Waste combustion power generation device and waste combustion power generation method

Abstract

The present invention relates to a waste combustion power generation device which generates combustion exhaust gas by combusting waste, obtains superheated steam by using heat of the combustion exhaust gas, and drives a steam turbine with the superheated steam. This waste combustion power generation device is provided with: a combustion furnace (11); a waste heat boiler (13) in which a superheater (21) and a high-temperature heat exchanger (12) are incorporated; an independent superheater (14) that heats the superheated steam by exchanging heat between the superheated steam and the heated fluid; a circulation line (25) that circulates a fluid between the high-temperature heat exchanger (12) and the independent superheater (14); and a generator (15) having a steam turbine to which superheated steam heated by the independent superheater (14) is supplied. The high-temperature heat exchanger (12) is provided with at least a plurality of high-temperature fluid heating tubes (35) that penetrate the side walls (13a, 13b) of the waste heat boiler (13) and extend across the flow path of the combustion exhaust gas.

Description

Technical Field

[0001] The present invention relates to a waste combustion power generation device and a waste combustion power generation method, which generates combustion exhaust by burning waste, utilizes the heat of the combustion exhaust to obtain superheated steam, and uses the superheated steam to drive a steam turbine. Background Art

[0002] Heat recovery methods are known that utilize the heat energy generated by the combustion of waste (e.g., various types of garbage) for power generation. For example, in the waste combustion power generation device described in Patent Document 1, the high-temperature combustion exhaust gas generated by the combustion of waste is directed to a high-temperature heat exchanger, where the gas is heated and supplied to a superheated steam superheater (hereinafter referred to as an "independent superheater"). In the independent superheater, the heated gas serves as a heat source to raise the temperature of the superheated steam, which is then supplied to a steam turbine. The steam turbine is connected to a generator, which uses the heated superheated steam to drive the steam turbine, thereby generating electricity.

[0003] In recent years, there has been a demand for highly efficient energy recovery in waste combustion. Therefore, even in waste combustion power plants such as those described in Patent Document 1, it is desirable to maintain the temperature of the heating gas used to heat the superheated steam at a stable high temperature (e.g., 700°C or higher) and to supply superheated steam at a desired temperature (e.g., 500°C or higher) to the steam turbine.

[0004] Prior art literature

[0005] Patent Literature

[0006] Patent Document 1: Japanese Patent Application Laid-Open No. 2000-297613 Summary of the Invention

[0007] However, in conventional waste-to-energy power plants, the high-temperature exchangers have multiple heat exchangers with a double-tube structure protruding from the wall surface that forms the flow path for the high-temperature combustion exhaust gas. The gas to be heated flows within the double-tube heat exchanger. With this structure, the gas flowing within the double-tube heat exchanger cannot efficiently exchange heat with the high-temperature combustion exhaust gas flowing within the flow path, making it difficult to maintain a stable high temperature for the heating gas used to heat the superheated steam. Furthermore, the temperature of the double-tube heat exchanger itself may not be raised to the desired level, and the double-tube heat exchanger contained in the combustion exhaust gas may be corroded by low-temperature corrosive salts.

[0008] Therefore, the present invention provides a waste combustion power generation device and a waste combustion power generation method, which can improve the heat exchange efficiency between the fluid flowing in the high-temperature heat exchanger and the combustion exhaust gas, and supply the gas heated to a temperature above the desired temperature to an independent superheater for reheating the superheated steam.

[0009] In one embodiment, a waste combustion power generation device is provided, comprising: a combustion furnace that burns waste; a waste heat boiler that has a built-in superheater that generates superheated steam from saturated steam by exchanging heat between the combustion exhaust gas from the combustion furnace and saturated steam; and a high-temperature heat exchanger that heats the fluid by exchanging heat between the combustion exhaust gas from the combustion furnace and the fluid; an independent superheater that raises the temperature of the superheated steam by exchanging heat between the superheated steam and the heated fluid; a circulation line that circulates the fluid between the high-temperature heat exchanger and the independent superheater; and a generator having a steam turbine supplied with the superheated steam raised in temperature by the independent superheater, the high-temperature heat exchanger having at least a plurality of high-temperature fluid heating pipes that penetrate a side wall of the waste heat boiler and extend across a flow path of the combustion exhaust gas.

[0010] In one embodiment, the waste heat boiler includes a heat-resistant panel mounted on an inner surface of a side wall of the high-temperature heat exchanger through which a high-temperature fluid heating pipe passes.

[0011] In one embodiment, the high-temperature heat exchanger includes a pressure wave soot blower that imparts vibration to the high-temperature fluid heating pipe.

