Title of Invention

AN IMPROVED METHOD OF LIQUEFACTION OF COAL AND REACTOR THEREFOR

Abstract There is proposed an improved method for the liquefaction of coal by solid phase hydrogenation using hydrogen gas, which comprises introducing the coal particles into a preheating zone provided with a pair of corrugated solid internal surfaces provided oppositely and in the close proximity of each other, held at a temperature of around 650° C from the top of the zone, introducing high pressure hydrogen gas at a pressure of 1000 -1800 psig and at a temperature of 600 - 650° C, at an angle of about 90 degree to the following coal particles below the point of introduction of coal, to impinge upon the stream of coal particles to hit a first internal surfaces of the pre-heating zone and there after hitting a second internal surface opposed to the second surface, then a fourth surface opposed to the third surface and so on until the pre-heated solid material reaches the lower end of the pre-heating zone, where after the pre-heated solid and the gas are maintained in contact with each other at a reduced gas pressure in a horizontal reaction zone for completion of the reaction, the said first, second, third, fourth and other surfaces being in staggered relationship and wherein the product coal is subjected to a instantaneous direct quenching step by the use of a cooling medium such as methanol and dry ice at a temperature near 0°C. A suitable reactor is also provided.
Full Text This Invention relates to an improved method for the liquefaction of coal by solid phase hydrogenation.
It is already known to subject coalparticles to liquefaction by pyrolysis.
In the known art. the hydrogenation has been carried out catalytically. The catalyst used is Molybdenum oxide.
In the known art process, the product obtained is either fuel oil or a mixture of BTX liquids and gas or synthetic natural gas, depending on the proper combination of time, temperature and hydrogen partial pressure. The advantage of such a process against liquid phase hydrogenation is that it takes very little time (of the order of seconds) to convert coal, when in direct contact with hydrogen. The mechanism by which coal is convened is as follows:
Coal -> Heat -> Free radicals
Free radicals -> H2 -> Heavy and light liquid
Heavy and light liquid -> H2 -> Gas
The catalyst is Na2Co3 which is a cracking catalyst. It has been used for gasification of coai in the prior art. Some other prior art has also used Molybdenum for both liquefaction and gasification, where it acts as a hydrogenation catalyst, instead of cracking catalyst.
It will be appreciated that Bituminous coal goes through a plastic regin when heated to 350° C. Thus, hydrogenation is not feasible in fluidized bed, the plastic coal being sticky causing agglomeration.
Thus, in the known art, fluidized bed Reactors, there is problem of efficient conversion of coal to desired products. The agglomeration of coal not only reduces the yield of the desired products but also causes operational problems due to sticky nature of the particles on the bed.
Other drawback is that unwanted gaseous products also result to substantial extent.
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Therefore, an object of the invention is to propose an improved method and a Reactor for the liquefaction of coal.
Another object is to propose such a method whereby agglomeration of coal particles is totally avoided.
It is a further object of this invention to propose an improved Rector where instantaneous heating of the coal particles to a desired temperature is possible.
It is still further object to totally dispense with fluidized bed conversion.
A further object of this invention to propose such a method whereby there is provided efficient exposure of the coal particle to the hot gas, namely hydrogen.
These and other objects will be more clear from the following paragraphs.
According to this invention, there is provided an improved method for the liquefaction of coal by solid phase hydrogenation using hydrogen gas, which comprises introducing the coal particles into a pre-heating zone provided with a pair of corrugated solid internal surfaces provided oppositely and in the close proximity of each other, held at a temperature of around 650° C from the top of the zone, introducing high pressure hydrogen gas at a pressure of 1000 - 1800 psig and at a temperature of 600 - 650° C, at an angle of about 90 degree to the following coal particles below the point of introduction of coal, to impinge upon the stream of coal particles to hit a first internal surfaces of the pre-heating zone and there after hitting a second internal surface opposed to the second surface, then a fourth surface opposed to the third surface and so on until the pre-heated solid material reaches the lower end of the pre-heating zone, where after the preheated solid and the gas are maintained in contact with each other at a reduced gas pressure in a horizontal reaction zone for completion of the reaction, the said first, second, third, fourth and other surfaces being in staggered relationship and wherein the product coal is subjected to a instantaneous direct quenching step by the use of a cooling medium such as methanol and dry ice at a temperature near 0°C.
