A constant temperature grain soaking device and method

Abstract

This invention discloses a constant-temperature grain soaking device and method, belonging to the field of baijiu brewing technology. To solve the problem of uneven grain water absorption caused by the coupling of time difference in feeding and temperature stratification in large-capacity grain soaking tanks, this invention adopts a grain-first, water-later process, ensuring all grains simultaneously come into contact with the soaking water; compressed air is used to purge and level the grain layer; a top annular water inlet ensures uniform initial water temperature; an independent circulating water tank collects and heats the soaking water from the top of the tank, then evenly distributes and re-injects water from the bottom circumferentially, allowing hot water to penetrate the grain layer from bottom to top. This invention, through the synergistic effect of "grain-first, water-later" and "bottom circulating heating," eliminates the coupling effects of time difference and temperature stratification, significantly improving the consistency of soaking moisture, saving water and energy, and is suitable for large-capacity, large-scale baijiu brewing production.

Description

Technical Field

[0001] This invention relates to the field of liquor brewing technology, specifically to a constant temperature soaking device and method for large-capacity grain soaking tanks. Background Technology

[0002] Soaking the grains is a crucial step in the baijiu brewing process, and the quality of soaking (grain water absorption rate and moisture uniformity) directly affects the efficiency of subsequent fermentation and the quality of the final product. The soaking water temperature is the core factor determining the rate of water absorption and the uniformity of moisture distribution in the grains.

[0003] Currently, the brewing industry mostly uses small-capacity grain soaking tanks for production because of their small size, thin grain layer, and relatively easy control of water temperature. However, for large-capacity grain soaking tanks (height-to-diameter ratio usually ≥1.5, grain layer height ≥2m), due to the large volume of water and the thickness of the grain layer, the grain soaking process faces two coupled physical challenges: First, the time difference problem. In the traditional "water first, grain later" process, the hot water added first has already begun to dissipate heat while waiting for the grain to be added. The soaking time of the grain added first is longer than that of the grain added later. The grain in different positions has an inconsistent water absorption start time, resulting in irreversible differences in water absorption rate. Second, the spatial thermal stratification problem. When the tank with a large height-to-diameter ratio is in a static state, a stable vertical temperature stratification will form. The water temperature at the bottom is high and the water temperature at the top is low. Natural convection is difficult to overcome the thermal boundary layer resistance, and the temperature difference between the upper and lower layers inside the tank can reach tens of degrees Celsius. What's even more challenging is that the two problems reinforce each other: the grains that are put into the tank first tend to accumulate in the high-temperature zone at the bottom due to gravity settling, resulting in longer soaking time and higher water temperature, leading to excessive water absorption; the grains that are put into the tank later are suspended in the low-temperature zone at the top, resulting in insufficient water absorption. The combined effect of these two factors results in a water absorption rate difference that is far greater than that of a single factor, and it is irreversible within the limited soaking period.

[0004] Some existing technologies have attempted to achieve liquid circulation heating in grain soaking tanks through external circulation pipelines (such as CN212270057U). This solution improves temperature uniformity to some extent, but still has the following shortcomings: (1) The circulation pipeline is usually drawn out from the side wall of the grain soaking tank, and the return water also returns from the side wall. It is impossible to form an orderly heat convection in the vertical direction, and there is still a temperature gradient of cold at the top and hot at the bottom inside the tank. (2) The impact of the order of feeding on the uniformity of water absorption was not considered, and the problem of inconsistent initial soaking time caused by watering before grain was not solved; (3) Heating and circulation are coupled in the same loop, limiting the independence and stability of temperature control.

[0005] Therefore, in the context of large-capacity grain soaking tanks, existing technologies have not yet effectively solved the fundamental problem of increased water absorption rate differences caused by the superposition and coupling of time difference and thermal stratification. Summary of the Invention

[0006] In view of this, the present invention proposes a constant temperature grain soaking device and method, which aims to solve the problem of uneven water absorption of grain caused by time difference and thermal stratification coupling in large-capacity grain soaking tanks.

