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engineering
chemical engineering
Questions and Answers of
Chemical Engineering
For Exercise 20.1, suppose that a constraint is placed on the manipulated variable, uk+j ≤ 0.2 for j = 1, 2,.., M – 1. Let ∆t = 2 and N = 40. Select values of M, P, and R so that these
For Exercise 20.1, consider two sets of design parameters and simulate unit step changes in both the disturbance and the set point. Assume that the disturbance model is identical to the process
Consider the unconstrained, SISO version of MPC in Eq. 20-57. Suppose that the controller is designed so that the control horizon is M = 1 and the weighting matrices are Q = I and R = 1. The
A theoretical advantage of MPC for ideal conditions is that it guarantees that both controlled and manipulated variables satisfy specified inequality constraints. Briefly discuss why this theoretical
In Section 20.6.1, MPC was applied to the Wood-Berry distillation column model. A MATLAB program for this example and constrained MPC are shown in Table E20.9.The design parameters have the base case
Design a model predictive controller for the process,Select a value of N based on 95% completion of the step response and ?t = 2. Simulate the closed1oop response for a set-point change using the
Repeat Exercise 20.9 for the situation where the input constraints have been changed to -0.3 and+0.3.
A standard signal range for electronic instrumentation is 4—20 mA. For purposes of monitoring instruments using limit checks, would it be preferable to have an instrument range of 0—20 mA?
An analyzer measures the pH of a process stream every 15 minutes. During normal process operation, the mean and standard deviation for the pH measurement are x = 5.75 and s = 0.05, respectively. When
In a computer control system, the high and low warning limits for a critical temperature measurement are set at the “2-sigma limits,” T’ ± 2σT. Where T is the nominal temperature and
Develop a CUSUM chart for the thickness data of Example 21.2 using K = 0 and H = 4. How many chart violations occur? Repeat for an EWMA chart and a values of λ = 0.25.
In a manufacturing process, the impurity level of the product is measured on a daily basis. When the process is operating normally, the impurity level is approximately normally distributed with a
A drought in southern California resulted in water rationing and extensive discussion of alternative water supplies. Some people believed that this drought was the worst one ever experienced in Santa
Develop CUSUM and EWMA charts for the rainfall data of Exercise 21.6 considering the data for 1900 to 1930 to be the “normal operating data.” Use the following design parameters: K = 0.5, H = 5,
An SPC chart is to be designed for a key process variable, a chemical composition, which is also a controlled variable. Because the measurements axe very noisy, they must be filtered before being
For the BOD data of Example 21.5, develop CUSUM and EWMA charts. Do these charts indicate an “abnormal situation”? Justify your answer.
Calculate the average values of the Cp and Cpk capability indices for the BOD data of Example 21.5, assuming that LSL = 5 mg/L and USL = 35 mg/L. Do these values of the indices indicate that the
Repeat Exercise 21.10 for the solids data of Example 21.5, assuming that USL = 1600 mg/L and LSL = 1200 mg/L.
Consider the wastewater treatment problem of Examples 21.5 and 21.6 and live new pairs of measurements shown below. Calculate the value of Hotelling?s T2 statistic for each pair using the information
Consider the microwave oven as an example of a discrete state process. The process variables that can be on or off include fan, light, timer, rotating base, microwave generator, and door switch. The
A pump motor operates by a push button that once actuated, keeps the pump on until the operator pushes a stop button. Also there is an emergency stop if the pump overheats (T> TH). Draw a logic
A truth table for a set of inputs is shown below where A and B are inputs and Y is an output.Construct binary operations (AND, OR, NOT) in series or parallel that yield Y front A and B.
A batch operation is used to heat a Liquid to a specified temperature. There is a start button, a stop button, inlet/outlet valves, and limit sensors for low tank level (LL) and high tank level (LH).
Consider a process that consists of a liquid chemical tank with two level indicators, a heater inlet and outlet pumps, and two valves. Assume that we want to perform the following sequence of
A two-tank filling system is shown in figure. E. Both tanks are used in a similar way. Tank 1 is empty when the level is less than L1 and is full when the level is greater than L2. Initially, both
Consider a neutralization system shown in figure, where a certain amount of acid feed is added to a tank, chemically treated, and then sent to the next tank. Sensor pHS indicates whether or not the
Consider the tank car unloading of a hazardous chemical, as shown in Fig. A pump is used to empty the tank car and fill the storage tank. Then the chemical is transferred to a chemical reactor.
