Abstract: The invention relates to a device for spraying particles of dry ice, notably for the purpose of cleaning surfaces, comprising a spray nozzle (4), allowing the passage of a working fluid carrying said particles, said nozzle (4) having an outlet orifice (5) and comprising a throat (6) and a divergent part (7) said divergent part (7) extending between the throat (6) and the outlet orifice (5) of the nozzle. According to the invention, said divergent part (7) has at least one first stage extending between the throat (6) and an outlet orifice of said first stage (5, 12) and the ratio between the area of the throat (6) and the area of said outlet orifice (5, 12) of the first stage of the divergent part is greater than 0.2.

Abstract: Fuel-fired furnace and a method for operating it, in which method: a main oxidizing agent is injected at a controlled flow rate into the combustion chamber of the furnace; the combustible material is burnt in the combustion chamber with the main oxidizing agent, producing thermal energy and flue gases at a temperature higher than 600° C.; the flue gases are removed via an exhaust duct, said removed flue gases possibly containing residual materials that could be oxidized, the exhaust duct being equipped with an inlet for a diluting oxidizing agent downstream of the combustion chamber; the residual materials that could be oxidized are burnt with the diluting oxidizing agent by means of a flame at the inlet for the diluting oxidizing agent; the flame intensity inside the exhaust duct is detected; and the flow rate at which the main oxidizing agent is injected into the combustion chamber is controlled according to the detected flame intensity.

Abstract: The invention relates to a method of operating a furnace (1) comprising a flue pipe (11) for discharging the smoke, means (19) of introducing ambient air into the said flue pipe (11) and a smoke extractor (16) arranged in the said flue pipe (11). According to the method, the temperature of the smoke is measured at two points (31, 33), the temperature measured at the second point (33) is subtracted from the one measured at the first point (31), the result of the subtraction is compared with a datum value &Dgr;T, and the ratio of the flow rate of fuel to the flow rate of oxidizing agent introduced into the furnace (1) is decreased when the result of the subtraction is below the datum value &Dgr;T.

Abstract: Device for protecting an ejection outlet of a burner mounted through a wall of a furnace, comprising a peripheral heat shield around the ejection outlet of the burner comprising a consumable structure comprising a refractory material and a mounting for heat shield comprising a mover which moves the heat shield relative to the wall of the furnace, between at least two positions which are spaced apart along the axis of the burner.