Precipitator Performance Improvement and Energy Savings based on IGBT Inverter Technology
Energy efficiency and energy saving become more important for many technical applications due to the higher cost of energy and environmental impact (e.g. CO2 emissions). Dust emissions need to be maintained below the emissions limits regardless of the operation mode or fuel type of the process.Basically, precipitator performance improvements can be achieved by applying higher electrical power to a precipitator. The limitation of a conventional SCR based high voltage power supply is the 50/60 Hz voltage ripple, which leads to flashovers during the peak voltage, while the average voltage is comparably low. High frequency IGBT inverter technology can deliver a DC voltage with a higher average value resulting in significantly higher power. Additionally, the current can be interrupted at any time for faster reaction to flashovers. High space charge density is avoided and therefore shorter wait time for deionisation is required resulting in higher average power. In case of high resistivity dust short superimposed pulses can be applied for increased charge density generation at the spray electrodes.Existing plants can be upgraded easily by just replacing the control cubicle, while the TR set can be kept in use in many installations. For optimum performance the TR set can be replaced by a high frequency (500 Hz/10 kHz) type. An advantage of this concept particularly can be found in existing plants, because the cable installation between the cubicle and TR set can be still up to 120 m.Grid current waveforms of IGBT inverters are different from SCRs. The reactive power demand is much lower due to the diode bridge at the input stage and the voltage link capacitor. The load current is symmetrical for the three phases. The harmonics of the grid current are typical for a standard diode rectifier. This is very common due to the fact that IGBT inverters are used for electrical drives frequently. The low demand of reactive power limits the apparent power to a value very close to the active power.Therefore supply transformers which are rated for the apparent power demand of the connected load can be reused, even if higher electrical power for the precipitator is required. For future requests the input rectifier can be equipped with an IGBT based power factor control to limit the harmonic distortion.Active Power savings (real savings) can be achieved by a computer based energy management system which calculates the required power for each zone of the precipitator. Due to the high dust load the inlet fields of a precipitator generally require more power than the middle fields or outlet fields. Practical tests have shown that the total power consumption of a precipitator can be decreased significantly, depending on the operation mode and the process conditions 0. Lowering the power of a precipitator results in a higher sensitivity to any process changes, particularly during collection electrode rapping when dust from the plates is being released. To avoid dust emission peaks the high voltage and current control has to be synchronized with the rapping interval of the entire field. Increasing the current during rapping has been proven to keep the emissions low, even during rapping.The achievable power savings depend on the operating conditions of the precipitator, and they usually vary during operation.The system shown in this paper is designed to keep the emissions within the required range with highest priority. Anytime the emissions range can be reached with lower power, the system will drop down the power as low as possible. In coal fired power stations it has been shown that usually 30％-60％ of the electrical energy within a period of operation can be saved. This results in a reduction of CO2 gas emissions in a coal fired power station due to the resulting electrical usage savings. The power consumed in the precipitators has to be generated additionally in the generation plant.
ESP IGBT converter Energy saving
Norbert GRASS Andreas ZINTL
Georg Simon Ohm University of Applied Sciences Nuremberg Institute for Electronic Systems ELSYS,Nure Siemens AG,Dep.I IS IN E&C CIS,Erlangen,Germany
国际会议
11th International Conference on Electrostatic Precipitation(第11届国际电除尘学术会议)
杭州
英文
259-263
2008-10-15（万方平台首次上网日期，不代表论文的发表时间）