Optimization of coal distribution

Case study

Mill and ductwork

Initial situation

We found a customer with a coal fired power plant with several 600MW units commissioned in the 1970's each fuelled by six Steinmueller Medium speed, vertical spindle mills and a design efficiency of almost 37%. In reality the efficiency was far below design and emissions were high.

Unequal distribution of PF and Air

PROMECON was commissioned a survey for the coal distribution system which outcome was no surprise. The PF massflow distribution from the mills to the wall burners deviated up to 36% from the mean massflow. Furthermore the PF massflow was not proportional to the PF velocities, which clearly indicated a rope formation.

CFD of CE-Splitter before modification

Two phase CFD
Prior to design of the necessary changes of the ductwork a two phase CFD was performed for the existing installation. Goal of this simulation was to find the causes and possible indicators for system changes. The customer decided to improve the stations performance without design changes at the mills and the boiler. By using CFD once more, the engineered design changes for the ductwork were finally tested.

System Changes
MECONTROL Flow rope breaking devices and adjustable splitters are used to evenly distribute the PF concentration to the different pipes - adjustable trimming dampers retrospectively integrated to the pipes regulate the flow velocities.

PF flow monitoring system
The PF-massflow is monitored by a permanently installed MECONTROL Coal system which measures flow velocity and PF concentration with two independent measuring principles. Furthermore the air flows are also monitored using PROMECON technology.

Satisfactory results
After six months of project execution for system implementation, conversion of the ductwork and initial tuning, first results of operation are very promising. The powerplant now runs within design specifications and generates more energy than before. The cost for conversion will be amortised within the next year. Many problems which evolve insidiously can now be observed much earlier, which maintains a better availability of the plant. .

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