CACHE Process Design Case Studies

 

 

CACHE Process Design Case Study
Vol. 4

“Alternative Fermentation Processes for Ethanol Production”

The objective of this case study is the preliminary design and
economic evaluation of a fermentation process for the production of
ethanol from a molasses feedstock. The intent is to expose the student
to some non-traditional chemical engineering processes and to the
expanding field of biotechnology. The scope of the study is such that
groups of 2-3 students should be able to complete the design in about
30 days. The major focus of this design is the creation and rational
development of a suitable process flowsheet, simulation of the
flowsheet by the simulator FLOWTRAN, and economic evaluation and cost
minimization of the final process.

 

The problem begins with the specification of the plant operating
requirements. The type of fermentor to be used as well as plant
operating conditions are left open. Suggested fermentors include batch,
CSTR, CSTR w/cell recycle as well as a novel extractive fermentor based
on the use of hollow fiber membranes (HFEF). The choice of the
fermentor will affect the nature of the flowsheet and lead to several
design alternatives which the students will have to screen before
arriving at a workable flowsheet that is ready for simulation. This
case study includes a floppy disk with input files for the simulator
FLOWTRAN as well as a program written in BASIC to evaluate the
performance of CSTR fermentors.

 

The problem statement was posed by Professors Steven LeBlanc and
Ronald L. Fournier and prepared under their supervision by the student
Samer Naser at the University of Toledo.

 

CACHE Process Design Case Study
Vol. 5

“Retrofit of a Heat Exchanger Network and Design of a Multiproduct
Batch Plant”

This volume contains two short design projects that can be developed
by groups of 2-3 students in about two weeks. As opposed to the large
projects that are commonly used in a design course, the objective of
the case study is to expose students to a greater variety of problems
and which are of current industrial significance.

 

The first problem deals with the retrofit of a heat exchanger
network consisting of 8 exchangers with 5 hot and 3 cold processing
streams as well as steam and cooling water. The layout of the network
and areas of the exchangers are also given. The objective is to
determine a retrofit design that can reduce the energy consumption
within specified limits for the capital investment and payout times.
This problem requires examination of alternatives for the level of
energy recovery, matching of streams, addition o f area, and removal or
reassignment of existing exchangers and piping. This problem can be
used to illustrate basic concepts of heat integration, as well as the
application of computer software such as Target II, THEN, MAGNETS and
RESHEX. The second desig n problem deals with the design of a batch
processing plant that has to manufacture 4 different products, all of
which require 5 similar processing steps (reaction, product recovery,
purification, crystallization and centrifuge). An important aspect of
th is problem is that the production schedule and inventory must be
anticipated at the design stage. Furthermore, this problem also
requires analyzing alternatives for merging processing tasks into
single units, and using parallel units with and without intermediate
storage. The use of Gantt charts is emphasized to examine some of these
alternatives. The case study also includes two sets of homework
problems with solutions that can be used to provide the basic
background for the two problems.

 

This case study has been prepared by the students Richard Koehler
and Brenda Raich at Carnegie Mellon University under the supervision of
Professor Grossmann who developed the problem statements and
educational material.

 

CACHE Process Design Case Study
Vol. 6

“Chemical Engineering Optimization Models with GAMS”

The objective of this case study is to provide a set of chemical
engineering problems to supplement optimization courses at both the
undergraduate and graduate level. This case study should also be useful
in other courses and to practicing engineers to learn about GAMS and
its applications.

 

GAMS is an algebraic modelling system in which the user need not be
concerned with details of providing the interfaces with various
optimization codes. Instead, the GAMS environment allows the user to
concentrate on the modelling of problems, which u ltimately is the main
skill that is required for the successful application of optimization
in practice. This case study covers applications at various levels of
complexity in the following areas: (a) Planning and scheduling of batch
and continuous proce sses, (b) Chemical and phase equilibrium, (c)
Design of heat exchanger networks, distillation columns and batch
processes, (d) Synthesis of reaction paths, heat exchanger networks and
distillation sequences, (e) Optimization of dynamic and distributed par
ameter models. These problems are modelled as linear, nonlinear and
mixed-integer optimization problems.

 

This case study describes in detail the formulation and solution of
a total of 22 optimization problems that cover the different areas
cited above. Exercises are also given for each problem. In addition,
the case study includes:

  1. Special student version of GAMS for IBM-PC and compatibles in 3 1/2
    in diskettes. The MINOS, ZOOM and DICOPT++ codes are inclu ded in this
    GAMS version which can handle problems with up to 1000 nonzero elements
    in the Jacobian matrix.
  2. GAMS input files for all the problems; these are extensively
    documented.
  3. GAMS User’s Guide.

This case study has been prepared by faculty and students from
Carnegie Mellon University, Northwestern University and Princeton
University under the coordination of Ignacio E. Grossmann. GAMS
Development Corporation, the Licensing Technology Office at Stanford
University, XMP Optimization Software and Sunset Systems have donated
the computer software for this case study.

