Project Site: Shandong, China
Equipment: 4 MTW215 European Mills (Secondary Phase) and other auxiliary machines used for feeding, powder preparation, dust removal, powder collection, transportation, storage and nitrogen protection
Finished Product: Coal powder
Input Size: ＜50mm
Output Size: 200meshes, D80
Model of Efficient & Clean Use of Coal under Depression of Coal Industry
In response to national’s advocacy on clean use of coal, an energy company in Shandong purchased 4 MTW European Mills (secondary phase) for coal powder preparation from ZENITH. Through atomization of micro-coal, the coal will be supplied to industrial boilers as fuel. The use of coal powder can increase the combustion efficiency and thermal efficiency of boilers greatly and bring economic profits as much as hundreds of millions yuan. Undoubtedly, this is the model of efficient and clean use of coal.
Design Scheme --- Installation and commissioning
The energy company is a research and development base focusing on the efficient and clean use of coal in Shandong Province. The technology of micro coal atomization, its result of independent research and development, can boost the transformation and upgrading of coal industry effectively. The so-called micro coal refers to the coal powder meeting the standard of fineness after coal is ground by mills. Through the technology of micro coal atomization, the fuel can mix with air fully to form a rotary vortex and then the fuel enters the industrial boilers and burns in suspension inside. The use of thermal system, monitoring and controlling system and exhaust purifying system achieves the efficient combustion with emissions reaching the emission standards of gas. Except for the increase of input-output ratio, the clean coal production which used our 4 MTW215 European Mill (Secondary Phase) and other auxiliary machines reduced the emission of dust, SO2 and nitrogen oxides greatly.
According to the report released by China National Coal Association, over 70% coal companies are suffering financial losses. The severe situation of coal industry makes transformation and upgrading urgent. So, under the premise of controlling coal consumption, how to increase economic profits of tradition coal firms, how to use coal resource efficiently and cleanly and how to reduce environment pollution incurred by coal combustion have been the common problems among coal companies.
(1) Depression of Coal Enterprises
According to the report released by China National Coal Association, over 70% coal companies are suffering financial losses. The operation faces difficulties and the situation of this industry is severe. Meanwhile, China actively advocates and supports the market-oriented reform and structural management in coal industry by releasing related policies. Under the condition of balancing supply and demand, it is urgent for coal industry to upgrade.
(2) Support of National Policies
The Action Plan of Clean Use of Coal (2015-2020) released by China National Energy Bureau clearly stipulates that by 2020 the use ratio of efficient boilers must reach 50% at least in some areas. According to the fifth plenary of CPC’s 18th Central Committee, the clean use of fossil energy must be put on the schedule, coal included. So it can be concluded that the promotion of efficient and environmental coal powder boiler will be a key energy-saving technology in China.
(3) Support from Local Government
To stimulate transformation and upgrading, Shandong government subsidized some major PPP projects. Meanwhile, Shandong province launched an action plan (2015-2018) to promote efficient and environmental coal powder boilers. The plan showed that the efficient coal powder boilers can be used for heat supply and steam supply and therefore the boilers should be popularized and applied as soon as possible.
(4) Environmental Pressure
Using coal briquette as the fuel, traditional industrial boilers discharge a great deal of dust and contaminant. However the use of coal powder makes local area free from pollution with all emissions below the national standards. The emission of dust is ≤30mg/m3, SO2 ≤100mg/m3, nitrogen oxides ≤200mg/m3.
(5) Economic and Environmental Profits Brought by Combustion of Coal Powder
The use of coal powder boilers can burn over 98% of coal powder. Meanwhile, compared to the traditional boilers, the coal powder boilers can save energy by over 30% while heat efficiency keeps above 90%. The operation costs can be reduced by 20-30%. What’s more, the unit cost of fuel of coal powder boilers occupies one third of that of gas boilers only.
Configuration of Production Line
Main Equipment of Coal Preparation System
4 MTW European Mills (Secondary Phase)
The complete system of MTW Series European Mills is advanced. The mill is equipped with the bevel gear integral transmission device, inner thin-oil lubrication system, monitor of oil temperature. Meanwhile, the mill boasts small occupation of land, low total investments, low operation costs, high efficiency and environment protection.
Compositions of Coal Preparation System: Raw material bin, weighing coal feeder, MTW European Mill, powder collector (anti-explosive dust collector), fan, de-iron separator, drying system, conveying system, etc.
Auxiliary Machines of Coal Powder Preparation
1. Nitrogen Making System
Firstly, air is compressed by air compressor. Then air enters the efficient oil remover where most oil, water and dust would be removed primarily. After that, the refrigerated-typed air-dryer removes most moisture and the powder filter removes the dust. Then the air enters the air storage tank. After buffer, the air is sent into the nitrogen making machine filled with absorbents. Clean compressed air enters to the adsorption tower from the bottom and then the air diffuses under the action of air diffuser. In the adsorption tower, the oxygen and nitrogen would be separated and the nitrogen would be sent to the tank for storage.
2. Fire Extinguishing System
When the temperature in the protection area is beyond the preset-value, the alarm signal will be transmitted to the alarm which sends directives to the alarm bell and the bell works. So does the CO. When the content of CO is beyond the preset-value, the alarm starts to send signal to the audible and visual alarm. Then the alarm counts down for 30s. When it counts down to 0, the alarm will send signal to the CO2 fire extinguishing system which is started to extinguish the fire.
