JP7519263B2 - Biomass Combustion Equipment - Google Patents

Description

The present invention relates to a biomass combustion facility and a biomass combustion method that combusts biomass fuel transported by a fuel transport device in a combustion chamber of a combustion furnace.

Biomass fuels are attracting attention as a renewable energy resource. By using biomass fuels as fuel for power generation in biomass combustion facilities, it is possible to reduce carbon dioxide emissions compared to using fossil fuels.

In biomass combustion facilities, if the biomass fuel being burned has a high moisture content, the combustion becomes unstable. Therefore, a biomass incineration system has been proposed in which the biomass fuel is dried in a drying chamber and the dried biomass fuel is burned in a combustion chamber separated from the drying chamber by a partition wall (see, for example, Patent Document 1).

In the biomass incineration system described in Patent Document 1, the steam flow rate of the dried exhaust gas discharged from the drying chamber to the outside is measured, and based on this measurement, it is determined whether the moisture content of the biomass fuel in the drying chamber is greater than or equal to the upper limit of the standard range for moisture content, and the temperatures of the drying chamber and combustion chamber in the biomass combustion furnace are adjusted based on the result of this determination.

JP 2017-187199 A

In the biomass incineration system described in Patent Document 1, the temperature of the drying chamber and the combustion chamber is adjusted based on the measured value of the steam flow rate of the dried exhaust gas resulting from drying the biomass fuel in the drying chamber after it is supplied to the biomass combustion furnace. Therefore, the temperature of the drying chamber and the combustion chamber cannot be accurately adjusted to a temperature that corresponds to the actual moisture content of the biomass fuel before it is supplied to the biomass combustion furnace, and there is a risk that the combustion operation cannot be stabilized. In addition, the temperature adjustment performed in the biomass incineration system described in Patent Document 1 is a reactive type of temperature adjustment, and when the properties (moisture content) of the biomass fuel supplied to the biomass combustion furnace suddenly change, the temperature adjustment amount cannot be changed immediately without delay, and there is a risk that the combustion operation cannot be stabilized.

The present invention was made in consideration of the above problems, and aims to provide a biomass combustion facility and a biomass combustion method that can accurately measure the moisture content of biomass fuel before it is burned in a combustion furnace, thereby stabilizing combustion operation.

The characteristic configuration of the biomass combustion facility according to the present invention for solving the above problems is as follows:
A biomass combustion facility configured to combust biomass fuel transported by a fuel transport device in a combustion chamber of a combustion furnace,
The present invention is provided with a non-contact moisture meter that measures the moisture content of biomass fuel by irradiating the biomass fuel with electromagnetic waves.

According to the biomass combustion equipment of this configuration, the biomass fuel transported by the fuel transport device is irradiated with electromagnetic waves and the moisture content of the biomass fuel is measured by the non-contact moisture meter, so that the moisture content of the biomass fuel can be accurately measured before it is burned in the combustion furnace. Therefore, if the combustion of the biomass fuel in the combustion furnace is controlled based on the moisture content measured by the non-contact moisture meter, it is possible to stabilize the combustion operation.

In the biomass combustion facility according to the present invention,
The fuel conveying device includes:
A casing for containing biomass fuel;
an electromagnetic wave transmitting member attached to an opening provided in the casing;
Equipped with
It is preferable that the biomass fuel in the casing is irradiated with electromagnetic waves through the electromagnetic wave transparent member.

According to the biomass combustion equipment of this configuration, an opening is provided in the casing that contains the transported biomass fuel, and the biomass fuel inside the casing is configured to be irradiated with electromagnetic waves through an electromagnetic wave transparent member attached to this opening. With this configuration, the electromagnetic wave transparent member can prevent dust and other particles that fly up from the biomass fuel during transport from adhering to the electromagnetic wave transmitter and receiver of the non-contact moisture meter. Therefore, it is possible to prevent problems with the transmission and reception of electromagnetic waves in advance, and it is possible to stably obtain accurate measurement values over a long period of time.

In the biomass combustion facility according to the present invention,
It is preferable to provide a condensation prevention means for preventing condensation from occurring on the surface of the electromagnetic wave transmitting member on the side facing the biomass fuel inside the casing.

With the biomass combustion equipment of this configuration, the condensation prevention means can prevent condensation from occurring on the surface of the electromagnetic wave transparent member facing the biomass fuel inside the casing, making it possible to prevent measurement errors caused by the effects of water droplets.

In the biomass combustion facility according to the present invention,
It is preferable to provide a water droplet removing means for removing water droplets adhering to the surface of the electromagnetic wave transmitting member on the side facing the biomass fuel inside the casing.

With the biomass combustion equipment of this configuration, even if water droplets resulting from the moisture contained in the biomass fuel adhere to the surface of the electromagnetic wave transparent member facing the biomass fuel inside the casing, the water droplets can be removed by the water droplet adhesion prevention means. Therefore, it is possible to prevent measurement errors caused by the influence of water droplets.

In the biomass combustion facility according to the present invention,
The electromagnetic wave transmitting member preferably has water repellency.

In the biomass combustion equipment of this configuration, the electromagnetic wave transparent member has water repellency. As a result, even if condensation occurs on the surface of the electromagnetic wave transparent member facing the biomass fuel inside the casing, the water droplets are immediately repelled and prevented from adhering to the surface of the electromagnetic wave transparent member. Therefore, measurement errors caused by the influence of water droplets can be suppressed.

In the biomass combustion facility according to the present invention,
The combustion furnace has at least one of a fuel input device that inputs the biomass fuel transported from the fuel transport device into the combustion chamber, a fire grate that transports the biomass fuel within the combustion chamber, a combustion air damper that adjusts the amount of combustion air supplied to the combustion chamber, and a recirculated exhaust gas damper that adjusts the amount of recirculated exhaust gas supplied to the combustion chamber,
It is preferable to further provide a combustion state control means for adjusting at least one of the following, depending on the moisture percentage measured by the non-contact moisture meter: the speed at which the biomass fuel is transported by the fuel transport device, the position at which the biomass fuel is injected by the fuel injector, the speed at which the biomass fuel is fed by the grate, the amount of combustion air supplied by the combustion air damper, and the amount of recirculated exhaust gas supplied by the recirculated exhaust gas damper.

