JP2016035346A - Biomass fuel mixed combustion method and biomass fuel mixed combustion system - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a biomass fuel mixed combustion method and a biomass fuel mixed combustion system for achieving the stability and improvement of combustion efficiency in a power generation system intended at various biomass fuels.SOLUTION: A mixed combustion method for biomass fuel supplied to a boiler 58 in a biomass power generation facility, comprises: calculating a quantity of steam generated by the boiler 58 to correspond to a target power generation amount of the biomass power generation facility; calculating a fuel input amount of the biomass fuel to correspond to combustion energy in the boiler 58 necessary for the steam quantity; forming the biomass fuel by a plurality of fractional fuels (fuels 18A to 18D, fuels 42A to 42D) having different physical quantities affecting a combustion state; calculating a mixture rate of each fractional fuel on the basis of management information containing information on a secular change in the physical quantity of each fractional fuel; and forming the biomass fuel by mixing the fractional fuels on the basis of the mixture rate.SELECTED DRAWING: Figure 1

Description

  The present invention relates to a fuel co-firing method in a biomass power plant, and more particularly to a co-firing method and a co-firing system for a plurality of biomass fuels in order to ensure an efficient and stable boiler combustion state.

  The use of renewable energy is increasing in importance due to the recent energy situation and social demands. Although policies such as feed-in tariffs for renewable energy have been boosted, demand for improved power generation efficiency is high due to the impact of the business balance due to an increasing trend in fuel costs.

  On the other hand, conventional biomass power generation plants mainly employ power generation by single fuel, two kinds of mixed fuels, or mixed combustion of them and coal. Patent Document 1 discloses a technique for increasing the power generation efficiency of a boiler, including a biomass crushing means and a biomass heating means using boiler combustion exhaust gas downstream from the economizer, with regard to a plant operation method related to power generation efficiency improvement. ing. Patent Document 2 discloses a technology that facilitates combustion by adjusting the particle size of the fuel supplied to the boiler, which includes a granular material separation device for selecting the particle size in the biomass fuel conveyance path after pulverization. doing.

  Patent Document 3 discloses an operation method in which powder charcoal is supplied as an auxiliary combustion material when the amount of steam is reduced in order to maintain a constant steam flow rate in a system that generates power by burning a bark material and rotating a steam turbine. Patent Document 4 discloses a method for safely managing charcoal and coal in a mixed combustion system by drying the charcoal with the heat of oxidation of the coal to prevent a decrease in combustion efficiency and suppressing an increase in the temperature of the coal. Yes.

JP 2014-37896 A JP 2014-37897 A JP 2003-329203 A JP 2008-180395 A

  In recent years, biomass fuel costs have been increasing, and there is a high demand for securing fuel at a low cost. For this reason, a technique for procuring various fuels and storing and burning them appropriately according to the fuel form is required. In addition, the above-mentioned patent document discloses a method for improving the combustion efficiency for a single fuel or a small number of fuels, but does not disclose an appropriate storage method and operation method for various fuels.

  The present invention is to solve the above-mentioned problems, and in a power generation system for various biomass fuels that contributes to a reduction in fuel procurement costs, biomass fuel co-firing to stabilize and improve combustion efficiency It is an object to provide a method and a biomass fuel co-firing system.

In order to achieve the above object, a biomass fuel co-firing method according to the present invention is, firstly, a method of co-firing biomass fuel supplied to a boiler of a biomass power generation facility, which corresponds to a target power generation amount of the biomass power generation facility. Calculating the amount of steam generated by the boiler, calculating the fuel input amount of the biomass fuel corresponding to the combustion energy in the boiler necessary for this, a plurality of different physical quantities that affect the combustion state of the biomass fuel The mixing ratio of each separated fuel is calculated based on management information including information on the change in the physical quantity of each sorted fuel over time, and the separated fuel is mixed based on the mixing ratio. It is characterized by forming.
By the above method, it is possible to stably generate electric power even with various biomass fuels having different physical quantities related to combustion and changes with time.

Secondly, the management information includes information on the storage amount of each separated fuel, information on the procurement plan time, and information on the cost, and adjusting the fuel input amount of each separated fuel based on these information. Features.
By the above method, the power generation cost and the profit rate in the biomass power generation facility can be optimized.

Third, when the power generation amount of the biomass power generation facility is lower than the target power generation amount, the biomass fuel has a higher mixing ratio of the fractionated fuel with higher combustion efficiency in the biomass fuel, and the biomass power generation facility When the power generation amount becomes higher than the target power generation amount, the biomass fuel is increased in the mixing ratio of the fractional fuel on the forward side having low combustion efficiency.
Since the power generation amount can be suppressed to a certain fluctuation range by the above method, the power generation amount can be stabilized even if the heat generation amount of each biomass fuel is uneven.

Fourth, the fractionated fuel is agitated and mixed before being supplied to the boiler.
By the above method, it is possible to stabilize the amount of steam generated by the boiler, that is, the amount of power generation, by suppressing combustion unevenness in the boiler.

