US2558301A - Stoker retort with cooling means and water and steam feeding means - Google Patents

Description

Patented June 26, 1951 UNITED STATES PATENT OFFICE STOKER RETORT WITH COOLING MEANS AND VIATER AND STEAM FEEDING MEANS 13 Claims. 1

This invention relates to the retort or tuyere for stoker fed coal furnaces, and more particularly to a construction for overcoming in a simple manner many of the inconveniences and dithculties present in the prior art constructions.

Anyone who has had experience in repairing stokers and related structures is familiar with the following common troubles with such devices:

(a) Burned out retorts or tuyres,

(b) Warped coal feed worms,

() Clogged air ports,

(d) Clogged air feed chambers,

(e) Smoke-back through the coal hopper,

(f) Worn flights on coal feed worms due to overheating, and

(g) Difficulty in maintaining a fire in mild weather.

Other troubles also occur, some of which result directly or indirectly from the above-enumerated conditions, and these include burned out motors, pin shearing due to warpage of the coal feed worm, excessive fuel consumption, excessive ash" and coke formation resulting from improper combustion caused by improper air supply, smoking from fire doors, etc.

A principal object of my invention is to provide a retort or tuyre construction which will overcome many or all of the above described difficulties.

Briefly, my invention comprises a retort having a water or steam supply and a thermostatic valve arranged to control the temperature of the retort by wetting down the coal in the lower part of the retort, and further by admitting water or steam into cooling passages within the retort. Once inside these passages, the water or steam is heated to a predetermined pressure and then released to an expansion chamber, from which it is conducted through a series of ports into the combustion chamber.

Another object of my invention is to provide an arrangement as just described.

These and other objects of the invention will be apparent from the following specification taken in conjunction with the accompanying drawing, in which:

Fig. 1 is a sectional view, partly in elevation taken through a retort or tuyre constructed according to the invention,

Fig. 2 is a fragmentary sectional View looking downwardly, and taken just below the horizontal upper wall of the tuyre or retort shown in Fig. 1, and

Fig. 3 is a fragmentary view in section showing a modification.

In the drawing, there is shown a base H) which comprises an air feed casing supplied with air through pipe ll. Inside pipe H is a coal supply tube I2 within which coal is fed from right to left in Fig. 1 by a screw l3 driven by a motor or other driving means (not shown).

Positioned above the base it is the retort assembly denoted generally by the numeral I4, the retort being either of one piece or sectional construction, and being located in the combustion chamber of a furnace (not shown). The retort has a generally circular outer wall l5, an upper wall l6, and a frustoconical central wall I! which defines an upwardly flaring retort it having its bottom opening in communication with the upwardly turned end portion of coal supply tube l2. Walls l5 and l? have near their upper limits paired openings 19 canted at an angle from imaginary radial lines drawn from the center of the retort. The bottom of the structure formed by walls I5, It and I? is open so as to receive air from base 10.

A pipe 20 passes through wall [5 and this pipe receives water or steam from a suitable supply (not shown). If steam is used, it may be obtained from the boiler steam line (not shown). The inner end of pipe 20 is connected to a thermostatic valve shown schematically at 2|, and having two outlets, one of which is connected to a tube 22 opening into the lower part of the retort 18, while the other of which connects to a one-way ball check valve 23 or other type of check valve. A bypass 25 around the open position of the ball permits water or steam to pass around the balhbut the closed position of the ball prevents back pressure from being exerted on valve 2|. The temperature at which valve 2| operates is preferably adjustable, as by nut Zia in the schematic showing in the drawing.

The bypass 24 is connected by tube 24 with a passage 25 which maybe in the form of a coil which is in turn connected through one or more suitable spring-pressed or other check valves 26 to an expansion chamber 27 which may also be in the form of a coil, and which also serves as a manifold. The actuating pressures of valves 26 are preferably adjustable, as by means of adjustment bolts 26a controlling the tension on the springs which urge the balls to closed position. Tubes 28 extend from the chamber 2? into openings 19, these tubes being canted similar to the openings 19, and extending partly into openings As is shown in the drawing, the outlet openings of valve 2! are so arranged that the first opening to be uncovered and connected to inlet is the opening to tube 22, and as the valvecontinues to open, the upper opening leading to check valve 23 is uncovered.

Operation When the temperature of the retort, and hence of valve 2! reaches a predetermined range, the valve 2i begins to open and lets water or steam into tube 22. This Wets down the coal in the lower part of the retort.

