Disadvantages of recovering condensate by steam trap pressure
Designing a system to recover condensate merely by connecting the steam trap outlets of equipment to a condensate return header located
on the existing pipe rack might seem like a quick fix to recover condensate.
- Lower Productivity – Condensate evacuation from the process equipment is hampered. This can result in equipment productivity issues due to longer startup times and extended heating times (batch times).
- Rejections / Reprocessing – Due to higher back pressure on the steam trap condensate accumulates in the process equipment and required process parameters such as temperature and temperature gradients cannot be achieved. This can impact product quality leading to rejections or necessitating reprocessing.
- Loss of energy – Steam traps are frequently bypassed in order to fulfill process requirements resulting in steam loss.
- Unsafe – Condensate accumulation in the process equipment can cause water hammer, damaging the process equipment and resulting in steam leaks
When the steam trap is directly connected to a return header, the trap is unnecessarily subjected to backpressure on account of the distance condensate has to travel as well as the elevation and bends it has to flow through. As the back pressure on the trap increases, the differential pressure reduces.
However, as explained above, the discharge capacity of the trap depends on the differential pressure.
The illustration below highlights the variation in the steam traps discharge capacity due to a change in its differential pressure. As can be seen, even a small change in the differential pressure, reduces the condensate handling capacity of the trap substantially.
