DE1062858B - Process for the catalytic cracking of hydrocarbon oils - Google Patents

Description

GERMAN

The invention relates to a method for the catalytic cracking of hydrocarbon oils using a fluidized catalyst.

In the German patent specification 952 923 a method and device for catalytic cleavage of hydrocarbon oils using a fluidized catalyst described in Circulation through a reaction zone, a horizontal stripping zone located in the same container and through a regeneration tank is passed, with the gases and vapors coming from the stripping zone the coming from the reaction zone are combined and the fluidized catalyst layers in the reaction zone and the stripping zone are separated by a wall extending over the greatest height extends the catalyst layer in the reaction zone, and wherein the catalyst in disperse phase from the Reaction zone with the aid of steam or another gaseous stripping agent via an or several risers are passed into the stripping zone, whereupon the stripped catalyst is removed from the stripping zone flows via a line equipped with a control valve to the regeneration tank.

The method described in the cited patent has the disadvantage that it is little in operation is agile. While a given device under certain conditions, e.g. B. a certain Amount of catalyst of a certain activity and a certain amount of charge, etc., probably completely may work satisfactorily, it is not always possible under changed conditions, e.g. B. a reduced catalyst activity, an aged catalyst, as well as other loading best yield to work. In particular, the range of variation for the amount of catalyst is quite narrow, down by the fact that the amount of steam necessary for transport through the riser pipes that connect the reaction zone and the stripping zone becomes too large, since only a small one Amount of catalyst located in the reaction zone, and upwards by the fact that the increased catalyst level makes it necessary to close one or more riser pipes in the reaction vessel, a measure which may cause the stripping efficiency to be lowered.

The object of the present invention is to provide a modification or an improvement in the method described in German patent specification 952 923 with it one obtains greater mobility in the operation of the device and, in particular, a greater range of variation is made possible in terms of the amount of catalyst in the reaction zone.

An object of the present invention is to provide a method of catalytic cleavage Ver
of hydrocarbon oils

Addendum to patent 952 923

Applicant:
NV De Bataafsche Petroleum
Maatschappij, DenHaag

Representative: Dr.-Ing. F. Wuesthoff, Dipl.-Ing. G. Pulse
and Dipl.-Chem. Dr. rer. nat. Ε. Mr. ν. Bad luck man,
Patent Attorneys, Munich 9, Schweigerstr. 2

Claimed priority:
Great Britain July 30, 1957 and June 25, 1958

Keith Owen, Hooten, Cheshire (UK),
and Karel Swart, The Hague,
have been named as inventors

drive for the catalytic cracking of hydrocarbon oils using a fluidized catalyst to provide, as claimed in the main claim of German patent specification 952 923, with the top level of the catalyst layer in the stripping zone above the top of the riser tubes is maintained at a height that is from the upper level of the catalyst layer in the reaction vessel differs by a difference in height, which for a given catalyst circulation rate depends on the amount of steam or other gaseous stripping agent that is in the risers is introduced and which is consequently made with the help of the

909 580/380

Control valve located in the line through which the catalyst is removed from the stripping zone flows to the regeneration tank.

The fundamental difference between the method of the present invention and that in German Patent 952 923 described method can be seen in the fact that the catalyst layer the upper ends of the riser pipes were washed over in the stripping zone. It was found that you actually did A sufficient separation of the catalyst from the steam is achieved when working under these conditions works and one has the advantage that at a given catalyst - circulation rate the amount of steam necessary to transport the catalyst through the riser pipes compared to the difference in the and does not depend on the upper level of the catalyst layer in the reaction zone and in the stripping zone solely from the upper level of the catalyst layer in the reaction zone, as in the case of the German one The method described in patent specification 952 923 is the case. Because of this, make a change the level of the catalyst layer in the reaction zone does not show the corresponding changes the amount of steam introduced into the risers or the number of risers used necessary, as described in the German patent specification. Now there is only a corresponding one Correction of the upper level of the catalyst layer in the stripping zone is necessary, where appropriate the amount of steam and the number of risers need not be changed. This setting of the upper level of the catalyst layer in the stripping zone can be easily adjusted by a temporary Changing the rate of removal of the catalyst from the stripping zone with the aid of the Allow control valve in the standpipe that leads to the regeneration tank.

