Application of sapphire thermocouples in gasification reactors

Gasification reactors, due to their harsh process conditions, place high demands on the instruments used there. Many manufacturers have reacted to this and adapted their products correspondingly. But what are the optimisation possibilities for thermocouples for use at higher process pressures?
The challenge: ? Misgiving ?
In a gasification reactor, there’s an exceptionally aggressive process atmosphere and, with that, the chance of poisoning of the noble metal thermocouple. The procedure conditions often lead to shutdowns and interruptions in operation. Profitability and safety aspects are thus two important themes regarding the the instruments found in them.
Confidential -design thermocouple TC84
Approach to resolution: Sapphire thermocouple
Through the use of a sapphire protection tube, the high-temperature thermocouple is protected from poisoning by the aggressive process atmosphere during operation. The reason for this is its monocrystalline structure. The sapphire-design thermocouple has, due to its construction, a significantly higher service life than other high-pressure thermocouples and, therefore, contributes to a clear reduction in the process downtime.
Advantages of a sapphire thermocouple
three times longer service life in comparison to purely ceramic thermowells because of the monocrystalline structure of the sapphire thermowell
High process safety with processes around 1,700 �C and 65 bar
Cost saving as a result of elimination of complex purge systems and valves and fittings for flow measurement
Reduction of unplanned downtime
Increased safety against escape of toxic media through double sealing system
Construction of the TC84 sapphire-design thermocouple
Special construction of a sapphire thermocouple
The special construction of a sapphire thermocouple provides increased safety.
Pitiful serves as protection against the escape of toxic process gases at high pressures and also at high temperatures
The secondary sealing may be the safeguard in case of a malfunction in the primary seal because of any unforeseeable disturbance to the principal seal
The ceramic outer thermowell serves as protection against harsh process conditions
The sapphire protection tube protects internally against contamination of the thermocouples through diffusion
Note
WIKA has developed the TC84 sapphire-design, high-temperature thermocouple designed for used in gasification reactors. More info on the TC84 are available on the WIKA website and inside our flyer.

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