JPH0222795B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method for producing a low viscosity coal-water slurry containing a high proportion of coal with a low water content and low ash content.

In recent years, coal has been reconsidered as an energy source. However, unlike petroleum, coal is in a solid state, so it is not only difficult to transport and handle compared to petroleum, but also has the major drawback of containing a considerable amount of ash. Therefore, in order to facilitate transport and handling, and even to make a fluid fuel, coal is pulverized and dispersed in water.
Various methods have been proposed, such as making a water slurry and dispersing coal in hydrocarbon oil (generally heavy oil) to make a coal and oil mixture (COM). Various methods have also been proposed.

However, COM uses more heavy oil than coal, and is not fully satisfactory as an energy alternative to oil. Also, unlike COM, coal-water slurry has the advantage that it does not require the use of large amounts of heavy oil, but in conventional methods, if you try to contain a high proportion of coal, it will thicken significantly and lose fluidity. Because of this, generally only products with a high water content can be obtained, and many are unsuitable as fluid fuels.

In view of these circumstances, the inventors aimed to produce a coal-water slurry with low viscosity and excellent fluidity even when containing a high proportion of coal, and to produce a coal-water slurry with a low ash content. For this purpose, we conducted intensive research on turning coal into water slurry. As a result, when water and a specific surfactant are mixed with the agglomerates obtained by treating coal in a specific way, it is found that even if the amount of water used is small and the coal content is maintained at a high value, about 1000 cp The present invention was based on the discovery that the following (see Example 1 below) can easily produce a highly concentrated coal-water slurry with low viscosity and low ash content.

This invention uses pulverized coal containing 90% by weight or more of particles with a particle size of 149 microns or less, and whose particle size distribution is in the range of 4 to 12 with a geometric standard deviation σg in a lognormal distribution, by using hydrocarbon oil and water. process,
To the resulting aggregate of pulverized coal and hydrocarbon oil, 25 to 60 parts by weight of water and an anionic dispersant surfactant are added to 100 parts by weight of the aggregate (in terms of dry matter).
The present invention relates to a method for producing a highly concentrated coal-water slurry characterized by mixing 0.1 to 2 parts by weight and 0.1 to 2 parts by weight of a nonionic surfactant having an HLB of 13 or more.

In this invention, the method of treating pulverized coal with hydrocarbon oil and water is not particularly limited as long as an aggregate of pulverized coal and hydrocarbon oil is obtained, but in general, pulverized coal, hydrocarbon oil and water are used. Furthermore, a method of mixing a surfactant is adopted. The mixing produces an aggregate of pulverized coal and hydrocarbon oil, which is separated from the mother liquor.
When mixing, 100 parts by weight of pulverized coal, 1 to 20 parts by weight of hydrocarbon oil, 300 to 1000 parts by weight of water, and a surfactant in an amount of 10 to 2000 ppm based on the water are mixed. is preferred. By mixing the pulverized coal and hydrocarbon oil in these ratios, the rate of aggregation of the pulverized coal and hydrocarbon oil is high, and an aggregate of the pulverized coal and hydrocarbon oil with a low ash content and excellent separability from the mother liquor is produced. Separation from the mother liquor yields an aggregate of pulverized coal and hydrocarbon oil suitable for producing a concentrated coal-water slurry.

The hydrocarbon oil used in producing the aggregate of pulverized coal and hydrocarbon oil can be arbitrarily selected from various hydrocarbon oils obtained from petroleum, tar sands, and coal. Examples of preferred hydrocarbon oils include heavy refined petroleum fractions, heavy gasified oils,
Mention may be made of kerosene, residual oil and coal tar. Particularly preferred are heavy oils that are easily available and inexpensive. In addition, as a surfactant at that time, one having foaming properties or permeability is suitable, and a nonionic surfactant with an HLB of 7 to 17 or an anionic surfactant that promotes permeability is preferable. Specifically, alkylbenzene sulfonate, sodium polyoxyethylene alkylphenol ether sulfate, sodium lauryl sulfate, ammonium lauryl sulfate, polyoxyethylene stearate, polyoxyethylene sorbitan monostearate, polyoxyethylene sorbitan tristearate. , polyoxyethylene lauryl alcohol,
Examples include polyoxyethylene nonylphenol ether and polyoxyethylene lauryl ether.

