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Publication numberUS3885394 A
Publication typeGrant
Publication dateMay 27, 1975
Filing dateDec 10, 1973
Priority dateDec 11, 1972
Also published asCA985159A, CA985159A1, DE2307390A1, DE2307390B2
Publication numberUS 3885394 A, US 3885394A, US-A-3885394, US3885394 A, US3885394A
InventorsKarel Witt, Christian Trepp
Original AssigneeSulzer Ag
Export CitationBiBTeX, EndNote, RefMan
External Links: USPTO, USPTO Assignment, Espacenet
Process and apparatus for treating and utilizing vaporized gas in a ship for transporting liquified gas
US 3885394 A
Abstract
The vaporized gas is first heated and then compressed. Thereafter, the gas is divided into two component flows with one component flow being sent to the ship's propulsion plant as a source of fuel. The second component flow is then further compressed and cooled in heat exchange relation with the continued flow of vaporized gas from the gas tanks. The cooled gas is then liquified and returned to the gas tanks.
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United States Patent 11 1 1111 3,885,394 Witt et al. May 27, 1975 PROCESS AND APPARATUS FOR 2,940,268 6/l960 Morrison 62/240 x TREATING AND UTILIZING VAPORIZED 3,229,473 H1966 Schumacher et al. 62/240 X GAS IN A FOR TRANSPORTING 3,303,660 2/1967 Berg 62/51 3,383,881 5/1968 Bailey 62/50 x LIQUIFIED GAS 3,768,271 10/1973 Denis 02 55 Inventors: Karel Witt, Volketswil; Christian Trepp, Winterthur, both of Switzerland Sulzer Brothers Ltd., Winterthur, Switzerland Filed: Dec. 10, 1973 Appl. NO.Z 423,122

Assignee:

Foreign Application Priority Data Dec. ll, 1972 Switzerland l7958/72 U.S. Cl. 60/651; 60/671; 62/7; 62/54; 62/240 Int. Cl. Ftllk 25/08 Field of Search 114/74 A; 62/7, 50, 51, 62/54, 240; 60/651, 67]

References Cited UNITED STATES PATENTS Sattler et a]. 62/7 PROPULSION UNIT Primary Examiner-Meyer Perlin Assistant ExaminerRonald C. Capossela Attorney, Agent, or Firm-Kenyon & Kenyon Reilly Carr & Chapin [57] ABSTRACT The vaporized gas is first heated and then compressed. Thereafter, the gas is divided into two component flows with one component flow being sent to the ships propulsion plant as a source of fuel. The second component flow is then further compressed and cooled in heat exchange relation with the continued flow of vaporized gas from the gas tanks. The cooled gas is then liquified and returned to the gas tanks.

9 Claims, 1 Drawing Figure PROCESS AND APPARATUS FOR TREATING AND UTILIZING VAPORIZED GAS IN A SHIP FOR TRANSPORTING LIQUIFIED GAS This invention relates to a process and apparatus for treating and utilizing vaporized gas from a liquified gas tank of a ship for transporting liquified combustible gas.

As is known, the liquified gas transported in tankers and ships vaporizcs or evaporates to some extent during travel due to the presence of heat even in the best insulated vessels. In order to accept this fact, proposals have been made to burn these gaseous products as fuel in a combustion device forming a part of the propulsion unit of the ship.

However, it has been found that the quantity of gas required to power the propulsion unit of a ship of normal size at normal speeds is less than the quantity of gas arising from vaporization.

Accordingly, it is an object of the invention to pro vide a proces and apparatus which can economically reduce vaporization losses by re-liquifying some of the gases.

It is another object of the invention to use the heat which is drawn off during re-liquifaction to heat the gas vaporized in the liquified gas tanks before this gas is compressed to a pressure suitable for the propulsion unit.

It is another object of the invention to re-liquify some of the boil-off or vaporized gas from a liquified gas tank in order to reduce the economic loss due to vaporization of the liquified gas cargo.

Briefly, the invention provides a process in which a flow of vaporized gas is drawn off at least one tank, compressed and divided into two component flows. One component flow is then fed as a fuel to the propulsion unit of a ship, for example, to a combustion device such as a piston engine, marine boiler or gas turbine plant. The other component flow is further compressed and passed in heat exchange relation with the continued flow of vaporized gas from the tank to heat the flow of vaporized gas prior to initial compression and to cool the gas component flow. The cooled gas component flow is then reduced in pressure and fed back to the gas tank in at least partly liquified form. In this way, it is possible to use the low temperature of the full gas flow drawn off the tanks to cool the second gas component flow over the entire temperature range covered during cooling and, at least, partial liquifaction of this component flow.