[0007] The technical solution of this invention is implemented as follows: This invention provides a constant-temperature grain soaking method, comprising the following steps: placing the grain to be soaked into a soaking tank; using compressed air to purge the surface of the grain layer inside the soaking tank to make the surface of the grain layer basically flat; after the grain is placed and purged, injecting soaking water into the soaking tank so that all the grains simultaneously come into contact with the water; after the soaking water has submerged the grains, drawing the soaking water from the top of the soaking tank to an external circulating water tank, and heating it to the target soaking water temperature in the circulating water tank; uniformly re-injecting the heated soaking water from the bottom of the soaking tank circumferentially into the tank, so that the hot water passes through the grain layer from bottom to top; continuously drawing out the water throughout the entire soaking cycle. heating The cycle of refilling continues until the soaking process ends.

[0008] This scheme ensures that all grains come into contact with hot water simultaneously through a "grain-first, water-later" approach, eliminating time differences caused by the order of feeding. Then, by evenly distributing water around the bottom circumference, the heated hot water flows upwards through the grain layer, using forced convection to break down natural vertical heat stratification and ensure uniform heat transfer along the tank's height. These two core steps work together: the grain-first, water-later approach provides uniform starting conditions for bottom-circulating heating, while bottom-circulating heating compensates for the temperature drop that might occur when hot water passes through the upper grain layer due to heat absorption. This synergistic effect matches the temperature compensation of the bottom grains with the initial water absorption of the top grains, achieving uniformity simultaneously in both time and space.

[0009] In some embodiments, a constant-temperature grain soaking device for implementing the above method is provided, comprising: a grain soaking tank; a feeding device disposed at the top of the grain soaking tank for feeding grain into the grain soaking tank; a compressed air purging device disposed at the top of the grain soaking tank for purging and leveling the surface of the grain layer after feeding and before water is introduced; a top water inlet device for injecting soaking water into the grain soaking tank after feeding; a circulating water tank, the inlet of which is connected to the upper part of the grain soaking tank through a first pipeline for receiving soaking water from the upper part of the grain soaking tank; a heating unit disposed in the circulating water tank or connected to the circulating pipeline of the circulating water tank for heating the soaking water to a target temperature; and a bottom water distribution device disposed at the bottom of the grain soaking tank and connected to the outlet of the circulating water tank, wherein the bottom water distribution device has multiple water outlets distributed circumferentially along the bottom of the grain soaking tank for re-injecting the heated soaking water into the tank in a circumferentially uniform manner.

[0010] This device separates the heating function of the soaking water from the soaking tank to an independent circulating water tank, allowing the heating process to take place fully within the tank and avoiding potential localized overheating or damage to the grain layer caused by direct heating within the soaking tank. The circumferentially uniform water distribution design of the bottom water distribution device ensures that the hot water is evenly distributed across the cross-section of the tank, forming a near-piston flow thermal propulsion mode, maximizing heat transfer efficiency in the vertical direction.

[0011] In some embodiments, the bottom water distribution device is a ring-shaped pipe arranged circumferentially along the bottom of the grain soaking tank, with multiple water outlets on the ring-shaped pipe. The ring-shaped pipe structure is simple and reliable, and easy to modify and install on the bottom of existing grain soaking tanks.

[0012] In some embodiments, the top water inlet device is an annular water inlet pipe located at the top of the grain soaking tank, with water outlet holes opened around the tank wall. The top annular water inlet design allows the initially injected soaking water to flow out evenly around the tank wall, avoiding damage to the grain surface or sudden temperature changes caused by hot water directly impacting the local grain layer in the traditional single-point water inlet method.

[0013] In some embodiments, the compressed air purging device has a purging angle of 15° to 45° with the horizontal plane, and a purging air pressure of 0.3 to 0.6 MPa. This parameter range can effectively disperse the protrusions on the top of the grain pile, while avoiding excessive air pressure that could cause the grain to splash or break.

[0014] In some embodiments, the constant temperature grain soaking device further includes a temperature detection unit and a control unit. The temperature detection unit is at least located at the bottom and top of the grain soaking tank. The control unit controls the working state of the heating unit and the circulation pump according to the feedback signal from the temperature detection unit, so that the return water temperature of the circulating water tank is maintained within a preset target range.

