JPH08120287A - Molded fuel, and process and apparatus for producing same - Google Patents

Abstract

PURPOSE: To obtain a molded fuel which enables the effective utilization of waste materials and contributes to the protection of the global environment by using a shell powder and algae obtainable in the neighborhood of a thermal power plant. CONSTITUTION: The molded fuel contains a coal powder, a shall powder as a desulfurizing agent, and algae, is produced by mixing a coal powder, a shell powder obtd. by subjecting shells collected in the neighborhood of a thermal power plant to aerobic fermentation to decompose and eliminate org. substances, and cultured algae obtd. by fixing CO2 contained in the exhaust gas of the plant to algae by photosynthesis, and is pref. a mixture comprising 40-75wt.% coal powder, 5-20wt.% shell powder, and 10-40wt.% algae (on dry basis). A coal powder of 50-200 mesh, a shell powder of 50-200 mesh, and dehydrated algae as such are used. Shells discarded in culturing, food processing, eating, etc., can also be used.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a molded body fuel that uses raw materials that can be procured in the vicinity of a thermal power plant, can effectively use waste, and at the same time contributes to preservation of the global environment, a method for producing the same, and a molded body. The present invention relates to a fuel manufacturing device. More specifically, the present invention uses a coal as a raw material, uses shell powder as a desulfurizing agent, and uses molded algae obtained by immobilizing CO ₂ in exhaust gas by photosynthesis of algae, a molded body fuel, a manufacturing method and a manufacturing apparatus thereof. Regarding

[0002]

2. Description of the Related Art The amount of energy used in the world has been increasing more and more in recent years, and the depletion of energy sources has been highlighted as a problem in the near future. Under such circumstances, the utility value of coal as a fuel has recently been reviewed, and coal powder, coal fuel in the form of slurry and briquette have been used in combustion furnaces for thermal power generation and incinerators.

At the same time, the problem of environmental pollution has come to be widely taken up, and environmental pollution due to SO ₂ contained in coal combustion exhaust gas and global warming due to CO _{2 have become} a global problem, and they have become a problem in the atmosphere. Emissions control and emission control are becoming real issues. To solve such energy problems and environmental problems at the same time,
A composite solid fuel in which plant materials such as wood debris and straw are added to coal to improve combustibility, and slaked lime is further added as a desulfurizing agent, and molasses is further mixed as a binding agent has been already disclosed (Japanese Patent Laid-Open No. 6-58242). -80974). Also disclosed is a solid fuel in which carbonaceous fuel is mixed with slaked lime or calcium carbonate as a desulfurizing agent and an ammonium compound as a desulfurizing agent at low temperature (Japanese Patent Laid-Open No. 105889/1993).
Issue).

[0004]

However, plant materials such as wood, straw, and bagasse mixed with coal have problems in locality, time, and regular arrival, and the collection cost cannot be ignored.
In addition, since coal contains much more sulfur than petroleum than petroleum, a large amount of sulfur oxide is generated in the combustion exhaust gas, and slaked lime is used in the conventional method as a desulfurizing agent for preventing environmental pollution due to these, Calcium carbonate or the like is added to the coal raw material or is dropped in the furnace. However, the cost of the desulfurizing agent is so high that it cannot be ignored, and cornstarch, molasses, tar, heavy oil, etc., which is added as a binder for forming a suitable shape such as a briquette, are also available. Is also pushing up manufacturing costs.

By the way, various shellfish adhere to the cooling water intake and outlet of the thermal power plant, especially around the intake because they interfere with the intake of the cooling water and cause a failure of the generator. There is the fact that the shellfish that are collected and discarded are either landfilled or are simply disposed of as waste by paying a disposal fee to the waste disposal companies. This waste gives off a foul odor during transportation and drips water, which is a source of complaints from the local residents. In addition, even if the landfill treatment is carried out, there is no surplus in the treatment site, and eventually it was necessary to consider self-contained treatment within the power plant.

The present inventors have noted the fact that about 75% of this shell is calcium carbonate. If this shellfish can be effectively used as a desulfurizing agent without being discarded, it can solve the waste disposal problem and at the same time become a promising calcium carbonate source. Further, in recent years, from the viewpoint of prevention of global warming, it has been a subject to reduce carbon dioxide gas in exhaust gas as much as possible, and it is a matter of time before the total amount of carbon dioxide gas is regulated. Therefore, various methods for removing carbon dioxide are being researched on a global scale. Among them, carbon dioxide is fixed by photosynthesis in plants and converted into oxygen, and algae are about 10 times as much as forests. Since it has the ability to fix carbon dioxide, the method of fixing carbon dioxide in exhaust gas by photosynthesis by algae is almost established as one of the effective methods of removing carbon dioxide.

