JP2001520360A - Waste combustion power generation method and apparatus - Google Patents

Abstract

(57) [Summary] Electric power is generated with high efficiency from high-temperature and high-pressure steam generated by utilizing the heat of flue gas generated when various kinds of waste are burned. The waste is burned in an incinerator or a gasification and melting furnace (11) to generate flue gas. The generated combustion exhaust gas is introduced into the heat exchanger (12), and heats a gas such as air by heat exchange. The superheated steam is heated by a superheated steam heater (14) by using the heated gas as a heat source, and the heated superheated steam is supplied to a steam turbine (15) connected to a generator to generate power.

Description

DETAILED DESCRIPTION OF THE INVENTION

TECHNICAL FIELD [0001] The present invention relates to a method and an apparatus for generating electricity by burning waste, and more particularly to high-temperature molten salt corrosion utilizing heat of combustion exhaust gas after burning various kinds of waste (waste). The present invention relates to a waste-combustion power generation method and apparatus for obtaining high-temperature and high-pressure steam while avoiding troubles caused by a heat exchanger, thereby improving power generation efficiency.

Technical Background Waste (waste) treatment in the 21st century is expected to change drastically, changing from a simple incineration treatment to a circulation type system that recovers energy with zero dioxin emissions and high efficiency. . First of all, since garbage is collected and sorted, recycling technology is required depending on the type of waste. For general waste, gasification melting combustion technology that can simultaneously achieve dioxin countermeasures and ash melting with its own combustion heat will be the mainstream, and for plastic mixed garbage, chemical recycling technology that converts to chemical raw materials will be the mainstream. Can be It is considered that high-efficiency waste power generation requires a technology with a power generation efficiency of 30% or more.

[0003] As a thermal recycling method that uses thermal energy generated by burning refuse for power generation, a method is generally used in which the heat of refuse combustion is recovered by steam in a waste heat boiler, and power is generated by a steam turbine and a generator. FIG. 4 shows an example of such a conventional power generation system using refuse incineration. As shown in FIG. 4, the waste is burned in an incinerator or a gasification and melting furnace 11, and the combustion exhaust gas is recovered in a waste heat boiler 13 to generate superheated steam. Then, the superheated steam is supplied to the steam turbine 15, and power is generated by a generator directly connected to the steam turbine. The generated power is consumed in the incineration plant and sold to a power company. The combustion exhaust gas that has passed through the waste heat boiler 13 is supplied to a preheater 16 such as an economizer, a bag filter 17.
Etc., and is released to the atmosphere from the chimney as a low-temperature clean gas.

[0004] In such steam turbine power generation, the power generation efficiency greatly depends on the steam temperature of superheated steam supplied to the steam turbine. The higher the steam temperature is, the higher the efficiency is. However, in a conventional practical waste incineration power generation system, the steam temperature is limited to about 400 ° C. due to the following reasons.
%.

The reason why the steam temperature cannot be practically raised to about 400 ° C. or higher is that there are problems of corrosion by corrosive gas components such as hydrogen chloride generated by combustion of refuse and high-temperature molten salt corrosion. In the case of a waste heat boiler, even at a pressure of about 100 kg / cm ² , 310 ° C.
Corrosion can be avoided even when a metal heat transfer tube is used because saturated steam of relatively low temperature flows. However, in the case of superheated steam, since the steam temperature is as high as 400 ° C. or more, the surface of the metal heat transfer tube is corroded and damaged by corrosive components such as high-temperature molten salt.

[0006] The mechanism of the corrosion is complicated, and various factors overlap to cause a reaction. The greatest point of corrosion is whether or not the heat transfer tube is exposed to the environment of the molten salt of NaCl and KCl, rather than the HCl concentration. In this environment, the salts melt and adhere to the heat transfer tubes, which accelerates the corrosion of the heat transfer tubes at an accelerated rate.

