US1757358A - Boiler construction - Google Patents

Description

May 6, 1930. R. DOHERTY BOILER CONSTRUCTION Filed Feb. 24, 1925 I/w/E/v 70/9 Russ/5L1. DOHE/PT) By I Patented May 6, 1930 PATENT errrcs RUSSELL DOHERTY, OF OAK PARK, ILLINOIS BOILER CONSTRUCTION Application filed February 24, 1925. Serial No. 11,223.

The present invention has to do with boiler construction and has for its object the pro vision of improved means for obta1n1ngcomplete combustion in a boiler by providmg unique means for the admisslon of supplemental air thereto.

The invention contemplates the admission of additional air to the firebox or fines in order that the oxygen of the air may combine with the combustion vapors and produce an admixture insuring the complete combustion of the fuel, and the highest heat obtainable. The device is intended to act as a smoke preventive in that enough supplemental air is introduced, and at the proper place, to completely oxidize the carbon of the fuel.

' Among the objects of the invention are the following The provision of a boiler having a plurality of separated throat passages fromthe firebox; i i j An unique arrangement whereby to provide at all times for a free flow of combustion vapors between the firebox and fines;

The provision of a main throat passage and an auxiliary passage for combustion vapors intermediate the firebox and fine, such latter passage having means for admitting supplemental air adjacent or approximate such passage;

The addition to a boiler of an auxiliary throat passage superposed upon the normal throat passage thereof and having means for co-mingling heated air with the combustion vapors during their passage from the firebox to the lines; i

A novel boiler construction providing for two or more throat passages intermediate the firebox and fines, each passage providing means for co-mingling pro-heated air with the combustion vapors.

These, and such other objects as may hereinafter appear, are obtained by the novel construction of the boiler, the combination of the elements therein, and in the arrangement of the parts thereof. For a complete understanding of the invention, reference should be had to the accompanying drawing, illustrative of embodiments of the invention, and in which Figure l is a longitudinal section through the improved boiler.

Figure 2 is a transverse section therethrough on the line 22 of Figure 1, a part of the boiler section structure being broken away to provide a better detail view.

Figure 3 is a fragmentary view, similar to Figure 2, showing a modified type of boiler construction.

Figure 4 is a similar view of another modified form of the invention.

Like reference characters are used to designate similar parts in the drawing and in the specification which follows.

The invention is adapted for use upon furnaces and boilers, but for purposes of illustration a boiler is shown. The boiler illustrated in Figure 1 includes a plurality of ho].- low water containing sections 1, bolted together in the customary way. The usual end sections 2 and 3, are connected to the adjacent sections 1. The front section2 includes various doors and dampers as is usual, and the rear section 3 has a take-off 4. Sections 2 and 3 have conventional water spaces, and all of the water spaces in sections 1, 2, and 3 are in communication as is usual inboiler construction. i

Intermediate two of sections 1 and properly spaced between ends 2 and 3, is a section 5 in which the features of the invention are embodied. The water spaces in section 5 form a part of the communicating water spaces of the boiler, and are designated 5.

By reference to Figure 2, in conjunction with Figure 1, the construction of sections 1 and 5 employed may be readily understood. Flue spaces 6 in said sections 1 and 5 provide for the passage of the combustion gases forwardly through the boiler and a passage 7 in said sections provides for the transfer of such combustion vapors backwardly through the boiler and out through the takeoff 4 to the chimney. A throat passage 8, intermediate the firebox and a bridge wall 9 in a long boiler, or the rear section 3 in a short boiler, allows for the transfer of combustion vapors from the firebox to the fines 6. Said passage 8 may be topped by a transverse air box 10 having a plurality of openings 11 whereby air is admitted downwardly into the passage 8. Box 10 may comprise a separate casting as shown in Figure 2, or be combined in a single casting having two lateral passages as shown in Figure 1. Said box 10 has openings in the sides of section 5, the air admitted through said box being supplemental to that admitted through the various doors and dampers in section 2, and through the grate, designated 8*. Grate 8 preferably extends. from the front of. the boiler tothebridge wall 9, in long boilers and to the rear wall 8 in short boilers.

The transverse air boxor channel 10may.

