Heat recovery apparatus for high-temperature granular solids and method for recovering heat from high-temperature granular solids

Abstract

To provide a heat recovery apparatus for a high temperature granular solid, using containers made of a material lightweight compared with a refractory, which can more sufficiently suppress heat dissipation from outer walls of the containers to the air.SOLUTION: A heat recovery apparatus 100 for a high temperature granular solid comprises a first container 10, a second container 20 and a gas vent port 30. The first container 10 includes: a first space 12 for storing a high temperature granular solid at the inside; and a cylindrical side part 14 for dividing the first space 12. The second container 20 includes a cylindrical side part 24, and the side part 24 is arranged around the side part 14 of the first container 10 and divides the second space 22 in a space with the side part 14 of the first container 10. The gas vent port 30 is arranged at the inside of the first space 12 and communicates with the second space 22. It is possible that a gas is fed to the second space 22, the gas is fed from the gas vent port 30 into the first space 12 through the second space 22, and the gas is recovered from the first space 12 to execute heat recovery from the high temperature granular solid using the gas.SELECTED DRAWING: Figure 1

Description

Technical Field

[0001] The present invention relates to a heat recovery device and a heat recovery method for recovering heat from high-temperature granular solids such as solidified slag obtained by solidifying steelmaking slag (molten slag) generated in, for example, a steel manufacturing process.

Background Art

[0002] In recent years, for the purpose of reducing CO2 emissions, energy-saving technologies for recovering and utilizing the sensible heat of high-temperature by-products such as molten slag discharged in the steel manufacturing process have become increasingly important. The amount of sensible heat of molten slag depends on its temperature, but is more than 1.5 GJ per ton of slag. If the sensible heat of molten slag can be recovered and effectively utilized, CO2 reduction due to energy saving can be expected.

[0003] As a method for recovering the sensible heat of molten slag, immediately after solidifying the molten slag, the high-temperature solidified slag is charged into a heat recovery tank (container) to form a packed bed, and a normal-temperature gas is blown into the packed bed in the container to take away the heat of the solidified slag in the container and discharge the gas heated to a high temperature from the container for recovery (packed tank method).

[0004] In the design of a heat recovery device for recovering heat from high-temperature granular solids by such a packed bed method, if the granular solids can be charged into the container at as high a temperature as possible, an increase in the recovered heat amount can be expected. For example, since the solidified slag immediately after solidifying steelmaking slag (molten slag) has a high temperature of 1000 °C or higher, it is desirable to charge the solidified slag into the container while maintaining this high-temperature state as much as possible. However, when charging high-temperature granular solids of 1000 °C or higher into the container, the container becomes hot, so the heat dissipated from the outer wall of the container to the atmosphere increases, and as a result, there is a problem that the heat recovery rate is restricted.

[0005] Considering this issue, it is conceivable to construct the inner wall of the container using a refractory material. Since refractory materials have a lower thermal conductivity than metals, the temperature of the outer wall will decrease, and heat dissipation into the atmosphere can be suppressed. However, this would increase the size of the device itself and its support structure, and the increased weight of the device would necessitate strengthening of the foundation structure, resulting in a significant increase in construction costs. Furthermore, frequent loading and unloading of granular solids would cause wear and tear on the refractory material, leading to operational challenges such as reduced operating time due to repairs and increased running costs.

[0006] If the container is constructed from thin sheets such as stainless steel, a significant weight reduction can be achieved, avoiding the aforementioned cost and operational challenges. However, the thermal conductivity of stainless steel is considerably higher than that of refractory materials, and its heat resistance temperature is less than 800°C. Therefore, even when granular solids at temperatures of 1000°C or higher are placed inside the container, a design is needed to keep the temperature of the container's inner wall below the heat resistance temperature of the stainless steel. For example, a water-cooled structure for the container's inner wall could be considered, but when heat exchange is performed using a refrigerant with a large heat capacity like water, the refrigerant temperature hardly increases, so that heat cannot be utilized, resulting in a problem of reduced effective heat recovery rate.

[0007] To address these challenges, Patent Document 1 describes a heat recovery apparatus for high-temperature solidified material, characterized in that it recovers heat by blowing heat recovery gas into a heat recovery tank capable of housing a packed bed of high-temperature solidified material, and is provided with a lower air outlet for supplying heat recovery gas into the heat recovery tank from the lower part of the heat recovery tank, and a refrigerant supply outlet for supplying refrigerant into the heat recovery tank from the inner wall of the heat recovery tank, and a method for recovering heat from high-temperature solidified material, characterized in that high-temperature solidified material is charged into the heat recovery tank, and heat is recovered from the high-temperature solidified material using the heat recovery gas and the refrigerant, respectively. [Prior art documents] [Patent Documents]

[0008] [Patent Document 1] Japanese Patent Publication No. 2019-184122 [Overview of the project] [Problems that the invention aims to solve]

[0009] In Patent Document 1, in addition to blowing heat recovery gas into the heat recovery tank from the lower air outlet, a refrigerant such as gas or water is supplied into the heat recovery tank from a refrigerant supply port provided on the inner wall of the heat recovery tank. The cooling effect of this refrigerant prevents the inner wall from becoming hot and reduces, to some extent, the heat dissipation from the outer wall of the container to the atmosphere. Furthermore, since the heat recovered by the refrigerant, such as the high-temperature gas or water vapor generated when water evaporates, can also be recovered, the decrease in heat recovery rate can be suppressed compared to when the inner wall of the container has a water-cooled structure.

[0010] However, our investigations have revealed that there is room for improvement in reducing heat dissipation from the outer wall of the container to the atmosphere, and from this perspective, there is room to further increase the heat recovery rate.

