JP2005118613A - System for drying and gasifying organic waste such as garbage or the like - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a system for drying and gasifying organic waste with a high waste content such as garbage or the like developed for the purpose of minimizing the use of external fuel energy. <P>SOLUTION: This system for drying and gasifying organic waste is constituted of an external heating dryer 1, a gasifying furnace 2, a predrying hopper 3, a vapor condensation type air preheater 4 or water heater and passages for garbage, steam, condensed water, air and a formed gas for connecting them. The garbage charged in the predrying hopper 3 is dried in a multistage fashion and supplied to the gasifying furnace 2 through a passage 5 provided with a flow channel cut-off valve 6 for batchwise operation. The sensible heat of the gasfied high temperature fuel gas is used as the heat source of the dryer 1. The generated steam in the dryer is guided to the heating gasket of the drying hopper 3 through a passage 8 to be used as the predrying heat source of the charged garbage. Further, the generated steam is also guided to the air preheater 4 through a passage 9 to become a preheating source of partial combustion air supplied to the gasifying furnace 2. A part of vapor condensed water can be injected in the gasifying furnace 2 or the gasified high temperature gas in order to regulate the temperature of the outlet gas of the gasifying furnace 2. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

The present invention generates high-temperature fuel gas by thermally decomposing organic waste such as food residues discharged from lunch centers, hotels, restaurants, supermarkets, food factories, etc. by thermal energy generated by partial combustion. This is a medium and small-sized distributed dry gasification system that evaporates water in organic waste such as input garbage by excess sensible heat recovery of high-temperature fuel gas, and efficiently performs self-drying using the obtained steam in cascade. is there.

In the 1930s and 1940s, small fixed-bed gasifiers using wood charcoal obtained by carbonizing thinned wood for use as fuel for small distributed power sources such as automobiles are used in Europe, where oil resources are scarce Although there was a time when technology was developed and put into practical use in Japan, fossil fuels such as oil became imported and procured at a low cost, and this technology has been forgotten for decades.

In recent years, as biomass has been reviewed as a renewable energy that is friendly to the global environment, wood-based organic waste with a relatively low moisture content, such as thinned wood, can be used in a small fixed-bed furnace based on the conventional fixed-bed type charcoal gasification technology. New technologies for direct pyrolysis gasification have been researched and developed mainly in Northern Europe and the United States.

However, with regard to organic waste such as food residues and garden tree pruning residues with high moisture content, little research has been done on the development of distributed direct pyrolysis gasifiers such as small fixed-bed furnaces. Without it, dry gasification has been considered difficult. In other words, according to the prior art, drying of garbage and the like does not recover the latent heat of vapor accompanying self-evaporation, but depends on external heat energy.
Nagao Fujio "Internal Combustion Engine Lecture Volume" Yokendo 1957 H.LaFontaine and FPZimmerman `` Gengassidan '' Biomass Energy Foundation Press 1820 Smith Rd., Golden, CO 80401 JP 2003-55566 A (P2003-55566A)

The direct pyrolysis gasification reaction of organic waste such as garbage in the fixed bed gasifier, which is a component of the above system, decomposes organic waste into volatile combustible gas at a relatively low temperature and at high temperature. It consists of a generator gas reaction, a water gas reaction, a shift reaction, etc. Among them, the generator gas reaction and the water gas reaction are endothermic reactions, so in order to maintain a predetermined temperature, heat from combustible gas partial combustion, etc. Supply is required.

Normally, the moisture content limit of self-combustion calculated from the calorific value of organic waste such as garbage is 80% or more, but the moisture content that enables stable gasification is empirically about 60% or less. There is a big gap. On the other hand, since the average moisture content of organic waste such as municipal waste is around 80%, a larger amount of heat supply is required to replenish the latent heat of water evaporation. In other words, it means that it is extremely difficult to stably maintain the temperature required for the gasification reaction even if organic waste such as municipal waste with high water content is left as it is. Therefore, it is necessary to adjust the water content of organic waste such as municipal waste by some method so that the moisture content is within an appropriate range before being supplied to the fixed bed gasifier as a gasification raw material.

