A gravity flow indirect cooler and cooling method

Abstract

The present invention belongs to the field of material cooling, and specifically relates to a gravity flow indirect cooler and cooling method. The present invention introduces dry gas into the main body of the heavy cooler through a fluidizing air gas distribution component, so that the material in the material fluidization section is in a fluidized state, and the gas is ensured to pass through the material evenly upward, so that the material fed from the feed port is quickly spread in the horizontal direction, and after forming a uniform particle distribution on the cross section of the cooler, the material moves down evenly as a whole through the gravity cooling section, eliminating the uneven cooling caused by material segregation and different cooling speeds of materials at different locations; and the material is fluidized by dry gas, which can more effectively remove the hot and humid gas brought in with the material and the moisture in the pores or cavities on the surface of the material particles, and avoid the material from scarring on the surface of the heat exchanger component. The present invention can make the material cool more evenly, the moisture content of the material at different locations is more uniform, and it helps to improve the problems of compaction and agglomeration during product storage and transportation.

Description

Technical Field

[0001] The invention relates to the field of material cooling, and in particular to a gravity flow type indirect cooler and a cooling method. Background Art

[0002] Obtaining products through microbial fermentation is one of the main production methods in the biochemical industry. Due to the complex composition of the fermentation broth, which contains a variety of organic and inorganic metabolites, various impurities are inevitably present in the main and by-products obtained from the post-processing of the crude fermentation broth, resulting in adhesion and hardening of the products during storage and transportation, reducing product quality and increasing transportation and fertilization costs. Crystallized products produced by fermentation often contain crystal water, which has poor stability when under pressure or heat, or has hygroscopic properties. Therefore, when stored for a long time, the particles will fuse with each other, which is also prone to cause the same problem.

[0003] Generally speaking, the powder and granular products of fermentation plants need to be dried in different forms of dryers to reach the qualified moisture content, and then cooled to near room temperature by cooling equipment such as fluidized bed and rotary drum before packaging and shipment. However, for cooling equipment such as fluidized bed and rotary drum, since the air is in direct contact with the material, moisture will also enter the material from the air while the material is being cooled; or because the material cooling process is not thorough, heat and moisture will still migrate between the inside and surface of the material particles, and between the surface of the particles and the air in the surrounding gaps after cooling, which will eventually lead to agglomeration and compaction. In order to avoid product agglomeration, the current tendency is to reduce the moisture content of the product to a level far below the equilibrium moisture content under ambient conditions during the drying process. Based on the fact that fermented products are prone to moisture absorption, ambient air, especially ambient air in hot and humid seasons, is used as a refrigerant. While the material is being cooled, moisture in the air will also enter the material, causing the material to absorb moisture. There are certain gaps between the particles of the bulk material. The humid air filling the gaps enters the closed environment of the packaging bag. The moisture absorption process on the surface of the particles will also cause further adhesion of the particles. If the temperature of the packaged material is higher than the ambient temperature, the moisture inside the particles will continue to migrate to the surface and be released into the gaps during the process of the material continuing to dissipate heat to the environment, which will continue to increase the humidity of the air and cause adhesion between the particles. Therefore, for equipment where materials are directly contacted with air for cooling, it is necessary to deeply dehumidify the air to prevent the materials from absorbing moisture during the cooling process, and replace the air in the gaps between the material particles with dry air; due to the efficiency of the cooling equipment, in order to cool the materials to the ambient temperature (for example, to cool the materials to below 25-35°C in summer), a lower inlet air temperature and a lower relative humidity at the inlet air temperature are required (for example: dry bulb temperature 20°C, relative humidity 20%), but the air is humid in summer and autumn, and the energy consumption of the dehumidification and cooling process is relatively large, sometimes even accounting for more than 20-30% of the energy consumption of the drying process. In addition, during the cooling process, the particles are in a state of violent motion, and the friction between the particles and between the particles and the wall of the cooling equipment will cause the particles to wear, and the friction will generate new dust that enters the product, reducing the product quality and increasing the degree of product agglomeration.

[0004] In recent years, the fertilizer industry, especially the urea industry, has begun to introduce cooling devices for indirect heat transfer of bulk solid materials from the international market. Compared with fluidized bed coolers, they have obvious technical advantages in energy saving, emission reduction, cooling depth, etc. The main body of this cooling device is a vertically arranged container, which is divided into three parts from top to bottom: feeding section, cooling section and discharging section. The cooling section is equipped with a heat exchanger; free-flowing solid particles enter the container from the inlet of the feeding section and move slowly from top to bottom under the action of gravity. When flowing through the cooling section, they flow through the external channel of the heat exchanger set in this part. The heat is taken away by the refrigerant in the heat exchanger and the material is cooled to the required temperature, and then enters the shell of the discharging section and is discharged from its outlet. Since the material is in a slow overall flow state during the cooling process, the friction between particles and between particles and the wall surface is very small, and particle wear is basically eliminated. And because it is an indirect heat transfer method, the material is basically not in contact with the air, which avoids the increase of the water content of the product during the cooling process.

[0005] However, when processing powdered and granular products in fermentation plants, whether they are crystalline products or granular products made by granulating and drying a mixed liquid with multiple ingredients, there are some common problems when using gravity flow coolers for cooling:

[0006] (1) After the material absorbs moisture, it is easy to form scars on the heat exchange wall of the heat exchanger, especially the wall of the heat exchanger located above the gravity flow cooler, which will cause a significant decrease in the heat exchange effect. In severe cases, it will also cause partial blockage of the material flow channel. In addition, the material itself will also form lumps after absorbing moisture.

[0007] (2) In a gravity flow cooler, it is always expected that the material flows downward at a uniform speed over the entire cross section of the cooler, that is, moves downward in the so-called overall flow, so as to obtain the best cooling effect. However, the actual application is not always so ideal, especially for materials that are easy to absorb moisture, agglomerate, and scab. The agglomeration and scab of the material aggravate the unevenness of the overall flow of the material, making the degree of cooling of the material in different areas on different cross sections of the cooling equipment more different. This leads to some materials still having high temperatures. Even if the average discharge temperature meets the requirements, these materials may still become hardened during long-term storage.

[0008] The above problems restrict the application and promotion of gravity flow coolers in the fermentation industry or industries with similar material characteristics, making it impossible for them to replace traditional mature direct contact cooling devices such as fluidized beds and rotary drums.

[0009] Chinese patent document CN110701927A (201910776877.2) discloses a material cooling system based on a powder flow cooler. Although the above-mentioned material cooling system can effectively avoid the scarring of the wall of the powder flow cooler and the agglomeration of the material during the cooling process, since the above-mentioned material cooling system needs to increase the temperature of the coolant in the powder flow cooler to reduce the temperature difference between the coolant and the material in the powder flow cooler, the temperature of the coolant must be greater than the dew point value of the material. However, the material after drying is usually still at a relatively high temperature, and it is impossible to use a coolant at a lower temperature to cool the material, resulting in a decrease in the overall cooling efficiency. In addition, the dry air introduced into the material cooling system will gather upward after absorbing the moisture in the material, and the material fed into the material cooling system contains a large amount of hot and humid gas, which makes the upper material at the top of the material cooling system have a relatively high humidity. In order to avoid scarring, it is necessary to further increase the entry temperature of the coolant in the upper powder flow cooler, resulting in a further decrease in the overall cooling efficiency. Summary of the invention

[0010] The main purpose of the present invention is to provide a gravity flow indirect cooler and cooling method. The present invention arranges a material fluidization section and a gravity cooling section from top to bottom in the main body of the recooler, and introduces dry gas into the main body of the recooler through a fluidizing air gas distribution component, so that the material in the material fluidization section is in a fluidized state, and the gas is ensured to pass through the material evenly upward, so that the material fed from the feed port is quickly spread in the horizontal direction, and after forming a uniform particle distribution on the cross section of the cooler, it moves downward evenly as a whole through the gravity cooling section, thereby eliminating the material segregation and the uneven cooling caused by the different cooling speeds of the material at various locations; and the material is fluidized by dry gas, which can more effectively remove the humid and hot gas brought in with the material and the moisture in the capillaries or cavities on the surface of the material particles, so that the material after the fluidizing air replacement is in a dry gas environment and enters the indirect cooling process, thereby avoiding the material from scarring on the surface of the heat exchanger component, ensuring that the material is cooled more evenly, and the moisture content of the material at various locations is more uniform, which is helpful to use a lower temperature refrigerant to cool the material, improve the cooling efficiency, and help to improve the problems of hardening and agglomeration during product storage and transportation.

[0011] The technical problem to be solved by the present invention is achieved by adopting the following technical solution: A gravity flow type indirect cooler comprises a heavy cooler body, a gas distribution component, a heat exchanger component, a gas supply system and a heat exchange medium supply system;

[0012] The heat exchanger assembly is a plate heat exchanger or a tube heat exchanger, and a first material channel running vertically is provided between the heat exchange plates or between the heat exchange tubes of the heat exchanger assembly;

[0013] The gas distribution assembly includes an air distribution channel distributed along the cross section of the recooler body, second material channels are arranged outside the air distribution channel and are spaced apart from each other along the cross section of the recooler body, and the side wall of the air distribution channel is provided with air distribution holes communicating with the inner cavity of the recooler body;

[0014] The recooler body is a vertical shell, the top of the recooler body is provided with a feed inlet and an exhaust port, and the bottom of the recooler body is provided with a discharge port;

[0015] The recooler body is provided with a material fluidizing section and a gravity cooling section from top to bottom;

[0016] The gravity cooling section is provided with a heat exchanger assembly connected to a heat exchange medium supply system;

[0017] The heat exchange medium supply system is used to provide refrigerant to the heat exchanger assembly;

[0018] The gas distribution assembly includes a fluidizing air gas distribution assembly arranged in the material fluidizing section, and the fluidizing air gas distribution assembly is connected to the gas supply system;

[0019] The fluidizing air gas distribution assembly is used to introduce dry gas into the main body of the recooler, so that the material in the material fluidization section is in a fluidized state, and the material entering the material fluidization section is spread out in the horizontal direction to ensure that the material particle size is evenly distributed and the moisture in the material gap is fully replaced and discharged before entering the gravity cooling section. The material layer in a fluidized state can effectively eliminate the feed cone, so that the bed material surface tends to the same horizontal plane, and also eliminates the feed segregation phenomenon. And when the material is in a fluidized state, the dry gas can more effectively remove the humid and hot gas in the gap between the material particles, so that the replaced material is in a uniform dry gas environment, and the dew point temperature is much lower than the refrigerant temperature, so a lower temperature refrigerant can be used to cool the material to improve the cooling efficiency; the high mass transfer rate in the fluidized state can also replace the gas in the cavitation and capillary pores on the particle surface to a certain extent, so that the moisture in the material is further taken out, which plays a role in deep drying.

