Method and system for utilizing flue gas generated after petroleum coke calcination

Abstract

The invention provides a method and system for utilizing flue gas generated after petroleum coke calcination, and belongs to the field of aluminum electrolysis and aluminum carbon. The method comprises the following steps: collecting high-temperature flue gas discharged after calcining petroleum coke; the high-temperature flue gas is subjected to heat exchange treatment, and low-temperature flue gas with the set temperature is obtained; low-temperature flue gas is used as a heat source, the wet-based petroleum coke is heated and dried, and dry-based petroleum coke with a set water value is obtained; and calcining the dry-based petroleum coke, and circularly using flue gas collected by calcining for heating and drying the wet-based petroleum coke to form a closed cycle. High-temperature flue gas obtained after calcination is subjected to heat exchange to form low-temperature flue gas, the low-temperature flue gas is used for drying wet-based petroleum coke, a flue gas circulation system is formed, and multi-stage utilization of waste heat is achieved. Meanwhile, the dried petroleum coke can reduce energy consumption required by water evaporation during calcination, and erosion of water vapor to a hearth refractory material is avoided. Therefore, the negative influence of petroleum coke moisture on the heat efficiency is reduced while the waste heat utilization rate after petroleum coke calcination is improved.

Description

Technical Field

[0001] This application relates to the technical fields of aluminum electrolysis and carbon for aluminum, and particularly relates to a method and system for utilizing the flue gas after calcining petroleum coke. Background Art

[0002] The main raw materials for the production of prebaked anodes for aluminum are petroleum coke and pitch. Among them, petroleum coke is produced by the method of flushing out the coke in the coking tower with high-pressure water, and the coke is stored in the coke pond after discharging. The moisture content of the petroleum coke obtained by prebaked anode manufacturers through transportation is generally 8-13%. This part of the moisture will cause problems such as steel structure corrosion during the processes of petroleum coke transportation, crushing, and storage. At the same time, it has the greatest impact on the calcination process. During the calcination process, this part of the moisture needs to be evaporated, which not only wastes heat, but also the steam may cause the refractory materials such as silica bricks used for the lining of the pot-type calciner to burst, affecting the service life of the pot-type calciner furnace body.

[0003] The main methods for calcining petroleum coke for prebaked anodes for aluminum are rotary kilns and down-flow pot-type calciners. For the calcined coke products, only down-flow pot-type calciners are usually used. The temperature of the flue gas discharged from the pot-type calciner can reach above 850°C. Generally, the methods for heat recovery are as follows: One method is to conduct partial heat recovery through a heat transfer oil furnace system. After the heat recovery, the flue gas temperature is about 250°C, and it is discharged through desulfurization and other systems. The heat recovered in this part is mainly used for processes such as asphalt melting, pipeline heat preservation, kneading pot heating, and molding machine heating during the production of prebaked anodes for aluminum; Another method is that the flue gas discharged from the pot-type calciner passes through a waste heat boiler system. It is sent to the economizer through a feed water pump to be heated to saturated steam and introduced into the steam drum of the waste heat boiler. The saturated water in the steam drum enters the evaporator through the downcomer. The steam-water mixture in the evaporator enters the steam drum through the steam-water introduction pipe. The steam and water in the steam drum are separated, and the saturated steam enters the superheater. After the steam is superheated, it is first sent to power generation equipment for power generation. The backpressure steam after power generation is incorporated into the medium and low-pressure steam pipe network for other production processes. After the heat is recovered by the waste heat boiler system and the temperature drops to about 200°C, it enters the flue gas desulfurization system or is directly discharged through an induced draft fan. As a result, the waste heat utilization rate after calcining petroleum coke is low. However, in the current existing technologies, there is no method for using the flue gas after calcining petroleum coke to heat and dry the moisture of petroleum coke. Summary of the Invention

[0004] This application provides a method and system for utilizing the flue gas after calcining petroleum coke to solve the following technical problems: how to improve the waste heat utilization rate after calcining petroleum coke while reducing the negative impact of the moisture of petroleum coke on the thermal efficiency.