[0007] Estimated from our many years of experience and corrosion tests using municipal solid waste incinerators,
FIG. 5 shows the form of corrosion on the surface of the heat transfer tube using the combustion exhaust gas temperature (horizontal axis) and the surface temperature of the heat transfer tube (vertical axis) as parameters. As shown in FIG. 5, there are four types of corrosion: “a severe corrosion area”, “a corrosion progress area”, “a corrosion reduction area”, and “a non-corrosion area” determined by the combustion exhaust gas temperature and the heat transfer tube surface temperature. Superheated steam temperature 400
In the case of 0 ° C., the surface temperature of the heat transfer tube is about 430 ° C., which is about 30 ° C. higher than the steam temperature, and FIG. . This means that in a waste heat boiler of an incinerator for municipal solid waste, the temperature of exhaust gas entering a boiler bank (a portion where evaporating water pipes are densely packed) is raised to 600 ° C.
This is consistent with the fact that salts adhere to the heat transfer tube and block the exhaust gas flow path.
That is, it is considered that the boundary between the molten state and the solidified state of the salt is around 600 ° C. This is consistent with the solidification temperature of the composite salt. That is, the melting points of the salts are 800 ° C. for NaCl and 776 ° C. for KCl. However, since the salts become complex salts after melting, the solidification temperature is as low as 550 to 650 ° C. Difference). This boundary temperature is 600
In some cases, the temperature may be lower than ° C. This is thought to be due to the high salt concentration. Also, as shown in FIG. 5, even when the exhaust gas temperature is 500 ° C. or more and 600 ° C. or less, when the heat transfer tube surface temperature becomes about 430 ° C. or more, it enters the “corrosion reduction region”, and the corrosion slightly proceeds from the molten salt corrosion. . Therefore, when used in this region, the material selection of the superheater tube is important. Since the surface temperature of the heat transfer tube is usually about 30 ° C. higher than the superheated steam temperature, the allowable corrosion limit of the superheated steam temperature (the upper limit of the steam temperature in a non-corrosive region) may be considered to be about 400 ° C. However, when the superheated steam temperature is 400 ° C., the steam pressure is suppressed to about 3.9 MPa due to the problem of the drain attack of the turbine.
The power generation efficiency can only be increased to about 20%.

Accordingly, in order to obtain a superheated steam of 400 ° C. or more while avoiding the “corrosion progressing region”, it is necessary to install a superheated steam pipe in a temperature range of 500 to 600 ° C. of the combustion exhaust gas from FIG. Must. However, in this case, the combustion exhaust gas (500 to 600 ° C.)
) And superheated steam (400 ° C. or more) become smaller, so that it is necessary to increase the heat transfer surface of the heat exchanger in order to perform desired heat transfer, resulting in inefficiency and an increase in equipment size. There was a problem.

On the other hand, practical use of high-efficiency power generation by material development has been attempted, in which a metal material that resists corrosion is developed to increase power generation efficiency using a high steam temperature without corrosion of a heat transfer tube. However, material development is technically and economically difficult, and there is no practical prospect yet. In addition, an RDF power generation system for dechlorination and desulfurization by adding lime or the like to refuse and converting it into a solid fuel has been attempted. However, in this method, even if the HCl component can be reduced, the molten salt corrosion is almost equal to the conventional one. Therefore,
When attempting to obtain superheated steam at a temperature of 500 ° C. with exhaust gas at a temperature of 800 ° C. or more, the surface temperature of the heat transfer tube becomes about 530 ° C. As shown in FIG. 5, the heat transfer tube is exposed to a “severely corroded area”. become.

[0010] Furthermore, super garbage power generation has been attempted in which power is generated by a gas turbine and steam in a refuse waste heat boiler is reheated by waste heat of the gas turbine to increase the power generation efficiency of a steam turbine / generator. However, this method has a problem in that it requires a large amount of other high-quality fuels besides wastes, and is economical. Still further, a fuel reheating method for increasing the power generation efficiency of a steam turbine by reheating and reheating the steam of the waste heat boiler separately with fuel has been studied. However, this method also has a problem in economy because a large amount of other high-quality fuel is used in addition to waste.

