Sample Questions in Chemical Engineering
Question 1.
INR 1700
  •                                         
                                            Hydrolysis of t-Butyl Chloride 
    • Need to prepare a Lab report.  
    • Format of Lab report is attached. (Page 4 onwards) 
    Learning Outcomes 
    1. To determine the order of the hydrolysis reaction of the reaction 
    2. To determine the effect of water: acetone ratio on the rate constant 
    Theory 
    The hydrolysis of t-butyl chloride takes place as follows: 
    (CH3)3CCl + H2O → (CH3)3COH + HCl 
    The progress of the hydrolysis is determined by making successive additions of 
    alkali and noting the time when the indicator changes colour to the acid state. 
    Since the alkali additions are small in relation to the large excess of water, 
    the system can be treated as pseudo first-order with respect to t-butyl chloride. 
    Safety 
    Wear safety glasses. Handle the glassware with care especially when inserting a 
    pipette into the safety bulb. The NaOH and t-BuCl are slightly corrosive so wash 
    any off immediately, a splash from any of the chemicals into your eye will be 
    painful. Wash your hands at the end of the lab. 
    Procedure 
    1. Prepare 50 cm3of a 90% water/10% acetone mixture. 
    2. Pour this into 125 cm3conical flask. 
    3. Fill a 50 cm3burette with 0.01M NaOH.’ 
    4. Add 2-3 drops phenolphthalein into the 125 cm3conical flask and shake content. 
    5. Discharge 2 cm3 NaOH from burette and shake content. 
    6. Pipette 1.0 cm3of the solution (of t-butyl chloride (1%) in acetone) provided, 
    into the conical flask and start the clock when the pipette is half empty. 
    7. Shake contents of conical flask and record the time for the indicator colour 
    ndicator colour change is observed). 
    9. Record the temperature of the content in the conical flask at this stage. 
    10. Repeat the whole experiment with two other water/acetone ratios - e.g. 80% 
    water and 20% Acetone.
    1 
    Treatment of Results 
    Consider the following questions during your experiment and include as part of 
    your writeup. 
    1. What are the units of first and second order rate constants? 
    2. What is meant by pseudo-first order reaction? Represent this in equations. 
    3. Derive an equation to show how the concentration of the reactant varies with 
    time for a first order, constant volume batch reaction. 
    4. How will you plot your data to determine the rate constant for the reaction? 
    5. How do you determine the slope of semi-logarithmic plot? 
    Confirm the order of the reaction and determine the reaction rate constant for 
    the different proportions of water in reaction mixture. 
    DATA 
    80% Water & 20% Acetone 
    (Volume of base added) 
    (time)
    3 
    2:23
    2 
    4:29
    1 
    7:53
    0.5 
    9:26
    0.5 
    13:32
    0.5 
    19:02
    0.5 
    25:36
    0.5 
    33:01
    
    
    
    90% Water & 10% Acetone 
    (Volume of base added) 
    (time)
    3 
    0:50
    2 
    2:15
    1 
    3:25
    0.5 
    4:12
    0.5 
    5:10
    0.5 
    6:33
    0.5 
    9:16
    0.5 
    11:40
    0.25 
    12:57
    0.3 
    15:18
    0.2 
    17:03
    0.5 
    25:02
    
    
    
    • Plot points as a trendline 
    • When becomes colourless note down the time 
    • Use error values
    2 
    • Calculate concentration and use log for calculations 
    • Include neutralization reactions 
    • For first case Ti = 22 and Tf = 24, Second Case Ti = Tf =23(values in oC).
    3 
    Format of Laboratory Reports 
    You only must write a short form of a lab report, from experimental results, discussion, and 
                                            
                                        
Question 2.
INR 3100
  •                                         
                                            THE UNIVERSITY OF HULL 
                                    Department of Chemical Engineering 
    Level 5 
    Process Control Assignment 
    Trimester 2 
    2021/22 
    500672 Process Control and Instrumentation for Chemical 
    Engineers 
    Page 1 of 11 
    Instructions: 
    You can work either individually or as a group of two on this assignment. 
