The document discusses the problems caused by water contamination in heat transfer fluid systems, particularly those operating at sub-zero temperatures. It introduces a range of mobile and fixed fluid drying units that can reduce water content in heat transfer fluids down to 10 parts per million while the systems are in continuous operation. The drying units work by stripping water from the fluid using nitrogen or through distillation processes. Examples are given of drying cycles that have reduced water levels in large systems significantly.

1. TECHNICAL ISSUE 2
Is the water in your Sub Zero
Heat Transfer Fluid System costing
you Money?
Water causes extensive plant reliability problems and is a
major cause of plant failure and production loss. Synthetic
fluids are used as a heat transfer medium at temperatures
down to –100°C and up to 400°C and water causes
problems through the whole range. Sub zero systems are
particularly susceptible to problems.
In order to reduce system water content, we have
designed a range of mobile and fixed drying units
based on ‘nitrogen stripping’ and ‘distillation’ principles.
The units can dry fluid down to below 10 parts per
million while in continuous production at Sub Zero
Mobile drying unit
temperature or in stand alone batch processing.
The range of heat transfer fluid
dryers are ideally suited for the Recent example Recent example
following situations: System Content: 175 000 litres of Dowtherm J Water removed: 148.75 Litres
Drying cycle: 24 days (16hours per day) Water content: 407 ppm dried to 27.38 ppm.
At Commissioning:
To dry the system following system Water removal from 407ppm to 27.38 = 66.43 Litres
installation or modification. PPM Overall system water removal
Inlet to rig ppm estimated at 148.75 litres
Start ppm Finish ppm Diff ppm
During plant operation: 500 Outlet from rig ppm 407.00
285.00
148.30
148.80
258.70
136.20
149.00 82.50 66.50
To trim water levels without stopping Rig operated 16 hrs per day 120.10 55.40 64.70
Rig off
Rig off
99.00 85.00 14.00
63.25 50.33 12.92
production. 400 * System content 175000
56.50
55.85
25.90
50.20
30.60
5.65
Litres 36.17 26.40 9.77
31.16 16.46 14.70
In emergency: 27.38 23.31 4.07
Following accidental water ingress 300
or heat exchanger failure.
Variations were caused by chiller cycling
* and opening of sub loops
*
Stock fluids: 200
Stand alone batch drying of ‘wet’ fluids. *
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Permanent Installation: 100
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Dedicated to one or more process plants. * *
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Mobile Units: * *
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1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25
For operation on several plants as well Days
as standby for emergencies.

2. The Problem How does water get in? Services:
Saturated nitrogen used for blanketing. We
New Systems:
The water saturation point of heat transfer have experienced systems where 30% water
New systems, extensions and alterations not
fluids varies with the fluid type and the was found after a heat exchanger failure,
being sufficiently dried at commissioning.
operational temperature. with a complete plant closure. Similarly we
New Fluid: have seen systems where around 20ppm is
Free water, above the saturation point, will
Fluid suppliers do not necessarily guarantee causing maintenance headaches, particularly
circulate as ice particles which will deposit
a low moisture content on barrelled fluid. We where Plate Heat Exchangers are used.
themselves on heat exchanger surfaces, in
have tested new fluids at 60—80ppm:- not
chiller heat exchangers and in expansion tanks.
much help if you are running at –30°C!!
It should be noted that the surface temperature
on heat exchangers will be far lower Poor Housekeeping: What can be done?
than the circulating fluid and that the External filling points unprotected from the
weather. Barrels stood upright and not properly Our units, available for hire or purchase,
refrigerant temperature should be taken into
dried before use. Barrels that are partially full are connected to the system as a side stream,
consideration. Allow at least 10°C lower than
being stored upright wit loose caps. The use of taking a proportion of the flow through a heat
the fluid requirement.
non dedicated filling pumps and hoses. exchanger to a temperature below the boiling
As systems are closed loop, eliminating water is point of the HTfluid and above 100°C.
not easy. Cycling chillers and allowing individual Plant Failure:
reactors jackets to warm to release water still Water heat exchangers, reactor jackets The fluid is passed through a ‘flash chamber’,
leaves the problem of removal or the water will failing:- the nightmare scenario. over a series of micromeshes, cooled and
simply deposit itself elsewhere in the system. returned to the system. Nitrogen is passed
through the ‘flash chamber’ to pick up
the released vapours and passed through
a condenser.
PPM Reduction in water content in a 20,000 litre system of Dowtherm Syltherm 800
The condensate can be collected for
Starting content 2520 ppm Finishing content 36 ppm
2500*
safe disposal or further reconditioning.
System content 20,000 Litres Rig operated 24hrs per day
2000 Inlet to rig ppm
Outlet from rig ppm Recent example Mobile drying unit on its way to a customer.
System Content: 20 000 Litres of This is ATEX Zone 1 compliant.
1500
Syltherm 800
Drying cycle: 42 hours
1000
* Water removed: 68 litres ject in detail without any obligation.
Water content: 2 520 ppm
* dried to 36 ppm.
500 *
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0 * * * * * *
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5 10 15 20 25 30 35 40
Hours
PPM
Recent example
30000
System Content: 2 500 litres Water / Condensate removal to waste
Batch Drying system
28000 Syltherm 800
2500 litres reduced from 27,700 ppm tp 36.83ppm in 9 hours.
26000 Drying cycle: 9 hours
24000 Water removed: 69.16 Litres
22000
Water content: 27 700 ppm
20000
dried to 36.83 ppm.
18000
Batch Drying system
16000
2500 litres reduced from 27,700 ppm tp 36.83ppm in 9 hours.
14000
12000
10000
8000 Heat Transfer Systems Limited
6000 Ridge Hall, Chapel-en-le-Frith, High Peak
4000 Derbyshire SK23 9UD
2000
telephone 01298 815862
0
fax 01298 815863
1 2 3 4 5 6 7 8 9
e-mail office@heattransfersystems.co.uk
HOURS
website www.heattransfersystems.co.uk