A BOG power generation system for LNG receiving station

Abstract

The present invention relates to the field of LNG receiving stations, and discloses a BOG power generation system of an LNG receiving station, including an LNG storage tank, on which a BOG outlet is provided; a gas mixing component and a gas turbine, wherein the BOG outlet, the gas mixing component and the fuel inlet of the gas turbine are connected in sequence; and the gas mixing component is used to evenly mix the BOG gas entering the gas mixing component from the BOG outlet with the gas fuel other than the BOG gas entering the gas mixing component. The present invention can mix the BOG gas and the gas fuel other than the BOG gas in the gas mixing component by adding a gas mixing component, thereby ensuring the uniformity of the mixing of the BOG gas and the gas fuel other than the BOG gas, and reducing the fluctuation range of the calorific value of the mixed gas source formed by the mixing of the BOG gas and the gas fuel other than the BOG gas transported to the gas turbine through the gas mixing component, thereby ensuring the stability of the gas turbine during power generation, and solving the problem of the gas turbine being shut down due to the large fluctuation range of the calorific value of the mixed gas source formed by the mixing of the BOG gas and the gas fuel other than the BOG gas.

Description

Technical Field

[0001] The present invention relates to the field of LNG receiving stations, and in particular to a BOG power generation system for LNG receiving stations. Background Art

[0002] LNG (Liquefied Natural Gas) is the abbreviation of liquefied natural gas. LNG will produce steam BOG during the storage process. The usual treatment methods are re-condensation, compression and external transmission, or liquefaction and return to the LNG storage tank.

[0003] BOG is formed when LNG flashes during storage. The usual way to deal with BOG is to condense it through a recondenser, or to compress the BOG and then output it to a BOG storage tank, or to liquefy the BOG into LNG using a heat exchanger and return the liquefied LNG to the LNG storage tank.

[0004] In addition to the above methods, there is another method that uses BOG as fuel for gas turbines to generate electricity, and when BOG is insufficient, external natural gas will be used as a backup gas source. However, when two gas sources are used at the same time, the stability of gas turbine power generation will be affected due to the different components of the two gas sources. Summary of the invention

[0005] The object of the present invention is to provide a BOG power generation system for an LNG receiving station, which can solve the problem that when BOG and natural gas are used as gas sources at the same time, the different components of the two gas sources will affect the stability of gas turbine power generation.

[0006] To achieve this object, the present invention adopts the following technical solutions:

[0007] A BOG power generation system for an LNG receiving station, the BOG power generation system for an LNG receiving station comprising:

[0008] An LNG storage tank, wherein the LNG storage tank is provided with a BOG outlet;

[0009] A gas mixing component and a gas turbine, wherein the BOG outlet, the gas mixing component and a fuel inlet of the gas turbine are sequentially connected, and the gas mixing component is used to mix the BOG gas entering the gas mixing component from the BOG outlet with a gas fuel other than the BOG gas entering the gas mixing component.

[0010] As a preferred technical solution of the BOG power generation system of the above-mentioned LNG receiving station, the gas mixing component includes:

[0011] A fuel gas buffer tank, one end of which is connected to the fuel inlet of the gas turbine;

[0012] A gas dispersion pipe, one end of which is connected to the BOG outlet through a BOG gas power generation pipeline and is selectively connected or disconnected with the natural gas outlet of the first gasifier, and the other end of which extends into the gas buffer tank; a plurality of gas dispersion holes are provided on the gas dispersion pipe.

[0013] As a preferred technical solution of the BOG power generation system of the LNG receiving station, the end of the gas dispersion pipe extending into the gas buffer tank is sealed.

[0014] As a preferred technical solution for the above-mentioned LNG receiving station BOG power generation system, an air flow baffle located downstream of the gas dispersion pipe is provided in the gas buffer tank, and a center hole connecting the air inlet and the air outlet of the gas buffer tank is provided on the air flow baffle.

[0015] As a preferred technical solution of the BOG power generation system of the LNG receiving station, the central axis of the central hole coincides with the central axis of the gas dispersion pipe.

