JP2005046755A - Gas cleaning method and gas cleaning device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a gas cleaning method capable of simply removing dimethylsiloxane from a material gas containing dimethylsiloxane for a long period of time, and a gas cleaning device. <P>SOLUTION: In (1) the gas cleaning method, the temperature of the material gas containing dimethylsiloxane is measured and after the material gas is heated such that the temperature becomes a temperature higher than the temperature by 2°C and not more than 50°C, it is introduced to an activated carbon filling layer 2 to remove dimethylsiloxane from the material gas. Further, (2) in the gas cleaning method, an activated carbon having fine pores with an average fine pore diameter of 2.0-4.0 nm is used as the activated carbon in the gas cleaning method. (3) The gas cleaning device is provided with a detection part for measuring the temperature of the material gas containing dimethylsiloxane; a previously heating part for heating the material gas based on the temperature measured by the detection part; and the activated carbon filling layer 2. In the gas cleaning device, the material gas heated by the previously heating part is introduced to the activated carbon filling layer 2 to remove dimethylsiloxane from the material gas. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention belongs to a technical field related to a gas purification method and a gas purification apparatus, and in particular, removes dimethylsiloxane from methane-containing gas generated when anaerobic fermentation of organic waste such as garbage and sewage sludge is performed. The present invention belongs to a technical field related to a gas purification method and a gas purification apparatus.

  As is well known, methane-containing gas is generated when anaerobic fermentation of organic waste such as garbage and sewage sludge. Utilization of the methane-containing gas generated in this way as a fuel for power generation is being actively promoted in Western countries, particularly in Germany. However, such a methane-containing gas contains a substance as described later, and there is an urgent need to realize means for economically removing this substance.

That is, it is known that a methane-containing gas generated in sewage sludge or the like contains a trace amount of an organic silicon compound generated by decomposition of shampoo or rinse. Among these organosilicon compounds, a dimethylsiloxane cyclic organic compound (hereinafter referred to as dimethylsiloxane) having a unit structure of —Si (CH ₃ ) ₂ O— and having three or more unit structures bonded to each other is methane-containing. It is known to cause major obstacles when using gas.

Dimethylsiloxane contained in such a methane-containing gas (raw gas) has a low concentration of about 100 mg / m ³ or less. However, for example, when the methane-containing gas containing dimethylsiloxane is used as a fuel to drive a gas engine to generate electric power, the dimethylsiloxane changes to solid SiO ₂ in the gas engine. As a result, damage to the gas engine (ignition failure due to sticking to the spark plug, premature wear of the cylinder liner and piston, SiO ₂ sticking to the entire intake valve, exhaust valve and engine combustion chamber head) occurred, resulting in the gas engine Long-term driving becomes difficult. The reason why dimethylsiloxane changes to solid SiO ₂ in the gas engine is that SiO ₂ remains due to the combustion disappearance of the organic part (methyl group) of dimethyl siloxane in the gas engine, and the remaining SiO ₂ remains in the gas engine. It is thought that it is to grow gradually. Similar troubles are also expected to occur in other internal combustion engines such as gas turbines.

  In order to avoid the above-mentioned problems caused by dimethyl siloxane and to achieve a long-term stable operation of an internal combustion engine such as a gas engine, various methods for removing dimethyl siloxane are proposed as follows. .

(A) Method of adsorbing and removing dimethylsiloxane with an adsorbent such as activated carbon
(B) A method of absorbing and removing dimethylsiloxane with a solvent rich in absorption capacity
(C) Method of cooling methane-containing gas (raw gas) to about -30 ° C and solidifying and separating dimethylsiloxane

As a specific example of the method for removing dimethylsiloxane using the adsorbent (A), a method for removing dimethylsiloxane using activated carbon is, for example, “The 38th Lecture on Sewerage Research Presentation, 695” (non-patent document). Document 1). The method for removing dimethylsiloxane using activated carbon (hereinafter also referred to as a conventional example) is as follows. By supplying activated carbon with a sewage digestion gas under conditions of a filling height of activated carbon of 0.3 m and a gas superficial velocity of 0.15 m / s, The removal performance of activated carbon for dimethylsiloxane was investigated. In this case, the dimethylsiloxane removal rate from sewage digestion gas is maintained at 90% or more until 550 hours, and it is said that dimethylsiloxane can be removed from sewage digestion gas.
The 38th Sewerage Research Presentation Lecture, 695 pages

