JP2002069468A - Method and apparatus for purifying digested gas - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an apparatus for purifying a digested gas which apparatus is capable of removing inexpensively and efficiently a siloxane compound in a digested gas of a sewage sludge. SOLUTION: This apparatus is for removing the siloxane compound from the digested gas of the sewage sludge containing the siloxane compound. This apparatus is characterized by providing with a dehumidifying cooler 1 for condensing said siloxane compound contained in said digested gas together with water by indirectly cooling said digested gas by heat exchanging with a cooling medium, and a packed bed 11 arranged downstream of said dehumidifying cooler and filled with a porous adsorbent 14 for removing by adsorption of a residue siloxane compound in said digested gas.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method and an apparatus for purifying a digestion gas containing a siloxane compound generated in a digestion process of sewage sludge.

[0002]

2. Description of the Related Art In recent years, reduction of CO ₂ has been promoted as one of the measures against global warming. For example, in a sewage treatment plant, power generation facilities are installed and self-supplied / purchased, thereby improving energy efficiency. Increasingly, there is an increasing number of cases of achieving efficient use and reducing CO ₂ emissions.

That is, in a sewage treatment facility, accumulated sewage is concentrated to obtain sludge containing various organic substances, which are anaerobically digested by the action of microorganisms. The mainstream is a system in which combustible gas (digestion gas) mainly composed of methane obtained in this process is supplied to power generation equipment such as a gas engine and a gas turbine to obtain electric power.

[0004] However, with the increase in the diffusion rate of sewers and changes in lifestyles, consumption of hair finishing agents such as shampoos and rinses, and water repellents such as car wax increases.
A large amount of siloxane compounds contained therein have flowed down into sewage.

[0005] The siloxane compound refers to a compound having a chain or cyclic structure having a siloxane bond (Si-O-Si) as a basic skeleton. As the chain compound, for example,
Examples include methoxytrimethylsilane, dimethoxydimethylsilane, hexamethyldisiloxane, octamethyltrisiloxane, decamethyltetrasiloxane, and dodecamethylpentasiloxane, and examples of the cyclic compound include hexamethylcyclotrisiloxane (D3
Isomer), octamethylcyclotetrasiloxane (D4
Isomer), decamethylcyclopentasiloxane (D5 isomer),
And dodecamethylcyclohexasiloxane (D6 form)
And the like. The compounds listed here have a functional group in the compound composed of a methyl group, but a compound substituted with a hydrocarbon group similar to a methyl group or a compound substituted with fluorine, chlorine, or the like instead of hydrogen is also included. In addition, there is a polypolymer compound having a large molecular weight.

The siloxane compound is present in the sewage in a form adsorbed on the sludge because most of the siloxane compound is insoluble in water, but volatilizes to the digestion gas side in a subsequent digestion process.
That is, the siloxane compound was present together with methane, which is a fuel gas for power generation, and flowed into the subsequent gas engine. The siloxane compound flowing into the gas engine becomes silica (SiO ₂ ) in a combustion chamber in the engine and adheres and precipitates on a cylinder head and other parts in the engine. As a result, there has been a problem that the engine is worn or deteriorated.

[0007] Further, the engine exhaust gas which has passed through a power generation facility such as a gas engine is subjected to, for example, nitrogen oxide treatment.
The waste gas is introduced into the denitration catalyst tower and treated. Since silica (SiO ₂ ) is contained in the exhaust gas, powdery silica (SiO ₂ ) in the exhaust gas precipitates on the surface of the catalyst. Since the powdery silica covers the surface of the catalyst in this way, and a part of the silica penetrates into the inside of the catalyst, there has been a problem that the catalytic activity is deteriorated and the desired removal of nitrogen oxides cannot be achieved.

Conventionally, without implementing effective means for directly avoiding the problems caused by the above-mentioned siloxane compounds, it is necessary to separately increase the frequency of maintenance and inspection of the engine and the frequency of replacement of the denitration catalyst. That is the current situation.

[0009]

As described above, a digestion gas containing a siloxane compound generated from a digestion process in a sewage treatment plant converts silica (SiO ₂ ) in the engine during a combustion process in a subsequent gas engine. This causes wear and deterioration of each part of the engine. Further, even in the latter stage of the denitration catalyst, there was a problem that silica (SiO ₂ ) covered the catalyst surface and deteriorated the denitration performance.