DISCLOSURE OF THE INVENTION The present invention has been made in view of the above circumstances, and causes a problem that a heat exchanger corrodes due to corrosive components such as high-temperature molten salt contained in combustion exhaust gas of waste. It is another object of the present invention to provide a waste combustion power generation method and apparatus for generating power by burning waste and increasing power generation efficiency by increasing superheated steam temperature.

In the waste combustion power generation method of the present invention, the waste is burned to generate high-temperature flue gas, the flue gas is introduced into a heat exchanger, and the gas is heated by heat exchange, and the heated gas is heated. With the use of the heated gas as a heat source, the temperature of the superheated steam is raised, and the heated superheated steam is supplied to a steam turbine connected to a generator to generate power.

Further, the waste combustion power generation device of the present invention performs heat exchange between a combustor that burns waste to generate high-temperature combustion exhaust gas and a combustion exhaust gas and gas discharged from the combustor. A heat exchanger for heating a gas, a heater for exchanging heat between the heated gas and the superheated steam to raise the temperature of the superheated steam, And a steam turbine connected to the machine for generating electric power.

According to the present invention, the flue gas obtained by combustion of waste is guided to a heat exchanger, and a gas such as air flowing in a heat transfer tube of the heat exchanger is heated. The heated gas is used as a heat source. The superheated steam obtained by a waste heat boiler or the like is heated, and the heated superheated steam is supplied to a steam turbine connected to a generator to generate power. In other words, instead of directly introducing the flue gas into the waste heat boiler to raise the temperature of the superheated steam, the flue gas is guided to a heat exchanger, and a fluid such as air is heated. The temperature was raised. Since heat exchangers that heat air and other gases with flue gas do not need to be pressurized as in the case of steam, use materials specified in regulations such as boiler structure standards and technical standards for power generation thermal power equipment. No need. Therefore, a ceramic material can be used for the heat exchanger, and in this case, the problem of molten salt corrosion of the heat transfer tube hardly occurs. In addition, even when a heat exchanger made of heat-resistant cast steel or metal is used, the heat transfer tube exposed to the combustion exhaust gas can be used in the environment of the corrosion reduction region shown in FIG. It is unlikely to occur. In particular, heat-resistant cast steel was known to be resistant to corrosion, but it could not be used for a superheated steam pipe due to regulations in the conventional method. In the present invention, since the heat-resistant cast steel is used not as a steam tube but as a heat transfer tube between exhaust gas and a gas such as air, it can be used in the present invention.

According to the present invention described above, the high-temperature flue gas comes into contact with the pipe of the high-temperature heat exchanger and heats a gas such as air flowing through the pipe. When the surface temperature of the heat transfer tube is 700 ° C. or higher, corrosive components contained in the combustion exhaust gas have a low high-temperature molten salt corrosion action on the heat transfer tube. If the pipe surface temperature of the heat transfer tube is 700 ° C. or higher, the corrosion enters the “corrosion reduction area” of FIG. 5 and the pipe corrosion is reduced. Therefore, in a high-temperature heat exchanger, even if a metal heat transfer tube is used, corrosion is reduced, and a gas such as air flowing through the tube is heated to, for example, 700 ° C.
It can be heated to a high temperature. Next, the superheated steam of about 400 ° C. obtained in the waste heat boiler is reheated with the gas such as air of about 700 ° C.
Superheated steam of about 0 ° C. can be easily generated. Since the heat medium used for reheating the superheated steam is not a flue gas but a high-temperature gas such as air, the problem of high-temperature molten salt corrosion does not occur here. Furthermore, since air is a heating source instead of flue gas, the heat transfer coefficient does not decrease due to dust adhering to the pipe surface, and the superheated steam heater can be made compact. Then, by supplying the superheated steam having a high temperature of 500 ° C. or more to the steam turbine connected to the generator, high-efficiency power generation with a power generation efficiency of 30% or more can be achieved without a problem of corrosion.

