JP2013088033A - Biomass pretreatment unit, and biomass and coal mixed-firing system - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a biomass pretreatment unit and a biomass and coal mixed-firing system, capable of more efficiently crushing biomass for easy firing.SOLUTION: The biomass pretreatment unit supplies biomass 140 to a crushing apparatus 26 for crushing the biomass 140 and includes: a biomass supply tank 24 to supply the biomass 140; an indirect heating means (vapor 203a) to preheat the interior of the biomass supply tank 24 by indirect heating; a feeder 25 to supply biomass preheated in the biomass supply tank 24 to the crushing apparatus 26; and a direct heating means to introduce part 150b of a boiler exhaust gas to the inside thereof from the side of the crushing apparatus of the feeder 25 and making the preheated biomass brittle while heating the preheated biomass to a predetermined temperature within the feeder 25.

Description

  The present invention relates to a biomass pretreatment unit and a biomass-coal co-firing system for supplying biomass to a pulverizing apparatus for pulverizing biomass.

In recent years, CO ₂ emission reduction has been promoted from the viewpoint of global warming. In particular, fossil fuels such as coal and heavy oil are often used as fuel in combustion facilities such as power generation boilers, but these fossil fuels cause global warming due to the problem of CO ₂ emissions, and protect the global environment. Its use is being regulated from the viewpoint of In addition, from the viewpoint of depletion of fossil fuels, the development and commercialization of alternative energy resources are required. Therefore, as an alternative to fossil fuels, the use of fuel using biomass has been promoted. Biomass is an organic substance resulting from photosynthesis, and includes biomass such as wood, vegetation, crops, and moss. By converting this biomass into fuel, the biomass can be effectively used as an energy source or an industrial raw material.

  From the viewpoint of highly efficient use of biomass, which is renewable energy, biomass is used as a fuel. One of the methods used as fuel is a method in which biomass solids are pulverized and pulverized and supplied to a pulverized coal-fired boiler for use as fuel. In addition, as described in Patent Document 1 and Patent Document 2, there are some which are used as fuel after carbonizing biomass.

JP 2007-23239 A JP 2008-209080 A

  Here, the biomass is softer and more fibrous than solid fossil fuels such as coal. For this reason, in order to grind | pulverize and pulverize biomass solid substance, more time and output are required rather than grind | pulverize coal and pulverize. That is, biomass has a lower pulverization capacity than coal. On the other hand, like patent document 1 and patent document 2, by carbonizing biomass, it can embrittle and can make it easy to grind | pulverize. However, impurities such as tar may be discharged during biomass carbonization. When impurities are discharged, a process for removing them and maintenance are required.

  The present invention has been made in view of the above, and it is an object of the present invention to provide a biomass pretreatment unit and a biomass-coal mixed combustion system that can pulverize biomass more efficiently and facilitate combustion. To do.

  1st invention of this invention for solving the subject mentioned above is a biomass pre-processing unit which supplies biomass to the grinding | pulverization apparatus which grind | pulverizes biomass, Comprising: The biomass supply tank which supplies the said biomass to a feeder, The said biomass An indirect heating means for indirectly heating the inside of the supply tank to preheat the biomass, a feeder for supplying preheated biomass preheated and heated in the biomass supply tank to the pulverizer, and from the end of the feeder on the pulverizer side, And a direct heating means for introducing the boiler exhaust gas into the feeder and embrittlement while heating the preheated biomass up to a predetermined temperature in the feeder.

  A second invention is the biomass pretreatment unit according to the first invention, wherein the direct heating temperature in the feeder is within a range of non-carbonizing temperature of the biomass.

  A third invention is the biomass pretreatment unit according to the first or second invention, wherein the indirect heating means is low-temperature reheat steam.

  A fourth invention is the biomass pretreatment unit according to any one of the first to third inventions, wherein the direct heating means is exhaust gas from a boiler.

  A fifth invention is the biomass pretreatment unit according to any one of the first to fourth inventions, wherein the biomass heating exhaust gas that contributes to heating in the feeder is supplied to the boiler furnace. .

  A sixth invention includes a biomass pulverization apparatus including any one of the first to fifth biomass pretreatment units, a coal pulverization apparatus for pulverizing a coal raw material, biomass powder pulverized by the biomass pulverization apparatus, and coal A biomass-coal mixed combustion system including a boiler furnace to which coal powder pulverized by a pulverizer is supplied.

  The pretreatment unit according to the present invention is capable of heating biomass without being affected by low-temperature corrosion, and more efficiently embrittles so that it can be easily pulverized and combusted by a pulverizer. There is an effect.

FIG. 1 is a schematic diagram illustrating a schematic configuration of an embodiment of a power generation system. FIG. 2 is a schematic diagram showing a part of the schematic configuration of the biomass pretreatment unit. FIG. 3 is a schematic configuration diagram of a biomass supply tank and a feeder of the biomass pretreatment unit. FIG. 4 is a graph showing the relationship between the temperature of biomass and the ratio of each component. FIG. 5 is a graph showing the relationship between the grinding power ratio and the grinding time to a predetermined particle size. FIG. 6 is a schematic diagram illustrating a schematic configuration of another embodiment of the power generation system.

