Prof.Dr. Mohamed M. El-Kassaby BIODIESEL FUEL Prepared by Professor Dr/ Mohamed M. El-Kassaby Biodiesel Fuel – Prof. Mohamed El-Kassaby

Prof.Dr. Mohamed M. El-Kassaby

BIODIESEL FUEL

Prepared by

Professor Dr/ Mohamed M. El-Kassaby

Biodiesel Fuel – Prof. Mohamed El-Kassaby


What is it? Biodiesel is a liquid fuel that can replace regular

diesel fuel. It’s made from vegetable oil. Biodiesel is produced from any fat or oil such

as soybean oil. The production processes for biodiesel are well known.

Biodiesel can run diesel engines that are commonly found in big vehicles such as trucks,

buses, or boats.

On the island of Maui, Biodiesel fuel is already available to county and private fleets.


• Biodiesel fuels begin to spread out in a large scale in many countries such as USA, Italy, Germany and Denmark.

• The National Biodiesel Board has released the following sales volume estimates for the US:

• 2006 -- 250 million gallons2005 -- 75 million gallons2004 -- 25 million gallons2003 -- 20 million gallons2002 -- 15 million gallons2001 -- 5 million gallons2000 -- 2 million gallons1999 -- 500,000 gallons


Why Biodiesel? Regular diesel fuel particulates are

carcinogenic (can cause cancer).

Using biodiesel fuel, or blending it with regular diesel fuel, can reduce the production

of these cancer-causing emissions. In other words, it’s healthier!


Biodiesel can be made from waste vegetable oil (such as used oil from deep fryers at

restaurants).

This waste oil can be difficult to dispose of. Making fuel out of it can put it to a good use,

and at the same time, reduce disposal problems.


Biodiesel is a renewable fuel.

Biodiesel can help create new jobs; also, keeping our air clean helps everybody enjoy

life more.

Biodiesel may be used in existing diesel engines without necessitating engine

modifications, and its use does not result in a shortening of engine life or the need for more

frequent servicing.


• What are the benefits of Biodiesel?

• Biodiesel has many environmentally beneficial properties. The main benefit of biodiesel is that it can be described as ‘carbon neutral’. This means that the fuel produces no net output of carbon in the form of carbon dioxide (CO2). This effect occurs because when the oil crop grows it absorbs the same amount of CO2 as is released when the fuel is combusted. In fact this is not completely accurate as CO2 is released during the production of the fertilizer required to fertilize the fields in which the oil crops are grown.


• Biodiesel is rapidly biodegradable and completely non-toxic, meaning spillages represent far less of a risk than fossil diesel spillages.

• Biodiesel has a higher flash point than fossil diesel and so is safer in the event of a crash.



• What are the main issues when switching from conventional diesel to biodiesel?

• The main operating issues are cold weather operability, engine and fuel system compatibility, and the solvency properties of biodiesel. B100 does not flow as well as petroleum diesel in cold temperatures, and requires special additives or fuel heating systems to operate in colder climates. B100 may cause rubber seals and gaskets from engines older than 1994 to wear faster or fail. Biodiesel also acts as a solvent, which can dissolve sediments in diesel fuel tanks and clog fuel filters during an initial transition from petroleum diesel.


• Despite these issues, some fleets are successfully using B100. Berkeley, California is successfully running 100% biodiesel in 90% of their public diesel fleet vehicles including fire trucks. Using B20 minimizes or eliminates most of the concerns with B100 and is therefore more widely used.


Did you know? Biodiesel can be used in pure form or

blended with regular diesel in any proportion.

Biodiesel can even make engines smell better. An engine powered by biodiesel

actually smells like French fries!

Biodiesel fuel is a good lubricant, which helps engines to last longer.

It also has a high Cetane rating, which improves engine operation.


Adding just 20% biodiesel to regular diesel improves the diesel’s Cetane rating by 3 points, which makes it a "premium" fuel.

Biodiesel buses are in use in Europe and in the Midwestern United States.


The process Vegetable oils and animal fats are triglycerides,

containing glycerin. The biodiesel process turns the oils and fats into esters (group C=O),

separating out the glycerin. The glycerin sinks to the bottom and the biodiesel floats on top

and can be syphoned off.The process is called transesterification, which

substitutes alcohol for the glycerin in a chemical reaction, using sodium hydroxide as a catalyst.

Quantities:5 (Oil):1 (alcohol) by volume with almost twice

the weight of alcohol used from sodium hydroxide NaOH


• There are some steps to use this method in producing biodiesel fuels such as:

• Mixing of alcohol and catalyst: The catalyst is typically sodium hydroxide (caustic soda) or potassium hydroxide (potash). It is dissolved in the alcohol using a standard agitator or mixer.

