EP0681671B1 - Process and system for, respectively, the utilization and provision of fuel gas - Google Patents

Process and system for, respectively, the utilization and provision of fuel gas Download PDF

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Publication number
EP0681671B1
EP0681671B1 EP94906400A EP94906400A EP0681671B1 EP 0681671 B1 EP0681671 B1 EP 0681671B1 EP 94906400 A EP94906400 A EP 94906400A EP 94906400 A EP94906400 A EP 94906400A EP 0681671 B1 EP0681671 B1 EP 0681671B1
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EP
European Patent Office
Prior art keywords
gas
boil
compressor
liquefied
heat exchanger
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EP94906400A
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German (de)
French (fr)
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EP0681671A1 (en
Inventor
Per E. Christiansen
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Kvaerner Moss Technology AS
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Kvaerner Moss Technology AS
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    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F17—STORING OR DISTRIBUTING GASES OR LIQUIDS
    • F17C—VESSELS FOR CONTAINING OR STORING COMPRESSED, LIQUEFIED OR SOLIDIFIED GASES; FIXED-CAPACITY GAS-HOLDERS; FILLING VESSELS WITH, OR DISCHARGING FROM VESSELS, COMPRESSED, LIQUEFIED, OR SOLIDIFIED GASES
    • F17C9/00—Methods or apparatus for discharging liquefied or solidified gases from vessels not under pressure
    • F17C9/02—Methods or apparatus for discharging liquefied or solidified gases from vessels not under pressure with change of state, e.g. vaporisation
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F17—STORING OR DISTRIBUTING GASES OR LIQUIDS
    • F17C—VESSELS FOR CONTAINING OR STORING COMPRESSED, LIQUEFIED OR SOLIDIFIED GASES; FIXED-CAPACITY GAS-HOLDERS; FILLING VESSELS WITH, OR DISCHARGING FROM VESSELS, COMPRESSED, LIQUEFIED, OR SOLIDIFIED GASES
    • F17C2221/00—Handled fluid, in particular type of fluid
    • F17C2221/03—Mixtures
    • F17C2221/032—Hydrocarbons
    • F17C2221/035—Propane butane, e.g. LPG, GPL
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F17—STORING OR DISTRIBUTING GASES OR LIQUIDS
    • F17C—VESSELS FOR CONTAINING OR STORING COMPRESSED, LIQUEFIED OR SOLIDIFIED GASES; FIXED-CAPACITY GAS-HOLDERS; FILLING VESSELS WITH, OR DISCHARGING FROM VESSELS, COMPRESSED, LIQUEFIED, OR SOLIDIFIED GASES
    • F17C2223/00—Handled fluid before transfer, i.e. state of fluid when stored in the vessel or before transfer from the vessel
    • F17C2223/01—Handled fluid before transfer, i.e. state of fluid when stored in the vessel or before transfer from the vessel characterised by the phase
    • F17C2223/0146—Two-phase
    • F17C2223/0153—Liquefied gas, e.g. LPG, GPL
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F17—STORING OR DISTRIBUTING GASES OR LIQUIDS
    • F17C—VESSELS FOR CONTAINING OR STORING COMPRESSED, LIQUEFIED OR SOLIDIFIED GASES; FIXED-CAPACITY GAS-HOLDERS; FILLING VESSELS WITH, OR DISCHARGING FROM VESSELS, COMPRESSED, LIQUEFIED, OR SOLIDIFIED GASES
    • F17C2223/00—Handled fluid before transfer, i.e. state of fluid when stored in the vessel or before transfer from the vessel
    • F17C2223/03—Handled fluid before transfer, i.e. state of fluid when stored in the vessel or before transfer from the vessel characterised by the pressure level
    • F17C2223/033—Small pressure, e.g. for liquefied gas
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F17—STORING OR DISTRIBUTING GASES OR LIQUIDS
    • F17C—VESSELS FOR CONTAINING OR STORING COMPRESSED, LIQUEFIED OR SOLIDIFIED GASES; FIXED-CAPACITY GAS-HOLDERS; FILLING VESSELS WITH, OR DISCHARGING FROM VESSELS, COMPRESSED, LIQUEFIED, OR SOLIDIFIED GASES
    • F17C2227/00—Transfer of fluids, i.e. method or means for transferring the fluid; Heat exchange with the fluid
    • F17C2227/01—Propulsion of the fluid
    • F17C2227/0128—Propulsion of the fluid with pumps or compressors
    • F17C2227/0135—Pumps
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F17—STORING OR DISTRIBUTING GASES OR LIQUIDS
    • F17C—VESSELS FOR CONTAINING OR STORING COMPRESSED, LIQUEFIED OR SOLIDIFIED GASES; FIXED-CAPACITY GAS-HOLDERS; FILLING VESSELS WITH, OR DISCHARGING FROM VESSELS, COMPRESSED, LIQUEFIED, OR SOLIDIFIED GASES
    • F17C2227/00—Transfer of fluids, i.e. method or means for transferring the fluid; Heat exchange with the fluid
