Producing deaerated water Methods, design considerations and operational implications

John Kyle Dorton Competence Center Manager

Thermal & Process Modules

Alfa Laval Copenhagen A/S

• Uses of deaerated water in the brewing process

• What is and why use deaerated water

• DAW production methods

• Operational & design considerations

• Maintenance & cost of ownership

2

Agenda

Uses of deaerated water in the brewing process

3

Brewhouse

Mashing Lautering

Boiling Clarification Cooling

Fermentation &

yeast

handling

Propagation & storage

Thermolysing

Beer

recovery

Aeration &

pitching Fermentation & maturation

Yeast

recovery

Filtering

Blending &

carbonation

Clarification Cellar

Dewatering

De-alcoholization Packaging

Pasteurisation

Sterile filtration

Deaeration

CIP

Utility

cooling

4

Brewing process

Image courtesy of Alfa Laval Copenhagen A/S

5

Primary uses of deaerated water

Blending

& dilution Filtering

Beer chasing

Pasteurizer

recirculating

Fermenter chasing

Wort

chasing

Mashing in

Stripping

Steam

generation

Filling

& packing

CIP

Beer

Clarification

What is and why use

deaerated water

6

7

What is deaerated water?

2

Water

Typical

water

Dissolved

gasses

2

2

Dissolved

gasses

2

2

8

What is deaerated water?

2

Water

Deaerated

water

(DAW)

9

Why use DAW?

Flavour changes

+

Haze formation

+

Shelf life issues

+

… 2 Beer

10

Why use DAW?

Oxide degradation

+

Acid corrosion

+

Steam line

degradation

+

…

2

2 Image courtesy of Alfa Laval Copenhagen A/S

Boiler

11

Why use DAW?

Photos sourced from http://www.gewater.com/handbook/boiler_water_systems/fig11-5.jsp (accessed October 9 ,2013);

http://www.i-chemsolution.com/boiler-water.html (accessed September 5, 2013)

Oxide degradation

+

Acid corrosion

+

Steam line

degradation

+

…

DAW

production methods

12

13

A bit of theory

f(pressure,

temperature,

gas partial pressure)

Henry’s law of partial pressures

p = kH ∙ c

p is the partial pressure of O2 in vapor phase

kH is Henry’s constant (Temperature dependent)

c is the concentration of O2 in liquid

Dissolved

Air

2

2 2 2

p → c

Δ pressure

t → kH → c

Δ temperature

cgas1 → clighter gas 2

Δ gas

14

Trivia: how much O2 in water?

O2 N2

Molar wgt 31.99 28.01 g∙mol-1

fpartial fraction of air 0.21 0.79

temperature 77 … F

pressure 1 … atm

kH 769.2 1639.3 atm∙mol-1∙liter

c = M∙f∙p / kH 0.0087 0.0134 g∙liter-1

Dissolved

Air

2

2 2 2

Approximately ~8.7 ppm (v/v)

Δ p

ressure

Δ t

em

pera

ture

Δ g

as

Pros Cons

Boiling Simple & easy High thermal energy use

Low DO level Risk of O2 pickup

15

Deaeration techniques

Vacuum stripping DO < 0.5 ppm High vacuum required

H2O prone to O2 pickup

Vacuum stripping DO ~ 0.5 ppm Carrier gas lost

and gas injection High energy use

Catalytic reaction Very low DO Use of H2 requires

using H2 special installation

provisions (ATEX)

Δ p

ressure

Δ t

em

pera

ture

Δ g

as

Pros Cons

Ambient stripping Robust Influenced by gas purity

while injecting CO2 or N2 DO < 0.01 ppm Affected by temperature

Low energy use

Strip gas retention (Strip gas retention)

16

Deaeration techniques

Stripping + vacuum Redundancy Strip gas lost

using CO2 or N2 DO < 0.01 ppm Moderate energy use

Sensitivity to vacuum

Ambient injection Simple Slow

using CO2 or N2 DO < 0.02 ppm Influenced by gas purity

Strip gas retention Batch production only

Δ p

ressure

Δ t

em

pera

ture

Δ g

as

Double-vessel vacuum system at ambient temperature

17

Industrial scale methods <0.05 ppm

Mass transfer through perforated trays using

low pressure steam

stripping

(desecrating heaters)

