Metallurgy biological coke preparation system and method based on graded utilization of biological oil

Abstract

The invention provides a metallurgical bio-coke preparation system and method based on bio-oil graded utilization. The system comprises a first pyrolyzing furnace, a cyclone separator, a first condensing device, a second condensing device, a pickling device, a granulating device, a first conveyor, a second pyrolyzing furnace, a coke oven and a second conveyor, an outlet of the first pyrolyzing furnace is connected to an inlet of the cyclone separator, and a solid phase sequentially passes through the cyclone separator, the pickling device, the granulating device, the first conveyor, the second pyrolyzing furnace, the coke oven and the second conveyor; a gas phase and a liquid phase sequentially pass through the cyclone separator and the condensing devices, a heavy oil outlet of the first condensing device is connected to the granulating device, and a light oil outlet of the second condensing device is connected to the pickling device. According to the system and the method, through graded utilization of the bio-oil, the characteristics of the metallurgical bio-coke are autonomously regulated and controlled, the utilization rate of biomass is increased, and meanwhile extra cost and risks caused by a supply chain are avoided.

Description

Technical Field

[0001] The invention relates to the technical field of metallurgy, and in particular to a metallurgical bio-coke preparation system and method based on bio-oil graded utilization. Background Art

[0002] The steel industry is one of the largest industrial carbon dioxide emission industries. In my country, the long process steelmaking process accounts for about 9.2% of my country's total carbon emissions and about 15% of the total carbon emissions in the industrial field. As the main steelmaking route, the blast furnace-converter process has high energy consumption and high carbon emissions in the sintering, coking and blast furnace processes. Its carbon emissions are particularly prominent, accounting for more than 75% of the carbon emissions of the entire steel industry, showing the important challenges faced by the blast furnace process in energy conservation and emission reduction. The use of biomass energy utilization technology can reduce carbon emissions from long process processes by 30-40%, which has attracted widespread attention to biomass substitution for fossil energy. However, unlike mature applications in power generation and heating industries, the application of biomass in the steel industry is still in the technical research stage, and there are few engineering demonstrations. In view of this, conducting research on biomass energy utilization for the steel industry has extremely high research significance and broad application prospects.

[0003] Biomass resources, as a valuable natural asset second only to traditional fossil energy in terms of reserves, are widely distributed and diverse, including crop residues, forestry waste, urban domestic waste, and aquatic plants. Biomass can be introduced into blast furnaces as low-carbon fuels and reducing agents in three forms, including biochar, bio-oil, and biomass-derived syngas. However, due to economic and operability reasons, previous research has mainly focused on injecting biocoke into blast furnaces. Biocoke can be widely used in many processes such as coke production (coking with coal), tuyere injection, iron ore sintering, and carbon composite pelletizing. However, unlike traditional coal coke, the high alkali metal content, low strength, high reactivity, and high volatile content of biocoke limit the addition ratio of biocoke. For example, the addition ratio in coke should not exceed 2-10wt.%, and the addition ratio in sintering should not exceed 40wt.%, which greatly reduces the carbon reduction potential of biomass energy. Therefore, it is urgent to develop new metallurgical biocoke performance control technologies to meet the requirements for the characteristics of low-carbon fuels and reducing agents in different process steps. Summary of the invention

[0004] The present invention provides a metallurgical bio-coke preparation system and method based on bio-oil graded utilization, which are used to solve the defects of high alkali metal content, low strength and high volatile matter content of bio-coke in the prior art.

[0005] The present invention provides a metallurgical bio-coke preparation system based on bio-oil graded utilization, comprising a first pyrolysis furnace, a cyclone separator, a first condensation device, a second condensation device, a pickling device, a granulation device, a first conveyor, a second pyrolysis furnace, a coke oven, and a second conveyor;

[0006] The inlet of the first pyrolysis furnace is used to input biomass fuel, the outlet of the first pyrolysis furnace is connected to the inlet of the cyclone separator, the solid phase outlet of the cyclone separator is connected to the solid phase inlet of the pickling device, the solid phase outlet of the pickling device is connected to the solid phase inlet of the granulation device, the outlet of the granulation device is connected to the inlet of the first conveyor, the outlet of the first conveyor is connected to the solid phase inlet of the second pyrolysis furnace, the solid phase outlet of the second pyrolysis furnace is connected to the solid phase inlet of the coke oven, the solid phase outlet of the coke oven is connected to the inlet of the second conveyor, and the outlet of the second conveyor is used to output demineralized bio-coke particles; the gas phase outlet of the cyclone separator is connected to the inlet of the first condensing device, the heavy oil outlet of the first condensing device is connected to the liquid phase inlet of the granulation device, the gas phase outlet of the first condensing device is connected to the inlet of the second condensing device, the light oil outlet of the second condensing device is connected to the liquid phase inlet of the pickling device, and the liquid phase outlet of the pickling device is used to output pickling waste liquid;

[0007] The first pyrolysis furnace, the second pyrolysis furnace and the coke oven are all provided with a flue gas inlet for inputting high-temperature flue gas.

