New type dry process rotary kiln cement production line project with daily capacity of 2500t
Main process designing and devices for main machinery
1）Limestone breaking, conveying and storage. A MB56/75 model crusher (fix up in open) is used to break limestone. While the maximum incoming size of material ≤1500mm, and discharge size of granularity ≤75mm, the capacity of this crusher is 500～600t/h, discharging limestone is conveyed by belt conveyor into Φ80m round limestone pre-homogenization piles(storage 34100t) to be pre-homogenized and stored. The stocker (with piling capacity of 800t/h), cantilever, schort continuous cloth, bridge type reclaimer (capacity: 500t/h), head face taking material, center discharging. After being pre-homogenized, limestone is conveyed by belt conveyor to raw material batching station.
2）Assist to raw material storage, breaking and conveying. Assistant raw material sandstone and iron ore are conveyed to plant by carrier, discharged to open stock dump and stored. Specifications of open sandstone stock dump and open iron ore stock dump are 60 m×20m with storage of 5100 t and 32 m×20m with storage of 2730 t. Model PC1609 hammer breaker is used to break sandstone and iron ore. While the maximum incoming size of material ≤600mm, and discharge size of granularity ≤25mm, the capacity of this crusher is 50～70t/h. After being broken, the sandstone and iron ore are conveyed by belt conveyor to respectively batching stations of raw material batching station. Assistant raw material powder coal ash are conveyed to plant by bulk carrier, discharged by self-discharging system to coal ash batching stations of raw material batching station.
3）Raw material batching station. Raw material batching station includes four batching stations for limestone, sandstone, iron ore, coal ash (specifications are all φ12 m×25m, respectively storages are 2200，1600，2200，770t). Weighing feeders are settled at the bottom of batching station, giving out states mixture ratio material. Mixed raw materials are conveyed by belt conveyor into vertical grinding system to be grand.
4）Treatment of raw material grinding mill and waste gas. Model MLS3626 vertical mill (fix up open) is used as raw material grinding mill, its drying hot source comes from pre-heater’s waste gas. When the size of incoming raw material 90%≤75mm, fineness of production is 80μm, square hole sieve sifts it <12%, internal raw meal contains moisture <8% and out coming raw meal moisture is <1%, the system capacity is 185t/h (after abrasion). After being separated by pulverized-powder collector, out coming raw mill is mixed with fine powder collected by humidifier and electric dust collector. Then through the chute and bucket elevator, the mixture is conveyed to raw material homogenization warehouse to be homogenized and stored. The waster gas from mill is discharged into air after being treated by electric dust collector.
5）Raw material homogenization warehouse and raw material entering to plant. Qualified raw material out coming from mill, through top raw material silo distributor to model Φ18m ×50m raw material homogenization warehouse (with effective storage of 9000t ) to be homogenized. Then through discharging device discharges stated raw material into raw material entering plant system which equipped weigh storehouse with measuring and flowing control device under. Measured raw material is fed to kiln end pre-heater system by bucket elevator device.
6）Clinker firing system and storage. Clinker firing system is made up by low-pressure losing single series on line five stages pre-heater, decomposing furnace (model RF5/2500, with discomposing ratio >90%) and model LBT32216 Φ4.0×60m new control flow grate cooler, all of which is NCDRI technology.① The clinker out of kiln, after cooled by grate cooler, is conveyed by chain conveyor and tray conveyor to stored in 2-φ18×40m round storehouse. Then it conveyed by discharging device and belt conveyor to cement clinker out-transport and batching station. ② The hot gas from the hot end of cooler through third wind pipe to discomposing furnace uses as fuel gas of discomposing furnace. The partial hot gas from mid-warm end of cooler is led to coal mill as raw coal’s drying source. The waste gas from end is discharged into air after treated by electric dust collector with the dust consistency (standard condition) < 100mg/m3.
7）Raw coal storage and transport, coal powder preparation and transport. The raw coal conveyed by carrier to plant is stored and pre-homogenized by 21m×113m crane storehouse (with capacity of 9300t). There are two raw coal storehouses with weighing feeder under it. For one purpose is to short distance of crane, for another is to match two different quality coals. The coal is conveyed to coal mill by belt conveyor after weighed. Use model MPF1713 rolling disk coal mill (fix up open) for coal powder preparation. When feed moisture ≤10%, coal powder moisture ≤1%, raw mill feeding size ≤50mm, coal powder fineness is 80μm and square hole sieve sifts it <11%, the system capacity is 20t/h.Coal powder put of mill is led to air separator to be separated, after brought by airflow into gas-box pulse bag filter to be collected, the finished products are conveyed t two coal powder storehouses by spiral conveyor. Its waste gas is discharged into air after treatment. Under the coal powder storehouse, there is a weighing system. The coal powder is measured by this system then sent to kiln head and discomposing furnace.
8）Slag drying and conveying, gypsum breaking and conveying. Slag is transported to plant by carrier as mixture and discharged to the open pile, then shoveled by forklift to bucket elevator, and then to be dried in φ2.4×18.350m dryer with capacity of ≥30t/h (junior material moisture 20%, final moisture 1.5% ). Gypsum is transported to plant by carrier and discharged to open pile with capacity of 4000t. Later, heavy plate feeder feed it to PFC-1609 impact hammer breaker ( when feed size ≤600mm, out size≤25mm, its capacity is 50～70t/h ), the broken gypsum is conveyed by bucket elevator and belt conveyor to gypsum batching storehouse.
