Interim Design Report for the Conditioning of Waste Oil from
French Fry Manufacturing for Use in Biodiesel Production
To: Don Sturtevant
Prepared by: French Fry Fuel
Team Members:
Marie E. Stark
Kate Burlingame
Shane Bird
John Neal
Charles Weatherspoon
December 11, 2007
ii
201 W. Lathen St. #8
Moscow, Idaho
(208) 407-4607
fffuel@uidaho.edu
Dec. 04, 2007
Don Sturtevant
Corporate Energy Manager
J.R. Simplot Company
One Capitol Center
999 Main street P.O. Box 27
Boise, ID 83707-0027
Dear Mr. Don Sturtevant:
Enclosed is a copy of “Interim Design Report for the Conditioning of Waste Oil from
French Fry Manufacturing for Use in Biodiesel Production.” This report summarizes the
teams’ research and design ideas completed in the first semester of our fall 2007 senior
design class. It will encompass the research, testing, and treatment processes of the
Simplot oil. Funding for our project was provided by Simplot with a budget of 10,000
dollars. Our report will be submitted to the University of Idaho Mechanical and
Biological Agricultural Engineering departments as a fulfillment of our mechanical
systems design class under Dr. Tom Hess and Dr. Steve Beyerlein.
This report includes information regarding the concepts of reducing waste oil free fatty
acids and processes used to remove water and other carbon impurities. After testing, our
team determined that the mainstream oil was suitable for conversion to biodiesel. We
then focused our attention on the dissolved air flotation (DAF) oil. This oil is a
combination of used fry oil and waste oil cleaned off the plant floor. We will recommend
evaporative water removal processes and esterification concepts to treat this waste oil.
We would like to thank you and Dr. Tom Hess for the assistance provided throughout the
design process. Additionally we would like thank Joe Thompson, Paul Mann, and Dr.
Van Gerpen for their help and consulting throughout the project. If you have any
questions or comments please feel free to contact us through the phone number and email
address stated above. We also recommend visiting our website:
http://seniordesign.engr.uidaho.edu/2007_2008/frenchfryfuel/. It contains the team
information, research, and process outlines.
Sincerely,
Team French Fry Fuel
iii
EXECUTIVE SUMMARY
This report provides the analysis and research of processes taken to condition waste
potato frying oil from Simplot. Particular emphasis was placed on the dissolved air
flotation (DAF) oil.
In the beginning of the semester the team’s goal was to condition the mainstream waste
oil from Simplot. The mainstream oil turned out to have 1.5% free fatty acid content and
<.1% by volume water content. Not much conditioning would be needed. Our attention
turned to the other waste oil stream called the DAF oil.
There are three major factors that must be addressed with our approach to condition the
DAF oil. First, the oil has particles much larger than the mainstream oil. A filtering
process must filter this oil to roughly 30 microns. Second, the DAF oil has a high free
fatty acid content making the oil harder to condition. Finally, the DAF oil is pumped with
water from the plant to a holding tank. Therefore the oil has a high water content that
needs to be removed.
Methods researched for water removal included two different types of evaporators called
flash and falling film. These are heat exchangers that evaporate the water in the oil using
a heat source. The evaporators used to remove the water are very costly and involve
multiple mechanical components. To reduce the free fatty acid content of the oil the team
proposes to use a process called acid esterification. For this process BD20 beads were
explored. The beads serve as catalyst and take the place of an acid in the esterification
process. Sulfuric acid is produced at Simplot and is being considered to be used as well.
Continuous paper filters were considered for removing the particles.
Our team is looking into the BD20 beads for the catalyst instead of the sulfuric acid.
