JPH0224879B2 - - Google Patents

Description

[Detailed description of the invention]

The present invention relates to a method for producing a solid fuel-water slurry with low viscosity and high concentration. More particularly, the present invention relates to improvements in methods for producing solid fuel-water slurries by mixing solid fuels, such as coal, petroleum coke, etc., with water or water and dispersants, such as transportation, storage, handling, etc. The present invention relates to a method for producing a low-viscosity, high-concentration solid fuel-water slurry that is easy to produce. In recent years, solid fuels such as coal and petroleum coke have been reconsidered as energy sources. However, coal, petroleum coke, etc. are not only difficult to transport and store smoothly compared to fluid fuels such as petroleum, but also the costs involved are high.
It has the disadvantage that it is less efficient in handling and is more difficult to use than petroleum. Therefore, in order to improve these drawbacks, progress is being made in developing methods to make solid fuel into a fine powder, such as coal, and disperse it in water to make a solid fuel-water slurry, such as a coal-water slurry. There is. However, when coal is turned into a coal-water slurry, increasing the concentration of coal generally increases the viscosity of the slurry significantly, resulting in loss of fluidity and difficulty in handling and pipe transportation. On the other hand, if the concentration of coal is lowered in order to lower the viscosity of the slurry, there are disadvantages in that the transportation efficiency decreases and a dehydration step is required as a post-treatment for use as fuel or gasification raw material. In order to solve these problems, it is necessary to produce a solid fuel-water slurry with low viscosity and high concentration, such as coal-water slurry.
Regarding the manufacturing method of water slurry, for example, there is a method in which pulverized solid fuel is mixed with water and a dispersant to reduce the slurry viscosity, and a method in which pulverized solid fuel with adjusted particle size distribution is used as the solid fuel. A method of increasing the concentration of solid fuel in slurry by mixing it with water or water and a dispersant is known.
Methods and methods are effective to a certain extent in reducing the viscosity and increasing the concentration of the slurry, but none of the methods can be said to be sufficient and there is room for improvement. The present inventors further conducted extensive research with the aim of developing a method for industrially advantageously producing a solid fuel-water slurry with a low viscosity and high concentration. As a result, solid fuels with low ash content, such as petroleum coke or deashed coal, and solid fuels with high ash content, such as undeashed coal, are used as solid fuels. A small amount of solid fuel is wet-pulverized with water or water and a dispersant to produce a slurry with a constant concentration in which the geometric mean diameter of the solid fuel is adjusted to a small value, and then a solid fuel with a high ash content is wet-pulverized along with this slurry. The inventors learned that the above objective could be achieved by adjusting the particle size distribution of the solid fuel in the slurry within a certain wide range, and after further research, they arrived at the present invention. The present invention provides a method for producing a solid fuel-water slurry by wet-pulverizing a solid fuel with water or water and a dispersant, in which a solid fuel (A) with a low ash content is used.
is wet-pulverized with water or water and a dispersant so that the solid fuel (A) concentration is 30 to 60% by weight to produce a slurry in which the geometric mean diameter of the solid fuel (A) is adjusted to about 44μ or less. The solid fuel (B), which has a higher ash content than the solid fuel (A), is wet-pulverized together with the slurry produced in the first step. The solid fuel in the fuel-water slurry has a geometric mean diameter of 150μ or less and a particle size distribution with the geometric standard deviation σg of a lognormal distribution.
