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Recommendations for case study reports for chemical engineering design courses

 

Final report: (See an example checklist such as your instructor might use.)  Use font 12 (except for tables) and 1.5 or double space.

·         Transmittal memo:  Name of company centered at top.  On left side: To (your imaginary boss, not the instructor), From (you), Date, Subject.  Indicate what report is attached. Give conclusions and recommendations, with key information such as annual production rates (in tonne or metric ton per year) of products that meet specifications, fraction of primary feed component converted to sellable products (overall conversion), total capital investment in $ million (FCIL + L + WC), net present value in $ million, discounted rate of return, discounted payback period, annual cost of manufacturing, critical assumptions, concerns about potential safety or environmental problems, and your recommendations on whether to build, not build, or improve the design of the plant.  Use 3 significant figures for data.  One page only.  If the NPV is negative with the current selling price of the product (or purchase price of raw material), instead of NPV and DCFRR give the minimum required selling price (or maximum purchase price), i.e. that which would give 0 NPV.  This is not the place to tell all the things you tried; your boss wants to know your conclusions, not what you did.

·         Summary:  Title of report.  “Summary” centered.  Key information, probably close to what’s in the transmittal memo.  The reason for duplicating the key information is that the transmittal memo is likely to be separated from the report.   Two pages max.

·         Contents: Use appropriate section headings with page numbers, including the appendices with their titles.  This requires that all pages be numbered.   A separate page should be used for figures and tables, with both numbers and titles of each given.

·         Body:

  1. Optional: Background information, such as uses for the product, its history, the chemical reactions involved, feedstocks, international production rates versus year, industrial practice, etc.  You can copy figures or even text, provided that you tell where you took them from.  No more than 3 pages.
  2. Description of your optimal process, in words.  Approximately 3 pages.  Refer to the pfd and to the real equipment (as opposed to fictional units that may have been used in the computations.)  Refer to the equipment and utility pages described below by table number.
  3. The pfd of your final process in landscape mode, preferably prepared using Visio (see below).  Each entering stream and exit stream must have both a number and a name.  MUST NOT be the pfd created by your simulator (UniSim, Aspen Plus, HYSYS, etc.) – put this in an appendix.  Show only real streams and units, and not fictitious things such as mixers, the bypass stream used to model a fluidized-bed reactor, or the extra heat exchanger used to find the area when both phase change and temperature change occur.
  4. Stream table for your pfd.  Show T, P, fraction vapor, total molar flow rate, total mass flow rate, molar flow rates of all components, and any other important properties, in SI units.  Use a reasonable number of significant figures (see below; no more than 4) and do not use the E format.  Again, this table should show the actual streams on the pfd, and not any fictional streams that may have been used in the modeling.  If the stream table is on the same page as the pfd, use a font size no smaller than 10.
  5. Equipment Table showing all equipment, including size, type, material of construction and current cost of each piece of equipment.  Each should be identified by a name as well as the designation code used on the pfd (e.g., T-401; acetone absorption column).  Not the page from CAPCOST.
  6. Utility Table showing all utilities, including type, unit (equipment) associated with that utility, flow rate, T, P, annual cost.
  7. Discussion of how your optimal process differs from the base case.  Describe other things you tried that either didn’t work or didn’t improve NPV.  Include a table summarizing everything you tried.  (Try to impress the instructor with all the work you did.)  Also, describe things you’d like to have tried but didn’t have time for, with reasoning.

·         Appendices:  The appendices should enable the reader to tell exactly how you arrived at the results summarized in the body of the report, including the simulator’s pfd and stream table for your optimal design, all calculations, and the sources of all data (see References below). Provide sufficient information that the professor can understand everything you’ve done.

A.    The pfd and stream table from your simulator for your optimal design (only).  Each stream should have both a name and a number, and be arranged in ascending order.

B.     For each piece of equipment in your optimal design, describe what it’s supposed to do, its feed and product streams, and how you designed it in words, equations and calculations (with numbers and units).  Include sizing, utility usage, costs, pressure drop, etc.  Define symbols used in equations.   Appropriate units must accompany all numbers and conversion factors must include units.  If you used a simulator for the calculations, list the specifications used for each piece of equipment. 

C.    For heat exchangers, print out the temperature versus heat flow plots and the worksheets with T, P, fraction vapor for each stream entering and leaving.  Give your hand calculations of area, including references for all sources of data. 

D.    For reactors, print out the results from your simulator.  For plug-flow and fluidized-bed reactors, print out the plots of temperature, pressure, and the molar flow rate or mole fraction of each component versus distance down the reactor.  Cite references by number for the sources of all data and computational methods.  Include any hand calculations you performed, e.g. for the volume of the reactor, heat transfer surface area, pressure drop, amount of catalyst, kinetics, etc.

