Carbon dioxide separation system and air conditioning system equipped therewith

Abstract

It suppresses the decrease in carbon dioxide separation efficiency. [Solution] The carbon dioxide separation system 300 includes a cooling unit 303 for lowering the temperature of exhaust gas generated from an internal combustion engine, a heating unit 307 located downstream of the cooling unit 303 for raising the temperature of exhaust gas, and a separation element 400 located downstream of the heating unit 307 for separating carbon dioxide from the exhaust gas. The heating unit 307 also suppresses condensation in the separation element 400 by lowering the relative humidity of the exhaust gas. This suppresses a decrease in the carbon dioxide separation efficiency in the separation element 400.

Description

[Technical Field]

[0001] The present invention relates to a carbon dioxide separation system and an air conditioner including the same. [Background Art]

[0002] In recent years, demand for techniques for recovering carbon dioxide has been increasing in various facilities that emit carbon dioxide such as factories and power plants.

[0003] For example, Patent Document 1 discloses a technique for selectively recovering carbon dioxide from a gas containing carbon dioxide by a chemical absorption method.

[0004] Further, Patent Document 2 discloses a technique for recovering carbon dioxide by a membrane separation method. Specifically, a configuration is disclosed in which a gas mixture containing a large amount of carbon dioxide is circulated through one of two flow paths formed with a carbon dioxide separation membrane interposed therebetween, and a steam sweep gas is circulated through the other.

[0005] The carbon dioxide separation technique based on the membrane separation method as disclosed in Patent Document 2 can separate carbon dioxide with less energy compared to the chemically absorbed carbon dioxide separation technique as disclosed in Patent Document 1. [Prior Art Documents] [Patent Documents]

[0006] [Patent Document 1] Japanese Unexamined Patent Application Publication No. 2004-292298 [Patent Document 2] Japanese National Publication of International Patent Application No. 2015-536814 [Summary of the Invention] [Problem to be Solved by the Invention]

[0007] The operating temperature range of carbon dioxide separation membranes used in membrane separation methods varies greatly depending on the type (composition) of the membrane. Therefore, in membrane separation methods, it is necessary to adjust the temperature of the exhaust gas supplied to the carbon dioxide separation membrane so that it falls within the operating temperature range of the membrane.

[0008] For example, in Patent Document 2, exhaust gas is cooled by supplying water vapor sweep gas to a carbon dioxide separation membrane.

[0009] However, in this type of cooling system, two gases with different temperatures flow with the carbon dioxide separation membrane as the boundary, causing condensation on the membrane. In other words, the contact area between the membrane and the exhaust gas is reduced, which may decrease the efficiency of carbon dioxide separation.

[0010] This invention was made in view of the above problems and provides a carbon dioxide separation system that can suppress the decrease in carbon dioxide separation efficiency. [Means for solving the problem]

[0011] The carbon dioxide separation system according to the present invention comprises a cooling section for lowering the temperature of exhaust gas generated from an internal combustion engine, a heating section located downstream of the cooling section for raising the temperature of the exhaust gas, and a separation membrane located downstream of the heating section for separating carbon dioxide from the exhaust gas. The heating section suppresses condensation on the separation membrane by lowering the relative humidity of the exhaust gas. [Effects of the Invention]

[0012] The present invention provides a carbon dioxide separation system capable of suppressing the reduction in carbon dioxide separation efficiency, and an air conditioning system using the same. [Brief explanation of the drawing]

[0013] [Figure 1] Figure 1 is a schematic diagram showing the general configuration of an air conditioning system. [Figure 2]Figure 2 is a schematic diagram showing the general configuration of a carbon dioxide separation system. [Figure 3] Figure 3 is a schematic diagram showing the general structure of the separation membrane. [Figure 4] Figure 4 is a schematic diagram showing the external structure of the separation membrane. [Figure 5] Figure 5 is a flowchart showing the flow of the dehumidification process. [Figure 6] Figure 6 is a flowchart showing the flow of the cooling process. [Figure 7] Figure 7 is a flowchart showing the flow of the heating process. [Figure 8] Figure 8 is a schematic diagram showing the temperature change of exhaust gas. [Figure 9] Figure 9 is a schematic diagram showing the exhaust gas flow path in a modified example. [Modes for carrying out the invention]

[0014] Embodiments for implementing this disclosure will be described with reference to the accompanying drawings. The embodiments described below all represent preferred specific examples of this disclosure. Therefore, the numerical values, shapes, materials, components, arrangement and connection configurations of components, as well as steps (processes) and the order of steps shown in the embodiments are examples and are not intended to limit this disclosure. Accordingly, components in the embodiments that are not described in the independent claims representing the highest-level concepts of this disclosure will be described as arbitrary components. In addition, substantially identical components are denoted by the same reference numerals in each figure, and redundant explanations are omitted or simplified.

[0015] Furthermore, while terms including ordinal numbers such as "first" and "second" are used to describe various components, these terms are used solely to distinguish one component from others, and do not limit the components themselves. (Embodiment 1) First, the air conditioning system 1 according to Embodiment 1 will be described with reference to Figure 1. Figure 1 is a schematic diagram showing the general configuration of the air conditioning system 1.

[0016] The air conditioner 1 is a so-called gas-type air conditioner in which a compressor 101 that compresses refrigerant vapor is driven by a gas engine 102. The air conditioner 1 includes an outdoor unit 100, an indoor unit 200, and a refrigerant pipe 2. The refrigerant pipe 2 is provided across the outdoor unit 100 and the indoor unit 200.

[0017] The indoor unit 200 includes an indoor heat exchanger 201, an indoor fan 202, and a pressure reducing device 203.

[0018] The indoor heat exchanger 201 performs heat exchange between indoor air and refrigerant. Specifically, in a cooling operation, the refrigerant absorbs heat from indoor air, and in a heating operation, the refrigerant releases heat to indoor air.

[0019] The indoor fan 202 generates an airflow passing through the indoor heat exchanger 201, thereby promoting heat exchange between the refrigerant and indoor air.

[0020] The pressure reducing device 203 adjusts the pressure and flow rate of the refrigerant, and sends the refrigerant to the indoor heat exchanger 201.

