JP2010254743A - Apparatus and method for removing siloxane in digestion gas - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a method for removing siloxane in a digestion gas capable of satisfactorily removing the siloxane contained in a digestion gas. <P>SOLUTION: This method for removing the siloxane in a digestion gas comprises: a compressing process for compressing a digestion gas containing methane, siloxane, hydrocarbons other than methane and water by a compressor 10 to obtain a compressed gas; a cooling-dehumidifying process for cooling the compressed gas by a cooling-dehumidifier 20 to generate a condensate and removing the condensate to obtain a dehumidified gas; a decompressing process for decompressing the dehumidified gas through a decompressing valve 40 to obtain a decompressed gas; and a siloxane removing process for flowing the decompressed gas through a porous adsorbent in an adsorber 50 to adsorb the siloxane. <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

  The present invention relates to a siloxane removal apparatus and a siloxane removal method for removing siloxane contained in digestion gas generated by biological treatment of organic waste.

  Biologically, for example, by fermenting organic waste generated in sewage treatment plants, food factories, beer factories, livestock breeding plants, etc., such as sludge, garbage, and human waste in a tank at about 35 ° C. When processed, digestion gas containing methane, carbon dioxide, hydrogen sulfide and the like is generated. In recent years, it has been studied to effectively use methane contained in the digestion gas as an energy source. For example, it is considered to generate electricity by supplying methane recovered from digestion gas to a power generation facility such as a gas turbine.

By the way, the digestion gas usually contains a small amount of siloxane. Therefore, when digestion gas is burned in the power generation facility, silica is generated due to oxidation of siloxane, and this silica sometimes causes wear of the power generation facility. For this reason, removal of siloxane in digestion gas is required.
In response to this requirement, Patent Documents 1 and 2 propose a method of removing dimethylsiloxane in digested gas by passing digested gas through activated carbon.
Patent Document 3 proposes a method for removing siloxane in the digestion gas by cooling the digestion gas and then passing it through a porous adsorbent.
Patent Document 4 proposes activated carbon having an average pore diameter and pore volume suitable for siloxane removal.

JP 2003-225525 A JP 2002-058996 A JP 2002-138851 A JP 2005-177737 A

However, even if the siloxane removal method described in Patent Documents 1 to 3 and the activated carbon described in Patent Document 4 are applied, it cannot be said that the amount of siloxane removal is sufficient.
The present invention has been made in view of the above circumstances, and an object thereof is to provide a digestion gas siloxane removal apparatus and a siloxane removal method capable of sufficiently removing siloxane contained in digestion gas.

The digestion gas contains not only methane and siloxane, but also hydrocarbons other than methane (alkanes such as toluene and tridecane, alkenes) and moisture (water vapor and droplets). As a result of investigation by the present inventor, some of the hydrocarbons other than methane have an affinity for the porous adsorbent that is equal to or higher than that of siloxane. It has been found that the amount of adsorption is reduced, and that some hydrocarbons other than methane desorb siloxane adsorbed on the porous adsorbent.
And based on this knowledge, as a result of studying means for increasing the amount of siloxane adsorbed by the porous adsorbent, the following siloxane removal apparatus and siloxane removal method were invented.

