DE1471570C3 - Process for the production of coke and volatiles from bituminous coal, subbituminous coal or lignite - Google Patents

Description

The invention relates to a process for the production of coke and volatile substances from bituminous coal, subbituminous coal, or lignite, comprises in the coal or lignite in broken form with a high-boiling aromatic liquid above 343 ⁰ C boiling point components at a temperature above 300 ° C and normal or elevated pressure to form a solution of the soluble carbon-like components in the aromatic liquid with insoluble solid residues suspended therein, the suspended solid particles are separated from the solution and the solution is then heated to a temperature above its incipient coking temperature and with the formation of vapors and coke is coked.

Such a method is known (U.S. Patent 3109803). This known method, in which high-boiling aromatic liquids with initial boiling points of 343 to 454 ° C. and in particular about 399 ° C. are used to digest the crushed coal, is just like another similar known method (British patent specification 457 971) in which to digest the pulverized coal high-boiling residue fractions are used, which are obtained when fractionating the volatile products resulting from the coking, insofar as only part of the soluble carbonaceous components of the feedstock actually goes into solution during the digestion and also the thermal stability of the Digestion leaves something to be desired, so that these solvents cannot be continuously circulated without deterioration and with practically no loss. The disadvantage that the solvents used, namely high-boiling coal tar oils, in particular anthracene oil (German patent specification 320 056), or coal tar, water gas tar and tar oils (British patent specification 387 658), do not completely dissolve the components of the feedstock which are soluble in high-boiling aromatic oils, also adheres to these other known processes in which pulverized coal is digested by heating with the solvents mentioned in order to obtain pitch-like or bituminous masses that can be used for various purposes. or to improve their coking properties.
The invention is therefore based on the object of improving the above-described method known from US Pat. No. 3,109,803 so that when the crushed coal is broken down, the soluble, carbon-containing constituents are higher

ίο Percentage and, if possible, even practically quantitative go into solution, with the coking no adverse change in the solvent occurs, the solvent is completely stable at high coking temperatures, both from the coal extract and from the liquid products cracked in the coke can be completely separated and that no polymerization or condensation of solvent components takes place, making this practical can be recovered quantitatively, and that the solvent with constant circulation in the Process itself not in terms of its extraction efficiency and its temperature resistance getting worse and better.

It has now been found that this object can be achieved by opening the crushed Coal is a high-boiling aromatic solvent instead of the solvent previously used for this purpose Liquid with a boiling range within the intersection points, converted to 1 atmosphere, used from 316 to 482 ° C.

The invention thus relates to a method of the type specified at the outset, which is characterized is that for the digestion a high-boiling aromatic liquid with a boiling range within the intersection points, converted to 1 atmosphere, from 316 to 482 ° C is used by the fractionated The vapors released during the subsequent coking process are recovered by distillation will.

The high-boiling solvents used according to the invention for digesting the coal contain predominantly angular-polycyclic-condensed polynuclear aromatics.
It is known that the effective coal solvents are those which have an angular arrangement of the rings, e.g. B. Phenanthrene, and boil above 300 ° C. Non-angular or linear condensed ring systems, e.g. B. anthracene, on the other hand, have a much lower selective solvent effect with regard to the coal components, which act as binders for the micelle fraction of the coal and, through their removal, a complete disintegration of the colloidal structure of the coal and a peptization of the micelles in the 'solvent can be achieved.

Phenanthrene (boiling point 340 ° C) has an angular structure compared to the carbon-containing one Coal materials have an extraction efficiency of 95% of the ashless coal, while the Anthracene having a linear structure gives only a yield of approximately 24% on the same basis.

The raw tar fractions from coal coking,

z. B. Anthracene Oil, contain significant amounts of anthracene and phenanthrene and are different for each Uses good solvents. Anthracene oil, which is used in some of the known processes discussed at the beginning used as a solvent normally boils between 271 and 399 ° C. When trying

With a solvent that had intersections, converted to an atmosphere, from 316 to 482 ⁰ C and came from a coal tar pitch, it was now surprisingly found that higher-boiling alkylated homologs of phenanthrene and other similar high-boiling polycyclic condensed aromatic ring compounds with Angular structure causes a better solution and such tar oil fractions are superior to all solvents known for this purpose in terms of the dissolving effect, despite apparently only insignificant differences in the composition. ■ ·

Another important advantage of the solvents used according to the invention is that the extraction efficiency increases even further through repeated use, since the heat resistance of the solution is improved with each pass through the process The reason for the increase in the extraction efficiency is presumably the increase in the thermal stability of the solvent as a result of a reduction in the undesired content of anthracene and its higher-boiling linear homologues, which ultimately results in a stable, completely recoverable solvent of the highest solvency results, which is then completely recovered from its solution without losses through polymerization of the heavy components at temperatures of 416 ° C. and above can be. It is even so heat resistant that it either from the deashed coal solution or from the _(more cleaved liquid product at temperatures of ^482; C and above, is recovered by delayed coking operations practically quantitative.