[0021] The outdoor unit 100 includes the compressor 101, the gas engine 102, an oil separator 1 03, a four-way valve 110, an outdoor heat exchanger 105, an accumulator 109, an outdoor fan 104, a pressure reducing device 107, a control unit 70, and a carbon dioxide separation system 300.

[0022] The compressor 101 is connected to the refrigerant pipe 2 and the gas engine 102. The compressor 101 is a device that compresses the refrigerant flowing inside the refrigerant pipe 2 and changes the refrigerant into a high-temperature and high-pressure state. The compressor 101 is driven by the gas engine 102. The compressor 101 is not particularly limited in type as long as it can be used in a gas-type air conditioner. For example, general-purpose compressors such as rotary type or piston type can be used.

[0023] The gas engine 102 is connected to the compressor 101. The gas engine 102 is a so-called internal combustion engine that drives the compressor 101 by burning gaseous fuel such as city gas or natural gas. The exhaust gas produced by the combustion of fuel in the gas engine 102 is treated in a carbon dioxide separation system 300 before being released into the atmosphere, but the details will be described later.

[0024] The oil separator 103 is connected to the compressor 101 and the four-way valve 110. The oil separator 103 separates the refrigerant oil contained in the refrigerant flowing through the refrigerant piping 2. The separated refrigerant oil is returned to the compressor 101 via an oil return pipe (not shown).

[0025] The four-way valve 110 is used to switch between cooling and heating operation, and Figure 1 shows the flow of refrigerant during cooling operation (black solid arrow in Figure 1).

[0026] The outdoor heat exchanger 105 performs heat exchange between the refrigerant and the outside air. Specifically, in cooling operation, the refrigerant releases heat to the outside air, and in heating operation, the refrigerant absorbs heat from the outside air.

[0027] The accumulator 109 separates the refrigerant into gaseous refrigerant and liquid refrigerant, and sends only the gaseous refrigerant to the compressor 101.

[0028] The outdoor fan 104 promotes heat exchange between the air and the refrigerant by generating an airflow that passes through the outdoor heat exchanger 105.

[0029] The pressure reducing device 107 adjusts the pressure and flow rate of the refrigerant and sends it to the outdoor heat exchanger 105.

[0030] The control unit 70 controls the flow rate of exhaust gas circulating through the bypass channel 360 by controlling the flow rate control means 350 (see Figure 2), which will be described later, thereby suppressing a decrease in the carbon dioxide separation efficiency in the carbon dioxide separation system 300. Details will be described later. The control unit 70 is connected to each component of the air conditioning system 1 (each fan, carbon dioxide separation system 300, etc.) via wired or wireless means so as to be able to communicate. The control unit 70 is a so-called computer that stores and executes programmed processes.

[0031] The carbon dioxide separation system 300 is a mechanism for selectively separating carbon dioxide from exhaust gas containing carbon dioxide generated from the gas engine 102.

[0032] Next, the configuration of the carbon dioxide separation system 300 will be explained using Figure 2. Figure 2 is a schematic diagram showing the general configuration of the carbon dioxide separation system 300.

[0033] The carbon dioxide separation system 300 is a mechanism that selectively separates carbon dioxide from exhaust gas using a separation element 400. Furthermore, the carbon dioxide separation system 300 in this disclosure is By suppressing condensation in the separation element 400, the decrease in separation efficiency is suppressed.

[0034] The carbon dioxide separation system 300 comprises a cooling unit 303, a cooling water supply unit 330, a heating unit 307, a separation element 400, and a muffler 309.

[0035] The cooling unit 303 is a so-called heat exchanger that dehumidifies exhaust gas A2 supplied from the gas engine 102 by cooling it. In other words, the cooling unit 303 lowers the temperature of exhaust gas A2 generated from the internal combustion engine and condenses it, thereby lowering the absolute humidity of exhaust gas A2. More specifically, the cooling unit 303 lowers the temperature of exhaust gas A2 to a range where the temperature of exhaust gas A2 is below the operating temperature Tlim (e.g., 60°C) of the separation element 400. In other words, the exhaust gas B downstream of the cooling unit 303 has a lower temperature and absolute humidity than the exhaust gas A2 upstream of the cooling unit 303.

[0036] The cooling unit 303 lowers the temperature of the exhaust gas A2 by exchanging heat between the cooling water supplied from the cooling water supply unit 330 and the exhaust gas. In other words, the cooling unit 303 can be any heat exchanger in which two fluids can exchange heat with each other without mixing, and there are no particular limitations on its type. As the cooling unit 303, for example, a so-called plate heat exchanger can be used, in which iron plates are stacked with predetermined intervals in between, and the exhaust gas A2 flows through the gaps on the surface side of the iron plates, and the cooling water flows through the gaps on the back side.

[0037] The cooling water supply unit 330 cools the exhaust gas A2 by supplying cooling water to the cooling unit 303. The cooling water supply unit 330 can utilize a general-purpose radiator used in typical air conditioning systems. The cooling water supply unit 330 generates cooling water by air cooling, for example, by an outdoor fan 104. Alternatively, the cooling water supply unit 330 can also utilize a so-called absorption chiller, which generates cooling water by utilizing the heat of vaporization when water (natural refrigerant) evaporates. The cooling water supply unit 330 comprises a cooling water pump 333 and a reservoir tank 335.

[0038] The cooling water pump 333 is installed in a flow path connecting the cooling water supply unit 330 and the cooling unit 303, and adjusts the flow rate of cooling water supplied to the cooling unit 303. More specifically, the cooling water pump 333 increases the amount of cooling water supplied to the cooling unit 303 when the cooling of the exhaust gas A2 is insufficient.

[0039] The reservoir tank 335 is provided to regulate the amount of coolant supplied to the coolant supply unit 330. The reservoir tank 335 replenishes the coolant when the amount of coolant in the coolant supply unit 330 becomes insufficient. In other words, the reservoir tank 335 stores any excess coolant.

