Wood fuel combustion system

Abstract

To provide a woody fuel combustion system capable of sufficiently drying woody fuel using gas having exchanged heat with steam in a condenser.SOLUTION: The woody fuel combustion system comprises: a boiler for combusting woody furl to generate steam; an air-cooled condenser for condensing steam generated in the boiler by exchanging heat with gas; a conveyance line for conveying dried gas having exchanged heat with steam in the air-cooled condenser; and a static dryer configured to allow the dried gas conveyed by the conveyance line to flow through deposits of the woody fuel standing still.SELECTED DRAWING: Figure 1

Description

Technical Field

[0001] The present disclosure relates to a wood fuel combustion system.

Background Art

[0002] Wood fuels such as wood chips may contain a large amount of moisture, and when burning wood fuels, it may be necessary to dry the wood fuels in advance. For example, Patent Document 1 discloses a technique for drying wood fuels conveyed by a belt conveyor with air (dry air) that has been heat-exchanged with steam by a condenser.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] However, since the dry air supplied from the condenser is at a low temperature (about 50 degrees), in the technique described in Patent Document 1, there is a risk that the wood fuel will be conveyed by the belt conveyor before it is sufficiently dried.

[0005] The present disclosure has been made in view of the above problems, and an object thereof is to provide a wood fuel combustion system capable of sufficiently drying wood fuel with a gas that has been heat-exchanged with steam by a condenser.

Means for Solving the Problems

[0006] To achieve the above objective, the wood fuel combustion system according to this disclosure comprises: a boiler that burns wood fuel to generate steam; an air-cooled condenser that condenses the steam generated in the boiler by heat exchange with gas; a transport line for transporting the dry gas, which is the gas that has undergone heat exchange with the steam in the air-cooled condenser; and a stationary drying device configured to pass the dry gas transported by the transport line through a deposit of wood fuel that is stationary. [Effects of the Invention]

[0007] According to the wood fuel combustion system disclosed herein, the wood fuel can be thoroughly dried with the gas that has been heat-exchanged with steam by the condenser. [Brief explanation of the drawing]

[0008] [Figure 1] This diagram schematically shows the configuration of the wood fuel combustion system according to the first embodiment. [Figure 2] This diagram schematically shows the configuration of an air-cooled condenser according to the first embodiment. [Figure 3] This diagram schematically shows the configuration of the transport line according to the first embodiment. [Figure 4] This figure schematically shows the configuration of a stationary drying apparatus according to the first embodiment. [Figure 5] This diagram schematically shows the configuration of an air-cooled condenser according to the second embodiment. [Figure 6] This is a diagram illustrating the configuration of a transport line according to the second embodiment. [Figure 7] This diagram schematically shows the configuration of a duct according to several embodiments. [Figure 8] This diagram schematically shows the configuration of an air-cooled condenser according to several embodiments. [Modes for carrying out the invention]

[0009] The wood fuel combustion system according to the embodiments of this disclosure will be described below with reference to the drawings. Such embodiments represent one aspect of this disclosure and are not limiting, and can be modified at will within the scope of the technical concept of this disclosure.

[0010] <First Embodiment> (composition) Figure 1 is a schematic diagram showing the configuration of a wood fuel combustion system 1 according to the first embodiment. As illustrated in Figure 1, the wood fuel combustion system 1 includes a boiler 2, an air-cooled condenser 4, a conveyor line 6, and a stationary drying device 8.

[0011] Boiler 2 burns wood fuel F to produce steam S. Boiler 2 is, for example, a fluidized bed boiler that directly burns wood fuel F to produce high-temperature, high-pressure steam S. Wood fuel F is, for example, wood chips. In the first embodiment, the wood fuel combustion system 1 further includes a steam turbine 10 that is rotationally driven by the steam S produced in boiler 2, and a generator 12 that converts the rotational energy of the steam turbine 10 into electrical energy.

[0012] The air-cooled condenser 4 condenses the steam S generated in the boiler 2 by heat exchange with gas G. In the first embodiment, as illustrated in Figure 1, the air-cooled condenser 4 condenses the steam S (hereinafter referred to as discharged steam S1) discharged from the steam turbine 10. The wood fuel combustion system 1 further includes a condensate tank 14 in which the condensate W discharged from the air-cooled condenser 4 is stored, and a condensate pump (not shown) sends the condensate W stored in the condensate tank 14 to the boiler 2, where steam S is regenerated from the condensate W. The boiler 2 may also be configured to be supplied with feedwater separately from the condensate W.

[0013] An example of the specific configuration of the air-cooled condenser 4 will be described. Figure 2 is a schematic diagram showing the configuration of the air-cooled condenser 4 according to the first embodiment. As illustrated in Figure 2, the air-cooled condenser 4 includes a header 20, one heat transfer surface 22, the other heat transfer surface 24, a manifold 26, and a blower 28.

