Questions and Answers of Analysis Synthesis And Design Of Chemical Processes

The addition of a heat recovery system to a process is being considered. The costs of the heat exchangers and other economic parameters are: Installed cost of new heat exchangers = $4,500,000Time
For design of an exothermic reactor with cooling, one needs to choose an approach temperature (the nominal temperature difference between the reaction zone and the cooling medium). One engineer
Are there any safety considerations in the choice of heat transfer driving force (ΔT) in Problem 12.4? Explain.Problem 12.4For design of an exothermic reactor with cooling, one needs to choose an
From the flowsheets, identify four examples of each of the following types of recycles described in this chapter:1. Recycles that reduce feed costs2. Recycles that reduce impurities in products
Recycles are also used for the following purposes. Identify four examples of each.a. Heat removalb. Flowrate controlc. Improvement of separationd. Reduction of utility requirements
From your previous courses and experience, identify four process recycle streams that serve different purposes from those identified in Problem 12.7(a) through (d).Problem 12.7Recycles are also used
What information is needed about the available utilities before a choice between them can be made for a specific heating duty?
Take a flowsheet for one of the processes and identify the reactor feed preparation, reactor, separator feed preparation, separator, recycle, and environmental control sections. Is there any
How many simple distillation columns are required to purify a stream containing four components into four “pure” products? Sketch all possible sequences.
How many simple distillation columns are required to purify a stream containing five components into five “pure” products? Sketch all possible sequences.
Illustrate a system (PFD and McCabe-Thiele diagrams) to purify two components (A and B) from a binary, homogeneous, minimum-boiling azeotrope that is pressure sensitive. The feed concentration of A
In the production of dimethyl carbonate from methanol, it is necessary to separate methanol from formal (also known as methylal—C3H8O2). However, an azeotrope exists between these two components.
In the production of diethyl ether, it is necessary to purify a stream of equimolar diethyl ether and water that is available at 1500 kPa. Suggest a method for achieving this separation. Use the
In the production of diethyl ether, assume that it is necessary to purify a stream at 1500 kPa containing 75 mol% diethyl ether, 20 mol% ethanol, and 5 mol% dimethyl ether.Assume that the UNIQUAC
Does Equation (12.1) give the number of alternative sequences for separation processes other than distillation? If so, give two examples. If not, why not? S= = [2(N-1)]! N!(N − 1)! - (12.1)
When your parents or grandparents were in college, it was not uncommon to “borrow” some “pure” ethanol (grain alcohol) from the university to add to a party punch. However, because of the
What constraints on the separation process and on the sequence are assumed in the derivation of Equation (12.1)? S= = [2(N-1)]! N!(N − 1)! - (12.1)
Figure 12.1(d) shows a nonsimple separation unit. When one says that the minimum number of simple separation units is (N – 1), these nonsimple units are not considered. Identify four other examples
Does Equation (12.1) apply to batch or semibatch separation processes? Why or why not? S= = [2(N-1)]! N!(N − 1)! - (12.1)
For the ethylbenzene process shown in Appendix B, check the design specifications for the following three pieces of equipment against the appropriate heuristics: P-301, V-302, T-302. Comment on any
You have been tasked with recommending a pump for a corrosive service by considering three manufacturers. The after-tax, internal hurdle rate is 10%. Which of the following three alternatives do you
A plant that operates at high temperatures and moderate pressures is being constructed. You have been asked to evaluate two alternatives for the gasket materials used in the plant. These gasket
A pressure vessel needs to be purchased by evaluating three different options. The after-tax, internal hurdle rate is 10%. Which of the following three alternatives do you recommend and why? Vessel
The cumulative discounted cash flow diagram for a process is shown in Figure P10.51; all numbers are given in $million and have been discounted to time t = 0. The project life is ten years after
For the drying oil process shown in Appendix B, check the design specifications for the following three pieces of equipment against the appropriate heuristics: V-501, P-501, H-501. Comment on any
For the styrene process shown in Appendix B, check the design specifications for the following three pieces of equipment against the appropriate heuristics: E-401, C-401, T-402. Comment on any
Choose one of the cases. Identify1. All required physical property data2. Sources for all data needed but not provided
Search the patent literature for kinetics information for one of the processes. Convert the provided data to a form suitable for use on a process simulator.
Develop five heuristics for reactor design.
What is the difference between the nominal annual interest rate and the effective annual interest rate? When are these two rates equal?