There is also provided a reactor for liquefaction of coal by the solid phase hydrogenation method as herein described comprising a chamber having a pre-heating zone, followed by a reaction zone immediately after the said pre-heating zone characterized in that said pre-heating zone is made up of two verticle parallel corrugated surfaces, each corrugation being formed of projected solid unit running across a width of respective parallel surfaces, there being provided a plurality of such solid units in the vertical direction and each unit separated from the next unit by a suitable space and wherein the projections in the first parallel surface are symmetrical to the projections in
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the second parallel surface and are in staggered relationship with each other, an inlet at its top end for the admission of coal fortified with sodium carbonate, an inlet for the pressurized hydrogen gas also at the top end of the chamber at a level slightly below the inlet level for the coal, a plurality of solid inclined units disposed in the pre-heating zone, said plurality of units being opposed to each other in a pair of vertical rows in a parallel relationship and in a staggered fashion, each said unit having three surfaces in the pre-heating zone a) a first top surface b) a second front surface and c) a third bottom surface and wherein each said first top surface is inclined towards the interior of the pre-heating zone, a reaction zone immediately after the said pre-heating zone.
The first surface is an inclined towards the Centre of the pre-heating zone, and each said front surface is a vertical surface and each said third surface is preferably an inclined surface divergent towards the wall surface on which it is formed.
The apexes of the two of projections are separated by a clearance space for solid and gas to flow.
The reaction zone is contiguous with the pre-heating zone and the reaction zone is a horizontal zone considerable MS section higher area of the pre-heating zone or a is a vertical zone and has marginally higher cross section area than pre-heating zone and has opposed parallel surfaces.
Brief description of the accompanying drawing
In the accompanying drawings: -
Figure 1 schematically illustrates a preferred Reactor for carrying out the method of the invention while
Figures 2 and 3 schematically illustrate various embodiments using the same methodology.
Detailed description of the drawings.
As can be seen from Figure 1, the Reactor "A" principally has a pre-heating zone-B and a reaction Zone C. There is provided an inlet D for coal particles vertically from the top of the preheating zone. The pre-heating zone B is also provided with a hot gas inlet E at a level slightly lower than the coal particle inlet but from the left side wall of the pre-heating zone.
The wall opposite to gas feed wall is provided with a first internal surface (F1) inclined towards the interior at a predetermined angle. Similarly at a lower level, the opposite wall of the preheating zone is provided with a second inclined surface (F2) preferably identical
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to the first inclined surface (F1). In the same manner, further inclined surfaces (F3) and (F4) are also provided each on the respective opposite walls. These inclined surfaces are formed as projections preferably as truncated conical projections towards the interior of the pre-heating zone. The distance between the inner ends of the opposed projections is kept preferably uniform.
The number of projections and the distances between them is as per exigencies and requirements.
The bottom of the pre-heating zone is extended at 90° into a horizontal reaction zone (C).
The operation is as follows: -
Coal is admitted into a flowing gas stream and the coal particles, which fall vertically, are thrown to the opposite wall due to the impinging gas just above the opposed inclined surface (F1). The particles are then thrown on the opposed inclined surface (F2), then on (F3) to (F4) and so on until the momentum is reduced to the required extent enabling the pre-heated coal particles to fall vertically on to the bottom of the reaction zone C.
The continued flow of gas now carries the pre-heated coal through the reaction zone for the reaction to be completed.
In this case along horizontal reaction zone is required.
However, various alternatives of vertical reaction zones in continuation of the pre-heating zones are also possible as illustrated in Figures 2 to 4 which are self - explanatory.
