Process Technology
Process Technology
Alcohol manufacturing and Natural Gas Sweetening
Kirston Balgobin3-14-2015
TABLE OF CONTENTSAlcohol ProcessingIntroduction3Diagrams
outlining process4-6List of equipment used in process.7Description
of process8-10Conclusion..11Amine ProcessIntroduction.13Diagrams
outlining process.14-16List of equipment used in
process17Description of process.18-19Conclusion20References.21
INTRODUCTION- Alcohol Manufacturing using sugarcane
A distilled beverage, spirit, liquor, or hard liquor is an
alcoholic beverage produced by distillation of a mixture produced
from alcoholic fermentation, such as wine. This process purifies it
and removes diluting components like water, for the purpose of
increasing its proportion of alcohol content. Rum is a distilled
alcoholic beverage made from sugarcane by-products such as
molasses, or indirectly from sugarcane juice, by the process of
fermentation and distillation. It is a spirit drink-:1. obtained
exclusively by alcoholic fermentation and distillation of sugar
cane molasses, sugar cane syrups, sugar cane juices or cane sugar
produced during the processing of sugar cane 2. distilled at an
alcohol content of less than 96.0 percent alcohol by volume at 20
degrees Celsius 3. produced in such a way that the product has the
characteristics derived from the natural volatile elements
contained in the above raw materials or formed during the
fermentation or distillation process of the named raw
materials.There are four major processes involved in making rum;
fermentation, distillation, aging and blending. The basic
principles of rum making are quite simple. The raw materials
required are; a source of cane sugar, water and yeast. The juice of
the mature sugar cane plant or molasses are most commonly used the
raw material for the fermentation process. Fermentation produces
the alcohol and is a spontaneous reaction between the yeast and
sugar .The yeast, is key to the fermentation process as it can
influence the ultimate taste and flavour of the rum. Distilling
separates the alcohol from the fermented mixture and concentrates
it to make the actual rum. Distilling equipment and practice varies
from place to place thus producing rums of different characters.
The standard method used for fractional distillation which can
either be done through batch or continuous distillation. Some
producers work in batches using pot stills however most rum
production is done using column still distillation. Pot still
output contains more congeners than the output from column stills,
so produces fuller-tasting rums. This rum is aged in oak barrels
and ultimately blended to produce the spirit we know as rum. The
golden colour of some rums results from the absorption of
substances from the oak
DIAGRAMS OUTLINING PROCESS
Fig. 1 Block flow diagram of the conventional ethanol production
process from sugarcane.
(http://www.aidic.it/escape20/webpapers/549Dias.pdf)
Fig 2: A simple process flow diagram giving an overview of the
alcohol maufacturing process using sugarcane ( http://galleryhip.c
om/ethanol-production.html)Fig. 2: Diagram of the pot still
apparatus used in batch distillation during the alcohol
manufacturing process ( http://en.wikipedia.org/wiki/Pot_still)Fig.
3: Diagram of the column still apparatus used in continuous or
fractional distillation during the alcohol manufacturing process.(
http://en.wikipedia.org/wiki/Fractional_distillation)Role and
function of the equipment used in the distillation processes of
alcohol manufacturing
The main equipment used in batch distillation of the molasses is
the pot still. Pot Still this is where from which the bottom
product (least volatile, highest boiling point) can be drawn. A pot
still is a type of still used in distilling spirits which consists
of a pot and an outlet to a condenser. It serves as a condenser and
to some extent as a fractionating column. This is used in batch
distillation. The liquid obtained from this type of distillation is
also known as single distillate, since it is processed through the
still only once. Typically this liquid is processed a second time,
thus producing a double distillate which is cleaner and stronger
than the single distillate. Several distilleries have taken this a
step further by running the distillate a third, even a fourth time
through the still, obtaining a cleaner, stronger, more rectified
spirit at the end of each run. Because the amount of liquid that
can be distilled at one time with a pot still is limited to the
size of the kettle, distillers employing this method must perform
their work batch by batch, which is a very labor intensive process
(the kettle must be cleaned in between batches). A basic pot still
consists of three parts:1) the kettle, where the liquid mixture is
boiled2) the condenser, which cools down the vapours coming from
the kettle3) Lyne Arm Transfers the steam to the condenserHowever
the main equipment used in continuous fractional distillation of
the sugarcane molasses is the column still. A column still is a
variety of still consisting of two columns. The continuous
distillation system was created in an attempt to make the
