Jian Xing Ren

A Numerical Simulation of Diffusion Charging Effect on Collection Efficiency in Wire-Plate Electrostatic Precipitators

In this paper, a numerical simulation was carried out to analyze the effect of diffusion charging on collection efficiency of a wire-plate electrostatic precipitator (ESP). The gas flow field, the electric field, and the particle field with diffusion charging considered were included in the numerical model, which was implemented by using the commercial FLUENT software. Collection efficiency was calculated by using the Deutsch-Anderson equation, in which the parameters were provided from the numerical solutions. The simulated results indicate that the effect of diffusion charging on the wire-plate ESP particle collection increases with the decreasing particle diameter, as well as applied potential, particularly for PM10. Moreover, with the increasing applied potential, collection efficiency of PM10 is obviously improved, and the effect extent first increases and then decreases with particle size increasing, but also, the size range of particle, which is significantly affected by the diffusion charging, becomes smaller. As gas velocity becomes higher, the effect of diffusion charging on grade efficiency also becomes more obvious, and the affected range of particle size gets much larger, however, at the price of grade efficiency decreasing. Using collection efficiency as reference variable of judgment, instead of particle charge, may lead to a more accurate estimation of the aforementioned size range, which can provide a great help in the further analysis of fine particle collection.

PM2.5 removal performance of a wire-pipe ESP under multi-field coupling and applied magnetic field

In order to study PM2.5 removal performance under multi-field coupling and applied magnetic field, a mathematical model was proposed to analyze the interaction between fluid flow field, electro- magnetic field and particle dynamic field. The computational fluid dynamics method and FLUENT were employed to numerically simulate the PM2.5 removal performance in a Wire-pipe ESP. The effects of magnetic field on PM2.5 collection efficiency at different working voltages and gas velocities were discussed. The results indicate that the influence of applied magnetic field on PM2.5 collection in the wire-pipe ESP becomes more obvious with the increase of the particle diameter, and the increment of PM2.5 grade efficiency decreases with the increasing magnetic flux density in a certain range of particle diameters. Furthermore, the effect of magnetic field on PM2.5 collection increases with a decrease of working voltage or an increase of gas velocity, and PM2.5 collection efficiency declines at the same time. At a lower flue gas velocity, the impact of flue gas velocity on PM2.5 overall efficiency is more significant than that of applied magnetic field.

Technology to Control PCDD/Fs from MSW Incineration Processes

At present the dioxin problem caused by MSW(Municipal solid waste) incineration has become the point problem of the development of application. According to the formation mechanisms of dioxins in the process of MSW incineration prevention measure may divide into the combustion, the combustion before and burn the latter three broad headings prevention measure which produced the PCDD/Fs after burning area mainly include in the haze, the flying ash the PCDD/Fs removing and prevents some measures which PCDD/Fs produces. Finally this paper proposed several measures in control and purification dioxins technology.

Experimental Study of the Effect of Fly Ash Particle Size on its Mercury Adsorption Capability in the Flue Gas

In this paper, fly ash samples were collected from a coal-fired power in Shanghai. A series of experiments, including unburned carbon testing, mercury content measurement, SEM analysis, specific surface area, average pore size and pore volume test, were conducted, and the adsorption ability of the fly ash on the flue gas mercury was also experimentally studied. It has shown that fly ash with particle size bigger than 100µm is with the highest adsorption efficiency, 67.83%, and that fly ash with particle size smaller than 25µm is with the smallest adsorption efficiency, 13.67%. The relative mechanism was analyzed.

Experimental Study on the Relationship between Mercury Enrichment Coal and the Depth of Coalseam

The mercury concentration in the coals from Datong and Xiaoyi, Shanxi has been measured to study the relationship between mercury enrichment in coal and coalseam depth. Ten samples were researched, of which 7 coal and rock samples from the main coalseam and the places around it were collected at a miner in Datong city, and 3 coal samples from three coalseams at a miner in Xiaoyi city. The mercury concentration in the coal and rock samples was measured with US EPA Method7471, which is a standard method recommended by the US EPA. The results show that the mercury enrichment in coal is higher than that in rock in the same conditions, and the mercury concentration in the longer-buried coal is higher than that of the shorter-buried. However, the mercury concentration in coal with depth has no definite linear correlation, varying in different coal fields.

