US3061524A - Process for the formation of low volatile char and synthesis gases by the carbonization of coal - Google Patents

Description

Oct. 30, 1962 R. L. SAVAGE 3,061,524

PROCESS FOR THE FORMATION OF LOW VOLATILE 0mm AND SYNTHESIS GASES BY THE CARBONIZATION QF COAL Filed March 5, 1958 HEAT EXCHANGER RECEIVER INVENTOR. ROBERT L. SAVAGE ATTORNEYS United States Paent'o a lia corporation of Ohio Filed Mar. 3, 1958, Ser. No. 718,823 Claims. (Cl. 2029) In the prior processes for gasifying coal, hereinafter known as coal gasification, it has been an object to produce synthesis gas. In general in connection with such processes, the input com-prises steam, oxygen and coals or other carbonaceous materials of various particle size, and the output comprises synthesis gas, i.e., carbon monoxide and hydrogen, sometimes together with other components, and these components are particularly useful in connection with Fischer-Tropsch reaction techniques, producing gasoline. In other products from synthesis gas, including pipeline gas, ammonia, alcohol, etc., sometimes it is desirable to have a ratio H /CO in excess of two for certain of the processes.

This present process attempts to produce a synthesis gas and does so by gasifying coal or other carbonaceous material and produces as a very valuable product, more than just a by-product, a low volatile char, i.e., a char having a volatile content ranging from 10 to percent,

preferably from 12 to 17 percent. This may be compared to a char produced at 900 F. with a limited amount of oxygen-containing material by a process generally referred to as low temperature carbonization. At the same time, this low volatile char, 10 to 25 percent, would be a premium fuel for steam generation, and the synthesis gas would be used in connection with the various syntheses techniques mentioned above.

In connection with many of these low temperature carbonization. processes, the production of tars can amount to as much as 40 percent of the revenue and is important in connection with the economics of the process. However, the further processing of these tars is expensive, and it is often difficult to obtain a profitable market for the products. Some of these products are aromatic hydrocarbons and phenols, including toluene, xylene, cresol, and xylenols.

This process takes as input powdered coal, oxygencontaining material and steam but not each of these under all conditions. The steam includes the moisture in the coal. The process converts the powdered coal to a low volatile char by a flash carbonization process taking place within five seconds at a temperature which may range upwards of 1800" F., and under certain circumstances may range down to 1200 F., to convert a medium or high volatile bituminous coal and including lignite and certain other materials into a low volatile char having 10 to 25 percent volatile material which would be a premium fuel for steam generation. This product might be from 70 to 80 percent of the input of the coal to the process, or a lesser percentage, 50 to 80 percent,

of lower rank carbonization material. At the same time;

there would be produced synthesis gas, including substantial portions of CO and substantial portions of H arranged according to the desired useof the synthesis gas.

For background purposes it must be understood that in presently known carbonization processes the devola; tilization of coal takes place by indirect heating of the coal in the absence of air or in the presence of limited amounts of air and steam. The volatilized products are collected as condensedtars and relatively small amounts of gas. Indeed, many of the present processes are similar in some respects to this process, with the pronounced with the principal products being CO and H ice exception that in conventional gasification processes the chars produced do not represent a major product and that in low temperature carbonization processes there is a high component of tars produced. The processes ofc oal gasification use finely powdered coal, oxygen and steam to produce a gas having a relatively low CO content, which is useful for various chemical syntheses. j

A distinction must be made in connection with these. processes between carbonization, -i.e., the transformation of organic material into coke and charcoal by distillation natural gas and oil, it is imperative to gasify allof the coal, but this is d-ifiicult to do in the conventional gasification apparatus because an excess of carbon must be:

maintained in the reaction zone to prevent formation of excessive amounts of carbon dioxide in the synthesis gas.; The unreacted carbon from a conventional gasificr isvery high in ash content, perhaps as much as 60 to per-,-

cent and it has relatively little value as a fuel. Sometimespart of the material isrecycled in these'conventional' gash: fier processes, but this requires an increase in size and;

in capital investment in order to maintain the same rate of generation of synthesis gas. In general, three approaches have been taken in coal; gasification systems and these approaches include fixedbeds, fluidized beds and entrainment systems. Until comparatively recent times the fixed beds had perhaps the widest commercial use, and this would be the standard;

In this system cokewater-gas set and the gas producer. rather than coal was the most 'frequent' material gasified.

