JP5531235B2 - Biomass continuous dry gasification plant - Google Patents

Description

  The present invention is a continuous biomass dry gas that is recycled as a raw material in principle without producing a processing residue when anaerobic methane fermentation is performed on biomass with a high water content, such as raw garbage and organic waste, to recover flammable gas. Relates to chemical plant.

  Conventionally, the treatment of fluid biological waste such as livestock excreta has been performed by anaerobic fermentation with the help of methane bacteria, and the generated gas has been used as fuel and the fermentation residue as fertilizer. An anaerobic environment is required for methane fermentation, and the environment is realized by a wet method (or water seal type) that blocks oxygen by immersing the material in a large amount of water. In this case, since a mixture of fermentation residue and water is obtained, it is convenient if there is a condition that can be used as liquid fertilizer as it is. However, in an environment where liquid fertilizer is not used, solid-liquid separation and water treatment are required.

  One of the inventors of the present application is anaerobic fermentation in which anaerobic fermentation is performed by anaerobically fermenting the anaerobic fermentation residue directly connected to the anaerobic fermentation tank that recovers combustible gas by anaerobic methane fermentation of the raw material biomass. We proposed a continuous dry biomass gasification plant with a tank placed in the latter stage and received a patent in 2009 (Patent Document 1). The present invention corresponds to an improvement plan for the patented invention.

  According to the above-mentioned patented invention, the risk of generating anaerobic reaction mass in an aerobic environment is eliminated, safe operation is ensured, there is no need to water seal the raw material biomass, so dehydration and waste liquid treatment of anaerobic fermentation residue, As a result, field treatment for that purpose is no longer necessary, and the adverse effects of air, water, and noise on the plant periphery can be minimized.

  Patent Document 2 discloses a method of drying raw material biomass before charging an anaerobic fermenter using aerobic fermentation. In this method, the raw material biomass is once dried to a moisture content of about 2% using an aerobic fermentation process ([0051]), and then immersed in a liquid anaerobic fermentation medium (methane fermentation) ([0040]). . Further, it is described that the fermentation residue in the thermophilic microorganism treatment tank is sent to a wastewater treatment facility such as an activated sludge tank for treatment ([0029]). From these descriptions, the invention of Patent Document 2 is considered to be different in technical idea from the above-described patented invention and the following present invention.

  Patent Document 3 discloses that methane gas is recovered in a tunnel-type methane fermentation section after the moisture of raw material biomass is evaporated by the fermentation heat of aerobic fermentation and the water content is reduced from about 80% to about 55%. Disclosed is a method for taking out as compost. In this method, the raw material biomass after moisture transpiration is in principle supplied to methane fermentation, and the methane fermentation residue is taken out of the system as compost in principle. Seem.

Japanese Patent No. 4346035 JP 2004-358400 A Japanese Patent No. 4114169

  In order to efficiently methanate raw material biomass whose moisture content may exceed 85 wt% by anaerobic fermentation, it is necessary to adjust the moisture content in the anaerobic fermenter to 70 wt% or less. ) Adopts a method in which fermentation is completed in an aerobic fermenter downstream of the anaerobic fermenter and a part of the product whose water content has dropped to about 30 wt% is returned to the anaerobic fermenter entrance (the rest is supplied externally as compost). did. However, this method may require a reflux amount equivalent to 60% of the raw material biomass on a weight basis, which increases the amount of processing, increases the overall size of the apparatus, and increases the operation power.

  Therefore, the main problem to be solved by the present invention is to propose a treatment method that can eliminate the above-mentioned reflux for adjusting the moisture content, and an apparatus structure suitable for the treatment method.

  As a means for dehydrating, drying, and heating the raw material biomass, an aerobic fermentation drying tank is disposed immediately before the anaerobic fermentation tank.

  The position of the above-mentioned patented invention was in co-production of compost and combustible gas. However, the demand for compost depends on the location of the plant and is not always stable.

