US1717334A - Furnace - Google Patents

Description

Patented June l1, 1929.

UNITED STATESA PATENT OFFICE# LUIS DE FLOREZ, F POMFRET; CONNECTICUT, ASSIGNOR T0 THE TEXAS COMPANY,

lA CORPORATION OF DELAWARE.

- rUaNAcE.

Application led July .2,

to avoid the injurious 'effects of local overjA 1o heating, and several means for obtaining this result have been proposed. So far as I am aware, however, none of the proposed methods result in a complete or substantially complete separation, and'recourse is had to such expedients as. shielding the tubes by a refractory substance or the like in order .to avoid t-he effects ofheat transfer by convection.

In the apparatus'ofmy invention I secure 1926. Serial No. 120,067.

of the flowing current of-the products of combustion. Furthermore, the section 0f the passaget-hrough which the products of combustlon flow is maintained substantially constant which tends to avoid turbulences in flow which might throw the hot gases against the tubes. The gases, having radiated heat to the vertical elements and consequently been reduced in temperature, then pass into the economizer section at such a temperature as vto be substantially nonradiant. The hot gases here come in contact with and flow around a second group of heatabsorbing tubes which are thus consequently adapted ,Ito absorb the convection componentof the leat.

'A feature of the invention is the annular arrangement of heat absorbing tubes Within the combustion chamber permittingI the flama substantially complete -separation of -thm ing gases to pass vertically through the anradiant and convection heat without resort to the interposition of refractory' shields or the like between the source of heat and the tubes, the source of heat and the tubes being v at all times in open communication; The nature of my apparatus furthermore, permits of an arrangement such that sagging of the tubes from lthe effects of heat is avoided, the tubes are readily removable for cleaning and the structure of the furnace is greatly cheapcned and simplified.

' The preferred embodiment of my invention consists of a furnace havin two sections, a combustion chamber of su stantially uniform cross section provided with tubes to absorb the. heatof radiation only, and an economizer section where the products'ofcombustion come into direct contact with a bank of heating elements placed in their ath. I preferably construct my combustion c amb er in cylindrical form, disposing the tubes vertically and supporting them from an upper tube sheet and arranging them so that they virtually line the inner surface of the bustion ass vertically through the center of the comgustion chamber in a direction generally parallel to the plane of the tubes, radiating heat to be vertically disposed tubes but not transferring any substantial amount of heat thereto by contact since the bulk,of the gases will not come in contact with them and the atipsphereimmediately 'surrounding the tubes is substantially out combustion chamber. The products of com-v avoiding the necessity of shielding the tubes as heretofore practiced, such as, for instance, imbedding them in the wall and roof of the combustion chamber, or incasing them in heat resisting material. l

When the vertically disposed tubes arealranged circularly about the source of heat and the path of the heated gases they form a protective'lining or shield for the 'walls of the furnace, which consequently may be of lighter construction, and less heat will be lost by radiation through the walls, as they receive only a portion of the heat imparted to them in existing furnace designs.

y The invention also provides other novel arrangements, such as a simple method of supporting the tubes, whereby they may 'be readil removed .for renewal and accessible from oth ends for cleaning.

"The invention will best be understood if thefollowing description is read in connection with the accompanying drawings, vin which A Figure -1- is' a side elevation partially in section of a furnace according to my inven- Y 'scale of the upper tube'N sheet of the combustion chamber shownin Figure 1;

Figure 3 is a detail-view showing themani n'er of mounting the tubes in the combustion chamber as shown in Figure 1;

Figure 4 is a detail perspective view of the lower casting giving access to the bottom of the tubes of the combustion chamber of Figure 1;

Figure 5 is a central longitudinal section through a modified form of my invention in which the combustion chamber is fired from the top, the products of combustion descending and passing through an underground flue into the economizer section;

Figure 6 is a detail view showing the manner of mounting the U-tubes used in the combustion chamber shown in Figure 5;

Figure 7 is a section on the line 7-7 of Figure 5, showing the manner in which the tube ends are connected; and

Figure 8 is a detail plan view of the upper tube sheet of the combustion chamber shown in Figure 5.

