The high efficiency of drying devices is primarily determined by the generation of impulses by the ceramic itself, which accelerates the slowest stage of drying – the diffusion of water from the deeper layers.
Pulse emitters and IR pulses penetrate deep layers, effectively destroying microorganisms and ensuring sufficient product sterility. Comparative tests were conducted at SPSMI (St. Petersburg) and the Republican Sanitary and Epidemiological Service to evaluate the sterility of products dried using conventional emitters versus those with a ceramic coating that generates IR pulses.
The use of functional ceramics reduced microbial contamination by more than 100,000 times (in fact, complete sterility was observed), whereas conventional heating elements (TENs) achieved only a 5,000-fold reduction.
Pulse emitters and IR pulses penetrate deep layers, effectively destroying microorganisms and ensuring sufficient product sterility. Comparative tests were conducted at SPSMI (St. Petersburg) and the Republican Sanitary and Epidemiological Service to evaluate the sterility of products dried using conventional emitters versus those with a ceramic coating that generates IR pulses.
The use of functional ceramics reduced microbial contamination by more than 100,000 times (in fact, complete sterility was observed), whereas conventional heating elements (TENs) achieved only a 5,000-fold reduction.
Another important parameter is the distribution of power across the shelves in a multi-shelf system. In any case, the best effect is achieved when the power of the lowest group is increased by 15-25%. This applies to large-scale dryers as well.
The reason for this is that the incoming air, which enters from the bottom, is colder than the air in the upper layers.
As the product dries, the amount of water in it decreases, and with constant power, the evaporating moisture may become insufficient to dissipate excess heat. To address this, these dryers include a special mode that allows power to be reduced by half, switching to the so-called "final drying mode."
There is also another, sometimes more advantageous, approach. During drying, products significantly decrease in both mass and volume—for example, onions shrink by a factor of 12, carrots by 8-11 times, and cabbage by up to 40 times. Therefore, after the total mass is reduced by 3-4 times, products from the upper shelves can be transferred to the lower shelves, where the layer thickness will be sufficient to release the necessary amount of moisture for cooling. The freed-up upper shelves can then be reloaded with fresh products.
This method significantly increases the productivity of the drying installation, making it particularly beneficial for larger setups, such as those used by farmers.
One of the main challenges in cabinet drying is the removal of steam generated during water evaporation. If the steam remains trapped in the working chamber, it begins to absorb a significant portion of the energy from the emitters, leading to product overheating. This not only reduces energy efficiency but also severely degrades the quality of the final product, making it dark and unevenly dried.
To address this issue, two steam removal systems have been developed.
Ejector System (Fig. 1): In this case, steam is removed through ejector action. The advantage of this system is that it can be applied to dryers of any size without requiring major structural modifications. Essentially, it creates a pump in the channel between the ejector and the device wall, which efficiently removes moisture released from the products using excess heat. This method eliminates the need for additional energy consumption for forced ventilation of the chamber.
The reason for this is that the incoming air, which enters from the bottom, is colder than the air in the upper layers.
As the product dries, the amount of water in it decreases, and with constant power, the evaporating moisture may become insufficient to dissipate excess heat. To address this, these dryers include a special mode that allows power to be reduced by half, switching to the so-called "final drying mode."
There is also another, sometimes more advantageous, approach. During drying, products significantly decrease in both mass and volume—for example, onions shrink by a factor of 12, carrots by 8-11 times, and cabbage by up to 40 times. Therefore, after the total mass is reduced by 3-4 times, products from the upper shelves can be transferred to the lower shelves, where the layer thickness will be sufficient to release the necessary amount of moisture for cooling. The freed-up upper shelves can then be reloaded with fresh products.
This method significantly increases the productivity of the drying installation, making it particularly beneficial for larger setups, such as those used by farmers.
One of the main challenges in cabinet drying is the removal of steam generated during water evaporation. If the steam remains trapped in the working chamber, it begins to absorb a significant portion of the energy from the emitters, leading to product overheating. This not only reduces energy efficiency but also severely degrades the quality of the final product, making it dark and unevenly dried.
To address this issue, two steam removal systems have been developed.
Ejector System (Fig. 1): In this case, steam is removed through ejector action. The advantage of this system is that it can be applied to dryers of any size without requiring major structural modifications. Essentially, it creates a pump in the channel between the ejector and the device wall, which efficiently removes moisture released from the products using excess heat. This method eliminates the need for additional energy consumption for forced ventilation of the chamber.
Figure 1
The ejector's tilt angle and shape are selected based on the condition that the projection of its lower part should cover the middle of the tray. At the same time, the ejector must not block the radiation path to the product. Only under these conditions is maximum steam removal efficiency ensured.
For multi-level conveyor dryers, the belt speed gradually decreases as the product moves to the lower layers. This leads to the accumulation of thicker product layers, ensuring sufficient moisture release for cooling and enabling the production of high-quality dried products.
It is important to emphasize once again that with the correct design, choice of emitter coating material, and appropriate power, the temperature of the product should be lower than the ambient temperature. Cooling occurs due to intense moisture evaporation.
Of course, air humidity affects the drying speed and product temperature. Our dryers, tested in Malaysia, Singapore, Vietnam, and Thailand—where relative humidity reaches 95-100%—demonstrated excellent results. None of the existing analogs were able to provide proper drying, not to mention their excessive energy consumption and extremely long exposure times.
For multi-level conveyor dryers, the belt speed gradually decreases as the product moves to the lower layers. This leads to the accumulation of thicker product layers, ensuring sufficient moisture release for cooling and enabling the production of high-quality dried products.
