To ensure stable operation of electrostatic pr翻译文献.doc

To ensure stable operation of electrostatic precipitator efficiency measuresESP is a highly efficient dust collector, has been more and more used by coal-fired power plants. Electrostatic precipitator in order to maintain long-term, high-performance and stable operation, it should be affecting the efficiency of electrostatic precipitator factors analysis, and to the strengthening of electrostatic precipitator operation, maintenance and overhaul management.1 Affect the efficiency of electrostatic precipitator dust factor1.1 High-low-voltage power supply control device design and operation of the poorReasonable corona ESP power is to ensure safe, stable operation of one of the important factors. ESP 380V DC high voltage from high-voltage alternating current flowing through thyristor rectifier equipment supply, electric dust collector of high-voltage power supply impedance is a load change. Impedance when the electric field increased ER-hour requirements of equipment to automatically step-up; lower impedance when the electric field and current become larger, the requirements of equipment to automatically step-down in order to maintain the current settings. Internal transformer rectifier voltage and current sampling resistor, the introduction of negative feedback signals, processed by the microcomputer intelligent control thyristor phase-shift of the conduction angle, the output voltage to change the load to the purpose of output, so that the most effective electric field of corona power. However, some power and control equipment, factory production control of the controller of the device characteristics and control methods are not perfect protection, etc., coupled with the power plant operation and maintenance personnel of equipment There is a certain understanding of the principles of the blind spot, resulting in power supply poor operation of control devices.1.2 vibration cleaning device operating mode unreasonableAt present, thermal power plants in addition to the use of electricity, and all is vibration cleaning methods. In the vibration intensity and uniformity requirements are met, the vibration system (cycle time, the way) is reasonable for the efficiency of electrostatic precipitator dust impact. Vibration cycle, the impact on the collection efficiency is to be able to make when cleaning off the dust from falling into the ash bucket directly block. Vibration cycle is too long, fouling plate thickness, will reduce the dust in the very board charged the conductive properties, reducing collection efficiency; vibration cycle is too short, dust will be dispersed into falling, have given rise to the second dust , that is deposited on the electrostatic precipitator dust collecting on the pole again with a dust collector currents, in particular the electric field at the end of the second polar dust would greatly reduce the efficiency of electrostatic precipitator.Dust caused by the second there are many factors, such as high resistivity dust, resulting in anti-corona electric field collecting the uneven distribution of the flue gas flow rate or flow rate caused by high turbulence and swirl. Therefore, the requirements of the electric field of flue gas flow rate of not more than 3m / s, the general operation of the electric field in the flue gas flow rate 1.5m / s or so, and the possible distribution of flue gas flow, and the vibration frequency of cleaning off is caused by dust Secondary dust factor. Follow certain procedures, using appropriate test methods, establish the right vibration system, at the same time strengthen the gray ash bucket equipment maintenance to prevent gray ash blocked out the Big Dipper, can prevent the occurrence