CN212158087U

CN212158087U - Grain drying system

Info

Publication number: CN212158087U
Application number: CN202020497004.6U
Authority: CN
Inventors: 李艳娇; 高亚民; 程世哲
Original assignee: Shenyang Hong Cheng Shiji Refrigeration Equipment Co ltd
Current assignee: Shenyang Hong Cheng Shiji Refrigeration Equipment Co ltd
Priority date: 2020-04-08
Filing date: 2020-04-08
Publication date: 2020-12-15
Anticipated expiration: 2030-04-08

Abstract

A grain drying system, a high-temperature evaporator, a primary cold water tank, a heat recovery heat exchanger and a primary cold water pump are cooling circulation loops. The outlet of the high-temperature evaporator is provided with a primary bypass pipeline to the spray dehumidification device, and a primary spray water collecting tank is pumped back to a primary cold water tank by a pump to form a primary spray circulation loop. The low-temperature evaporator, the secondary cold water tank, the dehumidification heat exchanger and the secondary cold water pump are a dehumidification circulation loop. The outlet of the low-temperature evaporator is provided with a secondary bypass pipeline to the spray dehumidification device, and a secondary spray water collecting tank is pumped back to a secondary cold water tank to form a secondary spray circulation loop. The low-temperature condenser, the first-stage hot water tank, the first-stage heating heat exchanger and the first-stage hot water pump are a first-stage heating circulation loop. The high-temperature condenser, the secondary hot water tank, the secondary heating heat exchanger and the secondary hot water pump are a secondary heating circulation loop. The grain drying high-temperature heat pump unit replaces a boiler, changes the original dehumidification mode, and then sends heat recovery and dehumidification heat exchangers after dust removal and preliminary dehumidification, and then heats up.

Description

Grain drying system

Technical Field

The utility model belongs to refrigeration and heating equipment, in particular to grain drying system is an energy-concerving and environment-protective device that can replace traditional boiler to satisfy grain stoving, owing to increased the raise dust phenomenon that spray dust collector has avoided traditional grain stoving in-process simultaneously.

Background

China is the largest food producing country and consuming country in the world, and the annual total production of food is about 5 hundred million tons. Due to climate reasons, the loss of mildew, germination and the like caused by the fact that the grains cannot be dried in the sun or fail to reach the safe moisture standard is up to 5 percent every year. If 5 hundred million tons of grains are produced per year, the loss is 2500 ten million tons. Drying is one of the most important links in the postpartum treatment of grains, and the principle condition for ensuring the grain storage safety is to reduce the grain moisture below the safe moisture through drying. Meanwhile, whether the drying operation is proper or not directly influences the grade, processing quality and eating quality of the grains, and further influences the economic benefits of grain farmers and grain circulation enterprises and the life quality of people.

However, from the national scale, there are still many outstanding contradictions in the drying of food in our country: the drying capacity of the grain remains insufficient overall: the quality of the dried grains is poor, especially the corn; high drying energy consumption, energy waste and the like.

The traditional grain drying process mainly adopts a drying mode combining a boiler and a drying tower, wherein a coal-fired boiler is mainly used due to the operation cost, but the application of the coal-fired boiler is more and more limited along with the deep implementation of the policy of energy conservation and environmental protection, and the relatively clean gas-fired boiler cannot replace the position of the coal-fired boiler in grain drying due to a plurality of factors such as higher operation cost, incapability of ensuring gas supply and the like.

