RU2174659C2 - Fluidized bed grain drying apparatus - Google Patents

Abstract

FIELD: agriculture. SUBSTANCE: apparatus has drying chamber connected with feeding hopper, intermediate hopper, discharge hopper, gas supplying (delivery) box, gas discharging (suction) box, first gas distributing grid for gas supplying box, second gas distributing grid for gas discharging box, and conveyor with scrapers. Gas distributing grids also serve as tables for conveying grain by scrapers in drying chamber and in gas discharging box. Scrapers arranged in the vicinity of drying chamber outlet end and gas discharging box are enclosed in tunnels and adapted to form closures of conveyed grain. Apparatus allows power consumption for drying process in fluidized bed to be reduced due to recovery of part of heat energy by reclaiming air heat produced in the process of grain cooling. Apparatus is used for drying seed and food grain. EFFECT: increased efficiency, wider operational capabilities and enhanced reliability in operation. 2 cl, 2 dwg

Description

 The invention relates to the drying of grain in a fluidized bed and can be used in agriculture for drying seed and food grain.

 Known installations for drying grain in a fluidized bed (for example, A. V. Golubkovich and others. Drying of high moisture seeds and grain. Rosagropromizdat, M., 1991, p. 50-54). The installation includes a drying chamber, loading and unloading bins, a gas distribution grill through which air is supplied by a blower fan, and a furnace for heating air. After drying, the grain is fed into a special cooling column or the drying process is carried out discretely, alternating the supply of hot and cold air to the local fluidized bed.

 A disadvantage of the known installation for drying grain in a fluidized bed is a constructive limitation of the possibility of intensifying the drying process of grain to possible scientifically substantiated limits. This limitation is due to the following. The fluidized bed moves along the sieve unevenly - grains with a lower specific gravity move to the discharge hole faster than those whose specific gravity is larger. Part of the grains located at the side walls also lags behind. In this regard, it is necessary to significantly reduce the possible allowable limits of intensification of grain drying.

 Also known installation for drying polydisperse materials in a fluidized bed (AS USSR 1260649, CL F 26 B 17/10, publ. 1986), which is the prototype of the claimed technical solution. The prototype installation comprises a drying chamber with a loading hopper and two discharge hoppers, a gas distribution grid located in the chamber and a closed scraper conveyor interacting with one branch of the gas distribution grid, and a gas supply box located between the conveyor branches. The lower branch of the conveyor is placed in a tunnel bounded on one side by a box and connected to both discharge hoppers, and the discharge section of the upper branch is also enclosed in a tunnel with the formation of a shutter from the dried material. The installation of the prototype in the case of its use for drying grain solves the problem of increasing the uniformity of drying, and therefore less limits the possibility of intensifying the process.

 However, the disadvantage of the installation of the prototype is the high energy intensity of the process when using it for drying grain, which is due to the fact that the heat spent on drying is completely dissipated in the surrounding space. In addition, when using the prototype for drying grain, additional plants are needed for cooling the grain, which increases the metal consumption of the drying plant as a whole.

 The objective of the proposed technical solution is to reduce the energy intensity of the drying process of grain in the fluidized bed by recovering part of the thermal energy spent on drying by using the heat of the air exhausted during cooling of the grain.

 The problem is solved due to the fact that the installation for drying grain in a fluidized bed, containing a drying chamber with loading and unloading bins, a gas distribution grid placed in the chamber and a closed scraper conveyor interacting with the gas distribution grid, and a gas supply box, while the discharge sections of the conveyor are enclosed in tunnels with the formation of a shutter of dried grain, it is additionally equipped with a gas outlet box located under the gas supply and a second gas distribution grill, o razuyuschey bottom wall vent duct, and the lower branch conveyor is arranged to interact with a second gas distribution grille. In addition, the installation is equipped with an intermediate hopper.

 The claimed technical solution differs from the prototype in that the installation is additionally equipped with a gas outlet located below the gas supply and a second gas distribution grid forming the lower wall of the gas exhaust duct, and the lower branch of the scraper conveyor is installed with the possibility of interaction with the second gas distribution grid. In addition, the installation is equipped with an intermediate hopper.