[0005] In the first aspect, an embodiment of this application provides a method for utilizing the flue gas after calcining petroleum coke, and the method includes:

[0006] Collect the high-temperature flue gas discharged after calcining petroleum coke;

[0007] The high-temperature flue gas is subjected to heat exchange treatment to obtain low-temperature flue gas with a set temperature;

[0008] Using the low-temperature flue gas as a heat source, the wet petroleum coke is heated and dried to obtain dry petroleum coke with a set moisture value; and

[0009] The dry petroleum coke is calcined, and the flue gas collected from the calcination is recycled for heating and drying the wet petroleum coke to form a closed cycle.

[0010] Optionally, the temperature of the high-temperature flue gas ≥ 850 °C.

[0011] Optionally, the temperature of the low-temperature flue gas is 200 °C - 300 °C.

[0012] Optionally, the set moisture value ≤ 3%.

[0013] Optionally, the moisture value of the wet petroleum coke is 8% - 13%.

[0014] Optionally, the temperature of the calcination is 1250 °C - 1350 °C.

[0015] In a second aspect, the present application provides a system for utilizing the flue gas after calcining petroleum coke. The system is adapted to the method described in any one of the embodiments in the first aspect. The system includes:

[0016] A pot-type calcining furnace provided with an inlet for dry petroleum coke and an outlet for high-temperature flue gas;

[0017] A heat exchange device provided with an inlet for high-temperature flue gas and an outlet for low-temperature flue gas. The high-temperature flue gas inlet of the heat exchange device is connected to the high-temperature flue gas outlet of the pot-type calcining furnace, and is used for subjecting the high-temperature flue gas to heat exchange treatment to obtain low-temperature flue gas;

[0018] A drying device provided with a gas inlet, an inlet for wet petroleum coke, and an outlet for dry petroleum coke. The gas inlet of the drying device is connected to the low-temperature flue gas outlet of the heat exchange device, and the dry petroleum coke outlet of the drying device is connected to the dry petroleum coke inlet of the pot-type calcining furnace, and is used for heating and drying the wet petroleum coke with the low-temperature flue gas as a heat source.

[0019] Optionally, the heat exchange device is a waste heat heat-conducting oil boiler or a waste heat steam boiler.

[0020] Optionally, the drying device is a fixed drying device or a rotary drum drying device.

[0021] Optionally, the system further includes:

[0022] A blower, used to convey the low-temperature flue gas to the drying device.

[0023] The above technical solution provided by the embodiments of the present application has the following advantages compared with the prior art:

[0024] The embodiments of the present application provide a method for utilizing the flue gas after calcining petroleum coke, the method includes: collecting the high-temperature flue gas discharged after calcining petroleum coke; performing heat exchange treatment on the high-temperature flue gas to obtain low-temperature flue gas with a set temperature; using the low-temperature flue gas as a heat source to heat and dry wet-base petroleum coke to obtain dry-base petroleum coke with a set moisture value; and calcining the dry-base petroleum coke, and recycling the flue gas collected from the calcination for heating and drying wet-base petroleum coke to form a closed cycle. By exchanging heat of the high-temperature flue gas after calcination into low-temperature flue gas and then using it for drying wet-base petroleum coke, a flue gas circulation system is formed to realize multi-stage utilization of waste heat. At the same time, in the traditional calcination process, only part of the waste heat of the high-temperature flue gas is recovered, while in this solution, the comprehensive heat recovery rate is improved through a closed cycle. In addition, the moisture content of the dried petroleum coke is ≤3%, reducing the energy consumption required for moisture evaporation during calcination and avoiding the erosion of the furnace refractory by water vapor. Thus, while improving the utilization rate of waste heat after calcining petroleum coke, the negative impact of the moisture content of petroleum coke on the thermal efficiency is reduced. Description of the Drawings

[0025] The drawings here are incorporated into the description and form a part of this description, showing embodiments consistent with the present application and used together with the description to explain the principles of the present application.

