Double shell recuperators

The double shell recuperator is built up of two concentric cylinders of special steel. Flue gas is led in the center and combustion air is heated in the annulus between the cylinders. The flow direction for the fluegas can be upwards or downwards. Air flow is mostly parrallel but can also be counter flow.

For fluegas directions upwards the double shell works also as a stack. A cone with dampers works as furnace pressure control. Waste gases are leaving either to atmosphere or are led to a filter.
A double shell recuperator work for combustion air preheat up to 600°C.

Tube bundle recuperators

A tube bundle type of recuperator is built like a tube row in the periferee of a vertical cylinder. This cylinder is built of carbon steel internally insulated by refractory lining materials. The refractory ling materils consists of insulation materials and closest to the flue gas, different types of heat and corrosion resistant bricks.

The flow direction for the fluegas can be upwards or downwards. Air flow is mostly parrallel but can also be counter flow.
For fluegas directions upwards the recuperator works also as a stack. A cone with dampers works as furnace pressure control. Waste gases are leaving either to atmosphere or are led to a filter.

A tube bundle recuperator works for combustion air preheat up to 750°C.

Two stage recuperators

A two stage recuperator is mostly built up of a double shell mounted on top of and in serie with a tube bundle. The recuperator works also as a stack. A cone with dampers works as furnace pressure control. Waste gases are leaving either to atmosphere or are led to a filter.

A two stage recuperator works for combustion air preheat up to 825°C.