Boiler and composite boiler

Abstract

This boiler comprises: a cylindrical drum; a combustion chamber that is disposed inside the drum and that is provided with a combustion space; a burner that ejects ammonia fuel containing ammonia into the combustion space; a plurality of smoke pipes that are disposed inside the drum, that are connected to the combustion chamber, and that circulate combustion gas generated by combustion of the ammonia fuel; and a restriction member that is disposed inside the combustion chamber and that restricts at least a portion of the flow of the combustion gas toward the smoke pipes.

Description

Boiler, Composite Boiler

[0001] The present invention relates to a boiler and a composite boiler including the boiler. The present application claims priority based on Japanese Patent Application No. 2025-053268 filed in Japan on March 27, 2025, the content of which is incorporated herein by reference.

[0002] In recent years, from the perspective of reducing carbon dioxide emissions and the like, the use of ammonia fuel containing ammonia, which does not emit carbon dioxide during combustion, has been expanding. Compared with petroleum fuels, ammonia fuel has characteristics such as a higher ignition temperature and a slower combustion speed, and various measures have been taken to improve its combustibility (see, for example, Patent Document 1).

[0003] Japanese Unexamined Patent Publication No. 2016-130619

[0004] When ammonia fuel is combusted, flames tend to be larger than when petroleum fuel is combusted. On the other hand, marine boilers are arranged in limited onboard space, and it is difficult to increase the size of the combustion chamber for ammonia fuel. In particular, a composite boiler incorporates both a fuel combustion section and a main engine exhaust gas introduction section in the same drum so that it can be used not only as an auxiliary boiler that generates steam by burning fuel but also as an exhaust gas economizer that uses main engine exhaust gas as a heat source, and is characterized by being lower in cost and more space-saving compared to the case where an auxiliary boiler and an exhaust gas economizer are installed separately. For this reason, it is not practical to increase the size of the combustion chamber arranged in the drum of the composite boiler.

[0005] On the other hand, when ammonia fuel is combusted in a conventional combustion chamber, the combustion gas flows into the smoke tubes before the ammonia fuel is completely combusted, resulting in unburned substances (unburned ammonia, dinitrogen monoxide (N ２ O), carbon monoxide (CO), etc.) being released into the atmosphere as exhaust gas containing these unburned substances, which is a problem. Therefore, there is a need for a boiler that can suppress the generation of unburned substances from ammonia fuel by promoting ammonia combustion in the combustion chamber without significantly increasing the size of the conventional combustion chamber, and a composite boiler including the same.

[0006] The object of the present invention is to provide a boiler that can suppress the generation of unburned ammonia fuel by promoting ammonia combustion in the combustion chamber without significantly increasing the size of the combustion chamber, and a composite boiler equipped with the same.

[0007] The present invention solves the above problem by the following means.

[0008] (1) The boiler of the present invention comprises a cylindrical drum, a combustion chamber disposed within the drum and having a combustion space, a burner that injects ammonia fuel containing ammonia into the combustion space, a plurality of flames disposed within the drum and connected to the combustion chamber, through which combustion gas generated by the combustion of the ammonia fuel flows, and a limiting member disposed within the combustion chamber that restricts at least a portion of the flow of the combustion gas toward the flames.

[0009] (2) Furthermore, it is preferable that the main body of the limiting member located in the combustion space is a plate-shaped member, dividing the combustion space into a flue tube side and a non-flue tube side, and that the burner injects the ammonia fuel into the non-flue tube side.

[0010] (3) Furthermore, it is preferable that the main body of the limiting member located in the combustion space is a cylindrical member, dividing the combustion space into the inside of the cylindrical member and the outside of the cylindrical member, and that the burner is positioned at one end of the cylindrical member and injects the ammonia fuel into the inside of the cylindrical member.

[0011] (4) The limiting member also comprises a main body located in the combustion space, a cylindrical member and a plate-shaped member extending from the tip of the cylindrical member in the axial direction of the cylindrical member and located on the pipe side with respect to the central axis of the cylindrical member, thereby dividing the combustion space into the inside of the cylindrical member, the pipe side with respect to the main body, and the non-pipe side with respect to the main body, and preferably the burner is positioned at the end of the cylindrical member on the side opposite to the plate-shaped member in the axial direction of the cylindrical member, and injects the ammonia fuel into the inside of the cylindrical member.

[0012] (5) Furthermore, it is preferable that the volume of the cylindrical member is 1 / 2 or less of the volume of the combustion space.

[0013] (6) Furthermore, the cylindrical member is preferably cylindrical in shape, and the length of the cylindrical member is preferably one to three times the inner diameter of the cylindrical member.

[0014] (7) Furthermore, it is preferable that the cross-sectional area of ​​the hollow portion of the cylindrical member is less than or equal to the area of ​​the inner surface of the extended portion when the inner surface of the cylindrical member is extended along the axial direction from the tip of the cylindrical member to the inner wall of the combustion chamber.

[0015] (8) The composite boiler of the present invention comprises the boiler described above and a main engine exhaust heat recovery boiler equipped with a plurality of second fire tubes through which the main engine exhaust gas flows, wherein the exhaust gas outlet of the boiler and the main engine exhaust gas outlet of the main engine exhaust heat recovery boiler are provided separately.

[0016] According to the present invention, it is possible to provide a boiler that can suppress the generation of unburned ammonia fuel by promoting ammonia combustion in the combustion chamber without significantly increasing the size of the combustion chamber, and a composite boiler equipped with the same.

