JPS5945711B2 - coal liquefaction method - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a coal liquefaction process, and more particularly to an improved two-stage process for coal liquefaction.

Coal is liquefied in a single liquefaction stage consisting of a preheater coil that essentially completes the coal liquefaction, followed by a dissolver that further hydrogenates the liquefaction solvent and coal derived liquid.

Recently, a so-called two-stage liquefaction process has been proposed, in which the first stage is a short contact time thermal liquefaction, followed by recovery of an essentially ash-free liquid, which is further subjected to a second stage liquefaction. Quality is improving.

The present invention aims to improve such a two-stage liquefaction process.

The present invention solves the problem of obtaining all of the distillate product in an economically satisfactory manner, thereby eliminating the need for a second stage liquefaction zone to formulate the first stage liquefaction solvent. The aim is to significantly reduce the amount of product and increase the amount of distillate product.

The present invention provides an improved two-stage liquefaction process in which the liquefied solvent to the first stage contains an insoluble material containing 454°G+ (850°F+) liquid recovered from the first stage liquefaction. pumpable streams of ash, unmelted coal, etc.) and 454°C + (8
50°p+) Contains liquid.

The liquefied solvent to the first stage therefore contains heavy material (including insolubles) from the first stage and heavy material from the second stage.

More specifically, the first stage liquefaction is carried out at 443 to 468'C (8
30-875°F) outlet temperature, 126.6-189
．． 8 kg/ant gauge (1800~2700psi
g) Pressure on the order of 3 to 15 minutes [3
It is a short contact thermal liquefaction operating at temperatures above 16°C (600'F).

The coal liquefaction solvent used in the first stage is used in an amount such that the ratio of solvent to coal is on the order of 1.2:1 to 3:1 on a weight basis.

It should be understood that larger amounts can be used, but generally such large amounts are not economically viable.

Furthermore, hydrogen is generally 4000 to 1500 per ton of coal.
Add to the first stage in an amount of 0 SCF.

After processing to remove insoluble materials, the 454° C.+ (below 850+) liquid, essentially free of insoluble materials, is intensified in a second stage to further improve the quality of the material.

According to the present invention, 454°G+ (8
50'F+) liquid (generally at least 45% most commonly about 45-55%) flow at 454°G+ (850°F+
A pumpable stream of insoluble material (ash, undissolved coal, etc.) is used to formulate the liquefied solvent from the first stage.

According to the invention, the coal liquefaction solvent used in the first stage liquefaction zone of the process is between 15 and 50%, most commonly between 20 and 50%.
40% 454°G” (850°p+) liquid, 5-20
%, most commonly 5-10% of insoluble material;
the remainder is a 454°C (850°F) liquid with an initial boiling point of at least 260°C (500°F);
The 4°G (850°F) liquid is present in the solvent in an amount of at least 45%, most commonly at least 45%, and most commonly at least 50% (all percentages by weight).

Further, at least 10% and up to 40% of the liquefied solvent is derived from the pumpable stream of insoluble material recovered from the first stage demineralization and at least 25% of the liquefied solvent is derived from the second stage liquefaction zone.

The part derived from the second stage liquefaction zone is 454°C" (
below 850+) can be liquid alone, or 45
4°C+ (850'F+) and 454°C- (850'F+)
F-) Can be both a liquid and a liquid.

And in most cases, the liquid derived from the second stage liquefaction zone is primarily 454°C+ (850°F+ S liquid).

Therefore, the liquefied solvent consists of liquids boiling above 260°C (500°F), and the liquefied solvent is 454°C + (850°C) recovered from both the first and second stage liquefaction zones.
p + ) materials (the full range of materials derived from coal, excluding insolubles).

The coalification liquefaction solvent used in the first stage liquefaction zone is 15 to 5
The reason why 0% contains 454°G+ (850°p+) liquid is because if the above liquid exceeds 50%, the processing liquid taken out after coal liquefaction becomes viscous and cannot be pumped. .

Although it is a good solvent for coal, it is not preferable because it provides less hydrogen and less hydrogen is transported to the coal.

Also, less than 15% is undesirable because the LC fastener must be run at high conversion rates, which requires very rigorous handling and therefore requires high temperatures.

This also reduces the mobility of hydrogen into the coal.

The reason for limiting the amount of insoluble material to 5-20% is that if it exceeds 20%, the processing solution becomes unduly viscous, so the amount of inert material must be limited.

Also, the lower limit of 5% is inherent in the liquor coming from the demineralization zone, which typically contains such an amount.

The liquid at 454°C- (850'F-) is at least 45% as described above.
) as the remainder of the liquid and insoluble material.