[0011] Therefore, in view of the above problems, the present invention aims to provide a heat recovery apparatus for high-temperature granular solids and a heat recovery method from high-temperature granular solids that can more sufficiently suppress heat dissipation from the outer wall of a container to the atmosphere by using a container made of a lighter material than refractory material. [Means for solving the problem]

[0012] To solve the above problems, the inventors conceived of a double-walled structure for a heat recovery tank containing high-temperature granular solids, consisting of an inner container and an outer container. High-temperature granular solids are loaded into the inner container, and gas is flowed into the space formed between the outer surface of the inner container and the inner surface of the outer container, and this gas is sent into the inner container. As a result, the heat dissipation from the outer wall of the container (outer container) to the atmosphere can be suppressed more effectively than in the heat recovery device of Patent Document 1. Furthermore, in order to suppress heat dissipation, the gas flowed into the gap between the inner and outer containers is subjected to heat exchange with the high-temperature granular solids in the inner container and is ultimately recovered. Therefore, there is no decrease in the heat recovery rate, as occurs when the inner wall of the container has a water-cooled structure. In other words, the heat recovery rate can be increased compared to the heat recovery device of Patent Document 1 by the amount by which heat dissipation is suppressed more effectively.

[0013] The gist of the present invention is as follows: [1] A first container having a first space inside for containing high-temperature granular solid material and a cylindrical side portion that partitions the first space, A second container having a cylindrical side portion that is positioned around the side portion of the first container and partitions a second space between itself and the side portion of the first container, A gas outlet is located within the first space and communicates with the second space, A heat recovery apparatus for high-temperature granular solids, comprising: a gas supply to the second space; the gas being sent from the gas outlet to the first space via the second space; and the gas being recovered from the first space, thereby enabling heat recovery from the high-temperature granular solids using the gas.

[0014] [2] The gas outlet is located at the bottom of the first space, A gas supply pipe connected to the upper part of the side of the second container and having a flow path communicating with the second space, A connecting pipe is disposed within the first space, with one end connected to the lower part of the side of the first container and the other end connected to the gas outlet, and having a flow path that connects the second space and the gas outlet. A gas discharge pipe connected to the upper part of the side of the first container and having a flow path communicating with the first space, The heat recovery device for high-temperature granular solids according to [1] above, which has

[0015] [3] It has a blower connected to the gas supply pipe, The blower is configured to be able to supply at least one selected from the group consisting of air, nitrogen, carbon dioxide, and water vapor as the gas into the second space through the gas supply pipe. The heat recovery device for high-temperature granular solids according to [2] above.

[0016] [4] The blower is able to supply one or both of carbon dioxide and water vapor as the gas into the second space through the gas supply pipe, In addition to the heat recovery, it is configured to be able to carry out the reaction between the high-temperature granular solids and the gas. The heat recovery device for high-temperature granular solids according to [3] above.

[0017] [5] It has a mist generator connected to the gas supply pipe, The mist generator is able to supply water droplets into the second space through the gas supply pipe, In addition to the heat recovery, it is configured to be able to carry out the reaction between the high-temperature granular solids and the gas. The heat recovery device for high-temperature granular solids according to [3] or [4] above.

[0018] [6] A heat exchanger connected to the gas discharge pipe and cooling the gas recovered from the first space through the gas discharge pipe, A gas pipe connecting the heat exchanger and the blower and supplying the gas cooled by the heat exchanger to the blower, The heat recovery device for high-temperature granular solids according to any one of [3] to [5] above, which has

[0019] [7] The heat recovery device for high-temperature granular solids according to any one of [2] to [6] above, in which a rectifying plate for controlling the flow of the gas is arranged in the second space.

[0020] [8] The rectifying plates are arranged with a spacing in the vertical direction such that their main surfaces are along the circumferential direction of the first container and the second container, and n plates (where n is an integer of 1 or more) are arranged at intervals in the vertical direction. The second space is divided into (n + 1) layers in the vertical direction by the n rectifying plates. For each of the rectifying plates, there is an opening provided to communicate the layers adjacent to each other in the vertical direction through the rectifying plate, in the high-temperature granular solid heat recovery device described in [7] above.

[0021] [9] n is an integer of 2 or more. Among the n rectifying plates, the openings in two rectifying plates adjacent to each other in the vertical direction are located on opposite sides in the circumferential direction of the first container and the second container, in the high-temperature granular solid heat recovery device described in [8] above.

[0022]

[10] n is 3, in the high-temperature granular solid heat recovery device described in [9] above.

[0023]

[11] The connection part of the communication pipe with the side part of the first container is located below the lowermost rectifying plate among the n rectifying plates. The opening of the lowermost rectifying plate and the connection part are located on opposite sides in the circumferential direction of the first container and the second container, in the high-temperature granular solid heat recovery device according to any one of [8] to

[10] above.

[0024]

[12] The connection part of the gas supply pipe with the side part of the second container is located above the uppermost rectifying plate among the n rectifying plates. The opening of the uppermost rectifying plate and the connection part are located on opposite sides in the circumferential direction of the first container and the second container, in the high-temperature granular solid heat recovery device according to any one of [8] to

[11] above.

[0025]

[13] A heat recovery method from high-temperature granular solids, which uses the high-temperature granular solid heat recovery device according to any one of [1] to

[12] above to recover heat from the high-temperature granular solids by the gas.

[0026]

[14] The method for recovering heat from high-temperature granular solids according to

[13] above, wherein the high-temperature granular solid is steel slag.

[0027]

[15] The method for recovering heat from high-temperature granular solids according to

[14] above, wherein the steel slag is steelmaking slag.

