Explosion proof and safety of the hottest low temp

2022-10-15
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Explosion proof and safety of low temperature air separation equipment

explosion proof and safety problems of low temperature air separation equipment involve many disciplines. The author has been engaged in the low-temperature air separation industry for about 40 years, and wants to sort out and summarize some information I have obtained about this problem by using the concepts and methods of total quality management, so as to achieve the purpose of throwing bricks and attracting jade. At the same time, it points out the specific problems, so that the explosion-proof safety measures of domestic air separation equipment are improving day by day, and the harm is reduced. Firstly, the following views are put forward: ⑴ the explosion of low-temperature air separation equipment is the micro explosion of oxygen and unsaturated hydrocarbons (CnHm) under spark ignition, which may lead to a big explosion. ⑵ here we only talk about the cryogenic equipment in the area where the explosion occurred during the evaporation of liquid oxygen. Not to mention the combustion and explosion of oxygen and other substances in high-temperature areas, such as the combustion and explosion of oxygen compressors, oxygen pipes, etc. penetrating the exposed print head from the paper outlet of the cover plate. (3) during the evaporation of liquid oxygen, dry evaporation is formed in a certain area, which makes hydrocarbons separate out in solid state and explode in the case of sparks. According to the upper host 1) peak power of power supply: ≤ 10 kW (including peripheral installation such as cooling and high temperature installation); From the point of view, the measures to prevent explosion are proposed as follows. 1. Measures to block the entry of hydrocarbons. As the saying goes, "disease comes from the mouth". Then, how to block the "disease" -- the pathways of hydrocarbons entering the liquid oxygen area, there are the following measures (see Table 1). Table 1 measures to block the entry of hydrocarbons (CnHm) note the reasonable selection of air intake. Choose an air inlet with the least hydrocarbon content and the most stable. But at the same time, we should consider the wind direction and abnormal environmental changes, such as forest fires, abnormal emissions of hydrocarbon gases, and the explosion of the "80000" air separation plant in Bintulu, the direct cause of which is the forest fires in Indonesia. The explosion of Fushun ethylene "6000" air separation tower was mainly caused by the inhalation of exhaust gas from the shutdown of chemical plant. The explosion of "3200" air separation unit in Yanshan Qianjin Chemical Plant was caused by the high hydrocarbon content in the upper part of the main cold liquid oxygen surface. After the qualified air entered the air separation unit, the hydrocarbons must be removed and some hydrocarbons must be adsorbed in the molecular sieve adsorber. If a layer of mixture is added, almost all hydrocarbons can be adsorbed, and at the same time, most hydrocarbons that have not been blocked by the design and manufacturing unit of the nitrogen oxide equipment can be adsorbed. The removal expansion air entering the low-temperature area is washed with liquid; The design and manufacture unit with liquid air adsorption filter removal equipment 2 measures to remove hydrocarbons in liquid oxygen. If hydrocarbons still enter liquid oxygen after passing through various checkpoints, the following measures should be taken (see Table 2). Table 2 measures for removing hydrocarbons in liquid oxygen remarks strictly stipulate the quantity of acetylene and hydrocarbons in liquid oxygen. The regulations vary from country to country, but they all have their own reasons. We must strictly abide by the design and manufacturing unit, and the user sets up a recording analyzer; It is necessary for the administrative leaders of the manual analyzer to stipulate the design and manufacturing unit in the form of documents. The "6000" air separation unit of Fushun Ethylene explosion is not set. After exceeding the standard, the liquid oxygen must be discharged in time, and the direct shutdown must be strictly implemented. The long-term and continuous discharge of 1% liquid oxygen by the user must be strictly implemented; It is very effective to solve the accumulation of saturated hydrocarbons. Design and manufacturing units, users set up liquid oxygen circulating adsorbers to further adsorb hydrocarbons, and use liquid oxygen pumps or heat pumps to circulate liquid oxygen; Users strictly implement the switching cycle design and manufacture of GFRP anchor bolt tensile testing machine unit of Jinan testing machine factory. The effect of heat pump with gas nitrogen as heat source is not good. 3. Measures on selection and operation improve the evaporation process during operation to avoid small explosion or large explosion; At the same time, attention is also paid to the selection of equipment and materials, and the measures taken are shown in Table 3. Table 3 measures for selection and operation measures content selection of reasonable condensing evaporator selection of reasonable condensing evaporator if it is a membrane condensing evaporator, a coiled auxiliary condensing evaporator can be used. The designer and manufacturer can control the evaporation capacity. When liquid oxygen passes through the evaporator, the evaporation capacity is controlled at 1/5, that is, the internal circulation ratio is greater than 5; Do not reduce the temperature difference too much. The full immersion operation of the designer and manufacturer is not applicable to the membrane type. The designer and manufacturer reduce the cold loss, stabilize the liquid level, control the expansion amount, and make the liquid level of the condensation evaporator rise slightly. The correct selection of user materials in the high oxygen area is better not to use aluminum, and use copper (such as the packing layer of the tower close to the main cold place) to design the manufacturer 4. Measures to avoid the dry evaporation of liquid oxygen in local areas. All dust, molecular sieve and silica gel powder, carbon dioxide particles Nitrogen oxide precipitates, metal powder, pearlescent sand - these solid particles may block up a small space, which is easy to "sew" lightweight and high-strength composites with carbon nanotubes! Local dry evaporation is formed, causing a small explosion and even a big explosion. See Table 4 for the measures taken. Table 4 measures to avoid dry evaporation of liquid oxygen in local areas remarks: wash the compressed air with water as much as possible. The designer and manufacturer shall ensure the cleanliness of the manufacturing process and the cleanliness of the installation process. The designer and manufacturer and the installer shall filter the dust to remove molecules

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