JP5179037B2 - Method for mixing hydrogen-generating oil mud and method for producing solid fuel - Google Patents

Description

The present invention relates to a method of mixing the hydrogen generating oil mud, in particular, low cost, yet safe way to mix the hydrogen generating oil mud, and it relates to a method for producing a solid fuel that uses the mixed method.

  Silicon wafers are useful as members for semiconductor devices, solar cells and the like, and their demand is increasing year by year. Such a silicon wafer is manufactured by cutting into a wafer form from a crystal of high-purity silicon, but in recent years, cutting with a wire saw is becoming mainstream from the viewpoint of the performance of a cutting machine.

In cutting with this wire saw, the average particle diameter is usually 10 μm as a cutting medium.
Wire saw oil containing ˜50 μm silicon carbide abrasive grains and mineral oil or aqueous solution is used. The wire saw oil cannot be used because its cutting ability is reduced due to wear of abrasive grains, an increase in silicon scraping, etc. due to repeated use.
And now, most of the waste wire saw oil that can no longer be used is incinerated and treated as industrial waste.

Moreover, in a machining factory, metal processing is performed by operating a large number of cutting, grinding, or polishing apparatuses. In the metal processing process, a large amount of cutting oil and grinding are used to cool and lubricate the workpiece. Oil and polishing oil are used. These cutting oils are also circulated and used, and the deteriorated ones are extracted, and most of them are incinerated as waste cutting oil, waste grinding oil and waste polishing oil.

Here, since oil mud such as the above-described waste wire saw oil and waste cutting oil has high energy, it is expected to be effectively used as fuel without being incinerated as industrial waste.
However, oil mud is highly viscous, has no fluidity at room temperature, or has solid content that settles and settles, so it can be handled during transportation through a pipeline. It is difficult to handle as fuel.

Therefore, in recent years, in Europe, it has been proposed that oil sludge such as crude oil sludge is not used alone, but the oil mud and sawdust are mixed to form a solid fuel and used as an alternative fuel in a cement kiln. Have been proposed (for example, Patent Document 1).
, 2, 3 etc.).

JP-A-54-39401 JP 2002-323213 A JP 2006-169376 A

However, the waste wire saw oil used for cutting silicon wafers contains a large amount of silicon particles and also contains metal particles such as iron resulting from wear of the wire saw. There is a concern that metal particles such as iron react with water and a large amount of hydrogen is generated by the following reaction formula, for example.

Si + 2OH ⁻ + H ₂ O → SiO ₃ ²⁻ + 2H ₂ ↑
Metal + Acid → Metal Compound + Hydrogen ↑
Moreover, since waste cutting oil, waste grinding oil, and waste polishing oil contain a large amount of metal particles such as aluminum particles and iron, there is a concern about the generation of hydrogen.

Oil mud such as waste wire saw oil, waste cutting oil and the like that are concerned about the generation of hydrogen as described above (in the present specification, such oil mud is referred to as “hydrogen generating oil mud”) and biomass such as sawdust, for example. When mixed, hydrogen is generated in a closed mixer, which may cause an explosion or fire.
At this time, an inert gas such as nitrogen or carbon dioxide is blown into the mixer to reduce the oxygen concentration (
8% or less) to prevent explosion or fire, etc., but in such a method, it is necessary to purchase an inert gas production facility such as nitrogen or carbon dioxide, or to purchase these inert gases Therefore, it cannot be performed at a low cost, and there is a problem of after-treatment of the exhaust gas from the mixer containing hydrogen.

The present invention has been made in view of the problems of the background art described above, and its purpose is to provide a method for mixing hydrogen-generating oil mud such as waste wire saw oil and waste cutting oil at a low cost and safely, and The object is to propose a method for producing a solid fuel using a mixing method.

In order to achieve the above-described object, the present invention, when mixing the hydrogen-generating oil mud, introduces air into the hydrogen-generating oil mud mixer, and mixes the hydrogen-generating oil mud in a state where the generated hydrogen is diluted to below the lower explosion limit concentration. In the mixing method of hydrogen generating oil mud, the hydrogen detector is provided with a hydrogen detector that constantly detects the concentration of hydrogen, and when the hydrogen detector detects hydrogen at a predetermined concentration or more, While stopping the mixing operation, the amount of air introduced into the mixer was increased, or an operation of introducing an inert gas such as carbon dioxide into the mixer was performed .
Moreover, this invention decided to manufacture a solid fuel by mixing hydrogen generating oil mud and biomass by the above-mentioned mixing method.