FIG. 6 shows the difference in the corrosion rate of the heat transfer pipe due to the combustion exhaust gas of the present invention in which the superheated steam is directly heated with the exhaust gas and the conventional technology in which the superheated steam is heated indirectly with the exhaust gas. In the conventional method of heating the superheated steam by the flue gas directly (shown by curve A), the pipe surface temperature is shifted to the low-temperature steam side instead of the high-temperature exhaust gas side because the heat transfer coefficient of the film on the steam side is large. , Are exposed to the "severely corroded area" of FIG. On the other hand, the method of the present invention (
In curve B), the flue gas heats not the steam but the gas such as air. In the case of air, since the film heat transfer coefficient on the air side is smaller than that in the case of steam, the pipe surface temperature is shifted to the exhaust gas side. For this reason, the "corrosion reduction area" of FIG.
Enter. According to such an indirect heating method of superheated steam, molten salt corrosion can be avoided, so that existing metal materials can sufficiently cope with the problem. Here, a difference in tube surface temperature due to a difference in film heat transfer coefficient of the fluid will be described. The tube surface temperature Tw is calculated by the following equation. Tw = T− {hio / (hio + ho)} × (T−t) where T: exhaust gas temperature t: heat receiving fluid temperature ho: film heat transfer coefficient of exhaust gas hio: film heat transfer coefficient of heat receiving fluid

1) When the heat receiving side is superheated steam, T = 1200 ° C., t = 500 ° C., ho @ 100 kcal / m ² h ° C., hio @ 200
Assuming 0 kcal / m ² h ° C. (it becomes a very high value in the case of superheated steam), Tw = 1200− {2000 / (2000 + 100)} × (1200−500) = 533 ° C. Exposed. 2) When the heat receiving side is air, T = 1200 ° C., t = 500 ° C., ho @ 100 kcal / m ² h ° C., hio @ 200
If kcal / m ² h ° C. (a low value in the case of a gas such as air), Tw = 1200− {200 / (200 + 100)} × (1200−500) = 733 ° C., so that severe corrosion can be avoided. Since low-pressure air can be used as the heat exchange medium, ceramic materials can also be used. Whether the material is metal or ceramics or the like is determined according to use conditions. For example, when the tube surface temperature is 800 ° C. or higher, the strength decreases with metal,
Ceramics and heat-resistant cast steel are desirable.

BEST MODE FOR CARRYING OUT THE INVENTION The objects, features and advantages of the present invention will be apparent from the accompanying drawings and the following description which illustrate preferred embodiments of the present invention. FIG. 1 shows a basic flow of the waste combustion power generation system of the present invention. As shown in FIG. 1, in an incinerator or a gasification and melting furnace 11, waste (waste) is burned to generate combustion exhaust gas. The combustion exhaust gas is passed through a high-temperature heat exchanger 12 using a heat-resistant metal or ceramics, and heats a gas such as air, preferably to about 700 ° C. The combustion exhaust gas that has passed through the high-temperature heat exchanger 12 is supplied to a waste heat boiler
Produces steam from the supplied water, and further heats them to produce a steam pressure of 100
Generate superheated steam of about kg / cm ² and steam temperature of about 400 ° C. The superheated steam is a gas such as air at about 700 ° C. heated by the high-temperature heat exchanger 12 and the superheated steam heater 1.
The heat is exchanged in Step 4 and heated to about 500 ° C. This superheated steam is supplied to a steam turbine 15 connected to a generator to generate power. The flue gas discharged from the waste heat boiler 13 preheats a fluid such as air by an air preheater 16 to increase the temperature of gas such as air entering the high-temperature heat exchanger 12. The exhaust gas heats the feedwater with an economizer, and the heated feedwater is supplied to the waste heat boiler 13. The combustion exhaust gas that has passed through the air preheater 16 and has become low temperature is collected by a bag filter 17 and the like, and is discharged as a clean gas from a chimney.