Images sourced from http://www.spx.com/en/apv/pd-mp-deaerators-derox/;

http://www.gkmoss.com/index.php/cat/deaerators/page/traydeaerators (accessed September 5, 2013)

Δ p

ressure

Δ t

em

pera

ture

Δ g

as

Mass transfer through

membranes combining

gas stripping & vacuum

& variable temperature

18

Industrial scale methods <0.01 ppm

Mass transfer through

packed vessel at

ambient pressure &

variable temperature

Top image sourced from http://www.centec.de/en/products/food-beverages/dgs-membran.html (accessed September 5, 2013);

Bottom image courtesy of Alfa Laval Copenhagen A/S

Δ p

ressure

Δ t

em

pera

ture

Δ g

as

Gas injection into vented vessel at

ambient pressure and

temperature

19

Batch method <0.02 ppm

Images courtesy of Alfa Laval Copenhagen A/S

Operational & design

considerations

20

Beverage applications

<0.5 ppm

21

What DO level do I need?

Beer applications

<0.02 ppm

Boiler systems

<0.01 ppm

Images courtesy of Alfa Laval Copenhagen A/S

22

Packed vessel stripping basics

Water

feed

Stripping

gas

Ambient

stripping

vessel

(column)

DAW

Vent

Pack

elements

Fluid

distributor

• Large surface area to volume ratio

• Perforated, cross-patterned packing

• Interrupted flow paths (no bypass ports)

• Counter flow arrangement

• Stripped gas vents from top

• Stripping gas flow required is just above

the solubility level

23

Impact of gas purity on stripping

Water

feed

Stripping

gas

Ambient

stripping

vessel

(column)

DAW

Vent

CO2 34.7 Nm3/h

~0.3 Nm3/h O2

+1.7 Nm3/h CO2

+ other residuals

Purity ≥ 99.9%

Fluid

distributor

Water 8.7 ppm O2

450 hl/h, 25C

DAW ~1452 ppm CO2

~0.041 ppm O2

≥ 99.99%

Water 8.7 ppm O2

CO2

DAW ~1452 ppm CO2

~0.004 ppm O2

O2 + CO2

+ other residuals

Higher

purity

↓

Lower DO

>95% of

stripping

gas is

retained

24

Influence of stripping temperature

Water

feed

Stripping

gas

Ambient

stripping

vessel

(column)

DAW

Vent

Fluid

distributor

Stripping height

decreases …

with

increasing

temperature

21.7

19.0

17.7

14.8 14.8

24.6

21.7

19.0

14.8 14.8

43 54 77 122 162

Str

ipp

ing

he

igh

t (f

t)

Stripping temperature (F)

O2 <

0.0

2 p

pm

O2 <

0.0

5 p

pm

25

Feed water quality

Free of

particles

50 to 77F (10 to 25oC)

Clear &

purified

26

Feed water quality

If like this … then expect this Images courtesy of Alfa Laval Copenhagen A/S

Design considerations

DAW

buffer

Water feed

Inlet

balance

tank Stripping

gas

Carbonation

Filter

Steam

Cooling

Stripping

column

DAW • Stripping gas

type?

• Ambient or hot? • Vessel height

constraints

• Bacteriological

treatment

• Pasteurization

or UV

• Media availability

• Additional carbonation? • High gravity blending

• DAW

cooling?

• Inlet balance tank? • Mitigate varying inlet pressure

• Need for local CIP

Pros Cons

Tailored Exacting KPIs Longer lead times

stripping vessel Specific conditions Longer commissioning

Specificity of spares

28

Tailored vs. pre-configured systems

Pre-configured Short lead times Fixed capacity intervals

stripping vessel Cost effective Condition invariance

(inlet temperature & pressure)

Commonality of spares

Images courtesy of Alfa Laval Copenhagen A/S

Maintenance and

cost of ownership

29

30

Indexed relative running costs

0.5

1.0

1.5

2.0

2.5

3.0

3.5

4.0

4.5

Boiling Packed

vessel

stripping Ambient

pressure &

high temperature

Vacuum

+ gas

stripping High

temperature

0

Packed

vessel

stripping Ambient

pressure &

temperature

Vacuum

stripping Ambient

temperature

DAW with

0, 2 and 5 g∙l-1 CO2

5.0

Base cost

Packed vessel < 0.001 0.018 (0.015) 1.06 (0.41)

stripping 5 min 2.2 lbs (1 kg)