On the other hand, exhaust gas and air-conditioning exhaust gas from various factories, such as printing factories that handle organic solvents and organic silicon, also contain siloxane compounds. In order to remove such siloxane compounds, combustion means, solvent absorption methods, and the like are used. And so on. However, since the siloxane compound has a low concentration, it is difficult to completely burn it, and it cannot be sufficiently removed by means of burning. On the other hand, in the solvent absorption method, a solvent for absorbing the siloxane compound is separately required, and the treatment of the absorbed solvent is complicated, resulting in a problem that the cost is enormous.

It is an object of the present invention to provide a method and an apparatus for purifying a digested gas capable of efficiently and inexpensively removing a siloxane compound in a sewage sludge digested gas containing a siloxane compound to obtain a purified gas. And

[0012]

According to the present invention, there is provided a method of removing a siloxane compound from a sewage sludge digested gas containing a siloxane compound, wherein the digested gas is heated by a cooling medium. A method for purifying a digested gas, comprising a step of exchanging and indirectly cooling and condensing a siloxane compound contained in the digested gas with moisture to separate the siloxane compound from the digested gas. .

As described above, since the siloxane compound in the digested gas is condensed with water and separated by indirectly cooling with the cooling medium, and the digested gas is purified, the power generation equipment such as a gas engine and the denitration equipment at the subsequent stage are used. Silica (SiO ₂ ) derived from a siloxane compound is not precipitated. For this reason, it is possible to avoid abrasion and deterioration of the engine parts as in the related art. Further, the problem of deterioration of the denitration catalyst tower catalyst can be avoided beforehand because the siloxane compound in the gas has been removed. As a result, the frequency of maintenance and inspection of the power generation equipment and the frequency of replacement of the catalyst in the denitration catalyst tower can be significantly reduced.

In the method of the present invention, the cooling medium is:
It is preferably cold water of 10 ° C. or less.

By using cold water of 10 ° C. or less as a cooling medium for indirect cooling, for example, a siloxane compound can be converted from a digestive gas in an inexpensive and simple manner without using a CFC-based cooling medium that adversely affects the air environment. It becomes possible to separate. Furthermore, since the cooling temperature of the digestive gas, that is, the siloxane compound can be reduced to approximately 10 ° C. or less by setting the temperature of the cold water to 10 ° C. or less, the temperature is low even when the concentration of the siloxane compound is relatively low. Therefore, the condensation efficiency can be improved.

Further, in the digestion gas purification method of the present invention, the digestion gas from which the siloxane compound has been separated by the indirect cooling is passed through a packed bed filled with a porous adsorbent, and the digested gas is passed through the porous adsorbent. Preferably, the method further comprises a step of removing the siloxane compound remaining in the siloxane compound-containing gas by adsorbing the siloxane compound in the gas.

As described above, after the indirect cooling by the cooling medium is performed, the digestion gas is passed through the packed bed filled with the porous filler to adsorb and remove the siloxane compound. Even if the siloxane compound that cannot be separated into the gas remains in the digested gas, the digested gas can be sufficiently purified by adsorbing and removing the siloxane gas. Therefore, it is possible to further reduce the frequency of maintenance and inspection of the power generation equipment such as a gas engine and the denitration equipment and the frequency of catalyst replacement in the latter stage.

Further, according to the present invention, there is provided an apparatus for removing a siloxane compound from a sewage sludge digested gas containing a siloxane compound, wherein the digested gas is heat-exchanged with a cooling medium to indirectly cool the digested gas. A dehumidifying cooler that condenses the siloxane compound contained in the gas together with moisture and a porous adsorbent that is installed at a subsequent stage of the dehumidifying cooler and adsorbs and removes the siloxane compound remaining in the digested gas. A digestion gas purification apparatus, comprising:

The siloxane compound contained in the digested gas is separated and removed by indirect cooling with a dehumidifying cooler, and the siloxane compound slightly remaining in the digested gas is adsorbed and removed by the packed bed, so that it flows out to the subsequent stage. The amount of siloxane compound can be reliably reduced or eliminated.
Therefore, silica (SiO ₂ ) derived from a siloxane compound is not deposited in a power generation facility such as a gas engine or a denitration facility in a subsequent stage. For this reason, it is possible to avoid abrasion and deterioration of the engine parts as in the related art. Further, the problem of deterioration of the denitration catalyst tower catalyst can be more reliably avoided by removing the siloxane compound in the gas.