According to the biomass combustion equipment of this configuration, the combustion furnace has at least one of a fuel input device that inputs the biomass fuel transported from the fuel transport device into the combustion chamber, a grate that sends the biomass fuel in the combustion chamber, a combustion air damper that adjusts the amount of combustion air supplied to the combustion chamber, and a recirculated exhaust gas damper that adjusts the amount of recirculated exhaust gas supplied to the combustion chamber. The biomass fuel transported from the fuel transport device to the combustion furnace is input into the combustion chamber by the fuel input device, and is sent by the grate while receiving a supply of combustion air in the combustion chamber and combusted, and recirculated exhaust gas is supplied into the combustion chamber as needed. Then, the combustion state control means adjusts at least one of the transport speed of the biomass fuel by the fuel transport device, the input position of the biomass fuel by the fuel input device, the feed speed of the biomass fuel by the grate, the amount of combustion air supplied by the combustion air damper, and the amount of recirculated exhaust gas supplied by the recirculated exhaust gas damper according to the moisture percentage measured by the non-contact moisture meter. This ensures stable combustion operation.

In the biomass combustion facility according to the present invention,
The non-contact moisture meter is preferably a transmission type non-contact moisture meter that measures the moisture content of the biomass fuel by electromagnetic waves transmitted through the biomass fuel.

The biomass combustion equipment of this configuration employs a non-contact moisture meter that measures the moisture content of biomass fuel using electromagnetic waves that pass through the biomass fuel, making it possible to accurately measure the moisture content of the biomass fuel even if an air layer exists between the biomass fuel and the fuel.

In the biomass combustion facility according to the present invention,
The non-contact moisture meter is preferably a reflection type non-contact moisture meter that measures the moisture content of the biomass fuel by electromagnetic waves that are transmitted through the biomass fuel and reflected.

The biomass combustion equipment of this configuration employs a reflective non-contact moisture meter that measures the moisture content of biomass fuel using electromagnetic waves that are transmitted through the biomass fuel and reflected, eliminating the need to provide a separate receiving unit just for receiving the electromagnetic waves, further simplifying the structure.

Next, the characteristic configuration of the biomass combustion method according to the present invention for solving the above problems is as follows:
A biomass combustion method in which biomass fuel transported by a fuel transport device is combusted in a combustion chamber of a combustion furnace, comprising:
The present invention includes a moisture content measuring step of measuring the moisture content of a biomass fuel by irradiating the biomass fuel with electromagnetic waves.

The biomass combustion method of this configuration includes a moisture content measurement step in which the moisture content of the biomass fuel transported by the fuel transport device is measured by irradiating the biomass fuel with electromagnetic waves. This makes it possible to accurately measure the moisture content of the biomass fuel before it is combusted in the combustion furnace. Therefore, by controlling the combustion of the biomass fuel in the combustion furnace based on the measured moisture content value obtained in the moisture content measurement step, it becomes possible to stabilize the combustion operation.

In the biomass combustion method according to the present invention,
The combustion furnace has at least one of a fuel input device that inputs the biomass fuel transported from the fuel transport device into the combustion chamber, a fire grate that transports the biomass fuel within the combustion chamber, a combustion air damper that adjusts the amount of combustion air supplied to the combustion chamber, and a recirculated exhaust gas damper that adjusts the amount of recirculated exhaust gas supplied to the combustion chamber,
It is preferable that the method further includes a combustion state control step of adjusting at least one of the following, depending on the moisture percentage measured in the moisture percentage measurement step: the biomass fuel transport speed by the fuel transport device, the biomass fuel input position by the fuel input device, the biomass fuel feed speed by the grate, the amount of combustion air supplied by the combustion air damper, and the amount of recirculated exhaust gas supplied by the recirculated exhaust gas damper.

The biomass combustion method of this configuration further includes a combustion state control step of adjusting at least one of the following depending on the moisture percentage measured in the moisture percentage measurement step: the transport speed of the biomass fuel by the fuel transport device, the position at which the biomass fuel is introduced by the fuel injector, the feed speed of the biomass fuel by the grate, the amount of combustion air supplied by the combustion air damper, and the amount of recirculated exhaust gas supplied by the recirculated exhaust gas damper. This ensures stable combustion operation.

FIG. 1 is a schematic diagram showing a schematic configuration of a biomass combustion facility according to one embodiment of the present invention. FIG. 2 is a schematic diagram showing the structure of a fuel conveying device provided in a biomass combustion facility according to one embodiment of the present invention, in which (a) is a side view with a portion cut away, and (b) is a cross-sectional end view taken along line A-A in (a). FIG. 3 is a schematic diagram showing another structure of a fuel transport device provided in a biomass combustion facility according to an embodiment of the present invention. FIG. 4 is a diagram illustrating devices related to preventing condensation and removing water droplets that are provided in a fuel conveying device, where (a) is a heater, (b) is a wiper device, and (c) and (d) are air blowing devices. FIG. 5 is a block diagram showing a schematic configuration of a combustion control system in a biomass combustion facility according to one embodiment of the present invention. FIG. 6 is a graph showing the correlation between the amplitude/phase ratio of microwaves and the official moisture content (dry weight method). FIG. 7 is a functional block diagram of a combustion control system in a biomass combustion facility according to one embodiment of the present invention. FIG. 8 is a schematic diagram illustrating another embodiment of the biomass combustion facility of the present invention.

The present invention will now be described with reference to the drawings. However, the present invention is not intended to be limited to the embodiments described below or the configurations shown in the drawings.

<Overall configuration of biomass combustion equipment>
FIG. 1 is a schematic diagram showing a schematic configuration of a biomass combustion facility according to an embodiment of the present invention. As shown in FIG. 1, the biomass combustion facility 1 mainly includes a fuel supplying machine 2, a fuel conveying device 3, a combustion furnace 4, a boiler 5, and an economizer 6. Biomass fuel stored in a biomass fuel supply building (not shown) is conveyed to a combustion furnace 4 via a fuel supplying machine 2 consisting of a fuel metering feeder (not shown) and a fuel conveying device 3 equipped with a non-contact moisture meter 45 (48) described later, and is burned in the combustion furnace 4. Exhaust gas generated by combustion in the combustion furnace 4 is sent to the boiler 5 and the economizer 6 by the induction action of an induction fan (not shown) and heat is recovered. Thereafter, the exhaust gas is cooled in a cooling tower (not shown), dusted by a bag filter (not shown), and then released to the outside through a chimney (not shown).