Fifth, the separated fuel may be stored separately for the different physical quantities or for each kind of the separated fuel.
By the above method, it is possible to easily manage the separated fuel.

Sixth, the physical quantity includes at least a particle size, a bulk density, a calorific value, and a moisture content of the fractionated fuel.
Since the combustion efficiency of each fractionated fuel is stabilized by the above method, the combustion efficiency of the mixed biomass fuel can be easily adjusted.

Seventhly, among the fractionated fuels, a forward fractional fuel having a high water absorption property is disposed indoors, and a forward fractional fuel having a low water absorption property is disposed outdoors.
According to the above method, the building for storing the separated fuel may be constructed for the separated fuel having the higher water absorption, so that the cost can be suppressed.

On the other hand, the biomass fuel co-firing system according to the present invention is, firstly, a biomass fuel co-firing system to be supplied to a boiler of a biomass power generation facility, the conveying means for conveying the biomass fuel to the boiler, and the biomass A plurality of fractionated fuels that are separated according to a physical quantity that influences a combustion state and arranged side by side in a conveyance direction of the conveyance unit; a supply unit that supplies each of the separated fuels to the conveyance mechanism; and the biomass Calculate the amount of steam generated by the boiler corresponding to the target power generation amount of the power generation facility, calculate the fuel input amount of the biomass fuel corresponding to the combustion energy in the boiler necessary for this, and the mixing ratio of each fractionated fuel Is calculated based on management information including information on the change in physical quantity of each fractionated fuel over time, and the supply unit is calculated based on the mixing ratio. And having a control means for controlling the feed rate of.
With the above-described configuration, a biomass fuel co-firing system capable of stably generating electric power even with various biomass fuels having different physical quantities related to combustion and changes with time thereof.

Second, the management information includes information on the storage amount of each separated fuel, information on the procurement plan time, and information on the cost, and the control means includes information on the storage amount and information on the procurement plan time. In addition, the fuel input amount of each separated fuel is adjusted based on the cost information.
By the above method, the power generation cost and the profit rate in the biomass power generation facility can be optimized.

Third, the control means supplies the fractionated fuel on the forward side with high combustion efficiency among the supply means when the power generation amount of the biomass power generation facility becomes lower than the target power generation amount. When the power generation amount of the biomass power generation facility is higher than the target power generation amount, among the supply means, the supply speed of the supply means for supplying the fractionated fuel with the lower combustion efficiency among the supply means It is characterized by performing control to increase the value.
With the above configuration, the power generation amount can be suppressed to a certain fluctuation range, so that the power generation amount can be stabilized even if the heat generation amount of each biomass fuel is uneven.

Fourth, an agitation mechanism for agitating the fractionated fuel is interposed in a conveyance path by the conveyance mechanism.
By the said structure, the combustion nonuniformity in a boiler can be suppressed and the output of a boiler can be stabilized.

Fifth, the physical quantity includes at least a particle size, a bulk density, a calorific value, and a moisture content of the fractionated fuel.
With the above configuration, the combustion efficiency of each fractionated fuel is stabilized, so that the combustion efficiency of the mixed biomass fuel can be easily adjusted.

Sixthly, among the fractionated fuels, the forward fractional fuel having a high water absorption property is disposed indoors, and the forward fractional fuel having a low water absorption property is disposed outdoors.
With the above-described configuration, the building for storing the separated fuel needs to be constructed only for the separated fuel on the front side having high water absorption, so that the construction cost can be suppressed.

Seventhly, the storage area for the separated fuel stored outdoors is provided with a floor structure capable of removing water from rain or snow from the storage area.
With the above configuration, separation and drying of the separated fuel and water stored outdoors can be promoted, and a decrease in combustion efficiency of the separated fuel can be suppressed.

  According to the mixed combustion method and mixed combustion system for biomass fuel according to the present invention, it is possible to stably generate electric power even for various biomass fuels having different physical quantities related to combustion and changes with time. In particular, when management information includes information on the storage amount of each separated fuel, information on the procurement schedule, and information on the cost, it is possible to adjust the fuel input amount of each separated fuel based on these information. Become. Thereby, the power generation cost and the profit rate in the biomass power generation facility can be optimized. Moreover, since the power generation amount can be suppressed to a certain fluctuation range, the power generation amount can be stabilized even if the heat generation amount of the biomass fuel is uneven.

It is a figure which shows the control flow (initial combustion basic flow) of the co-firing system of biomass fuel of this embodiment. It is a figure which shows the control flow (control flow at the time of continuous combustion) of the co-firing system of the biomass fuel of this embodiment. It is a schematic diagram (the 1) of the co-firing system of the biomass fuel of this embodiment. It is a schematic diagram (the 2) of the co-firing system of the biomass fuel of this embodiment. It is a schematic diagram (the 3) of the co-firing system of the biomass fuel of this embodiment. It is a schematic diagram (the 1) of the floor structure which comprises the mixed combustion system of the biomass fuel of this embodiment. It is a schematic diagram (the 2) of the floor structure which comprises the mixed combustion system of the biomass fuel of this embodiment. It is a figure which shows the example of the fuel management database (characteristic information) of the co-firing system of biomass fuel of this embodiment. It is a figure which shows the example of the fuel management database (management information) of the co-firing system of biomass fuel of this embodiment. It is a figure which shows the example of the fuel injection plan of the biomass fuel co-firing system of this embodiment.

