Lithium iron phosphate positive electrode and negative electrode material roasting waste heat recovery system

Abstract

The utility model discloses a lithium iron phosphate anode and cathode material roasting waste heat recovery system which comprises a heat exchanger, a spray drying tower and a re-combustion furnace communicated with a kiln, the heat exchanger is provided with a flue gas inlet, a first air inlet, a flue gas outlet and an air outlet; the re-combustion furnace is communicated with a flue gas inlet of the heat exchanger through a pipeline; the first air inlet communicates with the outside and is used for introducing external air into the heat exchanger; the spray drying tower is communicated with an air outlet of the heat exchanger through a pipeline; and the flue gas outlet is communicated with an external discharge point through a pipeline. The heat exchanger is additionally arranged between the recombustion furnace and the spray drying tower, heat of smoke generated by the recombustion furnace is exchanged to the spray drying tower for use, part of energy needed by the spray drying tower for heating air is saved, and waste of a large amount of waste heat of the smoke generated by the recombustion furnace is avoided.

Description

Technical Field

[0001] The utility model relates to the technical field of waste heat recovery, in particular to a waste heat recovery system for roasting waste heat of lithium iron phosphate cathode and anode materials. Background Art

[0002] Due to the formulation reasons of lithium iron phosphate cathode and anode materials, tar-like substances will be generated in the flue gas generated by the roasting of both. In order to ensure that the tar-like substances in the flue gas are decomposed as much as possible to meet the emission requirements, it is necessary to use an incinerator to heat it again to 600 - 700 °C by re-combustion. Since the re-combusted flue gas contains too many impurities and cannot be directly contacted with the product for waste heat recovery, generally in the industry, the high-temperature flue gas after heating and re-combustion is mixed with cold air to be reduced to within 150 °C and then directly subjected to backend flue gas treatment or emission, resulting in a large amount of waste heat in the flue gas being wasted. In addition, before the roasting of lithium iron phosphate cathode and anode materials, spray drying treatment is required. During the process, the hot blast stove of the spray drying tower needs to efficiently filter the air before heating the injected air, and the air heated by the hot blast stove is then sent into the spray main tower to dry the powder raw materials of lithium iron phosphate cathode or anode. Among them, the hot blast stove also consumes a large amount of energy for heating the air. Summary of the Invention

[0003] The purpose of the utility model is to overcome the deficiencies of the prior art and provide a waste heat recovery system for roasting waste heat of lithium iron phosphate cathode and anode materials.

[0004] To achieve the above purpose, the technical solution provided by the utility model is as follows:

[0005] A waste heat recovery system for roasting waste heat of lithium iron phosphate cathode and anode materials includes a heat exchanger, a spray drying tower, and a re-combustion furnace connected to a kiln;

[0006] The heat exchanger is provided with a flue gas inlet, a first air inlet, a flue gas outlet, and an air outlet;

[0007] The re-combustion furnace is connected to the flue gas inlet of the heat exchanger through a pipeline;

[0008] The first air inlet is connected to the outside and is used to introduce external air into the heat exchanger;

[0009] The spray drying tower is connected to the air outlet of the heat exchanger through a pipeline;

[0010] The flue gas outlet is connected to an external discharge point through a pipeline.

[0011] In this technical solution, by adding a heat exchanger between the reburning furnace and the spray drying tower, the heat of the flue gas generated by the reburning furnace is exchanged for the use of the spray drying tower, saving part of the energy required for the spray drying tower to heat the air and avoiding waste of a large amount of waste heat of the flue gas generated by the reburning furnace.

[0012] Further, the spray drying tower includes a hot blast stove and a main spray tower;

[0013] The hot blast stove is connected to the heat exchanger through a pipeline, and a spray drying fan, an air fan and a second air inlet communicating with the outside are provided on the connected pipeline;

[0014] The main spray tower is connected to the hot blast stove.

[0015] Further, drying filters are provided at both the first air inlet and the second air inlet, which can not only ensure that the air entering the heat exchanger and the hot blast stove is dry, but also prevent harmful impurities in the outside air (of the plant) from entering the heat exchanger and the hot blast stove.