The present invention provides a system for solving the above-mentioned problems without depending on supplementation of external energy such as fuel. When gasifying organic waste such as garbage with a high water content, the sensible heat of the gasified high-temperature fuel gas produced in the gasifier and the latent heat of vaporized steam accompanying the drying of the garbage itself are input garbage. It is a system that can be reused for evaporative drying.

The first invention is an indirect external heating dryer for evaporating moisture in organic waste such as garbage by sensible heat of high-temperature fuel gas obtained when the garbage is gasified,
An indirect external heating predrying storage hopper connected to the upper part of the indirect external heating dryer and supplying garbage from above;
Connected to the lower part of the indirect external heating dryer, and by the dry garbage containing the appropriate amount of moisture necessary for pyrolysis gasification and the air required for partial combustion to self-procure heat energy for pyrolysis A fixed-bed gasifier for gasifying garbage;
Means for adjusting the gasifier outlet temperature of the fuel gas generated by the gasifier;
A steam condensing type air preheater for preheating and supplying air for partially burning garbage in the gasification furnace, or a steam condensing water heater for generating and supplying hot water for general use,
Steam obtained by evaporating the moisture in the garbage of the indirect external heating dryer is introduced into the external heating jacket of the pre-drying storage hopper, and the moisture of the garbage being stored is evaporated in the pre-drying storage hopper. An organic waste drying gasification system for garbage such as garbage, wherein the obtained water vapor is condensed by the vapor condensation type air preheater or the vapor condensation type hot water heater.

According to the first invention, the temperature of the gasification reaction part of the gasification furnace can be maintained sufficiently high to satisfy the conditions for realizing stable gasification, and the surplus heat can be effectively used. That is, the sensible heat of the gasification hot gas at the gasification furnace outlet obtained as a result of gasification is sufficiently transferred to the garbage in the indirect external heating dryer to increase the evaporation of moisture in the garbage and to remove excess moisture. In addition to recovering the sensible heat of gasified hot gas, not only to supply to the gasification furnace, but also newly condensing latent heat of water vapor evaporated from moisture in the garbage in the indirect external heating dryer Making it possible to effectively use as a pre-drying heat source for high moisture content garbage put into the drying hopper, and further, condensing latent heat of water vapor evaporated from moisture in the high moisture content garbage in the predrying hopper For example, preheating the gasification air as a heat source for the preheater, or using it effectively as general hot water.

According to a second aspect of the present invention, there is provided a gasification furnace outlet temperature adjusting means for the fuel gas generated by the fixed bed type gasification furnace in the first aspect, wherein the indirect external heating pre-drying storage hopper and the vapor condensation type air are used. Injecting a part of the condensed water from the preheater or the steam condensing water heater into at least one of the upper storage tank part of the gasification furnace or the gasification fuel gas supply passage at the gasification furnace outlet, and / or This is achieved by controlling the amount of gasification furnace injection air.

According to the second invention, the reaction of the gasifier gasification section is appropriately controlled and the operation of the gasifier can be stabilized.

A third invention is an indirect type external heating dryer for evaporating moisture in organic waste such as garbage by gasification of the garbage by high-temperature fuel gas sensible heat;
An indirect external heating predrying storage hopper connected to the upper part of the indirect external heating dryer and supplying garbage from above;
Connected to the lower part of the indirect external heating dryer, and by the dry garbage containing the appropriate amount of moisture necessary for pyrolysis gasification and the air required for partial combustion to self-procure heat energy for pyrolysis A fixed-bed gasifier for gasifying garbage;
A flow path shut-off valve for opening and closing a passage for supplying garbage from the indirect external heating dryer to the gasification furnace disposed below the indirect type external heating dryer;
Means for adjusting the gasifier outlet temperature of the fuel gas generated by the gasifier;
A steam condensing type air preheater for preheating and supplying air for partially burning garbage in the gasifier, or a steam condensing water heater for generating hot water for general use,
Steam obtained by evaporating the moisture in the garbage of the indirect external heating dryer is introduced into the external heating jacket of the pre-drying storage hopper, and the moisture of the garbage being stored is evaporated in the pre-drying storage hopper. An organic waste drying gasification system for garbage such as garbage, wherein the obtained water vapor is condensed by the vapor condensation type air preheater or the vapor condensation type hot water heater.

