RU2126034C1 - Method for producing briquettes of brown coal with reduced discharge of sulphur oxide in burning - Google Patents

Abstract

FIELD: processing of coal. SUBSTANCE: according to method, raw brown coal is mixed with water suspension of calcium-containing additive. Also added is coke made from conventional coal or brown coal with particle size not less than 0.25 mm or added are coal briquette fines after mixing of brown coal with calcium-containing additive. Adding of fines should be continued during 80-90% of total mixing time. Coke made from conventional coal or brown coal is added in amount of 5-15% of mass of raw coal and calcium-containing additive. Used is water suspension containing 3-3.5% of slaked lime. Added to mixture of brown coal and suspension is water in amount of 5-10% of mass of raw coal. EFFECT: higher efficiency. 3 cl, 1 ex

Description

 The invention relates to methods for the production of brown coal briquettes with a reduced emission of sulfur oxide during combustion by introducing additives that bind sulfur, especially slaked lime or limestone.

 A known method of binding sulfur contained in brown coal in solid combustion residues, based on the use of sulfur-binding substances, mainly CaO or MgO, while crushed and sometimes pre-dried brown coal and sulfur-binding substance are mixed to a state in which the substance is in a mixture is in dispersed form (DE 3319086, C 10 L 10/04, 12/06/84).

 The disadvantage of this method is that with a large number of additives that bind sulfur, sulfur oxide emissions are quite high.

 A known method of bonding part of sulfur from coal or mixtures of bituminous and brown coal, in which coal or mixtures of brown and bituminous coal is mixed with a substance that binds sulfur, to the state in which this substance is present in the final mixture in finely divided form (DE 3326826 , C 10 L, 10/04, 02/14/85).

 The disadvantage of this method is the relatively high emission of sulfur oxide.

 A known method of burning to reduce the content of sulfur oxide in the exhaust gas, in which, in addition to sulfur-binding substances, brown coal is injected with combustible substances with higher ignition temperatures and combustion rates, and then briquettes are pressed (DE 4039821, C 10 L 5/04, 01/30/92). In this case, optimal combustion conditions could not be achieved.

 A known method of binding acidic harmful substances during combustion in enterprises and power plants, in which a clean solution is added to the fuel before and / or during and after grinding, which contains highly concentrated calcium ions that are bound in the liquid phase in acids or their salts (DE 3309911, C 10 L 10/04).

 The disadvantage of this method is that the material thus obtained cannot be used for the preparation of briquettes.

 A known method of producing briquettes from brown coal with a reduced emission of sulfur oxide during combustion, comprising adding brown coal with 3-5 wt. % sulfur-binding calcium - containing additives, 7-20 wt.% petroleum coke, 7-20 wt. % anthracite (coal) - i.e. combustible, inert from the point of view of sulfur binding, drying the mixture and subsequent briquetting (DE 4140267, C 10 L 10/04, 06/17/92). This technical solution is taken as a prototype.

 However, the prototype has the same disadvantages as its analogues, namely the emission of sulfur oxide, although with a small percentage, occurs.

 The technical result of the invention is a method for the production of briquettes from brown coal, in which there is a complete binding of sulfur in the ash during combustion and the possibility of briquetting fuel.

 The technical result is achieved by the fact that in the method for producing briquettes with a reduced emission of sulfur oxide during combustion, comprising mixing crude brown coal with a sulfur-binding calcium-containing additive, adding a combustible substance inert to sulfur binding, drying the mixture and briquetting, use an inert combustible substance to bind sulfur coke from coal or brown coal with a particle size of less than 0.25 mm or briquette coal fines, which are added after mixing brown coal with a calcium-containing additive in during 80-90% of the total mixing time, and the calcium-containing additive is introduced in the form of an aqueous suspension, while coke from stone or brown coal is added in an amount of 5-15% by weight of crude brown coal and calcium-containing additives; calcium-containing additive in the form of slaked lime slurry containing 3.0-3.5% slaked lime by weight of dry coal; in a mixture of brown coal with a suspension of calcium-containing additives add water in an amount of from 5 to 10% by weight of crude brown coal.

