chemical engineering Caffeine is often added to headache medications because it
ID: 532647 • Letter: C
Question
chemical engineering
Caffeine is often added to headache medications because it affects the flow of blood in vessels and may enhance the pain relieving qualities of the medication. You have been tasked with evaluating one process that extracts caffeine from a coffee slurry, and you decide to study a small scale version of the process. A Coffee slurry containing a mass fraction of 0.01 g caffeine/g, 0.08 g other solids/g, and 0.91 g waterig is fed to a mixer at a rate of 570.0 g/min. Na2CO3 is added to the mixer such that the mass ratio of Na2CO3 to coffee slurry is 0.0450. This aqueous solution proceeds to an extractor where CH20lz is added such that the mass ratio of CH2Cl2 to coffee slurry entering the extractor is 0.290. Two streams leave the extractor The first is a mostly aqueous stream that leaves the process containing some caffeine, all of the other solids in the original slurry, all of the Na2CO3, all of the water and 2% of the mass of CH2Cl2 entering the extractor. The second stream contains the remaining caffeine and CH2Cl2, and enters an evaporator that completely vaporizes the CH2Cl2. The vaporized CH2Cl2 is condensed and is merged with the fresh CH2Cl2 on the way to the extractor. The dried caffeine crystals exit the evaporator and leave the process. Of the caffeine entering the process a fraction of 0.950 leaves the process in this product stream. abel the process flow diagram below. abel any quantities as "unknown" if you have to perform a calculation to obtain the num value. DONOT LEAVE ANY SPACE BLANKExplanation / Answer
Feed to the mixture = 570 g/mmin. It contains 0.01g caffeine/g, 08 g other solids/gm and 0.91 water/g.
Feed contains : Caffeine= 570*0.01= 5.7 g/min, other solids= 570*0.08=45.6 g/min and rest water= 0.91* 570= 518.7 g/min
Given the mass ratio of Na2CO3/ coffee slurry= 0.045
Mass flow rate of Na2CO3= 0.045*570= 25.65 g/min
Mass flow rate of slurry entering the extractor = 570+25.65 =595.65 g/min
It is given that CH2Cl2 is added such that the mass flow rate of CH2Cl2/slurry entering the extractor = 0.290, mass flow rate of CH2Cl2 entering he extractor= 595.65*0.290=173 g/min. this is m5.
Caffeine removed from evaporator= 0.950* 5.7= 5.415 g/min
Caffieine in the aqueous stream= 5.7-5.415= 0.285 g/min
The aqueous stream from the extractor contains all the solids entering. Flow rate of solids in the aqueous stream = 45.6 g/min, Na2CO3 in the aqueous stream = 25.65 g/min, water= 518.7 g/min, CH2Cl2= (2/100)*173= 3.46 g/min. since this is leaving along with aqueous stream, this ithe amount that need to be added fresh.
Aquesous stream total flow rate= 0.285(Caffeine)+ 45.6 (solids)+ 25.65 (Na2CO3)+ 518.7 (water)+3.46 (CH2Cl2)=593.7 g/min
Composition : Caffeine = 0.285/593.7=0.00048, solids= 0.077, Na2CO3= 25.65/593.7=0.043, water= 518.7/593.7=0.873, CH2Cl2= 3.46/593.7= 0.0058
Recycle CH2Cl2 flow rate= total CH2Cl2 entering- CH2Cl2 added fresh = 173-3.46=169.54 g/min
Recycle flow rate of CH2Cl2/ fresh CH2Cl2= 169.54/3.46= 49
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