Heat recovery and utilization system

Abstract

To provide a heat recovery and utilization system capable of utilizing high-temperature and high-pressure steam in an increased amount while efficiently recovering heat.SOLUTION: A heat recovery and utilization system comprises: a circulation line 4 where a first medium is circulated; a first heat exchanger 2 which heats a first medium in a liquid state through heat exchange with a heat source medium; a high-pressure flush tank 6 into which the first medium in the liquid state heated in the first heat exchanger is introduced; at least one low-pressure flush tank 8 into which the first medium in the liquid state is introduced from the high-pressure flush tank; a steam supply line 10 which introduces steam of the first medium generated in the high-pressure flush tank into a heat utilization facility; a steam merging line 12 which merges the steam of the first medium generated in the low-pressure flush tank into the steam of the first medium from the high-pressure flush tank; and at least one low-pressure stage compressor 14 which is installed on the steam merging line and boosts the steam of the first medium from the low-pressure flush tank.SELECTED DRAWING: Figure 1

Description

[Technical field]

[0001] The present disclosure relates to a heat recovery and utilization system. [Background technology]

[0002] A technology has been proposed that efficiently recovers waste heat by generating flash steam from a liquid heated by a heat source medium (exhaust gas, etc.).

[0003] Patent document 1 describes a method in which liquid (water) heated by heat exchange with exhaust gas from a gas turbine is sequentially introduced into multiple flash tanks, and flash steam of different pressures is sequentially generated and utilized in the multiple flash tanks. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Patent Publication No. 2021-85608 Summary of the Invention [Problem to be solved by the invention]

[0005] Among multiple flash tanks into which liquid heated by heat exchange with a heat source medium is led, the temperature and pressure of the flash steam obtained in the later flash tanks are lower than those of the earlier flash tanks, so the amount of flash steam available at high temperature or pressure is limited. Therefore, it is desirable to obtain more high-temperature, high-pressure steam while efficiently recovering heat.

[0006] In view of the above circumstances, an object of at least one embodiment of the present invention is to provide a heat recovery and utilization system that can utilize a larger amount of high-temperature, high-pressure steam while efficiently recovering heat. [Means for solving the problem]

[0007] A heat recovery and utilization system according to at least one embodiment of the present invention includes: a circulation line through which the first medium circulates; a first heat exchanger for heating the first medium in a liquid state flowing through the circulation line by heat exchange with a heat source medium; a high-pressure flash tank provided in the circulation line and into which the first medium in a liquid state heated by the first heat exchanger is introduced; At least one low-pressure flash tank provided in the circulation line and into which the first medium in a liquid state is guided from the high-pressure flash tank; a steam supply line for guiding the steam of the first medium generated in the high-pressure flash tank to a heat utilization facility; a vapor merging line for merging the vapor of the first medium generated in the at least one low-pressure flash tank with the vapor of the first medium from the high-pressure flash tank flowing through the vapor supply line; at least one low-pressure stage compressor provided in the vapor merging line for pressurizing the vapor of the first medium from the at least one low-pressure flash tank; Equipped with. Effect of the Invention

[0008] According to at least one embodiment of the present invention, a heat recovery and utilization system is provided that can utilize a larger amount of high-temperature, high-pressure steam while efficiently recovering heat. [Brief description of the drawings]

[0009] [Figure 1] 1 is a schematic configuration diagram of a heat recovery and utilization system according to an embodiment. [Diagram 2] 1 is a schematic configuration diagram of a heat recovery and utilization system according to an embodiment. [Diagram 3] 1 is a schematic configuration diagram of a heat recovery and utilization system according to an embodiment. [Figure 4] 1 is a schematic configuration diagram of a heat recovery and utilization system according to an embodiment. [Diagram 5] 1 is a schematic configuration diagram of a heat recovery and utilization system according to an embodiment. [Figure 6] 1 is a schematic configuration diagram of a heat recovery and utilization system according to an embodiment. [Figure 7] 1 is a schematic configuration diagram of a heat recovery and utilization system according to an embodiment. [Figure 8] 1 is a schematic configuration diagram of a heat recovery and utilization system according to an embodiment. [Figure 9] 1 is a schematic configuration diagram of a heat recovery and utilization system according to an embodiment. [Figure 10] 1 is a schematic configuration diagram of a heat recovery and utilization system according to an embodiment. [Figure 11] 1 is a schematic configuration diagram of a heat recovery and utilization system according to an embodiment. [Figure 12] 1 is a schematic configuration diagram of a heat recovery and utilization system according to an embodiment. [Figure 13] 1 is a schematic configuration diagram of a heat recovery and utilization system according to an embodiment. [Figure 14] 1 is a schematic configuration diagram of a heat recovery and utilization system according to an embodiment. [Figure 15] 1 is a schematic configuration diagram of a heat recovery and utilization system according to an embodiment. [Figure 16] 4 is a graph showing an example of temperatures and heat exchange amounts of a heat source medium and a first medium in a first heat exchanger. [Figure 17] 4 is a graph showing an example of temperatures and heat exchange amounts of a medium to be heated and a first medium in a heat utilization facility. [Figure 18] FIG. 1 is a schematic diagram of a typical heat recovery and utilization system. [Figure 19] 1 is a graph showing an example of the relationship between the temperatures and entropy of a first heat medium and a heat source medium in a typical heat recovery and utilization system. [Figure 20] 2 is a graph showing an example of the relationship between the temperature and the entropy of the first heat medium and the heat source medium in the heat recovery and utilization system 1 shown in FIG. [Figure 21] 7 is a graph showing an example of the relationship between the temperature and the entropy of the first heat medium and the heat source medium in the heat recovery and utilization system 1 shown in FIG. 6. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0010] Hereinafter, some embodiments of the present invention will be described with reference to the accompanying drawings. However, the dimensions, materials, shapes, relative arrangements, etc. of components described as the embodiments or shown in the drawings are merely illustrative examples and are not intended to limit the scope of the present invention.

[0011] (Configuration of heat recovery and utilization system) 1 to 15 are schematic configuration diagrams of a heat recovery and utilization system according to an embodiment. As shown in Fig. 1 to 15, a heat recovery and utilization system 1 according to some embodiments includes a circulation line 4 through which a first medium (e.g., water) circulates, a first heat exchanger 2 for heating the first medium flowing through the circulation line 4, and a high-pressure flash tank 6 and at least one low-pressure flash tank 8 each provided in the circulation line 4.

[0012] The first heat exchanger 2 is configured to heat the first medium in a liquid state flowing through the circulation line 4 by heat exchange with a heat source medium. A relatively high-temperature fluid can be used as the heat source medium. For example, the heat source medium can be combustion exhaust gas from a combustion device, reaction gas after a chemical reaction at high temperature, gas condensed in a condenser in a distillation facility, hot spring water, or hot water heated by solar heat.

[0013] 9 to 13, the first heat exchanger 2 may be configured to receive exhaust gas from an exhaust gas generation facility 50 as a heat source medium. The exhaust gas generation facility 50 may include, for example, a gas turbine, a boiler, a gas engine, a fuel cell (such as a solid oxide fuel cell (SOFC)), a blast furnace, a heat treatment furnace that burns fuel, a ceramic kiln, or a waste incinerator.

[0014] The high-pressure flash tank 6 is provided downstream of the first heat exchanger 2 in the circulation line 4. The first medium in a liquid state heated in the first heat exchanger is guided to the high-pressure flash tank 6 via the circulation line 4. A pressure reducing valve 5 for reducing the pressure of the first medium guided to the high-pressure flash tank 6 may be provided in the circulation line 4 on the inlet side of the high-pressure flash tank 6.

[0015] The high-pressure flash tank 6 is configured to generate steam (flash steam; saturated steam) by flashing (i.e., boiling under reduced pressure) the first medium. The flash steam of the first medium generated in the high-pressure flash tank 6 is supplied to the heat utilization facility 18 via a steam supply line 10. The steam supply line 10 may be connected to the top of the high-pressure flash tank 6.

[0016] In the high-pressure flash tank 6, flash steam of the first medium is generated and the saturation temperature T sat_H This first medium liquid is stored in the bottom of the high-pressure flash tank 6 and is guided via the circulation line 4 to a low-pressure flash tank 8, which will be described later.

[0017] The low-pressure flash tank 8 is provided downstream of the high-pressure flash tank 6 in the circulation line 4. The high-pressure flash tank 6 and the low-pressure flash tank 8 are connected via a connection line 4a that constitutes the circulation line 4. The first medium liquid in the high-pressure flash tank 6 is extracted from the bottom of the high-pressure flash tank 6 via the connection line 4a and guided to the low-pressure flash tank 8. The connection line 4a may be provided with a pressure reducing valve 7a for reducing the pressure of the first medium guided to the low-pressure flash tank 8.

[0018] The low-pressure flash tank 8 is configured to generate steam (flash steam; saturated steam) by flashing (i.e., boiling under reduced pressure) the first medium. In the low-pressure flash tank 8, flash steam at a lower pressure than the flash steam generated in the high-pressure flash tank 6 is generated. The flash steam of the first medium generated in the low-pressure flash tank 8 is configured to merge with the steam of the first medium (steam from the high-pressure flash tank 6) flowing through the steam supply line 10 via a merge line 12. One end of the merge line 12 may be connected to the top of the low-pressure flash tank 8, and the other end may be connected to the steam supply line 10.

[0019] In the low-pressure flash tank 8, flash steam of the first medium is generated and the saturation temperature T sat_L A first medium liquid is generated. This first medium liquid is stored in the bottom of the low-pressure flash tank 8 and sent to the first heat exchanger 2 via the circulation line 4. The circulation line 4 may be provided with a pump 9 for pumping the first medium in a liquid state from the low-pressure flash tank 8 toward the first heat exchanger 2.

