Spray granulation drying system and drying method

Abstract

The present invention discloses a spray granulation drying system and a drying method. The system includes a granulation drying device and a hot air furnace; the carrier gas outlet of the granulation drying device is connected to a cyclone dust removal device, a carrier gas condensation device and a carrier gas circulation fan through a pipeline; the outlet pipeline of the carrier gas circulation fan is divided into three routes: the first outlet pipeline is connected to the first carrier gas inlet; the third outlet pipeline; the hot air furnace is provided with a first smoke inlet, a second smoke inlet and a smoke outlet; the third outlet pipeline of the carrier gas circulation fan is connected to the first smoke inlet through a carrier gas bypass fan; the smoke outlet is connected to the hot fluid channel of the heat exchanger and the smoke induced draft fan in turn through a pipeline; the outlet pipeline of the smoke induced draft fan is divided into three routes: the fourth outlet pipeline is connected to the second carrier gas inlet; the sixth outlet pipeline is connected to the second smoke inlet. The system of the present application can not only efficiently dry wet materials, but also eliminate the risk of explosion, and make adjustments when the oxygen concentration of the carrier gas increases, so as to ensure safe production.

Description

Technical Field

[0001] The invention relates to a spray granulation drying system and a drying method. Background Art

[0002] The heat exchange forms of material drying can be divided into partition heat exchange and direct contact heat exchange. The advantage of partition heat exchange is that there is no direct contact between the material and the drying medium. The drying process will neither introduce impurities nor have the risk of combustion or explosion of combustibles; but the heat exchange efficiency is low, the equipment size is large, and the manufacturing cost is high. The direct contact heat exchange method is to directly mix and fully contact the cold phase logistics (wet material) and the hot phase logistics (drying medium), which greatly improves the heat exchange efficiency; but if the wet material is easy to release combustible gas when heated and dried, or the material itself is flammable, then when a certain amount of oxygen is mixed into the drying medium, it is easy to cause an explosion accident, threatening the safety of personnel and equipment.

[0003] Chinese patent document CN1508501A discloses a nitrogen-circulating engineering plastic gas flow and fluidized bed drying method: nitrogen is used as an internal circulation drying carrier gas to reduce the oxygen concentration in the internal circulation carrier gas, thereby solving the risk of dust explosion and monomer combustion when the material is heated under open circuit drying conditions; however, when the oxygen concentration exceeds the standard, a large amount of nitrogen is injected into the system for dilution, introducing a cold source, which has an adverse effect on the drying of the material; in addition, the demand for nitrogen is large, and the cost of nitrogen production cannot be ignored.

[0004] Chinese patent document CN101813316B discloses a municipal sludge drying and incineration system and its treatment process: the high-temperature flue gas generated by incinerating a part of the dried sludge is used as the carrier gas and heat source for sludge drying, and the heat required for drying is also provided entirely by the heat released by combustion; the dried sludge is burned in the incinerator as a two-phase reaction of gas (air diluted by the dried flue gas) and solid (dried sludge). To ensure better burnout and heat release effects, the air coefficient in the incinerator is relatively high, resulting in a relatively high oxygen concentration in the high-temperature flue gas. After the high-temperature flue gas with a relatively high oxygen concentration enters the dryer, material combustion or even dust explosion is likely to occur.

[0005] Chinese patent document CN208426828U discloses a near-zero emission system for the tail gas of MSG spray granulation: the tail gas of spray granulation (the temperature is 80°C, which is relatively low and can reduce the risk of dust explosion) is used as the internal circulation drying carrier gas. The tail gas of spray granulation is the non-condensable gas released during the material drying process, but in the initial operation state of the system, the internal circulation carrier gas is air. As the material is dried and the non-condensable gas is continuously released, the air in the internal circulation carrier gas is gradually replaced by the non-condensable gas; but in this process, there must be a situation where the flammable non-condensable gas and air are mixed within the explosion limit range. After being heated by high and medium temperature heat exchangers, explosion risk is very likely to occur.

