Ammonia storage and supply base

Abstract

To provide an ammonia storage and supply base capable of reducing discard of ammonia which is a fuel even if a thermal power station side which is a demand side is brought into non-stable operation, and capable of securing safe and stable operation at a fuel supply system side.SOLUTION: An ammonia storage and supply base 1 comprises: a cryogenic temperature storage tank 2 for storing liquid ammonia 100 therein; a vaporizer 3 for vaporizing the liquid ammonia 100 dispensed from the cryogenic temperature storage tank 2; a boiler 4 of a thermal power station where gas ammonia vaporized by the vaporizer 3 is burnt while being mixed with coal; a boil-off gas processing facility 5 by which boil-off gas generated in the cryogenic temperature storage tank 2 is re-liquefied and returned to the cryogenic temperature storage tank 2; and a recycle line 6 by which an excessive gas exceeding a consumption quantity of the boiler 4 in the gas ammonia supplied from the vaporizer 3 to the boiler 4 is supplied to the BOG processing facility 5, re-liquefied and returned to the cryogenic temperature storage tank 2.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present invention relates to an ammonia storage and supply terminal. [Background technology]

[0002] The following Patent Document 1 discloses an LNG terminal that supplies natural gas to a thermal power plant. This LNG terminal uses multiple vaporizers to vaporize LNG (liquid fuel) stored at low temperatures in an LNG tank to generate natural gas (gaseous fuel), and delivers the natural gas to the thermal power plant in accordance with its consumption. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Application Publication No. 9-178098 Summary of the Invention [Problem to be solved by the invention]

[0004] The amount of vaporized LNG produced is designed to meet the consumption of the thermal power plant, but depending on the operating conditions of the thermal power plant, the amount of vaporized LNG produced may fall short of the amount consumed by the thermal power plant, resulting in a surplus. In such cases, the surplus vaporized LNG is generally disposed of using a ground flare or other method to mechanically protect the fuel supply system from pressure increases. As is well known, LNG is extremely cold, making it difficult to re-liquefy, and so it must be disposed of by burning it as described above. Furthermore, since the purpose is to protect the equipment mechanically and it is impossible to predict when the above-mentioned unsteady operation will occur, the pilot burner in the ground flare is constantly ignited. Although the amount of fuel consumed by the pilot burner itself may be small, this also means that some of the fuel must be disposed of. In recent years, ammonia, which does not produce carbon dioxide when burned, has been attracting attention as a measure against global warming, and the use of large amounts of liquid ammonia as a new alternative fuel for boilers in thermal power plants is being considered. Against this background, there is a need for an ammonia storage and supply base that can reduce the waste of ammonia as a fuel even when thermal power plants, on the demand side, are in unsteady operation, and that can ensure safe and stable operation on the fuel supply system side. [Means for solving the problem]

[0005] An ammonia storage and supply base according to one embodiment of the present invention includes a low-temperature storage tank that stores liquid ammonia, a vaporizer that vaporizes the liquid ammonia discharged from the low-temperature storage tank, a combustor of a thermal power plant that combusts the gaseous ammonia vaporized by the vaporizer, a boil-off gas treatment facility that re-liquefies boil-off gas produced in the low-temperature storage tank and returns the boil-off gas to the low-temperature storage tank, and a recycle line that supplies surplus gas of the gaseous ammonia supplied from the vaporizer to the combustor that exceeds the amount consumed by the combustor to the boil-off gas treatment facility, where it is re-liquefied and returned to the low-temperature storage tank.

[0006] In addition, one aspect of the present invention may include a gaseous ammonia supply line that supplies gaseous ammonia from the vaporizer to the combustor, and a pressure control device that performs pressure control to open and close the recycle line in accordance with a pressure of the gaseous ammonia supply line.

[0007] In addition, one aspect of the present invention may include a liquid ammonia supply line that supplies liquid ammonia from the low-temperature storage tank to the vaporizer, and a flow rate control device that performs flow rate control to control a flow rate of the liquid ammonia supply line in accordance with an amount of consumption in the combustor.

[0008] In one aspect of the present invention, a plurality of the vaporizers may be provided, and the number of operating vaporizers may be increased or decreased in conjunction with the load on the combustor. [Effects of the Invention]

[0009] According to the above-described aspect of the present invention, even if the thermal power plant on the demand side is in unsteady operation, it is possible to reduce the waste of ammonia as fuel, and also ensure safe and stable operation on the fuel supply system side. [Brief explanation of the drawings]

[0010] [Figure 1] FIG. 1 is a configuration diagram of an ammonia storage and supply base according to an embodiment. DETAILED DESCRIPTION OF THE INVENTION

[0011] Hereinafter, an embodiment of the present invention will be described with reference to the drawings.

