US2873702A

US2873702A - Shaking grates especially for burning different kinds of fuel

Info

Publication number: US2873702A
Application number: US465335A
Authority: US
Inventors: Schulte Wilhelm
Original assignee: L&C Steinmueller GmbH
Current assignee: Hitachi Zosen Inova Steinmueller GmbH
Priority date: 1954-10-28
Filing date: 1954-10-28
Publication date: 1959-02-17
Anticipated expiration: 1976-02-17

Description

W. SCHULTE Feb. 17, 1959 SHAKING GRATES ESPECIALLY FORBURNING DIFFERENT KINDS OF FUEL Filed Oct. 28. 1954 FIG. 1.

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7D RHM DRIVE M54116 lrrvenzar: 4 417561! $6901 2 accordance with the movement of the stoker grate.

United States Patent SHAKING GRATES ESPECIALLY FOR BURNING DIFFERENT KINDS OF FUEL Wilhelm Schulte, Gummersbach, Germany, assignor to L. & C. Steinmuller G. m. b. H., Gummersbach, Germany, a firm Application October 28, 1954, Serial No. 465,335

6 Claims. ('Cl. 110-401) The invention relates to a shaking grate for burning different kinds of fuel, and especially for burning selectively separately or simultaneously different kinds of fuel one of which is essentially of particularly poor quality.

It is known fundamentally in the construction of furnaces to burn simultaneously several and different kinds of fuel on one fire grate. this purpose it is necessary in most cases to provide special arrangements; for example, in the case of stoker grate furnaces to feed the fuelon to the grate by rams, a special delivery device in the form. of a ram being coordinated to each feed shaft conducting a different kind of fuel. The rams are operated when required Ain 5, however, the operation of a stoker grate is entirely dif-' ferent to that of a shaking grate, the ordinary method of charging, for example, a stoker grate cannot be directly applied to a furnace equipped with a shaking grate. Nevertheless it must be borne in mind that extremely good combustion on the shaking grate is primarily dependent upon the characteristic nature of its drive. This means, however, that particularattention must be devoted to the feeding of any additional fuels which, if not in the proper proportion, would lead to a reduction in the efficiency of the combustion process on the grate.

The invention consists in that one kind of fuel is fed from a first supply station on to the shaking grate in the ordinary way by the grate hopper of this grate, the feed or moving forward on the grate being determined by the shaking periods the time of which is limited, whereas the fuel to be additionally burned, preferably a fuel of inferior quality, is fed from a second supply station on to the grate by a special delivering device, for example a ram mechanism moving in a delivery channel, the operation of which, in particular the movement of the ram, takes place, depending upon the nature of the additional fuel, either continuously during the whole working period, or only during the shaking periods of the grate or only during the short intervals between the shaking periods of the grate. In the case of combined combustion, that is burning simultaneously, for example pit coal and lignite, a continuous feed of lignite can be advantageous in the case of the ordinary intermittent shaking movement of the grate, or in the case of intermittent simultaneous periods of rest the simultaneous operation of the delivery device for the additional fuel and of the means for producing the shaking movements of the grate.

Should the necessity arise for burning only additional fuel on the shaking grate, it would be preferable for reasons of ignition, to employ a manner of operation wherein the delivery periods of the fuel are arranged between the shaking periods of the grate, and are timed for about the middle of the stationary period, because then the freshly delivered additional fuel, which is'now to be burned alone, rests for a certain time on the grate It is obvious that for before the shaking movement commences, which is advantageous for the ignition and drying of the fuel.

According to the invention both the timing for the operation of the shaking grate and also that for the movement of the delivery device can be controlled by the time switch for the shaking grate.

Fig. 1 is a longitudinal sectional view of the furnace, including the shaking grate embodying the invention;

Fig. 2 is a schematic diagram of the control for the shaking grate and feeder.

Fuel is fed to the shaking grate 1 from a first supply station by an ordinary delivery hopper 2, the distribution or delivery on to the grate being dependent upon the shaking movements. For burning additional fuel a special delivery device 3 is provided which is arranged in the combustion chamber wall 4 above the delivery hopper 2 of the shaking grate 1. This delivery device 3 has a ram 5 the movements of which in a suitable delivery channel are controlled by a known time switch clock, which acts on the ram thru the intermediary of a drive, likewise not shown in the drawing.

Above and below the delivery device 3 air nozzles 6 and 7 are provided in the wall of the combustion chamber to blow air in the direction of the grate and against the fuel falling freely from the special feed device 3 toward the grate 1. The air nozzle 7 blows air against the fuel to restrain the fuel, and especially fine grained particles from rising higher than the level of air nozzle 7.

