US2482139A - Hydrocarbon conversion - Google Patents

Description

Sep; 2G55, M49, A. H. SCHUTTE HYDROCARBON CONVERS ION ZAS 39 Filed May 28, 1948 uNirEo Il STATES PATENT OFFICE 2,482,139

nYDaocaaoN looNvEasroN August n. Schutte, Hastings on Hudson, N. Y., assignor to The Lummus Company, New York. N. Y., a corporation of Delaware Application May. 28, 1948, Serial No. 29,751 2` Claims. (Cl. 19652) l This invention relates to hydrocarbon conversion and, in particular, to the formation of coke concurrently with the vaporizatlon and crackingof heavy hydrocarbons such as bottoms and hydrocarbon residuals wherein thel coke formed in the aforesaid reaction is deposited on discrete 'particles of a free-flowing non-agglomerating bed moving continuously by gravity alone. It is a continuation-in-part of my copending application Serial No. 577,707, filed February 13, 1945, and

lentitled Improvements in converting hydrocarbons.

It is an object of this invention to make novel provision for the uniform distribution of liquids on the particles of the continuously moving gravity packed bed of contact material which moves downward through' a sealed reaction chamber solely by gravity.

It is a further object of this inventien to provide a new and improved method for securing the conversion of a hydrocarbon liquid in the presence of a continuously moving bed of contact material wherein the. particles are uniformly coated with the non-vaporizable portion of the hydrocarbon.

Further objects and advantages of my invention will appear from the following description of preferred forms of embodiment thereof taken in connection with the attached drawing in which: v

Figure 1 is a view partly in elevation and partly in vertical section of a reaction unit showing one form of liquid distributing means.

Figure 2 is a vertical section on the line 2-2 of Figure 1 on an enlarged scale.

Figure 3 is an elevation, with parts in section and parts broken away, of a modified form of reaction chamber.

Figure .4 is a horizontal cross section, substantially on the line 4-4 of Figure 3.

Figure 5 is a vertical section on the line 5-5 of Figure 4. l

In accordance with my above mentioned application and as pointed out in a copending application Serial No. 3,747, filed January 22, 1948, such application being a continuation-in-part of an earlier,- and now abandoned, application Serial No. 510,119, filed November 13, 1943,l of which I am a coinventor, the disposition of heavy hydrocarbon by-products of cracking, distillation and like operations, comprising bottoms, tars and the like has represented a major operatingproblem in the petroleum industry. While it has been recognlzed that the conversion of a part of these byproducts to coke along with the formation `of useful and valuable conversion products would solve this problem, at least to a large degree, all former attempts have resulted in the use of expensive, cornplicated and cumbersome mechanisms diflicult to service and of relatively low efficiency.

The present invention is particularly adapted to the uniform distribution of these heavy hydrocarbon feeds in liquid or substantially liquid form onto a compact, free-flowing gravity packed bed made up of discrete porous solid particles which move downward solely by gravity and in which the control of temperature and rate of feed of the charge and temperature and rate of feed of the bed, as well as the provision of a predetermined length of travel for bed particles, is so arranged as to avoid agglomeratlon. It has thus been found possible to obtain the continuous desired vaporization of the lighter portions of the charge and to form a dry coke coating on the discrete particles. i

It is to be noted, however, that the uniform distribution of the charge is of substantial importance for if agglomeration occurs the bed stops moving and local low temperatures develop and the entire mass may tend to stop owing.

I have found that it is desirable to avoid the introduction of any air or oxygen containing gas into the reaction chamberv to prevent the formation of combustion products which would tend to dilute the vapors resulting from the hydrocarbon conversion. It is also not only unnecessary but undesirable to increase the temperature of the bed as it flows downward by gravity and preferably the hotter portion should be established at the top so that there is no tendency of the rising vapors to condense and coke on the surface of the reactor.

More particularly referring to the drawings, Figure 1 represents a pilot plant size unit the main body I0 of which consists of a tube of nominal diameter surmounted by a hopper top generally indicated at I2 through which projects the contact material inlet pipe I4. The contact material in turn lis contained in a hopper I6 and the contact material in passing through the inlet pipe I4 into the larger chamber IIJ will form a flowing pile of material the outline of which is shown at I8. The angle of this pile or mass is a function of the angle of repose of the material.

Between the top of the pile I8 and the dome of the hopper I2 is a vapor releasing space generally indicated at 20 from which the vapors may be removed through the line 22. It will, of course, be understood that the contact material "moves 3 downward by gravity out the bottom of the tube I0. Usually a control valve 23 is provided in the outlet pipe.

