RU2317319C1 - Fuel suspension preparation process - Google Patents

Abstract

FIELD: coal processing industry.

SUBSTANCE: invention relates to processes of obtaining liquid fuel, in particular to preparation of water-coal fuel intended for hydro-transportation and direct combustion. Process is accomplished by grinding starting material and homogenizing it in dispersion medium consisting of mixture of fine and coarse coal fractions , the former being preliminarily ground with dispersion medium in dispersers operated at power intensity 0.2-1.5 kW/L.

EFFECT: enabled preparation of low-viscosity high-concentration suspension with high content of solid phase.

5 cl, 5 ex

Description

The invention relates to methods for producing liquid fuel, in particular to methods for the preparation of water-coal fuel (HLF), intended for hydrotransport and direct combustion.

A known method of producing water-coal fuel, including preliminary grinding of coal to particles of 6 mm in size, wet fine grinding to obtain a suspension with a particle size of 20 microns, co-grinding this suspension with crushed hard coal to obtain a coarse fraction with a particle size of 60-300 microns, coal supplied to wet fine grinding, a mixture of brown and hard coal is used, and the resulting suspension is divided into two streams, one of which is fed to co-grinding with crushed hard coal, and the second to a homogenizer to obtain the target product (RF patent No. 1796663 A1, class C10L 1/32, publ. 23.02.93).

However, the obtained coal-water fuel without preheating cannot be supplied to direct combustion due to insufficiently high thermal properties.

Closer to the claimed invention in technical essence and the achieved result is a method of producing water-carbon fuel based on a mixture of two types of coal, including their preliminary grinding to a particle size of not more than 6 mm Next, part of the crushed coal is ground with water in the presence of a plasticizer to obtain a suspension with a particle size of not more than 20 microns. The rest of the crushed brown (or stone) coal and / or anthracite is crushed to obtain a coarse fraction with a particle size of 60-300 μm, mixed with a fine fraction first in a coarse mill, and then in a homogenizer to obtain the finished product (RF patent No. 2074885, C. C10L 1/32, publ. 10.03.97).

However, the known method does not allow to obtain fuel suspensions, ready for transportation, with a reduced viscosity, high content of coal particles with high stability to delamination.

The aim of the claimed invention is to obtain water-coal suspensions of low viscosity, ready for transportation, with a high content of coal particles with high stability to delamination.

This goal is achieved by a method of producing a fuel suspension from coal by grinding and homogenizing a mixture of fine and coarse fractions in a dispersion medium, namely, that a thin fraction is preliminarily ground with a dispersion medium in dispersants with a high energy intensity of 0.2-1.5 kW / l. As the dispersion medium, any liquids can be used, for example water, oil or coal residual fractions (sludge), or mixtures thereof with water.

When using water as a dispersion medium, fine fraction grinding is preferably carried out with the addition of any known surfactant used in the field of preparation of water-coal suspensions in an amount of up to 2% by weight of coal with a ratio of coal to water equal to 1: 7 to 1: 2.

When using an oil or coal residual fraction as a dispersion medium, it is preferable to grind the fine coal fraction at a ratio of the mass of coal and dispersion medium from 1: 1.5 to 1: 2.2

When a mixture of an oil or coal residual fraction with water is used as a dispersion medium, the fine fraction is ground at a ratio of the mass of coal and dispersion medium from 1: 0.7 to 1: 1 with an oil or residual coal fraction in water up to 70%.

As coals any coal can be used: stone, brown, anthracite, etc.

The dispersion of a fine fraction with an energy intensity of 0.2-1.5 kW / l is carried out in vibratory mills, roller mills and attritors. The energy costs for pre-grinding the fine fraction in these devices are 50-150 kW · h / t of coal.

The method is as follows.

The initial coal is pre-milled to a particle size of not more than 6 mm in any grinding device. Then the crushed product is divided into a fine fraction (less than 50 microns) and a coarse fraction (up to 300 microns). The fine fraction is mixed with a dispersion medium (water, oil or coal residual fraction or a mixture of the latter with water) in predetermined proportions and fed for additional grinding to a dispersant with a high energy intensity of 0.5-1.5 kW / l. The resulting suspension is mixed with the coarse fraction in predetermined proportions and subjected to subsequent homogenization and grinding in any effective grinding device, for example, a dispersant-cavitator, a vibration mill, a disintegrator, etc. If necessary, surfactants can be introduced into the dispersants at both stages.

The invention is illustrated by the following examples.

Example 1

Brown coal is taken and crushed to a particle size of not more than 6 mm in a mechanical dispersant. Then the crushed product is crushed in a rod mill to a dispersion of 95% less than 300 microns. This product is separated into a fine fraction (less than 50 microns) and a coarse fraction (rest). The fine fraction is mixed with a dispersion medium - oil fraction (fuel oil) in a mass ratio of coal - fuel oil 1: 1.5 and served for additional grinding in a roller mill with an energy intensity of 1.5 kW / l. The resulting suspension is mixed with the coarse fraction in predetermined proportions and subjected to subsequent homogenization and grinding in a dispersant-cavitator.