[0015] The present invention has the following advantages over the prior art: This invention, through its core collaborative design of "grain first, water later" and "bottom circumferential circulating heating," simultaneously eliminates the time difference caused by the order of feeding and the thermal stratification caused by vertical temperature differences in large-capacity grain soaking tanks. This results in more uniform water absorption by the grain in all areas of the tank, with significantly better moisture consistency than traditional processes and existing circulating heating schemes. By setting up an independent circulating water tank, the heating of soaking water and the maintenance of temperature inside the soaking tank are decoupled, ensuring stable and reliable system operation. The combination of compressed air purging and annular water inlet reduces ineffective soaking space and water consumption, saving water resources. Overall, this invention systematically solves the problem of controlling the uniformity of water temperature in large-capacity grain soaking tanks, providing a reliable technical guarantee for large-scale brewing production. Attached Figure Description

[0016] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0017] Figure 1 This is a schematic diagram of the constant temperature grain soaking device of the present invention.

[0018] In the diagram: 1-Grain soaking tank; 2-Feeding device; 3-Top water inlet device; 4-Circulating water tank; 5-Heating unit; 6-Bottom water distribution device; 7-Annular pipe; 8-Compressed air purging device; 9-Annular water inlet pipe; 10-Internal self-circulation system; 11-Self-circulation pump; 12-Self-circulation pipeline; 13-Temperature detection unit; 14-Control unit Detailed Implementation The technical solutions of the present invention will be clearly and completely described below with reference to the embodiments of the present invention. Obviously, the described embodiments are only a part of the embodiments of the present invention, and not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative effort are within the scope of protection of the present invention.

[0019] Example 1 like Figure 1 As shown, this embodiment provides a constant temperature grain soaking device, including a grain soaking tank 1, a feeding device 2, a top water inlet device 3, a circulating water tank 4, a heating unit 5, a bottom water distribution device 6, a compressed air purging device 8, a temperature detection unit 13, and a control unit 14.

[0020] The grain soaking tank 1 is a cylindrical stainless steel tank with a total height of 6m, an inner diameter of 4m, a height-to-diameter ratio of 1.5, and an effective volume of approximately 75m³. 3 This system is suitable for large-scale grain soaking operations with a single batch feed volume of approximately 20 tons. The top of the grain soaking tank 1 is equipped with an openable, sealed lid, and the bottom has a conical or flat-bottom structure to facilitate drainage and bottom water distribution. The tank wall of the grain soaking tank 1 is equipped with an insulation layer to reduce heat loss during the grain soaking process.

[0021] The feeding device 2 is located at the top of the grain soaking tank 1 and can be a conventional grain conveying equipment such as a screw conveyor, bucket elevator, or belt conveyor. The discharge port of the feeding device 2 is sealed to the inlet of the grain soaking tank 1 to prevent dust from overflowing during the feeding process. In this embodiment, the feeding device 2 uses a frequency-controlled screw conveyor, which can adjust the feeding speed as needed to avoid excessive accumulation of grain in local areas inside the tank.

[0022] A compressed air purging device 8 is located below the top cover of the grain soaking tank 1 and includes multiple purging nozzles evenly arranged along the circumference of the tank. The compressed air purging device 8 is connected to an external air compressor via a compressed air pipeline equipped with a solenoid valve and a pressure regulating valve. The outlet of the purging nozzles faces the surface of the grain layer inside the tank 1, with a purging angle of 15° to 45° to the horizontal plane, and a purging air pressure of 0.3 to 0.6 MPa. After feeding but before adding water, the compressed air purging device 8 is activated, sweeping the surface of the grain layer circumferentially to flatten any conical accumulation or localized undulations caused by feeding, significantly reducing the height difference of the grain layer. The purging time is 30 to 60 seconds. Compressed air purging is a non-contact leveling method, which avoids the grain damage that may occur when using wooden shovels or iron spades to level the grain surface manually. At the same time, it provides a uniform grain surface foundation for subsequent annular water intake. The flat grain layer allows the water flow from the top to be evenly distributed on the grain surface, avoiding the formation of "preferred flow" channels due to local grain surface depressions. These channels would cause hot water to seep down rapidly from local areas, causing short circuits in the flow field and reducing heat exchange efficiency.

