You are being tasked with completing a mass analysis on a novel process to conduct direct...

 

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You are being tasked with completing a mass analysis on a novel process to conduct "direct air capture" for a power plant that still burns fossil fuels, to try to remove as much carbon dioxide as possible from a stream that is 0.17% (1700 ppm) CO2 and the rest bulk air. Your separator can remove a fraction of the CO2 in this gas. Pure CO2 leaves in one outlet from the separator; the other stream is recycled, but part of the recycle stream is split as a purge. (a) Draw a process flow diagram representing this process. Even though there is only one physical "unit," the separator, please include a "split point" and "mixing point" where it would make sense to do so. (b) Complete a degree of freedom analysis of this process using only the information provided so far. How much more information is needed to fully solve for all the unknown values in this process? (c) The air that leaves this process has a target CO2 concentration of 0.028% (280 ppm, which is roughly how much CO2 was in the atmosphere prior to the industrial revolution). If this is true, for a basis of 10,000 lbm/hr of feed, determine the mass flow rate of the recycle stream for two scenarios: (1) the purge stream is 1/5 the flow of the recycle; (2) the purge stream is 1/10 the flow of the recycle. You are being tasked with completing a mass analysis on a novel process to conduct "direct air capture" for a power plant that still burns fossil fuels, to try to remove as much carbon dioxide as possible from a stream that is 0.17% (1700 ppm) CO2 and the rest bulk air. Your separator can remove a fraction of the CO2 in this gas. Pure CO2 leaves in one outlet from the separator; the other stream is recycled, but part of the recycle stream is split as a purge. (a) Draw a process flow diagram representing this process. Even though there is only one physical "unit," the separator, please include a "split point" and "mixing point" where it would make sense to do so. (b) Complete a degree of freedom analysis of this process using only the information provided so far. How much more information is needed to fully solve for all the unknown values in this process? (c) The air that leaves this process has a target CO2 concentration of 0.028% (280 ppm, which is roughly how much CO2 was in the atmosphere prior to the industrial revolution). If this is true, for a basis of 10,000 lbm/hr of feed, determine the mass flow rate of the recycle stream for two scenarios: (1) the purge stream is 1/5 the flow of the recycle; (2) the purge stream is 1/10 the flow of the recycle.