The result is a fuel suspension with a content of coal particles up to 70 wt.%, A viscosity of 6 Pa · s and resistance to delamination for more than 10 days.

Example 2

Coal is pre-crushed to a particle size of not more than 6 mm in a hammer mill. Then the crushed product is crushed in a rod mill to a dispersion of 95% less than 300 microns. This product is separated into a fine fraction (less than 50 microns) and a coarse fraction (rest). The fine fraction is mixed with the coal residual fraction (coal sludge) in a mass ratio of coal - sludge 1: 2.2 and fed for additional grinding in a vibrating mill with an energy intensity of 0.2 kW / l. The resulting suspension is mixed with the coarse fraction in predetermined proportions and subjected to subsequent homogenization and grinding in a disintegrator.

The result is a fuel suspension with a content of coal particles up to 75 wt.%, A viscosity of 7 Pa · s and a stability of more than 12 days.

Example 3

Anthracite is pre-crushed to a particle size of not more than 6 mm in a hammer mill. Then the crushed product is crushed in a rod mill to a dispersion of 95% less than 300 microns. It is possible to use screenings of anthracite block - a sieve fraction according to a screen of 300 microns. Such a product is divided into a fine fraction (less than 50 microns) and a coarse fraction (rest). The fine fraction is mixed with water in a mass ratio of coal - water 1: 2.0, with 2% wt. Surfactant - Na lignosulfonate and served for additional grinding in an attritor with an energy intensity of 0.75 kW / L. The resulting suspension is mixed with the coarse fraction in predetermined proportions and subjected to subsequent homogenization and grinding in a disintegrator.

The result is a fuel suspension with a content of coal particles up to 65 wt.%, A viscosity of 3.5 Pa · s and a stability of more than 12 days.

Example 4

Brown coal is ground to a particle size of not more than 6 mm in a hammer mill. Then the crushed product is crushed similarly to the previous examples and divided into a fine fraction (less than 50 μm) and a coarse fraction (the rest). A fine fraction is mixed with water in a mass ratio of coal - water 1: 1, with 1% wt. coal with a non-inogenous surfactant - polyoxyethylenenonylphenyl ether and fed for additional grinding to a roller mill with an energy intensity of 0.75 kW / l. The resulting suspension is mixed with the coarse fraction in predetermined proportions and subjected to subsequent homogenization and grinding in a disintegrator.

The result is a fuel suspension with a content of coal particles of up to 75 wt.%, A viscosity of 11 Pa · s and a stability of more than 20 days.

Example 5

Coal is ground to a particle size of not more than 6 mm in a screen. Then the crushed product is crushed similarly to the previous examples and divided into a fine fraction (less than 50 μm) and a coarse fraction (the rest). The fine fraction is mixed with a mixture of the oil fraction with water (fraction to water ratio 1: 1). The ratio of the fine coal fraction to the dispersion medium is 1: 1, and it is fed for additional grinding to a vibratory mill with an energy intensity of 1.0 kW / l. The resulting suspension is mixed with the coarse fraction in predetermined proportions and subjected to subsequent homogenization and grinding in a cavitation mill. The result is a fuel suspension with a content of coal particles of up to 60% wt., Viscosity up to 4 Pa · s and stability of more than 5-6 days.

From a comparative analysis of the claimed invention with known methods, it follows that the proposed method allows to obtain a highly concentrated emulsion of low viscosity with a high solids content (up to 70 wt.%), Which helps to facilitate its transportation, as well as having high stability for a long shelf life.

Claims (5)

1. A method of producing a fuel suspension by grinding and homogenizing a mixture of fine and coarse coal fractions in a dispersion medium, characterized in that the fine fraction is preliminarily ground with a dispersion medium in dispersants with an energy intensity of 0.2-1.5 kW / l. 2. The method according to claim 1, characterized in that any liquid, for example water, oil or coal residual fractions, or mixtures thereof with water, is used as the dispersion medium. 3. The method according to claim 1 or 2, characterized in that when using water as a dispersion medium, the fine fraction is ground with the addition of a surfactant in an amount of up to 2% by weight of coal with a ratio of coal and water from 1: 7 to 1: 2. 4. The method according to claim 1 or 2, characterized in that when using oil or coal residual fractions as the dispersion medium, the fine coal fraction is ground at a ratio of the mass of coal and the dispersion medium from 1: 1.5 to 1: 2.2. 5. The method according to claim 1 or 2, characterized in that when using a mixture of oil or coal residual fraction with water as a dispersion medium, the fine fraction is ground at a ratio of the mass of coal and dispersion medium from 1: 0.7 to 1: 1 at the content of oil or residual coal fractions in water up to 70%.