CA1043709A - Method and apparatus for disengaging particles from gases - Google Patents

Abstract

ABSTRACT OF THE DISCLOSURE
Method and apparatus for separating particles such as catalyst particles used in catalytic cracking of hydrocarbons, from gases in which they are suspended or en-trained. The gas-particle mixture moves in a tube or conduit which is vented, through an outlet opening, to a disengaging chamber. The chamber is statically pressurized by its com-munication with the conduit, but there is essentially no gas flow through the chamber, externally of the conduit. A large proportion of the particles are inertially disengaged from the gases as the particles are projected into the chamber through the outlet opening of the conduit, while the pressure in the chamber diverts or deflects the gases angularly through a port in the sidewall of the conduit, directly into a cyclone separator, at lower pressure.
The invention provides unexpected advantages in per-mitting higher operating temperatures, higher throughputs and lower catalyst losses.

Description

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This invention concerns the separation of particulate matter which is entrained or suspended in a gas stream moving in a conduit. The invention arose and finds its most immediate use in connection with the separation of fine solid catalyst particles ; from the gases produced in hydroca~bon conversion processes such as fluid ~ed catalytic cracking processes, and it is therefore primarily described hereinafter in relation to that field of use.
In fluid bed catalytic cracking of petroleum, con-version of heavy or residual oils to lighter hydrocarbon fractions is effected by contacting the oil with a hot, particulate catalyst - as a fluidized bed or flowing suspension. In one widely practiced cracking process known as "riser cracking", this contacting is carried out in a reactor in the form of an elongated upwardly extending tube which is referred to in the industry as a "riser tube".
In this type of process, oil at a temperature of about 500-800 ~. is mixed at the bottom of the riser tube, with hotter catalyst at a temperature of about 1150-1350 F. Contact of the hot catalyst with the oil results in the very rapid generation of very large volumes of gas, which cause transport velocities in the riser tube o~ xoughly 35 to 50 ~eet per second. The cracking reaction continues as the gas-particle mixtu~e moves upwardly in the tube and until the catalyst and gases are disengaged.

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In order to stop the cracking reaction at a desired stage and to prevent degradation of desired products, it is necessary very rapidly to disengage the catalyst from the re-; action products after the desired period of contact. This is commonly done in what is known as a disengaging chamber. For effecting this separation it has been conventional practice to use one or more cyclone separatoxs, gases being separated and discharged through the gas outlet of the cyclone and solids being discharged through a dipleg to the lower part of the dis-engaging chamber. If the degree of separation achieved in a single stage cyclone is not adequate the effluent. containing a small portion of solid particles still entrained in it, may be further separated in a second stage cyclone.
As utilized in hydrocarbon conversion processes of `
;~ the specific type just referred to, this invention is especially concerned with the separation of the catalyst from the gas-catalyst mixture as it comes from a riser tube to the disengaging ~; chamber. In such processes the efficiency of catalyst separation has important consequences~ Catalyst solids which are not ``20 separated and which remain entrained in the cyclone effluent -~
gas are lost to the cracking operation and must be replaced, or recovered and returned to the process, to maintain a given -~
catalyst/charge ratio and to minimize catalyst costs. Moreover, : catalyst particles which travel downstream with cyclone effluent ~ cause erosion of processing apparatus. The need to limit catalyst ; ~losse an ltself become an operating lirit on oil charge rate, ~ 3_ ~.

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! 7 ~3 ~9 and th oo capacity. Further, in operating at high throughputs, temperatures in the disengaging chamber can become so high as to constitute operating limits as metal stress limits are approached.
Although the cyclones used for catalyst separation are already efficient separating devices, being capable of separating up to 99.995% of the catalyst solids, they must handle very heavy loads: in refining operations, catalyst feed rates to the riser may exceed 1,800,000 pounds per hour. It will be apparent that separating inefflciencies of only .005~ can still mean substantial losses in tenms of actual pounds of catalyst.
For these reasons, it has been the o~jective of this invention to provide means for effecting the required gas/particle separation which will permit operating limits to be raised and lower particle losses to be incurred.

