JP3592648B2 - Method and apparatus for using digestive gas - Google Patents

Description

[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to a method for efficiently consuming digestive gas generated during biological treatment in a consuming facility and an apparatus therefor.
[0002]
[Prior art]
BACKGROUND ART Biological treatment of organic waste generated in sewage treatment plants, food factories, beer manufacturing factories, livestock breeding facilities, and the like generates digestive gas composed of methane, carbon dioxide, hydrogen sulfide, and the like. Such digestion gas is effectively used as an energy source by, for example, the following method.
That is, first, hydrogen sulfide contained in the generated digestive gas is removed by a desulfurization tower or the like, and then stored appropriately in a low-pressure gas holder, and then burned in a boiler or other consuming equipment. The heat generated at this time is sent to various facilities and used effectively.
[0003]
[Problems to be solved by the invention]
However, although the digestive gas is always generated, it is difficult to control the generation amount and the calorific value, and the digestive gas is generated even when the consuming equipment is not operating. Many gas utilization facilities use low-pressure gas holders, which are simple in structure and easy to maintain, to absorb the gap between gas generation and consumption. However, if this gap is to be absorbed only by the low-pressure gas holder, there is a problem that the storage capacity of the low-pressure gas holder that stores the gas at almost atmospheric pressure is very low, and the required capacity becomes huge. Therefore, the capacity of the low-pressure gas holder is usually suppressed to a certain size, and digestive gas that cannot be stored is treated as surplus gas. Such surplus digestion gas is generally burned by a surplus gas combustion device or the like, and thus has a problem of low energy efficiency. Conversely, when the consuming equipment needs a large amount of digestion gas in a short time, the deficiency of the digestion gas occurs, and there is a problem that the operation rate of the consuming equipment deteriorates.
[0004]
Accordingly, an object of the present invention is to provide a method for efficiently consuming such digestive gas in a consuming facility and an apparatus therefor.
[0005]
[Means for Solving the Problems]
The present inventors have conducted intensive studies to achieve the above object, and as a result, provided an adsorption storage facility for storing digested gas at a density several tens times higher than that of a low pressure gas holder, and provided a low pressure gas holder and an adsorption storage facility. A step of compressing the excess digestive gas as a means of storing excess digestive gas that cannot be stored in the low-pressure gas holder in the adsorption storage facility, and then removing water. Step, then adsorbent is filled, and the step of adsorbing in the adsorption tank provided with a heat insulating material capable of storing heat generated from the adsorbent at the time of digestion gas adsorption, further, continuously or intermittently from the adsorption tank A step of extracting part of the digestive gas and supplying the digestive gas to the compressing step, and consuming the digestive gas if a means is used such that the water vapor pressure in the step of removing water becomes a specific value or less. Effective with equipment It found that can be good for consumption.
In other words, when the generation of digestive gas is excessive, the digestive gas is stored in such an adsorption storage facility, and when the consumption of the consuming equipment increases, the digestive gas is released from the adsorption storage facility via the low-pressure gas holder. Can be insufflated. If the consuming equipment is planning to consume a large amount of digestive gas in a short period of time, store the digestive gas in the adsorption storage facility in advance, and release the digestive gas from the adsorption storage facility via the low-pressure gas holder when necessary. Can be insufflated. As a result, the necessary and sufficient amount of the gas consumed by the consuming equipment can always be supplied to the consuming equipment, so that the digestion gas can be efficiently consumed by the consuming equipment, and the present invention has been completed.
[0006]
That is, the present invention desulfurizes digestive gas generated during biological treatment, stores it in a low-pressure gas holder, and then consumes the digestive gas in a consuming facility. Device used In the use of Excess surplus that cannot be stored in the low-pressure gas holder The digestion gas is stored in the adsorption storage facility, and the excess digestion gas stored in the adsorption storage facility is supplied to the low-pressure gas holder as reflux or directly to the consumption equipment as necessary, Cannot be stored in low-pressure gas holder Store excess digestion gas in adsorption storage means Compresses the surplus digestive gas Process, then Remove moisture Process, then The heat generated from the adsorbent when the adsorbent is filled and the digestion gas is adsorbed is adsorbed in an adsorption tank provided with a heat insulating material capable of storing the heat. Process, and Extract some digestion gas continuously or intermittently from the adsorption tank The Supply to compression process A water vapor pressure in the step of removing moisture is 1226.5 Pa (9.2 mmHg) or less. Digestive gas characterized by Device used It is intended to provide a method of using.
The present invention also relates to such a digestive gas. Device used In the utilization method, a heat insulating material and a heater are provided in the adsorption tank, and the heat storage material of the heat insulating material and the heating by the heater are added to the adsorbent when the gas is desorbed from the adsorption tank. Device used It is intended to provide a method of using.