The present invention relates to a method for producing a solid fuel-water slurry, which is characterized in that the slurry is adjusted to have a particle diameter in the range of 6.0 to 12. "Geometric mean diameter" as used herein
The terms "geometric standard deviation (σg)" and "geometric standard deviation (σg)" are commonly used terms to define the particle size of powder and its distribution, and each term refers to the particle size and cumulative passing weight in a lognormal distribution. It is defined as follows from the relationship of %. Definition of geometric mean diameter: Particle diameter corresponding to 50% cumulative passing weight % Definition of geometric standard deviation (σg): Ratio of geometric mean diameter to particle diameter corresponding to 15.87% cumulative passing weight % (geometric mean diameter /Particle size corresponding to 15.87% of cumulative passing weight) σg ₁ and cumulative passing weight%
The ratio of the particle size corresponding to 84.13% to the geometric mean diameter (particle size corresponding to cumulative passing weight% 84.13%/geometric mean diameter) arithmetic mean with σg ₂ (σg ₁ +σg ₂ /2) According to the present invention, It has the great advantage of being able to easily produce a low viscosity solid fuel-water slurry with high solid fuel concentration and practical fluidity. Therefore, the solid fuel-water slurry produced by the present invention is easy to transport through pipes, inject with burners, and handle, and can be used as a fuel in boilers, power plants, heating furnaces, etc. It is suitable for use as a gasification feedstock, such as in the production of carbon oxide, etc. In addition, in the present invention, the solid fuel-water slurry can not only be prepared industrially by a simple operation, but also use a solid fuel with a low ash content that has been completely deashed. Since it is not necessary, it is possible to greatly reduce the cost required for deashing. In addition, in the present invention, a solid fuel-water slurry with low viscosity and high concentration can be obtained, so that it can be used for various purposes without any special dehydration treatment at the time of use. Furthermore, in the present invention,
First, a solid fuel with a low ash content is wet-pulverized to produce a slurry, and then a solid fuel with a high ash content is wet-pulverized together with this slurry to produce a solid fuel-water slurry.The solid fuel is pulverized and mixed. Stirring operations can be performed at the same time, making it easy to adjust the particle size of solid fuel and grinding operations, etc., as well as efficiently producing low-viscosity, high-concentration solid fuel-water slurry without scattering dust into the surrounding area. It is possible to do so. Next, the present invention will be explained in more detail. [First step] In the first step, the solid fuel (A) with a low ash content is converted into a solid fuel (A) with a concentration of 30 to 60%.
% by weight, preferably 40-55% by weight.
The solid fuel (A) is wet-milled with water or water and a dispersant so that the geometric mean diameter of the solid fuel (A) is about 44μ or less, preferably
Produces slurry adjusted to 20μ or less. If the concentration of the solid fuel (A) is too low, the pulverization efficiency will be poor, and if it is too high, it will be difficult to adjust the geometric mean diameter and the pulverization operation, etc. Therefore, the concentration of the solid fuel (A) should be within the above range. As such, wet milling with water or water and a dispersant is required. The size of the solid fuel (A) before wet pulverization is not particularly limited, but it is generally appropriate to coarsely pulverize the solid fuel to a geometric mean diameter of about 3 mm or less. If a solid fuel with a high ash content, such as undeashed coal (usually around 10% by weight of ash content), is used instead of the solid fuel (A) with a low ash content, the resultant product obtained in the second step described below It is necessary to use a solid fuel (A) with a low ash content in the first step because it will prevent the solid fuel-water slurry from becoming low in viscosity and high in concentration, making it difficult to achieve the object of the present invention. As a solid fuel (A) with a low ash content, petroleum coke, which is a by-product from the oil refining process (usually has an ash content of about 0.1~
1% by weight) or deashed coal, for example, commercially available coal containing an ash content of around 10% by weight, which is deashed by a method known per se such as heavy liquid coal washing, and has an ash content of approximately 6% by weight. Below, preferably 5
Examples include those of less than % by weight.