<Fuel Delivery Device>
2A and 2B are schematic diagrams showing the structure of a fuel transport device provided in a biomass combustion facility according to an embodiment of the present invention, with (a) being a partially cutaway side view and (b) being a cross-sectional end view taken along line A-A in (a). As shown in Fig. 2A, a belt conveyor type is used as the fuel transport device 3. The fuel transport device 3 includes a casing 11, a belt conveyor 13 disposed within the casing 11, and a belt conveyor drive device 15 that drives the belt conveyor 13.

[casing]
The casing 11 has a rectangular cylindrical casing body 20 extending in the conveying direction, and an upwardly opening inlet 21 is provided at the upstream end of the casing body 20 in the conveying direction, and an downwardly opening outlet 22 is provided at the downstream end of the casing body 20 in the conveying direction.

[belt conveyor]
The belt conveyor 13 includes a driving wheel 25, a driven wheel 26, and an endless belt 27. The driving wheel 25 and the driven wheel 26 are disposed at a predetermined interval in the conveying direction inside the casing body 20. The endless belt 27 is wound around the driving wheel 25 and the driven wheel 26.

[Belt conveyor drive device]
The belt conveyor driving device 15 is configured to include a driving motor and a power transmission mechanism that transmits the rotational power of the driving motor to the driving wheels 25. In the belt conveyor 13, the belt conveyor driving device 15 drives the endless belt 27 to perform a circular motion, so that the biomass fuel, indicated by the symbol M in FIG. 2( a ) that has fallen onto the endless belt 27 through the inlet 21, can be transported to the discharge outlet 22.

<Electromagnetic wave transmitting material>
As shown in Fig. 2(b), the casing body 20 has a top plate 31 and a bottom plate 32 arranged opposite to each other in the vertical direction, and a left plate 33 and a right plate 34 arranged opposite to each other in the left-right direction. A pair of openings 40 are formed in the top plate 31 and the bottom plate 32 of the casing body 20 at positions facing each other across the biomass fuel indicated by symbol M in Fig. 2(b) on the endless belt 27. A plate-shaped electromagnetic wave transmitting member 41 is attached to each opening 40 so as to be flush with the inner surface of the casing body 20. The electromagnetic wave transmitting member 41 is made of a corrosion-resistant material that can transmit microwaves, which are electromagnetic waves with frequencies of about 300 MHz to 300 GHz (wavelength: about 1 m to 1 mm). The material constituting the electromagnetic wave transparent member 41 is not particularly limited as long as it is microwave-transmissive and corrosion-resistant, but a corrosion-resistant resin is preferable, such as polytetrafluoroethylene resin, liquid crystal polymer, polyether ether ketone resin, polyetherimide resin, polyamide imide resin, polyphenylene sulfide resin, etc., and of these, polytetrafluoroethylene resin known under the trade name Teflon (registered trademark) is particularly preferable.

<Non-contact moisture meter>
A transmission-type non-contact moisture meter 45 is attached to the casing body 20, which measures the moisture percentage of the biomass fuel by irradiating microwaves onto the biomass fuel transported by the belt conveyor 13 inside the casing body 20. By employing the transmission-type non-contact moisture meter 45, the moisture percentage of the biomass fuel can be accurately measured even if an air layer exists between the biomass fuel and the casing body 20.

The non-contact moisture meter 45 has a microwave transmitter 45a, a microwave receiver 45b, and a moisture percentage calculation unit 161 (see FIG. 7) described later. The microwave transmitter 45a is disposed on the back side of the electromagnetic wave-transmitting member 41 attached to the top plate 31 of the casing body 20. The microwave receiver 45b is disposed on the back side of the electromagnetic wave-transmitting member 41 attached to the bottom plate 32 of the casing body 20. The microwaves transmitted from the microwave transmitter 45a are irradiated to the biomass fuel indicated by the symbol M in FIG. 2(b) on the endless belt 27 through the electromagnetic wave-transmitting member 41 attached to the top plate 31 of the casing body 20. The irradiated microwaves penetrate the biomass fuel on the endless belt 27, penetrate the endless belt 27, and are received by the microwave receiver 45b through the electromagnetic wave-transmitting member 41 attached to the bottom plate 32 of the casing body 20. The moisture percentage calculation unit 161 (see FIG. 7) calculates the moisture percentage of the biomass fuel transported by the endless belt 27 based on the microwaves received by the microwave receiving unit 45b.

Figure 3 is a schematic diagram showing another structure of a fuel delivery device provided in a biomass combustion facility according to one embodiment of the present invention. The structure of the fuel delivery device 3 is not limited to that shown in Figures 2(a) and (b), and the structures of the fuel delivery device 3 shown in Figures 3(a) to (c) may be adopted. In the following description of the structure of the fuel delivery device 3 shown in Figures 3(a) to (c), parts that are the same as or similar to the structure of the fuel delivery device 3 shown in Figures 2(a) and (b) are simply given the same reference numerals in the figures and detailed description is omitted. The following description will focus on the parts that are different from the structure of the fuel delivery device 3 shown in Figures 2(a) and (b).

In the fuel conveying device 3 shown in FIG. 3(a), a reflection-type non-contact moisture meter 48 is used, which transmits through the biomass fuel indicated by symbol M in FIG. 3(a) conveyed by the endless belt 27 in the casing body 20 and measures the moisture content of the biomass fuel by the reflected electromagnetic waves. The non-contact moisture meter 48 has a microwave transmitter/receiver 48a, which combines the functions of a microwave transmitter and a microwave receiver, and a moisture content calculator 161 (see FIG. 7). An opening 40 is formed in the top plate 31 of the casing body 20 so as to be located above the biomass fuel indicated by symbol M in FIG. 3(a) on the endless belt 27. A plate-shaped electromagnetic wave transmitting member 41 is attached to the opening 40 so as to be flush with the inner surface of the casing body 20. The microwave transmitter/receiver 48a is disposed on the back side of the electromagnetic wave transmitting member 41 attached to the top plate 31 of the casing body 20. The microwaves emitted from the microwave transmitter/receiver 48a are irradiated to the biomass fuel on the endless belt 27, indicated by the symbol M in FIG. 3(a), through the electromagnetic wave transmitting member 41 attached to the top plate 31 of the casing body 20. The irradiated microwaves penetrate the biomass fuel on the endless belt 27, are reflected at the boundary between the biomass fuel and the endless belt 27, pass through the biomass fuel on the endless belt 27 again, and are received by the microwave transmitter/receiver 48a. The moisture percentage calculation unit 161 (see FIG. 7) calculates the moisture percentage of the biomass fuel on the endless belt 27 based on the microwaves received by the microwave transmitter/receiver 48a. By adopting the reflection-type non-contact moisture meter 48, it is no longer necessary to separately provide the microwave receiver 45b provided in the fuel transport device 3 shown in FIGS. 2(a) and (b), and therefore it is no longer necessary to provide an opening 40 or an electromagnetic wave transmitting member 41 in the bottom plate 32, which simplifies the structure.

