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Transcript of Final Project
PRODUCTION OF ETHYL ALCOHOL FROM MOLASSES USING ASPEN PLUS
A project report submitted in partial fulfillment for the award of degree of
BACHELOR OF TECHNOLOGY
IN
CHEMICAL ENGINEERING
SUBMITTED BY
T.P.RL.SINDHURI K.SURESH KUMAR
B.JOGENDRA KUMAR R.S.RAVI KISHORE
Under the Esteemed guidance of
Dr.ADITYA MUKHARJEE, PhD
PROFESSOR
Department of Chemical Engineering
Gayatri Vidya Parishad College of Engineering
(Affiliated to Jawaharlal Nehru Technological University, Kakinada, A.P.)
Madhurawada, Visakhapatnam – 530048
2007-2011
GAYATRI VIDYA PARISHAD COLLEGE OF ENGINEERING
DEPARTMENT OF CHEMICAL ENGINEERING
CERTIFICATE
This is to certify that the project work titled “PRODUCTION OF ETHYL ALCOHOL FROM
MOLASSES USING ASPEN PLUS” During the academic year (2010-2011) under the guidance of
Dr.ADITYA MUKHARJEE,PhD, professor is submitted in partial fulfillment for the award of
degree of Bachelor of Technology in Chemical Engineering.
Dr.ADITYA MUKHARJEE, PhD, Dr.B.Srinivas, M.Tech, PhD,
Professor, Head of the Department,
ACKNOWLEDGEMENT
It is our privilege to express our gratitude to our project guide Dr.Aditya Mukharjee, Professor, Department of Chemical Engineering, G.V.P. College of Engineering for his incessant co-operation and suggestions towards the completion of the technical report.
Heartfelt thanks to Prof. B.Srinivas, HOD and support provided by the all the faculty members of the department is greatly acknowledged.
T.P.R.L.Sindhuri
K.Suresh Kumar
Jogendra Behara
R.S.Ravi Kishore
INDEX
1. INTRODUCTION
2. DESCRIPTION
(I)BLOCK DIAGRAM
(II)RAW MATERIALS
(III)REACTION INVOLVED
(IV)PROCESS
(V)MATERIAL BALANCE
3. SIMULATION
(I)DESIGN
(II) ASSUMPTIONS
(III) DATA SUPPLIED
(IV) RESULTS
1. CONCLUSION
ABSTRACT
This project mainly deals with the production of “Ethyl alcohol” from
molasses using ASPEN Plus software where the entire process can be
simulated just by using it. Our aim is to produce 10tonne of ethanol/day
which is of 95% concentrated and this would help to know the conditions
that has to be applied practically and various conditions under which the
productivity could be increased and also to find many ways for troubleshoot
of many practical problems and how to decrease the adverse affects that are
encountered during the production process as ethanol is parental compound
for many processes. With actual operating conditions and reliable
thermodynamic data we could simulate actual plant behavior. Ethyl Alcohol
from molasses is the most familiar process industrially as it is very
economical because the raw materials used for this process are by-products
of sugar manufacturing process; hence they are cheaper and could be
handled easily. Moreover when compared to the other processes of ethanol
production like from starch etc., needs the raw materials to be pre-treated
like hydrolyzed to fermentable sugars by the action of malts and molds
before the process starts. But here, sugar can be directly converted into
ethanol. This project mainly with deals how to make this process more
effective and the results show the nearer values to the practical values that
are to be adopted in the plant.
