Carbon dioxide separation device

Abstract

The present invention provides a carbon dioxide separation device that suppresses abnormal combustion and misfires in the combustor, and also improves the performance of the carbon dioxide separation device itself. [Solution] A carbon dioxide separation apparatus 1 comprising: a first membrane separator 3 for introducing a raw material gas containing carbon dioxide; a combustor 6 provided downstream of the first membrane separator 3 for burning the first non-permeable gas; a second membrane separator 8 provided downstream of the combustor 6; a compressor 9 for supplying the combustion gas to the second membrane separator 8; and at least one third membrane separator 13 provided downstream of the second membrane separator 8.

Description

[[Technical Field]]

[0001] The present invention relates to a carbon dioxide separation apparatus. [[Background Art]]

[0002] For example, as a technique for separating and recovering carbon dioxide (CO₂) from natural gas containing methane (CH₄), there is known a carbon dioxide separation apparatus comprising: a raw material gas introduction line for introducing a raw material gas containing carbon dioxide; a first membrane separator connected to an end of said raw material gas introduction line, for membrane-separating carbon dioxide from said raw material gas; a first permeate gas discharge line for discharging a first permeate gas that has permeated through membrane separation in said first membrane separator; a first non-permeate gas discharge line for discharging a first non-permeate gas that has not permeated through membrane separation in said first membrane separator; a second membrane separator provided downstream of said first membrane separator, for membrane-separating carbon dioxide from the first non-permeate gas; a second permeate gas discharge line for discharging a second permeate gas that has permeated through membrane separation in said second membrane separator; and a second permeate gas return line branched from a part of said second permeate gas discharge line, for returning the second permeate gas to said raw material gas or said first non-permeate gas (see, for example, Patent Document 1). [[Prior Art Literature]] [[Patent Literature]]

[0003] [[Patent Document 1]] Japanese Unexamined Patent Application Publication No. 2016-93767 [[Summary of the Invention]] [[Problem to be Solved by the Invention]]

[0004] In a system for recovering carbon dioxide discharged from a combustor such as a combustor, assuming that a carbon dioxide recovery system is installed downstream of the combustor, the pressure (back pressure) on the downstream side of the combustor increases due to the influence of pressure loss and the like, which may cause abnormal combustion, misfire, or the like in the combustor, and can become a cause of problems. Therefore, process design is required to prevent the back pressure of the combustor from increasing excessively.

[0005] This invention has been made in view of the above circumstances, and aims to provide a carbon dioxide separation device that can suppress abnormal combustion and misfires in the combustor, and further improve the performance of the carbon dioxide separation device itself. Ultimately, this will contribute to energy efficiency. [Means for solving the problem]

[0006] The present invention has the following aspects. [1] A raw material gas introduction line that introduces a raw material gas containing carbon dioxide, The end of the raw material gas introduction line is connected to a first membrane separator into which the raw material gas is introduced, A first permeate gas discharge line for discharging the first permeate gas that has permeated through the membrane separation of the first membrane separator, A first non-permeable gas discharge line for discharging the first non-permeable gas that is not permeated by the membrane separation of the first membrane separator, A combustor is provided downstream of the first membrane separator and burns the first permeate gas, A combustion gas discharge line is connected to the combustor and discharges the combustion gas obtained by burning the first permeate gas in the combustor, A second membrane separator is provided downstream of the combustor and connected to the combustion gas discharge line, A compressor is provided in the middle of the combustion gas discharge line and supplies the combustion gas to the second membrane separator, A second permeate gas discharge line for discharging the second permeate gas that has permeated through the membrane separation of the second membrane separator, A second non-permeable gas discharge line discharges the second non-permeable gas that is not permeated by the membrane separation of the second membrane separator and supplies it to the first membrane separator, A carbon dioxide separation device equipped with the following features.

[0007] According to the above embodiment, by arranging the compressor downstream of the combustor, it is possible to suppress abnormal combustion and misfires in the combustor, and furthermore, to expect a combination of effects such as improved performance of the carbon dioxide separation device itself.