  Hereinafter, the present invention will be described in detail with reference to embodiments shown in the drawings. However, the components, types, combinations, shapes, relative arrangements, and the like described in this embodiment are merely illustrative examples and not intended to limit the scope of the present invention only unless otherwise specified. .

  The schematic diagram of the co-firing system of the biomass fuel of this embodiment is shown in FIGS. The schematic diagram of the floor structure which comprises the co-firing system of the biomass fuel of this embodiment in FIG. 6, FIG. 3 to 7 are perspective views of an orthogonal coordinate system (X axis, Y axis, Z axis).

  The co-firing system 10 according to the present embodiment constitutes a biomass power generation facility, and has three areas of an outdoor storage yard 12, an indoor storage yard 34, and a combustion power generation area 52. The outdoor storage yard 12, the indoor storage yard 34, and the combustion power generation area 52 are connected by a conveying means (belt conveyor 60, steeply inclined belt conveyor 56) or the like.

  Although the details will be described later, the co-firing method performed by the co-firing system 10 of the present embodiment (see FIG. 1) is a method of co-firing biomass fuel supplied to the boiler 58 of the biomass power generation facility, and the target power generation amount of the biomass power generation facility The amount (Qv) of steam generated by the boiler 58 corresponding to (V0) is calculated, and the fuel input amount (Qf) of the biomass fuel corresponding to the combustion energy (Eb) in the boiler 58 required for this is calculated. To do.

  The biomass fuel is formed by a plurality of fractionated fuels (fuels 18A to 18D and fuels 42A to 42D described later) having different physical quantities (see FIG. 8) that affect the combustion state, and the mixing ratio of each fractionated fuel is It is calculated based on management information (see FIG. 9) including information on the change over time of the physical quantity of each fractionated fuel, and is formed by mixing the fractionated fuel based on the mixture ratio (Qf = Qfa + Qfb + Qfc + Qfd). It is a feature.

  In the mixed combustion system 10 of the present embodiment, those having different combustion conditions (physical quantities) in the outdoor storage yard 12 and the indoor storage yard 34, or biomass fuels separated and stored for each type of biomass fuel (separated fuel, hereinafter simply referred to as fuel) Are conveyed to the boiler 58 while being mixed in the middle of the conveyance in the conveyance means at a constant rate.

  As shown in FIG. 3, the outdoor storage yard 12 arranges the fuel used in the mixed combustion system 10 of the present embodiment with a low water absorption rate, that is, a fuel with a small change in combustion efficiency even when it receives rainfall or snowfall. Yard. Examples of the fuel having a low water absorption include those having a high oil content, wood covered with bark, and building waste materials. The outdoor storage yard 12 is an area surrounded by a fence 14, and a belt conveyor 60 is disposed in the center thereof. A storage area 16A and a storage area 16B are provided along one side surface of the belt conveyor 60, and a storage area 16C and a storage area 16D are provided along the other side surface.

  The storage area 16A stores a fuel 18A such as a coconut shell having a small particle size, and the storage area 16B stores a fuel 18B such as a coconut shell. A screw conveyor 20 is arranged between the storage area 16A and the storage area 16B. The screw conveyor 20 is formed in a groove 20a formed on the ground, and the opening of the groove 20a is covered with an iron lattice 20b. Fuel 18A and fuel 18B are supplied from a fuel input port 20c of the screw conveyor 20 by a wheel loader 24 (excavator) or the like. A chute 22 for supplying fuel to the belt conveyor 60 is provided at the end of the conveying direction of the screw conveyor 20, and the fuel 18 </ b> A and the fuel 18 </ b> B conveyed by the screw conveyor 20 are supplied to the belt conveyor 60 through the chute 22. .

  In the storage area 16C, long fuel 18C, such as building waste, is stored, and in the storage area 16D, short fuel 18D, such as building waste, is stored. Between the storage area 16C and the storage area 16D, the belt conveyor 26 provided with the crusher 26a is arrange | positioned. Fuel 18C and fuel 18D are fed into the crusher 26a by the wheel loader 24 and the like, and the fuel crushed by the crusher 26a is supplied to the belt conveyor 60 through the chute 22. Further, a weight sensor 26b is attached to the belt conveyor 26. When the weight of the fuel after crushing on the belt conveyor 26 exceeds a certain value, a warning or the like is generated and the operator stops the fuel injection so that the belt is stopped. The burden on the conveyor 26 can be reduced. Further, the speed of the belt conveyor 26 can be adjusted according to the weight, and the amount of fuel input for making the combustion energy variable can be adjusted. Each fuel is carried from the outside by a truck 28 or the like. In addition, floor structures 30 and 32 (FIGS. 6 and 7) are arranged in each storage area as described later.