[0006] Therefore, based on the existing technology, in order to reduce the risk of combustion and explosion, the risk of combustion and explosion is generally reduced by reducing the oxygen concentration or lowering the temperature of the carrier gas in the system, using flue gas with a lower oxygen concentration or directly using nitrogen as the carrier gas; however, the following technical problems still exist: 1) There is a gradual transition state between the internal circulation carrier gas and the oxygen-containing air, which poses a risk of explosion; 2) When nitrogen is used as the internal circulation carrier gas, the cost of nitrogen production is relatively high. Summary of the invention

[0007] The technical problem to be solved by the present invention is to overcome the defects of the prior art spray granulation system in which there is a gradual transition between the internal circulating carrier gas and the oxygen-containing air during the drying process, which poses a safety risk and the high cost of nitrogen, and to provide a spray granulation drying system and a drying method.

[0008] The present invention solves the above technical problems through the following solutions:

[0009] The spray granulation drying system of the present invention comprises a granulation drying device and a hot air furnace;

[0010] The granulation drying device is provided with a feed inlet, a first carrier gas inlet, a second carrier gas inlet and a carrier gas outlet;

[0011] The carrier gas outlet of the granulation drying device is connected to the cyclone dust removal device, the carrier gas condensation device and the carrier gas circulation fan in sequence through pipelines; wherein the outlet pipeline of the carrier gas circulation fan is divided into three routes: a first outlet pipeline is connected to the first carrier gas inlet; a second outlet pipeline is used to communicate with the atmosphere; and a third outlet pipeline;

[0012] The hot blast stove is provided with a first smoke inlet, a second smoke inlet and a smoke outlet;

[0013] The third outlet pipe of the carrier gas circulation fan is connected to the first smoke inlet through the carrier gas bypass fan; the smoke outlet is connected to the hot fluid channel of the heat exchanger and the smoke induced draft fan in sequence through the pipe; the outlet pipe of the smoke induced draft fan is divided into three routes: the fourth outlet pipe is connected to the second carrier gas inlet; the fifth outlet pipe is used to communicate with the atmosphere; and the sixth outlet pipe is connected to the second smoke inlet;

[0014] The feed inlet of the granulation drying device, the first outlet pipe, the second outlet pipe, the fourth outlet pipe and the fifth outlet pipe are respectively provided with a first on-off component, a second on-off component, a third on-off component, a fourth on-off component and a fifth on-off component.

[0015] In the present invention, the granulation and drying device is generally provided with a discharge port.

[0016] In the present invention, the granulation drying device is preferably provided with a return port for conveying the material returned for drying.

[0017] The cyclone dust removal device is generally provided with a discharge port, and the discharge port of the cyclone dust removal device is connected with the return port of the granulation and drying device.

[0018] In the present invention, preferably, a first oxygen measuring device is provided on the outlet pipe of the carrier gas circulation fan. The first oxygen measuring device is used to monitor the oxygen concentration of the carrier gas in the spray granulation drying system.

[0019] Among them, more preferably, the spray granulation drying system also includes an oxygen concentration control module, which is used to implement the following control steps: determine whether the carrier gas oxygen concentration monitored by the first oxygen measuring device is higher than 1% Vol., and when it is determined to be yes, execute the step of "opening the third on-off component and the fourth on-off component, and closing the second on-off component and the fifth on-off component"; and when it is determined to be no, execute the step of "closing the third on-off component and the fourth on-off component, and opening the second on-off component and the fifth on-off component".

[0020] In the present invention, preferably, the first outlet pipe is connected to the first carrier gas inlet through the cold fluid channel of the heat exchanger.

[0021] In the present invention, a sixth on-off component is generally provided on the third outlet pipe.

[0022] In the present invention, a seventh on-off component is generally provided between the carrier gas condensing device and the carrier gas circulation fan.

[0023] In the present invention, preferably, the fifth outlet pipe is connected to the atmosphere through a flue gas purification device.

