Stream Splitting at the Pinch

Similar to the design of HENs, when matching rich and lean streams at the pinch, on the rich side, it is necessary that the number of rich streams be less than or equal to the number of lean streams. When this is not the case, lean streams must be split until the number of rich and lean streams is equal. Also, on the lean side, it is necessary that the number of lean streams be less than or equal to the number of rich streams. Here, rich streams must be split until the number of rich and lean streams is equal. The development of MENs above and below the pinch, including the need for stream splitting, is illustrated in the next example. 

EXAMPLE llJt H S Removal from Sour Coke Oven Gas (Examples 11.1 and 11.2 Revisited) 

As discussed earlier, the capacity of stream LI to remove solute exceeds the solute in steams R1 and R2 by 0.002665 kg/s. Rather than add solute to the rich streams, it is assumed that the flow rate of stream LI can be reduced accordingly. Consequently, stream LI is adjusted to remove 0.06946 -0.002665 = 0.06680 kg/s of solute. Its adjusted flow rate is 

inequality (11.13) is checked for each potential match on the rich side of the pinch  

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