Upon further opening of valve 2i, water is admitted to check valve 23 and drives the ball of the check valve to the left in Fig. 1,, thus supplying water to bypass 24 and passages or coils 25. The water striking passages 25 is turned to steam, or if steam is fed through pipe 2@, the steam is superheated and ball check 23 is driven back to its closed position, cutting off further Water supply.

The water or steam in passages 25 is turned to superheated steam, and when a predetermined pressure is reached, the check valve or valves 2e are forced open to admit the steam to expansion chamber 2? where it is distributed into tubes 2% which discharge steam into ports is and create a Venturi action as the steam discharges into the combustion chamber. The Ventur'i action of the steam draws air through openings as into the combustion chamber. The canting of the tubes 28 and ports is creates a turbulent motion in the fire chamber and lessens any back pressure of air Within the retort.

When the water, steam and air have cooled the retort and fire down to a predetermined temperature, valve 2! closes automatically, and opens again only when overheating occurs.

The water or steam fed to the retort thus cools the retort, both by absorbing heat in passages 25 and in the spraying of water or steam on the coal and/or fire. The wetting of the coal by tube 22 provides a water trap for gases which try to pass back through the coal hopper.

The steam jets 28 keep air openings i9 open by blowing away obstructions, and by reason of the prevention of excessive temperatures, welding or fusing of clinkers which might block air holes !9 are prevented.

Since the Venturi action and the maintaining open of all openings it reduces the number of such openings necessary, there is less chance for coal and riddlings (gravel) to work into the air chamber. The controlled temperature retort also permits close fits in sectional retorts, since their expansion can now be controlled.

Warped worms and worn conveyor flights are eliminated by dissipation of excess heat in passages 25 before it reaches the worm E3. The water or steam from tube 22 will also cool the worm and lower retort.

A more constant firebed level results from the fact that the coal wet by tube 22 cannot burn until it has dried somewhat, so that the unburned coal in the bottom of the firebe d will keep the level up. This is particularly important in mild weather when little coal is being fed to the retort. The maintaining of the .flrebed level prevents overheating of the lower retort and the coal feed worm. Overheating of the worm causes it to lose temper and hardness, resulting in more rapid wear from abrasion by the coal. Overheating of the worm might also cause warping, with the attendant difficulties.

A highly important advantage of my construction is the increased 'fuel economy resulting from its use. An explanation follows:

The most active combustion in a stoker fired furnace occurs in the center of the combustion chamber (where the retort is located), since it is there that fresh coal is being supplied and air has its inlet. (In a manually fired furnace, combustion is usually uniform throughout the entire firepot due to the fact that the grates, which allow air to reach the fire, extend beneath the entire area of the firebed.) In the ordinary Stoker fired furnace the fresh coal being supplied receives the maximum amount of air when it is first introduced to the combustion chamber from the center of the retort, and from then on, the air it receives diminishes as it is progressively pushed away from the center of the retort to the sides of the combustion chamber. Fresh coal being supplied from the center of the retort tends to compress and cake to form a column as it is being pushed upward through the firebed. This condition is known as treeing or snaking and it is further aggravated by the fact that the coal on the outside of the column burns because it is easily exposed to air, whereas the coal which forms the'core of the column softens under the heat transmitted, and tends to fuse before it is exposed to air and able to burn. In this way the column is pushed above the retort, where it falls to the side of it. and never receives enough air to allow complete combustion. Any clinker re 'moved from a stolrer fired furnace will contain varying amounts of black carbonous particles. Thes particles are pure coal which was buried beneath or surrounded by ash and could not burn because no air could reach them.

It is a known fact that wet coal will burn more efliciently and with less caking tendencies than dry coal. Wet coal upon being heated tends to blossom or expand due to the moisture within it turning to steam and driving the coal particles apart. In this way each minute particle of coal is exposed to the air and has an opportunity to burn.

From the foregoing it can be seen that the water or moist steam (in case steam is fed to pipe 2i!) from the retort will not only provide positive smoke-back control and maintain firebed level, but will also effect even, eflicient combustion and a loose firebed through which air can easily penetrate.

In this invention the superheated steam which is generated in the heating coil is allowed to escape into the combustion chamber through a Venturi steam-air port which not only prevents the air ports from being clogged but also provides a patthrough the firebed and particularly under the firebed so that air can follow and penetrate the Whole mass instead of being deflected upward around the retort. In this Way uniform combustion will result over the whole firebed instead of being centered around the retort.