[0024] In the present invention, the sixth outlet pipe is generally provided with an eighth on-off component.

[0025] In the present invention, preferably, a second oxygen measuring device is provided on the pipe of the flue gas outlet. The second oxygen measuring device provided in the present application is to monitor the oxygen concentration of the flue gas output from the hot blast stove.

[0026] In the present invention, the on-off component may be a conventional shut-off valve in the art, preferably a regulating valve.

[0027] In the present invention, those skilled in the art may add a temperature measuring device and / or a pressure measuring device to the pipeline according to actual needs to ensure safe operation of the system.

[0028] The present invention also provides a spray granulation drying method, which adopts the spray granulation drying system to perform drying, and comprises the following steps: adding the material to be dried into the granulation drying device and drying.

[0029] In the present invention, preferably, before the material to be dried is added into the granulation drying device, the drying method further comprises the following steps:

[0030] Step S1: closing the first on-off component, the second on-off component and the fifth on-off component, opening the third on-off component and the fourth on-off component, and starting the hot air furnace;

[0031] Step S2: When the spray granulation drying system runs to a carrier gas oxygen concentration of 1% Vol. or less, the third on-off component and the fourth on-off component are closed, and the first on-off component, the second on-off component and the fifth on-off component are opened.

[0032] According to conventional operations in the art, those skilled in the art generally know that the fifth on-off component is turned on first, and then the first on-off component and the second on-off component are turned on.

[0033] Among them, generally, when the spray granulation drying system also includes a sixth on-off component, a seventh on-off component and an eighth on-off component, according to conventional operations in the field, those skilled in the art know that in step S1, it is also necessary to open the seventh on-off component and the eighth on-off component, and close the sixth on-off component.

[0034] Preferably, when a first oxygen measuring device is provided on the outlet pipe of the carrier gas circulation blower, in step S2, the oxygen concentration of the carrier gas is monitored by the first oxygen measuring device.

[0035] Preferably, when the spray granulation drying system includes a first oxygen measuring device and an oxygen concentration control module, the control steps of the oxygen concentration control module include:

[0036] It is determined whether the oxygen concentration of the carrier gas monitored by the first oxygen measuring device is higher than 1% Vol. If it is determined to be yes, the step of "opening the third on-off component and the fourth on-off component, and closing the second on-off component and the fifth on-off component" is performed; and if it is determined to be no, the step of "closing the third on-off component and the fourth on-off component, and opening the second on-off component and the fifth on-off component" is performed. Among them, those skilled in the art know that "no" means determining whether the oxygen concentration of the carrier gas monitored by the first oxygen measuring device is below 1% Vol.

[0037] Generally, when a second oxygen measuring device is provided on the flue gas outlet pipe, those skilled in the art know that the flue gas distribution of the hot blast furnace needs to be adjusted to ensure that the carrier gas oxygen concentration monitored by the second oxygen measuring device is below 1% Vol.

[0038] In which, generally, the spray granulation drying method also includes a shutdown step S3: closing the first on-off component and stopping the feeding; opening the third on-off component and the fourth on-off component, closing the second on-off component and the fifth on-off component, until the material is emptied, and then closing the hot air furnace.

[0039] The fuel of the hot blast stove may be conventional in the art, and generally, the fuel of the hot blast stove may be natural gas or biogas.

[0040] On the basis of being in accordance with the common sense in the art, the above-mentioned preferred conditions can be arbitrarily combined to obtain the preferred embodiments of the present invention.

[0041] The reagents and raw materials used in the present invention are commercially available.

[0042] The positive and progressive effects of the present invention are:

[0043] 1) The spray granulation system drying system of the present application can exhaust air before feeding, so as to prepare hot flue gas from a hot blast furnace with lower cost and low oxygen concentration as replacement gas, thereby eliminating the potential risk of explosion;

[0044] 2) The spray granulation system drying system of the present application can directly send the non-condensable gas generated in the drying process into the hot air furnace for incineration, thereby reducing the emission of odorous gases, reducing equipment investment and operating costs, and improving system reliability.

