The test of different high voltage power supply for the wet electrostatic precipitator
2016-02-03 11:43:02
Author: Weng Lingang Chen Hongjian Ye Huaiyong Li Bingcheng
Abstract this article through conductive glass steel honeycomb type wet electric dust collector test platform, using different high voltage power supply application case, gives the wet dust collector in the state of the electrical parameters of no-load, load, and the spray washing.
1 Preface
At present, the increasingly strict environmental emissions to promote the development of flue gas purification technology. The de NOx, dust removal and desulfurization of flue gas residual fine particles escape and liquid mist entrainment of environmental impact, has become the object of attention and wet dust collector can effectively collect such fine dust and aerosol, will become the preferred equipment for flue gas deep processing.
Wet electrostatic precipitator and the basic principle and conventional dry electrostatic precipitator of the same, but to overcome the dry electric dust cleaning dust than the shortcomings of the scope of application of the resistance, water cleaning to avoid the secondary dust, has very high dust removal efficiency. At present, its structure mainly has two kinds of horizontal and vertical modes. One tube type wet precipitator and electrical in mist eliminator is very similar, the structure closer in the chemical system in sulphuric acid production process using the electric demister, the main features are high flow velocity and saturated wet flue gas, corrosion resistance and ultra low emissions.
Wet electrostatic precipitator dust cleaning by spray cleaning, lead to work in often flashover and short circuit, because most of the tube type wet dust collector anode is made of conductive glass steel and its conductive properties to much weaker than that of the electrostatic precipitator of metal material, the ability of tolerance spark discharge and arc discharge is much weaker in the electrostatic precipitator of metal material.
The variation of the performance of the wet electrostatic precipitator, and puts forward the special and higher requirements for the high voltage power supply technology.
2 wet electrostatic precipitator test bench
2.1 general situation of test bed
Wet electrostatic precipitator test sets of anode dust collection electrode adopts is hexagon inscribed circle diameter 300mm conductive glass steel, the effective length of 4.5m, 37 bundle composed of a module, collecting area 173m2, cathode line the jagged line of lead and lead antimony alloy, gas chamber with carbon steel and glass steel anti-corrosion treatment process. Spray washing cleaning is set to once a day, 0.5 tons of water per time.
In order to meet the test bench test, two different types of high voltage power supply, 100mA/72kV power frequency constant current source and the 200mA/72kV AM FM high-frequency power supply, respectively.
2.2 design parameters
Application situation: the production of furnace flue gas by denitrification catalyst
Degree management
Ingredients: smoke dust, aerosols and droplets
Gas volume: 10000 /h M3
Flue gas temperature: 50-70 degree C
Inlet concentration: 55 Nm3 mg/
Outlet concentration: less than 5 Nm3 mg/
Dust removal efficiency: 90%
2.3 test results
Emission concentration: 4.3 Nm3 mg/
Equipment resistance: 185Pa
The droplet removal rate: 78.7%
3 wet electrostatic precipitator operating data
3.1 power frequency constant current source
Power frequency constant current source high voltage DC power supply control process is through the change trend of the operating voltage feedback and preset values for comparison, in order to determine the amount of L-C input. Its not too many electronic components, has the advantages of simple structure, high reliability; strong impact resistance, transient and steady-state short-circuit withstand, input and output voltage for sine wave, amplitude modulation control method, high conversion efficiency, does not interfere with the power grid.
Power frequency constant current source used in the chemical industry in the early stage of the application of electric mist sprayer, wet ESP has application case.
3.1.1 no-load operation
Table 1 power frequency constant current source no-load boost data
Power frequency constant current source maximum allowable overload 20%. The two current can be run in 120mA.
From the table 1 can only see 5 sets of data, which is because
100 mA power supply has 5 stalls, that is, when the power supply running only 5 state selection. Large capacity power file up to dozens of files.
Table 1 shows all the input, the two voltage 45kV, the two current 108mA。
Fig. 1 no-load V/I curve of power frequency constant current source
3.1.2 band load
Table 2 power frequency constant current source with load boost data
Table 1 and table 2 show that the running data of the two are very close, which shows that the load characteristics of wet esp in cold and hot state are very close to. The choice of line current density of wet ESP is generally more than 0.6mA.
