Combustion furnace system, and method of combusting biomass fuel

Abstract

To materialize a combustion furnace system easily securing that biomass fuel to be combusted is in a suitable state of combustion, and a method of combusting biomass fuel.SOLUTION: The combustion system comprises a combustion device 2 using biomass fuel T as fuel, a dryer 32 drying the biomass fuel T, and a feeder 7 feeding heat medium gas including at least one of the exhaust from the combustion device 2 and gas heated by exchanging heat with the exhaust to the dryer 32. The feeder 7 controls at least one of the flow-rate and the temperature of the heat medium gas to be fed to the dryer 32, according to the moisture content in the biomass fuel T.SELECTED DRAWING: Figure 1

Description

Technical Field

[0001] The present invention relates to a combustion furnace system and a method for burning biomass fuel.

Background Art

[0002] As a means to reduce the dependence on fossil fuels and suppress the progress of environmental problems such as global warming, biomass fuel has attracted attention. By using biomass fuel instead of fossil fuel, the consumption of fossil fuel can be suppressed.

[0003] In many cases, since biomass fuel contains moisture, it is necessary to perform drying prior to use as fuel. For example, Japanese Patent Application Laid-Open No. 2011-112228 (Patent Document 1) discloses an invention in which biomass fuel is dried using the combustion gas of a steam boiler in a steam boiler using biofuel as fuel. Further, Japanese Patent Application Laid-Open No. 2013-47593 (Patent Document 2) discloses an invention related to a boiler system that dries biomass fuel using the waste heat of a boiler device.

Prior Art Documents

Patent Documents

[0004]

Patent Document 1

Patent Document 2

Summary of the Invention

Problems to be Solved by the Invention

[0005] In each of the inventions of Patent Document 1 and Patent Document 2, a configuration is adopted in which the dried biomass fuel is stored and then supplied to a combustion device such as a steam boiler. In these configurations, there is a risk that the stored biomass fuel absorbs moisture again and becomes unsuitable for combustion.

[0006] Therefore, it is desired to realize a combustion furnace system and a method for burning biomass fuel that can easily ensure that the biomass fuel used for combustion is in a state suitable for combustion.

Means for Solving the Problems

[0007] A first combustion furnace system according to the present invention includes a combustion device that uses biomass fuel as fuel, a drying unit that dries the biomass fuel, and a supply device that supplies a heat medium gas including at least one of the exhaust gas of the combustion device and a gas heated by heat exchange with the exhaust gas to the drying unit. The supply device is characterized in that it controls at least one of the flow rate and temperature of the heat medium gas supplied to the drying unit based on the moisture content of the biomass fuel.

[0008] A first method for burning biomass fuel according to the present invention includes a combustion step of burning biomass fuel, and a drying step of drying the biomass fuel using a heat medium gas including at least one of the exhaust gas generated in the combustion step and a gas heated by heat exchange with the exhaust gas. The method is characterized in that it controls at least one of the flow rate and temperature of the heat medium gas based on the moisture content of the biomass fuel.

[0009] According to these configurations, since the degree of drying is adjusted based on the moisture content of the biomass fuel supplied to the combustion device, it is easy to ensure that the biomass fuel used for combustion is in a state suitable for combustion.

[0010] A second combustion furnace system according to the present invention includes a combustion device that uses biomass fuel as fuel, a storage unit that stores the biomass fuel, a drying unit that dries the biomass fuel between the storage unit and the combustion device, and a supply device that supplies a heat medium gas including at least one of the exhaust gas of the combustion device and a gas heated by heat exchange with the exhaust gas to the drying unit.

[0011] The method for burning a second biomass fuel according to the present invention is a method for burning a biomass fuel using a combustion furnace system including a combustion device using the biomass fuel as fuel and a storage unit for storing the biomass fuel, and drying the biomass fuel using a heat medium gas including at least one of the exhaust gas of the combustion device and the gas heated by heat exchange with the exhaust gas between the storage unit and the combustion device. It is characterized by including a drying step.

[0012] According to these configurations, since the stored biomass fuel is dried midway through being supplied to the combustion device, it is easy to ensure that the biomass fuel used for combustion is in a state suitable for combustion.

[0013] Hereinafter, preferred embodiments of the present invention will be described. However, the scope of the present invention is not limited by the preferred embodiment examples described below.