  On the other hand, an aerobic fermenter has a function of dehydrating, drying and heating while supplying oxygen by blowing hot air into the raw material biomass in order to adjust the fermentation conditions. However, even if there is no demand for compost and production is not performed, the dehydration, drying and heating functions of this aerobic fermenter are never wasted. This is because if this function is utilized, the moisture content of biomass can be directly controlled without relying on the means of reflux adopted in the above-mentioned patented invention. For this purpose, the role of the aerobic fermentation tank is reviewed, and in some cases, it can be placed just before the anaerobic fermentation tank as an aerobic fermentation drying tank that can also perform aerobic fermentation. Thus, the above-mentioned means for solving the problem has been conceived.

  However, when reviewing the role of the aerobic fermentation tank as described above as an aerobic fermentation drying tank as described above, the drying function that has been somewhat conservative has been drastically enhanced so as not to adversely affect the aerobic fermentation bacteria. It is desirable to make it easier. This is a secondary solution to the present invention.

  A solution to the above-mentioned secondary problem is to arrange a large number of stirring paddles that crawl the contents of the tank and spray them into the tank from the inner surface of the aerobic fermentation drying tank having a rotating drum shape. .

  According to the present invention, it is not necessary to recirculate dry biomass to the anaerobic fermenter entrance, and the amount of processing is suppressed, so that the process equipment is compact and energy efficiency is improved.

  Furthermore, by installing the stirring paddle in the aerobic fermentation drying tank, the moisture transpiration effect of hot air is improved, and the time for reducing the moisture content to a predetermined value can be shortened. Can be shortened than before.

  Embodiment 1: A pulverized mixing and feeding apparatus for pulverizing and mixing raw material biomass and continuously taking it into the system, and a barrel part rotatably supported by chambers at both ends, mechanically sealed from outside air, and stirring means and hot air A horizontal rotating drum type aerobic fermentation drying tank provided with a forced aeration means connected to the generating means, a transfer machine for continuously transferring the discharge from the outlet of the aerobic fermentation drying tank to the anaerobic fermentation tank, and the body A horizontal rotating drum type anaerobic fermenter that is rotatably supported by the chambers at both ends and mechanically sealed from the outside and equipped with stirring means and a hollow heat exchange pipe, and fermentation residue is continuously discharged from the anaerobic fermenter. In a continuous biomass dry gasification plant comprising a cutting machine that operates, when there is a demand for compost, the aerobic fermenter is operated as usual, and part or all of the output is supplied outside the system, If there is a residue To introduce into the gas fermentation tank.

  Embodiment 2: Conversely, when there is no demand for compost, an aerobic fermenter is exclusively used as a dehydrating / drying / heating device. In this case, the methane gas yield in anaerobic fermentation increases as much as the principle amount of biomass is devoted to gasification, because the weight loss of aerobic fermentation is suppressed (the weight loss is not zero due to natural fermentation).

  Embodiment 3: In an anaerobic fermentation tank, the water content gradually increases and reaches the maximum water content at the tank outlet. Therefore, the dehydration, drying, and heating functions of the aerobic fermenter are used. That is, the fermentation residue is taken out from the anaerobic fermenter, returned to the aerobic fermentation tank, and dehydrated and dried. In this way, it is possible to treat the anaerobic fermentation residue without touching the outside air, and to avoid the field treatment of the dehydrated waste liquid accompanied by the malodor problem. At the same time, since the anaerobic fermentation residue is not discharged outside the system, it is again used for gasification, so that the whole amount of raw material biomass can be gasified in principle.

  Embodiment 4: The aerobic fermenter includes a forced air blower that promotes evaporation of surplus moisture together with oxygen supply to the tank and a hot air generator by heat exchange between gas power generation (cogeneration) waste heat, and in the aerobic fermenter The warmed air and water vapor are collected and supplied to the hollow fixed shaft provided in the anaerobic fermenter, and the contents of the anaerobic fermenter are indirectly heated and then released to the atmosphere from the end of the hollow fixed shaft through the deodorizer.