[0008] [2] A first vacuum pump provided in the middle of the second permeate gas discharge line, which supplies the second permeate gas to the second membrane separator, A third membrane separator is provided downstream of the second membrane separator and connected to the second permeate gas discharge line, and includes at least one third membrane separator. A third permeate gas discharge line for discharging the third permeate gas that has permeated through the membrane separation of the third membrane separator, A third non-permeable gas discharge line discharges the third non-permeable gas that is not permeated by the membrane separation of the third membrane separator and supplies it to the combustion gas discharge line, The carbon dioxide separation apparatus according to [1], comprising a second vacuum pump installed in the middle of the third permeate gas discharge line.

[0009] According to the above embodiment, by arranging the compressor downstream of the combustor, it is possible to suppress abnormal combustion and misfires in the combustor, and furthermore, to expect a combination of effects such as improved performance of the carbon dioxide separation device itself.

[0010] [3] The carbon dioxide separation apparatus according to [1], wherein when the carbon monoxide concentration downstream of the combustor is below a predetermined value and the oxygen concentration upstream of the combustor is below a predetermined value, the compressor reduces the pressure of the combustion gas supplied to the second membrane separator.

[0011] According to the above embodiment, adverse effects on the combustor can be suppressed by increasing the flame temperature, and the oxygen concentration can be kept constant.

[0012] [4] The carbon dioxide separation apparatus according to [1], wherein the compressor increases the pressure of the combustion gas supplied to the second membrane separator when the oxygen concentration upstream of the combustor is above a predetermined value.

[0013] According to the above embodiment, adverse effects on the combustor can be suppressed by increasing the flame temperature, and the oxygen concentration can be kept constant. [Effects of the Invention]

[0014] According to the present invention, it is possible to provide a carbon dioxide separation device that can suppress abnormal combustion and misfiring in a combustor and further improve the performance of the carbon dioxide separation device itself. [BRIEF DESCRIPTION OF THE DRAWINGS]

[0015] [Figure 1] FIG. 1 is a schematic diagram showing the carbon dioxide separation device according to the first embodiment of the present invention. [Figure 2] FIG. 1 is a flowchart of a carbon dioxide separation method using the carbon dioxide separation device according to the first embodiment of the present invention. [Figure 3] FIG. 2 is a schematic diagram showing the carbon dioxide separation device according to the second embodiment of the present invention. [Figure 4] FIG. 2 is a flowchart of a carbon dioxide separation method using the carbon dioxide separation device according to the second embodiment of the present invention. [Figure 5] FIG. 3 is a schematic diagram showing the carbon dioxide separation device according to the third embodiment of the present invention. [Figure 6] FIG. 4 is a schematic diagram showing the carbon dioxide separation device according to the fourth embodiment of the present invention. [MODE FOR CARRYING OUT THE INVENTION]

[0016] Embodiments of the present invention will be described below.

[0017] [Carbon Dioxide Separation Device] (First Embodiment) FIG. 1 is a schematic diagram showing the carbon dioxide separation device of the present embodiment. As shown in FIG. 1, the carbon dioxide separation device 1 of the present embodiment includes a raw material gas introduction line 2, a first membrane separator 3, a first permeated gas discharge line 4, a first non-permeated gas discharge line 5, a combustor 6, a combustion gas discharge line 7, a second membrane separator 8, a compressor 9, a second permeated gas discharge line 10, and a second non-permeated gas discharge line 11. In addition, the carbon dioxide separation device 1 of the present embodiment preferably further includes a first vacuum pump 12, a third membrane separator 13, a third permeated gas discharge line 14, a third non-permeated gas discharge line 15, and a second vacuum pump 16.

[0018] The raw material gas introduction line (first raw material gas introduction line) 2 is for introducing a raw material gas containing carbon dioxide into the first membrane separator 3.

