US2094724A - Heater - Google Patents

Description

H. B. SHARP o ts,- 1937'.

HEATER- Filed NOV. 24;,1934 3 Sheets-Sheet 1 INVENTOR Howard 5.5/20.

ATTORNEY Oct. 5, 1937.

H. B. SHARP HEATER Filed Nov. 24, 1934 a Sheets-Sheet? Till/villi! all/4721A; Ell/ll N 4 VD Q 6 INVENTOR Howard B. 5/10, rp

ATTORNEY Oct. 5, 1937; H. B. SHARP 4,

' HEATER Filed Nov. 24, 1934 3 Sheets-Sheet 3 INVENTOR ATTORNEY Patented Oct. 5, 1937 UNITED STATES HEATER Howard B. Sharp, Independence, Mo., assignor to Standard Oil Company, Chicago, Ill., a corporation of Indiana Application November 24, 1934, Serial No. 754,642

6 Claims.

This invention relates to improvements in heaters, and more particularly heaters such as tube heaters or pipe stills commonly employed in the petroleum refining industry for heating or 5 cracking petroleum products.

It is customary, in the construction of heaters of the type described, to build a heater with a combustion chamber and one or more communicating convection chambers, which are separated from each other by a vertical wall or bridge wall, which serves as a screen against radiant heat but permits the passage of hot gases or hot products of combustion. For the most part, such heaters are built with a single combustion chamber and a single convection chamber. The fuel which is to be burned in the combustion chamber is usually introduced through burners in the wall oppositev the bridge Wallthis wall being generally termed the front wall, or the burners may also be placed in the side walls. The hot gases from the combustion of the fuel, thus introduced, flow inwardly and upwardly, thence over the bridge wall and thence downwardly through the convection chamber to a point adjacent the bottom thereof, whence they are discharged through one or more flues and thence permitted to pass to the stack. The oil to be heated is passed through tubes which are generally disposed adjacent the roof, floor, or Walls of the combustion chamber and also disposed in banks of tubes in the convection chamber, the tubes being usually horizontal and parallel to the bridge wall.

In the operation of such heaters it is frequently noted that the temperature of the gases at one side of the combustion chamber is very much higher than that at the opposite side and the zone of greatest heat intensity, sometimes called the hot spot, is disposed to shift from side to side in the combustion chamber. It is believed that this shifting of the hot spot in the combustion chamber is due to one or more of several factors, which include uneven firing, the effect of Wind on the exterior wall of the heater which causes air to leak through the intersticesof the brickwork, as well as to the stack effect, or draft. Actual observation on operating heaters indicates differences in temperatures of as much as 20% when measured along opposite walls of the combustion chamber..

Once the temperature in the combustion chamber becomes unbalanced it has been found to be extremely difficult to shift the zone of increased temperature to the central region of 3 the chamber, where it properly belongs. Moreover, where the unbalanced condition exists in the heater naturally the tubes adjacent one wall of the heater will tend to become overheated, While the tubes adjacent the opposite wall will be underheated. This results in improper heat- 5 ing, incomplete combustion, and inefiicient operation of the heater.

One of the objects of my invention is to provide means for controlling the location of the hot spot and for controlling the flow of hot gas through the combustion chamber and thence through the convection chamber so as to avoid overheating of the tubes and to cause uniform and economical operation of the heater at all times and under all conditions.

Another object of my invention is to provide an improved heater in which the proper temperature balance within the combustion chamber may be maintained and controlled without the necessity of continually manipulating and readjusting the burners used in firing the heater.

Attempts. have been made to preserve the heat distribution in the combustion section of a heater by controlling the distribution of gases flowing from the convection section to the stack by means of dampers in several flue openings adjacent the bottom of the convection chamber. Actual experience in operating heaters equipped with a plurality of flue outlets has shown that while the operation of such heater is an improvement over the operation of heaters equipped with but a single flue connection, nevertheless unbalanced temperature conditions and a shifting of the hot spot were experienced.

I have found that by subdividing the convection chamber into a plurality of zones, preferably by means of vertical walls disposed at right angles to the bridge wall and by providing each of these several zones with a separate flue opening equipped with a valve or damper, the temperature balance in the combustion chamber may be maintained very readily and the hot spot may be shifted at will.