And at this moment, heat pump drying technology is widelys promoting in a plurality of stoving fields, also try to adopt heat pump technology to dry in grain stoving field in many places, heat pump stoving adopts the open stoving mode of air source more at present, this kind of mode main objective is to replace traditional boiler, use outdoor air to send to the stoving indoor with the temperature that outdoor air heating heaies up to stoving product needs simultaneously as the heat pump heat source, the advantage of this kind of open air source heat pump relative traditional boiler is that it is clean energy, higher region in southern temperature also has certain energy-conserving effect, but it also has the limitation that can not neglect: firstly, in areas with lower environmental temperature, particularly in northern areas, the environmental temperature is mostly lower than 0 ℃ even more than twenty-below-zero ℃ in winter, the energy efficiency of the air source heat pump is very low at the moment, even the COP is lower than 2, at the moment, an electric compensation mode has to be adopted, the energy consumption is not different from that of an electric boiler, the energy consumption is huge, the production cost of products is invisibly provided, the burden of enterprises is increased, the competitiveness is reduced, and even the enterprises are closed.

No matter which drying method is adopted, the difference of the partial pressure of the water vapor between the surface of the drying material and the ambient air is increased, the open type drying system only adopts the temperature control to achieve the purpose that the partial pressure of the water vapor on the surface of the grain is greater than the partial pressure of the water vapor on the ambient air, the method only provides the air supply temperature for increasing the drying speed, but the method increases the drying speed, but easily causes the grain fragmentation and reduces the quality of the grain, and the closed type drying and dehumidifying system can achieve the purpose of increasing the difference of the partial pressure of the water vapor between the surface of the grain and the ambient air by controlling the temperature and controlling the humidity of the air to achieve the purpose of improving the drying speed. So most people have now all realized this problem and have adopted closed dehumidification drying system, but grain is dried still has another problem, and it is more serious that the raise dust phenomenon that causes is exactly that the husk of grain drops, can cause the polluted environment on the one hand, and on the other hand adopts the heat pump stoving in-process can block up the heat exchanger, causes heat exchange efficiency to descend, increases the stoving cost, leads to the unable fine popularization of heat pump stoving technique.

The closed drying system that this device adopted, adopt the mode that high temperature heat pump and drying tower combine promptly, nevertheless change original dehumidification mode, but utilize original air exit (dehumidification mouth) to send back exhaust humid air and spray dehumidification equipment, the dehumidification heat exchanger of heat pump drying system is sent into to the air after dust removal and preliminary dehumidification processing, detach moisture and retrieve heat wherein and heat up to the temperature that grain stoving needs again through the heat exchanger that heaies up, the aforesaid problem has been solved promptly, and the system adopts intelligent control to need not artifical on duty, the cost of labor has also been reduced.

SUMMERY OF THE UTILITY MODEL

The utility model aims at providing a grain drying system, in order to overcome shortcomings such as current technology energy consumption height, polluted environment, poor quality, labour cost height

The technical scheme is as follows:

a grain drying system comprises a grain drying high-temperature heat pump unit.

The technical key points are as follows:

the high-temperature evaporator, the first-stage cold water tank, the heat recovery heat exchanger and the first-stage cold water circulating pump of the grain drying high-temperature heat pump unit are connected through pipelines to form a cooling circulation loop.

The pipeline from the outlet of the high-temperature evaporator to the primary cold water tank is provided with a primary bypass pipeline to a primary spray pipe of a primary spray component of the spray dehumidification device, a primary spray pipeline bypass valve is arranged on the primary bypass pipeline, and a primary spray water collecting tank is connected with a pipeline and is sent back to the primary cold water tank through a primary spray water circulating pump to form a primary spray circulation loop.

The low-temperature evaporator, the secondary cold water tank, the dehumidification heat exchanger and the secondary cold water circulating pump of the grain drying high-temperature heat pump unit are connected through pipelines to form a dehumidification circulating loop.

The pipeline from the outlet of the low-temperature stage evaporator to the second-stage cold water tank is provided with a second-stage bypass pipeline to a second-stage spray pipe of a second-stage spray component of the spray dehumidification device, a second-stage spray pipeline bypass valve is configured on the second-stage bypass pipeline, and the second-stage spray water collecting tank is connected with a pipeline and is sent back to the second-stage cold water tank through a second-stage spray water circulating pump to form a second-stage spray circulation loop.