[1] A compressor that compresses digestion gas containing methane, siloxane, hydrocarbons other than methane, and moisture to obtain compressed gas;
A cooler that cools the compressed gas to generate a condensate, and a condensate discharge valve that discharges the condensate; a dehumidifier that removes the condensate and obtains dehumidified gas;
A pressure reducing valve for depressurizing the dehumidifying gas to obtain a decompressed gas;
An apparatus for removing siloxane from digestive gas, comprising: an adsorber filled with a porous adsorbent that adsorbs siloxane contained in the decompressed gas.
[2] A gas-liquid separator that contains the condensate discharged from the cooling dehumidifier and a part of the dehumidifying gas accompanying the condensate and separates the gas-liquid,
Return piping for returning the gas obtained by the gas-liquid separator to the compressor;
The digestion gas siloxane removing apparatus according to [1], further comprising a discharge pipe for discharging the liquid obtained by the gas-liquid separator.
[3] According to [1] or [2], further comprising a tide releasing humidifier filled with a deliquescent material that absorbs moisture contained in the dehumidified gas between the cooling dehumidifier and the pressure reducing valve. The digestion gas siloxane removal apparatus as described.
[4] The siloxane removal apparatus for digestive gas according to any one of [1] to [3], wherein the porous adsorbent filled in the adsorber is coconut shell activated carbon.
[5] A compression step of compressing digestion gas containing methane, siloxane, hydrocarbons other than methane, and moisture to obtain compressed gas;
A cooling and dehumidifying step of cooling the compressed gas to generate a condensate and removing the condensate to obtain a dehumidified gas;
A depressurizing step of depressurizing the dehumidifying gas to obtain a depressurized gas;
And a siloxane removal step of adsorbing siloxane by passing the reduced-pressure gas through a porous adsorbent.
[6] A gas-liquid separation step in which the condensate removed in the cooling dehumidification step and a part of the dehumidifying gas accompanying the condensate are stored in a gas-liquid separator and separated into gas and liquid,
A return process for returning the gas obtained in the gas-liquid separation process to the compression process;
The method for removing siloxane from digestive gas according to [5], further comprising a discharge step of discharging the liquid obtained in the gas-liquid separation step from the gas-liquid separator.
[7] In the compression step, the digestion gas is compressed to a pressure of 0.75 MPa (gauge pressure) or more, in the cooling dehumidification step, the compressed gas is cooled to 10 ° C. or less, and in the decompression step, the dehumidification gas is reduced to 0.15 MPa or more. [5] or [6], which is characterized in that the siloxane removal method of digestion gas.

  According to the digestion gas siloxane removal apparatus and siloxane removal method of the present invention, the siloxane contained in the digestion gas can be sufficiently removed.

It is a schematic diagram which shows one Embodiment of the siloxane removal apparatus of the digestive gas of this invention.

<Digestion gas siloxane removal device>
An embodiment of a digestion gas siloxane removal apparatus (hereinafter abbreviated as a siloxane removal apparatus) of the present invention will be described.
FIG. 1 shows a siloxane removal apparatus according to this embodiment. The siloxane removal apparatus 1 of this embodiment is an apparatus that removes siloxane from digestion gas containing methane, siloxane, hydrocarbons other than methane, and moisture.
Specifically, the siloxane removal apparatus 1 according to the present embodiment includes a compressor 10 that compresses digestion gas to obtain a compressed gas, and a cooling dehumidifier that is connected to the compressor 10 and cools the compressed gas to obtain a dehumidified gas. 20 and a tide release humidifier 30 that is connected to the cooling dehumidifier 20 and further dehumidifies the dehumidified gas, and a pressure reducing valve that is connected to the tide release humidifier 30 and depressurizes the dehumidified gas that has passed through the tide release humidifier 30 to obtain a decompressed gas. 40 and an adsorber 50 connected to the pressure reducing valve 40 and through which the pressure reducing gas is passed.
Further, the siloxane removal apparatus 1 of this embodiment includes a gas holder 60 connected to the upstream side of the compressor 10 and a gas-liquid separator 70 connected to the cooling dehumidifier 20.
Furthermore, the siloxane removal apparatus 1 according to the present embodiment includes a first pipe 91 for connecting the compressor 10 to the gas holder 60, and a second pipe 92 for connecting the cooling dehumidifier 20 to the compressor 10. The third pipe 93 for connecting the tide release humidifier 30 to the cooling dehumidifier 20, the fourth pipe 94 for connecting the pressure reducing valve 40 to the tide release humidifier 30, and the adsorber 50 on the pressure reducing valve 40 A fifth pipe 95 for connection, a sixth pipe 96 for transferring digestion gas after removal of siloxane from the adsorber 50, and a seventh pipe for connecting the gas-liquid separator 70 to the cooling dehumidifier 20. Pipe 97, an eighth pipe (return pipe) 98 for connecting the first pipe 91 to the gas-liquid separator 70, and a ninth pipe for discharging the liquid from the gas-liquid separator 70 ( Discharge piping) 99.