[0016] Further, the reburning furnace is connected to an external discharge point through a pipeline, and a first control valve is provided on this pipeline; a second control valve is provided on the pipeline connecting the reburning furnace and the heat exchanger;

[0017] The reburning furnace is provided with a third air inlet;

[0018] A third control valve is provided at the third air inlet.

[0019] In this technical solution, when it is necessary to exchange the heat of the flue gas generated by the reburning furnace for the use of the spray drying tower, the second control valve is opened, the first control valve is closed, and the opening degree of the third control valve is adjusted to 10%; when it is not necessary to exchange the heat of the flue gas generated by the reburning furnace for the use of the spray drying tower (i.e., when the flue gas is directly discharged), the second control valve is closed, the first control valve is opened, and the opening degree of the third control valve is adjusted to 100%.

[0020] Further, a first pressure sensor and a second pressure sensor are respectively provided at the flue gas inlet and the flue gas outlet.

[0021] In this technical solution, the pressure of the flue gas inlet and the pressure of the flue gas outlet are respectively detected by the first pressure sensor and the second pressure sensor. If the pressure difference between the flue gas inlet and the flue gas outlet is too large (when the heat exchanger is seriously blocked), the second control valve is closed, the first control valve is opened, and the opening degree of the third control valve is adjusted to 100%, so as to clean the heat exchanger and related pipelines regularly according to the actual situation without affecting normal production.

[0022] Further, a first temperature detection module is provided at the flue gas inlet. When the temperature of the flue gas entering the heat exchanger is detected to be abnormally low by the first temperature detection module (the abnormal operation of the reburning furnace results in a low heating temperature of the flue gas and insufficient combustion), the first control valve opens, the second control valve closes, and the opening degree of the third control valve is adjusted to 100%, so that the flue gas of the reburning furnace is directly discharged to protect the heat exchanger.

[0023] Further, a second temperature detection module is provided at the air outlet. When the temperature of the air at the air outlet is detected to be higher than the set temperature by the second temperature detection module, the frequency of the air blower is increased, so that the amount of air participating in heat exchange increases, and the hot air obtained by heat exchange will decrease until the temperature is lower than the set temperature, thereby avoiding reducing the service life of the air blower due to excessive temperature.

[0024] Further, a third pressure sensor is provided on the pipeline between the second control valve and the reburning furnace, and a flue gas blower is provided on the pipeline between the flue gas outlet and the external discharge point.

[0025] In this technical solution, in order to avoid the suction force of the flue gas blower of the heat exchanger from causing fluctuations in the pressure in the kiln, the pressure on the pipeline between the second control valve and the reburning furnace is monitored by the third pressure sensor. If the pressure is too high, the opening degree of the second control valve is increased; if the pressure is too low, the opening degree of the second control valve is decreased.

[0026] Further, a fourth control valve is provided on the pipeline between the flue gas outlet and the external discharge point to prevent the flue gas from flowing back into the heat exchanger when the flue gas is directly discharged.

[0027] Further, a fifth control valve is provided on the pipeline between the air blower and the spray drying blower to prevent the spray drying blower from sucking unfiltered air into the hot blast stove when the heat exchanger is maintained (such as when replacing the heat exchanger filter element, etc.).

[0028] Compared with the prior art, the principle and advantages of this technical solution are as follows:

[0029] 1. By adding a heat exchanger between the reburning furnace and the spray drying tower, the heat of the flue gas generated by the reburning furnace is exchanged for use by the spray drying tower, saving part of the energy required for the spray drying tower to heat the air and avoiding wasting a large amount of waste heat of the flue gas generated by the reburning furnace.

[0030] 2. When it is necessary to transfer the heat of the flue gas generated by the reburning furnace to the spray drying tower for use, the second control valve is opened, the first control valve is closed, and the opening degree of the third control valve is adjusted to 10%; when it is not necessary to transfer the heat of the flue gas generated by the reburning furnace to the spray drying tower for use (i.e., when the flue gas is directly discharged), the second control valve is closed, the first control valve is opened, and the opening degree of the third control valve is adjusted to 100%; thus, rapid switching between direct flue gas discharge and flue gas heat exchange can be achieved according to specific circumstances.