Study on the Gas-Liquid Two-Phase Flow Two-Phase Flow Characteristics of Carbon Dioxide Removal by Membrane Method

In this paper, membrane absorption method was introduced. Analyzed and studied flue gases passing in the shell side (hollow fiber membrane) and in the pipe side (membrane lumen) respectively. Total mass transfer coefficient and de CO2 efficiency were calculated. For flue gases passing in the pipe side, total mass transfer coefficient was 1.1191×10-4m/s and de CO2 efficiency was 73.8%; while for flue gases passing in the shell side, total mass transfer coefficient was 3.4701×10-4m/s and de CO2 efficiency was 98.0%. The results showed that the flow of flue gas flowing in the lumen is better than the flow of flue gas flowing out of the hollow fiber membrane from the point of views of removal rate and mass transfer. To build de CO2 experimental devices, flow of flue gas flowing in the pipe side was proposed.

Effect of Process Parameters on Solid Fuel Briquette of Rice and Soybean Straw

The compressive experimental produce is assigned to measure the compressive force, moving compressive length and their time consumption for the purpose of obtaining the quality and economical solid fuel briquette of rice and soybean straw. The two compressive processes are proposed in the analysis of the first compressive process. The results show that for the rice straw, the second compressive process is favorable for fabricating solid fuel briquette. While the hard soybean stems are intend to become the soft stems due to the presentation of broken stems under the high compresses in the first compressive process. The experiment reveals that the soft and hard stems of biomass feedstock shows the different properties which should be paid vital attention when design the pelletisers.

Economic Analysis of Water Source Heat Pump Using Thermal Power Plant Circulating Water Waste Heat

Using water-source heat pump for recovering waste heat of thermal power plant circulating water, mining of low grade heat energy. It can improve the power efficiency of comprehensive energy, but also can reduce the evaporation cooling water, the heat and moisture discharge to the environment. It has the economic, social and environmental benefits are very remarkable. Through the analysis of 600MW thermal power unit circulating water waste heat and calculation of water source heat pump heating, the feasibility of the water source heat pump technology in the recovery of power plant circulating water waste heat can be obtained.

Influence of Applied Magnetic Field on a Wire-Plate Electrostatic Precipitators Under Multi-Field Coupling

The aim of this work is to find an effective method to improve the collection efficiency of electrostatic precipitators (ESPs). A mathematic model of an ESP subjected to the external magnetic field was proposed. The model considered the coupled effects between the gas flow field, particle dynamic field and electromagnetic field. Particles following a Rosin-Rammler distribution were simulated under various conditions and the influence of the magnetic field density on the capture of fine particles was investigated. The collection efficiency and the escaped particle size distribution under different applied magnetic field intensities were discussed. Particle trajectories inside the ESP under aerodynamic and electromagnetic forces were also analyzed. Numerical results indicate that the collection efficiency increases with the increase of applied magnetic field. It was also found that a stronger applied magnetic field results in a larger particle deflection towards the dust collection plates. Furthermore, the average diameter of escaping particles decreases and the dispersion of dust particles with different sizes increases with the increasingly applied magnetic field. Finally, the average diameter decreases almost linearly with the magnetic field until it drops to a certain value. The model proposed in this work is able to obtain important information on the particle collection phenomena inside an industrial ESP under the applied magnetic field.

Analysis of the Relationship between Electrostatic Dust Removal Efficiency and its Factors in Coal-Fired Power Plant

With the national environmental standards becoming more and more strict, electrostatic precipitators is facing the new challenges, promoting the efficiency further and reducing emissions are essential to achieve the environmental standards. This paper analyzed the influential factors of the dust removal efficiency of electrostatic precipitators in coal-fired units, and discussed the relationship between dust removal efficiency and its factors, which lay the foundation for improving the dust removal efficiency.