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RWE Innovation Centre – Reducing mercury emissions using lignite coke
RWE Innovation Centre – Reducing mercury emissions using lignite coke

Development of an industrial-scale demonstration unit at lignite power station BoA1

Reducing mercury emissions using lignite coke (HOK®, German: Herdofenkoks)

Two versions of process: “dry” in continuous operation/ “wet”

"Demonstration system for mercury reduction"

  • The purpose of the demonstration system is to refine and perform long-term testing of innovative versions of procedures to reduce mercury emissions in flue gas from lignite/coal-fired power stations using lignite coke (HOK®) in continuous, automated operation
  • Full-scale system at a flue gas train at the BoA1 lignite power station in Niederaussem, volumetric flow of flue gas approx. 1.6 m3N/h
  • HOK® supply for “wet” and “dry” versions from shared silo container
  • Expansion of mercury system to supply both flue gas trains at BoA1 in subsequent commercial operation
  • Project executed by the technical services of RWE Power and RWE Technology International
  • Contractor: ISS Schüttguttechnik GmbH
  • Demonstration operation since beginning of 2019

Dry version includes:

  • Dosing and simultaneous distribution to 16 nozzles via pneumatic delivery lines
  • Delivery supply and compressed air supply
  • Variation of injection speed for optimum penetration depth and even distribution of HOK®
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Dry version includes:

Wet version includes:

  • HOK® mixture with water and wet grinding in a stirred media mill
  • Buffer container, reservoir and loop line system to 16 nozzles
  • Variation in particle size
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Wet version includes:

R&D programme by RWE to reduce mercury emissions

Optimising of all power stations, but with focus on lignite

What is HOK®?

  • Lignite coke or activated coke (HOK®) is produced from Rhenish lignite using the hearth refining process.
  • HOK® has a large specific surface area and a favourable pore radius distribution, with a large proportion of mesopores and macropores.
  • The pore diameter of 1 to > 50 nm enables easy access to the inner surface.
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