JP2010229208A - Apparatus and method for gasification of biomass - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an apparatus and a process for gasification of a biomass preventing aggregation of a biomass in a gasification furnace, forming a homogeneous gas flow, and enabling stabilized gasification. <P>SOLUTION: The apparatus includes a biomass supplier 2 which supplies a granulated or molded biomass to a gasification furnace 1; a gasification agent supplier 5 which supplies a gasification agent into the gasification furnace; a device for detecting the position of a moisture layer 6 which detects the height position of an upper surface of a moisture layer at the top of a biomass-packed layer, which is formed by deposition of the granulated or molded biomass in the gasification furnace wherein, water condensation occurs; and a device for controlling the position of the moisture layer 7 which controls at least either of conditions for supplying a granulated or molded biomass to be supplied by the biomass supplier and conditions for supplying a gasification agent including an amount of the gasification agent to be supplied and a compositional ratio of the gasification agent, based on the detected signal indicating the height position of the upper surface of the moisture layer detected by the device for detecting the position of the moisture layer so that the height position of the upper surface of the moisture layer falls within a predetermined range. <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

  The present invention relates to a biomass gasification apparatus and a gasification method for generating gas from biomass in a gasification furnace.

  Non-Patent Document 1 discloses a gasification furnace that gasifies woody biomass derived from forest resources such as wood scrap, bark, and wood scraps and supplies generated gas as fuel for a gas engine, for example. In this gasification furnace, biomass is supplied from the upper part of the gasification furnace, and a packed bed in which biomass is deposited is formed in the furnace. This packed bed forms a wet layer, a dry region, a thermal decomposition region, a reduction region, and an oxidation region from the upper part, and the biomass descends from the upper part of the packed bed to the lower part as the gasification reaction proceeds. Steam and air are supplied as gasification agents from the lower part of the furnace, the gas flow in the furnace flows from the lower part of the furnace to the upper part of the furnace, and the generated gas is taken out from the discharge port in the upper part of the furnace.

The biomass supplied from the upper part of the gasification furnace contains about 30 to 55% of moisture in the case of wood mills, bark, wood chips, etc., so the wet layer formed at the top of the packed bed is moisture. High concentration. The biomass descending from the wet layer is dried by the heat of the generated gas to form a dry region. Biomass descending from the drying zone is pyrolyzed in the pyrolysis zone, producing flammable gases such as CH ₄ , CO, H ₂ , CO ₂ , H ₂ O, gaseous and mist-like tar, and fixed carbon. The combustible gas and the gas of CO ₂ , H ₂ O, gaseous and mist tars rise, and the fixed carbon falls. The fixed carbon descending from the pyrolysis region gasifies with water vapor in the reduction region to produce CO and H ₂ . In the oxidation area below the reduction area, the remaining fixed carbon, tar, and unpyrolyzed biomass are partially oxidized and burned, generating heat necessary for gasification, pyrolysis, and drying, and the combustion gas rises with heat. . Combustion ash is discharged from the bottom of the packed bed.

JFE Engineering Company Catalog (Cat. No. CA3047) “JFE-Felt-type woody biomass gasification power generation system” issued by JFE Engineering Corporation, 2004

  When the wood chip is gasified as biomass by the biomass gasification device described in Non-Patent Document 1, the size of the wood chip is 20-30 mm or more in width and length, and 10 mm or more in thickness. The wood chip of the shape is supplied to the gasification furnace, and there is an appropriate gap between the chips of the packed bed formed in the furnace, and the gas resistance in the packed bed and the ventilation resistance of the generated gas (packed bed) The pressure loss) is low, and the gas flow in the packed bed is uniform. As a result, the gasifying agent is sufficiently supplied to the biomass packed bed, thermal decomposition and gasification are satisfactorily performed, the generated gas is stably raised in the packed bed, and stable gasification is realized.

  However, for example, when powdery biomass such as sawdust, paper sludge, dried sewage sludge, rice husk, food residue, etc. is supplied to the gasifier and gasified as biomass, this powdered biomass is used. If supplied as it is, the packed bed of fine powdery biomass formed in the furnace does not have a void and a good ventilation path cannot be secured, so the ventilation resistance increases, the gas flow drifts, and the ventilation resistance is relatively small. A blow-through in which gas concentrates at the location occurs, and a uniform gas flow in the packed bed is not formed, making it difficult to perform stable gasification. Therefore, by granulating or molding powdery biomass into a granulated product or molded product, it is supplied to the gasification furnace as a predetermined size, thereby suppressing an increase in ventilation resistance in the packed bed. In addition, a uniform gas flow is formed to achieve stable gasification.