The compressor 10 compresses digestion gas to a predetermined pressure. For example, a screw type, a reciprocating type, a swinging type, or a diaphragm type can be used.
In terms of preventing oil from being mixed into the compressed gas, the compressor 10 is preferably an oil-free type. The compressor 10 is preferably one that can control the rotation speed by an inverter.

The cooling dehumidifier 20 includes a cooler 21 and a condensate discharge valve 22.
The cooler 21 cools the compressed gas and condenses some of the water vapor, hydrocarbons, and siloxane in the compressed gas to generate a condensate.
As the cooler 21, for example, an indirect cooling type that cools a pipe through which digestion gas passes with a cooling medium (for example, cold water) can be used.

The condensate discharge valve 22 is an open / close valve for discharging the condensate generated in the cooler 21 from the cooling dehumidifier 20 and removing it. The condensate discharge valve 22 is preferably one that automatically opens the valve to discharge the condensate when the production amount of the condensate reaches a predetermined amount (for example, an auto drain trap or an electromagnetic valve).
When the condensate discharge valve 22 is opened, the primary side pressure is high, so that a gas-liquid mixed phase flow is formed. Therefore, part of the dehumidified gas is also discharged along with the condensate.

The tide release humidifier 30 is filled with a deliquescent material that absorbs moisture. According to the tide release wetter 30, moisture remaining in the dehumidified gas can be selectively removed using the deliquescence action of the deliquescent material. Here, the deliquescence action is a phenomenon in which a solid absorbs water vapor contained in the surrounding gas and dissolves by the absorbed moisture.
Examples of the deliquescent material filled in the adsorption remover 39 include calcium chloride, magnesium chloride, and crude sodium chloride.

  The pressure reducing valve 40 depressurizes the dehumidified gas, and examples thereof include a direct acting type and a pilot actuating type. Usually, the pressure reducing valve 40 detects the secondary pressure and makes the secondary pressure constant.

The adsorber 50 is filled with a porous adsorbent that adsorbs siloxane.
Examples of the porous adsorbent include activated carbon (for example, coconut shell activated carbon, wood activated carbon, petroleum activated carbon, etc.), artificial zeolite, natural zeolite, silica gel and the like.
In the siloxane removal apparatus 1 of this embodiment, it is preferable to use activated carbon as the porous adsorbent for the following reasons.
In the gas-liquid separator 70, some hydrocarbons other than methane contained in the condensate are volatilized. At that time, the smaller the molecular weight of the hydrocarbons and the lower the boiling point, the larger the volatilization amount. However, the lower the molecular weight of the hydrocarbons and the lower the boiling point, the lower the affinity for the activated carbon. Therefore, if activated carbon is used as the porous adsorbent for removing siloxane, even if hydrocarbons volatilize in the gas-liquid separator 70, a decrease in the amount of siloxane adsorbed can be suppressed.

Among activated carbons, coconut shell activated carbon is preferable because siloxane is more easily absorbed and removed.
Further, among the coconut shell activated carbons, those having a specific surface area of 1,000 m ² / g or more, a pore volume of 0.45 to 0.85 mL / g, and a peak of pore distribution of 0.7 to 1.2 nm are available. preferable. Those having the specific surface area, pore volume and pore distribution peaks in the above ranges are easily obtained, and are particularly suitable for adsorption and removal of siloxane.

  The gas holder 60 temporarily stores digestion gas. The gas holder 60 is preferably a variable capacity type. If the capacity is variable, it is possible to detect the volume (that is, the digestion gas storage amount), and to control subsequent devices such as the compressor 10 according to the volume.

  The gas-liquid separator 70 stores the condensate discharged from the cooling dehumidifier 20 and a part of the dehumidifying gas accompanying the condensate for gas-liquid separation. An airtight container can be used as the gas-liquid separator 70. There is no restriction | limiting in the external shape of an airtight container, For example, a cylindrical body, a rectangular parallelepiped, a spherical body etc. can be used.

Inside the gas-liquid separator 70 of the present embodiment, a collection material 71 for capturing droplets in the gas is installed in the vicinity of the upper surface. By returning the gas from which the droplets have been removed to the compressor 10, mechanical wear and the like in the compressor 10 can be prevented.
As the collection material 71, for example, glass fiber filter paper, element filter, bag filter, eliminator, or the like can be used.