You work in the summer and receive three large, equal monthly paychecks in June, July, and August. You are living at home, so there are no living expenses. You use this money to pay your tuition for
The value of the Chemical Engineering Plant Cost Index (CEPCI) at the beginning of 2016 is 557. If at the same time next year the value has risen to 594, what will be the average inflation rate for
Discuss the differences and similarities between interest, inflation, and the time value of money.
What term describes the method by which a fixed capital investment can be used to reduce the tax that a company pays?
What is depreciation? Explain how it affects the economic analysis of a new chemical process.
Why is it advantageous to use an accelerated depreciation schedule?
“In general, it is better to depreciate the fixed capital investment as soon as allowable.” Give one example of when this statement would not be true.
What is the difference between after-tax profit and after-tax cash flow? When are these two quantities the same?
You need to borrow $1000 for an emergency. You have two alternatives. One is to borrow from a bank. The other is to borrow from your childhood friend Greta Ganav, who is in the “private”
Consider the following three investment schemes:9.5% p.a. (nominal rate) compounded daily10.0% p.a. (nominal rate) compounded monthly10.5% p.a. (nominal rate) compounded quarterly1. Which investment
At an investment seminar that I recently attended, I learned about something called “the Rule of 72.” According to the person in charge of the seminar, a good estimate for finding how long it
You invested $5000 eight years ago, and you want to determine the value of the investment now, at the end of year 8. During the past eight years, the nominal interest rate has fluctuated as
What are the differences between investing $15,000 at 9% p.a. for 15 years when compounded yearly, quarterly, monthly, daily, and continuously? Ignore the effect of leap years.
One bank advertises an interest rate on a certificate of deposit (CD) to be 4% compounded daily. Another bank advertises a CD with a 4.1% effective annual rate. In which CD would you invest?
You take out a new-car loan from an internet bank that compounds interest weekly and requires weekly payments. The interest rate is 5.5%. What is the weekly payment for a $20,000, five-year loan,
You want to begin an investment plan to save for your daughter’s college education. Because you believe that your newly born daughter will be a genius (just like you!), you are assuming the cost of
You begin an investment plan by putting $10,000 in an account that you assume will earn 8% annually. For the next 25 years, you add $5000/y. In anticipation of buying a house with a 15-year mortgage,
The cash flows for a bank account are described by the discrete CFD in Figure P9.22. The bank account has an effective annual interest rate of 4.5%.1. Calculate the future value of all cash flows
You begin work on June 1 and work until August 31, and receive pay on the last day of the month. Your expenses for these three months are $1500/mo. At the end of September, you make a $7000 payment,
In a tax-deferred investment plan such as a 401k, you can invest money deducted from your gross salary before taxes are withheld. Most companies provide some sort of matching contribution. Suppose
You begin to contribute to an investment plan with your company immediately after graduation, when you are 23 years old. Your contribution plus your company’s contribution totals $6000/y. Assume
A 401k (and similar plans) is an investment vehicle available to most individuals to save for retirement. The benefit is that the investment is made before taxes (by payroll deduction), and interest
You plan to finance a new car by borrowing $25,000. The interest rate is 7% p.a., compounded monthly. What is your monthly payment for a three-year loan, a four-year loan, and a five-year loan?
You have just purchased a new car by borrowing $20,000 for four years. Your monthly payment is $500. What is your nominal interest rate if compounded monthly?
You plan to borrow $200,000 to purchase a new house. The nominal interest rate is fixed at 6.5% p.a., compounded monthly.1. What is the monthly payment on a 30-year mortgage?2. What is the monthly
You just borrowed $225,000 to purchase a new house. The monthly payment (before taxes and insurance) is $1791 for the 25-year loan. What is the effective annual interest rate?
You just borrowed $250,000 to purchase a new house. The nominal interest rate is 6% p.a., compounded monthly, and the monthly payment is $1612 for the loan. What is the duration of the loan?
Your company is trying to determine whether to spend $500,000 in process improvements. The projected cash flow increases based on the process improvements are as follows:The alternative is to do
A home-equity loan involves borrowing against the equity in a house. For example, if your house is valued at $250,000 and you have been paying the mortgage for a sufficient amount of time, you may
It is necessary to evaluate the profitability of proposed improvements to a process prior to obtaining approval to implement changes. For one such process, the capital investment (end of year 0) for
You are evaluating the profitability potential of a process and have the following information. The criterion for profitability is a 15% rate of return over ten operating years. The equipment has
In Problem 9.33, the after-tax cash flow figures were generated using a taxation rate of 45% and a straight-line depreciation over the eight-year project. Calculate the yearly after-tax cash flows if
What are the MACRS depreciation allowances for recovery periods of four, six, and nine years?
