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Instrumentation and control. Analytical Analysis in Chemical Process Control. Dr. –Ing. Naveed Ramzan. Department of Chemical Engineering, U.E.T. Lahore Pakistan. 10. August 2014 / Dr. –Ing Naveed Ramzan 1. Introduction.
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Instrumentation and control Analytical Analysis in Chemical Process Control Dr. –Ing. Naveed Ramzan Department of Chemical Engineering, U.E.T. Lahore Pakistan 10. August 2014 / Dr. –Ing Naveed Ramzan 1
Introduction • Purpose of Measuring Physical Properties - Control Product Quality - Maintain Safe Operation - Process Optimization
Outline Instruments for measurement of: • Composition • pH • Viscosity • Optical properties
Composition Measurement: Analyzers in the Process Industry • Purpose • Control of chemical processes • Requirements • Low Maintenance • Simplicity • “Ruggedness” • Few or no moving parts Reactor Control Environmental Monitoring Product Compositions
Challenges in Analyzer Design • Exposure to corrosive environments • Must withstand non-ideal concentrations of secondary components • Maintenance only once every few months • Reliability is key
Classification of Process Analyzers Analyzers Nonspecific (Inexpensive) Specific (Costly) Liquid Liquid Gas Gas Thermal Conductivity Electrical Conductivity Gas Chromatography IR/UV-VIS Spectroscopy
Sampling Systems Sample Conditioning Sample Extraction Analyzer Process Stream Sample Return
Sampling Systems • In-line sampling • Direct sampling in process line • Advantage: no sampling delay • Disadvantage: measurement affected by temperature and pressure variations • On-line sampling • Extract sample continuously and send to instrument • Advantage: control of temperature, pressure • Disadvantage: time lag before measurement
CHROMATOGRAPHY Chromatography basically involves the separation of mixtures due to differences in the distribution coefficient (equilibrium distribution) of sample components between 2 different phases. One of these phases is a mobile phase and the other is a stationary phase.
Distribution Coefficient (Equilibrium Distribution ) Definition: Different affinity of these 2 components to stationary phase causes the separation. Concentration of component A in stationary phase Concentration of component A in mobile phase
Kinds of Chromatography 1. Liquid Column Chromatography 2. Gas Liquid Chromatography 3. Thin-layer Chromatography
LIQUID COLUMN CHROMATOGRAPHY A sample mixture is passed through a column packed with solid particles which may or may not be coated with another liquid. With the proper solvents, packing conditions, some components in the sample will travel the column more slowly than others resulting in the desired separation.
FOUR BASIC LIQUID CHROMATOGRAPHY The 4 basic liquid chromatography modes are named according to the mechanism involved: 1. Liquid/Solid Chromatography (adsorption chromatography) A. Normal Phase LSC B. Reverse Phase LSC 2. Liquid/Liquid Chromatography (partition chromatography) A. Normal Phase LLC B. Reverse Phase LLC 3. Ion Exchange Chromatography 4. Gel Permeation Chromatography (exclusion chromatography)
??? Questions 10. August 2014 / Dr. –Ing Naveed Ramzan 21