How to choose drying equipment for light calcium carbonate?

In the production process of light calcium carbonate, drying is one of the main energy-consuming units, and it is also an important process that affects the final quality of the product, such as impurities such as black spots, pH, and sedimentation volume. Therefore, it is especially critical and urgent to choose drying equipment with low energy consumption, high productivity and green environmental protection.

1, light calcium carbonate drying characteristics

Drying of light calcium carbonate generally goes through two stages:

(1) First, the concentrated calcium carbonate slurry is mechanically dehydrated to form a filter cake having a water content of about 30%, and then the filter cake is mechanically broken into uniform granules;

(2) The granular material enters the dryer, and the drying process is completed after dispersion, heat transfer and mass transfer.

The characteristic of calcium carbonate filter cake is that it is a paste-like material, and its moisture is mainly composed of osmotic water, and the viscosity of the material is large and the dispersion is poor.

It is very important to crush and disperse in the drying process, and the best way to remove the infiltrated water is to directly transfer heat to the material. Therefore, the drying of the light calcium carbonate should be carried out by a dryer which is advantageous for material dispersion and heat transfer area.

2, light calcium carbonate commonly used drying equipment

Drying equipment commonly used in light calcium carbonate enterprises includes drum dryers, rotary tube dryers, mesh belt dryers, tray dryers, paddle dryers, and rotary flash drying.

3. How to choose a light calcium carbonate drying equipment?

At present, the drying equipment used in China’s calcium carbonate industry is mostly used in other industries, and these equipments are not designed for the drying of light calcium carbonate, and often need to be customized or modified according to production requirements.

For light calcium carbonate producers, only by continuously improving the level of drying technology and minimizing the cost of drying can they be invincible in the fierce market competition environment. Therefore, light calcium carbonate enterprises choose drying equipment. The following points should be followed:

(1) to ensure the product quality requirements, uniform drying quality;
(2) Adapt to the state of the material, such as block, slurry or powder, granular, etc.;
(3) The drying rate is high and the required production capacity is achieved;
(4) Low energy consumption, high thermal efficiency, and stability;
(5) It has little environmental pollution and a good working environment;
(6) Low investment, safe and reliable operation;
(7) Adapting to the thermal deterioration of the material, that is, considering the heat sensitivity of the material, which determines the upper limit of the temperature of the material to be dried, is an important condition for selecting the drying equipment and the heat source;
(8) According to the process, the performance requirements of the drying equipment are proposed and determined, and the equipment manufacturer provides equipment that can fully meet the process requirements.

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Development of double stream high mixing technology

In recent years, with the rapid development of industrial and agricultural production, the demand for drying equipment has become larger and larger, the structure and performance of the dryer have been significantly improved, the quality has been continuously improved, and the overall level of drying equipment has been continuously improved. The progress is mainly manifested in the following aspects: the control system is equipped, the automatic and semi-automatic control systems are widely used, the labor intensity is reduced, the product quality is stable; the application of computer technology, most of the large-scale systems use computer technology to collect system parameters, Processing and control to optimize the operating conditions of the system; user-friendly design, taking into account the operator’s habits and convenience during maintenance; safe design, safety alarm and danger elimination function in the system, especially The drying of flammable and explosive materials should take this into consideration; the ancillary equipment, the auxiliary equipment in the system also tends to be reasonable, and the matching relationship between heating, feeding, gas-solid separation, product packaging equipment and the main machine is optimized.

In the feed unit of the actual application, not only the processing amount is relatively limited, but also the energy consumption is large. In order to solve this problem, our company has initiated the research and development of the two-stream high-mixing technology. Under the premise of stable feeding, the company realizes a large amount of processing and avoids the phenomenon of winding the shaft and reduces the power and energy consumption of the equipment.

Development of dual-stream high-mixing technology:

1. The feeding technology of double-flow high-level material mixing has been developed, which makes the sludge and other materials greatly improve the drying efficiency in the drying process;

2. A plurality of feeding ports are uniformly distributed on the upper part of the device, uniformly feeding, and the viscous sludge is directly added to the base material having a lower water content; that is, the wet material is uniformly added to each drying unit layer in the axial direction by the upper cloth distributing mechanism. The structurally hot powdery dry material is rapidly mixed with the hot dry material in the casing under the stirring action of the hot shaft blade;

3. Reduce the spindle torque, sludge and other viscous materials run more smoothly in the drying process, and the structure is more compact than the traditional dryer, and the auxiliary device is less, the heat loss is also reduced, so that the motor can save 30% than the traditional dryer consumption. Energy saving requirements;
4. The wet material is mixed with the hot dry material to make the high temperature dry material particles coated with a layer of wet material, increase the heat exchange area, accelerate the heat transfer of the wet material, thereby increasing the material drying rate; The state of the material in the body is always in a flowing state, so that the state of the material in the drying device is always in a mixed state, avoiding the work of the material in the high viscosity water interval in the casing, and avoiding the winding of the wet material;

