A multi-stage auger-type continuous modified biochar production device coupled with raw material blasting and mineral loading and its application

Abstract

The present invention belongs to the technical field of renewable resources, and discloses a multi-stage auger-type continuous modified biochar production equipment that couples raw material blasting and mineral loading, and its application. The equipment includes an equipment housing 1, a special-shaped auger 2, a drying and preheating zone 3, a main reaction zone 4, a modification zone 5 and a stabilization zone 6 arranged in sequence along the axial direction of the equipment housing 1. Through the segmented design, the influence of bio-oil and pyrolysis gas on the yield and quality of modified biochar is avoided. In addition, the present invention sets up a feed port at the front end of the modification zone, and various types of modifiers can be added to achieve continuous production of modified biochar with high adsorption performance. The present invention also uses steam explosion as a pretreatment for biomass carbonization, which can effectively improve the pyrolysis characteristics of biomass, increase the specific surface area and micropore volume of biochar, and improve the adsorption performance of biochar.

Description

Technical Field

[0001] The present invention belongs to the technical field of renewable resources, and in particular relates to a multi-stage auger-type continuous modified biochar production device coupled with raw material blasting and mineral loading, and an application thereof. Background Art

[0002] Biochar is a solid product generated by high temperature (<700℃) thermal cracking of biomass materials in anoxic or anaerobic environment. It is an adsorbent with a wide source and is economical and easy to obtain. Biomass pyrolysis carbonization is a complex thermochemical reaction process. The preparation of biochar by this technology will be accompanied by byproducts such as bio-oil and pyrolysis gas. The main factors affecting the carbonization process include pyrolysis temperature, heating rate and temperature control time, carrier gas type, material properties, etc. The reaction process mainly includes three stages: the first stage is the drying stage, which is below 200℃, mainly due to the evaporation of free, adsorbed and crystalline water by heat, causing macroscopic water loss in biomass, and initial condensation of macromolecules such as cellulose and lignin; the second stage is the volatile analysis stage, which is mainly due to the thermal decomposition reaction of cellulose, hemicellulose and lignin in the biomass to release volatiles of bio-oil and pyrolysis gas; the third stage is the carbonization stage, which is mainly the formation of a mixed product of graphite and amorphous carbon from the semi-coke after pyrolysis.

[0003] At present, the production of biochar from agricultural and forestry wastes is an important issue to solve the source of biochar raw materials and expand the utilization of renewable resources. The biochar obtained by carbonizing agricultural and forestry wastes has excellent physical and chemical properties such as rich microporous structure, large specific surface area, good adsorption effect, and strong stability. It has broad application prospects in soil improvement, pollution control, carbon fixation and emission reduction, and energy electrodes. However, the original biochar still has problems such as limited adsorption capacity and weak adsorption selectivity during the adsorption of pollutants. Improving its adsorption capacity and adsorption selectivity by optimizing the structure and properties of biochar and the chemical composition of its surface is the key to achieving efficient application of biochar.

[0004] However, the preparation of modified biochar is currently limited to laboratory heat pipe type, muffle furnace and fixed bed pyrolysis equipment, all of which belong to intermittent biochar carbonization equipment, and have problems such as high energy consumption, long carbonization time, inability to produce continuously, low efficiency, and difficulty in industrial promotion. Chinese invention patent CN110252242A discloses a preparation method of modified biochar and modified biochar, wherein the biochar is mixed with iron salt colloid and calcined under nitrogen protection conditions in a tubular furnace to obtain modified biochar. Specifically, the biochar can only be discharged from the entire furnace at one time, resulting in repeated heating and cooling of the carbonization furnace, wasting energy; and it requires a long time to heat up and cool down, and the production efficiency is low. At present, there are mainly two types of continuous biomass pyrolysis carbonization equipment in industrial production, namely gravity vertical flow continuous pyrolysis carbonization device and spiral continuous pyrolysis carbonization equipment. Chinese invention patent CN103614151A discloses a horizontal continuous biochar carbonization equipment, which can achieve continuous production of biochar by spiral conveying. However, the continuous pyrolysis carbonization device mainly relies on temperature control to produce different types of native biochar. The product function is single and it is unable to realize the production of modified biochar.

[0005] Therefore, it is necessary to establish a pyrolysis device that can be continuously produced and suitable for the preparation of modified biochar and its application method. Summary of the invention

[0006] In view of this, the first object of the present invention is to provide a multi-stage auger-type continuous modified biochar production equipment that couples raw material blasting and mineral loading to address the shortcomings of modified biochar preparation equipment in the prior art.

