JP2010077260A - Combustible gas-forming apparatus for gasifying waste and process for producing combustible gas - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a combustible gas-forming apparatus which can more enhance the calorific value of a gas formed by the thermal decomposition of waste than before. <P>SOLUTION: The combustible gas-forming apparatus includes a fluidized bed gasifier 3 for thermally decomposing waste to form a thermally decomposed gas, a plasma furnace 4 for thermally decomposing tar in the thermally decomposed gas formed in the fluidized bed gasifier 3 and unreacted residues to form a reformed gas, a heat exchanger 5 for generating water vapor to be supplied to the fluidized bed gasifier 3 and a drying preheating oven 2 by utilizing the heat of the reformed gas formed in the plasma furnace 4, and a scrubber 7 arranged to the rear of a bag filter 6 to condensate the water vapor present in the reformed gas to discharge the condensed water. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to a combustible gas generating apparatus and a combustible gas production method for pyrolyzing and gasifying waste such as municipal waste and industrial waste.

Aiming to realize a low-carbon society as a measure against global warming. Conventionally, in waste incineration facilities such as municipal waste, waste heat generated by incineration is effective by driving a turbine with steam from a waste heat boiler and generating a part of the power in the facility. It was used. Here, when considering further energy recovery from waste such as municipal waste, rather than energy recovery (power generation) using a waste heat boiler-steam turbine, the waste is pyrolyzed and gasified, and the gas is used. The energy recovery rate is higher when power is generated by a gas engine or a gas turbine. On the other hand, in order to operate a gas engine with combustible gas generated from waste, it is necessary to increase the calorific value (unit: kcal / Nm ³ ) of the combustible gas.

Here, the gas engine is likely to knock when the heat amount of the fuel gas is low, and is difficult to apply to the gas engine even when there is a load fluctuation in the fuel gas. For this reason, when the calorie | heat amount of fuel gas is low, it will be necessary to mix with city gas which is a fossil fuel, and to stabilize calorie | heat amount. For this reason, in order to use gasified gas for a general-purpose gas engine, generally 2000 kcal / Nm ³ or more is required as the calorie of the gas. In addition, if the heat quantity of the fuel gas is low in a gas turbine, it may be misfired in the combustion chamber, so it is necessary to lengthen the combustion chamber, but it is difficult to change the combustion chamber length for aircraft conversion engines, etc. Selection is also greatly limited.

  Conventionally, as a technique for thermally decomposing waste such as municipal waste and industrial waste to gasify, there is a technique described in Patent Document 1, for example. In the gasification technique described in Patent Document 1, a steam plasma torch is provided in a product gas reforming chamber or a gasification furnace, and gasification of organic substances is promoted by plasma from the steam plasma torch.

JP 2003-147373 A

  However, as in the technique described in Patent Document 1, it is not possible to sufficiently increase the calorific value of gas generated from waste such as municipal waste simply by promoting gasification of waste using water vapor plasma. Can not.

  This invention is made | formed in view of the said situation, The objective is providing the combustible gas production | generation apparatus which can raise the emitted-heat amount of the gas produced | generated by thermally decomposing waste compared with the past. It is.

Means and effects for solving the problems

  In order to solve the above problems, the present invention provides a gasification furnace that thermally decomposes input waste to generate pyrolysis gas, and at least an unreacted residue in the pyrolysis gas generated in the gasification furnace. A reforming furnace that generates reformed gas by pyrolysis, a heat exchanger that generates steam to be supplied into the gasification furnace using heat of the reformed gas generated in the reforming furnace, There is provided a combustible gas generation device comprising: a water vapor separation unit that condenses and discharges water vapor contained in the reformed gas.

  According to this configuration, the steam is used for the thermal decomposition of the waste in the gasification furnace, and then the steam contained in the reformed gas is condensed, separated from the reformed gas, and discharged, thereby combustible in the reformed gas. The ratio of the components can be increased, and as a result, the calorific value of the reformed gas can be increased as compared with the conventional case. Further, since the steam for use in the thermal decomposition of the waste is generated using the heat of the reformed gas, the energy recovery rate can be increased.

  In the present invention, it is preferable that the water vapor separation means is a gas scrubber that further lowers the temperature of the reformed gas that has passed through the heat exchanger and has fallen to 60 ° C. or less.

  According to this configuration, the reformed gas is washed and the water vapor (water) contained in the reformed gas is condensed and separated and removed. Thereby, the emitted-heat amount of reformed gas can be raised more. By setting the temperature of the reformed gas to 60 ° C. or less, the amount of water vapor (moisture) contained in the reformed gas is about 20% or less, and the amount of heat of the reformed gas can be increased. It can be suitably used for a turbine.

