Biomass gasification system and method for coating, granulating and heating battery negative electrode material

Abstract

The invention relates to the technical field of battery negative electrode material processing, in particular to a biomass gasification system and method for battery negative electrode material coating granulation heating, and the biomass gasification system comprises a biomass gasification subsystem, a petroleum coke coating granulation heating subsystem, a waste gas combustion treatment subsystem and a waste heat utilization subsystem, the biomass gasification subsystem comprises a biomass raw material drying device, a biomass feeding system, a biomass gasification furnace, a biomass gas purification device, a water-cooling charcoal discharging device and a fuel gas booster fan which are connected in sequence. According to the biomass gasification system and method for coating, granulating and heating the battery negative electrode material, the heating cost can be saved by 20% or above, meanwhile, the quality of petroleum coke products is not affected, petroleum coke waste gas is recycled, the dust conveying capacity is improved, the problem of ash and tar deposition caused by too low waste gas flow speed is solved, and the energy consumption is reduced. And a nitrogen constant pressure system is upgraded and reformed, so that the risk of burning explosion of waste gas can be further reduced.

Description

Technical Field

[0001] This invention relates to the field of battery anode material processing technology, specifically to a biomass gasification system and method for heating and coating battery anode materials. Background Technology

[0002] The core principle of the granulation and coating process for battery anode materials is to form a uniform coating layer on the surface of particles through physical or chemical methods to improve the material's conductivity, structural stability, and electrochemical performance. Physical coating methods involve mechanically mixing the substrate with coating materials such as asphalt, resin, and graphene, followed by high-temperature carbonization to complete the coating. This eliminates the need for complex reaction conditions or high-purity raw materials, significantly reducing equipment investment and production costs. Currently, the cost of using electric jacket heating in granulation and coating processes is very high, far exceeding the cost of heating with natural gas. Using natural gas heating is also costly, produces a certain amount of carbon dioxide emissions, and relies on natural gas pipeline connections. Furthermore, existing natural gas heating methods cannot achieve the same ±1℃ temperature control precision as electric jacket heating, making it difficult to control the volatile matter content of petroleum coke after granulation and coating, affecting the product quality of petroleum coke. The waste gas generated during the granulation and coating process contains asphalt and petroleum coke dust. On the one hand, the large amount of combustible components contained in the material is not fully utilized, and on the other hand, it greatly increases the cost of subsequent waste gas environmental treatment. The main heating methods include continuous rotary kiln and tunnel kiln heating. Among them, the continuous rotary kiln process has gradually become the mainstream heating method in the market due to its lower energy consumption and operating costs. The continuous rotary kiln mainly uses electric jacket heating, which has the advantages of high temperature control accuracy, but suffers from the disadvantage of high electric heating costs. With the increasing competition in the battery anode material market, it is necessary to choose a new heating process to reduce enterprise costs. To solve the above problems, we have made improvements and proposed a biomass gasification system and method for heating the coating and granulation of battery anode materials. Summary of the Invention

[0003] To solve the above-mentioned technical problems, the present invention provides the following technical solution: This invention provides a biomass gasification system for heating and coating of battery negative electrode materials, comprising a biomass gasification subsystem, a petroleum coke coating and granulation heating subsystem, a waste gas combustion treatment subsystem, and a waste heat utilization subsystem. The biomass gasification subsystem includes a biomass raw material drying device, a biomass feeding system, a biomass gasifier, a biomass gas purification device, a water-cooled char output device, and a gas-fired booster fan connected in sequence. The output end of the water-cooled char output device is connected to a coke powder preparation system, and the output end of the gas-fired booster fan is connected to a burner. The petroleum coke coating granulation heating subsystem includes a mechanical mill, a batch mixer, a tubular chain conveyor, a continuous granulation reactor, a cooling reactor, and a shaping machine connected in sequence. The continuous granulation reactor is filled with protective nitrogen gas, and the output end of the shaping machine is connected to a cyclone separator. The waste gas combustion treatment subsystem includes a burner, an SCR denitrification reactor, and a bag filter. The waste gas outlet of the continuous granulation reactor is connected to the burner through a pipeline, and the output end of the bag filter is connected to an induced draft fan and an exhaust stack. The waste heat utilization subsystem includes a gas-to-gas heat exchanger, which is connected to the combustion air duct of the burner, the flue gas outlet duct of the SCR denitrification reactor, and the nitrogen delivery duct.

[0004] As a preferred embodiment of the present invention, the continuous granulation reactor includes a high-temperature reactor and a low-temperature reactor, which are separated by an annular baffle. The outer wall of the baffle is welded and the inner wall is reserved with a thermal expansion gap. Both the high-temperature reactor and the low-temperature reactor are equipped with flue gas regulating valves, namely valves 7-10, for regulating the flue gas volume and flue gas pressure inside the reactor.

