Lithium battery material sintering rotary kiln waste heat recycling system and method capable of reducing carbon

Abstract

The present application relates to the technical field of waste heat recycling and treatment, and discloses a lithium battery material sintering rotary kiln waste heat recycling system and method capable of reducing carbon. The system comprises a first waste heat recycling device, a second waste heat recycling device, and a third waste heat recycling device. The first waste heat recycling device comprises a first evaporator, a first steam turbine generator and a first booster pump which are circularly communicated with one another, and the first booster pump is used for conveying a first working medium to circularly flow in the first evaporator, the first steam turbine generator and the first booster pump; the second waste heat recycling device comprises a second evaporator, a second steam turbine generator and a second booster pump which are circularly communicated with one another, and the second booster pump is used for conveying a second working medium to circularly flow in the second evaporator, the second steam turbine generator and the second booster pump; and the third waste heat recycling device comprises a heat exchanger; fume generated by the rotary kiln sequentially flows through the first evaporator, the second evaporator and the heat exchanger through pipes. According to the waste heat recycling system and method of the present application, the waste heat recycling efficiency is high, and the carbon reduction effect is good.

Description

A carbon-reducing lithium battery material sintering rotary kiln waste heat recovery system and method Technical Field

[0001] The present application relates to the field of waste heat recovery technology, and in particular to a waste heat recovery system and method for a sintering rotary kiln for lithium battery materials capable of reducing carbon. Background Art

[0002] Lithium-ion batteries are enjoying widespread adoption as a clean energy storage method, but the production of lithium battery materials is plagued by high energy consumption. Rotary kilns are used for drying lithium-ion battery precursors and sintering cathode materials. Their high energy consumption hinders energy conservation and emission reduction efforts. Currently, waste heat recovery in rotary kilns primarily involves collecting waste heat from the flue gas within the kiln and exchanging it with an evaporator. However, since the evaporator's maximum heat exchange efficiency is within a relatively high temperature range, the heat from the relatively low-temperature flue gas cannot be effectively recovered, resulting in low waste heat recovery efficiency, an inability to further reduce production power consumption, and limited carbon reduction efforts.

[0003] Summary of the Invention

[0004] The purpose of this application is to provide a waste heat recovery system and method for a lithium battery material sintering rotary kiln that can reduce carbon, so that the waste heat recovery efficiency is high and the carbon reduction effect is good.

[0005] To achieve the above objectives, the present application provides a waste heat recovery system for a rotary kiln for sintering lithium battery materials capable of reducing carbon emissions, comprising:

[0006] A first waste heat recovery device includes a first evaporator, a first steam turbine generator, and a first booster pump that are in cyclic communication with each other, wherein the first booster pump is used to convey a first working medium to circulate within the first evaporator, the first steam turbine generator, and the first booster pump;

[0007] a second waste heat recovery device comprising a second evaporator, a second steam turbine generator, and a second booster pump in a cyclic connection, wherein the second booster pump is used to convey a second working medium to circulate in the second evaporator, the second steam turbine generator, and the second booster pump; and

[0008] A third waste heat recovery device includes a heat exchanger;

[0009] The flue gas generated by the rotary kiln flows sequentially through the first evaporator, the second evaporator and the heat exchanger through a pipeline, and the heat exchanger is used to preheat the material in the rotary kiln.

[0010] In some embodiments, the first working fluid is water.

[0011] In some embodiments, the second working fluid is one of propane, n-butane, isobutane and ethyl chloride.

[0012] In some embodiments, the first waste heat recovery device further includes a first condenser, and the first steam turbine generator and the first booster pump are connected through the first condenser.

[0013] In some embodiments, the second waste heat recovery device further includes a second condenser, and the second steam turbine generator and the second booster pump are connected via the second condenser.

