US2808321A - Rotating grate for gas producers - Google Patents

Description

Oct. 1, 1957 G. JUNKERS ROTATING GRATE FOR GAS PRODUCERS Filed June 16, 1955 REGULATOR AUXILLIA RY STEAM SUPPLY PURE OXYGEN O12 OXYGEN .E NRICHED AIR.

MAIN AIR AND STEAM SUPPLY INVENTORQ JUNKdES.

United States Patent 7' ROTATING GRATE FOR GAS PRODUCERS Gerd Junkers, Essen, Germany, assignor, by mesne assignments, to Koppers Company, Inc., Pittsburgh, Pa, a corporation of Delaware Application June 16, 1955, Serial No. 516,015

5 Claims. (Cl. 48-66) This invention relates to improvements in a rotating grate for gas producers and has for its object the provision of an improved grate construction for such a producer, such grate construction facilitating the maintenance of a uniform ash layer above the grate.

As is known, rotating grate gas producers are so constructed and operated that a layer of ash is maintained above the grate to protect the latter from the reaction temperature within the producer shaft, the thickness of said ash layer being controlled by the rotational speed of the grate and the position of one or more strippers arranged adjacent to the grate and adapted to strip the ash from the grate and direct it to an ash pit. The thickness of the ash layer under any particular working conditions may be adjusted by adjustment of the said rotational speed of the grate and/or by adjustment of the said stripper or strippers; it is known to utilize temperature-sensitive mechanisms adjacent to the grate as a means for detecting the thickness of the ash layer and to cause appropriate adjustments to be made to maintain a predetermined ash layer thickness on the grate.

When there are large and frequent changes in the gas demand upon the producer, or when the latter contains a charge of non-uniform particle size and/or water and ash content, an ash layer of irregular depth may easily be formed upon the grate, this leading to non-uniformity in the distribution of the gasification medium throughout the charge and in consequence inefficient gas produc tion. The restoration of a uniform ash layer upon the grate cannot readily be achieved.

These difiiculties in the operation of gas producers arise whatever the gasification medium employed, viz. air, steam or an air/steam mixture, but are particularly apparent when the gasification medium is oxygen or oxygen-enriched air, or a mixture of steam with oxygen or oxygen-enriched air, the difficulties being dependent upon the oxygen content of the gasification medium.

It will be appreciated that so long as there is a uniform layer of ash over the grate, the resistance to flow of the gasification medium through the grate and into the producer shaft will be uniform over the whole area of the grate. However, When the ash layer becomes nonuniform, the resistance to the gasification medium flow through the grate will decrease in those areas in which the ash layer is of the least thickness so that the gasification medium preferentially flows through the grate in the areas of least ash layer thickness, and may, by increasing the rate of reaction in the charge above such areas, cause damage to the grate in these areas through the generation of excessive temperatures.

With the object of minimising this effect of the ash layer thickness upon the gasification medium distribution, it has been proposed to provide the underside of the grate with compartments of sector form to serve as distribution chambers for the gasification medium, gasification medium being supplied to all these chambers at a uniform pressure so that the tendency for the gasification medium to migrate across the underside of the grate to those 2,808,321 Patented Oct. 1, 1957' ICC areas ofthe latter carrying'the least thickness of ash layer is minimized.

In accordance, with the present invention, I provide, in or for a rotating grate gas producer, a grate construction comprising a rotating grate provided on its underside with sector-shaped compartments and a gasification medium supply conduit .beenath said grate and divided into compartments corresponding with the grate compartments and communicating with the latter, said conduit compartments each being provided with means for regulating the flow of gasification medium therethrough.

With such an arrangement, the supply of gasification medium to the areas of the grate associated with the grate compartments can be independently regulated by adjustment of said flow-regulating means and in this way the thickness of ash layer above each of said grate areas may be controlled so that a uniform ash layer may be maintained over the whole area of the grate. The control of the said flow-regulating means may conveniently be effected automatically by means of temperature/sensitive mechanisms associated with the areas of the grate corresponding with the compartments thereunder.

