DE2221618A1 - Catalytic fluidized bed process - Google Patents

Description

The invention relates to a catalytic fluidized bed or fluidized bed process with components in the reaction tails moving catalyst (fluidized catalytic process; hereinafter referred to as fluidized bed process), in which a feed « flow of reactants and regenerated catalyst from a regeneration zone in admixture into the inlet of a reaction zone are introduced, impurities are deposited on the catalyst during the reaction in the reaction zone and catalyst withdrawn from the reaction zone into the regeneration zone is passed, regenerated there and then returned to the inlet of the reaction zone »

When carrying out catalytic fluidized bed processes a vertical riser pipe or vessel is often used, excessive backmixing of reaction products with unreacted and partially reacted feedstock to prevent. In this way, the reaction is carried out at a greater distance from equilibrium, so that catalyzed reactions run faster and more effectively.

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- Such an operation results in conventional Systems result in a high rate of catalyst transfer between the reactor and the regenerator, especially when the reaction is taking place must be carried out at high catalyst / oil ratios. It has been found that high catalyst circulation between the reactor and the regenerator is disadvantageous, in particular because large amounts of oxygen, in the form of oxidized catalyst, get into the reactor and this leads to a dilution of the reaction products with hydrocarbon oxidation products. "The method of operation of the invention eliminates these and similar disadvantages and the unfavorable interdependence of the catalyst conversion between the reactor and the regenerator on the one hand and the catalyst / oil ratio in the reactor on the other eliminated. This is done by a very simple procedural measure, which is also the case with existing ones Investments can be carried out without difficulty. It the result is a simplified, very well controllable, failure-prone and economical operation. For this purpose, part of the catalyst separated from the reaction products is used directly to the reactor inlet and only the remainder of the catalyst withdrawn from the reaction zone in the normal way passed to the regenerator.

^r 'object of the invention is followed by a fluidized catalytic process in which a feed stream of the reactants and of regenerated catalyst from a regeneration zone in a mixture into the inlet of a reaction zone to be introduced, are deposited in the reaction in the reaction zone impurities on the catalyst and catalyst from the reaction zone withdrawn, passed into the regeneration zone, regenerated there and then returned to the inlet of the reaction zone, which is characterized in that part of the catalyst is removed from the reaction zone.

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draws and without regeneration directly to the inlet of the reaction zone returns.

The method has preferred applicability in. the oil industry for continuous catalytic vortex cracking and continuous catalytic dehydration. drieruirg or similar catalytic fluidized bed processes.

The method is described below using a preferred. , additional embodiment in connection with the attached drawing further illustrated. ■ "'... ·

The in the drawing aar explanation of the process The plant shown has a riser reaction zone 6, fine Regeneration zone 9 and an overhead line 18 for regenerated catalyst, which connects the regenerator 9 with the riser pipe * -. reaction zone 6 connects. A catalyst return line 5 / roughly in the form of a downpipe, connects a reaction vessel 8 with the lower section of the riser reaction zone 6. The riser reaction zone 6 opens directly into the reaction vessel. 8th; the latter is cylindrical in shape and houses a fluidized catalyst bed 16 and 'a separation device' 12, the hydrocarbons of initiation. Catalyst separates. the The essentially catalyst-free hydrocarbons that occur flow out of the reaction vessel 8 through a line 10. the Separating device 12 can consist of a cyclone separator with a dip tube 14 exist, the immersion tube carries dragged and - from the

Hydrogen carbon f en separated -factEtiysatdrteiiehen- z-u-fdem-We:

exposure bed 16 back. . . *

A slide valve is located in the return line 5 2, through which the flow of recycle catalyst from the. dense catalyst bed 16 la the riser 6 is controlled. At the Katälysatorreckfuhrleitung 5 can optionally a

Stripping line 20 be attached, through which, if desired, a stripping flow can be directed upwards, in order to remove adsorbed hydrocarbons from the recycle catalyst before entering the riser pipe 6.

A line 7 connects the reaction vessel S to the regenerator 9. This line can contain a slide valve 4, the catalyst flow from the dense catalyst bed 16 in the vessel. 8 to control the regenerator 9. One line 19 -Allows the introduction of a Aus'streifStroms in the line 7, if necessary, to remove adsorbed hydrocarbons to largely remove the catalyst in the regeneration zone 9 before the regeneration.

