Efficiency Increase In ESP Based On Heat Transfer Collection Electrode

According to the growing problem of air pollution in China especially the severe weather problem of haze, the soot emission of coal-fired power plant attracts extensive attention all across the nation. The soot emission concentration in the New Fossil-fuel Power Plant Atmospheric Pollutant Emission Standard in 2011 dropped from 50mg/Nm3 to 30mg/Nm3, and in the key area to 20mg/Nm3. It was supposed to the strictest standard in the world. But the traditional dust removal system in coal-fired power plant cannot adapt to the new standard. Especially the electrostatic precipitator (ESP), as the main PM removal equipment, also has lots of problems to solve. So the efficiency increase of ESP is our research emphasis in future. And the technological innovation of environmental protection equipment not only roots from the emission reduction, but also from the demand and encouragement to energy conservation from the nation. So both the strict environmental protection standard and the pressing demand of energy conservation impel the development of upgrading and rebuilding of ESP in coal-fired power plant.On that account before, the efficiency increase technical route of ESP based on recombination of the heat transfer and dedust increase efficiency collection electrode was proposed and designed. Along this path of thinking, the test bed was designed and rebuild from the design thought of Cottrell ESP. The test was about dedust increase efficiency and heat transfer efficiency by the means of replacing traditional Z-type collection electrode with recombination of the heat transfer and dedust increase efficiency collection electrode.The dedust increase efficiency was tested by two means, which are PM dedust efficiency and particle size distribution efficiency. Based on those two means, the conclusions are that the dedust increase efficiency of new-type collection electrode is better than the traditional Z-type collection electrode. Because the new-type collection electrode increased the velocity of PM’s approach, enlarged the specific surface area of the collection and decreased the practical flue gas quantity. And also the saturation dust thickness was found that the value was 2.1mm. This engineering application diameter could guide the practical application in engineering.According to the recombination of the heat transfer and dedust increase efficiency collection electrode, the influence parameters which are velocity of gas flue, velocity of air, the duration stay of air, the temperature of gas flue was tested to verify the influence of these parameters to heat transfer efficiency. And heat exchange amount was imported to indicate the heat transfer efficiency. The conclusion was that the velocity of gas flue has direct ratio relations with heat exchange amount; the velocity of air has logarithm ratio relations with heat exchange amount; to settled size of collection electrode, there is a best velocity of air which was 10m/s and the duration stay of air which was 1.5s; at last the temperature of gas flue has direct ratio relations with heat exchange amount.An assumption was made at one ESP in a certain 300MW coal-fired power plant to use this efficiency increase technical route of ESP based on recombination of the heat transfer and dedust increase efficiency collection electrode. The technological economy of this route was analysis and calculated. After replacing traditional Z-type collection electrode with recombination of the heat transfer and dedust increase efficiency collection electrode, the soot emission concentration could reach a higher level which was 32.5mg/Nm3, the total PM emission reductions in one year could be 173.8t, and these reductions could save expense on pollutant emission which could be 48 thousand Yuan. And also the replacement could make the plant to reach the new emission policy, the subsidy of standard could be 3 million Yuan. After the replacement, the waste-heat utilization could increase the efficiency of the boiler. The increase of the efficiency could directly reduce rated coal consumption which could be 1.0g/kWh. And after conversion of the coal calculation, the coal fired cost which was 645 thousand Yuan one year could be saved. And the influence to air blower power of the plant also should be calculated, the increase cost of this influence could be 888 thousand Yuan per year. Due to the new policy, the award of emission reductions could be 360 thousand Yuan. And after the calculation of primary expenses such as materials expenses, installation expenses, the total investment expenses was 2.152 million Yuan, the capital payoff needs 0.68 year.