STEAM SURFACE CONDENSER POOR VACUUM

[rajankanwar]

We are operating a surface condenser of 45 MT/Hr condensing duty attached with a steam turbine. The condensing operating vacuum remained quite low i.e 0.60 ata against design of 0.14 ata. The cooling water flow through the condenser appears to be normal. The condenser shell has expansion bellow on one end. On recent inspection, we found some gap in the air-cooling section baffle plate (Shrouding the air cooling bundle) near expansion bellow. It is suspected that air/inert ingress through this gap is responsible for poor vacuum. The gap is across the expansion bellow,
Kindly suggest how to seal the gap as the inert plus steam directly bypasses the surface condenser tube bundle thereby creating a additional load on two stage ejector system.

Er. Rajan Kanwar

 

[rajankanwar]

We are operating a surface condenser of 45 MT/Hr condensing duty attached with a steam turbine. The condensing operating vacuum remained quite low i.e 0.60 ata against design of 0.14 ata. The cooling water flow through the condenser appears to be normal. The condenser shell has expansion bellow on one end. On recent inspection, we found some gap in the air-cooling section baffle plate (Shrouding the air cooling bundle) near expansion bellow. It is suspected that air/inert ingress through this gap is responsible for poor vacuum. The gap is across the expansion bellow,
Kindly suggest how to seal the gap as the inert plus steam directly bypasses the surface condenser tube bundle thereby creating a additional load on two stage ejector system.

Er. Rajan Kanwar

 

[balu1]

Sir Rajankanwar I suppose you are asking too much. We dumb mechanical engineers usually require drawings, mat specs, sketch of the defect and who knows what else just to start thinking about the repair.

This is particularly tough case when the plant is operating. It may not even be feasible to do anything without stopping the turbine. Obviously some welding or brazing is required but that is something you have already figured out.

Again the usual answer: consult the manufacturer or some specialized company.

 

[poetix99]

There is a lot of duct tape here in the US - purchased in anticipation of hermetically sealing our homes against bio-assault, but, luckily, unused (to date).

Cover the "gap" with duct tape. Then, at the next outage, determine whether there is undue strain on the bellow. If "yes", relieve it. If "no", consult the vendor of the bellow for possible remedies.

 

[rajankanwar]

The surface condenser has an air-cooling section inside. A portion of tube bundle is kept separately for inert/air cooling. This portion is shrouded by a welded plate. The steam plus inert/air enter the condenser from top and steam condenses as mixture travels down wards. The air rich mixture then enters the air- cooling section of the condenser (From bottom gap in the Shroud on air cooling tube bundle). We have observed a gap in the air- cooling section top and suspects that direct bypassing of seam instead of air is overloading the ejector system and subsequently low vacuum. The gap is across the expansion bellow provided on shell. How to plug the gap without inducing much stress on the expansion bellow.

The use of bio duct tape may be an alternative but its specifications and ability to withstand 0.16 ata pressure may be explained little further
THANKS
RAJAN

 

[rajankanwar]

i am waiting for reply

rajan