The present invention also relates to such a digestive gas. Device used In the use of Cannot be stored in low-pressure gas holder Store excess digestion gas in adsorption storage means But, The After compressing excess digestion gas and dehumidifying, then the adsorbent is filled, and the adsorbent and the heat medium can exchange heat via the heat exchange mechanism installed on the wall surface or inside the adsorption tank, Digestion gas that adsorbs adsorbent while cooling it with heat medium Device used It is intended to provide a method of using.
The present invention also relates to such a digestive gas. Device used In the method of utilization, stored in the adsorption storage facility Surplus Recirculation of digestive gas to low pressure gas holder and supply to consuming equipment means However, the digestion gas adsorbed by the adsorbent is filled in the adsorbent, and the adsorbent and the heat medium can exchange heat through a heat exchange mechanism installed on the wall surface or inside the adsorption tank, The adsorbent is desorbed while being heated with a heating medium, and the digestion gas is returned to the low-pressure gas holder using the pressure in the adsorption tank or with a blower, or supplied directly to the consumption equipment. Device used It is intended to provide a method of using.
The present invention also relates to such a digestive gas. Device used In the digestion gas, wherein the fin is provided on the adsorption tank from the wall to the center of the adsorption tank. Device used It is intended to provide a method of using.
The present invention also relates to such a digestive gas. Device used Digestion gas that removes water by deliquescent dehumidification Device used It is intended to provide a method of using.
The present invention also relates to such a digestive gas. Device used Of digestion gas using a portable adsorption tank as an adsorption storage facility Device used It is intended to provide a method of using.
The present invention also relates to such a digestive gas. Device used In the method of use, digestion gas that removes water and then removes components other than methane and carbon dioxide by activated carbon upstream of the adsorption tank Device used It is intended to provide a method of using.
[0007]
The present invention also relates to such A digestive gas utilization device for performing the method, In a digestion gas utilization device having a desulfurization tower for desulfurizing digestion gas, a low-pressure gas holder for storing digestion gas supplied from the desulfurization tower, and a consumption facility for consuming digestion gas supplied from the low-pressure gas holder, Low pressure gas holder Can't store Adsorbing and storing surplus digestion gas, and having an adsorption storage device that circulates the stored digestion gas to a low-pressure gas holder as needed or directly supplies the gas to the consumption device, wherein the adsorption storage device compresses the digestion gas. A gas compressor, a dehumidifier that removes moisture from the digestion gas supplied from the gas compressor, and a heat insulator that is filled with an adsorbent for the digestive gas and that can store heat generated from the adsorbent when the digestive gas is adsorbed. Material is provided, and an adsorption tank that adsorbs and stores the digestion gas supplied from the dehumidifier, and continuously or intermittently extracts some digestion gas from the adsorption tank. The An object of the present invention is to provide a digestion gas utilization device, which is provided with a return line for supplying a gas compressor.
In addition, the present invention provides a digestion gas utilization device in which the digestion gas utilization device is provided with a heater for heating at least one of the adsorbent and the heat retaining agent in the adsorption tank.
Further, the present invention provides such a digestive gas utilization device, wherein the adsorption storage facility has a gas compressor for compressing digestive gas, a dehumidifier for removing moisture from digestive gas supplied from the gas compressor, and a dehumidifier. For providing a digestion gas utilization device including an adsorption tank filled with an adsorbent capable of exchanging heat with a heat medium through a heat exchange mechanism installed on a wall surface or inside the adsorption tank of the digestion gas supplied from the apparatus It is.
The present invention also provides a digestion gas utilization device in which the dehumidification device is a deliquescent system in which the digestion gas is brought into contact with a hygroscopic compound to dehumidify the digestion gas.
In addition, the present invention provides a digestion gas utilization device in which the adsorption tank has a portable structure in the digestion gas utilization device.
Further, the present invention provides such a digestion gas utilization device, wherein a digestion gas provided between the downstream side of the dehumidifier and the upstream side of the adsorption tank is provided with an organic component removal device that adsorbs and removes components other than methane and carbon dioxide by activated carbon. Is provided.
[0008]
BEST MODE FOR CARRYING OUT THE INVENTION
FIG. 1 shows an embodiment of the digestion gas utilization device of the present invention. The digestion gas utilization apparatus 1 includes a desulfurization tower 2, a methane concentrator 6, a low-pressure gas holder 3, a consumption facility 4, and an adsorption storage facility 5. The desulfurization tower 2, the low-pressure gas holder 3 and the consuming equipment 4 are connected in series, and the adsorption storage equipment 5 is connected to the consuming equipment 4 via the low-pressure gas holder 3.
