How to improve the efficiency of the paddle dryer?

The paddle dryer uses the agitation of the internal blades of the equipment to complete the drying of the material. In many industries that require drying, the paddle dryer can be seen. What are the applications of the paddle dryer? How to improve the paddle drying? What is the efficiency of the machine?

First, the characteristics of the paddle dryer

1, small footprint

The device is compact in structure and has a small footprint. It can be seen from the structure of the device that the heat required for drying is mainly provided by the hollow blade wall surface arranged on the hollow shaft, and the heat transfer amount of the jacket wall surface is only a small part. Therefore, the heat transfer surface of the unit volume equipment is large, which can save equipment footprint and reduce capital investment.

2, high heat utilization rate

Typical conduction drying method, energy saving, large conduction coefficient, high thermal efficiency; paddle dryer is heated by conduction heating, all heat transfer surfaces are covered by materials, reducing heat loss; no hot air takes away heat, heat utilization can be It is more than 90%; the stirring blade is also a heat transfer surface, which increases the heat transfer area per unit effective volume and shortens the processing time.

3, self-cleaning ability

The wedge-shaped blades have self-cleaning ability to improve the heat transfer of the blades. The blades rotate in opposite directions, and the two inclined surfaces of the blade repeatedly stir, compress, relax and propel the material, so that the page has a unique self-cleaning ability, the heating surface is continuously updated, and the heat transfer coefficient of the paddle dryer is higher than any other conduction. Drying method.

Second, what are the application areas of paddle dryers?

1. Petrochemical industry

Polyolefin powder, polycarbonate resin, high and low density polyethylene, linear low density polyethylene, polyacetal granules, nylon 6, nylon 66, nylon 12, acetate, polyphenylene sulfide, propylene based resin, Engineering plastics, polyvinyl chloride, polyvinyl alcohol, polystyrene, polypropylene, polyester, polyoxymethylene, styrene ~ acrylonitrile copolymerization, ethylene ~ propylene copolymerization.

2. Environmental protection industry

PTA sludge, electroplating sewage sludge, boiler soot, pharmaceutical factory waste, sugar factory waste, MSG factory waste, coal ash.

3. Feed industry

Soy sauce residue, bone-based feed, distiller’s grains, food scraps, apple pomace, orange peel, soybean meal, chicken bone feed, fish meal, feed additives, bio-sludge.

4. Food industry

The uniformity of temperature, humidity, and mixing in the axial section allows the equipment to be used to heat or melt, or to react with some solid materials. It has been successfully used in the compound fertilizer and modified starch industries. The paddle dryer can be used to sterilize food and flour, and the heating area in the effective volume of the unit is quickly heated to the sterilization temperature to avoid changing the quality of the material by heating for a long time. There are also starch, cocoa beans, corn kernels, salt, modified starch, and pharmaceuticals.

5. Chemical industry

Soda ash, NPK compound fertilizer, kaolin, bentonite, white carbon black, carbon black, phosphogypsum, oxidized sodium fluoride, calcium nitrate, magnesium carbonate, sodium cyanide, aluminum hydroxide, barium sulfate, calcium sulfate, calcium carbonate, Dyes, molecular sieves, saponins.

The heat transfer oil is used as the heat medium, and the paddle dryer can complete the low temperature calcination work. For example, calcium sulfate dihydrate (Ca2SO4•2H2O) is calcined and converted into calcium sulfate hemihydrate (Ca2SO4•1/2H2O). Sodium hydrogencarbonate (NaHCO3) is converted into soda ash (Na2CO3) by calcination.

Cooling medium such as water, cooled brine, etc. can be used for cooling. For example, the paddle type caustic soda machine used in the pure soda ash industry replaces the old-fashioned air-cooled alkali-alkali machine, saves the energy and quantity of materials and exhaust gas disposal equipment, reduces the operating cost, and can also be used for titanium, nickel-iron alloy powder and Cooling of various powdery materials. The material can be cooled from 1000 ° C to less than 40 ° C in a single machine.

Second, how to improve the efficiency of the paddle dryer?

1. When the paddle dryer is working, pay attention to the smoothness of the material feeding when the material is put into the material. The material and the like contain a lot of water, which is easy to bond together. If it is bonded together during the blanking, the material will block in blocks. The silo, this will cause the material to not fall down, can not enter the equipment, can not dry.

2. Humidity control during feeding, the humidity of different materials is different, some are high and some are low. When drying materials, the humidity of the slime needs to be checked, and then the materials are placed according to the corresponding standards.

3. The amount of the problem needs to be considered in the feeding of the dryer. First, whether the uniformity of material delivery is up to standard, try to avoid such fluctuations in feeding mode, and secondly, consider the drying capacity of the dryer – capacity problem, if the progress of the material is far beyond the dryer If you work, the drying work will not be completed.

4. Before entering the equipment, confirm whether dehydration treatment is needed. Some materials have too high water content and are directly dried on the machine. Not only is the time long and the efficiency is slow, the cost is greatly increased, and the drying effect is not necessarily ideal. So for this case, early dehydration is a good treatment.

5, the premise of good operation of the equipment is that there is no fault, regular inspection is to eliminate hidden dangers. In order to avoid problems and get stuck in the work, you can find the problem and solve the problem in time.

The periodic inspection of the paddle dryer is due to the special nature of the equipment, and a comprehensive technical assessment work must be carried out by the state. The inspection must be carried out by the department that has obtained the inspection qualification.

Through the inspection, the actual safety status of the paddle dryer is better grasped, and the importance of the use and management of the equipment by each user unit is improved. By testing and detecting hidden dangers, the inspection report and the rectification notice were immediately issued, which greatly improved the rectification rate and achieved good results.

Regular inspection of the paddle dryer is an important part of the equipment maintenance work, so as to master the equipment operation, work performance and wear. Prepare for repair work, improve repair quality and reduce repair time. The contents of the inspection included understanding the changes in the technical status of the paddle dryer and the wear and tear; the problems found. Propose measures for equipment repair work.

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Drying equipment type and purchase

As the name suggests, drying equipment is a machine that reduces the moisture of materials. It has a wide application field. The sludge drying equipment is used to dry sludge. The dregs drying equipment can also retain the effect of the medicine under the premise of drying the dregs. So what types of drying equipment are there? How to choose drying equipment?

Drying equipment type

1. Hollow paddle drying equipment

The hollow blade drying device, also known as the blade drying device, is mainly composed of a W-shaped casing with a jacket and two hollow blade shafts and a transmission device. Hollow blades are arranged on the shaft, and the rotary end of the heat medium is introduced at the shaft end. The heat required to dry the moisture is conducted to the material by the inner wall of the jacketed W-shaped groove and the hollow blade wall. During the drying process, the hollow shaft with hollow blades agitates the material while heating the material, thereby updating the heating surface. It is a continuous conduction heating drying equipment. The heating medium is steam, hot water or heat transfer oil. The heating medium is introduced into the casing jacket and the two hollow blade shafts to heat and dry the materials in a conductive manner, and the hollow shaft structure of different materials is different.

The machine is suitable for processing various materials with good thermal stability such as paste, granule and powder. Under special conditions, the heat sensitive material can be dried and the solvent can be recovered during the drying process. It is commonly used for drying or cooling materials such as carbon black, light calcium carbonate, barium carbonate, nitrile uric acid, gypsum, clay, manganese dioxide, nylon and polyester chips, polyethylene, polypropylene (recovery solvent).

