Dust explosion prevention in coal chemical industry

Safety Regulations for Dust Explosion Prevention GB 15577-1995 1. Subject Matter and Scope of Application These standards specify the safety requirements for preventing dust explosions in industrial areas prone to such explosions. 　　This standard applies to the engineering design, management, production, storage, and transportation of areas at risk of dust explosions. 　　This standard does not apply to underground mines and **factories. 　　 　　2 Referenced Standards GBl1651 Rules for the Selection of Personal Protective Equipment GB/T15605 Guidelines for Pressure Relief in Dust Explosions 3 Terms 3.1 Combustible dust Dust that can undergo a vigorous oxidation reaction with gaseous oxidizers or air under certain conditions. 　　3.2 Dust explosion hazardous areas Areas where combustible dusts and gaseous oxidizers (or air) are present. 　　3.3 Inerting Fill areas at risk of dust explosions with sufficient inert gas, or spread inert dust on top of the dust layer. Methods to render these dust mixtures non-explosive. 　　3.4 Explosion suppression: A technology for controlling explosions that involves using physicochemical processes to extinguish the flames, thereby preventing unexploded dust from participating in the explosion. 　　3.5 Explosion venting: In the event of an explosion within an enclosure containing dust and gaseous oxidizers or air, before the explosion pressure reaches the limit strength of the enclosure, the high-temperature, high-pressure combustion products and unburned materials generated by the explosion are allowed to escape in a safe direction through weak points in the enclosure. Explosive control technology to prevent the enclosure from being damaged. 　　3.6 Secondary explosions When a dust explosion occurs, the shock wave from the initial explosion lifts the accumulated dust again, forming a dust cloud that is then ignited by the subsequent flames, resulting in successive explosions. 　　 　　4 General Provisions 4.1 Enterprises constructing, renovating, or expanding in areas at risk of dust explosions must comply with the provisions of this standard. Existing enterprises that do not meet the requirements of this standard must formulate a plan for safety technical measures to achieve compliance within a specified time frame. 　　4.2 Corporate legal persons must be aware of whether there are any areas in their enterprises prone to dust explosions, and must take measures that can effectively control such explosions. 　　4.3 Enterprises should, in light of the characteristics of their own dust explosion-hazardous areas, formulate detailed implementation rules for dust explosion prevention as well as safety inspection checklists, and conduct thorough dust explosion prevention inspections using these checklists. Enterprises should conduct inspections at least once per quarter, while workshops (or production units) should conduct inspections at least once per month. 　　4.4 Enterprises should earnestly carry out education on safe production and dust explosion prevention, popularize knowledge regarding dust explosion prevention and safety regulations, so that employees are aware of the degree of risk in areas prone to dust explosions within their enterprises as well as the measures taken to prevent such explosions ； Employees must receive technical and operational training and pass relevant examinations before they are allowed to take up their posts. 　　4.5 Open flames and smoking are strictly prohibited in areas at risk of dust explosions, and the electrical equipment used must be dust-proof. 　　4.6 To produce dust-explosion-proof products, permission must be obtained from the Ministry of Labor or an entity designated by it, and a license must be issued. 　　4.7 Facilities for safety, ventilation, explosion prevention, and explosion relief shall not be removed without the approval of the competent authorities. 　　4.8 The safety assessment of construction projects should include an analysis of the risk of dust explosions and explosion prevention measures. 　　 　　5 Prevention of ignition of dust clouds and dust layers 5.1 Prevention of spontaneous combustion of bulk powders 5.1.1 Hot powders that are prone to spontaneous combustion must be cooled to normal storage temperatures before storage. Powders that can catch fire spontaneously at room temperature (spontaneously combustible materials) should be stored in inert gases or liquids, or stored in other safe ways. 　　5.1.2 Under normal storage conditions, when large quantities of combustible bulk powders are stored, it is necessary to continuously monitor the temperature of the powder ； When an increase in temperature or gas evolution is detected, measures must be taken to cool the powder ； When the spontaneous combustion process has progressed to a point where it could lead to fire or explosion, careful measures must be taken to stop its progression. 　　5.2 Preventing ignition by open flames and hot surfaces 5.2.1 When performing operations with open flames in areas where dust explosions are a risk, the following regulations must be followed: a. An operation permit approved by a safety officer is required ； 　　b. Before starting any open-flame operation, combustible dusts in the area where such operations will take place must be completely removed ； 　　c. During open-flame operations and the subsequent cooling period, it is strictly prohibited for dust to enter the area where open-flame operations are carried out ； 　　d. The areas where open-flame operations are carried out must be separated or isolated from other areas of the equipment. 　　5.2.2 For equipment or devices in direct contact with dust clouds (such as light sources, heaters, etc.), the allowable surface temperature must be below the lowest ignition temperature of the corresponding dust layer. 　　