Project Purpose and Objectives
The purpose of this project is to convert used cooking oil into biodiesel by way of transesterifacation with sodium methoxide in a batch reactor. The biodiesel is to be used in automobiles as a petroleum diesel substitute. The primary objective of the project is to determine an effective means to produce biodiesel, which includes a filtration process for the cooking oil before it enters the reactor and also performing different ASTM standardized tests to ensure a high purity of the biodiesel product. Using the results from the different ASTM tests, if time allows, an optimization of the biodiesel reactor should be performed to find the best conversion of reactants. The reaction will be mapped based on the viscosity and the density of the reactor contents and will correlate to the conversion of the reactants.
Another objective of the project is to complete a cost analysis on the process to check the feasibility of the reactor and, as with the previous objectives, if there is available time the process will be financially optimized.
This project offers valuable hands on experience of industrial practices when a process is created or altered. It also will provide the team with the chance to control and operate a pilot scale batch reactor and analyze the results.
Project Scope
In this project we intend to make biodiesel using recycled cooking oil and comparing it to that of biodiesel using new cooking oil. We will use a 3:1 methanol to triglyceride feed ratio with red devil lye (sodium hydroxide) as the catalyst (Vicente, 1997). We will carry this reaction out at a room temperature of approximately 25 oC. We will use ASTM standards to compare our results to. The properties we intend to measure are: free glycerin levels, density, and viscosity.
Deliverables
A project proposal oral presentation will be given on Wednesday, April 6, 2005. This will give a brief overview of our goals of the proposed project.
An oral project progress report will be given on Wednesday, May 4, 2005. This will be a brief presentation of how far we have come in accomplishing our goals for the project and what direction we will be taking in the future.
A poster presentation will be given either at the Sustainable Engineering Symposium on Tuesday, May 3, 2005, or at the Engineering Expo on Tuesday, May 17, 2005.
A final oral project presentation will be delivered during dead week of this term and a final written technical report of the project will be handed in on Friday, June 3, 2005.
A detailed economical analysis of batch biodiesel operation will be prepared. This document will cover many aspects including, but not limited to:
Minimization of waste
Optimization of oil conversion with respect to time
A projected and updated timeline for the optimization of the batch biodiesel operation along with a progress report will be available by the end of each Friday of every week up until the end of the term. These will illustrate our group’s goals and progress to accomplish the goals.
An operations manual for the batch biodiesel reactor will be created for safe and efficient operation. Our team will be running the reactor and will be looking for ways to improve the process by reading current research and by running ASTM standardized tests on each batch to check the quality of the biodiesel.
An operations manual for a specific list of ASTM standard
testing methods along with proper equipment and lab setup will be made
available for the certification of the biodiesel prepared at
Roles and Responsibilities
There are three main steps in the biodiesel production process: charging the reactor, glycerol separation and biodiesel purification. Collin will make sure that the reactor is properly charged, Tim will head up the glycerol separation and Jesse will be in charge of the biodiesel purification step. Although each team member is in charge of overseeing a certain aspect of the process, everyone will work together on all parts to better understand the entire production process. This project also includes an economic analysis and optimization which Jared will be in charge of.
The bi-weekly progress reports will be done by one of the team members for each check point. Since each team member is in charge of a different aspect of the process, each person will then be considered to be the team leader for the respective section. For example, Collin will head any work whenever a new batch is being made and Tim will then take charge once the products must be separated. Jared will be the safety coordinator, but each team member is ultimately in charge of personal protection.
Project Plan
We will be
using MS Project as a guideline to track goals and progress over the course of
the term. We will review the timeline
every week and evaluate how far we have come in accomplishing the set goals. We will use the timeline to forebode what we
anticipate we will need to do to accomplish future goals. Also, we will update the worksheet with
revisions, if needed.
Equipment
Biodiesel Process
The first step in biodiesel production is to create sodium methoxide which reacts with the cooking oil in the reactor. This process is relatively simple and only consists of a bucket and a mixer. Methanol and lye are both deposited into the bucket and mixed well to create the sodium methoxide. The sodium methoxide is then transferred to the reactor.
