JP2019210976A - Gas supply unit and mixed combustion power generation device - Google Patents

Abstract

To provide a gas supply unit that can efficiently liquefy boil-off gas of LNG.SOLUTION: A gas supply unit comprises: an LNG tank for storing liquefied natural gas; an LNG path through which the liquefied natural gas flowing out of the LNG tank flows; an LNG vaporizer for vaporizing the liquefied natural gas flowing in from the LNG path; an LH2 tank for storing liquefied hydrogen; an LH2 path through which the liquefied hydrogen flowing out of the LH2 tank flows; an LH2 vaporizer for vaporizing the liquefied hydrogen flowing in from the LH2 path; a BOG path into which boil-off gas generated in at least one of the LNG tank and the LNG path flows; a liquefier for cooling and liquefying the boil-off gas by exchanging heat between the liquefied hydrogen flowing in from the LH2 path and the boil-off gas flowing in from the BOG path; and a return path connected to the liquefier, and for returning the boil-off gas liquefied in the liquefier to the LNG tank.SELECTED DRAWING: Figure 1

Description

  The present invention relates to a gas supply unit and a mixed combustion power generation apparatus including the gas supply unit.

  Conventionally, as disclosed in Patent Document 1, a gas supply unit that vaporizes liquefied natural gas (LNG) and supplies the generated natural gas (NG) to a predetermined demand destination is known. ing. This gas supply unit is used to supply natural gas as a fuel to a combustor, for example, in a thermal power generation process.

  Patent Document 1 discloses a processing system in which LNG flowing out from an LNG storage tank is sent to a vaporizer by a pump, and NG generated by the vaporizer is supplied to a demand destination. In this processing system, boil-off gas (BOG) generated by evaporation of LNG in the LNG storage tank is liquefied by heat exchange with liquid nitrogen, and the liquefied BOG (LNG) is returned to the LNG storage tank. It is configured. Patent Document 2 also discloses a gas reliquefaction device that liquefies BOG generated in a liquefied gas storage tank by heat exchange with liquid nitrogen and returns the liquefied gas to the tank.

JP 2002-295799 A JP 2009-204080 A

  Patent Documents 1 and 2 liquefy the boil-off gas generated in the LNG storage tank or the liquefied gas storage tank using the cold heat of liquid nitrogen, and return it to the LNG storage tank or the liquefied gas storage tank. There is room for improvement in terms of efficiency.

  The present invention has been made in view of the above problems, and an object of the present invention is to provide a gas supply unit capable of efficiently liquefying LNG boil-off gas and a co-fired power generation apparatus including the gas supply unit. .

  A gas supply unit according to an aspect of the present invention includes an LNG tank that stores liquefied natural gas, an LNG path through which the liquefied natural gas that has flowed out of the LNG tank flows, the LNG path, and an inflow from the LNG path An LNG vaporizer that vaporizes liquefied natural gas, an LH2 tank that stores liquid hydrogen (also referred to as “LH2”), an LH2 path through which liquid hydrogen that has flowed out of the LH2 tank flows, and the LH2 path, the LH2 An LH2 vaporizer that vaporizes liquid hydrogen flowing in from the path, a BOG path into which boil-off gas generated by evaporation of liquefied natural gas in at least one of the LNG tank and the LNG path, and the BOG path and the LH2 Connected to the path, from the liquid hydrogen flowing in from the LH2 path and the BOG path A liquefier that cools and liquefies the boil-off gas by heat exchange with the boil-off gas that enters, and a return path that is connected to the liquefier and returns the boil-off gas liquefied by the liquefier to the LNG tank. Yes.

  In this gas supply unit, the liquefied natural gas flowing out from the LNG tank is vaporized by the LNG vaporizer, and the liquid hydrogen flowing out from the LH2 tank is vaporized by the LH2 vaporizer, and the natural gas and hydrogen gas are supplied to a predetermined demand destination. can do. Here, when the LNG boil-off gas is cooled and liquefied in the liquefier, the cold heat of the liquid hydrogen flowing out from the LH2 tank can be used. For this reason, the boil-off gas of LNG can be liquefied efficiently compared with the case where liquid nitrogen is used as a cold heat source conventionally.

  The gas supply unit further includes a bypass path connected to the LH2 path so as to bypass the liquefier, and a bypass valve that controls inflow of liquid hydrogen from the LH2 path to the bypass path. Also good.

  Liquid hydrogen is a cryogenic liquid whose temperature is lower than that of liquid nitrogen and well below the freezing point of methane, which is the main component of natural gas. For this reason, for example, when the flow rate of liquid hydrogen flowing into the liquefier is excessive with respect to the flow rate of the boil-off gas, the boil-off gas is excessively cooled, and as a result, the LNG freezes in the flow path of the liquefier. Sometimes. On the other hand, according to the above configuration, even when the flow rate of liquid hydrogen is excessive with respect to the flow rate of boil-off gas, the amount of liquid hydrogen flowing into the liquefier can be controlled using the bypass path and the bypass valve. Therefore, it is possible to prevent LNG from freezing in the flow path of the liquefier.