[0026] In order to more clearly illustrate the technical solutions in the embodiments of the present application or the prior art, the following will briefly introduce the drawings required for use in the description of the embodiments or the prior art. Obviously, for those of ordinary skill in the art, without creative efforts, other drawings can also be obtained based on these drawings.

[0027] Figure 1 It is a schematic flow chart of a method for utilizing the flue gas after calcining petroleum coke provided by the embodiments of the present application;

[0028] Figure 2 It is a schematic actual flow chart of a method for utilizing the flue gas after calcining petroleum coke provided by the embodiments of the present application;

[0029] Figure 3 It is a schematic structural diagram of a system for utilizing the flue gas after calcining petroleum coke provided by the embodiments of the present application;

[0030] Reference Signs:

[0031] 1-pot type calcining furnace, 2-heat exchange device, 3-drying device, 4-blower. Detailed Embodiments

[0032] To make the objectives, technical solutions, and advantages of the embodiments of this application clearer, the following will clearly and completely describe the technical solutions in the embodiments of this application with reference to the accompanying drawings in the embodiments of this application. Obviously, the described embodiments are some but not all of the embodiments of this application. All other embodiments obtained by those of ordinary skill in the art based on the embodiments in this application without creative efforts shall fall within the scope of protection of this application.

[0033] The various embodiments of this application may exist in the form of a range; it should be understood that the description in the form of a range is only for convenience and brevity and should not be construed as a rigid limitation on the scope of this application; therefore, it should be considered that the range description has specifically disclosed all possible sub-ranges and individual values within that range. For example, it should be considered that the range description from 1 to 6 has specifically disclosed sub-ranges such as from 1 to 3, from 1 to 4, from 1 to 5, from 2 to 4, from 2 to 6, from 3 to 6, etc., and individual numbers within that range, such as 1, 2, 3, 4, 5, and 6, and this applies regardless of the range. Additionally, whenever a numerical range is indicated herein, it means including any cited number (fraction or integer) within the indicated range.

[0034] In addition, in the description of the specification of this application, terms such as "including" and "comprising" mean "including but not limited to". In this text, relational terms such as "first" and "second" are only used to distinguish one entity or operation from another entity or operation, and do not necessarily require or imply any such actual relationship or order between these entities or operations. In this text, "and / or" describes the association relationship of associated objects, indicating that there can be three relationships. For example, A and / or B can mean: A exists alone, A and B exist simultaneously, and B exists alone. Where A and B can be singular or plural. In this text, "at least one" means one or more, and "multiple" means two or more. "At least one kind", "at least one item (one) below" or similar expressions refer to any combination of these items, including any combination of single item (one) or plural items (ones). For example, "at least one item (one) of a, b, or c", or, "at least one item (one) of a, b, and c" can both mean: a, b, c, a - b (that is, a and b), a - c, b - c, or a - b - c, where a, b, and c can be single or multiple respectively. The "parts representation method" such as weight parts and mass parts represents the proportional relationship between each component. In the proportional relationships involved in this text, the parameters that need to be described by proportion should be understood as the antecedents of the proportion formula in the order of description, and the proportional numbers should be understood as the consequents of the proportion formula. For example, if the mass ratio of substance A, substance B, and substance C is 1:2:3, then substance A, substance B, and substance C should correspond one by one with the proportional numbers in the proportion formula in the order of description, that is, the mass of substance A: the mass of substance B: the mass of substance C = 1:2:3.

[0035] Unless otherwise specifically stated, various raw materials, reagents, instruments, and equipment used in this application can be obtained through market purchases or can be prepared by existing methods.

[0036] Figure 1 It is a schematic flow chart of a method for utilizing the flue gas after calcining petroleum coke provided by an embodiment of this application; Figure 2 It is a schematic actual flow chart of a method for utilizing the flue gas after calcining petroleum coke provided by an embodiment of this application.

