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Chemical Engineering Cohort
Production of Power Ethanol from Corn
Background
Ethanol produced via biochemical processing routes has been used as a road transportation fuel for
many years in arts of South America. It has also been used as a fuel blend in parts of the USA and
Europe. Fuels produced by biochemical means serve to reduce our reliance upon fossil resources
and make a contribution to the transition to net zero.
Design Basis
Feed Composition
The corn composition is as shown in Table 1.
Table 1: as-received corn composition
Component
Mass Fraction
Starch
0.61
Fibre
0.13
Water
0.14
Protein
Lipids
0.08
0.04
Process Description
The process to convert corn into bioethanol is described in the following text which is based on the
paper by Kwiatkowski et al. [Ind. Crop. Prod., 23, (2006) 288-296]. It is recommended that you read
this paper, and other similar papers/books in the literature as necessary, to familiarise yourself with
the process. The process is summarised as follows:
•
•
•
Storage, conveying and grinding. The corn, which is transported to the plant from the
fields, is stored in silos. It is then conveyed to the grinding equipment where it is ground to
the desired particle size.
Liquefaction. The ground corn is heated to 95 °C to make the starch available for the
subsequent stages.
Saccharification. In this stage the enzyme, glucoamylase, is added to convert the starch to
glucose via the following stoichiometry.
C6H1005 + H2O → C6H12O6
.
Fermentation. Glucose is converted to ethanol by the yeast Saccharomyces cerevisiae. The
vapour phase from the fermentation reactor is scrubbed to minimise any ethanol losses.
The stoichiometry for the fermentation is as follows in which C5H702N is the empirical
formula of the microorganisms.
->
C6H12O6 +0.16NH3 → 0.16C5H702N + 1.73C2H60+ 1.73C02 +0.49H₂O
• Distillation. Distillation is carried out to separate ethanol from water and achieve a
composition closer to the azeotrope.
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2023/24
•
Purification. Purification increases the ethanol purity to the required specification. Assume
that purification is carried out by extractive distillation.
• Stillage evaporation and drying. Stillage is the stream that contains all the organics in the
corn which are not starch and the microorganisms produced in the fermentation. Stillage is
subject to centrifugation, evaporation and drying and then sold as animal feed.
Temperature Data and Utility Constraints •
•
Purification. Purification increases the ethanol purity to the required specification. Assume
that purification is carried out by extractive distillation.
Stillage evaporation and drying. Stillage is the stream that contains all the organics in the
corn which are not starch and the microorganisms produced in the fermentation. Stillage is
subject to centrifugation, evaporation and drying and then sold as animal feed.
Temperature Data and Utility Constraints
Compressors should not be specified with an outlet temperature in excess of 150 °C;
The ambient air temperature will vary from -10°C to 30°C throughout the year;
• Natural gas is available at 30.0 bara;
• Electricity is available from the grid.
Plant and Equipment
• Initial assumption of 0.5 bar pressure drop across heaters, coolers and heat exchangers;
• Pumps and compressors operate with 75 % adiabatic efficiency.
Product Specification
•
140000 te/yr of fuel-grade ethanol (≥99.0 wt%) are required.
• Plant should be designed to operate for 8000 hr/yr.
Upstream Oil and Gas Production Process Design & Simulation
Your final design report should include;
Communication of Design Basis by standard Design Basis form
• Carbon emissions statement
•
Material and energy balance communicated by PFD(s), stream table(s), equipment list(s) and
footprints;
о Work package 1 - Liquefaction
о Work Package 2 - Saccharification
о Work package 3 - Fermentation
о
Work package 4 - Separation
о
Work package 5 - Purification
•
•
о Work package 6 - Provision of Power and Heat Integration
Work package 7 - Process Heating and Cooling
Report from each engineer on the decision making, analyses and optimisation(s) which led
to the final design;
Equipment sizing/specification/design for all work packages;
• Process Control, Process Safety & LOPA for all work packages;
•
Decisions documented and design summarised by PID
Hazards and Operability (HAZOP) Study for all groups (counts towards 2.5% of Group Report
Mark)
• Log of minutes of meetings
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Ethics, Environment & Sustainability
Individual supplementary report: 7.5% of Group Report Mark
The client for whom we are undertaking the design has requested that we deliver
2023/24 Ethics, Environment & Sustainability
Individual supplementary report: 7.5% of Group Report Mark
The client for whom we are undertaking the design has requested that we deliver
comment/analysis/proposals on the following issues;
1. Ethics (1.5%). Whilst it has been noted that the initial economics show the process to be
viable, it has been suggested that the company considers the wider reputational impact of
this process in the context of the food vs. fuel debate. Should the company engage in this
project or should we waive the opportunity and publicise a position of not using food to
produce transportation fuel?
2. Environment & Sustainability - Process (3%). The client has an interest in investigating new
and emerging technologies which may make running the production process more
environmentally friendly and more sustainable.
3. Environment & Sustainability - Operations (3%). The client has an interest in making day-
to-day plant activities more environmentally friendly and more sustainable.
Project Management
Groups should establish how they are going to work together on the joint tasks to best achieve the
outcomes in the time available.
Formal minutes should be taken for group meetings and include, at the very least:
• Meeting date, time and location
•
Those present
Those who gave apologies
•
Those who were not present and gave no apologies
•
Report on agreed actions from previous meeting
•
Statement of agreed actions from meeting
Deliverables
The deliverables are described in detail in the course documentation. In summary;
1. Group design report with individual contributions clearly marked.
At the very minimum, all reports should contain demonstration of a converged material and
energy balance via PFD(s), stream table(s) and equipment list(s), PID(s) with main basic
process control loops and process equipment design data sheets.
2. Group Oral Presentation of Design
The deadline for all material is as set by Dr Nikora for EG4578. See course documentation for full
details.