In the fuel conveying device 3 shown in FIG. 3(b), the top of the casing body 20 is open. A pair of openings 40 are formed in the left and right plates 33 and 34 of the casing body 20 so as to face each other across the biomass fuel indicated by the symbol M in FIG. 3(b) on the endless belt 27. A plate-shaped electromagnetic wave-transmitting member 41 is attached to each opening 40 so as to be flush with the inner surface of the casing body 20. The microwave transmitting unit 45a is disposed on the back side of the electromagnetic wave-transmitting member 41 attached to the left plate 33 of the casing body 20. The microwave receiving unit 45b is disposed on the back side of the electromagnetic wave-transmitting member 41 attached to the right plate 34 of the casing body 20. The microwaves transmitted from the microwave transmitting unit 45a are irradiated to the biomass fuel indicated by the symbol M in FIG. 3(b) on the endless belt 27 through the electromagnetic wave-transmitting member 41 attached to the left plate 33 of the casing body 20. The irradiated microwaves pass through the biomass fuel on the endless belt 27 and are received by the microwave receiver 45b through the electromagnetic wave transparent member 41 attached to the right side plate 34 of the casing body 20. The moisture percentage calculator 161 (see FIG. 7) calculates the moisture percentage of the biomass fuel transported by the endless belt 27 based on the microwaves received by the microwave receiver 45b.

In the fuel conveying device 3 shown in FIG. 3(c), the top of the casing body 20 is also open. In the fuel conveying device 3 shown in FIG. 3(c), a reflection-type non-contact moisture meter 48 is used. The opening 40 is formed in the right side plate 34 of the casing body 20 so as to face the biomass fuel indicated by the symbol M in FIG. 3(c) on the belt conveyor. A plate-shaped electromagnetic wave-transmitting member 41 is attached to the opening 40 so as to be flush with the inner surface of the casing body 20. The microwave transmitting/receiving unit 48a is disposed on the back side of the electromagnetic wave-transmitting member 41 attached to the right side plate 34 of the casing body 20. The microwaves transmitted from the microwave transmitting/receiving unit 48a are irradiated to the biomass fuel indicated by the symbol M in FIG. 3(c) on the endless belt 27 through the electromagnetic wave-transmitting member 41 attached to the right side plate 34 of the casing body 20. The irradiated microwaves pass through the biomass fuel on the endless belt 27, are reflected by the left side plate 33 of the casing body 20, pass through the biomass fuel on the endless belt 27 again, and are received by the microwave transmitter/receiver 48a. The moisture percentage calculation unit 161 (see FIG. 7) calculates the moisture percentage of the biomass fuel on the endless belt 27 based on the microwaves received by the microwave transmitter/receiver 48a.

In the fuel transport device 3 shown in Figures 2(a) and (b), the positions of the microwave transmitter 45a and the microwave receiver 45b may be swapped in the vertical direction. In the fuel transport device 3 shown in Figure 3(a), the electromagnetic wave transparent member 41 and the microwave transmitter/receiver 48a may be disposed on the bottom plate 32 of the casing body. In the fuel transport device 3 shown in Figure 3(b), the positions of the microwave transmitter 45a and the microwave receiver 45b may be swapped in the horizontal direction. In the fuel transport device 3 shown in Figure 3(c), the electromagnetic wave transparent member 41 and the microwave transmitter/receiver 48a may be disposed on the left side plate 33 of the casing body.

Figure 4 is a diagram illustrating devices related to condensation prevention and water droplet removal that are equipped in a fuel delivery device, where (a) is a heater, (b) is a wiper device, and (c) and (d) are air blowing devices. In the following, devices related to condensation prevention and water droplet removal for the electromagnetic wave transparent member 41 attached to the top plate 31 of the casing body 20 will be described as a representative example, but similar devices related to condensation prevention and water droplet removal can also be applied to the electromagnetic wave transparent member 41 attached to the bottom plate 32 of the casing body 20 (see Figure 2(b)), the electromagnetic wave transparent member 41 attached to the left side plate 33 (see Figure 3(b)), and the electromagnetic wave transparent member 41 attached to the right side plate 34 (see Figures 3(b) and (c)).

<Heater>
4(a) functions as a condensation prevention means for preventing condensation from occurring on the surface 41a of the electromagnetic wave transmitting member 41 on the side facing the biomass fuel in the casing 11 (casing main body 20), and as a water droplet removal means for removing water droplets attached to the surface 41a of the electromagnetic wave transmitting member 41. The heater 51 includes an electric heating wire 52 attached or embedded in an area of the electromagnetic wave transmitting member 41 through which microwaves do not pass, and is configured to be able to keep the surface of the electromagnetic wave transmitting member 41 at a temperature higher than the dew point to prevent condensation from occurring, and to dry and remove water droplets that have adhered to the surface of the electromagnetic wave transmitting member 41, by controlling the current supply to the electric heating wire 52 from a power supply unit (not shown).

<Wiper device>
As shown in Fig. 4B, a wiper device 55 is attached to the top plate 31 of the casing body 20. The wiper device 55 functions as a water droplet removing means for removing water droplets adhering to the surface 41a of the electromagnetic wave transmitting member 41. The wiper device 55 includes a device body 56 attached to the inner surface of the top plate 31 of the casing body 20, and a wiping member 57 attached to the device body 56 so as to be swingable along the surface 41a of the electromagnetic wave transmitting member 41. The wiper device 55 is configured so that the wiping member 57 can wipe off water droplets adhering to the surface 41a of the electromagnetic wave transmitting member 41 by driving the wiping member 57 to swing by operating an electric motor (not shown) built into the device body 56.

