JP2012001650A - Method and system for operating gasification furnace - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a method for operating a gasification furnace which can greatly reduce consumption of fossil fuel for raising temperature, and can renew a filter without depending on backwashing.SOLUTION: When operating a gasification furnace 1 for gasifying biomass in, for example, DSS (Daily Start and Stop) operation, pilot-burner operation for combusting biomass in a prescribed excess oxygen atmosphere is carried out after the DSS operation is stopped to keep temperature of the gasification furnace 1. The exhaust gas from the gasification furnace 1 at the pilot-burner operation is fed to a filter element 5 for removing dust from the produced gas of the gasification furnace 1, so as to burn the attached dust for removal.

Description

  The present invention relates to a method for operating a gasification furnace for gasifying biomass such as agricultural products, wood, and plants, and a system therefor.

  BACKGROUND ART Conventionally, as disclosed in, for example, Patent Document 1, a gasification furnace in which woody biomass is gasified and a generated gas is supplied to a power generator such as a gas turbine or a gas engine is known. The one described in this document has an integrated structure in which a dust removal device such as a cyclone or a filter is housed in the same casing as the main body of the gasifier, reducing external costs and reducing equipment costs and suppressing heat dissipation. Like to do.

  In addition, the gasification furnace described in the above-mentioned document has an advantage that tar trouble is unlikely to occur because the generated gas is removed at high temperature and supplied to a gas turbine or the like. Furthermore, since the heat radiation of the entire system is suppressed, the restart time after stopping is shortened, which is suitable for so-called DSS (Daily Start and Stop) operation.

  That is, for example, in the case of a small-scale biomass gasification power plant that is installed next to a sawmill and only covers its power, the sawmill is not operated continuously like a large-scale plant day and night. The plant will also stop operating at night when it is not, but this will cause the temperature of the gasifier to drop to room temperature during the nighttime stop, so it will be necessary to raise the temperature when restarting the next morning. Become.

  As an example at the time of this temperature raising operation, fossil fuel such as kerosene is supplied to the gas turbine to start the operation, and the temperature of the gasifier is adjusted by supplying high-temperature air compressed by a compressor linked to the turbine. Raise. After that, the temperature rises quickly by putting the biomass into the gasifier and burning it, and if it reaches a temperature suitable for biomass gasification, the temperature raising operation is terminated, and normal operation is started. Can do.

Japanese Patent Laid-Open No. 2006-808

  However, as described above, it is uneconomical to use fossil fuels such as kerosene every morning to raise the temperature of the gasifier, and the environment is also adversely affected. In addition, in a small-scale plant that performs DSS operation as described above, there is a problem that it is difficult to perform backwashing as in a large-scale plant for regeneration of the filter.

  That is, in large-scale plants, during operation of the gasification furnace, backwash gas is periodically sprayed from the downstream side of the filter to remove dust, but the backwash gas is such as nitrogen. This is because it is necessary to use such an inert gas, and the equipment cost is high, and the gas generated by gasification contains a tar component, and dust may not be removed depending on the backwash gas.

  In view of these points, an object of the present invention is to provide a gasifier operating method that can greatly reduce the consumption of fossil fuel for raising the temperature of the gasifier and can regenerate the filter without backwashing. There is to do.

  In order to achieve such an object, the present invention pays attention to repetition of operation and stop, such as DSS, and supplies and burns a small amount of biomass so as to maintain the temperature of the gasifier during the stop. At the same time, the exhaust gas in the meantime is supplied to the filter to burn the dust containing a large amount of unburned carbon.

  That is, the present invention is an operation method of a gasification furnace for gasifying biomass, and when the filter for removing dust from the generated gas is provided downstream of the gasification furnace, the gasification furnace After the normal operation is completed, the biomass is burned in a predetermined atmosphere having an air ratio of 1 or more to maintain the temperature of the gasifier, and at the same time, the exhaust gas is supplied to the filter to remove the adhering dust. It is removed by burning.

  If the biomass is burned as described above to maintain the temperature of the gasifier (hereinafter also referred to as seed fire operation), the temperature raising operation at the next restart becomes unnecessary or minimal. As a result, the use of fossil fuels can be greatly reduced. The amount of biomass to be burned in the pilot fire operation is small, and the price as a fuel is very cheap, so it is much more economical than using fossil fuels and also reduces CO2 emissions. it can.

  Moreover, since the biomass is burned in a predetermined atmosphere with an air ratio of 1 or more in the seed fire operation, oxygen is contained in the exhaust gas, and this is attached by supplying it to the filter of the gasifier. The dust can be burned and removed, and its dust removal function can be restored.

  In other words, in the case of DSS operation suitable for a small plant as an example, low-cost biomass can be burned while the gasifier is shut down at night, and the temperature can be maintained until the next morning restart. In the meantime, the filter can be regenerated at the same time.

