Development of a generic bioprocess flowsheet model for Life Cycle - - PowerPoint PPT Presentation

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Development of a generic bioprocess flowsheet model for Life Cycle studies

KG Harding, JS Dennis, STL Harrison

SLIDE 2

Bioprocess Engineering Research Unit 2 University of Cape Town

Introduction

To assess economic or environmental performance of a process, we need to know:

The raw material requirements per unit product (material balance) Equipment size The energy requirements (energy balance)

This requires a process flowsheet Engineering flowsheeting packages are often:

Complex Data intensive Time consuming to set up Expensive, and Need validation

A simplified first estimate allows input for early decision making

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Bioprocess Engineering Research Unit 3 University of Cape Town

Introduction

A simplified first estimate allows input for early decision making We report on a generic bioprocess flowsheet model to provide such a first estimate To demonstrate, we use two case studies

Pencillin Cellulase

SLIDE 4

Bioprocess Engineering Research Unit 4 University of Cape Town

Bioprocess flowsheet DSP Product formation

SLIDE 5

Bioprocess Engineering Research Unit 5 University of Cape Town

Inputs & Outputs – Product formation

Decisions

How much product do you want? How much biocatalyst (micro-organism or enzyme) do you need? Micro-organism as product, intra- or extracellular product? Aerobic or anaerobic process? Continuous, batch or fed-batch process?

Product formation

Raw materials: C- (x2), N- (x2), O- (aerobic), P- & S- sources (excess?) Product spectrum: Biomass, 1° metabolite, 2° metabolite

SLIDE 6

Bioprocess Engineering Research Unit 6 University of Cape Town

Key parameters – Product formation

Gas compression (aerobic)

1 or 2 stage compression, pressure, Cooling water temp, efficiency

Yield coefficients

YX/S, YP/S, YX/O

Metabolic parameters

Maintenance coefficients, cell concentrations, growth rate

Sterilisation

• Temp. (steam, sterilisation, reactor, cooling water,…), Efficiency, Pressure

Agitation

Number of tanks, power per unit volume, tank & impeller geometry

Reactor control

Antifoam, reactor cooling, water used (distilled, deionised, municipal)

SLIDE 7

Bioprocess Engineering Research Unit 7 University of Cape Town

Bioprocess flowsheet DSP

SLIDE 8

Bioprocess Engineering Research Unit 8 University of Cape Town

Key parameters –Liberation & S/L separation

Centrifugation / washing

Energy per unit volume, No of centrifuge/wash cycles, Efficiency

Filtration

Pressure gradient, Efficiency, Filter area, Flocculent, Filter media (type, height, voidage, density…)

Sedimentation

Flocculent (Percentage added, density, composition)

High pressure homogeniser, Ball mill, Cavitation

Extent of cell disruption, Energy efficiency,

SLIDE 9

Bioprocess Engineering Research Unit 9 University of Cape Town

Key Parameters – Concentration & Purification

Adsorption (efficiency, pressure gradient, cross sectional area) Centrifugation (as before) Evaporation (temperatures, efficiency) Decanter (efficiency, pressure gradients, cross sectional area) Filtration (as before) Precipitation (temperature, precipitation agents, power input, efficiency) Solvent extraction (efficiency, pressure gradient, cross sectional area, solvent, phase splits) Splitter (split fraction)

SLIDE 10

Bioprocess Engineering Research Unit 10 University of Cape Town

Key Parameters – Formulation

Oven drying

Temperatures, Efficiencies

Freeze drying

Temperatures, Reduced pressure, Vacuum inlet area, Efficiencies

Spray Drying

Temperatures, Humidities

SLIDE 11

Bioprocess Engineering Research Unit 11 University of Cape Town

MS-EXCEL Screenshot

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Bioprocess Engineering Research Unit 12 University of Cape Town

Example Flowsheet: Cellulase

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Bioprocess Engineering Research Unit 13 University of Cape Town

Input assumptions: Cellulase

Assumptions Scenario H1 Units Extracellular, aerobic product produced in a batch reactor Cooling water temperature 25 °C Chilled water temperature 5 °C Max temperature difference between exiting cooling water and hot inlet streams 10 °C Microbial growth conditions (batch production from Trichoderma reesei) Product: Biomass ratio 0.89

• Carbon 1 source (excess): Cellulose

10 % Carbon 2 source (excess): Corn liqor 33.3 % Mass percentage Carbon 2 as total carbon 14.38

