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I am working with 1" medium pressure steam mains (45 psig) for a batch process. Time between batches is usually short (to the order of minutes) but depending on the day the delay can be hours, and even longer over weekends or holidays.

We recently installed a full set of orifice (venturi) type steam traps. When we start up, the orifices can't handle the condensate load and the back up condensate is causing water hammer in some sections of the piping.

We are a little tight on budget but will look to installing additional (non-orifice) traps in the problem portions of the piping. In the meantime, we are resorting to manually opening/closing the bypass valves to vent the initial condensate.

Is there a better way to prevent condensate backup at startup on a batch process when using orifice/venturi steam traps?

Mahendra Gunawardena
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jmac
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  • It sounds as if the incorrect size orifice inserts have been installed. Which brand of traps did you install? You are welcome to contact me for assistance. –  Mar 22 '15 at 18:25
  • Have you contacted the company that you bought the traps from? I am sure they can easily solve this problem for you. I am assuming the traps have not been sized correctly as venturi orifice traps are made to handle the increased load at start up. in fact they discharge this condensate 2-3 times faster than they do at running load. I work with the GEM Steam trap. if you contact me I can help you with this problem. Maryam –  Jul 21 '15 at 08:29
  • thermodynamic type steam traps work the best. They minimize steam release during operation. – Jrnbeast lol Nov 20 '16 at 19:01

4 Answers4

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Steam Traps can be classified in to many categories which are Mechanical, Thermodynamic and Thermostatic. Venturi Orifice Steam Traps is also another classification even though in reality it is not a typical steam trap. None of the types cannot be called the best since application and operating conditions decide the best steam trap. For ex: Free Float from TLV are the best when it comes to Energy Efficiency (Steam Loss of 0.03 kg/h as per tests according to ISO 7841 and ASME PTC 39) but cannot be used alone in cu-tracing and applications where accurate temperature control below 100 degree centigrade. Similarly Mechanical traps are not suited for extreme pressure applications (above 150-200 bar) where Thermodynamic traps are the best. Thermodynamic traps is the most versatile and economical model compare to Mechanical steam traps. TD traps can also discharge high loads to its size when compared to TD traps with most manufacturers offering a maximum of 3 tonnes/hour @ 40 - 50 barg differential pressure.

It is difficult to answer your question since the only information you have provided is the pressure and the batch operation. Following are the important parameters required to select/troubleshoot a Steam Trap:

  1. Design Pressure and Temperature
  2. Operating Pressure and Temperature
  3. Condensate Load (kg/h or m3/h)
  4. Application (Tracing / Process / Drip) (since you mentioned its batch operation I am guessing it might be a process equipment like Heat Exchanger or Reheater.
  5. Back Pressure / Differential Pressure

Kindly provide this information which will enable me to give you an answer. To give you a simple answer based on the provided details, if your venture orifice steam trap is not the correct one for the load and operating conditions.

Sarfras Roshan
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Is the steam trap installed on the batch heater/ vessel or in the steam main? Best practice for steam design is to install a drip trap before the process heater in the steam main ( thermodynamic is good for this application as pointed out by others) and a process steam trap for the process steam laos. Process or batch heater should use a steam trap for process loads, often a bucket or float type. Thermodynamic traps are good for a drip leg designed to drain the main steam header. The drip leg is usually installed at the end of the header, at the header low point or right before the control valve if that is the low point.

Ohio ChemE
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You have to go for automatic pumping trap, as a normal float trap does not get enough differential pressure, and hence you have to waste lot of live steam by opening bypass valves.

Mark
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Sameer Dhawan
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  • Welcome to engineering stack exchange! While a useful answer, it could be improved with a diagram to show the different traps, and how they could be benefited. – Mark Jun 05 '18 at 17:14
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For steam installation on steam mains, thermodynamic type steam traps are the best suited. If sized correctly, they will solve the issue of water hammer. At the same time they will waste a minimum amount of steam during operation. You can get more information here- Steam Trap Guide

Mandar Karanjkar
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