Spray drying exhaust heat recycling device

Abstract

The invention provides a spray drying exhaust heat recycling device, and belongs to the field of spray drying tower tail gas heat recovery, and the spray drying exhaust heat recycling device comprises a first heat exchange system, a cloth bag dust removal system, a dust recovery system and a spray drying system, the dust recovery system comprises a water tank connected with a flue gas outlet of the first heat exchange system and a water tank connected with the water tank; according to the device, resources in tail gas are fully recycled; the flue gas outlet and the fresh air inlet of the first heat exchange system are provided with the second heat exchanger and the third heat exchanger correspondingly, the second heat exchanger is connected with the third heat exchanger, and the third heat exchanger is connected with the dust recovery system. And the fuel quantity required by the whole system is greatly reduced. According to the tail gas recycling device, resources in tail gas can be efficiently recycled, the problem that the tail gas resources are not fully utilized is effectively solved, and the production cost is also reduced.

Description

Technical Field

[0001] The present application relates to the technical field of heat recovery of tail gas from a spray drying tower, and in particular to a spray drying exhaust gas heat recycling device. Background Art

[0002] The spray drying equipment used in the lithium iron phosphate production process usually uses a natural gas combustion furnace to heat the air to about 260-280°C, and then passes it into a drying tower to dry the material, and the dried tail gas is directly discharged. However, the temperature of these tail gases is between 80 and 90°C, and the tail gas also contains a large amount of moisture and a small amount of material dust. Direct discharge is bound to cause a lot of waste. At present, there are many studies on the heat recovery of tail gas in the spray drying system. In the prior art, although it has been proposed to use a waste heat exchanger to exchange heat with the tail gas to achieve heat reuse, the actual heat recovery rate is low, and because the tail gas components are not easy to separate, it cannot guarantee the full recovery of moisture and materials.

[0003] In view of this, it is necessary to design a spray drying exhaust heat recycling device to solve the above problems. Summary of the invention

[0004] In view of the technical problems existing in the background technology, the present application provides a spray drying exhaust heat recycling device, which fully recovers and recycles the heat, water and dust in the spray drying exhaust gas, which not only saves fuel and water, but also is beneficial to environmental protection.

[0005] In a first aspect, an embodiment of the present application provides a spray drying exhaust heat recycling device, comprising: a first heat exchange system, a bag dust removal system connected to the smoke inlet of the first heat exchange system, a dust recovery system connected to the smoke outlet of the first heat exchange system, a spray drying system connected to the fresh air outlet of the first heat exchange system, a second heat exchanger arranged at the smoke outlet of the first heat exchange system, and a third heat exchanger connected to the water outlet of the second heat exchanger; the spray drying system is connected to the bag dust removal system;

[0006] The dust recovery system includes a water tank connected to the smoke outlet of the first heat exchange system and a water tank connected to a water outlet of the water tank; the water outlet of the water tank is connected to the water inlet of the second heat exchanger through a pipe; the water outlet of the third heat exchanger is connected to the water inlet of the water tank; the third heat exchanger is placed at the fresh air inlet of the first heat exchange system.

[0007] In the technical solution of the embodiment of the present application, a first heat exchange system is set up, and the flue gas inlet, flue gas outlet and fresh air outlet of the first heat exchange system are respectively connected to the bag dust removal system, the dust recovery system and the spray drying system, and a second heat exchanger is set at the flue gas outlet of the first heat exchange system, and the water outlet of the second heat exchanger is connected to the third heat exchanger, wherein the dust recovery system is composed of a water tank connected to the first heat exchange system and a water tank connected to the water tank, and the water outlet of the water tank is also connected to the second heat exchanger; in this way, the waste heat in the exhaust gas is absorbed by multiple heat exchange systems in turn, and then used to supply energy for the heating process of the entire system in the combustion furnace. This multi-stage heat exchange heat exchange method realizes full and efficient recovery of the exhaust gas heat. At the same time, it greatly reduces the amount of fuel required for the heating process in the combustion furnace of the entire system, and realizes the efficient recycling of energy; in addition, after the exhaust gas containing a certain amount of dust enters the first heat exchange system and exchanges heat with the first heat exchange system, the dust follows the condensed water in the exhaust gas and drips through the flue gas outlet. The condensed water droplets can absorb the ultrafine dust in the entire device and enter the water tank and water tank in turn for subsequent processing, thereby recovering the fine powder escaping from the entire system, thus playing the role of a water film dust collector to recycle materials; moreover, the water in the third heat exchanger and the condensed water in the exhaust gas will flow to the water tank, so that the dust and water escaping here in the exhaust gas can be fully recovered into the water tank again.

