RU2727521C1 - Energy-saving shaft drier for grain crops - Google Patents

Abstract

FIELD: agriculture.SUBSTANCE: invention relates to agriculture and serves for drying grain crops, as well as for dehydration of other similar products and granulated materials. Said purpose is achieved by using energy-saving shaft drier for grain crops, comprising housing, mesh cylinders, dense bulk layer of grain material, heat carrier supply pipe, sector feeder, wet grain loading pipe and waste heat carrier outlet pipe, it differs from known designs in that it is equipped with internal separation cylinder, movable control cylinder and movable ring for the purpose of energy saving for more complete development of heat carrier.EFFECT: high degree of coolant development by temperature to increase efficiency of dryer.1 cl, 1 dwg

Description

The invention relates to the field of agriculture and is used for drying grain crops, as well as for dehydrating other similar products and granular materials. The method of energy-saving drying of grain crops includes feeding the material to be dried from top to bottom and blowing a heat carrier through the material to be dried. Part of the heat carrier spent in the drying zone is fed to the upper zone of the dryer for preheating the incoming granular material in counterflow mode. The technical result is an increase in the degree of working out the coolant in temperature in order to increase the economic performance of the dryer.

The known method of high-temperature drying of grain (Okun GS, Chizhikov. AG Trends in the development of technology and technical means of drying grain. -M .: VNIITEIagroprom, 1987. C. 6). Drying is carried out by feeding the material from top to bottom, and the heat carrier is supplied from the inside to the outside. This method allows realizing a high-temperature drying mode and increasing the uniformity of drying due to the circulation of grain in the drying chamber.

However, part of the layer, as it dries, can be separated from the main layer and dumped into the receiving hopper, and in the middle and lower parts, with thin layers of the material to be dried, the potential of the drying agent is also not fully utilized. In addition, stagnant zones are formed, which leads to overheating and acceleration of oxidative processes, which reduce the quality of the material.

A significant disadvantage of this method is the incomplete use of the temperature potential of the drying agent, which significantly reduces the technical and economic indicators.

Of the known solutions, the closest in technical essence and the achieved result to the invention is a method for drying grain and granular materials (see RF patent RU 2171958 C1, class F26В 3/14, 17/12). Drying is carried out by feeding the material from top to bottom, and the heat carrier penetrates the layer in the transverse direction. The spent heat carrier is removed. At the same time, the potential of the drying agent is not fully used. The degree of working out of the coolant in terms of temperature - no more than 10 ... 15%.

The objective of the present invention is to increase the degree of working out of the coolant in temperature to increase the productivity of the dryer. As a result of using this method, a more complete development of the coolant is achieved with a concomitant improvement in the economic indicators of the dryer.

The specified technical result is achieved by the fact that a part of the heat carrier spent in the drying zone is supplied to the grain preheating zone, where it contacts in the counterflow mode with the incoming cold granular material and heats it to a temperature close to the temperature of the drying agent. As a result, the grain enters the isothermal drying zone preheated to a temperature close to the temperature of the coolant, which has a positive effect on reducing the drying time and leads to an increase in the productivity of the apparatus as a whole.

Thus, to solve the problem posed, an energy-saving mine dryer for grain crops is proposed, containing a housing, mesh cylinders, a dense bulk layer of grain material, a coolant supply pipe, a sector feeder, a wet grain feed pipe and an exhaust coolant outlet, characterized in that for the purpose of energy saving for a more complete treatment of the coolant is equipped with an internal separating cylinder, a movable regulator cylinder and a movable ring.

Figure 1 shows a general view of the dryer.

The dryer contains a housing 1, an inner dividing cylinder 2, a movable regulator cylinder 3, mesh cylinders 4, a dense bulk layer of grain material 5, a coolant supply pipe 6, a sector feeder 7, a movable ring 8, a loading pipe 9 and an exhaust coolant outlet pipe 10.