  In general, in the case of the removal method by adsorption using activated carbon, as shown in Fig. 1, normal activated carbon suddenly increases the moisture adsorption amount from about 60%, and the adsorption performance decreases accordingly. There is a problem of end up. Since the methane-containing gas generated by anaerobic fermentation has a relative humidity of nearly 100%, the relative humidity should be adjusted in advance (before being introduced into the activated carbon packed bed) so that the relative humidity is about 50%. It is considered that a process for lowering is required.

As a method for reducing the relative humidity of the gas, the following method is generally used.
(1) Once the gas is cooled, the water is condensed and removed, and then reheated.
(2) Adsorb and remove moisture using a hygroscopic agent.
(3) Heat the gas.

  However, in the method (1), since cooling and heating are performed, energy is required, and in addition, treatment of condensed water is required. The method (2) has a drawback that it is necessary to provide a hygroscopic regeneration mechanism and that the hygroscopic agent deteriorates immediately upon receiving poisoning such as siloxane.

  The method (3) by heating is the simplest method, but there are restrictions on the heating temperature. That is, the temperature of the methane-containing gas generated by anaerobic fermentation is about 40 ° C. On the other hand, when the raw gas temperature increases, the gas engine has a lower thermal efficiency and cannot be applied at a temperature higher than 50 ° C. In order to bring the raw gas at a temperature of 40 ° C and a relative humidity of 100% to a relative humidity of 50% or less, it is necessary to heat it to a temperature above 50 ° C. Therefore, it is necessary to provide a mechanism for cooling the gas at the subsequent stage of the purification apparatus, or to cool and dehumidify the gas at the previous stage of the purification apparatus and then return to the original temperature. Moreover, since the power generation efficiency of the gas engine decreases as the intake air temperature rises, it is desirable that the heating temperature be as low as possible.

  In the conventional example (method for removing dimethylsiloxane by activated carbon described in Non-Patent Document 1), dimethylsiloxane can be removed for up to 550 hours, but it is considered difficult to remove dimethylsiloxane. It is done. In other words, the processing conditions in the above-mentioned conventional example are that the gas space velocity (SV) is 1800 m / h, and it is determined that the adsorption apparatus (adsorption tower) is a standard or a slightly larger scale with respect to the amount of gas to be processed. . Nevertheless, the adsorbent (activated carbon) used in this adsorption device has a short endurance time (removable time of dimethylsiloxane), so it is considered that frequent replacement of the activated carbon is necessary and is an economical means. Is a bad thing. In order to cope with the problem of durability in such an adsorption device according to the conventional example, there is no measure other than increasing the filling amount of activated carbon, and as a result, it is impossible to avoid an increase in the size of the adsorption device.

  The present invention has been made paying attention to such circumstances, and an object thereof is to provide a gas purification method and a gas purification apparatus capable of easily removing dimethylsiloxane from a raw gas containing dimethylsiloxane over a long period of time. It is something to try.

  In order to achieve the above object, the present inventors have intensively studied, and as a result, completed the present invention. According to the present invention, the above object can be achieved.

  The present invention, which has been completed in this way and has achieved the above object, relates to a gas purification method and a gas purification apparatus, and relates to a gas purification method according to claims 1 to 4 (first to fourth inventions). The gas purification apparatus according to claim 5, which is configured as follows.

  That is, in the gas purification method according to claim 1, the temperature of the raw gas containing dimethylsiloxane is measured, and the raw gas is adjusted to a temperature that is 2 ° C. or higher and 50 ° C. or lower from the measured temperature. Is a gas purification method characterized by removing dimethylsiloxane from the raw gas after being heated into an adsorption part filled with activated carbon [first invention].