Prior Art An early approach taken by the prior art to the problem - of disengaging solids from gases in riser cracking i5 shown in Slyngstead Patent No. 2,994,659. There the riser tube has a . 20 plurality of discharge slots in its sidewall, below a closed upper end. The entirety of the effluent from the riser is dischar~ed - ~ -directly into a disenqaging chamber in which there is a reduction in the superficial velocity of the gas, which permits some catalys :
to settle out. A two-stage series cyclone separator has its inlet open t the diuengaging chamber.

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~ 9 Experience showed that that arrangement was inefficient, and that the degree of disengagement occurring in the chamber decreased rapidly with increases in the superficial gas velocity in the chamber. Above a certain limit ~usually between 3.5 and 5 feet/second, depending upon catalyst particle density and size range, geometry, gas density and other factors), gas flowing at high velocity from the riser outlet through the disengager to the cyclone inlet, simply maintained a large portion of the solids in suspension and carried that load into the cyclones.
The system was effective at low rates, but highly ineffective at high rates required for economical operation.
An alternative approach subsequently taken by the art is that shown in Wickham Patent No. 3,152,066. There the riser tube had a single outlet opening in its sidewall, directly opposite the cyclone inlet. There was a small horizontal gap between the riser outlet and the cyclone inlet, to permit stripping steam in the disengager chamber to be exhausted through the cyclone. The entirety of the riser effluent discharged directly into the cyclone. The outlet gas from the ~irst stage cyclone passed directly into a second stage cyclone. In practice, ~ ~`
that system was also found to be poor in terms of separation results. The cyclone system was very sensitive to pressure fluctuations in the riser J such that riser changes tended to upset the cyclone operation. This was due, at least in part, to catal t surges in the riser and thus in the cyclone. The `~-10~37S19 device shown in the patent was unsuccessful in the industry.
~ It was modified by discharging the first stage cyclone gas ; effluent to the disengaging chamber, and feeding the second stage cyclone from the chamber rather than from the first stage, but those changes made no substantial improvement.
Subsequently to the Wickham type of disengager, the art has more recently gone to use of a "T" shaped header on the end of the riser tube. ~he "T" has horizontally extending arms with outlets opening downwardly to the disengaging chamber, -` 10 away from the cyclone inlet. The degree of separation occurring in the chamber upstream of the cyclone is improved, in comparison to the Slyngstead system, and the superficial velocity limit is higher, but it nonetheless remains a rather sharp limit once reached. Also, the degree of separation tends to vary drastically depending on the height o~ "T" outlet above the bed of catalyst.
The closer the bed to the "~", the poorer the separation and the higher the cyclone loading. Moreover, the downblast of catalyst at rather high velocity causes severe wear problems on the riser, the dipleg and the flapper valve at the end of the dipleg.
Chipley Patent No. 2,648,398 shows an air cleaner ~- comprising an elongated chamber having an inlet in one sidewall with unrestricted communication to the atmosphere, and a dust outlet ening ~mal1er than ~he inlet and aligned opp~site it .' .
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in an opposite sidewall of the chamber. The outlet also opens to atmosphere. Suction is applied an air outlet of the chamber, to draw a~r laterally from the space between the inlet and outlet. Dust particles move laterally to the longitudinal axis of the chamber, across the chamber from inlet through and ; :
out the opposed outlet, while clean air is drawn off longitudinall f Smith NoO 2,540,695 shows a fuel ~conomizer and air cleaner for motor vehicles, in which a funnel-mouthed member, mounted behind the radiator of an automobile, leads inwardly to a tubular baffle which is enclosed within a concentric ilter.
The filter has a nozzle outlet opposite from the funnel-shaped inlet, through which nozzle grit is discharged to atmosphere.
A carburetor inlet leads radial]y from an annular chamber sur-rounding the filter.
Patent No. 3,597,903 shows a vacuum cleaner in which the intake manifold has an endwise opening to a filter bag and an upstream sidewall opening into a secondary filter bag.
The space surrounding the two filter bags is under negative pressure. Dirt is entrapped preferentially, first in the in-line f~ilteF bag, then, when that is full, in the sidearm bag.