The low-temperature-stage condenser, the first-stage hot water tank, the first-stage heating heat exchanger and the first-stage hot water circulating pump of the grain drying high-temperature heat pump unit are connected through pipelines to form a first-stage heating circulating loop.

The high-temperature condenser, the second-stage hot water tank, the second-stage heating heat exchanger and the second-stage hot water circulating pump of the grain drying high-temperature heat pump unit are connected through pipelines to form a second-stage heating circulating loop.

And a centrifugal fan is arranged at the outlet of the secondary heating heat exchanger.

The heat recovery heat exchanger, the dehumidification heat exchanger, the first-stage heating heat exchanger and the second-stage heating heat exchanger are sequentially arranged.

The outlet of the spraying and dehumidifying device is connected with the heat recovery heat exchanger through a corresponding air duct to form a circulating loop of the dehumidifying and drying system.

The spraying and dehumidifying device comprises a primary spraying component and a secondary spraying component which are arranged in a spraying and dehumidifying device shell.

The first-level spraying assembly comprises a first-level spraying assembly shell, a first-level spraying pipe is arranged above the first-level spraying assembly shell, and a first-level spraying water collecting tank is arranged below the first-level spraying assembly shell.

The second-stage spraying component comprises a second-stage spraying component shell, a second-stage spraying pipe is arranged above the second-stage spraying component shell, and a second-stage spraying water collecting tank is arranged below the second-stage spraying pipe.

A second-stage spray water collecting tank filtering device is arranged above the first-stage spray water collecting tank, and a first-stage spray water collecting tank filtering device is arranged above the second-stage spray water collecting tank.

The inlet of the spraying and dehumidifying device is provided with an air outlet temperature sensor.

An inlet of the spraying and dehumidifying device is provided with an air distributing plate.

The outlet of the spraying and dehumidifying device is provided with a water baffle.

The outlet of the centrifugal fan is provided with an air supply outlet temperature sensor.

The primary cold water tank is provided with a primary cold water tank temperature sensor, the secondary cold water tank is provided with a secondary cold water tank temperature sensor, the primary hot water tank is provided with a primary hot water tank temperature sensor, and the secondary hot water tank is provided with a secondary hot water tank temperature sensor.

By adopting the device, the grain drying high-temperature heat pump unit is utilized to replace the original boiler, and the original dehumidification mode is changed: the original air outlet is used for sending back the exhausted wet air to the spraying and dehumidifying equipment, the air subjected to dust removal and preliminary dehumidification is sent to the heat recovery heat exchanger and the dehumidifying heat exchanger of the heat pump drying system, the heat in the air is removed, the moisture is removed, the heat in the air is recovered, the temperature is raised to the temperature required by grain drying through the temperature raising heat exchanger, the system is intelligently controlled without manual watching, and the labor cost is also reduced.

The advantages are that:

1. the system is simple to install, convenient to operate and wide in applicability.

2. The system has stable operation and accurate control, and can ensure the operation efficiency of different regions and different seasons.

3. Unattended operation: the operation of the grain drying high-temperature heat pump unit and the frequency of the centrifugal fan frequency converter are controlled according to the temperature of the air supply opening and the air exhaust opening of the drying tower, the system has perfect temperature setting and protection measures, manual guard is not needed, and the operation is safe and stable

4. The quality is good, and the phenomena of grain fragmentation and waist explosion are reduced.

5. The system has low noise and does not influence the normal work of other equipment during operation.

6. The operation cost is low, the heat in the drying tower is recovered, an additional heat source is not needed, and the operation energy efficiency is not lower than 3.0.

7. Clean environmental protection, equipment itself adopts clean energy, adopts spray dehydrating unit to avoid the raise dust phenomenon that grain stoving process caused simultaneously.

Drawings

Fig. 1 is a schematic diagram of the system of the present invention.

