This design adopt rotary kiln to produce active lime. Used for 100-1000t/d active lime production line.
1、 Product
1.1Capacity
The designed capacity according to requirement, the capacity range between 100-1000t/d.
1.2Product specification and standard
Product quality reach the first class degree required by national standard (YB/T 042-2004) . The active lime physical and chemical index should conform below standard:
| Degree |
CaO |
MgO |
SiO2 |
S |
Lose of weight on Ignition |
Activity/mL |
| Super class degree |
≥92.0% |
＜5.0% |
≤1.5% |
≤0.020% |
≤2% |
≥360 |
| First class degree |
≥90.0% |
≤2.0% |
≤0.030% |
≤4% |
≥320 |
Product Size
The active lime burned by Rotary kiln, the lime size less than 50mm.the final product size confirmed according to customer requirement, such as the electric furnace steel making use the active lime with size 20-100mm,,converter steel making use 5-50mm active lime, sintering use the lime size generally less than 5mm, this design according to final product size less than 50mm,if the customer need the even smaller lime size, then it needs to add lime screen and crushing equipments.(note: this design not including the crushing and screening devices after the rotary kiln, if need, pls let us know).
2. Raw material and requirement
The raw material use to produce lime is carbonate rock, use the CaCO3 as the main chemical component, generally called lime rock or limestone, also can use the dolomite.
Limestone physical and chemical index
| Category |
Model |
chemical component(mass ratio %) |
| CaO |
CaO+MgO |
MgO |
SiO2 |
P |
S |
| not less than |
not big than |
Common limestone |
PS540 |
54.0 |
- |
3.0 |
1.5 |
0.005 |
0.025 |
| PS530 |
53.0 |
1.5 |
0.010 |
0.030 |
| PS520 |
52.0 |
2.2 |
0.015 |
0.060 |
| PS510 |
51.0 |
3.0 |
0.030 |
0.100 |
| PS500 |
50.0 |
3.5 |
0.040 |
0.150 |
Magnesium limestone |
GMS545 |
- |
54.5 |
8.0 |
1.5 |
0.005 |
0.025 |
| GMS540 |
54.0 |
1.5 |
0.010 |
0.030 |
| GMS535 |
53.5 |
2.2 |
0.015 |
0.060 |
| GMS525 |
52.5 |
2.5 |
0.030 |
0.100 |
| GMS515 |
51.5 |
3.0 |
0.040 |
0.150 |
Limestone size requirement
Limestone particle size ratio refers to the ratio of limestone biggest size and smallest size. Generally is 2:1-3:1.
The size of limestone for rotary kiln calcinations is alternative from 10-50mm.
3.fuel
Rotary kiln lime calcinations can use the coal powder, coal gas, natural gas or heavy oil as the fuel. The requirements of different fuel as below:
3.1 Coal powder
；
Volatile content generally require the coal volatile content big than 15%,less than 25%.
；
Ash content generally require the ash content less than 10%, the ash content melting point big than 1250℃.
Water content there are little difference according to ball mill's different requirement, generally not exceed 12% water content.
Sulfur content generally require the coal sulfur content less than 0.8%.
Fineness generally speaking, coal powder fineness of bituminous coal is R88 =10-20%,
coal powder fineness of anthracite coal is R88 =5-10%
3.2 Gas fuel
It can adopt natural gas, coke oven gas, producer gas or mixed gas as the fuel.
3.3 Heavy oil
4. Technical flowchart introduction
Active Lime Rotary Kiln Production Line Schematic Diagram
1- feed valve 2- vertical pre-heater 3-rotary kiln 4-burning device 5- vertical cooler
6- forced draught fun 7-raw material discharge device 8- electrostatic dust collector
9-smoke outlet
4.1 Raw material storage and transport.
Clean limestone with 20-40mm size was transported to factory, then store in the raw material storage area, the raw material from the bottom of material tank via vibrating feeder was feed into the vibrating screen through high inclined angle belt conveyor. After screening, the qualified product above 10mm will be fed into the raw material tank on the top of the preheater, less than 10mm will be regards as the waste.
(note: if the raw material is the non-crushed limestone, it needs to add limestone crushing and screening system; if needed, then add limestone wash devices. this design equipments details including limestone crushing system, if no need, then point out specially.)
