Fuel treatment system and ship including the same

Abstract

A fuel processing system according to one embodiment of the present invention comprises: a fuel supply unit that supplies liquefied gas from a storage tank to a demand location; a reliquefaction unit that reliquefies the evaporated gas from the storage tank; a depressurization unit that depressurizes the evaporated gas reliquefied in the reliquefaction unit; and a separation unit that separates the evaporated gas depressurized in the depressurization unit into a gaseous substance and a liquid substance. The depressurization unit lowers the pressure of the reliquefied evaporated gas to control the ratio of methane contained in the liquid substance in a saturated state to a value or less, and the separation unit separates the gaseous substance containing methane from the depressurized evaporated gas and then delivers it to the demand location.

Description

Technology Field

[0001] The present invention relates to a fuel processing system and a ship including the same. Background Technology

[0002] Among ships sailing the seas loaded with various types of cargo, liquefied gas carriers that transport liquefied gases such as liquefied natural gas or liquefied petroleum gas are equipped with storage tanks that store gases in a liquid state by forcibly liquefying gases with a boiling point lower than room temperature.

[0003] Liquefied natural gas (LNG) is produced by cooling and liquefying methane (CH4) and ethane (C2H4), which are obtained by refining natural gas extracted from gas fields. It is a colorless, transparent liquid with almost no pollutants and a high calorific value, making it an excellent fuel. On the other hand, liquefied petroleum gas (LPG) consists of propane (C3H8) and butane (C4H8) that are produced along with petroleum from oil fields. 10 It is a gas made by converting a gas with ) as its main component into a liquid, and is widely used as fuel for household, commercial, industrial, and automotive use. Liquefied natural gas has the advantage of high storage efficiency, as it is reduced to 1 / 600 of its volume upon liquefaction, and liquefied petroleum gas is reduced to 1 / 260 of the volume for propane and 1 / 230 of the volume for butane upon liquefaction.

[0004] However, although storage tanks for storing such liquefied gas are equipped with insulation, they cannot completely prevent the vaporization of the liquefied gas. Consequently, evaporated gas in a gaseous state is generated within the storage tank as the liquefied gas evaporates, and since this evaporated gas increases the internal pressure of the storage tank, it must be discharged from the storage tank for safety.

[0005] To reduce the internal pressure of the storage tank, the evaporated gas discharged from the tank is combusted and discarded through a gas combustion unit. However, since evaporated gas also constitutes part of the cargo carried by the ship, its discharge poses a problem as it undermines the reliability of cargo transport. Considering this, the evaporated gas from the storage tank can be re-liquefied and recovered back into the storage tank to lower the internal pressure.

[0006] Meanwhile, the reliquefied evaporated gas can be supplied directly to the engine, etc. Since engine efficiency may decrease depending on the substances contained in the reliquefied evaporated gas or their content, it is necessary to control the substances contained in the reliquefied evaporated gas or their content before supplying it to the engine. The problem to be solved

[0007] The present invention was created to solve the problems of the prior art described above, and aims to provide a fuel processing system capable of processing re-liquefied boil-off gas according to the requirements of a user and supplying it to the user, and a vessel including the same.

[0008] The problems of the present invention are not limited to those mentioned above, and other problems not mentioned will be clearly understood by those skilled in the art from the description below. means of solving the problem

[0009] A fuel processing system according to one aspect of the present invention comprises: a fuel supply unit that supplies liquefied gas from a storage tank to a demand location; a reliquefaction unit that reliquefies the evaporated gas from the storage tank; a depressurization unit that depressurizes the evaporated gas reliquefied in the reliquefaction unit; and a separation unit that separates the evaporated gas depressurized in the depressurization unit into a gaseous substance and a liquid substance. The depressurization unit lowers the pressure of the reliquefied evaporated gas to control the ratio of methane contained in the liquid substance in a saturated state to a value or less, and the separation unit separates the gaseous substance containing methane from the depressurized evaporated gas and then delivers it to the demand location.

[0010] Specifically, the fuel supply unit includes a pressure pump that pressurizes liquefied gas to the required pressure of the demand location; and the liquid material separated in the separation unit can be delivered upstream of the pressure pump.

[0011] Specifically, the fuel supply unit can mix the liquefied gas of the storage tank with the evaporated gas depressurized in the depressurization unit and supply it to the demand location.

[0012] Specifically, the liquefied gas supplied to the above-mentioned demand source may contain methane at a certain percentage or less.

[0013] Specifically, the above-mentioned pressure reduction unit can adjust the ratio of methane contained in the liquid material to a level lower than the ratio of methane required by the above-mentioned demand source.

[0014] Specifically, the above-mentioned pressure reduction unit can control the proportion of methane contained in the liquid material to 15 mol% or less.

[0015] In addition, a vessel according to one embodiment of the present invention may include the fuel processing system.

[0016] Specifically, the vessel may be an ethane carrier. Effects of the invention

[0017] The fuel processing system according to the present invention and the vessel including the same can increase the operational efficiency of the demand site by re-liquefying boil-off gas, separating a certain substance from the re-liquefied boil-off gas to match the gas composition required by the demand site, and mixing the re-liquefied boil-off gas with fuel boil-off gas and supplying it to the demand site.