[0017] This is a diagram illustrating the boiler 10 of the first embodiment. This is a diagram illustrating the limiting member 15 of the first embodiment. This is a diagram illustrating the flow of combustion gas G1 in the combustion chamber 13 of the boiler 10 of the first embodiment. This is a diagram illustrating the flow of combustion gas G1 in the combustion chamber 13 of the comparative example boiler 10B. This is a diagram illustrating the cross-sectional area M1 of the hollow portion of the main body 151 and the area M2 of the inner circumferential surface of the virtual extension portion. This is a diagram illustrating the limiting member 25 of the second embodiment. This is a diagram illustrating the flow of combustion gas G1 in the combustion chamber 13 of the boiler 20 of the second embodiment. This is a diagram illustrating the limiting member 35 of the third embodiment. This is a diagram illustrating the flow of combustion gas G1 in the combustion chamber 13 of the boiler 30 of the third embodiment. This is a diagram illustrating the composite boiler 1 of the fourth embodiment.

[0018] Embodiments of the present invention will be described below with reference to the drawings and other figures. Note that the following figures, including Figure 1, are schematic representations, and the size and shape of each part have been exaggerated as appropriate for ease of understanding.

[0019] (First Embodiment) Figure 1 is a diagram illustrating a boiler 10 of the first embodiment. The boiler 10 of the first embodiment includes a drum 11, a burner 12, a combustion chamber 13, a plurality of fire tubes 14, a limiting member 15, and a smoke chamber 16. The boiler 10 also includes an ammonia fuel supply line L200, a first fuel supply line L100, an air supply line L300, a feedwater line L400, an exhaust gas discharge line L500, and a steam supply line L600. The boiler 10 is a fire-tube boiler installed on a ship or the like. In this specification, "line" is a general term for a flow path, route, pipeline, etc.

[0020] Boiler 10 is an ammonia co-firing boiler that simultaneously burns ammonia fuel F2 and a first fuel F1 which burns faster than ammonia fuel F2. In addition, in the combustion chamber 13, boiler 10 burns the ammonia fuel F2 and the first fuel F1 ejected from the burner 12, and the combustion gas G1 heats the boiler water W2 in the drum 11 to generate steam. However, boiler 10 is not limited to this configuration and may burn only ammonia fuel F2.

[0021] Ammonia fuel F2 is a fuel containing ammonia, and includes not only ammonia alone, but also ammonia-containing mixed gases and ammonia decomposition gases produced by the decomposition of ammonia. In this embodiment, ammonia fuel F2 will be described using ammonia as an example. First fuel F1 is a fuel with a faster combustion rate than ammonia. First fuel F1 can be a liquid fuel such as oil fuel, alcohol fuel, or biofuel, or a gaseous fuel such as hydrogen-based fuel gas, natural gas, or petroleum gas. In this embodiment, first fuel F1 will be described using heavy oil as an example.

[0022] The drum 11 is a cylindrical member capable of storing water internally. Inside the drum 11 are a burner 12, a combustion chamber 13, a flue tube 14, and a smoke chamber 16, with the combustion chamber 13 and flue tube 14 located within the boiler water W2 (water stored inside the drum 11). In this embodiment, the drum 11 is positioned so that the central axis of its cylindrical shape is in the vertical direction.

[0023] The burner 12 injects ammonia fuel F2, first fuel F1, and combustion air A1 into the combustion space of the combustion chamber 13. The burner 12 includes an ammonia fuel supply pipe (not shown), a first fuel supply pipe, and a wind box 121. The ammonia fuel supply pipe is connected to an ammonia fuel supply line L200, and the first fuel supply pipe is connected to a first fuel supply line L100. The wind box 121 is connected to an air supply line L300. The burner 12 is installed so as to be inserted from the outer circumferential surface of the drum 11 into the burner mounting portion 136 of the combustion chamber 13. The wind box 121 is located outside the drum 11 and is installed so as to sandwich the flange-shaped portion 153 of the limiting member 15 (described later) between the wind box 121 and a flange-shaped portion 135 provided at one end of the burner mounting portion 136 located outside the drum 11.

[0024] The burner 12 in this embodiment is a pre-mixed type burner in which ammonia fuel F2 and first fuel F1 are injected from separate nozzles. However, the burner 12 is not limited to this, and when a gaseous fuel is used as the first fuel F1, it may be a pre-mixed burner in which at least a portion of the first fuel F1 and combustion air A1 are pre-mixed and injected.

[0025] The combustion chamber 13 is located at the bottom of the drum 11 and is situated in the boiler water W2. Inside the combustion chamber 13, fuels and combustion air A1 are ejected from the burner 12, and a combustion space is provided where the fuels burn. Multiple flue tubes 14 are connected to the upper surface of the combustion chamber 13. In this embodiment, the combustion space of the combustion chamber 13 is cylindrical and has a rectangular cross-sectional shape with points E, F, G, and H as vertices in Figure 1. The combustion chamber 13 also has a burner mounting portion 136 and a flange-shaped portion 135 that communicate with the combustion space and into which the burner 12 and limiting member 15 can be inserted. One end of the burner mounting portion 136 is located outside the drum 11, and the flange-shaped portion 135 is provided so as to protrude outward from the end of the burner mounting portion 136 that is located outside the drum 11. This flange-shaped portion 135 corresponds to a holding portion that holds the limiting member 15, and the limiting member 15 is supported by being sandwiched between the flange-shaped portion 135 and the window box 121, which will be described later, by the flange-shaped portion 153 of the limiting member 15.

[0026] The flue tube 14 is a tube through which the combustion gas G1 generated in the combustion chamber 13 flows. Multiple flue tubes 14 are provided at predetermined intervals within the drum 11 and are located within the boiler water W2 inside the drum 11. The flue tube 14 extends in the vertical direction (along the central axis of the drum 11), with one end connected to the upper surface of the combustion chamber 13 and the other end connected to the smoke chamber 16. The combustion gas G1 flows from the combustion chamber 13 through the flue tube 14 to the smoke chamber 16. As the combustion gas G1 flows through the flue tube 14, the boiler water W2 surrounding the flue tube 14 is heated.

[0027] The ammonia fuel supply line L200 is connected to the burner 12 and supplies ammonia fuel F2 to the burner 12 from an ammonia fuel supply source (not shown). The first fuel supply line L100 is connected to the burner 12 and supplies first fuel F1 to the burner 12 from a first fuel supply source (not shown). The air supply line L300 is connected to the wind box 121 and supplies combustion air A1 to the burner 12.