distillation process more consistent. It also reduced the amount of
work required to process each batch, thus allowing for higher
volumes of alcohol to be produced. A distillation column is made up
of a number of horizontal trays placed at different levels
throughout the column. The components used in both continuous and
batch distillation of the molasses are: Condenser Cools the steam
or vapour and produces a pure liquid top product (most volatile,
lowest boiling point). Surge drum Holds the liquid top product and
supplies a steady stream of liquid to the reflux divider Reflex
divider- which splits the top product into two portions. One
portion is taken off as product, the other (called reflux) is sent
back to the top of the column and is processed again. Inlet this is
where the material is processed or fed Steam heater which boils the
liquid in the still Packed column- consists of seven sieve plates
each fitted weir and a downcomer. Description of the alcohol
manufacturing process using sugarcane
1) HARVESTING AND CRUSHING OF SUGARCANERum production begins
with sugar cane. The cut cane is promptly transported to the mill
where it is crushed in a machine. The crushing extracts the sugar
cane juice from the fibrous pulp which is called bagasse. The
bagasse is burned to generate power to crush the cane and sometimes
to heat a distillation column. Depending where you are, the bagasse
can later be burned to generate power or to heat the still.Now that
you have the sugar cane juice, the following can happen: Fermenting
and distilling the sugar cane juice. Understandably, this most
direct approach yields rum that most closely preserves the vegetal
characteristics of the cane. Processing the juice into molasses and
crystallized sugar. The crystallized sugar is sold as a sweetening
product, and the molasses is sold to a distillery to be fermented
and distilled into rum. Most rum is distilled from fermented
molasses.
2) FERMENTATION:Fermentation is a living process. The molasses
is diluted with water to lessen the sugar content to approximately
15% and a yeast culture is added to the mixture. The yeast cells
convert the available sucrose to ethyl alcohol (C2H5OH) and carbon
dioxide (CO2) with the release of heat energy. This mixture is
called the live wash. Fermentation takes roughly 30 hours to be
completed during which time the yeast in the mixture uses up the
available sugar in the molasses. The liquid left at the end of the
fermentation process which is called dead wash is used for
distillation. This reaction occurs in the fermentation
process:C6H12O6 -------- 2CH3CHOH + 2CO2The conditions that produce
fermentation of sugars are: A suitable micro organism, such as
yeast A suitable temperature (30-400C) A small amount of yeast
nutrient such as a phosphate salt Once ethanol concentration
reaches 14-15%, the yeast cannot survive and the fermentation
process stops. The condition under which fermentation of sugars is
promoted is an anaerobic environment operating at about 370C. In
alcohol making, molasses is extracted from sugarcane and mixed with
water, the solution is then clarified to remove excess water. Yeast
is added and the mixture kept in the conditions mentioned before to
be fermented. After the concentration of ethanol reaches about
14-15% the yeast stops producing enzymes because it is being
poisoned by the ethanol. During fermentation, a number of
constituents called congeners are also manufactured. These
congeners, which are regarded as the rum flavours, are the major
constituents of the heavy type rums. They are necessary when
blending because they give flavour and character to the
rum.Congeners formed during fermentation: Aldehydes by oxidation of
alcohol Acids by oxidation of aldehydes Fuel Oil by conversion of
free amino acids in water to higher alcohols Esters by
esterification of alcohols and acids Volatile sulphur compounds by
combination of sulphate and sulphur with amino
acids.DISTILLATION:After fermentation, the fermented wash is fed to
the still where distillation occurs. The distillation process is
done mainly to separate and concentrate the alcohol component of
the liquid mixture. During this process, the undesirable congeners
are removed and the desirable ones that add significantly to the
taste and aroma of the raw rum are retained in the heavy type rum
that is distilled from the first distillation column, There can be
two ways in which a distillation column can operate which is either
as a continuous process or as a batch process. The mixture is
distilled using difference in boiling points (87.30C) for ethanol
that is continuous fractional distillation, by which a 95%
concentrated solution of ethanol is obtained. However in the batch
distillation the mixture is added to the unit at the start of the
distillation, distillate fractions are taken out one after another
during the distillation, and the remaining bottom fraction is
removed at the end. Since each of the distillate exit point is
needed for a batch distillation and the distillate can just be
switched to a different fraction collecting container. Batch
distillation is often used when smaller quantities are distilled.