According to the third invention, the fixed bed gasification furnace that should stably gasify the garbage and the dryer that generates and supplies the garbage with an appropriate moisture content, which is the condition, are separated in an apparatus, and each batch Enabled driving operation. That is, when the gasification furnace is started up, an appropriate amount and a suitable moisture content range within which the gasification is most stably performed are filled in the upper storage tank of the gasification furnace. And the operation conditions of the indirect external heating dryer and the indirect external heating pre-drying storage hopper in the previous stage so that the next batch can supply the same amount of dry garbage in the appropriate moisture content range to the gasifier. And set the input garbage condition. Thus, it is possible to facilitate the operation required for the small distributed system.

According to a fourth aspect of the invention, there is provided a gasification furnace outlet temperature adjusting means for the fuel gas generated by the fixed bed type gasification furnace according to the third aspect of the invention, the indirect external heating pre-drying storage hopper and the vapor condensation type air. Injecting a part of the condensed waste water from the preheater or the steam condensing water heater into at least one of the upper storage tank section of the gasifier or the gasified fuel gas supply passage at the outlet of the gasifier, and / or This is achieved by controlling the amount of gasification furnace injection air.

According to the fourth invention, the reaction of the gasifier gasification section is appropriately controlled even during batch operation, and the gasifier operation can be stabilized.

According to the present invention described above, as a new treatment system for organic waste such as municipal waste such as food residue and garden tree pruning residue with high water content, a medium- and small-sized fixed-bed gasifier type that has a great deal of technical experience This makes it possible to provide a new energy-saving distributed garbage drying gasification system that is simple in structure and easy to operate. As a result, it becomes possible to treat the source of garbage at lunch centers, hotels, restaurants, supermarkets, food factories, etc., and to reduce the discharge to the outside. In this system, it is possible to minimize the wasteful dissipation of the energy inherent in garbage as latent heat of moisture evaporation into the atmosphere, so the net energy recovery rate as gasified fuel gas is increased accordingly. Can do. The recovered gasified fuel gas can be opened up as a new biomass energy resource that is friendly to the global environment.

Next, embodiments of the present invention will be described with reference to the drawings. 1 and 2 are views showing an embodiment of an organic waste dry gasification system such as garbage according to the present invention.

A first embodiment of the present invention will be described with reference to FIG.
As shown in FIG. 1, the organic waste drying gasification system such as garbage of this embodiment includes an indirect external heating dryer 1 as a main component, a fixed bed gasification furnace 2 connected to the subsequent stage, A preliminary drying hopper 3 connected to the preceding stage, and a steam condensation type air preheater 4 or a steam condensation type water heater attached to the preliminary drying hopper 3 are provided. The pre-drying hopper 3 introduces and heats the evaporated water vapor in the indirect external heating dryer 1 into the external heating jacket of the pre-drying hopper, and pre-drys and stores the high-moisture-content garbage input from outside the system. Is. The indirect-type external heating / drying machine 1 stores the dried raw garbage by externally heating and drying the pre-dried raw garbage using the sensible heat of the gasified hot gas as a heat source. The gasification furnace 2 combusts part or all of the volatile components in the dry garbage and completely gasifies nonvolatile carbon and the like using the thermal energy as a main heat source. The upper part of the gasification furnace 2 serves as a temporary storage place for unreacted dry garbage. In the downdraft type fixed bed gasification furnace, combustion air is introduced into this part. The vapor condensing air preheater 4 preheats combustion air using the vapor evaporated from the predrying hopper 3 as a heat source. The steam condensing water heater generates general hot water using the evaporated water vapor of the preliminary drying hopper 3 as a heat source.