[0018] The effects of the present invention are not limited to those mentioned above, and other unmentioned effects will be clearly understood by those skilled in the art from the description in the claims. Brief explanation of the drawing

[0019] FIG. 1 is a conceptual diagram of a fuel processing system according to a first embodiment of the present invention. FIG. 2 is a conceptual diagram of a fuel processing system according to a second embodiment of the present invention. FIG. 3 is a conceptual diagram of a fuel processing system according to a third embodiment of the present invention. FIG. 4 is a conceptual diagram of a fuel processing system according to a fourth embodiment of the present invention. FIG. 5 is a conceptual diagram of a fuel processing system according to the fifth embodiment of the present invention. FIG. 6 is a conceptual diagram of a fuel processing system according to the sixth embodiment of the present invention. Specific details for implementing the invention

[0020] The objects, specific advantages, and novel features of the present invention will become more apparent from the following detailed description and preferred embodiments in conjunction with the accompanying drawings. It should be noted that in assigning reference numerals to the components of each drawing in this specification, identical components are assigned the same number whenever possible, even if they are shown in different drawings. Furthermore, in describing the present invention, detailed descriptions of related prior art are omitted if it is determined that such detailed descriptions would unnecessarily obscure the essence of the invention.

[0021] In addition, the attached drawings are intended only to facilitate understanding of the embodiments disclosed in this specification, and the technical concept disclosed in this specification is not limited by the attached drawings; it should be understood that all modifications, equivalents, and substitutions included within the concept and technical scope of the present invention are included.

[0022] Additionally, terms including ordinal numbers, such as first, second, etc., may be used to describe various components, but said components are not limited by said terms. These terms are used solely for the purpose of distinguishing one component from another.

[0023] In the present invention, the liquefied gas may be a substance with a boiling point lower than room temperature based on atmospheric pressure. Additionally, in this specification, the liquefied gas may be liquefied natural gas, but is not limited thereto, and may encompass all substances that have a boiling point lower than room temperature, are forcibly liquefied for storage, and have a calorific value (methane, ethane, propylene, LPG (propane, butane, etc.), hydrogen, ammonia, etc.).

[0024] In addition, it should be noted that in this specification, liquefied gas / evaporated gas is classified based on the state inside the tank, and is not necessarily limited to a liquid or gaseous state due to the name.

[0025] In the drawings of the present invention, straight lines represent flow paths through which various fluids, such as liquefied gas, fuel, refrigerant, heat transfer fluid, and purging gas, move, and can be interpreted as pipelines. Furthermore, in the present invention, pressure sensors (PT), temperature sensors (TT), flow sensors (FT), etc., may be installed at appropriate locations without limitation, and the measured values ​​from each sensor may be used in various ways without limitation for the operation of the components described below.

[0026] In addition, the present invention includes a vessel equipped with a fuel processing system described below. The vessel is a concept that includes gas carriers, merchant vessels carrying various cargo or people, FSRUs, FPSOs, bunkering vessels, offshore plants, etc.

[0027] Hereinafter, preferred embodiments of the present invention will be described in detail with reference to the attached drawings.

[0028] FIG. 1 is a conceptual diagram of a fuel processing system according to a first embodiment of the present invention.

[0029] Referring to FIG. 1, a fuel processing system (1) according to one embodiment of the present invention includes: a fuel supply unit (20) that supplies liquefied gas from a storage tank (10) to a demand place (30); and a reliquefaction unit (40) that reliquefies the evaporated gas from the storage tank (10).

[0030] The storage tank (10) can store liquefied gases such as liquefied natural gas, liquefied petroleum gas, or ammonia. One or more storage tanks (10) may be provided on board or outside the ship, and can store gases with a boiling point lower than room temperature by liquefying them and storing them in an ultra-low temperature state.

[0031] The storage tank (10) may be of a membrane type, an independent type, a pressure vessel type, etc., but is not specifically limited. However, regardless of the type, some of the liquefied gas may naturally vaporize inside the storage tank (10) to generate evaporated gas. The evaporated gas may cause a problem as it causes an increase in the internal pressure of the storage tank (10). Therefore, the evaporated gas of the storage tank (10) is discharged to the outside of the storage tank (10), and the discharged evaporated gas can be re-liquefied and returned to the storage tank (10).

[0032] The storage tank (10) may be a cargo tank for storing cargo or a fuel tank for storing fuel, but the present invention is not limited thereto.

[0033] The fuel supply unit (20) can supply liquefied gas from the storage tank (10) to the demand location (30). The fuel supply unit (20) may include a supply pump (21), a pressure pump (22), and a heater (23). The supply pump (21), the pressure pump (22), and the heater (23) may be provided in a fuel supply line (L1) connecting the storage tank (10) and the demand location (30).

[0034] The supply pump (21) can first pressurize the liquefied gas stored in the storage tank (10) and supply it to the pressure pump (22) to be described later. Specifically, the supply pump (21) is provided between the storage tank (10) and the pressure pump (22) on the fuel supply line (L1) so as to supply a sufficient amount of the liquefied gas stored in the storage tank (10) to the pressure pump (22) to prevent cavitation of the pressure pump (22).

[0035] The supply pump (21) can pressurize the liquefied gas from the storage tank (10) to within several to tens of bar, and the liquefied gas passing through the supply pump (21) can be pressurized to 1 to 25 bar.

[0036] The liquefied gas stored in the storage tank (10) is in a liquid state. At this time, the supply pump (21) can pressurize the liquefied gas discharged from the storage tank (10) to slightly increase the pressure and temperature, and the liquefied gas pressurized by the supply pump (21) may still be in a liquid state.

[0037] The supply pump (21) may be configured as a submerged type located inside the storage tank (10), or as a centrifugal type located outside at a position lower than the liquid level of the liquefied gas stored in the storage tank (10).

