Study On Low Temperature Waste Heat Utilization And Dust Pollution Control

Low-temperature corrosion caused by flue gas condensation can seriously affect the security of the waste heat utilization system.High temperature of exhaust flue gas is used to prevent the occurrence of condensation.The heat loss of exhaust smoke accounts for more than 70%of the total loss,which contains huge waste heat resources.Low temperature corrosion has become the main factor restricting the utilization of waste heat.The flue gas dew point is the key indicator of low temperature corrosion,which restricts the deep utilization of waste heat at the rear of the boiler.In this paper,the theoretical and experimental study of acid dew point is carried out and the existing formula of acid dew point is summarized.Aiming at the limit temperature of low temperature waste heat utilization,two sets of detection equipment for flue gas corrosion were designed,and field tests were carried out.Results compared with the calculated results show that there is big difference between the acid dew points obtained by different existing formula,and the limit of low temperature waste heat utilization is increased by about 10℃.In this paper,a 1000MW unit is taken as the research object.Dust emission and energy consumption are tested under three working conditions.The comparison of the dust removal efficiency of the unit at the same working condition between the coal-fired unit adding low temperature economizer and unit which donot.It is found that the use of low temperature economizer has effective control of dust emission,and the exportation of the electrostatic precipitator is reduced to about 21mg/m~3.The generating increment of the steam turbine is much higher than the auxiliary power consumption.The effect of the waste heat utilization is remarkable.Based on general conditions of low temperature boiler economizer in large power plant,for 6 kinds of H-type finned tubes of constant cross-sectional area,this paper analyzed the flow and temperature field using FLUENT software and field synergy principle.Results show that the flow and temperature field of 2mm×50mm H-type finned tube possessed high synergy and small flow resistance,the comprehensive heat transfer effect is better.