US2348512A - Heating of fluids - Google Patents

Description

May 1944. M. w. BARNES 2,348,512

HEATING OF FLUIDS Filed Jan. 26, 1942 2 Sheets-Sheet 1 INVENTOR MARION w. BARNES BY FIG. I ATTORNEY May. 9, 1944. M, w BARVNES 2,348,512

HEATING OF FLUIDS Filed Jan. 26, 1942 INVENTOR MARION w. BARNES ATTORNEY Patented May 9, 1944 ammo or ramps Marion W. Barnes, Chicago, 111., assignor to Unlversal Oil Products Company,

corporation of Delaware application January 28, 1942, Serial No. 428,241 1 Claim. (Cl. 122-250) This is a continuation-in-part of my copend-- ing application Serial Number 236,681, flled October 24, 1938.

The invention relates to the heating of fluids and more particularly to a heater in which separate streams of fluid, either in liquid, vaporous or'mixed phase, may be quickly heated to the small quantities of fluid are to be heated to moderate temperature, such as for instance in the heating of normally gaseous hydrocarbon charging stock for a catalytic polymerization process,

to form gasoline fractions of high antiknock value from oleflnic components thereof. My invention' may also be advantageously employed as a reboiler heater for supplying heat to'the various columns employed in fractionating and gas concentration systems and the like.

In designing heaters for the class of service contemplated by the invention, pressure drop is an important item to be considered. By employing a heater of the improved type provided by the invention a considerable reduction in pressure drop is obtained as compared with that encountered in conventional heaters now employed for such service. In processes wherein pumps, compressors or blowers are required to force the fluids to be treated through the heater,

the size of such equipment, and therefore the cost of-installatio:i, as welloperationand maintenance, is directly dependent upon the re-" sistance encountered by the fluids in traversing the heater. In previous heaters this resistance to the flow of fluids through the heater has been governed by the size of the fluid conduit. It' is well known that small size heating conduits give better rates of heating, other conditions being comparable, than larger diameter tubes, because of their greater heating surface per unit volume. Also, more uniform heating of the entire stream is obtained throughout the cross-sectional area of the conduit with smaller tubes.

. The features of my invention provide a compact heater which is simple to construct and at the same time offers the advantage of emcient and rapid heating of fluids to the desired temperature without excessive pressure drop by utilizing relatively small fluid conduits disposed in parallel flowarrangement.

The accompanying diagrammatic drawings Figure 1 of the drawings is an elevational view, shown principally in cross-section, of one form of heater provided by the invention.

Figure 2 is a ems-sectional view of the same heater taken along a plane indicated by line 2-2 in Figure 1. v

I Figure 3 is an elevational view, shown partially in section, of a modified form of the invention. I

Referring to Figures 1 and 2, the main furnace structure comprises an outer wall I, a roof 2 and a floor I. The walls, roof and floor are constructed of suitable refractory material which may, for example, be flre-brick shapes or one of the several types of materials which are placed in semi-solid or plastic form and upon hardening or setting pomess good refractory characteristics. A suitable metallic shell or housing 4 encases the refractory walls, roof and floor of the urnace and this housing extends, as indicated by 5, beneath floor 3 and is anchored to a suitable foundation 6, a space I being provided between floor s and the foundation. The upper portion of housing 4 converges to and supports a stack 8, which is provided with a suitable damper I.

The fluid conduit through which the fluid undergoing treatment is passed comprises a tubular coil ll having several helical turns and a plurality of flat spiral coils ll disposed above the coil II. The coil I0 is a single helix and the fluid undergoing treatment passes through the turns of the helix in series. The coils it .comprise a plurality of superimposed flat spiral coils arranged for. the parallel flow therethrough of two separate streams of fluid of substantially equal volume. The coils H and Ill are interconnected inseries. V

The central portion of the heater, within which coil II- is disposed, comprises a combustion and heating zone-l2 and the tubular turns of the coil are located relatively close to the circular wall 4 of the heater, leaving an unobstructed space within the coil and heater for the emcient combustion of fuel and for the upward passage of flames and hot gases resulting from such combustion.

Theflatspiralcoils'll aredisposedwithinthe' upper portion of the heater directly above the combustion and heating zone I! and the tubular I members of these coils are located within the direct path oftravel of hot combustion gases 4 from zone l2, being intimately contacted with the gases during eof the latter combustion zone I! to the stack 8.

