Drying seeds. Features of drying sunflower seeds in mine grain dryers How to dry a seed in a vacuum chamber
Dried seeds are not only tasty, but also a very healthy snack. Pumpkin, sunflower, and sesame seeds are rich in vitamins, macro- and microelements that have a beneficial effect on human health. True, only if they are properly prepared.
Sunflower
Unpeeled raw sunflower seeds can be bought in a store or collected yourself (if this grows on your country plot or friends’ dacha beautiful plant). First of all, the seeds need to be washed well. To do this, place them in a colander or large sieve and sort them under running water, getting rid of debris and dust. Then shake the seeds thoroughly and place them in a thin layer on a napkin or piece of cloth. Leave them in direct sunlight (outside, balcony or windowsill) for about 4 hours until completely dry. Stir the seeds periodically to ensure even drying.
If you don't want to wait several hours, take advantage of the options household appliances. The seeds can be dried in the oven or microwave oven. In the first case, place the sunflower seeds on a baking sheet in one layer and place them in an oven preheated to +180 °C for 20 minutes. Another option is to place the seeds on a flat plate in the microwave on high for 20-25 minutes. Please note that when using an oven or microwave, the seeds will not only dry out, but also lightly fry. They become truly dried only in the sun.
You can also dry the seeds in a simple frying pan. Stirring constantly, fry them over low heat until cooked.
When using an oven or microwave, the seeds will not only dry, but also lightly toast
There are two ways to make salted sunflower seeds at home. Either sprinkle the seeds with table salt directly during drying, or soak the product in a saline solution in advance. To do this, dissolve 500 g of salt in 1 liter of water. Soaking time is from 6 to 36 hours, depending on the desired result (the longer the process, the more salty the final product will be). Experienced cooks recommend using the second method, as it allows the salt to penetrate inside the peel and improve the taste of the kernel.
Pumpkin
Pumpkin seeds, like sunflower seeds, can be bought in the store or extracted yourself from ripe vegetables. Carefully cut off the top of the pumpkin, remove the core and remove the seeds from the pulp. Rinse them under running water until they no longer stick to your fingers.
You can dry pumpkin seeds in several ways: in the oven, in the microwave, in an electric dryer, in a convection oven, or in the air. Preheat the oven to +80 °C (up to +100 °C if the seeds are large) and keep the reserves evenly laid out on a baking sheet in it for half an hour. It will take about 20 minutes to dehydrate pumpkin seeds in the microwave. maximum power). Pumpkin seeds are dried in an electric dryer for 1 hour at a temperature of +80 °C. On a special air fryer grid, the seeds will be cooked for 30 minutes at a temperature of +60 °C. Pumpkin seeds dry in the open air under the sun for about 5 hours.
To salt pumpkin seeds, lightly fry them already dried in a frying pan, sprinkling with the required amount of spices.
Linen
Flaxseeds are very beneficial for people following a vegetarian diet, as they contain a lot of fatty acids. You can dry them either in the sun for several hours or in the oven at medium temperature.
Sesame
Sesame seeds, rich in phosphorus and proteins, are dried according to the same rules as any other. Sesame seeds are widely used for preparing various main dishes (especially Japanese cuisine) and home baking.
The main oilseed crop in Ukraine is sunflower. Freshly harvested sunflower seeds have very low storage stability, especially at high humidity, temperature and contamination. When storing seeds, fats undergo chemical changes first, followed by protein substances.
High-oil sunflower seeds are reliably stored if their humidity does not exceed 7% and the temperature is reduced to 10°C or lower. At humidity above critical and a temperature of 2025°C, characteristic of freshly formed batches of sunflower seeds, rapid development of microorganisms begins in the seed mound, hydrolytic and oxidative processes proceed intensively, which leads to a rapid deterioration in the quality of sunflower seeds as oilseed raw materials. Even several hours of storing freshly harvested high-oil sunflower seeds with a moisture content above critical leads to massive self-heating and spoilage, which makes it impossible to obtain high-grade oil.
