After running the three return drum dryer for one or two years, many
customers have found that the drying effect has significantly decreased -
despite the same hot air temperature, the moisture content of the discharged
material is higher than before, and there are often "wet lumps" at the tail of
the drum that have not been dried. The heat source and speed are both normal,
but the problem often lies in the reading board.
If the wear and tear of the copied board exceeds one-third of the original
height, the material cannot be lifted up. The function of copying board is to
sprinkle quartz sand belt to a certain height, forming a material curtain and
fully contacting with hot air. After becoming thinner and shorter due to wear
and tear, the material carrying capacity of the copied board decreases, and a
large amount of wet sand accumulates at the bottom of the cylinder to form a
"dead material zone", greatly reducing the heating area. The judgment method is
simple: after stopping the machine, enter through the manhole door and measure
the height of the board with a tape measure. If the wear exceeds one-third, it
should be replaced.
The spacing between the copied boards is too large, and the material curtain
is not fully covered. The normal spacing should be controlled between 150-200mm.
When the spacing is too large, no material is lifted in the area between the
copied boards, and hot air passes directly through the gaps, resulting in a
significant decrease in thermal efficiency. During inspection, measure along the
axial direction of the cylinder section by section. If uneven spacing or
exceeding 200mm is found, it is necessary to weld and install new cutting plates
or adjust the original cutting plate position.
Choosing the wrong material for copying the board will accelerate the wear
rate exponentially. Ordinary carbon steel sheets will be worn off in three to
five months under the erosion of quartz sand. It is recommended to use
wear-resistant steel (such as NM400) to make the sheet, which has a wear
resistance more than three times higher than ordinary carbon steel. During
installation, the bolts must be tightened to prevent loosening and detachment
caused by vibration during operation. After replacing the copying board, run it
without load for half an hour to confirm that there is no looseness before
feeding.
Pay attention to observing whether there are "wet lumps" or unevenly dried
materials at the discharge end during daily inspections. If the temperature of
the heat source is normal but the drying effect continues to decrease, first
check the wear of the board. Shanlu Heavy Industry has accumulated many years of
experience in the field of quartz sand drying equipment and can provide
customized and replacement suggestions for cutting plates according to the
specifications of the cylinder. Encountering problems during equipment
operation, welcome to contact the technical team of Shandong Heavy Industry for
communication: Manager Zhang 13583776655 (same as WeChat).