Develop an unsteady-state model for a stirred batch reactor, using the nonlinear continuous reactor model presented in Example 4.8 as a starting point. For the parameters given below, compare the
A batch reactor converts component A into B, which in turn decomposes into C: The concentrations of A and B are denoted by x1 and x2, respectively. The reactor model is: Thus, the ultimate values of
Suppose a batch reactor such as the one in figure has a gas ingredient added to the liquid feed. As long as the reaction is proceeding normally, the gas is absorbed in the liquid (where it reacts),
Fogler2 describes a safety accident in which a batch reactor was used to produce nitroanaline from ammonia and o-nitro chlorobenzene. On the day of the accident, the feed composition was changed from
Consider the batch reactor system studied by Aziz et al.,3. The two reactions, A + B → C and A + C → D, are carried out in a jacketed batch reactor, where C is the desired product and D is a
Figure E. illustrates two CSTRS in a chemical manufacturing plant. Reactants A and B must be fed to the first stirred-tank at a constant molar ratio. Reactant C is introduced to the second
In this exercise, you will evaluate the individual units at the nominal steady state for purposes of understanding how the plant would operate without recycle. Use Simulink to simulate the lull
Starting with a Simulink model of the recycle process, implement a reactor level controller using F as the manipulated variable. Confirm via simulation that control scheme Alternative 1 works
Starting with a Simulink model of the recycle process, (a) Place a tightly tuned flow controller on F. Confirm, via a step change in F0, that Alternative 2 is self-regulating; that is, the level in
Lnyben?s original proposal (1994) for the Alternative 2 control structure incorporated a reactor level controller using F0 as the manipulated variable. However, the level controller prevents
Implement Alternatives 3 and 4 using the Simulink model. This will require tuning a cascade loop to control composition in each case.(a) Evaluate the response of these controlled plants for a step
Evaluate any two of the four alternatives we have looked at in this chapter, (i.e., Exercises 23.3, 23.4a, and/or 23.6).(a) Compare the responses of each control structure to step changes in reactor
The recycle plant discussed in this chapter utilizes a composition-only model; that is, thermal effects are neglected. Appendix B contains equations and parameters that can be used to model
In Appendix E.2 three version of the cote model of the reactor/flash unit plant arc developed. One is a “full composition model” (Eqs. E.2.8 through E2- 30) that provides the relations needed to
The gain matrix in Eq. 24-1 for the plant in this chapter was obtained using analytical methods (Mathematica: see www.mathematica.com) with the reduced holdup model. An alternative way to evaluate
Using the control loops in Table E.2.7 and E.2.8 with, the full composition model created in Exercise 24.1, evaluate the use of ratio control in Loop 2 of Table 24.4. In particular, indicate why
A purge stream often is included in recycle plants, such as the reactor/flash plan discussed in this chapter, to keep the concentration of a contaminant from building up within the plant. Thus, one
Using a Simulink representation of the reactor/flash plant, add an additional feedback control loop for reactor level HR (assumed in this chapter to be perfectly controlled) by the following
If the flash unit in the example plant operates as an ideal splitter but with a non-negligible liquid holdup (e.g., 1000 kg), what would be the effect on the response of composition loop 12 in Table
Design an MPC controller for the reactor/flash unit plant and test it using a simulation of the linearized model of this plant. For purposes of this exercise, first design and implement a PI
An element X has five major isotopes, which are listed below along with their abundances. Calculate the average atomic mass, and identify the element.
Ascorbic acid, or vitamin C(C6H8O6), is an essential vitamin. It cannot be stored by the body and must be present in the diet. What is the molar mass of ascorbic acid? Vitamin C tablets are taken as
A gas contains a mixture of NH3(g) and N2H4(g), both of which react with O2(g) to form NO2(g) and H2O(g). The gaseous mixture (with an initial mass of 61.00 g) is reacted with 10.00 moles O2, and
From the information that follows, determine the mass of substance C that will be formed if 45.0 g of substance A reacts with 23.0 g of substance B. (Assume that the reaction between A and B goes to
Consider the following balanced chemical equation: A + 5B → 3C + 4Da. Equal masses of A and B are reacted. Complete each of the following with either “A is the limiting reactant because _____”;
The molecular formula of acetylsalicylic acid (aspirin), one of the most commonly used pain relievers, is C9H8O4.a. Calculate the molar mass of aspirin.b. A typical aspirin tablet contains 500 mg
What amount (moles) is represented by each of these samples?a. 20.0 mg caffeine, C8H10N4O2b. 2.72 × 1021 molecules of ethanol, C2H5OHc. 1.50 g of dry ice, CO2
How many atoms of nitrogen are present in 5.00 g of each of the following?a. Glycine, C2H5O2Nc. Calcium nitrateb. Magnesium nitrided. Dinitrogen tetroxide
Consider the following gas samples: 4.0 g of hydrogen gas, 4.0 g of helium gas, 1.0 mole of fluorine gas, 44.0 g of carbon dioxide gas, and 146 g of sulfur hexafluoride gas. Arrange the gas samples
Aspartame is an artificial sweetener that is 160 times sweeter than sucrose (table sugar) when dissolved in water. It is marketed as NutraSweet. The molecular formula of aspartame is C14H18N2O5.a.