It is also possible to use only one kind of surfactant, and it is also possible to use two or more kinds in combination. The surfactant is added in an amount of 10 to 2000 ppm (preferably 80 to 800 ppm) based on water as described above. If the amount is less than 10ppm, the effect of surfactant addition will not be apparent, and
If the amount exceeds 2000 ppm, the surface tension of water will drop significantly and the formation of aggregates will be adversely affected. Mixing a surfactant when generating aggregates of pulverized coal and hydrocarbons has the following effects.

(a) Helps disperse pulverized coal (coal particles) into water;
Promotes ash removal.

(b) Assist in the dispersion of hydrocarbon oils into water.

(c) Facilitates homogeneous contact between coal particles and hydrocarbon oil, promoting the formation of homogeneous agglomerates.

(d) Promote phase separation between the phase of the aggregate of pulverized coal and hydrocarbon oil and the aqueous phase to prevent the aggregate of pulverized coal and hydrocarbon oil from floating.

Furthermore, when inorganic salts are added together with the surfactant when pulverized coal is treated with hydrocarbon oil and water to obtain aggregates, the effect of the addition of the surfactant is enhanced. The inorganic salts are preferably water-soluble and alkaline. Aggregates of pulverized coal and hydrocarbon oil are difficult to form at pH 6 or below;
Stable aggregates can easily be obtained with the above conditions. Therefore, by using a water-soluble inorganic salt exhibiting alkalinity in combination with a surfactant, it is possible to improve the ash removal rate and the ability to separate aggregates. Examples of preferred inorganic salts include phosphates such as sodium tripolyphosphate, sodium pyrophosphate, and sodium hexametaphosphate; carbonates such as sodium carbonate and sodium bicarbonate; silicates such as sodium orthosilicate and sodium metasilicate; and Mention may be made of alkaline salts such as the sodium salt of CMC. Moreover, neutral salts such as sodium chloride and sodium sulfate can also be used alone or in combination with the above-mentioned alkaline salts. Particularly preferred inorganic salts are phosphates. The amount of inorganic salts added is 10 to 5000 ppm relative to water.
The amount is appropriate.

In this invention, the type of pulverized coal is not particularly limited, and examples include lignite, subbituminous coal, bituminous coal, anthracite, coke, and mixtures thereof, but highly fluid, low viscosity, highly concentrated coal - In order to produce water slurry and to accelerate the formation rate of aggregates when obtaining aggregates of pulverized coal and hydrocarbon oil, 90% by weight of pulverized coal should have a particle size of 149 microns or less. It is preferable to use a particle having the above properties and a particle size distribution having a geometric standard deviation σg of lognormal distribution in a range of about 4 to 12. Geometric standard deviation (σg) is the geometric mean diameter and cumulative passing weight%
is equivalent to 15.87% of the particle size (geometric mean diameter/
Particle size corresponding to 15.87% of cumulative passing weight) σg ₁ , ratio of particle size corresponding to cumulative passing weight% of 84.13% to geometric mean diameter (particle size corresponding to 84.13% of cumulative passing weight/geometric mean diameter) Arithmetic mean with σg ₂ (σg ₁ + σg ₂ /
2), and the terms geometric mean diameter and geometric standard deviation are terms commonly used to define the particle size of powder and its distribution. Note that the geometric mean diameter is a particle diameter corresponding to a cumulative passing weight% of 50%.

