automationbiodieselprocessor-elsawy-022812

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AC 2012-3262: AUTOMATION OF A BIODIESEL PROCESSOR FROMWASTE VEGETABLE OIL USING PROGRAMMABLE LOGIC CONTROLLE

Dr. Ahmed H. ElSawy, Tennessee Technological University

Dr. Ahmed ElSawy joined Tennessee Technological University (TTU) as a professor and Chairperson,

Department of Manufacturing and Industrial Technology, in July 1, 1999. He holds B.Sc., M.Sc., and

Ph.D. degrees in mechanical engineering with an emphasis on materials processing and manufacturing

engineering. Prior joining TTU, ElSawy held several industrial and academic positions in the USA and

abroad. ElSawy teaching and research interests are in the areas of material processing, metallurgy, and

manufacturing systems. ElSawy received approx. $2 million of state, federal, and industrial grants in

support of his laboratory development and research activities. He advised several masters and doctoral

students who are holding academic and industrial positions in the USA, Germany and Taiwan. ElSawy

has numerous publications in national and international conferences and refereed journals.

Dr. George M. Graham P.E., Tennessee Technological University

George Graham is the Director of the Wacker Institute and Department Head of Chemical, Manufactur-

ing, and Industrial & Systems Engineering Technology at Chattanooga State Community College. He

was previously an Assistant Professor in the Department of Manufacturing and Industrial Technology atTennessee Technological University. Prior to his academic appointment, he held Director, Manager, engi-

neering, and research positions in automotive manufacturing and construction industries. He is a member

of the American Society of Mechanical Engineers, American Society for Engineering Education, and the

Association of Technology, Management, and Applied Engineering. He teaches courses in manufacturing,

welding, controls, and automation.

cAmerican Society for Engineering Education, 2012


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Automation of a Biodiesel Processor from Waste Vegetable Oil Using

Programmable Logic Controller

Ahmed ElSawy* and Michael Baswell***Professor and Chairperson of Manufacturing and Industrial Technology and **Assistant

Professor of Electrical Engineering, College of Engineering,Tennessee Technological University, Cookeville, Tennessee 38505-0001, USA

Abstract

There is a strong need in the USA to decrease dependency on fossil fuels and implement asustainable energy policy. Many efforts are underway to power vehicles and equipment withalternative energy sources. One alternative fuel that has gained much popularity in the past fewyears is biodiesel. Biodiesel can be produced using virgin vegetable oil or waste vegetable oil(WVO) as the raw material. WVO is readily available and typically inexpensive; however the process to convert WVO into usable biodiesel is time consuming, requires a human operator to

run the system, and necessitates a human to perform a chemical titration for each batch of biodiesel produced. Due to these requirements, a typical biodiesel processor requires muchoperator interaction which has not yet been eliminated by existing ―automated‖ systems.

Groups of senior design students were engaged in the design, production, and testing of anautomated biodiesel processor. The source of the WVO for this project is the university’s foodservices and other nearby businesses. By converting this WVO to fuel for power generation, theoverall waste generated by the campus will be reduced and have a positive environmentalimpact. The output of the process is certifiable B100 biodiesel.

In the first phase of this project, the processor was designed and built by the studentsutilizing a programmable logic controller (PLC) in conjunction with pumps, valves, temperaturesensors, etc., to completely handle the production of biodiesel with minimum operatorinteraction. The system eliminates the need for the titration process, circulates the fluid thoroughthe system, and upon completion of a full cycle, the end user is presented with a certified biodiesel. This paper presents the first phase of this project and demonstrates the design and process used to automate biodiesel production using a PLC and how the chemical titration procedure for each batch is eliminated.

Keywords — Biodiesel, Waste Vegetable Oil, Chemistry, Alternative Energy, Programmable

Logic Controllers.

Introduction

With our desire to recycle and reuse solid waste, many people are looking for alternativeways to power vehicles and equipment using biofuel. However, many people are still hesitantabout turning away from internal combustion engines. One alternative fuel for diesel engines is biodiesel which gained popularity in the last few years. The primary ingredient, waste vegetableoil (WVO), is readily available and relatively inexpensive. However, the current biodiesel

processors available to produce a batch of biodiesel are time consuming. They require anoperator to run and monitor the system, and necessitate a chemical titration procedure for each


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batch to be produced. A typical batch processor requires much operator interaction, and even theexisting ―automated‖ ones require some interaction. In order to reduce the time, a moreadvanced system is needed. Therefore, the main objective of this project is to explore potential alternatives to the current biodiesel production methods, thus contributing to

biodiesel commercialization. This project is an attempt to reduce the operator interaction of

depositing waste vegetable oil into the processor and as well eliminating the titration process,moving the fluid throughout the system, and presenting the end user with biodiesel upon

completion of a full cycle.

