WO2015079563A1 - Gasification furnace for generating flammable fuel gas - Google Patents

Abstract

[Problem] To provide a gasification furnace in which the formation of tar can be prevented more effectively. [Solution] A gasification furnace (10), in which a flammable gas can be generated by supplying a fuel containing a component that can be converted to tar into an internal space (10a), burning the fuel in an oxidizing layer in the internal space (10a) while controlling the volume of air and then reducing the burned fuel in a reducing layer in the space, wherein a thermally decomposing layer is provided in the internal space (10a), the thermally decomposing layer is connected to the oxidizing layer, the fuel that is not yet burned in the oxidizing layer is stored in the thermally decomposing layer, the fuel is thermally decomposed by heating while supplying no air in the thermally decomposing layer, the gasification furnace (10) is provided with a gas supply unit (22) and an air supply unit (20) which respectively supply a gas and air both for burning purposes, which can thermally decompose the heated fuel at a temperature lower than the temperature of the burning in the oxidizing layer, to a zone located on the oxidizing layer side in the thermally decomposing layer, and air is supplied from the air supply unit (20) while controlling the volume of the air.

Description

Gasification furnace that produces flammable fuel gas

The present invention relates to a gasification furnace that generates combustible fuel gas.

From the viewpoint of effective use of woody biomass, research has been conducted on generating fuel gas from woody biomass. Since woody biomass contains a causative substance that generates tar, the fuel gas contains tar.

As a technique for reducing tar contained in fuel gas, Patent Document 1 discloses that two air blowing members are arranged above and below the radial center in the combustion space, and fuel (woody biomass) is placed above the combustion space. Etc.) is subjected to carbonization and oxidative decomposition of the carbonization gas containing fuel gas and tar under the combustion space is described.

JP 2005-89519 A

In the apparatus of Patent Literature 1, although the tar contained in the fuel gas can be reduced by expanding the oxidation layer for decomposing the tar generated by the thermal decomposition upward, it is generated when the fuel gas is generated. It is required to further reduce the amount of tar.

This invention is made | formed in view of such a situation, The objective is providing the gasification furnace which can suppress generation | occurrence | production of tar more in the gasification furnace which produces | generates combustible fuel gas. It is in.

In order to achieve the above object, the present invention generates a combustible gas by reducing a fuel containing tar components supplied to an internal space while restricting the amount of air in a reducing layer in the internal space. A gasification furnace that is connected to an oxide layer in the internal space, stores the fuel before being burned in the oxide layer, and is heated and thermally decomposed without air being supplied. A combustion layer and a gas for thermally decomposing the heated fuel having a decomposition layer in the internal space at a temperature lower than the combustion in the oxidation layer, and the oxidation in the thermal decomposition layer The gasification furnace includes a gas supply unit and an air supply unit that supply a layer-side region, and air is supplied from the air supply unit while the amount of air is limited.

According to such a gasification furnace, the fuel stored in the pyrolysis layer and heated in a state where no air is supplied includes a combustion gas for thermal decomposition at a temperature lower than that in the oxidation layer. Air is supplied from the gas supply unit and the air supply unit. At this time, since the amount of air supplied is limited, the fuel stored in the thermal decomposition layer and before reaching the oxide layer is thermally decomposed at a temperature lower than that of the oxide layer. The thermal decomposition at a temperature lower than that of the oxide layer evaporates the tar component before the fuel reaches the oxide layer, so the amount of tar generated when the fuel is reduced in the reduction layer is suppressed. It is possible.

In this gasification furnace, it is preferable that the fuel stored in the pyrolysis layer is heated by heat from which the fuel previously supplied to the oxide layer is combusted.
According to such a gasification furnace, it is possible to heat the fuel without supplying air without separately providing a heat source for heating the fuel stored in the pyrolysis layer.

The gasification furnace preferably includes a heat exchanger that exchanges heat between the fuel stored in the pyrolysis layer and the fuel gas generated by reduction in the reduction layer.
According to such a gasification furnace, the fuel stored in the pyrolysis layer is not only heated by the heat of combustion of the fuel previously supplied to the oxide layer but also generated by the heat exchanger. Since the heating is also performed by exchanging heat with the fuel gas, the heating can be performed more efficiently.

In this gasification furnace, it is desirable that the combustion gas is a part of the fuel gas generated by the reduction in the reduction layer.
According to such a gasification furnace, the fuel is pyrolyzed at a temperature lower than that of the oxide layer. The combustion gas in the pyrolysis layer is a part of the fuel gas generated in the reduction layer. There is no need to supply. That is, since it is not necessary to use fuel separately, the production cost of fuel gas can be suppressed.