Instead of the solvent preferably used, derived from coal tar pitch, in the process the invention also -other heat-resistant polycyclic aromatic solvents are used, obtained by catalytic and thermal cleavage of mineral oil and within the range according to the invention the prescribed intersections boil. The solvency of such a solvent is carried out in an analogous manner by improving the heat resistance with each pass the process bigger until a fully recoverable one Solvent of highest solvency is obtained.

In the method of the invention, the raw coal used is from the series of bituminous coal, subbituminous Coal and / or lignite, as already mentioned, initially in a crushing and grinding device broken and ground. The particle size distribution can range up to 10 mm. Preferably will However, the raw coal is ground so finely that the main part of the coal particles clear a sieve with a Mesh size of 0.149 mm (No. 100) happened.

The invention is explained in more detail below with reference to the drawing, the single figure of which is a schematic flow diagram of a preferred embodiment reproduces.

According to a preferred embodiment of the invention, ground or pulverized coal is obtained from a hopper 1 into a conveyor 2, through which it is continuously at a set speed a solution device 3 is supplied, which is under a pressure of 1 to 10 atmospheres. In the system shown in the drawing, a screw conveyor is provided as conveyor device2, which feeds the coal into the solution device 3 in such a way that no pressure loss occurs in this, but could any other mechanical conveyor can be used instead, with which the Coal are transferred to the solution device 3

ίο can without a noticeable loss of pressure in this entry. .

^{High-boiling liquid solvent with intersections of 316 to 482 C} is fed into the dissolver 3 via a line 4 at a rate at which the ratio of solvent to coal is from * />: 1 to 6: 1. Usually a solvent to carbon ratio of 1: 1 to 3: 1 is preferred because good extraction rates are achieved in this range while reducing filtration costs. The dissolving device 3 is kept at a temperature of 316 to 454 ° C., preferably at a temperature of 399 ^V C, and at a pressure of preferably 1 to 5 atmospheres. Under these conditions, essentially all of the extractable carbon-containing substances contained in the raw coal are thermally depolymerized. The depolymerization products are soluble in the solvent and form a homogeneous carbon solution with the solvent. Insoluble solids containing mineral substances or ash and fiber charcoal or fusain are suspended in the cooling solution. In order to stir the mixture of coal and solvent during the dissolution process, a stirrer (not shown in the drawing) can be provided.

The solution temperatures in the solution facility 3 are expediently kept at the desired level in that one part of the coal solution and / or withdrawing coal-solvent mixture and circulating through an external heating system leaves. For this purpose, a part of the contents of the solution device regulated by a valve 7 is withdrawn with the aid of a pump 6 a line 5 is conveyed to a heater 8 and then via a line 9 into the solution device 3 returned. In this way one needs to maintain the solution temperatures in the solution device 3 to get no high pressure heating system that would be necessary if the solvent were on one Sufficient temperature to maintain the solution temperatures in the dissolver would be preheated.

A residence time of the raw coal in the solution. Setup of around 3 to 120 minutes is usually sufficient in order to dissolve the extractable, carbonaceous substances effectively and economically. Because the solvent has an initial intersection (converted to one atmosphere) of 316 "C, while the solution temperatures around 454" 'C The solution device 3 is provided with a vent line 10 regulated by a valve 11 provided that the withdrawal of low-boiling components of the solvent and evaporated from the raw coal volatile substances allowed. It has been found, however, that the amount of volatiles is practically negligible is. A removal line 12 arranged on the floor results in a substantially homogeneous Charcoal solution peeled off in the undissolved and

5 6

insoluble solid parts are suspended, the mineral coal solution via a line 22a into the coking

Fiber coal or Fusain and minerals or ash drum 23 passed in which they formed coke

contain. This suspension is coked with a pump 14 and a vapor phase. At the introductory

Via a cooler 13 a continuously working tion of the solvent in the coking drum

Rotary filter 15 is supplied, in this way 5 can be some foam. This can be effective

over 95 ° / ₀ on the ash-free coal. based are prevented from being at the feed point

extractable carbonaceous substances have been obtained. or at a slightly higher point of the

The coal solution is a small amount of anti-coke as it passes through the cooling system.

