JPH0662969B2 - Stable solid fuel / water slurry - Google Patents

Description

TECHNICAL FIELD The present invention relates to a stable solid fuel / water slurry, and more specifically, it has a high concentration and low viscosity, and is easy to transport, store, and handle. The present invention relates to a solid fuel / water slurry having excellent stability without solid fuel particles settling or consolidating during long-term storage and transportation.

[Prior Art and Problems Thereof] In recent years, solid fuels such as coal and petroleum coke have been reviewed as energy sources. However, the solid fuel has a drawback that it is difficult to smoothly transport and store it, and the working efficiency is poor in handling, as compared with a liquid fuel such as petroleum.

In order to improve these drawbacks, development of a solid fuel / water slurry in which a solid fuel is made into a fine powder and dispersed in water is under way. However, in the solid fuel / water slurry,
When the concentration of the solid fuel is increased, the viscosity of the solid fuel / water slurry becomes extremely high, the fluidity is lost, and it becomes difficult to handle and transport it by pipe. In addition, if the concentration of the solid fuel is reduced in order to reduce the viscosity of the solid fuel / water slurry, the transportation efficiency will be reduced, and dehydration treatment will be required before it can be used as a fuel or a gasification raw material. There are difficulties.

In order to solve these difficulties, various attempts have been made to add a dispersant to the solid fuel / water slurry and adjust the particle size distribution of the solid fuel particles.

However, by such a method, even if the viscosity of the solid fuel / water slurry containing the solid fuel at a high concentration is reduced, the solid fuel / water slurry can be stored for a long period of time,
When transported by a tank truck or a tanker, solid fuel particles often settle, and a solid solid settling layer is often formed by a dehydration phenomenon due to consolidation of the sediment. Since it is extremely difficult to re-disperse such a solid sedimentation layer into a solid fuel / water slurry for use, it is important to improve the stability of the high concentration and low viscosity solid fuel / water slurry. -It is extremely important for practical use of water slurry.

Conventionally, addition of various stabilizers has been proposed in order to improve the stability of solid fuels and water slurries, but none of them is still satisfactory.

[Object of the Invention] The present invention has a low viscosity while containing solid fuel particles in a high concentration, and has a stability that does not cause sedimentation or consolidation of solid fuel during long-term storage and transportation. The object is to provide an extremely excellent solid fuel / water slurry.

[Structure of the Invention] The present invention relates to a solid fuel / water slurry 10 containing 50 to 80 parts by weight of solid fuel particles composed of coal and / or petroleum coke.
0 parts by weight, natural gum, a modified product of natural gum, polyvinyl alcohol, polyacrylamide, 1 to 20% by weight of at least one water-soluble polymer substance selected from carboxymethyl cellulose and hydroxyethyl cellulose,
Bentonite, attapulgite, sepiolite and chrysotile asbestos characterized by containing at least 0.01 to 0.5 parts by weight of a stabilizer, which is a mixture of 80 to 99% by weight of at least one particulate inorganic substance selected from the group consisting of asbestos Stable solid fuel / water slurry.

The solid fuel in the present invention is coal and / or petroleum coke. The coal and petroleum coke are not particularly limited, and those generally used as fuel can be used. Particularly preferred coal is one having an ash content of about 6% or less. It is also possible to preferably use deashed coal, for example, coal having an ash content of about 10% and deashed by a method known per se such as a heavy liquid coal preparation method and having an ash content of about 6% by weight or less. As the petroleum coke, petroleum coke generally produced as a by-product from the petroleum refining process is used, and usually contains 0.1 to 1% by weight of ash.

The content of the solid fuel in the solid fuel / water slurry of the present invention is 50 to 80% by weight, preferably 65 to 75% by weight. As the solid fuel, the geometric mean diameter of the particles is 74 μm or less, particularly 20 to 53 μm, and the particle size distribution of the particles is such that the value of the geometric standard deviation δg in the lognormal distribution is within the range of 6 to 12. Solid fuels are preferred.

The terms "geometric mean diameter" and "geometric standard deviation" are as follows:
It is a term generally used to define the particle size of powder and its distribution, and is defined as follows from the relationship between the particle size in a lognormal distribution and the cumulative passing weight percentage.

