Design And Application Of Flue Gas Denitrification Control System Based On DCS

In recent years, with the continues increasing of thermal power installations, thermalpower plants have discharged more nitric oxides(NOx). Nitric oxides, which would bringsever negative effects to our environment not treated properly. Therefore, it is of vitalimportance to control the discharging of NOxby thermal power plants. SelectiveCatalytic Reduction(SCR), because of the technology is mature, with a highdenitrification rate and almost having no secondary pollution, has become the mostpopular flue gas denitrification technology.According to the denitration system of600MW thermal plant in Zhangshan powerplant, through the analysis of the work principle and the craft of the SCR gasdenitrification and combined with the actual situation of the plant, this paper design thedenitration control system based on DCS. Complete the commissioning of the denitrationsystem and the situation of168h running of the system. Finally, according to problem ofthe start-up process of the denitration system, we find the solutions. The maincontribution and work are described as following:（1）Based on the analysis of the work principle and the craft of the SCR gasdenitrification, this paper design the denitration control system based on DCS, the DataAcquisition System(DAS), Modulating Control System (MCS), Sequence ControlSystem(SCS) and the main protection of interlock system.（2）Complete the monomer debugging, partial system debugging and a completeset of debugging of SCR denitration system, system performance test, ammoniadistribution test and the molar ratio deviation test. Briefly introduce the situation of168hrunning of the system.（3）There are some problems of the SCR denitration system in the start-up process,such as the export of NOxcontrol system has integral saturation, the temperaturemonitoring of catalyst, the control of denitrification efficiency and and so on. Throughthe analysis of the problem, we find the best solutions.During the whole set commissioning and its practical application, SCR DenoxSystem of Zhang Shan Power Plant in Shanxi Province passes the test of all kinds ofloads and operation conditions, whose main systems can operating in the normal, stableand continuous way. During the process of operation, DCS makes the operating creweasy to control different parameters, which makes sure the stable operation of its ownsystem. The whole process of operation tests and verifies the reliability and the stability of DCS.