The liquid level of liquid oxygen in the main cooling system directly affects the balance of heat exchange area and cooling capacity, and the cooling capacity can be adjusted by adjusting the liquid level during operation. The main cooling relies on the liquid oxygen infiltration heat exchange plate bundle to complete the heat exchange, the liquid level is too low, the effective heat exchange area is reduced, the nitrogen condensation capacity of the lower tower is reduced, the reflux liquid of the upper and lower towers is reduced, and the distillation condition is deteriorated; When the liquid level is too high, the static pressure of liquid oxygen increases, the temperature difference of main cooling heat exchange decreases, and the heat exchange efficiency becomes worse.
Under normal working conditions, priority should be given to maintaining the liquid oxygen level of the main cooling system within the design range. If the cooling capacity of the system is surplus and the liquid level continues to rise, the liquid oxygen product withdrawal can be moderately increased to take away the excess cooling capacity and inhibit the continuous rise of the liquid level; It can also adjust the cooling capacity of the expander to prevent a large amount of liquid from accumulating.
When the cooling capacity of the unit is insufficient and the liquid level drops slowly, the recovery of liquid oxygen shall be reduced, and the cooling capacity shall be reduced to output, so as to retain the internal cooling capacity reserve of the unit; At the same time, optimize the working condition of the expander to improve the refrigeration capacity and gradually stabilize the liquid oxygen level.
During the adjustment, it is forbidden to increase or decrease the liquid oxygen extraction amount rapidly and substantially, so as to avoid the instability of the main cooling heat exchange caused by the violent fluctuation of the liquid level.
In addition, the liquid level adjustment can only balance the existing cooling capacity distribution, and cannot generate cooling capacity out of thin air. If the liquid level continues to fall and the adjustment of the produced capacity is invalid, it indicates that the total cooling capacity gap of the unit is large, and the cooling capacity of the expander must be increased synchronously.