The regeneration zone 9 contains a cyclone separator 13, which separates the carried catalyst from the exhaust gas; the latter is through an outlet line 11 from the regenerator deducted. Catalyst separated from the exhaust gas is passed through a dip tube 15 into a sealed one located in the regenerator 9 Catalyst particle bed 17 recycled. Not shown on the regenerator is the oxidizing gas inlet through which an oxygen-containing Gas for burning coke is supplied from the catalyst. The transfer line 18 for the regenerated Catalyst includes a gate valve 3 for controlling the flow of regenerated catalyst to the riser reaction zone 6th

At the lower end of the riser pipe 6 is a

Inlet 1, through the fresh feed and / or recycle materials be fed; they then contact both regenerated and recycled catalyst. The loading evaporates in the process and this leads to the fact that the catalyst flowing into the riser pipe fluidizes and through the riser pipe into the Vessel 8 is carried upwards.

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The riser 6 opens into the lowermost section of the reaction vessel 8, so that the coming from the riser 6 Materials flow through the dense catalyst bed 16. In some cases, the discharge can be modified from the riser reaction zone 6 for the immediate separation of the catalyst from the hydrocarbons directly in a cyclone separation zone are fed. In such cases, the riser pipe can be shaped like a corner on a side wall of the reaction vessel 8, long and then through the side wall, into the vessel and directly to a cyclone separator »·

During normal operation, the feed enters through inlet 1 and then comes with regenerated Catalyst from line 18 and recycled catalyst from "line 5 in contact. The hot catalyst evaporates the feed and the entire mixture of feed and catalyst flows upward through the riser reaction zone 6 into the reaction vessel 8. In some cases it can go into the riser incoming catalyst will not be hot enough to vaporize the feed .. Then the flow of, regenerated Catalyst to the reaction zone can be increased to a larger one Provide amount of hot regenerated catalyst to evaporate the feed. Alternatively, the returned The catalyst is preheated in a catalyst preheater before it enters the riser pipe 6.

The catalyst return line 5 and the line 7 do not need to be in the form of separate lines. Only one line is needed, the reaction vessel 8 with the riser pipe 6, as long as a branch line is provided somewhere on this line that connects to the regenerator manufactures. Likewise, other methods of recycling catalyst to the riser can be used, and that

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Procedure is not in the special way in which the catalyst is returned to the riser.

The entire illustrated arrangement can and of course be contained in a single insulated container also heat control devices for bringing about certain temperatures included at certain points in the overall procedure.

Catalytic fluidized bed processes that can be improved by the method described here are in particular catalytic dehydrogenation and catalytic cracking. But there can also be other catalytic processes that fall under the term of the catalytic fluidized bed process, made more favorable by the process described.

Suitable reaction conditions in the riser reaction zone include temperatures in the case of catalytic cracking from about 427 to 621 ° C (800-1150 ° F), and preferably about 482 to 554 ° Ο (900-1030 ° F), gas velocities of about 1.8 to 23 m / sec (6 to 75 feet / sec) and preferably 2.4 to 13.7 m / sec (8 to 45 feet / sec), pressures from about 1.5 to 5.1 atir. (8 to 60 psig) and preferably about 2.0 to 4.1 atm (15-45 psig), and an hourly space velocity based on weight, i.e. weight units of hydrocarbons per hour and per weight unit of the catalyst in the riser pipe (WHSV), in the range of about 10 to 300 and preferably about 10 to 150, and a weight ratio of catalyst to Oil, based on the catalyst entering the riser and the oil entering the riser, from about 4 to 20 and preferably about 6 to 12. Preferred catalysts include zirconium oxide, silicon dioxide, silicon dioxide-aluminum oxide and the like crystalline aluminosilicate zeolites.

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Suitable -Reaktionsbedingungen for a catalytic Dehydrierverfahlren generally include temperatures of about 510 to 7O4 ° C (950-1300 ° F) and preferably about 566 to 677 ° C (1050 to 1250- ⁰ P) ₇ and pressures from about atmospheric pressure to 7, 8 atm (100 psig), preferably from about atmospheric pressure to about 2.7 atm (25 p.sig). The catalyst / oil ratio can be in the range of about 4 to 40, and preferably about 6 to 30 / the weight hourly space velocity can be maintained in the range of, about 1 to 50 and preferably about 10 to 30. Suitable Catalysts are in particular chromium oxide and chromium oxide-aluminum oxide catalysts.