[0020] The dry gas introduced is preferably dry cold gas, which has the effect of cooling the material while performing dry gas replacement, further improving the cooling efficiency; the dry gas is the gas after moisture is removed, and the dry cold gas is obtained by cooling the dry gas.

[0021] Preferably, when the fluidizing air distribution assembly works independently, the fluidizing air velocity generated by the ventilation volume of the fluidizing air distribution assembly is 1 to 6 times the critical fluidizing velocity calculated based on the average particle size of the material. That is, the fluidization number of the material in the material fluidization section is between 1 and 6, so that the material is in a sufficient and uniform fluidization state, and the wet steam contained in the gas in the gap of the material is brought out to avoid the blockage of the material flow in the local area.

[0022] The above-mentioned fluidization wind speed refers to the operating wind speed when the material is in a fluidized state. In this patent, it specifically refers to the operating wind speed formed by the total air volume passing through the material fluidization section, which is the average wind speed passing through the cross section calculated according to the horizontal net cross-sectional area of ​​the material fluidization section.

[0023] In the present invention, the fluidization air volume should be selected so that the lower limit of the fluidization wind speed is not lower than the critical fluidization speed calculated according to the average particle size of the material. Specifically, the lower limit of the fluidization wind speed is to ensure that the material is in a fluidized state for sufficient loosening, flow, mutual mixing and other movements, so as to eliminate the feed cone, make the upper surface of the material layer generally at the same level, make the material layer generally in a fluidized boiling state, and avoid the minimum operating wind speed of local material flow blockage. The upper limit of the fluidization wind speed is the maximum wind speed that maintains stable fluidization of the material layer without excessive entrainment, which can be considered with reference to the upper limit of the operating gas speed of the usual fluidized bed.

[0024] From the perspective of eliminating the feed cone by fluidizing and flowing the material, this can be achieved when the operating wind speed is close to the critical fluidization speed within a certain range from low to high (for example, for a 70% lysine granulation product, the feed cone can be basically eliminated when the operating wind speed is 0.7 to 1 when the fluidization number is 0.7), but this partial and insufficient fluidization cannot meet the requirements of the present invention. Because most industrial products have a certain particle size distribution range, the average particle size is uniformly used in engineering to calculate the critical fluidization speed, and the range of the operating wind speed (i.e., the actual value of the wind speed during production operation) is determined accordingly. In the present invention, when the operating gas velocity is determined according to the average particle size, for materials with a wide particle size distribution, when the fluidization number is below 1 but close to 1, a small part of the material below the average particle size is already in a bubbling fluidized state, while the particles with larger particle sizes are still in a static state, and this local fluidized area is randomly scattered over the entire cross-section of the box; in the material cone area above the material layer, due to the driving force of the rising bubbles and the flowing particles, the feed cone can be basically eliminated under the action of the gravity of the material pile itself, thereby achieving the purpose of making the bed tend to be basically horizontal; however, due to the air flow short-circuiting caused by this so-called "local fluidization" or "semi-fluidization", local material flow blockage, and uneven distribution of air holes (only distributed at the gas distribution pipe, and the gas distribution pipes are material flow channels) and other reasons, the humid air in the material in the non-fluidized area is more difficult to discharge; the existence of the moisture absorption and agglomeration characteristics of the material makes the material in the static state in the non-fluidized area more prone to moisture absorption, agglomeration or scarring. Therefore, in the present invention, it is not advisable for the operating wind speed to be lower than the critical fluidization velocity calculated based on the average particle size.

[0025] Preferably, the gravity cooling section is provided with multiple layers of heat exchanger components from top to bottom, each layer of heat exchanger components forms a cooling section, and the temperature of the refrigerant of each layer of heat exchanger components decreases from top to bottom. Multiple layers of heat exchanger components are provided from top to bottom to provide refrigerants of different temperatures to different cooling sections, and the technical significance is as follows:

[0026] a. Powdered and granular materials generally contain a small amount of moisture and have a certain degree of hygroscopicity. Under equilibrium conditions, materials at a certain temperature correspond to a certain critical relative moisture content of the gas in the gap between particles and the corresponding critical dew point temperature. When the relative moisture content value or dew point temperature of the gas is higher than the critical value, the moisture will migrate from the gas to the material, and the material will absorb moisture. In the gravity cooling section, the material layer can be regarded as a fixed bed that moves slowly along a fixed flow channel in an aerated state. As the material moves downward, the material temperature gradually decreases, and the corresponding critical relative moisture content value and critical dew point value gradually decrease. The material at the end (lower end) of different cooling sections is cooled to a certain temperature, which requires that the refrigerant temperature of each cooling section must be higher than a corresponding temperature to ensure that the relative moisture content and dew point temperature of the gas environment around the particles are lower than the critical value to avoid moisture absorption by the material.

[0027] When dry air with different dehumidification degrees is introduced into different cooling sections, while satisfying the condition that the material does not absorb moisture, it is also necessary to prevent the gas near the heat exchange wall from being cooled to a temperature close to the wall surface, where its relative humidity quickly rises to a saturated state and condenses on the wall surface, so as to avoid moisture absorption, agglomeration or scarring on the heat exchange wall or in the local material layer near the wall surface.

[0028] If a refrigerant of uniform temperature is used to enter each layer of the heat exchanger assembly in parallel, the temperature difference between the material and the refrigerant in the upper to middle cooling section is too large. Based on the above reasons, the probability of moisture absorption and scarring is relatively high. When the refrigerant is operated in series from bottom to top in countercurrent, since the heat transfer rate between the material layer and the wall surface is very low and the refrigerant flow rate is very large, the temperature rise of the refrigerant passing through the single-layer heat exchanger assembly is still relatively low, and the temperature difference between the material and the refrigerant is also relatively large, so the probability of moisture absorption and scarring is still relatively high. In order to avoid this phenomenon, in the present invention, the gravity cooling section is divided into multiple cooling sections, i.e., multi-layer heat exchanger assemblies, and refrigerants of different temperatures are introduced respectively. The material temperature is higher at the inlet of the heavy cooler body, and a higher temperature refrigerant is introduced into the heat exchanger assembly. As the material temperature decreases, a lower refrigerant temperature is used, thereby limiting the temperature difference between the material and the refrigerant to a certain range, thereby avoiding the occurrence of this phenomenon.

[0029] b. Refrigerants of different temperatures are introduced into each layer of heat exchanger components. When the material temperature is higher, ordinary refrigerants with lower costs, such as circulating water provided by the factory's public works, are used. When the material temperature is lower, cryogenic water refrigerants with higher costs are used, thereby saving production costs.

[0030] Preferably, each layer of the heat exchanger assembly of the present invention adopts an independent heat exchange medium supply system, and the heat exchange medium supply system can independently control the flow rate and / or temperature of the refrigerant in the heat exchanger assembly to which it is connected. Each layer of the heat exchanger assembly is provided with an independent refrigerant supply system, and the flow rate and / or temperature of the refrigerant can be independently adjusted. The purpose is: the refrigerant temperature can be flexibly adjusted to ensure that the refrigerant temperature is higher than the temperature at which the material absorbs moisture and adheres, and to avoid scarring on the surface of the cooler, i.e., the heat exchanger assembly.

[0031] Preferably, the gas distribution assembly of the present invention further comprises a replacement wind gas distribution assembly arranged in the gravity cooling section, and the replacement wind gas distribution assembly is connected to the gas supply system;

[0032] The replacement air gas distribution assembly is used to introduce dry gas into the main body of the heavy cooler, so that the material layer is in an aerated state and the gas in the gaps between the particles is replaced, taking away the evaporated (volatile) moisture in the gas and the particles, reducing the relative humidity and dew point temperature of the gas environment in which the particles are located, so that a lower temperature refrigerant can be used to cool the material; the material in the aerated state can maintain good fluidity, so that the material is in a state of overall downward movement in the corresponding cooling section; the dry gas is preferably dry cold gas, which also has the effect of cooling the material and improves the cooling efficiency;

[0033] A layer of replacement wind gas distribution assembly is arranged under each layer of heat exchanger assembly.

[0034] Multiple layers of heat exchanger components are arranged from top to bottom, and a layer of displacement wind gas distribution component is arranged under each layer of heat exchanger components. The technical significance is as follows:

[0035] a. During the start-up phase, a certain amount of "bottom material" needs to be added to bury all the heat exchanger components in the material layer before normal production can be put into operation. During the process of adding the "bottom material", the discharging device is in a stopped or slow discharging state. As the feeding process proceeds, the material layer gradually rises; when the material layer is within the height range of the bottom heat exchanger component, the displacement wind gas distribution component below it is turned on. When the material layer rises to the height range of the second-to-last heat exchanger component, the second-to-last set of displacement wind gas distribution components is turned on, and the first-to-last displacement wind gas distribution components are closed or turned down, and so on, until the material reaches the operating level, the highest layer of fluidizing wind gas distribution components is turned on, and the system enters normal operation. This operation ensures that the moisture in the material is fully and reliably replaced with dry gas during the start-up to stable operation.

[0036] b. During the shutdown phase, the reverse order is adopted, and the gas distribution components at the lower position are opened and the gas distribution components at the higher position are closed in turn as the material layer decreases. This operation ensures that the moisture in the material is fully and reliably replaced with dry gas during the shutdown period.

[0037] c. In normal production, you can choose not to open, open one layer, open multiple layers, or all of the replacement wind gas distribution components according to the material characteristics and operation requirements. For example, for some materials, when the material temperature is high in the upper area of ​​the cooling section, a small amount of moisture will still evaporate, while when the material temperature is low in the middle and lower areas of the cooling section, moisture evaporation will stop. At this time, the upper gas distribution component should be opened without opening the lower gas distribution component; some materials need to be cooled to a very low temperature, and drier gas needs to be added to adapt to the lower temperature refrigerant. At this time, only the lower gas distribution component can be opened; some materials have poor fluidity, and they should maintain an appropriate inflation state throughout the cooling process to increase fluidity. At this time, all gas distribution components can be opened to introduce a small amount of dry gas; and for materials with good fluidity and no steam precipitation throughout the process, even no ventilation is required.