As mentioned above, the reason why low viscosity and high concentration are inhibited when solid fuel with high ash content, such as undeashed coal, is used is not fully clear, but if the geometric mean diameter is larger than approximately 44 μ This is thought to be due to the fact that as the coal becomes smaller, the surface area increases significantly, making it easier for the ash in undeashed coal to be released into the water, increasing the amount of inorganic minerals leached into the water. If the geometric mean diameter of the wet-pulverized solid fuel (A) in the first step is too large, the particle size distribution of the solid fuel in the slurry will become narrow when the solid fuel (B) is wet-pulverized in the second step described below. In the first step, it is necessary to adjust the geometric mean diameter of the solid fuel (A) to about 44μ or less, preferably 20μ or less, since this becomes a factor that inhibits the solid fuel-water slurry from becoming highly concentrated. In wet-pulverizing the solid fuel (A) together with water or water and a dispersant, a conventionally known wet-pulverizer such as a ball mill, tube mill, vibration mill, etc. is appropriately used. Further, as the dispersant, any conventionally known dispersant for solid fuel-water slurries can be used. Examples of dispersants include naphthalene sulfonates, petroleum sulfonates, lignin sulfonates, and formalin condensates thereof; polyoxyethylene alkyl ether sulfate salts, polyoxyethylene alkylaryl ether sulfate salts; polyglycerin Sulfonates of melamine resins; sulfonates of coal extracts (see Japanese Patent Application No. 1987-19295), and the like. The above-mentioned sulfonate of coal extract is obtained by extracting coal at a temperature of 200 to 500°C using a solvent having a critical temperature lower than the extraction temperature and under a pressure higher than the critical pressure. Preference is given to those obtained by sulfonating a coal extract obtained by sulfonation and then neutralizing it using an alkalizing agent. Solvents used in this extraction include benzene, toluene, O-xylene, m
- Aromatic hydrocarbons such as xylene, p-xylene, xylene mixtures, ethylbenzene, propylbenzene, alicyclic hydrocarbons with 5 or more carbon atoms such as cyclopentane, cyclohexane, 6 or more carbon atoms such as hexane, heptane, nonane, etc. Examples include aliphatic hydrocarbons, aliphatic amines such as methylamine, ethylamine, and dimethylamine, and heterocyclic compounds such as pyridine, among which aromatic hydrocarbons are preferred. For sulfonation, for example, sulfuric acid, fuming sulfuric acid, sulfuric anhydride, chlorosulfonic acid, etc. are used, and as the alkalizing agent, hydroxides of alkali metals and alkaline earth metals are generally used. It is appropriate that the amount of the dispersant used is 0.01 to 3% by weight based on the solid fuel-water slurry obtained in the second step described below. In addition to the dispersant, an alkali metal base, such as sodium hydroxide, a polysaccharide, such as starch, a natural gum, or a thickener, such as CMG (carboxymethyl cellulose sodium salt), may be mixed, and the amount used will be described later. It is desirable that the amount is 2% by weight or less based on the solid fuel-water slurry obtained in the two steps. In addition, when mixed with water and a dispersant, the pulverization efficiency in the first and second steps is improved compared to when mixed with water alone, and the target solid fuel with low viscosity and high concentration is stable. A slurry is obtained. The slurry obtained in the first step by wet-pulverizing the solid fuel (A) with a low ash content together with water or water and a dispersant to adjust the concentration and geometric mean diameter is led to the next second step. [Second Step] In the present invention, in the second step, a solid fuel having a higher ash content than the solid fuel (A) used in the first step is used.
(B) is wet-pulverized together with the slurry obtained in the first step, and the geometric mean diameter of the solid fuel (mixture of solid fuel (A) and (B)) in the solid fuel-water slurry obtained is
Adjustment is made so that the particle size distribution is 150μ or less, preferably 74μ or less, and the geometric standard deviation σg in a lognormal distribution is in the range of 6.0 to 12. When the geometric mean diameter and particle size distribution of the solid fuel are adjusted to the above range by wet pulverization, the desired solid fuel-water slurry with low viscosity and high concentration can be obtained. As the solid fuel (B), one having a higher ash content than the solid fuel (A) is used, such as undeashed coal (usually ash content 10% by weight). Therefore, there is an advantage that the cost required for deashing treatment is reduced. In addition, in the second step, the geometric mean diameter and particle size distribution of the solid fuel (mixture of solid fuels (A) and (B)) in the obtained solid fuel-water slurry may be adjusted as described above. Then, the solid fuel (B) does not need to be pulverized so much and only needs to be relatively coarse particles, so the cost required for pulverization can be reduced, and it is possible to reduce the amount of inorganic minerals in the slurry, which are considered to be a factor that inhibits high concentration. This has the effect of preventing elution and reducing the influence of inorganic minerals regardless of the type of solid fuel (B) used (for example, type of coal). The size of the solid fuel (B) used during wet pulverization together with the slurry obtained in the first step is not particularly limited, but generally the geometric mean diameter is larger than about 44μ.
