Combustion gas cooling system

Abstract

To provide a combustion gas cooling device enabling a catalyst part to exhibit intended performance without increasing manufacturing cost.SOLUTION: An NOx removal device 100 includes: a mixing duct 10 having an inflow part 10a to which combustion gas flows in and an outflow part 10b from which the combustion gas flowing in from the inflow part 10a flows out; a cooling duct 40 for causing cooling gas having a temperature lower than that of the combustion gas to flow out into the mixing duct 10 and generating mixed gas obtained by mixing the combustion gas and the cooling gas; and an expanded duct 20 having an inflow part 20a that is connected to the mixing duct 10 and to which the mixed gas flows in and an outflow part 20b from which the mixed gas flowing in from the inflow part 20a flows out. The mixing duct 10 has a shape in which cross sectional areas at respective positions from the inflow part 10a toward the outflow part 20b are equal, and the expanded duct 20 has a shape in which a cross sectional area gradually increases from the inflow part 20a toward the outflow part 20b.SELECTED DRAWING: Figure 1

Description

Technical Field

[0001] The present disclosure relates to a combustion gas cooling device.

Background Art

[0002] Conventionally, a denitration device that decomposes nitrogen oxides contained in combustion gas discharged from a combustion engine such as a gas turbine to prevent adverse effects on the atmospheric environment is known. Further, it is known that when combustion gas exceeding the allowable temperature flows into a denitration device provided with a catalyst section for decomposing nitrogen oxides, the performance of the denitration device deteriorates or the denitration device malfunctions. In order to prevent such problems, a denitration device provided with a cooling device for cooling combustion gas on the upstream side of the catalyst section is known (see, for example, Patent Document 1 and Patent Document 2).

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Patent Document 2

Summary of the Invention

Problems to be Solved by the Invention

[0004] In the denitration devices disclosed in Patent Document 1 and Patent Document 2, the mixing duct for mixing cooling gas into the combustion gas has a shape in which the cross-sectional area gradually increases from the upstream side to the downstream side in the flow direction of the combustion gas. However, since the combustion gas flowing into the mixing duct flows linearly along the flow direction, it is difficult for the combustion gas to spread near the end in the width direction (the direction perpendicular to the flow direction) of the mixing duct whose cross-sectional area gradually increases. Therefore, the temperature near the end in the width direction of the mixing duct is lower than that in the central portion of the mixing duct, resulting in a bias in the temperature distribution in the width direction.

[0005] The mixed gas, a mixture of combustion gas and cooling gas, is guided to the catalyst section via an expanding duct. However, for the catalyst section to perform as desired, the maximum temperature of the mixed gas guided to the catalyst section must be within the catalyst section's optimal temperature range. The greater the bias in the temperature distribution in the width direction, the higher the maximum temperature of the mixed gas becomes, requiring a larger flow rate of cooling gas to lower the combustion gas temperature to within the catalyst section's optimal temperature range. Increasing the cooling gas flow rate requires increasing the number of cooling gas supply fans or installing high-performance fans, which increases the manufacturing cost of the denitrification system.

[0006] This disclosure is made in view of these circumstances and aims to provide a combustion gas cooling device that enables the catalyst to perform as desired without increasing manufacturing costs. [Means for solving the problem]

[0007] A combustion gas cooling device according to one aspect of the present disclosure comprises: a first duct having a first inlet into which combustion gas flows and a first outlet out which the combustion gas flowing in from the first inlet flows out; a cooling duct that discharges a cooling gas at a lower temperature than the combustion gas into the first duct to generate a mixed gas of the combustion gas and the cooling gas; and a second duct connected to the first duct and having a second inlet into which the mixed gas flows and a second outlet out which the mixed gas flowing in from the second inlet flows out, wherein the first duct has a shape in which the cross-sectional area is equal at each position from the first inlet to the first outlet, and the second duct has a shape in which the cross-sectional area gradually increases from the second inlet to the second outlet. [Effects of the Invention]

[0008] According to this disclosure, it is possible to provide a combustion gas cooling device that enables the catalyst to perform as desired without increasing manufacturing costs. [Brief explanation of the drawing]

[0009] [Figure 1]A perspective view showing a denitrification apparatus according to one embodiment of this disclosure. [Figure 2] This is a plan view from above of a denitrification apparatus according to one embodiment of the present disclosure. [Figure 3] This is a side view of a denitrification apparatus as seen from the side, according to one embodiment of the present disclosure. [Figure 4] This is a front view of the cooling duct as seen from the direction of arrow A in Figure 2. [Figure 5] Figure 4 is a cross-sectional view of the cooling duct taken along the arrow BB. [Figure 6] Figure 4 shows a cross-sectional view of the cooling duct taken along the CC arrow. [Figure 7] Figure 4 is a cross-sectional view of the cooling duct taken along the DD arrow. [Figure 8] Figure 4 shows a cross-sectional view of the cooling duct taken along the EE line. [Figure 9] Figure 5 is a partially enlarged view of the cooling gas flow path that constitutes the cooling duct shown. [Figure 10] Figure 7 is a partially enlarged view of the cooling gas flow path that constitutes the cooling duct shown. [Figure 11] Figure 9 is a perspective view of the cooling gas flow path. [Modes for carrying out the invention]