  The gas purification method according to claim 2 is the gas purification method according to claim 1, wherein activated carbon having pores having an average pore diameter of 2.0 to 4.0 nm is used as the activated carbon [second invention].

  The gas purification method according to claim 3 is the gas purification method according to claim 1 or 2, wherein the volume of pores of 1.0 nm or less of the activated carbon is 0.2 ml / g or less [third invention].

  The gas purification method according to claim 4 is the gas purification method according to any one of claims 1 to 4, wherein the raw gas is a methane-containing gas generated from organic waste by anaerobic fermentation. invention〕.

  The gas purifier according to claim 5 is filled with activated carbon, a detector that measures the temperature of the raw gas containing dimethylsiloxane, a preheater that heats the raw gas based on the temperature measured by the detector. A gas refining apparatus comprising: a raw gas heated by the preheating unit and removing dimethylsiloxane from the raw gas [fifth invention].

  According to the gas purification method of the present invention, dimethylsiloxane can be easily removed from a raw gas containing dimethylsiloxane over a long period of time.

  The gas purification apparatus according to the present invention can perform a gas purification method that can easily remove dimethylsiloxane from a raw gas containing dimethylsiloxane over a long period of time.

  As described above, the methane-containing gas generated by anaerobic fermentation has a relative humidity of almost 100%. Therefore, the methane-containing gas is introduced in advance into the activated carbon packed bed so that the relative humidity becomes about 50%. It was thought that it was necessary to reduce the relative humidity. Further, as described above, it is necessary to heat the raw gas having a temperature of 40 ° C. and a relative humidity of 100% to a temperature exceeding 50 ° C. in order to make the relative humidity 50% or less.

  However, the present inventors have conducted various studies on techniques for removing dimethylsiloxane from raw gas (containing dimethylsiloxane) such as the above methane-containing gas using activated carbon. Unlike the idea described above, when the raw gas is a raw gas containing dimethylsiloxane, it is not always necessary to lower the relative humidity of the raw gas to about 50%, and it may be reduced to about 90% or less. In order to achieve this, it has been found that the raw gas may be heated to a temperature 2 ° C. higher than that temperature. For example, it has been found that in the case of a raw gas having a temperature of 40 ° C. and a relative humidity of 100%, it may be heated to 42 ° C. or higher.

  Thus, when the raw gas is a raw gas containing dimethylsiloxane, the raw gas may be heated to a temperature 2 ° C. higher than that temperature, thereby reducing the adsorption performance of the activated carbon over a long period of time. This can prevent the activated carbon from increasing the durability time (removable time of dimethylsiloxane), and thus remove dimethylsiloxane from the raw gas (containing dimethylsiloxane) over a long period of time. However, on the other hand, the raw gas after the removal of dimethylsiloxane is desirably 50 ° C. or less because of its availability, and as described above, when used as a fuel for power generation of a gas engine, from the viewpoint of thermal efficiency. It is necessary that the temperature is 50 ° C. or lower. From the viewpoint of power generation efficiency, it is desirable that the temperature is 50 ° C. or lower.

  Therefore, the gas purification method according to the present invention measures the temperature of the raw gas containing dimethylsiloxane, and supplies the raw gas so that the temperature becomes 2 ° C. or higher and 50 ° C. or lower from the measured temperature. After heating, the gas purification method is characterized in that it is introduced into an adsorption section filled with activated carbon to remove dimethylsiloxane from the raw gas [first invention]. According to this gas purification method, as can be seen from the above, dimethylsiloxane can be removed over a long period of time from the raw gas containing dimethylsiloxane. In addition, this gas purification method uses a simple heating method as a method for reducing the relative humidity of the raw gas, and at the time of heating, the temperature is only 2 ° C. higher than the temperature of the raw gas and is 50 ° C. or lower. Since it is a grade which heats, it is very simple. The temperature that is 2 ° C. or higher and 50 ° C. or lower from the measured temperature is a temperature that is 2 ° C. or higher and 50 ° C. or lower from the measured temperature. That is, if the measured temperature is T ° C., the temperature is (T + 2) ° C. to 50 ° C. (including 50 ° C.). For example, when the measured temperature is 40 ° C., it is 42 ° C. to 50 ° C.

