Reactor Design 9
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The document discusses several types of chemical reactors, including recycle reactors, autocatalytic reactors, and considerations for optimizing reactor performance and operating conditions. It addresses recycle stream ratios, performance equations, temperature progression, and non-ideal flow concepts such as residence time distribution, states of aggregation, and mixing effects.
Reactor Design 9
- 1. Polymer/Chemical Reactor Design Muhammad Zafar Iqbal
- 2. Today Recycle Reactors and some important considerations Autocatalytic Reactors and their important considerations Optimum temperature Progression Reactor Operating Line Basics of Non-linear flow: Fundamental Concept
- 3. Recycle Reactors A reactor for which product stream is split and a part of that split stream is sent back to reactor to enhance the reactor performance is called a Recycle Reactor. Recycle Stream is defined as: Recycle stream is introduced to enhance the degree of mixing. Therefore it is conventionally said that for R=0, the behavior is totally plug and for R=very large, the behavior is mixed flow reactor.
- 4. Types of recycle reactor
- 6. Ref: Chemical Process design and Integration by Smith, Ch-13,14
- 7. Performance Equation For this plug flow reactor, the performance equation is given as:
- 8. The actual conversion at inlet is given by: The concentration at inlet to the reactor is given by So finally we get the following results: The final equation for any expansion factor value is: Also in terms of concentration,
- 10. Autocatalytic Reactors In general, when conc. Of reactants is high (at start) the rate of reaction is also high. When conc. Is lowered, the reaction proceeds slowly. In autocatalytic reactions, the rate of reaction at the start is slow but as the product is formed more and more, the speed of reaction increases up to a certain level then drops. Therefore there is always a need for optimization of reactors for autocatalytic reactions. A general representation of autocatalytic reaction is given as:
- 12. Mixed flow Vs Plug flow Reactor
- 13. Temperature and Pressure Effects in Single Reaction based Reactors There is a great influence of operating conditions on the reactor set up and optimization. Normally the following three step procedure is adopted: 1- T and P effects on equilibrium composition, rate of reaction and product distribution 2- The Heat effects and their impact on operating Temp. 3- Economic optimization of process Single Reactions: Two factors are considerable: 1- Conversion Level no product distribution 2- Reactor stability
- 15. Reactor Operating Line The size of a reactor for a given duty and for a given temperature progression is found from following procedure: Draw X A Vs T (Reactor Operating Line) Find Reaction rates at different X A along this path Plot 1/-r A Vs X A for this path Find the area under the curve or area of the rectangle depending upon the type of reactor used. Ref: Chemical Reaction Engineering by Levenspiel Chapter 9.
- 16. n
- 17. Non-Ideal Flow: Fundamental Concepts Three main factors which can describe the flow are: RTD State of Aggregation Earliness and Lateness of Mixing
- 19. States of Aggregation of the flowing stream
- 20. Mixing Ref: Chemical Reaction Engineering by Levenspiel Chapter 11.