Classifications

• • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
  • F26—DRYING
  • F26B—DRYING SOLID MATERIALS OR OBJECTS BY REMOVING LIQUID THEREFROM
  • F26B25/00—Details of general application not covered by group F26B21/00 or F26B23/00
  • F26B25/22—Controlling the drying process in dependence on liquid content of solid materials or objects
• • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
  • F26—DRYING
  • F26B—DRYING SOLID MATERIALS OR OBJECTS BY REMOVING LIQUID THEREFROM
  • F26B17/00—Machines or apparatus for drying materials in loose, plastic, or fluidised form, e.g. granules, staple fibres, with progressive movement
  • F26B17/12—Machines or apparatus for drying materials in loose, plastic, or fluidised form, e.g. granules, staple fibres, with progressive movement with movement performed solely by gravity, i.e. the material moving through a substantially vertical drying enclosure, e.g. shaft
  • F26B17/122—Machines or apparatus for drying materials in loose, plastic, or fluidised form, e.g. granules, staple fibres, with progressive movement with movement performed solely by gravity, i.e. the material moving through a substantially vertical drying enclosure, e.g. shaft the material moving through a cross-flow of drying gas; the drying enclosure, e.g. shaft, consisting of substantially vertical, perforated walls
• • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
  • Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
  • Y02P—CLIMATE CHANGE MITIGATION TECHNOLOGIES IN THE PRODUCTION OR PROCESSING OF GOODS
  • Y02P70/00—Climate change mitigation technologies in the production process for final industrial or consumer products
  • Y02P70/10—Greenhouse gas [GHG] capture, material saving, heat recovery or other energy efficient measures, e.g. motor control, characterised by manufacturing processes, e.g. for rolling metal or metal working