5. Ensure that the wet material is uniformly added to the drying equipment along the axial direction. At the same time, by adjusting the feeding speed to control the dry material and the wet material to maintain a certain mixing ratio, the system can be prevented from working due to the occurrence of the winding of the device;

6. New technology of double-flow high-mixing material improves the heat and mass transfer in the drying process and accelerates the drying rate. For the viscous characteristics of sludge, the high-mixing technology department can effectively avoid the phenomenon of sludge-winding. The traditional feeding technology is equipment. One end feeds and the other end discharges, and the high level mixing technology adopts a plurality of feed ports uniformly distributed over the entire equipment, uniformly feeding, and adding the viscous sludge directly to the lower water base. After mixing, it can effectively avoid the contact of the viscous sludge directly with the blade shaft of the equipment, thereby avoiding the occurrence of the entanglement of the shaft;

7. When the wet material is a water-containing powder material and a paste-like material, the cloth mechanism adopts a spiral feeding method, so that the wet material is evenly added on the dry material in the rectangular shell, and the two hollow structures of each drying unit layer structure are rotated. The vane shaft is heated by steam or heat transfer oil to heat and dry the wet material in the shell to evaporate the material. At the same time, the hollow vane shaft stirs and heats the mixed material through the blades on the hollow vane. Heat transfer between the heat transfer surfaces of the blades;

8. When the wet material is liquid material, the cloth mechanism adopts the sports car feeding mode to drive the feeding nozzle through the sports car that reciprocates axially along the rotary axis, and the liquid material conveyed from the conveying pipe is evenly added to the dry material in the rectangular casing. The two hollow vane shafts of each drying unit layer structure are ventilated with steam or heat transfer oil.

The material in the casing is heated and dried by heat conduction to evaporate the material; at the same time, the hollow blade shaft stirs and heats the mixed state through the blades thereon, so that the material continuously exchanges heat with the heat transfer surface of the blade. Through the upgrade of these technical aspects, the problem of small processing capacity and large energy consumption in the feeding process of the equipment is effectively solved. If you need more questions about the paddle dryer, please feel free to leave us a message on the website and we will respond positively.

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The difference between drying equipment and drying equipment

When we want to dehydrate a product, we will think of drying equipment or drying equipment. We will look for information about drying equipment and drying equipment. Because of the special information about this type of product, we often have Mix the drying equipment with the drying equipment. I don’t know how to distinguish between drying equipment and drying equipment.

For example, we say that food drying equipment can generally be understood as a device that can dry food. It is concerned with the result of “drying”, not the drying process, such as microwave dryer, which emphasizes the result of drying with microwave instead of the process. Therefore, drying equipment can be understood in a broad sense as any equipment that can “dry” the product, including “low temperature drying equipment”, “high temperature drying equipment”, “air drying equipment”, “dewatering equipment”, “drying equipment”, “freeze drying” Equipment”, in any case, any method, any method, which can dry the product can be called drying equipment

What is the difference between drying equipment? It emphasizes “drying”, which is a dry method or process, that is, placing the product in a certain temperature environment, allowing it to “bake” the ambient temperature and obtain The result of drying. For example, heat pump drying equipment, which emphasizes the use of heat pump to generate temperature to dry the product, it emphasizes the process of “drying”.

Therefore, drying is a method of obtaining a drying result, and the drying equipment is only a type of drying equipment that uses a drying method for drying. It can be said that the drying equipment includes drying equipment, and the drying equipment is only one type of drying equipment commonly used in many drying equipments, and they are included and affiliated.

Drying equipment on the market can generally be divided into five broad categories from dry form:

First, static drying equipment:
Hot air circulation oven (room), high temperature sterilization oven, circular vacuum dryer, square vacuum dryer.

Second, continuous drying equipment:
Belt dryer, dehydrated vegetable dryer, roller scraper wafer dryer, rotary drum dryer, disc continuous dryer, vacuum tray dryer.

Third, stirring type drying equipment:
Vacuum dryer, double cone rotary vacuum dryer, horizontal vacuum ribbon dryer, LHG vertical vacuum ribbon dryer, openable vacuum mixing dryer, hollow blade dryer, high efficiency boiling dryer.

Fourth, fluidized dryer:
Rotary flash dryer, spiral vibration dryer, horizontal boiling dryer, pulse air dryer, enhanced airflow dryer, linear vibration fluidized bed dryer.（You can also learn about the specific information of the relevant partner Vibrating screen manufacturer.）

Five, spray dryer:
High-speed centrifugal spray dryer, Chinese medicine extract centrifugal spray dryer, pressure spray dryer, pressure spray granulation dryer.

