US2382255A - Heat exchange apparatus - Google Patents

Description

Aug. 14, 1945. R. PYZEL HEAT EXCHANGE APPARATUS F iled Sept 29, 1941 INVENTOR ROBERT PYZEL Patented Aug. 14, 1945 HEAT EXCHANGE APPARATUS 7 Robert Pyzel, New York, N. Y., assignor to Uni- I versal Application larly advantageous as applied to tubular reactors oi the heat exchanger type and, more particularly, those wherein the reaction is conducted in the presence of a mass of solid granular contact material or catalyst. V

The features and advantages of the invention will be best understood with reference to the ac-v companying diagrammatic drawing which illustrates in sectional elevation a specific form of tubular. heat exchanger. type reactor embodying features of the invention. 1

Referring now to thedrawing,v the form of apparatus here illustrated comprises a substantially cylindrical outer metal shell I closed at its upper and lower ends by means of heads 2 and}, respectively, which in this particular instance are integral with or permanently secured to the cylindrical shell. Across the interior of the shell adjacent its opposite ends and permanently secured to the cylindrical wall thereof, tube sheets I, I, i and 1 are provided. The tube sheets are spaced from each other and from the heads 2 and 3 to provide header compartments 8 and 9 at the upper end or; the shell and header compartments I and II at the lower end of the shell. A nest of elongated tubular elements I2 is provided within shell I, each of which tubes extends continuously through the shell and protrudes from the heads 2 and 3 at its opposite ends. 1

Closure members of any convenient. form, such as caps I3, threaded to the protruding ends of the tubes are provided at the opposite ends of each-of the tubes I2 and are so constructed that they are readilyremovable from the tubes to give access to the interior of the latter. I A nozzle II which may serve either as an inlet or as an outlet connection is secured to shell I at the elevation of header compartment 8 and communicates with the latter. Another nozzle II, which serves as an outlet connection when nozzle. is employed as an inlet connection and vice versa, is secured to the shell at the elevation of header compartment II. and communicates with the latter. Another nozzle 16 which may serve as either an inlet or an outletconnectlon is secured to shell I at the level of header compartment; 8 and communicates therewith. Another nozzle which serves as an outlet con- Oil Products Company, Chicago, 111., a I corporation otDelaware September 29, 1941, Serial No. 412,743 1 Claim. (01. 257-224) I nection when nozzle it serves as an inle' connection and vice verse, is secured to the shell at bon conversion reaction, such 'quentlyremoved to restore catalyst.

the elevation of header compartment I0 and communicates therewith. Part of thetubes I: have openings 2| provided through their walls in that section of the tube which passes through header compartment 8 and II, so that communication is established throughthese tubes and headercompartments between nozzles I4 and ii. The remainderof the tubes II'have openings 2I provided through theirwalls in that section of the tube which passes through header compartments! and Il, so that communication is establlshed through these tubes and header compartments between nozzles l6 and II. I 7

Another nozzle I8 which serves as either an inlet or as an outlet connection is secured to shell I adjacent and beneath tube sheets and communicates with the space about the tubes within that portion of the'shell between the innermost tube sheets 5 d 6., Another nozz-e l8, which may serve as an outlet connection when n'ozzle I8 is employed as an inlet connection: and vice versa, is secured to shell I above and adjacent tube sheet 8 and alsofcommunicates with the space about the tubes'in thatportion oi the shell between the tube sheets! and 6. I

To. illustrate the utility and operation of the apparatus illustrated in the drawinajwe will assume that it is employed as a reactor in which tofconduct a catalytically promoted hydrocaras, for example, the dehydrogenation or butane. reaction. in common withmauy other hydrocarbon reactions, involves the deposition of. deleterious heavy materials of a carbonaceous or hydrocarbonaceous nature on the particles of catalytic material employed to promote the reaction and these deposits must be periodically and fre the activity. of the This is generally accomplished by deposits from the catalyst particles in a stream of oxygen containing gases. The catalyst in this particular instance comprises solid granular particles consisting essentially of I alumina and chromia andis disposed within tubes II, as indicated at 20. The reactants to be converted, which consist in this instance primarily of butanes, are heated by well known means, not 7 suitable for eil'ecting their substantialdehydrogenation upon. contact with the active catalyst and are supplied through nozzle II merit I and enter openings Ill into the burning the combustible illustrated, to a temperature to comparte of heavy hydrocarbonaceous products of the dehydrogenating reaction thereon, the stream of reactants to be converted is diverted from cornpartment 8 through nozzle I6-to compartment '9 and the dehydrogenating reaction is continued in the other tubular elements I2 which have openings adjacent their oppositeends communicating with compartments 9 and I0, the flow through these tubes being from compartment 9 through openings 2| downwardly through the catalyst beds within the tubes and from adjacent the lOWer end of thelatter through openings 2| into compartment I wherefrom the resulting fluid reactants and conversion products are discharged through nozzle I'I.

