Author: Weng Zhenke and Zhang Xuening

[Abstract] Based on the analysis of the reasons for the frequent failure of explosion-proof electrical equipment, the prevention methods and countermeasures of the failure of electrical equipment are explored, which provides reference for reducing the risk coefficient of the failure of petrochemical explosion-proof electrical equipment and ensuring safe production.

【 Key word 】 explosion-proof; Electrical equipment; Misfired; Safe production

[CLC Number] TD684

[Document identification Code] B

[Article number] 1003-3467 (2010) 08-0066-01

With the rapid development of science and technology, the scale of industrial production is expanding day by day, and the problem of fire prevention and explosion protection is more important. Electrical equipment in the petrochemical industry may occur in normal use or failure, electric spark, arc, high temperature, static electricity, friction, impact sparks, etc., resulting in fire and explosion accidents. According to the relevant figures, from the point of view of the direct cause, electrical caused the most, accounting for 30.3% of the total; This was followed by careless use of fire, accounting for 22.9%, and careless production operations accounting for 5.4%. Among them, the proportion of electrical fires has increased for three consecutive years, from 21.9% in 2005 to 28.3% in 2007, and the proportion of electrical fires will continue to rise. Therefore, how to prevent the failure of electrical equipment and reduce the failure and failure rate of equipment in the petroleum and chemical industry is of great significance to ensure the safe production of the petrochemical industry and realize the coordinated and sustainable development of safety and production, safety and efficiency.

1 Reasons for the failure of explosion-proof electrical equipment

1.1 Product quality of electrical facilities Product quality directly determines the explosion resistance and explosion proof effect of electrical equipment. As we all know, petrochemical production with flammable and explosive, high temperature and high pressure, open air and continuous production characteristics, due to its large investment, large scale, large social impact, belong to the risk industry, it requires the use of electrical equipment in the production site must be explosion-proof performance of various technologies are in line with the national standards of electrical equipment, in order to achieve the real explosion-proof purpose. Although China has developed new explosion-proof products related standards, but driven by commercial interests, some enterprises ignore national property and people's life safety, jerry-building, shoddy manufacturing. In some areas, fake and shoddy and unlicensed (no production license, no explosion-proof certificate) products flooded the market. Such as: explosion-proof motor winding quality reliability is not high, noise and vibration quality is poor; The quality of explosion-proof refueling machine varies; The structure of explosion-proof lamps is not qualified.

1.2 The installation of electrical equipment is not installed in accordance with the requirements or unqualified installation is one of the main reasons for the failure of electrical equipment. The connecting parts on the explosion-proof electrical equipment (such as junction boxes, junction boxes) are basically fixed with screws, and the explosion-proof surface is likely to be damaged in the process of picking up; If special tools are not selected, hard disassembly and hard knocking will deform and distort the equipment shell, resulting in shorter explosion-proof clearance and larger width; Residual wood chips and welding slag on the explosion-proof surface make the gap widen or damage and fail to explode; A seal with an inner diameter that is too large or too small will also make the horn lose its explosion-proof ability. All the above non-standard operations are very easy to cause equipment failure. In addition, due to the lack of explosion-proof knowledge of equipment installation personnel, non-standard production operations, and weak explosion-proof safety, it is also the main reason for the failure of equipment.

1.3 Environment and Equipment Purchase explosion-proof is the foundation of safe operation in mines. The quality of the purchased equipment will directly affect the installation quality and explosion-proof safety technology level. In general, even if the shoddy equipment is not used for a long time, it is very prone to electric spark igniting flammable materials, resulting in electrical fire or explosion; Or the electrical parts of the equipment are unqualified, or the electrical insulation part is damaged, resulting in overload and the equipment fails to explode. In addition, due to the flammable and explosive characteristics of the petrochemical production environment, improper installation of explosion-proof equipment is equal to design, manufacturing and construction will also cause failure.

1.4 Maintenance and Management of electrical equipment The explosion-proof management of petroleum and chemical electrical equipment is an important part of safety management. However, "heavy use, light maintenance" is a common problem in petrochemical enterprises, such as perennial disrepair of equipment, conductor support insulation damage or wrapped insulation material falling off or damaged; Some electrical equipment that has been running for many years generally has the problem of serious aging; Corrosion of flameproof surface is common. Line connection Wire connector connection is not secure, movable contact (switch. Fuse, contactor, socket, bulb and lamp holder) poor contact, etc. All these problems will seriously endanger the safety of petrochemical production personnel and national property.