[0014] Header 20 is a pipe to which the exhaust steam S1 from the steam turbine 10 is supplied, and the exhaust steam S1 flows through it. Header 20 extends linearly along one of the horizontal directions orthogonal to the vertical direction D1. In the present disclosure, as illustrated in FIG. 2, the direction orthogonal to the one direction in which Header 20 extends among the horizontal directions is defined as the left-right direction D2. In the left-right direction D2, a virtual line L1 that passes through the axis O of Header 20 in the vertical direction D1 is defined.

[0015] Each of the one-side heat transfer surface 22 and the other-side heat transfer surface 24 extends downward from Header 20 and is inclined with respect to the vertical direction D1. Each of the one-side heat transfer surface 22 and the other-side heat transfer surface 24 is configured to allow the exhaust steam S1 to flow through, and includes, for example, a plurality of heat transfer tubes (fin tubes). In the form illustrated in FIG. 2, the other-side heat transfer surface 24 is located on the opposite side of the one-side heat transfer surface 22 across the virtual line L1. The interval 23 between the one-side heat transfer surface 22 and the other-side heat transfer surface 24 increases as it goes downward from Header 20. The one-side heat transfer surface 22 is disposed on the left side of the left-right direction D2 with Header 20 at the center, and the other-side heat transfer surface 24 is disposed on the right side of the left-right direction D2 with Header 20 at the center. The other-side heat transfer surface 24 is arranged symmetrically with respect to the one-side heat transfer surface 22 around Header 20.

[0016] The header tank 26 is connected to the lower ends of each of the one-side heat transfer surface 22 and the other-side heat transfer surface 24, and the condensate W generated in each of the one-side heat transfer surface 22 and the other-side heat transfer surface 24 flows in, and this condensate W is discharged from the air-cooled condenser 4. As described above, the condensate W discharged from the air-cooled condenser 4 is stored in the condensate tank 14.

[0017] The blower 28 is disposed below both the one-side heat transfer surface 22 and the other-side heat transfer surface 24, and blows the gas G toward both the one-side heat transfer surface 22 and the other-side heat transfer surface 24. The blower 28 is located between the lower end of the one-side heat transfer surface 22 and the lower end of the other-side heat transfer surface 24 in the left-right direction D2. The gas G is, for example, air.

[0018] The air-cooled condenser 4 according to such a first embodiment performs condensate treatment by blowing the gas G from below onto the one-side heat transfer surface 22 and the other-side heat transfer surface 24. In the air-cooled condenser 4, a flow space 25 is formed through which each of the gas G that has passed through the one-side heat transfer surface 22 and the gas G that has passed through the other-side heat transfer surface 24 flows as the dry gas Gd(G). The flow space 25 is located on the downstream side of each of the one-side heat transfer surface 22 and the other-side heat transfer surface 24 in the flow direction in which the gas G flows through the air-cooled condenser 4. The flow space 25 is open to the atmosphere. In some embodiments, the temperature of the dry gas Gd is included in the range of 40 degrees or more and 60 degrees or less.

[0019] The transport line 6 transports the dry gas Gd, which is the gas G heat-exchanged with the vapor S in the air-cooled condenser 4. In the first embodiment, as illustrated in FIG. 1, one end 6a of the transport line 6 is connected to the air-cooled condenser 4, and the other end 6b is connected to the stationary drying device 8. The transport line 6 transports the dry gas Gd heat-exchanged with the discharged vapor S1 from the air-cooled condenser 4 to the stationary drying device 8. That is, the transport line 6 transports the dry gas Gd flowing through the flow space 25 from the air-cooled condenser 4 to the stationary drying device 8.

[0020] FIG. 3 is a diagram schematically showing the configuration of the transport line 6 according to the first embodiment. As illustrated in FIG. 3, the transport line 6 includes a duct 30 and a fan 32. The duct 30 communicates the stationary space 41, which will be described later, with the flow space 25. In the form illustrated in FIG. 3, the duct 30 includes an inlet 34 formed at one end 6a and opening into the flow space 25, and an outlet 36 formed at the other end 6b and opening into the stationary space 41. The fan 32 is provided in the duct 30 and is driven by a drive source not shown to extract a part of the dry gas Gd from the flow space 25 and transport it to the stationary space 41.

[0021] The stationary drying apparatus 8 is configured to pass the drying gas Gd, which has been transported by the transport line 6, through the pile Fm of woody fuel F that is being stored. In the first embodiment, the stationary drying apparatus 8 is configured to pass the drying gas Gd through the pile Fm of woody fuel F from bottom to top. Figure 4 is a schematic diagram showing the configuration of the stationary drying apparatus 8 according to the first embodiment. As illustrated in Figure 4, the stationary drying apparatus 8 includes a main body 40 in which a stationary space 41 is formed inside, and a stationary section 42 that is placed in the stationary space 41.

