Process and system for calcination of fluidized suspension roasted petroleum coke

Abstract

The present application relates to the field of energy-saving and environment-friendly production technology, in particular to a calcination method and system for flow-suspension roasting of petroleum coke. The method comprises: feeding petroleum coke raw materials into a multi-stage preheating system for countercurrent preheating; after preheating, the materials enter a flow-suspension roasting furnace to form a suspension state in a high-temperature airflow for rapid roasting; after roasting, the materials are separated from the flue gas, the separated flue gas containing volatile components is combusted in a combustion furnace and then subjected to purification treatment, and the heat is partially recycled; the separated high-temperature calcined coke is cooled through an air cooling and water cooling system and the heat is recovered, and the hot air generated by air cooling is recycled to the roasting furnace. The present application uses fluidization technology to shorten the roasting time to seconds, significantly improving the production efficiency; through multi-stage countercurrent heat exchange, flue gas combustion and heat recycling, the present application realizes heat cascade utilization and precise atmosphere control, greatly reduces energy consumption and oxidation loss, and stably controls the volatile component of the product below 1%, with high yield and uniform quality.

Description

Technical Field

[0001] This invention relates to the field of energy-saving and environmentally friendly production technology, specifically to a calcination method and system for fluidized suspension roasting of petroleum coke. Background Technology

[0002] Petroleum coke is a key raw material for aluminum-based carbon, graphite electrodes, and high-end carbon materials. Its calcination quality directly affects the electrical properties, thermal stability, and mechanical strength of subsequent products. Currently, traditional equipment such as pot furnaces and rotary kilns are mainly used in industry for petroleum coke calcination, but the following problems are common: the calcination time of traditional pot furnaces or rotary kilns is usually 8 to 80 hours, resulting in low production efficiency; the sensible heat of high-temperature flue gas and calcined coke is not effectively recovered, leading to low system thermal efficiency; petroleum coke easily reacts with residual oxygen at high temperatures, resulting in a decrease in yield; it is difficult to stably control the volatile matter content below 1%; and the equipment is large in size and has a low level of automation, limiting the promotion of large-scale and intelligent production.

[0003] In recent years, several improved technologies have been proposed. For example, Chinese patent application CN117308595A, published on December 29, 2023, discloses a petroleum coke calcination system and its process. This system combines a tank-type calciner with an electrically heated high-temperature calciner, achieving high-temperature treatment of 1200-2500℃ through segmented heating. While this improves the calcination temperature to some extent, it remains an intermittent operation and does not solve the problems of flue gas waste heat recovery and atmosphere control. Chinese patent application CN121163231A, published on December 19, 2025, discloses a petroleum coke drying and calcination system. This system utilizes calcination tail gas for secondary use in the drying process, achieving partial waste heat recovery. However, the overall structure remains a rotary kiln, resulting in a relatively long calcination time and limited control over oxidation loss. Chinese patent application CN101955785A, published on January 26, 2011, discloses a system and method for two-stage calcination of petroleum coke in a rotary kiln. Although the system uses high-temperature flue gas to preheat the petroleum coke raw material and reduces the moisture content, it still fails to achieve rapid roasting and closed-loop atmosphere control, resulting in limited yield improvement.

[0004] In summary, existing technologies have not yet achieved comprehensive breakthroughs in terms of high efficiency, energy saving, low loss, and automation. There is an urgent need for a new method for calcining petroleum coke that can significantly shorten the calcination time while achieving the goals of low volatile matter, high yield, low energy consumption, and low cost. Summary of the Invention

[0005] In view of the shortcomings of the prior art, the purpose of this invention is to provide a calcination method for petroleum coke by fluid suspension roasting. The method adopts the principle of fluid suspension roasting, which ensures sufficient gas-solid contact and fast heat and mass transfer rate. It reduces the roasting time of petroleum coke from 8-80 hours in traditional pot furnaces or rotary kilns to within 10 minutes, which greatly improves the processing capacity and production efficiency of a single unit.

[0006] Another objective of this invention is to provide a calcination system for fluidized suspension roasting of petroleum coke. Through a multi-stage countercurrent preheating system for materials and flue gas, and a multi-stage countercurrent cooling system for calcined coke and cooling medium, the system achieves the cascade recovery and recycling of high-temperature flue gas and high-temperature finished product sensible heat within the system, resulting in extremely high thermal efficiency and significantly reducing energy consumption per unit product.

[0007] This invention is achieved using the following technical solution:

[0008] The calcination method for the fluidized suspension roasted petroleum coke includes the following steps:

[0009] a) The petroleum coke feedstock is fed into a multi-stage preheating system heated by flue gas for countercurrent preheating;

[0010] b) The preheated petroleum coke is fed into a fluidized suspension roasting furnace, where it is rapidly roasted in a fluidized suspension state under the action of high-temperature airflow.

[0011] c) Separate the high-temperature roasted material from the high-temperature flue gas;

[0012] d) Recycle a portion of the high-temperature flue gas separated in step c) to the fluidized bed roasting furnace and / or the multi-stage preheating system, and use an online gas analyzer to monitor and control the oxygen content of the atmosphere in the roasting furnace in a closed loop to suppress the oxidative loss of petroleum coke.