[0038] When multiple groups of gas distribution components are turned on, the replacement air volume of the cooling section at the top is the sum of the ventilation volumes of all the opened gas distribution components at the bottom; similarly, the fluidizing air volume of the material fluidizing section at the top is the sum of the ventilation volumes of all the gas distribution components below it; and the actual operating wind speed of the material layer where the material is located (the fluidizing wind speed in the fluidizing section) is generated by all the air volumes in the cross-section of the material layer.

[0039] d. In practical applications, for materials with less obvious moisture absorption and scarring characteristics, the gas distribution components (including fluidized air gas distribution components and displacement air gas distribution components) can be fed with gases of different dryness from top to bottom in sequence, as long as their dew point temperature is lower than the refrigerant inlet temperature of the cooling section where they are located to a certain extent, thereby further saving energy consumption and equipment costs for gas dehumidification. The dryness of the dry gas should ensure that no condensation occurs on the wall of the heat exchanger component where the refrigerant with the lowest temperature in the cooling section of the layer is located, and at the same time ensure that the material does not absorb moisture, agglomerate or scar when it is cooled by the wall of the heat exchanger component where the refrigerant with the lowest temperature is located.

[0040] Preferably, when the replacement air distribution assembly is partially or fully operational, the operating wind speed generated by the ventilation volume or the sum of the ventilation volumes of the replacement air distribution assembly is the average wind speed through the cross section calculated according to the horizontal net cross-sectional area of ​​the gravity cooling section, and the operating wind speed is 0 to 0.5 times the critical fluidization velocity calculated according to the average particle size of the material;

[0041] When the fluidizing wind gas distribution assembly and the replacement wind gas distribution assembly are working simultaneously, the fluidizing wind speed generated when the ventilation volume of the fluidizing wind gas distribution assembly is calculated separately is not less than 0.7 times the critical fluidizing speed calculated according to the average particle size of the material; the fluidizing wind speed generated by the sum of the ventilation volumes of the fluidizing wind gas distribution assembly and the replacement wind gas distribution assembly is not less than 1.2 times the critical fluidizing speed calculated according to the average particle size of the material.

[0042] After the material passes through the upper fluidizing section, most of the wet gas has been displaced out of the material gap and is in a relatively dry gas environment. At this time, only a small amount of dry gas needs to be introduced into the recooler body through the displacement wind gas distribution component to bring out the small amount of moisture volatilized in the material; when selecting a variety of dry gases with different dryness, the lower displacement wind gas distribution component can choose to introduce drier gas than the dry gas introduced by the upper gas distribution component to further reduce the dew point of the gas environment in the material gap, and correspondingly, a lower temperature refrigerant can be used. The introduced dry gas not only brings out the wet steam, but also improves the fluidity of the material.

[0043] The maximum operating wind speed generated by the ventilation volume or the sum of the ventilation volumes in the gravity cooling section should use a lower value as much as possible when meeting the operating requirements. The fluidization number is best between 0 and 0.5. On the one hand, when the gas velocity is low, the resistance of the gas passing through the material layer is very low, and the power consumption of gas pressurization is small. On the other hand, when the operating gas velocity is close to the critical fluidizing gas velocity, the so-called "local fluidization" or "semi-fluidization" phenomenon will occur, causing defects such as gas short-circuiting, which in turn aggravates the gravity flow blockage in the unfluidized area, destroying the uniformity of the overall flow of the material layer flowing downward by gravity, thereby reducing the cooling effect.

[0044] Preferably, the material fluidizing section is provided with a heat exchanger assembly connected to a heat exchange medium supply system;

[0045] The heat exchange medium supply system is used to provide refrigerant to the heat exchanger assembly in the material fluidization section. By arranging the heat exchanger assembly in the material fluidization section, the heat transfer coefficient can be significantly improved by exchanging heat between the heat exchanger assembly and the material in a fluidized state, thereby improving the cooling efficiency. In addition, by fluidizing the material, the wall surface of the heat exchanger assembly can be continuously flushed with the material, further avoiding scarring on the surface of the top heat exchanger assembly and improving the heat exchange efficiency.

[0046] The present invention preferably further comprises an auxiliary silo, the inlet of which is connected to the discharge port, and the outlet of which is connected to the feed port. The present invention is provided with an auxiliary silo for quickly filling the main body of the recooler during the start-up process, so that the material reaches the material level above the heat exchanger assembly, shortening the start-up process. It can also be used as a temporary storage container during equipment failure inspection and repair to temporarily store the material after cooling.

[0047] Preferably, the auxiliary silo is located above the main body of the recooler, and can use gravity to feed materials into the main body of the recooler.

[0048] Preferably, the present invention further comprises a material level meter and a discharger with adjustable flow rate;

[0049] The material level meter is arranged on the top of the recooler body and is used to measure the material level height of the material in the recooler body;

[0050] The discharger is connected to the discharge port and is used to adjust the discharge speed of the material to control the material level height in the recooler body. The discharger is used to control the uniform discharge of the material, and the flow rate can be adjusted. The discharge flow rate of the discharger is controlled by the material level electrical signal of the material level meter to control the material level height in the recooler body, ensure a certain fluidized material layer to maintain stable fluidization, and at the same time, the material buries all the heat exchanger components to ensure heat exchange efficiency.

[0051] Preferably, the gas supply system includes a gas dehumidification device and / or a cooling device, and the heat exchange medium supply system includes a fluid cooling device;

[0052] The gas dehumidification equipment is used to remove moisture from the gas and obtain dry gas, the gas cooling equipment is used to control the temperature of the dry gas, and the fluid cooling equipment is used to control the temperature of the refrigerant to prevent the material from absorbing moisture, agglomerating, or scarring on the wall of the heat exchanger. For example, the refrigerant inlet temperature of each heat exchanger component can be controlled to be higher than the material moisture absorption temperature of the material on the material side of the corresponding heat exchanger component to avoid moisture absorption, agglomeration, and scarring. At the same time, the moisture content of the dry gas can be controlled to reduce the dew point temperature of the gas on the material side, and then the inlet temperature of the refrigerant can be controlled to be lowered to a lower temperature for cooling, thereby improving the cooling efficiency.

[0053] Preferably, the heat exchanger assembly includes a plurality of heat exchange tubes arranged at intervals in the horizontal direction, and the heat exchange tubes are serpentine tubes extending up and down;

[0054] Two adjacent serpentine heat exchange tubes are arranged in an up-and-down staggered manner.

[0055] Compared with the horizontally extended serpentine tube layout, the vertically extended serpentine tube layout is conducive to forming a vertically penetrating material flow channel, reducing the resistance of the material flowing down, and forming countercurrent or parallel heat exchange between the material and the refrigerant, rather than cross-current heat exchange, with higher heat exchange efficiency, and it is not easy for the material to have a temperature difference at different positions in the same horizontal section. The two adjacent serpentine heat exchange tubes are arranged in a staggered manner, which increases the number of diversions and confluences of the material in the internal flow channel of the heat exchanger assembly, increases the disturbance on the material side, and can increase the heat transfer coefficient on the material side; at the same time, increasing the flow of the material also helps to reduce the slight bonding of the material.

[0056] Preferably, the gas distribution assembly comprises a plurality of gas distribution pipes arranged horizontally and spaced apart from each other, and the air distribution holes are arranged below the gas distribution pipes;

[0057] The air distribution holes are arranged in rows along the axial direction of the gas distribution pipe, and at least one row of air distribution holes is arranged under each gas distribution pipe;

[0058] The gas distribution pipe is a straight pipe, and the gas distribution pipe is perpendicular to the heat exchange pipe in the heat exchanger assembly or the gas distribution pipe is perpendicular to the heat exchange plate in the heat exchanger assembly, that is, the horizontal extension direction of the gas distribution pipe is perpendicular to the horizontal extension direction of the heat exchange pipe or the heat exchange plate. By opening one or more rows of air distribution holes in the axial direction in the lower half of each gas distribution pipe, the gas in the pipe is sent to the material channel inside the box; the arrangement of the gas distribution pipe and the opening of the hole on the pipe wall can ensure that the gas is evenly diffused to the entire cross-section of the shell and passes through the material layer upward; the cross-sectional shape of the gas distribution pipe can be circular, or elliptical, rhombus, flat rectangular or other shapes, and the shape of the air distribution hole is not only circular, but can be strip-shaped gaps or other shapes.

[0059] The arrangement of the gas distribution pipe extending in the horizontal direction perpendicular to the horizontal extension direction of the heat exchange tube or heat exchange plate is conducive to a more uniform distribution of gas in the heat exchange tube or heat exchange plate area, avoiding poor material fluidization or local blockage caused by insufficient local airflow.

[0060] The present invention also discloses a cooling method, using the gravity flow indirect cooler, comprising the following steps:

[0061] S1. Use materials to completely bury the heat exchanger components in the main body of the recooler;

[0062] S2. Use the gas distribution component to introduce dry gas into the recooler body, so that the material in the material fluidization section is in a fluidized state, ensuring that the material is evenly distributed in the cross section of the recooler body, and enters the gravity cooling section in this evenly distributed state. At the same time, use fluidization to fully replace the moist gas between the material particles with dry gas, and bring the moisture in the moisture and the moisture precipitated in the material out of the recooler body; the moisture content of the material is the largest when feeding, and the characteristics of the fluidized state are used to bring the moisture in the material out of the recooler body at the top, which can effectively avoid scarring of the heat exchanger components below;

[0063] S3. Use the heat exchanger components of the gravity cooling section to cool the material, and control the refrigerant inlet temperature of each heat exchanger component to be higher than the moisture absorption, agglomeration or scarring temperature of the material on the material side of the corresponding heat exchanger component.

[0064] Preferably, in step S1, the method of using materials to completely bury the heat exchanger components in the recooler body is:

[0065] S11, a gas distribution assembly is arranged at the upper end of the recooler body;

[0066] Before cooling the material to be cooled, the cooled material is quickly added to the recooler body to a preset height; the preset height is higher than the gas distribution assembly;

[0067] S12, using the gas distribution component to introduce dry gas, so that the material above the gas distribution component is in a fluidized state;

[0068] S13, then, continuously feeding the material to be cooled into the recooler body from the feed inlet at the top of the recooler body;

[0069] The above method can simplify the complexity of operations from start-up to stable operation, and achieve faster start-up.