[0022] The main body 40 has a cylindrical shape, for example, a rectangular shape when viewed from above. The main body 40 has an inlet 44 formed below the stationary section 42 for the dry gas Gd conveyed by the conveyor line 6 to flow into the stationary space 41. In the embodiment illustrated in Figure 4, the inlet 44 is formed at the lower end of the main body 40. The main body 40 has an outlet 46 formed above the stationary section 42 for the dry gas Gd to flow out of the stationary space 41. In the embodiment illustrated in Figure 4, the outlet 46 is formed at the upper end of the main body 40.

[0023] The stationary section 42 is a mesh-like member with multiple holes extending along the vertical direction D1, or a structure in which drying gas discharge holes are made in the floor surface or a tube attached to the floor surface. The stationary section 42 has a sieve that can prevent the wood fuel F introduced into the stationary drying apparatus 8 from falling below the stationary section 42. Therefore, when wood fuel F is introduced into the stationary drying apparatus 8, the wood fuel F accumulates in the stationary section 42, and a deposit of wood fuel F Fm is formed in the stationary space 41. In other words, the stationary drying apparatus 8 is configured so that the deposit of wood fuel F Fm can be stationary in the stationary space 41, and the drying gas Gd passes through the stationary section 42 and then the deposit of wood fuel F Fm.

[0024] Let h1 be the maximum height of the wood fuel F deposit Fm, and let v be the flow velocity of the dry gas Gd passing through the wood fuel F deposit Fm (hereinafter referred to as the apparent flow velocity). In the first embodiment, 1.0 m

[0025] Although not shown, in some embodiments, the stationary drying apparatus 8 further includes a load cell that acquires the weight of the wood fuel F deposit Fm accumulated in the stationary space 41. Therefore, the drying state of the wood fuel F can be determined by monitoring the value of the load cell. Although not shown, in some embodiments, the stationary drying apparatus 8 further includes an inlet thermometer that acquires the temperature of the drying gas Gd flowing into the stationary space 41, and an outlet thermometer that acquires the temperature of the drying gas Gd flowing out of the stationary space 41. Therefore, the drying state of the wood fuel F can be determined by monitoring the difference between the value of the inlet thermometer and the value of the outlet thermometer. In some embodiments, the stationary drying apparatus 8 further includes an inlet thermometer and a deposit thermometer that measures the temperature of the deposit Fm instead of the outlet thermometer. While measuring the temperature of the dry gas Gd flowing out of the stationary space 41 may not be easy, measuring the temperature of the sediment Fm is easy, and the drying state of the woody fuel F can be obtained from the difference between the temperature of the dry gas Gd flowing into the stationary space 41 and the temperature of the sediment. Therefore, the drying state of the woody fuel F can also be determined by monitoring the difference between the value of the inflow thermometer and the value of the sediment thermometer. The stationary drying apparatus 8 may include a weighing scale, an inflow thermometer, an outflow thermometer, and a sediment thermometer.

[0026] ​Although not shown in the figures, in some embodiments, the stationary drying apparatus 8 further includes a flow meter that acquires the flow rate of the drying gas Gd flowing into the stationary space 41 (hereinafter referred to as the inflow flow rate). The apparent flow velocity v is the value obtained by dividing the flow rate of the drying gas Gd by the cross-sectional area of ​​the stationary space when the stationary space 41 is cut in a direction perpendicular to the vertical direction D1 (horizontal direction). Therefore, by monitoring the value of the flow meter (inflow flow rate), it is possible to determine whether the apparent flow velocity v is suitable for drying the woody fuel F.

[0027] (Effects / Actions) The operation and effects of the wood fuel combustion system 1 according to the first embodiment will now be described. According to the first embodiment, the stationary drying device 8 is configured so that the wood fuel F deposit Fm can be stationary in the stationary space 41, and the drying gas Gd can be passed through the wood fuel F deposit Fm until the wood fuel F deposit Fm is sufficiently dried. For this reason, the wood fuel F can be sufficiently dried with the relatively low temperature drying gas Gd which has been heat-exchanged with the exhaust steam S1 by the air-cooled condenser 4. Specifically, the wet-bulb temperature of the drying gas Gd is determined by the moisture content (which is the same as the absolute humidity of the atmosphere) contained in the drying gas Gd and the raised temperature, and drying to that range is possible in a relatively short time (within 5 hours). Therefore, drying is possible even if the drying gas temperature is not particularly high, such as 60°C or higher. For example, if air at an ambient temperature of 15°C and relative humidity of 60% is heated to 45°C in an air-cooled condenser and used as dry gas Gd, 1 kg of air has the capacity to dry 9 g of moisture from wood chips. By controlling the drying time, wood chips with a moisture content of 100% (wood containing the same amount of moisture as dry wood) can be dried to a moisture content of 50% or less within 5 hours, ensuring sufficient dry wood performance for combustion in boiler 2.