[0040] The heating unit 307 is a so-called heat exchanger that reduces the relative humidity of exhaust gas B supplied from the cooling unit 303 by heating the exhaust gas B. In other words, the heating unit 307 is located downstream of the cooling unit 303 and reduces the relative humidity of exhaust gas B by raising its temperature, thereby suppressing condensation on the separation element 400. More specifically, the heating unit 307 raises the temperature of exhaust gas B in a range where the temperature of exhaust gas C downstream of the heating unit 307 is lower than the temperature of exhaust gas A2 upstream of the cooling unit 303. In other words, the heating unit 307 raises the temperature of exhaust gas B in a range where the temperature of exhaust gas C downstream of the heating unit 307 is below the service life temperature Tlim (e.g., 60°C) of the separation element 400. In this embodiment, the heating section 307 raises the temperature of the exhaust gas B flowing through the heating section 307 by performing heat exchange between the exhaust gas S flowing through the bypass channel 360a and the exhaust gas B that has flowed through the cooling section 303. For example, a plate heat exchanger can be used as the heating section 307.

[0041] The separation element 400 is located downstream of the heating section 307 and separates from exhaust gas C containing carbon dioxide. The carbon dioxide is selectively separated by the separation element 400. The carbon dioxide separated by the separation element 400 is sent to the carbon dioxide supply destination 308, and the exhaust gas D from which the carbon dioxide has been removed is sent to the muffler 309. The detailed configuration of the separation element 400 will be described later.

[0042] The carbon dioxide supply destination 308 is for storing or utilizing carbon dioxide. The carbon dioxide supply destination 308 may be, for example, a tank for storing carbon dioxide, or a methanation device that produces methane from carbon dioxide and hydrogen.

[0043] The muffler 309 reduces noise caused by the operation of the gas engine 102 and the emission of exhaust gases. The muffler 309 may include a catalyst (not shown). The catalyst oxidizes and reduces harmful substances such as carbon monoxide contained in the exhaust gas. In other words, the catalyst oxidizes carbon monoxide and converts it into carbon dioxide. Known technologies such as a three-way catalyst can be applied as the catalyst. The carbon dioxide separation system 300 further comprises a first channel 370a, a first bypass channel 360a, a second bypass channel 360b, a second channel 370b, a third channel 370c, a fourth channel 370d, and a fifth channel 370e.

[0044] The first flow path 370a is a flow path connecting the gas engine 102 and the cooling unit 303. At branching point P, the first flow path 370a divides the exhaust gas A1 discharged from the gas engine 102 into exhaust gas S that flows to the first bypass flow path 360a and exhaust gas A2 that flows to the cooling unit 303. The first flow path 370a also includes a first temperature measuring unit 320 and a first humidity measuring unit 325.

[0045] The first temperature measuring unit 320 is a so-called temperature sensor installed in the first flow path 370a and measures the temperature of the exhaust gas A2 flowing through the first flow path 370a. The first temperature measuring unit 320 can be any sensor capable of measuring the temperature of a gas, and various known temperature sensors can be used as the first temperature measuring unit 320. The first temperature measuring unit 320 is installed downstream of the branching point P.

[0046] The first humidity measuring unit 325 is a so-called humidity sensor installed in the first flow path 370a and measures the absolute humidity of the exhaust gas A2 flowing through the first flow path 370a. The first humidity measuring unit 325 can be any sensor capable of measuring the absolute humidity of a gas, and various known humidity sensors can be used as the first humidity measuring unit 325.

[0047] The first bypass passage 360a is a passage that connects the gas engine 102 and the heating section 307 via the branching point P of the first bypass passage 370a. In other words, the first bypass passage 360a connects the gas engine 102 and the heating section 307 without going through the cooling section 303. The first bypass passage 360a transfers thermal energy to the exhaust gas B that flows from the cooling section 303 into the heating section 307 by guiding the exhaust gas S to the heating section 307. This heats the exhaust gas B. The first bypass passage 360a is connected to the second bypass passage 360b via the heating section 307. The first bypass passage 360a may also be equipped with a blower to efficiently draw the exhaust gas A1 into the first bypass passage 360a. The first bypass passage 360a is also equipped with a flow rate control means 350.

[0048] The flow rate control means 350 adjusts the flow rate of exhaust gas S flowing from the first flow path 370a to the first bypass flow path 360a. More specifically, the flow rate control means 350 is a so-called damper that adjusts the flow rate of exhaust gas S flowing into the first bypass flow path 360a by rotating the tip portion 351 around the base portion 352. In this embodiment, the closed state is defined as the state in which the tip portion 351 is rotated so that the tip portion 351 and the base portion 352 are approximately in a straight line in the vertical direction. The closed state is the state in which exhaust gas A1 does not flow into the first bypass flow path 360a. This refers to the following. In this embodiment, "no inflow" has a design meaning and includes cases where exhaust gas leakage occurs that is unavoidable in manufacturing or due to deterioration over time. Furthermore, the state in which the tip portion 351 is located to the upper left or directly to the left of the base portion 352 is defined as the open state. The open state is a state in which exhaust gas A1 is intentionally allowed to flow into the first bypass passage 360a. The amount of exhaust gas A1 flowing into the first bypass passage 360a decreases as the tip portion 351 approaches directly above the base portion 352, and increases as the tip portion 351 approaches directly to the left of the base portion 352. Furthermore, the flow rate control means 350 is provided, for example, near the boundary between the first bypass passage 360a and the first passage 370a.

[0049] The second bypass passage 360b is a passage connecting the heating section 307 and the first passage 370a. The exhaust gas R, after heat exchange in the heating section 307, flows through the second bypass passage 360b. The second bypass passage 360b guides the exhaust gas R to the first passage 370a, where it is mixed with exhaust gas A1 or exhaust gas A2. The first bypass passage 360a and the second bypass passage 360b are collectively referred to as the "bypass passage 360".

[0050] The second flow path 370b is a flow path connecting the cooling section 303 and the heating section 307. More specifically, the second flow path 370b guides the exhaust gas B, whose temperature and absolute humidity have been reduced by the cooling section 303, to the heating section 307. The second flow path 370b includes a second temperature measuring section 323 and a second humidity measuring section 324.

