JPH10317918A - Energy recovery method from combustible - Google Patents

Abstract

PROBLEM TO BE SOLVED: To generate high electric power by low temperature steam by burning combustible in a combustion furnace, recovering heat generated at combustion by a heat recovery part, and leading a medium holding heat generated in the heat recovery part to a heat cycle using fluid mixed with two sorts or more components having different boiling points so as to generate electric power. SOLUTION: Wastes are burned up in an incinerator 1, exhaust gas generated at the time is led to a waste heat recovery device 2 to heat-exchange between the gas and a medium flowing in the waste heat recovery device 2. The medium changed to hot water or steam by in heat exchange in the waste heat recovery device 2 is returned to the waste heat recovery device 2 through a steam generator 10. In this case, for heat recovery of hot water or steam generated in the waste heat recovery device 2, a heat cycle Hc using multi-component mixture containing a low boiling point component as working fluid is utilized. When multi-component mixture containing a low boiling component such as a mixture of ammonia and water, steam can be generated at about 70 deg.C, while is led to a turbine to drive a generator.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for recovering energy from combustibles, and more particularly to a method for combusting combustibles such as waste and coal, and recovering heat generated during the combustion to generate electric power. It relates to a method for recovering energy.

[0002]

2. Description of the Related Art Conventionally, various kinds of waste such as municipal waste, waste plastic, sewage sludge, and industrial waste have been reduced in volume by incineration or have been dumped untreated.

[0003] In recent years, with the recognition of the finiteness of fossil fuels and the demand for resource recycling of waste, there has been a growing interest in effectively utilizing the energy of waste. Discarding untreated waste has made it difficult to secure a place for dumping and is no longer acceptable for environmental protection. Therefore, a waste heat boiler is installed in the incinerator that incinerates waste, heat is recovered from the high-temperature exhaust gas rising in the incinerator by the waste heat boiler, and is converted into high-temperature steam. Energy recovery systems from wastes that generate electricity by operating turbines have been put to practical use. Recently, in order to obtain as much electric power as possible in this energy recovery system, 400 ° C.
Attempts have been made to increase the steam temperature to near 500 ° C.

[0004]

However, a comparatively small scale (in the case of municipal waste incineration equipment, the amount of waste disposal is about 100 tons / day; in the case of RDF incineration equipment, the disposal amount is 50 tons / day)
Power generation using high-temperature steam is not suitable from the viewpoint of economic efficiency and operation management.

Conventionally, in such a small-scale facility, high-temperature exhaust gas discharged from an incinerator is cooled by a gas cooling facility (cooling by removing heat from the exhaust gas as latent heat when spraying water and evaporating). The heat held by the exhaust gas was dumped in the atmosphere. On the other hand, even small-scale waste incineration equipment consumes electric power, so a power generation equipment that can supply electric power within the equipment is necessary. From such a background, there has been a demand for a power generation facility that is excellent in economics and operation and maintenance without increasing the temperature of the steam as compared with the related art, and that can obtain as much power as possible.

The present invention has been made in view of the above circumstances, and has as its object to provide a method for recovering energy from combustible materials suitable for combustion equipment such as small-scale waste incineration equipment.

[0007]

SUMMARY OF THE INVENTION In order to achieve the above-mentioned object, the present invention provides a method for burning combustible materials such as wastes in a combustion furnace, and recovering heat generated during the combustion in a heat recovery section. The medium holding the heat generated in the section is led to a heat cycle using a fluid in which two or more components having different boiling points are mixed to generate power.

[0008]

Embodiments of the present invention will be described below in detail with reference to the drawings. FIG. 1 is a schematic diagram showing the entire configuration of an apparatus used in the method for recovering energy from combustibles according to the present invention. In the embodiment shown in FIG. 1, a description will be given by taking waste as an example of combustibles.

The waste used in the present invention includes municipal waste, solidified fuel (RDF), slurry fuel (SW)
M), biomass waste, plastic waste (including FR)
P), automobile waste (shredder dust, waste tires), household waste, special waste (medical waste, etc.), sewage sludge, human waste, highly concentrated waste liquid, industrial sludge, etc. Waste and low-grade coal can be used, but they can also be combined appropriately.

Here, solidified fuel, RDF (Rufuse-Deri
Ved Fuel) is made by crushing and sorting municipal solid waste, adding quicklime and compression molding. Slurry fuel, SWM (Solid
(Water Mixture) is a municipal solid waste that is crushed and turned into a water slurry, and then turned into oil by hydrothermal decomposition under high pressure. FRP is a fiber reinforced plastic, and low-grade coal is low-coalization lignite, lignite, peat, or scum like coal produced during coal preparation.