[0023] The top water inlet device 3 is a ring-shaped water inlet pipe 9 located on the inner side of the upper part of the grain soaking tank 1. This ring-shaped water inlet pipe 9 is arranged circumferentially along the inner wall of the grain soaking tank 1, approximately 1 meter from the top of the tank. The diameter of the ring-shaped water inlet pipe 9 is DN80, and 36 water outlet holes are evenly distributed along the circumference of the pipe. The diameter of each water outlet hole is 10mm, and the opening direction of the water outlet holes is downward or obliquely downward to ensure that the water flows evenly in an umbrella-like pattern. The ring-shaped water inlet pipe 9 is connected to an external hot water supply system (such as a hot water tank or boiler) through a main water inlet pipe, which is equipped with an inlet valve and a flow meter. After the compressed air purging device 8 completes the leveling process, the inlet valve is opened, and soaking water is injected into the grain soaking tank 1 through the ring-shaped water inlet pipe 9. The temperature of the soaking water can be set from 65℃ to 85℃ depending on the type of grain. The design of the annular water inlet pipe 9 allows hot water to flow out evenly around the tank wall, avoiding damage to the grain surface or sudden temperature changes caused by the direct impact of hot water on the local grain layer in the traditional single-point water inlet method, thus achieving a gentle and uniform distribution of water during the first addition.

[0024] In this embodiment, the grain soaking process adopts a "grain first, water later" technique. First, all the grain to be soaked is added to the soaking tank 1 via the feeding device 2. The grain naturally accumulates inside the tank, and then the surface of the grain layer is smoothed by a compressed air blowing device 8. Finally, soaking water is injected through the top water inlet device 3. This feeding sequence ensures that all grains begin contact with hot water at the same time, eliminating the problem of inconsistent soaking start times caused by batches of grain being added to the tank in the traditional "water first, grain later" process. This eliminates the adverse effects of time differences on the uniformity of water absorption by the grains.

[0025] The upper side wall of the grain soaking tank 1 is provided with a water outlet, which is connected to the water inlet of the circulating water tank 4 through a first pipeline. The circulating water tank 4 is an independently installed stainless steel insulated tank with a volume of approximately 20% to 30% of the effective volume of the grain soaking tank 1. In this embodiment, the volume of the circulating water tank 4 is 20m³. 3 The first pipeline is equipped with a circulation pump and a filter. The circulation pump draws the soaking water from the upper part of the soaking tank 1 to the circulating water tank 4. The filter removes any grain debris and impurities that may be carried in the soaking water to prevent clogging of the subsequent water distribution holes. The circulating water tank 4 is equipped with a heating unit 5, which can be a steam coil heater or an electric heater, to heat the soaking water in the circulating water tank 4 to the target temperature required by the process. In this embodiment, the heating unit 5 uses a steam coil heater, and temperature regulation is achieved by controlling the opening of the steam valve. The circulating water tank 4 is also equipped with a stirring device to ensure uniform water temperature and avoid localized overheating.

[0026] The outlet of the circulating water tank 4 is connected to the bottom water distribution device 6 via a second pipeline. A return water pump and a flow regulating valve are installed on the second pipeline. The bottom water distribution device 6 is located at the bottom of the grain soaking tank 1, and its structure is similar to the top annular inlet pipe 9, being an annular pipe 7. The annular pipe 7 is arranged circumferentially along the bottom of the grain soaking tank 1, with a diameter of DN100. 24 water outlets, each 15mm in diameter, are evenly distributed along the circumference of the pipe. The outlets face upwards or at an angle upwards to allow hot water to spray upwards. The annular pipe 7 is fixed to the inner wall of the bottom of the grain soaking tank 1 by a bracket or directly buried in the tank foundation. During circulation, the return water pump pumps the heated soaking water from the circulating water tank 4 to the bottom water distribution device 6. The soaking water is injected into the grain soaking tank 1 in a circumferentially uniform manner through the water outlets on the annular pipe 7, allowing hot water to pass through the grain layer from bottom to top. Because the water outlets are evenly distributed circumferentially, the hot water is evenly distributed across the entire cross-section of the grain soaking tank 1, avoiding uneven flow caused by local water concentration.