[0009]
Digestion gas, especially if it is biologically processed waste generated in sewage treatment plants, food factories, beer manufacturing factories, livestock breeding facilities, etc. No restrictions. The composition of the digestion gas is generally composed mainly of methane, and is composed of carbon dioxide, hydrogen, nitrogen, hydrogen sulfide, mercaptan and the like.
[0010]
Generally, digestive gas contains hydrogen sulfide which is highly erodible. In the present invention, digestion gas is first desulfurized in a desulfurization tower. Means for desulfurization include dry desulfurization and wet desulfurization. In the dry desulfurization method, a molded desulfurization agent type is often used. In the molded desulfurizing agent method, a molded desulfurizing agent pelletized with iron powder, clay or the like is filled in a desulfurization tower and brought into contact with digestive gas, and the used desulfurizing agent taken out is disposed of. The wet desulfurization method includes a water washing type, an alkali washing type, and a chemical solution regeneration type. Among them, the water-washing type is a method in which digestion gas is brought into countercurrent contact with sewage treatment water in the case of sewage treatment, and well water, industrial water or tap water in other treatment plants. The temperature and pressure at the time of desulfurization may be the same as the digested gas generation state, and are not particularly limited. The concentration of hydrogen sulfide in the digested gas after desulfurization is preferably on the order of 0.1 ppm.
[0011]
The desulfurized digestion gas is stored in a low-pressure gas holder. In the absence of a low-pressure gas holder, all fluctuations in the amount of digested gas generated must be absorbed by the adsorption storage facility. Therefore, if a gas compressor is used as an element of the adsorption storage facility, for example, to compress and store the digestion gas in the adsorption storage facility, the capacity of the gas compressor must be adjusted to the maximum amount of digested gas generated. And a situation in which a large-capacity model must be selected unnecessarily occurs, which is not preferable. There are two types of low-pressure gas holders, a dry type and a wet type, and either type may be used.
[0012]
There is no particular limitation on the consumption equipment that consumes digestive gas, and examples thereof include various boilers such as a hot water boiler and a steam boiler, a fuel cell, a gas turbine (including a microturbine), and a gas engine. It also includes consumption facilities owned by gas companies to which gas is sold.
[0013]
Digestion gas, from the viewpoint of effective use of energy, it is preferable to remove carbon dioxide using a methane concentrator before storing it in a low-pressure gas holder after desulfurization or storing it in an adsorption storage facility, and to concentrate methane. . When the methane concentration is not performed, the calorific value of the digested gas released from the adsorption storage equipment described later changes. Therefore, it is preferable to provide a cushion tank to adjust the calorific value.
As a means of decarbonation, for example, a method of passing through an adsorption tower filled with a carbon dioxide adsorbent such as activated carbon, zeolite, or metal oxide; a method of degassing in vacuum using a gas separation membrane; a porous hollow fiber membrane And the like. Among these, it is preferable to use a porous hollow fiber membrane, particularly a hydrophobic hollow fiber membrane, because carbon dioxide can be selectively removed, and the membrane is compact and economical.
[0014]
The principle of removing carbon dioxide from digested gas using a hydrophobic hollow fiber membrane will be described. Two hydrophobic hollow fibers (for gas supply and for recovery) are placed in water. Since the hollow fiber is hydrophobic, no water enters into it. A high-concentration digestive gas (after removing hydrogen sulfide) is passed through the supply hollow fiber, and the gas concentration in the recovery hollow fiber is kept low. Carbon dioxide has a higher solubility in water than other gas components. For this reason, carbon dioxide diffuses and dissolves in water through the micropores of the hollow fiber membrane in a larger amount than other gas components. The carbon dioxide that has reached the recovery hollow fiber membrane is recovered through the reverse process. There are many commercially available hollow fiber membranes (for example, degassing membrane modules manufactured by NOK Corporation), and any of them may be used.
[0015]
A methane concentrating device suitable for use in the present invention for removing carbon dioxide from digestive gas and concentrating methane gas using a hydrophobic hollow fiber membrane is described below. FIG. 3 is a schematic configuration diagram illustrating an example of the methane gas concentrating device. The absorption part A and the diffusion part B circulate and supply water through a pump C. The digestion gas is supplied to a hollow fiber membrane (not shown) in the absorption section A. A large amount of carbon dioxide in the gas dissolves in the water in the absorption section A, and the digestion gas in which the carbon dioxide content is reduced and methane gas is concentrated is exhausted. The carbon dioxide dissolved in the water is sent to the emission part B via the pump C. The carbon dioxide sent to the emission part B is collected by a hollow fiber membrane (not shown) in the emission part B and exhausted.
