RU2119137C1 - Loose material (grain) drying method - Google Patents

Abstract

FIELD: agriculture; drying of grain and seeds. SUBSTANCE: proposed method of drying includes preliminary heating of loose material to maximum tolerable temperature by fresh heat carrier, preliminary drying, final drying and cooling. Mixture of fresh heat carrier and heat carrier used in preliminary heating and cooling is used for preliminary and final drying of loose material. difference in temperatures of heat carrier mixtures delivered for preliminary drying and final drying of loose material is set by one control shutter installed on ring manifold with preservation of constant volumetric delivery of each mixture. Delivery of fresh heat carrier for preliminary heating of loose material is regulated or cut off by shutters installed on pipeline delivering fresh heat carrier into ring manifold and before preliminary heating of loose material. Delivery of fresh heat carrier obtained by taking in outside air and heating it in heat generator to required temperature is provided by fan installed before heat generator. EFFECT: carrying out drying at maximum temperatures, possibility of using the method in dryers of different types. 3 cl, 1 dwg

Description

 The invention relates to a technique for drying bulk materials, mainly grain and seeds of agricultural crops, and can be used in agriculture, chemical, food and other industries.

 A known method of drying grain and oilseeds by heating a mixture of source and recycle material, draining, drying during transverse blowing with a spent drying agent, drying and cooling in a shaft type apparatus, while draining is carried out for 3-5 minutes, and drying - 2-4 minutes after which additional curing is carried out for 5-10 minutes and drying is carried out at a descending temperature regime of the drying agent, moreover, part of the drying agent and cooling air spent in the mine-type apparatus is bypassed and dried e is conducted to mixing with fresh drying agent and fire purification (see. the description of the invention to the author's certificate USSR N 732639, IPC F 26 B 3/06, 17/12, publication 05.05.80).

 A disadvantage of the known method of drying grain is that it involves the use of large-sized sedimentary chambers in the direction of the part of the spent drying agent and the furnace. The disadvantages also include lack of efficiency, caused by heat loss with the spent drying agent in the heater.

 A known method of drying grain, which consists in supplying a coolant to freely falling grain, pre-heating the grain without evaporating moisture from it, then the grain is washed with a coolant of an equilibrium state with it, then the grain is dried with a damp drying agent, then the grain is again washed with a coolant of equilibrium with state and dry the grain with an un-moistened drying agent to a predetermined humidity (see the description of the invention to the USSR copyright certificate N 714111, IPC F 26 B 3/02, publication 25.02.80).

 The disadvantage of this known method of drying grain is the lack of efficiency caused by heat loss from the spent coolant on cooling.

 There is a known method of drying grain, including mixing the source and recirculating grain flows, preheating to the maximum permissible temperature, purging with waste heat carrier, baking, final drying, cooling and unloading, while after mixing the source and recirculating grain, the flow is divided into two parts, each part is subjected baking, one part is dried in the mine of the recirculation cycle, the other part is subjected to preheating and subsequent purging with the spent coolant, for the parts are mixed and re-separated, one of the parts being mixed with the source grain, and the drain is separated from the other and fed to the part that has been previously subjected to curing and drying in the recirculation shaft, and the remaining curing is finally dried and cooled. after draining the part, the process of drying the grain in the mine of the recirculation cycle is carried out with a mixture of fresh and spent on drying and cooling coolants, and pre-heating the mixture of the source and recirculating The cores and final drying are carried out with fresh coolant (see description of the invention to the USSR author's certificate N 1730517, IPC F 26 B 3/06, 17/12, publication 04/30/92).

 The disadvantages of the known method of drying grain are its complexity and lack of efficiency caused by heat loss with the spent heat carrier when heating the grain, as well as the inevitable decrease in drying efficiency when regulating or completely stopping the supply of fresh coolant for preheating when drying volatile or brittle bulk materials.

