Regenerative Air Pregeaters in ACFB boilers
Regenerative Air Pregeaters in ACFB boilers
(OP)
Hello,
We are selecting a contractor for a new 300 MW coal fired utility in South America, the boiler will use ACFB (Atmospheric Circulating Fluidized Bed) technology. In the same place we are already erecting a 150 MWe unit with ACFB boiler and one regenerative Ljungstrom air preheater.
For the new unit we requested two flue gas trains (Air preheater, bag filter, ID fan) each one 60% capacity (we have used this configuration in some 150 MWe PC boilers we opperate), but one of the possible bidder argumented that two Ljungstrom air preheaters shall not be used in ACFB boilers so they will supply only one.
Is there any limitation about the number of air preheater for a ACFB boilers or it may be decied freely by customer? I've seen many units in many sizes with two air preheaters but all were PC technology.
By the way, we allowed bidders to propose either tubular or regenerative air preheater.
Thanks all for your help.
We are selecting a contractor for a new 300 MW coal fired utility in South America, the boiler will use ACFB (Atmospheric Circulating Fluidized Bed) technology. In the same place we are already erecting a 150 MWe unit with ACFB boiler and one regenerative Ljungstrom air preheater.
For the new unit we requested two flue gas trains (Air preheater, bag filter, ID fan) each one 60% capacity (we have used this configuration in some 150 MWe PC boilers we opperate), but one of the possible bidder argumented that two Ljungstrom air preheaters shall not be used in ACFB boilers so they will supply only one.
Is there any limitation about the number of air preheater for a ACFB boilers or it may be decied freely by customer? I've seen many units in many sizes with two air preheaters but all were PC technology.
By the way, we allowed bidders to propose either tubular or regenerative air preheater.
Thanks all for your help.
Javier Guevara E.
Projects, Mechanical Engineer
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RE: Regenerative Air Pregeaters in ACFB boilers
Valuable advice from a professor many years ago: First, design for graceful failure. Everything we build will eventually fail, so we must strive to avoid injuries or secondary damage when that failure occurs. Only then can practicality and economics be properly considered.
RE: Regenerative Air Pregeaters in ACFB boilers
Having said that , the use of a Ljungstrom style APH on a CFB can lead to other issues, mainly excess air leakage and higher than guaranteed SA fan power consumption. The trend in most CFB's is to use multiple tubular or heat pipe style APH's in series with an intermediate water cooled economizer- this limits the air leakage to almost Nil.
RE: Regenerative Air Pregeaters in ACFB boilers
rmw