[0016]
The digestion gas adsorption storage method and the method of returning the stored digestion gas to the low pressure gas holder or supplying it directly to the consuming equipment can store the digestion gas efficiently and easily, and if necessary, easily. The method is not particularly limited as long as it can be eliminated, but the method described below is preferable.
[0017]
FIG. 2 shows an embodiment of the adsorption storage equipment used in the present invention. This adsorption storage equipment includes a gas compressor 51 for compressing digestive gas, a dehumidifier 52 for removing moisture from digestive gas supplied from the gas compressor 51, and an adsorbent for digestive gas, which is filled with gas at the time of gas adsorption. A heat insulating material capable of storing heat generated from the adsorbent is provided, and an adsorber tank 53 for adsorbing digestive gas supplied from the dehumidifier 52 is provided. The gas compressor 51, the dehumidifier 52, and the adsorption tank 53 are connected in series. The line 531 is a line for returning the digested gas desorbed from the adsorption tank 53 to the low-pressure gas holder, and the line 532 is a line for branching the line 531 halfway and returning the digested gas to the gas compressor 51. This line 532 is for continuously or intermittently extracting a part of gas from the adsorption tank 53 and supplying it to the gas compressor 51.
[0018]
Next, a method for performing adsorption storage of digestive gas using the adsorption storage facility configured as shown in FIG. 2 will be described.
First, the digestion gas supplied from the low-pressure gas holder is introduced into the gas compressor 51 and compressed. The gas compression ratio here is not particularly limited, but it is preferable to compress the digestion gas to a pressure at which the adsorption efficiency of the digestion gas in the adsorption tank 53 is improved, for example, to a normal pressure to about 2 MPa. Examples of the gas compressor 51 include a compressor and the like. It is preferable that the compressor is an oil-free type in which oil mist is not scattered in a subsequent process.
[0019]
The digestion gas compressed by the gas compressor 51 is supplied to a dehumidifier 52 to remove moisture. As means for removing moisture in the digestion gas, for example, a means for dehumidifying using an adsorbent capable of selectively adsorbing moisture, or a means for mechanically dehumidifying can be used. The use of a device is particularly preferred. The deliquescent dehumidifier contacts a digestive gas containing water with a deliquescent salt, for example, a hygroscopic compound such as calcium chloride, magnesium chloride, or crude sodium chloride, to selectively remove moisture in the gas. This type of deliquescent dehumidifier does not include an electric motor, and thus has the advantage that the running cost is extremely low as compared with mechanical dehumidification. Also, there is no danger of igniting the gas, and it can be used in explosion-proof areas that handle flammable gas. Further, by using a safe natural product moisture absorbent such as crude sodium chloride, it is possible to easily dispose or reuse the salt desorbed by absorbing water.
[0020]
By removing water, the water vapor pressure in the digestive gas is preferably adjusted to 9.2 mmHg corresponding to a dew point of 10 ° C. or less, and particularly to 4.6 mmHg corresponding to a dew point of 0 ° C. or less at a pressure at which the gas is to be adsorbed. By setting the dew point to 0 ° C. or lower, the efficiency of digestion gas adsorption is further improved. The water vapor pressure can be controlled by the flow rate of the digestion gas introduced into the dehumidifier 52. The digested gas from which water has been removed in the dehumidifier 52 is supplied to the adsorption tank 53.
[0021]
In a more preferred embodiment, an organic component removing device that adsorbs and removes components other than methane and carbon dioxide with activated carbon is provided between the downstream side of the dehumidifying device 52 and the upstream side of the adsorption tank 53, and the digested gas that has been dehumidified is subjected to organic treatment. The gas is introduced into a component removing device, and organic components other than methane and carbon dioxide contained in the gas are adsorbed and removed with activated carbon. Examples of the organic components "other than methane and carbon dioxide" contained in the digested gas include organic compounds such as toluene, octane, and tridecane. It is known that when these components are supplied to the adsorption tank 53 together with the digestion gas, they are adsorbed by the adsorbent preferentially over methane, so that the adsorption capacity of the adsorbent is reduced. Therefore, by removing these components from the gas supplied to the adsorption tank 53 in advance, it is possible to prevent a decrease in the adsorption ability due to these components.
[0022]
This organic component removal device may be any device that can adsorb and remove organic components other than methane such as toluene, octane, and tridecane by bringing the digested gas after dehumidification into contact with activated carbon. It is preferable to use a cylindrical pressure vessel from the viewpoint of easy handling. As the activated carbon used for adsorption and removal of organic compounds other than methane, various types of activated carbon that are generally commercially available can be used, and it is particularly preferable to use activated carbon that is sold as “for recovering an organic solvent”.