[0051] The second temperature measuring unit 323 is a so-called temperature sensor installed in the second flow path 370b and measures the temperature of the exhaust gas B flowing through the second flow path 370b. The second temperature measuring unit 323 can be any sensor capable of measuring the temperature of a gas, and various known temperature sensors can be used as the second temperature measuring unit 323.

[0052] The second humidity measuring unit 324 is a so-called humidity sensor installed in the second flow path 370b and measures the absolute humidity of the exhaust gas B flowing through the second flow path 370b. The second humidity measuring unit 324 can be any sensor capable of measuring the absolute humidity of a gas, and various known humidity sensors can be used as the second humidity measuring unit 324.

[0053] The third channel 370c is a channel connecting the heating unit 307 and the separation element 400. More specifically, the third channel 370c guides exhaust gas C, whose temperature has been raised by the heating unit 307 to a range below the separation element 400's service temperature Tlim and whose relative humidity has decreased, to the separation element 400. The third channel 370c includes a third temperature measuring unit 321 and a third humidity measuring unit 322.

[0054] The third temperature measuring unit 321 is a so-called temperature sensor provided in the third flow path 370c, which measures the temperature of the exhaust gas C flowing through the third flow path 370c. In other words, the third temperature measuring unit 321 measures the temperature downstream of the heating unit 307. The third temperature measuring unit 321 can be any sensor capable of measuring the temperature of a gas, and various known temperature sensors can be used as the third temperature measuring unit 321. From the viewpoint of temperature control of the exhaust gas C flowing into the separation element 400, it is preferable that the third temperature measuring unit 321 be provided in the third flow path 370c at a position biased toward the separation element 400. More specifically, it is preferable that the third temperature measuring unit 321 be provided on the side of the separation element 400 that bisects the third flow path 370c. The third temperature measuring unit 321 is also referred to as the "temperature measuring unit".

[0055] The third humidity measuring unit 322 is a so-called humidity sensor installed in the third flow path 370c and measures the relative humidity of the exhaust gas C flowing through the third flow path 370c. The third humidity measuring unit 322 can be any sensor capable of measuring the relative humidity of a gas, and various known humidity sensors can be used as the third humidity measuring unit 322.

[0056] The fourth passage 370d is a passage connecting the separation element 400 and the muffler 309. More specifically, the exhaust gas D, whose carbon dioxide concentration has been reduced by the separation element 400, is guided to the muffler 309.

[0057] The fifth passage 370e is a passage through which exhaust gas E, from which harmful substances have been removed by the muffler 309, is released into the atmosphere.

[0058] The carbon dioxide enrichment channel 365 is a channel that guides the carbon dioxide separated by the separation element 400 to the carbon dioxide supply destination 308.

[0059] Next, the detailed configuration of the separation element 400 will be described with reference to Figures 3 and 4. Figure 3 is a schematic diagram showing the general configuration of the separation element 400. Figure 4 is a schematic diagram showing the external configuration of the separation element 400. In Figure 3, the exhaust gas K is represented by a white arrow, and the sweep gas J containing separated carbon dioxide is represented by a diagonal arrow. The movement of carbon dioxide through the separation membrane 422 is represented by a black arrow. Strictly speaking, the exhaust gas K contains oxygen and other elements in addition to carbon dioxide and nitrogen, but for the sake of explanation, only carbon dioxide and nitrogen are shown in Figure 3. Similarly, the sweep gas J contains nitrogen and oxygen and other elements in addition to carbon dioxide, but for the sake of explanation, only carbon dioxide is shown in Figure 3.

[0060] As shown in Figure 4, the separation element 400 is a box-shaped structure. In other words, the separation element 400 has a rectangular shape when viewed in a plan view in the vertical direction. The separation element 400 also has a top plate 401 on the upper end and a bottom plate 402 on the lower end. The separation element 400 draws in and discharges sweep gas J and exhaust gas K from each side surface, which is the surface connecting the top plate 401 and the bottom plate 402. More specifically, the sweep gas J flows in from the right side surface 403 in Figure 4 and flows out from the left side surface 404, which is the surface opposite to the right side surface 403. The exhaust gas K flows in from the front side surface 405 in Figure 4 and flows out from the rear side surface 406, which is the surface opposite to the front side surface 405.

[0061] Furthermore, as shown in Figure 3, the separation element 400 is formed by stacking a first separation membrane 422a, a second separation membrane 422b, a third separation membrane 422c, a fourth separation membrane 422d, and a fifth separation membrane 422e, collectively referred to as separation membrane 422, in the vertical direction at predetermined intervals. On the surface side of the separation membrane 422, there are a first sweep air passage 417a, a second sweep air passage 417b, and a third sweep air passage 417c, collectively referred to as sweep air passage 417. Furthermore, on the back side of the separation membrane 422, there are a first exhaust gas air passage 416a, a second exhaust gas air passage 416b, and a third exhaust gas air passage 416c, collectively referred to as exhaust gas air passage 416. In other words, the separation element 400 is formed by stacking the sweep air passage 417, the separation membrane 422, and the exhaust gas air passage 416. To put it another way, the separation element 400 is formed by stacking separation films 422 at predetermined intervals.

[0062] The separation membrane 422 uses the partial pressure difference of carbon dioxide as a driving force to permeate carbon dioxide from a high-concentration carbon dioxide-containing gas (exhaust gas K in this embodiment) to a low-concentration carbon dioxide-containing gas (sweep gas J in this embodiment). In other words, the carbon dioxide concentration in sweep gas J is lower than that of exhaust gas K. The separation membrane 422 only needs to be able to separate carbon dioxide through the membrane, and various separation membranes such as those using a facilitated transport method or a molecular sieve method can be used as the separation membrane 422. Strictly speaking, various separation membranes do not only allow carbon dioxide to permeate. In other words, various separation membranes are configured so that the amount of carbon dioxide permeated is greater than that of other gas molecules. That is, "separating carbon dioxide" means both separating only carbon dioxide and separating more carbon dioxide than other gas molecules.