In this invention, after treating pulverized coal with hydrocarbon oil and water and separating the resulting aggregates of pulverized coal and hydrocarbon oil from the mother liquor, water, an anionic dispersant surfactant and HLB Mix a nonionic surfactant with a surfactant of 13 or more. The amount of water to be mixed is preferably as small as possible in order to produce a highly concentrated coal-water slurry, but considering fluidity, the amount of water to be mixed is 25 parts by weight for 100 parts by weight of aggregates of pulverized coal and hydrocarbon oil. ~60 parts by weight. In addition, surfactants with anionic dispersibility and HLB
For nonionic surfactants of 13 or more, it is necessary to use both of these in combination, and it is difficult to achieve the desired purpose using only one of them. The amount of the surfactant used is 0.1 to 2 parts by weight per 100 parts by weight of the aggregate of pulverized coal and hydrocarbon oil, and these surfactants are generally used after being dissolved in the water. These surfactants have a great effect on improving the fluidity, stability, etc. of highly concentrated coal-water slurry. If the amount of surfactant used is too small, the added effect will not be sufficient,
If the amount used is too large, there will be no particular effect, so the amount used is preferably within the above range.

Examples of anionic dispersive surfactants that are mixed with water into aggregates of pulverized coal and hydrocarbon oil include sulfonated polycyclic aromatic compounds having hydrocarbon groups, salts thereof, or formalin thereof. Although condensates may be used, the most favorable results are obtained with sulfonates of coal extracts. The sulfonate of coal extract has a good adsorption property to the pulverized coal in the aggregate, so it has a higher concentration when producing coal-water slurry than when using other anionic surfactants with dispersibility. It has the advantage that the mixing and stirring time is short and the stability of the slurry is good. As a sulfonate of coal extract, coal is
The coal extract obtained by extraction at a temperature of 500 °C using a solvent with a critical temperature lower than its extraction temperature and at a pressure higher than its critical pressure is sulfonated and then using an alkalizing agent. Those obtained by neutralization are preferred. The above-mentioned solvents include aromatic hydrocarbons such as benzene, toluene, o-xylene, m-xylene, p-xylene, xylene mixtures, ethylbenzene, propylbenzene, and alicyclic carbon atoms having 5 or more carbon atoms such as cyclopentane and cyclohexane. Examples include hydrogen, aliphatic hydrocarbons having 6 or more carbon atoms such as hexane, heptane, and nonane, aliphatic amines such as methylamine, ethylamine, and dimethylamine, and heterocyclic compounds such as pyridine. Hydrocarbons are preferred. For the 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.

In addition, the other nonionic surfactant with an HLB of 13 or more that is mixed with water into the aggregate of pulverized coal and hydrocarbon oil is preferably one that corresponds to an emulsifier or a solubilizer. As polyoxyethylene stearate,
Polyoxyethylene sorbitan monostearate, polyoxyethylene sorbitan tristearate, polyoxyethylene lauryl alcohol, polyoxyethylene nonylphenol ether, polyoxyethylene lauryl ether, etc., as well as ethylene glycol, propylene glycol, propanediol, butane Examples include diol, polyvinyl alcohol, glycerin, octyl alcohol, decyl alcohol, lauryl alcohol, cetyl alcohol, and stearyl alcohol, and one or more of these may be used.

Details of one representative embodiment of the method for producing a highly concentrated coal-water slurry of the present invention are as follows.

100 parts by weight of pulverized coal in which 90% by weight or more is 149 microns or less, and the particle size distribution is in the range of about 4 to 12 with a geometric standard deviation σg in a lognormal distribution,
Mix 1 to 20 parts by weight of hydrocarbon oil, 300 to 1000 parts by weight of water, and a surfactant in an amount of 10 to 2000 ppm based on the water to form an aggregate of pulverized coal and hydrocarbon oil. After separating the aggregates, 25 to 60 parts by weight of water per 100 parts by weight of the aggregates (in terms of dry matter);
Surfactant with anionic dispersibility 0.1-2
Parts by weight (preferably sulfonate of coal extract)
0.1 to 2 parts by weight) and 0.1 to 2 parts by weight of a nonionic surfactant having an HLB of 13 or more.