  In the gas supply unit, the liquefier may have a flow path through which boil-off gas flowing from the BOG path flows. The gas supply unit includes a differential pressure detection unit that detects a differential pressure before and after the flow path, an outlet temperature detection unit that detects the temperature of the liquefied natural gas flowing out from the flow path, and a liquefaction that detects the temperature of the liquefier. At least one of a vessel temperature detection unit, an inlet side flow rate detection unit that detects the flow rate of boil-off gas on the inlet side of the flow channel, and an outlet side flow rate detection unit that detects the flow rate of liquefied natural gas on the outlet side of the flow channel And a control unit that controls the bypass valve based on a detection result by the detection mechanism.

  According to this configuration, the bypass valve can be automatically controlled based on various detection results for detecting freezing of LNG in the flow path of the liquefier. For this reason, the amount of liquid hydrogen flowing into the liquefier can be easily controlled as compared with the case where the bypass valve is manually controlled.

  In the gas supply unit, the LH2 path and the BOG path may be branched into a plurality of paths. The plurality of liquefiers may be arranged in parallel in the plurality of paths. The gas supply unit further includes an LH2 switching valve that switches inflow of liquid hydrogen to each of the plurality of liquefiers, and a BOG switching valve that switches inflow of boil-off gas to each of the plurality of liquefiers. May be.

  According to this configuration, even when the flow path is blocked by freezing of LNG in one liquefier, continuous operation is possible by switching to use of another liquefier.

  The gas supply unit may further include a melting mechanism for melting the liquefied natural gas frozen in the flow path in which the boil-off gas flowing from the BOG path flows in the liquefier.

  According to this configuration, even when the flow path is blocked by freezing of LNG in the liquefier, the liquefier can be reused by melting it.

  In the gas supply unit, the melting mechanism may be configured to return a part of the hydrogen gas vaporized by the LH2 vaporizer to the upstream side of the liquefier in the LH2 path.

  According to this configuration, a part of the hydrogen gas generated by the LH2 vaporizer can be used as a heat source for melting frozen LNG. Therefore, energy can be saved as compared with the case of using another heat source that requires energy.

  A co-fired power generation apparatus according to another aspect of the present invention includes the gas supply unit according to one aspect of the present invention, and a co-fired power generation unit that generates power using natural gas and hydrogen gas supplied from the gas supply unit as fuel. ing.

  Since this mixed combustion power generation device includes the gas supply unit according to one aspect of the present invention, the boil-off gas of LNG can be efficiently liquefied. For this reason, it is possible to reduce the amount of boil-off gas that is boosted by the compressor and sent to the co-firing power generation unit. Therefore, energy saving can be achieved by reducing the power of the compressor.

  As is apparent from the above description, according to the present invention, it is possible to provide a gas supply unit capable of efficiently liquefying LNG boil-off gas and a co-fired power generation apparatus including the gas supply unit.

It is a figure which shows typically the structure of the gas supply unit which concerns on Embodiment 1 of this invention, and a co-firing power generation apparatus. It is a figure which shows typically the structure of the gas supply unit and mixed combustion electric power generating apparatus which concern on Embodiment 2 of this invention. It is a flowchart for demonstrating the bypass control of the liquid hydrogen in the gas supply unit which concerns on Embodiment 2 of this invention. It is a figure which shows typically the structure of the gas supply unit and mixed combustion electric power generating apparatus which concern on the modification of Embodiment 2 of this invention. It is a figure which shows typically the structure of the gas supply unit which concerns on Embodiment 3 of this invention, and a co-firing power generation apparatus. It is a figure which shows typically the structure of the gas supply unit and mixed combustion electric power generating apparatus which concern on Embodiment 4 of this invention.

  Hereinafter, based on the drawings, a gas supply unit according to an embodiment of the present invention and a mixed combustion power generation apparatus including the gas supply unit will be described in detail.

(Embodiment 1)
First, a gas supply unit 1 and a co-fired power generation apparatus 100 according to Embodiment 1 of the present invention will be described with reference to FIG. FIG. 1 schematically shows the configuration of the gas supply unit 1 and the co-fired power generation apparatus 100. FIG. 1 shows only main components of the gas supply unit 1 and the co-fired power generation device 100, and the gas supply unit 1 and the co-fired power generation device 100 may include arbitrary components that do not appear in FIG. .

  The co-fired power generation apparatus 100 is an apparatus that generates thermal power using natural gas G2 and hydrogen gas G1 as fuel. As shown in FIG. 1, the co-fired power generation apparatus 100 mainly includes a gas supply unit 1 and a co-fired power generation unit 40 that generates power using natural gas G2 and hydrogen gas G1 supplied from the gas supply unit 1 as fuel. Yes.

  The gas supply unit 1 is arranged alongside the NG supply unit 20 for supplying the natural gas G2 to the co-firing power generation unit 40, and a hydrogen gas supply unit for supplying the hydrogen gas G1 to the co-firing power generation unit 40. 10 are included. The co-fired power generation unit 40 includes a combustor (not shown) that combusts the natural gas G2 and the hydrogen gas G1 supplied from the gas supply unit 1, and a gas turbine 41 that is rotated by the combustion gas. The co-firing power generation unit 40 generates power by rotating the gas turbine 41 with combustion gas.

