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IBD General Certificate > Unit 5 - Lesson 3 - Continuous Distilling > Flashcards

Unit 5 - Lesson 3 - Continuous Distilling Flashcards

1
Q

How old is continuous distilling?

A

About 200 years

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2
Q

Who developed continuous distilling?

A

Robert Stain 1827

Aeneas Coffey patented in 1830

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3
Q

Where is continuous distilling used outside of alcohol industry?

A

Chemical process industries for large volumes of liquid distilled into single components or fractions

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4
Q

When to use a continuous still?

A

When very large volumes of wash need to be distilled with requisite recovery of flavor compounds

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5
Q

What type of spirits are produced?

A

Lighter spirits

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6
Q

What are the two main components of a continuous still?

A

Stripping Column

Rectifying Column

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7
Q

Where does feed liquor enter?

A

Middle of the stripping column

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8
Q

What is the thermal source for continuous still?

A

Steam - vaporizing the liquid as it passes up the column to a condenser

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9
Q

What atmosphere do continuous still operate?

A
  1. Normal atmosphere
  2. Higher pressure - higher temps
  3. Vacuum - lower temps
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10
Q

How many plates in a continuous still column?

A

at least 30

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11
Q

What is another name for the stripping column?

A

Beer Column

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12
Q

What does the stripping column do?

A

Strips incoming wash feed of all the alcohol and highly volatile congeners or flavor compounds

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13
Q

What is the main objective of the rectifying column?

A

Concentrate the alcohol and leave stripping column to create final spirits strength

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14
Q

What joins the stripping column and rectifying column?

A

Vapor pipes -

  1. At the top of the Stripping Column to base of rectifying
  2. Another returning liquid to top of stripping column
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15
Q

What is typical of a traditional Coffey Still?

A

Pre-heated wash in the coils of the rectifying column is connected to the top of the stripping column

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16
Q

What is McCabe-Thiele method?

A

Design models calculate number of theoretical plates required for both vapor stripping and rectifying to help design a continuous still

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17
Q

Describe the columns?

A

Rectangle or circular

Stainless or copper or a combo

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18
Q

How to make the still more efficient?

A

Add perforated plates

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19
Q

Advantage of perforated trays in a column?

A
  1. Liquid is retained
  2. Improved vapor/liquid contact - increases separation
  3. Design subject to feed stock
  4. Encourages vapor contact - falling liquid partially vaporizes
  5. Equilibrium involves heat transer
  6. Trays designed to minimize pressure drop
20
Q

What different types of trays are there?

A

Bubble cap trays
Sieve trays
Valve trays
Disc and donut

21
Q

How is heat supplied?

A

Either through steam injected into the column
Or
Reboiler

22
Q

How does steam enter?

A

Steam is injected via a thermo-compressor where live steam supplements steam recovered from boiling liquid leaving the stripping column

23
Q

How does a reboiler work?

A

Takes heat exchanger between liquid from the bottom of the column and live steam

24
Q

Describe a reboiler in more detail

A
  1. Liquid level maintain in base of column, and overflows to reboiler
  2. Heat transfer from live steam converts the liquid to mix of liquid/vapor
  3. This mix fees back into the column above the liquid providing thermal heat to drive the distillation column
25
Q

What is a problem with a reboiler

A

Prone to choking if not maintained and cleaned

26
Q

What are issues with using thermal energy?

A
  1. for steam - it adds volume to the liquid leaving the stripping column as condensation
  2. for Reboilers - prone to failing
27
Q

Points about Thermo Compressor

A
  1. Boiling liquid from stripping column into a vessel to “flash” off liquid creating a vacuum
  2. Vacuum is created by the high pressure steam passing through a Venturi (a pipe connecting to the flash vessel)
  3. Venturi reduces pressure and this steam is sent to stripping column
  4. This process cools the spent liquor and reduces the steam requirement by recovering heat from boiling liquid.
28
Q

What temp does the wash leave the fermentation process in a stripping column?