Each of the above system components is connected by a passage for appropriately moving a predetermined amount of garbage, water vapor and condensed water, air, product gas, or the like by gravity, buoyancy, or a fan pump at a predetermined time. In other words, the garbage is supplied from the indirect external heating / drying device 1 through the passage 5 to the storage tank at the upper part of the gasification furnace 2. A flow path shutoff valve 6 is provided in the passage 5. Evaporated water vapor accompanying garbage drying is supplied to the heating jacket of the preliminary drying hopper 3 from the indirect external heating dryer 1 through the passage 8. The evaporated water vapor accompanying the preliminary drying is supplied from the preliminary drying hopper 3 through the passage 9 to the steam condensation type air preheater 4 or the steam condensation type water heater. The preheated air is supplied to the gasification furnace 2 through the passage 10. Condensed water is automatically discharged out of the system by the siphon tube 11, and a part of the condensed water can be injected into the storage tank at the upper part of the gasification furnace 2 or the gasification fuel gas supply passage 13. The gasified fuel gas thus generated is introduced into the indirect external heating / drying device 1 through the passage 13, and the temperature thereof is lowered. Then, the gasified fuel gas is supplied to the fuel gas demand destination outside the system through the passage 14 by the fuel gas suction fan 15. .

According to the embodiment having the above-described configuration, the loss of heat energy associated with gasification of organic waste such as garbage with high water content can be extremely reduced. In other words, the sensible heat of gasified fuel is effectively recovered for drying garbage, and the loss of latent heat of vaporization due to the mixing of water vapor into the fuel gas and the loss of latent heat of vaporization due to the release of evaporated moisture into the atmosphere due to drying And can be minimized. In addition, one batch of dry garbage within the appropriate moisture content range where gasification is most stably performed is filled into the upper storage tank of the gasification furnace 2, and the same moisture content is applied to the next batch. Indirect type external heating dryer 1 and indirect type external heating pre-drying storage hopper 3 are charged with appropriate amount and appropriate garbage so that dry garbage in the rate range can be supplied to the gasifier, and then indirect type external heating dryer Close the flow path shut-off valve 6 provided in the passage 5 from 1 to the gasification furnace 2 and start the gasification furnace to perform so-called batch operation that separates dry garbage gasification from the dry garbage supply function. Can be implemented.

A second embodiment of the present invention will be described with reference to FIG.
As shown in FIG. 2, the gasification furnace outlet temperature of the fuel gas generated by the gasification furnace 2 is changed to the predrying storage hopper 3 and / or the condensate of the air preheater 4 or the steam condensation type water heater is changed to the gasification furnace 2. When adjusting by injecting into the gas storage fuel gas supply passage 13 at the upper storage tank portion of the gasification furnace or at the gasification furnace outlet, the temperature of the gasification furnace outlet fuel gas is detected by the thermometer 16, and the temperature controller 17 Thus, the adjustment valves 18 and 19 provided in the vicinity of each injection point of the condensed water in the passage 12 can be adjusted at a preset constant sensitivity ratio, or alternatively, the gasification furnace injection air amount can be adjusted by the adjustment valve 20 This is different from the first embodiment in that it can be adjusted with the first embodiment. Other configurations of the present embodiment are the same as those of the first embodiment shown in FIG.

Among the injection points of the condensed water 12, the injection into the upper storage tank of the gasification furnace 2 is effective for direct control of the gasification reaction, whereas the gasification fuel gas supply passage The injection into 13 is effective by controlling the water evaporation performance of the indirect external heating dryer 1, and the combined operation of the garbage drying gasification system against variations in the properties of the garbage. The applicable range can be increased.