  Here, when the dust adhering to the filter is burned and removed as described above, the filter may be damaged if the temperature becomes excessively high due to the combustion. Therefore, combustion of the dust adhering to the filter becomes gentle and it is easy to avoid a rapid temperature rise. Preferably, at least a sensor for detecting the temperature state of the filter is provided, and in the case of the pilot fire operation, based on the filter temperature detected by the filter temperature sensor, the biomass and combustion for the gasifier are used. The supply amount of at least one of the air is controlled.

  More preferably, a gasification furnace temperature sensor for detecting the temperature state of the gasification furnace is also provided, and the supply amount of biomass and combustion air is based on not only the filter temperature but also the temperature state of the gasification furnace. Is to control.

  What is important is that the filter temperature does not exceed the melting temperature of the ash contained in the dust or the heat resistance temperature of the filter itself, and the same applies to the temperature of the gasifier. Therefore, for example, until at least one of the gasification furnace temperature and the filter temperature reaches an upper limit value such as the melting temperature of the ash, biomass and combustion air are supplied to the gasification furnace, and either temperature is the upper limit value. The supply may be stopped as soon as the value is reached.

  After that, if the gasifier temperature decreases to a predetermined lower limit value, the supply of biomass and combustion air is started again, the biomass is combusted in the gasifier, and the dust is combusted in the filter. Good. Thus, the filter can be prevented from being damaged by simple control that repeats combustion and its stop.

  In addition, when the supply of biomass or combustion air to the gasifier is started, the supply amount of combustion air may be gradually increased during an initial predetermined period. In this way, even if there is a large response delay in the control of the biomass supply amount, the combustion air can be gradually increased in response to this, and combustion air with a high oxygen concentration flows through the filter and combustion occurs. It can avoid becoming intense. Moreover, even if biomass remains in the gasification furnace at the start of supply of combustion air, it is possible to avoid a situation in which it starts to burn and the temperature rapidly rises.

  Further, the supply amount of combustion air to the gasifier may be substantially constant, and the biomass supply amount may be controlled based on the detected gasifier temperature. That is, while the supply amount of combustion air is sufficiently increased to create an oxygen-excess atmosphere, the supply amount of biomass is increased if the gasifier temperature decreases, and conversely, the supply amount of biomass is increased if the gasifier temperature increases. By reducing the temperature, the temperature state of the gasification furnace and the filter can be maintained.

  Furthermore, a bypass passage is provided for guiding the exhaust gas discharged from the gasification furnace to the chimney without passing through the filter. When the biomass is burned, the exhaust gas is determined based on the filter temperature detected by the filter temperature sensor. The exhaust gas flow rate to the filter may be adjusted by allowing a part of the gas to flow through the bypass passage.

  And if the dust adhering to the filter is burned while maintaining the temperature state of the gasifier, this dust will burn out and the filter temperature will not rise after that, so this filter temperature will fall below the predetermined value If so, it may be determined that the regeneration of the filter has been completed, the amount of biomass supplied may be reduced, and the gasifier temperature maintained at the lower limit.

  In other words, the present invention is intended for a gasifier operating system for gasifying biomass, and a filter for removing dust from the product gas is provided downstream of the gasifier. And at least a filter temperature sensor for detecting the temperature state of the filter, and a biomass and combustion for the gasifier based on the filter temperature detected by the filter temperature sensor after the normal operation of the gasifier is completed. And a control means for controlling the supply amount of at least one of the air and burning the biomass in a predetermined atmosphere having an air ratio of 1 or more (that is, performing a seed fire operation).

  The operation system further includes a gasifier temperature sensor for detecting a temperature state of the gasifier, and the control means is configured to adjust the gasifier temperature detected by the gasifier temperature sensor and the filter temperature. Based on this, the supply amount of at least one of biomass and combustion air to the gasifier may be controlled.

  The exhaust gas discharged from the gasification furnace during execution of the seed fire operation may be provided with a bypass passage for guiding the exhaust gas from the filter to the chimney. The dust combustion gas can be discharged from the chimney by bypassing the power generation equipment.

  Further, it may be provided with a bypass passage for guiding the exhaust gas discharged from the gasification furnace when the biomass is burned to the chimney without passing through the filter, so that the gas supply from the gasification furnace is supplied to the filter. It is possible to control the temperature of the filter by adjusting the flow rate of the exhaust gas during the seed fire operation.

  From the above, according to the operation method of the gasification furnace according to the present invention, paying attention to the repetition of operation and stop, such as DSS, for example, a seed light for maintaining the temperature after the normal operation of the gasification furnace is finished. During the operation, the exhaust gas from the gasifier was supplied to the filter to burn the dust, greatly reducing the consumption of fossil fuel for the temperature rise of the gasifier at the subsequent restart. In addition to being able to reduce, it is possible to regenerate the filter without relying on backwashing by effectively using the exhaust gas during the seed fire operation.