[0020]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described below in detail with reference to the drawings.

FIG. 1 is a flow chart showing an example of a sewage sludge digestion gas power generation system to which the present invention is applied. In addition,
In FIG. 1, details of peripheral devices are omitted for simplification of the description.

The sewage collected at the sewage treatment plant is subjected to concentration and other treatments. The sludge containing various organic substances obtained here is subjected to a digestion gas generator (eg, an egg-type digestion tank, etc.) by the action of microorganisms. Anaerobic digestion. The combustible gas (digestion gas) mainly composed of methane obtained in this process,
After being subjected to desulfurization treatment, mist removal treatment, and the like, it is stored in the digestion gas tank 24.

The digestion gas stored in the digestion gas tank 24 contains a siloxane compound derived from sewage, for example, 10 to 2 times.
It is contained at a concentration of 00 mg / m ³ . The siloxane compound contained herein refers to a siloxane bond (Si-O-
A compound having a chain structure or a cyclic structure having Si) as a basic skeleton. Examples of the chain compound include methoxytrimethylsilane, dimethoxydimethylsilane, hexamethyldisiloxane, octamethyltrisiloxane, decamethyltetrasiloxane, and dodecamethylpentasiloxane, and examples of the cyclic compound include hexamethylcyclotrisiloxane. Siloxane (D3), octamethylcyclotetrasiloxane (D4), decamethylcyclopentasiloxane (D5), and dodecamethylcyclohexasiloxane (D6). The functional group in the siloxane compound does not need to be composed of a methyl group, and may be substituted with a hydrocarbon group similar to a methyl group. Alternatively, a siloxane compound substituted by fluorine, chlorine, or the like instead of hydrogen is included, and a polypolymer compound having a large molecular weight is also included. In particular, the present inventors have found that the cyclic structures of octamethylcyclotetrasiloxane (D4 isomer) and decamethylcyclopentasiloxane (D5 isomer) are predominantly detected.

The digestion gas stored in the digestion gas tank 24 is introduced into the dehumidification cooler 1 using cold water (cooling medium), and most of the siloxane compounds in the digestion gas are condensed and separated together with water.

Subsequently, the digestion gas containing a small amount of the siloxane compound is introduced into the packed bed 11 filled with a porous adsorbent for adsorbing the siloxane compound. Here, the siloxane compound slightly remaining in the digested gas is adsorbed and removed by the porous adsorbent.

The dehumidifying cooler 1 and the packed bed 11 as described above
With this, the digestion gas purification apparatus of the present invention is constituted, and the digestion gas purified in this way is supplied to the communicating gas engine 2.
5 is introduced. Note that the gas engine 25 is an example of a power generation facility, and may be another power generation facility such as a gas turbine or a combustion boiler.

Exhaust gas that has undergone a combustion process in the gas engine 25 is introduced into a denitration catalyst tower 26, where nitrogen compounds in the exhaust gas are removed and then released to the atmosphere through a chimney (not shown). The denitration catalyst tower 26 is usually installed after the power generation equipment, but may be omitted if the nitrogen oxide concentration is low due to lean combustion or other contrivances. The material of the catalyst to be filled is not particularly limited as long as it is a catalyst used for denitration, and for example, a honeycomb shape or the like can be used.

The booster (gas compressor), not shown, may be located at any location on the upstream side of the gas engine 25, and may be appropriately installed. For example, between the packed bed 11 and the gas engine 25 or the dehumidifying cooler 1
And the filling layer 11. Alternatively, the booster may be omitted in the case of the low-pressure gas engine 25.

