US2310244A - Control of cyclic operations - Google Patents

Description

Feb. 9, 1943. R. c. L AsslAT CONTROL op cYcLc OPERATIONS Filed oct. 13,' 1939 Patented Feb. 9, 1943 CONTROL oF CYCLIC OPERATIONS Raymond C. Lassiat, Swarthmore, Pa., assigner to iHoudry Process Corporation, Wilmington, Del., a corporation of Delaware Application october is, 1939, sei-iai Ne. 299,247

(Cl. 19a-52) 15 Claims.

The present invention relates to cyclic processes or concomitant reactions effected with the aid of contact masses of catalytic or other nature, i. e., operations wherein reactants are fed to a. contact mass for separate and distinct operating periods as for example, where diiferent reactants are admitted to the mass for alternating operations in which each of the reactants conditions and prepares the mass for the next operating period, as is typified by the use of a contact mass alternately to promote, enter into or in any way assist reactions which leave contaminating deposit or other substance thereon or therein and in regeneration to remove such deposit or otherwise restore the mass to active condition. It is directed particularly toward regulation of pressure and flow conditions within and through plants containing one or more bodies of contact material disposed in converters engaged in a cyclic operationV involving removal of reaction fluid from the mass and converters between operating periods in a purging step conducted at reduced or below operating pressure, for' example, at subatmospheric pressure after the manner disclosed in United States Patents 2,095,264 and 2,095,265, issued to A. E. Pew, Jr., and J. H. Pew, respectively, on October 12, 1937.

One object of the invention is to raise converter pressure from purging toward desired operating level by use of reaction uid normally occurring in the process while maintaining normal flow into and through the battery. Another object is so to select reaction fluid for this purpose in accordance with the nature of the succeeding operation that the efficiency of the cyclic process is improved. Another object is to maintain constant operating "conditions within the converter battery and equipment associated therewith. Still another object is to pro-vide apparatus for efciently and economically accomplishing the above objects. Other objects will be apparent from the detailed description which follows.

A concrete embodiment of the invention is disclosed in the accompanying drawing, in which:

Fig. 1 is a somewhat diagrammatic flow chart illustrating a typical application of the invention to a plant for transforming or otherwise treating hydrccarbons or their derivatives, ,one of the converters being shown partly in section to indicate a preferred interior arrangement; and

Fig. 2 is an enlarged elevational View illustrating a portion of one of the converters and pre- [erred conduit and valve arrangements, one valve being shown in section.

Referring to the drawing, and particularly to Fig. 1 there is shown a reaction zone comprising a battery of any suitable or desiredV number of converters 3, in each of which there is disposed suitable contact mass M, utilized alternately to transform or otherwise treat hydrocarbon starty ing materials and in regeneration to remove, for l,

example, by controlled combustion, carbonaceous or other deposit formed thereon and thereinas a result ofthe ori-stream reactions.4 In order to provide continuous flow of reactants to and products from the battery the reaction periods of individual converters are spaced 0r staggered so I that there is always at least one converter engaged in one of the alternating reactions. On stream reactants, for example, distillate or other hydrocarbons to be converted into high antiknock motor fuel are continuously forced at suitable pressure by pump 4 through heater 5 and feed main 6 to be admitted at desired or, reaction temperature to a selected one or plurality of conduits 'I and to the converter; or converters served thereby, while reaction products issue from the converter or converters into the corresponding conduits 8 andare led from the battery by products manifold 9 and line I0 to suitable further treatment which may include Vseparation in known manner of desired motor fuel from other products in fractionator I I, condenser I2 and separator I3, motor fuel and high boiling products` issuing by lines I 4 and I5, respectively, while condensed steam or the like leaves by line Ida and lower boiling hydrocarbons including incondensible gases discharge into line I6. A stream of reactants for the regeneration or combustion periods lsuch as air or other oxygen containing iiuid admitted to the system by line I'I is continuously forced by compressor I 8 through line I9, manifold 20 and the proper one or number of conduits 8 into the converter or converters engaged in the regeneration phase of the cycle while the fumes of the combustion reactions issue from the battery by the appropriate conduit or conduits 'l into manifold 2| selectively connected thereto and discharge line 22. During this phase of the cycle the contact mass undergoing regeneration is maintained at controlled combustion temperature, for example, below 1150 or 1100 F. If necessary or desirable, excess heat of combustion may be removed from the mass by passing regenerating medium in heat exchange relation with it. as for example, after the manner disclosed in U. S. Patents 2,042,469 issued to A. Joseph on June 2, 1936, and 2,042,468 issued to F E. J. Houdry on the same date and/or by use of an extraneous cooling fluid, for example, after the manner set forth in the aforesaid patent to A. Joseph or in U. S. Patent 2,078,947 issued May 4, i937 to E. J. Houdry and myself.