[0028]

[16] A method for recovering heat from high-temperature granular solids according to any one of the above

[13] to

[15] , wherein the gas contains carbon dioxide and water vapor, or both, and in addition to the heat recovery, a reaction is carried out between the high-temperature granular solids and the gas. [Effects of the Invention]

[0029] According to the heat recovery apparatus and heat recovery method for high-temperature granular solids of the present invention, it is possible to more effectively suppress heat dissipation from the outer wall of the container to the atmosphere by using a container made of a lighter material than refractory material. [Brief explanation of the drawing]

[0030] [Figure 1] This is a schematic diagram illustrating the gas flow in a heat recovery device according to each embodiment of the present invention. [Figure 2] This is a schematic diagram showing the configuration of a heat recovery device 100 according to a first embodiment of the present invention. [Figure 3] This is a schematic diagram showing the configuration of a heat recovery device 200 according to a second embodiment of the present invention. [Figure 4] This is a schematic diagram showing the configuration of a heat recovery device 300 according to a third embodiment of the present invention. [Figure 5] This is a schematic diagram showing the configuration of a heat recovery device 400 according to a fourth embodiment of the present invention. [Figure 6] Figure 5 is a top view of the heat recovery device 400. [Modes for carrying out the invention]

[0031] Hereinafter, with reference to Figures 1 to 6, the heat recovery devices 100, 200, 300, and 400 for high-temperature granular solids according to the first to fourth embodiments of the present invention will be described. First, with reference to Figure 1, the heat recovery devices 100, 200, 300, and 400 for high-temperature granular solids according to each embodiment of the present invention have as common main components a first container (inner container) 10, a second container (outer container) 20, a gas outlet 30, a gas supply pipe 40, a connecting pipe 50, and a gas discharge pipe 60. The first container 10 has a first space 12 for containing high-temperature granular solids inside, and has a cylindrical side portion 14 that partitions this first space 12. The second container 20 has a cylindrical side portion 24, which is arranged around the side portion 14 of the first container 10 and partitions a second space 22 between it and the side portion 14 of the first container 10. The gas outlet 30 is located within the first space 12 and communicates with the second space 22 via a connecting pipe 50. The heat recovery devices 100, 200, 300, and 400 are configured to recover heat from high-temperature granular solids by supplying gas from the gas supply pipe 40 to the second space 22, sending the gas through the second space 22 to the first space 12 from the gas outlet 30, and recovering the gas from the first space 12 via the gas discharge pipe 60.

[0032] Furthermore, the heat recovery method from high-temperature granular solids according to each embodiment of the present invention involves using the high-temperature granular solid heat recovery devices 100, 200, 300, and 400 to recover heat from the high-temperature granular solids using the aforementioned gas.

[0033] The high-temperature granular solid is not particularly limited, but steel slag is a preferred example. The steel slag may be steelmaking slag or blast furnace slag. The steelmaking slag may be converter slag or electric furnace slag. The blast furnace slag may be slowly cooled slag or water-granulated slag. Below, the configuration of the heat recovery apparatus according to each embodiment will be described using the case where steelmaking slag immediately after solidification is used as the high-temperature granular solid as an example.

[0034] The type of gas supplied to the second space 22 and ultimately discharged and recovered from the first space 12 is not particularly limited, but can be at least one selected from the group consisting of air, nitrogen, carbon dioxide, and water vapor. These gases can be used to recover heat from high-temperature particulate solids.

[0035] The type of gas is preferably carbon dioxide and / or water vapor. In this case, in addition to heat recovery, a reaction can be carried out between the steelmaking slag as a high-temperature granular solid and these types of gases, as described below. In this case, the heat recovery apparatus for high-temperature granular solids according to this embodiment also serves as a reaction apparatus between the high-temperature granular solid and the gas, and the heat recovery method from high-temperature granular solids according to this embodiment also serves as a reaction method between the high-temperature granular solid and the gas.

[0036] If the gas contains water vapor, steam aging treatment can be performed on steelmaking slag. Steam aging is a process in which water vapor is supplied to high-temperature steelmaking slag, and the free lime (free-CaO) contained in the slag is hydrated by the following equation (1) as the main reaction. The slag thus obtained after treatment has undergone the expansion reaction through steam aging and can be shipped as steel slag for roads. CaO + H2O → Ca(OH)2···(1)

[0037] If the gas contains carbon dioxide, the steelmaking slag can be subjected to carbonation treatment. Carbonation treatment is a process in which carbon dioxide (CO2) is supplied to high-temperature steelmaking slag, and the free lime (free-CaO) contained in the slag is carbonated, with the following equation (2) being the main reaction. The slag thus obtained after treatment has undergone the expansion reaction due to the carbonation treatment and can be shipped as steel slag for roads. CaO + CO2 → CaCO3···(2)

[0038] Referring to Figure 1, the gas flow, gas temperature change, and steelmaking slag temperature change in each embodiment will be explained. In Figure 1, arrows other than the leader lines of the symbols (including block arrows) indicate the gas flow. The same applies to Figures 2-4 and 6. The arrows indicating the gas flow consist of three types: dotted, dashed, and solid lines, indicating that the gas temperature increases in this order.

[0039] First, the steelmaking slag immediately after solidification is charged into the first container 10 to form a packed layer. The temperature of the steelmaking slag at the stage when it is charged into the first container 10 is preferably as high as possible, and preferably 1000°C or higher.

[0040] The temperature of the gas supplied to the second space 22 via the gas supply pipe 40 is not particularly limited as long as it is sufficiently lower than the temperature of the steelmaking slag when it is charged into the inner container 10, but is preferably room temperature (10 to 35°C). The gas introduced into the second space 22 can efficiently cool the first container 10, which receives heat input from the high-temperature packed bed due to radiant heat, and becomes hot in the process. In addition, mist-like water may be added to the gas supplied to the second space 22 via the gas supply pipe 40. Mist-like water also contributes greatly to the cooling of the first container 10, and becomes hot and turns into water vapor.

