Chemical Cleaning of Feedwater Heaters

In a paper delivered before the 1960 meeting of the American Society of Mechanical Engineers(1), the need of preoperational cleaning of the preboiler system of utility boilers was brought into sharp focus for the first time. This viewpoint of the utility operator met with acceptance and today nearly every specification prepared for new boiler installations contains detailed instructions and specific directions to be followed during cleaning of the feedwater system. Other authors(2,3) have dealt at length with the proper care that should be given to the heaters, piping, et cetera during fabrication, shipment and erection. Despite such discussion of the subject, each new installation continues to cause concern as how best to provide cleanliness of the heater train so as to avoid or minimize subsequent contamination of the water/ steam cycle upon start-up. A schematic diagram of the feedwater system and it's relation to the steam generator, the turbines, and the condenser are shown in Figure 1*. The volume of the feedwater system may be in excess of 30,000 gallons. Preoperational cleaning is generally done by circulating hot solutions through the piping system including the heaters. If both the shell and tube sides of the heaters are to be cleaned prior to start-up, considerable savings can be effected by installation of sufficient temporary piping to include both sides in one circuit.