WO1982002057A1 - Method for processing coal containing water,particularly lignite - Google Patents

Abstract

In this processing method by heating a mixture of raw coal and hydrocarbon oils, a mixture of finely divided raw coal, a hydrocarbon heavy oil and light hydrocarbons are heated at a temperature comprised between 50 and 300?oC during 0.1 to 30 minutes; the water and the light hydrocarbons separate simultaneously from the mixture. The light hydrocarbons may be added to the mixture in a closed circuit. There are eliminated from the process on the one hand the water and on the other hand the remaining mixture composed of coal and hydrocarbon heavy oils. By combining in a single phase the heating of the mixture and its separation into its components, the water content of the coal may be considerably reduced. Furthermore, it is easy to proceed in such a way that the mixture of coal and hydrocarbon oils may be conveyed by pumping.

Description

 Process for the treatment of water-rich coals, especially lignite

Application of the invention:

The invention relates to a method for the treatment of water-rich coals, in particular lignite, by heating a mixture of. Raw coal and hydrocarbons.

Certain coal texts, in particular brown coal, contain up to 70% by weight of water and are not suitable as raw coal for combustion, gasification or hydrogenating liquefaction. Such foals must be dewatered before processing, and in the case of hydrogenating liquefaction to a residual water content below 8% if possible. It has been shown that, for. B. Australian brown coal with higher water contents is difficult, sometimes not at all in sufficient quantities in heavy hydrocarbon oils to be brought into the hydrogenation reaction in a mixture with these. Lignite, sub-bituminous coal and corresponding materials are to be understood as lignite.

Characteristics of the known technical solutions: Since these coals can only be dewatered to a water content of about 10% by weight by heat treatment, which is very expensive in terms of equipment, attempts were made early on to dewater e.g. B. Lignite after Add hydrocarbon oils (DT-PS 1 048 378). The coal / oil mixture is heated to 250 - 380 ° C at about 30 bar and then the water is separated off in the form of steam. Part of the oil is separated from the mixture and used in the circuit for mixing with further coal, the remaining dewatered coal / oil mixture for further processing in the present case - brought to separation. The process is less complex than the usual heat treatment of coal, but the degree of dewatering is still unsatisfactory.

According to a modification of this method, not a heavy hydrocarbon oil, but a light, e.g. B. a gasoline added to the water-containing coal, which separated the coal mixture after the heat treatment in a conventional manner with removal of the water and used in the circuit again for mixing with other coal (DT-AS 25 26 933, see FIG. 2). However, this process is also unsatisfactory, since only water contents of the coal of about 8% can be achieved.

These previously described processes were then combined and, instead of a circulating heavy or light hydrocarbon oil, a mixture of both types of oil was proposed for the recirculation, the heating of the coal / oil mixture to about 100-300 ° C. and then the separation carried out in a separator should be (DT-0S 28 10 479). However, the combination of the processes described earlier did not lead to sufficient success, since the water content of the lignite treated could in turn only be reduced to about 10%. Purpose of the invention:

The invention has for its object to improve a method of the type described above, the lower water content of the coal can be achieved.

State of the Invention:

To achieve this object, the invention proposes that a mixture of finely ground raw coal, a heavy hydrocarbon oil and light hydrocarbons is heated to 50-300 ° C. with a residence time of 0.1-30 minutes, with water and light hydrocarbons being removed simultaneously the mixture is separated, the light hydrocarbons are recycled to form the mixture and the water and the remaining mixture of the coal and the heavy hydrocarbon oils are removed from the process.

By changing the way of working, which has always been described so far, to heat the coal / hydrocarbon mixture to the working temperature and then to separate it into the desired components without further heat addition or after cooling, it is possible to combine the inventive method of operation, heating and separation into one working step to achieve significantly lower water contents in the coal than was previously possible.

The raw coal can be ground to the fineness required for the hydrogenation before being mixed into the hydrocarbon oils, but advantageously also in a mixture with these. The mixture can be prepared in the usual way. The ratio of coal, calculated anhydrous, to the heavy hydrocarbon oil will generally be chosen between 1: 2 and 1: 0.7, preferably with the highest possible coal concentrations. A quantity of light hydrocarbons should be added to the mixture in such a way that it is sufficiently pumpable. The ratio of serious Light hydrocarbon oils can be selected between 1: 3 and 1: 0.25 depending on the use of the former oils. Heavy hydrocarbon oils used are generally heavy oil or residue fractions boiling above about 200 ° C. which originate from coal hydrogenation, but corresponding foreign oils can also be used.