[0063] The sweep air passage 417 is an air passage through which carbon dioxide separated by the separation membrane 422 flows. In other words, the sweep air passage 417 is an air passage through which sweep gas J flows. The sweep air passage 417 communicates with the outdoors on its upstream side and takes in atmospheric air as sweep gas J into the sweep air passage 417. The sweep air passage 417 is also connected to the carbon dioxide supply destination 308 on its downstream side via the carbon dioxide enrichment passage 365 (see Figure 2). The vertical height of the sweep air passage 417 is preferably lower than the vertical height of the exhaust gas air passage 416. Furthermore, as shown in Figure 4, the sweep air passage 417 is configured to intersect with the exhaust gas air passage 416.

[0064] The exhaust gas air passage 416 is an air passage through which carbon dioxide flows before being separated by the separation membrane 422. In other words, the exhaust gas air passage 416 is an air passage through which exhaust gas K flows. The exhaust gas air passage 416 is in communication with the third air passage 370c on the upstream side, and takes exhaust gas C into the exhaust gas air passage 416 as exhaust gas K (see Figure 2). The exhaust gas air passage 416 is also in communication with the fourth air passage 370d on the downstream side, and supplies exhaust gas D, which has a lower carbon dioxide concentration than exhaust gas C, to the muffler 309.

[0065] The above is a description of the configuration of the air conditioning system 1.

[0066] Next, the operation of the air conditioning system 1 will be explained. Specifically, the cooling operation, heating operation, and carbon dioxide separation process will be described. (Air conditioning operation) First, let's explain the cooling operation with reference to Figure 1. Cooling operation is an operating mode designed to lower the temperature of the space being air-conditioned.

[0067] The compressor 101, which compresses the refrigerant, is driven by a gas engine 102. The high-temperature, high-pressure refrigerant compressed by the compressor 101 flows into the oil separator 103. The highly purified gaseous refrigerant, from which the oil has been separated in the oil separator 103, passes through the four-way valve 110 and dissipates heat by exchanging heat with the outside air in the outdoor heat exchanger 105, where it condenses. The refrigerant that has passed through the outdoor heat exchanger 105 (high-pressure liquid refrigerant) is then supplied to the indoor unit 200. The high-pressure liquid refrigerant that has flowed into the indoor unit 200 is depressurized by the depressurization device 203, becoming a gas-liquid two-phase state, and flows into the indoor heat exchanger 201. The gas-liquid two-phase refrigerant in the indoor heat exchanger 201 absorbs heat and evaporates by exchanging heat with the air in the space to be air-conditioned, becoming a low-pressure gaseous refrigerant and flowing out of the indoor unit 200. In other words, the refrigerant lowers the temperature of the air-conditioned space by removing heat from the air in that space. The low-pressure gaseous refrigerant that flows out of the indoor unit 200 flows back into the outdoor unit 100. The gaseous refrigerant that flows into the outdoor unit 100 passes through the four-way valve 110 and the accumulator 109 and returns to the compressor 101, repeating the above process. The oil separated by the oil separator 103 flows into the suction piping of the compressor 101 through an oil return pipe (not shown) and returns to the compressor 101, repeating the above process.

[0068] The above is an explanation of the cooling operation of air conditioning unit 1. (Heating operation) Next, we will explain heating operation with reference to Figure 1. Heating operation is an operating mode for raising the temperature of the space that is to be air-conditioned.

[0069] The compressor 101, which compresses the refrigerant, is driven by a gas engine 102. The high-temperature, high-pressure refrigerant compressed by the compressor 101 flows into the oil separator 103. The highly purified gaseous refrigerant, from which the oil has been separated in the oil separator 103, passes through the four-way valve 110 and is supplied to the indoor unit 200 (see the black dashed arrow in Figure 1). The high-pressure gaseous refrigerant that has flowed into the indoor unit 200 flows into the indoor heat exchanger 201 and exchanges heat with the air in the space to be air-conditioned. It then releases heat and condenses. In other words, the refrigerant raises the temperature of the air-conditioned space by transferring heat to the air in the space being air-conditioned. It then flows out of the indoor unit 200 as high-pressure liquid refrigerant. The high-pressure liquid refrigerant that has flowed out of the indoor unit 200 flows back into the outdoor unit 100. The liquid refrigerant is depressurized by the depressurization device 107 and flows into the outdoor heat exchanger 105 as a gas-liquid two-phase state. The gas-liquid two-phase refrigerant that has flowed into the outdoor heat exchanger 105 exchanges heat with the outside air, absorbs heat, and then evaporates, becoming a low-pressure gaseous refrigerant. The low-pressure gaseous refrigerant passes through the four-way valve 110 (dashed arrow in Figure 1) and the accumulator 109 and returns to the compressor 101, where the above process is repeated. The oil separated by the oil separator 103 flows into the suction piping of the compressor 101 through an oil return pipe (not shown), returns to the compressor 101, and the above process is repeated.

[0070] The above is a description of the heating operation of air conditioning unit 1. (Carbon dioxide separation treatment) Next, the carbon dioxide separation process will be explained with reference to Figure 2.

[0071] The carbon dioxide separation process is a process in which carbon dioxide is separated from the exhaust gas produced by the gas engine 102 using the carbon dioxide separation system 300. Furthermore, the carbon dioxide separation process is performed regardless of the operating mode of the air conditioning unit 1 (cooling operation or heating operation). In the following explanation, the flow of the exhaust gas will be described first, followed by a description of the control contents of the control unit 70.

[0072] The exhaust gas A1 generated by the gas engine 102 flows into the first passage 370a. At branching point P, the exhaust gas A1 that has flowed into the first passage 370a branches into exhaust gas S that goes to the first bypass passage 360a and exhaust gas A2 that goes to the cooling section 303.

[0073] The exhaust gas A2 that flows into the cooling section 303 exchanges heat with the cooling water supplied from the cooling water supply section 330, becoming exhaust gas B, which is colder than exhaust gas A2, and flows into the second flow path 370b. More precisely, the temperature of exhaust gas A2 drops below the dew point temperature, and the moisture contained in exhaust gas A2 condenses, causing a decrease in absolute humidity. In other words, exhaust gas B becomes colder and has lower humidity (absolute humidity) than exhaust gas A2.

