Large air separation FAQ

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

1. The removal of perlite site shall be supervised by full-time personnel and guided by professionals. The principle of who organizes, who takes responsibility shall be followed. There should be a safe passage and a warning line at the removal of perlite site, and it is strictly forbidden to enter. 2. Dry air shall be used to warm the sand during the removal and knock the cold box to remove the pearlite caking, so as to prevent equipment damage caused by falling caking. 3. The removal of perlite should be carried out in layers and sand holes should be opened at different heights of the cold box. (It can be adjusted according to the site conditions) 4. In the process of removal of perlite, always supervise the caking on the top and enter the cold box for cleaning at any time. 5. In case of severe weather such as rain, snow, strong wind or sand storm danger, the construction party and the owner shall jointly confirm that the sand stripping work shall be postponed. 6. Remov

The reflux liquid in the upper column of the distillation column is throttled by the lower column to the liquid air and liquid nitrogen of the upper column, and the reflux ratio of the upper column is regulated by the liquid nitrogen throttle valve. When the liquid air and liquid nitrogen pass through the throttle valve, the pressure will decrease, and the corresponding saturation temperature will also be reduced. If the supercooling degree of liquid is not enough, some liquid will be vaporized. The higher the gasification rate is, the lower the reflux ratio of the upper column is, and the purity of nitrogen is affected. Therefore, in order to improve the supercooling degree of the liquid nitrogen in the night sky through the throttle valve, a subcooler is generally set up to increase the supercooling degree of the liquid nitrogen in the liquid air.

After a long-term operation of the air separation plant, the components in the cryogenic equipment and pipelines in the distillation system will be blocked due to ice or mechanical powder, which will increase the resistance of the fractionator. When the air separation plant has been in normal operation for about 2 years, the fractionator system should be heated and thawed to remove these deposits. When the molecular sieve adsorber and the main heat exchanger have water inflow or other faults, it is also necessary to stop and heat up. In general, the following methods will be used for heating and thawing.

After a long-term operation of the air separation plant, the components in the low-temperature equipment and pipelines of the distillation system will be blocked due to the internal precipitation of icing or mechanical powder, which will increase the resistance of the fractionating column. Therefore, after the normal operation of the air separation plant for about 2 years, the fractionating column system should be heated and thawed to remove these sediments. When the molecular sieve adsorber and the main heat exchanger have water or other faults, they must also be stopped for heating. The following describes several heating and thawing operation methods: