US2579350A - Furnace - Google Patents

Description

L. J. WEBER Dec. 18, 1951 FURNACE Filed May 1, 1946 ATTORNEYS:

INVENTOR LOUIS J. WEBER Patented Dec. 18, 1951 Phillips Petroleum Company, a corporation of Delaware inventionrelates to fumaces. In one of its morespecific aspectsit relates to an improved design of furnace especially adaptedfor heating petroleum or petroleum products and other fluids. This application is ,a continuation-in-part of my copending application; Serial No. 512,284, filed NovemberQ29, 1943 and now Patent No. 2,528,564. L

Conventional furnaces, used for preheating or cracking petroleum products andfluids, ordinarily comprise a fire box set on a concrete foundation and having solid mas'onryyor refractory bridgewalls rising from the floor thereof to a point a spaced distance from. the top member of the furnace. Such furnaces are ordinarily provided with a separate flue gas stack base or foundation and combustion gasesare' conveyed from the lowenportion of the furnace, between the bridgew'alls, through an underground duct to the separate flue gas stack. Burners in such conventional furnaces may be disposed in walls opposite the solid bridgewalls. Tubes may be provided as convection tubes between the bridge-' walls, and floor tubes, vertical sidewall tubes and roof tubes in a radiation section.

In furnaces of that type, the combustion gas and flames from the burner tend to'take a generally upwardlyand inwardly direction, the combustion gas escaping over .the topof the bridgewalls, down over the convection tubes and out through a duct to the stack. That type of combustion gas flow fails to provide the amountof heat to thefloor tubes and vertical wall tubes that is provided to the roof tubes. Inasmuch as the flow of materials to be heated or cracked is through the convection tubes. floor tubes, vertical wall tubes, and rooftubes, the material passes from a zone of relatively high heat input into zones of lower heatinput in the floor and wall tubes. These low heat input zones are sometimes known as high temperature soaking, zones. Such zones are conducive to" the formation of tars often destructive. It is thus necessary, "in erecting the conventional furnace, to first lay an extra heavy foundation in order to withstand the destructive heat.

' The furnace of the instant invention solves the problems above enumerated. This device is an end fire box type furnace provided with slanting roof and floor sections connected by substantially Vertical'side' walls; The slanting floor section is so supported on a reinforced concrete foundation that it is air cooled and thus requires less concrete than' 'is required inthe construction of a foundation or base for conventional furnaces. I and are suspended from beams in the roof so as to be free floating within the furnaceand are spaced from the furnace floor so as to allow the passage of combustion gas thereunder. 'I'he'fiue stack is also supported by the beams in the roof which support the bridgewalls. It will thus be' seen that the'stack of the instant device may be somewhat shorter in length than that 'used in conventional furnaces. The above mentioned roof beams are preferably supported by main central columns in line with the bridgewall outside the furnace structure. The main roof beams are parallel to the short dimensions of the furnace and are supported at their ends by these main central columris. Tubes in the furnace of the instant invention are only in some ways similarly disposed to those within conventional furnaces. Convection coils are separated from radiation sections by hollow bridgewalls. Floor tubes are disposed along the slanting floor so that the tube bank slopes outwardly and upwardly,

parallel to the sloping floor. "Vertical wall tubes are aflixed in a position, parallel to the vertical wall, and the roof tubes extend downwardly and l outwardly parallel to the roof of the furnace. In

- the instant invention than in a conventional and carbon which reduces the yield of desirable surfaces of the combustion cone emanating from Another disadvantage of the conventional furmice is that no provision is made. for the escape of heat from the bridgewalls. For that reason it is mandatory thatthelrtemperature of the bridgewalls be kept under close surveillance to keep from burning them out. The concrete founda-..

tion is'in much thelsame category. Highf'temperature, when applied to uncooled concrete, is

this arrangement of tubes, more actual heat absorbing surface can be placed in a furnace of furnace of equivalent fire box volume. I The floor and roof tubes are disposed in such a manner as to be approximately parallel with the. sloping burners in the furnace walls opposite the bridgewalls. With a furnace oi? the instant invention combustion gas ispartiallyVbottled up) in the radiant section above the level of the combustion gas outlet beneaththe b'ridgewallsy, Heat travels more equally toall parts of theradiationzonev and exposes the heat'absorption area. of fall of the floor tubes to amorel uniform heat; thanis, possible in conventional furnaces.