[0005] As a preferred embodiment of the present invention, the nitrogen system includes a nitrogen constant pressure-transport-purging unit. The pipeline pressure of the nitrogen constant pressure-transport-purging unit is maintained at around 20 kPa, and nitrogen purging points are set at the bends and equipment interfaces of the waste gas transport pipeline. The purging direction is consistent with the airflow direction. The nitrogen transport pipeline is first connected to the gas-to-gas heat exchanger for preheating nitrogen. The gas-to-gas heat exchanger adopts a two-stage heat exchange structure. The first stage is used for heat exchange between the flue gas and nitrogen after SCR denitrification, and the second stage is used for heat exchange between the flue gas and combustion air after the first stage heat exchange. The regulating valve group of the burner includes valve 1, which is the biomass gas inlet valve, valve 2, which is the biomass gas supplementary heat valve, valve 3, which is the biomass gas main valve, valve 4, which is the waste gas supplementary heat valve, valve 5, which is the waste gas inlet valve, and valve 6, which is the waste gas supplementary heat auxiliary valve.

[0006] A method for heating and coating of battery negative electrode material using a biomass gasification system includes the following steps: S1. Biomass pretreatment and gasification; S2. Biomass gas heating during system startup; S3. Exhaust gas replacement and temperature compensation; S4. Nitrogen System Control and Pipeline Purging S5. Two-stage heat exchange for waste heat utilization; S6. Coating granulation and finished product preparation.

[0007] As a preferred technical solution of the present invention, in step S1, the biomass raw material is dried by a biomass raw material drying device and then fed into a biomass gasifier through a biomass feeding system. The raw material is gasified in the gasifier to produce biochar, biogas and biotar. The biochar is fed into a coke powder preparation system through a water-cooled char discharge device. The biogas and biotar are transported to the burner by a gas booster fan after most of the dust and tar are removed by a biogas purification device.

[0008] As a preferred technical solution of the present invention, S2 is to start the biomass gasification subsystem in advance, open valves 1 and 3 of the burner, so that the biomass gas is mixed and burned with the combustion air preheated by the gas-to-gas heat exchanger in the burner; the high-temperature flue gas generated by combustion is first introduced into the high-temperature reactor to maintain the temperature of petroleum coke in the high-temperature reactor at 550~600℃, and then introduced into the low-temperature reactor to maintain the flue gas temperature in the low-temperature reactor at 300~400℃; the flue gas volume and flue gas pressure in the reactor are adjusted by valves 7-10, and at the same time, the petroleum coke is mechanically ground to 5~20μm and then mixed with the metered asphalt powder in the batch mixer, and then sent into the low-temperature reactor of the continuous granulation reactor by the tubular chain conveyor.

[0009] As a preferred embodiment of the present invention, the material in the S3 low-temperature reactor is stirred at 300~400℃ for 2 hours and then conveyed to the high-temperature reactor via a screw conveyor; the high-temperature reactor contains waste gas generated by the high-temperature decomposition of petroleum coke, which contains nitrogen, VOCs, tar, carbon powder, and oxygen, and the flow rate of the waste gas satisfies Formula 1: V exhaust gas = V nitrogen + VVOCs Vexhaust gas is the total exhaust gas flow rate, Vnitrogen is the nitrogen volumetric flow rate, and VVOCs is the VOCs volumetric flow rate, both in m³ / h. The waste gas is delivered to the burner under its own pressure. Valve 5 is gradually opened and the opening of valve 3 is reduced, so that the waste gas gradually replaces the biomass gas as fuel. If the temperature of the low-temperature reactor is not sufficiently heated by the flue gas discharged from the high-temperature reactor, valves 2, 6 or 4 are opened to supplement the heat by burning biomass gas or waste gas to ensure that the temperature of the low-temperature reactor meets the standard.

[0010] As a preferred embodiment of the present invention, in step S4, the nitrogen pressure-conveying-purging unit is adjusted to increase the pressure inside the high-temperature reactor to 20 kPa, and the nitrogen pressure satisfies formula 3: Pnitrogen = 1.2 × (Pexhaust gas resistance + Pgas pressure) Pnitrogen is the nitrogen pressure; Pexhaust gas resistance is the exhaust gas delivery pipeline resistance; Pgas pressure is the gas pressure required by the burner; all units are kPa. Nitrogen flow rate satisfies formula 4: V'nitrogen = 1.33 × Vnitrogen V' nitrogen is the nitrogen volumetric flow rate after modification, and V nitrogen is the nitrogen volumetric flow rate before modification. The units are both m³ / h. The oxygen content in the exhaust gas satisfies Formula 5: V'oxygen = 0.91 × Voxygen V'oxygen is the volumetric flow rate of oxygen in the exhaust gas after the modification, and Voxygen is the volumetric flow rate of oxygen in the exhaust gas before the modification. The units are both m³ / h. When the obstruction in the exhaust gas delivery pipeline increases significantly, open the nitrogen purging points at the pipeline bends and equipment interfaces, and purge the pipeline in the direction of airflow.

