JP7371795B2 - Boiler system and how to operate the boiler system - Google Patents

Description

The present disclosure relates to a boiler system and a method of operating a boiler system. This application claims the benefit of priority based on Japanese Patent Application No. 2021-91171 filed on May 31, 2021, the contents of which are incorporated into this application.

In recent years, in order to prevent global warming, there has been a need to reduce CO ₂ (carbon dioxide) emissions. For this reason, in a boiler, a technique for burning biomass in addition to coal, and a technique for burning biomass instead of coal (for example, Patent Document 1) are being considered.

JP 2021-1701 Publication

However, depending on the type of biomass, the melting point of biomass combustion ash produced by combustion may be low, and the biomass combustion ash may melt and adhere to the inner wall of the boiler. In this case, there was a problem in that the heat exchange efficiency of the boiler decreased.

In view of such problems, the present disclosure aims to provide a boiler system that can increase the melting point of combustion ash, and a method of operating the boiler system.

In order to solve the above problems, a boiler system according to one aspect of the present disclosure includes a first fuel storage section that stores biomass as a solid fuel, and a second fuel storage section that stores coal as a solid fuel. an additive supply section that supplies an additive containing at least silica and alumina to the secondary air supply port of the furnace, and a concentration of calcium contained in the combustion ash after combustion is 30% by mass or less. a fuel supply unit that supplies solid fuel to the furnace from each of the plurality of fuel storage units , and the first fuel storage unit stores either or both of woody biomass and herbaceous biomass. It has a first biomass storage section and a second biomass storage section that stores waste biomass containing either one or both of empty palm bunches and palm shells.
The fuel supply unit may also include an additive storage section that stores additives, and the fuel supply section may supply the additives to the furnace in addition to the solid fuel.
The fuel supply unit also includes a bunker that mixes the solid fuel supplied from each of the plurality of fuel storage units and the additive supplied from the additive storage unit, and a bunker that pulverizes the solid fuel and additive mixed by the bunker. However, it may also have a mill that supplies the furnace.

The fuel supply unit also supplies solid fuel to the furnace from each of the plurality of fuel storage units and solid fuel from the additive storage unit to the furnace so that the concentration of silica and alumina contained in the combustion ash is 40% by mass or more. The amount of additive may be controlled.

Further, a dust removal device is provided that collects combustion ash from the combustion exhaust gas exhausted from the furnace, and the additive may be the combustion ash recovered by the dust removal device.

It also includes a heat exchanger that exchanges heat between the flue gas exhausted from the furnace and water, and a cleaning section that cleans the combustion ash with the water heat exchanged by the heat exchanger. It may be combustion ash after being washed.
Moreover, the heat exchanger may be provided between the furnace and the dust removal device.
Further, the fuel supply unit may control the amount of solid fuel supplied to the furnace from each of the plurality of fuel storage units so that the concentration of sulfur contained in the entire solid fuel supplied to the furnace is 20 mmol/kg or more. good.
Further, the additive may be combustion ash of either or both of coal and biomass.

In order to solve the above problems, another boiler system according to one aspect of the present disclosure includes a dust removal device that collects combustion ash from combustion exhaust gas exhausted from the furnace, and a dust removal device that collects combustion ash from the combustion exhaust gas exhausted from the furnace, and heats the combustion exhaust gas exhausted from the furnace and water. A heat exchanger that exchanges heat, a washing section that washes combustion ash with the water heat exchanged by the heat exchanger, and an addition that supplies the combustion ash washed by the washing section to the secondary air supply port of the furnace. and a fuel supply section that supplies biomass to the furnace, and the biomass includes one or both of woody biomass and herbaceous biomass, as well as empty palm fruit bunches and palm shells. It is a waste biomass containing one or both of the following .

In order to solve the above problems, a method for operating a boiler system according to one aspect of the present disclosure includes: a first biomass storage section that stores either or both of woody biomass and herbaceous biomass as solid fuel; a second biomass storage section that stores waste biomass containing either one or both of empty palm bunches and palm shells as a solid fuel; and a first fuel storage section that has coal as the solid fuel. A method for operating a boiler system equipped with a plurality of fuel storage parts including a second fuel storage part for storing Solid fuel is supplied to the furnace from each of the plurality of fuel storage parts so that the concentration of calcium contained in the subsequent combustion ash is 30% by mass or less.

