US2011259044A1PendingUtilityA1

Method and apparatus for producing liquefied natural gas

37
Individually held — no corporate assignee on recordPriority: Apr 22, 2010Filed: Apr 22, 2010Published: Oct 27, 2011
Est. expiryApr 22, 2030(~3.7 yrs left)· nominal 20-yr term from priority
Inventors:Ned BaudatBill R. Minton
F25J 2205/66F25J 2210/40F25J 2220/66F25J 1/0022F25J 1/0221F25J 1/0251F25J 2205/60F25J 2220/68F25J 2210/42F25J 2205/24
37
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Claims

Abstract

Systems and methods for producing liquid natural gas from heat exchange with liquid nitrogen or air is provided. The produced liquid natural gas may be used as vehicle fuel. After heat exchange, the vaporized liquid nitrogen or air may be routed in the system to regenerate a heat exchange unit and/or a natural gas pretreatment unit. After assisting with the regeneration, the vaporized nitrogen or air may be safely vented to atmosphere. In one embodiment, a system for liquefying natural gas using a refrigerant includes a first treating unit configured to remove a contaminant from the natural gas; a first exchanger unit for liquefying the natural gas using the refrigerant; a second exchanger unit configured to receive the refrigerant from the first exchanger unit, wherein the first exchanger unit and the second exchanger unit operate on alternating cycles; a second treating unit configured to receive the refrigerant from the second exchanger unit; and a storage unit for the receiving the liquid natural gas.

Claims

exact text as granted — not AI-modified
1 . A method of liquefying natural gas, comprising:
 supplying a natural gas to a first pretreatment unit to remove a contaminant;   introducing the pretreated natural gas to a first heat exchange unit;   introducing a refrigerant to the first heat exchange unit;   liquefying the natural gas by absorbing heat from the refrigerant, thereby forming liquid natural gas;   vaporizing the refrigerant;   regenerating a second heat exchange unit using the vaporized refrigerant;   heating the vaporized refrigerant leaving the second heat exchange unit;   regenerating a second pretreatment unit using the heated refrigerant; and   collecting the liquid natural gas in a storage unit.   
     
     
         2 . The method of  claim 1 , further comprising dispensing the liquid natural gas in the storage unit to a vehicle. 
     
     
         3 . The method of  claim 1 , further comprising switching the second heat exchange unit to active operation after regeneration. 
     
     
         4 . The method of  claim 3 , further comprising regenerating the first heat exchange unit using refrigerant leaving the second heat exchange unit. 
     
     
         5 . The method of  claim 1 , wherein regenerating the second pretreatment unit includes discharging a hydrocarbon to a fuel storage unit. 
     
     
         6 . The method of  claim 5 , further comprising reducing a temperature of the heated refrigerant and flowing the reduced temperature refrigerant through the second pretreatment unit. 
     
     
         7 . The method of  claim 1 , further comprising removing contaminants from the natural gas as it flows through the first heat exchange unit. 
     
     
         8 . The method of  claim 7 , wherein removing the contaminants comprises freezing the contaminants. 
     
     
         9 . The method of  claim 8 , further comprising adhering the frozen contaminants to a surface of the first heat exchange unit. 
     
     
         10 . The method of  claim 9 , further comprising filtering the frozen contaminants from the natural gas. 
     
     
         11 . The method of  claim 1 , wherein the refrigerant is liquid nitrogen or air. 
     
     
         12 . A system for liquefying natural gas using a refrigerant, comprising:
 a first treating unit configured to remove a contaminant from the natural gas;   a first exchanger unit for liquefying the natural gas using the refrigerant;   a second exchanger unit configured to receive the refrigerant from the first exchanger unit, wherein the first exchanger unit and the second exchanger unit operate on alternating cycles;   a second treating unit configured to receive the refrigerant from the second exchanger unit; and   a storage unit for the receiving the liquid natural gas.   
     
     
         13 . The system of  claim 12 , wherein the first and second treating units operate on alternating cycles. 
     
     
         14 . The system of  claim 12 , wherein the first exchanger unit is configured to remove additional contaminants from the natural gas. 
     
     
         15 . The system of  claim 14 , wherein a temperature in the first exchanger unit is sufficient to freeze the additional contaminant. 
     
     
         16 . The system of  claim 12 , wherein system further comprises a filter unit. 
     
     
         17 . The system of  claim 12 , wherein the system further comprises a heating unit for heating the refrigerant. 
     
     
         18 . The system of  claim 17 , wherein fuel for the heating unit is supplied from a fuel storage unit that is in selectively fluid communication with the first and second treating units for replenishing fuel in the fuel storage unit. 
     
     
         19 . The system of  claim 12 , further comprising a dispensing unit connected to the storage unit for transfer of the liquid natural gas. 
     
     
         20 . The system of  claim 19 , further comprising a pump for transferring the liquid natural gas. 
     
     
         21 . The system of  claim 19 , wherein the liquid natural gas is transferred to a vehicle or a mobile storage unit. 
     
     
         22 . The system of  claim 12 , wherein the treating units include a molecular sieve to remove the contaminants. 
     
     
         23 . The system of  claim 12 , wherein the treating units include an amine unit to remove carbon dioxide. 
     
     
         24 . The system of  claim 23 , wherein the treating units further include a molecular sieve configured to dry the natural gas after treatment in the amine unit. 
     
     
         25 . The system of  claim 23 , wherein the treating units include a glycol dehydration unit. 
     
     
         26 . A method of liquefying a natural gas, comprising:
 introducing the natural gas to a first heat exchange unit;   introducing a refrigerant to the first heat exchange unit;   liquefying the natural gas by absorbing heat from the refrigerant, thereby forming liquid natural gas;   freezing a contaminant from the natural gas;   vaporizing the refrigerant;   regenerating a second heat exchange unit using the vaporized refrigerant;   venting the vaporized refrigerant;   utilizing the mixed contaminants and natural gas to provide power from a gas turbine generator; and   collecting the liquid natural gas in a storage unit.   
     
     
         27 . The method of  claim 26 , further comprising dispensing the liquid natural gas in the storage unit to a vehicle or to a liquid natural gas transporter. 
     
     
         28 . The method of  claim 26 , wherein regenerating the first heat exchange unit includes discharging a hydrocarbon and contaminants to a fuel storage unit. 
     
     
         29 . The method of  claim 26 , further comprising removing contaminants from the natural gas as it flows through the first heat exchange unit. 
     
     
         30 . The method of  claim 29 , wherein removing the contaminants comprises freezing the contaminants. 
     
     
         31 . The method of  claim 30 , further comprising adhering the frozen contaminants to a surface of the first heat exchange unit. 
     
     
         32 . A system for liquefying a gas using a refrigerant, comprising:
 a first exchanger unit for liquefying the gas and removing a contaminant using the refrigerant;   a second exchanger unit configured to receive the refrigerant from the first exchanger unit, wherein the first exchanger unit and the second exchanger unit operate on alternating cycles; and   a storage unit for the receiving the liquid gas.   
     
     
         33 . The system of  claim 32 , wherein the contaminant includes one of water, carbon dioxide, and combinations thereof. 
     
     
         34 . The system of  claim 33 , wherein a temperature in the first exchanger unit is sufficient to freeze the contaminant. 
     
     
         35 . The system of  claim 32 , wherein the system further comprises a gas turbine generator to produce power. 
     
     
         36 . The system of  claim 32 , wherein the gas contains at least 50 mole % of methane or ethane.

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