Eclipse Engineering


Eclipse Engineering

Duct Design Methodology

To follow is a typical chronologically-ordered scope of work Eclipse provides to its clients for the flow and structural design of flue gas ducts. Some of the analyses we perform have an accompanying report for the client and are appropriately noted.

  • Determine temperature distribution through duct leg for slide plate material selection
    Deliverable - Report showing maximum expected baseplate temperature

  • Determine corner clip locations (to prevent ash fallout)
  • Determine optimum vane design using CFD
    Deliverable - Report showing system pressure drop, detail of velocity profile at regions of possible particulate fallout, and velocity data at fan and/or equipment inlets with comparison to AMCA allowable deviation, if pertinent.

  • Determine duct plate effective modulus of elasticity which accounts for buckling failure of the duct skin
  • Evaluate vane design for flow-induced vibration loads, and stiffen as required
  • Perform duct skin thermal analysis to minimize use of expensive special alloy near regions of potential gas condensation
  • Create finite element model of duct, bracing, stiffeners, and support steel (where support steel stiffness will affect the duct design or the imparted loads upon the support steel)
  • Specify trial section properties based upon previous experience
  • Derive and apply loads (dead, live, ash, pressure, snow, wind, seismic, friction)
  • Apply displacement boundary conditions which allow for duct thermal expansion
  • Optimize section properties to minimize cost while allowing for sufficient design safety margin
  • Evaluate duct structure for emergency-temperature load case (also known as excursion)
  • Evaluate internal bracing for flow-induced vibration loads
  • Perform connection design
    Deliverable - Report detailing load derivation, boundary conditions, AISC and ASME Code comparisons, and other analysis assumptions
    Deliverable - Duct loads imparted to support steel or foundation
    Deliverable - Duct design drawings showing proper dimensions and arrangement of stiffeners, braces, and turning vanes
    Deliverable - Sheets of standard details fully describe the design