According to the present invention described above, a method of diluting hydrogen to a concentration that does not cause an explosion by air, that is, less than the lower explosion limit concentration, without using an inert gas such as nitrogen or carbon dioxide that needs to be manufactured or purchased. Therefore, it is possible to mix the hydrogen generating oil mud inexpensively and safely.
Moreover, according to this invention mentioned above, a solid fuel can be manufactured by mixing the hydrogen generation oil mud which was mostly discarded conventionally with biomass safely, and resources can be utilized effectively.

Hereinafter, the present invention described above is produced by mixing hydrogen-generating oil mud and biomass to produce a solid fuel,
After the solid fuel is temporarily stored, an embodiment in the case of using it as an alternative fuel in a cement kiln will be described in detail as an example.

[Hydrogen generating oil mud]
In the present invention, the hydrogen-generating oil mud refers to a liquid or sludge-like oil mud that generates hydrogen by reducing water or a hydrogen atom-containing compound. Specifically, waste wire saw oil containing silicon particles used for cutting silicon wafers, waste cutting oil containing aluminum particles and metal particles used for cooling and lubrication of workpieces in various metal machine tools, waste Grinding oil, waste polishing oil, etc. can be mentioned. These can be used alone or as a mixture of two or more of these, and also with other oil mud such as recycled heavy oil, waste solvent, crude oil sludge, diesel oil residue, etc. It may be a mixture.
Among the above, waste wire saw oil containing silicon particles has been generated in large quantities due to the recent increase in demand for silicon wafers that are useful as members for semiconductor devices, solar cells and the like. In addition, since it is an oil mud that is difficult to handle and the generation of hydrogen is concerned in both alkaline and acidic states, it is particularly preferably used as a hydrogen generating oil mud in the present invention.

〔biomass〕
Examples of biomass include crushed tatami (used waste tatami), wood chips (for example, crushed trash from construction waste), wood flour, sawdust, and paper waste.
In the present invention, biomass refers to a generic name of biological organic resources (excluding fossil fuels) that can be used as fuel.

The waste tatami used as the material of the crushed tatami mat may be any material as long as it contains at least a part of plant material. Specifically, not only the main tatami mat that uses rice straw as a tatami floor material, but also polystyrene. Foam plates (plate-shaped molded bodies formed by adding a foaming agent to a polystyrene resin composition and expanding) and insulation boards (for example, in the wet method, wood is crushed in water, and adhesives are added. Building paper tatami mats that are made of tatami flooring (soft fiberboard formed after paper making and dried), rice straw,
Also included is a sand tatami mat that uses polystyrene foam as a material for the tatami floor.
The above-mentioned wood chip refers to a crushed or crushed product of wood having a maximum particle size (mesh size with a sieve residue within 5% by mass) exceeding 5 mm and 10 mm or less.
The above-mentioned wood powder refers to a pulverized product of wood having a maximum particle size (a mesh size with a sieve residue within 5% by mass) of 5 mm or less.
The sawdust usually has a particle size distribution of about 0.5 to 5 mm. As the paper waste, for example, a shredder cut product or the like is used.

The average particle size of the biomass (aperture dimension where the balance of the sieve is within 50% by mass) is 0.5
It is preferable that it is mm or more. This is because if the average particle size is less than 0.5 mm, the entire particle system is refined, so that fluidity and dispersibility are lowered, and it becomes difficult to obtain effects such as improved handling properties.
In addition, the maximum particle size of the biomass (aperture size in which the remainder of the sieve is within 5% by mass) is 1
It is 0 mm or less, preferably 5 mm or less, more preferably 3 mm or less. When the maximum particle size exceeds 10 mm, for example, when used in a burner of a cement kiln, it is difficult to form a flame (frame), and combustion continues even after the fuel has landed. There is a risk of causing. If the maximum particle size is 5 mm or less, the proportion of particles that land and burn is reduced, and the proportion of solid fuel used can be increased, which is preferable.

[Other materials]
In addition to the above biomass, organic powder is suitably used as an absorbent for the hydrogen generating oil mud, and other materials can be blended as long as the quality is not impaired.
Examples of the organic powder include toner, heavy oil ash, pulverized coal, activated carbon powder, meat and bone powder, waste plastic powder, paper powder, and organic distillation residue powder. These organic powders may be used alone or in combination of two or more.

