What is the working principle of the axial displacement indicator of the air compressor of the complete air separation plant?

In the actual operation of the complete air separation plant, the heat transfer area of the heat exchanger has been fixed. If the temperature difference at the hot end expands, it means that the cooling capacity of the reflux gas cannot be fully recovered in the heat exchanger. This may be due to the decrease in the heat transfer performance of the heat exchanger, and the heat that can be transferred under the same heat transfer area is reduced; it may also be caused by changes in airflow and airflow temperature. Specific analysis is required for different processes and different heat exchanger structures. The long-tube and short-tube condensing-evaporators of the complete set of air separation equipment are both tubular type. The copper tubes are arranged vertically in concentric circles or equilateral triangles. The upper and lower parts are equipped with brass tube sheets. The tubes and tube sheets are welded with tin. Weld firmly. The long tube type tube is liquid oxygen evaporation, and the short tube type tube is gas nitrogen condensation. The long tube is about 3m long.
The heat exchange conditions of the three sections of the complete set of air separation plants are different, and the heat exchange in the boiling section is the strongest. In order to obtain a relatively large boiling heat transfer coefficient (the surface heat transfer coefficient indicating the strength of the convective heat transfer capacity of the fluid, its unit is W/(m2•℃)), appropriate conditions must be selected to shorten the preheating section and the steam section. length, expand the length of the evaporation section. The complete set of air separation plant reduces the temperature after expansion. The lower the temperature after expansion, the greater the temperature difference with the forward air, and the stronger the heat transfer. Therefore, at this stage, the temperature after the expander should be controlled as low as possible without liquefaction, for example, around -180 to +185 °C.

Check the working quality of the liquefier, which can be judged by the difference between the temperature after the expander and the temperature of the dirty nitrogen leaving the liquefier. If the temperature rise is large, it means that the working condition is good; if the temperature rise is not obvious, it is possible that the liquefier is blocked and does not work. The complete set of air separation plant is equipped with three krypton towers in the rectification process. One krypton tower obtains lean krypton after rectification; At the same time of the concentration of krypton and xenon, the hydrocarbons contained in the oxygen are also concentrated in the lean krypton or crude krypton, so after the rectification of the one-krypton tower and the two-krypton tower, the hydrocarbons must be removed. The saturated liquid nitrogen drawn out is also at this temperature. The temperature of the liquid nitrogen is about 16°C higher than the temperature of the gas nitrogen in the upper tower. Therefore, when the two fluids flow through the liquid nitrogen subcooler, after heat exchange, the liquid nitrogen releases heat and is cooled into a subcooled liquid. Nitrogen becomes superheated vapor due to heat absorption.
In order to avoid the increase in the concentration of hydrocarbons in the liquid oxygen, according to the material balance, it is necessary to draw out a part of the liquid oxygen from the main cooler, and extract a part of the hydrocarbons from the main cooler. The minimum amount of liquid oxygen extracted is equivalent to 1% of the gas and oxygen production and then gasified separately. The rectification process is carried out through multiple trays, so that the argon fraction in the rising vapor is continuously increased, and the oxygen component in the reflux liquid is continuously increased. Crude argon is obtained at the top of the crude argon column and is mostly condensed to a liquid in the condenser evaporator. The oxygen shut-off valve with a diameter greater than 50mm should be equipped with an external bypass valve, and the valve diameter should be 25-40mm. When the oxygen pipeline is opened, first open the external bypass valve, and fill the pipeline or spherical tank with oxygen until the pressure before and after the valve is balanced (no flow), and then gradually open the oxygen valve until it is fully open.