[0020] The above-mentioned joining line 12 is provided with a low-pressure stage compressor 14 for pressurizing the vapor of the first medium from the low-pressure flash tank 8. That is, the flash vapor of the first medium generated in the low-pressure flash tank 8 is pressurized by the low-pressure stage compressor 14, whereby the flash vapor is heated and then flows into the vapor supply line 10. The flash vapor of the first medium from the low-pressure flash tank 8 that has flowed into the vapor supply line 10 is supplied to the heat utilization facility 18 together with the vapor of the first medium from the high-pressure flash tank 6. The low-pressure stage compressor 14 may be configured to pressurize the vapor of the first medium from the low-pressure flash tank 8 to a pressure equivalent to that of the vapor of the first medium from the high-pressure flash tank 6.

[0021] The heat recovery and utilization system 1 may include one or more of the above-mentioned low-pressure flash tanks 8. In the exemplary embodiment shown in Figs. 1 to 4 and 9 to 13, the heat recovery and utilization system 1 includes one low-pressure flash tank 8. In the exemplary embodiment shown in Figs. 5 to 8, the heat recovery and utilization system 1 includes multiple low-pressure flash tanks 8_1, ..., 8_i, ..., 8_n (where n is an integer of 2 or more; hereinafter, each of the low-pressure flash tanks 8_1 to 8_n will be collectively referred to as a low-pressure flash tank 8).

[0022] 5 to 8, the multiple low-pressure flash tanks 8_1 to 8_n are provided in this order from the upstream side in the circulation line 4. That is, the multiple low-pressure flash tanks 8 include a low-pressure flash tank 8_1 located on the most upstream side in the circulation line 4, and a low-pressure flash tank 8_n located on the most downstream side.

[0023] Of the multiple low-pressure flash tanks 8_1 to 8_n, the low-pressure flash tank 8_i and the low-pressure flash tank 8_(i+1) are connected via a connection line 4b_i that constitutes the circulation line 4. The connection line 4b_i may be provided with a pressure reducing valve 7b_i (hereinafter, each of the pressure reducing valves 7b_1 to 7b_(n-1) will be collectively referred to as pressure reducing valve 7b) for reducing the pressure of the first medium guided to the low-pressure flash tank 8.

[0024] Each low-pressure flash tank 8 is configured to generate steam (flash steam; saturated steam) by flashing (i.e., boiling under reduced pressure) the first medium. In the low-pressure flash tank 8 in the downstream stage (e.g., low-pressure flash tank 8_i), flash steam at a lower pressure is generated than the flash steam generated in the low-pressure flash tank 8 in the upstream stage (e.g., low-pressure flash tank 8_(i-1)). The flash steam of the first medium generated in each low-pressure flash tank 8 is merged with the steam of the first medium (steam from the high-pressure flash tank 6) flowing through the steam supply line 10 via the merge line 12. Here, the merge line 12 may include branch lines 12_1 to 12_n connected to the tops of the low-pressure flash tanks 8_1 to 8_n. In the exemplary embodiment shown in Figs. 5 to 8, the flash steam of the first medium generated in the low-pressure flash tanks 8_1 to 8_n is guided to the merge line 12 via the branch lines 12_1 to 12_n, respectively.

[0025] In the low-pressure flash tanks 8_1 to 8_n, flash steam of the first medium is generated, and the saturation temperature T sat_L1 ~T sat_Ln (T sat_L1 >T sat_Li >T sat_Ln ) of first medium liquid is generated. This first medium liquid is stored in the bottom of the low-pressure flash tanks 8_1 to 8_n. The first medium liquid in the low-pressure flash tank 8_i is extracted from the bottom of the low-pressure flash tank 8_i via a connection line 4b_i and guided to the low-pressure flash tank 8_(i+1). In addition, the first medium liquid in the low-pressure flash tank 8_n located at the most downstream side in the circulation line 4 is sent to the first heat exchanger 2 via the circulation line 4.

[0026] As shown in Fig. 5 to Fig. 8, the junction line 12 is provided with low-pressure stage compressors 14_1 to 14_n (hereinafter collectively referred to as low-pressure stage compressors 14) for pressurizing the vapor of the first medium from the low-pressure flash tanks 8_1 to 8_n, respectively. That is, the flash vapor of the first medium generated in the low-pressure flash tanks 8_1 to 8_n is pressurized by the low-pressure stage compressors 14_1 to 14_n, and thus heated, before flowing into the steam supply line 10. The flash vapor of the first medium from the low-pressure flash tanks 8_1 to 8_n that has flowed into the steam supply line 10 is supplied to the heat utilization facility 18 together with the vapor of the first medium from the high-pressure flash tank 6.

[0027] As shown in Fig. 5 or 7, the multiple low-pressure stage compressors 14_1 to 14_n may be provided in series with respect to the junction line 12. In this case, the pressure ratio of each of the multiple low-pressure stage compressors 14_1 to 14_n can be made small. Each low-pressure stage compressor 14_i may be configured to boost the pressure of the first medium vapor from the low-pressure flash tank 8_i to a pressure equivalent to that of the first medium vapor from the low-pressure flash tank 8_(i-1) in the upstream stage.

[0028] 6 or 8, the multiple low-pressure stage compressors 14_1 to 14_n may be provided in parallel with respect to the junction line 12. The multiple low-pressure stage compressors 14_1 to 14_n may be configured to boost the pressure of the first medium vapor from the low-pressure flash tanks 8_1 to 8_n to a pressure equivalent to that of the first medium vapor from the high-pressure flash tank 6.

[0029] The heat utilization equipment 18 is configured to receive the steam of the first medium from the steam supply line 10 and utilize it as a heat source. The heat utilization equipment 18 may be configured to heat the medium to be heated by heat exchange with the first medium.

[0030] The heat utilization equipment 18 may include, for example, a steam generator, a reactor, evaporator, or distillation tower for chemicals (ammonia, alcohol (methanol, ethanol, etc.) or hydrocarbons (propane, butane, pentane, hexane, cyclohexane, heptane, octane, nonane, decane, etc.), an evaporator or distillation tower for petroleum, an absorbent regeneration equipment for a carbon dioxide (CO2) recovery equipment, or a food heating equipment (boiling, steaming, heat sterilization, etc.) in a food factory. In the exemplary embodiment shown in Figures 9, 10, 14, and 15, the heat utilization equipment 18 includes a carbon dioxide recovery equipment 30.

[0031] The first medium used as a heat source in the heat utilization facility 18 may be returned to the circulation line 16 via a return line 16 .

[0032] According to the heat recovery and utilization system 1 of the above-mentioned embodiment, the first medium heated by heat exchange with the heat source medium in the first heat exchanger 2 is flashed in the high-pressure flash tank 6 and the low-pressure flash tank 8 in sequence to generate steam (flash steam). Therefore, compared to the case where only one stage of flash tanks is provided, steam can be taken out until the first medium becomes lower in temperature. In addition, the relatively low-temperature, low-pressure steam generated in the low-pressure flash tank 8 is compressed by the low-pressure stage compressor 14, so that the steam compressed in this manner can be used as high-temperature, high-pressure steam together with the steam generated in the high-pressure flash tank 6. Therefore, with the configuration according to the above-mentioned embodiment, a larger amount of high-temperature, high-pressure steam can be generated and utilized with a relatively small compressor power.

[0033] This will be explained using the drawings. Fig. 18 is a schematic diagram of a heat recovery and utilization system 100 provided with only one stage of flash tanks. In Fig. 18, the same elements as those in the heat recovery and utilization system 1 according to the embodiment are denoted by the same reference numerals. Fig. 19 is a graph showing an example of the relationship between the temperatures and entropy of the first heat medium and the heat source medium in the heat recovery and utilization system 100 shown in Fig. 18. Fig. 20 is a graph showing an example of the relationship between the temperatures and entropy of the first heat medium and the heat source medium in the heat recovery and utilization system 1 (including the high-pressure flash tank 6 and the low-pressure flash tank 8) shown in Fig. 1.

[0034] In the example shown in Fig. 19 and Fig. 20, in the first heat exchanger 2, the heat source medium (exhaust gas, etc.) and the first medium (water, etc.) exchange heat without undergoing a phase change. Also, the temperatures of the first medium at the inlet and outlet of the first heat exchanger 2 are T1 and T2, respectively, and the temperature difference between the heat source medium and the first medium at each position of the first heat exchanger 2 is Td (for example, 10°C). In this case, the temperatures of the heat source medium at the inlet and outlet of the first heat exchanger 2 are (T2+Td) and (T1+Td), respectively. In Fig. 19 and Fig. 20, the temperature of the heat source medium at the inlet of the first heat exchanger 2 is (T2+Td), which is common.

[0035] In the heat recovery and utilization system 100 shown in FIG. 18, as shown in the graph of FIG. 19, the first medium heated to T2 in the first heat exchanger 2 is introduced into the flash tank 106, and the first medium is heated to a saturation temperature T sat_H The first medium vapor and liquid are generated at a saturation temperature T sat_H The first medium, steam, is used and has a saturation temperature T sat_H The liquid of the first medium (=T1) returns to the first heat exchanger 2. Therefore, the amount of heat HR_H recovered and utilized in the heat recovery and utilization system 100 is represented by the area shown in FIG. 19. In addition, the temperature of the heat source medium at the outlet of the first heat exchanger 2 is (T sat_H +Td).

