US2030852A

US2030852A - Process of distilling coal

Info

Publication number: US2030852A
Application number: US319798A
Authority: US
Inventors: George A Berry; Alling P Beardsley
Original assignee: NAT FUELS CORP
Current assignee: NAT FUELS CORP; NATIONAL FUELS Corp
Priority date: 1928-11-16
Filing date: 1928-11-16
Publication date: 1936-02-18
Anticipated expiration: 1953-02-18

Description

Feb. 18 1936.

G. A. BERRY ET AL PROJESS 0F DISTILLING COAL Original Fil'ed Nov. 16, 1.923 2 Sheets-Sheet 1 32% yv zm'ons 2g. BY; I ,5 g l ATTORNEYS Feb. 18,1936. G. A. BERRY ET AL PROCESS OF DISTILLING COAL 2 sheets-sheet 2 Original Filed Nov. 16, 1923 ATTORN EYJ Patented Feb. 18, 1936 UNITED STATES PATENT orrlcr. I

Beardsley, Plainfield,

N. .L, assignors to National Fuels Corporation, New York, N. Y., a. corporation of New Jersey Application November 16, 1928, Serial No. 319,798 Renewed May 14, 1935 16 Claims.

The primary object of this invention is broadly the transformation of bituminous coal into a carbonized fuel, closely resembling anthracite, and into other valuable products. Another object is to accomplish the above at such a low cost as to be commercially profitable.

By this invention we are also able to recover very valuable commodities from the so-called slack which is produced in enormous quantities in the mining and transportation of bituminous coal and which has been considered as of so little value as to command only a small fraction of the price of the bituminous coal itself.

By this invention the coal is transformed into the following commodities:

A. An acceptabie substitute for natural anthracite which will in some respects be the superior and in others the equal of the natural product, being (1) in pieces of desirable size, (2) of sufiioient strength for handling, (3) of (4) of not too rapid or active combustion, (5) of sufiicient ignitability, (6) of smokeless combustion, (7) sufiiciently free from dust or fines, (8) of low ash content when made from suitable bituminous coals, many of which are of much less ash content than the average anthracite and (9) of high calorific value per volume unit.

B. A high yield of organic liquids condensible at ordinary temperature and in primary condition or, in other words, in substantially the same condition in which they were first evolved from the coal and hence practically unchanged by cracking or otherwise.

C. Gases and vapors not condensible at ordinary temperatures and of calorific value considerably higher than ordinary coal gas.

D. Gases of less calorific value not condensible at ordinary temperatures.

These commodities are productible from a wide variety of grades or characters of bituminous coal, of which for example the coal fields of eastern United States afford a practically unlimited supply.

From the description given later on in connection with the drawings it will be found that this treatment is accomplished in stages, each of which involves its current of heatingv gas, namely:

1. The first stage involves the heating of the coal by passing a current of hot gas, such as coal gas of a temperature between about 275 C. and 400 C. therethrough until the temperature of the coal reaches a predetermined point, above 55 which appreciable amounts of tar vapors or proper density in the lump (i. e. 1.2 or higher),

hydrocarbon products condensible at ordinary I temperatures would appear. The maximum temperature reached in this stage will depend upon the nature of the material which is being treated, but we have found that with coal of the Pocahontas or New River type the temperature of the coal in this stage will ordinarily reach somewhere between 275 and 400 C-. The increment of temperature of the coal per unit of time during this stage can be quite rapid (e. g. at the rate of 5 C. rise per minute) without injurious efiects. 2. In the second stage substantially all the tar vapors as well as the hydrocarbons condensible at ordinary temperature are removed from the coal by the current of gas which may be coal gas and a small amount of permanent gas of very high calorific power is removed at the same time. During this stage the coal becomes plastic and the temperature of the gas passing through the coal is gradually raised from that at the end of the first stage until the temperature of the coal reaches about 500 C. During the whole or a part of this stage the coal would swell to an extent incompatible with the desired density of the final product if the rise of temperature were as rapid as it may be in other stages. To obviate this danger the rate of increase of temperature of the. coal does not exceed the rate which tests have shown to be permissible for the particular coal, which rate may be, for example, with Pocahontas or New River coal, less than about one-fourth of a degree C. per minute, during the period when this danger exists. In general the larger the briquette or lump the slower will be the rate of temperature increment. 3. In the third stage a current of gas such as coal gas of still higher temperature beginning at the temperature of that at the end of the second stage is passed through the coal, during which time permanent gas of less high calorific power than that evolved during the second stage, is obtained. The rate of increase of the temperature of the coal during the third stage may be quite rapid (e. g. 5 C. per minute) without danger of causing the coal to swell. The solid product usually shrinks more and more as the temperature rises during this stage, thus acquiring increased density and hardness. The final temperature of the carbonized residue may be from about 600 to 900 C. according to the re-. activity and density desired in the final product.