[0008] In some embodiments, the first heat exchange system includes a first heat exchanger and a spray device disposed above the first heat exchanger.

[0009] In this embodiment, by arranging a spray device on the first heat exchanger, not only can the dust accumulated on the plates of the first heat exchanger be washed away, thereby reducing the risk of the plates of the first heat exchanger being blocked; the escaped dust can also be settled through the spraying action and collected in a water tank for recycling again.

[0010] In some embodiments, a chimney connected to the water tank is provided on one side of the water tank.

[0011] In this embodiment, a chimney connected to the water tank is provided on one side of the water tank, so that the exhaust gas can be heat exchanged and the dust can drip into the water tank through the flue gas outlet along with the condensed water in the exhaust gas. After all the heat and dust in the exhaust gas are received by the water tank, only the flue gas can enter the chimney, thereby efficiently ensuring the recovery of exhaust gas resources.

[0012] In some embodiments, a first pressure transmitter is disposed on the chimney, and a second pressure transmitter is disposed on the first heat exchange system.

[0013] In this embodiment, by respectively arranging pressure transmitters on the first heat exchange system and the chimney, when it is detected that the pressure difference at both ends of the first heat exchange system exceeds the standard, the spray device will be automatically turned on to spray the first heat exchange system to reduce the resistance of the first heat exchanger and enable the equipment to operate normally.

[0014] In some embodiments, a water outlet 1 of the water tank is connected to a water inlet of the second heat exchanger through a first pipe, and a water pump 1 and a first valve are provided on the first pipe.

[0015] In this embodiment, by connecting the water outlet of the water tank with the water inlet of the second heat exchanger, a large amount of condensed water precipitated from the exhaust gas after cooling and a large amount of water generated during the spraying process can be collected and recycled for multi-stage heat exchange of the exhaust gas, which can greatly save the amount of water required for heat exchange of the entire system.

[0016] In some embodiments, the second water outlet of the water tank is connected to an external discharge pipeline via a second pipe, a third valve is provided on the second pipe, and the height of the first water outlet of the water tank is higher than the height of the second water outlet.

[0017] In this embodiment, by connecting the water tank to the external discharge pipeline through a pipe at water outlet 2 which is lower than water outlet 1 in height, the dust deposited in the water tank can be subsequently recovered and utilized without affecting the reuse of the supernatant water in the water tank.

[0018] In some embodiments, the water outlet of the water tank is connected to a circulation pipe through a first pipe, and is connected to a water inlet of the second heat exchanger through the circulation pipe. A first valve is provided on the first pipe.

[0019] In this embodiment, the water tank is connected to the water inlet of the second heat exchanger through the first pipeline and the circulation pipeline in sequence, and a first valve is set on the first pipeline, which can facilitate subsequent branching to install other functional pipelines, thereby making the layout of the entire pipeline system more concise.

[0020] In some embodiments, the second water outlet of the water tank is connected to the circulation pipe through a second pipe, a branch pipe is provided on the circulation pipe to connect to the external discharge pipe, and a third valve is provided on the second pipe; the height of the first water outlet of the water tank is higher than the height of the second water outlet;

[0021] A water pump 1 is arranged on the circulation pipeline, and a second valve is arranged on the circulation pipeline and between the water tank and the external discharge pipeline.

[0022] In this embodiment, by connecting the second water outlet of the water tank to the circulation pipeline, connecting the branch pipeline of the circulation pipeline to the external discharge pipeline, and providing corresponding valves and / or water pumps on each pipeline, the entire pipeline system is arranged more simply. Only by controlling the switching of each valve, the supernatant in the water tank can be accurately recycled and the dust in the water tank can be recovered and processed, and the functional blocks do not affect each other.

[0023] In some embodiments, a branch port of the first air duct for connecting the bag dust removal system and the first heat exchange system is connected to a branch port of the chimney through a bypass air duct; a first air valve is provided on the chimney between the branch port of the chimney and the water tank; a second air valve is provided on the bypass air duct; and a third air valve is provided on the first air duct between the branch port of the first air duct and the smoke inlet of the first heat exchange system.

[0024] In this embodiment, the branch port of the first air duct and the branch port of the chimney are connected through a bypass air pipe, and air valves are respectively provided on the chimney, the bypass air pipe and the first air duct. When the pressure difference at both ends of the first heat exchange system still exceeds the standard after the spraying device sprays the first heat exchange system, the exhaust gas is directly discharged through the bypass air pipe and the chimney to release the pressure, thereby serving as an emergency channel to protect the safe operation of the equipment and prevent the entire system from exploding.