[0011] As a preferred embodiment of the present invention, in the first stage of heat exchange in S5: the 300°C flue gas from the SCR denitrification outlet enters the gas-to-gas heat exchanger to heat the nitrogen gas, raising its temperature from 20°C to 200°C, satisfying formula 6: 0.98 × V_flue gas × CV (flue gas) × (T_flue gas - T'_flue gas) = ​​V_nitrogen × CV (nitrogen) × (200 - 20) Vflue gas is the flue gas volumetric flow rate, in m³ / h; CV (flue gas) and CV (nitrogen) are the isochoric specific heats of flue gas and nitrogen, respectively, in kJ / (kg·℃); Tflue gas is the flue gas temperature before heat exchange, in ℃; T'flue gas is the flue gas temperature after the first stage of heat exchange, in ℃; the heat exchange efficiency is calculated as 98%. Second-stage heat exchange: The flue gas after the first-stage heat exchange continues to heat the combustion air in the gas-to-gas heat exchanger, raising the combustion air temperature from 20℃ to 250℃, satisfying Formula 7: 0.98 × Vflue gas × CV (flue gas) × (T'flue gas - T"flue gas) = Vair × CV (air) × (250 - 20) Vair is the volumetric flow rate of the combustion air, in m³ / h; CVair is the specific heat at constant volume of the combustion air, in kJ / (kg·℃); T"flue gas is the flue gas temperature after the second-stage heat exchange, in ℃. After heat exchange, the flue gas is successively treated by SCR denitrification and bag filter dust collector, and then sent to the exhaust stack by induced draft fan to meet emission standards.

[0012] As a preferred embodiment of the present invention, after the petroleum coke in the high-temperature reactor in S6 is coated and granulated at 550~600℃, it is sent to a cooling reactor to be cooled to below 60℃; the cooled material is processed by a shaping machine (crushed and trimmed by high-speed rotating blades) to obtain particles with a particle size of 8~18μm; the outlet diameter D (mm) of the waste gas conveying pipeline satisfies the waste gas velocity V=10m / s, and the velocity calculation formula is 2: V = 4 × Vexhaust gas / (3600 × Π × D2); After shaping, the particles are separated, collected, and packaged in a cyclone separator to obtain the finished battery anode material. Carbon powder emission loss is reduced by more than 50%, and petroleum coke production capacity is increased by more than 1%.

[0013] The beneficial effects of this invention are as follows: Compared with existing electric heating solutions, this biomass gasification system and method for coating and granulating battery negative electrode materials has the following advantages: (1) It can save more than 20% of heating costs without affecting the quality of petroleum coke products; (2) The waste gas from petroleum coke is recycled and reused. At the same time, the flow rate at the outlet is set. By increasing the flow rate, the dust conveying capacity is increased, and the problem of ash and tar deposition caused by excessively low waste gas flow rate is reduced. It is preliminarily estimated that carbon emission loss can be reduced by more than 50% and petroleum coke production capacity can be increased by more than 1%. (3) Upgrading the nitrogen pressure regulating system further reduces the oxygen content in the exhaust gas by 9%, which can further reduce the risk of exhaust gas combustion and explosion. At the same time, adding a nitrogen purging system greatly reduces labor costs and avoids the risk of combustion and explosion caused by increased oxygen content due to manual ash removal. In addition, by coupling the nitrogen system with the flue gas waste heat utilization system, the nitrogen temperature is increased, which can avoid the deposition of asphalt ash due to the decrease in exhaust gas temperature caused by nitrogen entering. This reduces the exhaust gas temperature and the amount of fuel gas consumed. (4) Set up a segmented flue gas heating process and two gas heating regulation systems to ensure the uniformity and stability of heating; set up a two-stage heat exchange system for waste heat utilization at the SCR outlet to use the waste heat of flue gas to heat nitrogen and combustion air, thereby reducing the gas consumption by lowering the exhaust temperature. Attached Figure Description

[0014] The accompanying drawings are provided to further illustrate the invention and form part of the specification. They are used in conjunction with embodiments of the invention to explain the invention and do not constitute a limitation thereof. In the drawings: Figure 1 This is a diagram showing the composition of the biomass gasification-anode material granulation and coating process coupling system of the biomass gasification system and method for heating and coating of battery anode materials according to the present invention. Figure 2 This is a flowchart of the optimized and energy-saving process of the coating granulation of a biomass gasification system and method for heating battery negative electrode material coating according to the present invention. Figure 3 This is a detailed process diagram of the high-temperature autoclave for coating and granulation of a biomass gasification system and method for heating and coating of battery negative electrode materials according to the present invention. Figure 4 This is a schematic diagram of the flue gas flow direction in the coating granulation kettle of a biomass gasification system and method for heating and coating of battery negative electrode materials according to the present invention. Detailed Implementation

[0015] The preferred embodiments of the present invention will be described below with reference to the accompanying drawings. It should be understood that the preferred embodiments described herein are for illustration and explanation only and are not intended to limit the present invention.

