What is an explosion-proof dust collector?

First, what is explosion-proof dust collector?

An explosion-proof dust collector is a type of dust removal equipment specially designed for use in explosive environments, where its main role is to control dust generated during industrial production and to clean the production site. Explosion-proof dust collector is able to prevent industrial dust explosion caused by injury, the dust explosion caused by the impact of control within a manageable range. Usually the sense of the explosion-proof dust collector is to play a role in the dust explosion, there are some things to play a role in the dust explosion before, that is, to detect the dust will be exploded before a few microseconds, the dust collector will be quickly reinforced or will be extinguished sparks, this is called explosion-proof dust collector. Explosion-proof dust collector in the structure, function and operation are different from the conventional dust removal function, it uses a variety of explosion-proof design and safety measures to ensure that in a potentially explosive environment can be safe and effective operation. For example, the use of explosion-proof motors, explosion-proof electrical appliances, and explosion-proof valves can effectively prevent dust and harmful gases from entering into the electrical load, thus preventing the risk of explosion. Equipped with highly efficient filter materials and filter technology.

Second, explosion-proof dust collector design principle

　　Explosion protection is designed to extinguish combustible explosions at the initial stage and to prevent them from occurring. Once the explosion occurs, the pressure relief device in the dust collector can also be effectively dealt with. In the design process of the pressure relief device, the explosion relief pressure should be set for the dust collector baghouse design pressure of half, that is, 5-7.5KPa can be, when the pressure value reaches 10KPa, the staff need to open the pressure relief device for pressure release.

　　The side of the dust collector should be designed with a certain angle of inclination, the purpose of this design is to prevent the entry of air, in the process of the device for pressure relief, due to the existence of a certain angle of inclination of the side, so that the device can rely on its own gravity to carry out automatic reset. In addition, in order to enable the dust collector to quickly relieve the pressure, the design process should also reserve a large enough space, careful consideration of the location of the pressure relief port, such as: using the pipeline to connect the exhaust port and the outdoor safety relief device.

　　(ii) Explosion relief devices

　　The purpose of the design of the explosion relief device is to ensure the safe production of the system, the device mainly includes explosion-proof safety valves, explosion-proof diaphragms, heavy-duty safety valves and shrapnel-type explosion relief devices. In addition, it is also necessary to set up platforms and railings under the pressure relief device, in which the platform can only be used in the maintenance, so the staff can use the chain to stop the platform in normal times, and set up warning signs to prohibit the staff from passing freely.

　　(iii) Determination of wind volume, wind pressure and wind speed

　　Dust collector air intake device is composed of the lower duct, air volume adjustment valve and rectangular air intake pipe, in the process of designing the air intake pipe, the design needs to take into account the degree of negative pressure resistance of the wall plate of the duct, the air volume adjustment valve can be used as a factory through the piece, usually, the valve plate thickness of the dust explosion-proof device is controlled at about 5mm, the main wind speed should be able to effectively reduce the concentration of dust in the pipeline to avoid the cumulative, the main wind speed should not be less than 20m/s for wood dust, magnesium and aluminum dust. Generally speaking, for wood dust, the main wind speed is not less than 20m/s, magnesium and aluminum dust, the main wind speed is not less than 23m/s. The wind speed of the air cover should be based on the specific material and mode of operation.

(iv) Introduction of inerting devices

　　When inert gases are used as media in dust collectors, the control of the oxygen content inside the dust collector should be strengthened. The flow rate of the centralized dust collector system filled with powder should not be greater than 50% of the lower explosive limit. After the inerting device is added to the dust collector, an explosion-proof device with monitoring function should be added, so that an alarm can be issued automatically in case of abnormal operation.

(v) Automation design and detection of alarm interlocking functions

　　Automation design and detection alarm chain function is an indispensable function in the dust explosion-proof system, when the system finds that there is a potential danger in the vicinity, the function will be through the central control system to send the alarm information to the mobile disconnect, and to prevent the dust explosion phenomenon occurs.

Third. Precautions for dust collectors in flammable and explosive places

Dust collector in the use of the process, a lot of dust with flammable and explosive properties, in addition to the production enterprise workshop to improve fire and explosion-proof measures, but also need to dust collector special treatment to increase the dust collector’s explosion-proof ability, in order to ensure that the normal operation of the dust collector, to ensure the safety of production.

