Method and device for spraying a pulverulent material into a carrier gas

A device for spraying a pulverulent material into a carrier gas comprising:

• a pressurized carrier gas inlet
• a sonic throat convergent-divergent nozzle communicating with said pressurized carrier gas inlet
• a pulverulent material feed communicating with a negative pressure zone,
• means for expanding the carrier gas connected to said sonic throat convergent-divergent nozzle receiving the pressurized carrier gas and terminating in said negative pressure zone and
• an outlet structure of said pulverulent material entrained by said carrier gas outside the negative pressure zone, wherein said pulverulent material in said carrier gas has a flow rate,
• wherein the device for spraying further comprises a device for adjusting the flow rate of said pulverulent material in said carrier gas comprising a bypass circuit of said carrier gas equipped with a member for adjusting the amount of bypassed carrier gas, said bypass circuit comprising a carrier gas sampling structure placed upstream of said negative pressure zone of said carrier gas to bleed of an amount of sampled carrier gas and an orifice for reintroducing said amount of sampled carrier gas, wherein the orifice is located in said negative pressure zone, said sonic throat convergent-divergent nozzle being arranged to maintain, downstream, a constant flow rate of carrier gas entraining a predefined amount of pulverulent material.