JP6668283B2 - Gasifier - Google Patents

Description

  The present invention relates to a gasification apparatus provided with a gasification furnace that generates a gas by thermally decomposing a raw material.

  Conventionally, a gasifier for gasifying a raw material (typically, biomass) has been known. As such a gasifier, for example, there is a fixed-bed downdraft gasifier which has a simple furnace structure and is generally said to generate less tar.

  In a general fixed-bed down-draft gasifier, biomass as a raw material charged into a gasifier reacts in the order of pyrolysis, oxidation, and reduction, and generates gas in the process. The carbide (char) generated in the course of these reactions accumulates in the lower part of the gasification furnace, but after a certain period of time, the accumulated char is discharged to the outside of the gasification furnace by the discharge device.

  In the gasifier as described above, in recent years, it has been considered that unnecessary substances may be generated if the time that the char stays in the gasifier is too long. On the other hand, since the char also contributes to the generation of gas, there is a concern that if the time that the char stays in the char deposition region of the gasification furnace is too short, the gasification efficiency is reduced. Therefore, it is desirable that the time that the char stays in the char deposition region of the gasifier be adjusted to an appropriate length, and for that purpose, the upper surface of the char deposition region in the gasifier (that is, the char deposition layer) is formed. It is considered necessary to keep the position of (upper surface) near the target height.

  However, control for keeping the upper surface of the char deposition layer in the gasifier near the target height has not been easy in the past.

  As a means for keeping the upper surface of the deposited layer of the char in the gasifier near the target height, for example, as described in Patent Document 1, it is considered to adjust the amount of the raw material charged into the gasifier. Can be However, even if the input amount of the raw material is appropriately adjusted, the amount of the char deposited in the char deposition region greatly varies depending on the progress of the thermal decomposition and the partial combustion of the raw material in the gasification furnace. It was difficult to sufficiently control the height of the upper surface of the deposited layer.

  As another means for keeping the upper surface of the deposited layer of the char in the gasification furnace near the target height, for example, as described in Patent Document 2, the driving state (motor) of a discharge device (rotary extractor) It is conceivable to control the number of revolutions). However, Patent Document 2 mainly aims to continuously obtain a temperature (peak temperature) of a combustion zone that needs to be monitored in order to improve gasification efficiency in a moving bed type gasifier, It merely discloses control for appropriately stopping and starting the extraction of the char in order to constantly and vertically fluctuate the position of the combustion zone in the furnace height direction range where the temperature sensor group is provided. That is, even with reference to the control disclosed in Patent Literature 2, the upper surface of the deposited layer of the char in the gasification furnace cannot be kept near the target height.

JP 2013-139528 A JP 2005-139338 A

  The present invention has been made in view of the above circumstances, and an object of the present invention is to realize control for keeping the upper surface of a deposited layer of carbide in a gasification furnace in the vicinity of a target height.

Means and effects for solving the problem

  The problem to be solved by the present invention is as described above. Next, means for solving the problem and its effects will be described.

According to an aspect of the present invention, a gasifier having the following configuration is provided. That is, this gasification device includes a gasification furnace, a discharge device, a detection unit, and a control device. The gasification furnace thermally decomposes a raw material to generate a gas, and deposits carbide generated in the process. The discharge device discharges the deposited carbide outside the gasification furnace. The detector detects a height of an upper surface of the carbide deposition layer. The control device is configured to determine a difference between a current height of the upper surface of the carbide deposition layer obtained from the detection result of the detection unit and a target deposition height that is a predetermined target height of the upper surface of the carbide deposition layer. The control for changing the discharge speed of the discharge device from the current discharge speed based on the above is repeatedly performed. The detection unit has a first temperature sensor and a second temperature sensor. The second temperature sensor is disposed below the first temperature sensor in a furnace height direction of the gasification furnace. When the difference between the detection value of the first temperature sensor and the detection value of the second temperature sensor is equal to or greater than a threshold value, the upper surface of the deposited layer of the carbide has the first temperature in the furnace height direction of the gasification furnace. It is determined that it is located between the sensor and the second temperature sensor.

  Here, with respect to the discharge speed of the discharge device, the optimum value that makes the height of the upper surface of the carbide deposition layer appropriate is different depending on the size of the gasification furnace, the type and state of the raw material, and the like. Therefore, if the optimal discharge speed is determined in advance and the discharge device is to be controlled, it is necessary to individually examine the optimal discharge speed in accordance with various assumed conditions, which is not practical. In this regard, in the present configuration, in the present configuration, the process of changing the current discharge speed of the discharge device based on the difference between the current height of the upper surface of the carbide deposition layer and the target deposition height is repeated, thereby obtaining the carbide deposition layer. Can be controlled so that the height of the upper surface of the substrate approaches an appropriate state. As a result, it is possible to flexibly realize control for bringing the height of the upper surface of the carbide deposition layer closer to an appropriate state.

  In the gasification device, the control device may include an increase width set according to a difference between the current height of the upper surface of the deposited layer of the carbide obtained by the detection result of the detection unit and the target deposition height, or It is preferable to change the discharge speed with the width of decrease.

  This makes it possible to vary the raising or lowering width when changing the discharge speed of the discharge device according to the difference between the current height of the upper surface of the carbide deposition layer and the target deposition height. Therefore, the height of the upper surface of the carbide deposition layer can be finely controlled.

