US2223199A - Superheater - Google Patents

Description

Nov. 26, 1940. w. H. ARMACOST. 2,223,199

SUPERHEATER Filed Nov. 25, 1938 J a INVENTOR W/LBUR MAR/macs:

ATTORNEY Patented Nov. 26, 1940 2,223,199 SUPERHEAT'ER} Wilbur H. Armacost, New York, N. Y., assignorto The Superheater Company, New York, 'N..Y. 1

Application November 25, 1938; SerialNo. 242,36 g

'5 Claims. (o1.122- 4so The present invention relates to boilers equipped with superheaters and particularly to improvements in means for bypassing part of the gases around the superheater to regulate the 5 final temperature of the superheated steam It has been found in vertical type water tube boilers having an upper and a lower drum connected by a bank of generating tubes with a superheater located in a down-pass, that a large damper area is required to bypass or 30% of the gases when the bypass damper is located a distance below the steam drum. An object of the present invention is to provide in such'a boiler a damper controlled bypass so arranged and located that the bypass area and thedamper are not of unduly large size. A second object of the invention is to avoid increase in draft loss due to increased resistance to gas fiow through the boiler as a result of the provision of a bypass. 20 Another object is to increase the mass flow of gases over the superheater with consequent greater heat absorption per unit of superheating surface. I

The invention will best be understood upon consideration of the following detailed description and appended claims. when read in conjunction with the accompanying drawing in which the single figure is a diagrammatic elevational view, partly in section, of. a verticaltype water tube boiler embodying the invention.

The boiler illustrated is of the vertical. water tube type and comprises an upper steam drum is disposed above and interconnected with a water drum H by a generating bank l2 consisting of 35 tubes connecting into openings arranged in rows extending longitudinally of the drums with the rows spaced ciroumf erentially of the drums. As shown, the boiler also includesanother upper drum !3 connected to the water drum I I by tubes 4 M and to the steam drum l 0 by tubes [5, IS. The generating bank I 2 includes two baffle-supporting rows of tubes 20 and 2| which are spaced to form a gas pass within which a superheater is located. These tube rows are more closely posi- 45 tioned near the lower drum H soas to restrict or narrow the lower portion .22 of the gas pass, extending to and terminating at its outlet, as compared with the relatively wider upper portion 23 of the gas path extending from the en- 50 trance of the pass to the contiguous restricted portion 22.

On the tube rows 20 the bafiling means 24 extends upwardly from the lower drum II and terminates at a point short of thesteam drum H! 55 while the bafiiing means on the tubes of row 2i extend downwardly from the steamdrum ill and terminate short .of thewater drum H... .As' one means for narrowing thelower portion of U 6 as pass and to form a by-pass, the lower portions 25 of some of the tubes in the row 2| are offset from the row in a direction towards. the tube, row 20 so that the lower portion 22 of ,the gas pass is narrowed or restricted as co pared with its relatively widerupper portion .23., Superheat- I ing elements connectedtoheaders 26 and 21 are 0 so formed and arranged that. a part .2,8flof the superheating elements are located inthe wider portion 23 of the gas pass and apart 29 located in the narrowed portion 22 of the gas pass; The amount of superheatingesurface in the element parts 294s that part which would deter mine the amount. of steam temperature variation. duets, bypassing. The baffling on the. lower offset parts 25 of some tubes in row 2 |1 also.forms-o'ne wall of the bypass around the ,ele'mentsiZS. V The lower 20 parts 30 of other tubes in the row 2|are' offset in the opposite. directio'niso as: tofdefine a. gas. pass 3| alined with therighthand part of the wider portion 23 of the main g'a s pass 'a'nd'substantially parallel tothe narrowed lower portion 220i .the gas pass. .Bafliing meansgii'g aife' provided. on the tubesof the row. Z'lfwith vparts iit and 34 on the tube. portions 23 and. 30, respectively, defining the common wall .of thelower portion 24...of the gas pass and the Icy-pass and 0 the opposite wall of the bypass 3|. v

7 An opening controlled by a damper 35 is provided in the bafiling 33 so that the flow of gases from the wider portion 2510f the gas pass into the bypass 30 may be regulated. It will beappar ent that, if desired, the opening in'thebafliingfit might belocated substantially as shown and the damper 35 itself located at thelower portion of thebypass 3L. I I up In the operation of the above arrangement 40 when the bypass damper 35 is opened to regulate superheat, the portion. of the gases which-are bypassed around the superheater elements 29 in the restricted portion 24 f the bypass flow to and through. the bypass without a change 45 from the direction they follow in flowing through the wider portion 23 of the gas pass andin a direction substantially. parallel to ,theflow of gases through the restricted portions 22 of. the main gas path. Inasmuch as the gases are bypassed without a substantial change in the direction of gas flow no additional resistance is intro duced to the flow of gases through the boiler. such as ordinarily results from turning gases through a bypass leading ofi from" a main pass PATENT Q at an abrupt angle at the point where the entrance to the bypass is located. Furthermore, in boilers having a pass where the gases enter from one side to flow along tubes therein the gases have a tendency to flow across the nearest parts of the superheater and along the inner or further baflle as this is ordinarily the path of least resistance. This fact is of advantage in the arrangement shown since the gases therefore naturally flow toward the bypass and additional draft is not required to induce flow through the bypass. The free cross-sectional area of the narrow portion 22 of the gas path is such that thegas velocities, when the bypass 3| is inuse,

are substantially the same as the gas velocities inthe wider part 23 of the gas pass; This, also, favors the flow of gases through the bypass.

