US2823658A - Combination heat exchange head and combustion chamber - Google Patents

Description

Feb. 18, 1958 e. B. HERBSTER 2,823,658

COMBINATION HEAT EXCHANGE HEAD AND COMBUSTION CHAMBER 2 Sheets-Sheet 1 Filed May 12, ,1954

INVENTOR. 6. W

F 18, 1958" G. B. HERBSTER I 2,823,

COMBINATION HEAT EXCHANGE HEAD AND COMBUSTION CHAMBER 2 Sheets-Sheet 2 Filed May 12, 1954 r r u .1

IN V EN TOR.

nitcd George B. Herbster, Dallas, Tex., assignor to Herbster- Schmiler, lnc., Cleveland, Ohio,.a corporation of Ohio Application May 12, 1954, Serial No. 429,215 9 Claims. Cl. 126-91 This invention relates to 'heating apparatus which is an improvement in the heating apparatus disclosed in United States Letters Patent No. 23314825, issued tome on March-23,'1943.

The present'invention relatesparticularly to the com bination heat exchange head'and combustion chamber of the exchanger disclosed in the above patent and toe means for recuperatingheat from products of combustion discharged from the head;

More specifically, the present inventionrelates to a heat exchanger having a generally'upright heat'exchange head which iscomposedof a plurality of groups of tubes for heating media and whichextend'about a common hOI'ir zontal axis, one group clockwise and one group counterclockwise. The tubes of' each group are spaced apart from each other to provide therebetween, arcuate air passages which extend from frontto rearofthe headand' af ford passages for air through the head in intimate heat exchange relation with the tubes. An integral hollow combustion chamber-is disposed'directly beneath the tubes and is in communication, at its upper end with the lower end of-the tubes. Means are provided for discharging the residua of-the heating media from the tubes at their upper ends. The improvement over the structure disclosed in the above patentresides'in the following: p

Connectors are provided in' the passages betwee'nthe tubes and extend across the passages so as to assure an etlicient how of metal during castingof the combined heat and combustion chamber and to eliminate, chilling and cold spots in the metal in the mold cavity, and thereby making possible the casting of' the entire structure in one piece, and correspondingly to eliminate hot spots and relieve the internal stresses in the metal during the heating and cooling of the head in subsequent use.

The invention is further characterized in that the ribs are arranged on the combustion chamber and cooperate with the connectors for increasing the eifi'ciency ofthe new of metal during casting and' so for equalizing thermal stresses in the structure when the same is in use.

The invention is further characterized in that the addition to the two groups of tubes, a central through tube is provided and is in communication at its lower end with the combustion chamber and at its upper end'with the exhaust outlet of the head and extends vertically across the space between the innermost clockwise extending tube and innermost counterclockwise extending tube.

Another feature of the invention resides in. a fiuebaihje in connection with the heat exchanger. 7

Various objects and advantages ofthe invention willbecome apparent from the following description, wherein reference is made to'the drawings, in-which:

Figures 1, 2 and 3 are a front end elevation, left end elevation, and top plan view, respectively, of av heater embodying the principles of the present invention; and

Figures 4, 5 and 6 are. a ,frontelevation, left side elevation, and topplan view, respectively,.of.the heatexchanger gt the heater illustrated in Figures4 through 6.; parts; of

2 Figures 4 and 5* being shown'in' section for clearness in illustration.

Referring first to Figures 1 through 3, the invention is shown embodied in a heater or furnace which includes an outer casing I having at its top-an openingZfor the discharge of. heated air from the casing, Mounted within the casing' l is an upright heat exchanger indicated generally at 3 including as its upper portion aheat'exchange head land as its lower portion a combustion chamber 5.

The combustion chamberis open at the bottom and is adapted to receive combustible gaseousmedia from the burner 6 and provide-for the combustion thereof without impingement ofv the flame-onthe inner walls of the cham her 5' or head 4. The'chamber 5 is-openat the top so as to admit the heated products from thechamber 5 into the head 4' at the base of the latter. Air'is circulated through the casing and caused to pass in heat exchange relation ship to the entire exchanger 3'by means of a motor driven blowerT; A The head" 4lias at. its upper end an exhaust passage which isconnectedto a suitable flue. 9 which, in turn, leads to the usual stack, not shown. I Referring next to'Figures 4 through 6, the head of the exchanger comprises a plurality of generally upright groups of arcuate tubes, one group extending clockwise and the other group 'counterclockwise about a common horizontal axis, the'tubes extending clockwise being indicated' at 11, 12 and 13;,resp'ectively, and those extending counterclockwise. being indicated. at 1'4, 1'5 and 1'6,'re-' spectively; All of the tubes are connected at their lower ends to the upper end of the combustion chamber'S.

