JP2003305328A - Desulfurization equipment for digestion gas and desulfurization method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide desulfurization equipment for digestion gas easier in maintenance and control than before and capable of being efficiently operated at a low cost, and a desulfurization method using the same. <P>SOLUTION: The desulfurization equipment for digestion gas is equipped with a reaction column 3 receiving the digestion gas 1 produced by the methane fermentation of organic waste and packed with a filler 2 having microorganisms bonded thereto, an air supply means 4 for supplying air to the digestion gas before introduced into the reaction column and a spray nozzle 6 for sprinkling water 5 over the digestion gas after introduced. The filler comprises a synthetic resin body having a specific gravity of 0.9-1.05 and voids of 80-95% as a volume ratio and is charged on perforated plate-like support member 7 provided in the reaction column 3 without being fixed to the support member 7. In this case, it is preferable to downwardly provide a digestion gas introducing port 13 to the top part of the reaction column. <P>COPYRIGHT: (C)2004,JPO

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a digestion gas desulfurization apparatus and a desulfurization method, and more specifically, in utilizing digestion gas obtained by fermenting an organic waste as fuel gas in another facility, The present invention relates to a technique for removing hydrogen sulfide contained in the digestive gas and harmful to combustion from the digestive gas.

[0002]

2. Description of the Related Art At present, methane fermentation treatment is widely used for treating organic waste having a relatively high water content. In this methane fermentation treatment, a water slurry containing organic waste is supplied to a reaction vessel called a digestion tank, heated to an appropriate temperature (30 to 60 ° C) and held for a predetermined time to generate gas from the organic waste. And collect it. At that time, the components in the generated gas are 60 to 70% by volume of methane gas and 30 to 40% by volume of carbon dioxide. Further, hydrogen sulfide gas of 100 to 3000 ppm is usually contained as an impurity.

By the way, this gas is usually "digestion gas".
Is used as fuel gas. For example, it is a fuel for a gas engine for power generation, a gas turbine, a fuel cell, a boiler for producing hot water or steam, and the like. Then, when hydrogen sulfide is mixed, sulfur oxides are generated by combustion, so in any application, there is a problem of corroding mechanical parts such as engines or increasing the concentration of sulfur oxides in exhaust gas. . Therefore, it is necessary to reduce hydrogen sulfide before use.

In order to reduce this hydrogen sulfide, conventionally, a dry desulfurization apparatus for adsorbing and removing using an adsorbent such as iron oxide,
Wet desulfurization equipment by scrubber treatment using an oxidizing agent such as alkali or sodium hypochlorite as an aqueous solution has been used. However, these devices increase the running cost because the amount of adsorbent and chemicals used increases.
It was not economically favorable. Therefore, JP-A-2
JP-A-26615 discloses that a reactor (tower) is packed with a packing material in layers, and a biofilm mainly containing sulfur-oxidizing bacteria (hereinafter referred to as a microorganism) is formed on the surface of the packing material, and the packing layer is packed in the packing layer. There has been proposed a technique for microbiologically oxidizing and removing hydrogen sulfide by using a device for spraying water necessary for the action of microorganisms from the upper part of the packed bed while passing the gas to be treated (that is, the digestive gas). There is.

However, in this desulfurization technique,
The following problems have been pointed out, and these problems are obstacles to smooth and stable operation.

(1) The packing material is fixed in the tower or has a specific gravity of more than 1 (for example, 1.1 or more). In that case, the biofilm is enlarged and the packing material is increased. Even if the voids are closed, they cannot be washed sufficiently.

(2) The digestion gas to be treated is generally flowed from below to above the layer formed by the filler in a so-called "upstream flow". In this case, the lower part of the packed bed and the packed bed are treated. The elemental sulfur formed by the biofilm and the removed hydrogen sulfide being oxidized is concentrated and accumulated on the support member (for example, a screen, a net, etc.) in the shape of a porous plate that supports the cleaning, so that the frequency of cleaning increases. Further, although the screen is easily clogged, it does not flow during cleaning, so cleaning cannot be performed, and in the worst case, the operation is stopped.

(3) When hydrogen sulfide is removed and oxidized by organisms, the pH of the circulating water is lowered, so that the injection amount of alkali used for adjusting the pH of the water is increased.