  As shown in FIG. 6, floor structures 30 are provided in the storage areas 16A and 16B of the outdoor storage yard 12, and fuel is disposed thereon. FIG. 6 shows a floor structure 30 suitable for arranging fuels with small particle sizes (fuels 18A and 18B). The floor structure 30 has two inclined surfaces 30b having a pair of parallel drainage channels 30a as side surfaces and forming a mountain-shaped ridge line along the longitudinal direction of the drainage channel 30a at a position between the two drainage channels 30a. However, the inclined surface 30b has a shape in which the inclined surface (inclination angle θ2) in a form in which mountain folds and valley folds are repeated along the longitudinal direction of the drainage channel 30a is continuous. When fuel is arranged on the floor structure 30, even if there is rain or snow, the moisture is guided to the drainage channel 30 a through the valley fold (see the arrow in FIG. 6). Therefore, it is possible to reduce the remaining amount of moisture in the fuel and to reduce the increase in the moisture content of the fuel.

  FIG. 7 shows a floor structure 32 suitable for placing a fuel having a large particle size (fuel 18C, 18D) in the storage areas 16C, 16D. The floor structure 32 shown in FIG. 7 is formed by forming a mesh-type drainage floor 32c inside a rectangular frame 32a. Fuel is disposed on the drainage floor 32c, and water passes through the drainage floor 32c. It reaches the floor surface 32e of the floor structure 32 and flows from the discharge hole 32b at the lower part of the frame 32a to the drainage channel 32d. It is assumed that the fuel has a size larger than the drain hole of the drain floor 32c. In addition, the floor surface 32e of the floor structure 32 may be an inclined surface that becomes lower from the central portion toward the peripheral edge so that water can easily reach the drainage channel 32d. In any configuration, it is possible to reduce the increase in the moisture content accompanying the rain or snow from the fuel and suppress the decrease in the combustion efficiency.

  As shown in FIG. 4, the indoor storage yard 34 is covered with a building 36 through which the belt conveyor 60 passes. In the building 36, an inclined pit 38A and an inclined pit 38B are provided along one side surface of the belt conveyor 60, and a rectangular pit 40C and a rectangular pit 40D are provided along the other side surface. The inclined pits 38 </ b> A and the inclined pits 38 </ b> B have slopes that become lower as the floor surface moves away from the belt conveyor 60. Of the fuel stored in the indoor storage yard 34, the inclined pit 38A stores a fuel 42A such as a wood chip that has a higher total calorific value, and the inclined pit 38B stores the fuel 42A in the indoor storage yard 34Y. Among the fuels, the fuel 42B such as forward soot having a high combustion speed is stored.

  A screw conveyor 44A is disposed in the inclined pit 38A, and a screw conveyor 44B is disposed in the inclined pit 38B. The screw conveyor 44 </ b> A conveys the fuel 42 </ b> A stored in the inclined pit 38 </ b> A to the belt conveyor 60 side by screw rotation and supplies it to the belt conveyor 60 through the chute 22. Similarly, the screw conveyor 44B conveys the fuel 42B stored in the inclined pit 38B to the belt conveyor 60 side by screw rotation and supplies the fuel 42B to the belt conveyor 60 via the chute 22. The screw conveyors 44A and 44B can adjust the fuel supply speed by adjusting the rotation speed.

  The rectangular pits 40C and 40D store fuel 42C and fuel 42D such as thinned wood. A belt conveyor 46 having a crusher 46a is disposed between the rectangular pit 40C and the rectangular pit 40D. The crusher 46 a crushes the fuel 42 </ b> C and the fuel 42 </ b> D and supplies the crushed fuel to the belt conveyor 46. The belt conveyor 46 conveys the crushed fuel and supplies it to the belt conveyor 60 via the chute 22.

  A truck 28 for carrying fuel can enter and leave the building 36, and an area is provided for the truck 28 to carry fuel 42A and 42B to the inclined pits 38A and 38B. A standby area 50 is also provided for the overhead crane 48 to be described later to carry the fuels 42C and 42D from the truck 28.

  In the building 36, the standby area 50, the rectangular pit 40C, the belt conveyor 46, and the rectangular pit 40D are arranged in a line in that order in the Y-axis direction (horizontal direction). A crane 48 is arranged. The overhead crane 48 is a pair of rails 48a disposed in the upper portion of the building 36 along the Y-axis direction, a main body 48b disposed so as to straddle the rails 48a, and traveling along the longitudinal direction of the rails 48a, and a main body 48b. A moving part 48c that moves in the X-axis direction (horizontal direction) and a gripping mechanism 48d that is attached to the moving part 48c and is movable in the Z-axis direction (vertical direction) and grips the fuels 42C and 42D. Have.