It is important to emphasize once again that with the correct design, choice of emitter coating material, and appropriate power, the temperature of the product should be lower than the ambient temperature. Cooling occurs due to intense moisture evaporation.
Of course, air humidity affects the drying speed and product temperature. Our dryers, tested in Malaysia, Singapore, Vietnam, and Thailand—where relative humidity reaches 95-100%—demonstrated excellent results. None of the existing analogs were able to provide proper drying, not to mention their excessive energy consumption and extremely long exposure times.
METHODOLOGY FOR CALCULATING EMITTERS FOR DRYING CABINETS
A system has been developed that enables efficient drying with the highest product quality and high sterility while minimizing energy and time consumption.
Based on this system, numerous drying installations have been created for various fields.
Based on this system, numerous drying installations have been created for various fields.
CONVEYOR DRYING OF PASTA PRODUCTS
The production of pasta consists of many operations. The main and most important operation is the drying of pasta products. Different types of pasta are dried at different temperatures, which affects the drying time.
Tubular and long pasta products are dried at low temperatures (30-40°C) for 20-36 hours, sometimes even longer. If the temperature is increased to 50-55°C, the drying time is reduced to 12-14 hours. This is known as the normal drying mode.
Short-cut pasta is dried at 50-55°C for 4-8 hours, excluding the stabilization time, which takes at least another 3-4 hours.
In high-temperature drying modes (70-85°C), long pasta products are dried for about 10 hours, while short-cut pasta takes about 3-6 hours.
Ultra-high-temperature drying is carried out at 100-130°C. Long pasta is dried for 4-6 hours, while short-cut pasta takes between 1 hour 20 minutes and 2 hours 40 minutes.
These process parameters correspond to reducing the product's initial moisture content from 30% to 12.5%. Drying is carried out in various types of dryers, including non-calorific, conveyor, and chamber dryers.
With conventional drying methods, excessively fast drying can cause cracking, leading to increased breakage and crumbs. On the other hand, slow drying (especially with additional humidification of the chambers) can promote the growth of harmful microflora in pasta, such as acid-forming bacteria (which increase the acidity of the product), molds, and Bact. Levans, which cause pasta swelling and spoilage.
The most important challenges in pasta production are:
Tubular and long pasta products are dried at low temperatures (30-40°C) for 20-36 hours, sometimes even longer. If the temperature is increased to 50-55°C, the drying time is reduced to 12-14 hours. This is known as the normal drying mode.
Short-cut pasta is dried at 50-55°C for 4-8 hours, excluding the stabilization time, which takes at least another 3-4 hours.
In high-temperature drying modes (70-85°C), long pasta products are dried for about 10 hours, while short-cut pasta takes about 3-6 hours.
Ultra-high-temperature drying is carried out at 100-130°C. Long pasta is dried for 4-6 hours, while short-cut pasta takes between 1 hour 20 minutes and 2 hours 40 minutes.
These process parameters correspond to reducing the product's initial moisture content from 30% to 12.5%. Drying is carried out in various types of dryers, including non-calorific, conveyor, and chamber dryers.
With conventional drying methods, excessively fast drying can cause cracking, leading to increased breakage and crumbs. On the other hand, slow drying (especially with additional humidification of the chambers) can promote the growth of harmful microflora in pasta, such as acid-forming bacteria (which increase the acidity of the product), molds, and Bact. Levans, which cause pasta swelling and spoilage.
The most important challenges in pasta production are:
- increasing productivity while reducing energy consumption,
- improving the consumer qualities of the final product (appearance, cooking properties), and most importantly, enhancing its nutritional value.
As it turned out, all of this can be achieved by incorporating specially selected functional-purpose pulsed ceramics into the drying process, which is applied to the infrared (IR) emitting elements.
Using such elements, an experimental conveyor for drying pasta products was designed, calculated, and manufactured. It was tested at the pasta production facility of the company "Tsesna-Tau," which kindly provided us with the opportunity to test the method and device (Almaty, Kazakhstan).
Initial design specifications:
Using such elements, an experimental conveyor for drying pasta products was designed, calculated, and manufactured. It was tested at the pasta production facility of the company "Tsesna-Tau," which kindly provided us with the opportunity to test the method and device (Almaty, Kazakhstan).
Initial design specifications:
- a conveyor-type dryer with a mesh belt 600 mm wide.
- working zone length – 3550 mm.
- working length of the elements – 620 mm. The elements are positioned perpendicular to the belt movement, above the product and below the mesh.
- The base of the elements is a quartz tube with a diameter of 12 mm.
- Total quantity – 64 emitters.
- Total rated power – 9400 W.
The emitting elements had different electrical parameters depending on their location within the working zone of the line. The working zone was divided into three sections with varying ceramic radiation activity. At the beginning of the line, a high-intensity radiant energy flow was generated, rapidly bringing the product's temperature to the required drying regime. The product then entered the main intensive drying zone. Finally, in the third deep-drying zone, with a reduced sublimation rate, the product’s moisture content was lowered to the minimum possible level given the line's speed and limited length.
The primary purpose of the experimental conveyor was initially to demonstrate the feasibility of using specialized functional ceramics in the pasta drying process.
A comparison was made with the Italian equipment used in the facility. The technological process design for pasta production was carried out by Z.D.J. Engineering Limited, with Dr. Milan Žeželj as the project designer.
The best traditional drying process is presented in Table 1.
The drying was performed in a cabinet-type dryer (with a capacity equivalent to the experimental conveyor), with a power rating of 31,000 W.