[0010] Hereinafter, a denitrification apparatus (combustion gas cooling apparatus) 100 according to one embodiment of the present disclosure will be described with reference to the drawings. Figure 1 is a perspective view showing the denitrification apparatus 100 according to this embodiment. Figure 2 is a plan view of the denitrification apparatus 100 according to this embodiment, viewed from above. Figure 3 is a side view of the denitrification apparatus 100 according to this embodiment, viewed from the side. The arrows shown in Figures 1-3 indicate the flow direction of the gas (combustion gas, mixed gas).

[0011] As shown in Figure 1, the denitrification apparatus 100 of this embodiment is a device that, for example, allows combustion gas (exhaust gas) at a high temperature of 550°C or higher, generated by combustion in a gas turbine (not shown), to flow in through an inlet duct 1, mixes the combustion gas and cooling gas in a mixing duct 10 to generate a mixed gas, and flows the mixed gas that has passed through an expansion duct 20 into a catalyst section 30.

[0012] As shown in FIGS. 1 to 3, the denitration device 100 includes an inlet duct 1, a mixing duct (first duct) 10, an expansion duct (second duct) 20, a catalyst section 30, and a cooling duct 40.

[0013] The inlet duct 1 is formed of a metal material such as iron or a heat-resistant material and functions as a flow path for the combustion gas. The inlet duct 1 includes an inlet portion 1a into which the combustion gas discharged from the gas turbine flows and an outlet portion 1b through which the combustion gas flowing into the inlet portion 1a flows out. The inlet portion 1a has a substantially circular cross-sectional shape in a direction orthogonal to the flow direction FD of the combustion gas.

[0014] On the other hand, the outlet portion 1b has a rectangular cross-sectional shape in a direction orthogonal to the flow direction FD of the combustion gas. The inlet duct 1 has a shape in which the cross-sectional area in a direction orthogonal to the flow direction FD of the combustion gas gradually increases from the inlet portion 1a toward the outlet portion 1b. For example, the flow velocity of the combustion gas discharged from the gas turbine in the inlet duct 1 is from 50 m / s to 100 m / s.

[0015] The mixing duct 10 is formed of a metal material such as iron or a heat-resistant material and functions as a flow path for the mixed gas in which the combustion gas and the cooling gas are mixed. The mixing duct 10 has an inlet portion (first inlet portion) 10a into which the combustion gas discharged from the outlet portion 1b of the inlet duct 1 flows and an outlet portion (first outlet portion) 10b through which the combustion gas flowing into the inlet portion 10a flows out.

[0016] The inlet portion 10a and the outlet portion 10b have a rectangular cross-sectional shape in a direction orthogonal to the flow direction FD of the combustion gas. The inlet portion 10a of the mixing duct 10 has the same shape as the outlet portion 1b of the inlet duct 1 and is connected so that no leakage of the combustion gas occurs. Note that the cross-sectional shapes of the inlet portion 10a and the outlet portion 10b are not limited to rectangular shapes, and may be elliptical, circular, or the like.

[0017] As shown in FIG. 2, in the mixing duct 10, the length in the width direction WD orthogonal to the flow direction FD of the combustion gas is constant at W1 from the inflow portion 10a to the outflow portion 10b. Further, as shown in FIG. 3, in the mixing duct 10, the length in the height direction HD orthogonal to the flow direction FD of the combustion gas is constant at H1 from the inflow portion 10a to the outflow portion 10b. Therefore, the mixing duct 10 has a shape in which the cross-sectional areas at each position from the inflow portion 10a to the outflow portion 10b are equal.

[0018] Note that the mixing duct 10 has a shape in which the length in the width direction WD is constant at W1 and the length in the height direction HD is constant at H1. However, any other shape may be used as long as the cross-sectional areas at each position from the inflow portion 10a to the outflow portion 10b are substantially equal. For example, a shape in which the length in the height direction HD is constant at H1 and the length in the width direction WD slightly increases from the inflow portion 10a to the outflow portion 10b may be used. As shown by the dotted line in FIG. 2, for example, a shape in which both ends in the width direction WD expand at an angle θw with respect to the flow direction FD of the combustion gas may be used. Here, the angle θw is set to an angle greater than 0° and less than 8°.

[0019] The expansion duct 20 is formed of a metal material such as iron or a heat-resistant material and functions as a flow path for the mixed gas in which the combustion gas and the cooling gas are mixed. The expansion duct 20 has an inflow portion (second inflow portion) 20a into which the combustion gas discharged from the outflow portion 10b of the mixing duct 10 flows, and an outflow portion (second outflow portion) 20b from which the combustion gas flowing into the inflow portion 20a flows out.

