Slagging Diagnosis Of Boiler Based On Impact Signal Of Fallen Slag

Limited by China's energy structure,coal-fired thermal power generation will continue to be the main component of China's electric power in the long future,bearing the basic load of the power grid.Slagging on heating surface has always been an unavoidable problem in the operation of coal-fired boilers.Slagging of boilers increases heat-transfer resistance,flue gas loss,reduces boiler efficiency,and may cause high temperature corrosion,water wall bursting,or even result in safety accidents if the slagging problem is not solved in time.Therefore,it is very important to carry out the research of boiler slagging diagnosis and to find and solve the slagging problem in time both for the economy and safety of the unit operation.On the basis of analyzing the existing slagging monitoring methods,a new slagging diagnosis method based on impact signal of fallen slag is proposed in this paper.This method needs fewer measuring points,lower equipment investment,and will not cause damage to the water wall or reduce its strength.The main contents of this paper are as follows:According to the actual situation of the boiler,a flat impact test-bed is designed and built.The feasibility of the slagging diagnosis method and the rationality of the simulation experiment are demonstrated theoretically from three aspects: the influence of the inclination of the ash hopper,the influence of the fluid in the water wall pipe and the selection of slag simulator.The parameters of slag quality,surface hardness and porosity fluctuate greatly,and therefore the frequency fluctuation of vibration signal caused by collision makes the propagation velocity unpredictable.To solve this problem,a grid location method based on time difference ratio is proposed,and the arrival time of signal is determined by energy envelope method.The simulation experiment proves that the method has reliable location accuracy,and the factors affecting the accuracy are analyzed.Through noise simulation experiments,it is proved that this method has certain anti-interference ability,and has high application value.Based on Hertz impact theory,a method for estimating the drop height of slag is proposed,which takes the short-term average amplitude of impact signal as the eigenvalue.The height estimation curve models of ceramic ball and autoclaved aerated concrete blocks are established.The simulation results verify the accuracy and reliability of the curve model.