[0016] like Figures 1-4 As shown, a biomass gasification system for heating and coating granulation of battery negative electrode materials includes a biomass gasification subsystem, a petroleum coke coating granulation heating subsystem, a waste gas combustion treatment subsystem, and a waste heat utilization subsystem. The biomass gasification subsystem includes a biomass raw material drying device, a biomass feeding system, a biomass gasifier, a biomass gas purification device, a water-cooled char output device, and a gas booster fan connected in sequence. The output end of the water-cooled char output device is connected to the coke powder preparation system, and the output end of the gas booster fan is connected to the burner. The petroleum coke coating granulation heating subsystem includes a mechanical mill, a batch mixer, a tubular chain conveyor, a continuous granulation reactor, a cooling reactor, and a shaping machine connected in sequence. The continuous granulation reactor is filled with protective gas nitrogen, and the output end of the shaping machine is connected to a cyclone separator. The waste gas combustion treatment subsystem includes a burner, an SCR denitrification reactor, and a bag filter. The waste gas outlet of the continuous granulation reactor is connected to the burner through a pipeline, and the output end of the bag filter is connected to an induced draft fan and an exhaust stack. The waste heat utilization subsystem includes a gas-to-gas heat exchanger, which is connected to the combustion air duct of the burner, the flue gas outlet duct of the SCR denitrification reactor, and the nitrogen delivery duct.

[0017] The continuous granulation reactor includes a high-temperature reactor and a low-temperature reactor, which are separated by an annular baffle. The outer wall of the baffle is welded and the inner wall is reserved with a thermal expansion gap. Both the high-temperature reactor and the low-temperature reactor are equipped with flue gas regulating valves, namely valves 7-10, to regulate the flue gas volume and pressure inside the reactor.

[0018] The nitrogen system includes a nitrogen pressure-conveying-purging unit. The pipeline pressure of the nitrogen pressure-conveying-purging unit is maintained at around 20 kPa, and nitrogen purging points are set at the bends and equipment interfaces of the exhaust gas conveying pipeline. The purging direction is consistent with the airflow direction. The nitrogen conveying pipeline is first connected to a gas-to-gas heat exchanger for preheating nitrogen. The gas-to-gas heat exchanger adopts a two-stage heat exchange structure. The first stage is used for heat exchange between the flue gas and nitrogen after SCR denitrification, and the second stage is used for heat exchange between the flue gas after the first stage heat exchange and the combustion air. The regulating valve group of the burner includes valve 1, which is the biomass gas inlet valve, valve 2, which is the biomass gas supplementary heat valve, valve 3, which is the biomass gas main valve, valve 4, which is the waste gas supplementary heat valve, valve 5, which is the waste gas inlet valve, and valve 6, which is the waste gas supplementary heat auxiliary valve.

[0019] A biomass gasification method for heating and coating battery negative electrode materials includes the following steps: S1. Biomass pretreatment and gasification; S2. Biomass gas heating during system startup; S3. Exhaust gas replacement and temperature compensation; S4. Nitrogen System Control and Pipeline Purging S5. Two-stage heat exchange for waste heat utilization; S6. Coating granulation and finished product preparation.

[0020] S1 dries the biomass raw materials in a biomass raw material drying device and then feeds them into a biomass gasifier through a biomass feeding system. The raw materials are gasified in the gasifier to produce biochar, biogas, and biotar. The biochar is fed into a coke powder preparation system through a water-cooled char discharge device. The biogas and biotar are purified by a biogas purification device to remove most of the dust and tar, and then transported to the burner by a gas booster fan.

[0021] S2 refers to the early start of the biomass gasification subsystem, opening valves 1 and 3 of the burner to allow the biomass gas to mix and burn with the combustion air preheated by the gas-to-gas heat exchanger. The high-temperature flue gas generated by combustion is first introduced into the high-temperature reactor to maintain the temperature of the petroleum coke in the high-temperature reactor at 550~600℃, and then introduced into the low-temperature reactor to maintain the flue gas temperature in the low-temperature reactor at 300~400℃. The flue gas volume and the flue gas pressure in the reactor are adjusted by valves 7-10. At the same time, the petroleum coke is mechanically ground to 5~20μm and then mixed with the metered asphalt powder in a batch mixer, and then sent to the low-temperature reactor of the continuous granulation reactor through a tubular chain conveyor.

