tailieunhanh - Central Boiler Plants Episode 2 Part 2

Tham khảo tài liệu 'central boiler plants episode 2 part 2', kỹ thuật - công nghệ, cơ khí - chế tạo máy phục vụ nhu cầu học tập, nghiên cứu và làm việc hiệu quả | TM 5-650 CHAPTER 4 WATER TREATMENT FOR BOILER PLANTS SECTION I. INTRODUCTION 4-1. OBJECTIVES OF WATER TREATMENT This chapter is an introduction to boiler water treatment. Boiler water requires treatment to protect both the boiler and the distribution system. Professional help will occasionally be required to stive specific problems. Further assistance may be obtained from the United States Army Engineering and Housing Support Center USAEHSQ Fort Belvoừ Virginia 22060. The material in this chapter is designed to acquaint the operator with the reasons for treatment and the techniques available. There are four primary reasons for treatment of boiler water. a. Minimize Corrosion of Boiler and Distribution System. Corrosion of the steam distribution system is the result of carbon dioxide and oxygen released from the boiler water. The carbon dioxide condenses to form carbonic acid which combines with the oxygen to attack he distribution system piping. Iron and copper particles .e returned to the boiler as suspended solids which collect as boiler scale and sludge and promote corrosion in the boiler. Leaks in distribution system piping result in energy lost as steam or hot water. Additional raw water must also be treated to replace the water or steam lost adding to the water treatment cost and quantity erf impurities added to the system. Figure 4-1 illustrates oxygen pitting of a condensate pipe. b. Minimize Boiler Scale Deposits. Boiler scale deposits act as insulation which can result in overheating of the tubes and subsequent tube failures. Deposits also reduce heat transfer through the tubes causing higher boiler exit gas temperatures and lower boiler efficiency while promoting corrosion by allowing the concentration of impurities under the scale. Figure 4-2 illustrates a boiler tube which has failed due to scale. c. Improve Efficiency of Operation. As noted above control of boiler scale and system leakage due to corrosion helps to maintain a plants operational .