In accordance with a further feature of the invention, auxiliary conduits may communicate with the said conduit compartments above the said flow-regulating means, these auxiliary conduits being adapted for the admission of oxygen, oxygen-enriched air, and/ or steam to the said conduit compartments to provide for finer control of the ash layer thickness upon the grate.

Thus when the ash layer above a particular area of the grate decreases in thickness, steam may be admitted to the appropriate conduit compartment so that the overall oxygen-content of the gasification medium supplied to said area of the grate is reduced, with a consequent reduction in the exothermic reaction rate in the charge above such area of the grate. Conversely, when the ash layer above an area of the grate increases beyond the desired thickness, oxygen or oxygen-enriched air, may be admitted to the appropriate conduit compartment so that oxygen-enriched gasification medium flows through the said area of the grate and counteracts the tendency of the thicker ash layer to slow down the reaction rate in the charge above such area of the grate. By appropriate adjustment of the amounts of steam and oxygen or oxygenenrlched air introduced into the conduit compartments through. the said auxiliary conduits, the reaction rate in the charge may be maintained uniform over the whole cross-section of the producer shaft with the result that a un form ash layer on the grate will be achieved.

Conveniently, the said temperature-sensitive mechamsms may control the admission of oxygen, oxygen-enriched an, and steam to the said auxiliary conduits and hence to the said conduit compartments.

Desirably, the conduit compartments communicate with the compartments beneath the grate through radially extending apertures thereby to enhance the uniformity of distribution of gasification medium Within the grate compartments.

A preferred embodiment of the invention is illustrated in the acompanying drawings in which:

Figure 1 is a vertical cross-section through the lower part of a rotating grate gas producer equipped with a grate construction in accordance with the present invention; I

Figure 2 is a horizontal section on the line IIII of Figure l; and I Figure 3 is a vertical section on the line III-III of Figure 2 Y The gas producer illustrated in the drawings comprises a shaft 1 defined by a double-walled jacket 2 in which hot water is circulated for cooling purposesithe lower end of the jacket 2 being furnished with a dependent sealing ring 3 which dips under the surface of water contained within an annular ash pit 4.

The bottomof the ash pit 4 is constituted by a horizontal annulus 5 upon which is mounted a grate cornprising a lower portion 6 and an upper portion 7, the assembly comprising the ash pit and grate being rotated about its vertical axis by means of a worm-Wheel 8 meshing with a toothed ring 9 carried by the annulus 5.

The annulus 5 of the ash pit is mounted on a dependent crown 10 which runs on rollers 11 arranged in a circle on the producer foundation 12. Ash collecting in the ash pit 4 is discharged over the outer rim thereof, whilst the ash pit is rotating, by means of an ash levelling device (not shown).

Gasification medium (usually a mixture of steam and air) is introduced into the producer via a conduit 13 which passes through the producer foundation 12 and communicates with the interior of the grate. The annulus 5 carries a dependent sleeve 15 which dips under the surface of water contained in a cup 14 surrounding the conduit 13 so that a gas-tight seal is formed between the conduit 13 and the interior of the grate.

The upper and lower portions of the rotating grate are divided into sector-shaped compartments 16, as clearly shown in Figure 2. The walls 17 of the compartments 16 extend downwardly to meet the annulus 5 upon which the grate is mounted. The walls 17 of the said compartments are preferably formed with flanged extensions 29 which are connected to the adjacent Walls 17, for example by screws. The grate is conveniently formed of cast steel and the upper portion 7 of the grate is of conical form and is furnished with openings 27 through which the gasification medium may pass from the compartments 16 into the producer shaft 1.

The upper part of the conduit 13 is also divided into sector-shaped compartments 28 corresponding to the compartments 16 of the grate; the compartments 28 extend upwardly adjacent to the lower edges of the inner margins of the walls 17 of the compartments 16 so that gasification medium flowing up a conduit compartment 28 is directed to the grate compartment 16 which at that instant lies above the compartment 28. The fact that the walls 17 of the compartments 16 move out of registration with the walls of the conduit compartments 28 during rotation of the grate is not detrimental to the gasification medium flow control provided by the grate construction of this invention, since when such lack of registration occurs, the gasification medium flowing up one conduit compartment 28 is divided between two compartments 16 of the grate so that the gasification medium is still directed substantially to the grate area desired.