[0020] The cross-sectional shape of the inflow portion 20a in a direction substantially orthogonal to the flow direction FD of the combustion gas is rectangular. The cross-sectional shape of the outflow portion 20b in a direction substantially orthogonal to the flow direction FD of the combustion gas is a vertically long rectangle. The inflow portion 20a of the expansion duct 20 has the same shape as the outflow portion 10b of the mixing duct 10 and is connected so that no leakage of the mixed gas occurs. Note that the cross-sectional shapes of the inflow portion 20a and the outflow portion 20b are not limited to square or rectangular shapes, and may be elliptical or circular shapes, etc.

[0021] As shown in Figure 2, the length of the expansion duct 20 in the width direction WD perpendicular to the combustion gas flow direction FD is from the inlet 20a to the outlet 2 The shape is such that it gradually increases from W1 to W2 with a constant gradient up to 0b. Also, as shown in Figure 3, expansion duct 2 The shape of 0 is such that the length of the height HD perpendicular to the combustion gas flow direction FD gradually increases from H1 to H2 at a constant gradient from the inlet 20a to the outlet 20b. Therefore, the expanding duct 20 has a shape in which the cross-sectional area gradually expands at a constant gradient from the inlet 20a to the outlet 20b.

[0022] As shown in Figure 2 , burn In the flow direction FD of the combustion gas, the mixing duct 10 has a length L1, and the expanding duct 20 has a length L2. It is desirable to set lengths L1 and L2 so as to satisfy the following equation (1). 0.5 ≤ L1 / L2 ≤ 1.5 (1)

[0023] The catalyst unit 30 decomposes nitrogen oxides contained in the mixed gas and discharges the decomposed mixed gas to the outside (atmosphere) of the denitrification device 100. The expansion duct 20 is equipped with an injection unit (not shown) that injects a reducing agent into the expansion duct 20 to cause a reduction reaction of the mixed gas passing through the catalyst unit 30. The injection unit has, for example, a cylindrical flow path with multiple holes, and ammonia passing through this flow path is injected into the expansion duct 20 through the multiple holes. Although ammonia is a typical example of a reducing agent, other types of reducing agents can also be used. The mixed gas into which the reducing agent has been injected by the injection unit then flows into the catalyst unit 30 via the outlet 20b of the expansion duct 20.

[0024] The catalyst section 30 functions as a denitrification device that decomposes nitrogen oxides contained in the combustion gas into water and nitrogen, which are injected with a reducing agent by the injection section. In the first embodiment, a selective catalytic reduction (SCR) method is used to decompose nitrogen oxides using ammonia as a reducing agent.

[0025] The catalyst section 30, like the mixing duct 10 and the expansion duct 20, is made of a metal material such as iron or a heat-resistant material and functions as a flow path for the mixed gas, which is a mixture of combustion gas and cooling gas. What distinguishes it from the mixing duct 10 and the expansion duct 20 is that multiple catalyst packs (not shown) are arranged in the flow path. The catalyst pack is a catalyst component filled with a catalyst that reacts the mixed gas with ammonia to decompose nitrogen oxides (nitric oxide, nitrogen dioxide, etc.) in the exhaust gas into water and nitrogen. The catalyst pack is composed of a grid-like or plate-like catalyst so that the mixed gas can flow through its interior. The catalyst's main component is TiO2, with active components such as vanadium and tungsten added.

[0026] The temperature at which the catalyst promotes the reaction in which the mixed gas is decomposed into nitrogen and water is preferably between 300°C and 500°C, and more preferably between 300°C and 470°C. Below 300°C, the activity of the catalyst decreases, and a larger amount of catalyst is required to improve the denitrification performance. On the other hand, above 470°C, ammonia (NH3) is oxidized, and consequently, the amount of ammonia (NH3) decreases, leading to a problem of reduced denitrification performance. Furthermore, above 500°C, not only is it not a suitable temperature for the reduction reaction, but it also exceeds the heat resistance temperature of the catalyst itself, potentially damaging the catalyst. Therefore, the temperature of the mixed gas supplied to the catalyst is preferably 500°C or lower, and more preferably between 300°C and 470°C.

[0027] The cooling duct 40 is made of a metal material such as iron or a heat-resistant material, and allows a cooling gas at a lower temperature than the combustion gas to flow into the mixing duct 10, thereby generating a mixed gas of combustion gas and cooling gas. In this embodiment, for example, four cooling ducts (40a, 40b, 40c, and 40d in order from bottom to top) are arranged at intervals in the height direction of the mixing duct 10.