In the present embodiment example, the seventh pipe 97 is connected to the gas-liquid separator 70 at a position higher than the liquid level of the liquid in the gas-liquid separator 70 (but lower than the collection material 71). Yes. If the seventh pipe 97 is connected to a position higher than the liquid level in the gas-liquid separator 70, the condensed liquid and the accompanying dehumidifying gas are introduced into the gas phase portion, and the gas-liquid separator 70 Since the liquid can be further prevented from being entrained, the processing load on the collecting material 71 can be minimized.
The eighth pipe 98 is connected to the upper surface of the gas-liquid separator 70, but the position is not limited as long as it is above the collection material 71. If the eighth pipe 98 is above the collection material 71, it is possible to prevent the liquid from being mixed into the gas returned to the first pipe 91 due to the sedimentation effect of the droplets due to gravity.
The ninth pipe 99 is connected to the bottom surface of the gas-liquid separator 70, and the ninth pipe 99 is a U-shaped pipe. If the ninth pipe 99 is connected to the bottom surface, the liquid can be discharged without releasing the gas to the outside.
Here, the water head difference Δh between the liquid level H ₁ in the gas-liquid separator 70 and the highest point H ₂ of the ninth pipe 99 is appropriately set according to the pressure in the gas-liquid separator 70. That is, the water head difference Δh indicates that the liquid in the gas-liquid separator 70 is discharged via the ninth pipe 99 when the pressure in the gas-liquid separator 70 increases or the liquid increases, When there is no increase in the liquid, it is set so that the liquid is not discharged.

<Method for removing siloxane from digestion gas>
An embodiment of a siloxane removal method using the siloxane removal apparatus 1 will be described.
The siloxane removal method of the present embodiment includes a compression step of compressing digestion gas with the compressor 10 to obtain compressed gas, and cooling the compressed gas with the cooling dehumidifier 20 to generate a condensate. A cooling and dehumidifying step for removing the dehumidified gas by removing the tide dehumidifying step for further dehumidifying the dehumidified gas by the tide releasing humidifier 30; And a siloxane removal step of removing siloxane contained in the decompressed gas at 50.
Furthermore, the siloxane removal method of the present embodiment includes a gas-liquid separation step in which the condensed liquid generated in the cooling dehumidifier 20 and the dehumidified gas accompanying the condensed liquid are accommodated in the gas-liquid separator 70 and gas-liquid separation is performed. It has the return process which returns the gas isolate | separated in the gas-liquid separator 70 to the 1st piping 91, and the discharge process which discharges the liquid obtained in the gas-liquid separator 70 from the gas-liquid separator 70.

The digestion gas used in the siloxane removal method contains at least methane, siloxane, hydrocarbons other than methane, and moisture. Moreover, you may include components (for example, hydrogen sulfide, nitrogen, oxygen, a carbon dioxide, etc.) other than these.
Examples of the siloxane contained in the digestion gas include chain siloxanes such as methoxytrimethylsilane, dimethoxydimethylsilane, hexamethyldisiloxane, octamethyltrisiloxane, decamethyltetrasiloxane, and dodecamethylpentasiloxane. In addition, cyclic siloxanes such as hexamethylcyclotrisiloxane (D3 form), octamethylcyclotetrasiloxane (D4 form), decamethylcyclopentasiloxane (D5 form), and dodecamethylcyclohexasiloxane (D6 form) are included. .
The pressure of the digestion gas can be set to, for example, 1 to 3 kPa (gauge pressure).

  In the compression step, it is preferable to compress the digestion gas transferred by the first pipe 91 to a pressure of 0.75 MPa (gauge pressure) or more. Since the hydrocarbons contained in the digestion gas have a low vapor pressure, if the pressure is low, the hydrocarbons may not be condensed even if cooled in the cooling and dehumidifying step. However, if the digestion gas is compressed to a pressure of 0.75 MPa or more, the hydrocarbons are easily condensed by cooling in the cooling and dehumidifying step.

  In the cooling and dehumidifying step, not only moisture contained in the compressed gas but also hydrocarbons other than methane and siloxane can be condensed by cooling the compressed gas transferred by the second pipe 92. Therefore, the siloxane content, the hydrocarbon content other than methane, and the water content of the dehumidified gas obtained in the cooling and dehumidifying step are less than the amount contained in the compressed gas.