    • F17C2227/01—Propulsion of the fluid
    • F17C2227/0128—Propulsion of the fluid with pumps or compressors
    • F17C2227/0157—Compressors
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F17—STORING OR DISTRIBUTING GASES OR LIQUIDS
    • F17C—VESSELS FOR CONTAINING OR STORING COMPRESSED, LIQUEFIED OR SOLIDIFIED GASES; FIXED-CAPACITY GAS-HOLDERS; FILLING VESSELS WITH, OR DISCHARGING FROM VESSELS, COMPRESSED, LIQUEFIED, OR SOLIDIFIED GASES
    • F17C2227/00—Transfer of fluids, i.e. method or means for transferring the fluid; Heat exchange with the fluid
    • F17C2227/01—Propulsion of the fluid
    • F17C2227/0128—Propulsion of the fluid with pumps or compressors
    • F17C2227/0171—Arrangement
    • F17C2227/0178—Arrangement in the vessel
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F17—STORING OR DISTRIBUTING GASES OR LIQUIDS
    • F17C—VESSELS FOR CONTAINING OR STORING COMPRESSED, LIQUEFIED OR SOLIDIFIED GASES; FIXED-CAPACITY GAS-HOLDERS; FILLING VESSELS WITH, OR DISCHARGING FROM VESSELS, COMPRESSED, LIQUEFIED, OR SOLIDIFIED GASES
    • F17C2227/00—Transfer of fluids, i.e. method or means for transferring the fluid; Heat exchange with the fluid
    • F17C2227/03—Heat exchange with the fluid
    • F17C2227/0367—Localisation of heat exchange
    • F17C2227/0388—Localisation of heat exchange separate
    • F17C2227/0393—Localisation of heat exchange separate using a vaporiser
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F17—STORING OR DISTRIBUTING GASES OR LIQUIDS
    • F17C—VESSELS FOR CONTAINING OR STORING COMPRESSED, LIQUEFIED OR SOLIDIFIED GASES; FIXED-CAPACITY GAS-HOLDERS; FILLING VESSELS WITH, OR DISCHARGING FROM VESSELS, COMPRESSED, LIQUEFIED, OR SOLIDIFIED GASES
    • F17C2250/00—Accessories; Control means; Indicating, measuring or monitoring of parameters
    • F17C2250/06—Controlling or regulating of parameters as output values
    • F17C2250/0605—Parameters
    • F17C2250/0621—Volume
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F17—STORING OR DISTRIBUTING GASES OR LIQUIDS
    • F17C—VESSELS FOR CONTAINING OR STORING COMPRESSED, LIQUEFIED OR SOLIDIFIED GASES; FIXED-CAPACITY GAS-HOLDERS; FILLING VESSELS WITH, OR DISCHARGING FROM VESSELS, COMPRESSED, LIQUEFIED, OR SOLIDIFIED GASES
    • F17C2250/00—Accessories; Control means; Indicating, measuring or monitoring of parameters
    • F17C2250/06—Controlling or regulating of parameters as output values
    • F17C2250/0605—Parameters
    • F17C2250/0631—Temperature
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F17—STORING OR DISTRIBUTING GASES OR LIQUIDS
    • F17C—VESSELS FOR CONTAINING OR STORING COMPRESSED, LIQUEFIED OR SOLIDIFIED GASES; FIXED-CAPACITY GAS-HOLDERS; FILLING VESSELS WITH, OR DISCHARGING FROM VESSELS, COMPRESSED, LIQUEFIED, OR SOLIDIFIED GASES
    • F17C2265/00—Effects achieved by gas storage or gas handling
    • F17C2265/02—Mixing fluids
    • F17C2265/022—Mixing fluids identical fluid
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F17—STORING OR DISTRIBUTING GASES OR LIQUIDS
    • F17C—VESSELS FOR CONTAINING OR STORING COMPRESSED, LIQUEFIED OR SOLIDIFIED GASES; FIXED-CAPACITY GAS-HOLDERS; FILLING VESSELS WITH, OR DISCHARGING FROM VESSELS, COMPRESSED, LIQUEFIED, OR SOLIDIFIED GASES
    • F17C2265/00—Effects achieved by gas storage or gas handling
    • F17C2265/03—Treating the boil-off
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F17—STORING OR DISTRIBUTING GASES OR LIQUIDS
    • F17C—VESSELS FOR CONTAINING OR STORING COMPRESSED, LIQUEFIED OR SOLIDIFIED GASES; FIXED-CAPACITY GAS-HOLDERS; FILLING VESSELS WITH, OR DISCHARGING FROM VESSELS, COMPRESSED, LIQUEFIED, OR SOLIDIFIED GASES
    • F17C2265/00—Effects achieved by gas storage or gas handling
    • F17C2265/03—Treating the boil-off
    • F17C2265/032—Treating the boil-off by recovery
    • F17C2265/036—Treating the boil-off by recovery with heating
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F17—STORING OR DISTRIBUTING GASES OR LIQUIDS
    • F17C—VESSELS FOR CONTAINING OR STORING COMPRESSED, LIQUEFIED OR SOLIDIFIED GASES; FIXED-CAPACITY GAS-HOLDERS; FILLING VESSELS WITH, OR DISCHARGING FROM VESSELS, COMPRESSED, LIQUEFIED, OR SOLIDIFIED GASES
    • F17C2265/00—Effects achieved by gas storage or gas handling
    • F17C2265/03—Treating the boil-off
    • F17C2265/032—Treating the boil-off by recovery
    • F17C2265/037—Treating the boil-off by recovery with pressurising