(4) When the amount of air added to the digestion gas introduced into the reaction tower is adjusted so that the oxygen concentration of the digestion gas discharged from the reaction tower is at least about 500 ppm, the oxidative activity of microorganisms is lowered. There is a possibility that the processing will be insufficient.

(5) Even if an attempt is made to adjust the oxygen concentration of the digestion gas discharged from the reaction tower to a certain value, the optimum oxygen concentration varies depending on the temperature, inflowing gas components, etc., and therefore cannot be adjusted accurately.

[0011]

In view of the above circumstances, the present invention provides a desulfurization apparatus and a desulfurization method for a digestive gas, in which the maintenance of the apparatus is easier, more efficient, and more cost-effective than before. It is an object.

[0012]

In order to achieve the above object, the inventor has recognized that biological desulfurization is suitable for a desulfurization apparatus for digestive gas, and made earnest efforts to solve the problems of the prior art. Then, the result was embodied as the present invention.

That is, according to the present invention, a digestion gas generated by methane fermentation of an organic waste is introduced into a reaction tower filled with a filler to which microorganisms adhere, and the digestion gas before introduction into the reaction tower. In a digestive gas desulfurization apparatus comprising an air supply means for supplying air and a spray nozzle for spraying water on the digested gas after introduction, the filler has a specific gravity of 0.9.
It is characterized in that it is a synthetic resin body having voids of ˜1.05 and a volume ratio of 80 to 95%, and is filled without being fixed on the perforated plate-shaped support member provided in the reaction tower. It is a digester gas desulfurizer.

In this case, a sensor for measuring the pressure loss of the digestive gas flowing through the reaction tower or a sensor for measuring the pressure loss of the digestive gas is provided at the top of the reaction tower, and the measured value is input. When a pre-stored threshold value of pressure loss is exceeded, a signal output from the digestion gas to the reaction tower and / or a calculator for outputting an alarm is provided, or the wall of the reaction tower, circulation. A heating device is preferably provided in the water pipe or the circulating water pool at the bottom.

Further, according to the present invention, a digestion gas generated by methane-fermenting an organic waste is introduced into the reaction tower filled with a packing material to which microorganisms adhere, after adding air, and water is sprayed. In the method of desulfurizing digestion gas for cleaning and removing hydrogen sulfide contained in the digestion gas, a part of the water to be sprayed is circulated in the reaction tower, and the pH of the circulating water is measured. It is a method for desulfurizing digestive gas, which is characterized by adjusting the supply of fresh water so as to be 6.

In this case, the fresh water and / or the water to be sprayed may be condensed water generated by cooling the digested gas subjected to methane fermentation and / or treated water obtained by dehydrating residual liquid after fermentation. Alternatively, it is preferable to add a chemical that promotes the adhesion of the microorganisms to the fresh water and / or the sprayed water. Furthermore, in the present invention, the oxygen concentration of the digestion gas discharged from the reaction tower is measured, and the amount of the air added before introduction into the reaction tower is automatically adjusted so that the measured value becomes a predetermined target value. At the same time, it is preferable that the concentration of hydrogen sulfide in the digested gas is also measured and the target value of the oxygen concentration is automatically changed according to the measured value. In addition, the flow rate of the digestive gas generated by methane fermentation of the organic waste before introduction into the reaction tower is measured in advance, and a certain proportion of air relative to the measured value is added to the digestive gas. Alternatively, it may be introduced into the reaction tower.

In addition, if any of the above-mentioned digestion gas desulfurization methods is carried out and the voids of the packing material are clogged by the growth of elemental sulfur formed by the oxidation of the microorganisms and / or hydrogen sulfide, Water is filled in the reaction tower to a height higher than the filling height of the packing material, and air is blown from the bottom to float the packing material in the water, and microorganisms and elemental sulfur are separated by the upward flow of air to wash and drain. It is preferable to flow out from the reaction tower. Further, in the present invention, it is preferable to judge the timing of cleaning the voids of the filler by the value of the pressure loss in the reaction tower.

According to the present invention, even if the voids of the filling material are closed, it becomes possible to easily and sufficiently clean them. In addition, by using condensed water from the digestion gas to adjust the pH and widening the operating pH range to 1 to 6,
Not only can it operate without alkali replenishment, but periodic automatic cleaning can achieve a hydrogen sulfide removal rate of 99% or more without cleaning (maintenance) for a long period of one year or more. That is, the digestion gas desulfurization device can be operated with a high sulfur removal rate, a stable treatment, a low cost treatment, and labor saving.