 There is a known method of drying grain, in which all the material that has undergone preliminary heating and curing is fed into the isothermal drying zone, and upon leaving the zone it is divided into two streams, one of which is sent for recycling, and the other for cooling. Wet material is fed into the heater, where it is heated by the heat carrier leaving the heat generator. As the heater, any device can be used that provides intensive heating of the material without deterioration, for example, a fluidized bed apparatus. The heated wet material from the preheater is sent to the mixer, where it is mixed with dry recycle material coming from the drying chamber and having the same temperature as the wet material. After mixing, the mixture is sent to a thermally insulated container, where it is aged and the contact heat and moisture exchange process takes place. After curing, the material enters the drying chamber, where it is dried by the heat carrier in isothermal mode, coming from the heat generator. The spent heat carrier may be mixed with this coolant, but not all, and partially to provide the required evaporation of moisture. Similarly, the heat transfer agent used in the heater can be disposed of. The material dried in the chamber, when leaving it, is divided into two streams, one of which is sent to the mixer (for recirculation), and the other to the cooler, where the material is purged with atmospheric air. The dried and chilled material is continuously discharged from the cooler. If necessary, the air heated during cooling of the material can be directed to mixing with fresh heat carrier supplied for drying from the heat generator [1].

 The disadvantage of the prototype is its lack of efficiency, because the spent heat carriers when heating the grain and cooling it are served only at the stage of final drying, as well as the inability to carry out the drying process at the highest possible temperatures at the beginning and at the end of drying.

 The problem to which this invention is directed, is to increase the efficiency of the method of drying bulk materials, mainly grain, by increasing the efficiency while conducting the drying process from the maximum allowable temperatures for each bulk material at each stage of drying, the versatility of the method for various types of drying installations.

 The essence of the invention lies in the fact that in the method of drying bulk materials, mainly grain, comprising preheating the bulk material to the maximum permissible temperature with fresh coolant, drying, final drying and cooling, drying, as well as the final drying of the bulk material is carried out with a mixture of fresh and spent on preheating and cooling of coolants.

 The temperature difference of the coolant mixtures supplied for drying and final drying of the bulk material is set by one control valve located on the annular collector, keeping the volumetric flow rate of each mixture unchanged.

 The supply of fresh coolant for the preheating of bulk material is regulated or completely stopped by the valves located on the fresh coolant supply pipe to the annular manifold and before the preheating of the bulk material.

 The fresh coolant obtained by taking in the outside air and heating it in the heat generator to a predetermined temperature is supplied by a fan installed in front of the heat generator.

 This ensures an increase in the efficiency of the drying process compared to the prototype due to the use of thermal energy of the spent heat carrier for preheating and cooling, while the drying process is carried out at the maximum allowable temperatures of the bulk material at each drying stage, the advantages of recirculation and direct-flow dryers are combined in one installation.

 The proposed method of drying bulk material, mainly grain, is illustrated by the drawing, which shows a functional diagram of a method of drying bulk material, mainly grain, in accordance with this invention.

In the drawing, the following notation:
1 - preheating of bulk material;
2 - drying of bulk material;
3 - the final drying of the bulk material;
4 - cooling of bulk material (cooler);
5 - fan;
6 - heat generator;
7 - shutter;
8 - shutter;
9 - pipeline supplying fresh coolant in the annular collector 10;
10 - ring collector;
11 - shutter;
12 - pipeline supplying a mixture of coolants from the annular collector 10 for drying 2;
13 - pipeline supplying a mixture of coolants from the annular collector 10 for final drying 3;
14 - coolant entering the annular collector 10 and consisting of a mixture of fresh and spent on pre-heating 1 coolant;
15 - coolant entering the annular collector 10 from the cooler 4;
16 - raw bulk material in a recirculation drying mode;
17 - raw bulk material with direct-flow drying;
18 - recirculation of dry bulk material;
19 - dry bulk material.

 The proposed method of drying bulk material, mainly grain, are as follows.