These steam-air ports are faced at an angle so that the steam and air issuing from the retort tend to create a turbulent swirl or vortex action in the'combustion chamber, resulting in an in termixing of'gases and consequently more efficient combustion.

It is a chemical fact that when hot coal D1 coke is treated with steam a gas isformed, either producer gas or water gas. These gases are; almost wholly combustible and burn with an intense hot blue flame. It can be seen then that the steam "issuing from the retort andthe steam formed by the heating of the wet m1- will result 5, in a chemical production ofgases that will burn and greatly aid fuel economy.

From the foregoing, it will now be clear that I have provided a construction which obviates many of the difficulties heretofore experienced with stokers, and which provides a greatly increased efficiency.

The construction I have described is only a preferred form of the invention, and is not to be considered as the only form, since various modifications could be made without departing from the inventive concept, as deiined by the appended claims. For example, other suitable types of check means could be used in place of ball check valves 23 and 26. It might also be desirable to use separate control valves for tube 22 and for the supply of water or steam to check Valve 23. Further, there might be several tubes 22 fed by one or more thermostatically controlled Valves, and more than one inlet 2!! could be used. In addition, a one way valve opening only toward valve 2| might be desirable in pipe 23, and, if desired, a spring can be provided to urge ball 23 to the right to its closed position, and the spring tension can be adjustable, if desired. These are just examples of possible variations, and are not to be taken as excluding others.

It should be emphasized again that the drawing is somewhat schematic in its showing, and the invention is not considered limited in its application to the use of coils at 25, since in actual manufacture, a one piece retort could be integrally cast with a series of passages or a hollow jacket instead of the coil and expansion chamber 2?. The individual tuyeres of a sectional retort could be cast with holes which would form a jacket or coil when placed together as a unit. The thermostatic valves, ball check valves, etc. would then be incorporated in one or more master tuyeres.

In the modification of the invention shown in Figure 3, I have shown an arrangement providing extended controls for the check valve between the coil or chamber and chamber 21, and also for the thermostatic valve 2!. In Figure 3, the outside wall of the furnace is represented by broken line H36, and the coils or chambers I25 correspond to chambers 25 in Figure 2. The thermostatic valve is shown diagrammatically at lzl, and the outer wall of the retort is shown at H5.

In order to provide for adjustment of valves lZl and i253 from outside the furnace, the ad-- justment control screw 25a of Figure 2 is extended to a point outside the furnace wall as is shown at IZEia in Figure 3. A similar extension lZl is used on the thermostatic valve IZI.

The valves 26 and El of Figure 2 could be made nonadjustable, and such a construction might be useful for home heating purposes. However, it would be preferable to have adjusting means for the valves 2! and 26, preferably where the installation is for use in industrial applications, where a -fine degree of combustion control is desirable.

The provision of controls Mia and I260, outside of the furnace is desirable, since when a retort is installed in a furnace, it is not unusual for refractory material to be placed around it to form a base or hearth for the fire bed, thus making it difficult to remove and adjust. Such difliculties are completely overcome by the arrangement of Figure 3.

I might point out that in the claims which follow, where I refer to the supplying of water to the thermostatic valve, I also intend to cover P 0 the use of steam, as described'in this specifica tion.

I claim:

1. In a stoker fed coal burning retort, cooling means associated with the retort, means for supplying water to said cooling means, thermostatically operated valve means controlling the supply of water to said cooling means, said valve means being adapted to open with increase in the temperature of the retort and to close with decreasing temperature, means for discharging steam from said cooling means onto the burning coal, and check valve means between said cooling means and said discharging means.

2. In a stoker fed coal burning retort, the arrangement set for-thin claim 1, and a one-way check valve between said thermostatically operated valve and said cooling means.

3. In a stoker fed coal burning retort, the arrangement set forth in claim 1, and means controlled by said thermostatically operated valve means for passing water from said water supply means onto the coal entering said retort.

4. In a stoker fed coal burning retort, the arrangement set forth in claim 1, and means controlled by said thermostatically operated valve means for passing water from said water supply means onto the coal entering said retort, said thermostatically operated valve means being arranged to supply water first to said means for passing water onto the coal entering the retort when the retort becomes heated to a first pre-,

determined temperature, and then to supply water to said cooling means when the retort reaches a second and higher temperature.

5. In a stoker fed coal burning retort, the arrangement set forth in claim 1, said steam discharging means including an expansion chamher, and means for directing steam from said chamber onto the burning coal.

