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Reaction
gas
Infrared Energy
Lens
Assembly
Claus
Thermal
Reactor
Thermal
Insulation System
Rain
Shield
Isolation
Valve
Purge
Supply
Steam
Supply
Steam
Outlet
Thermal
Insulation
System
Delta Controls Model HIR is an infrared temperature pyrometer specifically designed to measure the refractory
temperature of Claus Process thermal reactors.
1. THEORY OF OPERATION
Model HIR uses infrared pyrometry to measure temperature. All materials radiate energy as a function of their absolute
temperatures. Model HIR “looks” into the reactor and senses the amount and spectrum (wavelengths) of the infrared
energy being emitted by the hot face of the refractory. The sensed energy is converted into a signal, which can be used to
accurately display the refractory operating temperature.
1.1 Considerations when using Infrared Pyrometry in Claus Thermal Reactors
To effectively measure temperature, the instrument needs a clear, unobstructed view into the vessel. The infrared energy
must pass through the reacting gases without being absorbed by them. The instrument must “look” through those same
gases without seeing them or sensing their high temperatures. This is accomplished by using optical bandpass filters. The
selected sensing spectrums avoid errors due to absorption, reflection, etc.
A potential problem using infrared pyrometry in a Claus thermal reactor is that sulfur or other solids can accumulate on the
lens or in the nozzle which blocks the infrared radiation, and requires expensive maintenance to clean the lens and optical
path. Model HIR is designed to be nearly maintenance free. When properly installed and operated, it maintains the lens,
sighting window, and nozzle at a sufficiently high temperature to avoid sulfur buildup and reduces frequency of periodic
cleaning.
Figure 1