As described above, the high-temperature heat exchanger 12 is installed in the high-temperature exhaust gas line exiting from the incinerator or the gasification-melting furnace 11, and the gas such as air is heated to 500 ° C. or more, preferably 700 ° C.
The superheated steam of about 400 ° C. is heated to about 500 ° C. by the superheated steam heater 14 using the heated air. The superheated steam heated by the superheated steam heater 14 is supplied to a steam turbine 15 connected to a generator to generate power. Gases such as air exchanged by the superheated steam heater 14 are used as combustion air for the incinerator or the gasification and melting furnace 11.

In the case of the incinerator 11, since the temperature of the exhaust gas is about 850 ° C., and the temperature difference between the exhaust gas and the air in the high-temperature heat exchanger 12 is small, the heat transfer area is large. In the case of the furnace 11, since the temperature of the combustion exhaust gas is 1200 ° C. or higher, the temperature difference is large, and the heat transfer area of the high-temperature heat exchanger 12 can be small. As a gas such as air, an inert gas such as air or nitrogen is preferable.

FIG. 2 shows a structural example of a bayonet type heat exchanger which is an example of the heat exchanger. The bayonet-type heat exchanger includes a large number of double-tube heat exchange units 31. FIG. 2 shows only one heat exchange section having a double tube structure. The heat exchange section 31 having a double-pipe structure includes an outer cylinder 32 having a substantially cylindrical container shape with one end opened and the other end closed, and a cylindrical inner cylinder 33 having both ends opened. The high-temperature combustion exhaust gas contacts the outer surface of the outer cylinder 32. Gas such as low-temperature air flows in from one end of the inner cylinder 33, flows into the annular space between the outer cylinder 32 and the inner cylinder 33 from the opening at the other end, and flows out from the opening at one end of the outer cylinder 32. During this time,
A gas such as air is heated by exchanging heat with the combustion exhaust gas. Since the bayonet heat exchanger includes the heat exchange section 31 having a double pipe structure, heat exchange between the combustion exhaust gas and the gas is performed in two stages. That is, heat exchange is performed between the gas flowing in the inner cylinder 33 and the gas flowing in the space between the outer cylinder 32 and the inner cylinder 33, the combustion exhaust gas outside the outer cylinder 32, This is a two-stage heat exchange consisting of heat exchange performed with a gas flowing through the space between the cylinder 33. Since the low-temperature gas is heated by the first-stage heat exchange, the pipe surface temperature of the second-stage heat exchange in contact with the exhaust gas is increased, thereby avoiding a “severely corrosive region”. In addition, since the material has a high temperature and therefore has a large amount of thermal expansion, fixing both ends of the heat transfer tube makes it difficult to take measures against thermal expansion. Therefore, a cantilever of this type has a simpler structure and is more advantageous.

The heat-resistant cast steel used in the bayonet heat exchanger is preferably JIS SCH material.
As the metal, a heat-resistant alloy having a high content of nickel (Ni), cobalt (Co), and chromium (Cr) is desirable. In the case of ceramics, SiC (silicon carbide) is preferred. When a raw piece of SiC, alumina, and silicon nitride was exposed to high-temperature exhaust gas of about 1350 ° C. in a gasification melting furnace for one month, alumina and silicon nitride were completely melted, but SiC had a thickness of 10 mm to 5 mm. It was reduced in thickness, but it remained in its original form. Further, the wall thickness was largely reduced in the flow direction of the exhaust gas, and the wall thickness was small where the flow was weak. Regarding the relationship between the exhaust gas temperature and the thickness reduction of SiC, if the surface temperature of the SiC is 1000 ° C. or less, almost no wall thickness reduction occurs in the flow direction of the exhaust gas. From the above, using SiC as a heat exchanger material and setting the SiC surface temperature to 1000 ° C.
In the following case, the service life can be greatly extended. Of course, the material used is selected according to the conditions of use, but basically any material may be used.