The bridgewalls are air cooled" Combustion The bridgewalls 6' are in gases flowing out of the radiant section into the convection section flow downwardly under the bridgewalls and contact that portion of the tubes below the combustion gas outlet and those in the convection section.

An object of my invention is to provide a simple and efficient furnace unit which can be constructed on less ground space and with the use of less critical materials than required by conventional designs.

Another object of my invention is to provide a furnace of such design as to utilize fully and efliciently the radiant heat to achieve a highly eilicient rate of heat input to the tube coils.

I Many'other objects and advantages of my furnace will be apparent to those skilled in the art from a careful study of the following detailed description, which taken in conjunction with the attached drawing respectively describes and illustrates one embodiment of my invention.

In the drawing; Figure 1 is a cross sectional view of my furnace taken on the line [-1 of Figure 2.

Figure 2 is an end elevational view in diagrammatic form of a preferred embodiment of my furnace.

Figure 3 is a cross sectional view, in part, of the space between the two sides of the bridgewall taken on the line 3-3 of Figure 1.

Figure 4 is a sectional view of a furnace of this invention showing a bridgewall and a furnace wall in spaced apart relation.

Referring to Figure l, the furnacetubes are separated into two main groups. Some convection tubes are represented by l' and some radiant tubes consisting of floor tubes are repre-' sented by I, slanting roof tubes by 2' and vertical side wall tubes by 3'. 'I'heconvection tube bank is suspended from a central framework comprising two principal cross beams 8' which in turn are supported by four central framework columns ll, vertically disposed and at the corners of an imaginary rectangle. The cross beams 8' also support the stack 1'. Slanting roof beams 16' are supported at one end by the beams 8 and at the other end by the buckstays or outer framework columns 13'. In turn, the slanting roof beams I6 support the fire box arch brick 9', and

the roof covering ID. The buckstays 13' support the refractory fire brick walls l1 and form end wall sections.

-The entire structure is supported upon any .suitable base such as a reinforced concrete foundation, part of which is shown as IS. The refractory linings for the furnace are attached to the beams by any suitable and well known construction, and therooftubes 2' and the vertical wall tubes 3' aresupported by means of alloy castings A attached'to beams li'and buckstays l3 respectively in any suitable and well known manner.

Suspended also from the main beams 8' are the refractory bridgewalls 6 which, as illustrated, are hollow and form vertical passages la (Figure 3), and,are open at the ends so that air from the outside may enter them and flow inwardly and upwardly through these passages 8a and past the I-beams 8' and be discharged into the atmosphere. The burners 5' open into the furnace in a direction to impinge their. flames on thebridgewalls 6'.

ed curtains-and comprise a series of vertical columns 8b connected together at the bott'omby v means oi full floating I 9". The-refractory the. form-of suspendwalls themselves are composed of fire brick tile attached to this curtain in any suitable and well in Figure 1. The bridgewalls, being unattached at their ends to walls ii of the furnace, are truly suspended curtains capable of any necessary movement to allow,for expansion. and contraction thereof as shown in Fig. 4 of the drawings.

The inner side member 2| of each of the bridgewalls extend up toward the stack at least sufliciently far as to protect the I-beams 8' from the hot combustion gases as they leave the conwalls and then upward through said convection;

vection section and enter the base of the I stack 1f.

These bridgewalls 6' are in the form of suspended double walled curtains with a ventilating space in each. Between the refractory walls 5' are several vertical steel I-beam type members 8b, see Figure 3. These several members are parallel to one another and the upper ends of which are attached rigidly to the under side of the I- beam cross members 8', and thus hang downward from said I-beams. To these hanging steel members 8b are attached lugs, or other hooking members, not shown, and upon which the refractory blocks forming the main refractory portion of the bridgewalls hang. To the bottom end of said vertically disposed I-beam members 8b is attached a horizontally disposed I-beam or channel member 19'. This member merely serves as a bottom framework member.

Thus from the bridgewall construction it will be seen that each entire bridgewall hangs from its respective upper I-beam 8' and may expand or contract at will due to thermal causes.