Definitions

  • the invention relates to a process for the utilization of boil-off (decoction) from liquefied petroleum gas as fuel gas in combination with gas produced by evaporation of the liquefied petroleum gas, where the boil-off and evaporated gas are brought together and compressed.
  • the invention also relates to a system for carrying out the method, wherein boil-off and evaporated gas are brought together and compressed, comprising a storage tank for liquefied petroleum gas, an outlet line for decoction from the storage tank, an outlet line for liquefied gas from the storage tank, an evaporator in the outlet line for liquefied gas, a flowline (header) connected to the two outlet lines, a compressor connected to the flowline, and a pressure pipe from the compressor.
  • a storage tank for liquefied petroleum gas comprising a storage tank for liquefied petroleum gas, an outlet line for decoction from the storage tank, an outlet line for liquefied gas from the storage tank, an evaporator in the outlet line for liquefied gas, a flowline (header) connected to the two outlet lines, a compressor connected to the flowline, and a pressure pipe from the compressor.
  • the point of departure is the situation currently found aboard LNG ships, i.e., ships designed to carry liquefied natural gas.
  • Ships carrying liquefied natural gas (LNG ships) at atmospheric pressure normally are not equipped with recondensation systems. Therefore, the gas which boils off as a result of leakage of heat into the tanks, here defined as decoction (boil-off), is used as fuel gas in the ship's steam boiler.
  • the temperature of the cargo at atmospheric pressure will be about minus 160°C for most LNG mixtures, while the gas temperature and pressure requirements at the inlet to the boiler burners are, respectively, plus 30°C and minimum 0.5 bar g.
  • the boil-off is not sufficient to meet the total requirement for the boiler, the gas amount may be increased by evaporating LNG, here defined as gas produced by the evaporation of the liquefied gas, which is taken directly from the tanks.
  • a compressor maintains the desired tank pressure by evacuating boil-off.
  • the boil-off will receive some heat in the tank dome and the pipe system, causing the temperature at the inlet to a separator placed in front of the compressor to be increased from minus 160°C to about minus 120°C.
  • the pressure increase in the compressor causes a temperature rise of about 30°C.
  • a heat exchanger (heater) is installed after the compressor for further heating of the gas.
  • a pump suitable for this purpose is started in one of the tanks, and LNG at minus 160°C is sent on to an evaporator.
  • the gas is evaporated and overheated to about minus 60°C, prior to entering said separator and mixing with the boil-off.
  • the separator is considered necessary because LNG taken from the bottom of the tanks contains small amounts of heavier hydrocarbons which have a droplet form after the evaporation, or conceivably can condense in the inlet to the compressor and damage it.
  • boil-off is used alone, the separator per se is not necessary, nor is it necessary if the temperature is sufficiently high in front of the compressor, eliminating the danger of precipitation of liquid drops.
  • the system should be run either with boil-off alone or with evaporation of LNG.
  • the amounts will vary from 0 to 100% for both sources. If, for example, maximum gas consumption for the boilers is 5000 kg/hour and the boil-off amount is 4000 kg/hour, then 1000 kg/hour must be supplied via the evaporator. If the boil-off amount is 2000 kg/hour, then 3000 kg/hour must be supplied via the evaporator, etc.
  • the suction temperature for the compressor could vary between the extremes of minus 60°C and minus 120°C.
  • An existing system of this type involves an arrangement requiring four main components, namely: an evaporator, separator, compressor and heater.
  • the operating temperatures are such that these components must be classified as cryogenic equipment, with special requirements with regard to materials and construction. This also applies to the pipework and instrumentation.
  • the purpose of the present invention is to simplify the process and the system.
  • the aforementioned system be designed such that the evaporator is constructed as a combined heat exchanger having two separate throughflow tube bundles disposed in a common surrounding shell, one said bundle being connected to the outlet line for liquefied gas for the evaporation thereof, and the other tube bundle being connected to the outlet line for boil-off for the overheating thereof, which tubes flow into a common mixing chamber which is connected to the flowline.
  • the process and the system are radically simplified. Because the suction temperature of the compressor is raised substantially, the separator may be omitted, and the compressor need not be cryogenic, with the special requirements for materials, construction and design associated therewith. Insulation of the pipelines may be omitted, and ice formation on the valves and expansion members is avoided. This simplification results in reduction of the amount of required space and a less complicated pipework system.