[0041] The gas in the second space 22 is introduced into the first space 12 from the gas outlet 30 via the connecting pipe 50. The gas temperature at this stage depends on the size of the first container 10 and the second container 20 and the gas flow rate, but is preferably around 100 to 200°C. If mist-like water is added to the gas supplied to the second space 22, the mist-like water will have turned into water vapor at this stage. The temperature of the gas introduced into the first space 12 being 100°C or higher is required in order to efficiently perform steam aging treatment on the steelmaking slag in the first container 10. The reaction rate of the carbonation treatment is also higher at higher gas temperatures, so from this viewpoint as well, it is preferable that the temperature of the gas introduced into the first space 12 be 100°C or higher.

[0042] The gas introduced into the first space 12 is subjected to direct heat exchange with the high-temperature packed bed, further increasing in temperature, and is then discharged from the first space 12 via the gas discharge pipe 60 and recovered. In this embodiment, efficient heat exchange can be achieved, so the temperature of the gas discharged from the first space 12 can be set to about 1000°C, which is close to the temperature of the steelmaking slag at the stage when it is charged into the first container 10. As a result of heat exchange with the gas, the steelmaking slag is cooled to about 100°C or below.

[0043] According to each embodiment of the present invention, the first container 10 can be efficiently cooled by the gas introduced into the second space 22, thereby sufficiently suppressing heat dissipation from the outer wall of the second container 20 to the atmosphere. Furthermore, the gas introduced into the second space 22 moves to the first space 12, where it is used for heat exchange with the steelmaking slag and is ultimately recovered. Therefore, there is no decrease in heat recovery rate, as can occur when the inner wall of the container has a water-cooled structure. In other words, the heat recovery rate can be increased compared to the heat recovery device of Patent Document 1 by the amount by which heat dissipation is further suppressed.

[0044] The configuration of the heat recovery device 100 according to the first embodiment of the present invention will be described in detail below with reference to Figure 2.

[0045] The first container 10 has a first space 12 for containing steelmaking slag inside, and a cylindrical side portion 14 that partitions this first space 12. The second container 20 has a cylindrical side portion 24, which is arranged around the side portion 14 of the first container 10 and partitions a second space 22 between it and the side portion 14 of the first container 10. From the viewpoint of uniform heat recovery and reaction, it is preferable that the side portion 14 of the first container 10 and the side portion 24 of the second container 20 are both cylindrical in shape, and that the cylindrical axes are coaxial and coincide with the vertical direction. That is, in this specification, "up and down direction" means the vertically upward direction and the vertically downward direction.

[0046] The upper part 16 and lower part 18 of the first container 10 are not shown in detail, but the lower part 18 has an openable and closable structure. It is closed when steelmaking slag is charged and during heat recovery (and reaction), and opened when the steelmaking slag is discharged from the first container 10 after heat recovery (and reaction). The upper part 16 also has an openable and closable structure. It is open when steelmaking slag is charged and closed during heat recovery (and reaction) and when the steelmaking slag is discharged.

[0047] The upper 26 and lower 28 of the second container 20 are not shown in detail, but the lower 28 is always closed to partition the second space 22. The upper 26, like the upper 16, has an openable and closable structure, and is opened when steelmaking slag is charged, and closed during heat recovery (and reaction) and when steelmaking slag is discharged.

[0048] The inner diameter of the first container 10 is not particularly limited, but can be in the range of 100 to 10,000 mm. The difference between the inner diameter of the second container 20 and the outer diameter of the first container 10, i.e., the width of the second space 22, is not particularly limited, but can be in the range of 10 to 1,000 mm. The height of the packed layer of steelmaking slag (high-temperature granular solid) inside the first container 10 is preferably in the range of 100 to 50,000 mm, and the heights of the sides 14 of the first container 10 and the sides 24 of the second container 20 should be sufficient to achieve the above packed layer height, for example, in the range of 100 to 60,000 mm.

[0049] The sides 14 of the first container 10 and the sides 24 of the second container 20, i.e., the walls, are preferably made of stainless steel plates without using refractory materials, and among these, SUS310S steel plates, which have relatively good heat resistance, are preferred. By using stainless steel plates that are thinner than refractory materials in this way, a significant weight reduction can be achieved, and cost and operational issues can be avoided. In this embodiment, since the first container 10 can be efficiently cooled by the gas introduced into the second space 22, even if steelmaking slag at a high temperature of 1000°C or more is charged into the first container 10, the temperature of the inner wall of the first container 10 can be kept below the heat resistance temperature of the stainless steel plate without employing a water cooling structure.

[0050] Generally, when circulating gas through the packed bed inside a container, the gas is supplied from the bottom of the container, for example, as in a coke dry fire extinguishing system. From this viewpoint, it is preferable that the gas outlet 30 be located in the lower part of the first space 12. The "lower part" of the first space 12 is defined as the space from the bottom 25% in the height direction of the first space 12, which is partitioned by the side portion 14 of the first container 10. The "upper part" of the first space 12 is defined as the space from the top 25% in the height direction of the first space 12. Furthermore, from the viewpoint of achieving uniform airflow, it is preferable that the gas outlet 30 be located in the center of the first space 12 when viewed from above. The gas outlet 30 has a cylindrical body 32 and a conical upper part 34 connected to the upper part of the cylindrical body 32, and there is a slit (not shown) in the lower part of the conical upper part 34 that protrudes from the cylindrical body 32, and gas is ejected from this slit.

[0051] The gas supply pipe 40 has a connection part 44 at one end that is connected to the upper part of the side 24 of the second container 20, and has a flow path 42 that communicates with the second space 22, and the other end is connected to the blower 70. The "upper part" of the side 24 of the second container 20 is defined as the top 25% of the side 24 in the height direction. The "lower part" of the side 24 of the second container 20 is defined as the bottom 25% of the side 24 in the height direction.