In order to effect process economies the hot regeneration fumes issuing from the converter battery are preferably utilized to supply process energy, one highly advantageous use of them being as indicated in U. S. Patent 2,167,655 issued August 1, 1939, to E. J. Houdry and R. S. Vose and in Fig. 1 of the drawing, to run a suitable motor such as turbine 23 disposed in line 22 to drive compressor I8. Prior to their admission to turbine 23, the regeneration fumes are preferably subjected to suitable treatment to adjust their energy content, temperature and/or composition. One such treatment is catalytic combustion of the CO content thereof at controlled temperature, as within the range of 700 to 1200* F. as set forth, for example, in the copending application of Eugene J. Houdry, Serial No. 266,010, filed April 4, 1939, now U. S. Patent 2,248,994. To this end, the fumes in line 22 may lie conducted through a catalytic combustion zone providing one or more suitable converters indicated at 2t containing a combustion promoter comprising, for example, copper or copper oxide.

After either one and preferably after both of the operating periods preparation of the converters for the next of the successive or alternating reactions involves removal or displacement of uid reactants and reaction products of the preceding reaction period which remain within the converter and adsorbed or absorbed by the contact mass. This is effected in a purging step, which, in the interests of rapidity and completeness of removal of reaction fluid, should be conducted at below operating or reaction pressure. For many commercial processes and especially in those employing porous or adsorptive contact masses, eicient purging is effected in a short time, usually within a few minutes, by application of substantial subatmospheric pressure to the converter, for example, after the manner set forth in the aforesaid U. S. Patents 2,095,264 and 2,095,265. To this end, a suitable degree of vacuum may be obtained by a pump, iet, or other desired equipment disposed in evacuation zone 25 and the vacuum applied for suitable periods and at proper intervals to individual converters in the battery through vacuum main 28 selectively connected to conduits 1. The rapidity and completeness of the vacuum purging step or steps may be still further improved by admitting to the converters simultaneously with application of vacuum thereto a regulated quantity of inert fluid, for example, steam admitted to the system by line 35 and conducted thence by line 4| to manifold 42 selectively connected to conduits 8. As set forth, in the copending application of John R. Bates, Serial No. 266,282, filed April 6, 1939, the rate of admission of the selected inert fluid to the evacuating converter is preferably so limited that it has little effect, if any, on the degree of vacuum pulled by the vacuum jet or the like. Admission of inert uid may be continued at the same or increased rate after the converter has been disconnected from the source of vacuum to assist in the next step of the cyclic process.

This next step, which completes preparation of the converter for the succeeding reaction period, is adjustment of converter pressure toward the level desired for that reaction. According to the invention, gaseous reaction fluid similar to that normally in contact with mass M during the ensuing reaction period and selected from reaction fluid normally occurring in the cyclic process is utilized for this purpose, thus in the one operation effecting adjustment of both converter pressure and of the nature of the iiuid content of the converters to at least approximate desired reaction conditions. By preference, the repressuring step is performed by admitting to the purged converters a regulated quantity of reactants and/or reaction products obtained or diverted from the continuous and main stream of the selected material entering or leaving the converter battery as by manifolds 6, 2|, 9 or 20. Usually only a small and sometimes a practically insignificant proportion of the main stream of selected reaction fluid need be so diverted and used. In many commercial processes for transforming or treating hydrocarbons, for example, 10% to 20% of the volume of the selected stream of hydrocarbon reactants or reaction products, regenerating medium or fumes simultaneously entering or leaving one or more converters in the battery is often more than ample to eect adjustment from subatmospheric to desired reaction pressure in two minutes or less. When the flow of inert fluid utilized to assist vacuum purging is continued after the vacuum is shut of! the quantity of reaction fluid needed to complete repressuring may be reduced by as much as 25%, 50% or more.