Data on our experimental drying:
The primary purpose of the experimental conveyor was initially to demonstrate the feasibility of using specialized functional ceramics in the pasta drying process.
A comparison was made with the Italian equipment used in the facility. The technological process design for pasta production was carried out by Z.D.J. Engineering Limited, with Dr. Milan Žeželj as the project designer.
The best traditional drying process is presented in Table 1.
The drying was performed in a cabinet-type dryer (with a capacity equivalent to the experimental conveyor), with a power rating of 31,000 W.
Data on our experimental drying:
- Flour (semolina) from soft wheat according to GOST 20394-87.
- Initial dough moisture – 30% (dough without egg additives or enrichments).
- Product residence time in the conveyor working zone – 7 minutes 30 seconds.
- Pasta shape – noodles (a sheet 15-17 mm wide with wavy edges and a length of 20-30 mm) and elbow macaroni (outer diameter about 5 mm, wall thickness 1.5 mm, length 20-30 mm). The dimensions are given for dried products.
The trial run on the experimental conveyor showed that after drying, the products were firm and elastic, with a glassy fracture and a uniform structure throughout their depth.
Table 1. Convection Drying in a Cabinet-Type Dryer
Determining the drying dynamics involved measuring the weight of control samples. Three samples of 1000 ± 2 g were prepared for this purpose. The conveyor belt was fully loaded along its entire length.
The control zones were positioned within the product flow. After a single pass of the product through the active zone in 7 minutes 30 seconds, the following results were obtained:
The control zones were positioned within the product flow. After a single pass of the product through the active zone in 7 minutes 30 seconds, the following results were obtained:
Table 2. Results (by weight) of Control Drying
On average, the residual weight after the pass was 880.76 g, which corresponds to 20% residual moisture with an initial dough moisture of 30%.
From the drying dynamics graphs in Figure 4, it is evident that compared to control drying on standard convection-type equipment (with the same capacity), where similar results were achieved in 60 minutes, IR drying with functional ceramics was 8 times faster.
Per unit of product, the experimental conveyor consumed 26 times less energy compared to the traditional method.
Per unit of product, the experimental conveyor consumed 26 times less energy compared to the traditional method.
Table 3. Economic Indicators of the Drying Process Using the Experimental Conveyor
The pre-dried products were placed on trays and left in the open air for further drying and stabilization. In terms of appearance, the finished products were indistinguishable from similar products obtained through the traditional drying method described in Table 3.
The cooking results are summarized in Table 4.
The cooking results are summarized in Table 4.
Table 4. Consumer and Quality Properties of Dried Pasta Products
The result. When comparing item 1 and item 3 (even with the cooking time increased from 12 minutes to 16 minutes), it is clearly evident that the product did not overcook or stick together.
From the given graph characterizing classical drying processes in an enclosed space, it is evident that the use of forced ventilation can yield better results in terms of drying dynamics.
Based on the experimental work conducted on conveyor drying of pasta products using spectrum converters, the following conclusions were drawn:
The double pass under the active zone of the control batch of the product with intermediate cooling led to some deterioration in consumer properties compared to a single pass. This is due to the fact that the drying process using functional ceramics should not be interrupted by removing the product from the active radiation zone, as this disrupts the drying dynamics and causes irreversible changes in the product, which worsens its consumer properties.
The drying processes for pasta using pulse IR converters significantly differ from the conventional ones. During drying, it is necessary to ensure continuous removal of the steam emitted by the product through blown air. Since the steam emitted by the product hinders the passage of rays deep into the structure and mass of the product itself, the energy of the rays will start being absorbed by the steam. It overheats, leading to secondary heating of the product and disruption of the drying process dynamics. Drying can slow down significantly, leading to spoilage of the product itself (the product starts to 'cook' in the steam). Quality indicators will begin to approach those of products dried by traditional methods. The use of closed chambers with additional humidification is not acceptable.
It should be noted that the above data were obtained without the use of flow exhaust ventilation, in conditions of high humidity in the workshop.
From the given graph characterizing classical drying processes in an enclosed space, it is evident that the use of forced ventilation can yield better results in terms of drying dynamics.
Based on the experimental work conducted on conveyor drying of pasta products using spectrum converters, the following conclusions were drawn:
To calculate a highly economical and optimal design for the conveyor using functional ceramics, the following principles should be considered:
- Expected performance of the complex;
- Width of the applied conveyor belt;
- The weight of the product loading per unit area (at various drying stages), which, in turn, depends on the geometric shape of the items;
- Local installation conditions of the equipment, which significantly affect the gas dynamics of the complex;
- Optimal distribution of emitters and their power within the device, depending on the current stage of the drying process, as well as many other related specific factors affecting the drying processes, which, however, can be taken into account.
It is also possible to significantly improve and optimize the drying dynamics by incorporating emitters with various types of functional ceramics into the conveyor design.
Some types of ceramics have better parameters at the initial drying stage, while others are more effective in the middle of the process. Additionally, there are ceramic emitters that ensure more economical and higher-quality final drying of the product.
By considering all the above-mentioned factors and their influence on the drying process during the design phase, it is possible to achieve significantly better economic and quality characteristics compared to those obtained in the tested experimental conveyor.
The main advantages of drying conveyors for pasta production using special functional ceramics are:
Some types of ceramics have better parameters at the initial drying stage, while others are more effective in the middle of the process. Additionally, there are ceramic emitters that ensure more economical and higher-quality final drying of the product.
By considering all the above-mentioned factors and their influence on the drying process during the design phase, it is possible to achieve significantly better economic and quality characteristics compared to those obtained in the tested experimental conveyor.