In the cooling dehumidification step, the lower the gas temperature, the lower the siloxane concentration in the resulting dehumidified gas. However, the degree of reduction is large up to 10 ° C., but the degree of reduction is small below 10 ° C. Therefore, in order to efficiently remove as much siloxane as possible in the cooling and dehumidifying step, it is preferable to cool the resulting dehumidified gas so that the temperature is 10 ° C. or lower.
Moreover, when it cools so that the temperature of a dehumidification gas may be 10 degrees C or less in a cooling dehumidification process, since a dew point will be 10 degrees C or less, dew condensation can be prevented even if temperature becomes high at a latter process.
Moreover, it is preferable to cool so that the temperature of the dehumidification gas obtained may not become less than 0 degreeC in the point of preventing the piping blockage by freezing of water | moisture content.

  The condensate obtained in the cooling dehumidification step contains siloxanes, hydrocarbons other than methane, and water. When this condensate is discharged from the condensate discharge valve 22, some dehumidifying gas is accompanied.

In the tide release moisture process, the dehumidified gas transferred by the third pipe 93 is passed through the tide release humidifier 30, the moisture contained in the dehumidified gas is absorbed by the deliquescent material, and the dehumidified gas is further dehumidified. Since the dehumidification by the deliquescent substance is non-powered, the amount of water in the dehumidified gas can be reduced without increasing the energy consumption in the tide release moisture process.
If the dehumidified gas is further dehumidified by the tide release moisture process, when the cooling temperature is set to 0 ° C. or higher in the cooling dehumidification step (when the dew point is set to 0 ° C. or higher), the ambient temperature around the siloxane removal device 1 is increased. Even when the temperature is below freezing, moisture contained in the gas can be prevented from freezing and the piping can be blocked.

In the decompression step, the dehumidifying gas transferred from the decompression valve 40 is decompressed by the fourth pipe 94, thereby reducing the water vapor pressure in the gas and evaporating water droplets in the micrometer order contained in the dehumidifying gas. Although micrometer-order water droplets contained in the dehumidified gas are very small, when a large amount of dehumidified gas comes into contact with the porous adsorbent, the water droplet covers the adsorbent surface and inhibits siloxane removal. Therefore, by evaporating the water droplets in the decompression step, inhibition of siloxane adsorption to the porous adsorbent by the water droplets in the siloxane removal step can be prevented, and the siloxane removal capability can be enhanced.
For example, a dehumidifying gas (temperature: 3.5 to 7.0 ° C.) with a pressure of 0.75 to 0.80 MPa (gauge pressure) is set so that the pressure after depressurization is 0.52 to 0.59 MPa (gauge pressure). When the pressure is reduced to 1, the digestion gas throughput until the siloxane breaks through the porous adsorbent is about 420,000 m ³ (standard state) in terms of 1 m ^{3 of the} porous adsorbent. On the other hand, when the pressure is not reduced, the digestion gas throughput until the siloxane breaks through the porous adsorbent is about 300,000 m ³ (standard state) in terms of 1 m ^{3 of the} porous adsorbent.
The decompression width in the decompression step is preferably 0.15 MPa or more because the siloxane removal ability in the siloxane removal step becomes higher.

  As a method for removing water droplets, a method using a filter is generally known, and it is desirable to install a filter before the decompression step or before the siloxane removal step. Since small water droplets pass through the filter, the filter alone cannot prevent inhibition of siloxane adsorption in the porous adsorbent. Therefore, it is difficult to achieve the object of the present invention unless the decompression step is performed.

In the siloxane removal step, the decompressed gas transferred from the decompression valve 40 through the fifth pipe 95 is adsorbed through the porous adsorbent filled in the adsorber 50. As a result, the siloxane content in the gas that has passed through the adsorber 50 is less than before the passage.
In the siloxane removal step, the linear velocity of the reduced pressure gas is preferably 0.1 m / second or less. If the linear velocity of the decompressed gas is set to 0.1 m / sec or less, the length of the porous adsorbent (adsorption zone) where the adsorption capacity remains when the porous adsorbent breaks through can be shortened. High efficiency can be achieved.