    You are reminded of the University of Hull's policy on academic integrity, 
    which will be rigorously enforced. If in any doubt about the policy, please 
    onsult your Module Leader BEFORE you submit your assignment. In the event of 
    you needing to property data, please state your source of information. 
    DO NOT provide a handwritten work. Your final submission should be 
    typed in using, for example, MS word. You then need to convert this 
    document to PDF and upload it into Canvas. 
    . 
    If you work on this assignment as a group of two, 
    o One student should submit a full (single) PDF coursework 
    document in Canvas. Another should only submit the cover page 
    as part of his/her individual submission. o Write a short 
    paragraph to explain your individual contribution 
    (preferably, at the beginning of your submitted document). 
    Show clearly all your assumptions required to complete the 
    tasks of the assignment. Use a Harvard referencing system. 
    Page 2 of 11 
    Problem Description 
    The aim of this assignment is to design a closed loop control 
    system for a chemical process using analytical approach as well 
    as MATLAB/Simulink. You will be given two different processes 
    namely, () two liquid level tanks in series and (ii) two mixing 
    vessels in series (see Fig-1 and Fig-2 in Appindix-1). Each 
    group should choose one process only. If you work individually, 
    again, you should only choose one process from Appendix-1. 
    In this assignment you will be able to design your feedback 
    control system, create a P&ID and analyse its dynamic response. 
    You would also be able to design and tune your PID controller 
    and evaluate the stability of your control system using analytical 
    approach as well as MATLAB and Simulink. 
    Section A: P&ID for your selected closed loop control system 
    In this section you are required to carry out the following tasks; 
    For those who are selecting liquid level system (Fig-1): 
    Task-A1: 
    It is required to control the outlet flow rate Q3 in the second 
    ank by regulating the inlet flow rate Q1. Add all components 
    required and develop a line diagram for a closed loop liquid level 
    control. 
    Task-A2: Draw a P&ID of the liquid level control system. 
    [lt's recommended to use MS Visio. However, you may use any other 
    software, e.g. MS PowerPoint, MS word, etc.). 
    For those who are selecting mixing system (Fig-2): 
    Task-A1: It is required to control the outlet concentration, 
    X3, of component A by regulating the concentration Xı of the 
    inlet feed. Add all components required and develop a line diagram 
    for a feedback composition/concentration control system. 
    Page 3 of 11 
    Task-A2: Draw a full P&ID of the concentration control system. 
    [It's recommended to use MS Visio. However, you may use any other 
    software, e.g. MS PowerPoint, MS word, etc.). 
    Section B: Transfer Function and Response of a Process to Step input 
    In this section you are required to carry out the following tasks; 
    For those who are selecting liquid level system (Fig-1): 
    The model for a first liquid level tank (shown in Fig-1) is 
    given by the following ODE; 
    A1 = 91 - 92 
    and; 
    92 = na 
    where A is the area of the first tank, hy is the liquid height of 
    the first tank, 41 and 92 are the inlet and outlet volumetric 
    flow rate for the first tank respectively and R is the resistance 
    coefficient of valve-1. The above two equations can also be 
    duplicated for the second tank using appropriate symbols/notations.
     [ You need to assume the reasonable values for all required variables, 
     e.g. tank areas, valve resistance, etc.) 
    Task-B1: Assuming zero initial conditions, Use Laplace transform to 
    create the transfer function that describes the relationship between 
    the height H(s) and the flow rate Q.(s) for the first tank (i.e. 1:69). 
    Task-B2: 
    Assuming zero initial conditions, Use Laplace transform to create the 
    transfer function that describes the relationship between the height Hz(s) 
    and the flow rate Qz(s) for the second tank (i.e. 43). 
    4S 
    Page 4 of 11 
    Task-B3: 
    Assuming zero initial conditions, Use Laplace transform to create the transfer 
    function that describes the relationship between the outlet flow rate of the 
    second tank Q3(s) and the inlet flow rate Q_(s) of the first tank (i.e. 23 (8). 
    18 
    Task-B4: 
    Use MATLAB or Simulink to analyse your selected process when subjected 
    to a step input. You may consider the following open loop system. Assume a 
    value for M. 
