The expander is divided into pressurization end and expansion end. After emergency shutdown and planned shutdown, because the expansion end is in low temperature environment, it needs to continuously supply instrument gas and use lubricating oil for rewarming to normal temperature. Most instrument gas sources of low temperature separation device use centrifugal or screw type instrument air compressor for gas supply after shutdown, so that the dew point of gas source is low, When the expander needs to be started again, it is necessary to blow out the dew point of the pipe and nozzle at the expansion end. However, it is difficult to blow out the water in a short time, and the dew point at the outlet is difficult to reach the start-up standard of less than - 65 ℃ in a short time, It is time-consuming and laborious, which seriously affects the start-up time of the whole production system, but this method is used in most low-temperature separation production units.