Motivations

There are four broad areas in which the production of biodiesel on-campus could make a difference:1) Education; 2) Environment; 3) Awareness; and 4) Economics. Even though the economics will notlead to large profit for the university, the beneficial impacts of biodiesel production in the areas ofeducation, the environment, and sustainable publicity make this project worthwhile.

1) Education: The entire process of converting WVO to biodiesel can serve as an experientiallearning experience for students at TTU and community members in the local Cookeville and UpperCumberland areas. The processor and its inputs and outputs can be studied and modeled using

simulation packages. This study could take the form of a lab project or a lecture problem set for

chemistry, engineering, and technology students. The process could be studied as a simple logistics problem for entrepreneurship and small business classes, possibly with the economics of the production used as a case study.

2) Environment: Approximately 5,000 gallons of petrodiesel could be displaced by biodiesel derivedfrom WVO, with possibilities of expanding this volume to 6,360 gallons in the future. Biodieselhas environmental benefits, especially when considered on a life cycle basis.

3) Awareness: Putting the biodiesel processor on TTU's campus is a way to start showing the local,

national, and international community how TTU is starting to "walk the talk" in making its campus more sustainable.

4) Economics: Again, at this point student labor will be voluntary. However, the cost estimate to produce the biodiesel including student labor is estimated at $1.33/gallon while the petro-dieselcurrently costs approximately $3.95/gallon at the pump, a difference of about $2.62/gallon. This price is on the rise and it is expected to reach about $5.00 this summer.

Objectives

The ultimate goal of this project is to design, manufacture and test a continuous flow biodiesel processor. Therefore, this project is divided into two phases:

1)

In the first phase, the students are required to design, manufacture and test an automated

continuous flow system that will limit the operator interaction to deposit waste vegetable

oil into the processor. The system should automatically take care of moving fluids

throughout the system, all chemical reactions, draining of waste glycerol byproduct, and upon

completion of a full cycle the system should present the operator with finished


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biodiesel that meets ASTM standards. This system will make it easy to produce

sufficient amounts of biodiesel which can be used to fuel more diesel engines. The

specifications set for the current project’s processor are as follows: 1) Process given amount

of waste vegetable oil into quality biodiesel (ph between 7 and 7.25), 2) Minimal operator

input, 3) Minimal long term maintenance cost, 4) System must be expandable to

accommodate changes in operators needs, and 5) Plug into a standard 115 V electricoutlet. This phase is completed and the results are presented in this conference.

2) In the second phase of this project, the students will further develop the current system by using a novel continuous biodiesel processing technology. This technology creates a newquantum mechanical effect by drastically increasing the surface area-to-volume ratios. Theviolent reaction in the flow cell creates nano-sized bubbles that vastly increase surface areaon which reaction can take place. This technology can reduce the processing time from 1-4hours needed in batch processing to less than 30 seconds. Also, it reduces separation timefrom 10 hours, down to 1 hour. The ultimate goal of this project is to significantly increasethe production capacity and product quality while reducing cost. This phase is in progress

and the results will be presented in a future conference.Biodiesel Chemistry

Biodiesel is an alternative fuel derived from a renewable domestic resource. It has severaladvantages such as: 1) being biodegradable, 2) being non-toxic, 3) having low emissions ofcarbon monoxide, 4) having a relatively high flash point (150° C), which makes it less volatileand safer to transport handle than petro-diesel, and 5) it has a good lubricating properties that canreduce engine wear and extend engine life. The transesterification is the most common wayto produce biodiesel. It is a catalyzed chemical reaction involving vegetable oil and an

alcohol to yield fatty acid alkyl esters (i.e., biodiesel) and glycerol (Fig. 1).

Fig. 1 - A schematic representation of the transesterification of triglycerides (vegetable

oil) with methanol to produce fatty acid methyl esters (biodiesel) (6)


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The Triglycerides are the main component of vegetable oil. It consists of three longchain fatty acids esterified to a glycerol backbone. When the triglycerides react with

alcohol (methanol or ethanol), the three fatty acid chains are released from the glycerolskeleton and combine with the alcohol to produce fatty acid methyl esters (biodiesel) and

glycerol as the by-product. R1, R2, and R3 represent Alkyl groups present in the WVO. The

catalyst is NaOH (lye). In general, a large excess of methanol is used to shift theequilibrium far to the right (Fig.1).