The main advantages of drying conveyors for pasta production using special functional ceramics are:
- High economic efficiency;
- Improved consumer properties of the final product (boilability, stickiness, etc.);
- Significantly longer shelf life due to the sterilizing effect of the ceramics;
- High quality and nutritional value of the product, as nearly all active and natural flavor components introduced during dough mixing are preserved;
- Possibility of fully automating the entire production process—from dough mixing to packaging the finished product—within a single integrated system.
Using pasta as an example, we have seen that the application of pulses not only provided a significant economic effect, reduced labor intensity, and shortened drying time but also drastically improved product quality—something that would surely delight the hearts of Italians and pasta lovers everywhere!
CONVEYOR DRYING OF MATERIALS
A prototype of a universal drying module has been developed for drying bulk materials, allowing the drying process to be carried out in high-risk production environments. The conveyor module is equipped with dust protection, is electrically safe, explosion-proof, and can operate in open spaces and under shelters. The module is installed above the conveyor belt, with no limitations on the number of modules that can be installed. The main parameters of the module are as follows:
- Dimensions: 480 × 600 × 180 mm
- Maximum power: 600 Watts (adjustable from 50 to 600 Watts with remote control capability)
- Conveyor belt width: 400 mm (adaptable to other belt sizes with corresponding adjustments in overall power)
- Length of the active irradiation zone: 500 mm
In collaboration with LLC "Infra-Polymer" and PO "Uzbekrezinotekhnika," tests were conducted on a conveyor composed of 10 identical modules, with an active working zone of 5 meters.
Figure 6 illustrates the drying dynamics of chalk at various initial moisture levels. The conveyor was designed for drying bulk ingredients used in the production of rubber-technical products, including chalk, kaolin, carbon black, zinc white, sulfur, rosin, thiuram, microcalcite, and similar materials. However, it can also be utilized in other industries requiring the drying of such materials.
As a result of the test drying cycles, compared to standard equipment of a similar class, the performance of infrared drying with spectrum converters was found to be three times higher, while energy consumption was three times lower. The total energy savings amounted to a ninefold reduction.
As previously noted, modular blocks and conveyors of the required length assembled from them can be successfully applied in various industries and raw material processing fields.
For instance, conveyor drying transporters can be effectively used in grain storage facilities and the milling industry. In these cases, the sterilizing properties of functional drying ceramics are especially important. Products dried using this method have an extended shelf life without altering their quality characteristics.
Figure 6 illustrates the drying dynamics of chalk at various initial moisture levels. The conveyor was designed for drying bulk ingredients used in the production of rubber-technical products, including chalk, kaolin, carbon black, zinc white, sulfur, rosin, thiuram, microcalcite, and similar materials. However, it can also be utilized in other industries requiring the drying of such materials.
As a result of the test drying cycles, compared to standard equipment of a similar class, the performance of infrared drying with spectrum converters was found to be three times higher, while energy consumption was three times lower. The total energy savings amounted to a ninefold reduction.
As previously noted, modular blocks and conveyors of the required length assembled from them can be successfully applied in various industries and raw material processing fields.
For instance, conveyor drying transporters can be effectively used in grain storage facilities and the milling industry. In these cases, the sterilizing properties of functional drying ceramics are especially important. Products dried using this method have an extended shelf life without altering their quality characteristics.
CONVEYOR DRYING OF RICE AND DRYING OF FRUITS AND VEGETABLES UNDER HIGH HUMIDITY AND TEMPERATURE CONDITIONS
The task of processing and preserving the harvested rice crop is not only faced by Southeast Asian countries. This issue also exists in Europe and the United States. It can be said that about one-third of the harvested crop is lost due to the imperfections in processing and storage methods, the most important of which are drying and preliminary sterilization of the grain. The effectiveness of traditional drying methods is very low, especially in conditions of high atmospheric humidity. Together with the Post-Harvest Technology Institute (Vietnam, one of the major rice producers and consumers), research was conducted on the effectiveness of drying using functional pulse ceramics.
Based on the serial dryer "VOSTOK," our development, equipped with elements covered with functional ceramics, control drying of products was performed. The results were compared with a high-performance serial infrared ray dryer (without ceramics) made in China. The quality of the drying results on the "VOSTOK" dryer was better, even when using serial-type ceramic emitters without optimization for the grain. Based on the data obtained, an analysis of the test drying results was carried out. In the local tropical climate conditions of the dryer installation's operation, the type of ceramics was selected, and the emitter power was adjusted. Since water vapor intensely absorbs infrared radiation, increasing its concentration in the air leads to a significant reduction in the "signal" of the pulse emitted by the emitters. Therefore, it is necessary to increase the proportion of pulses produced by the ceramics. In our case, this can be easily achieved by increasing the concentration of pulse ceramics in the "diluent," that is, in the mullite.
The test of the upgraded serial device "Vostok" and a series of new control tests showed that drying time decreased by 1.6 to 3.5 times compared to the previous values (obtained on the serial "VOSTOK" device), while the quality was higher. We call it "Vostok – InfraR".
All the comparative data provided below were supplied by the Post-Harvest Technology Institute. These data were obtained under tropical climate conditions with high humidity, under the most unfavorable conditions for drying grains, fruits, and vegetables. As mentioned earlier, the comparison was made with the serial drying device from China, as the closest prototype.