 Bulk material in the recirculation drying mode (the main mode as the most economical) moves in the following order: preheating 1; drying 2; final drying 3; cooling 4. After cooling, 4 part of the dry bulk material is returned to preheating 1, the rest is removed from the drying process.

 Bulk material in direct-flow drying mode moves in the following order: drying 2; final drying 3; cooling 4.

 Preparation of fresh coolant is carried out by taking the outside air by the fan 5 and heating it in the heat generator 6 to a predetermined temperature. The supply of fresh coolant for preheating 1 bulk material is regulated or completely stopped by shutters 7 and 8 located on the pipeline 9 and before preheating 1 bulk material. At the beginning of the drying process, when working with the next bulk material, the shutters 7 and 8 are fully opened. When the fresh coolant is insufficiently supplied to the preheater 1, the shutter 7 is covered, and if it is excessive, the shutter 8 is covered.

 If the bulk material does not allow drying using preheating 1, then, completely closing the shutter 8, the drying unit from the recirculation drying mode is transferred to direct-flow mode. In this case, the bulk material is fed to the drying unit directly for drying 2. Cooling 4 of the bulk material is carried out with outside air. Outside air with the help of a fan (not shown in the diagram, installed before or after cooler 4) passes cooler 4 and is supplied to the annular manifold 10. The coolant fresh and spent on preheating 1 and cooling 4 enter the annular collector 10, forming a mixture. Using the damper 11, the mixture enters the pipelines 12 and 13 with different temperatures. The temperature difference of the coolants in the pipelines 12 and 13 is up to thirty or more degrees. Reducing the flow of cooler coolant 15 to the pipe 13 by the shutter 11, thereby increasing the flow of hotter heat carrier 14 to the pipe 13. In this case, the remaining parts of the heat carrier, that is, the majority of the heat carrier 15 and the smaller part of the heat carrier 14, will enter the pipe 12. Outgoing from this, the temperature of the mixture of coolants in the pipeline 12 will be lower than the temperature of the mixture of coolants in the pipe 13. The different temperatures of the coolants entering the drying 2 and the final drying 3 are necessary for I-drying process to the maximum permissible temperature of the bulk material at each drying stage. The damper 11 due to the annular collector 10 does not change the volumetric flow in each of the pipelines 12 and 13, but only affects the redistribution of the flow of coolant 14 and 15 inside the annular collector 10.

 The method of drying bulk material, mainly grain, according to this invention allows to increase the efficiency of the drying process, to carry out drying at the maximum allowable temperatures of the bulk material at each stage of drying, to provide a temperature difference of the heat carriers supplied to each stage of drying, with one damper, to regulate the flow of heat carrier to preheating of bulk material (which allows heating for each bulk material at optimal conditions, without reducing the drying efficiency s), dryer transfer from the recirculation mode to the continuous-flow drying mode without preheating particulate material. Installing a fan that delivers fresh coolant to the drying process in front of the heat generator allows you to improve the layout of the drying unit and remove the temperature effect of the hot coolant in the case of installing the fan after the heat generator, as well as to remove the effect of the clogged coolant in the case of installing the fan after preheating.

Claims (3)

 1. The method of drying bulk material, predominantly grain, comprising preheating the bulk material to the maximum permissible temperature with fresh coolant, drying, final drying and cooling, the final drying being carried out with a mixture of fresh and spent on pre-heating and cooling coolants, characterized in that the drying is carried out also a mixture of fresh and spent on pre-heating and cooling coolants, and the temperature difference of the mixtures of coolants A fed to the final drying and final drying bulk material, establish one regulating flap situated on an annular manifold, maintaining unchanged the volumetric flow of each mixture.  2. The method according to claim 1, characterized in that the supply of fresh coolant for preheating bulk material is controlled or completely stopped by shutters located on the fresh coolant supply pipe to the annular manifold and before preheating the bulk material.  3. The method according to claim 1, characterized in that the supply of fresh coolant obtained by taking outside air and heating it in a heat generator to a predetermined temperature, carries out a fan installed in front of the heat generator.