[0023]
The adsorption tank 53 is filled with an adsorbent. Further, at least one of the inner wall side and the outer wall side of the adsorption tank 53 and / or the tank of the adsorption tank 53 is provided with a heat insulating material capable of storing heat of adsorption generated from the adsorbent during gas adsorption. Further, the adsorption tank 53 is provided with a heater such as an electric heater or a trace line, and is configured to add heat storage of the heat insulating material and heating by the heater to the adsorbent when the adsorption tank 53 desorbs gas. In particular, a configuration in which an electric heater or a trace line is provided on the outer wall of the adsorption tank 53, and the temperature is covered with a heat insulating material to maintain the temperature is preferable.
[0024]
Examples of the adsorbent include activated carbon, artificial zeolite, natural zeolite, silica gel, organometallic complexes (copper fumarate, copper terephthalate, etc.), and one or more of these can be used. When activated carbon or the like is used as an adsorbent, a specific surface area of 1000 m usually used for gas treatment ² / G, a pore diameter of 20 ° or less, and a pore volume of 0.2 to 1.0 ml / g are preferred. The temperature and pressure at the time of adsorption are not particularly limited, but the temperature is preferably lower than the outside air temperature. The pressure is preferably normal pressure or higher, particularly preferably normal pressure to 2 MPa. As the heat insulating material, conventionally known inorganic heat insulating materials and organic heat insulating materials can be used, and preferably, foamed hard urethane and glass wool are used.
[0025]
The digestion gas supplied to the adsorption tank 53 is adsorbed on the adsorbent filled in the adsorption tank 53 and stored. During the adsorption storage, the adsorbent generates heat, and the temperature in the adsorption tank 53 rises. The generation of this heat of adsorption slightly lowers the gas adsorption efficiency of the adsorbent, but in order to make effective use of the heat of adsorption, this heat of adsorption is positively stored in the heat insulating material, and the heat is absorbed during desorption. Used as a part of the heat source for heating the agent.
[0026]
When the digestion gas is taken out of the adsorption tank 53 after the digestion gas has been absorbed and stored, the adsorbent in the adsorption tank 53 is heated. In order to achieve higher thermal efficiency, it is desirable to maintain the temperature of the adsorbent or the heat retaining agent by heating the gas as needed during adsorption storage of the gas. As described above, at the time of this gas desorption, the thermal energy stored in the heat insulating material provided in the adsorption tank 53 is actively used, and the heat energy is further supplied from the electric heater or the trace line attached to the adsorption tank 53. And take out the digestion gas. The digestion gas released from the adsorption tank 53 is transferred to the low-pressure gas holder through the line 531.
[0027]
The digestion gas released from the adsorption tank 53 may be transferred to a fuel consuming area (consuming equipment) by, for example, a pipeline. However, there are some cases where pipeline transfer from a place where digestive gas is generated is not economically viable. Therefore, the adsorption tank 53 for adsorbing the digestion gas is portable, that is, the gas piping and the gantry of the adsorption tank 53 are detachable from the system, and the adsorption tank 53 can be efficiently transported regardless of the location of the fuel demand area. Is preferred. The shape of the portable adsorption tank is not particularly limited as long as it can be transported by a transport vehicle such as a truck.
[0028]
Further, in order to adsorb and store a target amount of digestion gas, the adsorption tank 53 may use either a plurality of small-capacity tanks or a single tank having a capacity satisfying the target amount. In the former case, there is an advantage that the cost can be reduced by making the adsorption tank 53 a standard product, and because it is small, it is easy to make it portable and the maintenance burden on the user is light. In the latter case, there is an advantage that the installation area is small.
[0029]
When the digestion gas is introduced into the adsorption tank 53 and the digestion gas is adsorbed and stored, methane gas, which is a main component of the digestion gas, is adsorbed, and other gas components, particularly water, are gradually concentrated. Accumulate in If the water content in the adsorption tank 53 increases, the adsorbing ability of the adsorbent decreases. In order to prevent the adsorption efficiency from decreasing, it is preferable that the adsorption storage facility 5 is provided with a return line 532 that continuously or intermittently extracts a part of the gas from the adsorption tank 53 and supplies the gas to the gas compressor 51. By performing the adsorption storage of the digestion gas while extracting a part of the gas in the adsorption tank 53 through the return line 532 from the adsorption tank 53, the concentration of the water in the adsorption tank 53 is prevented, and the adsorbent due to the water is prevented from being concentrated. A decrease in adsorption efficiency can be prevented. The gas sent to the gas compressor 51 through the return line 532 is mixed with the digestion gas sent from the low-pressure gas holder, compressed, and dehumidified.
