Chemicals for boilers and steam
Internal or chemical treatments
The types of products used in boilers are:
- Dissolved oxygen scavengers. Its function is to remove the dissolved oxygen: sulfites, hydrazine, carbohidracina, DEHA, etc ...
- Neutralizing amines. Its function is to remove carbon dioxide: Morpholine, cyclohexylamine, DEAE, pH control, ...
- Antifouling and dispersing. Its function is to control the deposits: phosphates, phosphonates, dispersants, ...
Oxygen scavengers
Its function is to eliminate the residual chemically dissolved oxygen in the feedwater degassing after mechanical (thermal ...). Its use prevents corrosion by oxygen in the form of "pitting" in the boiler and the water supply system (economizer).
In aqueous medium, the iron to ferrous hydroxide is oxidized by the action of hydroxyl ion. This, by the action of oxygen in solution passes into ferric hydroxide (red color), which involves corrosion. At elevated temperatures the ferrous hydroxide is converted to a dense layer for protection called magnetite black color, which protects the metal from the water and oxygen.
As scavengers of oxygen products are:
- Sodium sulfite: reaction with oxygen to form sodium sulfate. Continuous should be dosed into the feed water of the boiler (degassing tank), controlling the existence of residual to remove oxygen. The formation of sodium sulphate increased dissolved solids and high pressure (> 50 bar) is decomposed into sulfur dioxide.? The rate of reaction between sodium sulfite and oxygen is rapid. However at low temperatures is necessary to use trace amounts of cobalt sulfate to accelerate the reaction (catalyst). For pressures above 80 psi is not recommended sodium sulfite. Catalyzed sodium sulphite (cobalt sulfate) reacts much faster than the non-catalyzed and it is advisable dosed separately in the degassing tank. Adding the stoichiometric ratio is from 7.88 ppm of sodium sulfite per 1 ppm of oxygen, but is better to use the ratio 10:1.
- Hydrazine: Replaced sulphite in high pressure systems. The main advantage is that no solids in the boiler increases, but the problem is in the list of carcinogens (OSHA PEL 0.1 ppm, SARA Title reporting IIISection 313) and as such requires special handling. The current use is limited to large steam generating systems (power plants). Hydrazine (35%) is fed directly to the feed water at a rate of 0.05 to 0.10 ppm. At temperatures below 150 ° C the reaction is very slow, the use of hydroquinone as catalyst increases the reaction rate from 10 to 100 times. At temperatures above 400 ° C hydrazine begins to decompose into ammonia, which is corrosive to copper and other alloys.
- Carbohidracina: The replacement for hydrazine and acts like it but do not have the dangers related to it. As hydrazine, does not increase the solids in the boiler. But it has the inconvenientoe the reaction with oxygen produces 0.7 ppm carbon dioxide for each ppm of oxygen, which must be taken into account in the calculation of neutralizing amine needs. Using the stoichiometry is 1.4 ppm per carbohidracina ppm of dissolved oxygen, and is metered directly into the system as a solution 6.5%. The recommended dose in the feed water is sufficient to control from 0.05 to 0.3 ppm as hydrazine, since it is in this inside the boiler.
- Erythorbic acid: An organic acid, isomer of Vitamin C. For this is recognized by the FDA as GRAS product for applications where steam is in contact with food. The 10% solution of erythorbic acid has a pH of 2.1. The product is formulated at pH 5.5 with neutralizing amines or ammonia. Is catalyzed with copper sulphate (1:50).
- Methylethylketone (MEKO): A dissolved oxygen reducing having a distribution ratio higher than DEHA and funcina better than this in long condensate systems. The distribution ratio is between the DEAE and cyclohexylamine. The Methyl reacts faster than any other substitute for sodium sulfite. 5.4 ppm are required MEKO for each ppm of dissolved oxygen. The MEKO does not have the capabilities ismas passivating that DEHA, so its use is not so advised.