My invention is illustrated in the following drawings which form a part of this specification and in which like elements are represented by identical reference numerals:

Figure 1 is a diagrammatic illustration of my improved heater, the drawing being in perspective with parts thereof being broken away.

Figure 2 is a diagrammatic plan View.

Figure 3 is a simplified plan view showing the gas flow under normal conditions in a heater of the prior art type.

Figure 4 is a simplified plan View of a prior art heater showing the unbalancing of the gas flow which results in such heater without the manipulation of any of the dampers.

Figure 5 is a simplified plan view of a prior art heater showing the gas flow which results when one of. the dampers in said heater is operated to shut off a fiue.

Figure 6 is a simplified plan View of my heater showing the gas flow which results under the same conditions which produce the unbalancing,

as represented in Figures 4 and 5 of the prior art,

heater.

Figure 7 is a shadow drawing in perspective of the prior art heater of Figure 5.

Figure 8 is a detailed sectional view showing a fragmentary elevation of one of the convection section partitions.

Figure 9 is a sectional View taken along the line 99 of Figure 8.

Figure 10 is another sectional view taken along the line !E|l0'of Figure 8.

Figure 11 is a perspective view of a modified type of convection section partitions.

Figure 12 is a sectional View taken along the line I2-l2 of Figure 11, and,

Figure 13 is another sectional view taken along the line i3l3 of Figure 11.

- Referring to Figure 1, I have illustrated therein diagrammatically a conventional type of heater having side walls BAE, front wall AEN, side wall NGI, and roof ABC, these walls being partly broken away and being the side wall, front wall, and roof, respectively of the combustion chamber; the floor of the combustion chamber is a surface EFGN. The bridge wall is represented by the plane HFGI; The floor of the convection chamber is represented by the plane JKML and the vertical partitions which divide the convection chamber into zones are represented by thev planes POQR and TSUV respectively. The rear wall of the convection chamber is represented by the plane BCLJ and this wall is provided'with' a plurality of orifices, one in each zone, and

numbered respectively I, 2,, and 3, the orifices being provided respectively with dampers 4, 5, and 6. r

, On referring to Figure 2, which is a plan View of my heater, there will be'found the front wall 8 and side walls 9 and [0 of the combustion chamber. The bridge wall l5 serves as the rear wall of the combustion chamber. Fuel nozzles l l introduce 'fuel for the purpose of combustion through the front wall 8. Oil-containing tubes l2, l3, and i4 are'disposed adjacent the side wall 9, bridge wall l5, and side wall In respectively. The convection chamber is provided with side walls I! and I8 and vertical partitions l9 and 20, through which convection tubes I5 are disposed, generally parallel to the bridge wall, having axes which are horizontal. .At the lower part of the rear wall of the convection chamber are flue connections l, 2, and 3, being provided with dampers 4, 5, and 6 respectively, the flue The diagrammatic showing of Figure 7 is similar to that of Figure 1, except that the heater is e that of the prior art type and does not include the vertical partitions which are shown in Figure l; the elements which are common to Figures 1 and 2 are given identical reference numerals.

In Figures 8, 9, and 10 I show'one type of construction of the vertical partitions which are employed to separate the convection chamber into zones. In this type of construction the partitions are formed of corrugated elements 3| and 32, constructed with a plurality of. ports IE to per- .mit the partition-to be pierced by the convection tubes 6. The assembled partition is maintained in vertical alignment by providing the bridge wall l5 and the opposite wall of the combustion chamber with recesses 33 and the upper edge of the partition is assembled by bolting together channels 30, this providing a fairly rigid type of construction which, at the same time, permits expansion of the elements of the partition and permits it .to accommodate the convection tubes It, even under the stress of great heat. In Figures ll, 12, and 13 I have illustrated a modified type of partition wall in which the partition is constructed of a single plate which is ierced to permit the'insertio'n of the convection tubes l6. Split'rings' ll are disposed around each tube and on opposite sides of the partition 40 the end of the partition may be guided in recesses 43 provided in the bridge Wall and the rear wall of the convection chamber. The split rings are preferably of heat resistant alloy and of sufficient size to' overlap the orifices in the plate 40 so as to establish a iairly gas-tight seal between the adjacent zones of the convection section, and so constructed'as to permit the rings to embrace the tubes and at the same time to permit the rings to expand, when the tubes expand, under heating; 7

