The Ways of Recovering and Utilizing The Waste Heat of High Temperature Flue Gas During Dolomite Calcining

The dolomite calcination is one of the main part of the metal magnesium produced by silicon thermal method and dolomite calcining kiln is a kind of important magnesium production line equipment. High temperature flue gas and equipment heat radiation produced in the process of heat carried away a large amount of energy. If do not produce high heat flue gas recovery and utilization of the production process and the discharge flue gas freely, which not only pollute the environment but also waste of energy.

Due to the high-temperature flue gas produced in the process of dolomite calcining kiln calcination contains a lot of calories, Therefore, the magnesium production enterprises to try their best to find ways to carry out technical transformation and recover the rotary kiln flue gas according to the development trend of magnesium and technological requirements. There are two ways as following.
1 place a waste heat boiler at the tail of the rotary kiln and provide steam produced by waste heat boiler for the vacuum system of the jet pump.
Although the flue gas can be recovered by the waste heat boiler at the tail of the rotary kiln and some of the heat can be recovered, there are also some problems. The main problem is that a long flue is needed, flue insulation and sealing require more refractory and thermal insulation materials which lead to that investment increased. At the same time, due to the flue gas temperature drop will cause heat loss, in addition, the waste heat boiler flue gas temperature is still high, up to 300, So the rate using waste heat boiler flue gas heat utilization is low. there is another problem about shortage of steam or steam whereabouts. Therefore, the use of waste heat boiler to recover the flue gas heat is not the best way of energy saving.
2 Set vertical preheater at rotary kiln end and preheat dolomite with flue gas.
Adopt this calcining process not only makes the calcining time in the kiln be greatly shortened and productivity per unit area be greatly improved, but also can get higher activity of calcined dolomite thereby improve the return raterate of magnesium. Most new or technological transformation metal magnesium plant use this technology. From the point of of the enterprise feedback opinion, the vertical preheater of rotary kiln can low energy consumption of calcined dolomite from 270 kg / kg to 180kg/kg, 30% energy saving, and rotary kiln production capacity is increased by about 35%. This new type of rotary kiln is more energy saving than the ordinary rotary kiln, and the environmental protection index is better than that of the ordinary rotary kiln.
The heat is taken away by the high temperature flue gas of dolomite, which accounts for about 30% of the total energy consumption. The recovery and utilization of this part of the waste heat is very important for many magnesium production enterprises, there are two ways for waste heat utilization, the rotary kiln with vertical preheater equipment is more conducive to energy conservation and emission reduction. The magnesium plant can give priority to this method because high rate of heat utilization.