Recovery device

Abstract

To provide an argon recovery device which can be easily operated.MEANS FOR SOLVING THE PROBLEM: A collection device recovers argon from exhaust gas generated from fuel combustion, by utilizing pressure swing adsorption. The device may further comprise a supply device which supplies combustion-supporting gas when fuel is combusted. A ratio of nitrogen in the combustion-supporting gas supplied by the supply device is smaller than a ratio of nitrogen in the air. A ratio of oxygen and a ratio of argon in the combustion-supporting gas may be larger than a ratio of oxygen and a ratio of argon in the air.SELECTED DRAWING: Figure 1

Description

[Technical field]

[0001] The present invention relates to a recovery device for recovering argon from exhaust gas. [Background technology]

[0002] Patent Document 1 discloses a prior art technique in which, in order to reduce the amount of oxygen that interferes with the concentration of argon, oxygen in exhaust gas is removed using a catalyst, and then the argon is concentrated and recovered. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Patent No. 3191113 Summary of the Invention [Problem to be solved by the invention]

[0004] The prior art is complicated because it requires an operation to remove oxygen from the exhaust gas.

[0005] The present invention has been made to solve this problem, and has an object to provide an argon recovery device that can be easily operated. [Means for solving the problem]

[0006] A first aspect for achieving this object is a recovery device that recovers argon by utilizing pressure swing adsorption from exhaust gas containing argon, the exhaust gas being a gas generated by the combustion of a fuel.

[0007] In a second aspect, the combustion assisting gas according to the first aspect is provided with a supply device that supplies a combustion assisting gas during combustion of fuel, and the proportion of nitrogen in the combustion assisting gas is lower than the proportion of nitrogen in air.

[0008] In a third embodiment, in the second embodiment, the ratio of oxygen and the ratio of argon in the combustion supporting gas are greater than the ratio of oxygen and the ratio of argon in air.

[0009] In a fourth aspect, in the second or third aspect, the supply device includes a nitrogen separator that separates nitrogen from air using pressure swing adsorption, and the combustion supporting gas includes gas in which nitrogen has been separated from the air by the nitrogen separator.

[0010] A fifth aspect is the method according to any one of the first to fourth aspects, further comprising a separation device that separates carbon dioxide from the exhaust gas.

[0011] In a sixth embodiment, in any one of the first to fifth embodiments, the adsorbent used in the pressure swing adsorption is a zeolite. Effect of the Invention

[0012] According to the present invention, since the exhaust gas generated by the combustion of fuel contains a small amount of oxygen, argon can be recovered from the exhaust gas by pressure swing adsorption, which simplifies the operation. [Brief description of the drawings]

[0013] [Figure 1] FIG. 2 is a piping diagram of the recovery device in the first embodiment. [Diagram 2] FIG. 11 is a piping diagram of a recovery device in a second embodiment. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0014] Hereinafter, preferred embodiments of the present invention will be described with reference to the accompanying drawings. Fig. 1 is a piping diagram of a recovery device 10 in a first embodiment. The recovery device 10 is a device that recovers argon from the exhaust gas of a combustion device 11 by using pressure swing adsorption.

[0015] The combustion device 11 is a device that burns fuel. Examples of fuel include combustible waste such as household waste and commercial waste, natural gas, oil, coal, coke, charcoal, and firewood, but there are no particular limitations as long as the material can be burned to become a heat source. The fuel emits heat and light in the combustion device 11 and combines with oxygen. The approximate volumetric proportions of substances contained in air are nitrogen 78%, oxygen 21%, and argon 1%. When fuel is burned in the combustion device 11 using oxygen in the air, the proportion of oxygen in the exhaust gas from the combustion device 11 decreases and the proportion of carbon dioxide increases compared to the proportion in the air.

[0016] When argon in air is concentrated by pressure swing adsorption, there is a problem that oxygen is concentrated in roughly proportion to argon because argon and oxygen have similar adsorption characteristics, which interferes with the concentration of argon. Recovery device 10 concentrates argon in the exhaust gas from combustion device 11, which contains little oxygen, by pressure swing adsorption, thereby reducing the adverse effects of oxygen concentration when concentrating and recovering argon.