Definitions

• the invention relates to a method for energy-saving drying, in particular of granular, agricultural or other products containing constant and superficial moisture, with constant output, in which the material to be dried is passed into contact with a heat-carrying drying medium as it passes through the drying room, then the vapor-laden drying medium Immediately or after partial use of its heat content is discharged into the open air and the dry matter freed from its moisture content in a pre-aerated degree is fed for further processing or use.
• the invention relates to a device for carrying out the above-mentioned method, which includes a dryer room with moist material supply and emptying opening, a drying medium pressure fan connected via blowing-in and optionally a drying medium connected via suction channel Has extraction fan, a drying medium heater being inserted before or after the pressure fan.
• the substance-bound or surface-adhering liquid is removed by evaporation in dryers.
• the amount of heat required for evaporation is supplied directly to the material to be dried in the dryer by radiation, conduction or convection or by means of a heat-carrying - mostly gaseous - substance.
• the evaporated vapors are then discharged into the environment by the heat-carrying medium itself.
• the dry material, freed from its liquid content to a predetermined degree, is otherwise used for further processing or use.
• Loss sources are all the amounts of heat that are used to. first come off over the outer surface of the device, second with the dried material, third with the moisture converted into vapors and with the drying medium carrying them.
• the object of the invention is to eliminate all of these disadvantages and at the same time to ensure a uniform quality of the dried goods.
• the invention is based on the physical phenomenon that the intensity of the removal of liquid by evaporation changes significantly in the course of the drying process in the individual goods to be dried.
• the preheating of the moist material takes place, since preheating to a temperature of 60-120 ° C. is required in the devices, which mostly work at atmospheric pressure, for the onset of rapid evaporation of water.
• the moisture that adheres to the surface of the material or is present in the vicinity begins to escape.
• the evaporation rate is high and, insofar as the design of the dryer allows intensive heat input, significant amounts of moisture can be removed almost uniformly in a short time.
• the object is achieved in the sense of the invention in such a way that the hot, low-moisture drying medium emerging from the dryer section of the mass transport of the bound moisture is returned to the sections of the preheating and intensive drying to the beginning of the dryer room. At the same time, other heating of these sections is switched off. As a result, the significant heat loss that occurs when leaving the section of mass transfer of the bound moisture can be recovered without the use of a special heat utilization device. Only the residual heat content of the drying medium emerging from the sections of preheating and intensive drying occurs as a loss.
• This air flow which is warmer than the environment - the absolute moisture content of which is the same as that of the ambient air - can be used to advantage in the drying process by simply mixing it with the hot air flow entering the section of the mass transport of the bound moisture or as combustion air in the combustion chamber of the dryer is fed.
• the moisture content of the goods to be dried is within wide limits. With all dryer systems, this leads to fluctuations in the moisture content in the end product, which is why the flow rate or the temperature of the drying, i.e. the intensity of the heat source needs to be changed.
• the uniformity of the quality of the dried goods is ensured in the sense of the invention in such a way that the moisture contents of the moisture guire entering the dryer room and of the emerging dry goods are measured and, with the differential analog signal thus obtained, the throughput quantity of the goods to be dried, possibly the Heating of the drying medium is controlled.
• the throughput of the material should preferably be modulated in order to keep the amount of moisture removed constant over time.
• This procedure has the outstanding advantage, for example, in the case of gravitational flow of the material, that quantity control of the energy source used (oil, gas, steam) is practically unnecessary and the heating device can therefore be designed very simply.
• the use of the invention means that there is no need to replace or significantly redesign the firing device. This enables the task to be controlled by controlling a simple flat sheet pusher used in the gravitational flow of the goods solve by the differential-analog signal described above in a simple manner.
• the heating requirement of a drying system operated in the manner described theoretically fluctuates solely as a function of temperature changes in the ambient air.
• the device according to the invention is used, which was also of the type mentioned at the outset, in particular by suitable modification of existing drying plants
• Tower dryers with gravitational flow - can be realized. It is characteristic of the facility that its dryer room is divided into a section of the preheating and intensive drying, a section of the mass transfer of the bound moisture and a cooling section, the section of the preheating and intensive drying is connected to that of the mass transport of the bound moisture through a transfer channel Moisture sensors are installed in the supply of moist material and in the vicinity of the emptying opening, the differential-analog signals of which are fed to the position unit of the intensity of the emptying via transmitters.
• the adjusting unit for the intensity of the emptying contains a flat slide arranged at the emptying opening, the signals from the moisture sensors being transmitted via e.g. Transmitter are fed to the solenoid valves of a cylinder operating this flat slide valve.
• the separating plate used between the section of the preheating and intensive drying and the section of the mass transfer of the bound moisture can be adjusted depending on the desired ratio of these sections and the one arranged when the material to be dried is supplied
• Moisture sensor is connected in an actuating manner to the actuating unit of this separating plate via the TraisaLtter.
• the signals from the moisture sensors can be fed to the memory of a microprocessor control.
• the heating device switched on before or after the pressure fan consists of an oil or gas burner, which is controlled by a temperature sensor arranged in the blowing channel of the pressure fan.
• the pressure side of the cooling fan of the cooling section is expediently connected to the combustion chamber of the oil or gas burner.
• the pressure side of the cooling fan of the cooling section is advantageously connected to the sinus channel of the drying medium pressure fan.
• the device has a drying medium suction fan, the discharge duct of which is connected to a discharge pocket connected to the dryer space section of the preheating and intensive drying.
• FIG. 1 illustrates the drying characteristics of corn kernels with the entry of the individual sections of the drying process
• FIG. 2 shows a tower dryer designed in the sense of the invention for granular agricultural products in the basic scheme.
• the material to be dried for example maize kernel, enters via the moist material feed 1, the moisture content of which is detected by the moisture sensor 2.
• the measured value is stored in the memory of a microprocessor control in order to be electronically available at all times during the drying process.
• the corn kernels continuously pass through sections I and II, where the preheating and the intensive drying at a constant speed according to FIG. 1 take place. Knowing the parameters of the material participating in the drying process, the depth of the hodulation of the material flow can be determined, for example, using a microprocessor controller with the aid of mathematical formulas and diagrams empirically recorded for the dryer.
• the control variables determined according to the empirically recorded characteristic curve are corrected in the event of a deviation.
• the signal generated in this way is used as a pulse to control the solenoid valves 4 and 5, which control the inflow of hydraulic oil, for example, into the working cylinder 6 up to the mass caused by the differential analog signal.
• the emptying opening 8 is opened or closed as far as required by the predetermined moisture content of the emerging grain material by the flat slide 7. In this way, a flow of material is automatically set in the dryer, which guarantees the optimal operation of the entire system.
• the position of the separating plate 12 can be changed, as a result of which the delimitation of sections II and III is also changed.
• the pressure side of the cooling fan 9 of the cooling section H is connected to the injection duct 17 of the pressure fan 10.
• the performance of the oil burner 18 ' is controlled by the temperature sensor 11 arranged in the blowing duct 17 of the pressure fan 10. Since the value of the heat removal in the cooling section H, depending on the throughput of the material, is only slightly influenced by the temperature of the outside air.
• the temperature of the drying medium entering section III - the flue gas cooling air or ambient air - can be kept practically constant by the temperature sensor 11.
• the inflow of the drying medium takes place through the surface between the partition plate 12 and the cooling section H.
• the drying medium leaving the section III goes back through the transfer duct 13 to the sections I and II.
• the duct 15 leads the already cooled and vapor-saturated drying medium to the suction fan 16, from where it exits into the open air.
• a device for collecting and discharging waste, which is to be used as required, is shown. During the drying process, dust and / or other solid parts of matter separate from the goods to be dried, the collection or removal of which must be ensured by using elements known per se.
• the position of the partition plate 12 is changed by the signal emanating from the moisture sensor 2. if the moisture content decreases, sections I and II become shorter; if this increases, sections I and II become longer.
• the relationship between moisture content and section length is determined by the properties of the material to be dried and determined for the individual material by measurement (see Fig. 1).
• the goods to be dried can also be moved, for example, by means of a chute, conveyor belt, scraper conveyor or other conveyors.
• the differential analog signal controls, for example, the work of the engine.
• the thermal energy k-ann instead of oil firing also z.3. Natural gas, steam, thermal oil, flue gases from agricultural waste, coal and peat firing can be supplied.
• the task is to dry a throughput of 15 t / h corn kernel with a moisture content of 32% to a residual moisture content of 14%.
• Section III is supplied with about 120,000 kg / h of drying medium, of which about 40,000 kg / h comes from the cooling section.

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• Engineering & Computer Science (AREA)
• Mechanical Engineering (AREA)
• General Engineering & Computer Science (AREA)
• Drying Of Solid Materials (AREA)

Applications Claiming Priority (2)

Publications (2)

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Family Applications (1)

Country Status (6)

Families Citing this family (9)

Citations (8)

Family Cites Families (7)

• 1981
  • 1981-10-21 HU HU813071A patent/HU183005B/hu not_active IP Right Cessation
• 1982
  • 1982-10-18 WO PCT/HU1982/000053 patent/WO1983001502A1/de not_active Ceased
  • 1982-10-18 EP EP19820903054 patent/EP0091451A4/fr not_active Withdrawn
  • 1982-10-18 US US06/513,116 patent/US4555858A/en not_active Expired - Fee Related
  • 1982-10-21 PL PL23868782A patent/PL238687A1/xx unknown
  • 1982-10-21 DD DD82244189A patent/DD204305A5/de unknown

Patent Citations (8)

Non-Patent Citations (1)

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