Coal dust explosion problem

This post was last edited by sdwfsgyykai on 2019-6-28 07:44. Dust cannot be humidified, and it won’t explode; grounding serves only as a psychological comfort. Coal dust has poor electrical conductivity, but overall there are no problems

This post was last edited by shuker666 on 2019-6-28 at 10:51. Three key elements: 1. Fuel (coal powder)； 2. Oxidizing agent (air or oxidizer) ； 3. Heat sources (open flames, vibration, friction, etc.) ； An explosion can occur as long as all three elements are present + the mixture is within its explosive limit ； A dust explosion occurs when combustible dust, within its explosive range, comes into contact with a heat source (such as an open flame or high temperature) ； Rule: (1) The smaller the dust particle size, the lower the lower explosion limit ； (2) The higher the oxygen concentration, the lower the lower explosion limit ； (3) The higher the content of combustible volatiles, the lower the lower limit for dust explosion. Therefore, it is necessary to eliminate these three elements (which are unavoidable for this project), and it is essential to ensure that the area is no longer within the explosive limit of dust before burning can take place ； Refer to the design code--GB50058.

Thank you to all colleagues for your participation. I think it’s sufficient to install cut-off valves, 8-shaped blind flanges, and rupture disks on the pipeline between the hot air furnace and the crusher; as long as positive pressure is maintained, dust explosions will not occur. Not much has been done in this area; I’m not sure if my understanding is correct, so please give me some guidance. Another question: Could an explosion occur at the moment dust is ejected from the hot air furnace?

This post was last edited by lcmqh@163.com on 2019-6-30 at 17:22. Your approach carries significant risks; when coal powder is mixed with oxygen-rich air and the concentration and temperature are appropriate, even a small ignition source can easily lead to deflagration or explosion. In the pipes between the crusher and the hot air furnace, flame arresters cannot be installed due to the transportation of dust-laden gas, and accidents are likely to occur in case of backflow； It can be set up in such a way that the dust can be collected using dust removal devices and then transported to a combustion furnace, where it is injected into a hot air furnace using a high-pressure fan for combustion; this approach is safer.

Thank you. Add a cyclone and a bag filter to collect it, then spray. On the one hand, I’m worried about tempering. I’m more afraid of an explosion at the exhaust outlet, which could destroy the hot air furnace.

Design begins with safety considerations in mind, with the goal of achieving intrinsic safety; otherwise, it fails to meet safety standards and design principles, and safety inspections are out of the question – no one would dare to sign off on such a design. Both safety and environmental protection are aspects that can only be improved through investment after the design is completed, not just through theoretical discussions.

Thank you. I’ve seen ones that are useful, but their capacity is small. Moreover, **controls are very strict these days; the purpose of posting this is to ask everyone for legitimate and compliant ideas and approaches. Safety is no trivial matter.

Coal powder can ignite and explode in the pipelines, so when the pipelines are in operation, it is advisable to first pass some non-flammable material such as limestone powder through them to prevent accumulation inside the pipes. Then, explosion-proof valves are installed in locations where explosions are more likely to occur.

There is a book on dust explosions or NFPA standards; at least check 68/69/499/652/654. There are also the standards for those various zones: AQ3009, AQ4273, GB15577, GBT15065, and 12476. There’s a lot of information available, and everything mentioned above is correct, but it’s not comprehensive. Dust explosions are not given as much attention as flammable liquids, and they are easily overlooked, yet the risks are very high