[0028] According to the first embodiment, the provision of a transport line 6 allows the stationary drying apparatus 8 to be installed at any desired location. Therefore, compared to Patent Document 1, maintenance of the stationary drying apparatus 8, loading of wood fuel F into the stationary drying apparatus 8, and removal of wood fuel F from the stationary drying apparatus 8 can be made easier.

[0029] According to the first embodiment, by passing the drying gas Gd through the wood fuel F deposit Fm from bottom to top, contact between the wood fuel F and the drying gas Gd is improved compared to when the drying gas Gd is passed through the wood fuel F deposit Fm in a different direction. This allows the moisture contained in the wood fuel F to move as water vapor along with the drying gas Gd to the top of the wood fuel F deposit Fm, thereby efficiently drying the wood fuel. However, this disclosure is not limited to the direction of passage of the drying gas Gd being from bottom to top. For example, the stationary drying apparatus 8 may be configured to pass the drying gas Gd through the wood fuel F deposit Fm from left to right.

[0030] The drying efficiency of wood fuel F can be improved by gradually increasing the apparent flow velocity v from 0 m / s. However, if the apparent flow velocity v increases further, the drying gas Gd will preferentially flow through the gaps formed between adjacent wood fuel Fs (so-called "through-flow" occurs), which may reduce the drying efficiency of the wood fuel F. According to the inventors' findings, the apparent flow velocity v for achieving good drying efficiency of wood fuel F is set based on the maximum value h1. Specifically, 1.0 m

[0031] Furthermore, this disclosure is not limited to the configuration of the air-cooled condenser 4 as illustrated in the first embodiment. The air-cooled condenser 4 can have any configuration as long as it condenses steam S generated in the boiler 2 by heat exchange with gas G.

[0032] ​For example, in some embodiments, the air-cooled condenser 4 includes either one of the one-side heat transfer surface 22 or the other-side heat transfer surface 24. In some embodiments, the air-cooled condenser 4 includes the one-side heat transfer surface 22, a one-side blower positioned below the one-side heat transfer surface 22 and blowing gas G toward the one-side heat transfer surface 22, the other-side heat transfer surface 24, and a other-side blower positioned separately from the one-side blower and below the other-side heat transfer surface 24, and blowing gas G toward the other-side heat transfer surface 24.

[0033] <Second Embodiment> A wood fuel combustion system 1 according to a second embodiment of this disclosure will now be described. In the second embodiment, the air-cooled condenser 4 is further provided with one side wall 50 and the other side wall 52. In the second embodiment, components that are the same as those of the first embodiment are denoted by the same reference numerals, and their detailed description is omitted.

[0034] (composition) Figure 5 is a schematic diagram showing the configuration of the air-cooled condenser 4 according to the second embodiment. Figure 6 is a diagram illustrating the configuration of the transport line 6 according to the second embodiment.

[0035] As illustrated in Figure 5, the air-cooled condenser 4 further includes one side wall 50 and the other side wall 52.

[0036] One side wall 50 is positioned downstream of the one heat transfer surface 22 in the gas flow direction of G. This one side wall 50 extends along the vertical direction D1 and forms a one downstream space 51 between it and the one heat transfer surface 22. The other side wall 52 is positioned downstream of the other heat transfer surface 24 in the gas flow direction of G. This other side wall 52 extends along the vertical direction D1 and forms a other downstream space 53 between it and the other heat transfer surface 24. The other side wall 52 is positioned symmetrically to the one side wall 50 with respect to the header 20. The one side wall 50 and the other side wall 52 are constructed similarly to each other, and the configuration of the one side wall 50 will be described in detail below, but the configuration of the other side wall 52 will be omitted.

[0037] In the embodiment illustrated in Figure 5, the air-cooled condenser 4 further includes a bottom plate 56 that connects the lower end of one side wall 50 to a manifold pipe 26 connected to the lower end of one heat transfer surface 22. The bottom plate 56 is integrally formed with the one side wall 50. The one downstream space 51 is defined by being enclosed by the one heat transfer surface 22, the one side wall 50, and the bottom plate 56. The one downstream space 51 opens upward. The bottom plate 56 also connects the lower end of the other side wall 52 to a manifold pipe 26 connected to the lower end of the other heat transfer surface 24.

[0038] Although not shown, in some embodiments, the air-cooled condenser 4 further includes a wall connecting one side wall 50 and the other side wall 52, and at least a portion of the heat transfer surface 22 on one side and at least a portion of the heat transfer surface 24 on the other side are arranged within the internal space defined by the one side wall 50, the other side wall 52, and the wall. In this case, the one side wall 50, the other side wall 52, and the wall may be integrally constructed.