[0019]

BEST MODE FOR CARRYING OUT THE INVENTION Embodiments of the present invention will be described below, including the background of the invention.

First, the inventor has the above-mentioned problem (1).
"Even if the biofilm swells and the voids in the filler block,
We could not solve this problem. " Then, as illustrated in FIG. 1, a digestion gas 1 generated by methane fermentation of organic waste is introduced, and a reaction tower 3 filled with a filler 2 to which microorganisms adhere, and the reaction tower 3
In the digestion gas desulfurization apparatus, which is equipped with an air supply means (blower) 4 for supplying air 15 to the digestion gas 1 before introduction into the digestion gas 1 and a spray nozzle 6 for spraying water 5 onto the digestion gas 1 after introduction from above. The filler 2 to be filled in the reaction tower 3 was not fixed on the perforated plate-shaped support member 7, but simply placed in layers and used. Conventionally, the packing material 2 was washed by pouring water into the reaction tower 3. However, in this way, if the cleaning air 20 is separately blown into the water from below, the packing material 2 easily flows and the biofilm is formed. This is because the peeling of the sulfur and elemental sulfur can be promoted and the cleaning can be sufficiently performed.

Therefore, the inventor diligently studied a suitable filler 2 for causing such a flow, and as shown in an example of the shape in FIG. 2, the specific gravity is 0.9 to 1.05,
In addition, the synthetic resin body 9 having the voids 8 of 80 to 95% in volume ratio is decided. Here, the void 8 refers to a volume portion (gap) not occupied by the resin with respect to the outer shape of the synthetic resin body. If the specific gravity of the filler is less than 0.9, the filler completely floats on the water and cleaning in a short time becomes insufficient.
If it exceeds 05, it will be heavy and will not flow. Also,
The reason why the voids 8 have a volume ratio of 80 to 95% is to increase the surface area to which microorganisms adhere,
A volume ratio of at least 80% is required, and if it exceeds 95%, there is concern about strength and life, so 95% was made the upper limit. The material of the filler 2 may be any kind of synthetic resin, but according to the inventors' trial,
Polypropylene was the most preferred. The amount of the cleaning air 20 blown in is not particularly limited in the present invention. This is because it is sufficient that the filler 2 flows in water. Further, in the present invention, it is preferable that the microorganisms and elemental sulfur separated from the packing material 2 by washing are allowed to flow out from the reaction tower 3 as the drain 10.

In addition, the present inventor also examined the timing of cleaning microorganisms and the like that adhere to the voids 8 of the packing material 2 and block the voids, and check the pressure loss of the digestive gas flowing in the reaction tower 3. I thought about judging by the value. Therefore, in the present invention, as shown in FIG. 1, the sensors 11 and 11 ′ for measuring the pressure loss and the measured value are input to the reaction tower 3, and the differential pressure between 11 and 11 ′ is previously set. When the stored threshold value of the pressure loss is exceeded, a calculator for outputting a signal and / or an alarm for instructing to stop the introduction of the digestion gas into the reaction tower 3 is provided. It should be noted that the threshold may be set to an appropriate value according to past data and test operation. Further, it is preferable that the arithmetic unit outputs a control signal or an alarm to the air supply unit 4, the drain valve, the outflow valve, and the air valve at the bottom of the reaction column according to the value of the pressure loss.

