A two-unit separation is used to dewater ethanol. First, a 320 mol/hr feed(Stream 1) of a mixture of 0.750 mole fraction ethanol (E) and 0.250 molefraction water (W) is fed to a distillation column. The extractive agent, benzene(B), is added to the distillation column in a mixture of 0.940 mole fractionbenzene and 0.060 mole fraction water (Stream2). This mixture consists offresh benzene (Stream 3) and the recycle stream of benzene and waterrecovered from the separator (Stream 4). The company wishes to produce a0.98 mole fraction ethanol (0.02 mole fraction benzene) product stream fromthe overhead of the distillation column (Stream 5). The bottoms product(Stream 6), containing just benzene and water, is sent to the separator. Thecomposition of the benzene/water mixture leaving the bottom of the separator(Stream 7) is 0.86 mole fraction benzene and the balance water. Some of thebottom stream leaving the separator is recycled (Stream 4) and added to thefresh benzene feed to the column and the rest of the bottom stream (57 mol/hr)is sent to another unit (Stream 8). The stream leaving the top of the separator(Stream 9) is pure water.a) Why is a recycle stream (Stream 4) included in this process?b) What is the molar flowrate of the ethanol product (Stream 5)?c) What is the molar flowrate of water removed in the separator (Stream 9)?d) What is the molar flowrate of fresh benzene (Stream 3)?e) What are the molar flowrate and mole fractions of the distillation column bottoms stream 6 ### Diagram DescriptionThis diagram illustrates a process flow involving a distillation column and a separator. Below is a step-by-step explanation of the streams and components:1. **Distillation Column** - **Stream 1:** The input to the distillation column. This stream represents the feed entering the column for separation. - **Streams 2 and 3:** Additional inputs that merge and feed into the distillation column along with Stream 1. - **Stream 4:** An output stream from the distillation column, typically representing the bottom product. - **Stream 5:** Another output from the distillation column, usually representing the overhead product.2. **Separator** - **Stream 6:** The output from the distillation column which enters into the separator for further processing. - **Stream 7:** A downward output from the separator, indicating one of the separated components. - **Stream 8:** The continuation of Stream 7, showing the flow of the component after separation. - **Stream 9:** An additional separated output, typically a gaseous or lighter product from the separator.### ExplanationIn this setup:- The **distillation column** is used as the primary separation unit where different components of the feed (Streams 1, 2, and 3) are initially separated into Streams 4 and 5.- The **separator** then receives Stream 6 from the distillation column to further refine the separation process, resulting in Streams 7, 8, and 9. This process is commonly used in chemical engineering for separating mixtures into their individual components based on differences in volatility or other properties.

Given, The feed rate of stream-1, n1 = 320 mol/hr The composition of stream-1 is The mole fraction…

A two-unit separation is used to dewater ethanol. First, a 320 mol/hr feed (Stream 1) of a mixture of 0.750 mole fraction ethanol (E) and 0.250 mole fraction water (W) is fed to a distillation column. The extractive agent, benzene (B), is added to the distillation column in a mixture of 0.940 mole fraction benzene and 0.060 mole fraction water (Stream2). This mixture consists of fresh benzene (Stream 3) and the recycle stream of benzene and water recovered from the separator (Stream 4). The company wishes to produce a 0.98 mole fraction ethanol (0.02 mole fraction benzene) product stream from the overhead of the distillation column (Stream 5). The bottoms product (Stream 6), containing just benzene and water, is sent to the separator. The composition of the benzene/water mixture leaving the bottom of the separator (Stream 7) is 0.86 mole fraction benzene and the balance water. Some of the bottom stream leaving the separator is recycled (Stream 4) and added to the fresh benzene feed to the column and the rest of the bottom stream (57 mol/hr) is sent to another unit (Stream 8). The stream leaving the top of the separator (Stream 9) is pure water. a) Why is a recycle stream (Stream 4) included in this process? b) What is the molar flowrate of the ethanol product (Stream 5)? c) What is the molar flowrate of water removed in the separator (Stream 9)? d) What is the molar flowrate of fresh benzene (Stream 3)? e) What are the molar flowrate and mole fractions of the distillation column bottoms stream 6

Introduction to Chemical Engineering Thermodynamics

8th Edition

ISBN:9781259696527

Author:J.M. Smith Termodinamica en ingenieria quimica, Hendrick C Van Ness, Michael Abbott, Mark Swihart

Publisher:J.M. Smith Termodinamica en ingenieria quimica, Hendrick C Van Ness, Michael Abbott, Mark Swihart

Chapter1: Introduction

Section: Chapter Questions

Problem 1.1P

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A two-unit separation is used to dewater ethanol. First, a 320 mol/hr feed
(Stream 1) of a mixture of 0.750 mole fraction ethanol (E) and 0.250 mole
fraction water (W) is fed to a distillation column. The extractive agent, benzene
(B), is added to the distillation column in a mixture of 0.940 mole fraction
benzene and 0.060 mole fraction water (Stream2). This mixture consists of
fresh benzene (Stream 3) and the recycle stream of benzene and water
recovered from the separator (Stream 4). The company wishes to produce a
0.98 mole fraction ethanol (0.02 mole fraction benzene) product stream from
the overhead of the distillation column (Stream 5). The bottoms product
(Stream 6), containing just benzene and water, is sent to the separator. The
composition of the benzene/water mixture leaving the bottom of the separator
(Stream 7) is 0.86 mole fraction benzene and the balance water. Some of the
bottom stream leaving the separator is recycled (Stream 4) and added to the
fresh benzene feed to the column and the rest of the bottom stream (57 mol/hr)
is sent to another unit (Stream 8). The stream leaving the top of the separator
(Stream 9) is pure water.
a) Why is a recycle stream (Stream 4) included in this process?
b) What is the molar flowrate of the ethanol product (Stream 5)?
c) What is the molar flowrate of water removed in the separator (Stream 9)?
d) What is the molar flowrate of fresh benzene (Stream 3)?
e) What are the molar flowrate and mole fractions of the distillation column bottoms stream 6

### Diagram Description

This diagram illustrates a process flow involving a distillation column and a separator. Below is a step-by-step explanation of the streams and components:

1. **Distillation Column**
- **Stream 1:** The input to the distillation column. This stream represents the feed entering the column for separation.
- **Streams 2 and 3:** Additional inputs that merge and feed into the distillation column along with Stream 1.
- **Stream 4:** An output stream from the distillation column, typically representing the bottom product.
- **Stream 5:** Another output from the distillation column, usually representing the overhead product.

2. **Separator**
- **Stream 6:** The output from the distillation column which enters into the separator for further processing.
- **Stream 7:** A downward output from the separator, indicating one of the separated components.
- **Stream 8:** The continuation of Stream 7, showing the flow of the component after separation.
- **Stream 9:** An additional separated output, typically a gaseous or lighter product from the separator.

### Explanation

In this setup:

- The **distillation column** is used as the primary separation unit where different components of the feed (Streams 1, 2, and 3) are initially separated into Streams 4 and 5.
- The **separator** then receives Stream 6 from the distillation column to further refine the separation process, resulting in Streams 7, 8, and 9.

This process is commonly used in chemical engineering for separating mixtures into their individual components based on differences in volatility or other properties.

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