Flash Distillation Of d-Limonene In

The Citrus Industry

ICBC Conference 2012

Danny Milla

JBT Corporation

What is d-Limonene?

• d-Limonene is the principal constituent of citrus essential

oils and represents 95% of the essential oil composition

• It is an optically active terpene and is the right-handed

enantiomer of the racemic mixture dipentene

• Dipentene contains both d-limonene (right handed

rotation) and l-limonene (left handed rotation)

• Citrus fruits only produce d-limonene, not l-limonene

• It derives its name from the word “lemon”

Physical Properties

Property Value

Boiling Point 176°C (348°F)

Molecular Weight 136.24 g/mol

Specific Gravity 0.841

Density 7.01 lb/gal

Flash Point 48°C (119°F)

Molecular Formula C10H16

Uses and Applications For d-Limonene

• Industrial cleaning and degreasing

• Adhesive remover

• Circuit board and contact cleaner

• Concrete stain remover

• Imitation spearmint oil (1-carvone)

• Terpene resins for adhesives

• Recycling polystyrene

• Cosmetics and flavorings

Flash Distillation

• Oil bearing emulsion is treated to a high temperature

under pressure and “flashed” into a vapor chamber

• Very high recovery efficiency is possible (>95%)

• Primary operational cost is steam

Flash Distillation

• Why does flash distillation work if the boiling point of d-

limonene is 176°C (348°F)

• Wouldn’t the water boil off at 100°C (212°F) before the

d-limonene boils?

• How do we find the boiling point of a water d-limonene

mixture?

• Enter Dalton’s Law

Dalton’s Law

• States that the total pressure exerted by a gaseous

mixture is equal to the sum of the partial vapor pressures

of each individual component.

or

Where represent the partial pressure

of each component.

• When the vapor pressure of a liquid equals the system

pressure, the liquid will start to boil

• Atmospheric pressure is 760 mm Hg = 29.92 in Hg =

14.7 psi

0

100

200

300

400

500

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800

0 20 40 60 80 100 120

Pre

ssu

re m

m H

g

Temperature oC

Water Vapor Pressure d-Limonene Vapor Pressure

Flash Distillation

• From the previous chart at 97.5°C the sum of the partial

pressures of d-limonene and water is approximately 760

mm Hg (or atmospheric pressure)

• This means that a mixture of water and d-limonene will

start to boil at 97.5°C (207.5°F) until one or the other

of the components is gone

Flash Distillation

• Theory assumes a “perfect liquid”

• In practice, the oil emulsion contains solids, sugars and

pectin that can make d-limonene harder to extract

• Proper system design is required to allow all the d-

limonene to present itself to the surface of the boiling

liquid

Application Scenarios

• There are a variety of ways that flash distillation can be

used to process oil bearing streams

– Replacing cold pressed oil (CPO) systems

– In conjunction with CPO systems

– Feedmill applications

– Waste treatment applications

• The proper application will depend on the particular plant

situation

Application Scenarios – Primary Emulsion

• Recover d-limonene in plants with no cold pressed oil

system or no waste heat evaporator

– Flash distillation can be used in place of centrifuges in

a traditional oil recovery system

– Effluent discharge volume and oil content can be

reduced dramatically

– Total recovery as d-limonene can be up to twice that

collected as traditional CPO

Plant 1 – Case Study Primary Emulsion

• 80,000 MT (~2M 90 lb Boxes) per year of mixed variety

fruits

• The plant has a CPO system that they have not run for

the last four years because of low recovery and high oil

content in the effluent

• The emulsion produced is very high in spun solids which

reduces the efficiency of centrifuges

• Flash distillation unit installed in March of 2011.

Plant 1 – Case Study - Primary Emulsion

• Recovery efficiency from the feed emulsion is typically

over 97%

• 100% recycle, no effluent discharge

• Feed oil content up to 1.8%

• Solids content in the emulsion measured as high as 20%

9/20/2012 17

Plant 1 – Case Study - Primary Emulsion

0

0.2

0.4

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50.00

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85.00

90.00

95.00

100.00

0 5 10 15 20 25 30

% F

eed

Oil

% E

ffic

ien

cy

Efficiency Oil content (%)

Plant 1 – Case Study - Primary Emulsion

0.0

5.0

10.0

15.0

20.0

25.0

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65.00

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100.00

1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22

% P

ulp

% E

ffic

ien

cy

Efficiency Pulp content (%)

Plant 2 – Case Study Primary Emulsion

• 150,000 MT (~3.7M 90 lb boxes) per year of mixed

variety fruits

• The plant also has a CPO system that they have not run

for several years because of low recovery and high oil

content in the effluent

• The emulsion produced is very high in spun solids which

reduces the efficiency of centrifuges

• Flash distillation unit installed in February 2012

Plant 2 – Case Study - Primary Emulsion

• Mandarin fruits

• Recovery efficiency from the feed emulsion is between

98% and 99.2%

• 100% recycle, no effluent discharge

• Feed oil content up to 2.6%

• Solids content in the emulsion measured as high as 29%

9/20/2012 22

Plant 2 – Case Study - Primary Emulsion

Feed Oil % Effluent Oil % % Recovery Centr Pulp % Aldehyde

1.33 .021 98.4% 20 1.23

0.7 .012 98.2% 18 1.22

1.77 .012 99.3% 21 1.19

2.61 .023 99.1% 29 1.40

0.45 .007 98.4% 15 1.32

Application Scenarios – Decant Tank

Overflow

• In a traditional CPO system the heavy phase recycle

water typically overflows the decant tank to reduce the

solids content

• The amount discharged from the decant tank can range

from 15% to 40% of the feed rate, depending on the fruit

variety and maturity

• Depending on the plant, this overflowed water can

discharge to waste or to a waste heat evaporator, if

available

Application Scenarios – Decant Tank

Overflow

• Flash distillation can remove oil from this overflow

stream

• Additionally, the high-oil containing polisher sludge

stream can be fed to the skid transfer tank independently

• The discharge from the skid most likely will not need to

be cooled as it would proceed to the waste system or the

waste heat evaporator

Application Scenarios – Heavy Phase

• For plants who prefer to make CPO, the system can be

used to treat the heavy phase discharge of primary

desludgers and the polisher sludge

• Some plants that do not have waste heat evaporators

must discharge high oil containing streams to their waste

systems

• Removing the d-limonene from the centrifuge heavy

phase can reduce the load on the waste treatment

systems

Application Scenarios – Heavy Phase

• Less oil in the recycle water may improve centrifuge

efficiency

• The system can also perform the duties of the decant

tank

• The exact percentage discharge can be programmed

into the system to maintain desired solids content in the

recycle emulsion to the extractors

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