[0045] 3) The drying system of the spray granulation system of the present application can make adjustments when the oxygen concentration of the internal circulating carrier gas increases, thereby ensuring safe production; in a preferred embodiment of the present application, the system of the present application can measure the oxygen concentration of the internal circulating carrier gas. BRIEF DESCRIPTION OF THE DRAWINGS

[0046] Figure 1 This is a schematic diagram of the spray granulation drying system in Example 1 of the present application.

[0047] Figure 2 Schematic diagram of the drying process of the spray granulation drying system in Example 2 of the present application.

[0048] Figure 3 This is a schematic diagram of the operation when the oxygen concentration of the carrier gas in the spray granulation drying system in Example 2 of the present application is too high.

[0049] Description of the drawings: 1 granulation and drying device, 101 feed port, 102 discharge port, 103 return port, 104 carrier gas outlet, 105 second carrier gas inlet, 106 first carrier gas inlet, 2 cyclone dust removal device, 201 discharge port, 3 carrier gas condensing device, 4 carrier gas circulation fan, 5 carrier gas bypass fan, 6 hot air furnace, 601 first flue gas inlet, 602 second flue gas inlet, 603 flue gas outlet, 7 heat exchanger, 8 flue gas induced draft fan, 918 first on-off component, 914 second on-off component, 912 third on-off component, 915 fourth on-off component, 917 fifth on-off component, 913 sixth on-off component, 911 seventh on-off component, 916 eighth on-off component, 1021 first oxygen measuring device, 1022 second oxygen measuring device, 11 flue gas purification device. DETAILED DESCRIPTION

[0050] The present invention is further described below by way of examples, but the present invention is not limited to the scope of the examples. The experimental methods in the following examples without specifying specific conditions are carried out according to conventional methods and conditions, or selected according to the product specifications.

[0051] Example 1 Spray Granulation Drying System

[0052] like Figure 1 The spray granulation drying system shown includes a granulation drying device 1 and a hot air furnace 6; the granulation drying device 1 is provided with a feed inlet 101, a first carrier gas inlet 106, a second carrier gas inlet 105 and a carrier gas outlet 104; the carrier gas outlet 104 of the granulation drying device 1 is connected to the cyclone dust removal device 2, the carrier gas condensation device 3 and the carrier gas circulation fan 4 in sequence through a pipeline; wherein the outlet pipeline of the carrier gas circulation fan 4 is divided into three routes: the first outlet pipeline is connected to the first carrier gas inlet 106; the second outlet pipeline is used to communicate with the atmosphere; and the third outlet pipeline; the hot air furnace is provided with a first smoke inlet 601, a second smoke inlet 602 and a smoke outlet 603; the carrier gas circulation fan 4 The third outlet pipe is connected to the first flue gas inlet 601 through the carrier gas bypass fan 5; the flue gas outlet 603 is connected to the hot fluid channel of the heat exchanger 7 and the flue gas induced draft fan 8 in sequence through the pipe; the outlet pipe of the flue gas induced draft fan 8 is divided into three routes: the fourth outlet pipe is connected to the second carrier gas inlet 105; the fifth outlet pipe is used to connect with the atmosphere; and the sixth outlet pipe is connected to the second flue gas inlet 602; the feed inlet 101, the second outlet pipe, the fourth outlet pipe and the fifth outlet pipe of the granulating drying device 1 are respectively connected with the first on-off component 918, the second on-off component 914, the third on-off component 912, the fourth on-off component 915 and the fifth on-off component 917.

[0053] In this embodiment, the granulation drying device 1 is provided with a discharge port 102. The granulation drying device is provided with a return port 103 for conveying the returned dried material. The cyclone dust removal device 2 is provided with a discharge port, and the discharge port of the cyclone dust removal device 2 is connected to the return port 103 of the granulation drying device 1.