[0025] In some embodiments, the bag dust removal system includes a bag dust collector connected to the spray drying system, a dust detector arranged on the first air duct, and the dust detector is located between the first air duct branch port and the bag dust collector.

[0026] In this embodiment, a dust detector is arranged between the first air duct branch port and the bag-type dust collector. When the dust detector detects that the dust concentration in the air duct exceeds the standard, it will alarm the operator and prompt the bag-type dust collector to fail and need to be shut down for maintenance. At the same time, the spray device is automatically turned on to spray and remove dust from the material leaked from the bag-type dust collector into the first heat exchange system. This not only recycles the material, but also avoids the pollution of the environment caused by the leaked material.

[0027] The above description is only an overview of the technical solution of the present application. In order to more clearly understand the technical means of the present application, it can be implemented in accordance with the contents of the specification. In order to make the above and other purposes, features and advantages of the present application more obvious and easy to understand, the specific implementation methods of the present application are listed below. BRIEF DESCRIPTION OF THE DRAWINGS

[0028] In order to more clearly illustrate the technical solution of the present application, the following is a brief introduction to the drawings used in the present application. Obviously, the drawings described below are only some embodiments of the present application, and for ordinary technicians in this field, other drawings can be obtained based on these drawings without creative work.

[0029] Figure 1 This is a schematic diagram of the structure of the spray drying exhaust heat recycling device in the embodiment of the present application;

[0030] Description of reference numerals:

[0031] 11. First heat exchanger; 12. Spraying device; 121. Water pump 2; 13. Second pressure transmitter; 21. Bag filter; 22. Dust detector; 23. Draft fan; 31. Water tank; 32. Water tank; 33. First pipeline; 331. First valve; 34. Second pipeline; 341. Third valve; 35. Circulation pipeline; 351. Second valve; 352. Water pump 1; 36. External discharge pipeline; 361. Fourth valve; 4. Second heat exchanger; 5. Third heat exchanger; 61. Combustion furnace; 62. Drying tower; 7. Chimney; 71. First pressure transmitter; 72. First air valve; 8. First air duct; 81. Third air valve; 9. Bypass air duct; 91. Second air valve; 10. Blower. DETAILED DESCRIPTION

[0032] The following embodiments of the technical solution of the present application are described in detail in conjunction with the accompanying drawings. The following embodiments are only used to more clearly illustrate the technical solution of the present application, and are therefore only used as examples, and cannot be used to limit the scope of protection of the present application.

[0033] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by technicians in the technical field to which this application belongs; the terms used herein are only for the purpose of describing specific embodiments and are not intended to limit this application; the terms "including" and "having" in the specification and claims of this application and the above-mentioned figure descriptions and any variations thereof are intended to cover non-exclusive inclusions.

[0034] In the description of the embodiments of the present application, the technical terms "first", "second", etc. are only used to distinguish different objects, and cannot be understood as indicating or implying relative importance or implicitly indicating the number, specific order or primary and secondary relationship of the indicated technical features. In the description of the embodiments of the present application, the meaning of "multiple" is more than two, unless otherwise clearly and specifically defined.

[0035] Reference to "embodiments" herein means that a particular feature, structure, or characteristic described in conjunction with the embodiments may be included in at least one embodiment of the present application. The appearance of the phrase in various locations in the specification does not necessarily refer to the same embodiment, nor is it an independent or alternative embodiment that is mutually exclusive with other embodiments. It is explicitly and implicitly understood by those skilled in the art that the embodiments described herein may be combined with other embodiments.

[0036] In the description of the embodiments of the present application, the term "and / or" is only a description of the association relationship of the associated objects, indicating that there may be three relationships. For example, A and / or B can represent: A exists alone, A and B exist at the same time, and B exists alone. In addition, the character " / " in this article generally indicates that the associated objects before and after are in an "or" relationship.

[0037] In the description of the embodiments of the present application, the term "multiple" refers to more than two (including two). Similarly, "multiple groups" refers to more than two groups (including two groups), and "multiple pieces" refers to more than two pieces (including two pieces).

[0038] In the description of the embodiments of the present application, the technical terms "center", "longitudinal", "lateral", "length", "width", "thickness", "up", "down", "front", "back", "left", "right", "vertical", "horizontal", "top", "bottom", "inside", "outside", "clockwise", "counterclockwise", "axial", "radial", "circumferential", etc. indicate orientations or positional relationships based on the orientations or positional relationships shown in the accompanying drawings, which are only for the convenience of describing the embodiments of the present application and simplifying the description, and do not indicate or imply that the referred device or element must have a specific orientation, be constructed and operated in a specific orientation, and therefore should not be understood as a limitation on the embodiments of the present application.