[0019] The first membrane separator 3 is connected to the end of the raw material gas introduction line 2 and is used to introduce the raw material gas. The first membrane separator 3 is also connected to the second impermeable gas discharge line 11 and is used to separate the second impermeable gas supplied from the second membrane separator 8 via the second impermeable gas discharge line 11. A carbon dioxide separator equipped with a general carbon dioxide separation membrane can be used as the first membrane separator 3.

[0020] The first permeate gas discharge line 4 is connected to the first membrane separator 3 and is used to discharge the first permeate gas that has permeated through the membrane separation of the first membrane separator 3 from the first membrane separator 3.

[0021] The first non-permeable gas discharge line 5 is connected to the first membrane separator 3 and is for discharging the first non-permeable gas that is not permeated by the membrane separation of the first membrane separator 3.

[0022] The combustor 6 is located downstream of the first membrane separator 3 and is connected to the first non-permeable gas discharge line 5 for burning the first permeable gas.

[0023] The combustion gas discharge line 7 is connected to the combustor 6 and is used to discharge the combustion gas obtained by burning the first permeate gas in the combustor 6 to the downstream side of the combustor 6.

[0024] The second membrane separator 8 is located downstream of the combustor 6 and is connected to the combustion gas discharge line 7. The second membrane separator 8 is used to separate the combustion gas supplied from the combustor 6 using a membrane. A carbon dioxide separator equipped with a general carbon dioxide separation membrane can be used as the second membrane separator 8.

[0025] The compressor 9 is installed in the middle of the combustion gas discharge line 7 and is for supplying combustion gas to the second membrane separator 8.

[0026] The second permeate gas discharge line 10 is connected to the second membrane separator 8 and is used to discharge the second permeate gas that has permeated through the membrane separation of the second membrane separator 8.

[0027] The second non-permeable gas discharge line 11 is connected to the second membrane separator 8 and is intended to discharge the second non-permeable gas that is not permeated by the membrane separation of the second membrane separator 8 and supply it to the first membrane separator 3.

[0028] The first vacuum pump 12 is installed in the middle of the second permeate gas discharge line 10 and is for supplying the second permeate gas to the second membrane separator 8.

[0029] The third membrane separator 13 is located downstream of the second membrane separator 8 and is connected to the second permeate gas discharge line 10. The third membrane separator 13 is also used for membrane separation of the second permeate gas supplied from the second membrane separator 8. A carbon dioxide separator equipped with a general carbon dioxide separation membrane can be used as the third membrane separator 13.

[0030] The third permeate gas discharge line 14 is connected to the third membrane separator 13 and is used to discharge the third permeate gas that has permeated through the membrane separation of the third separator 13 from the third separator 13.

[0031] The third non-permeable gas discharge line 15 is connected to the third membrane separator 13 and is intended to discharge the third non-permeable gas that is not permeated by the membrane separation of the third membrane separator 13 and supply it to the combustion gas discharge line 7.

[0032] The second vacuum pump 16 is installed in the middle of the third permeate gas discharge line 14 and is used to discharge the third permeate gas from the third separator 13.

[0033] The control logic of the carbon dioxide separation device of this embodiment will now be explained. When the carbon monoxide concentration downstream of the combustor 6 is below a predetermined value, and the oxygen concentration upstream of the combustor 6 is below a predetermined value, the compressor 9 is activated to reduce the pressure of the combustion gas supplied to the second membrane separator 8. This suppresses adverse effects on the combustor 6 due to an increase in flame temperature, while also maintaining a constant oxygen concentration.

[0034] Furthermore, if the oxygen concentration upstream of the combustor 6 exceeds a predetermined value, the compressor 9 is activated to increase the pressure of the combustion gas supplied to the second membrane separator 8. This suppresses adverse effects on the combustor 6 due to the rise in flame temperature and maintains a constant oxygen concentration.