It should also be noted that no appreciable amount of heat is wasted when bypassing to regulate superheat because all of the gases pass over parts of the generating bank after leaving the superheater pass, and bypass.

In addition, when operating the boiler shown withoutbypassing part of the gases, the restricted portion 22 at the lower andouter part of the gas pass has a tendencyto draw the gases back across. the superheater elements from the usual flow path between the inner parts of the superheater and theinner baffie wall. The gases, are also speeded up when flowing through the restricted portion 22 due to the decreased area so that a greater massvfiow over the part 29 of the superheater, and a consequently greater heat absorption results.

While the restricted part 422 v of the gas pass and the bypass .3! might be located near the upper drum .with the widerportion 23 of the gas pass near the lower drum, the arrangement shown in the drawing is. preferred since, for. one thing, thedamper 35 is locatedin a cooler zone because the, bypassed gases have already been partially cooled in passing over the superheating elements 28 in the wider portion of the gas pass before reaching the damper 35. It will also be apparent that other changes and variations may be made without departing'from the-invention as disclosed herein. Accordingly it is desired andintendedto include such variations and changes within the scope of the appended claims.

What I claim is: v

' 1. In a verticaltype water tube boiler having an upper and a lower drum interconnected by a bank of generating, tubes; bafile means forming a gaspass within said bank, having a portion beginning at the entrance to said pass that is wider than a contiguous portion terminating at the exit from said pass,. the flow of gases through said pass being in a direction generally axial of the tubes of said bank; superheater elements located in the relatively .wide portion of saidgas pass and occupying substantially the entire space between said baffle, means; superheater elements.

in the narrow, portion of said gas pass; meansforming a bypass. generallyparallellto the narrow portion of. said gas, pass. and alined with part oftheiwiderportion of said gas pass; and damper means controlling the flow of gases, fromsaid wider portion of said gaspath through said baffle-supporting tube rows spaced to form a pass through which gases flow in a direction generally axial to the tubes in which a superheater may be mounted, parts of said tube rows that are located adjacent one drum being more closely positioned in parallel relation than parts adjacent the other drum to restrict or narrow said pass adjacent said one drum; superheater elements located in the relatively wide portion of said pass and occupying, substantially the entire space between said tube rows; superheater elements in said restricted portion of said gas pass; means forming a by-pass that is alined with and forming a continuation of part of the relatively wide portion of said gas pass and substantially parallel to the restricted portion thereof; and a damper controlling gas flow fromsaid relatively wide portion of said gas pass through said bypass, whereby gases after flowing over the superheater elements in the wider portion of said pass may be. bypassed around the superheater elements in the. restricted portion of said gas path without substantially changing the direction of gas flow.

3. A vertical type water tube boiler having an upper and a lower drum interconnected by a bank of generating tubes that includes two baillesupporting tube rows spaced to form a pass through which gases flow in a direction generally axial of the tubes and in which a superheater may be mounted, some tubes in one of said rows having parts adjacent one drum offset from said row in a direction to restrict or narrow said gas pass adjacent said drum and other tubes in. said row havingparts adjacent said drum offset in the opposite direction and so arranged as to form a bypass alined with part of the relatively wide portion of said gas pass and substantially parallel to the restricted portion of said gas pass; superheater elements located in both the relatively wide and restricted portions of said gas pass;

and a damper controlled outlet from said relatively wide portion of said gas pass to said bypass .whereby gases may be bypassed around the superother of said tube rows to restrict or narrow the lower portion ,of said gas path that lies therebetween as compared with the relatively wider portion of the gas path lying between the upper parts of said tube rows;. superheater elements located in .both' the relatively wide and restricted portions of said gas pass; baflling means on the tubes of said. other row from the lower drum to a point short of the upper. drum; baflling means on the tubes of said one row from said upper drum and along the offset portions of, tubes thereof to a point short. of the lower drum ;.other baille means spaced from the offset bafile supporting parts of tubes in said one rowandacting in conjunction therewith-to form a bypass in alinement with part of, the relatively wider portion ofsaid gas pass and substantially parallel to the narrow portion thereof; and damper means controlling gas flow from said wider portion of said gas pass to said bypass for bypassing part of the gases around the superheater elements in the narrow portion of said gas pass without substantially changing the direction of gas flow.

5. In a vertical type water tube boiler having an upper and a lower drum interconnected by a bank of generating tubes that includes two tube rows spaced to form a downpass through which gases flow in a direction generally axial of the tubes, at least some tubes in one of said rows having their lower portions offset toward the other of said tube rows to restrict or narrow the lower portion of said gas path that lies therebetween as compared with the relatively wider portion of the gas path lying between the upper parts of said tube rows; other tubes in said one row having their lower portions ofiset in a direction away from said other row to define a bypass parallel to the restricted portion of said gas pass and in alinement with part of the relatively wider portion thereof; superheater elements positioned in both the relatively wide and narrow portion of said gas pass; baflling means on the tubes of said other row from the lower drum to a part short of the upper drum; bafliing means on the tubes of said one row from said upper drum and along the ofiset portions of said tubes to points short of the lower drum; and damper means controlling gas flow from said wider portion of said gas pass to said bypass whereby gases may be bypassed around the superheater elements in the restricted portion of said gas path without substantially changing the direction of gas flow.

WILBUR H. ARMACOST.

Images