Also, obtaining at least 10% of the first stage liquefied solvent in the pumpable stream is necessary since the first stage liquefied solvent does not have hydrogen for transport.

Finally, the limitation of at least 25% of the first stage liquefied solvent obtained from the second stage liquid effluent is due to the requirement for a flowable viscosity.

According to a preferred embodiment, the first stage effluent has a characteristic coefficient of at least 9.75, at least about 121°C (2
50°F), and at least about 1
Demineralize using a liquid accelerator having a 95% by volume distillation temperature below about 399°C (750°F) at 77°C (350°F).

As described in such patent specifications, the preferred accelerator liquids are 218°C (425'F) and 260°C, respectively.
It is a kerosene fraction with a 5% and 95% volumetric distillation temperature of 500°F.

The liquid essentially free of insoluble materials (less than 0.5% ash) recovered from deashing is then treated with an accelerator liquid (when such accelerator liquid is used for deashing) at a temperature below 454°C (850°F). Processed in a recovery zone to recover the boiling components, which are used to vortex to formulate the liquefied solvent, the high boiling point material i.e. 454°C1 (850'F+) is the feedstock to the second stage liquefaction. Use as.

A pumpable stream of insoluble material containing 454°C+ (8500F'') liquid is also recovered from deashing, a portion of which is used in formulating the solvent.

454°G” (850°p+) during the second stage liquefaction
The material is suitable for temperatures on the order of 399-454 °C (750-850 °F) and 140.6-211 k! 9/ff1(2
000-3000 psig) with the hydrogen and the second stage liquefied solvent, and the contact time is on the order of 1-5 hours.

In a second step, such contacting is carried out using a coal liquefaction catalyst of the type known to those skilled in the art, such as a cobalt-molybdenum or nickel-molybdenum catalyst supported on a suitable support such as alumina or silica-alumina. This is carried out in the presence of oxides or sulfides of Group and Group I metals.

According to a preferred embodiment, such second-stage liquefaction is accomplished in a countercurrent ebullient bed, such ebulent beds being known to those skilled in the art.

The effluent from the second stage liquefaction is then treated in a flashing step to remove the lighter components, i.e.
50°F) and the remaining product is liquefied solvent to the second stage, a portion of the liquefied solvent requirement for the first stage, and to obtain the net liquefied product. used for.

A specific example of the present invention shown in the accompanying drawings will be further described.

Referring to the drawing, pulverized coal in line 10, generally bituminous coal, subbituminous coal or lignite, preferably bituminous coal, hydrogen in line 11 and coal liquefaction solvent in line 12 (
(obtained as described below) is introduced into the first stage liquefaction zone 13 to perform short-time catalytic thermal liquefaction of coal.

Thermal liquefaction is carried out in the absence of a catalyst.

The first stage liquefaction is operated under the conditions described above.

The first stage coal liquefaction product is removed from zone 13 in line 14 and introduced into flash zone 15 from which approximately 26
Flushing materials that boil at temperatures from 0 to 316°G (500 to 6000F).

The thus flushed material is removed from flash zone 15 by line 16.

Flash zone 15 operates as a guard for flashing material boiling below the end point of the promoter liquid to be used in the subsequent demineralization step.

The remainder of the coal liquefaction product in line 17 is transferred to deashing zone 18
to separate ash and other insoluble materials from the first stage coal liquefaction product.

As specifically described, demineralization in zone 18 is accomplished using a promoter liquid to facilitate and enhance the separation of insoluble materials, such promoter liquid being supplied by line 19.

In particular, the separation in demineralization zone 18 is accomplished in one or more gravity settlers; promoter liquids and general methods for achieving such demineralization are described, for example, in U.S. Pat. No. 3,856,675. .

Essentially ash-free overflow is removed from deashing zone 18 by line 22 and introduced into recovery zone 23 .

The underflow containing insoluble material is removed from demineralization zone 18 by line 20 and introduced into flash zone 24 from which material boiling below 454 DEG C. (850 DEG F.) is flushed.

Flushing in zone 24 removes flowable insoluble material containing 454° C.+ (850'F") liquid from flash zone 24 via line 25.

The flushed components are removed from flash zone 24 by line 26 and introduced into recovery zone 23.

A portion of the 454°C+ (850°F+) material in line 31 is introduced into first stage solvent storage zone 32 and is used to formulate the first stage liquefied solvent as described below.

The remainder of the material in line 33 may be used as feed to a partial oxidation step to produce hydrogen.

Recovery zone 23 includes one, two or more distillation columns which recover promoter liquid in line 41 and subsequently pass it into deashing zone 18 via line 19 and optionally via line 42. Operation designed to be introduced after replenishing the liquid.