The toner is a dry developer used in office equipment such as a copying machine, a facsimile machine, and a printer, and is a powder having a particle size of about 7 to 11 μm. Usually, waste toner that is waste is used. Since the toner has a very small particle size and a narrow particle size distribution, it can greatly contribute to an increase in the specific gravity of the produced solid fuel and an increase in the usable amount of the hydrogen generating oil mud, which is preferably used. .
The heavy oil ash is a powder having a particle size of about 1 to 30 μm and has a small particle size, so it also contributes to an increase in the specific gravity of the produced solid fuel and an increase in the usable amount of hydrogen-generating oil mud. It can be used, so it is preferably used.
The pulverized coal is a powder having a particle size of about 10 to 100 μm and is known as a solid fuel in a firing furnace such as a cement kiln.
As said activated carbon powder and meat-and-bone powder, what has an average particle diameter of 1 mm or less is used normally. For example, waste pellets are used as the waste plastic powder. As the paper powder, for example, thunder dust or the like is used. As said organic distillation residue powder, a phthalic acid distillation residue etc. are used, for example.

The average particle size of the organic powder is ½ or less, preferably １ ／ or less of the average particle size of the biomass. When the ratio exceeds 1/2, the difference in particle size between the biomass and the organic powder becomes small, and it becomes difficult to obtain effects such as improved handling properties.
Among the above organic powders, the average particle size of the activated carbon powder composed of fixed carbon is 300.
If it exceeds μm, the number of particles that land and burn increases, and the quality of the cement clinker may deteriorate. Therefore, the average particle size is preferably 300 μm or less, more preferably 100 μm or less. The lower limit of the particle size of the organic powder is not particularly limited, but is usually 1 μm or more.

[Combination ratio]
The blending ratio of each of the above materials is as follows. First, for the biomass and the organic powder that are absorbents, the mass ratio of the biomass and the organic powder is 40/60 to 95/5, preferably 50/50 to 80 /
20. This is because when the mass ratio is less than 40/60, the blending amount of biomass is small, so that the organic powder fills the gaps between the granules of the biomass, and the fluidity of the fuel may be significantly reduced. On the other hand, when the mass ratio exceeds 95/5, the blending amount of the organic powder is small, and thus an effect such as an increase in the specific gravity of the fuel cannot be obtained sufficiently.

The blending amount of the hydrogen generating oil mud is 30 to 300 parts by mass, preferably 50 to 200 parts by mass, more preferably 80 to 150 parts by mass, particularly preferably 100 parts by mass of the total amount of the biomass and the organic powder. 100 to 140 parts by mass. If the blending amount is less than 30 parts by mass, this does not meet the purpose of effectively using the hydrogen-generating oil mud. The blending amount is 300
When the amount exceeds mass parts, oil may remain on the particle surface of the produced solid fuel, resulting in gloss and adhesion on the particle surface, and handling properties may be deteriorated.

〔mixture〕
Mixing is performed by introducing each of the above materials into the mixer at the above mixing ratio, introducing the method according to the present invention, that is, introducing air into the mixer and diluting the hydrogen generated from the mixture to a concentration that does not cause an explosion. Is called.
When the hydrogen generating oil mud and biomass are mixed, hydrogen is generated from the hydrogen generating oil mud.
There is a danger that sparks generated in the rotating part of the mixer or the like may ignite the hydrogen and cause an explosion. That is, since the lower explosion limit concentration of hydrogen is 4%, there is a risk of causing the explosion if more hydrogen is present in the mixer.
Therefore, in the present invention, air is introduced into the mixer, and the generated hydrogen concentration is diluted to a concentration that does not cause an explosion, that is, less than 4%, which is the lower explosion limit concentration. The specific amount of air introduced into the mixer is appropriately determined depending on the amount of generated hydrogen, further the volume of the mixer, the amount of the mixture, etc., but the diluent gas used in the present invention is free air. Therefore, a necessary and sufficient amount of air may be introduced into the mixer.

Moreover, it is preferable to use a mixer that is not simply provided with stirring blades but also has a structure that rotates the mixing container itself. This is because a highly viscous material such as hydrogen-generating oil mud and a material with low bulk density such as biomass can be mixed well, and the hydrogen generated by the rotation of the container flows and flows into a part of the container. This is because it does not accumulate and can be easily and reliably diluted by the introduced air.
Examples of the mixer having such a structure that also rotates the container itself include an intensive mixer manufactured by Eirich.