According to the present disclosure, it is possible to increase the melting point of combustion ash.

FIG. 1 is a diagram illustrating a boiler system according to this embodiment. FIG. 2 is a diagram illustrating the fuel supply unit according to this embodiment. FIG. 3 is a flowchart illustrating the process flow of the boiler system operating method according to the present embodiment. FIG. 4 is a diagram illustrating the relationship between aluminosilicate and chloride ions contained in combustion ash. FIG. 5 is a diagram illustrating the relationship between sulfur and chloride ions contained in the entire solid fuel. FIG. 6 is a diagram illustrating the relationship between calcium and chloride ions contained in combustion ash.

Embodiments of the present disclosure will be described in detail below with reference to the accompanying drawings. The dimensions, materials, specific numerical values, etc. shown in such embodiments are merely examples for easy understanding, and do not limit the present disclosure unless otherwise specified. In this specification and drawings, elements having substantially the same functions and configurations are designated by the same reference numerals to omit redundant explanation, and elements not directly related to the present disclosure are omitted from illustration. do.

[Boiler system 100]
FIG. 1 is a diagram illustrating a boiler system 100 according to this embodiment. Note that in FIG. 1, solid arrows indicate the flow of solid fuel, combustion ash, and water. In FIG. 1, dashed arrows indicate air flow.

As shown in FIG. 1, the boiler system 100 includes a fuel supply unit 110, a furnace 112, a forced fan 114, a denitrification device 120, an air preheater 122, a dust removal device 124, an induction fan 126, and a recirculation fan 126. It includes a heater 128, a desulfurization device 130, a boost-up fan 132, a pump 140, a heat exchanger 142, a cleaning section 144, and a drying section 146.

Fuel supply unit 110 supplies solid fuel and additives to furnace 112 . The fuel supply unit 110 will be detailed later.

The air supply flow path 10 is connected to the furnace 112 . A forced fan 114 is provided in the air supply flow path 10 . The air supplied by the forced fan 114 is preheated by an air preheater 122, which will be described later, and is guided to the furnace 112 through the air supply channel 10. The furnace 112 burns the solid fuel supplied by the fuel supply unit 110 with air. The furnace 112 is, for example, a pulverized coal boiler (PC boiler) or a circulating fluidized bed boiler (CFB boiler). The combustion exhaust gas generated in the furnace 112 passes through the flue 20 and is emitted into the atmosphere from the chimney 30.

The combustion exhaust gas generated by burning the solid fuel in the furnace 112 contains nitrogen oxides (NOx), sulfur oxides (SOx), combustion ash, mercury, and halogen. Therefore, the flue 20 connecting the furnace 112 and the chimney 30 includes a denitrification device 120, an air preheater 122, a dust removal device 124, an induction fan 126, a reheater 128, a desulfurization device 130, and a boost-up fan 132. provided.

The induction fan 126 and the boost-up fan 132 guide the combustion exhaust gas generated in the furnace 112 to the chimney 30.

The denitrification device 120 includes a denitrification catalyst. The denitrification device 120 reduces nitrogen oxides contained in the combustion exhaust gas.

Air preheater 122 is provided downstream of denitrification device 120 in flue 20 . The air preheater 122 exchanges heat between the combustion exhaust gas from which nitrogen oxides have been removed by the denitrification device 120 and the air passing through the air supply flow path 10 . That is, the air preheater 122 heats the air supplied by the forced fan 114 using the heat contained in the combustion exhaust gas.

The dust removal device 124 is provided downstream of the air preheater 122 in the flue 20 . The dust removal device 124 is, for example, an electric dust collector or a bag filter. The dust removal device 124 collects combustion ash from the combustion exhaust gas.

The induced fan 126 is provided downstream of the dust removal device 124 in the flue 20 . Reheater 128 is provided downstream of induced fan 126 in flue 20 . The reheater 128 exchanges heat between the combustion exhaust gas flowing between the induction fan 126 and the desulfurizer 130 and the combustion exhaust gas flowing between the boost-up fan 132 and the chimney 30.

Desulfurization device 130 is provided downstream of induction fan 126 in flue 20 . Sulfur oxides and hydrogen chloride (HCl) contained in combustion exhaust gas are removed by dissolving them in an aqueous solution. The boost-up fan 132 is provided downstream of the desulfurization device 130 in the flue 20.

