Abstract: The catalyst activity in acetylene hydrogenation reactors of ethylene plants is highly sensitive to temperature. Unstable temperature control may readily cause acetylene breakthrough or reactor runaway. Therefore, the accurate and stable control of reactor temperature is particularly important. The inlet temperature of the acetylene hydrogenation reactor is controlled by the control function block TIC30295, and the temperature element TE30295 is a K-type thermocouple equipped with E+H temperature transmitter. Temperature fluctuations in the reactor occurred multiple times during summer rainstorms and periods of significant temperature shifts, leading to corresponding emergence of acetylene content variations at the reactor outlet. A comprehensive multi-perspective analysis has been conducted on these fluctuation phenomena. Through simulated temperature measurement experiments, the root cause of aberrant fluctuations in the temperature control loop of the acetylene hydrogenation reactor due to ambient temperature variations was identified, enabling sustained stable operation of the reactor over extended periods. Concurrently, dynamic temperature measurement experiments revealed the inherent limitations of thermocouple cold-junction compensation in industrial applications. This led to the proposal of replacing thermocouples with Pt100 resistance temperature detectors (RTDs) as the solution.

Key words: acetylene hydrogenation reactorlthermocouplelcold-junction compensationltemperature transmitter