The vertical I-beam members 8b and the horizontal I- or channel member I! are perforated in the web to permit passage of atmospheric air for cooling. Thus atmospheric air enters the space within each bridgewall. and may pass from one opening 8a to another opening la and upon becoming heated rises to pass from these spaces around the I-beam 8' to the atmosphere. These hollow bridgewalls 8' extend all the way .across the furnace and being spaced in the furnace as illustrated in Figure 1 terminate above the floor of the furnace thereby leaving a i'rce passageway from each fire box into the common convection tube section. Thus the burned gases may freely pass from the-combustion chambers or fire boxes downward and under the bridge tube section and finally into the stack I proper. In operation, the fluid to be heated enters'the furnace at the top of the convection tube bank I and progresses downwardly to the floor tubes 4' then to the-lower wall tubes 3'. thence to the roof tubes 2' and the top wall tubes 3 and finally to the outlet, which arrangement can be changed to suit the desired heating characteristics. Burners I, iire directly against the radiant bridgewall 6'.:-. Each combustion cone emanating from burners 5' moves in a'dire'ction such that its sides are substantially parallel with the slanting roof tubes 2' and slanting floor tubes l.

tubes 273, and 4' at an angle tending to provide even heat. distribution around the tubes and between the different tubes. The flue gases pass under the suspended bridgewalls and up through the convection tube bank I to the stack I.

The concrete floor slab ll' sloping upwardly and outwardly from a central foundation portion to the end walls I1 is prevented from becoming overheated by being air cooled on the bottom side. The radiant bridgewalls 6' are cooled by air which enters at the bridgewall ends passing into the spaces within the walls and thence upwardly passing through the spaces 8a within the walls and exits from the walls around the I- beams 8' to the' atmosphere.

The large modern furnaces usually have a separate base or foundation for the flue gas stack and often the hot gases are conveyed some distance underground to the stack. It may be necessary to locate the stack at suiiicient distance to provide a working area around the furnace proper. While such stacks must of necessity begin, at ground level, the stack in this novel design rests upon and is supported by the furnace structure. Further advantages of this design are: (1) Less space required. (2) Lower draft loss because of duct elimination. (3) Less stack because of lower draft loss and because of the elimination of the stack section between furnace roof and ground. forcing steel required because of duct elimination. (5) Lower refractory maintenance because of duct elimination. (6) More heat absorbing surface can be placed in a furnace of the equivalent fire box volume. (7) The surface may be placed so that all tubes receive maximum benefit of the radiant heating surface. (8) No overhead or underground .flue gas ducts are required. (9) The furnace floor is air cooled reducing concrete foundation requirements. (10) The furnace structure may be used to support the flue gas stack. (11) Floor tubes are supported by beams of refractory material eliminating the use of alloy castings. 12) The bridgewall is air cooled and is free to move permitting higher operating temperatures and requiring less refractory material.

In this design, the floor coil is tilted toward the radiant bridgewall in order to secure optimum heat distribution on the tubes. Floor and roof tubes are each disposed in such a manner as to be approximately parallel with the sloping surfaces of the combustion cone emanating from the burner. Tubes disposed in a horizontal Plane which are not parallel to the combustion cone do not have this advantage. By disposing the tubes parallel to the combustion cone in this design, the allowable heat release per cubic foot of furnace volume is more than double that of the conventional furnace. The tubes in this design absorb heat from the fire box, with approximately the same efiiciency because the relationship between the tube heat absorbing surfaces and each cubic unit of the fire box volume is approximately constant throughout the radiant section.

It will be obvious to those skilled in the art that many variations and modifications in the constructional details may be made and yet remain within the intended spirit and scope of my invention. Materials of construction may be selected from among those commercially available and suitable for the purpose at hand.

One modification of my furnace includes a single unit installation in contrast tothe double (4) Less concrete and reinunit as hereinbefore described. A single unit may be composed of one fire box with itsbumers 5 as in Figure'l, roof tubes in a plane sloping upward and away, and floor tubes in a plane sloping downward and away from the burners 5', and wall tubes above and below the burners 6'. One double hollow bridgewall receive heat from the single fire box, while the convection tubes will be between the double hollow bridgewall and a back wall.- Thus the drawing of Figure 1 may be modified to illustrate this embodiment by merely removing the right hand fire box and replacin its hollow bridgewall by a single, simple refractory wall which extends from the base of the stack 1' to the floor of the furnace. The four main columns l4 and the two upper main I-beams 8' may be unchanged. These two I-beams may support the stack 1' as in Figure 1. In this single unit furnace there will be one fire box, and one suspended hanging bridgewall and a more nearly rigid refractory back wall. The convection tubes are situated in the volume between the one hanging bridgewall and the refractory back wall through which volume combustion gases from the single fire box passing under the lone hanging bridgewall pass upward to the base of the stack.