However, although the immobilization method by photosynthesis is effective as a carbon dioxide removal method, for example, in the case of a thermal power plant of 500,000 kilowatts, thousands of tons of cultured algae can be obtained as biomass, and this time the algae disposal I was in trouble. Various treatment methods for these cultured algae have been studied, but it has been found that incineration is the most advantageous in terms of cost. However, since incineration is inconsistent with the intention of reducing carbon dioxide, some convenient treatment method was sought.

The present inventors have noted the fact that the biomass produced by this photosynthetic culture is conveniently a powerful fuel source containing 50% carbon per dry weight and is excellent in ignitability. The excellent ignitability can suppress the generation of unburned carbon of coal in a low temperature range, and thus can be used as a combustion improver for coal. Moreover, since algae contain sugars and proteins in addition to carbonaceous material, the algae themselves can also serve as a binder, which may contribute to cost reduction.

If the calcium carbonate contained in the recovered shell is utilized as a desulfurizing agent, the cultured algae obtained by photosynthesis of algae are used as a combustion improver, and these are used as coal easily available at a thermal power plant. It was found that if mixed and molded into fuel, it is possible to produce a high-performance fuel from raw materials that are easily available at the same site of the thermal power plant and its periphery, and also reduce the cost of the desulfurizing agent and the combustion improver itself. It was In particular, it has high industrial utility in that it can achieve pollution prevention and environmental measures in the vicinity of a thermal power plant, which is a central exhaust source, in a self-contained cycle, and also can collect and reuse waste and effectively use resources. .

[0010]

SUMMARY OF THE INVENTION The present invention therefore provides a green fuel containing coal powder, shell powder as a desulfurizing agent, and algae. In particular, the shell powder is a shell powder obtained by aerobically fermenting shellfish collected from around the intake and / or drain of a thermal power plant to decompose and remove organic matter, and the algae are exhaust gas from the thermal power plant. The molded body fuel, which is a cultured alga obtained by photosynthetically immobilizing CO ₂ in the alga, is preferable. Until now, there has been no example of using shell powder as a desulfurizing agent.

The present invention further includes coal powder, shell powder obtained by aerobically fermenting shellfish collected from the periphery of a thermal power plant to decompose and remove organic matter, and CO ₂ in exhaust gas of the thermal power plant. Also provided is a method for producing a molded body fuel, which comprises mixing with a cultured algae obtained by immobilizing algae on photosynthesis and molding the mixture. In the present invention, the shell powder may also contain shellfish powder collected around the intake and / or drain of large-scale factories other than thermal power plants, and other shell powder discarded in aquaculture, food processing, meals and the like. In addition to the algae, other plant matter, for example, a pulverized product of a wood-based substance can be contained.

The invention also relates to a device for producing the above-mentioned shaped body fuel. That is, the present invention is a coal crushing device, a device for aerobically fermenting recovered shellfish, a device for recovering shells from the fermentation device, a device for crushing the recovered shell, a photosynthetic bioreactor device for algae, and cultured algae. A mixing device for mixing the powder from the coal crushing device, the shell powder from the shell crushing device, and the separated cultured algae, and a mixture from the mixing device. The present invention also relates to an apparatus for producing a molded body fuel, including the forming apparatus for

The algae contained in the molded fuel according to the present invention contains not only carbonaceous matter but also sugars, proteins and some water, so that the algae itself is a combustion improver and also a caking agent. It serves as an agent and can contribute to cost reduction without the need to add a binder separately. Hereinafter, the present invention will be described in more detail.

The green fuel according to the present invention comprises coal powder of 40%.
-75 wt%, preferably 55-65 wt%, the desulfurizing agent 5-20 wt%, preferably 8-12 wt%, and the cultured algae as a dried product 10-40 wt%, preferably 15-30 wt% It is preferable to mix them at a ratio such that The coal powder used according to the present invention is 50
~ 200 mesh, preferably 80-150 mesh,
Particularly, about 100 mesh is preferable. Also, the shell powder is 5
It is 0 to 200 mesh, preferably 80 to 150 mesh, especially around 100 mesh, and since the algae are fine themselves, they can be sufficiently used as they are as long as they are dehydrated without crushing.

