Cng delivery system with cryocooler and method of supplying purified cng

Abstract

A fuel gas delivery system is provided. The fuel gas delivery system includes a feed line configured to provide a natural gas stream and a cryocooler fluidly coupled to the feed line. The cryocooler is configured to condense the natural gas to provide a liquefied natural gas (LNG) stream and to freeze impurities contained in the natural gas stream. The frozen impurities are separated from said LNG stream. A first heat exchanger is fluidly coupled to the cryocooler and the first heat exchanger is configured to vaporize at least a portion of the LNG stream to provide compressed natural gas. A delivery line is configured to supply the compressed natural gas to an end user and a removal line is configured to remove the impurities from the fuel gas delivery system.

What is claimed is: 
     
         1 . A fuel gas delivery system is disclosed comprising:
 a feed line configured to provide a natural gas stream;   a cryocooler fluidly coupled to said feed line, said cryocooler configured to condense the natural gas to provide a liquefied natural gas (LNG) stream and to freeze impurities contained in the natural gas stream, wherein the frozen impurities are separated from the LNG stream;   a first heat exchanger fluidly coupled to said cryocooler, said first heat exchanger configured to vaporize at least a portion of the LNG stream to provide compressed natural gas;   a delivery line configured to supply the compressed natural gas to an end user;   and a removal line configured to remove the frozen impurities from said fuel gas delivery system.   
     
     
         2 . The fuel gas delivery system of  claim 1 , wherein said system is configured to remove the frozen impurities during a regeneration mode, wherein during the regeneration mode, said system is depressurized and/or warmed to warm the impurities to at least one of a gas and a liquid for delivery to the removal line. 
     
     
         3 . The fuel gas delivery system of  claim 1 , further comprising a buffer tank fluidly coupled to said delivery line, wherein said buffer tank is configured to store the compressed natural gas at a pressure higher than a dispensing pressure and to supply compressed natural gas at said dispensing pressure. 
     
     
         4 . The fuel gas delivery system of  claim 1 , further comprising a regenerator fluidly coupled to said feed line and said delivery line, wherein said regenerator is configured to provide heat exchange between the natural gas stream and the LNG stream. 
     
     
         5 . The fuel gas delivery system of  claim 4 , further comprising a pump fluidly connected between said cryocooler and said regenerator, said pump configured to increase the LNG stream to a predetermined pressure. 
     
     
         6 . The fuel gas delivery system of  claim 1 , further comprising a first storage tank fluidly coupled to said cryocooler and configured to store LNG from said cryocooler. 
     
     
         7 . The fuel gas delivery system of  claim 6 , wherein said heat exchanger is thermally coupled to said first storage tank and configured to vaporize LNG within said first storage tank. 
     
     
         8 . The fuel gas delivery system of  claim 7 , further comprising a first valve operatively coupled to said feed line and a second valve operatively coupled to said delivery line, said first valve configured to prevent flow of LNG to said first storage tank when compressed natural gas in said first storage tank reaches a predetermined pressure, and said second valve configured to enable flow of the compressed natural gas to said delivery line when the compressed natural gas in said first storage tank reaches the predetermined pressure. 
     
     
         9 . The fuel gas delivery system of  claim 6 , further comprising a second storage tank fluidly coupled to said cryocooler and configured to store LNG from said cryocooler. 
     
     
         10 . The fuel gas delivery system of  claim 9 , further comprising a second heat exchanger thermally coupled to said second storage tank and configured to vaporize LNG within said second storage tank, wherein said first heat exchanger is thermally coupled to said first storage tank and configured to vaporize LNG within said first storage tank. 
     
     
         11 . The fuel gas delivery system of  claim 10 , wherein said first and second heat exchangers are fluidly coupled to said feed line, each of said first and second heat exchangers configured to receive and precool the natural gas stream by vaporizing the LNG stored in one of said first and second storage tanks. 
     
     
         12 . The fuel gas delivery system of  claim 10 , further comprising a switching valve operatively coupled downstream of said cryocooler, said switching valve configured to selectively direct the LNG stream to one of said first and second storage tanks. 
     
     
         13 . The fuel gas delivery system of  claim 11 , further comprising a switching valve operatively coupled to said feed line, said switching valve configured to selectively direct the natural gas stream to one of said first and second heat exchangers. 
     
     
         14 . The fuel gas delivery system of  claim 10 , further comprising first and second valves operatively coupled to said delivery line, wherein said first and second valves are configured to enable flow of the compressed natural gas to said delivery line, respectively, when the compressed natural gas in said first and second storage tanks reaches a predetermined pressure. 
     
     
         15 . The fuel gas delivery system of  claim 1 , wherein the impurities comprises water. 
     
     
         16 . A fuel gas delivery system comprising:
 a feed line configured to provide a natural gas stream;   a cryocooler fluidly coupled to said feed line, said cryocooler configured to cool said natural gas below the freezing point of impurities contained in said natural gas stream to separate the frozen impurities from a cooled and densified natural gas stream;   a first heat exchanger fluidly coupled to said cryocooler, said first heat exchanger configured to heat and pressurize at least a portion of the cooled and densified stream to provide compressed natural gas;   a delivery line configured to supply the compressed natural gas to an end user; and   a removal line configured to remove the frozen impurities from said fuel delivery system.   
     