Based on the serial dryer "VOSTOK," our development, equipped with elements covered with functional ceramics, control drying of products was performed. The results were compared with a high-performance serial infrared ray dryer (without ceramics) made in China. The quality of the drying results on the "VOSTOK" dryer was better, even when using serial-type ceramic emitters without optimization for the grain. Based on the data obtained, an analysis of the test drying results was carried out. In the local tropical climate conditions of the dryer installation's operation, the type of ceramics was selected, and the emitter power was adjusted. Since water vapor intensely absorbs infrared radiation, increasing its concentration in the air leads to a significant reduction in the "signal" of the pulse emitted by the emitters. Therefore, it is necessary to increase the proportion of pulses produced by the ceramics. In our case, this can be easily achieved by increasing the concentration of pulse ceramics in the "diluent," that is, in the mullite.
The test of the upgraded serial device "Vostok" and a series of new control tests showed that drying time decreased by 1.6 to 3.5 times compared to the previous values (obtained on the serial "VOSTOK" device), while the quality was higher. We call it "Vostok – InfraR".
All the comparative data provided below were supplied by the Post-Harvest Technology Institute. These data were obtained under tropical climate conditions with high humidity, under the most unfavorable conditions for drying grains, fruits, and vegetables. As mentioned earlier, the comparison was made with the serial drying device from China, as the closest prototype.
It is known that the higher the level of cracking, the greater the amount of rice that is scratched and husked, and consequently, its quality and consumer properties decrease. Therefore, the main requirements in the rice drying process are economy and drying speed, with minimal grain cracking. The drying industry must ensure the lowest level of losses.
The level of cracking in the grain was determined at the Post-Harvest Technology Institute using a well-known method. 100 paddy grains were placed on a silvered glass under a fluorescent lamp, and the level of cracking (percentage ratio) was determined.
By studying the comparative drying data, the obtained drying dynamics for rice, corn, and barley, the influence of the drying grain's density on the necessary infrared radiation power, as well as the effect of drying temperature (at different external air temperatures) on the cracking of the grain, a multi-tiered conveyor of the bulk type was designed.
The conveyor is a cabinet-type structure, sized 2880 mm x 900 mm x 2800 mm.
Seven rows of conveyor grids, each 600 mm wide, are installed offset so that the product, during drying, is transferred from the upper rows to the lower rows moving in the opposite direction. The emitters are installed along the direction of the conveyor grid's movement. The distance between the elements, the distance from the grid to the elements, and the power of the emitters were chosen to ensure a uniform flow of radiant energy, penetrating a specific thickness of the rice layer being dried.
The total length of the active zone is 14 meters. The rate of moisture evaporation from the product, under normal atmospheric pressure, is limited by the structure of the product itself (its density). Increasing the active zone length in a single design turned out to be impractical. Increasing the length of the active zone would result in an increase in conveyor speed. This would require a significant increase in the power supply to the infrared flow and in the power of the drives, as the weight load on the conveyor belt would increase. The designed conveyor is intended to operate in close proximity to processing and storage areas, where, as a rule, the load on the electrical network is limited by the power of small substations.
Given the tasks set, consumers concluded that the productivity, dimensions, and power load characteristics are optimal for this design. Further, structural modifications can be made based on specific tasks.
The results of control drying of products showed that only by testing dryer prototypes in real operational conditions can the quality and performance characteristics of the drying complexes be achieved, as their operation involves many interrelated factors. In all cases, adapting devices to specific climatic conditions and technical norms significantly improves the drying process (for example, remember the choice of ceramics for high humidity conditions) compared to serial equipment used for wide applications. This has been confirmed, as mentioned earlier, by reports from the Post-Harvest Technology Institute of Vietnam, which stated that after correcting the dryer and ceramics, the drying speed increased 1.6 to 3.5 times for each product (under different external conditions) with better quality of the final product.
The level of cracking in the grain was determined at the Post-Harvest Technology Institute using a well-known method. 100 paddy grains were placed on a silvered glass under a fluorescent lamp, and the level of cracking (percentage ratio) was determined.
By studying the comparative drying data, the obtained drying dynamics for rice, corn, and barley, the influence of the drying grain's density on the necessary infrared radiation power, as well as the effect of drying temperature (at different external air temperatures) on the cracking of the grain, a multi-tiered conveyor of the bulk type was designed.
The conveyor is a cabinet-type structure, sized 2880 mm x 900 mm x 2800 mm.
Seven rows of conveyor grids, each 600 mm wide, are installed offset so that the product, during drying, is transferred from the upper rows to the lower rows moving in the opposite direction. The emitters are installed along the direction of the conveyor grid's movement. The distance between the elements, the distance from the grid to the elements, and the power of the emitters were chosen to ensure a uniform flow of radiant energy, penetrating a specific thickness of the rice layer being dried.
The total length of the active zone is 14 meters. The rate of moisture evaporation from the product, under normal atmospheric pressure, is limited by the structure of the product itself (its density). Increasing the active zone length in a single design turned out to be impractical. Increasing the length of the active zone would result in an increase in conveyor speed. This would require a significant increase in the power supply to the infrared flow and in the power of the drives, as the weight load on the conveyor belt would increase. The designed conveyor is intended to operate in close proximity to processing and storage areas, where, as a rule, the load on the electrical network is limited by the power of small substations.
Given the tasks set, consumers concluded that the productivity, dimensions, and power load characteristics are optimal for this design. Further, structural modifications can be made based on specific tasks.
The results of control drying of products showed that only by testing dryer prototypes in real operational conditions can the quality and performance characteristics of the drying complexes be achieved, as their operation involves many interrelated factors. In all cases, adapting devices to specific climatic conditions and technical norms significantly improves the drying process (for example, remember the choice of ceramics for high humidity conditions) compared to serial equipment used for wide applications. This has been confirmed, as mentioned earlier, by reports from the Post-Harvest Technology Institute of Vietnam, which stated that after correcting the dryer and ceramics, the drying speed increased 1.6 to 3.5 times for each product (under different external conditions) with better quality of the final product.