Y be water cooled as shown in Figure 1 in order to. maintain the temperature of the supplemental air admitted therethrough. below the temperature of the wallsof the air box exposedtothe direct flame, and also to provide protection. for the air box 10 which otherwise would shortly burn outbecause of. the intense heat to which the fire box is exposed.

In. the arch. section 5, immediately above the throat passage 8, is a second or auxiliary throat passage 12. which may be circular as shown in Figure 2, rectangular as. shown in Figure 3,01- of any other preferred shape. Two; circular. throat passages 12 are shown. in. the section illustrated inFigure Any numer i; Openings. 12 may be'usedzto. meet requirements The throat passage 12 is the central aperture through amember or vessel having parallel walls, the external wall 13 of such vessel being abuttedor engaged by the lirehrickorfi-re clay ll builtinto the section '5 about. said apertured.memberand above the air way 10. The internal wall. 15 of said vessel or apertured. member has. aplurality of. ducts 16 opening inwardly. Said open.- ings 1 6, are generallyofi greatest area at. the top of the vessel as. shown or farthest from the air intake, The width of passages 16. decreases as the bottom of the vapertured: member is approached, when the; air box is a h ott m, but w nthe air box is at the top, this, condition is, reversed, Sometimes a. sh ort section. of- Ithe the; wall 15 adjacent the air box is completely closed to prevent ad.- mission of air at thispart of; the throat passage 12, for thereis astrong suction from the combustion gases tending to preventequal distribution of air around, the wholeof throat passage 12 unless. sucha measure asthisisemlayed.

The apertured membenis sox disposed insection that it may readily be connected to or joined to a transverse air passage 17 having damper controls 18 at the external extremities thereof as shown in Figure 2. Such dampers 18 may be actuated by any .of the means common to damper control. In Figure 1 a single casting is shown for forming passages and 17.

Means may also be provided for water cooling the air admitted through the passage 17 as shown. As previously indicated, the purpose of having graduated openings 16 about throat passage 12. is to. insure an even distribution of supplemental air around the throat passage 12 for combination with the combustion vapors passing therethrough. Were the openings 16 all of the same size, more air would be drawn into the aperture from those passages. 16 immediatelyadjacent the air shaft 17 and an unequal distribution of heated air about throat passag 12 would thus. result.

A. single passage could, of course, be utilized to concurrently provide for the admis sion of air into, the throat passages 8 and 12 and this may be done when the sections? are of such dimensionsthat. it is; desirable to do to save space. A. pa ition therebetween is desirable however. The particular position of the passage 17 here disclosed is not the precise position which it must occupy, and, as previously remar hit; may be abov throat passage 12. The configuration of the tlu'oat passage m y, be. v ried. o uit d fte-rent constructions in. boil rs, ls to a commodate itself to fu nace. constructions. By. the structure hi h; i he di cl se the combustion gases formed in thefireboxmay re ets h flue paces by one O -tw ou se hroatpassage r h oat passag 12.- Two;

such throat passages are highly desirable when a; very hot fire is required for these insure suff cient draft and; rapid and complete combustion.

In Figure 41., two. throat passages 12 are shown, each adapted to be supplied by a transverse air box 17. Such a structure is desirable when the charactenof .fuelrequires arge olume of; supplemental air, o the boiler is of such width that it requires several passages.

It is very truethatmost janitors and. caretakers are not familiar. with. the principles underlying, the proper; firing of boilers, and, this lack of knowledge has. often. caused a furnace to be condemned when, as a matter of; fact, t he fault resided wholly in the person firing the boiler. When a fire isbanked high,there is aninadequate opening through throat passage 8 for the combustion vapors to travel. The throat passage 8 is sometimes completely closed. by f-uelpoorly placed, and will permit of the passage of" practically no combustion vapor. This condition maycause violent explosions. It is self apparent that no fireman, however negligent, could obstruct the throat passage or throat passages 12, and a proper draft through the boiler or furnace at all times is thus assured when an auxiliary throat passage such as I have described is employed.