The gasification furnace preferably includes a lock hopper type fuel supply unit that communicates with the internal space and supplies the fuel.
According to such a gasification furnace, since the fuel is supplied from the lock hopper type fuel supply unit, it is possible to supply the fuel to the internal space without flowing air.

In such a gasification furnace, the fuel is preferably woody biomass.
According to such a gasification furnace, it is possible to provide a gasification furnace in which generation of tar is suppressed by effectively using woody biomass.

According to the present invention, it is possible to provide a gasification furnace that can further suppress the generation of tar in a gasification furnace that generates combustible fuel gas.

It is a figure which shows the structure at the time of a gasification furnace being installed. It is a longitudinal cross-sectional view of a gasification furnace.

Hereinafter, an embodiment of the present invention will be described in detail. The gasification furnace according to the present invention is a gasification furnace that uses oil-containing seeds (woody biomass) and squeezes fuel oil from dried seeds to gasify the separated oil residue to generate fuel gas. . The oil extraction residue is mixed with dry biomass or the like, formed into a bean-charcoal briquette, and supplied to the gasifier.

The gasifier 10 is installed with a gas cyclone 1, a scrubber 2, a blower 3, and the like as shown in FIG.

The gasification furnace 10 generates fuel gas (gas containing a combustible component such as H ₂ , CO, CH ₄ ) by reducing the organic matter contained in the briquette by heating the briquette with air restricted. To do. The gasification furnace 10 of this embodiment is configured by a downdraft type fixed bed gasification furnace. The reason why the downdraft type gasification furnace 10 is used is that gas can flow downward in the gasification furnace 10 where the briquettes are burned to suppress the diffusion of the flame. The gasification furnace 10 will be described in detail later.

The gas cyclone 1 is a device that removes dust and the like from the generated fuel gas. The scrubber 2 is a device that further removes tar and dust contained in the fuel gas from the gas cyclone 1. The fuel gas is cleaned by the gas cyclone 1 and the scrubber 2. The blower 3 is a part that sucks the purified fuel gas and sends it to a device such as a power generation unit (not shown), and regulates the flow rate of the fuel gas.

Since briquettes contain a large amount of seed residues after oil extraction, when briquettes are supplied to the gasification furnace 10 and reduced in the gasification furnace 10 to produce combustible fuel gas, organic substances contained in the residues are tar. It is easy to become.

Therefore, in the gasification furnace 10 of the present embodiment, the briquette is heated in the thermal decomposition layer located on the oxide layer in the gasification furnace 10 and the air amount is limited at a temperature lower than the combustion in the oxide layer. By thermally decomposing, components that tend to become tar by the reduction in the reduction layer are evaporated, and fuel gas can be generated while suppressing the generation of tar. Hereinafter, the gasification furnace 10 will be described in detail.

The gasification furnace 10 shown in FIG. 2 has a storage pyrolysis unit 11, a cylindrical combustion unit 12, an ash storage unit 13, and a screw conveyor 14. And from the upper side of the gasification furnace 10, the storage pyrolysis part 11, the cylindrical combustion part 12, the ash storage part 13, and the screw conveyor 14 are arrange | positioned in order. The gasification furnace 10 has a cylindrical shape extending from the storage pyrolysis unit 11 to the cylindrical combustion unit 12, and an internal space 10a penetrating in the vertical direction is formed at the center thereof.

The storage pyrolysis part 11 is a cylindrical member produced by covering the outer peripheral part of a heat-resistant member (for example, rock wool) formed in a cylindrical shape with a heat-resistant metal, and is recessed on the outer peripheral side on the inner peripheral surface side. An annular recess 15a is provided, and the recess 15a is closed by an annular heat-resistant metal 15b having the same inner diameter as the inner peripheral surface of the heat-resistant member. That is, on the inner peripheral side of the storage pyrolysis unit 11, an annular space 15c in which the upper and lower surfaces and the outer peripheral surface are formed of a heat-resistant member and the inner peripheral surface is surrounded by a heat-resistant metal 15b. Is formed. For this reason, the annular space 15c is disposed so as to surround the internal space 10a via the heat-resistant metal 15b. The heat-resistant member located on the outer peripheral side of the annular space 15c is provided with two communication pipes 16 and 17 that allow communication between the outside of the gasification furnace 10 and the inside of the annular space 15c. The two communication pipes 16 and 17 are provided so as to form a substantially straight line at positions spaced apart by about 180 degrees in the circumferential direction of the stored pyrolysis unit 11.