- It was necessary to increase the power of the lower group of emitters by 15-20% while maintaining the total power.
- It was necessary to increase the content of "pulse" ceramics in the coating composition from 0.5% to 1%.
Thus, in areas with high humidity, products can be dried at almost the same speed and efficiency as in areas with normal relative air humidity, by selecting the appropriate ceramics and redistributing the power in the drying equipment.
BOX DRYING OF INDUSTRIAL MATERIALS AND PRODUCTS
The use of functional ceramics in drying processes has significantly improved the quality indicators when drying industrial materials.
A large number of test measurements on the drying dynamics of various technical materials were carried out at InfraRot Anlagen GmbH (Germany).
A large number of test measurements on the drying dynamics of various technical materials were carried out at InfraRot Anlagen GmbH (Germany).
- Drying of ceramic blanks for industrial catalysts;
- Drying and fixation of casting molds;
- Drying of wood and wood chips;
- Drying of porcelain, etc.
DRYING OF INDUSTRIAL CATALYSTS
At the request of SIEMENS regarding the possibility of using infrared (IR) drying for special blanks for industrial catalysts, comparative control drying tests were conducted. The blanks contain, in addition to titanium, tungsten, and vanadium oxides, special organic binder compositions. Therefore, the temperature of the blank during drying is limited and should not exceed 60 degrees Celsius. The company currently dries these blanks (using traditional technologies) over a period of 10 days (240 hours) or more. During the initial control tests on the "VOSTOK" unit, this time was reduced to just 12 hours. Quality checks on the drying process and the preservation of the structure of organic compounds by SIEMENS yielded positive results. Work was carried out to select optimal operating modes and ceramics for the drying of catalysts.
For further testing, a special drying cabinet "MONSUN" was manufactured. The cabinet allows for the drying of up to 75 large catalysts with dimensions of 600x70x70 mm.
The dimensions of the working area of the cabinet (640 mm x 1000 mm x 1750 mm) are divided into five shelves. The rated power of the cabinet is 8040 watts.
Drying control samples of catalysts in this cabinet showed the following results regarding the dynamics of the process. The initial moisture content of the catalyst is 27%. The final moisture content is around 3%. The temperature of the samples is 50-55 degrees Celsius.
Compared to the standard drying methods used by SIEMENS, the drying time is reduced from 240 hours to 3 hours. The drying time is reduced by 80 times!
The energy consumption per catalyst is 321.6 watts over 3 hours of cabinet operation. It takes 0.1 kW/h of electricity per catalyst per hour, making the drying process economically affordable.
For further testing, a special drying cabinet "MONSUN" was manufactured. The cabinet allows for the drying of up to 75 large catalysts with dimensions of 600x70x70 mm.
The dimensions of the working area of the cabinet (640 mm x 1000 mm x 1750 mm) are divided into five shelves. The rated power of the cabinet is 8040 watts.
Drying control samples of catalysts in this cabinet showed the following results regarding the dynamics of the process. The initial moisture content of the catalyst is 27%. The final moisture content is around 3%. The temperature of the samples is 50-55 degrees Celsius.
Compared to the standard drying methods used by SIEMENS, the drying time is reduced from 240 hours to 3 hours. The drying time is reduced by 80 times!
The energy consumption per catalyst is 321.6 watts over 3 hours of cabinet operation. It takes 0.1 kW/h of electricity per catalyst per hour, making the drying process economically affordable.
WOOD DRYING
In the same "MONSUN" cabinet, control drying of wood was carried out. The room temperature was 27 degrees Celsius, and the drying was done without ventilation. The humidity in the room before starting the drying process was 60%, and the humidity in the room at the end of the process was 80%. The drying process took 3 hours and 30 minutes, with the active working time of the cabinet being 2 hours.
Wood drying (SPRUCE) was done with an initial moisture content of 20% and ventilation set to 25 cubic meters per hour. The beam dimensions were 30 mm x 100 mm x 900 mm. The drying process was conducted with intermittent energy supply (IR) at elevated temperatures, with 10 minutes of active mode followed by 20 minutes of passive mode, and so on.
Additionally, wood chips were dried in the "MONSUN" cabinet. The initial moisture content of the chips was 20%, and the final moisture content was 2-3%. The drying time was less than 30 minutes.
Wood drying (SPRUCE) was done with an initial moisture content of 20% and ventilation set to 25 cubic meters per hour. The beam dimensions were 30 mm x 100 mm x 900 mm. The drying process was conducted with intermittent energy supply (IR) at elevated temperatures, with 10 minutes of active mode followed by 20 minutes of passive mode, and so on.
Additionally, wood chips were dried in the "MONSUN" cabinet. The initial moisture content of the chips was 20%, and the final moisture content was 2-3%. The drying time was less than 30 minutes.
WOOD FLOORING DRYING
While conventional dryers cause wood to crack during the drying process, ours, on the contrary, "heals" such cracks. We obtain dried parquet blanks that are irregularly shaped. Then, using a special mold, the desired geometric configuration is pressed. The design can first be drawn on a computer and then broken down into standard, diverse elements. Molds are created specifically for pressing these elements.
The process is very easy, as the cuts are made transversely.
The following photographs show blanks made from various wood species and a small fragment assembled after further processing.
This parquet is glued to the base with woodworking glue, such as PVA, and then sanded and covered with parquet varnish. Notably, any natural wood pattern can be chosen, allowing for the creation of different compositions.
