Multi-control system of carbon dioxide capture complex process and multi-controlling method thereof

Abstract

The present invention relates to a multi-control system for a combined carbon dioxide capture process and a multi-control method thereof. More specifically, the multi-control system for a combined carbon dioxide capture process comprises: a gas purification unit for removing impurities, including moisture, contained in an incoming flue gas; a primary cooling unit having a cooling cycle arranged in two stages, configured to flow through a compressor and a heat exchanger to cool the gas that has passed through the gas purification unit; a separation unit for separating CO2 gas from the gas cooled in the primary cooling unit; a secondary cooling unit having a cooling cycle arranged in three stages, configured to flow through a compressor and a heat exchanger to cool the CO2 gas separated through the separation unit; a distillation tower for producing liquefied CO2 from which impurities have been removed by distilling and separating the CO2 gas cooled in the secondary cooling unit to increase CO2 purity; an analysis unit for calculating the purity and capture rate of CO2 using an analyzer with the final product obtained from the distillation tower; a storage tank for storing the liquefied CO2 separated from the distillation tower; and the gas purification unit, the primary cooling unit, the separation unit, the It is configured to include a control unit that controls the operation, pressure, temperature, and flow rate of one or more of the secondary cooling unit, the distillation tower, and the storage tank, thereby enabling stable and efficient capture of carbon dioxide with a high concentration through low-temperature cooling.

Description

Technology Field

[0001] The present invention relates to a carbon dioxide capture process and aims to provide a multi-control system and a multi-control method for a composite carbon dioxide capture process capable of stably and efficiently capturing carbon dioxide at high concentrations using a low-temperature cooling carbon dioxide (CO2) capture process. Background Technology

[0002] There are various methods of carbon dioxide (CO2) capture technology, including wet capture, dry capture, membrane capture, and cryogenic capture. Cryogenic capture is a process that captures and liquefies CO2 contained in coal-fired power plants, LNG combined cycle power plants, and other industrial flue gases using the cold energy from LNG vaporization. LNG vaporization cold energy (-162℃) refers to the ultra-low temperature energy possessed by NG (liquefied natural gas), which is the cold energy wasted at LNG receiving terminals by using vaporizers such as seawater vaporizers and combustion vaporizers.

[0003] The advantage of the deep cryogenic capture and liquefaction process using the cold energy from LNG vaporization is that, excluding moisture (H2O) among the major components of flue gas, CO2 has the highest liquefaction and sublimation temperatures, allowing for the selective separation of only CO2 when the flue gas is cooled. Additionally, deep cryogenic capture of CO2 using LNG cold energy does not require renewable energy, unlike wet CO2 capture processes. Finally, in conventional CO2 capture processes, compressed liquefaction is performed again to transport the separated CO2 after gas separation; however, this process consumes a large amount of electricity using a compressor. In contrast, the deep cryogenic CO2 capture process separates CO2 directly into a liquid state, eliminating the need for a separate compressed liquefaction process and thus reducing equipment and operating costs.

[0004] In the deep cryogenic CO2 capture technology for coal-fired power plant flue gas utilizing LNG cold energy, regarding the form of the final product, other technologies utilize LNG cold energy (-162℃) to cool coal-fired power plant flue gas (53℃) at atmospheric pressure to -80℃ to capture CO2 contained in the flue gas through a phase change (gas → solid), which requires freezing capture via dry ice formation and then liquefying for transportation; however, this technology utilizes membrane separation technology and a distillation tower to capture and utilize high-concentration liquid CO2 from the flue gas.

[0005] As shown in Fig. 1, the conventional technology is a technology that utilizes a cooling cycle involving compressor-heat exchanger cooling-expansion-liquefaction, which cools the flue gas through heat exchange using waste cold energy from LNG power generation, and captures carbon dioxide (CO2) at a high concentration using a gas separation membrane and a distillation tower, and increases efficiency.

[0006] However, these conventional cryogenic technologies cause problems such as pipe blockages or damage to pipes and valves due to freezing during the liquefaction process. Fluids like CO2 liquefy more easily as the temperature decreases and the pressure increases. Higher temperatures require correspondingly higher pressure, whereas lowering the temperature allows liquefaction at lower pressures. Various problems can arise due to the temperature and pressure differences resulting from these fluid changes. As the flow rate increases, the temperature decreases significantly; consequently, freezing occurs within pipes and valves, causing frost to form on the surfaces when the pipe temperature drops below 0°C.

[0007] In the CO2 capture and liquefaction process, the CO2 is stored in vacuum-insulated tanks or containers after passing through a low-temperature cooling process. However, even with vacuum insulation, 100% insulation is impossible because heat is directly transferred through fittings and piping. For this reason, it is difficult to maintain pressure and temperature. Consequently, the safety of each pipe and valve is compromised, and the introduction of controls to maintain temperature and pressure becomes unavoidable.