Fig. 2 is a partially enlarged view of the spray dehumidifier, four water tanks and the grain drying high-temperature heat pump unit shown in fig. 1.

Fig. 3 is an internal cross-sectional view of the primary spray assembly of the present invention.

Figure 4 is an internal cross-sectional view of the second stage spray assembly of the present invention.

A grain drying high-temperature heat pump unit 1, a spray dehumidifier 2, a heat recovery heat exchanger 3, a dehumidification heat exchanger 4, a first-stage heating heat exchanger 5, a second-stage heating heat exchanger 6, a centrifugal fan 7, a drying tower 8, a second-stage hot water tank 9, a first-stage hot water tank 10, a second-stage cold water tank 11, a first-stage cold water tank 12, a first-stage cold water circulating pump 13, a second-stage cold water circulating pump 14, a first-stage hot water circulating pump 15, a second-stage hot water circulating pump 16, a second-stage spray water circulating pump 17, a first-stage spray water circulating pump 18, a second-stage spray pipeline bypass valve 19, a first-stage spray pipeline bypass valve 20, a low-temperature stage compressor 21, a high-temperature stage compressor 22, a low-temperature stage condenser 23, a high-temperature stage condenser 24, a low-temperature stage evaporator 25, a high-temperature, The primary spray assembly 32, the primary spray header tank 33, the secondary spray assembly 34, the manhole 35, the secondary spray header tank 36, the water baffle 37, the air duct 38, the air supply outlet temperature sensor 39, the air outlet temperature sensor 40, the secondary hot water tank temperature sensor 41, the primary hot water tank temperature sensor 42, the secondary cold water tank temperature sensor 43, the primary cold water tank temperature sensor 44, the secondary spray header tank filter 45, the primary spray header tank filter 46, the primary spray pipe 47, the secondary spray pipe 48, and the spray dehumidifier housing 49.

Detailed Description

A grain drying system comprises a grain drying high-temperature heat pump unit 1 (the known technology), and the temperature can reach more than 90 ℃.

The high-temperature evaporator 26, the primary cold water tank 12, the heat recovery heat exchanger 3 and the primary cold water circulating pump 13 of the grain drying high-temperature heat pump unit 1 are connected through pipelines to form a cooling circulation loop.

The primary cold water circulating pump 13 is positioned between the primary cold water tank 12 and the heat recovery heat exchanger 3, and the inlet of the primary cold water circulating pump 13 is connected with the primary cold water tank 12.

A pipeline from the outlet of the high-temperature stage evaporator 26 to the primary cold water tank 12 is additionally provided with a primary bypass pipeline to a primary spray pipe 47 of the primary spray assembly 32, a primary spray pipeline bypass valve 20 is arranged on the primary bypass pipeline to adjust the spray amount, spray condensate water is collected to a primary spray water collecting tank 33, and the pipeline connection is returned to the primary cold water tank 12 through a primary spray water circulating pump 18 to form a primary spray circulating loop.

The inlet of the primary spray water circulating pump 18 is connected with a primary spray water collecting tank 33.

The low-temperature evaporator 25, the secondary cold water tank 11, the dehumidifying heat exchanger 4 and the secondary cold water circulating pump 14 of the grain drying high-temperature heat pump unit 1 are connected through pipelines to form a dehumidifying circulation loop.

A pipeline from the outlet of the low-temperature stage evaporator 25 to the secondary cold water tank 11 is additionally provided with a secondary bypass pipeline to a secondary spray pipe 48 of the secondary spray assembly 34, a secondary spray pipeline bypass valve 19 is arranged on the secondary bypass pipeline to adjust the spray amount, secondary spray condensate water is collected to a secondary spray water collecting tank 36, and the pipeline connection is returned to the secondary cold water tank 11 through a secondary spray water circulating pump 17 to form a secondary spray circulating loop.

The inlet of the second stage spray water circulating pump 17 is connected with a second stage spray water collecting tank 36.

