Cryocooler Suitable for Gas Liquefaction Applications, Gas Liquefaction System and Method Comprising the Same

Abstract

The present invention relates to a cryocooler suitable for gas liquefaction applications, that comprises a coldhead (1) with one or more refrigeration stages (2, 3); further comprising: a refrigerator compressor (4) for distributing compressed gas-phase cryogen inside the coldhead (1); a heat exchanging coil (9) arranged at least partially around the external region of the coldhead (1); at least one extraction orifice (8) communicating a gas circulation circuit (5) inside the coldhead (1) with the heat exchanging coil (9); acting said extraction orifice/s (8) as pass-through port/s which allow the gas inside the coldhead (1) to flow through the inside of the heat exchanger coil (9) for exchanging heat with the exterior thereof, and wherein the heat exchanging coil (9) is adapted to connect and redirect the gas to one return port (8′) connected to the gas circulation circuit (5). Another object of the invention relates to a cryogen-gas liquefaction system (11) and a method for liquefaction of gases that comprises said system (11).

1 . A cryocooler suitable for gas liquefaction applications, the cryocooler comprising:
 a coldhead with one or more refrigeration stages;   a refrigerator compressor for distributing compressed cryogen gas inside the coldhead, acting as refrigeration means for lowering the temperature of the refrigeration stages, wherein said cryogen gas is supplied to and returned from the coldhead through a gas circulation circuit comprising input and output gas lines, which connect the coldhead with the refrigerator compressor; and   at least one extraction orifice communicating the gas circulation circuit inside the coldhead with the external region of the refrigeration stages, acting as a pass-through port which allows the gas inside the coldhead to flow to the exterior thereof;   wherein the cryocooler further comprises a heat exchanging coil arranged at least partially around the external region of the coldhead, and wherein said heat exchanging coil is connected at one end to the gas circulation circuit through the extraction orifice, and at other end to one return port connected to said gas circulation circuit.   
     
     
         2 . The cryocooler of  claim 1 , wherein the return port is arranged at the coldhead. 
     
     
         3 . The cryocooler of  claim 1 , wherein the return port is arranged at the output gas line between the coldhead and the refrigerator compressor. 
     
     
         4 . The cryocooler of  claim 1 , further comprising a thermally insulating layer arranged between the heat exchanging coil and the external region of the coldhead. 
     
     
         5 . The cryocooler of  claim 1 , wherein the heat exchanging coil is connected to the extraction orifice and/or to the return port through one or more of the following elements: one or more cryogenic flow valves, a mass flow controller a control volume, a capillary tube, an insulating seal and/or or one or more joints. 
     
     
         6 . The cryocooler of  claim 1 , further comprising a PLC connected to the refrigerator compressor for controlling the pressure within the coldhead. 
     
     
         7 . The cryocooler of  claim 1 , wherein the cryogen gas within the refrigerator compressor is helium. 
     
     
         8 . A cryogen-gas liquefaction system comprising:
 the cryocooler of  claim 1 ;   a storage container comprising a liquid storage portion and a neck portion extending therefrom, the liquid storage portion being adapted to contain a liquefied gas bath at the bottom of the storage container and comprising a liquefaction region above said bath;   a gas pressure control mechanism for controlling the cryogen gas pressure within the liquefaction region of the storage container; and   a PLC connected to the gas refrigerator compressor, for controlling the pressure within the coldhead;   wherein the coldhead of the cryocooler is arranged at the neck portion of the storage container, so that the gas circulating through the inside of the heat exchanging coil can exchange heat with the gas stored at said neck portion, and wherein the heat exchanging coil is adapted to connect and redirect the gas from the gas circulation circuit through the extraction orifice to one return port connected to said gas circulation circuit.   
     
     
         9 . The cryogen-gas liquefaction system of  claim 8 , further comprising a gas source module containing an amount of gas-phase cryogen for its introduction into the liquefaction region of the storage container. 
     
     
         10 . The cryogen-gas liquefaction system of  claim 9 , wherein the gas source module contains high purity helium gas, recovered and/or purified from a helium-using equipment. 
     
     
         11 . The cryogen-gas liquefaction system of  claim 8 , further comprising a level meter for measuring the volume of liquid within the storage container, and/or a transfer port extending from the liquid storage portion to an external surface of the storage container. 
     
     
         12 . The cryogen-gas liquefaction system of  claim 8 , wherein the cryogen gas within the storage container and/or within the compressor is helium, nitrogen, oxygen, hydrogen or neon. 
     
     
         13 . A cryogen-gas liquefaction method for use in the cryogen-gas liquefaction system of  claim 8 , wherein the cryogen-gas liquefaction method comprises:
 (i) providing at least:
 a storage container having a liquefaction region and defined by a storage portion and a neck portion extending therefrom; 
 a pressure control mechanism for controlling the pressure within the liquefaction region of the storage container; and 
 a cryocooler coldhead at least partially disposed within the neck portion, the coldhead being adapted to condense a cryogen contained within the liquefaction region from a gas-phase to a liquid phase;
 wherein the cryocooler coldhead comprises:
 a refrigerator compressor for distributing cold compressed gas-phase cryogen inside the coldhead, wherein said cryogen is supplied to and returned from the coldhead and acts as refrigeration means for lowering the temperature of one or more refrigeration stages of the coldhead; 
 a heat exchanging coil arranged around the external region of the refrigeration stages of the coldhead; 
 one or more extraction orifices communicating a gas circulation circuit inside the coldhead with the heat exchanger coil, acting as pass-through ports which allow the gas inside the coldhead to flow through the inside of the heat exchanging coil for exchanging heat with the gas in the liquefaction region of the storage container; and wherein the heat exchanging coil is adapted to connect and redirect the gas to one return port connected to said gas circulation circuit; and 
 a PLC connected to the refrigerator compressor for controlling the pressure within the coldhead; 
 
 
   (ii) measuring and controlling the vapor pressure within said liquefaction region of the storage container with the pressure control mechanism and the PLC; and   (iii) maintaining the vapor pressure within said liquefaction region of the storage container by means of the pressure control mechanism.   
     
     
         14 . The cryogen-gas liquefaction method of  claim 13 , wherein step (i) further comprises measuring the internal pressure within the coldhead and step (ii) further comprises maintaining said pressure the coldhead with the PLC. 
     
     
         15 . The cryogen-gas liquefaction method of  claim 13 , further comprising the step of injecting gas into the liquefaction region of the storage container with a gas source module, in collaboration with the gas pressure controller for maintaining the vapor pressure during step (iii).