An energy company in Shandong purchased four MTW European Grinders (phase-II) from ZENITH for pulverized coal production. By means of pulverized coal atomization technology, the pulverized coal is used to be the fuel of the industrial boilers, which remarkably improves the combustion efficiency and thermal efficiency of the boilers. The yearly revenues amount to more than RMB 100 million. And this project becomes an example in the efficient and clean coal utilization field.

Project Background

According to a report of the China Coal Industry Association, the industry situation is really severe, with nearly 70% coal enterprises suffering a loss, and the transformation of the coal industry is extremely urgent. Therefore, on the precondition of controlling the total coal consumption volume, how to improve the economic benefits of traditional coal enterprises, how to utilize the coal resource efficiently and cleanly, and how to reduce the coal pollution to the environment have become the studying issues of numerous enterprises.

Severe Situation of Coal Enterprises

Recently, a report released by the China Coal Industry Association revealed that nearly 70% coal enterprises suffered a loss and were under difficult operation and the industry situation was extremely urgent. Meanwhile, the central government is actively boosting the marketization reform and structural adjustment of the coal industry from the policy level. Therefore, on the precondition of clearing the supply-demand relationship, the transformation of coal industry is extremely urgent.

Support from National Policy

The Action Plan of Clean and Efficient Coal Utilization (2015~2020) recently released by the China National Energy Administration clarified the key tasks in 7 aspects. Of them, one is that by 2020 the use of high-efficiency boilers in some regions must account for over 50 percentages. The 5th Plenary Session of 18th National Congress of CPC brought forward the boosting of clean and efficient utilization of fossil energies, including coal. It can be learnt that the high-efficiency and environmental-friendly pulverized coal boiler is a key energy-saving technology project promoted by the central government.

Support from Local Government

Boosting the transformation with financial policy, Shandong government provided subsidies for the earlier stage expense of key PPP projects. In addition, Shandong government issued the notification for the High-Efficiency and Environmental-Friendly Pulverized Coal Boiler Promotion Action Plan (2016~2018) to mainly apply the high-efficiency and environmental-friendly pulverized coal boilers in the gas and heat supply fields, to implement the “Five-One Project” properly, and to speed up the promotion and application of high-efficiency and environmental-friendly pulverized coal boilers.

Environmental Pressure

The traditional industrial boilers are fueled by block coals so that the emissions of soot and pollution gases are high. If fueled by pulverized coal, the boiler can realize the emissions of ≤30mg/m3 soot, ≤100mg/m3 sulfur dioxide, and ≤200mg/m3 nitric oxide, which are lower than the national emission regulation and meet the local stringent environmental requirement.

Economic and Environmental Benefits of Pulverized Coal Combustion

When a traditional coal-fired boiler is reformed to a pulverized coal boiler, the pulverized coal burn-off efficiency is higher than 98%, the boiler’s operating thermal efficiency higher than 90%. The fuel-saving capacity is higher than a traditional boiler by 30%, and the comprehensive operation cost reduction is up to 20~30%. The fuel procurement cost for the unit heat value of a pulverized coal boiler is only approximately 1/3 of that for a natural gas boiler.

Performance Standard

Customer address: Shandong

Applied equipment: Four MTW215 European Grinders (phase-II) and supporting feeding, pulverized coal production, dust extraction, pulverized coal collection, conveyance, storage, and nitrogen protection devices.

Processing material: Coal

Finished product: ＜50mm

Particle size of finished product: 200 mesh 80% sieve pass rate

Production capacity: 1,000,000 tons per year (Phase-II)

Configuration of Production Line Equipment

Main Equipment of Pulverized Coal Production System

Four MTW European Grinders (Phase-II)

The MTW series European Grinder system is a new generation grinding machine of world’s advanced level. This machine adopts multiple advanced technologies, including integral bevel gear drive, internal thin oil lubrication system, and oil temperature online measurement, and boasts multiple proprietary patented technological property rights, characterized by small occupation area, low comprehensive investment, low operating cost, high efficiency, and environmental protection.