[0022] After being stirred at 300~400℃ for 2 hours in the S3 cryogenic reactor, the material is conveyed to the high-temperature reactor via a screw conveyor. In the high-temperature reactor, petroleum coke undergoes high-temperature decomposition, generating waste gas containing nitrogen, VOCs, tar, carbon powder, and oxygen. The waste gas flow rate satisfies Formula 1: V exhaust gas = V nitrogen + VVOCs Vexhaust gas is the total exhaust gas flow rate, Vnitrogen is the nitrogen volumetric flow rate, and VVOCs is the VOCs volumetric flow rate, both in m³ / h. The exhaust gas is delivered to the burner under its own pressure. Valve 5 is gradually opened and the opening of valve 3 is reduced, so that the exhaust gas gradually replaces the biomass gas as fuel. If the temperature of the cryogenic reactor is insufficient to be heated by the flue gas discharged from the high-temperature reactor, valves 2, 6 or 4 are opened to supplement the heat by burning biomass gas or exhaust gas to ensure that the temperature of the cryogenic reactor meets the standard.

[0023] In S4, adjust the nitrogen pressure control, delivery, and purging unit to increase the pressure inside the high-temperature reactor to 20 kPa, ensuring the nitrogen pressure meets the requirements of Formula 3. Pnitrogen = 1.2 × (Pexhaust gas resistance + Pgas pressure) Pnitrogen is the nitrogen pressure; Pexhaust gas resistance is the exhaust gas delivery pipeline resistance; Pgas pressure is the gas pressure required by the burner; all units are kPa. Nitrogen flow rate satisfies formula 4: V'nitrogen = 1.33 × Vnitrogen V' nitrogen is the nitrogen volumetric flow rate after modification, and V nitrogen is the nitrogen volumetric flow rate before modification. The units are both m³ / h. The oxygen content in the exhaust gas satisfies Formula 5: V'oxygen = 0.91 × Voxygen V'oxygen is the volumetric flow rate of oxygen in the exhaust gas after the modification, and Voxygen is the volumetric flow rate of oxygen in the exhaust gas before the modification. The units are both m³ / h. When the obstruction in the exhaust gas delivery pipeline increases significantly, open the nitrogen purging points at the pipeline bends and equipment interfaces, and purge the pipeline in the direction of airflow.

[0024] In the first stage of heat exchange in S5: the 300℃ flue gas from the SCR denitrification outlet enters the gas-to-gas heat exchanger, heating the nitrogen gas from 20℃ to 200℃, satisfying formula 6: 0.98 × V_flue gas × CV (flue gas) × (T_flue gas - T'_flue gas) = ​​V_nitrogen × CV (nitrogen) × (200 - 20) Vflue gas is the flue gas volumetric flow rate, in m³ / h; CV (flue gas) and CV (nitrogen) are the isochoric specific heats of flue gas and nitrogen, respectively, in kJ / (kg·℃); Tflue gas is the flue gas temperature before heat exchange, in ℃; T'flue gas is the flue gas temperature after the first stage of heat exchange, in ℃; the heat exchange efficiency is calculated as 98%. Second-stage heat exchange: The flue gas after the first-stage heat exchange continues to heat the combustion air in the gas-to-gas heat exchanger, raising the combustion air temperature from 20℃ to 250℃, satisfying Formula 7: 0.98 × Vflue gas × CV (flue gas) × (T'flue gas - T"flue gas) = Vair × CV (air) × (250 - 20) Vair is the volumetric flow rate of the combustion air, in m³ / h; CVair is the specific heat at constant volume of the combustion air, in kJ / (kg·℃); T"flue gas is the flue gas temperature after the second-stage heat exchange, in ℃. After heat exchange, the flue gas is successively treated by SCR denitrification and bag filter dust collector, and then sent to the exhaust stack by induced draft fan to meet emission standards.

[0025] After the petroleum coke in the S6 high-temperature reactor is coated and granulated at 550~600℃, it is sent to a cooling reactor to be cooled to below 60℃. The cooled material is then processed by a shaping machine (crushed and trimmed by high-speed rotating blades) to obtain particles with a particle size of 8~18μm. The outlet diameter D (mm) of the waste gas conveying pipeline meets the requirement of waste gas velocity V=10m / s, and the velocity calculation formula is 2: V = 4 × Vexhaust gas / (3600 × Π × D2); After shaping, the particles are separated, collected, and packaged in a cyclone separator to obtain the finished battery anode material. Carbon powder emission loss is reduced by more than 50%, and petroleum coke production capacity is increased by more than 1%.

[0026] A certain anode material coating and granulation project has eight 700kg / h petroleum coke coating and granulation production lines, with a heating power of 450kW per line. The existing waste gas treatment process is: two-stage water spray + electrostatic precipitator + RTO unit.

[0027] When starting the coating and granulation process system, the biomass gasification furnace gasification system is started in advance. The biomass gasification gas is used for heating. The material is heated to 300-400℃ in the low-temperature reactor and stirred for 2 hours. Then, the material is conveyed to the high-temperature reactor by a screw conveyor and heated to 550-600℃. The asphaltene material contained in the petroleum coke melts and coats the surface of the petroleum coke. The adhesive force of the asphaltene material is used to make the petroleum coke particles stick together. The gaps between the particles are filled with smaller particles to obtain the particles required by the process. After coating and granulation, the material enters the cooling reactor (each granulation reactor is equipped with a cooling reactor) and is cooled to below 60℃. The cooling reactor is a jacketed device. Circulating cooling water is circulated in the jacket. The cooling water and the material in the reactor are indirectly heated to cool the material. The cooled material is then sent to the shaping machine by the discharge screw conveyor.