[0074] Next, exhaust gas B flows into the heating section 307 via the second flow path 370b. The exhaust gas B that flows into the heating section 307 exchanges heat with the exhaust gas S that flows into the heating section 307 from the first bypass flow path 360a without mixing, resulting in exhaust gas C, whose temperature has risen above that of exhaust gas B, flowing out into the third flow path 370c. More precisely, the temperature of exhaust gas C is below the service life temperature Tlim of the separation element 400 (60°C in this embodiment). In other words, as exhaust gas B flows into the heating section 307, its temperature rises, and its relative humidity decreases accordingly. That is, exhaust gas C has a higher temperature and lower relative humidity than exhaust gas B.

[0075] Next, exhaust gas C, whose relative humidity is lower than that of exhaust gas B, flows into the separation element 400 via the third flow path 370c. The exhaust gas C that flows into the separation element 400 has its carbon dioxide separated, resulting in exhaust gas D with a reduced carbon dioxide concentration. The carbon dioxide separated by the separation element 400 is then guided to the carbon dioxide supply destination 308 via the carbon dioxide enrichment flow path 365.

[0076] Next, the exhaust gas D that flows out from the separation element 400 flows into the muffler 309 via the fourth passage 370d. Inside the muffler 309, the exhaust gas D has harmful substances such as carbon monoxide or nitride oxides removed, and is then released outdoors as exhaust gas E with a reduced concentration of harmful substances.

[0077] Next, we will explain the control contents of the control unit 70 in the carbon dioxide separation process.

[0078] The control unit 70 controls the carbon dioxide separation system 300 to lower the exhaust gas temperature so that it is below the operating temperature Tlim of the separation element 400, and then to slightly raise the exhaust gas temperature. This suppresses condensation on the separation element 400, and thus suppresses a decrease in the separation efficiency of the separation element 400. For the sake of explanation, the control contents of the control unit 70 will be described below in three parts: dehumidification, cooling, and heating.

[0079] First, the dehumidification process will be explained with reference to Figures 2 and 5. Figure 5 is a flowchart showing the flow of the dehumidification process.

[0080] The control unit 70 acquires the absolute humidity AH1 of exhaust gas A2 measured by the first humidity measuring unit 325 (S101). The control unit 70 also acquires the absolute humidity AH2 of exhaust gas B measured by the second humidity measuring unit 324 (S103). Furthermore, the control unit 70 calculates the dehumidification rate (amount of dehumidification) by the cooling unit 303 based on the acquired absolute humidity AH1 and absolute humidity AH2 (S105). Specifically, in this embodiment, it is calculated as (AH2 - AH1) / AH1 = 0.2. In other words, in this embodiment, the amount of moisture contained in exhaust gas A2 is reduced by 20% after passing through the cooling unit 303. The method for calculating the amount of dehumidification is not particularly limited. For example, the dehumidification rate (amount of dehumidification) may be calculated by subtracting the absolute humidity AH1 from the absolute humidity AH2.

[0081] Next, the control unit 70 determines whether the calculated dehumidification rate is less than or equal to a predetermined rate (S107). More specifically, if the dehumidification rate is less than or equal to a predetermined rate (if the answer to S107 is YES), the control unit 70 increases the amount of cooling water supplied from the cooling water supply unit 330 to the cooling unit 303 (S109). Specifically, for example, if the predetermined rate is "30%", and the dehumidification rate by the cooling unit 303 is "20%", the control unit 70 increases the amount of cooling water supplied to the cooling unit 303. In other words, the control unit 70 increases the amount of cooling water supplied when the amount of dehumidification is insufficient. The predetermined rate can be appropriately determined by taking into account the cooling capacity of the cooling water supply unit 330 or the amount of moisture in the exhaust gas A1 generated by the gas engine 102. After that, the process returns to step S101 and the same process is repeated thereafter. Furthermore, if the amount of dehumidification in step S107 is greater than a predetermined percentage (in the case of NO in S107), the process returns to step S101 and the same process is repeated thereafter.

[0082] This configuration allows for a more reliable reduction in the amount of moisture contained in the exhaust gas, thereby suppressing condensation in the separation element 400. As a result, a decrease in the carbon dioxide separation efficiency of the separation element 400 can be suppressed.

[0083] Next, the cooling process will be explained with reference to Figures 2, 6, and 8. Figure 6 is a flowchart showing the flow of the cooling process. Figure 8 is a schematic diagram showing the temperature change of the exhaust gas.

[0084] As shown in Figure 6, the control unit 70 acquires the temperature Tb of exhaust gas B measured by the second temperature measuring unit 323 (S201). Here, the temperature Tb of exhaust gas B is set to "50°C".

[0085] Next, the control unit 70 determines whether the temperature Tb of the exhaust gas B is below a predetermined temperature T2 (S203). If the temperature Tb is below the predetermined temperature T2 (if S203 is YES), the process returns to step S201 and repeats thereafter. On the other hand, if the temperature Tb is above the predetermined temperature T2 (if S203 is NO), the control unit 70 increases the amount of cooling water supplied from the cooling water supply unit 330 to the cooling unit 303. After that, the process returns to step S201 and repeats thereafter. The same process is repeated. In this embodiment, the predetermined temperature T2 is set to "52°C".

[0086] The predetermined temperature T2 is a temperature below the service life temperature Tlim of the separation element 400 (60°C in this embodiment), as shown in Figure 8. More precisely, it is preferable that the predetermined temperature T2 is 5°C or more lower than the service life temperature Tlim. In this embodiment, the predetermined temperature T2 is set 8°C lower than the service life temperature Tlim. This is to prevent the exhaust gas temperature from exceeding the service life temperature Tlim when the heating unit 307 raises the temperature downstream of the cooling unit 303.

[0087] This configuration allows for a more reliable reduction in exhaust gas temperature, thereby reducing the risk of damage to the separation element 400 caused by use at high temperatures.