System composition:

Raw material bin, enclosed constant weight feeder (optional), MTW European Grinder, pulverized coal collector (explosive-proof precipitator for coal grinder), fan, de-ironing separator, drying system, and conveyance system.

Auxiliary Equipment of Pulverized Coal Production System

Nitrogen Generator System

The air is compressed by the compressor and, after a majority of oil, water, and dust is removed by the high-efficiency deoiler, a mass of water content is removed by the refrigeration type compressed air drier, and the dusts are removed by the dust fine filter. Then the air is buffered by the air reservoir and enters into the pressure swing adsorption oxygen-nitrogen separation system (namely nitrogen preparation unit) filled with absorbent. The clean compressed air is fed from the bottom of absorption tower and, after being diffused by the air diffuser, the air is inputted evenly into the absorption tower. After the oxygen-nitrogen absorption separation, the nitrogen is outputted from the outlet and enters into the nitrogen stabilizing tank.

Fire Extinguishing System

When the temperature within the protection zone exceeds the preset alarm temperature value, the alarm signal is transmitted to the alarm unit which sends a command to the alarm bell to start alarming. The CO concentration alarm signal is also connected to the fire alarm unit via signal wire. When the CO concentration exceeds the preset alarm concentration, the alarm unit sends a command to the sound-light alarm to start alarming. Then, the alarm unit starts the 30s countdown. When the countdown is completed, the alarm unit sends a signal to the CO2 fire extinguishing system so that the nitrogen starting cylinder battery opens the corresponding solenoid valve and the nitrogen starts the CO2 fire extinguishing system to extinguish the fire for the alarm zone. The system has four control modes, namely automatic, manual, mechanically emergency manual, and emergency start/stop modes.

Pneumatic Conveyance System

The pneumatic conveyance system mainly functions as conveying the pulverized coal into the finished product tank and long-distance conveyance is available.

Intelligent Central Control System

With the industrial computer as the core unit of the entire system, the central control system reads the PLC or ECS by multiple communication technologies to collect the conditions of the site equipment and, based on the conditions of site equipment, computer sends commands to control the site equipment to realize the functions, including remote control of equipment, record analysis of equipment information, and printed equipment running report.

The MTW European Grinder has the expert intelligent control system developed and designed especially for pulverized coal grinders and adopts the ESC intelligent control system to realize the centralized control and the remote monitoring function---observing the production line running conditions via mobile terminal equipment such as mobile phone and iPad, can also be realized.

Process Analysis

The raw coal in the raw coal bin is fed by constant volume belt feeder into the scraper conveyor by which the raw coal is then sent into the dryer for baking. After baking, the raw coal is conveyed by the enclosed scraper conveyor to the enclosed storage bin. Transferred by truck to the raw material bin of pulverization system, the raw coal then is fed by speed regulation belt conveyor into the MTW215 European Grinder. The pulverized coal, graded by the pulverized coal separator, is supplied along the pipeline into the pulverized coal collector (The residual gas is collected by pulse dust collector). The finished pulverized coal collected is fed by screw conveyance system into the pulverized coal elevator to finished pulverized coal bin for storage. The pulverized coal is transported by the tanker truck depending on the actual needs. The entire system is fitted with nitrogen generator system and CO2 system for explosion-proof and fire-extinguishing protections and its critical parts are installed with explosion-proof valve to guard equipment against damage.

Project Advantages

Project General Contracting Service

To minimize the project construction period and reduce the customer’s investment, this pulverized coal preparation project adopts the project general contracting service. The project general contracting service is a “turnkey” service project designed by ZENITH especially for the customer’s production convenience needs. This service runs through all projects steps, including site terrain environment survey and investigation, production line process design, raw material inspection and testing, finished product requirement analysis, customer investment cost budget, and equipment installation and commissioning, which can prevent the interruption of operation and delay of production due to customer’s special causes such as inadequate preparation of construction materials and labor shortage. The project general contracting service realized the maximum production convenience for the customer, met the customer’s need of urgent production schedule, and won the high appraisal from the Shandong customer.