One "Uzbekistan" unit, occupying 0.7 square meters of space, can dry 30-40 square meters of such parquet per day.
The process is very easy, as the cuts are made transversely.
The following photographs show blanks made from various wood species and a small fragment assembled after further processing.
This parquet is glued to the base with woodworking glue, such as PVA, and then sanded and covered with parquet varnish. Notably, any natural wood pattern can be chosen, allowing for the creation of different compositions.
One "Uzbekistan" unit, occupying 0.7 square meters of space, can dry 30-40 square meters of such parquet per day.
DRYUNG OF FRUIT PASTES, SPECIALTY PRODUCTS, AND ANIMAL FEED
In the universal "MONSUN" drying cabinet, in collaboration with InfraRot and LIHOTZKY companies, work was carried out to dry fruit pastes. Chips made from dried fruit paste are a completely new product, and therefore, there is no "standard" technology for their production.
All attempts by LIHOTZKY to dry fruit paste using other methods, such as in conventional dryers, ovens, or microwave ovens, did not yield positive results. The fruit paste itself, due to its high sugar content, is highly sensitive to overheating during drying. Overheating or burning of the product imparts a burnt sugar taste to the products due to the combustion of fruit sugars, leading to the loss of extractive aromatic compounds, which results in the loss of the specific taste characteristic of each product. Conventional low-temperature drying does not allow fruit paste to be dried to a level of minimal moisture, where the crispy properties characteristic of chips are achieved.
Positive results were only obtained on our drying installation, equipped with radiating elements covered with special functional ceramics.
For the trials, date paste with a moisture content of 17-18% and glucose content of around 35% was used. To achieve the specific "quality" properties inherent in this product, the residual moisture of the date paste should not exceed 3%. Below, in Table 17, an example of drying in the "MONSUN" cabinet is shown. The drying time for control samples of fruit paste ranged from 7 to 12 minutes (depending on the drying cabinet load and the product).
Since chips made from fruit pastes are a completely new product, which can only be obtained in dryers equipped with special functional ceramics, as mentioned earlier, we cannot provide comparative results.
All attempts by LIHOTZKY to dry fruit paste using other methods, such as in conventional dryers, ovens, or microwave ovens, did not yield positive results. The fruit paste itself, due to its high sugar content, is highly sensitive to overheating during drying. Overheating or burning of the product imparts a burnt sugar taste to the products due to the combustion of fruit sugars, leading to the loss of extractive aromatic compounds, which results in the loss of the specific taste characteristic of each product. Conventional low-temperature drying does not allow fruit paste to be dried to a level of minimal moisture, where the crispy properties characteristic of chips are achieved.
Positive results were only obtained on our drying installation, equipped with radiating elements covered with special functional ceramics.
For the trials, date paste with a moisture content of 17-18% and glucose content of around 35% was used. To achieve the specific "quality" properties inherent in this product, the residual moisture of the date paste should not exceed 3%. Below, in Table 17, an example of drying in the "MONSUN" cabinet is shown. The drying time for control samples of fruit paste ranged from 7 to 12 minutes (depending on the drying cabinet load and the product).
Since chips made from fruit pastes are a completely new product, which can only be obtained in dryers equipped with special functional ceramics, as mentioned earlier, we cannot provide comparative results.
DRYING OF METHIONINE, HERBS, ANIMAL FEED, AND OTHER BIOOBJECTS
The DEGUSSA Group is involved in the production of specialty products, such as methionine. This amino acid cannot be dried using conventional methods, as it undergoes destruction during the process. The drying method using special functional ceramics turned out to be the only acceptable technology for drying this material. Drying to a specific residual moisture content, depending on the applied power, takes between 10 and 25 minutes.
Preliminary research work has also been carried out in preparation for the industrial application of the drying method using IR ceramic converters in the following areas:
Preliminary research work has also been carried out in preparation for the industrial application of the drying method using IR ceramic converters in the following areas:
- Drying of herbs and plant-based feeds for use in livestock and poultry farming, as well as drying of dog food. The dried feeds obtained have a high content of vitamins and essential nutrients, which characterize the quality of the products.
- Drying of packaging material made from biological raw materials (biological packaging material).
- Drying of rusks (the rusks become especially delicate and crumbly).
- Drying of malt (brewing).
- Drying of soups and various dishes, including pilaf, to create food in the form of instant concentrates, while preserving all the taste and quality characteristics of the finished product.
Physico-chemical studies of the quality of finished products and calculations of the loss of essential nutrients during IR drying with the use of ceramic converters in the spectrum indicate that only this drying method ensures the highest preservation of proteins, lipids, biologically active and extractive substances, as well as vitamins. The absence of microbial contamination in the products indicates their good sanitary and bacteriological condition, which positively impacts their shelf life. None of the semi-finished products studied showed the presence of conditionally pathogenic or pathogenic bacteria, and the finished products had a low coliform count.
The organoleptic evaluation of the quality of the product after drying was conducted on a product that is difficult to dry and almost completely loses its taste qualities—Uzbek pilaf. The quality assessment was based on the experimental determination of the sensory sensitivity of the tasters. The results show that indicators such as taste, aroma, juiciness, and consistency in the rehydrated product are the same as in freshly prepared pilaf.
By using dryers equipped with radiating elements covered with functional ceramics, it becomes possible to prepare dishes and products for relatively long storage, which have undergone full cooking stages and retain high nutritional and quality properties. All control and comparative drying of various products and industrial materials demonstrated that by using special functional pulse ceramics, high economic and quality indicators can be achieved in the drying process of various products and industrial technical materials.