[0054] In this embodiment, a first oxygen measuring device 1021 is provided on the outlet pipe of the carrier gas circulation fan 4. A sixth on-off component 913 is provided on the third outlet pipe. The first outlet pipe is connected to the first carrier gas inlet 106 via the heat exchanger 7. A seventh on-off component 911 is provided between the carrier gas condensing device 3 and the carrier gas circulation fan 4.

[0055] In this embodiment, the fifth outlet pipe is connected to the atmosphere through a flue gas purification device 11. The sixth outlet pipe is provided with an eighth on-off component 916. The pipe of the flue gas outlet 603 is provided with a second oxygen measuring device 1022. By setting the second oxygen measuring device 1022, when the oxygen concentration is detected to be higher than 1% Vol., the oxygen concentration can be adjusted by "opening the third on-off component 912 and the fourth on-off component 915, and closing the second on-off component 914 and the fifth on-off component 917" to ensure safe production.

[0056] In this embodiment, the on-off component is a regulating valve. At the same time, according to actual needs, a temperature measuring device, a pressure measuring device and a flow measuring device are added to the pipeline ( Figure 1 "T" represents temperature measuring device, "P" represents pressure measuring device, and "F" represents flow measuring device) to ensure safe operation of the system.

[0057] The spray granulation system drying system in this embodiment can exhaust air before feeding, so as to use the hot flue gas from the hot blast furnace with lower preparation cost and lower oxygen concentration as replacement gas, eliminating the potential risk of explosion; and during operation, the non-condensable gas generated in the drying process can be directly sent to the hot blast furnace for incineration, reducing the emission of odorous gases, reducing equipment investment and operating costs, and improving system reliability. When the oxygen concentration of the internal circulating carrier gas increases, the system in this embodiment can make adjustments, so as to ensure safe production. Example 2 Drying method of spray granulation drying system

[0058] The spray granulation drying system in Example 1 was used to dry the material.

[0059] The drying method of this embodiment comprises the following steps: Figure 2 When the system shown is operating normally:

[0060] Step S1: close the first on-off component 918, the second on-off component 914 and the fifth on-off component 917, open the third on-off component 912 and the fourth on-off component 915, and start the hot air furnace;

[0061] Step S2: When the spray granulation drying system runs to a carrier gas oxygen concentration of less than 1% Vol., close the third on-off component 912 and the fourth on-off component 915, and open the fifth on-off component 917; then open the second on-off component 914 and the first on-off component 918 respectively for feeding.

[0062] In this embodiment, in step S2 , the oxygen concentration of the carrier gas is measured by the first oxygen measuring device 1021 .

[0063] In this embodiment, when the oxygen content measured by the first oxygen measuring device 1021 is close to or exceeds 1% Vol., the third on-off component 912 and the fourth on-off component 915 are opened, and the second on-off component 914 and the fifth on-off component 917 are closed to cut into the flue gas, adjust the oxygen concentration, and ensure safe production; at the same time, the air distribution of the hot blast furnace 6 is adjusted to ensure that the oxygen content measured by the second oxygen measuring device 1022 is below 1% Vol.

[0064] In this embodiment, the spray granulation drying method also includes a shutdown step S3: closing the first on-off component 918 to stop adding material; opening the third on-off component 912 and the fourth on-off component 915, closing the second on-off component 914 and the fifth on-off component 917, allowing the flue gas to enter the internal circulation carrier gas, ensuring that the oxygen content measured by the second oxygen measuring device is within 1% Vol., and discharging the carrier gas to the atmosphere until the material is emptied, and then the hot air furnace and other on-off components can be closed.

[0065] In this embodiment, the fuel of the hot blast stove is natural gas.

