US2000376A - Heating apparatus - Google Patents

Description

y 1935- E. .L. CARGILL ET AL' I 2,900,376

I HEATING APPARATUS V 7 Filed May 10, 1935 2 Sheets-Sheet 1 x FlG.1-.

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HEATING APPARATUS Filed May 10, 1953 2 Sheets-Sheet 2 INVENTORS EUGENE L. CAPG/LL dOHNABAST/ON ATTORNEY Patented May 7, 1935 Q UNITED STATES PATENT OFFICE HEATING APPARATUS Eugene L. Cal-gill and John A. Bastion, Dallas, Tex., assignors to The Texas Company, New York, N. Y., a corporation of Delaware Application May 10, 1933, Serial No. 670,230 4 Claims. (01. 122-338) This invention relates in general to furnaces defined by suitable side, top and bottom walls; and more particularly to an improvement in heat the side wall being indicated by the numeral 2, distribution therein. the top wall by the numeral 3 and the bottom wall In vertical tube furnaces of the type wherein by thenumeral 4. A lining 5 of insulating ma- 5 the tubes are adapted to be heated substantially terial in the nature of suitable refractories may 5 entirely by radiant heat, even heat distribution be provided for protecting the side walls 2 and throughout the entire lengths of the heat abthe bottom wall 4. While a lining is shown as sorbing tubes is of paramount importance. being appliedvto the side and bottom walls, it is Many furnaces of this type have been installed to be clearly understood that it might also be having heat producing means, in the nature of applied to the top 3. 10 suitable burners, located on a level with the lower A plurality of burner ports 6, equally spaced portion of the vertical heat absorbing tubes. In around the center of the bottom of the furnace firing a furnace of this type, the flame streams in a ring or circle; may be provided for receivfrom the individual burners-are projected uping suitable burners I positioned in each. The

' .5 wardly and radiate heat, without flame impingeburners I may be supplied with any suitable type ment, to the vertical heat absorbing tubes. of fuel, such as liquid, gas or solid fuel, with With the burners positioned on a level with the necessary air to aid combustion being adthe lower ends of the vertical heat absorbing mitted in any suitable manner through the burntubes, the lower portions of the tubes may not er ports 6. A single supply pipe may feed the receive the same intense radiant heat as higher fuel to the burners. As will be noted from Fig- 20 portions. This may be due to the incomplete ure I, the burners are adapted to direct the initial combustion of the fuel at the mouths of flame stream from each upwardly to distribute the burners and also for a distance thereabove the heat produced by each throughout the length w h limits h a radiation from the flame in of the combustion chamber. The hot gases rethis particular section of incomplete combustion. sulting from the combustion of the fuel pass up- 25 I In accordance with this invention more heat wardly through a suitable insulated flue 8 to a may be applied t th ottom p ti s of the stack 8" from which they are conducted to the tubes t an in the past in O de to more v nly atmosphere. If desired, suitable means may be distribute the heat throughout the length of tubes provided in the stack a for utilizing any e thereby increasing the overall operating efiiciency ing t in t flue gases For instance, an u- 30 of the furnace and avoiding any possible overpreheater and/or an ec'onomizer may be p051 heating of the upper portions of the tubes. The tioned in the stack a' inYention may be by pfimtioning A plurality of vertical heat absorbing tubes 9 suitable heat radiat ng and reflecting surface may be positioned within the combustion Chaim m the burner rmg notmauy'employed for her I and are adapted to be heated substantially 35 heating the furnace. In this manner heat may entirely by radiant t produced by the upberadlated as well as deflected to the lower wardly projecting flame streams from the portmn of the tubes rality' of burners. The heat absorbing tubes 9 In order to make the mventlon more clearly may pass through both the and bottom walls 40 understood there is show-n m the accompanying of the combustion chamber and maybe connected 40 drawing, means for carrying the same into practi by suitable return bends II). In order to avoid cal effect without llmiting the improvements in fin of the fluid mg through the return their useful applications tovthe particular strucg pass bends Ill, suitable means may be provided. As

ture, which, for the purpose of explanation, has shown the return bends m may be located in been made the sub'lect of Illustration heat insulating chambers ll positioned exterior Figure 1 is an elevational view, partly in secwing ma dyin of the combustion chamber l. The chambers ll tion sho a vertical I ce embo 8 my may be provided with removable covers l2 to m 'g i a i in plan, taken a1ng lines permit ready access thereto. The same type of 2-4 of Figure 1. insulated chambers may be provided for bo 50 Referring to the drawings wherein the same the upp r andrlower return bends. parts are represented by like characters through- The furnace proper m y be s pp rt d by slutout the views, and more particularly to Figure 1, able standards I! restmgupon a base ll. Addithere isshown a furnace having a combustion tional standards I! may be provided for the fur-- '55 chamber]. The combustion chamber l may be nace, these-standards lending additional support tothe bottom of the furnace in which the burners are installed.