The fixed bed systems have certain advantages, but the? use ofcoal in the fixed beds provides a problem in connection with the ash, and since most coals have a plastic;

range in which they melt or else a range in whichthe'y disintegrate and may have an ash fusion temperature below the desired reaction temperatures, they resultfin poor fuel beds. Coke is consequently the material used; and this requires initial preparation of the coal for use The product in these instances has very high ashcontent.- In connection with the fluidized beds, various problems arise with regard to the volatility of the coal, determining its plastic range, disintegrating tendencies and the fusion problem.- The entrainment systems have another" series of disadvantages, but they do tend to be independ' ent of the specific coal properties, such as. the plastic" range, the ash fusion temperature, and this is applicable" to any coal.

For the above reasons it would seem that animpro'ved'i process to avoid someof the limitations of the present.

andreprocessesas briefly outlined would be apparent quired.

This present invention is a flash 1000 p.s.i.g. with oxygen-containing material, principally oxygen, though air may be used under certain -circum stances,..and possibly the use of some recycled gas, toj .gether with a limitedamount of steam and/or the-mois'-- In order to compete with the cost of synthesis gas from other sources, such as from carbonization, process. directed to the production of a low volatile charas a; substantial product and synthesis gas with lowtar forma-; tion and will take place at upwards of 1200" F. and under ture in the coal. It will operate with an oxygen ratio from .10 to .30 lb. of oxygen/lb. of coal. It will produce gases having a varying content, though not necessarily limited to these exact percentages, of to 55 percent CO and from 21 to 48 percent hydrogen, and at the same time percentages from 0.1 to 20 methane, from 0.2 to 9.8 CO and from 0.3 to 18.3 H O as steam, and from 0.4 to 0.6 percent nitrogen except where air is used, in which case it may range up to almost 50 percent nitrogen. As a solid by-product there would be a low volatile char from 69 to 80 or 85 percent of the coal input.

An object of this invention is to provide a new and improved flash carbonization process producing a low volatile char and synthesis gas without tar formation.

A further object of this invention is to provide a flash carbonization process using oxygen-containing material and carbonizing without substantial tar formation to produce a low volatile char and a gaseous mixture containing hydrogemcarbon monoxide and methane.

A further object of this invention is to produce a large quantity of a premium fuel from a flash carbonization process involving coal and oxygen and a certain amount of the moisture in the coal without substantial tar formation.

A further object of this invention is to produce a syn thesis gas containing hydrogen and nitrogen in the ratio for ammonia production by the use of oxygen and oxygencontaining material and coal in a flash carbonization process producing a large quantity of low volatile char and substantial quantities of synthesis gas.

A further object of this invention is to produce a twostep process, the first step being a flash carbonization process having as an input oxygen-containing material and coal with the possibility of using additional steam and recycled gas and producing a low volatile char, and the second step being to further reform the gases with steam in a water-gas reaction.

To the accomplishment of the foregoing and related ends, said invention then consists of the means hereinafter fully described and particularly pointed out in the claims; the following description setting forth in detail one approved means of carrying out the invention, such disclosed means, however, constituting but one of the various ways in which the principles of this invention may be used.

The accompanying drawing is a diagram of said process.

In this process a low volatile char and synthesis gas are produced without tar formation by interacting bituminous coal and/or other carbonaceous material with oxygen and a limited amount of steam, which includes the moisture in the coal, in a continuous flow system, preferably an entrained system, though the invention is not limited thereto. This process is particularly adapted for powdered coal of medium volatility, i.e. 21-35 percent V.M., or high volatility, i.e., 36-45 percent V.M., bitu minous coal or lignite, the latter being a coal of very low fixed carbon (-40 percent moisture), and having as a typical analysis 33 percent C, 26 percent V.M., 41 percent H 0, and perhaps 8,300 B.t.u./lb. or less. In addition to this, medium volatile bituminous coals and high volatile bituminous coals including the A and B type having fixed carbons from 69-78 percent for the medium volatile and 22-31 percent volatile matter, and more volatile matter and less carbon for the high volatile coals may be used.

