Abstract: A piston member that includes a piston rod provided with a piston serves for reciprocating inside a cylinder barrel, the piston dividing the cylinder barrel chamber into a proximal cylinder barrel chamber having a proximal capped end opposite the piston and a distal cylinder barrel chamber having a distal cylinder barrel end opposite the piston. The piston member has at least one sealing ring or seat arranged inside the distal cylinder barrel chamber at the distal cylinder barrel end. Preferably three consecutive piston members are arranged to operate in a series in an apparatus for transporting coal powder to a gasifier. The movement of the pistons inside the cylinder barrels is controlled in relation to each other to transport apportioned batches of coal powder to a high pressure reactor.

Abstract: 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°.