[0008] If a liquefied carbon dioxide tank is overcharged, overpressure forms inside the tank, requiring control to prevent this. Furthermore, if control is not maintained, severe pressure fluctuations in the regulator may occur. Additionally, the critical temperature of carbon dioxide is 31.35°C; if the temperature of the liquefied carbon dioxide container exceeds this critical point, the pressure rises rapidly and becomes difficult to control. In this case, as the temperature rises, the liquid phase vaporizes and the pressure increases, affecting the process; therefore, process control is required to ensure operation throughout all four seasons. Prior art literature

[0009] Korean Registered Patent No. 10-1906917 The problem to be solved

[0010] Considering the aforementioned problems, the present invention aims to provide a multi-control system and a multi-control method for a carbon dioxide (CO2) capture complex process having a high concentration of carbon dioxide, through the introduction of safety devices and automatic control, in order to solve long-term operational losses and safety issues of the carbon dioxide (CO2) capture process through low-temperature cooling. means of solving the problem

[0011] The multi-control system of the carbon dioxide capture complex process of the present invention comprises: a gas purification unit for removing impurities, including moisture, contained in the incoming flue gas; a primary cooling unit having a cooling cycle arranged in two stages, configured to flow through a compressor and a heat exchanger to cool the gas that has passed through the gas purification unit; a separation unit for separating CO2 gas from the gas cooled in the primary cooling unit; a secondary cooling unit having a cooling cycle arranged in three stages, configured to flow through a compressor and a heat exchanger to cool the CO2 gas separated through the separation unit; a distillation tower for producing liquefied CO2 from which impurities have been removed by distilling and separating the CO2 gas cooled in the secondary cooling unit to increase CO2 purity; an analysis unit for calculating the purity and capture rate of CO2 using an analyzer from the final product obtained from the distillation tower; a storage tank for storing the liquefied CO2 separated from the distillation tower; and operation, pressure, of any one or more of the gas purification unit, the primary cooling unit, the separation unit, the secondary cooling unit, the distillation tower, and the storage tank. It is characterized by including a control unit that controls temperature and flow rate.

[0012] In the multi-control system of the carbon dioxide capture composite process of the present invention, the gas purification unit may include a gas purification filter that removes particulate impurities, such as dust contained in the incoming flue gas, and a gas-water separator that removes condensate by condensing moisture (H2O) contained in the exhaust gas after passing through the gas purification filter.

[0013] In the multi-control system of the carbon dioxide capture composite process of the present invention, the primary cooling unit may be configured with a two-stage cooling cycle consisting of a first cooling cycle configured to flow the gas through a first compressor and a first heat exchanger, and a second cooling cycle configured to flow the gas from the first cooling cycle through a second compressor and a second heat exchanger.

[0014] In the multi-control system of the carbon dioxide capture composite process of the present invention, the separation unit can separate CO2 gas by passing the gas cooled in the primary cooling unit through a separation membrane.

[0015] In order to improve the carbon dioxide capture rate in the above separation section, the residual gas after passing through the separation membrane can be recirculated back to the above primary cooling section.

[0016] In the multi-control system of the carbon dioxide capture composite process of the present invention, the secondary cooling unit may be configured with a three-stage cooling cycle consisting of a third cooling cycle configured to flow the CO2 gas through a third compressor and a third heat exchanger, a fourth cooling cycle configured to flow the gas from the third cooling cycle through a fourth compressor and a fourth heat exchanger, and a fifth cooling cycle configured to flow the gas from the fourth cooling cycle through a fifth compressor and a fifth heat exchanger.

[0017] In the multi-control system of the carbon dioxide capture complex process of the present invention, the distillation tower may be selected from either a multi-stage tower or a packed tower, and preferably, a packed tower may be used.

[0018] To improve the carbon dioxide capture rate in the distillation column, the residual gas after passing through the distillation column can be recirculated back to the separation unit.

[0019] In the multi-control system of the carbon dioxide capture complex process of the present invention, the analysis unit identifies and analyzes the results of the carbon dioxide capture performance evaluation through the evaluation of inputs and products, and calculates the purity and capture rate of carbon dioxide (CO2), which is the final product, from the gas captured through the carbon dioxide capture performance evaluation using an analyzer.

[0020] In the multi-control system of the carbon dioxide capture complex process of the present invention, the storage tank may be a movable, mobile storage tank.

[0021] The above storage tank may be equipped with a level control valve to prevent the formation of overpressure inside the storage tank when liquefied CO2 is overfilled into the storage tank, and an interlock to block the inflow of liquefied CO2 into the storage tank.

[0022] The above storage tank may be equipped with a relief valve to prevent pressure from rising.

