In 2009 Holcim Spain started a project to improve the pet-coke grinding in order to obtain safe and reliable coal mill feeding and to improve the coal mill grinding performance. The start-up of this installation took place in 2010. FLSmidth Pfister GmbH supplied the dosing equipment for the coal mill.
The project included the replacement of the mill’s old raw coal feeding equipment, which consisted of an apron feeder, by a new Pfister® TRW-K rotor weighfeeder.
The Pfister TRW-K installed in Carboneras is the first reference installation of raw coal and pet coke mill feeding in the cement industry. The know-how for this specific technology was transferred from the power generating industry where Pfister TRW-K rotor weighfeeder systems have been successfully in operation since 2003.
The Pfister TRW-K is based on the well-known and successful Pfister rotor weigh-feeder technology with more than 2300 units installed worldwide.
Application at Holcim Carboneras
The installation supplied by FLSmidth Pfister GmbH consists of:
• Vibrating hopper 1m³
• Shut-off gate
• Pfister TRW-K 4.18/5 rotor weighfeeder
Installation on site
The installation is a raw coal system feeding the coal mill. It consists of a 70 m3 hopper, in which the raw coal is stored. The vibrating hopper ensures a constant flow of the material. Installed behind the hopper is a dosing system (Pfister TRW-K rotor weigh-feeder) and a drag chain conveyor to the airlock at the mill inlet. The chain conveyors transport the material either to the mill inlet or to another feed point for truck transport. The Pfister TRW-K rotor weighfeeder is designed to feed up to 40 t/h of raw coal within a range of 10 - 100% nominal and a precision of +/- 1%.
Due to the EU’s ATEX requirements, the vibration hopper, shut off gate and Pfister weighfeeder are pressure shock resistant up to 3.5 bar.
Pfister TRW-K rotor weigh-feeder.
Holcim Spain has installed the first Pfister® TRW-Krotor feeder at their Carboneras plant, Spain, for dosing raw coal and pet-coke to the coal mill.
Technical characteristics and benefits of the Pfister TRW-K
The outstanding compact design of the Pfister TRW-K rotor weighfeeder requires minimum headroom. It also reduces maintenance work and extends service life owing to the following features:
There is no spillage that might affect operations or needs to be cleaned. Even sharp parts do not harm the feeder as is the case with a belt weighfeeder. Foreign bodies in the coal silo can be removed easily through service openings right next to the rotor weighfeeder inlet. All measuring parts are accessible from the outside. This makes repair and maintenance work very easy. Wear is minimal, because the parts of the rotor weighfeeder in contact with the coal are made of special wear resistant steel. Even burning coal can be fed. Minimal wear also results from the low speed of the rotor.
Holcim’s experience of operations
The Pfister rotor weighfeeder is a very reliable piece of equipment, robust and free of spillages. The exact and stable coal and pet-coke dosing improves mill grinding performance and reduces mill vibrations.
During the first three years of operation no major maintenance operations were necessary.
The spillage free operation and closed system significantly improves the safety of the installation.
The Pfister rotor weighfeeder is a good alternative for raw coal and pet-coke feeding and dosing.
All from one source
To maintain safe and reliable coal mill feeding, the stability and precision of raw coal dosing to the mill is essential. With its TRW-K rotor weighfeeder concept, FLSmidth Pfister is offering a future-oriented technology, with more than 50 units successfully in operation since 2003.
FLSmidth Pfister GmbH not only supplies the individual dosing machines. Its know-how also includes the complete setup and layout of the installation like silo engineering, intermediate material transport and safety equipment. This ensures that customers get all engineering from one experienced partner and one single source.
Since Holcim Carboneras installed their rotor weighfeeder, Holcim Cement Australia has also installed a Pfister TRW-K rotor weighfeeder at their coal mill, feeding 20 tph.
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