William Grant started his Scottish whiskey distillery in 1887.  Today, this well-known brand has an enviable reputation for the quality of spirits they produce and distribute internationally. Always looking to see how they can improve, they approached Grundfos Pumps to review their energy efficiency. Having undertaken an initial energy check, Grundfos identified several areas where significant savings were possible. Taking the advice offered, two new boiler feed support pumps were purchased, and their performance was measured over a 6-month period.  Results showed electrical savings of £56k pa; the removal of the modulation valve saved £18k per boiler on maintenance costs; a reduction in breakdown and/or steam issues on site; improved steam quality and well as gas savings of up to 9%.

1. Grants Steam Boiler Energy Optimisation Project in partnership with Grundfos

2. The energy centre houses 4 steam boilers:
10 Ton, 12 Ton, 20 Ton and 30 Ton capacity.
Feed pumps are fixed speed Grundfos CR32
(32 Ton Pumps) @ 20 bar, feeding 10 – 30 Ton
boilers at 12 bar including spill back lines,
meaning the pumps are greatly oversized.
Not an uncommon situation in traditional
steam boiler feed applications.
Grants Six Sigma project objective was to
reduce modulating valve maintenance costs.
Grants Steam Boiler Energy Optimisation Project: As is situation
The Girvan site is one of the largest distilleries
in Scotland, producing over 1 million litres of
spirit per year, including Hendricks Gin as well
as the many Grants whisky brands.

3. The Grundfos optimisation team measured, P1 absorbed power, pressure, steam production
and gas consumption across all 4 x boilers, 10 ton boiler No.3 was selected for the trial installation.
Grants Steam Boiler Energy Optimisation Project: System Audit

4. Grants Steam Boiler Energy Optimisation Project: Trial Installation
Utilising the data obtained from the system
audit and previous knowledge of similar boiler
feed applications Grundfos were able to
produce a fully costed proposal to Grants with
predicted electrical energy savings and a
return on investment of less than 2 years.
The proposal included a trial installation and
measurement of Grundfos direct level control
philosophy with variable speed pumps to
replace the existing fixed speed pumps with
boiler level control via modulating feed valve.

5. Deaerator
Feed pumps Gas Burner
Steam Boiler
Bypass Loop
Modulating Feed valve
Level sensor

6. Deaerator
Feed pumps Burner
Boiler
Bypass
Feed valve
Function
In this type of system the water level in the boiler
is controlled by means of a modulating feed valve,
which is controlled by a level sensor output from the boiler.
The modulating feed valve controls the water intake, which is
adjusted according to steam consumption. This, however,
requires that the feed pump is set to “continuous operation”.
Benefits
> Boiler feed water flow adjusted according to
steam consumption.
> Tried and tested method of boiler feed control
Drawbacks
> Bypass excess water
> Feed valve maintenance & replacement is expensive
> Pressure loss across feed valve which leads to
oversized feed pump.
> Slow reaction time to boiler level fluctuations,
inconsistent steam quality

7. Deeper analysis of the data highlighted that flow (blue) far outweighed steam production (orange).
The difference between 32 Ton Feed Pumps and 10 Ton Boiler (22 Tons) is all wasted energy and heat
sent back through the spill back line. In addition as boiler levels are not controlled tightly enough with
the modulating feed valve, carry over occurs degrading steam quality in addition to increasing overall
steam consumption.
Grants Steam Boiler Optimisation Project: System Audit

8. Existing 15 kW Pump for Boiler No.3 replaced
with correctly sized much smaller pump with
11 kW IE5 high efficiency permanent magnet
motor with integrated variable speed drive.
The modulating valve and the bypass
spillback line to the deaerator were removed.
New sliding scale 4-20mA level sensor fitted
Grants Steam Boiler Energy Optimisation Project: The Proposal

9. Deaerator
Feed pumps Gas Burner
Boiler
Level sensor

10. Level sensor min = 4 mA
Low low level = shut down
Low level = 45%, full speed = 11 mA
High level = 55%, pump stop = 13 mA
High High level = shut down
Level sensor max = 20 mA
0
10
20
30
40
50
60
70
80
90
100
4 mA 11 mA 13 mA 20 mA
Motor speed as function of input
Sensor input

11. Purple: Water pressure. Red: Pump speed. Blue: Water level
Difference
between highest
and lowest water
level in boiler is
now only 30mm,
reducing water
carry over and gas
consumption

12. Average 2 – 4% gas saving over a 500 hour period at part boiler load

14. 14
2-4%Gas savings seen when
boilers under constant
level control. Annual gas
spend exceeds £1 million
40%
Electricity savings
seen when constant
level control used
Grants Steam Boiler Energy Optimisation Project: Key Metrics
<£18kOpex cost reduction on
modulating valve repair
and replacement
Scott Curran – Lead Engineer for continuous improvement
‘The amount of improvements we’ve created from such a small
change is pretty extreme, we’re seeing greater energy efficiency
of the boiler, reduced gas usage and steam quality is better.
No failure rates and they’ve been running for six months, no
problems whatsoever’

15. Summary of Key Takeaways
> Elimination of modulating feed vales and associated maintenance / replacement costs
> Reduction in electrical energy consumption
> Reduction in gas consumption
> Improved level control within the boiler, leading to improved boiler efficiency
> Reduced water carry over, leading to: Improved steam quality
Improved thermal heat transfer
Reduced levels of condensate
Reduced levels of ‘water hammer’
Improved down stream process stability

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