[0070] Preferably, in step S1, the method of using materials to completely bury the heat exchanger components in the recooler body is:

[0071] S11, multiple layers of gas distribution components are sequentially arranged from top to bottom inside the recooler body, and the material to be cooled is continuously fed into the recooler body;

[0072] S12, while feeding the material, when the material level rises to the lowest gas distribution component, start the lowest gas distribution component and introduce dry cold gas to make the material above the gas distribution component enter a fluidized state;

[0073] S13. When the material level reaches the upper gas distribution component, close or turn down the lower gas distribution component, and open the upper gas distribution component to continue to introduce dry gas, and at the same time, introduce refrigerant into the heat exchanger component between the lower gas distribution component and the upper gas distribution component to cool the material.

[0074] The above operations are performed upwards in sequence until the material level reaches a preset height, and finally a material fluidization section and a gravity cooling section arranged up and down are formed.

[0075] The above method ensures that during the period from start-up to stable operation, that is, during the period when the internal space of the recooler is filled with the material to be cooled at a normal production speed, the moisture in the material and the moisture in the space that has not been filled are fully and reliably replaced with dry gas, and the material to be cooled used for filling is cooled to the discharge temperature in a dry gas environment and then continuously discharged, thereby ensuring that the cooling effect of stable production is achieved throughout the start-up process.

[0076] Working principle of the present invention:

[0077] Dry gas is blown into the shell of the recooler through the fluidizing air gas distribution main pipe, so that the materials above the fluidizing air gas distribution pipe are fluidized. The characteristics of the gas-solid fluidization phenomenon are used to pre-treat the materials coming from the drying process as follows:

[0078] a. Eliminate the feed cone and segregation phenomenon during the feeding process, so that the material is evenly distributed within the cross-section of the recooler body.

[0079] In theory, it is always hoped that the material moves downward in the box of the gravity flow indirect cooler (referred to as the heavy cooler) in an overall flow manner, so that the material on the entire cross section undergoes the same cooling process, thereby obtaining a uniform and consistent cooling depth. However, actual powdery or granular materials always have a certain particle size distribution range. When the material falls freely from the feed port to the stationary heat exchanger component or the upper part of the material at a certain speed, a conical material accumulation area will be formed, namely: the feed cone; after the feed cone is formed, the subsequent particles will appear in the process of falling. Large particle size materials are enriched at the periphery of the cone, and small particle size and powdery materials are enriched in the center, namely: particle segregation. The weight of the feed cone and the impact force of the feed exert uneven pressure on the material below it, causing the material in the central area of ​​the feed cone to move down quickly while the material around it moves down slowly, affecting the uniformity of the overall flow of the material, thereby causing differences in the cooling depth of materials in different box cross-sectional areas. Since the materials moving downward in the recooler in an overall flow manner have the same cooling time, when segregation occurs, uneven material particle size distribution will appear on the cross-section of the recooler body box, and the coarse particles will cool slower than the fine particles. This uneven cooling rate will cause the material temperature around the material cone to be higher than the material in the center area, thereby exacerbating the cooling temperature difference.

[0080] The present invention sets a material fluidizing section above the recooler body. In the fluidized state, the material has fluid-like characteristics, the feed cone is automatically eliminated, and a horizontal upper surface of the fluidized bed is formed, so that uniform material pressure is generated on the entire cross-section of the recooler body, which is beneficial to the overall flow of the material from top to bottom in the gravity cooling section box, and increases the uniformity of the cooling time of the material at various locations in the cross-section of the recooler body; further, in the fluidized state, the particle size distribution of the material in the horizontal direction is uniform, and there is no material segregation phenomenon, thereby ensuring that the material enters the subsequent cooling process with a uniform particle size distribution, eliminating the uneven cooling caused by different feed particle size distributions.

[0081] b. Efficiently replace the hot and humid gas in the gaps between material particles, and pre-cool the material and make the moisture even.

[0082] Powdered or granular materials have a certain porosity. After drying, the gaps between the particles of the materials are usually filled with hot and humid gas, which can be common air or inert gas such as nitrogen. The moisture can be common water vapor or steam of other volatile components such as methanol vapor. The relative humidity of moisture in the gas is very low at high temperature, but after cooling, the relative humidity becomes higher, and it is easier to be absorbed by the particles, thereby increasing the moisture in the particles, that is, the material absorbs moisture. When the temperature of the humid gas drops below the dew point temperature of the moisture, it will condense on the surface of the particles and the wall of the heat exchanger. In particular, the temperature of the heat exchanger wall and the vicinity is very low, and the humid gas is more likely to condense, which directly causes the material to agglomerate or the heat exchanger wall to scar. Therefore, the humid hot gas must be replaced for the moisture-absorbing material so that it is in a dry gas environment. The fluidizing gas can play such a role.

[0083] Furthermore, in the fluidized state, the contact efficiency between the particles and the fluidizing gas is very high, and the gas around each particle can be fully replaced; the high mass transfer rate in the fluidized state can also replace the gas in the capillary pores on the surface of the particles to a certain extent; its heat transfer efficiency is also very high, so as to make full use of the thermal energy of the low-temperature fluidizing gas to reduce the temperature of the feed, eliminate the feed temperature and moisture differences between particles with different moisture contents and different particle sizes, and achieve better cooling and moisture homogenization effects.

[0084] In addition, when the gas flow introduced by the fluidizing air gas distribution component of the present invention makes the corresponding material layer in a fluidized bed, the effect of eliminating the feed cone and material segregation is basically independent of the cross-sectional size and shape of the bed. Therefore, a larger cross-sectional area can be used to place a larger heat exchanger component or multiple groups of heat exchanger components in different combinations without worrying about the impact of non-integrated flow and uneven particle size distribution on cooling uniformity caused by the increase in feed cone height. Therefore, a smaller aspect ratio (for a rectangular shell, it can be described as a height-to-width ratio or a height-to-length ratio, or a height-to-cross-sectional area ratio) can be used to obtain a greater material processing capacity, or when the feed amount is the same or the material cooling temperature difference is the same, a lower equipment height can be used, which correspondingly reduces the plant height or the secondary lifting height of the material, thereby increasing investment or energy consumption.

[0085] Compared with the prior art, the present invention has the following beneficial effects: the present invention provides a gravity flow indirect cooler, which performs indirect heat exchange cooling on the dried material by setting a heat exchanger assembly, thereby avoiding contact between the material and the outside air and avoiding wear of the material particles.

[0086] The present invention arranges a material fluidizing section and a gravity cooling section in a vertical recooler body from top to bottom, and arranges a fluidizing air gas distribution component connected to an air supply system in the material fluidizing section, and uses the fluidizing air gas distribution component to introduce dry gas into the recooler body, so that the material in the material fluidizing section is in a fluidized state, and a fluidized material layer is formed in the upper area of ​​the material layer that is in an overall gravity-type slow moving state in the recooler body, so that the material fed into the feed port is evenly spread in the horizontal direction (i.e., the cross section of the recooler body) and evenly mixed with the material below, thereby eliminating the uneven particle size distribution of the material in the cross section of the recooler body, ensuring the overall uniform downward movement of the material, and allowing the material to be evenly cooled by the heat exchanger component when passing through the gravity cooling section, thereby avoiding the agglomeration problem during transportation or storage caused by uneven cooling of the material.

[0087] In addition, dry gas is introduced into the recooler body by utilizing the fluidizing air gas distribution component, so that the material in the fluidizing section is fluidized. While quickly taking away the moist and hot gas carried by the material, the material can be further deeply dried in the fluidized state, so that the material is placed in a dry gas environment, effectively avoiding scarring on the wall of the heat exchanger component and material agglomeration, and achieving uniform moisture content of the material at various locations within the same cross-section of the recooler body, which in turn helps the heat exchanger component to use a refrigerant with a lower temperature, improves the cooling efficiency of the material, and avoids agglomeration problems during transportation or storage caused by uneven moisture content of the material and the temperature difference between the material and the environment. BRIEF DESCRIPTION OF THE DRAWINGS

[0088] Figure 1 This is a schematic structural diagram of the gravity flow indirect cooler described in Example 1 of the present invention;

[0089] Figure 2 This is a schematic structural diagram of the gravity flow indirect cooler described in Example 2 of the present invention;

[0090] Figure 3 This is a schematic structural diagram of the gravity flow indirect cooler described in Example 3 of the present invention;

[0091] Figure 4 It is a schematic diagram of the positional relationship between the gas distribution component and the heat exchanger component;

[0092] Figure 5 It is a structural schematic diagram of a tubular heat exchanger;

[0093] Figure 6 It is a structural schematic diagram of a plate heat exchanger;

[0094] Figure 7 It is a schematic diagram of the structure of setting gas exchange holes on the heat exchange plate;

[0095] Figure 8It is a schematic diagram of the structure of the gas distribution component in the longitudinal section direction;

[0096] Fig. 9 It is a schematic diagram of the structure of the cross-section direction of the gas distribution component;

[0097] Fig.10 is a schematic cross-sectional view of a gas distribution pipe;

[0098] In the figure, 1 is a recooler body, 2 is a fluidizing air gas distribution assembly, and 3 is a heat exchanger assembly;

[0099] 1000 first material channels, 2000 air distribution channels, 3000 second material channels, 4000 air distribution holes;

[0100] 101 feed port, 102 exhaust port, 103 discharge port;

[0101] 100 material fluidization section, 200 gravity cooling section, 300 gas distribution pipe;

[0102] 4 displacement air gas distribution assembly, 5 auxiliary silo, 6 material level meter, 7 discharger, 8 upper surface of material layer;

[0103] 400 inlet distribution main pipe, 500 outlet distribution main pipe, 600 first connecting pipe;

[0104] 700 gas distribution main pipe, 800 second connecting pipe, 901 heat exchange pipe, 902 heat exchange plate. DETAILED DESCRIPTION

[0105] The technical solutions in the embodiments of the present invention will be described clearly and completely below in conjunction with the accompanying drawings.

[0106] In the present invention, the definition of net cross section is: the cross-sectional area of ​​the material flow channel after deducting the cross-sectional area occupied by the heat exchanger assembly on any horizontal cross-sectional area of ​​the bed layer, i.e., the box where the material fluidization section or the gravity cooling section is located.

[0107] Definition of fluidization number: the ratio of operating wind speed to critical fluidization velocity calculated based on average particle size of the material; the operating wind speed is the average wind speed calculated based on the net cross-section of the box. In the material fluidization section, the fluidization wind speed is generally used to refer to the operating wind speed.

[0108] Calculation method of critical fluidization velocity: Calculate according to the calculation formula given on page 166 of "Fluidized Drying Technology and Equipment" by Tong Jingshan, published by Science Press in 1996.