, Summary of the Invention ; In accordance with this invention as practiced in hydrocarbon riser cracking processes, the riser tube leads to . a disengaging chamber and opens directly into the disengaging chamber through an outlet opening. The outlet is preerably .~:
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essentially perpendicular to the longitudinal axis of the tube.
The riser has a second~outlet or port which is upstream of the outlet opening, in the riser sidewall, generally parallel to the tube axis. That opening communicates directly with the inlet of a cyclone separator. The first stage cyclone gas discharge may be fed to the inlet of a second stage cyclone.
The disengaging chamber is at a pressure greater than that in the cyclone, and there is essentially no gas flow through it. , The invention makes use of the high velocity of the catalyst particles and gas moving in the riser. The gas, being of low density in comparison to the catalyst, can make the angular turn through the upstream sidewise port into the cyclone, while the dense catalyst is transported by its momentum into the disengager. Thus, the gas is d:irected into the cyclone but the bulk of the particles are projected into the disengager, out of the deflected gas stream. (This may be contrasted with past systems wherein the entire gas/particle stream is directed into ~ the cyclone, and with other systems wherein the entire stream is directed into the disengager.) The disengaging chamber is essentially closed to the ~low of so large a volume Qf gas through it, and there is no substantial flow of gas from the riser through the disengaging chamber. A static back pressure is maintained in the disengaqing chamber ich diverts ~he g~ angularly from the riser so that : :

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104 3;~09 it does not pass through the disengaging chamber, but instead passes into the cyclone inlet. The solid particles, having higher momentum by reason of their higher density, continue traveling in the upward direction in which they were moving in the riser tube, and are not deflected by the backpressure.
They thus exit through the outlet opening of the riser into the disengaging chamber and accumulate as a bed at the bottom of the disengager from which they are drawn for stripping and recycling. The major portion of the solids are thereby by-passed around the cyclone and do not enter the cyclone at all;
a minor portion, which may be of the order of 10-20% of the catalyst, does enter the cyclone, and is separated there.
Several surprising consequences are obtained by practice of the invention. An especially unique and advantageous result is that significantly higher cracking temperatures can be used. Moreover, the superficial velocity of gases in the dis-,~ engaging chamber is eliminated as an operating limit; and, third, there is a dramatic improvement in separating efficiency and stability over a wider range of operating conditions.
Because the riser discharge gas does not flow through the disengager, there is essentially no flow of the gas in the disengager. That is to say, the superficial or space velocity (defined as gas flow divided by cross sectional flow 2rea) is , essentially zero. This factor, which had been a critical upper limit i certain earlier configurations, is no longer a limit.

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;'S)9 With no superficial velocity in the disengager, there is essentially no re-entrainment of particles discharged from the riser, regardless of operating rate. Moreover, since the pressure in the disengaging chamber is greater than the pressure in the cyclone, there is no tendency for the cyclone to discharge gas downwardly through its dipleg, which in itself would tend ; to cause re-entrainment.
The temperature at which the disengager runs can -surprisingly be raised by use of the invention. Many disengaging chambers now in service have been fabricated of metals which will withstand internal gas temperatures up to about 950 F. If modified to incorporate the structure of this invention, it is found that the same disengaging vessel shell can now be run at temperatures of about 1050 F., i.e., about a 100 F. increase, without exceeding metal stress limits. This is an important advantage, since it has been found in recent years that these higher temperatures are desirable in terms of their affects on the cracking reactions. Thus, modification of the riser-cyclone structure in an existing disengager shell structure enables the process to be run at optimum but higher-than-original-design gas temperatures~
The reason ~or this appears to be that a static gas ~oundary layer now overlies the vessel wall and ignificantly reduces heat transfer from the gas to the shell. Thus the sensed ~ -shell temperature is in fact less, at the same riser discharge gas temperature. -; ~ ' '", ~ ' ' :

