Design scheme of bag dust removal for flue gas of 10T biomass boiler

　　Design scheme of bag-type dust collector for flue gas of 10T biomass boiler I. Design overview This design is a bag-type dust collector for flue gas of 10T biomass boiler, aiming at effectively removing fine dust and pollutants from boiler flue gas and realizing environmental protection discharge. Based on the analysis of flue gas characteristics, the design selects the appropriate dust collector type, and comprehensively considers the structural design, material selection, control system design, filter material selection, installation and debugging, operation and maintenance, and safety measures to ensure the performance and reliability of the dust collector. Second, the analysis of flue gas characteristics, boiler flue gas contains high dust concentration, fine particles, and some particles have harmful substances. Flue gas temperature fluctuates greatly, moisture content is high, and it is easy to condense. According to the characteristics of flue gas, the suitable dust collector type and filter material are selected to adapt to the special conditions of flue gas. Third, the type of dust collector is selected. According to the analysis of flue gas characteristics, the bag filter is selected as the type of dust collector in this design. Bag filter has the advantages of high dust removal efficiency, wide adaptability to flue gas temperature fluctuation range and good humidity resistance, and is suitable for treating fine dust and harmful gases. Iv. structural design and material selection of dust collector The dust collector adopts pulse jet cleaning method, which is divided into filter room and clean room. The filter room includes flower board, filter bag, keel and other parts, and the material is polyester fiber needled felt with corrosion resistance, wear resistance and high temperature resistance. The clean air chamber includes pulse valve, air bag, blowpipe and other parts, and the material is carbon steel. V. Design of dust collector control system The dust collector control system adopts PLC control, and automatically adjusts the pulse cleaning cycle and injection time according to the detected parameters such as flue gas flow and pressure.Maintain the stable operation of the dust collector. At the same time, set up fault diagnosis and alarm functions to find and deal with abnormal situations in time. Selection and evaluation of filter materials According to the characteristics of flue gas, polyester fiber needled felt is selected as the filter material, which has the advantages of acid and alkali resistance, high temperature resistance, wear resistance, flame retardant and antistatic. The evaluation of filter material includes material, gram weight, air permeability, resistance, temperature resistance and other indicators to ensure that it meets the operation requirements of dust collector. Seven, installation and debugging installation process, to ensure that the structure of the dust collector is stable, the parts are closely connected. After the installation is completed, debug and check whether the electrical parts, control system and pulse ash cleaning system work normally. And the performance test is carried out to detect the inlet and outlet concentration of the dust collector to ensure that it meets the design requirements. VIII. Operation, maintenance and safety measures During the operation, regularly check whether the electrical parts, control system and pulse ash cleaning system are working normally, and find and handle abnormal situations in time. Replace the filter bag regularly to ensure the dust removal efficiency of the dust collector. Strengthen employees' safety awareness, abide by operating procedures, and ensure the normal operation of equipment and the safety of personnel. Ix. Environmental Impact Assessment and Control This design adopts a bag filter, which produces almost no noise during operation and has little impact on the environment. A small amount of waste gas produced after treatment meets the national emission standards and has little impact on the environment. The use of high-performance filter materials can effectively reduce dust emission and protect the environment. Generally speaking, according to the flue gas characteristics of 10T boiler, the design selects the appropriate bag filter type and carries out a series of optimization designs.Ensure the stable operation and efficient dust removal of the dust collector. Through comprehensive consideration of installation and debugging, operation and maintenance and safety measures, the reliability of equipment and the safety of personnel are ensured. The design also carried out environmental impact assessment and adopted a series of control measures to reduce the impact on the environment.

　　Structural design of pulse bag filter for biomass boiler;

　　Compared with the traditional boiler furnace, the boiler bag dust collector has a larger space in structural design, and at the same time, a very reasonable secondary air is arranged, which is beneficial to the full combustion of a large number of volatile substances precipitated instantly when biomass fuel is burned. The boiler can be equipped with fuel (gas) ignition burner to realize ignition automation. The feeding, combustion, slag removal, water supply and ignition of the boiler can be automatically controlled, and the operation is very convenient. The boiler is equipped with an automatic ash cleaning device, which can timely accumulate ash on the heating surface of the boiler and ensure the stable operation of the boiler. An economizer is arranged at the tail of the boiler, and an air preheater can also be arranged according to the needs of users. Compared with the traditional boiler, the boiler has high efficiency and low exhaust temperature. Using thermal insulation materials, the surface temperature of the boiler is low, and the heat loss can be ignored. It is produced in strict accordance with China codes and standards, and all pressure parts are made of boiler steel. Every boiler must undergo strict inspection and testing before leaving the factory, including hydrostatic test and X-ray detection. Manholes, inspection doors, fire observation holes, etc. are provided, which is very convenient for maintenance. Biomass boiler is characterized by energy saving, environmental protection and convenient installation and use.