[0017] The recovery device 10 is equipped with a supply device 12 that supplies a combustion supporting gas to the combustion device 11. The combustion supporting gas is a gas necessary to assist the combustion of fuel, and examples of the combustion supporting gas include air, oxygen, chlorine, fluorine, nitrous oxide, nitric oxide, and nitrogen dioxide. In order to reduce the proportion of nitrogen in the exhaust gas without increasing the components of the exhaust gas from the combustion device 11, the combustion supporting gas is preferably oxygen.

[0018] The supply device 12 includes a nitrogen separation device 13 that separates nitrogen from air using pressure swing adsorption. In this embodiment, the nitrogen separation device 13 is of a PSA type and includes adsorption towers 14, 15 and a pressurizing device 16 that pressurizes air and supplies it to the adsorption towers 14, 15. An adsorbent that adsorbs nitrogen is contained in the adsorption towers 14, 15. Examples of the adsorbent include molecular sieving carbon and zeolite. The pressurizing device 16 is a device that pressurizes the air to set the adsorption towers 14, 15 to an appropriate pressure, and examples of the pressurizing device 16 include a compressor and a blower.

[0019] Three-way valves (3-port valves) 17 and 18 are disposed between the pressurizing device 16 and the adsorption towers 14 and 15, respectively. When the flow path for flowing air from the pressurizing device 16 to the adsorption tower 14 is set in the three-way valve 17, the flow path for flowing gas from the adsorption tower 15 to the exhaust pipe 19 is set in the three-way valve 18. On the other hand, when the flow path for flowing gas from the adsorption tower 14 to the exhaust pipe 19 is set in the three-way valve 17, the flow path for flowing air from the pressurizing device 16 to the adsorption tower 15 is set in the three-way valve 18. This is repeated alternately.

[0020] When air pressurized by the pressurizer 16 enters the adsorption tower 14 through the three-way valve 17, the nitrogen in the air is adsorbed by the adsorbent in the adsorption tower 14, and the separated gas from which nitrogen has been separated (gas with a lower nitrogen partial pressure than air) enters the separated gas pipe 20. A part of the separated gas enters the adsorption tower 15 through the variable throttle valve 21. Because the pressure in the adsorption tower 15 drops to near atmospheric pressure, nitrogen is desorbed from the adsorbent in the adsorption tower 15 and is exhausted to the outside of the system through the three-way valve 18 and exhaust pipe 19. When the flow path settings of the three-way valves 17, 18 are repeatedly switched, adsorption and regeneration of the adsorption towers 14, 15 are alternately performed.

[0021] When the control valve 22 arranged in the separated gas pipe 20 is opened, the separated gas, which has a lower nitrogen concentration than air, is continuously supplied to the combustion device 11 as a combustion supporting gas, which has a higher oxygen concentration than air. The proportion of argon in the separated gas becomes higher than the proportion of argon in the air by the amount of nitrogen removed. By restricting the air entering the combustion device 11 and allowing the oxygen in the combustion supporting gas to be used for combustion in the combustion device 11, the proportion of nitrogen in the exhaust gas from the combustion device 11 decreases, and the proportion of argon in the exhaust gas increases relatively. This increases the efficiency of argon recovery.

[0022] The supply device 12 may be a device that separates nitrogen from air using a cryogenic separation method or a gas separation membrane. However, the nitrogen separation device 13 separates nitrogen from air using pressure swing adsorption, so it can reduce power consumption per unit of nitrogen generation compared to the cryogenic separation method in which air is cooled to liquefy and then distilled to separate nitrogen and oxygen. In addition, the nitrogen separation device 13 has a higher nitrogen separation ability than a gas separation membrane, so it can reduce the proportion of nitrogen in the separated gas (combustion-supporting gas), and therefore the proportion of nitrogen in the exhaust gas from the combustion device 11.

[0023] In the recovery device 10, a removal device 23, an argon separator 24, and a carbon dioxide separator 34 are connected in that order downstream of the combustion device 11. The removal device 23 is a device that removes one or more of impurities contained in the exhaust gas, such as dust, moisture, carbon monoxide, nitrogen oxides (NOx), and sulfur oxides (SOx).