[0109] Example 1

[0110] like Figure 1 and Figure 4As shown, a gravity flow indirect cooler includes a recooler body 1, a gas distribution component, a heat exchanger component 3, an air supply system and a heat exchange medium supply system (the air supply system and the heat exchange medium supply system are not shown in the figure).

[0111] like Figure 4 , Figure 5 , Figure 6 and Figure 8 As shown, the gas distribution component includes an air distribution channel 2000 distributed along the cross-section of the heavy cooler body 1, and the outer side of the air distribution channel 2000 is provided with a second material channel 3000 distributed along the cross-section of the heavy cooler body 1, and the side wall of the air distribution channel 2000 is provided with air distribution holes 4000 communicating with the inner cavity of the heavy cooler body 1. The gas distribution component is a tubular structure, specifically, including a gas distribution pipe 300 arranged along the cross-section of the heavy cooler body 1 at intervals, the air distribution channel 2000 is the internal channel of the gas distribution pipe 300, and the gas distribution pipe 300 is provided with air distribution holes 4000, and the openings of the air distribution holes 4000 are arranged downward; the gas distribution pipes 300 are straight pipes parallel to each other. As shown Figure 1 As shown, the recooler body 1 is a vertical shell, a feed inlet 101 and an exhaust port 102 are provided at the top of the recooler body 1 , and a discharge port 103 is provided at the bottom of the recooler body 1 .

[0112] Specifically, the recooler body 1 is provided with a material fluidizing section 100, a gravity cooling section 200 and a discharging section from top to bottom, and the upper half of the fluidized drying section is also a feeding section. The feeding section usually has a shell with a rectangular cross-section that is consistent from top to bottom. The top of the feeding section shell is provided with one or more feeding ports 101 for adding powdered and granular materials to be processed; the top of the feeding section shell is provided with an exhaust port 102 for discharging gas; the internal space of the feeding section shell is used to accommodate materials, and the materials usually fill a part of the shell when in a working state. Under the action of fluidization, there is an obvious upper interface 8 of the material layer, and there is also a certain height of space above the material. Small particles entrained in the exhaust gas settle back to the material layer under the action of gravity at this height; the bottom of the feeding section shell is open, usually equal to the cross-section of the feeding section shell, and is used to connect with the feeding end of the material fluidizing section 100, or the feeding section itself is the upper half of the material fluidizing section 100, that is, there is a certain amount of residual space above the upper surface of the material layer of the material fluidizing section 100. A level meter is installed on the shell of the feeding section to measure the material level and transmit it electronically to the control system.

[0113] The recooler body 1 is provided with a material fluidizing section 100 and a gravity cooling section 200 from top to bottom.

[0114] The gravity cooling section 200 is provided with a heat exchanger assembly 3 connected to a heat exchange medium supply system.

[0115] The heat exchange medium supply system is used to provide refrigerant to the heat exchanger assembly 3 .

[0116] Specifically, the gas supply system includes a gas dehumidification device and / or a cooling device, and the heat exchange medium supply system includes a fluid cooling device (not shown in the drawings of this embodiment).

[0117] The gas dehumidification equipment is used to remove moisture from the gas to obtain dry gas, the gas cooling equipment is used to control the temperature of the dry gas, and the fluid cooling equipment is used to control the temperature of the refrigerant to prevent the material from absorbing moisture, agglomerating, and scarring.

[0118] like Figure 5 and Figure 6 As shown, the heat exchanger assembly 3 is a tubular heat exchanger or a plate heat exchanger. The heat exchange tubes in the tubular heat exchanger are arranged at intervals from each other, and the heat exchange plates in the plate heat exchanger are arranged at intervals from each other. The external space of the heat exchanger assembly 3 is the first material channel 1000, that is, the gaps between the heat exchange tubes in the tubular heat exchanger and the gaps between the heat exchange plates in the plate heat exchanger are the first material channel 1000, and the inside is the refrigerant fluid channel, which is separated by the heat exchange wall of the heat exchanger assembly 3, and heat is transferred through the wall.

[0119] like Figure 5 As shown, when the heat exchanger assembly 3 is a tubular heat exchanger, the heat exchanger assembly 3 includes a plurality of heat exchange tubes 901 arranged at intervals in the horizontal direction, which are arranged in the shell of the heavy cooler body 1 corresponding to each cooling section, and are used to cool the powder and granular materials. The heat exchange tube is a serpentine tube structure extending up and down, and each serpentine tube includes a horizontal tube part arranged at intervals from top to bottom and a bend part connecting adjacent horizontal tubes in sequence. The bottom and top horizontal tubes of the serpentine tube extend to the outside of the shell of the heavy cooler body 1 and are connected to the refrigerant inlet or outlet distribution main pipe; two adjacent serpentine heat exchange tubes are arranged in staggered rows up and down; the serpentine tube group formed by them is fixed by multiple partitions and a panel to form an independent heat exchanger assembly; the heat exchanger assembly is fixed on the shell of the heavy cooler body 1 by a fixing member (not shown in the figure), wherein the panel also serves as a fixing flange and is connected to the shell of the heavy cooler body 1 by fixing members such as sealing gaskets and bolts (not shown in the figure), and the heat exchanger assembly can be conveniently pulled out and loaded as a whole from the side of the shell of the heavy cooler body 1 during maintenance.

[0120] like Figure 6As shown, when the heat exchanger assembly 3 is a plate heat exchanger, the plate heat exchanger is provided with rows of point welding areas and linear welds arranged in an alternating manner up and down. A pillow-shaped expansion area is formed between the point welding areas as a channel for the heat exchange medium. The surrounding area of ​​each local welding area is raised to form a generally bowl-shaped pit, and the linear welds arranged in an alternating manner up and down form a serpentine path for the heat exchange medium to pass through. The pits in adjacent rows (or columns) are usually arranged in a staggered manner to increase the disturbance during the flow of internal fluid and the flow of external powder and granular materials, and the overall flow mode of the serpentine path avoids internal fluid short-circuiting, increases the process length, and increases the flow speed; the above measures can significantly improve the flow and heat transfer characteristics of fluids and materials.

[0121] When the heat exchanger assembly 3 is a plate heat exchanger, in order to improve the circulation of the gas inside the heat exchanger assembly 3, as Figure 7 As shown, gas exchange holes may be provided on the heat exchange plates 902 of the plate heat exchanger for gas to pass therethrough, thereby increasing the gas flow between different heat exchange plates to stabilize the gas flow state.

[0122] like Figure 5 , Figure 6 As shown, the refrigerant inlet distribution main pipe 400 and outlet distribution main pipe 500 are installed outside the shell of the heavy cooler body 1, and the first connecting pipe 600 for connecting the heat exchanger assembly 3 with the refrigerant distribution main pipe. The refrigerant enters each heat exchanger assembly 3 from the inlet distribution main pipe 400, and after indirect heat exchange with the material in the heat exchanger assembly 3, it is collected in the outlet distribution main pipe 500; the refrigerant can enter the heat exchanger assembly 3 from the lower distribution main pipe and then be discharged from the upper distribution main pipe, that is, the inlet distribution main pipe 400 is arranged below the outlet distribution main pipe 500, thereby forming a countercurrent heat exchange mode opposite to the material flow direction, obtaining a higher heat exchange temperature difference and faster cooling of the material, or it can enter the heat exchanger assembly 3 from the upper part and be discharged from the lower part, because the heat exchange temperature difference is low, the material cooling process can be carried out gently.

[0123] The gas distribution assembly includes a fluidizing air gas distribution assembly 2 disposed in the material fluidizing section 100, and the fluidizing air gas distribution assembly 2 is connected to the gas supply system.

[0124] like Figure 1 and Figure 4 As shown, the fluidizing air gas distribution assembly 2 includes a plurality of gas distribution pipes 300 installed inside the shell of the heavy cooler body 1. The gas distribution pipes 300 are located at the upper part of the heat exchanger assembly 3. The plurality of gas distribution pipes 300 are distributed on the same horizontal plane and are arranged in parallel with each other. The horizontal extension direction of the gas distribution pipes 300 is perpendicular to the horizontal extension direction of the heat exchange pipes 901 in the heat exchanger assembly 3 (e.g. Figure 4(a)), or the horizontal extension direction of the gas distribution pipe 300 is perpendicular to the horizontal extension direction of the heat exchange plate 902 in the heat exchanger assembly 3 (as shown in FIG. Figure 4 (b)), thereby ensuring that the first material channel 1000 and the second material channel 3000 are vertically connected to each other; Figure 8 , Fig. 9 and Fig.10 As shown, the lower half of each gas distribution pipe 300 is provided with one or more rows of air holes 4000 along the length direction, which are used to deliver the gas in the pipe to the material channel inside the box of the recooler body 1. The arrangement of the gas distribution pipe 300 and the opening of the holes on the pipe wall are used to ensure that the gas is evenly diffused over the entire shell cross-section of the recooler body 1 and passes upward through the material layer; a gas distribution main pipe 700 is installed on the outside of the shell of the recooler body 1, as well as a second connecting pipe 800 connecting the gas distribution pipe 300 with the gas distribution main pipe 700.

[0125] The fluidizing air gas distribution assembly 2 is used to introduce dry gas into the recooler body 1, so that the material in the material fluidizing section 100 is in a fluidized state, so that the material entering the material fluidizing section 100 is spread in the horizontal direction, and the bed material surface is tended to the same level, so as to ensure that the material particle size is evenly distributed and the moisture in the gap between the materials is fully replaced and discharged before entering the gravity cooling section 200. The present invention utilizes the liquid-like characteristics of fluidization to make the feed spread evenly and horizontally, and utilizes the high heat and mass transfer characteristics of fluidization to more fully replace the moisture and make the moisture of coarse and fine particles uniform, which are effects that cannot be achieved when the material is not in a fluidized state.

[0126] In this embodiment, the fluidizing air gas distribution assembly 2 is horizontally arranged in the material fluidizing section 100, and the material above the fluidizing air gas distribution assembly 2 is fluidized to form a fluidized bed layer of a certain height (for example: 500~1000mm). In order to achieve a better cooling effect, the fluidizing air gas distribution assembly 2 can also pass dry cold gas into the recooler body 1. In addition, in order to improve the deep drying effect, the fluidizing air gas distribution assembly 2 can also pass dry hot air higher than the material temperature or dry air with a temperature equivalent to the material temperature into the recooler body 1, and heat or keep the material warm while fluidizing the material.

