US2634712A - Fluid heating unit - Google Patents

Description

April 14, 1953 v F. L. KALLAM 2,634,712

FLUID HEATiNG UNIT Filed Aug. 1'7, 1951 3 Sheets-Sheet l I ATTORNEY April 4; 1953 F.. L. KALLAM 2,634,712

FLUID HEATING UNIT 3 Sheets-Sheet 2 Filed Aug. 17 1951 Puma/m ATTORNEY April {4, 53 F. L. KALLAM 2,634,712-

FLUID HEATING UNIT 3 Sheets-Sheet .5

filed Aug. 1'7, 195].

INVENTQ n F. L. KALLAM aya.

AT'TOHNE Patented Apr. 14, 1953 UNITED STATES FLUID HEATING UNIT.

Floyd L. Kallam,

Industrial Engineers, Inc., Los

Pasadena, Calif., assignor to Angeles, Calif,

a corporation of California Application August 17, 1951, Serial No, 242,233

4 Cl ms- 1 The invention relates to a unitary heater or furnace providing successive coaxial zones of hotgas heating for a tube-carried fluid by radiation and convection respectively.

An object of the invention is to provide a particularly efficient heat exchange in the convection zone of a heater of the present type.

Another object is to provide for the ready incorporation of the convection zone control means in existing heater structures.

A more specific object is to provide for a circulation of the heated gases circumferentially through a circular bank of fluid-carrying tubes in the convection zone of the heater.

The invention possesses other objects and features of advantage, some of which, with the foregoing, will be set forth or be apparent in the following description of a typical embodiment thereof, and in the accompanying drawings, in which,

Figure 1 is an elevation of a vertical tube liquid heater embodying the features of my invention.

Figure 2 is a sectional view taken at the line 2-2 in Figure 1.

Figure 3 is a stepped section taken at the line 3-3 in Figure 1.

Figure 4 is a fragmentary section taken at the line 4-4 in Figure 1.

Figure 5 is an enlarged fragmentary axial section of the heater taken on the line 5-.5 in Figure 1.

Figure 6 is a section taken at the line E6 in Figure 1.

Figure 7 is an enlarged showing of a portion of Figure 4.

Figure 8 is an enlarged fragmentary section taken at the line 8B in Figure 4.

Figure 9 is a section taken at the plane of the line 9-9 in Figure 1.

Figure 10 is a sectional view taken at the line [0-40 in Figure 1.

Figure 11 is an enlarged fragmentary section taken at the line ll-I l in Figure 10.

Figure 12 is a generally diagramatic axial section of the essential heater structure and arrangement.

Figure 18 is a perspective broken-away view of an element defining a convection section of the heater.

Figure 14 is an enlarged fragmentary view at the line ill-i4 in Figure 10.

As particularly illustrated, the features of my invention are incorporated in the structure of an industrial liquid heater having a circle of liquid-carrying tubes 2 l extending axially through a cylindrical combustion and heatetranse, fer chamber defined within an upright cylindri-w cal metallic shell N3 of circular cross-section pro; vided with a heat-insulation lining I8 disposed between it and the tubes. In the present struc. ture, the tubes 2| extend through and between upper and lower tube plates I9 and 20 of circular outline suitably fixed to and within the sh ll. The tubes 2| are connected in pairs at their tops above the tube plate I9 by U-bend, or junction box, fittings 23, and adjacent tubes of the pairs are connected at their bottoms by like U-bend fittings 24, except that one pair of adjacent said tubes depending from adjacent top fitting-s 23-, is connected at their bottom ends with intake. and discharge pipes 25 and 26 extending radially of the heater axis by elbow fittings 21. The are rangement is essentially such that liquid entering the tube system from the intake pipe 25 is con-. ducted from end to end of the tube assembly in a generally zigzag path to the discharge pipe 26. The upper tube plate I9 is annular, and the present tube assembly is suitably suspended therefrom in a manner which provides for and permits the necessary free thermal expansions of the heater parts.

