Air separation parts FAQ

It should contact with the front and rear processes when the piston compressor is ready to stop, we should pay attention to the following sequence: first, cut off the gas supply slowly. In order to prevent the outlet pressure from rising after the gas supply is cut off, open the vent valve at the same time. For the oxygen compressor, the vent valve should be opened slowly, because excessive opening may produce static electricity and cause fire. Then, stop the motor. After the motor stops, turn off the circulating oil pump, grease injector motor and cooling water valve. However, there are also exception cases. For example, in case of emergency shutdown, in order to save time and prevent the accident from expanding, the power supply can be cut off immediately to stop the compressor with load.

There are four kinds of commonly used thermometers in air separation plant: industrial internal standard glass thermometer, thermocouple thermometer, thermal resistance thermometer and pressure gauge thermometer. According to the principle of temperature measurement, the range of temperature measurement and whether it can be transmitted remotely, four kinds of thermometers are used in different temperature measuring occasions of air separation plant. Industrial internal standard glass thermometer is used in small air separation plant to measure the temperature of all levels of compressor gas and cooling water locally, and it is also used for temperature measurement during heating and thawing; thermocouple thermometer is used for purifier; thermal resistance thermometer is used for low temperature measurement inside cold insulation box; pressure gauge thermometer is used for measuring lubricating oil temperature.

In the air separation unit, low-temperature liquid is transported by centrifugal cryogenic pump. In order to ensure the reliable operation of the equipment, two sets of low-temperature pumps are generally equipped, one for use and one for standby. During normal operation, the main pump runs at full load, and the standby pump is in standby state under low load operation. Since the working medium temperature of cryogenic liquid pump is about -180°C, the working pressure is very high, and the pump body is installed in the cold box. When the pump fails, it is extremely difficult to maintain. Therefore, how to maintain the stable and reliable operation of cryogenic liquid pump is of great significance.

Expander is a kind of equipment that uses the principle of mechanical work output when compressed gas expands and depressurizes to lower the temperature of gas. Expander is the key equipment to provide cooling capacity for air separation plant. The efficiency of expander directly affects the operation effect of air separation plant. The following introduces several factors that cause the efficiency reduction of expander.

Centrifugal compressor is widely used in petrochemical, metallurgy and other industries because of its large exhaust volume, high operating efficiency, simple structure, small area coverage, stable operation and no pulsation of compressed air.

Users equipped with piston compressors often encounter the phenomenon of pipeline displacement, support deformation and severe noise caused by pipeline vibration, which has a negative impact on safety production. Therefore, it has great significance to thoroughly solve the vibration problem of the pipeline of the piston compressor to ensure the safe production of the air separation plant.

According to a DEAR air separation user, during the operation of a set of air separation plant that has been in operation for 5 years, it is found that under the condition that the inlet guide vane does not change, the expansion air volume of the expander gradually decreases, and the rotation speed of the expander gradually decreases, the outlet pressure of the booster end of the expander rises from 0.76MPa to 0.8MPa, the inlet temperature rises from - 110 ° C to - 95 ° C, and the working condition of the chilled water pump is poor.

The liquid oxygen pump is a kind of low temperature liquid pump. It is used as the liquid oxygen circulating pump in the main condensing evaporator in the internal compressed air separation process to increase the pressure of liquid oxygen and output liquid oxygen.

The deflagration of the oxygen compressor will cause great harm to the safe operation of the air separation equipment and the personal safety of the operators. Each air separation user should attach great importance to the safe operation of the oxygen compressor to prevent the occurrence of the deflagration accident.

In the temperature of the forward air into the cooler (hot end temperature, related to the cooling effect of the last cooler of the air compressor or nitrogen water precooler) and the temperature of the return air into the cooler (cold end temperature, under the condition that the temperature of the heat exchanger such as the outlet supercooler and the liquid purifier is not changed, the temperature difference between the thermal end and the temperature difference between the cold end of the refrigerator (both refers to the difference between the temperature of the forward air and the reflow gas participating in the switching) is interdependent. If the hot end temperature difference, cold end temperature difference will is too small; the hot end temperature difference is too small, cold end temperature difference will is too large. This is decided by the cooling balance of the positive and return gas of the cooler. When the ratio of return flow to positive flow volume is larger than...

The temperature condition adjustment of the cooler (or switching heat exchanger) is based on the central temperature. The "middle" mentioned here does not refer to the central position of geometric dimension, but refers to the temperature on the barrel (or switching channel) near the central air extraction or the outlet of circulation. It is also related to the location where the thermometer is installed. The purpose of temperature condition adjustment is to keep the temperature difference between cold end and hot end within the specified range. Then, why should the temperature in the middle prevail? We need to take a look at the relationship between the temperature of the middle part and the temperature difference of the cold end and the temperature difference of the hot end, and what rules the temperature changes along the height direction of the cooler (or the switching heat exchanger) follow. The temperature condition change of the cooler (or switching heat exchanger) is general...

The start-up phase of the whole low-pressure oxygen generator is that liquid empty appears first in the lower tower, and then liquid oxygen appears in the upper tower. The cold energy needed to accumulate liquid in the tower mainly comes from the expansion machine, which uses the low temperature gas after expansion to make part of the air liquefaction in the liquid purifier. But the upper tower itself can not produce liquid, it mainly depends on the liquid from the lower tower into the upper tower. In the phase of hydrops, in order to accumulate the liquid level as soon as possible, the cooling volume should be transferred to the tower as much as possible, the phenomena of overcooling, temperature difference at the hot end and cold loss increase caused by excess cooling of switching heat exchanger should be avoided. As for how to recycle and transfer the cold volume of the air expansion into the tower, whether it is by the liquid purifier to transfer the cold volume to the lower tow...