The size of the machines keeps growing too. Although some prep plant operators have adopted wider screens, others are reluctant to dive right in. New U.S. plants are being built as a single-line process and wider screens are probably the easiest way to improve throughput in that type of system. Apart from capacity, the bigger machines also lessen the screening footprint within the plant? One large screen instead of multiple smaller screens.
Coal vibrating screen serves several functions within the modern prep plant. First of all is size separation, but they also dewater and take away impurities. The U.S. coal industry varies by region and thus does screening needs. Not only may be the hardness of the coal an issue, but other conditions for example rock, clay and acidic water affect a screen?
Vibrating Screen and the general screening of different classification, which uses circular vibration, so the screen changes at the crude steel produced the phenomenon of false, thereby helping the probability of the role of screening, you can use a larger mesh, more productive. Since only single-axis circular shaker excitation, therefore the structure more simple, noise and vibration of small easy maintenance, durable. Shaker is specifically designed for the quarry screening material stone, but also for types of coal mining, coal preparation, mineral processing, building materials, electricity and chemical industries etc.
Coal is first crushed by coal preparation machinery to some size of 20 to 25 mm and it is then fed to coal bunkers. Coal feeders feed this crushed coal continuously to coal mill according to requirement. Coal gets ground by grinding elements in stages. Coal particles get re-circulated around 4 times before achieving required fineness. Classifier allows finer particles to escape mill outlet while coarse particles are returned to mill for further grinding. Primary air comes by P.A. fan through air pre heaters to coal mill or in some boilers, P.A. fan pressurize heat received from air pre heaters and then supply to mills. Hot primary air drives moisture from coal and acts as carrier to move pulverized coal to the boiler through pipes.
Output is pulverized coal having required fineness. For complete combustion coal must have fineness of 75% through 200 mesh and 99.5% through 50 meshes. Primary air + coal mixture flowing through each coal pipes should have minimum velocity of 18 m/sec, Temp. Around 80 degrees C, and air/coal ratio of 1.8 -2. Fuel flow through pipes is balanced within range of +/-10%. Finer is the coal, better may be the flow distribution.data mining Photo
By GDJ from Pixabay