JP5072638B2 - Biogas biodesulfurization equipment - Google Patents

Description

  The present invention relates to a biogas biodesulfurization apparatus, and more particularly to a biogas biodesulfurization apparatus generated by anaerobic digestion treatment of organic wastewater such as sewage and industrial wastewater.

  As a method for treating organic waste such as sewage sludge and garbage and organic waste water such as food factory effluent, the methane fermentation treatment method has been widely applied. In the methane fermentation treatment method, organic wastewater is introduced into a biological reaction tank, organic matter is decomposed by the methane fermentation bacteria group filled in the reaction tank, biogas containing methane gas as a main component is generated, and organic matter in the wastewater is also generated. Is a treatment method for decomposing and removing. However, when the sulfur component such as protein is contained in the waste water, the sulfur component is reduced by the action of the sulfate reducing bacteria, and hydrogen sulfide gas is contained in the biogas.

  By the way, when methane gas contained in biogas is used as a fuel such as a boiler, it is necessary to remove hydrogen sulfide gas contained in biogas. This is because when the biogas is burned, the hydrogen sulfide gas in the biogas is oxidized to produce sulfur oxide, which may corrode the equipment.

  As a method for removing hydrogen sulfide gas contained in biogas, there are a dry desulfurization method in which adsorption is performed using an adsorbent mainly composed of iron oxide, or a wet desulfurization method in which an aqueous solution using an alkali is absorbed and removed. It's being used. However, these methods are systems in which running costs increase because chemicals such as an adsorbent are required for adsorption and the adsorbent after adsorption becomes waste.

Therefore, as a system for performing desulfurization at a low running cost, a technique (Patent Document 1) for removing hydrogen sulfide in biogas by filling a reaction tank with a carrier attached with microorganisms that oxidize and decompose hydrogen sulfide has been proposed. .
In this desulfurization technique, a problem has been pointed out that the packed bed is likely to be blocked by microorganisms grown on the lower part of the packed bed or the support part of the packed bed or by simple sulfur produced by oxidation of the removed hydrogen sulfide. As a means for solving this, a method of flowing a biogas in a downward flow, using a carrier lighter than water, spreading water above the height of the packed bed, blowing air from the lower part, causing the carrier to flow in water and washing (Patent Document 2) has been proposed.
JP-A-2-26615 Japanese Patent No. 3750648

  In order to remove hydrogen sulfide gas contained in biogas by sulfur-oxidizing bacteria, it is necessary to retain a sufficient amount of microorganisms on the carrier of the packed bed. However, if water washing is performed to remove elemental sulfur accumulated in the packed bed, microorganisms may be washed together with elemental sulfur. That is, when the cleaning time is short, the elemental sulfur cannot be removed sufficiently and clogging is likely to occur. On the other hand, when the cleaning time is extended, a sufficient amount of microorganisms necessary for removing hydrogen sulfide cannot be secured, which causes a problem that the performance of removing hydrogen sulfide after cleaning is deteriorated. Even during cleaning, since the carrier flows in water, the cleaning efficiency is high, but the carrier support plate is fixed, so that the adhering material is not sufficiently separated by the cleaning, and the processing efficiency is reduced due to the blockage of the carrier support plate. Problem occurs.

  Further, when the height of the biological packed bed is increased, oxygen in the air mixed in the lower portion of the packed bed is consumed. For this reason, when the amount of aeration is small, there is a case where the microorganisms in the upper part of the packed bed cannot sufficiently play an active role.

  The present invention has been made to solve the above-described problems, and can prevent clogging in the carrier packed bed, hold microorganisms adhering to the carrier, supply necessary oxygen to the packed bed, and thus stable treatment. An object of the present invention is to provide a biodesulfurization apparatus for biogas that can be used.

The biogas biodesulfurization apparatus according to the present invention includes a bioreactor into which biogas generated by anaerobic fermentation of organic waste is introduced, and a microorganism arranged in two or more stages in the bioreactor. A carrier packed layer including a carrier to which is attached, an air supply means for mixing air into the lower part of the biological reaction tank, a watering mechanism for spraying water into the upper part of the biological reaction tank, and a plurality of carrier packed layers And a cleaning air pipe for cleaning each carrier packed bed .

  According to the present invention, it is possible to provide a biodesulfurization apparatus for biogas that can prevent clogging in the carrier packed bed and can retain microorganisms attached to the carrier and can be stably treated.