Schematic diagram showing a first embodiment of a system for drying and gasifying organic waste such as garbage according to the present invention The schematic diagram which shows 2nd Embodiment of organic waste dry gasification systems, such as garbage by this invention

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Indirect type external heating dryer 2 Gasification furnace 3 Pre-drying hopper 4 Evaporated water condensation type air preheater (or steam condensation type water heater)
5 Dry Garbage Passage 6 Channel Shut-off Valve 7 Preliminary Dry Garbage Passage 8 Indirect External Heating Dryer Evaporating Steam Passage 9 Predrying Hopper Evaporating Steam Passage 10 Preheating Air Passage 11 Condensed Water Siphon Pipe 12 Condensed Water Passage 13 Gasified Fuel Gas supply passage 14 Gasified fuel gas supply passage 15 Fuel gas suction fan 16 Gasifier outlet fuel gas thermometer 17 Temperature controller 18 Condensate injection adjustment valve 19 Condensate injection adjustment valve 20 Preheated air amount adjustment valve

Claims (4)

An indirect external heating dryer for evaporating moisture in organic waste such as garbage by evaporating sensible heat of high-temperature fuel gas obtained by gasifying the garbage;
An indirect external heating pre-drying storage hopper connected to the upper part of the indirect external heating dryer and receiving freshly introduced garbage from above;
Connected to the lower part of the indirect external heating dryer, and by the dry garbage containing the appropriate amount of moisture necessary for pyrolysis gasification and the air required for partial combustion to self-procure heat energy for pyrolysis A fixed-bed gasifier for gasifying garbage;
Means for adjusting the gasifier outlet temperature of the fuel gas generated by the gasifier;
The indirect external heating drying apparatus, comprising: a steam condensing type air preheater for preheating and supplying air for partial combustion of garbage in the gasification furnace, or a steam condensing type water heater for supplying hot water for general use Steam obtained by evaporating the moisture in the kitchen garbage is introduced into the external heating jacket of the pre-dry storage hopper, the moisture of the garbage being stored is evaporated in the pre-dry storage hopper, and the resulting water vapor is Organic waste drying gasification system such as garbage, which is condensed by the steam condensing type air preheater or the steam condensing water heater. The adjustment means of the gasifier outlet temperature of the fuel gas generated by the fixed bed type gasifier is the indirect type externally heated pre-drying storage hopper and the condensed water of the steam condensed air preheater or the steam condensed water heater. This is achieved by injecting a part of the gasification fuel into at least one of the upper storage tank section of the gasification furnace and the gasification fuel gas supply passage at the gasification furnace outlet and / or controlling the gasification furnace injection air amount. The organic waste drying gasification system for garbage such as garbage according to claim 1. An indirect external heating dryer for evaporating moisture in organic waste such as garbage by evaporating sensible heat of high-temperature fuel gas obtained by gasifying the garbage;
Connected to the upper part of the indirect type external heating dryer, connected to the indirect type external heating pre-drying storage hopper and the lower part of the indirect type external heating dryer for receiving freshly introduced garbage from above, for pyrolysis gasification A fixed-bed gasifier for gasifying the garbage by dry garbage containing the necessary amount of moisture and air required for partial combustion to self-procure heat energy for thermal decomposition;
A flow-off valve for opening and closing a passage for supplying garbage from the indirect external heating dryer to the fixed-bed gasifier disposed below and a gas of fuel gas generated by the gasifier Means for adjusting the furnace outlet temperature,
The indirect external heating drying apparatus comprising: a steam condensing type air preheater for preheating and supplying air for partially burning garbage in the gasification furnace; or a steam condensing type water heater for supplying hot water for general use Steam obtained by evaporating the moisture in the kitchen waste is introduced into the external heating jacket of the pre-drying storage hopper, the water in the garbage being stored is evaporated in the pre-drying storage hopper, and the resulting water vapor is Organic waste drying gasification system such as garbage, which is condensed by the steam condensing type air preheater or the steam condensing water heater. The adjustment means of the gasifier outlet temperature of the fuel gas generated by the fixed bed type gasifier is the indirect type externally heated pre-drying storage hopper and the condensed water of the steam condensed air preheater or the steam condensed water heater. This is achieved by injecting a part of the gasification fuel into at least one of the upper storage tank section of the gasification furnace and the gasification fuel gas supply passage at the gasification furnace outlet and / or controlling the gasification furnace injection air amount. The organic waste dry gasification system for garbage such as garbage according to claim 3.

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