The drum dryer is the core equipment for quartz sand dewatering, responsible
for drying sand particles with a moisture content of 15% -20% after washing to
below 5% (industrial grade standard). If the drying efficiency is low (the unit
time output is less than 60% of the rated value) and the moisture content of the
finished product exceeds the standard (more than 8%), it will lead to subsequent
screening blockage and product storage agglomeration. Based on practical
experience, summarize a three-step troubleshooting method to quickly restore
drying performance.
Step 1: Overhaul the heating system and temperature control - heat source
stability is the foundation
Insufficient heat supply or temperature fluctuations are the core reasons for
slow drying.
Burner malfunction or heat loss: Gas burner nozzle blockage (carbon
deposition thickness exceeding 2mm), resulting in a decrease of more than 30% in
heat output; Improper air distribution and insufficient combustion in coal-fired
boilers result in flue gas temperatures below 600 ℃. Clean the burner nozzle
(blow with a high-pressure air gun at 0.6MPa), adjust the air door opening to
30% -40%, and ensure that the flue gas temperature is stable at 700-800 ℃;
Install a 50mm rock wool insulation layer on the dryer cylinder to reduce heat
loss, and control the surface temperature of the cylinder below 60 ℃.
Temperature sensor distortion or control lag: Sensor measurement deviation
exceeds ± 20 ℃, leading to misjudgment of heat source supply; The response time
of the temperature control system exceeds 10 seconds, and the firepower cannot
be adjusted in a timely manner. Replace the PT100 high-precision sensor (error
≤± 5 ℃) and calibrate the temperature control instrument; Activate the "PID
automatic adjustment" function to control the temperature fluctuation range
within ± 15 ℃, ensuring that the heat source accurately matches the drying
requirements.
Step 2: Check the drum structure and speed - even rolling of materials is
key
Abnormal internal structure and rotational speed of the drum can lead to
uneven heating.
Wear or unreasonable arrangement of the cutting board: The cutting board wear
exceeds 1/3 of the original height, unable to effectively roll the animal
material, and the bottom material accumulates for a long time, resulting in
incomplete drying; The arrangement of copied boards is sparse (with a spacing of
over 200mm), and the material dispersion is poor. Replace the high chromium
alloy plate and arrange it in a "spiral staggered pattern" (with a spacing of
150mm) to ensure that the material forms a uniform material curtain inside the
drum; Install a dispersing device at the feeding end of the drum to remove
clumped sand particles (particle size exceeding 50mm) and increase the heating
surface area.
The drum speed is too fast or too slow: the speed exceeds 4 r/min, the
material residence time is less than 15 minutes, and the moisture is not fully
evaporated; Below 2r/min, the material accumulation is too thick, and the hot
air flow cannot penetrate. Use a tachometer to detect and adjust to 2.5-3 r/min,
and achieve stepless speed regulation through a frequency converter; Dynamically
adjust according to the initial moisture content of the material. When the
moisture content exceeds 18%, reduce the speed appropriately (2.5r/min) and
extend the drying time.
Step 3: Optimize airflow circulation and feed parameters - gas-solid
adaptation to improve efficiency
Improper adaptation of airflow speed, feed rate, and materials can exacerbate
drying problems.
Insufficient air volume or short circuit of induced draft fan: The air volume
is below 70% of the rated value of the equipment, and the humid and hot gases
cannot be discharged in a timely manner; The deformation of the windshield
caused the hot air flow to directly pass through the drum, without sufficient
heat exchange with the material. Replace the high-power induced draft fan
(ensuring a wind speed of 1.2-1.5m/s) and clean the dust accumulation in the air
duct; Calibrate the angle of the windshield to 45 °, install a deflector, force
the airflow to come into reverse contact with the material, and improve heat
exchange efficiency.
Overloading of feed volume or uneven moisture content: exceeding the rated
processing capacity (such as 30t/h, actual 40t/h), material accumulation in the
drum exceeds one-third of the drum volume; The fluctuation of moisture content
in raw materials exceeds 5%, resulting in unstable drying effect. Use an
electronic belt scale to control the amount and maintain it at 80% -90% of the
rated value. Install a pre dehydration process (such as a dehydration screen) to
reduce the initial moisture content to below 12%; Install a moisture online
detector at the feed inlet, provide real-time feedback data, and adjust the heat
source and speed in conjunction.
Daily maintenance should pay attention to: cleaning the carbon deposits on
the burner and checking the operation status of the induced draft fan every day;
Calibrate the temperature sensor and tighten the drum support wheel bolts every
week; Check the wear of the copying board every month and clean the materials
adhered to the inner wall of the drum (when the thickness exceeds 10mm). By
taking the above measures, the drying efficiency can be improved by more than
30%, and the moisture content of the finished product can be stabilized at 3%
-5%, ensuring the continuous operation of the quartz sand production line. If
there are still problems, it is recommended to contact the manufacturer to test
the compatibility between the heat load and the material, and optimize the
drying process parameters.