Particle Deflector & Internal Shield (PD)
A heavy-duty internal deflection shield engineered for vertical and inclined ductwork with upward particulate flow, preventing boundary-layer gravity back-tumbling of abrasive solids from entering and packing the expansion joint cavity.
In vertical and inclined ducts conveying upward gas flows, solid particles entrained in boundary-layer flow decelerate and slide backward under gravitational acceleration. In unprotected expansion joints, these abrasive particles accumulate in the annular cavity behind the liner, compacting into solid stone (ash packing) that blocks compression and shears the fabric belt.
The BundleTec Particle Deflector (PD) features an aerodynamic reverse-angled L-profile lip inclined at 30° to 45° into the flow stream. It intercepts sliding wall particles and slingshots them back into the high-velocity core stream, achieving over 99.2% particulate exclusion from the expansion joint cavity.
Thermal Duct Expansion & Sizing Engine
Interactively calculate axial and lateral thermal expansion, temperature gradients, and cold setting offsets.
Overview
The Particle Deflector (PD) is an authoritative internal component engineered to eliminate catastrophic expansion joint failures caused by particulate compaction in vertical duct runs. Designed strictly to FSA-DSJ and RAL-GZ 719 specifications, it prevents hot abrasive clinker, fly ash, and silica sand from packing the carcass cavity, safeguarding plant uptime and equipment reliability.
Applications
- Cement Rotary Kiln Inlet & Preheater Cyclone Ducts
- Coal Mill Separator Ducts & Pulverized Fuel Lines
- Fluidized Bed Boiler Flue Gas Upward Ducts
- Steel Mill Sintering & Dust Collection Mains
- Lime & Gypsum Calcination Furnace Upright Ducts
Technical Advantages
- Blocks particulate penetration into the joint cavity by over 99.2%
- Eliminates ash packing lockup and premature fabric belt blowout
- Hardox 400/500 wear plates ensure 5+ years of continuous abrasive service
- Modular bolt-on segments enable rapid internal maintenance without duct disassembly
- Full compliance with FSA-DSJ and RAL-GZ 719 international engineering norms
PD Technical Parameters & Operational Limits
| Applicable Duct Geometries | Vertical and Angled (>45°) Upward Flow Ductwork |
| Design Gas Velocity | 10 m/s to 45 m/s |
| Plate Thickness | 4 mm to 12 mm (Sized to duct cross-section and wear load) |
| Thermal Expansion Margin | ΔL_thermal + 20 mm floating slip allowance |
| Standard Compliance | FSA-DSJ-401/402 · RAL-GZ 719 Categories I-V |
| Connection Topology | Continuous Full-Penetration Weld or Replaceable Bolted Segments |
Particle Deflector & Internal Shield (PD) — Detailed Architectural Design
1. Aerodynamic Function & Fluid Dynamics Analysis
In upward vertical flows, fluid velocity at duct walls approaches zero due to boundary-layer friction. Heavy abrasive particles drop downward under gravity and tumble into the annular space between conventional liners and the expansion joint frame. The BundleTec PD reverse-angled L-lip catches these descending solids and slingshots them into the high-velocity core stream, protecting the flexible carcass cavity.
2. Thermo-Mechanical Stress & Differential Expansion
Exposed to raw flue gas and particle impingement, substantial temperature differentials (up to 200°C) develop between the duct wall and deflector shield. FSA-DSJ compliant slotted mounting holes and slip-joints prevent thermal stress accumulation and low-cycle fatigue cracks, while FEA resonance tuning eliminates flow-induced vibration.
3. Metallurgy, Abrasion Resistance & Welding Norms
High-hardness solids (Mohs 6-7) scour structural carbon steel rapidly. BundleTec fabricates PD shields from Hardox 400/500 wear plates for temperatures under 450°C, and austenitic heat-resistant AISI 310S or Inconel 625 for temperatures up to 1000°C. All welds are executed to EN ISO 15614-1 standards with radiused flow edges.
4. Field Failure Modes, Assembly & Preventative Maintenance
Cement kiln audits show unprotected cavities collect over 400 kg of hot clinker within 3 months, bending flanges during subsequent thermal expansion cycles. Installing the PD deflector eliminates this failure mode permanently. Ultrasonic thickness inspections during annual outages identify worn bolt-on segments for quick turnaround.
Calculate duct thermal growth and configure the right component →
Input duct cross-section and process temperatures to immediately determine axial and lateral displacement.
Compliant International Quality & Manufacturing Standards
All internal expansion joint components are engineered and fabricated to FSA and RAL-GZ 719 guidelines.
Gütegemeinschaft Weichstoff-Kompensatoren temperature categories 1-5, helium tightness and tensile strength standards.
Fluid Sealing Association FSA-DSJ-401/402 carcass internal hardware, flow liners, and clamping torque allowances.
Directives for static dissipation, equipotential bonding bridges, and explosion protection in Zone 1/21 environments.
Frequently Asked Questions
What is the difference between a Particle Deflector (PD) and a standard Flow Liner? +
A standard flow liner only directs bulk axial flow; in vertical ducts, tumbling gravity particles slip behind the liner and jam the joint cavity. The Particle Deflector (PD) features a reverse-angled L-lip that intercepts descending particles and slingshots them back into the core stream.
In which duct geometries is the PD deflector essential? +
Any vertical or inclined ductwork carrying upward gas flows with high solid particulate loading—such as cement kiln preheaters, coal pulverizer ducts, and fluidized bed boiler risers.
Which alloy grades are utilized for PD shields? +
Hardox 400/500 abrasion-resistant plates for abrasive flows up to 450°C; AISI 310S, Inconel 625, or 253 MA superalloys for temperatures between 500°C and 1000°C.
Can wear segments be replaced without unmounting the expansion joint? +
Yes, BundleTec PD systems feature modular bolt-on wear segments accessible from within the duct manhole, enabling fast replacement without disturbing the expansion joint carcass or duct structural framing.