  Hereinafter, the present invention will be described in detail with reference to the drawings. In addition, this invention is not limited by this Example, Moreover, when there exists multiple Example, what comprises combining each Example is also included. In addition, constituent elements in the following embodiments include those that can be easily assumed by those skilled in the art or those that are substantially the same.

  Exemplary embodiments of a preprocessing unit and a power generation system using the preprocessing unit according to the present invention will be described below in detail with reference to the accompanying drawings. In addition, this invention is not limited by this embodiment.

  FIG. 1 is a schematic diagram illustrating a schematic configuration of an embodiment of a power generation system.

  A power generation system 10 shown in FIG. 1 uses a fine powder obtained by pulverizing biomass and a fossil fuel such as coal or oil as a fuel for combustion, collects heat generated by the combustion, and generates electricity using the recovered heat. It is a power generation system that can.

  A power generation system 10 shown in FIG. 1 includes a biomass supply device 11 that supplies biomass, a boiler 30 that recovers heat generated by burning biomass and fossil fuel supplied from the biomass supply device 11, and a boiler 30. And a power generation device 60 that generates power using the heat generated in step.

  Here, biomass is defined as organic resources derived from renewable organisms, excluding fossil resources. For example, thinned wood, waste wood, driftwood, grass, waste, sludge, tires, and recycled fuel (pellets and chips) using these as raw materials are not limited to those presented here.

  The biomass supply device 11 is a device that heats the biomass 140 in the range of the non-carbonization temperature, then pulverizes it, and supplies the pulverized biomass to the boiler 30, and a biomass pretreatment unit (hereinafter referred to as “pretreatment unit”) 19 , An air supply pipe 21, a crusher (mill) 26, a powder separation device 27, and a supply pipe 28.

  The pre-processing unit 19 is a unit that pre-processes biomass and then supplies it to the crushing device 26. The storage silo 20, the dispensing conveyor 22, the transport conveyor 23, the biomass supply tank 24, and the feeder 25 are provided. Have. The storage silo 20 is a device that can store a predetermined amount of biomass. The storage silo 20 supplies the stored biomass 140 to the delivery conveyor 22 by a predetermined amount. The payout conveyor 22 and the transfer conveyor 23 are both transfer mechanisms that transfer the biomass 140. In addition, although it was set as the conveyor in this embodiment, as a conveyance mechanism of biomass 140, various mechanisms can be used. The payout conveyor 22 transports the biomass 140 supplied from the storage silo 20 to the transport conveyor 23. The conveyor 23 supplies the biomass 140 supplied from the payout conveyor 22 to the biomass supply tank 24.

The biomass supply tank 24 temporarily stores the biomass 140 supplied from the transport conveyor 23. The biomass supply tank 24 supplies the stored biomass 140 to the feeder 25. The feeder 25 conveys the biomass 140 supplied from the biomass supply tank 24 and supplies it to the crushing device 26.
The heating means is a heating mechanism that heats the biomass by indirect heating using the steam 203a in the biomass supply tank 24 and heats the biomass by direct heating using a part 150b of the boiler exhaust gas 150 in the feeder 25. is there. The configuration of the heating means will be described later.

  The description of the configuration of the biomass supply apparatus 11 will be continued. The air supply pipe 21 is a pipe that supplies air to each part of the biomass supply apparatus 11. The air supply pipe 21 is connected to each part for supplying air of the boiler 30 and supplied with air 148. The air supply pipe 21 is connected to the crusher 26 and the supply pipe 28 and supplies air 148 to each of them. Further, the air supply pipe 21 is provided with a valve 70 in a pipe connected to the crushing device 26, and a valve 72 is provided in a pipe connected to the supply pipe 28. The amount of air 148 supplied to each part can be adjusted by adjusting the opening / closing and opening of the valves 70 and 72.

  The pulverizer 26 is a pulverizer for pulverizing biomass, and pulverizes the biomass 140 supplied from the feeder 25 into fine powder. In addition, an air supply pipe 21 is connected to the pulverizer 26, and the crushed biomass 140 is conveyed by the force of air 148 supplied from the air supply pipe 21. That is, the biomass 140 pulverized by the pulverization device 26 moves through the pipe 108 by air conveyance and is conveyed to the powder separation device 27. The powder separation device 27 includes a bag filter and a cyclone, and separates and classifies the biomass 140 that passes therethrough. The powder separation device 27 supplies the biomass 140 having a certain size or more out of the crushed biomass 140 that passes through the supply pipe 28 as the coarse powder 142. In addition, the powder separator 27 supplies the biomass 140 having a smaller size than the fixed biomass 140 as fine powder 144 to the electric dust collector 55 side, which will be described later, through the pipe 109 and traps it in the electric dust collector 55. Collect. Note that the biomass 140 supplied to the powder separation device 27 is substantially all coarse powder 142. For example, the powder separation device 27 sends a wind blown up to the biomass 140 by a cyclone, and supplies the biomass 140 having a certain size or more falling as a coarse powder 142 to the supply pipe 28 even if the wind is blown. The blown-up biomass 140 having a smaller size is supplied as fine powder 144 to an exhaust gas pipe 50 (immediately before the electric dust collector 55) for supplying air to the electric dust collector 55. The supply pipe 28 supplies the coarse powder 142 and air 148 supplied from the powder separation device 27 to the biomass combustion burner 34 of the boiler 30. The air 148 supplied from the air supply pipe 21 to the supply pipe 28 is primary air.