[0013] e) The high-temperature calcined coke separated in step c) is sent to a cooling system consisting of a material air cooler and a material water cooler for cooling, and the heat released in the material air cooler is recovered.

[0014] The petroleum coke feedstock is carried by flue gas and passes through each stage of the multi-stage preheating system in sequence. After separation, it enters the next stage preheater or the roasting furnace.

[0015] After step c), the process further includes: introducing the incompletely separated fine petroleum coke along with the flue gas into a ceramic filter separator using inert gas backflushing for fine separation; the separated flue gas contains a high concentration of volatiles and is sent to a combustion furnace for combustion.

[0016] The online gas analyzer is a tunable diode laser absorption spectrometer gas analyzer, used to monitor the concentration of O2 and CO components in real time, and to feed the monitoring data back to the control system to adjust the combustion air volume, fuel volume or raw material feed volume.

[0017] The roasting temperature in the fluidized bed roasting furnace is 800-1350℃, and the residence time of the material in the fluidized bed roasting furnace is 3-15 seconds.

[0018] In step e), the material air cooler uses air as a cooling medium to indirectly exchange heat with the high-temperature calcined coke, and the heated air is sent into the fluidized suspension roasting furnace as a combustion or roasting gas.

[0019] The calcination system used in the aforementioned method for calcining petroleum coke in a fluidized suspension includes:

[0020] A multi-stage preheating system for countercurrent preheating of petroleum coke feedstock;

[0021] A fluidized suspension roasting furnace, the inlet of which is connected to the outlet of the multi-stage preheating system, is used to enable the preheated petroleum coke to form a fluidized suspension state in a high-temperature gas flow for rapid roasting.

[0022] A main solid-gas separation device, the inlet of which is connected to the outlet of the roasting furnace, is used to separate the high-temperature material after roasting from the high-temperature flue gas;

[0023] A flue gas recirculation and control loop is provided, which guides a portion of the high-temperature flue gas separated by the main solid-gas separator back to the fluidized bed roaster and / or the multi-stage preheating system. An online gas analyzer is also provided on the loop.

[0024] A cooling system, the inlet of which is connected to the material outlet of the main solid-gas separation device, the cooling system comprising a material air cooler and a material water cooler connected in sequence;

[0025] A combustion furnace, the inlet of which is connected to the flue gas outlet of the multi-stage preheating system or fine separation device;

[0026] A flue gas purification system is connected to the outlet of the combustion furnace. The system includes a quenching device, an SCR denitrification device, a flue gas cooler, and a wet desulfurization tower connected in sequence.

[0027] It also includes a special ceramic ultrafine separator, which is located on the flue gas outlet path of the main solid-gas separation device and is equipped with an inert gas backflushing device, and its flue gas outlet is connected to the inlet of the combustion furnace.

[0028] The online gas analyzer is a tunable diode laser absorption spectrometer gas analyzer, and the system also includes a central control system, which is connected to the online gas analyzer and the actuators that control the supply of combustion air, fuel and raw materials to form a closed-loop control.

[0029] The hot air outlet of the material air cooler is connected to the bottom air inlet of the fluidized suspension roasting furnace via a pipe to deliver the preheated air during the cooling process to the roasting furnace.

[0030] The online gas analyzer is a tunable diode laser absorption spectroscopy (TDLAS) gas analyzer, used to monitor the concentration of components such as O2 and CO in real time, and to feed the monitoring data back to the control system to adjust the combustion air volume, fuel volume or raw material feed volume.

[0031] By utilizing fluidization technology, micron-sized petroleum coke particles are suspended in a high-temperature gas flow, greatly increasing the gas-solid contact area and heat and mass transfer efficiency, achieving rapid calcination within seconds. At the same time, through multi-stage countercurrent heat exchange and flue gas recirculation technology, the system achieves tiered utilization of internal heat and precise control of the calcination atmosphere, thereby achieving high efficiency, energy saving, high yield, and low cost.

[0032] The specific calcination method and system connection relationship are as follows:

[0033] 1. Raw material supply and multi-stage countercurrent preheating:

[0034] Petroleum coke powder stored in the feed silo is conveyed into the Venturi unit. Here, the material encounters hot flue gas from the subsequent preheater, is carried by the gas flow and preheated. Subsequently, the gas-solid mixture passes through a primary, secondary, tertiary, and quaternary preheater in sequence. Through four stages of countercurrent preheating, the material temperature is progressively increased before entering the fluidized bed roaster.

[0035] 2. Flow suspension roasting and high-temperature separation:

[0036] Preheated petroleum coke enters a fluidized bed roaster. Inside the furnace, high-temperature gas flow from the bottom lifts the petroleum coke particles, creating a suspension. In this state, the material comes into full contact with the high-temperature flue gas, and at a temperature of 800-1350℃, deep removal of volatiles is achieved in just 3-15 seconds. The roasted high-temperature calcined coke then enters a roasting separator along with the flue gas, where most of the material is separated and enters the subsequent cooling system.

[0037] 3. Material cooling and waste heat recovery:

[0038] The high-temperature petroleum coke (800℃-1000℃) separated from the roasting separator enters the material air cooler. An air-cooling fan introduces cold air, and the cold air and high-temperature petroleum coke exchange heat indirectly within the material air cooler. The temperature of the high-temperature petroleum coke is reduced to below 600℃, while the air is heated. This heated air mixes with a portion of the hot flue gas from the combustion furnace outlet and enters the fluidized bed roaster together, serving as the heat source and fluidizing gas required for roasting the material, thus achieving efficient recovery and utilization of the sensible heat of the calcined coke.