[0052] The connecting pipe 50 is positioned within the first space 12, with one end being a connecting portion 52 connected to the lower part of the side portion 14 of the first container 10, and the other end being a connecting portion 54 connected to the cylindrical body 32 of the gas outlet 30. The connecting pipe 50 has a flow path 56 that connects the second space 22 and the gas outlet 30. That is, the flow path 56 communicates with the second space 22 and also with the inside of the cylindrical body 32. Therefore, the gas in the second space 22 moves into the inside of the cylindrical body 32 via this connecting pipe 50 and is injected into the first space 12 from the slit (not shown) of the gas outlet 30 (see Figure 1). The "lower part" of the side portion 14 of the first container 10 is defined as the bottom 25% of the side portion 14 in the height direction.

[0053] The gas discharge pipe 60 has a connection portion 64 at one end that is connected to the upper part of the side portion 14 of the first container 10, and has a flow path 62 that communicates with the first space 12. The "upper part" of the side portion 14 of the first container 10 is defined as the top 25% of the side portion 14 in the height direction. In Figure 2, the connection portion 44 of the gas supply pipe 40 and the connection portion 64 of the gas discharge pipe 60 are located on opposite sides of the first container 10 and the second container 20 in the circumferential direction, but the positional relationship between the two is not particularly limited.

[0054] The blower 70 is connected to the gas supply pipe 40. The blower 70 is configured to supply at least one gas selected from the group consisting of air, nitrogen, carbon dioxide, and water vapor to the second space 22 via the gas supply pipe 40. That is, the blower 70 is connected to a gas supply mechanism (not shown) for supplying the blower 70 with the desired type of gas.

[0055] According to this embodiment, the gas supplied from the gas supply pipe 40 to the second space 22 moves from top to bottom through the second space 22, is sent to the first space 12 from the gas outlet 30 via the connecting pipe 50, moves from bottom to top through the first space 12, and is discharged from the top of the first space 12 via the gas discharge pipe 60 and recovered. During this process, it is possible to recover heat from the steelmaking slag using the gas. Furthermore, if the gas is carbon dioxide and / or water vapor, in addition to heat recovery, it is possible to perform a reaction between the steelmaking slag and the gas (one or both of a carbonation treatment and / or a steam aging treatment).

[0056] According to this embodiment, the following effects can also be achieved. Generally, when gas is circulated in a packed bed, the porosity tends to be higher near the inner wall of the container than in the center of the container, so the gas tends to flow near the inner wall. As in Patent Document 1, when gas (refrigerant) is injected from the inner wall of the container toward the packed bed, that gas also tends to flow near the inner wall.

[0057] Therefore, under normal circumstances, a large amount of gas flows near the inner wall, and the temperature of the steelmaking slag near the inner wall tends to decrease. However, in Patent Document 1, this tendency becomes more pronounced due to gas injection from the inner wall. As a result, the temperature of the steelmaking slag near the inner wall decreases significantly compared to other areas.

[0058] In this case, the gas injected from the inner wall passes near the inner wall, resulting in heat exchange with the low-temperature steelmaking slag. As a result, the gas temperature does not rise sufficiently before passing through the packed bed, lowering the average temperature of the recovered gas. Therefore, even if the total amount of heat recovered remains the same, the exergy of the recovered heat decreases. Furthermore, when steelmaking slag reacts with gas, the reaction rate is generally highly temperature-dependent. If the reaction conditions are controlled based on regions other than near the inner wall, the reaction rate decreases near the inner wall where the temperature is lower. For example, when performing steam aging or carbonation treatments on steelmaking slag, processing defects are likely to occur in the steelmaking slag near the inner wall, posing a risk of the product being unsuitable for shipment. Thus, the heat recovery apparatus described in Patent Document 1 cannot be considered an ideal method from the viewpoint of heat recovery or reactivity.

[0059] In contrast, according to this embodiment, the gas supplied from the gas supply pipe 40 to the second space 22 is not supplied directly into the first space 12 from the side 14 of the first container 10, but rather supplied into the first space 12 via the connecting pipe 50 from the air outlet 30 located at the bottom of the first space 12. As a result, the temperature of the steelmaking slag in the first space 12 is less likely to be uneven between the vicinity of the inner wall and other areas. Therefore, with regard to heat recovery, not only is the total amount of heat recovered not reduced, but the exergy of the recovered heat is also not reduced. Furthermore, with regard to the reaction, the reaction rate near the inner wall is not reduced, so it is possible to suppress processing defects of the steelmaking slag near the inner wall.

[0060] The flow rate of the gas supplied from the gas supply port 40 to the second space 22 should be set appropriately according to the size of the first container 10 and the second container 20 so that appropriate heat recovery (and reaction) can be performed, and is not particularly limited, but for example, 10 to 10,000 Nm³ 3It can be within the range of / hr. The empty gas velocity in the first space 12 can also be set appropriately according to the size of the first container 10 and the second container 20 so that appropriate heat recovery (and reaction) is carried out, and is not particularly limited, but can be in the range of 0.001 to 10 m / s, for example.

[0061] Referring to Figure 2, it is preferable that a flow straightening plate 80 for controlling the gas flow is arranged in the second space 22. Preferably, n flow straightening plates 80 (where n is an integer of 1 or more) are arranged with spacing in the vertical direction so that their main surfaces are aligned with the circumferential direction of the first container 10 and the second container 20, and these n flow straightening plates 80 divide the second space 22 into (n+1) layers in the vertical direction. Figure 2 shows an example in which three flow straightening plates, a first flow straightening plate 80A, a second flow straightening plate 80B, and a third flow straightening plate 80C, are arranged with spacing in the vertical direction from top to bottom, and these three flow straightening plates 80A, 80B, and 80C divide the second space 22 into four layers from top to bottom: the first layer 22A, the second layer 22B, the third layer 22C, and the fourth layer 22D. When multiple flow straightening plates are provided, they can be arranged at equal intervals in the vertical direction.