2. Roller scraper drying equipment

The drum scraper drying device is an internal heating conduction type rotary continuous drying device. The rotating drum adheres to the film of a thickness through the lower trough, and the heat is transported to the inner wall of the drum through the pipeline, and is transmitted to the outer wall of the drum, and then the feed film is transmitted, so that the humidity in the film is evaporated and dehumidified, so as to contain The wet parts are dried. The dry material is scraped off the drum by the scraper placed on the surface of the drum, and the screw conveyor placed under the scraper is used to concentrate and package the dry material through the screw conveyor.

The drum scraper drying equipment is suitable for the drying of liquid materials and viscous materials in the chemical, dye, pharmaceutical, food, metallurgy, yeast and other industries. Widely used in: rice flour, oatmeal, alpha starch, potato whole powder and other food products dry products into flakes, powder and granules.

3. Freeze drying equipment

The refrigerating drying device cools the compressed air by heat exchange of the refrigerant during operation, and then the refrigerant is cooled and recycled. The freeze-drying equipment combines a refrigeration system, a vacuum system, a heat-conducting oil heating system, and a moisture-discharging system, and a new type of box structure, which utilizes a large amount of dry storage vacuum space for storing the material space in the tank, so that the powder after drying can be possessed. Good dispersion. It has the advantages of reducing the possibility of oxidative deterioration of the material, eliminating bacteria in the material, ensuring quality, and the original shape of the material can be well retained. The vacuum freeze-drying equipment is suitable for drying high-grade raw materials, traditional Chinese medicine decoction pieces, biological, dehydrated vegetables, chemicals, pharmaceutical intermediates and other materials. It can be seen that it is widely used in the pharmaceutical industry.

4. Double cone rotary vacuum drying equipment

The double-cone rotary vacuum dryer has a slightly olive-like shape with a cover at both ends, and two shafts are arranged in the middle to support the body. The body has a jacket to heat, and the body can be rotated when dry, so that the material and the wall are frequently replaced, which overcomes the disadvantage that the material in the vacuum oven mainly passes through the heating cylinder and has low thermal efficiency. Rotary vacuum dryers have been widely used in fine chemicals and medicines, and are not suitable for materials with high viscosity or strong adhesion during the turning process.

The equipment is mainly used for concentrating, mixing, drying and low-temperature drying materials (such as biochemical products) of powder, granular and fibrous materials in the pharmaceutical, chemical and food industries, and is more suitable for oxidizing, volatile and heat sensitive. Strongly irritating, toxic materials and drying of materials that do not allow damage to the crystals.

Drying equipment purchase

Knowing the drying equipment of so many types of specifications, our main purpose is to use it, then how to choose drying equipment? We all know that different equipment is required to handle different objects, and the factor that affects our choice of drying equipment is the nature of the material being processed. It is easy to select the appropriate drying equipment by determining the type of material. So, how to judge the material type?

1.The initial state of the material

The initial drying equipment is initially screened by determining the initial state of the material. Under normal circumstances, the materials to be dried have three states, namely solid materials, paste fluidized materials and liquid materials. For solid materials, box drying equipment, flash drying equipment, etc.; paste materials using paddle drying equipment with stirring, vacuum drying equipment, etc.; liquid materials generally use spray drying equipment, boiling drying equipment.

2. Physical and chemical properties of the material

After a preliminary selection of a range of drying equipment based on the initial state of the material, the physical and chemical properties of the material are then considered. Mainly refers to the range of temperature adaptation to ensure that the material will not be damaged by high temperatures. According to our 30 years of design theory in the south, the drying temperature of various drying equipment is as follows, box drying equipment: 60-250 ° C; flash drying equipment: 80-580 ° C; vacuum drying equipment: 0-250 ° C; Spray drying equipment: 100-500 ° C.

3. Calculate the specific amount

Determine the appropriate drying equipment by calculating the required heat and air volume based on the initial and final moisture of the material to be dried.

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Sludge dryer working principle, performance characteristics and parameters

The sludge dryer is a product upgraded and upgraded by our factory on the basis of the original blade dryer. The equipment has high thermal efficiency; the sludge dryer can indirectly heat or cool the paste, granular, powder and slurry materials. Unit operations such as drying, cooling, heating, sterilization, reaction, and low temperature combustion. The special wedge-type stirring heat transfer blade in the equipment has high heat transfer efficiency and self-cleaning function of the heat transfer surface.

Sludge dryer working principle

A hollow hollow blade is densely arranged on the hollow shaft, and the heat medium flows through the blade through the hollow shaft. The heat transfer area in the effective volume per unit is large, and the temperature of the heat medium is from -40 ° C to 320 ° C. It can be water vapor or liquid type: such as hot water and heat transfer oil. Indirect conduction heating, no air is carried away to remove heat, and heat is used to heat the material. The heat loss is only the heat dissipation to the environment through the insulation of the body. The wedge-shaped blade heat transfer surface has a self-cleaning function. The relative movement of the material particles and the wedge surface produces a scrubbing action, which can wash away the adhering material on the wedge surface, so that a clean heat transfer surface is maintained during operation. The shell of the paddle dryer is of the omega type, and two to four hollow agitating shafts are generally arranged in the casing. The housing has a sealed end cover and an upper cover to prevent material dust from leaking out and fully functioning.

The heat transfer medium passes through the rotary joint and flows through the casing jacket and the hollow agitating shaft. The hollow agitating shaft has different internal structures according to the type of the heat medium to ensure a good heat transfer effect.

Performance characteristics

(1) Low energy consumption of sludge dryer: Due to indirect heating, there is not a large amount of air carrying heat, and the outer wall of the dryer is provided with an insulation layer. For the slurry material, only 1.2 kg of water vapor is required to evaporate 1 kg of water.

(2) Low cost of the blade dryer system: The huge heat transfer surface in the effective volume of the unit shortens the processing time and the size of the device becomes smaller. It greatly reduces the building area and building space.

(3) Wide range of processing materials: Different heat media can be used to process both heat sensitive materials and materials requiring high temperature treatment. Commonly used media are: water vapor, heat transfer oil, hot water, cooling water, etc. It can be operated continuously or intermittently and can be applied in many fields.

(4) Small environmental pollution: No air is carried in, and dust materials are rarely entrained. The solvent evaporation of the material is small and easy to handle. For contaminated materials or conditions requiring recovery of solvents,Closed loop.

(5) Low operating cost: structure. The amount of wear is small and the maintenance cost is low.

(6) Stable operation: Due to the special compression-expansion stirring effect of the wedge-shaped blade, the material particles are fully in contact with the heat transfer surface, and the temperature, humidity and mixing gradient of the material are small in the axial interval, thereby ensuring The stability of the process.

Adaptable material

The paddle dryer has been successfully used in food, chemical, petrochemical, dye, industrial sludge and other fields. The heat transfer, cooling, and agitation characteristics of the equipment enable it to perform the following unit operations: combustion (low temperature), cooling, drying (solvent recovery) heating (melting), reaction, and sterilization. The agitating paddle is also a heat transfer surface, which increases the heat transfer area per unit effective volume and shortens the processing time.
The wedge-shaped blade heat transfer surface has a self-cleaning function. Compression – the expansion and agitation function makes the material mix evenly. The material moves in a “plug flow” along the axial direction, and the temperature, humidity, and mixing gradient of the material are small in the axial interval. Low temperature combustion can be accomplished by using a heat transfer oil as a hot medium paddle dryer. For example, calcium sulfate dihydrate (Ca2SO4•2H2O) is converted into calcium sulfate hemihydrate (Ca2SO4•1/22H2O). Sodium hydrogencarbonate (NaHCO3) is calcined to be converted into soda ash (Na2HCO3) or the like.