[0039] In the description of the embodiments of the present application, unless otherwise clearly specified and limited, technical terms such as "installed", "connected", "connected", "fixed" and the like should be understood in a broad sense. For example, it can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection or an electrical connection; it can be a direct connection or an indirect connection through an intermediate medium, and it can be the internal connection of two elements or the interaction relationship between two elements. For those of ordinary skill in the art, the specific meanings of the above terms in the embodiments of the present application can be understood according to the specific circumstances.

[0040] In the process of recycling energy, the devices used to treat tail gas in the prior art have low heat exchange rate and insufficient recovery of dust and water in the system, which not only wastes resources but also easily pollutes the environment. Therefore, it is particularly important to rationalize the design to efficiently recycle the resources in these tail gases.

[0041] In order to solve the above-mentioned technical problems, the present application provides a spray drying exhaust heat recycling device, which is provided by setting a first heat exchange system, and connecting the bag dust removal system, the dust recovery system, and the spray drying system at the flue gas inlet, the flue gas outlet, and the fresh air outlet of the first heat exchange system respectively, and setting a second heat exchanger 4 at the flue gas outlet of the first heat exchange system, and the water outlet of the second heat exchanger 4 is connected to the third heat exchanger 5, wherein the dust recovery system is composed of a water tank 31 connected to the flue gas outlet of the first heat exchange system, and a water tank 32 connected to the water outlet of the water tank 31, and the water outlet of the water tank 32 is connected to the water inlet of the second heat exchanger 4, so that after the waste heat in the exhaust gas is recovered, the moisture in the exhaust gas is condensed, and the condensed water falls into the water tank 32 with the dust in the exhaust gas, thereby achieving the technical effect of recovering heat, moisture and materials in the exhaust gas.

[0042] For the convenience of description, the following embodiments are described by taking a spray drying exhaust gas heat recycling device according to an embodiment of the present application as an example.

[0043] Please refer to Figure 1 , Figure 1The schematic structural diagram of the spray drying exhaust heat recycling device provided in the embodiment of the present application comprises: a first heat exchange system, a bag dust removal system connected to the smoke inlet of the first heat exchange system through a first air duct 8, a dust recovery system connected to the smoke outlet of the first heat exchange system, a spray drying system connected to the fresh air outlet of the first heat exchange system through an air duct, a second heat exchanger 4 arranged at the smoke outlet of the first heat exchange system, a third heat exchanger 5 connected to the water outlet of the second heat exchanger 4, the third heat exchanger 5 is placed at the fresh air inlet of the first heat exchange system, and the spray drying system is connected to the bag dust removal system through an air duct; in this way, the waste heat in the exhaust gas is absorbed by the first heat exchange system The first heat exchange system uses the absorbed waste heat to preheat the air coming in from the fresh air inlet, thereby realizing the first-level heat exchange of the exhaust gas; the exhaust gas after the first heat exchange (the temperature drops to 50-60°C) enters the water tank 31 and then exchanges heat with the second heat exchanger 4. The water in the second heat exchanger 4 is heated and then flows to the third heat exchanger 5 through the pipeline. The heat exchanged by the third heat exchanger 5 preheats the air entering the first heat exchange system, thereby realizing the second-level heat exchange of the exhaust gas; this multi-stage heat exchange method realizes the full and efficient recovery of the exhaust gas heat, and the amount of fuel required for the heating process in the combustion furnace 61 of the entire system can be greatly reduced. Experimental verification shows that the energy saving rate can reach 18% to 25%. In some embodiments of the present application, the dust recovery system includes a water tank 31 connected to the flue gas outlet of the first heat exchange system, and a water tank 32 connected to the water outlet of the water tank 31; the water outlet of the water tank 32 is connected to the water inlet of the second heat exchanger 4 through a pipe; the water outlet of the third heat exchanger 5 is connected to the water inlet of the water tank 32; the third heat exchanger 5 is placed at the fresh air inlet of the first heat exchange system; after the exhaust gas enters the first heat exchange system, the heat in the exhaust gas is absorbed by the first heat exchange system, and the temperature of the exhaust gas drops to 50-60°C after heat exchange, at which time the moisture in the exhaust gas is condensed to form condensed water, and then the condensed water falls into the dust recovery system with the dust in the exhaust gas, thereby realizing the recovery of heat, moisture and materials in the exhaust gas. In addition, the water in the third heat exchanger 5 and the condensed water in the tail gas will flow to the water tank 32, so that the dust and water escaping from the tail gas can be fully recovered again in the water tank 32. It has been verified through experiments that after the tail gas is heat exchanged, a large amount of condensed water can be precipitated after the tail gas containing water is cooled, and the water volume is about 0.2-0.4T / h. As the condensed water in the tail gas precipitates and drips, the condensed water droplets can absorb the ultrafine dust in the entire device, and the dust will settle into the dust recovery system with the condensed water, thereby recovering the fine powder escaping from the device, thus playing the role of a water film dust collector to recover materials.

