JP2006083311A - Apparatus for refining sewage gas and method for refining the same gas - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an apparatus and a method for refining sewage gas in which removal of a siloxane compound and methane concentration can stably be carried out for a long period from a sewage gas. <P>SOLUTION: In the apparatus for refining the sewage gas containing a siloxane compound, the apparatus has a siloxane compound-removing part 5 and a methane concentration part 7 on the downstream side of the siloxane compound-removing part 5. The methane concentration part 7 is equipped with a pressure swing absorption apparatus having a plurality of packed layers 8 in which a carbon dioxide absorbent is each packed and having regenerating means 10, 11 and 12 for alternatively regenerating the packed layers 8, and the siloxane compound-removing part 5 can be equipped with an absorption apparatus having a packed layer 6 in which a siloxane compound absorbing agent is packed or a pressure swing or heat swing absorption apparatus having a plurality of the packed layers and having a regenerating means for alternatively regenerating these packed layers, and a gas generated by regenerating treatment of the methane concentration part can be used as a purge gas for regenerating the siloxane absorbent. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a digestion gas purification apparatus and method, and more specifically, a siloxane compound from digestion gas containing a siloxane compound generated when anaerobic fermentation of organic waste such as garbage and sewage sludge is performed. The present invention relates to a method and an apparatus for purifying a gas having high utility value as a fuel having a methane concentration equivalent to or close to natural gas while removing carbon dioxide and concentrating methane.

Digestion gas generated by anaerobic fermentation of organic waste such as garbage and sewage sludge contains methane, which is a combustible component, so its utility value as a fuel has been reviewed in recent years. Development of methods for obtaining power by supplying power to power generation facilities such as engines, gas turbines, and fuel cells is being actively promoted.
When using digestion gas as a gas engine or boiler fuel, it is not impossible to use the gas after desulfurization as it is. However, carbon dioxide contained in the digestion gas is separated and removed to obtain high-concentration methane gas. It is desirable in terms of handling such as energy efficiency and storage / transport.

  As a method of concentrating methane by separating and removing carbon dioxide in digestion gas, wet adsorption method using special absorption liquid such as water, alkaline cleaning liquid, ethanolamine aqueous solution, activated carbon, zeolite, metal complex etc. are adsorbed The dry adsorption method used as an agent has been performed. Digestion gas contains a large amount of carbon dioxide (about 40%), so many of the above carbon dioxide removal methods regenerate the carbon dioxide absorbent and adsorbent at the current position. The pressure swing adsorption method that continuously separates and removes the adsorbent while regenerating the adsorbent at the current position using the pressure difference, and the thermal swing adsorption method that regenerates at the current position using heat instead of pressure. This is a well-known method. Also, in the case of the wet absorption method, when there are restrictions on the amount of water used or the amount of drainage, a method of regenerating the liquid after carbon dioxide absorption using steam or the like may be employed.

On the other hand, it is clear that such digestive gas contains trace components that adversely affect the power generation facilities described above, and a countermeasure is taken mainly by Western countries where digestion gas power generation technology is ahead. Is being considered. Among such trace components, volatile organosilicon compounds are particularly attracting attention. In sewage sludge digestion gas, siloxane compounds derived from organosilicon contained in shampoos and rinses are several to several tens mg. It is known to be contained at a concentration of / m ³ .
The siloxane compound is a silicon compound having a siloxane bond (—Si—O—) as a basic skeleton, and is a siloxane bond in which the siloxane bonds are linearly bonded or cyclically bonded. Among such siloxane compounds, sewage sludge digestion gas includes octamethylcyclotetrasiloxane in which four unit structures of siloxane bonds are bonded in a ring, or decamethylcyclohexane in which five unit structures of siloxane bonds are bonded in a ring. Pentasiloxane is contained at a relatively high concentration.