[0007] In order to achieve the above object, the present invention adopts the following technical solution:

[0008] A multi-stage augers type continuous modified biochar production equipment that couples raw material blasting and mineral loading is a multi-stage continuous pyrolysis equipment, comprising an equipment shell 1, a special-shaped augers 2, a drying and preheating zone 3, a main reaction zone 4, a modification zone 5 and a stabilization zone 6 arranged in sequence along the axial direction of the equipment shell 1, wherein the drying and preheating zone 3, the main reaction zone 4, the modification zone 5 and the stabilization zone 6 are respectively separated by temperature-resistant baffles 7, the special-shaped augers 2 continuously extend along the axial direction of the equipment shell 1 and sequentially pass through the drying and preheating zone 3, the main reaction zone 4, the modification zone 5 and the stabilization zone 6 arranged in the reaction shell 1, the feeding end of the drying and preheating zone 3 is provided with a feeding port 8, the feeding end of the modification zone 5 is provided with a modifier feeding port 9, and the discharging end of the stabilization zone 6 is provided with a discharging port 23.

[0009] When the modified biochar technology is combined with the continuous production technology, the second stage of the biochar cracking process is accompanied by the production of byproducts such as bio-oil. However, bio-oil has high viscosity and is easy to block the reaction device in the narrow channel of the continuous carbonization furnace, which will also cause the biochar to be unable to fully contact with the modifier, hindering the modified product rate.

[0010] The present invention adopts a segmented continuous pyrolysis furnace, and separates the main reaction zone 4 and the modification zone 5 by a temperature-resisting baffle 7. The bio-oil and pyrolysis gas generated during the biochar pyrolysis reaction can be discharged by setting a pyrolysis gas discharge port 15 in the main reaction zone 4, so as to facilitate the full mixing of the biochar after the primary carbonization treatment with the modifier in the subsequent modification zone 5, thereby avoiding the influence of the bio-oil and pyrolysis gas on the yield and quality of the modified biochar. At the same time, the present invention also sets a modifier feed port 9 at the feed end of the modification zone 5 for adding different types of modifiers to achieve the modified preparation of biochar.

[0011] Preferably, the device further comprises temperature control components 10 independently arranged in the drying and preheating zone 3, the main reaction zone 4, the modification zone 5 and the stabilization zone 6 respectively.

[0012] The temperature control assembly 10 is used to adjust the temperature of each reaction zone separately in the working state.

[0013] Preferably, the discharge end of the drying and preheating zone 3 is provided with a water vapor discharge port 11, and the water vapor discharge port 11 is provided with a gas check valve 12; the discharge end of the main reaction zone 4 is provided with a cracking gas discharge port 15, and the cracking gas discharge port 15 is provided with a gas check valve 16; the discharge end of the stabilization zone 6 is provided with a residual gas discharge port 17, and the residual gas discharge port 17 is provided with a gas check valve 18. Further preferably, the feed end of the drying and preheating zone 3 is connected to a steam explosion pretreatment system 14 through a conveyor belt 13.

[0014] The steam explosion pretreatment system uses a closed device to heat the steam to reach the target pressure. After maintaining the pressure for a certain period of time, the steam ejection principle is used to complete the instantaneous ejection steam explosion machine to explode the biomass raw materials. Since the explosion is completed in milliseconds, the water vapor undergoes adiabatic expansion and works, converting the steam internal energy into mechanical energy and acting on the biomass tissue cell layers, which increases the explosion energy density and fully decomposes the material, shortening the steam pressure holding time from more than ten minutes to tens of seconds, and no chemical addition is required, which not only saves steam energy consumption, but also improves the production capacity of the equipment.