[0037] As Figure 1 and Figure 2 shown, this application provides a method for utilizing the flue gas after calcining petroleum coke, and the method includes:

[0038] S1. Collect the high-temperature flue gas discharged after calcining petroleum coke;

[0039] S2. Conduct heat exchange treatment on the high-temperature flue gas to obtain low-temperature flue gas with a set temperature;

[0040] S3. Using the low-temperature flue gas as a heat source, heat and dry the wet petroleum coke to obtain dry petroleum coke with a set moisture value.

[0041] S4. Calcinate the dry petroleum coke, and recycle the flue gas collected during the calcination for heating and drying the wet petroleum coke to form a closed cycle.

[0042] In some embodiments, the temperature of the high-temperature flue gas ≥ 850 °C.

[0043] The high-temperature flue gas is sourced from the waste heat generated by the combustion of volatile components during the calcination of petroleum coke. Direct emission would cause energy waste, and the high-temperature flue gas needs to be heat-recovered and reused first. The calcination temperature generally needs to reach 1250 - 1350 °C, and the initial temperature of the flue gas after combustion exceeds 850 °C. Exemplarily, the temperature of the high-temperature flue gas can be 850 °C, 860 °C, 870 °C, 880 °C, 890 °C, 900 °C, etc.

[0044] In some embodiments, the temperature of the low-temperature flue gas is 200 °C - 300 °C.

[0045] Through a heat exchange device, the high-temperature flue gas is cooled to the medium-low temperature range (200 - 300 °C), which not only meets the drying requirement but also avoids the heat pollution caused by the direct emission of low-temperature flue gas. At the same time, 200 - 300 °C is the optimal temperature window for the drying process, which can effectively evaporate moisture and avoid the pyrolysis or agglomeration of petroleum coke. Exemplarily, the temperature of the low-temperature flue gas can be 200 °C, 220 °C, 240 °C, 260 °C, 280 °C, 300 °C, etc.

[0046] In some embodiments, the set moisture value ≤ 3%.

[0047] In some embodiments, the moisture value of the wet petroleum coke is 8% - 13%.

[0048] Direct calcination of high-moisture petroleum coke will prolong the heating time, increase energy consumption, and the steam generated during moisture evaporation will damage the furnace refractory. Drying to ≤ 3% can meet the requirement of the calcination process for the moisture of raw materials. After drying, the porosity of the coke decreases, and it is heated more evenly during calcination, reducing local overburning or underburning phenomena, thereby improving the product performance of the calcined coke. Exemplarily, the moisture value of the dry petroleum coke can be 1%, 1.2%, 1.5%, 2%, 2.5%, 3%, etc.

[0049] In some embodiments, the temperature of the calcination is 1250 °C - 1350 °C.

[0050] By calcination, the volatile components of petroleum coke are removed at high temperature, the fixed carbon content and true density are increased, and the powder resistivity is reduced. The flue gas after calcination is reused for drying, forming a cascaded utilization of waste heat, reducing external energy consumption, while reducing the flue gas emissions and alleviating the environmental protection pressure. Exemplarily, the calcination temperature can be 1250 °C, 1270 °C, 1290 °C, 1300 °C, 1320 °C, 1340 °C, 1350 °C, etc.

[0051] Figure 3 The figure is a schematic structural diagram of a system for utilizing the flue gas after calcining petroleum coke provided by an embodiment of the present application.

[0052] As Figure 3 shown, the present application provides a system for utilizing the flue gas after calcining petroleum coke. The system is adapted to the method described in any one of the above embodiments. The system includes:

[0053] A pot-type calciner 1, which is provided with a dry-base petroleum coke inlet and a high-temperature flue gas outlet;

[0054] A heat exchange device 2, which is provided with a high-temperature flue gas inlet and a low-temperature flue gas outlet. The high-temperature flue gas inlet of the heat exchange device 2 is communicated with the high-temperature flue gas outlet of the pot-type calciner 1, and is used for heat-exchanging the high-temperature flue gas to obtain low-temperature flue gas;

[0055] A drying device 3, which is provided with a gas inlet, a wet-base petroleum coke inlet and a dry-base petroleum coke outlet. The gas inlet of the drying device 3 is communicated with the low-temperature flue gas outlet of the heat exchange device 2, and the dry-base petroleum coke outlet of the drying device 3 is communicated with the dry-base petroleum coke inlet of the pot-type calciner 1, and is used for heating and drying the wet-base petroleum coke with the low-temperature flue gas as the heat source.

