Payback Analysis

A typical payback scenario illustrates the "total cost' advantage that Repowering has over other alternatives.

Situation

A petro-chemical company utilizes steam from a package boiler on a stand-by basis for process requirements. The boiler is cycled frequently and rapidly to fill the steam requirements. The existing boiler has a large amount of refractory, including tile, brick and mortar. This refractory has been a costly annual maintenance problem for the owner. It also insulates the furnace pressure parts, increasing the flame temperature of the burner, resulting in higher NOx emissions.

The owner/operator of the boiler is under pressure to reduce its maintenance-related costs, increase steam output to 150000 # / hr., and reduce its emissions without repermitting. Options under consideration include 1) a retube with a new burner with FGR (increased fan requirements for FGR necessitated a new fan), 2) a new boiler, and 3) package boiler Repowering.

Solution

The Repowering solution includes an ABCO furnace with no refractory on heat transfer surfaces, 100% membrane  waterwall furnace design, increased furnace volume (raising the drum centers & widening the furnace), and installing a Coen "QLN" burner. The old boiler and burner are replaced except for the steam and mud drums. The existing drums, fan, foundation and auxiliaries are incorporated into the new steam generation system. Emissions from the repowered boiler are guaranteed less than the following :

• NOx : 40 ppm @ 3% O2
• VOC : 15 ppm
• CO : 150 ppm

The new emission level is guaranteed without FGR because of the engineered ABCO furnace modifications. No new emissions permitting is required since the cost of Repowering in this case is less than 50% of a new boiler system.