Operation Convenience

To promote the operation convenience of pulverized coal production line, this production line adopts the unique two-step (baking and pulverizing) operation method. The two-step pulverized coal preparation system is a solution with baking and pulverizing separated. With relatively low grinding chamber temperature, it’s the unique pulverized coal production process of MTW European Grinder. This process system features relative simple and easy control and can remarkably improve the safety performance of the production line.

1. Raw coal bin 2. Dryer 3. Weighing coal feeder 4. MTW European Grinder 5. Pulse dust collector 6. Pulverized coal collector 7. Fan 8. Finished coal bin 9. Pulverized coal bin 10. Monitoring system 11. Explosion-proof system 12. Central control system

Low Investment

The MTW series European Grinder adopts multiple advanced technologies, including integral bevel gear drive, internal thin oil lubrication system, and oil temperature online measurement, and boasts multiple proprietary patented technological property rights, characterized by small occupation area, low comprehensive investment, low operating cost, high efficiency, and environmental protection.

High Safety and Environmental-Friendliness

To guarantee the fire-proof and explosion-proof safety performance during the pulverized coal production, the production line is fitted with nitrogen system, CO, and CO2 fire extinguishing system to guarantee running safety and stability of equipment to the maximum extent.

Meanwhile, the effective measures are taken to strictly control the dust concentration of exhaust gas within the national specified range. The production line adopts the pulse dust collector manufactured with advanced technologies to reduce the influence on the surrounding environment to the maximum extent.

Evaluation of Benefits

Evaluation of Economic Benefit

A coal-fired boiler reformed by pulverized coal atomization technology can promote the combustion efficiency to 98%, the thermal efficiency to >90%, and steam output per ton from 5.5T to >9T. Compared with a traditional coal-fired boiler, it can save coal by >30%, electricity by 20%, water by 10%, land by 60%, and manpower by 50%. The pulverized coal produced realized the sales volume of RMB 800 million and the profit and tax of RMB 100 million.

Evaluation of Social Benefit

The pulverized coal produced by this production line is supplied via pulverized coal atomization technology to the industrial boiler for combustion, which breaks the traditional block coal combustion status and is an example of high-efficiency and clean coal utilization that boosts the transformation and upgrade of coal industry. It’s of enlightening significance for the coal enterprise to successfully live through this severe situation.

Evaluation of Environmental Benefit

All atmospheric pollution emission indicators meet the emission standard of a natural gas boiler to eliminate the dust, coal, slag, and smoke.

Customer Feedback

Due to large scale of this pulverized coal production line and high quality requirement on pulverized coal, through extremely careful selection of manufacturers and the long-time multi-aspects investigation, we finally selected the equipment manufactured by ZENITH. From the site investigation to the installation and commissioning, we received professional solutions and services and four coal pulverization grinders (Phase-II) are running well, with the production capacity exceeding the design capacity.

Extended Reading

Pulverized Coal Atomization Technology

The core of this technology is the “pulverized coal configuration and multiple vortex atomization”, namely the high speed air vortex is mixed with grained coal of 200 mesh into the vortex atomizer so that the pulverized coal and the air are sufficiently mixed and atomized to form a vortex and are fed into the boiler for floating combustion to realize high-efficiency combustion via thermodynamic system, measurement and control system, and exhaust gas purification system, with the emission meeting the standard same as that of natural gas.

The pulverized coal used in the high-efficiency pulverized coal boiler system is selected, dried, and ground to pulverized coal of 200 mesh for centralized management and distribution, which can effectively guarantee the quality stability of pulverized coal and eliminate the scattered coal piles and reduce the ground pollution, featuring high efficiency and energy conservation, clean emission, high automation level, environmental-friendliness, and outstanding economic, environmental, and energy conservancy benefits. The vigorous development, promotion, and application of high-efficiency and environmental-friendly pulverized coal boilers is of important significance to boost the clean and efficient coal utilization, improve the atmospheric environment, and develop the energy conservation and environment protection industry.