US2122035A - Tube heater - Google Patents

Description

Patented June 28, 1938 UNITED STATES" PATENT osFica v TUBE HEATER Godfrey W. Larson, Kansas City, Mo., assignor to Standard Oil Company, Chicago, 111., a cor poration of Indiana I Application December so, 1933, Serial No. 704,803

12' Claims. (c1. 122-356) This invention relates to improvements in tube heaters, particularly tube heaters for use in the cracking and/or non-cracking distillation of petroleum oils. More particularly it relates to improvements in the arrangement of tubes, especially floor tubes within avtube heater having a radiant section and a convection section.

It is known to use one or more banks of tubes located at or near the floor of the so-called radiant section of a tube heater and it is known. that-this practice has many advantages, one of the most important of which is increased thermal efficiency. It is anobject of myinvention to increase this thermal efflciency by an improved arrangement of the floor tubes. Other objects of my invention are to reduce convective action in the radiant section, provide streamline flow and avoidlocal overheating. Further and more detailed objects will become apparent as the description proceeds.

I have illustrated my invention in the drawing in which:

Figure 1 is a schematic cross-sectional eleva- 4 tion of a tube heater embodying my invention;

"and,

Figure 2 is a schematic cross-sectional elevation of a tube heater embodying a modified form of I my invention. 1

Referring-now more particularly to the drawving, II is the radiant section and I2 the convectionsection of a tube heater comprising side walls I3 and I4, roof l5 and floor l6. A suitable,

fuel such as gas, oil or powdered coal is intro- -duced. through one or preferably a series of ports |'I, located near the bottom of side wall l3, by

means of burners I8 controlled by valves is.

The flame from burners 8 proceeds generally upward and across radiant section II as indicated by lines 20 and the combustion gases pass over bridge wall 2|, down through convection section 2 and out at 22 to a stack not shown.

The fconventional floor tube practice in the past has been to-place these tubes in a horizontal row along the conventionr l, horizontal floor I6 (Figure l) in radiant section II.

thermal efllciency since those floor tubes nearest bridge wall 2| are much further from flames 20 do those floor tubes nearest wall; [3. particularly important in large heaters since the than those floor tubes nearest wall I3. In other words, those flo'or tubes nearest bridge wall 2| in the conventional arrangement have a much smaller projected area as viewed from the hot spot? or center of heat of radiant section II than Thisis tween the various floor tubes 23.

I flnd, however, .that this results'in poor heat pick-up or stack effect of the hot gases in the radiant section pulls" the flames upward resulting in a higher hot spot and a lower heat pick-up in the floor tubes nearest the bridge wall.

I have remedied this defect by inclining-the 5 plane of the floor tubes 23 upward towards bridge wall 2| insuch a manner that the axes of the various 'floor tubes 23 are substantially equidistant from flames 20 or the edge thereof. In Figure lthis is done by inclining the plane 1 of the floor tubes, the imaginary line ,2! connecting floor tubes 23 and perpendicular to them being a straight line. In Figure 2 the imaginary line 24 conforms still more closely to the shape of flame 20, the shape of line 24 in this case the flame also serves to protect the bridge wall 2 tubes.

Alternatively, a cheaper construction can be'used consisting of a stepped-construction ZSadjacent .to bridge wall 2| as shown in Figure 1 or throughoutthe whole length of floor l6.

Under certain circumstances, as for example,

when powdered coal is employed as fuel it may be advantageous to build the floor entirely in a horizontal plane or alternatively to build the floor to function as an ash pit or sump. Any

of these modifications may be employed without departing from the spirit of my inventions.

It is to be understood that many different routings' of oil or other fluid to be heated through a tube heater embodying my invention can suit ably be useddepending on the results desired to 40 be accomplished. In the drawing the fluid to be heated enters-at 26 and passes back and forth through the lower bank of convection tubes A, the cold fluid thereby picking up the last avail-- able heat from the hot combustion gases leaving the tube heater. The partially heated fluid passes out at 21 and thence to bank B composed of floor tubes 23. After passing back and forth through floor tubes 23 the fluid passes to bank C composed of tubes mountedadjacent to bridge wall 2| ,and wall l3. The tubes in bank 0 are preferably arranged so that the fluid passes around radiation space H first through a tube adjacent wall 2| and'then through a tube adjacent wall 13. vFro n bank C, the fluid under- H and avoids local overheating which 9 going heating passes through line 28 to roof tube bank D, shown as a double bank. After passing back and forth through the tubes of bank D the fluid passes through line 29 to upper convection section bank E and thence out at 30.

Conventional headers are used to connect the various tubes.