  • the combined heat exchanger can be supplied at a price which is not substantially higher than that of each of the heat exchangers (evaporator and heater ) in use today. The overall capital costs and operating expenses (including maintenance) over the lifetime of the ship will be reduced substantially.
  • Thermal engineering calculations indicate that it is possible to construct the combined heat exchanger with dimensions covering all conditions from 0-100% boil-off and from 0-100% evaporation. Furthermore, the apparatus may be regulated such that the gas exiting the heat exchanger maintains a temperature of plus 10°C, so that further heating of 20-30°C in the compressor will ensure that the gas supplied to the boilers has the correct temperature (and pressure).
  • numeral 1 designates a storage tank for liquefied petroleum gas, for example a tank for LNG aboard an LNG ship.
  • boil-off decoction
  • This boil-off collects in the dome 2 of the storage tank and may be removed through an outlet line 3.
  • This outlet line 3 runs to a separator 4, from which runs a line 5 to a compressor 6.
  • compressor 6 In compressor 6 the boil-off is compressed, with an attendant increasing of the temperature. Further temperature increases take place in a heater 7, from which runs a line 8 carrying fuel gas.
  • Tank 1 contains liquefied natural gas having a temperature of around minus 160°.
  • the boil-off, which is removed through line 3, will as a result of the supply of heat in dome 2 and in line 3 have a temperature of around minus 120°C at separator 4.
  • compressor 6 the temperature increases to about minus 90°C, and in heater 7 the temperature is increased to plus 40°C.
  • the system is designed in such a way that if the decoction is insufficient, i.e., if greater amounts of fuel gas are needed than the boil-off can supply, then liquefied natural gas is extracted by means of a pump 9. From this submerged pump runs outlet line 10 for liquefied gas, on to an evaporator 11. From evaporator 11 runs a line 12 to separator 4. When the evaporated gas arrives at the separator it will have a temperature of about minus 60°C.
  • the separator is considered necessary because the liquefied gas removed from the bottom of tank 1 after the evaporation contains small amounts of liquid drops. These can conceivably condense in the inlet of compressor 6 and damage it. For boil-off alone the separator is not necessary, nor is it necessary if the temperature is sufficiently high prior to the compressor to ensure that there is no danger of precipitation of liquid drops.
  • FIG. 2 A schematic view of the system according to the invention is shown in Figure 2.
  • the system is intended to be connected to a storage tank 1 with a dome 2 and submerged pump 9 and an outlet line 3 for boil-off, as well as an outlet line 10 for liquefied petroleum gas, as in the system in Figure 1.
  • the two outlet lines 3 and 10 are led to a combined heat exchanger 13.
  • This has two separate tube bundles 14 and 15 in the same shell, namely a bundle 15 for the evaporation of the liquefied gas and a bundle 14 for the overheating of boil-off. Both tube bundles flow into a common mixing chamber 16. From there runs a line 17 to a compressor 18. From compressor 18 runs a fuel gas line 19.
  • the combined heat exchanger may be regulated such that the mixed gas in line 17 will have a temperature of plus 10°C.
  • the fuel gas supplied by compressor 18 will have a temperature of around 30°C.
  • the compressor in Figure 2 may be of a normal type since the suction temperature, as mentioned above, will be high (plus 10°C instead of minus 120°C as in Figure 1).
  • Volume control is effected in the system in Figure 1 by means of a control valve at the inlet of evaporator 11 and by regulation of the suction volume of compressor 6.
  • a line 20 branches off from line 10 to the mixing chamber 16 of the combined heat exchanger.
  • Quadrangle 21 represents a temperature control.
  • Quadrangle 22 represents a flow control.
  • the flow control directs a control valve 23 in the boil-off line 3 as well as a control valve 24 in line 10. Both of these control loops will in practice be integrated in a common data processor which also handles the other control functions in the system.
  • Temperature control out from the combined heat exchanger is carried out here by means of injection of liquefied petroleum gas through line 20 in mixing chamber 16 when the heat exchanger is working with both overheating of boil-off and the evaporation of liquefied gas.
  • the temperature is controlled by means of pressure adjustment of the supply of vapour through line 25. Condensate is eliminated through line 26.
  • the invention is not limited to LNG as gas.