  The overhead crane 48 operates the main body 48b, the moving part 48c, and the gripping mechanism 48d to take out the fuel 42C (fuel 42D) from the truck 28 (not shown) waiting in the standby area 50, and to form the rectangular pit 40C ( The fuel 42C (fuel 42D) can be conveyed and supplied to the rectangular pit 40D). Moreover, the overhead crane 48 can take out the fuel 42C (fuel 42D) from the rectangular pit 40C (rectangular pit 40D), and can convey and throw it into the crusher 46a. The belt conveyor 46 is provided with a weight sensor 46b as described above, and the overhead crane 48 supplies the fuel 42C and 42D to the crusher 46a when the weight of the fuel after crushing on the belt conveyor 46 exceeds a certain value. The operation | movement to throw in can be stopped temporarily and the burden to the belt conveyor 46 can be reduced. Further, the speed of the belt conveyor 46 can be adjusted according to the weight, and the amount of fuel input for making the combustion energy variable can be adjusted.

  Similarly, the belt conveyor 60 is provided with a weight sensor 60a. When the weight of fuel on the belt conveyor 60 exceeds a certain value, the screw conveyor 20, the belt conveyor 26, the screw conveyor 44A, the screw conveyor 44B, the belt conveyor. 46, the operation of the overhead crane 48 can be temporarily stopped (the operator can be alerted with a warning sound) to reduce the load on the belt conveyor 60.

  As shown in FIG. 5, the combustion power generation area 52 includes a hopper 54, a steeply inclined belt conveyor 56, a boiler 58, and the like. The hopper 54 is a container that receives fuel (fuels 18A to 18D and fuels 42A to 42D) supplied from the belt conveyor 60, and a screw type agitator 54a is attached to the lower part (opening) thereof. Therefore, the fuel introduced into the hopper 54 is agitated by the agitator 54a, or the fuel that has not been sufficiently crushed by the crushers 26a and 46a is crushed to become a mixed fuel with less unevenness, resulting in a steeply inclined belt conveyor 56. To be supplied.

  The steeply inclined belt conveyor 56 conveys the mixed fuel to the boiler 58. The steeply inclined belt conveyor 56 has a substantially horizontal conveying path at a position directly below the hopper 54, but the conveying path inclines upward from the middle thereof, and the mixed fuel is supplied to the receiving hopper 58 a attached to the boiler 58. Can be supplied. The inclined portion of the steeply inclined belt conveyor 56 is supported by a support column 56a and covered with a hood 56b. The conveyor belt 56c of the steeply inclined belt conveyor 56 is provided with crosspieces 56d at regular intervals in the circumferential direction, and fins 56e are provided on the side surfaces of the conveyor belt 56c. Therefore, the mixed fuel is supported by the crosspiece 56d from below in the inclined region of the conveyance path and is supported by the fin 56e from the side surface direction to prevent the mixed fuel from leaking from the conveyance belt 56c. Further, in the inclined portion, even if the mixed fuel leaks from the conveyance belt 56c, the mixed fuel is prevented from being scattered around by the hood 56b.

  The boiler 58 is, for example, a stoker-type or fluidized-bed type boiler, and heats a steam pipe 58c that burns mixed fuel and circulates in the boiler 58 to generate steam in the steam pipe 58c, thereby generating a turbine (not shown). To supply high-heat and high-pressure steam. The above-described receiving hopper 58a is attached to the boiler 58, and a fixed amount of mixed fuel is introduced into the boiler 58 by rotating a rotary valve 58b disposed below (opening) the receiving hopper 58a.

  The control means (not shown) is, for example, an application installed in a PC (personal computer), and via a PC interface, the belt conveyor 60 (weight sensor 60a), the screw conveyor 20, and the belt conveyor 26 (weight sensor 26b). , Screw conveyor 44A, screw conveyor 44B, belt conveyor 46 (weight scale 46b), and overhead crane 48. Furthermore, the control means is connected to a thermometer, a pressure gauge, a flow meter, and a wattmeter of a turbine (not shown) via the interface.

  In addition, the PC includes characteristic information that covers the physical quantity (including physical properties related to combustion) of fuel combustion in the state when each fuel is carried in, the total calorific value and the combustion speed calculated from the physical quantity (see FIG. 8). Is stored as a database. In addition, in the database, the storage position of each fuel, the storage history of each fuel, changes over time in physical quantities and calorific values based on the storage history, procurement time information, storage in a form associated with the aforementioned characteristic information Management information (see FIG. 9) covering the quantity, price, etc. is stored.

  FIG. 1 shows a control flow (initial combustion basic flow) of the biomass fuel co-firing system of the present embodiment, and FIG. 2 shows a control flow (control flow during continuous combustion) of the biomass fuel co-firing system of the present embodiment. . The mixed combustion system 10 according to the present embodiment operates under the control of the above-described control means, but in order to stably output an initial combustion basic flow for determining an initial combustion state and a power generation amount within a certain range during continuous operation. It operates according to the control flow during continuous combustion.