An example of the coal that would be useful in connection with the process is the Edenborn coal which, when carbonized by conventional methods at a fast coking rate in an oxidizing atmosphere of 900 F., produced the following products per 100 lbs. of coal:

As an example of the process these materials were fed from a powdered coal feed bin 10 by the flow of superheated steam or steam plus recycle gas from the process, i.e., CO plus H as shown at 11. Oxygen enters at 12 into the flash carbonization chamber shown generally at 13. There is an inlet tube shown at 14 and an alloy steel inner container shown at 15 of lesser diameter than the refractory lined flash carbonizer 13. The reaction of coal, oxygen and steam takes place in the center tube of the flash carbonizer. The amount of heat involved is a function of the ratio of steam to oxygen to coal, and these are shown in connection with the tables which follow.

It is, of course, to be understood that other kinds of flash carbonization chambers may be employed. It may be desirable to have a series of inlets, possibly tangential, into the flash carbonization chamber of steam and/or oxygen at various points along the chamber. The flow of the mixture of powdered coal plus such an amount of steam or moisture plus oxygen through the center reaction tube may be either streamlined or turbulent depending upon the type of coal being used. For coals which tend to soften and agglomerate on heating the streamlined flow conditions would be preferred. This would be accomplished by keeping the conventional Reynolds numbers for the gases below 2100 and preferably below 1200. For non-agglomerating coals, higher flow rates may be utilized. The operating ratios in connection with this would be as follows:

1,000 .s.i.g. 1,200 to 2,500 r Below 200 mesh to inch.

p.s. .g. 1,800 to 2,200 F.

Minus 4 to plus 100 mesh.

Operating temperature. Coal size 11; is realized that this may be from 0.001 to to 0300 under certain conditions.

Some volatilization of the coal will take place in the reacting zone. The degree of volatilization and the reaction of the coal may be controlled by adjusting the relative amounts of steam, oxygen and coal, the temperature and pressure in the tube and the diameter and length of the tube to produce a char in this system having a volatile content between 10 and 25 percent, in general, this is preferred to be between 12 and 17 percent. The bottom of the carbonizer as shown at 17 serves as a disengaging member to separate the hot char from the gases and tar vapor. The gases and tar vapor pass upwardly in the outer annular chamber shown at 18. As the gases and tar vapor pass upwardly in the annular chamber 18 at lower velocity and high temperature, additional cracking and a reaction of the tar vapor with oxygen and steam takes place with the resulting complete gasification of the tar vapor and forming additional amounts of carbon monoxide and hydrogen and smaller amounts of other gases, such as methane, ethane, etc.

In general in connection with these reactions, the tar formation continues to be very low if the proper conditions result above 1800 F. However, the gasification process can be continued at lower temperatures provided careful control is exercised as shown in the examples which follow. The time in connection with this process would be less than five seconds. If the higher velocities are needed to control the reaction time in the flash carbonizer, part of the gaseous products may be recycled back through the blower as shown at 20 with superheated steam. This is shown in one of the examples. The bypass is shown at 21 and is taken from the outlet of the annular chamber in the flash carbonizer as at 22. In-

.5 stead of passing to the waste heat boiler shown at 23, it. by-passes through the channel shown at 24. As indicated, the gas products leaving the flash carbonizer 22 pass into the waste heat boiler 23 and pass out to a conventional recovery and storage system as indicated at 26. At the bottom of the flash carbonizer the process steam is shown at 27. This is the output of the waste heat boiler from the top of the boiler as shown at 28. A quench zone occurs following the mixture of the processed steam and the hot char as at 2, and these products pass into a cyclone separator shown at 30. It is, of course, to be understood that other means for quenching the char may be used and the disengaging section above mentioned may be of different construction also. The gaseous products would pass out through the top of the cyclone indicated at 31, and the solid particles of quenched char would be taken from the bottom as indicated at 32 by means of a screw conveyor and/or other closing apertures for the cyclone generally indicated at 33. This quenching operation is at a low enough temperature to prevent further reaction of the char. Some CO plus H will be generated during this quenching operation, however. The char produced by this process would be suitable for burning in conventional coal burning or cyclone-type combustion equipment.