  In the gasifier, the following configuration is preferable. That is, the gasifier includes a storage unit that stores a correction value for changing a discharge speed of the discharge device. The storage unit stores a plurality of different correction values selected according to the degree of deviation between the current height of the upper surface of the carbide deposition layer obtained from the detection result of the detection unit and the target deposition height. I do.

  This makes it possible to change the discharge speed of the discharge device by applying a correction value according to the degree of deviation between the current height of the upper surface of the carbide deposition layer and the target deposition height. As a result, control for bringing the height of the upper surface of the carbide deposited layer closer to an appropriate state can be easily realized.

FIG. 1 is a schematic diagram illustrating an overall configuration of a gasifier according to an embodiment of the present invention. The schematic diagram explaining the gasification furnace with which the gasification apparatus is provided, and the structure related to it. FIG. 3A is a conceptual diagram illustrating a positional relationship between a temperature sensor and a target deposition height of a char in a gasification furnace. FIG. 4B is a diagram illustrating an example of a plurality of correction values stored in a storage unit with respect to the motor frequency control of the char discharger. 9 is a flowchart showing a process performed by the control device to make the height of the upper surface of the deposition layer of the char closer to a more appropriate state.

  Next, an embodiment of the present invention will be described with reference to the drawings. FIG. 1 is a schematic diagram illustrating an overall configuration of a gasifier 1 according to an embodiment of the present invention. FIG. 2 is a schematic diagram illustrating a gasification furnace 2 provided in the gasification apparatus 1 and a configuration related thereto. FIG. 3A is a conceptual diagram illustrating a positional relationship between a temperature sensor in the gasification furnace 2 and a target deposition height of char. FIG. 3B is a diagram illustrating an example of a plurality of correction values stored in the storage unit with respect to the motor frequency control of the char discharging device 4.

  First, the overall configuration of the gasifier 1 according to the present embodiment will be described with reference to FIG.

  The gasifier 1 of the present embodiment is an organic resource of biological origin such as rice husk or wood-based waste material (strictly speaking, it is an organic resource excluding fossil resources and may be referred to as “biomass”). ) Is used as a fuel (raw material, gasification target) to generate gas, and power is generated using the gas. As shown in FIG. 1, a gasifier 1 of the present embodiment includes a gasifier 2, a fuel supply device 3, a char discharge device 4, a bag filter 5, a gas cooling device 6, a cleaning device 7, an induction blower 8, The apparatus includes a device 9, a cogeneration system 10, a surplus gas combustion device 11, and the like.

  The gasification furnace 2 shown in FIG. 2 is a furnace in which a main reaction of gasification of a raw material is performed. The gasification furnace 2 of the present embodiment is a so-called fixed-bed furnace. As shown in FIG. 2, an oxidizing agent supply port 13 for supplying air or oxygen as an oxidizing agent to the inside of the gasifying furnace 2 is provided at an intermediate portion in the vertical direction of the gasifying furnace 2.

  As schematically shown in FIG. 2, a region in which the raw material is thermally decomposed and oxidized (partial combustion) is formed inside the gasification furnace 2. Further, a char accumulation region in which the char remaining after the thermal decomposition and the partial combustion is accumulated is formed below the region where the partial combustion is performed inside the gasification furnace 2. The oxidizing agent supply port 13 is provided in a hole shape at a position corresponding to the region where the partial combustion is performed in the furnace height direction of the gasification furnace 2 so as to communicate the inside and the outside of the gasification furnace 2.

  The fuel supply device 3 supplies a raw material into the gasifier 2 from the upper end thereof. The fuel supply device 3 of the present embodiment includes a hopper 31, a screw 32, a motor, and the like. The hopper 31 is a container into which raw materials are charged. The screw 32 is rotatably attached to the bottom of the hopper 31. The motor is configured, for example, as an AC motor, and drives the screw 32 to rotate. In the present embodiment, the screw 32 is driven to rotate at a constant speed by an alternating current having a constant frequency flowing through the motor. As a result, the raw material is introduced into the gasification furnace 2 in an amount corresponding to the rotation speed of the screw 32. However, the motor is not particularly limited to an AC motor.

  The char discharging device 4 discharges (extracts) the char remaining after gasification (reduction) from the bottom of the char deposition area in the gasification furnace 2. More specifically, the char discharger 4 includes, for example, a rotary valve 41 and a screw conveyor 42. The rotary valve 41 is driven to rotate, thereby supplying the char extracted from the extraction hole provided at the bottom of the gasification furnace 2 to the screw conveyor 42 below. The screw conveyor 42 conveys the extracted char to a predetermined place outside the gasification furnace 2 by being rotationally driven.

  In the present embodiment, an output shaft of a motor is connected to the rotary valve 41 and the screw conveyor 42, respectively. This motor may be a DC motor or an AC motor. In the case of an AC motor, the motor rotates at a speed corresponding to the frequency of the supplied AC current, and accordingly, the rotary valve 41 and the screw conveyor 42 perform a discharging operation (specifically, rotation). . Therefore, the frequency of the alternating current supplied to the AC motor is appropriately changed by the inverter, so that the substantial amount of extraction (discharge speed) of the char per unit time can be increased or decreased. This makes it possible to adjust the level (deposition amount) at which the char is deposited in the gasification furnace 2 so as to be substantially constant.