  Furthermore, in the present invention, separation means for separating unreacted residue and gas in the pyrolysis gas generated in the gasification furnace, and unreacted that supplies the unreacted residue separated by the separation means to the reforming furnace And a residue supply means.

  According to this configuration, most of the workpieces supplied to the reforming furnace become unreacted residues. Therefore, most of the heat applied in the reforming furnace can be used for heating and thermal decomposition of the unreacted residue, and energy loss in the reforming furnace can be suppressed.

  Furthermore, in this invention, it is preferable to provide the drying preheating furnace which dries the said waste before thrown into the said gasification furnace with the heat | fever of the water vapor | steam generated with the said heat exchanger.

  Waste may contain 40 to 50% or more of moisture, but when this is put directly into the gasification furnace, most of the effective energy of the waste is used for drying waste. The amount of combustible gas generated may be reduced, but according to this configuration, the amount of heat consumed in the gasification furnace is suppressed by pre-drying and preheating the waste before being put into the gasification furnace. be able to. Further, since the waste is dried and preheated by the heat of steam generated by using the heat of the reformed gas, energy can be used effectively.

  Furthermore, in the present invention, the gasifier is preferably a fluidized bed gasifier.

A fluidized bed gasification furnace is a furnace in which the temperature in the furnace is easily maintained at a temperature at which waste is easily pyrolyzed as compared with other types of furnaces such as a stoker type furnace. That is, according to this configuration, by using a fluidized bed type gasification furnace, it is possible to generate a larger amount of pyrolysis gas stably than other types of furnaces.
If a fluidized bed gasification furnace is used as the gasification furnace and the fluidizing gas of the sand layer is, for example, air, the amount of air for causing the sand layer to flow and the amount of air required for partial combustion do not necessarily match. However, if a large amount of air (including oxygen) was introduced for the flow of the sand layer, there was a problem that the oxidation reaction (combustion) proceeded too much and the temperature of the sand layer increased too much. On the other hand, when water vapor is used as the gas supplied into the fluidized bed gasification furnace, both a good fluidized state of the sand layer and an appropriate temperature state of the sand layer can be achieved.

  Moreover, according to the 2nd aspect, this invention provides the waste power generation equipment provided with the combustible gas production | generation apparatus of this invention, and the cogeneration system operated by the said reformed gas. According to this waste power generation facility, it is possible to dramatically increase the energy recovery rate than before.

  Furthermore, according to the third aspect of the present invention, there is provided a gasification step of thermally decomposing a waste charged in the gasification furnace to generate a pyrolysis gas, and at least one of the generated pyrolysis gases. A gas reforming step in which unreacted residue is thermally decomposed in a reforming furnace to generate a reformed gas, steam is generated using heat of the generated reformed gas, and the steam is converted into the gasifier. Provided is a method for producing a combustible gas, comprising: a steam supply process for supplying steam into the interior; and a steam separation process for condensing and discharging steam contained in the reformed gas.

  According to this configuration, the steam is used for the thermal decomposition of the waste in the gasification furnace, and then the steam contained in the reformed gas is condensed, separated from the reformed gas, and discharged, thereby combustible in the reformed gas. The ratio of the components can be increased, and as a result, the calorific value of the reformed gas can be increased as compared with the conventional case. Further, since the steam for use in the thermal decomposition of the waste is generated using the heat of the reformed gas, the energy recovery rate can be increased.

  In the present invention, the water vapor separation step is preferably a step of lowering the temperature of the reformed gas to 60 ° C. or lower by a gas cleaning device.

  According to this configuration, the reformed gas is washed and the water vapor (water) contained in the reformed gas is condensed and separated and removed. Thereby, the emitted-heat amount of reformed gas can be raised more. By setting the temperature of the reformed gas to 60 ° C. or less, the amount of water vapor (moisture) contained in the reformed gas is about 20% or less, and the amount of heat of the reformed gas can be increased. It can be suitably used for a turbine.

  Furthermore, in the present invention, an unreacted residue separation step for separating unreacted residue and gas in the pyrolysis gas generated in the gasification furnace, and an unreacted state for supplying the separated unreacted residue to the reforming furnace A residue supplying step.

  According to this configuration, most of the workpieces supplied to the reforming furnace become unreacted residues. Therefore, most of the heat applied in the reforming furnace can be used for heating and thermal decomposition of the unreacted residue, and energy loss in the reforming furnace can be suppressed.

  Furthermore, in the present invention, the gasifier is preferably a fluidized bed gasifier.

  As described above, the fluidized bed gasification furnace is a furnace in which the temperature in the furnace is easily maintained at a temperature at which waste is easily pyrolyzed as compared with other types of furnaces such as a stoker type furnace. That is, according to this configuration, by using a fluidized bed type gasification furnace, it is possible to generate a larger amount of pyrolysis gas stably than other types of furnaces.