[0062] Each of the rectifier plates 80 is provided with an opening 82 that connects adjacent floors in the vertical direction via the rectifier plate 80. In Figure 2, the opening 82A of the first rectifier plate 80A connects the first floor 22A and the second floor 22B, which are adjacent in the vertical direction via the first rectifier plate 80A. The opening 82B of the second rectifier plate 80B connects the second floor 22B and the third floor 22C, which are adjacent in the vertical direction via the second rectifier plate 80B. The opening 82C of the third rectifier plate 80C connects the third floor 22C and the fourth floor 22D, which are adjacent in the vertical direction via the third rectifier plate 80C. The size of the opening 82 is not particularly limited and can be appropriately determined from the viewpoint of not hindering the purpose of the rectifier plate 80, which is to divide the second space 22, and appropriately connecting adjacent floors.

[0063] The rectifier plate 80, which has an opening in part of a ring-shaped plate, allows gas to pass uniformly through the entire second space 22, enabling more efficient heat exchange with the side 14 of the first container 10. In addition, since the rectifier plate 80 joins a part of the first container 10 and the second container 20, it also has a reinforcing effect on these containers, improving their durability.

[0064] When n is an integer greater than or equal to 2, it is preferable that the openings of two vertically adjacent rectifier plates among the n rectifier plates are located on opposite sides of the circumferential direction of the first container 10 and the second container 20. In Figure 2, the openings 82A and 82B of the vertically adjacent first rectifier plate 80A and second rectifier plate 80B are located on opposite sides of the circumferential direction of the first container 10 and the second container 20. Similarly, the openings 82B and 82C of the vertically adjacent second rectifier plate 80B and third rectifier plate 80C are located on opposite sides of the circumferential direction of the first container 10 and the second container 20. By alternating the positions of the openings in this way, a gas flow as shown in Figure 1 can be achieved, and the gas can pass more uniformly through the entire second space 22. As a result, heat exchange with the side portion 14 of the first container 10 can be performed more efficiently.

[0065] The number of rectifier plates 80 should be appropriately determined according to the size (especially the height) of the first container 10 and the second container 20. If there are too many rectifier plates, heat will escape through the plates. The number of rectifier plates 80 can be, for example, 1 to 5, preferably 2 to 4, and more preferably 3.

[0066] As shown in Figure 2, the connection portion 52 of the connecting pipe 50 to the side portion 14 of the first container 10 is located below the lowest rectifier plate (third rectifier plate 80C in Figure 2). Preferably, the opening 82C of the lowest rectifier plate 80C and the connection portion 52 are located on opposite sides of the circumferential direction of the first container 10 and the second container 20. This makes it possible to achieve the gas flow shown in Figure 1, and allows the gas to pass more uniformly through the lowest layer (fourth layer 22D) of the second space 22.

[0067] As shown in Figure 2, the connection portion 44 of the gas supply pipe 40 to the side portion 24 of the second container 20 is located above the uppermost rectifier plate (first rectifier plate 80A in Figure 2). Preferably, the opening 82A of the uppermost rectifier plate 80A and the connection portion 44 are located on opposite sides of the circumferential direction of the first container 10 and the second container 20. This makes it possible to achieve the gas flow shown in Figure 1, and allows the gas to pass more uniformly through the uppermost layer (first layer 22A) of the second space 22.

[0068] Referring to Figure 3, the configuration of the heat recovery device 200 according to the second embodiment of the present invention will be described. The heat recovery device 200 has a configuration that adds a mist generator 72 and a blower 73 to the heat recovery device 100 according to the first embodiment. Therefore, the configuration other than the mist generator 72 and the blower 73 will be described by reference to the description in the first embodiment.

[0069] The mist generator 72 is connected to the gas supply pipe 40 downstream of the main blower 70, and can supply water droplets to the second space 22 via the gas supply pipe 40. The blower 73 is connected to the mist generator 72. By operating the blower 73, water droplets generated from the mist generator 72 are supplied to the gas supply pipe 40. As a result, water droplets can be mixed into the gas supplied from the main blower 70. As the water droplets pass through the second space 22, they become hot through heat exchange with the side 14 of the first container 10 and turn into steam. The steam thus generated is supplied to the first space 12 from the gas outlet 30 via the connecting pipe 50. Therefore, in addition to heat recovery, a reaction between steelmaking slag and steam (i.e., steam aging treatment) can be performed.

[0070] Referring to Figure 4, the configuration of the heat recovery device 300 according to the third embodiment of the present invention will be described. The heat recovery device 300 has a configuration that adds a heat exchanger 74, a heat exchange gas blower 76, and gas piping 78 to the heat recovery device 100 according to the first embodiment. Therefore, the description of the other components will be based on the description in the first embodiment.

[0071] The heat exchanger 74 is connected to the gas exhaust pipe 60 and cools the high-temperature gas recovered from the first space 12 via the gas exhaust pipe 60. Specifically, room-temperature gas is supplied to the heat exchanger 74 from a heat exchange gas blower 76 connected to the heat exchanger 74, where the high-temperature gas is cooled. The gas piping 78 connects the heat exchanger 74 and the blower 70 and supplies the gas cooled in the heat exchanger 74 to the blower 70. This allows the gas cooled in the heat exchanger 74 to be supplied again to the second space 22 from the gas supply pipe 40 by the blower 70.

[0072] The type of heat exchanger 74 is selected according to the temperature of the gas recovered from the first space 12. If the recovered gas contains water vapor, it is preferable to provide a condenser or gas-liquid separator on the outlet side of the heat exchanger 74. Alternatively, heat exchange may be performed until the temperature at which water vapor condensation does not occur, and the gas may be recycled and reused as gas to be blown back into the packed bed. The separated water can be reused as a spray mist.