Cooling medium such as water, cooled brine, etc. can be used for cooling. For example, the paddle type alkali machine used in the soda ash industry replaces the old air-cooled alkali machine, which saves energy and exhaust gas treatment equipment and reduces operating costs. Dry, the main function of the equipment, without the use of hot air, so that solvent recovery, energy consumption, environmental control is in an ideal state of easy handling. It is especially suitable for the need to recover solvents, flammable and easy to oxidize heat sensitive materials. Has been widely used in fine chemicals, petrochemicals, dyes industry. The uniformity of temperature, humidity, and mixing in the axial section allows the equipment to be used to heat or melt, or to react with some solid materials. It has been successfully used in the compound fertilizer and modified starch industries. A paddle dryer can be used to sterilize food and flour. The large heating area in the effective volume of the unit quickly heats the material to the sterilization temperature, avoiding prolonged heating and changing the quality of the material.

Technical specifications

Project model JYG3 JYG9 JYG13 JYG18 JYG29 JYG41 JYG52 JYG68 JYG81 JYG95 YJG110
Heat transfer area（m2） 3 9 13 18 29 41 52 68 81 95 110
Effective volume（m3） 0.06 0.32 0.59 0.59 1.85 2.8 3.96 5.21 6.43 8.07 9.46
range of rotation（rmp） 15-30 10-25 10-25 10-20 10-20 10-20 10-20 10-20 5-15 5-15 5-10
power（kw） 2.2 4 5.5 7.5 11 15 30 45 55 75 95
Body widthA（mm） 306 584 762 940 1118 1296 1476 1652 1828 2032 2210
Total width B（mm） 736 841 1066 1320 1474 1676 1854 2134 1186 2438 2668
Body width C（mm） 1956 2820 3048 3328 4114 4724 5258 5842 6020 6124 6122
Total length D（mm） 2972 4876 5486 5918 6808 7570 8306 9296 9678 9704 9880
In and out materialE（mm） 1752 2540 2768 3048 3810 4420 4954 5384 5562 5664 5664
Center height F（mm） 380 380 534 610 762 915 1066 1220 1220 1220 1220
Total height H（mm） 762 838 1092 1270 1524 1778 2032 2362 2464 2566 2668
Steam inlet N（寸） 3/4 3/4 1 1 1 1 11/2 11/2 11/2 11/2 2
Outlet O（寸） 3/4 3/4 1 1 1 1 11/2 11/2 11/2 11/2 2
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Rotary vacuum pad dryer introduction

The rotary vacuum paddle dryer is a jacketed cylindrical container with a large diameter hollow shaft, connected to the shaft is a hollow blade with a specially designed scraper that scrapes the entire inner surface of the dryer And continuously moving and rotating the material to eliminate the possibility of the material remaining in contact with the hot surface for a long time.

The jacket with the blades and the hollow shaft can be heated with hot water, steam or any other hot fluid capable of providing a large indirect heat transfer area. It can also be cooled by water, brine or any other refrigerant through the jacket and hollow shaft. If a liquid heating medium is used, a coil can be provided instead of the sheath. The hard surface of the shaft is placed in the gland packing area of ​​the trunnion to provide a nitrogen purge arrangement. A pulsating bag cleaning device is provided by a nitrogen ejector.

Heavy-duty bearings and bearings support hollow shafts (mixers), which are supplied by motors that reduce the gear train and sprocket. It is also provided that four crush bars are inserted into the dryer housing to reduce the particle size. In special cases, a fixed scraper can be provided to discard the rotary agitator for highly viscous materials.

working principle

Rotary vacuum paddle dryer has the advantages of high technology content, high standardization, environmental protection, safety, low consumption, simple maintenance, etc. In the design structure:

The top of the rotary vacuum dryer is equipped with a classifier. By changing the hole diameter of the classifier and the height of the classification section, the air flow rate is changed, and the particle size and quantity leaving the dryer, the final water content and the material in the drying section are controlled. Stay time. The bottom of the rotary vacuum paddle dryer is provided with an inverted cone structure, so that the cross section of the drying gas gradually expands from bottom to top, the bottom airflow is relatively large, and the upper airflow is relatively small, thereby ensuring that the lower large particles are in a fluidized state. The upper small particles are also in a fluidized state, and the hot air is rotated along the vertebral body, the bottom wind speed is increased, the length of the cantilever portion of the stirring shaft is reduced, the safety and reliability of the operation are increased, and the bearing can be placed outside the machine, effectively Prevents the bearing from working in the high temperature zone, thus extending the service life of the bearing.

The number of revolutions of the rotary shaft of the rotary vacuum dryer is controlled by a stepless speed regulating motor. Different speeds are selected according to the product particle size requirements. The faster the stirring shaft speed, the smaller the particle size of the obtained product. A scraper is arranged on the stirring tooth, and the material is thrown to the wall of the machine while being crushed by the stirring tooth, and is bonded to the wall surface. If it is not scraped in time, the equipment may vibrate in severe cases, and even the stirrer may be suffocated. A scraper is arranged on the stirring tooth to peel off the material adhering to the machine wall in time to avoid sticking.
The number of revolutions of the screw conveyor of the rotary vacuum paddle dryer is controlled by an inorganic speed control motor. The feed rate is controlled according to the nature of the material and the drying process parameters. The flash dryer has compact structure, small footprint, integrated drying, pulverization and grading. It is an organic combination of swirling technology, fluidization technology, spray technology and convection technology. It does not need to be crushed or sieved after drying. Simplifies the production process and saves on power and equipment costs.

Design and application of rotary vacuum paddle dryer

A rotary vacuum paddle dryer is a drying system for obtaining dry powder from a wet cake or solution. The drying operation is usually a batch process and is usually carried out under vacuum, heating the product by direct contact with the heating vessel and the surface of the agitator. The heating of the dryer can be accomplished by using steam or a suitable heat transfer fluid.

The paddle dryer is designed to withstand the stresses caused by vacuum and temperature cycling in various heating components. The standard design of the paddle dryer system includes a dust collector, condenser, receiver and vacuum pump. Other features include:

Hollow shafts and blades: Hollow rotary mixers provide heat to the product, scrape the shell wall, flip the product to a large extent to transfer heat, and discharge the product when needed.
Drain valve: User-friendly design provides a tight vacuum closure during material processing and quick opening of the bag during material removal and packaging.

Rotary vacuum paddle dryer process design method

The new equipment of rotary flash dryer adopts a variety of advanced devices. For example, a variety of feeding devices are used to make the feeding continuous and stable, and the feeding process does not cause bridging; the bottom of the dryer uses a special cooling device to avoid the material in the bottom high temperature zone. Sticking wall and deterioration phenomenon occur; special air pressure sealing device and bearing cooling device are used to effectively extend the service life of the transmission part; special air separation device is adopted to reduce the resistance of the equipment and effectively provide the treatment air volume of the dryer; drying room It is equipped with a grading ring and a swirling plate to adjust the fineness and final moisture of the material. The stirring and pulverizing device is used to produce strong shearing, blowing and rotating effects on the material; air filter, cyclone separator, bag filter, etc. are used. Effectively remove dust and avoid environmental and material pollution. The device has strong mass transfer heat transfer, high production intensity, short drying time and short material residence time.

First, the determination of the drying room

Rotary vacuum paddle dryers process the evaporation intensity of some materials. The volumetric heating method is the theoretical design method of rotary flash dryer. However, the key volumetric heat coefficient in this method is difficult to determine, so it lacks operability. Evaporation intensity method is an indirect method of volumetric heating method. It can be calculated as long as there is certain experimental data. It is a method commonly used in industrial design. The evaporation strength method calculates the volume of the drying chamber based on the amount of evaporated water and the evaporation strength, and calculates the effective height based on the relationship between the diameter and the height.