[0039] The petroleum coke exiting the air cooler then enters the water cooler, where it undergoes indirect heat exchange with the cooling water, ultimately reducing its temperature to below 80°C, thus becoming the finished product.

[0040] 4. Flue gas treatment and heat recovery:

[0041] The flue gas from the calcination separator and each stage of preheaters is combined and then enters a special ceramic ultrafine separator for fine dust removal. This separator uses nitrogen generated by a nitrogen generator for backflushing and cleaning. The recovered fine powder material can be returned to the system, while providing inert protection for high-temperature fine powder.

[0042] After passing through a special ceramic ultrafine separator, the flue gas, containing a high concentration of volatile organic compounds, is sent to a combustion furnace for combustion. The combustion of these volatile compounds in the furnace releases a large amount of heat, resulting in high-temperature flue gas at the furnace outlet, ranging from 600°C to 1000°C.

[0043] The high-temperature flue gas is divided into two paths: one path enters the bottom of the fluidized bed roaster to recover the heat generated by the combustion of volatiles in the flue gas; the other path enters the subsequent flue gas purification system.

[0044] 5. Flue gas purification and emission:

[0045] The flue gas entering the purification system first passes through a quenching device, rapidly reducing its temperature to below 300℃ to meet the optimal operating temperature requirements of the subsequent SCR denitrification unit and suppress the formation of pollutants such as dioxins. The cooled flue gas then enters the SCR denitrification unit to reduce the concentration of nitrogen oxides. Subsequently, the flue gas enters a flue gas cooler, further reducing its temperature to 120℃-150℃. Finally, the flue gas enters a wet desulfurization tower to remove high concentrations of sulfur dioxide. The purified, compliant flue gas is ultimately discharged through a chimney by an induced draft fan.

[0046] 6. Online monitoring and closed-loop control system:

[0047] The system deploys four TDLAS concentration analyzers at key nodes to monitor the gas entering the roasting furnace, the atmosphere inside the roasting furnace, the circulating flue gas entering the preheating system, and the composition of the final emitted flue gas. By linking with the DCS system, it achieves closed-loop control of combustion air volume, fuel volume, and raw material feed volume, accurately manages the roasting atmosphere, and effectively suppresses oxidation loss.

[0048] The No. 1 analyzer monitors the oxygen concentration of the mixed gas entering the bottom of the calcining furnace and ensures combustion efficiency by adjusting the air volume of the make-up air fan.

[0049] The No. 2 analyzer monitors the oxygen concentration at the outlet of the lower combustion chamber of the roasting furnace and controls the oxygen content of the flue gas after combustion by adjusting the amount of fuel (such as natural gas).

[0050] The No. 3 analyzer monitors the oxygen concentration of the circulating flue gas entering the Venturi unit. This is the key point for controlling the atmosphere of the entire preheating and roasting system. By adjusting the petroleum coke feed rate and total air volume in a coordinated manner, the oxygen is controlled at an extremely low level (such as 0.1%-3%), thereby achieving effective protection of the petroleum coke.

[0051] Analyzer #4 monitors the composition of the final emitted flue gas.

[0052] The real-time data from these analyzers is sent to the DCS central control system, which automatically adjusts the relevant actuators (fans, valves, feeders, etc.) to form a closed-loop control, thereby achieving precise management of the roasting atmosphere and effectively suppressing oxidation loss.

[0053] Compared with the prior art, the beneficial effects of the present invention are:

[0054] (1) This invention adopts the principle of fluidized suspension roasting, which shortens the roasting time of petroleum coke from tens of hours in traditional kilns to seconds, thereby increasing production efficiency by orders of magnitude. More importantly, the system constructs two highly efficient heat recovery closed loops: first, the sensible heat of the high-temperature calcined coke is recovered through the material air cooler, and the generated hot air is directly sent into the roasting furnace as combustion / roasting gas; second, the volatile matter rich in the flue gas is sent into the combustion furnace, where its chemical energy is converted into high-grade heat energy, and the generated high-temperature flue gas is recycled back to the roasting furnace. This dual recovery and utilization of "sensible heat + chemical energy" realizes the deep self-circulation of system energy, greatly reduces the consumption of purchased fuel, and has significant energy consumption advantages.

[0055] (2) By setting up an online laser gas analyzer (TDLAS) at key nodes and combining it with a DCS system to form a closed-loop control, this invention achieves precise control of the oxygen content in the atmosphere of the calcination and preheating zones, maintaining it at an extremely low level that inhibits oxidation. Simultaneously, the use of a special ceramic ultrafine separator supplemented by nitrogen inert backflushing effectively avoids the oxidation and burn-off of high-temperature fine powder materials. These two measures together ensure that the product yield is much higher than that of traditional processes. The material is heated uniformly, rapidly, and fully in a suspended state, which can stably control the volatile matter in the calcined coke to below 1%, resulting in good product quality uniformity and excellent performance.