  As shown in FIG. 1, the NG supply unit 20 includes an LNG tank 21, an LNG path 23, an LNG pump 22, and an LNG vaporizer 24. The LNG tank 21 stores the liquefied natural gas L2. In the LNG tank 21, a boil-off gas G is generated by evaporating a part of the liquefied natural gas L2 by heat entering from the outside.

  The LNG path 23 is a pipe through which the liquefied natural gas L2 flowing out from the LNG tank 21 flows. As shown in FIG. 1, one end of the LNG path 23 is connected to the LNG tank 21 and the other end is connected to the mixed combustion power generation unit 40. Even in the LNG path 23, a part of the liquefied natural gas L2 is evaporated by heat entering from the outside, and the boil-off gas G can be generated.

  The LNG pump 22 raises the liquefied natural gas L2 flowing out from the LNG tank 21 to a predetermined pressure and sends it out toward the LNG vaporizer 24. As shown in FIG. 1, the LNG pump 22 is disposed upstream of the LNG vaporizer 24 in the LNG path 23 in the flow direction of the liquefied natural gas L2.

  The LNG vaporizer 24 is a heat exchanger that vaporizes the liquefied natural gas L <b> 2 flowing from the LNG path 23, and is disposed on the downstream side of the LNG pump 22 in the LNG path 23. Specifically, the LNG vaporizer 24 includes a first flow path 24A connected to the LNG path 23 and a second flow path 24B through which the heat source medium H2 flows, and the liquefied natural gas flowing through the first flow path 24A. Heat exchange is possible between the gas L2 and the heat source medium H2 flowing through the second flow path 24B.

  By this heat exchange, the liquefied natural gas L2 is vaporized to generate the natural gas G2, and the natural gas G2 is supplied to the mixed combustion power generation unit 40 as fuel. As the heat source medium H2, for example, seawater or air can be used, but it is not particularly limited.

  As shown in FIG. 1, the hydrogen gas supply unit 10 includes an LH 2 tank 11, an LH 2 path 13, an LH 2 pump 12, and an LH 2 vaporizer 14. The LH2 tank 11 stores liquid hydrogen L1 (LH2).

  The LH2 path 13 is a pipe through which the liquid hydrogen L1 flowing out from the LH2 tank 11 flows. As shown in FIG. 1, the LH2 path 13 has one end connected to the LH2 tank 11 and the other end connected to the mixed combustion power generation unit 40.

  The LH2 pump 12 raises the liquid hydrogen L1 flowing out from the LH2 tank 11 to a predetermined pressure and sends it out toward the LH2 vaporizer 14. As shown in FIG. 1, the LH2 pump 12 is disposed upstream of the LH2 vaporizer 14 in the LH2 path 13 in the flow direction of the liquid hydrogen L1.

  The LH2 vaporizer 14 is a heat exchanger that vaporizes the liquid hydrogen L1 flowing from the LH2 path 13, and is disposed downstream of the LH2 pump 12 in the LH2 path 13. Specifically, the LH2 vaporizer 14 includes a first flow path 14A connected to the LH2 path 13 and a second flow path 14B through which the heat source medium H1 flows, and liquid hydrogen flowing through the first flow path 14A. Heat exchange is possible between L1 and the heat source medium H1 flowing through the second flow path 14B.

  By this heat exchange, the liquid hydrogen L1 is vaporized to generate hydrogen gas G1, and the hydrogen gas G1 is supplied to the co-fired power generation unit 40 as fuel. As the heat source medium H1, for example, seawater or air can be used, but it is not particularly limited.

  As shown in FIG. 1, the gas supply unit 1 further includes a BOG path 32, a liquefier 30, and a return path 31.

  The BOG path 32 is a pipe into which the boil-off gas G generated when the liquefied natural gas L2 evaporates in the LNG tank 21 flows. The BOG path 32 has one end connected to the upper part of the LNG tank 21 and the other end connected to the inlet of the liquefier 30.

  As shown in FIG. 1, a branch path 35 is connected in the middle of the BOG path 32, and a BOG compressor 33 is disposed on the branch path 35. The BOG compressor 33 can boost the boil-off gas G flowing from the BOG path 32 into the branch path 35 to a predetermined pressure. The boosted boil-off gas G (natural gas) may be supplied to the mixed combustion power generation unit 40 as fuel.

  Further, as shown in FIG. 1, a BOG path 38 into which the boil-off gas G generated by the evaporation of the liquefied natural gas L2 upstream from the LNG pump 22 in the LNG path 23 may be provided. Thereby, the boil-off gas G generated by the evaporation of the liquefied natural gas L2 before being pressurized by the LNG pump 22 can be guided to the liquefier 30.

  The liquefier 30 is a heat exchanger that cools and liquefies the boil-off gas G. As shown in FIG. 1, the liquefier 30 includes a first flow path 91 connected to the BOG path 32 and the return path 31, and a second flow path 92 connected to the LH2 path 13. More specifically, the downstream end of the BOG path 32 is connected to the inlet of the first flow path 91, and the upstream end of the return path 31 is connected to the outlet of the first flow path 91. According to the liquefier 30, the liquid hydrogen L1 flowing into the second flow path 92 from the LH2 path 13 (liquid hydrogen L1 before flowing into the LH2 vaporizer 14) and the first from the BOG path 32 (or BOG path 38). The boil-off gas G can be cooled and liquefied by heat exchange with the boil-off gas G flowing into the flow path 91.