Geometric mean diameter (Dp50): Particle size geometric standard deviation (δg) corresponding to cumulative passing weight percentage of 50%: Ratio of geometric mean diameter to particle size corresponding to cumulative passing weight percentage of 15.87% (geometric mean diameter / The ratio of the particle size equivalent to the cumulative passing weight of 15.87%) δg ₁ and the particle size corresponding to a cumulative passing weight percentage of 84.13% to the geometric mean diameter (cumulative passing weight 84.13
% (Particle size / geometric mean diameter corresponding to%) arithmetic average of δg ₂ [(δg ₁ + δg ₂ ) / 2] The stabilizer used in the present invention is guar gum, xanthan gum, locust bean gum, karaya gum, sodium alginate and the like. Natural gums; modified products such as acetylated or alkylated products of these natural gums; at least one selected from water-soluble synthetic polymers such as polyvinyl alcohol and polyacrylamide, and water-soluble cellulose derivatives such as carboxymethyl cellulose and hydroxyethyl cellulose 1 to 20% by weight, preferably 2 to 10% by weight, and at least one inorganic substance 80 to 99 selected from the group consisting of bentonite, attapulgite, sepiolite and chrysotile asbestos.
%, Preferably 90-98% by weight. If the proportion of the inorganic substance is smaller than the above range, the stability at low viscosity tends to be poor.

The amount of the stabilizer added is in the range of 0.01 to 0.5 parts by weight, preferably 0.02 to 0.2 parts by weight, based on 100 parts by weight of the solid fuel / water slurry. If the amount of the stabilizer added is less than the above range, the stability of the fixed fuel / water slurry will be insufficient, and if it is more than the above range, the viscosity of the solid fuel / water slurry will increase and the fluidity will decrease. However, the content of solid fuel must be reduced to maintain fluidity.

As a method for producing the solid fuel / water slurry of the present invention, for example, a dry or wet pulverizer which is usually used for solid fuel is used to produce solid fuel particles having various desired geometric mean diameters. There is a method in which these are prepared and mixed so that the particle size distribution of the solid fuel particles of the mixture becomes a desired value, and a stabilizer and water are added to this and the mixture is vigorously stirred. It is not preferable to add the stabilizer before pulverizing the solid fuel because the stabilizing effect cannot be sufficiently exhibited.

The solid fuel / water slurry of the present invention may contain an additive such as a suitable dispersant in order to suppress the increase in viscosity due to the increase in concentration. As the dispersant, a substance known per se can be used, and examples thereof include naphthalene sulfonate, petroleum sulfonate, lignin sulfonate, and formalin condensates thereof; polyoxyethylene alkyl ether sulfate ester salt, Examples thereof include polyoxyethylene alkylaryl ether sulfate ester salt; sulfated product of polyglycerin; sulfonate salt of melamine resin; sulfonate salt of coal extract.

The dispersant is 100 parts by weight of the solid fuel / water slurry,
It is suitable to use in an amount in the range of 0.01 to 3 parts by weight.
Further, the dispersant can be added at any point in the manufacturing process of the solid fuel / water slurry, for example, at the time of crushing the solid fuel, at the time of mixing the solid fuel and water, or after manufacturing the solid fuel / water slurry. .

An alkaline substance such as sodium hydroxide, potassium hydroxide or ammonium hydroxide may be added to the solid fuel or water slurry of the present invention as a pH adjuster.

EFFECTS OF THE INVENTION The fixed fuel / water slurry of the present invention has a low viscosity while containing a solid fuel at a high concentration, and therefore can be industrially used similarly to a liquid fuel. Further, since the fixed fuel / water slurry of the present invention has excellent stability, it retains sufficient fluidity even after long-term storage and can be transported over a long distance.

Therefore, the solid fuel / water slurry of the present invention is
It can be suitably used as a fuel in a heating furnace or the like, or as a raw material for gasification in the production of hydrogen, carbon monoxide and the like.

Next, examples and comparative examples will be shown. Properties of solid fuel, preparation of solid fuel particles, solid fuel in Examples and Comparative Examples
The method for producing the water slurry and the method for measuring the viscosity of the solid fuel / water slurry, the storage stability test method, and the transport stability test method are shown below.

(1) Properties of solid fuel Demineralized coal having the following properties was used.

Industrial analysis (wt%): Water content 5.3 (constant temperature bath) Ash 0.7 [JISM8812] Volatile content 38.8 Fixed carbon 55.2 (2) Preparation of solid fuel particles Coarse granular solids crushed to a geometric mean diameter of about 90 μm with a Nara free crusher Fuel and finely divided solid fuel obtained by wet-milling the coarse-grained solid fuel with a ball mill to a geometric mean diameter of about 9 μm were mixed and mixed in a weight ratio of 60:40 on an absolute dry basis, and mixed to obtain a finely divided solid. Fuel particles were prepared.

(3) Manufacture of solid fuel / water slurry Solid fuel set to a predetermined concentration and water in which a dispersant and a pH adjuster were dispersed were placed in a mixing container at room temperature and premixed by hand stirring. After that, using a lab disper manufactured by Tokushu Kika Kogyo Co., Ltd., the mixture was stirred for 3 minutes at a rotation speed of about 3000 rpm to produce a primary solid fuel / water slurry, and a stabilizer was added in a predetermined amount to the slurry. After premixing by stirring, the above-mentioned lab disper was again stirred for 3 minutes at a rotation speed of about 3000 rpm to produce a solid fuel / water slurry.

