Biodiesel Report 2 Pineres-Mendoza

8/10/2019 Biodiesel Report 2 Pineres-Mendoza

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ENERGY PRACTICE REPORT

SOSE 2014Biodiesel production 2: Oil Refining

Diego Felipe Mendoza Osorio;Luis Daniel Pineres [email protected]; [email protected]


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Contents1. Introduction ............................................................................................................... 2

2. Theory and theoretical basics ................................................................................... 3

3. Rapeseed Oils Chemical and Physical properties. ................................................... 4

4. Experiment ................................................................................................................ 5

4.1. Experimental set up. ........................................................................................... 5

4.2. Reagents ............................................................................................................ 5

4.3. Process steps. .................................................................................................... 5

4.3.1 Transesterification. ....................................................................................... 5

4.3.2 Neutralization ............................................................................................... 8

4.3.3 Distillation..................................................................................................... 9

4.3.4 Separation.................................................................................................. 10

4.3.5 Density measurement ................................................................................ 11

5. Results .................................................................................................................... 12

6. Discussion ............................................................................................................... 14

7. Summary ................................................................................................................. 14

8. References .............................................................................................................. 15


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1. Introduction

Nowadays vegetable oils are used as a biomass source alternative to the normal diesel

fossil fuel. The resulting product named as Biodiesel is obtained by the transesterification

process, which involves a reaction of vegetable oils with methanol, although animaloil/fats, tallow and waste cooking oil could be used as well. Raw oil obtained directly from

the vegetables is not being produced in large scale. The main reason for this fact is that

it is too costly, that is why most of the biodiesel obtained at the present comes from the

waste vegetable oil sourced from restaurants and industrial food producers (Wha14).

The interest in biodiesel as a renewable energy resource, arise when considering its

advantages: high flash point, good lubricity, high cetane number (above 100 compared to

40 for normal diesel fuel), less pollutants emissions mainly CO2and sulfur dioxide (Bio14).

As an example in 2003 the European community decided to replace nearly 6% of the

annual consumed fossil fuels with biofuels, by the year 2010. The decision accelerated

the biodiesel production and it shows a growing trend, for instance in 2008 the annualbiodiesel production in the world was 7.75 million metric tons (Masato Kouzu, 2012).

Rapeseed oil has the greatest potential for biodiesel production; hence it will be used in

our practice. In experiment biodiesel I, the crude rapeseed oil was obtained from the seeds

by cold pressing (extrusion), in the following practice biodiesel II the transesterification

process was applied to refine the crude oil gathered previously.

Figure 1. Transesterification of triglyceride with methanol. (J.M. ENCINAR, 2010)

Transesterification consist of a reversible reaction of a triglyceride with an alcohol, theproducts formed are esters and glycerol as shown in figure 1. The glycerine molecule ofa triglyceride has three fatty acids chains attached. During esterification process, thetriglyceride reacts with alcohol, and a catalyst is used as well, usually a strong alkaline.From this reaction the products are mono-alkyl ester or biodiesel (FAME) and glycerol(Wha14).


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In the practice the alcohol used was methanol (which produces methyl esters) and thecatalyst potassium hydroxide (KOH), as products Rape Methyl Ester (from raw rapeseedoil) and glycerine were obtained. Some methanol could be added in excess to drive thereaction towards the right and ensure a complete conversion.

The experiment was executed in the laboratory N.2.36 of the Hamburg University ofApplied Sciences (HAW campus Bergedorf), which provided the equipment, chemicalsand feedstock required for transesterification. The crude oil used was obtained previouslyby the Biodiesel I experiment by cold pressing rapeseed. In this report, the procedurefollowed will be explained, the mass balances and oil conversion rate will be calculatedand compared to the values expected from similar experiments found in the literature.

2. Theory and theoretical basics

For the large scale industrial production of biodiesel, the alcohol (methanol) and the

catalyst (KOH or NaOH) are added in a stepwise manner to achieve a high yield ofbiodiesel. After that, the glycerol (glycerine) is removed at the end of each step. Most of

the manufacturing plants make use of batch reactors.