The walls are brick-lined.
The inclined surface is essential on the top surface of each projection (F1) to (F4). The bottom surface can be similarly provided, so as to provided a projection tapering towards the interior. However, the bottom surface can also be straight or parallel to the top surface.
Various modifications as can be obviously occur to a man skilled in art are also within the sop of the invention.
This invention is ore fully described with reference to the accompanying drawings wherein Figure 1 shows a schematic representation of a heating zone, Figure 2 represents the Reactor.
On the corrugations on the baffle plates should have a wavy pattern with circles on the rests of the wavy Design. This helps in further rapid heating of cal due to the fact that the portion of the jet, which moves along the side of the corrugation,
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undergoes circular movements along the periphery of the circles causing more mixing, within the
stream between coal and hydrogen.
Examples:
Coal 70% - 200 mesh (5 Kg) impregnated with about 1% Na2C03 using a solution in water (3.2% solid) on the weight of coal with or without low temperature ash was pressurized in a screw feeder and was fed to the Reactor. The Design of Reactor suggested above is mainly for the preheating zone only. Following the pre-heating zone, there is a straight section of pipe where a residence time was given at the same operating temperature for liquefaction. The result obtained for maximum liquid production is as follows:
% of Coal conversion to liquid operating temperature pressure residence time
84 400° C 1000 psig. 10 Sec.
In order to stop reaction such that neither the liquid gets gasified nor char is formed a direct quenching step was effected after the above residence time.
In the bench scale unit, this was achieved by means of a cold trap containing dry ice and methanol. In plant scale, it can be achieved by recycling some of the separated liquid obtained in the process of gas liquid separating section in the downstream side.
It will be seen that the conversion of coal to liquid product is about 84%, which is higher than convention liquid phase hydrogenation of coal where conversion is of the order of 60%. In this process a conversion of about 20% to 25% more than the conventional technique is achieved. Also, this process is faster than conventional process, which requires about 15 minutes compared to the 5-10 seconds of this process.
Further, the Reactor of the liquid phase conventional process is much longer compared to the new Reactor, which is of a smaller size.
Cost, material, time, energy is saved with higher conversion.
Example 2: In another study in the laboratory, example No.1 was repeated but for the following changes.
Amount of coal feed = 5 Kg/hour.
Particle size - Minus 200 mm covering 70%.
Na2C03 incorporate = 1.8% based on the weight of coal

Na2C03 solution in water at concentration of 3.5%.
Reactor pressure = 1500 psig.
Temperature of Reactor = 400°C
Residence time = 5 Sec.
Pressure of coal feed = 1000 stg.
Conversion of coal to liquid = 77%
Yield of liquid = 80%
Observation is because of higher catalyst content more gas is produced and hence the yield is slightly less than in example 1. However, it is still higher liquid phase conversion process and has therefore all the previously stated advantages.
Reactor details Example 1 Example 2
Material of shell MS MS
Corrugate plate MS MS
Reactor constitution
Two rectangular (Mild steel) MS plates were taken and one side of each plate was provided with the corrugations preferably by machining. These two plates were spaced with the corrugations facing each other using two end parts. The fore corners were welded to from the rectangular Reactor.
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Claim
1. An improved method for the liquefaction of coal by solid phase hydrogenation using hydrogen gas, which comprises introducing the coal particles into a pre-heating zone provided with a pair of corrugated solid internal surfaces provided opposedly and in the dose proximity of each other, held at a temperature of around 650° C from the top of the zone, introducing high pressure hydrogen gas at a pressure of 1000 - 1800 psig and at a temperature of 600 - 650° C, at an angle of about 90 degree to the following coal particles below the point of introduction of coal, to impinge upon the stream of coal particles to hit a first internal surfaces of the pre-heating zone and there after hitting a second internal surface opposed to the second surface, then a fourth surface opposed to the third surface and so on until the pre-heated solid material reaches the lower end of the pre-heating zone, where after the preheated solid and the gas are maintained in contact with each other at a reduced gas pressure in a horizontal reaction zone for completion of the reaction, the said first, second, third, fourth and other surfaces being in staggered relationship and wherein the product coal is subjected to a instantaneous direct quenching step by the use of a cooling medium such as methanol and dry ice at a temperature near 0°C.