- Hydroquinone: It has fast reaction speed, even in cold water. It can be used alone as deoxygenating. commonly used as a catalyst for Hydrazine DEHA and carbohydrazide, even for low pressure applications. In mixed-bed demineralizers can produce blackening of the resins due to the rapid reduction reaction. Hydroquinone is stable up to 275 ° C, the final decomposition generates carbon dioxide. Required stoichiometry is 6.9 ppm of hydroquinone per 1 ppm oxygen.
- N, N'-diethylhydroxylamine (DEHA): deoxygenating volatile passive metal surfaces of the boiler and condensate lines. It is a strong reductant capable of reversing the red ferric oxide to magnetite keeping waste in the boiler between 150 and 300 ppb. Catalyzed with hydroquinone acts at low temperatures. The stoichiometry is 1.24 ppm of DEHA per 1 ppm of dissolved oxygen, but better results are obtained with a 3:1 ratio. In its reaction with oxygen and acetic acid formed can be decomposed even carbon dioxide, which requires an additional consumption of neutralizing amine. Decomposes into ammonia from 280 ° C versus 168 ° C for hydrazine. DEHA analysis is performed using a kit based on the reduction of ferric ion to ferrous.
Neutralizing amines
Carbon dioxide dissolved in water (especially if there is an adequate degassing or only decalcified water is thus retaining the alkalinity in the boiler leading to decomposition of carbonates and bicarbonates in carbon dioxide) for steam and by condensing passes carbonic acid corrosion resulting acidic return lines and contaminating the condensate with dissolved iron, it is therefore necessary to add a neutralizing amine to maintain a pH = 8.3 to 8.5 minimum. At a dose of 2-3 ppm of product should be sufficient neutralizing the amount of amine added.
Its function is the chemical removal of carbon dioxide in the water supply after the degassing mechanically or by decomposition of carbonates and bicarbonates. Its use prevents corrosion by low pH acid condensate lines.
Neutralizing the amine forms a carbonate by reacting with the carbonic acid from the carbon dioxide vapor. The neutralizing amine also raises the pH of the condensate by formation of hydroxyls. The degasser carbonate stripping occurs and allows the regeneration of the amine.
Neutralizing capacity of various amines
Neutralizing amines are the carbonates are also dioxide ammonium ions and hydroxide. The distribution ratio (DR) of the amine from the vapor phase and the amine in the liquid must be controlled. Thus we have the pH and temperature influence DR.
We have the following circumstances:
- RD> 1 means that the amine goes further with steam
- RD <1 means that the condensate goes faster
This results in a loss of volatile amine in the degasser. This loss will depend on the amine used:
- Morpholine: loss of 1.0%
- DEAE: loss of 3.0%
- >Cyclohexylamine: loss of 1.7%
FDA limits for various amines
Each amine has a limit FDA:
- Morpholine 10.0 ppm
- DEAE: 15.0 ppm
- Cyclohexylamine at 10.0 ppm
- Ammonia: No limit
- Octadecylamine 3.0 ppm
- Amina soybean: 0.0 ppm
- The Amina Total can not exceed 25 ppm in the steam and each amine can not exceed their individual limit.
And the choice of the amine should be performed based on the distribution ratio distridución:
- Cyclohexylamine, steam piping long distances.
- Diethylaminoethanol, steam pipe runs between.
- Morpholine, steam pipe with short routes.
- Complex systems is desirable for a mixture of amines.
Antifouling and dispersing
Its main function is the chemical precipitation and ion chelation, inhibition and / or dispersion to prevent scale formation from dissolved salts in the boiler water. Its use prevents scaling, loss of energy efficiency, etc..
The main products used are: - Phosphates
- Chelating
- Phosphonates
- Dispersants
Chemicals for reverse osmosis
Chemical treatments
The chemicals for the control and maintenance of reverse osmosis having in mind the following objectives:
- Minimize scaling and fouling of the membranes.
- Having a low operating cost compared to other existing products.
- Providing easy and safe product handling with excellent pourability.
These products are divided into three groups:
- Antifouling
- Cleaning agents
- Biocides
Anti-fouling reverse osmosis
The antifouling reverse osmosis equipment used to prevent clogging of the membranes by deposition of crystals of calcium, magnesium and silica on the external surface in the pores or between them, this contamination leads to increased accumulation of precipitates in the membranes, thus increasing the required pressure, are increased energy costs, cleaning operations and limited useful life of the membranes.