[0030]
FIG. 4 shows an example of another embodiment of the adsorption storage equipment used in the present invention. The digestion gas is pressurized by the gas compressor 51. Next, the digestion gas is dehumidified by the dehumidifier 52. The adsorption tank 53 is provided with a jacket and a trace line on the outside of the wall surface so that a low-temperature heat medium such as cold water can be circulated. The digestion gas exhausted from the dehumidifier 52 is sent to the adsorption tank 53 and is adsorbed by the adsorbent. The temperature rise of the adsorbent due to the heat of adsorption is suppressed by the low-temperature heat medium, and the adsorbent is always kept at an appropriate temperature.
[0031]
Next, a method of performing adsorption storage of digestive gas using the adsorption storage facility configured as shown in FIG. 4 will be described.
The digestion gas supplied from the low-pressure gas holder is compressed by the gas compressor 51. The type and compression ratio of the gas compressor are the same as above. Next, the digestion gas is sent to the dehumidifier 52 to dehumidify it. The type of dehumidifying device, dehumidifying performance, etc. are the same as described above.
[0032]
Next, the dehumidified digestion gas is adsorbed in the adsorption tank 53 filled with the adsorbent while cooling the adsorbent with a low-temperature heat medium. The adsorbent tank 53 filled with the adsorbent is capable of exchanging heat between the adsorbent and the heat medium via a heat exchange mechanism provided on the wall surface or inside the adsorber tank 53. It is preferable to provide, for example, a jacket, a trace line, or the like on the wall surface of the adsorption tank 53 so that heat exchange between the heat medium and the adsorbent through the wall surface can be performed efficiently. Further, it is preferable to install a heat exchange mechanism such as a tube or a trace line inside the adsorption tank 53. The cooling of the adsorbent is promoted by flowing a heat medium through them. Examples of the heat medium include low-temperature heat medium such as cold water, antifreeze, low-temperature air, and outside air. However, from the viewpoint of thermal efficiency with the adsorbent, cold water, antifreeze, and the like are preferable. The ratio between the amount of the adsorbent filled and the flow rate of the heat medium is not particularly limited, and may be appropriately selected according to the composition of the digested gas, the flow rate, and the like. The cooling temperature of the adsorbent is not particularly limited, but is preferably 35 ° C. or lower, particularly preferably 25 ° C. or lower.
[0033]
The digestion gas sent into the adsorption tank 53 is adsorbed by the adsorbent. At this time, the adsorbent easily rises in temperature due to the heat of adsorption, but exchanges heat with the low-temperature heat medium through a heat exchange mechanism installed on the wall surface or inside the adsorption tank, and has excellent heat exchange efficiency. Can always maintain an appropriate temperature. Therefore, the adsorption efficiency of the digestion gas to the adsorbent is higher than that of the conventional method.
As the adsorbent, those similar to the above can be used, and the temperature and pressure during adsorption are the same as above.
[0034]
Note that the adsorption tank 53 is preferably provided with fins from the wall surface toward the center of the adsorption tank. Thereby, since the heat exchange area increases, the heat exchange between the heat medium and the adsorbent is further promoted, and the digestion gas adsorption efficiency is further improved. There is no particular limitation on the shape of the fins.
[0035]
The method of circulating the digested gas absorbed and stored into the low-pressure gas holder and the method of supplying the gas to the consuming equipment are as follows. It is desorbed while heating, and is supplied to the low-pressure gas holder by reflux or directly to the consuming equipment using the pressure in the adsorption tank or by a blower or the like. The adsorption tank filled with the adsorbent is capable of exchanging heat between the adsorbent and the heat medium via a heat exchange mechanism provided on the wall surface or inside the adsorption tank. It is preferable to provide, for example, a jacket, a trace line, or the like on the wall surface of the adsorption tank so that heat exchange between the heat medium and the adsorbent can be efficiently performed through the wall surface. It is preferable to install a heat exchange mechanism such as a tube or a trace line inside the adsorption tank. Heating the adsorbent is promoted by flowing a heat medium through them. Examples of the heat medium include high-temperature heat medium such as steam, dry high-temperature air, and hot water. From the viewpoint of heat efficiency with the adsorbent, steam, hot water, and the like are preferable. The ratio between the amount of the adsorbent filled and the flow rate of the heat medium is not particularly limited, and may be appropriately selected according to the composition of the digested gas, the flow rate, and the like. The heating temperature of the adsorbent is not particularly limited, but is preferably 5 ° C. or more, particularly preferably 15 ° C. or more.
