US2443854A - Fluidized-solid process for forming carbon disulfide - Google Patents

Description

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fo Amma?" Patented June 22, 1948 FLUIDIZED-SOLID PROCESS FOR FORMING CARBON DISULFIDE Robert P. Ferguson, Cranford, N. J.. assignorto Standard Oil Development Company, a corporation o! Delaware Application March 6, 1943, Serial No. 478,310

The present invention relates to the production of carbon disulfide by a cheaper and more eiicient method than that which has been hitherto practiced. The invention will Ibe fully understood from the following description and the drawing.

The drawing is a semi-diagrammatic view in sectional elevation of an apparatus for producing carbon disulfide by an-improved method and indicates the ilow of the materials.

Carbon disulde is made at the present time by the direct union of carbon and sulfur. -The reaction is strongly endothermic and proceeds only at a high temperature. At present the procedure is to attain the heat by striking an electric arc between carbon electrodes in a furnace packed with coke through which sulfur vapor is passed. The cost of the electric current is high and the method seems unreasonably expensive for most localities.

In the present invention a method has been devised for obtainingA the heat for the reaction and the temperature required by the combustion of a portion oi' the coke and it is consequently cheaper since this form of heating is much less expensive than electrical methods. It has further advantages in that the method is totally continuous and is subject to a close, accurate control. Other advantages will be apparent to those skilled in the art.

Referring to the drawing, numeral l denotes a reaction vessel, preferably in a cylindrical form, which is divided into three separate zones, an upper heating zone marked A, a middle or reaction zone, B, which is in several reaction sections as will be described later, and a lower preheating zone C. These zones are separated from each other by solid cross-sectional plates 2 and 3. zones A and B by the septum 2, and B and C by the septum 3. Powdered coke is fed into an elevated hopper 4 through a double bell valve la, into a dlspersing or suspension chamber 5. Air or other gas is added at the bottom of the zone through the pipe 6 and a dense suspension of the nely divided coke in the gas is thus prepared in 5. Some gas is released through pipe l, preferably to equipment for recovery of the finely divided carbon. This maybe a separate device or the pipe 1 may be connected into the top of the zone A, as will be explained below.

AThe dense dispersion of coke in gas is conveniently described as being in a suspended condition and the mixture acts in many ways like a liquid and is capable of flowing through pipes, valves, chambers and conduits, and shows both static and dynamic heads. The suspended coke from the chamber 5 passes down through feeding standpipe 8 and into a rising pipe 8, which leads directly into the zone A of the reactor. Air is supplied by a pipe I0 and it is preferably preheated at Il before it passes into the pipe 9. If

desired. it may pass directly into the zone A, that is .before admixture with the suspended coke. The air is insuflicient for the complete combus-v tion of the entire amount of coke fed, but is sumcient toburn enough coke to raise the remainder of the suspended mixture to an elevated temperature of the order of 1400 to 1600 F.

Reaction vessel i may be lined with i'lrebrick, not shown, or otherwise adapted to withstand this high temperature and the mixture of air and solid gas is added at the bottom of the zone A, preferably beneath a grid or screen Il which acts as a distributor. Thus within the zone A, the finely divided coke in a highly heated condition is suspended in the combustion gas. From the top of the zone part of the gas is removed through a cyclone separator I2 which is iinely constructed in the top of the zone A. Clean gas is taken by pipe Ii to a heat exchanger t4 and thence toa stack which is not shown.

Vaporized sulfur is supplied through a pipe I5 and is carried through the heater I6 wherein'it is highly superheated before passing by a pipe IB into the lower portion of zone B of the reactor I. The zone B is divided. as indicated above, into a series of reaction sections by means of grids marked Il. In this case three such sections and three grids lla, Hb and llc are shown, but it will be understood that two or more than three sections may be lemployed if desired. The pulverized. suspended coke is fed into the uppermost section of zone B directly from zone A lby means of a pipe Ia, which passes through the grid Il and through the septum 2. This pipe, I Ba, discharges into the uppermost section of zone B and preferably there is some dispersing plate or battling means to give the dispersion an upward motion into the zone. From the uppermost section the uidized coke passes downwardly to the lower sections successively by pipes I8b and I8c and then from the lowermost section into zone Cof the reactor by a pipe I8d. It will thus be seen that the fiuidized carbon ilows down through the several sections of zone B in a roughly countercurrent relation to the vaporized sulfur which passes upwardly through the several sections of zone B. The conversion to carbon I disuliide occurs during the passage through the disulfide. the vapor or formed passes up through zone B, finally ilnding that compound as it is exit by a pipe I9 which preferably connects with `a hot, dust separator 2l which returns finely divided coke dust to zone B. The carbon disulde vapor is then condensed in 'a cooler 2l and is collected in a reservoir 22. f

