Fuel supply for ring-shaft furnaces in France

Dosing Machines for Lignite Dust Firing at Lhoist in Dugny

The “Carrières et Fours à Chaux de Dugny” plant in France, near Verdun, was founded in 1926 and marks the beginning of Lhoist’s international expansion. Today, the plant uses different fuels for lime production. In order to further reduce fuel costs, Lhoist partially converted three annular shaft kilns to lignite dust (BKS) firing.

Partial Conversion of Three Annular Shaft Kilns to Lignite Dust

Each kiln receives its own dosing machine as part of the conversion. Lhoist uses lignite dust exclusively for the lower firing level, while the upper level continues to operate with natural gas. Each level features four lances. These lances can be supplied with lignite dust independently, allowing flexible fuel distribution within the kiln.

For the three annular shaft kilns, Carbotechnik supplied a total of three DN1500 dosing machines. Each dosing machine features four individual dosing units. The individual dosing discs are designed for a conveying capacity of 100 to 300 kg/h each.

Dosing with Integrated Weight Monitoring

In addition, Carbotechnik equipped the dosing machines with load cells. This allows the operator to perform a weight check whenever required and, consequently, calibrate the fuel dosing system. As a result, the operator can reliably verify and adjust dosing accuracy during operation.

The conversion therefore provides a flexible solution for feeding lignite dust specifically to the lower firing levels of the annular shaft kilns, while natural gas continues to supply the upper level.

Furthermore, Lhoist plans to convert another identical kiln to lignite dust firing in the future. The existing Carbotechnik solution provides a suitable technical basis for this further conversion.