FIG. 5 shows the configuration of a conventional sewage sludge digestion gas power generation system. As shown, in the conventional sewage sludge digestion gas power generation system, the dehumidifying cooler 11
The digestion gas is directly introduced into the gas engine 25 from the digestion gas tank 24 because the gas filling layer 11 is not provided. For this reason, the inconvenience caused by the siloxane compound contained in the digestion gas as described above cannot be avoided.

Next, an example of the dehumidifying cooler 1 that can be used in the present invention will be described with reference to FIG.

A digestion gas at, for example, 40 ° C. from a digestion gas tank or the like is introduced into a dehumidifying cooler 1 via a digestion gas introduction pipe 2, and the digestion gas is indirectly subjected to heat exchange in a process of contacting the cooling pipe 4. And cooled to, for example, about 10 ° C. or less.

As the dehumidifying cooler 1, a known gas cooler capable of cooling a digestive gas to a temperature of, for example, about 10 ° C. or lower may be used. In particular, chillers, gas coolers, dehumidifiers, drain separators, etc. Various named devices can be used. However, a structure capable of discharging condensed water and the siloxane compound is required. Although the example shown in FIG. 2 is a type in which a cooling pipe is inserted into the inside of the apparatus to perform indirect heat exchange, a cooling mechanism may be provided on the outer wall of the apparatus to perform cooling by indirect heat exchange.

In the cooling pipe 4, for example, cold water of 10 ° C. or less is used as a cooling medium, and cold water is circulated and transferred by a cooling water supply device 5 including a tank, a pump, a flow meter, and a circulating water cooler (chiller). Is done. The siloxane compound cooled in the process of contact with the cooling pipe 4 and condensed together with the moisture in the digestion gas flows down to the lower part of the device and is temporarily stored.
It is transferred to a circulating water tank through a drain pipe. The digested gas from which the siloxane compound and the moisture have been separated is introduced into the next process device via the digested gas discharge pipe 3.

In FIG. 2, the cooling pipes 4 are schematically shown, but the present invention is not limited to this, and a plurality of cooling pipes may be connected vertically. Alternatively, the cooling pipe may be a flat cooling pipe instead of a cylindrical pipe, and may have any structure capable of indirectly exchanging heat with the cooling medium to cool the digestion gas. Also, to improve the efficiency of indirect heat exchange,
Partition plates may be alternately installed inside the main body 1 to secure a long gas passage.

The water and the siloxane compound condensed in the main body 1 are stored in a condensed water tank 7 through a drain pipe 6. Since many siloxane compounds are insoluble in water and have a specific gravity of 1.0 or less, they can be recovered as a supernatant. Alternatively, they can be separated and processed separately according to the specific gravity difference.

FIG. 3 shows another example of a dehumidifying cooler usable in the present invention. However, in FIG. 3, description of the same parts as in FIG. 2 will be omitted.

The digestion gas introduced by the digestion gas pipe 2 passes through a plurality of cooling pipes 4 (digestion gas flow passages) and is discharged from the digestion gas discharge pipe 3 at the lower part of the apparatus 1. For example, 10
Cooling water at a temperature of not more than 0 ° C. is continuously fed, filled and circulated into the inside of the device 1 by the cooling water supply device 5 via the water pipe 8. The outside of the cooling pipe 4 is configured such that cold water as a cooling medium comes into contact with the inside and the digestion gas flows inside the inside. In this process, the digestion gas is indirectly heat-exchanged to a temperature of about 10 ° C. or lower, and the moisture and the siloxane compound condense on the inner wall of the cooling pipe 4 or the lower part of the apparatus, and intermittently enter the condensed water tank via the discharge pipe 6. It is discharged to 7.

As described above, the digestion gas is purified by indirectly cooling with the cooling medium and condensing and separating the siloxane compound in the digestion gas with moisture. Therefore, silica (SiO ₂ ) derived from a siloxane compound is not deposited in a power generation facility such as a gas engine or a denitration facility in the latter stage. For this reason, it is possible to avoid abrasion and deterioration of the engine parts as in the related art. Further, the problem of deterioration of the denitration catalyst tower catalyst can be avoided beforehand because the siloxane compound in the gas has been removed. As a result, the frequency of maintenance and inspection of the power generation equipment and the denitration catalyst tower and the frequency of catalyst replacement can be significantly reduced.

