Processing & Equipments for Pre- disintegrate of active lime calcined by rotary kiln
1、Raw Material Conveying System
Limestone and dolomite after crushed the mine will be sent to factory floor, then they will be sent into raw material pit by forklift, next they will be lifted to raw material warehouse after screening and then the qualified 10-50mm limestone after metering will be sent into material bin on top of preheater by lifting equipment. The fineness of these material is 10-50mm thus, the the discharged finished granularity with 5-40mm could reach over 90%.
2、Active Lime Calcining System
Active lime calcining system composed of vertical preheater, rotary kiln and cooler.
1) Vertical preheater: Vertical preheater composed of preheater, storage warehouse, material feeding pipe, hydraulic handspike device. Preheater has polygons and round, which utilizing sub-depot and partition device which heat limestone gradually avoiding too quick warming-up causing implosion to crease a large number powder, disintegrate rate of limestone entering kiln could reach 30%-40%, average temperature of gas discharged could be 230℃∽260℃ for decreasing system heat consumption.
2) Rotary Kiln: Rotary Kiln composed of shell, supporting device, variable speed transmission device, thrust roller device, sealed device of kiln end & kiln head and cover of kiln head. Kiln body put aslant with the angle of 3.5% from horizontal level. It is equipped with two sets of supporting device, its roller bearings is water-cooled dipper lubricating sliding bearing with spherical surface W automatically aligning. And it is equipped with hydraulic thrust roller near to bull gear. Utilizes kiln body drove by variable frequency speed-adjustable motor, meanwhile equip with auxiliary transmission driving kiln body. In kiln head and kiln end takes use spring type sealed device. Utilizing kiln body drove by variable frequency speed-adjustable motor together with preheater disintegrating could efficiently control calcining time and temperature which could meet the crude burning or over burning requirements.
Burner takes use coal and gas mixture burning 4 channels burner which is convenient to adjust and easy to operate and the splashing speed of each wind channel could be adjusted during operation to meet the requirements of fire in different condition of kiln, thus it is easy to control the calcinning temperature.
3) Vertical Cooler: Vertical Cooler composed of cooler, fixed screening, cooling wind device, electrical vibrating discharger. Inside of vertical cooler are divided into many cooling discharge area, while discharging speed of each area could be adjusted according to temperature controlling; cool wind will directly meet hot lime inside of cooler, so the cooling efficient is good, ash temperature is low which is 40℃ higher of ambient temperature; cooling wind after cooling lime, its temperature could be preheated up to over 600℃, part of that will be used as 2nd combustion air, the other part will be used as drying powder. As there is no moving parts of cooler, the structure is simple, cooling effect is good, maintenance is less.
3.Coal Powder Manufacturing System
Coal manufacturing is the important part of active lime rotary kiln
system for utilizing coal. And normally there are two kind systems, one is powder manufacturing system composed of wind swept tube coal mill and bag type dust collector which has the advantages of convenient operation and environment clearance, etc.
The fineness of coal cinder which is no more than 25mm will be sent to belt conveyor, then belt conveyor will send them to raw material coal warehouse, and then they will be send into coal mill through disc feeder or electromagnetic vibrating feeder under raw coal bin, while the coal mill could not only fine grind but also dry the product through the hot gas of rotary kiln or hot smoke coming from auxiliary burner at the same time. The gas containing coal powder exhausted from coal mill will go into separator with the function of pull of exhaust blower. Rough coal powder after separated will return back to mill through automatic flash discharging valve for re-grinding, meanwhile fine powder will go into bag type dust collector with the function of airflow, thus has achieved the goal of separating powder and gas. The gas coming from separator will be treated by dust collector, then it will be exhausted by exhaust blower, while some waste gas will go into coal mill for circle using, the other waste gas will be exhausted into atmosphere through chimney。The coal powder collected by collector will be discharged coal powder storage bin of kiln head. According to the demand of coal powder bin, the coal powder will be send into burner of kiln head by one Roots Blower, then they will burn with the help of combustion fan of burner which will be used for limestone calcination.
4、Conveying System of Finished Products
Finished lime will go through cooler arriving chain bucket elevator, then it will be conveyed to elevator, and then it will be lifted into material bin in the top, after screening, the qualified granularity which is over 5mm will be conveyed to finished products warehouse through belt conveyor, meanwhile the powder material which is less than 5mm will be sent into powder warehouse. While thre are electric discharge valve under finished products warehouse and powder material warehouse. Here the function of finished products warehouse is buffer measurement and finished products should be sent to steel factory or calcium carbide for utilizing in time for reducing pulverization.
5、Smoke Treating System
Hot smoke created by burning of rotary kiln will exchange heat with limestone in preheater, then its temperature will fall down to less than 260℃, then it will go into high temperature bag type dust collector after being cooled by multi-pipes cooler, and last it will be exhausted into atmosphere by high temperature fan, at this time, the dust concentration of smoke is less than 30mg/Nm3.
In order to meet the processing requirements of modernized active lime pre-disintegrate rotary kiln production line, ensure reliable operation of processing equipments, stabilize progressing parameter, save energy and improve running rate of whole production line. The whole production line takes use advanced whole processing control, add the DCS control on the base of PLC control which could centralized monitor, centralized operate and decentralized control, as controlling operation system of rotary kiln could improve quality and reduce consumption. Improve the reliability and maintainability of electric control equipment for implementing modernization of controlling, monitoring and operation.
CaO≥93 , MgO≤4.5, SiO2≤1.0 P≤0.01 S≤0.025 igloss≤3 ，activity≥350ml∽380ml, crude burning≤1.5% ，over burning≤1.5% 。
Jiangsu Pengfei Group Co., Ltd