The invention can best be further described by reference to the accompanying drawings in which, Figure 1 is a diagrammatic elevation of one common type of riser cracker, Figure 2 is a fragmentary ~ertical section of the disengaging chamber of a riser cracker having disengaging structure in accordance with a preferred embodiment of the invention, ~` Figure 3 is a horizontal cross section taken on line 3-3 of Figure 2, and Figure 4 is a fragmentary vertical section of a modified form of the invention.
As previously suggested, the present invention finds its most immediate application in the disengaging o~ catalyst particles from gases in connection with the riser cracking of hydrocarbon conversion processes. For that reason the invention is shown in the drawings with specific reference to that field of use, although this is not intended as limiting. ~ ;~
., In the common form of riser cracker structure, as shown in Figure 1, the oil charge is pumped to the bottom of the riser tube, where it mixes with incoming hot catalyst from the regenerator. Contact of the hot catalyst with the oil rapidly generates a very large volume of qas and cracking occurs as the mixture rises in the riser. The elongated tubular riser conduit ¦ l-ads rtically or angularly upwardly to an elevated disengager 1~ 1 ;' :: . ' ` ` ` . ' 1(3~`')q~9 vessel for separation of the catalyst from the gases. The separated gaseous products are taken off to fractionation for separation into gas, gasoline, light cycle oil, gas oil, and other products. The catalyst accumulates in a bed as indicated by the dotted line, in the lower or stripper portion of the disengaging vessel. Steam is added to the vessel to strip uncracked oil from the ca~alyst particles. The stripped but coke-encrusted catalyst is returned from the stripper to the regenerator wherein coke is burnt off by the addition of hot combustor air, producing hot flue gas as a product. The hot ~; ca~alyst i5 then recycled. A hopper is commonly provided for catalyst storage. For further description of riser cracking, reference may be had to Hydrocarbon Processing, Vol. 51, No. 5, ; May 1972, pages 89 to 92; ibid. Vol. 53, No. 9, September 1974, pages 118-121; or to "Fluidization and Fluid-Particle Systems", Zenz and Othmer, Reinholt Publishing Corp., 1960, pages 7-15.
In the disengaging structure of this invention, as shown in Figure 2, the riser tube 10 enters the disengaging vessel 11 from below and extends, in the embodiment shown, upwardly generally along the vertical axis of the vessel. The space 12 within the disengaging vessel around and above the riser tube is referre~ to as the disengaging chamber. At its upper end, riser 10 is vented directly into cham~er 12 through an ou et opening or port 13, which preferably is an endwise ~- . . . - .

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: opening, perpendicular to the axis of the tube and to the axis of the chamber 12. Above the open upper end 13 of the riser 10 a downwardly facing deflector cone 14 is mounted to the top of the disengager vessel. The purpose of this deflector cone 14 is to deflect catalyst particles which are discharged through riser outlet 13, thereby preventing them from abrading the upper end of the vessel, and also to minimize any "fall back" of particles back into the riser tube through the open end thereof, which might cause re-entrainment.
Spaced a short distance below but adjacent to riser outlet 13 is at least one port 17 in the sidewall of the riser.
The preferred embodiment shown is a balanced or symmetrical arrangement in which the riser is provided with two sidewise ports 17, 17 which are diametrically opposite one another, each of which feeds a separate two-stage series cyclone separation system (best shown in Fig. 3~. Specifically, each sidewise port 17, 17 is connected via a lateral or transiverse conduit, designated respectively at 18, 18 to the inlet of a first stage cyclone 19, 19. The cyclones may be generally in accordance with known configurations, and the cyclones themselves do not comprise the invention. It is important, however, to note that the first stage cyclones are fed solely through the sidewise ports17, and not through the chamber 12. The conduits 18, 18 feed particles : tangentially into the respective cyclones, wherein a fjurther gas/parti e separation }s made. Particles separated in the first¦

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o ~ ~ 1 0~3 stage cyclones 19, 19 are discharged through downwardly extending dipleys, one of which is shown at 20 in Figure 2, with the gaseous effluent discharged at the top through gas outlet conduits 21, 21 which are connected to the respective cyclone bodies through expansion joints as shown at 22.
The upper end of the riser is desirably provided with external stiffening means designated generally at 25, to support the cantilever load of the cylcone separator which hangs from it.