[0023] In the multi-control system of the carbon dioxide capture composite process of the present invention, the control unit receives pressure, temperature, and flow rate detected by sensors installed in one or more of the gas purification unit, the primary cooling unit, the separation unit, the secondary cooling unit, the distillation tower, and the storage tank, determines whether a preset reference value is reached, and outputs a control signal according to the determination result to control the pressure, temperature, and flow rate to a predetermined level.

[0024] In the above control unit, pressure, temperature, and flow rate can be controlled by manual control and automatic control.

[0025] To achieve another objective, the multi-control method of the carbon dioxide capture composite process of the present invention may include: a purification step of purifying flue gas in a gas purification unit; a first cooling step of cooling flue gas through a first cooling unit; a first judgment step of determining whether the temperature and pressure of the gas cooled in the first cooling step satisfy a preset standard range; a separation membrane step of separating CO2 gas through a separation membrane by injecting the gas into a separation unit if the temperature and pressure of the gas cooled in the first judgment step satisfy the standard range and are suitable; a second cooling step of cooling the CO2 gas from the separation membrane step through a second cooling unit; a second judgment step of determining whether the temperature and pressure of the gas cooled in the second cooling step satisfy a preset standard range; a distillation tower step of producing CO2 in a liquid state with impurities removed by injecting the gas into a distillation tower and distilling and separating it if the temperature and pressure of the gas cooled in the second judgment step satisfy the standard range; and a storage step of storing the CO2 in a liquid state separated from the distillation tower through the distillation tower step in a storage tank.

[0026] If the temperature and pressure of the cooled gas in the first judgment step above do not fall within the standard range, the gas can be supplied back to the first cooling unit to perform the first cooling step again.

[0027] If the temperature and pressure of the cooled gas in the second judgment step above do not fall within the standard range, the gas can be supplied back to the second cooling unit to perform the second cooling step again.

[0028] In the above membrane step, the residual gas that has passed through the membrane can be supplied back to the primary cooling unit to perform the primary cooling step again.

[0029] In the above distillation column stage, the residual gas after passing through the distillation column is supplied back to the separation section to sequentially repeat the membrane stage, secondary cooling stage, and distillation column stage.

[0030] If the liquefied carbon dioxide (CO2) gas from the above distillation tower stage has a CO2 purity of 99.9% or higher and a CO2 capture rate of 95% or higher, the residual gas from the distillation tower can be stopped without further circulation. Effects of the invention

[0031] The multi-control system of the carbon dioxide capture composite process of the present invention has the effect of maintaining optimal operating conditions by minimizing temperature and pressure fluctuations of carbon dioxide (CO2) during the carbon dioxide capture process and enhancing process stability. In addition, by controlling the temperature, pressure, and supply flow rate of the captured liquid carbon dioxide (CO2), it is possible to increase carbon dioxide production capacity compared to conventional deep cryogenic CO2 capture processes.

[0032] The multi-control system of the carbon dioxide capture composite process of the present invention has a double-insulated structure for the piping and valves connecting each equipment device constituting the system for protecting equipment from low-temperature cooling, and additionally, by installing a heater, the system can be operated stably even in freezing conditions.

[0033] A single control panel is constructed as the control unit to monitor the entire process by identifying the temperature, pressure, and flow rate of each piece of equipment constituting the multi-control system of the carbon dioxide capture composite process of the present invention through sensors, thereby facilitating the performance evaluation of the equipment. Furthermore, since users can conveniently detect process anomalies and operate the process more efficiently, maintainability is improved, resulting in reduced operating costs and enhanced long-term operational stability of the process. Brief explanation of the drawing

[0034] Figure 1 is a schematic diagram of a conventional low-temperature cooling carbon dioxide capture system. Figure 2 is a schematic diagram of a multi-control system for the carbon dioxide capture composite process of the present invention. FIG. 3 is a flowchart of a multi-control method for a carbon dioxide capture composite process according to one embodiment of the present invention. FIG. 4 is a flowchart illustrating a method for controlling the circulation of residual gas in a multi-control method of a carbon dioxide capture composite process according to one embodiment of the present invention. Specific details for implementing the invention

[0035] The multi-control system and multi-control method of the carbon dioxide capture composite process of the present invention will be described below with reference to the illustrated drawings. However, this is merely a reference for explaining the present invention in detail, and the present invention is not limited thereto and can be implemented in various forms.

[0036] Terms such as “composed,” “comprising,” or “added” as used in this specification should not be interpreted as necessarily including all of the various components described in the specification, and should be interpreted as some of the components may not be included and additional components may be included.

[0037] Terms including ordinal numbers, such as first, second, first, second, etc., may be used to describe various components, but said components are not limited by said terms. These terms are used solely for the purpose of distinguishing one component from another.