[0088] Next, the heating process will be described with reference to Figures 2, 7, and 8. Figure 7 is a flowchart showing the flow of the heating process. The control unit 70 determines whether the temperature Tc measured by the third temperature measuring unit 321 is within a predetermined range defined by the maximum threshold and the minimum threshold, and adjusts the flow rate of exhaust gas A2 flowing into the bypass channel 360a based on the determination result.

[0089] As shown in Figures 7 and 2, the control unit 70 acquires the temperature Tc of the exhaust gas C measured by the third temperature measuring unit 321 (S301). Here, the temperature Tc of the exhaust gas C is set to "56°C".

[0090] Next, the control unit 70 determines whether the temperature Tc of the exhaust gas C is less than or equal to the minimum threshold Tmin (S303). If the temperature Tc is less than or equal to the minimum threshold Tmin (if S303 is YES), the control unit 70 controls the flow rate control means 350 to increase the flow rate of exhaust gas A2 flowing into the bypass flow path 360a (S307). On the other hand, if the temperature Tc is greater than the minimum threshold Tmin (if S303 is NO), the control unit 70 determines whether the temperature Tc is greater than or equal to the maximum threshold Tmax (S305). If the temperature Tc is greater than or equal to the maximum threshold Tmax (if S305 is YES), the control unit 70 controls the flow rate control means 350 to decrease the flow rate of exhaust gas A2 flowing into the bypass flow path 360a (S309). On the other hand, if the temperature Tc is less than the maximum threshold Tmax (if S305 is NO), the process returns to step S301 and the same process is repeated thereafter.

[0091] As shown in Figure 8, in this embodiment, the minimum threshold Tmin is set to "55°C" and the maximum threshold Tmax is set to "58°C". The maximum threshold Tmax and minimum threshold Tmin may be determined appropriately, taking into consideration the cooling capacity of the cooling water supply unit 330 or the temperature of the exhaust gas generated from the gas engine.

[0092] This configuration makes it possible to reduce the relative humidity of the exhaust gas C flowing into the separation element 400. In other words, it is possible to suppress the decrease in separation efficiency caused by condensation occurring inside the separation element 400. Furthermore, since the temperature of the exhaust gas C can be kept below the operating temperature Tlim of the separation element 400, the risk of damage to the separation element 400 can also be reduced. (modified version) The present invention has been described above based on embodiments. These embodiments are illustrative, and it will be understood by those skilled in the art that various modifications are possible for each component or combination of processes, and that such modifications also fall within the scope of the present invention. Modifications in this embodiment will now be described. In the following description, Figure 9 may be referred to. Figure 9 is a schematic diagram showing the exhaust gas flow path in a modification. For convenience of explanation, the flow rate control means 350 is not shown in Figure 9.

[0093] In Embodiment 1, as shown in Figure 2, at the branching point P of the first flow path 370a, exhaust gas The example shown involves gas S flowing out towards the first bypass channel 360a and exhaust gas R flowing in from the second bypass channel 360b, but this is not the only example.

[0094] For example, as shown in Figure 9, the intersection point of the first flow path 370a and the first bypass flow path 360a, and the intersection point of the first flow path 370a and the second bypass flow path 360b may be located at different positions. More specifically, if the intersection point of the central axis X3 of the first flow path 370a and the central axis X1 of the first bypass flow path 360a is defined as intersection point M, and the intersection point of the central axis X3 and the central axis X2 of the second bypass flow path 360b is defined as intersection point N, then intersection point M is located upstream of intersection point N. In other words, intersection point M is located closer to the gas engine 102 than intersection point N.

[0095] This configuration makes it possible to suppress the flow of exhaust gas R, which merges from the second bypass passage 360b into the first passage 370a, into the first bypass passage 360a. In other words, it is possible to suppress the flow of exhaust gas R, whose temperature has decreased by passing through the heating section 307, back into the first bypass passage 360a. As a result, the temperature drop of exhaust gas S sent to the heating section 307 can be suppressed, and the heat exchange efficiency in the heating section 307 can be maintained or improved.

[0096] Furthermore, while Embodiment 1 shows an example where the first bypass channel 360a and the second bypass channel 360b are approximately perpendicular to the first channel 370a, the embodiment is not limited to this.

[0097] For example, as shown in Figure 9, the angle θ1 formed by the central axis X1 of the first bypass channel 360a and the central axis X3 of the first bypass channel 370a may be set to be an acute angle. In other words, angle θ1 is the angle formed by the central axis X3 and the central axis X1 on the left side of the central axis X3 (the side of the first bypass channel 360a) and downstream of the intersection point M. To put it another way, the distance W between the first channel 370a and the first bypass channel 360a increases as you move downstream. That is, when comparing distance W1 with distance W2 downstream of distance W1, distance W1 is narrower than distance W2.

[0098] This configuration makes it easier for exhaust gas A1 to flow into the first bypass passage 360a. In other words, it becomes possible to more reliably reduce the relative humidity of the exhaust gas in the heating section 307, and as a result, it is possible to suppress the decrease in separation efficiency due to condensation.

[0099] Similarly, the angle θ2 formed by the central axis X2 of the second bypass channel 360b and the central axis X3 of the first channel 370a may be set to be acute. In other words, angle θ2 is the angle formed by the central axis X3 and the central axis X2 on the right side of the central axis X3 (the side of the second bypass channel 360b) and upstream of the intersection point N. To put it another way, the distance W between the first channel 370a and the second bypass channel 360b increases as you move upstream. That is, when comparing the distance W3 with the distance W4 upstream of distance W3, distance W3 is narrower than distance W4.

[0100] This configuration makes it easier for exhaust gas R to flow downstream (towards the cooling section 303) when it enters the first flow path 370a. In other words, exhaust gas R, which is at a lower temperature than exhaust gas S and exhaust gas A1, is more likely to flow into the cooling section 303 without entering the first bypass flow path 360a. As a result, the temperature of exhaust gas A2 (mixed with exhaust gas R) entering the cooling section 303 decreases, narrowing the required temperature reduction in the cooling section 303, and making it possible to more reliably reduce the temperature of exhaust gas A2 to the target temperature (T2). That is, the risk of thermal damage to the separation element 400 can be further reduced.

[0101] Furthermore, in Embodiment 1, as shown in Figure 2, a muffler 309 is provided downstream of the separation element 400, but the invention is not limited to this configuration.