Self-heating of sunflower develops very quickly and leads to complete spoilage of the seeds, an increase in the acid number of the oil to 3035 mg KOH per 1 g of fat. Among the reasons for self-heating are contamination (when stored under the same conditions, the moisture content of organic impurities is almost 2 times higher than the moisture content of the seeds), as well as the presence of microorganisms in the seed mass, mainly non-spore-forming epiphytic bacteria and molds.
When a large amount of wet and raw sunflower is received in a short time, it is not always possible to dry it in a stream. In this regard, it is advisable to use various methods to increase the resistance of freshly harvested sunflower seeds, including active ventilation. Temporary storage periods and ventilation modes are established by the relevant instructions. If there are sunflower seeds that differ in oil content, batches of seeds are formed according to oil content groups. Approximate dates stable storage of high-oil sunflower seeds depending on their humidity and temperature, proposed by the Kuban branch of the All-Russia Research Institute of Plants, are given in table. 1.
For long-term storage before processing, sunflower seeds with a contamination level of no more than 2%, dried to critical humidity (67%) and cooled to low positive temperatures should be placed. The duration of storage under such conditions is 36 months, if the temperature of the dried seeds before storing or during the first 15 days of storage is reduced to 010°C.
Sunflower seeds with a moisture content below 12% awaiting drying can be temporarily placed in warehouses equipped with active ventilation units, but with a moisture content above 12% they must be dried immediately.
At grain receiving enterprises (GRE), drying is carried out in accordance with industry standards. normative document Instructions for drying food and feed grains, oat crops and operating grain dryers. Sunflower seeds for processing are dried, as a rule, to a moisture content of 78%, and those intended for long-term storage - to 67%. Before feeding the seeds into the shaft dryer, they must be cleaned of large impurities in a vortex cleaner or in a separator with the following set of sieves: receiving sieves with holes Ø1620 mm, sorting sieves with holes Ø1012 mm, discharge sieves with holes Ø1012 mm and sowing sieves with holes size 2.5x20 mm. Light impurities are separated in pneumatic separating channels by an air flow at a speed of 46 m/s.
Drying modes for sunflower seeds depend on their initial moisture content and drying method and are regulated by drying instructions. Higher limit values of the temperature of the drying agent and heating of sunflower seeds at in various ways drying in shaft direct-flow and recirculating dryers are given in table. 24.
The technological value of sunflower seeds is determined by its oil content. Therefore, it is important to maintain the quantity and quality of the oil. During the drying process, either synthesis or breakdown of fat components can occur. The direction of these transformations depends on the moisture content of the seeds, the temperature and duration of their heating. At optimal modes drying, the oil content in sunflower seeds increases. The accompanying substances contained in the seeds pass into the oil: phosphatites, carotenoids, sterols, waxy substances.
Since under these conditions sunflower seeds can be dried in dryers various types, let us briefly consider their features.
Drying sunflower seeds in mine grain dryers.
Up to 90% of harvested sunflower seeds are dried in mine grain dryers. High-moisture seeds in these units are subjected to double and sometimes triple drying, which disrupts the flow of processing, which significantly complicates working with newly received seeds. Due to the uneven movement of seeds across the cross-section of the shafts, when they are blown with a drying agent, a large uneven heating of the seeds is observed: near the walls of the shafts they move more slowly than in the middle, while the uneven heating reaches more than 10°C. If the seeds contain weeds, the mines may become clogged and often the dryer may catch fire. Therefore, drying seeds without first cleaning them is not allowed.
When starting the dryer, the temperature of the drying agent should be set to no higher than 80°C and then reach the recommended temperature (Table 24). If sunflower seeds contain more than 5% weed and oil impurities, the maximum permissible temperature of the drying agent should be reduced by 10°C in each zone. When drying sunflower seeds, it is necessary to monitor the constant loading of the above-mine bunkers, not allowing the level of the embankment to drop below 1 m. At least once every three days, it is necessary to empty the dryers of seeds, thoroughly clean them of debris and blow them out atmospheric air.
