Your goal can be accomplished to an extent. In the 80's I developed material balances for the ammonia process using complicated Lotus 1,2,3 spreadsheets for designing grassroots plants. You will need an understanding of how your variables affect results and code the mathematical relationships. You will also need at least one accurate material balance for checking your program. If you use that balance for tuning, then you should have at least one other balance for the checking. Calculating changes in the loop reactor itself will be difficult due to their complex geometry, so first assume a fixed percentage conversion to get the rest of the loop correct. If I were to attempt your task, I would search on the web for references. Academic thesis work for the ammonia process was common and often contains useful material balances if you have no better resource.
If you are interested in the fascinating history of the ammonia process (the birth of chemical engineering) I recommend the book 'The Alchemy of Air' by Thomas Hager which traces the story of Fritz Haber and Carl Bosch. The mass production of ammonia averted worldwide starvation allowing the population growth we have seen in the past 100 years.