[0014] On the other hand, the present application provides a method for recovering waste heat from a rotary kiln for sintering lithium battery materials with carbon reduction, comprising:

[0015] The first evaporator, the second evaporator and the heat exchanger are turned on, and the flue gas generated by the rotary kiln flows through the first evaporator, the second evaporator and the heat exchanger in sequence to be heated;

[0016] The first steam turbine generator is turned on, and the first working fluid in the first evaporator is heated to generate first high-pressure gas that drives the first steam turbine generator to generate electricity. The first steam turbine generator discharges first low-pressure gas, and the first booster pump is turned on to transport the first low-pressure gas from the first steam turbine generator to the first evaporator.

[0017] The second steam turbine generator is started, and the second working fluid in the second evaporator is heated to generate a second high-pressure gas that drives the second steam turbine generator to generate electricity. The second steam turbine generator discharges a second low-pressure gas, and the second booster pump is started to transport the second low-pressure gas from the second steam turbine generator to the second evaporator.

[0018] The material is moved to the heat exchanger for preheating, and after the preheating is completed, the material is moved to the rotary kiln for sintering.

[0019] In some embodiments, the first high-pressure gas and the first low-pressure gas are water vapor.

[0020] In some embodiments, the second high-pressure gas and the second low-pressure gas are one of propane, n-butane, isobutane and ethyl chloride.

[0021] In some embodiments, the first low-pressure gas discharged from the first steam turbine generator is condensed into a first liquid through a first condenser, and the first booster pump is turned on to transport the first liquid to the first evaporator.

[0022] In some embodiments, the second low-pressure gas discharged from the second turbine generator is condensed into a second liquid through a second condenser, and the second booster pump is turned on to transport the second liquid to the first evaporator.

[0023] This application provides a waste heat recovery system for a lithium battery material sintering rotary kiln capable of reducing carbon emissions. Compared with the prior art, its beneficial effects are:

[0024] The first waste heat recovery device can recover waste heat from flue gas with higher temperature and convert it into electrical energy. The second waste heat recovery device can recover waste heat from flue gas with lower temperature that has passed through the first waste heat recovery device and convert it into electrical energy. The third waste heat recovery device can recover waste heat from low-temperature flue gas that has passed through the second waste heat recovery device and preheat the material. Therefore, the waste heat recovery efficiency is high and the carbon reduction effect is good. BRIEF DESCRIPTION OF THE DRAWINGS

[0025] FIG1 is a schematic diagram of the principle structure of a waste heat recovery system for sintering rotary kiln of lithium battery materials with carbon reduction provided in an embodiment of the present application.

[0026] In the figure: 1. first evaporator; 2. first steam turbine generator; 3. first booster pump; 4. second evaporator; 5. second steam turbine generator; 6. second booster pump; 7. heat exchanger; 8. rotary kiln; 9. first condenser; 10. second condenser. DETAILED DESCRIPTION

[0027] The technical solutions in the embodiments of the present application will be clearly and completely described below in conjunction with the drawings in the embodiments of the present application. Obviously, the described embodiments are only part of the embodiments of the present application, rather than all the embodiments.

[0028] It should be understood that in the description of this application, the terms "upper", "lower", "vertical", "horizontal", "top", "bottom", "inside", "outside", etc. indicate orientations or positional relationships based on the orientations or positional relationships shown in the accompanying drawings, and are only for the convenience of describing this application and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore cannot be understood as a limitation on this application. The terms "first" and "second" are used for descriptive purposes only and cannot be understood as indicating or implying relative importance or implicitly indicating the number of technical features indicated, that is, the features defined as "first" and "second" may explicitly or implicitly include one or more of the features. In addition, unless otherwise specified, "multiple" means two or more.

[0029] In addition, the technical features involved in the different embodiments of the present application described below can be combined with each other as long as they do not conflict with each other.

[0030] As shown in Figure 1, a waste heat recovery system for a sintering rotary kiln for lithium battery materials with carbon reduction provided by one embodiment of the present application includes a first waste heat recovery device, a second waste heat recovery device, and a third waste heat recovery device. The first waste heat recovery device includes a first evaporator 1, a first steam turbine generator 2, and a first booster pump 3 in a circular connection, and the first booster pump 3 is used to convey a first working medium to circulate in the first evaporator 1, the first steam turbine generator 2, and the first booster pump 3; the second waste heat recovery device includes a second evaporator 4, a second steam turbine generator 5, and a second booster pump 6 in a circular connection, and the second booster pump 6 is used to convey a second working medium to circulate in the second evaporator 4, the second steam turbine generator 5, and the second booster pump 6; the third waste heat recovery device includes a heat exchanger 7.