[0016] As a preferred technical solution of the BOG power generation system of the above-mentioned LNG receiving station, it also includes:

[0017] An LNG tank pump, used to extract LNG liquid from the LNG storage tank;

[0018] The first vaporizer, the LNG outlet of the pump in the LNG tank is connected to the LNG inlet of the first vaporizer, and the natural gas outlet of the first vaporizer is selectively connected or disconnected with the fuel inlet of the gas mixing component.

[0019] As a preferred technical solution of the above-mentioned BOG power generation system of the LNG receiving station, it also includes a waste heat recovery heat exchanger, and the exhaust gas discharge port of the gas turbine is connected to the heat source inlet of the waste heat recovery heat exchanger.

[0020] As a preferred technical solution of the BOG power generation system of the above-mentioned LNG receiving station, the medium channel of the waste heat recovery heat exchanger and the heat source channel of the first gasifier can form a first circulation loop.

[0021] As a preferred technical solution of the above-mentioned BOG power generation system of the LNG receiving station, it also includes a heat exchange device, and the medium channel of the waste heat recovery heat exchanger and the heat source channel of the heat exchange device can form a circulation loop.

[0022] As a preferred technical solution of the BOG power generation system of the LNG receiving station, it also includes a BOG compressor, and the inlet and outlet of the BOG compressor are respectively connected to the BOG outlet and the fuel inlet of the gas mixing component.

[0023] Beneficial effects of the present invention: The BOG power generation system of the LNG receiving station provided by the present invention can mix BOG gas and gas fuel other than BOG gas in the gas mixing component by adding a gas mixing component, thereby ensuring the uniformity of the mixing of BOG gas and gas fuel other than BOG gas, and reducing the fluctuation amplitude of the calorific value of the mixed gas source formed by the mixture of BOG gas and gas fuel other than BOG gas transported to the gas turbine through the gas mixing component, thereby ensuring the stability of the gas turbine during power generation, and solving the problem of gas turbine shutdown caused by large fluctuation amplitude of the calorific value of the mixed gas source formed by the mixture of BOG gas and gas fuel other than BOG gas. BRIEF DESCRIPTION OF THE DRAWINGS

[0024] In order to more clearly illustrate the technical solutions in the embodiments of the present invention, the following briefly introduces the drawings required for use in the description of the embodiments of the present invention. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on the contents of the embodiments of the present invention and these drawings without paying any creative work.

[0025] Figure 1 This is a schematic diagram of a BOG power generation system for an LNG receiving station provided by an embodiment of the present invention;

[0026] Figure 2 It is a schematic diagram of the structure of a gas dispersion pipe provided in an embodiment of the present invention.

[0027] In the figure:

[0028] 1. LNG storage tank; 2. BOG compressor; 3. Gas turbine; 4. Gas mixing assembly; 41. Gas buffer tank; 42. Gas dispersion pipe; 421. Gas dispersion hole; 43. Air flow baffle; 44. Center hole; 5. LNG tank internal pump; 6. LNG high-pressure pump; 7. First vaporizer; 8. Waste heat recovery heat exchanger; 9. Second vaporizer; 10. Heating device; 11. Downstream pipeline; 12. Shut-off valve. DETAILED DESCRIPTION

[0029] In order to make the technical problems solved by the present invention, the technical solutions adopted and the technical effects achieved clearer, the technical solutions of the present invention are further described below in conjunction with the accompanying drawings and through specific implementation methods. It is understood that the specific embodiments described herein are only used to explain the present invention, rather than to limit the present invention. It should also be noted that, for the convenience of description, only the parts related to the present invention are shown in the accompanying drawings, not all.