[0038] The pressure pump (22) can supply the liquefied gas supplied from the supply pump (21) to the heater (23) described later by pressurizing it secondarily. The pressure pump (22) can supply the liquefied gas to the pressure required by the demand place (30) and supply it to the demand place (30). For example, the pressure pump (22) can supply the liquefied gas, which is pressurized first by the supply pump (21) and has a pressure of about 6 to 8 bar, to the heater (23) by pressurizing it secondarily to a high pressure of about 200 to 400 bar.

[0039] The booster pumps (22) are provided in parallel so that if at least one of the booster pumps (22) malfunctions or shuts down, fuel can be supplied to the demand point (30) by another booster pump (22).

[0040] A heater (23) is provided on a fuel supply line (L1) and can heat high-pressure liquefied gas discharged from a pressure pump (22). Specifically, the heater (23) is provided on the fuel supply line (L1) between a demand location (30) and a pressure pump (22) to heat high-pressure liquefied gas supplied from the pressure pump (22) and supply it to the demand location (30) according to the requirements of the demand location (30). The heater (23) can heat and vaporize the liquefied gas, but the present invention is not limited thereto.

[0041] The heater (23) may use glycol water, sea water, steam, or engine exhaust gas as a heat medium for heating the liquefied gas, but the present invention is not limited thereto.

[0042] The demand source (30) may be an engine, turbine, boiler, fuel cell, burner, etc. provided in the ship, a propulsion system for propelling the ship, or a power generation system for covering the internal power load of the ship, but the present invention is not limited thereto.

[0043] The reliquefaction unit (40) can reliquefy the evaporated gas of the storage tank (10). The reliquefied evaporated gas can be delivered to the fuel supply unit (20) along the evaporated gas supply line (L2). In detail, the evaporated gas supply line (L2) can be connected to the fuel supply line (L1). More specifically, the evaporated gas supply line (L2) can be connected upstream of the pressure pump (22).

[0045] FIG. 2 is a conceptual diagram of a fuel processing system according to a second embodiment of the present invention.

[0046] In the following, content that overlaps with what is described in Figure 1 may be omitted.

[0047] Referring to FIG. 2, a fuel processing system (1) according to a second embodiment of the present invention comprises: a fuel supply unit (20) that supplies liquefied gas from a storage tank (10) to a demand place (30); and a reliquefaction unit (40) that reliquefies the evaporated gas from the storage tank (10).

[0048] The re-liquefaction unit (40) can re-liquefy the evaporated gas discharged from the storage tank (10). The re-liquefaction unit (40) includes a compression unit (41), a cooling unit (42), a condensation unit (43), a receiver (44), and a heat exchange unit (45).

[0049] The re-liquefaction unit (40) and the storage tank (10) can be connected to a re-liquefaction line (L3). A compression unit (41), a condensation unit (43), etc., can be provided on the re-liquefaction line (L3).

[0050] The compression unit (41) can compress the evaporated gas generated in the storage tank (10). The compression unit (41) may be centrifugal or reciprocating, and may be provided in a multi-stage configuration including multiple compression stages. Additionally, the compression unit (41) may be provided in parallel for backup or load sharing.

[0051] The compression unit (41) can compress the evaporated gas flowing in at approximately 1 bar to 10 to 100 bar, and when the evaporated gas is compressed by the compression unit (41), the boiling point of the evaporated gas may be raised. Therefore, the compressed evaporated gas can be in a state where it can be liquefied without being cooled to the boiling point at atmospheric pressure.

[0052] The compression section (41) may be composed of three stages, and the evaporated gas can be compressed to approximately 4 bar in the first compression section (41a), approximately 10 bar in the second compression section (41b), and approximately 20 to 30 bar in the third compression section (41c). Of course, the pressure of the evaporated gas compressed by the compression section (41) and the number of stages of the compression section (41) are not particularly limited.

[0053] In the re-liquefaction line (L3), a plurality of compression stages are provided in series so that the compression section (41) can be configured as a multi-stage compressor, and a heat exchanger (45) can be provided in an intermediate stage between the compression stages on the re-liquefaction line (L3). At least a portion of the evaporated gas discharged from the compression section (41) can be transferred to the heat exchanger (45). The heat exchanger (45) can control the temperature of the evaporated gas transferred from the compression section (41). For example, the heat exchanger (45) can cool the evaporated gas transferred from the compression section (41).

[0054] The heat exchanger (45) may be a cooling facility that uses condensed evaporated gas or depressurized evaporated gas as a refrigerant without a separate refrigerant. For example, the heat exchanger (45) may be an intercooler.

[0055] The heat exchanger (45) can implement cooling at the intermediate stage of the compression unit (41) composed of multiple units. For example, the heat exchanger (45) can cool low-pressure evaporated gas or medium-pressure evaporated gas introduced from the compression unit (41).

[0056] The above heat exchanger (45) may be composed of multiple units. For example, the heat exchanger (45) may include a second heat exchanger (not shown) that controls the temperature of relatively low-pressure evaporated gas exiting the first compression unit (41a) and a first heat exchanger (not shown) that controls the temperature of relatively medium-pressure evaporated gas exiting the second compression unit (41b). Evaporated gas whose temperature is controlled in the second heat exchanger may be transferred to the second compression unit (41b), and evaporated gas whose temperature is controlled in the first heat exchanger may be transferred to the third compression unit (41c). High-pressure evaporated gas compressed in the third compression unit (41c) may be transferred to the condenser (43). However, the present invention is not limited to the number of the heat exchangers (45).

[0057] Of course, depending on variables such as the internal pressure of the heat exchanger (45) and the temperature of the evaporated gas, the evaporated gas may be controlled to bypass the heat exchanger (45), and the present invention is not limited thereto.