Hereinafter, the biogas biodesulfurization apparatus according to the present invention will be described in more detail.
As described above, the biogas biodesulfurization apparatus of the present invention includes a bioreaction tank, two or more stages of a carrier packed bed, air supply means, and a watering mechanism.
The amount of proliferated microorganisms and produced single sulfur, which is a clogging factor of the packed bed, is proportional to the amount of hydrogen sulfide removed, so the bottom of the packed bed on the inflow side of the biogas where the hydrogen sulfide concentration of the biogas is high In the packed bed, the amount of biogas increases in a large part. When the site is occluded, the biogas flow rate at the site adjacent to the site is then increased and the site is occluded. That is, when the packed bed is formed one by one, the occlusion site is propagated. Therefore, by dividing the packed bed, that is, by providing a plurality of packed beds, the packed layers serve as gas buffers, and the uneven flow of biogas is alleviated. This suppresses the clogging of the packed bed and stabilizes the hydrogen sulfide removal performance.

  In the present invention, the diameter of the carrier in the lower carrier-packed layer is preferably large in the diameter of the carrier in the upper carrier-packed layer. The reason for this is that, by adopting such a configuration, it is possible to extend the period up to the blockage by increasing the gaps in the lower carrier-filled layer, and thus by reducing the number of washings, the lower carrier-filled layer. This is because the amount of microorganisms adhering to the substrate can be increased, and the processing efficiency can be improved.

  In the present invention, it is preferable that a cleaning air pipe is arranged for each of the plurality of carrier packed layers, and that each of the carrier packed layers can be cleaned. The reason for this is that only the lower part or the upper part where solids are likely to deposit can be washed, so that it is possible to prevent the clogging of the reaction tower, and only the clogged support packed bed is washed. Therefore, it is possible to prevent the processing performance from deteriorating due to insufficient microorganisms after washing.

  In the present invention, it is preferable that a watering mechanism is arranged for each of the plurality of carrier packed layers or every other plurality. That is, when the watering mechanism is arranged only in the upper part of the reaction tower, if the flow rate from the watering mechanism is increased in order to prevent solids from accumulating in the lower support packing layer, it adheres to the upper support packing surface. Since microorganisms are also caused to flow, it may cause a decrease in the amount of microorganisms inside the reaction tower, which may cause deterioration in the performance of biodesulfurization. However, by arranging the watering mechanism having the above configuration separately from the watering mechanism on the upper stage side, it is possible to wash and remove the solid matter accumulated in the carrier packed layer on the lower stage side. In addition, the watering mechanism is configured such that when a plurality of carrier packed layers, for example, two carrier packed layers are arranged, between the upper and lower carrier packed layers, and for example, when six carrier packed layers are arranged, for example, Although it can arrange | position every 2nd, the example of arrangement | positioning is not limited to these.

  In the present invention, it is preferable that a watering mechanism other than the uppermost stage, for example, a watering nozzle is upward. In addition to the upper watering mechanism, for example, another watering mechanism is disposed between the upper and lower carrier-filling layers, and this is arranged upward so that the carrier-supporting layer is supported by showering directly on the upper-side carrier-packing layer. It is possible to prevent clogging of the carrier-packed layer by always washing the plate and preventing the adhesion of simple sulfur to the support plate.

  In the present invention, it is preferable to increase the amount of water sprayed by the intermediate watering mechanism rather than the upper watering mechanism. As described above, the clogging of the packed bed tends to occur closer to the inflow side of the biogas, so by increasing the amount of watering of the watering mechanism near the inflow side of the biogas, the clogging of the packed bed can be prevented and unnecessary. Microbial flaking does not occur, and deterioration of the hydrogen sulfide removal performance of the biological desulfurization apparatus can be prevented.

  In the present invention, it is preferable to further include intermediate air supply means for introducing air into the intermediate portions of the plurality of carrier packed layers. With this configuration, even when the concentration of hydrogen sulfide contained in the inflowing biogas fluctuates or when the amount of microorganisms attached to the upper carrier packed bed increases, it adheres to the surface of the lower carrier packed bed. It becomes possible to supply oxygen to the microorganisms. Therefore, it becomes possible to maintain the activity of microorganisms, and it is possible to stabilize the processing efficiency even when the hydrogen sulfide concentration in the inflowing biogas varies.