[0028] When the coating granulation process system is operating normally, the petroleum coke raw material in the high-temperature reactor undergoes high-temperature decomposition, generating a mixture of high-temperature nitrogen, VOCs, tar, and carbon powder. Nitrogen accounts for 30% of the total volume, VOCs for 69%, and oxygen (Voxygen) for 1%; the carbon powder concentration is 140 g / Nm3; and the tar content is 100 g / Nm3. In this patent, this gas-solid combustible mixture is transported under its own pressure through a pipeline to the coating granulation burner for combustion. In the burner, the two fuels are regulated by a control valve group to gradually reduce the consumption of biomass gasification gas and increase the consumption of coating granulation waste gas, thereby maximizing energy conservation and emission reduction. Example 1: Biomass gasification process Considering a total heating power of 3600kW for the 8 production lines, and based on the biomass gasification furnace equipment selection, using biomass feedstock with 30% moisture content and a calorific value of 2500kJ / kg, one 2t / h fixed-bed suction gasifier will be installed. The calorific value of the biomass gas is assumed to be 1000kcal / Nm3. Under this operating condition, with a biomass gas price of 0.6 yuan / Nm3, the electric heating cost is calculated at 0.75 yuan / kWh, without considering the utilization of petroleum coke waste gas. (1) According to the existing electric heating technology, the cost of electric heating per hour is 3600×0.75=2700 yuan, which is equivalent to 482 yuan / t for heating each ton of petroleum coke.

[0029] (2) According to formulas 6 and 7, the final exhaust temperature is 153℃, and the amount of biomass gas consumed is 3660 Nm3 / h. The heating cost per hour is 3660 × 0.6 = 2196 yuan, which is equivalent to 392 yuan / t for heating each ton of petroleum coke.

[0030] (3) The waste gas treatment is still implemented in accordance with the two-stage water spray + electrostatic precipitator + RTO device scheme, which is consistent with the existing electric heating scheme.

[0031] Example 2: 50% biomass gas + 50% waste gas operation Considering a total heating power of 3600kW for the 8 production lines, and based on the biomass gasification furnace selection, using biomass feedstock with 30% moisture content and a calorific value of 2500kJ / kg, one 2t / h fixed-bed suction gasifier will be installed. The calorific value of the biomass gas is assumed to be 1000kcal / Nm3. Under this operating condition, with a biomass gas price of 0.6 yuan / Nm3, the electric heating cost is calculated at 0.75 yuan / kWh. The fuel gas is considered to be 50% biomass gas and 50% petroleum coke waste gas.

[0032] (1) According to the existing electric heating technology, the cost of electric heating per hour is 3600×0.75=2700 yuan, which is equivalent to 482 yuan / t for heating each ton of petroleum coke.

[0033] (2) According to formulas 6 and 7, the amount of biomass gas consumed is 1722 Nm3 / h, so the heating cost per hour is 1722 × 0.6 = 1033 yuan. At the same time, the capacity of each production line is increased to 703 kg, which is equivalent to a heating cost of 184 yuan / t per ton of petroleum coke.

[0034] (3) The waste gas does not need to be purified, saving about RMB 2 million per year in environmental protection and labor costs.

[0035] Example 3: 100% exhaust gas condition Considering a total heating power of 3600kW for the 8 production lines, and based on the biomass gasification furnace selection, using biomass feedstock with 30% moisture content and a calorific value of 2500kJ / kg, one 2t / h fixed-bed suction gasifier will be installed. The calorific value of the biomass gas is assumed to be 1000kcal / Nm3. Under this operating condition, with a biomass gas price of 0.6 yuan / Nm3, the electric heating cost is calculated at 0.75 yuan / kWh. The fuel gas is considered to be 100% petroleum coke waste gas.

[0036] (1) According to the existing electric heating technology, the cost of electric heating per hour is 3600×0.75=2700 yuan, which is equivalent to 482 yuan / t for heating each ton of petroleum coke.

[0037] (2) According to formulas 6 and 7, the biomass gas consumption is 0 Nm3 / h, so the heating cost per hour is 0 yuan, and the capacity of each production line is increased to 707 kg. The heating cost per ton of petroleum coke is 0 yuan / t.

[0038] (3) The waste gas does not need to be purified, saving about RMB 2 million per year in environmental protection and labor costs.