[0058] The condenser (43) cools the evaporated gas compressed in the compressor (41) to re-liquefy at least a portion of the evaporated gas. It should be noted that while the condenser (43) can re-liquefy the evaporated gas, it does not exclude situations where re-liquefying of the evaporated gas does not occur at all or only a portion of the evaporated gas is re-liquefied due to various factors during actual operation. For example, if substances with different boiling points are mixed in the evaporated gas, some components with relatively lower boiling points may not be re-liquefied.

[0059] The condenser (43) is provided downstream of the multi-stage compression section (41) and can cool the evaporated gas using various refrigerants that are not limited (e.g., seawater, fresh water, glycol water, nitrogen, LNG, LPG, propane, R134a, CO2, etc.). A single refrigerant or a mixed refrigerant may be used as the refrigerant.

[0060] The condenser (43) may lower the temperature of the evaporated gas compressed in the compressor (41), but may not lower the temperature of the evaporated gas to the boiling point of the evaporated gas at atmospheric pressure. This is because the boiling point of the evaporated gas rises as the evaporated gas is compressed by the compressor (41). However, the condenser (43) may adjust the cooling temperature of the evaporated gas by taking into account the pressure of the evaporated gas discharged from the final stage (e.g., the third compressor (41c)).

[0061] A cooling section (42) may be provided upstream of the condensation section (43). The cooling section (42) may cool the evaporated gas compressed in the compression section (41). The cooling section (42) may pre-cool the evaporated gas upstream of the condensation section (43). The cooling section (42) may pre-cool the evaporated gas with seawater, and the condensation section (43) may condense the evaporated gas with a refrigerant.

[0062] The evaporative gas can be sufficiently condensed in the cooling section (42), in which case the evaporative gas can bypass the condensation section (43). Additionally, the evaporative gas can be sufficiently condensed in the cooling section (42) or the condensation section (43), and the cooling section (42) or the condensation section (43) may be omitted. However, the present invention is not limited thereto.

[0063] The above condensation unit (43) can control the temperature of the evaporated gas delivered along the condensation line (L4) using the refrigerant delivered along the refrigerant line (L5). The refrigerant may be a mixed refrigerant. The mixed refrigerant refers to a mixed refrigerant (MR), which is a refrigerant mixed with methane, propane, nitrogen, etc., and may be a substance already widely known in the field of re-liquefaction. The mixing ratio may vary depending on the required pressure of the consumer (30) consuming the liquefied evaporated gas, the type and size of the storage tank (10), etc., and is not separately limited in the present invention.

[0064] The above refrigerant line (L5) may include a refrigerant compressor (431) that compresses the refrigerant discharged from the condenser (43). The refrigerant compressor (431) may be centrifugal or reciprocating, and may be provided in a multi-stage configuration including multiple compression stages. Additionally, the refrigerant compressor (431) may be provided in parallel for backup or load sharing. When the refrigerant is compressed by the refrigerant compressor (431), the boiling point of the refrigerant may be raised.

[0065] The refrigerant passing through the refrigerant compressor (431) can be transferred to a refrigerant heat exchanger (432). The temperature of the refrigerant passing through the refrigerant compressor (431) can be controlled in the refrigerant heat exchanger (432). At least a portion of the refrigerant can be condensed in the refrigerant heat exchanger (432). The refrigerant heat exchanger (432) can condense the refrigerant using seawater or fresh water, etc.

[0066] The refrigerant condensed in the above refrigerant heat exchanger (432) can be transferred to a refrigerant separator (433). The refrigerant separator (433) can separate the refrigerant into a gaseous refrigerant and a liquid refrigerant. At least some of the refrigerant separated in the refrigerant separator (433) can be transferred to a refrigerant cooler (434).

[0067] The above refrigerant compressor (431) may be composed of a plurality of compression stages, and a refrigerant cooler (434) may be provided between the plurality of compression stages. The above refrigerant cooler (434) may be a cooling facility that cools the refrigerant compressed in the above refrigerant compressor (431) with the refrigerant condensed in the above refrigerant heat exchanger (432) without a separate refrigerant.

[0068] A receiver (44) may be provided downstream of the condenser (43). The evaporated gas condensed in the condenser (43) may be transferred to the receiver (44). The receiver (44) may temporarily store the liquefied evaporated gas from the condenser (43). The receiver (44) may transfer the condensed evaporated gas to a storage tank (10). The receiver (44) may be connected to the storage tank (10) along a re-liquefaction line (L3) passing through a heat exchanger (45).

[0069] The receiver (44) may have a gas-liquid separation function. The receiver (44) may transfer liquefied evaporated gas among the evaporated gas discharged from the condenser (43) to the heat exchanger (45) or the storage tank (10). The receiver (44) may contain evaporated gas (non-condensable gas), etc. that is not liquefied, and may prevent the vaporization of the evaporated gas by maintaining a certain level of internal pressure. In addition, evaporated gas (non-condensable gas), etc. that is not liquefied may be discharged to the outside. The receiver (44) may be omitted. In this case, the evaporated gas cooled in the condenser (43) may be transferred to the heat exchanger (45) or the storage tank (10).

[0070] The heat exchanger (45) has a space for receiving evaporated gas that has been depressurized by a pressure reducing valve. The evaporated gas condensed in the condenser (43) can be transferred to the heat exchanger (45) along a re-liquefaction line (L3) and a branch line (not shown) branching from the re-liquefaction line (L3). The heat exchanger (45) has a space inside, and the evaporated gas that has been depressurized by a pressure reducing valve provided in the branch line can be filled into the space. The pressure reducing valve can be a Joule-Thomson valve or an expander, etc., and can depressurize and cool the evaporated gas (Joule-Thomson effect), thereby subcooling or liquefying the evaporated gas.