[0030] like Figure 1As shown, this embodiment provides a BOG power generation system for an LNG receiving station, including an LNG storage tank 1, a BOG outlet is provided on the LNG storage tank 1, and the BOG outlet is provided with a BOG compressor 2 and a gas turbine 3 connected in sequence. Preferably, the BOG outlet is provided at the top of the LNG storage tank 1, and the BOG gas formed by flashing of the LNG in the storage process gradually rises to the top of the LNG storage tank 1, and the BOG gas at the top of the LNG storage tank 1 enters the BOG compressor 2 through the BOG outlet, and is sent to the gas turbine 3 for combustion and power generation after being pressurized by the BOG compressor 2. The outlet of the above-mentioned BOG compressor 2 is also connected to a downstream pipeline 11 to send part of the BOG gas to the downstream processing section of the LNG receiving station. It can be understood that if the pressure of the BOG gas flowing out of the BOG outlet is large enough, the present embodiment can also directly connect the BOG outlet to the fuel inlet of the gas turbine 3.

[0031] However, since the amount of BOG gas generated by flash evaporation of LNG liquid in the storage tank often fluctuates, in order to achieve stable power generation of the gas turbine 3, natural gas is usually used as a backup gas source. Of course, other gas fuels can also be used as backup gas sources, which are not specifically limited here. Specifically, an LNG tank pump 5 is provided in the LNG storage tank 1 to extract the LNG liquid in the LNG storage tank 1. Preferably, the LNG tank pump 5 is arranged at the bottom of the LNG storage tank 1. The outlet of the LNG tank pump 5 is provided with an LNG high-pressure pump 6 and a first vaporizer 7 connected in sequence, and the natural gas outlet of the first vaporizer 7 is selectively connected or disconnected with the fuel inlet of the gas turbine 3. When the natural gas outlet of the first vaporizer 7 is connected with the fuel inlet of the gas turbine 3, the first vaporizer 7 can vaporize the LNG gas pressurized by the LNG high-pressure pump 6 to form natural gas, and then transport it to the gas turbine 3, so that the gas turbine 3 can use BOG gas and natural gas to generate electricity at the same time. Preferably, the first vaporizer 7 is an ORV vaporizer or an IFV vaporizer.

[0032] In this embodiment, the natural gas outlet of the first gasifier 7 is connected to a natural gas output pipe and a backup gas source pipe at the same time. A shut-off valve 12 is provided on the backup gas source pipe. When the shut-off valve 12 is opened, the natural gas outlet of the first gasifier 7 and the fuel inlet of the gas turbine 3 can be connected through the backup gas source pipe. When the shut-off valve 12 is closed, the natural gas outlet of the first gasifier 7 and the fuel inlet of the gas turbine 3 are disconnected.

[0033] However, in the process of switching between using BOG gas and natural gas as gas sources at the same time and using BOG gas alone as gas source through the shut-off valve 12, and in the process of mixing BOG gas and natural gas, the gas turbine 3 may be easily shut down due to the large difference in the components of BOG gas and natural gas, which seriously affects the stability of power generation of the gas turbine 3.

[0034] To this end, in this embodiment, a gas mixing component 4 is provided between the BOG compressor 2 and the gas turbine 3, for mixing the natural gas gasified by the first gasifier 7 and the BOG gas delivered by the BOG compressor 2, so that the BOG gas and the natural gas are mixed evenly, which greatly reduces the fluctuation range of the calorific value of the gas source output by the gas mixing component 4, thereby effectively ensuring the stability of the gas turbine 3 during power generation.