[0015] Preferably, the drying preheating zone 3 adopts a U-shaped augers 19, the spiral outer diameter of the U-shaped augers 19 is 30.0≤D≤80.0mm, the spiral shaft diameter is 15.2-60.0mm, the pitch S is 30.0-100.0mm, and the length of the drying zone is 500-1000mm; the main reaction zone 4 adopts a U-shaped augers 20, the spiral outer diameter of the U-shaped augers 20 is 45.0≤D≤120.0mm, the spiral shaft diameter is 15.2-60.0mm, the pitch S is 30.0-150.0mm, and the length of the main reaction zone is 800-150 0mm; the modified zone 5 adopts a cylindrical agitator 21, the spiral outer diameter of the cylindrical agitator 21 is 45.0≤D≤120.0mm, the spiral shaft diameter is 15.2-60.0mm, the pitch S is 30.0-150.0mm, and the length of the modified zone is 500-1000mm; the stabilization zone 6 adopts a circular agitator 22, the spiral outer diameter of the circular agitator 22 is 30.0≤D≤80.0mm, the spiral shaft diameter is 15.2-60.0mm, the pitch S is 30.0-100.0mm, and the length of the stabilization zone is 500-1000mm.

[0016] The second object of the present invention is to provide an application of the above-mentioned continuous multi-stage auger-type modified biochar complete set of equipment, comprising the following steps:

[0017] Step 1, start the equipment, set the auger speed, and set the temperatures of the drying and preheating zone 3, the main reaction zone 4, the modification zone 5 and the stabilization zone 6 respectively;

[0018] Step 2: At the start of the reaction, the reaction raw materials are fed into the feed port 8, the gas one-way valve 12 of the water vapor discharge port 11, the gas one-way valve 16 of the cracked gas discharge port 15 and the gas one-way valve 18 of the residual gas discharge port 17 are opened, and the water vapor generated by heating is used to discharge the oxygen in the multi-stage agitator, thereby providing an oxygen-free or oxygen-deficient state for the subsequent pyrolysis and carbonization reaction of the materials;

[0019] Step 3, adding a modifier through the modifier feed port 9;

[0020] Step 4: Collect the modified biochar material from the outlet of the stabilization zone.

[0021] It is worth noting that the feeding mode of the feed inlet 8 and the modifier feed inlet 9 is closed feeding to prevent the entry of air, especially oxygen.

[0022] Considering that oxygen has an important influence on the preparation of biochar materials, in some implementation schemes, the oxygen in the multi-stage agitator can be discharged through the water vapor generated by equipment heating, providing an anaerobic or anoxic environment for subsequent material pyrolysis and carbonization reactions.

[0023] Preferably, the rotation speed of the special-shaped agitator 2 is 1-100r / min, the temperature of the drying and preheating zone 3 is controlled at 105-150°C, the temperature of the main reaction zone 4 is controlled at 300-600°C, the temperature of the modification zone 5 is controlled at 300-600°C, and the temperature of the stabilization zone 6 is controlled at 0-50°C.

[0024] Preferably, the reaction raw materials include one or more of wheat straw, corn straw, bamboo chips, tomato straw, cotton straw, rice straw, rape straw, coconut shells, peanut shells, shells, and eggshells, and the modifier includes one or more of bentonite, montmorillonite, kaolin, calcium carbonate, calcium dihydrogen phosphate, nano-SiO2, magnesium oxide, ferroferric oxide, ferric oxide, and Co-Fe2O4.

[0025] Preferably, the step further comprises steam explosion pretreatment, and the raw materials after steam explosion pretreatment are sent to the drying and preheating zone 3.

[0026] Further preferably, the reaction pressure of the steam explosion is 1.0-2.0 MPa, and the pressure holding time is 60-600 s.

[0027] It is worth noting that the size of the filling coefficient of the material in the reaction tube will cause irregular and complex movement of the material during the movement, affecting the uniformity and filling stability of the material spiral conveying, thereby seriously affecting the energy loss of the material spiral conveying. The raw materials after blasting are easy to crush, the filling coefficient is smaller than that of the unblasted raw materials, the material stacking height is low, and most of the materials are close to the outside of the spiral, with a smaller circumferential speed and a larger axial speed. The movement of the material in the conveying direction is much more obvious than the circumferential direction, and the moving slip surface is almost parallel to the conveying direction. The vertical additional material flow in the conveying direction is significantly weakened, and the energy loss is greatly reduced. Steam explosion can break the dispersion of biomass and has a good effect. It can significantly increase the specific surface area of ​​biochar, increase micropores and functional groups such as hydroxycarbonyl, and improve adsorption performance. In addition, the steam explosion process does not require the addition of any chemical reagents, and the production process has excellent environmental protection characteristics.