[0071] At least a portion of the above re-liquefaction line (L3) passes through the interior of the heat exchanger (45), and the evaporated gas passing through the interior of the heat exchanger (45) along the above re-liquefaction line (L3) can be heat exchanged with the evaporated gas filling the interior of the heat exchanger (45).

[0072] The above heat exchanger (45) can enable stable liquefaction through non-contact heat exchange between evaporated gases without a separate refrigerant. In this respect, the heat exchanger (45) can be referred to as a heat exchanger, and for example, can be viewed as a bath-type heat exchanger. At this time, the cooling passages (L31b, L32b) can be provided in a coil shape inside the liquefied evaporated gas to improve liquefaction efficiency.

[0073] Additionally, the fuel processing system (1) comprises: a pressure reduction unit (60) for reducing the pressure of the evaporated gas re-liquefied in the re-liquefaction unit (40); and a separation unit (50) for separating the evaporated gas reduced in pressure in the pressure reduction unit (60) into a gaseous substance and a liquid substance.

[0074] In detail, the evaporated gas reliquefied in the reliquefaction unit (40) can be supplied to a demand location (30) along the evaporated gas supply line (L2). One end of the evaporated gas supply line (L2) may be branched off from the reliquefaction line (L3) downstream of the receiver (44), and the other end may be connected to the separation unit (50). A pressure reduction unit (60) may be provided on the evaporated gas supply line (L2).

[0075] A storage tank (10) may store liquefied gas. The liquefied gas may contain hydrocarbon substances. Specifically, the liquefied gas may contain multiple hydrocarbon substances. The liquefied gas may contain multiple hydrocarbon substances with different boiling points. For example, the liquefied gas may contain methane and ethane. Like the liquefied gas, the evaporated gas may also contain multiple hydrocarbon substances with different boiling points.

[0076] However, the liquefied gas of the storage tank (10) may contain a hydrocarbon material with a relatively high boiling point in a higher proportion, and the evaporated gas of the storage tank (10) may contain a hydrocarbon material with a relatively low boiling point in a higher proportion. For example, the liquefied gas of the storage tank (10) may contain ethane with a relatively high boiling point in a higher proportion, and the evaporated gas of the storage tank (10) may contain methane with a relatively low boiling point in a higher proportion.

[0077] The above-described pressure reduction unit (60) lowers the pressure of the re-liquefied evaporated gas to control the ratio of methane contained in the liquid substance in the saturated state to a value below a certain value, and the above-described separation unit (50) separates the gaseous substance containing methane from the reduced-pressure evaporated gas and delivers it to the above-described demand location (30). The above-described pressure reduction unit (60) may be a pressure reduction valve or a pressure reduction device, but the present invention is not limited thereto.

[0078] In this specification, controlling the ratio (content) of methane can be understood as controlling the concentration of methane.

[0079] Specifically, the pressure reduction unit (60) can reduce the pressure of the re-liquefied evaporated gas. In detail, the pressure reduction unit (60) can reduce the pressure of the re-liquefied evaporated gas to control the pressure of the evaporated gas to a value below a certain value. For example, the pressure reduction unit (60) can lower the pressure of the re-liquefied evaporated gas to the required pressure of the pressure pump (22).

[0080] The above separation unit (50) can separate hydrocarbon substances with a relatively high boiling point and hydrocarbon substances with a relatively low boiling point from the re-liquefied evaporated gas. Specifically, the above separation unit (50) can separate substances with relatively high volatility into a gaseous phase and separate the remaining substances into a liquid phase.

[0081] In detail, the pressure reduction unit (60) can reduce the pressure of the re-liquefied evaporated gas to evaporate a relatively volatile substance. The evaporated gas reduced in pressure at the pressure reduction unit (60) can be transferred to the separation unit (50) in a state where the highly volatile substance has evaporated or vaporized. In the separation unit (50), the evaporated gas in a gaseous state containing a relatively large amount of the highly volatile substance and the re-liquefied evaporated gas can be separated.

[0082] In the following description, highly volatile substances are described as methane and relatively low volatile substances are described as ethane, but the present invention is not limited thereto.

[0083] The above separation unit (50) can reduce the concentration (ratio) of methane contained in the re-liquefied evaporated gas. Specifically, the above separation unit (50) can reduce the concentration of methane contained in the re-liquefied evaporated gas to a concentration lower than the required concentration of the user (30). For example, the evaporated gas re-liquefied in the above re-liquefaction unit (40) may contain about 20 mol% or more of methane, and the above separation unit (50) can reduce the concentration of methane contained in the re-liquefied evaporated gas to about 15 mol% or less, which is the required concentration of the user (30).

[0084] The re-liquefied evaporated gas separated in the separation unit (50) may contain methane with a concentration below a certain level and high volatility methane separated. Specifically, the demand source (30) requires that the fuel contain methane at a concentration below a certain level, and the re-liquefied evaporated gas separated in the separation unit (50) may contain methane at a lower concentration than the methane concentration required by the demand source (30).

[0085] For example, the re-liquefied evaporated gas separated in the separation unit (50) may contain 15 mol% or less of methane. Preferably, the re-liquefied evaporated gas separated in the separation unit (50) may contain 10 mol% or less of methane.

[0086] Additionally, the liquefied gas supplied to the above-mentioned demand location (30) may contain methane at a ratio of less than a certain amount. The re-liquefied evaporated gas separated in the separation unit (50) and the mixed fuel delivered from the supply pump (21) are supplied to the above-mentioned demand location (30), and the mixed fuel supplied to the above-mentioned demand location (30) may contain methane at a lower concentration than the methane concentration required by the demand location (30).

