JPS58134189A - Solid fuel aqueous suspension and manufacture - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to an aqueous suspension of solid fuel and a process for its preparation, which suspension is extremely stable and can be used as a fuel and can also be gasified.

Recent attempts to replace liquid fuels derived from petroleum with solid fuels have encountered problems unique to solid fuels, namely storage, handling, and usage problems. As a solution to these problems, it has already been proposed to use coal in the form of powder or dispersion, for example. However, powdered coal is highly flammable and explosive, making its handling and use dangerous. On the other hand, a dispersion in which coal is dispersed in a liquid fuel such as fuel oil is similar to petroleum-based fuel.
In addition to storage problems, they generally cannot be transported and cannot be used without preheating. Aqueous suspensions of coal, on the other hand, have a significant advantage because they are not easily flammable when stored and can be used in fuel tanks without preheating.

However, in order to provide this aqueous suspension with storage stability and pumpability equivalent to that of ordinary liquid fuels, and to make it possible to disperse this aqueous suspension in a 9-ner without any particular difficulty, for at least 6 Jl of coal in suspension.
It must be 0 wt%, but it must be 0°.

It has already been proposed to use an aqueous suspension of coal as a fuel in and ζro. Previously proposed aqueous suspensions of this food have been designed to improve their storage stability by adjusting the particle size distribution of coal or coexisting with various additives that act as dispersants. There is. however,
Adjustment of the particle size distribution has the disadvantage that it is relatively expensive, and the information given in the known literature regarding additives for various foods does not allow optically stable suspensions to be obtained.

Here, we have developed an aqueous suspension containing at least 60 wt% solid fuel, having storage stability and transport suitability, and which can be dispersed in a nanoparticle without particular difficulty. developed.

That is, the aqueous suspensions of the present invention contain at least 460 vt.
16 solid fuel, 0.01 to 1 wt% of at least one type of surfactant, 0.01 to 1 wt% of at least one type of dispersant,
01~l wt %, at least one gelling agent
．． 01 to Q, it is characterized by containing 1 wt%.

The solid fuel of the present invention is selected, for example, from coal, lignite, coal pitch, petroleum pitch and mixtures thereof.

As is well known, surfactants are compounds that can change the surface tension of a medium, thus imparting turbidity properties to the medium.7 This agent has hydrophilic and lipophilic groups. The surfactants of the present invention may be anionic (eg, alkali metal salts of alkylarylsulfonic acids) or cationic (eg, quaternary ammonium salts). Preferred surfactants are alkali metal salts of alkylarylsulfonic acids, such as sodium alkylnaphthalenesulfonates.

Dispersants, also called peptizers, are compounds that can generate or increase the charge of PiJll on the surface of solid fuel particles. This therefore promotes the generation of electrical repulsion between the homogeneous fuel particles. As dispersants, alkali metal silicates (especially metasilicates), alkali metal polyphosphates and alkali metal salts of organic iris acids (% polyacrylic #2) are advantageously used.

Although anionic surfactants, particularly alkali metal salts of alkylarylsulfonic acids, have dispersing power, it is not possible to obtain the suspension contemplated by the present invention using these surfactants alone.

Gelling agents are compounds that form thixotrosodic colloidal solutions or suspensions in water.

Therefore, the gelling agent imparts high static viscosity to the solid fuel aqueous suspension without impairing its pumpability or burner dispersibility.

As the gelling agent, cellulose ethers, such as carboxymethylcellulose and methylcellulose, are preferably used.

According to the present invention, f3 Q wt% of solid fuel particles is 8
Preferably, the particles are present in an aqueous suspension with a particle size of 0 micron or less. In fact, if the 8096 particles have a particle size of 80 microns or more, the aqueous suspension will have difficulty in burning it, and more than 80% of the particles will have a particle size of 80 microns or less. If the suspension is present, it will be difficult to transport the suspension.

The present invention also provides a method for preparing a suspension as described above, which method comprises: grinding solid fuel in water; 0.01-1 vt% surfactant in a mixture of
% dispersant, 0.01-G, 1 wt % gelling agent, and further water in an amount such that the amount of solid fuel in the suspension is at least 60 wt % rc.

The solid fuel is preferably pulverized so that its 8Q wt% has a particle size of 80 microns or less.

Preferably, 60% of the solid fuel is added to the amount of water added during the grinding process.
The amount is such that an aqueous suspended temperature source containing ~gQwt can be obtained.

The aqueous suspension of the present invention can also be prepared by dispersing dry homogeneous fuel in water.

Wet grinding is preferred in the present invention. This is because there is no danger of explosion as in the case of dry pulverization, and there is no need to dry the solid fuel beforehand. In addition to this, wet crushing is also done! ,'I
),,jl, The use of a crushing accelerator can also save the energy required for crushing.

