise production any more. In the summer of 2008, Saudi Arabia announced an increase in planned production of 500,000 barrels per day.Penketh, Anne.
Arctic holds 90 billion barrels of oil: Arshad Azad
The area north of the Arctic Circle has an estimated 90 billion barrels of recoverable oil, the US Geological Survey (USGS) has said.
Included in the Artic bonanza is 1,670 trillion cubic feet of natural gas and 44 billion barrels of natural gas liquids, the USGS said in a statement posted on its website.
The Arctic Circle is the name given to the region around the North Pole. It includes the Arctic Ocean, the northern parts of Europe, Asia, North America and the Russian Far East.
The natural resources are distributed in 25 geologically defined areas thought to have potential for petroleum, according to the assessment, which is the first publicly available petroleum resource estimate of the entire area north of the Arctic Circle.
These resources account for about 22 per cent of the undiscovered, technically recoverable resources in the world.
The Arctic itself accounts for about 13 per cent of the undiscovered oil, 30 per cent of the undiscovered natural gas, and 20 per cent of the undiscovered natural gas liquids in the world.
About 84 per cent of the estimated resources are expected to occur offshore.
"Before we can make decisions about our future use of oil and gas and related decisions about protecting endangered species, native communities and the health of our planet, we need to know what's out there," said USGS director Mark Myers.
"With this assessment, we're providing the same information to everyone in the world so that the global community can make those difficult decisions."
Of the estimated total, more than half the undiscovered oil resources are estimated to occur in three geologic provinces - Arctic Alaska, the Amerasia Basin, and the East Greenland Rift Basins.
On an oil-equivalency basis, undiscovered natural gas is estimated to be three times more abundant than oil in the Arctic. More than 70 per cent of the undiscovered natural gas is estimated to occur in three provinces - the West Siberian Basin, the East Barents Basins, and Arctic Alaska, the assessment shows.
Till now, exploration for petroleum has already resulted in the discovery of more than 400 oil and gas fields north of the Arctic Circle.
These fields account for approximately 40 billion barrels of oil, more than 1,100 trillion cubic feet of gas, and 8.5 billion barrels of natural gas liquids.
Included in the Artic bonanza is 1,670 trillion cubic feet of natural gas and 44 billion barrels of natural gas liquids, the USGS said in a statement posted on its website.
The Arctic Circle is the name given to the region around the North Pole. It includes the Arctic Ocean, the northern parts of Europe, Asia, North America and the Russian Far East.
The natural resources are distributed in 25 geologically defined areas thought to have potential for petroleum, according to the assessment, which is the first publicly available petroleum resource estimate of the entire area north of the Arctic Circle.
These resources account for about 22 per cent of the undiscovered, technically recoverable resources in the world.
The Arctic itself accounts for about 13 per cent of the undiscovered oil, 30 per cent of the undiscovered natural gas, and 20 per cent of the undiscovered natural gas liquids in the world.
About 84 per cent of the estimated resources are expected to occur offshore.
"Before we can make decisions about our future use of oil and gas and related decisions about protecting endangered species, native communities and the health of our planet, we need to know what's out there," said USGS director Mark Myers.
"With this assessment, we're providing the same information to everyone in the world so that the global community can make those difficult decisions."
Of the estimated total, more than half the undiscovered oil resources are estimated to occur in three geologic provinces - Arctic Alaska, the Amerasia Basin, and the East Greenland Rift Basins.
On an oil-equivalency basis, undiscovered natural gas is estimated to be three times more abundant than oil in the Arctic. More than 70 per cent of the undiscovered natural gas is estimated to occur in three provinces - the West Siberian Basin, the East Barents Basins, and Arctic Alaska, the assessment shows.
Till now, exploration for petroleum has already resulted in the discovery of more than 400 oil and gas fields north of the Arctic Circle.
These fields account for approximately 40 billion barrels of oil, more than 1,100 trillion cubic feet of gas, and 8.5 billion barrels of natural gas liquids.
Tuesday, July 15, 2008
CHEMICAL CLEANING SERVICES
In today’s industrial environment, maintenance & energy cost form a large part of the operating cost. In case downtime and/or equipment design does not permit mechanical cleaning the most cost-effective solution is Chemical Cleaning.
PSC/OZEST’s key is of providing quality chemical cleaning rest in the engineered selection process. We have the largest variety of solvent systems, including chelants, organic solvents, inhibitors, alkaline cleaners, organic acid emulsions, mineral acids, and detergents from which to develop cost-effective chemical cleaning processes.