It is a distribution diagram showing an example of a gasifier operation system concerning an embodiment of the invention. An example of the structure of the gasification furnace is shown. FIG. (A) is a longitudinal sectional view along the center line of the casing, and a transverse sectional view taken along line (b)-(b) is FIG. (B). It is a block diagram which shows an example of the control system for the seed gas operation | movement of the same gasifier. It is a flowchart which shows an example of the control procedure of seed-fire operation. It is a time chart which shows notionally an example of the correlation with the change of the supply amount of the biomass and combustion air in a seed-fire operation, and the temperature change of a gasifier and a filter. It is the FIG. 1 equivalent view which concerns on other embodiment which provided the bypass pipe which bypasses a filter chamber.

  Hereinafter, preferred embodiments of the present invention will be described with reference to the drawings. FIG. 1 is a system diagram of a gasification furnace operation system according to an embodiment, and this system is used in a gasification power plant as an example. In this plant, biomass is gasified in the gasification furnace 1 and reformed into a gas with higher energy conversion efficiency before being used for operation of power generation equipment.

-Overall configuration of the plant-
In the example of the figure, the biomass that is fuel is woody biomass such as sawmill sawdust, thinned wood, construction waste, etc., and these are supplied to the gasification furnace 1 in the form of chips by a supply mechanism 2 including, for example, a hopper and a conveyor. Supplied. The illustrated gasification furnace 1 is a fluidized bed type as an example. As shown in FIG. 2, a fluidized sand layer 1a is formed in the furnace and fluidized by air fed from below. Yes.

  The air sent from below is pressurized and heated by a compressor 9 described later, and is heated while being dispersed by the fluidized sand fluidized by the air, and a part of it is burned. In combination with this, it is thermally decomposed in a short time.

  Further, the gas generated by the pyrolysis of biomass is discharged from the upper part of the gasification furnace 1, and relatively large dust is centrifuged in the cyclone 3, and then guided to the filter chamber 4. As will be described in detail later, when the product gas guided to the filter chamber 4 passes through the filter element 5, small dust that cannot be separated by the cyclone 3 is collected. The gas that has passed through the filter element 5 is guided to the gas turbine combustor 7 by the product gas pipe 6.

  Then, the generated gas is combusted in the gas turbine combustor 7, and high-temperature and high-pressure exhaust gas is supplied to the turbine 8. In the illustrated example, a compressor 9 and a generator 10 are connected to the turbine 8, and the generator 10 is operated by the rotation of the turbine 8, and the compressor 9 compresses air and gas is supplied through the pressurized air supply pipe 11. The gas is supplied to the converter 1 and the gas turbine combustor 7.

  That is, the pressurized air supply pipe 11 includes an upstream side common pipe 11a connected to the compressor 9, and a first and second branch pipes 11b and 11c divided into two branches on the downstream side thereof. The downstream end of the one branch pipe 11b is connected to the air intake port of the gas turbine combustor 7 so as to supply air for burning the product gas as described above.

  On the other hand, the downstream end of the second branch pipe 11c is connected to the air intake 1b (see FIG. 2) at the lower part of the gasification furnace 1, and the air supplied thereby is the fluidized bed in the furnace as described above. Is sent from below to fluidize the fluidized sand. The air flowing through the first and second branch pipes 11b and 11c is heated by exchanging heat with the exhaust gas from the turbine 8 in the common heat exchanger 13. In addition, the exhaust gas that has passed through the heat exchanger 13 is used for generating steam in the boiler 14, so that exhaust heat is utilized. The exhaust gas that has passed through the boiler 14 is exhausted from the chimney 15.

  Gasification of biomass is promoted by supplying the pressurized and heated air to the gasification furnace 1 as described above. Biomass is usually gasified at a relatively low temperature of about 650 ° C., but in order to maintain the temperature state, it is necessary to burn a part of the biomass in the gasification furnace 1. If the air sent to the gasification furnace 1 is pressurized and heated as described above, a larger amount of heat can be brought into the furnace, and the amount of biomass to be burned can be reduced.

  Further, by supplying such pressurized air, the inside of the gasification furnace 1 can be brought to approximately the same pressure state as in the gas turbine combustor 7. Therefore, the gas generated in the gasification furnace 1 can be introduced into the gas turbine combustor 7 without cooling, and can be burned without removing the tar component contained in the gas. As a result, the fuel utilization efficiency is improved and handling troubles due to the adhesion of tar components and the like are avoided.

  A reference numeral 16 in FIG. 1 indicates a temperature sensor for detecting the temperature state of the gasification furnace 1 (hereinafter referred to as the gasification furnace temperature sensor 16). Used to maintain within proper range. Further, as will be described in detail later, in the example of the figure, temperature sensors 22 and 23 (filter temperature sensors for detecting the temperature states of the upper and lower portions of the filter chamber 4 respectively. Also referred to as sensor 23).