[0087] For example, the mixed fuel may contain 15 mol% or less of methane. Preferably, the mixed fuel may contain 10 mol% or less of methane.

[0088] The amount of fuel supplied by the supply pump (21) can be determined according to the concentration of methane contained in the evaporated gas delivered from the separation unit (50). For example, the concentration of methane contained in the evaporated gas delivered from the separation unit (50) may be higher than the concentration of methane required by the demand location (30). In this case, the supply pump (21) can increase the amount of fuel supplied to the demand location (30). Accordingly, the concentration of methane contained in the fuel supplied to the demand location (30) can be maintained below a certain value.

[0089] The gaseous evaporated gas separated in the separation unit (50) can be transferred to a storage tank (10) along the first evaporated gas supply line (L21). Specifically, the gaseous evaporated gas separated in the separation unit (50) can be recovered to a cargo tank.

[0090] The fuel supply unit (20) includes a pressure pump (22) that pressurizes liquefied gas to the required pressure of the demand location (30); and the liquid material separated in the separation unit (50) can be delivered upstream of the pressure pump (22).

[0091] The re-liquefied evaporated gas separated in the separation unit (50) can be delivered to the fuel supply line (L1) along the second evaporated gas supply line (L22). Specifically, the re-liquefied evaporated gas separated in the separation unit (50) can be delivered between the supply pump (21) and the pressurizing pump (22) along the second evaporated gas supply line (L22).

[0092] The fuel supply unit (20) can mix the liquefied gas of the storage tank (10) with the evaporated gas depressurized in the depressurization unit (60) and supply it to the demand location (30). Specifically, the evaporated gas delivered from the separation unit (50) and the fuel delivered from the supply pump (21) can be mixed upstream of the pressure pump (22). The mixed fuel can pass through the heater (23) and be used at the demand location (30).

[0093] The supply pump (21) can supply fuel from the storage tank (10) to the demand location (30), and the supply pump (21) can adjust the flow rate of fuel supplied to the demand location (30) by taking into account the flow rate of the re-liquefied evaporated gas supplied from the separation unit (50). For example, if the amount of re-liquefied evaporated gas supplied from the separation unit (50) is insufficient compared to the fuel requirement of the demand location (30), the supply pump (21) can supply fuel for the shortfall.

[0095] FIG. 3 is a conceptual diagram of a fuel processing system according to a third embodiment of the present invention.

[0096] Referring to FIG. 3, the system includes: a fuel supply unit (20) that supplies liquefied gas from a storage tank (10) to a demand location (30); a reliquefaction unit (40) that reliquefies the evaporated gas from the storage tank (10); and a mixer (70) that mixes the liquefied gas from the storage tank (10) with the evaporated gas reliquefied in the reliquefaction unit (40) to adjust the ratio of methane contained in the liquefied gas supplied to the demand location (30) to a value below a certain value.

[0097] The system includes a pressure reduction unit (60) that reduces the pressure of the evaporated gas re-liquefied in the re-liquefaction unit (40) and delivers it to the mixer (70); and the pressure reduction unit (60) can lower the pressure of the evaporated gas re-liquefied to control the ratio of methane contained in the liquid substance in a saturated state to a value below a certain value.

[0098] The above-described pressure reduction unit (60) can reduce the concentration (ratio) of methane contained in the re-liquefied evaporated gas. Specifically, the above-described pressure reduction unit (60) can reduce the concentration of methane contained in the re-liquefied evaporated gas to a concentration lower than the required concentration of the user (30). For example, the evaporated gas re-liquefied in the above-described re-liquefaction unit (40) may contain about 20 mol% or more of methane, and the above-described pressure reduction unit (60) can reduce the concentration of methane contained in the re-liquefied evaporated gas to about 15 mol% or less, which is the required concentration of the user (30).

[0099] The demand source (30) requires that the fuel contain methane at a concentration below a certain level, and the pressure reduction unit (60) can adjust the concentration of methane to be lower than the concentration of methane required by the demand source (30).

[0100] For example, the evaporated gas from which methane has been separated by the pressure reduction unit (60) may contain 15 mol% or less of methane. Preferably, the evaporated gas from which methane has been separated by the pressure reduction unit (60) may contain 10 mol% or less of methane.

[0101] The above mixer (70) can mix the liquefied gas of the storage tank (10) and the evaporated gas reliquefied in the reliquefaction unit (40). At this time, the liquefied gas of the storage tank (10) and the evaporated gas reliquefied in the reliquefaction unit (40) are mixed in the mixer (70), and the ratio of methane contained in the total mixed fuel can be adjusted.

[0102] The evaporated gas from which methane has been separated by the above-mentioned pressure reduction unit (60) is mixed with fuel delivered from the above-mentioned supply pump (21) in the above-mentioned mixer (70), and the mixed fuel can be supplied to the above-mentioned demand location (30).

[0103] It is preferable that the mixed fuel supplied to the above-mentioned demand source (30) contains methane at a certain ratio or lower. The mixed fuel supplied to the above-mentioned demand source (30) may contain methane at a lower concentration than the methane concentration required by the demand source (30). For example, the mixed fuel may contain 15 mol% or less of methane. Preferably, the mixed fuel may contain 10 mol% or less of methane.