In the gas-liquid separation step, the condensate contained in the gas-liquid separator 70 and the dehumidification gas accompanying the condensate are mixed with liquids such as water, high-boiling hydrocarbons and siloxane, methane, low-boiling carbonization due to the difference in specific gravity. Separated into gases such as hydrogen. The gas pressure in the gas-liquid separation step is, for example, 1 to 3 kPa (gauge pressure).
In the present embodiment example, the obtained gas is passed through the collection material 71 to capture and remove the droplets, and then returned to the first pipe 91 via the ninth pipe 99 in the return process. Therefore, the gas separated by the gas-liquid separator 70 can be supplied to the cooling dehumidifier 20 again.
In the present embodiment, when the pressure in the gas-liquid separator 70 increases, the liquid in the eighth pipe 98 is discharged beyond the highest point H ₂ of the eighth pipe 98 (discharge process). ). Therefore, in the discharge process in the present embodiment, the liquid can be discharged without using power.

The digestion gas from which siloxane has been removed by the siloxane removal apparatus 1 and the removal method is transferred from the adsorber 50 to a power generation facility or the like via the sixth pipe 96 and consumed as an energy source.
Here, examples of the power generation equipment include an internal combustion engine such as a micro gas turbine and a gas engine, and a fuel cell.

(Function and effect)
In the siloxane removal apparatus 1 and the siloxane removal method of the above embodiment, since the digestion gas containing methane, siloxane, hydrocarbons other than methane, and moisture is cooled by the cooling dehumidifier 20, it was included in the digestion gas. Some siloxanes, hydrocarbons and moisture can be condensed. By removing this condensate, the contents of hydrocarbons other than siloxane and methane and moisture in the gas supplied to the adsorber 50 can be reduced. In addition, since the digestion gas to be cooled is compressed in advance by the compressor 10 so that the amount of condensate produced is increased, the removal amount of hydrocarbons and moisture other than siloxane and methane is large. Therefore, the content of siloxane contained in the gas supplied to the adsorber 50 can be reduced in advance, and hydrocarbons that are inhibitors of siloxane adsorption in the porous adsorbent can be reduced.
Further, since the digestion gas is dehumidified by the cooling dehumidifier 20 and further dehumidified by the tide release humidifier 30 and depressurized by the pressure reducing valve 40, the gas introduced into the adsorber 50 has a small amount of water, A small proportion of the moisture contained in the gas exists in the form of droplets. Therefore, the amount of siloxane removed in the adsorber 50 can be increased because there is little moisture that hinders the adsorption of siloxane to the porous adsorbent.
Therefore, according to the siloxane removal apparatus 1 and the siloxane removal method of the above embodiment, the siloxane contained in the digestion gas can be sufficiently removed.

In the above embodiment, the dehumidified gas discharged from the cooling dehumidifier 20 along with the condensate is collected by the gas-liquid separator 70 and returned to the first pipe 91 via the eighth pipe 98. To do. Therefore, most of methane contained in digestion gas can be used as an energy source. In addition, since methane has a high global warming potential, the burden on the environment can be reduced by avoiding release to the outside. Moreover, when hydrogen sulfide is contained in digestion gas, generation | occurrence | production of malodor can be prevented.
Furthermore, since the siloxane removal apparatus 1 of the above embodiment has a simple configuration, it can easily remove siloxane and can be easily downsized.