[0028] In this embodiment, the mixing ducts 10 are spaced apart in the height direction, but this is not limited to this configuration. For example, they may be spaced apart in the width direction of the mixing ducts 10, or arranged in a direction intersecting the combustion gas flow direction FD. Various gases at a lower temperature than the combustion gas can be used as the cooling gas, but in this embodiment, atmospheric air is used as the cooling gas. In the following description, the four cooling ducts will be denoted by reference numeral 40 when described without distinction, and by reference numeral 40a, 40b, 40c, or 40d when described separately.

[0029] As shown in Figure 2, the cooling duct 40 is equipped with two cooling gas inlets 41a and 41b that are substantially perpendicular to the combustion gas flow direction FD, and cooling gas flows in from the two cooling gas inlets 41a and 41b. Each of the two cooling gas inlets is connected to a connecting duct (not shown) which has an air fan (not shown) inside the flow path. The air fan uses the power of a motor or the like to draw air from the atmosphere into the connecting duct, and guides the air that functions as cooling gas through the connecting duct to the cooling gas inlets 41a and 41b.

[0030] Figure 4 is a front view of the cooling duct 40 as seen from the direction of arrow A in Figure 2. As shown in Figure 4, the four cooling ducts 40a, 40b, 40c, and 40d are arranged at regular intervals along the height direction HD of the mixing duct 10. Each cooling duct 40 is fixed to the side wall surface of the mixing duct 10 with bolts or the like. Note that it is not necessary for the four cooling ducts 40a, 40b, 40c, and 40d to be arranged at regular intervals in the height direction; their intervals may be varied.

[0031] Each cooling duct 40 is provided with multiple cooling gas outlet holes 60 at different positions along the longitudinal direction of the cooling duct 40 (the width direction WD of the mixing duct 10). Regarding the cooling duct 40a, it is provided with 16 cooling gas outlet holes, numbered 60a to 60p, at different positions along the longitudinal direction of the cooling duct 40a. As shown in Figure 4, the cooling gas outlet holes (openings) 60 have a length L3 along the width direction WD.

[0032] Of the 16 cooling gas outlets, eight of them (the first cooling gas outlets), 60b, 60d, 60f, 60h, 60i, 60k, 60m, and 60o, open downwards in the height direction HD of the mixing duct 10. On the other hand, eight of the cooling gas outlets (the second cooling gas outlets), 60a, 60c, 60e, 60g, 60j, 60l, 60n, and 60p, open upwards in the height direction HD.

[0033] As shown by the arrows in Figure 4, cooling gas flows out downwards in the height direction HD from the cooling gas outlets 60b, 60d, 60f, 60h, 60i, 60k, 60m, and 60o of the mixing duct 10, which are opened downwards in the height direction HD. On the other hand, cooling gas flows out upwards in the height direction HD from the cooling gas outlets 60a, 60c, 60e, 60g, 60j, 60l, 60n, and 60p of the mixing duct 10, which are opened upwards in the height direction HD.

[0034] The multiple cooling gas outlets 60a to 60p include cooling gas outlets that open in different directions. Furthermore, the cooling gas outlets that open downward in the vertical direction (the height direction of the mixing duct 10) and the cooling gas outlets that open upward in the height direction HD of the mixing duct 10 are arranged alternately along the width direction WD which is perpendicular to the combustion gas flow direction FD.

[0035] By arranging multiple cooling gas outlets 60a to 60p alternately along the width direction WD, mixing of the cooling gas and combustion gas is promoted, and the temperature distribution of the mixed gas supplied to the catalyst section 30 in the width direction WD can be made uniform. Note that the number of cooling gas outlets opening upward in the height direction HD of the mixing duct 10 is not limited to eight, nor is the number of cooling gas outlets opening downward in the height direction HD of the mixing duct 10 limited to eight.

[0036] Figure 5 is a cross-sectional view of the cooling duct 40 shown in Figure 4, taken along the arrow BB. Figure 6 is a cross-sectional view of the cooling duct 40 shown in Figure 4, taken along the arrow CC. Figure 7 is a cross-sectional view of the cooling duct 40 shown in Figure 4, taken along the arrow DD. Figure 8 is a cross-sectional view of the cooling duct 40 shown in Figure 4, taken along the arrow EE. As shown in Figures 5 to 7, the cooling duct 40 is a duct formed by multiple circular pipes that extend along the width direction WD and have a circular cross-section perpendicular to the width direction WD.

[0037] As shown in Figure 5, cooling gas flows out of the cooling gas outlet 60p, which is opened upwards in the height direction HD of the mixing duct 10, diagonally upwards in the height direction HD. This outflowing cooling gas has both a velocity component directed upwards in the height direction HD and a velocity component directed in the combustion gas flow direction FD.

[0038] Furthermore, as shown in Figure 7, cooling gas flows out of the cooling gas outlet 60o, which is opened downwards in the height direction HD of the mixing duct 10, diagonally downwards in the height direction HD. This outflowing cooling gas has both a velocity component directed downwards in the height direction HD and a velocity component directed in the combustion gas flow direction FD.