[0038] Figure 2 is a schematic diagram of a multi-control system for the carbon dioxide capture composite process of the present invention.

[0039] As shown in FIG. 2, the multi-control system of the carbon dioxide capture composite process of the present invention includes a gas purification unit (102), a primary cooling unit (103), a separation unit (104), a secondary cooling unit (105), a distillation tower (106), an analysis unit (107), a storage tank (108), and a control unit (109).

[0040] In the multi-control system of the carbon dioxide capture complex process, the gas purification unit (102) performs a purification process to obtain high-purity carbon dioxide by removing moisture (H2O) and fine dust, etc. from the injected flue gas (101).

[0041] Exhaust gas (101) of about 50°C introduced into the gas purification unit (102) passes through a purification filter (21) to remove particulate impurities such as fine dust from the exhaust gas (101). After the purification filter (21), to remove moisture (H2O), the moisture (H2O) contained in the exhaust gas introduced through the gas-water separator (22) is condensed and removed as condensate.

[0042] If the gas purification unit (102) is not passed through, a small amount of moisture may cause mechanical defects in subsequent equipment devices such as compressors or meters.

[0043] The first cooling unit (103) is configured with a cooling cycle configured to flow through a compressor and a heat exchanger to cool the gas that has passed through the gas purification unit (102), and consists of a compression-cooling-expansion cycle. Since liquefaction cannot be achieved by lowering the temperature alone, according to the thermodynamic behavior of the Mollier diagram (PH diagram), the gas is pressurized and heated to a specific temperature, and after intermediate cooling while maintaining the pressure, the temperature drops rapidly when the pressure is lowered. Based on this theory, the first cooling unit (103) is configured with a two-stage cooling cycle consisting of a first cooling cycle configured to flow the gas through a first compressor (31) and a first heat exchanger (41), and a second cooling cycle configured to flow the gas from the first cooling cycle through a second compressor (32) and a second heat exchanger (42).

[0044] In the primary cooling section (103), the cooling cycle can be configured with two or more stages as needed. When pressurizing the fluid, using multiple compressors increases equipment costs, but reduces the operating costs of the cooling cycle compared to using a single compressor. Therefore, the optimal cooling cycle stage can be determined through process simulation according to each process.

[0045] After passing through a two-stage cooling cycle in the first cooling section (103), the gas is obtained with a pressure of 3 bar and a temperature of 5 ℃, and a carbon dioxide (CO2) content of 15.1%, and other components including moisture (H2O) 3.3% and oxygen (O2) 4.6%.

[0046] The separation unit (104) increases the purity of CO2 by passing the gas cooled in the first cooling unit (103) through a separation membrane having selective permeability to carbon dioxide (CO2). The gas that passes through the separation membrane in the separation unit (104) has a temperature of 45°C and obtains CO2 gas with 90% purity.

[0047] Since trace amounts of carbon dioxide (CO2) gas are also contained in the residual gas after passing through the separation membrane, the residual gas after passing through the separation membrane is recirculated back to the primary cooling unit (103) to increase the carbon dioxide (CO2) capture rate.

[0048] The secondary cooling section (105) is configured with a cooling cycle arranged in three stages to allow flow through a compressor and a heat exchanger for the operation of cooling the CO2 gas whose temperature has risen while passing through the separation section (104).

[0049] The above secondary cooling unit (105) is configured with a three-stage cooling cycle consisting of a third cooling cycle configured to flow the CO2 gas to a third compressor (33) and a third heat exchanger (43), a fourth cooling cycle configured to flow the gas from the third cooling cycle to a fourth compressor (34) and a fourth heat exchanger (44), and a fifth cooling cycle configured to flow the gas from the fourth cooling cycle to a fifth compressor (35) and a fifth heat exchanger (45).

[0050] CO2 gas that has passed through the three-stage cooling cycle of the above secondary cooling unit (105) is obtained with a temperature of -24 ℃, a pressure of 21.29 bar, and a purity of about 91.3%.

[0051] The above secondary cooling unit (105) is constructed using double-insulated valves and pipes to prevent freezing and blockage of flow within the pipes, etc., between the compressor and heat exchanger that constitute the cooling cycle from low temperature.

[0052] The heat exchangers (41, 42, 43, 44, 45) constituting the first cooling unit (103) and the second cooling unit (105) set a predetermined temperature and error range, and stop the signal or give a signal according to the temperature so that the heat exchangers operate according to the control value, thereby minimizing temperature fluctuations.

[0053] The heat source for the heat exchanger (41, 42, 43, 44, 45) for cooling may be liquid nitrogen (LN2), liquid carbon dioxide (LCO2), water, ethylene, propylene, and propane, but is not necessarily limited thereto.

[0054] The distillation tower (106) distills and separates the CO2 gas cooled in the secondary cooling section (105) to increase the purity of the CO2, thereby producing CO2 in a liquid state from which impurities have been removed.

