Twin Shaft Lime Kiln

1. Product Overview

The Twin Shaft Lime Kiln (also known as Twin Shaft Parallel-Flow Regenerative Kiln / Maerz Kiln) is an advanced mainstream vertical lime calcination technology. It operates by alternate calcination in two interconnected vertical shafts to produce high-activity premium quicklime. Supporting multi-fuel firing, it is widely adopted by medium and large lime manufacturers with stringent quality requirements.

2. Core Performance Advantages

2.1 High Thermal Efficiency & Low Energy Consumption
Adopting alternate calcination and waste heat recovery, its thermal efficiency reaches 75%–85%, significantly higher than conventional single-stage vertical kilns (50%–60%).
• Natural gas consumption: 80–120 m³ per ton of quicklime
•Pulverized coal consumption: 120–150 kg per ton of quicklime
Fuel consumption is 20%–30% lower than single-stage vertical kilns.
2.2 Superior Environmental Performance
•Equipped with two-stage dedusting system: cyclone dust collector + baghouse filter.
•Dust emission ≤10 mg/m³, outperforming national standard limit of 30 mg/m³.
•Low-temperature air distribution and short-flame combustion design maintain NOₓ emission ≤300 mg/m³. No extra denitrification unit is required to meet emission standards.
2.3 Wide Raw Material Adaptability & Stable Product Quality
•Processable minerals: limestone, dolomite, magnesite, etc. Feed particle size: 20–80 mm. CaCO₃ fluctuation within ±5% imposes negligible impact on finished quality.
•Kiln internal temperature difference ≤50 ℃, delivering uniform temperature field. Quicklime activity ≥300 ml/4N-HCl. Underburning and overburning rate ≤5%. It achieves better quality stability than rotary kilns.
2.4 Compact Footprint & Low Capital Investment
Compared with rotary kilns of equivalent capacity:
•Floor area only 30%–50% of rotary kilns (e.g., a 300 t/d lime production line occupies approx. 800 ㎡).
•Civil engineering investment reduced by 20%–30%; equipment procurement cost cut by 40%–50%.
•Free of complex transmission assemblies. Installation cycle is merely 3–4 months, enabling fast commissioning for small & medium enterprises.
2.5 Reliable Operation & Low Maintenance Cost
Alternating operation eliminates persistent high-temperature zones. The service life of refractory kiln lining is 3–5 years, longer than the 1–2 years of rotary kilns. Critical components including reversing valves and burners have low failure rates, with annual operating hours exceeding 8000 h.

3. Working Principle

The kiln consists of Shaft A and Shaft B interconnected at the bottom of the calcining zone. Materials move downwards synchronously in both shafts.
Cycle 1: Shaft A as combustion shaft; Shaft B as regenerative shaft In Shaft A (combustion shaft), fuel and combustion air flow in co-current mode. Flame directly contacts cold feedstock for calcination. Flue gas and CO₂ released from limestone decomposition pass through the bottom crossover channel into Shaft B.
Shaft B acts as a regenerative shaft. Limestone absorbs waste heat from flue gas; flue gas cools down before discharge. The trapped heat preheats combustion air for the next cycle.
Cycle Reversal & Function Swap After reversing, Shaft B becomes the combustion shaft for calcination while Shaft A switches to regenerative heat exchange. By repeatedly swapping combustion and regenerative roles between the two shafts, continuous limestone calcination is maintained.

4. Application Scenarios

Ideal for large and medium-sized lime production enterprises with stringent quality control. It is suitable for the calcination of minerals such as limestone, dolomite, and magnesite.