| 摘要 |
PURPOSE:To reduce the cost of superhigh purity methane by a method wherein a liquid of high boiling point component is distillated by a first distillating device, the liquid is used for cooling a capacitor, and superhigh purity methane in a liquid state is recovered from the bottom of a second distillating device to receive fluid taken out from the first distillating device. CONSTITUTION:Liquefied natural gas is introduced to the lower part of a first distillating tower 10, where the gas is distillated and treated. In this case, the mixture liquid of methane and hydrocarbon having a boiling point higher than that of the methane is distillated to the bottom part of the first distillating tower 10. The liquid is first introduced to a capacitor 12 of a tenth distillating tower 10 while a pressure and temperature through a capacitor cooling passage 30. A part of the liquid is vaporized at the tenth distillating tower and the capacitor 12 is cooled by means of a vaporizing latent heat. This method liquefies a part of gas in the top part of the first distillating tower 10 and returns it as reflux to the tower. Remaining fluid (mixture fluid of nitrogen and methane) is introduced to a conveying passage 32, a part of the fluid is introduced to a liquefier 37 for liquefaction, and the liquefied fluid is stored as high purity methane in a product storage tank. |