<Air blowing device>
4(c) and (d), air blowing devices 61, 61' are attached to the top plate 31 of the casing body 20. The air blowing devices 61, 61' function as condensation prevention means for preventing condensation from occurring on the surface 41a of the electromagnetic wave transparent member 41, and as water droplet removal means for removing water droplets adhering to the surface 41a of the electromagnetic wave transparent member 41.

The air blowing device 61 shown in FIG. 4(c) is configured with an air blowing nozzle 62 that blows compressed air from a compressed air supply source (not shown) along the surface 41a of the electromagnetic wave transmitting member 41. In the air blowing device 61, compressed air is constantly blown out from the air blowing nozzle 62 to form an air curtain along the surface 41a of the electromagnetic wave transmitting member 41 so that water vapor derived from the biomass fuel does not remain near the surface of the electromagnetic wave transmitting member 41, thereby preventing condensation from occurring on the surface 41a of the electromagnetic wave transmitting member 41. In addition, in the air blowing device 61, when water droplets adhere to the surface 41a of the electromagnetic wave transmitting member 41, the water droplets adhered to the surface 41a of the electromagnetic wave transmitting member 41 can be blown off and removed by blowing out compressed air from the air blowing nozzle 62.

The air blowing device 61' shown in FIG. 4(d) is configured with an air blowing nozzle 62' that blows compressed air from a compressed air supply source (not shown) toward the surface 41a of the electromagnetic wave transparent member 41. In the air blowing device 61', compressed air is blown directly from the air blowing nozzle 62' toward the surface 41a of the electromagnetic wave transparent member 41, thereby preventing condensation from forming on the surface 41a of the electromagnetic wave transparent member 41. In addition, in the air blowing device 61', when water droplets adhere to the surface 41a of the electromagnetic wave transparent member 41, compressed air is blown directly from the air blowing nozzle 62' toward the surface 41a of the electromagnetic wave transparent member 41, thereby reliably blowing off and removing the water droplets adhered to the surface 41a of the electromagnetic wave transparent member 41.

By appropriately selecting and using one or more of the devices related to condensation prevention and water droplet removal shown in Figures 4 (a) to (d), it is possible to prevent errors in moisture content measurement caused by the influence of water droplets.

<Water-repellent finish>
As shown in the enlarged view of the vicinity of the surface 41a of the electromagnetic wave transmitting member 41 in FIG. 2B, the surface 41a of the electromagnetic wave transmitting member 41 is preferably subjected to a water-repellent treatment. For example, the water-repellent treatment may be performed by forming a coating 65 made of fluororesin or silicone on the surface 41a of the electromagnetic wave transmitting member 41. In this way, by subjecting the surface 41a of the electromagnetic wave transmitting member 41 to a water-repellent treatment, the electromagnetic wave transmitting member 41 has water repellency. Even if condensation occurs on the surface 41a of the electromagnetic wave transmitting member 41, the water droplets are immediately repelled and can be prevented from adhering to the surface 41a of the electromagnetic wave transmitting member 41 as they are. Even if water droplets are attached to the surface 41a of the electromagnetic wave transmitting member 41, the adhesion of the water droplets is weak due to the effect of the water-repellent treatment, so that the water droplets can be easily and reliably removed using the wiper device 55 or the air blowing device 61, 61'. Therefore, measurement errors caused by the influence of water droplets can be suppressed.

<Combustion furnace>
As shown in FIG. 1, the combustion furnace 4 includes a furnace body 70 having a primary combustion chamber 71 and a secondary combustion chamber 72. On one side (left side in FIG. 1) of the furnace body 70, a fuel injector 75 for injecting biomass fuel into the furnace body 70 is disposed, and an auxiliary fuel supply device 76 for supplying auxiliary fuel having a higher calorific value than biomass fuel into the furnace body 70 is disposed. On the lower side of the furnace body 70, a traveling stoker 80 is disposed, and a primary combustion air supply device 91 for supplying primary combustion air to the traveling stoker 80 is disposed. In the combustion furnace 4, secondary combustion air is supplied to the secondary combustion chamber 72 by a secondary combustion air supply device 92. In the combustion furnace 4, recirculated exhaust gas is supplied to the furnace body 70 by a recirculated exhaust gas supply device 93.

<Fuel injection machine>
The fuel input device 75 includes a input device main body 77 and a radiation nozzle 78. The biomass fuel discharged from the discharge port 22 of the fuel conveying device 3 is introduced into the input device main body 77, and a part of the secondary combustion air from the secondary combustion air supply device 92 is introduced into the input device main body 77. In the fuel input device 75, the biomass fuel introduced into the input device main body 77 is discharged from the radiation nozzle 78 together with the secondary combustion air using the secondary combustion air, so that the biomass fuel can be input into the furnace main body 70. In the fuel input device 75, the flow rate of the secondary combustion air from the secondary combustion air supply device 92 introduced into the input device main body 77 is configured to be variable. With this configuration, the radiation speed when the biomass fuel is input into the furnace main body 70 can be adjusted. In addition, in the fuel input device 75, the radiation angle of the radiation nozzle 78 is configured to be variable. With this configuration, the radiation angle when the biomass fuel is input into the furnace main body 70 can be adjusted. In this way, by adjusting the radiation speed and radiation angle when the biomass fuel is charged into the furnace body 70, the charging position of the biomass fuel relative to the traveling stoker 80 can be adjusted.

<Traveling Stalker>
The traveling stoker 80 is configured by wrapping an annular grate body 83, which is formed by connecting a plurality of grates in a ring shape so that they can rotate freely, around a driving wheel 81 and a driven wheel 82 arranged at a predetermined interval in the direction in which the biomass fuel is moved, indicated by the symbol M in Fig. 1, inside the furnace body 70. A stoker driving device 85 that drives the traveling stoker 80 is attached to the traveling stoker 80. The stoker driving device 85 is configured to include a driving motor, a power transmission mechanism that transmits the rotational power of the driving motor to the driving wheel 81, and the like.

