METERING DEVICE FOR INTRODUCING A LIQUID ADDITIVE INTO A STREAM OF MAIN LIQUID

摘要

Metering device for introducing a liquid additive into a main liquid flowing along a pipe, includes a pump for withdrawing additive from a container and metering it, this pump including a first inlet for receiving a flow of main liquid which drives the pump, a second inlet for picking up additive and an outlet for the resulting mixture; a Venturi installed in the pipe, and connected in parallel with the pump, the first pump inlet connected by a first line to the Venturi inlet while the outlet connected by a second line to the Venturi throat; a first element for varying the restriction at the Venturi neck, and a second element sensitive to the pressure drop across the pump for controlling the first element to reduce the bore section when the pressure drop across the pump increases, and increase the bore section when the pressure drop across the pump decreases.

主权项

1. A metering device for introducing a liquid additive into a stream of main liquid flowing in a pipe, the device comprising a reciprocating differential piston pump (3) for taking up the additive in a container and metering it, this pump comprising a first inlet (8) for receiving a main liquid flow that drives the pump, a second inlet (9) for taking up the additive and an outlet (10) for mixing the additive and the main liquid, the device comprising a venturi (11) arranged in the pipe, the pump (3) being connected in parallel with the venturi (11), the first inlet (8) of the pump being connected via a first line (12) to the inlet of the venturi while the outlet (10) of the pump is connected via a second line (13) to the throat (11c) of the venturi, wherein the device comprises:
a means for varying the constriction (E) of the throat (11c) of the venturi, and a means (G) sensitive to the pressure drop in the pump (3), which means is able to control the means for constricting (E) the throat of the venturi to reduce the passage cross section when the pressure drop in the pump increases, and to increase the passage cross section when the pressure drop in the pump decreases.