Cement production process can be summarized as raw material preparation, clinker combustion, cement grinding.The cement production technology of this project adopts advanced pre-decomposition kiln dry production technology, and its process flow is described as follows:
1. Crushing and pre-homogenization
(1) In the process of cement production, most raw materials should be broken, such as limestone, clay, iron ore and coal, etc.
Limestone is the largest amount of raw materials for cement production. After mining, the granularity is larger and the hardness is higher. Therefore, the crushing of limestone plays a relatively important role in the crushing of materials in cement machinery.
(2) The pre-homogenization technology of raw materials is to realize the preliminary homogenization of raw materials by using scientific stacking and retrieving technology in the process of storage and retrieving of raw materials, so that the storage yard of raw materials has the functions of storage and homogenization at the same time.
2. Raw material preparation
Cement production process, each producing one ton of Portland cement equipment grinding at least 3 tons of materials (including all kinds of raw materials, fuel, clinker, gypsum, mixture), according to the statistics, dry process cement production line of grinding operation need to consume power accounted for about 60% of the entire factory power, under the assignments need to consume of raw material grinding power accounted for about 60% of the factory to move the following, which accounts for less than 30% of raw material grinding, coal grinding accounted for about 3%, accounted for about 40% of cement grinding.
Therefore, reasonable selection of grinding equipment and process flow, optimization of process parameters, correct operation, control of operating system, to ensure product quality, reduce energy consumption has great significance.
3. Homogenization of raw materials
In the process of new dry cement production, the stable raw material composition into kiln is the premise of the stable clinker firing thermal system, and the raw material homogenization system plays the last role of the stable raw material composition into kiln.
4. Preheat decomposition
Preheat and part of the raw cement machinery decomposition are done by preheater, instead of rotary kiln features, to shorten the length of the rotary kiln, kiln at the same time heat transfer process of the gas accumulation condition material, moved to the inner state of suspension preheater, under slurry is able to discharge of hot gas well blended with stove, gas increases the contact area, heat transfer speed, high heat exchange efficiency, improve production efficiency, reduce the clinker calcining kiln system heat loss.
(1) Material dispersion
Heat exchange 80% in the inlet pipe.
Feeding the raw material in the preheater pipeline, under the impact of the high-speed updraft, the material turns to move up with the airflow and is dispersed at the same time.
(2) gas-solid separation
When the airflow carries the material into the cyclone cylinder, it is forced to rotate in the annulus space between the cyclone cylinder and the inner cylinder (exhaust pipe), and it moves downward while rotating, from the cylinder to the cone, which can be extended to the end of the cone, and then turns to rotate upward and rise, and is discharged from the exhaust pipe.
(3) Pre-decomposition
The emergence of predecomposition technology is a technological leap in the calcination process of cement equipment.
The decomposition furnace is set up between the preheater and the rotary kiln, and the fuel injection device is set up by using the rising flue at the end of the kiln to make the exothermic process of fuel combustion and the endothermic process of carbonate decomposition of raw materials. The decomposition rate of raw materials into the kiln is increased to below 90% in the suspended state or fluidized state in the decomposition furnace.
The original carbon salt decomposition task in the rotary kiln was carried out in the moving calciner;
Most of the fuel is added from the calcining furnace, and a small part is added from the kiln head, which reduces the heat load of the calcining zone in the kiln, prolongs the life of the lining material, and is conducive to the large-scale production.
Because the fuel and raw material are mixed evenly, the fuel combustion is timely transferred to the material, so that the combustion, heat transfer and carbonate decomposition process is optimized.
Therefore, it has a series of excellent performance and characteristics such as high quality, high efficiency and low consumption.
5. Cement clinker sintering
After the raw material is preheated and pre-decomposed in the cyclone preheater, the next step is to enter the rotary kiln for the clinker firing.
The further rapid decomposition of the carbonate in the rotary kiln and a series of solid reactions occur to form the iso-minerals in the cement clinker.
As the temperature of the material rises, such minerals will turn into liquid phase, which will be dissolved in the liquid phase for reaction to generate a large number of clinker.
After the clinker is burnt, the temperature begins to drop.
Finally, the high temperature clinker discharged from the rotary kiln is cooled by the cement clinker cooler to the temperature that can be sustained by the downstream transportation, storage and cement machinery, and the sensible heat of the high temperature clinker is recovered to improve the thermal efficiency and clinker quality of the system.
6. Cement grinding
Cement grinding is the final process of cement manufacturing, and it consumes the most electricity.
Its main function lies in the cement clinker (and the gelling agent, the performance adjustment material, etc.) grinding to the appropriate particle size (to fineness, specific surface area, etc.), the formation of a certain particle grade, increase the hydration area, accelerate the hydration speed, to meet the cement slurry condensation, hardening requirements.
7. Cement packaging
Cement factory has two kinds of delivery in bags and bulk.
