DE2504277A1 - METHOD FOR EXTRACTION OF COAL - Google Patents

Description

The invention relates to a special method for extraction of coal with a hydrocarbon mixture under hydrogenating conditions. The aim is largely to extract it ash-free and low-sulfur, soluble carbon materials.

There are "already numerous processes for the extraction of coal has been proposed. Many of them have, regardless of the type of solvent used, such as from low molecular weight polycyclic aromatics a considerable Hydrogen consumption, whereby the corresponding processes are unsatisfactory from an economic point of view.

Hydroaromatic compounds such as tetrahydronaphthalene, Decahydronaphthalene or hydrophenanthrene are used as solvents. These are transferred during the extraction process part of their hydrogen on the highly condensed structural units of the coal, whereby these partially can depolymerize and then go into solution. After separating the coal extract from the solvent by distillation the latter is re-hydrogenated in an additional process, step v, in order to be returned to the process.

As solvents, which also contain available hydrogen, Hydrocarbon cuts occurring in petrochemical plants, such as cracking oils, are also proposed

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250A277

with low aromatic content or medium oils with high aliphatic content. After they have been separated off, these too have to be hydrogenated before being returned to the extraction. Such procedures are complex and expensive in terms of equipment and process management.

In other processes, hydrogenation catalysts are added to the extraction feed. Your separation and recovery is often so expensive that it is left in the residual coal. This results in a significant decrease in value of these residues, the incineration of which can also be highly polluting without special equipment can.

The present invention is based on the object of finding a solvent which is technologically as simple as possible economic design of the process a) to extract a large proportion of the coal with low hydrogen consumption and b) can be recovered to a high degree in order to be fed back into the process.

From requirement a) it follows that the solvent components have a chemical structure similar to that of the coal itself should contain. Only then can fragments be found during the depolymerization of the coal that occurs during the extraction be brought into solution with high molecular weight. The resulting low degree of depolymerization of the coal causes at the same time low hydrogen consumption. This is fulfilled by systems with a high content of highly condensed Aromatics.

Requirement b) results in a solvent that can be easily distilled because it can have a high recovery rate can only be achieved economically by distillation.

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Because of the high boiling point of highly concentrated aromatic compounds, the two requirements are opposed to one another. The aim of the invention is to find an optimal compromise between them.

It has now been found that one can fulfill the above requirements, when the process for producing low-ash coal by-products by extraction of finely ground coal with a liquid hydrocarbon mixture as an extraction agent in the presence of hydrogen at 200-500 ⁰ C, preferably 375-425 ⁰ C. and a pressure of 10-750 bar, preferably 90-130 bar, and separating into non-extractable residue and extract and subsequent distillative separation of the extract, thus resulting in that as liquid hydrocarbon mixture is one having a boiling range of 135-550 ⁰ C. , preferably 180-290 ⁰ C, used at normal pressure, which by primary use of a heavy oil with a boiling range at normal pressure of ^{135-550 0} C, preferably ^{210-460 0} C, with a predominant aromatic content, preferably over 80 wt .- #, as Extraction agent arises during the extraction process itself. Coal and extractant are used in a weight ratio of 1: 0.5 τ 5, preferably 1: 1.5-2.5. During the extraction, the residence times can be in the range from 0.5-5 hours, preferably 1-3 hours.

Hard coals are suitable for carrying out the process with a high proportion of volatile components, i.e. flame coal, gas flame coal and gas coal, especially gas flame coal. The proportion of volatile constituents should be in the range of 28 - 45 #, preferably 30 - 40 #, (based on water- and ash-free coal). The particle size of the coal to be extracted should <2 mm. However, in principle, the extraction of larger particles is also possible, however, the degree of extraction then falls with the same residence time in the extraction vessel.

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Maximum extraction yields can be achieved by setting achieve the maximum extraction temperature typical for each starting coal used. This temperature is through Determine preliminary tests.

The object described is achieved according to the invention by that a heavy oil rich in aromatic compounds of the specified characteristics, preferably a pyrolysis heavy oil, d. H. the atmospheric residue of the liquid phase of pyrolysis, is used in the process, which bich under the conditions The hydrogenative extraction surprisingly converts it into a solvent that under low hydrogen consumption High molecular weight depolymers formed from the coal without the addition of catalysts dissolves and after the extraction can be recovered with high yield by distillation and fed back into the process cycle. at With a suitable choice of extraction conditions, the solvent is already formed in the first pass with a high yield. Losses as extraction agent through polymerization or polyaddition can by using the aromatic-rich heavy oil originally used when starting up the plant with the specified characteristics are replaced.