Pump 140 supplies water to heat exchanger 142. Heat exchanger 142 is provided between air preheater 122 and dust removal device 124 in flue 20 . Heat exchanger 142 is an indirect heat exchanger. The heat exchanger 142 exchanges heat between the water supplied by the pump 140 and the combustion exhaust gas flowing through the flue 20 . That is, the heat exchanger 142 heats water using the heat contained in the combustion exhaust gas. The heat exchanger 142 heats water to, for example, 70° C. or more and less than 100° C. (approximately 80° C.).

Combustion ash collected by the dust removal device 124 and water heated by the heat exchanger 142 are guided to the cleaning section 144 . The cleaning section 144 cleans the combustion ash with water heated by the heat exchanger 142. The cleaned combustion ash is led to a drying section 146.

Furthermore, the water after washing contains potassium and phosphorus. Therefore, the water after washing may be used as fertilizer after being subjected to a predetermined treatment.

The drying section 146 exchanges heat between the combustion ash cleaned by the cleaning section 144 and the air flowing through the air supply flow path 10 . Drying section 146 is an indirect heat exchanger. The combustion ash is dried by heat exchange between the combustion ash and the air in the drying section 146. The combustion ash after heat exchange is guided to the fuel supply unit 110. Moreover, the air after heat exchange is guided to the air supply flow path 10.

[Fuel supply unit 110]
Next, the fuel supply unit 110 will be explained. FIG. 2 is a diagram illustrating the fuel supply unit 110 according to this embodiment. As shown in FIG. 2, the fuel supply unit 110 includes a first fuel storage section 210, a second fuel storage section 212, an additive storage section 214, and a fuel supply section 220.

The first fuel storage section 210 (fuel storage section) stores biomass (solid fuel). The biomass is one or more of woody biomass, herbaceous biomass, and waste biomass. Woody biomass is, for example, wood, sawdust, bark, etc. In addition, examples of herbaceous (plant) biomass include sugarcane, sorghum, bamboo, wheat straw, and rice straw. Examples of waste biomass include Empty Fruit Bunch (EFB) and Palm Kernel Shell (PKS), which are produced as a result of producing palm oil from palm trees. Note that the first fuel storage section 210 may store biomass pellets. Pellet is made by processing solid fuel (biomass) into a cylindrical shape of several millimeters to several centimeters.

The second fuel storage section 212 (fuel storage section) stores coal (solid fuel). The coal is any one or more of anthracite, semi-anthracite, bituminous coal, sub-bituminous coal, and lignite.

The additive storage section 214 stores additives. The additive includes at least silica (SiO ₂ ) and alumina (Al ₂ O ₃ ). For example, the additive includes aluminosilicate (SiO ₂ .Al ₂ O ₃ ). In this embodiment, the additive storage section 214 stores the combustion ash that has been cleaned by the cleaning section 144 and dried by the drying section 146 as an additive.

The fuel supply unit 220 supplies additives to the furnace 112 in addition to biomass and coal. In this embodiment, the fuel supply section 220 includes a first supply pipe 230, a second supply pipe 232, a third supply pipe 234, a first valve 240, a second valve 242, a third valve 244, It includes a bunker 250, a mill 252, and a fuel control section 260.

The first supply pipe 230 is a pipe that communicates the first fuel storage section 210 and the bunker 250. The second supply pipe 232 is a pipe that communicates the second fuel storage section 212 and the bunker 250. The third supply pipe 234 is a pipe that communicates the additive storage section 214 and the bunker 250.

The first valve 240 is provided in the first supply pipe 230 . The first valve 240 changes the opening degree of the flow path formed in the first supply pipe 230. In this embodiment, the first fuel storage section 210 is located above the bunker 250. Therefore, when the first valve 240 is opened, the biomass stored in the first fuel storage section 210 is supplied to the bunker 250 by its own weight.

The second valve 242 is provided in the second supply pipe 232. The second valve 242 changes the opening degree of the flow path formed in the second supply pipe 232. Similar to the first fuel storage section 210, the second fuel storage section 212 is located above the bunker 250 in this embodiment. Therefore, when the second valve 242 is opened, the coal stored in the second fuel storage section 212 is supplied to the bunker 250 by its own weight.

