ION EXCHANGE MODELING
Ion exchange is a widely used water purification process to control power plant water quality. Models are developed and applied for new demineralizer system designs and to evaluate the performance of existing systems. Two basic demineralizer designs are modeled:
Deep Bed Demineralizers
Deep bed demineralizer systems employing bead ion exchange resins have been evaluated using the Oklahoma State University Mixed Bed Ion Exchange (MBIE) model. This model has adjustable parameters that can be varied to simulate performance under a range of conditions. For instance, condensate polishing with condenser leaks of different magnitudes can be modeled for a given system. An example of extensive use of the model is in projecting the effects of an operation with condenser leaks at EPU (extended power uprate) conditions on effluent quality of condensate polisher operations.
Flow distribution within the demineralized vessel can be affected by the designs of the inlet flow distribution system and the underdrain system. CAD and hydraulic models are used to evaluate changes to optimize the flow distribution.
Filter demineralizers precoated with powdered ion exchange resin are used in many power plant water treatment applications. The ion exchange performance is particularly important in high purity water applications, such as condensate polishing and RWCU (reactor water cleanup). The radial flux profile along the length of the filter element must be taken into account to accurately project ion exchange performance. Silica removal efficiency is particularly sensitive to velocity.