[0012] In one embodiment, the waste incineration power generation device further includes a triatomic molecule supply line connected to the circulation line for supplying triatomic molecules to the fluid flowing in the circulation line.

[0013] In one embodiment, a waste combustion power generation method is provided, which includes the following contents: burning waste to generate combustion exhaust gas; performing heat exchange between the combustion exhaust gas and saturated steam through a superheater built into a waste heat boiler, and generating superheated steam from the saturated steam; performing heat exchange between the combustion exhaust gas and a fluid through a high-temperature heat exchanger built into the waste heat boiler, thereby heating the fluid; circulating the fluid between the high-temperature heat exchanger and an independent superheater; supplying the superheated steam to the independent superheater, performing heat exchange between the superheated steam and the fluid, thereby heating the superheated steam; and supplying the heated superheated steam to a steam turbine to generate electricity, the high-temperature heat exchanger having at least a plurality of high-temperature fluid heating pipes, the plurality of high-temperature fluid heating pipes penetrating the side wall of the waste heat boiler and extending across the flow path of the combustion exhaust gas.

[0014] In one embodiment, heat exchange is performed between the fluid and the combustion exhaust gas while the high-temperature fluid heating pipe is thermally insulated from the side wall of the waste heat boiler by a heat-resistant panel attached to the inner surface of the waste heat boiler.

[0015] In one embodiment, the high-temperature heat exchanger includes a pressure wave soot blower that periodically applies vibration to the high-temperature fluid heating pipe.

[0016] In one embodiment, triatomic molecules are supplied to the fluid, and the fluid containing the triatomic molecules is heated by the high-temperature heat exchanger.

[0017] Effects of the Invention

[0018] The high-temperature fluid heating tubes extend completely across the flow path of the high-temperature combustion exhaust gas from the waste heat boiler. Therefore, when heat is exchanged between the fluid flowing through the high-temperature fluid heating tubes and the high-temperature combustion exhaust gas flowing through the waste heat boiler, the exhaust gas flows evenly around the multiple high-temperature fluid heating tubes. As a result, the heat exchange efficiency between the fluid supplied to the independent superheater and the exhaust gas is gradually improved, allowing for a stable supply of fluid heated to a temperature above the desired level to the independent superheater. BRIEF DESCRIPTION OF THE DRAWINGS

[0019] Figure 1 A schematic diagram showing a waste incineration power generation device according to one embodiment.

[0020] Figure 2 A schematic diagram showing the periphery of a high-temperature heat exchanger according to one embodiment.

[0021] Figure 3 A schematic diagram showing the high-temperature fluid heating tubes of the high-temperature heat exchanger and the side wall of the waste heat boiler. DETAILED DESCRIPTION

[0022] Hereinafter, embodiments of the present invention will be described with reference to the accompanying drawings.

[0023] Figure 1 A schematic diagram showing a waste incineration power generation device according to one embodiment. Figure 1 The waste-to-energy power generation system shown includes: a combustion furnace 11, which burns waste (e.g., garbage); a waste heat boiler 13, which recovers heat energy from the combustion exhaust; an independent superheater (superheated steam superheater) 14, which heats the superheated steam generated by heat exchange in the waste heat boiler 13; and a steam turbine generator 15, which is connected to the independent superheater 14. The combustion furnace 11 is a device for burning and treating waste, and emits high-temperature combustion exhaust (e.g., exhaust having a temperature of 850°C or above). In one embodiment, the waste-to-energy power generation system may also include a gasification and melting furnace in place of the combustion furnace 11.

[0024] Figure 1The waste combustion power generation device shown further includes: an exhaust gas treatment device 16, which renders the combustion exhaust gas passing through the waste heat boiler 13 harmless for release into the atmosphere; and a chimney 20, which is used to release the combustion exhaust gas passing through the exhaust gas treatment device 16 into the atmosphere. The structure and type of the exhaust gas treatment device 16 are arbitrary, as long as it can render the combustion exhaust gas harmless. For example, the exhaust gas treatment device 16 may also include: an air preheater, which preheats the air supplied to the combustion furnace 11; an economizer, which preheats the water used to generate superheated steam in the waste heat boiler 13; and a dust collector (such as a bag filter) for capturing ash contained in the combustion exhaust gas. The air preheater and the economizer can reduce the temperature of the combustion exhaust gas.

[0025] The waste heat boiler 13 includes a superheater 21 for generating superheated steam from saturated steam using combustion exhaust gas, and a high-temperature heat exchanger 12 for supplying a high-temperature fluid (such as air) to the independent superheater 14. The detailed structure of the waste heat boiler 13 will be described later.

