It is proposed to produce citric acid with a filamentous mould in a cylindrical 50 m fermenter. The following options are being considered for the choice of the fermenter: The fermenter is a stirred tank with a volume of 50 m. The fermenter has an equal tank height and tank diameter (HT = DT). It has a stirrer with a single Rushton turbine with a diameter Di; Di = 1/2 DT. The fermenter is a stirred tank with a volume of 50 m. The fermenter has a tank height which is twice tank diameter; H = 2DT. It has a stirrer with two Rushton turbines with Di = 1/2 DT. The fermenter is a stirred tank with a volume of 50 m. The fermenter has a tank height which is 3 times the tank diameter; HT= 3DT. It has a stirrer with 3 Rushton turbines with D = 1/2 DT. The cost of a fermenter increases with the number of turbines, and the number of turbines should therefore be kept as low as possible. The cost of a fermenter increases with the number of turbines, and the number of turbines should therefore be kept as low as possible. The power supply of the stirrer can only provide 15 kW. It can be assumed that the power consumption is equally divided over the turbines. Power P = NpND N = 5.5 if Re> 105; Re- PND, p= 1000 kg/m; = 1x10- Pas An additional requirement is that the tip speed of the impellers should not be higher than 2.5 m/s. Vp = N,D Tank number 1 (HT=DT) 2 (HT=2DT) 3 (HT= 3DT) DT (M) HT (m) D P (per impeller) N Vtip Re (b) Determine which fermenter should be chosen taking into account costs, power and tip speed. (c) The maximum oxygen consumption by the mould Qo is 30 mmol L-hr for a fully grown culture. Air is used to supply oxygen to the cells. The saturated oxygen concentration is 8 ppm. The critical oxygen concentration has been determined to be 2 ppm. Calculate the value of the kla (in s-) needed. Molecular weight O = 32 g/mol. pwater = 1000 g/L. (d) The medium is non-coalescing. The kla in such as medium can be predicted using: (d) The medium is non-coalescing. The kla in such as medium can be predicted using: All in Sl units. kla = 2.0 10-(P/v) 0.7u0 P is the power input, which in this case can be set at 15kW. V is the liquid volume of the tank, which in this case can be taken to be the same as the tank volume (50 m). Calculate UG, the superficial gas velocity (= gas velocity/cross sectional area of the fermenter) that was chosen. Calculate the air supply needed (in m/s).