The coal may be loaded in a mixing device after crushing coal loaded in a coal yard of a thermal power plant. As the pulverizer, any suitable coal pulverizer such as a ball mill type such as a rolling ball mill, a vibrating ball mill, a planetary mill, or a stirring mill type such as a screw type may be used. Rolling ball mills are most preferred. The shellfish, which is the raw material of the desulfurization agent, is the wall around the cooling water intake and drain of the thermal power plant,
Shellfish attached to fences and the like, and examples thereof include barnacles, husks, mollusks such as blue mussels, and the like.
The most common and large-scale collection is the mussel. Usually, the body is attached to these, and it is preferable to separate and dry only the shells for use, but it is also possible to use after pulverizing after drying even with a small amount of the body attached.

In order to remove the body from the shell and recover only the shell, the shells are washed to remove almost any attached sand and the like, and then organic matter is decomposed and removed by wet aerobic fermentation. Wet aerobic fermentation can be operated continuously or batchwise, cylindrical type,
In a fermenter such as a box type, various bacteria such as Bacillus, Zoogloea, Candida, and Pseudomonas as bacteria.
s), and as a ciliate, Vorticella
, Opelcularia (Opercularia), etc., soaked in a fermented liquor containing at least one of them, and atmospheric aeration of 0.01 ~
Fermentation is carried out at 1 vvm, temperature 15-45 ° C., usually room temperature for about 2 weeks to 2 months, usually 1 month.

After the fermentation is completed, the organic substance dissolves and disappears, and almost only the shell remains. Therefore, the shell is taken out from the fermenter, drained, optionally dried with hot air at 100 to 200 ° C., and then ground to a predetermined fineness. Then add to the mixing device.
The hot air drying may use the residual heat of the power plant and does not require new energy. For crushing shells, a ball mill type such as a rolling ball mill, a vibrating ball mill, a planetary mill, or a stirring mill type such as a screw type mill can be used as appropriate, and the rolling ball mill is preferable.

Since the fermenting bacteria remain in the fermented liquid after draining, it can be recycled without being discarded or introduced into the photosynthetic bioreactor reaction tank described later to reduce the amount of water released into the environment. . Also, since the exhaust from the wet aerobic fermentation tank has a strong odor, it may be exhausted through a deodorizing device, but since this exhaust contains carbon dioxide, it is introduced into the photosynthetic bioreactor reaction tank to purify the carbon dioxide and simultaneously deodorize it. After that, it is more convenient to exhaust.

The shell powder thus obtained contains about 75% calcium carbonate and also phosphorus, potassium and the like, but the whole shell powder can be used as it is as a desulfurizing agent without separating and purifying them. The present invention is the first time that the shell powder is used as the desulfurizing agent, and it is an unexpected and valuable invention for those skilled in the art that the raw material can be obtained at low cost and the waste can be effectively used.

As a desulfurizing agent, in addition to the above-mentioned shell powder,
Other recovered shellfish, shell powder that is discarded during aquaculture, food processing, meals, etc. can also be used. Therefore, it can also contribute to the disposal of a large amount of shells that are discarded after they are taken out from the shellfish production area. Although various kinds of algae can be used in the molded fuel of the present invention, cultured algae obtained by photosynthetically immobilizing CO _{2 in} the exhaust gas of a thermal power plant to algae are preferable. The photosynthesis refers to a reaction in which a plant synthesizes a carbohydrate from carbon dioxide and water in the presence of light. Examples of algae that can be used for photosynthesis in the method for producing a molded body fuel of the present invention include microalgae that are easily available and easy to handle, and can be used as they are without being particularly pulverized if dried, for example, having a size of 2 to 10 microns. Preferred are, for example, cyanobacterium Spirulina, green alga Chlorella, and the like. The green alga Chlorella is preferred.

The photosynthetic apparatus for algae may be of any type as long as it can photosynthesize algae, but an internal irradiation type optical fiber introduction type photosynthetic bioreactor capable of allowing light to penetrate into the apparatus is preferable. The photosynthetic bioreactor may have any shape such as a cylindrical shape or a box shape, and exhaust gas is introduced from below the bioreactor device to absorb CO ₂ . When the CO ₂ absorption rate is low, the CO ₂ absorption rate can be further increased by returning the exhaust gas from the bioreactor device to the reactor device and recirculating it.