The glycerol produced after the reaction is extracted in a settling tank or using a centrifuge,

it is possible because the glycerol has a very low solubility in the esters. The dissolved

methanol is separated from the methyl esters. The unreacted excess methanol could be

then recovered and used for further transesterifications (Selahattin Umdu, 2008).

Figure 2. Rapeseed oil Transesterification flow chart. (Van Gerpen, 2005)


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The percentage of oil conversion, defined as the ratio of refined oil (FAME) to the crude

oil depends on the processing parameters, such as the molar ratio of methanol to oil, the

catalyst concentration, the time for the reaction, the type of alkaline catalyst and the

reaction temperature. Depending on the mentioned parameters, the oil conversion could

be found between the ranges of 85% to 98% (Jeong, et al., 2004). Different authors have

studied the influence of the catalyst concentration and found after transesterification, thatthe oil conversion percentage range between 90% and 98% (J.M. ENCINAR, 2010)

(Masato Kouzu, 2012).

3. Rapeseed Oils Chemical and Physical properties.

The chemical and physical properties of the rapeseed oil are majorly dependent on the

quality of the original rapeseed and the processing technology (Gis, et al., 2011). For this

experiment, the Rapeseed oil used was obtained from rapeseed with a 5% of moisture

content. The technology used was a Screw extruder P500R from Anton Fries Corporation

getting from the feedstock around 30% of oil. Literature values for the rapeseed oilproperties are shown in the table 1.

Table 1. Properties of rapeseed oil and sub products.

Density [g/l]@20C

Viscosity[mm/s]@ 20C

Higher HeatingValue [J/g]

Lower HeatingValue [J/g]

RME 886,00-900,001 6,00-9,002 40370,003 37458,004Rapeseed

oil 914,505 74,196 40200,007 37620,008

Methanol 794,009 0,73710 22900,0011 20100,0012

Glycerin 1260,0013 741,0014 19000,0015 16000,0016

1(Gis, et al., 2011)2(Gis, et al., 2011)3(Delucchi, et al., 2003)4(Delucchi, et al., 2003)5(Temperature dependence of density and viscosity of vegetable oils., 2012)6

(Temperature dependence of density and viscosity of vegetable oils., 2012)7(Parrilla, et al.)8(Parrilla, et al.)9(Olah, 2011)10(Viscosities of vegetable oils and fatty acids., 1992)11(Olah, 2011)12(Olah, 2011)13(Emissions and Temperature Measurements in Glycerol Flames, April 2224, 2012 )14(Emissions and Temperature Measurements in Glycerol Flames, April 2224, 2012 )15(Yaar, 2012)16(Emissions and Temperature Measurements in Glycerol Flames, April 2224, 2012 )


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4. Experiment

4.1. Experimental set up.

The following instruments and tools were used for the practice:

- Rotary evaporator Heidolph Laborota 4003.

- Centrifuge Hettlich Universal 30 F

- Density meter Heraeus

- Digital weighing scales.

- Vessels

- Magnetic stirrer.

4.2. Reagents

In order to achieve the processes of the experiment, the next reagents were used and

provided by the HAW laboratory staff.

- Methanol.

- Potassium Hydroxide (KOH) pellets.- Hydrochloric acid (HCL).

4.3. Process steps.

For the process of obtaining refined rapeseed oil RME (Rapeseed Methyl Esther) several

chemical separation steps are defined.

4.3.1 Transesterification.

For this step, the water bed of the rotary evaporator was preheated to 60 C. A fixed

feedstock weight (Rapeseed oil) of 120g was prepared into the flask, as shown in figure

3 and figure 4.


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Figure 5. Weighting the HCL needed

A similar procedure is used to calculate the catalyst (KOH) weight, based in literature

values (Kaltschmitt, et al., 2009)

=

Where = 880

; = 56

; = 1/12(Kaltschmitt, et al., 2009).

The rapeseed oil weight was stablished from the beginning of the experiment as 120g.

= 0.63

The catalyst and the methanol are mixed in the little flask shown in figure 5, and after 10

minutes the mixture was introduced in the rapeseed oil flask. This process was pictured

in the figure 6.