In a region above the char deposition region in the gasification furnace 2, the raw material supplied from the fuel supply device 3 is dried. The dried raw material is then pyrolyzed by burning in an oxygen-deficient state. Thus, about 50-90% of the raw material gas _{(CO, H 2, CH 4} , CO 2, H 2 O) to and gaseous substances such as tar, fixed carbon which about 10-50% remaining called char Is converted to The rate of conversion fluctuates under the influence of the heating rate in the furnace, the type and particle size of the raw materials, and the like. The thermal decomposition product generated by the thermal decomposition is oxidized (partially burned) by the air or oxygen supplied from the oxidant supply port 13. The heat generated by this partial combustion is used as a heat source in the above-mentioned thermal decomposition. The char remaining after the partial combustion is deposited in a char accumulation region below the region where the partial combustion is performed.

In the char deposition region in the gasification furnace 2, a reduction reaction by the char is performed at a temperature substantially lower than that in the partial combustion, whereby the char is brought into a steamed state and gasified. In the gasification (reduction) by the char in the char deposition region, CO and H ₂ are generated.

  The gas generated in the gasification furnace 2 is supplied to a cogeneration system 10 and a surplus gas combustion device 11 through a gas path constituted by pipes and the like as shown in FIG. In the middle of the gas path between the gasification furnace 2 and the cogeneration system 10 (excess gas combustion device 11), a bag filter 5, a gas cooling device 6, and a cleaning device 7 are arranged from upstream to downstream. , And the induction blower 8 are arranged in this order.

  The bag filter 5 is for removing carbon fine particles such as soot, dust and the like contained in the gas flowing from the gasification furnace 2. The bag filter 5 passes gas through the filter of the bag filter 5 using a method such as trapping and adsorption, and removes soot, dust, and the like with the filter.

  The gas cooling device 6 cools the gas flowing after passing through the bag filter 5 and increases the density of the gas. The gas cooling device 6 cools the gas using, for example, a method such as heat exchange. Specifically, the gas cooling device 6 includes, for example, a heat exchanger to which cooling water is supplied, and a gas path piped between the heat exchangers. Water from the water storage tank is supplied to the heat exchanger as cooling water, and heat exchange is performed between the cooling water and the gas.

  The cleaning device 7 is for cleaning gas flowing after cooling by the gas cooling device 6 to remove tar and the like. The cleaning device 7 removes tar by performing a physical process including, for example, a step of condensing a gaseous tar, a step of separating a gas-liquid mixture, and a step of performing droplet filtration.

  The induction blower 8 induces the gas from the gasification furnace 2 toward the cogeneration system 10 by generating a negative pressure. The induction blower 8 is composed of, for example, an induction-type blower. Due to the operation of the induction blower 8, a negative pressure is generated in the gas path and the gasification furnace 2 on the upstream side of the induction blower 8.

  The cogeneration system 10 includes a gas engine, a generator, and the like. The gas generated in the gasification furnace 2 is supplied to the gas engine after its density is increased by removing soot and tar and the like, and the heat energy of the gas is converted into rotary motion by the gas engine. This rotational motion is transmitted to the generator to generate electricity. Part of the heat energy of the gas is used for hot water supply and the like.

  Of the gas that has passed through the induction blower 8, the surplus gas that has not been supplied to the cogeneration system 10 is supplied to the surplus gas combustion device 11. The surplus gas combustion device 11 incinerates surplus gas, converts carbon monoxide to carbon dioxide, and renders it harmless.

  The control device 9 includes the gasifier 2, the fuel supply device 3, the char discharge device 4, the bag filter 5, the gas cooling device 6, the cleaning device 7, the induction blower 8, the cogeneration system 10, the surplus gas combustion device 11, and the like. It is a controller that controls. The control device 9 is configured as a computer including a CPU, a ROM, a RAM, and the like, and the CPU can read various programs and the like from the ROM and execute the programs. The ROM stores an appropriate program for causing the gasifier 1 to appropriately gasify the raw material. Then, the cooperation of the software and the hardware described above causes the gasifier 1 to appropriately gasify the raw material, remove soot and tar in the gas, concentrate the gas, the cogeneration system 10 and the surplus gas combustion device. For example, the supply of gas to 11 can be performed.

  The storage unit 12 is a memory that stores numerical values, parameters, and the like used for various controls performed by the control device 9. Specifically, the storage unit 12 stores a value of a target deposition height described later, a correction value, and the like.

  In the gasifier 1 configured as described above, gas is typically generated in the gasifier 2 using a raw material that is biomass as a fuel, and soot and tar contained in the gas are removed in the middle of the gas path. After being concentrated, the gas is supplied to the cogeneration system 10. Electric power can be obtained by the thermal energy of this gas. That is, energy that typically uses biomass as a raw material is converted into electric power and extracted. Thereby, the raw material as a renewable energy source can be effectively used.

