US2825313A - Heaters - Google Patents

Description

March 4, 1958 l I s. BORN ETAL 2,825,313

March 4, 1958 s. BORN ETAL HEATERS 2 Sheets-Sheet 2 Filed Jan. 10, 1955 United States- Patent HEATERS Sidney Born and Harold Jay Born, Tulsa, Okla., assignors toBorn Engineering. Company, a partnership Application January 10, 1955, Serial No. 480,949

6 Claims.. (Cl. 122-356) been developed, it is advantageous toy have. the heating elements vertically suspended, which arrangementreduces ldifliculties encounteredwhen tubes are horizontally positioned or when vertical tubes yare supported from below. Other problems continually confronting engineers responsible for heater ydesign is the uniform distribution of radiant and convection heat over the heat exchange surfaces,l the free unobstructed flow of combustion gases through the heater, and accurate control of the heat supplied to the combustion chamber'and an efficient Aadjustment of the amount of heat to all parts of the combustion ychamber and heat exchange elements.

An object of the invention therefore is to provide ya heater construction in which combustion gaseshave a free unobstructed flow from thev sources of heat through the combustion chamber and a tubearrangement adapted to eiciently extract a maximum amount of heat from the gases during their passage through the combustion zone.

Another object is to furnish an arrangement of the heat exchange elements so that a maximum surface willbe exposed both to convection and radiant heat.

A further object is to provide a construction or design in Swhichv the reflecting walls of the furnace or heater will uniformly distribute the radiant andtconvection heat onto the heat exchange surfaces.

Another object is to utilize the air supplied to the heat sources and forming a part of the combustion gases as an insulating blanket around the side walls of the heaters to thereby preheat such air and effect more eilicient comn bustion. Other and further objects will appear from the description which follows.

In the accompanying drawings which form a part of the instant specification there is shown an embodiment of the invention, and like reference numerals are used to indicate like parts in the various views.

Fig. 1 is a side elevation of a heater embodying the invention with parts broken away to show the manner of suspending the tube bank centrally thereof.

Fig. 2 is an end view of the heater shown in Fig. 1 with parts broken away.

Fig. 3 is an enlarged detail of the tube hanger construction.

Fig. 4 is a view taken along the line 4-4 in Fig. 3. Fig. 5 is an enlarged perspective detail of a tube hanger Hug' rifice Fig. 6 is a. plan view` of a section ofthe oor ofthe heater taken along the line 6 6 in Fig. 2.

Referring to the drawings, and particularly to Figs. 1 and 2, upon piers l0 are transverselbeams 11 which support'the oor l2. The side and end walls of the heater comprise a metal frame made up of vertical membersv 13 and horizontal cross members 14 which carrythe exterior panels -15 and` blocks of lire resistant ceramic material 16 which form `the inner walls kof the heater and reflecting walls of the combustion chamber.v The top enclosure is likewise refractory material shown diagrammatically at 17 supported by suitable longitudinal and horizontal framework indicated at 18. A breeching comprising tubular ducts 19 and, 19a conduct the combustion gasesfrom the top'of the furnaceinto a stack 20. Dampers 21 in the breeching are manually controlled from cranks 22 through cables 23 and pulleys 24 mounted upon the damper shafts.'- Between the inner walls of fire brick 16 and ,the outer jacketing panels 15 are air ducts 25 provided vwith an inlet 26 extending longitudinally of the heater near the top and horizontal ducts 25a beneath the hoor' 12 whereby air is drawn from the atmosphere through theinlets 26, passed downwardly between the inner and outer walls of the heater and dischargedV into burners 27 where it is combined with fuel supplied through pipes 2S. to form the combustion gas used in the heater. These burners 27 are closely spaced at intervals along the bottom of the'heater as shown in Fig. 6.

Running longitudinally ofthe heater and suspended from the top frame 18 is an I-beam 29 shown best in Fig. 2. From. this I-beam are suspended the, heat exchange elementsthrough. which lluid is passed in ,transferring heat from the combustion chamber to such fluid.. The heat exchange elements consist of a bank of verticaltubes 30 arrangedin rows centrally of the heater withthe tubes in the separate banks staggered with relation to the tubes in the Yother bank so a maximum amount of surface will be exposed to the heating gases passing upwardly through the separate vertical ducts formed by the centrally positioned tube bank. In other words, the` vertical tubes in one row arearranged opposite the space between the tubes in the adjacent row so convection and radiant heat from the two vertical combustion compartments or passageways between the burners 27 and the outlet breeching is distributed uniformly over the tube surfaces.

At the top the return bends 30 joining the tubes are suspended from beam 29 by hanger rods 31' andrings 32. The lower ends of the rods have apertured yokes 31a which straddle lugs 32a on top of rings 32. Pins 33 held by cotter pins extending through the holes in the bifurcated-portions of the hanger and the eyes in lugs 32a furnish an easily removable connection between'the hanger rods and the tubes. An inlet connection 34 to the initial tube of the bank provides a means by which fluid is supplied to the tube bank and a corresponding connection 35 discharges the uid after it has been heated. These connections are conveniently arranged at a level so they may be easily manifolded to the tube bank in order that the fluid may be supplied to a plurality of tubes simultaneously and discharged from a plurality of tubes at the discharge side of the bank. Such arrangement permits altering the capacity of the heater with but little structural change.