[0066] In this embodiment, the wet material (compound fertilizer slurry) to be dried enters from the feed port 101 of the granulation drying device 1, and the high-temperature internal circulation carrier gas is fully mixed in the granulation drying device 1, rolled and rubbed into granules therein, and discharged from the discharge port 102 of the granulation drying device 1. The carrier gas discharged from the carrier gas outlet 104 of the granulation drying device 1 carries some small dust particles, which are treated by the cyclone dust removal device 2 to remove the particles (the particles can be discharged from the discharge port of the cyclone dust removal device 2 and returned to the granulation drying device 1 from the return port 103), enters the carrier gas condensation device 3 to cool down and remove the condensed water, and then is converted into a low-temperature internal circulation carrier gas (i.e., a low-temperature saturated wet carrier gas) with a relative humidity of 100%, and then enters the subsequent branch pipeline.

[0067] In this embodiment, in step S1, the sixth on-off component 913, the eighth on-off component 916 and the seventh on-off component 911 need to be turned on; after the hot blast furnace 6 is started, the oxygen concentration measured by the second oxygen measuring device 1022 is reduced to below 1% Vol.; at the same time, the flue gas continuously replaces the air in the system until the oxygen concentration measured by the first oxygen measuring device 1021 is also reduced to below 1% Vol.

[0068] In this embodiment, in step S2, after the switch adjustment of the above-mentioned on-off component, the flue gas of the hot blast furnace 6 can be cut off as the replacement gas to form a flue gas closed-loop circulation step; after feeding, the wet material will release non-condensable gas in the drying process of the granulation drying device 1, and gradually replace the flue gas in the internal circulation carrier gas; open the sixth on-off component 913; maintain the stable flow and mutual heat exchange between the internal circulation carrier gas and the external circulation flue gas; the oxygen content measured by the first oxygen measuring device 1021 gradually decreases in this process, and the oxygen concentration is stabilized to nearly 0% Vol. as an indicator that the internal circulation carrier gas has been completely replaced by non-condensable gas, and then enter the "dynamic balance step".

[0069] During normal system operation, if the Figure 3 When the oxygen concentration in the carrier gas is too high: when the oxygen content measured by the first oxygen measuring device 1021 is close to or exceeds 1% Vol, the third on-off component 912 and the fourth on-off component 915 are opened, and the second on-off component 914 and the fifth on-off component 917 are closed to cut into the flue gas, so as to ensure that the oxygen content in the flue gas measured by the second oxygen measuring device 1022 is below 1% Vol., so that the flue gas gradually dilutes the oxygen concentration until the oxygen content measured by the first oxygen measuring device 1021 drops below 1% Vol, and then the third on-off component 912 and the fourth on-off component 915 are closed, and the second on-off component 914 and the fifth on-off component 917 are opened, and the other steps are the same as the step of continuing to maintain dynamic balance.

[0070] In this embodiment, wet garbage fermentation biogas residue is combined with the nitrogen, phosphorus and potassium elements required in the final compound fertilizer to prepare a compound fertilizer slurry (water content 65%), and finally an organic-inorganic compound fertilizer is produced. According to the national standard "Organic-Inorganic Compound Fertilizer" (GB 18877-2009), the product "mass fraction of water (H2O) ≤ 12%", "particle size (1.00mm ~ 4.75mm or 3.35mm ~ 5.60mm) ≥ 70%", "ascaris egg mortality ≥ 95%", "fecal coliform count ≤ 100 / g", etc., that is, the product requires low moisture content, small particle size, and high temperature treatment. The dried product in this embodiment can meet the requirements of "Organic-Inorganic Compound Fertilizer" (GB 18877-2009).