As light hydrocarbons one selects below the start of boiling of the heavy oils mentioned boiling liquid hydrocarbon mixtures, e.g. B. gasoline fractions, or individual gasoline components, for. B. paraffins or aromatics of the corresponding boiling point. Has also been advantageous for. B. proven xylene.

The prepared mixture is then, optionally after preheating, introduced into an apparatus suitable for the heat treatment with simultaneous removal of water and light hydrocarbons, e.g. B. in a distillation column or a falling film evaporator. Depending on the light hydrocarbons chosen, the heat treatment is carried out at temperatures of about 50 to 300 ° C., optionally at elevated pressures of up to about 10 bar, for a period of 0.1 to 30 minutes. The water and hydrocarbon vapors obtained are condensed in a conventional manner and separated from one another. The hydrocarbons are returned to the raw coal mixer and the water is removed from the process. The coal / heavy oil mixture obtained from the treatment apparatus can be fed directly to the coal hydrogenation, which can be carried out in a known manner. The water contents in these mixtures are less than 8% by weight, based on the coal. In general, values of 5% and lower can be achieved. Design example:

In the drawing, an embodiment of the method according to the invention is shown in principle, with the reproduction of the auxiliary equipment being dispensed with.

Raw lignite is introduced via line 1, a high-boiling oil originating from the coal hydrogenation via line 2 and a light petrol likewise originating from the hydrogenation is introduced into the mixing apparatus 4 via line 3. The mixture passes through line 5 in a rotary drum 16, in which generally at a slightly elevated temperature, for. B. 50 - 80 ° C, a fine grinding takes place. The mixture is then introduced via line 7, the preheater 8 and line 9 into the heat treatment apparatus 10, which is shown here as a falling film evaporator. Here, with the supply of heat via line 11, the heat treatment takes place with sufficient duration, in the course of which the water and gasoline vapors formed are drawn off via line 13. The coal / oil mixture subsequently provided for hydrogenation with a water content of z. B. <1% dissipated. The water and gasoline vapors are condensed in the condenser 14, the liquids obtained are fed via line 15 into the phase separation 16 and there into a gasoline stream, which is returned via line 3 to the mixing apparatus 4, and into a water stream, which is discharged via line 17 the process is removed.

example

Finely ground Australian lignite with a water content of 55% by weight was dried in a conventional manner by heating to a water content of 10% by weight. The coal was then placed in a heavy oil in the ratio of coal: oil = 1: 1.5 and mixed. The mixture thus obtained, coal content 40%, was so highly viscous that it was not pumpable. A mixture of coal, heavy oil and xylene, ratio 1: 1: 1, was then produced from Australian brown coal and treated according to the invention at 150 ° C. for 20 minutes. The water content of the coal / heavy oil mixture intended for the hydrogenation, coal content 50% by weight, was less than 1% by weight, based on the coal. The mixture was pumping itself.

A mixture of Australian brown coal, heavy oil and xylene, ratio 1: 0.85: 1, as treated according to the invention as described above, also gave a still pumpable coal / heavy oil mixture. After the water had been separated off, the coal content was approximately 54% by weight and the water content was 3.5% by weight. Here the limit of pumpability was reached.

Claims

Patent at speech ======= ==== ======== == == ====== 1. A process for the treatment of water-rich coal, especially lignite, by heating a mixture of the raw coal and hydrocarbon oils, characterized in that a mixture of finely ground raw coal, a heavy hydrocarbon oil and light hydrocarbons with a residence time of 0.1-30 minutes heated to 50-300 ° C, at the same time separating water and light hydrocarbons from the mixture, recycling the light hydrocarbons to the mixture formation and removing the water and the remaining mixture from the coal and the heavy hydrocarbons from the process. 2. The method according to claim 1, characterized in that the raw coal mixture is subjected to fine grinding before heating to the treatment temperature. 3. The method according to claim 1 and 2, characterized in that one carries out the heat treatment tinter pressures of 0.1 - 10 bar. 4. The method according to claims 1 to 3, characterized in that one carries out the heat treatment in a falling film evaporator.