In some cases during the design of a new process, it is required that we maintain a process stream at a certain pH level. This model will allow users to achieve such process design constraints directly. Clearly, the composition of the adjustable add-in stream must be set by the user before the simulation starts.
Under certain circumstances, the model will fail to determine a value for the adjustable mix-in stream that will meet the constraint set by the user. These circumstances are described below:
1. The output target pH is not within the range of the pH of the process and adjustable inlet streams.
2. The pH of the process inlet stream is the same as the one of the adjustable stream.
If any of the above conditions is detected during simulation, a warning message will appear. n order to calculate the pH of an aqueous solution containing multiple different species, a system of nonlinear algebraic equations must be solved simultaneously. The procedure is described in the chapter 4 section pH Calculation of Bulk Streams.
If the equipment size option is in Design Mode and the operating throughput exceeds the maximum throughput, then, the program assigns multiple, identical units operating in parallel with an operating throughput of less than the maximum. If the equipment size option is in Rating Mode and the operating throughput exceeds the rated throughput of the step (which is equal to the rated throughput of each unit times the number of units), a warning message is displayed advising the user to increase the number of units or reduce the operating throughput.
The interface of this operation has the following tabs:
● Oper. Cond’s, see pH Regulation (Cont): Oper. Conds Tab
● Reactions, see Stoichiometric Reaction/Fermentation Operation: Reactions Tab
● Vent/Emissions, see Reaction Operations: Vent/Emissions Tab
● Labor, etc, see Operations Dialog: Labor etc. Tab
● Description, see Operations Dialog: Description Tab
● Batch Sheet, see Operations Dialog: Batch Sheet Tab
● Scheduling, see Operations Dialog: Scheduling Tab