US2262427A - Apparatus for reactivating catalysts - Google Patents

Description

Nov. 11, 1941. G. E. LIEDHOLM APPARATUS FOR REACTIVATING- CATALYSTS Filed Oct. 30. 1940 \rrvzni'or: Gzorqc Edward Lizd holm Patented Nov..l1, 1941 s PATENT OFFICE APPARATUS, ron nnaorlva'rmo CATALYSTS George Edward Liedholm, Long'Beacli, Calif assignor to Shell Development Company, San Francisco, Calif., a corporation of-Delaware Application October 30, 1940, Serial No. 363,434

2 Claims.

, In my copending application, Serial No. 279,247, filed June 15, 1939, which issued December 17, 1940, as Patent 2,225,402, there is described an improved method whereby inorganic catalytic materials which have become catalytically inefllcient due .to the deposition thereon of carbonaceous or combustible materials may be more eiflciently and safely reactivated or regenerated. The present application, which is a continuationin-part of said copending application, relates 'in particular to an improved apparatus particularly adapted for effecting the periodic reactivation or regeneration of such catalytic materials according to the improved method of said copending application. J

An assembly of apparatus suitable for effecting reactivation or regeneration and compre- 26, pipe 21 and valve 28, a compressor 29, pipe 3|! and valve 3|, and a heater or heat exchanger hended in the scope of the present invention is illustrated diagrammatically in the attached drawing. Referring to the drawing, l and 2 rep- I resent chambers or converters containing beds of catalysts and enclosed in a suitable furnace or,

heating chamber 3. While two catalyst chambers are shown, it is to be understood that only one chamber may be used or any number of additional chambers may be supplied and connected in parallel. The chambers I and 2, as

shown, are provided with inlets 4 and 5 and out-v lets 5 and I from and to manifold pipes 8 and 9, respectively. These connections are for the introduction and removal of reactants and reaction products when employing the chambers alternately as reaction chambers and reactivation chambers. In such cases where the reactivation in situ is not possible or feasible and the chambers I and 2 are used solely for reactivating catalysts, these connections 4, 5, 5, I, 8 and 9 may be dispensed with. When reactivating the bottom or from either end, somewhat better results are obtained when the reactivating-gas is introduced at the top and withdrawn from the bottom of the catalyst bed. The chambers may be of any of the many known designs, the only requirement being that the reactivating gas shall pass through the catalyst mass. In order that the temperatures during reactivation may be known, the chambers are preferably equipped with temperature measuring means, such as thermocouples 24 and 25, which allow the temperatures at any position throughout the length of the catalyst beds to be measured.

7 The intake manifold l8 and exit manifold 23 are connected through a cooler or heat exchanger 82, to form. a cyclic system. An inlet 32, provided with a regulating valve 33 for the introduction of a controlled amount of oxygen or oxygen; containing gas, is connected in the circuit on the high pressure side of the compressor to pipe 30. An outlet for spent reactivating gas and flushing gas 34 is connected in the circuit on the low pressure side of the compressor to pipe 21 The outlet is preferably provided with an automatic valve 35 for maintaining a constant pressure in the circuit and a by-pass exit valve 36. A gas holder 31, preferably capable of holding sufficient inert gas at the operating pressure to flush the catalyst chamber or chambers both before and after recatalyst in situ it is usually advantageous to em- 1 ploy a plurality of chambers, one or more being on-stream while the other or others, out out of the reaction circuit by valves l0 and I2, or l2 and i3, are being reactivated.

The catalyst chambers are provided with inlets l4 and I5, provided with suitable valves l5 and I I1, connected to a manifold pipe I8, and outlets l3 and 20, provided with suitable valves 2| and 22, connected to a manifold pipe 23. These connections serve for the introduction and removal of reactivating gas to and from one or more of the chambers during reactivation periods. While the chambers may be in a vertical, horizontal or inclined position and while the reactivating gas or reactant may be introduced from. the top or that the reactivation of chamber l is being comactivation without being replenished, is connected across the circuit between pipes 30 and 21 by means of pipes 38 and 39 provided with valves 40 and M, respectively. Valve 40 is provided to regulate the passage of inert gas from the high pressure side of the system into the gas holder. 1

While valve 40 may be of any conventional type, a preferred valve is a. pressure regulated'valve such as a pilot-operated motor diaphragm valve. Valve 4| is provided to regulate the passage of inert gas from the gas holder intothe low pressure side of thesystem. Valve 4| is provided for introducing flushing gas into the circuit. The gas holder,3| may also, if desired, be provided with a. valved inlet 42 for initially filling the circuit with-inert gas, or for introducing special chemicals, "etc.

