Kakashi-01
Chemical
- Mar 29, 2024
- 15
(7a and 7b) and (12a and 12b) are streams that undergo a phase change. I have broken Stream 7 into two dummy streams, one representing the stream as it is cooled to its dew point and the other representing the stream as it is further cooled to its desired temperature. Same goes to stream 12. Streams 17 and 18 represent the streams that pass through the column reboiler and condenser. I didnt break down those streams because their temperature change while they phase change is minimal
I adjusted the temperatures of the hot and cold streams, rank each temperature in descending order and calculated the enthalpy of each temperature interval. An enthalpy cascade was designed. In the initial pass, no heat was added from outside. The residual enthalpy was always positive indicating no process pinch. However, looking at the composite curve there is a psuedo-pinch temperature at 142.4996427 C. The design for the heat exchanger network should start from the psuedo-pinch and move away from it.
Above the psuedo-pinch, it must follow that the number of hot streams be less than the number of cold streams and CPH<=CPC to pair hot and cold streams. But, why do I have to split the streams? Looking at the data all the hot streams can satisfy the cold streams above the pseudo-pinch to the no utility end. Namely, stream 21 can be matched with cold streams 5,10,and 19 and stream 7a can be matched with stream 17 in the reboiler satisfying their duties and not violate the minimum temperature difference.
I adjusted the temperatures of the hot and cold streams, rank each temperature in descending order and calculated the enthalpy of each temperature interval. An enthalpy cascade was designed. In the initial pass, no heat was added from outside. The residual enthalpy was always positive indicating no process pinch. However, looking at the composite curve there is a psuedo-pinch temperature at 142.4996427 C. The design for the heat exchanger network should start from the psuedo-pinch and move away from it.
Above the psuedo-pinch, it must follow that the number of hot streams be less than the number of cold streams and CPH<=CPC to pair hot and cold streams. But, why do I have to split the streams? Looking at the data all the hot streams can satisfy the cold streams above the pseudo-pinch to the no utility end. Namely, stream 21 can be matched with cold streams 5,10,and 19 and stream 7a can be matched with stream 17 in the reboiler satisfying their duties and not violate the minimum temperature difference.
