What is the working principle and function of the request drain evaporator?
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What is the working principle and function of the drain evaporator in ASU? What issues should be paid attention to during on-site installation? Thank you.
The liquid discharge evaporator directly discharges low-temperature liquids (liquid oxygen, liquid nitrogen and liquid argon) into the atmosphere, but liquid oxygen, liquid nitrogen and liquid argon cannot be completely vaporized (the liquid-gas state is converted at a ratio of about 1:800). Since liquid oxygen is a combustion-supporting medium, it is easy to burn and explode when exposed to open flames. Liquid nitrogen and liquid argon can easily suffocate people. Therefore, if they are not safely discharged, the surrounding environment will be polluted and become a source of danger, the consequences will be serious. The liquid discharge evaporators I have seen use the air volume of the blower to evaporate a certain amount of liquid oxygen, liquid nitrogen and liquid argon, and have achieved certain results. However, it is difficult for the blower to be used for large-scale air separation equipment, and it is easy to cause poor or even failure to discharge the liquid, making the equipment unusable. Large-scale air separation equipment mostly uses steam jet liquid discharge evaporators, but I don’t know much about its structural principles. I’m looking forward to experts’ answers!
The steam jet discharge evaporator is not necessarily good. Every time it is discharged, the direction of the outlet is like hail falling, which is not safe. Many of them lead air directly from behind the air compressor for vaporization.
Our factory uses steam heating for evaporation. The oxygen and nitrogen drain evaporators are separate from the argon system drain evaporator. There is a low temperature interlock at the exhaust gas discharge port and a low pressure interlock on the steam side to ensure safety.
The steam drain evaporator leads all drain drains to the drain main pipe and connects it to the drain main pipe. Steam is passed through it and there is temperature control. When the temperature is low, the steam valve opens automatically and nitrogen is normally passed through to keep it dry.
The liquid discharge evaporator in our factory uses the air volume of the fan to evaporate a certain amount of residual liquid, and part of it is discharged into the stone volatilization tank to evaporate naturally. However, many large-scale air separation equipment in China mostly use steam jet discharge evaporators. The steam jet discharge evaporator mainly consists of two parts, one is the cryogenic liquid tube inlet and the shell side, and the other is the steam injection part. The overall horizontal structure is adopted, and the cryogenic liquid tubes are arranged horizontally, so that the evaporation space is relatively large. The characteristics of this structure are:: 1. Ensure that the evaporated gas has a certain temperature and will not cause atmospheric condensation. 2. The low-temperature liquid can be fully vaporized and will cause no harm to humans and no pollution to the environment after discharge. The purpose of the steam jet liquid discharge evaporator is to safely discharge the cryogenic liquid from the air separation unit. Its technological process: The medium low-temperature liquid enters the tube side horizontally through the relevant port, and is ejected through the small nozzle hole opened on the tube side. The high-temperature, high-pressure saturated steam entering the tube mouth is sucked into the air in the state of jet flow and mixed with it. Due to the high steam pressure, large heat, and large evaporation space of low-temperature liquid, the large-scale steam jet discharge evaporator has small resistance in the discharge process, smooth discharge, and good use effect, achieving the goals of safe production, improving efficiency, and protecting the environment!
Please ask the original poster "What is the working principle and function of the drain evaporator in the ASU?" What does ASU mean? Thanks!
The discharge device of liquid oxygen and liquid air is called a residual liquid evaporator in our branch. This is a normal pressure device that can be welded by itself. The material is 0Cr18Ni9. Is it resistant to low temperatures? The pipe diameter does not need to be too large. Generally, DN400~500 is enough. A height higher than 5 meters should generally be sufficient. Back pressure steam is used at the bottom. The current back pressure steam in our branch is 1.3MPa (gauge pressure). When draining liquid, open the drain valve and steam inlet valve, and use steam to vaporize the liquid and bring it into the air. If the liquid drops, adjust accordingly, that is, increase the steam flow rate or reduce the liquid drain volume. When draining liquid, pay attention to the surroundings and wind direction. It is forbidden to use fire at the entrance where the natural wind flows. Barriers should be set up at the corresponding intersections to prohibit the passage of motor vehicles and people. Because the evaporated liquid oxygen has a combustion-supporting effect, motor vehicles may produce open flames, causing fires or even more dangerous phenomena. The effect of electric welding is even more obvious! Prohibiting people from passing through is to prevent the water from being emptied from the top to freeze and fall down and hit people. P.S.: Relevant staff should wear safety helmets!
ASU stands for Air Separation Units, as foreigners call it.