The biodiesel making process is based upon a chemical reaction. A lipid transesterification process is used to convert waste vegetable oil (WVO) to a series of Fatty Acid Methyl Estersusing sodium hydroxide (lye) as a catalyst and methanol (99% + purity) as the primary reactant.In this work, methanol was used because it is less expensive than other higher molecular weightalcohols (such as ethanol), and the reaction is of higher quality. The major drawback of using alower weight alcohol like methanol is the cold filter plugging point is higher (meaning fuelgelling can occur at warmer temperatures), however in the southeast USA region this is not amajor issue. Excess free fatty acids that are in the oil are converted to glycerin, and after the

biodiesel is allowed to settle the glycerin can be drained off. In essence the goal of the reactionis to replace the glycerin molecule in the WVO with an alcohol molecule.

Automated Biodiesel Processor Description

1- Elimination of the Titration Process

In order to fully automate the process, the first step is the elimination of the titration processwhich is needed before Transesterification. This is because each batch of oil has a slightlydifferent composition. The titration process consists of take a small sample of WVO, and mixingit with lye, water and alcohol in order to determine the pH level of a sample from each batch of

oil and determining the correct lye to methanol ratio that is required for a particular batch. The process itself is not that difficult, but it does require careful measurement and operatorknowledge of the process.

To eliminate this procedure, a certain volume of WVO, a given volume of CH_3OH(methanol) and a given weight of NaOH (lye) are combined to produce sodium methoxidewhich will be used for the transesterification reaction. To obtain the needed amounts, a 25%the oil volume of methanol was used, and for lye 6.25 grams/liter of oil was used. Typicallywhen an operator performs the titration process on a batch, the batch requires between six andseven grams of lye per liter of oil (4). If fully reacted using 6.7 gallons of methanol and a potassiumhydroxide catalyst, 55 gallons of UVO will produce 4.3 gallons ofglycerin and 57 gallons of pure

biodiesel.

The Transesterification process chosen for this project consists of three steps to eliminatethe titration from the process. It is based on the fact that most oils have a similar composition and

therefore standard amounts of chemicals per volume of oil can be used. Additionally, this

method has the benefit of more completely reacting the oil with the sodium methoxide and

therefore producing more biodiesel than other methods. When the oil reacts all at once it willreach an equilibrium stage at which point the reaction completely stops, even though more

glycerin could be removed from the oil. Reacting the oil in two steps restarts the reaction at the


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second stage, allowing more glycerin to be split out of the waste vegetable oil. However, a

drawback to this method is an increase in processing time. For this project this is

acceptable as the length of the process is not a critical factor.

2- Biodiesel Processor

Fig. 2 illustrates the back side of the automated biodiesel processor. Before the actualreaction begins, it is important to preheat the WVO to reduce the viscosity and evaporate anywater existing in the oil from cooking. The next step is to pre-filter the WVO in order to removeany food particles remaining in the oil so that the oil is clean and ready for the chemicalreactions. To achieve this step, the WVO was poured through a series of progressively finerfiltering screens. The finest filtering screen should be around 50 to 75 microns. After the prefiltering stage, the oil is ready to be added to the 60-gallon tank for processing.

Fig. 2 – Illustrates the back side of the automated biodiesel reactor and its components Biodiesel Filtration and Soap/Glycerol Removal

In the 20 gallon chemical tank, the methanol and lye were mixed to produce the sodium

methoxide. This reaction is exothermic, which produces heat, and results in the formation ofsodium methoxide. Operators should avoid standing over the tanks from this point on as anyvapors released can be harmful or fatal. In the first step, the sodium methoxide is added to theWVO in two stages. First, the oil is reheated between 118o - 126°F (120°F is optimum) and 75%of the sodium methoxide is added. The mixture is maintained at this temperature and mixed forone hour using a circulating pump. Then the mixture is allowed to cool to room temperature andsettle for approximately 12 hours. Afterwards the glycerin was separated and settled into the bottom of the conical 60-gallon reactor tank and is drained off. In the second stage, the


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remaining 25% of sodium methoxide was added to the reheated oil to an average temperature of120o F, allowed to circulate/mix for another one hour, and then is allowed to cool for another 12hours before draining any final glycerin that formed (4).

