A Case for Condition Monitoring of Steam Traps
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A case for Steam Traps condition monitoring Kannan Palanisamy 02 Oct ‘12
description
Condition monitoring techniques for steam trap.
Transcript of A Case for Condition Monitoring of Steam Traps
A case for Steam Traps condition monitoring
Kannan Palanisamy02 Oct ‘12
Decription of AssetOur company has around 1000 steam traps.Steam traps exist to discharge air and steam-condensate
while not permitting the escape of live steamTheir goal is to ‘purify’ the steam of excess air and water
(condensate) to :Improve efficiency (Excess water or air in the system prevents it
from reaching operating temperature quickly during start-up)Protect system (Inadequate steam trapping can lead to
waterhammer, corrosion, leakage, and high maintenance costs)Provide maximum heat transfer (‘dry’ steam has best heat
transfer properties in equipment like a heat exchanger
Steam Trap Types
Mechanical
Use difference in density between
steam and condensate to
operate float to get rid of steam condensate
Thermodynamic
Steam (flash) –flow operates valve to get
rid of steam condensate
Thermostatic
Sense temperature change of condensate
to get rid of steam condensate
Different types of Steam trap in the industry
Types of steam traps used in my company
Our company has thermodynamic steam traps and mechanical steam traps.
Linkage
Ball
Seat
Thermodynamic steam trap
Mechanical float typesteam trap
Recent issues faced due to steam trapsRecently we had several steam jacketed lines
failed due to corrosion issues as the jacket did not sufficiently heat the sulphur di-oxide rich gas on the inside pipe causing acid condensation on the inside pipe and the several jacketed spools buckled due to corrosion.
The root cause of the spool failures were attributed to steam traps that did not discharge the steam condensate properly leading to corrosion and failure of the inner pipe due to acid condensation at low temperature.
Photographs of the corroded jacketed spools
Failure modes of steam trapsBlocked Traps - Upstream is completely
build-up with steam condensate.Low Temperature Traps – Unable to
discharge the steam condensate. Trap likely to get ‘blocked in the future’.
Leaking Traps – These traps cause monetary loss by leaking steam.
Blowing Traps – Blowing Traps are completely damaged and is letting steam blow out.
Blocked and Low Temperature traps cause process issues due to insufficient heating whereas the leaking and blowing traps are monetary loss to the company
Condition monitoring of steam trapsConventional methods
Operator observationsCondition monitoring techniques
Temperature monitoringUltrasonic monitoringContinuous monitoring systems (conductivity
etc)
Operator observations
A LEAK!!!
• Identifies leaking traps and blowing traps in open system.
• Subjective
Temperature measurement (Infra red monitoring)
RETURN SYSTEM
Temperature based onreturn line steam pressure
Only indicates a blockage
• Indicates blowing traps and low temperature traps
• But cannot quantify
Ultrasonic monitoring
RETURN SYSTEM
ADJUST• Grades leaking
traps
Typical average condition of traps without monitoring program
Typical failure mode distribution of steam traps
BLOCKED5.6%WORKING
CORRECTLY62.6%
LEAKING18.7%
INCORRECT OPERATION
13.1%
Case for monitoring of steam trapsCost of Monitoring 1000 traps Annually by
operator observations, temperature and ultrasonic monitoringOperator cost – 1000 x 5 minutes x $200/60 =
$16666Temperature & Ultrasonic monitoring – 1000 x
10 minutes x $200/60 = $33333Our company already has the IR temperature
instrument and the ultrasonic instrument – So the cost of the instrument is not considered.
Total cost - $50000
Benefit/CostThis steam trap monitoring program is
expected to save at least one incident like the sulphur jacketed line failure per year and also prevent the monetary loss of leaking/blowing steam traps.
Cost of one incident like the sulphur jacketed line failure - $ 100000
Cost of leaking/blowing on about 20% steam traps (200 leaking traps per annum ) - $ 50000 for a steam price of $ 8 per tonne.
Benefit – cost ratio = ($150000/$50000) = 3
Benefit/Cost table for 1000 steam trapsDegradation mode
Recommended Monitoring method
Frequency
Cost of Condition Monitoring
Impact of Failure
Cost of Break down
Beneft/Cost Ratio
Blocked traps
Trap Man Monitoring
1y $50000 $50000
$100000 3
Low Temp. traps
Trap Man Monitoring
1y $50000 $50000
$100000 3
Blowing Traps
Visual Inspection & Trap Man Monitoring
1y $50000 $50000
$100000 3
Leaking Traps
Visual Inspection & Trap Man Monitoring
1y $50000 $50000
$100000 3