- In operating my improved heater the position of the convection chamber is controlled by regulating the efiective area of one or more of the orifices l, 2, and 3, by means'of the respective dampers. This regulation may be illustrated by referring to Figures 3 to 6 inclusive of the accompanying drawings. In Figure 3, which shows the prior art type of construction without the items of my invention, under'perfect operating conditions, the hot spot, which is represented by the oval in the combustion chamber, is adjacent the center of the combustion section and slightly nearer the bridge wall. The hot gases fiowover the bridge wall in substantially uniform volume at all points, and thence flow down through the convection chamber. in substantially uniform volume and substantially equal amounts of hot gases will be discharged through the exit orifice at any given time. If however, the heater should be subjected to wind which approaches the heater from the direction adjacent the side wall 9, as shown in Figure 4, cooled air will penetrate the interstices between the brickwork of side wall 9, the hot spot will be shifted toward side wall IE], and because of the greater density of the cooler air adjacent side wall 9 more hot gases will flow over the bridge wall on the side toward side wall ID. This will tend to increase the volume of hot gases discharged through orifice 3 of the convection chamber and will diminish the volume of gas discharged to orifice I. i

If, in the prior art type of heater, it is attempted to rectify this condition of unbalance by closing oh the orifice 3by closing damper 6 and completely opening orifice I by opening damper 4, it is found that' the hot spot is not shifted in the combustion chamber and the same tendency to accumulate a greater volume of hot gases adjacent side wall I0 is experienced, both in the combustion chamber and after the gases flow over the bridge wall l5. This condition of unbalance continues, as illustrated by the arrows on Figure 7, until the gases have traversed downwardly through most of the convection chamber and it is only toward the low part of the convection chamber that the gases are drawn to the open orifices because of the stack effect or draft created by the stack.

Under the same conditions of wind adjacent the side wall 9, with my invention as illustrated in Figure 6 where orifice 3 is shut oiT by closing damper 6 and orifice l is opened by fully opening damper 4 there is no passage for the hot gases in the zone of the convection chamber adjacent the side wall 10. The hot gases in the combustion chamber, therefore, must pass over the bridge wall at points adjacent the two open zones controlled by orifices I and 2. More hot gases are therefore thrown adjacent side wall 9 and the hot spot is automatically shifted back to its central position in the combustion chamber. Under these circumstances the tubes containing the oil to be heated in the combustion chamber are uniformly heated and a balanced operation is maintained in the combustion chamber.

My invention overcomes a serious problem in maintaining the proper balance in the combustion chamber of a heater, which may be illustrated by the following data indicating the various conditions of temperature existing in a heater provided with 3 outlet orifices from the convection chamber, but not provided with the partitions which my invention contemplates. The temperatures given were taken at the center of the side walls which correspond to walls 9 and ID of the With the installation of partitions to divide the convection chamber and the zones, as contemplated by my invention, it is possible to maintain the temperatures on opposite side walls of the combustion chamber approximately the same at all times. I may also make the operation of the control dampers automatic in response to temperatures measured by thermocouples or other heat recording instruments placed on opposite sides of the combustion section. An increase in temperature on one side of the chamber will automatically result in closing the damper on that side a sufficient amount to compensate for the increase and even out the temperature again.

Since many different embodiments of this invention, apparently differing widely, may be made without departing from the spirit thereof, it is to be understood that I do not limit myself to the foregoing description except as indicated in the following claims:

I claim:

1. The method of controlling the position of the center of heat intensity and the direction of fiow of hot gases in the combustion section of a heater, wherein the convection section has means dividing it into a plurality of vertical compartments having fluid heating tubes passing therethrough, said means comprising at least one vertical partition wall extending from the bridge wall in a direction parallel to the general direction of hot gas flow in the combustion section, each compartment being in open communication at its top with the combustion section and otherwise closed except for individual damper means in each compartment, said method comprising controlling the relative quantity of gas passing through each compartment of the convection section by regulating said individual damper means whereby to control the lateral shift of the center of heat concentration Within said combustion section in the direction corresponding to the compartment through which the greater proportion of hot gases are caused to flow.