The washing can be performed, for example, by sequentially performing the following operations. 1st stage 2nd stage to stop the inflow of air 15 3rd stage to stop the inflow of digestion gas, close the gas outflow valve 28 while keeping the gas inflow valve 27 open 4th stage to stop the circulating water pump 22 and close the circulating water valve 32 Water is introduced to fill the entire reaction tower 3 with water. The gas remaining therein is pushed out in the direction of the upstream side 1 through the gas inflow valve 27. When the reaction tower 3 is filled with water, the gas inflow valve is closed and the blowoff valve 34 is opened. 7 stages of supplying air and flowing the filler 2 inside to remove biofilm and elemental sulfur accumulated on the surface and voids of the filler After a certain period of time (usually about several minutes), the blowoff valve 3
4 is closed, the gas flow valve 27 is opened, and then the pump 22 is operated, and the separated biofilm and the like are also discharged. When the liquid level in the 8-stage reaction column 3 where the digestion gas is purged is lowered to a certain level (below the packing material 2, normal operation level) through the gas inflow valve 27 as the water is discharged, drainage is performed. Stop, close the circulating water discharge valve 31 and open the circulating water valve 32 Operate the pump 22 and open the gas outflow valve 28 to return to normal processing Next, the above-mentioned problem (2) "lower part of packed bed" In addition, the porous film-shaped support member (eg, screen, net, etc.) 7 that supports the packed bed accumulates the biofilm and the elemental sulfur formed by the oxidization of the removed hydrogen sulfide, and accumulates it frequently. The screen is easily clogged, but it does not flow during cleaning, so cleaning cannot be performed, and in the worst case, operation is stopped. ” Instead of conventional upward flow, It was eliminated in the Rukoto. That is, the digestion gas inlet 13 was provided downward at the top of the reaction tower. This makes it possible to avoid the risk of blockage of the perforated plate-shaped support member 7, which could not be conventionally cleaned. In addition, since the biological film is uniformly formed on all the fillers by the action of the water 5 that is sprayed, and the elemental sulfur that is formed by the reaction is also accumulated in the entire fillers, the filler 2 is effective. Can be used as a result, resulting in less frequent cleaning.

Subsequently, the inventor has found the above problem (3).
We also examined how to eliminate "the amount of alkali injected increases when adjusting the pH of water".

Regarding the problem (3), the inventor has found that the activity of a microorganism that oxidizes hydrogen sulfide in the presence of a trace amount of oxygen is p
It was discovered that H has a sufficient activity even when it is reduced to about 1. Therefore, the activity can be dealt with by allowing the pH of the circulating water to decrease due to the oxidation of hydrogen sulfide and continuing the operation without increasing the pH by adding an alkali. Where p of water
H is continuously measured by installing a pH meter 29 in the circulating water pipe. The measurement position may be appropriately selected before spraying into the reaction tower, after withdrawal from the lower part of the reaction tower, and the like. However,
In order to prevent an extreme decrease in pH, fresh water may be replenished and a part of the circulating water may be replaced appropriately. In this way, not only can you save the cost of alkali chemicals,
It is possible to significantly reduce the speed at which the filler is clogged with scale or elemental sulfur, and to reduce the cleaning frequency of the filler. A water pH meter is installed for continuous measurement. The measurement position may be appropriately selected before spraying into the reaction tower, after withdrawal from the lower part of the reaction tower, or the like. In this case, in order to save water costs and places where it is difficult to obtain fresh water, the digestive gas generated in methane fermentation is cooled naturally or forcibly and the condensed water is condensed. Use or dehydrate digestive juice, water-treat it to remove solids,
It is preferable that the (suspended substance concentration) is 100 mg / liter or less (this is referred to as treated water) before use. Here, the solid content is removed to prevent clogging of the void 8 of the filler. Further, this treated water may be used as water to be sprayed. In addition, new water for replenishment and /
Alternatively, an agent for accelerating the formation of a biofilm in the sprayed water, for example, potassium as an agent for accelerating the activity of microorganisms,
It is desirable to add nutrients containing phosphorus and nitrogen.

Further, the inventor has further described the above problem (4) "the amount of air added to the digestion gas introduced into the reaction tower so that the oxygen concentration of the digestion gas discharged from the reaction tower is at least about 500 ppm. Is adjusted, the oxidative activity of the microorganisms will be reduced and the treatment will be insufficient. ”(5)“ If you try to adjust the oxygen concentration of the digestion gas discharged from the reaction tower to a certain value, the optimum oxygen concentration Is the temperature,
Since it depends on the inflowing gas component, etc., it is not possible to adjust it with high precision. "