     
         17 . The fuel gas delivery system of  claim 16 , further comprising a storage tank fluidly coupled to said cryocooler and configured to store the cooled and densified natural gas stream from said cryocooler, said storage tank including an adsorbent material configured to adsorb the cooled and densified natural gas stream removed of said impurities, wherein said first heat exchanger is thermally coupled to said storage tank. 
     
     
         18 . The fuel gas delivery system of  claim 17 , wherein said adsorbent material is a carbon adsorbent material. 
     
     
         19 . The fuel gas delivery system of  claim 17 , further comprising a first valve operatively coupled to said feed line and a second valve operatively coupled to said delivery line, said first valve configured to prevent flow of the cooled and condensed natural gas stream to said storage tank when compressed natural gas in said first storage tank reaches a predetermined pressure, and said second valve configured to enable flow of the compressed natural gas to said delivery line when said compressed natural gas in said first storage tank reaches the predetermined pressure. 
     
     
         20 . A method of supplying purified compressed fuel gas, the method comprising:
 supplying a natural gas stream to a cryocooler of a compressed natural gas delivery system;   freezing impurities contained in the natural gas stream;   condensing the natural gas to provide a liquefied natural gas (LNG) stream;   separating the frozen impurities from the LNG stream;   vaporizing the LNG stream to provide a compressed natural gas stream at a predetermined pressure; and   supplying the compressed natural gas to a delivery line.   
     
     
         21 . The method of  claim 20 , further comprising depressurizing and warming at least a portion of the gas delivery system to warm the separated impurities, and extracting the warmed impurities from the fuel delivery system. 
     
     
         22 . The method of  claim 21 , further comprising precooling the natural gas stream against the LNG stream prior to condensing in the cryocooler, wherein the LNG stream is vaporized. 
     
     
         23 . The method of  claim 21 , further comprising delivering the LNG stream to a first storage tank, wherein the LNG is vaporized in the first storage tank. 
     
     
         24 . The method of  claim 23 , further comprising opening a first valve when the compressed natural gas in the first storage tank reaches a predetermined pressure to supply the compressed natural gas to the delivery line, and closing a second valve when the compressed natural gas reaches the predetermined pressure to prevent flow of the LNG stream to the first storage tank. 
     
     
         25 . The method of clam  23 , further comprising delivering the LNG to a second storage tank, and precooling the natural gas stream against LNG in one of the first and second storage tanks by selectively supplying the natural gas stream to one of the first and second storage tanks, wherein the LNG is vaporized in one of the first and second storage tanks. 
     
     
         26 . The method of  claim 24 , further comprising precooling the natural gas stream against the first storage tank filled with LNG while LNG is supplied to the second storage tank to fill the second storage tank with LNG. 
     
     
         27 . A method of delivering a high purity compressed fuel gas, the method comprising:
 supplying a natural gas stream to a cryocooler of a compressed fuel gas delivery system;   cooling the natural gas in the cryocooler to a temperature below the freezing point of impurities contained in the natural gas stream;   separating the frozen impurities from the condensed natural gas to provide a cooled and densified natural gas stream;   pressurizing the cooled and densified stream to provide a compressed natural gas stream at a predetermined pressure; and   delivering the compressed natural gas to a delivery line.   
     
     
         28 . The method of  claim 27 , further comprising depressurizing and warming at least a portion of the fuel gas delivery system to warm the frozen impurities to a liquid or gas, and extracting the warmed impurities from the fuel delivery system. 
     
     
         29 . The method of  claim 27 , further comprising supplying the cooled and densified natural gas stream to a storage tank and adsorbing the cooled and densified natural gas stream in an adsorbent material contained in the storage tank. 
     
     
         30 . The method of  claim 29 , wherein the adsorbent material is at least one of a carbon adsorbent material and metal organic frameworks. 
     
     
         31 . The method of  claim 29 , further comprising opening a first valve when the compressed natural gas in the first storage tank reaches a predetermined pressure to supply the compressed natural gas to the delivery line, and closing a second valve when the compressed natural gas reaches the predetermined pressure to prevent flow of the cooled and densified stream to the storage tank. 
     
     
         32 . A method of removing impurities from a fuel gas stream in a fuel gas delivery system, the method comprising:
 supplying a natural gas stream to a cryocooler of the fuel delivery system, the cryocooler configured to condense the natural gas to a liquefied natural gas (LNG) stream and freeze impurities contained in the natural gas;   separating the impurities from the LNG stream;   selectively supplying the LNG stream to one of a first storage tank and a second storage tank;   selectively precooling the natural gas stream against LNG in the first storage tank when the first storage tank is filled with a predetermined amount of LNG, wherein the LNG is vaporized into compressed natural gas;   selectively precooling the natural gas stream against the LNG in the second storage tank when the second storage tank is filled with a predetermined amount of LNG, wherein the LNG is vaporized into compressed natural gas;   opening a first valve when the compressed natural gas in the first tank is at a predetermined pressure to supply the compressed natural gas to a delivery line, and opening a second valve when the compressed natural gas in the second tank is at the predetermined pressure to supply the compressed natural gas to the delivery line; and   wherein LNG is vaporized in the first tank while the second tank is being filled with LNG from the cryocooler and LNG is vaporized in the second tank while the first tank is being filled with LNG from the cryocooler to provide a steady supply of compressed natural gas to the delivery line.