3000tpd New Type Dry Cement Production Line/cement plant
- TECHNICAL SPECIFICATIONS
1.1 PRODUCTION SCALE AND CEMENT TYPES
Production scale: 3000 t-clinker/d
Cement types: Ordinary Portland Cement (GB175-1999 Chinese standard)
1.2 RAW MATERIALS AND PROPORTIONING
Raw mix exercises were conducted to determine the suitability of the different materials for manufacturing Pozzlona Portland Cement and Ordinary Portland cement. Following limiting values for clinker should be considered.
| Parameters |
Limiting Values |
| C3S (%) |
55 -60 |
| C3S+C2S (%) |
80 |
| C3A (%) |
6 - 16 |
| LSF |
0.90 - 0.98 |
| SM |
2.20 - 2.80 |
| AM |
1.0 - 1.5 |
| Liquid phase (%) |
26 - 28 |
| Alkalies as Na2O eqv |
< 1.0 |
2 PRODUCTION PROCESS
2.1 Brief introduction to process flow
a) Limestone crushing & conveying
The limestone is discharged into the receiving hoppers in front of the crushers via self-unloading trucks. Through the apron feeder, limestone is fed into a hammer crusher. The crushing capacity is 700 t/h with a maximum feed size of ≤1200 mm and a discharge size of ≤75 mm. Then limestone is sent to the limestone preblending stockpile via belt conveyor together for preblending and storage.
b) Corrective crushing &conveying
The corrective with particle size £500mm are discharged from automatic dump truck into a crusher. The crushing capacity is 200 t/h. After crushing, they are sent to corrective preblending storage.
c) Limestone preblending storage
The limestone preblending will adopt circular preblending stockpile with chevron stacking. The limestone will be set in piles with reserve of 25,000t. The cantilever stacker will be used for continuous stacking, and scraper will be adopted for end face reclaiming. After preblending, the limestone will be conveyed to raw material proportioning station by belt conveyors.
d) Corrective and coal preblending storage
After being crushed by corrective crusher gypsum, clay will be stacked into a stockpile . the iron ore, corrective and coal will be directory to the hopper after crusher. The material (iron ore, clay, corrective ) will be reclaimed by a side scrapper reclaimer with the capacity of 200 t/d and conveyed to raw material proportioning station and the coal will be reclaimed by a side scrapper reclaimer with the capacity of 200 t/d and conveyed to cement mill feeding system(gypsum,etc.) by belt conveyors. ,
e) Raw materials proportioning station
There will be four raw material bins (one is a standby bin) in the system. Limestone, clay, iron ore in raw material bins will be discharged, weighing and then will be adopted in raw material proportioning system. Weighing feeders are installed under the proportioning bins supplying for dosing and feeding of various materials according to preset ratio. Then the raw-mix will be conveyed via belt conveyor into roller mill system for grinding.
f) Raw materials grinding
Vertical Roller Mill (VRM) of capacity 270 tph will be used for drying and grinding of raw materials. The high-temperature gas from the cyclone preheater is utilized as drying heat source. The VRM will be equipped with high efficiency dynamic separator. The ground raw meal will be air swept and collected through the high efficiency low-pressure drop cyclones. The roller mill shall be equipped with bucket elevator for external recirculation. Product fineness shall be 12 % residue on 80 micron sieve with a moisture content of not more than 1%.
Ground raw meal shall be transported to the top of homogenizing silo with the help of air slides and belt bucket elevator. Vent gases from the raw mill circuit, shall be dedusted in a bag filter and the dust content in exhaust gas after bag filter will be less than 30 mg/Nm3 of dust. Kiln dust will be transported to raw meal silo also or to the preheater together with kiln feeding material directly.
Gas from the cyclone preheater will enter ID fan, and then will be separated two ways in output of ID fan, one way will enter bag filter and the other will enter raw mill. During the stop of the raw mill, the kiln gas will directly enter bag filter after cooled down by a quenching fan. After being dedusted in bag filter the gas is emitted by draft fan and chimney.
g) Homogenizing silo and kiln feeding of raw meal
One Φ18m continuous homogenizing silo with the capacity of 10,000 t will be considered for storing and homogenizing of raw meal. Raw meal shall be extracted by two flow control gates and fed to Kiln feed bin which located under the silo. Raw meal from kiln feed bin shall be extracted through a set of shut off gates and dosing equipment. This material will also be weighed and than be fed to air slide feeding kiln feed bucket elevator. A belt bucket elevator will be provided for lifting the raw meal to pre-heater top.
h) Preheater, kiln, grate cooler system
The raw meal will be burned to clinker in a six stage preheater, precalciner and the Ø4.3×60m rotary kiln with the capacity of 3000t/d. Low pressure drop, high efficiency preheater cyclones are installed.
