With the continuous development of cement production technology, the production limit of cement plants is also increasing. Nowadays, cement plants with a clinker capacity of more than 5000 tons per day are gradually becoming the first choice of many cement manufacturers. As a cement plant designer and builder, AGICO has accumulated a lot of experience in large-scale cement plant construction projects, and developed 4 design principles more suitable for large cement plants.
1. Building Site Selection
When selecting the construction site for a cement plant, both raw material supply and marketing should be considered. In the past, the idea of putting a complete cement production line in the same plant site is gradually changing into the idea of building clinker and cement projects separately, that is, the clinker production line is built close to the limestone quarry and the cement grinding plant is built close to the target market.
To construct the clinker production line near the quarry reduces the transportation cost of raw materials and lowers the risk caused by the supply of raw materials. The clinker production line should also be built in a location with convenient transportation, such as places near the river or port, so that the clinker produced can be transported to grinding stations or exported by cheap waterway, which greatly reduces its transportation and sales costs and enhances its market competitiveness.
Constructing the grinding station near the market allows the production to quickly adapt to market fluctuations. In addition, the grinding station near the sales market helps to establish a good brand image and makes customers feel your products are safe and reliable.
2. The Design of Raw Material Pre Homogenization
In the design of large cement plants, there are always pre-homogenization yards for raw materials, especially for limestone. However, due to the large daily consumption of limestone in the large cement plant, the blasting time interval is greatly shortened in the mining process, and the limestone has been consciously matched in the mine production, which naturally includes homogenization. Therefore, in large cement plants, the storage function of the limestone pre-homogenization yard weighs heavier than the pre-homogenization function.
Large rotary kiln has strong adaptability to raw materials, and its sensitivity to homogenization is not as high as that of small rotary kiln. So the real function of a limestone pre-homogenization yard is to act as a buffer between the limestone crushing system and the raw meal grinding system. In general, if the time of replacing a pair of hammers of the crusher is 1d, then 3d will be enough for the designed capacity of the pre-homogenization yard.
In large cement plants, the long pre-homogenization yard has more advantages because of its expandability. But its track width should be controlled within 40m, otherwise, the rigidity of the reclaimer girder will face serious challenges. The number of stacking layers is not necessary to design as many as 400 layers, and the speed of the stacker can be slowed a little, but the storage yard must be equipped with emergency access, which can be used in the maintenance of the reclaimer.
Another design idea is to set the limestone batching scale directly under the reclaimer and cancel the limestone batching silo to reduce the intermediate links and improve the operation rate.
3. The Design of Raw Material Grinding System
Cement plants are usually designed with raw material grinding systems with low energy consumption, especially the vertical roller mill (VRM), which is the first choice for large cement plants. Due to the large power consumption of large cement plants, the use of a vertical roller mill can obtain an obvious power-saving effect.
In the vertical roller mill system, no matter whether the electric dust collector or bag dust collector is used, there must be a cyclone to pre-collect the dust-containing gas from the mill, so as to reduce the load of the dust collector and improve the gas emission standard.
4. The Design of the Calcination System
As the core system in a cement plant, the calcination system is designed according to principles of advanced technology, energy saving, and environmental friendly.
The technology of our calcination system is very mature and has reached the international advanced level. Moreover, the new generation of the calcination system is more adaptable to raw materials and fuels. In the past, it was considered that the calorific value of raw coal should be greater than 22990kj to meet the requirements of the precalciner kiln, but now it only needs 18810kj or even lower, which greatly reduces the cost of raw fuels.
Our low-temperature waste heat power generation technology without supplementary combustion is also very mature, which provides a good technical support for the energy-saving design of cement plants. In the past, the waste gas from the calcination system was directly discharged after humidification, cooling and dust collection, and the rest heat was not recycled. Now, the application of this technology can make the waste heat power generation of one ton of clinker reach 36 ~ 40kwh.
Conclusion
AGICO has always been trying to improve the design scheme of large-scale cement plant projects, striving to build cement plants with reliable performance, advanced technology, energy conservation and environmental protection for clients.