Of all shaft-type grain dryers, it is better to use twin dryers, for example DSP-32-OTx2, for drying sunflower seeds. They allow you to dry seeds in different ways technological schemes depending on the initial humidity and the required moisture removal. Thus, with a relatively low initial humidity (up to 14%), sunflower seeds can be dried in one pass using the drying-cooling scheme. Both grain dryers operate in parallel. When the seed moisture content is from 14 to 20%, it is advisable to sequentially pass the seeds through both dryers according to the drying-resting-drying-cooling scheme (the cooling zone fan of the first dryer is turned off). When the seed moisture content is above 20%, the cooling shaft of the first grain dryer can be used as a dryer by connecting it to the firebox.
It is necessary to pay attention to the fact that if the dryer throughput is insufficient, overheating of sunflower seeds may occur. So, according to data, even in temperature conditions of 80 and 145 ° C; 90 and 145°C with insufficient passage of seeds through the dryer, they were heated to temperatures of 62 and 58°C. Conversely, under more severe temperature conditions (120 and 140°C), sunflower seeds with an initial moisture content of 21.8% were dried to 8.6% at a throughput of 15.4 t/h and at the same time they were heated to a temperature of 45°C.
Modernization of dryers. The uneven heating of seeds along the horizontal section in the zone of maximum heating of seeds varies within a fairly wide range - from 40 to 70°C. Seeds have the highest heating temperature in the wall zones running parallel to the boxes, which leads to overheating of the seeds, their drying out and even burning. This is explained by the fact that in the wall areas the distance between the outer boxes and the wall of the dryer is approximately 2 times less than between the boxes. In addition, when seeds are loaded into the dryer, they self-sort. Lighter components flow to the walls of the dryer, which further reduces the speed of movement of sunflower seeds in the wall zone.
Therefore, in order to improve the operation of mine dryers and the quality of dried sunflower seeds, it is recommended to carry out a number of measures in advance. The wall rows of air distribution boxes are replaced with half-boxes and installed at a distance of 100115 mm from the walls. To prevent overheating of the seeds, a horizontal metal partition is installed above the divider of the over-drying bin located above the air distribution chamber. Taking into account the reduced flowability and low bulk density of sunflower seeds, loading gravity pipes Ø220 mm are replaced with pipes Ø300 mm and installed at an angle of at least 60°C. To reduce self-sorting of seeds, they are fed into the drying bunker through 45 gravity pipes.
Various options for the reconstruction of mine direct-flow grain dryers are also given in specialized literature.
Drying sunflower seeds in recirculating grain dryers
Compared to direct-flow grain dryers, recirculating grain dryers provide the ability to simultaneously dry seeds of different moisture content in one pass and have higher technical and economic indicators.
Drying sunflower seeds in recirculating dryers should be entrusted to the most experienced workers. In recirculating dryers with a heating chamber located above the heat-moisture exchanger, the level of sunflower seeds should be kept lower than usual (the distance from the lower edge of the heating chamber to the surface of the grain mound should be at least 1.2 m). The supply of recirculating sunflower seeds to the heating chamber must not be interrupted while the furnace is running.
The grain drying technology of recirculating grain dryers with heating chambers in a falling bed consists of alternating short-term heating (23 s) of a seed mixture in an upward flow of a drying agent at a temperature of 250350°C, resting the heated seed mixture, subsequent cooling and recirculation of most of the dried grain. During one drying cycle, a relatively small (about 2%) amount of moisture evaporates. Simultaneously with drying, the seeds are cleaned of impurities.
High-temperature drying of sunflower seeds in recirculating grain dryers has a beneficial effect on oil quality indicators. Thus, according to data, when seeds are heated in a dryer to 6070°C, the acid number decreases, and with more low temperatures heating (up to 50°C) - a slight increase in the acid number of the oil. However, the acid number of the oil decreases at temperatures above 70°C, and the decrease in this indicator is greater, the higher the heating temperature of the seeds. It should be noted, however, that at higher heating temperatures of seeds, an increase in injury occurs due to overdrying of the fruit shell. Sunflower seeds with damaged fruit shells are poorly stored and quickly deteriorate.
The disadvantages of recirculating grain dryers with heating chambers in the falling layer include their increased fire hazard. Ignition can occur at a drying agent temperature of 205°C or higher if a spark enters the heating chamber with oil dust accumulated on the walls.
