Ethanol Production Pid

ETHANOL PRODUCTION: THE DRY MILL PROCESS

2013

INTRODUCTION

Ethanol fuel is gasoline mixed with grain alcohol. It is made from grains like corn, wheat and barley. Environmentalists love this fuel because it burns without producing greenhouse gases that are harmful to the environment. By mixing it with gasoline, fuel producers reduce the world's oil consumption.

Ethanol fuel is added into gas in small amounts, as in E10, which is 10 parts ethanol and 90 parts gasoline; it reduces the vehicle's environmental impact and gas consumption. Blends like the E85, which has 85 parts ethanol to 15 parts gasoline, are used primarily by flex-fuel vehicles. The E10 ethanol fuel burns in any car like gas; no engine modifications are needed. Using E85, however, takes a few engine modifications to accommodate the large proportion of the ethanol fuel.

It is well-known that ethanol fuel is made from corn. However, the fuel can also come from wheat, barley, potatoes or sugar cane. Ethanol can't be used for fuel because it is edible. Government regulations prohibit use of edibles for mass fuel consumption. Therefore, the purest type of ethanol is E-95, or anhydrous ethanol. It's 95 percent ethanol and 5 percent gasoline. Next is E85 and E10. Of these types of ethanol, only E10 has been approved for use in all vehicles. Both E95 and E85 require a flex-fuel engine.

Of all the alternative fuels, ethanol fuel has made the biggest splash in recent news. It is a grain alcohol and gasoline blend that is already in use, fueling vehicles across the nation. Although everyone can agree that ethanol is needed to reduce the American dependence on foreign oil. Many people aren't familiar with what ethanol really is, and the controversy behind its use.

ETHANOL PRODUCTION: THE DRY MILL PROCESS

2013

ETHANOL PRODUCTION PROCESS:

Ethanol is commercially produced using either a wet mill or dry mill process. Wet milling involves separating the grain kernel into its component parts (germ, fiber, protein, and starch) prior to fermentation. ICM-designed plants utilize the dry mill process, where the entire grain kernel is ground into flour. The starch in the flour is converted to ethanol during the fermentation process, creating carbon dioxide and distillers’ grain.

Source: http://www. www.icminc.com/ethanol/production_process/

Figure 1: Ethanol Production: Dry Mill Process

ETHANOL PRODUCTION: THE DRY MILL PROCESS

2013

 DELIVERY - STORAGE Grain is delivered by truck or rail to the ethanol plant where it’s loaded in storage bins designed to hold enough grain to supply the plant for 7–10 days.  MILLING The grain is screened to remove debris, then ground into coarse flour.  COOKING (Hot Slurry, Primary Liquefaction, and Secondary Liquefaction) During the cook process, the starch in the flour is physically and chemically prepared for fermentation.  HOT SLURRY The milled grain is mixed with process water, the pH is adjusted to about 5.8, and an alpha-amylase enzyme is added. The slurry is heated to 180– 190°F for 30–45 minutes to reduce viscosity.  PRIMARY LIQUEFACTION The slurry is then pumped through a pressurized jet cooker at 221°F and held for 5 minutes. The mixture is then cooled by an atmospheric or vacuum flash condenser.  SECONDARY LIQUEFACTION After the flash condensation cooling, the mixture is held for 1–2 hours at 180–190°F to give the alpha-amylase enzyme time to break down the starch into short chain dextrins. After pH and temperature adjustment, a second enzyme, glucoamylase, is added as the mixture is pumped into the fermentation tanks.

ETHANOL PRODUCTION: THE DRY MILL PROCESS

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 SIMULTANEOUS SACCHARIFICATION FERMENTATION Once inside the fermentation tanks, the mixture is referred to as mash. The glucoamylase enzyme breaks down the dextrins to form simple sugars. Yeast is added to convert the sugar to ethanol and carbon dioxide. The mash is then allowed to ferment for 50–60 hours, resulting in a mixture that contains about 15% ethanol as well as the solids from the grain and added yeast.  DISTILLATION The fermented mash is pumped into a multi-column distillation system where additional heat is added. The columns utilize the differences in the boiling points of ethanol and water to boil off and separate the ethanol. By the time the product stream is ready to leave the distillation columns, it contains about 95% ethanol by volume (190-proof). The residue from this process, called stillage, contains non-fermentable solids and water and is pumped out from the bottom of the columns into the centrifuges.  MOLECULAR SIEVES The 190-proof product stream is pumped into the molecular sieve system. These specialized tanks contain molecular sieve beads that adsorb water molecules from the process stream while ethanol molecules pass through unaffected. When the product stream leaves the molecular sieves, it contains approximately 99% ethanol by volume (200 proof).  STORAGE AND LOADOUT The 200-proof ethanol is pumped to on-site storage tanks where it is denatured and stored until it is ready to be shipped by tanker truck or rail.  LIQUID - SOLID SEPARATION The stillage from the distillation system is pumped into centrifuges to separate the majority of the solid matter from the solution. This creates two

