Craiova power station

Romanian power station modifies concrete chimney using PennguardTM Block Lining System.

The Romanian national electricity generation company, Termoelectrica, is currently modernizing its fleet of power stations. When the largest power station in the Southwest of the country, Craiova Isalnita, had to make a list of its priorities, the 200 m high reinforced concrete chimney was identified as a high risk for the long term availability of the station. The power station then developed a plan for a complete refurbishment of the chimney.

The chimney was a 200 m high, conical reinforced concrete shell, which was internally protected by a sectional ceramic brick lining. The brick lining was placed on concrete supports, attached directly to the concrete shell. Between the concrete shell and the brick lining, there was a narrow space, filled with a thermal insulation material.


PennguardTM lining installation onto concrete chimney shell after removal of the brick flue

Although the design of the chimney was originally quite conservative, the specific operating conditions of Craiova power station created a very agressive environment. The chimney carries the flue gas from four coal fired units with a combined capacity of 400 MW. The coal, which is found locally, near Craiova, contains sulphur. As the four units go through start-ups, shutdowns and load changes, the chimney is frequently exposed to conditions, where acid condensate is formed.

A 1999 technical survey of the chimney showed, that flue gas could penetrate into the space between the concrete shell and the brick lining and, as a result, the concrete shell and the brick lining supports were under attack from sulphuric acid condensate. Furthermore, thermal cycling had created wide cracks in the concrete windshield. It was concluded, that any further deterioration of the chimney would be an unacceptable risk, especially if the earthquake risk in the area was also considered.

Based on a design by a leading chimney construction company, GIP Grup from Bucharest, the chimney was completely refurbished in 2002. Instead of using ceramic brick once again, the internal concrete surface of 4.750 m² was relined using a lightweight PennguardTM system.