  Further, in this embodiment, a valve 17 is interposed in the generated gas pipe 6 and a bypass pipe 18 (bypass passage) branched from the upstream side to the chimney 15 is connected. 18 is also provided with a valve 19. During normal operation, the valve 19 is closed, and the product gas from the gasifier 1 is sent to the gas turbine combustor 7 through the valve 17.

-Structure of gasifier-
In the gasification power plant of this embodiment, as shown in FIG. 2, the filter element 5 is accommodated in the casing 20 of the gasification furnace 1, in other words, the filter chamber 4 is placed in the casing 20 of the gasification furnace 1. Is formed. Further, the casing 20 has a double shell structure so as to suppress the heat radiation of the gasification furnace 1 and the filter element 5 as much as possible.

  The specific structures of the gasification furnace 1, the filter chamber 4 and the casing 20 shown in the figure are the same as those described in Patent Document 1 as an example, and a detailed description thereof will be omitted, but the casing 20 has an upper end and a lower end. Each is closed and has a substantially cylindrical shape, and has a space 20c between the inner shell 20a and the outer shell 20b as shown in the figure. For example, the space portion 20c may be an air layer, may be filled with a heat shielding material, or may be heat-insulated by making a vacuum. By housing in the casing 20 having such a double shell structure, it is advantageous to suppress the heat radiation of the gasification furnace 1 and the filter element 5 and maintain the temperature state.

  In the example shown in the figure, the gasification furnace 1 is disposed substantially along the center line in the vertically extending casing 20, and a plurality of filter elements 5 are arranged at intervals in the circumferential direction so as to surround the upper half of the gasification furnace 1. It is out. Further, the inside of the casing 20 is vertically divided by a partition plate 21 above the upper end of the gasification furnace 1, and below that, a filter upstream chamber 4 a that is an upstream side of the flow of the product gas is provided above. Similarly, filter downstream chambers 4b are respectively formed.

  As shown in FIG. 2 (b), a plurality of round holes are formed on the partition plate 21 along the circumference, and the upper portion of the filter element 5 is inserted into each of the round holes. Has been. The filter element 5 is made of, for example, a ceramic filter, and has a cylindrical peripheral wall portion that extends in the vertical direction and a hemispherical bottom wall portion that closes its lower end, and these wall portions extend from the outside to the inside of the filter element 5. Dust in the passing gas is collected.

  In the example shown in the figure, an introduction pipe 3 a for guiding the generated gas from the cyclone 3 to the filter chamber 4 is arranged on substantially the same circumference as the filter element 5, and from here, below the partition plate 21 in the filter chamber 4, that is, upstream of the filter. After being guided to the chamber 4a, the product gas diffuses throughout the filter upstream chamber 4a. The product gas diffused in this way passes through the wall of the filter element 5 to reach the inside thereof, and after naturally rising, flows into the filter downstream chamber 4b above the partition plate 21 from the upper end opening of the filter element 5. And it flows out to the production | generation gas pipe | tube 6 which penetrated the casing 20 so that this filter downstream chamber 4b might be faced.

  In this embodiment, in order to detect the temperature state of the product gas passing through the filter element 5 as described above and monitor the temperature so that the temperature does not become too high, it is associated with the upper part of the peripheral wall portion of the filter element 5. An upper temperature sensor 22 is provided. As an example, the upper temperature sensor 22 is provided in the filter element 5 positioned in the vicinity of the introduction pipe 3a into which the generated gas from the cyclone 3 is introduced, as shown in FIG.

  In this embodiment, not only the upper temperature sensor 22 but also a lower temperature sensor 23 is disposed in association with the lower portion of the peripheral wall portion of the filter element 5. In the example shown in the figure, the lower temperature sensor 23 is another filter element located at a substantially diagonal position on the circumference surrounding the gasification furnace 1 with respect to the filter element 5 provided with the upper temperature sensor 22 as described above. 5 is provided.

  These temperature sensors 22 and 23 are not in direct contact with the filter element 5, but are spaced apart from the outer peripheral surface of the peripheral wall portion of the filter element 5, that is, the upstream side surface of the flow of the generated gas. Are arranged. As an example, this interval corresponds to the assumed maximum thickness of dust adhering to the peripheral wall portion of the filter element 5. In other words, the temperature sensors 22, 23 are connected to dust at the start of filter regeneration. It arrange | positions so that the boundary layer of may be contacted.

  Thus, since it arrange | positions at the space | interval which contacts the dust boundary layer, while being able to detect the temperature state of the filter element 5 correctly with the temperature sensors 22 and 23, for example like earthquake motion Even when external vibration is applied, there is no concern that the temperature sensors 22 and 23 are in direct contact with the filter element 5 to cause damage.

  Further, in this embodiment, as shown in FIG. 1, for example, an electric air pump 24 capable of supplying air to the gasification furnace 1 is provided. This is for supplying biomass combustion air to the gasification furnace 1 for the seed fire operation described below. After the normal operation of the gasifier 1 is completed, the seed fire operation is performed in order to maintain the temperature of the gasifier 1 at an appropriate temperature until the next morning.