[0028] Therefore, the present invention first uses the steam explosion pretreatment system 14 to perform steam explosion pretreatment on the reaction raw materials, and then sends the crushed biomass into the drying / preheating zone 3, heats it to 105-150°C, evaporates the water and overflows, and performs drying, which is beneficial to the high-temperature cracking of the main reaction zone 4 in the next step. In order to ensure rapid, continuous and uniform feeding of this area, the auger in this area adopts a U-shaped auger, and the auger angle is set to a small angle, the outer diameter of the auger is small, the distance between the auger and the auger is small, the density is high, and the material is transported quickly under the same speed conditions. At the same time, the good sealing of the system is ensured, which provides an oxygen-free or oxygen-deficient state for the subsequent pyrolysis and carbonization reaction of the material.

[0029] Then, the reactants enter the main reaction zone 4, and the temperature is controlled at 300-600°C for carbonization and pyrolysis. This process mainly involves the pyrolysis of cellulose, hemicellulose and lignin, which produces a large amount of combustible gas. The fiber glycosides in the cellulose are decomposed and carbonized to form left-handed glucose, and the CC and CO bonds in the left-handed glucose are broken and decomposed to release H2, CO and tar. The main reaction zone 4 has a long reaction zone length, which is conducive to uniform and sufficient cracking. A cracking gas outlet 14 is set at the end of this area to facilitate the removal of a large amount of pyrolysis gas in this process. The U-shaped augers are set at a small angle, the augers are small, and the outer diameter of the augers is small. Under the same rotation speed conditions, the material is transported quickly.

[0030] Furthermore, in order to ensure sufficient mixing of the biochar and the modifier in the modification zone 5, the present invention adopts a cylindrical agitator, sets the agitator angle to a large angle, has a large outer diameter, a wide distance between agitators, and a low packing density. The spiral feeding process will destroy the existing compaction layer, reduce the obstacles to heat and mass transfer between material layers, material particles and between each other, facilitate full reaction, and improve yield and energy acquisition rate.

[0031] Finally, the present invention arranges the stabilization zone 6 at the discharge end of the modification zone 5. At this time, the modified biochar is at a relatively high temperature and needs to be properly cooled to reduce the temperature to avoid direct contact with air and spontaneous combustion. Considering that this process should be kept sealed to reduce the air from entering the pyrolysis system, affecting the quality of the biochar and the safety of the system operation, the present invention uses a gas check valve 18 to ensure the one-way discharge of the residual gas.

[0032] Compared with the prior art, the present invention combines physical and chemical means in the biochar production line to prepare biochar with high adsorption performance, while improving the problems of the carbonization process that cannot be produced continuously, low efficiency, uneven heating, unstable quality, low product adsorption performance, and single function. By adding a modifier reaction zone, biochar with different adsorption characteristics can be prepared as needed. The application of segmented biochar pyrolysis equipment can effectively eliminate the influence of biological thermal pyrolysis gas on biochar yield and quality. BRIEF DESCRIPTION OF THE DRAWINGS

[0033] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings required for use in the embodiments or the description of the prior art will be briefly introduced below. Obviously, the drawings in the following description are only embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on the provided drawings without creative work.

[0034] Figure 1 It is a three-dimensional schematic diagram of the continuous multi-stage auger-type modified biochar complete set of equipment of the present invention.

[0035] Figure 2It is a cross-sectional schematic diagram of the continuous multi-stage auger-type modified biochar complete set of equipment of the present invention.

[0036] Figure 3 This is the SEM image of wheat straw raw material and biochar before and after steam explosion in Experimental Example 1 of the present invention.

[0037] Figure 4 This is the infrared spectrum of wheat straw biochar at 450°C before and after modification in Experimental Example 1 of the present invention.

[0038] Figure 5 This is the adsorption amount of heavy metal lead solution by wheat straw biochar at 450°C before and after modification in Experimental Example 1 of the present invention. DETAILED DESCRIPTION

[0039] The technical solutions in the embodiments of the present invention will be described clearly and completely below in conjunction with the accompanying drawings. Obviously, the described embodiments are only 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.

[0040] like Figure 1 , Figure 2 As shown, 1 is the equipment shell, 2 is the special-shaped augers, 3 is the drying and preheating zone, 4 is the main reaction zone, 5 is the modification zone, 6 is the stabilization zone, 7 is the temperature-resistant baffle, 8 is the feed port, 9 is the modifier feed port, 10 is the temperature control component, 11 is the water vapor discharge port, 12 is the gas one-way valve, 13 is the conveyor belt, 14 is the steam explosion pretreatment system, 15 is the cracking gas discharge port, 16 is the gas one-way valve, 17 is the residual gas discharge port, 18 is the gas one-way valve, 19 is the U-shaped augers, 20 is the U-shaped augers, 21 is the cylindrical augers, 22 is the circular augers, and 23 is the discharge port.