A thickness of about 3 mm or less is suitable. The present inventors wet-pulverized the solid fuel (B) together with the slurry obtained in the first step, and determined that the geometric standard deviation σg
It was discovered that the larger the value of (the broader the particle size distribution), the better the fluidity of the slurry even at high concentrations, and the easier the pulverization operation in the second step. In order to increase the value of σg, solid fuel B
It is necessary to increase the geometric mean diameter by reducing the degree of wet pulverization of solid fuel A, or to make the geometric mean diameter of solid fuel A as small as possible in the first step, but if the geometric mean diameter in the resulting slurry is too large. If it becomes too large, the reactivity and combustibility of the slurry will deteriorate, and even if the geometric mean diameter of solid fuel A is to be reduced, there is an industrial limit to the degree of pulverization, and it is not economical to pulverize it extremely finely. . Furthermore, if the value of σg becomes too small, the particle size distribution in the slurry will become narrower, and the viscosity of the slurry will increase when trying to increase the concentration. Therefore, considering the above points, in the second step, the geometric mean diameter of the solid fuel (mixture of solid fuels (A) and (B)) in the obtained solid fuel-water slurry is
It is necessary to adjust the particle size distribution so that it is 150μ or less, preferably 74μ or less, and the geometric standard deviation σg is in the range of 6.0 to 12. In the second step, when wet-pulverizing the solid fuel (B) together with the slurry obtained in the first step,
It is preferable to use a conventionally known wet mill, such as a ball mill, tube mill, attrition mill, hammer mill, or rod mill, as appropriate. The ratio of solid fuel (A) and solid fuel (B) in the slurry obtained in the second step is (A)/(B) = 0.05 to 2 by weight.
It is desirable to set it to preferably 0.1 to 1. If the proportion of the solid fuel (A) is too small, the effects of the present invention will not be sufficiently expressed, and if the proportion is too large, not only will the cost required for pulverization increase, but also the deashed coal will be used as the solid fuel (A). When using ash, the cost required for deashing increases, so it is better to wet-pulverize the solid fuel (B) together with the slurry obtained in the first step so that the above ratio is achieved. Next, one embodiment of the present invention will be described with reference to FIG. [First Step] Water or water and a dispersant are supplied from line 15 to stirring tank 1, and then supplied to wet crusher 6 via line 16, pump 2, line 17, flow meter 3, and line 18. On the other hand, solid fuel (A) is on line 1
9. Through the hopper 13, line 20, metering feeder 4, and line 21, the concentration of solid fuel (A) in the slurry is
If necessary, it is coarsely crushed in a coarse crusher 5 to a concentration of 30 to 60% by weight, and then supplied from a line 22 to a wet crusher 6. In the wet crusher 6, water or water and a dispersant are mixed with the solid fuel (A) and the solid fuel is
A slurry containing the solid fuel (A) is produced by simultaneously pulverizing the solid fuel (A) so that the geometric mean diameter of the solid fuel (A) is approximately 44 μm or less. Part of the slurry is
It may be circulated to the wet grinder 6 from the line 25 via the line 23, the pump 7, and the line 24. Circulation improves the wet pulverization efficiency of the solid fuel A, and also facilitates the mixing and pulverizing operations of the solid fuel (A) and water or water and a dispersant. [Second process] The slurry produced in the first process is transferred to line 23,
It is supplied to the wet crusher 11 from a line 27 via a pump 7, a line 24, a line 26, and a flow meter 8. On the other hand, solid fuel is on line 28, hopper 14,
After passing through line 29, quantitative feeder 9, and line 30,
If necessary, it is coarsely pulverized by a pulverizer 10 and then transferred to line 3.
1 to a wet crusher 11. In the wet crusher 11, while simultaneously mixing the slurry produced in the first step with the solid fuel (B) and crushing the solid fuel B, the solid fuel (a mixture of solid fuels (A) and (B)) is mixed.
The particle size distribution is adjusted so that the geometric mean diameter is 150μ or less and the geometric standard deviation σg of the lognormal distribution is in the range of 6.0 to 12. Through adjustment, a solid fuel-water slurry with a desired low viscosity and high concentration can be obtained. The solid fuel-water slurry adjusted by the wet crusher 11 is led to the slurry tank 12 through a line 32,
It is taken out from line 35 via line 33, pump 43, and line 34. A portion of the solid fuel-water slurry may be circulated through line 36 to wet mill 11 . Next, examples and comparative examples will be shown. In each example, the slurry viscosity was measured using a B-type viscometer (manufactured by Tokyo Keiki). Further, as the solid fuel, those having the industrial analysis values (constant humidity basis) listed in Table 1 were used.

[Table] In addition, the total water content of each solid fuel in Table 1 (JIS-M
-8811) was 1.1% by weight of petroleum coke, 4.1% by weight of deashed Wallara charcoal and 3.0% by weight of undeashed Wallara charcoal. Example 1 Water 13.4Kg/hr and dispersant (β-naphthalenesulfonic acid formalin condensate) 0.32Kg/hr were added to stirring tank 1.
hr and stabilizer (sodium hydroxide) 0.15Kg/hr
are supplied, mixed, and introduced into a wet pulverizer (agitator mill) 6 to produce solid fuel (A) having the properties listed in Table 1.
