SU1056908A3 - Method for dehydrating low-grade solid fuel - Google Patents

Abstract

A process for the upgrading of low-grade solid fuel by heating at a temperature above 300 DEG C in the presence of water, in which before or during the heating above 300 DEG C acid is added to the fuel.

Description

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The invention relates to a method for treating solid fuels, in particular to methods for dewatering fuels, and can be used in the S coal industry. A known method of dewatering solid fuels includes heating a mixture of solid fuels and water at 300-374s and a pressure that is higher than the water vapor pressure at the heating temperature ij. However, the known method does not provide high calorific value fuels. The aim of the invention is to increase calorific value of fuel by increasing its resin content. The goal has been achieved. According to the method of dewatering solid fuels, including heating the mixture of fuel and water to ZOO-374 ° C, heating is carried out in the presence of an organic acid. The organic acid is added in the quantities necessary to achieve a pH of the mixture in the range from 3.5 to. Moreover, heating is carried out at a pressure below 85 atm. In addition, before heating to 374 ° C, the mixture of fuel, water and organic acid is heated at 240250 ° C and under a pressure that is higher than the pressure of water vapor at the heating temperature, and is separated from the water. The proposed fuel dewatering method is intended for the treatment of low grade fuel, such as biomass, plant material, waste, manure, peat and brown coal. As a rule, this fuel contains a lot of water. Water is partially physically absorbed, partly present in a bound form in helium structures, and partly chemically bound. The fuel also contains many oxygen-containing groups. The calorific value of the fuel can be significantly increased by maximizing the removal of water through the dehydration process and oxygen-containing groups through the decarboxylation process. In the raw state, the fuel may contain tar (tar), which can be separated from the fuel by extraction. Heating topsheva above 300 ° C in some cases increases the amount of spola extracted from low grade solid fuels. The resin, which is a substitute for raw mineral oil, is a valuable material. Selected resin can be divided into fractions by distillation. The amount of resin obtained by heating more than can be significantly increased and at the same time increases the calorific value of solid fuel by lowering the pH of the mixture of fuel and water. According to the proposed method of dewatering a low grade solid fuel, before heating to a temperature above or during heating, acid is added to the mixture of fuel and water. Due to the introduction of more acid. In the dewatering process, 1% of the LOW QUALITY fuel can be converted to tar. At least a portion of the obtained resin is separated from the fuel and is preferably used for granulating or briquetting dry solid fuel, and briquettes having high crush strength are obtained. The dehydrated fuel from which the resin was isolated has a lower calorific value compared to the dehydrated fuel containing the resin. However, this difference in calorific value is significantly offset by the increasing amount of resin produced. In addition, the calorific value of enriched fuel significantly exceeds the calorific value of the initial low-quality solid. fuel. The resulting resin has a highly alphatic character and a low content of polyaromatic components. The nature of the acid added to the mixture of fuel and water is not very important. Organic acids such as lignosulfonic acid are used. Formic acid and acetic acid are very suitable. Example 1. Australian. brown coal (calorific value of 26.7 MJ / kg) with a water content of 60.0 wt.% and an ash content of the order of G, O wt.% is suspended in water (6 parts of water per 10 hours of brown coal), to which technical pure glacial acetic acid is added in an amount that provides a pH of the mixture of fuel and water equal to 3.5 (14 parts of glacial acetic acid per 1000 hours of brown coal), and then the mixture is heated in an autoclave to 8 ° C. / min. Then the autoclave is opened and the water is separated from the coal using a sieve. Processed, dewatered coal contains 15% by weight of water and has a calorific value of 32.1 J / kg. This treated charcoal is extracted with toluene. The amount of tar implanted into the solution during the extraction process is 6.8 wt.