[0035] Figure 2 is a flowchart of the carbon dioxide separation method using the carbon dioxide separation apparatus of this embodiment. The power to the carbon dioxide separator 1 is turned on, and the carbon dioxide separator 1 is activated (Step: S1). Then, the combustor 6 and compressor 9 start up (Step: S2).

[0036] Next, downstream of the combustor 6, the target value of the combustion gas pressure supplied to the second membrane separator 8 is set to an arbitrary value (step: S3).

[0037] Check whether to continue controlling the pressure of the combustion gas supplied to the second membrane separator 8 (Step: S4). If control of the pressure of the combustion gas supplied to the second membrane separator 8 is to be continued, measure the pressure of the combustion gas supplied to the second membrane separator 8 and update the target value of the pressure of the combustion gas supplied to the second membrane separator 8 (Step: S5).

[0038] Next, the difference between the measured pressure of the combustion gas supplied to the second membrane separator 8 and the target pressure of the combustion gas supplied to the second membrane separator 8 is calculated (Step: S6). The pressure of the combustion gas supplied to the second membrane separator 8 is calculated according to the difference, and the compressor 9 is controlled to achieve that pressure (Step: S7).

[0039] Next, the pressure of the combustion gas supplied to the second membrane separator 8 is measured, and the target value of the combustion gas pressure supplied to the second membrane separator 8 is updated (Step: S8).

[0040] Downstream of the combustor 6, it is checked whether the pressure of the combustion gas supplied to the second membrane separator 8 is greater than threshold 1 (Step: S9).

[0041] If the pressure of the combustion gas supplied to the second membrane separator 8 downstream of the combustor 6 is less than threshold 1, the target value of the pressure of the combustion gas supplied to the second membrane separator 8 downstream of the combustor 6 is updated (K3), and the process returns to step S4 (step S10).

[0042] On the other hand, if the pressure of the combustion gas supplied to the second membrane separator 8 downstream of the combustor 6 is greater than threshold 1, the oxygen concentration is measured upstream of the combustor 6 and the oxygen concentration supplied to the combustor 6 is updated (step: S11).

[0043] Next, the carbon monoxide concentration is measured downstream of the combustor 6, and the carbon monoxide concentration emitted from the combustor 6 is updated (Step: S12).

[0044] Downstream of the combustor 6, it is checked whether the pressure of the combustion gas supplied to the second membrane separator 8 is greater than threshold 2 (Step: S13).

[0045] If the pressure of the combustion gas supplied to the second membrane separator 8 downstream of the combustor 6 is greater than threshold 2, the target value of the pressure of the combustion gas supplied to the second membrane separator 8 downstream of the combustor 6 is updated (K2), and the process returns to step S4 (step S14).

[0046] If the pressure of the combustion gas supplied to the second membrane separator 8 downstream of the combustor 6 is less than threshold 2, check whether the oxygen concentration supplied to the second membrane separator 8 upstream of the combustor 6 is greater than threshold 3 (step: S15). If the oxygen concentration supplied to the second membrane separator 8 upstream of the combustor 6 is less than threshold 3, update the target value of the combustion gas pressure supplied to the second membrane separator 8 downstream of the combustor 6 (K3), and return to step: S4 (step: S16).

[0047] On the other hand, if the oxygen concentration supplied to the second membrane separator 8 upstream of the combustor 6 is greater than the threshold 3, the process returns to step S4.

[0048] In step S4, if the control of the combustion gas pressure supplied to the second membrane separator 8 is not continued, a decision is made as to whether or not to turn off the power to the carbon dioxide separator 1 (step S17). If the power to the carbon dioxide separator 1 is not turned off, the process returns to step S4.

[0049] When the power to the carbon dioxide separator 1 is turned off, the combustor 6 and compressor 9 are stopped (step: S18), and the operation of the carbon dioxide separator 1 is stopped (step: S19).

[0050] According to the carbon dioxide separation device 1 of this embodiment, by arranging the compressor 9 downstream of the combustor 6, it is possible to suppress abnormal combustion and misfires of the combustor 6, and furthermore, improve the performance of the carbon dioxide separation device 1 itself, thus achieving a combination of effects.