[0027] During the soaking process, the circulation pump and return water pump are started to continuously execute the cycle of "water extraction from the top of the soaking tank 1 → heating in the circulation tank 4 → return injection through the bottom water distribution device 6". The circulation flow rate is set to 1 to 2 times the effective volume of the soaking tank 1 per hour; in this embodiment, the circulation flow rate is 80 m³ / h. 3 / h. During the circulation process, the temperature of the soaking water in the grain soaking tank 1 is replenished and maintained in a timely manner. Simultaneously, the upward flow of hot water utilizes the physical principle of thermal convection: water with lower density (higher temperature) naturally rises, while water with higher density (lower temperature) naturally flows downwards. This creates a thermal convection driving force consistent with the forced circulation direction, allowing heat to be quickly and evenly transferred to the entire grain layer. Particularly noteworthy is that in the "grain first, water later" process, the injected hot water experiences a temperature drop as it flows through the upper grain layer due to heat absorption by the grain. The circulating heated water injected at the bottom precisely compensates for this temperature loss, ensuring that both the upper and lower grains in the tank absorb water under optimized temperature conditions, achieving dual homogenization in both time and space dimensions.

[0028] The temperature detection unit 13 includes multiple temperature sensors, which are at least located at the bottom and top of the grain soaking tank 1. In this embodiment, four temperature sensors are evenly arranged along the height of the grain soaking tank 1 (e.g., at the bottom, 1 / 3 of the height, 2 / 3 of the height, and the top) to collect real-time data on the soaking water temperature at each point. Each temperature sensor is electrically connected to the control unit 14 and feeds back temperature signals to the control unit 14. The control unit 14 can be a PLC controller, a microcontroller, or an industrial computer. Based on the feedback signals from the temperature detection unit 13, it controls the operating status of the heating unit 5 (steam valve opening or electric heating power), the circulation pump, and the return water pump to maintain the return water temperature of the circulating water tank 4 within a preset target range (e.g., 75℃ ± 1℃). The control unit 14 can also automatically adjust the circulation flow rate and heating power according to the temperature differences at various measuring points within the grain soaking tank 1 to achieve dynamic optimization of the temperature distribution inside the tank.

[0029] This embodiment also provides a constant temperature grain soaking method using the above-mentioned constant temperature grain soaking device, which specifically includes the following steps: Step S1: Put the grain to be soaked into the grain soaking tank 1 through the feeding device 2. Control the feeding speed during the feeding process so that the grain will naturally accumulate in the tank.

[0030] Step S2: After feeding is completed, start the compressed air purging device 8 to sweep the surface of the grain layer in a circumferential direction. The purging air pressure is 0.3 to 0.6 MPa, and the purging time is 30 to 60 seconds, so that the surface of the grain layer is basically flat. After purging is completed, turn off the compressed air purging device 8.

[0031] Step S3: Open the water inlet valve of the top water inlet device 3, and inject soaking water into the grain soaking tank 1 through the annular water inlet pipe 9. The amount of water injected should be enough to completely submerge the grain (usually the water-to-grain mass ratio is 1.5:1 to 2.5:1). During the injection process, hot water flows out evenly along the outlet of the annular water inlet pipe 9 and sprinkles down the tank wall to the surface of the grain layer, avoiding direct impact of water flow on local grain layers.

[0032] Step S4: After the soaking water has completely submerged the grain, start the circulation pump to draw the soaking water from the top of the soaking tank 1 into the circulating water tank 4. At the same time, start the heating unit 5 to heat the soaking water in the circulating water tank 4 to the target soaking water temperature (e.g., 75°C).

[0033] Step S5: Start the return water pump to re-inject the heated soaking water in the circulating water tank 4 into the soaking tank 1 through the annular pipe 7 of the bottom water distribution device 6 and the water outlet on the annular pipe 7 in a circumferentially uniform manner, allowing the hot water to pass through the grain layer from bottom to top. Control the return water flow rate to 50 to 100 m³ / h. 3 / h, so that the outflow velocity is controlled between 0.2 and 0.4 m / s to avoid excessive impact on the grain layer.

[0034] Step S6: Throughout the soaking cycle (typically 8 to 16 hours), repeat steps S4 to S5. During this period, the temperature detection unit 13 monitors the temperature at various points within the soaking tank 1 in real time. The control unit 14 automatically adjusts the power of the heating unit 5 and the operating status of the circulation pump based on the temperature feedback signal, ensuring that the return water temperature of the circulating water tank 4 remains within the target range. After soaking is complete, stop the circulation, open the drain valve to drain the soaking water, and discharge the soaked grain through the outlet.