5.2.3 Areas, equipment, and installations where flammable or explosive dusts are present shall comply with the following provisions: 5.2.3.1 The bearings of process equipment shall be provided with dust-proof seals ； If overheating is a possibility, detectors capable of continuously monitoring the bearing temperature must be installed. 　　5.2.3.2 Belt drives should not be used ； If a belt drive is used, a speed difference sensor and an automatic anti-slip protection device must be installed ； When sliding friction occurs, the protection device should ensure automatic shutdown. 　　5.2.3.3 Bucket elevators must be equipped with safety protection devices. 　　5.3 Prevention of arc and spark ignition 　5.3.1 In areas at risk of dust explosions, appropriate lightning protection measures should be taken. 　5.3.2 When there is a risk of ignition due to static electricity, the following rules must be followed: 　5.3.2.1 All metal equipment, device enclosures, metal pipes, supports, components, and parts should generally be directly grounded to prevent static electricity ； Where direct grounding is inconvenient or not permitted by the manufacturing process, indirect grounding can be achieved using conductive materials or products. The direct static ground resistance shall not exceed 100Ω, and the indirect ground resistance shall not exceed 107Ω. 　　5.3.2.2 Equipment directly used for holding powder, as well as pipes (conveyors) for transporting powder, etc., should be made of metal or anti-static materials. 　　5.3.2.3 All metal pipe connections (such as flanges) must be bonded. 　　5.3.2.4 Operators should take anti-static measures. 　　5.3.2.5 It is prohibited to use directly grounded metal conductors or screens in contact with rapidly flowing powder to eliminate static electricity. 　　5.4 Preventing ignition by frictional collisions and sparks 5.4.1 When dust clouds can be ignited by sparks generated from accidental collisions (such as those between metal debris and internal components of processing equipment), measures must be taken to prevent such collisions from occurring. 　　5.4.2 At the feed point of the process flow, magnets, pneumatic separators, or screens that can remove impurities mixed in the material should be installed to prevent these impurities from colliding with the equipment. 　　5.4.3 Sparks generated by the friction between aluminum, magnesium, zirconium, germanium, etc., or powders containing these metals, and stainless steel are particularly dangerous ignition sources. When there are powders of the aforementioned metals or alloys present, it is necessary to prevent the generation of friction sparks. 　　5.4.4 For process equipment containing dust that is particularly flammable, it is necessary to ensure that no frictional or impact sparks are generated in the areas where such dust is present during maintenance operations. 　　5.4.5 There are no protective measures equivalent to those for working with open flames; the use of rotary grinding wheels and rotary cutting discs for grinding and cutting is strictly prohibited. 　　5.5 Inerting 5.5.1 In process equipment used for the production or handling of powders that are highly flammable, it is necessary to inert the dust clouds using inert gases. 　　5.5.2 In equipment for processing or handling powders such as grinders and mixers, it is necessary to determine whether inert gas blanketing should be used, based on the dust explosion properties of those powders. 　　5.6 Strictly keeping the dust concentration below the range of dust explosion concentrations is an effective measure for explosion prevention. 　　Under special circumstances, such as in powder exhaust systems and chambers used for electrostatic powder spraying, it is necessary to keep the dust concentration above the upper limit of the dust explosion concentration. 　　 　　6 Reducing damage caused by initial explosions 6.1 Segmentation and isolation 6.1.1 The connections of process equipment must ensure that the various devices can be easily separated and moved without the need for open-flame operations. 　　6.1.2 When designing process equipment, technically feasible isolation must be considered to prevent the explosion of one piece of equipment from affecting adjacent equipment. 　　6.2 Protective shutdown during explosion 6.2.1 In emergency situations, it is necessary to be able to remotely cut off the power supply to all motors. 　　6.2.2 Depending on the size of the workshop, several switch panels for remote motor power supplies that can be used interchangeably can be installed. The switch must be properly marked, and self-luminous signals are preferable for marking. 　　6.2.3 Remote control switches must be installed in locations where they can still be operated in the event of a fire or explosion in the workshop. 　　6.3 Workshop 3 should be protected by an automatic explosion suppression system. 　　6.4 Controlling deflagration pressure 6.4.1 When producing and handling powders that can cause explosions, in the absence of an automatic explosion suppression system or pressure relief measures, all process equipment must be capable of withstanding the overpressure generated by internal explosions ； At the same time, the connection parts between various process equipment (such as pipes, flanges, etc.) should also have the same strength as the equipment itself ； An explosion suppression device must be installed at the connection point between high-intensity equipment and low-intensity equipment. 　　6.4.2 All dust discharge pipes and connection pipes between different process equipment shall be capable of withstanding the overpressure generated by internal dust explosions. 　　