A purification system with recycle isused to recover the solvent DMF from a waste gas containing 55 mol% DMF. The product is to have only 5 mol % DMF. The purificationunit can remove three-fourths of the DMF from the combined feed tothe unit. Calculate the mol fraction of DMF entering thepurification unit and the recycle ratio (recycle ratio = moles inrecycle/moles in feed).

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Methanol is synthesized from carbon monoxide and hydrogen in a catalytic reactor. The fresh feed to the process contains 32% MOL CO, 64% H2, and 4% N2. This stream is mixed with a recycle steam in a ratio 5 mol/1 mol fresh feed to produce the feed to the reactor. The reactor effluent goes to a condenser from which the two streams emerge: a liquid product stream containing essentially a the methanol formed in the reactor, and a gas stream containing all the CO, H2, N2 leaving the reactor. the gas stream is split into 2 fractions: one is removed from the process as a purge stream, and the other is the recycle stream that combines with the fresh feed to the reactor. QUESTION: FOR A METHANOL PRODUCTION RATE OF 100 KMOL/H, CALCULATE THE FRESH FEED RATE (KMOL/H), THE MOLAR FLOWRATE AND COMPOSITION OF THE PURGE GAS, AND THE OVERALL AND SINGLE PASS CONVERSION.

ANSWER: MOL BASIS 600 MOL. 78 MOLES OF NITROGEN COMES FROM FEED ( 4 MOLES) AND THE RECYCLE STREAM (74 MOLES).

FEED: CO 131.6 KMOL/ HR

WATER: 263.2 KMOL/ HR

NITROGEN: 16.45 KMOL/ HR

Ethanol is produced commercially by hydration of ethylene and during this process a side reaction converts some the ethanol to diethyl ether (DEE).

In one process, a fresh feed containing ethylene, non-condensable inerts, and water are mixed with a recycle stream. The combined stream is fed to the reactor and it contains 182 mol/min of ethylene. While the fresh feed contains 9 moles of ethylene per mole of inerts, after mixing with recycle stream, the mole ratio of inerts to ethylene changes to 0.23. The water to ethylene mole ratio in the input to the reactor is 0.6. The single pass conversion of ethylene in the reactor is 0.23 and the molar selectivity of ethanol to ether is 14.

To recover the ethanol and DEE, the gaseous output from the reactor is sent to a condenser. Here, 93% of the three species - ethanol, DEE, and water - fed to the condenser are removed as a liquid product stream. None of the ethylene and inerts leave in the liquid. A second output from the condenser is the gas mixture and this is split into a purge and the recycle that mixes with the fresh feed.

Solve the material balance for the process and choose the correct option below.

A/ ethylene in fresh feed is 66.7 mol/min

B/ ethanol in product leaving the condenser is 41.6 mol/min

C/ recycle to purge ratio is 3.95

D/ Two choices, A and B, are correct

E/ The three A-B-C choices are all correct

Synthesis gas for ammonia manufacture is fed to a reactor with N2 and H2 in stoichiometric ratio.The N2 stream to the synthesis process which produces the synthesis gas contains argon in the ratio of 1 mol Ar/78 mol N2. The single-pass conversion of the ammonia reactor is 23%. All the ammonia in the product stream is separated by condensation and the unreacted gas is recycled. From experiments, you found that, in order for the process to work properly, it is necessary to have a vent stream from the recycle line which amounts of 0.02 moles per mole of synthesis gas fed to the system. Determine:a) the mole percent argon in the fresh synthesis gas feed; b) the recycle/synthesis gas flow ratio; and c)the overall conversion for the process.

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