Log in
Chemistry
1
answer
0
watching
257
views

A purification system with recycle is used to recover the solvent DMF from a waste gas containing 60% DMF in air. The product is to have only 10% DMF. Calculate the recycle fraction (the ratio of the molar flowrate of the recycle stream to the molar flowrate of the pure DMF stream leaving the purification unit) assuming that the purification unit can remove two thirds of the DMF in the combined feed to the unit.

Watch
1
answer
0
watching
257
views

For unlimited access to Homework Help, a Homework+ subscription is required.

Robert Kubara
Robert KubaraLv10
10 Feb 2021

Unlock all answers

Get 1 free homework help answer.
Already have an account? Log in
Share
discord banner image
Join us on Discord
Chemistry Study Group
Join now

Related textbook solutions

Basic Chemistry
5 Edition,
Timberlake
ISBN: 9780134138046
Principles of Chemistry Molecular Approach
4th Edition,
Tro
ISBN: 9780134112831
Chemistry: Structure and Properties
2nd Edition,
Tro
ISBN: 9780134293936
Principles of Chemistry Molecular Approach
3rd Edition, 2014
Tro
ISBN: 9780321971944
Chemistry: A Molecular Approach
3rd Edition,
Tro
ISBN: 9780321809247
Chemistry: A Molecular Approach
5th Edition,
Tro
ISBN: 9780134874371
Principles of Chemistry: A Molecular Approach
4th Edition,
Tro
ISBN: 9780134895741
Chemistry: The Central Science
14th Edition, 2017
Brown
ISBN: 9780134414232

Related questions

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

Serine (MW 105) is to be recovered from an aqueous solution containing 30% (w/w) serine. In one steady state process, a fresh feed of 100 lbm/hr of this aqueous solution is mixed with a recycle stream (first recycle) and sent to a separator that removes only water selectively by a process of pervaporation. In the pervaporation unit, approximately 51.35 lbm/hr of water is removed to concentrate the solution such that the output contains approximately 9 lbm of serine for every 11 lbm of water.

To facilitate crystallization, addition of methanol is performed. A fresh feed of methanol containing a non-volatile impurity is used. This impure fresh feed is mixed with a recycle stream (second recycle) of pure methanol, which brings the impurity content of the resulting stream to 0.5% (w/w). The resulting mixed stream is then combined with the output from the pervaporation unit before being sent to a crystallizer-filter unit. In this unit, pure solid crystals of serine monohydrate are recovered as primary product. The filtrate is sent to an evaporator unit that separates out only methanol as vapor; 80% of the methanol input to the evaporator is recovered as vapor. This vapor is condensed and is the basis of the second recycle that mixes with the impure methanol feed. The liquid stream from the evaporator containing unrecovered methanol and other constituents forms the basis of the first recycle stream that is mixed with the fresh feed of serine solution.

It is found that 80% of the serine in the fresh feed is recovered in the primary product stream of crystals from the process. To achieve this recovery, the combined stream sent to the crystallizer-filter unit has to be controlled to contain 2.5% (w/w) of the impurity.

Note: use MW of water as 18

What is the total mass flow of the stream input to the pervaporator unit in lbm/hr?
What is the wt% of serine in the purge stream?
What is the wt% of serine in the stream input to the pervaporation unit?
What is the ratio of flowrates for recycle to purge?
What is the total mass flow of the recycled methanol in lbm/hr?
What is the wt% of the impurity in the fresh feed of impure methanol?
what is the wt% of serine in the stream that flow into the crystallizer filter unit?

Methanol is synthesized from carbon monoxide and hydrogen in a catalytic reactor.

The fresh feed to the process contains 32.0 mol% CO, 64 mol% H2 and 4 mol% n2. This stream is mixed with a recycle stream in a ratio of 10 mol recycle / 1 mol fresh feed to produce the feed to the reactor, which contains 14 mol% n2.

The reactor effluent goes to a condenser from which two streams emerge: a liquid product stream containing essentially all of the methanol formed in the reactor, and a gas stream containing all of the CO, H2, and n2 leaving the reactor.

The gas stream is split into two 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.

For a methanol production rate of 100 mol/h, calculate the fresh feed rate (mol/h), the molar flow rate and composition of the purge gas, and the overall and single-pass conversions.

Weekly leaderboard

Home
Homework Help 3,900,000
Chemistry 830,000
Start filling in the gaps now
Log in