RU2479808C1 - Seed and grain infrared drying method, and device for its implementation - Google Patents

Abstract

FIELD: heating.

SUBSTANCE: infrared drying method of materials, and mainly seeds and grain, consists in the fact that material is moved horizontally, influenced with a drying agent, IR-radiation, tempered and returned to drying chambers. A new feature of the proposed method is that material is moved with a directed drying agent flow that is recirculated; after tempering, the material is subject simultaneously to impact of IR-radiation and the drying agent; then, only to impact of the drying agent; material is separated and one of its parts is cooled, and the other one is tempered after having been mixed with wet material.

EFFECT: primary combined impact of IR-radiation on seeds after tempering allows increasing moisture removal, and recirculation of the drying agent allows reducing drying costs.

2 dwg

Description

The invention relates to the drying of seeds and grain and can be used in agriculture.

A known method of infrared drying of plant materials, according to which the material is loaded, moved on a grate, exposed to a drying agent and infrared radiation and unloaded (A. S. Ginzburg, V. A. Rezchikov. Drying food products in a fluidized bed. M .: "Food industry ”, 1966, p.124-126).

A device for its implementation, containing a fan, air heater, drying chamber, infrared lamps, a vibrating agent (A. Ginzburg, V. A. Rezchikov. Drying of food products in a fluidized bed. M .: "Food industry", 1966, p. 124-126).

This method and device are not widely used in agriculture due to the rapid heating of the material with a relatively slow moisture removal.

There are various methods and devices that slow down the heating rate and intensify moisture removal in the presence of infrared (IR) drying, for example, pulsed infrared drying / RU 2393397, BIPM No. 18 06/27/2010, analogue /, however, this drying method is characteristic of vegetable seeds, unconventional and rare plants and is not suitable for seeds and grains of cereal crops, the properties of which differ significantly from the properties of seeds of vegetable crops, and the drying means is an order of magnitude or more in productivity.

A known method of drying grain, which consists in the fact that the material is horizontally displaced, exposed to a drying agent, infrared radiation, traced and returned to the cycle.

A device for implementing this method is known, containing a conveyor belt, elevator, a source of infrared radiation, means for supplying a drying agent and return to the conveyor belt after bedding, grain tracking bin, screw conveyor / Penkin Alexander Alexandrovich. Development of an infrared radiation device for heat treatment of grain. Dissert. for a job. scientist step. Cand. tech. Sciences, 2005, p. 119-121 /.

These method and device in technical essence are closest to the claimed and taken as a prototype.

The disadvantage of this method is that after curing, when, as a result of moisture migration to the surface of the grains, intensive drying modes are allowed, which include infrared drying, the grain is initially treated with a drying agent, and then infrared drying is provided. In addition, the method is cyclic, i.e. It does not provide continuous operation, and the device is not energy-saving, since the spent drying agent is discharged into the environment.

An object of the invention is to increase the drying efficiency.

The stated technical problem is achieved in that the method of infrared drying, which consists in the fact that the material is horizontally moved, is affected by a drying agent, infrared radiation, is traced and returned to the drying chambers for drying, characterized in that the material is moved by a directed flow of the drying agent, which is recycled , after curing, the material is simultaneously exposed to infrared radiation and a drying agent, then only a drying agent is separated and one part is cooled, and the other, after mixing with wet material, is traced.

The stated technical problem is achieved in that the device for infrared drying of seeds and grains containing noria, a source of infrared radiation, means for supplying a drying agent and a tracking bin, according to the invention is equipped with a casing connected by an air duct to the means for supplying a drying agent with the possibility of its recirculation.

The invention is illustrated by drawings.

In FIG. 1 shows a process diagram of a device - continuous IR dryers; figure 2 is a model of this dryer, tested in the laboratory.

The scheme of the device includes a conveyor 1 of wet grain, loading elevator 2, case 3 of an aerogeloid type dryer, an air channel 4, a grill 5, IR drying chambers 6, convective drying 7, a casing 8, an IR radiation source 9, a threshold 10, a dispenser 11, discharge elevator 12, grain cooler 13, cooler fan 14, heat generator fan 15, heat generator 16, shark valve 17, coolant valve 18, tracking bin 19. In addition, the circuit includes the following elements: fluidized bed of grain 20, outdoor air 21 , wet grain 22, heated grain 23, recirculation incriminating grain 24, grain after billet 25, dry chilled grain 26.

