PREOPERATIONAL CHEMICAL CLEANING OF HEAT RECOVERY STEAM GENERATORS

摘要

Combined-cycle power generation has become very popular for utilities wishing to increase their power production capacity. Compared to conventional coal-fired units, combined-cycle plants are less expensive, easier to install, have a higher efficiency, and, at the time of this study, are less subject to environmental regulations. An integral component of a combined-cycle unit is the heat recovery steam generator (HRSG). Although heat fluxes in an HRSG are typically lower than in a standard boiler, water chemistry issues are just as critical. One topic of extensive discussion among power generating personnel is pre-operational chemical cleaning of HRSGs. Pre-operational cleanings are often recommended to remove lubricants, mill scale, weld spatter, and other debris that would otherwise foul the boiler upon start-up. Chemical cleaning of an HRSG is frequently complicated by the physical lay out of the unit, which may include two or even three steam generating circuits. This may require staged or extended cleaning procedures. This report outlines previous experiences with HRSG pre-operational cleanings and it looks at how cleaning procedures may be improved in the future.