Gas separation equipment for separating light hydrocarbons above ethane from natural gas. Natural gas deep cryogenic separation of light hydrocarbons equipment is in the liquid with liquid turbine expander technology after the success of the gradual replacement of the traditional refrigeration oil absorption method and developed. since the 70's, using this method of separation equipment has been widely used around the world. Figure 1 shows the working principle of a natural gas separation plant. The raw gas with pressure is passed through the separator (Ⅰ) to remove mechanical impurities and then into the adsorber to remove water, carbon dioxide and sulfides, and then cooled in the heat exchanger by the return cold gas stream. The hydrocarbons with higher boiling points condense down and the condensate is separated in the separator (Ⅱ). The liquid hydrocarbons are gasified and reheated by the heat exchanger and the cold is transferred to the forward flow feed gas and then into the middle of the methane tower. The gas obtained from the separation at the top of the separator (Ⅱ) enters the turbine expander for cooling, and then some hydrocarbon gas is condensed out. After expansion with liquid gas in the separator (Ⅲ) further separation of condensate and get a lower boiling point of liquid light hydrocarbons. Liquid light hydrocarbons enter the top of the methane tower and distill with the gas stream entering the middle of the tower to separate light hydrocarbons and methane, obtaining dry gas (methane) from the top of the methane tower and liquid hydrocarbons at the bottom of the tower. The methane gas and the dry gas coming out of the top of the separator (Ⅲ) converge and enter the heat exchanger to reheat, then the turbine expander blasting and pressurizing and then sent out.