Questions and Answers of Chemical Engineering Design

Figure 20.27 shows the flowsheet for a process for the production of gasoline (mainly octane) from an olefins feed (propane, propene, and butene). The feed to the process is heated in E-100, and then
Figure 20.26 shows the flowsheet for a process for the production of G from A. The feed stream of A (entering through valve V-1) is mixed with a makeup stream of \(B\) (entering through valve
A stream of hot gases at \(1,000^{\circ} \mathrm{C}\), having a specific heat of \(6.9 \mathrm{cal} / \mathrm{mol}-{ }^{\circ} \mathrm{C}\), is used to preheat air fed to a furnace. Because of
An ideal gas, with \(C_{p}=7 \mathrm{cal} / \mathrm{mol}-{ }^{\circ} \mathrm{C}\), is compressed from 1 to \(50 \mathrm{~atm}\) while its temperature rises from 25 to \(150^{\circ} \mathrm{C}\). How
Superheated steam at \(250 \mathrm{psia}\) and \(500^{\circ} \mathrm{F}\) is compressed to \(350 \mathrm{psia}\). The isentropic efficiency of the compressor is \(70 \%\). For the compressor, compute
Steam at \(400^{\circ} \mathrm{F}, 70 \mathrm{psia}\), and \(100 \mathrm{lb} / \mathrm{hr}\) is compressed to 200 psia. The electrical work is \(4.1 \mathrm{~kW}\). Determine the:(a) Lost work(b)
The rate of heat transfer between Reservoir A at \(200^{\circ} \mathrm{F}\) and Reservoir B at \(180^{\circ} \mathrm{F}\) is \(1,000 \mathrm{Btu} / \mathrm{hr}\).(a) Compute the lost work.(b) Adjust
Nitrogen gas at \(25^{\circ} \mathrm{C}\) and \(1 \mathrm{~atm}\), with \(C_{p}=7 \mathrm{cal} / \mathrm{mol}-\mathrm{K}\), is cooled to \(-100^{\circ} \mathrm{C}\) at \(1 \mathrm{~atm}\). Assuming
An equimolar stream of benzene and toluene at \(1,000 \mathrm{lbmol} / \mathrm{hr}\) and \(100^{\circ} \mathrm{F}\) is mixed with a toluene stream at \(402.3 \mathrm{lbmol} / \mathrm{hr}\) and
Consider the cooler, \(\mathrm{H} 2\), in the monochlorobenzene separation process in Figures 7.21 and 7.22. Assume that the heat is transferred to an infinite reservoir of cooling water at
Two streams, each containing \(0.5 \mathrm{lb} / \mathrm{hr}\) steam at \(550 \mathrm{psia}\), are mixed as shown in Figure 10.29:(a) Compute the heat loss to an environmental reservoir at
\(1,000 \mathrm{lb} / \mathrm{hr}\) of saturated water at \(600 \mathrm{psia}\) is superheated to \(650^{\circ} \mathrm{F}\) and expanded across a turbine to \(200 \mathrm{psia}\) as illustrated in
Superheated steam at \(580^{\circ} \mathrm{F}\) and \(500 \mathrm{psia}\) is expanded across a turbine, as shown in Figure 10.31, to \(540^{\circ} \mathrm{F}\) and 400 psia. \(0.9 \mathrm{~kW}\) of
Calculate the minimum rate of work in watts for the gaseous separation at ambient conditions indicated in Figure 10.32.Figure 10.32:- Feed Separator kmol/hr Cz 30 Cz 200 nC4 370 nC5 350 nC6 50 Figure
Calculate the minimum rate of work in watts for the gaseous separation at ambient conditions of the feed into the three products shown in Figure 10.33.Figure 10.33:- Product 1 kmol/hr EB 144.0 PX 1.0
For the adiabatic flash operation shown in Figure 10.34, calculate the following:(a) Change in availability function \(\left(T_{0}=100^{\circ} \mathrm{F}\right)\)(b) (b) Lost work(c) Thermodynamic
Consider the results of an ASPEN PLUS simulation of the flash vessel in Figure 10.35:Heat is obtained from a large reservoir at \(150^{\circ} \mathrm{F}\). Calculate the following:(a) Rate of heat