　　Dust-containing gas enters the ash hopper of each unit through the diversion pipe, and falls directly into the ash hopper after being separated by the diversion system of the ash hopper. The remaining dust enters the filtering area of the middle box with the airflow, and the filtered clean gas passes through the filter bag and is discharged through the upper box, the lift valve and the exhaust pipe. With the progress of filtration, when the dust on the surface of the filter bag reaches a certain amount, the dust removal control device closes the lift valve according to the set procedure, opens the electromagnetic pulse valve for injection, shakes off the dust on the filter bag, and falls into the ash hopper and is discharged through the ash discharge valve.

　　This series of dust collectors is equipped with a bypass flue, which is opened when the boiler (or incinerator) is started, so as to prevent the head oil from burning badly, the oil from sticking to the filter bag and burning the filter bag in case of open flame. When the temperature of the boiler exhaust gas exceeds the allowable temperature of the filter bag in an accident, the bypass is opened.

　　This series of dust collectors is also equipped with a leak detector, with multiple probes (one in each chamber), and an air gun is installed in the ash hopper.

　　Basic structure

　　The pulse bag dust collector of biomass boiler is composed of box assembly, filter bag assembly, diversion device, pulse injection system, ash discharging system, control system and off-line protection system.

　　1. Box body: It consists of upper box body (clean air chamber), middle box body (filter chamber), lower box body (ash hopper), flue gas distributor, ceiling, platform, escalator, legs, air inlet, ash outlet, thermal insulation, color panel, etc.

　　2. Filter bag assembly: the connection design of filter bag frame, cloth bag and hanging bag adopts self-locking device, which is convenient for installation and replacement and can effectively prolong the service life of filter bag. The specifications of filter bags are: Φ φ1306000mm, Φ φ1606000mm and Φ φ1607000mm, which are made of polyphenylene sulfide needled felt (imported PPS/PPS504CSl7, waterproof and oil-proof).

　　3. Diversion device: The internationally advanced air intake mode is adopted, and a unique flue gas distribution device is designed, which can not only effectively distribute dusty gas, but also separate large particles, so as to prevent dusty gas from washing the filter bag, further improve the dust removal efficiency and prolong the service life of the filter bag.

　　4. Pulse injection system: recoil header, electromagnetic pulse valve, pressure-bearing joint, nozzle tube, bracket, etc. The following specifications of HGDM-5.6 are full-box dust removal, and the rest specifications have a compressed air nozzle tube at the upper part of each filter bag. During operation, it is generally set that each row of filter bags is back-blown to clean the dust once every 10S, and the electromagnetic valve is started at regular intervals to spray the pulse back-blown compressed air into the filter bags to clean the dust.

　　5. Ash discharging system: It is composed of electric vibrator (air cannon), electric heater and ash level indicator. The electric vibrator (air cannon) ensures good fluidity of dust.

　　6. 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: mainly composed of bypass valve, differential pressure device, material level gauge, thermometer, pressure detection device, pulse controller, filter bag leak detection device, etc. When the flue gas temperature is too high or the boiler tail is re-ignited, spray water to avoid burning the filter bag. The clean air chamber is equipped with a filter bag leak detection device composed of differential pressure instrument, etc., so as to give an alarm in time when the filter bag is damaged. Because the large-tonnage boiler needs to spray fuel when it is ignited and under low load, it will produce a large amount of oily gas, which will directly enter the dust collector, which will cause the filter bag powder layer to harden, increase the system resistance and affect the normal operation. Bypass pipeline is added to the system, so that oily gas can be discharged through the bypass pipeline at the moment of fuel injection, thus effectively protecting the filter bag.