DE-112024002478-T5 - COMBINED POWER GENERATION SYSTEM AND COMBINED POWER GENERATION PROCESS

Abstract

In a combined power generation system (1A), a first power generation unit (2) generates first electricity using steam, and a second power generation unit (3) uses a portion of the steam to supply liquid ammonia to a turbine drive fluid, which is then used to drive an ammonia turbine (20) to generate second electricity. Exhaust ammonia from the second power generation unit (3) is combusted, and the heat of combustion is utilized. The turbine drive fluid is superheated ammonia gas or a supercritical ammonia liquid produced by heating liquid ammonia in a power addition device (16) contained within the second power generation unit (3).

Inventors

• Yoshiaki Yamashita
• Takahiro Miyamoto

Assignees

• TOKUYAMA CORPORATION

Dates

Publication Date

20260513

Application Date

20240514

Priority Date

20230609

Claims (8)

1. Combined power generation system comprising: a first power generation plant including: a boiler device configured to generate steam, at least one steam turbine driven by the steam, and a first generator connected to the at least one steam turbine to generate electricity; and comprising a second power generating plant: a storage device configured to store liquid ammonia, an energy addition device configured to add the liquid ammonia supplied by the storage device to a turbine driving fluid using residual heat from exhaust steam of at least one steam turbine, an ammonia turbine capable of being driven by the turbine driving fluid produced by the energy addition device, and a second generator connected to the ammonia turbine to generate electricity, the combined power generating system causing exhaust ammonia from the ammonia turbine to be combusted in the boiler device or in at least one part of predetermined device other than the boiler device, and the at least one part of predetermined device comprising a combustion chamber configured to combust the exhaust ammonia.
2. Combined power generation system according to Claim 1 , whereby the ammonia exhaust gas is burned in the boiler device.
3. Combined power generation system according to Claim 1 or Claim 2 , which also includes: a pressure generating device configured to bring the liquid ammonia to be supplied to the energy addition device to a pressure greater than or equal to 6 MPaG.
4. Combined power generation system according to Claim 1 or Claim 2 , wherein the at least one steam turbine comprises: a medium-pressure steam turbine configured to deliver medium-pressure exhaust steam with an outlet temperature of 200 to 450 °C, a low-pressure steam turbine configured to deliver low-pressure exhaust steam with an outlet temperature of 30 to 200 °C, wherein the energy addition device is an ammonia vaporization device comprising: a preheater configured to preheat the liquid ammonia, an evaporator configured to vaporize the liquid ammonia preheated by the preheater, and a superheater configured to superheat the ammonia gas produced by the evaporator by vaporization, wherein the combined power generation system further comprises: a medium-pressure exhaust steam supply line configured to feed a portion of the medium-pressure exhaust steam to the superheater and a portion of the medium-pressure exhaust steam at a reduced temperature in the superheater to the evaporator, and a hot water supply line configured to supply at least one of the first hot water or the second hot water to the preheater, wherein the first hot water is generated by the evaporator or a device associated with the evaporator and the second heated water is generated by a device associated with the low-pressure steam turbine.
5. Combined power generation system according to Claim 1 , wherein the combined power generation system supplies the ammonia exhaust gas from the ammonia turbine to the boiler device or to the at least one predetermined piece of equipment using the residual pressure of the ammonia exhaust gas.
6. Combined power generation system according to Claim 1 , where the liquid ammonia contains less than or equal to 1 percent water by mass.
7. Combined power generation system according to Claim 6 , wherein the ammonia exhaust gas supplied to a combustion chamber contained in the boiler apparatus or the at least one predetermined piece of equipment has a temperature greater than or equal to 18.8 °C.
8. A combined power generation process comprising: driving a steam turbine connected to a first generator using steam generated by the boiler device to produce a first stream; generating a turbine driving fluid from liquid ammonia using residual heat from the exhaust gas of the steam turbine and driving an ammonia turbine connected to a second generator using the turbine driving fluid to produce a second stream; and burning the ammonia exhaust gas from the ammonia turbine in the boiler device or the at least one predetermined sub-device other than the boiler device.