[0031] During operation, the flue gas generated by the rotary kiln 8 flows through the first evaporator 1, the second evaporator 4 and the heat exchanger 7 in sequence through the pipeline. It should be noted that the flue gas pipeline of the rotary kiln 8 includes the first section, the second section and the third section in sequence. When the flue gas with a higher temperature heats the first evaporator 1, it generates high-pressure gas to drive the first steam turbine generator 2 to generate electricity, realizing the heat recovery of the first section; when the flue gas with a medium temperature heats the second evaporator 4, it generates high-pressure gas to drive the second steam turbine generator 5 to generate electricity, realizing the heat recovery of the second section; when the flue gas with a lower temperature heats the heat exchanger 7, the heat exchanger has heat to preheat the material of the rotary kiln 8, realizing the heat recovery of the third section, which can reduce the heat load of the rotary kiln 8 and make the material sintering efficiency higher.

[0032] Based on the above settings, the waste heat recovery efficiency is high and the carbon reduction effect is good.

[0033] In one embodiment, the first working fluid is water. During the exhaust process of the rotary kiln 8, the flue gas initially has a relatively high temperature of 900°C to 1000°C. After passing through the first evaporator 1, the water in the first evaporator 1 is rapidly vaporized to form first high-pressure steam. This first high-pressure steam drives the first steam turbine generator 2 to generate electricity, converting thermal energy into electrical energy and achieving energy recovery.

[0034] In one embodiment, the second working fluid is one of propane, n-butane, isobutane, and ethyl chloride. The flue gas temperature of the rotary kiln 8 decreases after passing through the first evaporator 1. When passing through the second evaporator 4, one of the propane, n-butane, isobutane, and ethyl chloride is heated to form a second high-pressure steam. The second high-pressure steam drives the second steam turbine generator 5 to generate electricity, converting thermal energy into electrical energy, thereby realizing energy recovery. It should be noted that since the boiling points of propane, n-butane, isobutane, and ethyl chloride are all lower than those of water, the first evaporator 1 can still maintain a high heat exchange efficiency in the face of the relatively low flue gas of the rotary kiln 8, thereby achieving high waste heat recovery efficiency.

[0035] In one embodiment, the first waste heat recovery device further includes a first condenser 9, through which the first steam turbine generator 2 and the first booster pump 3 are connected. The first condenser 9 can reduce the temperature of the gas exhausted from the first steam turbine generator 2, thereby reducing the pressure of the gas, thereby alleviating the pressure exerted by the gas on the delivery pipeline.

[0036] In one embodiment, the second waste heat recovery device further includes a second condenser 10, through which the second steam turbine generator 5 and the second booster pump 6 are connected. The second condenser 10 can reduce the temperature of the gas exhausted from the second steam turbine generator 4, thereby reducing the pressure of the gas, thereby alleviating the pressure exerted by the gas on the delivery pipeline.

[0037] As shown in FIG1 , another embodiment of the present application provides a method for recovering waste heat from a rotary kiln for sintering lithium battery materials with carbon reduction, comprising:

[0038] Step 1: Start the first evaporator 1, the second evaporator 4 and the heat exchanger 7. The flue gas generated by the rotary kiln 8 flows through the first evaporator 1, the second evaporator 4 and the heat exchanger 7 in sequence to be heated.

[0039] Step 2: Start the first steam turbine generator 2. The first working fluid in the first evaporator 1 is heated to generate first high-pressure gas, which drives the first steam turbine generator 2 to generate electricity. The first steam turbine generator 2 discharges first low-pressure gas. The first booster pump 3 is started to transport the first low-pressure gas from the first steam turbine generator 2 to the first evaporator 1.