  At this time, if activated carbon having pores having an average diameter (average pore diameter) of 2.0 to 4.0 nm is used as the activated carbon, the adsorption performance and durability (removable time of dimethylsiloxane) are improved at a higher level. The dimethylsiloxane can be removed more reliably (at a high level) over a long period of time [second invention]. Details will be described below.

  The present inventors pay attention to activated carbon, and eagerly researched to realize activated carbon having both excellent adsorption performance and durability (removable time of dimethylsiloxane) under high humidity conditions with respect to dimethylsiloxane. Piled up. As a result, the activated carbon having pores with an average pore diameter of 2.0 to 4.0 nm is particularly excellent by heating raw gas such as methane-containing gas (containing dimethylsiloxane) at 2 ° C or higher, preferably 3 ° C or higher. It has been found that it has performance and durability.

Dimethylsiloxane contained in sewage digestion gas is known to have 3 to 6 unit structures of —Si (CH ₃ ) ₂ O—, and the molecular size of the unit structure is 0.7 to 1.1. Estimated to be nm. On the other hand, since the average pore diameter of the activated carbon pores is usually 1.Onm or more, activated carbon having pores with smaller average pore diameters is considered preferable. However, when the volume of the pores that greatly affects the durability is about the same, the average pore diameter is 2.0 to 4.Onm, which is a relatively large fine particle than the activated carbon with many pores with an average pore diameter of 2.Onm or less. It was found that the activated carbon having pores has a larger adsorption performance for dimethylsiloxane.

  That is, it has been found that activated carbon used for solvent recovery or the like is preferable for adsorption of dimethylsiloxane, as compared with the activated carbon for gas treatment used for general deodorization and the like. This is presumably because several molecules of dimethylsiloxane are condensed and trapped in the pores when dimethylsiloxane is adsorbed on the activated carbon. However, it has been found that activated carbon having pores with an average pore diameter exceeding 4.Onm cannot provide sufficient dimethylsiloxane removal performance.

  It was also found that activated carbon having pores with an average pore diameter of 3.5 nm or less has the best dimethylsiloxane removal performance.

  Therefore, when activated carbon having pores with an average pore diameter of 2.0 to 4.0 nm is used as the activated carbon in the above-described gas purification method [first invention] according to the present invention, the adsorption performance and durability (removable time of dimethylsiloxane) And dimethylsiloxane can be removed more reliably (at a high level) over a long period of time [second invention]. Further, among these activated carbons, the use of activated carbon having pores with an average pore diameter of 3.5 nm or less can increase the performance of removing dimethylsiloxane. The average pore diameter is determined by the following method, for example. The pore volume is determined from the volume of molecules adsorbed at a certain pressure. From the relationship between the pressure and the amount of adsorption, the pore surface area is obtained using a certain conversion formula (BET formula). From these, the volume of all pores is calculated by dividing by the pore surface area. The activated carbon having pores having an average pore diameter of 2.0 to 4.0 nm is activated carbon having an average pore diameter of 2.0 to 4.0 nm.

By the way, when the pore diameter of activated carbon is 1.0 nm or less, flammable substances such as H ₂ and CH ₄ and flammable substances such as O ₂ are adsorbed, which may increase the ignition risk of activated carbon. There is sex. On the other hand, in the case of activated carbon having pores with an average pore diameter of 2.0 to 4.0 nm, there are few pores with small pore diameters, so that a combustible substance such as H ₂ or CH ₄ or O ₂ is supported. The adsorbed amount of the flammable substance is small, and therefore, there is an effect that the ignition risk of the activated carbon is reduced and the activated carbon is easily handled.

  In order to reduce the ignition risk of such activated carbon, it is desirable that the volume of pores of 1.0 nm or less of the activated carbon is 0.2 ml / g or less [third invention].