Of the two communication pipes 16, 17, the communication pipe 17 is connected to a discharge port 13 b for the fuel gas generated in the gasification furnace 10, and the communication pipe 16 is provided outside the gasification furnace 10. Connected to the scrubber 2. That is, the fuel gas generated in the reduction layer is supplied from one communication pipe 16 and discharged from the other communication pipe 17 into the annular space 15 c provided in the storage pyrolysis unit 11. At this time, the fuel gas flowing through the annular space 15c has a higher temperature than the briquette filled in the internal space 11a of the stored pyrolysis unit 11 due to combustion by the oxide layer. Therefore, when the fuel gas flows in the annular space 15c, the briquette is heated by heat exchange between the fuel gas and the briquette filled in the internal space 11a of the stored pyrolysis unit 11. . Here, the heat exchanger 15 corresponds to a portion that forms the inner heat resistant metal 15b and the annular space 15c partitioned by the heat resistant metal 15b and the inner space 10a.

The internal space 11a of the heat storage member 11 and the heat storage member 11 provided inside the annular space 15c penetrates in the vertical direction. A flange 11b is provided at the lower end of the stored pyrolysis portion 11, and the upper cover 18 is detachably attached to the upper end portion.

A fuel supply unit 19 for supplying briquettes into the gasification furnace 10 connected to the internal space 11 a of the storage pyrolysis unit 11 is provided on the upper portion of the upper cover 18. The fuel supply unit 19 is arranged such that a cylindrical steel pipe 19a penetrates in the vertical direction, and the gate 19b that partitions the inside of the steel pipe 19a at two positions spaced apart from each other in the vertical direction and can be opened and closed independently. 19c is provided. The two gates 19b, 19c are closed with the lower gate 19c closed after the upper gate 19b is closed by filling the upper side with briquettes so that air does not enter as much as possible. This is a so-called lock hopper type fuel supply unit 19 that opens the door and supplies bricks to the storage pyrolysis unit 11.

The internal space 11a of the storage pyrolysis part 11 functions as a dry layer and a thermal decomposition layer. That is, the internal space 11 a communicates with the internal space 12 a of the cylindrical combustion unit 12 and is heated by combustion in the cylindrical combustion unit 12.

The internal space 11a of the storage pyrolysis unit 11 is filled with briquettes supplied by blocking the inflow of air from the fuel supply unit 19. The filled briquettes are heated by heat exchange from the cylindrical combustion section 12 and heat exchange by the heat exchanger 15. By this heating, the temperature of the upper part in the internal space 11a of the storage pyrolysis unit 11 rises (for example, 100 ° C. or more and 300 ° C. or less), the water contained in the briquette evaporates to become water vapor, and the briquette is dried. Therefore, the upper part in the internal space 11a of the stored pyrolysis unit 11 corresponds to a dry layer.

And since the internal space 11a of the storage pyrolysis part 11 becomes high temperature (for example, 300 degreeC or more and 600 degrees C or less), the briquette located under the internal space 11a is thermally decomposed, and the above-mentioned combustible component Is generated. This pyrolysis also produces tar, char, and hydrocarbons from the briquettes. As is clear from the above description, the lower part of the internal space 11a corresponds to a thermal decomposition layer.

Further, the gasification furnace 10 of the present embodiment includes an upper air supply pipe 20 as an air supply unit that supplies air to the oxide layer side of the stored pyrolysis unit 11 and a gas supply unit that supplies fuel gas. A gas supply pipe 22 is provided together with an upper air amount adjustment valve 21 and a gas amount adjustment valve 23 whose valve opening degree can be adjusted. A part (for example, several percent) of the fuel gas flowing into the scrubber 2 through the heat exchanger 15 is gas in the region on the oxide layer side in the pyrolysis layer which is the lower side in the internal space 11a. A slight amount of air whose supply amount is limited by the upper air amount adjusting valve 21 is supplied from the upper air supply tube 20 from the supply tube 22.

The upper air amount adjustment valve 21 adjusts the amount of air flowing through the upper air supply pipe 20 in accordance with the valve opening, and the gas amount adjustment valve 23 opens the amount of fuel gas flowing through the gas supply pipe 22. It is adjusted according to the degree. In the present embodiment, an adjustment valve capable of manually adjusting the valve opening is used, and the amount of air or fuel gas supplied to the pyrolysis layer in the internal space 11a of the stored pyrolysis unit 11 is shut off (fully closed). ) To the maximum (fully open) range.