It is also useful to provide a shoe, as at 26, on the side of the riser, to prevent the cyclone from coming to bear on the riser wall.
The gas outlets 21, 21 of first stage cyclonesl9, 19 are respectively connected through conduits 27, 27 to the inlets of second stage cyclones 28, 28 respectively. Where two stage cyclones are used, each second stage cyclone can be con-nected directly to the gas outlet 21 of a first stage cyclone.
The conduits 27, 27 constitute the sole inlets to the second stage cyclones; that is, those cyclones are not fed through or from chamber 12. Expansion joints are provided to accommodate the differential expansion between the two cyclones. The second ~- :
s~age cyclone diplegs, one of which is shown at 29 in Fig. 2, discharge particles separated in the second stage to the bottom of the disengaging chamber. The dipleg should desirably ~,~ terminate above the bed so as not to be covered by it. The gas outlets 30, 30 of the second staga cyclones extend through the disengager vessel and are connected to a manifold leading to fractionators, not shown.
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The disengaging chamber is pressurized, being con-nected directly to the riser, but the catalyst discharge port is covered by the bed of catalyst which thus restricts escape of gases from the disengager. Steam is admitted to assist in the stripping operation (see Fig. 1). The steam flow is very moderate, for example of the order of 1500 lbs./hr. at 150 psi.
Except for the minor flow of stripping steam which percolates upwardly through the stripper, there is essentially no flow of gases through the disengaging chamber.
In operation, the internal pressuri~ation of chamber 12 blocks significant flow of gases into it through riser endwise vent 13. The catalyst particles, having relatively high density and low volume, are carried by their momentum into the riser chamber, but the gases are diverted angularly to the cyclone through ports 17,17. By far the greater portion of the catalyst is separated where the gases are directed angularly sideways while the particles are projected out of the riser, and these particles largely bypass the cyclone system. A minor portion of the particles are not separated, or are re-entrained in the gas and enter the cyclone system. They are largely separated in the first or second cyclones, which carry a much smaller load than in the prior art. There is a pressure drop of about 2 psi i through the cyclones.
Abxuptness of change of direction of gas flow is important to achieving separation, because the particles do not change direction as rapidly as the gas does. In this connection, ,, ~
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it is further beneficial to increase the velocity of the gas/particles stream just upstream of the sidewise ports 17, 17.
For that purpose the invention preferably employs nozzle means in the form of a conical neck or restric~or in the riser, as indicated by the step-down section at 32 in Figure 2. This neck reduces the cross-sectional area of the conduit, so that the stream is accelerated as it moves past.
Alternatively, or in addition, where an assymetrical or an unbalanced cyclone construction is used, it is advantageous to employ a baffle or deflector means, preferably in the form of a deflector plate 33 (see Fiq. 4) which projects angularly inwardly from the riser sidewall just upstream of the sidewall outlet and in line with it, such that particles are deflected away from the sidewall outlet. The plate is preferably angulated ¦ at an angle A, with respect to the vessel sidewall 10, of about ¦ 30, and projects about 15% of the way across the tube diameter. ~ ~;
This further improves efficiency of operation, as will be shown hereinafter.
The following examples and comparisons with other particle disengaging techniques will further illustrate the practice and advantages of the invention.
The data for Runs 1-10 in Table I was obtained with a prior art disengager in which the entire effluent from the -riser tubé was discharged through a sidewise port in the riser, ~thro a lateral conduit directly into the inle~ of a fir6t ,' ~ .
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stage cyclone. There was no endwise vent, and all of the catalyst went into the cyclone system. Also, the gas outlet of the first stage cyclone was vented to the disengager chamber, and a second stage cyclone had its inlet open to the interior of the chamber. Stripping steam from an external source was su~pli~d ~ the dl-onya9 ~h~b~r , : -v~ ~
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The data in Table II was obtained after the structure ~rom which the Table I data was taken was changed to incorporate the vention.