[0039] In the second embodiment, as illustrated in Figure 6, the transport line 6 includes a duct 30 having a main body 60, a first extraction unit 62, and a second extraction unit 64, and a fan 32 positioned in the main body 60.

[0040] In the main body 60, the other end 6b of the aforementioned transport line 6 is formed at the downstream end 60b on the downstream side in the direction in which the dry gas Gd flows through the transport line 6, and the upstream end 60a on the upstream side is configured so that the dry gas Gd extracted from one downstream space 51 and the dry gas Gd extracted from the other downstream space 53 merge.

[0041] In the direction in which the dry gas Gd flows through the transport line 6, the first extraction section 62 has its downstream end 62b connected to the upstream end 60a of the main body 60, and its upstream end 62a forms one end 6a of the transport line 6. A first inlet 63 is formed at the upstream end 62a of the first extraction section 62, which opens into the one-sided downstream space 51.

[0042] The second extraction unit 64 has its downstream end 64b connected to the upstream end 60a of the main body 60 in the direction in which the dry gas Gd flows through the conveying line 6, and its upstream end 64a forms one end 6a of the conveying line 6. A second inlet 65 is formed at the upstream end 64a of the second extraction unit 64, opening to the other downstream space 53. The second inlet 65 is positioned symmetrically to the first inlet 63 with respect to the header 20. The first inlet 63 and the second inlet 65 are configured similarly to each other, and the configuration of the first inlet 63 will be described in detail below, but the configuration of the second inlet 65 will be omitted.

[0043] In the second embodiment, as illustrated in Figure 5, the first extraction section 62 penetrates one side wall 50, and the first inlet 63 is located within the one-side downstream space 51. Within the range D1 in the vertical direction where the first inlet 63 is located, if the distance from one side wall 50 to one-side heat transfer surface 22 is d, the first inlet 63 is located in a range of 0.6d or less. If the height of one side wall 50 is h2, the first inlet 63 is located in a range of 0.25h2 or more and 0.6h2 or less. The first inlet 63 opens downward and is inclined at an angle of 45 degrees or more with respect to the vertical direction D1 so that it moves away from the imaginary line L1 as it goes downward. In some embodiments, the first inlet 63 is inclined more significantly with respect to the vertical direction D1 than the one-side heat transfer surface 22.

[0044] In the second embodiment, as illustrated in Figure 5, the upper end surface of one side wall 50 is located below the header 20. The height h2 of one side wall 50 is more than half the length dL of the heat transfer surface 22 on one side.

[0045] (Effects / Actions) The operation and effects of the wood fuel combustion system 1 according to the second embodiment will now be described. According to the second embodiment, by simply adding relatively inexpensive equipment such as a side wall 50, a duct 30, and a fan 32, the wood fuel F can be sufficiently dried with a relatively low-temperature dry gas Gd that has been heat-exchanged with the exhaust steam S1 by the air-cooled condenser 4.

[0046] According to the second embodiment, since the first inlet 63 is located in a range of 0.6d or less, it is possible to secure dry gas Gd while suppressing turbulence of the dry gas Gd in the one-sided downstream space 51 by the duct 30.

[0047] In the second embodiment, the first extraction section 62 penetrates one side wall 50 and the first inlet 63 is located within the one downstream space 51, but the disclosure is not limited to this form. Figure 7 is a schematic diagram showing the configuration of a duct 30 according to several embodiments. As illustrated in Figure 7, the duct 30 has one end 66 connected to the one side wall 50, which includes the first inlet 63 that opens into the one downstream space 51. The duct 30 also includes a diameter-reducing section 70 that decreases in diameter from one end 66 toward the other end 68 of the duct 30.

[0048] In the embodiment illustrated in Figure 7, one end 66 of the duct 30 is enclosed by the wall surface 59 of the one side wall 50 on the heat transfer surface 22 side. That is, the first inlet 63 faces horizontally to the one downstream space 51. In some embodiments, one end 66 of the duct 30 is located on the opposite side from the one downstream space 51 to the wall surface 59 of the one side wall 50. In the embodiment illustrated in Figure 7, the reduced diameter section 70 has a curved shape such that the inner diameter changes smoothly from one end 66 to the other end 68. In some embodiments, the reduced diameter section 79 has a straight shape such that the amount of change in the inner diameter is approximately the same from one end 66 to the other end 68.

[0049] If the first inlet 63 is located above 0.6h2, air is drawn in from above, the temperature of the extracted dry gas Gd decreases, and the drying efficiency of the wood fuel F may decrease. On the other hand, if the first inlet 63 is located below 0.25h2, air descending along one side wall 50 is drawn in, the temperature of the extracted dry gas Gd decreases, and the drying efficiency of the wood fuel F may decrease. According to the second embodiment, since the first inlet 63 is located in the range of 0.25h2 to 0.6h2, it is possible to secure dry gas Gd with a temperature that is sufficient to dry the wood fuel F.