Kit is assumed, for the purpose of illustration,

pleted and reactor 2 has been processing, then the system functions approximately as follows. Valves 33 and 28 close and valves 36 and 4| open.

and the system, including reactor I, is purged of oxygen-containing gases by means of inert gas from gas holder 3'l,'flowing via pipe 89, valve 4|, pipe 21, compressor 29, pipe 38, valve Si. (or in lieu of valve 3!, pipe 44, valve 45, cooler 83, pipe 51, separator 45, and pipe 48), pipe 39, prehe'ater 82, pipe l8, valve I6, pipe it, reactor 8, pipe i9, valve 2i, pipe 23, cooler 26, pipe 27, and valved outlet 36. Valves it, 2!, i2 and i8 then close, and valves ll, 22, ill and ii open. This purges reactor 2 with inert gas from the gas holder 31 and puts reactor i back on stream. If the residual reactant is a liquid at the operating temperature, it may be allowed to drain; it may be removed bymeans of steam or a solvent, or the removal may be assisted by applying a vacuum at the outlet 36 while valve ii is nearly closed. After the catalyst chamber has been flushed with inert gas, valve 3-6 closes and valves 33 and 28 open. An oxygen-containing gas, such as air, is forced into the recycling gas via the inlet 32 and flow regulating device 33. The excess oxygen-free gas, instead of leaving the system via outlet 36, passes through the pressure regulated valve cc and line 38 to refill the gas holder. As soon as the gas holder is completely recharged, the excess inert gas passes out of the system via the pressure regulated valve 35. Upon completion of the primary reactivation, the gas being recycled rapidly increases in oxygen concentration due to the continued addition of. air.

- After the catalyst has been sufllciently reactivated, valves 33 and 28 close and valves 36 and 4| open. As soon as the reactor has been purged of oxygen-containing gases, valves l1 and 22 close, valves l2 and I3 open, and reactor 2 is again on stream while another catalyst chamber is being flushed and reactivated.

The preheater 82, which may be a separate heating unit, a heat interchanger, or built in as an integral part of the furnace 3, is preferably employed to preheat the reactivating gas prior to its entrance into the catalyst chamber. In general, the, gases are preferably preheated to a temperature sufllciently high to initiate the oxidation reaction. The optimum temperature of the reactivating gases entering 'the catalyst chamber may vary considerably depending upon the particular circumstances and may even vary during the progress of the reactivation.

Certain catalysts are very sensitive to water. In order to maintain the optimum eiliciency of catalysts of this type, it is found that the water content of thereactivating gas, as well as the reactants, should be maintained constant within a narrow preferred range of low concentrations. If ordinary air or other fairly wet gas is applied to reactivate catalysts of this type, it is found that the reactivated catalyst, upon being put back on stream, often requires a certain induction period before returning to its normal activity. By maintaining the water content of the reactivating gases at the optimum value for the particular catalyst, it is found that such induction periods are entirely eliminated and that the reactivated catalyst immediately assumes its normal activity upon being put back on stream.

Thus, according to a. preferred embodiment of the present process, the recycled reactivating gas passes through a suitable cooling device 43, of

any conventional design, -uch as a coil cooler, water cooler, radiator, heat exchanger or the like, via pipes 80, t6 and valve 45. When the cooler .is used, valve ti is preferably closed. The comtion is continuously fed to the manifold i8 via.

lines ed and sit and heater 82 while the condensed water is removed from the system via outlet 49.

In view of the description of the purpose and function of the various apparatus diagrammatically shown in the drawing, it will be apparent that many modifications of the preferred illustrated assembly are possible without departing from the spirit of the invention. For example, the inlet 32 may be placed in the circuit at any position from beyond the outlet to the gas holder, in the direction of flow, up to the catalyst bed; the cooler and separator may be placed beyond the air inlet, in the direction of flow; the outlet 36 may be placed on either side of the cooler 26; the cooler 26 and preheater 82 may be put in heat interchange relation; the inert reactivating gas may be stored at lower pressure and charged to the circuit by a compressor; the arrangement and type of the valves and control devices may be varied, etc. Pipe 36 is provided with a suitable valve 68 adapted to allow recycled gas from the high pressure side of the cycle-to pass into the gas holder 31. Although valve til may be of any suitable type such as a relief valve and check valve or even a hand-operated valve, it is preferably a pressure regulated valve such, in particular, as a pilot-operated motor diaphragm valve. The motor diaphragm valve, if this is employed, may be. connected to and operated by the high pressure side of the cycle in the usual manner. I have found, however, that considerable advantage may be gained by connecting the valve to and actuating it by the low pressure side of the cycle. Thus, the line Bl from the diaphragm mechanism is shown in the drawing leading to the low pressure side of the recycle system ahead of valve 28. By actuating valve 40 by the pressure on the intake side of the compressor rather than the exit side of the compressor, it is found that a considerable improvement in the uniformity of the flow rates may be realized. This is of distinct advantage since it simplifies the problem of controlling'the oxygen input via valve 33.

I claim as my invention:

1. In apparatus for the execution of catalytic conversions with the aid of regenerative contact masses, the regeneration system comprising a catalytic converter and a gas circulating means connected in a cyclic system and a gas storage vessel connected across said' cyclic system through a pressure actuated valve to the high pressure side of the cyclic system and through a valve to the low pressure side of said cyclic system.

2. Apparatus according to claim 1 wherein said sure in the low pressure side of the system.

GEORGE EDWARD LIEDHOLM.

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