[0036]
At the time of digestion gas desorption, since the temperature of the adsorbent is likely to decrease, the desorption is not easily promoted, but the adsorbent interacts with the high-temperature heat transfer medium through a heat exchange mechanism installed in the wall surface or inside the adsorption tank. Since the heat exchange is performed and the heat exchange efficiency is excellent, the adsorbent can always maintain an appropriate temperature. For this reason, the desorption efficiency of the digestion gas from the adsorbent is higher than that of the conventional method.
[0037]
The adsorption tank is preferably provided with fins from the wall surface toward the center of the adsorption tank. Thereby, since the heat exchange area increases, the heat exchange between the heat medium and the adsorbent is promoted, and the desorption efficiency of the digestion gas is further improved. There is no particular limitation on the shape of the fins.
[0038]
【The invention's effect】
According to the present invention, when the generation of digestive gas is excessive, the digestive gas is stored in the adsorption storage facility, and when the consumption of the consuming equipment increases, from the adsorption storage facility via the low-pressure gas holder. Alternatively, the digestion gas can be sent directly to the consuming equipment. Also, if the consuming equipment is planning to consume a large amount of digestive gas in a short time, store the digestive gas in the adsorption storage equipment in advance, and when necessary, from the adsorption storage equipment via a low-pressure gas holder or directly. Digestion gas can be sent to the consuming equipment. As a result, since the necessary and sufficient amount to be consumed by the consuming equipment can always be sent to the consuming equipment, the digestive gas can be efficiently consumed by the consuming equipment.
In particular, the adsorption storage method is such that after the digestion gas is compressed and then the water is removed, the adsorbent is filled, and in the adsorption tank provided with a heat insulating material capable of storing heat generated from the adsorbent during gas adsorption. If the gas is adsorbed, the heat of adsorption generated at the time of gas adsorption is stored in the adsorption tank, and the heat can be used at the time of gas desorption, so that the equipment structure can be simplified and the energy required for operation can be reduced. Initial costs and running costs can be significantly reduced. Further, by providing a heater in the adsorption tank and adding the heat storage of the heat insulating material and the heating by the heater to the adsorbent when desorbing the gas in the adsorption tank, this effect can be made more remarkable.
[0039]
In particular, the adsorption storage method compresses digestion gas and then removes water, then is filled with an adsorbent, and the adsorbent and the heat medium are transferred through a heat exchange mechanism installed on a wall surface or inside the adsorption tank. In the case of a method in which the adsorbent is adsorbed while cooling it with a heat medium in the adsorption tank that can be replaced, the method of refluxing to the low-pressure gas holder and the method of supplying the gas to the consuming equipment include digestive gas adsorbed by the adsorbent The adsorbent is filled with the adsorbent, and the adsorbent and the heat medium are removed while heating the adsorbent with the heat medium in an adsorption tank in which heat can be exchanged through a heat exchange mechanism installed on the wall surface or inside the adsorption tank. This effect can be made more remarkable in the case of a method of recirculating to a low-pressure gas holder using a pressure in the adsorption tank or by using a blower or the like, or supplying to a consuming facility.
In addition, in particular, in the above-mentioned adsorption storage method, by adsorbing and removing components other than methane and carbon dioxide by activated carbon upstream of the adsorption tank after dehumidification, the adsorbent is preferentially adsorbed to the adsorbent over methane and carbon dioxide. Organic components other than methane, such as toluene, octane, and tridecane, which lower the capacity of methane, are removed, and a decrease in the digestion gas storage capacity of the adsorption tank can be prevented, and this effect can be remarkable.
[Brief description of the drawings]
FIG. 1 is a schematic configuration diagram showing an example of a digestive gas utilization device of the present invention.
FIG. 2 is a schematic configuration diagram showing an example of an adsorption storage facility used in the present invention.
FIG. 3 is a schematic configuration diagram showing an example of an adsorption storage facility used in the present invention.
FIG. 4 is a schematic configuration diagram showing an example of an adsorption storage facility used in the present invention.