Among recirculating grain dryers that do not have special heaters for heating seeds, it is advisable to use the A1-DSP-50 grain dryer from the Karlovsky Machine Plant (Poltava region). This dryer can also operate as a direct-flow dryer, if necessary, to remove up to 6% of moisture. This enterprise in recent years A number of new grain dryers of a similar design with a capacity of 10, 20 and 25 mt/h were released, providing continuous drying with good technical and economic performance indicators.
Modernization of dryers. To reduce the fire hazard of recirculating grain dryers when drying sunflower seeds, it is necessary: 1) to prevent the accumulation of oil dust in the heating chamber and to prevent sparks from entering the heating chamber from the furnace; 2) distribute the seeds evenly over the entire cross-section of the heating chamber at maximum load of the recirculation elevator. For this purpose, it is recommended to equip grain dryers with a fireproof heating chamber of variable cross-section with brake elements in the form of cones on flexible suspensions (in heating chambers with brake elements in the form of pipes, weld two steel strips from below along each pipe at an angle of 45 (one to one) and use a dual-circuit scheme cooling, install a spark arrester in the dryer furnace, and supply a drying agent with a temperature of 100 ± 10 ° C into the recirculation shaft, thus ensuring a recirculation-isothermal drying mode. The capacity of the heat and moisture exchanger should be designed for 1520 minutes of seeds being in it. Gravity pipes are installed under. an angle of 60°, and their diameter should be 25% larger than for cereal crops. The bottoms of diffusers and confusers for the drying agent in the heating chamber should be installed at an angle of 60°70°. All this allows to intensify the drying of sunflower seeds and ensure stable, stable drying. fireproof operation of the dryer.
It is noted that high-temperature drying of sunflower seeds from a humidity of 29.9% to 7% on a modernized grain dryer with double-circuit cooling at drying agent temperatures of 304310°C ensured heating of sunflower seeds in the range of 5861°C. At the same time, the acid number of the oil increased by 0.190.22 mg KOH, the efficiency of seed cleaning in the dryer was 5364%, the productivity of the grain dryer increased from 28 to 46.5 pl.t/h, and the cost of equivalent fuel decreased by 1.2 kg . Under such conditions, 6000 tons of seeds were dried and not a single case of fire in the dryer or waste in the bunker was observed.
Drying sunflower seeds in drum dryers.
To dry sunflower seeds in the oil and fat industry, drum dryers with differentiated drying modes are used, depending on the moisture content of the seeds. The temperature of the drying agent should be higher, the higher the seed moisture content. The big disadvantages of using drum dryers are partial cracking of the husks and collapsing of seeds, low moisture removal per pass through the dryer, and low productivity.
Drying of seeds in drum dryers occurs in an overflowing layer of seeds when it is blown with a drying agent. In drum dryers, the temperature of the drying agent, depending on the moisture content of the seeds and productivity, is maintained at 250350°C, at the exit from the dryer 5080°C. The average duration of stay of seeds in the dryer is 1417 minutes.
In a drum dryer, drying proceeds faster than in a shaft dryer, but the filling factor of the drum volume with seeds is 2025%, and therefore the amount of moisture evaporated in 1 m3 of drum space is less than in a shaft grain dryer.
Harsh drying modes and varying residence times of sunflower seeds in drum dryers cause uneven heating and drying, an increase in husks and the acid number of fat, increased consumption fuel.
Modernization of drum grain dryers is carried out according to various schemes. One of them is to change the internal drum fitting. The second allows you to organize transverse blowing of the seed layer (from bottom to top) with the formation of a fluidized layer. A method has also been proposed for drying sunflower seeds in an overflowing layer in a drum dryer with a channel attachment, which allows obtaining the necessary moisture removal in one pass at any initial humidity and significantly reduced damage to the seeds.
Drying sunflower seeds in ventilated bins.
For drying sunflower seeds, bunkers SZTs-1.5, BV-25, OBV-100, OBV-50, K-878, K-839 are used, equipped with active ventilation units and equipped with two-section electric air heaters (air heaters). At a relative humidity of 75 to 80%, only one of the heater sections can be turned on, and at more than 80%, the regulators connect both sections and they work simultaneously. Active drying of sunflower seeds in ventilated bunkers is possible using air heaters VPT-600, TAU-0.75, etc. In this case, a tarpaulin hose is connected to two or one bunker so that about 500 m3/h of drying agent per 1 ton of seeds.