A partial condenser operates as shown in Figure 10.36. Assuming that \(T_{0}=70^{\circ} \mathrm{F}\), calculate the following:(a) Condenser duty(b) Change in availability function(c) Lost work(d)
A light-hydrocarbon mixture is to be separated by distillation as shown in Figure 10.37 into ethane-rich and propane-rich fractions. Based on the specifications given and use of the
A mixture of three hydrocarbons is to be separated into three nearly pure products by thermally coupled distillation at \(1 \mathrm{~atm}\) as shown in Figure 10.38.Based on the specifications given
Consider the hypothetical perfect separation of a mixture of ethylene and ethane into pure products by distillation as shown in Figure 10.39.Two schemes are to be considered: conventional
Consider a steam engine that operates in a Rankine cycle as shown in Figure 10.40:The turbine exhaust is a saturated vapor.(a) Find the saturation temperature of the turbine exhaust.(b) For an
A reactor is to be designed for the oxidation of sulfur dioxide, with excess oxygen from air, to sulfur trioxide. The entering feed, at \(550 \mathrm{~K}\) and \(1.1 \mathrm{bar}\), consists of
For the revised propane refrigeration cycle in Figure 10.21, let the isentropic efficiencies of the turbine and compressor be 0.9 and 0.7 , respectively. Compute the following:(a) Lost work for the
Alter the design of the cyclohexane process in Example 10.5 to reduce the lost work and increase the thermodynamic efficiency. Use a simulation program to complete the material and energy balances,
The chilled-water plant at the University of Pennsylvania sends chilled water to the buildings at \(42^{\circ} \mathrm{F}\) and receives warmed water at \(55^{\circ} \mathrm{F}\). A refrigerant is
Consider the solar or waste-heat refrigeration cycle in Figure 10.41, which was proposed by Sommerfeld (2001). In addition to the conventional refrigeration loop, a portion of the condensate is
Four streams are to be cooled or heated:(a) For \(\Delta T_{\text {min }}=10^{\circ} \mathrm{C}\), find the minimum heating and cooling utilities. What are the pinch temperatures?(b) Design a heat
(a) For \(\Delta T_{\min }=10^{\circ} \mathrm{C}\), find the minimum utility requirements for a network of heat exchangers involving the following streams:(b) Repeat (a) for the following streams:(c)
Consider the design of a network of heat exchangers that requires the minimum utilities for heating and cooling. Is it true that a pinch temperature can occur only at the inlet temperature of a hot
The PFD in Figure 11.58 shows a process for the manufacture of \(\mathrm{X}\) and \(\mathrm{Y}\). The process feed is heated in furnace \(\mathrm{F}-100\) to \(800^{\circ} \mathrm{C}\) and is then
Consider the following heating and cooling demands:A HEN is to be designed with \(\Delta T_{\text {min }}=30^{\circ} \mathrm{C}\) :(a) Find the MER targets.(b) Design a subnetwork of heat exchangers
Consider the process flowsheet in Figure 11.59 where the duties required for each heat exchanger are in MW, and the source and target stream temperatures are:(a) The flowsheet calls for \(990
Consider the network of heat exchangers in Figure 11.60:(a) Determine \(N_{H X, \text { min }}\).(b) Identify the heat loop.(c) Show one way to break the heat loop using \(\Delta T_{\min }=10^{\circ}
To exchange heat between four streams with \(\Delta T_{\text {min }}=20^{\circ} \mathrm{C}\), the HEN in Figure 11.61 is proposed. Determine whether the network has the minimum utility requirements.