[0026] Figure 1 The waste combustion power plant shown further includes: an independent superheater 14; a circulation line 25 for circulating fluid between the independent superheater 14 and the high-temperature heat exchanger 12 of the waste heat boiler 13; and a circulation device 31 (e.g., a circulation fan) disposed in the circulation line 25. The fluid flowing in the circulation line 25 is sent by the circulation device 31 to the high-temperature heat exchanger 12, where it exchanges heat with combustion exhaust gas and is heated to a high temperature. The fluid passing through the high-temperature heat exchanger 12 is sent to the independent superheater 14, where it exchanges heat with superheated steam and is cooled, and then returned to the high-temperature heat exchanger 12 by the circulation device 31. In this manner, the fluid flowing in the circulation line 25 circulates between the independent superheater 14 and the high-temperature heat exchanger 12.

[0027] The fluid circulating between the high-temperature heat exchanger 12 and the independent superheater 14 via the circulation line 25 is heated to a desired temperature (e.g., 700°C) or higher by heat from the combustion exhaust gas while circulating between these devices 12 and 14. Examples of the fluid flowing within the circulation line 25 include gases such as air. However, any type of fluid may be used as long as it can be heated to a desired temperature or higher by the high-temperature heat exchanger 12, and a mixture of multiple fluids may also be used.

[0028] Figure 1The waste combustion power generation system shown operates as follows. Waste is supplied from a feeder (not shown) to a combustion furnace 11, where it is combusted and processed, generating high-temperature combustion exhaust gas. This exhaust gas is supplied to a waste heat boiler 13. Passing through a high-temperature heat exchanger 12 built into the waste heat boiler 13, it exchanges heat with the fluid flowing in a circulation line 25, raising the fluid's temperature to a desired level (e.g., 700°C or higher). The fluid, heated to the desired temperature, is then supplied to an independent superheater 14 via the circulation line 25.

[0029] On the other hand, the saturated steam supplied to the superheater 21 built into the waste heat boiler 13 exchanges heat with the combustion exhaust gas in the superheater 21 to generate superheated steam. This superheated steam has a mass fraction of, for example, 100 kg / cm 2 The superheated steam is heated to a desired temperature (e.g., 500°C) or higher by exchanging heat with the fluid supplied to the independent superheater 14 and circulating in the circulation line 25. This superheated steam is supplied to the steam turbine generator 15 to generate electricity. The combustion exhaust gas discharged from the waste heat boiler 13 is rendered harmless by the exhaust gas treatment device 16 and discharged as clean air from the chimney 20.

[0030] Figure 2 A schematic diagram showing the periphery of a high-temperature heat exchanger according to one embodiment, Figure 3 A schematic diagram showing the high-temperature fluid heating pipes of the high-temperature heat exchanger and the side wall of the waste heat boiler. Figure 2 As shown, the waste heat boiler 13 is provided with multiple partition walls 30 that form a combustion exhaust gas flow path, and the high-temperature heat exchanger 12 is disposed between adjacent partition walls 30. In this embodiment, to prevent damage to the partition walls 30 due to the heat of the combustion exhaust gas, the partition walls 30 are configured as cooling panels with multiple boiler water pipes disposed therein for the flow of boiler water.

[0031] The high temperature heat exchanger 12 includes at least a plurality of high temperature fluid heating pipes 35 for the fluid to be heated to flow. Figure 3 As shown, each high-temperature fluid heating pipe 35 extends through the opposing side walls 13a and 13b of the waste heat boiler 13. In this embodiment, each high-temperature fluid heating pipe 35 extends horizontally parallel to one another. Furthermore, each high-temperature fluid heating pipe 35 extends from a pipe head (not shown) to ensure uniform flow of fluid within each high-temperature fluid heating pipe 35. This pipe head is located in the circulation line 25.

[0032] Multiple boiler water pipes 33, through which boiler water flows, are densely arranged on the side walls 13a and 13b of the waste heat boiler 13, forming a cooling water panel. This structure prevents damage to the side walls 13a and 13b of the waste heat boiler 13 due to the high-temperature combustion exhaust gas flowing through the waste heat boiler 13. Meanwhile, the boiler water flowing through the boiler water pipes 33 is heated by the high-temperature combustion exhaust gas, becoming saturated steam. This saturated steam is then supplied to the superheater 21 and becomes superheated steam.