  As shown in the drawing, the downstream end of the outside air supply pipe 25 connected to the discharge port of the air pump 24 is connected to the second branch pipe 11c of the pressurized air supply pipe 11, and the air pump is connected via the second branch pipe 11c. The air from 24 is supplied to the gasification furnace 1. The outside air supply pipe 25 is provided with a valve 26 capable of adjusting the air flow rate and a flow rate sensor 27 for detecting the flow rate. The supply amount of combustion air is adjusted based on the temperature state.

  In the example shown in the figure, a branch pipe 28 that branches from the middle of the outside air supply pipe 25 and reaches below the filter chamber 4 is provided, and a valve 29 that can adjust the air flow rate is also provided in the branch pipe 28. ing. For example, when the operation of the plant is stopped for several days on a weekend or the like, the seed fire operation is not performed. At this time, the valve 29 is opened after the normal operation of the gasification furnace 1 is finished, and the filter element is still hot. 5 is supplied with outside air to burn the dust.

-Seed operation of gasifier-
Below, the seed fire operation in the gasification power plant of this embodiment is demonstrated in detail with reference to FIGS. FIG. 3 is a block diagram illustrating an example of a control system for the seed fire operation, and FIG. 4 is a flowchart illustrating an example of a control procedure for the seed fire operation. FIG. 5 conceptually shows an example of the correlation between changes in the supply amounts of biomass and combustion air during the seed fire operation and changes in the temperatures of the gasification furnace and the filter.

  As an example, the gasification power plant of this embodiment is provided next to a sawmill and is a small-scale plant that covers only the power, and the plant also stops operation at night when the sawmill is not operating. Therefore, after the normal operation of the gasifier 1 is finished in the evening according to the DSS operation cycle, the gasifier 1 is maintained at a suitable temperature until the next morning by performing a seeding operation, and the gasifier in the meantime. The exhaust gas from 1 is supplied to the filter element 5 and the dust adhering thereto is burned and removed.

  Such a pilot operation is performed by the process controller 30 of the gasification power plant in this embodiment. At this time, the process controller 30, as schematically shown in FIG. 3, signals from the gasifier temperature sensor 16, signals from the temperature sensors 22 and 23 above and below the filter, and the flow rate of the outside air supply pipe 25. At least a signal from the sensor 27 is input, the supply amount of the biomass to the gasification furnace 1 is adjusted by the control of the supply mechanism 2, and the supply amount of the combustion air is controlled by the opening degree control of the valve 26 of the outside air supply pipe 25. Adjust.

  That is, in the example shown in the figure, the process controller 30 operates the operation amount (for example, screw conveyor) of the supply mechanism 2 in accordance with the signal from the gasifier temperature sensor 16 and the signals from the upper and lower filter temperature sensors 22 and 23. ) And the opening degree of the valve 26 in accordance with signals from the temperature sensors 16, 22, and 23, and the biomass supply amount control unit 30 a that adjusts the biomass supply amount to the gasifier 1. And a combustion air supply amount control unit 30b that controls and adjusts the flow rate of air in the outside air supply pipe 25, that is, the supply amount of combustion air to the gasification furnace 1.

  In the example shown in the figure, the combustion air supply control unit 30b feeds back a signal from the flow sensor 27 to correct the opening of the valve 26. The combustion air supply amount control unit 30b and the biomass supply amount control unit 30a are realized by the process controller 30 executing a control program for the seed fire operation, in other words, in this embodiment. The process controller 30 includes the control units 30a and 30b in the form of software.

  Next, a specific control procedure of the seed fire operation will be described with reference to the time chart of FIG. 5 based on the flowchart of FIG. When it is selected in advance that the pilot operation is performed by the operator's operation input, for example, the daily operation of the gasification power plant is terminated according to the operation cycle of the DSS, and the normal operation of the gasification furnace 1 is terminated. Then, it is determined whether or not a predetermined start condition for the seed fire operation is satisfied (step S1: start condition satisfied?).

  As an example, in this embodiment, a stop preparation operation is performed in which the inside of the casing 20 containing the gasification furnace 1 and the filter element 5 is reduced to normal pressure (atmospheric pressure) after the normal operation ends. This is because the combustion pump air cannot be supplied to the high-pressure gasification furnace 1 by the air pump 24 having a small output even if the seed fire operation is performed in the pressurized field during the normal operation. In other words, by performing the seed fire operation in the normal pressure field, it is not necessary to provide a high-pressure compressor only for the seed fire operation, and an increase in equipment cost can be avoided.

  Note that during the stop preparation operation, the operation of the turbine 8 may be continued for a while to supply pressurized air so that the biomass remaining in the gasification furnace 1 can be burned. As described below, when the start-up operation is started, if high-temperature biomass remains in the gasification furnace 1, combustion starts at once as soon as the supply of combustion air is started. This is because the temperature may increase.