Note that the heat exchanger is not limited to the bayonet type, but it is preferable that the heat exchanger be capable of heating the low-temperature fluid with the high-temperature fluid in order to increase the temperature of the heat transfer surface in contact with the exhaust gas. Further, the heat exchanger may be arranged in two or more stages, and may have different structures for medium temperature and high temperature. For example, the air of about 250 ° C. for medium temperature is heated to about 500 ° C.
When the temperature of the air at 00 ° C. is raised to about 700 ° C., the bayonet type may be used for the medium temperature and another general heat exchanger may be used for the high temperature. The reason is about 500
This is because if the air temperature is 0 ° C., the surface temperature of the heat transfer tube becomes 700 ° C. or more and enters the corrosion reduction region shown in FIG. Conversely, the high temperature type may be a bayonet type using ceramics.

FIG. 3 is a flowchart of a waste combustion power generation method and apparatus according to another embodiment of the present invention. In the embodiment of FIG. 3, as shown in FIG. 3, an example in which the present invention is applied to a gasification and melting system in which waste is gasified and burned using a fluidized bed gasification furnace and a swirling melting furnace is shown. First, the waste is charged into the fluidized-bed gasification furnace 21 and heated to 500 to 600 ° C. in an oxygen-deficient state in which the amount of oxygen is lower than the theoretical amount of oxygen necessary for burning the waste, and gasified. According to the fluidized bed gasifier 21, since the fluidized bed temperature is low and the atmosphere is a reducing atmosphere, metals such as iron, copper, and aluminum can be recovered in an unoxidized state. The pyrolysis gas including char, tar and the like generated in the fluidized bed gasification furnace 21 is sent to the swirling melting furnace 22 and burns at a high temperature of 1350 ° C. or more without auxiliary fuel. The combustion temperature may be 1200-1500C. In the swirling melting furnace 22, gas combustion is mainly performed, so that combustion at a low air ratio of about 1.3 is possible.
The amount of exhaust gas from the plant can be reduced. And because the gas burns at 1200 ° C or higher,
Complete decomposition of dioxin is possible. Then, in the swirling melting furnace 22, the slag can be efficiently separated by the centrifugal force effect by using the swirling flow, harmful substances such as heavy metals are sealed in the slag, and cooled to cool the heavy metals into a glassy solid. Can be contained.

The waste heat boiler 24 that generates superheated steam is connected to the swirling melting furnace 22, and the high-temperature heat exchanger 23 is provided in a radiant heat transfer section of the waste heat boiler 24. High temperature heat exchanger 2
Reference numeral 3 denotes a heat exchanger using heat-resistant cast steel, heat-resistant metal, SiC (ceramics), or the like as a pipe material.
Heat to 0-800 ° C, preferably about 700 ° C. At this time, the temperature of the combustion exhaust gas is preferably 1000 to 1300 ° C., preferably about 1200 ° C., which is convenient for avoiding the adhesion of ash, and the temperature difference between the air flowing through the high-temperature heat exchanger 23 and the exhaust gas can be made large. The heat exchange area of the vessel 23 can be reduced. For this reason, the heat exchanger can have a compact structure. Since low-pressure air of ² kg / cm ² or less, preferably about 0.05 kg / cm ² flows in the pipe of the heat exchanger 23, there is no need to have a pressure-resistant structure, and a ceramic pipe may be used. It may be made of cast steel. The installation location of the high-temperature heat exchanger 23 is not limited to the radiant heat transfer section of the waste heat boiler, but may be between the melting furnace 22 and the waste heat boiler 24. For example, a duct may be provided downstream of the melting furnace 22 and the high-temperature heat exchanger 23 may be installed in the duct.

The air heated to 500 to 800 ° C., preferably about 700 ° C., exchanges heat with the superheated steam heater 25 to heat superheated steam at about 400 ° C. to 400 to 600 ° C., preferably about 500 ° C. . The air whose temperature has been lowered by the heat exchange is supplied to the swirling melting furnace 22.
Is supplied as combustion air. At this time, the temperature of the combustion air is 350 to 550 ° C.
Since the temperature is preferably as high as about 450 ° C., high-temperature combustion can be efficiently performed in the swirling melting furnace. The superheated steam heated to a temperature of 400 to 600 ° C., preferably about 500 ° C. by the superheated steam heater 25 is supplied to a steam turbine 26 directly connected to a generator at a pressure of about 100 kg / cm ² to generate power. This achieves a power generation end efficiency of about 30 to 32% while avoiding the problem of high-temperature molten salt corrosion. Note that the power generation end efficiency increases as the superheated steam temperature increases. Since the temperature of the superheated steam can be raised to 500 ° C. or more by the superheated steam heater 25, the system that generates power by burning waste can generate power with high efficiency.