Lers 13 cooled to 204 to 371 ° C. The rotary foaming agent is added.

filter 15 is preferably provided with a filter medium. The vapor phase is stratified from the coking stream and is normally operated at a pressure of mel 23 at the top through a line 25a taken from 2.81 to 4.22 atmospheres, around the in the coal solution and via a In line 25, virtually all of the suspended solids are fed into a fractionating column 27. While the coking drum 23 with distant. The filter cake is fed through a line 16 of the coal solution and is thereby discharged from the rotary filter 15 and gradually fills with coke from the coking recovery of the solution contained therein. drum 24 coke discharged as a product that is washed and dried over by means. The application of lines 26a and 26 to further treatment of filter aid is carried out on the filter prior to its operation. During normal operation, the cooling would improve the separation of insoluble and undissolved particles from the coal solution and draining of the coking drum 24 was completed. 20 before the coking drum 23 has been filled with coke when using pre-coated filters. As soon as the coke is obtained from the coking stream filtered coal solutions, the analytical mel 24 of which is discharged and the coking drum 23 is filled with coke to a predetermined level, regardless of the grayling, the content of the raw coal, which varies between 1 to 20%, is the coal solution via a line 22b to the verate - only between 0.02 to 0.08 percent by weight 25 coking drum 24, from which was formed. It follows from this that the effectiveness of the vapor phase is reduced by a line 25b, ash removal during the filtration is more of a function and, via line 25, the fractionation column 27 is supplied with the particle size of the ash particles than of the ash. After cooling down the salary is. When using filter aids with a coking drum 23, the coke for the high carbon content can be removed from the filter cake for further treatment through a line 26b and the charging of a combustion device. The lower limit of the det will be order. to use its heat content or calorific value above the initial coking temperature. The temperature range to which the coal

The sulfur content of coal with low sulfur solu- tion depends on the desired maximum

fel content (e.g. 1.46 percent by weight sulfur) is the volatile content of the coke produced,

to 0.3 to 0.6%, ie by an average of 70%, which is normally 1-2 to 16%. The upper

wrestles. Since the organic limit of this temperature range contained in the raw coal is determined by the

Sulfur is partially soluble in the solvent, minimum volatile content in the coke produced

the amount of sulfur separated from the raw coal is determined, which should normally be 6 to 8%,

a function of the pyrite and 40 da coke content of the coal with less than 6% volatile matter

Sulphate sulfur, since this is essentially completely hard and accordingly difficult to get out of the

is removed by filtration and thus the final. Can remove the coking drum,

valid sulfur content of the filtered carbon solution in The carbon solution can also be used in a contact

mainly a function of the original coking unit (this consists of a reactor

Organic sulfur content of the coal. At 45 with a downflowing bed of particulate

Highly sulphurous coal (4.3 percent by weight like material on which the coal solution is distributed and -

Sulfur) is the ratio of inorganic sulfate - it is coked) and then also at higher levels

and pyrite sulfur are coked to organic sulfur at normal temperatures, whereby a coke

wise larger than low-sulfur coals that contain less than 6% volatiles,

salary. Correspondingly, with strong sulfur 50 higher than for the formation of a coke with a

containing coal leads to a greater percentage reduction, minimum content of 6% volatile substances

of the sulfur content determined because the sulfur content temperatures are permissible because at

the filtered coal solution to 0.6 percent by weight of this mode of operation of the coke even then without difficulty

has been reduced, which means an overall reduction in abilities can be carried out if it is less

Sulfur content around 70 to 90%. 55 contains more than 6% volatile substances. Also requires

The practically completely deashed coal solution, the coking in the contact process no preheating, is fed via a line 17 into a pressure drum 18 of the feed material of the coking device, from which it is fed to a heater 21 via a line 19 and (coal solution) at temperatures above the initial pump 20 . In loan coking, since the Beschickungsder coil of the heater 21, the coal is heated 60 material in the coker by the sentient solution to 454-566 ⁰ C and then line coking 22 is fed to a coker unit via a bare heat of the contact materials in. Of the The device is heated to a temperature which is kept under a pressure of 1 to 6 atmospheres above the temperature at which the coking occurs. The illustrated coking unit 21 is an insert.