The problem (4) is, as shown in FIG. 3, that the oxygen concentration of the digestion gas 1 discharged from the reaction tower 3 is measured by the oxygen concentration meter 16, and the measured value becomes a predetermined target value. As described above, the problem (5) is that the hydrogen sulfide concentration meter 17 measures the hydrogen sulfide concentration at the same time by providing the arithmetic unit 18 that automatically adjusts the amount of air added before introduction into the reaction tower. The target value of the oxygen concentration according to the value
It was solved by automatically changing with. Specifically, the target oxygen concentration of the digestion gas 1 after being treated in the reaction tower 3 (at the outlet of the reaction tower, for example, about 0.5 vol%) is determined in advance, and the reaction tower 3 The amount of air mixed in on the inlet side is controlled by feedback by adjusting the opening of the flow rate control valve 24, and the target value to be set is increased, whereby the digestion gas 1 in the reaction tower 3 is oxidized. Stabilizes. In the present invention, the target oxygen concentration is not particularly limited because it depends on the H ₂ S concentration contained in the digestion gas 1. That is, since the purpose of the desulfurization device is to remove hydrogen sulfide in the first place, the hydrogen sulfide concentration of the digestion gas 1 after being treated in the reaction tower 3 is continuously and automatically measured,
The target oxygen concentration set value was changed based on the numerical value so that stable operation with more optimal accuracy could be performed.

For some reason (in a small-scale plant where a small amount of gas is generated and the gas flow rate is adjusted upstream of the reaction tower, for example, when a gas holder or a gas blower cannot be installed), the inventor enters the reaction tower. We also examined the case where the flow rate of the digestion gas to be introduced fluctuates greatly and it is impossible to adjust it. In this case, the flow rate of the digestion gas may be small, and the feedback control described above may result in a slow response and the hydrogen sulfide concentration may not be successfully reduced. In such a case, as shown in FIG. 4, H _{2 of the} digestion gas 1 measured at the outlet side of the reaction tower 3 is measured.
The S concentration and the oxygen concentration are merely for monitoring, the flow rate of the digestion gas introduced into the reaction tower 3 is continuously measured by the digestion gas flow meter 25, and the air corresponding to a certain ratio (preferably 1 to 4 vol%) is digested. This is also added to the present invention because the feedforward control added to the gas is more accurate. It should be noted that the amount of air added was set in the range of 1 to 4 vol% with respect to the measured value, because if it is less than 1 vol%, the oxidative activity of the microorganisms may be lowered and the oxidative activity of the microorganism may decrease.
This is because the effect cannot be expected to be improved even if it exceeds vol%.

The air flow rate at that time may be controlled by controlling the number of revolutions of the air supply means (blower) 4, adjusting the openings of the discharge valve and the blow-off valve, but the present invention is not limited thereto. Further, the set value of the ratio of the air to be added is preferably adjusted by the H ₂ S concentration and oxygen concentration of the digestion gas at the outlet of the reaction tower.

In addition, in the present invention, in order to carry out the treatment smoothly, it was considered that the temperature of the water circulating in the reaction tower 3 is controlled to be kept at the optimum temperature for the microbial activity. Specifically, it is preferable to keep the temperature of the circulating water at 15 to 40 ° C. As shown in FIG. 1, a heating device 14 (specifically, an electric heater or the like) may be provided in the circulating water pool 26 at the bottom of the reaction tower. The heating device 14 may be provided on the tower wall of the reaction tower 3 or on the circulating water pipe. In addition, the temperature is 15 to 4
The temperature was set to 0 ° C. Below 15 ° C., the activity of microorganisms decreases, so above 40 ° C., there is no change in the activity of microorganisms.
This is because the applied heat is wasted.

[0031]

Example 1 The desulfurization apparatus and the desulfurization method according to the present invention were applied to desulfurize digestive gas generated by subjecting livestock manure to methane fermentation. That is, using the apparatus shown in FIG. 1, 700 m ³ (standard state) / day, hydrogen sulfide concentration of 2000
Digestion gas 1 of up to 3,000 ppm, a filler 2 made of polypropylene shown in FIG. 2 and made of a ribbed hollow disk (specific gravity: 1.0, porosity 85%) having a diameter of 10 cm and a height of 3 cm.
Introducing port 13 provided at the top of the reaction column 3 filled with
Feed more downward. Air added to digestion gas 1 15
Has a target oxygen concentration of 0.
The volume ratio to the digestion gas 1 was adjusted to 1 to 4% so as to be 5 vol%.