The model model diagram includes a fan 27, a damper 28, an air heater 29, an air channel 30, a grill 31, an IR emitter 32, a reflector 33, a grain layer 34, a drying chamber 35, a threshold 36, a grain tank 37, a valve 38, 39, 40 41, an anemometer 42, a casing 43, a grain hopper 44, a recirculation duct 45, a bunker hopper 46, a thermometer 47, the Terem 4 measuring complex 48. The casing 43 is connected by an air duct 45 to the fan 27.

The operation of the device is as follows.

Pre-cleaned wet grain or seeds from the receiving compartment (temporary storage) by conveyor 1 is fed into noria 2 and into chambers 6 and 7, placed in the housing 3, then it is transferred to the outlet of the lattice 5 by a directed flow of the drying agent, pumped by the fan 15 into the air duct 4 The height of the layer 20 is controlled by a threshold 10, a portion of the grain is taken for cooling by the batcher 11 and sent to the ventilated hopper 13 by the noriya 12, the rest is dumped into the bucket of the elevator 2 and enters the bunker bunker 19. After baking, the grain in the mixture with wet enters to steps 6 and 7, etc. When the chamber 6 is overflowed, the excess grain by the valve 17 is discharged into the bucket of the elevator 2. When the overflow bin 19 is overfilled, the level sensor in its upper part is triggered and the supply of wet grain 22 stops, the flow of this grain also stops when the cooler 13 (ventilated bunker) is full or in case of exit from it of the unsaturated grain.

Monitoring the moisture content of the grain from the cooler 13 can be carried out both by direct measurement with a portable moisture meter and a flow moisture meter with automatic stop of the conveyor 1.

The drying agent (coolant) is prepared in the heat generator 16, the fan 15 is pumped into the air channel 4.

The spent drying agent is taken from the casing 8 and sent to the fan 15 for air recirculation, the excess of this drying agent is discharged by the valve 18 into the environment. An infrared source 9, for example, a rotary gas emitter, is placed in the chamber 6 at an adjustable height, grain temperature is controlled at the inlet of the dispenser 11, when the set temperature is exceeded, the height of the grain seed layer on the grate 5 decreases, and when the temperature is lowered, the height of this layer increases.

The method is as follows.

The material is horizontally moved along the grate by a drying agent, simultaneously exposed to infrared radiation and a convective drying agent, and then only by a drying agent, they are separated, one part is cooled, the other after being mixed with wet material is traced and returned to the drying chambers.

The main difference between IR drying and other types of thermal effects on the material is the rapid heating of the material. IR drying has found widespread use in the food industry for drying porous plant materials that have little resistance to moisture transfer. The grain has a colloidal structure and is characterized by high resistance to moisture transfer, therefore, when the maximum permissible temperature is reached, moisture removal is negligible.

However, during curing (for grain duration 2 ... 4 hours), moisture in the caryopsis is redistributed and the moisture field is leveled, while part of the moisture passes into the shell, which has a porous structure and easily gives moisture away. Therefore, when drying grain after baking with any intensity, not only does its temperature not increase, but it drops down to the temperature of a wet thermometer, which has been established by many researchers. But as soon as the moisture of the shell is evaporated, the temperature of the grain increases rapidly, therefore, it is necessary to reduce the temperature of the agent and the intensity of exposure to infrared radiation. In the proposed method, intense heating is implemented in a chamber in which infrared radiation and a convective drying agent are jointly affected by grain, and then the intensity of exposure is reduced (the infrared effect is stopped), at the exit from chamber 7, the grain is divided into two parts, one part is cooled, the other is recycled, mixed with wet and sent for baking, and it is cooled by an energy-saving method, i.e. when supplying external air in an amount of 200 ... 300 m ³ / h · t for 3 ... 5 hours in a ventilated hopper. During this time, with this supply, the temperature of the grain will decrease from 46 ... 43 ° C, and that of seeds from 43 ... 39 ° C to a temperature 4 ... 6 ° C higher than the outside air with a moisture removal of 1.7 to 3%.

