An Innovative Solution to Save Energy, Improve Reliability and Reduce Maintenance Cost

Abdulmajeed Alshaye, Saudi Aramco

12/06/2017

Hybrid Instrument Air Dryer

© 2017, Saudi Aramco

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• Objective

• Introduction to IA (instrument air)

• Challenges with the IA system

• High air temperature effect on desiccant dryer

• Hybrid dryer configuration

• Summary

Contents

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To share with you a new concept of compressed air drying:

• Use the minimum amount of energy to operate

• Ensure a constant, low and reliable outlet dew point

• Safe failure mode

• Low maintenance and operation cost

Objective

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Introduction to IA

Unit A

Unit B

Unit C

Unit D

Unit E

Compressor After cooler Separator Wet receiver Pre-filter Dryer

After filter

Dew point Dry receiver Dry receiver

PA

IA

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Introduction to IA

Heat of compression; 80%

[CATEGORY NAME] [VALUE]

[CATEGORY NAME] [VALUE]

[CATEGORY NAME]

10%

1 hp (Final use) 10 hp (Motor) 30 hp (Power plant)

𝜂= 𝐸𝐸𝐸𝐸𝐸𝐸 𝑠𝑠𝑠𝐸𝐸𝑠 𝑖𝐸 𝑐𝑠𝑐𝑐𝐸𝐸𝑠𝑠𝐸𝑠 𝑎𝑖𝐸𝐸𝐸𝐸𝐸𝐸𝐸 𝑖𝐸𝑐𝑖𝑠 𝑖𝐸 𝑠ℎ𝐸 𝑐𝑠𝑠𝑠𝐸

Q. How much compressed air cost us?

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Challenges with IA

• High IA losses (up to 50%)

• High outlet dew point (+70° F)

• Header pressure fluctuation (15%)

• Frequent dryer valves failures

• Condensate drainage

• Portable compressor rental

• Plant safety

• Process interruption

• High maintenance cost

• Less redundancy

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0

2000

4000

6000

8000

10000

12000

14000

Flow

rate

, scf

m

Total production

Total consumption (IA+PA)

Challenges with IA (high losses)

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0

10

20

30

40

50

60

70

۲:۰۰ ۲:۱۰ ۲:۲۰ ۲:۳۰ ۲:٤۰ ۲:٥۰ ۳:۰۰ ۳:۱۰ ۳:۲۰ ۳:۳۰ ۳:٤۰ ۳:٥۰ ٤:۰۰

Dew

poi

nt,

°F

Dew point trend on May 26, 2016, midnight

Challenges with IA (dew point)

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Challenges with IA (pressure swinging)

90

95

100

105

110

۱۳:۰۰ ۱۳:۰٤ ۱۳:۰۸ ۱۳:۱۲ ۱۳:۱۷ ۱۳:۲۱ ۱۳:۲٥ ۱۳:۲۹

Hea

der

pres

sure

(PS

I)

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Challenges with IA (filters damage)

Dryer pre-filter Dryer after filter Dryer after filter Plant instruments

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Challenges with IA (condensate drain)

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High air temperature effect (dryer Inlet)

1. High energy consumption

2. Dryer valve malfunctioning

3. Short desiccant life

4. Filters damage

5. Not meeting IA quality requirement (ISO 8573)

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High air temperature effect (dryer Inlet)

90

100

110

120

130

140

150Te

mpe

ratu

re, °

F

Example for dryer inlet temperature

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27/10/2014 Copyright note text (8pt)

High air temperature effect (dryer Inlet)

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47.1

32.2

24.6

19.61

14.7 11.4

8.4 6.4

4.5 3.4 2.3 1.6 0.0

5.0

10.0

15.0

20.0

25.0

30.0

35.0

40.0

45.0

50.0

۱٥٦ ۱٤۰ ۱۳۰ ۱۲۰ ۱۱۰ ۱۰۰ ۹۰ ۸۰ ۷۰ ٦۰ ٥۰ ٤۰

Wat

er c

onte

nt g

al/h

r

Air temperature in Degree F

Air water content for 5,000 scfm at 132 PSIA

High air temperature effect (Dryer Inlet)

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Hybrid dryer configuration

• This innovative system is relying on two concepts

1. Precooling the compressed air before the desiccant dryer

2. Utilize a external purge heated type desiccant dryer

Working In

Series

Complement &

Independent

Cooling +

Adsorption

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Hybrid dryer configuration

Chilled water

5,000 scfm, 125 psi of compressed air To PA

To IA 250°F 70°F 140°F

250° F

[VALUE]° F

[VALUE]°F 90

47 G/h [VALUE] G/h

[VALUE] G/h [VALUE] G/h 0

50

100

150

200

250

300

Heated desiccant dryer Cyclone 1st aftercooler 2st aftercooler

Air

tem

p. /

wat

er c

onte

nt

Plant cooling water Air compressor

PDP:5°F

1 2 3

86%

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Traditional dryer configuration

• Heatless dryer design

• Purge losses > 20%

• Switching time: 5 minutes

• Valves are prone to failures

• Using single aftercooler

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Hybrid dryer configuration

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• Adsorption dryer and refrigeration dryer

• High capital cost

• High pressure drop

• Low flexibility

Hybrid dryer configuration

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Hybrid dryer configuration (chiller + dryer)

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Hybrid dryer configuration (aftercooler)

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Hybrid dryer configuration (benefits)

1. Reduce the compressed air losses in the utility to less than 2% (now 30-50%).

2. Increase the desiccant dryer switching time from 5 minutes to 48 hours.

3. Significantly improve the quality of the delivered instrument air dew point.

4. Provide dry air for plant air application.

5. Reduce the maintenance cost.

6. Increase instrumentation reliability.

7. Minimize process interruption.

8. Produce pure water as a byproduct.

9. Reduce instrument air pressure fluctuation.

10. Condense the majority of harmful gases in the air.

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Summary

• Compressed air is inherently energy inefficient

• Hybrid dryer design is well suited for hot and humid locations

• Benefits: Energy, Safety, Reliability, Environment, Asset integrity

Availability, Maintenance cost and Compliance

• Flexible operation

• Existing plants or new projects

• Potential energy saving (kingdom): 150 Mw

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Thank you