https://cementl.com/ The bowl mill consists of a rotating bowl supported on a gearbox assembly. Three or more grinding rollers press against the surface of the bowl, crushing the coal that is fed from the center. The grinding pressure is provided by heavy coil springs or, in more modern designs, by hydraulic cylinders. In a hydraulic spring system, the pressure can be adjusted precisely according to coal hardness and boiler load, maintaining stable grinding force even as the rollers and segments wear.
Website: https://cementl.com/
Email: [email protected]
Whatsapp: +86 15988878668
Raw coal, usually sized below 40–50 mm, enters the mill through a central feed pipe. As the bowl rotates at about 30–40 rpm, centrifugal force moves the coal outward, where it is trapped between the bowl surface and grinding rollers. The applied spring or hydraulic pressure (typically 60–90 kN per roller) crushes the coal into smaller particles. Primary hot air, supplied from the boiler air preheater at 250–300°C, enters the mill to dry the coal and carry the fine powder upward.
The separator, located above the grinding zone, classifies the material. Coarse particles fall back onto the bowl for further grinding, while fine particles are carried with the air stream toward the furnace burners. For conventional boilers, the pulverized fuel must reach a fineness where 70–75% passes through 200 mesh (75 μm). In advanced supercritical boilers, even finer grinding is targeted, up to 80–85% passing 200 mesh, to improve combustion and efficiency.
A typical hydraulic spring loaded bowl mill for a 500 MW unit processes 35–55 tons of coal per hour, depending on coal quality. For larger 800–1000 MW plants, individual mills may handle 60–80 tons per hour. Mill motor ratings are usually 600–1000 kW, driving the bowl via a worm gear or planetary gearbox. The outlet temperature of the pulverized fuel-air mixture is controlled between 65–80°C to prevent moisture condensation and minimize fire risk in the coal pipes.
Maintenance and wear management are important in bowl mill operation. The grinding rolls and bowl segments are subject to abrasion from mineral impurities. Periodic hardfacing or replacement is required to maintain performance. The hydraulic spring loading system helps compensate for wear by maintaining constant grinding force. Rejects such as pyrites, tramp iron, and stones are discharged into a pyrite hopper located below the grinding zone.
Safe operation requires continuous monitoring. Mill differential pressure (typically 6–12 inches w.g.) indicates coal bed buildup. Excessive vibration may signal roller imbalance or spring system malfunction. CO monitoring and inerting systems using N₂ or CO₂ are employed to prevent fire or explosion during startup, shutdown, or upset conditions.
The bowl mill design is versatile, allowing operation with different solid fuels. While bituminous coal remains the most common, many plants also use blends with lignite, petroleum coke, or biomass. Adjustments to grinding pressure, classifier speed, and hot air temperature allow the mill to adapt to these varying fuels. This flexibility supports utilities in regions where coal quality changes frequently.
In thermal power plant operation, the performance of the pulverizer directly affects boiler efficiency, furnace flame stability, and emissions. A well-maintained hydraulic spring loaded bowl mill ensures uniform fuel fineness, stable flame temperature (around 1700–1800°C in the furnace), and reduced unburnt carbon in fly ash.
In summary, the hydraulic spring loaded vertical bowl mill pulverizer remains a cornerstone of solid fuel preparation in power generation. Its design combines crushing, drying, and classification in a compact machine, with hydraulic or spring force ensuring consistent grinding pressure. Proper operation and wear management enable reliable boiler performance, efficient combustion, and long equipment life in large thermal power plants.
#vrm #verticalrollermill #cement #cementindustry #ballmill #ballmillfactory #ballmillparts #dryer #granulator #cooler #machinery #heavymachinery #mining #cement #crusher #ballmill #rotarykiln #agriculture #agricultureequipment #verticalrollermill #clinkergrindingunit #cementequipment #ballmill #ballmillsupplier #cementplant #rotarykiln #rotarykilnparts #kiln #shaftkiln #mining #cement #crusher #rotarydryer #girthgear #casting #metalcasting #foundry #supportroller #ridingring #tyre #edgedrive #centraldrive #cementmachine #cement #cementcrushing #cementplant #cementballs #ballmillparts #ballmillfactory #cementgrindingplant #clinkergrinding #rotarykilnparts #grinding #grindingplant #grindingequipment #tongli #zhejiangtongli #tongliheavymachinery #Rollpress #Impactcrusher #Impactor #tonglicement #JawCrusher #angola #tanzania #namibia #ghana #kenya #zimbabwe #nigeria
Информация по комментариям в разработке