Hollow Paddle Dryer Overview
在设备内部设置搅拌浆叶，使湿物料在桨叶的搅动下，与热载体以及热表面充分接触，从而达到干燥目的的低速搅拌干燥机。 Hollow paddle dryer is a low-speed stirring dryer equipped with stirring blades inside the equipment to make wet materials fully contact the heat carrier and the hot surface under the stirring of the paddles. 、 盘式干燥机一样，都属于热传导型干燥设备。 Hollow blade dryers, like target dryers and disc dryers , are heat-conducting dryers.
The hollow blade dryer is mainly composed of two or four hollow blade shafts meshing with each other, a W-shaped jacket housing, a transmission part and a machine base. The structure is generally horizontal. Hollow shafts are densely arranged with wedge-shaped hollow paddle blades. The heating medium is usually steam, hot water or thermal oil. When working, the heating medium is divided into two paths, which enter the jacket shell and the inner cavity of the propeller shaft, respectively, and simultaneously heat the dryer body and the propeller shaft. Among them, the shaft end of the hollow blade dryer is equipped with a rotary joint, and the heating medium flows through the hollow shaft and the hollow pulp blade through the rotary joint to import and export. The hollow shaft and the hollow pulp blade have different internal structures according to the type of heating medium To ensure better heat transfer effect. The jacket housing has a sealed end cover and an upper cover to prevent leakage of material dust and collection of solvent vapors of the material. A baffle is arranged at the discharge port to ensure the height of the material level, so that the heat transfer surface is covered by the material and fully exerts the heating effect.
Hollow paddle dryer is a horizontal stirring dryer with heat conduction as the main part. Because the hollow stirring blade is shaped like a ship's paddle, it is called a hollow paddle dryer. The hollow paddle dryer was successfully developed by Germany as the earliest. Later, Japan introduced the technology and improved it, and developed a series of more than ten specifications with two and four shaft structures. Since the heat required by the equipment for drying is indirectly heated by heat conduction, only a small amount of gas is needed to remove the moisture during the drying process, which greatly reduces the loss of heat taken away by the gas and improves the use of heat. rate. Hollow paddle dryer is an energy-saving drying equipment, which is suitable for drying granular and powder materials, and can also dry paste materials smoothly.
Hollow paddle dryer picture
Working principle of hollow blade dryer
Hollow paddle dryers mainly heat and dry materials by conduction heating. The main structure is a pair of hollow low-speed rotating hollow shafts in a W-shaped housing with a jacket. Several hollow stirring blades are welded on the shaft. The jacket and the hollow stirring blades are connected with a heat carrier. Both heating surfaces are simultaneously Heat the material. Wedge-shaped hollow paddle blades are densely arranged on the hollow shaft, and the heat medium flows through the hollow shaft through the paddle blades, and the heat transfer area in a unit effective volume is large. The temperature of the heat medium is generally from 80 to 250 ° C. It can be water vapor, hot water, thermal oil, etc. The dried material is continuously and quantitatively fed into the dryer's feeding port by the screw feeder. After the material enters the body, the material is turned and stirred by the rotation of the paddle, and the heating interface is continuously updated, and it is in contact with the body and the blade, It is fully heated to evaporate the surface moisture contained in the material. At the same time, the material is conveyed in the spiral trajectory with the rotation of the paddle shaft toward the discharge port, and the stirring is continued during the transportation, so that the water seepage in the material continues to evaporate. The dry and qualified products are discharged from the discharge port.
The entire drying process is mainly indirect conduction heating. Most of the heat is used to heat the materials. The heat loss is only a small amount of air that is passed in to take away the moisture, and the heat is radiated to the environment through the thermal insulation layer of the device. The wedge-shaped blade heat transfer surface has a self-cleaning function. The relative movement of the material particles and the wedge-shaped surface produces a scrubbing effect, which can scrub away the attached materials on the wedge-shaped surface, so that the clean heat-transfer surface is always maintained during the movement. The entire drying process of the material is carried out in a closed and slightly negative pressure state. Organic volatiles, odorous gases and moisture are sent to the exhaust gas treatment unit through the air induction device, thereby avoiding environmental pollution.
Characteristics of the use of hollow paddle dryer
● The hollow blade dryer has a compact structure and a small footprint
The heat required by the dryer is mainly provided by the hollow paddle wall surface arranged on the blade shaft. These paddle blades are densely arranged at a certain interval on a fixed rotating shaft, and the heat transfer on the jacket wall surface only accounts for a small part . Therefore, the heat transfer area per unit volume of equipment is large, which can save equipment footprint and reduce infrastructure investment.