 

CACHE Process Design Case Study
Vol. 7

“Design of an Ethylbenzene Production Plant- Preliminary Design and
Economic Analysis”

The objective of this case study is the
preliminary design and economic evaluation of an alkylation process for
the production of ethylbenzene from ethylene and benzene. The intent is
to expose the student to a traditional chemical engineering process.
The scope of the study is such that groups of 3-4 students should be
able to complete the design in 3 months. The major focus of this design
is the creation and development of a suitable process flowsheet,
simulation of the flowsheet by the simulator HYSYS, economic evaluation
and cost minimization, and HAZOP analysis of the final process.

The problem begins with a statement of
the design specifications. Students are then required to consider
alternatives for the reactor type (fixed or fluidized bed), reactor
conditions (liquid or vapor phase) and separation scheme. These choices
affect the layout of the flowsheet and lead to several design
alternatives. Students are expected to analyze the various process
alternatives based on economic, safety, and environmental factors.
Included in this case study is a floppy disk containing the HYSYS
simulation file and GAMS input files for modeling the heat
integration.

The problem statement was posed by
Professor Costas D. Maranas and prepared by James E. Lease, Gregory L.
Moore, Ryan M. Scofield and Joseph D. Sevick in the department of
Chemical Engineering at the Pennsylvania State University. Mike Kalp
was also involved in putting the case study together, and he was
supported by the ECSEL program at Pennsylvania State University.

 

This case study is available in two forms:

  1. Hardcopy with binder and disk with HYSIS input file

          CACHE
Supporting department $50

         
Non-supporting department $90

    b. CD-ROM containing text of case study and
HYSIS file. Large flowsheet diagram is also provided.

        CACHE Supporting
department $30

        Non-supporting department
$50

 

CACHE Process Design Case Study
Vol. 8

“Nitrogen from Air” (on-line version available at no cost)

Nitrogen from Air

My design Group has just finished the development of a web-based case
study and tutorial entitled: Nitrogen from Air. This represents a
significant advance over the one developed previously. It includes
detailed process descriptions, downloadable reports and simulation
input files, and calculators and animations.

Larry T. Biegler, Carnegie Mellon University

 

CACHE Process Design Case Study
Vol. 9

“Conceptual Design of Second Generation Bioethanol Production via Gasification of Lignocellulosic Biomass”

This case study deals with the conceptual design of production processes for obtaining ethanol using switchgrass as raw material using the thermal route. The switchgrass is gasified with either low pressure indirect gasification or high pressure direct gasification to produce syngas. The resulting gas is reformed and cleaned up in a series of stages to remove solids and sour gases. In the next step, the syngas is used to obtain ethanol either via fermentation or by catalytic synthesis. Finally, the products are purified using different technologies for dehydration or ethanol recovery from a mix of alcohol. Two reports are presented from two groups of students. Based on the same initial information, the groups selected different flowsheets for the production of ethanol, the major difference being the choice of fermentation versus catalytic synthesis. The reports consist of three memos: literature survey and selection of initial flowsheet, mass and heat balances of selected flowsheet, and economic evaluation. Short-cut models are used and the reasons behind the selection among the alternatives and the results are discussed. Background material and teaching aids are also included.

 

CACHE Process Design Case Study
Vol. 10

“Conceptual Design of the Supply Chain and Production Facility of Lignocellulosic Bioethanol via Hydrolysis”

This case study deals with the conceptual design for the production of lignocellulosic ethanol via hydrolysis including plant location, selection of the field for growing the biomass, transportation and storage to supply 80MMgal/yr of bioethanol to Chicago and Pittsburgh. The switchgrass is to be pretreated to expose the polymers for hydrolysis obtaining the sugars. Next, the sugars are fermented to ethanol, and lignin is to be recovered. Finally, the products are purified using different technologies for dehydration of ethanol. Complete reports from two groups are presented. Each report consists of three memos: literature survey and selection of the plant location and initial flowsheet, mass and heat balances of selected flowsheet, and equipment sizing and economic evaluation. Reasons behind the selection among the design alternatives are discussed as well as the results that were obtained with short-cut models. Background material and teaching aids are also included.

 

CACHE Process Design Case Study
Vol. 11

“Conceptual Design of an Aromatics Plant from Shale Gas”

In this case study shale gas and condensates from the wet gas (e.g. ethane) are used as raw material instead of more expensive crude oil to produce aromatics (benzene, toluene, xylene). One of the interesting points in the case study is the number of different flowsheets that can be synthesized. Students must first screen different alternative chemical pathways based on methane and ethane to decide on the specific process. Furthermore, apart from the use of Mathcad or Excel for preliminary process calculations, process simulation using ASPEN-PLUS is used for the development of the detailed mass and energy balances of the plant, while ASPEN-ENERGY ANALYZER is used for energy integration and synthesis of heat exchanger networks. The case study contains detailed flowsheet designs from two design groups at Carnegie Mellon. The designs are documented through 3 memos that cover literature survey and preliminary screening, mass and energy balances and economic evaluation. Background and supporting material for the instructor is also included.

 

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