Incidentally, an example in which the amount of adsorption of H ₂ that increases the risk of ignition increases when there are many pores of 1.Onm or less is shown below. In this example, the adsorption amount of H ₂ was investigated under the temperature and pressure conditions of 23 ° C and 1MPa using activated carbon with the same average pore diameter and different 1.Onm pore volume. It is. With activated carbon A having an average pore diameter of 2.13 nm and a volume of pores of 1.Onm or less of 0.15 ml / g, the adsorption amount of H ₂ was 0.18 (mol-H ₂ / kg-activated carbon). In contrast, activated carbon B with an average pore diameter of 2.06 nm and a pore volume of 1.Onm or less of 0.23 ml / g has an H ₂ adsorption of 0.33 (mol-H ₂ / kg-activated carbon). Yes, this activated carbon B has a larger amount of adsorption of H ₂ than activated carbon A. In addition, mol-H ₂ / kg-activated carbon is the adsorption amount (mol) of H ₂ per 1 kg of activated carbon.

  Regarding the activated carbon having pores with an average pore diameter of 2.0 to 4.0 nm (hereinafter also referred to as activated carbon according to the second invention), the influence of relative humidity on the adsorption performance was examined. As a result, it was found that benzene had a significant effect when the relative humidity was about 40%, whereas dimethylsiloxane had a small effect when the relative humidity was 90%. Dimethylsiloxane is a highly hydrophobic substance, and is considered to have a high affinity with activated carbon having a high hydrophobicity. It is estimated that the activated carbon having a large pore diameter (activated carbon according to the second invention) is not easily affected by water adsorption because water condenses from pores having a small diameter when the humidity increases.

  By using activated carbon that is not easily affected by relative humidity in this way, sufficient removal performance can be exhibited only by heating the raw gas at 2 ° C. or higher.

  In the present invention, the raw gas containing dimethylsiloxane is not particularly limited, and examples thereof include methane-containing gas generated from organic waste by anaerobic fermentation [fourth invention].

  A gas purification apparatus according to the present invention is filled with a detection unit that measures the temperature of a raw gas containing dimethylsiloxane, a preheating unit that heats the raw gas based on the temperature measured by the detection unit, and activated carbon. The gas purifier is characterized in that the raw gas heated in the preheating part is introduced into the adsorption part to remove dimethylsiloxane from the raw gas [fifth invention]. According to this gas purification apparatus, the temperature of the raw gas (containing dimethylsiloxane) is measured at the detection unit, and the temperature is 2 ° C. or higher and 50 ° C. or lower from the measured temperature at the preheating unit. After heating the raw gas, it can be introduced into the adsorption section to remove dimethylsiloxane from the raw gas. That is, the gas purification method according to the present invention can be performed, and according to this gas purification method, dimethylsiloxane can be easily removed from the raw gas (containing dimethylsiloxane) over a long period of time. That is, a gas purification method that can easily remove dimethylsiloxane from raw gas (containing dimethylsiloxane) over a long period of time can be performed. As a result, dimethylsiloxane can be easily removed over a long period of time.

  At this time, if activated carbon having an average pore diameter of 2.0 to 4.0 nm (activated carbon according to the second invention) is used as activated carbon, the adsorption performance and durability (removable time of dimethylsiloxane) are excellent at a higher level. Dimethylsiloxane can be removed more reliably (at a high level) over a longer period of time.

  In the present invention, the type of activated carbon is not particularly limited, and may be, for example, coconut shell type or coal type. Also, the shape and molding method of the activated carbon are not particularly limited, and any of pellets, granular crystals, crushed crystals, and extruded products may be used, and may be appropriately selected depending on the purpose of use. Is. The activated carbon according to the second invention is the same as described above. In this case, the average pore diameter (average pore diameter) needs to be 2.0 to 4.0 nm.

  In the present invention, when the raw gas is heated and then introduced into the adsorption section filled with activated carbon, the flow rate of the raw gas to be introduced is not particularly limited and may be appropriately selected according to the purpose of use. Is.