  In recent years, it has been considered a problem that an unnecessary substance is generated when the time that the char stays in the char deposition region is too long. On the other hand, if the time that the char stays in the char deposition region is too short, sufficient gasification (oxidation) of the char may not be performed, and the gasification efficiency may be reduced. Therefore, it is desired that the char stays in the char deposition area for an appropriate time and then be discharged. To do so, the position of the upper surface of the char deposition area in the gasification furnace 2 (that is, the char deposition Level) should be kept close to the target height.

  Therefore, in the gasification apparatus 1 of the present embodiment, the char deposition layer (a layer in which most of the deposited material is occupied by char. Hereinafter, it may be simply referred to as a “char deposition layer”. ) Is controlled so that the height of the upper surface of the upper surface of the char deposition layer is kept near the target height (in other words, the ideal height) of the upper surface of the char deposition layer.

  Note that the target deposition height is variously set in advance as an ideal char deposition layer height such that the residence time of the char in the char deposition layer is an appropriate time that is neither too long nor too short. Is determined by the examination of This target deposition height is stored in the storage unit 12.

  Further, the gasification device 1 of the present embodiment includes a detection unit for detecting the height of the upper surface of the char deposition layer. The detection unit is, for example, a plurality of temperature sensors arranged in the height direction of the gasification furnace 2. Specifically, the gasifier 1 of the present embodiment includes a first temperature sensor T1, a second temperature sensor T2, a third temperature sensor T3, a fourth temperature sensor T4, a fifth temperature sensor T5, A sixth temperature sensor T6 is provided. These temperature sensors T1, T2... May be arranged at equal intervals in the furnace height direction, or may be arranged at unequal intervals. Each of these temperature sensors T1, T2,... Is electrically connected to the control device 9.

  As shown in FIG. 3A, the first temperature sensor T1 is provided at a position above the target deposition height by a first distance L1 in the furnace height direction of the gasification furnace 2. The first temperature sensor T <b> 1 of the present embodiment is disposed near the oxidant supply port 13 in the furnace height direction of the gasification furnace 2.

  The second temperature sensor T2 is provided at a position above the target deposition height in the furnace height direction of the gasification furnace 2 by a second distance L2 shorter than the first distance L1.

  The third temperature sensor T3 is provided at a position corresponding to the target deposition height. That is, in the present embodiment, the third distance L3 (not shown) between the third temperature sensor T3 and the target deposition height in the furnace height direction of the gasification furnace 2 is zero. However, the third distance L3 may be larger than 0 and smaller than the second distance L2.

  The fourth temperature sensor T4 is provided at a position below the target deposition height by a fourth distance L4 in the furnace height direction of the gasification furnace 2. The fourth distance L4 can be, for example, a distance equal to the second distance L2, but is not limited thereto.

  The fifth temperature sensor T5 is provided at a position below the target deposition height by a fifth distance L5 in the furnace height direction of the gasification furnace 2. The fifth distance L5 can be, for example, a distance equal to the first distance L1, but is not limited thereto.

  The sixth temperature sensor T6 is provided at a position lower by a sixth distance L6 longer than the fifth distance L5 in the furnace height direction of the gasifier 2 with respect to the target deposition height. The sixth temperature sensor T6 is provided at a position corresponding to a limit height, for example, where it is determined that if the height of the upper surface of the char deposition layer becomes lower than this, the reduction by the char becomes insufficient. .

  The specific values of the six distances L1, L2, ... depend on the size of the gasification furnace 2, but may be, for example, several tens of centimeters. Each of the first to sixth temperature sensors T1, T2,... Can detect the temperature in the gasification furnace 2 at the height at which the temperature sensor is provided.

  Although not shown, a plurality of first to sixth temperature sensors T1, T2,... Are provided, for example. Each of the plurality of temperature sensors T1, T2,... Is arranged along the circumferential direction of the gasification furnace 2. The average value of the detected values of the plurality of temperature sensors arranged in the circumferential direction is adopted as the detected value of each of the first to sixth temperature sensors T1, T2,. This is used for determining the height of the upper surface of the deposition layer. However, the value adopted as each detection value of the temperature sensors T1, T2,... Is not limited to the average value. For example, each median value of the temperature sensors T1, T2,. Can also be adopted.

  Here, the principle by which the detection unit of the present embodiment obtains the height of the upper surface of the char deposition layer will be briefly described.

  When the position corresponding to the temperature sensor in the furnace height direction of the gasification furnace 2 is buried with the deposited char, it is more evident than when it is not buried with the char (particularly, when it corresponds to the region where partial combustion is performed). , A much lower temperature should be detected. This is because the pyrolysis products are partially burned above the char deposition layer of the gasification furnace 2 and reach, for example, 1000 ° C. or higher, and the char deposition layer has a lower temperature (for example, 700 to 700 ° C.). This is because the reduction reaction by the char is performed at 1000 ° C.). The detection unit of the present embodiment obtains the approximate height of the upper surface of the char deposition layer by focusing on the characteristics of the temperature distribution in the furnace height direction in the gasification furnace 2.

  Specifically, the differences between the detected values (absolute temperatures) obtained by the temperature sensors adjacent to each other in the furnace height direction of the gasification furnace 2 are calculated, and the temperature sensor whose difference is equal to or larger than a threshold is specified. . Thereby, it can be grasped that the upper surface of the char deposition layer is at a position between the temperature sensors adjacent in the furnace height direction at which the temperature difference equal to or larger than the threshold is detected. For example, when the difference between the detection value of the second temperature sensor T2 and the detection value of the third temperature sensor T3 is equal to or larger than the threshold, the upper surface of the char deposition layer is located between the second temperature sensor T2 and the third temperature sensor T3. Can be determined.