4.2 Limestone calcination
Limestone calcination system is composed of vertical preheater, rotary kiln and vertical cooler,
The preheater is the multi-bin structure, the raw material was feed into preheating tank of the preheater itself from the silo on the top of the preheater via raw material discharge chute, the higher temperature from the tail of the rotary kiln feed into preheater, then the limestone will undergo precalcining inside the preheating tank. Around the preheater there are many hydraulic raw material pushing device, then the pushing device move in turns, then push the well-preheated raw material out of preheating tank, then enter the turning chute. The raw material will be fed into rotary kiln via the turning chute. The smoke temperature enter the preheater around 1100℃, then penetrate the raw material layer, carry out the heat exchange with the limestone, the limestone preheated temperature can reach 800-900℃,then the 30% limestone will decompose, the waste gas discharged temperature generally lower than 220℃,adopt the vertical preheater calcination system will enjoy the higher surplus heat utilization, not only recovery big quantity heat value, and benefit for lifting the rotary kiln temperature, higher lime activity. Vertical preheater enjoys the better preheating effect, less running devices and stable operation.
Limestone enter the tail of rotary kiln, the burning system is located at the head of rotary kiln and provide heat value. Under the rotate and incline function, the limestone flow from the rotary kiln tail to the rotary head, after calcination inside the rotary kiln then become the active lime.
The lime after higher temperature calcination inside the rotary kiln then discharge into vertical cooler via rotary head. The cooler separate into four cooling area, and composed of one center air cap and four air distributors. The cooled air blast by high pressure centrifugal fan enter separate cooling area via wind duct, then have the heat exchange with the raw material, after the raw material becoming cooler and cooler and the temperature higher above 40℃ while compare with the surrounding environment then discharge from the cooler, the heat exchange can make the air temperature increase to above 600℃, then feed the twice time high temperature combustion air. Every area wind volume can be adjusted to ensure cooling effect.
4.3 Finished product transport
The finished lime after discharged by the cooler then was transported to the finished lime tank by chain type conveyor delivery via bucket elevator.
4.4 Smoke and environment protection treatment
The high temperature smoke generate by the burning of rotary kiln, while have the heat exchange with the limestone inside the preheater, the temperature decrease to below 220℃,then feed into bag type dust collector via the smoke duct, after dust collect, high temperature fan and then exhaust to atmosphere, the dust content should be less than 50mg/m3. If the smoke temperature is too high, then it can open the cold wind valve to mix the cold wind to lower the smoke temperature before enter dust collector to avoid temperature too high and result in the burning of the bag.
The dust generate by rotary kiln tail cooler discharge the raw material and material tank discharge, then feed into the bag type dust collector via the dust collect cover, after purified then exhaust to atmosphere.
Dust collector collect the dust mainly are lime, then transported to the finished lime tank after well collected.
4.5 Burning system
Rotary kiln burning system difference lies in the different fuel. Generally include burner, fuel transportation, air transportation and monitor & control part. if use the coal powder as the fuel, it need to add the coal powder making system.
Coal powder making system including raw coal transportation, raw material feeding, milling, dust separate, collect and control system and so on. The qualified raw coal was transported to the raw coal tank via the bucket elevator, the vibrating feeder feed the raw coal into the coal ball mill evenly, then milled into fine powder. exhausted coal powder was feed into the separator via airflow to carry out the separation, the non qualified size return to coal ball mill for regrinding, the qualified coal powder flow into the maximum concentration dust collector with the airflow, collected coal powder feed into coal powder tank. The coal powder transported to the coal powder tank. Coal powder inside the coal powder tank feed into the coal powder burner via measuring tank.
4.6 Automatic control system
Rotary kiln active lime production line adopt the fully automatic control system. The main production line adopt computer control, then realize the monitoring and control inside the central control room, the devices controlled by the computer control system located in the separate electric room.
：
Main testing and control content:
（1）
The raw material feeding system control automatically, after the raw material level testing inside the raw material tank on the top of the preheater, control the start and stop of feeding and transporting.
（2）The automatic control of preheater, control hydraulic station and raw material pushing device speed, adjust raw material feeding quantity.
（3）The automatic control of rotary kiln, adjust the rotary kiln rotate speed, monitoring kiln temperature and pressure.
（4）Vertical cooler system control.
（5）Smoke dust collector system automatic control, monitoring temperature, pressure, wind speed and other index, adjust fun rotate speed, cold wind mix quantity control and so on.
（6）Coal milling system automatic control; rotary kiln head coal feeding system control.
（7）Industry TV monitoring system.
5. Manpower
The management, administration, logistic of this project three biggest system can carry out the factory class, workshop and team management system. For the three shifts continuous work for weeks position, according to station present regulation, every week work five days and have labors rotate by turns, the administrative staff can carry out allocation and add according to company situation.