• Nitrogen source 1: Ammonia

% Nitrogren source 2: Nutrients 33.3 % Mass percentage Nitrogen 2 as total carbon 80.2

• Excess Air

2500 % Maintain rector temperature (Cooling agent: Chilled water) Initial cell concentration (into fermenter) 0.76 g/l Initial cell concentration (whole process) g/l Final cell concentration 15 g/l Aeration Compressed pressure 608 kPa Compressor efficiency 0.7

• Steam Sterilisation (Cooling agent: Cooling water)

°C 110 Preheated temperature °C 140 Sterilisation temperature °C 152 Steam temperature °C 35 Outlet temperature/Reactor temperature H 8 Sterilisation time % 81 Liquid (waste) removed % 98 Solids (product) retained Ultrafiltration M2 39.95 Cross sectional area % 100 Liquid retained % 100 Solids removed Rotary vacuum filter kW/m3 0.5 Power per unit volume

• 3

Height /Daimeter (fermenter) h 121.25 Residence time Agitation Units Scenario H1 Assumptions

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Bioprocess Engineering Research Unit 14 University of Cape Town

Mass balance results: Cellulase

In (kg) Out (kg) In (kg) Out (kg) Heinzle et al. (2006b) Scenario H1 Ammonia 0.082 0.00 0.096 0.00 Trichoderma Reesei 1.17 0.06 1.15 Carbon Dioxide 1.48 3.63 Cellulase 0.041 0.020 Cellulose 3.62 0.32 3.57 0.26 Corn liquor 0.61 0.12 0.73 0.15 Enzyme 14.9 15.6 Nutrients 0.33 0.065 0.52 0.10 Oxygen (reacting O2 only)

• 2.94

Water 73.3 59.9 74.9 61.8 TOTAL 77.9 77.9 82.8 82.8 Product recovery (% kg cel) 96.1 98.0 Energy requirements Heinzle et al. (2006b) Scenario H1 Units Electricity 38.6 42.2 kWh/kg cel. (MJ/kg cel) Steam (152 °C, 3 bar) 4.74 4.62 kg/kg cel. (MJ/kg pen) Chilled water 0.84 0.56 m3/kg cellulase Cooling water 2.62 5.23 m3/kg cellulase Component

SLIDE 15

Bioprocess Engineering Research Unit 15 University of Cape Town

LCA Comparison: Cellulase

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Bioprocess Engineering Research Unit 16 University of Cape Town

Example Flowsheet: Penicillin

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Bioprocess Engineering Research Unit 17 University of Cape Town

3 sets of input assumptions: Penicillin

Assumptions Scenario 1 Scenario 2 Scenario 3 Units Extra cellular, aerobic product produced in a batch reactor Cooling water temperature 5

• °C

Max temperature difference between exiting cooling water and hot inlet streams 20

• °C

Stream Sterilisation Reactor temperature 32

• °C

Microbial growth conditions (batch production of Penicillin from Penicillium chrysogenum) Product: Biomass ratio 1.2 1.2 1.2

• Carbon 1 source (excess): Glucose

2

• %

Carbon 2 source (excess): Phenoxyacetic acid 1.7

• %

Mass percentage of carbon source 2 as total carbon 10.6 10.6 10.6 % Nitrogen source (excess): Pharmamedia (C55.7H6.7O18.9N16S2.7 (Phyllis 2006)) 14.6

• %

Sulphur source excess

• Oxygen source (excess): Air

1450

• %

Compression: Single stage reciprocating compressor, 601.03 kPa compressed press.. Maintenance coefficient 0.022 0.022

• h

Time for over which maintenance is considered 106 106

• h

Final cell concentration 45 45

• g/l

Yield coefficients: Yx/s 0.45

• g/g

Yp/s 0.81

• g/g

Yx/o 1.56

• g/g

Agitation (11 tanks) Residence time 156.3

• h

Power per unit volume 2.5 2.5

• kW/m3

Efficiency 1

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Bioprocess Engineering Research Unit 18 University of Cape Town

3 sets of input assumptions: Penicillin

Assumptions Scenario 1 Scenario 2 Scenario 3 Units Post fermentation cooling Outlet temperature 28

• °C

Filtration Solid fraction removed 100

• %

Liquid fraction removed 91 91

• %

Additive: Sulphuric acid 0.028 0.028 0.028 %v/v Centrifugation Solid fraction removed 98