In order to obtain the highest efficiency for a fire, and to produce all of the heat which a fuel can give off there must be sufiicient air for complete combustion of such fuel. Experiment has demonstrated that the average boiler construction provides insufiicient air to completely oxidize the fuel. It is almost invariably true that enough air can not be admitted through the grate 8 for complete oxidation. F or this reason boilers have been designed with the purpose in view of providing supplemental air in the combustion chamber. Because improperly designed and the air duct or ducts was not properly placed, most of these proposed constructions have been failures.

The present invention is for the purpose of admitting to the combustion chamber such supplemental air as is necessary to provide for a complete combustion of all the fire gases, and concurrently to control the distribution of such air, also, to admit such air at a temperature that it will readily combine with the aforementioned combustion vapors. All of these objects are attained by the structure illustrated.

This is accomplished, in part, by providing two throat passages and supplying the uppermost with a source of supplemental air, it being optional whether the lower throat passage has a source of added air. Further, the desired result is obtained by extending the grate 8 to the bridge wall 9, or beyond the arched section 5. The gases reaching throat passage 12 from the forward section ofthe fire box are underfed in oxygen. From passages 16 oxygen is supplied.

Unless the gases are ignited in the presence of the added supply of oxygen, and subse quent to passing through throat passage 12, the effect of the supplemental air may be lpst. The burning fuel upon the grate 8 to the rear of arched section 5 willusually provide the flame or high heat necessary to ignite the gases which have passed through throat passage 12. Even when the fuel back of throat passage 8 is not luminous, the heat therefrom and the reflected heat of bridge wall 9 is ordinarily sufficient to cause ignition of the aircharged combustion vapors.

The device may be modified to accommodate oil burners, and it is quite manifest that the arrangement may be adapted to furnaces and to boilers other than the type illustrated. Means for protecting the air box may be in the form of a water back, fire clay, or fire brick, or fire resisting material.

I claim:

1. In a boiler having a throat passage and throat passages.

2. In a furnace, a firebox, a grate therein, a bridge wall abutting the rear portion of said grate, a water curtain depending from the roof of said firebox and in a position in advance of said bridge wall and forming a narrow transverse throat passage between said grate and the lower portion of said water curtain, said curtain having a second throat passage formed above said narrow transverse throat passage, and means for admitting a volume of supplemental air in a position to combine with the gases passing through said upper throat passage, and separate means for admitting a volume of supplemental air to said narrow transverse throat passage.

3. In a furnace, a firebox, a grate therein, a bridge wall abutting the rear portion of said grate, a water curtain depending from the roof of said firebox and in a position in advance of said bridge wall and forming a narrow transverse throat passage between said grate and the lower portion of said water curtain, said curtain having an additional throat passage therethrough and above said narrow transverse throat passage, and means for admittin a volume of supplemental air in a position to combine with the gases pass ing through said additional throat passage, separate means for admitting a volume of supplemental air to said narrow transverse throat passage, and means for limiting the temperature of the supplemental air admitted to said throat passages.

4. A furnace as defined in claim 2, wherein the air to said throat passages is admitted through parallel intakes in said water curtain whereby the temperature of said air is limited by the temperature of the water in said water curtain.

In a boiler, the combination with a fire box, of a plurality of throat passages arranged side by side and superposed above said fire box, means for admitting a natural draft of air beneath and through said fire box, independent passages communicating with said fire box and said throat passages for conducting supplemental air thereto, and boiler water chambers in the path of said supplemental air passages to preheat the air prior to its introduction within said boiler.

6. In a boiler, the combination with a fire box, of a plurality of throat passages associated with said fire box, means for admitting a natural draft of air beneath and through said fire box, independent passages communicating with said fire box through said throat passages for conducting supplemental air to said fire box, boiler water chambers in the path of said supplemental air passages to prheat the air; prior to its introduction Within said boiler and Valve control means. for

said supplemental air supplyingpassages.

7. Ina boiler having a grate and a bridge .wall, a throat passage below said Wall and extending its Width there being aseri-es' of horizontally mouthed air ducts in said Wall opening into said throat passage, a second throat passage through said wall andof less than its Width, there being a series, of air ducts in said Wall and having their months atan angle one to another and opening into said secondpassage, and. independent air intakes to each seriesof saidair ducts.

RUSSELL DOHERTY.

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