[0031] 3. When it is necessary to transfer the heat of the flue gas generated by the reburning furnace to the spray drying tower for use, the second control valve is opened, the first control valve is closed, and the opening degree of the third control valve is adjusted to 10%; when it is not necessary to transfer the heat of the flue gas generated by the reburning furnace to the spray drying tower for use (i.e., when the flue gas is directly discharged), the second control valve is closed, the first control valve is opened, and the opening degree of the third control valve is adjusted to 100%.

[0032] 4. When the flue gas temperature entering the heat exchanger is detected to be abnormally low by the first temperature detection module (the flue gas heating temperature is low due to abnormal operation of the reburning furnace and incomplete combustion), the first control valve is opened, the second control valve is closed, and the opening degree of the third control valve is adjusted to 100%, so that the flue gas of the reburning furnace is directly discharged to protect the heat exchanger.

[0033] 5. When the air temperature at the air outlet is detected to be higher than the set temperature by the second temperature detection module, the frequency of the air blower is increased, so that the amount of air participating in heat exchange increases, and the hot air generated by heat exchange will decrease until the temperature is lower than the set temperature, thus avoiding reducing the service life of the air blower due to excessive temperature.

[0034] 6. A fourth control valve is provided on the pipeline between the flue gas outlet and the external discharge point, which can prevent the flue gas from flowing back to the heat exchanger when the flue gas is directly discharged. A fifth control valve is provided on the pipeline between the air blower and the spray drying blower, which can prevent the spray drying blower from extracting unfiltered air into the hot blast stove when the heat exchanger is maintained (such as when replacing the heat exchanger filter element, etc.). Brief Description of the Drawings

[0035] In order to more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the services required in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings in the following description are only some embodiments of the present invention. For those of ordinary skill in the art, other drawings can be obtained based on these drawings without creative efforts.

[0036] Figure 1 It is a schematic structural diagram of a heat recovery system for roasting waste heat of lithium iron phosphate cathode and anode materials of the present invention (including three reburning furnaces).

[0037] Reference Numerals:

[0038] 1 - Heat Exchanger; 2 - Reburning Furnace; 3 - Hot Blast Stove; 4 - Spray Main Tower; 5 - Flue Gas Inlet; 6 - First Air Inlet; 7 - Flue Gas Outlet; 8 - Air Outlet; 9 - External Discharge Point; 10 - Spray Dryer Fan; 11 - Air Fan; 12 - Second Air Inlet; 13 - Dry Filter; 14 - First Control Valve; 15 - Second Control Valve; 16 - Third Air Inlet; 17 - Third Control Valve; 18 - First Pressure Sensor; 19 - Second Pressure Sensor; 20 - First Temperature Detection Module; 21 - Second Temperature Detection Module; 22 - Third Pressure Sensor; 23 - Flue Gas Fan; 24 - Fourth Control Valve; 25 - Fifth Control Valve. Detailed Embodiment

[0039] The present utility model will be further described below in conjunction with the detailed embodiment:

[0040] As Figure 1 shown, a roasting waste heat recovery system for lithium iron phosphate cathode and anode materials according to this embodiment includes a heat exchanger 1, a spray drying tower, and three reburning furnaces 2 communicated with a kiln; the heat exchanger 1 is provided with a flue gas inlet 5, a first air inlet 6, a flue gas outlet 7, and an air outlet 8; the three reburning furnaces 2 are all communicated with the flue gas inlet 5 of the heat exchanger 1 through corresponding pipelines; the first air inlet 6 is communicated with the outside for introducing outside air into the heat exchanger 1; the spray drying tower is communicated with the air outlet 8 of the heat exchanger 1 through a pipeline; the flue gas outlet 7 is communicated with an external discharge point 9 through a pipeline.