In addition, according to the difference of the heat source of the drying equipment, the difference of the drying process principle and the application industry, there are many other different classifications. With the continuous improvement of production processes in various specific fields, the selection and application of drying equipment has become more and more rational; a variety of combined drying equipment (systems) have emerged, and drying equipment has become more energy-saving and environmentally friendly.

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Cooling, use of feed drying equipment

The processing equipment is for the production process and is the specific implementer of the reasonable production process. With the continuous improvement and improvement of the feed processing technology level, the performance requirements of the feed processing equipment are also more stringent. Here, not only the traditional host equipment, such as pulverizers, mixers and molding equipment, but also such as dryers, cooling, etc. Auxiliary equipment such as a stable, post-curing device, sprayer. At present, relatively reasonable auxiliary processing equipment is used in the more reasonable and complete feed processing process, and these equipments have a non-negligible influence on the finished feed products.

1. Cooling equipment in feed processing

In China’s feed production enterprises, most of the feed processing processes use granulators to produce pellet feed. The pellets just produced from the granulator have a temperature of about 85 ° C and a moisture content of 13% to 17%. At this time, the feed pellets are brittle, and should be cooled and dehydrated in time to reduce the temperature to near room temperature (about above room temperature). 3 ° C ~ 5 ° C), the water is reduced to 12% ~ 13% (that is, safe storage of water), making it easy to break processing and storage. This process is usually performed using a cooler.

At present, there are three main types of coolers used by feed enterprises: vertical, horizontal and countercurrent. The counterflow cooler has quickly replaced the other two types of coolers as the current mainstream products due to its high degree of automation, small floor space, small suction volume and low power consumption. It is widely used by feed enterprises.

The counter-flow cooler uses the principle of counter-current cooling to cool the high-temperature and high-humidity pellet feed. The equipment is mainly composed of a closed-air feeder, a bulker, a cooling bin, and a discharge device. According to the different structural forms of the unloading device, there are many derivative series. The two unloading devices with mature technology are the sliding gate discharging mechanism and the flap discharging mechanism (also called “rotating valve type discharging mechanism”). Among the counterflow coolers produced by the Shepherd Group, the SKLN series coolers use a sliding gate discharge mechanism, and the SLNF series coolers use a flap discharge mechanism.

During use, the counterflow cooler should consider the following aspects in order to facilitate the operation of the equipment in an efficient and economical state.

1.1 Airflow status
For counterflow coolers, the most important airflow parameters are: air volume, wind pressure and wind speed.

Normally, SKLN series and SLNF series coolers are equipped with fans with a reference air volume of φ12 mm.

When cooling, it is important to determine a reasonable range of wind speeds. Typically, 1.8m/sec is a generally accepted indicator. At the same time, the wind speed in the suction pipe should be 13 to 16 m/sec. In the conventional sliding grid counterflow cooler, excessive wind speed causes agglomeration, arching and uneven discharge, which also causes the fluidized bed to “fluidize”, resulting in different retention times due to different materials retention time. . In addition, controlling the wind speed can effectively avoid creating a “wind tunnel” on the bed, preventing the airflow from short-circuiting and affecting the cooling effect.

Normally, the thickness of the SKLN series and SLNF series coolers is between 0.7m and 1.1m, and the recommended wind pressure should be ≥200mmH2O.

1.2 Counterflow cooler discharge opening area

By considering the cooling air volume of the unit pellet feed and the maximum wind speed, the maximum output of a certain type of counterflow cooler can be determined. Therefore, in order to obtain higher production, the cooling air volume should be increased, and at the same time, the area of ​​the discharge system should be increased accordingly. The discharge ports of the SKLN series and SLNF series coolers are square or rectangular. This design has a better floor space utilization than the circular shape counterflow cooler of the same size, and the production capacity is increased by 28%. This is why the SKLN series and SLNF series coolers have greater cooling capacity.

1.3 Prevent arching and agglomeration

The higher the output, the greater the amount of air required for cooling operations. For counter-flow coolers, this means an increase in the probability of arching and agglomeration. If a counterflow cooler is to be obtained with a larger output, the unloading device must meet certain requirements, ie the large air volume required to increase the output and Under the premise of higher wind pressure, it can still discharge evenly and reliably. Smaller size grate and vane counterflow coolers are less distinct in this respect, but have a certain advantage as an improved flap counterflow cooler when the cooling output is large or the easy to pellet pellet feed is processed. At the time of discharging, one end of the flap is lifted up to break the arch, thereby effectively preventing arching and agglomeration which may occur in the discharge mechanism of the sliding gate.