At its top, the shell 22 mounts a stack assembly comprising a cylindrical base portion 28 lined with insulation 28 and complementarily fitted within the central opening of the annular upper tube plate l9, an intermediate conically tapered portion 29, and a uniform flue portion 30 having a suitable damper 3| installed and operative in its bottom end. The present heater unit is of a, relatively large type for use in the petroleum and chemical industries and having a ladder-andwalkway structure provided about it, with the walkways leading to various access openings at heater and stack points at which access might be needed through doors or portholes provided in the shell; the size of the heater unit and the specific ladder-and-walkway arrangement are both generally immaterial to the present inven!- tion which primarily concerns the control of heat transference from hot gases within the chamber 34 of the heater to a fluid in the tubes 2|. The bottom of the chamber 34 is defined by the disc.- shaped lower fire tube 20 and an overlying crosswall 35 of fire brick or the like, beneath which mutually spaced fiuid burners 36 are provided in a circle coaxial with the chamber to have their fiame jets discharging into the chamber through passages 31 provided in tubular members 38 mounted in the chamber bottom 20- 35.

As is particularly brought out in Figures 5 and 10 to 12, the burners 36 are arranged for burning a fuel gas mixture which is derived from a common fuel-supply pipe 4! and a common air-supply manifold pipe 42 through airmixing valves 43 supplied from the pipes 4| and 42 under suitable valve controls. A manifold pipe 44 disposed slightly above the coplanar valves 43 has branch pipes 45 discharging a fuel gas adjacent the burner nozzles 36' to constantly provide ignition jets thereat. The bores of the tubular members 38 are of generally Venturi form, are arranged to have the combustible fuel-air mixture directed axially therethrough and therefrom into the chamber 34 for combustion in the chamber, and provide space about the jet streams for the entrained supply of combustion-supporting air from beneath the chamber bottom. The nozzles 36 of the burners 36 preferably discharge the fuel mixture to provide a symmetrical flame burst axially in the chamber 34. Alternatively, hot gaseous combustion products from a separate combustion zone may enter the chamber 34 through the members 38 for accomplishing the present tube-heating purpose. Also, the hot gases which are to provide a tube-heating stream through the chamber 34 are not necessarily combustion products, and may, for instance, comprise air which is electrically, or otherwise heated within or without the chamber.

The annular upper tube plate l9 has insulation rings 41 provided directly beneath it, and is cooperative with an angle-section shell-capping ring 48 and the flue base 28 to provide a closed header-box space 49 which receives the top headers 23. The central openings of the tube plate l9 and shell cap 48 closely receive the stack base 28 which is supported from a seat ring 50 fixed to its exterior to rest upon the tube plate. For providing access to the headerbox space 49. the shell cap 41 has a releasable connection with the shell portion beneath it, as by a flanged ring or band The upper tube plate I9 is particularly shown as engaged by the bottom ends of the tube-mounted headers 23 for supporting the tubes therefrom, and the arrangement at the shell top is essentially such as to provide for the ready dismounting of the cap and stack and tubes and upper tube plate, as may be required for the inspection or replacement of parts.

It will now be particularly noted that an intermediate annular tube plate 53 extends inwardly from the shell H3 at a point somewhat below the .top tube plate I 9, has the tubes 2| slidably engaged through transverse openings therethrough, and divides the chamber 34 to provide lower and upper sections 54 and 55 thereof. The lower chamber section 54 so defined includes the combustion zone for the heater, and the hot gases comprising the combustion products are arranged to flow axially upwardly in that chamber portion to and through the central opening of the annular tube plate 53 which is defined inwardly of the tubes, and therefore provides thereat a slight contraction of a rising stream of the hot gases thereat. The hot gases pass upwardly along the tube portions in the lower chamber part 54 without marked turbulence to provide for a chiefly radiant transfer of heat from the gases to the tubes and so to the liquid stream circulating through the tubes, and the space 54 may be referred to as a radiation zone of the heater by reason of this major manner of transfer of heat therein.