When digestion gas containing a volatile organosilicon compound such as a siloxane compound is used as a fuel, for example, when a gas engine is driven to generate electric power, the siloxane compound changes into solid silica (SiO ₂ ) by combustion in the gas engine. This solid silica adheres to the spark plug of the engine and causes ignition failure, premature wear of cylinder liners and pistons, and damage to the gas engine due to adhesion to the intake valve, exhaust valve, and engine combustion chamber head as a whole. Cause it. Similar obstacles are believed to occur in other internal combustion engines such as gas turbines.
In order to achieve such long-term stable operation of an internal combustion engine such as a gas engine, various methods for removing a cyclosan compound have been proposed. For example, a method of adsorbing and removing with a porous agent such as activated carbon (Pete H. Air and Waste Management Association, Annual Conference: St Louis, MO, 1999, F-99-330, etc.), a wet absorption method using a solvent, etc. The digestion gas is cooled to about −30 ° C., condensed and separated (German Patent Publication DE 19810993).

As described above, the method of concentrating methane by separating carbon dioxide from the digestion gas, and the method and apparatus for removing the siloxane compound from the digestion gas and purifying them are well known and have been put into practical use in many cases. .
Methane concentration and siloxane removal can be separated and removed by a similar principle such as wet method using an absorbent and dry method using an adsorbent, but carbon dioxide and siloxane are originally used as digestive gases. There is a problem that it is difficult to remove them with the same removal medium because the contained amounts vary greatly and the physical properties differ greatly.
Air and Waste Management Association, Annual Conference: St Louis, MO, 1999, F-99-330 German Patent Publication DE19810993

  An object of the present invention is to solve the above-mentioned problems of the prior art and to provide a digestion gas purification apparatus and method capable of stably removing siloxane compounds from digestion gas and concentrating methane for a long period of time. To do.

In order to solve the above-mentioned problems, the present invention is a digestion gas purification apparatus containing a siloxane compound, characterized in that the apparatus has a siloxane compound removal unit and a methane concentration unit downstream thereof. This is an apparatus for purifying digestion gas.
In the digestion gas purification apparatus, the methane concentrating unit includes a plurality of packed beds filled with a carbon dioxide adsorbent, and includes a pressure swing adsorbing device having a regenerating unit for alternately regenerating the packed layers, The siloxane compound removing unit includes an adsorption device having a packed layer filled with a siloxane compound adsorbent, or has a plurality of packed layers filled with the adsorbent, and alternately regenerates the packed layers. The pressure swing adsorption device and / or the thermal swing adsorption device having the above regeneration means can be provided.

  Further, in the present invention, a purification apparatus for digestion gas containing a siloxane compound, the apparatus has a plurality of packed layers filled with a siloxane compound adsorbent for removing the siloxane compound installed on the upstream side, A plurality of pressure swing adsorption devices and / or thermal swing adsorption devices having regeneration means for alternately regenerating the packed bed, and a plurality of carbon dioxide adsorbents for concentrating methane in digestion gas installed on the downstream side A pressure swing adsorption device having a packed bed and having a regeneration means for alternately regenerating the packed bed, and siloxane adsorption of exhaust gas mainly composed of carbon dioxide generated during regeneration of the carbon dioxide adsorbent Or a digestion gas purification apparatus comprising a purge pipe for use as a purge gas for agent regeneration, or a digestion gas containing a siloxane compound A purifier packed with a carbon dioxide adsorbent for concentrating methane in digestion gas and a siloxane adsorbent for removing a siloxane compound provided upstream of the packed bed A pressure swing adsorption device having a plurality of packed towers packed in the same tower, and having a regeneration means for alternately regenerating the adsorbent in the packed tower for each packed tower. The digester gas purifier is characterized.

Furthermore, in the present invention, in the purification method for digestion gas containing the siloxane compound, the digestion gas purification method is characterized in that methane concentration is performed after removing the siloxane compound from the digestion gas in advance. Is.
In the digestion gas purification method, the methane concentration is performed by adsorbing and removing carbon dioxide by a pressure swing adsorption method using an adsorbent, and the siloxane compound is removed by adsorption removal using an adsorbent, or the adsorbent. Can be performed by a pressure swing adsorption method and / or a thermal swing adsorption method.
Further, in the present invention, in the method for purifying a digestion gas containing a siloxane compound, after removing the siloxane compound from the digestion gas in advance by using a pressure swing adsorption method and / or a thermal swing adsorption method using an adsorbent, Adsorbent that adsorbs siloxane compound with exhaust gas mainly composed of carbon dioxide generated during regeneration of adsorbent for methane concentration while performing methane concentration to remove carbon dioxide by pressure swing adsorption method using adsorbent This is a digestion gas purification method characterized in that it is used as a purge gas for regeneration.