The advantage of ventilated bunkers is their simplicity and accessibility. They do not require large capital investments and have long term services. The use of soft drying modes prevents seed injury, which is especially important for sunflower seeds.
The disadvantages include a long drying time, significant unevenness of drying in terms of moisture content between layers (the difference in the quality of seeds in terms of moisture content reaches 1.5-3.5%), low productivity. To eliminate these shortcomings when drying sunflower seeds in ventilated bins, two options are used.
In the first option, every 3.54.0 hours of drying (initial seed moisture 913%), the fan is stopped, and the seeds are moved in the same hopper by releasing them from the hopper within 1015 minutes and directing them into the same hopper. The drying process then continues. The second option uses two bunkers. The seeds are dried in the first bin for 2.53.5 hours, then moved to another bin, where drying is continued for 34 hours.
During post-harvest processing, sunflower seeds are injured. High-oil sunflower seeds are more susceptible to injury than low-oil sunflower seeds, since their shell is thinner and less durable. The degree of injury to high-oil sunflower seeds during movement on various equipment has been established. Sunflower seeds are most damaged at the turns of gravity pipes, elevators and augers. Thus, when passing a turn in a gravity pipe at an angle of 10° (before the turn, the length of the pipe is 7 m), the increase in injured seeds was 0.20.4% of the total mass of sunflower seeds, when transported in elevators with a belt speed of 2.2 2.5 m/s from 0.6 to 3.0%, in the auger from 1.2 to 6.0%. In this regard, when drying sunflower seeds in recirculating grain dryers, it is necessary to: strive, if possible, to reduce the number of recirculation cycles by switching the dryers to recirculation-isothermal drying, eliminate sharp turns in pipelines, soften the shock when loading the elevator; feed the seeds along the elevator belt at a speed of no more than 2.0 m/s, install dampers when dropping seeds from a great height.
Table 1.
| Seed moisture, % | Air temperature, °C | |||
| 20 | 10 | 1 | -10 | |
| 8 | 1,5 | 4,5 | More than 6 | More than 6 |
| 10 | 0 | 3,0 | The same | The same |
| 12 | 0 | 1,5 | 5 | The same |
| 14 | 0 | 0,5 | 3,3 | The same |
| 16 | 0 | 0 | 2 | The same |
| 18 | 0 | 0 | 1,3 | 6 |
| 20 | 0 | 0 | 0,5 | 4,5 |
| 22 | 0 | 0 | 0 | 3 |
| 24 | 0 | 0 | 0 | 2 |
Table 2.
| Initial seed moisture, % | Passing seeds through a dryer | Limit temperatures, °C | |||
| heating seeds | drying agent in drying mode | ||||
| single-stage | two-stage | ||||
| first zone | second zone | ||||
| Up to 15 | 55 | 120 | 120 | 135 | |
| Up to 20 | 55 | 115 | 115 | 130 | |
| More than 20 | First | 55 | 110 | 110 | 125 |
| Second | 55 | 115 | 115 | 130 | |
Table 3.
Note. In recirculating dryers with a cascade heater (dryers A1-UZM, A1-USSh and reconstructed DSP-32-OT with the U1-UKZ-50 set), the temperature of the drying agent at the inlet to the heater should not exceed 200°C.
Drying sunflower seeds
This is the most critical operation, which significantly affects the yield and quality of the product. During drying, biological and biochemical transformations of simple chemicals into complex ones take place, proteins and carbohydrates accumulate (turn into fats), physical parameters and quality indicators change.
The drying process has its own general technological rules, as well as specific ones related to the characteristics of a particular crop and the design of the grain dryer. Common ones include: selection of batches with the same humidity; cleaning freshly harvested mass from coarse impurities; observing temperature and ventilation conditions; completion of drying at optimal humidity; cooling the dried mass. When drying sunflowers, you need to take into account the anatomical structure of the seed and physical properties its individual parts. Thus, the seed kernel and the fruit shell (husk) have different hygroscopicity, therefore differently evaporate moisture.
