1、 Technical features of BST electric bag composite dust collector:

BST electric bag composite dust collector is a new type of high-efficiency dust collector developed by our technicians in engineering practice. It gives full play to the respective advantages of electrostatic precipitator and bag filter, and organically combines the two technologies, so that the precipitator has the advantages of stability and high efficiency, low filter bag resistance, long service life, low operation cost, simple and convenient maintenance, small floor area and so on. Widely applicable to the power industry.

2、 Product principle and structure:

1. Principle:

Firstly, the electric field area set at the front end of BST electrostatic bag filter can collect most of the dust in the smoke and dust, with a dust collection efficiency of 75%, and charge the fine dust that has not been collected at the back end through the electric field. A filter area is set at the rear end to reduce the dust concentration and meet the environmental protection requirements of 50mg / Nm3 pre charged powder. So as to achieve the function of dust pretreatment and dust classification, reduce the rising rate of filter bag resistance, prolong the ash cleaning cycle of filter bag, avoid coarse particle scouring, and finally prolong the service life of filter bag and pulse valve and improve the comprehensive utilization of fly ash. Moreover, it can loosen the dust on the surface of the filter bag, improve the air permeability and reduce the resistance. For BST electric and bag type dust collector, the flue gas inlet and outlet adopt the large chamber structure type of flat inlet and flat outlet. The body resistance is lower to a certain extent than the domestic conventional pulse bag type dust collector, and the equipment resistance loss can be guaranteed in the equipment structure.

Therefore, BST electric bag composite dust collector can reduce the resistance of the dust collector and improve the ash removal efficiency, so as to improve the overall performance of the equipment. When the precipitation electrode and corona electrode absorb certain dust, start the top electromagnetic rapper to separate the dust from the surface of the precipitation electrode and corona electrode and fall into the ash hopper.

When the dust on the outer surface of the filter bag continues to increase, resulting in the increase of equipment resistance, when the set time or set value is reached, the control system sends a signal and the injection device starts to work

Secondly, the electric bag integration of our company integrates the characteristics of small floor area and low maintenance of the two technologies The dust removal in the electric field area of BST electrostatic bag precipitator adopts the top electromagnetic rapping technology. All rapping devices are located at the top of the precipitator. There are only cathode and anode systems in the precipitator without any transmission parts, so that the equipment has compact structure, small floor area and the same dust collection area. Compared with the side rapping, it saves 1.2m in the length of each electric field, which is conducive to the process layout. The filter bag of the low-pressure pulse rotary jet dust collector is hung on the flower board in a concentric circle. The equivalent diameter of the filter bag is 130mm and the length is 8150mm. The floor area is about 25% less than that of the conventional bag dust collector.

The anode system in the electric field area adopts c480 plate row as the precipitation electrode. The single plate is rolled by a special rolling mill in the factory, which has good overall rigidity and stability, high precision, good vibration force transmission effect and good effect of preventing secondary dust. The cathode system adopts a new type of mast type integral tubular four tooth awn wire as the corona electrode, which has high strength and stiffness, no deformation and continuous line under bad working conditions, and has a good effect of vibration force transmission. The cathode and anode systems in the electric field area adopt top electromagnetic rapping, which can be controlled to adjust the current, on-off, rapping force, rapping cycle and time sequence of the rapper, which is very simple and convenient.

Due to the adoption of highly reliable polar plates, polar wires and top electromagnetic rappers placed outside the dust and gas, the internal part of the electric field can be maintenance free for ten years, and the external part can be maintained without shutdown. Moreover, rapping realizes point-to-point control. A rapper controls the ash removal of a row of electrode plates in an electric field. If it is damaged, it can be replaced in half an hour as long as it is removed from the system It will not affect the operation of other rapping devices If side flexible arm rapping is adopted, the damage of a rapping motor will affect the operation of an electric field Therefore, the reliability of top electromagnetic rapping technology is recognized in the power plant