  Then, if the stop preparation operation is continued for a predetermined time and the inside of the casing 20 becomes normal pressure, or if it is detected by a pressure sensor (not shown) that the inside of the casing 20 becomes normal pressure, in the step S1 It is determined that the start condition for the start-up operation is satisfied (YES), the valve 26 of the outside air supply pipe 25 is opened along with the operation of the air pump 24, and the supply of combustion air to the gasifier 1 is started. Then, the supply of biomass to the gasification furnace 1 is started (step S2).

  Further, at the same time as the supply of biomass and combustion air to the gasifier 1 is started, the valve 17 of the product gas pipe 6 to the gas turbine combustor 7 is closed and the valve 19 of the bypass pipe 18 is opened. To do. If it carries out like this, the exhaust gas discharged | emitted from the gasification furnace 1 in the seed fire operation mentioned below will pass through the filter element 5, will bypass the gas turbine combustor 7, etc., and will be exhausted from the chimney 15.

  Here, the amount of biomass supplied for the seed fire operation is very small as compared with the normal operation of the gasifier 1, and may be about 1/5 to 1/10. As an example, when the supply mechanism 2 includes a screw conveyor, the maximum rotation speed is set to 100%, and the ratio (rotation rate) of the rotation speed during normal operation is about 50 to 60%. Is about 5 to 10%. And the rotation rate of the screw conveyor at the time of starting supply of biomass is said 5-10% for a while considering the response delay until biomass is actually supplied to the gasification furnace 1, that is, It is maintained at the maximum amount of movement during the seed fire operation.

  That is, as shown in FIG. 5 as times t0 to t1, the outside air supply pipe is kept constant while maintaining the rotation rate of the screw conveyor, that is, the amount of biomass supplied to the gasification furnace 1, for the initial predetermined period when the seed fire operation is started. The opening of the valve 25 is gradually increased to gradually increase the supply amount of combustion air (step S3 in the flow of FIG. 4). In this way, even if the response delay of the biomass supply described above is large, the amount of combustion air is gradually increased so as to correspond to this.

  Further, even if biomass remains in the gasification furnace 1 when starting the supply of combustion air, since the combustion air supplied at the beginning is small, the remaining biomass starts to burn at once and the temperature is increased. A sudden rise is avoided.

  Then, the combustion air is increased as described above until reaching a preset amount (set air supply amount) (NO in step S4), while if the set air supply amount is reached (YES), then the combustion air is increased. Is fed back to control the degree of opening of the valve 26 (step S5). The set air supply amount is set to a predetermined atmosphere having an air ratio of about 1.3 to 3.5 with respect to the biomass supply amount by the maximum operation amount of the supply mechanism 2 in the above-described seed fire operation. Is set.

  Thus, the biomass supply amount is increased or decreased according to the filter temperature Tf while the supply amount to the gasifier 1 is controlled to a substantially constant set supply amount. That is, if the filter temperature Tf rises, the supply amount of biomass is gradually increased, the supply of oxygen to the filter is reduced, the combustion is moderated, and the filter temperature Tf is lowered. Conversely, if the filter temperature Tf decreases, the supply amount of biomass is gradually decreased, and the supply of oxygen to the filter is increased, thereby increasing the filter temperature Tf.

  As a result, as shown at times t1 to t2 in FIG. 5, as the filter temperature Tf increases, the operation rate of the supply mechanism 2 (in the example of the figure, the rotation rate of the screw conveyor) decreases, and the gasification furnace 1 is supplied to the gasifier 1. The biomass supply will gradually decrease. As the filter temperature Tf, the higher one of the temperatures detected by the upper and lower filter temperature sensors 22 and 23 may be employed.

  The process controller 30 monitors the gasifier temperature Tbed and the filter temperature Tf while controlling the supply amounts of biomass and combustion air to the gasifier 1 as described above. As an example, if the filter temperature Tf does not increase and falls below a predetermined lower limit value (about 530 ° C. in the figure), it is determined that the regeneration of the filter has ended (YES in step S6), and the procedure after step S10 described later is performed. On the other hand, if the filter temperature Tf is equal to or higher than the lower limit value (NO in step S6), it is determined whether either the filter temperature Tf or the gasifier temperature Tbed is equal to or higher than a predetermined upper limit value (step S7). .

  The upper limit value may be the melting temperature of the ash in the dust adhering to the filter element 5 or the heat resistance temperature of the filter element 5 (about 600 ° C. in the example in the figure), and the gasifier temperature Tbed and the filter temperature. If all of Tf are less than the upper limit value (NO in step S7), the process returns to step S5 to continue the supply of biomass and combustion air to the gasification furnace 1, while either temperature is equal to or higher than the upper limit value. If it becomes (it is YES at Step S7), supply of biomass and combustion air will be stopped temporarily (Step S8).