[0055] The above distillation tower (106) may be selected from either a multi-stage tower or a packed tower, and a packed tower, which has a structure that allows for the use of the entire tower cross-sectional area and has a lower pressure loss and higher separation efficiency compared to a multi-stage tower, may be preferably used.

[0056] In the above distillation tower (106), the theoretical number of stages and the raw material supply stage are optimized through a chemical process simulator, and the actual target process is closely simulated, thereby improving carbon dioxide capture performance and saving energy.

[0057] For example, 65 kg / h of CO2 gas is supplied to the distillation tower (106) to produce CO2 in a liquid state with 46.2 kg / h of CO2, 99.9% purity, 21.29 bar, and -18.1℃. These values ​​meet the fire safety standards for carbon dioxide fire extinguishing systems, and since they can be stored in a low-pressure storage facility, the captured carbon dioxide can be stored more safely than in a high-pressure storage facility.

[0058] In order to improve the carbon dioxide capture rate in the distillation tower (106), the remaining gas after passing through the distillation tower (106) is recirculated back to the separation unit (104) to achieve the maximum capture rate.

[0059] The analysis unit (107) analyzes the carbon dioxide capture performance evaluation results by evaluating the input and product, and can calculate the purity and capture rate of CO2 from the final product obtained from the distillation tower (106) using an analyzer through the carbon dioxide capture performance evaluation.

[0060] The storage tank (108) is a tank for storing liquid CO2 separated from the distillation tower (106), and preferably, a movable storage tank can be constructed.

[0061] The storage tank (108) may be equipped with safety devices, and as safety devices, a level control valve to prevent the formation of overpressure inside the storage tank when liquid CO2 is overfilled into the storage tank and an interlock to block the inflow of liquid CO2 into the storage tank are installed. In addition, a relief valve is installed to prevent the pressure of the vacuum-insulated storage tank from rising due to external factors.

[0062] The interior of the storage tank (108) is maintained at a pressure of 21.29 bar and a temperature of -18.10°C, and for this purpose, pressure and temperature detection and control sensors are installed.

[0063] The control unit (109) is connected to a control panel via a signal system for all of the installation devices of the gas purification unit (102), the primary cooling unit (103), the separation unit (104), the secondary cooling unit (105), the distillation tower (106), and the storage tank (108) that constitute the multi-control system of the carbon dioxide capture complex process. The entire process can be controlled through the control panel, which is connected to the control system and is equipped with multiple operation switches to control the operation of each device in the control room.

[0064] Since temperature and pressure are critical in the multi-control system of the carbon dioxide capture complex process, temperature sensors, pressure sensors, and flow meters are installed as indicators on the piping and equipment of each facility, allowing for visual verification of temperature, pressure, and flow rate values ​​through such sensing and measuring devices.

[0065] The above measuring equipment can be configured in a digital manner so that the signal system is configured to be recognized by the control screen (110) connected to the control panel.

[0066] By selecting a digital method instead of an analog one, numerical values ​​can be checked directly on the equipment, and real-time monitoring is also possible via the control panel. The control panel aggregates all signals in one place, allowing for the verification of temperature, pressure, flow rate, CO2 capture rate, and purity for each piece of equipment. This enables the performance evaluation of the cryogenic capture device.

[0067] The control unit (109) receives information on pressure, temperature, and flow rate detected by a sensor installed in one or more of the gas purification unit (102), the primary cooling unit (103), the separation unit (104), the secondary cooling unit (105), the distillation tower (106), and the storage tank (108), determines whether a preset reference value is reached, and outputs a control signal according to the determination result to control the pressure, temperature, and flow rate to a predetermined level.

[0068] Pressure, temperature, and flow rate are controlled by maintaining and controlling a constant temperature, pressure, and flow rate through a temperature controller, a flow controller, and a pressure regulating valve. In addition, as an example, if an error range is set at a designated temperature and the difference exceeds a certain level, a control signal is triggered to reach that temperature.

[0069] The above control unit (109) is configured so that pressure, temperature, and flow rate can be selected as manual control or automatic control. In manual control mode, control of each facility is not possible from the control unit (109), and in automatic mode, pressure, temperature, and flow rate can be directly controlled through the control panel.

[0070] The above gas purification unit (102), the above primary cooling unit (103), the above separation unit (104), the above secondary cooling unit (105), the above distillation tower (106), and the above storage tank (108) are each connected by piping.

[0071] To control pipe freezing and blockage that occur during the cooling, separation, transport, and storage of carbon dioxide (CO2), the piping and main valves were constructed using double-insulated piping.

[0072] The above-described double-insulated piping is formed by wrapping an insulating material between the inner and outer pipes. Through double insulation, the piping can minimize external condensation and heat loss.