The dust removal of the low-pressure rotary pulse dust removal bag filter is provided by the ground roots blower, so the dust removal system is self-contained. Under normal conditions, two roots blowers can meet the dust removal requirements, and the other one is standby. There are four combined ash cleaning arms on the rotating air duct, and there are different numbers of nozzles on the ash cleaning arm. The rotating ash cleaning pipe rotates continuously to complete the back blowing and ash cleaning of the filter bag. Since the rotating arm of pulse ash cleaning can rotate freely by hand, the cloth bag and bag cage can be easily taken out and loaded. Unlike other fixed pulse bag filters, the pulse jet pipe needs to be removed first, while the conventional pulse filter needs to remove the jet pipe to replace the filter bag, and the jet pipe needs to be reinstalled and positioned, The equipment can only operate and rotate the injection. After individual filter bags are damaged, the holes on the flower plate can be covered with a prepared cover plate, which is very convenient for maintenance. However, the conventional fixed pulse bag filter can not achieve this function It can be said that the overhaul and maintenance of low-pressure rotary pulse ash cleaning bag filter has won valuable time for the power plant and improved the efficiency of the power plant

2. Structure:

The body structure of BST electric bag composite dust collector is mainly composed of shell, inlet and intermediate air flow distribution device, sedimentation electrode system, corona electrode system, rapping system, flower plate device, bag cage and filter bag, rotary jet ash cleaning system, electrical and automatic control system, etc.

3、 BST electric bag composite dust collector has the following characteristics:

1 due to the combination of the advantages of electrostatic precipitator and bag filter, it is not limited by coal and dust, and greatly improves the capture efficiency of fine particles. The precipitator has wide application range, high dust removal efficiency and large air volume, which can effectively control PM2 5 and PM10 to avoid air pollution by inhalable particles;

2 due to the charging phenomenon of the dust in the bag dust removal area, the particles of the dust layer on the outer surface of the filter bag are arranged orderly and the structure is loose, so the resistance is effectively reduced. Because the resistance of the electrostatic precipitator area itself is smaller, the precipitator can maintain low operation resistance;

3. The dust collector can not only ensure that the discharge concentration at the outlet is lower than 50mg / Nm3, but also reduce energy consumption and operation cost due to low operation resistance and long ash cleaning cycle; At the same time, the ash cleaning frequency is reduced, the service life of the filter bag is prolonged, and the replacement time of the filter bag is prolonged;

4. The structure is compact, the floor area is small and the layout is flexible. The bag filter can realize non-stop maintenance during load operation, which improves the operation rate of the filter;

5. The rotary jet bag type dust collector is adopted in the bag area. The number of pulse valves is small, the jet device can rotate freely, and the filter bag is easy to disassemble and maintain.

The specific structural features are as follows:

(1) The structure of the precipitation electrode adopts c480 plate, which has good electrical characteristics, high dust collection effect, uniform distribution of rapping force, small transmission attenuation and prevention of secondary dust. The precipitation electrode has high reliability.

(2) Corona wire has high strength and stiffness, and has good electrical characteristics to achieve high field strength. The corona pole is a simple structure that connects the rigid pole line and bottom directly with a beam, which completely eliminates the unreliable problems of wire breakage, tooth loss, deformation and so on commonly used in China, such as RS barbed wire, sawtooth wire and Star wire. Therefore, the corona pole is highly reliable.

(3) The top electromagnetic rapping is adopted for the ash removal of sedimentation electrode and corona electrode, and it is completely placed outside the flue gas. The rapping acceleration and rapping force generated on the polar plate and polar line conform to the ash collection and falling off law, that is, it is evenly distributed and transmitted from top to bottom and from large to small. The vibration force, vibration frequency, vibration intensity and period can be adjusted at any time to achieve good results. It can effectively control the secondary dust generated during rapping and ash cleaning, resulting in the problem of exceeding the emission standard during ash cleaning, and each rapper can be repaired and replaced without shutdown, which can ensure the high and reliable operation of the rapping mechanism.

(4) Maintenance free in the electric field: because there are only two parts of precipitation electrode and corona electrode in the electric field, without any rotating and transmission components, and the structure of precipitation electrode and corona electrode has sufficient strength and stiffness, it is highly reliable, so it can be maintenance free under normal working conditions.

(5) In addition, the electrostatic precipitator has the characteristics of reliable operation when dealing with highly corrosive flue gas, compact structure, less land occupation, material saving, low steel consumption, convenient maintenance and repair, etc.

(6) Rotary pulse back blowing

The dust cleaning of the filter bag is the compressed air in the air storage tank. Since the pressure difference signal of the automatic measuring dust collector is transmitted to the PLC, the PLC starts the selection program, opens the solenoid valve and starts the pulse valve. The end of the compressed air is injected into the concentric cloth bag on the flower board through the nozzle on the rotary injection arm for on-line dust cleaning. The rotation of the rotating arm is realized by the driving device of the rotating injection device.