Ambient startup per start

pressure &

Temperature

31

Normalized utility usage (77F)

Vacuum stripping 0.014 0.035 (0.03) 1.22 (0.47)

using membranes ≤ 213 bbl (250 hl) ~25 min 66.2 lbs (30 kg)

Ambient temperature per start; startup per start

4.4 gpm (10 hl∙h-1)

sealing H2O

Batch stripping - 0.062 (0.053) 1.29 (0.5)

Start after < 2.2 lbs (1 kg)

tank is filled per start

Condition

272.7 bbl (320 hl)

2.2 hours stripping

DO ~0.02 ppm

CO2 purity 99.99%

2 g∙l-1 carbonation

Conditions

596 bbl∙h-1 (700 hl/h)

Water at 77F (25oC)

DO ~0.005 ppm

CO2 purity 99.99%

4 g∙l-1 carbonation

kW∙bbl-1

(kW∙hl-1)

Electricity

2

bbl∙bbl-1

Water

lbs∙h-1∙bbl-1

(kg∙h-1∙hl-1)

Gas

2

32

Increment for cooling & heating

DAW cooling - + 10.69 (2.67) + 0.011 (0.009)

inlet water 77F (25oC) outlet 36F (2oC)

DAW heating + 2.35 (0.91) + 12.89 (3.22) + 0.021 (0.018)

& cooling 162F (72oC) outlet 36F (2oC)

inlet water 77F (25oC) 90% regeneration

lbs∙h-1∙bbl-1

(kg∙h-1∙hl-1)

Heating (steam)

Recirculation - - + 0.028 (0.024)

of cooling media

to prevent water

freezing

kW∙bbl-1

(kW∙hl-1)

Electricity

mBTU∙h-1∙bbl-1

(kW∙hl-1)

Cooling

33

What if feed water is colder (68F)?

DAW cooling - + 8.37 (2.09) + 0.011 (0.009)

inlet water 68F (20oC) outlet 36F (2oC)

DAW heating + 2.61 (1.01) + 10.79 (2.69) + 0.021 (0.018)

& cooling 162F (72oC) outlet 36F (2oC)

inlet water 68F (20oC) 90% regeneration

lbs∙h-1∙bbl-1

(kg∙h-1∙hl-1)

Heating (steam)

kW∙bbl-1

(kW∙hl-1)

Electricity

mBTU∙h-1∙bbl-1

(kW∙hl-1)

Cooling

More heating…

but less cooling

34

Maintenance expectations

Packed vessel 3-4 Pump seal changes (annual)

stripping Valve seal changes (annual)

CO2 purity checks (≤ semi-annual)

Vacuum stripping 5-8 Vacuum pump seal changes (≤ annual)

using membranes (periodic Membrane changes (≈ 4-5 years)

increases) Valve seals changes (annual)

CO2 purity checks (≤ semi-annual)

Batch stripping 1-3 Nozzle integrity (annual)

Vessel seal (≤ semi-annual)

hrs∙year-1 Tasks

35

CIP requirements

Packed vessel Prior to start Water sterilization (> 200F, 95oC) after stop (>12 hr)

stripping ≤ Weekly Standard CIP recipe (flush–caustic–flush)

Monthly Acid cleaning

Vacuum stripping Prior to start Water sterilization (< 176F, 80oC) after stop (>12 hr)

using membranes ≥ Weekly Membrane flushing with purity CIP recipe

Batch stripping Prior to batch Standard CIP (locally mixed) (if infrequent)

Frequency Type

Closing remarks

36

• Uses of deaerated water in the brewing process

• What is and why use deaerated water

• DAW production methods

• Operational & design considerations

• Maintenance & cost of ownership

37

Closing remarks

38

Ask a brewer, “why DAW?”

Stable flavour

profiles

+

Less haze

formation

+

Improved

shelf life 2 Beer

John Kyle Dorton

Alfa Laval Copenhagen A/S johnkyle.dorton@alfalaval.com

+45 27778521