1.4 Some reference suggestions

According to some data, the higher the moisture content of the feed pellets, the faster the water evaporation rate and the better the cooling effect. Analysis of the reason, it is not difficult to see that the evaporation of water requires heat, and it is the feed pellet itself that provides heat in the cooler, which is what cooling treatment hopes. Therefore, within the allowable range, consideration should be given to appropriately increasing the feed moisture, which is beneficial to increase the cooler output.

When the counter-flow cooler is started and emptied, there may be a problem that the pressure drop becomes small due to the thinner thickness of the material layer in the cooling chamber, resulting in a larger air volume of the fan. Feed pellets are drawn into the duct and a “wind tunnel” is created on the bed. Is it possible to explore the setting of an automatic control damper to solve this problem.

2. Drying equipment in feed processing

In recent years, the development of China’s feed industry has shown a new trend, that is, the extrusion technology has been widely accepted by feed manufacturers due to its unique superiority. After entering the feed processing industry, the large-scale puffing equipment represented by the shepherd “Century Dragon” MY165 extrusion extruder has quickly become one of the main models for producing high-grade puffed aquatic feed.

Under normal circumstances, the moisture content of the extruded product is relatively high. Taking the floating fish feed as an example, the moisture content after the mold is usually 21% to 24%, and the safe storage moisture of the expanded aquatic feed is generally controlled to be about 10%. It is impossible to meet the need for water removal by ordinary cooling equipment. This requires a special drying treatment section and special drying equipment in the production process.

Most horizontal dryers have a single or multi-layer conveyor belt (which can also be a perforated steel track) to support the movement of material in the drying chamber. The hot air passes vertically through the layer, where heat and moisture are exchanged with the material on the conveyor belt and subsequently discharged through a dedicated passage. This is the general working principle of a horizontal dryer. As the material moves with the conveyor belt in the drying chamber, its movement speed is slower, the path is longer, the drying time is also increased compared with the vertical dryer, and all materials have approximately the same external drying conditions, so the horizontal dryer is in one In the drying process, it is superior to the vertical dryer in terms of precipitation amplitude or product moisture uniformity, which is determined by the drying principle and mechanical structure of the horizontal dryer.

Drying is a relatively complicated process and is subject to many factors, such as drying time, hot air temperature, hot air volume, material properties and geometry of the material components, etc., which will affect the final drying effect, which is reflected in the product moisture content. Two main indicators of water unevenness. An excellent and stable drying system not only refers to a powerful dryer, but also includes parts such as auxiliary machinery, thermal systems, air duct systems, electrical control systems. Good drying results are the result of the combined action of all components in the drying system and should be considered in the following aspects during selection and operation:

2.1 Spreader

For the horizontal dryer, the advantages and disadvantages of the spreader directly affect the uniformity of the product moisture, which is an important part of the drying system.

The spreader spreads the material evenly on the conveyor belt, so that the air volume at each point on the conveyor belt is approximately the same, which is one of the prerequisites for uniform moisture of the product. The spreader can be subordinate to the dryer, or it can be independently formed into a single device in many forms, such as an oscillating type, a horizontal cymbal, an oscillating conveyor belt, and the like. The user can select the appropriate form according to the actual needs, and does not damage the appearance of the material is another principle other than the spreading effect.

At present, the more mature one is the oscillating spreader, which has simple mechanical structure, reliable transmission, adjustable oscillation frequency and amplitude, and good spreading effect, and is suitable for most aquatic products. This spreader is used in the SKGD series belt circulation dryer.

2.2 System and wind road

Consideration should be given to providing sufficient and stable heat to the dryer, otherwise the stability of the dryer operation cannot be guaranteed. The feed dryer can be selected from steam, heat transfer oil or gas as a heat source, wherein the gas efficiency is high.
Since some aspects of the feed processing process require steam intervention, such as granulation, puffing, etc., in general, steam should be the preferred source of heat for the dryer, which can reduce the initial investment in the plant and save on daily management costs.

The heat exchanger is the core component of the heating system. From the practical application effect, the steam heat exchanger of the steel-aluminum composite finned tube has better performance, and the finned tube is not easily deformed and accumulated.

Conventional horizontal dryers use a larger heat exchanger to deliver hot air to each drying chamber through multiple branch air paths. The problem brought by this method is that the air volume distribution of each drying room is not easy to control, and the branch air path needs to be insulated, and takes up a large space outside the dryer, and the structure is relatively complicated. The SKGD series belt-type circulation dryer solves the above problems by using separate heating and drying channels in each drying chamber. At the same time, the hot air recycling makes the energy consumption of the SKGD series dryer greatly reduced, the hourly processing capacity is 3.5 tons (φ3mm floating puffed fish), and the steam consumption from 24% to 10% is about 1.5t/h.