4. A fourth or cooling stage may be used in which a current of cool gas, such as coal gas, is passed through the retorts for cooling the residue before it is discharged from the retorts into the atmosphere, thus preventing the same from igniting, and recovering the heat therefrom. The temperature of this gas should be low enough to reduce the temperature in the retorts below the ignition temperature of the residue in a reasonable time.

For practical purposes we regulate the temperature of the coal in all stages by the temperature and rate of flow of the gas entering the retort.

The process by which said transformation is accomplished is of low cost. It avoids deposition of tar on coal of decidedly lower temperature than the temperature of evolution of the tar, and the subsequent distillation of this tar and the consequent degradation of its value. The very rich and valuable gas evolved in stage 2 may be withdrawn from the system for subsequent disposal, as for example, for enriching city gas.

This process comprehends the treatment of not only bituminous coal of one type but blends of several types thereof and also blends of bituntnous coal with anthracite, semi-anthracite, su bituminous, lignite, semi-coke and coke, all of which types and blends, as well as briquettes made from same whether with or without binder, we include in the expression coal to be treated. Such blends will often permit a more rapid rate of temperature increment during the second stage of carbonization and often give a more dense fuel.

In the accompanying drawings, Figs. 1 and 2 represent diagrammatically two examples of arrangements of apparatus which may be employed in the above transformation. Although batchwise systems are shown we are not to be understood as limited thereto.

In Fig. 1, reference character I indicates a series of vertically disposed retorts that may be provided with openings at the top for introducing the material to be treated and openings at the bottom for withdrawing the treated material. A conduit 2 for gases leads to the upper ends of the retorts I and a conduit 3 leads away from the lower ends of the retorts. The conduit 3 is provided with two branches one of which leads through valve 4 to stack 5 and the other through valve 6. Beyond valve 6, the conduit 3 is divided into two branches,

one of which is provided with valves 1 and'8 nearits opposite ends and the other of which is provided with valves 9 and I0 near its opposite ends.

A heat accumulator II is located: between the branches and may be of any of the well-known types in which heat is stored by hot gases during one period of time and is given up for heating gases during another period. A valve I2 is provided in the conduit 3 beyond the heat exchanger II and another branch I3 leads from the conduit 3 through a boiler so that all or a portion of the hot gases can be passed through the boiler I4 for generating steam and cooling the gases.

A blower or compressor I5 is provided beyond the boiler for circulating the gases through the retorts I. A branch I6 leads all from the conduit 3 between the boiler and the blower. Branch It leads through a cooler I'I that may be cooled by cold water, for example, and then to a gas holder I8. From gas holder I8, a pipe I9 provided with valve 20 conducts the gas away for purposes outside the circuit.

A branch 2| leads from conduit 3 from a point between the boiler I4 and blower I5 to blower 22 and then to heat exchanger 23, which may be of multitubular type. pipe 23' leads to cooler or extractor 23A for condensing or extracting the condensible products from the gas, the non-condensible vapors and From heat exchanger 23 agas passing through pipe 23" to heat exchanger '23 but to the opposite side of the tubes from that of their first passage through heat exchanger 23.