[0051] (Second embodiment) Figure 3 is a schematic diagram showing the carbon dioxide separation apparatus of this embodiment. In Figure 3, components identical to those shown in Figure 1 are denoted by the same reference numerals, and their descriptions are omitted. As shown in Figure 3, the carbon dioxide separation apparatus 100 of this embodiment includes, in addition to the carbon dioxide separation apparatus 1 described above, a fourth membrane separator 101, a second raw material gas introduction line 102, a fourth permeate gas discharge line 103, and a third vacuum pump 104.

[0052] The fourth membrane separator 101 is connected to the end of the second raw material gas introduction line 102 and is used to introduce the raw material gas. The fourth membrane separator 101 is also connected to the end of the first raw material gas introduction line 2 and is used to pre-separate nitrogen contained in the raw material gas and supply the nitrogen-free raw material gas to the first membrane separator 3 via the first raw material gas introduction line 2. By pre-separating nitrogen contained in the raw material gas, the carbon dioxide recovery rate is improved.

[0053] The fourth permeate gas discharge line 103 is connected to the fourth membrane separator 101 and is used to discharge the fourth permeate gas (nitrogen) that has permeated through the membrane separation of the fourth membrane separator 101 from the fourth membrane separator 101.

[0054] The third vacuum pump 104 is installed in the middle of the fourth permeate gas discharge line 103 and is used to discharge the fourth permeate gas (nitrogen) from the fourth membrane separator 101.

[0055] The control logic of the carbon dioxide separation device of this embodiment will now be explained. When the carbon dioxide concentration downstream of the combustor 6 is below a predetermined value, and the oxygen concentration upstream of the combustor 6 is below a predetermined value, the compressor 9 is activated to reduce the pressure of the combustion gas supplied to the second membrane separator 8. This suppresses adverse effects on the combustor 6 due to an increase in flame temperature, while also maintaining a constant oxygen concentration.

[0056] Furthermore, if the oxygen concentration upstream of the combustor 6 exceeds a predetermined value, the compressor 9 is activated to increase the pressure of the combustion gas supplied to the second membrane separator 8. This suppresses adverse effects on the combustor 6 due to the rise in flame temperature and maintains a constant oxygen concentration.

[0057] Figure 4 is a flowchart of the carbon dioxide separation method using the carbon dioxide separation apparatus of this embodiment. The power to the carbon dioxide separator 100 is turned on, and the carbon dioxide separator 100 is activated (Step: S21). Then, the combustor 6 starts up (Step: S22).

[0058] Next, start the compressor 9 and the third vacuum pump 104 (step: S23).

[0059] Next, the oxygen concentration is measured upstream of the combustor 6, and the oxygen concentration supplied to the combustor 6 is updated (Step: S24).

[0060] Check whether to continue controlling the oxygen pressure supplied to the combustor 6 (Step: S25). If the control of the oxygen pressure supplied to the combustor 6 is to be continued, measure the oxygen concentration upstream of the combustor 6 and update the oxygen concentration supplied to the combustor 6 (Step: S26).

[0061] Next, the difference between the measured oxygen pressure supplied to the combustor 6 and the target oxygen pressure supplied to the combustor 6 is calculated (Step: S27).

[0062] Next, the concentration of carbon monoxide supplied to the second membrane separator 8 is measured downstream of the combustor 6, and the concentration of carbon monoxide supplied to the second membrane separator 8 is updated (Step: S28).

[0063] Downstream of the combustor 6, it is checked whether the concentration of carbon monoxide supplied to the second membrane separator 8 is greater than threshold 2 (Step: S29).

[0064] If the carbon monoxide concentration supplied to the second membrane separator 8 is greater than threshold 2, the difference between the measured pressure of the carbon monoxide concentration supplied to the second membrane separator 8 and the target pressure of the carbon monoxide concentration supplied to the second membrane separator 8 is calculated, the pressure of the carbon monoxide concentration supplied to the second membrane separator 8 corresponding to the difference is calculated, the compressor 9 is controlled to achieve that pressure, and the process returns to step S25 (step S30).