Although, Simplot produces sulfuric acid, this can be a dangerous chemical around the
plant. The sulfuric acid may be cost efficient, but we recommend the use of beads since
they can treat high free fatty acid, while being safe around the food processing plant. The
team also recommends the use of the falling film evaporator for removing the high water
content, however this evaporator is very costly and other mechanical means of removing
water will be investigated.
iv
Table of Contents
1.0
2.0
3.0
4.0
4.1
4.2
4.3
5.0
6.0
6.1
6.2
6.3
7.0
Background .............................................................................................................. 5
Problem Definition................................................................................................... 5
Project Plan .............................................................................................................. 6
Concepts Considered ............................................................................................... 6
Particulate Removal System .................................................................................... 7
Water Reduction System.......................................................................................... 8
FFA Reduction System ............................................................................................ 9
Concept Selection .................................................................................................. 10
System Architecture ............................................................................................... 11
Particulate Removal System .................................................................................. 11
Water Reduction System........................................................................................ 11
FFA Reduction System .......................................................................................... 12
Future Work ........................................................................................................... 13
List of Figures
Figure 1: Integrated Solution .............................................................................................. 7
Figure 2: Bag Filter ............................................................................................................. 8
Figure 3: Self Cleaning Paper Filter ................................................................................... 8
Figure 4: Flash Evaporator.................................................................................................. 9
Figure 5: Falling Film Evaporator ...................................................................................... 9
Figure 6: System Design ................................................................................................... 10
List of Tables
Table 1: Project Parameters ................................................................................................ 5
Table 2: Semester 1 Team Progress .................................................................................... 6
5
1.0
Background
The J.R. Simplot Company is one of the largest privately held firms in the country,
employing approximately 10,000 people worldwide. As a large
agribusiness firm, Simplot has significant fuel costs associated with their transportation
fleet. As a means to reduce this cost, Simplot would like to
use the waste oil generated in the Simplot French Fry Plant located in Caldwell, Idaho to
manufacture biodiesel. Currently Simplot sells this waste oil as cattle feedstock or
disposes of it as waste; however, the rising price of gas makes converting the oil to
biodiesel a financially favorable option for Simplot.
2.0
Problem Definition
The waste oil from Simplot’s production lines forms three waste streams. The largest of
these streams has been tested and determined to be suitable for conversion to biodiesel.
The other two streams, which constitute oil recovered in plant cleanup (MOP) and oil that
passes through the wet electrostatic precipitator (WESP) currently conjoin and are
transported to a dissolved air flotation (DAF) tank. The goal of this project is to examine
the MOP and WESP oils and determine a treatment plan to condition the oil. The team
will design a system to remove free fatty acids (FFA), water, particulates, and other
carbon impurities from the used oil to a specification defined by the biodiesel
manufacturer. A cost estimate of full scale production will be provided for the design
selected. In addition to these client needs, a smaller “bench top” model will be designed
and constructed for presentation in late April. A detailed list of these needs can be found
in the following table.
Table 1: Project Parameters
User Need
Remove Impurities
Small bench Top Design
Bench Top within Budget
Cost Estimate for Full Scale
Specification
Reduce Free Fatty Acid
Concentration
Reduce Water Content
Remove Impurities
System must fit in booth at
Engineering Expo
Cost analysis of system
Cost analysis of system
Target Value
<4% by weight
<.1% by volume
<50-100μm
<Standard Banquet Table
Size
Within budget
Dollars per gallon
6
3.0 Project Plan
The system required to pretreat Simplot’s oil is a complex one. In order to understand this
process, Team FFF has consulted many experts in the field, including Dr. Jon Van
Gerpen, head of the biological and agricultural engineering department, Scott Burn, a
consultant in the field, Joe Thompson, a biodiesel expert on the University of Idaho
campus, and Paul Mann, a consultant. Working in Joe Thompson’s biodiesel lab, the
team has tested FFA concentration and water concentration on the mainstream oil. After
testing the oil, the team converted it to biodiesel in the lab. Additionally, a thorough
literature review was conducted to review current technologies available. A summary of
the team’s progress to date can be found in the figure below.