(Other embodiment examples)
Note that the present invention is not limited to the above embodiment. For example, the tide release humidifier 30 in the siloxane removal apparatus 1 may be omitted. However, in order to increase the amount of siloxane removal by lowering the humidity of the dehumidifying gas, it is preferable to provide the tide release humidifier 30.
Moreover, in the siloxane removal apparatus 1, the gas holder 60 may be omitted, and the first pipe 91 may be directly connected to equipment for generating digestion gas.
The ninth pipe 99 may not be a U-shaped tube that is configured to discharge liquid when the pressure in the gas-liquid separator 70 increases. When the U-shaped tube is not used, for example, when a straight pipe directed downward from the gas-liquid separator 70 is used as the ninth pipe 99, the liquid level in the gas-liquid separator 70 has a predetermined height. It is preferable to install an electromagnetic valve in the ninth pipe 99 that opens when the pressure is reached.
Further, the gas-liquid separator 70 and the seventh pipe 97, the eighth pipe 98, and the ninth pipe 99 attached to the gas-liquid separator 70 may be omitted. However, as described above, in terms of increasing the use efficiency of methane in the digestion gas, the gas-liquid separator 70 and the seventh pipe 97, the eighth pipe 98, and the ninth attached to the gas-liquid separator 70 are used. It is preferable that the pipe 99 is provided.
When a digestion gas utilization facility other than the power generation device (for example, a digestion tank heating boiler) is connected to the gas holder 60, a pipe for connecting the adsorber 50 and the gas holder 60 may be provided. When such a pipe is provided, when a large amount of digestion gas is consumed in a digestion gas utilization facility other than the power generation device, the power generation device is stopped and the supply of the digestion gas is stopped, and the digestion gas stored in the adsorber 50 is absorbed and stored. The gas can be returned to the gas holder 60.

DESCRIPTION OF SYMBOLS 1 Siloxane removal apparatus 10 Compressor 20 Cooling dehumidifier 21 Cooler 22 Condensate discharge valve 30 Tidal release humidifier 40 Pressure reducing valve 50 Adsorber 60 Gas holder 70 Gas-liquid separator 71 Collection material 91 1st piping 92 2nd piping 93 3rd piping 94 4th piping 95 5th piping 96 6th piping 97 7th piping 98 8th piping (pipe for return)
99 9th pipe (pipe for discharge)

Claims (7)

A compressor that compresses digestion gas containing methane, siloxane, hydrocarbons other than methane, and moisture to obtain compressed gas;
A cooler that cools the compressed gas to generate a condensate, and a condensate discharge valve that discharges the condensate; a dehumidifier that removes the condensate and obtains dehumidified gas;
A pressure reducing valve for depressurizing the dehumidifying gas to obtain a decompressed gas;
An apparatus for removing siloxane from digestive gas, comprising: an adsorber filled with a porous adsorbent that adsorbs siloxane contained in the decompressed gas. A gas-liquid separator that contains the condensate discharged from the cooling dehumidifier and a part of the dehumidified gas accompanying the condensate and separates the gas-liquid,
Return piping for returning the gas obtained by the gas-liquid separator to the compressor;
The digestion gas siloxane removing apparatus according to claim 1, further comprising a discharge pipe for discharging the liquid obtained by the gas-liquid separator.   The digester gas according to claim 1 or 2, further comprising a tide dehumidifier filled with a deliquescent material that absorbs moisture contained in the dehumidified gas between a cooling dehumidifier and a pressure reducing valve. Siloxane removal device.   The siloxane removal apparatus for digestive gas according to any one of claims 1 to 3, wherein the porous adsorbent filled in the adsorber is coconut shell activated carbon. A compression step of compressing a digestion gas containing methane, siloxane, hydrocarbons other than methane, and moisture to obtain a compressed gas;
A cooling and dehumidifying step of cooling the compressed gas to generate a condensate and removing the condensate to obtain a dehumidified gas;
A depressurizing step of depressurizing the dehumidifying gas to obtain a depressurized gas;
And a siloxane removal step of adsorbing siloxane by passing the reduced-pressure gas through a porous adsorbent. A gas-liquid separation step in which the condensate removed in the cooling and dehumidification step and a part of the dehumidified gas accompanying the condensate are stored in a gas-liquid separator and separated into gas and liquid;
A return process for returning the gas obtained in the gas-liquid separation process to the compression process;
6. The method for removing siloxane from digestive gas according to claim 5, further comprising a discharge step of discharging the liquid obtained in the gas-liquid separation step from the gas-liquid separator.   The digestion gas is compressed to a pressure of 0.75 MPa (gauge pressure) or more in the compression step, the compression gas is cooled to 10 ° C. or less in the cooling dehumidification step, and the dehumidification gas is reduced to 0.15 MPa or more in the decompression step. The method for removing siloxane from digestive gas according to claim 5 or 6.

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