JP2016041939A - Waste power generation system - Google Patents

Abstract

PROBLEM TO BE SOLVED: To improve exhaust heat recovery efficiency and power generation efficiency of a waste power generation system utilizing combustion heat of a waste incinerator and to achieve significant reduction in construction and running costs thereof.SOLUTION: A waste power generation system comprises: a first heat exchanger which recovers heat of a combustion chamber in an incinerator with a low boiling turbine operation working medium which can be evaporated as a heat medium; a first turbine power generation unit which generates electric power with an evaporated heat medium from the first heat exchanger as a working heat medium; a second heat exchanger which recovers heat of exhaust gas at a downstream side of a purification processing device with the low boiling turbine operation working medium which can be evaporated as the heat medium; and a second turbine power generation unit which generates the electric power with the evaporated heat medium from the second heat exchanger as the working heat medium.SELECTED DRAWING: Figure 1

Description

  The present invention relates to power generation using exhaust heat in municipal waste incineration plants, industrial waste treatment plants, and the like, and improves exhaust heat recovery efficiency without causing high-temperature corrosion in structures such as equipment and devices. The present invention relates to a waste power generation system that can improve power generation efficiency and reduce the size and cost of equipment and devices by increasing the power generation efficiency.

Generally, in power generation using exhaust heat that uses exhaust heat from incinerators such as municipal waste and industrial waste, boilers have a combined action of acid gases (such as HCl) in exhaust gas and corrosive components in dust. Equipment is corroded early. This corrosion includes low temperature corrosion in which exhaust gas is generated in a range of about 150 ° C. or lower and high temperature corrosion generated in a range of 320 ° C. or higher. In normal power generation using exhaust heat, the steam condition of a boiler device is about 270 ° C., The occurrence of the above corrosion has been avoided by setting it in the vicinity of 25 kg / cm ² . As a result, the exhaust heat recovery rate inevitably decreases and the power generation efficiency decreases, and the power generation efficiency is actually a low power generation efficiency of about 10 to 13%.

Of course, in order to improve the power generation efficiency, (a) a method of increasing the steam temperature to about 450 ° C. by using the material of the boiler component as a corrosion resistant material, (b) a method of neutralizing and removing acidic gas in the exhaust gas that is a corrosion-causing substance. Many measures have been taken, such as the adoption of a boiler structure that reduces the adhesion of dust and dust, the facilitation of replacement of the most corrosive steam superheater tubes, and the protection of steam superheater tubes with castable heat-resistant materials. It was.
However, each of the above countermeasures has a problem that it is difficult to fundamentally prevent corrosion, and power generation efficiency cannot be sufficiently increased, and plant construction costs and equipment maintenance costs increase.

On the other hand, a steam turbine power generation system by waste incineration and a gas turbine power generation system are combined as a measure to improve power generation efficiency using waste heat different from the above, and steam obtained from waste incineration exhaust heat is heated with exhaust gas after driving the gas turbine. However, a combined power generation system has been developed in which exhaust heat recovery efficiency and power generation efficiency are increased by introducing the superheated steam into a steam turbine to generate electric power (special opening and closing No. 5-0107).
However, in the combined power generation system of the steam turbine power generation and gas turbine power generation, both systems are closely integrated, and when the gas turbine power generation system is out of order, the steam turbine power generation with low power generation efficiency is performed. Independent operation or waste incinerator operation is forced to stop, making it easy to interfere with the original waste disposal work, and b) To cope with fluctuations in waste heat generation, it is necessary to always blow a part of the generated steam out of the system. As such, there are difficulties such as a decrease in heat recovery efficiency and power generation efficiency.

