Feeding Condensate in to Boiler 2

Condensate Returing from the process is stored in a Vertical Tank kept below Groung Level.

Can we use Air Compressor to push the condensate in to boiler. Since use of pump may form Cavitation.

Please also advise whether use of de-aerator is must.

 

[TD2K]

What do you mean, use an air compressor to push the condensate into the boiler? Are you talking about a pumpless condensate system like Spirac Sarco offers (along with several other companies)? Technically, you can convert the tank to do this, if it is rated for the correct pressure and the inlet/outlet piping are in the correct physical location.

As far as a deareator, always run BFW through a deareator. It's just cheap insurance for your boiler.

 

Since Temperature of Water in Deaerator Storage Tank is nearly with in 5 degress from Saturation Temperature. We need to give NPSH for pump about 7 to 10 metres, to avoid cavitation.

If you have details about pumpless condensate feeding system for boiler. Please help me.

 

[TBP]

Most industrial deaerator/feedpump arrangements don't require anything like 7 - 10 meters of NPSH.

The typical arrangement is for there to be transfer pumps to move condensate from the tank to the deaerator. Any make-up water required is also added at the DA. (Adding make-up water full of dissolved oxygen to a carbon steel condensate tank filled with hot condensate is inviting serious corrosion problems.) Then there are feedpumps taking their suction from the DA, moving water to the boilers.

It's important to select the DA and feedpumps to match the operating conditions in your plant. Everything needs to be piped correctly as well. This is not difficult to accomplish, however there are many plants suffering on-going problems simply because they failed to properly select and install the correct equipment. And the maddening part is, that to do this correctly very often wouldn't have cost much if any more than the mess they're living with.

 

[TD2K]

This is just one link Lramu

http://www.bellgossett.com/Press/whatsnew.htm

Do a search on google for pumpless condensate recovery and there are lots of links. Check out Spirac Sarco's webpage also, they make these units as does Armstrong and other companies.

 

[MJCronin]

LRamu,

I think everyone is missing an important point here...

Since condensate is collected in an underground reservoir( which, by the way, is the worst thing you can do with this type of system) I am willing to bet that the tank is being reused from another purpose.

Everyone is trying to think of a "non-cavitating" way to move the liquid from a bad location.....

Scrap the tank......... purchase a real condensate collection tank, forwarding pumps and a real Deaerator. ( it's not all that much)

If you do not monitor and protect the quality of the feedwater NOW, you will be paying for it in the future in the form of "scaled boiler tubes" (low efficiency) then boiler tube failure and ultimately piping system failure.

Remember, engineers install condensate systems because they want to SAVE money in the long run......... not spend more in 16-24 months by replacing the entire boiler plant.

These elementary principles may have been lost on your non-technical boss.....

MJC

 

[AEF]

MJCronin nailed it right on the head. One other point I'd like to add to his list is safety. A scaled or fouled superheater or drum safety valve is every steam engineers nightmare.

 

[vidanes]

I fully agree with Mcronin. I would advise him to contsct a local guy from Spirax-Sarco. They have knowledgable and experience engineers to put this condensate return system working correctlyand saving for him fuel cost. We do this here in our country. I can help you if you have the details of your steam and condensate system.

 

Mr. Vidanes

Here we have 2 Ton 10.54 bar Pressure Rating Fire Tube Steam Boiler. The Condensate Return will be nearly 60-70%.

 

[quark]

LRamu!

Pushing condensate using compressed air and using deaerator is like taking chances. You can better use steam for that application. How ever one point which is not crossing my mind is why underground storage tank for condensate collection? When you are continuously running boiler, the condensate can directly be collected into the feed water day storage tank by using Spirax mixing system which will take care of deaeration also.

As per PCRA suggestions, your feed water temperature can be 90 deg. C if your day tank is at a height of 5 meters from the pump suction level. The condensate will flow upto the feed water tank if it is not exposed to atmosphere anywhere.

Regards, Truth: Even the hardest of the problems will have atleast one simple solution. Mine may not be one.

 

[vidanes]

Condensate that is discharged by the steam traps fitted at the process equipment should be allowed to flow by gravity to a local condensate receiver. The collected condensate should then be pumped to the condensate return line to the feedtank for re-use as boiler feedwater. Since I am well versed on the spirax-sarco pressure powered condensate pump, I highly recommend this to you. They have a compact packaged unit which incorporates the receiver and other ancillaries and all you have to do is fit it in the appropriate manner. I have installed so many here and the end-users are very satisfied with its performance.You can refer to a local spirax guy in your area and he will be able to come up with the correct installation.