[0033] According to this structure, because the high-temperature fluid heating pipes 35 extend completely across the high-temperature combustion exhaust gas flow path formed in the waste heat boiler 13, when heat is exchanged between the fluid flowing through the high-temperature fluid heating pipes 35 and the high-temperature combustion exhaust gas flowing through the waste heat boiler 13, the combustion exhaust gas flows evenly around the plurality of high-temperature fluid heating pipes 35. As a result, the heat exchange efficiency between the fluid flowing through the high-temperature fluid heating pipes 35 (i.e., the fluid supplied to the independent superheater 14) and the combustion exhaust gas is gradually improved, and the fluid heated to a desired temperature or above can be stably supplied to the independent superheater 14.

[0034] Furthermore, according to this embodiment, corrosion and thinning of the high-temperature fluid heating pipe 35 can be effectively suppressed, reducing the maintenance frequency of the waste heat boiler 13 and, more generally, the waste combustion power generation device. Specifically, the ash generated during waste combustion contains salts that corrode the piping (hereinafter referred to as "corrosive salts"). Meanwhile, the temperature of the high-temperature fluid heating pipe 35 is heated by the combustion exhaust gas to a level sufficient to heat the fluid flowing therein to a temperature exceeding 700°C. Therefore, even if the ash containing the corrosive salts adheres to the high-temperature fluid heating pipe 35, the corrosive salts can be sublimated, preventing the corrosive salts from becoming fixed to the high-temperature fluid heating pipe 35. As a result, damage to the high-temperature fluid heating pipe 35 caused by the corrosive salts can be effectively suppressed. Furthermore, because the high-temperature fluid heating pipe 35 can be a straight pipe without welded portions, welded portions with low corrosion resistance can be eliminated from the high-temperature fluid heating pipe 35. From this perspective, damage to the high-temperature fluid heating pipe 35 caused by the corrosive salts can also be effectively suppressed.

[0035] like Figure 3As shown, heat-resistant panels (or fire-resistant panels) 36 are installed on the inner surfaces of the side walls 13a and 13b of the waste heat boiler 13. The heat-resistant panels 36 prevent the boiler water flowing through the boiler water pipes 33 disposed in the side walls 13a and 13b of the waste heat boiler 13 from cooling the high-temperature fluid heating pipes 35. More specifically, the heat-resistant panels 36 prevent the high-temperature fluid heating pipes 35 from cooling the portion of the waste heat boiler 13 through which they pass. In other words, the heat-resistant panels 36 effectively prevent the high-temperature fluid heating pipes 35 and the fluid flowing therein from decreasing in temperature, effectively raising the fluid temperature to the desired level. Furthermore, because the heat-resistant panels 36 maintain the high-temperature fluid heating pipes 35 at a stable high temperature, ash containing the aforementioned corrosive salts can be more effectively prevented from adhering to the high-temperature fluid heating pipes 35.

[0036] In one embodiment, the high temperature heat exchanger 12 may also have a pressure wave soot blower 38 (see Figure 2 The pressure wave soot blower 38 utilizes pressure waves (e.g., supersonic pressure waves) generated by igniting a mixture of combustible gases such as natural gas and methane with oxygen to cause subtle vibrations in the ash containing corrosive salts adhering to the surface of the high-temperature fluid heating tube 35. By periodically operating the pressure wave soot blower 38 (e.g., every few hours), the ash containing corrosive salts can be effectively removed from the surface of the high-temperature fluid heating tube 35. As a result, corrosion thinning of the high-temperature fluid heating tube 35 is further effectively suppressed.

[0037] like Figure 1 As shown, the waste incineration power generation device may also include a triatomic molecule supply line 40 connected to the circulation line. The triatomic molecule supply line 40 extends from a triatomic molecule supply source (not shown) and supplies triatomic molecules to the fluid flowing in the circulation line 25 in an appropriate amount and at an appropriate timing. Although not shown, a flow meter and an on-off valve may be provided in the triatomic molecule supply line 40.

[0038] Triatomic molecules are molecules that can efficiently conduct heat through thermal radiation. Therefore, when triatomic molecules are supplied to the fluid flowing in circulation line 25 via triatomic molecule supply line 40 in an appropriate amount and at an appropriate timing, the supplied triatomic molecules can more efficiently heat the fluid flowing in circulation line 25 through radiation. As a result, the fluid can be efficiently and quickly heated to a desired temperature.