[0040] Step 3: Start the second steam turbine generator 5. The second working fluid in the second evaporator 4 is heated to generate second high-pressure gas, which drives the second steam turbine generator 5 to generate electricity. The second steam turbine generator 5 discharges the second low-pressure gas. The second booster pump 6 is started to transport the second low-pressure gas from the second steam turbine generator 5 to the second evaporator 4.

[0041] Step 4: Move the material to the heat exchanger 7 for preheating. After the preheating is completed, move the material to the rotary kiln 8 for sintering.

[0042] Through the above method, the waste heat of the flue gas generated by the rotary kiln 8 can be recovered in sequence by the first evaporator 1, the second evaporator 4 and the heat exchanger 7, so that the waste heat recovery efficiency is high and the production power consumption is reduced.

[0043] In another embodiment, the first high-pressure gas and the first low-pressure gas are water vapor, and the water vapor performs work on the first steam turbine generator 2 to generate electricity.

[0044] In another embodiment, the second high-pressure gas and the second low-pressure gas are one of propane, n-butane, isobutane and ethyl chloride. The gases are heated to generate power for the second turbine generator 5.

[0045] In another embodiment, the first low-pressure gas discharged from the first steam turbine generator 2 is condensed into a first liquid through the first condenser 9, and the first booster pump 3 is turned on to deliver the first liquid to the first evaporator 1. By forming the first liquid, the delivery efficiency of the first booster pump 3 is improved.

[0046] In another embodiment, the second low-pressure gas discharged from the second turbine generator 5 is condensed into a second liquid through the second condenser 10, and the second booster pump 6 is turned on to deliver the second liquid to the first evaporator 4. By forming the second liquid, the delivery efficiency of the second booster pump 6 is improved.

[0047] Regarding the waste heat recovery system and method for the sintering rotary kiln of lithium battery materials capable of reducing carbon in the above embodiment, the proportion of waste heat from the flue gas in the rotary kiln is specifically analyzed.

[0048] A heat balance analysis was conducted on the rotary kiln, and the process was simulated using ASPEN HYSYS process simulation software. Based on the first law of thermodynamics, a thermodynamic analysis of the rotary kiln was conducted, with 0°C as the benchmark. The heat flowing into the rotary kiln mainly comes from the heat Q1 brought in by the sintering box, the heat Q2 produced by the heating elements of the rotary kiln, and the heat Q3 brought in by the air. The heat flowing out of the rotary kiln includes the heat Q4 brought out by the sintering box, the heat Q5 required to evaporate the product water vapor, the heat Q6 brought out by the exhaust gas, and the heat Q7 lost by the kiln itself. According to experience, other heat losses Q8 take 5% of the total input heat. Therefore, the following equation is obtained based on the heat balance equation: Q1+Q2+Q3=Q4+Q5+Q6+Q7+Q8

[0049] To accurately simulate the system flow in actual production, the following assumptions were made: uniform material distribution, a sintering box and material inlet temperature of 25°C, and a rotary kiln firing cycle of 1800 minutes. The flue gas temperature was 950°C, the kiln outer surface temperature was 120°C, the kiln outer surface emissivity was 0.85, and the rotary kiln firing cycle was approximately 3 hours.

[0050] Calculations show that the maximum heat content of rotary kiln flue gas is approximately 33%. Therefore, recovering waste heat from rotary kiln flue gas plays a significant role in reducing its energy consumption. Exhaust flue gas temperatures are approximately 900-1000°C, with a high thermal energy quality. Therefore, recovering waste heat from flue gas is highly valuable, and fully utilizing it can achieve carbon reduction benefits.

[0051] The above is only a preferred embodiment of the present application. It should be pointed out that for ordinary technicians in this technical field, several improvements and replacements can be made without departing from the technical principles of the present application. These improvements and replacements should also be regarded as the scope of protection of the present application.