[0014] As one aspect, the first combustion furnace system according to the present invention further includes a measuring device for measuring the moisture content of the biomass fuel supplied to the combustion device, and it is preferable that the supply device controls at least one of the flow rate and temperature of the heat medium gas supplied to the drying unit based on the moisture content measured by the measuring device.

[0015] According to this configuration, since the degree of drying is adjusted based on the measured value of the moisture content of the biomass fuel, it is even easier to ensure that the biomass fuel used for combustion is in a state suitable for combustion.

[0016] As one aspect, the first combustion furnace system according to the present invention further includes a storage unit for storing the biomass fuel, and it is preferable that the drying unit is provided between the storage unit and the combustion device.

[0017] According to this configuration, since the stored biomass fuel is dried midway through being supplied to the combustion device, it is easy to ensure that the biomass fuel used for combustion is in a state suitable for combustion.

[0018] In one aspect, the combustion furnace system according to the present invention preferably has a blowout port through which the heat medium gas blows out in the drying section.

[0019] According to this configuration, biomass fuel can be efficiently dried.

[0020] In one aspect, the combustion furnace system according to the present invention preferably has the blowout port at least on the floor surface in the drying section.

[0021] According to this configuration, since the heat medium gas can be supplied from below the biomass fuel to be dried, the moisture separated from the biomass fuel is easily removed together with the upward airflow. Therefore, the biomass fuel can be dried more efficiently.

[0022] In one aspect, the combustion furnace system according to the present invention preferably includes a storage device having the storage section and the drying section.

[0023] According to this configuration, since the storage section and the drying section are provided as an integrated storage device, the installation area of the equipment can be suppressed.

[0024] Further features and advantages of the present invention will become more apparent from the following description of exemplary and non-limiting embodiments with reference to the drawings.

Brief Description of the Drawings

[0025]

Figure 1

Embodiments for Carrying Out the Invention

[0026] Embodiments of a combustion furnace system and a method for burning biomass fuel according to the present invention will be described with reference to the drawings. Hereinafter, an example in which the present invention is applied to a combustion furnace system 1 that burns wood chips T (an example of biomass fuel), and a method for burning wood chips T using the combustion furnace system 1 will be described.

[0027] 〔Configuration of Combustion Furnace System〕 The combustion furnace system 1 according to the present embodiment includes a combustion device 2, a storage device 3, a conveying device 4, a measuring device 5, a heat utilization device 6, and a supply device 7 (FIG. 1). The combustion furnace system 1 is generally a system that burns wood chips T stored in the storage device 3 in the combustion device 2 and utilizes the combustion heat in the heat utilization device 6.

[0028] The combustion device 2 is a combustion device that uses wood chips T as fuel, and a known combustion furnace or the like suitable for burning wood chips T can be used. Examples of such combustion furnaces include, but are not limited to, stoker-type and fluidized-bed combustion furnaces. The combustion gas generated by the combustion of wood chips T is sent to the heat utilization device 6 as exhaust.

[0029] The storage device 3 is a device that stores wood chips T used as fuel in the combustion device 2. The storage device 3 has a storage unit 31 that functions as a main space for storing wood chips T, and a drying unit 32 that dries wood chips T. Note that the storage unit 31 and the drying unit 32 are divisions of the internal space of the storage device 3 according to their functions, but do not have a clear boundary between them.

[0030] Further, the storage device 3 has a moving bed 33 on the floor surface of its internal space for conveying wood chips T. The moving bed 33 is provided across the storage unit 31 and the drying unit 32, and conveys wood chips T in the direction from the storage unit 31 to the drying unit 32. Hereinafter, the front-rear direction of the storage device 3 is defined according to the conveying direction of wood chips T by the moving bed 33. That is, the storage unit 31 is arranged at the rear of the storage device 3, and the drying unit 32 is arranged at the front of the storage device 3.