  First, in the initial combustion basic flow shown in FIG. 1, when the target power generation amount P0 [kW] in the turbine (not shown) is set, the control means requires the steam amount Qv required by the turbine in consideration of the conversion efficiency of the turbine. [T / h] (the output of the turbine) is calculated based on the temperature (for example, 500 [° C.]), the pressure (for example, 5 [MPa]), and the flow rate of the steam. Then, the control means calculates the combustion energy Eb [kcal / min] of the mixed fuel for generating the calculated amount of steam based on the conversion efficiency of the boiler 58, and calculates the calculated combustion energy and the above-described characteristic information and management. Using the information, the input amount Qf [t / h] of the mixed fuel and its breakdown (mixing ratio) are calculated. The breakdown is as follows: base fuel a (Qfa [t / h]), high heat generation fuel b (Qfb [t / h]), low heat generation fuel c (Qfc [t / h]), high combustion rate fuel d (Qfd [ t / h]) and Qf = Qfa + Qfb + Qfc + Qfd. Further, the combustion energy Eb of the mixed fuel is the sum of the total calorific values of each fuel.

  As a result, the control means feeds the conveying speed of the conveying means (the belt conveyor 60 and the steeply inclined belt conveyor 56) and the feeding speed of the supplying means (the screw conveyor 20, the belt conveyor 26, the screw conveyor 44A, the screw conveyor 44B, and the belt conveyor 46). Then, the conveying frequency of the overhead crane 48 is set, and the mixed fuel with the total input amount being Qf is supplied to the boiler 58. As a result, substantially the same power as P0 is output from the turbine (not shown).

  Next, in the control flow at the time of continuous combustion shown in FIG. 2, the control means calculates a difference ΔP0 [kW] between the current power generation amount of the turbine (not shown) and the target power generation amount, and based on this difference, the current steam The difference ΔQv [t / h] between the amount and the target steam amount and the time change ratio dΔQv [t / (h · min)] are calculated. Further, a difference ΔEb [kcal / min] between the current combustion energy and the target combustion energy is calculated from ΔQv.

  If ΔEb is negative (the amount of power generation is reduced), the mixing ratio of the mixed fuel is changed. That is, the input amount of the base fuel a is constant, the input amounts of the high heat generation fuel b and the high combustion speed fuel d are increased by a constant amount, and conversely the input amount of the low heat generation fuel c is decreased by a constant amount. Then, the current power generation amount is measured again, and if the difference between the value and the target power generation amount and the aforementioned dΔQv is less than or equal to the allowable value, the combustion is continued as it is. Repeat the flow so that it is below the tolerance.

  Conversely, when ΔEb is positive (the amount of power generation is increased), the amount of base fuel a input is constant, the amounts of high heat generation fuel b and high combustion speed fuel d are decreased by a constant amount, and conversely low heat generation. The input amount of the fuel c is increased by a certain amount. Then, the current power generation amount is measured again, and if the difference between the value and the target power generation amount and the aforementioned dΔQv is less than or equal to the allowable value, the combustion is continued as it is. Repeat the flow so that it is below the tolerance. In any case, the control means adjusts the input amount by adjusting the conveyance speed of the conveyance means, the supply speed of the supply means, and the supply frequency of the overhead crane 48.

  FIG. 8 shows an example of a fuel management database (characteristic information) of the biomass fuel co-firing system of the present embodiment, and FIG. 9 shows an example of a fuel management database (management information) of the biomass fuel co-firing system of the present embodiment.

  As shown in FIG. 8, in the present embodiment, for example, thinned wood, construction waste, wood chips, coconut shells, straw (rice husk), and coconut shells are registered as fuel numbers. The average particle size, bulk density, moisture content, total calorific value calculated from these physical quantities (calorific value taking into account combustion characteristics such as moisture content and furnace type) and combustion calorific rate are covered as fuel characteristic information. Yes. Among these, building waste, wood chips, and coconut shells can be used as the base fuel a (Qfa) because the total calorific value is in the middle. Further, since the coconut shell has the highest total calorific value, it can be used as the highly exothermic fuel b (Qfb). On the other hand, thinned wood can be used as low heat generation fuel c (Qfc) because it has the lowest total calorific value, and soot can be used as high combustion speed fuel d (Qfd) because it has the fastest heat generation rate.

  Building waste, coconut shells, and coconut shells are stored in the outdoor storage yard 12 because of their low water absorption. Among these, since the average particle diameter becomes large, the building waste material is stored as fuel 18C (long) in the storage area 16C shown in FIG. 3 or as fuel 18D in the storage area 16D. In addition, since the average particle diameter of the coconut shell and the coconut shell is small, for example, the coconut shell is stored as the fuel 18A in the storage area 16A, and the coconut shell is stored as the fuel 18B in the storage area 16B.