From heat exchanger 23, a pipe 24 leads to and joins pipe 25 coming from blower I5. Pipe 24 is provided with avalve 26 close to its junction with pipe 25. A valved branch of pipe 24 leads to a superheater 21 that may be heated by combustion of gases extracted from the products being treated or may be heated in any other convenient way, as by a supply of combustible gas delivered through pipe 28 and valve 29. For simplicity only one superheater with its connections has been shown in the drawings, but it is to be understood that at least two are provided, so that one may be heated while the other is supplying heat to the circulating gas.

Pipe 24 is provided with a branch leading to valve 30 through which gas may be passed through superheater 21 and out through valve 3| and pipe 32 which joins pipe 25. Pipe 24 is also provided with a branch leading successively through

valves

33 and 34 by which gas can be admitted to superheater 2'! to be burned by air entering through pipe 35 and valve 36, the products of combustion passing out through pipev 31 and valve 38 to exhaust flue 39.

Pipe 25 is provided with a valve 40 before its junction with pipe 32. After junction with pipe 32, pipe 25 leads to gas mixing chamber 4|, the

outlet of which extends through a connection having a valve 42 into the conduit 2.

Still referring to Fig. 1, the operation will be described in connection with the treatment of bituminous coal of the Pocahontas or New River 1;:

type, but it is to be understood that the invention is not restricted to this particular coal or to the exact procedure outlined below. The gas employed is to be practically non-oxidizing on the coal and preferably non-reactive in other respects. The word gas is used herein in the broad sense including vapor. The word nonoxidizing is used herein as signifying the substantial non-transfer of oxygen from the gas to the coal under existing conditions. A suitable gas is that evolved from the coal itself by carbonization. I

The coal may be prepared in briquets of the desired size (e. g. 2 oz.) either by subjecting the coal particles to high pressure alone or by the use ofpressure with a binder. Or lumps of raw coal of the desired size may be used.

The operation is as follows:

It will be assumes that the heat exchanger II is at a temperature of about 700 C. from a preceding run; that the water in the-boiler I4 is at about 200 C. corresponding to the desired steam pressure; that the superheater 21 is heated to a ill temperature of about 900 C.; and that gas is in gas holder I8. The

valves

40, 42 and 4 are opened long enough to permit gas from gas holder I8 to pass through the coal in retorts I and sweep out the air. When the air has been removed the valve 4 is closed, the valve 6 opened are open so that very little, if any, of the gas will pass through the boiler I4 or the superheater 21.

heater 21, while at the same time the gas holder I8 maintains the pressure at the inlet of the blower I5 constant. The blower 22 is not operated during this stage so that none of the gas passes into the heat exchanger 23 and condenser 23A. The heat accumulator II is becoming cooled during this stage. The coal is heated up rapidly at first and then more slowly. Should the heat supplied by the accumulator not be sufficient to heat the material in retorts I to the desired temperature, a portion of the gas is passed through superheater 2'I by opening

valves

26, 30 and 3| and partly closing valve 40. As soon as the temperature of the gas leaving the retorts I is nearly the same as that entering the retorts I, the first stage of the treatment is completed.

For the second stage, the valves 9 and 8 are closed and the valves I and I opened so that all the blower I or the blower 22 can be regulated during this stage by regulating the damper I2 to cause some of the gas to pass through the boiler I4 and become cooled, and the temperature of the gas in the conduit 2 can be regulated by regulating the damper 40 to control the fraction of the gas that passes through the super- The temperature of the gas in conduit 2 should be gradually increased during this stage and this stage is completed when substantially all of the condensible products have been removed from the coal, which will usually be the i case when the temperature has reached about 500 C. At the beginning of this stage of the treatment or as soon as a test sample drawn at the outlet of the retorts I shows the presence of appreciable amounts of tar or condensible products in the gas, the blower 22 is started and run at a speed which will cause part of the gas to pass to heat exchanger 23 and through pipe 23' into the condensing equipment 23A. The non-condensible gas which escapes from condenser 23A passes through pipe 23" into heat exchanger 23 and enters pipe 24. The speed of blower 22 is so regulated that the amount of non-condensible gas passingfrom heat exchanger 23 to pipe 24 is equal to or greater than the amount which it is desired to cause to pass through superheater 21. By this means only such gas is passed through superheater 21 as has been freed from condensible vapors by cool- 1 ing in 23 and 23A. During this stage any excess of gas in the circuit caused by the evolution of gas from the coal or by the increase of temperature accumulates in holder I8, whence it isrwithdrawn as desired through pipe I 9 and valve 20. However, a portion, or all of this excess gas may be consumed during this stage by burning the same in the superheater 21 and not pass into gas holder I8.