3. Pneumatic Conveyor
Pneumatic conveyor is mainly responsible for the transportation of coal powder. It can send the coal powder into the finished product bin from a long distance.
4. Intelligent Centralized Control System
Through multiple communication technologies to read PLC or ECS and collect the operation situations of equipment and through directives to control the equipment, centralized control system can achieve remote control, record and analysis of machine operation and print the reports of equipment operation.
MTW European Mill has specialized intelligent control system. It takes ESC to control operation intelligently. And apart from the central control, it can control operation remotely. By communication tools like smart phones and Ipad, the operation situation of production lines can be checked out.
Raw coal is sent by quantified feeder to the scrapper conveyor which then sends coal to the dryer for moisture removal. Then the coal enters the closed storage bin through closed scrapper conveyor. The coal is then transferred to the raw material bin of powder preparation system and by weighing coal feeder the coal is fed into MTW215 European Mill. After that, the coal powder undergoes the classification and following this step the coal powder enters into the powder collector along the tube (The remaining air is collected by impulse dust collector). The finished coal powder collected enters the elevator under the action of spiral conveyor. Finally, the coal powder is elevated to the coal powder storage bin. And if there is any need, the finished coal powder will be transported by the tanker. The complete set of this system is equipped with the nitrogen making system and CO2 system to avoid explosion and to extinguish the fire if necessary. Meanwhile, anti-explosive valves are installed at the key parts in avoidance of possible damage to the equipment.
(1) Turnkey Project
To save construction time and investment costs, the coal powder preparation system took the EPC service. EPC service belongs to a turnkey service specially designed and offered to bring convenience to our customers. The service covers every and each stage of a project including the topographic survey, design of production line, test of raw material, the analysis of requirements on finished product, calculation of investment costs, installation of machines, and commissioning, etc. It helps customers avoid some unnecessary problems like the insufficiency of building materials and labors. EPC service makes the operation more convenient and it is available for those customers who need put production into operation in a short time. BTW, this customer from Shandong spoke highly of our EPC service after he chose the service.
(2) Easy Operation
To make the operation of the coal powder preparation production line easier, we took unique two-step method. Specifically, the two-step method refers to the solution which separates the drying process and powder preparation process. The relatively cooler grinding cavity is the special technology owned by MTW European Mill. The system is simple and easy to be controlled, which guarantees the safe operation to some extent.
Compositions of System: Storage bin of raw coal, Dryer, Weighing coal feeder, MTW European Mill, Impulse dust remover, Powder collector, Fan, Storage bin of finished coal
9. Storage bin of coal powder 10. Monitoring system 11. Centralized control system
(3) Low Investments
The MTW Series European Mill is equipped with the bevel gear integral transmission device, inner thin-oil lubrication system, monitor of oil temperature. Meanwhile, the mill boasts small occupation of land, low total investments, low operation costs, high efficiency and environment protection.
(4) Safe and Environmental
To ensure safe operation during the coal powder preparation, the production line is equipped with nitrogen making system and CO2 fire extinguishing system in avoidance of explosion and fire accidents.
Meanwhile, some effective measures are taken to control the emissions. The content of dust meets the stipulated standards. The use of advanced impulse dust collector reduces the negative impact on surroundings.
Analysis of Profits
(1) Analysis of Economic Profits
The atomization of micro coal can increase the combustion ratio to 98%, the thermal efficiency to 90%. Besides, steam production can be increased from 5.5 tons to 9 tons. Compared to the traditional industrial boilers, the clean coal powder boilers can save coal by 30%, electricity by 20%, water consumption by 10%, floor space by 60% and labor force by 50%. The sales volume of clean coal powder attains 800 million yuan and 100 million yuan of taxation of profit is got.
(2) Analysis of Social Benefits
The clean coal powder produced in this production line is supplied to the industrial boilers after the atomization of coal powder. It reduces the combustion of lump coal and urges coal industry to transform and upgrade. It is the model of clean use of coal.
(3) Analysis of Environment Benefits
All emissions met the standards of gas boilers, helping the environment protection.
This clean coal powder preparation production line was large and the requirement on quality of coal powder was quite strict, so we were very careful when we chose the machine manufacturers. After various inspections and analysis, we chose ZENITH. From the site survey to the commissioning, ZENITH offered us professional solutions and services. The 4 mills we purchased are running stably and the yielding is beyond our expectations.
Introduction of Micro Coal Atomization
The key of this technology is atomizing micro coal by mixing it with the air vortex repeatedly. Mixing the micro coal (200meshes) with the high-speed air vortex is the first step. The mixture will be sent into the boilers and burn in suspension there. The use of thermal system, monitoring and controlling system and exhaust purifying system achieves the efficient combustion with emissions reaching the emission standards of gas.
Through selection, drying and grinding, the micro coal used in the efficient coal powder boilers can become the powder (200 meshes). Centralized management and unified delivery not only ensure the quality of coal powder but also eliminate the scattered coal piles. The boilers are characterized by high efficiency, environment protection, clean emission and high automation. Therefore, the promotion of efficient coal powder boilers plays an important role in clean use of coal, environment improvement and the growth of environment-friendly industries.