2. A method as claimed in Claim 1, wherein the coal used in fortified by using an aqueous solution of sodium carbonate.
3. A Reactor for liquefaction of coal by the solid phase hydrogenation method as herein described comprising a chamber having a pre-heating zone, followed by a reaction zone immediately after the said pre-heating zone characterized in that said pre-heating zone is made up of two verticle parallel corrugated surfaces, each corrugation being formed of projected solid unit running across a width of respective parallel surfaces, there being provided a plurality of such solid units in the vertical direction and each unit separated from the next unit by a suitable space and wherein the projections in the first parallel surface are symmetrical to the projections in the second parallel surface and are in staggered relationship with each other, an inlet at its top end for the admission of coal fortified with sodium carbonate, an intet for the pressurized hydrogen gas also at the top end of the chamber at a level slightly below the inlet level for the coal, a plurality of solid inclined units disposed in the pre-heating zone, said plurality of units being opposed to each other in a pair of vertical rows in a parallel relationship and in a staggered fashion, each said unit having three surfaces in the pre-heating zone a) a first top surface b) a second front surface and c) a third bottom surface and wherein each said first top surface is inclined towards the interior of the preheating zone, a reaction zone immediately after the said pre-heating zone.

4. A Reactor as claimed in Claim 3, wherein the first surface is an inclined surface inclined towards the Centre of the pre-heating zone, each said front surface being a vertical surface and each said third surface being preferably an inclined surface divergent towards the wall surface on which it is formed..
5. A reactor as claimed in Claim 3 to 16, wherein the apexes of the two rows of projections are separated by a clearance space for solid and gas to flow.
6. A method for the liquefaction of coal substantially as herein described.
7. A reactor for the liquefaction of coal substantially as herein described with reference to the accompanying drawing.
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There is proposed an improved method for the liquefaction of coal by solid phase hydrogenation using hydrogen gas, which comprises introducing the coal particles into a preheating zone provided with a pair of corrugated solid internal surfaces provided oppositely and in the close proximity of each other, held at a temperature of around 650° C from the top of the zone, introducing high pressure hydrogen gas at a pressure of 1000 -1800 psig and at a temperature of 600 - 650° C, at an angle of about 90 degree to the following coal particles below the point of introduction of coal, to impinge upon the stream of coal particles to hit a first internal surfaces of the pre-heating zone and there after hitting a second internal surface opposed to the second surface, then a fourth surface opposed to the third surface and so on until the pre-heated solid material reaches the lower end of the pre-heating zone, where after the pre-heated solid and the gas are maintained in contact with each other at a reduced gas pressure in a horizontal reaction zone for completion of the reaction, the said first, second, third, fourth and other surfaces being in staggered relationship and wherein the product coal is subjected to a instantaneous direct quenching step by the use of a cooling medium such as methanol and dry ice at a temperature near 0°C. A suitable reactor is also provided.

Documents:


Patent Number 208758
Indian Patent Application Number 04/CAL/2001
PG Journal Number 32/2007
Publication Date 10-Aug-2007
Grant Date 09-Aug-2007
Date of Filing 01-Jan-2001
Name of Patentee AMALESH SIRKAR
Applicant Address 76/A, BONDEL ROAD, CALCUTTA-700 019, WEST BENGAL, INDIA.
Inventors:
# Inventor's Name Inventor's Address
1 AMALESH SIRKAR 76/A, BONDEL ROAD, CALCUTTA-700 019, WEST BENGAL, INDIA.
PCT International Classification Number C 10 G 1/06
PCT International Application Number N/A
PCT International Filing date
PCT Conventions:
# PCT Application Number Date of Convention Priority Country
1 NA