[0041] The steam explosion pretreatment system 14 uses a closed device for heating steam to heat the target pressure. After maintaining the pressure for a certain period of time, the steam ejection principle is used to complete the instantaneous ejection steam explosion machine to explode the biomass raw material. Since the explosion is completed in a millisecond, the water vapor undergoes adiabatic expansion and works, converting the steam internal energy into mechanical energy and acting on the biomass tissue cell layers, thereby increasing the explosion energy density and fully decomposing the material, shortening the steam pressure holding time from more than ten minutes to tens of seconds, and no chemical addition is required, which not only saves steam energy consumption, but also improves the production capacity of the equipment.

[0042] The conveyor belt 13 and the feed port 8 constitute the feed part of the present invention. The conveyor belt 13 is connected to the discharge end of the steam explosion pretreatment system 14, and the material is transported to the feed port 8 located at the feed end of the drying and preheating zone 3 through the conveyor belt, so that the material enters the reaction zone.

[0043] The drying and preheating zone 3, the main reaction zone 4, the modification zone 5 and the stabilization zone 6 constitute the reaction zone of the present invention. Each reaction zone is separated by a temperature-resistant partition 7, and the temperature of each reaction zone is adjusted separately by a temperature control component 10 in the working state.

[0044] The augers 19 to 22 constitute the material transfer part of the present invention. By controlling the augers rotation speed and the outer diameter of each augers, the conveying speed of the material in each reaction zone is controlled to ensure the retention time of the material in each reaction zone.

[0045] The gas one-way valves 12, 16 and 18 constitute the pressure control sealing part of the present invention, which ensures good sealing of the system, provides an oxygen-free or oxygen-deficient state for the pyrolysis and carbonization reaction of the material, and is also used to ensure pressure control of the equipment system to ensure process safety.

[0046] During operation, the biomass raw material is first pretreated by the steam explosion pretreatment system 14, and then sent to the feed port 8 through the conveyor belt 13 to enter the drying preheating zone 3 for drying and carbonization. The drying preheating temperature is adjusted by the temperature control component 10, and the rear end water vapor discharge port 11 is opened during the heating process. After a certain period of reaction, it is transported to the main reaction zone 4 to prepare biochar. The main reaction zone 4 is programmed to heat by the temperature control component 10, and the cracking gas discharge port 15 is opened at the same time. After a certain period of reaction, it is transported to the modification zone 5. In the modification zone 5, the modifier is added through the modifier feed port 9 to carry out the modification reaction. The temperature is controlled by the temperature control component 10. After the reaction is completed, it reaches the stabilization zone 6 and is programmed to cool down by the temperature control component 10, and the residual gas discharge port 17 is opened at the same time. After cooling, the material is discharged through the discharge port 23 to obtain modified biochar.

[0047] In order to better understand the present invention, the present invention is further specifically described below through the following examples, but it should not be understood as a limitation of the present invention. Some non-essential improvements and adjustments made by technicians in this field based on the above invention content are also considered to fall within the protection scope of the present invention.

[0048] Example 1

[0049] A complete set of continuous multi-stage agitator-type modified biochar equipment for preparing bentonite / biochar composite materials, the overall length of the equipment is 2.5m, the screw shaft diameter is 45mm, the screw speed is 50r / min, wherein the length of the drying and preheating zone is 0.5m, the outer diameter of the screw is 60mm, and the pitch is 30mm; the length of the main reaction zone is 1.0m, the outer diameter of the screw is 75mm, and the pitch is 60mm; the length of the modification zone is 0.5m, the outer diameter of the screw is 75mm, and the pitch is 60mm; the length of the stabilization zone is 0.5m, the outer diameter of the screw is 60mm, and the pitch is 30mm.

