Large air separation FAQ

In order to reduce the air temperature in the low temperature air separation unit, various heat exchange equipment are needed for cold and heat exchange in various air separation systems, such as nitrogen water precooler, switching heat exchanger, main heat exchanger, condensing evaporator, subcooler, liquefier, vaporizer, electric heater, etc. These heat exchange equipments are installed in each system of the air separation unit, which are necessary for air liquefaction and gas separation. According to the principle of heat transfer, the heat exchanger of air separation unit can be divided into three types: 1. Dividing wall type: the cold and hot fluid is separated by the heat transfer wall, the medium does not directly contact in the heat transfer process, and the hot fluid transfers heat to the cold fluid through the heat transfer wall. For example, tube heat exchanger and plate heat exchanger. 2. Heat storage type: the cold and hot fluid alternately flows through the solid

The water supply source of air cooling column in precooling system equipment is cooling water pump, and water cooling column is supplied by chilled water pump. Their structures and principles are described as follows: 1. Design structure: the most basic components inside the centrifugal pump are high speed impeller and fixed volute pump case. Generally, the impeller with several (4 ~ 12) backward curved blades is fixed on the pump shaft and driven by the motor to rotate with the pump shaft at high speed. The work done by these impellers will directly act on the liquid in the pump body, which is the energy supply source device of centrifugal pump. 2. Principle: after the centrifugal pump is started, the pump shaft directly drives the reverse curved impeller to move at high speed, squeezing the pre filled liquid between the reverse curved spaces of the blade to rotate. Under the high-speed centrifugal force formed by the movement of the pump shaft, the liquid moves radially from th

Due to improper adjustment of seal gas pressure during operation, liquid oxygen pump can not pump liquid or leak.   From the quality point of view, when the sealing pressure is too high, there will be gas leakage into the pump through the labyrinth seal, resulting in the impeller with gas or even idling, resulting in liquid injection or pressure drop; when the air pressure before sealing is too low, there will be liquid oxygen leakage.   From the quantity point of view, when (p1-p3...

In the air separation unit, the function of air cooling column is to reduce the temperature of air compressed by air compressor. Air cooling column is a kind of hybrid heat exchange equipment. In order to increase the heat transfer area, make the cooling water fully contact with the air and mix completely to enhance the heat transfer effect, the air cooling column usually adopts several structural forms such as packed column, sieve plate column or hollow spray column.

In the air separation unit, the water cooling column is a hybrid heat exchange equipment which uses the crude nitrogen to reduce the temperature of the cooling water from the air cooling column after cooling air, so as to provide the air cooling column with recycling. In the water cooling column, the crude nitrogen from the reversible heat exchanger (or accumulator) is 27-28 ℃ and the relative humidity is about 30%, while the temperature of the cooling water from the air cooling column is 35-45 ℃. When the crude nitrogen meets the hot water sprayed, it absorbs heat, thus reducing the water temperature. Generally, the structure of water cooling column is packed column, cyclone plate column and sieve plate column.

The leakage of unit or pipeline in the cold box needs removal of perlite treatment. Since it is uncertain whether there is a leakage point in the cold box, it will have a certain impact on removal of perlite. No matter whether the leakage is liquid or air, the sand filling holes at the top should be opened first, so that the residual gas in the cold box can be slowly discharged into the atmosphere. The oxygen content of the gas in the cold box and the pressure indication in the cold box should be strictly monitored in removal of perlite process. In the process of sand stripping, it is particularly important to avoid the formation of sand free area in the middle of the cold box, so as to avoid sand storm caused by the sudden drop of pearlite sand.

According to the dye composition of penetrant, it can be divided into fluorescent penetrant testing, dye penetrant testing and fluorescent dye penetrant testing, which are represented by I, II and Ш respectively. According to the penetrant removal method, it can be divided into water washing type penetrant testing, lipophilic post emulsifying penetrant testing, solvent removing penetrant testing and hydrophilic post emulsifying penetrant testing, which are represented by A, B, C and D respectively; according to the type of imaging agent, it is divided into dry type Powder imaging agent, water soluble imaging agent, water suspension imaging agent, solvent suspension imaging agent and self imaging were expressed as a, b, c, d, e, respectively. II Cd means solvent removal dye penetrant testing, and the imaging agent is solvent suspension type.

There must be enough smooth straight pipe sections before and after the flow orifice plate. The distance is 10 times of pipe diameter in front of the orifice plate and 5 times of the pipe diameter behind the orifice plate, and no factors affecting the measurement accuracy (such as pipe joint, etc.) are allowed. The inner surface of the pipe weld should also be ground smooth, and the gasket should not extend into the inner diameter of the pipe. And carefully check the installation direction of the orifice plate, do not install it in reverse. (judgment method: the small exit is the entrance, and the large exit is the outlet)

In the air separation unit of molecular sieve adsorption purification process, after the air is compressed at the last stage of the air compressor, the temperature out of the air compressor reaches 80-90 ℃. Since the adsorption capacity of molecular sieve is inversely proportional to the temperature, in order to improve the working efficiency of molecular sieve adsorber and ensure the purification effect, the compressed air from the air compressor must be cooled to reduce the temperature of the compressed air before entering the purification system.

The oxygen and nitrogen products produced by the air separation unit in the external compression process are low-pressure oxygen and nitrogen from the upper column, which are sent out of the cold box after being reheated by the heat exchanger. The product gas pressure out of the cold box is generally 0.12MPa. After being compressed to the pressure required by the user by the oxygen compressor, it is sent to the user’s pipeline. The internal compression process of oxygen is that liquid oxygen products are directly extracted from the condensing evaporator, compressed to the user's required pressure by the liquid oxygen pump in the cold box, and then sent to the user's pipeline after reheating and gasification by the heat exchanger.

1. Before hoisting, check and confirm whether the crane body, crane legs, lifting rigging and wire rope meet the safety requirements and hoisting conditions. 2. The hanging points of hoisting facilities shall be confirmed to prevent deviation and inclination; steel wire rope or sling shall be used for protection of edges and corners; sling and U-ring shall be used for lifting objects. 3. The commander shall use inter-phone for command, and special personnel shall be assigned for command, and the personnel shall stand at the position where the lifting object can be fully observed; warning isolation shall be set up in the hoisting area, and no one shall stand under the lifting object. 4. For large-scale hoisting, the hoisting safety scheme shall be formulated in combination with the company's special operation system.

1. Adhere to the electrical professionals to work with certificates, non electrical professionals are not allowed to replace or repair any electrical components. 2. Establish the temporary electricity inspection system, inspect and irregularly inspect various lines and facilities on site according to the temporary power management regulations, and archive the inspection and spot check records. 3. The inspectors and operators must wear insulating rubber shoes and gloves according to the regulations; they must use special insulating tools for electricians. 4. The temporary distribution lines must be erected according to the specifications. The overhead lines must be insulated wires, plastic flexible wires, bundles of overhead laying and surface laying along the ground. 5. The erection and use of temporary electricity on the construction site must comply with the provisions of technical code for safety of temporary electricity on construction site (JGJ46-88). 6. Constructio