optimizing continuous deodorization for quality...

Optimizing Continuous Deodorization for Quality and Energy

Jim Willits, Sr. ConsultantDesmet Ballestra North [email protected]

Update on New Technologies and Processes in Oils and Fats

106th AOCS Annual Meeting

Brief Deodorization History

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History of Deodorization

Pre-deodorization

• Oil chosen for how it smelled, tasted, and its consistency, durability and availability

• The demand for a extender for butter/lard resulted in the development of margarine, which in turn created the need to be able to reduce the flavor in available oils and fats.

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1850s

• First patents on atmospheric, directly heated, no sparge gases and carbon steel construction

1890s

• First batch deodorizers with sparge gasses and direct heat. Still carbon steel construction

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1920s

• French engineers added:

• Vacuum

• Higher temperatures

• Non-oxidizing materials of construction

• There was a need developing in the US to replace animal fat in shortening with cottonseed oil

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1920s

• David Wesson developed a deodorizer which used:

• Indirect heat

• High temperature under vacuum

• This unit offered capability to reduce the strong flavor of cottonseed oil

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c.1948

• Around 1948 the Girdler/Votator Companies developed a true Semi Continuous Deodorizer

• A. E. Bailey developed a deodorizer with vertical stacked trays that could hold very good vacuum in the presence of sparge steam

• Dowtherm was introduced which allowed indirect heating with a low pressure vapor

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• Benjamin Thurman of Humko Products developed a deodorizer with seven horizontal cylinders (four to deodorize and three for cooling)

1960s

• Votator developed the steam lift pump which allowed the use of deeper trays and reduced the deodorization time from 90 minutes to 30 minutes

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1970s

• Simon-Rosedowns introduced the thermosyphon, which offered the ability to exchange heat within the deodorizer vessel

• The growing palm oil industry gave rise to the continuous deodorizer

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1970s

• Frank Sullivan developed scrubbers to remove fatty material from the vapor stream

• P & G developed thin film strippers

1980s

• Alfa Laval championed the use of packed columns in palm oil deodorization

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1990s

• Desmet brought the ice condensing vacuum system into the market, which allowed economical low vacuum

• High pressure steam started to replace terminal and Dowtherm as heating media for deodorization

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2010s

• Desmet Ballestra adds flexibility to generation of hot water for sharing the BTU’s generated in deodorization with other refinery and seed preparation processes.

• Improvements made in the recovery of Tocopheral as price's for this products increase significantly.

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Deodorization Equipment

R&D

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Bench/Pilot/Full Scale

“Science behind Technology”

Objectives of Deodorization

Deodorization is a crucial refining stage with a big impact on the refined oil quality. Its has three main objectives:

1. Stripping of volatile components such as free fatty acids (in case of physical refining), valuable minor components (tocopherols, sterols, etc.) and contaminants (pesticides, light PAH, etc.);

2. Actual deodorization by removal of different off-flavors;

3. Thermal destruction of pigments (so-called heat bleaching).

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Factors Affecting Oil Quality

• Seed Variety

• Growing Conditions

• Harvesting Conditions

• Extraction Conditions

• Degumming and Neutralizing

• Bleaching

• Deodorizing

• Storage

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Factors Affecting Deodorizing Quality

• Temperature

• Time

• Pressure

• Steam rate

• Air Leaks

• Heating and Cooling under vacuum

• Quality of incoming oil

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Selection Process

• We start with 3 base deodorizer designs:

→ Continuous flow

→ Continuous flow – Packed Stripper

→ Semi-continuous flow

• From these three base designs, we add options to meet specific needs

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Three Base Deodorizer Designs

• Qualistock+TM

• Qualistock+ FSTM

• MultistockTM

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Deodorizer Designs: Qualistock+

• Continuous flow deodorizer

• Deodorization in trays (deep or shallow)

• Up to three stock changes per day

• Ideal for internal oil/oil heat recovery

• Internal spray/packing vapor scrubber

• Low-temp, long-time deodorizing, or

• High-temp, short-time deodorizing

• High-Low or Low-High temp deodorizing

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Qualistock + New Configuration