  Further, as an improvement of the above-described disadvantage of the combined power generation system, as shown in FIG. 2, the combined power generation system is configured by driving the compressor 34 and the generator 35 by the steam turbine 33 and utilizing the compressed gas from the compressor 34. The combined power generation system (Japanese Patent Laid-Open No. Hei 8-193505, etc.) in which the operation status of the gas turbine power generation system does not greatly affect the operation on the waste incineration system, as shown in FIG. A combined power generation system provided with a steam superheater 32b in the steam generator 32 of the waste incinerator 31 so as to obtain higher power generation efficiency while using high-temperature superheated steam at about 500 ° C. (Japanese Patent Laid-Open No. 2002-339709, etc.) Is provided.

  2 and 3, 31 is a waste incinerator, 32 is a steam generator, 32a is a waste heat boiler, 32b is a steam superheater, 33 and 40 are steam turbines, 34 is a compressor, 35 and 38 41 is a generator, 36 is a combustor, 37 is a gas turbine, 39 is a waste heat boiler, 42 and 43 are condensers, 44 and 45 are feed pumps, 46 is garbage, 47 is a gas such as air, 48 is Fuel gas, 49 is a header, 50 and 51 are chimneys, and 52 is a combustion furnace.

  The combined power generation system of FIG. 3 uses superheated steam at about 500 ° C., reheats low-pressure steam from the steam turbine 33 using exhaust heat of the gas turbine, and uses the reheated steam to steam steam 40. Therefore, the overall heat recovery efficiency can be increased and a power generation efficiency exceeding 35% can be achieved.

However, improving heat recovery efficiency inevitably increases the complexity of the plant system, which not only makes it difficult to operate and repair the plant, but also reduces the stability of the plant operation. become.
In addition, as the steam conditions are increased in temperature and pressure, a structural material with higher corrosion resistance is required, so that a significant increase in plant construction costs is unavoidable, and there is a problem that it cannot be reduced.

  Furthermore, due to the complexity of the plant system, even if an accident occurs in a part of the system, some accidents can easily spread to the entire system, resulting in the main business. There is a problem that the waste incineration process is delayed.

Japanese Patent Laid-Open No. 10-26016 JP-A-8-193505 JP 2002-339709 A

  In order to increase the heat recovery efficiency in order to increase the heat recovery efficiency, the present invention is based on the conventional waste power generation (exhaust heat power generation), particularly the combined power generation system related to the combination of the steam turbine and the gas turbine. It will be complicated and operation / repair will be difficult, the stability of plant operation will be relatively lowered, and b) high-temperature and high-pressure steam conditions will require structural materials with higher corrosion resistance. As a result, the construction cost of the plant will rise significantly, and it will not be possible to reduce it, and the plant system will become complicated, so some accidents will easily spread to the entire system and will be the main business. It is intended to solve problems such as stagnation in waste incineration, and uses a low boiling point heat medium that can be evaporated as a working medium for power generation turbines. By directly recovering heat from the combustion chamber combustion chamber and exhaust gas heat, it is possible to further reduce equipment and equipment manufacturing costs, operating and repair costs, and further improve exhaust heat recovery efficiency and power generation efficiency. To provide a waste power generation system.

  In the present invention, a combustion furnace using a heat medium (for example, heat medium oil, molten salt, etc.) that does not cause a phase change at a high temperature of about 300 ° C. is used instead of a low boiling point turbine operating heat medium that can be evaporated. (Waste incinerator) Heat recovery from the combustion chamber and use of a low-boiling point heat medium that can be evaporated instead of steam as the working medium for power generation turbines to manufacture equipment and devices by lowering the system pressure It is possible to provide a new waste power generation system capable of reducing costs and operating / repair costs, and improving exhaust heat recovery efficiency and power generation efficiency.

  The invention of claim 1 of the present application includes a first heat exchanger that recovers heat in a combustion chamber of a combustion furnace using an evaporable low boiling point turbine operating medium as a heat medium, and an evaporation heat medium from the first heat exchanger. A first turbine power generation unit that generates electricity using the heat generating medium as an operating heat medium, and a second heat exchanger that recovers heat of exhaust gas downstream of the purification treatment apparatus using the evaporable low boiling point turbine operating medium as a heat medium, And a second turbine power generation unit that generates power using the evaporation heat medium from the second heat exchanger as an operation heat medium.