• %

Liquid fraction removed 91.8 91.8

• %

Energy per unit volume 3060

• kJ/m3

Additive: Butyl acetate (assumed no recycle) 9.2 9.2 9.2 %v/v Additive: Sodium hydroxide 0.25 0.25 0.25 %v/ Reaction: Sodium hydroxide + Sulphuric acid Sodium sulphate + Water (conversion: 97 % limiting reagent) Precipitation/Crystallisation Outlet temperature 6

• °C

Residence time 12

• H

Power per unit volume 0.6

• kW/m3

Additive: Acetone 12.3 12.3 12.3 %v/v Additive: Sodium acetate 7.8 7.8 7.8 %v/v Reaction: Sodium acetate + Penicillin Acetic acid + Penicillin V sodium crystals (conversion: 97 % limiting reagent) Centrifugation Solid fraction removed 99

• %

Liquid fraction removed 97.9

• %

Fluid bed drying (Electricity: 72.2 MJ/m3) Product fraction removed 99

• %

Liquid fraction removed 90

• %

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Bioprocess Engineering Research Unit 19 University of Cape Town

3 sets of input assumptions

Post fermentation cooling Outlet temperature 28

• °C

Filtration Solid fraction removed 100

• %

Liquid fraction removed 91 91

• %

Additive: Sulphuric acid 0.028 0.028 0.028 %v/v Centrifugation Solid fraction removed 98

• %

Liquid fraction removed 91.8 91.8

• %

Energy per unit volume 3060

• kJ/m3

Additive: Butyl acetate (assumed no recycle) 9.2 9.2 9.2 %v/v Additive: Sodium hydroxide 0.25 0.25 0.25 %v/ Reaction: Sodium hydroxide + Sulphuric acid Sodium sulphate + Water (conversion: 97 % limiting reagent) Precipitation/Crystallisation Outlet temperature 6

• °C

Residence time 12

• H

Power per unit volume 0.6

• kW/m3

Additive: Acetone 12.3 12.3 12.3 %v/v Additive: Sodium acetate 7.8 7.8 7.8 %v/v Reaction: Sodium acetate + Penicillin Acetic acid + Penicillin V sodium crystals (conversion: 97% limiting reagent) Centrifugation Solid fraction removed 99

• %

Liquid fraction removed 97.9

• %

Fluid bed drying (Electricity: 72.2 MJ/m3) Product fraction removed 99

• %

Liquid fraction removed 90

• %
• 1

Efficiency kW/m3

• 2.5

2.5 Power per unit volume h

• 156.3

Residence time Agitation (11 tanks) g/g

• 1.56

Yx/o g/g

• 0.81

Yp/s g/g

• 0.45

Yield coefficients: Yx/s g/l

• 45

45 Final cell concentration h

• 106

106 Time for over which maintenance is considered h

• 0.022

0.022 Maintenance coefficient Compression: Single stage reciprocating compressor, 601.03 kPa compressed press.. %

• 1450

Oxygen source (excess): Air

• Sulphur source excess

%

• 14.6

Nitrogen source (excess): Pharmamedia (C55.7H6.7O18.9N16S2.7 (Phyllis 2006)) % 10.6 10.6 10.6 Mass percentage of carbon source 2 as total carbon %

• 1.7

Carbon 2 source (excess): Phenoxyacetic acid %

• 2

Carbon 1 source (excess): Glucose

• 1.2

1.2 1.2 Product: Biomass ratio Microbial growth conditions (batch production of Penicillin from Penicillium chrysogenum) °C

• 32

Reactor temperature Stream Sterilisation °C

• 20

Max temperature difference between exiting cooling water and hot inlet streams °C

• 5

Cooling water temperature Extra cellular, aerobic product produced in a batch reactor Units Scenario 3 Scenario 2 Scenario 1 Assumptions

3 sets of input assumptions: Penicillin

%

• 90

Liquid fraction removed %

• 99

Product fraction removed Fluid bed drying (Electricity: 72.2 MJ/m3) %

• 97.9

Liquid fraction removed %

• 99

Solid fraction removed Centrifugation Reaction: Sodium acetate + Penicillin Acetic acid + Penicillin V sodium crystals (conversion: 97% limiting reagent) %v/v 7.8 7.8 7.8 Additive: Sodium acetate %v/v 12.3 12.3 12.3 Additive: Acetone kW/m3