  The liquid hydrogen L1 is vaporized in the LH2 vaporizer 14 after obtaining a part of the heat of vaporization through heat exchange with the boil-off gas G in the liquefier 30. Since the flow rate of the boil-off gas G flowing into the liquefier 30 varies depending on conditions such as the outside air temperature, it is difficult to reliably vaporize the liquid hydrogen L1 in the liquefier 30. Therefore, in order to reliably vaporize the liquid hydrogen L1, it is necessary to arrange the LH2 vaporizer 14 downstream of the liquefier 30.

  The return path 31 is a pipe for returning the boil-off gas G (liquefied natural gas L2) liquefied by the liquefier 30 to the LNG tank 21. As shown in FIG. 1, the return path 31 has an upstream end connected to the outlet of the first flow path 91 of the liquefier 30 and a downstream end connected to the LNG tank 21.

  As described above, the gas supply unit 1 according to the present embodiment is disposed in the LNG tank 21 that stores the liquefied natural gas L2, the LNG path 23 in which the liquefied natural gas L2 that has flowed out of the LNG tank 21 flows, and the LNG path 23. The LNG vaporizer 24 that vaporizes the liquefied natural gas L2 flowing in from the LNG path 23, the LH2 tank 11 that stores the liquid hydrogen L1, the LH2 path 13 in which the liquid hydrogen L1 flowing out of the LH2 tank 11 flows, and the LH2 path 13 Is generated when the liquefied natural gas L2 evaporates in the LNG tank 21 (or the upstream side of the LNG pump 22 in the LNG path 23) and the LH2 vaporizer 14 that vaporizes the liquid hydrogen L1 flowing in from the LH2 path 13 BOG path 32 (BOG path 38) through which the boil-off gas G flowing in, and BOG path 3 And a liquefier 30 that cools and liquefies the boil-off gas G by heat exchange between the liquid hydrogen L1 flowing from the LH2 path 13 and the boil-off gas G flowing from the BOG path 32. And a return path 31 for returning the boil-off gas G liquefied by the liquefier 30 to the LNG tank 21.

  In this gas supply unit 1, since the liquid hydrogen L1 before vaporization can be used as a cold heat source for liquefying the boil-off gas G, the boil-off gas G can be liquefied with high efficiency. As a result, the amount of liquefied natural gas L2 returned to the LNG tank 21 through the return path 31 increases, and the amount of boil-off gas G compressed by the BOG compressor 33 can be reduced. The pressure increase in the gas state by the BOG compressor 33 requires much power compared to the pressure increase in the liquid state by the LNG pump 22. On the other hand, the energy efficiency in the gas supply to the co-firing power generation unit 40 can be improved by reducing the processing amount by the BOG compressor 33 as described above. In addition, since the NG supply unit 20 and the hydrogen gas supply unit 10 have the same demand for gas supply (mixed combustion power generation unit 40), problems such as an increase in cost for arranging them close to each other can be avoided.

(Embodiment 2)
Next, the gas supply unit 2 and the co-fired power generation apparatus 200 according to Embodiment 2 of the present invention will be described with reference to FIG. The gas supply unit 2 and the co-fired power generation apparatus 200 according to the second embodiment basically have the same configuration as the gas supply unit 1 and the co-fired power generation apparatus 100 according to the first embodiment and have the same effects. The second embodiment is different from the first embodiment in that a bypass path 50 that bypasses the liquefier 30 is connected to the LH2 path 13. Only differences from the first embodiment will be described below.

  As shown in FIG. 2, the gas supply unit 2 further includes a bypass path 50, a bypass valve 51, a detection mechanism 60, and a control unit 70. The BOG path 32 is provided with a flow rate adjusting valve 34.

  The bypass path 50 is a pipe connected to the LH2 path 13 so as to bypass the liquefier 30. As shown in FIG. 2, the upstream end of the bypass path 50 is connected between the LH2 pump 12 and the liquefier 30 in the LH2 path 13. On the other hand, the downstream end of the bypass path 50 is connected between the liquefier 30 and the LH2 vaporizer 14 in the LH2 path 13.

  Thereby, the liquid hydrogen L1 boosted by the LH2 pump 12 can be caused to flow through the bypass path 50 to bypass the liquefier 30. Then, the liquid hydrogen L1 flowing through the bypass path 50 can be merged with the liquid hydrogen L1 flowing out from the liquefier 30, and then flow into the LH2 vaporizer 14.

  The bypass valve 51 controls the inflow of the liquid hydrogen L1 from the LH2 path 13 to the bypass path 50, and is constituted by a flow rate adjusting valve in the present embodiment. By adjusting the opening degree of the bypass valve 51, the flow rate of the liquid hydrogen L1 flowing from the LH2 path 13 into the bypass path 50 is adjusted, and thereby the liquid hydrogen L1 flowing into the liquefier 30 (second flow path 92). The flow rate is also adjusted. The bypass valve is not limited to the flow rate adjustment valve, and may be, for example, an on-off valve.