The advantages achieved with the invention are in particular that compared to other methods for obtaining ash-free and low-sulfur carbons due to hydrogenating Extraction, the hydrogen consumption is reduced, the scope of the system because the solvent hydrogenation is not required downsized and one of degrading catalyst residues free residual coal is obtained. In addition, the raw digestion obtained is thin and easy to filter, which means the usually costly separation of filtrate and residual coal is cheaper.

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The method described above can be used both batchwise and continuously using the methods for such technical task usual and. known technological methods.

The residue obtained after the distillative separation of the extract is then the low-ash coal by material which has a softening point or range in the range of 190 - 240 ⁰ C possesses. It is to be regarded as a slightly anhydrous carbon depolymer. It is also soluble in various masses in a number of common solvents and can be further separated in this way.

The low-ash, soluble ones produced according to the invention Carbon materials can be used as environmentally friendly heating means because of their low sulfur content. You can also serve as raw materials for the production of petrochemicals. They are also suitable as starting material for the Coking on electrode coke or for the production of soot. In finely powdered form, the carbon materials are on top. Can also be used as fuel for pulverized coal engines.

The object of the invention is achieved by the following exemplary embodiments explained:

Examples 1-6:

In an electrically heatable 5 1 stirred autoclave, 750 g of finely ground glass flame charcoal (particle size = 200 ^ un) and 1500 g of pyrolysis heavy oil and injected hydrogen with an initial pressure of 50 bar. The approach was heated to the specified final temperature, the pressure increasing. After an extraction time of total The autoclave was cooled for two hours and

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clock relaxed. The raw digestion was separated into the residual charcoal and the extract by filtration. From the extract were made by distillation of the carbon and the solvent recovered that was fed back into the process. Some typical test results are summarized in Table 1. They mean: waf = free of water and ash. The extracted portion of the used Understood coal.

From Table 1 it can also be seen that due to the major structural changes that the Under the extraction conditions, pyrolysis heavy oil has undergone a highly recoverable hydrocarbon mixture of considerable solvent power has arisen, which a considerable proportion of the coal with less Able to extract hydrogen consumption. Characteristic Specifications of the pyrolysis heavy oil used in the examples, the recycled solvent and the shows the coal used, and the obtained carbon material the table 2.

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Table Ii test conditions etc.

at
game solvent tempera
door
( ⁰ C) pressure
(bar) Extraction
degree in waf
(Si) solvent
recovery
W) H ₂ consumption / kg input
money
(Nl) 1 Pyrolysis
Heavy fuel oil 400 108 72.3 66.8 108 2 returned
solvent 375 106 43.2 95.4 50 3 Il 400 108 60.4 98.5 64 4th Il 400 109 61.3 95.6 74 5 Il 425 105 61.7 92.3 140 6th It 450 144 25.0 89.2 145

CJl CD

Table 2; Characteristics of the input materials and the end product

CD CJ CO

Pyrolysis
Heavy fuel oil • returned
solvent Ash content
(Wt .- ^) Feed coal Carbon Boiling range 214-458 180-290 Sulfur content
(Wt. - ¹ P) 7.2 0.2 Asphaltenes
(Wt .- ^) 13.7 C 0.05 carbon
(Wt, - ^) 1.41 0.3 Bromine number
(g Br / 100 g) 38.9 6.3 hydrogen
( Weight-fo ) 78 90 Softening
Point 4.8 5.9 approx. 120

Claims (4)

Patent claims above sea surface; "U_ process for producing low-ash coal by-products by extraction of finely ground coal with a liquid hydrocarbon mixture as the extraction agent in the presence of hydrogen" at 200-500 ⁰ C, preferably _t 375-425 ⁰ C and a pressure of 10 - 750 bar, preferably 90 - - 150 bar, and separating into non-extractable residue and extract and subsequent separation by distillation of the extract, characterized in that as the liquid hydrocarbon mixture is one having a boiling range of 135-550 ⁰ C, preferably 180-290 ⁰ C, used at atmospheric pressure, we3 .ches by primary use of a heavy oil with a boiling range at atmospheric pressure of 135 - 460 ⁰ C is produced, with a predominant aromatic content, preferably about 80 parts by weight S ^, as the extraction agent in the extraction process - 550 ⁰ C, preferably 210th 2. Process for the production of low-ash carbon materials according to claim 1, characterized in that coal and extractant in a weight ratio of 1: 0.5-5 , preferably 1 : 1.5-2.5, are used. , 3 .., Process for the production of low-ash carbon materials according to claims 1 and 2, characterized that retention times of 0.5-5 hours, preferably 1-3 hours, are observed during the extraction. 4. Process for the production of low-ash carbon materials according to one of claims 1-3, characterized in that the extraction is carried out continuously. dr.kn-ra 609 8 32/0504