Next, the present invention will be explained by showing examples and comparative examples. The pulverized coal used in each example was prepared as follows.

Pulverized coal A: Australian coal (ash content 12.3% by weight) was wet-milled for 10 hours in a ball mill to produce pulverized coal with an average particle size of 7 microns.Pulverized coal B: Australian coal (ash content 12.3% by weight) was wet-milled in a ball mill for 1 hour to produce pulverized coal. Pulverized coal with a diameter of 30 microns Pulverized coal C: Australian coal is washed with a heavy liquid with a specific gravity of 1.35,
Pulverized coal with an ash content of 4% by weight and an average particle size of 90 microns was obtained by wet-pulverizing the obtained precision for 0.5 hours Example 1 Pulverized coal (average grain Add 800g of water to 100g of diameter 14μ, 95% by weight of 14.9μ or less, geometric standard deviation 6.3),
Further, sodium polyoxyethylene alkyl phenol ether sulfate was added to water at a ratio of 385 ppm and sodium tripolyphosphate was added at a ratio of 385 ppm, and the mixture was stirred at a rotational speed of 1200 PPM for about 5 minutes.
A mixed suspension of pulverized coal and water was made.

Next, 6 g of C heavy oil was added to the mixed suspension and stirred for 10 minutes, and the resulting aggregates of pulverized coal and C heavy oil were separated and collected. A part of the aggregate is used as an analysis sample,
After drying (105°C, 4 hours), the ash content in the dried product was measured and found to be 3.1% by weight.

Next, water in which calcium sulfonate of coal extract and polyoxyethylene nonylphenol ether (HLB 17.8) were dissolved was added to the aggregate of pulverized coal and C heavy oil, so that the weight ratio of aggregate (in terms of dry matter) to water was The mixture was added at a ratio of 70:30 and stirred by hand for about 5 minutes to obtain a low viscosity coal-water slurry. The viscosity of the slurry was measured using a B-type viscometer (measured at 12 RPM using a No. 3 rotor manufactured by Tokyo Keiki Co., Ltd.) and found to be 900 cp.

In addition, calcium sulfonate from coal extract is
It was prepared as follows according to the method described in Example 1 of Japanese Patent Application No. 56-192965.

"Manufacture of coal extract" Miike charcoal crushed to a particle size of 1 mm pass 100% (moisture 1.3%, ash content 20.4
%, volatile content 37.7%, fixed carbon 38.0%) and 300 g of toluene were placed in an autoclave with an internal volume of 0.5 and equipped with a stirrer, and the inside of the autoclave was replaced with nitrogen gas to sufficiently remove the air inside. , sealed.
Heat the autoclave in an electric furnace while stirring the contents, and bring the temperature of the autoclave up over an hour.
The temperature was raised to 400℃. This temperature was further maintained for 1 hour while stirring was continued to extract coal. Next, after the autoclave was cooled to room temperature, the contents were taken out and separated into a solid extraction residue and an extract (filtrate) in the form of a toluene solution using a filter. Next, toluene was evaporated from the filtrate under normal pressure using an evaporator, and then toluene was sufficiently evaporated and removed under reduced pressure to obtain a coal extract. [Sulfonation and Neutralization] 7.0 g of the coal extract obtained as above was dissolved in 50 g of carbon tetrachloride, and the mixture was poured into a 100 ml three-necked flask (equipped with a stirring device, a device capable of cooling evaporated matter, and a dropping funnel). installed). While stirring the contents of the flask, sulfuric anhydride was slowly added dropwise from the dropping funnel. The reaction temperature at this point is
A total of 5.1 g of sulfuric anhydride was added dropwise over 30 minutes while maintaining the temperature at 20°C. After the dropwise addition was completed, the temperature of the flask was raised, and the reaction was carried out for 1 hour at a temperature at which carbon tetrachloride refluxed to effect sulfonation. After refluxing was completed, a vacuum distillation device was attached to the flask to distill off carbon tetrachloride. Water was added to the coal extract sulfonation reaction product remaining as a residue in the flask to make a homogeneous aqueous solution, which was then taken out from the flask. The obtained sulfonation reaction product was
The aqueous solution was placed in a 500 ml beaker, and an aqueous solution of calcium hydroxide was added while stirring to neutralize the pH to 7.0. This neutralized solution was applied to a centrifuge and centrifuged at 2000 rpm for 10 minutes. The supernatant liquid of the centrifuged neutralized liquid was taken out, and water was removed by evaporation using a conventional method to obtain 3.1 g of calcium sulfonate as a coal extract. It was used in an amount of 0.33 parts by weight per 100 parts by weight of the aggregate of pulverized coal and heavy oil C (in terms of dry matter). Further, polyoxyethylene nonylphenol ether was used in an amount of 0.71 parts by weight per 100 parts by weight of the aggregate.