Although as indicated above, repressuring medium utilized before on-stream reaction periods may be hydrocarbon reactants, process and operating advantages are realized when more refractory hydrocarbons such as on-stream products iiowing through manifold 8 or a selected portion,'for example, a fractionated portion of this material, is utilized for this purpose. When reintroduced into contact with mass M reaction products have reduced tendency to form contaminating deposit on the latter and leave it in highly active condition for the on-stream period. Moreover, when the on-stream reactions effect general lowering of the boiling range of the charge as occurs in cracking, reforming, dehydrogenation, viscosity breaking and other processes, the reaction products are increased in volume and smaller proportionate quantities of them need be utilized for the pressure adjustment step. In some instances, and especially when contact mass M is highly active and has marked tendencies to promote formation of cols' and other deposit it -is preferred to use as repressuring medium only highly refractory portions of the reaction products. One source of highly refractory hydrocarbons valuable for this use is normally incondensable gases resulting from or remaining after transformation of the charge and issuing by line I6, for example, from gas separator I3 or other suitable absorbing, separating, fractionating or stabilizing equipment associated with fractionator I I. Such gases may be admitted to main or manifold ,2l selectively connected by valved branches to conduits 8 and thence to individual converters in the battery as desired or required therein. In order to provide for constant operating conditions and to avoid pressure and flow surges in such separating or other equipment, continuous small streams of the selected separated repressuring medium may be forced into surge tank 28 located in line 2l and released from the tank and line 21 as needed in the converter battery. Pressure adjustments before regeneration periods, contrary to those before oli-stream operations, are effected to best advantage with highly reactive fluid, ypreferably. with regenerating' medium. 'Ihis material in filling the converter penetrates into the catalyst to initiate the burning reactions under favorable-reaction conditions.

Actual diversion 'into a purged converter of the proper proportion'of the selected stream of reaction fluid entering or leaving the battery may, if desired, be effected by slowly or partially opening or cracking they main valve through which the converteris connected to manifold 6, 9, 20 o r 2|, as the' casev may be. Such a procedure, however, cannot often be relied upon for accurately limiting the rate at which repressuring medium is admitted to the converters to a value suiiicientlylow to avoid substantial power and pressure surges in the plant which tend to upset operating conditions. Accordingly, preferred arrangements of apparatusfor practicing the invention include equipment adapted for and capable of close control over the flow of repres- V suring medium. Oneadvantageous simple and mum flow through them to but a predeterminedl fraction, as or less, of the volume of the mainA stream'of reaction fluid from whichthe repressuring gas is dlverted. VThen, repressurlng of one of the converters is effected simply by opening to full extent valve 30 in the propery u branch or by-pass leading to the purged converter which meanwhile is 'otherwise sealed or blocked off from the stream of reaction fluid passing into, through and from the battery; after a predetermined time interval, say, a minute, or when the pressure' within the converter has reached desired or predetermined level, this valve is closed and suitable valve adjustments 4made for flowing reactants for the succeeding operation into and through the converter.

When the selected repressuring medium is reaction products diverted from the stream of the same leaving the battery, the valved by-passes and the additional valve operations incidental to their use may be dispensed with. Then, kthe main control valves, for example, the valves in conduits 8, may have placed in serieswith them suitable metering check valves indicated at 3l (Fig. 2) adapted to permit full stream discharge into products manifold 9 but only metered yfractional flow lin the reversev direction. A indicated in Fig. 2, one arrangement for doing this is to and turbine 23, are often-eliminated. In some instances, however, more satisfactory plantoperation results when such flow variations are corrected by addition of suitable fluid in regulated and compensating quantity to streams of're'actionfluid entering or traversing plant-equipment in response tov diversion 'of vreaction fluid for pressure adjustment.. For example, substantially constant. iiow into fractionator Il may be n iai'n-` tained by adding -to the hydrocarbon products flowing through line I0 controlled quantities of diluent hydrocarbons or inert fluid'supplied'to line 3B in response v'to changes in 4flow through line |ll.- One manner of regulating the time' and "i quantity Aof admission ofthe addedjiuid is to' employ a motor. valve.33 in line 34'- suitably con-f' nected-to iiow meter 39 disposed ln-linelll' (for. example, by electrical circuits diagrammatically..-.