[0102] The separation element 400 may be provided downstream of the muffler 309.

[0103] With this configuration, when the muffler 309 has a catalyst and generates carbon dioxide by oxidizing carbon monoxide, the concentration of carbon dioxide in the exhaust gas flowing into the separation element 400 can be increased. In other words, the carbon dioxide separation efficiency in the separation element 400 can be improved.

[0104] Furthermore, in Embodiment 1, as shown in Figure 5, only whether the dehumidification rate is below a predetermined rate was determined, but this is not the only limitation.

[0105] For example, the control unit 70 may be configured to determine whether the dehumidification rate is within a predetermined range defined by a maximum and minimum value, and to control the cooling water supply unit 330 based on the result. More specifically, the configuration may be such that if the dehumidification rate exceeds the maximum value, the amount of cooling water supplied is reduced, and if the dehumidification rate falls below the minimum value, the amount of cooling water supplied is increased.

[0106] This configuration allows the output of the cooling water pump to be kept within an optimal range, thus suppressing unnecessary energy consumption.

[0107] Furthermore, while Embodiment 1 shows an example where only whether the temperature Tb is less than or equal to a predetermined temperature T2 is determined, as shown in Figure 6, the embodiment is not limited to this.

[0108] For example, the control unit 70 may be configured to determine whether the temperature Tb is within a predetermined range defined by a maximum and minimum value, and to control the flow rate of the exhaust gas S circulating through the bypass passage 360 ​​based on the result. More specifically, if the temperature Tb exceeds the maximum value, the amount of cooling water supplied may be increased, and if it falls below the minimum value, the amount of cooling water supplied may be decreased.

[0109] Furthermore, in Embodiment 1, as shown in Figure 7, the amount of exhaust gas S flowing through the bypass passage 360 ​​is adjusted based on the temperature Tc of the exhaust gas C, but the invention is not limited to this.

[0110] For example, the control unit 70 may be configured to determine whether the relative humidity RH3 measured by the third humidity measuring unit 322 is below a predetermined threshold, and to control the flow rate of the exhaust gas S circulating in the bypass flow path 360 based on the result. More specifically, the control unit 70 may be configured to maintain the flow rate of the exhaust gas S circulating in the bypass flow path 360 if the relative humidity RH3 is below a predetermined value, and to increase the flow rate of the exhaust gas S circulating in the bypass flow path 360 if it is not below a predetermined threshold, i.e., if the relative humidity is too high.

[0111] This configuration allows for direct control based on relative humidity, thus more reliably suppressing condensation in the separation element 400. As a result, the decrease in carbon dioxide separation efficiency can be suppressed. [Explanation of Symbols]

[0112] 1. Air conditioning system 2 Refrigerant piping 70 Control Unit 100 Outdoor Units 101 Compressor 102 Gas Engine 103 Oil Separator 104 Outdoor fan 105 Outdoor heat exchanger 107 Pressure Reducing Device 109 Accumulator 110 Four-way valve 200 Indoor Units 201 Indoor heat exchanger 202 Indoor Fan 203 Pressure Reducing Device 300 Carbon Dioxide Separation System 350 Flow rate control means 303 Temperature cooling section 307 Heating section 309 Muffler 320 First temperature measurement section 321 Third temperature measurement section 322 Third humidity measurement section 323 Second temperature measurement section 324 Second humidity measuring section 325 First humidity measuring section 330 Cooling water supply section 333 Cooling water pump 335 Reservoir Tank 365 Carbon Dioxide Enrichment Channels 370a First channel 370b Second flow path 370c Third flow path 370d Fourth flow path 370e Fifth flow path 400 separation elements 401 Tabletop 402 Bottom plate 403 Right side 404 Left side 405 Front and side view 406 Posterior side 416a First exhaust gas air passage 416b Second exhaust gas air passage 416c Third exhaust gas air duct 417 Sweep Airflow 417a First sweep airflow path 417b Second sweep airway 417c Third sweep airway 422 Separation membrane 422a First separation membrane 422b Second separation membrane 422c Third separation membrane 422d Fourth separation membrane 422e Fifth separation membrane

Claims

1. A cooling unit for reducing the temperature of exhaust gases produced from an internal combustion engine, A heating unit is provided downstream of the cooling unit to raise the temperature of the exhaust gas, A separation element is provided downstream of the heating section for separating carbon dioxide from the exhaust gas, Equipped with, The heating section suppresses condensation in the separation element by reducing the relative humidity of the exhaust gas. Carbon dioxide separation system.

2. The carbon dioxide separation system according to claim 1, wherein the heating unit raises the temperature of the exhaust gas in a temperature range such that the temperature of the exhaust gas downstream of the heating unit is below the service temperature of the separation element.

3. A bypass passage connecting the internal combustion engine and the heating section without going through the cooling section, The heating section exchanges heat between the exhaust gas that has flowed through the cooling section and the exhaust gas that has flowed through the bypass passage, A flow rate control means for controlling the flow rate of the exhaust gas flowing through the bypass passage, A temperature measuring unit that measures the temperature downstream of the heating unit, The system includes a control unit that controls the flow rate of the exhaust gas flowing through the bypass channel by controlling the flow rate control means, The control unit, Based on the temperature measured by the temperature measuring unit, the flow rate control means is controlled. The carbon dioxide separation system according to claim 1.

4. The control unit, The temperature measurement unit determines whether the temperature measured is within a predetermined range defined by the maximum threshold and the minimum threshold. If the temperature measured by the temperature measuring unit is greater than the maximum threshold, the flow rate control means is controlled to reduce the flow rate of the exhaust gas flowing through the bypass passage. If the temperature measured by the temperature measuring unit is less than the minimum threshold, the flow rate control means is controlled to increase the flow rate of the exhaust gas flowing through the bypass passage. The carbon dioxide separation system according to claim 3.

5. The carbon dioxide separation system according to claim 1, wherein the separation element is formed by stacking separation membranes at predetermined intervals.

6. An air conditioning system comprising the carbon dioxide separation system according to claim 1 or 2.

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