Material Balances

Question 1

What is a Batch Process

Answer 1

No Mass Crosses System Boundary

Unsteady State

Process Variables change with time

Question 2

What is a Continous Process

Answer 2

Mass Crosses System Boundary Continuously

Steady State

Process Variables dont change with time

Question 3

What is a Semi-Batch Process

Answer 3

Mass Crosses the System Boundary Periodically

Transient State

Process Variables change at a slower rate than a steady state

Question 4

What is the “Golden Equation”

Explain how this equation is Applied to a Continous Process

Answer 4

Input + Generation - Output - Consumption = Accumulation

In a Continous Process, Accumulation is always zero

Question 5

Molar Flow Rate of Component i in a Mixture =

Mass low Rate of Component i in a Mixture =

Answer 5

Molar Fraction * Total Molar FLow Rate

Mass Fraction * Total Mass Flow Rate

Question 6

Draw the Flow Diagram

Answer 6

Question 7

What Changes when a stream enters a Unit Rectangle (Reactor, separator) in a flow Diagram?

Answer 7

Molar Composition (Mole Fractions of Components)

Mass Composition (Mass Fraction of Components)

steams connected with no Unit Rectangle in between have the same composition

Question 8

What is the Purpose to the Purge Stream

Answer 8

Prevents Accumulation within the system due to Impurities entering through the Fresh Feed.

Alternative to Separating Impurities from the Recycle Stream
- Seperation can be difficult/ Expensive
- However Impurities must still exist the system to keep the Process Continuous

Question 9

1

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Question 10

2

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Question 11

Work out all of the Stochiometric Ratios for the Following Equation

Answer 11

Question 12

2 Reactions are occurring in a process

A Main Reaction and a Side Reaction

In Yield, Conversion & Selectivity are both considered?

Answer 12

Conversion is Pathway insensitive, meaning both main and side reactions must be considered

Yield = Actual Product Formed/ Theoretical Product Formed

To Calculate the Theoretical Product formed
Consider :
No Side Reactions
Limiting Reactant Reacts Completely
100% Reactor Conversion

Selectivity = Mol of Desired Product/ Mol of Undesired Product
- pathway insensitive

Question 13

What are the Formulas for Conversion , Yield and Selectivity

Answer 13

Question 14

What is the Purpose for a Recycle Stream

What is Recycle Ratio

Answer 14

Recovery of Unconsumed Reactants and Catalysts, which is fed back into the reactor inlet to be reused

Recycle Ratio:
Flow Rate of Recycle/ Flow rate of Fresh Feed

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Question 28

What does On Molar Basis Mean

Answer 28

Flow rate compared to the flow rate of the reactor outlet

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Question 37

What happens to the recycle ratio if single pass conversion decreases?

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