[0028] The water supply line L400 supplies water W1 into the drum 11. The water W1 is stored in the drum 11 and becomes boiler water W2. The exhaust gas discharge line L500 is connected to the smoke chamber 16 and discharges the exhaust gas (combustion gas after heat exchange in the flue tube 14) to the outside of the system. The steam supply line L600 is connected to the top of the drum 11 and supplies the generated steam to the steam demand section (not shown). The first fuel supply line L100, ammonia fuel supply line L200, air supply line L300, water supply line L400, exhaust gas discharge line L500, and steam supply line L600 are each appropriately equipped with shut-off valves, flow control valves, pressure sensors, etc. (not shown).

[0029] The restricting member 15 is positioned within the combustion chamber 13 and restricts at least a portion of the flow of combustion gas G1 toward the flue pipe 14, thereby promoting combustion. The restricting member 15 is provided to be inserted into the combustion space of the combustion chamber 13 from the outer circumferential surface of the drum 11. The restricting member 15 has a main body portion 151 located in the combustion space of the combustion chamber 13, and a mounting portion 152 provided on one end of the main body portion 151, with at least a portion of it located within the burner mounting portion 136 of the combustion chamber 13.

[0030] Figure 2 is a diagram illustrating the limiting member 15 of the first embodiment. Figure 2 shows a perspective view of the limiting member 15. The main body 151 is a cylindrical member, and in this embodiment it is cylindrical in shape. The mounting portion 152 is also cylindrical in shape. The main body 151 and the mounting portion 152 have the same central axis and diameter and are integrally formed. As shown in Figure 1, the inner wall surface of the burner mounting portion 136 of the combustion chamber 13 and the outer wall surface of the mounting portion 152 are spaced apart and do not touch. However, this is not limited to this, and the inner wall surface of the burner mounting portion 136 may be provided to support (or fix) the outer wall surface of the mounting portion 152. Also, the inner wall surface of the mounting portion 152 and the outer circumferential surface of the burner 12 are spaced apart and do not touch.

[0031] The main body 151 is located in the combustion space of the combustion chamber 13. The main body 151 is positioned to protrude from the inner wall of the combustion chamber 13 into the combustion space of the combustion chamber 13. Furthermore, the main body 151 is positioned so that its longitudinal direction intersects with the longitudinal direction of the flue pipe 14 within the combustion chamber 13. In this embodiment, the longitudinal direction of the main body 151 is horizontal.

[0032] The mounting portion 152 is located at least partly within the burner mounting portion 136 and is the portion that attaches the limiting member 15 to the combustion chamber 13. The mounting portion 152 has a flange-shaped portion 153 on its outer circumferential surface. The burner 12 is located inside the mounting portion 152. The limiting member 15 and the burner 12 are arranged so that the central axes of the main body portion 151 and the mounting portion 152 are parallel to the ejection central axis of the burner 12.

[0033] The flange portion 153 is a flange-shaped part that protrudes outward on the outer diameter side of the mounting portion 152, and is held in place within the combustion chamber 13 by being sandwiched between the flange portion 135 of the combustion chamber 13 and the window box 121. In this embodiment, as an example, the flange portion 153 is described as having an annular shape that protrudes outward along the radial direction of the cylindrical shape of the mounting portion 152 and is continuous in the circumferential direction. However, it is not limited to this, and the flange portion 153 may have a form that is not continuous in the circumferential direction, for example, a form in which multiple plate-shaped portions that protrude radially are formed in the circumferential direction.

[0034] The limiting member 15 does not have a complex holding mechanism for the drum 11 or combustion chamber 13. As described above, the flange-shaped portion 153 is sandwiched between the flange-shaped portion 135 of the combustion chamber 13 and the window box 121, so that it protrudes into the combustion space of the combustion chamber 13. Furthermore, by removing the window box 121, the limiting member 15 can also be easily removed, and the limiting member 15 can be easily attached to and detached from the drum 11, making maintenance and inspection easy.

[0035] The limiting member 15 has at least its surface made of a material with low thermal conductivity and high temperature resistance. Suitable materials for this purpose include refractory materials such as ceramics and radiant materials such as SiC. The limiting member 15 may be made of a refractory material, or it may be made of a metal core with its surface covered by a refractory material.

[0036] In this embodiment, the restricting member 15, with its cylindrical main body 151, divides the combustion space of the combustion chamber 13 into an internal 131 and an external 132 of the cylindrical member. The burner 12 is located within the mounting portion 152 and injects ammonia fuel F2, first fuel F1, and combustion air A1 into the internal 131 of the cylindrical member. As a result, the restricting member 15 (particularly the main body 151) can restrict at least a portion of the flow of combustion gas G1.

[0037] Figure 3 illustrates the flow of combustion gas G1 in the combustion chamber 13 of the boiler 10 of the first embodiment. Figure 4 illustrates the flow of combustion gas G1 in the combustion chamber 13 of the boiler 10B of the comparative example. In Figures 3 and 4, for ease of understanding, a cross-section of the combustion chamber 13 and its vicinity is shown, passing through the central axis of the burner 12 and parallel to the vertical direction.

[0038] The comparative example boiler 10B differs from the boiler 10 of the first embodiment in that it does not have a limiting member 15, but otherwise it is similar in form to the boiler 10 of the first embodiment. In both the boiler 10 of the first embodiment and the comparative example boiler 10B, the burner 12 ejects the first fuel F1, ammonia fuel F2, and combustion air A1. As shown in Figure 4, in the comparative example boiler 10B, which does not have a limiting member 15, the combustion gas G1 spreads into the combustion space of the combustion chamber 13 as soon as combustion starts. As a result, some of the combustion gas G1 flows into the fire tube 14 containing unburned material and is cooled, and as a result, unburned material remains in the exhaust gas. In addition, some of the combustion gas G1 is cooled by the water-cooled wall of the combustion chamber 13, causing its temperature to drop, resulting in insufficient combustion and the generation of unburned material.