Coking device for the so-called delayed 65 The fractionation column 27 into which the vapor phase

Coking with two alternately charged coking from the coking device through line 25

coking drums 23 and 24. During a plant feed is carried out with suitable fractionation trays

phase, the heated (not shown) located in a line 22 is equipped. In the lower part of the

Fractionation column 27 are through the vent line 10 also those mentioned above, during of the dissolving process in the dissolving device 3 forming or withdrawn from it volatile substances fed in.

At the top of the fractionation column 27, a fraction is withdrawn through a line 28 which contains condensable and non-condensable components and is fed to a conventional treatment unit in which the condensable components are separated from the non-condensable components. At an intermediate point in the fractionation column 27, a medium-weight medium oil is drawn off by means of a pump 30 through a line 29 and passed through a line 31 to a cleaning unit (not shown). A portion of the medium oil in line 29, which is regulated by a valve 32, is passed through a line 33, a waste heat boiler 34 and a line 35, from which it is then divided into at least two substreams, through lines 35a and 35b as a return into the fractionation column 27 is returned.

A heavy medium oil is drawn off from the fractionation column 27 through a line 36 and passed into a pressure tank 37. By appropriate control of the temperature in the fractionation column 27 and in this by the lines 35 a and 35 /) fed retrace has the removed through line 36 middle oil intersections 316-482 ^C C, converted to an atmosphere, and thus provides the solvent which is used to dissolve the pulverized raw coal used in the dissolver 3. The dissolving device 3 can be regarded as being assigned to the fractionating column 27, but it is not necessary to operate the fractionating column 27 and the dissolving device 3 at the same pressure. In general, the total pressure in the solution device 3 will be somewhat higher than in the fractionation column 27 because of the usual rise in the temperature in the solution device above the temperature prevailing at the bottom of the fractionation device 27 and because of the presence of some lower-boiling coal fission products formed in the solution device 3. In the fractionation column 27, for example, pressures of 1 to 5 atmospheres are used, whereas in the solution device 3, pressures of 1 to 10 atmospheres are used, the valve 11 provided in the vent line 10 enabling the fractionation column 27 and the solution device 3 operate at different pressures.

The need for solvents may make it necessary

. that both the fractionation column 27 and the dissolving device 3 operated under higher pressure are to be removed from the fractionating column 27 by Ge-.winnung larger amounts of lighter portions that during Driving the fractionation column at lower pressures to side streams and / or overhead products are lost were going to get more solvent. Bottom products are removed from the fractionation facility 27 withdrawn through a line 38. You can be promoted by a pump 39 to the heater 21 and heated in this together with the deashed coal solution from line 19 and then coked will. A portion of the bottom product withdrawn through line 38 regulated by a valve 41 can be branched off by a line 40 and sent to storage and cleaning devices (not shown)

leads to be. . .

Particularly necessary when starting up the system fresh solvent can be introduced into the process cycle from outside by adding it feeds into the pressure tank 37 via a line 42 in amounts regulated by a valve 43. From the Pressure tank 37 is the amount necessary for a solvent-carbon ratio of V2: 1 to 6: 1 Solvent withdrawn through a line 44 with a pump 45 and through a valve 16 that the Controls the amount of solvent, conveyed to line 4 and through this into the solution device 3. When after the start of the process, the amount of available solvent exceeds the requirement required for the dissolution process Excess solvent in controlled amounts by a valve 48 via a line 47 from the Pressure tank 37 can be withdrawn.

The following examples and comparative experiments illustrate the invention.

-. ' . ■. ■ · ■ ■ ■.

Examples ibis 3 and comparative experiments I and U.

3 examples and 2 comparative experiments were carried out with different raw coals. The used Starting materials and solvents, the process conditions used and those achieved Results can be seen from Table 1 below.

Table I.

Example or
Comparative experiment no.

(Comparison) (invention)

Pana

deashes

(Invention)
money

Illinois

II

(Comparison)

Sea coal

(Invention)

Sea coal

Coal analysis values in
Weight percent about

Humidity ............

volatile substances ... ·. ·; .....

solid carbon .......

Ashes .. '.

sulfur

Chlorine.;

2.69 37.7: 38.9 19.66

3.72 moisture-free Base

33.6
56.6

9.8

4.0.