(Petroleum coke: Geometric mean diameter approx. 1mm) 14.3Kg/hr
The petroleum coke concentration is
51.9% by weight, slurry viscosity 100cp, geometric mean diameter of petroleum coke 9μ, and geometric standard deviation σg = 3.5.
supplied. Also, coarsely crushed solid fuel (B) with the properties listed in Table 1.
(Undeashed Walara charcoal, geometric mean diameter approximately 1mm) 21.8
Kg/hr is introduced into the wet crusher 11 for simultaneous mixing and crushing (average residence time 0.2 hours), solid fuel (mixture of petroleum coke and Wallara coal) concentration 71.6
A solid fuel-water slurry was obtained with a slurry viscosity of 1140 cp, a solid fuel geometric mean diameter of 24 μ, and a geometric standard deviation σg = 6.3. Note that Table 2 summarizes the manufacturing conditions and results. Example 2 Example 1 was carried out using deashed Wallara charcoal (geometric mean diameter of about 1 mm) as the solid fuel (A) and non-deashed Wallara charcoal (geometric mean diameter of about 1 mm) as the solid fuel (B). Using the same apparatus and method, a solid fuel-water slurry with a concentration of 72.6% by weight, a slurry viscosity of 1000 cp, a geometric mean solid fuel diameter of 50 μm, and a geometric standard deviation σg = 6.7 was obtained. Details of the manufacturing conditions and results of the solid fuel-water slurry are shown in Table 2. Comparative Example 1 A solid fuel with a low ash content was not used as the solid fuel (A), and undeashed Wallara charcoal (geometric mean diameter of about 1 mm) was used as both the solid fuel (A) and the solid fuel (B), The experiment was carried out using the same equipment and method as in Example 1, aiming at a solid fuel-water slurry concentration of 72%, but the viscosity of the solid fuel-water slurry was significantly high in the second step.
Furthermore, since there was no fluidity, mixing and pulverizing operations using the wet pulverizer 11 were not possible. Therefore, the amount of water supplied in the first step was increased to achieve a concentration of 67.4% by weight.
Slurry viscosity 2200cp, solid fuel geometric mean diameter 25μ,
A solid fuel-water slurry with a geometric standard deviation σg = 6.8 was obtained. Details of the manufacturing conditions and results of the solid fuel-water slurry are shown in Table 2. Comparative Example 2 The same solid fuel (A) and solid fuel (B) as in Example 1 were used, and the first step was carried out using the same apparatus and method as in Example 1. Wet pulverization in the second step was carried out for a longer time than in Example 1 to obtain a solid fuel-water slurry having a solid fuel concentration of 69% by weight, a solid fuel geometric mean diameter of 15 μm, and a geometric standard deviation σg = 4.0. Slurry viscosity is
1900cp, and it was not possible to obtain a product with high concentration and low viscosity. Details of the manufacturing conditions and results of the solid fuel-water slurry are shown in Table 2.

【table】 [Brief explanation of drawings]

FIG. 1 is a schematic process diagram showing one embodiment of the present invention. 1... Stirring tank, 6... Wet grinder, 11... Wet grinder, 12... Slurry tank, 13... Hopper, 14... Hopper.

Claims (1)

[Claims] 1. A method for producing a solid fuel-water slurry by wet-pulverizing a solid fuel with water or water and a dispersant, in which a finely powdered solid fuel (A) with a low ash content is used.
is wet-pulverized with water or water and a dispersant so that the solid fuel (A) concentration is 30 to 60% by weight to produce a slurry in which the geometric mean diameter of the solid fuel (A) is adjusted to about 44μ or less. The solid fuel (B), which has a higher ash content than the solid fuel (A), is wet-pulverized together with the slurry produced in the first step. The geometric mean diameter of the solid fuel in the fuel-water slurry is 150μ or less, and the geometric standard deviation σg of the particle size distribution is lognormal distribution.
A method for producing a solid fuel-water slurry, characterized in that the slurry is adjusted to have a value in the range of 6.0 to 12. 2. Claim 1, wherein the solid fuel (A) with a low ash content is petroleum coke or deashed coal, and the solid fuel (B) with a high ash content is non-deashed coal. A method for producing a solid fuel-water slurry.