Chloral hydrate (C2H3Cl3O2) is a drug formerly used as a sedative and hypnotic. It is the compound used to make “Mickey Finns” in detective stories.a. Calculate the molar mass of chloral
In the spring of 1984, concern arose over the presence of ethylene dibromide, or EDB, in grains and cereals. EDB has the molecular formula C2H4Br2 and until 1984 was commonly used as a plant
Anabolic steroids are performance enhancement drugs whose use has been banned from most major sporting activities. One anabolic steroid is fluoxymesterone (C20H29FO3). Calculate the percent
The stable isotopes of iron are 54Fe, 56Fe, 57Fe, and 58Fe. The mass spectrum of iron looks like the following:
Calculate the percent composition by mass of the following compounds that are important starting materials for synthetic polymers:a. C3H4O2 (acrylic acid, from which acrylic plastics are made)b.
In 1987 the first substance to act as a superconductor at a temperature above that of liquid nitrogen (77 K) was discovered. The approximate formula of this substance is YBa2Cu3O7. Calculate the
Arrange the following substances in order of increasing mass percent of carbon.a. Caffeine, C8H10N4O2b. Sucrose, C12H22O11c. Ethanol, C2H5OH
The percent by mass of nitrogen for a compound is found to be 46.7%. Which of the following could be this species?
Vitamin B12, cyanocobalamin, is essential for human nutrition. It is concentrated in animal tissue but not in higher plants. Although nutritional requirements for the vitamin are quite low, people
Fungal laccase, a blue protein found in wood- rotting fungi, is 0.390% Cu by mass. If a fungal laccase molecule contains four copper atoms, what is the molar mass of fungal laccase?
Portland cement acts as the binding agent in concrete. A typical Portland cement has the following composition:Assuming that the impurities contain no Ca, Al, or Fe, calculate the mass percent of
Express the composition of each of the following com-pounds as the mass percent of its elements.a. Formaldehyde, CH2Ob. Glucose, C6H12O6c. Acetic acid, HC2H3O2Considering your answers, which type of
Give the empirical formula of each of these compounds.
Determine the molecular formulas to which the following empirical formulas and molar masses pertain.a. SNH (188.35 g/ mol)b. NPCl2 (347.64 g/ mol)c. CoC4O4 (341.94 g/ mol)d. SN (184.32 g/ mol)
The element silver (Ag) has two naturally occurring isotopes: 109Ag and 107Ag with a mass of 106.905 amu. Silver consists of 51.82% 107Ag and has an average atomic mass of 107.868 amu. Calculate the
A sample of urea contains 1.121 g N, 0.161 g H, 0.480 g C, and 0.640 g O. What is the empirical formula of urea?
There are two binary compounds of mercury and oxygen. Heating either of them results in the decomposition of the compound, with oxygen gas escaping into the atmosphere while leaving a residue of pure
The compound adrenaline contains 56.79% C, 6.56% H, 28.37% O, and 8.28% N by mass. What is the empirical formula of adrenaline?
A compound contains only carbon, hydrogen, nitrogen, and oxygen. Combustion of 0.157 g of the compound produced 0.213 g of CO2 and 0.0310 g of H2O. In another experiment, 0.103 g of the compound
Maleic acid is an organic compound composed of 41.39% C, 3.47% H, and the rest oxygen. If 0.129 mole of maleic acid has a mass of 15.0 g, what are the empirical and molecular formulas of maleic acid?
Determine the molecular formula of a compound that contains 26.7% P, 12.1% N, and 61.2% Cl, and has a molar mass of 580 g/ mol.