  The first heat exchanger includes a heat exchange pipe provided in a combustion chamber of a combustion furnace and a heat exchange pipe provided in an exhaust gas passage downstream thereof, and heat using an evaporable low boiling point turbine operating medium as a heat medium. It is desirable to use an exchanger.

  Also, the heat exchange pipe provided in the combustion chamber of the combustion furnace of the first heat exchanger is a heat exchange pipe arranged in a spiral shape along the combustion chamber wall surface by a serial piping system or along the combustion chamber wall surface by a serial piping system. It is desirable that the heat exchange tubes be arranged vertically.

  As an example, it is desirable that the heat medium for operating the turbine of the first turbine power generation unit and the second turbine power generation unit is an evaporable low boiling point alternative chlorofluorocarbon (HFC-R245fa). Similarly, it is desirable to use a heat medium for operating the turbine for heat recovery of the first heat exchanger and the second heat exchanger, and a low-boiling alternative chlorofluorocarbon (HFC-R245fa) that can be evaporated.

  The combustion furnace to which the present invention is applied includes a stoker type incinerator, a fluidized bed type incinerator, a refuse melting treatment furnace, a refuse gasification treatment furnace, and the like.

In the present invention, a low boiling point turbine operating heat medium that can be evaporated is used as a heat recovery heat medium for the combustion chamber combustion chamber, so that a so-called intermediate heat exchanger is not required and the first heat exchange is performed. The design pressure values of the heat exchanger, the second heat exchanger, and the like are significantly reduced, and as a result, the manufacturing cost of both the heat exchangers and the like can be reduced.
In addition, high-pressure equipment such as a steam drum is completely unnecessary as in a conventional waste heat recovery boiler, and manufacturing costs and maintenance costs can be greatly reduced.
Furthermore, since a steam turbine is not used unlike conventional waste power generation, the initial cost and maintenance cost of the power generation facility can be reduced.

In the present invention, the heat transfer coefficient in the heat exchanger is greatly improved because the low boiling point heat medium that can be evaporated, which is the heat medium for operating the power generation system, is used as the heat exchange heat medium. In addition, it is possible to reduce the size of the heat exchanger and improve the heat recovery efficiency.
Furthermore, in the present invention, the exhaust heat recovery is performed also on the downstream side of the exhaust gas purification device, so that the heat recovery efficiency is increased by about 10% compared to the case of the conventional combined power generation system. The power generation efficiency is also improved by about 10%.

  In the present invention, by applying the inverter / converter power generation control system to the first and second power generation systems, even when the generation amount of steam is fluctuated due to a change in waste quality, Can follow economically.

  In particular, in the present invention, since the heat of the incinerator combustion chamber and the exhaust gas passage is directly recovered by the evaporable low boiling point heat medium that is the heat medium for operating the turbine, the facility cost can be further reduced and the heat recovery can be performed. Efficiency and power generation efficiency can be further improved.

It is composition explanatory drawing which shows an example of the waste power generation system which included this invention. It is a structure explanatory view of the conventional combined power generation system. It is a structure explanatory view of other conventional combined power generation system.