[0056] (3) This invention transforms the volatile organic compounds emitted as waste gas in traditional processes into valuable internal circulation fuel, which is then fully combusted at high temperatures in a combustion furnace. This not only "turns waste into treasure" but also solves the problem of VOCs emission at the source. The flue gas after combustion then undergoes a deep purification process of "rapid cooling + SCR denitrification + flue gas cooling + wet desulfurization," ensuring that the emission concentrations of pollutants such as nitrogen oxides and sulfur dioxide meet or exceed environmental emission standards. Therefore, this invention not only significantly reduces production costs through extremely low energy consumption and extremely high yield but also provides a complete and efficient environmental protection solution. The entire system is highly automated and operates stably and reliably. Attached Figure Description

[0057] Figure 1 This is a schematic diagram of the calcination system for the fluidized suspension roasting of petroleum coke according to the present invention;

[0058] In the diagram: 1. Raw material silo; 2. Venturi unit; 3. Primary preheater; 4. Secondary preheater; 5. Tertiary preheater; 6. Quaternary preheater; 7. Flow suspension roasting furnace; 8. Roasting separator; 9. Material air cooler; 10. Air-cooled fan; 11. Material water cooler; 12. Special ceramic ultrafine separator; 13. Exhaust fan; 14. Combustion furnace; 15. Quenching device; 16. SCR denitrification device; 17. Flue gas cooler; 18. Wet desulfurization tower; 19. Nitrogen generator; 20. No. 1 oxygen / carbon monoxide TDLAS concentration analyzer; 21. No. 2 oxygen / carbon monoxide TDLAS concentration analyzer; 22. No. 3 oxygen / carbon monoxide TDLAS concentration analyzer; 23. No. 4 oxygen / carbon monoxide TDLAS concentration analyzer. Detailed Implementation

[0059] The technical solutions of the present invention will be clearly and completely described below with reference to the embodiments and accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0060] This invention provides an efficient and low-cost calcination method for petroleum coke in a fluidized suspension roasting furnace, including steps such as multi-stage countercurrent preheating of petroleum coke raw materials, rapid roasting in a fluidized suspension roasting furnace, high-temperature solid-gas separation, flue gas recirculation and closed-loop atmosphere control, and multi-stage countercurrent cooling and heat recovery.

[0061] This invention also provides a high-efficiency, low-cost calcination system for fluidized suspension roasting of petroleum coke. Please refer to [link to relevant documentation]. Figure 1 The system includes a raw material feeding system, a multi-stage preheating system, a multi-stage cooling system, a flue gas recirculation and control loop, and a finished product collection system.

[0062] In this invention, the core principle of the calcination method lies in utilizing fluidization technology to suspend petroleum coke particles with a preferred particle size of 1-100 μm under the action of a high-temperature airflow. This significantly increases the gas-solid heat and mass transfer efficiency, achieving rapid calcination within seconds. The entire system achieves efficient, tiered energy utilization through multi-stage countercurrent heat exchange.

[0063] In this invention, the raw material preheating process is as follows: petroleum coke powder stored in the raw material silo 1 enters the Venturi device 2, mixes with high-temperature flue gas, and is then carried by the flue gas through a multi-stage preheating system. The material and the hot flue gas are in countercurrent contact, the material temperature increases step by step, while the flue gas temperature decreases step by step, thereby maximizing the recovery of sensible heat in the flue gas and significantly reducing system energy consumption.

[0064] In this invention, the rapid calcination process specifically includes:

[0065] Raw material supply and multi-stage countercurrent preheating:

[0066] Petroleum coke powder stored in raw material silo 1 enters the Venturi unit 2 via a conveying system. Here, the material encounters hot flue gas from a subsequent preheater, is carried by the gas flow, and is preheated. Subsequently, the gas-solid mixture passes sequentially through a primary preheater 3, a secondary preheater 4, a tertiary preheater 5, and a quaternary preheater 6. Through four stages of countercurrent preheating, the material temperature is progressively increased before entering the fluidized bed roaster 7.

[0067] Flow suspension roasting and high-temperature separation:

[0068] The preheated petroleum coke enters the fluidized bed roaster 7. Inside the furnace, the petroleum coke particles are blown up by a high-temperature airflow introduced from the bottom, forming a suspension. In this state, the material is in full contact with the high-temperature flue gas, and at a temperature of 800-1350℃, deep removal of volatiles can be completed in just 3-15 seconds. The roasted high-temperature calcined coke enters the roasting separator 8 along with the flue gas, where most of the material is separated and enters the subsequent cooling system.

[0069] Material cooling and waste heat recovery:

[0070] The high-temperature petroleum coke (800℃-1000℃) separated from the roasting separator 8 enters the material air cooler 9. Cold air is introduced by the air-cooling fan 10, and the cold air and high-temperature petroleum coke exchange heat indirectly in the material air cooler 9. The temperature of the high-temperature petroleum coke is reduced to below 600℃, while the air is heated. This heated air mixes with a portion of the hot flue gas from the outlet of the combustion furnace 14 and enters the fluidized bed roasting furnace 7 together, serving as the heat source and fluidizing gas required for roasting the material, thus achieving efficient recovery and utilization of the sensible heat of the calcined coke.

[0071] The petroleum coke exiting the material air cooler 9 then enters the material water cooler 11, where the petroleum coke and cooling water exchange heat indirectly, ultimately reducing the temperature of the petroleum coke to below 80°C, thus becoming the finished product.

