Comparison of Performance of Electrostatic Precipitator and Bag Dust Collector in Thermal Power Plant
1. Dust removal efficiency
Bag filter than the electrostatic precipitator has a higher, more stable dust collection efficiency, especially for the human body has a serious impact on heavy metal particles and submicron dust particles to capture more effective. Usually, the dust removal efficiency of up to 99.9% or more, the concentration of dust can be stable below 50mg / Nm3, or even up to 10mg / Nm3 or so, almost zero emissions. So low emissions, visual inspection is not seen the smoke on the chimney discharge.
2. Effect of coal and boiler system changes on the dust collector
2.1 if the amount of wind unchanged, soot changes
Bag filter: the same concentration of emissions, cleaning frequency change (automatically adjustable).
Electrostatic precipitator: dust removal efficiency changes, the emission concentration changes.
2.2 if the amount of dust remains the same, the air volume changes
Bag filter: equipment resistance increases with the increase in air volume, filtration wind speed progress, dust removal efficiency basically does not affect.
Electrostatic precipitator: equipment resistance is not affected, dust removal efficiency increases with the air volume are very obvious.
2.3 if the temperature changes
Bag dust collector: too low smoke condensation may cause "paste bag" and shell corrosion, the smoke temperature is too high than the filter temperature is easy to "burn the bag" and damage the filter bag, but the temperature caused by these consequences is extreme temperature (Accident / abnormal state), it is necessary to do a good job of dust protection measures. But the flue gas temperature as long as the selected filter to withstand the temperature range, does not affect the dust removal efficiency.
Electrostatic precipitator: too low smoke temperature condensation will cause shell corrosion or high voltage creep, flue gas temperature directly than the resistance, thus affecting the dust removal efficiency, and the impact is more obvious.
2.4 flue gas chemical composition (or burning coal) changes.
Bag filter: the filter to adapt to the scope of the conditions, no effect on the dust removal efficiency.
Electrostatic precipitator: flue gas chemical composition of direct dust than the resistance, thus affecting the efficiency of dust, and a great impact.
2.5 air distribution
Bag filter: dust removal efficiency and air distribution have nothing to do, but the local airflow can not be too much deviation, otherwise it will be due to uneven load or jet wear caused by the local broken bag.
Electrostatic precipitator: A very sensitive electric field in the air distribution, airflow distribution directly affects the level of dust removal efficiency.
2.6 air preheater and system pipeline air leakage.
Bag filter: poor resistance to the poor performance of the filter will affect the bag life, such as RYTON filter, but the dust removal efficiency is not affected.
Electrostatic precipitator: equipment resistance no significant change, but the increase in air volume is equivalent to increase the wind speed, the efficiency of dust efficiency has an impact.
3. Operation and governance
Bag filter: stable operation, simple control, no high-voltage equipment, good security, and boiler operation with close, strict management requirements.
Electrostatic precipitator: interference in the operation of many factors, the control is relatively complex, high-voltage equipment, high-security requirements. Boiler operation requirements are not high, but strict equipment management requirements.
3.2 downtime and start
Bag filter: convenient, long-term outage need to do a good job of protecting the bag.
Electrostatic precipitator: convenient, can be shut down at any time.
3.3 inspection and maintenance
Bag filter: maintenance workload is small, can achieve a non-stop test, three or four years to replace the filter bag workload is relatively heavy.
Electrostatic precipitator: maintenance workload is relatively large, the test must stop.
4. Equipment investment
4.1 for the conventional flue gas conditions and dust (mainly refers to the electrostatic precipitator more suitable for flue gas), the two dust collector discharge concentration to achieve the current low environmental requirements: the initial investment bag dust collector than electrostatic precipitator about 20 ~ 40% or so.
4.2 for low sulfur high specific resistance dust, high SiO2, Al2O3 class is not suitable for electrostatic precipitator dust collection, two kinds of dusters to achieve the current lower environmental requirements (200mg / Nm3): the initial investment electrostatic precipitator and bag Large dust collector or electrostatic precipitator investment is high. For typical coal types, such as the Zhungeer coalfield and sea wave bend coalfield, electrostatic precipitator investment is higher than the bag filter.
4.3 under normal conditions to achieve the same efficiency of dust removal or to achieve the same discharge concentration, electrostatic precipitator investment than bag filter investment. Take power plant 200MW unit as an example:
5. Running energy consumption
5.1 running energy consumption
Bag filter: wind energy consumption, cleaning system energy consumption is small.
Electrostatic precipitator: wind energy consumption is small, electric field corona energy consumption.
However, the overall cost of the two kinds of dust collectors. For the electrostatic precipitator is difficult to capture the dust, or when the electric precipitator reaches or exceeds the number of the electric fields, the energy consumption of the electrostatic precipitator is significantly higher than the bag filter.
5.2 the economic benefits of dust emissions
In actual operation, the concentration of the bag filter is only about 10% of the electrostatic precipitator. Therefore, the sewage charge for the power plant is about 10% of the electrostatic precipitator. In accordance with the current state of the collection of sewage charges, the use of bag filter after each furnace / annual sewage charges paid part is quite considerable, at least millions to millions of dollars.
In addition, the bag filter has about 15% of the desulfurization efficiency! This can reduce SO2 emissions, the same to reduce the sewage charges.
5.3 maintenance inspection costs
Bag filter maintenance inspection costs are mainly about four years of the filter bag replacement fee, from the current actual operation situation, a filter bag replacement costs only need 1.5 to 2 years of sewage charges less than the electrostatic precipitator Part of the payment can be paid.
Electrostatic precipitator maintenance inspection costs are mainly on the anode plate, cathode line and vibration hammer, ceramic and other parts of the replacement. This is more expensive, but the cycle is relatively long.
Note: Compared with the electrostatic precipitator, the bag filter is less than 2 years of accumulated savings due to the efficiency and efficiency of the dust removal efficiency and energy consumption. It is sufficient to make a full replacement of the filter bag. In fact, the bag filter bag replacement is about 4 years, therefore, for the power plant for the use of bag filter from the economic benefits of environmental protection, is the flow of funds is.
6. For circulating fluidized bed boilers
6.1 circulating fluidized bed boiler outlet dust concentration is high, at the same time due to increasing the amount of calcium base, a direct result of the dust than the resistance increases, high specific resistance to electrostatic precipitator dust is quite unfavorable.
6.2 circulating fluidized bed The flue gas from the outlet of the boiler has removed a significant amount of SO2, which has also led to an increase in the specific resistance of the dust, which is also unfavorable to the electrostatic precipitator.
6.3 for the dust concentration is high, the resistance is very high, very low sulfur smoke dust, electrostatic precipitator even if the discharge concentration of 100mg / m3 is also very difficult.
6.4 bag dust collector dust removal efficiency from the dust concentration and the physical and chemical properties of flue gas, the export concentration can be long-term stability below 50mg / Nm3.
6.5 in order to ensure that the discharge of dust collector and then increase the dust collection area, this time the power consumption of the ESP than the bag filter is much larger, the whole machine running on the progress of progress, that is to say, electrostatic precipitator The price difference is reduced.
6.6 bag dust collector efficient dust removal efficiency led to low concentrations of dust emissions in the current emissions charges, excessive fines under the environmental economic policy brought about by the direct economic benefits of electrostatic precipitators can not be compared.
In short, the efficient efficiency of bag dust collector efficiency is considerable, and this economic benefit is a long-term, stable and benign economic benefits. More important is the low concentration of emissions brought about by social and environmental benefits.