[0039] Water and carbon dioxide are listed as examples of triatomic molecules. As a triatomic molecule, water is preferred from the perspectives of ease of use and handling. When the triatomic molecule supplied from the triatomic molecule supply line 40 to the circulation line 25 is water, a sprayer (not shown) is provided at the front end of the triatomic molecule supply line to supply misted water (or water vapor) to the fluid flowing in the circulation line 25. For example, water is supplied until the amount of water vapor saturates the fluid flowing in the circulation line 25.

[0040] The above embodiments are described for the purpose of enabling those skilled in the art to implement the present invention. Those skilled in the art can, of course, create various variations of the above embodiments, and the technical concepts of the present invention may also be applied to other embodiments. Therefore, the present invention is not limited to the described embodiments but is to be interpreted broadly based on the technical concepts defined in the technical solutions.

[0041] Industrial Applicability

[0042] The present invention is a waste combustion power generation device and a waste combustion power generation method that can be used to obtain high-temperature and high-pressure superheated steam using the heat of the combustion exhaust gas generated by burning waste. The superheated steam drives a steam turbine to generate electricity.

[0043] Description of Reference Numerals

[0044] 11: Combustion furnace

[0045] 12: High temperature heat exchanger

[0046] 13: Waste heat boiler

[0047] 13a, 13b: Side walls

[0048] 14: Independent superheater

[0049] 15: Steam turbine generator

[0050] 16: Exhaust treatment device

[0051] 20: Chimney

[0052] 21: Superheater

[0053] 25: Circulation pipeline

[0054] 30: Partition wall

[0055] 31: Circulation device

[0056] 33: Boiler water pipe

[0057] 35: High temperature fluid heating tube

[0058] 36: Heat-resistant panel

[0059] 38: Pressure wave soot blower

[0060] 40: Triatomic molecule supply pipeline.

Claims

1. A waste combustion power generation device, wherein: have: a combustion furnace, which burns the waste; a waste heat boiler having a built-in superheater for generating superheated steam from saturated steam by exchanging heat between the combustion exhaust gas from the combustion furnace and the saturated steam; and a high-temperature heat exchanger for heating the fluid by exchanging heat between the combustion exhaust gas from the combustion furnace and the fluid; an independent superheater for increasing the temperature of the superheated steam by exchanging heat between the superheated steam and the heated fluid; a circulation line for circulating the fluid between the high-temperature heat exchanger and the independent superheater; as well as a generator having a steam turbine supplied with superheated steam heated by the independent superheater, The high-temperature heat exchanger has at least a plurality of high-temperature fluid heating pipes, which penetrate the side wall of the waste heat boiler and extend across the flow path of the combustion exhaust gas.

2. The waste combustion power generation device according to claim 1, wherein: The waste heat boiler has a heat-resistant panel, which is installed on the inner surface of the side wall through which the high-temperature fluid heating pipe of the high-temperature heat exchanger passes.

3. The waste combustion power generation device according to claim 1, wherein: The high-temperature heat exchanger has a pressure wave soot blower that imparts vibration to the high-temperature fluid heating pipe.

4. The waste combustion power generation device according to any one of claims 1 to 3, wherein: The invention further includes a triatomic molecule supply line connected to the circulation line for supplying triatomic molecules to the fluid flowing in the circulation line.

5. A method for power generation by burning waste, wherein: It has the following contents: Burning waste and generating combustion exhaust; generating superheated steam from the saturated steam by exchanging heat between the combustion exhaust gas and the saturated steam through a superheater built into the waste heat boiler; heating the fluid by exchanging heat between the combustion exhaust gas and the fluid through a high-temperature heat exchanger built into the waste heat boiler; circulate the fluid between the high-temperature heat exchanger and the independent superheater; supplying the superheated steam to the independent superheater, exchanging heat between the superheated steam and the fluid, thereby heating the superheated steam; as well as The heated superheated steam is supplied to a steam turbine to generate electricity. The high-temperature heat exchanger has at least a plurality of high-temperature fluid heating pipes, which penetrate the side wall of the waste heat boiler and extend across the flow path of the combustion exhaust gas.

6. The method for power generation by burning waste according to claim 5, wherein: Heat exchange is performed between the fluid and the combustion exhaust gas by means of a heat-resistant panel installed on the inner surface of the waste heat boiler while the high-temperature fluid heating pipe is thermally insulated from the side wall of the waste heat boiler.

7. The method for power generation by burning waste according to claim 5, wherein: The high-temperature heat exchanger has a pressure wave soot blower that periodically imparts vibration to the high-temperature fluid heating pipe.

8. The waste combustion power generation method according to any one of claims 5 to 7, wherein: Triatomic molecules are supplied to the fluid, and the fluid containing the triatomic molecules is heated by the high-temperature heat exchanger.

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