Each conduit compartment 28 is furnished at its lower end with means for regulating the flow of gasification medium into such compartment from the undivided portion of the conduit 13, these means conveniently comprising, as shown, a throttle valve 18 which is pivoted at 1-9 and operable from the exterior of the conduit by means of a rod 20; by adjustment of the various rods 20, the distribution of the gasification medium amongst the conduit compartments 28 can readily be controlled.

An auxiliary conduit 21 communicates with each con duit compartment 28 above the throttle valve 18 therein; each auxiliary conduit 21 is provided with a steamadmission valve 22, whilst between the valve 22 and the conduit compartment 28 a further conduit 23 is connected to the conduit 21 and is supplied with oxygen or oxygen-enriched air via a valve 24. By means of the valves 22 and 24, the conduit compartments 28 can be selectively supplied with additional steam or oxygen in appropriate quantities for controlling the ash layer thickness above the corresponding area of the grate.

In operation of the producer above described, the flow of gasification medium to different areas of the grate will be controlled by adjustment of the throttle valves 18; where such adjustment is ineffective to maintain uniformity of the ash layer thickness above the grate, steam will be admitted to those conduit compartments 28 which correspond to the various areas of the grate upon which the ash layer has become too thin, whilst oxygen or oxygen-enriched air will be admitted to those conduit compartments 28 corresponding to areas of the grate carrying an excessive thickness of ash layer.

The adjustment of the throttle valves 18 and the valves 22 and 24 of the auxiliary conduits 21 may be effected manually or automatially. Automatic regulation may be achieved by the use of temperature-sensitive mechanisms which may be located on the grate itself (such as shown at 26 in Figure l) or within the shaft 1 just above the grate; the temperature-sensitive mechanisms would of course be associated with appropriate control means (not shown in the drawings) connected to the said throttle valves 18 and valves 22 and 24.

The conduit compartments 28 may have any suitable cross-section, although a sector-shaped cross-section corresponding to the cross-section of the grate compartments 16 is preferred; the upper ends of the conduit compartments 28 preferably terminate in radially extending apertures 30 (see Figure 3), which act as nozzles directing the gasification medium into the appropriate compartments 16 of the grate.

If desired, the compartments 16 of the grate and also the conduit compartments 28, may be further subdivided by appropriate walls to enable the distribution of gasification medium to radially spaced areas of the grate to be controlled.

What I claim is:

1. In a rotating grate gas producer, a gas producer shaft with a rotating grate, sector shaped vertical compartments arranged around the axis of rotation of the grate on the underside thereof and integrally with the grate, a stationary gasification medium supply conduit beneath the compartments of the grade and coaxial therewith, said conduit being subdivided into a coaxial series of stationary vertical compartments corresponding with rotatable compartments of the grate above and communicating at their upper parts with the lower parts of the grate compartments during rotation of the grate, individually adjustable means for individually regulating the flow of gasification medium through the respective compartments of the supply conduit, and means for feeding the main steam and air supply for the producer bed in common to the supply conduit compartments at their lower parts.

2. In a rotating grate gas producer, a gas producer shaft with a rotating grate, sector shaped vertical compartments arranged around the axis of rotation of the grate on the underside thereof and integrally with the grate, a stationary gasification medium supply conduit beneath the compartments of the grate and coaxial therewith, said conduit being subdivided into a coaxial series of stationary vertical compartments to correspond with rotatable compartments of the grate above and communicating at their upper parts with the lower parts of the grate compartments during rotation of the grate, individually adjustable means for individually regulating the flow of gasification medium through the respective compartments of the supply conduit, and auxiliary conduits individually connected to the compartments of the supply conduit for selective admission thereto of auxiliary oxygen, oxygen-enriched air, and steam.