Claims

1. A spray granulation drying system, characterized in that: It includes a granulation drying device and a hot air furnace; The granulation drying device is provided with a feed inlet, a first carrier gas inlet, a second carrier gas inlet and a carrier gas outlet; The carrier gas outlet of the granulation drying device is connected to a cyclone dust removal device, a carrier gas condensing device, and a carrier gas circulation fan in sequence through pipelines; wherein the outlet pipeline of the carrier gas circulation fan is divided into three routes: a first outlet pipeline is connected to the first carrier gas inlet; a second outlet pipeline is used to communicate with the atmosphere; and a third outlet pipeline; The hot blast stove is provided with a first smoke inlet, a second smoke inlet and a smoke outlet; The third outlet pipe of the carrier gas circulation fan is connected to the first flue gas inlet through the carrier gas bypass fan; the flue gas outlet is connected to the hot fluid channel of the heat exchanger and the flue gas induced draft fan in sequence through pipes; the outlet pipe of the flue gas induced draft fan is divided into three routes: a fourth outlet pipe is connected to the second carrier gas inlet; a fifth outlet pipe is used to connect to the atmosphere; and a sixth outlet pipe is connected to the second flue gas inlet; The feed port is provided with a first on-off component; the first outlet pipe is provided with a second on-off component; the second outlet pipe is provided with a third on-off component; the fourth outlet pipe is provided with a fourth on-off component; and the fifth outlet pipe is provided with a fifth on-off component. A first oxygen measuring device is provided on the outlet pipe of the carrier gas circulation blower; The spray granulation drying system also includes an oxygen concentration control module for implementing the following control steps: determining whether the oxygen concentration of the carrier gas monitored by the first oxygen measuring device is higher than 1% Vol., and if the determination is yes, executing the step of "opening the third on-off component and the fourth on-off component, and closing the second on-off component and the fifth on-off component"; and if the determination is no, executing the step of "closing the third on-off component and the fourth on-off component, and opening the second on-off component and the fifth on-off component".

2. The spray granulation drying system according to claim 1, characterized in that: The granulation and drying device is provided with a discharge port.

3. The spray granulation drying system according to claim 1, characterized in that: The granulation drying device is provided with a material return port.

4. The spray granulation drying system according to claim 3, characterized in that: The cyclone dust removal device is provided with a discharge port, and the discharge port of the cyclone dust removal device is communicated with the return port of the granulation drying device.

5. The spray granulation drying system according to claim 1, characterized in that: The first outlet pipe is connected to the first carrier gas inlet through the cold fluid channel of the heat exchanger; And / or, a sixth on-off component is provided on the third outlet pipe; And / or, a seventh on-off component is provided between the carrier gas condensing device and the carrier gas circulation fan; and / or, the fifth outlet pipe is connected to the atmosphere through a flue gas purification device; And / or, an eighth on-off component is provided on the sixth outlet pipe; And / or, a second oxygen measuring device is provided on the flue gas outlet pipe.

6. A spray granulation drying method, characterized in that: The spray granulation drying system according to any one of claims 1 to 5 is used for drying, and the drying process comprises the following steps: adding the material to be dried into the granulation drying device and drying the material.

7. The spray granulation drying method according to claim 6, wherein: Before the material to be dried is added to the granulation drying device, the drying method further comprises the following steps: Step S1: closing the first on-off component, the second on-off component, and the fifth on-off component, opening the third on-off component and the fourth on-off component, and starting the hot air furnace; Step S2: When the spray granulation drying system operates until the oxygen concentration of the carrier gas therein is below 1% Vol., the third on-off component and the fourth on-off component are closed, and the first on-off component, the second on-off component and the fifth on-off component are opened.

8. The spray granulation drying method according to claim 7, wherein: In step S2, the fifth on-off component is first turned on, and then the first on-off component and the second on-off component are turned on respectively; And / or, a sixth on-off component is provided on the third outlet pipe; a seventh on-off component is provided between the carrier gas condensing device and the carrier gas circulation blower; an eighth on-off component is provided on the sixth outlet pipe; and step S1 further includes the steps of opening the seventh on-off component and the eighth on-off component, and closing the sixth on-off component; And / or, in step S2, the oxygen concentration of the carrier gas is monitored by the first oxygen measuring device.

9. The spray granulation drying method according to claim 7, wherein: The spray granulation drying method further includes a shutdown step S3: closing the first on-off component and stopping feeding; opening the third on-off component and the fourth on-off component, and closing the second on-off component and the fifth on-off component until the material is emptied, and then closing the hot air furnace.

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