  On the other hand, a wet layer in which biomass having a high moisture concentration prior to drying is deposited is formed at the uppermost part of the packed bed. In the wet layer, the temperature of the biomass is 100 ° C. or lower. Water vapor generated by thermal decomposition and gasification is condensed and water is generated. Even if the biomass granulated product or biomass molded product obtained by granulating or molding powdered biomass is supplied to the gasification furnace, the wet layer has a high position in the furnace height direction and the wet layer is thick. In the wet layer, the biomass granulated product or biomass molded product absorbs condensed water and swells, and as a result, the granulated product or molded product adheres to each other to form a nodule. When a nodule is formed in the wet layer, the gap formed between the granulated products or the molded products is closed, and the ventilation resistance is increased, and a uniform gas flow in the packed layer is formed. This makes it difficult to perform stable gasification. Furthermore, it is difficult for the nodules to descend in the packed bed, causing clogging and causing problems in the operation of the gasifier.

  The present invention has been made in view of such circumstances, and even when a biomass granulated product or biomass molded product obtained by granulating or molding powdery biomass is supplied to a gasification furnace, biomass production is performed in a wet layer. A biomass gasification apparatus capable of preventing the granules or biomass molding from adhering to each other to form a nodule, forming a uniform gas flow in the packed bed, and performing stable gasification, and It is an object to provide a gasification method.

  In the present invention, the above-described problems are solved by a biomass gasification apparatus and gasification method having the following configuration.

<Biomass gasifier>
The present invention relates to a biomass gasification apparatus, a biomass supply apparatus for supplying a biomass granulated product or a biomass molded product to a gasification furnace, a gasification agent supply apparatus for supplying a gasification agent to a gasification furnace, and a gas Wet layer position detection device for detecting the upper surface height position of the wet layer in which moisture condensation is formed on the upper part of the biomass packed bed formed by depositing the biomass granulated product or biomass molded product in the conversion furnace, and the wet layer Based on the detection signal indicating the upper surface height position of the wet layer detected by the position detection device, the biomass granulated product or biomass molded product supplied by the biomass supply device so that the upper surface height position of the wet layer is within a predetermined range. It has a wet layer position control device for controlling at least one of supply conditions and gasification agent supply conditions including a gasification agent supply amount and a composition ratio of the gasification agent. .

  A packed bed in which the wet layer formed above the packed bed has an allowable layer thickness for the given biomass supply conditions, that is, the properties and shape of the granulated or molded product, the estimated moisture content, and the biomass supply amount The range of the height position, in other words, the range of the upper surface height position of the wet layer is determined in advance as a predetermined range, and the upper surface height of the wet layer is measured on the biomass supplied under the above conditions during gasification. Then, this is controlled to be within the predetermined range. The height of the upper surface of the biomass varies depending on the gasifying agent supply conditions such as the gasifying agent supply amount and the composition ratio of the gasifying agent even if the above conditions are the same. This can be done by adjusting. This means that the upper surface height position of the wet layer can be set within a predetermined range under the biomass supply conditions by adjusting the biomass supply conditions, particularly the biomass supply amount, without changing the gasifying agent supply conditions. Means you can. Furthermore, the wet layer upper surface height position can be kept within the predetermined range by simultaneously adjusting both the biomass supply condition and the gasifying agent supply condition.

  In the present invention, the wet layer position detection device can be configured as a plurality of pressure gauges provided on the inner wall of the gasification furnace and measuring the pressure in the gasification furnace at a plurality of positions in the height direction. The furnace pressure is greatly different between the wet layer forming the upper part of the biomass packed bed and the furnace space above the upper surface of the wet layer. For example, the pressure in the furnace space above the wet layer is lower than that of the wet layer. Therefore, if the furnace pressure is measured at a plurality of positions in the height direction, the height position at which the furnace pressure changes is the upper surface height position of the wet layer.

  In the present invention, the wet layer position detection device can be configured as a sounding device that measures the upper surface height position of the wet layer by a chain and a weight suspended from the top of the gasification furnace.

<Biomass gasification method>
The present invention relates to a biomass gasification method, wherein the upper surface height position of the wet layer in which moisture condensation occurs in the upper part of the biomass packed bed formed by depositing the biomass granulated product or biomass molded product in the gasification furnace And the supply conditions of the biomass granulated product or biomass molded product to be supplied to the gasification furnace, the supply amount of the gasifying agent and the gasifying agent so that the upper surface height position of the detected wet layer falls within a predetermined range. It is characterized by controlling at least one of the gasifying agent supply conditions including the composition ratio.

