Feeding apparatus for creation of one or more plugs of compressible material for feeding into a gasifier or reactor
An energy efficient, very flexible and safe feeding apparatus serves for creation of one or more plugs of compressible material for feeding into a gasifier, reactor or other combustion chamber. This apparatus includes a piston feeder with at least three pistons for pre-compressing and delivering compressible material towards a mouthpiece serving as a non-return valve and having an exit end facing a braking device with a friction member for regulating the final degree of compression of the material, and an opposing inlet end for at least partly compressed material. The inner diameter of at least an inlet section extending from the inlet end of the mouthpiece increases towards the first end, so that an angle between the inner wall of at least the inlet section and the longitudinal axis of the mouthpiece is larger than 0° but less than or equal to 3°.
1. A feeding apparatus for creation of one or more plugs of compressible material for feeding into a gasifier or reactor, the apparatus comprising:
a piston feeder comprising at least three pistons configured to pre-compress and convey compressible material;
a mouthpiece serving as a non return valve in communication with the piston feeder and having an inlet end configured to receive at least partly compressed material from the piston feeder, wherein the inner diameter of at least an inlet section extending from an inlet end of said mouthpiece increases towards an exit end, so that an angle between the inner wall of at least the inlet section and the longitudinal axis of the mouthpiece is larger that 0° but less than or equal to 3°;
a braking device situated at the exit end of the mouthpiece with friction means for regulating the final degree of compression of the material;
wherein at least two pistons are configured to pre-compress and convey the compressible material to a third piston and the third piston is configured to convey and further compress the material through the mouthpiece to the braking device to form a plug of compressed material which functions as a safety seal.
2. The feeding apparatus according to claim 1 , wherein the angle between the inner wall of at least the inlet section of the mouthpiece and the longitudinal axis of the mouthpiece is larger than 0° but less than 2°.
3. The feeding apparatus according to claim 1 , wherein the angle between the inner wall of at least the inlet section and the longitudinal axis of the mouthpiece is substantially 0.25°.
4. The feeding apparatus according to claim 1 , wherein the mouthpiece is conical or trumpet-shaped.
5. The feeding apparatus according to claim 1 , wherein the dimensions of the piston feeder, mouthpiece and braking device is configured so that the density of the created plug is sufficient to withhold a pressure difference of up to 50 bar across the length of the plug.
6. The feeding apparatus according to claim 1 , wherein the dimensions of the piston feeder, mouthpiece and braking device is configured so that the density of the created plug is sufficient to withhold a pressure difference of up to 100 bar across the length of the plug.
7. The feeding apparatus according to claim 1 , wherein the piston feeder is configured to keep at least one of the at least three pistons closed during operation.
8. The feeding apparatus according to claim 1 , where the geometry of the apparatus is alterable.
9. A method for creation of at least one plug of compressible material for feeding into a gasifier or reactor, wherein the method comprises the steps of:
providing a feeding apparatus according to claim 1 ,
conveying the compressible material from a container to a last stage of the piston feeder by the use of at least two pistons,
pressing the compressible material towards and through the mouthpiece and braking device by the force of the piston of the last stage of the piston feeder,
compressing the compressible material in the mouthpiece and braking device by the force of the last piston,
forming a plug of compressed material in the mouthpiece, and
pressing the plug from the breaking device to a gasifier, reactor or for further processing.
10. The method according to claim 9 , wherein the length of the created plug is adjusted or varied.
11. The method according to claim 9 , wherein a plug having a length of preferably 3-5 times its diameter is created.
12. The method according to claim 9 , wherein the pistons of the piston feeder are operated so that at all times at least one piston is closed.
13. A method for controlling the formation of at least one plug of compressible material for feeding into a gasifier or reactor comprising the steps of
providing an apparatus according to claim 1 ,
regulating the pressure imposed on the plug by the braking means of the braking device,
regulating the length of the plug by controlling any of the position progression of the final piston in the piston feeder,
measuring the speed and pressure of the last piston during one or more stroke,
regulating the force and motion of the piston strokes on the basis of measurements during the present stroke and during previous strokes, and
signaling to and from a software program collecting, measuring and working up measured data and executing the automation process.