Understanding that the upper chamber section 55 defined above the tube plate 53 receive t hot gases which still contain heat energy for transfer to the liquid stream in the tubes, means are provided in said section for positively directing said gaseous products into direct contact with the tube portions therein whereby all possible heat exchange may be completed thereat by conduction for an operation of the heater, such that the combustion products escaping to and through the stack 28 by convection may have the lowest possible temperature. Essentially, the desired control of the gas flow and heat exchange action in the upper chamber section 55 is provided by inserting coaxially therein a unitary element '56 of cylindrical outline which functions as a baffie plug to guide the rising stream of heating gas directly against the tubes for the desired purpose. The cylindrical element 56 is arranged for its mountin and dismounting from above the space 48 while the stack is removed, and has its bottom portion formed for its central seating on the intermediate tube plate 53 to support it in its operative position in which its top is close to the bottom of the mounted stack base 28.

Referring specifically to the structure of the member 56, it will be noted that this element is of generally drum-like outline having a tubular side 51, closed semi-circular top and bottom ends 58 and 59 respectively having their straight edges in a common plane and connected by a flat plate 6| which is diametral of the side 59 and bisects the element space. The interior arrangement of the member 55 is essentially such as to provide semi-cylindric chambers 62 and 63 below and above the top and bottom ends 58 and 59 of the member. Interior axial slots 64 and 65 are provided in the side 51 at opposite sides of the par tition GI and in a common diametral plane which, in the present instance, is perpendicular to the partition plane, said slots being arranged to function as ports with respect to the chambers 62 and 63 of the member for a purpose to be hereinafter brought out. A manhole 66 which is normally closed by a cover 6'? is provided in the upper end 58 of the member 56, and hook elements 68 extend upwardly from the partition 6i for use in supporting the member 55 during its removal and installation in the heater. Since the inserted element 56 is arranged to have the bottom edge of its tubular side 51 supportedly seat upon the top of the tube plate 53, a conically tapered flange 69 extends downwardly from the bottom of the member and below the plane of its bottom end 59 as the sole means for assuring a centered and rotatively adjusted positioning of the member upon the intermediate tube plate 53.

Noting that the stack base 28 is in effectively sealed relation to the baffle member 56 around the top of the member side 51, the stream of hot gas entering the open-bottomed chamber 62 through the central opening 53 of the tube plate 53 will escape from the chamber through the port slot 64, flow circumferentially around the member in both directions in the annular space H defined between the member side 51 and the opposed shell wall to leave the space H at the port slot 65, and thence flow upwardly through and from the chamber 63 into the stack. The circumferential and generally horizontal flow of gases through the space H is arranged to effect the desired final heat transfer from the gases to the portions of the tubes 2| in said space in a particularly intimate manner for assuring a maximum heat exchange thereat. If desired, the tube portions within the space H may mount annular heatconducting fins 12 for further assuring a maxi mum heat-exchange action with respect to the liquid stream in the tubes. Noting that the final heat exchange action of the present heater occurs in the space H in which the convection flow of the heating gases into the stack is responsible for the flow relations provided in the space, said space may be referred to as a convection zone in accordance with the established practice in the art, and in contradistinction to the radiation zone provided by the lower section 54 of the heater chamber.

Considering the present heater generally, it will be understood that the tubular shell thereof provides a cylindrical radiation zone in which the gas flow is axial, and a coaxial annular convection zone in which the gas flow is transverse to the common axis of the zones for insuring a maximum degree of final heat exchange between the hot gases and the tube-carried fluid to be heated. Under certain conditions, the rotatively adjusted positioning of the baffle member 56 may effect the thermal efficiency of the present heater; as particularly illustrated, the discharge port 64 of the member 55 is disposed at the diametrically 0pp0- site side of the cylinder of the heat-exchange space from the intake and discharge connections for the series-connected tubes whereby the gas passing in one direction from the inlet port 54 for the convection zone II will contact tubes carrying the liquid stream at progressively lower temperatures, while the gas passing in the other direction about the member will contact tubes carrying liquid of increasingly higher temperaure.

As compared with previously known heaters providing successive and coaxial radiation and convection zones of heat transfer utilizing a hot gas stream through both of them, a continuousflow heater having the present arrangement is more efficient for a given total tube length, whereby generally smaller units of its type may provide a desired heat transfer at a predetermined rate. It will also be understood that a present heater combination may operate with equal efiiciency if its longitudinal axis is disposed horizontally and the stack base discharges as a breeching into an upright flue. Also, with the convection zone extending for between onefourth to one third of the heat transfer space of the shell, this space or zone will provide about thirty percent of the heat-exchange duty of the heater.

