Static mixer arrangement with dosing module for supplying liquid additive into mixer, has oscillating single-head dosing pump for additive stream with defined stroke number to ensure pulse-free supply

摘要

In a mixer arrangement comprising a static mixer (1) and a dosing module (12) for continuously supplying a liquid additive into the mixer, where the module includes an oscillating single-head dosing pump (7) for the additive stream, the minimum stroke number of the pump (7) is defined in relation to maximum allowable main stream flow rate and the mixer diameter by a mathematical equation. A mixer arrangement comprises a static mixer (1) and an additive dosing module (12) for ensuring continuous, controlled and monitored supply of a liquid additive into the mixer. The dosing module includes a flow monitor (9) in an additive stream (9), upstream of an oscillating single-head dosing pump (7) with at least one excess pressure protector (6); and a shut-off fitting (5) in the additive stream. In the mixer arrangement: (A) the minimum stroke number (Hmin), in strokes per second, of the pump (7) is given by the mathematical equation: Hmin = uz max/(18.129 x Bo-0.7578 x D) (where uz max is the maximum allowable main stream flow rate in m/s; Bo is the Bodenstein number; and D is the diameter of the first stage of the mixer); (B) the static mixer extends over the length (L) of at most five different diameter measurements (D, D1); and (C) the dosing module is connected to the mixer by a tube (13) with at most five inoculation sites before the mixer. An independent claim is included for a tube arrangement with a static mixer and dosing module as above, where the mixer is incorporated in the tube arrangement and the tube arrangement includes backflow region with at pump in at least one site between the start and end of the tube arrangement.