Improved high-pressure nitrogen and carbon dioxide switching method

The invention discloses an improved high-pressure nitrogen and carbon dioxide switching method, which comprises the following operation steps: (a) during start-up, closing a first hand valve on an ultrahigh-pressure carbon dioxide pipeline and a fourth hand valve on an auxiliary line, opening a second hand valve, a third hand valve and a switching valve, slowly opening a regulating valve to introduce gas slowly, and stopping regulation after the pressure of a pipeline at a gas feed end of an ultrahigh-pressure nitrogen conveying pipeline becomes the same as that of an output pipeline subjected to heat exchange by a heat exchanger; (b) in a work condition of switching ultrahigh-pressure carbon dioxide by a system, directly closing the switching valve, then slowly opening the first hand valve to introduce the ultrahigh-pressure carbon dioxide into the system, and closing the regulating valve to complete a switching process; and (c) when a carbon dioxide compressor is in a halt, directly opening ...