[0056] In some embodiments, the heat exchange device 2 is a waste heat heat-conducting oil boiler or a waste heat steam boiler.

[0057] The waste heat heat-conducting oil boiler or the waste heat steam boiler can recover heat for power generation or heating.

[0058] In some embodiments, a dust removal device (such as a cyclone separator) needs to be provided before the high-temperature flue gas inlet of the heat exchange device 2 to prevent dust from clogging the heat exchange pipeline.

[0059] In some embodiments, the drying device 3 is a fixed drying device 3 or a rotary drum drying device 3.

[0060] In some embodiments, the system further includes:

[0061] A blower 4, which is used for conveying the low-temperature flue gas into the drying device 3.

[0062] In some embodiments, the system further includes:

[0063] A flue gas desulfurization and purification system, which is connected to the gas outlet of the drying device 3 and is used to treat the discharged flue gas of the drying device 3.

[0064] Thus, for a method and system for utilizing the flue gas after calcining petroleum coke provided by an embodiment of the present application, before the calcination process, the low-temperature flue gas recovered by the waste heat boiler or the heat-conducting oil boiler of the pot-type calciner is collected to dry the wet-base petroleum coke. The dried dry-base petroleum coke then enters the pot-type calciner for calcination. The present invention realizes the efficient utilization of the waste heat of the calciner, significantly reduces the negative impact of the moisture of the petroleum coke on the thermal efficiency, and at the same time reduces the erosion of the steel structure and refractory materials, effectively prolongs the service life of the furnace body, and has the advantages of energy conservation and environmental protection, improving production efficiency, and reducing maintenance costs.

[0065] In summary, the method and system for utilizing the flue gas after calcining petroleum coke provided by the embodiments of the present application have the following advantages:

[0066] (1) Efficient cascade utilization of waste heat, significantly reducing energy consumption: By exchanging heat of the high-temperature flue gas (≥850 °C) after calcination through a waste heat boiler (heat-conducting oil / steam type) to 200 - 300 °C and then using it to dry the wet-base petroleum coke (initial moisture 8 - 13% → dried to ≤3%), a flue gas circulation system is formed to realize multi-stage utilization of waste heat. At the same time, in the traditional calcination process, only part of the waste heat of the high-temperature flue gas is recovered (about 30% is not utilized), while in this solution, through a closed cycle, the comprehensive heat recovery rate is increased by 10 - 20%. In addition, the waste heat boiler can convert the heat of the flue gas into steam or heat-conducting oil for power generation or heating, further reducing the dependence on external energy.

[0067] (2) Improving calcination efficiency and product quality: The moisture content of the petroleum coke after drying is ≤3%, reducing the energy consumption required for moisture evaporation during calcination and avoiding the erosion of the furnace lining refractory by water vapor. At the same time, the porosity of the low-moisture coke decreases, the heating is more uniform, reducing local overburning or underburning phenomena, and the true density of the calcined coke is increased to 2.05 - 2.09 g / cm 3 , and the powder resistivity is reduced to 400 - 500 μΩ·m, meeting the high requirements of industries such as electrolytic aluminum and steel for carbon materials. In addition, with a calcination temperature of 1250 - 1350 °C combined with the structure of a downflow pot-type furnace, the volatile matter removal rate is increased and the fixed carbon content is increased.

