Large air separation FAQ

1. When working at a height of more than 2 meters or multilevel cross operation, special personnel shall be assigned to guard or contact with each other, and it is strictly forbidden to command by more than one person. 2. The safety belt must be worn when working at a height of more than 2 meters, and it should be hung high and low. It is forbidden to hang the safety belt on the maintenance objects, on the pipelines and equipment (including electrical) of various dangerous media, and it is forbidden to drag the safety belt on the ground. It is strictly forbidden to use nylon material safety belt in high-temperature area or welding operation, and the flame-retardant and high-temperature resistant safety belt should be selected. 3. If there are high falling objects, the articles should be cleaned up in time, or the falling prevention measures should be added. 4. The safety rope should be lowered from the top of the silo as the hanging point of the safety belt for the high-altitu

1. According to the specific situation of the construction, formulate the fire protection scheme, establish and improve the fire safety system, and strictly abide by the operation rules. 2. Flammable and explosive materials such as paint and thinner shall not be stored in the project site. 3. The construction unit is not allowed to set up seasoning room in the project, and is not allowed to carry out paint allocation in the project. 4. No smoking is allowed in the construction site. A fire permit shall be issued and a special person shall be assigned to supervise the operation. 5. The operation site should be equipped with sufficient fire-fighting equipment. 6. During the construction period, the use of various open fire operations in the project shall be approved by the safety and environmental protection department of the construction unit, and sufficient fire-fighting materials and fire-fighting equipment shall be provided.

With the development trend of large-scale air separation plant, the column support of its matching cold box equipment tends to be large-scale. The traditional support structure has complex structure and poor bearing capacity. Through the use of finite element analysis software, DEAR air separation carries out finite element analysis and optimization on the commonly used experienced column of air separation plant, so as to improve the bearing capacity of support and reduce the processing difficulty, to reach the purpose of saving material cost.

According to the adsorption characteristics of molecular sieve, there are two kinds of air purification process, one is pressure swing adsorption molecular sieve purification process, the other is temperature swing adsorption molecular sieve purification process. Pressure swing adsorption can simplify the process, save air cooling column, low temperature water pump, regeneration heater and other equipment, and save steam. However, its disadvantages can not be ignored, such as short switching cycle, frequent valve action which could cause default, high switching loss, increased energy consumption, adsorption is not completely compared with temperature swing adsorption, which has an impact on the safety of large-scale air separation, and the total investment is slightly greater than that of temperature swing adsorption. Therefore, we mostly use the temperature swing adsorption molecular sieve purification process.

1. The requirements of molecular sieve adsorber, electric heater and other equipment in place are the same as those of air cooling column of pre cooling system. 2. Process piping shall be constructed in strict accordance with relevant specifications and design and construction drawings. 3. The air tightness test shall be conducted before the valve is installed, and the test pressure and inspection standard shall be carried out according to the technical requirements of corresponding valves. 4. Pay attention to the direction of switch valve installation. V1201, V1202, V1207 and V1208 are front mounted valves, while V1203, V1204, V1205 and V1206 are reverse mounted valves. When the switch valve is installed, its shaft should be in a horizontal position, and the flange bolts should be evenly cross tightened. 5. The pipeline of pressure equalizing valve V1209 should have compensating bend.

The principle of expander with motor brake in air separation plant is to control the speed of expander by braking torque generated by motor generator braking state. Once the brake motor fails, the expander speed will lose control and overspeed will occur. At this time, it is necessary to automatically open the protection and control system. The principle is that the speed measuring motor will send out the overspeed signal to cut off the three-way solenoid valve. The three-way solenoid valve directly controls the air open pneumatic butterfly valve at the inlet of the expander, so that the butterfly valve is quickly closed and the air inlet is cut off. At the same time, the rotation of the valve rod touches the stop and limit switch, so that the power supply of the expander motor is cut off and the safe shutdown is realized.

In the operation of air separation plant, in order to ensure the accuracy of DCS control system monitoring and the safety and stability of operation, it is necessary to do well of DCS system grounding.

The upsizing of air separation plant has became an inevitable trend of the development of national economy. A few years ago, the domestic air separation industry had achieved the air separation performance of 100000 m³/h level, and there were more than 150000 m³/h air separation plant abroad. With the gradual increase of the scale of air separation plant, its energy consumption is also increasing. In order to save energy, reduce consumption and reduce pollution, it is of great significance to study the driving mode of compressor for large-scale air separation plants. 1. Turbine drive: Steam turbine is widely used in electric power, chemical industry, metallurgy and other industries and fields because of its axisymmetric high-speed rotation characteristics, smooth operation, small wear and long continuous operation time. However, the one-time investment of steam turbine drive is relatively large, and the requirements for heat supply pipeline and production system are high. The pla

In order to check the installation quality, deformation under low temperature and smooth condition of pipelines, valves and field installed air separation plant in air separation column, needs to be further tighten the flange bolts at low temperature. It is necessary to start freezing before filling the cold insulation box with cold insulation material, which is called naked cooling. During naked cooling, the rectification column, main condensing evaporator and other main equipment shall be cooled to the minimum temperature for 2 hours respectively, and then the whole air separation unit shall be cooled for 3 to 4 hours. The deformation and leakage of each part shall be checked in detail, and the flange bolts shall be tightened again. After defrosting, the flange shall be heated to normal temperature before gas seal test can be conducted.

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.

When the air is out of the air compressor, due to the compression, the moisture in the air is in the saturated state. After the water cooling column decreasing the temperature, the water content in the saturated state decreases, and the excess water condenses into the water. The water volume in the air cooling column increases and the water temperature rises. But not only is the temperature of the air reduced, but also the moisture content of the air. In the water cooling column, the crude nitrogen is used to cool the water. After passing through the main heat exchanger from the fractionator, the temperature of the crude nitrogen is close to the normal temperature, but it is very dry. The dry crude nitrogen contacts with the water, and a large amount of water is evaporated into the crude nitrogen by using the unsaturation of the crude nitrogen, which absorbs the heat of the water and reduces the water temperature.

Thermodynamic energy is the sum of kinetic energy of irregular motion of molecules in matter and potential energy generated by mutual attraction between molecules. In the process of oxygen production, there are many flow processes, such as compression, expansion, heating and cooling. These processes not only involve the change of thermodynamic energy, but also involve the transformation between the flow energy and the thermodynamic energy. Enthalpy is the sum of material thermodynamic energy and material flow, so it is more convenient to study these flow processes with enthalpy.