Water Journal : Water Journal September 2015
water september 2015 48 Feature article be a third party consultant, or work in-house on design software, with licence restrictions. Design reviews are not usually held until initial mass balance and flowsheets have been developed. As project and process engineering teams generally work separately to the commercial team, communicating direct client understanding can get lost in translation, sometimes resulting in multiple rounds of design revisions until the team comes to a consensus. Process engineers are usually too busy during a tender to reliably model all membrane types and boundary conditions with vendor projection software. Locking down a concept design quickly to enable handover to mechanical and electrical engineers for their design tasks is the highest priority. As each case can only be modelled sequentially, input errors or revised configurations result in repeating rounds of projections delaying the tender’s progression. Team stress levels grow as the rounds of revisions to the design increase, and time to deliver a quality concept design decreases. Membrane selection may not always be necessary before commencing mechanical or electrical design; however, choosing the right membrane type and configuration may have advantages to power and chemical consumption that will influence the cost of the project. Also, making a decision much earlier in the bid cycle can buy valuable time for vendor equipment pricing and negotiations. This could all lead to better productivity and, ultimately, to lower project cost for the client or healthier margins for the bid consortium. an Integrated concePt desIgn Salt Water has developed an online SaaS (Software as a Service) platform for process simulation and concept design of physico- chemical water treatment facilities that addresses many of the current deficiencies outlined above. The aim of the AqMBTM (Aqueous Mass Balance) software is to streamline the water treatment design process and allow simultaneous comparison of products from major membrane and resin manufacturers for integrated process design. Users can configure multiple trains, compare membrane types in parallel and run multiple models simultaneously, reducing concept design time. With each unit operation configured in the platform’s Design Mode, AqMB will size the equipment according to user-adjustable process design parameters such as design flux and lead element flux for first pass design on all RO feedwater scenarios. The user can revise the array configuration and membrane type based on a review of permeate quality or performance parameters such as feed pressure, stage differential pressure or concentrate flow. Process design and equipment sizing can be finalised in a matter of hours instead of weeks. AqMB uses a deterministic modelling approach and has been designed for steady-state water treatment applications involving conventional and emerging technologies, and includes chemical dosing, settling, filtration, membrane, ion exchange resin, and electrolytic and thermal processes. Currently 22 out of 36 unit operation models have been added, and a time-series modelling feature is scheduled for release in late 2015. Users sign up and access the platform via the AqMB website using a single sign-on authentication. Users are then directed to their personal Overview page. This page includes previous plants created by the user, shared plants from other registered users within their company, feed scenarios and previous results from modelling different plant/feed scenarios. Upon executing a model run, the platform calculates the solubility of each stream using kinetic, redox and equilibrium relationships as defined by key water quality parameters, while accounting for the activity (deviation from ideal) of each species in solution. The execution time to solve a model typically takes from a few seconds to several minutes, depending on the complexity of the process and the number of water quality analytes in the feedwater. Figure 2. Water input table within Aqmb – up to five analyses can be modelled with each scenario.
Water Journal August 2015
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