A process has streams to be heated and cooled above its pinch temperatures as illustrated in Figure 11.62. Complete a design that satisfies MER targets with the minimum number of heat
Consider a process with the following streams:(a) Compute \(\Delta T_{\text {thres }}\) as well as the minimum external heating and cooling requirements as a function of \(\Delta T_{\text {min
Design a HEN to meet the MER targets for \(\Delta T_{\text {min }}=10^{\circ} \mathrm{C}\) and \(N_{H X, \text { min }}\) for a process involving five hot streams and one cold stream as introduced by
The PFD in Figure 11.63 shows a process in which two liquid products, A and B, are produced from a feed stream of raw material R. In the process, the reactor feed is preheated to \(300^{\circ}
Consider a process with the following streams:When \(\Delta T_{\text {min }}=10^{\circ} \mathrm{C}\), the minimum utilities for heating and cooling are \(237 \mathrm{~kW}\) and \(145 \mathrm{~kW}\),
Consider a process with the following streams:(a) Determine MER targets for \(\Delta T_{\text {min }}=10^{\circ} \mathrm{C}\).(b) Design a HEN for MER using no more than 10 heat exchangers (including
Figure 11.64 presents the PFD of a process for the production of organic fibers (Smith, 2005). In the process, the organic solvent is removed from the fibers in dryer D-100 using circulated warmed
Design a heat exchanger network for MER with at most 15 heat exchangers (including utility heaters) and \(\Delta T_{\text {min }}=10^{\circ} \mathrm{C}\) for the following streams:When MER targets
Figure 11.65 presents the PFD of a process for the recovery of methane from a feed stream consisting of \(75 \%\) methane and \(25 \%\) nitrogen. The process feed is first cooled from 90 to
Design a heat exchanger network for MER with at most 18 heat exchangers (including utility heaters) and \(\Delta T_{\text {min }}=10^{\circ} \mathrm{C}\) for the following streams:When MER targets
In Example 11.13, HENs are designed for a process involving two hot and two cold streams. Note that three designs are proposed: (1) involving only HP steam and cooling water that meets the \(N_{H X,
The following table presents stream data for a background process.(a) Compute MER targets for this process at \(\Delta T_{\text {min }}=20^{\circ} \mathrm{C}\).(b) Design a HEN to meet the MER
The following table presents residual heat flows in the enthalpy cascade of a process computed at \(\Delta T_{\text {min }}=10^{\circ} \mathrm{C}\) (Smith, 2005):(a) It is desired to efficiently heat
A HEN is to be designed to meet MER targets for the following stream data:(a) Compute MER targets for this process at \(\Delta T_{\text {min }}=10^{\circ} \mathrm{C}\).(b) Design a HEN to meet the
In Example 12.7, an existing exchanger is used to transfer sensible heat between toluene and styrene streams. A minimum approach temperature of \(31.3^{\circ} \mathrm{F}\) is achieved. Design a new
A heat exchange system is needed to cool \(60,000 \mathrm{lb} / \mathrm{hr}\) of acetone at \(250^{\circ} \mathrm{F}\) and 150 psia to \(100^{\circ} \mathrm{F}\). The cooling can be achieved by
A trim heater is to be designed to heat \(116,000 \mathrm{lb} / \mathrm{hr}\) of \(57 \mathrm{wt} \%\) ethane, \(25 \mathrm{wt} \%\) propane, and \(18 \mathrm{wt} \%\) n-butane from 80 to
Design a 1-4 shell-and-tube heat exchanger to cool \(60,000 \mathrm{lb} / \mathrm{hr}\) of \(42^{\circ} \mathrm{API}\) kerosene from 400 to \(220^{\circ} \mathrm{F}\) by heating a \(35^{\circ}
Hot water at \(100,000 \mathrm{lb} / \mathrm{hr}\) and \(160^{\circ} \mathrm{F}\) is cooled with \(200,000 \mathrm{lb} / \mathrm{hr}\) of cold water at \(90^{\circ} \mathrm{F}\), which is heated to
A horizontal 1-4 heat exchanger is used to heat gas oil with saturated steam. Assume that \(h_{o}=1,000 \mathrm{Btu} / \mathrm{hr}^{-}-\mathrm{ft}^{2}{ }^{\circ} \mathrm{F}\) for condensing steam and
An alternative heating medium for Exercise 12.6 is a distillate:Determine the tube-side velocity, number and length of tubes, and shell diameter for a 1-6 shell-and-tube heat exchanger using the
Ethylene glycol at 100,000 \(\mathrm{lb} / \mathrm{hr}\) enters the shell of a 1-6 shell-and-tube heat exchanger at \(250^{\circ} \mathrm{F}\) and is cooled to \(130^{\circ} \mathrm{F}\) with cooling
In Example 13.1, an absorber with an absorbent rate of \(237 \mathrm{kmol} / \mathrm{hr}\) and 4 equilibrium stages absorbs \(90 \%\) of the entering \(n\)-butane. Repeat the calculations for:(a)
The feed to a distillation tower consists of \(14.3 \mathrm{kmol} / \mathrm{hr}\) of methanol, \(105.3 \mathrm{kmol} / \mathrm{hr}\) of toluene, \(136.2 \mathrm{kmol} / \mathrm{hr}\) of ethylbenzene,
A mixture of benzene and monochlorobenzene is to be separated into almost pure products by distillation. Determine an appropriate operating pressure at the top of the tower.
