CFD Analysis for Eductor in Neutralization Pit of Wastewater
In this Water Treatment Simulation Consultancy project, the process of the purifying plant needed to controlling the pH value of Industrial waste water.
Solution of NaOH (base) and HCl (acid) is supplied through three educators to achieve the pH level. Neutralization pit has been developed to mitigate this.
The wastewater from compartment A is circulated to compartment B and/ C till desired pH value. The numerical analysis has been carried out to find out the mixing characteristics in neutralization compartment (i.e. B/C).
CFD Model of Neutralization Pit
Flowrate Calculations over Single Eductor
Numerical Model, Operating Conditions & Boundary Conditions
Three cases perform – A to B , A to B+C (62.56psig) and A to B+C (56.07psig)
Results and Discussion
The numerical analysis has been carried out for all three CASES for 1200 secs to find out the mixing characteristics in neutralization compartment, two phase model has been utilized i.e. wastewater in tank 1 is phase 1 and wastewater coming in the tank as phase 2. Therefore, the volume fraction of two phases in the compartment provides the mixing characteristics very well. The min. waste water level is achieve in CASE [II]:A to B + C
It can be concluded that, calculated flow rate has sufficient potential to deliver the required momentum for mixing at the vertical position (i.e. 0.45 m.) of all eductors i.e linear mixing.
Stagnation zones have been observed at each corner as well as at the back of the eductors.
To counter the stagnation occurred from given eductor positions, it is desirable to change the horizontal position.
The liquid mixer is ideal benchmark to optimize the mixing in the compartment. The utilization of all three eductors should produce mixer type effect.
The use of baffles at optimized location in the compartment also enhance the mixing in the compartment.