[0044] After the dust enters the water tank 31 along with the condensed water, it flows into the water tank 32 and sinks to the bottom of the water tank 32 to be recycled; and the upper clarified liquid in the water tank 32 can be sent to the second heat exchanger 4 for reuse, thus realizing the rational reuse of the water and dust in the exhaust gas.

[0045] In some embodiments of the present application, the spray drying system includes a combustion furnace 61 connected to the fresh air outlet of the first heat exchange system through an air duct, and a drying tower 62 connected to the outlet of the combustion furnace 61 through an air duct; the outlet of the drying tower 62 is connected to the bag dust removal system through an air duct.

[0046] In some embodiments of the present application, the second heat exchanger 4 and the third heat exchanger 5 both include fin-tube heat exchangers; the use of fin-tube heat exchangers increases the heat exchange area and reduces the heat transfer resistance, thereby significantly improving the efficiency of heat transfer, and the compact structure can save space and reduce equipment costs. The heat exchange medium in the second heat exchanger 4 and the third heat exchanger 5 both includes condensed water; this makes it possible to effectively reduce the cost of water treatment and energy consumption when the high-temperature condensed water is recycled and utilized, and also improve the efficiency of heat use.

[0047] In some embodiments of the present application, the fresh air inlet of the first heat exchange system is connected to the blower 10 through an air duct, and the third heat exchanger 5 is placed at the air inlet of the blower 10; in this way, the fresh air entering the blower 10 is heated by the hot water in the third heat exchanger 5 and is sent into the first heat exchange system more quickly.

[0048] Further, in the embodiments of the present application, Figure 1 As shown, the first heat exchange system includes a first heat exchanger 11 and a spray device 12 arranged above the first heat exchanger 11; this can not only wash away the dust accumulated on the plates of the first heat exchanger 11 and reduce the risk of the plates of the first heat exchanger 11 being blocked, but also can settle the escaped dust through the spraying effect and collect it in the water tank 32 for recycling again.

[0049] In some embodiments of the present application, the first heat exchanger 11 includes an air-to-air heat exchanger, which has a high heat transfer efficiency and low energy consumption. A water pump 121 is provided on the pipeline for supplying water to the spray device 12, so that it is convenient to provide the spray device 12 with water sent from other water sources.

[0050] Further, in the embodiments of the present application, Figure 1As shown, one side of the water tank 31 is provided with a chimney 7 connected to the water tank 31; in this way, the exhaust gas can be heat exchanged, and the dust can follow the condensed water in the exhaust gas and drip into the water tank 31 through the flue gas outlet, so that the heat and dust in the exhaust gas are all received by the water tank 31. Then, the gas-liquid immiscibility is used to ensure that only the flue gas can enter the chimney 7, thereby effectively ensuring the recovery of exhaust gas resources and ensuring the cleanliness of exhaust gas emissions.

[0051] Further, in the embodiments of the present application, Figure 1 As shown, the chimney 7 is provided with a first pressure transmitter 71, and the first heat exchange system is provided with a second pressure transmitter 13. When it is detected that the pressure difference at both ends of the first heat exchange system exceeds the standard, the spray device 12 will be automatically turned on to spray the first heat exchange system to reduce the resistance of the first heat exchanger 11, which is beneficial to the normal operation of the equipment.

[0052] Further, in the embodiments of the present application, Figure 1 As shown, the water outlet of the water tank 32 is connected to the water inlet of the second heat exchanger 4 through the first pipe 33, and the first pipe 33 is provided with a water pump 352 and a first valve 331, so that the condensed water precipitated from the exhaust gas after cooling and the water generated during the spraying process are collected and recycled for multi-stage heat exchange of the exhaust gas, which can greatly save the amount of water required for heat exchange of the entire system.

[0053] Further, in the embodiments of the present application, Figure 1 As shown, the second water outlet of the water tank 32 is connected to the external discharge pipe 36 through the second pipe 34, and the third valve 341 is provided on the second pipe 34. The height of the water outlet 1 of the water tank 32 is higher than the height of the water outlet 2. In this way, the dust deposited in the water tank 32 can be subsequently recovered and utilized without affecting the reuse of the supernatant water in the water tank 32.

