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CRE Reactor Design Project. Team #2: Kyle Lynch David Teicher Shu Xu. The Partial Oxidation of Propylene to Generate Acrolein. Overview. Project Objective Process Background Material Balance Simple Kinetics and Rate Expressions Pressure Drop and Reactor Configuration Multiple Reactions

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cre reactor design project

CRE Reactor Design Project

Team #2:

Kyle Lynch

David Teicher

Shu Xu

The Partial Oxidation of Propylene to Generate Acrolein

overview
Overview
  • Project Objective
  • Process Background
  • Material Balance
  • Simple Kinetics and Rate Expressions
  • Pressure Drop and Reactor Configuration
  • Multiple Reactions
  • Energy Balance
  • Optimization and Conclusions
project objectives
Project Objectives
  • Design a Fixed Bed Reactor (FBR) for the production of acrolein by the partial oxidation of propylene
  • Produce 75,000 metric tons acrolein per year
  • Optimize the reactor design to minimize cost
project objectives1
Project Objectives
  • Literature Review
    • Research information on raw materials and products
    • Investigate catalysts and reaction kinetics
  • Reactor Design
    • Develop mole balances for multiple reactions
    • Implement pressure drop & energy balance equations
    • Optimize reactor
background information
Background Information
  • Acrolein
    • Raw material used for the production of pyridine,

β-picoline, and some essential amino acids1

    • Used for cleaning irrigation ditches, and other derivatives can be made into rubbers, glues, and polymers2
    • Anti-microbial behavior
      • Biocide in oil well to suppress the growth of bacteria2
    • 100-500 million pounds produced in the U.S. in 20022

CH2=CH-CHO

current industry processes and conditions
Current Industry Processes and Conditions
  • Industry produces acrolein by the partial oxidation of propylene using oxygen and steam
  • The reaction is carried out in a catalytic FBR ranging between 350-450 °C1
  • Gaseous products leave and are quenched by cold water, then enter absorption column for product recovery3

CH2=CH-CH3 + O2 CH2=CH-CHO + H2O

design development
Design Development
  • Design 1-Preliminary mass and energy balance
  • Design 2-Reactor volume using simple reaction rate expression
  • Design 3-Pressure drop and reactor configuration
  • Design 4-Multiple reactions
  • Design 5-Energy balance on multiple reactions
  • Final Design-Optimization
design 1 assumptions
Design 1 Assumptions
  • A total of two weeks each year are allotted for scheduled shutdowns
  • All reactants and products are vapors
  • Air is used as an oxygen source
  • A 1:11 ratio of propylene:oxygen is outside the flammability limits4
  • The inlet pressure is 1 atm5
  • Negligible kinetic and potential energy losses
  • Isothermal, T=623.15 K5
design 1 material balance
Design 1: Material Balance
  • Material balance for annual production rate of 75,000 metric tons

CH2=CH-CH3 + O2 CH2=CH-CHO + H2O

*Design specification for acrolein production rate is 0.04412 kmol/s

design 2 assumptions
Design 2 Assumptions
  • All Design 1 assumptions
  • A conversion of 0.85 will be achieved3
  • 1000 kg/m3 is Catalyst bulk density6
  • Reactor is at steady state
  • Ideal gas law applies
  • Simple kinetics6
design 2 reactor volume with simple kinetics
Design 2: Reactor Volume with Simple Kinetics
  • To simulate the FBR being designed, a Polymath® model was developed.
  • The Polymath® reactor was created as a function of catalyst weight
  • Aspen Plus® used to examine the relationships between temperature, reactor volume, and conversion
design 2 reactor volume and simple kinetics
Design 2: Reactor Volume and Simple Kinetics
  • Developed an isothermal reactor model as function of catalyst weight using Polymath® and ASPEN ®