The third valve 244 is provided in the third supply pipe 234. The third valve 244 changes the opening degree of the flow path formed in the third supply pipe 234. Similar to the first fuel reservoir 210 and the second fuel reservoir 212, the additive reservoir 214 is located above the bunker 250 in this embodiment. Therefore, when the third valve 244 is opened, the additive stored in the additive storage section 214 is supplied to the bunker 250 by its own weight.

The first valve 240, the second valve 242, and the third valve 244 are, for example, rotary valves.

Bunker 250 mixes biomass, coal, and additives. Mill 252 grinds the biomass, coal, and additives mixed by bunker 250. The biomass, coal, and additives pulverized by mill 252 are fed to the combustion port of furnace 112.

The fuel control section 260 is composed of a semiconductor integrated circuit including a CPU (central processing unit). The fuel control unit 260 reads programs, parameters, etc. for operating the CPU from the ROM. The fuel control unit 260 manages and controls the entire fuel supply unit 220 in cooperation with the RAM as a work area and other electronic circuits. In this embodiment, the fuel control unit 260 adjusts the opening degree of the first valve 240, the second valve 242, and the third valve 244.

Specifically, the fuel control unit 260 controls the mixture of solid fuel and additives supplied from the mill 252 to the furnace 112 to satisfy the following conditions (A), (B), and (C). Then, the opening degree of the first valve 240, the opening degree of the second valve 242, and the opening degree of the third valve 244 are adjusted.
Condition (A) Condition where the concentration of silica and alumina contained in the combustion ash (combustion ash after combustion) generated by combustion in the furnace 112 is 40% by mass (wt%) or more (B) Solid supplied to the furnace 112 Conditions where the concentration of sulfur (S) contained in the entire fuel (biomass and coal) is 20 mmol/kg or more (C) The concentration of calcium (Ca) contained in the combustion ash after combustion is 30% by mass or less

Note that coal has less calcium than biomass. Coal is also high in silica and alumina compared to biomass. Additionally, coal is high in sulfur compared to biomass. Also, as mentioned above, additives include silica and alumina.

Furthermore, the solid fuel (biomass) stored in the first fuel storage section 210, the solid fuel (coal) stored in the second fuel storage section 212, and the additive stored in the additive storage section 214 each contain The amounts of silica, alumina, sulfur, and calcium contained per unit volume are measured in advance using a predetermined device. The predetermined device is an inductively coupled plasma (ICP) mass spectrometry (ICP-MASS) device, an ICP optical emission spectrometry (ICP-AES) device, or an atomic absorption spectrometry (AAS) device.

[How to operate the boiler system]
Next, a method of operating the boiler system 100 will be explained. FIG. 3 is a flowchart illustrating the process flow of the operating method of the boiler system 100 according to the present embodiment. As shown in FIG. 3, the method of operating the boiler system 100 includes a fuel adjustment step S110 and a supply step S120.

[Fuel adjustment step S110]
The fuel control unit 260 controls the first valve 240 so that the mixture of solid fuel and additives supplied from the mill 252 to the furnace 112 satisfies the above conditions (A), (B), and (C). , the opening degree of the second valve 242, and the opening degree of the third valve 244.

Biomass, coal, and additives are then supplied to bunker 250. Bunker 250 mixes biomass, coal, and additives. The biomass, coal, and additives mixed by the bunker 250 satisfy all of the above conditions (A), (B), and (C).

The mixture produced by bunker 250 is then directed to mill 252.

[Supply process S120]
Mill 252 feeds the mixture produced by bunker 250 to furnace 112 .

As explained above, the boiler system 100 and the operating method of the boiler system 100 according to the present embodiment are such that the mixture of solid fuel and additives is fed into the furnace 111 so as to satisfy the above conditions (A) and (C). supply to. Thereby, the boiler system 100 can raise the melting point of the combustion ash produced in the furnace 112. Therefore, the boiler system 100 can suppress adhesion of combustion ash to the inner wall of the furnace 112. In other words, the boiler system 100 can promote the removal of combustion ash attached to the inner wall of the furnace 112. Therefore, the boiler system 100 can suppress a decrease in heat exchange efficiency.

