Lippendorf lignite-fired power station

The cooling towers of the Lippendorf lignite-fired power plant near Leipzig were to be refurbished as a result of damage caused by acidic condensate on the liner surfaces. The operator, Lausitz Energie AG (LEAG), put its faith in MC-Bauchemie's 50 years-plus of expertise in the power plant sector and, more specifically, in the high-performance coating MC-DUR 2496 CTP, a product system especially developed for cooling tower applications.
Lippendorf lignite-fired steam-turbine power plant in the municipality of Neukieritzsch is located about 15 km south of Leipzig and serves a catchment area including the Saxony metropolis. When the power station was commissioned in 1999, it was considered the most modern lignite-fired facility in the world. Its two units each offer a gross generating capacity of 933.6 megawatts. The exhaust gases produced during coal combustion are cleaned by electrostatic precipitators and flue gas desulphurisation systems.
Cooling tower inner shells corroded by acidic condensate

Each unit has a natural-draught cooling tower made of concrete with a height of almost 175 metres. The process water is cooled in the two towers, which are also used to release the cleaned exhaust gases into the atmosphere. However, these cleaned exhaust gases still produce an acidic condensate that precipitates on the inside of the cooling tower shells and would attack the concrete if allowed to penetrate the protective linings.

 

New studies have shown that the action of acidic condensate in combination with UV irradiation produces so-called photocatalytic effects which cause a loss of layer thickness in epoxy resin coatings in a process known as “chalking”. Over time, this can mean dangerous depletion of the layer protecting the concrete substrate. Regular monitoring at Lippendorf provides a constant flow of detailed information on the remaining thickness of the surface protection system.

 

As Unit R was scheduled to be shut down for lengthy maintenance purposes in 2020, Lausitz Energie AG decided to use the time to repair the inner shells of the cooling towers, and specifically to refurbish the existing surface protection system in some areas so as to prevent more severe damage occurring once operations restarted.

 

Lasting protection with MC-DUR 2496 CTP

The contractor selected to perform the rehab work was the Moritzburg branch of Massenberg GmbH, which joined with the operator and the power plant specialists of MC-Bauchemie in planning the refurbishment campaign. The product system chosen was MC-DUR 2496 CTP, a special coating developed for use in cooling towers. MC-DUR 2496 CTP is based on MC’s advanced KineticBoost Technology®. This produces fast, reliable results in the form of an almost weather-immune complex. The two-component, UV-stable and fast-curing speciality sealant also impresses with good resistance to dilute acids, lyes and salt solutions. It offers increased application time combined with accelerated curing (once applied) virtually free of any moisture or temperature influence. And there is a further benefit: It can be applied over old coatings without any detrimental impact on its efficacy. The excellent UV stability of this special sealant reliably ensures the avoidance of "chalking". And needless to say, MC-DUR 2496 CTP comes with comprehensive proof of suitability for coating natural-draught cooling towers with flue gas injection.

 

Prior to the repair of the inner shells, the existing coating was prepared by sweep-blasting. This particularly gentle sandblasting technique both removes loose material and roughens substrate surfaces for better adhesion of the new coating. Subsequently, the new top coat was roller-applied in two passes with an inter-pass colour change.

 

As well as affording exceptional protection – as impressively demonstrated by the results achieved in the cooling towers of the Lippendorf power plant – MC’s super-resilient high-performance coating also offers a key environmental benefit in that, in contrast to conventional systems, it is virtually solvent-free. MC-DUR 2496 CTP with KineticBoost-Technology® is thus ideal as a sustainable solution for the repair of cooling towers in Europe and beyond.