[0031] The drying section 32 has a blowout port 34 on the floor surface from which a heat medium gas, which will be described later, blows out, and an exhaust fan 35 for discharging the heat medium gas to the outside of the apparatus on the ceiling. In the drying section 32, a flow of the heat medium gas from the blowout port 34 toward the exhaust fan 35 is formed, and the wood chips T are heated and dried by contact with the heat medium gas. Note that the exhaust fan 35 also serves to discharge the moisture (water vapor) separated from the wood chips T to the outside of the apparatus and form an atmosphere in which the drying of the wood chips T proceeds easily. The front end of the drying section 32 is connected to the conveying device 4, and the wood chips T that have fallen from the front end of the drying section 32 are supplied to the combustion device 2 by the conveying device 4.

[0032] The wood chips T are gradually conveyed by the moving bed 33 from the rear to the front of the storage device 3, and eventually fall from the front end of the drying section 32 and reach the conveying device 4. The wood chips T received from the fuel hopper (not shown) by the storage device 3 are put into the rear part of the storage section 31 and sequentially sent to the drying section 32 by the moving bed 33. The wood chips T are heated by the heat medium gas while passing through the drying section 32, and after being gradually dried, they fall from the front end of the drying section 32 to the conveying device 4.

[0033] The conveying device 4 is a device that supplies the wood chips T from the storage device 3 to the combustion device 2. As the conveying device 4, a known device suitable for conveying the wood chips T may be used, and for example, a belt conveyor or the like may be used.

[0034] The measuring device 5 is a device that measures the moisture content of the wood chips T supplied to the combustion device 2. In the present embodiment, the measuring device 5 is installed in the conveying device 4, and the moisture content of the wood chips T conveyed by the conveying device 4 is measured. Since this wood chips T has reached the conveying device 4 after being dried in the drying section 32, it can be said that the measuring device 5 measures the moisture content of the wood chips T dried in the drying section 32.

[0035] The heat utilization device 6 is a device that utilizes the combustion heat generated by the combustion of wood chips T in the combustion device 2. Taking the case where the heat utilization device 6 is a boiler and auxiliary devices as an example, the heat utilization device 6 has, in order from the upstream side (the combustion device 2 side), a boiler 61, an economizer 62, and a cyclone 63. The boiler 61 is a device that heats water by heat exchange with the combustion gas (exhaust gas of the combustion device 2) supplied from the combustion device 2 to generate steam, and generates steam by utilizing the combustion heat. The economizer 62 is a device that preheats water by heat-exchanging the combustion gas discharged from the boiler 61 and the water before being supplied to the boiler 61, and is an example of an auxiliary device. The cyclone 63 is a device that recovers the solid content contained in the combustion gas discharged from the economizer 62, and is an example of an auxiliary device. As the boiler 61, the economizer 62, and the cyclone 63, those known as such devices can be used respectively.

[0036] Downstream of the heat utilization device 6 (cyclone 63), a chimney C that discharges the combustion gas (exhaust gas) to the outside of the system and an exhaust pipe P that connects the cyclone 63 and the chimney C are provided.

[0037] The supply device 7 is a device that supplies a heat medium gas that serves as a heat medium for heating the wood chips T in the drying unit 32. The supply device 7 has a heat medium pipe 71 through which the heat medium gas flows, a suction fan 72 that draws air into the heat medium pipe 71, a heat exchanger 73 provided across the heat medium pipe 71 and the exhaust pipe P, a damper 74 provided in the middle of the heat medium pipe 71, and a blower fan 75 that sends the heat medium gas to the drying unit 32.

[0038] In this embodiment, as the heat transfer medium gas, air (an example of a gas) heated by heat exchange with the exhaust gas of the combustion device 2 is used. The air drawn into the heat transfer medium pipe 71 by the suction fan 72 is heated by heat exchange with the exhaust gas flowing through the exhaust pipe P in the heat exchanger 73. The heated air (heat transfer medium gas) is distributed by the damper 74 to a path leading to the drying section 32 via the air supply fan 75 and a path leading outside the system. The heat transfer medium gas that has reached the drying section 32 is blown out from the air outlet 34. Note that the damper 74 and the air supply fan 75 are electrically connected to the measuring device 5.

[0039] 〔Control of Combustion Furnace System〕 Next, the control of the combustion furnace system 1 will be described.

[0040] Combustion furnaces and the like used as the combustion device 2 have different suitable ranges for the moisture content of the fuel depending on their specifications. Therefore, in order to operate the combustion furnace system 1 efficiently, it is desirable to supply wood chips T with a moisture content suitable for the specifications of the combustion device 2.