[0039] Finally, it should be noted that the above descriptions are merely preferred embodiments of the present invention and are not intended to limit the present invention. Although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art can still modify the technical solutions described in the foregoing embodiments or make equivalent substitutions for some of the technical features. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

Claims

1. A battery negative material coating granulation heating biomass gasification system, comprising a biomass gasification subsystem, a petroleum coke coating granulation heating subsystem, a waste gas combustion treatment subsystem and a waste heat utilization subsystem, characterized in that, The biomass gasification subsystem comprises, in sequence, a biomass raw material drying device, a biomass feeding system, a biomass gasification furnace, a biomass gas purification device, a water-cooled charcoal outlet device, and a gas booster fan, the output end of the water-cooled charcoal outlet device is connected to a coke powder preparation system, and the output end of the gas booster fan is connected to a burner. The petroleum coke coating and granulation heating subsystem comprises, in sequence, a mechanical grinder, a batch mixer, a pipe chain conveyor, a continuous granulation reaction kettle, a cooling kettle, and a shaper, the continuous granulation reaction kettle is filled with protective gas nitrogen, and the output end of the shaper is connected to a cyclone separation bin. The waste gas combustion treatment subsystem comprises a burner, an SCR denitration reactor, and a bag-type dust collector, the waste gas outlet of the continuous granulation reaction kettle is connected to the burner through a pipeline, and the output end of the bag-type dust collector is connected to an induced draft fan and an exhaust cylinder. The waste heat utilization subsystem comprises a gas-gas heat exchanger, which is connected to a combustion-supporting air pipeline of the burner, a flue gas outlet pipeline of the SCR denitration reactor, and a nitrogen gas conveying pipeline.

2. The biomass gasification system for coating granulation and heating of a battery negative material according to claim 1, characterized in that, The continuous granulation reaction kettle comprises a high-temperature kettle and a low-temperature kettle, the high-temperature kettle and the low-temperature kettle are separated by an annular baffle, the outer wall of the baffle is welded and the inner wall is provided with a thermal expansion gap, and flue gas regulating valves, i.e., valves 7-10, are arranged in the high-temperature kettle and the low-temperature kettle, respectively, for regulating the amount and pressure of flue gas in the kettle.

3. The biomass gasification system for coating granulation and heating of battery negative material according to claim 1, characterized in that, The nitrogen gas system comprises a nitrogen gas pressure-transportation-purging unit, the pipeline pressure of the nitrogen gas pressure-transportation-purging unit is maintained at 20 kPa, nitrogen gas purging points are arranged at the bends and equipment interfaces of the waste gas conveying pipeline, the purging direction is consistent with the gas flow direction, and the nitrogen gas conveying pipeline is connected to the gas-gas heat exchanger first for preheating nitrogen gas. The gas-gas heat exchanger adopts a two-stage heat exchange structure, the first stage is used for heat exchange between the flue gas after SCR denitration and nitrogen gas, and the second stage is used for heat exchange between the flue gas after the first stage of heat exchange and combustion-supporting air; and the regulating valve group of the burner comprises a biomass gas inlet valve 1, a biomass gas supplementary heating valve 2, a biomass gas main valve 3, a waste gas supplementary heating valve 4, a waste gas inlet valve 5, and a waste gas supplementary heating auxiliary valve 6.

4. A biomass gasification method for heating coated granulation of battery negative electrode material, applied to the biomass gasification system for heating coated granulation of battery negative electrode material according to any one of claims 1-3, characterized in that, The method comprises the following steps: S1. Biomass pretreatment and gasification; S2. Biomass gas heating in the system startup stage; S3. Waste gas replacement and temperature supplementary adjustment; S4. Nitrogen gas system control and pipeline purging S5. Two-stage heat exchange for waste heat utilization; S6. Coating, granulation, and product preparation.

5. The biomass gasification method for coating and granulating battery negative material for heating according to claim 4, characterized in that, In S1, the biomass raw material is dried by the biomass raw material drying device, then fed into the biomass gasification furnace through the biomass feeding system, and the raw material is gasified in the furnace to produce biomass charcoal, biomass gas, and biomass tar; the biomass charcoal is sent into the coke powder preparation system through the water-cooled charcoal outlet device, and the biomass gas and biomass tar are sent to the burner by the gas booster fan after most of the dust and tar are removed by the biomass gas purification device.

6. The biomass gasification method for heating of coated granulation of battery anode material according to claim 4, characterized in that, S2, i.e., the biomass gasification subsystem is started in advance, valves 1 and 3 of the combustor are opened, and the biomass gas is mixed and combusted with the combustion-supporting air preheated by the gas-gas heat exchanger; the high-temperature flue gas generated by the combustion is first introduced into the high-temperature kettle, so that the temperature of the petroleum coke in the high-temperature kettle is maintained at 550-600℃, and then introduced into the low-temperature kettle, so that the temperature of the flue gas in the low-temperature kettle is maintained at 300-400℃; the flue gas amount and the flue gas pressure in the kettle are adjusted through valves 7-10, and the petroleum coke is mechanically ground to 5-20μm, mixed with the metered asphalt powder in the mixing machine, and then sent into the low-temperature kettle of the continuous granulation reaction kettle through the pipe chain conveyor.