Alternatively the fluid to be heated could be passed through floor tube bank B first, thereby protecting these tubes against overheating or through floor tube bank B last, thereby heating the fluid to a higher temperature. be omitted and many other modifications are possible.

A similar but generally lesser advantage can be obtained by arranging the roof tubes or other tubes located above the flames to conform to the shape of the flames in the same manner as shown for the floor tubes.

It will be noted that the floor tubes are ar-- ranged transverse to the direction of travel of the flames. This is 'highly preferable to arranging them parallel to the flames since in an ordinary radiant section the tubes can thus be made to conform to the shape of the flames without using.

curved tubes and the tubes are made readily accessible by the use of conventional headers.

While I have shown and described my invention in connection with certain specific embodiments thereof, I do not mean to be limited thereby but only by the scope of the appended claims.

I claim: 1. A tube heater comprising a radiant section, a convection section, a bridge wall disposed between said radiant section and said convection section, at least one fuel burner entering said radiant section nearthe bottom thereof and opposite said bridge wall, the flames from said at least one burner passing generally upward and across said radiant section towards the top of said bridge wall, and a row of heating tubes disposed generally below said flames and tilting upwards toward said bridge wall, the floor of said radiant section being disposed immediately below and substantially parallel to said row of heating tubes.

2. A tube heater comprising a radiant section, a

convection section, a bridge wall disposed between said radiant section and said convection section, at least one fuel burner entering said radiant section near the bottom thereof and opposite said bridge wall, the flames from said at least one burner passing generally upward and across said radiant section towards the top of said bridge wall, and a plurality of heating tubes arranged approximately transversely to the direction of flame travel in a bank disposed generally below said flames and tilting upwards towards said bridge wall.

3. A tube heater according to claim 2 in which the floor of said radiant section is stepped upward adjacent to said bridge wall to levels immediately below the corresponding levels -of said heating tubes.

4. A tube heater comprising a radiant section, a convection section, a bridge wall disposed between said radiant section and said convection section, at least one fuel burner entering said radiant section near the bottom thereof and opposite said bridge wall, the flames from said at least one burner passing generally upward and across said radiant section towards the top of said bridge wall, and a plurality of heating tubes'arranged approximately transversely to the direction of flame travel in a bank disposed generally below Bank C can said flames and conforming generally to the shape of said flames.

5. A tube heater according to claim 4 in which 6. A tube heater comprising a radiant section, a convection section, a bridge wall disposed between said radiant section and said convection section, at least one fuel burner entering said radiant section near the bottom thereof and opposite said bridge wall, the flames from said at least one burner passing generally upward and across said radiant section towards the top of said bridge wall, and a plurality of heating tubes arranged approximately transversely .to the direction of flame travel in a bank disposed generally below said flames and lying in a substantially hyperbolic surface conforming generally to the shape of said flames.

7 s A tube heater comprising a radiant section, a convection section, a bridge wall disposed between said radiant section and said convection section, at least one fuel burner entering said radiant section near the bottom thereof and opposite said bridge wall, the flames from said at least one burner passing generally upward and across said radiant section towards the top of said bridge wall, and a plurality of heating tubes disposed generally below said flames with their axes approximately equidistant from said flames and approximately transverse to the direction of flame travel.

8. A tube heater of the open flame type comprising a burner and heatingtubes disposed transversely to the direction of flame travel and arranged in a bank conforming approximately to the shape of the underside of the flame, said bank rising in a direction away from said burner from a level immediately below the level of said burner to a level above the level of said burner,

9. A tube heater comprising a radiant section, a convection section, a bridge wall disposed between said radiant section and said convection section, at least one fuel burner for said radiant section near the bottom thereof and opposite said bridge wall, the gases from said at least one burner passing generally upward and across said radiant section towards the top of said bridge wall, and a row of heating tubes disposed generally below said gases and tilting upwards toward said bridge wall, the floor of said radiant section being disposed immediately below and substantially parallel to said row of heating tubes.

rection of gas travel in a bank disposed generally .leastonebumer passing generally upward and erally upward and across said radiant section,.

across said radiant section towards the top of said bridge wall, and a plurality of heating tubes disposed generally below said gases with their axes approximately equidistant from said gases and approximately transverse to the direction of gas. travel.

l2. Aitube heater comprising a radiant section, a convection section, at least one fuel burner for said radiant section near the bottom thereof, the gases from said at least one burner passing genand a plurality of heating tubes disposed in a row generally below said gases with their axes approximately equidistant from said gases and approximately transverse to the direction of gas travel, the floor of said radiant section being disposed immediately below and substantially parallel to said row of heating tubes. v

GODFREY W. LARSON. 10

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