With the rapid development of industrial manufacturing, dust and powder which mostly are combustible and explosive are inevitably generated during processing in all walks of life, such as the lithium battery industry, 3D printing industry, laser industry, food industry, woodworking industry, and so on. In recent years, the combustion and explosion accidents caused by combustible dust have occurred very frequently, leading to fatal accidents and property losses, and have attracted extensive attention from the public.
The explosion caused by dust is an oxidation reaction which is completed instantaneously under specific conditions when the suspended dust particles are in full contact with the oxygen in the air. This results in generating a tremendous amount of heat and subsequently raising the temperature and pressure. Generally, any explosion caused by dust must follow five conditions: an ignition source, fine combustible dust, dust suspended in the air, and reaching the limit of explosion concentration, confined space, and oxygen.
With the strengthening of environmental and health awareness, a dust collection system has been widely applied in all industries involving powdery materials. The dust collection system acquires the purpose of a pollution-free environment by utilizing the suction energy provided by the fan to collect the dust using the suction hood, and sending the airflow containing dust into the dust collector through a ventilation pipe for purification.
In a relatively closed dust collection system, the dust concentration is often high enough to reach the lower explosion limit of dust, which provides a prerequisite for a dust explosion. According to statistics, most explosion accidents occur in the dust collection system, so the industrial dust collector is the most dangerous part of the dust collection system.
We can take the following explosion-proof measures for the dust collection system to prevent from explosion according to the above five conditions.
1. Ignition source
The common ignition sources in the dust collection system include mechanical friction and collision, spontaneous combustion under the accumulated temperature of the dust, and electrostatic discharge. For the explosion caused by mechanical friction and collision, spark detection and extinguishing device can be installed in the pipeline. Installing a temperature monitor in the industrial dust collector and linking it with the fire extinguishing device is a good way to avoid spontaneous combustion of dust due to accumulated temperature. As for electrostatic discharge, we can connect the filter with the host, and the industrial dust collector can be grounded.
2. The concentration of Combustible Dust
The concentration of combustible dust can be reduced by adding inert dust into the industrial dust collector to mix with the combustible dust.
For some industries (such as 3D printing), aluminum, magnesium, and other dust used by the printers are easily oxidized in the air. The effective way to prevent oxidation is by connecting the 3D printer with the industrial dust collector to form a closed environment and extracting air by filling with inert dust.
In spite of taking the above measures, the explosion caused by dust cannot be completely eliminated. In such case, other equipment, such as explosion isolation valves and flameless quench device, is needed to reduce the damage caused by the explosion.
As a matter of fact, there are numerous companies engaged in industrial dust collection systems available on the market, such as Villo Vacuum. Mastering technologies in dust collection, Villo Vacuum has developed a professional explosion-proof dust collection system with the functions of temperature monitoring, pressure monitoring, explosion relief, and explosion-proof. The industrial dust collector has strong pressure resistance, meets the design standards of pressure vessels, and can efficiently and safely remove the dust in the workshop.
Huile Insford Research Institute, a subsidiary of Villo Vacuum, has established an explosion-proof experimental base to mainly engage in the protection of industrial explosion (including explosion-proof system and equipment) and environment (including Villo dust collection system and industrial dust collectors), etc.