Abstract

In a system for the provision of fuel gas from decoction (boil-off) from liquefied petroleum gas and optionally gas produced by the evaporation of the liquefied gas, there is used a combined heat exchanger (13), wherein boil-off and liquefied petroleum gas are heated. Via a common mixing chamber (16) in the combined heat exchanger a combined stream of overheated gas may be supplied to a compressor (18). The compressor (18) may advantageously be of a normal type since its suction temperature will be sufficiently high to allow this, precisely as a result of the heating and evaporation, respectively, in the combined heat exchanger.

Description

The invention relates to a process for the utilization of boil-off (decoction) from liquefied petroleum gas as fuel gas in combination with gas produced by evaporation of the liquefied petroleum gas, where the boil-off and evaporated gas are brought together and compressed.
The invention also relates to a system for carrying out the method, wherein boil-off and evaporated gas are brought together and compressed, comprising a storage tank for liquefied petroleum gas, an outlet line for decoction from the storage tank, an outlet line for liquefied gas from the storage tank, an evaporator in the outlet line for liquefied gas, a flowline (header) connected to the two outlet lines, a compressor connected to the flowline, and a pressure pipe from the compressor.
As the technical background for the invention, the point of departure is the situation currently found aboard LNG ships, i.e., ships designed to carry liquefied natural gas. Ships carrying liquefied natural gas (LNG ships) at atmospheric pressure normally are not equipped with recondensation systems. Therefore, the gas which boils off as a result of leakage of heat into the tanks, here defined as decoction (boil-off), is used as fuel gas in the ship's steam boiler. The temperature of the cargo at atmospheric pressure will be about minus 160°C for most LNG mixtures, while the gas temperature and pressure requirements at the inlet to the boiler burners are, respectively, plus 30°C and minimum 0.5 bar g. When under certain operating conditions the boil-off is not sufficient to meet the total requirement for the boiler, the gas amount may be increased by evaporating LNG, here defined as gas produced by the evaporation of the liquefied gas, which is taken directly from the tanks.
In a common arrangement today for the utilization of boil-off and gas produced by evaporation of the liquefied petroleum gas, a compressor maintains the desired tank pressure by evacuating boil-off. The boil-off will receive some heat in the tank dome and the pipe system, causing the temperature at the inlet to a separator placed in front of the compressor to be increased from minus 160°C to about minus 120°C.
The pressure increase in the compressor causes a temperature rise of about 30°C. To enable the supplying of the gas to the machine room with a temperature of about plus 30°C, a heat exchanger (heater) is installed after the compressor for further heating of the gas.
If it is necessary to increase the amount of gas supplied to the boilers, a pump suitable for this purpose is started in one of the tanks, and LNG at minus 160°C is sent on to an evaporator. Here the gas is evaporated and overheated to about minus 60°C, prior to entering said separator and mixing with the boil-off. The separator is considered necessary because LNG taken from the bottom of the tanks contains small amounts of heavier hydrocarbons which have a droplet form after the evaporation, or conceivably can condense in the inlet to the compressor and damage it. When boil-off is used alone, the separator per se is not necessary, nor is it necessary if the temperature is sufficiently high in front of the compressor, eliminating the danger of precipitation of liquid drops.
It should be possible for the system to be run either with boil-off alone or with evaporation of LNG. The amounts will vary from 0 to 100% for both sources. If, for example, maximum gas consumption for the boilers is 5000 kg/hour and the boil-off amount is 4000 kg/hour, then 1000 kg/hour must be supplied via the evaporator. If the boil-off amount is 2000 kg/hour, then 3000 kg/hour must be supplied via the evaporator, etc. Thus, the suction temperature for the compressor could vary between the extremes of minus 60°C and minus 120°C.
An existing system of this type involves an arrangement requiring four main components, namely: an evaporator, separator, compressor and heater. The operating temperatures are such that these components must be classified as cryogenic equipment, with special requirements with regard to materials and construction. This also applies to the pipework and instrumentation.
The purpose of the present invention is to simplify the process and the system.
According to the invention, therefore, we propose a process as described in the introduction above, characterized in that the boil-off and liquefied gas prior to the compression are overheated and evaporated, respectively, in their separate sections in a combined heat exchanger and are brought together in a common mixing chamber.
With regard to the new system, it is proposed according to the invention that the aforementioned system be designed such that the evaporator is constructed as a combined heat exchanger having two separate throughflow tube bundles disposed in a common surrounding shell, one said bundle being connected to the outlet line for liquefied gas for the evaporation thereof, and the other tube bundle being connected to the outlet line for boil-off for the overheating thereof, which tubes flow into a common mixing chamber which is connected to the flowline.
By means of the invention, the process and the system are radically simplified. Because the suction temperature of the compressor is raised substantially, the separator may be omitted, and the compressor need not be cryogenic, with the special requirements for materials, construction and design associated therewith. Insulation of the pipelines may be omitted, and ice formation on the valves and expansion members is avoided. This simplification results in reduction of the amount of required space and a less complicated pipework system. The combined heat exchanger can be supplied at a price which is not substantially higher than that of each of the heat exchangers (evaporator and heater ) in use today. The overall capital costs and operating expenses (including maintenance) over the lifetime of the ship will be reduced substantially.
