Corrosive carbonic acid

Economizers are not usually designed to generate steam, and any deposits found in them therefore are not likely to be a result of carbonic acid corrosion or contamination from steam. Rather, the transport and buildup of corrosion debris within an economizer tends to originate from corrosion processes occurring either in the economizer itself or in some upstream part of the pre-boiler system. Economizer deposits typically develop in the presence of oxygen and possess a high iron content. 

Although the need to properly soften the FW control BW variables such as alkalinity, TDS, and sludge and limit carbonic acid corrosion remains vital, these other problems generally are secondary to effective control over DO. If severe boiler plant damage and system failure are to be avoided, it is necessary to continuously maintain waterside reducing conditions and properly passivated boiler surfaces. 

Corrosive gases including Oxygen Carbon dioxide Results in Oxygen corrosion. Carbonic acid corrosion. Greatly enchanced... 

In lower pressure commercial and industrial boilers, handling and safety are issues of more concern than relative chemical effectiveness, and the fact is that because of such problems, ammonia simply is not used in these smaller plants. Caustic generally provides the necessary FW alkalinity and amines are then employed to overcome the problems of carbonic acid corrosion in the steam-condensate system. 

Condensate lines and vented receivers are vulnerable to oxygen and carbonic acid corrosion. 

Figure 8.6 Venting below the pass partition baffle stops carbonic acid corrosion.

The problem with carbonated steam-gas injection is the carbonic acid corrosion. The surface lines and injection coluinns within the well must be properly protected. 

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