  The detection mechanism 60 is a sensor for obtaining various detection values for detecting the closed state of the first flow path 91 (flow path through which the boil-off gas G flowing from the BOG path 32 flows). That is, since the liquid hydrogen L1 is a cryogenic liquid, the liquefied natural gas L2 that has been excessively cooled by the liquid hydrogen L1 is frozen in the first flow path 91, thereby closing the first flow path 91. Sometimes. On the other hand, the blockage of the first flow path 91 due to the freezing of the liquefied natural gas L2 can be detected from the detection result of the detection mechanism 60. As shown in FIG. 1, the detection mechanism 60 in the present embodiment includes a differential pressure detection unit 61, an outlet temperature detection unit 62, a liquefier temperature detection unit 63, an inlet side flow rate detection unit 64, and an outlet side flow rate detection. Part 65.

  The differential pressure detection unit 61 is a sensor that detects a differential pressure before and after the first flow path 91. That is, the differential pressure detector 61 can detect the difference between the pressure of the boil-off gas G flowing into the first flow path 91 and the pressure of the liquefied natural gas L2 flowing out of the first flow path 91. When it is larger, the blockage of the first flow path 91 can be detected.

  The outlet temperature detection unit 62 is a sensor that detects the temperature of the liquefied natural gas L2 that has flowed out of the first flow path 91. The outlet temperature detection unit 62 is provided in the vicinity of the outlet of the first flow path 91, but the position is not particularly limited. The liquefier temperature detection unit 63 is a sensor that detects the temperature of the liquefier 30. Even when the temperature detected by these sensors is lower than a predetermined threshold temperature, the blockage of the first flow path 91 can be detected.

  The inlet-side flow rate detection unit 64 is a sensor that detects the flow rate of the boil-off gas G on the inlet side of the first flow path 91. The outlet side flow rate detection unit 65 is a sensor that detects the flow rate of the liquefied natural gas L2 on the outlet side of the first flow path 91. Even when the flow rate detection values by these sensors are lower than a predetermined threshold value, the blockage of the first flow path 91 can be detected.

  The detection mechanism 60 includes at least one of a differential pressure detection unit 61, an outlet temperature detection unit 62, a liquefier temperature detection unit 63, an inlet side flow rate detection unit 64, and an outlet side flow rate detection unit 65. Well, it is not limited to those including all of these detection units.

  The control unit 70 controls the bypass valve 51 based on the detection result by the detection mechanism 60, and includes a reception unit 71, a storage unit 72, a comparison determination unit 73, and a bypass valve control unit 74. These are functions of a CPU (Central Processing Unit) in the computer constituting the control unit 70.

  The accepting unit 71 accepts information on a detection result by the detection mechanism 60. That is, detection results by the differential pressure detection unit 61, the outlet temperature detection unit 62, the liquefier temperature detection unit 63, the inlet side flow rate detection unit 64, and the outlet side flow rate detection unit 65 are input to the reception unit 71.

The storage unit 72 stores various threshold values used for controlling the bypass valve 51. For example, the storage unit 72, stores the threshold [Delta] P H of the differential pressure across the first flow path _91, the low-temperature side threshold T _L and the high temperature side threshold T _H of the outlet temperature of the liquefier 30 for the outlet temperature of the liquefier 30, respectively doing. The storage unit 72 may further store a threshold value for the temperature of the liquefier 30 and a threshold value for the flow rate on the inlet side and the outlet side of the liquefier 30.

  The comparison determination unit 73 compares the detection result input to the reception unit 71 with the threshold value stored in the storage unit 72. The bypass valve control unit 74 controls the opening degree of the bypass valve 51 based on the comparison result by the comparison determination unit 73.

  Here, an example of control of the bypass valve 51 by the control unit 70 will be described according to the flowchart shown in FIG.

First, compared with the threshold value [Delta] P _H of the actual differential pressure [Delta] P and the differential pressure detected by the differential pressure detection unit 61 determines whether or not [Delta] P is less than [Delta] P _H (step S1). Here, if [Delta] P is not less than [Delta] P _H ( "NO" in step S1), and increases the opening degree of the bypass valve 51 (step S2). Thereby, the flow rate of the liquid hydrogen L1 flowing into the liquefier 30 from the LH2 path 13 is reduced, and freezing in the first flow path 91 is alleviated. On the other hand, if [Delta] P is less than [Delta] P _H ( "YES" in step S1), the without adjustment of the opening degree of the bypass valve 51, the flow proceeds to step S3.

In step S3, the actual temperature T _LNG of the liquefied natural gas L2 detected by the outlet temperature detection unit 62 is compared with the low temperature side threshold value _TL, and it is determined whether or not T _LNG exceeds _TL . Here, when _TLNG is equal to or less than _TL (“NO” in step S3), the opening degree of the bypass valve 51 is increased (step S4). As a result, the flow rate of the liquid hydrogen L1 flowing into the liquefier 30 is reduced, and the liquefied natural gas L2 can be prevented from approaching the freezing temperature, so that freezing in the first flow path 91 is alleviated. On the other hand, when _TLNG exceeds _TL (“YES” in step S3), the opening degree of the bypass valve 51 is not adjusted, and the process proceeds to step S5.