热量利用率高 ● High heat utilization
Using conduction heating, all heat transfer surfaces are covered by materials, reducing heat loss. At the same time, because the materials are continuously mixed and stirred well, the surface of the relatively rotating paddle blades and the heating of the jacket ensure that all surfaces in contact with the product can evenly transfer heat energy.
● Wedge-shaped blades have self-cleaning ability
The dispersive force generated by the combined movement of the inclined surface of the rotary blade and the material particles automatically removes the material particles attached to the heating inclined surface, prevents material adhesion, improves heat transfer efficiency and prevents material sintering. In addition, the two-axis blades rotate in reverse, alternately compressing in stages (when the two-axis blades are closest to each other) and expanding (when the two-axis blades are farthest from each other), the stirring function, uniform heat transfer, and improve Heat transfer effect.
尾气量少 ● Less exhaust
Since no gas is needed for heating, only a small amount of gas is needed to carry away the moisture, and the dust entrained by the gas is also small. Therefore, the scale of the post-stage dust removal and exhaust gas treatment devices can be reduced, saving environmental protection equipment investment.
● Simple control and wide adaptability to material moisture content
Both the drying process and the dwell time can be easily checked, controlled and adjusted. They can be individually set and adjusted according to the physical properties of the product being dried, such as feeding speed, shaft speed and heat carrier temperature, etc., so the adaptability to changes in the moisture content of the material is very wide.
出料调节机构，方便调节物料终水份含量，增加空心桨叶烘干机操作弹性。 ● The discharge adjustment mechanism is convenient to adjust the final moisture content of the material and increase the operating flexibility of the hollow paddle dryer.
An overflow weir is set in the hollow paddle dryer, which can adjust the residence time of the material in the hollow paddle dryer according to the nature of the material to meet the requirements for the change of the moisture content of the material.
特殊的冷凝水排出结构，及时排出蒸汽冷凝水与不凝气体，保持较高传热效率。 ● Special condensate drainage structure, timely discharge steam condensate and non-condensable gas, maintain high heat transfer efficiency.
设计腐蚀裕量与磨损裕量，保证空心桨叶烘干机使用寿命。 ● Design of corrosion allowance and wear allowance to ensure the life of the hollow blade dryer.
The speed of the blades is very low, usually only 2-15 revolutions per minute, which effectively reduces wear. At the same time, in the design, we will choose the appropriate material according to the nature of the material, and consider the certain corrosion allowance and wear allowance when calculating the material wall thickness.
Manufacturing process of hollow paddle dryer
CNC cutting and blanking to ensure the accuracy of component group alignment;
Scientific and reasonable welding process specification WPS and manufacturing process control to ensure welding quality;
The blade shaft is processed integrally after welding to ensure the running accuracy;
Nondestructive testing of welds according to pressure vessel manufacturing standards;
Carry out pressure and leak tests according to pressure vessel manufacturing standards;
Final assembly of equipment and test run;
Sand blasting, derusting and painting of equipment;
Process chart of hollow paddle dryer
1. Normal pressure drying process
The material is added from the feeding port, and moves to the discharging port under the action of the spiral blades rotating opposite to each other. The steam transfers heat to the material through the spiral wedge blades and jackets, and the evaporated moisture is emptied by the dust collector and exhaust fan. Due to the small amount of air required for conductive drying, the outlet wind speed is generally low and the dust entrainment is lighter, but the humidity is generally high. The dew point of moisture must be considered to prevent condensation in the discharge circuit. To this end, the general supplementary air requires It can only be introduced into the dryer after heating. Vapor and condensed water are introduced and discharged through the rotary joint.
2. Atmospheric pressure return material drying process
Generally speaking, the paddle dryer can directly process high water-containing or viscous materials, but when some materials are too high or very viscous, the heating surface refresh rate of the wedge-shaped blades and jackets decreases, and the heat transfer coefficient decreases. Atmospheric pressure re-drying process can be used to return part of the dry material, so that the moisture content of the material fed to the dryer is controlled to a certain level and a high heat transfer rate is maintained. The other parts of the process are the same as the normal pressure drying process.
3. Solvent recovery type drying process
The system is fully enclosed and operates under vacuum. No additional air is required. The evaporated solvent is removed by the dust collector and the solvent is recovered by the condenser. The non-condensable gas is evacuated by the vacuum pump. The vapour flow is the same as the normal pressure type. The feeding and discharging of materials requires special systems to isolate the system from the atmosphere. This process is suitable for materials that require solvent recovery, but also for materials that do not recover solvent but need to be dried under vacuum. At this time, the solvent recovery tank is changed to a soda-water separator. As a special case, this process can also be used to evaporate volatiles from high-boiling, viscous materials that are difficult to handle with traditional evaporators, such as hydroquinone-containing tars.