Next, a specific example of a biogas biodesulfurization apparatus according to an embodiment of the present invention will be described with reference to the drawings. Note that the present embodiment is not limited to the following description.
(Example 1): Corresponding to claims 1 to 3
The biogas biodesulfurization apparatus according to the first embodiment will be described with reference to FIG. Reference numeral 1 in the figure is a biological reaction tank (reaction tower) into which biogas produced by anaerobic fermentation of organic waste is introduced. In this reaction tower, a first carrier packed layer 2a and a second carrier packed layer 2b each having a carrier to which microorganisms are attached are arranged one above the other. Here, the diameter of the carrier constituting the second carrier packed layer 2b is set larger than the diameter of the carrier constituting the first carrier packed layer 2a. An air supply pipe (air supply means) 3 for supplying air into the reaction tower 1, a biogas supply pipe 4 for supplying biogas into the reaction tower 1 are provided in the reaction tower 1 below the second carrier packed bed 2 b. , Drain pipes 5 for discharging the water supplied into the reaction tower 1 are provided. The reaction towers 1 below the first carrier packed bed 2a and the second carrier packed bed 2b are provided with cleaning air pipes 6a and 6b, respectively. In the upper part of the reaction tower 1, a watering mechanism (watering nozzle) 7 for supplying moisture to the microorganisms in the reaction tower 1 is arranged. In addition, the number 8 in a figure shows the exit piping (processing gas piping) of the processing gas after biological desulfurization.

  In the biogas biodesulfurization apparatus having such a configuration, the hydrogen sulfide gas contained in the biogas supplied from the lower part of the reaction tower 1 is filled with the first carrier packed bed 2a and the second carrier packed in the reaction tower 1. Oxidation treatment is performed by microorganisms adhering to the carrier packed layer 2b.

  That is, two stages of the first carrier packed layer 2a and the second carrier packed layer 2b are arranged in the reaction tower 1, and the cleaning air pipes 6a and 6b are arranged in order to be able to wash each of them. By doing so, it is possible to clean only the lower part or only the upper part where solids are likely to be deposited, so that it is possible to prevent the support packed layers 2a and 2b in the reaction tower 1 from being blocked. In addition, by washing only the blocked carrier packed layer, it is possible to prevent the processing performance from deteriorating due to insufficient microorganisms after washing.

  Furthermore, by increasing the carrier of the second carrier packed layer 2b where the accumulation of solid matter is larger than the carrier of the first carrier packed layer 2a, the period until the blockage with the second carrier packed layer 2b can be extended. it can. Therefore, by reducing the number of times of washing, the amount of microorganisms adhering to the second carrier packed layer 2b can be increased, and the processing efficiency can be improved.

  As described above, according to Example 1, since the adhered microorganisms can be retained in the cleaning when the carrier packed layer is closed, a stable treatment can be performed.

(Example 2): Corresponding to claims 4 and 5
The biogas biodesulfurization apparatus according to the second embodiment will be described with reference to FIG. However, the same members as those in FIG. 1 are denoted by the same reference numerals and the description thereof will be omitted, and only the main parts will be described.
Reference numeral 11 in the figure is an intermediate watering mechanism (watering nozzle) disposed upward in the reaction tower 1 between the first carrier packed bed 2a and the second carrier packed bed 2b.

  In the biogas biodesulfurization apparatus of FIG. 2, moisture can be supplied from the intermediate watering mechanism 11 together with the water supply from the watering mechanism 7 installed in the upper part of the reaction tower 1. As described in Example 1 above, the hydrogen sulfide gas contained in the biogas flowing in from the biogas supply pipe 4 at the bottom of the reaction tower 1 is supplied to the first carrier packed bed 2a and the second carrier packed bed 2b. Oxidized by microorganisms adhering to the surface and precipitated as simple sulfur. The elemental sulfur generated on the surface of the first carrier packed layer 2a falls to the second element packed bed 2b as the water spray flows.

  Since the elemental sulfur generated on the surface of the second carrier filling layer 2b and the elemental sulfur falling from the first carrier filling layer 2a are deposited on the second carrier filling layer 2b, the second carrier filling The volume of solids in layer 2b increases. At this time, if the flow rate from the sprinkling mechanism 7 is increased in order to prevent accumulation of solid matter in the second carrier packed layer 2b, microorganisms attached to the surface of the first carrier packed layer 2b will also flow. This may cause a decrease in the amount of microorganisms inside the reaction tower and may cause a deterioration in the performance of biodesulfurization.

  However, in the second embodiment, the second carrier packed layer 2b is supplied with additional watering from the intermediate watering mechanism 11 installed between the first carrier packed layer 2a and the second carrier packed layer 2b. The deposited solid matter can be removed by washing. At this time, microorganisms attached to the surface of the second carrier-packed layer 2b are also expected to flow out, but since the microorganisms falling from the first carrier-packed layer 2a are replenished, there is a sudden drop in performance. Can be prevented.