During the third stage, blower 22 is stopped, damper 26 is opened and damper 40 is partially or entirely closed, thus causing a portion or all of the gas to pass through the superheater 21 to increase its temperature. This heated gas passes from the superheater 21, through the pipe 32 and chamber 4I into conduit 2 where its temperature will be about 800 C. During this stage the coal will be highly heated and the gas that is evolved at the high temperature will, together ,with the circulating gas, raise the temperature of the heat accumulator II preparatory to the treatment of a second charge of coal. During this stage any excess of gas in the circuit caused by the evolution of gas from the coal or the infrom igniting when removed from the retorts I, it is cooled after the third stage of treatment.

For this purpose dampers I, 8 and I2 are closed while 9 and I0 are opened, thus causing the circulating gas to pass through the coal to ab-' stract heat and to become cooled while passing through the boiler I4. When the temperature of the coal has been reduced sufiiciently, the blower I5 is stopped and the valves 42 and 0 are closed, whereupon the carbonized residue is discharged from the retorts I and a fresh charge of coal to be treated is, introduced into these retorts to be treated.

The example of apparatus of which Fig. 2 is a diagram differs from that shown in Fig. 1 as follows:

A series of vertically disposed retorts I' is provided duplicating retorts I. Conduits 2' .and 3' are provided duplicating conduits 2 and 3. The conduit from mixing chamber 4 I is branched, one branch controlled by valve 42 leading to retorts I and the other branch controlled by valve 42' leading to retorts I'. Conduit 3 is provided with valve 43 and conduit 3 with valve 43'. Beyond valves 43 and 43' conduits 3 and 3 join and the comb'ned conduit is designated as 3.

Heat accumulator II of Fig. l and the valves controlling it are omitted in Fig. 2, conduit 3" leading directly to boiler I 4.

The apparatus shown in Fig. 2 may be operated as follows:-

It will be assumed that retort-s1 are filled with completely carbonized residue from a previous operation at the temperature at which said operation has been completed, which will be about 800 C.; that retorts I' are filled with fresh coal to be treated; that gas is in the gas holder I8. The valves 40, 42', 43' and 4 are opened long enough to permit gas from gas holder I8 to pass through the coal in retorts I' and sweep out the air. When the air has been removed the valve 4 is closed, valves 42, 43 and 6 are opened, and the blower I5 is started, thus causing the gas to begin to circulate through the coal or carbonized residue in retorts I and retorts I Valve I2 is open so that very little, if any, of the gas will pass through the boiler I4. The temperature of the gas entering retorts I should be about 300 C. and this result is obtained by regulating

valves

42 and 42, by which the division of the gas to retorts I and retorts I respectively is controlled. Such a fraction of the gas is causedto pass through retorts I that the temperature of the as in conduit 2 is that desired, namely about 300 C. During this stage the gas holder maintains thgegpressure at the inlet of the blower I5 constant. The blower 22 is not operated during this stageso that none of the gas passes into the heat exchanger 23' and the condenser 23A. The coal is heated up rapidly at first and then more slowly. Should the heat supplied by the coal or carbonized residue in retort I not be sufficient to heat the coal in retort I' to the desired temperature, a portion of the gas from opening

valves

26, 30 and 3|, the superheater having previously been heated up to the desired temperature which may be about 800 0. As soon as the temperature of the gas leaving the retorts l is nearly the same as that entering the retorts, the first stage of the treatment is completed. Then valves 42 and 43 are closed, the coo-led material in retorts l is discharged and the retorts l filled with fresh material to be treated.