  By using the digestion gas purification apparatus and method of the present invention, a purified gas having a high methane concentration and containing no siloxane as an impurity, that is, having a high utility value equivalent to or close to that of natural gas, can be easily obtained from the digestion gas. It can be obtained efficiently.

  Embodiments of the digestion gas purification apparatus of the present invention will be described below. That is, the inventors have conducted various investigations and studies on the energy utilization of digestion gas. As a result, in particular, when applying a micro gas turbine or a fuel cell as a digestion gas power generation facility, the inventor is a trace impurity in digestion gas. It has been found that a gas that has been subjected to both siloxane removal and carbon dioxide removal for methane concentration is indispensable, and siloxane removal equipment that has been attracting attention in recent years is difficult to remove carbon dioxide. As a result of various researches, it was clarified that it is difficult to remove siloxane with known carbon dioxide removal equipment, so we came up with a digestion gas purification equipment consisting of a siloxane removal section and a methane concentration section. Is.

  Furthermore, as a result of various investigations and researches, we have found that siloxane compounds in addition to sulfur compounds such as hydrogen sulfide are well known as inhibitors for the carbon dioxide separation and removal agent in the methane concentration section. Based on the above, it was verified that the methane concentration was performed stably for a long period of time by removing the siloxane compound in advance, instead of simply combining these removal devices, and the present invention was achieved. Furthermore, paying attention to the exhaust gas mainly composed of carbon dioxide discharged from the methane enrichment part, it can be used as a regeneration gas for the upstream siloxane adsorbent, and the siloxane removal part and the methane enrichment part are the same in the series direction It has been found that the exhaust gas can be easily and effectively used as a regenerative gas by mounting it in the purification apparatus.

In the present invention, the digestion gas is obtained by anaerobic fermentation of organic waste produced in a sewage treatment facility, sludge regeneration treatment center, beer / soft drink manufacturing factory, livestock breeding ground, etc. It contains carbon dioxide and a siloxane compound as gas components other than methane.
Various methods for removing siloxane and concentrating methane are known and can be carried out by combining various methods such as a wet method and a dry method. , Waste liquid treatment after use is necessary, and it is difficult to recycle and reuse the absorbent except for some absorbents. Some power generation facilities dislike the effects of moisture in the gas. Because there are some things, it is necessary to dehumidify the purified gas again, and there are various restrictions and issues such as generally increasing the size of the equipment compared to the dry method. Not applicable. In the present invention, in particular, as a result of repeated studies based on such problems, a method of performing siloxane compound removal and methane concentration by a dry adsorption method is adopted as a more preferable method.

As the adsorption device for methane concentration, the concentration of carbon dioxide in the digestion gas is as high as several tens of percent, so it is practical to use a pressure swing method or heat swing method device of the current position regeneration type. In particular, the pressure swing method is advantageous and has already been proven. The carbon dioxide adsorbent used here may be one that has been generally used conventionally, and for example, molecular sieving carbon or an organometallic complex can be used.
On the other hand, as an adsorption device for removing siloxane, since the concentration of siloxane in the digestion gas is as low as several to several tens mg / m ³ , it is always necessary to be an in-situ regeneration type device if the amount of adsorption is large. However, by adopting the current position regenerative type, it is possible to omit complicated adsorbent replacement work and to make the apparatus itself more compact. Examples of the adsorbent include activated carbon, silica gel, zeolite, and other molecular adsorbents.
In addition, there is no limitation on the adsorbent in the case of a current position regeneration type apparatus, but it is desirable to select the adsorbent in consideration of not only the adsorption performance but also the desorption performance.