The distillation process is done mainly to separate and concentrate
the alcohol component of the liquid mixture. During this process,
the undesirable congeners are removed and the desirable ones that
add significantly to the taste and aroma of the raw rum are
retained in the heavy type rum that is distilled from the first
distillation column. This is done by introducing the fermented
liquid mixture into the column at the highest level while steam is
introduced at its lowest level. As the liquid makes its way down
the column, it is heated by the surrounding steam, and the alcohol
on the mix is vapourized. Once it reaches the bottom of the column,
the wash contains no alcohol and is removed through a release
valve. The saturated steam is collected form the top of the column
and is then cooled down, allowing it to condense. Depending on the
type of alcohol desired, column still operators will employ several
columns each one feeding the next, each one producing a cleaner,
stronger more rectified spirit.The purpose of distillation is to
obtain the alcohol from the fermented wash and finally refine it to
produce the spirits that will be used to make the rum. The
fermented wash contains not only alcohol but also many by-products
that as a group are called congeners. These congeners are vital to
the taste and aroma of rum. The first column is the Wash Stripper
or Beer Column; it removes water and residual solids from the wash
stream. The product from this column is heavy rum steam (80-85%
ethanol by vol). This is our first product. It contains all the
congeners from the fermentation. It is very flavourful and aromatic
and it is inevitably aged. To make light, the heavy rum is then
sent to the Purifier (Hydroselector) Column. Here the water added
changes the vapour/liquid equilibrium so that the light components
separate easily from the alcohol. The head goes to the alcohol
recovery column, while the bottoms feeds the Rectifier Column; this
stream is typically 12% alcohol. The rectifier concentrates the
alcohol to be separated; a stream close to the top of the column is
sent for final rectification, the bottoms is recycled to the
purifier and the other cuts are sent to the Alcohol Recovery
Column. This Recovery Column recovers the alcohol from all the
by-product streams from the other columns. The Final Column
produces a bottoms product of 96.6% alcohol (light rum) that may be
used to make rum.BLENDING AND AGING:The light and heavy rums are
aged in oak barrels for periods of not less than two years and up
to fifteen for the heavy rums. The spirits are eventually blended
and sometimes colouring is added. For white rums, the residual
colour from the barrel is actually removed.
CONCLUSION
There are different ways to obtain and produce rum from the
sugar cane. Here are the main steps:1) FermentationSugar cane juice
can be fermented. When this is done, we can obtain what is called
agricultural rum. To obtain industrial rum, molasses or cane syrup
is used. Fermentation lasts about 48 hours, the time needed to
transform the sugar into alcohol. Different yeast are added to the
molasses to accelerate the fermentation process, but also to
improve the aromatic richness of the rum.2) DistillationOnce
fermentation is complete, the molasses is sent into a distillation
column. The molasses is then heated. Since alcohol is more volatile
than water, the alcohol evaporates more easily. The alcohol vapours
floats up the column and condenses in the perforated trays. As they
ascend the column, the vapours become increasingly concentrated in
alcohol. At the top of the column, the rum is finally collected.3)
AgeingAgricultural rum can be called old rum, if it undergoes a
period of ageing of at least three months in oak casks.