For the second stage, the valve 40 is partially closed and the

valves

26, 30 and 3| are opened, thus causing a fraction of the gas to pass through the superheater 21. The temperature of the gas reaching the blower I5 or the blower 22 can be regulated during this stage by regulating the damper 12 to cause some of the gas to pass through the boiler l4 and become cooled, so that the temperature of the gas reaching blower I5 or blower 22 is not high enough to damage those blowers. The temperature of the gas in the conduit 2' can be regulated by regulating the damper 40 to control'the fraction of the gas that passes through the superheater 21. The temperature of the gas in conduit 2 should be gradually increased during this stage and this stage is completed when substantially all of the condensible products have been removed from the coal, which will usually be the case when the temperature has reached 500 C. At the beginning of this stage of the treatment or as soon as a test sample drawn at the outlet of retorts I shows the presence of appreciable amounts of tar or condensible products in the gas, the blower 22 is started and run at a speed which will cause part of the gas to pass heat exchanger 23 and condensing equipment 23A. The non-condensible gas which escapes from condenser 23A passes through pipe 23" and thence through heat exchanger 23 and enters pipe 24. Thespeed of the blower 22 is so regulated that the amount of non-condensible gas passing from heat exchanger 23 to pipe 24 is equal to or greater than the amount which it is desired to cause to pass through superheater 21. By this means only such gas is passed through superheater 21 as has been freed from condensible vapors by cooling in 23 and 23A. During this stage any excess of gas in the circuit caused by the evolution of gas from the coal or by increase of temperature accumulates in holder [8, whence it is withdrawn as desired through pipe l9 and valve 20. However a portion or all of this excess gas may be consumed during this stage by burning the same in the superheater 21 and not pass into gas holder l8.

During the third stage, blower '22 is stopped, damper 26 is opened and damper 40 is partially or entirely closed, thus causing a portion or all of the gas to pass through the superheater 21 to increase its temperature in conduit 2' to the desired point which will be about 800 C. During this stage the coal will be highly heated and gas will be evolved from it. Any excess of gas in the circuit caused by evolution of gas from the coal or by increase of temperature will pass through cooler 11 and accumulate in holder I8, whence it is withdrawn as desired through pipe l9 and valve 20. However-a portion or all of this excess may be consumed during this stage by burning the same in the superheater 21, and not pass into holder 18. During this stage the temperature of the gas reaching the blower 15 may be regulated by regulating the damper l 2 to cause some of the gas to pass through theboiler I4 and become cooled, so that the temperature of the gas reaching blower I5 is not high enough to cause damage to the blower. This stage is completed when the temperature of the gas leaving retorts I is nearly the same as that of the gas entering retorts I.

In order to prevent the carbonized residue from igniting when removed from the retorts, and also to utilize a part of its heat for heating up fresh material, the third stage is followed by a cooling stage. Valves 42' and 43' and 6 are closed and valves 4, 43 and 42 are opened, thus allowing gas from gas holder I8 to flow through pipe 25 into retorts l and displace the air therein. Then valve 4 is closed, valves 6, 42' and 43opened, blower I5 is started, and the gas is caused to circulate through retorts I and retorts I asalready described previously for the first stage.

Many modifications and changes may be made without departing from the spirit and scope of our invention as defined in the claims and the desire therefore is that the foregoing description and drawings be regarded in the illustrative sense rather than in a limiting sense.

We claim:

1. The process of distilling coal by the successive passage of a plurality of currents of heated gas at different times that is substantially nonreactive'with the coal at the existing temperatures, the temperature of each current being independently controlled.

2. The process of distilling coal by the successive passage of a plurality of independent currents of heated gas at different times that is substantially non-reactive with the coal at'the existing temperatures, the temperature of each current being independently controlled.

the coal, that is condensible at ordinary temperature, to the temperature of substantial elimina tion thereof, and the rate of temperature rise during at least a portion of the period of action of said currents being lower than that which would cause substantial swelling of the coal used.

4. The process of distilling coal by the passage of a plurality of currents of heated gas that is substantially non-reactive with the coal at the existing temperatures, the temperature of the coal due to one of said currents extending to a point between 275 and 350 C., and the temperature of the coal due to another of said currents extending therefrom to a point below 550 C.,

and the rise in temperature during a period between said first-mentioned point and 550 C. being at a rate less than one fourth of a degree C. per minute.