Second, the diameter of the drying chamber

Another method is to calculate the required air consumption by material balance and heat balance, and then determine the diameter of the dryer according to the air speed range.

Third, the height of the dryer and the graded particle size

The hot air from the hot air distributor enters the drying chamber through the annular gap in a tangential direction, and the material in the drying chamber is spirally rotated and raised under the action of the hot air blowing and the agitator. When studying the fluid motion of smaller particles under the action of the centrifugal force field, the effect of gravity is small and therefore negligible.

Fourth, the application of rotary vacuum pad dryer

The operating conditions of the partial rotary vacuum pad dryer, the upper part of the drying chamber is provided with a step ring, the main function of which is to separate the material with large or no dry particles from the qualified product, and the product can effectively ensure the product size and moisture requirement in the drying chamber. . Replacing the grading rings of different diameters can meet the product size requirements. Cold air protection is provided at the hot air population at the bottom of the cone to prevent the material from coming into contact with high temperature air to cause overheating. The drying system is closed and operates under micro-negative pressure. The dust does not leak, protecting the production environment, and being safe and hygienic.

Rotary vacuum paddle dryer is mainly composed of air inlet system, heating system, feeding system, drying host, receiving dust removal system, exhaust system and control system. During operation, the wet material enters the drying chamber by the screw feeder, and the material meets the hot air rotating at high speed in the drying chamber, and the fine powder material is moved by the hot air to the upper end of the drying chamber, and the material that cannot be taken falls at the bottom of the drying chamber. It is broken by the crushing device at the bottom, the material is quickly dispersed, and the contact area between the material and the hot air is rapidly increased. Under the action of centrifugal force (with a classification device at the top), the product that reaches the degree of dryness and a certain degree of fineness is blown out of the classifying device, and the material is quickly dried in the process.

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What are the factors to consider when choosing a paddle dryer?

The hollow blade dryer consists of two blade shafts that mesh with each other, a W-shaped casing with a jacket, a machine base and a transmission part. The entire drying process of the sludge is carried out in a closed state, and the organic volatile gas and the odor gas are It is sent to the exhaust gas treatment device in a sealed atmosphere to avoid environmental pollution.

The dryer uses steam, hot water or heat transfer oil as the heating medium, and the shaft end is equipped with a rotary joint for introducing and exporting the heat medium. The heating medium is divided into two paths, respectively entering the jacket of the dryer casing and the inner cavity of the blade shaft, heating the body and the blade shaft at the same time, and heating and drying the sludge by conduction heating.

The dried material is continuously and continuously fed into the dryer feeding port by the screw feeder. After the material enters the blade, the material is turned and stirred by the rotation of the blade, and the heating interface is continuously changed, and the body and the blade are in contact with each other. Heating to evaporate the surface moisture contained in the sludge. At the same time, the material is conveyed in the direction of the discharge port with the rotation of the blade shaft in a spiral path, and the stirring is continued during the transportation, so that the water oozing out from the sludge continues to evaporate. The uniformly dried product is then discharged from the discharge port.

Features

1. The equipment is compact in structure and the device covers a small area. It can be seen from the structure of the device that the heat required for drying is mainly provided by the hollow blade wall surface arranged on the hollow shaft, and the heat transfer amount of the jacket wall surface is only a small part. Therefore, the heat transfer area per unit volume of equipment is large, which can save equipment footprint and reduce capital investment;

2. High heat utilization rate. The paddle dryer is heated by conduction heating, and all heat transfer surfaces are covered by materials, which reduces heat loss; no air takes away heat, and the heat utilization rate can reach 80% or more;

3. The wedge-shaped blade has self-cleaning ability, which can improve the blade conduction. The dispersing force generated by the combined movement of the inclined surface of the rotating blade and the particle or powder layer causes the material attached to the heating ramp to be automatically removed, and the blade maintains an efficient heat transfer function. In addition, due to the reverse rotation of the two-axis blades, the alternating section compression (when the two-axis blade faces are close together) and the expansion (when the two-axis blade faces are far apart), the heat transfer is uniform and the heat transfer is uniform. Heat transfer effect;

4. Since no gas is needed for heating, only a small amount of gas is needed to take away the humid air. The gas velocity in the dryer is low, and the dust emitted by the gas is less, and the gas dust recovery of the system after drying is convenient;

5. The material moisture content has wide adaptability and the product has uniform drying uniformity. The dryer is provided with an overflow weir, which can adjust the residence time of the material in the dryer according to the nature of the material and the drying conditions to meet the requirements of the moisture content change of the material. In addition, the feed rate, the rotational speed of the shaft, and the temperature of the heat carrier can be adjusted, and the residence time can be arbitrarily selected between several minutes and several hours. Therefore, the adaptability to the change of moisture content of materials is very wide;

6. The feeding adopts the shaftless screw conveyor, which can transport the muddy materials with high viscosity and high moisture content;

When selecting a paddle dryer, the following factors are mainly considered.

1. Heat source, heat transfer medium and heat loss

The expenditure on drying heat accounts for 60% to 75% of the operating cost of the drying system, or even higher. Therefore, the study of heat source selection and reduction of heat loss is the top priority for the evaluation of the blade dryer drying system.

2. Security

A certain amount of dust will be generated during the hot drying process of the sludge. When the dust reaches a certain concentration, and the oxygen content and temperature are satisfied, explosion or deflagration may occur. Dust explosion accidents are not uncommon at home and abroad, and should be given enough attention.

3. Impact on the environment

In the process of drying, the sludge not only produces odorous gases such as ammonia gas and hydrogen sulfide, but also toxic substances such as benzene, phenol and corresponding compounds. In the process design, the volatilization of these substances should be reduced as much as possible, and the volatilized gas should be properly disposed to avoid gas leakage.

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Application of hollow paddle drying technology in the production of polyvinyl alcohol

Polyvinyl alcohol (PVA) is an important organic chemical raw material widely used in the fields of emulsions, coatings, adhesives and fiber auxiliaries. Polyvinyl alcohol drying is the last key step in the product and directly affects product quality. The main volatiles of polyvinyl alcohol are methanol and acetic acid, which are flammable, explosive and toxic substances. They have high requirements on drying safety, and the product grades are up to 30 kinds. The physical properties of various grades are large, dry. It is easy to agglomerate and stick to the wall. After investigation and research, it was decided to adopt a two-stage drying process of polyvinyl alcohol hollow blade, which was ideal after use.

Drying status and problems of polyvinyl alcohol

The rake dryer is commonly used in the conventional drying process of polyvinyl alcohol, and the following problems mainly exist:
The dryer is bulky and has low heat transfer efficiency. The domestic dry type of polyvinyl alcohol with a dry treatment capacity of 1 t / h is 2.8 m in diameter and 25 to 30 m in length. The dryer only transfers heat by the wall of the clamp sleeve, the inner wall has a thickness of 20 mm, the heat transfer coefficient is small, and the heat transfer effect is poor, especially after the inner wall is bonded, the heat transfer efficiency is lower.

There is a dry corner and a sticky wall. A dry dead zone is formed at the temperature measurement point inside the dryer, the bearing seat and the end plate where the tweezers cannot be scraped. In addition, due to the long barrel of the equipment, the concentricity of the cylinder is not guaranteed, the gap between the rafter and the wall of the cylinder is not uniform (10-20 mm), some materials cannot be scraped, and the long-term operation will be crusted and adhered to the wall. Usually, it is necessary to clean the internal leather material after running for more than one month, otherwise the yellow dot material will be mixed in the product, which will affect the product quality.