The invention also provides an apparatus which includes means for drawing off the flow of vaporized gas from a gas tank. a first compressor to compress the full flow and a first branch line to deliver one component flow to the propulsion unit. Also. a second compressor is used to receive and compress the second component flow and a heat exchanger is used to effect the heat exchange between the full flow and the second component flow. A pressure reducing means is also connected to the heat exchanger and the tank to deliver the at least partly liquified gas back to the tank.

Due to the compression of the full flow in the first compressor. the second compressor does not need to operate at low suction temperatures but instead can operate at temperatures above C.

These and other objects and advantages of the invention will become more apparent from the following detailed description and appended claims taken in conjunction with the accompanying drawing in which:

The drawing illustrates a schematic view of a ship employing an apparatus according to the invention.

Referring to the drawing, a ship such as a liquified combustible gas tanker has a propulsion unit (not shown) and a plurality of liquified gas tanks 10, only two of which are shown for simplicity. A means. such as a line 11, is connected to each tank 10 to draw off a flow of gas. for example. methane or natural gas vaporized in each at a temperature, for example, of l50C and approximately at atmospheric pressure. The line II is connected to a cooling passage 12 in a heat exchanger 13 to deliver the flow of vaporized gas to the passage 12 for heating, for example. to 10C in a manner as described below. A line 14 extends from the exit end of the passage 12 to a compressor 15 to deliver the heated flow for compression purposes. A delivery line 16 extends from the compressor 15 through an aftercooler 17 and divides into two branch lines l8, 19. One line 18 conveys one component flow of the gas after cooling in the aftercooler 17 to a combustion device (not shown) of the propulsion unit (not shown), e.g. a combustion chamber of a steam generator. The line 18 is provided with a non-return valve 20 and a pressure regulating valve 21 which maintains the pressure in the line 18 at a predetermined value by means of a controller 21a.

The compressor 15 has a drive motor 22 whose speed is controlled by a controller 23 according to the pressure in the line 11. The conditions are such that when the pressure rises in the line 11 due to the vaporization of gas in the tanks 10 the speed is increased and vice versa.

The branch line 19 carries a second gas component flow into a second compressor 24 formed by a threestage piston machine driven by a diagrammatically indicated electric motor 25. Coolers 26 are also provided between the various stages and where the gas component flow leaves the last stage.

A line 27 connects the outflow of the compressor 24 to the heat exchanger 13 so that the component flow of compressed gas comes into heat exchange relation with the continued flow of vaporized gas from the tanks 10 and is cooled. A pressure reducing means including a line 28 and a pressure reducing valve 29 e.g. an expansion valve is connected to the heat exchanger 13 to receive the cooled component flow. The pressure reducing valve 29 is operated by a controller 30 so as to maintain the desired pressure in the line 28. As shown, the valve 29 communicates via a line 31 with a separator 33 which has a conventional level regulating means 34 for operating a valve 35 in an exit line 36 to a pump 46. The pump 46 serves to feed the liquified gas back to the tanks 10.

The separator 33 is connected by a line 41 to another cooling passage 42 in the heat exchanger 13 so that volatile gas constituents, particularly nitrogen, can be drawn off along the line 41 and used to cool the gas component flow passing through the heat exchanger during liquification. These constituents then flow along a line 43 into the line 18, where they are added to the component intended for combustion.

As shown, the aftercooler 17 is connected by a line 38 to a source of coolant, for example, cooling water for cooling the gas flow through the line 16. Also, a regulating valve 380 is disposed in the line 38 and is operated via a controller 39 in accordance with temperature variations in the compressed gas in the line 16 so that a rise in temperature is followed by increased cool ing and vice versa.

The process of treating and utilizing the vaporized gas resides in drawing off the gas from the tanks via the line 11 into the heat exchanger 13. After heating, for example, to 10C, the gas flows along the line 14 into the compressor 15 and is compressed to a pressure of approximately 2 atmospheres absolute and heated to about 60C. After cooling to about 40C in the aftercooler 17, one component flow of gas is conveyed via the line 18 at the same pressure to the furnace (not shown) of a steam generator which produces steam for the turbines which propel the ship.

