Air separation plant.When the low-pressure oxygen generator starts up, the cooling capacity of the main cooler needs to be consumed, and the cooling capacity required to cool it to the working temperature is also certain. Some people think that gas precooling and liquid air precooling in the second stage and the fourth stage both transfer part of the cooling capacity to the main cooler, and the effect should be the same. Therefore, the precooling of the main cooler is ignored, resulting in the supercooling of the switching heat exchanger in the liquid accumulation stage.Air separation plant.Low temperature air separation method: firstly, the air is compressed and expanded to reduce the temperature until the air is liquefied, and then the gasification temperature (boiling point) of oxygen and nitrogen is different (under atmospheric pressure, the boiling point of oxygen is 90K, and that of nitrogen is 77K). Nitrogen with low boiling point is easier to be gasified than oxygen.When installing the fractionator, attention must be paid to the two "vertical correction irons" on the outer side of the shell, and the verticality shall not be greater than 1 / 1000. If the fractionator is not installed vertically, it means that the tray is not horizontal. In this way, in the operation of the fractionator, the thickness of the liquid layer on the tray will be uneven, some places are thicker, some places are thinner, and some places even have no liquid.
In order to prevent the ground water from freezing, the foundation itself can be provided with ventilation holes, or the ventilation pipes can be buried in the soil layer under the foundation, and the drainage work around the foundation can be done well. The foundation elevation is generally 800-1000mm. In order to monitor the temperature change and elevation change of the foundation in use, temperature measuring points should be set up above and below the cold insulation layer and the bottom of the foundation, and settlement observation points should be buried around the foundation surface.In the rectifying tower, the steam with higher temperature and the liquid with lower temperature contact each other continuously, the nitrogen in the liquid evaporates more and the oxygen in the gas condenses more, so that the nitrogen content in the rising steam increases continuously and the oxygen content in the downstream liquid increases continuously, so as to realize the air-gas separation.Air separation plant.Nitrogen water precooler is widely used in all low pressure air separation units. It mainly makes use of the unsaturation of the water in the polluted nitrogen to make part of the water evaporate. When the water evaporates, it absorbs the latent heat of vaporization to reduce the cooling water temperature. Then it is used to cool the processing air and reduce the temperature of the air entering the tower. Therefore, it includes air cooling tower and water cooling tower.
Air separation plant.When l / di increases 5 times, the boiling heat transfer coefficient increases almost 2 times. Therefore, the condensing evaporators boiling in tubes are long tubes. However, the boiling heat transfer coefficient decreases with the increase of L / Di, and tends to be stable after L / di > 500, so it is generally taken as L / di < 500. Considering the manufacturing process, in fact, the pipe length is about 3M. At this time, the influence of static pressure of liquid oxygen column is still not great.We should give full play to the refrigeration capacity of several expanders, rationally distribute and utilize the cooling capacity, and shorten the start-up time by relying on the potential of the equipment itself. Because of the large heat capacity of the stone accumulator, it takes quite a long time to cool down to normal temperature after heating. The air from the turbine air compressor can be used to blow the packing close to the normal temperature before starting the expander, and the hot air can be discharged from the automatic valve box. This can shorten the precooling time of packing.