[0127] In this embodiment, the cross-sectional areas of the upper and lower shells of the material fluidizing section 100 are uniform, and the fluidizing wind speed generated by the ventilation volume through the material fluidizing section is the average wind speed passing through the cross section calculated according to the horizontal net cross-sectional area of ​​the material fluidizing section 100. When the fluidizing wind gas distribution component 2 works independently, the fluidizing wind speed is 1 to 6 times the critical fluidizing speed calculated according to the average particle size of the material.

[0128] Preferably, the fluidization state of the material is bubbling fluidization.

[0129] like Figure 1 As shown, the gravity cooling section 200 is provided with multiple layers of heat exchanger components 3 from top to bottom, each layer of heat exchanger components 3 forms a cooling section. In this embodiment, three layers of cooling sections are provided.

[0130] like Figure 1 As shown, the gas distribution assembly also includes a replacement wind gas distribution assembly 4 arranged in the gravity cooling section 200, and the structure and arrangement of its gas distribution pipe 300 are the same as those of the fluidizing wind gas distribution assembly 2, and the replacement wind gas distribution assembly 4 is connected to the gas supply system.

[0131] The replacement air gas distribution assembly 4 is used to introduce dry gas into the recooler body 1 .

[0132] A layer of replacement wind gas distribution assembly 4 is arranged under each layer of heat exchanger assembly 3 .

[0133] In this embodiment, the cross-sectional areas of the upper and lower parts of the gravity cooling section 200 are uniform. When the replacement air distribution component 4 is partially or fully working, the ventilation volume or the sum of the ventilation volumes of the replacement air distribution component 4 generates an operating wind speed that is calculated according to the horizontal net cross-sectional area of ​​the gravity cooling section 200, and the operating wind speed is 0 to 0.5 times the critical fluidization speed calculated according to the average particle size of the material. Since the maximum ventilation volume of the fluidized air distribution component 2 is greater than the maximum ventilation volume of the replacement air distribution component 4, the opening rate of the side wall of the air distribution channel 2000 corresponding to the fluidized air distribution component 2 is greater than the opening rate of the side wall of the air distribution channel 2000 corresponding to the replacement air distribution component 4, that is, the total ventilation area of ​​the air distribution holes 4000 corresponding to the fluidized air distribution component 2 is greater than the total ventilation area of ​​the air distribution holes 4000 corresponding to the replacement air distribution component 4.

[0134] When the fluidizing air gas distribution component 2 and the replacement air gas distribution component 4 are working at the same time, the fluidizing air velocity generated when the ventilation volume of the fluidizing air gas distribution component 2 is calculated separately is not less than 0.7 times of the critical fluidizing velocity calculated according to the average particle size of the material, and the fluidizing air velocity generated by the sum of the ventilation volumes of the fluidizing air gas distribution component 2 and the replacement air gas distribution component 4 is not less than 1.2 times of the critical fluidizing velocity calculated according to the average particle size of the material. According to the dry gas replacement and material cooling effect of the material fluidization section 100 and / or the gravity cooling section 200, the replacement air gas distribution component 4 may not be opened or partially opened, and the air supply volume is adjustable.

[0135] The temperature of the refrigerant in each layer of the heat exchanger assembly 3 decreases from top to bottom, and the temperature difference between the refrigerant in the heat exchanger assembly 3 and the material outside the heat exchange wall is also reduced accordingly to reduce the probability of moisture absorption and agglomeration of the material. For materials with weak moisture absorption and adhesion characteristics, the temperature difference between the two can also be maintained to improve the cooling efficiency.

[0136] Each layer of heat exchanger assembly 3 adopts an independent heat exchange medium supply system, which can independently control the flow and / or temperature of the refrigerant in the connected heat exchanger assembly 3. Each independent heat exchange medium supply system includes a refrigerant heat exchanger, a pump, a circulating water tank and a corresponding pipeline system.

[0137] like Figure 1 As shown, the gravity flow indirect cooler also includes an auxiliary silo 5, the inlet of which is connected to the discharge port 103, and the outlet of which is connected to the feed port 101. In this embodiment, the auxiliary silo 5 is located above the main body 1 of the recooler, and the effective loading volume of the auxiliary silo 5 is approximately the loading volume of the main body 1 of the recooler when it is working normally; before the recooler is shut down, the cooled material is sent to the auxiliary silo 5 through the air bypass, and when it is started, it is quickly put into the main body 1 of the recooler to reach the preset material level above the heat exchanger assembly, thereby shortening the start-up process. In addition, the auxiliary silo 5 can be used as a temporary storage container during equipment failure inspection and maintenance to temporarily store the cooled material.

[0138] like Figure 1 As shown, the gravity flow indirect cooler further includes a material level meter 6 and a discharger 7 with adjustable flow rate.

[0139] The material level meter 6 is arranged on the top of the recooler body 1 and is used to measure the material level height of the material in the recooler body 1 .

[0140] The discharger 7 is connected to the discharge port 103 and is used to adjust the discharge speed of the material to control the material level height in the recooler body 1 .

[0141] In this embodiment, pneumatic conveying equipment is used for feeding, that is, the outlet of the discharger 7 is connected to the feeding equipment of the pneumatic conveying equipment, the air inlet of the pneumatic conveying equipment adopts the same parameters as the dry cold gas, and a return bypass is set on the pneumatic conveying main pipeline to feed the auxiliary silo 5.

[0142] The discharger 7 can be any one of various forms such as a rotary air lock discharge valve, a vibrating discharger, a belt discharger, a single-axis or multi-axis spiral discharger, etc. The discharger 7 has a driving device and a discharge speed controller. The discharge speed controller receives the electrical signal of the level meter 6 installed on the top of the recooler body 1, and then controls the discharger 7 to adjust the discharge flow rate to ensure that the upper surface 8 of the material layer is higher than the upper surface of the fluidizing air gas distribution component 2 by a certain height, thereby forming a fluidized material layer of a certain height on its upper part, ensuring that the feed is evenly distributed while achieving sufficient replacement of the humid and hot gas carried by the material to be cooled, and ensuring that the material will not absorb moisture and form scars on the wall of the heat exchanger component 3.

[0143] The discharge section is a discharge cone hopper that is larger at the top and smaller at the bottom, and is used to receive powdery or granular materials coming down from the gravity cooling section 200; the upper part of the cone hopper has the same cross-section as the shell of the gravity cooling section 200 and is connected to it, and the cone hopper gradually shrinks from top to bottom to transition to the same cross-section as the discharge port 103 and is connected to it.

[0144] One or more auxiliary discharging devices such as vibration and knocking are installed on the wall of the discharging section to assist the flow of materials in the cone bucket through mechanical vibration or knocking; or one or more auxiliary discharging devices that use compressed gas to impact the material are installed to loosen the material by instantly releasing the compressed gas. The function of the auxiliary discharging device is to prevent the material from being locally compacted or "bridged" and other flow obstructions, and ensure that the material is discharged smoothly in an overall flow manner.

[0145] The gravity flow indirect cooler also includes support, lifting lugs, flanges, inspection doors, manholes, hand holes, sight glasses, instrument mounting seats (holes) and other auxiliary components and structures for supporting, fixing, hoisting, connecting, inspecting, observing, and testing. These are required for conventional engineering or equipment design and will not be described in detail here.

[0146] A cooling method, using the above-mentioned gravity flow indirect cooler, comprises the following steps:

[0147] S0. Before feeding, dry gas is introduced into the main body of the recooler using a gas distribution assembly or a vent pipe attached to the lower part of the main body to replace the gas in its internal space so that its internal environment is in a dry gas atmosphere when it is unloaded.

[0148] S1. Use materials to completely bury the heat exchanger assembly 3 in the recooler body 1.

[0149] S2. Use the gas distribution component to introduce dry gas into the recooler body 1, so that the material in the material fluidization section 100 is in a fluidized state, ensuring that the material is evenly distributed in the cross-section of the recooler body 1, and enters the gravity cooling section 200 in this evenly distributed state. At the same time, utilize fluidization to fully replace the humid gas between the material particles with dry gas, and bring the moisture in the tidal gas and the moisture precipitated in the material out of the recooler body 1.

[0150] S3. Use the heat exchanger assembly 3 of the gravity cooling section 200 to cool the material, and control the refrigerant inlet temperature of each heat exchanger assembly 3 to be higher than the moisture absorption, agglomeration or scarring temperature of the material on the material side of the corresponding heat exchanger assembly 3.

[0151] In step S1, the method of using materials to completely bury the heat exchanger assembly 3 in the recooler body 1 is:

[0152] S11, a gas distribution assembly is arranged at the upper end of the interior of the recooler body 1.

[0153] Before cooling the material to be cooled, the cooled material is quickly added to the recooler body 1 to a preset height through the auxiliary silo 5 or through the auxiliary silo 5, manual feeding or other dry cooling system continuous transfer; the preset height is higher than the gas distribution component.

[0154] S12. Dry gas is introduced through the gas distribution component to put the material above the gas distribution component into a fluidized state.

[0155] S13 . Next, the material to be cooled is continuously fed into the recooler body 1 from the feed inlet 101 at the top of the recooler body 1 .

[0156] Alternatively, in step S1, the method of using materials to completely bury the heat exchanger assembly 3 in the recooler body 1 is:

[0157] S11. Multiple layers of gas distribution components are sequentially arranged from top to bottom inside the recooler body 1; and materials to be cooled are continuously fed into the recooler body 1 from the feed inlet 101 at the top of the recooler body 1.

[0158] S12. While the material is being added, when the material level reaches the lowest gas distribution component, the lowest gas distribution component is started and dry cold gas is introduced to fluidize the material above the gas distribution component.

[0159] S13. When the material level reaches the upper gas distribution component, close or turn down the lower gas distribution component, and open the upper gas distribution component to continue to introduce dry cold gas, and at the same time, introduce refrigerant into the heat exchanger component 3 between the lower gas distribution component and the upper gas distribution component to cool the material.

[0160] The above operations are performed upward in sequence until the material level reaches a preset height, and finally a material fluidization section 100 and a gravity cooling section 200 arranged up and down are formed.

[0161] The present invention has the following beneficial effects when processing powdery and granular products, especially when processing products that are easy to absorb moisture and agglomerate produced by fermentation plants:

[0162] 1. Effectively solve the problem of material agglomeration and scarring on the surface of heat exchange plates (or tubes), especially the first and second heat exchange groups in contact with the feed, so as to ensure the long-term stable operation of the equipment without blockage, scarring, unchanged heat exchange efficiency, and no agglomeration of the material itself during the cooling process.

