Structure and process upgrading of rotary kiln in alumina roasting process Henan Hongxing


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Structure and process upgrading of rotary kiln in alumina roasting process

In alumina production process, roasting process is the key link, we need to have a comprehensive understanding of alumina roasting process to improve the process production in the production process. As we all know, alumina roasting needs to consume a lot of heat energy, which requires advanced equipment and energy-saving production Rotary kiln It is the key equipment in the process of alumina processing, so we study the energy saving of alumina rotary kiln.

The traditional alumina rotary kiln process design is simple, that is, aluminum hydroxide is sent to the rotary kiln, and combustible pulverized coal or gas is introduced from the outside. This kind of equipment has the advantages of simple result, convenient maintenance and high standardization strength. Traditional rotary kiln generally uses coal and natural gas as fuel, its energy consumption is large (generally 4.5-6.0 GJ / T), thermal efficiency is low (less than 45%), production is low, and fuel cost is high. Its advantages are that the velocity intensity of friction between particles is small, the product crushing rate is low, and the particle size is large. Therefore, we optimized the structure and process of alumina roasting rotary kiln.

 Alumina rotary kiln

Structure improvement of alumina rotary kiln

In view of the shortcomings of the traditional rotary kiln, the transformation is carried out to reduce the heat consumption, which mainly includes the following three improvements:

1. By changing the position of combustion device, the alumina rotary kiln of our company has achieved success after reasonable design of burner position. The production efficiency and energy saving of rotary kiln have been improved, with an average energy saving of 22%.

2. The rotary kiln was reformed by gas suspension roasting. After revamping, the capacity is increased to 1000t / D, and the heat consumption is reduced from 4.60 GJ / T to 3.66 GJ / T.

3. Rotary kiln with cyclone heat exchanger and fluidized cooler. Our company has designed a multi-stage cyclone cooler, at the same time using fluidized bed to cool alumina, the unit fuel consumption is reduced by 15% - 18%.

Process upgrade

It will be used in the production of alumina in rotary kiln. The so-called total oxygen combustion, pure oxygen in accordance with a predetermined fuel ratio, combustion in a more accurate way. Application advantages:

1. The amount of air needed for combustion and the amount of flue gas generated decreased, and the heat carried away by the exhaust gas decreased.

2. With the increase of flame temperature, the burn out rate of fuel increases.

3. The increase of radiation heat transfer intensity is beneficial to the effective utilization of energy and the rapid production of alumina.

4. The contribution of energy saving to the heat dissipation rate of the furnace is 2% ~ 2%.

5. The emission of pollutants decreased.

6. When oxy fuel combustion is used in alumina rotary kiln, the heat loss of flue gas and the heat dissipation of kiln surface are reduced, the burn out rate of fuel is increased, and the reaction temperature and radiation intensity in the kiln are increased. Considering all aspects, the total energy saving rate is 30% - 35%.

In addition to saving fuel consumption, oxy fuel combustion can help to reduce the air pollutant emission of rotary kiln and the operation cost of fans and other parts of equipment. Therefore, the application of oxy fuel combustion in alumina rotary kiln is successful in terms of economy and environmental protection.

Through the above optimization of the structure and process of rotary kiln, the efficient roasting processing of alumina can effectively avoid the disadvantages of traditional equipment and technology, and ensure the comprehensive improvement of production.

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