US1718345A - Boiler - Google Patents

Description

June 25, 1929. .1 A. FREIDAY BOILER Filed March 12, 1927 7F Tl WM? INVENTOR Q/AYA. fifif/ /i/r fihATTOR/VEY Patented June 25, 1929.

1,718,345 PATENT OFFICE- UNITED STATES".

JAY A. FREIDAY, OF EAST ORANGE, NEW JERSEY, ASSIGNOR-TO THOMAS E. MURRAY, OF BROOKLYN, NEW YORK. i

BOILER.

Application filed March 12, 1927. Serial No. 174,736.

This invention aims to provide certain improvements applicable especially to high duty boilers. .The accompanying drawing illustrates in a single figure a longitudinal vertical section of a boiler embodying the invention.

The boiler includes the usual overhead banks 1 and 2 of approximately horizontal water tubes with headers 3 and 4 at the lower ends and 5 and 6 at the upper ends connected to the steam drum 7 from which the steam passes through a superheater 8 to the point of consumption. Baffies 9, 10 and 11 direct the gases in the desired course over and between the several tubes. This is a common arrangement and various modifications of that illu'strated may be utilized with this invention. v

It has been the constant effort of designers n to operate such boilers at higher and higher speeds or ratings, so as to get the maximum quantity of steam per hour out of a given installation,iand this has involved extending the stoker or other fuel supply devices. To get the maximum stoker capacities this part of the apparatus has been extended clear across to the back of the furnace or combustion chamber and even beyond the normal line of the back wall. My invention provides a structure which facilitates the use of such 30 an extended stoker. The front wall 12 of the furnace has a feed opening 13 adjacent to which is the hopper 14 for coal and the feed mechanism indicated diagrammatically at 15 from which extends the stoker grate 16 sloping gradually downward to the rear and dumping the ashes and cinders finally into an ash trough ,17. In order that the stoker grate may be made as long as possible from front to back, I have provided a rear furnace wall 18 which is offset considerably beyond the rear wall of the upper structure as marked by the headers 5 and 6. The wall 18 extends vertically to about the topof the combustion chamber where it meets an arch 19, the inner end of which is curved inward as at 20 to provide for a certain amountof expansion and connects with the upper structure. This wall is exposed to very high temperatures from the radiant heat of the burning fuel. I prefer to protect it and at the same time'to utilize the heat to greatest advantage by lining it with a wall of water tubes 20 extend ng vertically up the face of the vertical portion 18 and tubes 21 along the inner face of the portions 19 and '20. These tubes have head ers 22, 23 and 24 in the locations indicated, the latter communicating with the headers 5 so as to provide a direct and easy circulation of steam from the lower tubing to the steam drum; the cross header 25 at the front which rece ves water from the steam drum, having outside connections as usual leading down to the drum 22 at the base of the rear wall. The intermediate drum 23 may be omitted though it probably facilitates circulation.

Such an offset Wall 18 and arch 19 (either with or without the water lining) provides a very simple and convenient structure which permits the making of the stoker of maximum length. When the water tube lining is added we get an even more beneficial result from the increased stoker size, by reason of the effeet of the radiant heat on the water in these tubes. It has previously been proposed to carry the dumping end of the stoker and the ashpit into .a shallow recess at the back of the furnace, practically the whole space for combustion and mixture of the gases being of the a same cross-sectional area as that of the overhead tubing or less.

According to the present invention, how-v ever, the offset rear Wall extends to a considerable height above the rear end of the stoker and practically to the rear ends of the overhead tubes, allowing only space at the top for the inclined arch and expansion bend, and extending downward well below the front wall. Thus we have a comparatively'high combustion chamber of the full width of the overhead bank of the tubes and of greater length than such tubes throughout substantially the full height of the chamber, and of a greater height at the back than at the ,front, so. as to effect thorough combustion and 'uniform admixture of the gasesbefore their passage through the overhead tubes.

