Annular Sleeve Lime Shaft Kiln

Product Details

The has the characteristics of low heat consumption, high lime activity, simple structure, and strong fuel adaptability. Compared with the traditional lime kiln, lime is calcined in the annular space, with more uniform airflow distribution, no cooling equipment in the kiln, a low failure rate, and easy maintenance. It is applicable to the production of high-quality lime by using coke oven gas, calcium carbide, and calcium carbide furnace tail gas in the steel industry and chemical industries. Automatic control is completed to improve the quality of lime and save energy, so as to calcine high-quality active lime.

1. Production capacity: Our company provides the design and manufacture of 150t/d, 300t/d, 500t/d and 600t/d annular sleeve kilns. The production capacity can be adjusted within a certain range and can achieve stable production without affecting the quality and consumption indicators.

2. Limestone particle size: 20~100mm, particle size ratio 1:3.

3. Fuel type: The kiln can use natural gas, coke oven gas, carbide furnace tail gas, fuel oil, etc. as fuel.

4. Lime product: The residual amount of C02 can be no more than 2% (24 hours average value), and the activity is more than 360ml (4N, HCL method for ten minutes).

5. Heat consumption: Use heat energy to the maximum extent, cool the hot air of the lime and inner sleeve, and part of the flue gas generated by combustion is sent to the calcination belt for circulation through the ejector. Under normal operation and nominal output conditions, the heat consumption of finished ash is not more than 930kcal/kg.

6. High operation rate: it can operate continuously for 48 weeks every year.

7. Calcination method: the combination of counter-current calcination and co-current calcination will not make the lime overburn, but also ensure the full decomposition of the lime and greatly improve the activity of the lime.

1. The sleeve kiln is composed of inner and outer cylinders. The inner cylinder and the outer cylinder are concentrically arranged to form an annular space, and the limestone is calcined in the annular area. The kiln body is divided into a preheating zone, countercurrent calcination zone, cocurrent calcination zone, and cooling zone from top to bottom.

a) The upper inner sleeve lower air inlet to the upper waste gas outlet of the sleeve kiln is the preheating zone, and 70% of the calcined waste gas passes through the preheating zone to preheat the stone.

b) A notable feature of limestone calcination in sleeve kiln is that countercurrent calcination and cocurrent calcination are carried out simultaneously. The two-layer combustion chamber distributed on the casing of the sleeve kiln divides the kiln body into two calcining zones operated in countercurrent and one calcined zone operated in parallel. There are two counter-current calcination belts from the upper combustion chamber to the upper end of the lower inner sleeve and from the upper combustion chamber to the lower combustion chamber, and the downstream calcination belt from the lower combustion chamber to the bottom of the lower inner sleeve.

c) The upper combustion chamber has an insufficient supply of combustion air for incomplete combustion, only about 50%. Under the action of the exhaust gas-induced draft fan, the incomplete combustion flue gas enters the upper material layer and meets the airflow from the lower part containing excess air, so that the incomplete combustion products can be completely burned. This area is the upper calcination zone. In this area, the airflow direction is opposite to the material flow direction. During countercurrent calcination, the limestone needs to absorb a large amount of heat at the initial stage of decomposition, so it generally does not produce over-burning.

d) The lower combustion chamber is full combustion, and the high-temperature flue gas (temperature<1350 ℃) generated by the lower combustion chamber combustion is divided into two streams: one stream flows through the middle calcination zone and the upper calcination zone to the kiln top and meets the incomplete combustion gas from the upper combustion chamber; the other stream flows downward under the action of the lower combustion chamber injector, forming a parallel flow calcination zone.

2. Co-current calcination is the key to the whole calcination process of the sleeve kiln, and the lime is finally burnt in this area. High-temperature flue gas calcines lime through the material layer and then enters the lower inner cylinder from the inlet of circulating gas uniformly distributed at the bottom of the lower inner cylinder: cooling air is sucked into the kiln from the bottom, and is preheated by high-temperature lime and enters the lower inner cylinder together with high-temperature flue gas from the inlet of the lower inner cylinder. The mixture of the two streams of air is called circulating gas (containing excess air which can be used as the secondary air for combustion), and the temperature is generally 800-900 ℃. The circulating gas flows through the lower inner cylinder inlet → the bucket injector at the top of the lower inner cylinder → the lower combustion chamber material layer → the lower inner cylinder inlet, and so on.

3. In the cocurrent calcination zone, with the material flowing downward, the CaO shell gradually formed on the limestone surface, and its heat absorption also became poor, but just at this time, the poorer fuel and air were in contact with each other for combustion. The heat supply is relatively mild, so the CaO shell will not be burnt, and the green core will continue to decompose.

4. The inner sleeve is divided into two parts, the upper inner sleeve is suspended at the top of the kiln, and the lower inner sleeve is located at the middle and lower parts of the whole . The upper and lower inner cylinders are made of boiler steel plates, with two layers in total. An annular gap is formed between the two layers. The annular gap is forced to be cooled by air. The inner and outer sides of the inner cylinder are lined with refractory materials. The refractory materials are mainly magnesia-alumina spinel bricks, high-purity mullite, high-alumina bricks, clay bricks, high-density clay bricks, etc., which are selected according to the different working conditions of the masonry parts.

5. Through the above design, the pressure, air flow and temperature in the kiln are evenly distributed in the annular section and the whole limestone material layer, ensuring the uniformity of limestone calcination, improving the quality of products, and reducing the unit consumption of products. Compared with the traditional lime kiln, the equipment is also more adaptable to raw materials.

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