The composition and working principle of the bag filter

The bag dust collector structure consists of: dust collector ash hopper, inlet and outlet air duct, filter chamber (middle and lower tank), clean room, filter bag and frame (bag cage), manual air inlet valve, pneumatic butterfly valve, pulse Cleaning agencies, etc.

Working principle of bag filter: Bag filter is a filter type dust removal device based on the filtration principle. The dust in the gas is filtered out by using organic fiber or inorganic fiber filter cloth.

Dust removal process: The dust-containing gas enters the middle tank from the air inlet and enters the bag from the outside of the filter bag. The dust is blocked on the surface outside the filter bag. The purified air enters the bag, and then enters the upper box from the upper part of the bag. Finally, It is discharged by the exhaust pipe.

First, the working principle of the bag filter

After the dust-containing gas enters from the upper air inlet of the ash bucket, under the action of the windshield, the airflow flows upward, the flow velocity decreases, and some large-particle dust is separated and falls into the ash bucket due to the inertia force. The dust-containing gas enters the middle tank and is filtered and purified by the filter bag. The dust is retained on the outer surface of the filter bag, and the purified gas enters the upper tank through the filter bag mouth, and is discharged from the air outlet. As the dust on the surface of the filter bag increases, the pressure difference between the inlet and outlet of the dust collector increases. When the precipitator resistance reaches the set value, the control system issues a clearing command and the cleaning system starts to work. After opening the solenoid valve connected to the first signal immediately, a small patch of the compressed air is discharged upper chamber, since both ends of the diaphragm by a small change in the force, so that a small diaphragm is closed exhaust passage opening, upper large membrane The compressed air of the air chamber is discharged from the passage, and the force is changed at both ends of the large diaphragm to make the large diaphragm move, and the closed output port is opened, and the compressed air in the air bag is sprayed into the bag through the output pipe and the blowing pipe, thereby realizing Clean up. When the control signal stops, the solenoid valve closes, the small diaphragm and the large diaphragm are successively reset, and the injection stops. The pulse valve is a key component of the pulse bag type dust collector, and its service life is the most concerned issue for users. The company can provide imported filter bags and pulse valves according to the needs of users.

Second, the comparison of the cleaning of the bag filter

The cleaning method is an important factor in determining the performance of the bag filter. The bag type dust collectors are classified by means of cleaning, and the basic types are: mechanical vibrating cleaning method, back blowing cleaning method, back blowing, vibrating combined cleaning method, pulsating back blowing cleaning method, pulse blowing cleaning Gray way. The low-pressure pulse bag type dust collector belongs to the pulse jet cleaning method.

Third, the bag filter technology features

(1) The submerged pulse valve is used to open and close quickly, and its own resistance is small. For a filter bag of 6 m to 8 m long, the injection pressure is only 0.15 to 0.3 MPa, and a good cleaning effect can be obtained.

(2) Strong cleaning ability. When the dust is removed, the acceleration of the surface of the filter bag is far greater than that of other types of bag filters, and the cleaning is uniform and the effect is good.

(3) High filtration load. Due to the strong dust protection, even if the dust collector is operated at a higher filtering wind speed, the resistance will not be too high, generally 1200 ~ 1500Pa, compared with the anti-air dust collector, the same filtration area, pulse bag type dust removal The device has a larger processing volume.

(4) It is convenient to check and replace the filter bag. The filter bag is easy to install and change bags without tying. The operator does not need to enter the inside of the cabinet, and the operating environment is good.

(5) Equipment cost is low. Due to the high filtration load, the required filtering area for processing the same amount of flue gas is smaller than that of the reverse blow bag type dust collector, so the equipment is compact and the floor space is small.

(6) Advanced control technology. The control system with PLC programmable controller as the host controls the operating parameters such as dust collector cleaning, inlet flue gas temperature and cleaning pressure, and has complete functions, stable and reliable.

Fourth, technical performance

The technical performance of the low-pressure pulse bag type dust collector is mainly reflected in the treatment of air volume, dust concentration of the outlet, equipment resistance and the service life of the filter bag.

(1) Handling air volume

The low-pressure pulse bag type dust collector can process dust with a large air volume to reduce the filtration area, miniaturize the equipment and save investment. In the case of meeting the dust-removing object, the appropriate filtering wind speed can be determined according to the cleaning method, the dust property, the filter bag material, and the like.

(2) Export dust concentration

The low-pressure pulse bag type dust collector has high dust removal efficiency, and the dust concentration at the outlet can fully meet the national emission standards, and can even reach 10mg/m 3 or less.

(3) Equipment resistance

The resistance ΔP of the precipitator is proportional to the power of the fan. This is an indicator directly related to the energy consumption of the fan and relates to the operating cost of the dedusting system. The resistance of the dust collector is related to the structure of the device, the type of filter material, the nature of the dust, the method of cleaning, the speed of filtration, the temperature of the gas, and the humidity.

The low pressure pulse bag filter controls the dust collector resistance to within the range of 1200 to 1500 Pa. Ensure that the deposited dust is quickly and evenly removed from the filter cloth without damaging the filter bag and consuming less power.

The dust collector resistance consists of three parts: ΔP = ΔP 1 + ΔP 2 + ΔP 3

Where: ΔP 1 - mechanical resistance

ΔP 2 —— resistance of filter cloth

ΔP 3 - resistance of the dust layer

(4) The service life of the filter bag

The life of the filter bag is related to factors such as material, flue gas temperature, composition, acid dew point, dust properties, etc., and is also affected by filtration wind speed, inlet dust concentration, cleaning frequency and management and maintenance. Therefore, for a dust removal device, the important parameters such as the filtering wind speed and the material of the filter bag and the cleaning method are correctly selected to ensure the service life of the filter bag.