Regasification system and method

1. A method for regasification of liquid natural gas (LNG) aboard a floating carrier vessel before the LNG is offloaded as a gas, said method comprising:

boosting the LNG pressure and flowing said LNG into an LNG/coolant heat exchanger ( 230 ) in which the LNG is evaporated;

flowing evaporated natural gas (NG) into an NG/steam heat exchanger ( 120 ), in which the NG is heated before the NG is transferred to shore as superheated vapor;

evaporating the LNG in said LNG/coolant heat exchanger ( 230 ) by thermal exchange against a coolant entering said heat exchanger as a gas and leaving said heat exchanger in a liquefied state; and

flowing said coolant in a closed coolant circuit including a valve ( 225 ), and through at least one coolant/seawater heat exchanger ( 220 a , 220 b ) in which the liquefied coolant is evaporated before entering the LNG/coolant heat exchanger, and wherein the pressure in the evaporated coolant is controlled by the valve ( 225 ).

2. A method for regasification of liquid natural gas (LNG) aboard a floating carrier vessel before the LNG is offloaded as a natural gas, said method comprising:

boosting the LNG pressure and flowing said LNG into an LNG/coolant heat exchanger ( 230 ) in which the LNG is evaporated;

flowing evaporated natural gas (NG) into an NG/steam heat exchanger ( 120 ), in which the NG is heated before the NG is transferred to shore as superheated vapor;

evaporating the LNG in said LNG coolant heat exchanger ( 23 O) by thermal exchange against a coolant entering said heat exchanger as a gas and leaving said heat exchanger in a liquefied state; and

flowing said coolant in a closed coolant circuit and through at least one coolant/seawater heat exchanger ( 220 a , 220 b ) in which the liquefied coolant is evaporated before entering the LNG/coolant heat exchanged wherein the pressure in the evaporated coolant is controlled by a valve ( 225 ) and wherein said coolant temperature is controlled by means of a bypass ( 231 , 232 , 233 ) on said LNG/coolant heat exchanger.

3. The method of claim 1 , wherein the number of at least one coolant/seawater heat exchangers is two.

4. The method of claim 1 , wherein the coolant is propane.

5. The method of claim 1 , wherein the coolant is a medium having a boiling temperature of 0° C. at any pressures between 2 bar and 25 bar.

6. The method of claim 1 , wherein the LNG/coolant heat exchanger is a stainless steel compact printed circuit heat exchanger (PCHE).

7. The method of claim 1 , wherein the NG/steam heat exchanger is an SS316 shell and tube heat exchanger.

8. The method or claim 1 , wherein the at least one coolant/seawater heat exchanger is at least one titanium plate heat exchanger.

9. The method of claim 1 , wherein the coolant is flowed through said circuit by a pumping means ( 210 ).

10. A liquid natural gas (LNG) regasification system for installation aboard a floating carrier vessel, said system comprising:

an LNG/coolant heat exchanger ( 230 ) for evaporation of the LNG;

a booster pump ( 110 ) for boosting the pressure in the LNG prior to entering the LNG/coolant heat exchanger ( 230 );

a natural gas (NG)/steam heat exchanger ( 120 ) for heating the NG before the NG is transferred to shore as superheated vapor; and

at least one closed coolant circuit comprising at least one coolant/seawater heat exchanger ( 220 a , 220 b ) for evaporation of the liquefied coolant before said coolant is flowed into the LNG/coolant heat exchanger ( 230 ), said closed coolant circuit further comprising a valve ( 225 ) for controlling the pressure in the evaporated coolant, whereby the coolant evaporation temperature may be controlled.

11. The regasification system of claim 10 , wherein the at least one coolant circuit comprises at least two coolant/seawater heat exchangers ( 220 a , 220 b ).

12. The regasification system of claim 10 , wherein said coolant temperature is controlled by means of a bypass ( 231 , 232 , 233 ) on said LNG/coolant heat exchanger.

13. The regasification system of claim 10 , wherein the coolant is propane.

14. The regasification system of claim 10 , wherein the coolant is a medium having a boiling temperature of 0° C. at any pressures between 2 bar and 25 bar.

15. The regasification system of claim 10 , wherein the LNG/coolant heat exchanger is a stainless steel compact printed circuit heat exchanger (PCHE).

16. The regasification system of claim 10 , wherein the NG/steam heat exchanger is an SS316 shell an tube heat exchanger.

17. The regasification system of claim 10 , wherein the at least one coolant/seawater heat exchanger is at least one titanium plate heat exchanger.

18. The regasification system of claim 10 , wherein the coolant is flowed through said circuit by a pumping means ( 210 ).

19. A method for regasification of liquid natural gas (LNG) aboard a floating carrier vessel before the LNG is offloaded as a gas, the method comprising:

boosting the LNG pressure and flowing the LNG into an LNG/coolant heat exchanger in which the LNG is evaporated;

flowing evaporated natural gas (NG) into an NG/steam heat exchanger, in which the NG is heated before the NG is transferred to shore as superheated vapor;

evaporating the LNG in the LNG/coolant heat exchanger by thermal exchange against a coolant entering the heat exchanger as gas and leaving the heat exchange in a liquefied state; and

flowing the coolant in a closed coolant circuit and through at least one coolant/seawater heat exchanger in which the liquefied coolant is evaporated before entering the LNG/coolant heat exchanger, wherein the coolant circuit comprises a valve for controlling the pressure in the evaporated coolant.

20. A method for regasification of liquid natural gas (LNG) aboard a floating carrier vessel before the LNG is offloaded as a gas, the method comprising:

boosting the LNG pressure and flowing the LNG into an LNG/coolant heat exchanger in which the LNG is evaporated;

flowing evaporated natural gas (NG) into an NG/steam heat exchanger, in which the NG is heated before the NG is transferred to shore as superheated vapor;

evaporating the LNG in the LNG/coolant heat exchanger by thermal exchange against a coolant entering the heat exchanger as gas and leaving the heat exchanger in a liquefied state;

flowing the coolant in a closed coolant circuit and through at least one coolant/seawater heat exchanger in which the liquefied coolant is evaporated before entering the LNG/coolant heat exchanger; and

controlling the coolant temperature by means of a bypass on the LNG/coolant heat exchanger.

21. A liquid natural gas (LNG) regasification system for installation aboard a floating carrier vessel, the system comprising:

an LNG/coolant heat exchanger for evaporation of the LNG;

a booster pump for boosting the pressure in the LNG prior to entering the LNG/coolant heat exchanger;

a natural gas (NG)/steam heat exchanger for heating the NG before the NG is transferred to shore as superheated vapor; and a closed coolant circuit including:

at least one coolant/seawater heat exchanger for evaporation of the liquefied coolant before the coolant is flowed into the LNG/coolant heat exchanger; and

a valve for controlling the pressure in the evaporated coolant, whereby the coolant evaporation temperature may be controlled.

22. A liquid natural gas (LNG) regasification system for installation aboard a floating carrier vessel, the system comprising:

an LNG/coolant heat exchanger, including a bypass, for evaporation of the LNG;

a booster pump for boosting the pressure in the LNG prior to entering the LNG/coolant heat exchanger;

a natural gas (NG)/steam heat exchanger for heating the NG before the NG is transferred to shore as superheated vapor; and

a closed coolant circuit comprising at least one coolant/seawater heat exchanger for evaporation of the liquefied coolant before the coolant is flowed into the LNG/coolant heat exchanger;

wherein the coolant temperature is controlled by means of the bypass on the LNG/coolant heat exchanger.