[0035] Specifically, Figure 1 and Figure 2 As shown, the gas mixing component 4 includes a gas buffer tank 41 and a gas dispersion pipe 42. One end of the gas buffer tank 41 is connected to the fuel inlet of the gas turbine 3. One end of the gas dispersion pipe 42 is connected to the outlet of the BOG compressor 2 through the BOG gas power generation pipeline, and is selectively connected or disconnected with the natural gas outlet of the first gasifier 7. The other end of the gas dispersion pipe 42 extends into the gas buffer tank 41. The gas dispersion pipe 42 is provided with a plurality of gas dispersion holes 421. The arrangement of the gas mixing component 4 can fully mix the natural gas and BOG, ensure the mixing uniformity of the BOG gas and the natural gas, reduce the fluctuation range of the calorific value of the mixed gas source formed by the BOG gas and the natural gas transported to the gas turbine 3 through the gas mixing component 4, thereby ensuring the stability of the gas turbine 3 during power generation, and solving the problem that the gas turbine 3 is shut down due to the large fluctuation range of the calorific value of the mixed gas source formed by the mixture of BOG gas and natural gas, and the large fluctuation range of the calorific value in the switching process of using BOG gas and natural gas as the gas source at the same time and using BOG gas alone as the gas source. Preferably, the plurality of gas dispersion holes 421 are distributed along the circumferential direction and the axial direction of the gas dispersion pipe 42 , so that the BOG gas and the natural gas entering the gas dispersion pipe 42 can be more fully mixed, and the mixing efficiency is improved.

[0036] Furthermore, the end of the gas dispersion pipe 42 extending into the gas buffer tank 41 is sealed. The above arrangement can prevent the BOG gas and natural gas in the gas buffer tank 41 from being discharged from the gas buffer tank 41 directly through the end of the gas dispersion pipe 42 without being evenly mixed.

[0037] Furthermore, the gas buffer tank 41 is provided with an airflow baffle 43 located downstream of the gas dispersion pipe 42, and a center hole 44 is provided on the airflow baffle 43. Preferably, the center axis of the center hole 44 coincides with the center axis of the gas dispersion pipe 42. The provision of the airflow baffle 43 can enhance the turbulent flow characteristics of the airflow in the gas buffer tank 41, so that the natural gas and BOG are mixed more evenly.

[0038] Further, the airflow baffle 43 includes a horizontal plate and a vertical plate arranged on one side of the horizontal plate, and the vertical plate and the gas dispersion pipe 42 are located on the same side of the horizontal plate, that is, one end of the vertical plate is connected to the horizontal plate, and the other end extends to the side where the gas dispersion pipe 42 is located. Preferably, the horizontal plate is arranged around the vertical plate to form the above-mentioned central hole 44. The above-mentioned arrangement can further enhance the turbulent flow characteristics of the airflow in the gas buffer tank 41, so that the natural gas and BOG are mixed more evenly.

[0039] Furthermore, in the process of power generation by the gas turbine 3, a large amount of high-temperature exhaust gas is generated. In order to avoid heat waste in the high-temperature exhaust gas generated by the gas turbine 3, a waste heat recovery heat exchanger 8 is added in this embodiment, and the exhaust gas discharge port of the gas turbine 3 is connected to the heat source inlet of the waste heat recovery heat exchanger 8. After the high-temperature exhaust gas discharged through the exhaust gas discharge port of the gas turbine 3 enters the heat source inlet of the waste heat recovery heat exchanger 8, the medium in the medium channel of the waste heat recovery heat exchanger 8 is heated by the high-temperature exhaust gas in the heat source channel of the waste heat recovery heat exchanger 8.

[0040] Since the first vaporizer 7 needs heat for vaporizing the LNG liquid during the process of vaporizing the BOG gas, the first vaporizer 7 needs heat for vaporizing the LNG liquid. The medium channel of the waste heat recovery heat exchanger 8 and the heat source channel of the first vaporizer 7 can form a first circulation loop. The medium in the medium channel of the waste heat recovery heat exchanger 8 is heated and then passed into the heat source channel of the first vaporizer 7, providing heat energy for the first vaporizer 7 to vaporize the LNG liquid.

