DK143988B - FLUIDIZED CATALYTIC CRACKING PROCESS - Google Patents

Description

(19) DENMARK \ W

| p (12) SUBMISSION WRITING «1) 143988 B

DIRECTORATE OF THE PATENT AND TRADEMARKET SYSTEM

(21) Application No. 2181/72 (51) IntCI.8 C 10 0 11/18 (22) Filing Day 2 May 1972 (24) Running Day 2 May 1972 (41) Aim. available Nov. 4 1972 (44) Posted 9 Nov. 1981 (86) International Application No. - (86) International Filing Day - (85) Continuation Day - (62) Master Application No. -

(30) Priority J>. May 1971, 159 ^ 53 US

(71) Applicant UNIVERSAL OIL PRODUCTS COMPANY, Des Plaines, US.

(72) Invented Clarence George Gerhold, US.

(74) Associate Engineering Company Budde, Schou & Co.

(54) Fluidis is a catalytic cracking process.

The present invention relates to a fluidized catalytic cracking process wherein the activity of a catalyst mixture which comes into contact with a hydrocarbon feed mixture can be regulated to produce a desired product yield structure.

In cases where fluidized operation occurs,

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a vertical riser is turned to reduce excessive mixing of reaction products with unreacted and partially reacted feed mixture. In this way, the reaction is conducted at a further distance from equilibrium, so that catalyzed reactions occur faster and with greater efficiency.

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This type of operation in a conventional system results in a high rate of catalyst transfer between the reactor and the regenerator, especially if the reaction is to be carried out under high catalyst-oil conditions. A high catalyst circulation between the reactor and the regenerator is undesirable because large amounts of oxygen in the form of oxidized catalyst enter the reactor, diluting reaction products with hydrocarbon oxidation products. We have now found a way in which this interconnection between the catalyst traffic between the reactor and the regenerator and the ratio of catalyst to oil in the reactor can be broken. The solution consists in returning part of the catalyst separated from the reaction products directly to the reactor feed, while the rest of the catalyst removed from the reaction zone is sent the usual route to the regenerator.

Accordingly, the present invention relates to a fluidized catalytic cracking process of the above-mentioned type, which cracking process is characterized by the feature of claim 1.

The present process can be used by the petroleum industry for continuous fluidized catalytic cracking or catalytic dehydrogenation or any other type of fluidized catalytic process.

The drawing illustrates the essential features of the process of the present invention and includes a riser reaction zone 6, a regeneration zone 9, and a regenerated catalyst conduit 18, which conduit connects regenerator 9 to the riser reaction zone 6. A catalyst recycle line or reflux line 5 connects to a container 8 with the lower portion of the riser 6. The riser 6 is directly connected to the container 8, which is a cylindrical structure containing a fluidized mass 16 of a catalyst and a separator 12 separating hydrocarbons from the entrained catalyst. Practically catalyst-free hydrocarbons are discharged from the container 8 via a conduit 10. The separator 12 may be a cyclone with a reflux line 14 which returns entrained catalyst separated from hydrocarbon to the fluidized mass 16.

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Recycle line 5 contains a sliding valve 2 which controls the flow of recycle catalyst into riser 6 from the dense mass 16. On recycle line 5 is shown an optional stripping line 20 through which, if desired, a stripping stream can be directed upwardly to remove adsorbed hydrocarbons from the recycle catalyst before passing into the riser 6.

A conduit 7 connects the container 8 and the regenerator 9.

This conduit may contain a sliding valve 4 for controlling the flow of catalyst from the dense mass 16 into the container 8 of the regenerator 9. in zone 9 ·

The regeneration zone 9 contains a cyclone separation means 13 which separates entrained flue gas catalyst which is removed from the regenerator via a discharge line 11. Any catalyst separated from flue gas is recycled to a dense mass 17 in the regenerator 9 via a reflux line 15. The oxygen supply stream therein enabling an oxygen-containing gas to burn coke on the catalyst is not shown on the regenerator. The regenerated catalyst conduit 18 contains a sliding valve 3 for controlling the flow of regenerated catalyst to the riser reaction zone 6.

At the bottom of the riser 6 there is an approach 1 through which fresh feed and / or recyclable materials enter and come into contact with both regenerated and recycled catalyst. The feed is evaporated causing the catalyst to pass into the riser to be fluidized and passed through the riser into the container 8.

The riser 6 enters the reaction vessel 8 at its lower part, so that materials from the riser 6 pass through the dense mass 16. In some cases, residual current from the riser 6 can pass directly to a cyclone separation zone for immediate separation of hydrocarbon catalyst. In these cases, the riser would probably be located along the side of the reaction vessel 8 and pass into this vessel through its side and directly into a cyclone separator.