The moisture evaporators are also affected by a strong shell layer, as a result of which during drying the peripheral part of the seed (husk) dries faster, becomes denser and resists the evaporation of moisture from the inner part (kernel).
To maintain moisture evaporation at a high level, use various modes drying: with preheating of seeds; alternating periods of heating and cooling; mild temperatures of heating the seed and drying agent depending on the humidity of the sunflower.
Sunflower seeds for food purposes are dried in direct-flow and recirculating dryers under the following conditions: keep the seeds in a drying hopper at least 1 m deep; clean the dryer of debris and blow it with atmospheric air at least once every three days, start drying at a temperature not exceeding 80 ° C, if there are weeds and oilseed impurities in the seeds (more than 5%), reduce the temperature of the drying agent by 10 ° C at each zone and at 20 °C - in a heating chamber with a falling layer of seeds. In recirculating dryers with a heating chamber installed above a heat exchanger, the seed level is maintained in such a way that the distance from the bottom spring of the chamber to the surface of the embankment is at least 1.2 m, while not allowing a reduction in the supply of recirculating seed to the heating chamber when the furnace is running. .
Farmers - agricultural producers of relatively small volumes of grain - can also practice thermoradiation (solar-air) drying. Such sunflower drying begins almost at the harvesting stage, during the placement of grain masses on sites, during cleaning, during loading and unloading with belt loaders or front loaders. The natural drying method is especially effective in conditions of dry and warm weather, which is currently observed in the autumn period. In a number of farms, freshly harvested sunflower seeds with a moisture content of 10-12% are placed in the form of piles 0.8-1 m high with an orientation from south-east to northwest for better heating and ventilation. The wet seeds are scattered in a thin layer (15-20 cm), mixed regularly, and at night they are piled into piles and, if necessary, covered. As experience shows, due to natural drying, the moisture content of seeds per day decreases by 1.5-2%, depending on the temperature and intensity of ventilation.
Sunflower seeds also dry out by passing them through loaders, cleaning machines, and grain separators. After passing through various mechanisms, humidity can decrease by 0.5-0.8%.
Drying, especially thermal in grain dryers, should end when a certain moisture content of the grain (seeds) is reached, depending on the direction of use.
Agrotechnical requirements
Industrial raw materials. For long-term and safe storage, sunflower seeds must be dried to a moisture content of 6-7%. Seeds with a moisture content of 16 percent or more must be dried to a moisture content of 12% within one day, and with a moisture content of up to 16% within two days. Storage of seeds with a moisture content of 10-12% is allowed for 8-9 days.
Before drying, all drying equipment must be cleaned of debris and seeds of other crops. Damage to sunflower seeds by the working parts of drying equipment should not exceed 1%.
Heating of achenes when drying in a moving layer can be no more than 50-60 ° C, on drum and pneumatic drum - 55-85 ° C, and when drying in a fixed layer - 45-55 ° C. Removal of moisture in one pass through continuous dryers 4-12%, and periodic (ventilated bunkers and floor devices with air heating) up to 2% per hour. Thermal conditions for drying sunflower seeds are presented in Table 58.
Seed material. For drying seed material, the same drying devices, as for industrial raw materials. The same requirements for drying the initial heap remain.
The seed material must be dried to a moisture content of 6-7%. Moisture removal during drying in a moving layer is 3-4%, and in a fixed layer 0.6-1% per hour in one pass. The thermal drying mode is carried out according to Table 57. It is impossible to dry seed material in ABM type units, since sufficient uniformity of seed heating is not ensured and their germination deteriorates.
Seed drying units
For drying sunflower seeds, mine dryers SZSh-8, SZSh-16, SZSh-16R are used, included in the grain cleaning complexes KZS-10, KZS-20Sh, KZS-25Sh, KZS-40Sh, drum dryers - SZST-8, pneumatic drum SB-1, 5, sections of ventilated bunkers OBV-50, OBV-100, K-878 (GDR), equipped with air heaters of the VPT-600 type, floor devices with air heaters.
Mine dryers provide a soft drying mode for both industrial raw materials and seed material. Technological lines of KZS complexes make it possible to organize the continuity and flow of the technological process of processing wet seeds.
Drum and pneumatic drum dryers mainly used for drying industrial raw materials. Drums can also be used for drying seed material.