[0036] On the other hand, in the heat recovery and utilization system 1 according to the embodiment shown in FIG. 1, as shown in the graph of FIG. 20, the first medium heated to T2 in the first heat exchanger 2 is introduced into the high-pressure flash tank 6, and the first medium is heated to a saturation temperature T sat_H The vapor and liquid of the first medium are generated. sat_H is equal to T1 in FIG. 19. The amount of heat HR_H recovered and utilized through the generation of flash steam in the high-pressure flash tank 6 is represented by the area shown in FIG. 20, which is equal to the area of ​​the amount of heat HR_H in FIG. 19. In addition, the saturation temperature T sat_H The liquid of the first medium is led to the low-pressure flash tank 8, where it is heated to a lower saturation temperature T sat_L The amount of heat HR_L recovered and utilized through the generation of flash steam in the low-pressure flash tank 8 is represented by the area shown in FIG. sat_L (=T1) is lower than T1 in FIG. 19. Also, the saturation temperature T sat_L The vapor of the first medium (=T1) is compressed by the low-pressure compressor 14 to a saturation temperature of T sat_H The compressor power required to raise the temperature to HR_H is defined as P_L. Then, the amount of heat available in the heat recovery and utilization system 1 is the sum of HR_H, HR_L, and P_L. This area is larger than the amount of heat available in the heat recovery and utilization system 100 in FIG. 18 (the amount of heat HR_H in FIG. 19). In addition, the temperature of the heat source medium at the outlet of the first heat exchanger 2 is (T sat_L +Td), and the heat of the heat source medium can be recovered until the temperature of the heat source medium becomes lower than in the case of FIG. 18. By adding a relatively small compressor power P_L, not only P_L but also the heat HR_L of the heat source medium, which was wasted in the heat recovery utilization system 100 of FIG. 18, can be recovered to a temperature T sat_H In addition, the liquid first medium whose temperature has been reduced in the low-pressure flash tank 8 is sent to the first heat exchanger 2, so that the heat of the heat source medium can be recovered in the first heat exchanger 2 to a low temperature.

[0037] In this way, in the configuration according to the embodiment described above, a larger amount of high-temperature, high-pressure steam can be generated and utilized with a relatively small compressor power. That is, according to the embodiment described above, a larger amount of high-temperature, high-pressure steam can be utilized while efficiently recovering heat.

[0038] FIG. 21 is a graph showing an example of the relationship between the temperature and entropy of the first heat medium and the heat source medium in the heat recovery and utilization system 1 (including the high-pressure flash tank 6 and multiple (here, three) low-pressure flash tanks 8_1 to 8_3) shown in FIG. 6.

[0039] In the heat recovery and utilization system 1 shown in FIG. 6, as shown in the graph of FIG. 21, the first medium heated to T2 in the first heat exchanger 2 is introduced into the high-pressure flash tank 6, and the first medium is heated to a saturation temperature T sat_H The amount of heat HR_H recovered and utilized through the generation of flash steam in the high-pressure flash tank 6 is represented by the area shown in FIG. 21, which is equal to the area of ​​the amount of heat HR_H in FIGS. 19 and 20. In addition, the saturation temperature T sat_H The liquid of the first medium is successively guided to the low-pressure flash tanks 8_1 to 8_3, where it is heated to a lower saturation temperature T sat_L1 , T sat_L2 and T sat_L3 The heat amount HR_L1, the heat amount HR_L2, and the heat amount HR_L3 recovered and utilized through the generation of flash steam in the low-pressure flash tanks 8_1 to 8_3 are represented by the areas shown in FIG. 21. Also, the saturation temperature T sat_L1 , T sat_L2 and T sat_L3 The steam of the first medium (=T1) is compressed by the low-pressure compressors 14_1 to 14_3 to a saturation temperature of T sat_HThe compressor powers required to raise the temperature to HR_H are P_L1, P_L2, and P_L3. Then, the amount of heat available in the heat recovery and utilization system 1 is the sum of HR_H, HR_L1, HR_L2, HR_L3, P_L1, P_L2, and P_L3. This area is larger than the amount of heat available in the heat recovery and utilization system 100 in FIG. 18 (the amount of heat HR_H in FIG. 19). Also, the sum of the areas of the compressor powers P_L1, P_L2, and P_L3 in FIG. 21 is smaller than the area of ​​the compressor power P_L in FIG. 20. Therefore, it can be seen that by using the heat recovery and utilization system 1 including multiple low-pressure flash tanks 8, a large amount of heat can be recovered and utilized with a smaller compressor power. Furthermore, in the heat recovery and utilization system 1 of Fig. 5 or Fig. 6, the first medium, which is a liquid whose temperature has been reduced in the low-pressure flash tank 8_n (n=3 in Fig. 21) having a lower pressure than the heat recovery and utilization system 1 of Fig. 1, is sent to the first heat exchanger 2, so that it becomes possible to recover the heat of the heat source medium in the first heat exchanger 2 to a lower temperature than the heat recovery and utilization system 1 of Fig. 1. Note that such an effect can also be obtained in the case of providing a high-pressure stage compressor 20 that further pressurizes the steam generated in the high-pressure flash tank 6 as in Fig. 7 or Fig. 8. In addition, such an effect can be obtained in both cases where the low-pressure stage compressors 14_1 to 14_n and the high-pressure stage compressor 20 are provided in series (for example, Figs. 5 and 7) and where the low-pressure stage compressors 14_1 to 14_n and the high-pressure stage compressor 20 are provided in parallel (for example, Figs. 6 and 8).

[0040] In some embodiments, the first heat exchanger 2 is configured so that the first medium and the heat source medium exchange heat without undergoing a phase change.

[0041] Here, Fig. 16 is a graph showing an example of the temperature and heat exchange amount of the heat source medium and the first medium in the first heat exchanger 2. In the graph of Fig. 16, the solid line indicates the temperature change when the first medium does not undergo a phase change in the first heat exchanger 2 (i.e., when it remains liquid), and the dashed line indicates the temperature change when the first medium undergoes a phase change in the first heat exchanger 2 (i.e., when it changes from liquid to gas). Also, in the graph of Fig. 16, the dashed line indicates the temperature change when the heat source medium does not undergo a phase change in the first heat exchanger 2 (for example, when exhaust gas or the like remains gas).

[0042] 16, when the heat source medium and the first medium do not change phase, the temperature difference Td1 between the heat source medium and the first medium is kept small from the inlet to the outlet of the first heat exchanger 2, resulting in good heat utilization efficiency and effective utilization of high-temperature heat. On the other hand, when the heat source medium does not change phase but the first medium does change phase, the temperature difference Td2 between the heat source medium and the first medium becomes large depending on the position of the first heat exchanger 2, resulting in reduced heat utilization efficiency.

[0043] In this regard, according to the above-mentioned embodiment, the first medium and the heat source medium are arranged to exchange heat without undergoing a phase change in the first heat exchanger 2, so the temperature difference between the heat source medium and the first medium can be reduced compared to a case where either the first medium or the heat source medium does not undergo a phase change and the other undergoes a phase change during heat exchange, thereby improving the efficiency of heat utilization of the heat source medium.

[0044] In some embodiments, the heat utilization facility 18 is configured to perform heat exchange between the heated medium and the first medium while changing phases.

[0045] Here, Fig. 17 is a graph showing an example of the temperature and heat exchange amount of the heated medium and the first medium in the heat utilization equipment 18. In the graph of Fig. 17, the solid line shows the temperature change when the first medium undergoes a phase change (i.e., when vapor condenses) in the heat utilization equipment 18, and the dashed line shows the temperature change when the first medium does not undergo a phase change (i.e., when it remains as vapor) in the heat utilization equipment 18. Also, in the graph of Fig. 17, the two-dot chain line shows the temperature change when the heated medium undergoes a phase change in the heat utilization equipment 18 (for example, when liquid evaporates, etc.).

[0046] 17, when the heated medium and the first medium undergo a phase change, the temperature difference Td3 between the first medium and the heated medium is kept small from the inlet to the outlet of the heat utilization equipment 18, so the heat utilization efficiency is good and high-temperature heat can be effectively utilized. On the other hand, when the first medium does not undergo a phase change but the heated medium does undergo a phase change, the temperature difference Td4 between the first medium and the heated medium becomes large depending on the position of the heat utilization equipment 18, and the heat utilization efficiency decreases.

[0047] In this regard, according to the embodiment described above, the heated medium and the first medium are configured to exchange heat while undergoing phase changes in the heat utilization equipment 18, so the temperature difference between the first medium and the heated medium can be reduced compared to a case in which either the heated medium or the first medium undergoes a phase change while the other does not undergo a phase change for heat exchange. Therefore, the heat utilization efficiency of the heat source medium can be improved.

[0048] In some embodiments, the return line 16 for returning the first medium from the heat utilization facility 18 to the circulation line 4 is configured to return the first medium to a position on the circulation line 4 downstream of the high-pressure flash tank 6 and upstream of the most downstream low-pressure flash tank 8 located at the most downstream side among at least one low-pressure flash tank 8, or to the most downstream low-pressure flash tank 8. Here, when the heat recovery utilization system 1 has one low-pressure flash tank 8, the one low-pressure flash tank 8 is the most downstream low-pressure flash tank. When the heat recovery utilization system 1 has multiple low-pressure flash tanks 8_1 to 8_n, the low-pressure flash tank 8_n located at the most downstream side is the most downstream low-pressure flash tank.

[0049] 1, 5, 6, and 9 to 15, the return line 16 is configured to return the first medium to the connection line 4a provided in the circulation line 4 at a position downstream of the high-pressure flash tank 6 and upstream of the most downstream low-pressure flash tank 8 (or 8_n). In the exemplary embodiment shown in FIG. 2, the return line 16 is configured to return the first medium to the most downstream low-pressure flash tank 8.

