What is pre-decomposition technology? The core of the new dry process cement plant is suspension preheating technology and pre-decomposition technology. The clinker pre-decomposition technology refers to adding a new heat source, precalciner, between preheater and cement rotary kiln. When the fuel is injected into the precalciner for combustion, the raw material preheated to about 750 ℃ by cement preheater is fed into the precalciner at the same time so that the exothermic process of fuel combustion and the endothermic process of carbonate decomposition in the raw meal is carried out rapidly. Generally speaking, the cement raw meal decomposition rate can reach more than 90% before entering the rotary kiln.
What is precalciner? Precalciner, also known as cement calciner, is a kind of high-efficiency direct combustion solid-gas heat exchange cement equipment. It disperses and suspends cement raw meal powder in airflow, making fuel combustion and calcium carbonate decomposition happen in a short time (generally 1.5 ~ 3 seconds). To some extent, it replaces part of the calcining work of a cement rotary kiln. In the calciner, because the fuel combustion and the material endothermic reaction are carried out at the same time, there is no visible flame, but in a state of low-temperature flameless combustion at 820 ~ 900 ℃.
Advantages of Appling Precalciner
- It is beneficial to reduce the heat load of rotary kiln, reduce the size of kiln, greatly improve the production efficiency, and save construction investment.
- It is conducive to the realization of large-scale cement production, reduces air pollution.
- The traditional method of adding all the fuel from the kiln head is changed to a small part from the kiln head and most from the calciner. It improves the thermal layout of the cement rotary kiln system.
- It moves parts of the carbonate decomposition process, which consumes the most heat in the process of clinker calcination, into the calciner to optimize the combustion, heat transfer, and carbonate decomposition.
- The applying of precalciner increases the output and running rate of cement rotary kiln and prolongs the service life of kiln lining.
- The use of precalciner is helpful to improve the utilization of low-quality fuel and has strong adaptability to raw materials and fuels containing alkali, chlorine, sulfur, and other harmful components.
Types of Precalciner
At present, more than a dozen types of precalciners have been put into use. Although each has its advantages, its characteristics and functions are similar. According to the different movement form of airflow, calciner in cement plant can be divided into four types:
Spiral-flow type calciner
The structure of spiral-flow type calciner is simple. The fuel and raw meal are swirling in the calciner.
Calciner with preheating chamber
This type of calciner is equipped with a preheating chamber, which can ensure the stability of fuel combustion and raw meal decomposition, but its structure is more complex.
Spouted calciner
Pulverized coal is usually used as fuel in the spouted calciner. Raw materials and coal powder are suspended in the calciner by hot gas jet.
Fluidized bed calciner
The tertiary air with a temperature of 200 ~ 250 ℃ is blown into the air chamber of the fluidized bed calciner by a high-pressure fan and then enters the inner chamber through the air cap so that the fuel and raw materials form a fluid-bed.
Working Principle of Precalciner
The preheated cement raw meal (temperature is about 820 ~ 860℃, not exceeding 860℃), a certain amount of fuel, and hot air (kiln tail flue gas or tertiary hot air) are fed into precalciner at the same time. After entering the calciner, the fuel and raw meals are dispersed by high-speed airflow and in a suspension state at about 900℃. The fuel is flameless combustion in the calciner, and the heat released by it makes the calcium carbonate in the raw meal decompose at a high speed through a convection heat transfer and radiation heat transfer. Generally, this decomposition process can be completed in a few seconds, and the decomposition rate of the whole raw meal is as high as 85% ~ 95%, forming an efficient operation mode of combustion, exothermic, endothermic, and decomposition at the same time.
Why Choose AGICO Precalciner
Why choose AGICO cement calciner? AGICO is a professional cement equipment and cement plant supplier.
- We offer precalciner customization service. We will design the outlook, capacity, and other equipment technical data according to customers’ needs.
- We produce advanced precalciner in cement plant. The precalciner produced by AGICO features automatic, large output, and long service life. We have a specialized research team, large production workshops, and professional production equipment to ensure the quality of our precalciners.
- We provide all-around service. AGICO provides attentive service from equipment manufacturing, installing, commissioning, operation training, to after-sales service.
Related Clinker Calcination Equipment
Precalciner forms the clinker calcining system in the new dry process cement plant together with cement preheater, rotary kiln, and cement cooler. In addition to cement calciner, AGICO also provides other high-quality clinker calcination equipment, such as cyclone preheater, cement rotary kiln, grate cooler, rotary cooler, etc.