  Hereinafter, embodiments for carrying out the present invention will be described with reference to the drawings. FIG. 1 is a block diagram of a waste power generation facility 101 including a combustible gas generation device 100 according to an embodiment of the present invention.

(Combustible gas generator configuration)
As shown in FIG. 1, the combustible gas generator 100 of this embodiment includes a dust feeder 1, a dry preheating furnace 2, a fluidized bed gasification furnace 3, and a plasma furnace 4 in order from the upstream side of the treatment process. A heat exchanger 5, a bag filter 6, a scrubber 7, and a gas holder 8.

(Dust feeder)
The dust feeder 1 supplies waste to the drying preheating furnace 2 quantitatively, and for example, a screw conveyor type is used. Here, in this embodiment, the waste mixed with municipal waste and waste plastic (hereinafter referred to as mixed waste) is processed to generate combustible gas (for example, CO, H ₂ , CH _4, etc.). . Municipal waste is a low-calorie waste with a relatively low calorific value, and waste plastic is a high-calorie waste with a high calorific value compared to municipal waste. Combustible gas with a higher calorific value can be generated by using mixed waste mixed with waste plastic, which is high-calorie waste, in municipal waste. In general, municipal waste has large fluctuations in its properties, so the fluctuation in the calorific value of the generated combustible gas also becomes large. However, waste plastics with no variation in properties compared with municipal waste are mixed and used. As a result, it is possible to suppress the fluctuation of the calorific value of the generated combustible gas by five. Note that the object to be treated is not limited to municipal waste, and various general wastes, industrial wastes, and the like can be targeted. In addition to waste plastics, high-caloric waste mixed with municipal waste includes dehydrated sludge, waste tires, waste paper, rubber, waste oil, waste oil sludge, and woody biomass discharged from sewage treatment facilities.

  Further, a crusher (not shown) is disposed either before or after the dust feeder 1, and municipal waste and waste plastic are crushed by the crusher. By being finely crushed, the drying efficiency in the subsequent drying preheating furnace 2 is also improved, and the thermal decomposition efficiency in the fluidized bed gasification furnace 3 is also improved. Thus, by improving the thermal decomposition efficiency, the amount of unreacted residues such as char and tar generated in the fluidized bed gasification furnace 3 can be reduced, and the amount of combustible gas in the fluidized bed gasification furnace 3 can be reduced. An increase in the amount generated can be expected. In addition, the municipal waste and waste plastic which were crushed are once put in a pit or a yard, and then supplied to the drying preheating furnace 2 by the dust feeder 1.

(Drying preheating furnace)
The drying preheating furnace 2 is for heating and drying the mixed waste before the mixed waste is put into the fluidized bed gasification furnace 3. An example of the drying preheating furnace 2 is an external heating kiln. For drying and preheating of the mixed waste, water vapor obtained by recovering heat generated in the plasma furnace 4 in the subsequent stage by the heat exchanger 5 is used. Further, the mixed waste is dried and preheated, so that the water vapor is condensed into water, but is discharged to the condensed water tank 10 connected to the drying preheating furnace 2 and supplied to the heat exchanger 5 again by the pump P. It will be. Further, the water vapor from the heat exchanger 5 is also supplied to the fluidized bed gasification furnace 3, and the water vapor is drained out of the system. Therefore, when the amount of water in the condensed water tank 10 falls below a predetermined amount, the condensed water tank 10 is replenished with water. In addition, when the calorific value which the waste which is a process target has is high, the drying preheating furnace 2 may not be provided.

(Gasification furnace)
The fluidized bed gasification furnace 3 is for pyrolyzing the mixed waste introduced from the drying preheating furnace 2 to generate pyrolysis gas. A sand layer 31 which is a fluidized bed is provided on the hearth of the fluidized bed gasification furnace 3. The fluidized bed gasification furnace 3 is formed so that water vapor and oxygen are supplied from the furnace bottom. Furthermore, when the temperature of water vapor introduced from the bottom of the furnace is low, a heating mechanism for heating the bottom of the fluidized bed gasification furnace (for example, providing a jacket outside the furnace bottom and heating from the outside or a burner directly) It may be provided. In addition to the fluidized bed type gasification furnace 3, for example, a fixed bed type gasification furnace or a stoker type furnace can be used. It is possible to use a fluidized bed gasifier because waste can be efficiently partially burned in a state of low oxygen concentration to generate more combustible gas and it is easy to maintain at 700 ° C or higher. preferable.