Additionally, a temperature of about 316° C. (600°
A stream boiling in the range of about 482°C (9000F) is collected in line 43.

454°C + (850°p + ) material is recovered from recovery zone 23 by line 51 and transferred to second stage liquefaction zone 52
is introduced along with hydrogen in line 53 and second stage liquefaction solvent in line 54.

The second stage liquefaction zone 52 operates at temperatures and pressures as described above and preferably uses a coal liquefaction catalyst of the type described above.

According to a preferred embodiment, the second stage liquefaction is in the form of a countercurrent boiling bed.

The effluent from the second stage liquefaction in line 55 is introduced into flash zone 56 and from there about 454'C (850'C)
F) Flushing materials with boiling points below; such low boiling materials are recovered in line 57.

If desired, some of the material in line 57 is used in line 62 to formulate the liquefied solvent.

45 recovered from flash zone 56 by line 58
The 48C+ (850 below+) product is used by line 54 to provide the second stage liquefied solvent and by line 59 to formulate the first stage liquefied solvent.

The remaining portion is recovered as net product via line 61.

The first stage liquefied solvent in storage zone 32 is transferred to line 43 from 316 to 482°0. (600-900°F) containing insoluble materials in line 31;
The 4°C+ (850°F+) liquid and the 454°C1 (850°F+) material from the second stage liquefaction in line 59 are blended together.

If desired, some of the lighter material recovered from the second stage can be used in formulating the first stage solvent.

Although the invention has been described with respect to particular embodiments, it is to be understood that the invention is not limited to such examples.

For example, demineralization can be accomplished in ways other than those specifically shown here.

Similarly, the second stage liquefaction can also be achieved in ways other than those specifically indicated here, ie other than by using a countercurrent boiling bed.

The present invention utilizes coal-derived 454°C+ (850°F+)
) material to provide a portion of the liquefied solvent, such 454°C'' (850°p+) material being obtained from a pumpable stream of insolubles recovered from demineralization;
It is thus advantageous to reduce the amount of material from the second stage required to formulate the first stage liquefied solvent.

[Brief explanation of drawings]

FIG. 1 is a process diagram of an example of the present invention. 13 is the first stage liquefaction zone, 15 is the flash zone, 18
is a deashing zone, 23 is a recovery zone, 24 is a flash zone,
32 is a first stage solvent storage zone, 52 is a second stage liquefaction zone, and 56 is a flash zone.

Claims (1)

Claims: 1 Contacting coal, a first stage, a liquefied solvent, and hydrogen in a first stage thermal liquefaction zone to produce a first stage effluent; F+) recovering a pumpable stream of insoluble material containing a liquid and an essentially ash-free liquid; contacting the essentially ash-free liquid and hydrogen in a second stage liquefaction zone to form an essentially ash-free liquid; improve the quality of the free liquid and produce a second stage liquid effluent; from the second stage liquid effluent to 454°C
0° p + ) in a two-stage liquefaction process for coal by recovering liquid at 454 °C, in which the first stage liquefaction solvent for the first stage thermal liquefaction zone is recovered from the first stage effluent.
a portion of the pumpable stream of insoluble material containing "(850'l") liquid, and a portion of the liquid recovered from the second stage liquid effluent; 454℃ with 15-50% liquefaction solvent in the first stage
+ (850°F+) liquid, 5-20% insoluble material and at least 45% at least 260°C (500°
F) a liquid having an initial boiling point of A process characterized in that it is obtained from a distillate and/or a recovered product obtained by flashing a two-stage liquid effluent. 2 454°C+ with 45-55% pumpable flow
2. The method of claim 1, comprising (850<0>F + ) liquid and the remainder being insoluble material. 3 First stage liquefaction solvent at 454 °C + (20-40%
850°F+) liquid. 4. The method of claim 3, wherein the first stage liquefaction solvent contains 5-10% insoluble material. 5 454°C- with a first stage liquefaction solvent of at least 45%
5. The method of claim 4 comprising (850<0>F-) liquid. 6 At least 25% of the second stage liquid effluent is at 454°C
- (850-) liquid and 454°C + (850'F"
) a liquid. 7. The method of claim 2, wherein no more than 40% of the first stage liquefaction solvent is derived from a pumpable stream of said insoluble material. 8 First stage thermal liquefaction at 443-468℃ (830-87℃)
5°F) outlet temperature 126.6-189 kg/ffl
3. The method of claim 1, wherein the process is carried out under pressure of 1800 to 2700 psig and in the absence of a catalyst. 9. The method according to claim 8, wherein the second stage liquefaction is carried out in a countercurrent boiling bed.