* Higher temperatures require smaller reactors for same conversion

V= 167,000 m3

design 3 assumptions
Design 3 Assumptions
  • All Design 2 assumptions – Inlet pressure is 3 atm6
  • Catalyst void fraction of 0.46
  • Particle diameter of 5 mm7
  • Inlet viscosity is that of pure steam4
  • Schedule 40 pipe used for multi-tube reactors8
design 3 isothermal reactor with pressure drop
Design 3: Isothermal Reactor with Pressure Drop
  • Implemented Ergun pressure drop equation into design
  • Optimized reactor so pressure drop is less than 10%
conversion with and without 10 pressure drop
Conversion with and without 10% Pressure Drop

* Pressure drop decreases conversion

reaction network
Reaction Network
  • Reactions are carried out in a catalytic FBR with temperatures ranging between 350-390°C
  • Acrolein is desired product
  • Major by-products9
    • Water
    • CO and CO2
    • Acetadehyde

C3H6+ O2 C2H4O + H2O

design 4 assumptions
Design 4 Assumptions
  • All Design 3 assumptions – 2830 kg/m3 is catalyst particle density10
  • Tan et al. reaction kinetics representative9
  • CO2 reaction rate independent of temperature
design 4 multiple reactions reactor
Design 4: Multiple Reactions Reactor
  • Modified the reactor to include multiple reactions
  • Used approved reaction kinetics to calculate species flow rates

V= 287.5 m3

design 5 assumptions
Design 5 Assumptions
  • All Design 4 assumptions
  • 227 W/m2-K is heat transfer coefficient6
  • Heat capacities are constant
  • Heats of reactions are constant
  • Coolant temperature is constant at 618.15 K6
design 5 non isothermal reactor with energy balances
Design 5: Non-Isothermal Reactor with Energy Balances

An energy balance across the reactor was introduced to further validate the model as a suitable representation of the actual reactor

design 5 non isothermal reactor with energy balance
Design 5: Non-Isothermal Reactor with Energy Balance
  • Incorporated energy balance into reactor design
  • Compared isothermal reactor and reactor with constant coolant temperature

The Effect of Coolant Temperature on Temperature Profile

*Coolant temperature effects severity of hotspot

V= 281.3 m3

reactor gain
Reactor Gain
  • “Gain” measures the dynamic stability of the reactor
  • A “Gain”< 2 is desired
final design assumptions
Final Design Assumptions
  • The catalyst void fraction is 0.46
  • Catalyst bulk density is 1698 kg/m3 for α-Bi2Mo3O1210
  • The inlet pressure is 3 atm6
  • The inlet temperature is 663.15 K9
  • The coolant temperature is constant at 658.15 K6
references
References
  • 1John J. McKetta. “Acrolein and Derivatives” Encyclopedia of Chemical Processing and Design.
  • 2Toxicological Profile for Acrolein, U.S. Department of Health and Human Service, Agency for Toxic Substance and Disease Registry (August 2007).
  • 3“Acrylic Acid and Derivatives.” Kirk-Othmer Encyclopedia of Chemical Technology. 4th Edition.
  • 4Chemical Database Property Constants. DIPPR Database [Online]. Available from Rowan Hall 3rd Floor Computer Lab. (Accessed on 1/26/08).
  • 5L. D. Krenzke and G. W. Keulks, The Catalytic Oxidation of Propylene: VIII. An Investigation of the Kinetics over Bi2Mo3O12,Bi2MoO6, and Bi3FeMo2O12. The Journal of Catalysis Volume 64 (1980) p. 295-302.
  • 6Dr. Concetta LaMarca
  • 7“Reaction Technology.” Kirk-Othmer Encyclopedia of Chemical Technology. 4th Edition.
  • 8Perry, Robert. Perry's Chemical Engineers' Handbook. 7th. New York: McGraw-Hill, 1997.
  • 9H.S. Tan, J. Downie, and D.W. Bacon, The Reaction Network for the Oxidation of Propylene Over a Bismuth Molybdate Catalyst, The Canadian Journal of Chemical Engineering Volume 67 (1989) p. 412-417.
  • 10Cerac Incorporated. “MSDS Search” 25 March 1994. Accessed: 8 April 2008. <http://asp.cerac.com/CatalogNet/default.aspx?p=msdsFile&msds=m000443.htm>