steam vent & condensate drain during winter time

[carol2005]

Ice formation due to atmospheric vent of steam from Backos Pumpless Pump

Backos pumpless pumps are used at my plant for conveying steam condensate. As a design principle, atmospheric vent is required for equalizing the pressue between the condensate receiving chamber and the pumping chamber during the pressurizing circles. However, the steam from the ventline which was routed to a sump causes ice slip hazards during the cold months in the winter (environmental temperature as low as -20C). When the vent is rerouted to a underground piping to a sewer, the flash steam causes severe corrosion problem to the piping. Of course another option is to vent flash steam to a height. But I don't have experience with it. Ice formation and blockage of the 2" vent line is a concern. Your recommendation is appreciated.

 

[JJPellin]

This sounds like it would be comparable to the steam vents we use on steam turbines. Leakage past the carbon rings (shaft seals) valve bushings, etc is directed to a vent stack close to the turbine. The stacks are usually 7 or 8 feet tall and perhaps 2" or 3" pipe. They are insulated but not steam traced. At the bottom of the stack, there is a weep hole or a small bore line (1/2" pipe or tubing) routed to the nearest sewer cup to divert condensate from the stack. The small leak off pipe and the bottom of the stack are usually steam traced under the insulation. We use these at ambient temperatures as low as -40 °C with no reported problems. Of course, our turbine vents tend to be venting continously. An intermittent vent such as you describe might be more tricky if it has a chance to cool down between cycles.

 

[Joesteam]

You can attach the vent of the pumping chamber to the vent of the condensate receiving chamber. If there is a concern that this vent pipe will freeze, then tracing is in order.
If you cannot do this, you are able to use compressed air as the motive force in the pump, you will still get some flash out of the vent, but a greatly reduced amount.