A technology and a device for removing
hydrogen and
nitrogen from
methane-rich gas through rectification and producing
liquefied natural gas. The technology comprises two parts: low-temperature
liquefaction and rectification separation, wherein the low-temperature
liquefaction includes following steps: firstly feeding the
methane-rich gas containing
hydrogen and
nitrogen into a refrigerating box and liquefying a
methane component in the refrigerating box with a mixed
refrigerant for providing
cooling capacity; and the rectification separation includes: directly feeding the liquefied methane-rich gas containing
hydrogen and
nitrogen into a single rectifying column to perform rectification for removing the hydrogen, the nitrogen and a less amount of
carbon monoxide, wherein a gas mixture containing the hydrogen, the nitrogen and the less amount of the
carbon monoxide is obtained at the top of the rectifying column; passing the gas mixture through the refrigerating box for recycling the
cooling capacity and discharging the gas mixture out from the refrigerating box; and feeding back a
liquid phase at the bottom of the rectifying column to the refrigerating box for being supercooled and then discharging the
liquid phase out from the
system to obtain a
liquefied natural gas product which is not more than 500 ppm in the content of the hydrogen, is not more than 2% in the content of the nitrogen and is not more than 2% in the content of
carbon monoxide. The invention provides a technology in which
liquefied natural gas is produced by liquefying the methane-rich gas and meanwhile the hydrogen, the nitrogen and the carbon
monoxide are removed. The technology is simple in processes and is low in equipment
investment cost.