[0039] As shown in Figure 6, a partition plate 61a is placed between the cooling gas outlet 60p, which opens upward in the height direction HD of the mixing duct 10, and the cooling gas outlet 60o, which opens downward in the height direction HD. This partition plate separates the flow so that the cooling gases flowing out from adjacent cooling gas outlets 60p and 60o do not mix within the cooling duct 40. Furthermore, this partition plate 61a evenly distributes the cooling gas to the two adjacent cooling gas outlets 60p and 60o, so that approximately equal flow rates of cooling gas flow out from each cooling gas outlet 60p and 60o.

[0040] Next, using Figure 8, we will describe the cooling gas inlet (41a, 41b), multiple cooling gas outlets (60a to 60p), and distribution channels (42a, 42b) of the cooling duct 40a. Note that while we will describe the cooling duct 40a below, the other cooling ducts (40b, 40c, 40d) have a similar configuration, so we will omit their description below.

[0041] Figure 8 is a cross-sectional view of the cooling duct 40a shown in Figure 4, taken along the arrow EE. Combustion gas flows through the cooling duct 40a shown in Figure 8 along the flow direction FD. The cooling duct 40a has two cooling gas inlets 41a and 41b that are substantially perpendicular to the flow direction of the combustion gas, and cooling gas flows in from the two cooling gas inlets 41a and 41b along the width direction WD, which is substantially perpendicular to the flow direction FD of the combustion gas. Multiple cooling gas outlets (62a to 62p) are arranged in the cooling duct 40a at different positions in the width direction WD.

[0042] Cooling gas flows in from the cooling gas inlet (first cooling gas inlet) 41a located on the right side of Figure 8, in the direction from right to left in Figure 8 (first direction). The cooling gas that flows from the cooling gas inlet 41a into the cooling duct 40a flows into the distribution channel (first distribution channel) 42a. The distribution channel 42a extends along the width direction WD and is a channel that distributes the cooling gas that flows into the cooling gas inlet 41a to each of the multiple cooling gas outlet holes (60a to 60h).

[0043] The distribution channel 42a comprises four cooling gas channels 42aA, 42aB, 42aC, and 42aD separated by four circular pipes, with each cooling gas channel forming an independent channel. The distribution channel 42a also includes a partition plate 61a, as shown in Figure 6, for each cooling gas channel. The partition plate 61a is a plate-shaped member made of a metal material such as iron or a heat-resistant material, positioned approximately horizontally above the height HD of each cooling gas channel (circular pipe).

[0044] The partition plate 61a is joined to each cooling gas passage by welding, so that cooling gas does not leak at the joint. Each cooling gas passage (circular pipe) is provided with two cooling gas outlet holes, and the cooling gas that flows into each cooling gas passage flows out into the mixing duct 10 through the two cooling gas outlet holes.

[0045] Cooling gas flows in from the cooling gas inlet (second cooling gas inlet) 41b, located on the left side of Figure 8, in the direction from left to right in Figure 8 (second direction). The cooling gas that flows from the cooling gas inlet 41b into the cooling duct 40a flows into the distribution channel (second distribution channel) 42b. The distribution channel 42b is a channel that distributes the cooling gas that flows into the cooling gas inlet 41b to each of the multiple cooling gas outlet holes (60i to 60p).

[0046] The distribution channel 42b comprises four cooling gas channels 42bA, 42bB, 42bC, and 42bD separated by four circular pipes, with each cooling gas channel forming an independent channel. The distribution channel 42b also provides each cooling gas channel with a partition plate (not shown) similar to the partition plate 61a shown in Figure 6. The partition plate is a plate-shaped member made of a metal material such as iron or a heat-resistant material, positioned approximately horizontally above the height HD of each cooling gas channel (circular pipe).

[0047] The partition plates are joined to each cooling gas passage by welding, ensuring that cooling gas does not leak at the joints. Each cooling gas passage (circular pipe) is provided with two cooling gas outlet holes, and the cooling gas flowing into each passage flows out into the mixing duct 10 through these two outlet holes.

[0048] The distribution channel 42a and the distribution channel 42b are separated by partition plates 62a and 62b. The partition plates 62a and 62b are plate-shaped members made of metal such as iron or a heat-resistant material, positioned approximately horizontally in the cooling gas channel (circular pipe). The partition plates 62a and 62b are joined to the inner circumferential surface of the cooling duct 40a by welding, respectively, to block the flow path of the cooling gas channel (circular pipe), and to prevent cooling gas leakage at the joint. A gap is provided between the partition plates 62a and 62b in advance to account for the thermal expansion of the cooling duct 40 due to combustion gas.