[Explanation of symbols]
1: Utilization device for digestion gas
2: Desulfurization tower
3: Low pressure gas holder
4: Consumer equipment
5: Adsorption storage equipment
6: Methane concentration equipment
51: Gas compressor
52: Dehumidifier
53: Adsorption tank
Recirculation line to 531 low pressure gas holder
532: Return line to gas compressor
A: Absorber
B: Emission part
C: Pump

Claims (14)

After desulfurizing digestive gas generated during biological treatment, storing it in a low-pressure gas holder , and then using excess digestive gas that cannot be stored in the low-pressure gas holder in the method of using the digestive gas utilization device that is consumed by the consuming equipment, it is adsorbed and stored. It is stored in the facility, and the excess digestion gas stored in the adsorption storage facility is returned to the low-pressure gas holder or supplied directly to the consuming equipment as needed, and the excess digestion gas that cannot be stored in the low-pressure gas holder is removed. Means for storing in the adsorption storage facility is a step of compressing the surplus digestive gas, a step of removing water , and then a heat retaining step in which the adsorbent is filled and heat generated from the adsorbent at the time of digestion gas adsorption is stored. step of wood is adsorbed in the adsorption vessel which is provided, further extracted continuously or intermittently part of the digester gas from the adsorption vessel, for supplying a digestion gas to the step of the compressed Engineering The a method utilizing digestion gas utilization device the water vapor pressure in the step of removing moisture is characterized by such a 1226.5Pa (9.2mmHg) or less. The heat insulating material and a heater in the suction tank is provided, a method utilizing the digestion gas using apparatus according to claim 1 in which added to the adsorbent and heating by heat storage and heating of the heat insulating material during gas desorption of the adsorption vessel. Means for storing a surplus of digestion gas which can not be stored in the low-pressure gas holder adsorption storage facility, dehumidified after compressing the excess digestion gas, and then the adsorbent is filled, the adsorbent and the heat transfer medium wall or Obtaining adsorption vessel inside through the heat exchange mechanism installed in the adsorption vessel which can be heat exchanged adsorbent digestion gas using apparatus according to claim 1, wherein in which is adsorbed while cooling with heat medium to. Supply means to reflux and consumption facilities to low pressure gas holder excess digestion gas stored in adsorption storage facility, the adsorbed digestion gas to the adsorbent, the adsorbent is filled, the adsorbent and the heat transfer medium The adsorbent is desorbed while being heated with a heat medium in an adsorption tank that can exchange heat via a heat exchange mechanism installed on the wall surface or inside the adsorption tank, and using the pressure in the adsorption tank or a blower, etc. The method of using a digestion gas utilization device according to any one of claims 1 to 3, wherein the gas is refluxed to a low-pressure gas holder or directly supplied to a consuming facility. Obtaining digestion gas utilization apparatus according to claim 3 or 4, wherein the fins are provided toward the adsorption vessel center from the wall surface in the suction tank. The method of using a digestion gas utilization device according to any one of claims 1 to 5, wherein the water removal is performed by dehumidification using a deliquescence method. The use method of the digestion gas utilization device according to any one of claims 1 to 6, wherein a portable adsorption tank is used as the adsorption storage facility. After removal of the water, method of use of the digestion gas using apparatus of any one of claims 1 to 7, characterized in that removing adsorbed by methane upstream of the adsorption vessel, the components other than carbon dioxide activated carbon. A digestion gas utilization device for performing the method according to any one of claims 1 to 8 , wherein the desulfurization tower desulfurizes the digestion gas, and a low-pressure gas holder that stores the digestion gas supplied from the desulfurization tower. And a digestion gas utilization device having a consumption facility for consuming the digestion gas supplied from the low-pressure gas holder, wherein the excess digestion gas that cannot be stored by the low-pressure gas holder is absorbed and stored, and the stored digestion gas is required. Has an adsorption storage facility that recirculates to the low-pressure gas holder or supplies the gas directly to the consuming equipment, and the adsorption storage facility uses a gas compressor that compresses the digestion gas and a digestion gas supplied from the gas compressor. A dehumidifier for removing water and a heat insulator filled with an adsorbent for digestive gas and capable of storing heat generated from the adsorbent when digestive gas is adsorbed are provided, and digestion gas supplied from the dehumidifier is provided. The scan is intended and a suction tank for adsorption storage, and an extracted continuously or intermittently part of the digester gas from the adsorption vessel, characterized in that a return line for supplying to the gas compressor digestion Gas utilization equipment. The digestion gas utilization device according to claim 9, wherein a heater for heating at least one of the adsorbent and the heat retaining agent is provided in the adsorption tank. An adsorption storage device, a gas compressor for compressing digestive gas, a dehumidifier for removing moisture from the digestive gas supplied from the gas compressor, The digestion gas utilization device according to claim 9, further comprising an adsorption tank filled with an adsorbent capable of exchanging heat with a heat medium via a heat exchange mechanism installed in the digestion gas. The digestive gas utilization device according to any one of claims 9 to 11, wherein the dehumidifier is of a deliquescence type in which the digestive gas is brought into contact with the hygroscopic compound to dehumidify. The digestion gas utilization device according to any one of claims 9 to 12, wherein the adsorption tank has a portable structure. 14. An organic component removing device for adsorbing and removing components other than methane and carbon dioxide with activated carbon is provided between the downstream side of the dehumidifying device and the upstream side of the adsorption tank. Use device of digestion gas as described.

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