Three ash cleaning control modes are adopted for the ash cleaning of the filter bag: differential pressure automatic control, time control and manual control. During the normal operation of the equipment, the automatic control of differential pressure is mainly used, supplemented by time control, and the manual control is generally used in the commissioning and maintenance of the equipment.

(7) Dust cleaning control process of dust collector

Among the three ash cleaning control modes of the dust collector, in order to adapt to the change of dust load on the filter bag and ensure the dust removal resistance of the filter bag, the total differential pressure signal of the dust collector measured automatically is transmitted to the PLC, and the PLC will start the slow, normal or fast pulse ash cleaning mode according to the differential pressure, so that the pulse valve sends the ash cleaning command.

The pressure difference, pulse time and pulse interval of slow, normal and fast pulse ash cleaning of the dust collector are shown in the table below

Total pressure difference between inlet and outlet	Ash cleaning mode	Pulse time	Pulse interval
0.8~1.20KPa	Slow	200ms	1-5 points
1.21~1.50KPa	normal	200ms	10 ~ 60 seconds
＞1.51KPa	fast	200ms	4-5 seconds

In the above table, pulse time: refers to the time from the opening of the pulse valve diaphragm to the closing of the pulse valve diaphragm when compressed air is injected into the filter bag for ash cleaning

Pulse interval: the time interval between two pulses.

When the total pressure difference between the inlet and outlet of the dust collector is greater than 1.51kpa, the rapid ash cleaning film type is adopted in order to quickly reduce the resistance of the dust collector. When the rapid ash cleaning still fails to reduce the differential pressure of each room and enters the normal mode of ash cleaning, the PLC will give an alarm. At this time, the personnel on duty should check the process conditions and whether the differential pressure rises due to the process conditions.

The control of the rotary injection mechanism, filter bag dust cleaning, ash hopper heating, temperature measuring elements, material level meter and inlet and outlet exhaust valves of the bag type dust remover are completely completed by the PLC cabinet and control cabinet of the dust remover, and timely monitor the changes of the pressure difference, temperature, humidity and dust concentration of the bag type dust remover.

4、 Use of dust collector

Commissioning of dust remover: before the trial operation of dust removal equipment, the following controls shall be implemented, and any defects shall be discharged in time.

1. Contents of structural adjustment

1) Clean the objects inside and outside the shell, and clean up the welding slag, iron wire and other sundries.

2) Check the electric field: check the pole distance (same pole and different pole) of each row in the electric field with a ruler to see whether it meets the design requirements. At the same time, check whether there are sundries in the electric field. No small things are allowed to hang on the pole plate and pole line.

3) Check the cathode, anode and air distribution rapping device to see if they meet the technical conditions required for installation.

4) Check the ash hopper, adjust the ash discharge valve and ash conveying equipment, clean the ash hopper, start the star ash unloading valve and ash conveying equipment to see whether the rotation is normal.

5) The spring circlip at the filter bag opening shall be closely matched with the flower plate hole The bag cage and filter bag shall be installed properly. The filter bag shall not be twisted along the direction of the bag cage. Between the filter bag and the bag cage, the filter bag and the inner wall of the shell shall not contact each other.

6) The distance between the nozzle of the rotating arm and the flower plate shall be controlled within 100 + 5mm.

7) The valve switches on the compressed air pipeline are open, and the switches on the air storage tank are open and close to the atmosphere. The connection between the compressed air pipeline and the air storage tank, the connection between the pulse valve and the air storage tank and the connection between the air storage tank and the rotary injection device shall be fastened and sealed, and the pipeline shall not accumulate water or water.

8) If the pulse valve leaks compressed air, it will produce hissing sound. The diaphragm and tightness of the pulse valve should be controlled.

9) The inlet and outlet baffle valves are set in the open state.

10) The safety valve on the blower is set at 102kpa, the high-pressure release valve of the pulse air pipeline is set at 95kpa, and the ash cleaning pressure is set at 85kpa. The flow direction of various valves is consistent with the direction indicated by the arrow.

11) The rotating arm of the rotary injection device rotates clockwise.

12) The air leakage rate shall be ≤ 3% according to the actual measurement, otherwise it shall be checked and blocked.

13) Adjust the opening rate of the distribution board. The user should see whether it meets the design requirements according to the measured air distribution. If it does not meet the requirements, the holes should be blocked evenly to make the air velocity distribution into the electric field basically uniform, and then the flue gas can be allowed to enter.