The overall horizontal cross section of the head' 4" is elongated in. a direction generally transversely of the axis about which the tubes extendandis relatively narrow in a direction parallel to the axis. The same is true of the overall horizontal cross section of thechamber 5'.

, The tubes of each group are spaced apart from each other radially of the axis to provide circumferentially extending elongated passages 17 and 18 between the tubes of the'cloekwise group and, 19 and 2'0"between the tubes or the counterclockwise grou p I The passages 18 through 20 extend entirely through the head from front to rear and'provide the air passages for air passing in heat exchange relation'between the tubes. 7

The head 4. has at the top an outlet 21 with which all of, the tubes communicate and which leadslto the flue 9' heretofore described.

, The combined head 4 and combustion chamber 5 comprising the exchanger 3 is a one piece m'etali casting. However, in forming it as a one piece casting, considerable difficulty has been encountered due to cold spots appearing in the metal in the mold cavity during casting, particularly when the structureris made in a sand mold.

' In order to eliminate these cold spots and the unequal chilling ofthe metal and to obtain a better flow of metal into the cavity, connectors. 22 are provided between ad.- jacent tubes and ribs 23 are provided on the walls of the combustion chamber 5,.

As shown in the drawings, the ribs 22 preferably are of solid metal and extend across the passages. between adjacent tubes. They intersect the tube walls. at abrupt angles; The connectors are preferably relatively thinin a direction endwi'se of'the tubes or circumferentially of the head. Forwardly and rearwardly of the medial plane of the head, they extend the major portion. of the dimension, of the head, preferably from the rear face almost to the forward face. They are arranged so that the inner end of, each connector is disposed, endwise of the tubes, close to the outer end of a connector in the: next inwardlyadjacent passage. For instance, referring to the two upper right hand: connectors-.22 in Figure 4, thg

inner end of the uppermost connector 22 in the space 20 is disposed, in a direction endwise of the tube 15, close to the outer end of the upper connector 22 in the space 19. The lower-connectors in each instance are similarly arranged. Each of the connectors 22 is spaced materially from the upper and lower ends of its associated passage between the tubes. The connectors pref erably are fairly uniformly distributedcircumferentially of the head.

It is to be noted that the connectors in the inner pas sages, such as the passages 17 and 19, extend more nearly radially than those in the outer passages 18 and 20. The connectors 22 in the same outer passage are substantially coplanar.

In the form illustrated in Figure 4, the connector in the outer passages, such as 18 and 20, extend at an angle of about 15 to the vertical, respectively. The upper connector in the inner passage 17 extends at about 15 to the vertical in a direction opposite to the upper connector in the outer space 18 and the upper connector in the passage 19 extends at about 15 to the vertical in a direction opposite from the upper connector in the outer space 20. The lower connectors in the spaces 17 and 19 slope downwardly and outwardly from the center of the head, each at an angle of about 40 to the horizontal.

The ribs 23 of the combustion chamber are preferably disposed in approximate alignment vertically with the lower ends of the tubes, respectively, and extend from the bottom of the combustion chamber substantially to the lower ends of the tubes. These ribs are relatively thick forwardly and rearwardly of the head relative to the thickness of the walls thereof. They provide for a ready flow of molten metal into the cavity during casting of the head as a unitary structure.

As to both the connectors 22 and the ribs 23, the same structures appear to increase greatly the radiating surface and the heat exchange from the head to the air passing through the passages while at the same time they reinforce the casting against internal stresses and warpage occasioned by successive periods of heating and cooling during use. They appear to eliminate excessively hot spots created by the products from the burner 6 and render the head temperature more nearly uniform.

In addition to these modifications, a central tube 24 has been provided, the central tube being open at its lower end for receiving products from the combustion chamber and being open at its upper end for communication with the outlet 21. The inlet of the tube 24 is preferably just above the upper level of the inlets of the tubes 11 and 14 and its outlet is preferably just below or at the lower level of the outlets of the tubes 11 and 14. The tube 11 is preferably disposed midway between the tubes 11 and 14 and extends vertically. All of the tubes are relatively narrow in cross section transversely of the axis of the head and relatively long in cross section forwardly and rearwardly of the head.

With the tubes arranged in the manner recited, shortcircuiting of an undue proportion of the products from the combustion chamber through one or more of the tubes and particularly through the tube 24, at the expense of the others, is substantially eliminated, all of the tubes being heated approximately uniformly. By providing the connectors 22, ribs 23 and central tube 24, a much greater B. t. u. output and the heating ofa greater volume of air can be obtained with the exchanger of the present invention relative to that disclosed in the above mentioned patent even when the heads have the same external dimensions.