E.     For strippers, absorbers, distillation columns print out a plot of the mole fraction of each component through the column.  Show your calculations for sizing and pressure drop, along with a printout of the key sizing pages from your simulator.

F.     For pumps, compressors and vessels show how each was sized and its utility requirement determined. For motor size for a compressor, tell what efficiency you used and cite the reference for the source of this efficiency.  (The driver for a compressor MUST have a larger power requirement than the compressor.)

G.    Give calculations for the following that are shown in CAPCOST: initial amount and cost of an expensive material such as catalyst or extraction agent;  annual makeup of this material; liquid and gas waste disposal costs; credit for a waste stream burned as fuel.

H.    CAPCOST.  Print each page except that giving the constants for equipment costing.

·         References:  Wherever information is given, data are shown or a calculation method is used, cite a reference for the source by number. That is, where did you get it?  Examples would be reasons for choices of materials of construction, U values for heat exchangers, and costs of chemicals, utilities, and equipment.  These references should be listed by number on a page titled “References” and not “Bibliography.”  Note that it is not sufficient to merely list these – they must be cited in the text and in the appendices as they are used.  For an article, include the authors' names, article’s title, name of the magazine or journal, volume number, date, and pages.  For a book, include the author's name, title, publisher, publisher’s city, date of publication, page numbers used.  Reference to a web site should include the URL site, title, and as much other information as you can determine, such as the authors, the company or university, and the date it was posted or updated.

·         Computer files:  Include a CD with all your computer files (e.g., UniSim, Aspen Plus, HYSYS, Excel, CAPCOST, Word, Visio) for your final design.  Alternately, you can email these to the instructor prior to submitting the final printed report.

·         Figures and tables: Each figure and table must be numbered consecutively, have a caption telling what’s in it, and be referred to by number and described in the text.  This includes stream tables and pfd's.  Each should appear immediately following the point where it is first referred to in the text.  Numbers and captions should be above tables and below figures.  To the extent possible, figures and tables should be understandable without reading the text, and vice versa.

·         Presentation of calculations Take care to define all symbols and to explain each step of your calculations.  If you wish to print out computations from software such as MathCAD, MATLAB or Excel insert sufficient comments for each step to be clear.  If the same symbols are used in more than one place, it may be more convenient to have a Table of Nomenclature at the beginning of the report.  

  1. Give SI units and abbreviations for each symbol.  Such units should never be plural, e.g. g/s and not gms/s.
  2. Use only one symbol for each parameter.
  3. A given symbol must represent only one parameter.

·         Significant figures:  Use the appropriate number of significant figures in the cover letter, summary, and body; generally 3 and never more than 4. That includes tables.  If you do not use CAPCOST, the Excel spreadsheets for economics calculations should show numbers as $million.  That is, for example, $1,523,489.56 should be shown as $1.52 million.  You can show more significant figures in the appendices, but don’t be ridiculous.  Plot results where possible, e.g. single-pass conversion versus reactor P.

·         Writing:  The most important thing is that the reader should have no doubt about what you mean, i.e. your writing must be clear and understandable.  Use precise and professional technical language.   Remember, to be regarded as a professional engineer you must communicate in speaking and writing as an educated engineer.  Use Word’s spelling and grammar checker, but don’t trust the spell checker for technical words – it may suggest a non-technical word with a totally different meaning.    Don’t use long and convoluted sentences.  Take care using “which”; it always refers to the immediately preceding word.  Take care in using “this” or “these” as it may leave the reader wondering what you’re referring to.  Use the past tense only in describing what you’ve done, present in describing your results, and future in talking about the plant to be built.  Common spelling problems include the use of "seperate" rather than "separate," "it's" as a possessive, and “this data” or “data is” rather than “these data” and “data are.”  Remember, there is no "per" in "separate" and that “data” is the plural form of the Latin noun “datum.”   

 

Oral report or exam:

·         Be prepared to explain how you obtained all results; how all of the equipment works; why you tried your various modifications to the base case; how your process simulator and CAPCOST performed their calculations; the definitions of all terminology (e.g., “discounted cash flow rate of return”); and safety, health and environmental aspects of your design.   When asked why you did something nutty, it is not acceptable to respond, “the computer let me do it.”   It is not acceptable to reply that "the calculations wouldn't converge" when asked why you didn't make some rather obvious improvement.

 

Remember, the objective is to impress your professor with the quality, quantity, and creativity of your work.

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Please email W. R. Wilcox with comments, suggestions, questions..   Last updated December 10, 2009.

 

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