Material balance with recycles

The reactor and separation systems described above can be assembled in a flowsheet In a preliminary simulation, the goal is closing the material balance with recycles. In a first approach shortcut models may be used to simulate the distilla-... 

The central issue in performing the material balance with recycles is the behaviour of the reaction system. Besides conversion, a design variable inherited from the previous level, the molar reactant ratio becomes now a design variable, which will affect the flow rate of the recycle streams. Note that the assumption of 100% overall recovery of unconverted reactants is maintained. 

Tables of material balance with recycles have been prepared for different conversions of toluene with yp as parameter. Fig. 7.10 displays gas-recycle flow rate against conversion for hydrogen purge concentration of 0.1, 0.4 and 0.7. The plot shows a large variation of the gas flow rate with conversion, over several orders of magnitude, for the concentration of H2 in purge between 0.1 and 0.7. Therefore, it is rational to work at higher conversion, but also with substantial excess in hydrogen.

Simple combinations of reactor elements can be solved direc tly. Figure 23-8, for instance, shows two CSTRs in series and with recycle through a PFR. The material balances with an /i-order reaction / = /cC are... 

MATERIAL BALANCE—LINKING RECYCLE AND PURGE WITH REACTION SELECTIVITY AND CONVERSION 2.10... 

An additional separator is now required (Fig. 4.2a). Again, the unreacted FEED is normally recycled, but the BYPRODUCT must be removed to maintain the overall material balance. An additional complication now arises with two separators because the separation sequence can be changed (see Fig. 4.26). We shall consider separation sequencing in detail in the next chapter. 

Closed-Circuit Milling In closed-circuit miUing the taiUngs from a classifier are mixed with fresh feed and recycled to the miU. Calculations can be based on a material balance and an expUcit sohi-... 

The material balance in a constant volume chemostat is derived based on cell balance as shown in the following equations. Material balance in a chemostat with recycle, pcell ... 

The material balance around the mixing point of a loop reactor is given by Equation (4.21) for the case of constant fluid density. How would you work a recycle problem with variable density Specifically, write the variable-density counterpart of Equation (4.21) and explain how you would use it. 

The objectives of this study were to compare the yields of cold-pressed essential oil, water consumption, material balance and efficiency of the process in a typical citrus peel oil recovery plant with and without recycling system. The different emulsions and aqueous discharges from these processes were also characterized. 

Material balance calculations on processes with by-pass streams are similar to those involving recycle, except that the stream is fed forward instead of backward. This usually makes the calculations easier than with recycle. 

Sherrington (S10) has presented a static model of the granulation loop operating in the snowballing mode. The model combines the solution phase theory in Eq. (106) with the material balance across the granulator. The recycle ratio defined as recycle/raw solid feed, is given by... 

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