US2990817A - Vertical tube heater - Google Patents

Description

July 4, 1961 .1. w. THROCKMORTON 2,990,817

VERTICAL TUBE HEATER 2 Sheets-Sheet 1 Filed July 22, 1958 INVENTOR. Joy/v 11/ Ema/(warm 1 v 32 Ell July 4, 1961 J w. THRQCKMORTON 2,990,817

VERTICAL TUBE HEATER 2 Sheets-Sheet 2 Fi led July 22. 1958 INVENTOR. JOHN M/ f/wac/woerml Un d S ew Pat O.

2,990,817 VERTICAL TUBE HEATER John W. Throckmorton, New York, N.Y., assignor, by mesne assignments, to Yuba Consolidated Industries, Inc., San Francisco, 'Calif., a corporation of Delaware Filed July 22, 1958, Ser. No. 750,169

3 claims. (Cl. 122-356) This invention relates to new and useful improvements in tubular furnaces and particularly such as have a cylindrical bank of vertical tubes in the primary heater.

My Patent 2,348,099 has shown and described a heater particularly adapted for shop assembly and for relatively small furnaces of from 1,000,000 to 5,000,000 B.t.u. capacity.

My present invention retains certain of the advantages of my previously patented invention, but incorporates several improvements whereby it is adapted for very large size heaters which are normally assembled at the site where they will be employed.

Referring to the drawings:

FIGURE 1 is a partially sectional elevation of a heater embodying my invention.

FIG. 2 is a sectional plan view on the line 2-2 of FIG. 1.

FIG. 2a is a view corresponding to FIG. 2 of a modified arrangement in which the convection section of the heater is circular in cross section.

FIG. 3 is a sectional plan view on the line 3--3 of FIG. 1.

FIGS. 4 and 5 are diagrammatic views showing furnace tubes connected in a single series coil in FIG. 4, and in a double path multiple coil in FIG. 5.

FIG. 6 is a partially sectional elevation on the line 66 of FIG. 1.

FIG. 7 is a partially sectional elevation corresponding to FIG. 6 showing a modified arrangement of the economizer tubes with four tubular elements in each row of the convection section of the heater instead of two tubes shown in each row as in FIGS. 2 and 6.

Referring more specifically to the modification shown in FIGS. 1 to 6, inclusive, a large, preferably cylindrical, furnace shell 15 is mounted on a plurality of structural steel supporting legs 16 having lugs 17 on which the bottom of the shell is supported. The legs 16 extend above the bottom of the furnace shell and are preferably welded thereto and also extend downwardly to the foundation, being of sufiicient length to support the bottom plate 18 at a height adequate to permit men readily to pass under and make any necessary adjustments on the central burner 19 which is mounted on the bottom plate 18.

Within the shell 15 is a refractory lining 20, and at the top of the shell is mounted a frusto conical throat 21 above which extends a smaller chamber forming a boxlike convection section 22, which may be either rectangular in cross section, as shown in FIG. 2, or circular in cross section, as shown in FIG. 2a.

The cylindrical bank is divided into groups of tubes in order to minimize flow resistance and in order to extend certain of the tubes vertically upward into the smaller furnace chamber where they are provided with extended surface elements and constitute the elements of the convection section 22.

It is desirable to make the convection section smaller than the main heater in order to insure that the gases of combustion flow at high speed in contact with the tubes in the convection section. It is not possible to carry all of the tubes into the relatively small convection section unless this section is made as large as the main heater, and internal bafiles are used in a well known manner, as shown for example in Throckmorton & Wallis Patent No. 2,340,287, issued February 1, 1944.

The present arrangement shows a great saving in expense, since it enables a comparatively small size convection chamber to be made long and thereby renders the usual tall stack unnecessary, and the advantage of using large radius return bends is retained.

Two groups of 8 tubes each are disposed on oppos1te sides of the heater, as shown in FIGURE 1, and the tubes of each group are interconnected in pairs by long radius, substantially concentric loop bends to form a nest of hairpin shaped tube units which may be supported at the top by brackets 25. The remainder of the tubes are divided into two opposite groups located between the first two groups and are formed to follow the general contour of the throat, as clearly shown in FIGURE 6. These tubes extend for a long distance vertically upward to the top of the smaller chamber 22 or 22a and within the chamber are provided with extended surface elements and constitute heating elements in the convection zone 27 of the heater. The tubes of one of the last named groups are interconnected over the top to the opposite tubes of the opposite group. These connections are made by relatively long radius return bends 28 and are arranged in rows, as shown in FIGURE 2 and in FIGURE 2a, so that they largely occupy the hollow space within the rectangular furnace section 22 of FIGURE 2 or the cylindrical furnace section 22a of FIGURE 2a.

The shape of the throat 21 is modified to connect the cylindrical furnace shell with the rectangular convection section 22 of the heater.

At the top of the rectangular furnace section 22 is a crown 23, the section 22 being of suflicient size and length to make it unnecessary to mount a stack at the top of the heater.

As shown in FIG. 3, all of the heater tubes 24 are arranged in a cylindrical bank in the main body of the furnace, are equally spaced from one another and from the refractory wall 20.

Attention is directed to the fact that this heater is simple in construction in that practically all of the return bends are of long radius so that large, heavy pipes may be bent into the desired shape without damage to the tubes.

The modification of FIG. 7 differs from that of FIG. 6 primarily in that a larger furnace box section 30 is mounted on the throat 21 and provides sufiicient space for a series of double return loops 31 instead of the single loop formed by the tubes 27. All of the tubes in the furnace section 30 are provided with extended surface elements so that the remaining heat from the furnace gases is largely absorbed by convection before they pass out of the top of the crown 23.

Various modifications may be made without departing from the spirit of this invention, and I desire that only such limitations be imposed as are indicated in the appended claims.

What I claim:

1. A vertical tube heater comprising a large vertical cylindrical furnace which is tall relative to its diameter, having a ceramic wall adapted to withstand high temperatures, a bottom plate, a single circular bank of vertical heat exchange tubes spaced inwardly from the ceramic wall of the furnace and from each other, wall means forming a chamber of smaller size extending upwardly above the furnace cylinder and substantially axial therewith, a frusto-conical wall forming a throat interposed between the furnace chamber below and the smaller chamber above, said tubes being arranged in two groups each composed of a plurality of said tubes disposed on opposite sides of the heater, the tubes of each of said groups being interconnected in pairs by long radius, substantially concentric loop bends to form a nest of hairpin shaped tube units, the remainder of the tubes being divided into two opposite groups located between the first two groups, the tubes of the second group being formed to follow the general contour of the throat of the heater and extending for a comparatively long distance yertically upward to the top of the smaller chamber within which said tubes are provided with extended surface elements and constitute the convection zone of the heater, the tubes of one of the last named groups being interconnected at said top to the opposite tubes of the opposite group by relatively long radius parallel return bends arranged in rows, whereby the hollow space within the smaller chamber is substantially occupied by the tubes.

References Cited in the file of this patent UNITED STATES PATENTS 250,642 Brott Dec. 13, 1881 2,323,498 Thompson July 6, 1943 2,348,099 Throckmorton May 2, 1944 2,655,136 Barnes Oct. 13, 1953 2,672,130 Barnes Mar. 16, 1954

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