twin shaft kiln lime production solution

Twin Shaft Lime Kiln

Production Capacity: 200 – 800 t/d

Heat Consumption: 850-900 kCL/kg

Lime Activity: 350-400mL

Application: Active lime production, quick lime production.

AGICO Twin Shaft Lime Kiln

AGICO has independently developed and designed an improved twin shaft lime kiln based on internationally advanced technology. The maximum production capacity of a single kiln can reach 800T/D. It features energy efficiency, environmental protection, high lime activity, and low over-burning rate, making it highly suitable for medium and small-scale production of high-quality lime.

The twin shaft kiln, also known as the twin shaft parallel flow regenerative lime kiln, is an advanced lime calcination equipment. It consists of two interconnected kiln chambers, one for calcination and the other for heat storage, with a passage connecting them. The working states of the two kiln chambers are generally alternated every 12 to 15 minutes. This kiln type adopts the advanced parallel flow regenerative calcination principle, where combustion air, fuel, and materials all flow downward from the upper part of the calcination zone. Their flow directions are the same, allowing for gradient combustion of the materials, thereby avoiding over-burning. Additionally, the materials converge with the cooling air in the cooling zone, leading to rapid cooling and thus enhancing the lime’s activity.

twin shaft lime kiln project

AGICO Twin Shaft Kiln Features

Large Lime Production Capacity

AGICO can design and construct twin shaft lime kilns with a production capacity ranging from 300T/D to 800T/D. The operational flexibility of the twin shaft kiln ranges from 70% to 100%. Taking the example of a twin shaft kiln with a designed capacity of 600T/D, its actual production capacity can be adjusted arbitrarily between 420T/D and 600T/D, while still achieving stable production without compromising the quality of lime or energy consumption.

High Lime Production Efficiency

The twin shaft lime kiln employs direct heating, where the high-temperature gases generated by combustion directly contact the limestone, accelerating the decomposition reaction of the limestone and enhancing both lime production capacity and efficiency. This technology produces high-quality lime, with a lime activity of 360ml, potentially reaching up to 400ml, and residual CO2 content of ≤2%.

Energy-Saving Lime Production

The twin shaft kiln is currently the most energy-efficient type among all lime kilns. The flue gas generated inside the calcination chamber enters another chamber through a flue, preheating the materials in the preheating zone, thereby allowing for efficient heat recovery. The materials can be preheated to around 800 degrees Celsius, and the combustion air can be preheated to around 650 degrees Celsius, improving the heat efficiency and saving energy.

Outstanding Environmental Performance

The twin shaft lime kiln adopts a closed structure and is equipped with high-performance flue gas treatment equipment. The exhaust gases generated during combustion are treated before being discharged, reducing atmospheric pollution. Additionally, the collection chamber at the bottom of the lime kiln effectively collects and treats the lime produced, reducing waste and environmental pollution.

Twin Shaft Lime Kiln Working Principle

The twin shaft kiln utilizes two chambers, A and B, for lime calcination, with both chambers interconnected at the bottom of the calcination zone, allowing materials to descend through both chambers. During the calcination process in Chamber A, combustion air and fuel flow parallel to the material, allowing the hot flame to come into contact with the materials with lower temperature and high heat absorption capacity. Consequently, the relatively lower-temperature combustion gases come into contact with the gradually calcining materials, achieving uniform calcination conditions and higher thermal efficiency.

The products of combustion and CO2 released from material decomposition enter Chamber B through a connecting passage. At this stage, Chamber B functions as the heat storage chamber, where the limestone in the chamber absorbs heat from the exhaust gases. Simultaneously, the exhaust gases are cooled to lower temperatures, and the materials absorb heat, which is then used to heat the combustion air for the next cycle of combustion. In this setup, Chamber A serves as the combustion chamber, demonstrating parallel flow characteristics, while Chamber B demonstrates heat storage chamber characteristics.

In the subsequent cycle, the chambers exchange roles, with Chamber A becoming the heat storage chamber and Chamber B becoming the combustion chamber. This continuous exchange allows for the continuous calcination of limestone.

AGICO twin shaft lime kiln working principle
twin shaft lime kiln designed structure

Automatic Production by PLC

The operation process of the dual chamber lime kiln adopts a PLC (Programmable Logic Controller) to achieve automatic centralized control. This system can monitor the operation status and parameters of equipment related to production operations in real-time, such as temperature (including kiln chamber temperature, flue gas temperature, ash discharge temperature), pressure (combustion air pressure, cooling air pressure, spray gun cooling air pressure, kiln chamber pressure, etc.), flow rate (including various air flow rates, etc.), limestone weight, silo material level, and valve position of each valve body, and achieve control over the fuel conveying system, air supply system, and feeding system The monitoring of the loading system, unloading system, hydraulic system, and reversing equipment ensures the safe and normal operation of the lime kiln.

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