The liquid air and liquid nitrogen in the lower column of the nitrogen maker are the raw material liquid provided to the upper column for rectification, so the rectification column is under the rectification column foundation. The proper control of liquid air nitrogen, liquid nitrogen purity is to ensure oxygen, nitrogen purity and output.

The nitrogen making machine has high purity of liquid and air, which can improve the purity of oxygen. High purity liquid nitrogen, large yield, nitrogen fertilizer to achieve the required purity purity. However, liquid-air purity and liquid nitrogen are mutually dependent. One improved purity, the other must be reduced purity. Moreover, liquid-air purity, liquid nitrogen and their respective output are also mutually restricted, increasing the purity, the flow rate will be reduced.

From the above limits, it can be seen that the purity and derived amount of nitrogen machine air liquid, liquid nitrogen has a balance point, so it is necessary to find a stable, careful.

The key point of operation in the tower is the opening of the throttle valve to control liquid nitrogen. Specifically, nitrogen and situation requirements for column rectification of liquid nitrogen purity is confidential, as much as possible to increase the amount of export. This provides a rectifying section reflux. The increase of reflux ratio can ensure the purity of nitrogen. At the same time, the reflux ratio of the tower will be reduced, and the purity of the liquid air will be improved, so that the purity of oxygen can be increased.

To what extent is the liquid nitrogen valve appropriate? This can be pure liquid nitrogen purity nitrogen by artificially judging the difference in normal circumstances, spraying liquid nitrogen and nitrogen purity tower equal to or slightly lower to allow liquid nitrogen, liquid nitrogen purity nitrogen purity less than 0.51% ~ 2%. The purity is low and the difference is large. The higher the purity, the worse. When the nitrogen purity is higher than 99.9%, it should equal the nitrogen purity of liquid nitrogen.

If the nitrogen machine liquid nitrogen purity is high, and the nitrogen purity is lower than the nitrogen purity is an abnormal phenomenon, indicating that the liquid nitrogen machine tower import number is too small, resulting in the liquid roof tower is not enough, the reflux ratio of the rectification section is not enough, can not improve the purity of nitrogen. At the same time, the tower will also be because the opening of the liquid nitrogen throttle is too small, the reflux ratio increases, the liquid air purity decreases, and the oxygen purity is further reduced, at this time, the nitrogen machine liquid nitrogen throttle valve opening must be increased. When liquid nitrogen purity, although decreased, but nitrogen purity can be increased.

The throttle valve in the liquid nitrogen throttle valve and the pure nitrogen process, the nitrogen machine is operated, usually with the nitrogen throttle valve in the waste liquid to control the liquid air purity, and the pure liquid nitrogen throttle valve in the nitrogen machine to control the liquid nitrogen purity.