In addition, the boiler system 100 and the method of operating the boiler system 100 according to the present embodiment are such that the mixture of solid fuel and additive is fed into the furnace so as to satisfy the above conditions (A), (B), and (C). 112. Thereby, the following reaction formulas (1) and (2) can proceed in the gas phase of the furnace 112.
Al ₂ O 3.2SiO ₂ +2KCl+ _{H 2} O → K ₂ O.Al ₂ O 3.2SiO ₂ +2HCl... _Reaction formula (1)
2KCl+ _SO2 +(1/ _{2O2 )} + _H2O → _K2O4 +2HCl...Reaction formula (2)
Therefore, the boiler system 100 can change alkali chloride (KCl), which causes corrosion of the inner walls and piping of the furnace 112, into hydrogen chloride (HCl). Thereby, the boiler system 100 can suppress corrosion of the inner wall of the furnace 112 and the piping. Note that, as described above, the hydrogen chloride generated as reaction formula (1) and reaction formula (2) proceed is removed by the desulfurization device 130.

Further, as described above, the boiler system 100 mixes the solid fuel and the additive in the bunker 250 so as to satisfy the above conditions (A), (B), and (C). As a result, the boiler system 100 can suppress the adhesion of combustion ash to the inner wall of the furnace 112 and the corrosion caused by the combustion ash, compared to the comparative example in which solid fuel and additives are supplied to the furnace 112 through separate ports. Specifically, in the comparative example, the locations where silica, alumina, and sulfur flow may be limited depending on the flow condition inside the furnace 112, and it is difficult to reduce the fixation of combustion ash and corrosion caused by combustion ash. There will be a bias in the areas where it is possible. In contrast, boiler system 100 can supply solid fuel and additives to furnace 112 in a substantially uniformly mixed state. Thereby, the boiler system 100 can flow silica, alumina, and sulfur evenly into the furnace 112, and can suppress the adhesion of combustion ash to the inner wall of the furnace 112 and the corrosion caused by the combustion ash. Become.

Further, the boiler system 100 supplies the mixture of solid fuel and additive to the furnace 112 so as to satisfy the above conditions (A) and (C). Thereby, the boiler system 100 is able to suppress the adhesion of combustion ash to the inner wall of the furnace 112 and the corrosion caused by the combustion ash, regardless of the nature of the biomass, such as the type of biomass and the place of production.

Further, the boiler system 100 supplies the mixture of solid fuel and additive to the furnace 112 so as to satisfy the above condition (A). That is, the boiler system 100 adjusts the concentrations of silica and alumina contained in the combustion ash. The amount of combustion ash per unit volume varies depending on the type of solid fuel. Therefore, compared to the comparative example in which the concentrations of silica and alumina contained in the solid fuel are adjusted, the boiler system 100 can avoid a situation where silica and alumina are excessively contained in the combustion ash.

Further, as described above, the boiler system 100 supplies biomass to the furnace 112 as solid fuel. Therefore, the boiler system 100 can reduce _CO2 emissions compared to the case where only coal is supplied to the furnace 112.

Further, as described above, the boiler system 100 uses the combustion ash collected by the dust removal device 124 as an additive. Thereby, the boiler system 100 can reduce the cost required for additives.

Furthermore, conventionally, the combustion ash collected by the dust removal device 124 has been landfilled. In contrast, the boiler system 100 uses at least a portion of the combustion ash collected by the dust removal device 124 as an additive. Therefore, the boiler system 100 can reduce the cost required for burying combustion ash.

Moreover, since the boiler system 100 uses at least a portion of the combustion ash collected by the dust removal device 124 as an additive, the properties of the combustion ash can be stabilized. Therefore, the boiler system 100 can use the combustion ash collected by the dust removal device 124 and not used as an additive as a raw material for concrete or fertilizer.

The boiler system 100 also includes a cleaning section 144. Thereby, alkali metals and alkaline earth metals can be removed from the combustion ash collected by the dust removal device 124. Therefore, by using the cleaned combustion ash as an additive, the boiler system 100 can avoid a situation where the melting point of the combustion ash decreases .

[Example]
The solid fuel was burned in a combustion furnace equipped with a simulated water tube with a metal temperature controlled at 650°C. Then, the concentration of chloride ions (Cl ⁻ ) contained in the combustion ash attached to the simulated water pipe was measured.

FIG. 4 is a diagram illustrating the relationship between aluminosilicate and chloride ions contained in combustion ash. In FIG. 4, the horizontal axis indicates the concentration [wt%] of aluminosilicate contained in the combustion ash. In FIG. 4, the vertical axis indicates the concentration of chloride ions [mmol/kg] contained in the combustion ash.

