RU2268289C1 - Method for production of water-carbon fuel composite - Google Patents

Abstract

FIELD: fuel composite useful in industry, housing and utilities infrastructure, power industry, etc.

SUBSTANCE: claimed method includes preliminary carbon wet grinding, oil agglomeration of obtained water/carbon mixture, separation of oil granulate from waste and water, followed by granulate blending and dispersing with organic component. Preliminary carbon wet grinding is carried out in presence of defecated liquid phase obtained from mechanical granulate dehydration and waste defecation processes, and before blending and dispersing oil granulate is separated to provide 0.1(0.5) mm grade with simultaneous mechanical dehydration of +0.1(0.5) mm grade, wherein blending and dispersing with organic component in presence of plasticizer is carried out using dehydrated granulate of +0.1(0.5) mm grade and suspension of control floating throughproduct concentrate from separation process.

EFFECT: fuel of increased calorific capacity without losses of structural and rheological characteristics and decreased cost.

1 dwg

Description

The invention relates to methods for producing liquid fuel based on coal and water — composite water-coal fuel (WUT) and can be used in the fuel industry, energy, housing and communal services, and other industries.

There is a method of preparing water-coal fuel from raw coal (see 1. Zaydenvarg V.E., Trubetskoy K.N., Murko V.I., Nekhoroshiy I.Kh. Production and use of water-coal fuel. M., Publishing House of the Academy of Mining Sciences , 2001, p.52-56), recommended at the Belovo-Novosibirsk experimental industrial coal pipeline. According to this method, raw coal with an ash content of 10-20% is previously crushed to cl. 0-3 (6) mm, and then it is wet-ground in drum ball and rod mills with the addition of a plasticizer reagent.

There is a method of enrichment of small coals and coal sludge by oil sintering (see 2. Elyashevich AT, Papushin Yu.L., Beletsky BC Enrichment of coal sludge by oil sintering. J.: Coke and Chemistry, 1991, No. 5 , p. 7-9).

According to this method, preliminary wet grinding of coal sludge to cells is performed. 0-0.105 mm. Then, the resulting water-coal suspension undergoes oil sintering. The result is an aqueous mixture of granulate and waste. After mechanical dehydration of the resulting mixture, the dehydrated granulate and the waste hydraulic mixture are separated on the screen. Granulate is the starting material for burning or coking. The hydraulic mixture of waste is sent to the dump.

The closest solution to the technical nature and the achieved result is a method of preparing coal oil granules for burning in a furnace (see 3. A.S. No. 1262204. M.cl F 23 K 1/00. Publ. 07.10.1986 Bull. No. 37). According to this method, oil granulation of coal sludge is carried out, granules are separated from water by mechanical dehydration and subsequent drying, and before being fed into the furnace, the granules are dissolved in an organic solvent, mainly in fuel oil, and fed into the furnace in liquid form.

The disadvantages of analogues and prototype are:

- the use of raw coal;

- ineffective use of the oil agent due to its waste losses

and removable liquid phase during dehydration and thermal drying of the granulate;

- the use of fire and explosive thermal drying of the granulate after mechanical dehydration;

- the high cost of the resulting liquid fuel due to the removal of water using the most expensive method - thermal drying and the need to use a large amount of organic solvent, heated to 100-180 ° C.

The tasks solved by the invention are:

- improving the efficiency of using the oil agent in the oil agglomeration of the source coal or coal sludge and the subsequent preparation of high-quality composite coal-water fuel;

- ensuring fire and explosion safety in the preparation of composite coal-water fuel;

- providing the required values of calorific value and reactivity of composite coal-water fuel while maintaining its structural and rheological characteristics (fluidity and stability);

- reducing the cost of finished composite water-carbon fuel.