  When there are a plurality of temperature sensors adjacent to each other in the furnace height direction of the gasification furnace 2 whose detected value difference is equal to or larger than a threshold value, the pair of temperature sensors having the largest detected value difference is specified. do it. That is, it is determined that the upper surface of the char deposition layer is located between the temperature sensors having a difference between the detection values equal to or larger than the threshold value and the maximum among the temperature sensors adjacent in the furnace height direction of the gasification furnace 2.

  The threshold used in obtaining the height of the upper surface of the char deposition layer is determined in consideration of a difference between the expected temperature of the char deposition layer and the expected temperature of the gas layer above the char deposition layer. Can be. Each expected temperature may be acquired in advance by, for example, a test operation or analysis of the gasifier 2. The threshold value can be set by, for example, selecting from the range of 100 to 600 ° C, more preferably 200 to 300 ° C.

  In order to control the position of the upper surface of the char deposition layer, the position of the upper surface of the char deposition layer in the furnace height direction deviates from the range where the first temperature sensor T1 to the sixth temperature sensor T6 are arranged. In addition, it is necessary to know at least whether the upper surface of the char deposition layer is located at a position higher than the first temperature sensor T1 or lower than the sixth temperature sensor T6.

  Therefore, in the present embodiment, when no temperature difference equal to or larger than the threshold is found in any of the temperature sensors adjacent in the furnace height direction, the temperature difference equal to or larger than the threshold is detected immediately before the first temperature sensor. It is checked by referring to the temperature difference acquired in the past whether it was between T1 and the second temperature sensor T2 or between the fifth temperature sensor T5 and the sixth temperature sensor T6.

  If the temperature difference equal to or larger than the threshold was detected immediately before the first temperature sensor T1 and the second temperature sensor T2, the position of the upper surface of the char deposition layer in the furnace height direction is shifted from the first temperature sensor T1 to the first temperature sensor T1. It is presumed that the upper surface of the char deposition layer was at a height between the first temperature sensor T1 and the second temperature sensor T2 immediately before the temperature deviated from the range in which the six temperature sensors T6 were disposed. Therefore, it can be understood that the current position of the upper surface of the char deposition layer in the furnace height direction is above the first temperature sensor T1.

  On the other hand, when the temperature difference equal to or larger than the threshold was detected immediately before the fifth temperature sensor T5 and the sixth temperature sensor T6, the position of the upper surface of the char deposition layer in the furnace height direction is changed to the first temperature sensor T1. It is presumed that the upper surface of the char deposition layer was at a height between the fifth temperature sensor T5 and the sixth temperature sensor T6 immediately before the position deviated from the range from the first temperature sensor to the sixth temperature sensor T6. Therefore, it can be understood that the current position of the upper surface of the char deposition layer in the furnace height direction is below the sixth temperature sensor T6.

  By performing the above-described determination, the control device 9 of the present embodiment, based on the values detected by the temperature sensors T1, T2,... You are getting the height.

  Next, a control flow performed in the gasifier 1 to maintain the height of the upper surface of the char deposition layer near the target deposition height will be described in detail mainly with reference to FIG. FIG. 4 is a flowchart illustrating a process performed by the control device 9 to make the height of the upper surface of the char deposition layer closer to a more appropriate state.

  First, the control device 9 acquires temperature detection values from the first to sixth temperature sensors T1, T2,... (Step S101).

  Subsequently, the control device 9 acquires the current approximate height of the upper surface of the char deposition layer in the gasification furnace 2 according to the above-described principle using the detected temperature value acquired in step S101. The control device 9 acquires the degree of the difference ΔH between the current height of the upper surface of the char deposition layer and the target deposition height (step S102). In this description, when the difference ΔH is a positive value, it means that the height of the upper surface of the char deposition layer is above the target deposition height, and when the difference ΔH is a negative value, it is below. Means that.

  More specifically, when it is determined that the current upper position of the upper surface of the char deposition layer in the furnace height direction is above the first temperature sensor T1, the control device 9 determines the height of the upper surface of the current upper surface of the char deposition layer. In other words, it is determined that the target deposition height deviates upward by a distance exceeding the first distance L1 (ΔH> L1).

  When it is determined that the position of the upper surface of the current char deposition layer in the furnace height direction is between the first temperature sensor T1 and the second temperature sensor T2, the controller 9 determines the height of the current upper surface of the char deposition layer. The height is determined to be greater than the second distance L2 with respect to the target deposition height and deviated upward by a distance equal to or less than the first distance L1 (L1 ≧ ΔH> L2).

  When it is determined that the position of the current upper surface of the char deposition layer in the furnace height direction is between the second temperature sensor T2 and the third temperature sensor T3, the control device 9 determines the height of the current upper surface of the char deposition layer. In other words, it is determined that the target deposition height is deviated upward by a distance equal to or less than the second distance L2 (L2 ≧ ΔH> 0).

