When the expansion machine leaks, the efficiency of the expansion machine will decrease. In this way, during normal operation, the pressure must be increased. Keep high pressure when starting, otherwise the starting time will be prolonged. Therefore, the air leakage of the expansion machine leads to the increase of power consumption, which must be eliminated in time.
The phenomena of air leakage of the expander include: the rising of exhaust temperature, the falling of liquid oxygen level, the rising of pressure in the lower tower, etc. In order to maintain that the liquid oxygen level does not drop, high pressure pressure should be increased. However, the above phenomenon may be caused by air leakage or other reasons. Therefore, further analysis and inspection are needed to determine whether the expansion machine leaks or not.
The method of checking air leakage of the expansion machine after heating is as follows:
Take the 50 m 3/h oxygen generator as an example, close the air throttle valve (section-1), the liquid-air throttle valve (section-2) and the liquid nitrogen throttle valve (section-3), and open the high pressure air inlet valve, make the high pressure rise slowly. Before pressurizing, open the neon he blow-off valve, and connect the blow-off valve to the test cup with a rubber hose, which contains water. If the high pressure leaks to the medium pressure, there will be bubbles bulging in the Cup, and whether the leakage or not will be known from the situation of bubbles bulging. Check whether the sealing surface of the air inlet valve of the expansion machine leaks or not, and turn the air inlet stem or tighten the spring to observe the change of air leakage. If there is no change after turning the valve, the air leakage is likely to be on the washer of the inlet valve sleeve. Check whether the sealing surface of the exhaust valve is leaking or not. When the vent needle of the exhaust oil pressure system is opened, pull the flywheel with manpower, and use the same method to check the inlet valve to observe whether there is any change in the air leakage, to help further judgment.
One important point of this inspection method is to make sure whether the section-1 Valve leaks. When the joint-1 valve is in the closed state, and the temperature in front of the throttle valve follows the outlet temperature of the expansion machine and decreases, it means that the joint-1 Valve leaks. When the section-1 Valve leaks, the valve rod can be used for checking to replace the valve needle, or the outlet valve of the expansion machine can be closed, and the air leakage situation can be judged according to the change of the exhaust pressure of the expansion machine.
If no air leakage phenomenon is found in the above inspection, it means that the air inlet valve and the gasket of its valve sleeve are sealed in good condition, then the next inspection can be carried out. Release the high pressure first, lift up the inlet valve stem, and then slowly boost the pressure. If there is air leakage phenomenon in the process of high pressure rising, the air leakage is likely to be the exhaust valve or piston. Then turn the stem again to judge the sealing condition of the exhaust valve. If there is still no air leakage, it means that the expansion machine has no air leakage.
When the inlet and exhaust valves are both in the closed position, check that there is no leakage, and the exhaust valve can be lifted up. Then such as flat, the description intake valve leakage and exhaust valve leakproof. Then turn the inlet valve rod again to judge the leakage of the inlet valve.