In addition, the mixer is equipped with a hydrogen detector that constantly detects the concentration of hydrogen, and if a hydrogen concentration higher than a predetermined level is detected, the mixing operation is immediately stopped and the amount of air introduced into the mixer In order to prevent accidents such as explosions reliably by further providing a configuration for increasing the flow rate or in some cases introducing a inert gas such as carbon dioxide into the mixer, this configuration is employed in the present invention. .

[Storage method of manufactured solid fuel]
By the mixing operation of the hydrogen generating oil mud and the biomass, the hydrogen generating oil mud is absorbed by the biomass, and a solid fuel having good handling properties can be produced.
In storing the solid fuel, air is introduced into a tank for storing the solid fuel, and hydrogen generated from the solid fuel is diluted to a concentration that does not cause an explosion.
Since the solid fuel is a mixture of hydrogen-generating oil mud and biomass, hydrogen is generated from the mixture, and there is a risk of some sparks igniting the hydrogen and causing an explosion.
Therefore , it is preferable to introduce air into the storage tank and dilute the generated hydrogen concentration to a concentration at which explosion does not occur, that is, lower than 4% which is the lower explosion limit concentration. The specific amount of air introduced into the storage tank is appropriately determined depending on the amount of hydrogen generated, the volume of the storage tank, etc., as in the case of the above mixing, but a necessary and sufficient amount of air is supplied to the storage tank. It should just be introduced in.

The storage of the solid fuel includes not only the case of long-term storage but also the case where the manufactured solid fuel is temporarily stored in the tank to be measured because the manufactured solid fuel is used immediately.
As in the case of the above mixer, a hydrogen detector that constantly detects the concentration of hydrogen is provided in the storage tank. If hydrogen at a predetermined concentration or higher is detected, air is introduced into the storage tank. It is preferable to further provide a configuration for increasing the amount or, in some cases, a configuration for introducing an inert gas such as carbon dioxide into the storage tank in order to reliably prevent an accident such as an explosion.

[How to use solid fuel]
An example of a method of using the solid fuel thus manufactured and stored is a method of using the solid fuel that is introduced into a firing furnace via a pipe and burned as fuel.
At this time, at the time of production and / or storage of the solid fuel, specifically, air used for diluting hydrogen when mixing the hydrogen-generating oil mud and biomass, or used for diluting hydrogen when storing the solid fuel. It is preferable that air is supplied into the firing furnace as combustion air. Thereby, it becomes possible to process a lot of exhaust gas containing hydrogen from a mixer or a storage tank safely and effectively.
Here, examples of the firing furnace include a cement kiln for producing a clinker and a kiln for firing quick lime and lightweight aggregate.

Next, referring to the drawings, an embodiment of a method for mixing hydrogen-generating oil mud according to the present invention, a method for producing solid fuel using the mixing method, and a method for storing the solid fuel will be described.
FIG. 1 is a diagram conceptually illustrating a solid fuel production facility and a cement kiln using the solid fuel.

As shown in the figure, first, one batch of waste tatami mat A weighed by a predetermined method is put into the crusher 1, and the proportion of crushed material having a length of 5 cm or less is reduced to 80% by mass or more. It is crushed. And the crushed material of the obtained waste tatami A is conveyed by the conveyor 2, and organic powder (toner, heavy oil ash) is quantitatively supplied from the storage device 3 in the middle thereof, and is mixed into the hopper 4 in a state where both are mixed. Stored.

One batch of crushed waste A (about 200 kg) stored in the hopper 4 is mixed with a mixer (about 200 kg).
A batch of hydrogen-generated oil mud (waste wire saw oil about 200 kg) X is charged into an Eirich mixer (Eirich mixer) 5 and stirred and mixed for a predetermined time (about 4 minutes). On this occasion,
A predetermined amount (up to about 20 m ³ / min) of air is introduced into the mixer 5, and the mixing operation is performed while diluting the hydrogen generated from the mixture to a concentration that does not cause an explosion. Further, the hydrogen detector 6 is installed in the mixer 5, and in the unlikely event that hydrogen of a predetermined concentration or more is detected,
An operation control panel 7 is provided for performing control such as immediately stopping the mixing operation and introducing CO ₂ gas into the mixer 5.

