Piston-type transfer pump device, method for transferring particulate solid matter using such a device, application of the method to the feeding of a gasification reactor

A piston pump device for transfer between an inlet chamber and an exhaust chamber, the exhaust chamber being pressurized at a greater pressure than pressure in the inlet chamber comprising:

• a tubular sleeve comprising a first inlet orifice in fluid communication with the inlet chamber, and a second exhaust orifice in fluid communication with the exhaust chamber, the inlet orifice and the exhaust orifice being offset longitudinally along the axis of the tubular sleeve, delimiting a third compression chamber between them;
• an inlet piston, sliding in the tubular sleeve between an extreme open position in which it at least partially exposes the inlet orifice in the sleeve and an extreme closed position in which it closes off the inlet orifice while at least partially leaving the exhaust orifice exposed;
• an exhaust piston, sliding in the tubular sleeve between an extreme closed position in which it closes off the exhaust orifice while leaving the inlet orifice exposed, and an extreme open position in which it at least partially exposes the exhaust orifice;
• wherein the inlet piston and the exhaust piston are mechanically independent and are each fitted with sealing rings around their periphery in contact with an internal surface of the sleeve as the pistons slide;
• and
• wherein the exhaust piston and inlet piston are configured to move in a compression phase such that the exhaust piston is held in its extreme position closing the exhaust orifice until the inlet piston reaches a first intermediate closed position in which it closes off the inlet orifice such that the compression chamber is isolated in a fluid tight manner from the inlet chamber and the exhaust chamber, and the exhaust piston jointly with the inlet piston delimits a volume of the compression chamber, the volume of the compression chamber being reduced in the compression phase by the inlet piston moving towards the exhaust piston such that the gas pressure inside it is at least equal to the gas pressure in the exhaust chamber, and then the exhaust piston is configured to slide in an exhaust phase from its extreme closed position to its open position to allow compressed gas to pass into the exhaust chamber.