In a reboiled absorber, operating as a deethanizer at 400 psia to separate a light hydrocarbon feed, conditions at the bottom tray are:Liquid Phase Molar flow = 1, \(366 \mathrm{lbmol} /
A distillation tower with sieve trays is to separate benzene from mono-chlorobenzene. Conditions at a plate near the bottom of the column are:Vapor Phase Mass flow rate \(=24,850 \mathrm{lb} /
Water is to be used to absorb acetone from a dilute mixture with air in a tower packed with 3.5-in. metal Pall rings. Average conditions in the tower are:\[\text { Temperature }=25^{\circ} \mathrm{C}
Liquid oxygen is stored in a tank at \(-298^{\circ} \mathrm{F}\) and 35 psia. It is to be pumped at \(100 \mathrm{lb} / \mathrm{s}\) to a pressure of \(300 \mathrm{psia}\). The liquid oxygen level in
Use a simulator to design a compression system with intercoolers to compress \(600 \mathrm{lb} / \mathrm{hr}\) of a mixture of \(95 \mathrm{~mol} \%\) hydrogen and \(5 \mathrm{~mol} \%\) methane at
Superheated steam available at \(800 \mathrm{psia}\) and \(600^{\circ} \mathrm{F}\) is to be expanded to a pressure of \(150 \mathrm{psia}\) at the rate of \(100,000 \mathrm{lb} / \mathrm{hr}\).
Propane gas at \(300 \mathrm{psia}\) and \(150^{\circ} \mathrm{F}\) is sent to an expansion turbine with an efficiency of \(80 \%\). What is the lowest outlet pressure that can be achieved without
(a) Consider the flash separation process shown in Figure 7.1. If using ASPEN PLUS, solve all three cases using the MIXER, FLASH2, FSPLIT, and PUMP modules and the RK-SOAVE option set for
As discussed in Example 6.7, toluene \(\left(\mathrm{C}_{7} \mathrm{H}_{8}\right)\) is to be converted thermally to benzene \(\left(\mathrm{C}_{6} \mathrm{H}_{6}\right)\) in a hydrodealkylation
As discussed in Example 6.7, the following stream at \(100^{\circ} \mathrm{F}\) and 484 psia is to be separated by two distillation columns into the Products \(1-3\) in the following table.Two
Complete a simulation of the entire process for the hydrodealkylation of toluene in Figure 6.14. Initially, let the purge/recycle ratio be 0.25 ; then, vary this ratio and determine its effect on the
(a) Complete a steady-state simulation of the vinyl-chloride process in Figure 2.6. First, create a simulation flowsheet. Assume that:Cooling water is heated from 30 to \(50^{\circ}
For the monochlorobenzene separation process in Figure 7.14, the results of an ASPEN PLUS simulation are provided in the multimedia modules under ASPEN \(\rightarrow\) Principles of Flowsheet
Cavett Problem. A process having multiple recycle loops formulated by R.H. Cavett [Proc. Am. Petrol. Inst., 43, 57 (1963)] has been used extensively to test tearing, sequencing, and convergence
Use a process simulator to model a two-stage compression system with an intercooler. The feed stream consists of \(95 \mathrm{~mol} \%\) hydrogen and \(5 \mathrm{~mol} \%\) methane at \(100^{\circ}
Consider the ammonia process in which \(\mathrm{N}_{2}\) and \(\mathrm{H}_{2}\) (with impurities \(\mathrm{Ar}\) and \(\mathrm{CH}_{4}\) ) are converted to \(\mathrm{NH}_{3}\) at high pressure
The feed (equimolar A and B) to a reactor is heated from \(100^{\circ} \mathrm{F}\) to \(500^{\circ} \mathrm{F}\) in a \(1-2\) parallel-counterflow heat exchanger with a mean overall heat-transfer
Consider the simulation flowsheets in Figure 7.36, which were prepared for ASPEN PLUS. The feed stream, S1, is specified, as are the parameters for each process unit.Complete the simulation
Use a process simulator to determine the flow rate of saturated vapor benzene at \(176.2^{\circ} \mathrm{F}\) and \(1 \mathrm{~atm}\) to be mixed with \(100 \mathrm{lbmol} / \mathrm{hr}\) of liquid
A distillation tower is needed to separate an equimolar mixture at \(77^{\circ} \mathrm{F}\) and \(1 \mathrm{~atm}\) of benzene from styrene. The distillate should contain \(99 \mathrm{~mol} \%\)
Use a process simulator to determine the heat required to vaporize \(45 \mathrm{~mol} \%\) of a liquid stream entering an evaporator at \(150^{\circ} \mathrm{F}\) and \(202 \mathrm{psia}\) and
For an equimolar mixture of \(n\)-pentane and \(n\)-hexane at \(10 \mathrm{~atm}\), use a process simulator to compute:(a) The bubble-point temperature.(b) The temperature when the vapor fraction is
Hot gases from the toluene hydrodealkylation reactor are cooled and separated as shown in the flowsheet of Figure 7.37. In a steady-state simulation, can the composition of the recycle stream be
Find the number of recycle loops, the optimal number of tear streams, and the corresponding calculation sequence for the process flowsheet in Figure 7.38.Figure 7.38:- Figure 7.38 Process flowsheet.