9） Cement grinding, conveying and storage. Cement batching station includes four batching storehouses for clinker, gypsum, limestone and slag. φ10 m×22m size clinker’s capacity is 2000t. Storehouses for gypsum, limestone and slag are in the size of φ8 m×22m,with respectively capacity of 800, 400 and 900t. Weighing feeders are equipped under each storehouse to give stated ratio of materials. There is a clinker bulking device beside clinker batching storehouse to transport out. The four materials given out in stated ratio conveyed by belt conveyor to two sets of circulating cement grinding system made up of Φ3.8×13m ball mill and high-efficiency air separator. When the cement surface reaches 3200～3400cm2/g, single system is 75t/h. Out material is conveyed by bucket elevator to air separator, meal is backed to be grinded in mill. Finished product is collected by gas-box impulse bag type dust collector then sent to eight φ15 m×34m cement storehouses (single capacity is 5300t) by air slides and bucket elevator. The waste gas of cement grinding system goes into high-efficiency gas-box impulse bag type dust collector to be treated then discharged into air. Outbound cement is discharged by bottom silo discharging system, then conveyed by belt conveyor bucket elevator and air slides to cement packing workshop and cement bulking silo. Two units of eight-mouth rotary packing machine with single capacity of 90t/h. The packed cements in bags are sent to 84m×30m cement finished products storehouse (with capacity of 6000t) by discharging system, also can be import cargoes transported. There are two cement cargo bulking devices under cement bulking silos for carrier bulking transportation.
Technical standard and main technique features
（1）Creative general arrangement. This project takes up the area of cragged hilly land besides limestone mine hill, without taking up farmland. General plan satisfies the smoothness of process design, meanwhile, considering the coming-out direction of raw fuel and cement production, as well as site terrain and surrounding transportation. From west to east arranges the fuel storage zone, main production line, planning obligate second-stage production line and plant front zone. All zones are arranged parallel, and each function is definite. The arrangement takes use of different height to device segments; view impression is artist and tidy. Besides, because the limestone mining hill is at west of plant, the raw fuel storage zone is arranged at west high place, which lessens the project quantities of site neat cubic meter of earth and stone, what’s more shortens the belt conveyor distance, rises earth operate factor and lows general project cost. In addition, in order to avoid the floodway in the central of plant, general plan arranges clinker production line and cement grinding system at two sides of it, and conveyed by belt conveyor, which satisfies process designing and reasonably uses terrain of plant, avoids the affection of floodway to the whole production line.
(2) Equipment choose fully reflects nationalization, advance, reliable, energy saving and high efficiency. For instance,
①using a set of national vertical mill as raw mill system, compared with traditional system, it has advantage of high efficiency, powerful drying capacity, low electric consumption, low cost, etc. Only in electric consumption, comparing with ball mill, its unit output saves electric 4～6kWh/t, annually saving 4.76 million～7.13 million kWh.
②cal coal mill is used instead of air swept ball mill, which saves 30% electric.
③Raw meal pre-homogenization silo is continuous with unit electric consumption of 0.3kWh/t, less 0.4kWh/t than intermittent raw mill mixer.
④ Firing kiln end is five stage cyclone pre- heater system with on line decomposing furnace. When raw meal enters kiln, the temperature reaches 900℃, and decomposing ratio is over 90%, the clinker firing hot consumption is controlled under 3137kJ/kg (750kCal /kg). Besides use new kiln head and kiln end sealing device, also adopt new high efficiency triple channel coal burner, through changing in-outside wind speed and volume ratio, flexibly control the fire shape and strength to meet kiln condition, thus, low the consumption of coal and rise the production. Controlling flow-push grate cooler cools clinker which has advantage of high hot recycling ratio and low energy cost.
⑥ High efficiency dust collector equipment is used, in order to be environmental, and low the discharging dust containing below national standard, which saves raw material, fuel and electric, and meets the purpose of energy-save, low-pollution.
⑦ Large scale blower and conveyor equipment are all energy- saving (such as using air slides instead of spiral conveyor), storage coefficient is not above prescriptive scale. Except raw meal entering pre-heater, coal powder conveyor, all conveyors for blocky and powder materials are machinery to save energy.
Production and practice proves: the new type dry process production line system technology of this project is mature and reliable, and the design is optimized. Debugging is smooth, and structure is reasonable, concise and artistic. Currently the annual working ratio reaches over 90%, average production is 2730t/d, clinker hot consumption ＜3136kJ/kg, the export temperature of pre-heater first stage silo＜338℃, resistance is 4590Pa. By checked, dust containing of all discharging point (standard condition) ＜70mg/m3, and the benefit is clear.
Jiangsu Pengfei Group provides under 8000t/d rotary kiln, as well as manufacturing, installation and debugging of complete sets of cement machinery. Pengfei brand main production: rotary kiln, ball mill, cooler, dust collector, dryer, breaker, vertical mill, fertilizer equipment.
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