THE AMINE PROCESS USED IN NATURAL GAS SWEETENING
INTRODUCTION
Gas sweetening is the process of removing H2S or the sulfur from
natural gas. Sulfur exists in natural gas and is known as hydrogen
sulfide (H2S). Natural gas is usually considered "sour" if the H2S
(hydrogen sulfide) content exceeds 5.7 milligrams of H2S per cubic
meter of natural gas. The H2S removal process from "sour gas" is
commonly referred to as "gas sweetening. Amine gas treating also
known as amine scrubbing, gas sweetening and acid gas removal
refers to a group of processes that use aqueous solutions of
various amines to remove hydrogen sulphide (H2S) and carbon dioxide
(CO2) from gases. It is a common unit process used in refineries
and is also used in petrochemical plants, natural gas processing
plants and other industries. Processes within oil refineries or
chemical processing plants that remove H2S are referred to as the
sweetening processes because the odour of the processed products is
improved by the absence of hydrogen sulphide. The most commonly
used amines in industrial plants are DEA, MEA and MDEA. These
amines are also used in many oil refineries to remove sour gases
from liquid hydrocarbons such as liquefied petroleum gas (LPG). The
primary operation of gas purification processes generally falls
into one of the following five categories:1) Absorption into a
liquid2) Adsorption on a solid3) Permeation through a membrane4)
Chemical conversion to another compound5) CondensationThis gas
sweetening process is vital for removal of contaminants with in the
gas stream which if left in the gas would cause problems with
freezing, corrosion, erosion, plugging, environmental, health and
safety hazards.
DIAGRAMS OUTLINING PROCESSFig 1 showing the operation of a
natural gas sweetening or amine plant
(http://msdssearch.dow.com/PublishedLiteratureDOWCOM/dh_0039/0901b803800391f8.pdf?filepath=gastreating/pdfs/noreg/170-01395.pdf&fromPage=GetDoc)
Fig 2 showing a flow diagram of the gas sweetening process
(http://msdssearch.dow.com/PublishedLiteratureDOWCOM/dh_0039/0901b803800391f8.pdf?filepath=gastreating/pdfs/noreg/170-01395.pdf&fromPage=GetDoc)
Fig 3 showing the operations of a typical amine sweetening plant
(http://www.pall.com/pdfs/Fuels-and-Chemicals/HCP25b.pdf)
Fig 4 showing the steps involved in the gas sweetening process
(http://www.gassweetening.com/)
Fig 5 showing a tray tower absorber Fig 2 showing a flow diagram
of the gas sweetening process
(http://msdssearch.dow.com/PublishedLiteratureDOWCOM/dh_0039/0901b803800391f8.pdf?filepath=gastreating/pdfs/noreg/170-01395.pdf&fromPage=GetDoc)
Role and function of the equipment used in the Amine process for
Natural Gas sweetening
The main equipment used for natural gas sweetening is an amine
plant. Amine plants are used for "gas sweetening" in the midstream
oil and gas sector known as "gas processing." They provide H2S
removal as well as CO2 removal from natural gas and liquid
hydrocarbons. The process involves both absorption and chemical
reactions. The individual roles of the compartments of the amine
plant ensure that the sour gases or contaminants are successfully
removed to ensure no hazards occur. The compartments are:1) Inlet
Separator catches liquid entrainments (water and hydrocarbon
condensate and mist) to prevent entries of contaminants in the
amine system.2) Absorber removes acid gas from feed and operates at
the feed gas pressure.3) Treated Gas KO Drum collects entrained
liquid before being routed to the downstream facilities and dries
the treated gas by removing entrained amine4) Amine Flash Drive
allows the removal of dissolved gas and entrained liquid
hydrocarbons upstream the amine or amine heat exchanger and
generator.5) Amine/ Amine Heat Exchanger- preheats the rich
solution to the regenerator6) Regenerator- regenerates the rich
amine by stripping of the acid gas7) Reboiler- heats up the rich
solution to produce the energy to reverse the chemical reaction to
free acid gas from the amine solution to generate steam to strip
acid gas from solution. The stripping efficiency is controlled by
the overhead reflux. It is essentially a direct fired heater.8)
Reflux drum- catches the possible condensed hydrocarbons so the
water condensed in the condenser is recovered as stripper reflux.9)
Mechanical filter- removes the solids from the amine solution10)
Activated Carbon filter- removes products not stopped by the main
filter.11) Surge tank- spare capacity equivalent to amine solution
hold- up for emergency or maintenance unloading
DESCRIPTION OF THE NATURAL GAS SWEETENING PROCESS
The chemical solvent process, using the various amines, is the
most widely employed gas treating process. These processes utilize
a solvent, either an amine or an alkali-salt (hot carbonate
processes) in an aqueous solution, which reacts with the acid gas
constituents (H2S and CO2) to form a chemical complex or bond. This
complex is then reversed in the regenerator at elevated
