Annular Shaft Kiln originated in the sixty's of last century, Germany, formerly known as Beckenbach Annular furnace charge zone lime Vertical kiln, is a kind of lime vertical kiln, with two shafts, inner shaft and outer shaft. The raw material is calcined between the inner and outer shaft space.
Annular Shaft kiln technological process
Annular Shaft kiln inner structure from top to bottom is pre-heating zone, upper counter-follow calcining zone, lower parallel-follow calcining zone, and cooling / discharge zone. Raw material is screened firstly, then transferred to the top of the kiln by the hoisting hopper, and then feed into the kiln body by the rotary distributor evenly. Preheated raw material moves into the upper calcining zone along the annular furnace chargespace in where the raw material is effective in decarburization. The almost-finished lime in the upper calcining zone moves into the lower calcining zone for effective homogeneous, then moves down to the cooling zone, finally drops into the lime silo under the kiln by lime pusher platform. The finished lime transferred to the storage by the belt conveyer.
Main system equipment
A) limestone feeding and distributing system: lime stone hopper, weighing device, hoisting hopper, cable, electric winch, feeding device and rotary distributor, also limit switch, signal transmitter, hydraulic cylinder and hydraulic station.
B) lime discharging system: pusher platform, pusher rod, hydraulic cylinder and lime silo.
C) fuel distribution system: the fuel manifold, distribution branch pipe, related instruments and valves, online low calorific value analysis instrument.
D) exhaust system: exhaust pipe, exhaust fan (1set), bag dust collector, dedust fan (1 set), also relative valves, instrumentation, discharge chimney.
E) driving air system: driving air pipe, driving air blower (2 sets), heat exchanger, injector, also relative valves, instrumentation.
F) the inner shaft cooling air system: pipeline, blower (2 sets, 1 for use, 1 for preparing), also relative valves, instrumentation.
G) Combustion system: fuel and combustion pipeline, regenerative burner, UV (ultraviolet) flame detector, also relative valve, instrument.
H) Control system: MCC (motor control center), PLC, PC, and printer.
From the above system equipment, Annular Shaft kiln system is relatively simple, blowers are only six sets, and the permanent work ones are only five sets. This will bring the following advantages: 1, the system is simple, easy to operate; 2, less movable parts, saving electric energy; 3, low failure rate, high utilization rate, low maintenance cost, and low spare parts consumption.
Technical specifications
1) Daily output: 300 tons to 600 tons
2) Fuel: coal powder, natural gas, coke oven gas, converter gas, high / coke mixed or other mixed coal gas( the mini low heating value: 1200Kcal/Nm3)
3) Limestone particle size: 30mm to 80mm (large, small granularity ratio 1: 2)
4) Heat consumption: between 900~960kcal/kg lime
power consumption: 28Kwh/t lime
5) Lime quality: the activity >370ml (4NHCI, 5 minutes) LOI≤ 2.5%;
