Case Study · Glass Manufacturing
Low-NOx Burner for a Glass Annealing Lehr
A 40 m annealing lehr needed gentle, even stress-relief heat after the tin bath. Weishaupt low-NOx burners with modulating control held the cooling curve in band without over-firing the glass.
The challenge
The lehr must remove thermal stress slowly; old high-velocity burners over-fired and warped thin glass.
Environmental limits tightened on NOx from the lehr exhaust.
Temperature had to track the glass thickness change across product grades.
Downtime for burner change had to fit a tight weekend window.
What we supplied & did
Selected Weishaupt WML20 low-NOx burners for soft, distributed heat in the stress-relief zone.
Fitted a Dungs safety valve train with leak test and dual cutoff.
Added Honeywell C7027 flame detectors and modulating control tied to the lehr belt speed.
Commissioned the burner/recirculation balance to keep the cooling curve gradual.
Measured results
What changed on the line
The annealing curve stays within band across grades, cutting warp and breakage.
Low-NOx burners cleared the tightened emission limit without add-on treatment.
Modulating control follows belt speed, so product changeovers need no manual re-trim.
Installation finished inside the planned weekend window.
Equipment used in this project
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