[0008] According to the present invention, a metallurgical bio-coke preparation system based on bio-oil graded utilization also includes a gas furnace, and the flue gas inlets of the first pyrolysis furnace, the second pyrolysis furnace and the coke oven are respectively connected to the flue gas outlet of the gas furnace; the second condensing device and the gas phase outlet of the second pyrolysis furnace are respectively connected to the primary gas inlet of the gas furnace to input primary gas; the gas phase outlet of the coke oven is connected to the secondary gas inlet of the gas furnace pair to input secondary gas.

[0009] The present invention also provides a method for preparing metallurgical bio-coke based on bio-oil graded utilization, using the preparation system as described above, comprising:

[0010] S1: putting the biomass fuel into the first pyrolysis furnace for primary pyrolysis to generate a mixture of bio-coke, bio-oil steam and pyrolysis gas;

[0011] S2: The mixture enters the cyclone separator for gas-solid separation to obtain a gas mixture and biochar;

[0012] S3: The gas mixture enters the first condensation device and the second condensation device in sequence for condensation, and the heavy oil, light oil and pyrolysis gas are separated in sequence;

[0013] S4: putting the biocoke in step S2 into a pickling device, adding water and the light oil obtained in step S3 to remove the alkaline metals in the biocoke to obtain demineralized biocoke;

[0014] S5: putting the heavy oil obtained in step S3 and the demineralized bio-coke in step S4 into a granulation device to mix and generate demineralized bio-coke particles;

[0015] S6: feeding the demineralized biochar particles into the second pyrolysis furnace via the first conveyor for secondary pyrolysis to generate enhanced biochar and pyrolysis gas;

[0016] S7: feeding the enhanced biocoke into a coke oven for coking to generate demineralized biocoke particles and pyrolysis gas;

[0017] S8: The demineralized bio-coke particles are transported to various metallurgical links through the second conveyor for application.

[0018] According to a method for preparing metallurgical bio-coke based on bio-oil graded utilization provided by the present invention, in step S7, further comprising:

[0019] The pyrolysis gas separated in steps S3, S6 and S7 is introduced into the gas furnace as supplementary fuel to generate high-temperature flue gas after the reaction. The heat carried by the high-temperature flue gas is used to maintain the internal temperatures of the first pyrolysis furnace, the second pyrolysis furnace and the coke oven, so as to realize the recovery and recycling of the waste heat of the high-temperature exhaust gas.

[0020] According to a method for preparing metallurgical bio-coke based on graded utilization of bio-oil provided by the present invention, in step S3, the condensation temperature of the first condensation device is 100°C to 150°C, and the condensation temperature of the second condensation device is 0°C. The heavy oil is condensed by the oil bath in the first condensation device, and the light oil is condensed by the ice-water mixture in the second condensation device.

[0021] According to a method for preparing metallurgical bio-coke based on bio-oil graded utilization provided by the present invention, in step S5, it also includes:

[0022] Ethanol was added to the granulation device.

[0023] According to a method for preparing metallurgical biocoke based on graded utilization of bio-oil provided by the present invention, the pyrolysis temperature of the first pyrolysis furnace is 500°C to 600°C, the pyrolysis temperature of the second pyrolysis furnace is 200°C to 300°C, and the coking temperature of the coke oven is 950°C to 1050°C.

[0024] According to a method for preparing metallurgical bio-coke based on graded utilization of bio-oil provided by the present invention, the temperature of the gas furnace is 800°C to 1000°C.

[0025] According to a method for preparing metallurgical bio-coke based on bio-oil graded utilization provided by the present invention, after step S4, the method further comprises:

[0026] The pickling waste liquid output from the pickling device is converted into organic liquid fertilizer rich in potassium and sodium after fermentation and aging.

[0027] The present invention provides a metallurgical biocoke preparation system and method based on the graded utilization of bio-oil. The alkali metal content is controlled by washing with an acidic light oil aqueous solution, and the high-viscosity hydrophobic heavy oil assists the formation of demineralized bio-coke, and finally realizes the precise control of the performance of metallurgical bio-coke without the need for exogenous raw materials. The system and method utilize the weak acidity of pyrolysis light oil, and can effectively neutralize and reduce the alkali metal content in bio-coke without introducing additional chemical reagents, thereby solving the problem of difficult removal of alkali metals and high energy consumption in traditional methods; at the same time, the bonding properties of pyrolysis heavy oil are utilized to play a double role of binder and coating. As an adhesive, it can effectively regulate the porosity and fluidity of bio-coke, and as a coating, it can effectively block the intrusion of moisture and other polar substances, protect the internal structure of bio-coke from being destroyed, and also help to improve the strength, weather resistance and stability of bio-coke. The system and method realize the autonomous regulation of the characteristics of metallurgical bio-coke through graded condensation utilization, while improving the utilization rate of biomass, avoiding the additional costs and risks brought by the supply chain. BRIEF DESCRIPTION OF THE DRAWINGS

[0028] In order to more clearly illustrate the technical solutions in the present invention or the prior art, the following briefly introduces the drawings required for use in the embodiments or the description of the prior art. Obviously, the drawings described below are some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative work.