ETHANOL PRODUCTION: THE DRY MILL PROCESS

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products: A semi-solid product called wet cake is removed and conveyed to rotary dryers. A mostly-water process stream, called thin stillage, is pumped to the evaporation system.  EVAPORATION The thin stillage from the centrifuges is pumped into a series of evaporators where a majority of the water in the solution is removed. The resulting product stream is called syrup. The syrup can be sold as a stand-alone product or added to the wet cake before moving into the dryer system.  DDGS DRYING The wet cake is conveyed to dryers where it is converted into a low-moisture (10-12%) product called dried distillers grains with soluble.

INSTRUMENTATION AND CONTROL In this section Piping and Instrumentation Diagrams (P&ID) shows the ethanol production process, Additional information is shown for the specification of the Process Control and Safety Systems. This P&ID will only concentrate on the ethanol production process only.

ETHANOL PRODUCTION: THE DRY MILL PROCESS

2013

ETHANOL PRODUCTION: THE DRY MILL PROCESS

SYMBOLOGY

PURPOSE

LOCATION

 Converts the reading of the

sensor

standard

into

signal

tank

and

mill;

converts that signal to the weight controller.

REMARKS

 Between the storage

a

and

2013

hammer

 Field (or locally) Mounted Transmitter

 In the make-up water pipeline

before

entering the cooking WEIGHT

slurry tank;

TRANSMITTER

 In the Aplha-amylase pipeline

before

entering the cooking slurry tank; and  In

the

denaturant

pipeline before

 Converts the reading of the

sensor

standard

into

signal

a and

converts that signal to the time controller.

 In the Cooking Slurry Tank;

Mounted

 In the Jet Cooker;  In

the

Transmitter

Secondary

Liquefaction

TIME

 Field (or locally)

Tank;

and

TRANSMITTER

 In

the

Ethanol

Fermentation Tank.

 Receives the data sent by the

pH

trasnsmitter,

compares that data to a programmed and pH INDICATING CONTROLLER

controls

pneumatic valve

setpoint the

 Connected to a pH Transmitter

 Field (or locally) Mounted Transmitter

ETHANOL PRODUCTION: THE DRY MILL PROCESS

 Converts the reading of the

sensor

standard

into

signal

a and

converts that signal to the TEMPERATURE

temperature

controller.

 In the Cooking Slurry Tank; the

Inlet

Transmitter and

Outlet cooling water pipeline

TRANSMITTER

 Field (or locally) Mounted

 In the Jet Cooker;  In

2013

of

Vacuum

the Flash

Condenser;  In

the

Secondary

Liquefaction

Tank;

and  Between the Ethanol Fermentation

Tank

and Distillation Tank

 Converts the reading of the

sensor

standard

into

signal

a and

converts that signal to

 In the Cooking Slurry Tank; and  In

the

 Field (or locally) Mounted

Secondary

Transmitter

Liquefaction Tank;

the pH controller. pH TRANSMITTER

 Receives the data sent by the weight transmitter, compares that data to a programmed set point and WEIGHT INDICATING CONTROLLER

controls

pneumatic valve

the

 Connected

to

Weight Transmitter

a

 Field (or locally) Mounted Transmitter

ETHANOL PRODUCTION: THE DRY MILL PROCESS

 Receives the data sent by the

time

transmitter,

compares that data to a

 Connected

to

a

2013

 Field (or locally)

Temperature

Mounted

Transmitter

Transmitter

programmed set point TIME INDICATING CONTROLLER

and

controls

the

pneumatic valve

 Receives the data sent by the

temperature

transmitter, that

compares

data

to

programmed TEMPERATURE INDICATING

and

 Connected

to

a

 Field (or locally)

Temperature

Mounted

Transmitter

Transmitter

a

setpoint

controls

the

pneumatic valve

CONTROLLER

 Receives the data from the

local

cotrollers,

 Connected to all local controllers

compares that data to a programmed

 Control Panel

Room Mounted

Controller

setpoint

and if necessary controls PROGRAMMABLE

the system.