The crushing accelerator functions to penetrate into the cracks of the solid fuel and prevent the solid particles from approaching again. Such agents include tetralin, pyridine, ethanolamine, acrylonitrile, orthocyclohexylphenol and sodium silicoaluminate.

Preferred starting materials for preparing the suspensions of the invention are:
Sludge from coal washers, already in crushed form, currently has little use other than as fuel.

An example of a method for preparing the suspension of the present invention is to subject the sludge to purification means such as flotation to remove the non-flammable residue.
The refined sludge is then wet-pulverized until its g Q wt% has a particle size of 80 microns or less, preferably 60 to 80%.
The additives and water described above are added before, after, or during wet milling in a manner that yields ~80 wt% of the final product.

EXAMPLE Sludge obtained from a Frey pump coal (coagulated coal) washer was prepared in the presence of a mixture of 75% light fuel oil and 25% methyl isobutyl carbinol (400 g per ton).
K was selected. After this flotation, the coal was filtered or centrifuged, and then sieved to obtain coal containing 15% water and 6% ash (both based on the weight of dry coal).

This coal was wet-pulverized, and the 8Q wt% of the coal particles was 80
A product with submicron particle size was obtained.

During wet grinding, A, Q, 1 wt% sodium methylene bisnaphthalene sulfonate, Q, 1 wt% sodium metasilicate, C,
0.03 wt% methyl cellulose, 20 coal content 6
An amount of water was added to obtain a 0 wt% mixture.

The resulting suspension was viscous at rest and had high storage stability. The rheogram of this thing has a shear rate of about 2
s″″! The viscosity after 2 minutes at a shear rate of 1 oos-'' was 670 centiboise.

The above product was combusted with a 20-megawatt excess of air in a two-megawatt experimental burner equipped with a burner as shown in French Patent No. 2,054,741.

The thermal combustion efficiency in this case was 80.3%, and when compared with the efficiency of 892% when dry powdered coal was burned under the same conditions, the difference was only 8.9%.

To demonstrate the tu point of the combination of surfactant and dispersant, (a) a suspension containing 60 wt% coal and 0.1 wt% sodium methylene bisnaphthalene sulfonate, Q)) 60 wt% suspension containing coal and Q, jwt- sodium metasilicate, (c) eowtqb
of coal, 0.1 wt% sodium methylene bisnaphthalene sulfonate, and 0.1 wt% sodium metasilicate, respectively, at a shear rate of 3'00.
The viscosity was measured after 2 minutes at s″″1.

According to that, (a) is 6 shi 2 centimeters, and 佽) is 6
70 centimeters: (C) failed with 380 centimeters and 4 issues. Therefore, it can be seen that the combination of two types of additives has a mutually beneficial effect on the viscosity of the suspension.

Claims (1)

[Claims] 1. 0.01 to 1 wt% of at least one surfactant
, at least 1.1 m (7), powder volume 0.01-1
wt% of at least one gelling agent from 0.01 to 0.
An aqueous suspension containing at least @Q wt% solid fuel, each containing 1 wt%. 2. The aqueous suspension according to claim 1, wherein 8·Ovt% of the solid fuel has a particle size of 80 microns or less. -3. The aqueous suspension according to claim 1 or 2, wherein the surfactant is selected from anionic surfactants. 4. The aqueous suspension according to claim 3, wherein the 4,7-ionic surfactant is an alkali metal salt of alkylarylsulfonic acid. 5. The aqueous suspension according to any one of claims 'i-4, wherein the dispersant is an alkali metal salt of citric acid. 6. The aqueous suspension according to any one of Claims 1-@5, characterized in that the gelling agent is cellulose ether. 7. Grinding the solid fuel in water. and 0.01 to 1 wt % surfactant and 0.01 to 1 wt % of a surfactant to the solid fuel and water mixture before or during the grinding.
Add a wt% dispersant and 0.01 to 0.1wt% gelling agent, and add water in an amount such that the amount of solid fuel in the suspension is at least f5Qwt%. A method for producing an aqueous suspension of solid fuel, characterized by: 8. The method of claim 187, wherein the solid fuel is pulverized until its 13 Q wt% has a particle size of 80 microns or less. 9. The method according to claim 7 or 8, characterized in that water is added in such an amount that a suspension having a solid fuel content of 60 to 80 vt% is obtained. 10. 1. Any one of claims 7 to 9, characterized in that the solid fuel is pulverized in the presence of a pulverization accelerator. ! The method described by J.J. 11. Claims vR7 to 7, characterized in that the solid fuel is contained in sludge from a coal washer.
The method according to any one of the items. 12. Prior to crushing, the sludge is reduced to a non-flammable residual amount of 1
The method according to claim 11, wherein the method is purified to 0% or less. 13. The method according to claim 12, wherein the N product is subjected to flotation.