[0029] Figure 1 It is a schematic flow diagram of a metallurgical bio-coke preparation system based on bio-oil graded utilization provided by the present invention;

[0030] Reference numerals:

[0031] 1. First pyrolysis furnace; 2. Cyclone separator; 3. First condensation device; 4. Second condensation device; 5. Pickling device; 6. Granulation device; 7. First conveyor; 8. Second pyrolysis furnace; 9. Coke oven; 10. Gas furnace; 11. Second conveyor. DETAILED DESCRIPTION

[0032] In order to make the purpose, technical solution and advantages of the present invention clearer, the technical solution of the present invention will be clearly and completely described below in conjunction with the drawings of the present invention. Obviously, the described embodiments are part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0033] In the description of the embodiments of the present invention, it should be noted that, unless otherwise clearly specified and limited, "upper", "lower", "left", "right", etc. are only used to indicate relative positional relationships. When the absolute position of the described object changes, the relative positional relationship may also change accordingly. For ordinary technicians in this field, the specific meanings of the above terms in the embodiments of the present invention can be understood according to specific circumstances.

[0034] It should be noted that, unless otherwise clearly specified and limited, the term "connection" should be understood in a broad sense, for example, it can be directly connected or indirectly connected through an intermediate medium. For ordinary technicians in this field, the specific meanings of the above terms in the embodiments of the invention can be understood in specific circumstances.

[0035] like Figure 1 As shown, an embodiment of the present invention provides a metallurgical bio-coke preparation system based on bio-oil graded utilization, including a first pyrolysis furnace 1, a cyclone separator 2, a first condensing device 3, a second condensing device 4, a pickling device 5, a granulating device 6, a first conveyor 7, a second pyrolysis furnace 8, a coke oven 9, a gas furnace 10 and a second conveyor 11.

[0036] The inlet of the first pyrolysis furnace 1 is used to input biomass fuel, and the outlet of the first pyrolysis furnace 1 is connected to the inlet of the cyclone separator 2, the solid phase outlet of the cyclone separator 2 is connected to the solid phase inlet of the pickling device 5, the outlet of the pickling device 5 is connected to the inlet of the granulation device 6, the outlet of the granulation device 6 is connected to the inlet of the first conveyor 7, the outlet of the first conveyor 7 is connected to the solid phase inlet of the second pyrolysis furnace 8, the solid phase outlet of the second pyrolysis furnace 8 is connected to the solid phase inlet of the coke oven 9, and the solid phase outlet of the coke oven 9 is connected to the second conveyor 11 to output demineralized bio-coke particles.

[0037] The gas phase outlet of the cyclone separator 2 is connected to the inlet of the first condensing device 3, the liquid phase outlet of the condensing device 3 is connected to the liquid phase inlet of the granulating device 6, the gas phase outlet of the condensing device 3 is connected to the inlet of the second condensing device 4, the liquid phase outlet of the second condensing device 4 is connected to the liquid phase inlet of the pickling device 5, and the liquid phase outlet of the pickling device is used to output the pickling waste liquid.

[0038] It also includes a gas furnace 10, and the first pyrolysis furnace 1, the second pyrolysis furnace 8 and the coke oven 9 are all provided with a flue gas inlet to input high-temperature flue gas. The gas phase outlets of the second condensing device 4 and the second pyrolysis furnace 8 are respectively connected to the primary gas inlet of the gas furnace 10 to input primary gas; the gas phase outlet of the coke oven 9 is connected to the secondary gas inlet of the gas furnace 10 to input secondary gas.

[0039] When in use, the biomass raw material is first introduced into the first pyrolysis furnace 1, and the pyrolysis gas-solid mixture at the outlet of the first pyrolysis furnace 1 is introduced into the cyclone separator 2 to achieve gas-solid separation; the gas after gas-solid separation is introduced into the first condensation device 3 and the second condensation device 4 to separate heavy oil, light oil and high-temperature gas; the light oil and the solid after gas-solid separation enter the pickling device 5 to generate demineralized bio-coke; the demineralized bio-coke is formed and granulated with heavy oil in the granulation device 6 and then enters the second pyrolysis furnace 8 and the coke oven 9 in turn to generate demineralized bio-coke particles.

[0040] The first pyrolysis furnace 1 and the second pyrolysis furnace 8 may be a rotary kiln pyrolysis furnace, a fixed bed pyrolysis furnace, or a fluidized bed pyrolysis furnace, preferably a fluidized bed pyrolysis furnace.

[0041] The cyclone separator 2 is used to separate the gas and solid of the substances produced after the first pyrolysis. When the dust-laden airflow enters the cyclone separator from the air inlet pipe at a certain speed, it will change from linear motion to circular motion, and flow downward from the cylinder to the cone in a spiral shape along the wall of the device. The particles in the airflow will be thrown toward the wall of the device under the action of centrifugal force, and once the dust particles come into contact with the wall of the device, they will lose their inertia and fall along the wall and enter the ash hopper. The rotating and descending external vortex airflow continuously flows into the center of the separator during the descent process, forming a rotating upward internal vortex, and is discharged out of the device at the clean air outlet.