4. Combination drying process
The paddle dryer has the unique advantages of fast heating surface renewal and high heat transfer coefficient due to the self-cleaning effect of the blade surface when processing high-moisture materials. However, it is difficult to increase the size. The configuration is complicated when processing large quantities of materials. The filling rate is high, the material layer is thick, and the drying rate decreases when drying low-water-containing materials. The disc dryer has a high agitation coefficient, low power consumption, and a thin material layer. It has a high drying rate when processing low-water-containing materials, but sticks to the disk to varying degrees when the water content is high, affecting the drying rate. The steam drum dryer is easy to be large-scale and has advantages in continuous batch processing of materials. However, like the tray dryer, it is difficult to handle high-moisture and viscous materials. Obviously, the advantages and disadvantages of these types of dryers are exactly complementary and properly combined. , Will get better economic and technological indicators. Figure 6 shows a combination of a paddle dryer and a disc dryer.
Schematic diagram of hollow paddle dryer
Take the double shaft type as an example to introduce its structure (the hollow paddle dryer can be divided into single, double and four). It consists of a jacketed end face with a W-shaped housing, an upper cover, two hollow shafts with blades, end covers at both ends, a rotary joint with a medium, a metal hose, and a transmission mechanism including gears and sprockets. composition.
The core of the hollow blade dryer is two hollow shafts and a hollow stirring blade welded to the shaft. The blade shape is a wedge-shaped hollow semi-circular, which can pass into the heating medium. In addition to the role of stirring, it is also the heat transfer body of the hollow blade dryer. The two main heat transfer sides of the blade are inclined. Therefore, when the material is in contact with the inclined surface, as the blade rotates, the particles quickly slide away from the inclined surface, which continuously updates the heat transfer surface and strengthens the heat transfer. A scraper is provided at the triangular bottom of the blade to scrape the material deposited on the bottom of the shell to prevent dead corners.
There are certain requirements for the arrangement of the paddles and the size of each part. In addition to the paddles in the feed zone, drying zone, and discharge zone, there are auxiliary mechanisms to ensure stable operation and uniform drying of the machine. In addition, the dwell time can be adjusted.
Application range of hollow paddle dryer
Hollow paddle dryer adapts to materials
The hollow paddle dryer can indirectly heat or cool pasty, granular, powdery, and slurry materials. It has been successfully used in food, chemical, petrochemical, dye, and industrial sludge fields. The characteristics of heat transfer, cooling and agitation of the hollow blade dryer make it possible to complete the following unit operations: calcination (low temperature), cooling, drying (solvent recovery), heating (melting), reaction and sterilization. The stirring blade is also a heat transfer surface, which increases the heat transfer area in the unit effective volume and shortens the processing time. The wedge-shaped blade heat transfer surface also has a self-cleaning function, and the compression-expansion stirring function makes the materials mixed uniformly. The material moves in a "piston flow" along the axial direction. In the axial interval, the temperature, humidity and mixing gradient of the material are small. If heat-conducting oil is used as the heat medium, the paddle dryer can complete the low-temperature calcination work, such as: calcination of calcium sulfate dihydrate (Ca2SO4 · 2H2O) into calcium sulfate hemihydrate (Ca2SO4 ·? H2O). Sodium bicarbonate (NaHCO3) is converted into soda ash (Na2CO3) by calcination. Cooling medium such as water and cooling brine can be used for cooling. For example, the pulp leaf type cool alkali machine used in the soda ash industry can replace the old-style air-cooled cool alkali machine, which saves energy and exhaust gas treatment equipment and reduces operating costs . The vacuum paddle dryer does not use hot air, which makes the solvent recovery, energy consumption, and environmental control ideal for easy handling. It is especially suitable for solvents that need to be recovered and flammable and oxidizable heat-sensitive materials.
Hollow Paddle Dryer Applicable Industry
Polyolefin powder, polycarbonate resin, high and low density polyethylene, linear low density polyethylene, polyacetal particles, nylon 6, nylon 66, nylon 12, acetate fiber, polyphenylene sulfide, acrylic resin, Engineering plastics, polyvinyl chloride, polyvinyl alcohol, polystyrene, polypropylene, polyester, polyoxymethylene, styrene-acrylonitrile copolymerization, and ethylene-propylene copolymerization.
Environmental protection industry
PTA sludge, electroplating sewage sludge, boiler soot, pharmaceutical factory waste residue, sugar factory waste residue, MSG factory waste residue.
Soy sauce residue, bone-based feed, distiller's grains, food scraps, apple residue, orange peel, soybean meal, chicken bone feed, fish meal, feed additives, bio-slag mud
Starch, cocoa beans, corn kernels, table salt, modified starch, medicines.