3.1.3 spray irrigation
As shown in figures 3 and 4, open spray washing, pipeline pressure set for 0.2-0.25mPa, about 5 seconds after the electric field flashover discharge, detection power to discharge, step by step down operational parameters of electric field, voltage stability in a region, in the meantime electric field is still sporadic discharges occur.
After the spray irrigation is over, the power supply is automatically returned to the original set parameters.
The two voltage can be maintained at about 25kV during the spray rinsing.
Fig. two 3 current in spray cleaning
Fig. two 4 voltage of spray cleaning
3.2 high frequency power supply
In order to compare with the constant current source amplitude modulation mode, the high-frequency power supply of the specially selected amplitude modulation mode is compared. Amplitude modulation high-frequency power and conventional power frequency difference is the bus voltage regulation mode control input transformer voltage and the current waveform is continuous, is only the magnitude of the change, frequency and constant current source similar to and different from conventional FM high frequency power supply. This is conducive to the demand for large current wet electrostatic precipitator.
Fig. 5 no load V/I curve of high frequency power supply
3.2.1 no-load operation
Table 3 no load boost data for high frequency power supply
Note: Table 3 and table 4 are listed only when the same capacity of the power frequency constant current source is listed.
When the rated capacity is released, the two current can reach 300mA, and the two voltage is up to 61kV.
Table 4 and table 3 once again can see the two running data is very close, which shows that the wet esp in the cold and hot state run no matter what high voltage power supply, its load characteristics are very close.
3.2.2 With load
Table 4 high frequency power supply with load boost data
Fig. 6 V/I curve of high frequency power supply with load
3.2.3 spray irrigation
Fig. two 7 current in spray cleaning
As shown in Figure 8 figure 7, after opening the spray rinse, the flashover discharge, high frequency power supply detection after discharge, also use step by step down the electric field operation parameters to avoid the electric field discharge.
After the spray irrigation is finished, the high frequency power supply is automatically returned to the original set parameters. The curve of the recovery process is relatively smooth with power frequency constant current source.
The two voltage can be maintained at about 25kV during the spray rinsing.
Fig. two 8 voltage of spray cleaning
4 Summary of operation test of wet electrostatic precipitator
4.1 wet electrostatic precipitation is due to the operation of the saturated water vapor, the conductive medium is water molecules, so the running current is very large, and it is almost identical with the load current. So the choice of high voltage power supply should choose the power supply of the current, power frequency constant current source and am high frequency power supply is a kind of power supply.
4.2 the choice of wet electrostatic precipitator power supply should be based on current, the test bench with the mode of the line current density up to 0.7mA/m, high frequency power supply can even up to 1.5mA/m.
4.3 wet electric dust collector due to the presence of the influence of spray and water vapor, resulting in operation process are prone to flashover and instantaneous short circuit phenomenon, so the supporting high-voltage power supply should have the strong ability of anti short circuit impact, power frequency constant current source and high frequency power relative to other power has a good advantage.
4.4 under the same conditions, we can see that the amplitude modulated high-frequency power supply is more than the power frequency constant current source, the same voltage is 1.2 times the power frequency constant current source. This is beneficial to improve the efficiency of dust collection.
4.5 the power frequency constant current source with respect to the high frequency power supply, its to the flashover control ability is obviously weaker than the high frequency power supply, the spark control method has certain limitation to the situation request high situation.
4.6 wet electrostatic precipitator high voltage power supply should fully consider the water spray system on the impact of high pressure to minimize the influence of spray voltage on the removal efficiency, for flashover recovery time and recovery voltage and dry electric dust removing different, should try to avoid even the flash and tripping phenomenon occurred.
5 concluding remarks
Through the wet dust collector test bench test and the supporting high-voltage power supply characteristics with preliminary qualitative understanding; for tube type wet precipitator polarity and to choose the style of line current density with more accurate understanding; test data for use in large scale wet electrostatic precipitator has certain reference role. As for the wet electrostatic precipitator, the high voltage power supply with high current capacity should be used for further experiment and exploration to meet the high efficiency of dust collection and the purpose of energy saving.
reference
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