Oftentimes, during the design of a new process, it is required that we either dilute or concentrate a process stream by mixing it with another stream. As typically a designer will have a goal in mind for the mixing, the flowrate of the mix-in inlet has to be determined during simulation. This model will allow users to express such process design constraints directly. Note that 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 mass flowrate is set to a value that turns out to be lower than the process (bottom) stream’s flowrate.
2. The output volumetric flowrate is set to a value that turns out to be lower than the process (bottom) stream’s volumetric flowrate.
3. The concentration (or mass fraction) of the design component set for the output stream does not fall in between the concentration (or mass fraction) of the same component in the process (bottom) stream and the adjustable mix-in.
If any of the above conditions is detected during simulation, a warning message will appear. In order to remedy the situation, you must either relax the mixing specification or adjust some process conditions upstream that will change the flowrate and/or the concentration/mass fraction of the design component in the process input stream.
If the equipment size option is in Design Mode and the operating throughput exceeds the maximum throughput, then, the program assumes 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 Custom Mixing: Oper. Conds Tab
● Utilities, see Throughput Operations: Utilities 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