LOGIC CONTROLLER

 Opens

or

response signals

to sent

controller. PNEUMATIC VALVE

closes

in

control by

the

 Connected to a local controller

 Pneumatically controlled Valve

ETHANOL PRODUCTION: THE DRY MILL PROCESS

 The switch of the  Turns the boiler on and off in response to control signals SWITCH

sent

by

the

closes

in

Electrically Operated

2013

 Electrical Component

Built-in Boiler

controller

 Opens

or

response signals

to sent

control by

 Connected to a local controller

 Electrically controlled Valve

the

controller. VALVE

 A pump is a device used to move fluids.

PUMP

 Between

the

Jet

 Piston

and

the

usually

simple

Secondary

devices

for

Liquefaction tank;

pumping

Cooker

 Between

the

Secondary Liquefaction and

tank Ethanol

Fermentation Tank;  Between the Ethanol Fermentation and

Tank

Distillation

Tank;  Between

the

Distillation Tank and Molecular Sieve; and  After the Denaturant

Pump

-

small

amounts of liquid

ETHANOL PRODUCTION: THE DRY MILL PROCESS

2013

DISCUSSION CHEMISTRY During ethanol fermentation, glucose and other sugars in the corn (or sugarcane or other crops) are converted into ethanol and carbon dioxide. C6H12O6 → 2 C2H5OH+ 2 CO2 + heat Like any fermentation reaction, the fermentation is not 100% selective and other side products such a acetic acid, glycols and many other products are formed to a considerable extent and need to be removed during

the

purification

of

the

ethanol. The fermentation takes place in aqueous solution and the resulting solution after fermentation has an ethanol content of around 15%. The ethanol is subsequently isolated

and

combination distillation

purified of

by

adsorption

techniques.

a and The

purification is very energy intensive. Figure 2: Structure of ethanol molecule. During combustion ethanol reacts with oxygen to produce carbon dioxide, water, and heat: C2H5OH + 3 O2 → 2 CO2 + 3 H2O + heat Starch and cellulose are molecules that are strings of glucose molecules. It is also possible to generate ethanol out of cellulosic materials. However, a pretreatment is necessary that splits the cellulose into glycose molecules and other sugars which subsequently can be fermented. The resulting product is called cellulosic ethanol, indicating its source.

ETHANOL PRODUCTION: THE DRY MILL PROCESS

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Ethanol may also be produced industrially from ethene (ethylene), by hydrolysis of the double bond in the presence of catalysts and high temperature. C2H4 + H2O → CH3CH2OH by far largest fraction of the global ethanol production, however, is produced by fermentation SOURCES Ethanol is a renewable energy source because the energy is generated by using a resource,

sunlight,

which

cannot

be

depleted.

Creation

of

ethanol

starts

with photosynthesis causing a feedstock, such as sugar cane or a grain such as maize (corn), to grow. These feedstocks are processed into ethanol.

Figure 3: Sugar cane harvest, Cornfield in Africa and Switchgrass About 5% of the ethanol produced in the world in 2003 was actually a petroleum product.[18] It is made by the catalytic hydration of ethylene withsulfuric acid as the catalyst. It can also be obtained via ethylene or acetylene, from calcium carbide, coal, oil gas, and other sources. Two million tons of petroleum-derived ethanol are produced annually. The principal suppliers are plants in the United States, Europe, and South Africa.[19] Petroleum derived ethanol (synthetic ethanol) is chemically identical to bioethanol and can be differentiated only by radiocarbon dating.