It is difficult to clean up and the failure rate is high. The tweezers and bearing blocks in the dryer affect the person to clean inside. Each cleaning needs to stop for a day or so, and the temperature and temperature rise are also slow, resulting in longer parking time, which directly affects the output of the product. The tweezers of the dryer are connected to the shaft by the connecting arm. The connecting bolts are often loosened by the vibration of the running vibration and the temperature, and the tweezers will scrape the wall, causing the bending of the tweezers and the connecting arms, and must be stopped at this time.

The two internal bearings cannot be refueled during operation. The bearings are short of oil during operation and the bearings are damaged frequently. The main shaft of the bearing is generally divided into three sections and three sections. The small section of the solid shaft and the large section of the hollow shaft are connected by flat keys. When the scraping wall and the tweezer are damaged, the flat key is often overloaded, and the shearing damage of the key occurs. Frequent opening and closing has a great impact on continuous production, which not only causes the increase of material consumption, but also increases the probability of occurrence of non-conforming products and the increase of by-products, which brings difficulty and trouble to the process operation, and ultimately affects the quality of polyvinyl alcohol products.

Two-stage drying technology process of polyvinyl alcohol hollow blade

The wet polyvinyl alcohol granules from the press are mixed with the dry polyvinyl alcohol granules from the external returning system into the primary paddle dryer. The dryer hot shaft and the paddle blades are hollow, the inside is steamed, and the material is along with the hot axis. The rotation gradually moves toward the discharge end while receiving the heat transferred from the hot shaft and the blade, the temperature of the material rises, and the moisture is vaporized. The primary dryer is the main drying unit for the drying of polyvinyl alcohol, which accounts for 70% of the total dryness.

After the first stage drying, the material enters the second-stage drying, and the moisture in the material continues to evaporate through the indirect heat transfer between the hot shaft and the blade. Finally, after the drying is passed, the dryer overflows and exits the drying system to enter the vibrating screen. Large particles and agglomerated products are discharged from the waste port. Most of the dry particles of polyvinyl alcohol that meet the requirements are discharged for packaging, and some of the qualified products are returned to the drying system through the return system. The volatilization of the second-stage dry evaporation enters the first-stage dryer through the feed port of the first-stage dryer, mixes with the first-stage dried volatiles, and then draws out from the first-stage dryer into the condensation by the negative pressure generated by the decompression and suction system. recycling system.

Paddle dryer structure

The main equipment in the polyvinyl alcohol drying process system is a paddle dryer, which is a heat conduction type drying device, which is composed of a hot shaft, a fuselage, an end plate, an upper cover and a transmission system. The heat exchange surface of the dryer is mainly two hot shafts, wedge-shaped blades and a casing with honeycomb jacket. The wedge-shaped blades on the hot shaft are the main heating surface, and the heat exchange area accounts for more than 70% of the total heat exchange area.

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Sludge dryer drying process principle

As environmental protection continued to advance, everyone began to notice the pollution of sludge. If the sludge is placed in the environment without being treated, it will directly cause secondary pollution of the water body and the atmosphere, posing a threat to the ecological environment. At this time, a sludge dryer became an important weapon to save sludge pollution.

1. Adaptability:
The sludge dryer has strong adaptability to various sludges and can effectively dry sludge. With a mature design and production process, the drying system can adjust the solid content, which fundamentally guarantees the feasibility of the project. In the actual operation process, the solid content of the sludge can be adjusted in real time according to the actual operating conditions to achieve optimal operation of the entire system.

2. Security:
The safety during sludge drying is mainly related to the control of oxygen and dust. The sludge dryer drying process technology does not have dry sludge backmixing. Therefore, there is no dry sludge in the system, the flow rate of the material is small, and the amount of dust is substantially zero. The process gases in the system are primarily odors in steam and sludge, and the oxygen content of the system is very loose in a completely inert operating environment. This ensures safety during the drying process.

3. high efficiency:
The heat required for the sludge dryer is not provided by hot gas. Due to the compact structure of the equipment and the small number of auxiliary devices, the heat loss is also reduced, and the heat utilization rate can reach 80%-90%.

The RD sludge dryer is suitable for treating various sludges with good thermal stability such as paste, granules and powder. Under special conditions, the heat sensitive materials can be dried and the solvent can be recovered during the drying process. At the same time, the drying process must be energy-saving, environmentally friendly, and the operation of drying equipment must implement “five basic principles”.

First, maximize the specific surface area of ​​the material to be dried (minimized bare evaporation particles)

The specific surface area (including pores) in the evaporation process is caused by reducing the thermal energy conduction path, reducing the kinetic energy consumption (non-evaporation energy) formed by the water migration path, reducing the surface heat energy loss accumulated by the evaporation time, and lowering the gasification temperature. Basic energy consumption, increase the humidity of the exhaust gas and reduce the heat energy loss caused by the exhaust gas emissions.

The internal moisture of the material must form a pressure-bearing steam through the heat to overcome the resistance (f) of the migration path (R) to discharge the surface of the particle. The thermal energy (Q) is the conduction between the materials, which requires the time and excess energy to be transferred. , an important factor is the length of its conduction path (R);
For the same mass of water molecules, the kinetic energy consumed by the migration motion is the positive function of the moving resistance (f) and the path (R), which increases significantly as the moving path (R) increases. These kinetic energy are in the drying process. Both are transformed from heat. Therefore, in the case where the surface tension (Fr) of the same material condition is constant, the larger the path (R), the higher the thermal energy consumed (with the vaporization of moisture).

Combining the above basic processes of heat transfer and evaporation, it is easy to see that the heat energy consumed by evaporation increases with the increase of the path (R) and is a positive function value. “Specific surface area” is inversely proportional to “path”. “Specific surface area” and “evaporative heat energy consumption” are inverse function values.

Second, the drying power of the drying chamber is maximized

Drying power: The ability of water (or solution) to migrate (evaporate) from the outside of the material. It is determined by the difference between the vapor partial pressure or relative humidity (RH) of the material and the adjacent object. The greater the difference, the greater the ability to move or transfer. The relative humidity (φ1~φ5) of the step type in the object gradually increases. When φ1 is small and φ5 is large, the difference in the relative humidity (RH) of the step becomes more obvious, and the water migration ability is large. When φ1 is close to φ5, the difference in the relative humidity (RH) of the step is reduced, and the water migration ability (evaporation intensity) is small. This is the reason why the evaporation intensity is low when the moisture content of the material in the drying equipment is small under the same conditions.

Similarly, in the normal pressure state, when the surface of the material φ1 evaporates water and accumulates, the relative humidity (RH) increases during the evaporation process, and the evaporated water is removed in time to maintain the relative level of relative humidity (RH), which is also to enhance the evaporation intensity. key.

Third, mechanical kinetic energy is minimized

Mechanical kinetic energy (power consumption) not only reflects the problem of direct electricity consumption, but also the mechanical maintenance rate, maintenance cost, and equipment service life.

Under the same conditions, the mechanical kinetic energy required for the operation of the equipment is reflected by the resistance, friction and torque during the operation of the equipment. The higher the power consumption of the mechanical transmission, the greater the resistance, friction and torque during the operation of the equipment.

Resistance, friction and torque are the key factors affecting the operation of the equipment: There are sand grains remaining in the sludge, and the residual sludge in the municipal sludge is particularly obvious. In the drying equipment like the “dugger” working condition, the resistance and friction cause the equipment to wear rapidly, the frequency of maintenance and shutdown increases sharply, the actual service life and annual working time are greatly reduced, and the maintenance cost is increased.

The increase in maintenance rate will lead to a reduction in actual economic benefits: Operating rates and maintenance costs are an integral part of economic performance. Downtime means loss, and repair represents an increase in costs.