  Here, the fluidized bed gasifier 3 is preferably operated at an oxygen ratio of 0.1 to 0.5, and the operating temperature of the fluidized bed gasifier is a temperature of the sand layer of 400 ° C to 800 ° C, Furthermore, it is preferable to set it as 500 to 750 degreeC, Furthermore, it is set as 700 to 750 degreeC. Further, the temperature of the upper part of the fluidized bed gasifier (the free board part above the sand layer) is preferably 650 to 900 ° C, more preferably 700 to 900 ° C, and further preferably 800 to 900 ° C. When the temperature of the sand layer is 400 ° C. or lower, tar and char are likely to be generated, and it is difficult to efficiently gasify waste and take out combustible gas. On the other hand, when the temperature exceeds 800 ° C., the sand layer may be baked and hardened due to the influence of the salt contained in the waste, and the sand layer may not be fluidized and cannot be operated.

  On the other hand, in the free board portion, when the temperature is 400 ° C. or lower, tar and char are not decomposed, so that the amount of combustible gas generated may be reduced. By setting the temperature of the freeboard part to 650 ° C or higher, further 700 ° C or higher, and further 800 ° C or higher, tar and char once generated can be pyrolyzed in the freeboard part, The amount of combustible gas generated can be increased. The oxygen ratio refers to the ratio of the set supply oxygen amount to the minimum necessary oxygen amount required for completely burning the waste.

(Reforming furnace)
The plasma furnace 4 is a reforming furnace for generating reformed gas by thermally decomposing tar and unreacted residues (mainly char) in the pyrolysis gas generated in the fluidized bed gasification furnace 3 with plasma. There is a plasma torch for generating the plasma. The reforming furnace does not use plasma (no plasma torch is provided), and is heated at a temperature higher than the temperature in the preceding fluidized bed gasification furnace 3 by blowing air into a heating furnace or furnace using microwaves. A furnace to be operated (for example, a swirl melting furnace) may be used. In this case, the air ratio is about 0.1 to 0.3. Here, the air ratio refers to the ratio of the set supply air amount to the minimum necessary air amount required for completely burning the waste. Note that oxygen may be blown into the furnace (for example, a swirl melting furnace) instead of air. In this case, the oxygen blowing amount uses the expression oxygen ratio, and the value is about 0.1 to 0.3. When air is used, the reformed gas in which nitrogen in the air is generated may be diluted. However, the use of oxygen can prevent dilution of the reformed gas.

  When a plasma furnace is used as a reforming furnace, the amount of exhaust can be reduced and the equipment becomes compact, and when a swirling melting furnace is used, the power consumption of the equipment can be reduced and the power transmission end efficiency can be increased. effective. The temperature of the reforming furnace is preferably 800 to 1100 ° C. If it is 800 ° C. or lower, char and tar generated in the gasifier cannot be decomposed, and if it is 1100 ° C. or higher, useless heat is used to melt char and ash, The calorific value of the resulting reformed gas is reduced.

(Heat exchanger)
The heat exchanger 5 uses the heat of the reformed gas generated in the plasma furnace 4 (in other words, heat generated in the plasma furnace 3) to the fluidized bed gasification furnace 3 and the drying preheating furnace 2. This is for generating water vapor to be supplied. Water is supplied from the condensed water tank 10 to the heat exchanger 5 by a pump P. An example of the heat exchanger 5 is a steam boiler. However, the reformed gas contains chlorine and the like, and there are restrictions on the material selection in a steam boiler having a normal water pipe. Here, the water vapor generated in the present embodiment is used for drying mixed waste or fluidizing gas in the fluidized bed gasification furnace 3. Therefore, when high temperature and high pressure are not required for the water vapor, a jacket type heat exchanger that generates water vapor through a water pipe on the back side of the duct provided with a refractory material may be used. The steam generated in these heat exchangers (steam boiler or jacket type heat exchanger) is supplied to the fluidized bed gasification furnace 3 and the drying preheating furnace 2 by a blower (not shown).

  The amount of water vapor generated in the heat exchanger 5 is larger than the amount of water vapor consumed in the fluidized bed gasification furnace 3 and the drying preheating furnace 2, and there is a sufficient amount of excess water vapor to rotate the steam turbine. Alternatively, a steam path may be newly branched from a steam path connecting the heat exchanger 5 to the fluidized bed gasification furnace 3 and the drying preheating furnace 2, and a steam turbine for power generation may be provided there. According to this configuration, since it is possible to further generate power using surplus steam, the power generation amount of the entire system can be improved.

(Bug filter)
The bag filter 6 is for removing dust contained in the reformed gas generated in the plasma furnace 4, and is provided in the subsequent stage of the heat exchanger 5.

(Gas cleaning device)
The scrubber 7 (gas cleaning device) plays a role of condensing and discharging water vapor contained in the reformed gas generated in the plasma furnace 4 and a role of removing acidic gas contained in the reformed gas. Steam separation means. The scrubber 7 is formed so that an alkali agent (for example, an aqueous sodium hydroxide solution) is supplied into the scrubber from its upper part. The condensed water condensed with water vapor is discharged out of the system from the drain of the scrubber 7. The scrubber 7 is provided after the bag filter 6. In this embodiment, the scrubber 7 is designed so that the temperature of the reformed gas that has passed through the scrubber 7 is about 60 ° C.