6. In a stoker fed coal burning retort, a retort body having a hollow interior defined by inner and outer Walls, the inner wall forming a central passage to the bottom of which the coal is fed, said inner and outer walls having a plurality of spaced openings in their upper portions, means for feeding air to the interior of said retort body, means forming a cooling passage between said inner and outer walls, means for supplying water to said cooling passage to form steam, an expansion chamber connected to said cooling passage for receiving steam therefrom, and tubes carried by said chamber and extending into said wall openings to discharge steam through said openings onto the burning coal, said tubes extending only partly into said openings to provide a Venturi action.

7. In a stoker fed coal burning retort, a retort body having a hollow interior defined by inner and outer walls, the inner wall forming a central passage to the bottom of which the coal is fed, said inner and outer walls having a plurality of spaced openings in their upperportions, means for feeding air to the interior of said retort body, means forming a cooling passage between said inner and outer walls, means for supplying water to said cooling passage to form steam, an expansion chamber connected to said cooling passage for receiving steam therefrom, and tubes carried by said chamber and extending into said wall openings to discharge steam through said openings onto the burning coal, and a thermostatically controlled valve for controlling the supply of water to said cooling passage, said valve being set to open only when the temperature of the retort" exceeds a predetermined maximum.

8. In a stoker fed coal burning retort, a retort body having :a hollow interior defined by inner and outer walls, the inner wall forming a central passage to the bottom of which the coal is fed, said inner and outer walls having .a plurality of spaced openings in their upper portions, means for feeding air to the interior of said retort body, means forming a cooling passage between said inner and outer walls, means for supplying water to said cooling passage to form steam, an expansion chamber connected to said cooling passage for receiving steam therefrom, and tubes carried by said chamber and extending into said wall openings to discharge steam through said openings onto the burning coal, a thermostatically controlled valve for controlling the supply of water to said cooling passage and means controlled by said thermostatically controlled valve for feeding water from said water supply 7 means onto the coal entering the retort, said valve being adapted to admit water first to said means for feeding water onto the coal entering the retort when the retort becomes heated to a first predetermined temperature and to admit water to said cooling passage when the retort reaches a second and higher predetermined temperature.

9. In a Stoker fed coal burning retort, a retort body having a hollow interior defined by inner and outer walls, the inner wall forming a central passage to the bottom of which the coal is fed, said inner and outer walls having a plurality of spaced openings in their upper portions, means for feeding air to the interior of said retort body, means forming a cooling passage between said inner and outer walls, means for supplying water to said cooling passage to form steam, an expansion chamber connected to said cooling passage for receiving steam therefrom, and tubes carried b said chamber and extending into said wall openings to discharge steam' through said openings onto the burning coal, said tubes and said openings being canted to produce turbulence of the ejected steam.

10. In :a Stoker fed coal burning retort, a retort body having a hollow interior defined by inner and outer walls, the inner wall forming a central passage to the bottom of which the coal is ied, said inner and outer walls having a plurality of spaced openings in their upper portions, means for feeding air to the interior of said retort body, means forming a cooling passage between said inner and outer walls, means for supplying water to said cooling passage to form steam, an expansion chamber connected to said cooling passage for receiving steam therefrom, and tubes carried by said chamber and extending into said wall openings to discharge steam through said openings onto the burning coal, said retort body being generally circular and hollow in the center, said coil and expansion chamber being also generally circular, and said openings and tubes being positioned at angularly spaced intervals.

11. In a stoker fed coal burning retort, the arrangement set forth in claim 1, means for varying the temperature of operation of the thermostatically operated valve means, and means for varying the pressure at which said check valve means operate.

12. In a stoker fed coal burning retort, the arrangem nt set forth in claim 1, means extending outside of the furnace wall for varying the temperature of operation of the thermostatically operated valve means, and means extending outside of the furnace wall for varying the pressure at which said check valve means operate.

13. In a 'stoker fed coal burning retort, cooling means associated with the retort, means for supplying water to said cooling means, thermostatically operated valve means controlling the supply of water to said cooling means, said valve means being adapted to open with increase in the temperature of the retort and to close with decreasing temperatures, and means for discharging steam from said cooling means onto the burning coal.

WARREN E. LA PANTA.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS Number Name Date 101,965 Morris Apr. 12, 1870 1,172,551 Pierce Feb. 22, 1916 1,364,042 Diescher Dec. 28, 1920 2,264,442 James Dec. 2,1941

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