[0054] Further, in the embodiments of the present application, Figure 1 As shown, the water outlet of the water tank 32 is connected to the circulation pipe 35 through the first pipe 33, and is connected to the water inlet of the second heat exchanger 4 through the circulation pipe 35. The first pipe 33 is provided with a first valve 331, which is convenient for subsequent branching to install other functional pipes, thereby making the layout of the entire pipe system more concise.

[0055] Further, in the embodiments of the present application, Figure 1 As shown, the second water outlet of the water tank 32 is connected to the circulation pipe 35 through the second pipe 34, the circulation pipe 35 is provided with a branch pipe connected to the external discharge pipe 36, and the second pipe 34 is provided with a third valve 341; the height of the first water outlet of the water tank 32 is higher than the height of the second water outlet;

[0056] The circulation pipeline 35 is provided with a water pump 1 352, and a second valve 351 is provided on the circulation pipeline 35 and between the water tank 31 and the external discharge pipeline 36; the external discharge pipeline 36 is provided with a fourth valve 361;

[0057] During normal production, the first valve 331 and the second valve 351 are opened, and the third valve 341 and the fourth valve 361 are closed at the same time, and the water pump 1 352 extracts the supernatant of the water tank 32 for heat exchange between the second heat exchanger 4 and the third heat exchanger 5; when the dust in the water tank 32 reaches a certain concentration, after the water tank 32 is stirred, the third valve 341 and the fourth valve 361 are opened, and the first valve 331 and the second valve 351 are closed at the same time, and the water containing the material is discharged from the external discharge pipe 36 to the previous process for use, so as to realize the recovery of dust materials; in this way, under the premise of making the entire pipeline system more concise, only by controlling the opening and closing of each valve, the recycling of the supernatant in the water tank 32 and the recovery of the dust in the water tank 32 can be accurately realized, and the functional blocks do not affect each other.

[0058] In some embodiments of the present application, the external exhaust pipe 36 can be connected to the pipe used to supply water to the spray device 12. In this way, the recovered water can not only be used for heat exchange, but also provide water source for the spray device 12 in the first heat exchange system. Such recycling and repeated utilization can further efficiently avoid the waste of water resources.

[0059] Further, in the embodiments of the present application, Figure 1 As shown, the branch port of the first air duct 8 for connecting the bag dust removal system and the first heat exchange system is connected to the branch port of the chimney 7 through a bypass air pipe 9; a first air valve 72 is provided on the chimney 7 between the branch port of the chimney 7 and the water tank 31; a second air valve 91 is provided on the bypass air pipe 9; a third air valve 81 is provided on the first air duct 8 between the branch port of the first air duct 8 and the smoke inlet of the first heat exchange system; when the pressure difference value between the second pressure transmitter 13 on the first heat exchange system and the first pressure transmitter 71 on the chimney 7 exceeds the standard, the water pump 121 is first turned on to spray the first heat exchanger 11 through the spray device 12; when the pressure difference still exceeds the standard, the system automatically opens the second air valve 91, closes the first air valve 72 and the third air valve 81, and switches to the bypass air pipe 9, so that the exhaust gas is directly discharged through the bypass air pipe 9 and the chimney 7 to release the pressure, so as to serve as an emergency channel to protect the safe operation of the equipment and prevent the entire system from exploding.

[0060] Further, in the embodiments of the present application, Figure 1As shown, the bag-type dust removal system includes a bag-type dust collector 21 connected to the spray drying system, and a dust detector 22 arranged on the first air duct 8, and the dust detector 22 is located between the branch port of the first air duct 8 and the bag-type dust collector 21; when the dust detector 22 detects that the dust concentration in the air duct exceeds the standard, it will alarm the operator to remind the operator that the bag-type dust collector 21 has a fault and needs to be shut down for maintenance. At the same time, the water pump 21 is automatically started, and the material leaked from the bag-type dust collector 21 to the first heat exchange system is sprayed and dusted through the spray device 12. This not only recycles the material, but also avoids the pollution of the environment caused by the leaked material.

[0061] In some embodiments of the present application, the bag dust removal system also includes an induced draft fan 23 arranged on the first air duct 8, and the induced draft fan 23 is located between the dust detector 22 and the bag dust collector 21, so that the exhaust gas in the bag dust collector 21 can be delivered into the first heat exchange system more quickly through the induced draft fan 23.

