When the sulfur burns, the flame will show a special and beautiful light blue color, but it will also release the poisonous and irritating gas sulfur dioxide when it burns, so we really have to guard against this dangerous beauty. Since the minimum ignition energy of sulfur is only 15mJ and the maximum explosion pressure is 277Kpa, it is easy to cause fire and explosion accidents. Among the many causes of sulfur fire, due to the insulation of sulfur powder, the “static electricity” generated during the production process Become the number one villain who does my part.
After reviewing the data, it is known that the types of electrostatic discharge that can ignite flammable powders are: corona discharge, spark discharge, brush discharge, and propagating brush discharge. These forms of electrostatic discharge events have higher duration and damage. For industrial production, electrostatic discharge can achieve rapid on-site ignition. In the early years, sulfur powder explosion accidents occurred almost every month, causing personal injuries and equipment damage. Therefore, it is necessary to pay attention to explosion and combustion prevention work. Specifically, how “static electricity” is generated and disrupted, and how people should prevent it can be roughly divided into three parts: production, transportation, and packaging.
In the process of producing sulfur powder, most of the factories adopt mechanical crushing method. First, block sulfur is crushed into powder, and then sent to cyclone separation equipment by wind for classification, so as to meet the requirements of different factories for powder particle size. Since the production process always involves rotation, collision, extrusion, friction, etc., sulfur powder will be charged with considerable static electricity, and the high insulation of sulfur powder makes it difficult for these charges to escape. In actual production, a large amount of electrostatically charged sulfur powder has accumulated in the collection system, which generates a strong electrostatic field in the dust collector, which can easily generate static sparks, ignite the sulfur powder, and cause dust explosion accidents. In addition, the agglomeration of sulfur powder caused by static electricity will cause the blockage of the feeding equipment, further increasing the risk of explosion.
The transportation process of sulfur is also a section with high incidence of static electricity – when the powder is rubbed in the pipeline, it will be electrified due to the contact between the powder, the pipeline and the dust collector during the airflow transportation of the sulfur powder. There are many factors that affect the generation of static electricity in sulfur powder during this process, as follows:
①Pipeline material: The powder is electrified, which is actually charged by contact separation. According to the distribution of static electricity, if the material of the pipeline and the sulfur powder are the same, it is not easy to generate static electricity. At present, most of the pipelines are transported by iron pipelines, which will inevitably affect the static electricity of sulfur powder.
②Pipeline length: When the powder is conveyed, the longer the distance, the more friction and collision between the powder and the pipe wall, and the greater the static electricity carried by the powder. When a certain distance is reached, the amount of static electricity carried by the powder is equivalent to the amount of static electricity leaked, and the saturated static electricity will be reached.
③Curve change: The smaller the curvature of the pipe, the greater the amount of static electricity generated by the powder. The curved pipe is more likely to generate static electricity than the straight pipe. The more bends in the curved pipe, the greater the static electricity.
④ Concentration of sulfur powder during transportation: The amount of static electricity generated by powder transportation at a certain concentration is certain, and changes in concentration will increase the number of friction and collisions between powders.
⑤Moisture content: An appropriate increase in moisture content is beneficial to the neutralization and leakage of static electricity generated by the powder, and at the same time, an appropriate moisture content can also increase the minimum ignition energy of the powder.
⑥ Gradient aperture: When the diameter of the powder conveying pipe changes from small to large and the wind speed decreases, the friction and collision between the powder and the pipe wall will decrease accordingly, and the amount of static electricity generated by the movement of the powder will also decrease, and vice versa. increase.
Therefore, if you want to reduce the electrostatic hazard during powder transportation, you should make corresponding adjustments to the above variable parameters. For example, when choosing the length of the pipeline, you should consider the length reasonably; try to reduce the number of elbows in the powder transportation pipeline and increase the diameter of the delivery pipeline; appropriately increase the moisture content of the sulfur powder, but it should not be too high so as not to affect the collection and treatment of the sulfur powder.
During the process of collecting sulfur, the negative charge generated by the sulfur will be carried into the storage silo along with the material, and high-voltage static electricity will accumulate in the silo. Then in the next step of packaging, when the sulfur material is automatically discharged, weighed, and bagged, it will continuously contact, rub and separate from the metal weighing scale and the woven bag (consistent with the electric double layer theory), so the sulfur material will A higher electrostatic charge is generated and accumulated again, and finally a large amount of electrostatic charge accumulates on the surface of the bag carrying sulfur. Although there is a certain attenuation between the charge on the surface of the material bag and the space atmosphere, due to the good insulation of the woven bag and sulfur, a high electrostatic voltage accumulates on the surface of the sulfur material packaging bag for a long time, and there is a Electrostatic spark discharge hazard.
As a chemical industrial raw material, sulfur powder has a large number of applications in explosives, steel pickling, pharmaceutical and food industry, pesticides, pigments, papermaking, catalysts and other fields, so its production scale is also very considerable, and its production safety checks become more important.