  The condensed water from the scrubber 7 is preferably neutralized and filtered (for example, sand filtration and / or membrane filtration) and used as makeup water for generating water vapor. By using scrubber wastewater as makeup water for steam in this way, the amount of waste (in this case, wastewater) discharged from the processing device to the outside of the system can be reduced. The amount of makeup water to be introduced can also be reduced.

(Gas holder)
The gas holder 8 stores the reformed gas (combustible gas) that has exited the scrubber 7, and is disposed at the rear stage of the scrubber 7.

(Configuration of waste power generation facilities)
Next, the configuration of the waste power generation facility 101 will be described with reference to FIG. The waste power generation facility 101 is obtained by adding a gas engine 9 to the combustible gas generation device 100 described above.

(Gas engine)
The gas engine 9 is operated using the reformed gas (combustible gas) supplied from the gas holder 8 as a fuel gas, and generates power by turning the generator G (generator). On the other hand, the gas engine 9 uses the exhaust heat to generate steam and heat ( This is a cogeneration system that takes out hot water. As a cogeneration system, a gas turbine may be used instead of the gas engine 9 or a fuel cell may be used.

(Combustible gas production method)
Next, the manufacturing method of the combustible gas using the combustible gas production | generation apparatus 100 is demonstrated.

(Waste supply process)
First, mixed waste obtained by mixing municipal waste and waste plastic is quantitatively supplied to the drying preheating furnace 2 by the dust feeder 1. The mixed waste is supplied to the drying preheating furnace 2 in a state of being crushed by a crusher (not shown) disposed either before or after the dust feeder 1.

(Drying process)
Next, the mixed waste is dried and preheated in the drying preheating furnace 2. For drying and preheating of the mixed waste, the heat of water vapor sent from the heat exchanger 5 is used. Specifically, an indirect heating type rotary kiln or the like is used, mixed waste is supplied into a rotating cylindrical container, steam is supplied into a jacket covering the cylindrical container, and the mixed waste is generated by the heat of the steam. It is heated indirectly. The drying preheating furnace is not particularly limited to a rotary kiln, and may be any furnace that can indirectly heat waste with the heat of steam. The mixed waste is preheated to about 200 ° C. Here, the amount of heat consumed in the fluidized bed gasification furnace 3 can be suppressed by drying and preheating the mixed waste before being charged into the fluidized bed gasification furnace 3 in advance. Further, the mixed waste is easily dispersed in the fluidized bed gasification furnace 3, and the thermal decomposition efficiency of the mixed waste is improved.

  The drying temperature is not particularly limited to 200 ° C. and may be any temperature that can reliably evaporate water, or any temperature that does not cause thermal decomposition in the drying stage. As such a temperature, it is preferable to heat the mixed waste to 100 ° C to 220 ° C, and further to 120 ° C to 200 ° C.

(Gasification process)
The mixed waste preheated to about 200 ° C. is put into the fluidized bed gasifier 3. In the mixed waste gasification step, the oxygen ratio is set to 0.1 to 0.5, and the temperature of the sand layer 31 of the fluidized bed gasification furnace 3 is maintained at about 700 ° C. to heat the mixed waste. Decompose. Here, the water vapor sent from the heat exchanger 5 is supplied into the furnace from the furnace bottom to cause the sand layer 31 to flow. In addition, oxygen is supplied from the furnace bottom to partially burn the mixed waste. Incombustible materials contained in mixed waste are extracted from the furnace bottom and discharged out of the system.

  Here, when a fluidized bed type gasification furnace is used for the gasification furnace, it is necessary to input the fluidization gas into the gasification furnace in order to cause the sand layer to flow, but the amount of air for fluidizing the sand layer is large. Since it is larger than the amount of air required for partial oxidation, if a large amount of air is introduced for fluidization, the oxidation reaction (combustion) proceeds too much in the gasification furnace, and the temperature of the sand layer tends to increase too much. Moreover, there exists a possibility of diluting the combustible gas which nitrogen in the air generate | occur | produced. In particular, when the ratio of waste plastics that are high calorific waste in mixed waste is high (when the calorie of mixed waste is high), air (containing oxygen) is used instead of water vapor as the gas for flowing the sand layer 31. As described above, the temperature of the sand layer 31 may rise too much, and the sand layer 31 may be baked and solidified and may not flow. On the other hand, if water vapor is used, heat generation due to combustion can be suppressed, and the sand layer temperature can be maintained at a certain temperature or lower even for high-calorie waste. That is, when the waste to be treated is high in calories, water vapor is suitable as the gas for causing the sand layer 31 to flow. Further, since air contains a large amount of nitrogen, the generated pyrolysis gas is diluted with nitrogen, and the heat generation amount is reduced. On the other hand, when water vapor is used, water vapor can be easily separated in a subsequent water vapor separation step. Moreover, generation | occurrence | production of the combustible gas by water gasification reaction can be anticipated. Furthermore, the sand layer can be sufficiently fluidized with water vapor. Also from this viewpoint, water vapor that is easy to separate and remove is suitable as the gas for flowing the sand layer 31. In the present embodiment, the amount of combustible gas obtained can be increased by using steam to flow the fluidized bed and separately supplying the minimum necessary oxygen for partial oxidation of the waste.