According to the present invention, a methane-containing gas having a low concentration of dimethylsiloxane can be obtained by dimethylsiloxane removal treatment. The methane-containing gas thus obtained can be used as a fuel by various methods. For example, an internal combustion engine such as a gas engine or a gas turbine can be stably driven over a long period of time to obtain heat and electricity, and can be stored in a cylinder to be used as a fuel for various applications such as automobiles. It is also possible. In other words, an optimal usage form may be selected as appropriate in consideration of the amount of gas obtained, usage, regional conditions, and the like. Furthermore, methane-containing gas is non-fossil fuel-based energy, so-called biomass energy, and its use of fuel is considered to be free of CO ₂ , so it is a preferred form of use as an energy source for a recycling society.

  Examples of the present invention will be described below. The present invention is not limited to this embodiment, and can be implemented with appropriate modifications within a range that can be adapted to the gist of the present invention, all of which are within the technical scope of the present invention. include.

[Example 1]
Dimethylsiloxane-containing gas was supplied to several types of activated carbons having pores with different average pore sizes, and the relationship between the average pore size and the removal performance of dimethylsiloxane was investigated. More specifically, the following tests were conducted.

  As the activated carbon, activated carbon having pores having an average pore diameter of 1.67 nm to 4.05 nm was used. These activated carbons are all 1/8 inch diameter extruded pellets, each having a specific surface area of 1000 to 1200 m / g and a pore volume of 0.50 to 0.60 ml / g. There is no big difference between them. In addition, the said average pore diameter is calculated | required by analyzing the measured value measured by the nitrogen gas adsorption method.

FIG. 2 shows a schematic diagram of a dimethylsiloxane adsorption test apparatus. In FIG. 2, reference numeral 1 is an adsorption tube having an inner diameter of 30 mm, and 2 is a packed bed having a height of 15 cm. As shown in FIG. 2, the above-mentioned activated carbon is filled in the adsorption tube 1 having an inner diameter of 30 mm to form a packed bed 2 having a height of 15 cm. Then, in the filling layer 2 airflow 10.6 normal liters / min, and supplying the simulated gas G ₁ was adjusted to the composition described below as dimethyl siloxane-containing gas. The air volume (10.6 normal liters / min) of the simulated gas G ₁ corresponds to a superficial space velocity (SV) of 6000 / h, and the gas supply rate per unit time and unit activated carbon volume is superficial space velocity (SV ) Is 1800 / h, which is about 3.3 times that of the conventional example (method for removing dimethylsiloxane by activated carbon described in Non-Patent Document 1).

The simulation gas G ₁ supplied to the packed bed 2 vaporizes each dimethylsiloxane in an amount corresponding to dimethylsiloxane tetramer (D4): 250 mg / Nm ³ , pentamer (D5): 250 mg / Nm ³ , This vaporized dimethylsiloxane has a composition prepared by mixing nitrogen gas so that the temperature is 30 ° C. and the relative humidity is 80%. That is, nitrogen gas is mixed with the vaporized dimethylsiloxane so that the temperature of the mixed gas is 30 ° C. and the relative humidity is 80%. The concentration of dimethyl siloxane, which is included in the simulated gas G ₁ is about 6 times the concentration of dimethyl siloxane contained in dimethylsiloxane-containing gas used in the prior art. The dimethylsiloxane tetramer (D4) has a molecular structure in which four dimethylsiloxane unit structures are bonded as shown in FIG.

  As described above, the test conditions in this example are that the gas supply amount per unit time and unit activated carbon volume is about 3.3 times that of the conventional example, and the concentration of dimethylsiloxane is about 6 times. When these are simply multiplied, it can be said that the evaluation of activated carbon is about 20 times more severe than the conventional example.

The removal performance of dimethylsiloxane by each activated carbon was examined by quantifying the concentrations of D4 and D5 at the outlet of the activated carbon every hour with a gas chromatograph. Immediately after the simulation gas G _{1 was} supplied, dimethylsiloxane could not be detected from the gas flowing out from the activated carbon outlet in any activated carbon.

  The result of the said test is shown to Tables 1-2. That is, Table 1 shows the average pore diameter of the pores of each activated carbon and the time when the dimethylsiloxane removal rate was reduced to 90% under the above test conditions. Table 2 shows changes in the dimethylsiloxane removal rate with respect to the treatment time (relationship between the treatment time and the removal rate) when No. 2 activated carbon (average pore diameter 2.09 nm) shown in Table 1 is used as the activated carbon. In addition, the removal rate of dimethylsiloxane is calculated by the following formula.

