US2334555A

US2334555A - Catalytic apparatus

Info

Publication number: US2334555A
Application number: US393916A
Authority: US
Inventors: Frank A Howard
Original assignee: Standard Oil Development Co
Current assignee: Standard Oil Development Co
Priority date: 1941-05-17
Filing date: 1941-05-17
Publication date: 1943-11-16
Anticipated expiration: 1960-11-16

Description

Nov. 16, 1943. F. A. HOWARD 2,334,555

CATALYTIC APPARATUS Filed May 1'7, 1941 3 Sheets-Sheet l 6A5 OUTLET ACTIVATION R SECTION Nov. 16, 1943. F, A, HOWARD CATALYTIQ APPARATUS Filed May 17, 1941 3 Sheets-Sheet 2 Nov. 16, 1943. F. A. HOWARD 2,334,555

\ CATALYTIC APPARATUS Filed May 17, 1941 s Sheets-Sheet 5 FIG 5 pearly/Iva .DRUM

CRACKING ZONE FRAcT/QNA TING To W572 FEE 0 line T HEATING O O O Patented Nov. 16, 1943 CATALYTIC APPARATUS w floward, Elisabeth, N. 1., assignor to S Oil Development Company, a corporation of Delaware Application May 17, 1941, Serial No. 393,918

7Claims.

claims, reference being had to the accompanying drawings.

As is known in the catalytic cracking of hydrocarbons, as heretofore generally practiced, the process is characterized by the feature that after the catalyst has been in operation for a period of time it becomes progressively contaminated with carbonaceous deposits and when the amount of carbonaceous deposits is about 2% by weight of the catalyst, it is necessary to discontinue the cracking operation to regenerate the catalyst; thus, for example, in the so-called "tray type" reactor where a stationary catalyst in the form of lumps, granules, pills, etc., is disposed in the reactor on a'pluralityof spaced perforated trays and where the hydrocarbons undergoin conversion pass through the several trays in series, the process is necessarily intermittent as regards a single reactor, for the reason stated previously, namely, that the catalyst becomes contaminated with deposits of carbonaceous material which impairs the activity of the catalyst and hence the conversion be discontinued so that the catalyst may be regenerated by removal of the deposits, preferably by combustion.

My present invention relates to a process of continuously cracking hydrocarbon oils and to means for carrying out the operation continuously.

The main object of my invention is to carry out catalytic reactions continuously and in vapor phase, employing a solid catalyst, by moving the catalyst in a substantially circular path, successively in contact with reactable vapors, with a gaseous purging medium, with a gaseous regeneration medium, with a second purging medium and repeating the cycle indefinitely, while continuously feeding reactable vapors to an active catalyst and continuously recovering reaction products therefrom.

A second important object of my invention is to control the angular velocity of a cracking catalyst, such as an acid treated Montmorillonite clay, moving in a substantially circular path through an environment into which gas oil vapors heated to cracking temperatures are prwent, so as to avoid the deposition of more than 2% by weight of carbonaceous deposits on the catalyst and preferably to avoid the deposition of more than 1.0% or less of such contaminating material.

As a corollary to the next preceding object, I propose to operate a cracking process in relatively short, repeated cycles of cracking. Purging, regeneration of catalyst and a second purging so that the amount of carbonaceous material deposited on the catalyst during the cracking phase of a cycle is not more than 1% or so by weight, based on the catalyst, and hence the time period of the regeneration phase may be correspondingly reduced, thus increasing the life of the catalyst by decreasing the time period of each regeneration phase with its accompanying exposure of catalyst to high temperatures during the regenerating periods.

Other and further objects of my invention will appear from the following specification and claims, read in conjunction with the accompanying drawings.