Further, by installing the intermediate watering mechanism 11 upward and showering directly on the first carrier packed layer 2a, the support plate of the first carrier packed layer 2a is always washed to block the first carrier packed layer 2a. It is also possible to prevent this.
As described above, according to the second embodiment, the first carrier packed layer 2a is prevented from being blocked by watering, and the attached microorganisms can be retained, so that stable treatment can be performed.

(Example 3): Corresponding to claim 6
The biogas biodesulfurization apparatus according to Example 3 will be described with reference to FIG. However, the same members as those shown in FIGS.
Reference numeral 12 in the figure denotes an intermediate air supply pipe (hollow air supply means) for supplying air disposed between the first carrier packed layer 2a and the second carrier packed layer 2b.

  In the biogas biodesulfurization apparatus of FIG. 3, air can be supplied from the intermediate air supply pipe 12 together with the air supply from the air supply pipe 3 installed at the lower part of the reaction tower 1. Microorganisms adhering to the carrier surfaces of the single packed layers 2a and 2b require oxygen for growth because the thiobacillus sulfur-oxidizing bacteria are aerobic bacteria. When the air supply pipe 3 is only at the same location as the biogas inflow portion, the hydrogen sulfide concentration in the biogas fluctuates, or the amount of microorganisms attached to the support surface of the upstream carrier packed bed 2a in the gas inflow Is excessively increased, oxygen supplied through the air supply pipe 3 is consumed by microorganisms, and oxygen necessary for inhabiting microorganisms attached to the carrier surface of the second carrier packed bed 2b on the downstream side can be supplied. There is a fear of disappearing.

  However, when the concentration of hydrogen sulfide contained in the inflowing biogas is changed by supplying air through the intermediate air supply pipe 12 between the plurality of divided carrier packed beds 2a and 2b, or when the first carrier packed bed is used. Even when the amount of microorganisms attached to the surface of the carrier 2a increases, oxygen can be supplied to the microorganisms attached to the carrier surface of the second carrier-packed layer 2b on the downstream side. Therefore, it becomes possible to maintain the activity of microorganisms, and it is possible to stabilize the processing efficiency even when the hydrogen sulfide concentration in the inflowing biogas varies.

  Note that the present invention is not limited to the above-described embodiment as it is, and can be embodied by modifying the constituent elements without departing from the scope of the invention in the implementation stage. Further, various inventions can be formed by appropriately combining a plurality of constituent elements disclosed in the embodiment. For example, some components may be deleted from all the components shown in the embodiment. Furthermore, you may combine suitably the component covering different embodiment. Specifically, in the above-described embodiment, for example, the case where the cleaning air is introduced into the reaction tower from two cleaning air pipes has been described, but the present invention is not limited thereto, and both the cleaning air pipes are connected by a manifold. Then, the cleaning air may be simultaneously introduced into the reaction tower.

The schematic block diagram of the biodesulfurization apparatus of the biogas which concerns on Example 1 of this invention. The schematic block diagram of the biodesulfurization apparatus of the biogas which concerns on Example 2 of this invention. The schematic block diagram of the biodesulfurization apparatus of the biogas which concerns on Example 3 of this invention.

Explanation of symbols

  DESCRIPTION OF SYMBOLS 1 ... Reaction tower, 2a ... 1st support packed bed, 2b ... 2nd support packed bed, 3 ... Air supply piping, 4 ... Biogas supply piping, 5 ... Drain pipe, 6a, 6b ... Cleaning air piping, 7, 11 ... Watering mechanism (watering nozzle), 8 ... Processing gas piping, 10 ... Intermediate air supply piping.

Claims (3)

A biological reaction tank into which biogas generated by anaerobic fermentation of organic waste is introduced;
A carrier-packed layer having a carrier to which microorganisms are attached, arranged in two or more stages in the biological reaction tank;
Air supply means for mixing air into the lower part of the biological reaction tank;
A watering mechanism for watering the upper part of the biological reaction tank ;
A biogas biodesulfurization apparatus comprising a cleaning air pipe arranged for each of a plurality of support packed beds and cleaning each of the support packed beds . 2. The biogas biodesulfurization apparatus according to claim 1 , wherein a watering mechanism is disposed for each of the plurality of carrier packed beds, and the watering mechanism other than the uppermost stage faces upward. The biogas biodesulfurization apparatus according to claim 1 , further comprising intermediate air supply means for introducing air into intermediate portions of the plurality of carrier packed beds.

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