2.3 Control system

The automatic control of the feed drying system is difficult to achieve, because there are many factors affecting the drying process, and there are many links that need to be controlled. The cost of the entire control system is expensive, which is uneconomical for feed drying. Then the more realistic method should be to automatically control a certain important parameter and manually adjust other parameters. On the SKGD series dryers, the drying temperature is automatically adjusted, while the air volume and drying time are manually adjusted. The automatic control of the temperature ensures that the dryer can still operate in a relatively stable temperature range when there is fluctuations in the steam.

2.4 Processed materials

The composition and physical properties of the material also have a large effect on the final drying effect:
1 If the feed formula contains a high proportion of oils and fats, it is unfavorable to dry.
2 When the feed particles are relatively dense, it is not conducive to the diffusion of moisture inside the particles along the capillary to the surface layer of the particles.
3 When the feed particle size is large, a longer drying time is required.
4 All feed particle sizes should not be too different, otherwise it is difficult to obtain good indicators of dry unevenness.
5 Under normal circumstances, sinking feed is more difficult to dry than floating feed.

2.5 Some reference suggestions

1 Drying requires heat. Within the allowable limits, higher temperatures are beneficial to increase the efficiency of the dryer. However, under high temperature conditions, it will affect the nutritional value of the feed, such as non-enzymatic browning. Usually the feed drying temperature should not exceed 120 °C. It is also conceivable to let the feed stay in the high temperature (100 ° C ~ 200 ° C) environment for a few minutes, so that the particles quickly heat up, after which the hot air temperature should be reduced to complete the remaining drying operations.

2 should avoid the rapid loss of water in the surface layer of the particles in the early stage of drying, forming a “water seal”, destroying the capillary layer connecting the surface layer of the particles and the inside, preventing the particle core moisture from eventually spreading outward.

3 The drying process of any material takes a certain amount of time. In a drying process, the operating parameters should not be changed frequently and should be left to the dryer for a certain reaction time. Only in this way can the optimal operating parameters of a certain material be obtained.

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Paddle dryer design and development

First, Paddle dryer design

The RD-Paddle dryer design process consists of nine parts, namely:

1. Sub-cylinder 2. Buffering silo 3. Cloth spiral 4. Drying main unit of RD (two stages) 5. Discharge spiral 6. Wet dust collector 7. Condenser 8. Induced draft fan 9. Cooling tower

Paddle dryer design picture

 

You can also browse more about the working principle and equipment classification of the paddle dryer.

Second, the design and development of multi-effect drying method for the purpose of energy saving

The RD multi-effect drying method is a dry energy-saving process developed by Luoyang Ruidao Drying Engineering Co., Ltd. according to the characteristics of the conduction heating dryer and the application properties of the steam heat source. The dry and volatilized secondary steam is subjected to heat-filtering, dust-removing, and becomes a heat source that can be used for drying, thereby achieving energy-saving purposes. RD multi-effect drying method together with RD multi-stage multi-stage multi-effect drying device, RD liquid drying machine and RD continuous vacuum drying device form a complete conduction heating drying system.

Third, increase production and ensure the stability of feeding, we have developed the feeding system

The control system is equipped with automatic and semi-automatic control systems, which makes the labor intensity lower and the product quality stable. The application of computer technology, most of the large-scale systems use computer technology to collect the system parameters. In practical applications, the dryer passes. When the screw conveyor realizes feeding, the screw shaft of the screw conveyor adopts a double support structure to pass through the dryer, that is, the transmission end of the screw shaft is supported by two sets of bearings, and the tail end of the screw shaft is provided with a bearing support. As far as the feeding unit is concerned, the satisfactory level of feeding has not been achieved, and the feed stability is not good enough. The company specializes in the comprehensive utilization technology and drying equipment for the harmless, reduced and resourced industrial waste. And production, in response to the above problems, the project is currently developing a stable feed system.

Development results of the paddle dryer loading system

  • We have developed a stable and reliable feeding system;
  • The original shaftless screw conveyor is designed with a reverse thrust spiral according to the characteristics of the material;
  • The vibrating rod and the power device are added in the feeding system, which not only ensures the smooth operation of the system feeding module, but also promotes the stability of the feeding system and increases the processing amount;
  • Developed a liquid feeding device, using static painting technology and method, embedded in the PLC solenoid valve control module to achieve automatic feeding;
  • The sludge and other materials are evenly added by the feeding spiral, and the stirring process in the hollow blade shaft is carried out for the next process;
  • The feeding amount and the host speed are controlled by a microcomputer system, and there is a current voltage alarm device to further ensure the stability of its work.