In step S5, compared with the temperature _{T LNG} and the high temperature side threshold _{T H,} it determines whether _{T LNG} is less than _{T H. Here,} ( "NO" in step S5). If _{T LNG} is above _{T H,} reducing the opening degree of the bypass valve 51 (step S6). As a result, the amount of liquid hydrogen L1 flowing into the liquefier 30 is increased, and the liquefied natural gas L2 can be cooled to an appropriate temperature. On the other _hand, if _{T LNG} is less than _{T H} ( "YES" in step S5), and without adjustment of the opening degree of the bypass valve 51, the flow returns to step S1.

  Thus, by adjusting the opening degree of the bypass valve 51 based on the detection result by the detection mechanism 60, the flow rate of the liquid hydrogen L1 flowing into the liquefier 30 is prevented so as to prevent freezing in the first flow path 91. Can be adjusted. In the present embodiment, only the control using the detection results of the differential pressure detection unit 61 and the outlet temperature detection unit 62 has been described, but the present invention is not limited to this. Control using the detection results of the liquefier temperature detection unit 63, the inlet side flow rate detection unit 64, and the outlet side flow rate detection unit 65 may be similarly performed.

  Further, as shown in the modification of FIG. 4 (gas supply unit 2A, co-fired power generation apparatus 200A), the bypass valve 52 may be provided not only in the bypass path 50 but also in the LH2 path 13. As shown in FIG. 4, the bypass valve 52 is disposed upstream of the liquefier 30 in the LH2 path 13 and downstream of the connection portion at the upstream end of the bypass path 50.

  The bypass valve 52 is a flow rate adjustment valve (or on-off valve), similar to the bypass valve 51, and is controlled by the control unit 70. That is, increasing the opening degree of the bypass valve 52 increases the flow rate of the liquid hydrogen L1 flowing into the liquefier 30, and decreasing the opening degree of the bypass valve 52 decreases the flow rate of the liquid hydrogen L1 flowing into the liquefier 30. Can be reduced. Thus, by using two valves together, it becomes easier to adjust the flow rate of the liquid hydrogen L1 flowing into the liquefier 30. Alternatively, the bypass valve 51 may be omitted, and the flow rate of the liquid hydrogen L1 flowing into the liquefier 30 may be adjusted using only the bypass valve 52.

  Moreover, although this embodiment demonstrated the case where the bypass valve 51 was automatically controlled by the control part 70, it is not limited to this. That is, the detection mechanism 60 and the control unit 70 may be omitted, and the bypass valve 51 may be manually controlled.

(Embodiment 3)
Next, the gas supply unit 3 and the co-fired power generation apparatus 300 according to Embodiment 3 of the present invention will be described with reference to FIG. The gas supply unit 3 and the co-fired power generation apparatus 300 according to the third embodiment basically have the same configuration as the gas supply unit 2 and the co-fired power generation apparatus 200 according to the second embodiment and have the same effects. The second embodiment is different from the second embodiment in that a plurality of liquefiers 30 are provided. Only differences from the second embodiment will be described below.

  As shown in FIG. 5, the gas supply unit 3 includes a plurality of liquefiers 30 (first liquefier 30A and second liquefier 30B). The first liquefier 30A and the second liquefier 30B have the same configuration, and have a first flow path 91 through which the boil-off gas G flows and a second flow path 92 through which liquid hydrogen L1 flows.

  The LH2 path 13 is branched into a plurality of paths (two in this embodiment). Specifically, the LH2 path 13 extends from the outlet of the LH2 tank 11 to the inlet of the co-fired power generation unit 40 and is connected to the first LH2 path 13A connected to the first liquefier 30A (second flow path 92). And a second LH2 path 13B having both ends connected to the first LH2 path 13A so as to bypass the first liquefier 30A while being connected to the vessel 30B (second flow path 92).

  Also, the BOG path 32 is branched into a plurality of paths (two in this embodiment). Specifically, the BOG path 32 extends from the LNG tank 21 to the first liquefier 30A and has a first BOG path 32A having a downstream end connected to the inlet of the first flow path 91 of the first liquefier 30A. A second BOG path 32B extending from the middle of the 1BOG path 32A to the second liquefier 30B and having a downstream end connected to the inlet of the first flow path 91 of the second liquefier 30B. The first liquefier 30A and the second liquefier 30B are arranged in parallel in two branched paths of the LH2 path 13 and the BOG path 32.

  The return path 31 includes a first return path 31A connected to the outlet of the first flow path 91 of the first liquefier 30A and a second return connected to the outlet of the first flow path 91 of the second liquefier 30B. And a path 31B. As shown in FIG. 5, the first return path 31 </ b> A has an upstream end connected to the outlet of the first flow path 91 of the first liquefier 30 </ b> A and a downstream end connected to the LNG tank 21. On the other hand, the second return path 31B has an upstream end connected to the outlet of the first flow path 91 of the second liquefier 30B and a downstream end connected in the middle of the first return path 31A.

  The gas supply unit 3 includes an LH2 switching valve 55 that switches inflow of liquid hydrogen L1 into each of the first liquefier 30A and the second liquefier 30B, and boil-off to each of the first liquefier 30A and the second liquefier 30B. A BOG switching valve 83 that switches inflow of the gas G.