Following are seven operational procedures underneath this process, some using oxygen without steam'with one using air instead of oxygen. The pressure varies in other of the processes, and the full range of the chemical conditions applies in the cases. It may be that more than one reaction tube will be required and secondary feed of steam for increasing the water-gas reaction may be required in a second combustion chamber, i.e., it may be a two-step process. Similarly, oxygen and/ or coal or steam may be fed in at various angles and possibly with a certain vortical movement to the main face of the stream in order to provide improved mixing conditions.

EXAMPLE 1 In this example I used the minimum oxygen to burn this particular coal which produced, when carbonized with a fast coking rate in an oxidizing atmosphere at 900, a char equivalent to about 78 lbs/hundred lbs. of coal, together with tar, lbs/hundred lbs. of coal, and gas in the amount of 7. 1 lbs., and liquor in the amount of 4.8 lbs. The material in connection with the coal and gas and the other characteristics are shown in Table 3. Table 1 shows the material balance for the seven cases, and Table 2 shows the heat balance for the cases. (See cols. 8, 9 and 10.

The lower limit in connection with this first example of the amount of oxygen which is about .10 lbs. of oxygen/lb. of coal is used without any steam and without air and recycle gas. p.s.i.g. This yielded 822. standard cubic feet/ hundred lbs. of coal, of which 721 consisted of hydrogen, CO and CH and the gas composition was as follows.

Gas composition:

This produced solids including char, 80 lbs/hundred lbs.

of coal, and carbon was deposited in the amount of 1.9

The pressure in this case was 500' Percent vol. (wet basis) 6 ucts, together with a sensible heat in the product gases and the sensible heat in the char, so a heat deficiency resulted which must be made up by preheating the oxygen.

e EXAMPLE 2 Here again no steam, air or recycle gas was used, but a greater amount of oxygen was, i.e., .231 lb. O /lb. of dry coal, and this appeared to be closer to the preferred condition. Both 0 and 500 p.s.i.g. gauge were tried. The gas yield totaled 954 standard cubic feet/hundred lbs. of coal, only 681 being hydrogen, CO and CH The gas composition percent of volume on a wet basis was:

This produced a low quality of gas with an excess of heat having a relatively high CO content, 9.8 percent, and this produced 78 lbs. or" char/hundred lbs. of coal.

EXAMPLES 3 and 4 In these examples, steam, air and recycle gas were absent, and the same amount of oxygen was used. However, in Example 3 the pressure was atmospheric, i.e., 0 p.s.i.g., and in Example 4 it was 500 p.s.i.g. At these pressures the gas compositions were: 3

Example 3 Example 4 O O 65. 4 45. 0 CF. 0. 1 2. 7 CO 0.2 5. 9 H p 43. 6 37. 7 H20 0. 3 8. 2 N2 0. 4 0. 5

Char in the amount of 69.18 lbs/hundred lbs. of coal was produced. However, a heat deficiency de.-. veloped. In Example 4 at the higher pressure less gas was produced with more CO and less CO and H A greater amount of char was produced, 73.4 lbs/hundred lbs. of coal, but no heat deficiency developed. In fact,

an excess WasprOduced. In the third example 8.3 lbs.

of carbon Wasgasified/hundred lbs. of coal. This was considered slightly high for routine conditions. At the higher. pressure in connection with Example 4, only 4.7 lbs. of carbon was gasified/hundred lbs. of coal.

': EXAMPLE 5 In thisexamplethe higher pressure was used and produced less carbon gasification, but air was used in place of oxygen. No recycle gas or steam was used. Here a first effort was made to produce a gas that might approachthe ratio for ammonia synthesis gas. The following gas composition resulted:

c0 25.2 CH4 0.8 c0 i 1.9

H2-- 21.0 H 0.- 2.5 N2 48.6

lbs, This indicated that there was insutficient oxygen to 7 completely oxidize the carbon, and some carbon deposited Char in the amount of 72 lbs. was produced, and 6.1 lbs. of carbon was gasified. A heat deficiency developed which 'wasremedied by heating the air to 1220 F. The

ratio of H 'to N was inadequate, and supplemental synthesis gas was needed. This was supplied from a second carbonizer.