[0163] 2. The entire cooling process is uniform and consistent, and the cooling efficiency is further improved, so that products with lower temperature, more uniform temperature and moisture content, and no moisture absorption can be obtained, thereby effectively solving the problem of product hardening during storage and transportation.

[0164] 3. The functions of deep drying, moisture homogenization and deep cooling of materials are completed in the same equipment, which expands the performance of the equipment.

[0165] 4. Reduce the height-to-diameter ratio of the equipment (the height-to-length ratio or height-to-width ratio for rectangular equipment), and ensure uniform and consistent deep cooling effect at a lower height-to-diameter ratio, or use a larger cross-section at the same height and ensure uniform cooling effect, thereby increasing equipment capacity. Reducing the height of the equipment also reduces equipment and plant investment.

[0166] Example 2

[0167] like Figure 2 As shown, the difference from Example 1 is that the material fluidizing section 100 is provided with a heat exchanger assembly 3 connected to a heat exchange medium supply system, and the heat exchange medium supply system is used to provide refrigerant to the heat exchanger assembly 3 in the material fluidizing section 100. Specifically, in this embodiment, three layers of heat exchanger assemblies are provided, the material fluidizing section 100 is provided with a layer of heat exchanger assembly 3, and a layer of fluidizing wind gas distribution assembly 2 is provided below the heat exchanger assembly 3 in the material fluidizing section 100; the gravity cooling section 200 is provided with two layers of heat exchanger assemblies 3 from top to bottom, and the corresponding replacement wind gas distribution assembly 4 is provided with two layers; the fluidizing wind gas distribution assembly 2 and the replacement wind gas distribution assembly 4 are both connected to the gas supply system.

[0168] The material discharging speed is controlled by the discharging device 7 to ensure that the upper surface of the material layer is higher than the uppermost heat exchanger assembly 3 by a certain height, thereby ensuring that the heat exchanger assembly 3 is completely buried in the material.

[0169] In this embodiment, dry gas is introduced into the fluidizing air gas distribution assembly 2 at a flow rate that causes the material on the upper portion to be in a fluidized state. This eliminates feed cone and segregation phenomena and replaces the wet feed gas. At the same time, the high heat and mass transfer rates in the fluidized state are utilized to deeply dry and efficiently cool the material, further reducing the moisture content of the feed and eliminating the difference in feed temperature and moisture content.

[0170] The upper surface 8 of the fluidized material layer only needs to be located above the heat exchanger assembly (for example, 0-200 mm), which ensures that the heat exchanger is fully filled with material to exchange heat with the material and reduces the energy consumption required to overcome the resistance of the material layer.

[0171] In this example, the implementation effect of an industrial device for cooling a 70% lysine fluidized bed granulation product in a fermentation plant is given. The material bulk density is 580 kg / m 3The particle size range is 0.6-1.7mm, and the average particle size is 1.1mm. The critical fluidization velocity calculated based on the average particle size is ~0.21m / s (varies with parameters such as air temperature and pressure). The cooling parameters and effects are as follows:

[0172] 1. The fluidizing air or displacement air provided by the gas distribution component is dry cold air after dehumidification and cooling of the ambient air, with a wind temperature of 20℃~25℃ and a dew point temperature ≤0℃. By controlling the dew point temperature of the incoming gas, the dew point temperature of the gas environment on the material side of the recooler body 1 is reduced, and the use of lower temperature refrigerant is achieved without causing scarring on the wall of the heat exchanger component 3, which effectively improves the cooling efficiency.

[0173] 2. There are three cooling sections from top to bottom, namely high-temperature cooling section, medium-temperature cooling section and low-temperature cooling section. The high-temperature cooling section adopts cooling water and fluidizing air (a small amount of replacement air is added when the replacement air is turned on) combined cooling. The cooling water inlet temperature of the heat exchanger component 3 is controlled at 30-35°C, which reduces the heat transfer temperature difference between the material and the refrigerant while avoiding excessive relative humidity of the air, thereby causing the material to form scars on the wall of the heat exchanger component 3 or the particles to absorb moisture or condense on the surface to form a hardening; when all the replacement air gas components are in the closed state, the fluidizing air speed is 0.3-0.6m / s, and the fluidization number is between 1.4 and 2.9; when the replacement air gas components are all in the closed state, the fluidizing air speed is 0.3-0.6m / s, and the fluidization number is between 1.4 and 2.9; when the replacement air gas When the component is turned on, the total air volume of fluidizing air and replacement air remains unchanged, that is, the fluidization number generated by the total air volume is still between 1.4 and 2.9. At this time, the fluidization wind speed calculated according to the ventilation volume of the fluidizing air gas component is reduced to 0.2m / s, and the corresponding fluidization number is 0.95, thereby ensuring that the materials under both working conditions are evenly and fully operated in a bubbling fluidized state, bringing out the water vapor contained in the air in the material gap, and avoiding local material flow blockage; when the fluidization number is between 1.4 and 2.9, the heat transfer efficiency between the fluidized material and the heat exchange wall is also high, and the scouring of the heat exchange wall by the material in the fluidization also prevents or reduces the wall scarring.

[0174] The cooling water inlet temperature of the heat exchanger assembly 3 in the medium-temperature cooling section is controlled at 22-25°C to obtain a relatively ideal cooling effect while avoiding scarring; at the same time, replacement air is introduced, and the operating wind speed is 0.05-0.1m / s, so that the material is in a fluidization number between 0.24 and 0.48, and the water vapor in the gap between the materials is taken out to maintain a dry air environment, while ensuring that the material is in an aerated state to improve the fluidity of the material. Because the fluidity of 70% lysine particles is good, and the moisture in the material has been fully replaced in the high-temperature cooling section, the replacement air can also be not introduced in the dry season to save air volume.

[0175] The cooling water inlet temperature of the low-temperature cooling section heat exchanger component 3 is controlled at 8-20°C, and a deep cooling effect of 25-30°C or below can be obtained. At this time, the material has been cooled to a temperature close to the discharge temperature, the heat transfer temperature difference between the material and the refrigerant is low, the material is in a fully dry and cold environment, and there is basically no moisture or condensation on the material. Generally, there is no need to ventilate the replacement air. The replacement air can also be turned on according to the material and weather conditions. If the replacement air is turned on, the operating wind speed is similar to or lower than that of the medium-temperature cooling section. However, when the two replacement air gas components are turned on, the operating wind speed generated by the sum of the ventilation volume is not easy to exceed the fluidization number 0.5.

[0176] The effect is as follows:

[0177] (1) In actual application, during the hot and humid weather period in summer, the gravity flow indirect cooler of this embodiment can operate continuously for more than 60 days without the material agglomerating or scarring on the heat exchanger; the cooling effect is stable and continuous, and when the feed temperature is 75℃-80℃, the material can be cooled to about 25℃; the temperature difference of the material after cooling is very small.

[0178] The above cooling effect, together with strict moisture control measures in the upstream drying process and downstream transportation and packaging processes, basically eliminates the compaction phenomenon of 70% lysine granular packaging products during long-term storage.

[0179] (2) Improved product quality. The slow and controllable flow of material particles effectively prevents wear and tear of the product, and no fine powder is generated during the cooling process. In the indirect heat transfer method, the material is basically not in contact with the air, which avoids the increase of the moisture content of the product during the cooling process; the deep dehumidified dry air can even make the moisture distribution of the material more uniform and further reduce the moisture content.

[0180] (3) During the cooling process, the temperature is less than 1500m 3 / h of tail gas emissions, compared with the fluidized bed cooling process 15000m 3 / h of tail gas emissions, reducing more than 90%, achieving near-zero emissions; the tail gas is merged into a large amount of dry tail gas for dust removal and deodorization, without the need for separate equipment.

[0181] (4) High energy efficiency. Due to the use of cooling water for indirect heat exchange, the dehumidification and cooling steps of air cooling are omitted. In summer, the consumption of ice water is reduced from 120m 3 / h reduced to 25m 3 / h, saving about 80%.

[0182] By utilizing the gravity flow of the material itself, a large amount of fluidizing air pressurization and negative pressure suction links as well as equipment operation links are eliminated. The installed power of the entire system is reduced from 125kw to 18kw, and power consumption is saved by about 85%.

[0183] (5) The fluidized bed and its associated bag filter, induced draft fan and other ancillary equipment occupy an area of ​​200m 2 The heavy cooler omits large equipment such as bag dust collector and induced draft fan, and has fewer ancillary equipment, covering an area of ​​only 60m 2 Within 10 days, 70% can be saved, thus saving equipment and plant investment.

[0184] Example 3

[0185] like Figure 3 As shown, the difference from Example 1 is that the material fluidizing section 100 is provided with a layer of heat exchanger assembly 3, and a layer of fluidizing wind gas distribution assembly 2 is respectively provided on the upper and lower sides of the heat exchanger assembly 3 in the material fluidizing section 100.

[0186] In this embodiment, two sets of fluidizing air gas distribution components 2 can be used to perform deep drying and cooling operations on the fed materials at the same time, thereby further improving the quality of the product. The description is as follows:

[0187] By introducing dry gas into the fluidized air gas distribution component 2 on the upper side, the flow rate of the gas introduced, or the ventilation volume from the fluidized air gas distribution component on the lower side, the upper limit of the fluidization number of the upper fluidized material layer can even be operated between 3 and 6, and the material layer is in a more intense boiling state. While completely eliminating the feed cone and segregation phenomenon and fully replacing the humid gas in the feed, the high heat and mass transfer rate of the fluidized material layer is used to deeply dry the material to further reduce the moisture content of the feed and eliminate the difference in moisture content of the feed material at various locations. In order to further improve the effect of deep drying and eliminate the moisture difference of particles of different particle sizes, the temperature of the dry gas can be appropriately increased until it is close to the feed temperature, so as to reduce the relative moisture content of the gas in the gap between the particles and increase the mass transfer and heat transfer driving force for the moisture in the material to diffuse into the gas.

[0188] For materials with strong moisture absorption and agglomeration characteristics, since the material temperature is still relatively high when the material passes downward through the fluidizing air gas component on the upper side, the flow rate of gas introduced into the fluidizing air gas distribution component 2 below (including this part of air volume when the displacement air gas component is working) keeps the fluidization number above 1, so that the material layer in the area where the heat exchanger component 3 is located is also evenly and fully operated in a bubbling fluidization state, avoiding local material flow blockage; the heat transfer efficiency of the cooling process between the material in fluidization and the heat exchange wall is also relatively high, and the flushing of the heat exchange wall by the material in fluidization also prevents or reduces the scarring of the high-temperature section material on the wall.