For a new process, the land was purchased for $10 million. The fixed capital investment, paid at the end of year 0, is $165 million. The working capital is $15 million, and the salvage value is $15
The following are results of a recent evaluation of two projects. Which would you choose? Defend your choice. Your opportunity cost for capital is 15%. NPV DCFROR Project A10 55% Project B10,00016%
The evaluation of a project requiring a large capital investment has yielded an NPV (net present value) of $20 × 106. If the internal hurdle rate for this project was set at 10% p.a., will the
Explain the concept of an incremental economic analysis.
When comparing two pieces of equipment for a given service, if each piece of equipment has the same life and each costs the same, would the amount of maintenance required for the equipment be an
What economic criterion would you use to choose the best piece of equipment among three alternatives, each with a different operating cost, capital cost, and equipment life?
Do you agree with the statement “Monte-Carlo simulation enables the design engineer to eliminate risk in economic analysis”? Please explain your answer.
In evaluating a large project, what are the advantages and disadvantages of probabilistic analysis?
For the following problems, unless stated otherwise, you may assume that the cost of land, L, and the salvage value, S, of the plant are both zero.The following expenses and revenues have been
From the data given in Table P10.12, determine the following information regarding the calculations performed for this analysis:What taxation rate was assumed?What was the total fixed capital
For the following problems, unless stated otherwise, you may assume that the cost of land, L, and the salvage value, S, of the plant are both zero.The projected costs for a new plant are given below
Consider the following two new chemical plants, each with an initial fixed capital investment (year 0) of $15 × 106. Their cash flows are as follows:Calculate the NPV of both plants for interest
In a design, you have the choice of purchasing one of the following batch reactors:If the internal rate of return for such comparisons is 9% p.a., which of the alternatives is least costly?
Suggest some ideas for the chlorine problem in Example 4.2.Example 4.2Maintaining a swimming pool, either at home or in a public facility, is both expensive and time consuming. The water must be
Four products (A-D) are made in a batch processing plant. The times (in hours) required for each piece of equipment for each product are shown in Table P3.22.Using this information, answer the
What are the three principal types of diagrams used by process engineers to describe the flow of chemicals in a process? On which of these diagrams would you expect to see the following items?The
A problem has occurred in the measuring element of a level-indicating controller in a batch reactor. To what principal diagram should you refer in order to troubleshoot the problem?
Why is it important for a process engineer to be able to review a three-dimensional model (actual or virtual/electronic) of the plant prior to the construction phase of a project?
Name five things that would affect the locations of different pieces of equipment when determining the layout of equipment in a process unit.
Why are accurate plant models (made of plastic parts) no longer made as part of the design process? What function did these models play and how is this function now achieved?
In the context of process modeling tools, what do OTS and ITS stand for?
What is augmented reality? Give one example of it.
What are the two principle methods for the layout of process equipment in a chemical plant?
What problems would you foresee in naming equipment in a process that had a unit number of 10?
What diagram would you refer to in order to estimate the frictional loss through a certain piping run within a process?
In the vast majority of cases what is the final control element in a process control loop?
What is the most effective way of communicating information about a process?
Vessel V-307 is to be replaced in a plant with a vessel that is designed to withstand a higher pressure and which has a larger volume. Should this vessel be numbered V-307 to correspond with the
There are two common reasons for elevating the bottom of a tower by means of a “skirt.” One reason is to provide enough NPSHA for bottoms product pumps to avoid cavitation. What is the other
Which of the principal diagrams should be used to do the following:Determine the number of trays in a distillation column?Determine the top and bottom temperatures in a distillation column?Validate
What is the purpose(s) of a pipe rack in a chemical process?
When would a structure-mounted vertical plant layout arrangement be preferred over a grade-mounted, horizontal, in-line arrangement?
A process that is being considered for construction has been through several technical reviews; block flow, process flow, and piping and instrumentation diagrams are available for the process.
During a retrofit of an existing process, a vessel used to supply the feed pump to a batch reactor has been replaced because of excessive corrosion. The vessel is essentially identical to the
The production of ethylbenzene is described in Appendix B, Project B.2. From the PFD (Figure B.2.1) and accompanying stream table (Table B.2.1), determine the following:1. The single-pass conversion
The formation of styrene via the dehydrogenation of ethylbenzene is a highly endothermic reaction. In addition, ethylbenzene may decompose to benzene and toluene and also may react with hydrogen to
Consider the following statement: “If a reactant (G) in a process is a gas at the feed conditions, subsequent separation from the reactor effluent is difficult, hence unused G cannot be

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