[0050] In the above-mentioned embodiment, the first medium used as a heat source in the heat utilization facility 18 is returned to the circulation line 4 and flashed again in the low-pressure flash tank 8 to generate steam (flash steam), which is then pressurized by the low-pressure stage compressor 14 and supplied to the heat utilization facility 18. That is, according to the above-mentioned embodiment, the relatively high-temperature and high-pressure first medium after being used as a heat source in the heat utilization facility 18 is led to the low-pressure flash tank 8 to further utilize the heat remaining in the first medium. As a result, the temperature of the first medium at the inlet of the first heat exchanger 2 is lowered compared to the case where the first medium at the outlet of the heat utilization facility 18 is sent directly to the first heat exchanger 2, so that the heat of the heat source medium can be recovered until the heat source medium becomes lower. Therefore, according to the above-mentioned embodiment, it is possible to utilize a larger amount of high-temperature and high-pressure steam while recovering heat more efficiently.

[0051] In some embodiments, the temperature of the first medium from the heat utilization facility 18 is T TUD When the saturation temperature at the pressure in the flash tank (high-pressure flash tank 6 or low-pressure flash tank 8) is the above-mentioned temperature T TUD The flash tank has a saturation temperature of 1000°C or higher than the above-mentioned temperature T TUD The first medium from the heat utilization facility 18 may be returned to the circulation line 4 via a return line 16 to a portion of the circulation line 4 between the following flash tank (connection line 4a or 4b).

[0052] For example, when the heat recovery and utilization system 1 includes multiple low-pressure flash tanks 8, the saturation temperature at the pressure in the high-pressure flash tank 6 is T sat_H The saturation temperatures at the pressures in the low-pressure flash tanks 8_1 to 8_n are T sat_L1 ~T sat_Ln Then, T sat_H >T TUD ≧T sat_L1 In this case, when the return line 16 is configured to return the first medium from the heat utilization facility 18 to a portion (connection line 4a) of the circulation line 4 between the high-pressure flash tank 6 and the first-stage low-pressure flash tank 8_1, which is the most upstream of the circulation line 4, among one or more low-pressure flash tanks 8, T sat_L1 By effectively using the first medium from the heat utilization equipment 18 having a temperature above this, it is possible to generate steam with the highest pressure and saturation temperature among the steam generated in the low-pressure flash tank 8, which is preferable because it allows more high-temperature, high-pressure steam to be utilized while more efficiently recovering heat (see Figures 5 and 6).

[0053] In some embodiments, as shown in, for example, Figures 3, 4, 7, and 8, the heat recovery and utilization system 1 includes a high-pressure stage compressor 20 provided in the steam supply line 10 for boosting the steam of the first medium from the high-pressure flash tank 6. As shown in Figures 3, 4, and 7, the high-pressure stage compressor 20 may be configured to boost the steam of the first medium from the high-pressure flash tank 6 together with the steam of the first medium that has merged into the steam supply line 10 from the merge line 12. Alternatively, as shown in Figure 8, the high-pressure stage compressor 20 may be configured to boost the steam of the first medium from the high-pressure flash tank 6 separately from the steam of the first medium that has merged into the steam supply line 10 from the merge line 12.

[0054] According to the above-described embodiment, by pressurizing the relatively high temperature and pressure flash steam of the first medium generated in the high-pressure flash tank 6 using the high-pressure stage compressor 20, it is possible to utilize steam with even higher temperature and pressure in the heat utilization equipment 18 (for example, steam with a higher temperature than the temperature of the heat source medium in the first heat exchanger 2).

[0055] As shown in FIGS. 3, 4, 7, and 8, when a high-pressure stage compressor 20 for compressing the vapor of the first medium from the high-pressure flash tank 6 is provided, the temperature T TUD is the saturation temperature T at the pressure in the high-pressure flash tank 6 sat_H and the first medium after heat utilization in the heat utilization equipment 18 is returned to the circulation line 4 via a return line 16 that connects the heat utilization equipment 18 to a portion of the circulation line 4 downstream of the first heat exchanger 2 and upstream of the high-pressure flash tank 6. According to this configuration, the first medium from the heat utilization equipment 18, which has a high temperature, can be effectively used to generate steam in the high-pressure flash tank 6 at a higher pressure and saturation temperature than in the low-pressure flash tank 8, and this is preferable because it allows more high-temperature and high-pressure steam to be utilized while more efficiently recovering heat.

[0056] 3, 4, and 7, the heat recovery and utilization system 1 includes a cooling section 22 provided between the low-pressure stage compressor 14 and the high-pressure stage compressor 20 for cooling the vapor of the first medium pressurized by the low-pressure stage compressor 14. When the heat recovery and utilization system 1 includes a plurality of low-pressure stage compressors 14, the cooling section 22 is provided between the low-pressure stage compressor 14 corresponding to the low-pressure flash tank 8 on the most upstream side and the high-pressure stage compressor 20.

[0057] In the above embodiment, the first medium vapor compressed in the low-pressure stage compressor 14 is cooled in the cooling section 22 before being introduced into the high-pressure stage compressor 20, so that the compressor power of the high-pressure stage compressor 20 can be reduced. Therefore, more high-temperature, high-pressure vapor can be used while efficiently recovering heat. Furthermore, since the degree of superheat and the temperature of the first medium vapor at the outlet of the high-pressure stage compressor 20 can be reduced, it becomes possible to use inexpensive materials, inexpensive seals and bearings in the high-pressure stage compressor 20. Meanwhile, the first medium is cooled in the cooling section 22 within the range of the superheated state, and the saturation temperature does not change significantly. Therefore, when the heat utilized in the heat utilization facility 18 is the condensation heat when the first medium vapor is condensed, the reduction in the amount of heat available in the heat utilization facility 18 is small.

[0058] When the heat recovery utilization system 1 includes a plurality of low-pressure stage compressors 14, the heat recovery utilization system 1 may include a cooling section 28 (cooling sections 28_1, ..., 28_i, ... in Figure 7; hereinafter collectively referred to as cooling section 28) provided between a pair of low-pressure stage compressors 14 for cooling the vapor of the first medium pressurized by the low-pressure stage compressor 14 corresponding to the low-pressure flash tank 8 downstream (low-pressure side) of the pair of low-pressure stage compressors 14.

[0059] In the above-described embodiment, the first medium vapor compressed in the low-pressure stage compressor 14 corresponding to the downstream low-pressure flash tank 8 is cooled in the cooling section 28 and then introduced into the low-pressure stage compressor 14 corresponding to the upstream low-pressure flash tank 8, so that the compressor power of the low-pressure stage compressor 14 corresponding to the upstream low-pressure flash tank 8 can be reduced. Therefore, more high-temperature, high-pressure vapor can be used while efficiently recovering heat.

[0060] The cooling units 22, 28 may be configured to spray the first medium in a liquid state from the circulation line 4 onto the vapor of the first medium pressurized by the low-pressure stage compressor 14. In this way, by spraying the first medium in a liquid state from the circulation line 4, vaporizing it, and removing the heat of vaporization from the vapor of the first medium pressurized by the low-pressure stage compressor 14, it is possible to appropriately cool the vapor of the first medium compressed by the low-pressure stage compressor 14.

[0061] 3 and 7, the cooling section 22 includes a cooling liquid line 25 configured to extract the first medium in a liquid state from the circulation line 4, and a spray 24 configured to spray the first medium in a liquid state from the cooling liquid line 25 toward the vapor of the first medium compressed by the low-pressure stage compressor 14. The spray 24 may be provided at a position (steam supply line 10) downstream of a junction J between the steam supply line 10 and the junction line 12 as shown in FIGS. 3 and 7, or may be provided at a position (junction line 12) upstream of the junction J.

[0062] In the exemplary embodiment shown in FIG. 7 , the cooling section 28 includes a spray 28 configured to spray the first medium in a liquid state from the above-mentioned cooling liquid line 25 onto the vapor of the first medium pressurized in the low-pressure stage compressor 14 corresponding to the upstream low-pressure flash tank 8 of the pair of low-pressure stage compressors 14.

[0063] Alternatively, the cooling units 22, 28 may be configured to cool the vapor of the first medium pressurized in the low-pressure stage compressor 14 by heat exchange with the first medium in a liquid state from the circulation line 4. In this way, the vapor of the first medium compressed in the low-pressure stage compressor 14 can be appropriately cooled by heat exchange with the first medium in a liquid state from the circulation line 4.

[0064] In the exemplary embodiment shown in FIG. 4 , the cooling section 22 includes a heat exchange section 26 configured to exchange heat between the first medium in a liquid state in the high-pressure flash tank 6 and the vapor of the first medium pressurized in the low-pressure stage compressor 14.

[0065] In the above-described embodiment, the vapor of the first medium pressurized in the low-pressure stage compressor 14 is cooled by heat exchange with the first medium in a relatively high-temperature liquid state in the high-pressure flash tank 6, thereby making it possible to suppress the generation of liquid droplets at the inlet of the high-pressure stage compressor 20 due to excessive cooling of the vapor of the first medium.