[0050] The dry gas Gd that has passed through the heat transfer surface 22 on one side flows upward through the downstream space 51 on one side (see Figure 5). Therefore, according to the second embodiment, by opening the first inlet 63 downward and tilting it at an angle of 45 degrees or more with respect to the vertical direction D1, it becomes easier to allow the dry gas Gd to flow into the first extraction section 62.

[0051] If the height h2 of one side wall 50 is less than half the length dL of the heat transfer surface 22 on one side, the amount of air flowing into the downstream space 51 on one side increases, the temperature of the dry gas Gd circulating in the downstream space 51 on one side decreases, and the drying efficiency of the wood fuel F may decrease. According to the second embodiment, the height h2 of one side wall 50 is more than half the length dL of the heat transfer surface 22 on one side, so that a dry gas Gd having a temperature sufficient to dry the wood fuel F can be secured.

[0052] In the second embodiment, the wall surface 59 of the one side wall 50 on the heat transfer surface 22 side extended in the vertical direction D1, but the disclosure is not limited to this embodiment. Figure 8 is a schematic diagram showing the configuration of an air-cooled condenser 4 according to several embodiments. In some embodiments, as illustrated in Figure 8, the wall surface 59 of the one side wall 50 on the heat transfer surface 22 side is inclined with respect to the vertical direction D1 so as it moves downward, it moves away from the imaginary line L1. With such a configuration, by extending the one side wall 50 along the inclination of the heat transfer surface 22, turbulence of the dry gas Gd in the one downstream space 51 can be suppressed.

[0053] According to the second embodiment, the duct 30 extracts dry gas Gd from both the downstream space 51 on one side and the downstream space 53 on the other side, so that the impact on the operation of the air-cooled condenser 4 can be suppressed compared to the case where extraction is performed from either the downstream space 51 on one side or the downstream space 53 on the other side. In the second embodiment, the duct 30 had one first extraction section 62 and one second extraction section 64, but the disclosure is not limited to this form. The duct 30 may have a plurality of first extraction sections 62. The duct 30 may have a plurality of second extraction sections 64.

[0054] According to the second embodiment, since the second inlet 65 is located symmetrically with respect to the first inlet 63 with respect to the header 20, the impact on the operation of the air-cooled condenser 4 can be further suppressed.

[0055] The contents described in each of the above embodiments can be understood, for example, as follows:

[0056] [1] The wood fuel combustion system (1) relating to this disclosure is A boiler (2) that burns wood fuel (F) to produce steam (S), (4) an air-cooled condenser that condenses the steam generated in the boiler by heat exchange with gas (G), A transport line (6) for transporting the dry gas (Gd), which is the gas that has undergone heat exchange with the steam in the air-cooled condenser, The system includes a stationary drying apparatus (8) configured to pass the drying gas conveyed by the conveying line through the stationary pile of wood fuel (Fm).

[0057] According to the configuration described in [1] above, the wood fuel deposit is placed in a stationary drying apparatus, allowing the drying gas to pass through the wood fuel deposit until it is sufficiently dry. Therefore, the wood fuel can be thoroughly dried with the gas (drying gas) that has been heat-exchanged with steam by the air-cooled condenser. In addition, the presence of a conveyor line allows the stationary drying apparatus to be installed at any desired location.

[0058] [2] In some embodiments, in the configuration described in [1] above, The static drying apparatus is configured to allow the drying gas to pass from below to above the pile of wood fuel.

[0059] According to the configuration described in [2] above, by passing the dry gas from bottom to top through the pile of wood fuel, contact between each piece of wood fuel contained in the pile and the dry gas is made relatively good, and the moisture contained in each piece of wood fuel is moved as water vapor along with the dry gas to the top of the pile of wood fuel, thereby efficiently drying each piece of wood fuel.

[0060] [3] In some embodiments, in the configuration described in [2] above, Let h1 be the maximum height of the wood fuel deposit, and let v be the flow velocity of the dry gas passing through the wood fuel deposit. 1.0m It satisfies the condition.

[0061] The drying efficiency of wood fuel can be improved by gradually increasing the flow velocity v from 0 m / s. However, if the flow velocity v increases further, the drying gas will preferentially flow through the gaps formed between adjacent wood fuels (so-called "through-flow" occurs), which may reduce the drying efficiency of the wood fuel. According to the inventors' findings, the flow velocity v required to achieve good wood fuel drying efficiency is set based on the maximum value h1. Specifically, 1.0 m

[0062] [4] In some embodiments, in the configuration described in any one of [1] to [3] above, The aforementioned air-cooled condenser is, The header (20) to which the steam is supplied, A heat transfer surface (22) extending downward from the header, inclined with respect to the vertical direction (D1), and through which the steam can flow, A blower (28) positioned below the one-side heat transfer surface and blowing the gas toward the one-side heat transfer surface, ​​A side wall positioned downstream of the one heat transfer surface in the gas flow direction, comprising a one side wall (50) that extends along the vertical direction and forms a one downstream space (51) between itself and the one heat transfer surface, The aforementioned transport line is A duct (30) connects the stationary space (41) in the stationary drying apparatus where the wood fuel deposits are placed to the downstream space on one side, The system includes a fan (32) provided inside the duct.