The feed spreader or distributors in the present apparatus are generally indicated at 24 and as more particularly shown in Figure 2, it conure 2, the openings are on a downwardly inclined angle so that the contact material which passes down through the conduit I4 and as it ows into the piles I8, will be completely coated with the charge. The hydrocarbon inlet is indicated at 28.

It will thus appear that the feed is applied to the discrete bed particles when they are undergoing movement in the flowing piles from the material inlet to the reactor chamber I0. Uniformity of feed is assured; no liquid will be thrown against the wall and premature coking will be avoided. The construction is simple and effective and the feed openings are continuously kept clean by the movement of the particles across their surface.

The discrete particles of contact material may be either inert porous contact material such as Koppers coke, petroleum coke, alundum, carborundum, or other materials or, alternatively, it may be of a catalytic type such as silica gel or other known catalyst depending upon the reaction desired. Preferably the bed particles are maintained in a range of from 116 in. to 3A in. major dimension and they may be in lump, pellet or extruded form. For the conversion of heavy hydrocarbons, it is sufficient if they are introduced in the inlet I4 at a temperature at from 800 to 1300 F. The hydrocarbons will, of course, be introduced at a suitable temperature in the usual range of '700 F. to 900 F. The vapors under such conditions will be of prime value for further cracking, usually having a gas oil composition with low car-bon content so be directly introduced into a conventional catalytic cracking unit for the production of high grade gasoline. If a cracking reaction is desired, the contact material being catalytic, and the temperatures and charge being adjusted accordingly, the vapors will of course be of high quality gasoline type.

Ordinarily the reaction is carried out at relatively low pressures which may range between 2 pounds p. s. i. g. and 60 pounds p. s. i. g., largely depending upon the pressure required to convey the product vapors to subsequent process equipment.

Reference is made to Figures 3 to 5 of the drawing which illustrate an adaptation of the construction shown in Figures 1 and 2 where the reactor generally indicated at 30 is adapted for full size commercial operations and in which from 50 to 300 tons of the contact material will pass through per hour. In such case, the reactor is a tank like elongated enclosure having a cylindrical wall 3I and frusto-conical end portions continuing therefrom and designated 32 and 34, respectively. Leading into the top frusta-conical end portion 32 is the inlet 35 through which the heated porous bed particles are sent to form the free flowing gravity bed. A suitable outlet 36 extends from the lower frusto-conical end porthat they may steam inlet 38 through which sealing steam is v into down pipes or conduits 46 which applied to the interior of the leg to prevent the the like upwardly out the inlet 35.

reactor 30 and feed passage of cracked vapors and through the bed material and A similar sealing steam inlet 39 is provided at the junction of the frustoconical end portion 34 and the outlet 36 to prevent the passage of vaporous products downwardly out of the reactor 30 with the bed particles and coke deposits issuing from the outlet.

As shown, the interiors of the frusto-conical end portions 32 and 34 may be lined with insulation 40 and similar insulation 4I may be provided in the interior of the outer shell of the cylindrical portion of the reactor 30, all of said insulation being arranged between the metallic outer shell of that portion and a generally cylindrical interior metallic lining 42 which prevents abrasion of the insulation by the downwardly passing bed material.

Within the upper part of the cylindrical body of the reactor there is a wall or baille 44 which is provided with a plurality of apertures 45 opening extend into the hydrocarbon feed and vapor release space or conversion zone below `the wall or baille 44 and provide substantially uniform distribution of the bed material fed through the baille. The vapor outlet 4I extends from the feed and vapor release space on the interior of the reactor 30 immediately below the wall or baille 44 to any suitable collecting station to which it is desired to convey the vaporous products of the reaction occurring within the reactor 30.

In the bed feed zone above the baiile or wall 44, the particles are dry, with their pores substantially empty and free of foreign matter, coatings or deposits. These particles are within the temperature range described above. Upon passing downwardly through the downpipes 46 and past the spreaders 48 they enter frustoconical masses or flowing piles or "cones of repose depending upon the shape of the downpipes 46 wherein the particles are in substantial movement. Hydrocarbon liquid supplied by' the spreaders 48 in fine streams is spread upon the moving discrete particles. In the particular case illustrated, the openings 46 are shown as rectangular but they may be of other shapes, including circular in cross section as shown in Figure 2, if desired.

The feed spreading mechanism comprises a plurality of perforate pipe-like conduits 4B all connected with a common header 49. As shown in Figures 4 and 5, the spreaders or distributors 48 are preferably located adjacent the edges of the depending downpipes carbon feed material is contacted with the hot porous moving bed particles issuing from the downpipes 46, as shown in Figure 3.

