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thyssenkrupp Ring Granulators – Effective coal crushing with a minimum of fines

thyssenkrupp Ring Granulators – also known as ring hammer mills – are ideal machines to crush coal to a suitable size in thermal power plants prior to pulverization. In addition to being used in power plants, they are also used in coal terminals to make the delivered coal loadable.

Typical installations include two redundant ring granulators, with one operating while the other one is on standby. Ring granulators are often fed by roller screens or vibro-feeders and the end product size can vary from around 20 - 50 mm depending on the application. The biggest model of thyssenkrupp Ring Granulators takes feed material up to 550 mm. After being processed in the ring granulator, the coal is ground in the final comminution process before being burned. Ring granulators provide consistent product sizes while keeping fines at a low level. They are characterized by low wear and energy consumption.

Ring Granulators by thyssenkrupp

Working principle of Ring Granulators

Ring granulators from thyssenkrupp are made up of four main components: the crushing chamber, the rotor, the housing and the drive. The crushing chamber consists of impact plates at the entry of the machine and screen cages at the bottom. The impact plates are installed in a way that the coal enters the crushing chamber tangentially. The screen cages have defined slots in order to ensure a constant product size and anti-clogging design. During operation, the gap between the screen cage and the hammer circle can be altered by changing the position of the screen cage. The rotor runs at an optimized speed to minimize wear and avoid generation of excessive fines. The rotor comprises the shaft, rotor discs and ring hammers. The rotor discs are keyed to the shaft and equipped with large size ring hammers, which are mounted on the rotor discs via ring axles. Ring hammers are available with toothed or plain design and can be replaced quickly.

Ring Granulators Working Principle

Customer benefits from Ring Granulators

Customers worldwide choose ring granulators from thyssenkrupp due to their high quality and operational safety. The ring granulators provide many advantages for the power generating industry, such as a low generation of fines, high reduction ratio, quick and easy exchange of wear parts, maximum crushing energy and long lifetime by optimized design of hammers, and optimized performance and wear compensation by adjustable screen plates, to name a few.

These characteristics demonstrate that thyssenkrupp ring granulators are ideally suited to the required comminution tasks in power plants.

Application of Ring Granulators in a power plant

The most recent installation of thyssenkrupp ring granulators is being carried out for a customer in the United Arab Emirates. The customer is currently constructing a 2400 MW coal-fired power plant. This plant will operate with two thyssenkrupp Ring Granulator RHM 0918 models (915 mm rotor diameter and 1830 mm width). The ring granulators will run at nominal capacities of 840 tph, with maximum capacities of 925 tph. For the ring granulators, the feed contains a maximum grain size of 150 mm. The product requirement from the customer is to produce P98 ≤ 50 mm.


thyssenkrupp Ring Granulators offer the following features for coal preparation plant operators:

  • Secondary crushing of coal
  • High reduction ratio
  • Low generation of fines
  • Easy maintenance
  • Low power consumption
  • Constant and clearly defined product size