Thermal engineering calculations indicate that it is possible to construct the combined heat exchanger with dimensions covering all conditions from 0-100% boil-off and from 0-100% evaporation. Furthermore, the apparatus may be regulated such that the gas exiting the heat exchanger maintains a temperature of plus 10°C, so that further heating of 20-30°C in the compressor will ensure that the gas supplied to the boilers has the correct temperature (and pressure).
The invention will now be explained in more detail, with reference to the drawings, where:
  • Fig. 1 is a purely schematic view of a known system,
  • Fig. 2 shows a system according to the invention, and
  • Fig. 3 shows the new combined heat exchanger with associated control system.
    • In Figure 1, numeral 1 designates a storage tank for liquefied petroleum gas, for example a tank for LNG aboard an LNG ship. As a result of heat penetration from the surroundings, so-called boil-off (decoction) will occur. This boil-off collects in the dome 2 of the storage tank and may be removed through an outlet line 3. This outlet line 3 runs to a separator 4, from which runs a line 5 to a compressor 6. In compressor 6 the boil-off is compressed, with an attendant increasing of the temperature. Further temperature increases take place in a heater 7, from which runs a line 8 carrying fuel gas.
    Tank 1 contains liquefied natural gas having a temperature of around minus 160°. The boil-off, which is removed through line 3, will as a result of the supply of heat in dome 2 and in line 3 have a temperature of around minus 120°C at separator 4. In compressor 6 the temperature increases to about minus 90°C, and in heater 7 the temperature is increased to plus 40°C.
    The system is designed in such a way that if the decoction is insufficient, i.e., if greater amounts of fuel gas are needed than the boil-off can supply, then liquefied natural gas is extracted by means of a pump 9. From this submerged pump runs outlet line 10 for liquefied gas, on to an evaporator 11. From evaporator 11 runs a line 12 to separator 4. When the evaporated gas arrives at the separator it will have a temperature of about minus 60°C.
    The separator is considered necessary because the liquefied gas removed from the bottom of tank 1 after the evaporation contains small amounts of liquid drops. These can conceivably condense in the inlet of compressor 6 and damage it. For boil-off alone the separator is not necessary, nor is it necessary if the temperature is sufficiently high prior to the compressor to ensure that there is no danger of precipitation of liquid drops.
    It is apparent from Figure 1 and the typical temperatures indicated therein that the operating conditions are such as to require that the components -- primarily the evaporator 11, separator 4, compressor 6 and heater 7 -- must be classified as cryogenic equipment, with special requirements as regards materials and construction. This applies also to the pipework and instrumentation.
    A schematic view of the system according to the invention is shown in Figure 2. The system is intended to be connected to a storage tank 1 with a dome 2 and submerged pump 9 and an outlet line 3 for boil-off, as well as an outlet line 10 for liquefied petroleum gas, as in the system in Figure 1.
    The two outlet lines 3 and 10 are led to a combined heat exchanger 13. This has two separate tube bundles 14 and 15 in the same shell, namely a bundle 15 for the evaporation of the liquefied gas and a bundle 14 for the overheating of boil-off. Both tube bundles flow into a common mixing chamber 16. From there runs a line 17 to a compressor 18. From compressor 18 runs a fuel gas line 19.
    The combined heat exchanger may be regulated such that the mixed gas in line 17 will have a temperature of plus 10°C. As a consequence hereof, the fuel gas supplied by compressor 18 will have a temperature of around 30°C. The compressor in Figure 2 may be of a normal type since the suction temperature, as mentioned above, will be high (plus 10°C instead of minus 120°C as in Figure 1).
    Volume control is effected in the system in Figure 1 by means of a control valve at the inlet of evaporator 11 and by regulation of the suction volume of compressor 6.
    In Figure 2 one can employ a volume control of the compressor as in Figure 1. Regulation of the combined heat exchanger 13 in Figure 2 can be carried out as exemplified in Figure 3.
    In Figure 3 we again see the combined heat exchanger 13 with the two separate tube bundles 14 and 15, and the two outlet lines 3 and 10. In addition, we find flowline 17, which runs to the compressor, not shown in Figure 3.
    A line 20 branches off from line 10 to the mixing chamber 16 of the combined heat exchanger.
    Quadrangle 21 represents a temperature control. Quadrangle 22 represents a flow control. The flow control directs a control valve 23 in the boil-off line 3 as well as a control valve 24 in line 10. Both of these control loops will in practice be integrated in a common data processor which also handles the other control functions in the system.
    Temperature control out from the combined heat exchanger is carried out here by means of injection of liquefied petroleum gas through line 20 in mixing chamber 16 when the heat exchanger is working with both overheating of boil-off and the evaporation of liquefied gas. In heating of boil-off only, the temperature is controlled by means of pressure adjustment of the supply of vapour through line 25. Condensate is eliminated through line 26.
    The invention is not limited to LNG as gas. Other liquefied gases, the boil-off of which is suitable for fuel/power fuel gas, could of course derive benefit from the invention.