  In the present invention, the upper surface height position of the wet layer can be detected by measuring the pressure in the gasification furnace at a plurality of positions in the height direction with a plurality of pressure gauges provided on the inner wall of the gasification furnace.

  In the present invention, the upper surface height position of the wet layer can be detected by a sounding device that measures the upper surface height position of the wet layer with a chain and a weight suspended from the top of the gasification furnace.

  According to the present invention, even if a biomass granulated product or biomass molded product obtained by granulating or molding powdery biomass is supplied to the gasification furnace, the upper surface of the wet layer is kept within an allowable range. Since the height falls within a predetermined range, it is possible to prevent the biomass granulated product or biomass molded product from adhering to each other in the wet layer to form a conglomerate, and form a uniform gas flow in the packed bed, A biomass gasification apparatus and a biomass gasification method capable of performing stable gasification can be provided.

It is a schematic block diagram of the apparatus of one Embodiment of this invention.

  Hereinafter, an apparatus according to an embodiment of the present invention will be described with reference to the accompanying drawings.

  In FIG. 1, the code | symbol 1 is a gasification furnace which thermally decomposes biomass and gasifies this. The gasification furnace 1 has a supply port 1A for receiving biomass from outside the furnace, an air supply port 1B for receiving a gasifying agent into a packed bed of biomass formed in the furnace, and an exhaust for discharging the generated gas from the upper part of the furnace. 1C. This gasifying agent is, for example, a mixture of air and water vapor. Further, the gasification furnace 1 is provided with a plurality of pressure gauges as detection elements for detecting the upper surface height position of the wet layer in the height direction in a range covering the expected height of the wet layer of biomass. ing.

  A biomass supply device 2 is connected to the gasification furnace 1, and the biomass supply device 2 receives the biomass from the biomass granulation device or the molding device 4 via the storage tank 3. The granulating device or the forming device 4 receives the powdered or finely crushed biomass and converts it into a predetermined size of granulated biomass or shaped biomass (hereinafter simply referred to as “biomass”). After the biomass is stored in the storage tank 3, an appropriate amount is cut out from the storage tank 3 by a cutting device such as a rotary feeder and brought to the biomass supply apparatus 2. The biomass is obtained, for example, by granulating or molding powdery biomass such as sawdust, papermaking sludge, dried sewage sludge, rice husk, food residue, etc. with a granulator or molding device 4.

  The biomass supply device 2 is connected to the supply port 1A of the gasification furnace 1 by a conveying device such as a conveyor or a screw feeder, and the biomass is fed from the supply port 1A into the furnace by the screw feeder of the biomass supply device 2 or the like. Drop supplied. The supply amount is controlled, for example, by adjusting the number of revolutions of the screw feeder or turning on / off the operation.

  A gasifying agent supply device 5 is connected to the air supply port 1B in the lower part of the gasification furnace 1. The gasifying agent supply device 5 is a device for supplying a gasifying agent composed of air and water vapor to an air supply port 1B provided at the lower portion of the gasification furnace 1, and is a blower (not shown) that takes in air from outside and blows air. 1), a water vapor generator (not shown) that heats water to generate water vapor, and a mixer (not shown) that mixes air and water vapor. In the gasifying agent supply device 5, at least one of adjusting the air supply amount supplied to the mixer by adjusting the blower air flow rate and adjusting the water vapor generation amount of the water vapor generator is performed. Thus, the gasifying agent supply amount or the gasifying agent composition ratio is controlled. Further, the supply amount of the gasifying agent is adjusted and controlled as required by a flow rate adjusting damper provided in a flow path for feeding the gasifying agent from the mixer to the gasification furnace.

  In the region where the temperature of the biomass packed bed is 100 ° C or lower, water vapor generated by thermal decomposition and gasification of the biomass is condensed to produce moisture, and the supplied biomass has not yet been dried, forming a wet layer. ing. A wet layer position detection device 6 is connected to the gasification furnace 1. The wet layer position detecting device 6 includes pressure gauges 6A as the above-described detection elements provided at a plurality of positions in a range covering the height of the wet layer expected in the height direction on the inner wall of the gasification furnace 1. And means for calculating the wet layer position, specifically, the upper surface height position of the wet layer from the distribution of the pressure in the detection furnace obtained from the plurality of pressure gauges.

  Pressure gauges 6A provided at a plurality of positions in the height direction on the inner wall of the gasification furnace 1 measure the pressure in the furnace at each position. Moreover, since the pressure of the biomass packed bed is higher than the pressure of the space above the wet bed, the wet bed position detecting device is obtained by measuring the furnace pressure at each position in the height direction of the inner wall of the gasification furnace 1. 6, the upper surface height position of the wet layer (the height of the upper surface of the wet layer from the furnace bottom) is determined from the height position where the pressure changes in the pressure distribution in the height direction. The measurement data of the upper surface height position of the wet layer is transmitted to the wet layer position control device 7.