indicated by broken lines) to function in' response.

to impulses generated-in flow"mete'r 39 with L' changes in iiow through line Il).v Likewise, con# stant ow of gases into turbine 23 may be reali ized by periodically admitting to thefumes'traversing line 22, preferably before combustion z one 24, a controlled or metered quantity' of steam vor other desired fluid supplied v'by' line 35, forfexf 1 ample, by use of motor valve 40 inV line 35 elecr v trically connected to motor valves 30 in by-passes- 2 8 (asindicated by the broken lines) tooperte in response to -opening and closing of any on'efr of the latter, either simultaneously or after a., suitable time interval as by use of time dela .y` v

relays. Hydraulic connections between motor f .valve 38 and flow meter 39 or between motor 'valves 30 and di) may be used inplace of'the electrically operated systems indicated. It isito lbe understood, however, that it is not necessary to successful practice -of this aspect of the invention that control over the'adm'issio'i-i' of compensating quantities of diluent or other'iluid to reactionv products leaving the reaction zone be 4made directly in response to flow n I changes or in response to the operation of valves in the lines` for admitting the selected repressur-,- ing iiuid to the converters.

in any part ofthe system caused by diversion ofwirepressuringV medium into the converters may be ypredicted and any tendency of such changesto upset eliicient plant operation maybe anticipated and corrected simply by operation' of valves in the conduits supplying the compensating fluid at employe. butterfly 'check valve in lwhich the flap or gate 32 is provided with a metering port or oriilce 33 *of suitable size. Then, repressuring of a purged converter and placing it on stream may be effected by rst opening the main valve in conduit 8 and after the proper interval admitting normal on-stream ow to therepresf sured converter.

By limiting to a'predetermined-maximumthe Y proportionate quantity of reaction uuid which-is diverted from its normal path of 'flow into a converter for repressuring purposes, substantial flow and pressure surges uniting to interfere with eilicient and closely controlled operation of auxiliary plant equipment, such as fractionator Il timed intervals synchronized with 'admission -of one., i

repressuring medium into the converters. method of accomplishing this is to utilize motor valves in fthe lines containing repressuring medium and compensating iiuid and, if desired, in4 any other portion of the-plant andto control their operationfrom a central point byv use of a suitable timing device, as for example, a cycle I timer and actuating' Aor activating circuits ysuch as disclosed in the' copending application4 of Henry Thomas, John-M. Pearson and Edward J. Nopper, Serial No. 160,122, filed August 20,1937, now U. S. Patent 2,250,507. Admission of steam or other suitable fluid to the stream of regeneration fumes before they enter combustion zone 2 4 permits utilization ofthe heat generated and .stored -in the latter tocompensate'for tendency of the addedfluid to modify the tempcratureof the stream entering turbine 23. Tendency for ow and pressure surges to occur and the need for injecting yadditional fluid into streams entering 'auxiliary equipment in response to use of reaction fluid as repressuring On the contrary, f), duration and extent of flow 'and pressure changes medium may be minimized or even eliminated Ythis medium in auxiliary compressor 44 which forces it into surge or storage vessel 45, and then releasingcontrolled quantities of the stored regenerating medium through valve 46 and back into line I9. One simple and convenient method of effecting release of the stored fluid is in response to pressure changes in line I9, as for example by use of a suitable pressure controller -indicated at 41 operatively connected to valve 46 as by an electric or hydraulic circuit. Alternatively, storage vessel 45 may be selectively and directly connected to the purged or evacuated converters to deliver repressuring medium through a manifold, showing of which was omitted from the drawing for the sake of simplicity and clarity, but which may be similar to manii'old 21. Likewise, constant flow of reaction products into fractionator II may be maintained with little or no addition of diluent fluid to line I by use of a suitable storage vessel in a line containing on-stream reaction products such, for example, as surge tank 28 in gas line 21. Addition of selected 4and stored reaction fluid directly to the converters or to the stream of reactants entering the battery at the time a repressuring step is taking place automatically compensates at least partly for the tendency of flow and pressure surges to occur. In either event, the volume of reaction nuid utilized for the repressuring step is in excess of the average or normal iiow to and through the battery. This fluid is held in the converter battery during the pressure adjustment period and is released from it at normal rate and without upsetting normal flow conditions when the repressured mass is again placed in active operation by admission to it of the normal flow of reactants. When, as is typied by the use of surge tanks 45 and 28, the repressuring medium is obtained from a source so located that its admission to the converters minimizes or eliminates tendencies to cause flow and pressure surges, smooth and eiicient operation results when use of the repressuring medium is controlled from a cycle timer or other suitable timing device.

