What is rotary dryer?
, also known as rotary drum dryer
, is a kind of drying equipment, which is widely used in mining equipment
. Rotary vacuum dryer
is suitable for drying magnetic, heavy and floating concentrates of metal and non-metal ores and clay of cement industry and coal slurry of coal mining industry. Rotary drum dryer
are characterized by high productivity and convenient operation. The barrel of industrial rotary dryer
is a horizontal rotary cylinder, and there are various kinds of coping plates with different angles welded from front to back, and different types of refractory bricks are set inside the rotary kiln according to the demand, and there are door rings and spiral coping plates at the feeding end to prevent the material from falling.
Working principle of rotary dryer
The dry wet material is delivered to the hopper by belt conveyor or bucket elevator. Then it enters the charging end through the charging pipe via the charging machine of the hopper. The slope of the charging tube is greater than the natural inclination of the material so that the material flows smoothly into the dryer. The dryer cylinder of rotary dryer machine is a rotating cylinder which is slightly inclined to the horizontal line. The material is added from the higher end, and the heat carrier enters from the lower end and makes counter-current contact with the material, and there is also a parallel flow of the heat carrier and material into the cylinder. With the rotation of the cylinder material by gravity to the bottom end of the run. Wet materials in the cylinder body moving forward in the process, directly or indirectly by the heat carrier to heat, so that wet materials can be dried, and then in the discharge end by the belt or screw conveyor sent out. The inner wall of the cylinder is equipped with a copying plate, whose function is to copy up and scatter the materials, so that the contact surface between the materials and the airflow increases, in order to improve the drying rate and promote the advancement of materials. The heat carrier is generally divided into hot air, flue gas and so on. After the heat carrier through the dryer, generally need the cyclone dust collector will be carried in the gas material trapped down. To further reduce the dust content of the exhaust gas, it should also be put through the bag filter or wet dust collector before discharge.
Working process of rotary dryer
The drying medium of direct heat transfer rotary dryer is usually flue gas. Direct heat transfer rotary dryer of downstream type, its combustion chamber is at the same end with wet material feeding, the direction of movement of hot air flow and material is the same, wet material moves from feeding end to discharging end, hot air also flows out from feeding end by discharging end under the action of blower and induced fan, wet material is heated by hot air and dried in this flowing process.
Counter-flow direct heat transfer rotary dryer, it is wet materials from the feed end into the dryer, the combustion chamber is located in the discharge end, materials and drying medium (hot air) for the opposite direction of movement, materials in the process of heating and drying.
Downstream drying because of the wet materials fed into the dryer into contact with the higher temperature of the drying medium, the initial drying propulsion is larger, and later with the rise in material temperature, the temperature of the drying medium is reduced. Therefore, it is suitable for materials with low requirements on final moisture content (i.e. drying degree). The temperature of the discharged dry material is low, which is easy to transport. However, from the point of view of dust generation, fine materials are easily carried away by the airflow, and the amount of dust is larger. Countercurrent drying in the drying process, drying propulsion uniform, suitable for the dried materials require more stringent drying. The dust carried by the drying medium is filtered out by the wet material area, and the dust content in the airflow is less. The specific choice of drying depends on the final requirements of the materials to be dried.
Type of rotary dryer
According to the way of heat transfer between drying medium and wet material, rotary dryer is divided into two kinds: direct heat transfer rotary dryer and indirect rotary dryer.
The indirect heat transfer rotary dryer is rarely used for reasons such as low transfer efficiency and complicated structure.
Direct heat transfer rotary dryer
According to the direction of drying medium and material flow, the direct heat transfer rotary dryer is divided into two kinds: downstream and counterflow.
The main part of the rotary steam tube dryer is a rotating cylinder which is slightly inclined to the horizontal line. The cylinder is driven by gears, and the rotational speed is generally 2~6r/min. The inclination of the cylinder is related to its length, usually between 1°~5°. The material is fed from the higher section of the rotating cylinder and comes into contact with the hot air. With the rotation of the cylinder, the material flows to the lower end under the action of gravity and is dried and discharged. As the dryer works under negative pressure, the feeding and discharging ends are sealed to avoid air leakage.
Feature of rotary dryer
a. The drum dryer machine designed and produced with multi-combination lifting device has made various technical innovations on the lifting device system, and adopted a new multi-combination lifting device. This device, with high thermal efficiency and coal consumption reduced by about 20%, overcomes the phenomenon of "wind tunnel" of traditional dryer.
b. Suitable for a variety of combustion furnaces, such as high-temperature boiling furnace, grinding coal injection furnace and artificial coal furnace, etc.
c. The transmission size gear adopts pin column interchangeable gear, replacing the traditional cast steel gear, saving cost investment and greatly reducing maintenance cost and time.
d. With centralized control system, it can realize central monitoring and management of microcomputer in large enterprises.
e. Larger production capacity, continuous operation.
f. Simple structure, easy to operate.
g. Fault less, low maintenance cost.
h. Wide range of application, it can be used to dry granular materials, and it is also beneficial for those materials with large adhesion.
i. Wide range of application, it can be used to dry granular materials, and it is also beneficial for those materials with large adhesion.
j. Easy to clean.
Application of rotary dryer
Rotary dryer is mainly used for drying granules and powders in chemical, metallurgical, building materials, mining and other industries.
Use of rotary dryer
a. Installed dryer should be no less than 4 hours of empty machine test run, test run work occurs in abnormal conditions should be dealt with in a timely manner.
b. After the end of the test run again tighten all the connecting bolts, check and make up sufficient lubricating oil, and after the normal test rotation, you can carry out a load test run.
c. Before the load test run, the auxiliary equipment should be tested in stand-alone operation. After the successful single machine test run, it will be transferred to the joint test run.
d. Ignite the hot air furnace dryer preheat, and turn on the dryer at the same time, prohibit the cylinder does not turn heating to prevent the cylinder from bending.
e. According to the preheating situation, gradually add wet materials to the drying cylinder, and gradually increase the feeding amount according to the moisture content of the discharged materials. Dryer preheating needs a process, hot air furnace should also have a preheating process, prohibit the sudden big fire burning. Prevent local overheating, thermal expansion unevenly and cause damage.
f. The high and low fuel combustion value, the quality of insulation of each part, the amount of moisture contained in the wet material, and the uniformity of feeding quantity affect the quality of drying products and the consumption of fuel. So making each part reach the best state as possible is an effective way to improve economic efficiency.
g. In the working state, the pallet rack should be filled with cooling water. Each lubrication part should be refueled in time.
h. When stopping, the hot air furnace should be turned off first, and the drying cylinder should continue to rotate until it cools down to near outside temperature before stopping. Prohibit high temperature parking to prevent the cylinder from bending and deformation.
i. When encountering a sudden power failure, the hot air furnace should be immediately turned off, stop feeding, every 15 minutes pan rotating cylinder half a turn until the cylinder cools. This operation procedure should be seriously responsible, violating this procedure will cause the cylinder body bending. Severe bending of the cylinder will make the dryer unable to use normally.
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