Study On Flue Gas Denitration Modification Technology Of 2×300MW Unites In Linhe Thermal Electric Power Plant

The problem of NO_x emissions of pollutants in coal-fired power plants has become more and more attention in China.Many domestic power plants have installed the denitration equipment to meet the new discharge standards.At present,the boiler low nitrogen combustion technology and the flue gas SCR flue gas denitrification equipment are the main technologies for controlling nitrogen oxide emission in coal-fired power plants.In this paper,the flue gas denitration project of Linghe thermal power plant as the study objective was studied.The paper first introduces and analyzes the original structure of boiler body and combustion system.In order to accurately grasp the NO_x emission situation of the former crew,the tests under different loads were carried out.Combined with the field operation data,the boiler combustion efficiency,the NO_x emission concentration and the inlet flue gas temperature of the economizer has been fully and accurately grasped.The tests results show that the basic NO_x concentration of the denitrate modification project can be designed by 600 900mg/Nm³,the inlet mean flue gas temperature of the economizer is about 335³76?.The temperature range is within the normal operating temperature range of the SCR catalyst.These data are really the important foundation for the design and implementation of the next step of denitrate modification project.Secondly,according to the technical comparison,the denitrate modification project technology plan of the two parts of the 2×300MW units of Linhe thermal power plant is determined.Low NO_x burners stage combustion in the furnace and SCR flue gas denitrate equipment in flue gas pass are combined together.A new type of high concentration burner is used to replace the current one with a high concentration ratio and add the high over high air that is used the stage combustion to control the NO_x emission in Low NO_x combustion modification.The SCR reactor is placed between the economizer and air heater.Each boiler sets two SCR reactors.In order to meet the resistance requirement,the modification scheme of the combination of the draught fan and desulfurization boost fan is adopted.Finally,the test and field operation data were analyzed after the modification.The test results of the low NO_x burner showed that the boiler combustion efficiency is not lower than before the modification,NO_x emission concentration is below 400mg/Nm3,and the CO content is not greater than 100?L/L.The aim of the modification was realized.By analyzing the test results and the operating performance of the SCR flue gas denitration device,all the technique data meet the design requirements.The denitration efficiency of the SCR system can achieve more than 80%.The ammonia escape rate of the reactor A and B reached the design requirement of less than 3.0×10-6.SO₂ / SO₃ conversion rate is below 1.0 design requirement.The actual ammonia consumption is less than the design value of the 150kg/h.The pressure drop of the SCR system is less than 400 Pa and temperature drop is less than 2 ?.Through the modification of the nitrogen removal technology of the two units,the level of NO_x emission concentration is less than 100 mg/Nm³ which meet environmental emission requirements.The results can provide important scientific reference for the denitration modification design and optimization of the same kind coal-fird units.