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  • 1.  About energy saving and steam traps technologies

    Posted 06-18-2023 05:19 AM

    Hello!

    Regarding to steam energy saving, What is your experience with steam traps? Which is the most significant improvement in energy efficiency you have experienced by changing your steam traps maintenance strategy?
    Which is your experience with venturi steam traps (relatively new technology)?


    kind regards,



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    Eduardo Rivero
    CMRP, Maintenance Leader
    Bilbao
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  • 2.  RE: About energy saving and steam traps technologies

    Posted 06-22-2023 07:20 PM
    Blowing traps, stuck open: these simply dump steam to condensate. This is really easy to justify based on the cost of energy. ROI is only about 4-6 months, even with low pressure process steam and cheap energy costs. The payback period depends on the trap size, steam pressure, and cost of fuel. The US Department of Energy has some helpful publications. Also, steam companies like Spirax Sarco have helpful papers and online calculators.

    Stuck closed: this situation is a little harder and depends on what kind of process you are working with. Stuck traps keep liquid backed up in the steam system.

    For process steam, the liquid will back up and flood heat exchangers. Even though it is hot to the touch or IR camera, the flooded heat exchanger will no longer be transferring latent heat of vaporization. The process heat transfer will be much lower as a result…like, 1/1000 lower no matter if you increase flow.

    If the stuck trap backs up and floods a control valve, or even slightly increases the back pressure on a control valve that discharges to the same section of condensate piping: the pressure drop assumption will be violated so the valve sizing and loop tuning will be wrong. The control valve will likely open wide, but flow will still be too low to satisfy the control loop demand. What happens next depends on your operators and process engineers. I’ve seen operators simply open the CV bypass valve and take manual control, but leave it that way for years. Why have a DCS if you bypass the control valves? This led to process instability and increased heating and cooling costs, in my experience, due to overheating (by steam), then over cooling by chill water. This sort of process drift is very, very costly, but a bit harder to diagnose and quantify.

    Stuck closed traps also increase carryover and entrainment of liquid, causing erosion of down stream pipe elbows and hopefully not a turbine blade. At the least, emergency pipe repairs will result, along with the danger of steam leaks that injure operators as they clean up the hot condensate.

    Stuck closed traps also increase hammer from flashing in the steam pipe, another way to cause emergency pipe repairs.





    ---------------------------------
    Karl Burnett

    General Electric
    Anderson SC
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    Original Message


  • 3.  RE: About energy saving and steam traps technologies

    Posted 06-23-2023 08:10 AM

    Karl brings up a great point.  I was going to reference you to the US Department of Energy programs - one was referred to as 'Steam Challenge' in the 1990s and was applied at a number of facilities including General Motors facilities in the early 2000s.  Energy savings through steam trap maintenance will have significant payback through a number of 'channels,' in particular condensate return.

    Here are those references:

    There are two software programs available (free - or, at least, paid for by our tax dollars) including the 'Steam System Modeler' and 'MEASUR' which is an overall software tool for analyzing systems and performing 'what-if's'.  It is being kept up as an open source project overseen by Oak Ridge National Labs and replaces/combines the primary software tools and calculators that the program developed in the 1990s and early 2000s.

    You will also find in the calculators that they will provide not just monetary payback but will also calculate the emissions associated with the conditions being evaluated.  There is a strong emphasis on the energy/emissions impact of maintenance, which is something we identified in these programs starting in 1993.



    ------------------------------
    Howard W Penrose, Ph.D., CMRP
    Random Past SMRP Chair (2018), 2019+ Govt Relations Smart Grid, Infrastructure and Cybersecurity Working Group Chair,
    Chair Technical Standards wind, solar, energy storage, American Clean Power (formerly AWEA), and
    President
    MotorDoc LLC
    Lombard, Illinois
    ------------------------------

    Original Message


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