When the digestion gas is cooled indirectly, the digestion gas is passed through a packed bed filled with a porous adsorbent to remove siloxane compounds in the digestion gas. Since the adsorption load can be significantly reduced, the life of the porous adsorbent can be extended.

In the dehumidifying cooler shown in FIGS. 2 and 3 as described above, the cooling medium to be introduced is preferably cold water of 10 ° C. or less.

By using cold water of 10 ° C. or less as a cooling medium for indirect cooling, the siloxane compound can be separated from the digested gas by an inexpensive and simple method without using, for example, a chlorofluorocarbon-based cooling medium that adversely affects the atmospheric environment. be able to. Further, the cooling temperature of the digested gas, that is, the siloxane compound is reduced to about 10 ° C.
Therefore, even when the concentration of the siloxane compound is relatively low, the condensation efficiency can be increased because of the low temperature.

It is desirable to determine the temperature of the chilled water as the cooling medium, the digested gas residence time in the dehumidifying cooler, and the heat transfer area (cooling pipe area) so that the cooling temperature of the digested gas is 10 ° C. or less. This is because, even if cold water of 10 ° C. or less is used as the cooling medium, if the contact time is short, the desired cooling temperature and the desired condensation effect are hardly achieved. However, even if the digestion gas is not cooled to 10 ° C. or less, if the surface (cold water) of the cooling pipe 4 is at a low temperature, the moisture and the siloxane compound aggregate on the surface of the cooling pipe 4 to remove them. This is not always the case because it can be separated.

Next, the digestion gas purifying apparatus of the present invention will be described with reference to FIG. FIG. 4 is a schematic diagram illustrating an example of the digestion gas purification apparatus of the present invention in which a packed bed containing a porous adsorbent is installed at a stage subsequent to the dehumidifying cooler. In FIG. 4, the description of the same components as those in FIG. 2 is omitted.

The digestion gas discharged from the dehumidifying cooler 1 is
The gas is introduced into the packed bed 11 through the digestion gas introduction pipe 12.
The packed bed 11 is filled with, for example, granular activated carbon as the porous adsorbent 14. When the digestion gas passes through the packed bed, the siloxane compound slightly remaining in the digestion gas is adsorbed and removed by the porous adsorbent, and the digestion gas is sufficiently purified. The digested gas thus purified is introduced into another process device such as a gas engine through the digested gas discharge pipe 13.

The packed bed 11 used in the digestion gas purifying apparatus of the present invention may be of a closed type which can be filled with a porous adsorbent and allows the gas to be treated to flow. Not limited. The superficial velocity of the digestion gas introduced into the packed bed 11 also depends on the filling amount of the porous adsorbent, but in order to obtain a sufficient contact efficiency between the gas and the adsorbent, for example, 0.5 m / s or less. It is preferable that

As the porous adsorbent to be filled in the filling layer 11, for example, the integrated capacity of pores having a specific surface area of at least 500 m ² / g and / or a pore diameter in the range of 10 to 20 ° is 0.1 mm. It is preferable to have a pore distribution of 1 cm ³ / g or more, but it is only necessary to have properties according to this. The material of the porous filler is not particularly limited, for example,
Activated carbon, zeolite, alumina, molecular sieves,
Other materials can be used. Such an adsorbent is subjected to a regenerating treatment by a heat swing method by heating, a pressure swing method by depressurization, or a combination thereof as necessary, and is repeatedly used.

A drain pipe for discharging drain (condensed water) generated when the apparatus is started up or shut down in the apparatus is installed below the packed bed 11 if necessary. It joins with the condensed water tank 7 attached to the wet cooler 1.
However, the present invention is not limited to this, and the drain may be separately treated.

If necessary, a filter (not shown) may be provided in the upper part of the apparatus in order to prevent the porous adsorbent 14 filled in the filling layer 11 from scattering. Alternatively, scattering of the porous adsorbent can be prevented by disposing a filter device at a later stage.

