Fluid control system in pneumatic conveying ducts for powdered or granular material

A fluid control system in a pneumatic conveying duct for powdered or granular material, comprising:

• a conveying duct inside which the powdered or granular material is conveyed;
• a plurality of supply sources of respective pressurized gases for transporting said powdered or granular material inside said conveying duct;
• a plurality of injection lines of said gases to respectively put the supply sources in fluid communication with said conveying duct;
• a plurality of self-regulating pressure valves arranged respectively on the injection lines between the respective supply sources and said conveying duct;
• a plurality of control members respectively operatively connected to the self-regulating pressure valves to respectively provide command signals, representing pressure values, to the self-regulating pressure valves, each of the self-regulating pressure valves maintaining constant gas flow values supplied in said conveying duct;
• a plurality of flow and flow rate meters, respectively arranged on the injection lines upstream of the self-regulating pressure valves to transmit a-flow and flow rate values to the control members;
• a plurality of pressure meters arranged respectively on the injection lines downstream of the self-regulating pressure valves and close to the conveying duct to respectively transmit pressure values to the control members,
• the control members determining pressure and/or flow parameters regulated by the respective self-regulating pressure valves depending on pressure values detected by the pressure meters.