of secondary dust.1.3 boiler operating parameters deviate from normalUnder the normal load in the boiler flue gas flow, exhaust gas temperature, flue gas dust concentration and other parameters with the design parameters of electrostatic precipitator or less the same as all the normal operation of electrostatic precipitator. If the boiler flue gas flow increases, smoke temperature, flue gas dust concentration increased, the electrostatic precipitator operating conditions will deteriorate, so that lower collection efficiency. When the boiler low-load running time, in order to stabilize combustion, must be input for combustion of heavy oil or diesel, resulting in flue gas temperature and increase in the viscous material. These viscous materials hypertrophy caused by cathode-ray anode plate deposition, resulting in decreased efficiency of the electric field of the dust. If vapor leaks in the boiler, flue gas will increase the humidity, although in a very short time because of smoke and quenched and tempered by lower resistance than the ash, dust removal efficiency will be increased, but a little longer, will seriously fouling ESP, In particular, when the disclosure of large, plate or scale, will reduce the life of precipitator.1.4 changes in coalIf coal burning boiler changes in the design of its calorific value than coal with low ash coal than the design of high, it will increase its coal, flour mills, dust, ash equipment wear and shorten the maintenance cycle of the equipment. The use of low calorific value coal, the actual coal-fired boilers will increase so that the volume of flue gas containing ash increased. This will make ESP more than dealing with the design of flue gas dust concentration values, collection efficiency will be seriously affected. In order to eliminate coal from the impact of changes in collection efficiency of electrostatic precipitator, dust removal equipment in the system under normal circumstances, each electrostatic precipitator should be carried out at least one of the characteristics of typical coal tests to determine the coal, electricity , vibration efficiency electrostatic precipitator for the combined effect of the ESP to find the best operating mode.2 strengthen the electrostatic precipitator maintenance and repair work(1) State Power Environmental Protection produced by DJ series of computer-controlled high-low-voltage power supply devices, and its use of advanced high-pressure control part of the 8098 single-chip and peripheral chips, control, protection functions, simple structure, easy-to-use features, and for thermal power plant boiler combustion emission of dust (fly ash) than the changes in resistance provides a wide range of power supply to run a variety of different ways to meet the requirements of working conditions. This power supply equipment for the original transformation, the central plane can be achieved with long-range and turbidity dust detector constitute the feedback signal of the closed-loop control electrostatic precipitator, to the effect of energy-efficient operation. Their protection and alarm functions involved in the importation of over-current, output open-circuit, output short circuit, undervoltage protection, partial excitation, SCR risk of open and critical temperature, the thermal power plant is almost covered by the operation of electrostatic precipitator for all fault types.(2) efforts to improve the status of the operation of electrostatic precipitator, strictly enforce the electrostatic precipitator operation and maintenance guidelines， the existence of the operation of the equipment failures and shortcomings should be in time, establish a comprehensive, reasonable maintenance and project cycle.