[0065] If the carbon monoxide concentration supplied to the second membrane separator 8 is less than threshold 2, the oxygen concentration supplied to the combustor 6 is measured upstream of the combustor 6 to confirm whether the oxygen concentration supplied to the combustor 6 is less than the target value (Step: S31).

[0066] If the oxygen concentration supplied to the combustor 6 is less than the target value, the difference between the measured pressure of the carbon monoxide concentration supplied to the second membrane separator 8 and the target pressure of the carbon monoxide concentration supplied to the second membrane separator 8 is calculated, the pressure of carbon dioxide supplied to the second membrane separator 8 corresponding to the difference is calculated, the compressor 9 is controlled to achieve that pressure, and the process returns to step S25 (step S32).

[0067] If the oxygen concentration supplied to the combustor 6 is greater than the target value, the difference between the measured pressure of the carbon monoxide concentration supplied to the second membrane separator 8 and the target pressure of the carbon monoxide concentration supplied to the second membrane separator 8 is calculated. The pressure of the carbon monoxide concentration supplied to the second membrane separator 8 corresponding to the difference is calculated, the compressor 9 is controlled to achieve that pressure, and the process returns to step S25.

[0068] In step S25, if the control of the oxygen pressure supplied to the second membrane separator 8 is not continued, a decision is made as to whether or not to turn off the power to the carbon dioxide separator 100 (step S33). If the power to the carbon dioxide separator 100 is not turned off, the process returns to step S25.

[0069] To turn off the power to the carbon dioxide separator 100, the combustor 6 is stopped (step: S34), the compressor 9 and the third vacuum pump 104 are stopped (step: S35), and the operation of the carbon dioxide separator 100 is stopped (step: S36).

[0070] According to the carbon dioxide separation apparatus 100 of this embodiment, the recovery rate of carbon dioxide is improved by pre-separating nitrogen contained in the raw gas using the fourth membrane separator 101.

[0071] (Third embodiment) Figure 5 is a schematic diagram showing the carbon dioxide separation apparatus of this embodiment. In Figure 5, components identical to those shown in Figure 1 are denoted by the same reference numerals, and their descriptions are omitted. As shown in Figure 5, the carbon dioxide separation apparatus 200 of this embodiment includes, in addition to the carbon dioxide separation apparatus 1 described above, a fifth membrane separator 201, a fifth permeate gas discharge line 202, a fifth non-permeate gas discharge line 203, and a fourth vacuum pump 204.

[0072] The fifth membrane separator 201 is located downstream of the third membrane separator 13 and is connected to the third permeate gas discharge line 14. The fifth membrane separator 201 is also used for membrane separation of the third permeate gas supplied from the third membrane separator 13. A carbon dioxide separator equipped with a general carbon dioxide separation membrane can be used as the fifth membrane separator 201.

[0073] The fifth permeate gas discharge line 202 is connected to the fifth membrane separator 201 and is used to discharge the fifth permeate gas that has permeated through the membrane separation of the fifth membrane separator 201 from the fifth membrane separator 201.

[0074] The fifth non-permeable gas discharge line 203 is connected to the fifth membrane separator 201 and is intended to discharge the fifth non-permeable gas that is not permeated by the membrane separation of the fifth membrane separator 201 and supply it to the combustion gas discharge line 7.

[0075] The fourth vacuum pump 204 is located in the middle of the fifth permeate gas discharge line 202 and is used to discharge the fifth permeate gas from the fifth membrane separator 201.

[0076] According to the carbon dioxide separation apparatus 200 of this embodiment, the carbon dioxide recovery rate can be further increased by providing a fifth membrane separator 201.