0.15

32.6

67.1

0.3

1.9

0.003

2.75

38.90

53.99

7.11

. 1.18

1.4

36.6

56.6

5.4

1.46

1.4

36.6.

56.6

. 5.4

1.46

309 649/132

Table I (continued)

Example or
Comparative experiment no. 2
(Invention) Pa
raw ' n / A
deashes Illinois II
(Comparison) , 3
(Invention) .1.
(Invention) money Sea coal Sea coal I.
(Comparison)

solvent
Boiling range ⁰ C:

Start of boiling

End of boiling

made heat resistant

Solvent-to-carbon ratio ....

Solution temperature, ⁰ C

Solution pressure, atü

Dwell time, min.

Filtration ^{temperature, 0} C .......

Yield of ash removed coal,
related to

a) broken coal

b) ashless coal

specific gravity 38/38 ° C

Softening point ⁰ C (ball-ring) sulfur, percent by weight .......

Coking residue, percent by weight:

a) Ramsbottom

b) Conradson

CSo solubility in percent by weight

Bitumen .. '

■ ashes ■ ·. .'... ■

difference

399> 566 no 3 to 1

427-

5.27 20 288

67.3 83.8

1.2516 64.0

0.63

32.7

76.81

0.06

23.13 316

482

Yes

3 to 1 427

5.27 20
329

83.6 92.7

1.2250 55.0

76.56 0.08 21.36

316 399 316 482 > 566 482 Yes no. Yes 2 to 1 2 to 1 3 to 1 418 427 " 427 5.27 5.27 5.27 3 20th 20th 316 232 316 85.3 67.5 90.0 91.8 71.3 95.2 __ 1.2523 1.21.40 .100.0 - - 0.44 0.51

35.9

68.35

0.07

31.58

23.9

81.01

0.05

18.93

In the experiments shown in Table I it was found that the yield of deashed coal or the percentage of the soluble fractions of the raw coal actually going into solution in the solvent in comparative experiments I and II, for which a solvent was used that did not meet the intersection points according to the invention had to be used solvent, but a boiling behavior, as it should have according to the US Pat ⁰ C was used.

The following Table II gives those relating to organic Sulfur, pyrite sulfur, sulphate sulfur and total sulfur. obtained in Example 2 of Table I. Desulfurization again.

More organic

Pyrite-S,%.
Sulphate-S, ° / o

Coal extract

Total S, ° / ₀ . | 1.181

0.593 points from 316 to 482 ⁰ C again, which was used in Examples 1, 2 and 3 of Table I.

0.593

no determinable amounts no determinable amounts

Table III gives analytical characteristics of a typical high-boiling solvent with a table of cuts III coal solvent, boiling behavior

Percent distilled Steam temperature ⁼ C
converted to
760 mm high abs. Start of boiling 221
302
316 5 346
363
372 10 ..... 381
391
403
416
445 20th 472 30th 488 40 98.0
2.0
none
1.1664 50 60 70 80 90 95 End of boiling ....... V Percent by weight distilled
Weight percent residue ...
Weight percent losses
(by forming the difference)
Specific weight (38 / 15.6 ° C)

The expression that the solvent has "intersections of ..." means in the description and claim a solvent that contains components that are between the. specified Boiling points of intersection, with only a small part 5 of lower and higher boiling components, their The amount depends on the selectivity of the fractionation column used.

Table IV gives the coking according to the invention of a deashed coal solution (Example 2) achieved results again.

sample

12th

Table IV

Humidity ......

volatile substances .. solid carbon

ash

sulfur

chlorine

Origin of the coal: Illinois

Coal raw coal extract coke

2.75

38.9

53.99

7.11

1.18

20.0

77.9 0.56 0.593

90.22

1 sheet of drawings

Claims (1)

Claim: Process for the production of. Coke and volatile matter from bituminous coal, subbituminous coal or lignite, in which coal or lignite in broken form with a high-boiling aromatic liquid that contains components boiling above 343 ° C, at a temperature above 300 ° C and normal or elevated pressure to one Solution of the soluble carbon-like components in the aromatic liquid with insoluble solid residues suspended therein is digested, the suspended solid particles are separated from the solution and the solution is then heated to a temperature above its incipient coking temperature and coked with the formation of vapors and coke, characterized that a high-boiling aromatic liquid having a boiling range within the intersection points, is converted, used at 1 atmosphere of 316 bis 482 ⁰ C is recovered by fractional distillation the released beini the subsequent coking vapors for digestion. .