Further, if necessary, a drain separator (not shown) may be provided before and / or after the dehumidifying cooler 1 for auxiliary removal of water in the digestion gas. The drain separator is a device configured such that, for example, one or more collision plates are installed in a vertical direction to cause gas to collide, and mist in the gas is removed by inertia force or the like. In this case, the digestion gas is not cooled, but may be discharged together with the siloxane compound in the process of collecting mist (moisture). Therefore, the wastewater discharged from this device is introduced into the condensed water tank 7. It is desired to be configured so that The following effects can be obtained by installing the drain separator before and / or after the dehumidifying cooler 1. For example, when the dehumidifying cooler 1 is installed before, the mist (moisture) in the digestion gas is roughly removed, so that the load on the dehumidifying cooler 1 can be reduced. In this case, the amount of water entrained in the gas engine 25 can be reduced more safely.

The booster (gas compressor) for pressurizing the digestion gas introduced into the gas engine 25 at the subsequent stage is not shown, but the installation position is, as described above, any position upstream of the gas engine 25. Well, packed bed 11
And the gas engine 25 or between the dehumidifying cooler 1 and the packed bed 11. Alternatively, in the case of the low-pressure gas engine 25, the booster may be omitted. However, in order to avoid a rise in the pressure inside the dehumidifying cooler 1 and to obtain a desired siloxane compound separation efficiency, it is desirable to install the dehumidifying cooler 1 at a subsequent stage.

As described above, after the indirect cooling by the cooling medium is performed, the digestion gas is circulated through the packed bed filled with the porous adsorbent to adsorb and remove the siloxane compound, thereby completely removing the siloxane compound during the previous indirect cooling. Even if the siloxane compound that cannot be separated into the gas remains in the digested gas, the digested gas can be sufficiently purified by adsorbing and removing the siloxane gas. Therefore, it is possible to further reduce the frequency of maintenance and inspection of the power generation equipment such as a gas engine and the denitration equipment and the frequency of catalyst replacement in the latter stage.

In the digestion gas purification apparatus of the present invention provided with a dehumidification cooler and a packed bed, the siloxane compound contained in the digestion gas is separated and removed by indirect cooling by the dehumidification cooler, and the siloxane compound is contained in the digestion gas. Since the siloxane compound slightly remaining is adsorbed and removed by the packed bed, the amount of the siloxane compound flowing out in the subsequent stage can be surely reduced or set to zero. Therefore, silica (SiO ₂ ) derived from a siloxane compound is not deposited in a power generation facility such as a gas engine or a denitration facility in a subsequent stage. For this reason, it is possible to avoid abrasion and deterioration of the engine parts as in the related art. Further, the problem of deterioration of the denitration catalyst tower catalyst can be more reliably avoided by removing the siloxane compound in the gas.

[0053]

As described above, according to the present invention, there is provided an apparatus for purifying digested gas capable of efficiently and inexpensively removing siloxane compounds in sewage sludge digested gas.

When the present invention is applied to a sewage sludge digested gas power generation facility, the digested gas is purified by indirect cooling with a cooling medium to condense and separate the siloxane compound in the digested gas with moisture and separate it. Further, silica (SiO ₂ ) derived from a siloxane compound is not deposited in a power generation facility such as a gas engine or a denitration facility in a subsequent stage.
For this reason, it is possible to avoid abrasion and deterioration of the engine parts as in the related art. Further, the problem of deterioration of the denitration catalyst tower catalyst can be avoided beforehand because the siloxane compound in the gas has been removed. As a result, the frequency of maintenance and inspection of the gas engine and the frequency of replacement of the catalyst in the denitration catalyst tower can be significantly reduced.

The cooling medium for indirect cooling is 10 ° C.
By using the following cold water, the siloxane compound can be separated from the digested gas by an inexpensive and simple method without using, for example, a chlorofluorocarbon-based cooling medium that adversely affects the air environment. Furthermore, since the cooling temperature of the digestive gas, that is, the siloxane compound can be reduced to approximately 10 ° C. or less by setting the temperature of the cold water to 10 ° C. or less, even if the concentration of the siloxane compound is relatively low, the temperature is low. The condensation efficiency can be increased.

Further, after indirect cooling with a cooling medium, the digestion gas is passed through the packed bed filled with the porous adsorbent to adsorb and remove the siloxane compound, thereby completely separating the siloxane compound during the previous indirect cooling. Even when a siloxane compound that cannot be formed remains in the digested gas, the digested gas can be sufficiently purified by adsorbing and removing the siloxane gas. Therefore, it is possible to further reduce the frequency of maintenance and inspection of the power generation equipment such as a gas engine and the denitration equipment and the frequency of catalyst replacement in the latter stage.