[0012] FIG. 1 is a configuration diagram of an ammonia storage and supply base 1 according to one embodiment. The ammonia storage and supply terminal 1 shown in FIG. 1 receives liquid ammonia 100 from a tanker (not shown), stores and vaporizes it, and supplies the vaporized gaseous ammonia to a boiler 4 (combustor) of a thermal power plant. The ammonia storage and supply terminal 1 includes a low-temperature storage tank 2, a vaporizer 3, the boiler 4, a boil-off gas treatment facility (hereinafter referred to as BOG treatment facility 5), and a recycle line 6. The ammonia storage and supply terminal 1 also includes abatement equipment (not shown) that treats ammonia discharged from the terminal. The abatement equipment is an ammonia waste treatment facility that is not normally operated but is used to ensure the safety of the facility (described below).

[0013] The cryogenic storage tank 2 is, for example, a large, double-shelled, above-ground cryogenic tank with a total height of about 50 meters, and a cold insulation material such as granular perlite is filled between an inner tank and an outer tank (not shown). The cryogenic storage tank 2 may also be an underground cryogenic tank. The cryogenic storage tank 2 stores liquid ammonia 100 transferred from an ammonia tanker via a receiving pipe (not shown). The storage temperature of the liquid ammonia 100 is, for example, about -33°C to -34°C.

[0014] Liquid ammonia 100 stored in low-temperature storage tank 2 is supplied to vaporizer 3 via liquid ammonia supply line 7. Liquid ammonia supply line 7 is provided with a discharge pump 8 and a control valve 9. Liquid ammonia supply line 7 is a transfer pipe that connects an ammonia discharge port of discharge pump 8 with an ammonia inlet of vaporizer 3. Discharge pump 8 is an in-tank pump installed inside low-temperature storage tank 2, and discharges liquid ammonia 100 stored in low-temperature storage tank 2 to the outside of the tank.

[0015] The valve opening degree of control valve 9 is controlled in response to a valve opening degree control signal input from flow rate control device 10. Flow rate control device 10 is equipped with a flow meter that measures the flow rate of liquid ammonia supply line 7, and outputs the measurement result to main control device 16, and operates control valve 9 in response to an operation command from control device 16. Control valve 9 is interposed midway along liquid ammonia supply line 7, and adjusts the flow rate of liquid ammonia 100 supplied to vaporizer 3.

[0016] The vaporizer 3 vaporizes liquid ammonia 100 transferred via a liquid ammonia supply line 7 to generate gaseous ammonia. The gaseous ammonia generated in the vaporizer 3 is supplied to a boiler 4 of the thermal power plant via a gaseous ammonia supply line 11. The gaseous ammonia supply line 11 is a transfer pipe that connects a gaseous ammonia outlet of the vaporizer 3 with the boiler 4.

[0017] The boiler 4 mixes the gaseous ammonia vaporized by the vaporizer 3 with coal. The boiler 4 is equipped with multiple burners, and the number of operating burners increases or decreases depending on the mix-firing ratio of gaseous ammonia to coal or the boiler load. The mix-firing ratio of gaseous ammonia is set to a maximum of 20%, for example. Note that multiple vaporizers 3 are also provided, and the number of operating units increases or decreases in conjunction with the mix-firing ratio of gaseous ammonia.

[0018] The BOG treatment equipment 5 re-liquefies boil-off gas (hereinafter referred to as BOG) generated in the low-temperature storage tank 2 due to heat input, etc., and returns the BOG to the low-temperature storage tank 2. The BOG (gaseous ammonia) generated in the low-temperature storage tank 2 is supplied to the BOG treatment equipment 5 via a BOG discharge line 13. The BOG discharge line 13 is a transfer pipe that connects the BOG discharge outlet at the top of the low-temperature storage tank 2 with the BOG inlet of the BOG treatment equipment 5.

[0019] The BOG supplied to the BOG treatment facility 5 is pressurized to a predetermined pressure by the BOG compressor and liquefied with cooling water in the BOG condenser. The liquefied ammonia is partially cooled in an economizer, then passes through an expansion valve and the BOG return line 14, and is returned to the low-temperature storage tank 2. In this way, the BOG treatment facility 5 treats (re-liquefies) the BOG generated from the low-temperature storage tank 2, and maintains the pressure of the low-temperature storage tank 2 constant.

