JP2025000158A - Recovery device - Google Patents

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

The present invention relates to a recovery device that recovers argon from exhaust gas.

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 the exhaust gas is removed using a catalyst, and then the argon is concentrated and recovered.

Patent No. 3191113

Prior art technology is complicated because it requires operations to remove oxygen from exhaust gas.

The present invention was made to solve this problem, and aims to provide an argon recovery device that is easy to operate.

The first aspect to achieve this objective is a recovery device that uses pressure swing adsorption to recover argon from exhaust gas containing argon, the exhaust gas being gas generated by the combustion of fuel.

In the second aspect, the first aspect is provided with a supply device that supplies a combustion-supporting gas when the fuel is burned, and the proportion of nitrogen in the combustion-supporting gas is less than the proportion of nitrogen in air.

In the third embodiment, the proportion of oxygen and the proportion of argon in the combustion supporting gas are greater than the proportion of oxygen and the proportion of argon in air.

In the 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 air by the nitrogen separator.

In a fifth aspect, in any one of the first to fourth aspects, a separation device is further provided for separating carbon dioxide from the exhaust gas.

In a sixth aspect, in any one of the first to fifth aspects, the adsorbent used in the pressure swing adsorption is a zeolite.

According to the present invention, since the exhaust gas generated by fuel combustion contains a small amount of oxygen, argon can be recovered from the exhaust gas by using pressure swing adsorption. This simplifies the operation.

FIG. 2 is a piping diagram of the recovery device according to the first embodiment. FIG. 11 is a piping diagram of a recovery device according to a second embodiment.

The following describes preferred embodiments of the present invention with reference to the accompanying drawings. Figure 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 using pressure swing adsorption.

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 78% nitrogen, 21% oxygen, and 1% argon. When the combustion device 11 burns fuel using the 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.

When argon in the 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. The recovery device 10 concentrates argon in the exhaust gas from the combustion device 11, which contains little oxygen, by pressure swing adsorption, thereby reducing the adverse effects of oxygen concentration when concentrating and recovering argon.

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, oxygen is preferable as the combustion supporting gas.

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 a PSA type device, 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.

Three-way valves (three-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.

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 the 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, the nitrogen is desorbed from the adsorbent in the adsorption tower 15 and is exhausted outside the system through the three-way valve 18 and exhaust pipe 19. When the flow path settings of the three-way valves 17 and 18 are repeatedly switched, adsorption and regeneration of the adsorption towers 14 and 15 are alternately performed.

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 to the extent that nitrogen has been 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.

The supply device 12 may be a device that separates nitrogen from the air using a cryogenic separation method or a gas separation membrane. However, the nitrogen separation device 13 separates nitrogen from the air using pressure swing adsorption, so it can reduce the power consumption per unit of nitrogen generated compared to the cryogenic separation method, in which air is cooled and liquefied, 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.

In the recovery system 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 the impurities contained in the exhaust gas, such as dust, moisture, carbon monoxide, nitrogen oxides (NOx), and sulfur oxides (SOx).

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 those using 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, etc., 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.

The separation device 24 is a device that separates and recovers argon from the exhaust gas, and in this embodiment is a PSA type. The separation device 24 is equipped with adsorption towers 25, 26 and a pressurizing device 27 that pressurizes the exhaust gas and supplies it to the adsorption towers 25, 26. The adsorption towers 25, 26 contain an adsorbent made of zeolite that adsorbs argon. The pressurizing device 27 is a device that pressurizes the exhaust gas to set the adsorption towers 25, 26 to an appropriate pressure, and examples of this include a compressor and a blower.

Three-way valves 28, 29 are arranged 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.

When the exhaust gas pressurized by the pressurizing device 27 enters the adsorption tower 25 through the three-way valve 28, the argon in the exhaust gas is adsorbed by the adsorbent in the adsorption tower 25, and the off-gas from which the argon has been separated enters the off-gas pipe 31. A portion of the off-gas enters the adsorption tower 26 through the variable throttle valve 32. As 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 the tank 33 through the three-way valve 29 and recovery pipe 30. When the flow path settings of the three-way valves 28 and 29 are repeatedly switched, adsorption and regeneration of the adsorption towers 25 and 26 are alternated.