[0063] According to the configuration described in [4] above, wood fuel can be sufficiently dried with the gas (dry gas) that has been heat-exchanged with steam by the condenser, by simply adding relatively inexpensive equipment such as a side wall, ducts, and a fan.

[0064] [5] In some embodiments, in the configuration described in [4] above, If the distance from the one side wall to the one side heat transfer surface is d, then the first inlet (63) opening into the one side downstream space of the duct is located in a range of 0.6d or less.

[0065] If the first inlet is located in a range greater than 0.6, the turbulence of the dry gas in the one-sided downstream space due to the duct is large. According to the configuration described in [5] above, it is possible to secure dry gas while suppressing the turbulence of the dry gas in the one-sided downstream space.

[0066] [6] In some embodiments, in the configuration described in [4] or [5] above, If the height of the aforementioned one side wall is h2, the first inlet opening into the downstream space on the one side of the duct is located in the range of 0.25h2 to 0.6h2.

[0067] If the first inlet is located above 0.6h2, air is drawn in from above, lowering the temperature of the dry gas and potentially reducing the drying efficiency of the wood fuel. On the other hand, if the first inlet is located below 0.25h2, air descending along one side wall is drawn in, lowering the temperature and potentially reducing the drying efficiency of the wood fuel. The configuration described in [6] above ensures that the dry gas has a temperature sufficient to adequately dry the wood fuel.

[0068] [7] In some embodiments, in the configuration described in any one of [4] to [6] above, The duct is connected at one end to the one side wall, The duct includes a reduced diameter section that decreases in diameter from one end towards the other end of the duct.

[0069] According to the configuration described in [7] above, the duct will open horizontally to the downstream space on one side. In this case, the amount of dry gas flowing into the duct can be increased by providing a diameter reduction section.

[0070] [8] In some embodiments, in the configuration described in any one of [4] to [7] above, The first inlet, which opens into the downstream space on one side of the duct, opens downward and is inclined at an angle of 45 degrees or more with respect to the vertical direction so that it moves away from the imaginary line (L1) passing through the header in the vertical direction as it extends downward.

[0071] The dry gas that has passed through the heat transfer surface on one side may flow upward through the downstream space on one side, at an angle to the imaginary line. For this reason, according to the configuration described in [8] above, it becomes easy to open the first inlet of the duct perpendicular or nearly perpendicular to the direction of flow of the dry gas and allow the dry gas to flow into the duct.

[0072] [9] In some embodiments, in the configuration described in any one of [4] to [8] above, The height (h2) of the aforementioned one side wall is more than half the length of the aforementioned one side heat transfer surface.

[0073] If the height of one side wall is less than half the length of the heat transfer surface on one side, the amount of air flowing into the downstream space on one side increases, the temperature of the dry gas circulating in the downstream space on one side decreases, and the drying efficiency of the wood fuel may decrease. According to the configuration described in [9] above, it is possible to secure a dry gas that has a temperature sufficient to dry the wood fuel.

[0074]

[10] In some embodiments, in the configuration described in any one of [4] to [9] above, The wall surface (59) of the one side wall on the heat transfer surface side is inclined with respect to the vertical direction so that it moves away from the imaginary line passing through the header in the vertical direction as it extends downward.

[0075] According to the configuration described in

[10] above, by extending one side wall along the slope of the heat transfer surface on one side, turbulence of the dry gas in the downstream space on one side can be suppressed.

[0076]

[11] In some embodiments, in the configuration described in any one of [4] to

[10] above, The aforementioned air-cooled condenser is, The other heat transfer surface (24) extends downward from the header, is inclined with respect to the vertical direction, and is through which the steam can flow, and is located in the left-right direction (D2) on the opposite side from the one heat transfer surface, with a virtual line passing through the header in the vertical direction. The other side wall is located downstream of the other heat transfer surface in the gas flow direction, and further includes the other side wall (52) which extends along the vertical direction and forms a downstream space (53) between itself and the other heat transfer surface, The aforementioned duct is, A first extraction section (62) is formed which has a first inlet that opens into the downstream space on one side, It has a second extraction section (64) in which a second inlet (65) is formed that opens to the other downstream space.

[0077] According to the configuration described in

[11] above, the duct extracts dry gas from both the downstream space on one side and the downstream space on the other side, thus suppressing the impact on the operation of the air-cooled condenser compared to the case where the gas is extracted from either the downstream space on one side or the downstream space on the other side.