[0039] In contrast, as shown in Figure 3, in the boiler 10 of this embodiment, the first fuel F1 and ammonia fuel F2 are injected into the cylindrical member interior 131, which is the space inside the main body 151 of the limiting member 15, and combustion takes place inside the cylindrical member interior 131. The combustion gas G1 is then injected to the outside of the cylindrical member 132, flows along the outside of the cylindrical member 132, and enters the fire tube 14. Therefore, in the boiler 10 of the first embodiment, the combustion gas G1 containing unburned material is prevented from diffusing unrestricted in the combustion space of the combustion chamber 13 and the fire tube 14, and the volume of the space inside the cylindrical member interior 131 is limited, so the combustion gas G1 is maintained at a high temperature. As a result, in the boiler 10 of this embodiment, a reaction time at a temperature that promotes the combustion of combustion gas G1 is secured, and combustion is promoted, so the generation of unburned material in the ammonia fuel F2 is suppressed, and the amount of unburned material contained in the exhaust gas of the boiler 10 is reduced.

[0040] From the viewpoint of enhancing the effect of promoting the combustion of ammonia fuel F2, it is preferable that the limiting member 15 satisfies the following conditions. The limiting member 15 of this embodiment satisfies these conditions. First, it is preferable that the volume of the main body portion 151, which is a cylindrical member, is 1 / 2 or less of the volume of the combustion space of the combustion chamber 13. By limiting the volume of the main body portion 151 to the above range, the combustion gas G1 inside the cylindrical member 131 is maintained in a high-temperature state in which combustion is promoted, and a reaction time at a temperature in which combustion is promoted is ensured, thereby promoting the combustion of ammonia fuel F2 and enhancing the effect of suppressing the generation of unburned ammonia fuel F2.

[0041] Furthermore, it is preferable that the length (longitudinal dimension) S of the main body portion 151, which is a cylindrical member, is between 1 and 3 times the inner diameter D of the main body portion 151. By satisfying the above range for the length S of the main body portion 151, combustion inside the cylindrical member 131 can be promoted even when burning ammonia fuel F2, which tends to have a slower combustion rate and longer flame length compared to the first fuel F1 such as petroleum fuel.

[0042] Furthermore, it is preferable that the cross-sectional area M1 of the hollow portion of the main body 151, which is a cylindrical member, is less than or equal to the area M2 of the inner circumferential surface of the extended portion when the inner circumferential surface of the main body 151 is extended along the axial direction from the tip of the main body 151, which is a cylindrical member, to the inner wall of the combustion chamber 13. Figure 5 is a diagram illustrating the cross-sectional area M1 of the hollow portion of the main body 151 and the area M2 of the inner circumferential surface of the hypothetical extended portion. As shown in Figure 5, the cross-sectional area M1 of the hollow portion of the main body 151 is the area of ​​the hollow portion in the cross-section (transverse plane) in a direction perpendicular to the central axis of the main body 151.

[0043] Furthermore, the inner circumferential surface of the virtual extension is the extension that occurs when the inner circumferential surface of the main body 151 is extended axially from the tip of the cylindrical main body 151 to the inner wall of the combustion chamber 13. In Figure 5, the cylinder shown by the dashed line represents the inner circumferential surface of the main body 151 and its extension, and the inner circumferential surface of the virtual extension corresponds to the outer circumferential surface of the portion of that cylinder that extends from the tip of the main body 151. The area of ​​the inner circumferential surface of this virtual extension (the outer circumferential surface of the portion of the cylinder shown by the dashed line in Figure 5 that is closer to the tip of the main body 151) is area M2. The area of ​​the inner circumferential surface of this virtual extension serves as an indicator of the flow path area when the combustion gas G1 ejected from the main body 151 hits the wall of the combustion chamber 13 and changes its flow direction. If the area M2 of the inner surface of the virtual extension is smaller than the cross-sectional area M1 of the hollow part of the main body 151, the flow area of ​​the combustion gas G1 will be small, causing pressure loss and potentially reducing the flammability of the burner 12. Therefore, from the viewpoint of suppressing a decrease in the flammability of the burner 12, it is preferable that the cross-sectional area M1 of the hollow part of the main body 151 is greater than or equal to the area M2 of the inner surface of the virtual extension.

[0044] As described above, according to the present embodiment, the following effects can be obtained. (1) According to the boiler 10 of the present embodiment, a restriction member 15 that restricts at least a part of the flow of combustion gas G1 toward the smoke tube 14 is provided in the combustion chamber 13. Therefore, the restriction member 15 prevents the combustion gas G1 from diffusing into the combustion space when combustion starts, coming into contact with and being cooled by the smoke tube or the like before combustion is sufficiently promoted, resulting in insufficient combustion, and can suppress unburned substances from remaining in exhaust gas. Accordingly, the boiler 10 can suppress the generation of unburned substances (unburned ammonia, nitrous oxide, carbon monoxide, soot, etc.) of the ammonia fuel F2 by changing the flow of the combustion gas G1 and the temperature distribution in the combustion chamber 13 without significantly increasing the size of the combustion chamber 13.

[0045] (2) According to the boiler 10 of the present embodiment, the main body 151 of the restriction member 15 located in the combustion space of the combustion chamber 13 is a cylindrical member, which divides the combustion space into an inner space 131 of the cylindrical member and an outer space 132 of the cylindrical member, and the burner 12 injects the ammonia fuel F2 into the inner space 131 of the cylindrical member, so that combustion is performed inside the inner space 131 of the cylindrical member. This restriction member 15 can prevent the combustion gas G1 from flowing into the smoke tube 14 without being sufficiently combusted, and combustion is performed in the inner space 131 of the cylindrical member which is smaller than the combustion chamber 13 and has a restricted space. Accordingly, the combustion gas G1 can be maintained at a high temperature that promotes combustion, and the reaction time at a temperature that promotes combustion is secured, so that the combustion of the ammonia fuel F2 can be promoted. Therefore, the boiler 10 can suppress the generation of unburned substances of the ammonia fuel F2.