In the drawings, Figure I shows the plan view of my improved tunnel, Figure 11 is a fragmentary showing of the cracking section of my improved tunnel and Figure III is a diagrammatic showing of my complete cracking plant.

improved plant comprises a brick or otherwise refractory tunnel 50 which is suitably supported as on columns or standards 5|. The tunnel 50 is in the form of an annular chamber. Disposed within said tunnel is a movable enclosed metallic catalystcarrier having perforate side walls iii, an imperforate floor and an imperforate roof 66. 60 conforms in shape to tunnel 50 and is of such dimensions as to nearly completely fill the space within tunnel 50, there being Just sumcient clearance between the tunnel and the carrier to permit free movement of said carrier. The inner walls of tunnel 50 arevlined with metal or otherwise finished to provide smooth surfaces. The said clearance between the inner surfaces of the walls and roof of tunnel 50 and the vertical walls and roof of carrier may be of the order of A to /2 inch at operating temperature.

A seal is provided to prevent escape of gas or vapor inside the tunnel 50 as follows: floor 65 of carrier 60 forms the bottom closure of both the tunnel 50 and carrier 60. The vertical walls 8| carry flanges 62 to which shafts 63 are securely affixed and upon a projection of the said shafts, castors or rollers 64 are mounted. Rollers 64 are positioned in raceways 61 and afford the support means of carrier 60 as well as the means by which the carrier may be moved through the tunnel. A liquid such as anthracene oil or any oil resistant to cracking, molten lead, liquefied salts, etc., are disposed in races or grooves 61, the level of the liquid being above the top of castors 84, thus sealing theinterior of tunnel It, together with the metal lined inner surfaces of said tunnel, against the escape of gas.

A boss I is cast, bolted or otherwise secured to floor ll of carrier 00 and a downward projection of said boss is integral with a ring Sear I2. I2 intermeshes with pinion I4 securely mounted on rotatable shaft II which shaft at its lower end carries securely mounted bevel gear 'Il. Bevel gear I'I securely mounted on a driven shaft I8 engages gear II. Also mounted on shaft I8 is a reduction box It adapted to control the rotary speed of shaft II. A prime mover 82, such as an electric motor, constitutes the driving means for the driven mechanism hereinbefore described and the driving means 82 carries driven shaft 83 connected to reduction box I9. Preferably the driving means and its power transmission means is enclosedin a suitable housing means disposed beneath the surface of the earth.

As to the tunnel l0 and carrier 60, the same are provided with a plurality of spaced manholes (not shown) to provide ingress means for workpurging gas and may be of the order of from 0 to lbs. per square inch gauge pressure.

The carrier 60 is caused to rotate during the operation of my plant and as previously indicated the catalyst moves through the four phases representing the cycle of cracking, purging, re-

- purging and regeneration zones for a period of men to make necessary repairs, to introduce or remove catalyst and the like.

Referring specifically to Figure I, my improved plant consists of a cracking section I, a purging section B, a regeneration or reactivating section R. and a second purging section D. It will be noted at first that, as shown, the regeneration and purging sections are wider than the cracking section and as will more fullyappear hereinafter, the reasons for the greater width of these sections is first that of ingress for repairs or substitution of catalyst, but perhaps more important is the fact that a much larger volume of gas is passed through both the regeneration section and the purging sections than pass through the cracking section. Also to prevent intermixing between regeneration gas and the oil vapors in the cracking section, the gas pressure in the purging sections is greater than the pressures in the regeneration and cracking sections.

Referring now to the cracking section, vaporized gas oil at a temperature within the range of from about 825 to 950 F. is discharged into the cracking section through inlet conduits I 5, passes circumferentially through the catalyst and is withdrawn through outlet l6. Preferably conduit I6 carries a suction pump II to assist in the flow of hydrocarbons through the catalyst. The

' inlet pressure of the hydrocarbon vapors into cracking section I should obviously be suillcient to overcome the pressure drop through the cracking section. Ordinarily an inlet pressure of 15 lbs. per square inch gauge pressure is sufficient although higher or lower pressures may be employed.

Asto the purging sections B and D, steam or other purging gas, such as flue gas, CO2, etc., say at a temperature of 825 to 950 F., is discharged from pipe 20 into pipes 2| and 22 and thence into the purging sections. The purging gas should have an inlet pressure of about 18 to lbs. per square inch gauge. The purging gas serves to dislodge either hydrocarbon vapors or regeneration gas from the catalyst and the purging gas is from about 5 to 10 minutes, thus a complete cycle requires from 25 to 50 minutes. Of course, longer or shorter cycles may be employed and in most cases due principally to limiting catalyst contamination a cracking phase of 10 minutes gives best results.