Typical Applications:
■ Boilers
■ Piping
■ Heat Exchangers
■ Evaporators
■ Cooling Water Systems & Towers
■ Reactor Jackets
■ Process Vessels
Metallurgies & Others Handled
■ Admiralty Brass
■ Copper
■ Carbon Steel
■ Austenitic Stainless Steels (300 Series)
■ Martensitic Stainless Steels (400 Series)
■ Inconel
■ Monel
■ Titanium
■ Zirconium
■ Borosilicate Glass
PSC/OZEST is fully equipped to handle all your chemical cleaning needs at a short notice with Circulation Pumps rated from 400 – 1500 gpm @ up to 150 psi; Holding Tanks from 1,000 – 50,000 gallon capacity; Hypalon Steel Braided Hoses, On-Site Laboratory Services.
Chemical Cleaning is proven, efficient & widely accepted method for removal of deposits formed in various refineries and petrochemical plants equipment.
There are two main types of acids used in dissolving contaminants or scales:
Mineral Acids
■ Hydrochloric
■ Sulfamic Acid
■ Nitric Acid
■ Phosphoric Acid
■ Sulfuric Acid
Organic Acids
■ Citric Acid
■ Ammoniated Citric Acid
■ Oxalic Acid
■ Glacial Acetic Acid
During the chemical cleaning Inhibitors are used. The inhibitors form film-on-surface of metal in order to protect parent metal from possible acid attack. Inhibitors do not change the rate of reaction of acid on the scale; they inhibit the metal from reacting with the acid. Different types of inhibitors are used in the industry based on the acid selection.
Advantages of Chemical Cleaning
■ It can be performed on site without disassembling & moving equipment, saving enormous time, labor & associated costs.
■ It eliminates the need for physical entry of personnel thus offering a much safer alternative.
■ It conditions the process surface to reduce future fouling.
■ It can handle systems which are difficult to reach by other conventional cleaning methods such as hydro- jetting.
PSC/OZEST’s key is of providing quality chemical cleaning rest in the engineered selection process. We have the largest variety of solvent systems, including chelants, organic solvents, inhibitors, alkaline cleaners, organic acid emulsions, mineral acids, and detergents from which to develop cost-effective chemical cleaning processes.
Typical Applications:
■ Boilers
■ Piping
■ Heat Exchangers
■ Evaporators
■ Cooling Water Systems & Towers
■ Reactor Jackets
■ Process Vessels
Metallurgies & Others Handled
■ Admiralty Brass
■ Copper
■ Carbon Steel
■ Austenitic Stainless Steels (300 Series)
■ Martensitic Stainless Steels (400 Series)
■ Inconel
■ Monel
■ Titanium
■ Zirconium
■ Borosilicate Glass
PSC/OZEST is fully equipped to handle all your chemical cleaning needs at a short notice with Circulation Pumps rated from 400 – 1500 gpm @ up to 150 psi; Holding Tanks from 1,000 – 50,000 gallon capacity; Hypalon Steel Braided Hoses, On-Site Laboratory Services.
Chemical Cleaning is proven, efficient & widely accepted method for removal of deposits formed in various refineries and petrochemical plants equipment.
There are two main types of acids used in dissolving contaminants or scales:
Mineral Acids
■ Hydrochloric
■ Sulfamic Acid
■ Nitric Acid
■ Phosphoric Acid
■ Sulfuric Acid
Organic Acids
■ Citric Acid
■ Ammoniated Citric Acid
■ Oxalic Acid
■ Glacial Acetic Acid
During the chemical cleaning Inhibitors are used. The inhibitors form film-on-surface of metal in order to protect parent metal from possible acid attack. Inhibitors do not change the rate of reaction of acid on the scale; they inhibit the metal from reacting with the acid. Different types of inhibitors are used in the industry based on the acid selection.
Advantages of Chemical Cleaning
■ It can be performed on site without disassembling & moving equipment, saving enormous time, labor & associated costs.
■ It eliminates the need for physical entry of personnel thus offering a much safer alternative.
■ It conditions the process surface to reduce future fouling.
■ It can handle systems which are difficult to reach by other conventional cleaning methods such as hydro- jetting.
MODERN TECHNOLOGIES OF BUNDLE PULLING
Bundle Pulling
The Truck Mounted Bundle Puller (TMBP) can be quickly mobilized to the site and is a fully self-contained bundle extractor to pull and push back horizontal tube bundles which are located at a height between 680 and 6700 mm and with a maximum weight of 15 tons.