Claims

1. A waste heat recovery system for sintering rotary kiln of lithium battery materials capable of reducing carbon, characterized in that: include: A first waste heat recovery device comprises a first evaporator (1), a first steam turbine generator (2) and a first booster pump (3) which are cyclically connected, wherein the first booster pump (3) is used to transport a first working fluid to circulate in the first evaporator (1), the first steam turbine generator (2) and the first booster pump (3); A second waste heat recovery device comprises a second evaporator (4), a second steam turbine generator (5) and a second booster pump (6) which are cyclically connected, wherein the second booster pump (6) is used to convey a second working fluid to circulate in the second evaporator (4), the second steam turbine generator (5) and the second booster pump (6); and A third waste heat recovery device comprises a heat exchanger (7); The flue gas generated by the rotary kiln (8) flows sequentially through the first evaporator (1), the second evaporator (4) and the heat exchanger (7) through a pipeline, and the heat exchanger (7) is used to preheat the material in the rotary kiln (8).

2. The waste heat recovery system for sintering rotary kiln of lithium battery materials capable of reducing carbon according to claim 1 is characterized in that: The first working fluid is water.

3. The waste heat recovery system for sintering rotary kiln of lithium battery materials capable of reducing carbon according to claim 1 is characterized in that: The second working fluid is one of propane, n-butane, isobutane and ethyl chloride.

4. The waste heat recovery system for sintering rotary kiln of lithium battery materials capable of reducing carbon according to claim 1, characterized in that: The first waste heat recovery device further comprises a first condenser (9), and the first steam turbine generator (2) and the first booster pump (3) are connected via the first condenser (9).

5. The waste heat recovery system for sintering rotary kiln of lithium battery materials capable of reducing carbon according to claim 1, characterized in that: The second waste heat recovery device further comprises a second condenser (10), and the second steam turbine generator (5) and the second booster pump (6) are connected via the second condenser (10).

6. A method for recovering waste heat from a rotary kiln for sintering lithium battery materials capable of reducing carbon, characterized in that: include: The first evaporator (1), the second evaporator (4) and the heat exchanger (7) are turned on, and the flue gas generated by the rotary kiln (8) flows through the first evaporator (1), the second evaporator (4) and the heat exchanger (7) in sequence to be heated; The first steam turbine generator (2) is turned on, and the first working fluid in the first evaporator (1) is heated to generate a first high-pressure gas to drive the first steam turbine generator (2) to generate electricity, the first steam turbine generator (2) discharges a first low-pressure gas, and the first booster pump (3) is turned on to transport the first low-pressure gas from the first steam turbine generator (2) to the first evaporator (1); The second steam turbine generator (5) is turned on, and the second high-pressure gas generated by the second working fluid in the second evaporator (4) is driven by the second steam turbine generator (5) to generate electricity. The second steam turbine generator (5) discharges the second low-pressure gas, and the second booster pump (6) is turned on to transport the second low-pressure gas from the second steam turbine generator (5) to the second evaporator (4); The material is moved to the heat exchanger (7) for preheating, and after the preheating is completed, the material is moved to the rotary kiln (8) for sintering.

7. The method for recovering waste heat from a rotary kiln for sintering lithium battery materials capable of reducing carbon emissions according to claim 6, characterized in that: The first high-pressure gas and the first low-pressure gas are water vapor.

8. The method for recovering waste heat from a rotary kiln for sintering lithium battery materials capable of reducing carbon emissions according to claim 6, characterized in that: The second high-pressure gas and the second low-pressure gas are one of propane, n-butane, isobutane and ethyl chloride.

9. The method for recovering waste heat from a rotary kiln for sintering lithium battery materials capable of reducing carbon according to claim 6, characterized in that: The first low-pressure gas discharged from the first steam turbine generator (2) is condensed into a first liquid through a first condenser (9), and the first booster pump (3) is turned on to transport the first liquid to the first evaporator (1).

10. The method for recovering waste heat from a rotary kiln for sintering lithium battery materials capable of reducing carbon emissions according to claim 6, characterized in that: The second steam turbine generator (5) discharges the second low-pressure gas, which passes through the second condenser (10) to condense the second liquid, and then starts the second booster pump (6) to transport the second liquid to the first evaporator (4).

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