When the expander is running at full load, the liquid level stops, and the small liquid nitrogen control valve should be closed gradually until it stops working. Grasp the timing and speed of valve closing. If the closing speed is too slow or too late, the intermediate temperature of the plate heat exchanger will be too low, resulting in supercooling, so that the temperature before expansion is too low to be adjusted; if the closing speed is too early, the air flow into the tower will be reduced. The gas used in the cold blowing period is still dirty nitrogen, which will not be heated again. Obviously, the temperature of the gas entering the molecular sieve bed will decrease rapidly, and the temperature of the bed near the inlet side will also decrease. As the heat flows to the nitrogen outlet side, the bed at the outlet side will continue to rise, and this part of molecular sieve will continue to regenerate.

A certain amount of air contains more water vapor, the air will become moist; less water vapor, the air will become dry. Therefore, the dry humidity of the air can be expressed by the amount of water vapor per cubic meter of air, that is, the absolute humidity of the air in kg / m3 (or g / m3). The main method for air separation equipment manufacturers to adjust the intermediate temperature is to adjust the proportional relationship between forward and reverse flow. Frequently used are: to change the middle extraction volume or circulation; to change the air flow distribution among the groups of the cold storage (or heat exchanger), or to produce oxygen and nitrogen distribution, and so on. For example, if the temperature in the middle is too high, you can close the small intake valve, reduce the intake volume or increase the circulation flow (or intermediate suction volume).

The main coolant is generated and accumulated from the liquid air throttling of the lower tower to the upper tower. At this time, liquid air appeared in the tower body and throttled to the upper tower. After throttling, some liquid gasified and the temperature further decreased. Depending on these low-temperature liquids and gases, they continue to cool at the top of the tower. The factors that affect the evaporation boiling intensity of air separation equipment manufacturers are: unit heat load (heat transfer per unit time, unit area), pipe geometry size and liquid level height (ratio of pipe static liquid level height to pipe length). The experimental results show that the relative height of liquid surface is between 0.3 and 0.4, and the boiling heat transfer coefficient is larger when the tube geometry and heat load are constant;

The naked cooling method of air separation equipment manufacturer is the low temperature detection of air separation equipment. The objectives are: 1) to check the installation or maintenance quality of the air separation unit; for example, to check whether there are leakage points in the pipeline welds and flange joints; 2) to check the cold deformation and compensation capacity of the air separation unit, pipelines and valves at low temperature; 3) to check whether the equipment and pipelines are smooth and correct; 4) to further tighten the butt flange screws at low temperature to ensure that there is no leakage at low temperature There's a leak. If there is no dry gas, the cooling water will reach saturation in the process of blowing, and it is likely that the cooling water will precipitate from the inside of the equipment, or even freeze, causing pipes and equipment to freeze. In addition, when the temperature of the wet gas remaining in the equipment changes, it is easy to cause water drop precipitation. To achieve the purpose of equipment drying, blow out the best drying air flow.

Neon and helium in the air separation plant occupy part of the condenser, which makes the heat exchange area unable to be fully utilized. For example, when the 6000m3 / h oxygen generator gathers at the top of the main cooling layer for 8 hours, neon and helium are about 6m3. So much non condensable gas will seriously affect the normal operation of condensing evaporator. There are both air and backflow gas in the pipe, so the temperature of hot blowing period (air passage) and cold blowing period (gas passage) can be measured. The resistance thermometer measures the cold end temperature at the bottom of the accumulator. The following shows how to determine the temperature state of the accumulator and calculate the temperature difference between the hot end and the cold end of the accumulator with some measured data.