One cyclic operation for transforming higher boiling hydrocarbons, for example, distillation residues from petroleum oils into lower boiling products including high anti-knock motor fuel in a plant containing six converters as shown in the drawing and containing an active or actirated porous silicious catalyst, for example, is to employ an operating cycle of about 30 minutes' duration with on-stream and regeneration pericds of approximately 10 minutes each separated by 5 minute intervals, in each of which intervals vacuum purging and repressuring steps are conducted, and to stagger the operation of individual converters in the battery so that, within each 5 minutes one converter starts on-stream operation while another enters into a regeneration period, with the result that at any given time two converters are on-stream, two in regeneration and the remaining two undergoing purging or repressuring. In this operation the on-stream reactants at pressure of about 30 lbs. per square inch gauge may be heated to Vaporization temperature with the aid of about 10% by weight of steam and the resulting vapors and steam admitted to the battery and selectively to the converters which are on-stream at a rate of about 11A volumes of charge (liquid oil basis) per hour for each volume of catalyst contained in these converters while maintaining the catalyst at 820 to 900 F.; air compressed to about 45 lbs. per square inch gauge may be simultaneously admitted to the battery and selectively to two other converters in it at a rate of about 0.5 cubic feet per minute for each liter of catalyst contained therein while maintaining the catalyst at controlled temperature preferably below 1000 F. Using the above typical operating conditions and vacuum purging periods following both onstream and regeneration periods lin which the converter pressures are reduced to 10 to 12 inches of mercuryabsolute pressure, the pressure within regenerated and evacuated converters may be adjusted to on-stream level within a minute by diversion into them of somewhat less than 10%v by volume of the stream of transformed products leaving the battery and to regeneration level in a minute or less by diverting into them approximately 9% of the fiow of compressed air from the stream of air entering the battery. The above quantities of hydrocarbon products and air sufiice even when the converters contain large quantities of free space including perforated inlet and outlet conduits embedded in the 'contact mass as disclosed for example in U. S.

Patents 2,042,468 issued to E. J. Houdry on June 2, 1936, 2,095,266 to T. B. Prickett et al. on October 12, 1937, 2,094,601'to E. J. Houdry on October 5, 1937, and 2,078,950 to E. J. Houdry et al. on May 4, 1937, and somewhat diagrammatically indicated at t1 and t2 in converters 3 of Fig. 1 nf the drawing. The resulting periodic and momentary variation in flow of hydrocarbons to a fractionator and of regeneration fumes to a turbo-compressor unit such asindicated at 23 and I8 in Fig. l of the drawing is insufficient to interfere seriously with their normal and eiicient operation.

It is to be understood that the invention is by no means limited only to the use of six converters or to operating cycles or operating periods of the length indicated above, or to treatment or transf formation of higher boiling hydrocarbons. On the' contrary, it nds application in longer or shorter operating cycles involving fewer or a greater number of steps and the use of any desiredpumber of converters. Other specific proc esses in which the invention finds application include polymerization, alkylation, hydrogenation, dehydrogenation, refining, aromatization and selective oxidation of hydrocarbons and their derivatives effected with the aid of contact masses periodically subjected to treatment including purging to remove fiuid and/or other reaction products accumulated thereon and tending to interfere with their activity.