• All major sections combined into single vessel

• Reduced losses and improved distillate quality

• Splash oil eliminated

• Low energy consumption

Deodorizer Designs: Qualistock+ FS™

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• Continuous flow deodorizer

• Fatty acid stripping in packing, then deodorization and heat bleach in tray

• Up to three stock changes per day

• Ideal for internal oil/oil heat recovery

• Internal packing-type vapor scrubber

• Popular for palm/soy/canola physical refining

• Popular in North America for high-temp, short deodorization-time, soy/canola oil deodorization

Deodorizer Designs: Qualistock+ FS™

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Deodorizer Designs: Multistock™

• Semi-continuous flow deodorizer

• Deodorization in deep tray (s)

• Multiple stock changes per day(10 or more possible)

• Minimum stock change contamination

• Thermosyphon heat recovery (Single or Double)

• Internal or external spray vapor scrubber

• Popular at multiple feedstock plants

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Deodorizer Designs: Multistock™

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Deodorizing Options

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Deodorizing Options: Packed Columns

• Utilizes very high surface area of structured packing to create a thin film for excellent steam stripping

• Minimizes time at high temp for heat sensitive oils

• Allows high or low tocopherol stripping (soy)

• Deodorizing steam can be re-used for stripping

• Insufficient time, if used alone, to remove less volatile compounds

• Insufficient time, if used alone, for thorough heat bleaching

• Pressure drop needs to compensated in scrubber and vacuum system design

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Deodorizing Options: Packed Columns

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Deodorizing Options: Deep Trays

• Utilize steam lift pumps to continuously expose a thin film of oil to the vacuum

• Excellent steam stripping mechanism

• Long residence time for removing less volatile compounds that reduce oil stability

• Long residence time for heat bleach effect

• Most cost effective residence time

• Long residence time can increase trans formation

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Deodorizing Options: Deep Trays

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Deodorizing Options: Shallow Trays

• Utilizes sparge steam pipes to regenerate the surface in contact with vacuum

• Multiple shallow trays can add residence time for removing less volatile compounds that reduce oil stability

• More shallow trays are more expensive than fewer deep trays

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Deodorizing Options: Shallow Trays

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Deodorizing Options:

Dual-Tem ® Packing/Tray High-Low

• Packing section operates at high temp (500°F) and tray operates at low temp (446°F) after a quick quench

• Minimizes trans fatty acid formation

• Provides high tocopherol removal (soy)

• Reduced heat bleach effect

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Deodorizing Options:

Dual-Temp® to reduce trans fatty acids

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220230

240250

2600 minutes

10 minutes

20 minutes

30 minutes

0

0.2

0.4

0.6

0.8

1

1.2

1.4

1.6

%Trans isomer

Temperature deg C

Time

FORMATION OF TRANS ISOMERS IN SOYBEAN OIL AT DIFFERENT TEMPERATURES

Deodorization Conditions

Conditions Chemical Physical

U.S. Europe Europe

Temperature (°C) 245-260 230-240 230-250

Pressure (mbar) 2-3 2-3 2

Sparge steam (%) 0.5-2.0 0.5-1.0 1-2

Time (min) 20-40 40-60 60-90

Final FFA (%) 0.03-0.05

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Chemical versus Physical Refining

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Pressure Stripping Steam Booster Steam Fuel

Booster Deodorizer (kg/tone oil) (kg/tone oil) (kg)

Chemical Refining

2.5 mbar 3 mbar 10 45 4.23

1.5 mbar 2 mbar 7 43.4 3.88

Physical Refining

2.5 mbar 3 mbar 20 90 8.46

1.5 mbar 2 mbar 15 93 8.31

Heat Recovery Options

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Heat Recovery Options: Oil/Oil Internal

• Used with continuous deodorizers

• Excellent heat recovery (80-90%)

• Heat exchange under vacuum

• Reduced installation cost

• No need for an outside heat sink

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Heat Recovery Options: Oil/Oil Internal

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Heat Recovery Options: Oil/Oil External