The final step in the biodiesel process is to remove any soap, water, methanol, and other

contaminants from biodiesel that were inadvertently created during the processing. Traditionally,a wet wash system is used for this process. It requires several wash cycles with water, and eachcycle requires 12+ hours of settling/separation time. Then, it is also common practice to test the pH of the resulting biodiesel, and add an acid, such as vinegar, as necessary to balance the biodiesel’s pH level (4). Then the contaminated water must be properly disposed of, adding costand time to the process.

In this project, a drywash tower was designed specifically for this purpose (Fig. 2.) Initiallythe cost is greater, but the return on investment will be much higher because biodiesel can be produced faster and the end product will be of higher quality. Using a dry wash system with ionexchange media keeps us from having to balance the biodiesel pH by adding in an acid. In this

project, a two step dry wash process with Purolite® PD 206 filtering media (3) was planned.Before removing biodiesel from the 60-gallon reactor, it must be, or very close to, roomtemperature. This is because the higher temperatures can damage the filtering media andaccelerate the degradation of the PVC pipe. The biodiesel was pumped through the tower at arate of 7 gallons per hour. It was planned to have two dry wash filtration towers in order toensure that the maximum amounts of contaminants are removed in a shorter period of time. Thefirst tower is known as the lead tower and the second is known as the lag tower. From the drytowers, the biodiesel is pumped into a holding air tight and sealed tank, where it is ready to usein virtually any diesel engine.

Figure 2 shows the drywash filtration towers designed for this purpose. Drywash towers were built from inexpensive 4-inch diameter PVC pipes. Once the drywash media is in the tower, theoperator needs to allow up to 150% expansion of the media, or maximum fill point should only be 40-45% of the tower. Because this process is not using a methanol removal step, thePurolite® will not last as long as. Typically, one pound of Purolite® can be used to filter 1500-2000 pounds of biodiesel (200-275 gallons). Because this process does not use a pre-methanolrecovery system, it is estimated that the Purolite®’s useful life is half of what is normallyexpected (this applies to the lead tower only). For the lag tower, the operator can monitor thecondition of the fuel exiting, and once signs of impurities are noticed the media should beremoved. Purolite® can be regenerated (i.e. cleaned) by soaking in methanol (7). Afterregeneration, the ―dirty‖ methanol can be re-used as a reactant. However, it should not be usedin greater concentrations than 50% re-used methanol to unused methanol.

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Programmable Logic Controller Programming

The last step involved is writing a PLC program to control the two phase process andincorporate the drywash towers. The current biodiesel processor uses an Allen Bradley 503 PLCcontroller. The AB-503 PLC controller was selected because it is currently widely used inindustry. It has multiple input and output capabilities and is easy to program (Fig. 3). Inaddition, the PLC will allow the operator to add a vast array of items to the process, such as flow


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meters, temperature gauges, timers, solenoid valves, and pumps quite easily. The processorworks on an input/output basis for each action to occur. Once an input signal/signals arereceived (a given temperature, elapsed time, etc.) the controller sends an output signal (beginmixing, turn heater on, etc.).

The PLC controller has 16 inputs (I:0 – I:15) and 8 outputs (O:0 – O:7) (Fig. 4). Oneimportant thing to note is a switch which hangs down below the PLC panel. This switch must bedepressed for the 1‖ NC 12 volt DC solenoid valves to work (4). There are three buttons on thePLC panel; a green start button, a red stop button, and a clear green reset button. The red stop button can be pressed at any time to stop the processor. The reset button can also be used to stopthe program, and it must be pressed after the stop button is pressed in order to reset the countersin the program.

Fig. 3 – Illustrates the 503 Allen Bradley controller

Inputs

I:1/0 ThermostatI:1/1 Fluid Level Sensor 1 (Bottom of Small Tank)I:1/2 Fluid Level Sensor 2 (Top of Large Tank)I:1/3 Fluid Level Sensor 3 (Bottom of Large Tank)I:1/4 Stop Button (Red)I:1/5 Start Button (Green, bottom button) (NOTE: Press to start 1st and 2n phase.)I:1/6 Reset Button (Clear green, top button) (NOTE: Press and release to stop processor.)