[0042] The first condensing device 3 and the second condensing device 4 are used to cool the gas and bio-oil vapor generated by pyrolysis of biomass fuel in stages. The first condensing device 3 is oil bath cooling, and a shell-side and tube-side heat exchanger, a plate heat exchanger or an air-cooled heat exchanger can be used as a condensing device. Its basic components include a condenser, an oil bath, a cooling pump, a temperature control system and a condensation collector. The working principle of the device is to take away the heat of the condensed material through a heat transfer medium oil bath, thereby condensing the steam into a liquid. The cooling oil in the oil bath will exchange heat with the steam, and the cooling oil is maintained within the set temperature range (100°C to 150°C) by the temperature control system. In order to achieve effective heat exchange, high-efficiency heat exchange materials such as copper or aluminum alloy are used inside the condenser to increase the condensation surface area and improve the heat exchange efficiency. The selection of cooling oil should take into account factors such as thermal stability, thermal conductivity and low viscosity. Commonly used cooling oils include mineral oil, synthetic oil or special oil, which have high high temperature resistance and can effectively reduce temperature fluctuations. In order to ensure the condensation effect, the cooling oil needs to be circulated and filtered regularly to prevent impurities from affecting the heat exchange efficiency. A temperature control system may be provided inside the oil bath to monitor the temperature of the cooling oil in real time through a temperature sensor to ensure that the temperature is constant during the condensation process and achieve a sufficient condensation effect. The cooling material of the first condensation device 3 is heavy oil.

[0043] The second condensing device 4 is cooled by an ice-water mixture. A shell-side and tube-side heat exchanger, a double-tube heat exchanger or a cooling tower can be used as a condensing device. The basic components of the device include a condensing tube, an ice-water mixing tank, a cooling pump, a condensing water circulation system and a temperature control system. The condensation principle is to use an ice-water mixture as a cooling medium to absorb the heat released by steam, thereby condensing the steam into a liquid. The use of an ice-water mixture can provide a strong cooling capacity at a lower temperature, which helps to improve the condensation efficiency. Specifically, an ice-water mixture circulates in the cooling pipe of the condenser, contacts with the steam through an efficient heat exchange system, and quickly reduces the steam temperature. During the condensation process, the cooling water temperature is controlled at 0°C. The automatic adjustment system can adjust the water flow and cooling capacity according to the actual temperature change of the steam to ensure the stability and adequacy of the condensation process. The flow of cooling water is maintained by a cooling pump, and the circulating water system needs to be equipped with a filtering device to remove impurities in the water, prevent scaling, and ensure condensation efficiency. The cooling material of the second condensing device 4 is a mixture of light oil and water, and the condensed gas is passed into the gas furnace 10 as a supplementary fuel. There are significant differences in composition and properties between heavy oil and light oil. Heavy oil contains more macromolecular compounds, such as levoglucosan, trans-isoeugenol and 1,2-cyclopentanedione, has a higher specific gravity and viscosity, poor volatility, and is suitable as an adhesive; light oil is composed of smaller molecular compounds, such as acetone, methanol and acetic acid, has a lower specific gravity and viscosity, high volatility and is suitable as an eluent.

[0044] The pickling device 5 can adopt a single-plate solid-phase pickling device. When working, light oil and water are mixed and enter from the pipeline to elute the biocoke particles. The pickling device 5 is divided into two parts, including a box cover and a box body. The upper part of the box cover is connected to the motor, and the lower part is connected to the stirrer. During pickling, the stirrer can be connected to the power supply to start the stirrer, and the contents are mixed evenly by stirring to achieve the pickling effect; the box body is used to hold the materials that need to be stirred and pickled, and there is a connecting pipe outside for water injection.

[0045] The granulating device 6 can use a disc granulator or a twin-screw extruder granulator as a granulating device, and its basic components include a feeding system, a granulating cylinder, a rotating device, a screening device, a cooling system, a discharging system, etc. Its main function is to form particles of a certain size and shape through the mechanical force of the material. The feeding system evenly feeds the material into the granulator through a vibrating feeder to ensure the stability of the material flow. A roller is provided in the granulating cylinder, which generates shear force through rotation, so that the material forms particles under appropriate pressure and humidity conditions. The particle size and shape can be adjusted according to demand, and the pressure ranges from 100MPa to 200MPa, and the humidity ranges from 30% to 50%. In order to ensure the stability of the particles, heavy oil is added as an adhesive in an appropriate amount, and the addition amount of heavy oil ranges from 10% to 30%. The screening device is used to classify the particles according to the particle size, ensure the uniformity of the particles, and remove particles that are too large or too small. The cooling system uses air flow cooling, spray cooling or water cooling system to ensure that the particles will not stick or deform due to excessive temperature after forming, thereby maintaining the strength and stability of the particles. The discharging system transports the formed particles to the collection area through an automatic discharging device.