Table 2: Semester 1 Team Progress
% Complete
100%
100%
75%
100%
100%
100%
100%
100%
100%
100%
100%
100%
100%
90%
4.0
Task
Gather Information on biodiesel and
establish specifications
Visit Simplot French Fry Plant
Owner
All
Deadline
9-10/2007
All
10/1/2007
Create project specs and list of needs
Get in contact with Joe Thompson and
perform research on oil samples
Contact Van Gerpen and discuss options
with him
Brainstorm 2 design concepts for each
design parameter
Research 2 filter systems
Research Sulfuric Acid
Research BD20 Beads
Research Flash Evaporators
Research Falling Film Evaporators
Snapshot Day
Design Review
Final Interim Report Due
All
All
10/10/2007
10/15/2007
All
11/14/2007
All
11/5/2007
Chuck
Marie
Kate
Shane
John
All
All
All
11/9/2007
11/9/2007
11/9/2007
11/9/2007
11/9/2007
11/30/2007
11/30/2007
12/11/2007
Concepts Considered
For the concept generation phase, Team FFF initially tested, analyzed, and constructed a
design that would condition the mainstream frying oil. After lab analysis, the mainstream
oil was determined to be acceptable for the conversion into biodiesel. From this point
Team FFF, under the client’s direction, diverted their efforts towards the conditioning of
the DAF oil.
7
Team FFF developed two concept solutions for each of the three design parameters to
treat the DAF oil. These concept solutions are summarized in the following pages. The
ideas developed for the three design parameters can be integrated into the final design.
Our scope did not allow for complete prototype assembly and testing. Figure 1 below
shows the current integrated solution create by Team FFF.
Figure 1: Integrated Solution
4.1 Particulate Removal System
The oil collected from the cleanup of the plant is full of charred bits of potato and carbon
impurities. These particles inhibit the production of biodiesel from the oil. The particles
clog machinery at the biodiesel plant and will damage an engine running the bio diesel.
A filtration system is needed in the pretreatment design to lower the level of particles.
The first system that was considered to handle this need is an inline bag filter. This
system pressurizes the oil and pushes it through a sock filter. Particles above a certain
size will be filtered out. However, because the sock filter is made from felt with a weave
knit pattern some particles may still be able to push through. An inline bag filter system
is simple and cheap when compared to the other option considered. The sock filter would
require continuous replacement to prevent clogging that would stop the flow of oil
through the system. This would add an additional maintenance and labor cost.
8
Figure 2: Bag Filter
The second solution concept is a self-cleaning continuous paper filter system. This
system pushes the oil through the filter paper by gravity. The oil passes through the
paper into a collection basin while the particles are retained on the surface of the paper.
The paper continuously rotates across the basin, removing all particles. This is a low
maintenance system. However, the paper roll still needs to be replaced eventually. A
major concern about this system is that it has a high initial cost.
Figure 3: Self Cleaning Paper Filter
4.2 Water Reduction System
Water removal is a large concern in the production of biodiesel. Water can oxidize the
oil thus creating free fatty acid. Also, if there is water in the system when oil goes
through the biodiesel processing it creates soap as a byproduct. This lowers the total
yield of the oil. The water also hinders the esterification process if used in the
pretreatment process.
There are two systems that are currently being considered for drying the oil. The first is a
vacuum flash evaporator. This system heats the oil and pumps it through a nozzle into a
vacuum tank. This flashes off high levels of water from the oil. This system can only
9
handle oil up to 5% water by volume. Any higher level of water will require more flash
evaporators. When compared to the other system considered, the flash evaporator is
cheaper and simpler to design.
Figure 4: Flash Evaporator
The second system considered to dry the oil is a falling film evaporator. This system is a
tube in shell heat exchanger that has the oil fall down on the tubes as a thin film. The
tubes are heated with steam, which then heats the oil to evaporate the water. The water
vapor is then pumped out and condensed. This system requires a high level of design and
thus makes the system more costly. However, this system can handle higher levels of
water than the flash evaporator.
Figure 5: Falling Film Evaporator
4.3 FFA Reduction System
FFA formation typically occurs when the oil has been stored for an extended period of
time and water has been allowed to stay in the oil. FFAs are formed in oils from the
process of water molecules hydrolyzing fats. It is extremely important for the production
of biodiesel to reduce the amount of FFA in the oil. The purpose of reducing FFA is that
the formation of soaps may occur at high levels of FFA during the transesterification
process. Soaps inhibit the complete formation of biodiesel and result in a lower yield of
fuel. Chemical processes, such as esterification, may reduce the content of FFA, where
upon shipment to the biodiesel facility, transesterification may then be implemented to
convert the FFA to biodiesel.
Team FFF designed two concept solutions to help reduce the amount of FFA in the oil.
