Expert Water Treatment Plant Design
Thames Water Utilities, UK
Thames Water has been using CFD since 1992, for new equipment design and trouble-shooting, to ensure successful scale-up and generally to improve understanding of treatment processes. CFD started within the R&D environment at Thames, but is now also used in the Engineering Department where its benefits in solving real day-to-day problems easily justify its cost.
Thames has studied a channel which is used to distribute the flow from four bellmouth inlets. As one third of the cost of building a water treatment plant is spent on water channelling, it is important that new designs meet the required performance criteria - in this case assuring even distribution of flow to the outlets.Where geometrical complexity precludes the use of normal engineering rules of thumb, CFX is used to calculate the flow distribution and check on the applicability of the design. Here, internal baffles were required to balance the flow at the outlets, and CFX was used to investigate and optimise their design.
Flow distribution from four bell mouth inlets
In another study,Thames used CFX to calculate the flow delivered to a counter current dissolved air flotation unit .This device is used to remove algae from the water, and for correct operation, variation of the flow at the cones must be within 5% of the mean.The engineers used CFX to optimise the design and obtain the required uniformity by varying the orifice dimensions at each outlet. CFD analysis is now a fundamental part of Thames Water’s design cycle. Other areas where it is used include raw water reservoir studies, rapid mixing in pipes, flocculation, ozone and disinfection tanks, sedimentation and clean water reservoirs.
Inlet flow system delivering to a COCODAFF unit