[0041] The BOG power generation system of the LNG receiving station provided in this embodiment also includes a heat exchange device. The medium channel of the waste heat recovery heat exchanger 8 and the heat source channel of the heat exchange device can form a circulation loop, which is used to provide the heat required for heat exchange for the heat exchange device, and utilize the heat energy recovered from the tail gas discharged by the gas turbine 3 through the waste heat recovery heat exchanger 8. Specifically, the heat exchange device includes a second vaporizer 9 and a heating device 10; the medium channel of the waste heat recovery heat exchanger 8 and the heat source channel of the second vaporizer 9 can form a second circulation loop; the medium channel of the waste heat recovery heat exchanger 8 and the heat source channel of the heating device 10 can form a third circulation loop. The medium heated in the medium channel of the waste heat recovery heat exchanger 8 is used to provide the heat required for the second vaporizer 9 to gasify the LNG liquid, and the medium heated in the medium channel of the waste heat recovery heat exchanger 8 can also be used as the heat source of the heating device 10. Preferably, the second vaporizer 9 is an SCV vaporizer. The above-mentioned heat exchange device is not limited to the second vaporizer 9 and the heating device 10, and may also be other adopted structures, which are not listed here one by one.

[0042] This embodiment simultaneously adopts the above three methods to realize the recovery and utilization of the heat in the high-temperature exhaust gas generated by the gas turbine 3, and achieves the purpose of energy saving and consumption reduction.

[0043] The BOG power generation system of the LNG receiving station provided in this embodiment has two gas sources. The first is to use BOG as a gas source for power generation, and the second is to use a mixed gas source of BOG and natural gas for power generation. The following describes the process of using the two gas sources for power generation by examples.

[0044] The first method is to use BOG as the gas source alone, and the shut-off valve 12 is in the closed state. The BOG in the LNG storage tank 1 is transported to the BOG compressor 2 at a flow rate of 8t / h. The BOG compressor 2 pressurizes the LNG liquid to 0.7MPag, and then transports it to the gas turbine 3 through the gas mixing component 4. At this time, the power generated by the gas turbine 3 is about 18000KW. At the same time, the high-temperature exhaust gas generated by the gas turbine 3 is recycled through the waste heat recovery heat exchanger 8, which can generate 4000m 3 / h of hot water, and the exhaust gas after heat exchange with the waste heat recovery heat exchanger 8 is discharged through the exhaust gas emission pipeline. At this time, this part of the hot water can be used as the vaporization heat source of the first vaporizer 7 and the second vaporizer 9, and as the heat source of the heating device 10 to heat the LNG receiving station.

[0045] The second method uses a mixed gas source of BOG gas and natural gas, and the shut-off valve 12 is in an open state. The BOG gas in the LNG storage tank 1 is transported to the BOG compressor 2 at a flow rate of 2t / h. The BOG compressor 2 pressurizes the LNG liquid to 0.5MPag and transports it to the gas mixing component 4; at the same time, the LNG liquid in the LNG storage tank 1 is transported to the LNG high-pressure pump 6 by the LNG tank pump 5, and after being pressurized by the LNG high-pressure pump 6, it is transported to the first vaporizer 7 to gasify into natural gas. The natural gas is transported to the gas mixing component 4 at a flow rate of 7t / h. After the BOG gas and natural gas are fully mixed in the gas mixing component 4, they enter the gas turbine 3 for combustion and power generation; the power generated by the gas turbine 3 is about 20000KW, and the high-temperature exhaust gas generated by the gas turbine 3 is recycled through the waste heat recovery heat exchanger 8, which can generate 4500m 3 / h of hot water, and the exhaust gas after heat exchange with the waste heat recovery heat exchanger 8 is discharged through the exhaust gas emission pipeline. At this time, this part of the hot water can be used as the vaporization heat source of the first vaporizer 7 and the second vaporizer 9, and as the heat source of the heating device 10 to heat the LNG receiving station.

[0046] Obviously, the above embodiments of the present invention are merely examples for clearly illustrating the present invention, and are not intended to limit the embodiments of the present invention. For those skilled in the art, other different forms of changes or modifications can be made based on the above description. It is not necessary and impossible to list all the embodiments here. Any modifications, equivalent substitutions and improvements made within the spirit and principles of the present invention should be included in the protection scope of the claims of the present invention.

