crystallizer

CRYSTALLIZATION UNIT Rachel Adams Jana Dengler Megan MacLeod Kyla Sask CHEE 450: Insulin Design Project

Outline Purpose of Crystallizer Methods of Crystallization Design Specifications Engineering Drawing Alternative Cost and Suppliers Alternative Processes Questions

CRYSTALLIZATION UNIT

Outline Purpose of Crystallizer Methods of Crystallization Design Specifications Engineering Drawing Alternative Cost and Suppliers Alternative Processes Questions

CRYSTALLIZATION UNIT

Purpose of Crystallizer Used to recover pure solids from solution Highly desirable end product because of: ± Exceptional purity ± Ease of handling ± Long shelf life

One of the final treatment steps in the purification and concentration of insulin 98% of the insulin must be crystallized CRYSTALLIZATION UNIT

Mechanism of Crystallization Crystal

nucleation and amorphous precipitates are in competition during supersaturation conditions

Nucleation favored by slowly exceeding the equilibrium point of saturation ± permits time for the protein structure to orient in a crystalline lattice

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Continuous or Batch Design Benefits of Continuous ± ± ± ±

Can

maintain solution in supersaturated state Large fluidized bed for crystallization Minimizes operation costs Minimize down time (startup and shutdown)

Benefits of Batch

± Good when have low concentration of product, high viscosity or many impurities ± Can produce high quality crystal CRYSTALLIZATION UNIT

Methods of Crystallization Supersaturation: liquid (solvent) contains more

dissolved solids (solute) than can ordinarily be accommodated at that temperature

Can

± ± ± ±

be achieved by several methods:

Cooling

Evaporation Solvent addition Precipitant Addition CRYSTALLIZATION UNIT

Cooling Method Concentrated

solution gradually cooled below saturation temperature (50-60°C) to generate a supersaturated state Yields well defined micron-sized crystals Shell and tube heat exchanger is used to cool solution CRYSTALLIZATION UNIT

Cooling Method Advantages:

± High purity downstream

Disadvantages:

± Temperature change does not always have a positive effect on supersaturation in proteins ± Protein stability may be at risk ± Solubility can be relatively insensitive to temperature at high salt concentrations ± Cooling will only help reach supersaturation in systems where solubility and temperature are directly related CRYSTALLIZATION UNIT

Evaporation Method Solute dissolves in solution when heated to a certain temperature (75°C) Slowly cooled until crystals precipitate Shell and tube heat exchanger is used to heat and cool solution

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Evaporation Method Advantages:

± high purity levels downstream

Disadvantages:

± Vaporization chamber requires high pressure ± Protein viability very sensitive to high temperatures

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Solvent Method Solvents are generally good protein precipitants Their low dielectric constants lower the solvating power of their aqueous solutions Requires acidic solvent ± For crystallization, an insulin protein falls out of solution at isoelectric point pH 5.4-5.7

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Solvent Method Advantages:

± Proteins viability not at risk due to temperature change

Disadvantages:

± Possible protein contamination due to insufficient downstream solvent recovery

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Addition of Zinc Ions In the presence of zinc ions, insulin proteins orient to form hexamer structures Zinc ions render insulin insoluble which results in micro-crystallization and precipitation Human Insulin Hexamer with Zinc ion

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Seeding Techniques Primary nucleation is the first step in crystallization - growth of a new crystal

± Can bypass primary nucleation (creation of new crystals) by "seeding" the solution

Secondary nucleation is crystal growth initiated by contact

± Accelerated by "seeding" adding existing insulin crystals to perpetuate crystal growth CRYSTALLIZATION UNIT

Progression of Crystallization

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http://www.cheresources.com/cryst.shtml

Crystal Size and Growth Rate Crystal

size distribution is important for the production process; affects: ± downstream processing ± solids transport ± caking and storage properties of the material

Correct

crystal size vital for economic production Crystals produced in commercial crystallization processes are usually small ± 30 to 100 um in diameter

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Crystal Size and Growth Rate Assumptions:

Crystal Area : A c

± Continuous ± Constant-volume ± Isothermal ± Well-mixed

Crystal Mass : M c !

no exp

Mechanism of crystal growth dL to determine crystal growth dt

k k s a

Relates population density and crystal size

n

!

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3k v V

L

/G X

c cs

k a L2

! !

Vk v L

3

Crystallizer Design Addition of acidic solvent to decrease pH to achieve supersaturation Addition of Zinc ions to initiate Insulin precipitation Implementing of ³seeding´ technique Minimize heat variation to maintain protein stability Washing and extensive solvent recovery downstream CRYSTALLIZATION UNIT

Design Equations Crystal quantity ! retentiontime flowrate Slurry quality ! crystalquantity/0.25 Specificgravity of slurry Volume

V

!

H

!

T

D

!

2

4 2.5D

!

sg of solution 0.25 sg of solutio

quality of slurry 6.24 specificgravity of slurry

H

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sg of crystals 0.75 sg of crystals

Proposed Design Temperature

25 °C

Pressure

1.013 bar

Flowrate

111.842 kg/batch

Volume

0.29 m3

Diameter

0.529 m

Height

1.325 m

Residence Time

23.98 h

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Engineering Drawing

http://sundoc.bibliothek.uni-halle.de/diss-online/04/04H181/prom.pdf CRYSTALLIZATION UNIT

Costing Estimates Three costs involved: ± Crystallizer unit ± Zinc Chloride Solution and Water ± Power Requirements

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Costing Estimates Crystallizer Unit

www.matche.com

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Costing Estimates Crystallizer Unit atch, tmospheric Crystallizer

80000 70000 60000 50000 40000 30000 20000 10000 0 0

0

0

0

0

0

0

1

1

1

1

Size (m3) Ca bon S ee Sane CRYSTALLIZATION UNIT

S ee

1

1

1

Costing Estimates Zinc Chloride Solution

± Many suppliers ± $15.00 - $27.00 for 500g

Power Requirements ± Canadian Hydro: 8.99 cents/kWh (April, 2006) CRYSTALLIZATION UNIT

Crystallizer Suppliers GEA Niro Inc. ± ±

Companies

in over 50 countries Copenhagen, Columbia, Germany, USA GEA Kestner Evaporator/Crystallizer

Swenson Technology Inc. ± Illinois, USA

HPD Inc.

± Illinois, USA

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Alternative Processes For special drug purposes and when a zinc-free product is needed Alternative processes that can be used include: ± Isoelectric Precipitation ± Gel Chromatography ± Ultrafiltration

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Isoelectric Precipitation Protein purification procedure that can be used with crystallization or on its own

The pH of a mixture is adjusted to the pI of the protein to be isolated to selectively minimize its solubility CRYSTALLIZATION UNIT

Gel Filtration Chromatography Molecules are separated according to their size and shape Filtration column is filled with porous beads Solution passes through column Elution through the gel occurs in order of decreasing molecular masses CRYSTALLIZATION UNIT

Ultrafiltration Ultrafiltration used to concentrate macromolecular solutions Forced under pressure or by centrifugation through a semipermeable membranous disk Solvent and small solutes pass through the membrane, leaving behind a more concentrated macromolecular solution CRYSTALLIZATION UNIT