[0046] (3) According to the boiler 10 of the present embodiment, the volume of the main body 151 is 1 / 2 or less of the volume of the combustion space of the combustion chamber 13, so the boiler 10 can maintain the combustion gas G1 in the inner space 131 of the cylindrical member in a high temperature state that promotes combustion, and the reaction time at a temperature that promotes combustion is secured, thereby enhancing the effect of promoting the combustion of the ammonia fuel F2. Accordingly, the boiler 10 can enhance the effect of suppressing the generation of unburned substances of the ammonia fuel F2.

[0047] (4) According to the boiler 10 of the present embodiment, the main body portion 151, which is a cylindrical member, has a cylindrical shape, and the length of the main body portion 151 is not less than 1 time and not more than 3 times the inner diameter of the main body portion 151. Therefore, even when ammonia fuel F2, which has a slower combustion rate and tends to have a longer flame length than petroleum fuel or the like that is the first fuel F1, is combusted, combustion can be promoted inside the cylindrical member 131.

[0048] (5) According to the boiler 10 of the present embodiment, the cross-sectional area M1 of the hollow portion of the main body portion 151, which is a cylindrical member, is equal to or less than the area M2 of the inner peripheral surface of a virtual extended portion obtained by extending the inner peripheral surface of the main body portion 151 along the axial direction from the tip end of the main body portion 151 to the inner wall of the combustion chamber 13. Therefore, a decrease in combustibility of the burner 12 due to pressure loss, which may occur when the area (flow area) M2 of the inner peripheral surface of the virtual extended portion is smaller than the cross-sectional area M1 of the hollow portion of the main body portion 151, can be suppressed.

[0049] (Second Embodiment) Fig. 6 is a diagram illustrating a restricting member 25 according to a second embodiment. The boiler 20 of the second embodiment has the same configuration except that the shape of the restricting member 25 is different from that of the restricting member 15 of the first embodiment. Therefore, parts that perform the same functions as those in the above-described first embodiment are denoted by the same reference numerals, or the same reference numerals are given to the last one digit or the last two digits, and duplicate explanations are omitted as appropriate. The boiler 20 of the second embodiment includes a drum 11, a burner 12, a combustion chamber 13, a plurality of smoke tubes 14, a restricting member 25, and a smoke chamber 16. The boiler 20 also includes an ammonia fuel supply line L200, a first fuel supply line L100, an air supply line L300, a water supply line L400, an exhaust gas discharge line L500, and a steam supply line L600.

[0050] The restricting member 25 of the second embodiment is formed of the same material as the restricting member 15 of the first embodiment, but the shape of the main body portion 251 is different. The restricting member 25 includes a main body portion 251 which is a semi-cylindrical plate-shaped member, and a cylindrical attachment portion 252 provided on one end side of the main body portion 251. The attachment portion 252 is provided with a flange portion 253 similar to the flange portion 153 of the first embodiment.

[0051] The main body portion 251 is a semi-cylindrical shape that curves convexly toward the flue tube 14 side. The mounting portion 252 is cylindrical in shape. In this embodiment, the main body portion 251 and the mounting portion 252 have the same central axis and diameter and are integrally formed. The main body portion 251 is located above (towards the flue tube 14) the central axis of the mounting portion 252. It is preferable that the main body portion 251 is larger than the flame formed by the combustion of the first fuel F1 and ammonia fuel F2 ejected from the burner 12. That is, when viewing the combustion space of the combustion chamber 13 from the flue tube 14 side along the vertical direction of the drum 11 during combustion, it is preferable from the viewpoint of sufficiently restricting the flow of combustion gas G1 that the flame is hidden and not visible by the main body portion 251.

[0052] Figure 7 illustrates the flow of combustion gas G1 in the combustion chamber 13 of the boiler 20 of the second embodiment. In Figure 7, for ease of understanding, a cross-section of the combustion chamber 13 and its vicinity is shown, passing through the central axis of the burner 12 and parallel to the vertical direction. The limiting member 25 divides the combustion space of the combustion chamber 13 into a fire tube side portion 134 on the fire tube 14 side and a non-fire tube side portion 133 on the opposite side of the fire tube side portion 134 relative to the main body portion 251, by a plate-shaped main body portion 251.

[0053] In the boiler 20 of the second embodiment, combustion takes place in the non-fire tube side portion 133 partitioned by the main body portion 251 of the limiting member 25. This suppresses the unrestricted diffusion of combustion gas G1 containing unburned material into the combustion space and the fire tube 14, and because the volume of the space in the non-fire tube side portion 133 is limited, the combustion gas G1 is maintained at a high temperature. As a result, a reaction time at a temperature that promotes the combustion of combustion gas G1 is ensured, and the combustion of combustion gas G1 is promoted, thereby suppressing the generation of unburned material in the ammonia fuel F2 and reducing the amount of unburned material contained in the exhaust gas of the boiler 20. Therefore, even when the boiler 20 is equipped with a limiting member 25 as in this embodiment, at least a portion of the flow of combustion gas G1 can be restricted, and it is possible to prevent combustion gas G1 from flowing into the fire tube 14 without being fully burned.

[0054] Furthermore, since the volume of the non-fire-tube side portion 133 partitioned by the limiting member 25 is smaller than the volume of the combustion space of the combustion chamber 13, the combustion gas G1 can be maintained at a high temperature that promotes combustion, thereby promoting the combustion of the ammonia fuel F2. As a result, the boiler 20 can suppress the generation of unburned ammonia fuel F2.

