Feeding system and method for feeding comminuted cellulosic material to a high-pressure treatment zone

A system for feeding comminuted cellulosic material from a low-pressure zone to a high-pressure zone with at least 1 bar higher pressure, comprising:

• An inlet chamber connected to the flow of comminuted cellulosic material from a low-pressure zone;
• a feeding pipe for feeding the comminuted cellulosic material from the inlet chamber to the high-pressure zone, with an inlet end of said feeding pipe connected to the inlet chamber in the low-pressure zone and an outlet end of said feeding pipe in the high-pressure zone;
• a feeding screw arranged in the feeding pipe, driven by a motor such that the comminuted cellulosic material is transported from the inlet end towards the outlet end of the feeding pipe;
• a restriction member in the feeding pipe reducing the flow section of the feeding pipe closer to the outlet end of the feeding pipe;
• characterized in that the wall of the feeding pipe in an intermediate position between the inlet end and the outlet end is equipped with a pressure relief outlet connected to a pressure relief atmosphere with a pressure lower then 0.5 bars lower than the pressure in the high-pressure zone, this pressure relief atmosphere evacuating any back blow pulses from the high-pressure zone from the flow of comminuted material transported in said feeding pipe before reaching the low-pressure zone and, wherein the pressure relief outlet has a screen member at the entry of the pressure relief outlet, i.e. in level with the wall of the feeding pipe, preventing expansion of the plug of comminuted material into the pressure relief outlet.

A method for feeding comminuted cellulosic material from a low-pressure zone to a high-pressure zone with at least 1 bar higher pressure, comprising following steps:

• filling an inlet chamber with a flow of comminuted cellulosic material from a low-pressure zone;
• feeding the comminuted cellulosic material from the inlet chamber to the high-pressure zone with a motor driven feeding screw located in a feeding pipe, with an inlet end of said feeding pipe connected to the inlet chamber in the low-pressure zone and an outlet end of said feeding pipe in the high-pressure zone;
• such that the comminuted cellulosic material is transported from the inlet end towards the outlet end of the feeding pipe;
• arranging a restriction member in the feeding pipe reducing the flow section of the feeding pipe closer to the outlet end of the feeding pipe;
• characterized in that evacuating back blow pulses from the high-pressure zone from said feeding pipe in an intermediate position between the inlet end and the outlet end of said feeding pipe using a pressure relief outlet located in the wall of the feed pipe, further comprising preventing expansion of the plug of comminuted material into the pressure relief outlet by means of a screen member at the entry of the pressure relief outlet, i.e. in level with the wall of the feeding pipe.