[0078]

[12] In some embodiments, in the configuration described in

[11] above, The other heat transfer surface is arranged symmetrically with respect to the one heat transfer surface with respect to the header. The second entrance is positioned symmetrically with respect to the first entrance, with respect to the header.

[0079] The configuration described in

[12] above can further reduce the impact on the operation of the air-cooled condenser. [Explanation of Symbols]

[0080] 1. Wood fuel combustion system 2 Boilers 4. Air-cooled condenser 6 Conveyor Line 8 Stationary dryer 20 Header 22 One-sided heat transfer surface 24 Other side heat transfer surface 25 Distribution space 26 Collecting pipe 28 Blower 30 ducts 32 Fans 41 Still space 50 One side wall 51 Downstream space on one side 52 Other side wall 53 Downstream space on other side 59 One side wall surface 62 First extraction section 63 Entrance 1 64 Second extraction section 65 Second Entrance D1 Vertical direction D2 Left / right direction F wood fuel Fm sediments G Gas Gd dry gas L1 virtual line S Steam

Claims

1. A boiler that burns wood fuel to generate steam, An air-cooled condenser that condenses the steam generated in the boiler by heat exchange with gas, A conveying line for transporting the dry gas, which is the gas that has undergone heat exchange with the steam in the air-cooled condenser, The system includes a stationary drying apparatus configured to pass the drying gas conveyed by the conveying line through the stationary pile of wood fuel, The aforementioned air-cooled condenser is, The header to which the steam is supplied, A heat transfer surface on one side extends downward from the header, is inclined in the vertical direction, and through which the steam can flow, A blower positioned below the one-side heat transfer surface and blowing the gas toward the one-side heat transfer surface, A side wall positioned downstream of the one heat transfer surface in the gas flow direction, comprising a side wall that extends along the vertical direction and forms a one-side downstream space between itself and the one heat transfer surface, The aforementioned transport line is A duct connecting the stationary space where the wood fuel deposits are placed in the stationary drying apparatus and the downstream space on one side, A fan provided within the duct, Wood fuel combustion system.

2. The static drying apparatus is configured to allow the drying gas to pass from below to above the pile of wood fuel. The wood fuel combustion system according to claim 1.

3. Let h1 be the maximum height of the wood fuel deposit, and let v be the flow velocity of the dry gas passing through the wood fuel deposit. 1.0 m < h1 < 3.0 m, and 0.1 m / s < v < 0.6 m / s Satisfying The wood fuel combustion system according to claim 2.

4. If the distance from the one side wall to the one side heat transfer surface is d, then the first inlet opening into the one side downstream space of the duct is located in a range of 0.6d or less. A wood fuel combustion system according to any one of claims 1 to 3.

5. If the height of the aforementioned one side wall is h2, then the first inlet opening into the downstream space on the one side of the duct is located in the range of 0.25h2 to 0.6h2. The wood fuel combustion system according to claim 4.

6. The duct is connected at one end to the one side wall, The duct includes a diameter-reducing section that decreases in diameter from one end towards the other end of the duct. A wood fuel combustion system according to any one of claims 1 to 3.

7. The first inlet, which opens into the downstream space on one side of the duct, opens downward and is inclined at an angle of 45 degrees or more with respect to the vertical direction so that it moves away from the imaginary line passing through the header in the vertical direction as it extends downward. A wood fuel combustion system according to any one of claims 1 to 3.

8. The height of the aforementioned one side wall is more than half the length of the aforementioned one side heat transfer surface. A wood fuel combustion system according to any one of claims 1 to 3.

9. The wall surface of the one side wall on the heat transfer surface side is inclined with respect to the vertical direction so that it moves away from the imaginary line passing through the header in the vertical direction as it extends downward. A wood fuel combustion system according to any one of claims 1 to 3.

10. The aforementioned air-cooled condenser is, A heat transfer surface on the other side that extends downward from the header, is inclined with respect to the vertical direction, and through which the steam can flow, the heat transfer surface on the other side that is located on the opposite side from the heat transfer surface on the left-right side, with a virtual line passing through the header in the vertical direction, The other side wall is located downstream of the other heat transfer surface in the gas flow direction, and further includes the other side wall extending along the vertical direction, forming a downstream space between itself and the other heat transfer surface. The aforementioned duct is, A first extraction section is formed in which a first inlet is formed that opens into the downstream space on one side, It has a second extraction section in which a second inlet is formed that opens to the other downstream space, A wood fuel combustion system according to any one of claims 1 to 3.

11. The other heat transfer surface is arranged symmetrically with respect to the one heat transfer surface with respect to the header. The second inlet is positioned symmetrically with respect to the first inlet with respect to the header. The wood fuel combustion system according to claim 10.

Images