The traveling stoker 80 is arranged in the furnace body 70 so that the biomass fuel indicated by the symbol M' in FIG. 1 that is fed by the fuel feeder 75 toward the other side of the furnace body 70 (the right side in FIG. 1) can be received by the annular grate body 83. In the traveling stoker 80, the annular grate body 83 is driven to move in an orbital motion by the stoker drive device 85, and the biomass fuel from the fuel feeder 75 received by the annular grate body 83 is burned on the annular grate body 83 while moving it toward one side of the furnace body 70 (the left side in FIG. 1), and the main ash generated by the combustion can be transported to the main ash discharge port 86 provided at the bottom of one side of the furnace body 70.

A wind box 87 is attached to the lower side of the traveling stoker 80 in the furnace body 70. Primary combustion air from the primary combustion air supply device 91 is supplied to the traveling stoker 80 through the wind box 87.

<Primary combustion air supply system>
The primary combustion air supply device 91 includes a blower 111 that blows out primary combustion air, and a pipe 112 that guides the primary combustion air from the blower 111 to the wind box 87, and is configured so that the primary combustion air from the blower 111 can be supplied to the wind box 87 via the pipe 112. A flow rate adjustment damper device 113 is provided in the pipe 112.

<Secondary combustion air supply device>
The secondary combustion air supply device 92 includes a blower 121 for blowing out secondary combustion air, a main duct 122 through which the secondary combustion air from the blower 121 flows, and a first branch duct 122a and a second branch duct 122b branching from the main duct 122. The first branch duct 122a is connected to the secondary combustion chamber 72 in the furnace body 70 from one side (left side in FIG. 1) of the furnace body 70 via a fuel input device 75. The second branch duct 122b is connected to the secondary combustion chamber 72 in the furnace body 70 from the other side (right side in FIG. 1) of the furnace body 70. The secondary combustion air supply device 92 is configured so that the secondary combustion air from the blower 121 can be supplied into the secondary combustion chamber 72 via the main duct 122, the first branch duct 122a, and the second branch duct 122b.

A main flow rate control damper device 123 is provided in the main line 122. A first flow rate control damper device 124 and a second flow rate control damper device 125 are provided in the first branch line 122a and the second branch line 122b, respectively.

<Recirculating exhaust gas supply device>
The recirculated exhaust gas supply device 93 includes a blower 131 that blows out a portion of the low-temperature exhaust gas discharged from a chimney (not shown) into the atmosphere as recirculated exhaust gas, and a blower 132 that blows the recirculated exhaust gas from the blower 131 into the furnace body 70. The recirculated exhaust gas from the blower 131 can be supplied into the furnace body 70 through the pipe 132. The pipe 132 is provided with a flow rate control damper device 133. is installed.

Figure 5 is a block diagram showing the schematic configuration of a combustion control system in a biomass combustion facility according to one embodiment of the present invention. The biomass combustion facility 1 is equipped with a combustion control system 150 as shown in Figure 5. This combustion control system 150 is configured with a control device 151 mainly composed of a microcomputer incorporating a CPU 151a, memory 151b, an I/O port 151c, etc., and various devices 152 connected to the control device 151 so as to be able to transmit signals. The various devices 152 include a conveyor drive device 15, a non-contact moisture meter 45, 48, a fuel input device 75, an auxiliary fuel supply device 76, a stoker drive device 85, a flow rate adjustment damper device 113 related to the primary combustion air supply, flow rate adjustment damper devices 123 to 125 related to the secondary combustion air supply, and a flow rate adjustment damper device 133 related to the recirculated exhaust gas supply.

In the control device 151, the memory 151b stores predetermined programs and the like required to control the various devices 152, data on the positive correlation between the amplitude and phase ratio (amplitude-phase ratio) and the official moisture content (dry weight method) as shown in FIG. 6, which is related to the microwaves received by the microwave receivers 45b, 105b (microwave transmitters and receivers 48a, 108a) for the microwaves transmitted from the microwave transmitters 45a, 105a (microwave transmitters and receivers 48a, 108a), and other data required for combustion control, etc. In the control device 151, the CPU 151a reads the predetermined programs and various data stored in the memory 151b and executes predetermined processing, thereby exerting the functions of the various functional units as shown in the functional block diagram of FIG. 7.

Figure 7 is a functional block diagram of a combustion control system in a biomass combustion facility according to one embodiment of the present invention. The various functional parts of the control device 151 shown in the functional block diagram of Figure 7 include a moisture percentage calculation part 161, a conveyor control part 162, a fuel control part 163, a stoker control part 164, a damper control part 165, and a memory part 166.

When a non-contact moisture meter 45 of the transmission type is used, the moisture content calculation unit 161 reads from the memory unit 166 data (see FIG. 6) on the positive correlation between the amplitude phase ratio and the official moisture content (dry weight method) for the microwaves received by the microwave receiving unit 45b relative to the microwaves transmitted by the microwave transmitting unit 45a, which data is stored in advance in the memory unit 166, and calculates the moisture content of the biomass fuel based on the read data and the microwaves received by the microwave receiving unit 45b.

When a reflective non-contact moisture meter 48 is used, the moisture content calculation unit 161 reads from the memory unit 166 data (see FIG. 6) on the positive correlation between the amplitude phase ratio and the official moisture content (dry weight method) for the microwaves received by the microwave transmitter/receiver 48a relative to the microwaves transmitted from the microwave transmitter/receiver 48a, which data is stored in advance in the memory unit 166, and calculates the moisture content of the biomass fuel based on the read data and the microwaves received by the microwave transmitter/receiver 48a.

The conveyor control unit transmits a predetermined control signal to the conveyor drive unit 15 based on the moisture content calculated by the moisture content calculation unit 161. This controls the transport speed and transport timing of the biomass fuel by the fuel transport device 3 to the fuel input device 75.

The fuel control unit 163 transmits a predetermined control signal to the fuel injector 75 based on the moisture percentage calculated by the moisture percentage calculation unit 161. This adjusts the radiation speed and radiation angle when the biomass fuel is injected into the furnace body 70, and controls the biomass fuel injection position, etc. The fuel control unit 163 also transmits a predetermined control signal to the auxiliary fuel supply device 76 based on the moisture percentage calculated by the moisture percentage calculation unit 161. This makes it possible to supply auxiliary fuel with a greater calorific value than the biomass fuel into the furnace body 70 as necessary.

The stoker control unit 164 transmits a predetermined control signal to the stoker drive device 85 based on the moisture content calculated by the moisture content calculation unit 161. This controls the speed at which the biomass fuel moves within the furnace body 70 by the annular grate body 83 in the traveling stoker 80.