During use of the catalyst in one set of the tubes I2 for promoting the dehydrogenating reaction, the catalyst in the remaining tubes, which has become fouled or rendered relatively inactive by previous use, is regenerated. Thus the dehydrogenating reaction and regeneration of the catalyst take place simultaneously within the reactor, the zones of reaction and regeneration being periodically shifted between the two sets of tubes which communicate, respectively, with compartments 8 and II and with compartments 9 and I0. For example, during use of the catalyst within the tubes which establish communication between compartments 8 and II for promoting the dehydrogenating reaction, reactivating gases comprising, for example, a relatively small amount of air in a relatively large volume of inert gases, such as carbon dioxide, for example, is supplied through nozzle to compartment 9 and passes therefrom to compartment I0 through tubes which have openings 2| communicating with these two compartments. During passage reactor through nozzle I9, to a suitable heating zone, not illustrated, wherein the required additional heat is supplied thereto.

In case combustion gases are employed as the convective medium, said additional heating of the latter may be accomplished in a convenient mannerv by passing the gases being recirculated through a combustion zone wherein their temperature is increased by the addition of fresh increments of hotter combustion gases generated therein. In such cases a. portion of the combustion gas discharged from the reactor through nozzle I8 is released from the system to keep the quantity of gases flowing through the reactor substantially constant.

, When a liquid, such as molten salt, molten metal or the like is employed as the convective fluid, it may be passed, for example, through a tubular heating coil within a suitable fm'nace structure in order to supply the additional quantity of heat required thereto.

In case the heat available for transfer from the zone of reactivation to the zone of catalytic of the reactivating gases through the catalyst bed within these tubes, the combustible deleterious deposits are burned from the catalyst particlesand the resulting spent or partially spent reactivating gases are discharged from compartment I0 through nozzle I'I.

During the entire operation a convective fluid, such as, for example, combustion gases, molten salt, molten metal or any other suitable heat transfer medium, is circulated through the space around tubes I2 within shell I between the innermost tube sheets 5 and 6,. this material being supplied to the reactor through nozzle I9, for example, and discharged therefrom through nozzle I8.I Since the dehydrogenating reaction is endothermic and regeneration of the catalyst involves the liberation ofheatby combustion of the deleterious hydrocarbonaceous deposits, heat is transferred through the convective fluid from the zone of reactivation to the zone in which dehydrogenation is taking place.

When, as in this particular instance, the heat available from reactivation of the catalyst for transfer to the dehydrogenating zone is less than the heat of reaction required in the latter zone, additional heat may be supplied thereto through the medium of the convective fluid by passing the same, subsequent to its discharge through nozzle I8 and prior to its introduction into the reaction is more than that required .to accomplish the desired reaction, the excess heat may be extracted from the convective fluid by passing the same through a suitable'cooler or heat exchanger after it' is discharged from the reactor through nozzle I8 and before it is returned thereto through nozzle I9.

It is also possible, although rather unusual, that the heat available for transfer from the zone of reactivation to the catalytic reaction zone substantially equals the requirements of the latter. In such instances, that portion of the tubes I2 between the innermost tube sheets 5 and 6 may be immersed in a bath of liquid, such as molten salt, molten metal or the like, through which heat is readily transferred fromthe tubes in which reactivation of the catalyst is taking place to the tubes in which the conversion reaction is taking place, and except when desirable for maintaining substantially uniform temperatures throughout the reaction zone, little or no recirculation of the convective fluid will be required.

Altematively, in such instances, the tubes I2 for example, a packed Joint, may be provided in shell I intermediate its length between tube sheets 5 and 6 to accommodate diiferential expansion and contraction between the shell and the tubes.

It will be apparent to those familiar with the art that the construction illustrated and above described has numerous advantages over previous tubular heat exchangers and tubular heat exchanger type reactors. By extending the tubes through the tube sheets, header compartments and top and bottom heads of the reactor shell and securing them to the heads and tube sheets by welding, expanding or in any other convenient manner, they serve as stays for the heads and tube sheets, 1 thereby materially increasing their strength'and reducing their required thickness. This also eliminates the necessity for providing removable flanged heads, such as ordinaril required in apparatus of this class,for gaining acthe shell and forming in the end portions of the shell a first inlet compartment, a second inlet compartment, a first outlet compartment and a second outlet compartment, a, plurality of tubes extending through the shell and said compart- 5 merits and having their end portions outside the shell, closure means for the end portions of the tubes outside the shell, perforations in some of said tubes in the portions thereof disposed in said first inlet compartment and in said first outlet 10 compartment, and perforations in others of said tubes in the portions thereof disposed in said second inlet compartment and said second outlet compartment.

ROBERT PYzEL.

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