[0046] The first conveyor 7 and the second conveyor 11 can be belt conveyors, which are mainly composed of a conveyor belt, a driving device, a roller, a tensioning device, a supporting structure, a feeding and discharging system, a control system, etc., and can efficiently and stably realize horizontal or inclined transportation of materials. The conveyor belt part is made of wear-resistant rubber or polyester material to ensure durability and stability in long-term operation; the driving device includes an electric motor and a reducer, which can adjust the conveying rate through variable frequency speed regulation technology to meet different transportation needs. The control system adopts PLC automatic control, which can monitor the operating status of the equipment in real time, adjust parameters such as speed, start and stop, and ensure continuity and efficiency during transportation.

[0047] The coke oven 9 can adopt a side-loading coal coke oven, which is mainly composed of a furnace body, a heating system, a coal feeding system, a gas exhaust system, a coke discharging system and a control system. The side-loading coal coke oven feeds the bio-coke into the furnace body through the side feeding port to ensure that the bio-coke is evenly distributed, optimize the dry distillation reaction, and improve the yield and quality of coke. The furnace body is built with refractory bricks and high-temperature refractory materials, and can withstand an operating temperature of up to 1100°C. The heating system adopts a gas heating system to heat the bio-coke through the combustion zone in the furnace body to promote the pyrolysis reaction of the bio-coke and generate bio-coke. The bio-coke enters the furnace evenly through a vibrating feeder. Compared with the traditional top-loading coke oven, the side loading method can effectively avoid uneven distribution of coal and improve reaction efficiency. The gas exhaust system recovers and treats waste gas through a gas furnace, which meets environmental emission standards. The coke discharging system takes the coke out of the furnace through an automatic coke unloading device. The control system manages the coke oven's temperature, gas flow, feeding amount and other parameters through a PLC automatic control system to ensure stable and efficient operation of the coke oven.

[0048] The main function of the gas furnace 10 is to supply heat for each process of steel production. Since the temperature of the gas after condensation cannot meet the use conditions, by passing the gas into the subsequent gas furnace 10, it can not only provide supplementary fuel for the ironmaking process, but also use the high-temperature exhaust gas after combustion to introduce the pyrolysis furnace and coke oven for waste heat utilization. The gas furnace 10 can adopt a regenerative gas heating furnace, which has key components such as advanced gas combustion technology, temperature control system, and exhaust gas recovery system. The furnace body is usually made of high-temperature resistant materials or refractory bricks and can operate stably at a temperature of up to 1000°C. The combustion system adopts low-nitrogen combustion technology, which effectively reduces the emission of pollutants such as nitrogen oxides while ensuring combustion efficiency. The temperature control system in the furnace is composed of a PLC automatic control system, which monitors the temperature in the furnace in real time and makes precise adjustments to ensure the uniformity and stability of the heat source supply. The exhaust gas recovery system reduces the emission of harmful substances through efficient dust removal, desulfurization and denitrification devices, while recovering and utilizing the waste heat in the exhaust gas to provide a supplementary heat source for the pyrolysis furnace and coke oven, thereby improving the overall energy utilization efficiency. The cooling system uses water cooling or air cooling technology to ensure safe operation of the equipment and avoid equipment damage caused by overtemperature.

[0049] The embodiment of the present invention further provides a method for preparing metallurgical bio-coke based on bio-oil graded utilization, using the preparation system as described above, comprising:

[0050] S1: putting biomass fuel into the first pyrolysis furnace 1 for pyrolysis to generate a mixture of biochar, bio-oil vapor and pyrolysis gas; the pyrolysis temperature of the first pyrolysis furnace 1 is 500° C. to 600° C. In some specific embodiments, the first pyrolysis furnace 1 performs pyrolysis for 30 minutes at 550° C., 1 atmosphere pressure and inert atmosphere to generate biochar particles, gas and oil vapor.

[0051] S2: The mixture enters cyclone separator 2 for gas-solid separation to obtain a gas mixture and biochar.

[0052] S3: The gas mixture enters the first condensing device 3 and the second condensing device 4 for condensation to precipitate heavy oil, light oil and pyrolysis gas; the condensation temperature of the first condensing device 3 is 100°C to 150°C, and the condensation temperature of the second condensing device 4 is 0°C. The liquid phase condensed by the first condensing device 3 is heavy oil, and the liquid phase condensed by the second condensing device 4 is a mixture of light oil and water.

[0053] S4: The biocoke in step S2 is put into the pickling device 5, and water and the light oil obtained in step S3 are added to remove the alkaline metals in the biocoke to obtain demineralized biocoke. In some embodiments, the ratio of water, biocoke and light oil is generally between 2-5:0.8-1.2:0.3-1. Preferably, the ratio of water, biocoke and light oil is 3:1:0.5.

[0054] S5: The heavy oil in step S3 and the demineralized bio-coke in step S4 are put into a granulation device 6, and ethanol is put into the granulation device 6 to dilute the bio-heavy oil with strong viscosity, and mix to produce bio-coke particles. In some embodiments, the mass ratio of demineralized bio-coke: heavy oil: ethanol is 3-5: 0.5-1.5: 0.5-1.5. Preferably, the ratio of demineralized bio-coke: heavy oil: ethanol is 4: 1: 1.