The algae have a suitable concentration in the bioreactor,
It is preferably suspended at a concentration of 0.5 to 2.0 g / L.
Exhaust gas from a thermal power plant has a CO ₂ concentration of around 20% and a temperature of around 60 ° C., so when introduced into a bioreactor, it produces a moderate temperature, and CO ₂ due to algae
It can be suitably used for fixing. As the photosynthesis conditions, under atmospheric pressure, exhaust gas ventilation of 0.01 to 1 vvm, using sunlight and artificial light (100 to 1000 μE / m ² s) such as a metal halide lamp, a xenon lamp, and a fluorescent lamp, Light can be introduced into the bioreactor by using an optical fiber made of quartz glass or plastic. It is grown by photosynthetic culture at a culture temperature of 10 to 60 ° C, preferably 20 to 40 ° C. Since the culture temperature can be sufficiently covered by the heat content produced by the residual heat of the exhaust gas, new energy is not required.

The grown algae are continuously or intermittently taken out from the bioreactor as appropriate, separated and dehydrated from the culture mother liquor by a separator, and washing water is added several times in order to remove salt in the culture broth mixed with the algae. After repeating the dehydration operation, the final water content is 20 to 70%, preferably 40 to 6
Dehydrate to 0%. This product can be introduced into the mixing device as it is because it contains water that is suitable for the production of molded fuel, but in some cases it is dried with hot air of 100 to 200 ° C., further pulverized to a predetermined fineness, and then introduced into the mixing device. You can also The hot air drying may use the residual heat of the power plant and does not require new energy.

As a separator for cultured algae, a centrifugal separation type,
Various types such as a filter press type can be used, and a centrifugal separation type is convenient. The mother liquor after the separation of algae can be recycled and reused in a photosynthetic bioreactor or a wet aerobic fermenter. Since the bioreactor can be operated continuously, once started, it can be operated for a long time by automatic operation. The algae thus obtained contain about 50% carbon by dry weight,
Not only can it serve as a carbon source, but it can enhance the in-furnace ignitability in the low temperature range of 500 to 700 ° C.
It is a combustion improver that can prevent the incomplete combustion of coal and generation of unburned carbon, and is also useful as a binder for forming a molded body.

In addition to algae, the molded fuel of the present invention can also contain pulverized products of wood-based substances such as thinned wood and wood-based coarse dust. The coal powder obtained as described above, the desulfurizing agent, and the cultured algae are put into a mixing device in any order and mixed, and then the mixture is mixed with a conventional molding device conventionally used in the art, for example, Otsuka Iron Works K14
It is installed in a type 4 or high-pressure briquette manufacturing machine and the temperature is 20
~ 100 ° C, preferably 1 ~ 4t / cm ² at 40 ~ 80 ° C
Mold under pressure to form a proper shape. The shape of the molded fuel has a length of 20 to 50 mm × 20 to 50 mm and a thickness of 20 in view of the purpose of use as a fuel and the ease of handling.
Granules or briquettes of about mm are good, 40 × 35 × 20 mm
A granular form is suitable.

[0026]

【Example】

Example 1 The present invention will be further described with reference to the flow chart of FIG. 1 showing an example of the manufacturing process and apparatus of the molded body fuel of the present invention. Coal was ground to 100 mesh in a rolling ball mill.

Separately from this, after the attached shells collected by a robot from around the intake and drain of the power plant are washed in the washing tank 1, as bacteria, Bacillus, Zoogloea, Candida, and Pseudomonas, and as ciliates Vorticella, Opercularia
The mixture was fed to a box-shaped air-introduced open wet aerobic fermentation apparatus 2 (capacity 1.5 m ³ ) containing 1 m ³ of the culture solution containing the mixture of ³ ) by a screw conveyor 3A. Fermentation liquid temperature was maintained around 30 ° C., and aerobically fermented under atmospheric pressure while introducing air from a blower at an air flow rate of 1.0 vvm. After one month, only a small amount of fibrous material remained, and the shellfish were almost dissolved and disappeared. The shells were transferred to the water washing / draining conveyor 4 by the screw conveyor 3B, washed, drained, and pulverized to 100 mesh in the rolling ball mill pulverizer 5. The fermented liquid collected in the drainage water receiving tank 12 was circulated to the wet aerobic fermentation device 2 or the photosynthetic bioreactor 6 for reuse.