[0189] When processing materials with weak moisture absorption and agglomeration characteristics or producing in dry and cold seasons, a small amount of dry and cold gas is introduced into the lower fluidized air gas distribution component 2 in cooperation with the upper fluidized air gas distribution component 2 to displace the hot gas in the gaps between the material particles that have moved down to the heat exchanger area, i.e., the heat exchanger component 3, and discharge it upward to the fluidized bed layer. Since the moisture in the material has been further removed and homogenized in the material layer above the upper fluidized air gas distribution component 2, the gas in the gaps between the particles still maintains a very low moisture content, and the possibility of material agglomeration or scarring can be avoided by introducing a small amount of dry and cold gas; alternatively, the lower fluidized air gas distribution component 2 can be unventilated, and only the heat exchanger component 3 is used to cool the material. In both cases, the lower fluidized air gas component is equivalent to the replacement air gas distribution component in Example 1, and the selection of its operating wind speed is also similar, thereby saving the power consumption required for gas pressurization.

Claims

1. A gravity flow indirect cooler, characterized in that: It comprises a recooler body (1), a gas distribution component, a heat exchanger component (3), a gas supply system and a heat exchange medium supply system; The heat exchanger assembly (3) is a plate heat exchanger or a tube heat exchanger, and a first material channel (1000) penetrating vertically is provided between the heat exchange plates or between the heat exchange tubes of the heat exchanger assembly (3); The gas distribution assembly comprises an air distribution channel (2000) distributed along the cross section of the recooler body (1); second material channels (3000) are arranged on the outside of the air distribution channel (2000) and are distributed along the cross section of the recooler body (1) at intervals from each other; and air distribution holes (4000) are arranged on the side wall of the air distribution channel (2000) and are communicated with the inner cavity of the recooler body (1); The recooler body (1) is a vertical shell, the top of the recooler body (1) is provided with a feed inlet (101) and an exhaust port (102), and the bottom of the recooler body (1) is provided with a discharge port (103); The recooler body (1) is provided with a material fluidizing section (100) and a gravity cooling section (200) from top to bottom; The gravity cooling section (200) is provided with a heat exchanger assembly (3) connected to a heat exchange medium supply system; The heat exchange medium supply system is used to provide refrigerant to the heat exchanger assembly (3); The gas distribution component comprises a fluidizing air gas distribution component (2) arranged in the material fluidizing section (100), the fluidizing air gas distribution component (2) being connected to the gas supply system, the gas distribution component being located at the upper end of the recooler body (1), the fluidizing air gas distribution component (2) being used to introduce dry gas into the recooler body (1), so that the material in the material fluidizing section (100) is in a fluidized state, so that the material entering the material fluidizing section (100) is spread out in a horizontal direction, so as to ensure that the material is evenly distributed, the moisture in the gaps between the materials is fully replaced and discharged, and then enters the gravity cooling section (200), thereby ensuring that the material moves downward evenly as a whole, so that when the material passes through the gravity cooling section, it can be evenly cooled by the heat exchanger component, so that the material is in a dry gas environment, effectively avoiding scarring on the wall of the heat exchanger component and material agglomeration, and realizing uniform moisture content of the material at various locations within the same cross section of the recooler body; The gas distribution assembly further comprises a replacement wind gas distribution assembly (4) arranged in the gravity cooling section (200).

2. The gravity flow indirect cooler according to claim 1, characterized in that: When the fluidizing air gas distribution component (2) works independently, the fluidizing air velocity generated by the ventilation volume of the fluidizing air gas distribution component (2) is 1 to 6 times the critical fluidizing velocity calculated based on the average particle size of the material.

3. The gravity flow indirect cooler according to claim 1, characterized in that: The gravity cooling section (200) is provided with multiple layers of heat exchanger components (3) from top to bottom, each layer of heat exchanger components (3) forms a cooling section, and the temperature of the refrigerant in each layer of heat exchanger components (3) decreases sequentially from top to bottom.

4. The gravity flow indirect cooler according to claim 3, characterized in that: Each layer of heat exchanger assembly (3) adopts an independent heat exchange medium supply system, and the heat exchange medium supply system can independently control the flow rate and / or temperature of the refrigerant in the heat exchanger assembly (3) to which it is connected.

5. The gravity flow indirect cooler according to claim 3, characterized in that: The replacement air gas distribution component (4) is connected to the air supply system; The replacement air gas distribution assembly (4) is used to introduce dry gas into the recooler body (1); A layer of replacement air gas distribution component (4) is provided below each layer of heat exchanger components (3).

6. The gravity flow indirect cooler according to claim 5, characterized in that: When the replacement air distribution component (4) is partially or fully operational, the ventilation volume or the sum of the ventilation volumes of the replacement air distribution component (4) generates an operating The wind speed is 0~0.5 times the critical fluidization velocity calculated based on the average particle size of the material; When the fluidizing air gas distribution component (2) and the replacement air gas distribution component (4) are working simultaneously, the fluidizing air velocity generated when the ventilation volume of the fluidizing air gas distribution component (2) is calculated alone is not less than 0.7 times the critical fluidizing velocity calculated according to the average particle size of the material, and the fluidizing air velocity generated by the sum of the ventilation volumes of the fluidizing air gas distribution component (2) and the replacement air gas distribution component (4) is not less than 1.2 times the critical fluidizing velocity calculated according to the average particle size of the material.

7. The gravity flow indirect cooler according to claim 1, characterized in that: The material fluidizing section (100) is provided with a heat exchanger assembly (3) connected to a heat exchange medium supply system; The heat exchange medium supply system is used to provide cooling medium to the heat exchanger assembly (3) in the material fluidizing section (100).

8. The gravity flow indirect cooler according to any one of claims 1 to 7, characterized in that: It also comprises an auxiliary silo (5), the inlet of the auxiliary silo (5) being connected to the discharge port (103), and the outlet of the auxiliary silo (5) being connected to the feed port (101).

9. The gravity flow indirect cooler according to any one of claims 1 to 7, characterized in that: It also includes a material level meter (6) and a discharger (7) with adjustable flow rate; The material level meter (6) is arranged on the top of the recooler body (1) and is used to measure the material level height of the material in the recooler body (1); The discharger (7) is connected to the discharge port (103) and is used to adjust the discharge speed of the material so as to control the material level height in the recooler body (1).

10. The gravity flow indirect cooler according to claim 1 or 7, characterized in that: The gas supply system includes a gas dehumidification device and / or a gas cooling device, and the heat exchange medium supply system includes a fluid cooling device; The gas dehumidification equipment is used to remove moisture from the gas to obtain dry gas, the gas cooling equipment is used to control the temperature of the dry gas, and the fluid cooling equipment is used to control the temperature of the refrigerant to prevent the material from absorbing moisture, agglomerating, or scarring on the wall of the heat exchanger.

11. The gravity flow indirect cooler according to claim 1 or 7, characterized in that: The heat exchanger assembly (3) comprises a plurality of heat exchange tubes arranged at intervals in a horizontal direction, wherein the heat exchange tubes are serpentine tubes extending up and down; Two adjacent serpentine heat exchange tubes are arranged in an up-and-down staggered manner.

12. The gravity flow indirect cooler according to any one of claims 1 to 7, characterized in that: The gas distribution assembly comprises a plurality of gas distribution pipes (300) arranged horizontally and spaced apart from each other, and the air distribution holes (4000) are arranged below the gas distribution pipes (300); The air distribution holes (4000) are arranged in rows at intervals along the axial direction of the gas distribution pipe (300), and at least one row of air distribution holes (4000) is arranged below each gas distribution pipe (300); The gas distribution pipe (300) is a straight pipe, and the gas distribution pipe (300) and the heat exchange pipe in the heat exchanger assembly (3) are perpendicular to each other, or the gas distribution pipe (300) and the heat exchange plate in the heat exchanger assembly (3) are perpendicular to each other.

13. A cooling method, using the gravity flow indirect cooler according to any one of claims 1 to 12, characterized in that: The following steps are involved: S1. Using materials to completely cover the heat exchanger assembly (3) in the recooler body (1); S2. Dry gas is introduced into the recooler body (1) by using a gas distribution component to fluidize the material in the material fluidization section (100), thereby ensuring that the material is evenly distributed in the cross section of the recooler body (1), and enters the gravity cooling section (200) in this evenly distributed state. At the same time, the wet gas between the material particles is fully replaced with dry gas by fluidization, and the moisture in the humid gas and the moisture precipitated in the material are taken out of the recooler body (1); S3. Cooling the material using the heat exchanger assembly (3) of the gravity cooling section (200), and controlling the refrigerant inlet temperature of each heat exchanger assembly (3) to be higher than the moisture absorption, agglomeration or scarring temperature of the material on the material side of the corresponding heat exchanger assembly (3).

14. The cooling method according to claim 13, characterized in that: In step S1, the method of using materials to completely bury the heat exchanger assembly (3) in the recooler body (1) is: S11, disposing a gas distribution assembly at the upper end of the recooler body (1); Before cooling the material to be cooled, the cooled material is quickly added into the recooler body (1) to a preset height; S12, using the gas distribution component to introduce dry gas, so that the material above the gas distribution component is in a fluidized state; S13. Next, the material to be cooled is continuously fed into the recooler body (1) from the feed inlet (101) at the top of the recooler body (1).

15. The cooling method according to claim 13, characterized in that: In step S1, the method of using materials to completely bury the heat exchanger assembly (3) in the recooler body (1) is: S11, arranging multiple layers of gas distribution components in order from top to bottom inside the recooler body (1), and continuously feeding the material to be cooled into the recooler body (1); S12, while feeding the material, when the material level rises to the lowest gas distribution component, start the lowest gas distribution component and introduce dry cold gas to make the material above the gas distribution component enter a fluidized state; S13. When the material level reaches the upper gas distribution component, the lower gas distribution component is closed or turned down, and the upper gas distribution component is opened to continue to introduce dry gas, and refrigerant is introduced into the heat exchanger component (3) between the lower gas distribution component and the upper gas distribution component to cool the material; The above operations are performed in sequence upwards until the material level reaches a preset height, and finally a material fluidization section (100) and a gravity cooling section (200) arranged vertically are formed.

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