增设零号高压加热器控制SCR脱硝烟温对机组经济性影响的计算研究

摘要

It is able to improve entrance flue gas temperature of selective catalytic reduction (SCR)denitration reactor under low and medium load by adding No.0 high pressure heater. In order to determine its influencing law on unit economy,this paper takes one domestic 600 MW unit for a research object and firstly confirms running parameters of the No.0 high pres-sure heater respectively under 50%,60% and 70% rated load,and then calculates thermal performance and cost changes under different working conditions. Results indicate that after adding No.0 high pressure heater,temperature of feeding water improves exhaust gas temperature which may increase SCR denitration efficiency and reduce cost,but increase fire coal cost for unit operation at the same time. In addition,compared with wide open condition of the extraction valve,economy of the mode of steam extraction and energy conservation is reduced. Thus,it is needed for coupling low temperature economizer to reduce exhaust gas temperature so as to eliminate negative influence of additional No.0 high pressure heater on unit economy.%增设零号高压加热器可提高燃煤锅炉在中低负荷时选择性催化还原(selective catalytic reduction,SCR)脱硝反应器入口烟温,为确定其对机组经济性的影响规律,以国内某电厂600 MW机组为研究对象,首先确定了50%、60%和70%额定负荷下零号高压加热器的运行参数,进而对增设零号高压加热器后各工况进行了热力性能和成本变化的计算。结果表明：增设零号高压加热器后,给水的温升提高了排烟温度,这会提高 SCR 脱硝效率,降低了脱硝成本,但同时会增加机组运行的燃煤成本；且较抽汽阀门全开方式,抽汽节流方式的经济性是降低的。因此,若采用零号高压加热器技术,需要耦合使用低温省煤器来降低排烟温度,以消除零号高压加热器的增设对机组经济性的不利影响。