The tasks are solved in that the preliminary wet grinding of coal (coal sludge) is carried out in the presence of a clarified liquid phase obtained by mechanical dehydration of the granulate and clarification of waste, and before mixing and dispersing the oil granulate is classified by class. 0.1 (0.5) mm with simultaneous mechanical dehydration of cells. +0.1 (0.5) mm, while dehydrated granulate C. is sent to mix and disperse with an organic component in the presence of a plasticizing reagent. +0.1 (0.5) mm and a suspension of the control flotation concentrate of the under-sieve classification product.

Indeed, the use of the liquid phase obtained by mechanical dehydration of the granulate and clarification of waste at the stage of preliminary wet grinding of coal or coal sludge allows unreacted particles of the oil agent present in the liquid phase to actively interact with new “fresh” surfaces of small coal particles that arise during grinding. As a result, the agglomeration process is intensified, and the efficiency of using the oil agent is increased due to its more complete use and elimination of its discharge with waste.

Classification of the slurry “oil granulate + waste” with simultaneous mechanical dehydration of cl. +0.1 (0.5) mm, while mixing and dispersing with an organic component in the presence of a plasticizer reagent dehydrated granulate class. +0.1 (0.5) mm and suspensions of the control flotation concentrate of the under-sieve classification product ensures the maximum possible degree of use of the oil reagent in the process and the required quality of the resulting composite coal-water fuel. This eliminates the cost of explosive and fire hazardous thermal drying, which determines the low cost of the finished product. In fact, a closed technological scheme for the preparation of composite coal-water fuel is implemented, eliminating the discharge of the oil agent beyond the water-slurry scheme of the fuel production plant. The presence of a plasticizing reagent allows to reduce the content of the aqueous liquid phase in the finished composite HLW to the minimum possible value while maintaining structural and rheological characteristics (fluidity and stability) at the required level.

The separation boundary of the oil granulate, equal to +0.1 (0.5) mm, is due to the upper limit of fineness during preliminary grinding, as well as the best dewatering efficiency of the obtained granulate on a sieving surface. It is proposed to use elastic screening surfaces made of rubber (EPP) as a screening surface. Thus, the selected classification boundary provides, firstly, the passage of all rock particles through a sieve, and secondly, the most efficient extraction and dehydration of the already formed oil granules into the oversize product.

The implementation of the control flotation process of the under-sieve product of the oil granulate + waste slurry classification, on the one hand, allows to increase the yield of the concentrate by returning the granules of oil granules destroyed and semi-destroyed during mechanical dehydration, and, on the other hand, to ensure the supply of residues of the oil agent for preparation composite coal-water fuel.

Mixing and dispersing of oil garnulat cl. +0.1 (0.5) mm and a flotation concentrate of an oversize product with an organic component, as a rule, is carried out in a drum mill of a conventional or vibrating predominantly horizontal type or mechanical dispersant-cavitator. The use of a horizontal ball or rod mill makes it possible to intensify the mixing and dispersion process due to numerous strokes of the grinding media when the mixture moves along the mill drum during its rotation or vibration. These mills are widely used in coal, mining, cement and other industries.

It is also possible to use modern mechanical dispersant-cavitators for mixing and dispersing kg oil granulate. +0.1 (0.5) mm and a flotation concentrate of an under-sieve product with an organic component in the presence of a plasticizer reagent, which makes it possible to efficiently carry out these processes to obtain a well-flowing and stable composite coal-water fuel.

The dehydrated oversize product, containing, as a rule, whole coal-oil granules, is sent for dispersion and mixing with the organic component in the presence of a plasticizing reagent.

The under-sieve product containing dilapidated and destroyed coal-oil granules and wastes is subjected to control flotation, as a result of which the concentrate containing the remains of coal-oil granules, in the form of an oil-water aqueous suspension, is also fed to dispersion and mixing, and the hydraulic mixture with the rock is sent to thicken and clarify. The clarified liquid phase returns to the head of the process - for wet grinding of the original fine coal or coal sludge. As a result, the maximum degree of utilization of the oil agent is ensured and its discharge outside the limits of the fuel preparation installation is excluded. Ultimately, the above operations lead to a reduction in the cost of the finished composite coal-water fuel and an increase in its quality.