2 Measures to prevent the failure of electrical equipment

2.1 Correct use of explosion-proof equipment Correct selection and procurement is the basic guarantee of electrical explosion-proof safety. When setting up electrical equipment in explosive danger places, explosion-proof electrical equipment that conforms to national standards and is suitable for the dangerous area should be selected, and the explosion-proof certificate of professional organizations, inspection reports of explosion-proof electrical products and related technical documents should be reviewed. The selection of chemical explosion-proof equipment, the characteristics of flammable and explosive substances in the environment, the principle type and effect of explosion-proof, the applicability of the environment, the particularity of installation, maintenance and use, and even economic benefits are all factors to be considered. However, for safety considerations, the most critical and core considerations are the characteristics of flammable and explosive materials and the type and effect of explosion-proof principles.

2.2 Put an end to the unqualified operation of explosion-proof electrical equipment Due to the low quality of some frontline workers in the petrochemical industry, the safety awareness is not strong, coupled with the widespread flammable and explosive risk in production sites and the characteristics of high temperature and high pressure production process, there is widespread misoperation or illegal operation phenomenon. Even if the performance and quality of explosion-proof electrical products, if used improperly, not only can not play the role of explosion-proof, and may even lead to the failure of electrical equipment, become the culprit of crisis safety. Therefore, it is necessary to strengthen safety training, improve workers' awareness of safe operation and technical level, reduce the failure rate of electrical equipment, and ensure that electrical equipment fails.

2.3 Strengthen the maintenance and maintenance of explosion-proof electrical equipment If the installation and maintenance is improper, it will also lead to the failure of the explosion-proof mechanism, so that the explosion-proof electrical equipment will lose the explosion-proof ability. Therefore, in the installation and maintenance of explosion-proof electrical equipment, the following points must be done:

(1) The cross-sectional area of the wire or cable selected in the explosive danger place must meet the requirements, and the laying of the cable must meet the explosion-proof requirements, otherwise any operation that does not meet the requirements will cause the entire system to lose the explosion-proof performance.

(2) The flameproof joint surface of flameproof electrical equipment should be free of trachoma, mechanical scars and rust. This point should be paid special attention to when maintenance, it is strictly prohibited to paint the flameproof joint surface.

(3) After maintenance, it is necessary to ensure that the shaft and shaft hole of the flameproof motor and the fan, and the fan and the end cover are in normal working condition, and there is no friction.

(4) Except for intrinsically safe electrical equipment, all equipment should have a warning sign and technical operation instructions after power failure.

(5) Electrical circuit explosion-proof electrical equipment must meet the relevant requirements.

2.4 Ensure Safe power supply Safe power supply is an important link to reduce electrical equipment failures and ensure the safety of petrochemical production. The voltage, current, temperature and other parameters in the operation of electrical equipment should not exceed the rated allowable value. Pay special attention to the heat of the connector of the line or the inlet and outlet of the electrical equipment. In the environment with gas or steam explosive mixture, the surface temperature and temperature rise of the electrical equipment shall meet the specified requirements; In an environment with dust or explosive mixtures of fibers, the surface temperature of electrical equipment should generally not exceed 125 ° C. Electrical equipment should be kept clean to prevent accumulated dirt and dust from causing fire hazards.

3 Closing remarks

Electric explosion-proof in petrochemical industry is directly related to the safety of production and operation management. On the basis of the several explosion-proof countermeasures and suggestions mentioned above, the technical training of the petrochemical staff should also be strengthened, the habit of consciously obeying the safety regulations and correct operation should be formed, and the safety knowledge and skills of the work content should be mastered, so as to effectively do the electrical safety management of petrochemical production and ensure the safety and efficiency of petrochemical production.

References:

[1] Gong Zhenwen. Discussion on the cause and prevention of failure of explosion-proof electrical equipment. Hydraulic Coal Mining and pipeline Transportation,2009,3

[2] Xu Gang. On the selection and safety application of explosion-proof electrical equipment. Safety and Standards, 2009,29 (1)