SCR烟气脱硝尿素热解炉前烟气加热器技术研究

在以尿素为还原剂的选择性催化还原(SCR)脱硝系统中,热解炉前电加热器耗电量大。为降低电耗,某电厂在640 MW机组脱硝改造中将电加热器系统改造为旁路做备用,增加高温烟气加热器,利用高温烟气对热一次风进行加热,所用高温烟气(约650℃、6 000 m~3/h(标准状态))从高温再热器后、低温再热器前的水平烟道引出。分析研究了这一技术路线,并对改造效果进行变负荷性能试验。数据分析结果表明,此项改造技术可行,且实施方便、运行良好,高温烟气加热器完全可取代电加热器,因而可降低机组厂用电率,节省电厂供电成本。

Research on Flue Gas Heater for Urea Pyrolysis of SCR Flue Gas De-NOx System

In the SCR(Selective Catalytic Reduction, SCR) denitrification system adopting urea as the reducing agent, the power consumption of the electric heater in front of the pyrolysis furnace is high. In order to reduce the power consumption, in the technical retrofit of the 640-MW unit in a power plant, the electric heater is modified as a bypass system, a high temperature flue gas heater is installed and the high temperature flue gas is used to heat the hot primary air. The high temperature flue gas, of which the temperature is about 650 ℃ and the flow is about 6 000 m3/h under standard state, is induced from the horizontal flue between the high temperature and the low temperature reheaters. The technical route is analyzed, and the retrofit effect is verified by variable load tests. The data analysis shows that the technical route is feasible and easy to implement, also the system runs well. Therefore, the high temperature flue gas heater can completely replace the electric heater reducing the house service rate and power supply costs.