ANS:B - Recycle stream/fresh feed stream

The recycle ratio in a chemical process is defined as the ratio of the Recycle stream to the Fresh feed stream. So, the correct option is: Recycle stream/fresh feed stream. The recycle ratio in a chemical process is a measure of the amount of material that is recycled back into the process compared to the amount of fresh material that enters the process.

1. Recycle stream:
   • This refers to the stream of material that is collected from the process output, treated if necessary, and then reintroduced into the process. Recycled material can include by-products, unreacted reactants, or other components that are separated from the product stream and reused.
2. Fresh feed stream:
   • This refers to the stream of fresh material that is introduced into the process. It typically consists of raw materials or reactants that are fed into the process to sustain or supplement the reactions or operations taking place within it.

The ratio of the recycle stream to the fresh feed stream provides insight into the extent to which material is being recycled within the process relative to the amount of fresh material being added. A high recycle ratio indicates that a significant portion of the material is being recycled, which can have implications for process efficiency, resource utilization, and environmental impact. Conversely, a low recycle ratio indicates that most of the material entering the process is fresh, with little being recycled. Overall, the recycle ratio is an important parameter in process design and optimization, as it influences material balance, energy consumption, and overall process performance.