[0041] The spray drying tower includes a hot blast stove 3 and a spray main tower 4; the hot blast stove 3 is communicated with the heat exchanger 1 through a pipeline, and a spray dryer fan 10, an air fan 11, and a second air inlet 12 communicated with the outside are provided on the communicated pipeline; the spray main tower 4 is communicated with the hot blast stove 3.

[0042] In this embodiment, by adding a heat exchanger 1 between the reburning furnace 2 and the spray drying tower, the heat of the flue gas generated by the reburning furnace 2 is exchanged for use by the spray drying tower, which can save part of the energy required for the spray drying tower to heat the air and avoid wasting a large amount of waste heat of the flue gas generated by the reburning furnace 2.

[0043] Specifically, in this embodiment, dry filters 13 are provided at both the first air inlet 6 and the second air inlet 12, which can not only ensure that the air entering the heat exchanger 1 and the hot blast stove 3 is dry, but also prevent harmful impurities in the outside air (of the workshop) from entering the heat exchanger 1 and the hot blast stove 3.

[0044] Specifically, in this embodiment, the reburning furnace 2 is connected to an external discharge point 9 through a corresponding pipeline, and a first control valve 14 is provided on each of these pipelines; a second control valve 15 is provided on the pipeline connecting each of the three reburning furnaces 2 to the heat exchanger 1; each of the three reburning furnaces 2 is provided with a third air inlet 16; and a third control valve 17 is provided at the third air inlet 16.

[0045] When it is necessary to transfer the heat of the flue gas generated by the reburning furnace 2 to the spray drying tower for use, the corresponding second control valve 15 is opened, the first control valve 14 is closed, and the opening degree of the third control valve 17 is adjusted to 10%; when it is not necessary to transfer the heat of the flue gas generated by the reburning furnace 2 to the spray drying tower for use (i.e., when the flue gas is directly discharged), the corresponding second control valve 15 is closed, the first control valve 14 is opened, and the opening degree of the third control valve 17 is adjusted to 100%.

[0046] Specifically, in this embodiment, a first pressure sensor 18 and a second pressure sensor 19 are respectively provided at the flue gas inlet 5 and the flue gas outlet 7.

[0047] By using the first pressure sensor 18 and the second pressure sensor 19 to respectively detect the pressure at the flue gas inlet 5 and the pressure at the flue gas outlet 7, if the pressure difference between the flue gas inlet 5 and the flue gas outlet 7 is too large (when the heat exchanger 1 is severely blocked), the second control valve 15 is closed, the first control valve 14 is opened, and the opening degree of the third control valve 17 is adjusted to 100%, so as to regularly clean the heat exchanger 1 and the related pipelines according to the actual situation without affecting normal production.

[0048] Specifically, in this embodiment, a first temperature detection module 20 is provided at the flue gas inlet 5. When it is detected by the first temperature detection module 20 that the temperature of the flue gas entering the heat exchanger 1 is abnormally low (the working of the reburning furnace 2 is abnormal, resulting in low flue gas heating temperature and incomplete combustion), the first control valve 14 is opened, the second control valve 15 is closed, and the opening degree of the third control valve 17 is adjusted to 100%, so that the flue gas of the reburning furnace 2 is directly discharged to protect the heat exchanger 1.

[0049] Specifically, in this embodiment, a second temperature detection module 21 is provided at the air outlet 8. When it is detected by the second temperature detection module 21 that the temperature of the air at the air outlet 8 is higher than the set temperature, the frequency of the air blower 11 is increased, so that the amount of air participating in heat exchange increases, and the hot air obtained by heat exchange will decrease until the temperature is lower than the set temperature, thereby avoiding reducing the service life of the air blower 11 due to excessive temperature.

[0050] In the above, both the first temperature detection module 20 and the second temperature detection module 21 are thermocouples.

[0051] Specifically, in this embodiment, a third pressure sensor 22 is provided on the pipeline between the second control valve 15 and the reburning furnace 2, and a flue gas fan 23 is provided on the pipeline between the flue gas outlet 7 and the external discharge point 9.