  Next, the boiler 30 is a conventional boiler, and has a boiler body 31 capable of burning biomass and fossil fuel. The boiler main body 31 has a hollow shape and is installed in the vertical direction, and a combustion device 32 is provided at the lower part of the furnace wall constituting the boiler main body 31. The combustion device 32 has a plurality of fossil fuel combustion burners 33 mounted on the furnace wall and a plurality of biomass combustion burners 34. In the present embodiment, four or eight combustion burners 33 for fossil fuel are arranged along the circumferential direction and arranged in three to six stages in the vertical direction. On the other hand, the biomass combustion burner 34 is arranged below the plurality of fossil fuel combustion burners 33, and four or eight disposed along the circumferential direction are arranged in one stage in the vertical direction. . The arrangement relationship between the combustion burner 33 for fossil fuel and the combustion burner 34 for biomass may be upside down. In each combustion burner 33, 34, the number in the circumferential direction is not limited to four, and the number of stages is not limited to four or one stage. Furthermore, you may arrange | position so that each combustion burner 33 and 34 may oppose.

  The combustion burner 33 for fossil fuel is connected to a pulverized coal supply unit 35 via a supply pipe 36 and to a fuel oil (or fuel gas) supply part 37 via a supply pipe 38. In this case, pulverized coal or fuel oil can be supplied as the fossil fuel. On the other hand, the biomass combustion burner 34 is connected to a supply pipe 28 from the biomass supply device 11.

  The combustion device 32 has an air supply pipe 39 that can supply combustion air to each of the combustion burners 33, 34. The air supply pipe 39 is provided with a blower 40 at the base end portion, and has a distal end portion. Is connected to a wind box 41 provided on the outer peripheral side of the boiler body 31. Therefore, the air supplied to the wind box 41 can be supplied to the combustion burners 33 and 34.

  The boiler body 31 has a flue 42 connected to the upper portion thereof, and the superheaters 43 and 44, the reheaters 45 and 46, and the nodes for recovering the heat of the exhaust gas as a convection heat transfer section are connected to the flue 42. Charcoal units 47, 48, and 49 are provided, and heat exchange is performed between the exhaust gas generated by the combustion in the boiler body 31 and water.

  The flue 42 is connected to an exhaust gas pipe 50 through which the exhaust gas 150 subjected to heat exchange is discharged downstream. The exhaust gas pipe 50 is provided with an air heater 51 between the air supply pipe 39 and performs heat exchange between the air 148 flowing through the air supply pipe 39 and the exhaust gas 150 flowing through the exhaust gas pipe 50, and the combustion burner 33, It is desirable to raise the temperature of combustion air supplied to 34 to a range of 200 to 300 ° C.

  The air supply pipe 39 is branched from a position downstream of the air heater 51, and the air supply pipe 21 is provided. The air supply pipe 21 is equipped with a dust removing device 52 capable of removing particulate matter such as dust and dust, and a blower 53 capable of boosting high-temperature air. Air heated by an air heater 51 to 200 to 300 ° C. It can be supplied to the supply pipe 28 of the biomass supply apparatus 11.

  The exhaust gas pipe 50 is located upstream of the air heater 51 and is provided with a selective reduction catalyst 54, and is located downstream of the air heater 51 and is provided with an electric dust collector 55, an induction blower 56, and a desulfurization device 57. A chimney 58 is provided at the downstream end.

  A pipe 73 is connected upstream of the electric dust collector 55 of the exhaust gas pipe 50. The pipe 73 is connected to the supply pipe 28 and a pipe between the crushing device 26 and the powder separation device 27. In the pipe 73, a valve 74 is arranged between a connection portion with the upstream side of the electric dust collector 55 and a connection portion with the supply pipe 28, and the connection portion with the upstream side of the electric dust collector 55, the pulverizer 26 and the powder separation. A valve 76 is disposed between the pipe connecting the apparatus 27 and the connecting part. A part of the exhaust gas 150 flowing through the exhaust gas pipe 50 is supplied to the pipe 73, and is supplied as the carrier gas 150 a from the pipe 73 to the supply pipe 28 and the pipe between the crushing device 26 and the powder separation device 27. . Further, the valve 74 adjusts the supply amount of the carrier gas 150 a from the pipe 73 to the supply pipe 28. Further, the valve 76 adjusts the supply amount of the carrier gas 150 a from the pipe 73 to the pipe between the pulverizer 26 and the powder separator 27.