As an oil agent, heating oil, flotation reagents AF-2, AAR-1, oil for oiling the mixture, etc. are used.

As reagents, plasticizers are used, as a rule, compositions based on carbon-alkaline reagent (USR) or technical lignosulfonate (LST) [1].

The organic component used is oil, fuel oil, heavy pyrolysis resin, ethyl or methyl alcohols, etc.

The under-sieve product of classification and mechanical dehydration is fed to control flotation, as a result of which unreacted particles of the oil agent, dilapidated and destroyed oil granules (if any) due to the action of supplied air bubbles and, if necessary, a small dose of flotation agent float to the surface and in the form of an aqueous suspension sent for mixing and homogenization with an organic solvent in the presence of a plasticizer reagent. The rock part settled in the flotation machine in the form of a hydraulic mixture is removed for dehydration and clarification. The clarified water goes to the head of the process. Dehydrated rock (waste) is disposed of in a dump.

For mixing and dispersing oil granulate cl. +0.1 (0.5) mm and suspensions of the control flotation concentrate with an organic solvent, these products are fed to a drum mill or mechanical dispersant-cavitator. At the same time, a plasticizer reagent and, if necessary, part of the clarified liquid phase (not shown) are metered into the process.

As a result of intensive mixing and dispersion in a drum mill or mechanical dispersant-cavitator, a finished composite coal-water fuel with the necessary structural and rheological characteristics is formed. This is ensured by the use of an appropriate plasticizer reagent. As mentioned above, the following organic components are used: methyl or ethyl alcohols, fuel oil, oil or heavy pyrolysis resin, etc. Plasticizing reagents, as a rule, are compositions based on carbon-alkaline reagent and technical lignosulfonates.

A method of producing a composite water-carbon fuel is implemented as follows (see drawing).

The original fine coal or coal sludge is ground wet to cells. 0-0.1 (0.5) mm. At the same time, the liquid phase formed during the mechanical dehydration of the granulate and clarification of waste after oil sintering is used as the liquid phase. The resulting water-coal suspension is sent for oil agglomeration to a granulator, where a binder is also added - an oil agent, for example fuel oil. The implementation of oil agglomeration occurs due to the fact that coal particles hydrophobic or hydrophobized during grinding during turbulization in an aqueous medium with a binder (hydrocarbon liquid) form agglomerates consisting of coal particles bound together by a thin film of oil. Gradually, the agglomerates condense, structurally transforming into sufficiently strong and dense granules of predominantly spherical shape.

Coal products float to the surface and are removed along with part of the liquid phase. The main part of the liquid phase is then separated during the classification and mechanical dehydration of the granulate, for example, on a vibrating screen with a mesh (slot) of 0.1 (0.5) mm in size. Mineral hydrophilic particles (waste) are deposited and removed from the granulator in the form of a slurry.

The resulting slurry enters the classification (for example, a vibrating screen equipped with an EPP), which results in the separation of granules and solid particles of the slurry according to class. 0.1 (0.5) mm with simultaneous dehydration of cells. +0.1 (0.5) mm. Oversize product classification in the form of oil granules in the composition of granules cl. +0.1 (0.5) mm, containing pure coal particles, is sent for mixing and dispersion in a drum mill or mechanical dispersant-cavitator. At the same time, an organic component (for example, methyl or ethyl alcohols, fuel oil, oil or a heavy pyrolysis resin), a plasticizer reagent (for example, based on a technical lignosulfonate or carbon-alkaline reagent) and a suspension of a control flotation concentrate of an under-sieve classification product are fed to mixing and dispersing.

As a result of mixing and dispersion of the incoming materials, a composite coal-water fuel is formed, which has the necessary rheological characteristics for hydrotransport, storage and direct combustion in boilers of heat-generating plants. A specific product of control flotation after thickening and dehydration is sent to the dump, and the clarified liquid phase is sent to the head of the process.

