| Particulate matter and heavy metals from burning coal can cause serious pollution.At present,the commonly used dust removal equipment in coal-fired power plants has a "penetration window",in which the fine particles cannot be effectively collected,and the fine particles are enriched with a large number of heavy metal elements,posing a threat to the ecological environment and human health.Fine particulate matter and its heavy metals have become hot and difficult points in the field of pollution control.A new approach is to install a turbulent coalescing device in the ESP front end to increase control of fine particulate matter.This paper mainly studies the control of fine particulate matter in the turbulent coalding section and the distribution of heavy metals in granular state by installing coalmerges in actual power plants and building coalmerges platforms in laboratories.At the same time,Fluent software is used to simulate the flow field and coalmerges in the coalmerges to optimize the experimental system.Firstly,a coalesced device was installed in front of the generator ESP in hubei xisaishan power generation co.,LTD.The experimental results show that the installation of the coalescer has a certain effect on the emission reduction of particulate matter,especially fine particulate matter,and the gaseous heavy metals are transformed into particulate matter after turbulence disturbance.By SEM after testing found that fine particles in the process of reunion will adhere to in the big particle surface,can be observed on the surface of the spherical aggregates,on the other hand dry laser particle size test showed that gather and after 1 to 10 microns diameter particles volume fraction increased,confirmed the fine particles adhesion in the larger particles surface size larger phenomenon.Due to the great difficulty in the field test of coalescing experiment,a coalescing experiment platform with freely adjustable parameters was developed to study the influence of different parameters on coalescing effect,and the coalescing system was optimized based on the experimental and simulation results.The experimental platform mainly consists of the following parts: wind tunnel,air preheater,aerosol generator,coalizer and particle dilution system.The adjustable power of the air preheater is 0-30 kw,and the flue gas temperature can be changed within the range of 20-150℃ by changing the working power.The working frequency of the variable frequency fan is up to 50 Hz,which can realize the change of fluegas flow rate within 0-30m/s.The change of flue gas flow rate can be realized by changing the working frequency of the converter.The aerosol generator is equipped with control software to adjust the transmission speed of the generator conveyor belt to realize the change of flue gas concentration within the range of 0-20g/m3.The convertor has a built-in spoiler blade.Different types of blades are connected to the clapper through screw holes and can be disassembled to realize the change of blade types,which are mainly composed of curved,straight and z-type blades.The Angle of blade facing the flow is realized by turning the external knob,and the Angle is freely adjusted from 0° to 90°.A groove with a spacing of50 mm is arranged on the surface of the partition,and the blade spacing can be changed by placing the blades in different grooves.At the same time,Fluent numerical simulation results show that the higher the flow rate of flue gas is,the more favorable it is for the formation of reflux vortices.Considering the flow field and convergence rate,the best convergence effect is found when the flow rate of flue gas is 12m/s.The results of this paper show that turbulent polymerization has a good effect on the reduction of fine particulate matter,and the process of turbulent polymerization can promote the transformation of gaseous heavy metals into particulate matter,providing experimental guidance for the reduction of particulate matter and heavy metals. |
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