[0035] It is worth noting that the "grain first, water later" process and the "bottom circumferential circulation heating" described in this embodiment form a significant technical synergy. On the one hand, "grain first, water later" ensures that all grains begin soaking simultaneously, eliminating the time difference caused by the order of feeding in traditional processes, and providing a uniform starting condition for the subsequent circulation heating process. On the other hand, the bottom-up heat compensation achieved by bottom circumferential circulation heating effectively compensates for the inherent defect of the "grain first, water later" process where the water temperature drops after the hot water absorbs heat in the upper grain layer. These two core features are interdependent and work together, enabling the grains in all areas of the grain soaking tank 1 to complete soaking in an almost identical temperature environment, even under the high-diameter ratio conditions of a large-capacity grain soaking tank, achieving simultaneous homogenization in both time and space dimensions.

[0036] Example 2 The main difference between this embodiment and Embodiment 1 is that this embodiment provides a simplified constant temperature grain soaking device and method for the application scenario of modifying existing grain soaking tanks, which is particularly suitable for low-cost upgrading and modification of traditional grain soaking tanks that have already been put into use.

[0037] In this embodiment, the grain soaking tank 1 is an existing grain soaking tank already in use, and its height-to-diameter ratio also meets the condition of ≥1.5. During the modification process, the structure of the grain soaking tank 1 is not significantly altered. Instead, eight evenly distributed holes are opened at its bottom as the outlets of the bottom water distribution device 6, and the original bottom drainage pipe is modified to enable it to simultaneously perform water inlet and drainage functions. An external circulating water tank 4, a heating unit 5, a circulating pump, and a return water pump are added, and the water outlet on the upper side wall of the grain soaking tank 1 is connected to the circulating water tank 4 through a pipeline. The top water inlet device 3 can be simply modified from the original water inlet pipe by adding a water distribution ring or annular water distributor to the outlet end of the original water inlet pipe to enable circumferential water distribution. The compressed air purging device 8 can be equipped with several purging nozzles on the top of the grain soaking tank 1 as needed and connected to the compressed air pipeline in the factory area.

[0038] The soaking method is the same as in Example 1, and will not be repeated here. The simplified device described above was used to modify and test two existing soaking tanks in a winery. The results showed that before the modification, the moisture content range was approximately 9.7% to 11.2%, and the standard deviation was approximately 3.5% to 4.0%; after the modification, the moisture content range decreased to 2.1% to 2.8%, the standard deviation decreased to 0.8% to 1.1%, water consumption decreased by approximately 15% to 18%, and energy savings were approximately 20% to 22%.

[0039] Example 3 The main difference between this embodiment and Embodiment 1 lies in the specific structure of the bottom water distribution device 6. The bottom water distribution device 6 in Embodiment 1 adopted a ring pipe 7 structure, while this embodiment adopts a radial water distribution structure.

[0040] Specifically, the bottom water distribution device 6 includes a central water collection pipe and multiple radial water distribution pipes (e.g., 8, 12, or 16, depending on the tank diameter) extending outward from the central water collection pipe. The central water collection pipe is located at the center of the bottom of the grain soaking tank 1 and is connected to the main return water pipe. One end of each radial water distribution pipe is connected to the central water collection pipe, and the other end extends towards the tank wall of the grain soaking tank 1, with multiple water outlet holes on the pipe wall. The number, length, and density of the radial water distribution pipes and water outlet holes can be optimized according to the tank diameter to achieve uniform water distribution across the entire cross-section of the tank bottom.

[0041] The method for soaking grains in this embodiment is the same as in Embodiment 1, and will not be repeated here.

[0042] Example 4 The difference between this embodiment and Embodiment 1 lies in the timing coordination of the top water inlet device 3 and the compressed air purging device 8.

[0043] In this embodiment, the purging action of the compressed air purging device 8 and the water inlet action of the top water inlet device 3 are not completely separate. Instead, the water inlet is activated simultaneously in the later stages of purging, forming a transitional phase of "purging while water inlet". Specifically, after the compressed air purging device 8 is started, it first purifies separately for 20 to 30 seconds to make most of the grain layer surface flat. Then, while maintaining purging, water is introduced at a low flow rate (approximately 30% to 50% of the normal water inlet flow rate) for about 1 to 2 minutes. This allows the water flow to be further diffused by the compressed air flow during its descent, forming a water atomization effect and further reducing the impact of the water flow on the grain layer. Afterward, purging is stopped, and the water inlet flow rate is adjusted to the normal value.

