 | THE ADVANTAGE OF THE CHEMICAL PREVENTIVE TREATMENT | |
The combustion of heavy fuels, coals, wood, domestic waste and special waste generates incombustible cinders and/or carbon unburnt clogging the generators heat exchangers: hot water or steam boilers, recovery and other fluid reheating furnaces.
Likewise, lubrication oil leaking out of gas or fuel engines in cogeneration plants is fixed on the exchangers producing hot water or steam.
To eliminate these deposits, it is necessary to use on-load cleaning systems if any, or periodically stop the boilers to clean them up. These operations are expensive: waste energy (steam, compressed air), maintenance of the soot removing equipment, replacement of the eroded tubes but also production losses due to programmed or un-programmed cleaning stoppages.
The Preventive Chemical Treatment is therefore the only way - to compensate the inadequacies, deficiencies or even the lack or on-load cleaning systems,
- to slow down the clogging,
- to make periodical cleaning easier,
- to neutralize the acidity of the deposits.
|
| THE CLOGGING OF THE HEAT EXCHANGERS (fire-side) (côté feu) | |
There are many reasons and one can make a distinction between: the fatal reasons and the accidental ones.
1/ The Fatal reasons
There are many. For instance :
The Fuel composition
The composition of liquid fuels sold in France among others, has changed a lot in the past 25 years. The crude oil refining processes have been greatly improved to extract a greater proportion of white products for which there was a much greater demand.
Supply sources were diversified: the different crude-oils used do not have the same technical specifications: grades in bitumen sulfur or vanadium and sodium can vary from one crude to the other.
To market the overabundant black products, they were mixed with other lighter products.
Despite all precautions taken, these products are more dirtying than before. They can sediment the tanks while reheated, the bitumen clog the filters and the burner-hoses, the vanado-sodic deposits block the gas courses in the super heaters, etc.
|
|
example of the size of the deposits
Supply sources are no longer local but international. While of comparable elementary composition, the burning characteristics of these coals can generate clogging problems that need to be kept under control. This can be time-consuming. Meanwhile the heat exchangers clog-up.
|
|
The obsolescence and aging of the heating equipment.
In 1995, a very serious study published by one of the main control bodies of pressure equipment indicated that 60 % of the number of boilers in France was over 20 years old. Even well maintained, the heating equipment, burners, coal grids, on-load soot removal equipment are less efficient than when they were built.
Clogging of the heat-exchangers is a more frequent occurrence, cleaning less efficient.
Clogging of the heat-exchangers is a more frequent occurrence, cleaning less efficient.
|
Over sizing the energy producing means.
Before leading the operators to consider other new energy producing forms, the reduction of energy needs these last decades first led them to lessen the boilers load. However, the Knowing Man knows that the efficiency of a generator is lesser at 50 % of the nominal than at 80 %, clogging has become larger and faster.
The technology of some generators.
Barring few exceptions, it is exceptional to have smoke-tube boilers running on heavy fuel or coal or recovery boilers equipped with steam or compressed air soot-removers.
Only the high power cogeneration plants equipped with boilers producing high pressure steam can use steam soot-removers if they have the necessary quantity.
The plants producing only hot water are not fitted with any on-load cleaning system: the heat-regenerators must be cleaned off-load under very painful conditions.
|
2/ Accidental reasons
They are frequently due to temporary mechanical deficiencies. Burner wear, coked-up burner-noses, blacking of the air regulators, combustion regulating system, soot-removal equipment, etc.
Load variation too frequent and of a range too wide are often the main reason to a fast clogging.
Repeated damp cleanings can also lead to the forming of deposits, very hard, often acid, that will progressively block the gas courses.
Finally, in cogeneration plants equipped with gas or fuel engines, it is too often the over-consumption of lubricant that will clog the heat-exchangers.
|
|
| THE AIT DRIVEX SOLUTION | |
The Chemical Preventive Treatment developed by AIT DRIVEX over many years will :
- bring back the efficiency to on-load cleaning systems, compressed air or steam soot-removers, vibrators by interposing between the deposits and the tubes a high melting point protecting film keeping the ashes from sticking to the hotter tubes : super heaters, screen tubes,
- destroy the unburnt carbons through oxidation,
- help neutralize the acidity of the deposits.
In some cases, the Chemical Preventive Treatment can compensate the absence of an on-load cleaning system.
|
| THE PROCESS ADVANTAGES | |
AIT DRIVEX offers original reagents :
They are :
Liquid, hence easier to inject in the burner's flame or above a coal-bed or burning waste or to vaporize inside the flue gas.
Safe, because non-flammable and heavy-metal or chlorine free. They do not damage the generators material nor the metal of the tubes or refractors. They do not generate any damaging releases for the environment.
|
|
Efficient. their film-like and residual nature over heat exchangers means a much greater allowance for the loading of generators or the composition particularly in incineration plants.
Several formulas are available. They are adapted to each kind of deposit: unburnt carbons, molten ashes.
|
|
Cost efficient. They are not continuously injected. The regeneration of the reagent plan is possible with just a few daily injections.
The dosage is faibles : minimal: 2 to 3 kilos of product for 10.000kilos of fuel on average.
|
|
|
| GOALS | |
The continuous use of one of the Preventive Treatment reagents thus allows : - to keep the heat-exchangers clean longer, therefore saving fuel,
- a lesser need to remove soot whether with steam or compressed air, reducing the emission of polluting agents (dust, acid fumes) in the atmosphere,
- to space the use of the cleaning systems,
- to space the periodical cleanings and make them easier when necessary.
|
|
 |
 |
|