(Gas reforming process)
The pyrolysis gas at about 700 ° C. generated in the fluidized bed gasification furnace 3 then enters the plasma furnace 4. This pyrolysis gas contains tar and unreacted residues (mainly char). These tars and unreacted residues are pyrolyzed by plasma at about 1000 ° C. in the plasma furnace 4, and the pyrolysis gas generated in the fluidized bed gasification furnace 3 is reformed (becomes reformed gas).
In general, air is often used as the plasma furnace, but it is preferable to use a plasma furnace using steam, hydrocarbons, or the like from the viewpoint of maintaining or improving the amount of heat of the combustible gas. This is because when water vapor is used, water vapor is mixed into the combustible gas, but there is no risk of dilution of the combustible gas because the water vapor is removed in the subsequent water vapor separation step, and the water gasification reaction It can also be expected that the amount of combustible gas will increase due to the above, and as a result, the amount of heat of the combustible gas can be maintained or improved. Further, when hydrocarbon is used, it is considered that combustible gas is generated along with the decomposition of the hydrocarbon, and as a result, the amount of heat of the combustible gas can be improved.

(Steam supply process)
The reformed gas at about 1000 ° C. reformed in the plasma furnace 4 is supplied to the heat exchanger 5. On the other hand, water is supplied from the condensed water tank 10 to the heat exchanger 5. In the heat exchanger 5, heat is transferred from the high-temperature reformed gas to water, and the water becomes steam, and the temperature of the reformed gas is reduced to about 200 ° C. The generated steam is supplied to the fluidized bed gasification furnace 3 and the drying preheating furnace 2.

(Dust removal process)
The reformed gas at about 200 ° C. is supplied to the bag filter 6 to remove dust contained in the reformed gas.

(Steam separation process)
Next, the reformed gas that has passed through the bag filter 6 is supplied to the scrubber 7. The reformed gas comes into contact with the sodium hydroxide aqueous solution in the scrubber 7 to remove the acidic gas in the reformed gas, and the temperature of the reformed gas is lowered to condense and remove the water vapor in the reformed gas. . The condensed water is discharged out of the system from the drain below the scrubber 7. As described above, the condensed water is preferably reused as make-up water after a certain treatment.

  Here, the temperature of the reformed gas is lowered to about 60 ° C. by passing the reformed gas through the scrubber 7. Thus, the temperature of the reformed gas is preferably lowered to 60 ° C. or lower. More preferably, it is lowered to 40 ° C. or lower. The lower limit temperature is room temperature. The reformed gas (combustible gas) exiting the scrubber 7 is stored in the gas holder 8. By setting the temperature of the reformed gas to 60 ° C. or less, the amount of water vapor (moisture) contained in the reformed gas is about 20% or less, and by changing the temperature of the reformed gas to 40 ° C. or less, it is included in the reformed gas. The amount of water vapor generated can be 7% or less. As a result, the steam added in the fluidized bed gasifier can be recovered and reused, and the steam can be removed and the concentration of the reformed gas can be increased, so that the calorific value of the resulting reformed gas can be increased. it can. Moreover, since the volume is reduced by removing water vapor, the downstream gas holder can also be reduced.

  As described above, according to the combustible gas generator 100, water vapor is used for the thermal decomposition of the mixed waste in the fluidized bed gasification furnace 3, and then the water vapor contained in the reformed gas is condensed in the scrubber 7. Thus, by separating and discharging from the reformed gas, the ratio of combustible components in the reformed gas can be increased, and as a result, the calorific value of the reformed gas can be increased more than before. Further, since the steam of the reformed gas is used to generate waste water for drying and pyrolysis of the waste, the energy recovery rate can be increased.

(Gas power generation)
A reformed gas (combustible gas) is supplied from the gas holder 8 to the gas engine 9, and the gas engine 9 is operated to generate electric power. Further, steam or warm heat (hot water) is taken out using the exhaust heat of the gas engine 9. According to the waste power generation facility 101 using the gas engine 9, the energy recovery rate can be dramatically increased as compared with the conventional case.

