Conveyors: power-driven – Conveyor section – Pusher conveyor and separate load support surface
Patent
1997-08-04
1999-09-28
Bidwell, James R.
Conveyors: power-driven
Conveyor section
Pusher conveyor and separate load support surface
198741, 414156, B65G 2504
Patent
active
059572663
DESCRIPTION:
BRIEF SUMMARY
TECHNICAL AREA
The present invention relates to an apparatus for feeding of solid fuels according to the preamble of patent claim 1.
STATE OF THE ART
There are a number of different apparatuses on the market, such as piston and push rod feeders, for feeding of solid fuels such as wood chips, bark, coal and peat to combustion plants as well as sludge, slurry, sand etc. in different process plants. Push rod feeders are often arranged as a frame placed on the bottom of a rectangular space. The frame obtains a reciprocal movement by means of hydraulic cylinders placed outside the space and attached to rectangular, horizontally arranged plates attached to the frame, which plates move through openings in a wall of the space. Above the space, a silo or the like is often arranged for storage of the fuel, with a passage between the silo and the space so that the space is continually filled with material. In the frame, and transversal to the direction of movement, feeder means are arranged, which means have a substantially wedge like appearance so that material is pushed in front of the wedges when the frame is moved in one direction and that the wedges so to say slide under the material when the frame is moved in the other direction. This design is well suited for feeding heavy and damp solid fuel material such as wood chips and bark.
If the feeder apparatus is placed close to the burner, it has to be assured that no air can enter from the rear into the space. If air is allowed to enter into the space, there is a great risk that the fuel is ignited in the feeding apparatus, which is very dangerous.
Because the above described design with plates at the end of the frame is very difficult to seal off around the passages in the back wall of the space, it has been necessary to enclose the space behind the feeding apparatus, where the hydraulic cylinders are placed, in order to prevent air from entering that way, when it is placed close to the combustion area. The enclosure has in turn led to reduced serviceability as well as reduced access to repairs.
In order to solve the problem with sealing, circular rods were introduced between the frame and the hydraulic cylinders. Sealing between the rods and the back wall is substantially simplified due to the circular rods, because ordinary packing boxes can be used. The need for enclosing the hydraulic cylinders have thereby been omitted.
This design works very well with respect to sealing and for a variety of solid fuels. However, there are problems occurring with build-up of certain materials, such as damp wood chips and bark, against the back wall because the frame has a tendency of bringing some material with it during its return movement, so that the material is packed so much that the frame eventually is prevented from moving, with operation shut down as a consequence. In order to try to remedy this problem, the back wall has been designed with a rounded part so that the material can slide up along the curving and be mixed with the material coming from above. In practice, this has not proved very successful; the material is still packing with operation shutdowns as a consequence.
BRIEF DESCRIPTION OF THE INVENTION
The aim of the invention is to remedy the above mentioned problems. This is accomplished by an apparatus for feeding of solid matter such as wood chips, bark and the like in a space, limited by a substantially plane bottom plate forming a bottom surface, side walls arranged around the bottom surface, forming limiting surfaces, and an opening in said space, the lower edge of said opening being substantially in the same plane as said bottom surface, pusher means, arranged adjacent to said bottom surface, which pusher means extend through the limiting surface opposite said opening, and drive means arranged outside said limiting surfaces and attached to said pusher means in order to obtain a reciprocating movement of said pusher means in a direction towards and from said opening, characterised in that said pusher means are arranged substantially parallel with
REFERENCES:
patent: 3890889 (1975-06-01), Fishburne
patent: 4157761 (1979-06-01), Debor
patent: 5733116 (1998-03-01), Tanno et al.
Bidwell James R.
Saxlund & Company
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