temperatures and reduced acid gas partial pressures releasing the
acid gas and regenerating the solvent for reuse.The feed gas (sour
gas) containing H2S and CO2 always must enter the plant through an
Inlet Separator to remove free liquids and entrained solids. The
gas from this separator enters the bottom of the Absorber and flows
upward through the column in a counter current contact with the
aqueous amine solution (lean solution). In the column the chemical
reaction between the amine and the feed gas acid gas occurs and the
amine solution absorbs the acid gas. The chemical gas occurs and
the amine solution absorbs the acid gas. The chemical reaction is
exothermic due to the heat of reaction between the amine and the
acid gas, and it will raise the temperature of the gas.Treated gas
(sweet gas) leaves the top of the column and the amine solution
loaded with acid gas leaves the bottom of the column. The absorber
column operates at the feed gas pressure. A minimum pressure of 4/5
b.a. is required to make the process operable and possible. The top
of the absorber can be equipped with additional trays (2 to 4) to
accommodate a water wash section. The injected water will remove
the amine carried over with the treated gas. It is injected at the
top tray and completely withdrawn at the last tray of the water
wash section. The treated gas is then handled by a separator (or
Treated Gas KO Drum) to collect entrained liquid before being
routed to downstream facilities. The rich solution form the
Absorber is then let down and generally routed to the Amine Flash
drum. This drum allows to remove a portion of acid gas which
changes form the solution by the pressure let-down effect. The acid
gas stream from the Amine Flash Drum is routed either to the fuel
gas pool of the facilities or to the acid gas disposal system. The
rich solution form the Amine Flash Drum then passes through an
Amine or Amine Heat Exchanger. The heat exchanger serves as a heat
conservation device and lowers the total heat requirements for the
process. The rich solution is heated by the regenerated solution
coming from the regenerator. Then the rich solution is let down to
the operating pressure of the Regenerator also called stripper is a
fractionation column (with trays or packing) with a condenser and a
reboiler.The Reboiler can be a direct fired heater. The regenerated
solution from the reboiler at temperatures generally between 1100C
and 1300C, is then routed back to the Amine/ Amine Exchanger. The
top product of the Regenerator is a water vapour or solid gas
mixture. This stream is handled by the condenser where the water
vapour is condensed to produce reflux to the Regenerator. A reflux
drum is provided to collect the condensed water and acid gas
disposal system. Water from the reflux drum is handled by the
Reflux pumps and routed back to the top of the regenerator. The
temperature of the lean solution leaving the Amine Exchanger is
generally still far above the feed gas inlet temperature. Final
lean circulation pumps are provided to cool the solution.
Circulation pumps are provided to send the cooled lean solution
back to the absorber. Acid gas, primarily H2S and water vapour from
the regenerator is cooled in the Amine Regenerator Overhead
Condenser. The mixture of gas and condensed liquid is collected in
the Amine Regenerator Overhead Accumulator. The uncondensed gas is
sent to sulfur Recovery. The Amine Regenerator Reflux Pump pumps
the condensate in the Regenerator Accumulator, mainly water, to the
top tray of the Amine Regenerator. A portion of the pump discharge
is sent to the sour water tank.
Solid impurities such as iron sulphide, iron oxide, sand,
pipeline dust must be removed from the solution in order to prevent
erosion and foaming. The mechanical filter (main filter) is located
on the lean solution stream to the Absorber after the Amine
exchanger. An activated carbon filter can be added downstream of
the main filter to remove products not stopped by the main filter.
An amine storage tank is provided to collect the pure amine or
sweet gas.
CONCLUSION
The Amine process also known as the Gas Sweetening Process can
be summarised through the following steps:1) Sour gas enters the
contactor tower and rises through the descending amine.2) Purified
gas flows from the top of the tower3) The amine solution is now
considered rich and is carrying absorbed acid gases.4) The lean
amine and rich amine flow through the heat exchanger, heating the
rich amine5) Rich amine is then further heated in the regeneration
still column by heat supplied from thereboiler. The steam rising
through the still liberates H2S and CO2, regenerating the amine.6)
Steam and acid gases separated from the rich amine are condensed
and cooled.7) The condensed water is separated in the reflux
accumulator and returned to the still 8) Hot, regenerated, lean
amine is cooled in a solvent aerial cooler and circulated to the
contactor tower completing the cycle.
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