OutputsO:2/0 Heater and pump 2 (Heater is attached to pump 1. Pump 2 for small tank.)O:2/1 Valve 1 (For circulating small tank)

O:2/2 Valve 2 (For pumping contents of small tank into large tank)O:2/3 Valve 3 (For circulating large tank)O:2/4 Valve 4 (For final draining of biodiesel into dry wash towers)O:2/5 Valve 5 (For circulating large tank)O:2/6 Valve 6 (For glycerin draining)O:2/7 Pump 1 (On large tank)

Fig. 4 – The input/output for the AB 503 PLC


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The process happens in three phases. To start, the operator will add the desired amount ofWVO oil into the larger 60-gallon tank. For the reactants, the operator will measure out avolume of 25% methanol for the amount of oil and 6.25 grams of lye for every liter of oil used.During the first phase, the operator will add 75% of the measured reactants (the remaining 25%of lye should be kept in an airtight container until it is needed). The methanol and lye will be

added to the smaller 20-gallon tank.

Then the operator will press the ―Start‖ button on the PLC panel. This will open valve #1 onthe small 20-gallon tank, valve #3 and #5 on the large tank, and turn on both pumps and theheater. Once the oil in the 60 gallon reacts at 120° F (~49° C) (via a thermometer attached to thetank) a 15 minute timer will begin counting. This is to ensure that all of the oil is thoroughlyheated. Once the 15 minutes are up, valve #2 on the small tank will open and begin pumping thesodium methoxide from the small tank into the 60 gallons reactor. Valve #1 will close 5 secondslater; the large tank will continue to circulate to stir the mixture. Once Fluid Level Sensor #1(located in the bottom of the sodium methoxide small tank) reads empty, a 5 second timer will begin counting to make sure the tank is empty before turning off pump #2. The large tank will

continue to circulate for 1 hour after Fluid Sensor reads empty.

After one hour, both valves and pump 1 will shut off. A 6-hour timer will then start. This 6-hour timer goes to a counter, and must reach 6 hours twice (be done because the individual timercan only reach 9 hours and the process needs a 12 hour settling period). After 12 hours passes,valve #6 will automatically opens to drain glycerin from the 60 gallon reactor. It will close whenthe fluid level sensor #2 goes false (Sensor #2 is on the top of the large 60-gallon reactor). The program will now wait for the operator to add in the remaining 25% of the reactants and pressthe start button. Once the start button is pressed, the processor will carry out the same steps as in phase one.

4- Heating Elements

The application of heat is required to speed up the chemical reaction and reducing the oil

viscosity as well as remove the remaining water content from the oil. For this system, a

submerged heating element was used to supply the required heat. The chosen heating element is

standard submersible water heating element with 1000 Watts of power and an AC voltage

requirement of 120 Volts. This will fit perfectly with the designed power scheme.

Conclusions

The result of the first phase of the senior project work is an automated processor that iscapable of producing biodiesel with very limited operator interaction. For the system operators,a set of complete work instructions have been written to go along with the processor. The produced biodiesel was analyzed by the chemistry department and we believe it does meet theASTM standards. It was used successfully in running an AMICO diesel engine AD 186FE.

Acknowledgements

This project’s advisors would like to acknowledge the efforts of our former student DrewVandegriff for working on the proof of concept for this project. We would like also thank Jason


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Queen, Brian Reed, Allison Springer, Justin Stephens and Matthew Parrott for designing andmanufacturing of the filtration system. Furthermore, would like to acknowledge the efforts ofBrent Moore, for working long hours on this project and leading the efforts of his groupcomposed of Will Enicks, Kris Leeper, and Stephen Tischart. Moreover, we would like to thankVan Eric Short of the ECE Department for his help in programming the PLC. Finally, we would

like also to thank Mr. Barry Allison and Mrs. Pauline Reyna for proof reading this manuscript.

Bibliography

1) http://www.eia.doe.gov/oiaf/analysispaper/biodiesel/index.html 2) Y. Zhang, M.A. Dube, D.D. McLean, M. Kates, ―Biodiesel production from waste

cooking oil: 1. Process design and technological assessment, ―Elsevier , Bioresource

Technology 89 (2003) 1 – 16.3) Purolite is a registered trademark of The Purolite Company, 2010. For more information see

http://purolite.com/RelId/33637/ISvars/default/Home.htm.4) http://journeytoforever.org/biodiesel_aleks.html5) http://purolite.com/customized/uploads/pdfs/FAQ_PD206_Jan_25_07.pdf6) http://en.wikipedia.org/wiki/Biodiesel_production

7)

http://turnerbiodiesel.com/yahoo_site_admin/assets/docs/Methanol_washing_of_PD_2065345643.319101037.pdf
http://www.eia.doe.gov/oiaf/analysispaper/biodiesel/index.htmlhttp://www.eia.doe.gov/oiaf/analysispaper/biodiesel/index.htmlhttp://www.eia.doe.gov/oiaf/analysispaper/biodiesel/index.html

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