[0050] When applied, first put 30kg of wheat straw less than 3cm long into the steam explosion reactor, pressurize it by passing water vapor, maintain the pressure for 5min after reaching 2.0MPa, and then instantly open the valve of the reactor for steam explosion treatment. The wheat straw after steam explosion treatment is sent to the drying and preheating zone through a conveyor belt for drying and carbonization treatment. The drying and preheating temperature is adjusted to 150℃, and the rear end water vapor discharge port is opened during the heating process. After reacting for 10min, it is transported to the main reaction zone to prepare biochar. The temperature of the main reaction zone is set to 450℃, and it is heated from 150℃ to 450℃ at a heating rate of 30℃ / min. At the same time, the rear end gas discharge port is opened. After reacting for 30min, it is gradually transported to the modification zone. 3kg of bentonite is added to the modification zone for modification reaction. The temperature is set to 450℃. After the reaction is completed, it reaches the stable zone for cooling. After cooling, an improver that can adsorb heavy metals is obtained. The improver can adsorb heavy metal lead and can be used to improve soil contaminated by lead.

[0051] Example 2

[0052] A complete set of continuous multi-stage agitator-type modified biochar equipment for preparing magnet / biochar composite materials, the overall length of the equipment is 2.5m, the screw shaft diameter is 45mm, the screw speed is 80r / min, wherein the length of the drying and preheating zone is 0.5m, the outer diameter of the screw is 60mm, and the pitch is 30mm; the length of the main reaction zone is 1.0m, the outer diameter of the screw is 75mm, and the pitch is 60mm; the length of the modification zone is 0.5m, the outer diameter of the screw is 75mm, and the pitch is 60mm; the length of the stabilization zone is 0.5m, the outer diameter of the screw is 60mm, and the pitch is 30mm.

[0053] When applied, first, 60kg of rice husk powder with a particle size of about 2mm is placed in a steam explosion reactor, and pressurized by passing water vapor. After reaching 1.8MPa, the pressure is maintained for 3min, and then the valve of the reactor is instantly opened for steam explosion treatment. The wheat straw after steam explosion treatment is sent to the drying and preheating area through a conveyor belt for drying and carbonization. Then, the drying and preheating temperature is adjusted to 150℃, and the rear end water vapor discharge port is opened during the heating process. After reacting for 10min, it is transported to the main reaction area to prepare biochar. The temperature of the main reaction zone is set to 550℃, and it is heated from 150℃ to 550℃ at a heating rate of 30℃ / min, and the rear end gas discharge port is opened. After reacting for 25min, it is gradually transported to the modification area. 6kg of ferroferric oxide powder is added to the modification area for modification reaction. The temperature is set to 450℃. After the reaction is completed, it reaches the stable area for cooling. After cooling, an improver that can adsorb heavy metals is obtained. After cooling, an improver that can adsorb heavy metals is obtained. This improver can adsorb heavy metal cadmium and be used to improve cadmium-contaminated soil.

[0054] Example 3

[0055] A complete set of continuous multi-stage agitator-type modified biochar equipment for preparing magnesium oxide / biochar composite materials, the overall length of the equipment is 4.5m, the screw shaft diameter is 45mm, the screw speed is 100r / min, wherein the drying and preheating zone is 1.0m long, the screw outer diameter is 80mm, and the screw pitch is 40mm; the main reaction zone is 1.5m long, the screw outer diameter is 100mm, and the screw pitch is 75mm; the modification zone is 1.0m long, the screw outer diameter is 100mm, and the screw pitch is 75mm; the stabilization zone is 1.0m long, the screw outer diameter is 80mm, and the screw pitch is 40mm.

[0056] When applied, first put 100kg of tomato straw powder with a particle size of 1-2mm into the steam explosion reactor, pressurize it by passing water vapor, maintain the pressure for 8min after reaching 2.0MPa, and then instantly open the valve of the reactor for steam explosion treatment. The wheat straw after steam explosion treatment is sent to the drying and preheating area through a conveyor belt for drying and carbonization. Then, the drying and preheating temperature is adjusted to 125℃, and the rear end water vapor discharge port is opened during the heating process. After reacting for 10min, it is transported to the main reaction area to prepare biochar. The temperature of the main reaction zone is set to 600℃, and it is heated from 125℃ to 600℃ at a heating rate of 30℃ / min, and the rear end gas discharge port is opened. After reacting for 35min, it is gradually transported to the modification area. 10kg of magnesium oxide powder is added to the modification area for modification reaction, and the temperature is set to 450℃. After the reaction is completed, it reaches the stabilization area for cooling. After cooling, the adsorbent can remove phosphorus from phosphorus-rich polluted water. The phosphorus removal rate for polluted water with a phosphate concentration of 30 mg / L reaches 95%. The adsorbent that adsorbs and removes phosphorus can be used as a slow-release phosphate fertilizer.