[0062] The working principle of a spray drying exhaust heat recycling device provided by the present application is described below: Figure 1 As shown,

[0063] 1. When the waste heat of the tail gas is recovered, the first air valve 72 and the third air valve 81 are opened, and the second air valve 91 is closed at the same time. The fresh air enters the first heat exchanger 11 and the combustion furnace 61 in sequence through the air duct from the blower 10. After the fresh air is heated to the process temperature in the combustion furnace 61, it enters the drying tower 62 through the air duct to dry the material. After the drying, the material enters the bag filter 21 through the air duct with the tail gas for dust removal, thereby realizing the separation of the tail gas and the material. The tail gas passes through the induced draft fan 23 and the first air duct 8 into the first heat exchanger 11. At this time, after the heat in the tail gas is absorbed by the first heat exchange system, the first heat exchange system uses the absorbed waste heat to preheat the air coming in from the fresh air inlet, thereby realizing the first-level heat exchange of the tail gas; wherein, the preheated air enters the combustion furnace 61 through the pipeline. After the first heat exchange, the tail gas (temperature drops to 50-60°C) enters the water tank 31 and exchanges heat with the second heat exchanger 4. The water in the second heat exchanger 4 is heated and then flows to the third heat exchanger 5 through the pipeline. The heat exchanged by the third heat exchanger 5 preheats the air entering the first heat exchange system, thus realizing the secondary heat exchange of the tail gas. Finally, the tail gas is discharged through the chimney 7, and the water in the third heat exchanger 5 returns to the water tank 32 through the pipeline.

[0064] 2. During normal production, the first valve 331 and the second valve 351 are opened, and the third valve 341 and the fourth valve 361 are closed at the same time. The water pump 352 extracts the supernatant from the water tank 32 for heat exchange in the second heat exchanger 4 and the third heat exchanger 5. When the dust in the water tank 32 reaches a certain concentration, the water tank 32 is stirred, and the third valve 341 and the fourth valve 361 are opened, and the first valve 331 and the second valve 351 are closed at the same time. The water containing the material is discharged from the external discharge pipeline 36 to the previous process for use, thereby realizing dust material recovery.

[0065] 3. When the heat exchange system is under maintenance or is abnormal, the second air valve 91 is opened, and the first air valve 72 and the third air valve 81 are closed. The exhaust gas does not pass through the heat exchanger but is directly discharged through the chimney 7, which does not affect the normal operation of the spray drying system.

[0066] 3. When the pressure difference between the second pressure transmitter 13 on the first heat exchange system and the first pressure transmitter 71 on the chimney 7 exceeds the standard, first turn on the water pump 121 to spray the first heat exchanger 11 through the spray device 12; when the pressure difference still exceeds the standard, the system automatically opens the second air valve 91, closes the first air valve 72 and the third air valve 81, and switches to the bypass air pipe 9, so that the exhaust gas is directly discharged through the bypass air pipe 9 and the chimney 7 to release the pressure, which serves as an emergency channel to protect the safe operation of the equipment and prevent the entire system from exploding.

[0067] Please also read Figure 1 According to one or more embodiments of the present application, the spray drying exhaust heat recycling device provided by the present application is composed of a first heat exchange system, a second heat exchanger 4, a third heat exchanger 5, a bag dust removal system, a dust recovery system, and a spray drying system to form a complete heat recycling device; the environmental pollution is small when the exhaust gas is treated throughout the whole process, and it can ensure that the resources in the exhaust gas are fully recovered.

[0068] A second heat exchanger 4 and a third heat exchanger 5 are respectively arranged at the flue gas outlet and the fresh air inlet of the first heat exchange system, and the water outlet of the second heat exchanger 4 is connected to the third heat exchanger 5, and the water outlet of the third heat exchanger 5 is connected to the dust recovery system, so that the waste heat absorbed by multiple heat exchangers in the exhaust gas can supply energy to the combustion furnace 61. This multi-stage heat exchange method can achieve full and efficient recovery of the exhaust gas heat while greatly reducing the amount of fuel required for the heating process of the entire system in the combustion furnace 61, thereby achieving efficient recycling of energy.

[0069] In addition, the dust recovery system is composed of a water tank 31 connected to the first heat exchange system and a water tank 32 connected to the water tank 31. The water outlet of the water tank 32 is connected to the water inlet of the second heat exchanger 4, and the water outlet of the third heat exchanger 5 is connected to the water tank 32. After the waste heat in the tail gas is absorbed by the first heat exchange system, the dust follows the condensed water in the tail gas and drips through the flue gas outlet into the water tank 31, and then enters the water tank 32 for subsequent processing, so that the fine powder escaping from the entire system can be recovered. The water in the third heat exchanger 5 and the condensed water in the tail gas will flow to the water tank 32, so that the dust and water escaping from the tail gas can be fully recovered again into the water tank 32.