[0055] According to this embodiment, in addition to (1) above, the following effects can be achieved. (6) According to the boiler 20 of this embodiment, the limiting member 25 has a main body portion 251 which is a plate-shaped member, and divides the combustion space of the combustion chamber 13 into a fire tube side portion 134 and a non-fire tube side portion 133. The burner 12 injects ammonia fuel F2 into the non-fire tube side portion 133, so combustion takes place in the non-fire tube side portion 133. As a result, at least a portion of the flow of the combustion gas G1 generated in the non-fire tube side portion 133 is restricted by the limiting member 25, and it is possible to prevent the combustion gas G1 from flowing into the fire tube 14 without being fully combusted. Furthermore, the space in the non-fire-tube side section 133 where the first fuel F1 and ammonia fuel F2 ejected from the burner 12 are first burned is smaller than the volume of the combustion space in the combustion chamber 13, and the space is restricted. This increases the combustion temperature of the ammonia fuel F2, maintains the combustion gas G1 at a high temperature that promotes combustion, and thus promotes the combustion of the ammonia fuel F2. Therefore, the boiler 20 can reduce the generation of unburned ammonia fuel F2.

[0056] (Third Embodiment) Figure 8 is a diagram illustrating the limiting member 35 of the third embodiment. The boiler 30 of the third embodiment has a similar form to the limiting member 15 of the first embodiment, except that the shape of the limiting member 35 is different. Therefore, parts that perform the same function as in the first embodiment described above are given the same reference numerals or the same reference numerals at the end of the last one or two digits, and redundant explanations are omitted as appropriate. The boiler 30 of the third embodiment includes a drum 11, a burner 12, a combustion chamber 13, a plurality of fire tubes 14, a limiting member 35, and a smoke chamber 16. The boiler 30 also includes an ammonia fuel supply line L200, a first fuel supply line L100, an air supply line L300, a feedwater line L400, an exhaust gas discharge line L500, and a steam supply line L600.

[0057] The limiting member 35 of the third embodiment has a main body portion 351 and a mounting portion 352. The limiting member 35 of the third embodiment is made of the same material as the limiting member 15 of the first embodiment, but the shape of the main body portion 351 is different. The main body portion 351 has a cylindrical member 354 and a plate-shaped member 355. The cylindrical member 354 is a cylindrical member. The plate-shaped member 355 is a semi-cylindrical member that protrudes toward the pipe 14 side, and is provided on the tip side of the cylindrical member 354 (opposite side from the burner 12) and toward the pipe 14 side (upper side in the vertical direction of the drum 11) relative to the central axis C of the cylindrical member 354.

[0058] The mounting portion 352 is cylindrical in shape and is provided with a flange-like portion 353 similar to the flange-like portion 153 of the first embodiment. The mounting portion 352 is adjacent to the cylindrical member 354 of the main body portion 351. In this embodiment, the mounting portion 352 and the main body portion 351 (cylindrical member 354 and plate-like member 355) have the same central axis and diameter and are integrally formed.

[0059] Figure 9 illustrates the flow of combustion gas G1 in the combustion chamber 13 of the boiler 30 according to the third embodiment. In Figure 9, for ease of understanding, a cross-section parallel to the vertical direction passing through the central axis of the burner 12 is shown in and around the combustion chamber 13. The restricting member 35 is positioned in the combustion chamber 13 to divide the combustion chamber 13 into the inside of the cylindrical member 131, the fire tube side portion 134, and the non-fire tube side portion 133. As a result, the restricting member 35 can restrict at least a portion of the flow of combustion gas G1 and suppress the flow of combustion gas G1 containing unburned material into the fire tube 14.

[0060] Furthermore, the burner 12 injects the first fuel F1, ammonia fuel F2, and combustion air A1 into the inside 131 of the cylindrical member, and combustion takes place inside the inside 131 of the cylindrical member, or inside the inside 131 of the cylindrical member and the non-fire-tube side portion 133. The volume of this combustion space is smaller than that of the combustion space of the combustion chamber 13, and as described above, the flow of the combustion gas G1 is restricted, so the boiler 30 can maintain the combustion gas G1 at a high temperature and secure a reaction time at a temperature that promotes combustion.

[0061] Therefore, even when the restricting member 35 is used as in this embodiment, at least a portion of the flow of the combustion gas G1 can be restricted, and the combustion gas G1 can be maintained at a high temperature. Thus, the boiler 30 can promote the combustion of ammonia fuel F2 with the restricting member 35, suppress the generation of unburned ammonia fuel F2, and reduce the amount of unburned material in the exhaust gas.

[0062] According to this embodiment, in addition to the effects described in (1) above, the following effects can be achieved. (7) According to the boiler 30 of this embodiment, the limiting member 35 has a main body 351 comprising a cylindrical member 354 and a plate-shaped member 355, dividing the combustion chamber 13 into the inside of the cylindrical member 131, the fire tube side portion 134, and the non-fire tube side portion 133, and the burner 12 injects ammonia fuel F2 into the inside of the cylindrical member 131, so that combustion takes place inside the cylindrical member 131, or inside the cylindrical member 131 and the non-fire tube side portion 133. As a result, the boiler 30 can maintain a high temperature of the combustion gas G1 inside the cylindrical member 131, promoting the combustion of ammonia fuel F2, and preventing the combustion gas G1 from flowing into the fire tube 14 without being fully burned, thereby suppressing the generation of unburned ammonia fuel F2. As a result, the boiler 30 can reduce the amount of unburned material contained in the exhaust gas.

[0063] In the restricting members 15, 25, and 35 shown in the first to third embodiments described above, the effect of restricting the flow of combustion gas G1 in the combustion space of the combustion chamber 13, ensuring a reaction time at a temperature that promotes the combustion of combustion gas G1, and suppressing the generation of unburned material is highest with the restricting member 15 of the first embodiment, followed by the restricting member 35 of the third embodiment, and then the restricting member 25 of the second embodiment, in that order of decreasing effectiveness. Furthermore, regarding measures to prevent overheating of the restricting members, the restricting member 25 of the second embodiment is the easiest to implement, followed by the restricting member 35 of the third embodiment, and then the restricting member 15 of the first embodiment, in that order of increasing difficulty. Depending on the types of ammonia fuel F2 and first fuel F1, and the ratio of ammonia fuel F2 to first fuel F1, the most suitable restricting member may be selected and used from the first, second, and third embodiments as appropriate.