Due to the invention, it is possible to increase the amount of catalyst beyond the level that represents the maximum for satisfactory operation with the ends of the stripper risers facing each other located above the surface of the catalyst layer in the stripping zone.

Furthermore, in a given device, the stripping risers can be made shorter than in FIG the device that is used on the basis of patent specification 952 923, since it is no longer necessary is, the upper ends of the stripper risers above the surface of the catalyst layer in the To keep the stripping zone. The shortening of the riser pipes enables the minimum amount of catalyst to be increased decrease compared to the amount that is used when using the device for a Method according to patent specification 952 923 works. The entire range of catalyst loading that is used in the device, so it is expanded upwards and downwards when you click on Reason of the present invention, as well as works in accordance with patent specification 952,923.

As in the device according to the cited patent, the riser pipes can through that the catalyst is transported into the stripping zone can be constructed in various ways.

Any inert, gaseous or vaporous agent can be used as the stripping agent; in practice generally steam is used.

If necessary, one can meet devices for increased mobility in operation that one Can introduce steam into each riser at more than one level.

The device and the method based on the invention will now be based on the drawing on a Example will be explained in more detail.

The drawing shows a cross section of the device.

The apparatus is essentially the same as that described in FIG. 1 of the '952,923 patent is, except that the tops of the risers through which the catalyst is removed from the reaction zone is guided into the stripping zone, below the normal upper edge of the catalyst layer are within the stripping zone.

As shown in the drawing, the device is composed of a reaction vessel 1 which is divided into a reaction zone 3 and a stripping zone 4 by a vertical wall 2, which runs in the form of a chord through the horizontal cross section of the reaction vessel. The wall 2 is sufficiently high to reach above the highest level at which the swirling catalyst layer is maintained in the reaction zone 3 . The vapor spaces above the catalyst layers in the reaction zone 3 and the stripping zone 4 are connected to one another above the upper edge of the wall 2 .

The bottom of the reaction vessel 1 is provided with a line 5 for supplying the oil to be split and the catalyst and also with a distribution grate 6 which extends over the cross section of the reaction zone 3. Fission products, together with vapors from the stripping zone 4, are discharged through the line 8 to a fractionation tower (not shown) via the cyclone 7 for the separation of entrained catalyst particles, which in turn are returned to the catalyst layer in the reaction zone 3 .

For stripping, a number of riser pipes 9 are built into the stripping zone 4 , these extending upwards into the fluidized catalyst layer in the stripping zone 4 , their upper ends being below the upper edge of the catalyst layer, namely below the level of the mirror, which is in the Operation with large amounts of catalyst stops. Four risers are provided, the two centrally located ones having a larger diameter than the other two.

All risers 9 are connected to the fluidized catalyst layer in the reaction zone 3 via standpipes 10 , and they are provided at the lower part with a device 11 which contains a valve 12 for introducing steam in the upward direction into the riser 9 , while in a baffle plate 13 is provided a short distance above the upper end of each riser pipe 9. The catalyst is transported from the reaction zone 3 during operation via the standpipes 10 to the catalyst layer in the stripping zone 4 with the aid of the steam blown into the bottom of the riser pipes. During this transport, in which the catalyst flows through the riser pipes in a disperse phase and the residence time in these riser pipes is very short, e.g. B. is only a few seconds, the entrained and adsorbed evaporable hydrocarbons that are present in the catalyst mass, are largely separated from this again. The catalyst particles freed in this way, which collide with the baffle plates 13 after leaving the riser pipes 9 , fall back into the catalyst layer in the stripping zone 4 due to their weight. During the relatively long stay in this

Layer becomes the non-evaporable and the remaining evaporable still present in the catalyst Hydrocarbons split to a considerable extent. In the bottom of this layer will be Water vapor or another inert gaseous medium introduced through an inlet not shown, to keep the bed in a fluidized state and to remove the vapors from the top of the bed.

The bottom of each standpipe 10 is equipped with a supply line 16 and a valve 17 through which steam or an inert gas can be blown upwardly into the standpipes so that the catalyst mass remains swirled in these pipes and thus prevents the Standpipes become clogged.