[0073] Since carbon dioxide is a non-flammable gas and chemically stable, the temperature between the double pipes can be controlled using an electric heater.

[0074] In addition, backflow prevention control check valves are installed in the piping between each piece of equipment, and the system includes pressure regulating valves capable of controlling the pressure difference between the upstream and downstream ends, as well as safety relief valves. Among these valves, vacuum insulation valves are used to reduce low-temperature loss and improve the quality of liquefied carbon dioxide under cryogenic conditions, while an automatic control system enhances safety and maintenance capabilities.

[0075] In the separation section (104), distillation tower (106), and storage tank (108), the water level is determined by the level gauge, and if it exceeds a certain level, a signal is automatically applied to vent a portion or stop the supply. Additionally, the temperature and pressure at the upstream and downstream ends are adjusted through temperature, pressure, and flow rate controllers to maintain and control the pressure and temperature, thereby reducing temperature and pressure fluctuations and increasing stability.

[0076] The multi-control method of the multi-control system of the carbon dioxide capture composite process of the present invention is as shown in FIGS. 3 and 4.

[0077] FIG. 3 is a flowchart of a multi-control method for a carbon dioxide capture composite process according to an embodiment of the present invention, and pressure, temperature, and flow rate can be controlled in a multi-control system for a carbon dioxide capture composite process, and control is possible according to set values.

[0078] As shown in FIG. 3, the process comprises a first cooling step (S110), a first judgment step (S111), a membrane step (S120), a second cooling step (S130), a second judgment step (S131), a distillation tower step, and a storage step (S140).

[0079] The first cooling step (S110) is a step of cooling the exhaust gas by passing it through the first cooling unit (103). The exhaust gas introduced is cooled by passing it through a two-stage cooling cycle that constitutes the first cooling unit (103).

[0080] Prior to the first cooling step (S110) above, a purification step can be performed to purify the exhaust gas into a gas purification unit to remove dust and moisture contained in the exhaust gas.

[0081] The first judgment step (S111) is a step of determining whether the temperature and pressure of the gas cooled in the first cooling step (S110) satisfy a preset standard range.

[0082] If the pressure of the gas that has undergone the first cooling step (S110) is 3 bar or higher and the temperature is 5°C or lower, the gas is supplied to the first cooling unit (103) again to perform the first cooling step again.

[0083] If the temperature and pressure of the cooled gas in the first judgment step (S11) satisfy the reference range, a separation membrane step (S120) is performed in which the gas is injected into the separation unit (104) and the CO2 gas is separated through the separation membrane.

[0084] The second cooling step (S130) cools the CO2 gas from the membrane step (S120) through a three-stage cooling cycle that constitutes the second cooling unit (105).

[0085] The second judgment step (S131) ​​determines whether the temperature and pressure of the gas cooled in the second cooling step (S130) satisfy a preset standard range before injecting the CO2 gas cooled through the second cooling step (S130) into the distillation tower.

[0086] If the pressure of the gas that has undergone the second cooling step (S130) is 21 bar or higher and the temperature is -24°C or lower, the gas is supplied to the second cooling unit (105) again to perform the second cooling step (S130) again.

[0087] The distillation tower step and storage step (S140) is a distillation tower step in which, when the temperature and pressure of the gas cooled in the second judgment step satisfy the reference range, the gas is injected into the distillation tower (106) to distill and separate it to produce liquid CO2 with impurities removed, and a storage step in which the liquid CO2 separated from the distillation tower (106) after passing through the distillation tower step is stored in a storage tank (108).

[0088] When the liquid CO2 separated from the distillation tower (106) after passing through the above distillation tower step satisfies the criteria of a preset standard value of 21 bar or higher and a temperature of -18℃ or lower, it is stored in a storage tank.

[0089] FIG. 4 is a flowchart illustrating a method for controlling the circulation of residual gas in a multi-control method of a carbon dioxide capture composite process according to one embodiment of the present invention, and includes a first cooling step (S210), a membrane step (S220), a second cooling step (S230), and a distillation tower step (S240) as shown.

[0090] The above first cooling step (S210), membrane step (S220), second cooling step (S230), and distillation column step (S240) are performed in the same way as the first cooling step (S110), membrane step (S120), second judgment step (S131), distillation column step, and storage step (S140) described above.

[0091] The first cooling step (S210) is a step of cooling the exhaust gas by passing it through the first cooling unit (103). The exhaust gas introduced is cooled by passing it through a two-stage cooling cycle that constitutes the first cooling unit (103).

[0092] The separation membrane step (S220) injects gas into the separation unit (104) and separates CO2 gas through the separation membrane.

[0093] The first residual gas circulation step (S211) supplies the residual gas, after passing through the membrane in the membrane step (S220), back to the first cooling unit (103) to perform the first cooling step (S210) again so that the carbon dioxide remaining in the residual gas is captured.