ETHANOL PRODUCTION: THE DRY MILL PROCESS

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Bio-ethanol is usually obtained from the conversion of carbon based feedstock. Agricultural feedstocks are considered renewable because they get energy from the sun using photosynthesis, provided that all minerals required for growth (such as nitrogen and phosphorus) are returned to the land. Ethanol can be produced from a variety of feed stocks such as sugar cane, bagasse, miscanthus, sugar beet, sorghum, grain, switchgrass, barley, hemp, kenaf, potatoes, sweet potatoes, cassava, sunflower, fruit, molasses, corn, stover, grain, wheat, straw, cotton and other biomass, as well as many types

of

cellulose

waste

and

harvestings,

whichever

has

the

best well-to-

wheel assessment. Currently, the first generation processes for the production of ethanol from corn use only a small part of the corn plant: the corn kernels are taken from the corn plant and only the starch, which represents about 50% of the dry kernel mass, is transformed into ethanol. Two types of second generation processes are under development. The first type uses enzymes and yeast fermentation to convert the plant cellulose into ethanol while the second type uses pyrolysis to convert the whole plant to either a liquid biooil or a syngas. Second generation processes can also be used with plants such as grasses, wood or agricultural waste material such as straw. ETHANOL-BASED ENGINES Ethanol is most commonly used to power automobiles, though it may be used to power other vehicles, such as farm tractors, boats and airplanes. Ethanol (E100) consumption in an engine is approximately 51% higher than for gasoline since the energy

per

unit

volume

of

ethanol

is

34%

lower

than for

gasoline. The

higher compression ratios in an ethanol-only engine allow for increased power output and better fuel economy than could be obtained with lower compression ratios. In general, ethanol-only engines are tuned to give slightly better power and torqueoutput than gasoline-powered engines. In flexible fuel vehicles, the lower compression ratio

ETHANOL PRODUCTION: THE DRY MILL PROCESS

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requires tunings that give the same output when using either gasoline or hydrated ethanol. For maximum use of ethanol's benefits, a much higher compression ratio should be used.

Current high compression neat ethanol engine designs are

approximately 20 to 30% less fuel efficient than their gasoline-only counterparts. Ethanol

contains

soluble

and

insoluble

contaminants.

These

soluble

contaminants, halide ions such as chloride ions, have a large effect on the corrosively of alcohol fuels. Halide ions increase corrosion in two ways; they chemically attack passivating oxide films on several metals causing pitting corrosion, and they increase the conductivity of the fuel. Increased electrical conductivity promotes electric, galvanic, and ordinary corrosion in the fuel system. Soluble contaminants, such as aluminum hydroxide, itself a product of corrosion by halide ions, clog the fuel system over time. Ethanol is hygroscopic, meaning it will absorb water vapor directly from the atmosphere. Because absorbed water dilutes the fuel value of the ethanol (although it suppresses engine knock) and may cause phase separation of ethanol-gasoline blends, containers of ethanol fuels must be kept tightly sealed. This high miscibility with water means that ethanol cannot be efficiently shipped through modern pipelines, like liquid hydrocarbons, over long distances. Mechanics also have seen increased cases of damage to small engines, in particular, the carburetor, attributable to the increased water retention by ethanol in fuel. Ethanol's higher octane rating allows an increase of an engine's compression ratio for increased thermal efficiency. In one study, complex engine controls and increased exhaust gas recirculation allowed a compression ratio of 19.5 with fuels ranging from neat ethanol to E50. Thermal efficiency up to approximately that for a diesel was achieved.[36] This would result in the fuel economy of a neat ethanol vehicle to be about the same as one burning gasoline. Since 1989 there have also been ethanol engines based on the diesel principle operating in Sweden. They are used primarily in city buses, but also in distribution trucks and waste collectors. The engines, made