Fourth, the process conditions in accordance with the object to be dried

The outlet of sludge is resource-based, and sludge granulation is the key to high-efficiency resource utilization: Industrialization, economical and rapid fertilizer production: The hollow particles can provide sufficient oxygen, temperature and moisture for aerobic bacteria to achieve rapid ripening. fat. Many industrial sludges, residues and pollution-free municipal sludge can be made into organic fertilizers to achieve biological recycling and improve social benefits. Rapid carbonization of economical sludge advancement: Sludge carbonation is a good prospect for soil improvement. Hollow granulation: It can improve carbonization penetration, achieve rapid carbonization, improve the disposal capacity of a single carbonization equipment, reduce equipment investment in carbonization furnaces, reduce heat loss in carbonization process, and reduce operating costs.

Gas permeability required for pyrolysis gasification: Particle + porosity is the key to sludge pyrolysis gasification; the particle has a small specific gravity and good gas permeability, which is conducive to the penetration of combustion gas, resulting in a lower burning rate; The free carbon in the sludge is high, and the pores contribute to the escape of free carbon.

The cement kiln cooperates with sludge treatment to realize the loss of landslide in the building materials industry, and achieves the project of engineering and technological transformation and upgrading: hollow granular sludge: ensuring rapid ignition and uniform rapid calcination; ensuring long-term residence in the rotary kiln for calcination, avoiding powder The body directly enters the finished cement product with the airflow (not completely burned), which leads to the deterioration of the cement quality; complete combustion completely and ensuring the quality of the cement.

Collaborative disposal of domestic waste-to-energy projects: The largest space for domestic waste incineration is synergistic disposal of sludge. The waste heat (ignored) generated by domestic waste incineration is used to provide heat, and the sludge disposal fee is only 10 yuan/t of sludge. The granulation of sludge ensures sufficient gas permeability in the garbage heap and does not block the combustion air passage; the porosity ensures that water is absorbed in the garbage heap, and in the summer rainy season, the average moisture content of the garbage is reduced, and the average calorific value of the garbage is increased. Uniformity of combustion;

Solving the high cost of hazardous waste sludge operation: Drying the sludge with waste heat steam from hazardous waste incineration reduces the fuel consumption of wet sludge incineration, and granulation ensures a lower combustion discretion rate.

Implementation of environmentally friendly thermal power projects: The real way for coal-fired power to integrate into environmentally friendly thermal power is sludge granulation. The calorific value of the sludge is relatively low and the ignition point is high. If it is powdered sludge, when it is mixed into the pulverized coal furnace, the pulverized coal is ignited in the normal combustion space, and the sludge is often completely burned when it is transferred to the heat exchange boiler because of the high ignition point, resulting in serious incompleteness. Burning phenomenon. The gravity of the granular sludge ensures sufficient residence time in the fluidized bed; the porosity ensures rapid ignition of the particles in the furnace and eliminates incomplete combustion.

Comprehensive disposal of river sediment: Granulation is a reliable guarantee for the recycling of river sludge and trouble-free operation. It can automatically remove the foreign matter in the sediment and move the working platform.

Fifth, the basic conditions for safety and environmental protection

Sludge granulation is an important measure to prevent powder explosion and ensure safe operation. Indirect heat exchange is an important guarantee to reduce tail gas emissions, reduce tail gas treatment costs, eliminate secondary pollution, and establish a “conscience-friendly” image.

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What are the precautions for the paddle dryer installation process?

The hollow blade dryer is also called a paddle dryer. It consists of a jacketed casing, a double-helical drying conveyor shaft, a drive mechanism, a top cover, and a moisture exhaust system. A heating medium is introduced into the outer casing jacket and the drying conveyor shaft. The heat source is mainly steam, heat transfer oil and hot water.

The paddle dryer installation is transported from the production plant to the construction site. With the help of some tools and instruments, the paddle dryer is properly installed to the predetermined position and the conditions of use are met through commissioning. Whether the paddle dryer can be put into production smoothly, whether it can fully exert its performance, extend the service life of the equipment and improve the quality of the production products depends largely on the quality of the paddle dryer installation.

The various installation procedures of the paddle dryer generally have to go through: lifting and transporting, equipment unpacking inspection, pay-off position, equipment fixing, cleaning, parts assembly and component assembly adjustment, commissioning and engineering acceptance. The difference is that in these processes, different methods are used for different paddle dryers. It mainly includes transportation of equipment, assembly of whole and parts of paddle dryer, installation of pipe fittings, cutting and welding, assembly of internal parts of various containers, installation of electric motors, installation and commissioning of instrumentation and automatic control devices, pressure test and Trial operation and other work.

First of all, we must strictly guarantee the quality of equipment installation. We must carry out proper construction according to the design drawings, equipment structure drawings, installation instructions and construction acceptance specifications, quality inspection and evaluation standards and operating procedures. Secondly, we must adopt scientific construction methods to speed up the progress of the project. Guaranteed to put into production on schedule.

Paddle dryer installation precautions

(1) Before installation, carefully read the manual and related documents of the main unit and auxiliary machine to develop a detailed installation plan. Before installation, check the number and integrity of all equipments one by one according to the packing list. Check for foreign matter inside and outside the equipment.

(2) Inspect each foundation strength, size, elevation, flatness, anchor bolt holes, etc., in accordance with design requirements. Clean or purge the base surface and bolts to the buried holes to remove debris, grease and ash.

(3) The main machine is inclined at a certain angle according to the design requirements, or installed horizontally. After installation, tighten the anchor bolts.

(4) Install parts and accessories that are shipped separately at the factory according to the instruction manual or other indicative documents.

(5) The steam trap is generally purchased by the customer. It should be properly selected according to the process requirements. The displacement and drainage pressure are suitable, the drainage is thorough, and the gas is discharged. The trap should be installed at the lower part of the equipment, and the pipeline should be provided with a bypass valve. If the trap is connected to the water storage tank or directly to the boiler room, a check valve should be installed behind the trap.

(6) On the pipe network of the steam inlet, pressure regulating valves, pressure gauges and safety valves shall be provided to limit the high steam pressure to avoid accidental damage to the machine.

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Scope of conduction heat transfer drying equipment

Conductive drying, also known as contact drying, is very suitable for wet particles, while conductive dryers are more thermally efficient. Evaporated water vapor or organic solvent is withdrawn by vacuum or with a small amount of gas stream, which is the main carrier of moisture, and vacuum operation is recommended for heat sensitive granular materials. In a conduction dryer, a paddle dryer is used to dry the paste material. Rotary dryers with internal flow tubes have been designed and put into use. Vacuum drying is expensive, except that the material must be dried under low temperature or anoxic conditions, or when the material is dried under heating medium and high temperature, vacuum drying is recommended.

For a certain evaporation efficiency, it is more effective to use high temperature operation, which can reduce the gas flow rate and reduce the volume of the equipment. For low temperature drying operations, a suitable low temperature waste heat or solar collector can be selected as the heat source, but the dryer is relatively bulky. Freeze drying is a special case of drying under vacuum conditions.

Here, the temperature is below the three-state point of water, and water (or ice) is directly sublimated into water vapor. Although sublimation requires several times less heat than evaporation, other aspects of power consumption are greater, so vacuum drying costs are expensive. In the conduction heat transfer, heat is supplied to the dry material by a jacket, a stirring, a heat transfer tube, etc., and the heat medium is used instead of the hot air. A representative device is a slotted cylinder dryer. Conical stirring dryer, jacket and built-in heating tube rotary dryer, drum dryer, rake dryer, vacuum belt dryer, vacuum freeze dryer, etc. In hot air drying, the temperature during the constant-speed drying period corresponds to the wet bulb temperature.