INTRODUCTION
Ethanol or ethyl alcohol, CH3CH2OH, has been described as one of the
most exotic synthetic oxygen-containing organic chemicals because of its
unique combination of properties as a solvent, a germicide, a beverage, an
antifreeze, a fuel, a depressant, and especially because of its versatility as a
chemical intermediate for other organic chemicals. Ethanol is one of the
most important renewable fuels contributing to the reduction of negative
environmental impacts generated by the worldwide utilization of fossil
Fuels. However, the production of ethanol is a complicated process. The
transformation of such biological resources as energy-rich crops (like sugar
cane or corn) or lignocellulosic biomass requires the conditioning or
pretreatment of the feed stocks for fermenting organisms to convert them
into ethanol. Then, aqueous solutions of ethanol should be concentrated for
obtaining hydrous ethanol. This product has to be dehydrated in order to be
utilized as an oxygenate for gasoline, the trade form in which ethanol is
mostly employed in the transportation sector. The complexity of this process
partly explains why fuel ethanol has not played a leading role in comparison
to cheaper oil derived fuels. There are various processes in which ethanol
could be produced. But the major process in which it is produced
industrially is using molasses. This process is more economical when
compared to all other process as here ethanol is produced from the by-
product of sugar industry. Ethanol is made from a variety of agricultural
products such as grain, molasses, fruit, whey and sulfite waste liquor.
Generally, most of the agricultural products mentioned above command
higher prices as foods, and others, e.g., potatoes, are uneconomical because
of their low ethanol yield have generated renewed interest in ethanol
fermentation, but its use still depends on the availability and cost of the
carbohydrate relative to the availability and cost of ethylene. Sugar and grain
prices, like oil prices, have risen dramatically since 1973. According to the
results that are obtained from the world’s utilization of ethanol records,
maximum ethanol used will be from molasses.
RAW MATERIAL(1 TON) ETHANOL YIELD(LITERS)
MOLASSES
SUGAR CANE
FRESH CASSAVA
SORGHUM
COCONUT JUICE
260
70
180
70
83
PHYSICAL PROPERTIES OF ETHANOL:
Ethanol is a volatile, colorless liquid that has a slight odor. It burns with a
smokeless blue flame that is not always visible in normal light. The
physical properties of ethanol stem primarily from the presence of
its hydroxyl group and the shortness of its carbon chain. Ethanol’s
hydroxyl group is able to participate in hydrogen bonding, rendering it
more viscous and less volatile than less polar organic compounds of
similar molecular weight. Ethanol is a versatile solvent, miscible with
water and with many organic solvents, including acetic acid,
acetone, benzene, carbontetrachloride, chloroform, diethyl ether, ethylene
glycol, glycerol, nitromethane, pyridine, and toluene. It is also miscible
with light aliphatic hydrocarbons, such as pentane and hexane, and with
aliphatic chlorides such as trichloroethane and tetrachloroethylene.
Ethanol’s miscibility with water contrasts with that of longer-chain
alcohols (five or more carbon atoms), whose water miscibility decreases
sharply as the number of carbons increases. The miscibility of ethanol
with alkanes is limited to alkanes up to undecane, mixtures
with dodecane and higher alkanes show a miscibility gap below a certain
temperature (about 13 °C for dodecane). The miscibility gap tends to get
wider with higher alkanes and the temperature for complete miscibility
increases. Ethanol-water mixtures have less volume than the sum of their
individual components at the given fractions. Mixing equal volumes of
ethanol and water results in only 1.92 volumes of mixture. Mixing
ethanol and water is exothermic. At 298 K, up to 777 J/mol are set free
Mixtures of ethanol and water form an azeotrope at about 89 mole-%
ethanol and 11 mole-% water or a mixture of about 96 volume percent
ethanol and 4% water at normal pressure and T = 351 K. This azeotropic
composition is strongly temperature and pressure-dependent and vanishes
at temperatures below 303 K.
The graph shows the heat of mixing of mixture of ethanol and water. And
the graph which is drawn below gives the equilibrium curve of the
mixture of ethanol and water (including azeotrope).
FERMENTATION:
DEFINITION: In general there are 2 definitions for fermentation
(a) The anaerobic conversion of sugar to carbon dioxide and alcohol by yeast.
(b) Any of a group of chemical reactions induced by living or nonliving
ferments that split complex organic compounds into relatively simple
substances. Fermentation in food processing typically is the conversion
of carbohydrates to alcohols and carbon dioxide or organic acids
using yeasts, bacteria, or a combination thereof, under anaerobic conditions.
