150-300tpd Capacity Lime Project Limestone Shaft Vertical Lime Kiln
♣ Product Introduction of vertical lime kiln
Limestone and anthracite are transported to the transition silo on the top of the kilnby belt conveyor with scale , unloading car, and the elevator . The distributor on the top of the kiln will distribute the mixed limestone and anthracite into the kiln to calcine . The lime calcined will be discharged by the ash discharger , then transported to the finished lime silo by the belt conveyor to storage .
In the process of calcination, air is blows into the kiln to combustion by the blower . The gas with high temperature will preheat the raw materials , then will be discharged into the air after desulfurization and dust collect system by the draught fan.
According to the physical and chemical level of the materials and gases in the kiln, the kiln can be divided into 3 zones at the height of the kiln, namely, preheating zone, calcining zone and cooling zone
The preheating zone is located at the upper part of the kiln, which accounts for about 1/3 of the effective height of the kiln. The material in this region (limestone and anthracite) temperature by preheating from top-down normal temperature to about 900 DEG C, thus burning gas zone rising (kiln gas decreased from 900) up to 120 DEG C when the material after 900. The water in the material is completely evaporated, MgCo3 in the limestone have been the decomposition, the surface began to decompose, all the material and parts of mineral in coal has been broken down, so the area of the material was drying and preheating
The calcination zone is located in the middle part of the kiln body, which is about 1/6 of the effective height of the kiln body. The temperature in the area of raw materials from top to bottom up to about 1200 DEG C, and then decreased from 1200 DEG C to about 900 DEG C,the limestone is calcinated into lime, the anthracite calcinated into ash. In this area, the carbon in anthracite mainly reacts with oxygen in the gas to make the calcium carbonate in the limestone ore decompose and produce the finished lime
The cooling zone is located at the lower part of the kiln, which accounts for about 1/2 of the effective height of the kiln. In this area, the finished lime and cinder fall from about 900 to about 60, while the gas in the kiln rises from the normal temperature to about 900 centigrade. To reduce the material from about 900 DEG C to 60 centigrade, carbon remaining can not burn .the calcium carbonate in limestone residual is no longer decomposition, in the cooling process. While the gas in the kiln rises from normal temperature to about 900 DEG C, the main process of gas is preheated
The preheating zone and the cooling zone are all heat exchange zones, and the gas temperature in the preheating zone is too high, and the heat is transferred to the material with low temperature (limestone, raw coal and anthracite). The material in the cooling zone (finished products, lime and cinder) is high in temperature and transfers heat to the lower temperature gas (air). This will make the furnace heat efficiency to a higher level.
♣ Main features of the lime shaft kiln
1. A Wide range of product reactivity, due to easy adjustability of operating temperatures
2. Large stone size range
3. High flexibility in adjusting the burning zone temperature
4. Low impurity level in the product, e.g. sulphur or fluorine
5. Suitable for gaseous , liquid and solid fuels
6. Low investment cost per ton of product due to high specific output per M2 of shaft cross section
7. All kiln parts designed for transportation in containers
8. All structural steel designed for easy erection with reduced welding work
♣ Working Process of the lime shaft kiln
The raw material to be calcined is charged at the top of the kiln. It it then pre-heated by the combustion gases in the counter-current before reaching the burning zone. In the burning zone the material is calcined by means of fuel introduced together with primary combustion air through radially arranged burner lances. Cooling air is introduced at the discharge part of the kiln to cool the product in a counter-current manner. The heated cooling air travels upwards to the burning zone and is used again there as the secondary combustion air.
From the top of the kiln he exhaust gas are directed to a dust collecting system.
♣ Lime shaft kiln main parameters
| Basic Parameter of Lime Shaft Kiln |
| Number |
Parameter |
Units |
50T/D |
100T/D |
200T/D |
300T/D |
400T/D |
| 1 |
Inner Diameter |
Meter |
2.4 |
3.6 |
4.8 |
5.3 |
5.3 |
| 2 |
Outer Diameter |
Meter |
3.6 |
6 |
7.2 |
8 |
8 |
| 3 |
Effective Height |
Meter |
16.5 |
24 |
30 |
30 |
34.5 |
| 4 |
Total Height |
Meter |
22 |
32.3 |
39.8 |
38.3 |
42.8 |
| 5 |
Efficient Power |
KW |
60 |
90 |
120 |
130 |
150 |
| 6 |
Total Power |
KW |
135 |
186.5 |
206.5 |
260.5 |
283.5 |
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