The other gas component flow passes via the line 19 into the compressor 24 and is compressed, for example, to about 42 atmospheres absolute and at a temperature of, for example, 40C. The gas then flows along the line 27 into the zone of the heat exchanger containing the cooling passage 12 and is cooled, for example, to 120C. The gas so cooled is discharged from the heat exchanger 13 along the line 28 to the pressure reducing valve 29, where the pressure is reduced to 2 atmospheres absolute, that is, to the delivery pressure of the first compressor 15.

From the pressure reducing valve 29, the gas, now at least partly liquified, flows along the line 31 into the separator 33 and collects in the lower part of the separator 33. The re-liquified portion of the gas is then re turned to the tanks 10 via the line 36 by means of the pump 46.

This invention is not restricted to the embodiment illustrated. On the contrary, the gas component flow intended for combustion, instead of going to a boiler furnace, can be fed to a diesel engine at a pressure of, for example, eight atmospheres absolute or to a gas turbine plant used to propel the ship. According to another alternative, the pressure reducing valve 29 is used to reduce the pressure to that in the tanks 10 directly, omitting the separation of volatile gases.

Further, the invention provides an apparatus which is of simple construction and which uses equipment on which no complicated demands need be made.

What is claimed is:

1. A process of treating and utilizing vaporized gas from a liquified gas tank of a ship for transporting liquified combustible gas comprising the steps of drawing off a flow of vaporized gas from at least one gas tank;

compressing said flow of vaporized gas;

dividing the compressed flow of gas into at least two component flows;

feeding one of said gas component flows to a propulsion unit of the ship;

compressing a second of said gas component flows;

passing said compressed second gas component flow into heat exchange relation with a continued flow of said flow of vaporized gas to heat said continued flow of vaporized gas prior to compressing of said continued flow of vaporized gas; and

thereafter reducing the pressure of said second gas component flow and feeding a liquid part of the reduced pressure gas component flow to at least one gas tank.

2. A process as set forth in claim 1 which further comprises the step of cooling said flow of compressed gas prior to dividing into said component flows.

3. A process as set forth in claim 1 wherein the full flow of said vaporized gas from one tank is compressed to a pressure demanded by the propulsion unit.

4. A process as set forth in claim 1 which further comprises the step of separating volatile constituents from said reduced pressure gas component flow.

5. A process as set forth in claim 4 wherein said step of reducing the pressure of said second gas component flow includes expanding said second gas component flow to a pressure corresponding to a delivery pressure of said vaporized gas from the tank and wherein the separated volatile constituents pass in heat exchange relation with said flow of vaporized gas and are added to said one gas component flow.

6. An apparatus for treating and utilizing vaporized gas from a liquified gas tank of a ship for transporting liquified combustible gas comprising at least one gas tank;

means for drawing off a flow of vaporized gas from said tank;

a first compressor connected to said for drawing off means for compressing the flow of vaporized gas;

a first branch line connected to said compressor to deliver one component flow of the compressed gas flow to a propulsion unit of the ship;

a second compressor connected to said first compressor to receive and compress a second component flow'of the compressed gas flow from said first compressor;

a heat exchanger connected with said means and to said second compressor to receive the flow of vaporized gas from said tank and the flow of the compressed second gas component flow from said second compressor in heat exchange relation to heat the flow of vaporized gas and cool the second gas component flow; and

a pressure reducing means connected to said heat exchanger and said tank to deliver the second gas component flow to said tank in at least partly liquified form.

7. An apparatus as set forth in claim 6 which further comprises a second branch line between said first compressor and said second compressor to convey the second gas component therebetween.

8. An apparatus as set forth in claim 6 which further comprises an after-cooler downstream of said first compressor for cooling the compressed flow of vaporized gas.

9. An apparatus as set forth in claim 6 which further comprises a separator connected to said heat exchanger to receive the cooled second gas component flow, a cooling passage in said heat exchanger, a line between said separator and said cooling passage for passing separated volatile gas constituents from the second gas component flow through said cooling passsage, a line between said cooling passage and said first branch line to deliver the volatile gas constituents thereto and a line between said separator and said gas tank to deliver liquified gas thereto.