  The power generation device 60 is a conversion mechanism that converts thermal energy into electricity. The piping unit 62 is a pipe that connects the superheaters 43 and 44 and the reheaters 45 and 46 of the boiler 30 to the power generation device 60, and steam that is superheated by the superheaters 43 and 44 and the reheaters 45 and 46. Is sent to the power generator 60, and the steam exchanged by the power generator 60 is sent to the superheaters 43 and 44 and the reheaters 45 and 46. The power generation device 60 converts thermal energy extracted from the steam superheated by the superheaters 43 and 44 and the reheaters 45 and 46 into electricity. For example, the power generation device 60 includes a turbine, rotates the turbine using the energy of superheated steam, and extracts electric power.

  As described above, when the power generation system 10 drives the blower 40 and sucks the air 148 in the boiler 30, the air 148 is heated by the air heater 51 through the air supply pipe 39 and then burned through the wind box 41. It is supplied to the burners 33 and 34. Further, pulverized coal or fuel oil as fossil fuel is supplied to the combustion burner 33 for fossil fuel through the supply pipes 36 and 38, and biomass from the biomass supply apparatus 11 is supplied to the combustion burner for biomass through the supply pipe 28. 34.

  Then, the combustion burner 33 for fossil fuel injects combustion air and fossil fuel into the boiler body 31 and ignites at the same time, and the combustion burner 34 for biomass converts the combustion air and fine powder of biomass into the boiler body 31. It ignites at the same time as it is injected. In the boiler body 31, combustion air, fossil fuel, and biomass are burned to generate a flame. When a flame is generated in the lower part of the boiler body 31, the combustion gas rises in the boiler body 31 and is discharged to the flue 42.

  At this time, water (boiler feed water) supplied from a water supply pump (not shown) is preheated by the economizers 47, 48, and 49 and then supplied to a steam drum (not shown) to each water pipe (not shown) on the furnace wall. While being supplied, it is heated to become saturated steam and fed into a steam drum (not shown). Further, saturated steam of a steam drum (not shown) is introduced into the superheaters 43 and 44 and is heated by the combustion gas. The superheated steam generated by the superheaters 43 and 44 passes through the piping unit 62 and is supplied to the power generation device 60. Further, the steam taken out in the middle of the expansion process in the power generation device 60 passes through the piping unit 62 and is introduced into the reheaters 45 and 46, is overheated again, passes through the piping unit 62, and returns to the power generation device 60. It is. In addition, although the boiler main body 31 was demonstrated as a drum type | mold (steam drum), it is not limited to this structure.

  Thereafter, the exhaust gas 150 that has passed through the economizers 47, 48, and 49 of the flue 42 is removed of harmful substances such as NOx by the selective reduction catalyst 54 in the exhaust gas pipe 50, and the particulate matter is removed by the electric dust collector 55. After being removed and the sulfur content removed by the desulfurization device 57, it is discharged from the chimney 58 into the atmosphere.

Next, the heating means in the biomass supply tank 24 and the feeder 25 constituting the pretreatment unit 19 will be described with reference to FIGS. 1 to 3.
Here, FIG. 2 is a schematic diagram illustrating a part of a schematic configuration of the pretreatment unit, and FIG. 3 is a schematic configuration diagram of a biomass supply tank and a feeder of the biomass pretreatment unit.
First, the pretreatment unit 19 includes the storage silo 20, the dispensing conveyor 22, the transfer conveyor 23, the biomass supply tank 24, and the feeder 25 described above, and the biomass in the biomass supply tank 24 and the feeder 25. It has a heating means for heating.

  The feeder 25 is a screw feeder disposed between the biomass supply tank 24 and the pulverizer 26, and includes a rotating unit (not shown), a guide tube that covers the outer periphery of the rotating unit and holds biomass, and a rotating unit. A drive source for rotation. The rotating part is a screw having a screw groove formed on the outer periphery, and conveys the biomass 140 in one direction from the supply part to the outlet part by rotating. The rotating part has a hollow shape.

The biomass heating means will be described with reference to FIG.
As shown in FIG. 2, steam (before heating) 203 a is introduced into the pipe in the biomass supply tank 24 that temporarily stores the biomass 140 and supplies it to the feeder 25, and indirectly stores the biomass 140 stored therein. Is heating up. In FIG. 2, reference numerals are shown.
Further, a part 150b of the boiler exhaust gas 150 is supplied to the feeder 25, and the biomass supplied to the crushing device 26 is directly heated.
In FIG. 2, the main part of FIG. 1 is extracted and includes a biomass supply tank 24, a feeder 25, a powder separation device 27, and a boiler 30.
In FIG. 2, reference numeral 31 a is a furnace, 31 b is a superheater, a boiler unit in which a reheater is omitted, 203 b is steam (after heating), 201 is main steam from the heat exchanging part 31 of the boiler 30, and 202 is high temperature. Reheat steam. Reference numeral 203 is a low-temperature reheat steam, 204 is boiler feed water, L ₁₁ is a steam supply line, L ₁₂ is a steam return line, L ₂₁ is an exhaust gas supply line, and L ₂₂ is an exhaust gas return line.