  Thinned wood, wood chips and firewood are stored in the indoor storage yard 34 because of their high water absorption rate. Among these, since the average particle diameter becomes large, the thinned wood is stored as the fuel 42C in the rectangular pit 40C shown in FIG. 4 or as the fuel 42D in the rectangular pit 40D. Further, since the average particle diameter of the wood chips and the soot is small, for example, the wood chips are stored as the fuel 42A in the inclined pit 38A, and the insulator shell is stored as the fuel 42B in the inclined pit 38B.

  As shown in FIG. 9, the moisture content and total heat generation of each fuel are adjusted based on the storage state of each fuel, and the mixing ratio of each fuel is adjusted according to the storage amount, procurement schedule, and price of each fuel. Do. This operation is performed by the control means.

  For each fuel, the estimated value accompanying the change in moisture content with time is calculated based on the number of storage days, average temperature, average humidity, accumulated solar radiation, and accumulated precipitation (snowfall), and based on this, the total heat generation changes with time. Calculate the estimated value associated with. For example, when the average temperature is high or the average humidity is low, the moisture content decreases in proportion to the number of storage days. Conversely, when the average temperature is low or the average humidity is high, the moisture content is proportional to the storage days. Will increase. In addition, the moisture content decreases as the proportion of accumulated solar radiation based on accumulated precipitation increases, and conversely increases as it decreases. In addition, if the weather continues after the day of precipitation, the water content will decrease.

For example, since thinned wood, wood chips, and firewood are stored in the indoor storage yard 34, calculation is possible without considering the integrated solar radiation amount and the integrated precipitation amount. FIG. 9 shows that the moisture content of these fuels has decreased, thereby increasing the total heat generation.
Moreover, since building waste materials, coconut shells, and coconut shells are stored in the outdoor storage yard 12, it is necessary to calculate in consideration of integrated solar radiation and integrated precipitation. FIG. 9 shows that the moisture content of these fuels has increased, thereby reducing the overall heat generation.

  Based on the estimated value calculated in this way, the control means can calculate the fuel input amount Qf and its breakdown (mixing ratio). It should be noted that in the building waste, coconut shell and coconut shell, the accumulated solar radiation and accumulated precipitation are different because each particle diameter is different, and the larger the fuel particle diameter is, the larger the fuel volume (weight) becomes the standard This is because the ratio of the surface area of the fuel becomes small.

  In this embodiment, building waste, wood chips, and coconut shells are used as the base fuel a. Of these, the amount of wood chips stored is less than that of other base fuels, and the procurement schedule is the longest. Slow and expensive. Therefore, the control means can determine that the mixing ratio of the wood chips in the base fuel a is less than that of the other base fuel a or is not used.

  FIG. 10 is a diagram showing an example of a fuel input plan of the biomass fuel co-firing system of the present embodiment. As shown in FIG. 10, the power generation output (5000 [kW]) on the day is set, and the fuel cost and the profit rate corresponding to this are calculated. At that time, based on the determination by the control means described above, the set input amount and the steam amount of each fuel corresponding to the power generation amount are calculated. As shown in FIG. 10, the power generation amount is set to a size that can be covered without supplying all the fuel, so the control means determines that it is not necessary to use coconut shells and coconut shells. In addition, wood chips are not used because they are expensive and have little storage. Thus, since the fuel cost can be calculated if the set input amount for each fuel is known, the profit rate can be calculated from the sales price and the fuel cost related to the power generation output. Further, when there is a change in the power generation amount as described above, the mixing ratio may be adjusted according to the flow of FIG.

  In the present embodiment, the biomass fuel has been described with some examples. However, there are many actual fuels, some of which have high combustion efficiency (high calorific value, high combustion rate) and low. Therefore, classify these in order of combustion efficiency, use the one with the higher combustion efficiency (there is more than one) as the high heat generation fuel or the fuel with the higher combustion rate, and the one with the lower combustion efficiency (there are more than one) What is necessary is just to use as a low exothermic fuel. Moreover, what belongs to the order with medium combustion efficiency (it exists in multiple numbers) should just be used as a base fuel.

  In a power generation system for various biomass fuels, it can be used as a biomass fuel co-firing method for stabilizing and improving combustion efficiency and a biomass fuel co-firing system.

10 ......... Mixed fire system, 12 ......... Outdoor storage yard, 14 ......... Fence, 16A, 16B, 16C, 16D ......... Storage area, 18A, 18B, 18C, 18D ......... Fuel, 20 ......... Screw conveyor, 20a ......... groove, 20b ......... iron grid, 20c ......... fuel inlet, 22 ......... chute, 24 ......... wheel loader, 26 ......... belt conveyor, 26a ......... crusher, 26b ......... Weight sensor, 28 ......... Truck, 30 ......... Floor structure, 30a ......... Drainage channel, 30b ......... Inclined surface, 32 ......... Floor structure, 32a ......... Frame, 32b ......... Drain hole, 32c ......... Draining floor, 32d ......... Drainage channel, 32e ......... Floor surface, 34 ......... Indoor storage yard, 36 ......... Building, 38A, 38B ......... Inclined pit, 40C, 40D ......... rectangle 42A, 42B, 42C, 42D ... Fuel 44A, 44B ... Screw conveyor 46 ... Belt conveyor 46a ... Crusher 46b ... Weight sensor 48 ... Ceiling Crane, 48a ... Rail, 48b ... Main body, 48c ... Moving part, 48d ... Holding mechanism, 50 ... Standby area, 52 ... Combustion power generation area, 54 ... Hopper, 54a ......... Stirrer, 56 ......... Steeply inclined belt conveyor, 56a ......... Strut, 56b ......... Hood, 56c ......... Conveyor belt, 56d ......... Cross, 56e ...... Fin, 58 ......... Boiler, 58a ... receiving hopper, 58b ... rotary valve, 58c ... steam piping, 60 ... belt conveyor, 60a ... weight sensor.