  At time t2 in FIG. 5, the gasifier temperature Tbed has reached the upper limit value. In response to this, the valve 26 of the outside air supply pipe 25 is fully closed and the operation of the supply mechanism 2 is also stopped. The supply of biomass and combustion air to 1 is stopped. As a result, both the gasifier temperature Tbed and the filter temperature Tf are uniformly decreased at times t2 to t3, and the system waits until they are less than the lower limit value (NO in step S9).

  If at least one of the gasifier temperature Tbed or the filter temperature Tf falls to the lower limit value (YES in step S9), the process returns to step S2 to supply biomass and combustion air to the gasifier 1. Resume. Thereby, the combustion of biomass starts again in the gasifier 1, and the gasifier temperature Tbed and the filter temperature Tf rise as shown after time t3 in FIG. At time t4 in the figure, the filter temperature Tf reaches the upper limit value, and accordingly, the supply of biomass and combustion air to the gasification furnace 1 is stopped in the same manner as described above, and the gasification furnace temperature is from time t4 to t5. Both Tbed and filter temperature Tf will decrease.

  In this way, the simple control of repeatedly supplying and stopping the biomass and combustion air to the gasification furnace 1 prevents the temperature of the gasification furnace 1 and the filter element 5 from rising excessively. Can be prevented from being damaged.

  And if the dust adhering to the filter element 5 is burned while maintaining the temperature of the gasification furnace 1 at the lower limit value or more, this dust will burn out and the filter temperature Tf will not rise. That is, as shown in time t5 to t6 in FIG. 5, the filter temperature Tf does not increase despite the biomass and combustion air being supplied to the gasifier 1, and if it decreases to the lower limit value ( At time t6), YES is determined in step S6 of the flow of FIG. 4, that is, it is determined that the filter regeneration has ended.

  In response to this filter regeneration end determination, the process controller 30 minimizes the amount of biomass supplied so that only the pilot operation that maintains the gasifier temperature Tbed is continued (step S10). For example, according to the detected value of the gasifier temperature Tbed, the supply mechanism 2 is operated so that this is maintained at the lower limit value. If the gasifier temperature Tbed is lowered, the amount of biomass supplied is slightly increased, and if the temperature is increased, it is decreased slightly, so that it can be maintained at about 530 ° C.

  Thus, after the completion of the filter regeneration, the seed-fire operation is continued, and the minimum amount of biomass is burned to maintain the temperature of the gasifier 1 at an appropriate temperature. If the operation resumption time is reached, or if the operation of the plant is resumed by the operator's operation input, and so on, the end condition of the seed igniting operation is established (step S11), the process controller 30 sends the process to the gasifier 1 The supply of biomass and combustion air is stopped (step S12), and the control of the seed fire operation is ended (end).

  As described above, according to the operation method of the gasification furnace 1 according to the embodiment described above, in a small-scale gasification power plant that performs DSS operation using waste material from a sawmill as biomass (fuel), for example, normal operation in the daytime is performed. At the end of the night, the gasifier 1 can be operated to ignite the low-cost biomass little by little, and can be maintained at a suitable temperature until the next morning restart. By supplying the exhaust gas having a low oxygen concentration discharged from 1, the dust adhering to the filter element 5 can be burned and removed.

  Therefore, the fossil fuel such as kerosene used for raising the temperature of the gasifier 1 at the next morning restart can be greatly reduced, or the consumption of the fossil fuel can be eliminated. And environmental compatibility is high. In addition, there is no need for backwashing with an inert gas for filter regeneration, and it is only necessary to provide an air pump 24 or the like for supplying outside air to the gasification furnace 1 for the above-mentioned seed igniting operation. Can be applied to a relatively small plant.

  In this embodiment, the temperature state of the gasifier 1 is detected by the gasifier temperature sensor 16, and the temperature state of the filter element 5 is detected by the upper and lower temperature sensors 22, 23. Since the supply amount of biomass and combustion air to the gasification furnace 1 is controlled, it is possible to prevent the gasification furnace 1 and the filter element 5 from being damaged due to excessive temperature rise.

-Other embodiments-
In addition, description of embodiment mentioned above is only an illustration essentially, and does not intend restrict | limiting this invention, its application thing, or its use. For example, in the above-described embodiment, the supply amount of biomass and combustion air to the gasifier 1 is controlled based on the gasifier temperature Tbed and the filter temperature Tf during the seed fire operation. It is also possible to control based on only the filter temperature Tf.

Further, exhaust gas from the gasification furnace 1 is supplied during the start-up operation to burn the dust of the filter element 5. At this time, the valve 29 of the branch pipe 28 of the outside air supply pipe 25 is opened. Further, outside air may be supplied to the filter element 5. Further, as shown in FIG. 6 as an example, the bypass pipe 31 is branched from the introduction pipe 3 a from the cyclone 3 to the filter chamber 4 and reaches the chimney 15. (Bypass passage) may be connected so that exhaust gas discharged from the gasification furnace 1 can be guided to the chimney 15 without passing through the filter chamber 4. The bypass pipe is also provided with a valve 32, and the valve 32 is closed during normal operation.