A more restricted definition of fermentation is the chemical conversion
of sugars into ethanol. The science of fermentation is known as zymurgy.
Fermentation usually implies that the action of microorganisms is desirable,
and the process is used to produce alcoholic beverages such as wine, beer,
and cider. Fermentation is also employed in the leavening of bread, and for
preservation techniques to create lactic acid in sour foods such
sauerkraut, dry sausages,kimchi and yogurt, or vinegar (acetic acid) for use
in pickling foods. Fermentation processes from any material that contains
sugar can derive ethanol. The many and varied raw materials used in the
manufacture of ethanol via fermentation are conveniently classified under
three types of agricultural raw materials: sugar, starches, and cellulose
materials. Sugars (from sugar cane, sugar beets, molasses, and fruits) can be
converted to ethanol directly. Starches (from grains, potatoes, root crops)
must first be hydrolyzed to fermentable sugars by the action of enzymes
from malt or molds. Cellulose from wood, agricultural residues, waste
sulfite liquor from pulp and paper mills) must likewise be converted to
sugars, generally by the action of mineral acids. Once simple sugars are
formed, enzymes from yeast can readily ferment them to ethanol.
USES OF ETHANOL:
Ethanol is the parent compound for many products that we use daily. Some
of its uses are as follows.
AS A FUEL:
The largest single use of ethanol is as a motor fuel and fuel additive.
Brazil has the largest national fuel ethanol industry. Gasoline sold in Brazil
contains at least 25% anhydrous ethanol. Hydrous ethanol (about 95%
ethanol and 5% water) can be used as fuel in more than 90% of new cars
sold in the country. Brazilian ethanol is produced from sugar cane and noted
for high carbon sequestration. The U.S. uses Gasohol (max 10% ethanol)
and E85 (85% ethanol) ethanol/gasoline mixture. Ethanol may also be
utilized as a rocket fuel, and is currently in light weight rocket-powered
racing aircraft.
ALCOHOLIC BEVERAGES:
Ethanol is the principal psychoactive constituent in alcoholic beverages,
with depressant effects on the central nervous system. It has a complex mode
of action and affects multiple systems in the brain, the most notable one
being its agonistic action on the GABA receptors. Similar psycho actives
include those that also interact with GABA receptors, such as gamma-
hydroxybutyric acid (GHB). Ethanol is metabolized by the body as an
energy-providing nutrient, as it metabolizes into acetyl CoA, an intermediate
common with glucose and fatty acid metabolism that can be used for energy
in the citric acid cycle or for biosynthesis. Alcoholic beverages vary
considerably in ethanol content and in foodstuffs they are produced from.
Most alcoholic beverages can be broadly classified as fermented beverages,
beverages made by the action of yeast on sugary foodstuffs, or distilled
beverages, beverages whose preparation involves concentrating the ethanol
in fermented beverages by distillation. The ethanol content of a beverage is
usually measured in terms of the volume fraction of ethanol in the beverage,
expressed either as a percentage or in alcoholic proof units.
FEED STOCK:
Ethanol is an important industrial ingredient and has widespread use as a
base chemical for other organic compounds. These include ethyl halides,
ethyl esters, diethyl ether, acetic acid, ethyl amines, and to a lesser
extent butadiene.
ANTISEPTIC:
Ethanol is used in medical wipes and in most common antibacterial hand
sanitizer gels at a concentration of about 62% v/v as an antiseptic. Ethanol
kills organisms by denaturing their proteins and dissolving their lipids and is
effective against most bacteria and fungi, and many viruses, but is
ineffective against bacterial spores.
TREATMENT FOR POISONING BY OTHER ALCOHOLS:
Ethanol is sometimes used to treat poisoning by other, more toxic alcohols,
in particular methanol and ethylene glycol. Ethanol competes with other
alcohols for the alcohol dehydrogenase enzyme, lessening metabolism into
toxic aldehyde and carboxylic acid derivatives, and reducing one of the more
serious toxic effects of the glycols, their tendency to crystallize in
the kidneys.