[0068] (3) Extend the equipment life and reduce the maintenance cost: The low-moisture petroleum coke after drying reduces the chemical erosion of the furnace body by steam during calcination. At the same time, a dust removal device (such as a cyclone separator) is set before the flue gas circulation to prevent the powdered coke from blocking the heat exchange pipeline. At the same time, the pot-type calciner adopts a co-current design and is equipped with a closed cooling system to reduce the damage of thermal stress to the furnace body and extend the operation life of the equipment.

[0069] The following will further elaborate on this application in combination with specific embodiments. It should be understood that these embodiments are only used to illustrate this application and not to limit the scope of this application. The experimental methods without specific conditions noted in the following embodiments are usually determined according to industry standards. If there is no corresponding industry standard, they are carried out according to general international standards, conventional conditions, or the conditions recommended by the manufacturer.

[0070] Example 1

[0071] The petroleum coke containing 10% moisture is conveyed to the petroleum coke buffer bin through a belt conveyor and evenly added to a rotary drum dryer. The drying equipment is φ1500×3000mm; the high-temperature flue gas from 32 groups of 8-layer co-current pot-type calciners has a temperature of about 950°C. After the heat is recovered by a waste heat heat-conducting oil boiler, the discharged low-temperature flue gas has a temperature of about 280°C; a part of the low-temperature flue gas is introduced into the dryer by an induced draft fan, and the flue gas flow rate is about 380 Nm per hour 3 / tank; adjust the rotation speed of the drying equipment and the feeding amount of the wet-based petroleum coke to control the moisture of the dried petroleum coke to be less than 2.8%; the 180°C tail gas discharged from the dryer is connected to the original pot-type calciner flue gas treatment system, and after treatment, it meets the standards and is discharged; the dried petroleum coke is added to the feeding device of the pot-type calciner and calcined at 1250°C to obtain qualified calcined coke. The true density of the calcined coke is 2.05 g / cm 3 , and the powder specific resistance is 500 μΩ·m. At the same time, the effective utilization rate of the heat energy of the pot-type calciner is increased by about 12%.

[0072] Example 2

[0073] The petroleum coke containing 12% moisture is conveyed to the buffer bin through a belt conveyor and evenly added to a rotary drum dryer. The drying equipment is φ2000×6000mm; the high-temperature flue gas from 40 groups of 8-layer co-current pot-type calciners has a temperature of about 1000°C. After the heat is recovered by a waste heat heat-conducting oil boiler and a waste heat steam boiler, the discharged low-temperature flue gas has a temperature of about 220°C; a part of the low-temperature flue gas is introduced into the dryer by an induced draft fan, and the flue gas flow rate is about 450 Nm per hour 3 / Tank; adjust the rotation speed of the drying equipment and the feeding amount of wet petroleum coke to control the moisture content of the dried petroleum coke to be less than 3%; the 160°C tail gas discharged from the dryer is connected to the original flue gas treatment system of the tank type calciner, and after treatment, it meets the standards and is discharged; add the dried petroleum coke to the feeding device of the tank type calciner and calcine it at 1280°C to obtain qualified calcined coke, and the true density of the calcined coke is 2.06 g / cm 3 , and the powder specific resistance is 480 μΩ·m. At the same time, the effective utilization rate of the heat energy of the tank type calciner is increased by about 18%.

[0074] Example 3

[0075] Load the petroleum coke with 8% moisture in layers and spread it flat in the drying room. The high-temperature flue gas from 40 groups of 10-layer downflow tank type calciners is about 900°C. After the heat is recovered by the waste heat heat-conducting oil boiler, the discharged low-temperature flue gas is about 260°C; a part of the low-temperature flue gas is introduced into the drying room by an induced draft fan, and the flue gas flow rate is about 520 Nm per hour 3 / Tank; adjust the drying time and the loading amount of wet petroleum coke to control the moisture content of the dried petroleum coke to be less than 2.5%; the 150°C tail gas discharged from the drying is connected to the original flue gas treatment system of the tank type calciner, and after treatment, it meets the standards and is discharged; add the dried petroleum coke to the feeding device of the tank type calciner and calcine it at 1320°C to obtain qualified calcined coke, and the true density of the calcined coke is 2.09 g / cm 3 , and the powder specific resistance is 440 μΩ·m. At the same time, the effective utilization rate of the heat energy of the tank type calciner is increased by about 15%.