[0072] Flue gas treatment and heat recovery:

[0073] The flue gas from the calcination separator 8 and each stage of preheaters is combined and then enters the special ceramic ultrafine separator 12 for fine dust removal. This separator uses nitrogen generated by the nitrogen generator 19 for backflushing and dust removal. The recovered fine powder material can be returned to the system, while providing inert protection for high-temperature fine powder.

[0074] After passing through the special ceramic ultrafine separator 12, the flue gas, containing a high concentration of volatile organic compounds, is sent to the combustion furnace 14 for combustion. The combustion of volatiles in the combustion furnace 14 releases a large amount of heat, resulting in high-temperature flue gas at the furnace outlet at 600℃-1000℃.

[0075] The high-temperature flue gas is divided into two paths: one path enters the bottom of the fluidized bed roaster 7 to recover the heat generated by the combustion of volatiles in the flue gas; the other path enters the subsequent flue gas purification system.

[0076] Flue gas purification and emission:

[0077] The flue gas entering the purification system first passes through a quenching device 15, rapidly reducing its temperature to below 300℃ to meet the optimal operating temperature requirements of the subsequent SCR denitrification unit 16 and suppress the formation of pollutants such as dioxins. The cooled flue gas then enters the SCR denitrification unit 16 to reduce the concentration of nitrogen oxides. Subsequently, the flue gas enters a flue gas cooler 17, where its temperature is further reduced to 120℃-150℃. Finally, the flue gas enters a wet desulfurization tower 18 to remove high concentrations of sulfur dioxide. The purified, compliant flue gas is ultimately discharged through a chimney by an induced draft fan 13.

[0078] Online monitoring and closed-loop control system:

[0079] The system deploys four TDLAS concentration analyzers at key nodes to monitor the concentrations of O2 and CO in the gas entering the roasting furnace, the gas inside the roasting furnace, the gas in the lower part of the Venturi, and the final exhaust gas. Through linkage with the DCS system, it achieves closed-loop control of combustion air volume, fuel quantity, and raw material feed rate, precisely managing the roasting atmosphere and effectively suppressing oxidation loss. To achieve precise control of the roasting atmosphere, the system deploys online laser gas analyzers at the four key nodes:

[0080] The oxygen / carbon monoxide TDLAS concentration analyzer 20 is installed at the bottom of the main air inlet pipe of the flow suspension roasting furnace 7 to monitor the oxygen concentration of the mixed gas entering the furnace.

[0081] The oxygen / carbon monoxide TDLAS concentration analyzer 21 is installed in the lower combustion zone of the fluidized bed roaster 7 to monitor the oxygen concentration of the flue gas after combustion. Its data is used to regulate the supply of fuel (such as natural gas) in a closed loop.

[0082] The #3 oxygen / carbon monoxide TDLAS concentration analyzer 22 is installed on the preheated flue gas pipeline entering the Venturi unit 2 to monitor the total atmospheric oxygen concentration entering the entire preheating roasting system. This is a key control point to prevent material oxidation, and its data is used to adjust the raw material feeding rate in a coordinated manner.

[0083] The 4# oxygen / carbon monoxide TDLAS concentration analyzer 23 is installed at the outlet of the special ceramic ultrafine separator 12 to monitor the composition of the flue gas about to enter the purification system. It can be used as a basis for judging the overall operation status of the system and as the final monitoring before emission.

[0084] In summary, through the organic combination and synergistic operation of the above-mentioned functional units, the present invention constitutes a complete, efficient, energy-saving, environmentally friendly and highly automated petroleum coke calcination system.

[0085] The calcination method and system provided by this invention features a compact process flow design, closed-loop energy utilization, and a high level of automation control. Compared with traditional processes such as pot furnaces and rotary kilns in the prior art, this invention completely changes the heat transfer method and solves technical problems such as long calcination cycles, high energy consumption, and severe oxidation loss.

[0086] The fluidized bed roasting method and system provided by this invention, through the synergistic effect of fluidized bed roasting, multi-stage waste heat recovery, and precise atmosphere control, can stably control the volatile matter content of the product to below 1%, while achieving high product yield and uniform quality. This technology can be widely applied to the industrial preparation of calcined coke for prebaked anodes, high-purity carbon materials, and related carbon raw materials, offering significant economic and environmental benefits.

[0087] Furthermore, the system provided by this invention has a high degree of automation. It can centrally monitor and automatically adjust key parameters such as temperature, pressure, flow rate and atmosphere through a DCS central control system, which reduces the intensity of manual operation and ensures the stability of the production process and the consistency of product quality.

[0088] To further illustrate the present invention, the following embodiments provide a detailed description. The equipment used in the following embodiments may be specialized equipment customized according to the present invention, or a combination of commercially available standard equipment.

[0089] Example 1

[0090] like Figure 1 As shown, a highly efficient and low-cost calcination method and system for fluidized suspension roasting of petroleum coke is described, and its workflow is as follows:

[0091] (1) Petroleum coke powder with a particle size of 1-35μm and a volatile content of 8%-13% is fed into raw material silo 1.