Hereinafter, embodiments of the present invention will be described with reference to the drawings.
FIG. 1 is a configuration explanatory view showing an outline of a waste power generation system including the present invention. The waste power generation system A includes a waste incinerator, a waste melting furnace, a waste combustion apparatus, etc. (hereinafter referred to as a waste heat source). A first heat exchanger 2 that recovers the heat of the combustion furnace 1, and a first intermediate heat exchanger that heats the operating heat medium L2 of the low-boiling-point first turbine by the recovered heat. 3, a first turbine power generation unit 4 that generates power using the heat medium L2, a second heat exchanger 5 that recovers the heat of exhaust gas downstream of the exhaust gas purification device 9, and a low boiling point due to the recovered heat Waste from the second intermediate heat exchanger 6 that heats the heat medium L2 for operating the second turbine and the second turbine power generation unit 7 that generates power using the heat medium L2 heated by the second intermediate heat exchanger 6 A power generation system is formed.
In the waste power generation system A including the present invention shown in FIG. 1, the first intermediate heat exchanger 3 for heating the heat medium L2 for operating the low-boiling point first turbine and the second low-boiling point second heat exchanger L2 are used. The second intermediate heat exchanger 6 that heats the turbine operating heat medium L2 is used. In the present invention, heat recovery is performed using the turbine operating heat medium L2 as a heat recovery heat medium. Therefore, the first intermediate heat exchanger 3 and the second intermediate heat exchanger 6 are not necessary and are omitted.
That is, from FIG. 1, the first intermediate heat exchanger 3 and the second intermediate heat exchanger 6 are deleted, and the turbine is used as a heat recovery medium from the first heat exchanger 2 and the second heat exchanger 5. A working heat medium L2 is an example of the present invention.

  The combustion furnace 1 serving as the exhaust heat source includes a stoker type waste incinerator, a fluidized bed type waste incinerator, a waste melting treatment furnace, a waste gasification treatment furnace, a waste combustion apparatus, and the like, but combustion using waste as a heat source Any furnace 1 is applicable to the present invention. In this embodiment, the stoker type incinerator is used as the combustion furnace 1.

  The stoker-type waste incinerator includes a waste supply hopper 1a, a waste supply pusher 1b, a stoker 1c, a combustion chamber 1d, an ash outlet 1f, and the like, and supplies primary combustion air a1 and secondary combustion air a2. Thus, the waste G is sequentially burned in the stoker 1c and the combustion chamber 1d. In addition, since the stoker-type waste incinerator itself is known, detailed description thereof is omitted here.

  The first heat exchanger 2 that recovers the heat in the combustion chamber 1d of the combustion furnace 1 includes a heat exchange pipe 2a for the combustion chamber arranged in the combustion chamber 1d, and heat for the exhaust gas passage arranged in the exhaust gas passage 1e. The heat exchanger L2 for turbine operation circulates and flows through the pump 12 through the pump 12.

  That is, the heat exchange pipe 2a for the combustion chamber is arranged in a spiral shape along the wall surface in the vicinity of the combustion chamber side wall of the combustion furnace 1 by using a single pipe or a plurality of parallel pipes in a so-called series piping system. The gap between the heat exchange tubes 2a is closed by fins (not shown). In addition, since the heat exchange pipe 2a is formed in a spiral shape by a serial piping system, the heat medium L2 for turbine operation flows through the pipe very smoothly.

  The heat exchange tubes 2a can be arranged vertically along the combustion chamber side wall. In this case, in order to ensure the fluidity of the heat medium L2 for operating the turbine, it is desirable to arrange it like a heat exchange pipe of a so-called single pipe boiler (through-flow boiler).

Instead of the turbine operating heat medium L2, it is also possible to use a high-temperature liquid heat medium L1 that does not cause a phase change even at a high temperature of about 300 ° C., as shown in FIG. However, in this case, naturally, the first intermediate heat exchanger 3 and the second intermediate heat exchanger 6 are necessary, and a liquid is desirable as the high-temperature heat medium L1. In the present embodiment, heat medium oil or molten salt is used as the heat medium L1.
Further, the high-temperature heat medium L1 may be any of mineral oil, synthetic, or inorganic, but it is desirable to use a heat medium oil from the viewpoint of deterioration characteristics and regeneration characteristics thereof. . Moreover, when raising use temperature, use of a synthetic | combination type | system | group or an inorganic type heat medium is suitable.

