US2026355A - Production of activated carbon - Google Patents

Description

1396- 1935- F. H. CONE Er AL PRODUCTION OF ACTIVATED CARBON Filed Dec. 17, 1954 INVENTOR @MW fl W 636 :Q KLQ +M Ill,

Patented oe si, 1 35 UNITED STATES PATENT, OFFICE;

PRODUCTION OF ACTIVATED Frank Henry Cone, Sonthgate, London. and Clive Beckingham Houlder, Herts, England, assignors to Activities Limited, Nottinghamshire, England, a. British company Application December 17, 1934, Serial No. 157,762

In Great Britain June 24, 1933 7 Claims. (cl. 252-3) The present invention relates to the production of activated carbon, for example decolorizing carbon, from such carbonaceous material as will.

evolve gases when heated, such for example 5 as bituminous coal, lignite, peat or wood in finely divided condition. The term carbonaceous ma,

terial" as hereinafter'employed refers to such material.

It has previously been proposed'to utilize such carbonaceous material in the production of ac- .tivated carbon by partially burning the material in a powdered condition in a retort in a limited quantity of air at a temperature of the order of 800 C. to 1000 0., and thereafter maintaining the partially burnt material in suspension in the products of its own combustion until activated.

The present invention comprises a process for the production of activated carbon (for example decolorizing carbon) wherein carbonaceous material of the kind described in a finely divided condition (for example bituminous coal in powdered form) is instantaneously raised to a temperature exceeding 1000" C. (for example 1400" C.) by sudden'introduction'into a zone of 16 incandescent gas so asto decompose it into carbonfand hydrocarbons in a'fraction of a second. The carbonaceous material is by this means practicaliy instantaneously decomposed without the 1 formation of coke, or contamination of the sur- 80 face of the carbon particles. A porous and highly active carbon residue is the immediate result. Thus the extended oxidation by gases required to activate the material in other processes becomes unnecessary, and more economical raw materials '5 containing a high proportion of carbon, such as bituminous coal, may be successfully It is may be ordinary town gas, having, for

$0 example, an approximate analysis comprising 71% hydrogen, carbon monoxide, 2.5%

' .methane, 1-% other hydro-carbons and the bal- I ance beinz' traces of carbon dioxide and nitrogen. Producer gas, water gas, oil or spirit vapour such 66 as carburetted gas, (i. e., vaporised gas made which it can be cooled and separated from the from oils or spirits such aspetroleum or benzone) or the like, may'also be used. The carbonaceous material, together with the gaseous fuel and air, may be injected through a combustion chamber maintained, at a temperature ex- 6 ceeding 1000 C. v

A plurality of flames may be. employed which are caused to' impinge upon one another so as to produce a'zone of intense combustion and turbulence in which almost instantaneous decompo- 1o sition takes place, unaccompanied by shrinkage of the carbon residue, which is left in an activated condition.

After the treatment in the burning flame at a tendperature exceeding 1000 'C.the activation of 15 e carbonaceous material may be enhanced by F maintaining it at a lower temperature (for example 900 C.) for a further period of time after Bases.

The invention-includes apparatus for activating carbonaceous material comprising in combination a combustion chamber, a plurality of burners opening into the chamber for delivering powdered carbonaceous material, air and a gaseous 26 fuel thereto, the said burners being so arranged that the flameissuing from each burner at high velocity commingles. with that or those from an adjacent burner or burners.

Further features of the apparatus are hereinafter described with reference to the accompanying drawing, which illustrates, by way of example and in a diagrammatic form, one form of apparatus in accordance with the invention. I

' In the drawing:-- 3

Figure 1 isa diagrammatic vertical section, and

Figure? is a horizontal section through the furnace chamber upon the line, 22 ofl igure 1.

The apparatus comprises a cylindrical come bustionchamber II the walls of which are lined with refractory material I 2 and which has near its upper end four radially disposed burners or injection nozzles I 3.

The refractory lining I 2 may with advantageconsist of a material which will resist, as far as possible, reaction with the kinds of ash commonly found in carbonaceous materials, such as coal. Highly inert material such as chromic oxide has been found satisfactory. I N 5 The burners I: are arranged in two pairs, one pair being supplied through branches 33 from a pipe I4, and the other pair through branches II from a pipe 30. The branches 33 join one another at a Y junction with the pipe 34 so that u I the gases are evenly divided between the two burners and the same applies to the branches 35 where they join the pipe 36. The pipes 34 and 36 are symmetrical and join at a. Y junction 31 with a supply passage 38 which is connected to an injector 39. In the injector 39 is an air nozzle 40 which delivers preheated air under pressure into the pipe 38 and there is a down pipe 4| for introducing a mixture of coal gas and pulverized bituminous coal. The pulverized bituminous coal is contained in a hopper I6 and is delivered vby a worm ll into a chamber I5 into which opens a gas supply pipe I 9.

The air nozzle 40 draws the bituminous coal and the coal gas through the injector 39 and mixes it with air, the whole mixture being delivered into the pipe 38 and thence distributed through the Y branches uniformly between the four burners l3.

The burners l3 are disposed so that the flames issuing from them meet in. the centre of the upper portion of the combustion chamber ll above a neck I! of refractory material which becomes highly incandescent during the process and serves to increase the rate of combustion. The flames meeting in the centre of the combustion chamber produce a zone of intense turbulence and violent combustion. Owing to the circular form of the combustion chamber the walls reflect the maximum of radiant heat on to the gases in this zone, and the ring l4 further reflects heat thereto.

The nozzles or burners l3 are each provided with a multiple-hole opening which subdivides the gases issuing therefrom into a number of jets and thus shortens the zone of unburnt gas in each flame.