As shown in FIG. 4, as the amount of aluminosilicate contained in the combustion ash increases, the concentration of chloride ions contained in the combustion ash decreases. Further, in a range where the amount of aluminosilicate is more than 0 wt% and less than 40 wt%, the concentration of chloride ions decreases rapidly as the amount of aluminosilicate increases. On the other hand, when the amount of aluminosilicate is in the range from 40 wt% to 75 wt%, the concentration of chloride ions decreases slowly as the amount of aluminosilicate increases.

From the above results, the boiler system 100 can efficiently reduce the concentration of chloride ions by setting the concentration of silica and alumina contained in the combustion ash after combustion to 40 wt% or more and 100 wt% or less. It was confirmed that this can be reduced.

FIG. 5 is a diagram illustrating the relationship between sulfur and chloride ions contained in the entire solid fuel. In FIG. 5, the horizontal axis indicates the concentration of sulfur [mmol/kg] contained in the entire solid fuel. In FIG. 5, the vertical axis indicates the concentration [mmol/kg] of chloride ions contained in the combustion ash.

As shown in FIG. 5, as the amount of sulfur contained in the entire solid fuel increases, the concentration of chloride ions contained in the combustion ash decreases. Further, in a range where the amount of sulfur is more than 0 mmol/kg and less than 20 mmol/kg, the concentration of chloride ions decreases rapidly as the amount of sulfur increases. On the other hand, when the amount of sulfur is in the range from 20 mmol/kg to 60 mmol/kg, the decrease in the concentration of chloride ions as the amount of sulfur increases is gradual.

Based on the above results, the boiler system 100 can control the concentration of chloride ions by setting the concentration of sulfur contained in the entire solid fuel to 20 mmol/kg or more and 781 mmol/kg (2.5 wt%). It was confirmed that this can be effectively reduced.

FIG. 6 is a diagram illustrating the relationship between calcium and chloride ions contained in combustion ash. In FIG. 6, the horizontal axis indicates the concentration [wt%] of calcium (CaO, which is an oxide equivalent value of calcium) contained in the combustion ash. In FIG. 6, the vertical axis indicates the concentration [mmol/kg] of chloride ions contained in the combustion ash.

As shown in FIG. 6, in a range where the amount of calcium contained in the combustion ash is more than 0 wt% and 50 wt% or less, as the amount of calcium increases, the concentration of chloride ions contained in the combustion ash increases. Further, in a range where the amount of calcium is more than 0 wt% and less than 20 wt%, when the amount of calcium increases, the concentration of chloride ions slightly increases. In a range where the amount of calcium is more than 20 wt% and less than 30 wt%, the concentration of chloride ions increases rapidly as the amount of calcium increases. Further, in a range where the amount of calcium is more than 30 wt% and less than 35 wt%, the concentration of chloride ions increases rapidly as the amount of calcium increases. In a range where the amount of calcium is more than 35 wt% and less than 40 wt%, as the amount of calcium increases, the concentration of chloride ions slightly increases. In a range where the amount of calcium is more than 40 wt% and less than 50 wt%, the concentration of chloride ions increases slowly as the amount of calcium increases.

On the other hand, in a range where the amount of calcium is more than 50 wt% and less than 65 wt%, as the amount of calcium increases, the concentration of chloride ions slightly decreases.

From the above results, the boiler system 100 can efficiently reduce the concentration of chloride ions by setting the concentration of calcium contained in the combustion ash after combustion to more than 0 wt% and 30 wt% or less. was confirmed.

Although the embodiments have been described above with reference to the accompanying drawings, it goes without saying that the present disclosure is not limited to the above embodiments. It is clear that those skilled in the art can come up with various changes and modifications within the scope of the claims, and it is understood that these naturally fall within the technical scope of the present disclosure. be done.

For example, in the embodiment described above, the boiler system 100 is exemplified as having a configuration including two fuel storage sections (the first fuel storage section 210 and the second fuel storage section 212). However, the boiler system 100 may include three or more fuel reservoirs. Moreover, the case where the boiler system 100 is provided with the 1st fuel storage part 210 which stores biomass, and the 2nd fuel storage part 212 which stores coal was mentioned as an example. However, the boiler system 100 only needs to include a plurality of fuel storage sections each storing different types of solid fuel selected from a plurality of types of biomass. Alternatively, the boiler system 100 may include a plurality of fuel storage sections each storing different types of solid fuel selected from one or more types of biomass and one or more types of coal. Note that the fuel storage section preferably stores solid fuel that has been previously cut into a predetermined size or coarsely pulverized.