[0049] Here, the shape of the cooling gas outlet 60 of the cooling duct 40 will be explained with reference to Figures 9 to 11. Figure 9 is a partially enlarged view of the cooling gas flow path 42bD that constitutes the cooling duct 40a shown in Figure 5. As shown in Figure 9, the cooling gas flow path 42bD is a circular flow path that extends along the central axis X1. A cooling gas outlet 60p is formed in the cooling gas flow path 42bD. Figure 9 shows the cooling gas outlet 60p, but the cooling gas outlets 60a, 60c, 60e, 60g, 60j, 60l, and 60n are similar.

[0050] As shown in Figure 9, the cooling gas outlet 60p is formed to allow the cooling gas to flow into the mixing duct 10 at an inclination angle θd that is inclined upward with respect to the flow direction FD in a plane perpendicular to the width direction WD. The cooling gas outlet 60p is formed along the circumferential direction CD around the central axis X1 of the cooling gas flow path 42bD from the first end P1 to the second end P2. The inclination angle θd is the angle that passes through the intermediate part P3 between the first end P1 and the second end P2 in the circumferential direction CD.

[0051] In Figure 9, the angle between the line passing through the central axis X1 and the first end P1 and the direction of flow FD is θe1, and the angle between the line passing through the central axis X1 and the second end P2 and the direction of flow FD is θe2. The inclination angles θd, θe1, and θe2 are set to satisfy the following equation (2). θd=(θe1+θe2) / 2 (2)

[0052] Furthermore, θd is set to a value that satisfies the range of equation (3) below. 45° < θd < 90° (3) θd is more preferably set to a value that satisfies the range of equation (4) below. 45° < θd ≤ 60° (4)

[0053] Figure 10 is a partially enlarged view of the cooling gas flow path 42bD that constitutes the cooling duct 40a shown in Figure 7. As shown in Figure 10, the cooling gas flow path 42bD is a circular flow path that extends along the central axis X2. A cooling gas outlet 60o is formed in the cooling gas flow path 42bD. Figure 10 shows the cooling gas outlet 60o, but the cooling gas outlets 60b, 60d, 60f, 60h, 60i, 60k, and 60m are similar.

[0054] As shown in Figure 10, the cooling gas outlet 60o is formed to allow the cooling gas to flow into the mixing duct 10 at an inclination angle θf that is inclined downward with respect to the flow direction FD in a plane perpendicular to the width direction WD. The cooling gas outlet 60o is formed along the circumferential direction CD around the central axis X2 of the cooling gas flow path 42bD from the first end P4 to the second end P5. The inclination angle θf is the angle that passes through the intermediate part P6 between the first end P4 and the second end P5 in the circumferential direction CD.

[0055] In Figure 10, the angle between the line passing through the central axis X2 and the first end P4 and the direction of flow FD is θg1, and the angle between the line passing through the central axis X2 and the second end P5 and the direction of flow FD is θg2. The inclination angles θf, θg1, and θg2 are set to satisfy the following equation (5). θf=(θg1+θg2) / 2 (5)

[0056] Furthermore, θf is set to a value that satisfies the range of equation (6) below. 45° < θf < 90° (6) θf is more preferably set to a value that satisfies the range of equation (7) below. 45° < θf ≤ 60° (7)

[0057] Figure 11 is a perspective view of the cooling gas flow path 42bD shown in Figure 9. As shown in Figure 11, the cooling gas introduced from the cooling gas inlet 41b into the cooling gas flow path 42bD is guided along the width direction WD to the cooling gas outlet holes 60o and 60p. In the width direction WD, a partition plate 61a is positioned between the cooling gas outlet holes 60p and 60o, on the upper side in the height direction HD.

[0058] Therefore, the cooling gas flowing above the cooling gas passage 42bD hits the partition plate 61a and flows upward from the cooling gas outlet hole 60p into the mixing duct 10. Meanwhile, the cooling gas passage 42bD under The cooling gas flowing on one side passes below the partition plate 61a and flows downward from the cooling gas outlet hole 60o into the mixing duct 10.

[0059] The combustion gas cooling device described in the embodiments above can be understood, for example, as follows. The combustion gas cooling device according to this disclosure comprises: a first duct (10) having a first inlet (10a) into which combustion gas flows and a first outlet (10b) through which the combustion gas flowing in from the first inlet flows out; a cooling duct (40) that discharges a cooling gas at a lower temperature than the combustion gas into the first duct to generate a mixed gas of the combustion gas and the cooling gas; and a second duct (20) connected to the first duct and having a second inlet (20a) into which the mixed gas flows and a second outlet (20b) through which the mixed gas flowing in from the second inlet flows out, wherein the first duct has a shape in which the cross-sectional area is equal at each position from the first inlet to the first outlet, and the second duct has a shape in which the cross-sectional area gradually increases from the second inlet to the second outlet.