    Claims (3)

    1. A process for the utilization of decoction (boil-off) from liquefied petroleum gas as fuel gas in combination with gas produced by evaporation of the liquefied gas, where boil-off and evaporated gas are brought together and compressed,
      characterized in that the boil-off and the liquefied gas prior to the compression are overheated and evaporated, respectively, in their separate sections of a combined heat exchanger and are brought together in a common mixing chamber.
    2. A system for carrying out the process according to claim 1, where boil-off and evaporated gas are brought together and compressed, comprising
      a storage tank (1) for liquefied petroleum gas,
      an outlet line (3) for boil-off from the storage tank,
      an outlet line (10) for liquefied petroleum gas from the storage tank (1),
      an evaporator (13) in the outlet line (10) for liquefied gas,
      a flowline (17) connected to the two outlet lines (3, 10),
      a compressor (18) connected to the flowline, and
      a pressure line (19) from the compressor,
      characterized in that the evaporator (13) is designed as a combined heat exchanger (13) having two separate throughflow tube bundles (14,15) in a common surrounding shell, one said bundle (15) being connected to the outlet line (10) for liquefied petroleum gas for the evaporation thereof, and the other bundle (14) being connected to the outlet line (3) for boil-off for the overheating thereof, which tube bundles (14, 15) flow into a common mixing chamber (16) connected to the flowline (17).
    3. A system according to claim 2, characterized in that from the outlet line (10) for liquefied petroleum gas from the storage tank (1) there is provided a valve regulated line (20) to the common mixing chamber (16).
    EP94906400A 1993-01-29 1994-01-25 Process and system for, respectively, the utilization and provision of fuel gas Expired - Lifetime EP0681671B1 (en)

    Applications Claiming Priority (3)

    Application Number Priority Date Filing Date Title
    NO930317 1993-01-29
    NO930317A NO176454C (en) 1993-01-29 1993-01-29 Methods and plants for utilizing and providing fuel gas, respectively
    PCT/NO1994/000020 WO1994017325A1 (en) 1993-01-29 1994-01-25 Process and system for, respectively, the utilization and provision of fuel gas

    Publications (2)

    Publication Number Publication Date
    EP0681671A1 EP0681671A1 (en) 1995-11-15
    EP0681671B1 true EP0681671B1 (en) 1998-04-08

    Family

    ID=19895791

    Family Applications (1)

    Application Number Title Priority Date Filing Date
    EP94906400A Expired - Lifetime EP0681671B1 (en) 1993-01-29 1994-01-25 Process and system for, respectively, the utilization and provision of fuel gas

    Country Status (8)

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    EP (1) EP0681671B1 (en)
    JP (1) JPH08505926A (en)
    AU (1) AU6011794A (en)
    DE (1) DE69409504T2 (en)
    ES (1) ES2115935T3 (en)
    FI (1) FI953612A (en)
    NO (1) NO176454C (en)
    WO (1) WO1994017325A1 (en)

