History & Development：
The annular shaft kiln was developed in Germany during the 1960s by Willmsheiler Company (Beckenbach) . Originally named the "Beckenbach annular charging zone lime shaft kiln," this design features a unique double-shaft structure consisting of an inner cylinder and an outer cylinder, with raw material calcined in the annular space between them . Since its introduction, this kiln type has been widely adopted worldwide due to its compact footprint, low heat consumption, uniform product quality, and excellent fuel flexibility .

Process Flow：
The annular shaft kiln is divided into four functional zones from top to bottom: preheating zone, upper counter-current calcining zone, lower parallel-flow calcining zone, and cooling/discharge zone .

The production process operates as follows:
Raw Material Feeding: After screening, limestone is transported by bucket elevator to the kiln top and evenly distributed into the kiln body through a rotating distributor.
Preheating: Material enters the annular space and is preheated by rising hot gases from the lower zones.
Upper Calcining (Counter-Current): Preheated material moves down through the upper calcining zone, where effective decarbonation occurs through counter-current heat exchange with ascending combustion gases .
Lower Calcining (Parallel-Flow): Partially calcined lime enters the lower calcining zone for uniform final calcination through parallel-flow heating, ensuring complete decomposition .
Cooling & Discharge: The calcined lime moves downward to the cooling zone, where it is cooled by rising air. Finished lime is discharged via the lime pushing platform into the kiln bottom lime silo, then transported by belt conveyor to storage bins.

Technical Specifications：

Key Features & Advantages：
Combined Calcination Principle: The annular shaft kiln uniquely combines counter-current and parallel-flow calcination within a single unit . The upper zone utilizes counter-current heating for efficient preheating, while the lower zone employs parallel-flow heating to achieve final calcination without over-burning—essential for producing high-activity lime.
Uniform Heat Distribution: The concentric double-shaft design ensures even gas distribution across the annular cross-section, eliminating "channeling" effects common in traditional shaft kilns and ensuring consistent product quality throughout the kiln .
Excellent Fuel Flexibility: Capable of utilizing a wide range of fuels including pulverized coal, natural gas, coke oven gas, converter gas, and mixed gases with calorific values as low as 1200 kcal/Nm³—ideal for steel plants with by-product gases.
High Product Quality: Produces lime with activity exceeding 370 ml (4N HCl, 5 minutes) and LOI ≤3%, meeting stringent requirements for steelmaking flux and chemical applications.
Efficient Heat Recovery: Waste heat from exhaust gases is recovered through integrated systems, contributing to low heat consumption of only 900–960 kcal/kg—significantly lower than many traditional kiln designs.
Proven Reliability: The annular shaft kiln design has been refined over decades, with hundreds of installations worldwide demonstrating stable operation, minimal maintenance requirements, and consistent product quality .

HBMER Advantage：
As a specialized lime kiln manufacturer, HBMER brings extensive experience and technical expertise to every annular shaft kiln project:
Custom-engineered solutions tailored to specific raw material characteristics and production requirements
Comprehensive service including design, equipment manufacturing, installation, commissioning, and operator training
Proven track record with multiple successful installations across various industries
Commitment to energy efficiency and environmental compliance
HBMER annular shaft kilns represent the optimal choice for producers seeking high-capacity, energy-efficient lime calcination with exceptional product quality and operational flexibility.