% Relative to the amount of brown coal. The calorific value of the extracted dry coal is 29.3 MJ / kg. For comparison, the initial brown coal is subjected to extraction with toluene, the amount of resin recovered during the extraction process is 1.2% of the amount of the original brown coal. For further comparison, the brown coal dehydration described is repeated, except for the addition of glacial acetic acid to the mixture of fuel and water. The limiting yield of the resin during the extraction process is 2.4% of the initial amount of brown coal, and the pH of the mixture after completion of the dewatering process is 7.5. The calorific value of the treated carbon prior to extraction is 31.8 MJ / kg. , Example 2. Cow manure (calorific value of 14.7 MJ is calculated on a material containing water and ash suspended in water, to which is added such a quantity of glacial acetic acid so that the pH of the mixture becomes 4.5. The resulting mixture is heated to In this dewatering process, 40 parts by weight of ash-free and anhydrous coal are obtained for each 100 parts by weight of ashless and anhydrous material present in cow dung, from which 25 are obtained by extraction weight.h tar. Calorific value of coal, calculated on the basis of a material that does not contain moisture and ash before and after extraction, it is 31 and 28.5 MJ / kg, respectively: but with this experiment, except for the introduction of glacial acetic acid (pH of the mixture from cow’s manure in water 7.5) per 100 parts by weight of ash-free and anhydrous substance present in cow dung, receive 34 parts by weight of ashless and anhydrous coal, from which 11 parts by weight of resin are extracted by extraction. manure per 100 weight, h. ashless and anhydrous 1st substance present in cow manure, receive 4 weight.h. resin. This suggests that the proposed method increases the yield of resin in the dehydration of cow manure. The calorific value of the extracted cow manure calculated on the basis of a material that does not contain water and ash is 14.0 MJ / kg. Example 3. 2500 g of Australian brown coal used in Example 1, containing 1500 g of water, 975 g of organic matter and 25 g of ash, are treated as an aqueous mixture after acidifying it to a pH of 3.5 with pre-treatment at. The pretreatment is carried out in an autoclave at a pressure exceeding the pressure of water vapor at, and then-i but at a pressure of 45 bar. After water separation, 13 pO g of a partially carbonated product containing 300 g of water, 975 g of organic matter and 25 g of ash are obtained. This product is subjected to further treatment at atmospheric pressures at 37 ° C, at which heating is carried out directly with superheated water. ferry. 645 g of anhydrous coal are obtained, the calorific value of which is 29.3 LJ / kg, containing 25 g of ash and 140 g of resin. Resin entrained in water vapor is recovered from it by condensation. The resin yield is 5.60 parts by weight. from the initial amount of brown coal. Example4. 1000 g of Australian brown coal used in Example 1, containing 600 g of water, 390 g of organic matter and 10 g of ash, is subjected to a pre-treatment in the aqueous mixture after acidifying it to pH 3.0 by heating to 250 ° C with a heating rate of 10 ° With in a minute. The pretreatment is carried out in an autoclave at a pressure that exceeds the pressure of the water passes at, that is, at; 40 bar, and continue the treatment for 30 minutes. After separating the liquid water, 520 g of a partially carbonated product containing 120 g of water, 390 g of organic matter and 10 g of ash are obtained. At 50 bar, this product is heated to 340 ° C with superheated steam at a heating rate of 8 ° C per minute, followed by cooling immediately after reaching a temperature of 340 ° C. 258 g of anhydrous coal having a calorific value of 32.1 MJ / is obtained. kg containing 10 g of ash and 56 g of tar. Without isolating the resin, the product is briquetted to produce briquettes with a diameter of 11.5 mm. The grinding force of the obtained briquettes is 29.9 N. For comparison, the two-step process is repeated under similar conditions, except for the introduction of acid in this case, the pH of the mixture is 8. The grinding force obtained from the coal briquettes is 6.1 N.

The briquettes amount to 31.8T1 when briquetting the first product

MJ / kg. Stage of two-stage thermal

Lree briquetting of Australian-worth briquettes is 6.0 and

6yjporo coal, not subjected to 7.5 tl, respectively, from coal, to heat treatment, is obtained with briquettes worked in the presence and absence of a grinding force of 4.0 N, acid.

processing grinding force semi

Claims (4)

1. METHOD FOR DEHYDRATING LOW-VARIED SOLID FUEL, comprising heating a mixture of fuel and water to 300-374 ° C, characterized in that, in order to increase the calorific value of the fuel by increasing the resin content in it, heating is carried out in the presence of organic acid. 2. The method of pop. 1, characterized in that the organic acid is introduced in an amount necessary to achieve a pH of the mixture in the range from 3.5 to 6. 3. The method according to PP. 1 and 2, which consists in that the heating is carried out at a pressure below 85 atm 4. The method according to PP. 1-3, characterized in that before heating to 374 ° C, the mixture of fuel, water and organic acid is heated at 240-250 ° C and under a pressure that is higher than the pressure of water vapor at the heating temperature, and the fuel is separated from water. SU <„, 1056908 with a win 6.