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In normal operation, feedstock enters via approach 1 and contacts regenerated catalyst from conduit 18 and recycled catalyst from conduit 5. The hot catalyst evaporates the feedstock and the entire mixture of feedstock and catalyst is fed through the riser into reaction vessel 8.

In some cases, the catalyst entering the riser will not be hot enough to evaporate the feedstock. In these cases, the flow of regenerated catalyst to the reaction zone may be increased to provide more hot regenerated catalyst for evaporation of the feedstock. Alternatively, the recycled catalyst may be preheated in a catalyst preheater before entering the riser 6.

Recycle line 5 and line 7 need not be separate lines. Only one conduit need to connect the container 8 to the riser provided that somewhere along this conduit is provided a conduit also connected to the regenerator. Other methods for recirculating the riser catalyst are also included, and the present invention is not limited to the manner in which this material is recycled to the riser.

As depicted, the entire apparatus may be in a single insulating container which may contain a heat control means for providing controlled temperatures at various parts in the overall process.

The fluidized catalytic processes by which the present invention can be advantageously employed include catalytic. dehydrogenation and catalytic cracking. Other catalytic processes may be included within the scope of the term "fluidized catalytic process".

The reaction conditions in the riser reaction zone for catalytic cracking include a temperature of from ca. 427 to approx.

621 ° C, preferably from ca. 482 to approx. 554 ° G, a gas velocity of approx. 2 to approx. 23 m / sec, preferably from 2.4 to 13.7 m / sec, a pressure of from approx. 1.5 to approx. 5 µl atm, preferably from ca. 2.0 to approx. 4.1 atm and a weight room rate or weight of hydrocarbons per per hour weight of catalyst retained in the riser of approx. 10 to approx. 300 * preferably from ca. 10 to approx. 150, and a weight ratio of catalyst to oil, based on catalyst and oil entering the riser, of approx. 4 to approx. 20, preferably from ca. 6 to approx. 12. Preferred catalysts include 5 149 * 98 zirconia, silica, silica-alumina and the crystalline aluminosilicate zeolites.

Reaction conditions for a catalytic dehydrogenation process generally include temperatures of from ca. 510 to approx. 704 ° C, preferably from ca. 566 to approx. 677 ° C, pressure from approx. atmospheric pressure to approx. 7.8 atm, preferably from ca. atmospheric pressure to approx. 2.7 atm. Catalyst: the oil ratio can vary from approx. 4 to approx. 40, preferably from ca. 6 to approx. JO, and weight room rates can vary from approx. 1 to approx. 50 * preferably from about 10 to approx. 30. Applicable catalysts, including chromium oxide and chromium oxide-alumina catalysts.

Catalyst: the oil ratio K / 0 in the riser reaction zone can be divided into a K / 0 based on fresh feed and a K / 0 based on combined feed entering the riser reaction zone. K / 0 is usually based on regenerated catalyst flow, but when using this process, K / 0 based on regenerated catalyst will be lower than the actual K / 0, since at least part of the catalyst in the riser reaction zone is not regenerated catalyst. Thus, the amount of catalyst introduced into the riser reaction zone can be changed by the amount of catalyst recycled into this zone and by the amount of regenerated catalyst fed into this zone.

The conduits conducting regenerated catalyst and recycled catalyst may each contain control valves so that the ratio of regenerated and recycled catalyst can be regulated.

The exact ratio of regenerated catalyst to recycled catalyst is a function of catalyst and feed material properties, desired products and apparatus limitations.

Large amounts of coke generally impair the catalyst activity. A refiner operating a fluidized catalytic cracking process may wish to produce more fuel oil in the winter months than in the summer. Larger quantities of coke on the catalyst reduce gasoline production, so the refiner has an easy way to switch its production from gasoline to fuel oil. The refiner can operate his plant in the summer months with little or no catalyst recycling and in the winter months operate it from approx. 5 to approx.

95% recycled catalyst. As used herein, "5% recycled catalyst" means that $ 5 of the catalyst entering the stirrer is recycled and 95 $ is regenerated.

Continuous addition of both recycled and regenerated catalyst to the riser is preferred, although intermittent addition of recycled catalyst may be advantageous in some cases.

If a refiner operates his unit with less than approx. 5 $ recycled catalyst, there is only a very minor change in operation, and only a few, if any, of the benefits provided by the process in question would be observed. Operation with excess catalyst recycling can result in extremely large amounts of pollutants on the catalyst and can also adversely affect the heat balance of the process. Accordingly, from ca. 5 to approx. 95 $ of the catalyst is recycled to obtain the advantages of the present invention, although the range from about 25 to approx. $ 75 recycling is far preferable.

When converting existing fluidized catalytic cracking units to use the method of the present invention, a narrower range, from approx. 50 to approx. $ 50 recycling, optimal, although the aforementioned wider areas can also be used. Heat from the regenerated catalyst covers the heat demand of the process, from approx. 50 to approx. $ 70 of catalyst entering the riser should be hot, regenerated catalyst for optimum performance. In new units with alternative means for supplying heat to the process, greater leeway is possible in determining the amount of catalyst to be recycled.

