Inhibitors cooling water systems

Cooling water systems are dosed with corrosion inhibitors, polymers to prevent solid deposition, and biocides to prevent the growth of microorganisms. 

Petroleum greases and oils can be excellent corrosion inhibitors on a variety of alloys. The hydrophobic layer produced by oil or grease can prevent water from contacting surfaces and can, therefore, almost eliminate corrosion. Unfortunately, the addition of oil and grease cannot be recommended as a corrosion-reduction measure in cooling water systems for three basic reasons. 

Corrosion inhibitor 1 Bacterial control J Cooling-water system Consumption depends on make-up Chemicals are used to provide adequate reserve... 

Industrial Cooling Water Systems Waters used for recirculating cooling systems can either be scaling or corrosive. Corrosive waters are treated with corrosion inhibitors which require monitoring for overall assessment of the treatment programme. 

Amine salts of ether carboxylates inhibit internal corrosion of oil storage tanks and pipelines [230]. Furthermore it is possible to use ether carboxylates as corrosion and scale inhibitors for industrial recirculating cooling water systems, metalworking fluids, and hydraulic fluids [28,231-233]. 

NOTE Many closed-loop cooling water systems are not, in fact, closed, as they contain open-top, return-water tanks. This provides a continuous source of oxygen from the air into the system, with the result that the risk of corrosion greatly increases. Adequate attention should be paid to countering this risk, perhaps by an improved corrosion-inhibitor treatment or a floating blanket or plastic balls in the water tank (which help to minimize the ingress of air). 

Despite some limitations, the wide range of inhibitor effects of O + P phosphates has meant that this inhibitor group, along with chromates, has been perhaps the most important formulation material employed in cooling water systems. 

Apart from sodium hypochlorite and sodium bromide solutions, almost all other liquid biocides (or biocide intermediates) are nonoxidizer types. Most nonoxidizers are manufactured by specialist chemical companies, who sell these branded products for scores of different sanitizing or disinfection applications, of which cooling water system treatment is only one. These chemicals may be merely renamed (according to subregistration permits) or they may be blended with other biocides or inhibitors to form new and different products with accordingly modified properties. Some biocides may only be available from the primary manufacturer, often as extremely concentrated and hazardous materials. These chemicals will then usually require some form of dilution, stabilization, and quality verification before being incorporated into a service company s product line. 

Downward, Brian L. Failon, Brian K. A New, All Organic High Performance Corrosion Inhibitor for Industrial Cooling Water Systems. Albright Wilson, 1996. 

Bahadur, A., 1993, Chromate substitutes for corrosion inhibitors in cooling water systems. Corrosion Reviews, 11, 105 - 122. 

Continuous ferrous sulphate addition has been used for many years to reduce water side corrosive attack of steam condenser tubes. It is usually applied to once through cooling water systems because of its low cost, to provide an iron-rich protective film on the tube surface. For recirculation systems other more expensive, corrosion inhibitors are generally employed. Two phases of the ferrous sulphate treatment programme may be recognised. The first phase involves the initial laying down of the protective film. The second phase involves the maintenance of the film, which would be otherwise destroyed by the shear effects of flow. 

Fig. 16.3 gives the flow sheet of a cooling water system commonly used in power generation that is also used in the process industries. Chemicals such as acids, biocides, scale and corrosion inhibitors and dispersants are added to control problems of fouling in the recirculating system (described elsewhere in this book). The technique is generally applicable where the make-up water is generally of low hardness and silica and low concentration factors are employed. 

POM. [Climax Perftxnumce] Molybdenum trioxide corrosion inhibitor for cooling water systems. 

Boilers, closed cooling water systems, and other closed circulating fluid systems can be treated with inhibitors with continuous injection. When snch systems are started up after construction or major maintenance, the inhibitor is often injected at higher-than-normal concentration to permit rapid development of protective films (Tang et al. 2012). 

Shibli and Kumary (2004) have once utilized the eco-friendly nature of gluconate compounds when they tested the inhibitive effect of calcium gluconate and molybdate on carbon steel but in cooling water systems. They concluded that a nonlinear relationship existed between the concentrations of the two inhibitors showing a synergistic effect. 

Uses Scale inhibitor for cooling water systems, boilers, and in oil fields to control calcium, barium, magnesium, strontium, and iron scale deposits... 

Uses Corrosion/scale inhibitor in cooling water systems, boiler water systems, oil field inj. systems, sugar mill evaporator systems, reverse osmosis systems, desalination systems in paper/paperboard in contact with dry food... 

Many different corrosive agents can accumulate in a closed cooling water system if the concentration factor is too high. The use of inhibitors, noted above, is a standard technique. Upgrading the materials of construction also can prolong the life of equipment. Parkinson [13], for example, describes the use of a 75-p,m coating of electroless nickel on cooling water pumps. 

Any possible radioactive leakage from the foregoing reactor equipment would be to, and would be confined in, the closed loop cooling water system, which is monitored continuously for radioactivity. A surge tank is used to accommodate system volume swell and shrinkage and to provide a means for adding makeup water and inhibitors. 

Finally, degradation of corrosion inhibitors such as aliphatic amines, nitrite, and phosphate-based corrosion inhibitors may result in a damage of iron and mild steel. This mechanism is frequently found in steel pipes in cooling water systems. It results not only in a higher demand for... 

Cooling water systems are one of the most important fields where synergistic corrosion inhibitor blends are applied for temporary corrosion protection. Several combinations have been developed which are capable of achieving increased protection under various plant operating conditions. Some of the most important synergistic mixtures are chromate-zinc, phosphonate-zinc, polyphosphate-zinc, polyphosphate-chromate, polyphosphate-phosphonate, and ni-trite-phosphonate. 

Corrosion inhibition in recirculated cooling water systems historically depended on the oxidizing inhibitors such as chromates and nitrites. These days are gone since nitrites have been found to be highly conducive to organic growths and chromates have been phased out for environmental toxicity reasons. 

While ferric ion inhibitors are important in many cleaning processes, they are essential to clean open cooling water systems. If the cooling tower in such systems... 

This is an area worthy of further research, as Cu alloys are widely used in recirculating cooling water systems to which corrosion inhibitors are added. 

Corrosion is a serious problem in all cooling water systems. The cooling water may be salt water (35 000 ppm TDS), brackish water (3000-5000 ppm) or fi esh water (<300ppm TDS). Inhibitor treatment is required for heat exchanger and distribution lines. 

It is very rare that a single inhibitor is used in systems such as cooling water systems. More often, a combination of inhibitors (anodic and cathodic) is used to obtain better corrosion protection properties. The blends which are produced by mbdng of multi-inhibitors are called synergistic blends. Examples include chromate-phosphates, polyphosphate-silicate, zinc-tannins, zinc-phosphates. Phosphonates have been used to cathodically protect ferrous materials. Following are the major applications of synergistic blends of inhibitors. 

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