External circulation technology for VRM raw meal grinding
The pressure differential of a traditional vertical roller mill (VRM) system for raw meal grinding is high, with the fan accounting for about 45 per cent of power consumption. Sinoma International Engineering has developed external circulation VRM technology for raw meal grinding, whereby materials are transported by elevator instead of gas flow, leading to reductions in pressure differential and power consumption. By Du Xin, Nie Wenhai and Chai Xingteng, Sinoma International Engineering Co, Ltd, China.
Sinoma reduces pressure differential and power consumption at a cement plant in Guizhou province,
China, with its external circulation technology for raw meal grinding
When the VRM system evolved from an entirely-internal material circulation process to a partially-external circulation process, the pressure differential and gas volume were reduced by approximately 30 and 20 per cent, respectively. Therefore, power consumption of the grinding system decreased significantly. Following on, the move from a partially-external circulation process to an entirely-external circulation process has resulted in further pressure differential and power consumption savings. The development of the VRM process is shown in Figure 1.