Heating in the biomass supply tank 24 uses steam (a part of the low-temperature reheated steam 203 in this embodiment) 203a supplied from the outside as a heat medium, and supplies it into the steam pipe, The biomass 140 stored in is indirectly heated.
Here, the reason why the steam 203a is used as the heating medium in the present invention is to avoid low-temperature corrosion as in the case of using the exhaust gas 150. That is, in order to indirectly heat the biomass by introducing the exhaust gas 150 into the pipe, when the sulfur (S) content present in the exhaust gas 150 is heat-exchanged with the low-temperature biomass, it becomes 150 ° C. or less in the pipe, This is because low-temperature corrosion occurs, which is not preferable.
The steam that has contributed to the indirect heating of the biomass is reused by returning it to the low-temperature reheat steam 203 side.

The direct heating in the feeder 25 uses a part 150b of the boiler exhaust gas 150 supplied from the outside.
A part 150b of the exhaust gas is supplied to the inside of the feeder 25 from the biomass outlet portion (pulverization apparatus) side of the feeder 25, and the biomass is heated while facing and opposed to the biomass pushed out by a screw (not shown).
The feeder 25 is connected to the supply line 24b from the biomass supply tank 24 on the base end portion 25a side (biomass supply side), and on the tip end portion 25b side (biomass discharge side) of the feeder 25, the powder device 26. It is connected to a supply line 26a for supplying biomass.

  In the present invention, the biomass is preheated to a predetermined temperature (150 ° C.) in the biomass supply tank 24, and the preheated biomass is gradually heated inside the main body of the feeder 25 to be predetermined brittle. The temperature is set.

FIG. 3 is a schematic configuration diagram of a biomass supply tank and a feeder of the biomass pretreatment unit. In FIG. 3, the biomass code is changed to 140 and 140 </ b> A to 140 </ b> C according to the temperature state of the biomass 140.
As shown in FIG. 3, the biomass 140 when supplied to the biomass supply tank 24 is at room temperature.
Next, the stored biomass is indirectly heated (primary heating) by the steam 203a supplied into the steam pipe 24a in the biomass supply tank 24. The temperature (T ₁ ) of the preheated biomass 140A when discharged from the biomass supply tank 24 through the supply line 24b is 150 ° C. or higher.
This is the direct heating by the part 150b of the boiler exhaust gas that is introduced opposite to the feeder 25 that feeds the biomass to the pulverizer 26, so that the acid dew point may be reached when the internal temperature is about 150 ° C. or lower. This is to avoid low temperature corrosion in the feeder 25.
Therefore, the preheating biomass 140A introduced into the feeder 25 is indirectly heated with steam so that the temperature (T ₁ ) of the preheated biomass 140A is 150 ° C. or higher.

Thus, the following effects are produced by introducing part 150b of the boiler exhaust gas so as to face the biomass 140.
By making the introduction of the exhaust gas in the direction opposite to the biomass transport direction, heat exchange can be performed more efficiently than in the same direction.
That is, it is possible to reduce the amount of exhaust gas to be supplied for the same amount of exchange heat.
In addition, when the exhaust gas is introduced facing the biomass temperature, the biomass temperature at the feeder outlet approaches the exhaust gas supply temperature. Therefore, the biomass temperature at the feeder outlet can be easily adjusted by adjusting the exhaust gas supply temperature.

Next, the supplied preheated biomass 140 </ b> A is directly heated by a part 150 b of the exhaust gas introduced to be opposed to be heated biomass 140 </ b> B inside the feeder 25. The lower limit temperature (T ₂ ) of the heated biomass 140B is set to 150 to 200 ° C. or higher.
The reason why the lower limit temperature (T ₂ ) is set to 150 to 200 ° C. or more is to avoid low temperature corrosion inside the feeder 25 and to promote the embrittlement of biomass.

  Biomass can be expected to become brittle at temperatures of 150 ° C. or higher, and becomes pulverizable at a level that can be mixed and pulverized with coal at temperatures of 250 to 300 ° C. or higher. By generating, the calorie | heat amount of biomass will fall.

Moreover, when it heats at the temperature of 250-300 degreeC, pyrolysis of biomass advances, pyrolysis gas and tar generate | occur | produce and adhere to the inside of the feeder 25, Therefore The heating temperature inside the feeder 25 is at least 150-200 degreeC or more. In order to prevent tar condensation, the heating is preferably performed at 250 to 300 ° C. or less.
Furthermore, in order to determine the heating temperature of biomass from the balance of the amount of heat reduction of biomass due to heating and the reduction of mill power due to embrittlement, it is preferable to heat at a temperature of 200 to 250 ° C.