Description

BACKGROUND OF THE INVENTION Field of invention The present invention relates to a combined power generation system and a combined power generation method by which liquid ammonia can be vaporized to produce ammonia gas for combustion with little or no energy loss. State of the art Ammonia ( NH₃ ), which is gaseous at room temperature (20 °C with a vapor pressure of 0.875 MPaG), can typically be easily liquefied when cooled or pressurized and can be transported or stored in its liquid state for use as a fuel. Ammonia therefore incurs lower transportation and storage costs than gaseous fuels that are not easily liquefied. Ammonia has also recently attracted attention as a fuel that does not emit carbon dioxide ( CO₂ ), a greenhouse gas, when burned. Well-known thermal power generation plants partially replace fossil fuels such as coal with ammonia in order to reduce the emission of carbon dioxide as a greenhouse gas. In order to use ammonia as fuel, liquid ammonia must be vaporized to ammonia gas. Ammonia has a boiling point of -33.34 °C, which is far below the boiling point of water. Liquid ammonia can therefore be easily evaporated using process water or seawater as a heating medium. However, using process water or seawater as a heating medium for the vaporization of liquid ammonia will likely result in increased energy costs for pumping this water. Considering the energy balance, using ammonia as a fuel may be less cost-effective. In response, well-known plants such as thermal power plants use residual heat to evaporate liquid ammonia for use as fuel. As a related application in this technical field, patent literature 1 describes, for example, an ammonia supply unit for a power plant, a method for evaporating ammonia for a power plant, and a power plant. QUOTE LIST PATENT LITERATURE Patent Literature 1: Japanese Unexamined Patent Application No. 2023-11172 SUMMARY OF THE INVENTION TECHNICAL PROBLEM In the invention described in patent literature 1, a known plant, for example a thermal power generation plant, uses waste heat to produce ammonia gas for combustion, thereby minimizing energy loss during vaporization. However, such a plant has only a limited amount of waste heat available. Therefore, only a limited amount of liquid ammonia can be evaporated using the method described in patent literature 1. Under the above-mentioned circumstances and with the known technology, one or more aspects of the present invention relate to a combined power generation system and a combined power generation method with which a large quantity of liquid ammonia can be vaporized to produce ammonia gas for combustion, with less or no energy loss occurring during vaporization. SOLUTION TO THE PROBLEM In response to the problem mentioned above, a combined power generation system, according to a first aspect, comprises a first power generation plant and a second power generation plant. The first power generation plant includes a boiler device that generates steam, at least one steam turbine driven by the steam, and a first generator connected to the at least one steam turbine to generate electricity. The second power generation plant includes a storage device that stores liquid ammonia, an energy addition device that, using residual heat from exhaust steam from the at least one steam turbine, adds the liquid ammonia from the storage device to a turbine driving fluid, an ammonia turbine driven by the turbine driving fluid generated by the energy addition device, and a second generator connected to the ammonia turbine to generate electricity. The combined power generation system causes exhaust ammonia from the ammonia turbine to be burned in the boiler device or in at least part of a predetermined device other than the boiler device, and which includes at least one sub-device comprising a combustion chamber that burns the exhaust ammonia. In the structure according to the first aspect, the first power generating plant drives the steam turbine using steam generated by the boiler device, and generates the first electricity with the first generator connected to the steam turbine. In the second power generation unit, the energy addition device feeds liquid ammonia from the storage device into the turbine drive fluid (superheated ammonia gas or supercritical ammonia liquid) using residual heat from the exhaust steam of the steam turbine in the first power generation unit. The second power generation unit then drives the ammonia turbine using the turbine drive fluid produced by the energy addition device and generates the second electricity with the second generator connected to the ammonia turbine. Furthermore, the exhaust ammonia from the ammonia turbine is used in the second power generation plant as ammonia gas for combustion in the boiler device or in at least one sub-device that is not the boiler device. In other words, in the system described in the first aspect, the first power generation plant produces the first electricity usin