Patent Citations
Cited PatentFiling datePublication dateApplicantTitle
US2795937 *Mar 31, 1955Jun 18, 1957Phillips Petroleum CoProcess and apparatus for storage or transportation of volatile liquids
US2940268 *May 10, 1954Jun 14, 1960Constock Liquid Methane CorpApparatus for transporting, storing and using natural gas
US3229473 *Dec 7, 1962Jan 18, 1966Exxon Research Engineering CoVessel for transporting low temperature liquids
US3303660 *Sep 27, 1965Feb 14, 1967Berg Clyde H OProcess and apparatus for cryogenic storage
US3383881 *Oct 28, 1966May 21, 1968Phillips Petroleum CoMethod of controlling composition by pressure
US3768271 *Jan 18, 1972Oct 30, 1973L DenisMethod and plant for storing and transporting a liquefied combustible gas
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Citing PatentFiling datePublication dateApplicantTitle
US4294323 *Sep 13, 1979Oct 13, 1981Cryogenics UnlimitedCryogenic powered vehicle
US4479354 *Oct 1, 1981Oct 30, 1984Thomas CosbyLimited expansion vapor cycle
US4505128 *Aug 8, 1983Mar 19, 1985Bio-Care IncorporatedCompressor system for discharging dry air
US4987932 *Oct 2, 1989Jan 29, 1991Pierson Robert MProcess and apparatus for rapidly filling a pressure vessel with gas
US5211021 *Feb 28, 1991May 18, 1993Pierson Robert MApparatus for rapidly filling pressure vessels with gas
US5590535 *Nov 13, 1995Jan 7, 1997Chicago Bridge & Iron Technical Services CompanyProcess and apparatus for conditioning cryogenic fuel to establish a selected equilibrium pressure
US5687776 *Jul 1, 1994Nov 18, 1997Chicago Bridge & Iron Technical Services CompanyMethod and apparatus for fueling vehicles with liquefied cryogenic fuel
US5771946 *Jun 17, 1996Jun 30, 1998Chicago Bridge & Iron Technical Services CompanyMethod and apparatus for fueling vehicles with liquefied cryogenic fuel
US6584781Aug 31, 2001Jul 1, 2003Enersea Transport, LlcMethods and apparatus for compressed gas
US6655155Oct 8, 2002Dec 2, 2003Enersea Transport, LlcMethods and apparatus for loading compressed gas
US6672104Mar 26, 2003Jan 6, 2004Exxonmobil Upstream Research CompanyReliquefaction of boil-off from liquefied natural gas
US6725671Dec 11, 2002Apr 27, 2004Enersea Transport, LlcMethods and apparatus for compressed gas
US6994104Aug 31, 2001Feb 7, 2006Enersea Transport, LlcModular system for storing gas cylinders
US7257952Sep 21, 2005Aug 21, 2007Enersea Transport LlcMethods and apparatus for compressed gas
US8256230Jan 15, 2010Sep 4, 2012Hyung-Su AnOperating system of liquefied natural gas ship for subcooling and liquefying boil-off gas
US8499569Sep 12, 2005Aug 6, 2013Argent Marine Management, Inc.System and process for transporting LNG by non-self-propelled marine LNG carrier
US9168993Apr 21, 2015Oct 27, 2015Daewoo Shipbuilding & Marine Engineering Co., Ltd.Liquefied gas treatment system for vessel
US20020046773 *Aug 31, 2001Apr 25, 2002Bishop William M.Methods and apparatus for compressible gas
US20020172858 *May 15, 2001Nov 21, 2002Daniel AshikianThermo-dynamic battery storage unit
US20050217281 *Feb 2, 2005Oct 6, 2005Linde AktiengesellschaftMethod for the reliquefaction of gas
US20060011235 *Sep 21, 2005Jan 19, 2006Enersea Transport, Llc A Limited Liability Corporation Of TexasMethods and apparatus for compressed gas
US20060053806 *Sep 12, 2005Mar 16, 2006Argent Marine Operations, Inc.System and process for transporting LNG by non-self-propelled marine LNG carrier
US20080120993 *Dec 10, 2007May 29, 2008Hyung-Su AnOperating system of liquefied natural gas ship for sub-cooling and liquefying boil-off gas