The powdered solid leaves the lower section of zone B by means of a pipe "d and\ir the flow of the two materials is so controlled and if a sumcient number of sections are provided in zone B, the solids in this fluidized mixture are largely ash and free from carbon, but it will be still at a high temperature 'and can be used to preheat at least a portion of the air used for the process, so

that it is desirable to feed the air by the pipe 23.

beneath the grid 24 within the zone C. If some carbon is still contained in the ash, it can be conveniently burned within this zone and thus the carbon will be used to supply preheat. The hot gases pass out of zone C by a pipe 25 which joins pipe I0, mentioned before. The ash is removed from zone C by a pipe 2B.

It will be understood that the solids throughout the entire reaction zone are in what has been termed a fluidized" state and the streams flow downwardly from zone to zone while the vapors and gases gradually pass upward through the apparatus. Within the reaction zones the finely divided carbon and the vaporized sulfur are as thoroughly admixed as possible and in continual agitation so that the reaction proceeds rapidly and efficiently. Within each of the sections B, the agitation is suilicientlv great so that each section will be held at approximately the same temperature. This effect may be further enhanced by passing a. portion of hot suspended carbon directly from the pipe 9 into the several sections of B by means of separate pipes 21. The tlow down the pipes marked I8 is controlled by dampers or other types of valves which Aare shown on the drawing.

I n order to maintain the solid in a thoroughly iluidized or suspended state, it must be reduced to a ne powder, preferably not greater than 50 mesh, and it is usual to employ powders of say 100 to 200 mesh or even liner. Gas must be added to these powders in a certain minimum quantity or the order of 1 to 2 cubic feet per 100 pounds of solid in order to eilect the rluidization. I! less gas be present, the solid will have a tendency to pack and will notfiow through the a-pparatu-s smoothly, but if a good iiuidized suspension is obtained and velocities are kept within prescribed limits, there is little tendency for thel solids to pack and to plug valves or lines. Quantities of gas, considerably greater than the minimum specified above, can be added to the suspensions without undesirable eiects and flow of the fiuidized suspensions can be effected without the use of pumps or fans acting directly on the 4 total diameter of the reaction zone. This is suilicient to maintain the suspension and to bring about the desired agitation. It the velocity is much above this ligure, the amount of iluidized carbon carried overhead is considerably increased and while that is not greatly objectionable. it rcquires larger dust separating capacity than is required with the velocities set forth. The tem- Parature within they reaction zone is within the range of 1400 to 1600 just as is used in the present method, and it will, of course, be understood that the reaction itself proceeds in this same general manner, but more rapidly in the present case because of the finely divided condition of the coke. The heat for the reaction, as has been mentioned before, is supplied by the combustion of a portion of the carbon and is carried in by the highly heated carbon which is to take part in the reaction. The required heat amounts to about 52,000 B. t. u. per pound of carbon disulfide formed. Most of the burned carbon is inthe form of carbon monoxide and the gas y recovered may be employed forvarious purposes. For example, it may be burned to carbon dioxide to furnish heat for various preheating some of the reactants. It may be employed in gas engines for furnishing power or for other purposes. such as for the conversion with steam to produce a gas rich in hydrogen.

