Question

You are looking to design the first couple of units in a fermentation suite. The cells and product are particularly delicate. The cells need a substrate, S, that is extremely expensive. However we can make substrate S from a cheap reactant, A, and a slightly expensive reactant, B. At the end of the exam is a diagram of the whole system. Species A is continously fed into a reactor (Caf 1 mol/ vo 2 L/ s) initilly charged with species B (Nbo-10 mol, Vb-1 L), following the equation A + B S with elementary kinetics. Our reactor has dimensions of radius γ = 1 dm, and a height h = 5 drn. It is a spill- over reactor. This means that once it is completely full of liquid, it will begin to pour over the top. For the reaction, assume constant liquid-density a) What is the purpose of adding A into B, and not B into A? Without doing any computation or math, theoretically what should this conceptually maximize? b) Before spill over begins, what type of reactor will you employ for modelling? c) How long will it take for our reactor to completely fill? d) Once completely filled and it starts to drain, what type of reactor will you employ for modelling The cells are delicate, and must be grown at 37°C. At 20°C, the forward rate constant is and the reverse rate constant is k2 0.6 /s The activation energy -1.5 mol s divided by R, universal gas constant, for each constant is 750 Vx, and A2000 1/K. React and form the substrate at 37°C, so that it can be directly fed into the cell reactor without heat-shocking our cells. e) Using Matlab or Excel, prepare a mol vs time plot of what is happening in our first reactor. In the space below, write your species balances around A, B, and S before and after the critical time you found in c. f If you were trying to get the purest amount of S into the reactor, how long would you run the first reactor for? If you were trying to maximize the total amount of S in the system regardless of purity, how long would you run the first reactor for? The cells follow Monod growth. The yield and Monod constants you need are Pmax = 1.1 1/min ,K$ = 45 g/L' Yplc_ .45 g protes Xc/s-.85 9 substrate .The substrate has a molecular weight of MWs 150 moland the cell reactor was initially seeded at Cco 1. The cell reactor is 10 L in size g cells g) Prepare concentration vs time plots for substrate, cells, and protein until steady state is achieved. Species A and B are in this reactor, but for the sake of simplicity you can ignore A and B, and the reaction A+B+S The protein, remaining substrate, A, and B are fed to a 3d and final reactor (the cells are extremely dense and hang out towards the bottom of our 2 reactor, especially after agitation has stopped, everything else is suspended). Our buffer SuperAwesomeBuffer (SAB), freezes at-30°C. Species A, B, and S freeze at-20°C. To easily separate A, B, and S from the protein, we plan to freeze it to sucha temperature that A, B, and S solidify, but SAB stays liquid- freezing of the media will cause physical stress on the protein and denature it. All of the protein is sent to downstream where you deal with it in separations (CBE 442). A, B, and S are sent back to the substrate reactor; no more A is added, but the temperature is raised to 37℃ Reaction equilibrium is achieved prior to transportation back to the cell reactor. What temperature do you operate the freeze separator at? How many recycles must be done, in total, until we have achieved 99.99% conversion of the expensive reactant? h) substrate r reactor Protein cell reactor n recycles A, B, and S

Answer 1

cav) IC 2. 3 2OCC 2 Eacep