    Families Citing this family (19)

    * Cited by examiner, † Cited by third party
    Publication number Priority date Publication date Assignee Title
    NO180426C (en) * 1995-03-16 1997-04-16 Kvaerner Moss Tech As Device for heat exchangers
    NO300288B1 (en) * 1996-02-29 1997-05-05 Kvaerner Maritime As Process for utilizing decoction from liquid gas and plant for carrying out the process
    FR2765238B1 (en) * 1997-06-26 1999-09-03 Renault NEW FUELS CONSISTING OF LIQUEFIED GAS FOR INTERNAL COMBUSTION ENGINES
    GB0001801D0 (en) 2000-01-26 2000-03-22 Cryostar France Sa Apparatus for reliquiefying compressed vapour
    GB0005709D0 (en) 2000-03-09 2000-05-03 Cryostar France Sa Reliquefaction of compressed vapour
    NO314423B1 (en) * 2001-07-31 2003-03-17 Hamworthy Kse As Process of recycling of VOC gas and plant for recycling of VOC gas
    GB0120661D0 (en) * 2001-08-24 2001-10-17 Cryostar France Sa Natural gas supply apparatus
    FI118680B (en) 2003-12-18 2008-02-15 Waertsilae Finland Oy A gas supply arrangement in a craft and a method for controlling gas pressure in a craft gas supply arrangement
    NL1025708C2 (en) * 2004-03-12 2005-09-13 Marine Structure Consul Device for connecting two offshore units.
    GB0501335D0 (en) * 2005-01-21 2005-03-02 Cryostar France Sa Natural gas supply method and apparatus
    DE102006061251B4 (en) * 2006-12-22 2010-11-11 Man Diesel & Turbo Se Gas supply system for a drive
    KR100807963B1 (en) * 2007-01-23 2008-02-28 현대중공업 주식회사 Fuel gas supply system of liquefied natural gas operated in ambient temperature
    KR100805022B1 (en) * 2007-02-12 2008-02-20 대우조선해양 주식회사 Lng cargo tank of lng carrier and method for treating boil-off gas using the same
    DE102007042158A1 (en) * 2007-09-05 2009-03-12 Man Diesel Se Gas supply system for a gas-fueled internal combustion engine
    NO330187B1 (en) * 2008-05-08 2011-03-07 Hamworthy Gas Systems As Gas supply system for gas engines
    RU2696145C1 (en) * 2015-10-16 2019-07-31 Криостар Сас Method and device for treating evaporated gas for feeding at least to an engine
    FR3071276B1 (en) * 2017-09-20 2021-01-01 Gaztransport Et Technigaz DEVICE AND PROCESS FOR SUPPLYING GAS WITH A METHANE RATING OPTIMIZED AT LEAST ONE THERMAL ENGINE, IN PARTICULAR OF A LIQUEFIED GAS TRANSPORT VESSEL
    CN113970065B (en) * 2021-11-09 2022-11-29 新地能源工程技术有限公司 LNG emergency gasification device and method with adjustable heat value
    WO2023156934A1 (en) * 2022-02-17 2023-08-24 Bennamann Services Ltd Systems and methods for vaporization of a liquid

    Family Cites Families (3)

    * Cited by examiner, † Cited by third party
    Publication number Priority date Publication date Assignee Title
    US2456890A (en) * 1945-06-09 1948-12-21 Phillips Petroleum Co Vaporizer
    US2747374A (en) * 1951-08-30 1956-05-29 William O Thompson Liquefied gas system
    NO812328L (en) * 1981-07-08 1983-01-10 Moss Rosenberg Verft As PROCEDURE FOR THE EXPLOITATION OF DECYCLES FROM THE CRYOGENIC LIQUIDS LIKE FUEL IN A TWO-FUEL DIESEL ENGINE, AND SYSTEM FOR USING THE PROCEDURE

    Also Published As

    Publication number Publication date
    ES2115935T3 (en) 1998-07-01
    NO176454C (en) 1995-04-05
    NO930317D0 (en) 1993-01-29
    FI953612A0 (en) 1995-07-28
    JPH08505926A (en) 1996-06-25
    DE69409504D1 (en) 1998-05-14
    FI953612A (en) 1995-07-28
    AU6011794A (en) 1994-08-15
    NO176454B (en) 1994-12-27
    EP0681671A1 (en) 1995-11-15
    DE69409504T2 (en) 1998-09-10
    NO930317L (en) 1994-08-01
    WO1994017325A1 (en) 1994-08-04

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