[0066] In some embodiments, as shown in, for example, FIGS. 10 to 15, the heat recovery and utilization system 1 includes a heat recovery steam generator (HRSG) for recovering heat of the exhaust gas from the exhaust gas generation facility 50. The heat recovery steam generator 60 includes a duct 62 to which exhaust gas is introduced, and at least one second heat exchanger provided in the duct 62 for heating a second medium (water or the like) by heat exchange with the exhaust gas to generate steam. In the illustrated embodiment, the at least one second heat exchanger includes an evaporator 66a, a superheater 66b, a coal economizer 66c, an evaporator 68a, and / or a superheater 68b. The heat recovery steam generator 60 may also include steam drums 67 and / or 69 for temporarily storing the steam generated in the evaporators 66a and / or 68a. The exhaust gas from the exhaust gas generation facility 50 is introduced to the duct 62 via an exhaust gas introduction line 52, and is discharged from the duct 62 via an exhaust line 54.

[0067] In some embodiments, the first heat exchanger 2 of the heat recovery utilization system 1 is provided downstream of at least one second heat exchanger in the flow of exhaust gas in the duct 62 of the exhaust heat recovery boiler 60, and is configured to heat the first medium by heat exchange with the exhaust gas from the exhaust gas generation facility 50 as a heat source medium. That is, in some embodiments, the first heat exchanger 2 may be one of a plurality of heat exchangers constituting the exhaust heat recovery boiler 60. In the exemplary embodiment shown in Figs. 10 to 15, the first heat exchanger 2 functions as an economizer 64 for heating the second medium before it is supplied to the plurality of second heat exchangers.

[0068] In the above-described embodiment, in the heat recovery boiler 60, in addition to generating steam of the second medium by heat exchange in the second heat exchanger (evaporator 66a, superheater 66b, economizer 66c, evaporator 68a and / or superheater 68b) using heat of the exhaust gas from the exhaust gas generation facility 50, the first medium heated by heat exchange with the exhaust gas whose temperature has been reduced by passing through the second heat exchanger can be introduced into the high-pressure flash tank 6 and the low-pressure flash tank 8 to generate steam (flash steam). Thus, according to the above-described embodiment, it is possible to utilize a larger amount of high-temperature, high-pressure steam while efficiently recovering heat.

[0069] In some embodiments, as shown in, for example, Figs. 10 to 15, the heat recovery and utilization system 1 includes a branch line 56A and / or 56B that branches from a portion of the circulation line 4 downstream of the first heat exchanger 2 (the economizer 64 in the heat recovery boiler 60) and upstream of the high-pressure flash tank 6, and guides a part of the first medium flowing through the portion to any of the above-mentioned second heat exchangers as the second medium. The heat recovery and utilization system 1 shown in Figs. 10 to 15 includes the branch line 56A, and the branch line 56A is configured to guide the second medium to the evaporator 66a, the superheater 66b, and / or the economizer 66c, which are the second heat exchangers. The heat recovery and utilization system 1 shown in Figs. 12 to 15 further includes a branch line 56B, and the branch line 56B is configured to guide the second medium to the evaporator 68a and / or the superheater 66b, which are the second heat exchangers.

[0070] In addition, the first medium and the second medium are usually the same type of substance, typically water. As shown in the figure, the branch lines 56A and 56B may be provided with valves 57A and 57B for adjusting the amount of the second medium supplied to the evaporators 66a and 68a.

[0071] According to the above-described embodiment, a portion of the first medium heated by heat exchange with the exhaust gas in the first heat exchanger 2 can be guided as the second medium to the second heat exchanger of the exhaust heat recovery boiler 60 via the branch line 56. That is, the first medium guided to the high-pressure flash tank 6 and the low-pressure flash tank 8, and the second medium guided to the second heat exchanger, can be heated by heat exchange with the relatively low-temperature exhaust gas in the first heat exchanger 2. Therefore, according to the above-described embodiment, it is possible to utilize a larger amount of high-temperature, high-pressure steam while efficiently recovering heat.

[0072] 12 to 15, for example, at least one second heat exchanger includes a plurality of evaporators 66a, 68a for generating steam having different pressures. The branch line 56B is configured to guide a portion of the first medium flowing in a portion of the circulation line 4 downstream of the first heat exchanger 2 (the economizer 64 in the heat recovery boiler 60) and upstream of the high-pressure flash tank 6 to the evaporator 68a, which is provided in the duct 62 at the most downstream side in the flow of the exhaust gas, among the plurality of evaporators 66a, 68a.

[0073] According to the above-described embodiment, a part of the first medium heated by heat exchange with the exhaust gas in the first heat exchanger 2 can be guided as the second medium to the evaporator 68a arranged at the most downstream side in the duct 62 via the branch line 56B. That is, the first medium guided to the high-pressure flash tank 6 and the low-pressure flash tank 8, and the second medium guided to the above-described evaporator 68a can be heated by heat exchange with the relatively low-temperature exhaust gas in the first heat exchanger 2. Therefore, according to the above-described embodiment, it is possible to utilize a larger amount of high-temperature, high-pressure steam while efficiently recovering heat.

[0074] A heat recovery and utilization system 1 according to some embodiments includes a steam utilization facility 58 configured to utilize steam of the second medium generated in a heat recovery boiler 60, as shown in, for example, FIGS.

[0075] In some embodiments, the steam utilization facility 58 may be configured to heat the medium to be heated by heat exchange with the steam of the second medium. As shown in Fig. 10, the drain water from the steam utilization facility 58 may be supplied to the high-pressure flash tank 6 via the circulation line 4.

[0076] In some embodiments, as shown in, for example, FIGS. 11 to 15 , the steam utilization facility 58 may include a steam turbine 72 configured to be driven by the steam of the second medium generated in the heat recovery steam generator 60. The steam turbine 72 may be configured to drive a generator 74. The steam of the second medium that has done work in the steam turbine 72 is discharged from the steam turbine 72 via a turbine outlet line 76.

[0077] According to the above-described embodiment, in the heat recovery boiler 60, in addition to generating steam (steam of the second medium) for driving the steam turbine 72 through heat exchange in the second heat exchanger using heat from the exhaust gas from the exhaust gas generation facility 50, the first medium heated through heat exchange with the exhaust gas whose temperature has been reduced by passing through the second heat exchanger can be introduced into the high-pressure flash tank 6 and the low-pressure flash tank 8 to generate steam (flash steam). Thus, according to the above-described embodiment, it is possible to utilize more high-temperature, high-pressure steam while efficiently recovering heat.

[0078] In some embodiments, as shown in, for example, Figures 11, 12, 14, and 15, the turbine outlet line 76 is connected to the steam supply line 10. Then, the steam of the second medium flowing through the turbine outlet line 76 merges with the steam of the first medium in the steam supply line 10, and is supplied to the heat utilization facility 18 together with the steam of the first medium.

[0079] According to the above-described embodiment, in addition to the steam (flash steam) generated in the high-pressure flash tank 6 and the low-pressure flash tank 8, steam discharged from the steam turbine 72 is also supplied to the heat utilization equipment 18 via the steam supply line 10, so that more high-temperature, high-pressure steam can be utilized while efficiently recovering heat.

[0080] 12 to 15, when multiple evaporators 66a, 68a are included, steam from the evaporator 66a that generates higher pressure steam may be supplied to the inlet of the steam turbine 72. Steam from the evaporator 68a that generates lower pressure steam may be guided to a turbine outlet line 76 and merged with steam discharged from the steam turbine 72, as shown in, for example, Figures 12, 14, and 15, or may be supplied to an intermediate stage of the steam turbine 72, as shown in, for example, Figure 13.

[0081] 13, the steam discharged from the steam turbine 72 may be guided to a condenser 77 via a turbine outlet line 76. The second medium in a liquid state condensed in the condenser 77 may be returned to the heat recovery steam generator 60.

[0082] In some embodiments, as shown in Figures 9, 10, 14, and 15, for example, the heat utilization facility 18 includes a carbon dioxide recovery facility 30. The carbon dioxide recovery facility 30 includes an absorption unit 32 (absorption tower) for absorbing carbon dioxide in the gas using an absorption liquid containing an absorbent, and a regeneration unit 36 ​​(regeneration tower) for heating and regenerating the absorption liquid that has absorbed the carbon dioxide. The absorption unit 32 is configured to be supplied with the heat source medium gas discharged from the first heat exchanger 2.

[0083] The absorbing section 32 is configured to bring the gas discharged from the first heat exchanger 2 into contact with an absorbing liquid, and to cause the absorbing liquid to absorb carbon dioxide in the gas. The absorbing liquid that has absorbed carbon dioxide (rich liquid having a relatively high carbon dioxide content) is stored at the bottom of the absorbing section 32 and is guided to the regenerating section 36 via a rich liquid line 34. The gas that has come into contact with the absorbing liquid may be discharged to the outside via a chimney 33.

[0084] The regeneration section 36 heats the absorbing liquid (rich liquid) from the absorbing section 32 to release carbon dioxide from the absorbing liquid. The carbon dioxide gas released from the absorbing liquid is taken out of the regeneration section 36 via a CO2 gas line 44 and used for EOR (Enhanced Oil Recovery), as a raw material for various chemicals and synthetic fuels, or stored and fixed to suppress global warming.

[0085] On the other hand, the absorption liquid regenerated in the regeneration section 36 (lean liquid having a relatively low carbon dioxide content) is stored in the bottom of the regeneration section 36 and returned to the absorption section 32 via a lean liquid line 38. The rich liquid flowing through the rich liquid line 34 may be heated in a heat exchanger 40 by the lean liquid flowing through the lean liquid line 38.

[0086] In some embodiments, the regeneration unit 36 ​​may be configured to heat the absorption liquid using the steam of the first medium generated in the high-pressure flash tank 6 and the low-pressure flash tank 8. For example, as shown in Figures 9, 10, 14, and 15, the regeneration unit 36 ​​may include a reboiler 42 configured to heat the absorption liquid by heat exchange with the steam of the first medium. That is, the medium to be heated in the heat utilization facility 18 (carbon dioxide recovery facility 30) of the heat recovery utilization system 1 according to this embodiment is the absorption liquid.