[0073] Referring to Figures 5 and 6, the configuration of the heat recovery device 400 according to the fourth embodiment of the present invention will be described. The heat recovery device 400 is the same as the heat recovery device 100 of the first embodiment, except that it has two gas supply pipes, a first gas supply pipe 40A and a second gas supply pipe 40B. Therefore, the description of the configuration other than the gas supply pipes will be based on the description of the first embodiment.

[0074] In this embodiment, the connection portion 44A of the first gas supply pipe 40A to the side portion 24 of the second container 20 and the connection portion 44B of the second gas supply pipe 40B to the side portion 24 of the second container 20 are located on opposite sides of the first container 10 and the second container 20 in the circumferential direction. The connection portion 64 of the gas discharge pipe 60 is located 90 degrees offset from the connection portions 44A and 44B in the circumferential direction of the first container 10 and the second container 20. As shown in Figure 6, the first gas supply pipe 40A, the second gas supply pipe 40B, and the gas discharge pipe 60 are located on the same side when the first container 10 and the second container 20 are divided into two along the axis. In this case, the airflow supplied from the first gas supply pipe 40A and the airflow supplied from the second gas supply pipe 40B collide in the first layer 22A of the second space 22, and then reverse direction and move towards the gas discharge pipe 60. Even with this type of gas flow, the gas can pass uniformly through the first layer 22.

[0075] Furthermore, two or more combinations selected from the second to fourth embodiments also suitably constitute the present invention.

[0076] Furthermore, although a single gas flow path is formed within the second space 22 in Figures 1-6, additional structures may be provided within the second space 22 to create multiple flow paths. [Examples]

[0077] An experiment was conducted to recover heat and perform carbonation treatment by charging steelmaking slag, a high-temperature granular solid at 1000°C, into a reaction vessel. 4 tons of steelmaking slag were used. The temperature of the steelmaking slag upon charging the vessel was 900°C. CO2 was used as the supply gas, with a flow rate of 1100 Nm³. 3 The time was set to / hr. The ambient temperature and supply gas temperature were 20°C. The inner diameter of the inner container was 1.4m, and the packed bed height was 1.37m. The above specifications are common to Comparative Examples 1 and 2 and Invention Examples 1 and 2.

[0078] In Comparative Example 1, a reaction vessel was used that did not have a double-walled structure consisting only of an inner container. The thickness of the side wall of the inner container was 10 mm, and the material of the side wall was SUS310S.

[0079] In Comparative Example 2, a reaction vessel was used that was not a double-walled structure with only an inner container, similar to Comparative Example 1, and CO2 gas was supplied as a refrigerant from the side wall of the inner container toward the packed bed, similar to Patent Document 1. The temperature of the refrigerant gas was 20°C, and the flow rate was 110 Nm³. 3 I set it to / hr.

[0080] In Invention Example 1, a double-walled reaction vessel similar to that shown in Figure 2 was used, except that it lacked a rectifier plate. The thickness of the side walls of the inner container was 10 mm, the thickness of the side walls of the outer container was 10 mm, and the gap flow path between the inner and outer walls was 10 mm. The material for the side walls of the inner and outer containers was SUS310S.

[0081] In Invention Example 2, three rectifier plates were added to Invention Example 1, and a double-walled reaction vessel as shown in Figure 2 was used.

[0082] Table 1 shows the results of the reaction and heat recovery tests conducted between steelmaking slag and CO2 in each example.

[0083] In Comparative Example 1, the radiant heat from the steelmaking slag caused the container walls to become very hot, resulting in a large amount of heat being released into the atmosphere.

[0084] In Comparative Example 2, the container walls were cooled by flowing the refrigerant gas, but the steelmaking slag was also cooled. As a result, heat dissipation was suppressed, the amount of carbonation decreased, and the recovered gas temperature also decreased.

[0085] In Invention Example 1, the cooling effect of the gas flowing through the gap channel suppresses the temperature of the inner wall. Furthermore, since the outer wall, which is in contact with the atmosphere, receives heat only from the gas in the gap channel, the amount of heat input from the high-temperature steelmaking slag is significantly reduced, and as a result, the amount of heat dissipated to the atmosphere is greatly reduced. In addition, the gas temperature at the supply port to the packed bed increased, which also increased the amount of carbonation reaction of the steelmaking slag.

[0086] In Invention Example 2, the action of the rectifier plate increased the time that the gas flowing through the gap channel remained in the gap channel, and the amount of heat exchange with the inner wall increased. As a result, the inner wall temperature was suppressed. On the other hand, the amount of heat exchange with the outer wall also increased, so the amount of heat dissipation also increased. The amount of carbonation reaction of the steelmaking slag was the same as in Invention Example 1.

[0087] The heat recovery rate is calculated by subtracting the heat loss from the heat contained in the steelmaking slag (3.5 GJ). In Comparative Example 1, approximately 85% was recovered; in Comparative Example 2, approximately 93%; and in Invention Examples 1 and 2, approximately 98%. Regarding the gas temperature during recovery, as the steelmaking slag temperature gradually decreases, it was initially close to 900°C, but decreased over time.