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Catalyst A was a silica-alumina equilibrium catalyst in microspherical particles having an apparent bulk density of .72 grams per cc. Catalysts B and C were of the same general type as catalyst A but had apparent bulk densities of about .82 grams per cc.
The data in both Tables I and II is taken from yield summaries. Where a Run No. is followed by the character A, the data given is the average for a week, rather than being an actual day's data. Stream densities are from Petroleum Tables compiled 10 by E. W. Saybolt & Co., and are based on API gravity of stream according to yield summary. In these tables "Cat. Rate" repre~
sents the rate of catalyst circulation through ~he riser;
"Fxact. Btms. Flow" represents total 10w out of the fractionator bottoms stream; "Fract. Btms. BSW" is the volume percent of catalyst in the fractionator bottom stream~ and "Cat. Loss"
s represents the amount of catalyst not recovered by the cyclones, assuming that all catalyst entering the fractionator leaves in the bottom stream. The catalyst loss in pounds per day was computed by converting the fractionator bottoms flow to gallons per day and multiplying by the volume percent of catalyst in the stream density. The catalyst loss in pounds per barrel of raw oil charge was computed by dividing the loss per day by the raw oil throughput, converted from pounds per hour to barrels per day.
~ y comparison of TablesI and II, it can be seen that the invention markedly reduced average catalyst losses, while ,~ : ~ ' ,~ , ~
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at the same time enabling oil charge rate to be increased.
Comparing invention Runs 11, 12 and 13 with the prior art Runs 6~10, all of which were the same type of catalyst, it can be seen that the average loss per barrel charge was reduced by 52%, at the same time oil charge rate was being increased by 13%. Moreover, chamber temperature could be increased to 1050 F., from the previous limit of 950 F. so that a better quality product was obtained.
The data set forth in Table III following, was obtained from a bench scale separator in which cracking catalyst was suspended in air, rather than cracking gases, and the data does not represent actual cracking runs. In Runs A and B of Table III, the simulated riser tube discharged to the dis-engaging chamber through a "T" shaped header at its upper end, above the catalyst bed at the bottom of the disengager. The "T"
had side holes and a bottom hole through which gases were vented directly to the chamber. A ~irst stage cyclone inlet opened to the chamber, and a second stage cyclone inlet was fed directly from the first st~ge cyclone gas outlet. In Runs C and D, the riser discharged through a "T" having 45 baffles at the outer open ends of the arms to deflect the discharged material downwardly.
In Run E, the riser was vented through an open upper end to the chamber and was connected through a sidewise port, just below the end vent, directly to the cyclone inlet, in accordance with the invention.

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In the runs referred to in this table, as well as the runs in Table IV following, the catalyst used was an FCC
equilibrium catalyst with the following typical particle size distribution:
0-20 microns - 0 wto ~
0-40 microns - 8 wt. %
0-80 microns - 70 wt. %
Bulk density of the catalyst was .8 grams per cc. Separation efficiency is 1 minus the quotient obtained by dividing the catalyst flowing into the first stage, by the catalyst feed rate to the riser.
In Table III, the amount of catalyst collected in the first stage cyclone dipleg shows the completeness of disengage-ment. The invention (Run E) achieved much more compiete recovery;
it had a 7.05~ first stage recovery, in comparison to recoveries -in other systems of from 13.9 up to 42%. Most significantly, the amount of catalyst remaining in the system for recovery in the second stage cyclone was very low~-only .002 lbs.