When both the dry adsorption device for methane concentration and the dry adsorption device for siloxane removal are configured as in-situ regeneration type devices, the exhaust gas mainly composed of carbon dioxide discharged from the methane concentration device is treated with siloxane. It may be used as a purge gas for regeneration of the removal adsorbent. In the regeneration of the adsorbent when a combustible gas such as digestion gas is purified by the adsorption method, a gas containing oxygen such as air cannot be used as a purge gas for safety reasons. Normally, it is necessary to separately use an inert gas such as nitrogen as the purge gas. By adopting the above-described form, it is possible to effectively use the exhaust gas mainly composed of carbon dioxide generated from the inside of the apparatus without using this. it can.
What should be noted when adopting the dry adsorption method is the influence of hydrogen sulfide and moisture contained in the digestion gas, and it has been found that these components have a considerable influence on the apparatus and method of the present invention. ing. Even if conventional methane is burned as surplus gas in general digestion gas generation facilities, secondary pollution such as the generation of sulfurous acid gas will occur if high-concentration hydrogen sulfide is contained in the digestion gas. Therefore, after removing hydrogen sulfide in advance using a desulfurization agent or wet absorption method, etc., it is temporarily stored in a gas holder or the like, so if methane gas after desulfurization is used as a purge gas for siloxane removal adsorbent regeneration good.

On the other hand, digestion gas contains a large amount of moisture close to saturation, but unless there are special circumstances, dehumidification of the gas is often not performed. Therefore, it is preferable that the water removal be performed together with the removal of the siloxane compound and the concentration of methane. Examples of the water removal method include an adsorption method using an adsorbent such as silica gel and zeolite, and a mechanical water removal method capable of varying the pressure and temperature.
As described above, the high-concentration methane-containing gas from which siloxane has been removed can be efficiently used as a fuel by various methods. For example, not only is it possible to stably drive an internal combustion engine such as a gas engine or a gas turbine over a long period of time to obtain heat and electricity, but there are few components other than methane, which is the main component, It can be stored efficiently. The advantage of storage is advantageous in various applications, for example, when it is used as fuel for automobiles, and the present invention is very important for efficient use of digestion gas.

Hereinafter, the present invention will be described in detail with reference to the drawings.
FIG. 1 is a flow configuration diagram showing an example of the configuration of the apparatus of the present invention, which includes a siloxane compound removing unit 5 by a dry adsorption method and a pressure swing type methane concentrating unit 7.
The digestion gas 1 after desulfurization and dehumidification is introduced into the siloxane compound removal unit 5 and then into the methane concentration unit 7 to obtain a purified gas 2. In addition to the gas pipe 9, a gas purge pipe 10 and a vacuum pump 12 are connected to the methane concentrating unit 7, and a switching valve for switching the gas ventilation between the gas pipe 9 and the gas purge pipe 10. 11, 11 ′. By the switching valves 11 and 11 ′, gas purification and regeneration of the packed bed 8 filled with the carbon dioxide adsorbent by the pressure reducing action of the vacuum pump 12 are alternately performed. In the regeneration process of the adsorbent, the exhaust gas 3 mainly composed of carbon dioxide desorbed from the packed bed 8 filled with the carbon dioxide adsorbent is discharged from the system by the vacuum pump 12.

FIG. 2 is a flow configuration diagram showing a case of a thermal swing method using a purge gas in which the siloxane compound removing unit 5 is heated and a methane concentrating unit 7 of a pressure swing method in the apparatus of the present invention.
The siloxane compound removing unit 5 has a packed layer 6 filled with a siloxane adsorbent, and the methane concentrating unit 7 has a packed layer 8 filled with a carbon dioxide adsorbent. In addition to the gas pipe 9, a gas purge pipe 10 and a vacuum pump 12 are connected to the methane concentrating unit 7, and switching valves 11 and 11 ′ installed in the respective gas pipes are switched. Gas purification and regeneration of the packed bed 8 filled with the carbon dioxide adsorbent by the pressure reducing action of the vacuum pump 12 are alternately performed. On the other hand, in addition to the gas pipe 9, the siloxane compound removing section 5 is also provided with a gas purge pipe 14 and a heater 13 for heating the purge gas, and switches the switching valves 15 and 15 'installed in the respective gas pipes. As a result, purification of the gas and regeneration of the packed bed 6 filled with the siloxane adsorbent by the action of the heated purge gas 14 are alternately performed.