The feed spreaders or distributors are so located at the edge of the downpipes that the heavy hydrocarbon material comprising the feed is a1-,

46 so that the hydrostreams (as distinguished from atomizing sprays) to the particles which are moving down as flowing piles over and within the frusto-conical portions of the bed, i. e., the cones of repose immediately adjoining the bed material in the interior of the downpipes 46, whereby the feed is applied uniformly to the discrete bed particles when they are undergoing movement in the aforesaid cones of repose or flowing piles. The thus injected feed streams applied at opposite sides of the top portion of each flowing pile are completely confined by the contact material, as shown in Fig. 3, so that the charge liquid will be prevented from carrying outl of the path of the material.

Upon spreading the feed upon the bed particles a part thereof is flashed off or evaporated upon contact with the hot bed particles and withdrawn as useful vapors which may be taken on, for further processing, to any suitable station. The remainder of the feed which does not flash off or evaporate is taken up or received by particles substantially entirely whereby formation of sticky lms between the discrete bed particles sufiicient in depth or thickness to destroy the free flowing properties of the bed is totally obviated. As much as 50% of oil by weight to contact material may be applied without causing agglomeration depending upon the nature of the contact material. An entirely impervious material such as beach gravel will ordinarily receive about by weight of hydrocarbon under my operating conditions.

As these loaded bed particles pass downwardly by gravity as a column of greater horizontal cross sectional area than the streams through the body of the reactor 30, suihcient residence time is provided for the coking reaction to proceed to completion or, in other words, for the liquid hydrocarbon load on the particles to be thermally converted or cracked into lighter hydrocarbon vapors which pass up through the bed to the vapor outlet 41 leaving a residue of dry coke deposit. 'I'he particles in this condition pass out of the reactor through the outlet 38. This residence time at the normal operating temperatures may range from 10 to 30 minutes. In such case a depth of bed below the feed point must be provided which is greater than the free flowing depth of the charge which at the temperatures under consideration has a viscosity of about one-tenth that of water. A minimum depth of ve feet and a preferred depth of thirty to llfty feet is the range for most effective dry coke formation.

The process illustrated by the embodiment of Figures 1 and 2 forms the subject matter of my copending divisional application Serial No. 100.417, filed June 21, 1949, and entitled Method for hydrocarbon conversion.

While I have shown and described a preferred form of embodiment of my invention, I am aware that modications may be made thereto and I therefore desire a broad interpretation of my in- 6 vention within the scope and spirit of the description herein and of the claims appended hereinafter.

I claim:

l. A process for conversion of a charge of high boiling liquid hydrocarbons which comprises passing a compact column of particle form contact material vertically downward through an elongated conversion zone, introducing said contact material at a suitable conversion supporting temperature into the upper end of said conversion zone as a plurality of confined streams of appreciably less cross-sectional area than said compact column to form upon release a series of flowing piles of contact material extending to the upper end of said column and dening a vapor collection space, withdrawing contact material from the lower section of said zone at a controlled rate to maintain the compact column of contact material within said conversion zone, injecting streams of heavy liquid hydrocarbon charge into opposite sides of each flowing pile of contact material in the upper portion thereof, said injected streams being completely conned by said contact material, and withdrawing vaporous hydrocarbon products through the flowing piles and out of the vapor collecting space.

2. The method of converting a charge of heavy liquid hydrocarbons which comprises passing by gravity alone, a compact column of particle form contact material vertically downward through an elongated conversion zone; introducing said contact material into the upper end of said conversion zone in a plurality of confined streams of appreciably less cross-sectional area than said compact column to form upon release a series of flowing piles of contact material extending to the upper end of said column and defining a vapor collection space at the top of said conversion zone; injecting a plurality of streams of heavy liquid hydrocarbon charge into the top portion of each of said flowing piles of contact material, said injected streams being completely confined by said contact material whereby the charge liquid will be prevented from carrying out of the path of the material, and removing the vaporous products of the reaction from the vapor collection space.

AUGUST H. SCHU'I'IE.

REFERENCES CITED The following references are of record in the tile of this patent:

UNITED STATES PATENTS Number Name Date 2,432,344 Sinclair Dec. 9, 1947 2,438,261 Utterback Mar. 23, 1948 2,439,372 Simpson Apr. 6, 1948 2,441,170 Rose et al. May 11, 1948 2,458,498 Bergstrom Jan. 11, 1948

Images