• Reaction: The alcohol/catalyst mix is then charged into a closed reaction vessel and the oil or fat is added.

• The system from here on is totally closed to the atmosphere to prevent the loss of alcohol. The reaction mix is kept just above the boiling point of the alcohol (around 160 °F) to speed up the reaction and the reaction takes place. Recommended reaction time varies from 1 to 8 hours, and some systems recommend the reaction take place at room temperature. Excess alcohol is normally used to ensure total conversion of the fat or oil to its esters.


• Care must be taken to monitor the amount of water and free fatty acids in the incoming oil or fat. If the free fatty acid level or water level is too high it may cause problems with soap formation and the separation of the glycerin by-product downstream.

• Separation: Once the reaction is complete, two major products exist: glycerin and biodiesel. Each has a substantial amount of the excess methanol that was used in the reaction. The reacted mixture is sometimes neutralized at this step if needed. The glycerin phase is much more dense than biodiesel phase and the two can be gravity separated with glycerin simply drawn off the bottom of the settling vessel. In some cases, a centrifuge is used to separate the two materials faster.


• Alcohol Removal: Once the glycerin and biodiesel phases have been separated, the excess alcohol in each phase is removed with a flash evaporation process or by distillation. In others systems, the alcohol is removed and the mixture neutralized before the glycerin and esters have been separated.

• In either case, the alcohol is recovered using distillation equipment and is re-used. Care must be taken to ensure no water accumulates in the recovered alcohol stream.


• Glycerin Neutralization: The glycerin by-product contains unused catalyst and soaps that are neutralized with an acid and sent to storage as crude glycerin. In some cases the salt formed during this phase is recovered for use as fertilizer. In most cases the salt is left in the glycerin. Water and alcohol are removed to produce 80-88% pure glycerin that is ready to be sold as crude glycerin. In more sophisticated operations, the glycerin is distilled to 99% or higher purity and sold into the cosmetic and pharmaceutical markets.


• Methyl Ester Wash: Once separated from the glycerin, the biodiesel is sometimes purified by washing gently with warm water to remove residual catalyst or soaps, dried, and sent to storage. In some processes this step is unnecessary. This is normally the end of the production process resulting in a clear amber-yellow liquid with a viscosity similar to petrodiesel. In some systems the biodiesel is distilled in an additional step to remove small amounts of color bodies to produce a colorless biodiesel.



Advantages of biodiesel as diesel fuel:

• Liquid nature portability.

• Ready availability.

• Renewability.

• Higher combustion efficiency.

• Lower sulfur and aromatic content than diesel.

• Higher cetane number.

• Inherent lubricity in the neat form.

• Risk of handling, transporting & storage is less than diesel.


• High heating value, less than heating value of diesel.

• Sulfur content of petrodiesel is 20 : 50 times those of biodiesel.

• Biodegradability of biodiesel is faster 4 times than petrodiesel It’s oxygen content improves the biodegradation process , all biodiesel fuels are readily biodegradable in aquatic environment

• After 28 days all biodiesel were 77% : 89% biodegraded ,diesel only 18% biodegraded.


Disadvantages of biodiesel:

• Higher viscosity.

• Lower energy content.

• High cloud point & pour point.

• High NOx emissions.

• Lower engine speed & power.

• Injector cocking.

• High price & higher engine wear.

• Power of biodiesel is less than that of diesel by 5% at the same load.


Costs and prices: Biodiesel are using waste oil feedstock make biodiesel for 50 cents to US$1 per US gallon.

Regular diesel cost around 3 dollar per US gallon (September 2005)

(Note: Small quantities of methanol can cost the equivalent of US$8 to $10 per US gallon,

but experienced biodiesel are invariably buy it in bulk for about $2-3 per gallon.)


Yields of common crops:Crop kg oil/ha litres oil/ha lbs oil/acre US gal/acre

corn 145 172 129 18

cashew nut148 176 132 19

Oats شعير 183 217 163 23

Lupine 195ترمس 232 175 25

Cotton 273 325 244 35

Soybean 375 446 335 48

Sunflowers800 952 714 102

Jatropha 1,590 1,892 1,420 202

oil palm 5,000 5,950 4,465 635

http://en.wikipedia.org/wiki/Hectare

http://en.wikipedia.org/wiki/Hectare

http://en.wikipedia.org/wiki/Acre


• General comparison between Diesel and Biodiesel properties:

Diesel Biodiesel

• Density kgL-1 @ 15.5C 0.84 0.88

• Calorific value MJL-1 38.3 33 – 40

• Viscosity mm2s-1 @ 20C4 – 5 4 – 6

• Viscosity mm2s-1 @ 40C4 – 5 4 – 6

• Cetane number 45 45 – 65



Experimental TEST

Fuel properties Three blends of each of the biodiesel fuels

were then tested [1]. These were 5, 50 and 100 (% v/v) blends of Soya (S), Rape (R) and

Waste (W) biodiesel, (referred to as S5, S50, S100, R5, R50, R100 and W5, W50 and W100 respectively). Standard diesel fuel No 2 (ESSO

Ultra Low Sulphur Diesel ) was used for the baseline tests, and was also used to create the

biodiesel blends.


