Mass-flow hopper

A hopper for containing and discharging particulate material, the hopper comprising:

• an upper converging section formed of:
• a first gas impermeable outer wall section having an exterior surface and an interior surface, and
• an upper frusto-conical gas permeable wall lining the interior surface of the first gas impermeable outer wall of the upper converging section, the upper frusto-conical gas permeable wall being spaced from the interior surface of the first gas impermeable outer wall of the upper converging section to define an upper space between the upper frusto-conically configured gas permeable wall and the interior surface of the first gas impermeable outer wall of the upper converging section, the upper frusto-conical gas permeable wall having a first slope,
• a lower converging section formed of:
• a second gas impermeable outer wall section having an exterior surface and an interior surface, and
• a lower frusto-conically configured gas permeable wall lining the interior surface of the second gas impermeable outer wall of the lower converging section,
• the lower frusto-conical gas permeable wall being spaced from the interior surface of the second gas impermeable outer wall of the lower converging section to define a lower space between the lower frusto-conically configured gas permeable wall and the interior surface of the second gas impermeable outer wall of the lower converging section, the lower frusto-conical gas permeable wall having a second slope,
• an intermediate connecting section between the upper converging section and lower converging section, wherein an upper end of the intermediate connecting section is in communication with a lower end of the upper converging section, wherein a lower end of the intermediate section is in communication with an upper end of the lower converging section, the intermediate connecting section formed of:
• a third gas-impermeable outer wall section having opposed upper and lower ends respectively connected to the first gas impermeable outer wall section and the second gas impermeable outer wall section,
• a discharge section defining a lower discharge opening for discharging solid particles from the hopper, wherein a lower portion of the lower converging section is in communication with the lower discharge opening;
• and
• wherein the upper frusto-conically configured gas permeable wall first slope is steeper than the lower frusto-conically configured gas permeable wall second slope,
• wherein the upper frusto-conically configured gas permeable wall is configured to fluidize material located above the upper frusto-conically configured gas permeable wall in a manner to facilitate passage of solid particles through the upper converging section to the intermediate section,
• wherein the lower frusto-conically configured gas permeable wall is configured to fluidize material located above the lower frusto-conically configured gas permeable wall in a manner to facilitate passage of the solid particles through the lower discharge opening of the lower converging section.