The two-position four-way valve of the nitrogen compressor is set to simplify the operation. It is a two-position four-way plunger valve. When the liquid phase of the tank truck is unloaded to the storage tank, because the liquid outlet of the tank truck is at a certain height from the bottom of the tank, the tank truck cannot be in a horizontal state when it is parked. A considerable amount of liquid and liquid will be stored in the tank truck tank. A full tank of high-pressure gas cannot be unloaded. This will bring economic losses to users. It also brings difficulties to the next loading. Therefore, the gas and liquid in the tank must be recovered. The handle of the four-way valve is in a horizontal position. The gas enters the unit through the lower flange of the four-way valve, and is discharged from the upper flange after compression; the handle of the four-way valve is vertically downward, and the gas enters the unit from the upper flange. After compression, It is discharged from the lower flange.
During the unloading operation of the nitrogen compressor, open the gas phase valve and the liquid phase valve so that the handle of the two-position four-way valve is in the normal position to start the propylene compressor. At this time, the compressor sucks the gas phase in the storage tank and reduces its pressure, while the pressure of the gas phase in the tank truck increases. Due to the pressure difference, the liquid in the tank truck tank is pressed into the storage tank through the liquid phase pipe until Until the liquid in the tank truck has been delivered. As mentioned above, there is still a certain amount of liquid in the tank of the tanker at this time and the full tank with pressurized gas cannot be unloaded. These liquids and gases must be recovered.
Because this machine is equipped with a two-position four-way valve, the operation of the recovery operation becomes extremely simple. As long as the valve on the liquid phase pipeline is closed, the handle of the two-position four-way valve is turned 90 degrees, that is, the normal position is changed to the reverse position. When the gas phase in the tanker tank is sucked by the compressor, the pressure will decrease, and the remaining liquid will continue to vaporize until all the liquid and gas in the tanker tank are recovered, so that the tanker tank maintains about 0.2MPa (Gauge pressure) residual pressure, recovery operation is over, stop.
When the propylene compressor is unloaded, the handle of the two-position four-way valve is horizontal, and the gas enters the unit through the lower flange port of the four-way valve. After being compressed, it is discharged from the upper flange port, that is, low inlet and high outlet; , The handle is vertically downward, the gas enters the unit through the upper flange port, and is discharged from the lower flange port after compression, that is, high inlet and low outlet.
In any case, the handle of the two-position four-way valve is not allowed to be in an inclined position, otherwise it will block the intake and exhaust passages of the propylene compressor.
During the recovery operation, do not make the maximum pressure ratio of the propylene compressor exceed 6, and do not make the pressure in the recovered tank lower than 0.18 MPa (gauge pressure).