Introduction
Refinery Eliminates Shutdowns Caused by Lightning
Thermal reactor within a sulfur recovery unit where lightning-induced

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Client
Emerson
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Services
Industrial automation solution
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Technologies
Automation
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Dates
16/12/2017
Description
RESULTS
• Eliminated lightning-induced shutdowns over a three year period
• Improved signal reliability under heavy EMI conditions
• Increased production availability
APPLICATION
Thermal reactor within a sulfur recovery unit where lightning-induced
transients are prevalent
CUSTOMER
Refinery in North America
CHALLENGE
A North American refinery produces valuable light ends, hydrogen sulfide
(H2S), and ammonia. They had been experiencing multiple trips of their
sulfur recovery unit due to high readings (spikes) from grounded
thermocouples and temperature transmitters . These transmitters were
used as safety interlocks in the thermal reactor. Upon investigation, the
root cause pointed toward EMI/lightning induced transients transmitted
either from the grounded thermocouples or field wiring to the field
mounted temperature transmitters. The net result was nuisance interlock
trips, shutdowns and loss of production.
SOLUTION
The refinery installed two Rosemount 644H Smart Head Mount
Temperature Transmitters and the unit has not suffered any lightning
induced shutdowns in over three years.
The Rosemount 644H incorporates a unique diagnostic algorithm
designed to reduce or eliminate the effects of electrical transients, which
can be induced via high voltage process equipment or lightning. The
software solution that is available in every new 644H is called “Open
Sensor Holdoff.” The Open Sensor Holdoff option, at the normal setting,
enables the Rosemount 644H to be more robust under heavy EMI
conditions. This is accomplished by having the transmitter perform
additional verification of the open sensor status prior to activating the
transmitter alarm. If the additional verification shows that the open sensor
condition is not valid, the transmitter will not go into alarm. This software
diagnostic allows the 644 to maintain a good output through most
electrical storms and transients without impacting operations and safety.
Related
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