[0057] In order to further demonstrate the beneficial effects of the present invention and to better understand the present invention, the application performance of the continuous multi-stage agitator-type modified biochar complete set of equipment described in the present invention is further illustrated through the following test experiments, but it should not be understood as a limitation of the present invention. The product properties obtained by other measurement experiments conducted by technicians in this field based on the above-mentioned invention content and the applications based on the above-mentioned properties are also regarded as falling within the protection scope of the present invention.

[0058] Experimental Example 1

[0059] The biochar prepared from the steam-exploded modified wheat straw at 450°C in Example 1 was analyzed by SEM. Figure 3As shown, series A is wheat straw, series B is wheat straw after blasting, series C is wheat straw biochar, and series D is wheat straw biochar after blasting. A1, B1, C1, and D1 are physical pictures, and A2-A4, B2-B4, C2-C4, and D2-D4 are electron microscope pictures magnified 50 times, 500 times, and 5000 times, respectively. It can be seen that after blasting, the wheat straw is destroyed, the fibers are exposed, and the biochar generated after high-temperature carbonization at 450°C has more pores on its surface.

[0060] Furthermore, the present invention uses the ASAP 2460 series fully automatic rapid physical adsorption analyzer to analyze the BET specific surface area and average pore size of the sample. The specific surface area of ​​the blasted modified biochar (SEWS) is nearly 6 times higher than that of the biochar (WS) directly prepared from wheat straw, and the average pore size is reduced (Table 1). On the basis of the blasted biochar (SEWS-BT) modified with a ratio of bentonite to straw of 1:10, the specific surface area is increased to 210 m 2 / g, the average pore size increases slightly, which can effectively increase the adsorption sites.

[0061] The biochar samples were tested by infrared and the infrared spectrum was obtained ( Figure 4 Further analysis revealed that the blasting treatment can significantly increase the OH stretching of wheat straw functional groups (3433 cm -1 ; 3043cm -1 ), while the oxygen-containing functional group -C=OOH (2991cm -1 ), -C=OO-(1596cm -1 ) and -C-OH(1103cm -1 ) will increase the negative Zeta potential, thereby increasing the electrostatic adsorption capacity of biochar. Bentonite reacts with biochar to generate Si-O-Si (867cm -1 ) functional groups, indicating that the reaction was complete, which was beneficial to the adsorption of heavy metals such as lead by SEWS-BT.

[0062] The adsorption performance of heavy metal lead of biochar before and after modification was analyzed ( Figure 5 ), it can be found that the adsorption performance of WS for lead is only 3.8 mg g -1 , while SEWS increased to 12.5 mg g -1 The double-modified SEWS-B has the best adsorption performance for lead, and the adsorption performance for lead reaches 150.0 mg g -1 .

[0063] Table 1 Specific surface area and average pore size of wheat straw treated biochar

[0064]

[0065] The above description of the disclosed embodiments enables one skilled in the art to implement or use the present invention. Various modifications to these embodiments will be apparent to one skilled in the art, and the general principles defined herein may be implemented in other embodiments without departing from the spirit or scope of the present invention. Therefore, the present invention will not be limited to the embodiments shown herein, but rather to the widest scope consistent with the principles and novel features disclosed herein.