The damper control unit 165 transmits a predetermined control signal to each flow rate adjustment damper device 113, 123 to 125, and 133 based on the moisture percentage calculated by the moisture percentage calculation unit 161. This controls the supply amount of primary combustion air, secondary combustion air, and recirculated exhaust gas.

The memory unit 166 functions as a storage for holding data used when the CPU 151a performs a predetermined calculation process, such as data on the positive correlation between the amplitude phase ratio and the official moisture content (dry weight method) for microwaves received by the microwave receivers 45b, 105b (microwave transmitters and receivers 48a, 108a) in response to microwaves transmitted from the microwave transmitters 45a, 105a (microwave transmitters and receivers 48a, 108a) (see FIG. 6), and other data necessary for combustion control, etc.

In the biomass combustion equipment 1 configured as described above, combustion in the combustion furnace 4 is controlled as follows. That is, in the fuel transport device 3, the moisture content of the biomass fuel transported by the belt conveyor 13 inside the casing main body 20 is measured by the non-contact moisture meter 45 (moisture content measurement process). Based on the measurement results of the moisture content of the biomass fuel, the conveyor control unit 162, the fuel control unit 163, the stoker control unit 164, and the damper control unit 165 control combustion in the combustion furnace 4 as exemplified below (combustion state control process).

For example, if an increasing trend in the heat generation rate of biomass fuel can be predicted from the measurement results of the moisture content of the biomass fuel, before biomass fuel with a large heat generation rate is supplied to the furnace body 70, the conveyor control unit 162 sends a predetermined control signal to the conveyor drive device 15 to reduce the amount of biomass fuel transported to the fuel input device 75, and adjusts the transport speed of the belt conveyor 13, etc., to reduce the amount of biomass fuel transported by the belt conveyor 13. This makes it possible to suppress excessive combustion and stabilize the combustion operation.

For example, if a decreasing trend in the heat generation rate of biomass fuel can be predicted from the measurement results of the moisture content of the biomass fuel, a predetermined control signal is sent to the fuel input device 75 to adjust the rate at which the biomass fuel is sprayed into the furnace body 70 by the fuel input device 75. In this way, the biomass fuel input from the fuel input device 75 into the furnace body 70 is concentrated and dropped at a position on the annular grate body 83 that is suitable for combustion in the furnace body 70. This makes it possible to prevent biomass fuel with a low heat generation rate when the moisture content is high from burning sluggishly on the annular grate body 83, stabilizing the combustion operation.

For example, if an increasing trend in the heat generation rate of the biomass fuel can be predicted from the measurement results of the moisture content of the biomass fuel, the stoker control unit 164 sends a predetermined control signal to the stoker drive device to adjust the feed rate of the biomass fuel through the annular grate body 83. This changes the feed rate of the biomass fuel through the annular grate body 83. This makes it possible to suppress excessive combustion and stabilize the combustion operation.

For example, if an increasing trend in the heat generation rate of biomass fuel can be predicted from the measurement results of the moisture content of the biomass fuel, the damper control unit 165 sends a predetermined control signal to the flow rate control damper device 133 to adjust the supply amount of recirculated exhaust gas so that the temperature inside the furnace body 70 changes, and changes the damper opening of the flow rate control damper device 133. This makes it possible to suppress excessive combustion and stabilize the combustion operation.

For example, if a decreasing trend in the heat generation rate of biomass fuel can be predicted from the measurement results of the moisture content of the biomass fuel, before biomass fuel with a low heat generation rate is supplied to the furnace body 70, the damper control unit 165 sends a predetermined control signal to each flow rate adjustment damper device 113, 123-125 to adjust the amount of combustion air supplied so that the temperature in the combustion chambers 71, 72 changes, and changes the damper opening of each flow rate adjustment damper device 113, 123-125. This makes it possible to prevent combustion from becoming sluggish, and stabilize the combustion operation.

For example, if a decreasing trend in the heat generation rate of the biomass fuel can be predicted from the measurement results of the moisture content of the biomass fuel, the stoker control unit 164 transmits a predetermined control signal to the stoker drive device 85 to adjust the feed rate of the biomass fuel through the annular grate body 83. This changes the feed rate of the biomass fuel through the annular grate body 83. This makes it possible to prevent combustion from becoming sluggish, and stabilize the combustion operation.

The combustion controls exemplified above may be combined as appropriate.

The combustion control described above stabilizes the temperature and exhaust gas volume inside the furnace body 70, stabilizing combustion operation. Stabilizing combustion operation stabilizes the amount of steam generated in the boiler 5, and therefore the amount of heat recovered. Furthermore, stabilizing combustion operation keeps the load on various equipment constant, reducing equipment wear and the amount of operation. Reducing the amount of operation reduces power costs. Furthermore, by automating combustion control and utilizing the learning functions of AI (artificial intelligence), more optimal combustion operation can be achieved, making it possible to significantly reduce operating costs.

In addition, in the biomass combustion equipment 1, non-contact moisture meters 45, 48 are used to measure the moisture content of the biomass fuel based on correlation data between the amplitude phase ratio of the electromagnetic waves transmitted through the biomass fuel and the official moisture content. By measuring the moisture content based on the amplitude phase ratio in this way, accurate measurement values can be obtained regardless of the thickness of the measurement object (biomass fuel) transported by the fuel transport device 3.

The biomass combustion facility of the present invention has been described above based on one embodiment, but the present invention is not limited to the configuration described in the above embodiment, and the configuration can be changed as appropriate within the scope of the spirit of the invention. Specific alternative embodiments are as follows.

Figure 8 is a schematic diagram illustrating another embodiment of the biomass combustion facility of the present invention.

[Another embodiment (1)]
In another embodiment (1) shown in Fig. 8(a), two or more kinds of biomass fuels are used, and each biomass fuel is transported separately to a fuel input device 75 via each fuel transport device 3 installed corresponding to each biomass fuel, and the biomass fuel is input from each fuel input device 75 into the furnace body 70. In this case, as exemplified above, combustion in the combustion furnace 4 is controlled based on the measurement results from the non-contact moisture meter 45 (48) disposed in each fuel transport device 3.