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Figure 6. Mixing the reagents with the crude rapeseed oil.

After the reagents where mixed, the flask was installed in the rotary evaporator and the

machine was set at 100 rpm during 60 min.

4.3.2 Neutralization

After the transesterification process, a neutralization process took place in the experiment.

The reagent used to neutralize the catalyst in order to reduce the amount of soapproduced in the separation process. The mass of the neutralizer (Hydrochloric acid) was

calculated with the next equation (Kaltschmitt, et al., 2009), and the value was weighted

and registered in figure 5.

=

Where

= 0.63;

= 84 %;

= 1;

= 56

;

= 36.4

;

=

10 %; = 1; (Kaltschmitt, et al., 2009).

= 3.87

The neutralizer was added to the transesterified oil and the mixture was stirred to ensure

the mixing. The pH of the mixture was measured and as an additional measurement, the


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Figure 10. Settings in the centrifuge machine.

During this process, water and methanol where separated from the mixture by evaporation

and pumping.

4.3.4 Separation

After the distillation, the oil need to be separated from the remaining glycerin content. To

achieve this, the whole mixture was introduced in centrifuge tubes and processed in the

centrifuge machine as shown in figure 9. This device (Hettich Universal 30F) was set up

to 11000 RPM for 15 min (figure 10).

Figure 9. Transesterified oil neutralized.


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After the separation process, the glycerine was separated from the oil as shown in the

figure 11.

Figure 11. RME and glycerin separated.

4.3.5 Density measurement

As parameters to check the process, the densities of the different sub-products from the

original rapeseed oil were measured. This step is performed with the Density meterHeraeus. Due to the fact that this device receive substance flow as an input, acetone was

used to clean the conducts and to achieve more accurate results. The density of Methanol,

Rapeseed oil, Rapeseed methyl ester (RME) oil and water was expected to be measured.


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Table 2. Measured density values.

5. Results

- Densities: As a result of the process, the measured densities of the sub-

products (methanol, rapeseed oil, transesterification distillates and Rapeseed

methyl ester oil) are shown in the table 2. From the chemical reactions areexpected the two distillates in the transesterification process to be water and

methanol.

Density @ 21.07 C [g/l]

Value 1 Value 2 Value 3 Mean Value

RME 904,7 903 900,7 902,80RapeseedOil 907,3 905,9 909,8 907,67

Methanol 769 773,9 790,1 777,67

Distillate 1 857,7 854,6 857 856,43

Distillate 2 815,5 816,5 816,2 816,07

- Acidity: The pH registered for the rapeseed oil was between 4 and 5, and it is

clearly observed that the oil after neutralization had a higher acidity (pH 6) as

can be seen in the figure 7.

- Mass balance: A balance of mass for the process can be computed according

to the next formula:

+ + + = + +

Where is the mass loss in the process (RME stuck to the flasks, etc.) and the distillates.

From this balance, the items of right side of the equation were weighted (figure 12).


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6. Discussion

As it could be seen from the section 5, the oil percentage conversion of crude rapeseed

oil to RME was about 92.63%. This yield is consistent to the conversion range of 85% to

98% found in the literature (Jeong, et al., 2004) (J.M. ENCINAR, 2010). Although a higher

percentage of oil conversion could be expected, this value is dependent on the processing

parameters. For instance increasing the catalyst concentration (KOH) or the molar ratio

of methanol to oil up to a given value, could give a better oil percentage conversion. It is

necessary to consider some losses of oil remaining in the flasks, centrifuge containers

and pipets used for carrying out the practice.

Regarding the densities of the feedstock and products, it could be deduced from table 2

that the product RME had a lower density (902.80 g/l) than the rapeseed crude oil (907.67g/l) as it is expected after a transesterification. The methanols density before the

experiment (777.67 g/l) was nearly the literature value of 794 g/l. There are some

inconsistencies with the densities values for distillates 1 and 2. These educts are expected

to be water and methanol according to the practice guide (Kaltschmitt, et al., 2009). The

density values were 856,43 g/l and 816,07 g/l, neither of them matched with the literature

values for water and methanol density at the given temperature. It seems that the

distillates are not pure substances, but a mixture. Therefore a more detailed analysis

about the distillates is required.

