Test _2 2008 Study Guide REVISED 3-18-08 v3

Test _2 2008 Study Guide REVISED 3-18-08 v3 - ChE 3015...

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1 ChE 3015 Study Guide for Test # 2 to be held Tuesday, 4/2/2008, from 7:00-8:30 PM in McBryde 113 REVISED 3/22/08 Test format Students should bring 1 page of notes (notes on the front and back are allowed) a calculator Test Topics This test will focus on material covered since Test #1. Students should be completely familiar with: assigned reading material and solutions to homework and example problems on sensors, transmitters, and control valves in “Fundamentals of Instrumentation and Process Control”, pp. 42-52; 60-130 assigned reading material and solutions to homework problems and all example problems in "Practical Process Control", Chapters 11-13. More details on test topics are given below: Practical Process Control, Chapters 11-13 - Unsteady state models and ordinary differential equations that arise from them 1. Modeling of open loop systems Derivation of the appropriate unsteady state (USS) balance equation - given a written or pictorial description of a system and specification of the process variable, derive the appropriate USS mass, mole, or energy balance. (Chapters 11-12 PPC) Mass/mole balance with multiple input and exit streams without reaction with reaction Energy balance with multiple input and exit streams without reaction with reaction 2. Nonlinear systems analysis - Using Taylors series expansions, linearize any nonlinear functions and nonconstant coefficient terms that appear in the USS balance equations. 3. Balance equation in “standard” form with deviation variables - With a balance equation that is now a linear ODE with constant coefficients, place the ODE in deviation variable form and write this in the “standard” form and derive the expressions for the time constant τ p and gain factor(s). If linearization had to be done, the time constant and gain factor(s) will be explicit functions of the steady state operating parameters, i.e. the time constant and gain factor(s) will vary as the design level of the process changes, just what we’ve seen in every Case Study in Control Station. 4. How much and how fast ? - Given expressions for the time constant and gain factor(s): a. Calculate the long-time limit of the change in the process variable given specified changes in the disturbance functions for the process. Δ PV = K p Δ (disturbance function) b. Estimate how long it will take for the process variable to get to within, say, 0.7% of its final, new SS value.
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2 Practice Problems: Sensors and transmitters Flow measurement 1. For a salt-water stream, specify at least 3 different flow measurement devices that are feasible. Discuss briefly some advantages and disadvantages of each. 2. For a liquid hydrocarbon stream, specify at least 2 different flow measurement devices that are feasible.
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This note was uploaded on 03/31/2008 for the course CHE 3015 taught by Professor Rmd during the Spring '08 term at Virginia Tech.

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Test _2 2008 Study Guide REVISED 3-18-08 v3 - ChE 3015...

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