When moving along a lattice with a directed exit of jets, a dense fluidized bed is formed, which avoids overheating of the part of the material closest to the emitter, but at the same time heats up the entire mass of grain passing through chamber 6.

During IR drying, not only the grain on the grate is heated, but also the enclosing structures of the IR emitter. Therefore, the drying agent leaving the chambers 6 and 7 has a high drying potential, which is advisable to use when it is recycled (from the casing 8 through the duct 45). According to experimental data, in the general case, heat saving for seeds due to recirculation reaches ~ 15%, for grain - 20%.

To determine the effectiveness of the proposed drying method and to clarify the moisture removal per passage, we studied the process of IR drying on a model.

The work of the model was carried out as follows.

The humidified material was loaded into the hopper 44, the threshold 36 and the valve 39 set the specified height of the layer 34, and the flow rate of the fan 27 - the performance of the material.

By adjusting the voltage on the heater 29, a predetermined temperature of the drying agent supplied under the grate 31 is set. The moving material on the grating 31 is simultaneously exposed to infrared radiation and a convective drying agent, then only by a convective drying agent and selected in a container 37, moisture removal is determined, and traced in a hopper 46 and return to hopper 44 for a new drying cycle. The spent drying agent duct 45 was returned to the fan 27 for recycling. Unlike the industrial design of an IR dryer, the model was characterized by cyclic operation (tracking and cooling were carried out in a ventilated container).

Example. Testing the method of IR-drying in a laboratory model on wheat seeds

The main parameters of the model: length 1 m, width of the transporting channel 0.1 m, threshold height - 0.06 m, live section of the sieves 5.9%, heater power 1.5 kW, infrared emitter power - 1 kW. Three modes of drying wheat with moisture W = 21% were investigated:

1 - IR drying + pulsed convective drying + cooling (analogue);

2 - baking + convective drying + IR drying + cooling (prototype);

3 - baking + combined drying (IR drying + convective) + convective drying + cooling (the claimed method).

Experimental conditions: The total duration of curing, drying and slow cooling of the seeds for 4 hours was adopted, of which we take to be in the heated state for ~ 3 hours, we determine the permissible temperature for heating the seeds and the drying agent. According to the formula of S.D. Ptitsyn

where τ is the duration of stay of seeds in a heated state, min.

/ S.D. Ptitsyn. Grain dryers. M .: Mashgiz, 1962, p. 52./

We obtain t _c = 44 ° C, and the temperature of the drying agent t ac we determine based on the fact that in the fluidized bed t _ac = t _c + 3 ... 5 ° C.

Let us take t _ac = 48 ° C, the speed of the drying agent was ~ 1 m / s, the seed consumption was ~ 30 kg / h, the duration of the curing cycle was 1.5 hours, the cooling time in the ventilated hopper was 2.5 hours, and the specific air supply for cooling 300 m ³ / h · t, the residence time of the seeds in the fluidized bed is ~ 7 min, the outdoor temperature is 20 ° C, the return to exhaust air recirculation is ~ 30%.

The main results of experiments on drying wheat seeds are given in the table.

Indicator Value Modes one 2 3 Moisture removal for the first cycle,% 1.8 2.0 2,4 Moisture removal for the second and next cycles,% ~ 1.6 ~ 1.7 ~ 2.0 Seed temperature after drying, ° C 42 43 42 Seed temperature after cooling, ° C 25.5 26.0 26.0 Additional moisture removal during cooling,% 1,5 1,6 1.7 Specific energy consumption MJ / kg isp. moisture 5.86 5,4 4.8 Increase in moisture removal,% - - 17 Reduction of energy consumption for drying,% - - 13

It has been established that the primary combined effect of IR radiation on seeds after bedding makes it possible to increase moisture removal by 17% compared with the primary exposure to convective drying agent, and the recirculation of the drying agent allows drying costs to be reduced by ~ 13%.

Claims (1)

The method of infrared drying of materials, mainly seeds and grains, which consists in the fact that the material is horizontally moved, exposed to a drying agent, IR radiation, traced, returned to the drying chamber, characterized in that the material is moved by a directed flow of the drying agent, which is recycled, after tracking the material is simultaneously exposed to IR radiation and a drying agent, then only a drying agent is separated and one part is cooled, and the other, after mixing with wet material, is traced.

Images