    02(5) 
    Q3(s) 
    T 
    &($) 
    Gpi 
    Gp2 
    where Gp is the transfer function of the first tank (i.e. Gpu = 22(3) 
    and Gpz is the transfer function of the second tank (i.e. Gp2 = 3(3). 
    Provide a brief discussion to explain the response obtained from MATLAB or Simulink. 
    Is the process show oscillation? Why/why not? If the response shows oscillation,
    calculate the dynamic performance parameters (rise time, peak time, 2% settling 
    time and the percentage of overshoot). Compare the values of the dynamic performance 
    parameters obtained from calculation with those obtained from MATLAB. 
    [Note: if your response does not show any oscillation, you don't need to 
    calculate the dynamic performance parameters). 
    For those who are selecting mixing system (Fig-2): 
    The model for a first mixer system (shown in Fig-2) is given by the following 
    ODE; 
    dxz(t) V1 = 9(x1 - x2) 
    where Vis the volume of the first mixing vessel, X1 is the concentration at the 
    feed, X2 is the concentration of component A at the outlet of the first mixing 
    vessel and q is the volumetric flow rate. The above two equations can also be 
    duplicated for the second mixing vessel using appropriate symbols/notations. 
    [ You need to assume the reasonable values for all required variables, e.g. 
    volumes, flow rate, etc.] 
    Page 5 of 11 
    Task-B1: Use Laplace transform to create the transfer function that describes 
    the relationship 
    tlet concentration X,(s) and the inlet concentration X, (s) for the first mixing 
    vessel (i.e. 23 ). [Note: The initial condition (i.e. the concentrations at 
    steady state) is; x3(0) = x2(0) = x1(0) = 1 kg mol/m3). 
    Task-B2: Use Laplace transform to create the transfer function that describes 
    the relationship between the two concentrations X (s) and X3(s) for the second 
    mixing vessel (i.e. 
    303). [Note: The initial condition is; x3(0) = x2(0) = x1(0) = 1 kg mol/m3). 
    Task-B3: 
    Use Laplace transform to create the transfer function that describes 
    the relationship between the outlet concentration of the second tank X 
    (S) and the inlet concentration X1(s) of the first mixing vessel (i.e. 138).
     Note: The initial condition is; x3(0) = x2(0) = x1(0) = 1 kg mol/m3). 
    Task-B4: Use MATLAB or Simulink to analyse your selected process when 
    subjected to a step input. You may consider the following open loop system. 
    X2(s) 
    x (s) 
    7x3(s) 
    Gpi 
    Gp2 
    where Gp is the transfer function of the first mixing vessel (i.e. Gp1 = 33) 
    and Gpz is the transfer function of the second mixing vessel (i.e. Gp2 = 13(3)
    . Assume a value for M. 
    Provide a brief discussion to explain the response obtained from MATLAB or
     Simulink. Is the process show oscillation? Why/why not? If the response
      shows oscillation, calculate the dynamic performance parameters (rise time,
       peak time, 2% settling time and the percentage of overshoot). Compare the
        values of the dynamic performance parameters obtained from calculation with
         those obtained from MATLAB. (Note: if your response does not show any 
         oscillation, you don't need to calculate the dynamic performance parameters). 
    Page 6 of 11 
    Section C: Closed Loop Control System 
    In this section you are required to carry out the following tasks; 
    Task-C1: Develop your closed loop control system using the process transfer 
    function obtained in section B. For those who selected a liquid level system, 
    define your process transfer 
    function G,(s) as 31. and for those who selected a mixing system, define the process 
    X (S) 
    transfer function Gp(s) as 3. You need to assume appropriate transfer functions 
    for the valve and the transmitter in your closed loop control system. 
    Assume the controller is proportional controller with a gain Kc. 
    Task-C2: 
    Derive the overall transfer function of the closed loop control 
    system obtained in Task 
    C1. 
    Section D: Stability of a feedback control system 
    In this section you are required to carry out the following tasks; 
    Task-D1: Consider the closed loop control system obtained in Task-C1. 
    Analyse the stability of the system by finding the range of K, 
    that makes the system stable. You can use either a Routh test or 
    direct substitution method. 