[0087] According to the above-described embodiment, the high-temperature, high-pressure steam of the first medium generated by a relatively small compressor power can be used to regenerate the absorbing liquid in the carbon dioxide recovery facility 30.

[0088] The type of carbon dioxide absorbent contained in the absorption liquid is not particularly limited, but for example, alkanolamines such as monoethanolamine and diethanolamine, and various aqueous alkali solutions other than amines such as sodium hydroxide, potassium hydroxide, and calcium hydroxide can be used.

[0089] In some embodiments, the carbon dioxide recovery facility 30 is configured to recover carbon dioxide contained in the heat source medium after the first medium is heated in the first heat exchanger 2.

[0090] 9 and 10, for example, the heat recovery and utilization system 1 includes a carbon dioxide-containing gas generation facility 51 configured to generate a carbon dioxide-containing gas. The first heat exchanger 2 is configured to heat a first medium flowing through the circulation line 4 by heat exchange with the carbon dioxide-containing gas as a heat source medium, and the carbon dioxide recovery facility 30 is configured to recover carbon dioxide contained in the carbon dioxide-containing gas after the first medium is heated by the first heat exchanger 2. In order to recover carbon dioxide from a carbon dioxide-containing gas in the carbon dioxide recovery facility 30, it is necessary to cool the carbon dioxide-containing gas to a low temperature (for example, 40°C). At that time, low-temperature cooling waste heat is generated, and effective utilization becomes an issue. Since the cooling waste heat is low temperature, it is difficult to solve this issue. On the other hand, in the carbon dioxide recovery facility 30, a large amount of heat is consumed in the reboiler 42 that heats the absorption liquid, and supplying it becomes an issue. Here, the heat required in the reboiler 42 needs to be at a higher temperature (for example, 140°C) than the waste heat generated when cooling the carbon dioxide-containing gas, and the heat required in the reboiler 42 cannot be directly supplied using the waste heat generated when cooling the carbon dioxide-containing gas. By using the present invention, it is possible to effectively utilize the low-temperature waste heat generated when cooling the carbon dioxide-containing gas by using a relatively small compression power, and to supply the heat required in the reboiler 42, thereby solving the above issue, improving energy utilization efficiency, and recovering carbon dioxide with less energy consumption.

[0091] Examples of combinations of the carbon dioxide-containing gas generation equipment 51 and the carbon dioxide-containing gas to be discharged include a prime mover (gas turbine, gas engine, SOFC, etc.) and its exhaust gas, a boiler and its exhaust gas, a reformer and its reformed gas, a blast furnace and a blast furnace by-product gas, a heat treatment furnace that burns fuel and its exhaust gas, a ceramic kiln and its exhaust gas, a waste incinerator and its exhaust gas, etc. The above-mentioned reformer may include a furnace that performs, for example, steam methane reforming (SMR), autothermal reforming (ATR), etc.

[0092] In one embodiment, as shown, for example, in Figures 14 and 15, a carbon dioxide-containing gas generation facility 51 includes a combustion device 82 configured to generate a flue gas containing carbon dioxide by combusting a fuel.

[0093] The combustion device 82 may include, for example, a prime mover (gas turbine, gas engine, SOFC, etc.), various heat treatment furnaces, and the like.

[0094] 15 , the combustion system 82 includes a compressor 90 for compressing air, a combustor 92 for combusting fuel with the compressed air, and a turbine 94 configured to be driven by combustion gases generated in the combustor 92. The gas turbine 88 may be configured to drive a generator 96.

[0095] In some embodiments, for example as shown in Figures 14 and 15, the heat recovery and utilization system 1 includes a fuel gas generation facility 80 configured to generate a carbon-containing fuel gas, and the combustion device 82 is configured to use the carbon-containing fuel gas generated in the fuel gas generation facility 80 as fuel.

[0096] In the exemplary embodiment shown in Figure 15, the fuel gas generation facility 80 includes a steel plant 84 including a blast furnace. In the blast furnace, gases including carbon monoxide and carbon dioxide are generated and exhausted due to a reduction reaction of iron ore. The combustion device 82 (a gas turbine 88 in the example shown in Figure 15) is configured to use the carbon-containing fuel gas (such as carbon monoxide) exhausted from the steel plant 84 as fuel.

[0097] According to the above-described embodiment, the carbon-containing fuel gas generated in the fuel gas generation equipment 80 (e.g., the steelmaking equipment 84) can be used as fuel in the combustion device 82 (e.g., the gas turbine 88), and the carbon dioxide contained in the combustion exhaust gas (heat source medium) from the combustion device 82 is recovered in the carbon dioxide recovery equipment 30, and the steam of the first medium generated using the heat recovered from the combustion exhaust gas (heat source medium) can be used to regenerate the absorbent in the carbon dioxide recovery equipment 30.

[0098] The contents described in each of the above embodiments can be understood, for example, as follows.

[0099] [1] At least one embodiment of the heat recovery and utilization system (1) of the present invention comprises: a circulation line (4) through which the first medium circulates; a first heat exchanger (2) for heating the first medium in a liquid state flowing through the circulation line by heat exchange with a heat source medium; a high-pressure flash tank (6) provided in the circulation line and into which the first medium in a liquid state heated by the first heat exchanger is introduced; At least one low-pressure flash tank (8) provided in the circulation line and into which the first medium in a liquid state is guided from the high-pressure flash tank; a steam supply line (10) for guiding the steam of the first medium generated in the high-pressure flash tank to a heat utilization facility; a vapor merging line (12) for merging the vapor of the first medium generated in the at least one low-pressure flash tank with the vapor of the first medium from the high-pressure flash tank flowing through the vapor supply line; at least one low-pressure stage compressor (14) provided in the vapor merging line for pressurizing the vapor of the first medium from the at least one low-pressure flash tank; Equipped with.

[0100] According to the above-mentioned configuration [1], the first medium heated by heat exchange with the heat source medium in the first heat exchanger is flashed in the high-pressure flash tank and the low-pressure flash tank in sequence to generate steam (flash steam). Therefore, compared to the case where only one flash tank is provided, steam can be extracted until the first medium becomes lower in temperature. In addition, since the relatively low-temperature and low-pressure steam generated in the low-pressure flash tank is compressed by the compressor, the compressed steam can be used as high-temperature and high-pressure steam together with the steam generated in the high-pressure flash tank. Therefore, according to the above-mentioned configuration [1], a larger amount of high-temperature and high-pressure steam can be generated and used with a relatively small compressor power. In other words, according to the above-mentioned configuration [1], a larger amount of high-temperature and high-pressure steam can be used while efficiently recovering heat.

[0101] [2] In some embodiments, in the configuration of [1] above, The heat recovery and utilization system includes: In the first heat exchanger, the first medium and the heat source medium are configured to exchange heat without a phase change.

[0102] According to the configuration [2] above, since the first medium and the heat source medium exchange heat in the first heat exchanger without undergoing a phase change, the temperature difference between the heat source medium and the first medium can be reduced compared to a case where either the first medium or the heat source medium does not undergo a phase change and the other undergoes a phase change during heat exchange, thereby improving the heat utilization efficiency of the heat source medium.

[0103] [3] In some embodiments, in the configuration of [1] or [2] above, The heat recovery and utilization system includes: The heat utilization facility (18) is configured to receive the steam of the first medium from the steam supply line and utilize it as a heat source.

[0104] According to the configuration [3] above, the heat utilization equipment receives steam of the first medium from the steam supply line, so that the heat utilization equipment can use a larger amount of high-temperature, high-pressure steam as a heat source while efficiently recovering heat as described in [1] above.

[0105] [4] In some embodiments, in the configuration of [3] above, The heat utilization facility is configured to heat a medium to be heated by heat exchange with the first medium.

[0106] According to the configuration [4] above, the heated medium is heated by heat exchange with the first medium in the heat utilization equipment. Therefore, while efficiently recovering heat as described in [1] above, the heated medium can be heated in the heat utilization equipment using a larger amount of high-temperature, high-pressure steam as a heat source.

[0107] [5] In some embodiments, in the configuration of [4] above, The heat recovery and utilization system includes: The heat utilization facility is configured so that the medium to be heated and the first medium exchange heat while undergoing a phase change.

[0108] According to the configuration of [5] above, since the heated medium and the first medium are configured to exchange heat while undergoing phase change in the heat utilization equipment, the temperature difference between the first medium and the heated medium can be reduced compared to a case where either the heated medium or the first medium undergoes phase change while the other does not undergo phase change during heat exchange. Therefore, the heat utilization efficiency of the heat source medium can be improved.

[0109] [6] In some embodiments, in any of the configurations [3] to [5] above, The heat recovery and utilization system includes: a return line (16) for returning the first medium used as a heat source in the heat utilization facility to the circulation line; The return line is configured to return the first medium to a position in the circulation line downstream of the high-pressure flash tank and upstream of a most downstream low-pressure flash tank that is located at the most downstream position among the at least one low-pressure flash tank, or to the most downstream low-pressure flash tank.

[0110] In the configuration [6] above, the first medium used as a heat source in the heat utilization equipment is returned to the circulation line and flashed again in the low-pressure flash tank to generate steam (flash steam), which is then pressurized by the low-pressure compressor and supplied to the heat utilization equipment. That is, according to the configuration [6] above, the relatively high-temperature, high-pressure first medium after being used as a heat source in the heat utilization equipment is led to the low-pressure flash tank to further utilize the heat remaining in the first medium. As a result, the temperature of the first medium at the inlet of the first heat exchanger is lowered compared to when the first medium at the outlet of the heat utilization equipment is sent directly to the first heat exchanger, so that the heat of the heat source medium can be recovered until it becomes lower in temperature. Therefore, according to the configuration [6] above, it is possible to utilize more high-temperature, high-pressure steam while recovering heat more efficiently.