[0052] To avoid fluctuations in the pressure inside the kiln caused by the suction of the flue gas fan 23 of the heat exchanger 1, the pressure on the pipeline between the second control valve 15 and the reburning furnace 2 is monitored by the third pressure sensor 22. If the pressure is too high, the opening degree of the second control valve 15 is increased; if the pressure is too low, the opening degree of the second control valve 15 is decreased.

[0053] Specifically, in this embodiment, a fourth control valve 24 is provided on the pipeline between the flue gas outlet 7 and the external discharge point 9 to prevent the flue gas from flowing back into the heat exchanger 1 when the flue gas is directly discharged.

[0054] Specifically, in this embodiment, a fifth control valve 25 is provided on the pipeline between the air fan 11 and the spray drying fan 10 to prevent the spray drying fan 10 from sucking unfiltered air from the heat exchanger 1 into the hot blast stove 3 during the maintenance of the heat exchanger 1 (such as when replacing the filter element of the heat exchanger 1, etc.).

[0055] The above-described embodiments are only the preferred embodiments of the present invention and do not limit the scope of implementation of the present invention. Therefore, all changes made according to the shape and principle of the present invention should be covered within the protection scope of the present invention.

Claims

1. A waste heat recovery system for calcining lithium iron phosphate positive and negative electrode materials, characterized in that: It includes a heat exchanger, a spray drying tower, and a reburning furnace connected to the kiln; The heat exchanger is provided with a smoke inlet, a first air inlet, a smoke outlet, and an air outlet; The reburning furnace is connected to the flue gas inlet of the heat exchanger through a pipeline; The first air inlet is in communication with the outside and is used to introduce external air into the heat exchanger; The spray drying tower is connected to the air outlet of the heat exchanger through a pipeline; The smoke outlet is communicated with an external discharge point through a pipeline.

2. A lithium iron phosphate positive and negative electrode material calcination waste heat recovery system according to claim 1, characterized in that: The spray drying tower comprises a hot air furnace and a spray main tower; The hot air furnace is connected to the heat exchanger through a pipeline, and the connected pipeline is provided with a spray drying fan, an air fan and a second air inlet connected to the outside; The main spray tower is communicated with the hot blast furnace.

3. A lithium iron phosphate positive and negative electrode material calcination waste heat recovery system according to claim 2, characterized in that: Dry filters are provided at the first air inlet and the second air inlet.

4. A lithium iron phosphate positive and negative electrode material calcination waste heat recovery system according to claim 1, characterized in that: The reburning furnace is connected to an external discharge point through a pipeline, and a first control valve is provided on the pipeline; a second control valve is provided on the pipeline connecting the reburning furnace and the heat exchanger; The reburning furnace is provided with a third air inlet; A third control valve is provided at the third air inlet.

5. A lithium iron phosphate positive and negative electrode material calcination waste heat recovery system according to claim 4, characterized in that: The smoke inlet and the smoke outlet are respectively provided with a first pressure sensor and a second pressure sensor.

6. A lithium iron phosphate positive and negative electrode material calcination waste heat recovery system according to claim 4, characterized in that: The smoke inlet is provided with a first temperature detection module.

7. A lithium iron phosphate positive and negative electrode material calcination waste heat recovery system according to claim 2, characterized in that: A second temperature detection module is provided at the air outlet.

8. A lithium iron phosphate positive and negative electrode material calcination waste heat recovery system according to claim 4, characterized in that: A third pressure sensor is provided on the pipeline between the second control valve and the reburning furnace, and a flue gas fan is provided on the pipeline between the flue gas outlet and the external discharge point.

9. A lithium iron phosphate positive and negative electrode material calcination waste heat recovery system according to claim 8, characterized in that: A fourth control valve is provided on the pipeline between the smoke outlet and the external discharge point.

10. A lithium iron phosphate positive electrode and negative electrode material calcination waste heat recovery system according to claim 2, characterized in that: A fifth control valve is provided on the pipeline between the air blower and the spray drying blower.

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