[0024] Examples of the device for removing dust in the removal device 23 include a water washing tower, a Venturi scrubber, an electric dust collector, and a filter. Examples of the removal of moisture and carbon monoxide include a device that uses an adsorbent that selectively adsorbs moisture and carbon monoxide. Examples of the adsorbent include alumina, activated carbon, zeolite, and complexes. Examples of the removal of nitrogen oxides include a wet method using caustic soda or the like, and a dry method using a denitrification catalyst and a reducing agent. Examples of the removal of sulfur oxides include a dry method using a solid absorbent, and a wet method using an aqueous solution absorbent. If the removal device 23 is connected upstream of the separation devices 24, 34, the deterioration of the performance of the separation devices 24, 34 due to impurities can be reduced.

[0025] The separation device 24 is a device that separates and recovers argon from the exhaust gas, and is a PSA type in this embodiment. The separation device 24 includes adsorption towers 25, 26, and a pressurizing device 27 that pressurizes the exhaust gas and supplies it to the adsorption towers 25, 26. An adsorbent made of zeolite that adsorbs argon is contained in the adsorption towers 25, 26. The pressurizing device 27 is a device that pressurizes the exhaust gas to set the adsorption towers 25, 26 to an appropriate pressure, and is exemplified by a compressor or a blower.

[0026] Three-way valves 28, 29 are disposed between the pressurizing device 27 and the adsorption towers 25, 26, respectively. When the flow path for flowing exhaust gas from the pressurizing device 27 to the adsorption tower 25 is set in the three-way valve 28, the flow path for flowing gas from the adsorption tower 26 to the recovery pipe 30 is set in the three-way valve 29. On the other hand, when the flow path for flowing gas from the adsorption tower 25 to the recovery pipe 30 is set in the three-way valve 28, the flow path for flowing exhaust gas from the pressurizing device 27 to the adsorption tower 26 is set in the three-way valve 29. This is repeated alternately.

[0027] When the exhaust gas pressurized by the pressurizer 27 enters the adsorption tower 25 through the three-way valve 28, argon in the exhaust gas is adsorbed by the adsorbent in the adsorption tower 25, and the off-gas from which argon has been separated enters the off-gas pipe 31. A part of the off-gas enters the adsorption tower 26 through a variable throttle valve 32. Because the pressure in the adsorption tower 26 drops to near atmospheric pressure, argon is desorbed from the adsorbent in the adsorption tower 26 and is recovered in a tank 33 through the three-way valve 29 and recovery pipe 30. When the flow path settings of the three-way valves 28, 29 are repeatedly switched, adsorption and regeneration of the adsorption towers 25, 26 are alternately performed.

[0028] The separation device 34 is a device that separates and recovers carbon dioxide from the off-gas, and is a PSA type in this embodiment. The separation device 34 includes adsorption towers 35, 36, and a pressurizing device 37 that pressurizes the off-gas and supplies it to the adsorption towers 35, 36. An adsorbent that adsorbs carbon dioxide is contained in the adsorption towers 35, 36. Examples of the adsorbent include molecular sieving carbon and zeolite. The pressurizing device 37 is a device that pressurizes the off-gas to set the adsorption towers 35, 36 to an appropriate pressure, and examples of the pressurizing device 37 include a compressor and a blower.

[0029] Three-way valves 38, 39 are disposed between the pressurizing device 37 and the adsorption towers 35, 36, respectively. When the flow path for flowing the off-gas from the pressurizing device 37 to the adsorption tower 35 is set in the three-way valve 38, the flow path for flowing the gas from the adsorption tower 36 to the recovery pipe 40 is set in the three-way valve 39. On the other hand, when the flow path for flowing the gas from the adsorption tower 35 to the recovery pipe 40 is set in the three-way valve 38, the flow path for flowing the off-gas from the pressurizing device 37 to the adsorption tower 36 is set in the three-way valve 39. This is repeated alternately.

[0030] When the off-gas pressurized by the pressurizer 37 enters the adsorption tower 35 through the three-way valve 38, the carbon dioxide in the off-gas is adsorbed by the adsorbent in the adsorption tower 35, and the gas from which carbon dioxide has been separated is discharged to the outside of the system through an exhaust pipe 41. A part of the gas from which carbon dioxide has been separated enters the adsorption tower 36 through a variable throttle valve 42. Because the pressure in the adsorption tower 36 drops to near atmospheric pressure, the carbon dioxide is desorbed from the adsorbent in the adsorption tower 36 and flows through the three-way valve 39 into the recovery pipe 40. When the flow path settings of the three-way valves 38, 39 are repeatedly switched, adsorption and regeneration of the adsorption towers 35, 36 are alternately performed.