  FIG. 3 is a flow configuration diagram of another example of the configuration of the apparatus of the present invention, showing a case where the siloxane compound removing unit 5 is a thermal swing method using a heated purge gas and the methane concentrating unit 7 is a pressure swing method. . The siloxane compound removing section 5 has a packed bed 6 filled with a siloxane adsorbent, and the methane concentrating section 7 has a packed bed 8 filled with a carbon dioxide adsorbent. In addition to the gas pipe 9, a gas purge pipe 10 and a vacuum pump 12 are connected to the methane concentrating unit 7. The gas pipe 9 and the gas purge pipe 10 are switched to switch the gas flow. Valves 11 and 11 'are provided. By the switching valves 11 and 11 ′, gas purification and regeneration of the packed bed 8 filled with the carbon dioxide adsorbent by the pressure reducing action of the vacuum pump 12 are alternately performed. The carbon dioxide desorbed from the packed bed 8 filled with the carbon dioxide adsorbent by the vacuum pump 12 becomes the exhaust gas 3.

  On the other hand, in addition to the gas pipe 9, the siloxane compound removing section 5 is provided with a gas purge pipe 14 for using the gas exhausted from the methane concentration section 7 as a purge gas and a heater 13 for heating the purge gas. By switching the switching valves 15 and 15 'installed in the respective gas pipes, the purification of the gas and the regeneration of the packed bed 6 filled with the siloxane adsorbent by the gas purge are alternately performed. In this apparatus, the exhaust gas 3 mainly composed of carbon dioxide generated when regenerating the packed bed 8 filled with the carbon dioxide adsorbent of the methane concentrating unit 7 is used as the packed bed 6 filled with the siloxane adsorbent. Since it can be used as a purge gas for regeneration, it is possible to save the trouble and cost of separately preparing and using a purge gas that does not contain oxygen, which is a combustible component or a combustion-supporting component.

  FIG. 4 is a flow configuration diagram of a purification apparatus having a structure in which one of the purification apparatuses is provided with both the siloxane removal unit 5 and the methane concentration unit 7. In this method, when the packed bed 8 filled with the carbon dioxide adsorbent is regenerated, the exhaust gas mainly composed of carbon dioxide desorbed from the packed bed 8 filled with the carbon dioxide adsorbent is used as it is as the siloxane adsorbent. Since it flows as a purge gas for regeneration of the siloxane adsorbent toward the packed bed 6 filled, there is no need to provide a separate complicated purge pipe, etc. Can be played at the same time.

Example 1
Experiments were performed using an experimental apparatus having the structure shown in FIG.
Methane 55%, 45% carbon dioxide, octamethylcyclotetrasiloxane 4.5 mg / ^{m 3,} intended for sewage sludge digestion gas after desulfurization and dehumidification containing decamethylcyclopentasiloxane 42 mg / ^{m 3.} The experimental conditions are as follows.
(1) Siloxane removal part Adsorbent type: Activated carbon for gas treatment Superficial velocity SV: 360 hr ⁻¹
(2) Methane enrichment part Type of adsorbent: Molecular sieve carbon with a pore size of 5 mm Superficial velocity SV: 300 hr ⁻¹
Regeneration method: Pressure swing adsorption method (reduced pressure regeneration, switching time 5 minutes)
The composition of the purified gas, methane 91%, 9% carbon dioxide, less octamethylcyclotetrasiloxane 0.1 mg / ^{m 3,} or less decamethylcyclopentasiloxane 0.1 mg / ^{m 3,} with stable processing over a long period of time there were.

Comparative Example 1
The experiment was performed under the same conditions as in Example 1 except that the operation was performed without passing through the siloxane removal section.
The composition of the operation beginning of the purified gas, methane 91%, 9% carbon dioxide, octamethylcyclotetrasiloxane 4.2 mg / ^{m 3,} or less decamethylcyclopentasiloxane 38 mg / ^{m 3,} the siloxane was not removed It was possible to concentrate methane. However, as a result of continuing operation for about half a year, the methane concentration of the refined gas gradually decreased, making it impossible to concentrate methane.

Comparative Example 2
The experiment was performed under the same conditions as in Example 1 except that the operation was performed without passing through the methane concentration section.
The composition of the operation beginning of the purified gas, methane 55%, 45% carbon dioxide, less octamethyl white cyclotetrasiloxane 0.1 mg / ^{m 3,} or less decamethylcyclopentasiloxane 0.1 mg / ^{m 3,} siloxanes removed However, no carbon dioxide was removed.