[0094] Through the first residual gas circulation step (S211), approximately 17% of the CO2 contained in the residue in the membrane is recirculated to the membrane for additional separation and the CO2 capture rate is increased.

[0095] The second cooling step (S230) cools the CO2 gas from the membrane step (S220) through a three-stage cooling cycle that constitutes the second cooling unit (105).

[0096] The distillation tower step (S240) injects the gas cooled through the secondary cooling step (S230) into the distillation tower (106) to distill and separate it, thereby producing liquid CO2 from which impurities have been removed.

[0097] The second residual gas circulation step (S241) allows the residual gas, after passing through the distillation tower (106) in the distillation tower step (S240), to be supplied back to the separation unit (104) so ​​that the membrane step (S220), the second cooling step (S230), and the distillation tower step (S240) can be performed sequentially.

[0098] Since the residue after passing through the distillation column contains 19.99 bar, -29.22°C, and 72.6% CO2, the residue gas is secondarily circulated through a membrane via the second residue gas circulation step (S241), thereby achieving high purity through CO2 separation and saving energy required for subsequent compressor and cooling.

[0099] The carbon dioxide capture rate can be calculated using the supplied flue gas and the liquid carbon dioxide from the distillation tower, and the liquid carbon dioxide (CO2) gas from the distillation tower step (S240) has a CO2 purity of 99.9% or higher and a CO2 capture rate of 95% or higher.

[0100] When the final captured CO2 purity is 99.9% or higher and the CO2 capture rate is 95% or higher, the residual gas from the distillation tower is not further circulated and the process is stopped.

[0101] In the multi-control method of the carbon dioxide capture complex process as illustrated in Fig. 4, the circulation of residual CO2 flow rate of the residual gas passing through the membrane and distillation column can be controlled through the residual gas circulation control method, and the CO2 flow rate can be checked through each flow meter from the flue gas inlet to the final process after the distillation column, and the control can be made to optimally achieve the final purity and capture rate.

[0102] As previously described, the multi-control system of the carbon dioxide capture composite process of the present invention is configured with a primary cooling unit consisting of a two-stage cooling cycle and a secondary cooling unit consisting of a three-stage cooling cycle to efficiently capture carbon dioxide. In addition, to prevent equipment damage caused by cooling, the piping and other components are constructed with a double-insulated structure to enable stable operation of the carbon dioxide capture process. Furthermore, a control panel is configured to allow for automatic process control, and the system is composed of an automated system that facilitates the control of flow rate, temperature, and pressure to achieve an optimal carbon dioxide capture rate. Explanation of the symbols

[0103] 11, 12, 13, 14, 15, 16, 17: Check valve 21: Gas purification filter 22: Water-gas separator 31: First compressor 32: 2nd Compressor 33: 3rd Compressor 34: 4th compressor 35: 5th compressor 41: 1st heat exchanger 42: 2nd heat exchanger 43: 3rd heat exchanger 44: 4th heat exchanger 45: 5th heat exchanger 101: Flue gas 102: Gas purification unit 103: Primary cooling unit 104: Separator 105: Secondary cooling section 106 : Distillation column 107 : Analysis unit 108 : Storage tank 109 : Control unit 110 : Control screen