Claims (14)

A method of co-firing biomass fuel supplied to a boiler of a biomass power generation facility,
Calculate the amount of steam generated by the boiler corresponding to the target power generation amount of the biomass power generation facility, calculate the fuel input amount of the biomass fuel corresponding to the combustion energy in the boiler necessary for this,
The biomass fuel is formed by a plurality of fractionated fuels having different physical quantities that affect the combustion state, and the mixing ratio of each fractionated fuel is calculated based on management information including information on the change in the physical quantity of each fractionated fuel over time. And forming the mixed fuel based on the mixing ratio to mix biomass fuel.   The management information includes information on a storage amount of each separated fuel, information on a procurement plan time, and information on a cost, and adjusts the fuel input amount of each separated fuel based on the information. The method for co-firing biomass fuel as described in 1. When the power generation amount of the biomass power generation facility is lower than the target power generation amount, in the biomass fuel, the mixing ratio of the fractionated fuel on the forward side with high combustion efficiency is increased,
The mixing ratio of the fractionated fuel on the forward side having low combustion efficiency is increased in the biomass fuel when the power generation amount of the biomass power generation facility becomes higher than the target power generation amount. A method for co-firing biomass fuel as described in 1.   The biomass fuel co-firing method according to any one of claims 1 to 3, wherein the fractionated fuel is agitated and mixed before being supplied to the boiler.   5. The biomass fuel co-firing method according to claim 1, wherein the fractionated fuel is stored separately for each of the different physical quantities or for each kind of the fractionated fuel.   6. The biomass fuel co-firing method according to claim 1, wherein the physical quantity includes at least a particle size, a bulk density, a calorific value, and a moisture content of the fractionated fuel.   7. The biomass fuel according to claim 5, wherein, among the fractionated fuels, a front-side fractionated fuel having a high water absorption is disposed indoors, and a front-side fractionated fuel having a low water absorption is disposed outdoors. Mixed firing method. A biomass fuel co-firing system for supplying to a boiler of a biomass power generation facility,
Conveying means for conveying the biomass fuel to the boiler;
The biomass fuel is separated according to a physical quantity that affects the combustion state, and a plurality of separated fuels arranged side by side along the transport direction of the transport means;
Supply means for supplying each separated fuel to the transport mechanism;
Calculate the amount of steam generated by the boiler corresponding to the target power generation amount of the biomass power generation facility, calculate the fuel input amount of the biomass fuel corresponding to the combustion energy in the boiler necessary for this, Control means for calculating a mixing ratio based on management information including information on temporal change of the physical quantity of each fractionated fuel, and controlling a supply speed of the supplying means based on the mixing ratio; A biomass fuel co-firing system. The management information includes information on the storage amount of each separated fuel, information on the procurement plan time, and information on the cost,
9. The mixed combustion of biomass fuel according to claim 8, wherein the control means adjusts the fuel input amount of each fractionated fuel from the information on the storage amount, the information on the procurement schedule, and the information on the cost. system. The control means includes
When the power generation amount of the biomass power generation facility is lower than the target power generation amount, among the supply means, increase the supply speed of the supply means for supplying the fractionated fuel on the forward side with high combustion efficiency,
When the power generation amount of the biomass power generation facility becomes higher than the target power generation amount, control is performed to increase the supply speed of the supply unit that supplies the fractionated fuel on the forward side with low combustion efficiency among the supply units. The biomass fuel co-firing system according to claim 8 or 9.   11. The biomass fuel co-firing system according to claim 8, wherein an agitation mechanism for agitating the fractionated fuel is interposed in a conveyance path by the conveyance mechanism.   The biomass fuel co-firing system according to any one of claims 8 to 11, wherein the physical quantity includes at least a particle size, a bulk density, a calorific value, and a moisture content of the fractionated fuel.   13. The fractionated fuel having a higher water absorption capacity is stored indoors, and the front fuel having a lower water absorption capacity is stored outdoors. A biomass fuel mixed combustion system according to claim 1.   14. The biomass fuel according to claim 13, wherein a floor structure capable of removing water from rain or snow from the storage area is provided in the storage area of the separated fuel stored outdoors. Mixed firing system.

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