Which statement describes a recycle stream in process engineering terms?

Which statement describes a recycle stream in process engineering terms?

• A. Returning a portion of the product back to the reactor
• B. Heating the feed stream to the reactor
• C. Venting the reactor effluent to the atmosphere
• D. Removing solids from the feed

Answer: (A)

A recycle stream is material that is returned to an earlier point in the process to be reused. Returning a portion of the product back to the reactor creates a loop in which unreacted reactants and product are recirculated to undergo another pass, increasing overall conversion and helping to control temperature and composition while reducing fresh feed needs. The other statements describe actions that are not looping material back into the process: heating the feed changes its temperature, not its flow path; venting the reactor effluent wastes material; removing solids from the feed is a separation/pre-treatment step. Therefore, the description of returning product to the reactor best describes a recycle stream.

A recycle stream is material that is returned to an earlier point in the process to be reused. Returning a portion of the product back to the reactor creates a loop in which unreacted reactants and product are recirculated to undergo another pass, increasing overall conversion and helping to control temperature and composition while reducing fresh feed needs. The other statements describe actions that are not looping material back into the process: heating the feed changes its temperature, not its flow path; venting the reactor effluent wastes material; removing solids from the feed is a separation/pre-treatment step. Therefore, the description of returning product to the reactor best describes a recycle stream.