[0111] [7] In some embodiments, in any one of the configurations [1] to [6] above, The heat recovery and utilization system includes: The steam supply system further includes a high-pressure stage compressor (20) provided in the steam supply line for pressurizing the vapor of the first medium from the high-pressure flash tank.

[0112] According to the configuration [7] above, by pressurizing the relatively high temperature and pressure flash steam of the first medium generated in the high-pressure flash tank using the high-pressure stage compressor, it is possible to utilize steam with even higher temperature and pressure in the heat utilization equipment (for example, steam with a higher temperature than the temperature of the heat source medium in the first heat exchanger).

[0113] [8] In some embodiments, in the configuration of [7] above, The heat recovery and utilization system includes: The compressor further includes a cooling section (22) provided between the at least one low-pressure stage compressor and the high-pressure stage compressor for cooling the vapor of the first medium pressurized by the at least one low-pressure stage compressor.

[0114] According to the configuration of [8] above, the first medium vapor compressed in the low-pressure stage compressor is cooled in the cooling section before being introduced into the high-pressure stage compressor, so that the compressor power of the high-pressure stage compressor can be reduced. Therefore, more high-temperature, high-pressure vapor can be used while efficiently recovering heat.

[0115] [9] In some embodiments, in the configuration of [8] above, The cooling section is configured to spray the first medium in a liquid state from the circulation line into vapor of the first medium.

[0116] According to the configuration [9] above, by spraying the first medium in a liquid state from the circulation line, the vapor of the first medium compressed in the low-pressure stage compressor can be appropriately cooled.

[0117]

[10] In some embodiments, in the configuration of [8] above, The cooling unit is configured to cool the vapor of the first medium by heat exchange with the first medium in a liquid state from the circulation line.

[0118] According to the above configuration

[10] , the vapor of the first medium compressed in the low-pressure stage compressor can be appropriately cooled by heat exchange with the first medium in a liquid state from the circulation line.

[0119]

[11] In some embodiments, in the configuration of [8] above, The cooling section is configured to cool the vapor of the first medium by heat exchange with the first medium in a liquid state in the high-pressure flash tank.

[0120] According to the configuration

[11] above, the vapor of the first medium compressed in the low-pressure stage compressor is cooled by heat exchange with the first medium in a relatively high-temperature liquid state in the high-pressure flash tank, thereby making it possible to suppress the generation of liquid droplets at the inlet of the high-pressure stage compressor due to excessive cooling of the vapor of the first medium.

[0121]

[12] In some embodiments, in any one of the configurations [1] to

[11] above, The heat recovery and utilization system includes: a heat recovery boiler (60) including a duct (62) through which exhaust gas from an exhaust gas generating facility is guided, and at least one second heat exchanger (e.g., the above-mentioned evaporator 66a, superheater 66b, economizer 66c, evaporator 68a and / or superheater 68b) provided in the duct for heating a second medium by heat exchange with the exhaust gas to generate steam, The first heat exchanger is provided in the duct downstream of the at least one second heat exchanger in the flow of the exhaust gas, and is configured to heat the first medium by heat exchange with the exhaust gas as the heat source medium.

[0122] In the configuration of

[12] above, in the heat recovery boiler, in addition to generating steam of the second medium through heat exchange in the second heat exchanger using heat from the exhaust gas from the exhaust gas generation facility, the first medium heated through heat exchange with the exhaust gas whose temperature has been reduced by passing through the second heat exchanger can be introduced into the high-pressure flash tank and low-pressure flash tank to generate steam (flash steam). Thus, according to the configuration of

[12] above, it is possible to utilize more high-temperature, high-pressure steam while efficiently recovering heat.

[0123]

[13] In some embodiments, in the configuration of

[12] above, The heat recovery and utilization system includes: The circulation line is provided with a branch line (56A, 56B) that branches off from a portion downstream of the first heat exchanger and upstream of the high-pressure flash tank, for guiding a portion of the first medium flowing through the portion to any one of the at least one second heat exchanger as the second medium.

[0124] According to the configuration of

[13] above, a part of the first medium heated by heat exchange with the exhaust gas in the first heat exchanger can be guided to the second heat exchanger as the second medium via the branch line. That is, the first medium guided to the high-pressure flash tank and the low-pressure flash tank, and the second medium guided to the second heat exchanger can be heated by heat exchange with the relatively low-temperature exhaust gas in the first heat exchanger. Therefore, according to the configuration of

[13] above, it is possible to use more high-temperature, high-pressure steam while efficiently recovering heat.

[0125]

[14] In some embodiments, in the configuration of

[13] above, the at least one second heat exchanger includes a plurality of evaporators (66a, 68a) for generating vapors having different pressures; The branch line is configured to guide a portion of the first medium flowing through the portion of the circulation line to an evaporator (68a) that is located furthest downstream in the flow of the exhaust gas within the duct, among the multiple evaporators.

[0126] According to the configuration of

[14] above, a part of the first medium heated by heat exchange with the exhaust gas in the first heat exchanger can be guided as the second medium through the branch line to the evaporator located at the most downstream side in the duct. That is, the first medium guided to the high-pressure flash tank and the low-pressure flash tank, and the second medium guided to the above-mentioned evaporator can be heated by heat exchange with the relatively low-temperature exhaust gas in the first heat exchanger. Therefore, according to the configuration of

[14] above, it is possible to use more high-temperature, high-pressure steam while efficiently recovering heat.

[0127]

[15] In some embodiments, in any one of the configurations

[12] to

[14] above, The heat recovery and utilization system includes: The steam turbine (72) is configured to be driven by steam of the second medium generated in the heat recovery steam generator.

[0128] According to the configuration of

[15] above, in the heat recovery boiler, in addition to generating steam (steam of the second medium) for driving a steam turbine by heat exchange in the second heat exchanger using heat from the exhaust gas from the exhaust gas generation facility, the first medium heated by heat exchange with the exhaust gas whose temperature has been reduced by passing through the second heat exchanger can be introduced into the high-pressure flash tank and the low-pressure flash tank to generate steam (flash steam). Therefore, according to the configuration of

[15] above, it is possible to utilize more high-temperature, high-pressure steam while efficiently recovering heat.

[0129]

[16] In some embodiments, in the configuration of

[15] above, The heat recovery and utilization system includes: a turbine outlet line (76) through which the steam of the second medium is discharged from the steam turbine; The turbine exit line is connected to the steam supply line.

[0130] According to the configuration

[16] above, in addition to the steam (flash steam) generated in the high-pressure flash tank and the low-pressure flash tank, the steam discharged from the steam turbine is also supplied to the heat utilization equipment via the steam supply line, so that more high-temperature, high-pressure steam can be utilized while efficiently recovering heat.

[0131]

[17] In some embodiments, in any one of the configurations [1] to

[16] above, The heat recovery and utilization system includes: The carbon dioxide recovery system includes an absorption section (32) for absorbing carbon dioxide in a gas using an absorption liquid containing an absorbent, and a regeneration section (36) for heating and regenerating the absorption liquid that has absorbed carbon dioxide, The steam supply line is configured to supply steam of the first medium to the regenerator serving as the heat utilization facility.

[0132] According to the configuration of

[17] above, the high-temperature, high-pressure steam of the first medium generated by a relatively small compressor power can be used to regenerate the absorbing liquid in the carbon dioxide recovery facility.

[0133]

[18] In some embodiments, in the configuration of

[17] above, The heat source medium includes carbon dioxide, The carbon dioxide recovery facility is configured to recover carbon dioxide contained in the heat source medium after the first medium is heated in the first heat exchanger.

[0134] According to the configuration

[18] above, the carbon dioxide contained in the heat source medium is recovered in the carbon dioxide recovery equipment, and the steam of the first medium generated using the heat recovered from the heat source medium can be used to regenerate the absorbent in the carbon dioxide recovery equipment.

[0135]

[19] In some embodiments, in the configuration of

[17] or

[18] above, The heat recovery and utilization system includes: A carbon dioxide-containing gas generating facility (51) configured to generate a carbon dioxide-containing gas, The first heat exchanger is configured to heat the first medium by heat exchange with the carbon dioxide-containing gas as the heat source medium, The carbon dioxide recovery facility is configured to recover carbon dioxide contained in the carbon dioxide-containing gas after the first medium is heated in the first heat exchanger.

[0136] According to the configuration

[19] above, in the carbon dioxide recovery equipment, carbon dioxide contained in the carbon dioxide-containing gas (heat source medium) from the carbon dioxide-containing gas generation equipment is recovered, and the steam of the first medium generated using the heat recovered from the carbon dioxide-containing gas (heat source medium) can be used to regenerate the absorbent in the carbon dioxide recovery equipment.

[0137]

[20] In some embodiments, in the configuration of

[19] above, The carbon dioxide-containing gas generation facility includes a combustion device (82) configured to combust a fuel to generate a flue gas that includes carbon dioxide.

[0138] According to the configuration

[20] above, carbon dioxide contained in the combustion exhaust gas (heat source medium) from the combustion device can be recovered in the carbon dioxide recovery equipment, and the steam of the first medium generated using the heat recovered from the combustion exhaust gas (heat source medium) can be used to regenerate the absorbent in the carbon dioxide recovery equipment.