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Table IV illustrates the results obtained in the same simulated system, comparing the invention ~Runs F and G) with still other systems (Runs H thru P). The structure utilized in Run F was the same as that of Run E. The structure used in Run G was similar, except that a deflector baffle was incorporated in the riser pipe set below the sidewall exhaust by about 1/4 x the riser diameter, in the form of a plate extending at an angle of about 4~ to the riser axis, and pro~ecting across about 1/4 of the riser diameter. The purpose of this plate was to deflect particles away from the sidewise gas outlet. The separator used in Runs H and I had the riser discharging only to the first stage cyclone inlet. The riser was not vented to the disengaging chamber, and the first stage cyclone gas outlet opened to the disengaging chamber and the second stage cyclone had lts inlet open directly to the disengaging chamber. The first stage dipleg -length was one inch measured from the intersection of the cone and dipleg. The disengager in Run J was similar to that in Runs H and I, except that the dipleg length was 24 inches. The dis-' engager in Runs K and L was the same except that the dipleg length was 18 inches. In Runs M and N the riser discharged to the chamber through a "T" fitting having downwardly facing ports.
The two stages of cyclones were connected in series, with the intake opening to the chamber above the "T". Runs 0 and P were simila o Runs ~ and ~ except that ~ "cross" was used on the ,~ ' ~' , ~, :

10~70~:i end of the riser xather than the "T". The cross had four short horizontal arms, at right angles to one another, with downwardly facing discharge openings, the riser being connected to the center of the cross.
Comparison of Run F with Run G in Table IV shows that the use of the deflector significantly increases the separation efficiency to the first stage cyclone (80.6 to 93~). Both of ~; khose runs achieved high separations prior to the first stage of the cyclone in comparison to Runs H, I, J, K and L, wherein 10 nothing was separated prior to the first stage cyclone (the entire riser effluent being conducted directly into the first stage cyclone with no separation taking place in advance). The separation achieved prior to the flrst stage cyclone in Runs M, N, O and P was good, however, the systems tested there fluctuated greatly as to separ~ting effectiveness if the level of the catalyst bed at the bottom of the disengaging chamber was less than ~our inches below a cross or "T" on the riser end.
As a result of this instability, such sysbems would not display .~ uniformly good separations if used in commercial practice where 20 the distance between the bed and the cross can almost inevita~ly be expected to vary substantially in ordinary operations. In comparison, the invention provides ~ood separations without regard bed level, so long as the dipleg is uncovered.

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lO~ t39 In the foregoing examples the riser tube entered the disengaging chamber through an opening in the bottom, and the cyclones were physically disposed in the chamber. Those skilled in the art will appreciate, from what has been said herein, that it is not necessary that the riser enter the cyclone through the ~ottom, and in fact the riser may enter through the side or even he top, and that the cyclones may be physically disposed outside ~f the disengaging chamber, as may be convenient especially in the systems other than hydrocarbon conversion systems. It is ~ot the physical disposition of the cyclones in relation to the l isengaging cha~ber which is important, but rather the fact that i the riser discharges through an endwise opening into the dis-~ngaging chamber and that it feeds through a sidewise opening just upstream of the endwise opening, to the inlet of a cyclone, regardless of whether the cyclone is inside of, or outside of, ~ the disengaging chamber.
; The invention has been primarily described herein in relation to hydrocarbon conversion processes. However, those skilled in the art will recognize that the invention is useful in other catalytic gas phase chamical reactions wherein catalyst ?articles are contacted with chemicals suspended in a fluid chemical stream flowing in a reactor tube, as well as in ~ ;
other instances wherein particles (whethér solid or liquid) are ~o be di ngaged from gases.

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Examples of other fields wherein it is believed that this method and apparatus will be especially useful and which ~ show the wide scope of utility of the invention, include the : gasification of coal, the desulfurization of solid fuels, and heat ; exchangers wherein hot catalyst particles are mixed with incoming gases to heat the latter while cooling the catalyst.
Having described the invention, what is claimed is:

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Claims (20)

The embodiments of the invention in which an exclusive property or privilege is claimed are defined as follows:

1. Apparatus for disengaging particles from a gas stream in which they are suspended comprising, structure presenting a chamber, an elongated tubular conduit through which in use said gases and particles are moved, said conduit having an outlet opening to said chamber, means for moving said gas stream along said conduit from a remote end thereof, toward said outlet opening, said conduit having a sidewall with a sidewall opening therein, said sidewall opening being substantially parallel to a longitudinal axis of said conduit and adjacent to but upstream of said outlet opening, and cyclone separator means having an inlet which com-municates directly with said sidewall opening.