The first concept solution utilizes an existing method of esterification most commonly
used in biodiesel production. This acid catalyzed reaction uses sulfuric acid as a catalyst.
The sulfuric acid is dissolved in methanol before reaction with the oil. An important and
inhibiting problem associated with using sulfuric acid is the oil needs to be completely
dried as the reaction takes place, due to the properties of water reducing the formation of
biodiesel. Using sulfuric acid reports a high rate of biodiesel conversion. The acid is a
byproduct from another system process Simplot has invested in, so cost of using the acid
is a low consideration.
The second concept considered uses a newly introduced product called Amberlyst BD20
beads. These beads are another solution to acid esterification with out the hazardous
protocols needed when using sulfuric acid. The beads are used in a filter-like system
where the oil may wash through and react with the chemical beads, thus lowering the
FFA content. The beads have increased attributes to the conversion of higher quality oil.
10
They allow the oil to have a FFA content ranging from 0.5- 100% and have high
conversion reaction times, as well as fewer toxic chemicals. Based on these
characteristics, the problem associated with the use of the beads involves cost (the
product is new to the market) and what cost savings the beads may have compared to
sulfuric acid.
5.0 Concept Selection
The selection process involved evaluating the strengths and weaknesses of each of the
two concept solution considerations for the three design parameters. After initial concept
generation Team FFF presented our progress to a board of peers, the team professor, and
clients in a conceptual design review on Friday, November 30th 2007. The goal of the
review was to obtain explicit direction for the project for the semester ahead. We wanted
to identify which processes or mechanisms the client would like to pursue and which
concept designs to further investigate.
The best component of each of the three design parameters was selected and integrated
into one design concept (see Figure 6 below).
Figure 5: System Design
The two filter systems were discussed including the request of exact price estimates for
the currently in-use paper filter system as well as the low cost and easy to use bag filter
system. The criteria for determining the filter system had not been previously identified.
After discussion with our client, we are open to further design considerations and will
provide cost estimates for both filtering systems. The FFA reduction system was
developed by either selecting sulfuric acid for the acid-catalyzed FFA esterification
process or using a newly developed product, BD20 beads that use the same principles as
acid esterification. It was determined to request samples of the BD20 beads from the
manufacturer and test the new product and determine if the beads were an economically
viable option compared to using the readily available, yet hazardous, sulfuric acid. Next,
the two processes for water removal were discussed. A falling film evaporator and a
flash evaporator system were analyzed and compared. In order to further identify which
system, for each process, to implement into the design, an accurate price of both sulfuric
acid and natural gas that is currently being used on site is needed. In addition, further
characterization of the MOP and WESP oils must be achieved.
An initial concern involving the use of WESP, MOP and DAF oil was if these oils would
be at compliance level regarding water and FFA content if the particulate matter was
removed. We were given samples of these oils to further test and determine if the MOP
oil, in particular, may be recovered before being combined with the WESP oil. Our client
11
and advisors expressed their general interest in evaluating all design considerations on a
cost effective basis.
If we want to exceed our client’s expectations, then we need to look at the whole process
and develop every step, from particulate removal to water and FFA reduction to meet
their standards for biodiesel production and keep a cost effective analysis in mind. The
following discussion will develop a conceptual design case for each integrated design and
its individual parameters, showing how the overall design will exceed customer
expectations.
6.0
System Architecture
6.1 Particulate Removal System
A 50 micron felt filter bag may be used to filter particulates from waste streams.
McMaster-Carr provides 50 micron polypropylene felt bags that withstand a maximum
temperature of 300°F. They also provide 50 micron nomex felt bags that withstand a
maximum temperature of 400°F. McMaster-Carr also provides stainless steel filterbag/cartridge housings that are rated for 300 and 400°F operational temperatures [1].
http://www.mcmaster.com/ The fluids that are filtered through the bag and bag housing
will not be above 400°F because this is close to the flash point of the oil. The type of
filter bag and housing used in our system will depend on the temperatures of the fluids
that are filtered through them. The lower rated temperature bags and housings cost less
than the higher temperature bags and housings. Filter bags are sized with a maximum
flow in gallons per minute. The filter bags that are sold by McMaster-Carr are rated from
a range of max flows between 20 and 275 gallons per minute.
