Moorburg, Circular Hybrid Cooling Tower

The cooling tower of a large power plant is generally its most visible part. A natural draft tower for a 1600 MW plant is quite tall and its plume is visible from many kilometers around. An induced draft cooling tower for a similar power plant consists of many cells arranged in blocks. Such a cooling tower requires a very large ground surface and is energy-consuming. Plume visibility and generated noise have adverse environmental effects, which can be corrected using a plume abated cooling tower 

The Project

The Moorburg cooling tower, a huge project in Germany with one cooling tower for two units of 800 MW each, cumulates the advantages of different systems for an environmentally friendly purpose: limited visibility (small total height), limited ground surface, limited power consumption, low plume, and low noise emission.and noise reduction systems.

The Challenges

The owner's  first  idea was  to  build  a  classical wet  cooling  tower  above the  river.  The  tower  operation  was  in  open  circuit   mode.   This   project was  finally  rejected.  The tower   was  complicated, and  difficult  to  run  with the  variation  of  the  river water level. The  visibility  constrain  was  such  that  a natural draft  CT  could not be built in view of  its  height  and the emitted plume. A  classical  hybrid  cooling  tower  required  too much space to avoid the recirculation and could not fit in the allocated space. The  solution  that  finally  came  as  evidence  was  a round  hybrid  cooling  tower.  In  order  to  reduce  the power consumption, a fan assisted natural draft cooling tower was selected and as far as the noise limit is concerned,  the  tower  would have to  be  completely  protected with noise attenuators.

The Solutions

The  concrete  shell  has  an  hyperbolic  shape.  The total height is limited to 60 m to remain smaller than the boiler building. The bottom of the shell is perforated by 36 holes for the fans of the wet part. Above, at dry level, there are 36 square holes in the shell which include noise attenuators.  The cooling tower is divided into two independent    halves    corresponding    to    one unit  each. It can  be completely  isolated by quarters, air and water. The  water  flow  repartition  between  the  flumes was calculated with  CFD tools so that the design of the elbows could guarantee an even water supply to the distribution. To avoid the plume, the quality of the mixing between the oversaturated air coming from the wet part and the dry air coming from the dry part wasssential. Many  CFD  calculations  were  done  in  parallel with  model  tests  to  optimize  the  design.