Before the raw cooking oil can be added to the reactor, it must be filtered to remove out impurities as small as 5 mm. A two stage filtering process will be employed. The first stage will consist of a ten inch shortening filter cone which is commonly used in restaurants to filter fryer oil so that it can be reused. Gravity will push the cooking oil through the filter where it will be deposited into a holding vessel. The oil will be pumped out of the vessel and into the next filtering stage which consists of two in-line fuel filters. These fuel filters will remove any remaining impurities. Once the oil passes through the filters, it will be pushed into the batch reactor.
The most important piece of equipment is the polyethylene batch reactor. To ensure that the reactants are well mixed, the reactor will be equipped with a pneumatic mixer and a recycle stream that is pumped from the bottom of the reactor. A pump, which heats the recycle stream, may be employed to control the temperature of the reactor; however, the current arrangement contains a simple pump without a heater. A schematic of the biodiesel process is shown in figure 1.
Figure 1.
Analytical Equipment
The viscosity and density of the reactor contents will be monitored to obtain the reaction conversion. An in-tank viscometer will possibly be employed to track the reaction conversion. This viscometer is connected to a digital monitor which displays the viscosity and time from which it was taken. The point from which the viscosity is taken should be near the middle of the reactor where the sample is well mixed. If an in-tank viscometer is not economically feasible, a capillary viscometer will be used. Samples from the reactor will be taken at specific times and analyzed to determine the viscosity using a rheometer. A hydrometer will also be used to monitor the reaction based on the density of the contents of the reactor.
Once the viscosity, time, and density are recorded for a given sample, it must be sent to a gas chromatography unit. A small amount of the liquid sample is injected with a syringe into the gas chromatography unit. The port of entry of the liquid is called the injector and is maintained at high temperatures so that the liquid vaporizes. The vaporized mixture is pushed through a tube by means of an inert carrier gas. The tube is called a chromatographic column and it is filled with particles. The column is inside of an oven which is heated. The different components of the sample migrate through the column at different rates and thus elute at different times. Once a component elutes, it is sent to a flame ionization detector. The detector heats the component with a hydrogen flame which ionizes it. The ions create a current which is proportional to the concentration of the component. The detector sends information to an integrator which creates a chromatogram which can be analyzed to determine the components and concentration of the sample. This allows the conversion of reactants to be calculated. A schematic of the gas chromatography unit is depicted below in figure 2.
Figure 2.
Once several samples are taken at various times, conversion charts of the density and viscosity will be prepared so the conversion can be tracked at all times. Note that density and viscosity are functions of time, so each conversion chart is only useful for a given temperature.
Design of Experiment
The biodiesel will be produced using a batch process using reactant quantities as mentioned in published literature. A previous experiment done by Kevin Marnell had 23 gallons of oil mixed with 4.6 gallons of methanol and 330 grams of lye. Tickell gives proportions that are similar to this past experiment, so batches will be made with reactant volumes of similar values.
The methanol and lye will be mixed in a separate container and the product, methoxide, will be combined with the oil in the reactor. This reaction will be allowed to carry out for approximately half a day. Higher purities will require longer run times. It is a possibility that a heating pump will be incorporated into the process. If this happens then run times will be shortened because higher temperatures increase the reaction rate and thus decrease the amount of time needed.
The two products of the reaction will be glycerin and biodiesel. The glycerin and biodiesel will separate out with the glycerin settling to the bottom of the reactor and then this bottom layer can then be drained out. The biodiesel must then be washed with water to remove any unreacted alcohol, catalyst and glycerin although there will be minimal amounts of each. Water is added in equal volume to the amount of glycerin removed from the system. This water-biodiesel mixture is then allowed to mix and separate out for approximately a day. The pure biodiesel product will then be drained out for testing and use.