SOLVENT:
Ethanol is miscible with water and is a good general purpose solvent. It is
found in paints, tinctures, markers, and personal care products such as
perfumes and deodorants. It may also be used as a solvent in cooking, such
as in vodka sauce.
DESCRIPTION:
1. BLOCK DIAGRAM:
2. RAW MATERIALS:
MOLASSES: The most widely used sugar for ethanol fermentation is
blackstrap molasses which contains about 35 – 40 wt% sucrose, 15 – 20 wt
% invert sugars such as glucose and fructose, and 28 – 35 wt% of non-sugar
solids. Blackstrap (syrup) is collected as a by-product of cane sugar
manufacture. The molasses is diluted to a mash containing ca 10 –20 wt%
sugar. After the pH of the mash is adjusted to about 4 – 5 with mineral acid,
it is inoculated with the yeast, and the fermentation is carried out non-
aseptically at 20 – 32°C for about 1 – 3days. The fermented beer, which
typically contains ca 6 – 11 wt% ethanol, is then set to the product recovery
in purification section of the plant.
YEAST: The organisms of primary interest to industrial operations in
fermentation of ethanol include Saccharomyces cerevisiae, S. uvarum,
Schizosaccharomyces pombe, and Kluyueromyces sp. Yeast, under anaerobic
conditions, metabolize glucose to ethanol primarily by way of the Embden-
Meyerhof pathway. The overall net reaction involves the production of 2
moles each of ethanol, but the yield attained in practical fermentations
however does not usually exceed 90 – 95% of theorectical. This is partly due
to the requirement for some nutrient to be utilized in the synthesis of new
biomass and other cell maintenance related reactions. A small concentration
of oxygen must be provided to the fermenting yeast as it is a necessary
component in the biosynthesis of polyunsaturated fats and lipids. Typical
amounts of O2 maintained in the broth are 0.05 – 0.10 mm Hg oxygen
tension. The relative requirements for nutrients not utilized in ethanol
synthesis are in proportion to the major components of the yeast cell. These
include carbon oxygen, nitrogen and hydrogen. To leaser extent quantities of
phosphorus, sulfur, potassium, and magnesium must also be provided for the
synthesis of minor components. Minerals (i.e. Mn, Co, Cu, Zn) and organic
factors (amino acids, nucleic acids, and vitamins) are required in trace
amounts. Yeast are highly susceptible to ethanol inhibition. Concentration of
1-2% (w/v) is sufficient to retard microbial growth and at 10% (w/v)
alcohol, the growth rate of the organism is nearly halted. To be specific yeast
is a eukaryotic micro-organism. Not all yeasts are suitable for brewing.
WHY YEAST?
According to P.Gunasegaram (1999), the yeast Saccharomyces
cerevisiae and facultative bacterium Zymomonas mobilis are better
candidates for industrial alcohol production. Z. mobilis possesses advantages
over S. cerevisiae with respect to ethanol productivity and tolerance. But the
bottlenecks in Z. mobilis are:
i) its inability to convert complex carbohydrate polymers like
cellulose, hemicellulose, and starch to ethanol,
ii) its resulting in byproducts such as sorbitol, acetoin, glycerol
and acetic acid,
iii) Formation of extracellular levan polymer.
As reported in batch fermentation, sugar concentrations as high as 223
g/l could be fermented to 105 g/L ethanol in 70 hours. The percentage
theoretical yield was 92%. Whereas in a continuous fermentation using
mixed cultures of Z. mobilis and S. cerevisiae, production of 54.3 g/L of
ethanol was observed within 3 days. A high ethanol productivity of 70.7
g/L/hr was obtained with a final ethanol concentration of 49.5 g/L and yield
of 0.5 g/g. this amount to 98% of the theoretical yield and 99% substrate
conversion.
WATER:
Molasses when introduced into the fermenter is first diluted because
molasses is basically a thick syrup which cannot be fermented easily as
choking of materials takes place and this thick liquid may stick to the walls
of the reactor and disturbs the entire section. To avoid this molasses is first
diluted hence water also takes a part among raw materials.
