US1041325A - Furnace for steam-boilers. - Google Patents

Description

BIG. MILLS.

FURNAGE FOR STEAM BOILERS. urmouzon FILED Mia. 14; 1910.

1,041,325., Patented Oct. 15,1912.

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FURNACE FOB STEAM BOILERS. APPLICATION FILED An. 14 1910.

Patented 0ct.15,19 12;

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. x/v Vii/V797? E. G. MILLS. FURNQQB FOR STEAM BOILERS. AnPriiiATIoN FILED APB..14, 1910.

Patented Oct. 15, 1912.

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. inarnn u ii FURNACE FOR STEAM-BOILERS.

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To all whom it may concern:

Be it known that I, EDGAR Conis'ron MILLS, consulting mechanical engineer, a subject of the King of the United Kingdom of Great Britain and Ireland, and resident of Manchester, in the county of Lancaster, England, have invented new and useful Improvements in Furnaces for Steam-Boilers, of which the following is a specification.

My invention aims at the recovery of heat usually lost in radiation through the linings of external furnaces for steam boilers and also at promoting secondary combustion; and it consists in the main of a system of cells or pipes formed or embedded in the lining or walls of such furnaces, through which air previously partially heated or not is circulated and finally delivered by suitable orifices into the furnace chamber over the fuel bed. When such air is admitted over the firebed the delivery orifices are preferably inclined in the direction of the draft and are placed in such positions as best to bring the air'into intimate contact with the volatile gases and carbon nionoxid so as to promote their combustion. Some of such orican be placed over or in or behind the bridge or still further in the fine.

My invention is also equally applicable to furnaces whose air supply is obtained either by chimney draft, induced fan draft, by front fan draft or by steam induction jets.

In the case of external boiler furnaces, mechanically fe d or otherwise, having clinker pits I utilize the otherwise waste heat in the clinker by surrounding it with a chamber through which air is passed on its way to the before described cells or pipes. By this means extremes of temperature in the fire-brick cells or pipes are avoided.

In the accompanying drawings Figure I is a longitudinal section of an external furnace constructed in accordance with my invention shown as applied to an ordinary two-flue Lance-shire type of boiler. Fig.

II gives half cross section and half front elevation ofthe same. Fig. III is a part longitudinal section taken through the center of one of the boiler internal fines, 6.

pm the line to m Fig. II. Fig. IV is a cross section of a furnace suitable for a single fined boiler and for boilers of the type de- Specification of Letters Patent.

Application filed April 14, 1910. Serial No. 555308.

Patented. (let. 11

scribed and. illustrated in the Pat 1i #989,270, granted i rpril llth, 1911 to .f Lester and myself, the half-sections bein taken on lines or a: and y g Fig. V. Fig. is a longitudinal section of the 51131163, taken on the line 2 2 Fig. IV. 1 shows de tailed views in plan and elevation. of the bricks in having recesses formed therein.

Similar letters or fi ures of reference in the various figures refer th the san'ie parts.

A is av boiler shell with its front plate (5 and internal lines a a. The brickwork furnace B formed with sides and arched roof, having ashpit b, firebars Z) and firing door b is built externally to and in front of the boiler A. The aslipit may be open for natural daft or closed as shown by the door I) when. a front fan is used. in which case the cleft is regulated by the wing valve Zf admitting air from the underground air duct C by the sidebox c as seen in Fig. H. The wing valve 6' is operated by the lever 1 either by hand or automatically by the firedoor when opened and closed.

D the ordinary blowoil pit, and access to it and the cleaning out door E is ohtaircd by the space 6 resulting from the formation of the ashpit 7), which, as sho a, is terminated by the inclined plate 6. This plate, however, forms no part of my present invention Cells or pipes l? are formed or embedded in the brickwork of the walls and roof of the furnace B. Each of the longitudinal. cells connected by a branch to an outer distributing pipe or trunk g which in turn is connected to a supply duct (l in which mounted a controlling wing valve operated automatically or otherwise.

From each of the cells 1* a suitable number such as three or more outlets f are formed and coincident with each of them an inclined orifice f is provided in the inner brickwork lining. The cells are preferably made in, short lengths and not jointed, the joints f being left slightly ooen to allow of freedom of expansive nimcnuani.

may be made of iron or other Sllli'l'il'llfi inetal of the furnace gases toward the outlet to the flue or lines a. The orifices are placed above the fuel bed as shown.

