What to do if the liquid oxygen pump stops suddenly: 1. Start the backup pump automatically; 2. The backup pump will not start

If both oxygen pumps fail~~ the main task is to keep the expander and the booster running, while also working quickly to restore the oxygen pumps; the sooner they are repaired, the better~~

If the backup pump can start, there’s no major problem; the pump that has stopped working should be brought back online as soon as possible, and once the issue is resolved, it should be set to be ready for use at any time. If the backup pump does not start, and given that the operating conditions vary from plant to plant, if the liquid oxygen after passing through the pump is sent to a heat exchanger where it is converted into gaseous oxygen before being supplied to the customer, then the cessation of pump operation results in a reduction in the cooling capacity available for the heat exchanger. This leads to a sudden increase in the pressure at the compressor outlet, causing the compressor to shut down due to high pressure and ultimately resulting in the shutdown of the entire equipment. At this point, the expander guide vanes should be opened wider to reduce the production of liquid nitrogen, in order to achieve a temporary balance of cooling capacity; however, if the oxygen pump cannot be started for an extended period, the system will eventually stop operating.

What about adjusting the main tower’s operating conditions? The high-pressure air throttling path is gone, resulting in changes in the distillation process in the lower tower. . . How to adjust

Have you done it in practice? It seems that with this approach, the expansion rate could become too high; at the same time, the shaft temperatures at both ends might also be very high~~

Which one does the compressor outlet refer to? The booster pump? Two-stage venting for pressure reduction is possible; as for the expander, in order to maintain the temperature before the machine, there is no flow path for the booster. How then should operations in the lower tower be carried out?

Reduce the unit’s load; pay attention to the expander and adjust the heat exchanger

Quickly adjust the plate heat exchanger temperature to prevent overpressure; reduce the flow of hot air corresponding to it, so that the pressure in stages two and three of the unit drops rapidly.

Depending on the circumstances, the load on the second stage of the booster should be reduced first; the criterion for this is to maintain an appropriate temperature difference in the high-pressure heat exchanger, that is, the temperature at the inlet of the expander, so as to control its speed and prevent it from stopping or losing load. Meanwhile, the loads on the first stage and the air compressor should also be adjusted accordingly. Once stability is achieved, the cause of the problem should be identified and resolved, after which the oxygen pump can be started to operate the second stage and production can resume! It can be handled without stopping the vehicle!

This situation has been encountered in practice: when the liquid oxygen pump stops operating, in addition to reducing the amount of liquid nitrogen drawn and by increasing the turbine guide vanes, it is also necessary to reduce the air intake to the compressor, thereby decreasing the production of liquid oxygen. The main coolant level in the main tower rises rapidly, so a discharge valve is needed to release liquid oxygen. During operation, the expander did not experience overspeed, but since the equipment and operating conditions vary from factory to factory, it cannot be generalized.