The low efficiency of quartz sand drying equipment is not caused by a single
factor, which is mainly related to heat source supply, equipment parameters,
material characteristics and equipment maintenance, and each dimension has
specific causes.
1、 Heat supply problem: insufficient heat or poor heat
Heat source is the core power of drying. Insufficient heat or low utilization
efficiency will directly reduce the drying efficiency.
Low or unstable heat source temperature: for example, the nozzle of the
natural gas burner is blocked, the air valve is improperly adjusted, the fuel
cannot be fully burned, and the hot air temperature cannot reach the design
value (for example, the rated temperature is 600-800 ℃, and the actual
temperature is only 400 ℃); Due to poor coal quality, insufficient air supply,
increasing and decreasing flame and large fluctuation in heat output of
coal-fired hot-blast furnace.
Uneven distribution of hot air: the design of hot air inlet is not
reasonable, and it is only concentrated on one end of the roller and cannot be
uniformly diffused to the whole roller; The internal plate of the roller is worn
and deformed, which cannot fully lift the materials, resulting in insufficient
heating of materials in some areas and waste of heat due to overheating in some
areas.
Excessive heat loss: the hot air pipe and roller shell are not insulated or
the insulation layer is aged and damaged, the heat is lost through the outer
wall, and the temperature of the outer wall of the pipe is over 60 ℃ when
touched by hand, and a large amount of heat is wasted without acting on the
material.
2、 Poor adaptability of equipment parameters: "wrong tempo" slowing down
efficiency
The parameters such as rotating speed, inclination and feeding amount of the
equipment are not matched with the characteristics of quartz sand, which will
lead to "wrong waiting" and "unsmooth running" of the materials in the
roller.
Improper rotating speed of roller: when the rotating speed is too fast, the
materials stay in the roller for too short time (less than 5 minutes), and the
materials are discharged when the contact with hot air is not sufficient; If the
rotating speed is too slow, the materials will accumulate at the bottom of the
roller, which is easy to adhere to the wall of the roller to form a "pasting
cylinder". It will not only dry slowly, but also block the equipment.
Unreasonable inclination of roller: excessive inclination (more than 5 °),
fast sliding speed of materials, short retention time and incomplete drying; If
the dip angle is too small (less than 2 °), the material flow is slow, or even
the material is "inverted" (unable to move to the outlet), and the capacity
drops suddenly.
Overload or uneven feeding capacity: if the feeding capacity exceeds the
rated capacity of the equipment (such as rated 20t/h, actual feeding 25t/h), the
materials in the roller are piled too thick, and the hot air cannot penetrate
the material layer; The feeding fluctuates from time to time, resulting in
material fluctuation in the roller, disordered drying pace and unstable
efficiency.
3、 Mismatching of material characteristics: the "natural conditions" of raw
materials drag the back
The moisture content, particle size and impurity content of quartz sand will
directly affect the drying difficulty and efficiency.
The initial moisture content is too high: for example, the moisture content
of quartz sand after ore washing exceeds 20%, it is easy to agglomerate after
entering the dryer, block the roller plate, the hot air cannot fully contact
with the materials, and there is still a "wet mass" after drying, and it needs a
longer time to dry.
Too large particle size difference: coarse particles (>2mm) and fine
particles (<0.1mm) are mixed, and fine particles are easily taken away by hot
air to cause waste, and too fast drying is easy to overheat; Small heating area
of coarse particles, slow drying and low overall efficiency.
Too much impurity content: the materials contain clay, organic matter and
other impurities. During drying, the impurities stick to the roller wall and the
plate to form a "scaling layer", which hinders the heat transfer. Frequent
shutdown cleaning is required to further reduce the efficiency.
4、 Improper equipment maintenance and operation: "day after day management"
is not in place
Wear of equipment parts and non-standard operation will gradually reduce
equipment performance and efficiency.
Wearing or blocking of equipment parts: the inner plate of the roller is worn
or broken, and the materials cannot be lifted; The sealing elements at the
feeding end are aged and damaged, the cold air penetrates and the hot air leaks,
resulting in the temperature drop in the roller; The filter bag of the dust
collector is blocked, the air exhaust is not smooth, the negative pressure in
the roller is insufficient, and the hot air cannot flow smoothly.
The operator's operation is not standard: the parameters are not adjusted
according to the regulations (such as changing the hot air temperature and
rotating speed at will); Equipment blockage is not cleared timely (such as
caking of plate and blockage of dust collector); The production data is not
recorded, the cause of the problem cannot be traced, and the efficiency problem
cannot be solved for a long time.