The shape illustrated has also an advantage in connection with the ash pit at the base of the rear wall. A certain amount of cold air enters from the ash pit and is carried up in the current of gases. .With the shape illustrated, this cold air'is forced to take roughly the direction indicated by the dotted arrow, so that at the top, and before the hot gases strike the overhead tubing, they are deflected in an approximately horizontal direction and distributed over the cross-section of the column of hot gases. This crosscurrent also effects a mixing of the combustion gases which improves the combustion n the combustion chamber. Where there is no such lateral movement of the cold air, it is apt to go up in a continuous channel. Coal dust firing and other methods of introducing fuel may also be used here with advantage in Various modifications ma be made by those skilled in the art wit out departing from the invention as defined in the following claims.

What I claim is 1. A boiler having approximately horizontal overhead tubing and a furnace with a high rear wall which is offset beyond the rear ends of the overhead tubes, with an arch at the upper end of said rear wall spanning the distance between it and the rear ends ofsaid overhead tubes, said offset rear wall extending upward vertically practically-to the rear ends of the overhead tubes and extending downward well below the level of the front wall and forming a comparatively high combustion chamber of the full width of the overhead bank of tubes, of reater length than said tubes throughout su stantially the full height of the chamber and of greaterdepth at the back than at the front.

2. A boiler having approximately horizontal overhead tubing and a furnace having a comparatively hi h combustion chamber the rear wall of which is vertical and offset beyond the rear ends of the overhead tubes,

with an arch at the upper end of said rear wall spanning the distance between it and the rear ends of said overhead tubes, incombination with a stoker extending from the front to the rear of the furnace, the offset rear wall extending vertically ractically up to the rear ends of the over ead tubes'to form. a comparatively high combustion chamber of the full width of said tubes and ,of greater length throughout substantially the full ases. g 3. A boiler havingapproximately horizontal overhead tubin and a furnace with a high rear wall which is offset be ond the rear ends of the overhead tubes, wit an arch at the upper end of said rear wall spanning the distance between it and the rear ends of said overhead tubes, said offset rear wall extending upward vertically practicall to the rear ends of the overhead tubes an front wall and forming a comparatively high combustion chamber of the full width of the overhead bank of tubes, of eater length than said tubes throughout su tantially the extending downward well below the level of the full height of the chamber and of reater depth at the back than at the front, said rear wall including vertical water tubes exposed to the radiantheat of the burning fuel. I

4. A boiler having approximately horizon- 7 tal overhead tubing and a furnace having a comparatively high combustion chamber the rear wall of which is vertical and offset beyond the rear ends ofrthe overhead tubes, with an arch at the upper end of said rear Wall spanning the distance between it and the rear ends of said overhead tubes, in combination with a wall of vertical water tubes lining said'rear furnace wall and a stoker extending from the front to the rear of the furnace so that said tubes are exposed to the direct radiant heat of the burning fuel, the offset rear wall extending vertically practically up to the rear ends of the overhead tubes to form a comparatively high combustion chamber of the full width of said tubes and of greater length throughout substantially the full height of the chamber so as to effect thorough combustion and uniform admixture of the gases.

5. A boiler having approximately horizontal overhead tubing and a furnace having a comparatively high-combustion chamber the rear wall of which is vertical and offset beyond the rear ends of the overhead tubes, 05

with an arch at the upper end of said rear stantially the full height of the chamber so as to effect thorough combustion and uniform admixture of the gases.

6. A boiler having approximately horizontal overhead tubing and a furnace with a high rear wall which is offset beyond the rear ends of the overhead tubes, with an arch at'the upper end of said rear wall spanning the distance between it and the rear ends of said overhead tubes, said offset rear wallextending upward vertically practically to the rear ends ofthe overhead tubes and extending downward well below the level of the front wall and forming a comparativelv high combustion chamber of the full width of the overhead bank of tubes, of greater lengththan said tubes throughout substantially the full height of the chamber-and of greater depth at the back than at the front, said rear 1 wall and arch including water .tubesextending from the bottom of the wall up to the rear end of the overhead tubes.

7. A boiler having approximately horizontaloverhead tubing and a furnace having j a comparatively high combustion chamber the rear wall of which is vertical and offset beyond therear ends of the overhead tubes,

said rear wallincluding'vertical water tubes and a stoker extending from the front to the rear of the furnace so that said tubes are exposed to the radiant heat of the burningfuel, the offset rear wall extending vertically practically up to the rear ends of the overmy name.

JAY A. FREIDAY.

head tubes to form a comparatively high 10

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