Installation for distributing pulverulent substance by pneumatic transportation, comprising a device for depressurizing a pressurized reservoir in which said substance is stored

An installation for distribution of granular or powder material via pneumatic transport comprising at least one dispensing hopper for temporary storage of said granular or powder material, the dispensing hopper being suited to being, alternately, pressurized for emptying the dispensing hopper and depressurized to permit filling thereof, and a device for depressurizing said dispensing hopper, comprising

• a first depressurizing duct connected to said dispensing hopper,
• a bag filter, having a maximum operating flow rate of a gas flow from the dispensing hopper, connected to said first depressurizing duct,
• a second depressurizing duct extending from said bag filter, said second depressurizing duct configured to receive a dedusted gas flow from said bag filter;
• and
• flow control means for controlling the flow rate through the bag filter,
• wherein the bag filter is a filter suited to operating under pressure, and the flow control means are static control means without moving elements, disposed in the second depressurizing duct downstream of the bag filter and configured to receive the dedusted gas flow, the flow control means comprising a plate with an orifice of predetermined cross-section or a de Laval nozzle of a predetermined cross-section and shape, arranged to permit the passage of a maximum volumetric flow rate which is less than or equal to the maximum admissible flow rate for the bag filter.

A blast furnace installation structured for injecting granular or powder material into the blast furnace comprising

• at least one dispensing hopper structured for temporary storage of said granular or powder material, the dispensing hopper being configured to pressurize and to depressurize alternatively, and
• a device structured for depressurizing said dispensing hopper, comprising
• a depressurizing duct connected to said dispensing hopper,
• a bag filter, having a maximum operating flow rate of a gas flow, connected to said depressurizing duct, and
• flow control means for controlling the flow rate in said depressurizing duct through the bag filter,
• wherein the bag filter is structured to operate at a pressure up to 25 bar, and the flow control means are static control means without moving elements, are disposed in the depressurizing duct downstream of the bag filter, and are configured to receive the gas flow, and
• wherein the flow control means comprise a plate with an orifice of predetermined cross-section or a de Laval nozzle of a predetermined cross-section and shape, arranged to permit the passage of a maximum volumetric flow rate which is less than or equal to the maximum admissible flow rate for the bag filter.