Cottam power station

Pennguard® linings prepare multi-flue chimney for wet stack operation

Cottam Power Station is a 4 x 500 MW coal fired power station in England. Its owner, EDF Energy, decided to fit wet limestone Flue Gas Desulfurization (FGD) to all four units. The existing 200 m / 656 ft high chimney with its concrete shell and four concrete flues, each lined internally with ceramic brick, appeared to be in good condition.

It was concluded, that the chimney could continue to be used after the Flue Gas Desulfurization (FGD) retrofit, provided that the flues could be prepared for Flue Gas Desulfurization (FGD) operating conditions.

It was agreed that Cottam Power Station could run the Flue Gas Desulfurization (FGD) plants without flue gas reheat, allowing the units to be placed closely around the chimney with relatively simple ductwork design.

Therefore, the design challenge of this project was, to convert the flues of the existing chimney for FGD wet stack operation.


Existing 4-flue chimney modified for FGD wet stack service

Environmentally safe operation of the wet stack was made a priority from the start of the design process and the owner contracted Alden Research Laboratory from the United States, to study the options for the outlet ducts and the chimney flues.

Based on the consultant’s recommendations, EDF Energy Cottam decided to remove the brick linings from the four concrete chimney flues and to protect the inner concrete surface of each flue directly, using the Pennguard® Block Lining System.

Page 2 and 3 of the Project Report show how the chimney was prepared for FGD wet stack service.

How the power station will prevent acid rain around its wet stack

A wet stack’s undesirable side effect could be the acidic droplet deposits on the power station and the surrounding area. In order to prevent this phenomenon, EDF commissioned Alden Research Laboratory to design an integrated approach to liquid droplet collection, starting from the mist eliminators of the FGD absorbers, all the way to the tops of the four chimney flues.

As part of their study Alden built a 1/16 plexiglass scale model of the ductwork to predict the exact behaviour of the condensate droplets in the gas stream, as they make their way to the chimney.

The results are published on page 4 of the Project Report.