The superheated steam pipe 30 of the waste heat boiler 24 exchanges heat with air in the high-temperature heat exchanger 23,
The superheated steam of about 400 ° C. is generated by using the combustion exhaust gas whose temperature has been reduced to about 600 ° C. by the heat absorption by the radiant heat transfer section of the waste heat boiler 24. As shown in FIG. 5, the problem of high-temperature molten salt corrosion does not occur when the temperature of the combustion exhaust gas is lowered to about 600 ° C. The outlet temperature of the combustion exhaust gas from the waste heat boiler 24 is about 350 ° C., and the exhaust gas is supplied to the economizer 27 where the waste heat boiler 2
Preheat water supply to 4. The exhaust gas discharged from the economizer 27 is supplied to the air preheater 2
8 and the air preheater 28 supplies air to the high-temperature heat exchanger 23 with 150-3.
Preheat to 00 ° C. Then, the combustion exhaust gas discharged from the air preheater 28 and lowered in temperature to about 160 ° C. is removed through a dust remover 29 such as a bag filter and discharged as a clean gas from a chimney.

The waste gasification / melting combustion system can operate at a low air ratio, so that the boiler efficiency is high, the power consumption of the ventilation equipment is greatly reduced, and the power for melting the ash is unnecessary, so the power transmission end efficiency Is greatly improved. High-efficiency thermal recycling is not high-efficiency power generation but high-efficiency power transmission. In addition, the gasification and melting system can be operated without using other auxiliary fuels, and is reasonable and economical. Table 1 shows a comparative example of the power transmitting end efficiency in each system.

[0029]

[Table 1]

In Table 1, 100ata × 540 ° C, 40ata × 400 ° C, and 100ata × 500 ° C are the pressure and temperature of the superheated steam in each system. Table 1 shows that the gasification and melting system shown in Fig. 3 generates high temperature and high pressure (100ata x 500 ° C) superheated steam to generate electricity (gasification and melting-II), but the power transmission efficiency is 28.1%. The highest is shown. The combination of the incinerator and the ash melting furnace has the highest power generation efficiency by adopting the method of obtaining high-temperature superheated steam of the present invention to generate power. However, since the amount of power consumed by the ash melting furnace is large, the power transmission efficiency is 26. It drops to 1%. It is also shown that the conventional system (Gasification-I), which generates electricity using heated superheated steam (40ata x 400 ° C) heated directly by the combustion exhaust gas, has the lowest power generation efficiency and transmission efficiency. It is.

According to the present invention, a pipe such as heat-resistant cast steel, a heat-resistant metal, or ceramics is disposed in a high-temperature combustion exhaust gas to heat a gas such as air, and exchange heat with the high-temperature gas such as air to cause overheating. The steam is reheated. Thereby, the superheated steam temperature of about 500 ° C. or more can be obtained from the combustion exhaust gas of the waste containing corrosive gas while avoiding high-temperature molten salt corrosion, and the power generation end efficiency of 30% or more can be obtained. It is. While the preferred embodiment of the invention has been illustrated and described, various changes and modifications can be made without departing from the scope of the invention. INDUSTRIAL APPLICABILITY The present invention is applied to a waste treatment facility that generates electricity with high efficiency from high-temperature and high-pressure steam generated by the heat of exhaust gas generated when various types of waste are burned.

[Brief description of the drawings]

FIG. 1 is a flowchart showing one embodiment of a waste combustion power generation method and apparatus according to the present invention.

FIG. 2 is a sectional view of a bayonet heat exchanger.

FIG. 3 is a flowchart showing another embodiment of the waste combustion power generation method and apparatus of the present invention.

FIG. 4 is a diagram showing a conventional waste combustion power generation system.