In the past it has been customary to fire a furnace of the type described by projecting the flame stream from each burner upwardly in an unobstructed path. With this method of operation, the flame stream from each burner projecting upwardly passes through a relatively short distance before complete combustion thereof is obtained. Without complete combustion of the flame stream at the beginning thereof, the maximum heat intensity is not obtained resulting in less heat being radiated to the lower portions of the heat absorbing tubes 9 than to other portions thereof, thereby resulting in possible overheating of the upper portions of the tubes. In accordance with this invention, the lack of intense heat to the lower portions of the tubes is obviated and the entire face within the ring or circle defined by the plu-.

rality of burners. As shown in Figure 1, a heat radiating and reflecting surface l6 corresponding in shape to the shape of the combustion chamber may be provided. The heat radiating and reflecting surface l6 may consist of a plurality of refractory bricks N suitably cemented together to provide an inner cylinder within the combustion chamber. In constructing the refractory wall, the bricks I! may be arranged so that every other course thereof is a header course, in other words, the courses may alternate between header and stringer courses.

As shown in the drawings, the refractory wall inside of the ring or circle defined by the plurality of burners does not extend very high into the combustion chamber. It has been found that in operating a furnace of the type described in which the combustion chamber has a height of about 30 feet, more or less, the refractory wall will produce satisfactory and. unexpected results if only constructed to a height of about 6 to 8 feet. The diameter of the refractory surface within the combustion chamber is likewise smaller in comparison with the diameter of the combustion chamber proper and if the diameter defined byface of about 4 or 5 feet in diameter.

While certain dimensions have been set forth that may advantageously be employed in constructing a furnace in accordance with the invention, it is to be clearly understood that these are merely for the purpose of explanation and may be varied without departing from the spirit or the scope thereof. For instance, compressed air 'may be utilized in aiding combustion which would decrease the distance through which the flame streams project before complete combustion, or, if desired, a special type of burner may be employed to obtain rapid complete combustion. The invention may be applied to a furnace of the type described operating in-any manner, the particularsize and shape of the refractory wall depending upon the particular operating conditions and size and shape of the furnace proper.

In lieu of cementing the bricks ll tightly together in order to form a solid refractory wall, the individual bricks may be arranged in a checkerbrick work manner.. By this arrangement, it will be possible to cut down the cost of the refractory wall. If desired, an additional burner may also be provided and positioned within the refractory wall to increase the amount of radiation therefrom.

Any suitable type of refractory material, such as fire brick or the like, may be used. The invention also contemplates the use of any other suitable type of radiating and reflecting surface, such for instance, as metal or metal alloys. Any suitable metal or alloy may be employed, but it is preferred to use one which satisfactorily resists corrosion and oxidation, such as chromium and/or its alloys.

In operating the improved furnace, the flame streams from the burners project upwardly and the distance through which they may be projected before complete combustion will vary depending upon the type of burners employed and the amount of air used to aid combustion. The burners, as shown in the drawings, being closer to the refractory material comprising the wall than the heat absorbing tubes, heat it to a greater extent. The upper portion of the wall is heated to a greater extent than the lower portion which provides for additional heat being conducted from the upper to the lower portion of the refractory wall. The entire wall being intensely heated by the flame streams radiates heat to the lower portion of the heat absorbing tubes in proximity thereto thereby increasing the heat input to the tubes. Moreover any impingement of the flame and hot products of combustion against the refractory wall aids complete combustion of the fuel and results in the hot products being deflected outwardly towards the lower portion of the tubes thereby also providing additional heat. If desired, the refractory wall may be flared outwardly from the bottom thereof to a slight extent in order vto provide for additional heat deflection.

The hot products of combustion after passing through the section of the combustion chamber provided with the heat radiating and reflecting surface are merged and extend through the remainder of the combustion chamber in a column of substantially uniform cross-section. The column of hot products of combustion evenly radiate heat to the tubes surrounding it thereby evenly heating the fluid passing through the tubes preponderantly by radiant heat.

While there is shown and described a furnace of circular cross-section, it is to be clearly understood that the invention is not limited to a furnace of this particular shape, as it' will be obvious to those skilled in the art that the invention is applicable to a furnace of any particular shape. Moreover, the invention is applicable to a furnace in which the flame is projected downwardly from the top thereof.