(Other embodiments)
FIG. 2 is a block diagram showing another embodiment of the combustible gas generator and the waste power generation facility of the present invention. The present embodiment will be described with emphasis on the differences from the above embodiment. Moreover, the same code | symbol is attached | subjected about the same component apparatus as the component apparatus of the said embodiment.

(Combustion gas generator and waste power generation equipment configuration)
The main difference between the combustible gas generation device 102 of this embodiment and the waste power generation facility 103 including the same, and the combustible gas generation device 100 and the waste power generation facility 101 of the above-described embodiment is that the combustible gas generation according to this embodiment is performed. The apparatus 102 and the waste power generation facility 103 are provided with the cyclone 11 (unreacted residue separation means).

(Unreacted residue separation means)
The cyclone 11 swirls the pyrolysis gas from the fluidized bed gasification furnace 3 inside and separates unreacted residues (mainly char) in the pyrolysis gas using centrifugal force and gravity. is there. The cyclone 11 is disposed between the fluidized bed gasification furnace 3 and the plasma furnace 4. The unreacted residue separated from the pyrolysis gas is supplied to the plasma furnace 4 from the bottom of the cyclone 11. On the other hand, the pyrolysis gas from which the unreacted residue has been removed is directly introduced into the heat exchanger 5 from the upper part of the cyclone 11 without passing through the plasma furnace 4.

(Unreacted residue supply means)
Further, the combustible gas generator 102 includes a screw feeder 13. The screw feeder 13 is unreacted residue supply means for supplying unreacted residues separated in the cyclone 11 to the plasma furnace 4. The screw feeder 13 is installed near the outlet of the cyclone 11. Examples of the unreacted residue supply means include a pusher in addition to the screw feeder 13.

(Combustible gas production method)
In the present embodiment, the entire amount of the pyrolysis gas generated in the fluidized bed gasification furnace 3 is not supplied to the plasma furnace 4 as it is, but unreacted residues separated from the pyrolysis gas are removed from the plasma furnace 4. The pyrolysis gas from which the unreacted residue has been removed is introduced into the heat exchanger 5 without passing through the plasma furnace 4.

(Unreacted residue separation step)
The pyrolysis gas generated in the fluidized bed gasification furnace 3 is first supplied to the cyclone 11. In the cyclone 11, unreacted residues in the pyrolysis gas are separated.

(Unreacted residue supply process)
Next, the unreacted residue separated in the cyclone 11 is extracted from the bottom of the cyclone 11 by the screw feeder 13 and supplied to the plasma furnace 4. Here, the supply of the unreacted residue to the plasma furnace 4 may be a continuous type or a batch type. The continuous type means that the screw feeder 13 is always operated to continuously supply unreacted residues to the plasma furnace 4. On the other hand, in the batch type, when a predetermined amount of unreacted residue is accumulated at the bottom of the cyclone 11, the screw feeder 13 is operated to supply the unreacted residue to the plasma furnace 4, and the unreacted residue at the bottom of the cyclone 11 is reduced to a predetermined amount or less. This means an operation method for stopping the screw feeder 13 when it becomes.

The supply of the unreacted residue to the plasma furnace 4 may be a gas transport method using a part of the pyrolysis gas generated in the fluidized bed gasification furnace 3 instead of the screw feeder 13 and the pusher. . A gas transport pipe 12 indicated by a dotted line in FIG. 2 may be provided, and unreacted residues may be extracted from the bottom of the cyclone 11 by the suction action by the flow of pyrolysis gas and supplied to the plasma furnace 4. Also in this gas transport system, the supply of the unreacted residue to the plasma furnace 4 may be a continuous system or a batch system. The timing of extracting unreacted residues from the bottom of the cyclone 11 can be adjusted by a valve (not shown) provided in the gas transport pipe 12 or the like.
In addition, it is good also as a structure which provides an unreacted residue storage part separately in the back | latter stage of a cyclone, and stores the unreacted residue isolate | separated with the cyclone in an unreacted residue storage part.

  Next, the pyrolysis gas from which the unreacted residue has been removed by the cyclone 11 and the reformed gas reformed in the plasma furnace 4 are mixed before the heat exchanger 5, and the mixed gas is used as the heat exchanger. Enter 5.

  According to the present embodiment, the unreacted residue is separated from the pyrolysis gas exiting the fluidized bed gasification furnace 3 and only the object to be processed that contains a large amount of unreacted residue is supplied to the plasma furnace 4. It is difficult to use the heat applied in the process for heating the combustible gas, and most of the heat can be used for heating the unreacted residue and the thermal decomposition reaction, and energy loss in the reforming furnace can be greatly suppressed. Further, since the amount of gas supplied to the reforming furnace is reduced, the furnace can be downsized.