[0060] According to the combustion gas cooling device described herein, the combustion gas flowing from the first inlet into the first duct and the cooling gas flowing out of the cooling duct into the first duct are mixed to form a mixed gas at a lower temperature than the combustion gas. The first duct has a shape in which the cross-sectional area is equal at each position from the first inlet to the first outlet. Therefore, compared to the case in which the first duct has a shape in which the cross-sectional area gradually increases, the combustion gas and cooling gas flowing linearly along the flow direction have a width perpendicular to the flow direction. direction This ensures good mixing at each position and prevents uneven temperature distribution in the width direction.

[0061] The mixed gas, which is mixed in the first duct without any bias in the temperature distribution in the width direction, flows into the second inlet of the second duct, where mixing is promoted in the second duct where the cross-sectional area gradually increases, and then flows out from the second outlet. In this way, the combustion gas cooling device according to the present disclosure allows the catalyst to exhibit the desired performance without increasing manufacturing costs.

[0062] In the combustion gas cooling device according to the present disclosure, the cooling duct includes a cooling gas inlet (41a, 41b) into which the cooling gas flows, a plurality of cooling gas outlets (60a to 60p) that cause the cooling gas flowing in from the cooling gas inlet to flow out into the first duct, and a cooling gas flow path that extends along the width direction (WD) intersecting the flow direction of the combustion gas and guides the cooling gas from the cooling gas inlet to the cooling gas outlet. 42aA,42aB,42aC,42aD,42bA,42bB,42bC,42bD Preferably, the cooling gas outlet section is formed such that, in a plane perpendicular to the width direction, the cooling gas is discharged into the first duct at an inclination angle greater than 45 degrees and less than 90 degrees with respect to the flow direction.

[0063] In the combustion gas cooling device according to this configuration, multiple cooling gas outlets that discharge the cooling gas into the first duct discharge the cooling gas into the first duct at an inclination angle greater than 45 degrees with respect to the flow direction in a plane perpendicular to the width direction. Therefore, compared to the case where the inclination angle is 45 degrees or less, the angle between the flow direction of the combustion gas and the discharge direction of the cooling gas becomes sufficiently large, and the mixing of the combustion gas and the cooling gas can be sufficiently promoted.

[0064] Furthermore, in the combustion gas cooling device according to this configuration, the multiple cooling gas outlets that discharge the cooling gas into the first duct discharge the cooling gas into the first duct at an inclination angle of less than 90 degrees with respect to the flow direction in a plane perpendicular to the width direction. Therefore, compared to the case where the inclination angle is 90 degrees or more, it is possible to suppress the problem of combustion gas flowing into the cooling gas outlets.

[0065] In the combustion gas cooling device with the above configuration, it is preferable that the inclination angle is 60 degrees or less. By setting the inclination angle of the cooling gas outlet direction relative to the flow direction to 60 degrees or less, the problem of combustion gas flowing into the cooling gas outlet can be more reliably suppressed.

[0066] In the combustion gas cooling device with the above configuration, the cooling duct extends along the width direction and has a circular cross-section perpendicular to the width direction, the cooling gas outlet is an opening having a predetermined length along the width direction, the opening is formed from a first end (P1) to a second end (P2) along the circumferential direction around the central axis of the cooling duct, and the inclination angle is preferably an angle that passes through the intermediate part (P3) between the first end and the second end in the circumferential direction.

[0067] According to the combustion gas cooling device of this embodiment, cooling gas can be discharged into the first duct from an opening in a cooling duct having a circular cross-section perpendicular to the width direction and mixed with the combustion gas. The direction in which the cooling gas discharges from the opening into the first duct passes through the intermediate portion between the first and second ends in the circumferential direction of the opening, and the angle between this direction and the flow direction of the combustion gas is the aforementioned inclination angle.

[0068] The combustion gas cooling device according to this disclosure comprises a first duct through which combustion gas flows, and a cooling duct that discharges a cooling gas at a lower temperature than the combustion gas into the first duct to generate a mixed gas of the combustion gas and the cooling gas. The cooling duct has a cooling gas inlet into which the cooling gas flows, a plurality of cooling gas outlets that discharge the cooling gas that has flowed in from the cooling gas inlet into the first duct, and a cooling gas flow path that extends along a width direction intersecting the flow direction of the combustion gas and guides the cooling gas from the cooling gas inlet to the cooling gas outlets. The cooling gas outlets are formed to discharge the cooling gas into the first duct at an inclination angle greater than 45 degrees and less than 90 degrees with respect to the flow direction in a plane perpendicular to the width direction.

[0069] According to the combustion gas cooling device described herein, the combustion gas flowing from the first inlet into the first duct and the cooling gas flowing out from the cooling duct into the first duct are mixed to form a mixed gas at a lower temperature than the combustion gas. Multiple cooling gas outlets that discharge the cooling gas into the first duct discharge the cooling gas into the first duct at an inclination angle greater than 45 degrees with respect to the flow direction in a plane perpendicular to the width direction. Therefore, compared to the case where the inclination angle is 45 degrees or less, the angle between the flow direction of the combustion gas and the discharge direction of the cooling gas becomes sufficiently large, and the mixing of the combustion gas and the cooling gas can be sufficiently promoted.