[0092] (2) The petroleum coke raw material obtained in step (1) is fed into a multi-stage preheating unit. The raw material flows through each stage of the preheater in sequence to achieve staged temperature increase: the temperature of the first stage preheater 3 is set at 480℃, the temperature of the second stage preheater 4 is set at 420℃, the temperature of the third stage preheater 5 is set at 750℃, and the temperature of the fourth stage preheater 6 is set at 895℃.

[0093] (3) Control the oxygen concentration in the No. 1 oxygen / carbon monoxide TDLAS concentration analyzer 20 at 13.5%, the oxygen concentration in the No. 2 oxygen / carbon monoxide TDLAS concentration analyzer 21 at 8.0%, the oxygen concentration in the No. 3 oxygen / carbon monoxide TDLAS concentration analyzer 22 at 0.85%, and the oxygen concentration in the No. 4 oxygen / carbon monoxide TDLAS concentration analyzer 23 at 1.5%;

[0094] (4) The petroleum coke material obtained in step (2) is fed into the fluidized suspension roasting furnace 7 and roasted in an atmosphere of N2, H2O (g), CO2 and micro-oxygen. The air velocity of the fluidized suspension roasting furnace 7 is set to 3m / s to form a gas-solid two-phase flow environment. The petroleum coke raw material is roasted in the fluidized suspension roasting furnace for 5-10s, so that the petroleum coke raw material is initially roasted at 1100℃. Then the roasted material is fed into the roasting separator 8 to separate the flue gas and the material.

[0095] (5) The roasted petroleum coke is sent to the material air cooler 9 for cooling. The material temperature drops to about 580°C, and the generated hot air is sent to the flow suspension roasting furnace 7. Then the material enters the material water cooler 11. Through indirect water cooling, the temperature of the discharged material is 65°C, and the volatile matter of the petroleum coke is 0.8%.

[0096] (6) The flue gas containing volatiles from the special ceramic ultrafine separator 12 enters the combustion furnace 14 for combustion. The outlet flue gas temperature is 950°C. Part of it is sent to the fluidized suspension roasting furnace 7, and the other part is cooled to 280°C by the quenching device 15 and enters the SCR denitrification device 16 for denitrification. After being cooled to 140°C by the flue gas cooler 17, it enters the wet desulfurization tower 18 for desulfurization and is then discharged.

[0097] Example 2

[0098] like Figure 1 As shown, a highly efficient and low-cost calcination method and system for fluidized suspension roasting of petroleum coke is described, and its workflow is as follows:

[0099] (1) Petroleum coke powder with a particle size of 1-35μm and a volatile content of 8%-13% is fed into raw material silo 1.

[0100] (2) The petroleum coke raw material obtained in step (1) is fed into a multi-stage preheating unit. The raw material flows through each stage of the preheater in sequence to achieve staged temperature increase: the temperature of the first stage preheater 3 is set at 500℃, the temperature of the second stage preheater 4 is set at 450℃, the temperature of the third stage preheater 5 is set at 780℃, and the temperature of the fourth stage preheater 6 is set at 920℃.

[0101] (3) Control the oxygen concentration in the No. 1 oxygen / carbon monoxide TDLAS concentration analyzer 20 at 15%, the oxygen concentration in the No. 2 oxygen / carbon monoxide TDLAS concentration analyzer 21 at 10.0%, the oxygen concentration in the No. 3 oxygen / carbon monoxide TDLAS concentration analyzer 22 at 0.1%, and the oxygen concentration in the No. 4 oxygen / carbon monoxide TDLAS concentration analyzer 23 at 1.8%;

[0102] (4) The petroleum coke material obtained in step (2) is fed into the fluidized suspension roasting furnace 7 and roasted in an atmosphere of N2, H2O(g), CO2 and micro-oxygen. The air velocity of the fluidized suspension roasting furnace 7 is set to 3.2m / s to form a gas-solid two-phase flow environment. The petroleum coke raw material is roasted in the fluidized suspension roasting furnace for 3-9s, so that the petroleum coke raw material is initially roasted at 1150℃. Then the roasted material is fed into the roasting separator 8 to separate the flue gas and the material.

[0103] (5) The roasted petroleum coke is sent to the material air cooler 9 for cooling. The material temperature drops to about 590°C, and the generated hot air is sent to the flow suspension roasting furnace 7. Then the material enters the material water cooler 11. Through indirect water cooling, the temperature of the discharged material is 80°C, and the volatile matter of the petroleum coke is 0.68%.

[0104] (6) The flue gas containing volatiles from the special ceramic ultrafine separator 12 enters the combustion furnace 14 for combustion. The outlet flue gas temperature is 980°C. Part of it is sent to the fluidized suspension roasting furnace 7, and the other part is cooled to 290°C by the quenching device 15 and enters the SCR denitrification device 16 for denitrification. After being cooled to 150°C by the flue gas cooler 17, it enters the wet desulfurization tower 18 for desulfurization and is then discharged.

[0105] Example 3

[0106] like Figure 1 As shown, a highly efficient and low-cost calcination method and system for fluidized suspension roasting of petroleum coke is described, and its workflow is as follows:

[0107] (1) Petroleum coke powder with a particle size of 1-35μm and a volatile content of 8%-13% is fed into raw material silo 1.