[0055] S6: The biochar particles are fed into the second pyrolysis furnace 8 via the first conveyor 7 for secondary pyrolysis to generate enhanced biochar and pyrolysis gas; the pyrolysis temperature of the second pyrolysis furnace 8 is 200°C to 300°C, and the pyrolysis is carried out for 30 minutes under 1 atmosphere of pressure and inert atmosphere. Compared with the original biochar, the enhanced biochar has higher compressive strength and lower reactivity in the high temperature section. In addition, during the coking process, the enhanced biochar has a uniform structure and a relatively slow gas release, which reduces the impact and corrosion on the coking furnace.

[0056] S7: Put the enhanced biocoke into the coke oven 9 for coking to generate demineralized biocoke particles and pyrolysis gas. In some embodiments, the coke oven 9 performs coking for 120 minutes at 950°C to 1050°C, 1 atmosphere pressure and inert atmosphere to remove volatiles and increase strength. Compared with the enhanced biocoke, the biocoke after coking is more in line with the metallurgical coke standards in terms of compressive strength, reactivity, CRI (coke reactivity index) and CSR (coke strength after reaction), and the proportion of biomass replacing coal coke in the metallurgical field is expected to increase further.

[0057] S8: The pyrolysis gas separated in steps S3, S6 and S7 is used as supplementary fuel to be introduced into the gas furnace 10. After the reaction, high-temperature exhaust gas is generated. The heat carried by the high-temperature exhaust gas is used to maintain the internal temperature of the pyrolysis furnaces 1 and 8 and the coke oven 9, so as to achieve the purpose of efficient recovery and recycling of the waste heat of the high-temperature exhaust gas. Among them, the primary fuel gas is generated by the pyrolysis furnace, which has a lower temperature and is mainly composed of volatile organic compound gases with a lower calorific value. Due to its complex composition, the light organic compounds in the fuel gas need to be further purified and treated before they can be effectively used. In contrast, the secondary fuel gas is mainly composed of combustible gases such as carbon monoxide, methane, and hydrogen, with a higher calorific value, and can be put into the gas furnace without excessive treatment.

[0058] S9: The demineralized bio-coke particles are transported to various metallurgical links through the second conveyor 11 for application.

[0059] In addition, it should be added that the pickling waste liquid output from the liquid phase outlet of the pickling device 5 in step S4 is separated and dechlorinated and desulfurized by standing or accelerating sedimentation to remove the solid particles and suspended matter in the waste liquid, and remove the suspended matter and some harmful impurities therein. Next, the waste liquid enters the fermentation tank for microbial fermentation. During the fermentation process, anaerobic microorganisms begin to decompose the organic components in the waste liquid under suitable temperature, humidity and oxygen conditions. The metabolism of microorganisms can not only decompose the complex organic matter in the waste liquid, convert it into nutrients such as organic acids, amino acids, phenolic compounds, but also promote the conversion of inorganic salts in the waste liquid, and convert minerals such as sodium and potassium into a form that can be absorbed by plants. After the fermentation is completed, the waste liquid enters the aging tank for natural aging for several weeks to several months. The aging process can make the organic matter produced in the fermentation process more stable, and promote the nutrients in the liquid to form a balanced release pattern. In the aged liquid fertilizer, the concentrations of major nutrients such as potassium, sodium, and nitrogen are increased, and the release of these nutrients is continuous and stable, which can meet the growth needs of different crops. In addition, the aging process can further remove some possible harmful components to ensure the safety of liquid fertilizer. Finally, the fermented and aged waste liquid is converted into nutrient-rich organic liquid fertilizer, which not only contains a large amount of potassium, sodium, nitrogen, phosphorus, calcium and other major nutrients required by plants, but also contains beneficial microorganisms, which can improve the biological activity of the soil and promote the improvement of soil structure.

[0060] The following describes the process in conjunction with some specific embodiments.

[0061] Example 1

[0062] The biomass is kept at 550° C. for 30 minutes in the first pyrolysis furnace 1 and enters the cyclone separator 2 for gas-solid separation. The solid bio-coke enters the acid washing equipment 5 for acid washing with light oil to obtain bio-coke.

[0063] Comparative Example 1

[0064] The biomass is kept at 550° C. for 30 min in the first pyrolysis furnace 1 and enters the cyclone separator 2 for gas-solid separation to obtain biochar.

[0065] Comparative Example 2

[0066] The biomass is kept at 550° C. for 30 minutes in the first pyrolysis furnace 1 and enters the cyclone separator 2 for gas-solid separation. The solid biochar enters the acid washing equipment 5 for acid washing with 1 mol / L hydrochloric acid to obtain biochar.

[0067] The alkaline metal and alkaline earth metal (AAEM) contents of biochar of Comparative Examples 1, 2 and Example 1 are shown in Table 1. It can be seen from Table 1 that light oil is effective as an eluent in the removal of biochar AAEM. And compared with hydrochloric acid, light oil has a stronger de-elution rate, which may be due to the presence of phenols in light oil, which enhances the leaching of organic complex metals. In addition, light oil and biochar have hydrophobic interactions, which expands the reaction surface of alkaline and alkaline earth metals in contact with water and organic acids.