In conduction heat transfer drying, it is necessary to artificially create a heating surface, so that the heat transfer area is small and the heat transfer coefficient is increased. In this way, the structure is more complicated and the equipment investment is larger than that of the hot air dryer. The conduction drying method indirectly transfers the heat required for drying through a surface such as a metal. The drying rate is lower than the direct drying method. The product temperature during constant-speed drying has no relationship with the temperature of the heating source, and is substantially the same as the saturation temperature of the gas pressure in the apparatus. In order to increase the drying rate and prevent uneven drying, mechanical agitation or the rotation of the container itself is usually used to increase or continuously update the heat transfer surface of the material, so it is necessary to further study the adhesion problem of the heat transfer mechanism.

The drying unit itself is expensive, but it is characterized by a small load on the dust collecting system, high thermal efficiency, easy recovery of the solvent, and the total cost is much cheaper than the direct drying method.

(1) The hollow paddle dryer, also known as the blade dryer, is mainly composed of a jacketed W-shaped casing and two hollow blade shafts and a transmission device. Hollow blades are arranged on the shaft, and the rotary end of the heat medium is introduced at the shaft end. The heat required to dry the moisture is conducted to the material by the inner wall of the jacketed W-shaped groove and the hollow blade wall. During the drying process, the hollow shaft with hollow blades agitates the material while heating the material, thereby updating the heating surface. It is a continuous conduction heating dryer. The heating medium is steam, hot water or heat transfer oil.

The heating medium is introduced into the casing jacket and the two hollow blade shafts to heat and dry the materials in a conductive manner, and the hollow shaft structure of different materials is different. The machine is suitable for processing various materials with good thermal stability such as paste, granule and powder. Under special conditions, the heat sensitive material can be dried and the solvent can be recovered during the drying process. It is commonly used for drying or cooling materials such as carbon black, light calcium carbonate, titanium dioxide, barium carbonate, nitrile uric acid, gypsum, clay, manganese dioxide, nylon and polyester chips, polyethylene, polypropylene (recovery solvent).

(2) The vacuum drier dryer is added from the top of the casing of the vacuum kneading dryer. Under the stirring of the rotating caries, the surface is continuously updated when the material is in contact with the casing wall, and the dried material is subjected to steam ( Or hot water, heat transfer oil) indirect heating, but the material moisture vaporization, vaporized moisture is pumped away by the vacuum pump in time. The material to be dried is indirectly heated by the heat carrier to vaporize the water in the material, and the vaporized water is discharged by the vacuum pump in time.

Due to the high degree of operating vacuum, generally in the range of 400-700 mmHg, the water vapor pressure on the surface of the dried material is much larger than the water vapor pressure in the evaporation space in the dryer housing. Thereby, it is beneficial to discharge the internal moisture and surface moisture of the material to be dried, and is beneficial to the movement of water molecules of the dried material to achieve the purpose of drying. The vacuum kneading dryer is suitable for heat sensitive materials that are easily oxidized at high temperatures or materials that are easy to be kneaded during drying, and materials that must be recovered from steam discharged during drying. Typical dry materials are sodium propylene sulfonate, CMC, phthalocyanine blue, dye intermediates, carboxymethyl starch, maltodextrin, hydrazine sulfonic acid and the like.

(3) The belt dryer consists of several independent unit sections. Each unit section includes a circulating fan, a heating device, a separate or common fresh air intake system, and an exhaust gas exhaust system. The operating parameters of the amount of drying medium, temperature, humidity and exhaust gas circulation can be independently controlled to ensure the reliability of the operation of the dryer and the optimization of operating conditions. With dry machine operation, wet material feeding, drying process in a completely sealed box, labor conditions are better, to avoid the leakage of dust. It is used for the drying of flake, strip and granular materials with good gas permeability. It is especially suitable for materials such as dehydrated vegetables and traditional Chinese medicine decoction pieces with high water content and high material temperature.

(4) Roller Scraper Dryer The drum scraper dryer is a continuous operation device for drying a liquid material or a strip material attached to the outer wall of the cylinder by means of a rotating cylinder by heat conduction. The liquid to be dried is flowed from the high level tank into the receiving tank of the drum dryer. The drying drum is driven by the transmission and rotates at a specified speed. The material is formed by a film coating device to form a film on the wall surface of the drum. The heating medium is continuously introduced into the cylinder, and the cylinder body is heated, and the moisture of the film is vaporized by the heat transfer of the cylinder wall, and then the material that meets the drying requirement is scraped off by a scraper, and is spirally conveyed into the storage tank for packaging.

The moisture removed by evaporation, depending on its nature, can be introduced into the corresponding treatment device through a closed hood; typically water vapor, which can be directly placed into the atmosphere by an exhaust pipe at the top of the hood. The machine is mainly used for the treatment of liquid materials, which can be heated and dried by steam, hot water or hot oil, or cooled by cold water. According to different material properties and process requirements, immersion, spray, and milled auxiliary feeding methods can be adopted.

(5) Double-cone rotary vacuum dryer The double-cone rotary vacuum dryer has a slightly olive-like shape with a cover at both ends, and two shafts are arranged in the middle to support the body. The body has a jacket to heat, and the body can be rotated when dry, so that the material and the wall are frequently replaced, which overcomes the disadvantage that the material in the vacuum oven mainly passes through the heating cylinder and has low thermal efficiency.

Rotary vacuum dryers have been widely used in fine chemicals and medicines, and are not suitable for materials with high viscosity or strong adhesion during the turning process. The equipment is mainly used for concentrating, mixing, drying and low-temperature drying materials (such as biochemical products) of powder, granular and fibrous materials in the pharmaceutical, chemical and food industries, and is more suitable for oxidizing, volatile and heat sensitive. Strongly irritating, toxic materials and drying of materials that do not allow damage to the crystals.

(6) Vacuum oven After evaporation, the evaporation temperature of the volatiles contained in the material evaporation can be reduced, which is suitable for drying various heat sensitive and easy oxide materials. This device is often a cylinder or other vacuum-operated outer casing. It is heated by electric heating or hot water or heat-conducting oil through a heating plate or a heating pipe, and is suitable for batch production in small batches. The oven is a general-purpose drying equipment with a wide application surface. It is a tray-type intermittent drying equipment and is used in pharmaceutical, chemical and food. Heat curing, drying and dehydration of materials and products in light industry, heavy industry and other industries. Such as raw materials, raw drugs, Chinese herbal medicine pieces, extracts, powders, granules, granules, water pills, packaging bottles, pigment dyes, dehydrated vegetables, dried fruits, sausages, plastic resins, electrical components, baking varnish and so on.

(7) Freeze dryer The freeze dryer is to freeze and freeze the feed liquid, and then depressurize the ice to sublimate the ice to obtain a dry material. Since the whole process is carried out below freezing point, it is often used for drying of heat sensitive articles. It is difficult to heat the frozen material under vacuum, and the condensed sublimated water vapor under reduced pressure requires a large refrigeration system, so the drying cost is large. The moisture in the highly heat sensitive material is frozen and will be maintained at a temperature below freezing below under high vacuum. The water is sublimed to separate from the material. The loss of active ingredients in the material is small, but the drying rate is low.