[0041] Therefore, in this embodiment, the moisture content of the wood chips T supplied to the combustion device 2 is measured by the measuring device 5 provided in the conveying device 4, and the degree of drying in the drying section 32 is adjusted so that the moisture content becomes an appropriate value in view of the specifications of the combustion device 2. Specifically, based on the measured value of the measuring device 5, at least one of the opening degree of the damper 74 and the output of the air supply fan 75 is controlled to control the flow rate of the heat transfer medium gas blown out from the air outlet 34, thereby adjusting the degree of drying in the drying section 32.

[0042] 〔Other Embodiments〕 Finally, other embodiments of the combustion furnace system and the method for burning biomass fuel according to the present invention will be described. Note that the configurations disclosed in the following respective embodiments can be applied in combination with the configurations disclosed in other embodiments as long as no contradiction occurs.

[0043] In the above-described embodiment, a configuration in which air heated by heat exchange with the exhaust gas of the combustion device 2 is used as the heat medium gas has been described as an example. However, as the heat medium gas in the present invention, instead of or in addition to the gas heated by heat exchange with the exhaust gas of the combustion device, the exhaust gas of the combustion device itself may be used.

[0044] In the above-described embodiment, a configuration in which the flow rate of the heat medium gas blown out from the blowout port 34 is controlled based on the measurement value of the measuring device 5 has been described as an example. However, in the first combustion furnace system according to the present invention, instead of or in addition to the flow rate of the heat medium gas, the temperature of the heat medium gas may be controlled. In this case, a temperature measuring device for measuring the temperature of the heat medium gas may be provided.

[0045] In the above-described embodiment, a configuration in which the measuring device 5 is installed in the conveying device 4 has been described as an example. However, in the first combustion furnace system according to the present invention, the method for specifying the moisture content of the biomass fuel is not limited to the above-described aspect. For example, a method of estimating the moisture content of the biomass fuel from the past operation results of the combustion furnace system, a method of using the value of the moisture content measured in advance outside the combustion furnace system, etc. are exemplified. Therefore, the first combustion furnace system according to the present invention only needs to be provided with means corresponding to the method for specifying the moisture content, and the measuring device is only one example. Further, when the measuring device is provided, its position is not limited as long as it can measure the moisture content of the biomass fuel supplied to the combustion device. Therefore, the measuring device may be provided, for example, at the inlet of the biomass fuel in the combustion device, or may be provided at the outlet of the storage unit in a configuration where a storage unit is provided.

[0046] In the above-described embodiment, a configuration including the storage device 3 having the storage unit 31 and the drying unit 32 has been described as an example. However, in the second combustion furnace system according to the present invention, the storage unit and the drying unit may be incorporated into an integrated device or may exist as separate devices.

[0047] In the above-described embodiment, the configuration in which the drying section 32 has air outlets 34 on the floor surface and the wood chips T are dried by the heat medium gas blown out from the air outlets 34 was described as an example. However, in the present invention, the method of drying biomass fuel using heat medium gas is not limited.

[0048] In the above-described embodiment, the configuration in which wood chips T are used as the biomass fuel was described as an example. However, the biomass fuel used in the present invention is not limited to wood chips. Examples of biomass fuel include, for example, food residues (such as coffee grounds, wheat bran, green tea bran, sake lees, and pomace of fruits such as grapes). Note that, depending on the properties of the biomass fuel used, etc., the specifications of the combustion device, drying section, etc. can be appropriately changed.

[0049] Regarding other configurations as well, it should be understood that the embodiments disclosed in this specification are illustrative in all respects and the scope of the present invention is not limited thereby. Those skilled in the art will easily understand that appropriate modifications can be made without departing from the spirit of the present invention. Therefore, other embodiments modified without departing from the spirit of the present invention are naturally included in the scope of the present invention.

Examples

[0050] Hereinafter, the present invention will be further described by showing examples. Note that the following examples do not limit the present invention.

[0051] 〔Test apparatus〕 As a jet heater for generating hot air, a hot gun HGDHII-T (manufactured by Shizuoka Seiki Co., Ltd.) was used. As an air supply fan for sending hot air to the wood chips, an EBARA FAN No.3 APM (manufactured by Ebara Corporation) was used. As a moisture content measuring device, a humimeter BLL (manufactured by BEA Institut fuer Bioenergie GmbH) was used.