Dryer main blade
Fourth, the development of sludge drying system – Application to Municipal Sewage Sludge

In the process of urbanization development, the sewage treatment rate has been improved, and the sludge output of sewage treatment appendages has greatly increased. How to treat and dispose of these sludges to make them harmless and utilize them is a big problem. For a long time, due to the tendency of “heavy water and light mud” in the sewage treatment sector in China, the problem of sanitization and harmless treatment of sludge has not been paid attention to and solved. At present, the municipal sludge production in major cities in China is counting every day. More than 100 tons, the output of the traditional conduction heating dryer can not meet the needs. Municipal sludge and industrial sludge as waste have low added value, and according to their high water content and large processing capacity, the energy consumption of the drying process is very important and is a key issue in sludge treatment.

In response to the above problems and the needs of the development of the industry, the company is currently working on a technical solution for large-scale drying systems for sludge treatment. The project plans to adopt modular and standardized design to realize multi-layer multi-level structural innovation, and develop a large-scale conduction heating multi-layer multi-stage dryer, which greatly increases the heat transfer area of ​​the traditional conduction heating dryer, thus greatly improving the The single machine throughput of the conduction heating dryer.

Through years of hard work and development, we have achieved the following results:

1. Developed a multi-layer multi-stage sludge drying system for municipal sludge and industrial sludge to dry and treat solid waste such as municipal sludge, industrial sludge and pharmaceutical waste;

2. Adopt modular and standardized design technology to develop multi-layer multi-level structure of multiple drying unit layers (and) to minimize infrastructure investment and floor space. Applying the principle of multi-effect evaporation, the atmospheric pressure evaporated from the sludge is continuously recycled by the supercharging technology as a heat source;

3. Establish a multi-level multi-level intelligent control model based on PLC technology with the target function value of treatment volume and sludge product moisture content, with each drying unit layer temperature, feed amount and spindle speed as parameters. The heating area of ​​the single unit is obviously improved, and the control of the whole set of equipment is more precise and intelligent;

4. Incorporate high-level mixing technology to avoid the winding of the viscous material at the beginning of the operation, greatly reducing the power consumption of the motor and achieving energy-saving purposes;

5, using two-stage exhaust gas treatment process, the entire system is free of dust, odor emissions, no secondary pollution problems;

6. The fillet weld of the blade adopts the wear-resistant form, that is, the wear-resistant blade weld design is adopted to reduce the wear of the sludge on the blade, and the service life of the whole machine can be improved by more than two years;

7. Using CNC technology to realize automatic cutting of the blade, improve the utilization rate of the material while improving the precision of the sludge dryer, and improve the production efficiency;

8. When manufacturing heavy-duty heat-conducting shafts, due to the large volume and weight of the main shaft, a lot of manpower and time is wasted to rotate and hoist during manufacturing and processing. Now, a new type of fixture is invented – the tire is transferred, and the heavy shaft is stuck on the tire. By welding the blade, the processing position can be easily controlled, the productivity is improved, and the labor intensity is reduced;

9. Adopt carbon dioxide protection welding and automatic welding mold to make the welding points more solid and stable, reduce leakage points and improve equipment life;

10. The hollow blade of the main shaft is creatively designed into four symmetrical structures, which effectively reduces the running resistance of the main shaft and reduces the frequency of the variable frequency motor, thereby reducing the power consumption of the spindle load by 20% and achieving energy saving.

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Development of hot shaft mixing drying process

Project project

At present, the drying of conventional water-containing powder materials mostly uses an existing drum dryer. This kind of equipment not only consumes a lot of energy, but also has a large floor space, and excessive exhaust emissions are likely to cause dust to pollute the environment. For the drying of paste materials, drying equipment such as a drum dryer, a rotary flash dryer, and a hollow blade dryer are currently used. The drum dryer and the rotary flash dryer are easy to cause dust to pollute the environment due to the use of hot air drying, high energy consumption and large exhaust gas displacement. The hollow blade dryer is a conduction heating dryer, which has low energy consumption and a small amount of exhaust gas treatment, but is limited by its structure and operation mechanism, and the treatment amount is small. For the drying of liquid materials, spray dryers are currently used; however, due to the excessive energy consumption of spray dryers, the operating costs are high, especially in environmental protection industries.

In order to solve the above problems, the company is currently working on the hot shaft mixing drying process and related equipment research.

