Compressor

• US 20080008602A1
• Filed: 01/13/2005
• Published: 01/10/2008
• Est. Priority Date: 01/16/2004
• Status: Abandoned Application

• Current Assignee: BOC Group BV (Linde Plc)
• Original Assignee: BOC Group BV (Linde Plc)
• Inventors: Gerstendoerfer, Helmut, Pozivil, Josef
• Application Number:
  US10/582,903
• Publication Number:
  US 20080008602A1
• Time in Patent Office: Days
• US Class Current: 417/243
• CPC Class Codes: B63J 2099/003 of cargo oil or fuel, or of boil-off gases, e.g. for propulsive purposes
• CPC Class Codes: F04D 29/5833 flow schemes and regulation thereto
• CPC Class Codes: F04D 29/5846 cooling by injection
• CPC Class Codes: F17C 13/025 having the pressure as the parameter
• CPC Class Codes: F17C 13/026 having the temperature as the parameter
• CPC Class Codes: F17C 2203/0391 by vacuum
• CPC Class Codes: F17C 2203/0617 with one layer
• CPC Class Codes: F17C 2221/033 Methane, e.g. natural gas, CNG, LNG, GNL, GNC, PLNG
• CPC Class Codes: F17C 2223/0161 cryogenic, e.g. LNG, GNL, PLNG
• CPC Class Codes: F17C 2223/033 Small pressure, e.g. for liquefied gas
• CPC Class Codes: F17C 2223/043 in the gas
• CPC Class Codes: F17C 2223/047 with a dip tube
• CPC Class Codes: F17C 2225/0123 gaseous, e.g. CNG, GNC
• CPC Class Codes: F17C 2225/035 High pressure, i.e. between 10 and 80 bars
• CPC Class Codes: F17C 2225/036 Very high pressure, i.e. above 80 bars
• CPC Class Codes: F17C 2227/0164 with specified compressor type, e.g. piston or impulsive type
• CPC Class Codes: F17C 2227/0185 comprising several pumps or compressors
• CPC Class Codes: F17C 2227/0306 using the same fluid
• CPC Class Codes: F17C 2227/0316 Water heating
• CPC Class Codes: F17C 2227/0339 using the same fluid
• CPC Class Codes: F17C 2227/0388 : separate
• CPC Class Codes: F17C 2227/0393 : using a vaporiser
• CPC Class Codes: F17C 2250/032 : using computers
• CPC Class Codes: F17C 2250/0408 : Level of content in the vessel
• CPC Class Codes: F17C 2250/043 : Pressure
• CPC Class Codes: F17C 2250/0439 : Temperature
• CPC Class Codes: F17C 2250/0631 : Temperature
• CPC Class Codes: F17C 2260/035 : of fluid
• CPC Class Codes: F17C 2265/015 : by separating
• CPC Class Codes: F17C 2265/022 : identical fluid
• CPC Class Codes: F17C 2265/033 : with cooling
• CPC Class Codes: F17C 2265/037 : with pressurising
• CPC Class Codes: F17C 2265/066 : for feeding engines for propulsion
• CPC Class Codes: F17C 2270/0105 : Ships
• CPC Class Codes: F17C 9/00 : Methods or apparatus for discharging liquefied or solidified gases from vessels not under pressure
• CPC Class Codes: F28F 27/02 : for controlling the distribution of heat-exchange media between different channels static flow control means in header boxes F28F9/026; arrangements of guide plates or guide vanes F28F9/22, F28F25/12
• CPC Class Codes: Y02T 70/50 : Measures to reduce greenhouse gas emissions related to the propulsion system

Abstract

A rotary liquefied natural gas boil-off compressor has a series of compression stages. A gas passage passes through the series of compression stages. The gas passage extends through and is in heat exchange relationship with cooling means in the form of indirect heat exchangers. Each of the heat exchangers is cooled by LNG supplied from a pipeline. Flow control valves are provided for controlling the flow of LNG to the heat exchangers respectively. The valves are controlled in response to temperature sensors respectively, so as to maintain the inlet temperature of each of the compression stages at a chosen sub-ambient temperature or between chosen sub-ambient temperature limits.

Claims

1. A rotary liquefied natural gas boil-off compressor having at least two compression stages in series, a gas passage passing through the series of compression stages, the gas passage extending through and being in heat exchange relationship with at least one cooling means between the or each pair of compression stages, characterised in that the cooling means or at least one of the cooling means is a cryogenic cooling means and in that there is valve means for controlling flow of cryogenic coolant into the cryogenic cooling means in response to the inlet temperature, or a related parameter, of the next compression stage downstream of the cryogenic cooling means so as, in use, to maintain said inlet temperature at a chosen sub-ambient temperature or between chosen sub-ambient temperature limits.

2. The compressor according to claim 1, characterised in that the cryogenic cooling means comprises an indirect cooling means.

3. The compressor according to claim 1, characterised in that the cryogenic cooling means comprises a direct cooling means.

4. The compressor according to claim 3, characterised in that the direct cooling means comprises a chamber having an inlet for the introduction of a cryogenic liquid.

5. The compressor according to claim 4, characterised in that the outlet of the direct cooling communicates with a vessel adapted to disengage particles of liquid from the natural gas, the vessel having an outlet for natural gas communicating with said next compression stage.

6. The compressor according to claim 1, characterised in that there is a cryogenic cooling means intermediate each pair of successive compression stages.

7. The compressor according to claim 1, characterised in that there are at least three compression stages in sequence and in that there is at least one direct cryogenic cooling means and at least one indirect cryogenic cooling means.

8. The compressor according to claim 7, characterised in that an inlet of a direct cooling means communicates with an outlet of an indirect cooling means.

9. The compressor according to claim 1, characterised in that there is a cryogenic cooling means downstream of the final compression stage.

10. The compressor according to claim 1, characterised in that there is a cryogenic cooling means upstream of the first compression stage.

11. The compressor according to claim 1, characterised in that the compressor has an intermediate inlet communicating with a forced liquefied natural gas vaporiser.

12. A liquefied natural gas storage tank having an outlet for boiled-off natural gas communicating with a compressor as claimed in claim 1, the said cryogenic cooling means communicating with the liquefied natural gas in the storage tank.

13. A method of operating a rotary liquefied natural gas boil-off compressor having at least two compression stages in series and a gas passage passing through the series of compression stages, the method comprising cooling the compressed boiled-off natural gas by means of a cryogenic coolant downstream of one of the compression stages and upstream of another, monitoring the inlet temperature, or a related parameter, of the compressed natural gas at the inlet to the other compression stage, and adjusting the flow rate of cryogenic coolant so as to maintain said inlet temperature at a chosen sub-ambient temperature or between chosen sub-ambient temperature limits.

14. The method according to claim 13, characterised in that the inlet temperature of each compression stage is maintained at a temperature in the range of minus 50 to minus 140°

C.

15. The method according to claim 14, characterised in that the pressure ratio across each compression stage is in the range 2.15:

1 to 3;

1.

16. The method according to claim 15, characterised in that the pressure ratio across each compression stage is in the range 2.5:

1 to 3;

1.