[0077] (Fourth embodiment) Figure 6 is a schematic diagram showing the carbon dioxide separation apparatus of this embodiment. In Figure 6, components identical to those shown in Figures 1, 3, and 5 are denoted by the same reference numerals, and their descriptions are omitted. As shown in Figure 6, the carbon dioxide separation apparatus 300 of this embodiment includes, in addition to the carbon dioxide separation apparatus 200 described above, a fourth membrane separator 101, a second raw material gas introduction line 102, a fourth permeate gas discharge line 103, and a third vacuum pump 104.

[0078] According to the carbon dioxide separation apparatus 300 of this embodiment, by providing a fourth membrane separator 101 and a fifth membrane separator 201, nitrogen contained in the raw gas can be separated in advance, thereby increasing the carbon dioxide recovery rate.

[0079] Although embodiments of the present invention have been described in detail above, the present invention is not limited to the above embodiments, and various modifications and changes are possible within the scope of the gist of the present invention as described in the claims. [Explanation of Symbols]

[0080] 1,100,200,300 Carbon Dioxide Separator 2. Raw material gas introduction line 3 First membrane separator 4. First permeable gas discharge line 5. First non-permeable gas discharge line 6 Combustor 7. Combustion gas exhaust line 8 Second membrane separator 9 Compressor 10. Second permeable gas discharge line 11. Second impermeable gas discharge line 12. First Vacuum Pump 13 Third membrane separator 14. Third permeable gas discharge line 15. Third non-permeable gas discharge line 16. Second Vacuum Pump 101 4th membrane separator 102 Second raw material gas introduction line 103 Fourth Permeable Gas Discharge Line 104 Third Vacuum Pump 201 5th membrane separator 202 Fifth Permeate Gas Emission Line 203 No. 5 Impermeable Gas Emission Line 204. Fourth Vacuum Pump

Claims

1. A raw material gas introduction line that introduces raw material gas containing carbon dioxide, The end of the raw material gas introduction line is connected to a first membrane separator into which the raw material gas is introduced, A first permeate gas discharge line for discharging the first permeate gas that has permeated through the membrane separation of the first membrane separator, A first non-permeable gas discharge line discharges the first non-permeable gas that is not permeated by the membrane separation of the first membrane separator, A combustor is provided downstream of the first membrane separator and burns the first permeate gas, A combustion gas discharge line is connected to the combustor and discharges the combustion gas obtained by burning the first permeate gas in the combustor, A second membrane separator is provided downstream of the combustor and connected to the combustion gas discharge line, A compressor is provided in the middle of the combustion gas discharge line and supplies the combustion gas to the second membrane separator, A second permeate gas discharge line for discharging the second permeate gas that has permeated through the membrane separation of the second membrane separator, A second non-permeable gas discharge line discharges the second non-permeable gas that is not permeated by the membrane separation of the second membrane separator and supplies it to the first membrane separator, A carbon dioxide separation device equipped with the following features.

2. A first vacuum pump is provided in the middle of the second permeate gas discharge line and supplies the second permeate gas to the second membrane separator, A third membrane separator is provided downstream of the second membrane separator and connected to the second permeate gas discharge line, and includes at least one third membrane separator. A third permeate gas discharge line for discharging the third permeate gas that has permeated through the membrane separation of the third membrane separator, A third non-permeable gas discharge line discharges the third non-permeable gas that is not permeated by the membrane separation of the third membrane separator and supplies it to the combustion gas discharge line, The carbon dioxide separation apparatus according to claim 1, comprising a second vacuum pump installed in the middle of the third permeate gas discharge line.

3. The carbon dioxide separation apparatus according to claim 1, wherein when the carbon monoxide concentration downstream of the combustor is below a predetermined value and the oxygen concentration upstream of the combustor is below a predetermined value, the pressure of the combustion gas supplied to the second membrane separator by the compressor is reduced.

4. The carbon dioxide separation apparatus according to claim 1, wherein when the oxygen concentration upstream of the combustor is above a predetermined value, the compressor increases the pressure of the combustion gas supplied to the second membrane separator.

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