SU1730517A1 - Method of drying grain by recycling - Google Patents

Abstract

This invention relates to the recycling drying of bulk materials and can be used in agriculture for drying grain. The purpose of the invention is to increase the intensity of drying and the energy efficiency of the process. The method involves mixing the initial and recirculating grain flows, preheating to the maximum permissible temperature, purging with the spent coolant, spitting, final drying, cooling and unloading, and after mixing, the flow is divided into two parts, each is bent, one part is dried in the recycle cycle shaft, the other is preheated and then purged with spent heat carrier, then the parts are mixed and re-separated, with one of the parts is fed for mixing with the original grain, and the other is separated from the drain and fed to that part, which is preliminarily subjected to retrieving and drying in the mine of the recirculation cycle, and the remaining remaining after draining is subjected to extracting, final drying and cooling, and the process of drying the grain into the mine is kept with a mixture of fresh and spent coolant drying and cooling, and the preheating of the mixture of initial and recirculating grain and the final drying are conducted with fresh coolant. 1 il. (Ls

Description

The invention relates to the technology of recycling drying of bulk thermolabile materials, mainly grain and oilseeds, and can be used in agriculture and in grain-receiving enterprises of the agro-industrial complex.

Methods are known for recirculating drying of loose thermolabile materials, mainly grains and oilseeds.

The closest to the present invention is a method of drying grain and oilseeds n.

where the initial grain is mixed with the one dried in the recirculation cycle, including the preheater and the coolant recovery zone; the mixture is preheated to the maximum allowable temperature and at the same time dried, pre-extracting the heated grain, and then dried with spent coolant during cross-blowing; additional extracting is carried out in the tophole bins, after which one part of the grain is dried to standard moisture in the upper and

 with about

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The lower zones of the mine grain dryer are cooled and discharged from it, and the other part, the recirculating part, is returned to the beginning of the process for mixing with the initial grain before the preheating. The heat carrier spent in the lower drying zone and when the grain is cooled is mixed in the furnace with fresh and reused in the preheater and in the mines of the grain dryer, and the waste in the upper zone is directed to the drying of the preheated grain during transverse blowing in the disposal zone.

The disadvantages of the prototype are the underestimation of the intensity and energy efficiency of the drying process, which is explained by the absence of the separation stage after mixing the initial and recirculated grain before preheating and direct drying of the grain in the mines, i.e. lack of recycling cycles. Due to the absence of binning, there is no redistribution of heat and moisture between the seedlings of the initial and recirculating grains, therefore, the evaporation surface in the mixture and the moisture transfer coefficients in the original grain are underestimated, which reduces the drying rate and moisture saturation of the coolant. In the absence of recirculation in mines, the speed of movement of the grain and, accordingly, the intensity of mixing are low, which necessitates the use of a low-temperature heat transfer fluid, at which the drying rate is lowered and the specific consumption of heat and electricity is overestimated.

The aim of the invention is to increase the intensity of drying and the energy efficiency of the process.

The goal is achieved by mixing the source and recirculating grains, the flow is divided into two parts and subjected to separate preliminary bleaching, after which one part is dried in the shaft of the recirculation cycle, and the second part is subjected to preheating and subsequent purging with spent heat carrier. these parts are mixed and re-divided, one part being fed for mixing with the initial grain, and the other is separated out and drained to the part that the preliminary is subjected Bleeding and drying in the mine of the recirculation cycle, and the remaining part after draining is subjected to bleeding, final drying, cooling and directing to unloading.

The drawing shows a functional diagram of the proposed method of drying.

In the drawing, the following notation is accepted: 1 - mixing of the initial and recirculating grain flows; 2 - dividing the mixture into two parts, directed to separate preliminary casting, after which the first part - to drying in the recirculation cycle, and the second - to preheating; 3

- mixing of the first part of the grain flow after stage 2 with the grain flow separated by the drain before final drying; 4 - preliminary extraction of the mixture of grain formed in step 3; 5 - drying of the grain after stage 4 in the mine of the recirculation cycle with a mixture of fresh and spent heat carriers; 6 - preliminary extraction of the second part of the grain, directed after separation in stage 2, to preheating; 7 - preheating the grain to the maximum allowable temperature with fresh coolant; 8 - blowing of the preheated grain with the heat-transfer agent; 9 - mixing the grain streams after drying in steps 5 and 8;

10- re-separation into two streams of the mixture of grain formed in step 9, directed: the first to the beginning of the process to mix with the original grain in step 1, and the second to the final drying;

11- discharge by the discharge from the second stream of the part of the grain that is sent for mixing with the first stream selected in step 2;

12- extracting the part of the grain to be finally dried; 13- final drying of the grain with fresh coolant to a predetermined humidity; 14

-cool grain outside air; 15

- unloading of grain from the dryer and submission to storage; 16 - preparation of the heat carrier in the furnace or in the heater; 17 - mixing of coolants fresh and spent at the stages of drying and cooling of the grain.

The source grain sent for drying is mixed in step 1 with the previously dried recirculating flow, after mixing the grain flow in step 2 is divided into two parts, one of which in step 3 is mixed with the flow of recirculated grain selected by the drain from the final drying, and the mixture is pretreated in step 4, then dried in step 5 in the mine of the recirculation cycle with a mixture of fresh and used coolants.