(3) maintenance area. Overhaul at the electrostatic precipitator in overcast, anode spacing adjustments, and record the measurement results before and after adjustment. To overcast, anode device vibration equipment (mainly electrical vibration, reducing the browser machine, shaft, bearings, torsion arm hammer, insulation connecting rod, etc.) to inspect the wear and handling; of ash systems, insulation, heating systems, Doo-gray level meter, devices such as locking gas inspection and debugging.(4) electrical connection. Enforcing overhaul of preventive tests electrical equipment order in the electrostatic precipitator transformer rectifier sections of high pressure and low pressure reactor, insulating support and connected components, high voltage direct current cables and other equipment of the pilot project and the express provision of the cycle, to trigger power supply device performance testing, on a variety of protection throughout the trial, the high-low voltage electrical circuit and switch instruments seized the school, and hanging rectifier to change the core inspection.(5) ESP overall debugging after overhaul. After the overhaul of the rectifier transformers, electric field to no-load step-up test, and run-time conditions to the rated characteristics of the U-I testing; of imports and exports of flue gas temperature and pressure testing instructions; of Turbidimeter, lighting equipment for testing. If the conditional words, it should also be on the ESP collection efficiency before and after overhaul comparison test, to test the effectiveness of repair work.保证电除尘器高效稳定运行的措施电除尘器是一种高效的除尘器，已被越来越多的火力发电厂所采用。为了保持电除尘器长期、高效、稳定地运行，应该对影响电除尘器效率的因素进行分析，并加强对电除尘器运行、维护和检修的管理。1影响电除尘器除尘效率的因素1.1高低压供电控制装置设计运行不佳合理的电除尘器电晕功率是保证电除尘器安全、稳定运行的重要因素之一。电除尘器直流高压由380V交流电流经可控硅高压整流设备供给，除尘器电场阻抗对高压供电装置来说是一个变化的负载。当电场阻抗升高、电流变小时，要求设备能自动升压；而当电场阻抗降低、电流变大时，要求设备能自动降压以保持设定的电流。整流变压器内部的电压、电流取样电阻，引进负反馈信号，经微机智能处理后移相控制可控硅的导通角，改变负载输出电压，达到稳定输出的目的，使电场获得最有效的电晕功率。然而有些电源及控制设备制造厂生产的控制器对设备控制特性和控制方式、保护功能等还不完善，再加上电厂运行和检修人员对设备原理的理解存在一定的盲区，从而造成供电控制装置运行不佳。1.2振打清灰装置的运行方式不合理目前，火电厂使用的电除器，无一不是采用振打方式清灰。在振打力度和均匀性都满足要求的情况下，振打制度(周期、时间、方式)是否合理对电除尘器除尘效率影响极大。振打周期对除尘效率的影响在于清灰时能否使脱落的尘块直接落入灰斗。振打周期过长、极板积灰过厚，将降低带电粉尘在极板上的导电性能，降低除尘效率；振打周期过短，粉尘会分散成碎粉落下，引起较大的二次扬尘，即沉积在电除尘器收尘极上的粉尘再次被气流带出除尘器，尤其是末极电场的二次扬尘会大大降低电除尘器的效率。导致二次扬尘的因素有许多，如粉尘的比电阻过高，产生反电晕收尘电场的烟气流速分布不均或流速过高而产生的紊流和涡流。因此，要求电场的烟气流速不超过3m/s，一般电场中运行的烟气流速都在1.5m/s左右，且尽可能使烟气流分布均匀，而振打清灰过频，是造成除尘器二次扬尘最主要的因素。遵循一定的程序，采用恰当的试验方法，建立正确的振打制度，同时加强对灰斗排灰设备的维护，防止灰斗出灰口堵塞，都能防止二次扬尘的发生。1.3锅炉的运行参数偏离正常值在正常负荷下锅炉的烟气流量、排烟温度、烟气含尘浓度等参数值与电除尘器设计的参数相差不大，电除尘器都能正常运行。若锅炉烟气流量增大、排烟温度升高、烟气含尘浓度增加，电除尘器的运行工况就会恶化，使除尘效率降低。当锅炉长时间低负荷运行时，为稳定燃烧，必须投入重油或柴油助燃，造成烟气温度和烟气中的粘稠物增加。这些粘稠物造成阴极线肥大，阳极板积灰，导致电场的除尘效率下降。如果锅炉内水汽泄露，将增加烟气湿度，虽然在极短时间内因烟气被调质而降低了煤灰比电阻，除尘效率会升高，但时间稍长，电除尘器将严重积灰，尤其在泄露量大时，极板甚至结垢，会降低除尘器的使用寿命。1.4 煤种的变化如果锅炉燃烧煤种发生了变化，其热值较设计煤种低，灰分较设计煤种高，则会加大对输煤、制粉、除尘、输灰设备的磨损，缩短设备的检修周期。使用低热值燃煤，会使锅炉实际燃煤量增加，使烟气的含灰量增大。这样会使电除尘器处理烟气含尘浓度超过设计值，除尘效率将受到严重影响。为了消除因煤种发生变化而影响电除尘器的除尘效率，在除尘设备系统运行正常的情况下，每套电除尘器至少应进行一次针对典型煤种的特性试验，以确定煤种、供电、振打对电除尘器效率的综合影响，找出电除尘器的最佳运行方式。2 加强对电除尘器的维护和检修工作(1)国电环保所生产的DJ系列微机自控高低压供电装置，它的高压控制部分采用先进的8098单片机和外围芯片，具有控制、保护功能完善、结构简单、使用方便的特点，并针对火电厂锅炉燃烧排放粉尘(飞灰)比电阻的变化提供多种供电运行方式满足各种不同工况条件的要求。采用这种供电装置对原有的设备进行改造，可实现中央机远程并借助粉尘浊度检测仪的反馈信号构成电除尘器的闭环控制，达到高效节能运行的效果。其保护和报警功能涉及输入过流、输出开路、输出短路、欠压保护、偏励磁、可控硅开路和临界危险油温，几乎涵盖了火电厂电除尘器运行中的所有故障类型。(2)努力改善电除尘器的运行现状，严格执行电除尘器运行维护导则，对于设备运行中存在的故障和缺陷应及时处理，制订完善、合理的检修周期和项目。(3)机务方面。大修时对电除尘器内阴、阳极间距进行调整，并记录调整前后的测量结果。对阴、阳极振打装置的设备(主要有振打电机、减器机、转轴、轴承、挠臂锤、绝缘连杆等)磨损情况进行检查并处理；对出灰系统、保温、加热系统、灰斗料位计、锁气器等装置进行检查和调试。(4)电气方面。大修时严格执行电力设备预防性试验规程中电除尘器章节对高压硅整流变压器、低压电抗器、绝缘支撑及连接元件、高压直流电缆等设备的试验项目和周期所作的明文规定，要对供电装置的触发装置进行性能测试，对各种保护进行整定试验，对电气高低压回路与仪表开关进行校检，并对整流变进行吊芯检查。(5)电除尘器大修后的整体调试。大修结束后，对整流变压器、电场进行空载升压试验，并在运行时进行额定工况下的U-I特性测试；对进、出口烟气温度与压力指示进行测试；对浊度仪、照明设备进行测试。如果有条件的话，还应该对电除尘器大修前后的除尘效率进行对比试验，以检验大修工作的效果。