In this post, I want to share how to calculate material balances using the system boundary approach. This method is especially useful when dealing with a process configuration that involves several types of equipment with a different function, such as reaction, filtration, drying, and recycling.
How to do it?
We need to divide the overall process into several process sub-division or system boundaries. The flows into and out of the system are those crossing the sub-division and must balance with material generated or consumed within the boundary.
There are no rigid rules to use this approach. Selection of the best sub-division for any process is from our judgement and by practice a lot. However, these general rules can be used as a guide to calculate material balance using the system boundary approach:
- For complex processes, first thing to do is to take overall complete process and if possible, calculate the flows in and out. Raw materials in, products, and by-products out.
- Select the boundaries to sub-divide the process into simple stages and make a balance over each stage separately.
- Select the boundary round any stage to reduce the number of unknown streams to as few as possible.
- Include any recycle streams within the system boundary.
Let’s see example below to practice. Read More