Claims

1. A multi-stage auger-type continuous modified biochar production equipment that couples raw material blasting and mineral loading, characterized in that: The device is a multi-stage agitator-type continuous pyrolysis device, comprising a device housing (1), a special-shaped agitator (2), a drying and preheating zone (3), a main reaction zone (4), a modification zone (5) and a stabilization zone (6) arranged in sequence along the axial direction of the device housing (1), wherein the drying and preheating zone (3), the main reaction zone (4), the modification zone (5) and the stabilization zone (6) are respectively separated by a temperature-resisting baffle (7), the special-shaped agitator (2) continuously extends along the axial direction of the device housing (1) and passes through the drying and preheating zone (3), the main reaction zone (4), the modification zone (5) and the stabilization zone (6) arranged in the device housing (1) in sequence, the feeding end of the drying and preheating zone (3) is provided with a feeding port (8), the feeding end of the modification zone (5) is provided with a modifier feeding port (9), and the discharging end of the stabilization zone (6) is provided with a discharging port (23); The discharge end of the drying and preheating zone (3) is provided with a water vapor discharge port (11), and the water vapor discharge port (11) is provided with a first gas one-way valve (12); the discharge end of the main reaction zone (4) is provided with a cracking gas discharge port (15), and the cracking gas discharge port (15) is provided with a second gas one-way valve (16); the discharge end of the stabilization zone (6) is provided with a residual gas discharge port (17), and the residual gas discharge port (17) is provided with a third gas one-way valve (18); The feed end of the drying and preheating zone (3) is connected to a steam explosion pretreatment system (14) via a conveyor belt (13); The drying preheating zone (3) adopts a first U-shaped agitator (19), the first U-shaped agitator (19) has a spiral outer diameter of 30.0≤D≤80.0 mm, a spiral shaft diameter of 15.2-60.0 mm, a screw pitch S of 30.0-100.0 mm, and a drying zone length of 500-1000 mm; the main reaction zone (4) adopts a second U-shaped agitator (20), the second U-shaped agitator (20) has a spiral outer diameter of 45.0≤D≤120.0 mm, a spiral shaft diameter of 15.2-60.0 mm, a screw pitch S of 30.0-150.0 mm, and a main reaction zone length of 800-1500 mm; the modification zone (5) adopts a cylindrical agitator (21), the cylindrical agitator (21) has a spiral outer diameter of 45.0≤D≤120.0 mm, a spiral shaft diameter of 15.2-60.0 mm, a screw pitch S of 30.0-150.0 mm, and a main reaction zone length of 800-1500 mm. mm, the pitch S is 30.0-150.0 mm, and the length of the modified area is 500-1000 mm; the stabilization zone (6) adopts a circular agitator (22), the spiral outer diameter of the circular agitator (22) is 30.0≤D≤80.0 mm, the spiral shaft diameter is 15.2-60.0 mm, the pitch S is 30.0-100.0 mm, the pitch S is 30.0-100.0 mm, and the length of the stabilization zone is 500-1000 mm.

2. The multi-stage auger-type continuous modified biochar production equipment coupling raw material blasting and mineral loading according to claim 1 is characterized in that: It also includes temperature control components (10) independently arranged in the drying and preheating zone (3), the main reaction zone (4), the modification zone (5) and the stabilization zone (6).

3. An application of the multi-stage auger-type continuous modified biochar production equipment coupled with raw material blasting and mineral loading as claimed in claim 1, characterized in that: The steps include: Step 1, start the equipment, set the augers speed, and respectively set the temperatures of the drying and preheating zone (3), the main reaction zone (4), the modification zone (5) and the stabilization zone (6); Step 2: At the start of the reaction, the reaction raw materials are fed into the feed port (8), and the first gas check valve (12) of the steam discharge port (11), the second gas check valve (16) of the cracked gas discharge port (15), and the third gas check valve (18) of the residual gas discharge port (17) are opened; Step 3, adding a modifier through the modifier feed port (9); Step 4: Collect the modified biochar material from the outlet of the stabilization zone.

4. The application of the multi-stage auger-type continuous modified biochar production equipment coupling raw material blasting and mineral loading according to claim 3 is characterized in that: The rotation speed of the special-shaped agitator (2) is 1-100 r / min, the temperature of the drying and preheating zone (3) is controlled at 105-150°C, the temperature of the main reaction zone (4) is controlled at 300-600°C, the temperature of the modification zone (5) is controlled at 300-600°C, and the temperature of the stabilization zone (6) is controlled at 0-50°C.

5. The application of the multi-stage auger-type continuous modified biochar production equipment coupling raw material blasting and mineral loading according to claim 3 is characterized in that: The reaction raw materials include one or more of wheat straw, corn straw, bamboo chips, tomato straw, cotton straw, rice straw, rape straw, coconut shell, peanut shell, shell, and eggshell; the modifier includes one or more of bentonite, montmorillonite, kaolin, calcium carbonate, calcium dihydrogen phosphate, nano-SiO2, magnesium oxide, ferroferric oxide, ferric oxide, and Co-Fe2O4.

6. The use of the multi-stage auger-type continuous modified biochar production equipment coupled with raw material blasting and mineral loading according to claim 3, characterized in that: It also includes steam explosion pretreatment, and the raw materials after steam explosion pretreatment are sent to the drying preheating zone (3).

7. The use of the multi-stage auger-type continuous modified biochar production equipment coupled with raw material blasting and mineral loading according to claim 6, characterized in that: The reaction pressure of the steam explosion is 1.0-2.0 MPa, and the pressure holding time is 60-600 s.

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