Once the biodiesel product is obtained, different ASTM tests will then be performed to determine the purity. Tests for the viscosity, density, pH and the amount of total glycerin for the biodiesel will be performed and the results from all of the tests will collectively determine the purity of the product. An in-tank viscometer may be used to monitor the viscosity of the biodiesel in the reactor, but if it is determined that the in-tank viscometer is economically unfeasible, then a rheometer will be used to determine the viscosity. The density of the product will be found by the use of a hydrometer and results around 0.93 g/mL should be expected. The pH test will be performed using lithmus paper, making sure that the biodiesel is approximately neutral. The amount of free glycerin left in the biodiesel will be determined by gas chromatography. The GC will separate out all of the different components found in the biodiesel. Ramp rates and temperatures for the GC will follow the parameters used in ASTM test D 6584-00 and those outlined from work done by James Hyunh.
Safety and Environmental
In order to ensure a safe and environmentally sound completion of our experimental work a detailed safety plan has been developed and can be found in the appendices. This safety plan has been presented to each team member and will be followed throughout experimentation. Proper auditing will be used to ensure safe behavior.
Upon handling/disposing of materials, proper procedures will be followed, as described in the material safety data sheets.
Background
Theory
Biodiesel is an alternative to petroleum diesel fuel made
from renewable biological sources such as vegetable oils and animal fats. For this project, used vegetable oil obtained
from the Dining Services Department at
The production of biodiesel is a relatively simple process. Methodide, a product of the mixing of methanol and lye, is mixed in a batch reactor with the vegetable oil. This reaction process is called transesterification, where an oil reacts with an alcohol to form esters and glycerol. The oil and methoxide are allowed to react for approximately 10-15 hours and then left to separate. The two products of the reaction, glycerol and biodiesel will separate and the glycerol is drained off. The crude biodiesel is then rinsed with water to remove any unwanted impurities and the desired product is then collected and analyzed. The entire production process takes approximately two days, depending on the reaction temperature and purity desired. Reactions carried out at higher temperatures decrease the production time. Conversely, higher purities require more time. The reaction carried out in the reactor can be viewed below in Figure 3.
CH2-OCC-R1 R1-COO-R’ CH2-OH
Catalyst
CH-OOC-R2 + 3R’OH 
R2-COO-R’ + CH-OH
CH2-OOC-R3 R3-COO-R’ CH2-OH
Glyceride Alcohol Esters Glycerol
Figure 3.
Method of Data Analysis
Each batch of biodiesel will be analyzed by utilizing different ASTM testing methods. Tests for density, viscosity, pH and the amount of free glycerin will be used and the tests collectively will be used to determine the purity of each batch. There will not be many calculations because all of the tests will be performed on instruments that generate a recordable readout.
A hydrometer will be used to determine the density and results around 0.93 g/mL should be expected, while an in-tank viscometer may be used to monitor the viscosity of the biodiesel in the reactor. If it is determined that the in-tank viscometer is economically unfeasible, then a rheometer will be used to determine the viscosity. The pH test will be performed using lithmus paper, making sure that the biodiesel is approximately neutral. The amount of free glycerin left in the biodiesel will be determined by gas chromatography. The GC will separate out all of the different components found in the biodiesel. Ramp rates and temperatures for the GC will follow the parameters used in ASTM test D 6584-00 and those outlined from work done by James Hyunh.
Analytical Methods
The four tests for density, viscosity, pH and total glycerin were chosen because these factors seem to have the greatest influence on the fuel’s performance in an engine. The density will mainly help to determine the purity of the product. The viscosity is important because it can affect the amount of power generated by the engine. If the biodiesel it too viscous then it may clog the fuel filters and cause a loss of power. The pH of the product must be relatively neutral; between six and eight. An acidic or basic product may corrode tubes or gaskets in the engine, causing unnecessary maintenance. The amount of glycerin in the biodiesel is important for ASTM certification because the product cannot contain more than 0.2% glycerin. If the biodiesel has more that two parts per million of glycerin in the system, then the fuel will not meet the ASTM standards.