The putty materials may vary depending on the operation taking place. In fluidized catalytic cracking, a gas oil feed material is usually used. Part of the product may also be recycled to the riser reaction zone. The recycle material may be a heavy cycle oil, a light cycle oil, recycle gasoline or a naphtha recycle stream.

Feeding material for dehydrogenation operation can range from low molecular weight paraffins to paraffins having 50 carbon atoms or more. In some cases, dehydrogenation feed materials may be olefins or cycloparaffins having the same carbon range as indicated for the paraffin compounds.

The riser reaction zone may vary in dimensions, and preferably has a length-to-diameter ratio, L / D, of from ca.

2.5: 1 to approx. 100: 1 or greater. The area is preferably from approx.

4: 1 to approx. 15: 1, but this may vary depending on the operation taking place. The riser is typically vertical and opens either into a fluid-dense mass reaction zone or directly into a cyclone separation zone that immediately separates the effluent stream in catalyst and reaction products. If the riser opens directly into a cyclone, the eyclone may be placed inside a large reaction vessel which may contain a fluidized mass of catalyst.

Regeneration zones are well known in the art. Regenerators usually have a lower L / D than riser to reduce the surface fluid velocity to reduce catalyst drift, thereby enabling the use of low efficiency cyclone separators on the regenerator flue gas stream. The regenerator burns coke deposits from the catalyst before returning it to the riser zone as regenerated catalyst. The regenerator is typically vertical and has an air or oxygen supply at the bottom. The oxygen burns carbon dioxide coke, resulting in the removal of carbon dioxide from the regenerator in the form of flue gas. Catalyst removed from the regenerator contains less than 0.1% by weight of coke, in some cases less than 0.01% by weight of coke. Recycled catalyst contains a higher concentration of coke.

The catalyst and hydrocarbon mixture leaving the riser reaction zone passes into a separator separating solid catalyst from hydrocarbon. The riser may enter directly into a cyclone disposed within a container or it may enter a reaction vessel (as shown in the drawing) and pass through a fluidized dense mass of catalyst before entering a separator. The term "separator" includes eyclones and also other apparatus designs that separate solid catalyst from hydrocarbon streams.

After separation from reaction products and unreacted feed, the catalyst can be divided into two streams, one of which is a recycle stream. The recycle catalyst is returned to the riser while the remaining catalyst is fed into the regenerator. To reduce yield losses, the catalyst is stripped prior to regeneration by passing a stripping stream, usually an inert gas or water vapor, through the catalyst countercurrently to stripping reaction products from the catalyst before entering the regenerator. It may be desirable to partially evaporate the recycle catalyst before entering the riser 8 to remove adsorbed hydrocarbons or feed material from the recycled catalyst. To eliminate excessive coke formation on the catalyst, this is done by rinsing off adsorbed hydrocarbons from the catalyst.

Stripping is usually carried out in a reflux line or other apparatus where contact between a stripping stream and catalyst may occur. The design of peelers is well known in the art.

A preferred embodiment of the present process consists in a fluidized catalytic process in which a feed stream, regenerated catalyst and recycled catalyst passes through a reaction zone, a portion of the catalyst is withdrawn from the reaction zone into a regeneration zone, and a portion of the catalyst is withdrawn from the reaction zone. to the reaction zone as recycled catalyst without entering the regeneration zone.

Claims (2)

143988 9 A fluidized catalytic cracking process wherein the activity of a catalyst mixture contacting a hydrocarbon feed mixture can be regulated to produce a desired product yield structure, characterized in that it comprises the steps of: (a) contacting a hydrocarbon feed stream in a riser reaction zone; catalyst mixture comprising a fresh, regenerated catalyst stream from a regeneration zone and a separate, recycled stream of spent catalyst taken from a spent catalyst stripping zone, (b) the feed stream and catalyst mixture are passed through mixing through the reaction zone by catalytic cracking, (c) the mixture is discharged into a separation zone under separation conditions to separate the catalyst from product components and any unreacted feed stream, (d) product and any unreacted feed stream are recovered, and spent catalyst is discharged from the separation zone into a spent catalyst stripping zone under stripping conditions to remove adsorbed and hydrocarbons present therefrom to form stripped, spent catalyst containing coke, (e) a first portion of stripped spent carbon is conducted from the stripping zone into a regeneration zone maintained under oxidation conditions and wherein coke is oxidized from the catalyst to produce fresh, regenerated catalyst, (f) freshly regenerated catalyst is conducted from the regeneration zone to the riser in step (a), and (g) simultaneously another portion of stripped, spent catalyst is directed from the stripping zone to the riser