[0070] The entire device can start different equipment at different time periods according to different working conditions. In addition, it has a high degree of automation, easy operation, stable operation, safety and reliability, energy saving and environmental protection, effectively reducing manual labor intensity and production costs, and has good energy-saving and emission reduction effects.

[0071] It should be noted that the present application is not limited to the above-mentioned embodiments. The above-mentioned embodiments are only examples, and the embodiments having the same structure as the technical idea and exerting the same effect within the scope of the technical solution of the present application are all included in the technical scope of the present application. In addition, without departing from the scope of the main purpose of the present application, various modifications that can be thought of by those skilled in the art to the embodiments and other methods of combining some of the constituent elements in the embodiments are also included in the scope of the present application.

Claims

1. A spray drying exhaust heat recycling device, characterized in that: include: a first heat exchange system, a bag dust removal system connected to the smoke inlet of the first heat exchange system, a dust recovery system connected to the smoke outlet of the first heat exchange system, a spray drying system connected to the fresh air outlet of the first heat exchange system, a second heat exchanger (4) arranged at the smoke outlet of the first heat exchange system, and a third heat exchanger (5) connected to the water outlet of the second heat exchanger (4); the spray drying system is connected to the bag dust removal system; The dust recovery system comprises a water tank (31) connected to the smoke outlet of the first heat exchange system, and a water tank (32) connected to a water outlet of the water tank (31); a water outlet of the water tank (32) is connected to a water inlet of a second heat exchanger (4) through a pipeline; a water outlet of the third heat exchanger (5) is connected to a water inlet of the water tank (32); and the third heat exchanger (5) is placed at the fresh air inlet of the first heat exchange system.

2. The spray drying exhaust heat recycling device according to claim 1, characterized in that: The first heat exchange system comprises a first heat exchanger (11) and a spray device (12) arranged above the first heat exchanger (11).

3. The spray drying exhaust heat recycling device according to claim 2, characterized in that: A chimney (7) connected to the water tank (31) is provided on one side of the water tank (31).

4. The spray drying exhaust heat recycling device according to claim 3, characterized in that: The chimney (7) is provided with a first pressure transmitter (71), and the first heat exchange system is provided with a second pressure transmitter (13).

5. The spray drying exhaust heat recycling device according to claim 1, characterized in that: The water outlet 1 of the water tank (32) is connected to the water inlet of the second heat exchanger (4) through a first pipe (33), and a water pump 1 (352) and a first valve (331) are provided on the first pipe (33).

6. The spray drying exhaust heat recycling device according to claim 5, characterized in that: The second water outlet of the water tank (32) is connected to an external discharge pipeline (36) via a second pipe (34), a third valve (341) is provided on the second pipe (34), and the height of the first water outlet of the water tank (32) is higher than the height of the second water outlet.

7. The spray drying exhaust heat recycling device according to claim 1, characterized in that: The water outlet of the water tank (32) is connected to a circulation pipe (35) through a first pipe (33), and is connected to a water inlet of the second heat exchanger (4) through the circulation pipe (35). A first valve (331) is provided on the first pipe (33).

8. The spray drying exhaust heat recycling device according to claim 7, characterized in that: The second water outlet of the water tank (32) is connected to the circulation pipeline (35) through the second pipeline (34); a branch pipeline is provided on the circulation pipeline (35) and connected to the external discharge pipeline (36); the second pipeline (34) is provided with a third valve (341); the height of the first water outlet of the water tank (32) is higher than the height of the second water outlet; A water pump (352) is provided on the circulation pipeline (35), and a second valve (351) is provided on the circulation pipeline (35) and located between the water tank (31) and the external discharge pipeline (36).

9. The spray drying exhaust heat recycling device according to claim 3, characterized in that: The branch port of the first air duct (8) for connecting the bag dust removal system and the first heat exchange system is connected to the branch port of the chimney (7) via a bypass air duct (9); a first air valve (72) is provided on the chimney (7) between the branch port of the chimney (7) and the water tank (31); a second air valve (91) is provided on the bypass air duct (9); and a third air valve (81) is provided on the first air duct (8) between the branch port of the first air duct (8) and the smoke inlet of the first heat exchange system.

10. The spray drying exhaust heat recycling device according to claim 9, characterized in that: The bag dust removal system comprises a bag dust collector (21) connected to the spray drying system, and a dust detector (22) arranged on the first air duct (8), and the dust detector (22) is located between the branch port of the first air duct (8) and the bag dust collector (21).

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