The organoleptic evaluation of the quality of the product after drying was conducted on a product that is difficult to dry and almost completely loses its taste qualities—Uzbek pilaf. The quality assessment was based on the experimental determination of the sensory sensitivity of the tasters. The results show that indicators such as taste, aroma, juiciness, and consistency in the rehydrated product are the same as in freshly prepared pilaf.
By using dryers equipped with radiating elements covered with functional ceramics, it becomes possible to prepare dishes and products for relatively long storage, which have undergone full cooking stages and retain high nutritional and quality properties. All control and comparative drying of various products and industrial materials demonstrated that by using special functional pulse ceramics, high economic and quality indicators can be achieved in the drying process of various products and industrial technical materials.
FIXATION AND HEAT TREATMENT OF CASTING MOLDS
Based on InfraRot Anlagen GmbH (Germany) in collaboration with the AST Group, which specializes in the development and manufacture of complexly shaped casting molds, a special device was developed for stabilizing and fixing casting molds.
Typically, a disposable mold is formed layer by layer with a laser in a special device using a thermally fixable powder. The laser-formed mold is placed into a large metal thick-walled box, carefully filling the free space layer by layer with small quartz spheres. This is necessary to prevent the mold from warping during the baking process, as the mold-forming composition initially has high plasticity during heat treatment. This box is placed into a large electric furnace with a capacity of over 50 kW, the temperature is raised to 350°C, and it is held at this temperature for 12-14 hours. For the fixing composition, it is preferable to set the furnace temperature at 600-650°C for complete and high-quality fixation of the composition. However, due to the long time required to equalize the temperature gradient within the box, the outer layers carbonize, while the inner and central layers remain raw, as the thermal conductivity of the mold-forming material is very low. In practice, to prevent material destruction, the holding time in the furnace and the temperature are reduced. Costs increase, and the product becomes very expensive. Additionally, there is no guarantee that the use of quartz spheres will not cause geometric distortion of the complex casting mold.
We designed, manufactured, and tested a special working chamber in which the entire process of fixing the mold and its final adjustment to the finished state takes from 5 to 12 minutes, depending on the size and weight of the casting mold. A manual device was also developed for the quick fixation (stabilization) of raw casting molds with complex configurations, which are difficult to move to the furnace due to the increased brittleness of the raw, unbaked material. At the final stage of heat treatment, the temperature of the sample reached the recommended 650°C. The power rating of the system was 3 kW.
As a result, the heat treatment time was reduced by 60 times. Compared to conventional furnaces, the energy consumption for the entire heat treatment process was reduced from 300-600 kW/h (depending on the load) to 0.6 kW/h. The total energy consumption decreased by 500-1000 times!
As you can see, the fixation and heat treatment process is based on the fact that functional ceramics transform the energy beam emitted by the heating element. By applying various ceramic coatings (changing the pulse component), we achieve a working energy beam that penetrates deeper into the material, where it is uniformly absorbed by the material forming the casting mold. With this type of energy beam exposure and subsequent heat treatment, the mold is quickly fixed. The temperature range at which the material has increased plasticity is effectively eliminated, and there is no need to use quartz spheres to fill the molds, nor is there a need for special metal boxes.
As a result of the work carried out, the entire process of fixing and heat treating special casting molds has been significantly simplified.
Typically, a disposable mold is formed layer by layer with a laser in a special device using a thermally fixable powder. The laser-formed mold is placed into a large metal thick-walled box, carefully filling the free space layer by layer with small quartz spheres. This is necessary to prevent the mold from warping during the baking process, as the mold-forming composition initially has high plasticity during heat treatment. This box is placed into a large electric furnace with a capacity of over 50 kW, the temperature is raised to 350°C, and it is held at this temperature for 12-14 hours. For the fixing composition, it is preferable to set the furnace temperature at 600-650°C for complete and high-quality fixation of the composition. However, due to the long time required to equalize the temperature gradient within the box, the outer layers carbonize, while the inner and central layers remain raw, as the thermal conductivity of the mold-forming material is very low. In practice, to prevent material destruction, the holding time in the furnace and the temperature are reduced. Costs increase, and the product becomes very expensive. Additionally, there is no guarantee that the use of quartz spheres will not cause geometric distortion of the complex casting mold.
We designed, manufactured, and tested a special working chamber in which the entire process of fixing the mold and its final adjustment to the finished state takes from 5 to 12 minutes, depending on the size and weight of the casting mold. A manual device was also developed for the quick fixation (stabilization) of raw casting molds with complex configurations, which are difficult to move to the furnace due to the increased brittleness of the raw, unbaked material. At the final stage of heat treatment, the temperature of the sample reached the recommended 650°C. The power rating of the system was 3 kW.
As a result, the heat treatment time was reduced by 60 times. Compared to conventional furnaces, the energy consumption for the entire heat treatment process was reduced from 300-600 kW/h (depending on the load) to 0.6 kW/h. The total energy consumption decreased by 500-1000 times!
As you can see, the fixation and heat treatment process is based on the fact that functional ceramics transform the energy beam emitted by the heating element. By applying various ceramic coatings (changing the pulse component), we achieve a working energy beam that penetrates deeper into the material, where it is uniformly absorbed by the material forming the casting mold. With this type of energy beam exposure and subsequent heat treatment, the mold is quickly fixed. The temperature range at which the material has increased plasticity is effectively eliminated, and there is no need to use quartz spheres to fill the molds, nor is there a need for special metal boxes.
As a result of the work carried out, the entire process of fixing and heat treating special casting molds has been significantly simplified.