In the embodiment of my invention shown inFigures'l to 4, 10 represents a cylindrical combustion chamber built of brick work or other suitable material which 'may be held in shape merely by the circular bands 11. It will be understood that the combustion chamber may equally well be made somewhat conical or chimney-like in shape, and that this construction may be desirable with a high furnace as an aid to structural stability or for the purpose of modifying the section to allow for the change in volume of the products of combustion to maintain uniformity of low. At the bottornof the combustion cham ber a burner 1 2 or other source of heat is located inside the tire box 13, the sides of which extend well above the burner. At the top of the combustion chamber and extending down into the chamber is aiiue or passageway 14 connecting the combustion chamber. with the economizer section 15, in which is located a bank of tubes 16 preferably positioned horizontally at right angles to the path of the heated gases therethrough. Circularly arranged within the combustion chamber 10 adjacent the side wall but not in contact therewith are the vertically disposed tubes 17 supported from an u per tube sheet 18. The tubes so arranged orm a surface virtually lining the side wall of thefurnace and shielding it from the intense heat to which combustion chamber walls are ordinarily subjected. As shown in Figure 1, the tubes 17 extend well above the lower end of the flue 14 and below the top of the fire box 13. The hot products of combustion flowing up from the burner 12 pass through the center of the furnace, radiating heat to the annularly arranged tubes 17 but not transfertures 19 in the tube sheet 18 and the lower ends project into an annular casting 20 extending around the firebox, which holds the tubes in place and spaces them evenly in relation to one another. The casting 20 serves the function of a lower tube sheet, and is preferably formed in a plurality of arcuate sections open along their outer wall, as shown in Figure 4. Each section may be provided near each end with a strut 21, placed in such position that it will not interfere with the access to the tube headers. The tubes pass through apertures in the upper surface of the cast-ing 20 into the chamber thus provided. The tubes are connected together in series by headers 22 located at their -ends as shown in Figure 3. Ready access may be had to either end of the tubes by means of plugs 23 in the headers 22 for cleaning or otherwise.

As is usual in heating apparatus of this type, the oil or other liquid to be heated Hows first through ythe tubes 16 of the economizer section 15 and then through the tubes 17 of the combustion chamber l0. Preferably the oilin the economizerl section flows countercurrent to the flow of the products of combastion, enteringl the lowest tube 16` of vthe economizer section and fiowing upwardly through the tubes 16 connected in series, the final tube 16 being connected to the upper end of one of the tubes 17 in the combustion chamber 10. The alternate ends of the tubes 17 are connected by headers as shown in Figure and that the upper end of the fire box 13 exy tends above the lower casting 20, forming shoulders behind which gas pockets are formed, thereby tending to prevent the entrance of the fiame into these corners and consequent erosion of the tubes at these points. These shoulders also serve to keepl the flame somewhat centered and away from the tubes during its vertical travel.`

It will be seen that the ends of the tubes and the headers connecting-them are protected from the flame by being housed outside of the heating zone.

In the embodiment of my invention shown in 'Figure 5, which will be described only in so far as it differs from that shown in Figure 1, the'combustion chamber 25 is fired fromthe top by a burner 26. In this modification the connecting flue 27 is located below the combustion chamber 25 and the economizer ring any substantial amount 'of h'eat to the'n 28, and it is possible to support the tubes in tubes by contact since the tubes are situated out of the path of the gases.

The tops of the tubes extend through aperthe combustion chamber in such a manner that when in need of cleaning, a tu' e may be readily removed and a clean tube substituted, thus v to accommodate the ends of the tube 30. The

U-tubes are connected together by return bends 34 which are joined to the tubes by unions 35. In this manner the tubes are held in place only by their own weight and are free to expand or contract as they Vary intemperaturc.

A furnace constructed in accordance with my invention eifectually distributes the work done by the heating surfaces and to a large extent reduces the possibility of overheating of elements' which would be detrimental either to the surfaces thus attacked or to the fluid being heated and flowing within the tubes. As will be seen, this is accomplished by absorbing heat by radiation from the flame until the products of combustion have been so reduced in temperature that they can be safclyput into contact with the usual form of heat-ing elements.

It is, of course, desirable to burnv fuel with the least4 amount of excess air possible, which always results in a high fire box temperature which is detrimental to the walls of the combustion chamber and to the first elements with which the products of combustion come into contact.

By absorbing the radiantiheat from the intense flame caused by burning fuelunder proper conditions, `the temperature of the products of combustion passing out of the combustion chamber is reduced eiliciently by transferring the portion lof the heat that can be withdrawn by radiation and making it perform useful work. The transfer rate on the first contact elements is thus reduced to a safe limit, at the same time permitting efficient combustion of the fuelv without the necessity of admitting excess air.

By disposing the tubes vertically, it will be noted that the section at right angles to the path of the hot gases is substantially uniform, tending to permit a smooth flow and to avoid the forming of eddies around the tubes which would cause a transfer of heat by contact. If the tubes were disposed ging of the tubes, but is an important factor in eliminating heattransfer by contact on the radiant heat elements.