RESULTS

1- FUEL PROPERTIES






•THE END



2- ENGINE POWER


The power output of the engine will be reduced with biodiesel (biodiesel has less LHV).

W100 has the highest CN and the highest power output. This would suggest that for unblended oils CN is a better indicator of

performance than LCV.


3- SPECIFIC ENERGY CONSUMPTION


The data shows that there is little variation for 5% blends, and the 50% blends tend to show slightly higher SES than for mineral diesel.

As expected, the reduced as load is increased); and the values tend to converge to similar values near 100% load.


It is unsurprising that SEC is higher for the biodiesel fuels, given their lower LCV.

At low loads, the operating temperature is lower, which results in poor spray

characteristics as the biodiesel fuels have higher viscosity.

The net effect is that more fuel is required to produce the same power output.


4- Brake Specific NOX EMISSIONS


The difference in emissions of Bs NOx for all 5% blends compared with diesel are so small as to be negligible.

The most marked differences are observed at low loads where significant reductions in

BsNOx are observed with biodiesel. For R100 and S100, BsNOx was reduced to

approximately half of the diesel value.

BsNOx emissions were the lowest for soy biodiesel, which also has the lowest fuel borne

oxygen content (table A3).


A second reason for the lower BsNOx recorded in this study is thought to be due to the higher

viscosity of the fuels leading to poor spray characteristics that reduced combustion

efficiency and hence maximum combustion temperature [2].

It is interesting to note that Salvatore and Maddaleena [3] found that NOx in a biodiesel fuelled engine can be significantly reduced by

an EGR system that includes an oxidizing catalyst.


The convergence of BsNOx emission levels beyond 50% load is probably due to the

increased in cylinder operating temperatures that reduce the effect of the increased viscosity

of the biodiesel fuels compared with No 2 diesel.


Higher viscosity in biodiesel fuels is known to result in poorer atomization, reduced spray

penetration, decreased cone angle [4], and a greater droplet size, resulting in a lower amount of air entrainment leading to poorer combustion

efficiency and hence lowers combustion temperatures which are confirmed by the

extended ignition delays in figure 5.


SMOKE EMISSIONS At low load (up to approximately 5 kW) there is

negligible difference between the smoke emissions of any biodiesel as compared to

mineral diesel.

Beyond 25% load, the emissions of smoke are always lower than for corresponding mineral

diesel operation, except for the 5% blends where there is negligible difference, as shown

in figure 4.


As the proportion of biodiesel is increased in the blend, the emissions of visible smoke

decrease, except for the waste oil where the results from 50% blend and pure waste oil were

virtually the same. Overall, the lowest smoke emissions were always recorded with rape

blends.



IGNITION DELAY The ignition delay was calculated as the crank

angle interval between start of injection and start of combustion, (found from experimental

data).

Start of injection was defined as the crank angle where fuel line pressure first exceeded the nozzle opening pressure of 235 bar, and start of combustion was found from the heat

release rate analysis.



ConclusionA blend of 5% by volume of a biodiesel fuel in

mineral diesel does not affect any of the measured performance or emissions

characteristics.

This would imply that the addition of small quantities of biodiesel to mineral diesel is a

suitable strategy for increasing alternative fuel consumption, at least in agricultural engines.


The initial findings presented in this paper suggest that for 50:50 mixtures of biodiesel and mineral diesel, there is evidence of a two stage

ignition process, with the diesel fuel igniting first, and hence controlling the combustion pattern of biodiesel. Whether this is only a

result of blending procedure remains a subject for further research.


Ignition delay is longer with biodiesel than for mineral diesel, and shows complicated trends

where biodiesel is blended with mineral diesel. This leads to delayed combustion and lower

peak cylinder pressures than for mineral diesel, which contradicts the effects of the higher CN

of the biodiesel fuels .


• -NOx emissions were reduced at low load with negligible effect on soot; at high load soot

emissions were reduced with negligible effect on NOx. Thus the use of biodiesel fuels would

appear to present a beneficial means of manipulating the traditional NOx/smoke trade-

off. Overall, in an unmodified engine, rape derivative fuel gave the best combustion and

emissions performance.


Thank you


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Prof.Dr. Mohamed M. El-Kassaby BIODIESEL FUEL Prepared by Professor Dr/ Mohamed M. El-Kassaby Biodiesel Fuel – Prof. Mohamed El-Kassaby