Example 2
Experiments were performed using an experimental apparatus having the structure shown in FIG.
Methane 55%, 45% carbon dioxide, octamethylcyclotetrasiloxane 4.5 mg / ^{m 3,} intended for sewage sludge digestion gas after desulfurization and dehumidification containing decamethylcyclopentasiloxane 42 mg / ^{m 3.} The experimental conditions are as follows.
(1) Siloxane removal part Type of adsorbent: Activated carbon for gas treatment Superficial velocity SV: 3600 hr ⁻¹
Regeneration method: Thermal swing adsorption method (reduced pressure regeneration by heating gas purge, off
Replacement time 12 hours)
(2) Methane enrichment part Type of adsorbent: Molecular sieve carbon with a pore size of 5 mm Superficial velocity SV: 300 hr ⁻¹
Regeneration method: Pressure swing adsorption method (reduced pressure regeneration, switching time 5 minutes)
The composition of the purified gas, methane 91%, 9% carbon dioxide, less octamethylcyclotetrasiloxane 0.1 mg / ^{m 3,} below decamethylcyclopentasiloxane 0.1 mg / ^{m 3,} stable and carried out over a long period of time The purification performance equivalent to Example 1 was demonstrated. In addition, in this example, the siloxane compound removal part was made a heat swing type regenerative type, so that it was possible to cope with a small amount of adsorbent about 1/10 of the siloxane removal part of Example 1. .

Example 3
Experiments were performed using an experimental apparatus having the structure shown in FIG.
Methane 55%, 45% carbon dioxide, octamethylcyclotetrasiloxane 2.6 mg / ^{m 3,} intended for sewage sludge digestion gas after desulfurization and dehumidification containing decamethylcyclopentasiloxane 38 mg / ^{m 3.} The experimental conditions are as follows.
(1) Siloxane removal part Type of adsorbent: Activated carbon for gas treatment Superficial velocity SV: 3600 hr ⁻¹
Regeneration method: Thermal swing adsorption method [Gas purge (carbon dioxide adsorbent regeneration
Temperature rise regeneration and switching by exhaust gas that is sometimes generated)
12 hours]
(2) Methane enrichment part Type of adsorbent: Molecular sieve carbon with a pore size of 5 mm Superficial velocity SV: 300 hr ⁻¹
Regeneration method: Pressure swing adsorption method (reduced pressure regeneration, switching time 5 minutes)

The composition of the refined gas was 90% methane, 10% carbon dioxide, octamethylcyclotetrasiloxane 0.1 mg / m ³ or less, and decamethylcyclopentasiloxane 0.1 mg / m ³ or less. It was. In addition, in this example, the siloxane compound removal part was made a heat swing type regenerative type, so that it was possible to remove siloxane with a very small amount of adsorbent at a superficial velocity of SV3600 hr ⁻¹ . Further, in the regeneration of the siloxane removal adsorbent, since the exhaust gas mainly composed of carbon dioxide generated during the regeneration of the carbon dioxide removal adsorbent is used as the purge gas, it is not necessary to separately use a purge gas such as nitrogen gas.

Example 4
Experiments were performed using an experimental apparatus having the structure shown in FIG.
Sewage sludge digestion gas after desulfurization and dehumidification containing 55% methane, 45% carbon dioxide, 4.0 mg / m ³ octamethylcyclotetrasiloxane, and 27 mg / m ³ decamethylcyclopentasiloxane was used. The experimental conditions are as follows.
(1) Siloxane removal part Adsorbent type: Resin adsorbent Superficial velocity SV: 600 hr ⁻¹
Regeneration method: Pressure swing adsorption method (2) Methane concentration part Type of adsorbent: Molecular sieve carbon with pore diameter of 5 mm Superficial velocity SV: 300 hr ^-1
Regeneration method: Pressure swing adsorption method (reduced pressure regeneration, switching time 5 minutes)

The composition of the purified gas, methane 90%, 10% carbon dioxide, octamethylcyclotetrasiloxane 0.1 mg / ^{m 3,} in decamethylcyclopentasiloxane 0.1 ~0.13mg / ^{m 3,} stable over a long period of time As a result, purification performance substantially equivalent to that of Example 3 was exhibited. In addition, in this example, the siloxane compound removal part and the methane concentration part are placed in the same device, and the siloxane adsorbent and carbon dioxide adsorbent are adsorbed and regenerated simultaneously by the pressure swing method, so the structure of the device is not only simple The driving operation was extremely easy.