  As shown in FIG. 5, the LH2 switching valve 55 includes a first LH2 switching valve 53 disposed on the upstream side of the first liquefier 30A in the first LH2 path 13A, and an upstream side of the second liquefier 30B in the second LH2 path 13B. 2nd LH2 change-over valve 54 arranged in. The first LH2 switching valve 53 and the second LH2 switching valve 54 are, for example, on-off valves, and are controlled by the control unit 70.

  The BOG switching valve 83 includes a first BOG switching valve 81 disposed on the downstream side of the connection portion of the second BOG path 32B in the first BOG path 32A, and a second BOG switching valve 82 disposed on the second BOG path 32B. . The first BOG switching valve 81 and the second BOG switching valve 82 are, for example, on-off valves, and are controlled by the control unit 70.

  In the gas supply unit 3, the use of the first liquefier 30A and the second liquefier 30B can be switched as follows. First, when the first LH2 switching valve 53 and the first BOG switching valve 81 are open and the second LH2 switching valve 54 and the second BOG switching valve 82 are closed, the liquid hydrogen L1 and the boil-off gas G do not flow into the second liquefier 30B. , Flows only into the first liquefier 30A.

  Here, when LNG freezes in the flow path of the first liquefier 30A, it is necessary to switch the use from the first liquefier 30A to the second liquefier 30B. In this case, the first LH2 switching valve 53 and the first BOG switching valve 81 are closed, and the second LH2 switching valve 54 and the second BOG switching valve 82 are opened. Thereby, it can switch to the state into which liquid hydrogen L1 and boil-off gas G do not flow into the 1st liquefier 30A, but flow into only the 2nd liquefier 30B.

  Thus, the timing for switching the use of the liquefier 30 is based on the detection results of the differential pressure detection unit 61, the outlet temperature detection unit 62, the liquefier temperature detection unit 63, the inlet side flow rate detection unit 64, or the outlet side flow rate detection unit 65. You may decide based on. That is, when the detection result by these detection units exceeds the threshold value or falls below the threshold value, it is determined that the flow path of the liquefier 30 being used is blocked by freezing, and switching to use of another liquefier 30 is possible. Good. In addition, when the flow path is closed in both the first liquefier 30A and the second liquefier 30B, the liquid hydrogen L1 may flow through the bypass path 50.

  Moreover, use of the liquefier 30 is not limited to the case where it switches automatically, You may switch manually. Further, three or more liquefiers 30 may be provided, and branch paths and switching valves may be provided according to the number of liquefiers 30.

(Embodiment 4)
Next, the gas supply unit 4 and the co-fired power generation apparatus 400 according to Embodiment 4 of the present invention will be described with reference to FIG. The gas supply unit 4 and the co-fired power generation apparatus 400 according to the fourth embodiment basically have the same configuration as the gas supply unit 3 and the co-fired power generation apparatus 300 according to the third embodiment and have the same effects. The third embodiment is different from the third embodiment in that it further includes a melting mechanism 110 that melts LNG frozen in the first flow path 91 of the liquefier 30. Only differences from the third embodiment will be described below.

  The melting mechanism 110 in the present embodiment is configured to return a part of the hydrogen gas G1 vaporized by the LH2 vaporizer 14 to the upstream side of the liquefier 30 in the LH2 path 13. Specifically, as shown in FIG. 6, the melting mechanism 110 includes a hydrogen return path 111, switching valves 113 to 115, and a blower 112.

  The hydrogen return path 111 has an upstream end connected to the downstream side of the LH2 vaporizer 14 in the first LH2 path 13A, and has a plurality of downstream ends (two in this embodiment). As shown in FIG. 6, one of the branch paths is connected between the first LH2 switching valve 53 and the first liquefier 30A in the first LH2 path 13A, and the other of the branch paths is the second in the second LH2 path 13B. It is connected between the 2LH2 switching valve 54 and the second liquefier 30B. In addition, switching valves 113 and 114 are arranged on the respective branch paths.

  The blower 112 pumps the hydrogen gas G <b> 1 toward the upstream side of the liquefier 30, and is arranged in the hydrogen return path 111. Further, on the upstream side of the blower 112, a switching valve 115 that switches inflow and shut-off of the hydrogen gas G1 to the blower 112 is disposed.

  For example, when LNG is frozen in the first flow path 91 of the first liquefier 30A, the switching valves 113 and 115 are opened and the blower 112 is operated. Accordingly, the hydrogen gas G1 is returned to the upstream side of the first liquefier 30A through the hydrogen return path 111 and flows into the second flow path 92 of the first liquefier 30A.

  As a result, the heat transfer surface of the second flow path 92 is warmed by the heat of the hydrogen gas G1, and the heat transfer surface of the first flow path 91 is also warmed by heat transfer from the second flow path 92 to the first flow path 91. It is done. As a result, the LNG frozen in the first flow path 91 can be thawed. On the other hand, when LNG is frozen in the first flow path 91 of the second liquefier 30B, the melting process can be similarly performed by opening the switching valve 114 instead of the switching valve 113.