[0139]

[21] In some embodiments, in the configuration of

[20] above, The heat recovery and utilization system includes: a fuel gas generation facility (80) configured to generate a carbon-containing fuel gas; The combustion device is configured to use the carbon-containing fuel gas produced in the fuel gas production facility as the fuel.

[0140] According to the configuration

[21] above, the carbon-containing fuel gas generated in the fuel gas generation equipment can be used as fuel in the combustion equipment, and the carbon dioxide contained in the combustion exhaust gas (heat source medium) from the combustion equipment can be recovered in the carbon dioxide recovery equipment, and the steam of the first medium generated using the heat recovered from the combustion exhaust gas (heat source medium) can be used to regenerate the absorbent in the carbon dioxide recovery equipment.

[0141]

[22] In some embodiments, in the configuration of

[21] above, The fuel gas generating facility includes a steelmaking facility (84) including a blast furnace, The combustion device is configured to use the carbon-containing fuel gas discharged from the steel making facility as the fuel.

[0142] According to the configuration

[22] above, the carbon-containing fuel gas generated in the steelmaking facility can be used as fuel in the combustion device, and the carbon dioxide contained in the combustion exhaust gas (heat source medium) from the combustion device can be recovered in the carbon dioxide capture facility. At the same time, the steam of the first medium generated using the heat recovered from the combustion exhaust gas (heat source medium) can be used to regenerate the absorbent in the carbon dioxide capture facility.

[0143] Although the embodiments of the present invention have been described above, the present invention is not limited to the above-described embodiments, and also includes modifications to the above-described embodiments and appropriate combinations of these modifications.

[0144] In this specification, expressions expressing relative or absolute configuration, such as "in a certain direction," "along a certain direction," "parallel," "orthogonal," "center," "concentric," or "coaxial," do not only strictly represent such a configuration, but also represent a state in which there is a relative displacement with a tolerance or an angle or distance to the extent that the same function is obtained. For example, expressions indicating that things are in an equal state, such as "identical," "equal," and "homogeneous," not only indicate a state of strict equality, but also indicate a state in which there is a tolerance or a difference to the extent that the same function is obtained. Furthermore, in this specification, expressions describing shapes such as a rectangular shape or a cylindrical shape do not only refer to shapes such as a rectangular shape or a cylindrical shape in the strict geometric sense, but also refer to shapes that include uneven portions, chamfered portions, etc., to the extent that the same effect is obtained. In addition, in this specification, the expressions "comprise," "include," or "have" a certain element are not exclusive expressions that exclude the presence of other elements. [Explanation of symbols]

[0145] 1. Heat recovery and utilization system 2 1st heat exchanger 4 Circulation Line 4a connection line 4b Connection line 5 Pressure Reducing Valve 6. High-pressure flash tank 7a Pressure reducing valve 7b Pressure reducing valve 8. Low Pressure Flash Tank 9. Pump 10 Steam supply line 12 Merging Line 14 Low pressure stage compressor 16 Return Line 18 Heat utilization equipment 20 High pressure stage compressor 22 Cooling section 24 Spray 25 Coolant Line 26 Heat exchange section 28 Cooling section 30 Carbon dioxide capture facility 32 Absorption section 33 Chimney 34 Rich Fluid Line 36 Playback Department 38 Lean Fluid Line 40 Heat exchanger 42 Reboiler 44 CO2 gas line 50 Exhaust gas generating equipment 51 Carbon dioxide-containing gas generating equipment 52 Exhaust gas introduction line 54 Discharge Line 56 Branch Line 56A Branch Line 56B Branch Line 57A Valve 57B Valve 58 Steam Utilization Facilities 60 Waste heat recovery boiler 62 Duct 64 Economizer 66a Evaporator 66b Superheater 66c economizer 67 Steam Drum 68a Evaporator 68b Superheater 72 Steam Turbine 74 Generator 76 Turbine Exit Line 77 Condenser 80 Fuel gas generation equipment 82 Combustion equipment 84 Steelmaking Equipment 88 Gas Turbine 90 Compressor 92 Combustor 94 Turbine 96 Generator 100 Heat recovery and utilization system 106 Flash Tank J confluence

Claims

1. a circulation line through which the first medium circulates; a first heat exchanger for heating the first medium in a liquid state flowing through the circulation line by heat exchange with a heat source medium; a high-pressure flash tank provided in the circulation line and into which the first medium in a liquid state heated by the first heat exchanger is introduced; at least one low-pressure flash tank provided in the circulation line and into which the first medium in a liquid state is guided from the high-pressure flash tank; a steam supply line for guiding the steam of the first medium generated in the high-pressure flash tank to a heat utilization facility; a vapor merging line for merging the vapor of the first medium generated in the at least one low-pressure flash tank with the vapor of the first medium from the high-pressure flash tank flowing through the vapor supply line; at least one low-pressure stage compressor provided in the vapor merging line for pressurizing the vapor of the first medium from the at least one low-pressure flash tank; A heat recovery and utilization system.

2. In the first heat exchanger, the first medium and the heat source medium are configured to exchange heat without changing phase. The heat recovery and utilization system according to claim 1 .

3. a heat utilization facility configured to receive the steam of the first medium from the steam supply line and utilize it as a heat source; The heat recovery and utilization system according to claim 1 or 2.

4. The heat utilization equipment is configured to heat a medium to be heated by heat exchange with the first medium. The heat recovery and utilization system according to claim 3.

5. In the heat utilization equipment, the heated medium and the first medium are configured to exchange heat while undergoing a phase change. The heat recovery and utilization system according to claim 4.

6. a return line for returning the first medium used as a heat source in the heat utilization facility to the circulation line, The return line is configured to return the first medium to a position in the circulation line downstream of the high-pressure flash tank and upstream of a most downstream low-pressure flash tank located at the most downstream side of the at least one low-pressure flash tank, or to the most downstream low-pressure flash tank. The heat recovery and utilization system according to claim 3.

7. a high-pressure stage compressor provided in the steam supply line for pressurizing the steam of the first medium from the high-pressure flash tank; The heat recovery and utilization system according to claim 1 or 2.

8. a cooling unit provided between the at least one low-pressure stage compressor and the high-pressure stage compressor for cooling the vapor of the first medium pressurized by the at least one low-pressure stage compressor; The heat recovery and utilization system according to claim 7.

9. The cooling unit is configured to spray the first medium in a liquid state from the circulation line into the vapor of the first medium. The heat recovery and utilization system according to claim 8.

10. The cooling unit is configured to cool the vapor of the first medium by heat exchange with the first medium in a liquid state from the circulation line. The heat recovery and utilization system according to claim 8.

11. The cooling unit is configured to cool the vapor of the first medium by heat exchange with the first medium in a liquid state in the high-pressure flash tank. The heat recovery and utilization system according to claim 8.

12. a heat recovery boiler including a duct through which exhaust gas from an exhaust gas generating facility is guided, and at least one second heat exchanger provided in the duct for heating a second medium by heat exchange with the exhaust gas to generate steam; The first heat exchanger is provided in the duct downstream of the at least one second heat exchanger in the flow of the exhaust gas, and is configured to heat the first medium by heat exchange with the exhaust gas serving as the heat source medium. The heat recovery and utilization system according to claim 1 or 2.

13. a branch line that branches off from a portion of the circulation line that is downstream of the first heat exchanger and upstream of the high-pressure flash tank, and that guides a portion of the first medium flowing through the portion to any one of the at least one second heat exchangers as the second medium; The heat recovery and utilization system according to claim 12.

14. the at least one second heat exchanger includes a plurality of evaporators for producing vapors at different pressures; The branch line is configured to guide a portion of the first medium flowing through the portion of the circulation line to an evaporator that is disposed at the most downstream side in the flow of the exhaust gas within the duct, among the plurality of evaporators. The heat recovery and utilization system according to claim 13.

15. a steam turbine configured to be driven by the steam of the second medium generated in the heat recovery boiler; The heat recovery and utilization system according to claim 12.

16. a turbine outlet line through which the steam of the second medium is discharged from the steam turbine; The turbine outlet line is connected to the steam supply line. The heat recovery and utilization system according to claim 15.

17. The carbon dioxide recovery system includes an absorption unit for absorbing carbon dioxide in a gas using an absorption liquid containing an absorbent, and a regeneration unit for heating and regenerating the absorption liquid that has absorbed carbon dioxide, The steam supply line is configured to supply steam of the first medium to the regenerator as the heat utilization equipment. The heat recovery and utilization system according to claim 1 or 2.

18. The heat source medium includes carbon dioxide, The carbon dioxide recovery facility is configured to recover carbon dioxide contained in the heat source medium after the first medium is heated in the first heat exchanger. The heat recovery and utilization system according to claim 17.

19. A carbon dioxide-containing gas generating facility configured to generate a carbon dioxide-containing gas, The first heat exchanger is configured to heat the first medium by heat exchange with the carbon dioxide-containing gas as the heat source medium, The carbon dioxide recovery facility is configured to recover carbon dioxide contained in the carbon dioxide-containing gas after the first medium is heated by the first heat exchanger. The heat recovery and utilization system according to claim 17.

20. The carbon dioxide-containing gas generation facility includes a combustion device configured to generate a combustion exhaust gas containing carbon dioxide by burning a fuel. The heat recovery and utilization system according to claim 19.

21. a fuel gas generation facility configured to generate a carbon-containing fuel gas; The combustion device is configured to use the carbon-containing fuel gas generated in the fuel gas generation facility as the fuel. The heat recovery and utilization system according to claim 20.

22. The fuel gas generating facility includes a steelmaking facility including a blast furnace, The combustion device is configured to use the carbon-containing fuel gas discharged from the steelmaking facility as the fuel. The heat recovery and utilization system according to claim 21.

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