Referring to Figure III. in order to describe a complete process, insofar as cracking is concerned, a gas oil having an A. P. I. gravity of about 18 maybe introduced into thesystem through line I, preheated in coil 3 of furnace 4 to a temperature of from about 825 to 950 F., thence withdrawn through transfer line I5 and discharged into cracking section I where it contacts the catalyst and undergoes conversion to yield about 30% to 40% gasoline having an octane number of '79 to or higher, depending on the nature of the charging oil. The reaction products are withdrawn through line It, discharged into a fractionating column 5 and there separated into desired constituents. For example, a fraction containing gasoline, excess butane and lighter hydrocarbons is withdrawn through line 'I and dischargedinto a receiving drum II from which normally gaseous hydrocarbons may be recovered through line I! while gasoline may be recovered through line I4. A light gas oil may be recovered from column 5 through line 6 while a heavier fraction may be withdrawn from the system through line B, or recycled, at least in part, to feed line I through line 9.

To recapitulate briefly, my invention comprises carrying out a catalytic cracking operation continuously by moving a catalyst through a cracking zone containing vaporized hydrocarbons, thence through a purging zone, a regeneration zone and a second purging zone. Meanwhile the hydrocarbon vapors move circumferentially through the catalyst in the cracking zone, underheated steam say at a temperature of 800 to In the cracking section the catalyst substantially fills the space comprising said section whereas in the purging and regeneration section the chambers in which the regeneration and purging are carried out preferably are much wider than the cracking section and the catalyst does not therefore completely occupy the regeneration and purging chambers. Thus, the purging and regeneration sections may be from 1% to 1% times as wide as the cracking section.

Thevertical dimensions in all sections are preferably substantially equal. I'he greater width of the purging and regeneration sections is to induce radial flow of gases through the catalyst therein. Of course, there may be some circumferential flow depending on the speed of rotation of said catalyst but the prevailing flow is desirably radial,

in other words, the reverse of the flow of oil vapors in the cracking section which is predominantly circumferential.

Many modifications of my'invention may be made by those skilled in the art.

What I claim is:

1. The combination with an oil preheating furnace and fractionating equipment adapted to condense and separate hydrocarbon vapors into separate liquid products, of a tunnel consisting of a cracking section, a purging section, a regeneration section and a second purging section in the form of a substantially annular chamber, of a closed movable catalyst carrier in the form of a hollow ring and having an imperforate roof and floor and perforate vertical walls, disposed within said tunnel and extending therethrough, the said er having dimensions such as to provide a cebetweenthecarrierand th cracking section ofthetunnel, driven means connected to said carrier, driving means for said driven means, fluid sealing means cooperating with the floor of said carrier to prevent escape of vapors or gas from the tunnel, conduit means for supplying vapors and gas to the tunnel so constructed and arranged as to permit free movement of the carrier during the discharge of vapors and gas into said tunnel.

2. The combination set forth in claim 1 in which the internal width of the purging and regeneration sections are substantially greater than the width of the cracking section.

3. The combination set forth in claim 1 in which the internal surfaces of the tunnel are smooth.

4. The combination set forth in claim 1 in which the carrier is supported on castors arranged in spaced relationship in said tunnel and in operation are disposed in a sump of liquid located at the lower part of said tunnel through which liquid they are caused to move in a substantially circular path by the driving means.

5. An apparatus adapted for converting hydrocarbons which includes a tunnel comprising a cracking section, a purging section, a regeneration section and a second purging section in the form of a substantially annular chamber, a movable closed catalyst carrier in the form of a hollow ring and having an imperforate roof and floor and perforate vertical walls and disposed in said tunnel, said carrier having a relatively small clearance with said cracking section of saidtunnel, means for moving said carrier in said timnel, fluid sealing means associated with said carrier to prevent escape of vapors or gas from said tunnel, means for supplying vapors and gas to said tunnel and means for withdrawing products of conversion and gas from said tunnel.

8. An apparatus according to claim 5 in which said cracking section of said tunnel is of a different internal width from said purging sections.

FRANK A. HOWARD.