  The first intermediate heat exchanger 3 supplies heat recovered by the high temperature heat medium L1 to a low boiling point heat medium L2 that is a heat medium for operating the turbine 4a, and includes heat exchange pipes 3a and 3b. .

  The first turbine power generation unit 4 includes a turbine 4a, a generator 4b, a heat exchanger 4c, a cooling tower 4d, a receiver tank 4e, a pump 4f, a pump 4g, and the like, and after operating the turbine 4a. After being cooled and liquefied by the cooling tower 4d, the gas phase heat medium L2 is heated by the heat exchanger 4c and the first intermediate heat exchanger 3, and supplied to the turbine 4a as a heat medium for operation.

  As the heat medium L2 which is a heat heat medium for operating the turbine, an evaporable low boiling point heat medium, such as propane, pentane, toluene, chlorofluorocarbon alternative (HFC-R-245fa manufactured by Honeywell Co., Ltd.), or the like is used. In the present embodiment, for example, alternative chlorofluorocarbon (manufactured by Honeywell Co., Ltd., boiling point 15.3 ° C., vapor pressure 0.1 MPa at the boiling point is used as the heat medium L2 for operating the turbine.

The second heat exchanger 5 recovers heat in the exhaust gas discharged into the atmosphere, and is provided on the downstream side of the exhaust gas purification treatment device 9. That is, the heat medium L2 is circulated in the closed cycle by the pump 13, and the heat medium L2 that is the heat medium for operating the turbine is directly heated. In the case of using contact medium oil or the like as a heat medium for recovering the heat in the exhaust gas, the heat that is a heat medium for operating the turbine in the second intermediate heat exchanger 6 as shown in FIG. Medium L2 is heated.
Further, the configuration of the second turbine power generation unit 7 is exactly the same as the configuration of the first turbine power generation unit 4, and therefore the description thereof is omitted here.

Next, the operation of the waste power generation system shown in FIG. 1 will be described.
Referring to FIG. 1, when garbage G is burned in combustion furnace 1, a combustion gas of about 800 to 950 ° C. is generated in combustion chamber 1d. The heat of the combustion gas is absorbed by the heat medium L1 that flows through the heat exchange pipe 2a disposed in the combustion chamber 1d, whereby the heat medium L1 is heated to about 300 ° C. to the first intermediate heat exchanger 3. Inflow.
Further, the combustion exhaust gas in the combustion chamber 1d reaches a temperature of about 400 to 600 ° C. due to heat absorption by the heat medium L1, and flows out downstream through the exhaust gas passage 1e.

  The heat medium L1 further absorbs heat in the exhaust gas in the heat exchange pipe 2b provided in the exhaust gas passage 1e, and then flows into the first intermediate heat exchanger 3 to heat the heat medium L2 for operating the turbine. After the exchange, it is cooled to about 70 to 120 ° C. and returned to the heat exchange tube 2a.

  On the other hand, the combustion exhaust gas that has become about 350 to 400 ° C. due to heat absorption in the heat exchange pipe 2 b is cooled to 180 to 220 ° C. in the gas cooling chamber 8 and then flows into the gas purification treatment device (bag filter) 9. Then, after the purification process, it is discharged to the chimney 11 through the induction fan 10.

The exhaust gas having a temperature of 180 to 220 ° C. discharged from the purification treatment device 9 by the induction fan 10 is absorbed by the heat medium L1 in the second heat exchanger 5 and then released from the chimney to the atmosphere.
Further, the heat medium L1 heated to 160 to 200 ° C. by endothermic heat exchange with the heat medium L2 that is a heat medium for turbine operation in the second intermediate heat exchanger 6, and has a temperature of about 80 to 100 ° C. And returned to the second heat exchanger 5.

  The turbine operating heat medium L2 heated to 140 to 160 ° C. and vaporized in the second intermediate heat exchanger 6 is subjected to the same cycle as that of the first turbine power generation unit 4 in the turbine 7a and The generator 7b is operated.