US20090100844 *Nov 11, 2004Apr 23, 2009Hamworthy Gas Systems AsApparatus and method for controlling temperature in a boil-off gas
US20090113929 *Apr 2, 2007May 7, 2009Hamworthy Gas Systems AsMethod and apparatus for pre-heating lng boil-off gas to ambient temperature prior to compression in a reliquefaction system
US20090133674 *Dec 11, 2008May 28, 2009Daewoo Shipbuilding & Marine Engineering Co., Ltd.Fuel gas supply system and method of an lng carrier
US20100139316 *Jan 15, 2010Jun 10, 2010Hyung-Su AnOperating System of Liquefied Natural Gas Ship for Subcooling and Liquefying Boil-Off Gas
US20110067440 *May 18, 2009Mar 24, 2011Michiel Gijsbert Van AkenMethod of cooling and liquefying a hydrocarbon stream, an apparatus therefor, and a floating structure, caisson or off-shore platform comprising such an apparatus
US20140352330 *Jan 29, 2014Dec 4, 2014Hyundai Heavy Industries Co., Ltd.Liquefied gas treatment system
US20140352331 *Jan 29, 2014Dec 4, 2014Hyundai Heavy Industries Co., Ltd.Liquefied gas treatment system
US20150007585 *Jul 8, 2013Jan 8, 2015The Boeing CompanySystems and Methods for Maintaining Pressure in Cryogenic Storage Tanks
US20160290258 *Apr 3, 2015Oct 6, 2016Electro-Motive Diesel, Inc.Method and system for reducing engine nox emissions by fuel dilution
CN100529620CJul 25, 2005Aug 19, 2009大宇造船海洋株式会社Operating system of liquefied natural gas ship for sub-cooling and liquefying boil-off gas
CN103717959A *Apr 3, 2012Apr 9, 2014液化气设备有限公司Method of cooling boil off gas and apparatus therefor
CN103717959B *Apr 3, 2012Jul 15, 2015液化气设备有限公司(英国)Method of cooling boil off gas and apparatus therefor
CN104024100A *Oct 24, 2013Sep 3, 2014大宇造船海洋株式会社System for processing liquefied gas in ship
CN104214507A *Feb 25, 2014Dec 17, 2014现代重工业株式会社Liquefied gas treatment system
CN105324302A *Jun 26, 2014Feb 10, 2016大宇造船海洋株式会社System and method for treating boil-off gas in ship
EP1562013A1 *Feb 1, 2005Aug 10, 2005Linde AktiengesellschaftMethod of gas reliquefaction
WO1982000492A1 *Aug 1, 1980Feb 18, 1982Pefley RLiquid fuel system method and apparatus
WO2002095285A1 *May 17, 2001Nov 28, 2002Osaka Gas Co., Ltd.Device and method for pressure control of cargo tank of liquefied natural gas carrier
WO2005040667A1 *Oct 28, 2004May 6, 2005Moss Maritime AsDevice for storage and transport of liquefied natural gas
WO2005047761A1 *Nov 11, 2004May 26, 2005Hamworthy Kse Gas Systems AsApparatus and method for controlling temperature in a boil-off gas
WO2006031634A1 *Sep 12, 2005Mar 23, 2006Argent Marine Operations, IncSystem and process for transporting lng by non-self-propelled marine lng carrier
WO2009141293A3 *May 18, 2009Jun 13, 2013Shell Internationale Research Maatschappij B.V.Method of cooling and liquefying a hydrocarbon stream, an apparatus therefor, and a floating structure, caisson or off-shore platform comprising such an apparatus
WO2014065618A1 *Oct 24, 2013May 1, 2014Daewoo Shipbuilding & Marine Engineering Co., Ltd.System for processing liquefied gas in ship
Classifications
U.S. Classification60/651, 62/50.3, 60/671, 62/47.1, 62/240, 62/7
International ClassificationC10L3/10, B63B25/16, F25J1/00, F17C9/04, F17C13/00, B63H21/00, B63J2/14, F25J1/02, B63J99/00
Cooperative ClassificationF17C2265/03, B63J99/00, F25J1/004, F25J1/0202, F25J2220/62, B63H21/00, F25J1/0025, F17C9/04, F25J1/0277, F25J2230/60, F25J1/023
European ClassificationF25J1/02Z4U4, F25J1/02K2C, F25J1/00A6B, F25J1/00C2F, F25J1/02A2, B63J99/00, F17C9/04, F25J1/00, B63H21/00