Steam boiler bag filter

Steam boiler bag filter

1. Overview of bag filter for steam boiler
The steam boiler bag filter is the new technology achievement of Yancheng Leijin Environmental Protection Technology Co., Ltd. Technology R&D Center. The steam boiler bag filter is a unit combined type dust removal equipment with large air volume, good ash removal effect and reliable operation. Steam boiler bag filter is widely used in the flue gas dust removal and material recovery of boilers, kilns, waste incineration in electric power, metallurgy, building materials, chemical and other industries.
2. Working principle of bag filter for steam boiler
The dust-laden gas of the steam boiler bag filter enters the ash hopper of each unit through the diversion pipe. Under the guidance of the ash hopper diversion system, the large particle dust is separated and directly falls into the ash hopper. The clean gas after passing through the filter bag is discharged through the upper box, poppet valve and exhaust pipe. With the progress of filtration, when the dust accumulation on the surface of the filter bag reaches a certain amount, the ash cleaning control device closes the poppet valve according to the set procedure, opens the electromagnetic pulse valve to blow, shakes off the dust on the filter bag, and falls into the ash hopper It is discharged through the ash discharge valve.
This series of dust collectors are equipped with a bypass flue. When the boiler (or incinerator) starts, the bypass flue is opened to prevent the oil from burning badly when igniting, and the oil sticks to the filter bag, and the filter bag is burned in case of an open flame. . When an accident occurs in the boiler, the exhaust gas temperature exceeds the allowable temperature of the filter bag, and the bypass is opened.
The steam boiler bag filter is also equipped with a leak detection device, which consists of multiple probes (one for each compartment) and an air cannon in the ash hopper.
basic structure
The steam boiler bag filter is composed of box assembly, filter bag assembly, diversion device, pulse injection system, ash discharge system, control system, offline protection system, etc.
1. The box part of the bag filter for steam boilers: consists of upper box (clean air chamber), middle box (filter room), lower box (ash hopper), flue gas distributor, flower plate, platform, escalator, feet , air inlet, ash outlet, thermal insulation, color panel and other components.
2. The filter bag assembly of the steam boiler bag filter: the connection design of the filter bag frame, the cloth bag and the hanging bag adopts a self-locking device, which is convenient for installation and replacement, and can effectively prolong the service life of the filter bag. The specifications of the filter bags are: φ130x6000mm, φ160x6000mm, φ160x7000mm, using polyphenylene sulfide needle-punched felt (imported PPS/PPS504CSl7, waterproof and oil-proof).
3. Diversion device of bag filter for steam boiler: adopt the international air intake method and design a unique flue gas distribution device, which can not only effectively distribute dust-containing gas, but also separate large particles to avoid dust-containing gas scouring the filter bag. Further improve the dust removal efficiency and prolong the service life of the filter bag.
4. Pulse injection system of steam boiler bag filter: recoil header, electromagnetic pulse valve, pressure joint, nozzle tube, bracket, etc. Specifications below HGDM-5.6 are the whole box cleaning, and the other specifications have a compressed air nozzle pipe on the upper part of each filter bag. During operation, it is generally set that each row of filter bags is pulsed to clean the dust once every 10S, and the solenoid valve is activated regularly to spray the pulse back-blown compressed air into the filter bags for dust removal.
5. Ash output system of bag filter for steam boiler: It is composed of electric vibrator (air cannon), electric heater, ash level indicator, and electric vibrator (air cannon) ensures that the dust has good fluidity.
6. Steam boiler bag filter control system: It is mainly composed of pulse injection controller, PLC computer control cabinet, thermal resistance thermometer, static pressure measuring point, material level indicator and measuring element.
7. Off-line protection system of bag filter for steam boiler: It is mainly composed of bypass valve, differential pressure device, material level meter, thermometer, pressure detection device, pulse controller, filter bag leak detection device, etc. Spray water when the flue gas temperature is too high or when the boiler is re-burning, so as not to burn out the filter bag. There is a filter bag leak detection device composed of a differential pressure gauge in the clean air chamber, so that the filter bag can be alarmed in time when it is damaged. Because the large-tonnage boiler needs to spray fuel during ignition and low load, a large amount of oily gas will be generated, and the flue gas will directly enter the dust collector, which will cause the powder layer of the filter bag to harden, increase the resistance of the system, and affect the normal operation. A bypass pipeline is added to the system, so that the oil-containing gas is discharged through the bypass pipeline at the moment of fuel injection, thereby effectively protecting the filter bag.
3. Main technical parameters of steam boiler bag filter

4. Design interface and supply scope of bag filter for steam boiler
1. The inside of the inlet flange of the dust collector is designed and supplied by our company, and it is equipped with a flange.
2. The feet of the dust collector and the bottom plate are designed and supplied by our company, and are of civil type without outriggers.
3. The dust collector ash conveying equipment is generally designed and supplied by our company, and the special case is determined by the process design of the dust collector system.
4. The dust collector body is grounded for lightning protection, and the lighting is designed by our company and borne by the user.
5. Main body and filter system: main body, filter bag, cage frame, offline valve, manual switching valve.
6. Ash cleaning system: electromagnetic pulse valve, pulse controller, blowing system.
7. Ash unloading system: air cannon for clearing blockage, ash unloading valve, flapper valve, ash hopper heating system.
8. Protection system: bypass valve, leak detection device.
9. Control system: differential pressure gauge, thermometer, material level gauge, main control cabinet, on-site control cabinet


Steam boiler bag filter, selection precautions
1. For coal types that are difficult to collect by electrostatic precipitators (such as coal with SiO2+AI203>85%, coal with extremely low sulfur content in coal, and coal with too high specific resistance), a bag filter should be used.
2. If the concentration of smoke and dust is less than 50mg/Nm3, it is necessary to use an electrostatic precipitator with more than four electric fields, and a bag filter should be used instead.
3. For units that have already been built. If the original unit adopts water dust collector, multi-tube cyclone dust collector and other dust removal equipment with high resistance, the induced draft fan may not be replaced; if the original unit uses an electrostatic precipitator, the induced draft fan needs to be replaced or modified.
4. In the project of transforming the electrostatic precipitator into a bag filter, the internal structure of the precipitator body can be partially removed, and the shell, heat preservation and ash conveying devices can be retained to reduce the transformation cost.
5. When it is used to deal with dusty gas with high relative humidity, heat preservation measures should be taken to avoid "paste bag" caused by condensation; when it is used to purify corrosive gas, appropriate corrosion-resistant filter material should be selected; When dealing with high-temperature flue gas, cooling measures should be adopted to reduce the temperature of flue gas to below the temperature that the filter bag can withstand for long-term operation, and high-temperature-resistant filter materials should be used as much as possible.
6. For high-sulfur coal, desulfurization technology should be adopted. The method of low tonnage boiler and low input is to adopt the method of calcium injection desulfurization and pipeline spray drying in the furnace. The chemical reaction of this method can be extended to the filtration process and ash conveying process of the bag filter, and the sulfur content index of the exhaust gas can meet the national requirements. standard.