Literature Survey PresentationEthanol Production • Group # • 1Group #1 • Khalid al-Sulaili 204215889 • Mosleh Mohammed 207217019 • Omar Ali 205112892 • Yousefbahbahani 207111495 • Eid Ali 206113669 • Prof. Mohamed A. Fahim Eng. Yusuf Ismail Ali
Ethanol Production Introduction Histroy Common uses World Production Feedstock Process technology Economic Analysis &Comparison Conclusion
Introduction • The production of renewable fuels such as ethanol has received considerable attention in recent years for its use in automobiles and as a potential source of hydrogen for fuel cells.
WHY ETHANOL? • The environmental deterioration resulting from the over-consumption of petroleum-derived products, especially the transportation fuels. • produce Ethanol from unlimited sources , for example waste gas, such as biogas from landfills, sewage, manure, wood waste, and gasification.
History • Ethanol has been used by humans since prehistory as the intoxicating ingredient of alcoholic beverages. • In 1796, Johann Tobias Lowitz obtained pure ethanol by filtering distilled ethanol through activated charcoal • Ethanol was first prepared synthetically in 1826.
Uses of Ethanol • As a fuel • Alcoholic beverages • Feedstock • Solvent
Ethanol synthesis involves the reaction between CO and H2 (syngas) under high pressures (800 to 2500 psig) and moderate temperatures (180 to 350°C) . • There are several other side products : acetaldehyde, acetic acid and ethyl acetate • The feedstock for this process is syngas which we can produce it by: gasification of solid fuels, such as coal, petroleum coke and biomass, by catalytic reforming of natural gas or by partial oxidation of heavy oils, such as tar-sand oil.
Gasification • steam or oxygen fed to a gasifier at high temperatures (greater than 700°C) to convert carbonaceous biomass into CO, CO2 and H2 . • C + ½O2 → CO ΔH298K = -268 KJ/mol (1) • C + O2 → CO2 ΔH298K = -406 KJ/mol (2) • C + H2O → CO + H2ΔH298K = 118 KJ/mol (3) The water gas shift reaction CO + H2O → CO2 + H2 Due to the combustion reaction CO2 is produced inside the gasifier and for catalytic synthesis, carbon dioxide concentration is usually limited, so it have to be removed.
Gasification Reactors • 1-Counter-current fixed bed (updraft) gasifiers . • 2- Co-current fixed bed (downdraft) gasifiers . • 3- entrained flow gasifiers. • 4- The fuel in a fluidized bed gasifier .
The syngas composition mainly depends upon the type of resources used, their moisture content and the gasification process. • The main reactions are: 2CO(g) + 4H2(g) → C2H5OH(g) + H2O(g) ΔH0298 = −253.6kJ/mol of ethanol ΔG0298 = −221.1kJ/mol of ethanol • The synthesis reaction is exothermic and release a large amount of heat therefore- maintaining constant reaction temperature is an important design consideration- which is removed from the reactor by vaporizing boiler feed water on the shell side of the reactor.
Catalyst • The catalysts can be classified into three categories: modified FTS catalysts, Groups VI-VIII metal-based catalysts and modified ethanol synthesis catalysts. • The catalyst in our process is Rhodium over silica gel (Rh/SiO2 ) . • Rh appears to be one of the most adaptable elements in transition metal series, and tends to yield alcohol synthesis catalysts with high selectivity towards ethanol. • Many materials were formed over each Rh-based catalyst and the amount was in an order of : • Rh/ZrO2 > Rh/SiO2 > Rh/MgO > Rh/CeO2.
Flow sheetand process description • The fresh feed consists of mixture of CO and H2 with: - mass ratio H2:CO equal 2:1. -Total flw rate equal 147032.734 ib/h , temperature =260 F and pressure =2000 psia (stream475) • Then it sent to heat exchanger which raised its temperature to 450 F (stream 512). • Then it sent to the mixed-alcohol reactor which assumed to be a fixed-bed tubular design with steam produced in the shell (E500). • The effluent of the reactor (stream 516) • .Then it sent to air cooler (506) and cooler by cooling water (508) before entering the flash drums, high pressure V-L separator(511).
Cont. • The bottom effluent from the separator sent to low pressure V-L separator (513) and the product from the bottom enter unit 600. • The crude liquid product (stream 528) with total flow rate 74280.2891 Ib/h ,temperature 110 F and 35 psia from the gas/liquid separators is sent to a stabilization column (601) to remove the non-condensable gases, and the gases are sent to the fuel-gas system. • The bottom effluent(stream605) is sent to the heater(621) to vaporized it and sent to molecular sieve drying columns(620) so that all the water is removed. • The dried product stream is condensed by cooler(622) so it enter the second distillation column(MeOH column -610) where 99% of the methanol is recovered overhead at purity greater than 99%.
Cont. • The bottoms product from the methanol column is sent to a second distillation column (EtOH-360) (stream 620) where 99.95% of incoming ethanol is recovered in the overhead stream with total flow rate of 7853 Ib/h ,temperature equal 177 F and a pressure 16 psia (stream 631) where it sent to storage tanks.
Types of Reactors • 1- Tubular fixed bed reactor. )which is in our process)
2-fluidized bed reactor . • 3- Slurry phase reactor where the solid catalyst is suspended in circulating mineral oil.
2- Fermentation -There are many different feed stock for Fermentation to get ethanol. -One of this feed stock is the corn.
production from corn grain involves one of two different processes: Wet milling or dry milling. • Key steps in the dry mill ethanol-production process include: • Milling. • Liquefying and Heating .
Enzyme Hydrolysis. Enzymes are added to break down the long carbohydrate chains making up starch into short chains of glucose and eventually to individual glucose molecules. • Yeast Fermentation. The hydrolyzed mash is transferred to a fermentation tank where microbes (yeast) are added to convert glucose to ethanol and carbon dioxide (CO2).
Distillation. The beer is pumped through many columns in the distillation chamber to remove ethanol from the solids and water. After distillation, the ethanol is about 96% pure. • DehydrationThe small amount of water in the distilled ethanol is removed using molecular sieves. A molecular sieve contains a series of small beads that absorb all remaining water. Ethanol molecules are too large to enter the sieve, so the dehydration step produces pure ethanol .
Process Conditions: • The slurry is “cooked” by using steam at : 4 bar and the process temperature =(110 ◦C)
Reaction and catalyst The yeasts (Saccharomices cerevisiae) catalyse the reaction: C6H12O6→ 2C2H5OH + 2CO2 2C6H12O6+H2O →C2H4O2+2C3H8O3+CH3CH2OH + 2CO2
3-Ethylene dehydration • Feed stock is Ethylene : C2H4 • The reaction :
Operation condition • Ethylene dehydration operates at temperature = 229 c0 and 50 kPa. • Catalyst • Zirconium tungstate
Comparison • -Cost of raw material • Ethylene hydration 1.3$/KG • Fermentation (corn) 12.5$/KG • Syngas 5$/KG - Current capital cost per annual gallon of installed capacity for an ethanol plant ranges from $1.25 to $2.00.
Plant Process cost • Enzyme/FermentationSyngas/Synthesis • Theoretical yield 114 gal/ton 230 gal/ton • Actual yield 70 gal/ton 114 gal/ton • Approx. capital $4.45 $2.33 • cost/gallon/year • Approximate $1.44 $0.78 • cost/gallon
Conclusion • we are not a an agricultural country. • Ethylene comes from fossil fuel. • Syngas can be produced from waste materials that would otherwise need to be discarded. • We recommend the first process: • production ethanol from syngas