The circular form of the combustion chamber and the shielding of the wall by the heat elements reduces the lcosts of constrction by utilizing a stable form of structure and permitting the use of lighter walls.

The steel work required to hold the combustion chamber together is largely reduced over furnaces of .rectangular sections and the necessity of using arches and roof sections is avoided.

It will be obvious that changes can be made in the design and that the combustion chamber can be built rectangular in cross section without departing from my invention, although the combustion chamber is preferably made circular in form for the above reasons and this circular form is distinctly an improvement on the existing practice. y

In the invention shown by the drawings, one row of tubes has been indicated in the combustion chamber. This, however, is primarily for the purpose of illustration and I contemplate, when necessary, using two or more rows, preferably in staggered relationship, which may be desirable to absorb as much of the radiant heat as possible, and furthermore, the combustion chamber and the economizer sections may be constructed one above the other if desired, although the indicated arrangement is preferred for structural reasons.

Where the term substantially cylindrical combustion chamber is used in the claims,l

it is intended to include a chimney-like construction with somewhat sloping sides.

While two embodimentsof my invention have been described in detail in thevforegoing specification for the purpose of fully disclosing my invention, it is to be understood that my invention is not limited thereto, but includes all changes and modifications whcih fall within ,the scope of the appended claims.

What I claim is:

1'. In afurnace, a vertically arranged substantially c lindrical combustion chamber, a plurality o vertically disposed heat absorbing tubes annularly arranged therein ad]a cent to the walls of the combustion chamber, means for directing burning fluid fuel and the products of combustion thereof in a, central, longitudinal and unobstructed path through said chamber and substantially out 'of contact with said tubes, and means for removably suspending said tubes from their upper ends whereby the lower portions thereof may be capable of lateral movement.

2. In a furnace, a vertical combustion chamber, a burner chamber located at one end of said combustion chamber, an outlet ue located at the other end thereof, said burner chamber and said outlet ueextending into said combustion chamber and having crosssectional areas less than the cross-sectional area of said combustion chamber, and a continuous heating coil arranged in a series of vertically disposed interconnected tubes about said combustion chamber adjacent the Walls thereof and outside the path of the products of combustion, to enable the passage of a continuous Stream of heat absorbing fluid serially through said tubes.

3. In a furnace, a vertical combustion` chamber', a burner chamber located at the upper end thereof, an outlet flue located at the lower end thereof, said burner chamber and said outlet flue extending into said combustidn chamber substantially centrally thereof and having cross-sectional areas less than the cross-sectional area of said combustion chamber, and a continuous heating coil arranged in a series of vertically disposed interconnectedu U-shaped heat absorbing tubes about said combustion chamber adjacent the Wall thereof and outside the path of the products of combustion, to enable the passage of a continuous stream of heat absorbing fluid serially through said tubes.

4. In a furnace, a vertically arranged substantially cylindrical combustion chamber, a continuous heating coil composed of a series of vertically disposed interconnected heat absorbing tubes adjacent to the wall of the combustion chamber and disposed on an annular pitch circle the center of which substantially corresponds With the center of the combustion chamber, and means for` directing burning fuel and the products of combus- .tion thereof in a central longitudinal and unobstructed path through said chamber l`and substantially out of contact with said tubes.

5. In a furnace, a vertically arranged substantially cylindrical combustion chamber,

means for passing products of combustion heated to a radiating temperature centrally and longitudinally thereof in an unobstructed path, and means in said combustion cham'- ber for cooling the products of combustion to a substantially non-radiating temperature comprising a continuous heating coil composed of a series-of interconnected unshielded heat absorbing tubes positioned vertically in the chamber and outside the direct path of the hot products of combustion and arranged in substantially 'uniform spaced relationship to each other and to the chamber Wall, enabling the passage of a continuous stream of heat absorbing fluid serially through said tubes, whereby local overheating of Walls aud tubes is avoided and absorption of heat by radiation is maintained substantially uniform among the tubes.

(i. In a furnace, a substantially cylindrical vertical combustion` chamber, a continuous heating coil composed of a series of vertically disposed interconnected heat absorbing tubes adjacent to the Wall of the combustion chamber and disposed on an vannular pitch circle the center of which substantiallycorresponds with the center of the combustion chamber, a burner located at one end of the chamber, so positioned centrally with respect to said tubes as to impel its iame and the products of combustion in an unobstructed vertical path substantially parallel to and out of direct contact with said tubes, and means for leading away the combustion gases from the opposite end of said chamber.

In testimony whereof, I have signed my name to this specification this 30th day of June, 1926.

LUIS DE FLOREZ.

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