The separation device 34 is a device that separates and recovers carbon dioxide from the off-gas, and in this embodiment is a PSA system. The separation device 34 is equipped with 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.

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

When the off-gas pressurized by the pressurizing device 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 the carbon dioxide has been separated is discharged to the outside of the system through the exhaust pipe 41. A part of the gas from which the carbon dioxide has been separated enters the adsorption tower 36 through the 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 and 39 are repeatedly switched, the adsorption and regeneration of the adsorption towers 35 and 36 are alternated.

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

The second embodiment will be described with reference to FIG. 2. In the first embodiment, the case where argon is recovered using an adsorbent that selectively adsorbs argon is described. In contrast, in the second embodiment, the 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.

Figure 2 is a piping diagram of the recovery device 50 in the second embodiment. The recovery device 50 is equipped with a supply device 51 that supplies combustion-supporting gas to the combustion device 11. The supply device 51 is of the PSA type and is equipped with 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 stored in the adsorption towers 52, 53. An example of the adsorbent is zeolite.

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 passes through the variable throttle valve 21 and enters the adsorption tower 53. 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 alternated.

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.

The supply device 51 may separate oxygen using cryogenic separation. However, because the supply device 51 separates oxygen from air using pressure swing adsorption, the power consumption per unit amount of oxygen generated can be reduced compared to the cryogenic separation method.

In the recovery system 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 in this embodiment, is a PSA type. The downstream end of the recovery pipe 40 is connected to a tank 43.

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 in this embodiment is a PSA type. The separator 57 is equipped with adsorption towers 58, 59 and a pressurizing device 60 that pressurizes the separated gas and supplies it to the adsorption towers 58, 59. The adsorption towers 58, 59 contain an adsorbent that adsorbs nitrogen. 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.

Three-way valves 61, 62 are arranged 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 to the three-way valve 61, the flow path for flowing gas from the adsorption tower 59 to the exhaust pipe 63 is set to 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 to the three-way valve 61, the flow path for flowing separated gas from the pressurizing device 60 to the adsorption tower 59 is set to the three-way valve 62. This is repeated alternately.

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 with a high argon concentration from which nitrogen is separated in the adsorption tower 58 enters the tank 65 through the recovery pipe 64. A portion of the gas enters the adsorption tower 59 through the variable throttle valve 66. Since the pressure in the adsorption tower 59 drops to near atmospheric pressure, the nitrogen is desorbed from the adsorbent in the adsorption tower 59 and is discharged outside the system through the three-way valve 62 and the exhaust pipe 63. When the flow path settings of the three-way valves 61 and 62 are repeatedly switched, the adsorption towers 58 and 59 alternate between adsorption and regeneration.

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

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 are each provided with two adsorption towers, but this is not necessarily limited to this. The number of adsorption towers can be set to one or more as appropriate.

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 and 34 and connect the argon separator 24 downstream of the carbon dioxide separator 34.

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 switch the positions of the separators 34 and 57 and connect the carbon dioxide separator 34 downstream of the nitrogen separator 57.

In the embodiment, the nitrogen separation device 13, the separation devices 24, 34, 57, and the supply device 51 are PSA type devices, but this is not limited to this. It is of course possible to replace any one or more of the nitrogen separation device 13, the separation devices 24, 34, 57, and the supply device 51 with a VSA type or PVSA type device in which a vacuum pump is placed downstream of the pressure 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.

10, 50 Recovery device 12, 51 Supply device 13 Nitrogen separation device 34 Separation device

Claims (6)

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. 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. The recovery device according to claim 2, wherein 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. 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. The recovery device according to any one of claims 1 to 3, further comprising a separation device that separates carbon dioxide from the exhaust gas. The recovery device according to any one of claims 1 to 3, wherein the adsorbent used in the pressure swing adsorption is zeolite.

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