Through the above mixing operation, the hydrogen-generating oil mud X is absorbed by the solid material such as the crushed material of the mixed waste tatami A and becomes the solid fuel Y. The solid fuel Y discharged from the mixer 5 is crushed by a crusher 8 installed downstream thereof, conveyed upward by a conveyor 9, foreign matters are removed by a drum magnetic separator 10, and its particle size is obtained by a trommel 11. Is prepared and stored in the storage tank 12.

A predetermined amount (up to about 30 m ³ / min) of air is introduced into the storage tank 12, and storage is performed while diluting hydrogen generated from the solid fuel Y to a concentration that does not cause an explosion.
Similarly to the case of the mixer 5 described above, the hydrogen detector 6 is installed in the storage tank 12, and in the unlikely event that hydrogen of a predetermined concentration or more is detected, CO ₂ gas is stored in the storage tank 12. It is connected to the operation control panel 7 for performing control such as introduction to the above. The solid fuel Y stored in such a state is measured by the meter 13 and is pneumatically fed toward the burner 15 instead of or in combination with the pulverized coal that is the main fuel of the cement kiln 14. The fuel is injected into the cement kiln 14 from the fuel injection port of the burner 15.

The solid fuel Y introduced into the cement kiln 14 is completely burned in a short time before landing on the furnace bottom by the flame from the burner 15, and the combustion residue of the solid fuel Y becomes a part of the components of the clinker. . Further, the air used for diluting the hydrogen exhausted from the mixer 5 and the storage tank 1
Both of the air used for diluting the hydrogen exhausted from 2 are guided to the clinker cooler 17 through the bag filter 16 and used for cooling the clinker and also used as combustion air in the cement kiln 14.

On the other hand, the foreign matter or the like in the solid fuel Y removed by the drum magnetic separator 10 and the trommel 11 is introduced from the kiln bottom of the cement kiln 14 and used as fuel, and the residue becomes a part of the clinker component. .

As mentioned above, although the example of the mixing method of the hydrogen generation oil mud concerning the present invention, the manufacturing method of the solid fuel using the mixing method, and the storage method of the solid fuel have been described, the present invention is not limited to the implementation described above. The present invention is not limited to the examples, and various modifications and changes are naturally possible within the scope of the technical idea of the present invention described in the claims.

It is the figure which showed notionally the manufacturing facility of the solid fuel which implement | achieves this invention, and the cement kiln which uses the solid fuel.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Crusher 2 Conveyor 3 Organic powder storage device 4 Hopper 5 Mixer 6 Hydrogen detector 7 Operation control panel 8 Crusher 9 Conveyor 10 Drum magnetic separator 11 Trommel 12 Storage tank 13 Meter 14 Cement kiln 15 Burner 16 Bag filter 17 Clinker cooler A Waste tatami X Hydrogen generating oil mud Y Solid fuel

Claims (5)

Upon mixing of the hydrogen generating oil mud, introducing air into the mixer of the hydrogen generating oil mud, the method of mixing the hydrogen generating oil mud for mixing the hydrogen generation oil mud while diluting hydrogen generated to below the lower explosive limit concentration, the mixture A hydrogen detector that constantly detects the concentration of hydrogen is provided in the machine, and when the hydrogen detector detects a hydrogen concentration higher than a predetermined level, the mixing operation of the hydrogen-generating oil mud is stopped, and A method for mixing hydrogen-generating oil mud, characterized by performing an operation of increasing an air introduction amount or introducing an inert gas such as carbon dioxide into the mixer.   The method for mixing hydrogen-generating oil mud according to claim 1, wherein the hydrogen-generating oil mud is liquid or sludge-like oil mud that generates hydrogen by reduction of water or a hydrogen atom-containing compound.   The hydrogen generating oil mud is at least one of waste wire saw oil, waste cutting oil, waste grinding oil, and waste polishing oil containing silicon particles and / or aluminum particles and metal particles. 2. The method for mixing hydrogen-generating oil mud according to 1.   A method for producing a solid fuel, wherein the hydrogen-generating oil mud and biomass are mixed by the mixing method according to any one of claims 1 to 3.   The method for producing a solid fuel according to claim 4, wherein the biomass is at least one of waste crushed material, wood chips, wood flour, sawdust, and paper waste.

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