As a result, the temperature (T ₃ ) of the heated biomass 140C in the supply line 26a when heated inside the feeder 25 and delivered to the crushing device 26 is controlled to be 200 to 250 ° C.
The heated biomass 140C is pulverized by the pulverizing device 26 and supplied to the powder separation device 27 side shown in FIG. 1 as pulverized biomass 140D.

  Moreover, since the exhaust gas 150c after biomass heating used for heating contains the combustible part derived from the biomass by heating, the combustible part can be effectively used by supplying it to the boiler furnace. At this time, the exhaust gas 150c after heating the biomass may be mixed with the combustion air of the boiler 50 and used as the combustion air. It is also possible to return to the exhaust gas treatment facility.

The heating means according to the present embodiment is configured as described above, and is two-stage heating including indirect heating (primary heating) in the biomass supply tank 24 and direct heating (secondary heating) in the feeder 25. .
When preheated by indirect heating and supplied to the feeder 25, the temperature of the biomass in the feeder 25 becomes 150 ° C or higher by setting the preheated biomass 140A to a lower limit value of 150 ° C. Low temperature corrosion due to the sulfur (S) content in the part 150b of the exhaust gas facing each other can be avoided.

That is, by preheating biomass to 150 ° C. or higher, the lower limit value of the temperature inside the feeder 25 becomes 150 ° C., and low temperature corrosion inside the feeder 25 is avoided.
And since the temperature of the gas at the time of directly heating with the part 150a of boiler exhaust gas in the feeder 25 is 300-350 degreeC, embrittlement of the biomass 140 advances and a grinding | pulverization becomes easy. As a result, the biomass can be combusted more efficiently in the boiler 30.

  The 1st and 2nd temperature measurement parts 121 and 122 are installed in two places with the base end part 25a side and the front-end | tip part 25b side of the feeder 25, and the atmospheric temperature of the biomass 140 of the said part, or the temperature of biomass itself is set. It is preferable to use a means for measuring. The first and second temperature measuring units 121 and 122 send the measured temperature of the biomass 140 to the control unit 130.

Based on the measurement results of the first and second temperature measurement units 121 and 122, the control unit 130 generates steam 203a that is a heat source for indirect heating supplied to the biomass supply tank 24 and exhaust gas that is a heat source for direct heating. The operation of the part 150b is controlled.
As shown in FIG. 3, the flow rate is adjusted by adjusting a valve 123 interposed in a gas supply line L ₂₁ for supplying a part 150 b of exhaust gas so that the temperature becomes a predetermined temperature.
In addition, the control unit 130 controls operations of various other mechanisms.

The pretreatment unit 19 is configured as described above, and performs preheating of the biomass in the biomass supply tank 24 by the indirect heating means and heating for embrittlement of the biomass in the feeder 25 by the direct heating means.
Further, in the pretreatment unit 19, the control unit 130 controls the operation of the heating unit based on the temperature measurement results in the first and second temperature measurement units 121 and 122, and controls the temperature of the biomass 140. Thus, the temperature of the discharged biomass 140 is discharged within a certain range, specifically, in a state of the non-carbonizing temperature range.

  Here, the range of the non-carbonizing temperature is a temperature at which the biomass 140 becomes brittle in a state where the biomass 140 is not carbonized and the discharged tar becomes a certain concentration or less.

  Here, FIG. 4 is a graph showing the relationship between the biomass temperature and the ratio of each component, and FIG. 5 is a graph showing the relationship between the pulverization power ratio and the pulverization time up to a predetermined particle size. FIG. 4 shows the relationship of the weight ratio of each component when the vertical axis is weight ratio [%] and the biomass is heated to each temperature (before heating, 150 ° C., 200 ° C., 250 ° C., 300 ° C.). . In FIG. 5, the vertical axis represents the estimated pulverization power ratio up to a predetermined particle size in the mill (pulverizer), and the horizontal axis represents the pulverization time [s] to the predetermined particle size in the ball mill (pulverizer). FIG. 4 shows an estimated pulverization power ratio and a ball mill (pulverizer) when the wood pellet A is heated to a raw state (before heating), 150 ° C., 200 ° C., 250 ° C., and 300 ° C. The result of having measured the relationship with the grinding | pulverization time to the predetermined particle size in ()) is shown. For comparison, FIG. 5 also shows an estimated crushing power ratio for each of the unheated wood chip A, wood chip B, and wood pellet B, and the grinding time to a predetermined particle size in a ball mill (grinding device). The result of measuring the relationship with is also shown.

  As shown in FIG. 4, the biomass has a component ratio that varies depending on the temperature at which it is heated, and tar is deposited when it exceeds a certain temperature. In addition, the biomass becomes brittle as it is heated to a higher temperature. Specifically, when wood pellets are heated, the grinding time to a predetermined particle size in a ball mill (grinding device) becomes shorter than the grinding time of wood pellets that are not heated. Furthermore, if the temperature at which the wood pellets are heated is increased, the pulverization time is further shortened.