The invention in its various aspects effectively coordinates intermittent and continuous processes. It provides desired or required uniformity of flow and pressure conditions within the continuous processes while permitting periodic and independent adjustment to desired extent of either or both of these conditions in the intermittent operation. The use of fluid common to the associated processes for adjusting pressures in the intermittent operation avoids complication of the latter by injection into the reaction zone and into contact with catalytic or other mass l disposed therein of 'non-reactant repressuring medium under conditions adversely affecting desired properties of the mass. y Such use of selected reaction fluid, in addition, further improves the overall efficiency of the intermittent -process and simultaneously avoids periodic and uncontrolled dilution of products flowing from the latter operation to continuous treatment and momentary upset of thelatter caused by discharging slugsv ofextraneous repressuring medium from contact 'mass entering into active operation. Moreover, according to certain of its aspects, the invention provides for maintenance of substantially constant flow and pressure conditions without dilution, even to minor extent, of reaction fluid with extraneous material.

I claim 'as my invention:

l.' In chemical operations effected with the aid of contact material wherein a continuous stream of reaction fluid is-passed in to and through said material and through a treating zone for reaction products requiring substantially constant pressure and flowconditions, said material being divided into a plurality of separate masses subjected to reaction periods at superatmospheric pressure when reaction fluid lpasses therethrough and into said products treating zone interrupted by periods when reaction fluid is exhausted therefrom at subatmospheric pressure, the process steps of repressuring said masses after said exhaust periods and before `said reaction periods by admission thereto of reaction fluid diverted from said stream, and admitting a compensating quantity of fluid tosaid stream before it enters said products treating zone to avoid any adverse effect upon flow and pressure conditions of the latter. v

2. In chemical operations effected with the aid of contact material through which a continuous stream of reaction fluid is passed and which is followed and associated by communicating flow of said stream with a products treating zone requiring substantially constant flow andpre'ssure conditions, said material being divided into a plurality of separate masses eachof which is subjected to reaction periods at superatmospheric pressure when said stream is passed therethrough interrupted by exhaust periods when it is disconnected from said stream and treating zone and connected to a source of vacuum which removes reaction fluid therefrom, the process steps of repressuring said masses after said exhaust periods with reaction fluid obtained by diverting a small proportion of thev flow from said stream and admitting the diverted portion to said mass, and simultaneously feeding to said products treating zone in addition to the stream of products leaving said contact material a compensating quantity of extraneous fluid.

3. In fluid treating processes effected in a battery of reaction zones in each of which a separate mass of contact material in cyclic order undergoes reaction periods at superatmospheric pressure separated by -periods in which reaction fluid is exhausted from the mass at below reaction pressure, the steps. of continuously and at .substantially constant pressure and flow conditions preparing a stream of gaseous reactant fluid in a treating zone, continuously feeding a stream of reactants so prepared to and through said battery, sending a stream of gaseous products from the battery through a second treating zone at substantially constant pressure and flow condimasses after said exhaust `fluid diverted from the 75 tions, repressuring said periods with gaseous stream ilowingbetween said treating zones, and admitting a compensating 'quantity of gaseous uid to said last named stream to maintain substantially constant flow conditions in said second treating zone.

4. In chemical operations effected in a battery of reaction zones in which separate masses of contact material in cyclic order undergo reaction periods under superatmospheric pressure interrupted by exhaust periods under subatmospherlc pressure, the process steps of' continuouslyv feeding gaseous reactants to said battery in substantially constant volume and under substantially constant pressure, continuously sending gaseous reaction products from said battery to a treating zone requiring substantially constant pressure and flow conditions, repressuring said masses at the end of said exhaust periods with gaseous fluid selected from the group consisting of reactants and reaction products obtained from the stream of selected fluid traversing the battery, and simultaneously adding to the stream flowing between said battery and said treating zone a compensating quantity of gaseous fluid to maintain substantially constant pressurel and flow'conditions within the latter zone.

5. In chemical operations effected in a battery of reaction zones in which separate masses of contact material are` subjected in cyclic order to alternating reaction periods for treatment or actants for each of said reaction -periods at substantially constant pressure and flow conditions in a reactant treating zone to prepare them for the desired reaction. continuously feeding streams of the treated reactants to said masses, flowing each of the resulting streams of reaction products issuing from said masses through a products treating zone requiring substantially constant pressure and now conditions, exhausting reaction fluid from said masses between said alternating reaction periods at pressure substantially below that employed in the succeeding one of said periods, repressuring the exhausted masses with gaseous reaction fluid similar to the fluid in' contact with said masses during said succeeding period and obtained by diversion of a controlled quantity of such fluid Ifrom the stream thereof simultaneously flowing between the reactants treating zone and .products treating zone therefor, and in response to said diversion of fluid adding a compensating quantity of fluid to said last named stream to maintain substantially constant .pressure and flow conditions in the last named zone.