' Referring to Figure 4, a number of sprue holes are indicated in dotted lines at S. These are the usual sprues from which metal is gated into the mold cavity. As noted, these sprues are arranged generally at the four corners of the cavity which is to form the head with the connectors 22 and ribs 23; An efiicient flow of metal to all parts of the mold cavity is obtained when the exchanger illustrated is cast by metal fed from the four corners concurrently.

In the structure herein described, there are some cases, especially when the head is being taxed to capacity, when an appreciable amount of heat can be recuperated from the part of flue 9 which passes through the casing. Due to the structural arrangement and the manner in which the furnace is to be located in the basement, it usually happens that the flue must extend generally horizontally from the heat exchange head 4 to the stack and that it have between its ends a very abrupt bend, usually It was found that the flue of this nature tended to heat to a considerably higher temperature along the margin the outside of the bend than along the margin at the inside of the bend.

It has been found that by providing a baffle 25 in the flue, the heating effects on the flue of products from the head can be more nearly equalized. When used, the baflle is located so near the flue wall to the inside of the bend and preferably extends from the inlet in the flue continuously to the outlet so as to divide the passage of the flue into two side by side passages, the one to the inner side of the bend being of smaller cross section than the one to the outside of the bend.

In the form shown, for example, the flue is of rectangular cross section and the baflie 25 is parallel to the side walls thereof and extends from the top to the bottom of the passage through the flue. This baflle is arranged about /3 of the width of the flue outwardly from the side wall at the inside of the bend. When so arranged, the heating of the flue approximates much more closely a uniform temperature at all portions across the flue than was theretofore obtained and exceedingly high temperature spots were eliminated.

The carbon dioxide readings taken in the flue indicate that the carbon dioxide is about the same at all portions transversely of the flue when the baflie is utilized whereas it varies materially from one side to the other when the baffle is not used. For example, prior to the introduction of the baflie, the carbon dioxide reading varied from 8 at the wall to the inside of the bend to 10 at the wall to the outside of the bend, whereas with the baffle, an average carbon dioxide reading of about 8.5 is obtained at all points transversely of the flue.

By the combination of the connectors, ribs, central tube 24 and baflle in the flue, a very high degree of efliciency in the exchange of heat from the gaseous heating media to the air is effected, the temperature of the heat exchanger and of the flue is rendered more uniform, the combination head and combustion chamber does not become distorted under repeated heating and cooling, the heat exchange efficiency is increased, and the flow of molten metal into a mold for the combined head and combustion chamber is facilitated so that rejects due to imperfections in casting are reduced to a minimum.

Having thus described my invention, I claim:

1. A heat exchanger and combustion chamber combination comprising a generally upright head having a plurality of groups of substantially arcuate tubes for gaseous heating media, which tubes are concentric to .a horizontal axis and are open at the bottom to receive the heating media and at the top to discharge the heating media, and which extend generally about their common axis whereby the heating media pass through one group clockwise from the bottom to the top of the tubes and through one group counter-clockwise from the bottom to the top of the tubes, the tubes of each group being radially spaced apart from each other to provide therebetween elongated substantially concentric air passages through the head from the front to the rear of the head, said head having walls forming a hollow downwardly opening combustion chamber directly beneath the bottom of the tubes and openings at its upper end into the bottoms of the tubes and adapted to receive at the lower portion secondary air and combustible gaseous fuel from a asaaees the tubes, metal ribs integral with the tubes and positioned with their cross sections, taken in vertical planes extending forwardly and rearwardly of the head, horizontal and said ribs forming connectors across the air passages between adjacent tubes, said connectors being arranged one pair in each arcuate passage of each group, each connector being joined along its longitudinal side margins at an abrupt angle to its associated tubes, respectively, each connector being relatively narrow in cross-section in a direction circumferentially of its associated air passage and spaced a material distance from the circumferential extremities of its associated air passage and extending forwardly and rearwardly through the head the major portion of the forward and rearward extent of its associated air passage, a through tube extending upwardly between the two innermost tubes and arranged to receive at its lower end products from said chamber and to discharge the same at its upper end, said through tube terminating at its lower end at least as high as the upper level of the inlets of the adjacent arcuate tubes and terminating at its upper end substantially at the lower level of the outlets of said adjacent arcuate tubes, all of the aforesaid structure being a onepiece iron casting, and each of said connectors being solid iron.

2. A heating head according to claim 1 characterized in that each connector in each outer passage has its inner side margin disposed, in a position circumferentially of the tubes, close to the outer side margin of a connector in the next inwardly adjacent passage.