EXAMPLE 6 This example is similar to Example 4, except that steam is subtituted for oxygen. It is to be understood a,oe1,524

U that this steam includes the moisture in the coal. In this example .05 lbs. of steam/hundred lbs. of coal was used, and the gas composition was as follows:

This yielded 73 lbs. of char. This example was substantially in balance thermally. It was felt that the preferred range for the amount of steam/lb. of coal was between .001 and .10 lb./lb. of coal, though under certain circumstances the range might be expanded to .001 to .30. It should be realized, of course, that the reaction with steam is endothermic and the conditions must be improved in terms of the heat balance in order to permit this operation to have substantial quantities of steam in the action. This system was adiabatic, i.c., change occuring without substantial loss or gain of heat, and it represented an operating condition for methanol synthesis gas. It was further noted that the ratio of the H /CO was improved by the use of steam.

EXAMPLE 7 In this example steam was used, and this included the natural moisture in the coal, together with a limited amount of oxygen, .147 lb./lb. of coal, and in connection with Examples 6 and 7, the oxygen content was maintained at substantially the same levels and this included the free plus the combined oxygen. However, after a start-up run recycle gas was used to the extent of 20 percent of the oxygen. Recycling resulted in a heat deficiency and lower carbon gasification.

The above examples show that the oxygen may be limited per pound of coal and is in the range .10 to .30 and perhaps preferably between .20 and .25 lb. of oxygen/lb. of coal. This is particularly in the pressure range of 0 to 500 p.s.i.g. gauge. With this amount of oxygen substantial carbonization takes place and with greater amounts of oxygen more gasification and less carbonization would result. When air is used as in Example 5, the limit is about 1 lb. of air/lb. of coal, and at about .5 lb. of air/1b. of coal carbon begins to deposit, indicating the lower limit of air.

It is important to note that this flash carbonization must be held to a minimum time. However, the time must be long enough to insure equilibrium between the gas and the char. If the time is too short, highly exothermic homogeneous equilibrium will exist, and the quality of gas is reduced and a char would be produced which would be equivalent to one formed at a temperature higher than 900 F. This 900 F. char is, of course, a char which has a volatility content of about 10.2 percent. The range of gas temperatures in general was used at about 1800" F. but it is realized this could be scaled down with the possible danger, however, that the tars and other volatiles might be formed. Although the diagram does not show it, it may be necessary to introduce oxygen and recycle char at different points in the carbonizer. This under certain operating conditions might prevent the gases from cooling below 1800 F. and the char from being produced which was not equivalent to that of a 900 F. char. Under these latter conditions a mist of tar and incompletely burned volatile matter might be produced in the discharge gases. It is noted that at higher pressures less char is gasified and more methane, CO and H 0 are formed.

'For the production of certain synthesis gas where the ratio of H to CO is greater than 2, a second reaction vessel may be required, and a portion of the reactants would be mixed with steam after the carbonizer and a two-stage reactor would be required.

In connection with Example 5 where air is used, a gas approaching that of an ammonia synthesis gas was attempted, but the discharge gases would have to be blended with synthesis gas from an oxygen carbonizer in order to obtain a ratio of H /N of 3.

The waste heat boiler as shown in the drawing could be used to recover the sensible heat from the discharge gases as shown in connection with Table 2. This may be in a single stage or in two stages, giving 005 500 p.s.i.g. steam, possibly for use in connection with Examples 6 and 7, and a lower pressure process steam for boiler feed water use. From examining Examples 6 and 7 it will be noted that less than 20 percent of the oxygen can be replaced by recycle gas unless means are used to offset the heat input deficiency resulting from its use.

The tables referred to in the foregoing specification are as follows:

Table 1.-Material Balance Summary for Seven Cases 1 In uts, ##1## coal:

Steam (1600 F.) I 0. 054 0.054 Oxygen 0. 231 0. 251 0. 231 7 0. 183 0.147 Air- 1.0 Recycle gas 3 0.065 Pressure, p.s,i.g 0 0 500 500 500 500 ld SUE/100,; l

e coa 'i iimll 954 1, 215 1, 045 2,112 1, 147 b 1, 01a Hri-CO-i- CH4 681 1, 203 894 1, 020 990 932 Hg-i-CO-I-CHri-Nz- 2,076

Gas (gomposition, o/o vol. (wet basis):

N: Solids yield, #/100# coal:

Char

Carbon gasified Carbon deposited 1 Operating temperatures: 1,800 F.