Settings periodic action(active ventilation bunkers, floor devices) are used for cooling, temporary storage and drying of industrial raw materials and seed material. Active aeration bunkers are also effective in technological complexes of mine dryers for cooling and storing seeds.
Technological scheme for drying seeds of the KZS-25Sh grain cleaning complex. The drying compartments are loaded from the temporary storage bins of the OP-50 pre-cleaning department after cleaning the seeds using the MPO-50 pre-cleaning machine. After drying, the material enters the reserve and dry grain bunker, and from it for final cleaning ZVS-20A.
Temporary storage bunkers (260 m3) are equipped with level and temperature sensors and an aeration system.
Seeds with a moisture content of 12-14% are dried with parallel operation of the mines. Air (coolant), heated to 140-150° C when drying industrial raw materials and up to 60-80° C for seed material, enters from the combustion unit with the help of fans through the supply boxes into the layer of seeds, heats them and removes moisture. The amount of removal is regulated by the speed of movement of the seeds in the shaft using the shaft unloading device.
The dried seeds enter the lower bunkers and then into the elevator, which feeds them into the cooling column, from which they are sent to the reserve and dry grain bunker.
If the moisture content of the achenes is more than 14%, they are dried during sequential operation of the mines. The pre-cleaned heap enters the first drying chamber(mine) and dried in it, as noted above. Dried and cooled seeds are fed by elevator into the second drying chamber, from where they enter the cooling column and then into the reserve and dry grain bunker, and from there into final cleaning or procurement points.
The technological process of drying seeds on grain cleaning complexes KZS-20Sh and KZS-40Sh is similar to drying on the KZS-25Sh complex. The ZAV-25 unit in combination with the SZPB-8 dryer forms the KZS-25B complex. Its operation scheme is similar to KZS-25Sh.
Technological diagram of the compartments of ventilated bunkers OBV-50, OBV-100. Pre-cleaned seeds are fed through a grain pipeline system into the loading elevator of the compartment, which is lifted up and sent through a distributor to the bunker. Before filling the hopper, the floating air valve is raised. After filling the bunker, the achenes are moved using a bucket elevator for 3-5 minutes from the bottom tier of the bunker to the top. To eliminate compacted areas, the air valve is lowered and the cooling or drying system is turned on. Dried seeds are unloaded from the bunker for re-cleaning and drying or taken to procurement points.
Preparing drying equipment for operation
Mine dryers. Clean shafts, cooling columns, transport mechanisms and other devices, thoroughly clean them of debris, dust, and seeds of other crops. They check the operation of valve flaps, transport mechanisms, combustion devices, equipment for controlling the operation of mechanisms and monitoring.
To reduce the crushing of achenes, reduce the speed of the working parts of the elevators from 3.3 to 1.6 m/s, replacing the drive motor with a rotation speed of 1420 s-1 with 950 s-1, install a pulley with a diameter of 120 mm on it, and an asterisk on the counter-drive shaft z=10. To ensure that the productivity of the elevator does not decrease, the buckets on its belt are installed in increments of 160 mm.
The installation angle of the loading and transfer seed pipes is adjusted to 45-50 °, increasing the height of the elevator by 1-1.2 m.
If necessary, individual components and mechanisms are repaired or replaced. At idle, check the joint operation of all components and mechanisms of the dryer.
Bunkers of compartments OBV-50, OBV-100. When preparing bunkers BV-1,2 and BV-25 for ventilation and soft-mode drying of sunflower seeds, they are cleaned of grain residues of other crops, inspected and checked the operation of elevators, fans, electric heaters, and the cable-block system of control station bunkers.
To prevent scattering of seeds beyond the receiving device of the bunkers, according to the recommendation of VNIIMK, increase the height of its ring by 300 mm.
To prevent arching of seeds during unloading, the cone of the hopper is cut so that the diameter of the hole at the cut point is 170-200 mm. A new gate of increased size is welded to the cut site.
To dry seeds with cold air, the bunkers are equipped with high-performance fans.
To increase the productivity of bunkers in the mode of soft drying with heated air, instead of electric heaters, air heaters of the VPT-600 type are installed (one air heater for two bunkers), connecting them with one air duct.