  In the present embodiment, since the position of the third temperature sensor T3 in the furnace height direction matches the target deposition height (third distance L3 = 0), the control device 9 determines that the upper surface of the current char deposition layer is the second deposition height. If it is located between the temperature sensor T2 and the third temperature sensor T3, it is determined that L2 ≧ ΔH> 0. When the third temperature sensor T3 is disposed above or below the target deposition height (third distance L3 ≠ 0), the control device 9 determines that the upper surface of the current char deposition layer is the second temperature sensor T2 and the third temperature sensor T2. When located between the temperature sensor T3, it is determined that L2 ≧ ΔH> L3 or L2 ≧ ΔH> −L3.

  If it is determined that the position of the upper surface of the current char deposition layer in the furnace height direction is between the third temperature sensor T3 and the fourth temperature sensor T4, the controller 9 determines the height of the upper surface of the current char deposition layer. It is determined that the distance is lower than the target deposition height by a distance equal to or less than the fourth distance L4 (0 ≧ ΔH> −L4).

  When it is determined that the position of the upper surface of the current char deposition layer in the furnace height direction is between the fourth temperature sensor T4 and the fifth temperature sensor T5, the controller 9 determines the height of the upper surface of the current char deposition layer. The height is determined to be greater than the fourth distance L4 and lower than the fifth distance L5 below the target deposition height (−L4> ΔH ≧ −L5).

  When it is determined that the position of the upper surface of the current char deposition layer in the furnace height direction is between the fifth temperature sensor T5 and the sixth temperature sensor T6, the controller 9 determines the height of the upper surface of the current char deposition layer. It is determined that the distance is greater than the fifth distance L5 and lower than the sixth distance L6 below the target deposition height (−L5> ΔH ≧ −L6).

  When it is determined that the position of the upper surface of the current char deposition layer in the furnace height direction is below the sixth temperature sensor T6, the control device 9 determines that the height of the current upper surface of the char deposition layer is the target deposition height. On the other hand, it is determined that the distance deviates downward by a distance exceeding the sixth distance L6 (-L6> ΔH).

  As described above, in step S102, the control device 9 according to the present embodiment determines which of a plurality of levels corresponds to the degree of the deviation of the current height of the upper surface of the char deposition layer from the target deposition height. Acquire by judgment.

  The storage unit 12 obtains the plurality of correction values of the frequency of the AC current supplied to the AC motor included in the char discharge device 4 and obtains the target deposition height of the current height of the upper surface of the char deposition layer obtained in step S102. It is stored in association with the degree of deviation from that. In this embodiment, a plurality of ranges of ΔH (ΔH> L1, L1 ≧ ΔH> L2, L2 ≧ ΔH> 0, 0 ≧ ΔH> −L4, −L4> ΔH ≧ −L5, −L5> ΔH ≧ −L6, A plurality of correction values (+15, +10, +5, 0, -5, -10, and -15 [Hz]) are stored in the storage unit 12 in advance in accordance with (−L6> ΔH).

  After step S102, the control device 9 determines the deviation of the current deposition height obtained in step S102 from the target deposition height from among a plurality of correction values stored in advance in the storage unit 12 for the frequency of the alternating current. (Step S103). In addition, these correction values are examined by, for example, performing an experiment or analysis, etc. to determine the relative relationship between the degree of the deviation of the char deposition level from the target level and the degree to which the frequency of the motor should be changed. You can ask.

  In the present embodiment, as shown in FIG. 3B, the correction value is selectively selected according to the degree of deviation of the current char deposition level from the target level. For example, when the difference ΔH between the target deposition height and the current position of the upper surface of the char deposition layer is larger than L1 (ΔH> L1), +15 [Hz] is selected as the correction value. If the position of the upper surface of the char deposition layer is equal to or lower than the target deposition height and the difference ΔH is smaller than L4 (0 ≧ ΔH> −L4), the height of the upper surface of the char deposition layer becomes higher. Since it is considered appropriate at this time, 0 [Hz] is selected as the correction value.

  Subsequently, the control device 9 calculates a new frequency by adding the correction value selected in step S103 to the frequency of the AC current currently applied to the AC motor of the char discharging device 4 (step S104). .

  When the frequency is increased by the correction, the rotary valve 41 and the screw conveyor 42 rotate at a higher speed than at present, so that the amount of char withdrawn from the gasification furnace 2 increases, and the height of the upper surface of the char deposition layer increases. It becomes easy to descend. When the frequency is reduced by the correction, on the contrary, since the rotary valve 41 and the screw conveyor 42 rotate at a lower speed compared to the present, the amount of extraction of the char from the gasification furnace 2 is reduced, and the char accumulation layer is reduced. The height of the upper surface of the substrate easily rises.

  Subsequently, the control device 9 outputs an appropriate control signal to an inverter (not shown) so that the AC current having the corrected frequency calculated in step S104 is supplied to the AC motor of the char discharging device 4 (step S104). S105). Thereby, the rotation speed of the rotary valve 41 and the screw conveyor 42 is controlled such that the position of the upper surface of the char deposition layer approaches the target deposition height. As a result, the height of the upper surface of the deposited layer of the char can be brought close to an appropriate state.

  Thereafter, the process returns to step S101, and the control device 9 repeats the processing of steps S101 to S105.