From the foregoing description taken in connection with the accompanying drawings, the advantages of the present heater will be readily understood by those skilled in the art to which the invention appertains. While I have described the principle of operation, together with a form of my invention which I now consider to comprise a preferred embodiment thereof, I desire to have it understood that the showing is primarily illustrative, and that such changes and developments may be made, when desired, as fall within the scope of the following claims.

I claim:

1. In a furnace structure, means defining an elongated heat-exchange chamber arranged for the longitudinal flow of initially hot gases therethrough, a bank of liquid-carrying tubes mounted around the periphery of said chamber and extending longitudinally therethrough, a source of hot gases at the intake and of said chamber, and a hollow baffle member of cylindrical outline mounted coaxially within the bank of tubes and at the discharge end of the chamber and operative to effect a circumferential heat-exchanging flow of the gases within the chamber portion defined about the member, said baffie member being longitudinally and diametrically partitioned to provide semi-cylindrical intake and discharge chambers having intake and discharge openings at opposite ends of the member, and the sides of said intake and discharge chambers being respectively provided with relatively narrow discharge and intake ports extending longitudinally therealong at diametrically opposite side points of the baffle member for substantially the full length of the member to provide for the external gas flow between said ports to fully encircle the member.

2. In a furnace structure, means defining an elongated heat-exchange chamber arranged for the longitudinal flow of initially hot gases therethrough, a bank of series-connected liquid-carrying tubes having suitably adjacent intake and discharge connections and extending longitudinally in and around the chamber, a source of hot gases at the intake end of said chamber, a hollow baffle member disposed coaxially within the bank of tubes and at the discharge end of the chamber and operative to effect a full circumferential heat-exchanging flow of the gases within the chamber portion defined about the member, the space of said baffle member being longitudinally divided by a single partition to provide intake and discharge chambers having intake and discharge openings at opposite ends of the member and respectively having the member side portions thereat provided with relatively narrow discharge and intake ports extending longitudinally therealong for substantially the full length of the member at opposite side points thereof, and means mounting said bafile member for a rotary adjustment of the member about the chamber axis for variably disposing its said ports with respect to said tube connections.

3. In a furnace structure, means defining an elongated heat-exchange space of circular crosssection arranged for the longitudinal heat-exchanging flow of hot gases therethrough, a, bank of liquid-carrying tubes for carrying a stream of fiuid to be heated mounted around the periphery of said chamber and extending longitudinall therethrough, a source of hot gases at the intake end of said chamber, and a hollow baflie member of cylindrical outline mounted coaxially within the bank of tubes and at the discharge end of the heat-exchange space to define an annular heat-exchange chamber between its side and the space periphery and closed at its ends and receiving therethrough portions of the tubes longitudinally therethrough, said bafiie member being longitudinally and diametrically partitioned to provide semi-cylindrical intake and discharge chambers having end intake and discharge openings respectively corresponding to the intake and discharge end of the heatexchange space, and being respectively provided at solely diametrically opposite points of the side wall thereof with discharge and intake ports comprising relatively narrow slots extending longitudinally of the member whereby gases entering the intake chamber of the member will fiow from the discharge port thereof circumferentially around the member in a divided stream to the intake port for the discharge chamber and thence from the furnace.

4. In a furnace structure, an upright tubular shell defining an elongated heat-exchange chamber for the longitudinal upward flow of initially hot gases therethrough, a bank of series-connected liquid-carrying tubes extending longitudinally in and around the chamber and having mutually adjacent intake and discharge connections, a source of hot gases at the lower end of said chamber, a hollow cylindrical bafiie member disposed coaxially Within the bank of tubes and at the discharge end of the chamber and operative to effect a full circumferential heatexchanging flow of the gases within the chamber portion defined about the member, said baffie member being longitudinally and diametrically divided to provide intake and discharge chambers having intake and discharge openings at their lower and upper ends respectively and having the member side portions thereat provided with relatively narrow discharge and. in-

References Cited in the file of this patent UNITED STATES PATENTS Number Name Date 2,340,287 Throckmorton et a1. Feb. 1, 1944 2,454,943 Reed Nov. 30, 1948 2,514,279 Gleber July 4, 1950

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