    Task-D2: Design your closed loop control system in Simulink and analyse
     its stability. You should discuss, at least, the response of the system
    at three different values of Kc (i.e. one value within the Ke range 
    obtained in Task-D1, one value outside the range and one value at the
    upper limit of the K, range). Provide a clear discussion to explain the
     system response at these three cases. 
    Page 7 of 11 
    Section E: PID Controller Design 
    In this section you are required to carry out the following tasks; 
    Task-E1: The proportional controller in Task-C1 is now replaced by a PID 
    controller. Use a closed loop Z&N method to tune the PID controller by 
    finding all required controller 
    gains. 
    Task-E2: Use the values of PID controller settings obtained from 
    Ziegler-Nichols (Z&N) tuning method in Task-E1 and your Simulink model 
    to analyse the response of your control system to a step input using 
    P-only controller, Pl and PID respectively. Provide a brief explanation
     of the advantages of integral and derivative modes in PID controller. 
     [Note: you might need to modify the values obtained from Z&N tuning method 
     to get optimum controller gains that can approximately achieve a quarter 
     decay ratio response). Define all your assumptions. 
    Page 8 of 11 
    Appendix-1 1) Two liquid level tanks in series 
    4.(t): inlet volumetric flow rate into tank-1 4.(t): outlet volumetric 
    flow rate from tank-1 43(t): outlet volumetric flow rate from tank-2 hi(t): 
    height in tank-1 hy(t): height in tank-2 R1 and Rz: resistance of valves V-1 and V-2 
    Assumptions: 
    Fluid density is constant The tank is cylindrical 
    Tank-1 
    Tank-2 
    V-2 Fig.1: Two liquid level tanks in series 
    Model of Tank-1: 
    dh(t) 
    41 dt 
    = 91(t) - 92(t) 
    and; 
    9z(t) = RM (1) 
    Model of Tank-2: 
    A, dhz(t) = qz(t) – 93(t) 
    and; 
    93(t) = R 12(e) 
    Notes; 
    • You should assume your own (but reasonable) values for all variables (e.g. Aj, 
    A2, R1, R2 etc.) required to complete the tasks of the assignment. You may need 
    to conduct a quick search in literature to scale all variables correctly. 
    • The block diagram of the process is shown below. 
    Gpi(s): Transfer function of tank-1 Gw(s): Transfer function of tank-2 
    Page 9 of 11 
    2. Two mixing vessels in series 
    (t): volumetric flow rate (m/min) V, and V. : volume of vessels 1 and 2 
    (m) xi(t): reactant concentration of nominal feed (kg mol/m) xz(t): concentration 
    of component A at the outlet of Vessel-1 (kg mol/m) Xz(t): concentration of component A
     at the outlet of Vessel-2 (kg mol/mo) 
    Xi=1 kg mol/m 
    Assumptions: - The system is initially at steady state. - The feed concentration, 
    X, is 1 kg mol/m - all concentrations, at steady state, are equal x, - Therefore, 
    X3 (0) = x2(0) = x1(0) = 1 kg mol/m3 
    - 
    - 
    - 
    - 
    - 
    - 
    - 
    - 
    - 
    - 
    - 
    - 
    - 
    - 
    - 
    Mixing vessel-1 
    Mixing vessel-2 Fig.2: Two mixing vessels in series 
    Model for mixing vessel-1: 
    dxz(t) _ 
    Vi 
    =9(x1 - x2) 
    Model for mixing vessel-2: 
    vedxz(t) = (x2 – x3) 
    Notes; 
    • You should assume your own (but reasonable) values for all variables (e.g. V, 
    V2, q etc.) required to complete the tasks of the assignment. You may need to 
    conduct a quick search in literature to scale all variables correctly. 
    • The block diagram of the process is shown below. 
    X2(s) 
    Gp(s): Transfer function of mixing vessel-1 Gpz(S): Transfer function of mixing 
    vessel-2 
    X1(S) 
    X3(s) 
    Gp1 
    Gp2 
    << End of Assignment >> 
    Page 10 of 11 
    Marking criteria 
    The marking criteria shown below describes the required criteria to achieve 
    maximal marks for individual task. 