The filling height of the packing material in the reaction tower is 2.
The flow velocity of the gas passing therethrough was 25 to 30 m / hr at the superficial velocity, and the digestion gas retention time was 0.1 hour. The water 5 sprayed on the digestion gas 1 is used by adding liquid fertilizer containing nitrogen, phosphorus, and potassium to condensed water generated by cooling the digestion gas, and using an electric heater 14 in a water reservoir provided at the bottom of the reaction tower 3. Water temperature 3
The pH was adjusted to 0 ± 2 ° C., and the pH was adjusted to 5 by supplementing with caustic soda. Further, during the operation, the cleaning timing of the filling material 2 is determined based on the pressure information from the sensor 11 provided in the reaction tower 3, and specifically, the pressure gauge 11
When the pressure difference between ˜11 ′ reached 200 mmAq, the cleaning process was automatically switched to completely prevent the voids 8 of the filler 2 from being clogged with deposits by the pre-cleaning.

Further, as shown in FIG. 3, the H ₂ S concentration of the digestion gas 1 is continuously measured at the outlet side of the reaction tower 3 (H ₂ S concentration meter 1
7), the target oxygen concentration was set based on this value, and the opening degree of the flow control valve 24 was adjusted based on the difference between the target value and the measurement value of the oxygen concentration meter 16. When the gas blower 12 is stopped, the air supply means (blower) 4 is stopped and the arithmetic unit 18 is disabled.

As a result, the hydrogen sulfide content in the digestion gas was 10 ppm or less, which was sufficient to satisfy the target value of 500 ppm or less, and the removal rate of 99% was achieved. Furthermore, the hydrogen sulfide concentration of the processing gas is automatically measured, and the target oxygen concentration is set within the range of 0.05 to 0.5 vol% each time based on the value, making it more stable and with a small residual oxygen concentration. I was able to drive. At this time, the pH of the circulating water is measured before the circulating water is sprayed into the reaction tower, and when the value is below 2.0, fresh water is supplied into the circulating water to supply the circulating water. The pH was controlled at 2.0-2.5.

[0035]

Example 2 In addition, the desulfurization apparatus and the desulfurization method according to the present invention were applied to desulfurize digestive gas generated from a small-scale livestock manure methane fermentation facility. That is, the control system shown in FIG. 4 is attached to the apparatus shown in FIG.
The amount of digestion gas to be processed is 100 m ³ (standard condition) / day,
The H ₂ S concentration was 1000 to 2000 ppm. The other operating methods are the same as those described in the first embodiment. However, the opening degree of the air flow rate adjusting valve 24 shown in FIG.
The flow rate of the air flow meter 23 was set to be X% with respect to the digestion gas flow rate of 25. The X is in the range of 0 to 4 vol% and the H ₂ S concentration of the outlet digestion gas is 17 and the oxygen concentration is 1
Based on the continuous measurement values of 6, the calculator 18 calculates and calculates.

In this methane fermentation facility, the amount of digestive gas flowing into the desulfurization unit fluctuated by ± 50% or more with respect to the average amount, so that the feedback control described with reference to FIG. 3 had a poor response. By performing the feedforward control described in FIG. 4, more reliable control was possible, and the H ₂ S concentration of the processing gas could be stably maintained at 10 ppm or less. The pH of the circulating water at this time is 1.
It was 3 to 1.7.

[0037]

As described above, according to the present invention, it becomes possible to perform desulfurization of digestive gas more easily and efficiently than before in the maintenance of the apparatus and at low cost. As a result, this digestion gas can be effectively used as fuel gas.

[Brief description of drawings]

FIG. 1 is a flow chart illustrating a desulfurization apparatus and a desulfurization method for digestive gas according to the present invention.

FIG. 2 is a perspective view showing a shape of a filler used in the digestion gas desulfurization apparatus according to the present invention.

FIG. 3 is a diagram illustrating feedback control for reducing the H ₂ S concentration of digestion gas in a reaction tower.

FIG. 4 is a diagram illustrating feedforward control for reducing the H ₂ S concentration of digestion gas in a reaction tower.

[Explanation of symbols]

1 Digestion Gas 2 Filler 3 Reaction Tower 4 Air Supply Means (Blower) 5 Water 6 Spray Nozzle 7 Perforated Plate Support Member (Screen etc.) 8 Void 9 Synthetic Resin Body 10 Drain 11, 11 'Sensor (Pressure Gauge etc.) 13 Inlet 14 Heating device 15 Air 16 Oxygen concentration meter 17 H ₂ S concentration meter 18 Computing device 19 Sampling port 20 Cleaning air 21 Chemicals (nutrients) 22 Circulation pump 23 Air flow meter 24 Air flow control valve 25 Digestion gas flow meter 26 Circulating Water Reservoir 27 Gas Inflow Valve 28 Gas Outflow Valve 29 pH Meter 30 Discharge Water 31 Circulating Water Discharge Valve 32 Circulating Water Valve 33 Makeup Water 34 Blowoff Valve