[0108] (2) The petroleum coke raw material obtained in step (1) is fed into a multi-stage preheating unit. The raw material flows through each stage of the preheater in sequence to achieve staged temperature increase: the temperature of the first stage preheater 3 is set at 550℃, the temperature of the second stage preheater 4 is set at 480℃, the temperature of the third stage preheater 5 is set at 820℃, and the temperature of the fourth stage preheater 6 is set at 950℃.

[0109] (3) Control the oxygen concentration in the No. 1 oxygen / carbon monoxide TDLAS concentration analyzer 20 at 13%, the oxygen concentration in the No. 2 oxygen / carbon monoxide TDLAS concentration analyzer 21 at 8.0%, the oxygen concentration in the No. 3 oxygen / carbon monoxide TDLAS concentration analyzer 22 at 0.1%, and the oxygen concentration in the No. 4 oxygen / carbon monoxide TDLAS concentration analyzer 23 at 0.5%;

[0110] (4) The petroleum coke material obtained in step (2) is fed into the fluidized suspension roasting furnace 7 and roasted in an atmosphere of N2, H2O(g), CO2 and micro-oxygen. The air velocity of the fluidized suspension roasting furnace 7 is set to 2.8 m / s to form a gas-solid two-phase flow environment. The material is roasted in the fluidized suspension roasting furnace for 5-12 seconds, so that the petroleum coke raw material is initially roasted at 1200℃. Then the roasted material is fed into the roasting separator 8 to separate the flue gas and the material.

[0111] (5) The roasted petroleum coke is sent to the material air cooler 9 for cooling. The material temperature drops to about 600°C or below, and the generated hot air is sent to the fluid suspension roasting furnace 7. Then the material enters the material water cooler 11. Through indirect water cooling, the temperature of the discharged material is 80°C and the volatile matter of the petroleum coke is 0.55%.

[0112] (6) The flue gas containing volatiles from the special ceramic ultrafine separator 12 enters the combustion furnace 14 for combustion. The outlet flue gas temperature is 1000℃. Part of it is sent to the fluidized suspension roasting furnace 7, and the other part is cooled to below 300℃ by the quenching device 15 and enters the SCR denitrification device 16 for denitrification. After being cooled to 145℃ by the flue gas cooler 17, it enters the wet desulfurization tower 18 for desulfurization and is then discharged.

[0113] Comparative Example 1

[0114] An intermittent pot-type calcining furnace is used, with the furnace body constructed of refractory bricks and equipped with a gas heating system and a simple temperature monitoring device.

[0115] The pretreated raw petroleum coke was evenly loaded into the furnace jar to a height of 3800 mm, ensuring uniform air permeability of the material layer. A gradient heating mode was adopted: the temperature was raised from room temperature to 300℃ at a rate of 50℃ / h and held for 2 hours (dehydration stage); the temperature was raised from 300℃ to 800℃ at a rate of 80℃ / h and held for 4 hours (initial volatile matter precipitation stage); the temperature was raised from 800℃ to 1250℃ at a rate of 60℃ / h and held for 12 hours (deep roasting stage). After roasting, the material was discharged after natural cooling to room temperature. The entire roasting cycle was 72 hours. Natural ventilation was used during the roasting process to control the oxygen content in the furnace to 3-5%.

[0116] Technical drawbacks: long roasting cycle and low production efficiency; low degree of automation, relying on manual experience to control temperature, uneven temperature distribution in the furnace, and easy to cause under-burning and over-burning; high energy consumption and low gas utilization rate; intermittent operation, high labor intensity, and poor product quality stability; easy coking on the inner wall of the furnace, difficult to clean and maintain, and limited equipment lifespan.

[0117] Comparative Example 2

[0118] It adopts a semi-continuous tunnel kiln, equipped with an electric heating system and a forced ventilation device, and is divided into a preheating section, a roasting section and a cooling section.

[0119] The pretreated raw petroleum coke is loaded into a refractory sagger, which is placed on the kiln car platform and moved slowly with the kiln car. The preheating section temperature is 300-650℃, the moving distance is 12m, and the residence time is 24h, to complete dehydration and volatile matter release. The roasting section temperature is 1260℃, the moving distance is 16m, and the residence time is 32h, to complete deep roasting. The cooling section temperature is ≤250℃, the moving distance is 12m, and the residence time is 24h, using forced ventilation cooling. During the roasting process, the oxygen content in the furnace is controlled at 3-5%.

[0120] Technical drawbacks: long roasting cycle (80h), extremely low production efficiency; high energy consumption, large electricity consumption, and high operating costs; poor roasting uniformity, large temperature differences in different areas of the kiln, easy to produce under-burned material, and poor product quality stability; semi-continuous operation, high labor intensity, and low degree of automation; mediocre flue gas treatment effect and poor environmental performance; large equipment footprint, slow heating rate, low heat utilization rate, and difficult maintenance.

[0121] The test data for Examples 1-3 and Comparative Examples 1-2 are shown in Table 1.

[0122] Table 1: Test data of Examples 1-3 and Comparative Examples 1-2

[0123]

[0124] Calcination time refers to the time it takes for materials to enter and exit the system.

