Air Preheater Seals

Adaptive Air Preheater Brush Seals

Every ton of coal not burned per MW generated eliminates 2.86 tons of CO2 released.

APH power

APH petro APH pulp
Electric Utility Petroleum Refinery Pulp & Paper Plant

 

The patented Sealeze adaptive brush sealing system provides a more effective, more durable adaptive preheater seal with lower life-cycle costs than conventional APH (air preheater) seals.
Sealeze Fig 1

Conventional air-to-gas sealing systems used on rotary air preheaters have evolved little from the metal strip configurations used on the first Ljungstrom APHs of a century ago. These metal strip seals are typically used for radial, axial and circumferential seals that are exposed to corrosive gasses and relatively high temperatures.

steel strip seal broken Unlike brush seals that can flex to accommodate obstructions, rigid steel strip seals tend to bend and break permanently damaging the seal and potentially damaging the APH and causing rotor stoppage.

 
steel strip vs brushSteel strip seals (on the left) are rigid and rapidly wear to the smallest gap size allowing excessive leakage at the wider gaps. A new brush seal (on the right) shows the amount of strip seal lost. The flexibility of the brush seal allows it to deflect at the smaller gaps sizes and then rebound to ensure sealing at the wider gaps.
Power Brush with Quick Lock LogoSealeze Power adaptive brush seals and holders are constructed of stainless steel that easily withstands the corrosive, high-temperature environment found in today’s APHs. These brushes maintain their effectiveness long after conventional seals fail or have substantially degraded.
Fin vs Brush fin
Fin vs Brush brush

Repeated thermal expansions and contractions in large (often 20-meters in diameter, or more) rotors on APHs that are in continuous motion usually cause large irregular seal gaps. At operating temperatures, outer edges of APHs may droop or turn down by as much as 3 inches or more from the cold condition. Metal strips wear (warp, or break) based on the smallest gap size, thus leaving larger gaps unsealed. While leakage rates with properly designed and installed seals should be 10% or less, worn or damaged metal strip seals can show leakage rates of 15% to 20% or more. And, with metal strip seals leakage rates of up to 30% are not uncommon.

Air Preheater with Power Brush Installed 150dpi

Sealeze adaptive brush seals consist of thousands of filaments that form a high-integrity seal and provide a high degree of abrasion resistance, flex life and bend recovery - - not possible with metal strip seals. Each filament is independent and flexible, allowing deflection to conform to any irregularities and gap variations and still return to its original position. A more effective seal is maintained 2 to 5 times longer than metal strip seals, often over multiple outage cycles.

No place is it more evident of the adaptability of the seal than how it conforms in installations with soot blowers. Click here to see the effect on the adaptive brush seals after 135 days of operation from soot blowers with operating pressures up to 175psi.

Power Brush (XSHT) Fin Exposed for Sealeze Cat

The patented Sealeze adaptive brush sealing system for rotary APHs consists of stainless steel brush and holders (or other appropriate materials) with several options and features. The exclusive Sealeze holder design lets you easily remove the brush when replacement is needed. New brush can be installed without having to re-adjust the clearance for the holders. This saves time and eliminates the possibility of gap misalignment. Circumferential, axial, radial and rotor posts seals are available to seal air-to-gas and gas-to-air leakage paths.