3. A heating head according to claim 1 characterized in that the combustion chamber forming walls comprise generally upright front and rear walls, and a plurality of relatively thick ribs are provided exteriorly on, and integral with, said front and rear walls and extend from the lower end of the combustion chamber upwardly near to the level of the lower ends of the tubes.

4. A heating head according to claim 3 characterized in that the ribs are in approximate alignment vertically with the lower ends of their associated tubes, respectively.

5. A heating head according to claim 1 characterized in that a through tube is provided and extends upwardly between the two innermost tubes, and said through tube is arranged to receive products of combustion at its lower end and to discharge the same at its upper end.

6. A heating head according to claim 5 characterized in that all of the tubes are of substantially the same cross section.

7. A heating head according to claim 5 characterized in that said through tube terminates at its lower end at least as high as the upper level of the inlets of the adj-acent arcuate tubes and terminates at its upper end substantially at the lower level of the outlets of said arcuate tubes.

8. A heat exchanger and combustion chamber combination comprising a generally upright head having a plurality of groups of substantially arcuate, tubes for gaseous heating media, which tubes are concentric to a horizontal axis and are open at the bottom to receive the heating media and at the top to discharge the heating media, and which extend generally about their common axis whereby the heating media pass through one group clockwise from the bottom to the top of the tubes and through one group counterclockwise from the bottom to the top of the tubes, the tubes of each group being radially spaced apart from each other to provide therebetween elongated substantially concentric air passages through the head from the front to the rear of the head, said head having walls forming a hollow downwardly opening combustion chamber directly beneath the bottom of the tubes and opening at its upper end into the bottoms of the tubes and adapted to receive at the lower portion secondary air and combustible gaseous fuel from a burner, said head having walls forming an outlet at its upper portion and connected with the tops of the tubes for conducting residua of the gaseous heating media from the tubes, and a through tube extending upwardly between the two innermost tubes and arranged to receive at its lower end products from said chamber and to discharge the same at its upper end, said through tube terminating at its lower end at least as high as the upper level of the inlets of the adjacent arcuate tubes and terminating at its upper end substantially at the lower level of the outlets of said adjacent arcuate tubes.

9. A heat exchanger and combustion chamber combination comprising a generally upright head having a plurality of groups of substantially arcuate tubes for gaseous heating media, which tubes are concentric to a horizontal axis and are open at the bottom to receive the heating media and at the top to discharge the heating media, and which extend generally about their common axis whereby the heating media pass through one group clockwise from the bottom to the top of the tubes and through one group counter-clockwise from the bottom to the top of the tubes, the tubes of each group being radially spaced apart from each other to provide, therebetween elongated substantially concentric air passages through the head from the front to the rear of the head, said head having walls forming a hollow downwardly opening combustion chamber directly beneath the bottom of the tubes and opening at its upper end into the bottoms of the tubes and adapted to receive at the lower portion secondary air and combustible gaseous fuel from a burner, said head having walls forming an outlet at its upper portion and connected with the tops of the tubes for conducting residua of the gaseous heating media from the tubes, metal ribs integral with the tubes and positioned with their cross sections, taken in vertical planes extending forwardly and rearwardly of the head, horizontal and said ribs forming connectors across the air passages between adjacent tubes, each connector being joined along its longitudinal side margins at an abrupt angle to its associated tubes, respectively, each connector being relatively narrow in cross section in a direction circumferentially of its associated air passage and spaced a material distance from the circumferential extremities of its associated air passage and extending forwardly and rearwardly through the head the major portion of the forward and rearward extent of its associated air passage, a through tube extending upwardly between the two innermost tubes and arranged to receive at its lower end products from said chamber and to discharge the same at its upper end, said through tube terminating at its lower end at least as high as the upper level of the inlets of the adjacent arcuate tubes and terminating at its upper end substantially at the lower level of the outlets of said adjacent arcuate tubes, all of the aforesaid structure being a one piece iron casting, and each of said connectors being solid iron.

References Cited in the file of this patent UNITED STATES PATENTS 663,658 Kellogg Dec. 11, 1900 970,483 Fiebeger Sept. 20, 1910 1,595,639 Beard Aug. 10, 1926 1,641,999 Webster Sept. 13, 1927 1,733,158 Kolla Oct. 29, 1929 1,927,002 Olson Sept. 12, 1933 2,159,440 Livar May 23, 1939 2,314,825 Herbster Mar. 23, 1943 2,336,609 Herbster Dec. 14, 1943 FOREIGN PATENTS 20,762 Netherlands Nov. 15, 1929

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