  The wetting layer position control device 7 receives the measurement data of the upper surface height position of the wetting layer transmitted from the wetting layer position detection device 6 and compares it with a predetermined predetermined range of the upper surface height position of the wetting layer. A command signal is sent to at least one of the biomass supply device 2 and the gasifying agent supply device 5 so that the upper surface height position of the layer falls within a preferable predetermined range, and at least one of the biomass supply condition and the gasifying agent supply condition is controlled. To do.

  Here, the said predetermined range, biomass supply conditions, and gasifying agent supply conditions are demonstrated.

  Biomass supply conditions are the properties, shape, moisture content, and biomass supply of granulated or molded biomass. If the type and state of biomass to be supplied are specified, the biomass supply conditions are mainly biomass supply. It is determined by the biomass supply amount in the apparatus 2. Further, the gasifying agent supply conditions are the gasifying agent supply amount and the gasifying agent composition ratio in the gasifying agent supply device 5.

  Within the packed bed formed by supplying granulated or molded biomass into the gasification furnace 1, the biomass absorbs the surrounding water and swells until the biomass descends to the drying zone, increasing its volume. However, if adjacent biomass (granulated product or molded product) adheres and binds to form a nodule, the ventilation resistance increases and a problem arises. It is desired to descend to the drying area in a short time. Therefore, it is preferable that the thickness of the wet layer in which the biomass stays until it reaches the dry region after being supplied into the furnace is smaller. Practical control of the thickness of the wet layer is possible and desirable by controlling the upper surface height position of the wet layer. A preferable predetermined range of the upper surface height position of the wet layer is determined in advance based on the biomass supply conditions, and the biomass supply conditions (in many cases, the biomass supply amount are set so that the upper surface height position of the wet layer is within the preferable predetermined range. ) And adjusting the gasifying agent supply conditions.

  This control reduces the biomass supply amount as a biomass supply condition and increases the gasifier supply amount as a gasification agent supply condition when the upper surface height position of the wet layer is above the upper limit position of the predetermined range. Or it is made by performing at least one of the increase of the air ratio of a gasification agent composition ratio.

  On the other hand, when the upper surface height position of the wet layer is below the lower limit position of the predetermined range, the biomass supply amount as the biomass supply condition is increased, and the gasification agent supply amount as the gasification agent supply condition is increased. This is done by at least one of reducing or reducing the air ratio of the gasifying agent composition ratio.

  By performing such control, the thermal decomposition and gasification of the biomass in the gasification furnace is activated, the uppermost position of the packed bed of biomass is lowered, and the upper surface height position of the wet layer is set within a preferable predetermined range. In other words, under such control, the supply of biomass that was scarce was increased, the speed of biomass supply, pyrolysis and gasification of the biomass was synchronized, and the uppermost position of the packed bed of biomass was raised. The upper surface height position of the wet layer is set to a preferable predetermined range.

  Next, how the biomass in the apparatus of this embodiment is gasified will be described.

  (1) First, biomass is granulated or molded to a predetermined size by a granulator or a molding device 4.

  (2) The granulated or molded biomass is stored in the storage tank 3, cut out from the storage tank 3, and sent to the biomass supply device 2.

  (3) Based on the command signal from the wet layer position control device 7, the biomass supply device 2 supplies biomass from the supply port 1A of the gasification furnace 1 by the amount commanded by the transport device. The supply amount is controlled, for example, by adjusting the screw feeder rotation speed.

  (4) On the other hand, the gasifying agent supply device 5 also receives a command signal from the wet layer position control device 7. Based on this command signal, the supply amount of the gasifying agent composed of air and water vapor and the amount of air and water vapor The gasification agent is supplied to the gas supply port 1B of the gasification furnace 1 by adjusting the quantity ratio.

  (5) A packed bed of the biomass is formed in the gasification furnace 1 that has been supplied with the granulated or molded biomass from the biomass supply device 2. In this packed bed, air and water vapor as gasifying agents received from the air inlet 1B rise between the biomass particles in the packed bed, and the upper layer of the packed bed is used as a wet layer. Biomass descends sequentially from the wet layer to the dry region, pyrolysis region, reduction region, and oxidation region, and during that time, as described above, product gas is generated, and the product gas rises in the furnace and exhausts. It is taken out from the mouth 1C.