In the digestion gas purifying apparatus of the present invention having the dehumidification cooler and the packed bed, the siloxane compound contained in the digestion gas is separated and removed by indirect cooling by the dehumidification cooler, and the siloxane compound is contained in the digestion gas. Since the siloxane compound slightly remaining is adsorbed and removed by the packed bed, the amount of the siloxane compound flowing out in the subsequent stage can be surely reduced or set to zero. Therefore, silica (SiO ₂ ) derived from a siloxane compound is not deposited in a power generation facility such as a gas engine or a denitration facility in a subsequent stage. For this reason, it is possible to avoid abrasion and deterioration of the engine parts as in the related art. Further, the problem of deterioration of the denitration catalyst tower catalyst can be more reliably avoided by removing the siloxane compound in the gas.

By using the present invention, not only sewage sludge digestion gas but also siloxane compounds can be easily and efficiently removed from siloxane compound-containing gases such as various factory exhaust gases handling organic silicon and air conditioning exhaust gases. , Its industrial value is great.

[Brief description of the drawings]

FIG. 1 is a schematic diagram showing a configuration of an example of a sewage sludge digestion gas power generation system including a digestion gas purification device according to the present invention.

FIG. 2 is a schematic diagram illustrating a configuration of an example of a dehumidifying cooler that can be used in the present invention.

FIG. 3 is a schematic diagram illustrating a configuration of another example of a dehumidification cooler that can be used in the present invention.

FIG. 4 is a schematic diagram illustrating an example of a digestion gas purification device of the present invention.

FIG. 5 is a schematic diagram showing a configuration of a conventional sewage sludge digestion gas power generation system.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 ... Dehumidification cooler 2 ... Digestion gas introduction pipe 3 ... Digestion gas discharge pipe 4 ... Cooling pipe 5 ... Cooling water supply device (chiller) 6 ... Drainage pipe 7 ... Condensed water tank 8 ... Water supply pipe 11 ... Packing layer 12 ... Digestion gas introduction pipe 13 ... Digestion gas discharge pipe 14 ... Porous adsorbent 24 ... Digestion gas tank 25 ... Gas engine (power generation equipment) 26 ... Denitration catalyst tower

 ──────────────────────────────────────────────────続 き Continuing on the front page (72) Inventor Akira Shimizu 1-2-1, Marunouchi, Chiyoda-ku, Tokyo Nihon Kokan Co., Ltd. (72) Inventor Hiroshi Shimizu 1-2-1, Marunouchi, Chiyoda-ku, Tokyo Sun F-term in Honko Co., Ltd. (reference) 4D052 AA02 BA03 GA04 GB06

Claims (4)

[Claims] 1. A method for removing said siloxane compound from sewage sludge digestion gas containing a siloxane compound, wherein said digestion gas is indirectly cooled by exchanging heat with a cooling medium,
A digestion gas refining method, comprising a step of separating the siloxane compound from the digestion gas by condensing the siloxane compound contained in the digestion gas with moisture. 2. The digestion gas purification method according to claim 1, wherein the cooling medium is cold water of 10 ° C. or lower. 3. The digestion gas from which the siloxane compound has been separated by the indirect cooling is passed through a packed bed filled with a porous adsorbent, and the siloxane compound in the siloxane compound-containing gas is passed through the porous adsorbent. The digestion gas purification method according to claim 1 or 2, further comprising a step of removing a siloxane compound remaining in the gas by causing the gas to adsorb. 4. An apparatus for removing said siloxane compound from sewage sludge digestion gas containing a siloxane compound, wherein said digestion gas is indirectly cooled by heat exchange with a cooling medium,
A dehumidification cooler that condenses the siloxane compound contained in the digestion gas together with moisture; and a porous adsorbent that is installed at a stage subsequent to the dehumidification cooler and adsorbs and removes the siloxane compound remaining in the digestion gas. A digestion gas purifying apparatus, comprising: a packed bed filled with the digested gas.