The use of the antifouling series ECOTEC, OSMOTAX and OSMOTEC and membranes have been developed for reverse osmosis and nanofiltration. The main features are as follows:
- It is highly effective against all the most common scale, such as carbonates and sulfates of barium and strontium and calcium fluoride.
- Inhibits deposits of silica, iron and aluminum.
- Compatible with all membrane types.
- Reduces or even eliminates the need for acid.
- Allows systems to operate at the highest recovery rates possible.
For dosing this must be continuous to the feed water. It can be dosed from its pure form or diluted. For the optimal dosage has collected data sheets for our technical specialists can advise on which product to use in each case.
Cleaning Agents
When a blockage of the membranes by pollution is to analyze the problem and define an action procedure to determine the type of cleaning that has to do with the characteristics of the deposition, using specific products according to the source is organic or inorganic.
The series of basic cleaning agents ECOMET, OSMOTEC OSMOTAX and chelating agents are mixed with a nonionic surfactant organic material removed from the membranes and also has good effectiveness for removing iron deposits and various deposits.
The series of ECOMET, OSMOTEC and OSMOTAX acidic cleaning agents, are cleaners agents developed and inorganic scale and iron incrustations.
Biocides
The biocides are used to avoid the formation of biofilm, when determined that the water supply exceeds the recommended microbial population is necessary to act to reduce product in an effective microorganisms, therefore depending on the characteristics of waters, we select the most appropriate biocide.
The series of biocides OSMOCIDE are broad spectrum biocides membranes used for reverse osmosis and nanofiltration. They can be used offline as biological cleaner and can be used as a pretreatment for the prevention of biofilm in the pipes, sledgehammers and membranes.
Chemicals for refrigeration circuits
Chemical treatments
The goal of each treatment program should be doubled, keeping the surface of metals without corrosion or deposits and achieve this with minimal cost. Today more than ever the costs of corrosion and deposits in cooling water systems, are becoming more critical. These costs include loss of effectiveness due to poor heat transfer, unplanned shutdowns and capital costs to replace the facility.
Each system has different needs for treatment of water depending on the quality of the metallurgy of the system, characteristics of water or restrictions of purging, so that a same product is not practical for all plants. To meet the different needs has developed a complete range of corrosion inhibitors, scale and multifunctional, biocides, etc ...
Corrosion inhibitors for cooling circuits
The application of corrosion inhibitors in cooling systems is key in a water treatment program. As the corrosion of the metallurgy of the system may create serious performance problems and, ultimately, well, could cause the computer to malfunction, it is important to properly select and apply corrosion inhibitors applied. The type of cooling system, water features, operating conditions and metallurgy of the system are all atener variables into account when determining what type of inhibitor to give us the best results at a better cost.
Scale inhibitors for cooling circuits
The application of anti-fouling in cooling systems have been studied specifically to avoid the formation of the crystal, distorting the structure of this and favoring the presence of ions above the solubility "treshold effect". Incrustation inhibitors have been so designed to prevent the formation of specific elements such as dirty water iron oxide or calcium crusts. The removal of these sediments as problematic not only ensures better heat transfer and maximum water flow but also provides clean metal surfaces, thereby favoring formation of precipitates inhibiting layer.
Biocides for cooling circuits
Microbiological monitoring is essential to avoid problems of bacterial contamination in systems that may affect public health and performance of the equipment, so we have developed a full range of registered biocidal products necessary for the prevention of legionellosis, and other diseases covered by extensive legislation.
Biodispersants and cleaners
The presence of organic and inorganic deposits reduce the flow rate of industrial cooling systems, resulting in costly downtime and favoring the microbiological contamination of the equipment. It is necessary to remove them through specific products that allow us to maintain the facility in perfect condition and cleanliness.
Defoamers
The range of defoamers allows us to control the presence of foam, reducing the surface tension and avoiding problems of carryover of solids suspended in the circuits and heat exchangers.