  For example, as shown in FIG. 5, when the wood pellet A is heated to 150 ° C., the pulverization time up to a predetermined particle size in a ball mill (pulverization apparatus) becomes shorter than the pulverization time of the wood pellet B that is not heated. Furthermore, if the temperature at which the wood pellet A is heated to 200 ° C. and 250 ° C. is increased, the pulverization time is further shortened. Here, since the estimated pulverization power ratio up to a predetermined particle size in the mill (pulverization apparatus) is proportional to the pulverization time, the pulverization time is shortened, so that the power required for pulverization is also reduced. As mentioned above, biomass becomes easy to grind, so that temperature is raised. In addition, the range of non-carbonization temperature, that is, the optimum temperature at which biomass is easily pulverized while suppressing the influence of tar, is a temperature range and temperature that differ depending on the type of biomass. Here, the temperature range of the biomass is set to a temperature of 150 ° C. or more and 250 ° C. or less, so that the tar discharged is more reliably reduced, for example, a generation amount of 20% or less of the total amount of biomass). The biomass can be easily pulverized while suppressing the influence of tar. Note that the biomass temperature range of 150 ° C. or more and 250 ° C. or less is a temperature at which tar generation can be more reliably reduced and the pulverization time can be sufficiently shortened.

  Based on the above relationship, the pretreatment unit 19 heats the biomass 140 in a non-carbonization temperature range in which the biomass 140 becomes brittle and the discharged tar is at a certain concentration or less.

  In the example shown in FIGS. 4 and 5, the pretreatment unit 19 heats the biomass 140 to a temperature between 150 ° C. and 250 ° C. Thereby, the pre-processing unit 19 can make it easy to grind | pulverize biomass, suppressing the influence in which volatile gas, such as tar, is discharged | emitted, and also suppressing generation | occurrence | production of tar. The pretreatment unit 19 makes the biomass easy to grind and discharges (supplies) the biomass from the discharge port of the feeder 25 to the grinder 26. The biomass conveyed to the pulverizing device 26 is pulverized by the pulverizing device 26. At this time, since the biomass 140 heated to the non-carbonizing temperature in the pretreatment unit 19 is supplied to the pulverizer 26, the pulverizer 26 can be pulverized to a predetermined particle size in a short time with less power. Further, since the pretreatment unit 19 heats the biomass 140 to the range of the non-carbonization temperature, the tar generated by heating can be reduced to a certain concentration or less (that is, the tar is prevented from being discharged more than a certain concentration). It is possible to suppress the transfer efficiency of biomass from being reduced or adhering to each part of the pretreatment unit 19 due to the generation of tar. From the above, the pretreatment unit 19 and the biomass supply apparatus 11 can efficiently pulverize biomass. In addition, since only a heating mechanism is provided around or inside the pretreatment unit 19, the apparatus configuration can be simplified. Furthermore, since generation | occurrence | production of volatile gases, such as tar, can be suppressed, the generated tar can be appropriately burned with the boiler 30, the adhesion of tar to an apparatus can be suppressed, apparatus maintenance, etc. Can also be simplified. Here, when the temperature of the biomass is 150 ° C. or higher and 250 ° C. or lower, tar generation can be more reliably suppressed, and the above effect can be obtained more reliably. Thus, pulverization can be improved while suppressing the influence of discharge of volatile gases such as tar.

  Moreover, the biomass 140 can be dried by heating the biomass 140 to the range of the non-carbonization temperature in the pretreatment unit 19. Thereby, the pretreatment unit 19 can put the biomass in a dry state when it is put into the crushing device 26, and can omit the drying in the crushing device 26. Thereby, various air can be used as the air supplied to the pulverizer 26, and air at normal temperature can also be used.

  The biomass heating means only needs to be able to heat the biomass to the range of the non-carbonization temperature, and the heating means itself may be at a temperature higher than the non-carbonization temperature.

  In addition, as the heating medium of the pretreatment unit 19, the indirectly heated steam 203 a uses a part of the low-temperature reheated steam 203 and returns again after contributing to indirect heating. Efficiency can be increased, and the generated heat can be effectively utilized.

  In addition, the control unit 130 performs heating operation of the heating unit based on the measurement results of the first and second temperature measurement units 121 and 122 so that the biomass in the vicinity of the outlet of the feeder 25 becomes the non-carbonization temperature, The biomass transport operation by the feeder 25 is controlled. Specifically, the heating amount by the heating means (for example, the supply amount of exhaust gas), the biomass conveyance speed by the feeder 25, and the like are controlled. The biomass conveyance speed is controlled by changing the rotation speed of the rotating unit and the angle of the screw of the rotating unit. Further, the control unit 130 calculates in advance an experiment or the like the relationship between the target non-carbonization temperature and the temperature measured by the temperature measurement unit 120 at the non-carbonization temperature, and the calculated result and the temperature measurement It is preferable to control the operation of each unit based on the temperature measured by the unit 120. Thereby, biomass can be appropriately made into the non-carbonization temperature. Note that the temperature measurement position by the temperature measurement unit 120 is preferably in the vicinity of the exit of the region where the heating means is disposed as in this embodiment, but the present invention is not limited to this. In addition, without providing the temperature measurement unit 120, the heating operation may be controlled based on the set conditions so that the biomass is brought to a non-carbonization temperature.

