Application of sapphire thermocouples in gasification reactors

Quiet , because of their harsh process conditions, place high demands on the instruments used there. Many manufacturers have reacted to the and adapted their products correspondingly. But which are the optimisation possibilities for thermocouples for use at higher process pressures?
The task: ?Gasification reactors?
In a gasification reactor, there’s an exceptionally aggressive process atmosphere and, with that, the risk of poisoning of the noble metal thermocouple. The process conditions often lead to shutdowns and interruptions functioning. Profitability and safety aspects are thus two important themes regarding the the instruments found in them.
WIKA sapphire-design thermocouple TC84
Method of resolution: Sapphire thermocouple
By using a sapphire protection tube, the high-temperature thermocouple is protected from poisoning by the aggressive process atmosphere during operation. The reason for that 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 decrease in the process downtime.
Advantages of a sapphire thermocouple
3 times longer service life compared to purely ceramic thermowells as a result of monocrystalline structure of the sapphire thermowell
High process safety with processes up to 1,700 �C and 65 bar
Cost saving because of the 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.
The principal sealing serves as protection against the escape of toxic process gases at high pressures and in addition at high temperatures
The secondary sealing is the safeguard in the event of a malfunction in the principal seal due to 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 specifically for use in gasification reactors. More info on the TC84 can be found on the WIKA website and inside our flyer.

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