2. Adjustment contents of electrical part

1) Preliminarily determine the electromagnetic rapping system and adjust the controller.

2) Check and adjust the air sealing system to ensure that the temperature in the feed box and insulation box is 10 ℃ higher than the dew point temperature of flue gas.

3) Adjust the spark frequency according to the nature of flue gas and the requirements for the efficiency of dust collector.

4) Check whether the bag dust removal procedure is normal.

5) Whether the linkage of all electrical equipment operates normally.

6) Check the grounding resistance of the equipment. It is qualified if it is less than 2 ohms.

3. Test run of dust collector

(1) in order to ensure the operation reliability of the electrostatic precipitator, the test run shall be carried out after installation, before formal production or before the machine is stopped for a long time and reused.

(2) the test run shall be carried out according to the following steps

a) Check whether each part of the electrostatic precipitator is in good condition, whether the electrode spacing is accurate, whether there are sundries between the electrodes, whether the grounding of each part is reliable, whether there is really no one in the dangerous area of the equipment, whether each inspection door is closed before power transmission, etc.

b) Start the ash discharge device for one hour and check the operation of the ash discharge device.

c) Start rapping for half an hour and check the working conditions of all links.

d) Check whether the transmission mechanism of rotary injection device operates normally.

e) Check whether the opening and closing action of the inlet and outlet baffle valves of each chamber is flexible, and try and check one by one.

f) Observe and record the inlet and outlet pressure difference of bag filter and the upper and lower pressure difference of flower plate.

g) Check the operation and pressure release of Roots blower for ash cleaning.

h) Check whether the pulse valve operates normally.

i) Check whether the electric heater of the ash hopper and the gasification device at the bottom of the ash hopper are normal.

j) Solve all the problems found in the above steps.

k) Check whether the electrical wiring of each part of the main circuit of the electrostatic precipitator is correct.

l) Check whether the power network voltage is normal.

m) Check whether all grounding parts are grounded and whether the grounding resistance meets the requirements.

n) Check the execution of PLC control program.

o) Solve all the problems found in the electrical inspection. At this time, there is an open circuit between the anode and cathode.

p) Adjust the secondary voltage to the point, adjust the spark frequency to small, and start the air sealing system.

q) Power on, close the automatic adjustment system and observe the rise of no-load voltage. It shall be able to slowly rise to the rated voltage and observe the corona in the electric field.

r) If the above test is successful, the flue gas meeting the service conditions can be sent into the electric field, and the working conditions of voltage, current and automatic control system can be observed. At this time, the current gradually increases and the voltage slightly decreases. The spark frequency can be adjusted to an appropriate value according to the situation.

s) Check the top cover, inlet and outlet horn, ash hopper, manhole door, ash discharge valve and side plate for air leakage.

t) After shutdown, eliminate the faults found during commissioning, and then officially put into production.

4. Operation of dust collector

(1) preparation before startup

a) Check whether all parts of the equipment are in good condition, whether the electrode spacing is accurate, whether there are sundries between the electrodes, whether the operation part of the equipment is flexible, whether the grounding of all parts is reliable, whether there is no one in the dangerous area, and whether the door has been tightened and locked before power transmission.

b) Pre spray the bag filter first.

c) Check whether the system operates normally.

d) Whether the flue gas temperature and humidity at the outlet of the boiler are within the design range.

e) Check whether the lower ash discharge system of the dust collector operates normally.

f) 1 ~ 2 hours before the start of the dust collector, start the heating device of the ash hopper of the dust collector, and the temperature of the ash hopper shall not be lower than 90 ℃.

(2) startup procedure of dust collector

a) Start the top heating system of electrostatic precipitator.

b) Start the cathode and anode rapping devices.

c) Start the induced draft fan and open the flue gate.

d) Turn on the bag by-pass device when adding oil for combustion support at the beginning

e) After the coal-fired boiler completely burns coal for 2 hours, connect the high-voltage power supply and remove the grounding at the same time.

(3) closing system of dust collector

a) First cut off the switch of induced draft fan until it stops.

b) Cut off the power supply of the high-voltage rectifier.

c) Disconnect the high-voltage switch and ground the high-voltage cable.

d) Close the bag cleaning control system.

e) The inlet baffle valve is closed.

f) The rapping of the cathode and anode rapping devices of the electrostatic precipitator must be stopped after cutting off the power supply of the electrostatic precipitator for a period of time (generally 3 ~ 4 hours).

g) Stop ash conveying and close the ash discharge valve.

h) Keep the driving motor of Roots blower and rotating mechanism and start the circulating ash cleaning program. In case of short-term shutdown, this operation is not required.