As the reforming furnace, a heating furnace (microwave heating furnace) using a microwave may be used instead of the plasma furnace 4 or the swirl melting furnace. When a microwave heating furnace is used, the reformed gas generated in the reforming furnace is difficult to be diluted. When the reforming furnace is, for example, a swirling melting furnace, it is necessary to supply air (or oxygen) into the furnace, and even in the case of the plasma furnace 4, air or the like is required as a working gas. On the other hand, the microwave heating furnace does not particularly require these gases.
Furthermore, since char and tar to be pyrolyzed easily absorb microwaves, the use of microwaves has the advantage that char and tar can be heated efficiently and evenly. In addition, there is little energy loss when heating.

  In addition, when the supply of unreacted residue to the reforming furnace is a batch type, it is necessary to keep the temperature in the reforming furnace at a constant high temperature even when the temperature in the reforming furnace is not operated. There is also the possibility of frequent shutdowns. When a microwave heating furnace is used as the reforming furnace, the microwave heating furnace has an advantage that the operation can be easily started and stopped without performing complicated operations.

  In this embodiment, tar is not particularly described. However, what is supplied to the reforming furnace together with the unreacted residue is decomposed in the reforming furnace as in the first embodiment, and becomes reformed gas. Moreover, in order to isolate | separate the tar conveyed by pyrolysis gas at an unreacted residue separation process, it is good also as a structure which installs an adsorbent separately. In this case, the tar can be decomposed by putting the adsorbent adsorbing the tar into a gasification furnace or a reforming furnace.

Although the embodiments of the present invention have been described above, the present invention is not limited to the above-described embodiments, and various modifications can be made as long as they are described in the claims. .
For example, in this embodiment, the reformed gas that has passed through the heat exchanger is directly introduced into the bag filter. However, if the temperature of the reformed gas cannot be sufficiently reduced by the heat exchanger, the reformed gas is reduced to the front stage of the bag filter. A temperature tower may be provided to lower the temperature of the reformed gas.

It is a block diagram of the waste power generation equipment provided with the combustible gas production | generation apparatus which concerns on one Embodiment of this invention. It is a block diagram which shows other embodiment of the combustible gas production | generation apparatus and waste power generation equipment of this invention.

Explanation of symbols

1: Dust feeder 2: Drying preheating furnace 3: Fluidized bed gasification furnace 4: Plasma furnace 5: Heat exchanger 7: Scrubber 100: Combustible gas generator 101: Waste power generation facility

Claims (10)

A gasification furnace for pyrolyzing the input waste to generate pyrolysis gas;
A reforming furnace for pyrolyzing at least unreacted residue in the pyrolysis gas generated in the gasification furnace to generate a reformed gas;
A heat exchanger that generates steam to be supplied into the gasification furnace using heat of the reformed gas generated in the reforming furnace;
Water vapor separation means for condensing and discharging water vapor contained in the reformed gas;
A combustible gas generator. In the combustible gas generator according to claim 1,
The combustible gas generating device, wherein the water vapor separating means is a gas cleaning device that further reduces the temperature of the reformed gas that has flowed through the heat exchanger to a temperature of 60 ° C. or lower. In the combustible gas generating device according to claim 1 or 2,
Separation means for separating unreacted residue and gas in the pyrolysis gas generated in the gasification furnace;
Unreacted residue supply means for supplying unreacted residue separated by the separation means to the reforming furnace;
A combustible gas generation device comprising: In the combustible gas generating device according to any one of claims 1 to 3,
A combustible gas generating apparatus comprising a drying preheating furnace that dries the waste before being put into the gasification furnace with the heat of water vapor generated in the heat exchanger. In the combustible gas production | generation apparatus in any one of Claims 1-4,
The combustible gas generator, wherein the gasifier is a fluidized bed gasifier. A combustible gas generator according to any one of claims 1 to 5,
A cogeneration system operated by the reformed gas;
A waste power generation facility. A gasification process for generating pyrolysis gas by pyrolyzing the waste put into the gasification furnace;
A gas reforming step of generating a reformed gas by thermally decomposing at least an unreacted residue in the generated pyrolysis gas in a reforming furnace;
A steam supply step of generating steam using heat of the generated reformed gas and supplying the steam into the gasification furnace;
A water vapor separation step of condensing and discharging water vapor contained in the reformed gas;
A method for producing a combustible gas. In the combustible gas manufacturing method of Claim 7,
The method for producing a combustible gas, wherein the water vapor separation step is a step of lowering the temperature of the reformed gas to 60 ° C. or less by a gas cleaning device. In the combustible gas manufacturing method of Claim 7 or 8,
An unreacted residue separation step for separating unreacted residue and gas in the pyrolysis gas generated in the gasification furnace;
An unreacted residue supply step of supplying the separated unreacted residue to the reforming furnace;
A combustible gas production method comprising: In the combustible gas manufacturing method in any one of Claims 7-9,
The method for producing a combustible gas, wherein the gasification furnace is a fluidized bed gasification furnace.

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