Large air separation FAQ

In general, the liquefaction temperature of nitrogen is higher than that of oxygen, but why can the condensation evaporator between the upper and lower columns of the air separation column use gas nitrogen condensation to release heat to vaporize liquid oxygen? This is because we usually think that the liquefaction temperature of nitrogen is lower than that of oxygen under the same pressure. However, the pressure at the bottom of the upper column of the air separation unit is generally 0.149 MPa, and the pressure at the top of the lower column is about 0.58 MPa. The reason for the different pressure causes the inversion of the saturation temperature of oxygen and nitrogen. It is precisely by using this principle that the condensing evaporator can continuously provide liquid nitrogen for the lower column At the same time, it provides gas oxygen for the upper column as the rising gas to participate in fractionation.

In the air separation plant, the purity of oxygen is mainly determined by the working conditions of the distillation column at the upper and lower parts. In addition, the oxygen content in argon fraction, reflux ratio, number of theoretical trays and separation efficiency will have a direct impact on the purity of oxygen. The following is a brief introduction to the relationship between these factors and oxygen purity.

During the normal operation of the air separation plant, the temperature of each part of the cold box should be kept in balance. However, due to the temperature difference at the hot end of the heat exchanger and the possibility of no heat transfer between the cold box and the environment, and some large-scale air separation plants may produce a small amount of liquid products, which will cause heat loss. Therefore, to supplement the lost cooling capacity through expander and throttling, we paid electric energy to get the cooling capacity of expander. Why can throttling produce cooling capacity? This is because the pressure decreases after throttling, and the throttled liquid air and liquid nitrogen are saturated liquid. The pressure drop naturally causes the saturation temperature to decrease. In order to maintain its saturation state, part of the liquid is gasified to absorb heat.

Steam turbine is a kind of turbine mechanical equipment that converts heat energy of steam into mechanical energy. In air separation plant, steam turbine is used as power source of air compressor instead of motor, which saves a lot of power consumption for air separation users, so it is widely used in air separation field.

With the rapid development of national economy, cryogenic air separation plant has been widely used in petrochemical, glass, tire, polysilicon, carbon fiber and other industrial fields. The nitrogen production process consists of air compression and purification, air separation and liquid nitrogen vaporization.

1. Enter the work area, wear all kinds of labor protection equipment; check the surrounding working environment; confirm the tools and machines; prohibit the use of defective tools. 2.When using the sledge hammer, it is forbidden to wear gloves; it is strictly forbidden to stand in the range of before, after, up, down, left and right of the sledge hammer, and no one is allowed to stand on the opposite side to prevent injury. 3.Before welding operation, it is necessary to carefully check whether the electric welding tools used are insulated, whether the primary and secondary wires of the welding machine are damaged, and whether the grounding wire is in good condition; insulating gloves must be worn to prevent the occurrence of electric shock accidents when the welding machine stops power transmission and switches on. 4.The safety protection facilities of oxygen cylinder and acetylene cylinder should be complete and reliable. When working, the distance between oxygen cylinder an

When the new air separation plant is purged the first time, the air compressor pressure shall be increased to the quota pressure as far as possible. The purge valve should be fully opened as far as possible. Since the drain valve is connected together, the pressure is different. Therefore, when purging the drain valve, should purge one by one, and then close one after another for half an hour. After purging, do not fully close the purge and drain valves. Shut down the air compressor and wait until there is no pressure. Take all the valve bodies of the purge and discharge valves to check and clean, and then restore them. Only in this way can the purging be qualified.

Users reported that the on-line analyzer of a 30000 grade air separation plant showed that the outlet CO₂of the molecular sieve suddenly increased from the normal value of 0.43×10-6 to 120×10-6, and the temperature difference in the expansion air channel entering the two high-pressure plate fin heat exchangers began to expand. At the same time, the temperature in front of expander also decreased from - 105°C to - 132°C with liquid entrainment. After receiving the user's notice, DEAR air separation sent technical personnel to the site for observation and detection. It was found that the location of the self-cleaning filter of the equipment was close to the chemical boundary area. When the wind direction was in the downwind direction of the chemical industry boundary area, the phenomenon that the concentration of CO₂ in the air at the inlet of the self-cleaning filter of the air compressor exceeded the standard. In view of this phenomenon, the following opinions are given: 1. Sh

In the commissioning process of argon production system of new air separation plant, due to unstable gas demand and other reasons, the working condition of argon production system is easy to be fluctuated. The following is the analysis and treatment of common faults. 1. The nitrogen content in argon fraction increased Due to the small extraction amount of nitrogen products and crude nitrogen products, part of nitrogen enters into the argon production system along with argon fraction, resulting in the increase of nitrogen content in argon fraction. As a result, the temperature difference between oxygen enriched liquid air and crude argon in crude argon condenser is reduced, and normal heat exchange cannot be conducted. Finally, the crude argon cannot be condensed and the oxygen enriched liquid air cannot be evaporated. During the adjustment, the extraction amount of crude nitrogen and nitrogen is provided to reduce the outlet pressure of crude nitrogen to maintain normal operation c

The environmental conditions considered by the air separation plant include: altitude, atmospheric pressure, ambient temperature, air humidity, the content of impurities such as carbon monoxide in the air, etc. These conditions vary with different regions and environments. Different environmental conditions have different effects on the performance of the same air separation plant. 1. Influence of atmospheric pressure on air separation plant: Atmospheric pressure is the pressure exerted on objects in the atmosphere by the gravity of the atmosphere itself. In general, the atmospheric pressure is about 0.1MPa. When the atmospheric pressure decreases, the compression ratio of the air compressor will increase, which will increase the energy consumption of the air separation plant. 2. Influence of ambient temperature and humidity on air separation plant: The increase of ambient temperature will reduce the air compressor's exhaust volume, increase the exhaust temperature, increas

With the development of social economy, the air separation plant is in the trend of large-scale development. Air separation plant, as a large energy consumption user, is affected by domestic environmental protection and resource problems. It has great significance on the development of enterprises and the improvement of economic benefits to select a reasonable compressor driving mode.

Air separation plant is an important supporting facility for large-scale industrial enterprises, such as chemical industry, smelting industry, electronics industry and energy industry. Its operation condition is very important to the enterprise. In the actual production, the air separation plant is often be shut down by mistake due to many factors, such as instrument control incorrect interlocking, manual incorrect operation or network voltage fluctuation, which causes great losses to the enterprise. Here are a few preventive measures for incorrect shutdown.