In the present embodiment, a slight amount of air and fuel gas whose supply amount is limited by restricting the opening degree of the upper air amount adjustment valve 21 are supplied to the pyrolysis layer of the internal space 11a, and briquettes are produced by combustion in the oxidation layer. Thermal decomposition is performed at a low temperature, thereby evaporating the components that become tar contained in the briquette. Here, the upper air supply pipe 20 and the upper air amount adjustment valve 21 correspond to an air supply part, and the gas supply pipe 22 and the gas amount adjustment valve 23 correspond to a gas supply part.

Next, the cylindrical combustion section 12 will be described. The cylindrical combustion unit 12 is a heat-resistant cylindrical member provided between the storage pyrolysis unit 11 and the ash storage unit 13. In the internal space 12a of the cylindrical combustion section 12, the pyrolyzed material supplied from the stored pyrolysis section 11 is burned. That is, the range from the lower air introduction part 24 to the storage pyrolysis part 11 in the internal space 12a of the cylindrical combustion part 12 corresponds to the oxide layer, and is higher than the storage pyrolysis part 11 (for example, 700 ° C. or more and 1200 ° C.). The following is adjusted. In this range, the pyrolyzed briquette undergoes an oxidation reaction (combustion) and is heated. The lower part of the oxidation layer corresponds to a reduction layer, and a combustible component is generated by a reduction reaction caused by the retained heat of the briquette that occurs in a state where oxygen is limited in the reduction layer. Thus, it can be said that the cylindrical combustion part 12 is a member which mainly forms an oxide layer.

The cylindrical combustion part 12 in this embodiment is produced by covering a cylindrical heat-resistant member with a heat-resistant metal, like the stored pyrolysis part 11. In addition, the lower end part of the cylindrical combustion part 12 is joined and integrated with the ash storage part 13.

A lower air introduction part 24 is provided at a position below the center in the height direction of the cylindrical combustion part 12. The lower air introduction part 24 has a plurality of lower air introduction pipes 24 a, and one end side part of these lower air introduction pipes 24 a is radially connected to the cylindrical combustion part 12. In the present embodiment, for example, six lower air introduction pipes 24a are attached at intervals of 60 degrees. Thereby, each lower side air introduction pipe 24a is connected with internal space 12a, and external air is introduced from a plurality of places of peripheral direction in internal space 12a.

Further, a lower air amount adjustment valve (not shown) capable of adjusting the valve opening degree is attached to each of the lower air introduction pipes 24a. The lower air amount adjustment valve adjusts the amount of air flowing through the lower air introduction pipe 24a in accordance with the valve opening. In the present embodiment, an adjustment valve capable of manually adjusting the valve opening is used, and the amount of air supplied to the lower portion of the internal space 12a is arbitrarily set in a range from shut-off (fully closed) to maximum (fully open). Can be adjusted.

Next, the ash storage unit 13 will be described. The ash storage part 13 is connected to the lower end of the cylindrical combustion part 12 and is a part that receives the ash flowing down from the cylindrical combustion part 12. For this reason, the ash storage part 13 is produced with the heat-resistant box-shaped member which forms the internal space 13a used as the storage space. When passing through the lower air introduction part 24 of the cylindrical combustion part 12, the carbide (oxidized briquette) causes a reduction reaction, and a combustible component is generated. Therefore, the lower end part in the internal space 12a of the cylindrical combustion part 12 and the internal space 13a of the ash storage part 13 function as a reducing layer that reduces substances oxidized in the oxidized layer.

The fuel gas containing the combustible component is discharged through the discharge port 13b provided on the upper surface of the ash storage part 13. As described above, the discharged fuel gas passes through the heat exchanger 15 and is purified by the gas cyclone 1 and the scrubber 2, and then a part of the fuel gas is supplied to the stored pyrolysis unit 11. Etc.

Next, the screw conveyor 14 will be described. The screw conveyor 14 discharges the ash after gasification, and is provided below the ash storage part 13. By operating the screw conveyor 14, ash is discharged from the ash storage unit 13. When ash is discharged by the screw conveyor 14, the pyrolyzed briquette flows down into the internal space 12 a of the cylindrical combustion section 12 by an amount corresponding to the amount of ash discharged. For this reason, it can be said that the rotational speed of the screw conveyor 14 regulates the briquette supply speed.

As described above, in the gasification furnace 10 of the present embodiment, the briquette is dried and pyrolyzed by the heat from the cylindrical combustion unit 12 in the storage pyrolysis unit 11, and the component that becomes the tar of the briquette is lower than the oxide layer. Thermal decomposition at temperature. Thereafter, the briquette is oxidized in the cylindrical combustion section 12, and the oxidized briquette is reduced in the process of moving to the ash storage section 13. By undergoing these thermal decomposition, oxidation reaction, and reduction reaction, a combustible substance is generated and finally discharged outside as fuel gas.