REACTION INVOLVED:
The main reaction involved in this process is molasses containing 20-25% of
glucose will be decomposing into ethanol molecules and carbon dioxide
molecules. This process takes place in the fermentation cell where yeast
being the catalyst.
C6H12O6 ----yeast------> 2 C2H5OH + 2 CO2
Thus from the above reaction we can deduce that 1 molecule of glucose
decomposes into 2 molecules of ethanol and 2 molecules of carbon dioxide
in the presence of yeast. A small amount of oxygen also supplied for the
yeast to get multiplied inside the reactor.
PROCESS:
As it was already mentioned that molasses is the by-product of sugar
industry, molasses is first diluted with water. For the sugar content of nearly
20-25% (w), 75-80%(w) is added and will be sent into fermenter and allow
them to react or ferment for 1-3days. In the fermenter, the formation of ethyl
alcohol takes place. In brewing, alcoholic fermentation is the conversion of
sugar into carbon dioxide gas (CO2) and ethyl alcohol. This process is
carried out by yeast cells using a range of enzymes. This is in fact a complex
series of conversions that brings about the conversion of sugar to CO2 and
alcohol. To be specific yeast is a eukaryotic micro-organism. Not all yeasts
are suitable for brewing. In brewing we use the sugar fungi form of yeast.
These yeast cells gain energy from the conversion of the sugar into carbon
dioxide and alcohol. The carbon dioxide by-product bubbles through the
liquid and dissipates into the air. In confined spaces the carbon dioxide
dissolves in the liquid making it fizzy. The pressure build up can be quite
immense. Certainly enough to cause the explosion of a sealed glass bottle.
The other by-product alcohol, remains in the liquid which is great for us but
not for the yeast, as the yeast dies when the alcohol exceeds its tolerance
level. Wine yeast is more tolerant at a range of 10-15%. Specially cultured
strains of yeast with the correct environment can withstand alcohol levels up
to 21% alcohol. Then the beer stream which consists of alcohol (10-15%)
and water mixture and CO2 will be separated into two different streams
where CO2 will be sent into the beer column where the CO2 stream will be
separated by varying temperature or pressure conditions. In general pressure
would be increased to separate the gas stream because if temperature is
increased, the quality of alcohol is affected. Much of the CO2 that is
generated during the fermentation process can be captured and converted
into marketable products, such as dry ice, liquid CO2 for soft drinks, fire-
fighting foams, filtration products and various industrial uses. After
separating CO2, the ethanol-water mixture will be sent into distillation
column and the ethanol will separated and collected at the top and water at
the top. In practice, maximum of 95% of ethanol can be recovered. This
mixture is often referred to as “hydrous sugarcane ethanol” because it
contains 5% water.