2. The apparatus of Claim 1 further including nozzle means in said conduit for increasing the rate of flow of said gas stream therein just upstream of said sidewall opening.

3. The apparatus of Claim 2 wherein said nozzle means comprises a conical neck section wherein the cross-sectional area of said conduit is reduced relative to an immediate upstream section of said conduit, said neck section being shaped so that in use it accelerates the gas stream as the latter moves past it in said conduit.

4. The apparatus of Claim 1 further including deflector means projecting into said conduit from the sidewall thereof, said deflector means being positioned therein just upstream of said sidewall opening and in line therewith, at such position that particles moving past said deflector means with said gas stream are deflected angularly away from said sidewall opening.

5. The apparatus of Claim 1 wherein said outlet opening is an endwise opening, substantially transverse to the longitudinal axis of said conduit.

6. The apparatus of Claim 1 wherein said inlet to said cyclone separator means is connected directly to said sidewall opening of said conduit.

7. The apparatus of Claim 1 wherein said conduit projects into the interior of said chamber, and said outlet opening is substantially perpendicular to the longitudinal axis of said chamber.

8. The apparatus of Claim 1 wherein said cyclone separator means is itself disposed within said chamber.

9. The apparatus of Claim 1 wherein said chamber is closed to the flow of gas therefrom at a rate equal to the rate of flow of said stream.

10. The apparatus of Claim 9 wherein said chamber is essentially closed to the flow of gas therefrom.

11. The apparatus of Claim 1 wherein said cyclone separator means has a gas outlet extending outside of said chamber.

12. The apparatus of Claim 1 wherein said cyclone separator means comprises two stages of cyclones connected in series with one another, the first stage having an inlet connected to said sidewall outlet, said second stage having a gas outlet extending outside of said chamber.

13. The apparatus of Claim 1 wherein said cyclone separator means includes a dipleg for discharge of disengaged particles, said dipleg discharging to said chamber, above a layer of particles settled therein.

14. The apparatus of Claim 1 wherein said conduit projects generally vertically into said chamber and said sidewall opening is within said chamber substantially at right angles to said outlet opening.

15. In conducting catalytic gas phase chemical reactions wherein catalyst particles are contacted with chemicals suspended in a fluid chemical stream flowing in a reaction tube with resultant production of gases, the method of disengaging the catalyst particles from said gases comprising, discharging the particles from the reaction tube through a particle discharge opening in said tube, said opening leading directly into a disengaging chamber, statically pressurizing said chamber, diverting said gases angularly to the axis of said tube, through a port in the sidewall of said tube in a position just upstream of said particle discharge opening, directing the diverted gases into a cyclone separator, the static pressure in said chamber being maintained at a level sufficiently higher than the pressure in said cyclone separator that said gas preferentially flows angularly from said reaction tube through said port while particles are carried by their higher momentum beyond said port and are discharged inertially through said opening.

16. The method of Claim 15 wherein said chamber is pressurized by restricting escape of gases therefrom except through said cyclone separator.

17. The method of Claim 15 wherein said particles are discharged from said tube and into said chamber in a direction generally parallel to the axis of said tube.

18. The method of Claim 15 further including the step of increasing the velocity of said stream at a point just upstream of said port.

19. The method of Claim 15 further including the step of deflecting said stream angularly away from the said port through which said gases are diverted to said cyclone separator.

20. The method of disengaging fine solid particles from a flowing gas stream in which they are entrained, comprising, conveying said stream at high velocity through a tube having an endwise opening into a disengaging chamber, statically pressurizing said chamber, diverting said gases angularly to the axis of said tube, through a port in the sidewall of said tube at a position upstream of said particle discharge opening, directing the diverted gases into a cyclone separator, the static pressure in said chamber being maintained at a level sufficiently higher than the pressure in said cyclone separator that said gas preferentially flows angularly from said tube through said port while said particles are carried by their higher momentum beyond said port and are discharged inertially through said opening.