 The use of the lower branch of the scraper conveyor for cooling grain allows you to combine in one installation the operation of drying the grain with the operation of its cooling. This allows you to expand the functionality of the installation and reduce energy consumption for drying the grain, since the air enters the heat generator for heating already heated from the cooling part of the dryer chamber. Thus, the achieved technical result is expressed in the fact that a dryer is created in which, without complicating the design and increasing the metal and material consumption, the grain is cooled and the heat of the heated grain is used in the drying process.

 Experimental studies show that the dryer, made according to the claimed technical solution, allows you to save 6-10% of the fuel spent (burned in the heat generator) for heating the air to dry the grain. Thus, the inventive dryer allows, without complicating the design, to perform grain cooling, due to the use of the lower branch of the scraper conveyor, not only for transporting grain, but also for cooling it. Due to the combination of functions by the nodes of the dryer, it is possible to reduce the metal consumption of the structure as a whole.

 In FIG. 1 schematically shows the installation, a longitudinal section. In FIG. 2 is a section AA in FIG. 1.

 The installation comprises a drying chamber 1 connected to a loading hopper 2, an intermediate hopper 3, an unloading hopper 4, a gas supply (discharge) duct 5, a gas exhaust (suction) duct 6, a gas distribution grill 7 of a gas supply duct 5, a second gas distribution grill 8 of a gas exhaust duct 6, a conveyor 9 with scrapers 10. Gas distribution grids 7 and 8 are simultaneously tables for transporting grain conveyor 9 by scrapers 10 in the drying chamber 1 and in the gas outlet box 6. Scrapers 9 in the exit zones yl chamber 1 and vent duct 6 enclosed in the tunnels 11 and 12 and form the gates of the transported grain.

 Installation works as follows.

 The initial wet grain from the loading hopper 2 with scrapers 10 of the upper branch of the conveyor 9 is sent to the drying chamber 1 to the gas distribution grid 7, through which hot air enters the chamber 1 from the gas supply discharge duct 5. Under its action, the grain in the drying chamber 1 passes into a fluidized state and is intensively dried in a fluidized bed. When leaving the chamber 1, the grain is transported by conveyors 9 to the tunnel 11 by the scrapers 10. In this tunnel 11, the grain forms a gate, and hot air does not exit the drying chamber 1. From the tunnel 11, the grain enters the intermediate hopper 3, where it is captured by the scrapers 10 and through the tunnel 12 enters the gas distribution grill 8 of the exhaust duct suction duct 6. Air is sucked through a layer of grain. In this case, the grain is cooled, and the air is heated. Grain is transported by scrapers 10 to the unloading hopper 4, and again passing through the tunnel 12, the dried and cooled grain is unloaded from the plant.

 An example of a specific installation.

 An experimental sample of the installation for drying grain in a fluidized bed according to the claimed design. The scraper conveyor has a length of 8 m and a scraper width of 300 mm. Under the lower and upper branches of the conveyor, air distribution grilles are installed in the form of lattice bottoms, respectively, of the air supply and air exhaust ducts with 2.5 mm openings. The air duct is connected to the air heating chamber. Air heating is carried out by a heat generator TG-1,5. The mass of the dryer is 300 kg. The conveyor speed is 0.01 m / s; the entire drying and cooling process takes about 30 minutes. The height of the fluidized bed was 120 mm. Productivity when drying seed grain is 1 t / h.

Claims (2)

 1. Installation for drying grain in a fluidized bed, containing a drying chamber with loading and unloading bins, a gas distribution grid placed in the chamber and a closed scraper conveyor interacting with the gas distribution grid, and a gas supply duct, wherein the discharge sections of the conveyor are enclosed in tunnels to form a shutter from the dried grain, characterized in that the installation is additionally equipped with a gas outlet box located under the gas supply, and a second gas distribution grill, o forming the bottom wall of the exhaust duct, and the lower branch of the scraper conveyor is installed with the possibility of interaction with the second gas distribution grill.  2. Installation according to claim 1, characterized in that it is additionally equipped with an intermediate hopper.

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