[0125] As shown in Table 1, the calcination time in the embodiments of the present invention is only 3-4 minutes, far shorter than the 35 hours of Comparative Example 1 and the 28 hours of Comparative Example 2, demonstrating the improvement in heat and mass transfer efficiency of the fluidized suspension calcination technology. The volatile matter content in the embodiments is stable at 0.55%-0.80%, all below 1%, which is better than the 0.82%-0.89% of the comparative examples, indicating that the present invention achieves more thorough and stable volatile matter removal. The yield of the embodiments is between 89.9%-91.2%, far higher than the 82.6%-85.3% of the comparative examples, indicating that the present invention effectively suppresses oxidation loss and improves material utilization through atmosphere control and inert protection. The unit energy consumption of the embodiments is 125-131 kgce / t, a decrease of approximately 36%-38% compared to the 198-206 kgce / t of the comparative examples, demonstrating the high efficiency of waste heat recovery and energy cascade utilization of the system. The product from the example exhibits uniform particle size, high activity, and well-developed microcrystals. Its true density and resistivity are superior to or close to those of the comparative example, demonstrating that the present invention maintains excellent product performance while ensuring high efficiency. In summary, the present invention significantly outperforms traditional processes in terms of calcination efficiency, energy consumption control, product yield, and quality, possessing significant technological advancement and industrial application value.

Claims

1. A method for calcining petroleum coke in a fluidized suspension, characterized in that, Includes the following steps: a) The petroleum coke feedstock is fed into a multi-stage preheating system heated by flue gas for countercurrent preheating; b) The preheated petroleum coke is fed into a fluid suspension roasting furnace (7) and rapidly roasted under the action of high-temperature airflow to form a fluid suspension state. c) Separate the high-temperature roasted material from the high-temperature flue gas; d) The high-temperature flue gas separated in step c) is recycled to the fluidized suspension roasting furnace (7) and the multi-stage preheating system, and the oxygen content in the atmosphere in the roasting furnace is monitored and controlled in a closed loop using an online gas analyzer to suppress the oxidation loss of petroleum coke. e) The high-temperature calcined coke separated in step c) is sent to a cooling system consisting of a material air cooler (9) and a material water cooler (11) for cooling, and the heat released in the material air cooler (9) is recovered. After step c), the process further includes: introducing the incompletely separated fine petroleum coke along with the flue gas into a ceramic filter separator using inert gas backflushing for fine separation, the separated flue gas containing high concentrations of volatiles is sent to a combustion furnace (14) for combustion. The online gas analyzer is a tunable diode laser absorption spectroscopy gas analyzer, used to monitor the concentration of O2 and CO components in real time, and to feed the monitoring data back to the control system to adjust the combustion air volume, fuel volume or raw material feed volume. In step e), the material air cooler (9) uses air as a cooling medium to indirectly exchange heat with the high-temperature calcined coke. The heated air is sent into the fluidized suspension roasting furnace (7) as a combustion or roasting gas.

2. The calcination method for petroleum coke in fluidized suspension roasting according to claim 1, characterized in that, The petroleum coke feedstock is carried by flue gas and passes through each stage of the multi-stage preheating system in sequence. After separation, it enters the next stage preheater or the roasting furnace.

3. The calcination method for petroleum coke in fluidized suspension roasting according to claim 1, characterized in that, The roasting temperature in the fluidized suspension roasting furnace (7) is 800-1350℃, and the residence time of the material in the fluidized suspension roasting furnace is 3-15 seconds.

4. A calcination system used in the calcination method for the fluidized bed roasting of petroleum coke according to any one of claims 1-3, characterized in that, include: A multi-stage preheating system for countercurrent preheating of petroleum coke feedstock; A fluid suspension roasting furnace (7) is connected at its inlet to the outlet of the multi-stage preheating system, which is used to enable the preheated petroleum coke to form a fluid suspension state in the high-temperature gas flow for rapid roasting. A main solid-gas separation device, the inlet of which is connected to the outlet of the roasting furnace, is used to separate the high-temperature material after roasting from the high-temperature flue gas; A flue gas recirculation and control loop is provided, which guides a portion of the high-temperature flue gas separated by the main solid-gas separation device back to the fluidized suspension roasting furnace (7) and the multi-stage preheating system. An online gas analyzer is also provided on the loop. A cooling system, the inlet of which is connected to the material outlet of the main solid-gas separation device, the cooling system comprising a material air cooler (9) and a material water cooler (11) connected in sequence. A combustion furnace (14) has its inlet connected to the flue gas outlet of the multi-stage preheating system or fine separation device; A flue gas purification system is connected to the outlet of the combustion furnace (14). The system includes a quenching device, an SCR denitrification device (16), a flue gas cooler (17), and a wet desulfurization tower (18) connected in sequence.

5. The calcination system according to claim 4, characterized in that, It also includes a special ceramic ultrafine separator (12), which is located on the flue gas outlet path of the main solid-gas separation device and is equipped with an inert gas backflushing device, and its flue gas outlet is connected to the inlet of the combustion furnace (14).

6. The calcination system according to claim 4, characterized in that, The online gas analyzer is a tunable diode laser absorption spectrometer gas analyzer, and the system also includes a central control system, which is connected to the online gas analyzer and the actuators that control the supply of combustion air, fuel and raw materials to form a closed-loop control.

7. The calcination system according to claim 4, characterized in that, The hot air outlet of the material air cooler (9) is connected to the bottom air inlet of the fluidized suspension roasting furnace (7) via a pipe to deliver the preheated air during the cooling process to the roasting furnace.

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