[0064] (Fourth Embodiment) Figure 10 is a diagram illustrating a composite boiler 1 of the fourth embodiment. The fourth embodiment is a configuration in which the boiler 10 shown in the first embodiment is provided in the composite boiler 1. Therefore, parts that perform the same functions as in the first embodiment described above are given the same reference numerals or the same reference numerals at the end of the last one or two digits, and redundant explanations are omitted as appropriate. The composite boiler 1 is located inside a ship and comprises a boiler 10, a main engine waste heat recovery boiler 60, a drum 41, a feedwater line L400, and a steam supply line L600. The boiler 10 and the main engine waste heat recovery boiler 60 are located inside one drum 41 and share boiler water W2. The boiler 10 and the main engine waste heat recovery boiler 60 also share the steam supply line L600.

[0065] The composite boiler 1 uses a boiler 10 and a main engine waste heat recovery boiler 60 to heat the boiler water W2 in the drum 41 to generate steam, which is then supplied to a steam demand section (not shown) via a steam supply line L600. In this embodiment, the boiler 10 shown in the first embodiment is provided, but the system is not limited to this and may also include the boiler 20 of the second embodiment or the boiler 30 of the third embodiment.

[0066] The main engine waste heat recovery boiler 60 recovers heat from the main engine exhaust gas G2, which is the exhaust gas from the main engine of a ship (not shown), to heat the boiler water W2 and generate steam. The main engine waste heat recovery boiler 60 is located in the same drum 41 as the boiler 10 and includes an inlet smoke chamber 61, a plurality of second fire tubes 62, an outlet smoke chamber 63, a main engine exhaust gas introduction line L700, and a main engine exhaust gas discharge line L800.

[0067] The inlet smoke chamber 61 is located in the lower part of the drum 41, and the main engine exhaust gas introduction line L700 is connected to it. It is the space through which the main engine exhaust gas G2 is introduced. Multiple second smoke tubes 62 are connected to the upper surface of the inlet smoke chamber 61.

[0068] The second fire tube 62 is a fire tube through which the main engine exhaust gas G2 flows. The lower end of the second fire tube 62 is connected to the inlet smoke chamber 61, and the upper end is connected to the outlet smoke chamber 63. Multiple second fire tubes 62 are arranged at predetermined intervals, with their longitudinal direction being the vertical direction of the drum 41, and are located in the boiler water W2. In this embodiment, the longitudinal direction of the second fire tube 62 is parallel to the longitudinal direction of the fire tube 14 on the boiler 10 side.

[0069] The outlet smoke chamber 63 is located at the top of the drum 41 and is the space into which the main engine exhaust gas G2, which has passed through the second flue pipe 62, is introduced. The main engine exhaust gas discharge line L800 is connected to the outlet smoke chamber 63. In addition, multiple second flue pipes 62 are connected to the underside of the outlet smoke chamber 63.

[0070] The main engine exhaust gas introduction line L700 is a line that supplies main engine exhaust gas G2, which is the exhaust gas from the ship's main engine, to the main engine waste heat recovery boiler 60. The main engine exhaust gas discharge line L800 is a line that discharges the main engine exhaust gas G2, which has had its heat recovered in the main engine waste heat recovery boiler 60, to the outside of the system. The discharge port for the main engine exhaust gas G2 of the main engine waste heat recovery boiler 60 (the connection point between the outlet smoke chamber 63 and the main engine exhaust gas discharge line L800) and the exhaust gas discharge port for the boiler 10 (the connection point between the smoke chamber 16 and the exhaust gas discharge line L500) are different and are provided separately. Furthermore, the main engine exhaust gas discharge line L800 and the exhaust gas discharge line L500 have separate discharge ports and do not merge downstream.

[0071] This main engine exhaust heat recovery boiler 60 recovers exhaust heat by circulating the main engine exhaust gas G2 introduced into the inlet smoke chamber 61 through the second fire tube 62 to exchange heat with the boiler water W2, thereby heating the boiler water W2. After heat recovery, the main engine exhaust gas G2 is discharged from the outlet smoke chamber 63 through the main engine exhaust gas discharge line L800 to the outside of the system, etc.

[0072] According to this embodiment, in addition to the effect of (1) above, the following effects can be achieved. (8) The composite boiler 1 of this embodiment includes a boiler 10 equipped with a limiting member 15 in the combustion chamber 13 and a main engine exhaust heat recovery boiler 60. Therefore, the combustion of ammonia fuel F2 can be promoted by changing the flow of combustion gas G1 in the combustion space of the combustion chamber 13 without significantly increasing the size of the combustion chamber 13 and thus increasing the drum diameter, thereby suppressing the generation of unburned ammonia fuel F2. For this reason, the composite boiler 1 incorporates both an auxiliary boiler and an exhaust gas economizer in the same drum, and without compromising the advantages of a composite boiler, which are that it is inexpensive and space-saving compared to installing them separately, while suppressing the generation of unburned ammonia fuel F2.

[0073] (Modified Forms) The present invention is not limited to the embodiments described above, and various modifications and changes are possible, all of which are within the scope of the present invention.

[0074] In each embodiment, the main body portions 151, 251, 351 and the mounting portions 152, 252, 352 may have different diameters. Also, in the third embodiment, the cylindrical member 354 and the plate-shaped member 355 may have different diameters. Furthermore, in each embodiment, the main body portions 151, 251, 351 and the mounting portions 152, 252, 352 may have different central axes, and in the third embodiment, the cylindrical member 354 and the plate-shaped member 355 may have different central axes. The dimensions of each part may be appropriately changed depending on the shape of the burner 12, the shape of the space in which the mounting portions 152, 252, 352 are arranged, etc.