3. In a rotating grate gas producer, a gas producer shaft with a rotating grate, sector shaped vertical compartments arranged around the axis of rotation of the grate on the underside thereof and integrally with the grate, a stationary gasification medium supply conduit beneath the compartments of the grate and coaxial therewith, said conduit being subdivided into a coaxial series of stationary vertical compartments corresponding with rotatable compartments of the grate above and communicating at their upper parts with the lower parts of the grate compartments during rotation of the grate, individually adjustable means for individually regulating the flow of gasification medium through the respective compartments of the supply conduit, auxiliary conduits individually connected to the compartments of the supply conduit for selective admission thereto of auxiliary oxygen, oxygenenriched air, and steam, and temperature-sensitive elements arranged in the producer shaft to detect variations in the ash layer thickness carried by the different areas above the grate, said elements including means also associated With the aforesaid individually adjustable means for the corresponding compartments of the supply conduit to adjust the same automatically.

4. In a rotating grate gas producer, a gas producer shaft with a rotating grate, sector shaped vertical compartments arranged around the axis of rotation of the grate on the underside thereof and integrally with the grate, a station ary gasification medium supply conduit beneath the compartments of the grate and coaxial therewith, said conduit being subdivided into a coaxial series of stationary vertical compartments corresponding with rotatable compartments of the grate above and communicating at their upper parts with the lower parts of the grate compartments during rotation of the grate, individually adjustable means for individually regulating the flow of gasification medium through the respective compartments of the supply conduit, auxiliary conduits individually connected to the compartments of the supply conduit for selective admission thereto of auxiliary oxygen, oxygen-enriched air, and steam, and temperature-sensitive elements arranged in the producer shaft to detect variations in the ash layer thickness carried by the diiferent areas above the grate, said elements including means also associated with the aforesaid individually adjustable means for the corresponding compartments of the supply conduit to adjust the same automatically, and also associated With the individual auxiliary conduits for the corresponding compart ments of the supply conduit to control the admission of air and steam to said supply conduit compartments.

5. Apparatus as claimed in claim 4, and in which the supply conduit compartments terminate at their upper ends in radially extending slits for directing the gasification medium into the rotating compartments in the rotary grate above.

References Cited in the file of this patent UNITED STATES PATENTS 169,947 Bolender Nov. 16, 1875 655,086 Hunter July 31, 1900 1,928,609 Van Ackeren Sept. 26, 1933 2,056,060 Van Ackeren Sept. 29, 1936 2,108,764 Deringer Feb. 15, 1938 2,164,262 Wagner June 27, 1939

Claims (1)

1. IN A ROTATING GRATE GAS PRODUCER, A GAS PRODUCER SHAFT WITH A ROTATING GRATE, SECTOR SHAPED VERTICAL COMPARTMENTS ARRANGED AROUND THE AXIS OF ROTATION OF THE GRATE ON THE UNDERSIDE THEREOF AND INTGRALLY WITH THE GRATE, A STATIONARY GASIFICATION MEDIUM SUPPLY CONDUIT BENEATH THE COMPARTMENTS OF THE GRADE AND COAXIAL THEREWITH, SAID CONDUIT BEING SUBDIVIDED INTO A COAXIAL SERIES OF STATIONARY VERTICAL COMPARTMENT CORRESPONDING WITH ROTATABLE COMPARTMENTS OF THE GRATE ABOVE AND COMMUNICATING AT THEIR UPPER PARTS WITH THE LOWER PARTS OF THE GRATE COMPARTMENTS DURING ROTATION OF THE GRATE, INDIVIDUALLY ADJUSTABLE MEANS FOR INDIVIDUALLY REGULATING THE FLOW OF GASIFICATION MEDIUM THROUGH THE RESPECTIVE COMPARTMENTS OF THE SUPPLY CONDUIT, AND MEANS FOR FEEDING THE MAIN STEAM AND AIR SUPPLY FOR THE PRODUCER BED IN COMMON TO THE SUPPLY CONDUIT COMPARTMENTS AT THEIR LOWER PARTS.

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