  According to the above control, for example, when the situation where ΔH is greater than zero continues for a long time, the correction (change) for increasing the frequency of the alternating current is performed repeatedly, so that the discharging operation of the char discharging device 4 is performed. The speed will continue to increase, and ΔH will eventually approach zero. In this way, the speed of the discharging operation of the char discharging device 4 is appropriately adjusted.

  Further, as shown in FIG. 3 (b), the absolute value of the frequency correction value of the present embodiment is increased as the height of the upper surface of the char deposition layer deviates greatly from the target deposition height. Determined. Therefore, when the amount of deviation between the height of the upper surface of the char deposition layer and the target deposition height is large, the speed of the discharge operation of the char discharger 4 can be changed sharply, so that good responsiveness can be realized. it can.

  As described above, the gasifier 1 of the present embodiment includes a gasifier 2, a char discharger (discharger) 4, and first to sixth temperature sensors (detectors) T1, T2. .. And a control device 9. The gasification furnace 2 generates a gas by thermally decomposing a raw material, and the char generated in the process is deposited. The char discharging device 4 discharges the deposited char to the outside of the gasification furnace 2. The first to sixth temperature sensors T1, T2,... Detect the height of the upper surface of the char deposition layer. The controller 9 controls the current height of the upper surface of the char deposition layer obtained based on the detection results of the first to sixth temperature sensors T1, T2,... And a predetermined target of the upper surface of the char deposition layer. Control for changing the speed of the discharging operation of the char discharging device 4 from the current speed is repeatedly performed based on the difference between the target deposition height which is the height.

  Here, regarding the speed of the discharging operation of the char discharging device 4, an optimum value that makes the height of the upper surface of the char deposition layer appropriate is different depending on the size of the gasification furnace 2, the type and state of the raw material, and the like. . Therefore, if an attempt is made to control the char discharging device 4 by setting an optimal operation speed in advance, it is necessary to individually examine the optimal operation speed in accordance with various assumed conditions. Not. In this regard, in the present embodiment, the process of changing the current operating speed of the char discharger 4 based on the difference between the current height of the upper surface of the char deposition layer and the target deposition height is repeated, thereby The height of the upper surface of the deposition layer can be controlled so as to approach a proper state. That is, it is possible to flexibly realize control for bringing the height of the upper surface of the char deposition layer closer to an appropriate state without fixedly determining the operation speed of the char discharging device 4.

  Further, in the gasifier 1 of the present embodiment, the controller 9 controls the height of the upper surface of the current char deposition layer obtained based on the detection results of the first to sixth temperature sensors T1, T2,. The speed of the discharging operation is changed by an increase width or a decrease width set in accordance with the difference (degree of deviation) between the target and the target deposition height.

  This makes it possible to vary the raising width or the lowering width when changing the discharge operation speed according to the difference between the current upper surface height of the char deposition layer and the target deposition height. Therefore, the height of the upper surface of the char deposition layer can be finely controlled.

  In addition, the gasifier 1 of the present embodiment includes a storage unit 12 that stores a correction value for changing the speed of the discharging operation of the char discharging device 4. The storage unit 12 stores the current height of the upper surface of the char deposition layer obtained from the detection results of the first to sixth temperature sensors T1, T2,. A plurality of different correction values (in this embodiment, the seven correction values shown in FIG. 3B) that are selected and selected are stored.

  Thereby, a correction value (+15, +10, +5, 0, −5, −10, or −10 in the present embodiment) corresponding to the degree of deviation between the current upper surface height of the char deposition layer and the target deposition height. By applying 15), the operation speed of the char discharging device 4 can be changed. As a result, control for bringing the height of the upper surface of the char deposition layer closer to an appropriate state can be easily realized.

  Further, in the gasification apparatus 1 of the present embodiment, the detection unit is configured to include a plurality of temperature sensors T1, T2,... Provided side by side in the furnace height direction of the gasification furnace 2. When the difference (temperature difference) between the detection values of two temperature sensors (for example, the second temperature sensor T2 and the third temperature sensor T3) adjacent in the furnace height direction is equal to or larger than a threshold value, the controller 9 It is determined that the upper surface of the char deposition layer is located at a position between the two temperature sensors (the second temperature sensor T2 and the third temperature sensor T3).

  Thus, the position of the upper surface of the char deposition layer in the furnace height direction of the gasification furnace 2 can be estimated with a simple configuration using the temperature sensors T1, T2,. Therefore, it is possible to easily grasp the current height of the char deposition layer and use it for control for bringing the height of the upper surface of the char deposition layer closer to an appropriate state.

  The preferred embodiment of the present invention has been described above, but the above configuration can be modified as follows, for example.

  In the above embodiment, the detection unit has the six temperature sensors arranged side by side in the furnace height direction of the gasification furnace 2, but the number of the temperature sensors may be more or less than the above. Further, the height of the upper surface of the char deposition layer may be detected by another sensor such as an ultrasonic sensor instead of the temperature sensor.

  In the above embodiment, one correction value is selected from seven different correction values according to the degree of deviation of the current height of the char deposition layer in the gasification furnace 2 from the target deposition height. Therefore, the corrected operating frequency is used to calculate the corrected operating frequency. However, the number of correction values is not limited to this, and may be larger or smaller.