[0075] In the first embodiment, the main body portion 151, which is a cylindrical member, is not limited to a cylindrical shape, but may also be a rectangular tube shape such as a square tube, or an elliptical tube shape, etc. Similarly, the mounting portion 152 may also be a rectangular tube shape or an elliptical tube shape, or for example, the main body portion 151 may be a rectangular tube shape and the mounting portion 152 may be cylindrical. Similarly, in the second embodiment, the main body portion 251, which is a plate-like member, is not limited to a semi-cylindrical shape obtained by cutting a cylindrical shape in half along the central axis direction, but may also be a semi-elliptical tube shape, a semi-square tube shape, or a flat plate shape. Even when the main body portion 251 is a semi-elliptical tube shape or a semi-square tube shape, it is arranged so as to be convex toward the pipe 14 side. Similarly, in the third embodiment, the cylindrical member 354 of the main body portion 351 is not limited to a cylindrical shape, but may also be a rectangular tube shape, an elliptical tube shape, etc. Also, the plate-like member 355 of the main body portion 351 is not limited to a semi-cylindrical shape, but may also be a semi-elliptical tube shape, a semi-square tube shape, or a flat plate shape. Furthermore, the combination of shapes between the cylindrical member 354 and the plate-shaped member 355 may be selected as appropriate.

[0076] Furthermore, in the first embodiment, the end face on the tip side of the main body 151 is shown to be perpendicular to the central axis of the main body 151, but it is not limited to this, and for example, the tip side of the main body 151 may be inclined, that is, the end face on the tip side of the main body 151 may be at an angle α (0° < α < 90°) with respect to the central axis of the main body 151. In this case, it is preferable to position the limiting member 15 in the combustion chamber 13 such that the flue tube 14 side (upper side) of the main body 151 is longer and the non-flue tube side (lower side) is shorter.

[0077] In the fourth embodiment, the composite boiler 1 may be configured to include, in addition to the boiler 10 and the main engine heat recovery boiler 60, an auxiliary engine heat recovery boiler (not shown) for recovering waste heat from an auxiliary engine (generator) located within the drum 41. In this case as well, the exhaust gas after heat exchange in the main engine heat recovery boiler 60 and the exhaust gas after heat exchange in the auxiliary engine heat recovery boiler are not combined. The structure of the auxiliary engine heat recovery boiler is substantially the same as that of the main engine heat recovery boiler, and the exhaust gas discharged from the auxiliary engine (auxiliary engine exhaust gas) is passed through a fire tube (not shown) to recover heat and heat the boiler water W2.

[0078] While each embodiment and its variations can be used in combination as appropriate, a detailed explanation is omitted. Furthermore, the present invention is not limited to the embodiments described above.

[0079] Furthermore, since the present invention promotes the use of ammonia as a fuel that does not emit carbon dioxide, it can contribute, for example, to United Nations Sustainable Development Goal (SDG) 7, "Ensure access to affordable, reliable, sustainable and modern energy."

[0080] 1 Composite boiler 10, 20, 30 Boiler 11, 41 Drum 12 Burner 13 Combustion chamber 131 Inside of cylindrical member 132 Outside of cylindrical member 133 Non-fire tube side 134 Fire tube side 14 Fire tube 15, 25, 35 Restricting member 151, 251, 351 Main body 152, 252, 352 Mounting part 153, 253, 353 Flange part 60 Main engine waste heat recovery boiler

Claims

1. A boiler comprising: a cylindrical drum; a combustion chamber disposed within the drum and having a combustion space; a burner for injecting ammonia fuel containing ammonia into the combustion space; a plurality of flue tubes disposed within the drum and connected to the combustion chamber, through which combustion gas generated by the combustion of the ammonia fuel flows; and a limiting member disposed within the combustion chamber that restricts at least a portion of the flow of the combustion gas toward the flue tubes.

2. The boiler according to claim 1, wherein the limiting member has a main body located in the combustion space that is plate-shaped, and divides the combustion space into a fire-tube side and a non-fire-tube side, and the burner injects the ammonia fuel into the non-fire-tube side.

3. The boiler according to claim 1, wherein the limiting member has a main body located in the combustion space that is a cylindrical member, and the combustion space is divided into the inside of the cylindrical member and the outside of the cylindrical member, and the burner is arranged at one end of the cylindrical member and injects the ammonia fuel into the inside of the cylindrical member.

4. The boiler according to claim 1, wherein the limiting member comprises a main body located in the combustion space, a cylindrical member, and a plate-shaped member extending from the tip of the cylindrical member in the axial direction of the cylindrical member and located on the fire tube side with respect to the central axis of the cylindrical member, the combustion space is divided into an interior of the cylindrical member which is the inside of the cylindrical member, a fire tube side which is on the fire tube side with respect to the main body, and a non-fire tube side which is on the opposite side of the main body from the fire tube side, and the burner is located at the end of the cylindrical member on the side opposite to the plate-shaped member in the axial direction of the cylindrical member, and injects the ammonia fuel into the interior of the cylindrical member.

5. The boiler according to claim 3, wherein the volume of the cylindrical member is 1 / 2 or less of the volume of the combustion space.

6. The boiler according to claim 3, wherein the cylindrical member is cylindrical in shape, and the length of the cylindrical member is one to three times the inner diameter of the cylindrical member.

7. The boiler according to claim 3, wherein the cross-sectional area of ​​the hollow portion of the cylindrical member is less than or equal to the area of ​​the inner surface of the extended portion when the inner surface of the cylindrical member is extended along the axial direction from the tip of the cylindrical member to the inner wall of the combustion chamber.

8. A composite boiler comprising: a boiler according to any one of claims 1 to 7; and a main engine exhaust heat recovery boiler having a plurality of second fire tubes through which main engine exhaust gas flows, wherein the exhaust gas outlet of the boiler and the main engine exhaust gas outlet of the main engine exhaust heat recovery boiler are separately provided.

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