[0044] Example 5 The difference between this embodiment and Embodiment 1 lies in the control logic of the control unit 14.

[0045] In this embodiment, the control unit 14 employs a conventional PID control algorithm. Based on the temperature signals from the bottom and top of the grain soaking tank 1 fed back by the temperature detection unit 13, it adjusts the heating power of the heating unit 5 and the rotation speed of the circulating pump to maintain the return water temperature of the circulating water tank 4 within a preset target range (e.g., 75℃±1℃). The control unit 14 can also use a larger circulation flow rate in the early stage of grain soaking to quickly establish thermal convection, and appropriately reduce the circulation flow rate in the later stage of grain soaking to save energy.

[0046] Example 6 The difference between this embodiment and Embodiment 1 lies in the materials and insulation structure of the grain soaking tank 1 and the circulating water tank 4.

[0047] In this embodiment, the grain soaking tank 1 is made of 304 or 316L stainless steel, with a polished inner wall to reduce grain adhesion. The tank is covered with an insulation layer, consisting of, from the inside out, aluminum silicate fiber felt (50mm thick), rigid polyurethane foam (80mm thick), and a protective shell made of color steel plate. The circulating water tank 4 is also made of stainless steel and covered with an insulation layer to reduce heat loss during heating. The top sealing cap of the grain soaking tank 1 is also equipped with an insulation layer to further reduce heat escape from the top.

[0048] Example 7 The main difference between this embodiment and Embodiment 1 is that the constant temperature grain soaking device in this embodiment is also connected to a waste heat recovery system.

[0049] Specifically, the exhaust pipe at the top of the circulating water tank 4 is connected to a waste heat recovery heat exchanger to recover the heat from the steam generated during the heating of the soaking water. The waste heat recovery heat exchanger can use the recovered heat to preheat new soaking water, thereby further reducing overall energy consumption. The soaking water discharged after soaking (still at a relatively high temperature) also exchanges heat with new soaking water through the heat exchanger, realizing the cascade utilization of waste heat.

[0050] Validation data To verify the technical effects of the present invention, an actual grain soaking experiment was conducted using the apparatus and method described in Example 1, and compared with traditional processes and existing circulating heating schemes. The following description is based on specific experimental examples.

[0051] Experimental conditions settings: Experimental Example 1 (Scheme of Embodiment of the Invention): The apparatus and method described in Embodiment 1 were used. The grain soaking tank was 6m high and 4m in inner diameter. 20 tons of sorghum were added. The soaking water temperature was 75℃ and the soaking time was 12h. The grain was added first and then water was added. Compressed air was used to blow and level the grain. The external circulating water tank was used for circulating heating (water was pumped from the top and water was reinjected in a ring at the bottom).

[0052] Comparison Example 2 (Traditional Process): Using the same size grain soaking tank, the traditional "water first, grain later" feeding sequence, without setting up circulating heating, the grain soaking water temperature is 75℃ (initial), and the grain soaking time is 12 hours.

[0053] Comparison with Example 3 (existing circulating heating scheme): Using the same specifications of grain soaking tank, the traditional "water first, grain later" feeding sequence, an external circulation pipeline is set up but the circulation pipeline is led out from the middle of the side wall of the grain soaking tank, and the return water also returns from the upper middle part of the side wall. No independent circulating water tank is set up, the grain soaking water temperature is 75℃, and the grain soaking time is 12 hours.

[0054] Experimental results: After soaking the grains, samples were taken at different heights (1m, 2m, 3m, 4m, 5m) from the bottom of the soaking tank to determine the moisture content of the grains. The results are as follows:

[0055] In addition, the unit water consumption for experimental example 1 was 1.95 m³. 3 / t, the water consumption of Comparative Example 2 is 2.5m³. 3 / t, the water consumption of Comparative Example 3 is 2.4m³. 3 / t. The water consumption of the present invention is reduced by about 22% compared with the traditional process and by about 19% compared with the existing circulation scheme. The maximum temperature difference inside the tank during the soaking cycle of Experimental Example 1 was 1.5℃, the initial temperature difference of Control Example 2 was more than 10℃, and the maximum temperature difference inside the tank of Control Example 3 was about 4.5℃.

