1. The problem statement, all variables and given/known data The problem want me to do a degree of freedom analysis on the following process using the information provided. There are two chemical rx in the process. The desired production rate of DEA (D) is 105,000 kg/h. The air composition is 21% mol% O2 and 79 mol% N2[/SUB. 25% of ethylene (E) is converted in the first reaction. 2. Relevant equations DOF = # of independent variables - # of independent equation 3. The attempt at a solution When doing the problem, I put all the process units into one system and drew an overall diagram below. For my DOF analysis of the bottom system to match the table in the top, I had to include the recycled stream, #10. Otherwise, I would be one stream variable short and get a DOF of -1. So my question is was it right to include the recycled stream when putting all the process units into one system? For the bottom system, I had 9 independent variables (7 stream variables + 2 chemical rx) and 9 independent equations (1 flow, 1 stream composition, 1 system performance, and 6 material balance equations).