[0070] Furthermore, according to the combustion gas cooling device described herein, the multiple cooling gas outlets that discharge the cooling gas into the first duct discharge the cooling gas into the first duct at an inclination angle of less than 90 degrees with respect to the flow direction in a plane perpendicular to the width direction. Therefore, compared to the case where the inclination angle is 90 degrees or more, it is possible to suppress the problem of combustion gas flowing into the cooling gas outlets.

[0071] In the combustion gas cooling device with the above configuration, it is preferable that the inclination angle is 60 degrees or less. By setting the inclination angle of the cooling gas outlet direction relative to the flow direction to 60 degrees or less, the problem of combustion gas flowing into the cooling gas outlet can be more reliably suppressed.

[0072] In the combustion gas cooling device with the above configuration, the cooling duct extends along the width direction and has a circular cross-section perpendicular to the width direction, the cooling gas outlet is an opening having a predetermined length along the width direction, the opening is formed from a first end to a second end along the circumferential direction around the central axis of the cooling duct, and the inclination angle is preferably an angle that passes through the intermediate portion between the first end and the second end in the circumferential direction.

[0073] According to the combustion gas cooling device of this embodiment, cooling gas can be discharged into the first duct from an opening in a cooling duct having a circular cross-section perpendicular to the width direction and mixed with the combustion gas. The direction in which the cooling gas discharges from the opening into the first duct passes through the intermediate portion between the first and second ends in the circumferential direction of the opening, and the angle between this direction and the flow direction of the combustion gas is the aforementioned inclination angle.

[0074] The combustion gas cooling device according to this disclosure may also be configured to include a catalyst that decomposes nitrogen oxides contained in the mixed gas and discharges the mixed gas from which the nitrogen oxides have been decomposed. This combustion gas cooling system configuration allows the catalyst to perform as desired without increasing manufacturing costs. [Explanation of Symbols]

[0075] 1 Inlet duct 10. Mixing duct (Duct 1) 10a Inlet 10b Outlet 20. Expansion duct (second duct) 20a Inlet 20b Outlet 30 Catalyst section 40, 40a, 40b, 40c, 40d Cooling duct 41a, 41b Cooling gas inlet 42a, 42b Distribution channel 42aA, 42aB, 42aC, 42aD, 42bA, 42bB, 42bC, 42bD Cooling gas flow path 60 Cooling gas outlet holes 61a, 62a, 62b Partition plates 100 Denitrification equipment (combustion gas cooling equipment) CD circumferential direction FD flow direction HD Height Direction P1,P4 1st end P2,P5 2nd end P3,P6 middle part WD width direction X1,X2 center axis θd, θf tilt angles

Claims

1. A first duct comprising a first inlet into which combustion gas flows, and a first outlet outlet into which the combustion gas that has flowed in from the first inlet flows out, A cooling duct that discharges a cooling gas at a lower temperature than the combustion gas into the first duct, thereby generating a mixed gas of the combustion gas and the cooling gas, The system includes a second duct connected to the first duct and comprising a second inlet into which the mixed gas flows, and a second outlet outlet into which the mixed gas that has flowed in from the second inlet flows out, The first duct has a shape in which the cross-sectional area is equal at each position from the first inlet to the first outlet, The second duct is a combustion gas cooling device having a shape in which the cross-sectional area gradually increases from the second inlet to the second outlet.

2. The aforementioned cooling duct is The cooling gas inlet into which the cooling gas flows, A plurality of cooling gas outlets that allow the cooling gas flowing in from the cooling gas inlet to flow into the first duct, It has a cooling gas flow path that extends along the width direction intersecting the flow direction of the combustion gas and guides the cooling gas from the cooling gas inlet to the cooling gas outlet, The combustion gas cooling device according to claim 1, wherein the cooling gas outlet is formed such that, in a plane perpendicular to the width direction, the cooling gas is discharged into the first duct at an inclination angle greater than 45 degrees and less than 90 degrees with respect to the flow direction.

3. The combustion gas cooling device according to claim 2, wherein the inclination angle is 60 degrees or less.

4. The cooling duct extends along the width direction and has a circular cross-section perpendicular to the width direction. The cooling gas outlet is an opening having a predetermined length along the width direction, The aforementioned opening is formed along the circumferential direction around the central axis of the cooling duct from the first end to the second end, The combustion gas cooling device according to claim 2 or 3, wherein the inclination angle is an angle that passes through the intermediate portion between the first end and the second end in the circumferential direction.

5. A combustion gas cooling device according to any one of claims 1 to 4, comprising a catalyst unit that decomposes nitrogen oxides contained in the mixed gas and discharges the mixed gas from which the nitrogen oxides have been decomposed.

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