US2118104A - Combustion device - Google Patents

Description

May 24, 193s. w, W- PECK 2,118,104

COMBUSTION DEVICE Filed Aug. 26, 1935 Patented May 24, 1938 UNITED STATES PATENT OFFICE 2 Claims.

'I'his invention relates to imp-rovements in combustion devices and more particularly to retorts such as used in furnaces, or boilers, equipped with automatic solid fuel stokers.

One of the diiculties encountered in the burning of pulverized solid fuel, such as coal, in retorts placed in the fire boxes of furnaces and boilers, wherein both fuel and air are automatically conducted to the retort is the building up of a mushroom formation of coke at the top of the fuel bed which reduces the efficiency of the apparatus as a combustion device. These socalled coke mushrooms appear as the result of incomplete combustion of the coal due to an insufciency of air supplied to a part of the body of coal in the retort and therefore they generally appear at the central portion of the coal bed which is farthest away from the tuyre openings.

It is therefore an object of my invention to provide an improved retort for solid f'uel stokers wherein the formation of coke mushrooms on the burning fuel bed is eliminated.

Another object is to provide an improved retort that is so shaped as to cause the distribution of air admitted thereto into direct contact with the entire body of coal contained in the retort.

A further object is to provide an improved retort as described wherein rupture or breakage of the perforated tuyre Wall of the retort through thermal expansion is reduced to a minimum.

A further object is to provide a retort, as described, which is so shaped as to distribute the live coal bed over a relatively large area within the fire box of the furnace, or boiler, without materially increasing the fuel capacity of the retort.

Other objects, the advantages and uses of the invention will become apparent after reading the following specification and claims, and after con- Isideration of the drawing forming a part of the specification, wherein:

Fig. 1 is a diagrammatic side elevation of an automatic coal stoker equipped with my improved retort;

Fig. 2 is a top plan view partially in section illustrating the retort in Fig. 1, and

Fig. 3 is a sectional View along the line III- III of Fig. 2.

I have selected for illustration herein three species of my improved retort.

With reference to Figs. 1 to 3, the retort is intended for use with any type of solid fuel stoker such as a pulverized coal stoker illustrated in outline in Fig. 1. Such a stoker may comprise a hopper 2, mechanism, contained within a housing 3, for driving a coal feed screw, indicated in dotted line at 4, by means of which coal from the hopper 2 is conveyed into the bowl or tuyre ring of the retort through an interconnecting tube 5.

My improved retort as illustrated in Figs. l to 3 inclusive, comprises two parts; a tuyre ring I and a wind box 3, both of which may be constructed of cast iron. The wind box 8 has formed in conjunction therewith a tubular portion 9, adapted to form a continuation of the coal feed tube 5, and containing the coal feed screw 4. The innermost end of the portion 9 communicates with the bottom'of the retort. At one side of the tubular passage 9 is a duct Il through which air may be admitted from a blower, forming a conventional part of the stoker mechanism in the 4housing 3, into that portion I4 of the wind box surrounding the bottom wall I0 of the retort and the perforated side wall I2 of the tuyre ring. It is intended in this form of the retort that the wind box 8 shall rest directly upon some supporting surface, as indicated at I3, and therefore such support forms the bottom wall for the air chamber I4 surrounding the retort wall at the inner end of the air duct II.

A clean-out passage I6 is provided on the opposite side of the fuel inlet tube 9 which also communicates with the air chamber I4 and is normally closed by a cap I'I. This passage is employed for the purpose of removing powdered coal from the air chamber, from time to time.

The tuyre ring 1 may be fixed in place upon upstanding wall extensions I8 of the wind box 8, by means of bolts I9, so that it is not necessary to remove the retort from the furnace to replace or repair the tuyre ring; but instead the ring may be detached from the wind box and lifted upwardly and through the re door 22 of the furnace, thus saving the removal and replacement of masonry such as required properly to seal the retort in the furnace.

It will be noted that the contour of the retort, as defined by its inner side wall I2, is substantially heart-shaped" with the narrow end in register with the terminus of the fuel inlet tube 9. This contour provides a cleavage surface 23 which serves to divide the incoming stream of pulverized coal into two parts forming areas indicated at 24 and 25, respectively. The dividing of the coal stream in this manner serves a twofold purpose: i

(A) There is a mechanical disturbance of the Y tuyre wall I2 may be of relatively thin construccoal bed at the cleavage surface 23, which is substantially at the middle point of the aggregate bed area, that functions to break up any coke formation which may have started to form.

(B) The greatest distance between the midportion of the coal bed and the adjacent slotted tuyre wall is reduced, thus to assure complete penetration of the bed of coals by the incoming air admitted through the tuyre slots 28 in the wall I2. This condition likewise discourages the formation of coke mushrooms because it encourages complete combustion, both under natural and forced draft.

As heretofore stated, both tuyre ring 'I and wind box 8 maybe formed of cast iron, preferably gray iron, and that wall of the wind box forming the bottom wall I0 of the retort and tion, thus expediting heat radiation which, iS highly desirable in keeping the Wall cool to prolong the useful life of the retort.

Another and important feature of my improved retort is the contour and arrangement of the plurality of tuyre slots 28 formed through the tuyre wall I2. vertically spaced groups throughout the entire wall surface, the slots of one group being staggered with respect to the slots of the adjacent groups. This arrangement greatly increases the limit of elasticity of the tuyre wall under thermal expansion beyond which rupture or breakage of the wall may take place. Under actual working conditions I have observed local bulging of the tuyre wall, under Vthermal ex-v pansion, to an extent which would have resulted in rupture or breakage were it not for this staggering of the slots and consequent staggering of the portions between the slots. Another feature of the'retort is the formation of the tuyre slots with their side walls 3I diverging in the direction of the air chamber. This simple yet highly effective arrangement precludes the choking of the tuyre slots by fuel or ash which may pass These slots are arranged inV into the slots from within the retort. Such material having once entered the slot must necessarily fall into the air chamber I4 where it may be removed at leisure through the clean-out passageway I 6.

I claim as my invention:

1. A combustion device comprising a cast ferrous` metal retort comprising an enclosing wall sloping downward and inward, said reto-rt being approximately heart-shaped in horizontal contour and having an opening adjacent the bottom thereof at the narrow end thereof for admitting pulverized coal, whereby coal admitted toV said heart-shaped retort will be divided into two angularly divergent streams, and means providing an air chamber surrounding the retort and having an air inlet through which air under pressure may be admitted to the chamber, the wall of said retort being further formed with a plurality of elongated tuyre slots therethrough arranged in vertically spaced groups, the slotsy of one group being staggered relative to the slots of the adjacent group.

2. A combustion device comprising a cast ferrous metal retort approximately heart-shaped in horizontal cross section, said retort comprising an enclosing wall sloping downward and inward, with the wall at the central portion of the Vretort sloping downward toward the narrow end of the retort to provide a dividing ridge at a point beyond the mid-section of the retort, whereby to induce divergence and elevation of pulverized coal` admitted to the retort through the narrow end thereof, means providing an entrance for pulverized fuel at the narrow end of the retort adjacent the bottom thereof and in Valignment with said dividing ridge, and means providing an air chamber surrounding the retort and having an aii` inlet opening through which air under pressure may be admitted, the wall of the retort being provided with a plurality of tuyre slots therethrough. Y

WILLIAM W. PECK.

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