  The melting mechanism is not limited to the one that returns the hydrogen gas G1 to the upstream side of the liquefier 30, and the natural gas G2 may be returned to the upstream side of the liquefier 30. However, it is preferable to return the hydrogen gas G1 in order to avoid trouble when the natural gas G2 is caused to flow through the first flow path 91 closed by freezing. The melting mechanism may be a blower that blows air to the liquefier 30 and melts it by the heat of the air, may be a heater attached to the liquefier 30, or is a pipe that flows seawater. It may be melted by the heat of the seawater.

  In the present embodiment, the case where the melting mechanism 110 is provided in the gas supply unit including the plurality of liquefiers 30 has been described. However, the melting mechanism 110 may be provided in the gas supply unit including the single liquefier 30. Good.

(Other embodiments)
Finally, other embodiments of the present invention will be described.

  In the first to fourth embodiments, only the case where gas is supplied to the mixed combustion power generation unit 40 has been described. However, the use of the gas supply unit is not limited to this. That is, the natural gas G2 and the hydrogen gas G1 may be supplied from the gas supply unit to any demand destination other than the mixed combustion power generation unit 40.

  In the first to fourth embodiments, the case where the LH2 pump 12 is disposed on the upstream side of the liquefier 30 has been described. However, an LH2 pump may be further disposed between the liquefier 30 and the LH2 vaporizer 14.

  It should be understood that the embodiments disclosed herein are illustrative and non-restrictive in every respect. The scope of the present invention is defined by the terms of the claims, rather than the description above, and is intended to include any modifications within the scope and meaning equivalent to the terms of the claims.

1, 2, 2A, 3, 4 Gas supply unit 11 LH2 tank 13 LH2 path 13A 1st LH2 path 13B 2nd LH2 path 14 LH2 vaporizer 21 LNG tank 23 LNG path 24 LNG vaporizer 30 liquefier 30A 1st liquefier 30B 1st 2-liquefier 31 Return path 32, 38 BOG path 32A 1st BOG path 32B 2nd BOG path 40 Co-firing power generation unit 50 Bypass path 51, 52 Bypass valve 55 LH2 switching valve 60 Detection mechanism 61 Differential pressure detection section 62 Outlet temperature detection section 63 Liquefaction Temperature detecting unit 64 Inlet side flow rate detecting unit 65 Outlet side flow rate detecting unit 70 Control unit 83 BOG switching valve 100, 200, 200A, 300, 400 Mixed combustion power generation device 110 Melting mechanism G Boil-off gas L1 Liquid hydrogen L2 Liquefied natural gas

Claims (7)

An LNG tank for storing liquefied natural gas;
An LNG path through which liquefied natural gas flowing out of the LNG tank flows;
An LNG vaporizer disposed in the LNG path and vaporizing liquefied natural gas flowing from the LNG path;
An LH2 tank for storing liquid hydrogen;
An LH2 path through which liquid hydrogen flowing out of the LH2 tank flows;
An LH2 vaporizer disposed in the LH2 path and vaporizing liquid hydrogen flowing from the LH2 path;
A BOG path through which boil-off gas generated by evaporation of liquefied natural gas in at least one of the LNG tank and the LNG path flows;
A liquefier that is connected to the BOG path and the LH2 path, and cools and liquefies the boil-off gas by heat exchange between the liquid hydrogen flowing from the LH2 path and the boil-off gas flowing from the BOG path;
A gas supply unit comprising: a return path connected to the liquefier and returning boil-off gas liquefied by the liquefier to the LNG tank. A bypass path connected to the LH2 path to bypass the liquefier;
The gas supply unit according to claim 1, further comprising a bypass valve that controls inflow of liquid hydrogen from the LH2 path to the bypass path. The liquefier has a flow path through which boil-off gas flowing from the BOG path flows,
A differential pressure detector that detects a differential pressure before and after the flow path, an outlet temperature detector that detects the temperature of the liquefied natural gas that has flowed out of the flow path, a liquefier temperature detector that detects the temperature of the liquefier, A detection mechanism including at least one of an inlet-side flow rate detection unit that detects the flow rate of boil-off gas on the inlet side of the flow channel and an outlet-side flow rate detection unit that detects the flow rate of liquefied natural gas on the outlet side of the flow channel;
The gas supply unit according to claim 2, further comprising a control unit that controls the bypass valve based on a detection result by the detection mechanism. The LH2 route and the BOG route are branched into a plurality of routes,
A plurality of the liquefiers are arranged in parallel in the plurality of paths;
An LH2 switching valve that switches inflow of liquid hydrogen to each of the plurality of liquefiers, and a BOG switching valve that switches inflow of boil-off gas to each of the plurality of liquefiers are further provided. Item 4. The gas supply unit according to any one of Items 1 to 3.   5. The melting mechanism according to claim 1, further comprising a melting mechanism that melts liquefied natural gas frozen in a flow path through which boil-off gas flowing from the BOG path flows in the liquefier. Gas supply unit.   The gas supply unit according to claim 5, wherein the melting mechanism is configured to return a part of the hydrogen gas vaporized by the LH2 vaporizer to the upstream side of the liquefier in the LH2 path. The gas supply unit according to any one of claims 1 to 6,
A co-fired power generation apparatus, comprising: a co-fired power generation unit that generates power using natural gas and hydrogen gas supplied from the gas supply unit as fuel.

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