Claims

Claim 1 A gas purification unit for removing impurities, including moisture, contained in the incoming flue gas; a primary cooling unit with a cooling cycle arranged in two stages, configured to flow through a compressor and a heat exchanger to cool the gas that has passed through the gas purification unit; a separation unit for separating CO2 gas from the gas cooled in the primary cooling unit; a secondary cooling unit with a cooling cycle arranged in three stages, configured to flow through a compressor and a heat exchanger to cool the CO2 gas separated through the separation unit; a distillation tower for producing liquid CO2 from which impurities have been removed by distilling and separating the CO2 gas cooled in the secondary cooling unit to increase CO2 purity; an analysis unit for calculating the purity and capture rate of CO2 using an analyzer from the final product obtained from the distillation tower; and a storage tank for storing the liquid CO2 separated from the distillation tower. A multi-control system for a carbon dioxide capture complex process comprising: a control unit for controlling the operation, pressure, temperature, and flow rate of one or more of the gas purification unit, the primary cooling unit, the separation unit, the secondary cooling unit, the distillation tower, and the storage tank; wherein the residual gas after passing through the separation membrane in the separation unit is recirculated back to the primary cooling unit to increase the CO2 capture rate, and the residual gas after passing through the distillation tower is recirculated back to the separation unit. Claim 2 A multi-control system for a carbon dioxide capture combined process, characterized in that, in claim 1, the gas purification unit comprises: a gas purification filter for removing particulate impurities, such as dust contained in the incoming flue gas; and a gas-water separator for removing condensate by condensing moisture (H2O) contained in the exhaust gas after passing through the gas purification filter. Claim 3 A multi-control system for a carbon dioxide capture composite process according to claim 1, wherein the primary cooling unit comprises a two-stage cooling cycle consisting of: a first cooling cycle configured to flow the gas through a first compressor and a first heat exchanger; and a second cooling cycle configured to flow the gas from the first cooling cycle through a second compressor and a second heat exchanger. Claim 4 A multi-control system for a carbon dioxide capture composite process according to claim 1, wherein the separation unit separates CO2 gas by passing the gas cooled in the primary cooling unit through a separation membrane. Claim 5 delete Claim 6 A multi-control system for a carbon dioxide capture composite process according to claim 1, wherein the secondary cooling unit comprises a third cooling cycle configured to flow the CO2 gas through a third compressor and a third heat exchanger; a fourth cooling cycle configured to flow the gas from the third cooling cycle through a fourth compressor and a fourth heat exchanger; and a fifth cooling cycle configured to flow the gas from the fourth cooling cycle through a fifth compressor and a fifth heat exchanger; characterized in that the secondary cooling unit comprises a three-stage cooling cycle. Claim 7 A multi-control system for a carbon dioxide capture complex process according to claim 1, wherein the distillation tower is selected from either a multi-stage tower or a packed tower. Claim 8 delete Claim 9 A multi-control system for a carbon dioxide capture complex process, wherein, in claim 1, the analysis unit identifies and analyzes the results of the carbon dioxide capture performance evaluation through the evaluation of inputs and products. Claim 10 A multi-control system for a carbon dioxide capture complex process according to claim 1, wherein the storage tank is a movable mobile storage tank and is equipped with a water level control valve for preventing the formation of overpressure inside the storage tank when liquefied CO2 is overfilled inside the storage tank; and an interlock for blocking the inflow of liquefied CO2 into the storage tank. Claim 11 A multi-control system for a carbon dioxide capture complex process, characterized in that, in item 10, the storage tank is equipped with a relief valve to prevent pressure rise. Claim 12 A multi-control system for a carbon dioxide capture complex process according to claim 1, wherein the control unit receives pressure, temperature, and flow rate detected by sensors installed in one or more of the gas purification unit, the primary cooling unit, the separation unit, the secondary cooling unit, the distillation tower, and the storage tank, determines whether a preset reference value is reached, and outputs a control signal according to the determination result to control to a predetermined pressure, temperature, and flow rate. Claim 13 A multi-control system for a carbon dioxide capture complex process, characterized in that, in Clause 12, the pressure, temperature, and flow rate in the control unit are controlled by manual and automatic control. Claim 14 A purification step for purifying exhaust gas in a gas purification unit; a first cooling step for cooling exhaust gas through a first cooling unit; a first judgment step for determining whether the temperature and pressure of the gas cooled in the first cooling step satisfy a preset standard range; a membrane step for separating CO2 gas by injecting the gas into a separation unit and passing it through a membrane if the temperature and pressure of the gas cooled in the first judgment step satisfy the standard range; a second cooling step for cooling the CO2 gas from the membrane step through a second cooling unit; a second judgment step for determining whether the temperature and pressure of the gas cooled in the second cooling step satisfy a preset standard range; and a distillation tower step for producing liquid CO2 with impurities removed by injecting the gas into a distillation tower and distilling and separating it if the temperature and pressure of the gas cooled in the second judgment step satisfy the standard range. A multi-control method for a carbon dioxide capture complex process, comprising: a storage step of storing liquefied CO2 separated from the distillation tower after passing through the distillation tower step in a storage tank; wherein, in the membrane step, the residual gas is supplied again to a primary cooling unit to re-perform the primary cooling step to increase the CO2 capture rate, and in the distillation tower step, the residual gas is supplied again to a separation unit to sequentially re-perform the membrane step, the secondary cooling step, and the distillation tower step. Claim 15 A multi-control method for a carbon dioxide capture composite process according to claim 14, characterized in that if the temperature and pressure of the cooled gas in the first judgment step do not fall within a reference range, the gas is supplied back to the first cooling unit to re-perform the first cooling step. Claim 16 A multi-control method for a carbon dioxide capture complex process according to claim 14, characterized in that if the temperature and pressure of the cooled gas in the second judgment step do not fall within a reference range, the gas is supplied again to a secondary cooling unit to re-perform the secondary cooling step. Claim 17 delete Claim 18 delete Claim 19 A multi-control method for a carbon dioxide capture complex process according to claim 14, characterized in that when the liquefied CO2 gas from the distillation tower stage has a CO2 purity of 99.9% or higher and a CO2 capture rate of 95% or higher, the residual gas from the distillation tower is not further circulated.

Images