Operation of drying equipment
Dryer SZSh-8, SZSh-16, SZSh-16R. The moisture content of the sunflower heap is determined and the drying mode and technology (parallel or sequential operation of the mines) is established.
The loading devices are switched on, the dampers are smoothly opened and the initial heap is fed into them. The shafts are loaded with seeds and the dryer is started to warm up. Warm-up duration is 25-30 minutes when drying industrial raw materials and 10-15 minutes when drying seed material.
The temperature of the coolant in the “warm-up” mode is set 20° below that provided by the drying mode (see Table 57). When warmed up after 8-10 minutes, the seeds are released from the shaft within 1-2 minutes and sent through cooling columns to a raw seed elevator for re-feeding into the shaft.
After warming up, the fan throttle valves are opened, the dry seed elevators, elevators and fans of the cooling columns are turned on. The first portion of seeds from the bottom of the chambers is sent for drying within 20-25 minutes, and then the dryer is switched to the “drying” mode. In this case, dry seeds are removed from the shafts by a loading device and sent to cooling columns, then to a reserve and storage bunker or for re-cleaning.
During operation, monitor the serviceability of the dryer components and mechanisms, temperature conditions. If the coolant temperature is low, then increase fuel consumption by increasing the pressure in the system, and vice versa. At a high temperature of the achenes at the outlet, the productivity of the mine unloading devices is increased by changing the vibration amplitudes of the carriage, or the air flow is increased by opening the throttle valves of the suction fan boxes.
Dryer SZSB-8. Before drying, the moisture content of the heap to be processed is determined. Based on its humidity and purpose, the drying mode is set.
Light the firebox and warm up the drying drum for 10-15 minutes, bringing the temperature at the drum outlet to 20-25° C below the set thermal regime. At the end of warming up, turn on the elevator, smoothly open the valve of the receiving toe of the elevator to feed seeds into the drying drum. When they pass the drum and begin to flow into the discharge elevator, the temperature of the coolant is raised to the value prescribed by the drying mode.
During operation, carefully monitor all components and mechanisms of the dryer and temperature conditions. The drying mode is specified by the temperature of the coolant and the heating temperature of the seeds at the outlet of the drying drum, which should not exceed 65° C for industrial raw materials and 30-45° C for seed material. If the seeds overheat, the supply of the initial heap to the drying drum is increased. If this is not enough, then reduce the temperature of the coolant. The maximum amount of heap should enter the drum, but so that the seeds do not spill onto the flashing valve. If there is insufficient moisture removal, the coolant temperature is increased or the exhaust pipe dampers are opened to the maximum. The seeds coming out of the drying drum should be clean and free of smoke and fuel odors. Humidity samples are taken: the first after 0.5 hours, and subsequently - at least after 3 hours.
Active ventilation bunkers. Based on the humidity and purpose of the heap, the drying mode and the order of moving the seeds into a free bin are established.
Before loading the hopper, the unloading gate is closed and the valve is raised to the highest position. Having loaded the hopper to the required level, the valve is lowered to a position in which its upper end is 150-250 mm below the seed level at the air distribution pipe. After loading the achenes, the surface of the embankment should have the shape of a regular cone with an angle of repose of 40-45°. If such a surface has not been formed, then it should be formed manually, since if the valve is installed incorrectly, an air breakthrough is possible.
After filling the bunker, the seeds are poured from bottom to top within 3-5 minutes to eliminate compacted areas and create conditions for uniform drying. This operation should also be done during the drying process of the wet heap, every 3-4 hours of drying for 0.1-0.2 hours.
During drying, the height (level) of the seeds in the hopper decreases. Therefore, periodically (every 3-4 hours) you should adjust the position of the valve, which is lowered or raised when the fan is turned off.
The drying process is controlled automatically by installing VDK humidity regulators in the electrical control circuit of the fan and heater. One regulator is set to operate at a relative humidity of 75, the second - more than 80%. When the relative humidity is more than 75%, one heater is turned on, and when the humidity is more than 80%, both heaters are turned on.
Samples to determine the temperature of the seeds and determine their moisture content are taken through a sampler at least 3-4 times per shift.