[0047] In the description of the present invention, it should be noted that the terms "center", "up", "down", "left", "right", "vertical", "horizontal", "inside", "outside" and the like indicate positions or positional relationships based on the positions or positional relationships shown in the accompanying drawings, and are only for the convenience of describing the present invention and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore cannot be understood as limiting the present invention. In addition, the terms "first" and "second" are used for descriptive purposes only, and cannot be understood as indicating or implying relative importance. Among them, the terms "first position" and "second position" are two different positions.

[0048] In the description of the present invention, it should be noted that, unless otherwise clearly specified and limited, the terms "installed", "connected", and "connected" should be understood in a broad sense, for example, it can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection or an electrical connection; it can be a direct connection, or it can be indirectly connected through an intermediate medium, or it can be the internal communication of two components. For ordinary technicians in this field, the specific meanings of the above terms in the present invention can be understood according to specific circumstances.

Claims

1. A BOG power generation system for an LNG receiving station, characterized in that: The BOG power generation system of the LNG receiving station includes: An LNG storage tank (1), wherein the LNG storage tank (1) is provided with a BOG outlet; A gas mixing component (4) and a gas turbine (3), wherein the BOG outlet, the gas mixing component (4) and a fuel inlet of the gas turbine (3) are sequentially connected, and the gas mixing component (4) is used to mix the BOG gas entering the gas mixing component (4) from the BOG outlet with gas fuel other than the BOG gas entering the gas mixing component (4), so that the fluctuation amplitude of the calorific value of the mixed gas source formed by the mixture of the BOG gas and the natural gas transported to the gas turbine (3) through the gas mixing component (4) is reduced; The gas mixing component (4) comprises: A fuel gas buffer tank (41), one end of the fuel gas buffer tank (41) being in communication with a fuel inlet of the gas turbine (3); a gas dispersion pipe (42), one end of the gas dispersion pipe (42) being connected to the BOG outlet via a BOG gas power generation pipeline, and the other end of the gas dispersion pipe (42) extending into the gas buffer tank (41); a plurality of gas dispersion holes (421) being provided on the gas dispersion pipe (42); The end of the gas dispersion pipe (42) extending into the gas buffer tank (41) is sealed; The gas buffer tank (41) is provided with an air flow baffle (43) located downstream of the gas dispersion pipe (42), and the air flow baffle (43) is provided with a central hole (44) communicating with an air inlet of the gas buffer tank (41) and an air outlet of the gas buffer tank (41); The air flow baffle (43) comprises a horizontal plate and a vertical plate arranged on one side of the horizontal plate, the vertical plate and the gas dispersion pipe (42) are located on the same side of the horizontal plate, one end of the vertical plate is connected to the horizontal plate, and the other end extends to the side where the gas dispersion pipe (42) is located; the horizontal plate is arranged around the vertical plate to form the central hole (44); The central axis of the central hole (44) coincides with the central axis of the gas dispersion pipe (42); The LNG receiving station BOG power generation system also includes: An LNG tank pump (5) used to extract LNG liquid from the LNG storage tank (1); a first vaporizer (7), wherein the LNG outlet of the LNG tank internal pump (5) is connected to the LNG inlet of the first vaporizer (7), and the natural gas outlet of the first vaporizer (7) is selectively connected to or disconnected from the fuel inlet of the gas mixing component (4); A BOG compressor (2), wherein an inlet and an outlet of the BOG compressor (2) are respectively connected to the BOG outlet and the fuel inlet of the gas mixing component (4).

2. The LNG receiving station BOG power generation system according to claim 1, characterized in that: It also comprises a waste heat recovery heat exchanger (8), wherein the tail gas discharge port of the gas turbine (3) is in communication with the heat source inlet of the waste heat recovery heat exchanger (8).

3. The LNG receiving station BOG power generation system according to claim 2, characterized in that: The medium channel of the waste heat recovery heat exchanger (8) and the heat source channel of the first gasifier (7) can form a first circulation loop.

4. The BOG power generation system for an LNG receiving station according to claim 2, characterized in that: It also comprises a heat exchange device, wherein the medium channel of the waste heat recovery heat exchanger (8) and the heat source channel of the heat exchange device can form a circulation loop.

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