[0076] In addition, one or more technical solutions in the embodiments of the present application at least have the following technical effects or advantages:

[0077] In the embodiments of the present application, the high-efficient utilization of the waste heat of the downflow tank type calciner is realized, and the negative impact of the moisture in the wet petroleum coke on the thermal efficiency of the calciner is significantly reduced.

[0078] In the embodiments of the present application, by reducing the erosion of moisture on the steel structure and refractory materials (such as silica bricks), the service life of the calciner is extended.

[0079] In the embodiments of the present application, the provided method has the advantages of energy conservation, environmental protection, improving thermal efficiency, and extending the equipment life, and is applicable to the optimization and upgrading of the petroleum coke calcination process.

[0080] The above are only specific embodiments of the present application, enabling those skilled in the art to understand or implement the present application. Various modifications to these embodiments will be obvious to those skilled in the art, and the general principles defined herein can be implemented in other embodiments without departing from the spirit or scope of the present application. Therefore, the present application will not be limited to these embodiments shown herein, but rather will be accorded the widest scope consistent with the principles and novel features claimed herein.

Claims

1. A method for utilizing flue gas after calcining petroleum coke, the method comprising: Collect high-temperature flue gas emitted after calcining petroleum coke; The high-temperature flue gas is subjected to heat exchange treatment to obtain low-temperature flue gas with a set temperature; Using the low-temperature flue gas as a heat source, the wet-based petroleum coke is heated and dried to obtain dry-based petroleum coke with a set moisture value; as well as The dry-based petroleum coke is calcined, and the flue gas collected from the calcination is recycled for heating and drying the wet-based petroleum coke, forming a closed cycle.

2. The method according to claim 1, characterized in that The temperature of the high-temperature flue gas is ≥850°C.

3. The method according to claim 1, characterized in that The temperature of the low-temperature flue gas is 200°C to 300°C.

4. The method according to claim 1, characterized in that The set moisture value is ≤3%.

5. The method according to claim 1, characterized in that The moisture value of the wet-based petroleum coke is 8% to 13%.

6. The method according to claim 1, characterized in that The calcination temperature is 1250°C to 1350°C.

7. A system for utilizing flue gas after calcination of petroleum coke, the system being adapted to the method according to any one of claims 1 to 6, the system comprising: A pot-type calcining furnace, wherein the pot-type calcining furnace (1) is provided with a dry petroleum coke inlet and a high-temperature flue gas outlet; A heat exchange device (2), wherein the heat exchange device (2) is provided with a high-temperature flue gas inlet and a low-temperature flue gas outlet, and the high-temperature flue gas inlet of the heat exchange device (2) is connected to the high-temperature flue gas outlet of the pot-type calcining furnace (1) and is used to perform heat exchange treatment on the high-temperature flue gas to obtain low-temperature flue gas; A drying device (3), wherein the drying device (3) is provided with a gas inlet, a wet petroleum coke inlet and a dry petroleum coke outlet, the gas inlet of the drying device (3) being connected to the low-temperature flue gas outlet of the heat exchange device (2), and the dry petroleum coke outlet of the drying device (3) being connected to the dry petroleum coke inlet of the pot-type calcining furnace (1), and being used for heating and drying the wet petroleum coke using the low-temperature flue gas as a heat source.

8. The system according to claim 7, characterized in that The heat exchange device (2) is a waste heat thermal oil boiler or a waste heat steam boiler.

9. The system according to claim 7, characterized in that The drying device (3) is a fixed drying device or a rotary drum drying device.

10. The system according to claim 7, characterized in that The system further comprises: A blower (4) is used to transport the low-temperature flue gas to the drying device.

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