7. The biomass gasification method for coating and granulating battery negative material for heating according to claim 4, characterized in that, After the materials in the low-temperature kettle are stirred at 300-400℃ for 2h, they are conveyed to the high-temperature kettle by a screw conveyor; the petroleum coke in the high-temperature kettle is decomposed at high temperature to generate waste gas containing nitrogen, VOCs, tar, carbon powder and oxygen, and the waste gas flow rate satisfies formula 1: Vwaste gas=Vnitrogen+V VOCs Vwaste gas is the total flow rate of the waste gas, Vnitrogen is the volume flow rate of nitrogen, and V VOCs is the volume flow rate of VOCs, all in m³ / h; The waste gas is conveyed to the combustor by its own pressure, valves 5 are gradually opened, and the opening degree of valve 3 is reduced, so that the waste gas gradually replaces the biomass gas as the fuel; if the temperature of the low-temperature kettle is insufficiently heated by the flue gas discharged from the high-temperature kettle, valves 2, 6 or 4 are opened, and the biomass gas or the waste gas is combusted to supplement the heat, so as to ensure that the temperature of the low-temperature kettle meets the standard.

8. The biomass gasification method for coating and granulating battery negative material for heating according to claim 4, characterized in that, In S4, the nitrogen pressure-transportation-purging unit is adjusted, so that the kettle pressure in the high-temperature kettle is increased to 20kPa, and the nitrogen pressure satisfies formula 3: Pnitrogen=1.2×(Pwaste gas resistance+Pfuel gas pressure) Pnitrogen is the nitrogen pressure, Pwaste gas resistance is the resistance of the waste gas conveying pipeline, and Pfuel gas pressure is the required fuel gas pressure of the combustor, all in kPa; The nitrogen flow rate satisfies formula 4: V' nitrogen=1.33×Vnitrogen V' nitrogen is the volume flow rate of nitrogen after the modification, and Vnitrogen is the volume flow rate of nitrogen before the modification, both in m³ / h; The oxygen content in the waste gas satisfies formula 5: V' oxygen=0.91×Voxygen V' oxygen is the volume flow rate of oxygen in the waste gas after the modification, and Voxygen is the volume flow rate of oxygen in the waste gas before the modification, both in m³ / h; When the resistance loss of the waste gas conveying pipeline obviously increases, nitrogen purging points at the pipeline bends and equipment interfaces are opened, and the pipeline is purged along the airflow direction.

9. The biomass gasification method for heating of coated granulation of battery anode material according to claim 4, characterized in that, In S5, the first-stage heat exchange: the 300℃ flue gas at the outlet of the SCR denitration is introduced into the gas-gas heat exchanger to heat the nitrogen, so that the temperature of the nitrogen is increased from 20℃ to 200℃, and formula 6 is satisfied: 0.98×Vflue gas×CV(flue gas)×(Tflue gas-T'flue gas)=Vnitrogen×CV(nitrogen)×(200-20) Vflue gas is the volume flow rate of the flue gas, in m³ / h; CV(flue gas) and CV(nitrogen) are the constant volume specific heat of the flue gas and the nitrogen, respectively, in kJ / (kg・℃); Tflue gas is the temperature of the flue gas before the heat exchange, in ℃; T'flue gas is the temperature of the flue gas after the first-stage heat exchange, in ℃; and the heat exchange efficiency is 98%; Second stage heat exchange: the flue gas after the first stage heat exchange continues to heat the combustion air in the gas-gas heat exchanger, and the temperature of the combustion air is raised from 20℃ to 250℃, satisfying formula 7: 0.98×Vflue gas×CV(flue gas)×(T'flue gas-T''flue gas)=Vair×CV(air)×(250-20) Vair is the volume flow of the combustion air, in m³ / h; CV(air) is the specific heat capacity of the combustion air, in kJ / (kg・℃); T''flue gas is the temperature of the flue gas after the second stage heat exchange, in ℃; The flue gas after the heat exchange is treated by SCR denitration and bag filter, and then is sent to the exhaust pipe by the induced draft fan for standard emission.

10. The biomass gasification method for heating of coated granulation of battery anode material according to claim 4, characterized in that, After the high-temperature petroleum coke in S6 is coated and granulated at 550-600℃, it is sent to a cooling kettle to be cooled to below 60℃; the cooled material is treated by a shaping machine (by high-speed rotating blades to crush and trim the corners) to obtain particles with a particle size of 8-18μm; the outlet diameter D (mm) of the waste gas conveying pipeline satisfies the waste gas flow rate V=10m / s, and the flow rate calculation formula 2: V=4×Vwaste gas / (3600×Π×D2); The shaped particles are separated and collected by a cyclone separation bin, and are packaged to obtain the finished battery negative electrode material, with the carbon powder emission loss reduced by more than 50% and the petroleum coke production capacity increased by more than 1%.

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