 As an alternative to coke from coal, it is possible to use briquettes from coal dust or from various combustible substances inert from the point of view of sulfur binding, while it is possible to vary both the properties of the briquetting mixture and the possibility of affecting the fuel performance of the briquettes. Suitable combustible substances that are inert from the point of view of sulfur binding are not amenable to per se or are very poorly succumb to briquetting.

 Saturation of raw brown coal with calcium ions occurs by adding slaked lime slurry during an intensive mixing process with a high degree of grinding.

 Especially suitable for this are mixers, through which a high effect of the incorporation of calcium ions into the particles is maintained. With the help of a mixer, uniform grinding and re-agglomeration of the entire mixture is achieved and, thus, a high degree of stability of the mixture.

 With regard to reducing the ash content in the combustion residues, the preferred amount of lime in the raw coal mixture is from 3.0 to 3.5% by weight of dry coal. To create an optimal environment from the point of view of sulfur binding through the distribution of calcium ions inside the particles, the introduction of 5 to 10% water is optimal, while the percentage parts relate to raw coal with additives.

 Example. Crude brown coal with a sulfur content of 3%, a content of (ash) of 10.3% and a water content of 51% is intensively mixed in a mixer with a slurry of slaked lime. Water is added to the suspension coal. After mixing for 90% of the total mixing time - for 90 s, ground brown coke is added as a combustible substance to particles of 0.25 mm. The mixing time for producing coke flour is 10 s. The mixture is dried to a moisture content of 20% and briquetted with a pressure of 100 MPa. The result is briquettes with a strength of 17 MPa. Briquettes are burned in small plants with a low sulfur oxide emission, which corresponds to an equivalent sulfur content of 5%.

 By adding slaked lime, the content of ash (ash) in the briquettes increases to 14.6%.

 Specific examples.

 Indication of numbers in the example applies in parts of mass (kg, t).

This calculation follows:
97.6 kg of raw coal - = 87.8%
3.5 kg of slaked lime (dry) - = 3.2%
10.0 kg of water - = 9.0%
111.0 kg of the mixture - = 100.0%
To this mixture, 7.7 kg of brown coal coke dust is still added to the mixer.

 Additional example.

Initial parameters:
The amount of raw coal - 200.00 t
Total sulfur content (without water) - 3.50%
Crude coal water content - 52.00%
The solids content in the suspension is 25.00%
The content of coke dust - 7.50%
Ca (OH) ₂ - the content of slaked lime - 97.00%
Dosage result:
The amount of slaked lime (dry) - 5.60 tons
The amount of suspension - 22.40 t
The amount of coke dust - 15.42 tons
Additive - the amount of raw coal - 237.80 tons
or
200.00 tons of raw coal - = 89.9%
5.6 tons of slaked lime (dry) - = 2.5%
16.8 tons of water - = 7.6%
Total
222.4 t - 100.0% p

Claims (4)

 1. A method of producing briquettes with a reduced emission of sulfur oxide during combustion, comprising mixing crude brown coal with a sulfur-binding calcium-containing additive, adding a sulfur-binding combustible substance, drying the mixture and briquetting, characterized in that coke is used as an inert sulfur-binding combustible substance from coal or brown coal with a particle size of less than 0.25 mm or briquette coal fines, which are added after mixing brown coal with a calcium-containing additive for 80 - 90% of the total mixing time, and the calcium-containing additive is administered in suspension.  2. The method according to p. 1, characterized in that the coke from coal or brown coal is added in an amount of 5 to 15% by weight of raw coal and calcium-containing additives.  3. The method according to claims 1 and 2, characterized in that the calcium-containing additive is introduced in the form of a slaked lime suspension containing 3.0 - 3.5% slaked lime by weight of dry coal.  4. The method according to claims 1 to 3, characterized in that water is added to the mixture of brown coal with a suspension of calcium-containing additives in an amount of 5 to 10% by weight of the raw coal.