6. In chemical operations effected in a battery of reaction zones in which separate masses of contact material in cyclic order undergo reaction periods under superatmospheric pressure interrupted by exhaust periods at reduced pressure,

substantially constant volume and at substantially constant pressure, further treating products of the transforming reaction periods and of the reactivation periods, utilizing reactivatlng reactants to repressure said masses at the end of each exhaust period following a transforming reaction,

and utilizingproducts of transforming reactions for repressuringsaid masses at the end of each exhaust period following a reactivating reaction. 7. In controlling cyclic operations involving the use of a converter containing a contact mass for successive. and distinct operating periods conducted at predetermined pressure conditions and in each of which reactant fluid fed to the mass conditions it for use in the succeeding operating period by forming deposit on or in it or by removing such deposit, the steps comprising purging said converter of reaction fluid between operating periods while maintaining it at pressure below that of the succeeding period, then raising the pressure within the converter toward that of said succeeding period by admitting to it reaction fluid similar to that in contact with the mass during said succeeding period, utilizing reactants when the succeeding operation removes deposit from the mass and reaction products when it tends to form deposit, thereby simultaneously to effect pressure adjustment within the converter and to maintain the mass at a high level of efficiency.

8. In controlling cyclic operations involving the use of contact material disposed in a battery of reaction zones as a plurality of separate masses alternately in contact with reactant fluid which reduces the activity of the contact material and with reactant fluid which reactivates said material, the steps comprising continuously feeding said reactant fluids separately and under substantially constant pressure and flow conditions to said contact material, continuously feeding the resulting products to products treating zones requiring substantially constant flow and pressure conditions, separating the reaction periods of fluid is released from them at below reaction pressure, raising the pressure of the exhausted mass toward the level desired for the succeeding reaction periods by admitting thereto reaction fluid similar to that in contact with the mass during said succeeding reaction periods, utilizing reactants when they tend to reactivate the mass and reaction .products when the activity of the mass is reduced in said reaction period, and simultaneously increasing the quantity of fluid admitted to the system by substantially the amount utilized for repressuring thereby to maintain substantially constant pressure and flow conditions within said treating zone.

9. In forming hydrocarbon reaction products by contact operations followed by treatment of the resulting products to separate them into fractions including ordinarily gaseous material and involving use of a contact mass disposed in a battery of converters engaged in a cyclic process wherein the mass is alternately on-stream and receiving reactants and in regeneration to remove contaminating deposit resulting from the onstream reactions, and the operating periods of the converters in the battery are differently timed to provide continuous and substantially constant flow of said reactants to the battery and of the hydrocarbon products to the separating treatment, the process steps comprising applying vacuum to one of the converters following a regeneration period therein to assist ifi-purging regeneration fluid therefrom, then before again admitting on-stream reactants to the converter raising the pressure within it toward on-stream level by admitting to it hydrocarbon products diverted from the stream of the same flowing from the battery, and in response to diversion of hydrocarbon products into the purged converter adsaid masses by exhaust periods when reaction mitting to the stream of products undergoing iurther treatment a controlled quantity of said ordinarily gaseous material thereby to avoid flow and pressure surges through the treating zone.

l0. In controlling cyclic operations involving the use of a contact mass alternately on-stream to transform reactants which leave contaminating deposit thereon and in regeneration to remove such deposit, the contact mass being disposed in a battery of converters whose operating periods are differently timed to provide substantially uniform flow of oxygen containing regenerating medium to the battery, the steps comprising utilizing regeneration fumes issuing from the battery to supply motive power for forcing regenerating medium into the battery, yreducing the pressure within said converters after onstream periods therein to below regeneration level and purging them of on-stream reaction fluid at reduced pressure, then raising the pressure within the converters toward regeneration level by diverting a small percentage of regenerating medium from the stream of the same slmultaneously entering another converter in the battery and admitting the diverted fiuid to the purged converter, and admitting a compensating quantity oi' inert fluid to the stream of regeneration fumes entering the power producing equipment in response to said diversion ofA regenerating medium, thereby to maintain substantially constant power delivery and flow of regenerating medium to the battery.