The above-mentioned waste is put into an incinerator 1 and incinerated. Exhaust gas generated at the time of incineration is guided to a waste heat recovery device 2 installed in the incinerator 1, and exchanges heat with a medium (water) flowing in the waste heat recovery device 2. The exhaust gas discharged from the waste heat recovery device 2 is discharged to the atmosphere via a dust collection facility and a chimney. The medium flowing in the waste heat recovery device 2 may be air.

On the other hand, the medium which has undergone heat exchange in the waste heat recovery unit 2 to become hot water or steam returns to the waste heat recovery unit 2 as hot water or water via the steam generator 10. Waste heat recovery unit 2
A portion of the hot water or steam generated by heat exchange in the inside is withdrawn from upstream or downstream of the steam generator 10 and is provided for use in the site (shown by A or B).

The present invention provides a heat cycle in which a multi-component mixture containing a low-boiling component is used as a working fluid for heat recovery of hot water or steam generated in the waste heat recovery device 2 (hereinafter referred to as a multi-component mixed fluid heat cycle). ) Is intended to improve the thermal efficiency of the entire system. When a mixture of ammonia and water is used as a multi-component mixture containing low-boiling components, for example, an ammonia concentration of about 80 wt.
%, And a pressure of 25 kg / cm ² abs, steam can be generated at about 70 ° C. As described above, according to the multi-component mixed fluid heat cycle including the low-boiling components, steam that can be sufficiently used for power generation at a high pressure at a low temperature is guided to the turbine,
In addition to being able to generate electric power by the generator, heat can be efficiently recovered in the cycle by further utilizing the characteristics of the mixed fluid, so that high-efficiency power generation can be performed. In the condensation regeneration system provided in the heat cycle, in order to use the heat input in the heat cycle as efficiently as possible, heat exchange is performed between working fluids, and concentration of the working fluid is changed. .

As shown in FIG. 2, the multi-component mixed fluid heat cycle Hc includes a steam generator 10, a turbine 11 for driving a generator 19, a pump 13, a heat exchanger 15A such as a regenerator, and the like.
15B and a condenser 16. A portion 21 surrounded by a broken line is a condensation regeneration system.

In the above-described configuration of the multi-component mixed fluid heat cycle Hc, first, the multi-component mixed fluid enters the steam generator 10 and holds the heat of the heat source, that is, the hot water or steam generated by the waste heat recovery unit 2. After being converted into a mixed steam by the generated heat, it expands in the turbine 11 and turns the generator 19 to perform work. The heat of the turbine exhaust is used to heat a part of the multi-component mixed fluid condensed by the condenser 16 in the two heat exchangers 15A and 15B, and the temperature of the turbine exhaust decreases. The multi-component mixed fluid that has exited the condenser 16 and the heat exchanger 15B is divided into a stream flowing into the steam generator 10 and a stream flowing into the heat exchanger 15A. The fluid that has flowed into the heat exchanger 15A returns to the steam generator 10 after passing through the heat exchanger 15A.

The multi-component mixed fluid heat cycle Hc uses a multi-component mixture of two or more components having different boiling points as a working fluid. Also, at least one of the components,
The substance has a lower boiling point than water. The working fluid has the following attributes that are effective as working fluids for power generation by the turbine generator. a. Low boiling point temperature. b. The boiling point and the dew point have different temperatures (non-isothermal evaporation and non-isothermal condensation). c. Changing the concentration changes the condensation pressure.

Since the working fluid has the above characteristics, there are the following advantages that can contribute to the improvement of the efficiency of the cycle at various points constituting the heat cycle. 1) Since a working fluid having a low boiling point is supplied to a steam generator, steam can be generated even at a low temperature, and a heat source can be used up to a low temperature. 2) Since the evaporator evaporates while the temperature rises, the temperature difference from the heat source can be reduced as compared with the conventional steam cycle, and heat recovery from the heat source can be performed effectively. 3) On the turbine exhaust side, the temperature decreases and condenses while decreasing. Therefore, if a working fluid whose temperature is lower than that of the turbine exhaust side returned to the condenser is supplied to the heat exchanger provided on the turbine exhaust side, the turbine exhaust side working fluid Can recover the heat possessed by As a result, the amount of heat released from the condenser to the outside of the cycle decreases, so that the output of the turbine generator increases. 4) Depending on the temperature condition of the heat source and the power generation scale, the exhaust pressure can be reduced by reducing the working fluid on the turbine exhaust side and then condensing it. As a result, the heat drop in the turbine increases, and the output of the turbine generator increases.

In the multi-component mixed fluid heat cycle, the number of steam generators, heat exchangers, pumps, condensers, turbines, and generators may exceed the number shown in FIG. Some devices may not be used. Also, a separator may be added. The concentration of the multicomponent fluid is
In FIG. 2, it is fixed without changing, but may be changed in a cycle.