In some cases it is desirable to deliver air over or even beyond the firebridge and this is shown in Fig. III in which the orilice or orifices f" are shown situated so as to deliver air above and beyond the bridge H.

The air supplied to the cells by the duct G may be impelled by a fan or may be induced by natural or other draft and it may be cold or partially heated before it enters the cells. Thus in the construction shown in Figs. IV and V the air for the cells is drawn through and from the ashpit b by way of the aperture L controlled by the valve Z or from other suitable source, the ashpit b and aperture L taking the function of the duct Gr, Figs. I and II. It is then passed through the space Z surrounding the clinker pit M from which it abstracts heat and thence passes by passages N, which are preferably provided on both sides of the clinker pit M, to the cells F. By this means the air is heated by waste heat before it enters the cells, the object and advantages being otherwise similar to those already described. In this form the box 0 is provided under the ashpit for extracting the ashes by the door 0 and the box 1 for extracting the clinker by the door 1) while the door 3) is closed. By this means the clinker can be ex tracted while the furnace is at work.

The nozzles f are formed as shown in Fig. 1V1. Two bricks is are molded each with a-recesstapered one way as shown or it may be tapered in depth as well, but in any case the outlet is smaller than the inlet 7c. The two bricks are built in with their recesses adjoining so as to form one through tapered passage. The object is to maintain a good outlet velocity and to allow a lower velocity in the cells and passags.

'Iheoperation of the invention is as follows :The total heat ofv both primary and secondary combustion may be divided into radiant heat and conveyable heat. Most of the former and some of the latter is not directly available in the boiler fiues for evaporative purposes, as it is taken up and dissipated by the furnace brickwork 1n the case of ordinary external brick furnaces. In my invention the radiant heat absorbed by the inner layers of the lining is thereby transformed into conveyable heatand is largely transmitted to the air in the cells F and. nozzles F. This air is thenat such temperature as to make it eminently suitable for secondary combustion for which purpose it is used by passing from the nozzles f into the interior of the furnace, a further advantage being that the main body of the brickwork is protected from excessively high temperatures.

In hand fired furnaces the air permitted to enter by the nozzles is controlled by the valve g to suit the excessive variations in, the demand for oxygen for secondary comcooling surfaces, and the intensely hot gases pass with little or no heat loss into the boiler Hues, thereto give up their heat to the water. \Vith such furnaces the diameter of the internal fines of boilers of the Lancashire type may be considerably reduced.

The external furnaces herein described are applicable to any form or type of steam boiler and also for use with or without forced, induced or other method of obtaining draft.

I am aware that air spaces and separate cells in brickwork settings surrounding in-' ternal furnaces have previously been used, also that heated air from them has been passed into the said furnaces for combustion purposes above and into the fire and from and beyond the bridge, and that in external furnaces passages for air have been formed in the brick settings, but

Having now described my invention and in what manner the same is to be performed, I declare that what I claim as new' and desire to secure by Letters Patent. is

In combination a steanrboilerj'a furnace external to said steam-boiler for providing; heat for steam generation in such boiler, 'a casing for said furnace having walls and roof 'inclosing a chamber forming by its lower part a fuel-chamber to hold a firebcd and by its upper part a secondary coinbustion-space for secondary combustion above the fire-bed in said fuel chamber so that both the fuel chamber with the firebed therein and the secondary combustionspace for secondary combustion are wholly free of contact of water-cooled plates and having within the walls and roof a plurality of air-cells each extending in the direction of and for the greater part of the length of the furnace from front to back and spaced from one another and with a plurality of orifices for each air-cell exair-cells whereby air will pass to said aircells and being heated therein by absarption presence of two witnessegthis sixth day of of he l p s thence -hmn'g-h said 0ri- April 1910.

fices into the secondar cQmblistioms ace 1 for secondary colnhu si m above, the %18. EPGAR GONISION MILLD' 5 bed in the fuel-(gha m fir in Said chamber. Witnesses:

In testimony, that I claim the foregoing HOWARD GHEETHAM, m my invention, I have signed my name in RUTH MAGDALENE vVILsoN.

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