×
INTELLIGENT WORK FORUMS
FOR ENGINEERING PROFESSIONALS

Log In

Come Join Us!

Are you an
Engineering professional?
Join Eng-Tips Forums!
  • Talk With Other Members
  • Be Notified Of Responses
    To Your Posts
  • Keyword Search
  • One-Click Access To Your
    Favorite Forums
  • Automated Signatures
    On Your Posts
  • Best Of All, It's Free!
  • Students Click Here

*Eng-Tips's functionality depends on members receiving e-mail. By joining you are opting in to receive e-mail.

Posting Guidelines

Promoting, selling, recruiting, coursework and thesis posting is forbidden.

Students Click Here

Jobs

steam coil air heater

steam coil air heater

steam coil air heater

(OP)
we are going to build a power plant in warm West Africa.  I plan to eliminate the use of SCAH.  Is it acceptable?

RE: steam coil air heater

Currently working on coal fired plant in south east asia with 0.7% sulphur.

Design ambient 28C, airheater outlet gas temperature 126C giving average cold end temperature of 77C. Minimum recomended by airheater supplier 66C.

There is no SCAPH on this plant.

Regards,

athomas236

RE: steam coil air heater

If it is for the concern of air heater acid corrosion, You do need something to heat up the air before it goes to the air heater. As an alternative of SCAH, if you don't want to use it, you can consider 'hot air recirculation'. A certain percentage of air already heated up by the air heater is re-directed back to the FD fan inlet and goes through the air heater again. This further raises the inlet air temperature and protects the air heater from acid corrosion in cold winters. Even though your boiler will be installed in warm Africa, the system design might already want to take this advantage and use much lower gas outlet temperature to get higher boiler efficiency thus leaves you less room for inlet air temperature fluctuations at the air heater so the protection might still be needed. If the system is conservatively designed with high flue gas outlet temperature good for any weather condition then you should be okay without air-preheating.

I understand that SCAH adds complexities to the thermal system and is notorious for pluggings and water-hammer damages from condensate formations. Nevertheless, SCAH is still recommended mainly because it gives the systems higher efficiencies so has long-term benefits. I was reading about an improved design which avoids water-hammer problems. You might want to find out the details plus who supplies it.

Boilerone

RE: steam coil air heater

I'd have to know a lot more about what type of boiler that you are going to construct before offering an opinion (tip).

What is downstream of the SCAH that it would have otherwise protected would it be there?

I come from the deep south of the USA and have seen lots of SCAH's rotting down from disuse.  The small part of the year when they might have been beneficial, they were inoperative from lack of maintenance.  Many just got taken out (or cut out.)

Most of the APH's downstream of the SCAH's were Ljungstroms and the buckets seem to have a decent life otherwise.

rmw

RE: steam coil air heater

The answer may be in the thread where you ask about APH type selection.

rmw

Red Flag This Post

Please let us know here why this post is inappropriate. Reasons such as off-topic, duplicates, flames, illegal, vulgar, or students posting their homework.

Red Flag Submitted

Thank you for helping keep Eng-Tips Forums free from inappropriate posts.
The Eng-Tips staff will check this out and take appropriate action.

Reply To This Thread

Posting in the Eng-Tips forums is a member-only feature.

Click Here to join Eng-Tips and talk with other members!


Resources