    Task 
    Marking criteria to achieve maximum mark 
    Maximal achievable 
    mark 
    10 
    Ho 
    42(S) 
    Develop a complete line diagram by showing and defining all (A)(1) required 
    components in the closed loop control system. (A)(2) Construct a full P&ID 
    of your selected feedback control loop. 
    Define all symbols and labels used. (B)(1) Use the given data to derive 
    the transfer function 107 of the 
    process. Show all steps of your calculation. Use the given data to derive 
    the transfer function 25 of the process. Show all steps of your calculation.
     Use the given data to derive the transfer function 369 of the 
    Qı(S) process. Show all steps of your calculation. 
    Analyse the response of your control system to a step input. (B)(4) comment
     on the response obtained and give a clear 
    explanation on why there is/there is no' oscillation in the response. In case
     of oscillation, calculate the dynamic performance criteria (tp, tr, ts 
     and %OS). You should also compare these values with those obtained from 
     MATLAB/Simulink. 
    Design your closed loop control system. You need to show (C)(1) reasonable
     assumptions to define the transfer functions of the 
    control valve and the transmitter. If you select these transfer 
    functions from literature, you must provide a proper referencing 
    (i.e. Harvard style). 
    Derive the overall transfer function of your complete feedback (C)
    (2) control system. Show all steps of calculation. 
    Analyse the stability of the feedback system and find the range of the 
    controller gain that makes the system stable. Use 
    either Routh test or direct substitution methods. Show all (D)(1) steps.
     (D)(2) Design your closed loop control system in Simulink and 
    analyse/discuss the stability of your Simulink model using 
    different values of proportional gain obtained in D(1). (E)(1) Use Z&N 
    tuning method to tune your PID controller. Show all 
    steps of your calculation. (E) (2) Use the values of PID controller 
    settings obtained from 
    Ziegler-Nichols tuning method and your Simulink model to analyse the 
    response of the outlet temperature of the heat exchanger to a unit step 
    input using P-only controller, Pl and PID. Explain the advantages of 
    integral and derivative modes in PID controller. Modify these the 
    controller gains manually to get a response close to 44 decay ratio. 
    Page 11 of 11 
    
                                        
Question 3.
INR 2000
  •                                         
                                            Heat Transfer 
    You need to submit softcopy (PDF) of your detailed report. 
    Follow the following guidelines for completion of the project. 
    The report should include: 
    1. Assumptions if any, 
    2. All input data, calculations should be performed in detail. 
    3. All charts and tables with captions used in calculations should be included. 
    4. You can use Excel or MATLAB and provide their results as figures with captions in report 
    5. Code/calculation table/supporting files should be attached as Appendix. 
    6. You need to research in the reference book proposed in the syllabus to get 
    information/ data, include their reference at end of your report. 
    Problem Statement: Design a double-pipe Heat Exchanger 
    An organic liquid at 175 °F is to be cooled with water that is available at 70°F. 
    A double-pipe heat exchanger consisting of six hairpins connected in series will be 
    used. Each hairpin is 16 ft long and is made with 2- and 1-in. stainless steel (k = 9.2 Btu/h.ft°F) 
    pipes. Flow rates and fluid properties, which may be assumed constant, are given below. 
    The organic liquid will flow through the inner pipe, and its heat-transfer coefficient has 
    been determined: hi =250 Btu/h.ft. °F. The streams will flow counter-currently through the 
    exchanger. 
    Property Organic Liquid Water 
    m(mass flow rate)lb/hr 11765 7000 
    Cp(Btu/lbm. °F) 0.51 1 
    K(Btu/h.ft. °F) 0.38 
    Μ(cp) 0.65 
    Pr 4.14 
    1. Calculate the heat-transfer coefficient, ho, for the water. 
    2. Calculate the clean overall heat-transfer coefficient. 
    3. Determine the outlet temperatures of the two streams that will be achieved when the heat 
    exchanger is first placed in service. 
    4. Calculate the average wall temperature of the inner pipe when the heat exchanger is clean.
    
                                        
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