In either embodiment of my invention, wherein a self ventilating bridgewall is used, the ventilation through each of the spaces 8a. may be controlled or regulated by adjustment of bafiles I 8. These baffles merely slide horizontally to open fully, or to open partly the spaces on either side of the I-beam 8 to control the amount of cooling air escaping from each space 8a.

Having described my invention, I claim:

1. A tube heater comprising a central framework extending from a central ground base to the .top of said heater; a floor extending upwardly said bridgewalls being suspended solely from said cross beams, being unattached at their ends and spaced from said'floor sufficiently to allow gas passage therebetween and dividing said heater into two radiation sections and enclosing a conheater, whereby two walls are formed on opposite side of said vertical supportmembers, refractory sections fastened to said horizontal support member and connecting the two walls formed on said vertical support members whereby a continuous passageisformed through said vertical support and along the length of each bridgewall between said connected'oppos'itely disposed walls; baflie 'members slidably aflixed in the open upper end 1 of each said bridgewall, whereby the opening at the upper endof said bridgewalls can be controlled in size; a stack extending upwardly from and supported by said central framework and communicating with said radiation sections through said convection section and said spaces beneath said bridgewalls, said bridgewalls being expandible laterally and vertically; banks of heating tubes disposed within said radiation sections so as to be substantially parallel respectively to said roof assemblies and said sloping floor; a bank of heating tubes within said convection section; and burners mounted in said radiation sections and directed toward said bridgewalls.

2. A tube heater comprising a central framework extending from a ground base to the top of said heater; a floor extending upwardly and outwardly from said ground base to at least one side of said heater; a first wall extending upwardly from an outer end of said outwardly and upwardly extending floor; at least one cross beam laterally extending across said heater, spaced from the ends of said heater and attached to the upper portion of said central framework;

a roof assembly extending downwardly and outwardly from said cross beam to said first wall; side walls closing the otherwise unclosed sides of said heater; a bridgewall extending downwardly into said heater from each said cross beam, said bridgewall being suspended solely from said cross beam, extending the width of said heater, beingunattached at its ends and spaced from said floor sufficiently to allow gas passage therebetween and dividing a radiation section from a convection section, each said bridgewall being open at its upper end and comprising a plurality of perforate vertical support members rigidly affixed at their upper ends to one of said cross beams, a horizontal support member attached to the lower ends of said vertical support members, refractory sections fastened to opposite sides of said vertical support members and extending across said heater, whereby two walls are formed on opposite sides of said Vertical support members, refractory sections fastened to said horizontal support member and connecting the two walls formed on said vertical support members whereby a continuous passage is formed through said vertical supports and along the length of each said bridgewall between said connected opposite ly disposed walls; baflle members slidably ailixed in the open upper end of each said bridgewall, whereby the opening at the upper end of said bridgewalls can be controlled in size; a stack supported by said framework and communicating with said radiation section through said convection section and said space beneath said bridgewalls, each said bridgewall being expandible laterally and vertically; banks of heating tubes disposed within each said radiation section so as to be substantially parallel. respectively to each said roof assemblies and said sloping floor; a bank of heating tubes within said convection section; and burners mounted in said radiation section and directed toward each said bridgewalls.

LOUIS J. WEBER.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS Number Name Date 1,591,431 Nash et a1. July 6, 1926 1,901,970 Huff Mar. 21, 1933 2,029,293 Alther Feb. 4,1936 2,105,819 Parsons Jan. 18, 1938 2,105,821 Parsons Jan. 18, 1938 2,111,380 Barnes Mar. 15, 1938 2,129,900 Barnes Sept. 13, 1938 2,132,517 Reintges Oct. 11, 1938 2,134,000 Mayo Oct. 25, 1938 2,142,956 Schauble Jan. 3, 1939 2,149,831 Bergman Mar. 7, 1939 2,205,776 Hosbein June 25, 1940 2,229,253 Nash et a1. Jan. 21, 1941 2,326,473 Lyster Aug. 10, 1943 2,335,317 Sherman Nov. 30, 1943 2,528,564 Weber Nov. 7, 1950

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