Dehydration Flashcards
Why is the Dehydration system necessary?
Conventional distillation is limited to an output of 190 proof ethanol. In order to produce pure 200 proof ethanol, water must be further extracted
What are the two basic modes of the Pressure Swing Adsorption (PSA) process?
Dehydration-adsorption under pressure
Regeneration-desorption under vacuum
What type of heat exchanger is the Sieve Feed Economizer?
Plate-and-frame
What is the purpose of Regen Condenser #1 & #2?
Condenses vapors from the Molecular Sieves created during regeneration/sweep cycles
What is the purpose of the Regen Cooler?
Cool Regen Tank Bottoms liquid stream using cooling water
What is the purpose of the Sieve Feed Economizer?
Preheat the 190 proof ethanol before entering the Molecular Sieves
What is the purpose of the 200 Proof Filters?
Removes particulates from the 200 proof final product
What is the purpose of the Regen Tank Bottoms Pump?
Transfer liquid from the bottom of the Regen Tank to the Regen Tank Jet Eductors, Rectifier, and Vacuum Pumps (Seal Water)
What is the purpose of the 200 Proof Product Pump?
Transfer 200 proof ethanol from the 200 Proof Flash Vessel to the 200 Proof Ethanol Storage Tank
What is the purpose of the Steam Condensate Reveiver?
Flashes condensate from the Sieve Steam Condensate Flash Tank to LP steam
What is the purpose of the Sieve Steam Condensate Flash Vessel?
Flashes condensate from the Sieve Vaporizer Condensate Receiver to steam
What is the purpose of the Molecular Sieve Bottles?
Dehydrate 190 proof ethanol to produce 200 proof ethanol
What is the purpose of the Regen Tank?
Collects water that is removed from the molecular beads during the regeneration and sweep cycle
What is the purpose of the 200 Proof Flash Receiver?
Collects 200 proof liquid ethanol condensed in Evaporators #1 and #2
What is the purpose of the 200 Proof Flash Vessel?
Removes carbon dioxide from 200 proof ethanol flowing from the 200 Proof Flash Receiver
What is the purpose of the Sieve Vaporizer Condensate Receiver?
Collects steam condensate from the Sieve Vaporizer and flows to the Sieve Steam Condensate Flash Tank
What does anhydrous mean?
Without water
What state is the 190 proof ethanol when it enter the Molecular Sieve Bottles?
Vapor
What product is heated in the Sieve Feed Economizer?
190 proof liquid ethanol
What product is cooled in the Sieve Feed Economizer?
200 proof liquid ethanol
What is the source of heat in the Sieve Vaporizer?
Medium Pressure Steam (MP Steam)
Where does condensed steam from the Sieve Vaporizer flow to?
Sieve Vaporizer Condensate Receiver
What are the three most important aspects of molecular sieve operation?
Heat, pressure, and vacuum
Which molecular sieve cycle is generally defined by pressurized flow of 190 proof ethanol vapor in which water is removed by the molecular catalyst beads?
Feed Cycle
Which molecular sieve operation is generally defined by a venting of sieve bottle pressure to the 190 Proof Vacuum Condenser?
De-pressure Cycle
Which molecular sieve cycle is generally defined by vacuum being applied to sieve bottles for the purpose of removing entrained water from the molecular catalyst beads followed by a stream of 200 proof liquid ethanol flowing up through the beads to displace remaining traces of water?
Regeneration and Sweep Cycle
Which molecular sieve cycle is generally defined by applying pressure to molecular sieve bottles and an increase in flow of 200 proof liquid ethanol?
Re-pressure Cycle
Where does 200 proof ethanol flow from molecular sieves?
Evaporator #1 or #2
What is the purpose of injecting 200 proof liquid ethanol into 200 proof ethanol vapors?
De-superheat the ethanol vapors
What causes a increase in water content in the 200 proof ethanol vapors during the sweep cycle of the molecular sieves?
Decrease in sweep flow
What is the purpose of the 4 molecular sieve bottle operating cycle valves?
Inlet, de-pressure, regen, and outlet
How is the acidity of ethanol lowered?
Flashing out carbon dioxide
What is the purpose of adding 190 proof ethanol to the 200 Proof Flash Receiver?
Adjust the proof of ethanol (More 190 proof ethanol added to 200 proof ethanol = higher water content)
What does the 200 proof cooler use as a cooling source?
Cooling water
Where is the water that is removed from the molecular catalyst beads collected?
Regen Tank
What is the relation of the Regen Tank contents and the Vacuum Pumps?
Regen is used as seal water for the Vacuum Pumps
What are the 2 sources of vacuum for the Molecular Sieve Bottles?
Regen Eductors
Condensing action of the Regen Condensers
What molecular sieve cycle causes 15% of ethanol feed to molecular sieve bottles to flow to the Regen Tank?
Regen and Sweep Cycle
What 3 places do Regen Tank Bottoms flow?
Regen Eductors
Seal Water Filters (Vacuum Pumps)
Rectifier
What is the purpose of the Regen Cooler?
Removes heat from the Regen Tank Bottoms
What type of heat exchanger is the Sieve Vaporizer?
Shell-and-tube
What occurs when feed temperature to the molecular sieves is out of desired range?
High temperature- Could result in damage to catalyst bed
Low temperature- Condensation of ethanol vapor in molecular sieves and therefore saturation of sieve beads
What is the normal operating temperature range of the 190 proof ethanol vapor flowing from the Sieve Vaporizer?
275-315°F
What occurs when the 190 proof ethanol vapor entering the molecular sieves reaches a low temperature of 260°F?
Interlock will stop the flow of 190 proof ethanol and shut down the molecular sieves
What is the normal operating pressure of the discharge of the Sieve Vaporizer?
45-65 PSIG
What can occur when the Sieve Vaporizer’s pressure is out of range?
Low pressure- Inadequate heat transfer
High pressure- De-pressure into atmosphere via PSV
What Dehydration product is used as a heating source for Evaporator #1 or #2?
200 proof ethanol flowing from Sieve Vaporizer Condensate Receiver
How long is a molecular sieve cycle?
3.5-5.5 minutes
What type of heat exchanger is the 200 Proof Cooler?
Plate-and-frame
What type of heat exchanger are the Regen Condensers?
Plate-and-Frame
What type of exchanger is the Regen Cooler?
Plate-and-Frame
How/why does back pressure (in the molecular sieves) affects the 200 proof product?
Back pressure affects the amount of time ethanol stream is in contact with catalyst beads. Increase in back pressure will increase amount of water removed from ethanol stream.
How is the 200 proof product acidity controlled?
200 Proof Flash Vessel. Carbon dioxide is flashed off and drops carbonic acid content
What equipment in the Dehydration System creates vacuum?
Regen Eductor #1 & #2
What is the purpose of having two Regen Pumps?
Regen Pump #1 is for Sieve Set A
Regen Pump #2 is for Sieve Set B
Why is the regen liquid used for seal water on the Vacuum Pumps?
Vacuum Pumps discharge into the Regen Tank
What are the 2 possible cooling mediums for the Regen Cooler?
Finished Water Tank
Cooling Tower Water