For example, it may include a fuel storage section that stores either woody biomass (including bark and rice husks) or herbaceous biomass washed with water, and a fuel storage section that stores waste biomass. It's okay. Woody biomass (including bark and rice husks) and herbaceous biomass washed with water contain more silica, alumina, and sulfur than waste biomass.

Further, in the above embodiment, the boiler system 100 includes the additive storage section 214 as an example. However, the boiler system 100 may not include the additive storage section 214.

Further, in the above embodiment, the boiler system 100 is exemplified as having a configuration including the cleaning section 144. However, the boiler system 100 may not include the cleaning section 144. In this case, the combustion ash collected by the dust removal device 124 is used as it is as an additive. In this case, the boiler system 100 can reduce the cost required for additives. Moreover, the boiler system 100 can reduce the cost required for burying combustion ash. Furthermore, the boiler system 100 can stabilize the properties of combustion ash.

Further, in the above embodiment, an example is given in which the boiler system 100 uses combustion ash collected by the dust removal device 124 as an additive. However, the additive only needs to contain at least silica and alumina. For example, the additive may be combustion ash of coal and/or biomass, or kaolinite.

In addition, when using coal combustion ash (coal ash) as an additive, you may use the coal ash deposited at the bottom of a furnace among the coal ash produced in other coal-fired boiler systems. By using the coal ash deposited at the bottom of the furnace, it is possible to suppress the mixing of heavy metals and trace components into the combustion ash produced in the boiler system 100. Examples of heavy metals include mercury (Hg), selenium (Se), arsenic (As), cadmium (Cd), and lead (Pb). Trace components are fluorine (F), boron (B), and iodine (I).

Furthermore, when biomass combustion ash (biomass ash) is used as an additive, biomass ash that has been washed with water may be used. Thereby, it is possible to avoid a situation where the melting point of the combustion ash produced in the boiler system 100 decreases.

Further, in the above embodiment, the case where a plurality of types of solid fuels and additives are mixed in the bunker 250 has been exemplified. However, each of the plurality of types of solid fuels and additives may be independently supplied to the furnace 112. For example, multiple types of solid fuels may be supplied to bunker 250 and additives may be supplied between mill 252 and furnace 112. Further, the plurality of types of solid fuels may be supplied to the bunker 250, and the additive may be supplied from the secondary air supply port of the furnace 112.

Further, in the above embodiment, when the fuel supply section 220 supplies the mixture of solid fuel and additive to the furnace 112 so as to satisfy all of the above conditions (A), (B), and (C), was given as an example. However, the fuel supply unit 220 only needs to supply the mixture of solid fuel and additive to the furnace 112 so as to satisfy at least condition (C). Thereby, the fuel supply unit 220 can increase the melting point of the combustion ash.

Further, in the above embodiment, an example is given in which the fuel control unit 260 simultaneously controls the opening degrees of the first valve 240, the second valve 242, and the third valve 244. However, the fuel control unit 260 may exclusively control the opening degrees of the first valve 240, the second valve 242, and the third valve 244. For example, the first valve 240, the second valve 242, and the third valve 244 are configured with on-off valves, and the fuel control unit 260 controls whether the solid fuel and additives in the bunker 250 are under the above conditions (A) or under the conditions (A). The first valve 240, the second valve 242, and the third valve 244 may be exclusively controlled to open and close so as to satisfy conditions (B) and (C).

Further, in the above embodiment, the boiler system 100 provides a fuel supply that supplies the mixture of solid fuel and additive to the furnace 112 so as to satisfy all of the above conditions (A), (B), and (C). The case where the section 220 is provided is taken as an example. However, instead of the fuel supply section 220, the boiler system may include a fuel supply section that supplies biomass and the combustion ash that has been cleaned by the cleaning section 144 to the furnace 112. That is, the boiler system includes a dust removal device 124 that collects combustion ash from the flue gas exhausted from the furnace 112, a heat exchanger 142 that exchanges heat between the flue gas exhausted from the furnace 112 and water, and a heat exchanger 142. It may also include a cleaning section 144 that cleans the combustion ash with water heat-exchanged by the cleaning section 144, and a fuel supply section that supplies the combustion ash washed by the cleaning section 144 and biomass to the furnace 112. Thereby, the boiler system can reduce the cost required for additives. Moreover, the boiler system can reduce the cost required for burying combustion ash. Furthermore, the boiler system can stabilize the properties of combustion ash.