After preheated and decarbonation in five stage preheater and precalciner, the raw meal with decarbonation rate of ≥90% will go into the kiln, continue be decarbonated and be burned into clinker. The clinker out of the kiln will be cooled by grate cooler and conveyed by pan conveyor to clinker silo for storage.
Rotary kiln system equipped with variable speed drive will be provided. There are burners respectively set for kiln and precalciner. Part of the high temperature air from the hot end of cooler will go into the kiln as secondary air, and part of it will be introduced into precalciner through tertiary air duct as burning gas. New generation cooler with horizontal air cooling system will be offered. Offered cooler system will be imported from the third country. The exhaust gas emitted from cooler will be dedusteded by an EP and then emitted to the atmosphere through stack with dust content is <30mg/Nm3.
i) Clinker storage
Apron bucket conveyor is envisaged for collection of clinker from cooler. A two-way gate is envisaged at the discharge of apron conveyor for diverting unburned clinker into unburned clinker bin with a capacity of 1,000 t. Normal clinker is transported to clinker silo for clinker storage. A Φ45m silo is applied for clinker storage with effective capacity of 45,000t. The clinker out of clinker silo is sent to clinker bin at cement proportioning station by belt conveyor.
j) Cement grinding
Three proportioning bins provided with belt weigh feeders for the extraction of materials will be provided for cement mill system.
Two closed circuit ball mill cement grinding systems, each capable of producing 90~95 TPH of cement at 3400 Blaine will be provided for finish grinding. The fresh feed shall mix with rejects from the air from the high efficiency separator and forms the total feed to the mill. The mill discharge shall be conveyed by bucket elevator to the HES. The separator removes the product while the coarse rejects are recirculated back to the mill for further grinding. A mill bag filter is provided for venting of cement. Cement collected in the filter, will be transported to the cement silo with the help of air slides and belt bucket elevator.
k) Cement storage and Packing
Four RCC constructions, cement silos of capacity 5,000 ton are envisaged for cement storage. Cement bulk loading is also possible with the bulk loading facilities. Three bulk loading system will be provided.
Two packing machines will be offered for packing cement in paper bags. Packed bags will be transported to four manual truck loading machines.
l) Compressed air station
A complete compressed air system is offered to provide utility air, fabric filter cleaning air, instrument air and so forth. Utility air compressors will be furnished with oil and moisture separators.
The compressor(s) will be screw and water cooled. The utility, and dust collector cleaning air compressors will be centrally located in one compressor room. There are two compressors in it. It's volume is 20cubic meter per minute and it's discharge pressure is 0.75MPa. Air dryers of refrigeration type and capacity will be provided to remove the excess moisture in the compressed air and to ensure that service air quality meets the specified requirements. Air drier will be provided individually for each compressor.
The compressor room will be provided with an electrical traveling hoist capable of lifting the heaviest part or sub-assembly.
Main compressed air header will be provided from the centralized compressor house to various consumption areas and interconnected with the existing compressed air network. Air pipelines will be above ground level (overhead).
m) Pulverized coal preparation
A vertical mill with a high efficiency separator will be used for raw coal grinding and drying. The nominal capacity of the mill is approx. 26t/h of coal pulverized at 12% reject at 90 microns.
The raw coal silo will be equipped respectively with a high measuring level and an emergency high level sensors. Bin and extraction must be dedusted. The raw coal will be adjusted by weigh-feeders. A metal separator and a metal detector are installed before the raw coal is fed to the vertical mill to eliminate metallic parts. The dust collected by the filter will be the qualified coal meal, which will be transported either to a bin for kiln or to a bin for precalciner. The air from the filter will be sent either to the chimney or partially or totally recycled to the coal mill air inlet. A fresh air inlet with damper will also be included in the mill air circuit. The design dust concentration in the dedusted gas will be lower than 30mg/Nm3.
cooler exhaust gases will be used to dry the raw coal in the vertical mill. No auxiliary air heater is requested.
The coal meal extracted from the bins by two sets of weighing and feeding systems will be pneumatically transported to the kiln and precalciner burners. The capacities will be 8~10t/h for the kiln burner and 10~12t/h for the precalciner burner. The transporting air is supplied from air blowers.
The workshop will also include necessary isolation dampers, explosion valves, CO and temperature detection, inertization by CO2, and etc.
o) Water supply
The plant will have 4 water supply systems for water circulation system, spray water living water and fire fighting water. The water pipelines will be laid underground according to adopted standards and will be protected from corrosion outside and inside.
In order to save water, cooling water for production equipment will be circulated. Cooling water will be supplied to production equipment through circulation pump and the water returns to cooling tower by its remaining pressure. After being cooled down, the water will flow back to the circulation tanks. Equipment cooling water will be circulation water, but water spraying for raw mill, exhaust gas conditioning tower and clinker cooler will come in a independent pipelines network from a spray water tank. Where water needs high pressure such as water spraying for conditioning tower and cooler etc., water pumps and tanks will be adopted for secondary pressurization.
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