Soda ash, NPK compound fertilizer, kaolin, bentonite, white carbon black, carbon black, phosphogypsum, sodium oxide fluoride, calcium nitrate, magnesium carbonate, sodium cyanide, aluminum hydroxide, barium sulfate, calcium sulfate, calcium carbonate, Dyes, molecular sieves, saponins. Alcohol residue, oxytetracycline residue, erythromycin residue, fly ash, skin powder, clay, kaolin, phosphogypsum, red gypsum, iron oxide yellow, magnesium trisilicate, alumina, H acid, mycelium, nitrate Aniline, sodium cyanide, fenitrothion, indigo, ASN resin, 1010 antioxidant, DM accelerator.
Hollow blade dryer model description
Single shaft hollow blade dryer with a heat exchange area of 100m2;
A double-shaft hollow blade dryer with a heat exchange area of 100m2.
Hollow Paddle Dryer Ordering Instructions
Parameters and related requirements
t / d
Material main ingredients
Fine powder, granules, lumps, flakes, fibrous cakes, pastes, pastes, liquids
Initial moisture content
Moisture content of finished product
Specific gravity of wet material
t / m3
Moisture in material
? Bound moisture? Unbound moisture
Material other characteristics
Requirements for drying method
? Continuous drying? Indirect drying
Available heat source
Hollow blade dryer material requirements
Environmental requirements and requirements for material recovery
Site installation requirements
Previous drying methods or similar products
Hollow blade dryer technical parameters
Heat exchange area m2
Effective volume m3
Speed r / min
Motor power kW
Design pressure of shaft and jacket MPa
5 ~ 20
5 ~ 20
5 ~ 20
5 ~ 20
5 ~ 20
5 ~ 20
5 ~ 20
5 ~ 20
5 ~ 20
5 ~ 20
5 ~ 20
5 ~ 20
5 ~ 20
5 ~ 20
1. The above table applies to steam-heated, twin-shaft hollow paddle dryers.
2. The data in the above table are reference values. In practice, please refer to the design drawing.
3. For other specifications not listed, please consult our company.
Hollow blade dryer working chart
Hollow paddle dryer delivery site
Applicable Engineering of Hollow Paddle Dryer
Electroplating sludge drying equipment project
Electroplating sludge is mainly derived from solid wastes produced by industrial electroplating plants. These wastes are mainly produced by liquid-phase chemical treatment of various electroplating waste liquids and electrolytes. The chemical composition of electroplating sludge is relatively complicated. The main components are iron, copper, zinc and other heavy metal compounds and their soluble salts. Electroplating sludge has a large water content and complex components, and especially heavy metals are more harmful. Therefore, the reduction, harmlessness and resource disposal of electroplating sludge are the top priorities of electroplating sludge disposal.
The reduction of electroplating sludge is mainly by using a drying method. The electroplating sludge with a water content of about 75% is dried to a water content of about 40% (semi-drying), so as to meet the reduction requirements and proceed to the next step Smelting and extraction of iron, copper, zinc and other metals.
2. Printing and dyeing sludge drying equipment project
3. Domestic sludge drying equipment engineering
In urban life and production, the main sludges produced are domestic sewage sludge, industrial sewage sludge, water supply sludge, river dredging sludge, and water supply and drainage pipe network sludge. 高、危害较大和较难处置的当属生活和工业污水污泥。 Among them, domestic sewage and industrial sewage sludge are relatively large in output, high in pollution, harmful and difficult to dispose.
Hollow blade dryer engineering case
| Application: Chemical |
Customer: A company in Zhejiang
Overview: dryer model KJG-12.5
Customer: A company in Jiangsu
Overview: hollow blade dryer model DAJG-30
Application: building materials
Customer: a company in Hubei
Overview: hollow blade dryer model DAJG-100
Customer: An Anhui company
Overview: hollow blade dryer model DAJG-80
The company has a standardized production workshop, a number of sheet metal equipment, welding equipment, metal processing equipment and lifting equipment, with independent testing equipment, perfect means.
The company has professional engineers responsible for free pre-sales technical services, including: technical advice on hollow blade dryer selection, installation, use, maintenance, etc., providing hollow blade dryer and system design solutions.
2. Sale service
Under the contract principle, we will further optimize the design of the hollow blade dryer according to the user's use situation to ensure that the user is convenient to install and use. After the hollow blade dryer is installed, if we need assistance in commissioning, we will send personnel to the site for service.
3. After sales service
7 * 24 hours operation and maintenance service. During the warranty period of the product, we will repair it free of charge if it meets the conditions of use and operates correctly. Provide lifelong repair service for the products sold.