[0020] Of the gaseous ammonia supplied from vaporizer 3 to boiler 4, recycle line 6 supplies surplus gas that exceeds the amount consumed by boiler 4 to BOG treatment equipment 5 to be re-liquefied and returned to low-temperature storage tank 2. Recycle line 6 is a transfer pipe that connects gaseous ammonia supply line 11 and BOG discharge line 13. In other words, the gaseous ammonia that has passed through recycle line 6 is returned from the downstream side (secondary side) of vaporizer 3 to the upstream side (primary side) of BOG treatment equipment 5.

[0021] A control valve 15 is provided in the recycle line 6. The valve opening of the control valve 15 is controlled in response to a valve opening control signal input from the pressure control device 12. The pressure control device 12 is equipped with a pressure gauge that measures the pressure of the gaseous ammonia supply line 11, and outputs the measurement result to a main control device 16, and operates the control valve 15 in response to an operation command from the control device 16. The control valve 15 is interposed midway along the recycle line 6, and adjusts the flow rate of gaseous ammonia returned to the BOG treatment facility 5 by opening and closing the recycle line 6.

[0022] Control device 16 switches between burner pressure control and burner flow rate control depending on the fuel demand of boiler 4 of the thermal power plant. When the operating rate of the burner of boiler 4 (mixed combustion rate of gaseous ammonia) is low (at the beginning of operation of boiler 4), the flow rate of liquid ammonia supply line 7 is low and measurement by the flow meter of flow rate control device 10 becomes impossible or difficult, so control device 16 performs burner pressure control.

[0023] Burner pressure control is a control that adjusts the valve opening of control valve 15 of recycle line 6 according to the required pressure of gaseous ammonia on the side of boiler 4. For example, control valve 15 of recycle line 6 is closed (valve opening zero) until the pressure of gaseous ammonia supply line 11 reaches the required pressure, and when the pressure of gaseous ammonia supply line 11 gradually increases, control valve 15 of recycle line 6 is opened according to the difference with the required pressure.

[0024] Furthermore, when the operating rate of the burner of boiler 4 (mixed combustion rate of gaseous ammonia) becomes high (when the flow rate of liquid ammonia supply line 7 becomes sufficient), control device 16 switches from burner pressure control to burner flow rate control. Burner pressure control is a control that adjusts the valve opening of control valve 9 for liquid ammonia 100 according to the demand for gaseous ammonia on the boiler 4 side.

[0025] Depending on the operating conditions of the thermal power plant, the amount of vaporized ammonia demanded by the thermal power plant may fall short of the amount generated, resulting in a surplus. In this case, control device 16 narrows the valve aperture of control valve 9 on liquid ammonia supply line 7 to reduce the amount of liquid ammonia 100 supplied to vaporizer 3, and opens control valve 15 on recycle line 6 to return the surplus gaseous ammonia generated in vaporizer 3 to BOG treatment facility 5. The gaseous ammonia returned to BOG treatment facility 5 is re-liquefied without being discarded, and returned to low-temperature storage tank 2.

[0026] As described above, the ammonia storage and supply base 1 of the present embodiment includes: a low-temperature storage tank 2 that stores liquid ammonia 100; a vaporizer 3 that vaporizes the liquid ammonia 100 discharged from the low-temperature storage tank 2; a boiler 4 of a thermal power plant that mixes coal with the gaseous ammonia vaporized by the vaporizer 3; a BOG treatment facility 5 that re-liquefies the boil-off gas produced in the low-temperature storage tank 2 and returns it to the low-temperature storage tank 2; and a recycle line 6 that supplies surplus gas of the gaseous ammonia supplied from the vaporizer 3 to the boiler 4 that exceeds the amount consumed by the boiler 4 to the BOG treatment facility 5, where it is re-liquefied and returned to the low-temperature storage tank 2.

[0027] This configuration allows for the vaporization of large volumes of liquid ammonia 100 as fuel for thermal power generation. Furthermore, the provision of a recycle line 6 eliminates the need to dispose of excess gaseous ammonia. Because gaseous ammonia is toxic and cannot be burned using ground flares, as with natural gas, without the provision of a recycle line 6, the safe disposal of excess gaseous ammonia would require increasing the operating rate of the abatement equipment, which is normally not required to operate, and increasing the capacity of the abatement equipment. The abatement equipment contains water to dissolve the gaseous ammonia. The heat of dissolution of ammonia increases the water temperature in the tank. Furthermore, ammonia water is considered a toxic substance when its concentration exceeds 10 wt%, so a large amount of water must be stored. In other words, the provision of a recycle line 6 eliminates the need to enlarge the abatement equipment to ensure a stable supply of gaseous ammonia to the thermal power plant.

