Anti-scaling innovation solution for FGD effluent evaporation
Calcium chloride evaporation crystallization technology
Calcium chloride is a commonly used inorganic compound. Depending on the production process, the soild usually appears in forms such as white granular, spherical, flaky, and powdery. It is easily soluble in water. Industrially, it is often used as a road de – icing agent, antifreeze agent, dust suppressant, desiccant, refrigeration coolant, and for other purposes. It also has application in industries such as agriculture, feed, and food. It is a product with wide – ranging uses. Classified by moisture content, it is divided into anhydrous calcium chloride and hydrated calcium chloride. The most common hyrated form is calcium chloride dihydrate.
The sources of industrial calcium chloride solution commonly used in China are by – products of chemical production or the neutralization of waste acid generated in chemical production with lime of limestone. The low – concentration calcium chloride solution, and then different calcium chloride products are obtained through different production processes. Due to the relatively high boiling point elevation of the calcium chloride solution, single – effect or double – effect evaporation is commonly used, and at most triple – effect evaporation.
Calcium chloride production process
For the production of calcium chloride, according to the production processes of different products, first, the low – concentration material liquid is concentrated to a relatively high concentration, then enters the slicing or granulation process, and finally is dried to obtain the calcium chloride product. The currently commonly used industrial production processes are:
Process 1
Concentrate the calcium chloride solution to a concentration close to saturation, and then enter the cooling slicer at a high temperature. During the rolling process of the drum of the slicer, the material adheres to the outer wall of the drum. Low – temperature circulating cooling water is introduced into the drum to cool the material, forming calcium chloride dihydrate slices with a moisture content of 4 – 5%. Then, they enter the drying system for drying to obtain flaky calcium chloride dihydrate products with a moisture content of less than 1%. This process has mature technology and a wide range of applications.
Process 2
Concentrate the calcium chloride solution to a certain concentration, and then enter the fluidized bed granulation system. The material is sprayed out from the atomizing nozzle and adheres to the surface of the seed crystal particles in the fluidized bed, and then is dried by high – temperature dry air to make the particles grow slowly. The dried product enters the screening machine. The particles with qualified enter the cooling drum for cooling as products and then enter the packing system. The particles with unqualified are returned to the fluidized bed as seed crystals. This is the mainstream process for currently producing spherical anhydrous calcium chloride,and high – purity anhydrous calcium can be obtained.
Project cases
Due to the relatively high temperature during the calcium chloride concentration process, as the main material, which can effectively extend the service life of the equipment. However, when the temperature of material liquid is too high, certain corrosion will also occur. Therefore, the temperature of the material needs to be strictly controlled during use.