1. A process for the continuous production of f carbon disulde which comprises forming a suspension of powdered carbon in a gaseous stream comprising vaporized sulfur,l said carbon being of such particle size that a majority will pass a 200 mesh screenl maintaining said suspended carbon in a iiuidized state in a reaction zone at a temperature between approximately 1400 F. to 1600 F. for a time su'ftlcient to form carbon disulfide, continually adding more carbonand vaporized sulfur, continually removing the gaseous products from the reaction zone and recovering carbon disulfide, and continually removing spent ash from said zone. t

2. A process for the continuous production of carbon disulde which comprises forming a. suspension of powdered carbon in a gaseous stream comprising vaporized sulfur, said carbon being of :such particle size that a majority will pass a 200 mesh screen, maintaining said suspended carbon in a uidized state in a reaction zone at a suitable reaction temperature and for a time sufficient to form carbon disulide, continually adding more carbon and vaporized sulfur, continually removpowdered solid by conveniently adjusting the den.-

sities of the suspensions. Thus, the density in the down pipe 8, which conducts the original suspended carbon from the chamber B, will be considerably greater than the density of the suspension in the rising pipe 8, because ci the gas added to pipe 9 by I0, so that the suspension prepared in the chamber 5 will be conducted down the pipe 0 and upfthrough the pipe 9 without the use of pumps or fans as indicated above.

'I'he velocityof flow within the tower is an important factor and preferably should be held within the range of 1 to 5 cubicfeet per second, that'is to say the upward flow of gas based on the ing the gaseous products from thereaction zone and recovering carbon disulfide, and continually removing spent ash from said zone.

3. An improved process for producing carbon disulfide which comprises continuously supplying powdered coke to a vertical reaction zone. passing vaporized sulfur into the bottom of the zone and maintaining the velocity of the vapors such that the solid coke particles are maintained in a fluidized condition therein, adding air to generate heat for the reaction, withdrawing vaporized carbon disulfide and separately withdrawing a stream of iluidized solids rich in ashy constituents.

l 4. An improved process for producing carbon disulfide which comprises continuously passing vaporized sulfur into a reaction zone, continuously passing finely divided carbon suspended in a gaseous vehicle into said zone, maintaining a reactive temperature of 1400 to 1600 F. in said reaction' vaporized carbon disulfide and recovering the same free from solid carbon.

5. An improved process for producing carbon disulde which comprises passing a stream` of finely divided carbon suspended in a gaseous vehicle through a series of reaction zones wherein the carbon is maintained in a uidized condition by addition of a further gaseous constituent, passing vaporized sulfur through said zones, removing vapors of carbon disulfide, separating solid carbon therefrom, condensing the carbon disulfide and continuously withdrawing in a separate stream uidized solid rich in ashy constituents of the carbon.

6. An improved process for producing carbon disulfide which comprises preparing a stream of powdered coke suspended in air, burning a portion of the coke to raise the remainder to an elevated temperature, then passing the heated suspended carbon so obtained downwardly through a series of reaction zones wherein the carbon is maintained in a uidized state, passing vaporized sulfur through said zones in the opposite direction, removing carbon disulnde so formed as a vapor, separating powdered solids therefrom, condensing the vapor and collecting the carbon disulfide.

7. A process according to claim 6 in which the heat for the reaction is supplied by the incoming stream of said heated suspended carbon.

8. A process according to claim 6 in which hot streams of' said heated suspended carbon are fed into the separate reaction zones to maintain them at the desired reaction temperature.

9. An improved process for producing carbon disulde which comprises preparing a stream of iinely divided coke suspended in a gaseous vehicle, passing the stream downwardly through a series of reaction zones wherein the coke is maintained in a iluidizcd state by addition of vapors thereto, adding air to the iirst of said zones to burn a portion of the coke thereby heating the remainder to an elevated temperature, passing the stream through the series of reaction zones, passing vaporized sulfur countercurrently through these zones, withdrawing carbon disulfide vapor formed in the reaction, recovering and condensing the carbon disulfide, withdrawing a stream of suspended solids from the reaction zone and directing the same into a preheating zone and passing air through the preheating zone for obtaining preheat.

10. A process for the continuous production of carbon disulfide which comprises forming a mix' ture comprising a suspension of powdered carbon in a gaseous stream comprising vaporzed sulfur, said carbon being of .such particle size that a majority will pass a 200 mesh screen, maintaining said mixture in. a nuidized state in a reaction zone at a temperature between approximately 1400 F. to 1600 F. for a time sunicient to form carbon disuliide, continually adding more carbon and vapcrized sulfur, continually removing the gaseous products from the reaction zone and recovering carbon disulnde, and continually removing spent ash from said zone.

ROBERT P. FERGUSON.

REFERENCES CITED The following references are of record in the'

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