11. In effecting fluid reactions involving the use of contactmaterial disposed in a battery of reaction zones for operating periods when reactant fluid is admitted thereto at superatmospheric pressure separated by periods in which reaction fluid is exhausted therefrom at subatmospheric pressure associated with a fluid treating step requiring substantially constant flow and pressure conditions, the steps comprising continuously flowing a stream of reaction fluid between said 'battery and said treating step, repressuring said contact material at the end of said exhaust step with reaction fluid obtained from said stream, diverting to storage a portion of the stream of treated fluid issuing from said treating step, and releasing stored treated fluid to said stream of reaction fluid in response to use of portions of the latter as repressuring medium whereby the desired substantially constant pressure and flow conditions in said treating step are maintained.

l2. In the contact treatment of fluids wherein a stream of reaction fluid is .passed successively through at least three treating stages, the second of said stages comprising passage of the stream selectively and for distinct reaction periods over separate masses of contact material disposed in a battery of Contact zones, and the rst and third stages being respectively preparation of feed for the second stage and treatment of the discharge from that stage, the process of feeding fluid to be treated to said first stage at substantially constant flow and pressure conditions, separating said reaction periods by exhaust .periods when reaction uid is exhausted from said contact masses at below reaction pressure, repressuring said masses after said exhaust periods and in preparation for said reaction periods with reaction fluid diverted from the stream flowing through said three treating stages, and admitting a compensating quantity of fluid to said last named stream-before it enters said prducts treatment zone to avoid any adverse effect -upon flow and pressure conditions of the latter.

13. In the contact treatment of fluids wherein a stream of reaction uid is passed successively through at least three treating stages, the second of said stages comprising passage of the stream selectively and for distinct reaction periods over separate masses of contact material disposed in a battery of contact zones, and the first and third stages being respectively preparation of feed for the secondstage and treatment of the discharge from that stage, the process of feeding fiuid to be treated to said rst stage at substantially constant flow and pressure conditions, separating said reaction periods by exhaust periods when reaction fluid is exhausted from said contact masses' at below reaction pressure, repressurlng said masses after said exhaust periods and in preparation for said reaction periods with reaction fluid diverted from the stream iiowing through said three treating stages, and maintaining substantialy constant pressure and ow conditions in said third stage by adding a compensating quantity of fluid to the system between said first and third stages.

14. In a plant for effecting cyclic operations, in combination, means providing a plurality 'of reaction chambers for containing contact mass, a

conduit system adapted and arranged continuously to flow reactants to and reaction products from said means but periodically and for separate and distinct operating periods through each of said chambers, said system including a supply manifold for reactants and a withdrawal manifold for reaction products,` each selectively connected t said reaction chambers, a treating unit connected to said withdrawal manifold, means operable at subatmospheric pressure for withdrawing reaction fluid from said chambers between operating periods therein selectively connected thereto, additional valved means adapted and arranged selectively to connect said system with said chambers and periodically to admit to said chambers between operating periods therein as repressuring mediiun a meteredquantity of reaction fluid, and a valved conduit operable in response to use of reaction iiuid as repressuring medium for periodically admitting a controlled quantity of fluid to said system, thereby to maintain substantially constant flow and pressure Vconditions within said treating unit.

15. In apparatus for effecting cyclic operations, in combination, means providing a plurality of separated reaction zones for containing contact mass, supply and withdrawal manifolds for re, actant and reaction products, respectively, selectively connected by valved branches to said zones, means including4 a' vacuum producing means selectively connected to each of said zones for reducing pressure therein and withdrawing reaction fluid therefrom between reactionperiods, and valve means associated with the valved branches interconnecting said zones and one of said manifolds adapted and arranged to permit full ow of reaction iiuid between said zones and manifolds in one ldirection but only fractional or partial flow in the other direction.

RAYMOND C. LASSIAT.

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