• 0.6

Power per unit volume H

• 12

Residence time °C

• 6

Outlet temperature Precipitation/Crystallisation Reaction: Sodium hydroxide + Sulphuric acid Sodium sulphate + Water (conversion: 97 % limiting reagent) %v/ 0.25 0.25 0.25 Additive: Sodium hydroxide %v/v 9.2 9.2 9.2 Additive: Butyl acetate (assumed no recycle) kJ/m3

• 3060

Energy per unit volume %

• 91.8

91.8 Liquid fraction removed %

• 98

Solid fraction removed Centrifugation %v/v 0.028 0.028 0.028 Additive: Sulphuric acid %

• 91

91 Liquid fraction removed %

• 100

Solid fraction removed Filtration °C

• 28

Outlet temperature Post fermentation cooling

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Bioprocess Engineering Research Unit 20 University of Cape Town

MS-EXCEL Screenshot

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Bioprocess Engineering Research Unit 21 University of Cape Town

Mass balance results: Penicillin

Component In (kg) Out (kg) In (kg) Out (kg) In (kg) Out (kg) In (kg) Out (kg) Heinzle et al. (2006) Scenario 1 Scenario 2 Scenario 3 Acetic acid

• 0.17
• 0.17
• 017
• 0.17

0.31 1.17 0.25 6.89 0.04

• 0.47

1.00 0.03 0.07 0.01 0.12 0.04 0.25 0.01

• 0.20

70.79 Acetone 0.12 0.12 0.22 0.22 0.22 0.22 0.31 Biomass (dry cell weight)

• 0.88
• 0.90
• 0.90
• Butyl acetate

0.32 0.32 0.18 0.18 0.18 0.18 0.25 Carbon dioxide

• 5.47
• 6.58
• 7.29
• Glucose

5.10 0.10 5.18 0.06 5.56 0.03 5.47 Oxygen (excl. excess & N2) 2.56

• 4.01
• 4.54
• 4.02

Penicillin V (loss)

• 0.10
• 0.14
• 0.14
• Penicillin V sodium salt
• 1.00
• 1.00
• 1.00
• Penicillin V sodium salt (loss)
• 0.03
• 0.03
• Pharmamedia

0.47 0.06 1.30 0.17 1.19 0.06 1.54 Phenoxyacetic acid 0.60 0.01 0.39 0.04 0.41 0.00 0.53 Sodium acetate 0.23 0.01 0.26 0.03 0.26 0.02 0.36 Sodium sulphate

• 0.00
• 0.01
• Sodium hydroxide

0.12 0.12 0.11 0.10 0.11 0.10 0.27 Sulfuric acid 0.01 0.01 0.01 0.01 0.01 0.00 0.04 Trace metals 0.77 0.10

• Sulphur source /SO2 (out)
• 0.32

0.15 0.33 0.15 0.43 Water 19.2 21.1 19.1 21.3 18.88 21.4 68.64 Energy requirements Heizle et al. 2006 Scenario 1 Scenario 2 Scenario 3 Units Electricity 23.04 22.25 19.39 21.25 kWh/kg penicillin Steam 1.26 3.3 3.4 10.11 kg/kg penicillin Total energy equivalent 86.38 89.01 78.98 103.80 MJ/kg penicillin Chilled water 3.32 1.05 1.27 1.90 m3/kg penicillin Cooling water 1.17

• m3/kg penicillin

SLIDE 22

Bioprocess Engineering Research Unit 22 University of Cape Town

LCA Comparison: Penicillin

SLIDE 23

Bioprocess Engineering Research Unit 23 University of Cape Town

LCA Process contributions: Penicillin

SLIDE 24

Bioprocess Engineering Research Unit 24 University of Cape Town

LCA Process contributions – Eutrophication (kg PO4

3- eq.)

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Bioprocess Engineering Research Unit 25 University of Cape Town

Conclusions

A generic flowsheet has been developed for bioprocess systems Gives first estimate mass and energy balance data

Fast, minimal inputs Can be used by non-engineers/scientists

Good approximation of results to existing data This data can then be used for further analyses

Environmental Economic

Valuable to determine ‘hotspots’

SLIDE 26

KW Johnstone Scholarship National Research Foundation Technology and Human Resources for Industry Programme (THRIP)