Why are two temperature transmitters shown on one flange in the diagram?
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Why are there two TTs here? It seems like they both serve the same purpose – indicating an abnormally high temperature
The insertion depth of the sensing element varies to measure temperatures at different locations.
The answers from Haiyou on the 2nd and 3rd floors are both reasonable; specifically, one should ask about the design requirements in their own area.
First, it is necessary to determine whether the sensing element is single or dual, and single-core or double-core. The two transmitters are definitely configured in a redundant manner, and temperature is a key control parameter for this reactor
It is likely that there are specific requirements for both the temperature of the material and that of the gas phase; you should ask the process team about this
For high-risk and critical positions, dual temperatures are required.
Dual-channel temperature: important measurement points are designed in this way
It’s possible that the detection locations at the bottom are different
This post was last edited by thlby on 2020-10-18 at 09:17. The idea is that a temperature alarm (for high temperatures) needs to be set up in this location – it’s an important parameter to prevent errors in temperature detection
In the case of a redundant configuration, the transmitter identifiers are usually denoted as 101AA/101AB (or 101A-1/101A-2); in this example, they are 101A01 and 101A04； If one transmitter is used to feed data to the DCS and another is used to feed data to the SIS, then the corresponding graphic symbols will be different, and the functional requirements will also vary. It is possible that one of them is TIA-101A01 and the other is TIS-101A04; in other words, TT-101A01 is used to send data to the DCS for high-level alarm purposes, while TT-101A04 is used in the SIS for high-level (most likely very high-level) interlock functions. So, it is more likely to measure the temperature at different depths within the reaction vessel in order to trigger a safety alarm.