  Dimethylsiloxane removal rate (%) = [1- (sum of D4 and D5 concentrations in outlet gas) / (sum of supplied D4 and D5 concentrations)] × 100

  As can be seen from Table 1, in the case of activated carbon (No. 2 to 6) having pores with an average pore diameter of 2.09 to 3.73 nm, activated carbon having pores with average pore diameters of 1.67 nm and 4.05 nm ( Compared to the cases of No.1 and No.7), it takes a longer time until the removal rate of dimethyl siloxane is reduced to 90%. Also, as can be seen from Table 2, 100% dimethylcyclosan has been removed up to 27 hours. In addition, although the result of this Table 2 is a thing at the time of using No. 2 activated carbon as activated carbon, when using No. 3-6 activated carbon, it is the same as the case where No. 2 activated carbon is used. Show the trend. Accordingly, the durability of the activated carbons No. 2 to 6 (particularly the dimethylsiloxane removal time) is extremely excellent, and in particular, the activated carbon according to the second invention (having pores with an average pore diameter of 2.0 to 4.0 nm) It can be clearly seen that the activated carbon is extremely excellent in durability (time for removing dimethylsiloxane).

  As shown in Table 1, the activated carbons of Nos. 2 to 6 have a period of 29 to 44 hours until the removal rate of dimethyl siloxane is reduced to 90%. When converted into the concentration conditions of dimethylsiloxane and dimethylsiloxane, it corresponds to 580 to 880 hours, which exceeds 550 hours of the conventional example.

In the above test, the simulated gas G ₁ was used as the raw gas (containing dimethylsiloxane). As described above, the simulation gas G ₁ is obtained by mixing vaporized dimethylsiloxane with nitrogen gas so that the temperature is 30 ° C. and the relative humidity is 80%. As can be seen from Table 3 to be described later, this simulated gas G ₁ is obtained by raising the raw gas (temperature T ₁ ) having a relative humidity of approximately 100% to a temperature 2 to 3 ° C. higher than that temperature (ie, T ₁ +2 to T ₁ +3 [deg.] C.) and the raw gas is heated to a temperature of 50 [deg.] C. or lower. Therefore, any test corresponds to an example of the present invention.

  On the other hand, when a source gas (containing dimethylsiloxane) having a relative humidity of approximately 100% is used without adjusting the relative humidity, durability (time for removing dimethylsiloxane) decreases. That is, compared with such a case, in the case of the above-mentioned embodiment of the present invention, durability is excellent.

[Example 2]
As the activated carbon, the same activated carbon (average pore diameter 2.09 nm) as No. 2 shown in Table 1 was used. As the raw gas (containing dimethylsiloxane), a simulated gas G ₂ having a temperature of 40 ° C. and a relative humidity of 100% was used. Then, this was heated simulated gas G ₂ to 41 to 50 ° C., if a similar filling layer 2 Example 1 (however, activated carbon like activated carbon and No.2 shown in Table 1) Similar conditions The same test was conducted to examine the time for the dimethylsiloxane removal rate to drop to 90%. Further, the simulated gas G ₂ without heating (in the state of 40 ° C.) is supplied to the packed bed 2, the same test was carried out. Incidentally, upon heating of the simulated gas G _2, when heated to 42-50 ° C. will be to meet the heating temperature of the raw gas of the invention, corresponding to Example of the present invention.

The results of the above test are shown in Table 3. Since the absolute humidity is the same (water vapor pressure 7.4 kPa), the relative humidity decreases as the temperature increases. When the simulated gas G ₂ (temperature 40 ° C., relative humidity 100%) is supplied to the packed bed 2 without heating (at 40 ° C.), the time for the dimethylsiloxane removal rate to drop to 90% is 9 h. The shortest. When the simulated gas G ₂ is heated to 41 ° C. and heated to 1 ° C. higher than the original temperature and then supplied to the packed bed 2, the relative humidity of the gas is 95%, and the removal of dimethyl cyclosan The time until the rate drops to 90% is 14h, which is short.

