US2902981A - Vertical tube furnace - Google Patents

Description

Sept. 8, 1959 J. w. THROCKMORTON- ET AL 2,902,981

VERTICAL TUBE FURNACE 2 Sheets-Sheet 1 Filed Sept. 20, 1957 INVENTORS Sept. 8, 195 9 .1. w. THROCKMORTON ETAL 2,902,981

VERTICAL TUBEFURNACE Filed Sept. 20, 1957 2 Sheets-Sheet 2 INVENTORS Lu 2,; JUH/V W THAUC/(MOKTO/V ATTOKA/f/ United States Patent Ofiice 2,902,981 Patented Sept. 8, 1959 VERTICAL TUBE FURNACE John W. Throckmorton and John S. Wallis, New York,

N.Y., assignors to Petra-Chem Process Company, Inc'orporated, New York, N.Y., a corporation of Dela" ware Application September 20, 1957, Serial No. 685,152

2 Claims. (Cl. 122-356) This invention relates to vertical tube heaters which are particularly adapted for very large capacity and in which the fluid to be heated may enter the heating tubes at temperatures as low at 400 F., for example, and in which the desired outlet temperature from the radiant zone of the heater is at relatively high temperature such as, for example, between 1400 to 1500 F.

One object of our invention is to have one bank of tubes in the radiant zone where the fluid temperature is relatively low exposed to direct radiation from the burners on one side and one bank of tubes in the radiant Zone where the fluid temperature is relatively high exposed to direct radiation from the burners on both sides.

Qther objects and advantages of this invention will be apparent from the following description and drawings showing certain embodiments of this invention, and from the appended claims.

Referring to the drawings:

Figure 1 is a partially sectional elevation of a vertical tube heater embodying this invention.

Figure 2 is a sectional plan view taken on the line 22 of Figure 1.

Figure 3 is a detailed elevation on a larger scale illustrating one pair of heating tubes with a bottom guide and top supports.

Figure 4 is a sectional plan view on the line 44 of Figure 1.

Figure 5 is a plan view on a larger scale taken on the line 5-5 of Figure 1.

Figure 6 and Figure 7 show on a smaller scale diagrammatic modifications which also embody this invention, these views corresponding generally to the sectional plan view of Figure 5.

With special reference to Figs. 1 to 5, inclusive, the heater illustrated comprises an upright cylindrical furnace shell 10, preferably formed of steel plate lined with a refractory or other suitable heat insulating material.

The furnace shell 10 is supported by a plurality of structural beams 11, only two of which are shown in Fig. l, which extend to the top of the furnace shell and project downwardly to the foundation 12 so as to support the shell and its bottom plate 13 at a sufficient height above the foundation to enable operators to have easy access to the bottom of the heater and to the burners 14 and 15 which are mounted therein. The bottom plate 13 is provided with a door 16, which may be square as shown in Fig. 5, and provides access to the interior of the furnace.

An annular bridge wall mounted at the top of the furnace shell 10 supports a square box 21. A plurality of brackets 22 are mounted upon and circumferentially spaced around the top of the furnace shell 10. A stack 23 is mounted on the brackets 22.

As shown in Fig. 5, the burners 14 are mounted in the form of a circle concentric with the cylindrical furnace frame and approximately half way between the inner wall of the cylindrical furnace and the axis.

The burners 15 are also arranged in a circle but are spaced approximately half way between the burners 14 and the wall of the cylindrical furnace. They are also spaced circumferentially a suificient distance to permit certain of the heat exchange tubes to be installed between them, as hereinafter described.

While the heater described may be utilized for various sizes and capacities, it is being built for commercial use with an inside diameter of the furnace shell of over 30 feet and with a height from the foundation to the top of the box 21 of approximately feet.

Within the furnace a large number of vertical tubes 30 are located, spaced from but close to the inner insulating wall of the furnace shell.

Additional tubes 31 are arranged in radial banks between the bumers 15, as shown in Fig. 5. The tubes are interconnected at the bottom and top by the usual return bends and, as shown in Fig. 3, the return bends 32 are used to connect the tubes 31 to each other and to the tubes 30 so as to form a desired number of coils. The tubes are supported laterally at the bottom by lugs 54 which extend into holes 55 in the bottom plate 13 of the furnace. All of the tubes are suspended from the bridge wall 20 by hangers 56 which are connected to suitable lugs 57 mounted on the return bends at the top or on the L connections as shown in Fig. 3.

As shown in Fig. 5, for example, there are 18 coils, each made up of four wall tubes and two radial tubes. Each coil has an inlet connection at the top of the furnace, as shown in Fig. 5, which connections are designated 33. Each inlet is connected through valve 34 and jumper 35 to one bank 36 of a preheating coil 37. The preheating coil 37 is made up of 18 vertical banks, as shown in Fig. 4, and each bank is connected to a fluid inlet manifold 40.

The fluid flows from the manifold 40 in multiple paths through the 18 banks of the preheating coil 37 and into the several coils of large tubes which are interconnected, as already described, and the innermost radial tube of each coil is connected as shown in Fig. 1 by connections 41 which extend upwardly inside the throat of the heater within the bridge wall 20 and radially inward to a large manifold 42.