  (6) The wet layer position detection device 6 detects the pressure in the furnace with the plurality of pressure gauges 6A, and obtains the pressure distribution in the furnace in the height direction. The pressure in the space above the packed bed is lower than the pressure in the packed bed. Therefore, in the wet layer position detection device 6, the height position where the furnace pressure distribution in the height direction changes is determined as the upper surface height position of the wet layer, and the signal is transmitted to the wet layer position control device 7.

  (7) Upon receiving a signal corresponding to the upper surface height position of the wet layer, the wet layer position control device 7 receives the biomass supply condition and the biomass surface condition so that the detected upper surface height position of the wet layer falls within a predetermined range. A command signal is transmitted to the biomass supply device 2 and the gasification agent supply device 5 so as to change the gasification agent supply conditions. This command signal is based on the data stored in advance, how much the biomass supply amount from the biomass supply device 2 should be set, how much the gasification agent supply amount and composition ratio from the gasification agent supply device 5 should be set Is sent to the biomass supply device 2 and the gasifying agent supply device 5 to control these devices.

  (8) The biomass supplied to the gasification furnace 1 from the biomass supply device 2 controlled in this way is gasified by the gasifying agent received from the gasifying agent supply device 5 also controlled. When controlled in this way, even if biomass obtained by granulating or forming powdery biomass is supplied to the gasification furnace, it is prevented that the biomass adheres to each other in the wet layer to form a nodule. A uniform gas flow is formed in the packed bed, and stable gasification is performed.

  In the embodiment described above, the biomass supply amount as the biomass supply condition and the gasification agent supply amount or the gasification agent composition ratio as the gasification agent supply condition so that the upper surface height position of the wet layer falls within a preferable predetermined range. However, when the operation is performed with the amount of heat generated from the gasification furnace, that is, the amount of generated gas set, the gasifying agent supply condition is set to a condition corresponding to the set gas amount, Biomass supply conditions are controlled so that the upper surface height position falls within a preferable predetermined range.

    The present invention can be used in the industrial field where fuel gas is generated from biomass.

DESCRIPTION OF SYMBOLS 1 Gasification furnace 2 Biomass supply apparatus 5 Gasifying agent supply apparatus 6 Wet layer position detection apparatus 7 Wet layer position control apparatus

Claims (6)

In a gasification apparatus that obtains a product gas by pyrolyzing a biomass granulated product or biomass molded product obtained by granulating or molding powdered biomass in a gasification furnace,
A biomass supply device for supplying a biomass granulated product or biomass molded product to a gasifier;
A gasifying agent supply device for supplying a gasifying agent to the gasification furnace;
A wet layer position detecting device for detecting the upper surface height position of the wet layer in which moisture condensation occurs in the upper part of the biomass packed bed formed by depositing the biomass granulated product or biomass molded product in the gasification furnace;
Based on the detection signal indicating the upper surface height position of the wet layer detected by the wet layer position detection device, the biomass granulated material or biomass molding supplied by the biomass supply device so that the upper surface height position of the wet layer is within a predetermined range. A biomass gasification apparatus comprising: a wet layer position control device that controls at least one of a supply condition of a product and a gasification agent supply condition including a gasification agent supply amount and a composition ratio of the gasification agent .   The biomass gasification device according to claim 1, wherein the wet layer position detection device has a plurality of pressure gauges provided on the inner wall of the gasification furnace and measuring the pressure in the gasification furnace at a plurality of positions in the height direction. .   2. The biomass gasification apparatus according to claim 1, wherein the wet layer position detection device includes a sounding device that measures the height position of the upper surface of the wet layer using a chain and a weight suspended from the top of the gasification furnace. In a gasification method of obtaining a product gas by thermally decomposing a biomass granulated product or a biomass molded product obtained by granulating or molding a powdery biomass by receiving a gasifying agent in a gasification furnace,
Detecting the upper surface height position of the wet layer where moisture condensation occurs in the upper part of the biomass packed bed formed by depositing the biomass granulated product or biomass molded product in the gasification furnace,
Including the supply conditions of the biomass granulated product or biomass molded product to be supplied to the gasification furnace, the supply amount of the gasifying agent, and the composition ratio of the gasifying agent so that the detected upper surface height position of the wet layer falls within a predetermined range A method for gasifying biomass, comprising controlling at least one of gasification agent supply conditions.   5. The upper surface height position of the wet layer is detected by measuring the pressure in the gasification furnace at a plurality of positions in the height direction with a plurality of pressure gauges provided on the inner wall of the gasification furnace. Gasification method for biomass.   The biomass gasification according to claim 4, wherein the upper surface height position of the wet layer is detected by a sounding device that measures the upper surface height position of the wet layer with a chain and a weight suspended from the top of the gasification furnace. Method.

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