On the other hand, when the simulated gas G ₂ is heated to 42 ° C. to a temperature 2 ° C. higher than the original temperature, the relative humidity of the gas becomes 90%. The time until the removal rate of sikylosan drops to 90% is 30 hours, which is significantly longer. Further, when the heating temperature of the simulated gas G ₂ is increased, the relative humidity of the gas is decreased, and the time until the dimethyl siloxane removal rate is reduced to 90% is increased. However, in the case of the results in Table 3, when the heating temperature of the simulated gas G ₂ is between 45 ° C. and 50 ° C., the time until the removal rate of dimethyl siloxane is reduced to 90% is almost the same.

In Example 2 above, activated carbon similar to No. 2 shown in Table 1 (average pore diameter 2.09 nm) was used as the activated carbon, but instead of this, other activated carbon such as No. 1 shown in Table 1 was used. Activated carbon (average pore size 2.45 to 3.73 nm) similar to 3-6, activated carbon similar to No. 7 (average pore size 4.05 nm), activated carbon similar to No. 1 (average pore size 1.67 nm) In this case, the same tendency result as in the case of Example 2 is obtained. That is, when the simulated gas G ₂ is heated to 42 ° C. to 50 ° C. to 2 ° C. to 10 ° C. higher than the original temperature and then supplied to the packed bed 2, the removal rate of dimethyl cyclosan is 90 The time to drop to% is significantly longer. However, the absolute value (h) of the time until the removal rate of dimethylcyclosan is reduced to 90% varies depending on the average pore diameter of the used activated carbon even under the condition that the heating temperature of the simulated gas G ₂ is the same.

  In Examples 1 and 2, a test apparatus in which activated carbon was packed in an adsorption tube having an inner diameter of 30 mm was used as the apparatus. However, even in the case where a practical-scale adsorption tower is used as the adsorption tube, Example 1 is used. It is possible to obtain the same effect as in the case of ~ 2.

  Since the gas purification method according to the present invention can easily remove dimethylsiloxane from raw gas containing dimethylsiloxane over a long period of time, it is generated when anaerobic fermentation of organic waste such as garbage and sewage sludge It can be suitably used as a method for removing dimethylsiloxane when a gas from which dimethylsiloxane has been removed from a methane-containing gas or the like used as a fuel for power generation of a gas engine or the like. In addition, the gas purification apparatus according to the present invention can be suitably used as an apparatus for performing the dimethylsiloxane removal method as described above.

It is a figure which shows the adsorption isotherm of water at 20 degreeC of activated carbon, Comprising: It is a figure which shows the relationship between the relative humidity of the gas of the adsorption processing object by activated carbon, and the moisture adsorption amount to activated carbon. It is a schematic diagram which shows the apparatus used for the dimethylsiloxane adsorption test based on an Example. It is a figure which shows the molecular structure of a dimethylsiloxane tetramer (D4).

Explanation of symbols

1—Adsorption tube, 2—Packed bed of activated carbon.

Claims (5)

  The temperature of the raw gas containing dimethylsiloxane is measured, and after heating the raw gas so that the temperature becomes 2 ° C. or higher and 50 ° C. or lower from the measured temperature, the adsorption section filled with activated carbon The gas purification method is characterized by introducing dimethylsiloxane from the raw gas.   The gas purification method according to claim 1, wherein activated carbon having pores having an average pore diameter of 2.0 to 4.0 nm is used as the activated carbon.   The gas purification method according to claim 1 or 2, wherein the volume of pores of 1.0 nm or less of the activated carbon is 0.2 ml / g or less.   The gas purification method according to any one of claims 1 to 4, wherein the raw gas is a methane-containing gas generated from organic waste by anaerobic fermentation.   A detector that measures the temperature of the raw gas containing dimethylsiloxane; a preheater that heats the raw gas based on the temperature measured by the detector; and an adsorber that is filled with activated carbon. A gas refining apparatus, wherein the raw gas heated in the section is introduced into the adsorption section to remove dimethylsiloxane from the raw gas.