The stripped catalyst is led from the stripping zone 4 via the standpipe 14, which is provided with a control valve 15 , to the regeneration tank (not shown), in which the carbon deposits are burned off by the catalyst. The regenerated catalyst is then passed from the regeneration tank to line 5 , via which it is circulated to reaction zone 3 together with fresh feed. The rate of removal of the catalyst from the catalyst layer into the stripping zone 4 can be kept at any desired height with the aid of a control valve 15, which is expediently a slide valve. If, moreover, a change in the upper level of the catalyst layer in the stripping zone 3 without a permanent change in the circulation rate of the catalyst is desired, this can be achieved by temporarily adjusting the control valve 15 until the upper level of the catalyst layer has changed by the desired amount, whereupon the control valve is turned back to its original position.

The correction of the upper level of the catalyst layer in the stripping zone 4 with the aid of the control valve 15 is of some importance in processes which are carried out according to the present invention, since the speed of the passage of the catalyst through the riser pipes 9 from the difference of the upper level of the catalyst layers in both zones 3 and 4 , provided that all other factors, including the rate at which the steam flows into the risers, remain constant. In the device according to patent specification 952 923, on the other hand, this speed depended only on the upper level of the layer in the reaction zone 3 , again on the assumption that all other factors remain constant.

In the process according to the invention there is therefore a further factor which intervenes in the regulation of the flow rate of the catalyst to the stripping zone and which makes it possible to maintain a given inflow rate for the steam into the riser pipes, despite the changes in the upper level of the catalyst layer in the reaction zone 3, the z. B. be necessary due to the lowering of the activity of the catalyst during aging, since a corresponding change in the upper level of the catalyst layer in the stripping zone 4 makes changing the steam introduction speed or the entire cross section of the riser pipes completely unnecessary, as mentioned in patent specification 952 923 is. Should also the upper level of the layer in the reaction zone 3 remain constant and z. B. to improve stripping

If a change in the steam introduction rate becomes necessary, everything else can remain unchanged, provided that a suitable compensatory correction of the upper level of the layer in the stripping zone 4 is made with the aid of a temporary correction of the control valve 15 .

Similarly, a change in the rate of circulation of the catalyst from one zone can be observed make into the other without changing the

ίο other variables by simply adjusting the valve 15 until the upper level of the catalyst layer in the stripping zone has changed to an extent corresponding to the change in the circulation rate, whereupon the valve 15 is adjusted so that the new circulation rate is obtained receives.

On the basis of this additional control, which can be obtained by adjusting the upper level of the catalyst layer in the stripping zone, the device is much more adaptable in operation than the device according to patent specification 952 923. This is e.g. B. important for an oil refinery, the one Number of different loads processed. It enables the process conditions to be such to change as required by a particular feed and the particular activity of the catalyst, the activity of the catalyst varying both with its age and from one type to another can. The device also enables changes to the conditions, the stripping process, without having to worry about the conditions in the reaction zone or the rate of circulation of the catalyst must change.

Obviously, the present invention can be applied to other embodiments in the same way of devices for the catalytic cracking of hydrocarbon oils using a vortex Apply catalyst, with a stripping zone in the reaction vessel, like them

z. B. in the device of the patent specification 952 923 with reference to FIGS. 3 and 4 is described.

According to the invention, processes can be carried out in the systems described in the cited patent in a simple manner by raising the level of the catalyst layer in the stripping zone until the upper ends of the riser pipes 9 are submerged. In general, however, it is more expedient to shorten the riser pipes in order to obtain a greater range of variation with regard to the upper level of the catalyst layer, while at the same time keeping it sufficiently above the upper ends of the riser pipes. An existing device can easily be changed during a shutdown; a new system can be designed in this way from the outset.

Some process examples according to the present invention are compiled in the following Table I, in which the main operating data for three experiments using the same device are specified. In experiment A, the device according to patent specification 952 923 is operated in such a way that the tops of the risers from the top surface of the catalyst bed into the stripping zone protrude. Experiments B and C are in accordance with the present invention, where submerge the tops of the risers.