[0104] The amount of fuel supplied by the supply pump (21) can be determined according to the concentration of methane contained in the evaporated gas delivered from the pressure reduction unit (60). For example, the concentration of methane contained in the evaporated gas delivered from the pressure reduction unit (60) may be higher than the concentration of methane required by the demand location (30). In this case, the supply pump (21) can increase the amount of fuel supplied to the demand location (30). Accordingly, the concentration of methane contained in the fuel supplied to the demand location (30) can be maintained below a certain value.

[0105] Here, the fuel supplied by the supply pump (21) can be supplied to the mixer (70) as fuel containing 5.0 mol% or less of methane. Preferably, the fuel supplied by the supply pump (21) can be supplied to the mixer (70) as fuel containing 1.0 mol% or less of methane.

[0106] In the mixer (70), the evaporated gas delivered from the pressure reduction unit (60) and the fuel supplied by the supply pump (21) can be mixed. The mixed fuel mixed in the mixer (70) may contain methane at a lower concentration than the methane concentration required by the demand source (30). For example, the mixed fuel may contain 15 mol% or less of methane. Preferably, the mixed fuel may contain 10 mol% or less of methane.

[0107] The fuel supply unit (20) includes a pressure pump (22) that pressurizes liquefied gas to the required pressure of the demand location (30); and the mixer (70) is provided upstream of the pressure pump (22) and can deliver the mixed liquefied gas to the pressure pump (22).

[0108] The above pressure reduction unit (60) can reduce the pressure of the evaporated gas supplied to the mixer (70). At this time, the liquefied gas mixed in the mixer (70) can meet the required pressure of the pressure pump (22).

[0110] Below, the mixer (70) and the configuration related to the mixer (70) are described. Depending on the phase of the evaporated gas delivered from the pressure reduction unit (60), the configuration related to the mixer (70) may be added.

[0111] FIG. 4 is a conceptual diagram of a fuel processing system according to a fourth embodiment of the present invention. FIG. 5 is a conceptual diagram of a fuel processing system according to a fifth embodiment of the present invention. FIG. 6 is a conceptual diagram of a fuel processing system according to a sixth embodiment of the present invention.

[0112] Referring to FIG. 4, it may include a buffer tank (80) for storing the liquefied gas mixed in the mixer (70). When the evaporated gas delivered from the pressure reduction unit (60) is liquid, the evaporated gas delivered from the pressure reduction unit (60) and the fuel delivered from the supply pump (21) can be mixed in the mixer (70). The mixed fuel can be supplied to a demand location (30) by a pressure pump (22).

[0113] Referring to FIG. 5, the mixer (70) can be accommodated in a buffer tank (80). When the evaporated gas delivered from the depressurization unit (60) contains some gas, the evaporated gas re-liquefied in the re-liquefaction unit (40) and the fuel delivered from the supply pump (21) are mixed in the mixer (70), and the buffer tank (80) can store the mixed fuel.

[0114] The above mixer (70) can agitate the evaporated gas delivered from the pressure reduction unit (60) and the fuel delivered from the supply pump (21). The above mixer (70) may have a shape that extends in the vertical direction inside the buffer tank (80). The above mixer (70) may have a part submerged in a liquid material.

[0115] The evaporated gas delivered from the above-mentioned pressure reduction unit (60) may be delivered to the upper part of the mixer (70), and the fuel delivered from the above-mentioned supply pump (21) may be delivered to the lower part of the mixer (70), but the present invention is not limited thereto.

[0116] The line through which the evaporated gas is transferred from the pressure reduction unit (60) to the mixer (70) may be positioned higher than the line through which the gas is transferred from the supply pump (21) to the mixer (70). For example, the supply pump (21) may be connected to the part of the mixer (70) that is submerged in liquid material, and the pressure reduction unit (60) may be connected above a certain height of the mixer (70).

[0117] In the process of stirring the re-liquefied evaporated gas delivered from the pressure reduction unit (60) and the fuel delivered from the supply pump (21) in the above mixer (70), highly volatile methane can be evaporated into gas.

[0118] During stirring of the above mixer (70), some of the gas inside the buffer tank (80) may be discharged to the outside. Therefore, since the pressure inside the buffer tank (80) is lowered, the amount of methane evaporated from the mixer (70) may increase.

[0119] Additionally, the mixer (70) may be connected to the buffer tank (80) via piping, and the present invention is not limited thereto.

[0120] The fuel supply amount of the supply pump (21) can be adjusted according to the level of the mixed fuel stored in the buffer tank (80). For example, if the level of the mixed fuel stored in the buffer tank (80) drops below a certain value, the fuel supply amount of the supply pump (21) may increase. Conversely, if the level of the mixed fuel stored in the buffer tank (80) rises above a certain value, the fuel supply amount of the supply pump (21) may decrease. The buffer tank (80) may maintain a certain level.

[0121] The mixed fuel in the buffer tank (80) can be transferred to the pressure pump (22). Since the mixed fuel is stored in the buffer tank (80), the supply of fuel to the pressure pump (22) can be maintained stably. In addition, fuel in a liquid state can be supplied to the pressure pump (22), and the pressure of the fuel supplied to the pressure pump (22) can be maintained stably.

[0122] Of course, the mixed fuel stored in the buffer tank (80) may contain methane at a lower concentration than the methane concentration required by the demand source (30). For example, the mixed fuel may contain 15 mol% or less of methane. Preferably, the mixed fuel may contain 10 mol% or less of methane.

[0123] Referring to FIG. 6, the apparatus may include a separation unit (50) provided between the pressure reduction unit (60) and the mixer (70) to separate gaseous substances containing methane from the evaporated gas re-liquefied in the re-liquefaction unit (40) and to deliver the evaporated gas to the demand location (30).