  FIG. 1 is a simplified block diagram illustrating a processing flow according to an embodiment of the present invention. The accepted garbage is put into the aerobic fermentation drying tank together with the recycled anaerobic fermentation residue, and the water is evaporated and dried. Biomass whose water content has been reduced to a predetermined value is transferred to an anaerobic fermenter, methane-fermented, and partly converted into methane gas. Methane gas is supplied as fuel to the cogeneration system to generate electricity and waste heat.

  FIG. 2 is a diagram in which the material balance is shown in the processing flow. In the figure, the numbers (kg / day) in the boxes for "New raw material", "Anaerobic residue", "Aerobic fermentation drying", "Transfer", "Aerobic fermentation", and "Heat and transpiration" are shown in order from the top. In the total processing amount, wt (water content), and ds (dry solid amount) in the block, the total processing amount = water amount + dry solid amount. The material balance of this figure is made on the assumption that the amount of compost discharged from the aerobic fermenter to the outside is zero. These numerical values assume a steady operation state and do not include an unsteady state at the beginning of operation.

First, a total of 660 kg of biomass, which is 516.3 kg of raw food waste and 143.7 kg of anaerobic residue, is put into the aerobic fermentation and drying tank, and the water content is reduced from 561 kg to 97.8 kg by 463.2 kg. However, due to carbon dioxide generation by aerobic fermentation, it decreases by 19 kg from 99 kg to 80 kg (the value of the decrease appears in the “Fever / Transpiration” box). The residence time of the biomass in the aerobic fermentation drying tank is 7 days, the dimensions of the aerobic fermentation drying tank are φ1.4 m × L4.3 m → 6.6 m ³ , and the power consumption is 0.4 kw. Waste heat of 1,959kcal is supplied from the cogeneration unit to make hot air for drying to blow into the tank.

  As a result, as shown in the “Transfer” box, the treated amount 177.8 kg = water content 97.8 kg + dry matter amount 80.0 kg is transferred to the anaerobic fermenter. At this time, the moisture content is 55 wt%, and the power for transfer is 0.1 kw.

In an anaerobic fermenter, the amount of dry matter is reduced by 34.1 kg from 80.0 kg to 45.9 kg. This decrease is methane gasification and appears in the generated gas quantity box. However, the moisture content does not change in the anaerobic fermenter, so the moisture content increases with the decrease in the amount of dry solids, and the maximum value is 68 wt% at the outlet of the anaerobic fermenter. These are returned to the aerobic fermentation drying tank as anaerobic residue, and dehydrated and dried. The size of the anaerobic fermentation drying tank is φ1.4m × L3.0m → 4.6m ³ , and the power consumption is 0.4kw.

  The hot air for drying sent to the aerobic fermentation and drying tank is in the anaerobic fermentation tank with 463.2 kg of water (water vapor) and carbon dioxide equivalent to 19.0 kg of dry matter as shown in the “Heat / Transpiration” box. After the contents of the anaerobic fermenter are indirectly heated, they are discharged from the end of the hollow fixed shaft through the deodorizer. The power for the deodorizer is 0.4 kw.

  As seen above, anaerobic fermenters convert 34.1 kg of dry matter into methane gas. This methane gas is supplied to the cogeneration unit via the desulfurization unit, generating 10kw of electricity and 14,000kcal of waste heat. Since the power consumed by this system is 1.7kw and the waste heat is 1,959kcal, 8.3kw of power and approximately 12,000kcal of waste heat can be supplied outside the system.

  FIG. 3 is a conceptual elevation showing the schematic structure of the aerobic fermentation drying tank and the anaerobic fermentation tank shown in the processing flow of FIG.

  Both the aerobic fermentation drying tank and the anaerobic fermentation tank are mechanically sealed from outside air by rotatably supporting the body (3) in both the inlet and outlet chambers (1, 2), and stirring means and It consists of a horizontal rotating drum with a central fixed shaft. The two tanks are connected by a transfer machine (9) sealed from the outside air. In addition, a cutting machine (10) for discharging the fermentation residue is installed at the anaerobic fermentation tank outlet, from which the anaerobic fermentation tank residue is recycled to the aerobic fermentation drying tank. In addition, in this figure, illustration of the ventilation blower and hot-air generator in an aerobic fermentation drying tank, the gas holder in an anaerobic fermentation tank, and other attachment apparatus was abbreviate | omitted.