[0088] [Table 1] [Industrial applicability]

[0089] According to the heat recovery apparatus and heat recovery method for high-temperature granular solids of the present invention, it is possible to more effectively suppress heat dissipation from the outer wall of the container to the atmosphere by using a container made of a lighter material than refractory material. [Explanation of Symbols]

[0090] 100 Heat recovery system 200 Heat Recovery System 300 Heat Recovery System 400 Heat Recovery System 10 First container (inner container) 12 1st space 14. Cylindrical side 16 Top 18 Lower 20 Second container (outer container) 22 Second space 22A 1st layer 22B 2nd layer 22C 3rd layer 22D 4th layer 24 Cylindrical side 26 Top 28 Lower part 30 Gas vents 32 Cylindrical body 34 Conical upper part 40 Gas supply pipe 42 Flow channels 44 Connection part with the side of the second container 40A First gas supply pipe 44A Connection part with the side of the second container 40B Second gas supply pipe 44B Connection part with the side of the second container 50 Communication pipe 52 Connection part (one end) to the side of the first container 54 Connection to the gas outlet (other end) 56 channels 60 Gas exhaust pipe 62 channels 64 Connection part with the side of the first container 70 Blower 72 Mist Generator 73 Blower 74 Heat exchanger 76 Heat exchange gas blower 78 Gas piping 80 Rectifier plate 82 Opening 80A First rectifier plate (uppermost rectifier plate) 82A opening 80B 2nd rectifier plate 82B opening 80C Third rectifier plate (lowest rectifier plate) 82C opening

Claims

1. A first container having a first space inside for containing high-temperature granular solid material, and having cylindrical sides that partition the first space, A second container having a cylindrical side portion that is positioned around the side portion of the first container and partitions a second space between itself and the side portion of the first container, A gas outlet located at the lower part of the first space and communicating with the second space, A gas supply pipe connected to the upper part of the side of the second container and having a flow path communicating with the second space, A connecting pipe is disposed within the first space, with one end connected to the lower part of the side of the first container and the other end connected to the gas outlet, and having a flow path that connects the second space and the gas outlet. A gas discharge pipe connected to the upper part of the side of the first container and having a flow path communicating with the first space, A heat recovery apparatus for high-temperature granular solids, comprising: a gas supply pipe, a gas supply pipe, a gas supply pipe, a gas supply pipe, a gas supply pipe, a gas supply pipe, and a gas discharge pipe, wherein the gas is recovered from the first space via the gas discharge pipe, thereby enabling heat recovery from the high-temperature granular solids using the gas.

2. Having a blower connected to the gas supply pipe, The heat recovery apparatus for high-temperature granular solids according to claim 1, wherein the blower is configured to supply at least one selected from the group consisting of air, nitrogen, carbon dioxide, and water vapor as the gas to the second space via the gas supply pipe.

3. The blower is capable of supplying carbon dioxide and / or water vapor as the gas to the second space via the gas supply pipe. The heat recovery apparatus for high-temperature granular solids according to claim 2, configured to allow for the reaction of the high-temperature granular solids with the gas, in addition to the heat recovery described above.

4. It has a mist generator connected to the gas supply pipe, The mist generator is capable of supplying water droplets to the second space via the gas supply pipe. A heat recovery apparatus for high-temperature granular solids according to claim 2 or 3, configured to allow a reaction between the high-temperature granular solids and the gas, in addition to the heat recovery described above.

5. A heat exchanger connected to the gas discharge pipe and used to cool the gas recovered from the first space via the gas discharge pipe, A gas piping connects the heat exchanger and the blower, and supplies the gas cooled by the heat exchanger to the blower. A heat recovery apparatus for high-temperature granular solids according to claim 2 or 3, comprising the above.

6. The heat recovery apparatus for high-temperature granular solids according to claim 1, wherein a flow straightening plate for controlling the flow of the gas is arranged in the second space.

7. The rectifier plates are arranged in a number of n (where n is an integer of 1 or more) with spacing between them in the vertical direction, such that their main surfaces are aligned with the circumferential direction of the first and second containers. The n rectifier plates divide the second space into (n+1) layers in the vertical direction. The heat recovery apparatus for high-temperature granular solids according to claim 6, wherein each of the rectifier plates is provided with an opening that connects adjacent layers in the vertical direction via the rectifier plate.

8. n is an integer greater than or equal to 2, The heat recovery apparatus for high-temperature granular solids according to claim 7, wherein the openings in two vertically adjacent rectifier plates among the n rectifier plates are located on opposite sides of the first and second containers in the circumferential direction.

9. A heat recovery apparatus for high-temperature granular solids according to claim 8, wherein n is 3.

10. The connection portion of the connecting pipe to the side portion of the first container is located below the lowest of the n rectifier plates. The heat recovery apparatus for high-temperature granular solids according to any one of claims 7 to 9, wherein the opening of the lowest rectifier plate and the connecting portion are located on opposite sides of the first container and the second container in the circumferential direction.

11. The connection portion of the gas supply pipe to the side portion of the second container is located above the uppermost of the n rectifier plates. The heat recovery apparatus for high-temperature granular solids according to any one of claims 7 to 9, wherein the opening of the uppermost rectifier plate and the connecting portion are located on opposite sides of the first container and the second container in the circumferential direction.

12. A method for recovering heat from high-temperature granular solids, comprising using a heat recovery apparatus for high-temperature granular solids described in claim 1 to recover heat from the high-temperature granular solids with the gas.

13. The method for recovering heat from high-temperature granular solids according to claim 12, wherein the high-temperature granular solid is steel slag.

14. The method for recovering heat from high-temperature granular solids according to claim 13, wherein the steel slag is steelmaking slag.

15. A method for recovering heat from high-temperature granular solids according to any one of claims 12 to 14, wherein the gas contains carbon dioxide and water vapor, or both, and in addition to the heat recovery, a reaction is carried out between the high-temperature granular solids and the gas.

16. A first container having a first space inside for containing steel slag and having cylindrical sides that partition the first space, A second container having a cylindrical side portion that is positioned around the side portion of the first container and partitions a second space between itself and the side portion of the first container, A gas outlet is located within the first space and communicates with the second space, A method for recovering heat from steel slag using a heat recovery apparatus for steel slag, which is configured to have a gas supply to the second space, send the gas from the gas outlet to the first space via the second space, and recover the gas from the first space, thereby enabling heat recovery from the steel slag using the gas.

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