From the foregoing it will be apparent that this invention makes possible the operation of a vertical tube furnace in such a manner as to evenly distribute the intense radiant heat 'to the entire length of the heat absorbing tubes. By evenly distributing the heat to the heat absorbing tubes, local overheating is obviated and more rapid and even heatingof the fluid passing through the tubes is accomplished. It has been found that in heating hydrocarbon oils passing through heat absorbing tubes in a furnace of the type described, it is possible to increase the throughput of the oil with as high a rate of heat input as in the past, which obviously affords a more efficient furnace structure.

While there isshown and described the preferred embodiment of the invention, it is to be understood that the invention is not confined to the precise details of construction herein set forth, 7;

by way of illustration, as it is apparent that many changes and variations may be made therein, by those skilled in the art, without departing from the spirit thereof, or exceeding the scope of the appended claims.

What we claim is:

1. In a furnace, a vertical combustion chamber, a plurality of burners positioned at the bottom of said combustion chamber. for producing hot products of combustion and directing them upwardly through the combustion chamber, a plurality of Vertical heat absorbing tubes extending from top to bottom of said combustion chamber and adapted to be heated throughout their length preponderantly by radiant heat from said'combustion products, means in the lower portion of said combustion chamber surrounded by the lower portion of said vertical tubes directly exposed to the hot products of combustion from each burner to absorb heat therefrom and radiate absorbed heat to said lower portion of the vertical tubes to increase the total heat input thereto, said means being free from direct association with fluid containing sources which would normally absorb heat therefrom and decrease the temperature thereof and extending within the combustion chamber for less than about half of the height thereof to thereby permit the combustion gases from each burner after being exposed thereto to be substantially completely combined thereabove to pass through the remainder of the combustion chamber in an unobstructed path to thereby heat the remaining portion of the vertical tubes preponderantly by radiant heat.

2. In a furnace, a vertical combustion chamber, a plurality of burners positioned at the bottom of said combustion chamber for producing hot products of combustion and directing them upwardly through the combustion chamber, a plurality of vertical heat absorbing tubes extending from top to bottom of said combustion chamber and adapted to be heated throughout their length preponderantly by radiant heat from said combustion products, a refractory wall in the lower portion of said combustion chamber surrounded by the lower portion of said vertical tubes directly exposed to the hot products of combustion from each burner to absorb heat therefrom and radiate absorbed heat to said lower portion of the vertical tubes to increase the total heat input thereto, said refractory wall being free from direct association with fluid containing sources which would normally absorb heat therefrom.

and decrease the temperature thereof and extending within the combustion chamber for less than about half of the height thereof to thereby permit the combustion gases from each burner after being exposed thereto to be substantially completely combined thereabove to pass through the remainder of the combustion chamber in an unobstructed path to thereby heat the remaining portion of the vertical tubes preponderantly by radiant heat.

3. In a furnace, a vertical combustion chamber, a plurality of burners arranged in a circle at at the bottom of said combustion chamber for producing hot products of combustion and directing them upwardly through the combustion chamber, a plurality of vertical heat absorbing tubes extending from top to bottom of said combustion chamber and adapted to be heated throughout their length preponderantly by radiant heat, a vertical refractory wall within the circle defined by the burners surrounded by the lower portion of said vertical tubes and directly exposed to the hot products of combustion from each burner to absorb heat therefrom and radiate absorbed heat to said lower portion of the vertical tubes to increase the total heat input thereto, said refractory wall being free from direct association with fluid containing sources which would normally absorb heat therefrom and decrease the temperature thereof and extending within the combustion chamber for less than about half of the height thereof to thereby permit the combustion gases from each burner after being exposed thereto to be substantially completely combined thereabove to pass through the remainder of the combustion chamber in an unobstructed path to thereby heat the remaining portion-of the vertical tubes preponderantly by radiant heat.

4. In a furnace, a vertical combustion chamber, a plurality of burners positioned on the bottom of the combustion chamber, a plurality of vertical heat absorbing tubes within said combustion chamber, the lower portion of which surround said burners, and means arranged closer to said burners than to said lower portion of the tubes adapted to absorb heat from combustion products from said burners and radiate absorbed heat therefrom to the lower portion of said vertical tubes, said means being free from direct association with fluid containing sources which would normally absorb heat therefrom and decrease the temperature thereof and affording a surface for at least partial impingement of the combustion products for up to about half the height of the combustion chamber to thereby effect more complete combustion thereof in the lower portion of the combustion chamber and permitting the combustion gases to be substantially combined thereabove to pass through the remainder of the combustion chamber in an unobstructed path to thereby heat the remaining portion of the vertical tubes preponderantly by radiant heat.

' EUGENE L. CARGILL.

JOHN A. BASTION.

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