1. Process Gas Waste Heat Recovery Boilers (Fired & Water Tube)

1. Process Gas Waste Heat Recovery Boilers (Fired & Water Tube)

Water-tube boiler with forced circulation (LaMont type)
The applied heating surface elements are bent coils and arranged in principle in the sequence superheater, evaporator and economizer as required. A so-called protective coil is arranged upstream of the superheater coils in order to reduce the temperature stress for the tube material of the superheater in the zone with the highest gas temperature.

In recent years, a design with internally-located headers has established itself whereas the water-tube boilers are concerned. This is advantageous from the aspect of manufacturing because the vessel can be fabricated independently of the heating surfaces. When the unit goes into operation later, this arrangement allows an uncomplicated and time-saving replacement of a complete heating surface bundle.

Fire-tube boiler with natural circulation

Where the fire-tube boilers are concerned, the evaporator is arranged as a bundle of parallel tubes. For the superheating of the resulting saturated steam, coil-shaped heating surface elements are also arranged above the fire-tube part.

In the fire-tube evaporators are concerned, a sufficient cooling of the upper tube plate is a crucial factor. This is provided with a central tube cooling for the purpose of preventing an accumulation of steam bubbles below the plate. Furthermore, the gas inlets are provided with ferrules in order to reduce the direct heat transfer to the tubesheet.

The material is selected for the water-tube as well as the fire-tube boilers in accordance with the requirements for corrosion protection