The heat sources 27 shown as burners in Fig. 6 are closely spaced in the oor of the furnace or heater so all or any number may be used on either side of the tube bank offering a exible control of heat to the combustion zone.

In the lloor and enclosing the lower end of the tube and return bends is an insulated tunnel 36 running longitudinally of the heater. In this tunnel are access plates 36a through which tubes may be removed from below, since the access plates run along the bottom 0f the tunnel,

and the heater is raised sufficiently on the piers to permit handling of the tubes through these lower access openings.

The inner side reecting walls of the heater are sloped or inclined at a proper angle inwardly from bottom to the top of the` combustion jcharnberfor the purpose of more uniform distribution of radiant andconvec'tionlheatupon the surfaces of the tubular elements 30. At the lower part of the combustion` chamber `the reflecting walls are relatively remote from the tubes where the heat is the greatest. The inclination of thewalls is such that the reflecting` surface is closer to the tubesnear the top where the reflected heat isA least.` The' convectiontheat absorption is a function of the cross sectional area of the furnace and as the temperature of the convection gases decreases the cross sectional,l area is also decreased, to main tain a constant heat absorption. By inclining the walls or sloping the walls inwardly at a predetermined angle from bottom to top the vertical ducts on opposite sides of the tube bank are shaped so both radiant and convection heat is more uniformly and evenly distributed upon the surfaces of the heat exchange element. The angle at which the side walls are sloped or inclined will depend to a great extent upon the height of the combustion chamber and the length of the tubes or heat exchange elements which are serviced. As previously suggested, air supplied to the burners or heat sources is first circulated through the plenum chambers or ducts 25 surrounding the side walls of the heaters and besides serving as insulating blanket preheats the air before introduction to the combustion chamber.

From the foregoing, it will be seen that the invention is one well adapted to attain all of the ends and objects hereinbefore set` forth, together with the other advantages which are obvious and which are inherent to the structure. The previous description is intended to be explanatory of a construction which embodies the invention, but it should be noted that various changes in the size, shape and materials used may be made, as well as the details of the illustrated construction, within the scope of the appended claims without departing from the spirit of the invention. i

Likewise, it will be understood that certain features and subcombinations are of utility and may be employed without reference to other features and subcomhinations. This is contemplated by and is within the scope of the claims.

Having thus described our invention, we claim:

1. ln a tubular heater for fluids, the combination with side walls, a Hoor, a top enclosure with flue gas breeching and a stack, tube support means fixed within the heater adjacent the top thereof, a bank of vertical tubes suspended from the tube support means adjacent the top of the heater `and arranged centrally thereof, said bank of tubes extending from the oor to substantially the top of the heater the vertical tube bank comprising at least one row of tubes with adjacent tubes positioned so closely next one another as to partition the combustion zone of said heater substantiallyinto two vertical gas ducts extending from the oor to the top of the heater, tubular return bends detachably connected at the tops and bottoms of the tubes to form a continuous flow-way therethrough `from one end of the bank tothe other, inlet and outlet connections to the bank extending through the wall of the heater, means for supporting the bank from the tube support means comprising a plurality of individual releasing suspension means connected to a plurality of upper bends of the bank, removable access means in the floor of the heater whereby tubes may be removed and replaced therethrough, and heatsources in the bottom of each of said ducts.

2. A heater as in claim 1 wherein the individual suspension means 'are connected individually to each upper bend of the bank to individually support each loop of tubing in the bank.

3. A heater as in claim 1 wherein the side walls of the heater are sloped inwardly from bottom to top throughout the combustion zone whereby radiant and convection heat is uniformly distributed over the surfaces of the tubes in said tube bank, means forming plenum chambers adjacent the side walls and extending essentially the entire length thereof with air inlets at the top of said plenum chambers and discharge outlets through the floor of the heater whereby the air stream through said plenum chambers aids in insulating the side walls and provides preheated air to the heat sources.

,4. A heater as in claim 1 wherein said heat sources in the bottom of each duct comprise a plurality of individual heat sources spaced along the width of the bank whereby heat may be applied through each individual source to a limited width of the tube bank whereby to permit differential heating across the width thereof.

5. A heater as in claim l wherein said inlet and outlet connections are arranged in the same horizontal plane as the upper tube bends whereby manifolding of the tubes in multipassfarrangement is facilitated.

6. A heater as in claim l wherein the vertical tube bank comprises at least a double row of tubes, the tubes in each row staggered with respect to the tubes in the adjacent row or rows yet positioned apart one from another a distance not greater than the outer diameter of the tubes, the tube bank partitioning the combustion zone of said heater substantially into two vertical gas ducts extending from the floor to the top.

References Cited in the file of this patent UNITED STATES PATENTS 1,989,612 De Florez Jan. 29, 1935 2,294,977 Garrison et al. Sept. 8, 1942 2,374,797 Barnes May l, 1945 2,416,273 Wallis et al Feb. 18, 1947 2,456,787 Kniel Dec. 21, 1948 2,557,569 Schutt June 19, 1951

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