   ─────────────────────────────────────────────────── ─── Continued front page    (72) Inventor Yasuhiko Hashimoto             2-3-2 Uchisaiwaicho, Chiyoda-ku, Tokyo             Saki Steel Co., Ltd. F-term (reference) 4B029 AA05 AA21 BB01 CC02 CC10                 4B065 AC20 BB02 BB40 BC41 BC50                       BD50 CA56                 4D020 AA04 BA23 BC06 BC10 CB13                       CB17 CB25 CC09 DA01 DA02                       DB03 DB04 DB08                 4D059 AA01 BA15 CA07

Claims (11)

[Claims] 1. A reaction tower in which a digestion gas generated by methane fermentation of an organic waste is introduced and a packing material to which microorganisms adhere is filled, and air for supplying air to the digestion gas before introduction into the reaction tower. In a digestive gas desulfurization apparatus including a supply unit and a spray nozzle that sprays water on the digested gas after introduction, the filler has a specific gravity of 0.9 to 1.05 and a volume ratio of 80 to 95. % Of a synthetic resin body having voids, which is filled without being fixed on a perforated plate-shaped support member provided in a reaction tower. 2. The digestion gas desulfurization apparatus according to claim 1, wherein the digestion gas inlet is provided downward at the top of the reaction tower. 3. A sensor for measuring the pressure loss of the digestive gas flowing in the reaction tower, and when the measured value is inputted and exceeds a pre-stored pressure loss threshold value, the digestion gas is sent to the reaction tower. And a computing unit that outputs a signal and / or an alarm for instructing to stop the introduction of the gas.
Alternatively, the digestion gas desulfurization apparatus according to item 2. 4. The desulfurization apparatus for digestive gas according to claim 1, wherein a heating device is provided in the tower wall of the reaction tower, the circulating water pipe, or the circulating water pool at the bottom. 5. A digestion gas generated by methane-fermenting an organic waste into a reaction tower filled with a filler to which microorganisms adhere is introduced after adding air, and water is sprayed to digest the digestion gas. In the method of desulfurization of digestion gas for cleaning and removing hydrogen sulfide contained in, while part of the water to be sprayed is circulated in the reaction tower, the pH of the circulating water is measured so that the pH becomes 1 to 6. In addition, a method for desulfurizing digestive gas, which is characterized by adjusting the supply of fresh water. 6. The fresh water and / or the water to be sprayed,
The desulfurization method of digestive gas according to claim 5, wherein condensed water generated by cooling the digested gas subjected to methane fermentation and / or treated water obtained by dehydrating the residual liquid after fermentation is used. 7. The fresh water and / or the water to be sprayed,
7. The method for desulfurizing digestive gas according to claim 5, wherein a chemical that promotes adhesion of the microorganisms is added. 8. The oxygen concentration of the digestion gas discharged from the reaction tower is measured, and the amount of the air added before introduction into the reaction tower is automatically adjusted so that the measured value becomes a predetermined target value. At the same time, the hydrogen sulfide concentration of the digestion gas is also measured, and the target value of the oxygen concentration is automatically changed according to the measured value, and the digestion according to any one of claims 5 to 7. Gas desulfurization method. 9. The flow rate of digestive gas generated by methane fermentation of the organic waste before being introduced into the reaction tower is measured in advance,
The desulfurization method of a digestive gas according to any one of claims 5 to 7, wherein air having a fixed ratio to the measured value is added to the digestive gas and then introduced into the reaction tower. 10. The method for desulfurizing digestive gas according to any one of claims 5 to 9, wherein pores of the filler are blocked by growth of elemental sulfur formed by oxidation of the microorganisms and / or hydrogen sulfide. Then, water is poured into the reaction tower to a height not less than the filling height of the packing material, air is blown from the lower part to float the packing material in water, and microorganisms and elemental sulfur are separated by the rising flow of air to wash. The drainage gas desulfurization method according to any one of claims 5 to 9, wherein the drainage gas is discharged as drain from the reaction tower. 11. The method for desulfurizing a digestive gas according to claim 10, wherein the timing of cleaning the packing material is determined by the value of the pressure loss in the reaction tower.