US2338708A - Heater - Google Patents

Description

Jan. 1l, 1944. 1 B, BRAGG 2,338,708

HEATER Filed Dec, 28, 1939 INVENTOR ESA/E B. 3e/ 66 Patented Jan. 11, 1944 HEATER Leslie B. Bragg, Scotch Plains, N. J., asslgnor to Foster Wheeler Corporation, New York, N. Y.,

a corporation of New York Application December 28, 1939, Serial No. 311,254 2 Claims. (Cl. 122-356) This invention relates to heaters, and more particularly pertains to furnaces or heaters of the type employed for the generation of steam, the heating' of oil for distillation or cracking, and the like, in which a bridge wall divides the interior of the furnace or heater into a combustion chamber and a heating chamber, the arrangement ordinarily being such that gases from the combustion chamber flow over the top of the bridge wall and over groups or banks of heating tubes disposed within the heating chamber at the other side of the bridge wall.

Heretofore, bridge walls for heaters of this character have been relatively massive refractory structures, resting on deeply sunk concrete piers, and built up of firebrick and refractory tile to the desired height above the furnace floor. This construction is costly both from the standpoint of installation and maintenance. Due to the high temperatures to which these walls are directly exposed and to the corrosive effect of the furnace gases frequent repairs are necessary, and since it is not unusual for the bridge walls to be several feet in thickness they occupy an undue amount of furnace space. Moreover, it is frequently necessary to provide special air cooling ducts or channels within the body ofthe bridge wall to prolong the life of the refractory.

The present invention overcomes these disadvantages and provides a bridge wall of reduced size, and of simpliied and improved construction, whereby the is very materially reduced, and the overall width of the setting is reduced without reducing the furnace volume. f

The invention will be understood from the following description considered in connection with the accompanying drawing forming a part thereof, and in which the single figure is a more or less diagrammatic vertical sectional view of a tubular oil still embodying the invention.

Referring to the drawing, the oil still shown comprises a furnace setting which is generally rectangular in horizontal and vertical cross-section, and includes side walls I and II, an end wall I2, a similar opposite end wall not shown, a roof I3, and a floor Il. In the lower portion of side wall II and adjacent the door is an outlet flue I5. The setting is divided into a combustion chamber I6 and a heating chamber I1, by means of a vertical bridge wall which comprises cost of installation and upkeep` heat resistant material, which is coextnesive or substantially coextensive with the tubes I8, and may' be in contact with these tubes or slightly spaced therefrom, and is disposed on the heating chamber side of the tubes I8. This plate prevents gas leakage between the tubes into the heating chamber, and provides in combination with the tubes a rugged wall structure capable of readily withstanding high furnace temperatures. The bridge wall extends longitudinally of the still at right angles to, and between, the end walls thereof. 'I'he combustion chamber I6 is fired by one or more fuel burners 2l, and combustion gases from the chamber I6 pass over the top of the bridge wall and flow downwardly through the heating chamber I1 to outlet ilue I5. Suitable means will be provided for the support of the tubes I8 and the backing plate I9.

Within the heating chamber I1 is a bank of horizontally disposed heating tubes 2l which are supplied with oil to be heated through inlet connection 22. By means of suitable headers or return bends, not shown, to which the adjacent ends of the tubes 2| are connected, the'oil flows upwardly through the tubes in heat exchange relationship with the heating gases passing downwardly through the heating chamber. From the tubes 2| the oil flows through conduit 23 to a group of heating tubes 2l which are disposed directly beneath the roof I3. From the roof tubes, the oil flows serially through a third group of horizontally disposed radiant heat absorbing heating tubes 25 which line the inner surface of side wall I0. From the bottom row of the tubes 25, the heated oil is conveyed by conduit 26 to the top row of the bridge wall tubes I8 through which the oil flows downwardly from row to row thereof to outlet 21 adjacent the bottom of the wall. The adjacent ends of the tubes IB are provided with suitable now connecting devices so that the oil will flow serially from one tube to the next adjacent tube, and similar flow connecting devices are provided for the ends of the roof tubes 24 and the wall tubes 25.

The bridge wall backing plate I9 is in heat exchange relationship with the tubes I8 and will be prevented from overheating by these tubes. Adequate means are provided for relative expansion or contraction of the tubes and the backing a vertical row of closely spaced or tangent, horizontally disposed tubes I8, and an adjacent relatively thin or light weight, heat resistant backplate, and for retaining the proper relative positions of `the tubes and backing plate so as to form a solid, leak-proof, fluid cooled structure. If desired, the backing plate may be composed of a plurality of sections secured together.

ing plate I9 of metal such as steel, or of other From the ioregoing,itwi1lbe apparent that the through the tubes of the bridge wall may be in l series, or in parallel, or a combination of series and parallel flow, and cold uid may be introduced into these tubes, or these tubes may be disposed at any desired point in the circulating system.

Since changes may be made in the particular form, location and arrangement oir the several parts of the bridge wall without departing from the principles of the invention, it will be understood that the invention is not to be limited excepting by the scope of the appended claims.

What is claimed is:

l. A furnace for heating hydrocarbon oils comprising a setting having enclosing walls forming an enclosure substantially rectangular in cross` section, a plurality of straight, substantially horizontal wall tubes extending adjacent and along at least one of the enclosing walls, a substantially vertical bridge wall comprising a plurality of closely adjacent, straight, substantially horizontal tubes connected at their ends for the passage of oil therethrough, the tubes of the bridge wall being in communication with the said wall tubes, said bridge wall tubes extending between oppositely disposed vertical walls and from a horizontal wall adjoining said oppositely disposed vertical walls to a point short of the horizontal wall opposite said adjoining horizontal wall, the bridge wall dividing the enclosure into a combustion chamber and a heating chamber, means for producing a stream of products oi' combustion in the combustion chamber, a metallic backing plate positioned adjacent the tubes of the bridge Wall on the heating chamber side thereof to prevent the passage of gases through the wall, and a bank of tubes adapted to receive oil to be heated disposed in the heating chamber, said tube bank being in communication with the wall tubes, the arrangement being such that the oil after being. heated in the tube bank is passed into said wall tubes whence it nows into and through the wall tubes extending between oppositely disposed vertical walls and from the horizontal bottom wall upwardly to a point short of the horizontal top wall, the bridge wall dividing the enclosure into a combustion chamber and a heating chamber, means for producing a stream of products of combustionl in the combustion chamber, a relatively thin metallic backing plate positioned adjacent the tubes or the bridge wall on the heatingv chamber side thereof to prevent the passage of gases through the Wall, an outlet for the products of combustion positioned at the bottom of the heating chamber, and a bank of tubes adapted to receive oil to be heated disposed in the heating chamber in the path of ilow of the products of combustion to said outlet, the tube bank being in communication with the tubes in the bridge wall, the arrangement being such that the oilafter being heated in the tube -bank is passed into said wall tubes whence it flows into and through the tubes oi the bridge wall.

LESLIE B. BRAGG.

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