[0031] A tank 43 is connected to the recovery pipe 40. Gas with a high carbon dioxide concentration is stored in the tank 43. There is no restriction on how the carbon dioxide stored in the tank 43 can be used. One example is to react the carbon dioxide stored in the tank 43 with hydrogen to synthesize organic compounds such as methane and methanol.

[0032] A second embodiment will be described with reference to Fig. 2. In the first embodiment, a case where argon is recovered using an adsorbent that selectively adsorbs argon is described. In contrast, in the second embodiment, a case where argon is recovered using an adsorbent that does not selectively adsorb argon is described. In the second embodiment, the same parts as those described in the first embodiment are denoted by the same reference numerals, and the following description will be omitted.

[0033] 2 is a piping diagram of a recovery device 50 in the second embodiment. The recovery device 50 is equipped with a supply device 51 that supplies a combustion supporting gas to the combustion device 11. The supply device 51 is of a PSA type and includes adsorption towers 52, 53 and a pressurizing device 16 that pressurizes air and supplies it to the adsorption towers 52, 53. An adsorbent that adsorbs oxygen is accommodated in the adsorption towers 52, 53. An example of the adsorbent is zeolite.

[0034] When air pressurized by the pressurizer 16 enters the adsorption tower 52 through the three-way valve 17, the oxygen in the air is adsorbed by the adsorbent in the adsorption tower 52, and the off-gas from which the oxygen has been separated (gas with a lower oxygen partial pressure than air) is discharged to the outside of the system through the exhaust pipe 54. A part of the off-gas enters the adsorption tower 53 through the variable throttle valve 21. Because the pressure in the adsorption tower 53 drops to near atmospheric pressure, oxygen is desorbed from the adsorbent in the adsorption tower 53 and enters the recovery pipe 55 through the three-way valve 18. When the flow path settings of the three-way valves 17 and 18 are repeatedly switched, adsorption and regeneration of the adsorption towers 52 and 53 are alternately performed.

[0035] When the control valve 56 arranged in the recovery pipe 55 is opened, the combustion supporting gas, which has a higher oxygen concentration and a lower nitrogen concentration than air, is continuously supplied to the combustion device 11. The proportion of argon in the combustion supporting gas is greater than the proportion of argon in air to the extent that the oxygen is concentrated and the nitrogen is removed. By restricting the air entering the combustion device 11 and allowing the oxygen in the combustion supporting gas to be used for combustion in the combustion device 11, the proportion of nitrogen in the exhaust gas from the combustion device 11 decreases, and the proportion of argon in the exhaust gas increases relatively. This increases the efficiency of argon recovery.

[0036] Supply device 51 may separate oxygen using cryogenic separation, but because supply device 51 separates oxygen from air using pressure swing adsorption, it can consume less power per unit of oxygen produced than cryogenic separation.

[0037] In the recovery device 50, a removal device 23, a carbon dioxide separator 34, and a nitrogen separator 57 are connected in this order downstream of the combustion device 11. The separator 34 is a device that separates and recovers carbon dioxide from the exhaust gas, and is of a PSA type in this embodiment. The downstream end of the recovery pipe 40 is connected to a tank 43.

[0038] The separated gas from which carbon dioxide has been separated from the exhaust gas by the separator 34 is supplied from the exhaust pipe 41 to the separator 57. The separator 57 is a device that separates nitrogen from the separated gas and recovers argon, and is a PSA type in this embodiment. The separator 57 includes adsorption towers 58, 59 and a pressurizing device 60 that pressurizes the separated gas and supplies it to the adsorption towers 58, 59. An adsorbent that adsorbs nitrogen is contained in the adsorption towers 58, 59. Examples of the adsorbent include molecular sieving carbon and zeolite. The pressurizing device 60 is a device that pressurizes the separated gas to set the adsorption towers 58, 59 to an appropriate pressure, and examples of the pressurizing device 60 include a compressor and a blower.