Examples of the proposed method for producing composite coal water fuel:

Coal sludge of grades D, SS and T was taken as a feedstock.

Table 1 presents the results of oil sintering pre-crushed to cells. 0.5 mm samples of coal sludge in a core mill with a mass fraction of solid phase of 50% and subsequent classification on a vibrating screen with a mesh size of 0.5 mm. As the liquid phase, a clarified liquid phase was used (the solid content did not exceed 1 g / l).

Table 1 Product name Ash content of the initial product from the mass of sludge,% Type and consumption of oil agent,% Cl. Output +0.5 mm of granulate,% Ash and (humidity) class. +0.5 mm of granulate (including oil agent),% Ash content and (yield) of under-sieve product,% D coal grade sludge 18.3 Fuel oil 10 ÷ 15% 91.3 3.8 (12.5) 65.0 (8.7) SS brand coal slurry 19.9 - // - // - 80.3 6.5 (13.4) 60.2 (19.7) T coal grade sludge 25.0 - // - // - 75.3 6.6 (14.6) 58.9 (24.7)

Table 2 presents the results of the control flotation of the under-sieve product classification and mechanical dehydration.

Table 2 Grade of coal and (ash content) of the under-sieve product of classification and dehydration Control flotation concentrate Waste Exit, % Ash content,% Exit, % Ash content,% D (65.0)
SS (60.2)
T (58.9) 15.3
18.5
18.9 10.1
10,4
11.5 84.7
81.5
91.1 75.1
71.5
62.3

When mixing dehydrated oil granules cl. +0.5 mm with a control flotation concentrate of the under-sieve product, a slight increase in the ash content of the mixture was obtained compared to the ash content of coal-oil granules, respectively, for grade D sludge, the ash content of the mixture was 3.9, SS-6.7, and T-6.9%. However, the ash content of the waste increased significantly. Accordingly, up to 75.1; 71.5 and 62.3%.

Next, a mixture of the oversize product of classification and mechanical dehydration (class +0.1 (0.5) mm) and a suspension of the control flotation concentrate were loaded into a vibratory mill. At the same time, a solution of a plasticizer reagent obtained on the basis of USR (50% USR + 50% Na ₂ CO ₃ ) and organic components alternately: oil, fuel oil, heavy pyrolysis resin, methyl alcohol were also fed into the mill drum. When using methyl alcohol, a reagent-classifier based on LST (75% LST + 25% NaOH) was used. The reagent consumption was 1% of the solid mass of the mixture.

The results of the preparation of composite coal water in a vibratory mill are presented in table 3.

Thus, the above examples of the implementation of the developed method for the preparation of highly reactive coal-water fuel show its technical feasibility and high quality of the resulting fuel.

The feasibility studies show that when using composite water-based fuel based on methyl alcohol, the cost of generating 1 MW of electrical energy is 30-62% lower compared to fuel oil.

Currently, on the basis of the proposed method, a bench-top demonstration unit for the preparation (enrichment) of coal sludge, preparation of composite water-coal fuel based on it, and its combustion in the boiler furnace has been developed and put into operation.

Claims (1)

A method for producing composite coal-water fuel, including preliminary wet grinding of coal, oil agglomeration of the obtained coal-water suspension, separating oil granules from waste and water, mixing and dispersing the granulate with an organic component, characterized in that the preliminary wet grinding of coal is carried out in the presence of a clarified liquid phase obtained with mechanical dehydration of the granulate and clarification of waste, and before mixing and dispersing the oil granulate is classified they are cited according to the class 0.1 (0.5) mm with simultaneous mechanical dehydration of the class +0.1 (0.5) mm, while dehydrated granulate of the class +0.1 is sent to mixing and dispersing with the organic component in the presence of a plasticizing reagent (0.5) mm and a suspension of the control flotation concentrate of the under-sieve product of classification.