7. Summary

Fatty acids Methyl ester oil is becoming extensively applied for industrial and transport

applications. It is an important additive for biodiesel (7% in content), hence a refining

process by means of transesterification is required for lowering its kinematic viscosity. The

scope of the practice was to compare the literature values for density and refined oil yield

with the experimental results. The experiment was successfully performed, the amount of

refined oil obtained matched the theoretical expected values (around 93%). From the

practice and theory it could be expected that the oil conversion percentage depends on

the balance of the reagents and educts as well as the catalyst concentration.


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8. ReferencesBiodiesel. [Online] Cyberlipid.[Cited: April 09, 2014.] http://www.cyberlipid.org/glycer/biodiesel.htm.

Delucchi, Mark A. and Lipman, Timothy . 2003.ENERGY USE AND EMISSIONS FROM THE LIFECYCLE OF

DIESEL-LIKE FUELS DERIVED FROM BIOMASS. Berkeley : Institute of Transportation Studies, 2003.

Emissions and Temperature Measurements in Glycerol Flames. Jiang, Lulin, Taylor, Robert and Agrawal ,Ajay. April 2224, 2012 .Tuscaloosa : Central States Section of the Combustion Institute , April 2224,

2012 . Spring Technical Meeting.

Gis, Wojciech, Zoltowski, Andrzej and Bochenska, Anna. 2011.PROPERTIES OF THE RAPESEED OIL

METHYL ESTERS AND COMPARING THEM WITH THE DIESEL OIL PROPERTIES. 2011. p. 3.

J.M. ENCINAR, J.F. GONZLEZ,A. PARDAL,G. MARTNEZ. 2010.Transesterification of Rapeseed Oil with

Methanol in the Presence of Various Co-Solvers. Third International Symposium on Energy from Biomass

and Waste, Venice Italy. 2010.

Jeong, G. T., et al. 2004.Production of Biodiesel Fuel by Transesterification of Rapeseed oil.Applied

Biochemistry and Biotechnology. Humana Press Inc., 2004, Vols. 113-116.

Kaltschmitt, Martin, Hartmann, Hans and Hofbauer, Hermann. 2009.Energie aus Biomasse.

Grundlagen, Techniken und Verfahren. s.l. : Springer, 2009.

Masato Kouzu, Jyu-suke Hidaka. 2012.Transesterification of vegetable oil into biodiesel catalyzed by

CaO: A review. Fuel:The Science and Technology of Fuel and Energy . 2012, Vol. 93, 1-12.

Olah, George Andrew. 2011.Methanol economy. Aarhus : Danish Methanol Association, 2011.

Parrilla, J. and Corts, C.Modelling of droplet burning for rapeseed oil as liquid fuel. Zaragoza : University

of Zaragoza.

Selahattin Umdu, Emin. 2008.Methyl Ester Production From Vegetable Oils On Heterogeneous Basic

Catalysts. Izmir : Graduate School of Engineering and Sciences of Izmir Institute of Technology, 2008.

Temperature dependence of density and viscosity of vegetable oils. Esteban, Bernat, et al. 2012.2012,

Biomass and Bioenergy, pp. 164-171.

Van Gerpen, J. 2005.Biodiesel Processing and Production. Fuel Processing Technology. 2005, Vol. 86,

1097-1107.

Viscosities of vegetable oils and fatty acids. Noureddini, Hossein, Teoh, B. and Clements, Davis. 1992.

s.l. : University of Nebraska-Lincoln, 1992, Papers in biomedical, pp. 1189-1191.

What is Biodiesel? [Online] [Cited: April 09, 2014.] http://www.esru.strath.ac.uk/EandE/Web_sites/02-03/biofuels/what_biodiesel.htm.

Yaar, Demirel. 2012.Energy and Energy Types. Energy, Production, Conversion, Storage, Conservation,

and Coupling. s.l. : Springer, 2012, p. 39.

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