This disclosure applies, for example, to Sustainable Development Goals (SDGs) Goal 7 “Ensure access to affordable, reliable, sustainable and modern energy” and Goal 13 “To combat climate change and its impacts.” can contribute to "taking emergency measures."

100: Boiler system 112: Furnace 124: Dust removal device 142: Heat exchanger 144: Cleaning section 210: First fuel storage section (fuel storage section) 212: Second fuel storage section (fuel storage section) 214: Additive storage section 220: Fuel supply section

Claims (11)

A plurality of fuel storage sections including a first fuel storage section that stores biomass as a solid fuel and a second fuel storage section that stores coal as a solid fuel;
an additive supply unit that supplies an additive containing at least silica and alumina to a secondary air supply port of the furnace;
a fuel supply unit that supplies the solid fuel from each of the plurality of fuel storage units to the furnace so that the concentration of calcium contained in the combustion ash after combustion is 30% by mass or less;
Equipped with
The first fuel storage section is
a first biomass storage section that stores either or both of woody biomass and herbaceous biomass;
a second biomass storage section that stores waste biomass containing one or both of empty palm bunches and palm shells;
A boiler system with comprising an additive storage section that stores the additive,
The boiler system according to claim 1, wherein the fuel supply unit supplies the additive to the furnace in addition to the solid fuel. The fuel supply section includes:
a bunker that mixes the solid fuel supplied from each of the plurality of fuel reservoirs and the additive supplied from the additive reservoir;
a mill that pulverizes the solid fuel and the additive mixed by the bunker and supplies it to the furnace;
The boiler system according to claim 2, comprising: The fuel supply unit supplies the solid fuel from each of the plurality of fuel storage units and the additive storage unit to the furnace so that the concentration of silica and alumina contained in the combustion ash is 40% by mass or more. The boiler system according to claim 2 or 3, wherein the amount of the additive supplied to the furnace is controlled. comprising a dust removal device that collects combustion ash from the combustion exhaust gas exhausted from the furnace,
The boiler system according to claim 4, wherein the additive is combustion ash collected by the dust removal device. a heat exchanger that exchanges heat between the combustion exhaust gas exhausted from the furnace and water;
a cleaning section that cleans the combustion ash with water heat exchanged by the heat exchanger;
Equipped with
The boiler system according to claim 5, wherein the additive is the combustion ash after being cleaned by the cleaning section. The boiler system according to claim 6, wherein the heat exchanger is provided between the furnace and the dust removal device. The fuel supply unit controls the amount of the solid fuel supplied to the furnace from each of the plurality of fuel storage units so that the concentration of sulfur contained in the entire solid fuel supplied to the furnace is 20 mmol/kg or more. The boiler system according to claim 1, wherein the boiler system controls: The boiler system according to claim 2, wherein the additive is combustion ash of one or both of coal and biomass. a dust removal device that collects combustion ash from combustion exhaust gas exhausted from the furnace;
a heat exchanger that exchanges heat between the combustion exhaust gas exhausted from the furnace and water;
a cleaning section that cleans the combustion ash with water heat exchanged by the heat exchanger;
an additive supply unit that supplies the combustion ash after being cleaned by the cleaning unit to a secondary air supply port of the furnace;
a fuel supply unit that supplies biomass to the furnace;
Equipped with
The biomass is
A boiler system that is a waste biomass containing one or both of woody biomass and herbaceous biomass, and one or both of empty palm bunches and palm shells. A first biomass storage section that stores one or both of woody biomass and herbaceous biomass as solid fuel, and waste containing one or both of empty palm bunches and palm shells. A boiler system comprising a plurality of fuel storage parts, including a second biomass storage part that stores system biomass as a solid fuel, a first fuel storage part that has a second biomass storage part that stores coal as a solid fuel, and a second fuel storage part that stores coal as a solid fuel. A driving method,
supplying an additive containing at least silica and alumina to a secondary air supply port of the furnace;
A method for operating a boiler system, comprising supplying the solid fuel from each of the plurality of fuel storage parts to the furnace so that the concentration of calcium contained in the combustion ash after combustion is 30% by mass or less.

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