And according to this gasification furnace 10, the briquette which is stored in the pyrolysis layer and is heated in a state where no air is supplied is provided with a combustion gas for thermal decomposition at a temperature lower than the combustion in the oxide layer. Air is supplied from an upper air supply pipe 20 and a gas supply pipe 22 including the upper air quantity adjustment valve 21 and the gas quantity adjustment valve 23. At this time, since the amount of air supplied is limited, the briquette before being stored in the thermal decomposition layer and reaching the oxide layer is thermally decomposed at a temperature lower than that of the oxide layer. Due to thermal decomposition at a lower temperature than the oxide layer, the briquette containing the tar component is evaporated before the tar layer reaches the oxide layer. It is possible to reduce the amount of tar to be generated.

In addition, the briquettes stored in the pyrolysis layer are not only heated by the heat of combustion of the briquettes previously supplied to the oxide layer, but also generated fuel gas by the heat exchanger 15. Since it is heated also by heat exchange, it is possible to heat more efficiently. At this time, since the gas supplied to heat the briquettes of the pyrolysis layer is a part of the fuel gas generated by the reduction in the reduction layer, it is not necessary to supply fuel from the outside. That is, since it is not necessary to use fuel separately, the production cost of fuel gas can be suppressed.

Further, since the briquette is supplied from the lock hopper type fuel supply unit 19, it can be supplied to the thermal decomposition layer without causing more air to flow in.

In the gasification furnace 10 of the present embodiment, since the fuel is woody biomass containing components that become tar, it is possible to provide a gasification furnace that effectively uses woody biomass and suppresses the generation of tar. It is.

The above description of the embodiment is intended to facilitate understanding of the present invention and does not limit the present invention. The present invention can be changed and improved without departing from the gist thereof, and the present invention includes equivalents thereof. For example, you may comprise as follows.

Regarding fuel, in the above-described embodiments, briquettes made from seeds after oil extraction are exemplified, but the present invention is not limited thereto. For example, woody biomass such as crushed pieces of wood, rice husks, oil palm empty fruit bunches, sugarcane pomace can be used as fuel.

The screw conveyor 14 may be replaced with another discharging device such as a belt-type conveyor.

1 gas cyclone, 2 scrubber, 3 blower, 10 gasifier,
10a internal space, 11 storage thermal decomposition part, 11a internal space of storage thermal decomposition part,
11b Flange, 12 cylindrical combustion part, 12a Internal space of cylindrical combustion part,
13 ash reservoir, 13a internal space of ash reservoir, 13b outlet,
14 screw conveyor, 15 heat exchanger, 15a recess, 15b heat-resistant metal,
15c annular space, 16 communication pipes, 17 communication pipes, 18 upper cover,
19 Fuel supply part, 19a Steel pipe, 19b Upper gate, 19c Lower gate,
20 upper air supply pipe, 21 upper air amount adjustment valve, 22 gas supply pipe,
23 gas amount adjusting valve, 24 lower air introduction part, 24a lower air introduction pipe,

Claims (6)

A gasification furnace that generates a combustible gas by reducing a fuel containing a component that is supplied to an internal space and becomes tar while limiting the amount of air in a reducing layer in the internal space,
A pyrolysis layer that is connected to the oxide layer in the internal space, stores the fuel before being burned in the oxide layer, and is heated and pyrolyzed in a state in which no air is supplied. Have
Gas supply unit and air for supplying combustion gas and air for thermally decomposing the heated fuel at a temperature lower than combustion in the oxide layer to a region on the oxide layer side in the pyrolysis layer With a supply section,
A gasification furnace characterized in that air is supplied from the air supply unit while the amount of air is limited. The gasifier according to claim 1, wherein the fuel stored in the pyrolysis layer is heated by heat from which the fuel previously supplied to the oxide layer is combusted. The heat exchanger which heat-exchanges between the said fuel stored by the said thermal decomposition layer, and the said fuel gas produced | generated by the reduction | restoration in the said reduction | restoration layer is provided. Gasifier. The gasification furnace according to any one of claims 1 to 3, wherein the combustion gas is a part of the fuel gas generated by reduction in the reduction layer. The gasification furnace according to any one of claims 1 to 4, further comprising a lock hopper type fuel supply unit that communicates with the internal space and supplies the fuel. The gasifier according to any one of claims 1 to 5, wherein the fuel is woody biomass.

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