[0068] Table 1 Alkaline metal and alkaline earth metal (AAEM) content and desalting rate in samples

[0069]

[0070] Example 2

[0071] The biomass is kept at 550°C for 30 minutes in the first pyrolysis furnace 1, and enters the cyclone separator 2 for gas-solid separation. The solid biochar enters the acid washing equipment 5 for acid washing with light oil, and then enters the granulation equipment 6 for molding and granulation. It is sent to the second pyrolysis furnace 8 via the first conveyor 7 and kept at 250°C for 30 minutes, and enters the coking furnace 9 and kept at 1000°C for 120 minutes for coking to obtain biocoke particles.

[0072] Comparative Example 3

[0073] The biomass is kept at 550° C. for 30 minutes in the first pyrolysis furnace 1 and enters the cyclone separator 2 for gas-solid separation. The solid biochar is sent to the coking furnace 9 and kept at 1000° C. for 120 minutes for coking to obtain biochar particles.

[0074] Comparative Example 4

[0075] The bituminous coal is sent to a coking furnace 9 and maintained at 1000° C. for 120 minutes for coking to obtain metallurgical coke particles.

[0076] The compressive strength, ignition temperature, burnout temperature, CRI (coke reactivity index) and CSR (coke strength after reaction) of Comparative Examples 3, 4 and Example 2, these key parameters for evaluating metallurgical coke are shown in Table 2. As can be seen from Table 2, the biocoke prepared by this method (Example 2) is significantly better than the traditional biocoke (Comparative Example 3) in all data, and the gap with coal coke (Comparative Example 4) is relatively small. And Example 2 is very close to the secondary metallurgical coke in terms of the two key indicators of metallurgical coke specified in the national standards of CRI and CSR. These data all show that the biocoke prepared by this system and method has great potential in promoting the application of biomass to replace coal coke in the metallurgical field.

[0077] Table 2 Key parameters of metallurgical coke

[0078]

[0079] *According to the national standard of metallurgical coke GB / T 1996-2017

[0080] This embodiment provides a metallurgical biocoke preparation system and method based on bio-oil graded utilization, which controls the alkali content by washing with acidic light oil aqueous solution, and assists the formation of demineralized bio-coke with high viscosity hydrophobic heavy oil, and finally realizes the precise control of metallurgical bio-coke performance without exogenous raw material demand. The system and method utilize the weak acidity of pyrolysis light oil, and can effectively neutralize and reduce the alkali metal content in bio-coke without introducing additional chemical reagents, thereby solving the problem of difficult removal of alkali metals and high energy consumption in traditional methods; at the same time, the bonding properties of pyrolysis heavy oil are utilized to play a double role of binder and coating. As an adhesive, it can effectively regulate the porosity and fluidity of bio-coke, and as a coating, it can effectively block the intrusion of moisture and other polar substances, protect the internal structure of bio-coke from being destroyed, and also help to improve the strength, weather resistance and stability of bio-coke. Through graded utilization, the system and method realizes the autonomous regulation of the characteristics of metallurgical bio-coke, while improving the utilization rate of biomass, avoiding the additional costs and risks brought by the supply chain.

[0081] It can be seen from the above examples that the system and method for preparing metallurgical biocoke provided by the present invention have the following advantages:

[0082] First, based on the properties of biomass oil, a new biomass oil processing method is proposed. The disadvantages of bio-oil being unstable and easy to separate are utilized to effectively utilize the bio-oil, a by-product of coking, and improve the added value of biomass pyrolysis multi-product products.

[0083] Second, the weak acidity of pyrolysis light oil is used to effectively reduce the alkali metal content in bio-coke, avoiding the high energy consumption of traditional water-washing and acid-washing biomass drying and the difficulty in removing organic alkali metals in bio-coke. This achieves the efficient synthesis of demineralized biomass coke, obtains high-quality bio-coke, and realizes the goal of producing high-quality products from biomass, which plays an important role in promoting the utilization of biomass energy.

[0084] Third, high-viscosity hydrophobic heavy oil can play a dual role as a binder and a coating, achieving coordinated regulation of the strength and combustion rate of biochar without the need for exogenous binders.

[0085] Fourth, the present invention proposes a new metallurgical biocoke performance control technology route, which effectively reduces the high reactivity of biocoke and increases the addition ratio of biocoke in metallurgical coke.

[0086] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, rather than to limit it. Although the present invention has been described in detail with reference to the aforementioned embodiments, those skilled in the art should understand that they can still modify the technical solutions described in the aforementioned embodiments, or make equivalent replacements for some of the technical features therein. However, these modifications or replacements do not deviate the essence of the corresponding technical solutions from the spirit and scope of the technical solutions of the embodiments of the present invention.