  The magnitude (absolute value) of each correction value shown in the above-described embodiment can be understood to represent the increase width or the decrease width when correcting the operating frequency. The present invention is not limited to those shown in the embodiments, and can be freely determined. That is, depending on the degree of deviation of the current height of the char deposition layer from the target deposition height in the gasification furnace 2, the raising width or the lowering width is increased or decreased stepwise at a constant width or an irregular width. Alternatively, the increase or decrease may increase or decrease exponentially.

  Further, when the deviation of the current char deposition layer height from the target deposition height is large, the raising or lowering width for correcting the operating frequency may be smaller than when the deviation is small. For example, it is conceivable to control as follows. In other words, even when the current height of the char deposition layer is significantly lower than the target height, the height of the char deposition layer is slowly increased while the speed of the discharging operation is gradually reduced. Then, when the current height of the char deposition layer rises and approaches the target height, the speed of the discharging operation is slightly reduced, and the rising speed of the height of the char deposition layer is increased. When the current height of the char deposition layer slightly exceeds the target height, the discharging operation is rapidly increased to positively discharge the char, thereby rapidly lowering the height of the char deposition layer.

  In the above embodiment, the char accumulated in the gasification furnace 2 is discharged to the outside of the gasification furnace 2 by the char discharger 4 having the rotary valve 41 and the screw conveyor 42, and the rotary valve 41 and the screw conveyor 42 By changing the rotation speed (in other words, the speed of the discharging operation), the discharging speed of the discharging device is changed. However, the method of changing the discharge speed of the discharge device is not limited to this. For example, the discharging device may be configured such that the pushing member driven by an actuator such as a hydraulic cylinder intermittently repeats a pushing operation (discharging operation) to discharge the char. In that case, the control device 9 can change the discharge speed by controlling the frequency of the pushing operation of the pushing member per unit time to be changed. Alternatively, the opening area of a discharge hole (discharge hole) provided at the bottom of the gasification furnace 2 is configured to be changeable, and the control device 9 performs control to increase or decrease the opening area, so that the discharge speed of the discharge device is increased. May be changed.

  The type and state (particle size, dry state, etc.) of the raw material to be charged into the gasification furnace 2 may be input to the control device 9 in advance, and different correction values may be applied according to the input contents.

  In the above embodiment, the raw material is supplied to the gasification furnace 2 by a fixed amount by the fuel supply device 3, but the present invention is not limited to this, and the raw material input amount may be variable.

  In the above-described embodiment, the gas generated in the gasifier 2 is supplied to the cogeneration system 10. However, the present invention is not limited to this. For example, instead of this, an energy conversion device such as a gas turbine may be used. It may be supplied.

  In the above embodiment, the raw material is dried in the gasification furnace 2. However, the present invention is not limited to this. For example, the raw material may be dried before being supplied to the fuel supply device 3. It may be done.

  In the above-described embodiment, the control for correcting the operating frequency of the discharge device to make the height of the upper surface of the char deposition layer in the gasification furnace 2 close to an appropriate state is performed by the control device for controlling the entire gasification device 1. 9 was performed. However, the present invention is not limited to this, and the above control may be performed by a control device dedicated to the gasifier 2.

  The present invention relates to a gasification furnace 2 in which char is deposited below a region where partial combustion is performed, and in the region where the char is deposited, reduction by the char is performed at a lower temperature than during partial combustion. It can be widely applied to the gasifier 1 provided. That is, the type of the gasifier 2 is not particularly limited to the fixed bed type.

DESCRIPTION OF SYMBOLS 1 Gasifier 2 Gasifier 4 Char discharger (discharger)
Reference Signs List 9 control device 12 storage unit 42 screw conveyor T1 to T6 first to sixth temperature sensors (detection unit)

Claims (3)

A gasification furnace in which the raw material is pyrolyzed to generate gas, and the carbides generated in the process are deposited;
A discharge device for discharging the deposited carbide to the outside of the gasification furnace,
A detection unit that detects the height of the upper surface of the carbide deposition layer,
The discharge based on a difference between the current height of the upper surface of the carbide deposition layer obtained from the detection result of the detection unit and a target deposition height that is a predetermined target height of the upper surface of the carbide deposition layer. A control device that repeatedly performs control for changing the discharge speed of the device from the current discharge speed,
With
The detection unit,
A first temperature sensor;
A second temperature sensor disposed below the first temperature sensor in a furnace height direction of the gasification furnace;
Has,
When the difference between the detection value of the first temperature sensor and the detection value of the second temperature sensor is equal to or greater than a threshold value, the upper surface of the deposited layer of the carbide has the first temperature in the furnace height direction of the gasification furnace. A gasifier which determines that it is located between a sensor and the second temperature sensor . The gasifier according to claim 1, wherein
The control device changes the discharge speed by an increase width or a decrease width according to a difference between the current height of the upper surface of the deposited layer of the carbide obtained by the detection result of the detection unit and the target deposition height. A gasifier characterized by the above. The gasifier according to claim 2, wherein
A storage unit that stores a correction value for changing a discharge speed of the discharge device,
The storage unit stores a plurality of different correction values selected according to the degree of deviation between the current height of the upper surface of the carbide deposition layer obtained from the detection result of the detection unit and the target deposition height. A gasifier characterized in that:

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