Project achievement

1. Successfully developed the hot shaft mixing drying process and equipment, and thoroughly mixed and dried with the pre-laying dry material in the dry layer to greatly improve the heat exchange area, improve the drying efficiency, and improve the heat of the wet material. Mass transfer, thereby increasing the material drying rate; and avoiding the occurrence of wrap-around of the added wet material, thereby greatly reducing the power of the drying shaft device;

2. The hot shaft mixing and drying device comprises a bottom of a plurality of superimposed drying unit layers and a drying bin, and each drying unit layer structure is composed of two cloths arranged in a rectangular casing and a hollow blade forming a pair of fan blades. The shaft and the feeding system are composed, and the feeding system is arranged above the two parallel hollow blade shafts;

3. The feeding system comprises: a spiral feeding system for drying the aqueous powdery material and the paste material, the two parallel hollow blade shafts and the upper spiral feeding system constitute a drying unit layer of the spiral feeding system; or the sports car for the liquid material drying The system, two parallel hollow vane shafts and the upper sports car feeding system constitute a drying unit layer of the sports car feeding system;

4. The spiral feeding system drying unit layer is composed of two hollow vane shafts and a spiral feeding mechanism. One pair of fan-shaped vanes on the two axially parallel hollow vane shafts cross each other, and the spiral feeding mechanism above the two hollow vane shafts is composed of The spiral cloth device and the feeding port of the wet material are composed, the feeding port of the wet material is located above one end of the spiral cloth device; the outer end of the hollow blade shaft is connected with the stirring motor through the transmission mechanism, and the inner hole of the hollow blade shaft is connected with the steam source; The cloth device is composed of one end of the cloth spiral shaft and the cloth motor, and the cloth spiral shaft is located at a center position above the two hollow blade shafts;

5. The drying unit layer of the sports car feeding system consists of two hollow blade shafts in a rectangular casing and a reciprocating sports car feeding device. One pair of fan blades on the two axially parallel hollow blade axes cross each other, and two hollow blade shafts The top of the vehicle is provided with a sports car feeding device; the sports car feeding device is composed of a feeding sports car, a sports car chute and a feeding pipe, and a feeding nozzle is arranged on the feeding pipe; a volatilizing steam discharge port is arranged above one side of the rectangular casing; the drying bin is a rectangular parallelepiped structure a discharge port is arranged above the drying bin to communicate with the bottom of the rectangular casing;

6. The whole system adopts a drying device composed of a single or a plurality of drying unit layers superposed to realize mixing of the powdery dry material and the wet material of the drying operation, and drying the wet material by the blade stirring of the hot shaft and the heating of the hot shaft, The steps at work are as follows:
1) There are powdery dry materials in the shell at the beginning of the drying operation and during the normal drying process; 2) The wet material is uniformly added to the drying layer of the hot powdery dry material in the axial direction by the upper fabric mechanism. Medium, in the hot shaft blade agitation, quickly mix with the hot dry material in the housing;

3) The wet material is mixed with the hot dry material to make the high temperature dry material particles coated with a layer of wet material, increase the heat exchange area, accelerate the heat transfer of the wet material, thereby increasing the material drying rate; The state of the material in the body is always in a flowing state, so that the state of the material in the drying device is always in a mixed state, avoiding the work of the material in the high-viscosity water interval in the casing, and avoiding the winding of the wet material;

7. When the wet material is a water-containing powder material and a paste-like material, the cloth mechanism adopts a spiral feeding method, so that the wet material is evenly added on the dry material in the rectangular shell, and the two hollow structures of each drying unit layer structure are rotated. The vane shaft is heated by steam or heat transfer oil to heat and dry the wet material in the shell to evaporate the material. At the same time, the hollow vane shaft stirs and heats the mixed material through the blades thereon to make the material continuously Heat transfer on the heat transfer surface of the blade;

8. When the wet material is liquid material, the cloth mechanism adopts the sports car feeding mode to drive the feeding nozzle through the sports car that reciprocates axially along the rotary axis, and the liquid material conveyed from the conveying pipe is evenly added to the dry material in the rectangular casing. The two hollow vane shafts of each drying unit layer structure are heated by steam or heat transfer oil to heat and dry the materials in the shell to evaporate the material; and the hollow vane shaft is mixed by the vane pairs thereon. The material in the state is stirred and heated to continuously exchange heat with the heat transfer surface of the blade;

9. During drying, as the wet material is continuously added, the dry dry material is discharged from the discharge port, and the volatile gas is discharged from the side exhaust outlet;

The technical solutions developed by this project have the following advantages:

The drying efficiency is greatly improved by thoroughly mixing and drying the pre-packed dry material in the dried layer with the newly added material. That is, the microscopic high-temperature dry material particles are coated with a layer of wet material, which greatly improves the heat exchange area, improves the heat mass transfer of the wet material, thereby improving the material drying rate; macroscopically, the material state in the casing is always in a flowable state. The state of the material in the drying device is always the state of mixing, avoiding the high-viscosity water content of the material, avoiding the situation that the wet material of the equipment is wrapped around the shaft, thereby reducing the power of the shaft of the equipment;

1) Conducive to large-scale production and manufacturing of drying equipment;
2) reduce the required floor space of the drying equipment;
3) Because the mixing drying process is adopted, the material is prevented from being wound around the shaft, thereby greatly reducing the driving power;
4) The mixing drying process improves the heat exchange efficiency of the material and reduces the operating cost;
5) The drying process of the liquid material is greatly shortened, and the auxiliary equipment in the drying process of the traditional liquid material is reduced;
6) The process combination is convenient, not only can a combination of processes such as series and parallel can be performed, and each dry layer can also work alone.