The second part of the grain flow selected in step 2 is predled in step 6, in step 7 preheated to the maximum allowable temperature with fresh coolant, and then dried in the utilization column in step 8 with coolant exhausted during all subsequent stages of drying and cooling the grain. After drying in steps 5 and 8, the grain streams are mixed in step 9 and re-divided in step 10 into two streams. The first recirculating part is fed to the beginning of the process for mixing with the initial grain, and the second part is sent for final drying, and from this part an excess grain is separated out at stage 11, which is transferred to the mixing at stage 3 before pre-spraying and drying in the mine. cycle.

Grain flow at a flow rate corresponding to a given standard moisture content is subjected to binning at stage 12, final drying at stage 13 with fresh coolant and cooling at stage 14 with outside air, after which at stage 15 it is discharged from the grain dryer.

Fresh coolant to the preheater and for final drying comes from the furnace 16 or heater, and the grain worked at the stages of drying and cooling is mixed with fresh in the mixer 17, and then fed to drying 5 in a recirculation cycle.

Example. Drying is carried out in a mining grain dryer with a capacity of 50 t / h with transport equipment with a capacity of 100 t / h with a recovery column capacity of 3 m. The capacity of the mines of the recirculation cycle and the final drying of 20 tons each. In the dryer, there are 2 servings per 100 t / h each - one for lifting the grain to the separation in step 2. and the second for lifting the grain to the separation in step 11.

The grain of seed wheat with the initial parameters is supplied for drying: humidity L / I 24.5% and temperature & 15 ° С (equal to the temperature of atmospheric air di tae) at the flow rate of Cu 32.3 t / h (conversion factor according to the drying instructions is 1.55). Specified final moisture content of the grain WK 14%. The initial grain is mixed in step 1 with a recirculating flow Gp, the flow rate of which is 67.7 tonnes per hour. The decrease in grain moisture at the stages of drying and cooling will be 3% (Wp 17%), and the heating temperature of the grain mixture, which is equal to the maximum allowable, is 40 ° C. The parameters of the grain flow mixture are as follows: GCM 3

100 t / h; WCM 19.7% and 6U 32 ° C. As is known, the lowest specific energy consumption for drying will be at the highest temperatures and relative humidity in the spent heat carrier, i.e. in our case at tom 40 - 43 ° С, mouth 70 - 80%. From the equations for varying the temperature and humidity of the grain, such conditions are provided with a duration of grain blowing, preheated to 40 ° C, for 2, 3 minutes. Starting from the capacity of the utilization column, the consumption of grain directed to preheating.

will be 58.7 t / h.

During preheating at stage 7 and disposing of the spent coolant, the drying process proceeds at a high speed, since as a result of

stage 6, the moisture was distributed on the surface of all the grains, the temperature of the initial grain increased from 15 to 32 ° С. therefore, the coefficient of internal and external moisture transfer has significantly increased.

These conditions ensure a high drying rate and an economical use of heat and electricity.

The second part of the grain after separation in stage 2 with a flow rate of 41.3 t / h goes to

mixing in stage 3 with recirculated, separated by a discharge at a rate of 67.7 t / h (the consumption of evaporated moisture is not taken into account). Thus, the grain flow at a rate of 41.3 + 67.7 109 t / h is fed to the bin in step 4 and to the subsequent drying in the recirculation cycle in step 5. This flow takes place in mines at high speed with good mixing, which allows the process to evaporate.

mostly surface moisture, i.e. at high intensity of drying and economical use of energy. The decrease in grain moisture in both streams (after separation in step 2) is 2.7%.

The duration of the grain drying at the stage is 5-11 minutes, the drying rate Np is 0.25% / min; when drying at step 8 - Nn 1.17% / min.

At stage 11, a part of the total flow of the grain mixture is separated with a flow rate of 32.3 t / h, which is fed to the bin at stage 12 and the subsequent drying from 17 to 14% with fresh coolant, cooling

outside air in stage 14 and unloading. The rest of the grain is discharged at stage 11 by discharge and returned to mixing at stage 3.

Claims (1)

In the final drying mine, the residence time of the grain is 36 minutes, the average drying rate is MD 0.083% / min. Claims The method of recirculating the drying of grain, including mixing the initial and recirculating grain flows, preheating to the maximum allowable temperature, purging with the spent coolant, extracting, final drying, cooling and unloading, characterized in that, in order to increase the intensity of drying and energy efficiency After mixing the initial and recirculating grain, the flow is divided into two parts, each part is subjected to bleaching. one part is dried in the recycle cycle shaft, the other part is preheated and followed by purging with the spent heat carrier, then the parts are mixed and re-separated, with one of the parts being fed for mixing with the original grain, and the drain is separated from the other and fed to the part that is previously subjected to binning and drying in the mine of the recirculation cycle, while remaining, after the discharge, part is drained, leaving the final drying and cooling, the mixture is dried in the mine of the recycling cycle fresh and spent on drying and cooling coolants, and Preheating of the mixture of the initial and recirculating grains and the final drying are carried out with fresh coolant. 6i, Uu, 8ts 00. Wp.Bj,