The lower portion of the combustion chamber ll, constituting the bulkof its volume, serves to receive the descending activated material and ases and to maintain them at an elevated temperature lower than that of the flames themselves of the burners l3 for the purpose of further activating the material which has already been rendered porous and active by its instantaneous decomposition. If necessary in order to reduce the temperature in the lower portion of the combustion chamber ll cool'gases may be introduced through the pipes 25. Y

The activated material and gases pass downwardly through a heat interchanger 2| through the outer portion of which there is passed air from a fan 22, and the air thus preheated is delivered to a pipe l8 at a temperature which may beof the order of 350 C. The pipe I8 delivers this air to the nozzle 40 of the injector 39.

The partially cooled gases and carbonaceous material from the chamber H are then delivered into, a scrubber tower 23 and sprinkled with water from a rose 45 which water percolates downwardly over broken filling and carries down with it carbon suspended in the rising gases. The carbonaceous material collects on the bottom of the tower 23 and the gases pass away through a flue 24. The water in the tower 23 is preferably slightly acidulated for the removal of acid-soluble ash in the carbon. The gases have an appreciable calorific value and they may be used as fuel for any purpose desired.

The carbon sludge from the tower 23 may be pumped to filtering apparatus and washed.

It will be understood that the amount of air delivered to the burners I3 is adequate to burn the gas introduced through the pipe l9 but not to cause complete combustion of the carbonaceous material. Some excess air may be introduced for the purpose of burning volatile matter evolved from the carbonaceous material.

On a semi-commercial scale plant, 800 cub. ft. per hour of town gas was injected together with 5 40 lbs. per hour of powdered coal (capable of passing a sieve having 200 meshes to the lineal inch), fed into an injector by means of a screw conveyor, the injector being fed with air preheated to a temperature of about 300 C., under a pressure of approximately 3 lbs. per sq. in. The material was exposed to the high carbonizing temperature of approximately 1400 C. for an extremely short period of time about 1/20th sec., the whole carbonization andactivation, including treatment in the lower portion of the retort at a reduced temperature being complete in about one second.

It is found that the carbon produced by this process is of a flocculent and porous nature, giving extremely good filtering properties with no tendency towards clogging.

Advantage may be taken of the excess heat' generated in this process, by means of heat-exchanging devices, for subsequentheating and 2 5 drying operations.

We claim:

1. A process for the activation of carbonaceous material comprising injecting finely divided carbonaceous material into a zone of incandescent as wherein the material is instantaneously raised to a temperature in the vicinity of 1400" C., so as to decompose the material into carbon and hydrocarbons in a fraction of a second and before oxidation of the carbonaceous material can take place.

2. A process for the activation of bituminous coal comprising injectingthe bituminous coal in a powdered form into a zone of incandescent gas wherein the powdered material is instantaneously 40 raised to a temperature in the vicinity of 1400" C. so as to decompose the coal into carbon and hydrocarbons in a fraction of a second and before oxidation of the coal can take place.

. 3. In the preparation of activated decolourizing 45. carbon, a process consisting in introducing to a reaction zone of incandescent gas, carbonaceous material in powdered form, the temperature of the reaction zone being in the vicinity of 1400 C. and the velocity of the particles of the materialto said zone being such as to ensure that the material'remains at a temperature too low to effect carbonization until it is fully surrounded by the high temperature gases of the zone and thus to decompose the material into carbon and hydrocarbons in a fraction of a second and before oxidation of the carbonaceous material can take place.

. 4. A process for the activation of carbonaceous material comprising injecting finely divided carbonaceous material into a flame of pie-mixed gaseous fuel and air wherein the material is instantaneously raised to a temperature in the vicinity of 1400 C. so as to decompose the material into carbon and hydrocarbon in a fraction of a second and before oxidation of the carbonaceous material can take place.

5. A process for the activation of carbonaceous material comprising forming a suspension of powdered carbonaceous materal in a mixture of 7 gas and air and injecting the suspended material into a flame of incandescent gas wherein the powdered materlalis instantaneously raised to a temperature in the vicinity of 1400 C. so as to decompose the material into carbon and hydrocarbonsin a fraction of a secondand beiore oxidation ot the carbonaceous materialcan take.

burning the gases in the chamber to maintain itat a temperature in the vicinity of 1400 C. and regulating the velocity of the particles of the injected material to ensure that the material remains at a temperature too low to eilect carbonizatlon until it is fully surrounded by the high temperature gases in the chamber and thus decompose the material into carbon and hydrocarbons in a fraction or a second and before 1 oxidation of the carbonaceousmaterial can take place. a I

'7. A process for the 'activationlot carbonaceous material comprising forming a suspension of finely .dirided carbonaceous material in a mixture of gaseous fuel and air, injecting the suspended. material througha plurality oi. ope i s intora combustion chamber, burning the gaseous fuel as it issues from said openinga' directing the burning gases to ram a plurality of flames which impinge upon one. another to produce a zone of intense combustion and a temperature in the vicinity. of 1400 C-., regulating the velocity of the particlesinjected intosaid'zone' whereby the material israised instantaneously to a temperature' in the vicinity.of"1400 C. andthus undergoes carbpnizatio'n and activation-in a fraction v of asecond, thereafter maintaining the activated material lira-further zone at a reduced tempera ture in thevicinity of 900 C, for a further period 01 time,'the'total period of heating in the two zones not exceeding 1 second, cooling theproduct and separating the gases.

' 'FRANK HENRY cons.

CLIVE 'BECKINGHAM noumm.

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