[0124] The above mixer (70) may be housed inside the buffer tank (80), and the separation unit (50) may be provided upstream of the buffer tank (80).

[0125] The separation unit (50) can separate the evaporated gas depressurized in the depressurization unit (60) into a gaseous substance containing a high proportion of methane and a liquid substance containing a relatively low proportion of methane. Here, the liquid substance can be transferred to a buffer tank (80). The separated gaseous substance can be transferred to the mixer (70).

[0126] The above mixer (70) may have a shape that extends in the vertical direction inside the buffer tank (80). The above separation part (50) may be connected to the upper part of the mixer (70) and the lower part of the buffer tank (80), respectively. A gaseous substance may be delivered along the upper line connected to the upper part of the mixer (70), and a liquid substance may be delivered along the lower line connected to the lower part of the buffer tank (80).

[0127] The line through which the evaporated gas is transferred from the separation unit (50) to the mixer (70) may be positioned higher than the line through which the gas is transferred from the supply pump (21) to the mixer (70). For example, both the upper and lower lines connecting the separation unit (50) to the mixer (70) may be positioned higher than the line through which the gas is transferred from the supply pump (21) to the mixer (70). The line connecting the supply pump (21) to the mixer (70) may be connected to the part of the mixer (70) that is submerged in liquid material.

[0128] The fuel delivered from the supply pump (21) may be delivered to the lower part of the mixer (70), but the present invention is not limited thereto.

[0129] As in FIG. 5, the fuel supply amount of the supply pump (21) can be adjusted according to the level of the mixed fuel stored in the buffer tank (80). For example, if the level of the mixed fuel stored in the buffer tank (80) drops below a certain value, the fuel supply amount of the supply pump (21) may increase. Conversely, if the level of the mixed fuel stored in the buffer tank (80) rises above a certain value, the fuel supply amount of the supply pump (21) may decrease. The buffer tank (80) may be maintained at a certain level.

[0131] In this way, a fuel processing system according to one embodiment of the present invention can re-liquefy evaporated gas in a re-liquefaction unit and reduce the proportion of volatile substances contained in the re-liquefied evaporated gas. Accordingly, it can satisfy the requirements of the end users regarding volatile substances.

[0132] In detail, in the case of an ethane carrier, it is difficult to directly supply the reliquefied boil-off gas to the engine because the reliquefied boil-off gas has a high methane content, but the present invention can reduce the proportion of methane in the reliquefied boil-off gas and can directly supply the reliquefied boil-off gas to the engine.

[0133] In addition to the embodiments described above, the present invention encompasses all embodiments resulting from a combination of the above embodiments and known technology.

[0134] Although the present invention has been described in detail through specific embodiments, this is for the purpose of specifically explaining the invention, and the invention is not limited thereto. It will be apparent that modifications or improvements can be made by those skilled in the art within the technical scope of the invention.

[0135] All simple variations or modifications of the present invention fall within the scope of the present invention, and the specific scope of protection of the present invention will be clarified by the appended claims. Explanation of the symbols

[0136] 1: Fuel processing system 10: Storage tank 20: Fuel supply unit 21: Supply pump 22: Pressure pump 23: Heater 30: Demand source 40: Re-liquefaction unit 41: Compression section 42: Cooling section 43: Condenser 431: Refrigerant compressor 432: Refrigerant heat exchanger 433: Refrigerant separator 434: Refrigerant cooler 44: Receiver 45: Heat exchange section 20a: First compression section 20b: Second compression section 20c: Third compression section 30: Condenser 40: Receiver 50: Heat exchange section 60: Pressure reduction section 70: Mixer 80: Buffer tank L1: Fuel supply line L2: Evaporative Gas Supply Line L21: 1st Evaporative Gas Supply Line L22: Second Evaporative Gas Supply Line L3: Re-liquefaction line L4: Condensation line L5: Refrigerant line

Claims

Claim 1 A fuel processing system comprising: a fuel supply unit that supplies liquefied gas from a storage tank to a demand location; a reliquefaction unit that reliquefies the evaporated gas from the storage tank; a pressure reduction unit that reduces the pressure of the evaporated gas reliquefied in the reliquefaction unit; and a separation unit that separates the evaporated gas reduced in pressure in the pressure reduction unit into a gaseous substance and a liquid substance; wherein the pressure reduction unit lowers the pressure of the reliquefied evaporated gas to control the ratio of methane contained in the liquid substance in a saturated state to a value below a certain value, and the separation unit separates the gaseous substance containing methane from the reduced-pressure evaporated gas and then delivers it to the demand location. Claim 2 A fuel processing system according to claim 1, wherein the fuel supply unit comprises a pressure pump that pressurizes liquefied gas to the required pressure of the demand location, and the liquid material separated in the separation unit is transferred upstream of the pressure pump. Claim 3 A fuel processing system according to claim 1, wherein the fuel supply unit mixes the liquefied gas of the storage tank with the evaporated gas depressurized in the depressurization unit and supplies it to the demand location. Claim 4 In paragraph 3, the liquefied gas supplied to the above-mentioned demand source is a fuel processing system containing methane at a certain ratio or less. Claim 5 A fuel processing system according to claim 1, wherein the pressure reduction unit controls the ratio of methane contained in the liquid material to a ratio of methane required by the demand source or lower. Claim 6 In claim 5, the above-mentioned pressure reduction unit controls the ratio of methane contained in the liquid material to 15 mol% or less, a fuel processing system. Claim 7 A vessel comprising the fuel processing system of any one of paragraphs 1 to 6. Claim 8 In Paragraph 7, a vessel that is an ethane carrier.

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