An alternative to the bag filtration system is a continuous paper filter. Disposable paper
continuously passes through the system and removes particulates from the oil. Simplot in
Caldwell, Idaho currently uses two continuous paper filters on their production lines.
The oil is gravity fed into this system so there will not be continuous pressure in the oil
filtration system. The only maintenance needed for this system is changing the paper
roll. Heat and Control sells these filters[2]. www.heatandcontrol.com This type of filter
might be more than is truly needed for our system because it is used to remove ultra-fine
particulates and we need to only remove 50 to 100 micron sized particulates because the
biodiesel manufacturer has filters that remove particulates up to biodiesel specification
requirements.
6.2 Water Reduction System
Our current water content specification requirement is less than .1% by volume. The
biodiesel manufacturing company does not have a permit for handling water from a waste
stream so this specification must be met at Simplot before the oil is transported to Blue
12
Sky. Simplot currently has a DAF system that skims the oil off the top of the water in a
large tank. We received a sample of this oil and are in the process of testing the water
content.
We have researched two types of water removal methods that may be used after the oil
comes out from the DAF system. One system is a flash evaporation system. This system
requires a vacuum pump, nozzle, and a system for heating the oil and water above the
water vaporization temperature. The oil and water are heated with steam in a shell and
tube heat exchangers. Currently flash evaporators are designed to remove water content
up to 5%. If the water content is higher than 5%, a series of flash evaporators may be
used to remove the water. Another system that may be used to remove water content
above 5% is a falling film evaporator. A falling film evaporator consists of a large heat
exchanger. This heat exchanger is heated by steam.
We have recently received a sample of oil that was collected upstream from the DAF
tank at the WESP. This oil separated from the water after it settled. We have found out
that it is beneficial to remove the oil from the WESP upstream before it mixes with the
oil from the MOP. An option for initially removing large quantities of water from this oil
is by using a settling tank with a skimmer on the top that is similar to the DAF system.
Further research needs to be done on this type of a system.
6.3 FFA Reduction System
As previously stated, two methods for reduction of the FFA content were developed.
After preliminary research, acid esterification using Amberlyst BD20 beads is the
recommended process. Although these processes produce similar results, the BD20 beads
allow for an easier system design. The beads can be used to treat varying levels of FFA
concentrations; the oil is simply processed more slowly through the standing column of
beads for higher FFA concentrations. This allows for a longer reaction time.
Additionally, because the beads are hydrophobic they repel up to 5% water at the reaction
sites. This eliminates the need for continuous drying, which is required in esterification
using sulfuric acid as the catalyst because the water that is generated in the reaction will
act as a limiting agent.
BD20 beads are not hazardous. The Rohm and Haas website, the manufacturer of the
Amberlyst beads, states that similar ion exchange beads are disposed of by land filling or
incineration. Reducing the cost of waste disposal associated with toxic compounds such
as sulfuric acid may offset the potentially higher price of the beads. Furthermore, using
the beads as a catalyst eliminates the risk of accidental workplace injuries, accidents, and
food contamination.
More research is needed to determine if the BD20 beads are a financially viable option
for this design. Because the beads are an emerging technology there is not currently any
information on the price of the beads.
13
7.0
Future Work
.
Testing of the DAF oil is the first step for our project continuation. The tests for FFA
and water content will determine what type of processes we will implement. If the water
content is high, then the falling film evaporator will have to be used instead of the flash.
For the heating element in the evaporators, natural gas costs will need to be researched.
The price of the BD20 beads will decide whether or not we want to use them in place of
the sulfuric acid in the esterification process. Prices of filters used at Simplot need to be
compared to other filters to see if one is more cost effective than the other.
Our client requested that we look into other mechanical means of removing the water
from the DAF oil. For example, a heated agitated tank may be a simpler and much more
cost effective way of removing the water. This would also allow easier modeling for the
bench scale required at the end of the next semester. The bench scale model will be an
important deliverable and must be the focus of next semester. Flow rates, temperatures,
costs, and other characteristics of the system will need to be accurately modeled in the
bench scale, and then scaled up appropriately for the client and plant operation.