6.5 Explosion venting 6.5.1 When the strength of the process equipment is not sufficient to withstand the pressure generated by a fully developed internal dust explosion, explosion vents must be installed. The size of the explosion vent should be determined based on GB/T15605 or dust explosion standard tests and practical evaluations, to ensure that the maximum explosion venting pressure that may occur in the event of an accidental explosion does not exceed the maximum internal pressure that the container can withstand. 　　6.5.2 For process equipment equipped with internal piping, the recommended design criteria should generally be such that it can withstand an internal overpressure of at least 0.1 MPa. 　　 　　7 Prevention of secondary explosions 7.1 Preventing the escape of powder from production equipment 7.1.1 The joints, inspection doors, baffles, and explosion vent covers of process equipment must be tightly sealed to prevent powder from leaking into the workshop. 　　7.1.2 The pressure inside the process equipment when there is powder present should be lower than the ambient pressure outside the equipment. 　　7.2 Effective dust removal in special locations 7.2.1 In special locations where dust leakage cannot be completely prevented (such as at the points where powders enter and exit process equipment), effective safety measures for dust removal must be implemented. 　　7.2.2 Effective protective measures must be taken in areas where powder is handled manually. 　　7.2.3 The area where packaging is carried out must be cleaned regularly. 　　7.3 The packaged powdered products should be delivered to a separate storage room as soon as possible. 　　7.4 Perform regular cleaning tasks 　7.4.1 All production workshops and storage areas where dust may accumulate should be cleaned promptly. 　　7.4.2 The use of compressed air for purging is prohibited. 　　 　　8 Personal Protection and First Aid 8.1 Personal Protection 8.1.1 Production workers must use personal protective equipment in accordance with the relevant provisions of GBl1651. 　　8.1.2 In process flows where inert gases are used or in areas where toxic gases may be released, respiratory protection devices capable of purifying the air must be provided. 　　8.1.3 In the workplace, it is strictly prohibited for production workers to wear clothing made of synthetic fibers close to their skin. 　　8.2 Rescue 　8.2.1 Enterprises must prepare a rescue plan for dust explosion incidents and submit it to the competent authorities for approval. 　　8.2.2 Regular fire extinguishing and rescue training should be conducted for all employees, in close cooperation and under the guidance of the local fire department. 　　 　　9 Fire Extinguishing 9.1 The use of fire extinguishing methods that can stir up deposited powder to form dust clouds is prohibited. 　　9.2 When extinguishing fires, nozzles with good atomization performance must be used to ensure that the fire extinguishing agent can form a dust cloud and a liquid mist curtain. 　　9.3 The appropriate extinguishing agent should be selected based on the physicochemical properties of the dust. 　　9.4 If contact between the burning material and water produces explosive gases, the use of water to extinguish the fire is prohibited. 　　9.5 Fire-fighting equipment and extinguishing agents must be available at all times. 　　 　　10 Structure and Layout of Buildings and Structures 10.1 Buildings and structures equipped with process equipment at risk of dust explosions or containing explosive dust should be separated from one another, with sufficient safety distances maintained between them. 　　10.2 Buildings should preferably be single-story, with roofs that utilize lightweight structures; blast-resistant structures can also be used. 　　10.3 Structure of multi-story buildings 10.3.1 Frame structures are suitable for multi-story buildings ； In areas where such a structure cannot be used, blast vents of sufficient size must be installed in the walls. 　　10.3.2 If windows or other openings are used as blast vents, it is necessary to ensure that they can effectively discharge blast pressure in the event of an explosion. 　　10.4 Hazardous process equipment in the factory building should be located at a higher position within the building, near the exterior walls. 　　10.5 Equipment, beams, scaffolds, walls, etc. must have a surface structure that facilitates cleaning, and should not have upward-facing joining planes. 　　10.6 Evacuation Routes 　　10.6.1 The work area must have a sufficient number of evacuation routes. The number and location of evacuation routes are determined by the design department and approved by the competent authority. 　　10.6.2 Evacuation routes must be equipped with clear signage and emergency lighting. 　　10.7 Process equipment that is particularly dangerous should be installed in outdoor areas outside the building. --------------------------------------------------------------------------------

Workshops containing coal dust need to be equipped with explosion-proof measures, as well as anti-static measures. Including equipment handling, construction procedures, and operating safety regulations

Nitrogen is added to the system during coal powder preparation； Nitrogen or carbon dioxide is used to transport pulverized coal ； Blowout valves can protect equipment from damage in the event of an explosion.

Brother upstairs, if nitrogen is used for transportation, doesn’t that require a continuous supply of nitrogen? Is such a cost high?

Which equipment in gasification plants uses explosion-proof panels and other explosion-proof measures?

GB 15577-2007 Safety Regulations for Dust Explosion Prevention

Last edited by jensse on 2014-10-18 08:53: MT/T 714-1997 Technical Specifications for Explosion Protection in Coal Powder Production

Defensive measures are definitely necessary for coal chemical industry dust; a negative-pressure dust collection system must be used, and it is preferable that it be explosion-proof