Boilers filming inhibitors

There is some disagreement as to the desirable feeding point for film-forming inhibitors. All inhibitor suppliers say that the materials can be fed directly to the steam and condensate systems. Some suppliers recommend adding the inhibitor to the feed water or directly to the boiler and say that the inhibitor will evaporate with the steam and condensate in a thin, continuous film. However, most of the commercially available filming inhibitors are formulated produets, each component having a somewhat different volatihty (and solubility) and, therefore, the preferred point of addition should be the steam header. 

Boilers and steam systems Steel steam lines can be inhibited by the use of a volatile amine-based inhibitor such as ammonia, morpholine or cyclohexylamine introduced with the feedwater. It passes through the boiler and into the steam system, where it neutralizes the acidic conditions in pipework. The inhibitor is chemically consumed and lost by physical means. Film-forming inhibitors such as heterocyclic amines and alkyl sulphonates must be present at levels sufficient to cover the entire steel surface, otherwise localized corrosion will occur on the bare steel. Inhibitor selection must take into account the presence of other materials in the system. Some amine products cause corrosion of copper. If copper is present and at risk of corrosion it can be inhibited by the addition of benzotriazole or tolutriazole at a level appropriate to the system (see also Section 53.3.2). 

Anodic polarization also may occur. Typically, this begins with the formation of a thin, impervious oxide film, chemisorbed at the anode (as on the surface of stainless steels). However, for most metals used in boiler plant systems this chemisorption process must be aided by anodic corrosion inhibitors to reduce corrosion rates to tolerable levels. An example is the application of nitrite-based inhibitors, widely used in HW heating systems. 

When the boiler is placed back online, certain types of anodic inhibitors (which are generally employed to act as polishing treatments in the maintenance program) also may prove beneficial in further strengthening the passive film. 

Although orthophosphates are themselves passivating, anodic inhibitors (and also cathodic inhibitors, forming a calcium phosphate barrier film), the film strength is weak, even in simple HW systems and they are not used for this purpose. Nevertheless, despite the thermal instability of sodium hexametaphosphate and other polyphosphates, phosphates in general have several important properties that make them useful in boiler plant operations. These properties include ... 

To increase equipment reliability and plant efficiency, corrosion inhibitors are used in boiler and cooling water programs to control fouling and deposition on critical heat-transfer surfaces. In cooling systems, corrosion inhibition is commonly achieved through the use of passivators, which encourage the formation of a protective metal oxide film on the metal surface ( 1). ... 

In the absence of solid corrosion products, the corrosion rate can be Urnited by reducing the availability of the cathodic reactant, such as in the removal of oxygen from the water for boilers substituting for the anodic reaction an external current, as in the case of impressed current cathodic protection or inducing artificially the formation of surface films, as in the case of the application of corrosion inhibitors. 

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). 

Uses Dispersant in boiler water treatment mineral scale control aid flocculant and coagulant aid in water and wastewater treatment, sugar processing migration inhibitor for use in continuous dyeing film-former in cosmetics hair spray resin in food-pkg. adhesives in food-contact paper/paperboard... 

Completely soluble in water and brine. Cationic behavior makes it useful for the formulation of corrosion Inhibitors. Film-forming amine. Steam volatile for boiler-condensate corrosion control. Low combining weight makes it an efficient neutralizing amine. 

Vapor-phase inhibitors (VPIs), also called volatile corrosion inhibitors (VCIs), are compounds which are transported in a closed system to the site of corrosion by volatilization from a source. In boilers, volatile basic compounds such as morpholine or octadecylamine are transported with steam to prevent corrosion in condenser tubes by neutralizing acidic carbon dioxide. Corrosion inhibitor compounds vaporize from the paper or film. They are attracted to the charged surface of the metal by virtue of their polar orientation. 

Uses Film-former for corrosion inhibitor formulations, boiler-condensate corrosion control drilling fluid additive neutralizing amine Properties Dk. amber liq. sol. in water and brine 100% cone. 

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