  Both tanks have two types of stirring means inside. The first stirring means is a feed blade (7) for propelling and moving the contents of the tank toward the outlet. A number of feed blades (7) are arranged in a spiral pattern on the inner wall of the tank, and each blade propels and conveys the contents toward the tank outlet as the tank rotates. Note that fixed agitating blades (5) that cross in a cross shape are attached to the fixed shaft (4) at regular intervals, and the tank contents are agitated against the propulsive force of the feeding blade (7).

  The second stirring means is a stirring auxiliary blade (6) that scoops up the contents with the rotation of the tank and sprays the contents into the tank. The auxiliary stirring blades (6) are arranged upright in a row parallel to the central axis of the tank at each of the upper, lower, left and right positions of the inner wall of the tank. By the 2nd stirring means in an aerobic fermentation drying tank, the contact with the hot air blown in and the tank content becomes favorable, and a water | moisture-content transpiration | evaporation efficiency improves. Biomass mass during anaerobic fermentation is crushed by the second stirring means in the anaerobic fermenter to improve gas diffusibility, preventing the accompanying of flammable gas to the anaerobic fermentation residue and improving safety. .

  The present invention contributes to the development of various industries that emit garbage and organic waste, especially agriculture, fisheries, livestock, food processing, sales distribution, etc., and contributes to the activities of local governments that handle garbage can do.

It is a block diagram which shows the processing flow in the biomass continuous dry-type gasification plant which concerns on one Example of this invention. It is the block diagram which combined the material balance with the process flow in the biomass continuous dry gasification plant which concerns on one Example of this invention. It is a conceptual elevation which shows the structure of the aerobic fermentation drying tank and the anaerobic fermentation tank which concern on one Example of this invention.

1: Inlet chamber 2: Outlet chamber 3: Rotating drum 4: Fixed shaft 5: Fixed agitating blade 6: Agitating auxiliary blade 7: Feeding blade 8: Loading port 9: Transfer machine 10: Cutting machine

Claims (2)

In a continuous biomass dry gasification plant that collects combustible gases such as methane by subjecting raw material biomass to anaerobic fermentation,
Is rotatably supported the barrel into the chamber at both ends are sealed from mechanically outside air, and equipped with a stirrer hand stage, Yoko置rotation equipped with forced ventilation means being further connected to the hot-air generating means and the heat air generating means A drum-type aerobic fermentation drying tank;
And NyuSo location feed grinding and mixing continuously incorporated into該好gas fermentation drying tank the raw biomass pulverized and mixed to,
And Yoko置rotary drum anaerobic fermenters is sealed from mechanically outside air, and with a hollow stationary shaft having an agitation hand stage and heat exchange function is rotatably supported the barrel into the chamber at both ends,
A transfer machine for continuously transferring the discharge from the outlet of the aerobic fermentation drying tank to the anaerobic fermentation tank;
Comprising a cutting machine for continuously discharging the fermented residue from the anaerobic fermentation tank,
The aerobic fermentation drying tank and the anaerobic fermentation tank are each provided with two types of stirring means, and the first type of stirring means has a plurality of blades arranged in a spiral curve on the inner wall of the tank, and each blade The second type of agitation means has a number of blades parallel to the central axis of the tank at each of the upper, lower, left and right positions of the inner wall of the tank. Are arranged in a row, and the contents are scooped up and sprayed into the tank as the tank rotates,
As a means for dewatering, drying and heating the biomass, the aerobic fermentation drying chamber is arranged immediately before the anaerobic fermentation tank, recycling the anaerobic fermentation residue taken out from the anaerobic fermentation tank outlet to said aerobic fermentation drying tank Then, the gasification plant is again subjected to methane gasification.   The gasification plant according to claim 1, wherein the aerobic fermentation drying tank is capable of producing compost by subjecting the contents to aerobic fermentation as desired.

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