5. The process of distilling coal by the passage of a plurality of currents of heated gas that is substantially non-reactive with the coal at'the existing temperatures, the temperature of the coal -due to one of said currents extending to a peratures said gas being substantially non-reactive with the coal at the different temperatures, the temperature of the current while the organic vapors from the coal are being removed, which condense on cooling at ordinary temperatures, being such that the temperature of the coal is increased more slowly than the substantial swelling rate o'f the coal used.

7. In a process of distilling coal while it is stationary by the action of a plurality of currents of heated gas at different times that is substantially non-reactive with the coal at the existing temperatures, blending with the gas a portion of more highly heated gas, the gas to be highly heated having been substantially freed from the vapors of organic compounds condensible at ordinary temperature.

8. In a process of distilling coal while it is staof heated gas at different times that is substantially non-reactive with the coal at the existing temperatures the addition to that current from which condensible organic vapor is being removed of the requisite volume, of gas, not substantially containing condensible organic vapors, to maintain the pressure in the current.

9. In a process of distilling coal while it is stationary by the action of a plurality of currents of 'gas at difierent times that is substantially non-reactive with the coal at the existing temperatures, the compensation of volume of a gas current by returning thereto gas from which condensed vapors have been removed, the excess gas which represents that evolved from the coal being availed of in a substantially uncontaminated condition for purposes outside the circulating system.

10. In a process of distilling coal while it is stationary by the action of a plurality of currents of gas that is substantially non-reactive with the coal at the existing temperatures, dividing the coal into a plurality of charges and timing the action of the respective currentsupon said charges so that a fully carbonized hot charge is cooling at the same time that a raw charge is being heated, and transferring the heat from the carbonized charge to the raw charge by circulation of the gas through both charges.

11. In a process of distilling coal by the action of a plurality of currents of non-oxidizing gas that is substantially non-reactive with the coal at the existing temperatures, passing the gas from a current to a gas holder through a cooler when there is an increase of volume in the current and from the gas holder when there is a decrease of volume in the current.

12. In a process of distilling coal by the action of a. plurality of currents of non-oxidizing gas at different times that is substantially non-reactive with the coal at the existing temperatures, a cooling of the fully carbonized hot coal by the circulation therethrough of colder gas in a closed current, the gas leaving the hot charge being deprived of part of its heat before being returned to the charge.

13. The process of distilling coal while it is stationary by the treatment ir a plurality of stages with heated gas that is substantially non-reactive with the coal-at the existing temperatures, one of said stages extending from the temperature of the substantial appearance of vapor condensible at ordinary temperature to the temperature of substantial elimination thereof, and the rate of temperature rise of the coal during at least a substantial portion of said stage being lower than that which would cause substantial swelling of the coal used.

14. The process of distilling coal by currents of heated gas that is substantially non-reactive with the coal at the existing temperatures, which consists in raising its temperature by currents of heated gases above 600 C. where the desired density and reactivity of the carbonized product are obtained, while limiting the rate of heat increment, during at least part of the stage of vaporizing which produces vapors that are condensible on cooling to ordinary temperature below that which would cause substantial swelling of the coal used.

15 The process of distilling coal in three stages by currents of heated gases, in the first of which the increment of temperature per unit of time is comparatively great until that temperature is reached above which organic vapors condensible at ordinary temperature would be substantially evolved, in the second of which stages the vapors condenslble on cooling to ordinary temperature are substantially eliminated and which stage includes a period of comparatively small heat increment per unit of time, and in the third of which stages the heat increment is more rapid than in the second stage.

16. The process of transforming bituminous coal into a plurality of products such as solid fuel, tar and coal gas which comprises forming the coal into briquets, then rapidly raising the temperature of the same by currents of heated gases to the point above which vapors of organic compounds condensible at ordinary temperatures would be evolved, subsequently distilling tar and hydrocarbons condensible at ordinary temperatures while raising the temperature at a rate not exceeding that which would cause the coal to swell substantially, and thereafter rapidly raising the temperature to about 600 C. to 900 C GEORGE A. BERRY. ALLING P. BEARDSLEY.