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As we all know, rotary kiln is divided into two categories, one is dry rotary kiln and the other is wet rotary kiln. What is the difference between the two types of rotary kiln? Today, Hongke machinery will explain it to you. After getting familiar with it, you can choose according to your own needs.
At present, there are two types of shaft kilns used in China: one is that the kiln barrel is horizontal (slightly inclined) and can rotate, which is called rotary kiln (also known as rotary kiln); the other is vertical kiln without rotation. Ordinary shaft kiln is manual feeding and manual unloading or mechanical feeding, manual unloading; mechanical shaft kiln is mechanical feeding and mechanical unloading. Mechanical shaft kiln is continuous operation, its production, quality and labor productivity are higher than ordinary shaft kiln. According to the requirements of building material technology policy, mechanized shaft kiln is used in small cement plant to gradually replace ordinary shaft kiln.
Cement rotary kiln is mainly used to calcine cement clinker, which can be divided into two categories: dry process cement rotary kiln and wet cement rotary kiln. Metallurgical and chemical rotary kiln is mainly used for magnetic roasting of lean iron ore in metallurgical industry; oxidation roasting of chromium and nickel iron ore; roasting of high alumina bauxite ore and clinker and aluminum hydroxide in refractory plant; roasting of chromium ore and chromium ore powder in chemical plant. Lime rotary kiln (i.e. active lime rotary kiln) is used to roast active lime and light burnt dolomite for iron and steel works and ferroalloy plants.
Type of dry process rotary kiln: the advantages and disadvantages of dry process rotary kiln are opposite to those of wet process rotary kiln. In dry process, raw meal is made into raw meal dry powder, and the moisture content is generally less than 1%. Therefore, compared with wet process, it reduces the heat needed to evaporate water. Due to the high temperature of waste gas, the heat consumption of hollow kiln is not low. In dry production, raw material is made into dry powder, and its fluidity is worse than that of mud. Therefore, the raw materials are not well mixed and the ingredients are not uniform.
Type of wet rotary kiln: cement kiln used in wet production is called wet kiln. Wet production is to make raw material into slurry with water content of 32% ~ 40%. As the slurry with fluidity is prepared, the raw materials are well mixed and the raw meal composition is uniform, which makes the clinker quality high, which is the main advantage of wet production.
Wet rotary kiln process: we only introduce and analyze the wet rotary kiln process. The kiln body of wet rotary kiln is usually relatively long (length diameter ratio is 30-40). In order to increase the heat transfer area of kiln, chains are often hung at the kiln tail to accelerate water evaporation. During the production of wet process rotary kiln, water is added into raw material mill to make raw material into rotary kiln with 30% - 40% water content. After homogenization, the slurry meeting the requirements is sent into the kiln by the kiln head feeder and calcined into clinker. The clinker out of the kiln is cooled by the cooler and sent to the clinker warehouse. The raw coal is dried and ground into pulverized coal and then burned to supply the heat needed for clinker calcination. The characteristics of wet rotary kiln calcination are as follows: raw material is made into slurry, so it has strong adaptability to heterogeneous raw materials, uniform raw material composition, stable process, high quality clinker, high clinker strength grade, less dust in grinding process and less fly ash at kiln tail. However, evaporation of 30% - 40% of slurry moisture in wet process requires a large amount of heat, which accounts for 1 / 2-1 / 3 of cement cost, which is higher than that of shaft kiln and dry rotary kiln. Due to the high heat consumption, high energy consumption, large water consumption and water consumption, wet cement production has been listed as the type of restricted and eliminated kilns in China.
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