[0039] Three-way valves 61, 62 are disposed between the pressurizing device 60 and the adsorption towers 58, 59, respectively. When the flow path for flowing exhaust gas from the pressurizing device 60 to the adsorption tower 58 is set in the three-way valve 61, the flow path for flowing gas from the adsorption tower 59 to the exhaust pipe 63 is set in the three-way valve 62. On the other hand, when the flow path for flowing gas from the adsorption tower 58 to the exhaust pipe 63 is set in the three-way valve 61, the flow path for flowing separated gas from the pressurizing device 60 to the adsorption tower 59 is set in the three-way valve 62. This is repeated alternately.

[0040] When the separated gas pressurized by the pressurizing device 60 enters the adsorption tower 58 through the three-way valve 61, the nitrogen in the separated gas is adsorbed by the adsorbent in the adsorption tower 58. The gas from which nitrogen has been separated in the adsorption tower 58 and has a high argon concentration enters a tank 65 through a recovery pipe 64. A part of the gas enters the adsorption tower 59 through a variable throttle valve 66. Since the pressure in the adsorption tower 59 drops to near atmospheric pressure, nitrogen is desorbed from the adsorbent in the adsorption tower 59 and is discharged outside the system through the three-way valve 62 and exhaust pipe 63. When the flow path settings of the three-way valves 61, 62 are repeatedly switched, adsorption and regeneration are alternately performed in the adsorption towers 58, 59.

[0041] The present invention has been described above based on an embodiment, but the present invention is in no way limited to the above embodiment, and it can be easily inferred that various improvements and modifications are possible within the scope of the present invention without departing from the spirit of the present invention.

[0042] For example, the piping system of the recovery device 10 is an example and can be set as appropriate. In the embodiment, the nitrogen separation device 13, the separation devices 24, 34, 57, and the supply device 51 each include two adsorption towers, but this is not necessarily limited to this. The number of adsorption towers is set to one or more as appropriate.

[0043] In the first embodiment, the carbon dioxide separator 34 is connected downstream of the argon separator 24, but this is not necessarily limited to this. It is of course possible to switch the positions of the separators 24, 34 and connect the argon separator 24 downstream of the carbon dioxide separator 34.

[0044] In the second embodiment, the nitrogen separator 57 is connected downstream of the carbon dioxide separator 34, but this is not necessarily limited to this. It is of course possible to connect the carbon dioxide separator 34 downstream of the nitrogen separator 57 by interchanging the positions of the separators 34 and 57.

[0045] In the embodiment, the nitrogen separation device 13, the separators 24, 34, 57, and the supply device 51 are PSA type devices, but the present invention is not limited to this. It is of course possible to replace any one or more of the nitrogen separation device 13, the separators 24, 34, 57, and the supply device 51 with a VSA type or PVSA type device in which a vacuum pump is disposed downstream of the pressurizing device 16, 27, 37, 60 and the pressure is reduced by the vacuum pump during desorption and regeneration of the adsorbent. Since the operating pressure of the VSA type or PVSA type device is close to atmospheric pressure, power consumption can be reduced compared to the PSA type device. [Explanation of symbols]

[0046] 10,50 Recovery device 12,51 Feeding device 13 Nitrogen Separator 34 Separation device

Claims

1. A recovery apparatus for recovering argon from an exhaust gas containing argon by pressure swing adsorption, comprising: A recovery device for the exhaust gas, the exhaust gas being gas generated by the combustion of fuel.

2. A supply device is provided for supplying a combustion supporting gas during combustion of the fuel, 2. The recovery apparatus according to claim 1, wherein the proportion of nitrogen in said combustion supporting gas is less than the proportion of nitrogen in air.

3. 3. The recovery apparatus according to claim 2, wherein the ratio of oxygen and the ratio of argon in said combustion supporting gas are greater than the ratio of oxygen and the ratio of argon in air.

4. the supply system includes a nitrogen separator that utilizes pressure swing adsorption to separate nitrogen from air; 4. The recovery system according to claim 2, wherein the combustion supporting gas includes a gas obtained by separating nitrogen from air by the nitrogen separator.

5. The recovery system according to claim 1 , further comprising a separation device that separates carbon dioxide from the exhaust gas.

6. 4. The recovery system of claim 1, wherein the adsorbent used in the pressure swing adsorption is a zeolite.

Images