Abstract: Method and apparatus are disclosed for the recovery and removal of natural gas from a mine by liquefying and collecting the gas within the mine, and then transporting the liquified gas to the surface in a mobile tank. Natural gas is withdrawn from bore holes in a coal mine and liquefied using liquid nitrogen. A unique apparatus permits both the liquid nitrogen and the liquefied natural gas to be contained within a same insulated tank, enhancing the portable characteristics. Liquid nitrogen and its vapor are used to cool the natural gas so as to separate water and CO.sub.2. Means are disclosed for controlling the cooling by the cryogenic liquid by regulating the venting flow rate of its vapor in response to the pressure of the liquefied natural gas. The disclosed system eliminates the need for extensive piping and on-site pumping associated with conventional degasification processes.

Abstract: Method and apparatus are disclosed for the recovery and removal of natural gas from a mine by liquefying and collecting the gas within the mine, and then transporting the liquified gas to the surface in a mobile tank. Natural gas is withdrawn from bore holes in a coal mine and liquefied using liquid nitrogen. A unique apparatus permits both the liquid nitrogen and the liquefied natural gas to be contained within a same insulated tank, enhancing the portable characteristics. Liquid nitrogen and its vapor are used to cool the natural gas so as to separate water and CO.sub.2. Means are disclosed for controlling the cooling by the cryogenic liquid by regulating the venting flow rate of its vapor in response to the pressure of the liquefied natural gas. The disclosed system eliminates the need for extensive piping and on-site pumping associated with conventional degasification processes.

Abstract: This invention relates to a process for at least partially liquefying an air feedstream for subsequent separation into its components. The process comprises compressing an air feedstream, splitting the feedstream into at least a major portion, and a minor portion, partially cooling said major portion for delivery to a distillation or separation column, sufficiently cooling said minor portion for forming a critical fluid, isentropically expanding the thus formed critical fluid in a Pelton Wheel and then combining the minor portion and major portion for forming said air feedstream at a preselected pressure and temperature.

Abstract: This invention relates to an improved isentropic process for liquefying a gas, preferably a cryogenic fluid, which comprises forming a critical fluid, expanding the critical fluid through a Pelton Wheel to a pressure below the critical pressure forming a liquefied gas and removing work. The improvement for enhancing the efficiency of the Pelton Wheel in removing work comprises:withdrawing the liquefied gas from the Pelton Wheel at its saturation temperature or at a temperature below its saturation temperature, andestablishing and maintaining a vapor environment about the Pelton Wheel by the method selected from the group consisting of injecting a second gas into the Pelton Wheel, said second gas being introduced into the Pelton Wheel at the saturation temperature or at a temperature slightly above the saturation temperature of the liquefied gas; and raising the enthalpy of the liquefied gas after it has been withdrawn from the Pelton Wheel to an enthalpy above the enthalpy of saturated liquid.