US672973A - Mechanical stoker. - Google Patents

Description

N Patented Apr. 30, 1901. w. R. woop. 7

MECHANICAL STOKER.

(Ap alication-flled Oct. 26, 1899.)

(No Iodol.)

THE mums vzrzna n41, PHOTO-L UNITED STATES PATENT OFFICE.

WILFRED ROTHER Y WOOD, OF LONDON, ENGLAND, ASSIGNOR TO THE AMERICAN STOKER COMPANY, OF NEW YORK, N. Y.

MECHANICAL STOKER.

SPECIFICATION forming part of Letters Patent No. 672,973, dated April 30, 1901.

Application filed October 26, 1899. Serial No. 734,842. (No model.)

T ctZZ whom it may concern:

Be it known that I, WILFRED ROTHERY WOOD,engineer, a citizen of the U nited States of America, residing at 18 Walbrook, in the cityof London, England, have invented a certain new and useful Improvement in Mechanical Stokers, of which the following is a specification.

The present invention relates to detail improvements in mechanical stoking apparatus-such, for example, as is described in my prior patent,No. 608,8l9,dated August 9, 1898. In said patent the feed-screw is shown as having a constantly-decreasing taper and pitch from the outerto the inner end, and in stokers made in accordance with said patent it has been customary for the inner side walls of that portion of the coking or fuel chamberin which the screw rotates to leave or break contact with the screw at a plane drawn approximately through the axis thereof. By experiment I have found that the radial or upward feed of the fuel takes place almost entirely on that side of the screw on which the thread rises, such feed being almost tangential, and that on the descending side the fuel at times tends to cake or accumulate and is fed forward without rising substantially, and as the pitch and taper of the screw decrease the fuel experiences a constant-ly increasing difficulty in radial or upward movement, any tendency to which is partially impeded from the bottom by the boss or stem of the screw, and at times so much power is required to drive the screw that it is sufficient to break the same against the caked material.

According to the present invention it is proposed that the coking or fuel chamber of the magazine should only be open to a radial or upward feed from a point approximately on a horizontal plane with the axis of the screw on that side uponwhich the thread rises to a point at or slightly past that which would be formed by a plane vertically drawn through the axis and that the screw itself or the portion thereof within the coking-chamber should be a helix or spiral without a core or stem and having a gradually-decreased carrying capacity.

In order that the invention may be clearly understood, reference is made to the accompanying drawings, which show the present invention applied to a stoker of the class indicated; but it is to be understood that the invention is equally applicable to stokers with varying details of construction.

In said drawings, Figure 1 is a longitudinal sectional elevation of so much of the furnace and connected parts as is necessary to show thepresent invention. Fig. 2 is-a sectional elevation, on a larger scale, on line 1 1; and Fig. 3, a like view on line 2 2. 7

As shown, the first or outer portion of feedscrew A has a constant pitch and carrying capacityand is without taper and is provided with a hollow internally-angled boss or stem B, adapted to engage with a corresponding the coking or fuel chamber F is shown in the form of a helix or spiral, having a constantlydecreasing carrying capacity and without a central boss or stem, the omission of which not only gives a greater fuel-space and the fuel a better chance to rise, but also by doing away with the friction between the fuel and the boss reduces very considerably the power required to drive the screw.

To secure the radial or upward feed of the fuel, the inner side wall G of coking or fuel chamber F, upon which the screw rises, leaves said screw on approximately a plane drawn horizontally through the axis of the screw, while the wall H leaves said screw at a point slightly past that which would be formed by a plane drawn vertically through the screws axis. This construction not only prevents the screw from forming cakes or balls of fuel upon its descending side, but also provides a good bearing-surface for such screw throughout its entire length and prevents any possibility of its rising from its proper position. The partial pocketing or inclosing of the screw, as described, not only prevents it from rising, as just described, but also by supporting the coreless spiral or helix-renders it sufficiently rigid for the purpose intended and also enables the opposite ports or twyers of the fuelchamber to be brought much closer together than is usual, thus insuring the penetration of the draft to the center of the fuel and securing a very perfect cooking and combustion of the same.

What I claim is 1. In a mechanical stoker, the combination with a furnace, of a feed-screw, that portion within the fuel-chamber being in the form of a coreless helix or spiral having a graduallydecreasing carrying capacity and delivering radially with relation to the longitudinal axis of the screw, substantially as described.

2. In a mechanical stoker, the combination with a furnace having a coking or fuel chamher with a delivery radially arranged with respect to the longitudinal axis of the chamber, of a feed-screw, that portion within the fuelchaniber being in the form of a coreless helix or spiral having a gradually-decreasing carrying capacity and delivering the fuel radially into the fuel-chamber, substantially as described.

3. In a mechanical stoker, the combination with a furnace having a coking or fuel chamber with a delivery radially arranged with respect to the longitudinal axis of the chamber, of a feed-screw the outer end of which has a constant pitch and diameter and a boss or stem, and that portion within the fuel-chamher being in the form of a coreless helix or spiral having a gradually-decreasing carrying capacity and delivering the fuel radially into the fuel-chamber, substantially as described.

4. In a mechanical stoker, the combination with a furnace having a coking or fuel chamber, of a horizontally-arranged feed-screw, that portion Within the fuel-chamber being in the form of a coreless helix or spiral having a gradually-decreasing carrying capacity and delivering upward into the fuel-chamber, the inner walls of said fuel-chamber leaving said screw at a point approximately in a horizontal plane with the longitudinal axis of said screw at the side upon which it rises and on the descending side at a point slightly beyond that formed by a vertical plane drawn through said longitudinal axis, substantially as described.

In testimony whereof I have hereunto set my hand in the presence of two subscribing witnesses.

.WILFRED ROTHERY WOOD.

Witnesses:

PHILIP M. JUSTICE, ALLEN PERRY JONES.

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