Containing a large number of CO and H2 dust flammable and explosive we all know very well, in addition to these, all can burn the material produced by most of the dust is flammable and explosive dust, such as: flour, coal dust, wood chips, cotton spinning staple fibers, and so on, and even the individual metal powder is also easy to explode under specific conditions, such as aluminum powder.
In the process of dust removal of these flammable and explosive dusts, it is necessary to achieve reliable airtightness of the dust removal equipment to prevent inhalation of air or leakage of gas, in order to ensure safe operation of the system in a stable environment.
In addition, the dust collector itself should also follow certain principles in design to realize its own explosion-proof, the main safety measures are as follows:

Explosion-proof measures for dust collector safety
Structure of dust collector: Bag dust collector used to deal with combustible gases is usually designed in round shape to increase the smoothness of dust flow and avoid excessive accumulation of dust.
2、Dust catcher adopts fire and explosion-proof dust bag, and increase the pressure relief device.
3、Dust catcher should ensure continuous dust removal to avoid dust deposition.
Safety valves for dust removal equipment piping
Avoid dead ends in the flue gas piping as much as possible to ensure that the piping is smooth; and increase the gas flow rate to prevent gas stagnation.

2, in front of the fan pipeline to set up a safety valve so that in the unlikely event of a gas explosion can be emergency pressure relief. The upper safety valve is often located at the top of the flue. Normal production pressure cover buckle down to the water seal to keep sealed, the height of the water seal is 250mm; in case of intense combustion in the flue, the pressure is greater than the weight of the cover, that is, the emergency open the cover, for pressure relief. The lower safety valve is located in front of the machine. During normal production, the gland closes the pressure relief hole under the action of a heavy hammer. The pressure relief hole is welded with a thin copper plate, in case of an explosion, the gas breaks through the copper plate, opens the gland and relieves the pressure.

Fourth, what are the explosion control measures in the dust removal system?

Dust removal equipment in the daily operation of the process, will encounter some security problems, especially wood factories and other places where there is flammable and explosive dust, so the dust removal system needs to be configured with explosion-proof explosion-control equipment, dust removal system explosion-control measures are mainly:

1, according to the nature of the dust gas filter bag material selection, in dealing with dust gas, if encountered is a high temperature gas, should be used to high temperature resistance, corrosion resistance, low flammability of the dust filter bag. If you encounter flammable and explosive dust, choose the material of the filter bag, you should choose high temperature resistance, not easy to burn the material.

2, in the case of combustion or sparks spattering, you can set up a combustion chamber or sparks spread collector in front of the dust collector, the incomplete combustion of dust and gas completely burned.

3, the use of dust collector dust, should be installed on the dust collector explosion-proof motor equipment, handling flammable gases must be installed alarm equipment.

4, in the dust removal system necessary to set up explosion-proof pressure relief port, so as to avoid excessive pressure explosion, installed in the outdoor to do a good job of lightning protection measures, the installation of lightning rods.

5, to avoid the airflow of debris impact impeller and casing sparks, so the fan needs to be installed in the back of the dust removal equipment.

6, pay attention to the health and cleanliness of the workshop, to avoid spontaneous combustion or explosion of dust due to the accumulation of dust inside the workshop dust and dust collector.

Fifth, how to improve the explosion-proof capability of dust removal equipment?

Many dusts have flammable and explosive properties, so to increase the explosion-proof capability of dust removal equipment, mainly from the following aspects:

1. During the dust removal process, the dust removal equipment should be reliably airtight to prevent air inhalation or gas leakage, so as to ensure the safe operation of the system in a stable environment.

2, the structure of the dust removal equipment, used to deal with combustible gases bag filter is recommended to be designed into a round type, increase the degree of smoothness of the dust flow, to avoid excessive accumulation of dust.

3、Adopt fire and explosion-proof dust bag and increase pressure relief device.

4, to ensure continuous dust removal to avoid dust deposition.

5, the flue gas pipeline to avoid dead ends, to ensure that the pipeline is smooth; and to mention the speed of gas flow, in order to prevent the occurrence of gas stagnation phenomenon. Set up a safety valve in the pipeline before the fan, so that in case of an explosion can be emergency pressure relief, the upper safety valve is often located in the top of the flue, the lower safety valve is located in front of the machine.