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Hollow paddle dryer correct operating procedures

Hollow paddle dryer is a horizontal agitating dryer based on heat conduction. Because the inner hollow agitating blade is shaped like a paddle, it is called a Hollow paddle dryer. The paddle dryer has been developed abroad for many years. This type of machine has developed two-axis and four-axis structures and multiple specifications in foreign countries. The paddle dryer was first developed by Germany. After that, the technology was introduced in Japan and improved. Two-axis and four-axis structures and more than ten specifications were developed. Since the heat required for drying the device is indirectly heated by heat conduction, the drying process requires only a small amount of gas to carry away the moisture, which greatly reduces the loss of heat that is carried away by the gas and improves the utilization of heat. Rate, strength drying Hollow paddle dryer is an energy-saving drying device. It can indirectly heat or cool the paste, granule, powder, and slurry materials, and can complete unit operations such as drying, cooling, heating, sterilization, reaction, and low-temperature calcination.

Hollow paddle dryer is widely used in activated sludge, sewage sludge, petrochemical sludge, paper sludge, printing and dyeing sludge, tannery sludge, electroplating sludge, municipal sewage sludge, oil sludge, chemical sludge , electro-ceramic sludge, river channel sediment silt, construction piling sludge, steel-making sludge, industrial metal pickling sludge, coal washing plant clean coal sludge, washed kaolin sludge, ceramics, marble polishing sludge, electronics factory line Sewage sludge, food plant activated sludge, mine beneficiation tailings, paper tailings/tail slag, leather/fur sludge, Chinese herbal medicine extract tailings, biological fermentation bacteria, and other high-humidity materials such as various sludges and various distiller’s grains .

First, the Hollow paddle dryer operating environment requirements

1. Check whether all parts of Hollow paddle dryer are installed properly. Does the lubricating oil added by the reducer meet the requirements of the reducer? Turn the motor fan impeller to check whether the blade shaft and the wall of the tube are not rubbed, the inlet is unblocked, and the inlet is clear. The material port is closed, etc.

2. Cover the motor impeller hood and start the motor to run dry. The blade rotation must meet the specified requirements. The blade runs without any abnormality, vibration and noise. During the gap operation, the feeding amount is limited to the submerged blade of the material, and the material valve is discharged after the specified time is reached.

3. The inlet valve and the condensate drain valve must be slowly opened under the rotation of the blade shaft. The steam should be slowly introduced into the jacket and the blade shaft for a period of 30 minutes or more. The pressure reducing valve and the safety valve must not be adjusted. Exceeding the rated pressure. The wet material can be evenly fed into the dryer under the condition that the steam pressure meets the specified requirements and the equipment is operating normally.

4. When the hollow paddle dryer is working, it is strictly forbidden to entrain the blocky hard material in the wet material to prevent the blocky hard object from getting stuck between the blade and the cylinder, damaging the blade or the cylinder, causing damage to the equipment. . During continuous operation, the amount of charge is controlled so that the host current does not exceed 70% of the rated current.

Second, the Hollow paddle dryer operation steps

1. Drain the condensate from the steam line and close the shutoff valve.

2. Turn on the air switch of the electric control cabinet (the corresponding display shows red light), and start the circulating fan of each heating chamber.

3. When the temperature in the drying chamber reaches 145 °C, set the switch of the speed regulating motor controller to the “on” position, then turn the speed control knob clockwise to make the pointer to the desired position. At the same time, adjust the tightness of the conveyor chain and start feeding the dryer.

4. Open the steam supply shut-off valve and heat the drying chamber. When the steam working pressure is 0.4~1.0Mpa, the excellent performance of the machine can be fully utilized.

5. Control the humidity in the drying chamber by adjusting the angle of the inlet and exhaust dampers to achieve the best dry condition of the material.

6. When the last batch of material leaves the dryer, the steam shut-off valve can be closed, and the fans will be turned off later (the corresponding green light is off).

7. When the last batch of material leaves the Hollow paddle dryer, turn off the main drive (the corresponding display green light is off), then turn the speed control knob counterclockwise to the zero position, and the controller switch is placed in the “off” position (the corresponding display is red) ).

Third, Hollow paddle dryer operation precautions

1. Check the gas source triple piece before starting the machine to drain the water and ensure sufficient oil level.

2. Do not allow overpressure or overload operation.

3. For different materials, care should be taken to control the feed rate to ensure smooth operation. In particular, it is not allowed to add large quantities of materials. Large pieces of metal or hard blocks such as stones are not allowed in the material to avoid damage to the equipment.

3. The material speed can be adjusted by using the discharge adjustment mechanism. After the commissioning personnel adjust, the equipment user must not change the position at will.

4. Observe whether the current is within the rated value of the motor. Otherwise, find the cause and solve it immediately.

5. The inlet valve and the condensate drain valve must be slowly opened under the rotation of the blade shaft. The steam should be slowly introduced into the jacket and the blade shaft. The time is controlled for more than 30 minutes. The pressure reducing valve and the safety valve must not be adjusted. Exceeding the rated pressure. The wet material can be evenly fed into the dryer under the condition that the steam pressure meets the specified requirements and the equipment is operating normally.

6. Open the sight glass cover on the bearing body and observe if there is any leak in the seals.

7. The gear meshing parts and chain should be greased in time, and pay attention to dust and cover dust cover.

8. After using the equipment for one week, drain the lubricating oil in the reducer and replace the new oil of the same model.

9. When parking, try to drain the materials in the machine, stop the steam inlet and drain the condensate, close all the valves, and stop the rotation of the blade shaft after all the equipment is cooled to room temperature (to prevent the blade shaft from bending and deforming) ).

10. When the gap is operated, the feeding amount is limited to the submerged blade of the material. After the specified time is reached, the material valve is discharged.

11. During continuous operation, control the amount of material to be fed so that the maximum current of the main unit does not exceed 70% of the rated current.

12. It is strictly forbidden to entrain the blocky hard material in the wet material to prevent the blocky hard object from getting stuck between the blade and the cylinder body, damaging the blade or the cylinder body, causing the equipment to be damaged and leaking.

13. The temperature of the intended bearing body should not be higher than 70 degrees Celsius, and high-quality grease can be added at the right time. The amount of cooling water to be adjusted for the bearing body and the shaft seal packing with a cooling device.

Although the Hollow paddle dryer is a relatively efficient and energy-saving dryer, if it is not noticed during the operation, it will cause some equipment failures and operational errors. Over time, it will affect the service life of the Hollow paddle dryer. It is not enough to ensure that the service life of the paddle dryer is based on the correct operating procedures. Some daily maintenance techniques are needed to achieve the desired results, such as the following:

1. After the production is completed, if it is not used for a long time, it should be cleaned, especially the door seals are cleaned to prevent aging. Close the door tightly, do not tell the door locking device is too tight to prevent deformation, and cut off the power and water.

2. If it is not used for a long time, it should be cleaned regularly. Please do not use liquid with acid and alkali strength to clean it. Clean it with water. After cleaning, pay attention to dry the water.

3. For the water ring vacuum pump, it is necessary to replace the circulating water every day. If it is to be used for a long time, it must be exhausted after the use of the vacuum pump, and the vacuum pump should be pumped every day when the temperature is below zero in winter. The body water should be drained. Before the next use, please pay attention to whether the vacuum pump is rusted. If the rust is dead, remove the vacuum pump motor back cover and screw the motor shaft with a tool.

4. For the rotary vane vacuum pump, the vacuum pump oil should be replaced regularly, once or twice a month. If it is to be used for a long time, the vacuum pump oil must be drained after one use, and the new vacuum pump oil should be injected before the next use.

5. the common parts expired need to be replaced, such as vacuum table damage, need to replace the new vacuum table, the seal is aging due to age, should be purchased from the manufacturer, each valve will cause the PTFE seal in the valve after a long time Wear and tear, so that the vacuum can not be pumped to a reasonable value, the new air valve should be replaced immediately.

6. If the equipment fails during normal use, it should immediately respond to the manufacturer and should not be disassembled by itself to avoid serious damage.

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