The catalyst charge in Run A was the largest possible operating amount according to the patent 952 923; in experiments B and C the operating amount was much larger.

Claims (1)

Table I. A.
K Iiτιγλιt-_R Ahn
JV UW C1 L ^- IVU 1 1 (JI B.
Mixed things
Venezuela crude oil C.
IVU W CiL XVUIHJJ. 3.020 3.030 3.070 365 355 345 499 500 497 8.5: 1 9.3: 1 9.3: 1 64.9 65.4 65.6 162 194 215 01 41 ΊΟ 17.7 19.5 17.0 3129 3900 3950 952 1225 1360 4081 5125 5310 3.8 4.3 5.0 5.48 7.01 7.92 4.87 7.01 7.92 5.63 5.63 5.63 0.18 0.22 0.20 8.7 8.9 8.7 feed Feeding speed, t / day Feed temperature ^{, 0 C} Reaction ^vessel temperature, 0 C Ratio of catalyst to oil in the reaction vessel .... Conversion to 205 ° C, final boiling point, percent by weight Amount of catalyst in the reaction vessel, t Amount of catalyst in the stripping zone, t Catalyst circulation rate, t / min. ... Steam supply into the riser pipes, kg / hour Steam supply to the stripping zone, kg / hour Total amount of steam, kg / hour Ratio of steam to catalystXlO ^s Height of the catalyst layer in the reaction vessel, m *) Height of the catalyst layer in the stripping zone, m *) .. Height of the scraper riser pipes, m *) Carrying away catalyst in the fractionation tower, t / day Yield of coke, percent by weight *) Measured from the grate. From experiments B and C it can be seen that the catalyst charge in the reaction vessel is 32 and 49 t respectively greater than the amount used in experiment A, which was considered to be the maximum in operation according to patent specification 952,923. The stripper 30 efficiency, reflected in the coke yield, is virtually unchanged; only a slight increase in the entrainment of catalyst particles can be observed. The feed is set on the basis of the new method a maximum limit 35 characterized in that one must maintain a sufficient separation space between the surface of the catalyst layer and the entrance of the cyclone. In this device, the minimum amount of catalyst was 143 t. By lowering the height 40 of the stretcher risers, as indicated in Table I, by about 60 to 182 cm, it is estimated that reaction space charges down to about 110 tons can be operated while maintaining a maximum charge of 200 to 220 tons will. Were z. If, for example, the riser pipes were shortened by 60 cm, the following operating data were obtained (see Table II) in the two experiments D and E. In experiment D the catalyst charge was slightly below the maximum, and the stripping risers were submerged. Experiment E was carried out analogously to patent specification 952 923 proceed with the catalyst charge being about the minimum charge possible. Table II feed Mixed crude oil from the middle east Mixed crude oil from the middle east Feeding speed, t / day Feed temperature ^{, 0 C} Reaction ^vessel temperature, 0 C Ratio of catalyst to oil in the reaction vessel Conversion to 205 ° C, final boiling point, percent by weight Amount of catalyst in the reaction vessel, t Amount of catalyst in the stripping zone, t Catalyst circulation rate, t / min Steam supply into the riser pipes, kg / hour Steam supply to the stripping zone, kg / hour Total amount of steam, kg / hour Ratio of steam to catalyst X IO ³ Height of the catalyst layer in the reaction vessel, m *) Height of the catalyst layer in the stripping zone, m *) Height of the scraper riser pipes, m *) Entrainment of catalyst into fractionation tower, t / day Yield of coke, percent by weight *) Measured from the grate. Claim: Process for the catalytic cracking of hydrocarbon oils according to patent 952 923, since 3.065
380
497
9.5: 1
65.6
190
39.5
20.2
5443
1151
6594
5.4
6.82
6.70
5.02
0.14
9.0 3.030
351
497
8.6
63.3
129
22.5
18.0
3775
1290
5065
4.6
3.96
3.65
5.02
0.13
8.7 characterized in that the upper level of the catalyst layer in the stripping zone is above of the upper end or ends of the riser pipes is held. 1 sheet of drawings © 909 580/380 7.59