After low nitrogen burner, denitration system and the corresponding auxiliary after modification, in the actual operation of NOx emissions can meet the national requirements of environmental protection, for the normal operation of the unit in the future created prerequisites, at the same time also bring some negative effects on unit.
一、机组最小手艺出力降低，调峰能力差 1. The minimum technical output of the unit is reduced and its peak regulating capacity is poor
大部门电厂的脱硝均采用SCR脱硝回响器，催化剂的设计温度为300℃～420℃。在机组投入脱硝系统运行后，除同步投产脱硝系统的机组外，因为早期汽锅设计未考虑脱硝系统的运行温度，多数机组革新后涌现了汽锅低负荷运行时，省煤器出口烟温无法知足脱硝系统正常运行温度的现象，因而汽锅最小手艺出力较革新前均有分歧水平的升高，机组的调峰能力下降。针对上述状况，拔取山西省具有代表性的九个电厂进行了调研，综合九个电厂的最小手艺出力情形，革新后机组的最小手艺出力在50%-77%之间。经加权平均，汽锅最小手艺出力平均为59%，较革新前40%的最低稳燃负荷提高了19%;仅就革新机组来较量汽锅最小手艺出力平均为62%，汽锅最小手艺出力较革新前提高了22%。此中，原设计低氮燃烧器和脱硝系统的机组结果最佳，低氮加脱硝同时革新的机组结果最差。 Most of the power plant of denitration adopt SCR denitration reactor, catalyst design temperature is 300 ℃ ~ 420 ℃. After denitration system run operation unit, in addition to the synchronous production unit of denitration system, due to early boiler design did not consider the operating temperature of the denitration system, most of the unit after transforming the low load running, the boiler economizer outlet smoke temperature can meet the phenomenon of denitration system normal operation temperature, and minimum technology before the transform of output has the varying degree to rise, the peakload ability decline. According to the above situation, choose the typical nine power plant in Shanxi Province has carried on the investigation and research, comprehensive nine power plant, the minimum technical output, after transforming unit, the minimum technical output between 50% and 77%. According to weighted average, the minimum technical output of boiler is 59%, which is 19% higher than the minimum stable combustion load of 40% before reforming. The average minimum technical output of the boiler was 62% when the unit was modified, and the minimum technical output of the boiler was 22% higher than before the reform. Among them, the original low-nitrogen combustion and denitrification system has the best effect, while the low-nitrogen and denitrification system has the worst effect.
二、AGC调节特征能差 2. Poor regulatory performance of AGC
机组在经由低氮燃烧器革新后，炉内的燃烧体式发生了显明改变，在使用原有协调体式的情形下，机组在投入AGC掌握时，主汽压力误差大、汽包水位波动;负荷调节速度较快时，因为脱硝喷氨反响存在滞后，轻易造成NOx排放指标在短时间内超标，严重影响负荷调节速度;同步进行引风机革新的机组，革新后未进行引风机调节特征试验，在低负荷时，在原有掌握体式下，炉膛压力波动大。 Unit after low nitrogen burner alteration, furnace combustion mode has changed significantly, in the case of using the original coordinate methods, unit in AGC control, big deviation main steam pressure, steam drum water level fluctuation; When the load adjustment rate is relatively fast, it is easy to exceed the standard of NOx emission in a short period of time due to the lag of denitrification ammonia injection reaction, which seriously affects the load adjustment rate. The unit that carries out the synchronous fan modification has not carried out the fan adjustment characteristic test after the modification. When the load is low, the pressure in the furnace fluctuates greatly under the original control mode.
Liquid ammonia, also known as anhydrous ammonia, is a colorless liquid, volatile, corrosive, irritating smell. The liquid ammonia volatilizes into ammonia gas, belongs to inflammable and explosive gas, which can cause poisoning after leakage, irritate eyes and mucous membrane, and is in danger of burns. There are safety hazards such as leakage, electrostatic fire, explosion and poisoning in transportation, loading, unloading, storage and maintenance of liquid ammonia. Using liquid ammonia as a reducing agent of power plant, potential safety hazard, especially near the urban areas of power plant, using liquid ammonia denitration, the transportation, storage, operation risk bigger, greatly increases the risk of unit operation.
2. Denitrification and transformation, high operating cost
Denitration modification increases the resistance of the original specific systems, denitration by-products have blockage and corrosion of air preheater, dust collector, induced draft fan and other equipment, to form a complete set of air preheater and induced draft fan renovation, a large range transform, high cost.