[0056] Data analysis and effect demonstration: The experimental results above show that the moisture range of the present invention is 1.5%, and the standard deviation of moisture is 0.5%, which is significantly better than that of Control Example 2 and Control Example 3. In particular, compared with Control Example 3 (existing circulation scheme), the moisture range decreased from 2.9% to 1.5%, representing a relative improvement of approximately 48%. This improvement is mainly attributed to the synergistic effect of "grain first, water later" and "bottom circulation heating." Grain first, water later, eliminates the initial time difference, and bottom circulation heating effectively compensates for the vertical temperature difference; both are indispensable.

[0057] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

Claims

1. A method for soaking grains at a constant temperature, characterized in that, Includes the following steps: Put the grain to be soaked into the soaking container (1); Compressed air is used to blow the surface of the grain layer inside the grain soaking tank (1) to make the surface of the grain layer basically flat. After feeding and purging, soaking water is poured into the soaking tank (1) so that all grains can come into contact with water at the same time. After the grain is submerged in the soaking water, the soaking water is drawn from the top of the soaking tank (1) to the external circulating water tank (4), and heated to the target soaking water temperature in the circulating water tank (4); The heated soaking water is evenly re-injected into the soaking tank (1) from the bottom circumferential direction, so that the hot water passes through the grain layer from bottom to top; The extraction process continues throughout the entire soaking cycle. heating The cycle of refilling continues until the soaking process ends.

2. A constant-temperature grain soaking device for implementing the method of claim 1, characterized in that, include: Food soaking container (1); Feeding device (2) is set on top of grain soaking tank (1) and is used to feed grain into grain soaking tank (1). Compressed air purging device (8) is installed on the top of grain soaking tank (1) to purge the surface of grain layer after feeding and before water is added. The top water inlet device (3) is used to inject soaking water into the soaking tank (1) after the grain is fed; The circulating water tank (4) has its inlet connected to the upper part of the grain soaking tank (1) through the first pipeline, and is used to receive the soaking water in the upper part of the grain soaking tank; Heating unit (5) is installed in the circulating water tank (4) or connected to the circulating pipeline of the circulating water tank (4) to heat the soaking water to the target temperature; The bottom water distribution device (6) is located at the bottom of the grain soaking tank (1) and is connected to the outlet of the circulating water tank (4). The bottom water distribution device (6) has multiple water outlets distributed around the bottom of the grain soaking tank (1) to re-inject the heated grain soaking water into the tank in a uniform circumferential manner.

3. The constant temperature grain soaking device according to claim 2, characterized in that, The bottom water distribution device (6) is a ring pipe (7), which is arranged around the bottom of the grain tank (1) and has multiple water outlets.

4. The constant temperature grain soaking device according to claim 2, characterized in that, The top water inlet device (3) is an annular water inlet pipe (9) installed on the upper part of the grain soaking tank (1), and the annular water inlet pipe (9) has water outlet holes around the tank wall.

5. The constant temperature grain soaking device according to claim 2, characterized in that, The purging angle of the compressed air purging device (8) is 15° to 45° with the horizontal plane, and the purging air pressure is 0.3 to 0.6 MPa.

6. The constant temperature grain soaking device according to claim 2, characterized in that, It also includes a temperature detection unit (13) and a control unit (14). The temperature detection unit (13) is at least located at the bottom and top of the grain soaking tank (1). The control unit (14) controls the working state of the heating unit (5) and the circulation pump according to the feedback signal of the temperature detection unit (13) so that the return water temperature of the circulating water tank (4) is maintained within the preset target range.

7. The constant temperature grain soaking method according to claim 1, characterized in that, In the step of uniformly re-injecting the heated soaking water into the tank from the bottom of the soaking tank (1), the uniform water distribution is achieved through the annular pipe (7) at the bottom of the soaking tank (1) and multiple water outlets on the annular pipe (7).

8. The constant temperature grain soaking method according to claim 1, characterized in that, The compressed air purging pressure is 0.3 to 0.6 MPa, and the purging time is 30 to 60 seconds.

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