Due to its unique and patented design, this machine can also be used to transport the bundles to the cleaning slab. Therefore it is highly appreciated in all the refineries and in the petrochemical sector.
The main advantage is that during the pulling/pushing operation you do not need a crane any more, which will reduce your cost and bring your downtime back to a minimum!
Less organization is needed!
The truck is allowed to drive on the public road, therefore making it a versatile and efficient tool. Even in a difficult to reach place with a crane, e.g. when there is a pipe frame above the heat exchanger, the Truck Mounted Bundle Puller can still do the job.
Once the extractor is in position and the butt plates are positioned against the shell flange, the extractor can exert a force of 50,000 Kg, enough to extract even the most obstinate bundle. After the initial break out, the hydraulic pulling car will be hooked to the pipe plate and the extractor can pull out the bundle in one continuous stroke. Once the bundle is resting on the truck, it can be transported to the cleaning slab and can be off loaded by crane.
In case the Truck Mounted Bundle Puller cannot be used PSC/OZEST can provide an Aerial Mounted Bundle Puller.
The hydraulic tube bundle extractor is a self-contained unit, which is easily lifted into position by one crane. Once in position, and clamped to the shell flange of an exchanger, the extractor can exert a persuasive force of 50,000 kgf, enough to break out even the most obstinate tube bundle.
PSC OZEST Aerial Mounted Bundle Puller is 8.000 meters long and weighs 7 ton. It is suitable to use for tube bundles with a maximum diameter of 2.000 meters; length of 8.000 meters and weight of up to 45 ton.(for tube bundles with larger dimensions additional equipment / accessories are to be added).
The Truck Mounted Bundle Puller (TMBP) can be quickly mobilized to the site and is a fully self-contained bundle extractor to pull and push back horizontal tube bundles which are located at a height between 680 and 6700 mm and with a maximum weight of 15 tons.
Due to its unique and patented design, this machine can also be used to transport the bundles to the cleaning slab. Therefore it is highly appreciated in all the refineries and in the petrochemical sector.
The main advantage is that during the pulling/pushing operation you do not need a crane any more, which will reduce your cost and bring your downtime back to a minimum!
Less organization is needed!
The truck is allowed to drive on the public road, therefore making it a versatile and efficient tool. Even in a difficult to reach place with a crane, e.g. when there is a pipe frame above the heat exchanger, the Truck Mounted Bundle Puller can still do the job.
Once the extractor is in position and the butt plates are positioned against the shell flange, the extractor can exert a force of 50,000 Kg, enough to extract even the most obstinate bundle. After the initial break out, the hydraulic pulling car will be hooked to the pipe plate and the extractor can pull out the bundle in one continuous stroke. Once the bundle is resting on the truck, it can be transported to the cleaning slab and can be off loaded by crane.
In case the Truck Mounted Bundle Puller cannot be used PSC/OZEST can provide an Aerial Mounted Bundle Puller.
The hydraulic tube bundle extractor is a self-contained unit, which is easily lifted into position by one crane. Once in position, and clamped to the shell flange of an exchanger, the extractor can exert a persuasive force of 50,000 kgf, enough to break out even the most obstinate tube bundle.
PSC OZEST Aerial Mounted Bundle Puller is 8.000 meters long and weighs 7 ton. It is suitable to use for tube bundles with a maximum diameter of 2.000 meters; length of 8.000 meters and weight of up to 45 ton.(for tube bundles with larger dimensions additional equipment / accessories are to be added).
DECONTAMINATION SPECIALIST
Chemical Decontamination
With PSC OZEST Life Guard™ decontamination programs, benzene and other hazards associated with refinery and petrochemical processing can be eliminated in a fraction of the time normally associated with a shutdown. PSC OZEST provides technical refinery expertise to enhance our turnkey service and to insure that every detail is properly addressed. The processes apply to crude units, FCCU units, lube oil plants, ethylene and butadiene plants as well. Our programs combine unique, environmentally safe chemical products with sate-of-the-art mobile pump and filtration systems. Furthermore, we can customize the service for various plant equipment including refinery distillation and fractionation towers, accumulators, drums, reactors and exchangers. It also safely removes Pyrophoric Iron Sulfides and residual H2S using second stage process that takes only 4 – 6 hours in most cases.
The Life guard chemical was developed and patented by PSC.