In FIG. 1, the heat of the high-temperature heat medium L1 is transferred to the low-boiling-point heat medium L2 for turbine operation via the first intermediate heat exchanger 3, but in the present invention, 1 eliminates the first intermediate heat exchanger 3 shown in FIG. 1 and replaces the high-temperature heat medium L1 with a low-boiling-point heat medium L2 for turbine operation capable of evaporating without using the high-temperature heat medium L1. The heat recovery in the combustion chamber 1d is directly performed by the low boiling point heat medium L2.
Similarly, in the present invention, the low boiling point heat medium L2 of the evaporable second turbine power generation unit 7 is directly circulated to the heat exchange pipe of the second heat exchanger 5 instead of the high temperature heat medium L1. The heat recovery is performed by the turbine operating heat medium L2.

  The present invention can be applied not only to a waste combustion treatment furnace such as a waste incinerator but also to any combustion apparatus or combustion furnace in which high temperature corrosion may occur.

A Waste power generation system G Garbage (waste)
L1 High temperature heat medium (heat medium oil)
L2 Low boiling heat medium (alternative CFC)
1 Combustion furnace 1a Waste supply hopper 1b Waste supply pusher 1c Stoker 1d Combustion chamber 1e Exhaust gas passage 1f Ash outlet
a1 Primary combustion air
a2 Secondary combustion air 2 First heat exchanger 2a Heat exchange pipe 2b Heat exchange pipe 3 First intermediate heat exchanger 3a Heat exchange pipe 3b Heat exchange pipe 4 First turbine power generation unit 4a Turbine 4b Generator 4c Heat exchanger 4d Cooling tower 4e Receiver tank 4f Pump 4g Pump 5 Second heat exchanger 5a Heat exchange pipe 6 Second intermediate heat exchanger 6a Heat exchange pipe 6b Heat exchange pipe 7 Second turbine power generation unit 7a Turbine 7b Generator 7c Heat exchanger 7d Cooling tower 7e Receiver tank 7f Pump 7g Pump 8 Gas cooling chamber 9 Purification processing device 10 Induction fan 11 Chimney 12 Pump 13 Pump

Claims (6)

  A first heat exchanger that recovers heat from the combustion chamber of the combustion furnace using an evaporable low-boiling turbine operating medium as a heat medium, and power generation using the evaporating heat medium from the first heat exchanger as an operating heat medium. A first turbine power generation unit, a second heat exchanger for recovering heat of exhaust gas downstream of the purification treatment apparatus using a vaporizable low boiling point turbine operating medium as a heat medium, and the second heat exchanger A waste power generation system comprising: a second turbine power generation unit that generates power using the evaporative heat medium as an operation heat medium.   The first heat exchanger includes a heat exchange pipe provided in the combustion chamber of the combustion furnace and a heat exchange pipe provided in the exhaust gas passage downstream of the first heat exchanger, and heat exchange using a vaporizable low-boiling turbine operating medium as the heat medium. The waste power generation system according to claim 1, which is a container.   Heat exchange tubes provided in the combustion chamber of the combustion furnace are arranged in a spiral shape along the combustion chamber wall surface by a serial piping method or heat exchange tubes arranged vertically along the combustion chamber wall surface by a serial piping method The waste power generation system according to claim 2. Waste power generation system of claim 1 in which the first turbine generator unit and the second turbine generator units of a turbine working heat medium evaporation possible low-boiling CFC substitute (HFC-R245fa).   The waste power generation system according to claim 1, wherein the heat medium for heat recovery of the first heat exchanger and the second heat exchanger is a low-boiling-point alternative chlorofluorocarbon (HFC-R245fa) capable of evaporating.   The waste power generation system according to claim 1, wherein the combustion furnace is any one of a stoker type waste incinerator, a fluidized bed type waste incinerator, a waste melting treatment furnace, and a waste gasification treatment furnace.

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