[0028] The ammonia storage and supply terminal 1 of this embodiment utilizes the concept of a conventional LNG vaporization and supply facility, while taking into account the characteristics of ammonia. By adding a single recycle line 6, the entire facility can be optimized, while stably satisfying the overall operating range of the demanding thermal power plant. Furthermore, since the flow rate control device 10 and the pressure control device 12 are provided and the amount of gaseous ammonia recycled is small, the diameter of the additional piping is small, so the initial cost of installing the recycle line 6 is small. Furthermore, there is no need to reassess the capacity of the BOG treatment facility 5, which leads to an optimized design. Furthermore, by providing multiple vaporizers 3 and adjusting the number of operating units in conjunction with the gaseous ammonia co-firing ratio in the boiler 4, an optimal combination of the number of units can be achieved, taking into account the operating load tolerance (turndown range) of the vaporizers 3.

[0029] As described above, according to the ammonia storage and supply base 1 of the present embodiment, even if the thermal power plant on the demand side is in unsteady operation, it is possible to reduce the amount of ammonia waste, which is the fuel, and ensure safe and stable operation on the fuel supply system side. Furthermore, since the amount of ammonia waste can be reduced, the capacity of the abatement equipment can also be minimized.

[0030] While preferred embodiments of the present invention have been described and illustrated, it should be understood that these are illustrative of the present invention and should not be considered as limiting. Additions, omissions, substitutions, and other modifications can be made without departing from the scope of the present invention. Accordingly, the present invention should not be deemed limited by the foregoing description, but rather by the scope of the claims.

[0031] In the above embodiment, the combustor is exemplified as boiler 4 of a thermal power plant that mixes gaseous ammonia vaporized by vaporizer 3 with coal, but is not limited to this configuration. The combustor may be, for example, a boiler of a thermal power plant that uses only gaseous ammonia as fuel. In this case, the number of operating units of vaporizer 3 may be increased or decreased in conjunction with the load of the boiler. The combustor may also be a gas turbine in a thermal power plant that uses gaseous ammonia as fuel. [Explanation of symbols]

[0032] 1...Ammonia storage and supply base, 2...Low temperature storage tank, 3...Vaporizer, 4...Boiler, 5...BOG treatment equipment, 6...Recycle line, 7...Liquid ammonia supply line, 8...Discharge pump, 9...Control valve, 10...Flow rate control device, 11...Gaseous ammonia supply line, 12...Pressure control device, 13...BOG discharge line, 14...BOG return line, 15...Control valve, 16...Control device, 100...Liquid ammonia

Claims

1. a cryogenic storage tank for storing liquid ammonia; a vaporizer that vaporizes the liquid ammonia discharged from the low-temperature storage tank; a combustor of a thermal power plant that burns the gaseous ammonia vaporized by the vaporizer; a boil-off gas treatment facility that re-liquefies the boil-off gas generated in the low-temperature storage tank and returns the boil-off gas to the low-temperature storage tank; A recycle line that supplies surplus gas of gaseous ammonia supplied from the vaporizer to the combustor, which exceeds the amount consumed by the combustor, to the boil-off gas treatment facility to be re-liquefied and returned to the low-temperature storage tank; a gaseous ammonia supply line that supplies gaseous ammonia from the vaporizer to the combustor; a pressure control device that opens and closes the recycle line in accordance with the pressure of the gaseous ammonia supply line, and controls the pressure; An ammonia storage and supply base comprising:

2. a cryogenic storage tank for storing liquid ammonia; a vaporizer that vaporizes the liquid ammonia discharged from the low-temperature storage tank; a combustor of a thermal power plant that burns the gaseous ammonia vaporized by the vaporizer; a boil-off gas treatment facility that re-liquefies the boil-off gas generated in the low-temperature storage tank and returns the boil-off gas to the low-temperature storage tank; A recycle line that supplies surplus gas of gaseous ammonia supplied from the vaporizer to the combustor, which exceeds the amount consumed by the combustor, to the boil-off gas treatment facility to be re-liquefied and returned to the low-temperature storage tank; a liquid ammonia supply line that supplies liquid ammonia from the low-temperature storage tank to the vaporizer; a flow rate control device that controls a flow rate of the liquid ammonia supply line in accordance with the consumption amount of the combustor; An ammonia storage and supply base comprising:

3. 3. The ammonia storage and supply base according to claim 1, wherein a plurality of the vaporizers are provided, and the number of operating vaporizers increases or decreases in conjunction with the load of the combustor.

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