FIG. 3 is a view showing a second embodiment of the thermal cycle. As shown in FIG. 3, the multi-component mixed fluid heat cycle Hc includes a steam generator 10 and a turbine 1 that drives a generator.
1, a pump 13, a condenser 16, and a heat exchanger 20. A portion 21 surrounded by a broken line is a condensation regeneration system. In the configuration of the multi-component mixed fluid heat cycle Hc described above, first, the multi-component mixed fluid enters the steam generator 10 and is heated by the heat of the heat source, that is, the heat held by the hot water or steam generated by the waste heat recovery unit 2. After having become the mixed steam, it expands in the turbine 11 and turns the generator 19 to perform work. The heat of the turbine exhaust is used to heat a part of the multi-component mixed fluid condensed by the condenser 16 in the heat exchanger 20, and the temperature of the turbine exhaust decreases. The multi-component mixed fluid leaving the condenser 16 and the heat exchanger 20 returns to the steam generator 10.

FIG. 4 is a diagram showing a second embodiment of the present invention. In the present embodiment, hot water or steam generated in the waste heat recovery unit 2 provided in the incinerator 1 is used in the plant (indicated by C). And the exhaust gas that has exited the waste heat recovery unit 2 is
It is guided to the waste heat recovery unit 5 at the subsequent stage, and exchanges heat with a medium (water) flowing in the waste heat recovery unit 5. The exhaust gas discharged from the waste heat recovery device 5 is released to the atmosphere via a dust collection facility or the like.

On the other hand, the medium that has undergone heat exchange in the waste heat recovery unit 5 to become hot water or steam returns to the waste heat recovery unit 5 as hot water or water via the steam generator 10. Steam generator 1
The configuration of the zero- and multi-component mixed fluid thermal cycle Hc is shown in FIG.
Has the same configuration as the example shown in FIG. 1 and the operation principle is also the same, and therefore, the description is omitted.

In the embodiment shown in FIGS. 1 to 4, an example in which the present invention is applied to an incineration facility for incinerating waste has been described. However, the present invention is also suitably applied to a combustion facility for burning fuel such as coal. used. When the combustion equipment has a waste heat boiler, the waste heat boiler may be used as the heat recovery unit.

[0023]

As described above, according to the present invention, the following effects can be obtained. 1) High-output power can be generated by low-temperature steam without generating high-temperature steam as in the related art. 2) Since the hot water or low-pressure steam originally required for combustion equipment such as waste incineration equipment is used as a medium in the heat recovery unit, the operation management of the equipment is easy for the combustion equipment operation manager. 3) If the medium in the heat recovery unit is hot water, the operation and maintenance of the equipment can be further facilitated. 4) A safe medium such as a mixture of water and ammonia can be used as a medium in the heat cycle. In addition, a medium such as a water / ammonia mixture can generate high output power in a heat cycle.

[Brief description of the drawings]

FIG. 1 is a schematic diagram showing the entire configuration of a first embodiment of an apparatus used for a method of recovering energy from combustibles according to the present invention.

FIG. 2 is a view showing a first embodiment of a heat cycle used in the method for recovering energy from combustibles according to the present invention, and showing a multi-component mixed fluid heat cycle.

FIG. 3 is a view showing a second embodiment of the thermal cycle.

FIG. 4 is a schematic view showing the entire configuration of a second embodiment of the apparatus used in the method for recovering energy from combustibles according to the present invention.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Incinerator 2, 5 Waste heat recovery device 10 Steam generator 11 Turbine 13 Pump 15A, 15B Heat exchanger 16 Condenser 19 Generator 20 Heat exchanger 21 Condensation regeneration system Hc Multicomponent mixed fluid heat cycle

──────────────────────────────────────────────────続 き Continued on the front page (51) Int.Cl. ⁶ Identification code FIF23G 5/46 B09B 3/00 303H (72) Inventor Tatsuo Nakamura 11-1 Haneda Asahimachi, Ota-ku, Tokyo Inside Ebara Corporation

Claims (6)

[Claims] Claims 1. Combustible materials such as wastes are burned in a combustion furnace.
The heat generated during combustion is recovered in the heat recovery unit, and the medium holding the heat generated in the heat recovery unit is guided to a heat cycle using a fluid that is a mixture of two or more components with different boiling points to generate power. A method for recovering energy from combustible materials, characterized in that: 2. The method for recovering energy from combustibles according to claim 1, wherein the medium holding heat is hot water, steam or air. 3. The method for recovering energy from combustibles according to claim 1, wherein the heat cycle is a heat cycle using a fluid in which two or more components having different boiling points are mixed. 4. The energy recovery from a combustible according to claim 3, wherein at least one of the two or more components having different boiling points has a boiling point lower than that of water. Method. 5. The heat recovery unit according to claim 1, wherein the heat recovery unit includes a waste heat recovery unit provided in the combustion furnace.
A method for recovering energy from combustibles as described in the above. 6. The method for recovering energy from combustibles according to claim 1, wherein the heat recovery section comprises a waste heat recovery device provided downstream of the combustion furnace.