The catalyst / oil ratio in the riser reaction zone can be broken down into a catalyst / oil * ratio, relating to the fresh batch, and a catalyst / oil ratio, which relates to the combined feed entering the riser reaction zone. The catalyst / oil ratio is generally referred to as regenerated catalyst flow; when applying the working method according to the invention this is related to regenerated catalyst The catalyst / oil ratio is naturally lower than the actual one Catalyst / oil ratio, since, at least part of the in the Risigrohrxeaktiönszohe "catalyst from not regenerated catalyst. The amount of catalyst flowing into the riser reaction zone can thus both by the amount of catalyst returned to the riser reaction zone as well as by the amount of regenerated introduced into the riser reaction zone Catalyst can be controlled.

The lines for the flow of regenerated catalyst and for the flow of recycled catalyst, as shown, each may have flow control devices; so that the ratio of regenerated to recycled catalyst sator can be controlled. "

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The exact ratio of regenerated catalyst to recycled catalyst used in the individual case depends of the catalyst and the properties of the feed, of the desired products and possible conditions of the System. . . ",.

High levels of coke generally reduce catalyst activity ο When performing a catalytic fluidized bed cracking process The wish often occurs, for example to produce more heating oil in the winter months than in summer. Higher coke levels on the catalytic converter lower gasoline production. The method of the invention thus opens up a procedural aspect very simple way to shift the production of gasoline towards heating oil and vice versa. To do this, the Plant only "during the summer months with comparatively less or without catalyst recycling and during the winter months with comparatively high catalyst recycling, about 5 to 95% of the catalyst being recycled. The designation "5% recycled catalyst" as used here, means that 5-I. of "the catalyst entering the riser. are returned directly and 95% have been regenerated.

Both recycled catalyst and regenerated catalyst are preferably fed in continuously xu of the riser reaction zone, but in some cases it can also be • Ine intermittent addition of recycled catalyst ' be appropriate,. ■

If the operation is carried out with less than about 1/2% of the catalyst recycled, there is only a very slight change in the operating sequence, so that the advantages that can be achieved by the method according to the invention are only achieved to a small extent. An operating passage with an excessively large Katalysatorrüekführung can tu high levels of the catalyst

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Contamination and adversely affect the Lead the heat balance of the process. Accordingly, should be general 5 to 95% of the catalyst can be recycled to ensure the benefits of the process explained, recycling is preferred in the range of about 25. to -75 ■% *

In the event of a conversion of existing catalytic Fluidized bed cracking systems on the working method .'der- Er-. · finding results in a slightly wider range with about 30 to 50% Repatriation 'optimal results based on previous experience, although the broader ranges given above can also be used. Heat from the regenerated catalyst, provides the required heat of the process and accordingly should be about 50 to 70% * of the catalyst entering the riser for "an optimal operation of hot regenerated , Catalyst are formed. In the case of newly built plants with alternative means of supplying heat to the process there is a somewhat greater leeway with regard to determining the amount of catalyst to be recycled.

The charges can vary considerably depending on the implementation carried out and the particular mode of operation subject. In catalytic fluidized bed cracking a gas oil feed is usually used “Part of the Product can also be recycled to the riser reaction zone v / earth. The return material can be a heavy cycle oil, a light cycle oil, a cycle gasoline or trade a circulatory naphtha "

Feeds for dehydration can range from low molecular weight paraffins to paraffins 30 or more Carbon atoms range. In some cases, feedings for the dehydrogenation from olefins or cycloparaffins in the same Carbon range as described above for the paraffinic Compounds have been specified, exist or contain these.

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- OK

The dimensions of the riser reaction zone can be different from case to case, preferably the ratio of length to diameter is in the range of approx. ^T a 2.5: 1 to 100: 1 or more. A range of about 4: 1 to 15: 1 is particularly preferred, but here too, depending on the operation carried out in the individual case, considerable changes are possible. The riser pipe is normally arranged vertically and it either opens into a reaction zone with fluidized! dense bed or .direkt in a cyclone - »separation zone, which immediately separates the effluent stream into catalyst and reaction products. If the riser pipe leads directly into a cyclone separator, the cyclone can be arranged within a larger reaction vessel, which also gin. Catalyst fluidized bed may contain "