Given the feed streams and the parameters of the process units as shown in Figure 7.38, complete the simulation flowsheet for ASPEN PLUS and show the calculation sequence (i.e., complete the
Given the feed streams and the parameters of the process units as shown in Figure 7.39, complete the simulation flowsheet for ASPEN PLUS and show the calculation sequence (i.e., complete the
Convert the process flowsheet in Figure 7.22 into a flowsheet for mass-balance simulation Task-1. List the model equations, the variables to be specified, and the variables to be calculated.Figure
For the streams listed in Table 7.9 (cyclohexane process) and Table 7.13 (HDA process), specify (or select) a pressure (or temperature), and calculate temperature (or pressure). Indicate the reasons
For the following simulation problems, consult Table 7.2 and list the design decision variables. (a) An equimolar mixture of benzene and toluene in a process stream is in the liquid state at \(300
The process flowsheet and list of variables to specify for the HDA process are given in Figure 7.24 and Table 7.14. Perform simulations with any process simulator to match the results given in Tables
Consider a binary equimolar mixture of acetone and chloroform at \(300 \mathrm{~K}\) and \(1 \mathrm{~atm}\). Because this mixture forms a binary azeotrope, methyl- \(n\)-pentyl ether solvent is used
When the third tPA cultivator in Example 2.3 is added to the cultivators in Example 7.6, as shown in Figure 7.27a, a significant time strain is placed on the process because the combined feed,
A system of three parallel reactions (Trambouze and Piret, 1959) involves the following reaction scheme:\[\mathrm{A} \xrightarrow{k_{1}} \mathrm{~B} \quad \mathrm{~A} \xrightarrow{k_{2}} \mathrm{C}
Repeat Exercise 8.1, taking the first two reactions as first order, and the last as second order with \(k_{1}=0.02 \mathrm{~min}^{-1}, k_{2}=0.2 \mathrm{~min}^{-1}\), and \(k_{3}=2.0 \mathrm{~L} /
For the reaction system:where \(r_{1}=k_{1} C_{\mathrm{A}}, r_{2}=k_{2} C_{\mathrm{C}}, r_{3}=k_{3} C_{\mathrm{A}}\); and \(r_{4}=k_{4} C_{\mathrm{A}}\). The rate constants are \(k_{1}=\mathrm{a}
In Example 8.4, choose methane and hydrogen as independent components. Derive relationships for the remaining components in terms of methane and hydrogen.Data From Example 8.4:- Construct the
Carry out a modified design for an ammonia converter in Example 8.5 consisting of three diabatic reactor bed sections, each of \(2 \mathrm{~m}\) diameter and \(2 \mathrm{~m}\) length (note that the
Cumene process with drag (purge) streams. In Example 8.7, a process for producing cumene by the alkylation of benzene with propylene is described. The flowsheet for the process is given in Figure
The feed to a pentane isomerization process consists of \(650 \mathrm{kmol} / \mathrm{hr}\) of n-pentane and \(300 \mathrm{kmol} / \mathrm{hr}\) of isopentane. The effluent from the catalytic
Stabilized effluent from a hydrogenation unit as given below is to be separated by ordinary distillation into five relatively pure products. Four distillation columns will be required. According to

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