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Abnormal rise in TMT..

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This topic contains 10 replies, has 5 voices, and was last updated by  Anonymous 10 years, 2 months ago.

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  • #2494

    Freddy Martinez
    Participant

    Hi all,
     In one of our coker heaters we are experiencing sudden rise in skin temperature (40-50 deg C/day) while the other passes & heaters are running normal. We have checked all the instruments for malfunction but no findings. Any suggestion????????//

  • #5455

    Anonymous

    It behavior is the same in two or more heaters, then look for common factors: feed quality is the first everybody thinks about, but there are others like velocity steam or water quality (any possible contamination added, especially chlorides, caustic)… If it is an isolated event, then look for recent changes, especially if an upset happened before the sudden rise…Good luck

  • #5454

    Anonymous

    what about the drop pressure for this pass? are you measure the skin temperature with some pyrometer?

  • #5453

    what about the others variable, flow,inlet pressure, delta P, COT, fuel gas , burner behavior, the other skin temperature because if this real you have near to do an online spalling; must be a coke up the pass if this only happened in this only pass, can be a loss a flow, velocity steam or BFW , pattern burner,etc

  • #5448

    Anonymous

    Dear Espana,
    Others variables like  flow (constant),inlet pressure (raising with delta P), delta P (raising with COT), COT (constant), fuel gas (raising with skin) , burner behavior (ok). We did online spalling for this pass, but not successful;
    This pass some time gives 4 month run length & some time 25 days. We doubted feed quality, but other pass & heaters are normal. Any other reasons???? like Na deposits only in this passs?? is it possible?///

  • #5447

    Anonymous

    Dear Espana,
    Others variables like  flow (constant),inlet pressure (raising with delta P), delta P (raising with skin), COT (constant), fuel gas (raising with skin) , burner behavior (ok). We did online spalling for this pass, but not successful;
    This pass some time gives 4 month run length & some time 25 days. We doubted feed quality, but other pass & heaters are normal. Any other reasons???? like Na deposits only in this passs?? is it possible?///

  • #5446

    Mitchell Moloney
    Participant

    Is the temperature real on that pass?  Loose Thermocouple Connection?

  • #5444

    Claus Graf
    Participant

    I would check the instruments (again) to check if the pass flow is correct. A lower flow in one pass can make it coke up faster than the others. Also check the burner fuel gas flow, you might be heating up the coil more in this pass than the others.You said this pass has given you problems in the past, have you done infrared imaging of the radiation section coils ? Have you compared the termocouple temps to infrared imaging temps in the same tube section ? If your spalling was not succesful you could have a spalling steam/ velocity steam flow problem in that pass, again check your instrumentation.
     
    Hope this helps
     
    CG

  • #5443

    Anonymous

    all thermocouples in the radiation box is increasing for this pass. Temperature rise also not from the start of run, for two or three weeks it will run normally (0.5 to 0.7 deg C/day) then suddenly it will rise like anything (40 degC/day). then we r forced to reduce passflows and COT to improve the runlength

  • #5429

    Claus Graf
    Participant

    How many tubeskin thermocouples does your heater have per pass ?
     
    In what locations ?
     
    Regards
     
    CG

  • #5185

    Gaetano Ambrosino
    Participant

    Temperature stability, operation and performance optimization requires accurate real-time temperatures, and the proper and complete combustion of the variety of fuels involved. One key variable is the atmospheric reduced crude (ARC) temperature.

    The ARC temperature is critical for increased gas oil yield, at the same time reducing the Coker feed. Our role is to enable higher refinery throughput rates through better process temperatures.

    The application of Acoustic Pyrometer System can improve the performance of most crude units in refineries with respect to energy efficiency, reliability, utilization, and safety.
    Significant energy savings can be achieved by reducing the amount of excess combustion air to the crude and vacuum heaters.

    If combustion air is not sufficient, after-burning can take place in the upper parts of the heater, resulting in higher temperatures

    This can damage the heater tubes, tube supports, and firebox structure. In extreme cases, the fuel mixture in the firebox can become explosive.

    please visit http://www.seispain.com
    Gaetano.

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