It is known from the theory and practice of the processes of drying granular and granular materials (Kavetsky G.D. Equipment for the production of plastics. M .: Chemistry, 1986. - 224 p.; Rudobashta S.P., Kartashov E.M. Diffusion in chemical-technological processes.M .: KolosS, 2010. P.337-342; Rudobashta S.P., Dmitriev V.M., Planovskiy A.N. mechanical engineering, 1979. No. 4. P.14) that cereals belong to the group of moist materials with high diffusion resistance. They are characterized by a very long drying time (up to 10 ... 12 hours). An additional limitation that determines the duration of the process of mass transfer of moisture inside the weevil is the maximum permissible temperature of the drying process, which differs for fodder and seed stock. A common kinetic property of cereals is a fairly rapid removal of moisture in the initial period of drying. Then, as the internal moisture content decreases, the grain structure becomes denser, which leads to a significant decrease in the diffusion permeability coefficient and, as a consequence, to a significant final drying time. All of the above causes a long (several hours) real time for the drying process and the associated significant energy consumption.

The dryer works as follows. The dried grain moves under the action of gravity in an annular blown layer formed by two mesh cylinders 4 in the mode of a dense cross-blown layer. The speed of the wet material is set by the sector feeder 7. The speed of the coolant in the layer is 0.12 ... 0.2 m / s. At the same time, at the initial stage of drying (zone B in Fig. 1), approximately one third of the total amount of moisture in the dried grain material is quickly removed, the heat carrier is processed almost completely both in terms of moisture and temperature and is not of interest for further use for purposes energy saving (to be removed from the dryer through branch pipe 10). The height of zone B is assigned on the basis of knowledge of the kinetics of the drying process of a specific grain crop according to reference literature and is set using a movable cylinder-regulator 3. In zone C, the grain is heated almost to the temperature of the drying agent. The potential of the drying agent is used only to remove moisture from the weevil. However, due to the significant diffusion resistance to the process of internal mass transfer of moisture in the weevil, the drying time at the final stage is significant. At the same time, the coolant is not fully processed in terms of temperature, which worsens the economic performance of the dryer. Therefore, in order to more fully use the potential of the coolant, its part leaving the grain layer in zone C is directed to the heating zone A of the wet grain entering the dryer (Fig. 1 shows the direction of movement of the coolant from zone C with solid arrows). In zone A, the incoming wet grain is heated in a counterflow mode (the optimal speed of the coolant in the layer is 1.5 ... 2.0 m / s). The height of zone A depends on many factors: the size of the weevil, the type of crop, the initial temperature of the grain, the presence of surface moisture, etc. In practice, the height of zone A is set by measuring the outlet temperature of the heating medium. The height of zone A is increased by moving the movable ring 8 until the temperature of the outgoing heat carrier becomes comparable to the temperature of the grain material entering the drying process. Under this condition, the potential of the coolant is fully used. A further increase in the height of the heating zone is undesirable due to an increase in the hydraulic resistance of the dryer.

Compared to the prototype, with equal overall dimensions, the performance of the proposed dryer, depending on the dried culture, the initial moisture content of the product and other conditions, increases by 18 ... 26% due to:

- more complete use of the potential of the coolant;

- preheating the material to be dried with the used heat carrier.

The use of the proposed dryer provides the following advantages in comparison with existing designs:

- increase in the degree of working out of the coolant;

- the possibility of optimal choice of the height of the wet grain heating zone and the optimal choice of the height of the heat carrier take-off zone for returning to the heating zone;

- increase in productivity due to accelerated heating by the spent heat carrier of the wet material entering for drying;

- improvement of economic indicators due to a more complete use of the potential of the coolant.

- optimal organization of the drying process, taking into account the type of dried

grain material, its size, initial moisture content and mass transfer characteristics of caryopses.

Claims (1)

An energy-saving mine dryer for grain crops, containing a housing, mesh cylinders, a dense bulk layer of grain material, a heating medium supply pipe, a sector feeder, a wet grain feed pipe and an exhaust heat medium outlet, characterized in that it is equipped with an internal separating cylinder, movable regulating cylinder and movable ring.

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