The low-temperature-stage condenser 23, the first-stage hot water tank 10, the first-stage warming heat exchanger 5 and the first-stage hot water circulating pump 15 of the grain drying high-temperature heat pump unit 1 are connected through pipelines to form a first-stage heating circulation loop.

The first-stage hot water circulating pump 15 is positioned between the first-stage hot water tank 10 and the first-stage heating heat exchanger 5, and the inlet of the first-stage hot water circulating pump 15 is connected with the first-stage hot water tank 10.

The high-temperature-stage condenser 24, the second-stage hot water tank 9, the second-stage warming heat exchanger 6 and the second-stage hot water circulating pump 16 of the grain drying high-temperature heat pump unit 1 are connected through pipelines to form a second-stage heating circulating loop.

The second-stage hot water circulating pump 16 is positioned between the second-stage hot water tank 9 and the second-stage heating heat exchanger 6, and the inlet of the second-stage hot water circulating pump 16 is connected with the second-stage hot water tank 9.

The outlet of the secondary heating heat exchanger 6 is provided with a centrifugal fan 7.

The heat recovery heat exchanger 3, the dehumidification heat exchanger 4, the first-stage warming heat exchanger 5 and the second-stage warming heat exchanger 6 are sequentially arranged.

The spray dehumidifier 2 includes a primary spray assembly 32 and a secondary spray assembly 34 disposed within a spray dehumidifier housing 49.

The first-level spray assembly 32 comprises a first-level spray assembly shell, a first-level spray pipe 47 is arranged at the inner upper part, and a first-level spray water collecting tank 33 is arranged at the lower part.

The secondary spray assembly 34 includes a secondary spray assembly housing with a secondary spray pipe 48 disposed above and a secondary spray header 36 disposed below. The secondary spray pipe 48 exits below the dew point temperature and is initially dehumidified within the secondary spray assembly 34.

A second-level spray water collecting tank filtering device 45 (a known product) is arranged above the first-level spray water collecting tank 33, a first-level spray water collecting tank filtering device 46 (a known product) is arranged above the second-level spray water collecting tank 36, and residues such as grain husks in the air from the grain drying tower 8 are isolated outside the two filtering devices after being sprayed and removed, so that the residues do not enter a water system to block a heat exchanger, and can be cleaned regularly.

Further, an inlet of the first-stage spraying assembly shell (spraying and dehumidifying device 2) is provided with an air distribution plate 31.

The outlet of the second-level spray assembly shell (the spray dehumidifying device 2) is provided with a water baffle 37.

The air with the dust such as husk discharged from the drying tower 8 is ensured to enter the corresponding air duct 38 after entering the spraying and dehumidifying device 2 and being subjected to dust removal and dehumidifying treatment uniformly, so that the heat exchanger is prevented from being blocked by the dust such as husk, and the sprayed water is prevented from being carried into the air duct 38.

The heat recovery heat exchanger 3, the dehumidification heat exchanger 4, the first-level temperature rise heat exchanger 5, the second-level temperature rise heat exchanger 6, the centrifugal fan 7 and the drying tower 8 are connected through corresponding air ducts 38 between the air supply outlet, the drying tower 8 air outlet and the spraying dehumidification device 2 inlet are connected through the air ducts 38, the spraying dehumidification device 2 outlet and the heat recovery heat exchanger 3 are connected through the corresponding air ducts 38, and the connection forms a dehumidification drying system circulation loop.

Further, the centrifugal fan 7 adjusts the wind speed frequency thereof by a supply-air outlet temperature sensor 39 (T1) disposed at the supply-air outlet of the drying tower 8 and a discharge-air outlet temperature sensor 40 (T2) disposed at the discharge-air outlet of the drying tower 8.