1 For cases 6 and 7, total free plus combined oxygen input=0.23 1 #0a/100# Coal.

I For case 7, 20% 01 free oxygen in case 6 was replaced by combined oxygen In recycle gas. 4 In case 2, CH4 content was 0.01% at 14.7 p.s.i.g., and 2.5% at 500 p.s.i.g.

5 This does not include recycled gas. Volume ratio of product/recycle=6 9.

Gas composition reached steady state after two recycle stream analyses.

Table 2.-Heat Balance Summary for Seven Cases 7 B.t.u. Per- Btu. Per- B.t.'u, Per- B.t.u. Per- B.t.u, Per- 13.1.0. Per- B.t.u. Percent cent cent cent cent cent cent Heat input, B.t.u.ll00# coal:

Chemical enthalpy of formation I of product gases 70, 496 86 129, 640 100 87, 317 95. 7 112, 692 100 103,085 77. 5 113, 990 91. 9 l 114, 972 80. 6 Sensible heat in steam at 1,600

tat-500 p.s.i.g 10,005 s. 1 10, 005 7.0 Sensible heat in recycle gas at 1,800 F- V 5, 665 4. 0 Heat deficiency 11,039 13.5 3, 900 4.3 29, 892 22. 5 11, 958 8.4

Total 81 535 100 129,640 100 91,217 100 112, 692 100 132, 977 100 123, 995 100 142, 600 100 Heat output, B.t.u.l100# coal:

Chemical enthalpy of decomposition of carbonization prod- V nets 3 26,480 32. 5 25, 480 20. 4 26, 480 29. 0 26, 480 23. 5 26, 480 19. 9 26, 480 21.3 26, 480 18. 6 Decomposition of moisture 4 3, 215 2. 4 31, 211 25. 2 31, 211 21.9 Decomposition of recycle PM 14, 654 10. 3 Sensible heat in product gas at 1, F 29, 895 36. 7 35, 505 27. 4 41,262 .45. 2 38, 250 33. 9 75, 748 57.0 41,824 33. 7 44, 767 31. 4 Sensible heat in 20, 160 24. 7 19, 680 15. 2 17, 590 19. 3 18, 497 16. 4 18, 144 13. 6 18, 446 14. 9 1 13. 4 Heat loss 5 5, 000 6.1 5, 620 4.3 5, 885 6. 5 5, 675 5.0 9, 390 7. 1 6, 027 4. 9 6, 387 4.4 Heat excess 42, 455 32. 7 23, 790 21. 2 7

Total 81, 535 100 129, 640 100 91, 217 100 112, 692 100 132, 977 100 123, 995 100 142, 600 100 1 This deficiency can be overcome by preheating air to 1,220 F.

1 This deficiency can be halved by preheating oxygen to 1,800 F. 3 Adjustment required because heat of carbonization was taken as zero. I For case 5, moisture in air; for cases 6 and 7 steam added. 5 Taken as 10% of sensible heat of products. Must be removed to hold product gas temperature down to 1,800" F.

Table 3.-Basic Data G. Properties of char:

' O A. Carboniz-ation yields of coal (fast coking rate in an g 22:1 :55 oxidizing atmosphere at 900 F.): 0 S o Pounds of product Product per 100 lbs coal H Sensible heat 1n gas at 1800 F Tar B.t.u. per 10. mole at Gas P 1800 F. above 60 F. CH 25,027 Liquor 4. Char 78.1 CO 13159 7 40 2 (s) 16,022 B. Mass balance of elements in gas phase from 100 lbs. H2 12,375 c0a1= 00 20,630 2 13,011 0 13,770 Iloundi Pofund-atoigis F e emen O 0 emen 100 lbs co m per 100 I rom the foregoing it Willi be seen that a umque process coal employing oxygen or air, a limited amount of steam and some recycle gas (providing its limitations are clearly 13.07 1.0881 understood) is produced having a char that is a valuable 5:22 3:223 product with a volatile content of greater than 10, which Nitrogen 0. 36 0.0257 is equivalent to a 900 F. char and useful as a premium C. Heat of carbonization was taken as zero.