[0052] 〔Example 1〕 Hot air at 40°C was blown from the side of a sample block formed by stacking wood chips to a height of approximately 1.5 m to dry the wood chips. Only one air blower was used. The moisture content of the wood chips was measured before the start of drying and every 30 minutes during drying. The moisture content was measured by collecting samples from three points with different heights in the sample block, and the average value of the moisture contents at these three points was taken as the measured value. The above test was carried out until 150 minutes after the start of drying.

[0053] 〔Example 2〕 A test was conducted in the same manner as in Example 1, except that in addition to blowing hot air from the side of the sample block, hot air was also blown from below the sample block. The supply of hot air from below the sample block was carried out by connecting a vinyl chloride pipe having an air outlet with a diameter of 70 mm on the side to an air blower and inserting 1 m of the pipe under the sample block. There were seven air outlets provided in the portion inserted under the sample block, and two air blowers were used.

[0054] 〔Test Results〕 The test results of Example 1 and Example 2 are shown in Table 1. In any of the examples, the moisture content of the wood chips decreased with the passage of time. In Example 2 where hot air was supplied from the side and below the test block, the decrease in moisture content was particularly significant.

[0055] Table 1: Examples

Table 1

Industrial Applicability

[0056] The present invention can be used, for example, as a combustion furnace system using wood chips as fuel and its operation method.

Explanation of Signs

[0057] 1: Combustion furnace system 2: Combustion device 3: Storage device 31: Storage section 32: Drying section 33: Moving bed 34: Air outlet 35: Exhaust fan 4: Conveyor 5: Measuring device 6: Heat utilization device 61: Boiler 62: Economizer 63: Cyclone 7: Feeding device 71: Heat medium pipe 72: Suction fan 73: Heat exchanger 74: Damper 75: Air supply fan T: Wood chips C: Chimney P: Exhaust pipe

Claims

1. A combustion device using biomass fuel as fuel, A drying unit for drying the biomass fuel, A supply device for supplying a heat medium gas containing at least one of the exhaust gas of the combustion device and the gas heated by heat exchange with the exhaust gas to the drying unit, A combustion furnace system in which the supply device controls at least one of the flow rate and temperature of the heat medium gas supplied to the drying unit based on the moisture content of the biomass fuel.

2. A combustion device using biomass fuel as fuel, A storage unit for storing the biomass fuel, A drying unit for drying the biomass fuel between the storage unit and the combustion device, A combustion furnace system including a supply device for supplying a heat medium gas containing at least one of the exhaust gas of the combustion device and the gas heated by heat exchange with the exhaust gas to the drying unit.

3. Further comprising a measuring device for measuring the moisture content of the biomass fuel supplied to the combustion device, The combustion furnace system according to claim 1, wherein the supply device controls at least one of the flow rate and temperature of the heat medium gas supplied to the drying unit based on the moisture content measured by the measuring device.

4. Further comprising a storage unit for storing the biomass fuel, The combustion furnace system according to claim 1, wherein the drying unit is provided between the storage unit and the combustion device.

5. The combustion furnace system according to any one of claims 1 to 4, wherein the drying unit has a blowout port from which the heat medium gas blows out.

6. The combustion furnace system according to claim 5, wherein the drying unit has the blowout port at least on the floor surface.

7. The combustion furnace system according to claim 2 or 4, comprising a storage device having the storage unit and the drying unit.

8. A combustion step of burning biomass fuel; A drying step of drying the biomass fuel using a heat medium gas containing at least one of the exhaust gas generated in the combustion step and the gas heated by heat exchange with the exhaust gas; A method for burning biomass fuel, which controls at least one of the flow rate and temperature of the heat medium gas based on the moisture content of the biomass fuel.

9. A method for burning biomass fuel, which burns the biomass fuel using a combustion furnace system including a combustion device using the biomass fuel as fuel and a storage unit for storing the biomass fuel, A method for burning biomass fuel, which includes a drying step of drying the biomass fuel using a heat medium gas containing at least one of the exhaust gas of the combustion device and the gas heated by heat exchange with the exhaust gas between the storage unit and the combustion device.

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