Further, the primary cold water tank 12 is provided with a primary cold water tank temperature sensor 44 (T6), the secondary cold water tank 11 is provided with a secondary cold water tank temperature sensor 43 (T5), the primary hot water tank 10 is provided with a primary hot water tank temperature sensor 42 (T4), and the secondary hot water tank 9 is provided with a secondary hot water tank temperature sensor 41 (T3).

The grain drying high-temperature heat pump unit 1 controls the unloading and the starting and stopping of the unit according to corresponding hot water temperature sensors (a first-stage hot water tank temperature sensor 42 and a second-stage hot water tank temperature sensor 41), meanwhile, the cold water temperature is protected from freezing, and whether the unit needs to be shut down with anti-freezing protection is judged according to temperature values detected by the cold water temperature sensors (a first-stage cold water tank temperature sensor 44 and a second-stage cold water tank temperature sensor 43). The system is ensured to operate safely and reliably.

The two stages of spraying components in the spraying and dehumidifying device 2 are respectively provided with a corresponding manhole 35 for maintenance personnel to pass through.

The grain drying high-temperature heat pump unit 1 comprises a low-temperature stage compressor unit: a low-temperature stage compressor 21, a low-temperature stage condenser 23, a low-temperature stage evaporator 25, and a low-temperature stage gassing accumulator 27.

The discharge port of the low temperature stage compressor 21 is connected to the refrigerant inlet of the low temperature stage condenser 23.

The refrigerant outlet of the low-temperature stage condenser 23 is connected with one refrigerant inlet of the low-temperature stage gas-separating accumulator 27.

The suction port of the low-temperature stage compressor 21 is connected to one refrigerant outlet of the low-temperature stage air-separating accumulator 27.

The refrigerant inlet of the low-temperature stage evaporator 25 is connected with the other refrigerant outlet of the low-temperature stage gas-separating liquid storage device 27, and a low-temperature stage expansion valve 29 is arranged on a pipeline between the low-temperature stage evaporator and the low-temperature stage gas-separating liquid storage device.

The refrigerant outlet of the low-temperature stage evaporator 25 is connected with the other refrigerant inlet of the low-temperature stage gas-separating accumulator 27.

The exhaust of the low-temperature stage compressor 21 is provided with a corresponding pressure sensor.

The grain drying high-temperature heat pump unit 1 comprises a high-temperature-stage compressor unit: a high temperature stage compressor 22, a high temperature stage condenser 24, a high temperature stage evaporator 26, and a high temperature stage vapor knock-out drum 28.

The discharge of the high temperature stage compressor 22 is connected to the refrigerant inlet of the high temperature stage condenser 24.

The refrigerant outlet of the high-temperature-stage condenser 24 is connected with one refrigerant inlet of the high-temperature-stage gas-separation accumulator 28.

The suction port of the high-temperature stage compressor 22 is connected to a refrigerant outlet of the high-temperature stage air-separation accumulator 28.

The refrigerant inlet of the high-temperature stage evaporator 26 is connected with the other refrigerant outlet of the high-temperature stage gas-separation liquid accumulator 28, and a high-temperature stage expansion valve 30 is arranged on a pipeline between the high-temperature stage evaporator and the high-temperature stage gas-separation liquid accumulator.

The refrigerant outlet of the high-temperature stage evaporator 26 is connected with the other refrigerant inlet of the high-temperature stage gas-separating accumulator 28.

The exhaust of the high temperature stage compressor 22 is provided with a corresponding pressure sensor.

And each pipeline is provided with a respective maintenance valve.