D. Heat of formation of carbonization products: 26,480 B.t.u. per 100 pounds coal.

E. Gas analysis- Component Percent by Percent by volume weight F. Tar ultimate analysis:

Percent by weight fuel in connection with power plants and steam generation, and at the same time a synthesis gas is produced that is useful in connection with various syntheses of hydrocarbons and the like. This applies the advantages of a synthesis gas plant together with that of a valuable by-product and is produced without the formation of tars and the difiiculties associated with tar production.

Although the present invention has been described in connection with a few preferred embodiments thereof, variations and modifications may be resorted to by those skilled in the art without departing from the principles of the invention. All of these variations and modifications are considered to be within the true spirit and scope of the present invention as disclosed in the foregoing description and defined by the appended claims.

I claim:

1. A method of flash carbonizing a solid carbonaceous material which comprises exposing said solid carbonaceous material to a temperature of about 1200 F. to 2500 F. at a pressure ranging up to about 1000 psi. for a period ranging up to about 5 seconds and in the presence of about 0.1 to 0.3 pound of oxygen per pound of solid carbonaceous material and about 0.001 to about 0.3 pound of steam per pound of solid carbonaceous material, to convert a minimum of about 50 percent by weight of 1 l the solid carbonaceous material to a low volatile char and also to recover synthesis gases without substantial tar formation.

2. The method of claim 1 further characterized in that up to 20 percent of the oxygen is replaced by recycle gas.

3. The method of claim 1 further characterized in that the oxygen is obtained from air.

4. The method of claim 1 further characterized in that the oxygen is substantially pure oxygen.

5. The method of claim 1 further characterized in that the solid carbonaceous material is entrained, in the synthesis gases and'subsequently separated therefrom.

6. The method of claim 1 further characterized in that the solid carbonaceous material is coal, 70 to 85 percent by weight of which is converted to a low volatile char.

7. The method of claim 1 further characterized in that the char obtained has a volatile content from about 10 to 25 percent.

8. The method of claim 1 further characterized in that 20 the char obtained has a volatile content from about 12 to 17 percent.

9. The method of claim 1 further characterized in that the solid carbonaceous material is exposed in the presence of about 0.001 to 0.1 pound of steam per pound of solid carbonaceous material.

10. The method of claim 1 further characterized in that carbonization takes place at a temperature ranging from about 1800" F. to 2500 F.

References Cited in the file of this patent UNITED STATES PATENTS 1,781,766 Smith Nov. 18, 1930 1,983,943 Odell Dec. 11, 1934 2,534,051 Nelson Dec. 12, 1950 2,572,051 Parry Oct. 23, 1951 2,623,011 Wells Dec. 23, 1952 2,757,129 Reeves et a1 July 31, 1956 2,775,551 Nathan et al. Dec. 25, 1956 FOREIGN PATENTS 716,273 Great Britain Sept. 29, 1954

Claims (1)

1. A METHOD OF FLASH CARBONIZING SOLID CARBONACEOUS METERIAL WHICH COMPRISES EXPOSING SAID SOLID CARBONACEOUS MATERIAL TO A TEMPERATURE OF ABOUT 1200* F. TO 2500* F. AT A PRESSURE RANGING UP TO ABOUT 1000 P.S.I. FOR A PERIOD RANGING UP TO ABOUT 5 SECONDS AND IN THE PRESENCE OF ABOUT O.1. TO O.3 POUND OF OXYGEN PER POUND OF SOLID CARBONACEOUS MATERIAL AND ABOUT 0.001 TO ABOUT 0.3 POUND OF STEAM PER POUND OF SOLID CARBONACEOUS MATERIAL, TO COVER A MINIMUM OF ABOUT 50 PERCENT BY WEIGHT OF THE SOLID CARBONACEOUS MTERIAL TO A LOW VOLATILE CHAR AND ALSO TO RECOVER SYNTHESIS GASES WITHOUT SUBSTANTIAL TAR FORMATION

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