Sizing steam condesate return pump

[SAK9]

I have a heat exchanger which condenses steam at the rate of 300 kg/hr.What should be the flow rate for the condesate pump?Should it be also 300 kg/hr or higher with some margin.Some one advised me it should be twice ie 600 kg/hr due to higher condesation rate during startup

 

[TBP]

I do better in Imperial, so you'll have 660 #/hr of condensate to handle. 660 divided by 500 = 1.32 USGPM. I'd talk to Spirax Sarco, Armstong, or other similar outfits about what they have in their product line that will work best in this application. (Who's control valve and trap are you using?) You'll likely have a tank that takes a few minutes to fill (that should take care of surges like start-up loads) and maybe a pump rated for 2 or 3 GPM. It may be convenient to dump this condensate to an existing larger condensate receiver, in which case, you won't need a tank & pump set anyway.

 

[SAK9]

Many thanks TBP for your response.I would be using a Spirax Sarco unit.What in your opinion is the best option a recovery system with duplux electric pumps or a single steam actuated(Ogden)pump?I believe the latter is much cheaper but unsure about any maintenance issues

 

[quark]

It is better to have a pumping trap for heat exchanger application to avoid stall during low load operation. I have been using Ogden pumps for past 8 years and there are no serious problems.

 

[TBP]

Pumping traps are a good choice in problem applications, but they are pricey. If the HX is installed high enough over the receiver, the trap discharge can be essentially downward, draining the HX by gravity. If this situation exists, then it's not necessary to have a pumping trap.

Electric motor driven condensate pumps are often a good choice, but the pressure powered pumps have their applications as well. The selection depends upon a lot of local factors. The Spirax rep should be able to identify the suitable options for this particular installation.

 

[abcmex]

TBP,
I agree with Quark; an Ogden pump (if there are several equipments to be connected) or a pumping trap (if there is only one) may be used. A pumping trap is pricey but has a lot of advantages and compared to the total price (trap + ogden pump) should be cheaper.

Air heaters for HVAC are a typical case for Ogden pumps or pumping traps due to the stalling problems.

Kind regards

 

[TBP]

I'm not saying they don't have their applications, just that pumping traps are used in a lot of places where they aren't necessary. The vast majority of HVAC heaters can be piped such that stall won't be an issue, even without a pumping trap. Air heating applications were successfully installed for 100 years before pumping traps hit the market. In those rare applications where "you can't get there from here" on a new installation, or as the most economical fix for an installation that was wrong from the beginning - those are the times for a pumping trap. Most often, however, if the installation is designed & installed by people who know steam, and understand stall, there are no problems. Spirax Sarco's "Hook-Ups" has a section on this, and the piping schematic to go with it. Pumping traps cost far more upfront than conventional traps, and the maintenance costs are proportionatly high.