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RD-Rotary dryer working principle and maintenance

working principle

1. The belt conveyor or the bucket elevator is sent to the hopper, and then the feeder of the hopper enters the feeding end through the feeding pipeline.

2. The slope of the feeding pipe should be larger than the natural inclination of the material so that the material can flow smoothly into the tumble dryer.

3. The drum dryer cylinder is a rotating cylinder that is slightly inclined with respect to the horizontal line. The higher material end is added, the heat carrier enters from the lower end, and is in countercurrent contact with the material, and the heat carrier and the material enter the cylinder together.

4. As the rotating material of the cylinder is moved by gravity to the lower end. The wet material is directly or indirectly obtained during the forward movement of the wet material, so that the wet material is dried, and then sent out at the discharge end by a belt conveyor or a screw conveyor.

5. The inner wall of the drum dryer cylinder is equipped with a copy board. Its function is to copy and sprinkle the material, so that the contact surface of the material and the air flow is increased to increase the drying rate and promote the advancement of the material.

6. After the heat carrier passes through the dryer, the cyclone dust collector is generally required to collect the materials contained in the gas (the heat carrier is generally hot air, flue gas, etc.).

If you want to further reduce the dust content of the exhaust gas, you should also discharge it through a bag filter or a wet dust collector.

Use and maintenance

1. Dry the butter at the gear before starting the machine;

2, wipe the surface of the belt for 7 days to dry the butter;

3. The bearing housing is fired every three months or replaced with new dry butter;

4. The gear oil must be added once before the reducer is used, and replaced every four months thereafter.

Precautions

The dryer is used as a drying material for drying equipment. Usually, heat transfer is required through high temperature to reduce the water content in the material. However, because the high temperature also causes the safety hazard in the dryer, the main safety hazards that the drying equipment needs to pay attention to, and at the same time have a certain understanding of the hazards caused by the safety hazard of the dryer, hoping to help everyone better use the drying Dry machine!

Security Hidden 1: Host Installation

Under normal circumstances, the dryer adopts a low-fire installation with a high fire end. This installation method will largely lead to the speed at which the material to be dried flows to the far fire end. If the storage capacity of the drying material is low, a large amount of heat will be paid, and the utilization efficiency of the dryer drum space is affected.

Safety hazard 2: inlet temperature

In order to effectively improve the efficiency of the dryer during the drying process of the dryer, the temperature at the inlet end is generally increased. If the temperature is increased, the drying efficiency can be accelerated, and the color of the dried material is blackened, which will affect the drying material. the quality of,

Safety hazard three: drum running speed

In the operation of the dryer, if the speed of the drying material flowing to the outlet direction is reduced by reducing the speed of the drum, the number of dynamic contact between the drying material and the hot air is also reduced. In order to increase the efficiency of the dryer at this time, it is necessary to increase the diameter of the drum and the diameter, which will cause the equipment to occupy an excessively large area and cause heat loss.

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Performance characteristics of gypsum sludge dryer

The gypsum sludge dryer is a low-speed stirring dryer which is equipped with a stirring paddle inside the equipment to make the wet material fully contact with the heat carrier and the hot surface under the agitation of the blade, thereby achieving the purpose of drying. The structure is generally horizontal. , Double or four-axis, special wedge-type stirring heat transfer blades have high heat transfer efficiency and self-cleaning function of heat transfer surface.

Gypsum sludge dryers are divided into hot air and conductive. The hot air type is in contact with the dried material by a heat carrier (such as hot air) and is dried. In the conductive type, the heat carrier is not in direct contact with the material to be dried, but the hot surface is in contact with the material. The advantage of conduction type is that the material is not easily polluted, the displacement is small, the thermal efficiency is high, and the volume is relatively small, which is conducive to saving energy and preventing air pollution.

Performance characteristics of gypsum sludge dryer:

1. The blade dryer system has a low cost: a large heat transfer surface in the effective volume of the unit shortens the processing time and the device size becomes smaller. It greatly reduces the building area and building space.

2. Wide range of processing materials: Different heat media can be used to process both heat sensitive materials and materials requiring high temperature processing. 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.

3. Small environmental pollution: Do not use the carrying air, the dust material is rarely entrained. The solvent evaporation of the material is small and easy to handle. Closed loops can be used for contaminated materials or for conditions requiring recovery of solvents.

4. Low operating costs: the structure. The amount of wear is small and the maintenance cost is low.

5. 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. In the axial interval, the temperature, humidity and mixing gradient of the material are small, thus ensuring Process stability.

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