V. repair and maintenance

To maintain the high efficiency of the electrostatic precipitator depends largely on the quality of maintenance and management. The maintenance and management of the electrostatic precipitator is a highly demanding work, which must be in the charge of a specially assigned person, and the rules and regulations must be strictly implemented and overhauled regularly.

1. Inspection and management during operation

(1) the temperature rise of high-voltage rectifier, alternating current transformer and motor is normal, the oil temperature shall not exceed 70 ℃, and there is no abnormal sound.

(2) the ash discharge valve operates normally, the bearing lubrication is sufficient, and there is no ash accumulation in the ash hopper.

⑶ the over-current protection power circuit of the ash discharge valve motor is in good condition.

(4) the rapping device shall be in good condition without abnormal sound.

(5) the temperature rise of each rotating motor is normal without abnormal sound.

(6) the lubricating oil level of the transmission is normal without abnormal sound.

(7) adjust the "rising rate", "falling rate" and "current limit" of operating voltage according to the condition of flue gas workpiece to make it work at the value.

(8) record the electrical operation parameters once every hour.

(9) in case of abnormality, it shall be handled and recorded in time.

(10) keep the site and equipment clean and sanitary, and wipe the porcelain bushing regularly.

2. Regular maintenance

(1) the HV and LV rectifier bushings shall be wiped regularly every two months.

(2) clean the components and wiring terminals in the control cabinet every three months.

⑶ add sewing oil to the thyristor element and cooling fan every three months.

(4) check the electric heater once every six months. If it is damaged, replace it in time.

(5) conduct breakdown test for high-voltage rectifier transformer 5 times a year, and the average value of instantaneous breakdown shall be greater than 35kV / 2.5mm.

(6) inspect the shell of high-voltage rectifier transformer, high-voltage cable sheath and cable head, iron frame of control panel, iron mesh door, dust collector shell and reinforcement grounding part of concrete column every year. It shall be in good contact without looseness and corrosion. At the same time, the measured grounding resistance shall not be greater than 2 ohms.

The bag filter shall be operated on the basis of the given design chart, and special attention shall be paid to working at the temperature of 15-25 ℃ above the dew point of water and acid. Refer to the following table for maintenance and inspection.

Measuring point	period	Inspection contents	Note
control equipment	Daily inspection	Electrical interface, check the pressure measuring point in contact with dust	Clean the equipment and operate it by hand if necessary
Pressure through filter bag	Daily inspection	Press off and check the pressure measuring points in contact with dust	Clean the equipment and operate it by hand if necessary
Ash cleaning pressure	Daily inspection	Ash cleaning pressure, pressure increases to. During the pulse interval, the pressure is about 85-100kpa	Check the pressure indication of the pulse air tank and close the inspection valve after the test
control	Weekly inspection	Electrical connection, test lamp
Manhole door to air purification chamber	Weekly inspection	Gasket and close tightly
Ash conveying and unloading	Weekly inspection	Operation and gas seal
Inlet and outlet baffle valve	Weekly inspection	Proper operation of gas seal and compressed air equipment	Replace the gasket if necessary
Roots blower, fan	Weekly inspection	Safety valve (close the outlet valve) check the opening oil level of the outside valve	In case of overtemperature, the compressed air switch is closed by PLC, and the air compressor is automatically converted to another one by PLC
Rotary arm drive	Monthly inspection	Check the air tightness of the oil seal of the drive motor and the gasket of the rotating arm	Replace the gasket if necessary
Solenoid valve	Monthly inspection	Air leakage
Pulse valve	Monthly inspection	Net gas leakage of pulse valve	The damaged pulse valve is recorded in the PLC to check whether the diaphragm is damaged
Ash hopper electric heater and gasification board	Monthly inspection	Bolt connection, tightness and tightness of the device. Observe whether the control cabinet is powered off again and the ash cleaning is not smooth	Replace it if necessary and tighten the bolt seal
Filter bag	Quarterly inspection	Tightness between flower board and bag. Check the bag for damage (accumulation of ash on the flower board)
Rotating arm	Quarterly inspection	The distance between the fixed nozzle and the flower plate is 100mm (error + 5mm)	Adjust if necessary
Dust concentration in clean gas	Quarterly inspection	Open the air purification chamber one by one to selectively check the ash condition

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