Terephthalic acid is an important chemical used in the manufacture of polyesters and plasticizers. It contains only C, H, and O. Combustion of 19.81 mg terephthalic acid produces 41.98 mg CO2 and
A compound contains only carbon, hydrogen, and oxygen. Combustion of 10.68 mg of the compound yields 16.01 mg CO2 and 4.37 mg H2O. The molar mass of the compound is 176.1 g/ mol. What are the
ABS plastic is a tough, hard plastic used in applications requiring shock resistance. The polymer consists of three monomer units: acrylonitrile (C3H3N), butadiene (C4H6), and styrene (C8H8).a. A
The reaction of an element X with element Y is represented in the following diagram. Which of the equations best describes this reaction?a. 3X + 8Y ( X3Y8 b. 3X + 6Y ( X3Y6 c. X + 2Y ( XY2 d. 3X + 8Y
The element europium exists in nature as two isotopes: 151Eu has a mass of 150.9196 amu, and 153Eu has a mass of 152.9209 amu. The average atomic mass of europium is 151.96 amu. Calculate the
Silicon is produced for the chemical and electronics industries by the following reactions. Give the balanced equation for each reaction. Electric a. SiO2(s) + C(s) → Si2(s) + CO(g) arc furnace b.
Give the balanced equation for each of the following chemical reactions.a. Glucose (C6H12O6) reacts with oxygen gas to produce gaseous carbon dioxide and water vapor.b. Solid iron(III) sulfide reacts
Give the balanced equation for each of the following. a. The combustion of ethanol (C2H5OH) forms carbon dioxide and water vapor. A combustion reaction refers to a reaction of a substance with oxygen
Balance the following equations.a. Cr(s) + S8(s) ( Cr2S3(s) Heatb. NaHCO3(s) ( Na2CO3(s) + CO2(g) + H2O(g) Heatc. KClO3(s) ( KCl(s) + O2(g)d. Eu(s) + HF(g) ( EuF3(s) + H2(g)e. C6H6(l) + O2(g) (
Balance each of the following chemical equations.a. KO2(s) + H2O(l) ( KOH(aq) + O2(g) + H2O2(aq)b. Fe2O3(s) + HNO3(aq) ( Fe(NO3)3(aq) + H2O(l)c. NH3(g) + O2(g) ( NO(g) + H2O(g)d. PCl5(l) + H2O(l) (
The reusable booster rockets of the U.S. space shuttle use a mixture of aluminum and ammonium perchlorate for fuel. A possible equation for this reaction is 3Al(s) + 3NH4ClO4(s) → Al2O3(s) +
Nitric acid is produced commercially by the Ostwald process. The three steps of the Ostwald process are shown in the following equations:4NH3(g) + 5O2(g) → 4NO(g) + 6H2O(g)2NO(g) + O2(g) →
Over the years, the thermite reaction has been used for welding railroad rails, in incendiary bombs, and to ignite solid- fuel rocket motors. The reaction isFe2O3(s) + 2Al(s) → 2Fe(l) +
The reaction between potassium chlorate and red phosphorus takes place when you strike a match on a match-box. If you were to react 52.9 g of potassium chlorate (KClO3) with excess red phosphorus,
The space shuttle environmental control system handles excess CO2 (which the astronauts breathe out; it is 4.0% by mass of exhaled air) by reacting it with lithium hydroxide (LiOH) pellets to form
The element rhenium (Re) has two naturally occurring isotopes, 185Re and 187Re, with an average atomic mass of 186.207 amu. Rhenium is 62.60% 187Re, and the atomic mass of 187Re is 186.956 amu.
Bacterial digestion is an economical method of sewage treatment. The reaction Bacteria5CO2(g) + 55NH4+(aq) + 76O2(g) → C5H7O2N( s) + 54NO2-(aq) + 52H2O(l) + 109H+(aq) Bacterial tissue is an
Phosphorus can be prepared from calcium phosphate by the following reaction: 2Ca3(PO4) 2(s) + 6SiO2(s) + 10C(s) → 6CaSiO3(s) + P4(s) + 10CO(g) Phosphorite is a mineral that contains Ca3(PO4)2 plus
In the production of printed circuit boards for the electronics industry, a 0.60-mm layer of copper is laminated onto an insulating plastic board. Next, a circuit pattern made of a chemically
Consider the reaction between NO(g) and O2(g) represented below.
Consider the following reaction:4NH3( g) + 5O2( g) → 4NO( g) + 6H2O(g)If a container were to have 10 molecules of O2 and 10 molecules of NH3 initially, how many total molecules (reactants plus
Hydrogen peroxide is used as a cleaning agent in the treatment of cuts and abrasions for several reasons. It is an oxidizing agent that can directly kill many microorganisms; it decomposes upon
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