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| Spirax Marshall>> Complete Steam Solutions>> Steam Distribution>> Best Engineering Practices |
Steam should be dry. Remove moisture!
Steam generated in boilers is always wet. Approximately 5%(for good boilers, could be as bad as 30% of NIBR coil type boilers operating inefficiently) of its mass will be water and unless it is removed it will be carried into the steam distribution system where it is definitely not desired. Added to this 5% water will be the condensate of the steam formed due to radiation losses through the pipe surfaces. The end result is a decreased overall plant efficiency with reduced performance and production rate from the process equipment, particularly in the application of steam operated vacuum ejectors used for vacuum evaporating and drying of the product. Moisture in the steam systems also could lead to water-hammer, which may damage the in line equipment/accessories.
It is accepted as a good practice to fit a steam/water Separator on the main steam offtake from the boiler in order to collect and return the 5% water carried over from the boiler by the steam.Make certain that the pipe gradients are correct (a fall of 1:200 is suitable) so that the condensate will gravitate to the drain points (steam traps) that should be fitted approximately every 30 meters and at the base of each rising steam main.
The drain point should be designed like this
The job of the steam trap is to discharge the condensate without letting out any steam, which would be a waste of energy that cannot be tolerated under any circumstances.
Because the load is low and the trap has to withstand a high pressure, in the steam distribution system the best choice for a steam trap is a thermodynamic steam trap. The Thermodynamic Steam Trap can also handle superheated steam and is not damaged by water-hammer or vibration. If the steam distribution pipelines are installed outside, another advantage of this kind of trap is that being frozen does not damage it.
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