If the fuel to be delivered does contain a certain percentage of fine' grained or dust-like material, itis possible with the aid of the air fed thru the nozzles 6 to sift or separate this out so that it burns already when heldin suspension by the air and at the same time the feeding of air thru the nozzles 7 can be advantageously adjusted so that the complete combustion of the fine grained or dust-like component of the fuel takes place in the area between the two points of injection of air, or at least below the upper air nozzle 7. v

The time control means comprises a time switchclock '8 which controls two relay contacts." The time control means is operatively connected to a suitable source of power; one of the contacts is connected to the power line of the reciprocating ram means, thereby controlling selectively the movement of said reciprocating ram means; the other contact being in operative relation with the power supply for the shaking grate drive, thereby also selectively controlling the movement of said shaking grate.

The timing of the movements of both the shaking grate and the reciprocating means is controlled by the time switch clock which is set so as to actuate both the shaking grate and the reciprocating means at any desirable predetermined intervals.

Various changes and modifications may be made without departing from the spirit and scope of the present invention and it is intended that such obvious changes and modifications be embraced by the annexed claims.

Having thus described the invention, what is claimed as new and desired to be secured by Letters Patent, is:

1. A method of feeding two different kinds of fuel into a furnace provided with a shaking grate, comprising the steps of delivering a first kind of fuel from a first supply station to said shaking grate, intermittently feeding a second kind of fuel from a second supply station toward a downwardly directed path leading to said shaking grate at predetermined intervals during operation of said shaking grate, blowing a first stream of air against said second kind of fuel during free fall thereof along said path to thereby effect separation of light-weight particles from relatively heavier particles of said second kind of fuel prior to arrival of the latter at said shaking grate, and periodically interrupting the shaking action of db said grate to bring the latter repeatedly into standstill condition, said step of intermittently feeding said second kind of fuel being carried out only during intervals in which said grate is maintained in said standstill condition.

2. A method according to claim 1, including the step of directing a second stream of air over said second kind of fuel from a location spaced from said first stream of air, said first stream of air and said second stream of air becoming effective on substantially opposite sides of said path.

3. A method according to claim 2, further comprising the step of periodically varying the shaking action of said grate from a maximum to a minimum, whereby during periods of maximum shaking both said kinds of fuel are transported along said grate, while during periods of minimum shaking only a gentle stoking of said kinds of fuel without transporting thereof along said grate is effected. I

4. A method according to claim 3, wherein said step of intermittently feeding said second kind of fuel is carried out only during said periods of minimum shaking of said grate.

5. A furnace comprising a shaking grate, first hopper means for feeding a first kind of fuel onto said shaking grate, second hopper means including a delivery channel positioned above and adjacent said first hopper means for feeding a second kind of fuel toward said shaking grate, reciprocable means movable in said delivery channel for feeding said second kind of fuel in predetermined quantity and at predetermined intervals to said shaking grate, first air nozzle means positioned adjacent one end of and above said delivery channel for restraining fine particles of said second kind of fuel from rising above said first air nozzle means, and second air nozzle means positioned adjacent said one end of said delivery channel and therebelow to separate light Weight particles of said second kind of fuel and to allow their combustion between said first air nozzle means and said second air nozzle means, said delivery channel communicating with the second hopper means, whereby upon operation of said first and second air nozzle means only relatively large size fuel particles from said second kind of fuel will be fed to said shaking grate, said shaking grate being positioned adja- 4 cent said first hopper means, said second hopper means being located remote from said shaking grate to permit feeding of said second kind of fuel along a path determined by the free fall of the latter from said delivery channel.

6. A furnace comprising a shaking grate, first hopper means for feeding a first kind of fuel onto said shaking grate, second hopper means including a delivery channel positioned above and adjacent said first hopper means for feeding a second kind of fuel toward said shaking grate, reciprocable means movable in said delivery channel for feeding said second kind of fuel in predetermined quantity and at predetermined intervals to said shaking grate, time control means in operative connection with said shaking grate for operating said reciprocable means at said predetermined intervals, first air nozzle means positioned adjacent one end of and above said delivery channel for restraining fine particles of said second kind of fuel from rising above said first air nozzle means, and secondv air nozzle means positioned adjacent said one end of said delivery channel and therebelow to separate light weight particles of said second kind of fuel and to allow their combustion between said first air nozzle means and said second air nozzle means, said delivery channel communicating with the second hopper means, whereby upon operation of said first and second air nozzle means only relatively large size fuel particles from said second kind of fuel will be fed to said shaking grate, said shaking grate being positioned adjacent said first hopper, means, said second hopper means being located. remote from said shaking grate to permit feeding of said second kind of fuel along a path determined by the free fall of the latter from said delivery channel.

Referencesv Cited in the file of this patent UNITED STATES PATENTS 398,671 Teed Feb. 26, 1889 510,550 Richards Dec. 12, 1893 2,386,336 Mosshart Oct. 9, 1945 2,483,728 Glaeser Oct. 4, 1949 FOREIGN PATENTS 902,540 Germany Jan. 25, 1954