SIMULATION:
Now we simulate the process using Aspen Plus and the basic flow chart of
simulation procedure will be as follows:
Fig: Design of ethanol production process
INPUT:
GLOBAL:
TITLE-PROJECT
UNITS OF MEASUREMENT:
INPUT DATA-ENG
OUTPUT RESULTS-ENG
DESRIPTION- PRODUCTION OF ETHANOL
ACCOUNTING:
USER NAME-CHEMICAL
ACCOUNT NUMBER-07842
PROJECT ID-1
PROJECT NAME-ETHANOL
FLOW SHEET:
SECTION-GLOBAL
STREAM CLASS-CONVEN
STREAM CLASS:
AVAILABLE STREAMS- CISOLID, NC, NCPSD, CIPSD
SELECTED SUBSTRAMS-MIXED
SPEICIFICATIONS:
SUBSTREAM NAME: MIXED
TEMPERATURE-250C
PRESSURE-1atm
COMPOSITION-MASS FLOW (TONNE/DAY)
COMPONENT VALUE
DEXTRO-01
WATER
CARBO-01
ETHAN-01
21
79
0
0
FLASH OPTIONS:
MAXIMUM NUMBER OF ITERATIONS: 100
VALID PHASES-VAPOR-LIQUID
ERROR TOLERANCE-0.0001
OPERATING CONDITIONS:
PRESSURE- 2atm
TEMPERATURE- 300C
HOLD UP:
VALID PHASES: VAPOR-LIQUID
SPECIFICATION TYPE: REACTOR VOLUME
REACTOR: 8KL
SEPERATOR SPECIFICATIONS:
STREAM SPECIFICATION: SPLIT FRACTION
SUB STREAM:MIXED
OUTLET STREAM: CO2
COMPONENT ID SPLIT FRACTION
CARBO-01 1
ETHAN-01 0
WATER 0
DEXTR-01 0
COLUMN SPECIFICATIONS:
NO. OF STAGES-20
PRESSURE:
CONDENSER-1atm
REBOILER-1.5atm
KEY COMPONENT RECOVERY:
LIGHT KEY
COMPONENT-ETHAN-01
RECOVERY-0.95
HEAVY KEY
COMPONENT-WATER
RECOVERY: 0.05
REACTION:
TYPE-EQUILIBRIUM
R-1:
DEXTRO-01 2ETHAN-01 + 2 CARBO-01
RESULTS:
ASSUMPTIONS:
1. Let the ethanol content in the beer stream be 11%.
2. As there is no large difference in temperature through out the process,
let it be an isothermal process.
3. Let negligible amount of CO2 is present in ethanol stream and
negligible amount of ethanol in CO2.
DATA SUPPLIED:
INLET STREAM:
Mass flow of glucose=21tonne/day
Mass flow of water=79tonne/day
Temperature=250C
Pressure=1atm
OPERATING CONDITIONS:
P=2atm
T=300C
Volume of reactor=8kl
GAS-LIQUID SEPARATOR:
Split-fraction of CO2=1
DISTILLATION COLUMN:
No. of stages=20
Condenser pressure=1atm
Re-boiler pressure=1.5atm
Key Component recoveries:
Light key component=ethanol
Recovery=0.95
Heavy key component=water
Recovery=0.05
MATERIAL BALANCE:
Mass flow of glucose in=21tonne/day
Mass flow of water in=79tonne/day
Moles of glucose in=W (in g)/GMW = 0.116×106
Moles of water in= 4.388×106
Mole fraction of ethanol=92/180=0.5111
Mole fraction of CO2=88/180=0.4889
Let the weight % of ethanol present in the outlet stream =11
Thus the amount of ethanol present is=100×11/100=11tonne
Mass of ethanol present in the outlet stream =21×0.511=10.731tonne
Mass of CO2 present in the outlet stream=21-10.731=10.269tonne
No. of moles of ethanol=0.2332×106
No. of moles of CO2=0.2333×106
No. of moles of H2O=4.388×106
After the separation of CO2 stream,
the mole fraction of ethanol in the inlet stream to the distillation column
is=0.05042
the mole fraction of water=0.98864
Our aim is to produce 95% of ethanol of weight nearly 10 tonne/day
Writing the material balance to the distillation column,
F=feed=79+10.731=89.731
W=bottom product
D=distillate (or) top product=10.731×0.95=10.19
XF=mole fraction of the feed=0.05042
XD=mole fraction of the distillate=0.95
XW=mole fraction of bottom product
Overall mass balance of the column is
F=D+W
89.731=10.19+W
W=79.541tonne
Writing component balance taking ethanol as basis,
FXF=DXD+WXW
(89.731)(0.05042)=10.19(0.95) +79.541XW
XW=0.0646
Thus the amount of ethanol produced is=10.19tonne/day
Amount of water produced is=74.58tonne/day
Mole fraction of ethanol=0.511
Mole fraction of water=0.488
From the results obtained from Aspen simulation,
The amount of ethanol produced is=10.2tonne/day
The amount of water produced is=75.50tonne/day
Mole fraction of ethanol produced is =0.502
Mole fraction of water produced is =0.49
Hence we can deduce that the results obtained are true and valid.