FIG. 5 is a diagram showing a relationship between corrosion by combustion exhaust gas temperature (horizontal axis) and pipe surface temperature (vertical axis).

FIG. 6 is a diagram showing a relationship between a heat transfer tube surface temperature and a corrosion rate.

[Procedural Amendment] Submission of translation of Article 34 Amendment of the Patent Cooperation Treaty

[Submission date] April 14, 2000 (2000.4.14)

[Procedure amendment 1]

[Document name to be amended] Statement

[Correction target item name] Claims

[Correction method] Change

[Correction contents]

[Claims]

──────────────────────────────────────────────────続 き Continued on the front page F term (reference) 3G081 BA02 BC13 BC30 3K023 QA06 QA12 QA14 QB01 QB03 QC08 QC13 3K065 AA11 AB02 AB03 AC01 BA05 BA06 BA08 JA05 JA15 JA18

Claims (17)

[Claims] 1. A waste gas is burned to generate high-temperature flue gas, the flue gas is introduced into a heat exchanger, a gas is heated by heat exchange, and the superheated steam is used as a heat source by using the heated gas as a heat source. A waste combustion power generation method characterized by raising the temperature of the fuel, supplying the heated superheated steam to a steam turbine connected to a generator, and generating power. 2. The method according to claim 1, wherein the heat exchanger tubes of the heat exchanger that come into contact with the combustion exhaust gas are made of heat-resistant cast steel or ceramics. 3. The waste combustion power generation method according to claim 1, wherein the heat transfer tube of the heat exchanger that comes into contact with the combustion exhaust gas is formed of a heat-resistant metal. 4. The method according to claim 1, wherein the heat exchanger is a bayonet heat exchanger. 5. The waste combustion power generation method according to claim 1, wherein the surface temperature of the heat transfer tubes of the heat exchanger is maintained at 700 ° C. or higher. 6. The waste combustion power generation method according to claim 1, wherein the superheated steam is generated by guiding combustion exhaust gas to a waste heat boiler. 7. The waste combustion power generation method according to claim 1, wherein the heat exchange between the gas and the superheated steam is performed by a superheated steam heater. 8. The waste combustion according to claim 1, wherein the gas is air, and the air is preheated by the combustion exhaust gas in an air preheater before being supplied to the heat exchanger. Power generation method. 9. The heating of the superheated steam is performed by a superheated steam heater, and the air discharged from the superheated steam heater is introduced as combustion air into an incinerator or a gasification and melting furnace. The waste combustion power generation method according to claim 8. 10. A combustor for burning waste and generating high-temperature flue gas,
A heat exchanger for performing heat exchange between the combustion exhaust gas and the gas discharged from the combustor and heating the gas, and performing a heat exchange between the heated gas and the superheated steam to form the superheated steam. A waste combustion power generation device comprising: a heater for raising the temperature; and a steam turbine to which the heated superheated steam is supplied and which is connected to a generator to generate electric power. 11. The waste combustion power generation device according to claim 10, wherein the heat transfer tube of the heat exchanger that comes into contact with the combustion exhaust gas is made of heat-resistant cast steel or ceramics. 12. The waste combustion power generation device according to claim 10, wherein the heat transfer tube of the heat exchanger that comes into contact with the combustion exhaust gas is formed of a heat-resistant metal. 13. The waste combustion power generation device according to claim 10, wherein the heat exchanger is a bayonet type heat exchanger. 14. The waste combustion power generation device according to claim 10, wherein the surface temperature of the heat transfer tubes of the heat exchanger is maintained at 700 ° C. or higher. 15. The waste combustion power generation device according to claim 10, further comprising a waste heat boiler that supplies the combustion exhaust gas and generates the superheated steam. 16. The waste combustion according to claim 10, wherein the gas is air, and the air is preheated by the combustion exhaust gas in an air preheater before being supplied to the heat exchanger. Power generator. 17. The waste combustion power generation device according to claim 16, wherein the air discharged from the heater is introduced as combustion air into an incinerator or a gasification and melting furnace.