Suitable regeneration zones are known. Regenerators usually have a lower ratio of length to diameter than riser pipes, in order to lower the medium empty space velocity and to reduce the entrainment of catalyst, so that comparatively low power cyclone separators can be used for the exhaust gas flow of the regenerator coke deposits are burned down from the catalyst before this catalyst is returned to the riser reaction zone as regenerated catalyst. Cor regenerator is normally vertical and has an air or oxygen inlet at the bottom. Oxygen burns coke to KahlendioKyd, Kohlsndio% yd from the: regenerator The catalyst discharged from a regenerator usually contains less than 0.1 percent by weight of biscuits and in some cases less than 0.01 percent by weight of biscuits. The recycled catalyst naturally has a higher Ko ksgshalt.

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■ - · χι

•. "■ The mixture of catalyst and hydrocarbon., .- the" leaves the -. riser reaction zone, flows into a separating, facility for. Separation of solid catalyst from 'the hydrocarbons. The riser pipe can lead directly into a cyclone separator located inside a vessel, or it can as shown in the drawing, mouth into a reaction vessel. so that the material emerging from the riser pipe through a fluidized dense catalyst bed flows before a separation "The'expression" "separating device" occurs in the separating device 'should include "cyclone separators and other facilities, which, to a separation of solid catalyst from Koh 1 en hydrogen streams are able to. ". ■ · ·. ·

. ■ - ■. After separation from the reaction products and unconverted feedstock fractions, the "catalyst" can be divided into two "streams" from the start, one of which represents the "catalyst recycle stream". The catalyst recycle stream v / is returned to the riser ¹ , while the remainder. »Is led into the catalyst regenerator to Verrin- ■ gerüng'von yield losses * is rinsed the catalyst useful before regeneration> By e.in- Abstreifstrom, in aligemeinen a Inertgas.oder water vapor in, Gegenström by the" catalyst · guided This means that the reaction products from "the ^1st Catalyst expelled before its entry into the regenerator ". It can also be expedient to at least partially rinse out the return catalyst before it enters the riser in order to remove adsorbed hydrocarbons or feed components from the directly returned catalyst. This eliminates an excessive Coke deposits on the catalyst, because the flushing of adsorbed hydrocarbons prevents too long contact with the catalyst.

The rinsing-can be done in a downpipe or an- '' " their device, the · an intimate contact of a .Rinse out stream

guaranteed with the catalyst. Suitable rinsing agents Stripping devices are known.

According to a preferred embodiment, the creates Invention thus a catalytic fluidized bed process in which a feed stream, regenerated catalyst and recycled By passing catalyst through a riser reaction zone, a portion of the catalyst is fed from the reaction zone a regeneration zone and part of the catalyst withdrawn from the reaction zone and without entering the Regeneration zone returned directly to the reaction zone will.

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Claims (7)

Claims 1. Catalytic fluidized bed process in which a feed stream of reactants and regenerated Catalyst from a regeneration zone in the mixture -in the The inlet of a reaction zone is introduced and, during the reaction in the reaction zone, impurities are deposited on the catalyst and catalyst are withdrawn from the reaction zone, passed into the regeneration zone, and regenerated there is then returned to the inlet of the reaction zone, characterized in that one Part of the catalyst from the reaction zone "withdraws and without Regeneration is returned directly to the inlet of the reaction zone. 2. The method according to claim!, Characterized in that that catalyst on which coke has been deposited as an impurity is returned directly to the inlet of the reaction zone. . · ■■ · ■ ' 3. The method according to claim 1 or 2, characterized in that that one can recycle part of the catalyst directly to the inlet of the reaction zone in a catalytic Fluidized bed cracking process carries out. 4. The method according to claim 1 or 2, characterized in that the direct recycling of part of the catalyst to the inlet of the reaction zone in a fluidized bed dehydrogenation process performs. 5. The method according to any one of claims 1-4, characterized in that the direct recycling of part of the 209848/1046 Catalyst in a reaction zone, the inlet of which from the lower Section of a riser reactor is formed, performs. 6. The method according to any one of claims 1-5, characterized characterized in that there is about 5 to 95% and preferably about 25 to 75% of the total entering the inlet of the reaction zone Catalyst, recirculated directly from the reaction zone without regeneration. 7. The method according to claim 6, characterized in that about 30 to 50% of the total in the inlet of the reaction zone returning catalyst directly from the reaction zone without regeneration. 209848/1046