We’re dealing with a recurring issue on our Alstom-built HRSG where the ammonia injection lances keep falling out of place. This is causing ammonia slip and uneven distribution, leading to compliance concerns. It seems that the supports for the lances aren’t sufficient, especially during thermal cycling.
Has anyone else experienced similar problems with lance supports on Alstom units? What fixes or retrofits have worked for you?
We had the same issue on our Alstom HRSG, and it turned out that the original support brackets weren’t designed to handle the thermal expansion during startup and shutdown. We reinforced the upside supports to prevent flexing of the walls, which can happen during thermal cycling. Additionally, we extended the support brackets to account for slippage when the system heats and cools. This approach provided more stability and resolved the problem.
Check your weld points on the lance supports. We found that poor-quality welds were failing during thermal cycling, causing the lances to drop. Upgrading to high-temperature-resistant welds made a big difference for us.
Are you sure the support issue is the root cause? In some cases, vibration from duct burners can loosen the lances. If you have duct burners, check their alignment and make sure they’re not causing excessive vibration.