Example 2 The calcium sulfonate in the coal extract of Example 1 was changed to 0.37 parts by weight of naphthalene sulfonic acid formalin condensate, the weight ratio of the aggregate to water was changed to 68:32, and the mixture was stirred at a rotation speed of about 1800 RPM for 3 minutes. A coal-water slurry was produced in the same manner as in Example 1, except for stirring. The viscosity of the resulting slurry was 600 cp.

Example 3 Example 3 except that pulverized coal prepared by mixing pulverized coal A and pulverized coal B at a weight ratio of 7:3 (average particle size 11μ, 98% by weight of 149μ or less, geometric standard deviation 4.5) was used. Prepare an aggregate of pulverized coal and C heavy oil in the same manner as in 1 (ash content measurement result: ash content 5.5% by weight dry matter basis), change the weight ratio of aggregate to water to 68:32, and add sulfone of coal extract. Except for replacing calcium acid with 0.37 parts by weight of sodium sulfonate from coal extract.
A coal-water slurry was produced in the same manner as in Example 1. The viscosity of the resulting slurry was 1400 cp.

Comparative example 1 Pulverized coal A (average particle size 7μ, 149μ or less)
99% by weight, geometric standard deviation 3.2) was used.
An attempt was made to prepare aggregates of pulverized coal and heavy oil C in the same manner as in Example 1, but unlike in Examples 1 and 3, no aggregates were formed even after stirring for 10 minutes after adding heavy oil C. , After stirring for 30 minutes, the pulverized coal and C
Since an aggregate with the heavy oil was formed, this was separated and collected. The aggregates were more difficult to separate than in Examples 1 and 3. The ash content in the aggregate was 3.2% by weight.

Using the aggregates of pulverized coal and C heavy oil obtained in this way, only polyoxyethylene nonyl phenol ether was added as a surfactant to the aggregates.
Highly concentrated coal using 0.71 parts by weight
An attempt was made to produce a water slurry, but when the amount of aggregates was increased to a weight ratio of 55:45 or more, fluidity was lost and it was difficult to form a slurry. In addition,
The viscosity of the slurry in the case of 55:45 was 500 cp.

Claims (1)

[Claims] 1 Pulverized coal with a particle size of 149 microns or less
Aggregates of pulverized coal and hydrocarbon oil obtained by treating 90% by weight or more and having a particle size distribution with a geometric standard deviation σg of lognormal distribution in the range of 4 to 12 with hydrocarbon oil and water. To 100 parts by weight of the aggregate, 25 to 60 parts by weight of water, 0.1 to 2 parts by weight of an anionic dispersing surfactant, and 13 parts by weight of HLB.
A method for producing a highly concentrated coal-water slurry, which comprises mixing 0.1 to 2 parts by weight of the above nonionic surfactant.