In general the client will determine what equipment within the unit is to be decontaminated. PSC OZEST will design a detailed procedure with regards to the most cost effective circulation loops. Upon approval of the detailed procedure PSC OZEST ties in the pump/filtration equipment and other accessories. A special formulated decontaminating solution is circulated for several hours at rates up to 2,000 gpm, filtering out solids down to 40 microns, if necessary.The emulsion that is formed is then broken down in a fracturing tank using a demulsifier to allow recovery of the hydrocarbon that is removed from the process equipment. The subsequent aqueous phase is discharged to the plant’s API or waste treatment facility. PSC OZEST closed loop system Life Guard™ makes EPA and OHSA compliance much easier to achieve.The major benefits are:
■ Zero LEL
■ Zero H2S
■ Less than 0.5 ppm Benzene
■ No steaming out or Nitrogen purging required
■ Less heat exchangers to be pulled during the shutdown, if included in the process.
■ Time saving.
■ Pyrophoric materials will be oxidized
■ Partial scales removal (when scale is bounded with hydrocarbon)
The Life Guard is
■ Neutral
■ Biodegradable
■ Has no impact on any material
■ Very powerful emulsifier
■ Can be easily Broken back into Oil & Water
■ More than 2000 projects worldwide including Saudi Arabia
■ Approved by CSDC ( Aramco ) & used in Ras Tanurah Ref, Riyadh Ref, Jeddah Ref, Yanbu Ref, Lub Ref, Sam Ref , Sas Ref, etc.
PSC OZEST offer more than a chemical-cleaning vendor does. We take a comprehensive approach, as if the refinery belongs to us. OZEST walks every job and with the continuous support of PSC designs the most efficient circulation loops to facilitate the decontamination of entire crude units and coker units. OZEST’s customers offer the best support to the effectiveness of our decontamination processes.
With PSC OZEST Life Guard™ decontamination programs, benzene and other hazards associated with refinery and petrochemical processing can be eliminated in a fraction of the time normally associated with a shutdown. PSC OZEST provides technical refinery expertise to enhance our turnkey service and to insure that every detail is properly addressed. The processes apply to crude units, FCCU units, lube oil plants, ethylene and butadiene plants as well. Our programs combine unique, environmentally safe chemical products with sate-of-the-art mobile pump and filtration systems. Furthermore, we can customize the service for various plant equipment including refinery distillation and fractionation towers, accumulators, drums, reactors and exchangers. It also safely removes Pyrophoric Iron Sulfides and residual H2S using second stage process that takes only 4 – 6 hours in most cases.
The Life guard chemical was developed and patented by PSC.
In general the client will determine what equipment within the unit is to be decontaminated. PSC OZEST will design a detailed procedure with regards to the most cost effective circulation loops. Upon approval of the detailed procedure PSC OZEST ties in the pump/filtration equipment and other accessories. A special formulated decontaminating solution is circulated for several hours at rates up to 2,000 gpm, filtering out solids down to 40 microns, if necessary.The emulsion that is formed is then broken down in a fracturing tank using a demulsifier to allow recovery of the hydrocarbon that is removed from the process equipment. The subsequent aqueous phase is discharged to the plant’s API or waste treatment facility. PSC OZEST closed loop system Life Guard™ makes EPA and OHSA compliance much easier to achieve.The major benefits are:
■ Zero LEL
■ Zero H2S
■ Less than 0.5 ppm Benzene
■ No steaming out or Nitrogen purging required
■ Less heat exchangers to be pulled during the shutdown, if included in the process.
■ Time saving.
■ Pyrophoric materials will be oxidized
■ Partial scales removal (when scale is bounded with hydrocarbon)
The Life Guard is
■ Neutral
■ Biodegradable
■ Has no impact on any material
■ Very powerful emulsifier
■ Can be easily Broken back into Oil & Water
■ More than 2000 projects worldwide including Saudi Arabia
■ Approved by CSDC ( Aramco ) & used in Ras Tanurah Ref, Riyadh Ref, Jeddah Ref, Yanbu Ref, Lub Ref, Sam Ref , Sas Ref, etc.
PSC OZEST offer more than a chemical-cleaning vendor does. We take a comprehensive approach, as if the refinery belongs to us. OZEST walks every job and with the continuous support of PSC designs the most efficient circulation loops to facilitate the decontamination of entire crude units and coker units. OZEST’s customers offer the best support to the effectiveness of our decontamination processes.
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