The connections 41 of adjacent coils enter the mani fold 42 at two different levels, asshown at 43 and 44 of Fig. 1. This enables the tube ends to be connected to the central manifold without crowding, as shown in Fig. 2.

Mounted within the furnace at the top and extending more than a third of the way from the top to the bottom of the furnace is an inverted cone baffle 50, which is suspended by hangers 51 from the bridge wall 20.

When the furnace is in operation, the oil, gas or other fluid to be heated is introduced through inlet pipe 52 into the manifold 43, thence it flows through the flat coil banks 36 of the preheating coil 37. From each bank 36 the fluid flows through its connector 35, valve 34, connector 33 and into the inlet pipe of one of the main coil banks, which is composed of four wall tubes 30 and two radial tubes 31, and thence through internal connections 41 to the manifold 42, and is discharged out of the pipe 53. The fluid to be heated flows first through the wall tubes, then through the radial tubes, which are subjected to high temperature.

The burners 14 produce high temperature flame and hot gases which pass upwardly through the furnace in an axial direction. The burners 15 also produce hot flame and gases which pass upwardly through the furnace in an axial direction, with the result that radiant heat is supplied very directly to the wall tubes on their inner faces and is reflected to the back of the wall tubes by the insulating wall of the furnace shell 10.

The radial tubes 31 are arranged in staggered relation, as shown in Fig. 5, so that they receive direct heat by radiation: on both sides from the two adjacent burners between'w-hich they are located.

The tubes in the radial banks, which for convenience have been referred to as radial tubes, may be made of special alloy metals, since. the fluid. has been: raised in temperature in passing through the preheating; coil 37 andthroughthe wall tubes 30 before the fluidreaches the radial tubes 31-;

The upper ends of the tubes are also heated to some extent* byconvection; because" theconical bafil'e' 50 re-' flects-thehot gases; which have already given'up part of their heat to-the fluid in the tubes, against the upper ends of the tubes, from thence the hotgases pass within the annular bridge wall 26 andfl'ow over theconnections Referring particularly to' Fig; 6, instead of providing 18 coils; the'heater may be divided, for example, into four coils-each composed of 12' wall tubes and 3 radial tubes, and a' single burner 60" may be substituted for burners 1*4 andthe four burners 61 may be substituted for the burners 15. The arrangement may be still further modified; as shown in Fig. 7, by using a singlecentral burner 65' and a ring of burners 62', two of' which are located between each adjacent group of radial tubes.

It is evident that further modifications maybe made within the spirit of this invention, and the number of coils'andthe arrangement will depend on the fluid to be heated, the size of the furnace, as well as numerous other factors, so that only such limitations should be imposed as are indicated in the appended claims.

What we claim is:

1. An upright furnace having a relatively tall cylindrical shell, a-flue gas exit at the top, a heat reflecting inner wall, a bottom plate, a plurality of radial banks of heat exchange tubes extending vertically from top to bot-tom of the furnace shell, said radial banks extending radially less than half the distance from the furnace wall 4* 7 toward the central axis of the furnace, a plurality of circumferential banks of heat exchange tubesextending from top to bottom of the furnace shell located between said radial banks near the furnace wall and spaced therefrom, said circumferential banks together constituting a single cylindrical row of heat exchange tubes spaced from the furnace wall and equally spaced from each other, upshot central burners-mounted in the bottom plate near the axis to discharge a column of flame and hot gases within the open central space ofth'e' furnaceand an outer ring of upshot burners severally located to discharge flame and hot gases upwardly in the spaces between the axial tube banks.

2. An upright furnace having a. relatively tall cylindrical shell, a flue gas exit at the top,, a heat reflecting inner wall, a bottom plate; a pluralityof radial banks of heat exchange tubes extending vertically from top to bottom of the furnace shell, said radial banks extending radially less" than half the distance from the'furnacewall toward the central axis of the furnace; a plurality of=circumferential banks of heatexchange tubes extending from top to-bottomof the furnace shell located between said= radial banks near the furnacewall and spaced therefrom, said circumferential banks together constituting a single cylindrical row of heat exchangetnbes' spaced from the furnace wall andequally spaced frorrr each other; means for connecting each of the circumferentialtube banks with an'adjacent radial bank at one end' toform a'plural ity of coils composed ofone-circumferenti'al an'd at*least-" one radial tube bank; upshot central burners'mountedin the bottomplate near the axis'to' dischargea' COIUHHI of flame and hot gases within the'op'encentral space' of the furnace, and an outer' ring' of upshot burners severally Wasp et: a1. A Dec. 1, 1953 UNITED STATES PATENT OFFICE CERTIFICATE OF CORRECTION Patent No. 2,902,981 September 8, 1959 John W. Throckmorton et al.

in the printed specification It is hereby certified that error appears ion and that the said Letters of the above numbered patent requiring correct Patent should read as corrected below.

Column 4, lines 13 and 35, strike out "axial", each occurrence, and

insert instead radial Signed and sealed this 15th day of March 1960.

(SEAL) Attest:

KARL H. AXLINE ROBERT C. WATSON Commissioner of Patents Attesting Oflicer

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