(4) Method for measuring viscosity of solid fuel / water slurry The viscosity of the solid fuel / water slurry was measured using a B-type rotational viscometer manufactured by Tokyo Keiki (using a No. 3 rotor). The measurement is
The measurement was performed at a temperature of 27 ° C. and a rotation speed of 12 rpm, and the value 1 minute after the start of measurement was read.

(5) Storage stability test method of solid fuel / water slurry Charge the solid fuel / water slurry into a 100 ml glass sample tube container and let it stand still. After 7 days, penetrate the glass rod and settle near the bottom of the container. The stability of solid fuel and water slurry was evaluated by the method of examining the presence or absence of a substance and the degree of consolidation. The case where a solid sedimentation layer was observed was defined as "poor", the case where a solid sedimentation was observed was defined as "slightly poor", and the case where no solid sedimentation was observed was defined as "good".

(6) Transport stability test method for solid fuel / water slurry The solid fuel / water slurry was charged into a 100 ml glass sample tube container and subjected to horizontal vibration of an amplitude of 40 mm and a frequency of 90 min ^{- 1} for 5 times.
After giving the time, the stability of the solid fuel / water slurry was evaluated by a method of penetrating a glass rod and examining the presence or absence of sediment near the bottom of the container and the degree of consolidation. The case where a solid sedimentation layer was required was defined as "poor", the case where a solid sediment was recognized was defined as "slightly poor", and the case where a solid sediment was not recognized was defined as "good".

[Examples 1 to 3] The deashed coal was used as a solid fuel, and 0.5% by weight of a solid fuel / water slurry was used as a dispersant formalin condensate of sodium β-naphthalenesulfonate.
As described above using ammonium hydroxide as the H modifier, solid fuel concentration 70% by weight, viscosity 800 mPa s, pH 8.
0 primary solid fuel / water slurry was prepared, and then the stabilizer shown in Table 1 was added in the amount shown in Table 1 to prepare a solid fuel / water slurry having a viscosity of about 1000 mPa s as described above. The results of the storage stability test and the transportation stability test are shown in Table 1.

[Comparative Examples 1 to 6] As the stabilizer, a single component as shown in Table 1 was used (Comparative Examples 1 to 5), or a mixture having a composition outside the scope of the present invention was used (Comparative Example). 6) A solid fuel / water slurry having a viscosity adjusted to about 1000 mPa s was produced in the same manner as in Example except for the above. The results of the storage stability test and the transportation stability test are shown in Table 1.

[Evaluation Results] From the comparison between the examples and the comparative examples, the solid fuel / water slurry of the present invention containing a stabilizer in which a specific organic substance and a specific inorganic substance are combined in a specific ratio shows excellent stability. It is clear to show.

Claims (6)

[Claims] 1. A solid fuel / water slurry containing 50 to 80 parts by weight of solid fuel particles composed of coal and / or petroleum coke.
100 parts by weight of 1 to 20% by weight of at least one water-soluble polymer selected from natural gum, modified natural gum, polyvinyl alcohol, polyacrylamide, carboxymethyl cellulose and hydroxyethyl cellulose
And 0.01-0.5 parts by weight of a stabilizer, which is a mixture of bentonite, attapulgite, sepiolite and at least one type of particulate inorganic substance 80-99% by weight selected from the group consisting of chrysotile-based asbestos. Solid fuel / water slurry characterized by. 2. The natural gum selected from guar gum, xanthan gum, locust bean gum, karaya gum and sodium alginate or a modified product thereof, wherein the water-soluble polymer substance is a natural gum or a modified product thereof. Solid fuel / water slurry. 3. The stabilizer according to claim 1, wherein the stabilizer comprises 2 to 10% by weight of the water-soluble polymer substance and 90 to 98% by weight of the particulate inorganic substance. The solid fuel / water slurry according to the item. 4. The solid fuel / water slurry according to claim 1, wherein the stabilizer is contained in an amount of 0.02 to 0.3 part by weight per 100 parts by weight of the solid fuel / water slurry. 5. The solid fuel / water slurry according to claim 1, wherein the content of the solid fuel in the fixed fuel / water slurry is in the range of 65 to 75% by weight. 6. The solid average particle diameter of the solid fuel particles is 74 μm or less, and the particle size distribution of the solid fuel particles is adjusted so that the value of the geometric standard deviation δg in the lognormal distribution is in the range of 6 to 12. The solid fuel / water slurry according to claim 1, wherein