ETHANOL PRODUCTION: THE DRY MILL PROCESS

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by Scania, have a modified compression ratio, and the fuel (known as ED95) used is a mix of 93.6% ethanol and 3.6% ignition improver, and 2.8% denaturants. The ignition improver makes it possible for the fuel to ignite in the diesel combustion cycle. It is then also possible to use the energy efficiency of the diesel principle with ethanol. These engines have been used in the United Kingdom by Reading Transport but the use of bioethanol fuel is now being phased out. ETHANOL FUEL MIXTURES To avoid engine stall due to "slugs" of water in the fuel lines interrupting fuel flow, the fuel must exist as a single phase. The fraction of water that an ethanol-gasoline fuel can contain without phase separation increases with the percentage of ethanol.[48] This shows, for example, that E30 can have up to about 2% water. If there is more than about 71% ethanol, the remainder can be any proportion of water or gasoline and phase separation will not occur. The fuel mileage declines with increased water content. The increased solubility of water with higher ethanol content permits E30 and hydrated ethanol to be put in the same tank since any combination of them always results in a single phase. Somewhat less water is tolerated at lower temperatures. For E10 it is about 0.5% v/v at 70 F and decreases to about 0.23% v/v at −30 F. FUEL ECONOMY In theory, all fuel-driven vehicles have a fuel economy (measured as miles per US gallon, or liters per 100 km) that is directly proportional to the fuel's energy content. In reality, there are many other variables that come into play that affect the performance of a particular fuel in a particular engine. Ethanol contains approx. 34% less energy per unit volume than gasoline, and therefore in theory, burning pure ethanol in a vehicle will result in a 34% reduction in miles per US gallon, given the same fuel economy, compared to burning pure gasoline. Since ethanol has a higher octane rating, the engine

ETHANOL PRODUCTION: THE DRY MILL PROCESS

2013

can be made more efficient by raising its compression ratio. In fact using a variable turbocharger, the compression ratio can be optimized for the fuel being used, making fuel economy almost constant for any blend. For E10 (10% ethanol and 90% gasoline), the effect is small (~3%) when compared to conventional gasoline, and even smaller (1– 2%) when compared to oxygenated and reformulated blends. For E85 (85% ethanol), the effect becomes significant. E85 will produce lower mileage than gasoline, and will require more frequent refueling. Actual performance may vary depending on the vehicle. Based on EPA tests for all 2006 E85 models, the average fuel economy for E85 vehicles resulted 25.56% lower than unleaded gasoline. The EPA-rated mileage of current USA flex-fuel vehicles should be considered when making price comparisons, but E85 is a high performance fuel, with an octane rating of about 94–96, and should be compared to premium. In one estimate the US retail price for E85 ethanol is 2.62 US dollar per gallon or 3.71-dollar corrected for energy equivalency compared to a gallon of gasoline priced at 3.03-dollar. Brazilian cane ethanol (100%) is priced at 3.88-dollar against 4.91-dollar for E25 (as July 2007). AIR POLLUTION Compared with conventional unleaded gasoline, ethanol is a particulate-free burning fuel source that combusts with oxygen to form carbon dioxide, water and aldehydes. Gasoline produces 2.44CO2 equivalent kg/l and ethanol 1.94.] Since ethanol contains 2/3 of the energy per volume as gasoline, ethanol produces 19% more CO2 than gasoline for the same energy. The Clean Air Actrequires the addition of oxygenates to reduce carbon monoxide emissions in the United States. The additive MTBE is currently being phased out due to ground water contamination, hence ethanol becomes an attractive alternative additive. Current production methods include air pollution from the manufacturer of macronutrient fertilizers such as ammonia. A study by atmospheric scientists at Stanford University found that E85 fuel would increase the risk of air pollution deaths relative to gasoline by 9% in Los Angeles,

ETHANOL PRODUCTION: THE DRY MILL PROCESS USA:

a

very

large,

urban,

car-based

metropolis

that

is

a

2013

worst

case

scenario. Ozone levels are significantly increased, thereby increasing photochemical smog and aggravating medical problems such as asthma. OTHER USES Ethanol fuel may also be utilized as a rocket fuel. As of 2010, small quantities of ethanol are used in lightweight rocket-racing aircraft. There is still extensive use of kerosene for lighting and cooking in less developed countries, and ethanol can have a role in reducing petroleum dependency in this use too. A non-profit namedProject Gaia seeks to spread the use of ethanol stoves to replace wood, charcoal and kerosene. There is also potential for bioethanol replacing some kerosene use in domestic lighting from feedstocks grown locally. A 50% ethanol water mixture has been tested in specially designed stoves and lanterns for rural areas. REFERENCES: http://www.vsep.com/pdf/Ethanol.pdf http://www.eia.gov/biofuels/workshop/pdf/paul_kamp.pdf http://bio-process.com/research/sponsored/

ETHANOL PRODUCTION: THE DRY MILL PROCESS

2013

University of the East College of Engineering Mechanical Engineering Department

P&ID of Ethanol Production: Dry Mill Process

Submitted By:

Submitted To:

Gwyniever Fryce B. Quilantang. 20070153310

Engr. Diosdado Doctor Instructor