2. The method of operating a tubular type oil heater having a combustion section separated from a convection section by a bridge wall and provided with oil heating tubes therein, a plurality of vertical partitions within said convection section extending from said bridge wall parallel to the general direction of hot gas flow in the combustion section, thus defining a plurality of chambers in open communication at their tops with the combustion section and otherwise closed except for individual adjustable outlet means;

said method comprising controlling the indi-' vidual outlet means of the respective chambers to cause a larger proportion of the total gas flow to pass through one chamber than through another, thus causing lateral shift of the center of heat intensity in the combustion section to take place in the direction corresponding to the chamber through which the greater portion of the gases are passed, whereby to control the heating effect and the direction of flow of hot gases in the combustion section to provide unchanging heating conditions in the combustion section..

3. In a tubular type heater, means defining an enclosed heater chamber, comprising a floor, a surrounding wall and roof; a bridge wall disposed transversely of the general direction of flow of gases through said heater and extending from said floor to a point below said roof, whereby to divide said chamber into a combustion section and a convection section in communication with each other above said bridge wall, oil heating tubes arranged in banks within said combustion section and said convection section, means for effecting combustion within said combustion section, said convection section being characterized by the provision of at least one vertical partition wall extending from said floor to a point below said roof, said partition wall extending from said bridge wall to said surrounding wall and parallel to the general direction of hot gas flow in the combustion section, whereby to divide said convection section into at least two parallel vertical compartments, said compartments being effective to divide said gas flow from said combustion section into two individual streams parallel to each other along a line transverse to said general direction of hot gas flow in said combustion section, and individual damper means in each of said compartments for controlling the relative quantity of gas flow through each of said compartments, whereby to cause the lateral shifting of the center of heat intensity in said combustion section in the direction of that compartment having the larger quantity of gas flow therethrough.

a. In a tubular type heater,v means defining an enclosed heating chamber comprising a floor, a; surrounding wall, a roof, a bridge wall disposed transversely of the general direction of flow of,

hot gases through said heater and extending from said floor to a point below said roof whereby to divide said chamber into a combustionsection and a convection section in communication with each other above said bridge wall, oil heating tubes arranged in banks within said combustion section and said convection section, said convection section being characterized by the provision of a pluralityof vertical partition walls extending from said'floor to a point below said roof, said: bank of tubesin said convection section being disposed transversely of said general direction of flow of hot gases through said heater, said partition walls extendingfrom said bridge wall to said surrounding wall and having said convection tubes passing therethrough, whereby said convection section is divided into a plurality of substantially coextensive parallel vertical compartments effective to divide said gas flow from said combustion section into a plurality of individual streams parallel to each other along a line transverse to said general direction of hot gas flow in said combustion section, and individual damper means in each of said compartments for controlling the relative proportion of gases fiow' ing through each compartment whereby to cause a lateral shifting of the center of heat intensity in said combustion section in accordance with said relative proportioning of said hot gas flow.

5. In a tubular type heater, means defining an enclosed heating chamber comprising a floor, a surrounding wall, a roof, a bridge wall disposed transversely to the gen ral directionof flow of hot gases through said heater and extending from said floor to a point below said roof, where by" to divide said chamber into a combustion section and a convection section in communica- 7 tion with each' other above said bridge wall, oil

heating tubes arranged in banks within said combustion section and said convection section, said convection :section ,being characterized by the provision of a plurality of partition walls-extending from said floor to a point below said roof; said partition wallsextending from said bridge wall to said surrounding'wall parallel to the general direction of hot gas flow in the comindividual streams parallel to each other along a 7 line transverse to the said general direction of hot gas flow in said combustion section, saidindividual' damper means being eiTective to control the relative proportion of gas flow through each compartment whereby to cause a lateral shift of the center of heat intensity in said combustion section in accordance with said relative proportioning of said hot gas flow.

6. In a tubular type heater, means defining an enclosed heating chamber comprising a floor, a

surrounding wall, roof, a bridge wall disposed transversely of said heater and extending from said floor to a point below said roof, whereby to divide said chamber into a combustion section and a convection section in communication with each other above said bridge wall, means for efiecting combustion within said combustion section, said convection section being characterized by the provision of a plurality of partition walls, said partition walls extending from said floor to a point below said roof and from said bridge wall substantially perpendicular therewith and connecting with said surrounding wall whereby to divide said convection section into a plurality of parallel vertical compartments in open communication at their tops with said combustion section and otherwise closed except for individual damper means in each compartment, said compartments being effective to divide said gas flow from said combustion section into a plurality of individual streams parallel to each other along a line transverse to said general direction of hot gas flow in said combustion section, said individual damper means being operable to control the relative quantity of gases flowing through each

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