[Another embodiment (2)]
In another embodiment (2) shown in Fig. 8(b), two or more kinds of biomass fuels are used, and are transported by the respective fuel transport devices 3 installed corresponding to the respective biomass fuels, and the mixed biomass fuel mixed in the mixer 170 arranged between the respective fuel transport devices 3 and the fuel input device 75 is transported to the fuel input device 75. In addition, in the another embodiment (2), a non-contact moisture meter 45 (48) is arranged to measure the moisture content of the mixed biomass fuel after being mixed in the mixer 170. In this case, the mixing ratio of the biomass fuel in the mixer 170 is adjusted based on the measurement result by the non-contact moisture meter 45 (48), and the combustion in the combustion furnace 4 is controlled according to the moisture content of the mixed biomass fuel, as exemplified above.

[Another embodiment (3)]
In another embodiment (3) shown in Fig. 8(c), similarly to the another embodiment (2), two or more kinds of biomass fuels are used, and are transported by respective fuel transport devices 3 installed corresponding to the respective biomass fuels, and mixed biomass fuel mixed in a mixer 170 disposed between each fuel transport device 3 and a fuel input device 75 is transported to the fuel input device 75. In another embodiment (3), a non-contact moisture meter 45 (48) is disposed in each fuel transport device 3, and a non-contact moisture meter 45 (48) is disposed to measure the moisture content of the mixed biomass fuel after being mixed in the mixer 170. In this case, the moisture percentage of each biomass fuel before mixing is measured using a non-contact moisture meter 45 (48) arranged in each fuel transport device 3, and the optimum mixing ratio of each biomass fuel for making the moisture percentage of the mixed biomass fuel a desired value is calculated based on the measurement result, and each biomass fuel is introduced into the mixer 170 according to the calculated mixing ratio, and each introduced biomass fuel is mixed in the mixer 170. In this way, the moisture percentage of the mixed biomass fuel can be made close to the desired moisture percentage. Then, the actual moisture percentage of the mixed biomass fuel is measured using a non-contact moisture meter 45 (48) arranged for measuring the moisture percentage of the mixed biomass fuel, and the combustion in the combustion furnace 4 is controlled based on the measurement result as exemplified above.

[Another embodiment (4)]
In the above embodiment, an example in which a belt conveyor type is adopted as the fuel transport device 3 is shown, but the invention is not limited thereto, and a flight conveyor type may be adopted. A detailed description of the flight conveyor type fuel transport device will be omitted with reference to the drawings, but a brief description will be given below. The flight conveyor type fuel transport device is configured by arranging a flight conveyor in a casing having the same structure as the above casing 11. The flight conveyor includes drive wheels and driven wheels arranged at a predetermined interval in the transport direction, an endless chain wrapped around the drive wheels and driven wheels, a plurality of scrapers attached to the endless chain at predetermined intervals so as to be movable in close proximity to the bottom plate of the casing, and a drive motor for driving the drive wheels. In this flight conveyor, biomass fuel is dropped onto the bottom plate of the casing through an inlet of the casing, and the biomass fuel on the bottom plate of the casing is scraped off by a scraper attached to the endless chain driven to move in a circular motion by the operation of the drive motor, and transported to the discharge outlet of the casing.

[Another embodiment (5)]
The combustion furnace 4 may be a stepped stoker type combustion furnace, a fluidized bed combustion furnace, or a circulating fluidized bed combustion furnace.

The biomass combustion equipment and biomass combustion method of the present invention can be used, for example, to stabilize the combustion operation of biomass fuels such as wood-based biomass fuels, plant-based biomass fuels, and livestock biomass fuels.

REFERENCE SIGNS LIST 1 Biomass combustion equipment 3 Fuel transport device 4 Combustion furnace 11 Casing 40 Opening 41 Electromagnetic wave transparent member 45 Non-contact moisture meter (transmission type)
48 Non-contact moisture meter (reflection type)
51 Heater (means for preventing condensation, means for removing water droplets)
55 Wiper device (water droplet removal means)
61, 61' Air blowing device (condensation prevention means, water droplet removal means)
65 Coating 71, 72 Combustion chamber 75 Fuel input device 83 Annular fire grate body 113 Flow rate adjustment damper device (damper for primary combustion air)
123-125 Flow rate control damper device (damper for secondary combustion air)
133 Flow rate control damper device (damper for recirculated exhaust gas)

Claims (5)

A biomass combustion facility configured to combust biomass fuel transported by a fuel transport device in a combustion chamber of a combustion furnace,
A non-contact moisture meter is provided for measuring the moisture content of biomass fuel by irradiating the biomass fuel with electromagnetic waves ,
The fuel conveying device includes:
A casing for containing biomass fuel;
an electromagnetic wave transmitting member attached to an opening provided in the casing;
Equipped with
The biomass fuel in the casing is irradiated with electromagnetic waves through the electromagnetic wave transparent member.
A biomass combustion facility equipped with an air blowing device comprising an air blowing nozzle that blows compressed air along the surface of the electromagnetic wave transparent member facing the biomass fuel in the casing, or an air blowing nozzle that blows compressed air toward the surface . The biomass combustion facility according to claim 1 , wherein the electromagnetic wave transparent member is water repellent. The combustion furnace has at least one of a fuel input device that inputs the biomass fuel transported from the fuel transport device into the combustion chamber, a fire grate that transports the biomass fuel within the combustion chamber, a combustion air damper that adjusts the amount of combustion air supplied to the combustion chamber, and a recirculated exhaust gas damper that adjusts the amount of recirculated exhaust gas supplied to the combustion chamber,
3. The biomass combustion facility according to claim 1 or 2, further comprising a combustion state control means for adjusting at least one of the following, depending on the moisture percentage measured by the non-contact moisture meter: the biomass fuel transport speed by the fuel transport device, the biomass fuel input position by the fuel input device, the biomass fuel feed speed by the grate , the amount of combustion air supplied by the combustion air damper, and the amount of recirculated exhaust gas supplied by the recirculated exhaust gas damper. The biomass combustion facility according to any one of claims 1 to 3, wherein the non-contact moisture meter is a transmission type non-contact moisture meter that measures the moisture content of the biomass fuel by electromagnetic waves that pass through the biomass fuel. The biomass combustion facility according to any one of claims 1 to 3, wherein the non-contact moisture meter is a reflective non-contact moisture meter that measures the moisture content of the biomass fuel by electromagnetic waves that pass through the biomass fuel and are reflected.

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