A

34°C

29
Q

If wash is 34°C before going into stripping column, it requires significant thermal energy to boil. What are some sources?

A
  1. hot vapors from rectifying column
  2. Heat from waste liquor
    KEY IS TO COST EFFECTIVELY DESIGN HEAT RECOVERY SYSTEM for all hot streams
30
Q

How is distillate recovered in a rectifying column?

A
  1. Vapors leave rectifying column
  2. Need to be liquid
  3. Use 1 or 2-stage shell and tub heat exchange
31
Q

What does a higher reflux level mean?

A

Improves separation of high volatile compounds from low volatile compounds

32
Q

What does the column distillation process rely on?

A

Constant supply of wash to the stripping column & continuous removal of distillate and other liquids (eg fusel oils) & Thermal heat eg steam

33
Q

Why do column still require a lot of tanks?

A

For regular accounting of all alcohol products - accurate accountin

34
Q

Describe the basis for a stripping column

A
  1. wash is heated and fed into the stripping column.
  2. feed flows down the column.
  3. highly volatile compounds vaporise and ascend the column.
  4. rising vapour eventually cools, however some of the vapour continues to rise as vapour.
  5. liquid enriched in the less volatile components descends the column.
  6. high volatile products exit the top of the rectification column
  7. low volatility exit from the base of the column.
  8. Steam provided to the base of the stripping column provides the thermal energy to drive the process.
35
Q

What is key for continuous distillation to work?

A

Pre-distillation process have to be robust and produce consistent wash

36
Q

Other names for stripping column?

A

Beer column or Analyzer

37
Q

Where is wash collected

A

wash charger (a still feed tank)

38
Q

What is the typical wash feed temp and ABV?

A

30-34° C

7-14% ABV

39
Q

What happens in a stripping column

A
  1. Wash feed 30-34°C / 7-14% ABV
  2. Heated to 85°C
  3. Waterfalls down stripping column plate to plate
  4. Stillage (spent wash) reaches base of SC
  5. Spent wash through reboiler or thermo compressor then to tanks for processing
  6. Steam/Vapor from either comes in at bottom of SC
  7. Descending wash is progressively stripped of volatiles as steam rises
  8. Vapor/Steam now has the high volatiles leaving the top of the SC
  9. ABV is 10-25% in the vapor
40
Q

What happens in the Rectifying Column

A
  1. least volatile components collect at base (feints)
  2. Feints recycled back to SC to distill again
  3. Liquid collected from Plate near top of RC
  4. ABV 92-96% (impacted by concentration of congeners)
  5. Lower strength more congeners
  6. If product is off - recycled back to SC
  7. Vapors leave RC with high volatiles
  8. Condensed vapors - some to reflux
  9. Remaining vapors “cold feints” and returned
    10 Temp on condenser is controlled to vent unwanted high vols which maxs alcohol recovery
40
Q

What happens in the Rectifying Column

A
  1. least volatile components collect at base (feints)
  2. Feints recycled back to SC to distill again
  3. Liquid collected from Plate near top of RC
  4. ABV 92-96% (impacted by concentration of congeners)
  5. Lower strength more congeners
  6. If product is off - recycled back to SC
  7. Vapors leave RC with high volatiles
  8. Condensed vapors - some to reflux
  9. Remaining vapors “cold feints” and returned
    10 Temp on condenser is controlled to vent unwanted high vols which maxs alcohol recovery
41
Q

Continuous distillation will recover… but not….

A

Ethyl, Butyl and N-propyl
But iso-amyl alcohol

Makes it a light distillation

42
Q

What happens if you dont remove fusel oil?

A

Significant accumulation affecting the character and quality

Very pungent

43
Q

How do you normally remove fusel oil?

A

DECANT
From plates 4-6 fusel oil (iso-amyl) is removed into a decantation tank where alcohol is diluted by water. This separates the fusel oil and forms an oil layer. which is skimmed and stored in tanks

44
Q

What is an alternative process from the decanter to capture fusel oil?

A

Use decanter to

IBD General Certificate (52 decks)

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