Light collecting device 7 and plate shape (30 mm ×
Photosynthesis bioreactor 6 equipped with plastic optical fiber irradiation plate 8 for internal irradiation (10 mm × 60 mm)
A culture solution (5% CO ₂ per day of CO ₂ 200 g / m ³ ) in which green alga Chlorella was suspended at a concentration of 1.0 g / L (5
0 liter), and the exhaust gas from the thermal power plant (temperature of about 60 ° C., containing about 20% of CO ₂ ) has an air flow rate of 0.5 vv.
Introduced in m. The liquid temperature is about 25 due to the temperature of the exhaust gas.
It was kept at ~ 30 ° C. Sunlight is introduced into this bioreactor during the day and fluorescent lights (100-1
000 μE / m ² s) and using sunlight and fluorescent light together,
Photosynthesis was performed under atmospheric pressure.

The concentration of chlorella was observed with time, and about 2.
If it exceeds 5 g / L, the content of the reactor is 0.6 per hour.
L is taken out, and the culture solution and the cultured algae are separated by a centrifugal dehydrator 9, and at the same time, water washing is repeated several times to obtain a water content of 50.
It was dehydrated until it became a percentage. Exhaust gas discharged from the bioreactor above still has a CO ₂ contained about 19%, it was recycled to the bioreactor.

65 parts by weight of the crushed coal, 10 crushed shells
Mixing unit 10 parts by weight and 25 parts by weight of culture chlorella
Introduced into the high temperature briquette device 11 made by Otsuka Tekko Co., Ltd.
Under a pressure of ton / cm ² , a granulated briquette compact of 40 × 40 × 20 mm was formed. The briquette compact thus obtained was subjected to a combustion experiment by comparing it with a conventional solid fuel containing calcium hydroxide as a desulfurizing agent, and the sulfur content in the obtained ash was analyzed to compare the immobilized sulfur content. . Conventional solid fuel has a Ca / S molar ratio of 1-2 and an immobilization rate of 60.
˜80%, whereas the briquette compact of the present invention showed an immobilization rate of 75 to 85% at the same molar ratio. It is considered that this is because, in addition to calcium carbonate, which is the main component of the shell, a trace amount of metal components contained in the shell exerted an effect of promoting the immobilization of sulfur content. Example 2 Using a cylindrical wet aerobic fermenter (capacity 150 liters), after collecting shells after disappearance of the body, 150-1 in a dryer
The same procedure as in Example 1 was carried out except that hot-air drying was carried out at 60 ° C. for 30 to 45 minutes, and after the cultured algae were separated, hot-air drying was carried out at 140 to 160 ° C. for 30 minutes and pulverized to 100 mesh by a tumbling ball mill. A molded fuel similar to that in Example 1 was obtained.

[0031]

EFFECTS OF THE INVENTION By using shells that have been conventionally disposed of in the vicinity of a thermal power plant as a desulfurizing agent, it is possible to reduce costs and prevent the generation of sulfurous acid gas. Also,
Carbon dioxide in the exhaust gas that causes global warming is fixed and removed by photosynthesis to purify it, and at the same time, algae are cultured, and the obtained cultured algae can be used as a carbon source of briquette fuel, as a combustion improver, and as a binder. It can contribute to prevention of fuel consumption and reduction of fuel production cost. Therefore, from materials that can be easily procured at the same site, the thermal power plant and its surroundings,
A self-contained process can provide a high-value molded fuel, and at the same time can prevent pollution and environmental damage.

[Brief description of drawings]

FIG. 1 shows an example of a flowchart of a process for producing a molded body fuel.

[Explanation of symbols]

1 Shell Wash Tank 2 Wet Aerobic Fermenter 4 Washing / Draining Conveyor 5 Crusher 6 Photosynthetic Bioreactor 7 Optical Fiber Irradiation Plate 9 Separation Device 11 High Pressure Briquette Device M Motor

Claims (3)

[Claims] 1. A molded fuel containing coal powder, shell powder as a desulfurizing agent, and algae. 2. Coal powder and shell powder obtained by aerobically fermenting shellfish collected from around the thermal power plant to decompose and remove organic matter, and CO _{2 in} the exhaust gas of the thermal power plant are photosynthesized to algae. A method for producing a molded fuel, which comprises mixing and molding the cultured algae obtained by immobilization. 3. A coal crushing device, a device for aerobically fermenting recovered shellfish, a device for recovering shells from the fermentation device, a device for crushing the recovered shells, a photosynthetic bioreactor device for algae, and cultured algae. A mixing device for mixing the powder from the coal crushing device, the shell powder from the shell crushing device, and the separated cultured algae, and a mixture from the mixing device. And an apparatus for manufacturing a molded body fuel.