  As described above, according to the present invention, pulverization is improved by two-stage heating pretreatment of biomass, and reduction of pulverization power in the pulverizer and mixed pulverization with coal can be expected. Moreover, since drying at the time of grinding | pulverization in a grinding | pulverization apparatus becomes unnecessary, normal temperature air can be used as gas for grinding | pulverization, and safety | security improves. Moreover, in the case of primary heating, since it is indirect heating with steam, low-temperature corrosion as in the case of using exhaust gas can be avoided. In addition, by supplying the primary heating to the feeder at 150 ° C. or higher, low temperature corrosion is avoided and good embrittlement is possible even if direct heating using exhaust gas is performed in the feeder that is secondary heating. .

  Next, the pre-processing unit and biomass storage unit of other embodiment are demonstrated using FIG. Here, FIG. 6 is a schematic diagram showing a schematic configuration of another embodiment of the power generation system. A power generation system 240 shown in FIG. 6 is a biomass / coal mixed combustion power generation system. That is, FIG. 6 is a power generation system that also shows a schematic configuration of a coal supply apparatus. In FIG. 6, the illustration of the power generation device is omitted.

  As shown in FIG. 6, the power generation system 240 stores the biomass and crushes the pretreatment unit 19 that is heated to the non-carbonization temperature in two stages before discharge and the biomass heated to the non-carbonization temperature in the pretreatment unit 19. Biomass pulverizer 26, piping 249 for supplying biomass pulverized by pulverizer 26 to combustion burner 34, coal pulverizers 252a and 252b including hoppers 251a and 251b for receiving coal 250, and coal pulverizer 252a , 252b, and a pipe 253 for supplying the coal powder obtained in 252b to the combustion burner 33. Further, the power generation system 240 has a configuration similar to that of the boiler 30 of FIG. It has each part.

  The boiler body 31 is provided with an air heater (AH) 262 in the middle of the flue provided at the furnace outlet of the furnace body, and the combustion exhaust gas passing through the air heater 262 is discharged from an ash collector or the like. It is released into the atmosphere through an exhaust gas treatment facility (not shown). High-temperature air 264 generated by heating the outside air 263 by the air heater 262 is supplied to the coal pulverizers 252a and 252b and used for drying the coal 250. A part 265 of the combustion exhaust gas is supplied to the pulverizing device 26 by the induction fan 266 and used for classification of biomass.

  Thus, according to the power generation system of biomass / coal co-firing, biomass crushing is improved by providing the biomass crushing apparatus provided with the biomass pretreatment unit according to the present invention. As a result, the biomass is pulverized and the mixed combustion of the coal with the pulverized coal from the coal pulverizer is good and efficient combustion in the boiler furnace becomes possible.

DESCRIPTION OF SYMBOLS 10 Power generation system 11 Biomass supply apparatus 19 Biomass pre-processing unit 20 Storage silo 21 Air supply piping (air supply system)
22 Discharge conveyor 23 Conveyor 24 Biomass supply tank 25 Feeder 26 Crusher (mill)
27 Powder Separator 28 Supply Piping 30 Boiler 31 Boiler Body 32 Combustion Device 33 Combustion Burner for Fossil Fuel 34 Combustion Burner for Biomass 39 Air Supply Piping 42 Flue 51 Air Heater 52 Dust Removal Device 53 Blower 60 Power Generation Device 62 Piping Unit 121 First temperature measurement unit 122 Second temperature measurement unit 130 Control unit

Claims (6)

A biomass pretreatment unit for supplying biomass to a pulverizer for pulverizing biomass,
A biomass supply tank for supplying the biomass to a feeder;
Indirect heating means for preheating biomass by indirectly heating the biomass supply tank;
A feeder for supplying preheated biomass preheated and heated in the biomass supply tank to a pulverizer;
A biomass pretreatment unit comprising: a direct heating means that introduces boiler exhaust gas from the end of the feeder on the pulverizer side and embrittles the preheated biomass while heating it to a predetermined temperature in the feeder. . In claim 1,
The biomass pretreatment unit characterized in that the direct heating temperature in the feeder is in the range of the non-carbonizing temperature of the biomass. In claim 1 or 2,
The biomass pretreatment unit, wherein the indirect heating means is low-temperature reheat steam. In any one of Claims 1 thru | or 3,
The biomass pretreatment unit, wherein the direct heating means is exhaust gas from a boiler. In any one of Claims 1 thru | or 4,
A biomass pretreatment unit for supplying an exhaust gas after heating biomass that contributes to heating in the feeder to the boiler furnace. A biomass crusher comprising the biomass pretreatment unit according to any one of claims 1 to 5;
A coal crusher for crushing the coal raw material;
A biomass-coal co-firing system comprising a biomass powder pulverized by a biomass pulverizer and a boiler furnace to which the coal powder pulverized by the coal pulverizer is supplied.

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