Claims

1. The utility model provides a grain drying system has grain stoving high temperature heat pump set (1), its characterized in that:

a high-temperature-stage evaporator (26), a primary cold water tank (12), a heat recovery heat exchanger (3) and a primary cold water circulating pump (13) of the grain drying high-temperature heat pump unit (1) are connected through pipelines to form a cooling circulation loop;

a pipeline from the outlet of the high-temperature stage evaporator (26) to the primary cold water tank (12) is provided with a primary bypass pipeline to a primary spray pipe (47) of a primary spray assembly (32) of the spray dehumidification device (2), the primary bypass pipeline is provided with a primary spray pipeline bypass valve (20), and a primary spray water collecting tank (33) is connected with a pipeline and is sent back to the primary cold water tank (12) through a primary spray water circulating pump (18) to form a primary spray circulating loop;

a low-temperature-stage evaporator (25), a secondary cold water tank (11), a dehumidifying heat exchanger (4) and a secondary cold water circulating pump (14) of the grain drying high-temperature heat pump unit (1) are connected through pipelines to form a dehumidifying circulating loop;

a pipeline from the outlet of the low-temperature stage evaporator (25) to the secondary cold water tank (11) is provided with a secondary bypass pipeline to a secondary spray pipe (48) of a secondary spray component (34) of the spray dehumidification device (2), a secondary spray pipeline bypass valve (19) is arranged on the secondary bypass pipeline, and a secondary spray water collecting tank (36) is connected with a pipeline and is sent back to the secondary cold water tank (11) through a secondary spray water circulating pump (17) to form a secondary spray circulating loop;

a low-temperature-stage condenser (23), a first-stage hot water tank (10), a first-stage heating heat exchanger (5) and a first-stage hot water circulating pump (15) of the grain drying high-temperature heat pump unit (1) are connected through pipelines to form a first-stage heating circulating loop;

a high-temperature-stage condenser (24), a secondary hot water tank (9), a secondary temperature-raising heat exchanger (6) and a secondary hot water circulating pump (16) of the grain drying high-temperature heat pump unit (1) are connected through pipelines to form a secondary heating circulating loop;

a centrifugal fan (7) is arranged at the outlet of the secondary heating heat exchanger (6);

the heat recovery heat exchanger (3), the dehumidification heat exchanger (4), the primary heating heat exchanger (5) and the secondary heating heat exchanger (6) are arranged in sequence;

the outlet of the spraying and dehumidifying device (2) is connected with the heat recovery heat exchanger (3) through a corresponding air duct (38) to form a circulating loop of the dehumidifying and drying system.

2. The grain drying system of claim 1, wherein:

the spraying and dehumidifying device (2) comprises a primary spraying assembly (32) and a secondary spraying assembly (34) which are arranged in a spraying and dehumidifying device shell (49);

the primary spray assembly (32) comprises a primary spray assembly shell, a primary spray pipe (47) is arranged above the inner part of the primary spray assembly shell, and a primary spray water collecting tank (33) is arranged below the primary spray pipe;

the secondary spray assembly (34) comprises a secondary spray assembly shell, a secondary spray pipe (48) is arranged above the inner part of the secondary spray assembly shell, and a secondary spray water collecting tank (36) is arranged below the inner part of the secondary spray assembly shell;

a second-level spray water collecting tank filtering device (45) is arranged above the first-level spray water collecting tank (33), and a first-level spray water collecting tank filtering device (46) is arranged above the second-level spray water collecting tank (36).

3. The grain drying system of claim 2, wherein:

an air outlet temperature sensor (40) is arranged at the inlet of the spraying and dehumidifying device (2).

4. The grain drying system of claim 2, wherein:

an inlet of the spraying and dehumidifying device (2) is provided with an air distributing plate (31);

the outlet of the spraying and dehumidifying device (2) is provided with a water baffle (37).

5. The grain drying system of claim 1, wherein:

an outlet of the centrifugal fan (7) is provided with an air supply outlet temperature sensor (39).

6. The grain drying system of claim 1, wherein:

the primary cold water tank (12) is provided with a primary cold water tank temperature sensor (44), the secondary cold water tank (11) is provided with a secondary cold water tank temperature sensor (43), the primary hot water tank (10) is provided with a primary hot water tank temperature sensor (42), and the secondary hot water tank (9) is provided with a secondary hot water tank temperature sensor (41).