The flow block diagram which showed an example of the digestion gas refinement | purification apparatus of this invention. The flow block diagram which showed the other example of the digestion gas purification apparatus of this invention. The flow block diagram which showed another example of the digestion gas purification apparatus of this invention. The flow block diagram which showed another example of the digestion gas purification apparatus of this invention.

Explanation of symbols

  1: digestion gas after desulfurization / dehumidification, 2: purified gas, 3: exhaust gas, 4: gas compressor, 5: siloxane removal unit, 6: packed bed filled with siloxane adsorbent, 7: methane concentration unit, 8: packed bed filled with carbon dioxide adsorbent, 9: gas pipe, 10: gas purge pipe, 11, 11 ′, 15, 15 ′: switching valve, 12: vacuum pump, 13: heater, 14: gas purge pipe

Claims (9)

  An apparatus for purifying digestive gas containing a siloxane compound, the apparatus comprising a siloxane compound removing unit and a methane concentrating unit downstream thereof.   The said methane concentration part is provided with the pressure swing adsorption | suction apparatus which has a several packed bed filled with the carbon dioxide adsorbent, and has a regeneration means for regenerating this packed bed alternately. Digestion gas purification equipment.   The siloxane compound removal unit includes an adsorption device having a packed layer filled with a siloxane compound adsorbent, or has a plurality of packed layers filled with the adsorbent, and alternately regenerates the packed layer. The apparatus for purifying digestive gas according to claim 1 or 2, further comprising a pressure swing adsorption device and / or a thermal swing adsorption device having a regeneration means.   An apparatus for purifying digestive gas containing a siloxane compound, the apparatus comprising a plurality of packed beds filled with a siloxane compound adsorbent for removing siloxane compounds installed upstream, wherein the packed layers are alternately arranged. A pressure swing adsorption device and / or a thermal swing adsorption device having a regeneration means for regeneration, and a plurality of packed beds filled with a carbon dioxide adsorbent for concentrating methane in digestion gas installed on the downstream side, A pressure swing adsorption device having regeneration means for alternately regenerating the packed bed, and exhaust gas mainly composed of carbon dioxide generated during regeneration of the carbon dioxide adsorbent is used as purge gas for regeneration of siloxane adsorbent An apparatus for purifying digestion gas, comprising a purge pipe for use as a digestion gas.   A purification apparatus for digestion gas containing a siloxane compound, which removes a packed bed filled with a carbon dioxide adsorbent for concentrating methane in the digested gas and a siloxane compound provided upstream of the packed bed Pressure swing having a plurality of packed columns packed with packed siloxane adsorbents packed in the same column, and having a regeneration means for alternately regenerating the adsorbents in the packed columns for each packed column An apparatus for purifying digestion gas, comprising an adsorption device.   In the purification method of the digestion gas containing a siloxane compound, the methane concentration is performed after removing a siloxane compound from the said digestion gas previously, The purification method of the digestion gas characterized by the above-mentioned.   The method for purifying digestive gas according to claim 6, wherein the methane concentration is performed by adsorbing and removing carbon dioxide by a pressure swing adsorption method using an adsorbent.   The digestion gas according to claim 6 or 7, wherein the siloxane compound is removed by adsorption removal with an adsorbent, or a pressure swing adsorption method and / or a thermal swing adsorption method using an adsorbent. Purification method.   In the method for purifying a digestion gas containing a siloxane compound, methane for removing carbon dioxide from the digestion gas after removing the siloxane compound in advance using a pressure swing adsorption method and / or a thermal swing adsorption method using an adsorbent. Concentration is performed by pressure swing adsorption using an adsorbent, and exhaust gas mainly composed of carbon dioxide generated during regeneration of the adsorbent for methane concentration is used as a purge gas for regeneration of the adsorbent that adsorbs the siloxane compound. A method for purifying digestive gas, characterized by being used.

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