Claims

1. A metallurgical bio-coke preparation system based on bio-oil graded utilization, characterized in that: It includes a first pyrolysis furnace, a cyclone separator, a first condensation device, a second condensation device, a pickling device, a granulation device, a first conveyor, a second pyrolysis furnace, a coke oven, and a second conveyor; The inlet of the first pyrolysis furnace is used to input biomass fuel, the outlet of the first pyrolysis furnace is connected to the inlet of the cyclone separator, the solid phase outlet of the cyclone separator is connected to the solid phase inlet of the pickling device, the solid phase outlet of the pickling device is connected to the solid phase inlet of the granulation device, the outlet of the granulation device is connected to the inlet of the first conveyor, the outlet of the first conveyor is connected to the solid phase inlet of the second pyrolysis furnace, the solid phase outlet of the second pyrolysis furnace is connected to the solid phase inlet of the coke oven, the solid phase outlet of the coke oven is connected to the inlet of the second conveyor, and the outlet of the second conveyor is used to output demineralized bio-coke particles; the gas phase outlet of the cyclone separator is connected to the inlet of the first condensing device, the heavy oil outlet of the first condensing device is connected to the liquid phase inlet of the granulation device, the gas phase outlet of the first condensing device is connected to the inlet of the second condensing device, the light oil outlet of the second condensing device is connected to the liquid phase inlet of the pickling device, and the liquid phase outlet of the pickling device is used to output pickling waste liquid; The first pyrolysis furnace, the second pyrolysis furnace and the coke oven are all provided with a flue gas inlet for inputting high-temperature flue gas.

2. The metallurgical bio-coke preparation system based on bio-oil graded utilization according to claim 1, characterized in that: Also includes a gas stove; The flue gas inlets of the first pyrolysis furnace, the second pyrolysis furnace and the coke oven are respectively connected to the flue gas outlet of the gas furnace; the gas phase outlet of the second condensing device and the second pyrolysis furnace are respectively connected to the primary gas inlet of the gas furnace to input primary gas; the gas phase outlet of the coke oven is connected to the secondary gas inlet of the gas furnace pair to input secondary gas.

3. A method for preparing metallurgical bio-coke based on graded utilization of bio-oil, characterized in that: A preparation system according to any one of claims 1 and 2, comprising: S1: putting the biomass fuel into the first pyrolysis furnace for primary pyrolysis to generate a mixture of bio-coke, bio-oil steam and pyrolysis gas; S2: The mixture enters the cyclone separator for gas-solid separation to obtain a gas mixture and biochar; S3: The gas mixture enters the first condensation device and the second condensation device in sequence for condensation, and the heavy oil, light oil and pyrolysis gas are separated in sequence; S4: putting the biocoke in step S2 into a pickling device, adding water and the light oil obtained in step S3 to remove the alkaline metals in the biocoke to obtain demineralized biocoke; S5: putting the heavy oil obtained in step S3 and the demineralized bio-coke in step S4 into a granulation device to mix and generate demineralized bio-coke particles; S6: feeding the demineralized biochar particles into the second pyrolysis furnace via the first conveyor for secondary pyrolysis to generate enhanced biochar and pyrolysis gas; S7: feeding the enhanced biocoke into a coke oven for coking to generate demineralized biocoke particles and pyrolysis gas; S8: The demineralized bio-coke particles are transported to various metallurgical links through the second conveyor for application.

4. The method for preparing metallurgical bio-coke based on bio-oil graded utilization according to claim 3, characterized in that: Further including: The pyrolysis gas separated in steps S3, S6 and S7 is introduced into the gas furnace as supplementary fuel to generate high-temperature flue gas after the reaction. The heat carried by the high-temperature flue gas is used to maintain the internal temperatures of the first pyrolysis furnace, the second pyrolysis furnace and the coke oven, so as to realize the recovery and recycling of the waste heat of the high-temperature exhaust gas.

5. The method for preparing metallurgical bio-coke based on bio-oil graded utilization according to claim 3, characterized in that: In step S3, the condensation temperature of the first condensation device is 100°C to 150°C, and the condensation temperature of the second condensation device is 0°C. The heavy oil is condensed by the oil bath in the first condensation device, and the light oil is condensed by the ice-water mixture in the second condensation device.

6. The method for preparing metallurgical bio-coke based on bio-oil graded utilization according to claim 3, characterized in that: In step S5, it also includes: Ethanol was added to the granulation device.

7. The method for preparing metallurgical bio-coke based on bio-oil graded utilization according to claim 3, characterized in that: The pyrolysis temperature of the first pyrolysis furnace is 500°C to 600°C, the pyrolysis temperature of the second pyrolysis furnace is 200°C to 300°C, and the coking temperature of the coke oven is 950°C to 1050°C.

8. The method for preparing metallurgical bio-coke based on bio-oil graded utilization according to claim 4, characterized in that: The temperature of the gas furnace is 800°C to 900°C.

9. The method for preparing metallurgical bio-coke based on bio-oil graded utilization according to any one of claims 3 to 8, characterized in that: After step S4, the method further includes: The pickling waste liquid output from the pickling device is converted into organic liquid fertilizer rich in potassium and sodium after fermentation and aging.

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