A gas burner I4 which, in the case here illustrated, is supplied with a gaseous fuel through from :the

line I! andvalve leis provided within space 1.,

It is entirely within the scope of the invention I to employ burners of other types than that shown Regulated quantities of air for combustion are admitted to the space I through-the opening I! in-shell i, controlsoi this air being obtained by movement 01' the sliding damper It. In the burner here shown, a portion of the air for combustion is admitted thereto throughv a suitable mixing device It, and the combustible mixture, after passing through the Venturi section I4, is discharged from the burner nozzle through the port 20 into the combustion zone I2 where it is admitted through opening ll, passes through space 2| between the burner'tip and the firing block 22 and burned. Additional air forcom-' bustion commingles, in passing through firin port 20 with the fuel-air mixture from the bumer," passing therewith into the interior or the heater.- The'block 22 is made of suitable refractory material and supported by the floor 3 and shell portion 4. A checker-work 22, made up of fire-brick or the like, is provided immediately above burner port 20 to difluse the flame and give more uniform distribution of the radiant heat.

' The flames and hot combustion gases are directed upwardly from the burner port 20 and the checker-work 23 through the heating zone I 2 and a substantial portion of their heat is given up,

v by direct radiation and convection to the tubular coil II. The hot gases continue upwardly, passing in direct and intimate contact with the tubular elements I I-, comprising coils to which fluid heat is supplied from the combustion gases. The products of combustion are finally directed through the stack I to the atmosphere.

The supporting means'for the coils II and II are the subject of my aforementioned co-pending U. S. application Serial Number 236,681, flied October 24, 1938, and comprise, in the instance herein illustrated, three vertically disposed tubular elements 24, approximately equally spaced on.

which are suitable ior'use with other terms of fuel, such as, for instance, fuel oil, when desired.

heater at the. lower end of coil ll, absorb substantial quantities or radiant and convection heat and then bymeans of conduit 30, will be divided into two substantially equal streams.

One of said streams will now through the lowermost coil I I, then by means of conduit 2|, will be directed into the third from the lowermost coil II, through which it will flow and be, in turn,

directed by, means of conduit :3, to the nan coil from the lowermost coil II through which it will-pass and be directed by conduit 35, to con-' duit 31 where it will be Joined by the other stream which has in the meantime passed serially through the remaining individual coils II. Flow in the reverse or generally downward direction through the heater, which is also contemplated by the invention will be apparent without detailed description.

arrangement of these coils, which comprise two helical shaped tubular elements Ill and .lil" which are disposed about the heating zone I2 and are heated by radiant and convection heat.

a circle somewhat larger in diameter than that a about which the tubular element of coil I0 is I wound. The several turns of coil It may be secured to the elements 24 by means of -u-bolts 25,

as shown, or the coil ll maybe welded or otherwise suitably attached to the supports. Radial members 28, attached to 'theupright elements 24 by boltsor other suitable means, serve to support the flat spiral coils I I. The lower ends of elements 24 rest upon the foundation 8, and are provided with openings 28therethrough adja cent their lower ends within'zone I.

The natural graft created in the furnace and acting upon the open upper ends oithe tub serves a: a means of drawing air from the spad 1, into and through theinterior. of the tubes, thereby cooling them. When desired, insulation, as shown, may be provided aroundthe-support?- ing elements 24 in the lower portion of zone I2 where they are exposed to extremely high temperatures.

Theupper end of coil III is connected by means of the tubular conduit III to the two lowermost flat spiral coils II and the alternate coils II are then each connected in series by means of conduits 3|, 32, 33 and 34 to provide two substantially equal paths for the flow of fluid being heated. The inner ends of the two uppermost coils II are connected by conduits l5 and 36 to the conduit 31. By arrangement here illustrated, assuming the flow of fluid is in a generally upward direction, the stream would enter the- The flat .spiral oils of-the upper tube bank I I are similar to t ose shown in Figures 1 and 2 and alternate coils are serially connected by means of conduits 30', 30", 3|, 32', 33', 34, 35 and 38' to provide parallel paths of flow for two separate streams of fluid. 0011- I0 is connected by means or conduit 30 in series with the lower- .;most coil of bank II and consequently with each alternate higher coil of this bank. Coil I0",is connected by conduit 3| in series with the sec- .ond from the lowermost coil of bani: II and with each alternately higher coil of this bank. Thus,

two separate parallel paths are provided for the passage of fluid through the fluid conduits oi' the heater.

It is entirely within the scope of the invention to employ more than two parallel streams illustrated in the accompanying diagrammatic drawings by providing more flat spiral coils and more than two helical coils.

I claim as niy invention: A heater comprising, in-eombination, a verticaily disposed, substantially cylindrical, refractory wall defining a radiant heating zone and a.

fluid heating zone disposed above and in direct communication with said radiant heating zone,

' a pair of tubular fluid conduits, each comprising a plurality of helical turns, disposed in said 1 radiant heating zone adjacent the surface of said wall, a first set of superimposed and serially connected fiat spiral coils disposed in said fluid heating zone and communicating with one of said conduits, a second set 01' superimposed and serially connected flat spiral coils disposed in horizontal planes alternating with' the horizontal planes of the coils of said first set and'communieating with theothe'r of said conduits, means for projecting hot combustion products upwardly through said heating zones, and means for supplying a stream of fluid to each of said conduits.

MARION w. BARNES

Images