  During the pilot fire operation, the valve 32 is opened, and a part of the exhaust gas from the gasification furnace 1 is circulated through the bypass pipe 31, and the opening of the valve 32 is increased or decreased based on the filter temperature Tf. The exhaust gas flow rate to the chamber 4 may be adjusted. Thus, the filter temperature Tf can also be controlled by adjusting the flow rate of the exhaust gas.

  Moreover, in the said embodiment, although the gasification furnace 1 is accommodated in the casing 20 of the double shell structure with the filter element 5, it is not restricted to this, The casing 20 may not be a double shell structure. However, the filter element 5 may not be accommodated in the casing common to the gasification furnace 1.

  Moreover, although the woody biomass is illustrated as the fuel supplied to the gasifier 1 in the embodiment, this is a biomass other than the woody material such as livestock manure, food waste, and sewage sludge. There may be.

  According to the operation method of the gasifier according to the present invention, the filter is regenerated by the seed-fire operation using biomass after the end of the normal operation, and the consumption of fossil fuel for raising the temperature can be significantly reduced at the time of restart. For example, it is suitable for application to a relatively small plant that performs DSS operation.

1 Gasification furnace 2 Supply mechanism (control means)
4 Filter chamber 5 Filter element 15 Chimney 16 Gasifier temperature sensor 18 Bypass pipe (bypass passage)
20 Double-shell casing 22 Upper filter temperature sensor 23 Lower filter temperature sensor 25 Outside air supply pipe (control means)
26 Valve (control means)
30 Process controller (control means)
30a Biomass supply control unit 30b Combustion air supply control unit

Claims (12)

A gasification furnace operating method for gasifying biomass,
A filter for removing dust from the product gas is provided downstream of the gasifier,
After the normal operation of the gasifier, the biomass is burned in a predetermined atmosphere having an air ratio of 1 or more, the exhaust gas is supplied to the filter, and the adhering dust is burned and removed. The operation method of the gasifier. At least a filter temperature sensor for detecting the temperature state of the filter;
The gasification according to claim 1, wherein when the biomass is burned, the supply amount of at least one of biomass and combustion air to the gasification furnace is controlled based on a filter temperature detected by the filter temperature sensor. Furnace operation method. A gasifier temperature sensor for detecting a temperature state of the gasifier is further provided;
The supply amount of at least one of biomass and combustion air to the gasifier is controlled based on the gasifier temperature detected by the gasifier temperature sensor and the filter temperature. Gasifier operation method.   The biomass and combustion air are supplied to the gasifier until at least one of the gasifier temperature and the filter temperature reaches a predetermined upper limit value, and the supply is stopped when the upper limit value is reached. The gasification furnace operating method according to claim 3, wherein the supply is resumed when the temperature falls to a predetermined lower limit value.   5. The gasifier operation according to claim 3, wherein the supply amount of the combustion air is gradually increased during an initial predetermined period in which supply of biomass and combustion air to the gasifier is started. Method.   The gasifier operation according to any one of claims 3 to 5, wherein the supply amount of biomass is controlled based on the gasifier temperature while the supply amount of combustion air to the gasifier is substantially constant. Method. A bypass passage is provided for guiding the exhaust gas discharged from the gasification furnace to the chimney without passing through the filter,
When the biomass is burned, an exhaust gas flow rate to the filter is adjusted by causing a part of the exhaust gas to flow through the bypass passage based on a filter temperature detected by the filter temperature sensor. The gasifier operation method according to any one of the above.   During the supply of biomass and combustion air to the gasifier, the filter temperature does not increase, and if it falls below a predetermined value, it is determined that the regeneration of the filter has ended, and the gasifier temperature becomes the lower limit value. The gasifier operation method according to any one of claims 2 to 7, wherein a biomass supply amount is controlled. A gasification furnace operating system for gasifying biomass,
A filter for removing dust from the product gas is provided downstream of the gasifier,
A filter temperature sensor for detecting at least the temperature state of the filter;
After the normal operation of the gasifier is finished, the supply amount of at least one of biomass and combustion air to the gasifier is controlled based on the filter temperature detected by the filter temperature sensor, and the biomass is Control means for burning in a predetermined atmosphere having an air ratio of 1 or more. A gasifier temperature sensor for detecting a temperature state of the gasifier;
The control means controls a supply amount of at least one of biomass and combustion air to the gasifier based on a gasifier temperature detected by the gasifier temperature sensor and the filter temperature. Item 10. The gasifier operating system according to Item 9.   11. The gasifier operating system according to claim 9, further comprising a bypass passage for guiding exhaust gas discharged from the gasifier when the biomass is burned from the filter to a chimney.   The gasification as described in any one of Claims 9-11 provided with the bypass channel for guide | inducing the waste gas discharged | emitted from a gasification furnace when burning the said biomass to a chimney without passing through the said filter. Furnace operation system.

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