• Used with continuous deodorizers


• No need for an outside heat sink

• Shorter stock change time (1 hour)

• Potential oxidation of oil (not under vacuum)

• Higher installation & maintenance costs

• Less of a “turn down” potential

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Heat Recovery Options: Oil/Oil External

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Plate-type

Huge Shell & Tube-type

Heat Recovery Options:

Thermosyphon (single or double)

• Used with semi-continuous deodorizers

• Simple – no pumps required

• No external heat sink required

• Single has low heat recovery (single: 40- 45%)

• Double has medium heat recovery (double: 60-65%)


• Rather high capital cost for heat exchanged

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Heat Recovery Options:

Thermosyphon (single or double)

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Heat Recovery Options

Low Pressure Steam Generation


• Produce heat recovery oil/oil (high-low dual-temp quench)

• Produce 30 psig steam after thermosyphon


• Good heat recovery (80-85%)

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Heat Recovery Options: Hot Water Generation


• Produce 195 °F water for heating tanks, boiler feed water, seed heating


• Requires a hot water utilization system

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Vapor Scrubbing Options

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Vapor Scrubbing Options:

External Spray Contact

• Low fatty acid carry-over

• Minimizes deodorizer tower height

• Works with any deodorizer design

• Requires expensive external ducting and added installation cost

• Increase in size of vacuum system due to increased pressure loss

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Vapor Scrubbing Options:

External Spray Contact

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water

LC

Fatty

acids

Scrubber

Vacuum

unit

Booster steam

Vapor Scrubbing Options: Internal Spray


• Eliminates expensive external ducting and installation cost

• Works well at the base of the deodorizer

• Increases deodorizer tower height

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Vapor Scrubbing Options: Internal Spray

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814

823

FAD

FA Scrubbing Demister

Vacuum connection

Vapor Scrubbing Options: Internal Packing


• Eliminates expensive external ducting and installation cost

• Works well at the top of the deodorizer

• Increases deodorizer tower height

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Vapor Scrubbing Options: Internal Packing

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1 5 0 m m

5 7 5 m m

1 5 . 0 0 °

Deodorizer Distillates

Composition Chemical Refining Physical Refining

Neutral Oil 25 - 33% 5 – 10%

Fatty Acids 33 – 50% 80 – 85%

Unsaponifiable matter 25 – 33 % 5 – 10 %

6 – 15% 2 – 5 %

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Tocopherols

Tocopherols / Sterol Recovery

Vacuum System Options

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Vacuum System Options:

Dirty Water / Steam Jet System

• Least expensive initial cost

• Optimizes cooling water temperature

• High motive steam (approx. 9:1 ratio)

• High waste water discharge

• Dirty cooling water – fouling & odor problem at tower

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Dirty Water / Steam Jet System

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Clean Water / Steam Jet System

• Relatively low initial cost

• Clean cooling water – little fouling or odor

• Cooling temperature higher than cooling water

• Highest motive steam (approx. 10:1 ratio)

• Highest waste water discharge

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Clean Water / Steam Jet System

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Chilled Water / Steam Jet System

• Reduced motive steam (approx. 5:1 ratio)

• Reduced waste water discharge

• No ammonia required

• Additional energy to chill water

• Higher initial cost

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Chilled Water / Steam Jet System

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Sublimax® Ice Condensing System

• Very low operating pressures made practical

• Motive steam reduced below 1:1 ratio

• Lowest net operating energy

• Lowest waste water volume

• Low ammonia hold-up in patented Sublimax ® system

• Higher electrical power for ammonia compressor

• Highest initial cost

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Compressor

Condenser

Separator

Cooling waterFrom FA scrubber

Vapour (vacuum)

Refrigerant (ammonia)

Non-condensable gases

Valve, closed

Valve, open

Melt vessel

Condensate

Tode-aeration

Freezecondenser

waterprocess vapor ammonia

LP steam


Sublimax® Ice Condensing System

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Update on New Technologies and Processes in Oils and Fats

106th AOCS Annual Meeting

Thank you for your attention!

Jim Willits, Sr. ConsultantDesmet Ballestra North [email protected]

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