A method for preparing a porous adsorption material by using biomass ash and simultaneously removing heavy metals in flue gas

Abstract

The application provides a method for preparing porous adsorption material by using biomass ash and simultaneously removing heavy metals in flue gas, and belongs to the technical field of solid waste resource utilization and flue gas purification. The method uses primary biomass ash generated by biomass cogeneration as raw material, and after impurity removal, drying and screening grading, the porous adsorption material is obtained by impregnation modification with an activator and section calcination; the adsorption material is added to the flue gas purification section of a biomass boiler, and fully contacts with flue gas containing heavy metals, so that various heavy metal components such as mercury, lead and cadmium in the flue gas are removed, and the saturated adsorption material can be recycled by heat regeneration. The application realizes green and high-value utilization of biomass ash, solves the problem of heavy metal emission in biomass flue gas, and is suitable for the collaborative treatment of solid waste disposal and flue gas purification in biomass thermal power enterprises.

Description

Technical Field

[0001] This invention relates to the field of solid waste resource utilization and flue gas purification technology, specifically to a method for preparing porous adsorption materials using biomass ash and simultaneously removing heavy metals from flue gas. Background Technology

[0002] With the development of the biomass energy industry, the scale of biomass power generation is constantly expanding, generating a large amount of biomass ash during combustion. Currently, most companies handle this ash by outsourcing its disposal, which not only incurs transportation and disposal costs but also leads to resource waste and environmental compliance pressures in the long run. In fact, biomass ash contains various inorganic mineral components and has a porous structure, possessing the basic conditions for processing and transforming into functional materials. Existing disposal methods do not fully utilize this resource value. Meanwhile, the flue gas emitted from biomass boilers contains various heavy metal pollutants, making it a key target for air pollution control. Current common treatment methods often involve purchasing commercial adsorbents for spray removal, which is not only costly to operate but also results in high energy consumption and carbon emissions from the adsorbent production process itself. Existing research largely focuses on the process of preparing adsorbent materials from biomass ash, rarely considering the actual flue gas treatment needs of biomass power plants. The process routes have poor compatibility with existing power plant flue gas systems, making it difficult to achieve synergistic effects between on-site solid waste disposal and flue gas treatment. Meanwhile, most preparation processes employ a one-step calcination method, resulting in insufficient controllability of the pore structure, limited chemical bonding ability of the material to heavy metals, and room for improvement in overall removal efficiency. Currently, a mature integrated process has not yet been developed to simultaneously address the dual challenges of biomass ash disposal and heavy metal removal from flue gas.

[0003] To address this, a method is proposed for preparing porous adsorbent materials using biomass ash and simultaneously removing heavy metals from flue gas. Summary of the Invention

[0004] The present invention aims to solve the problems mentioned in the background art by providing a method for preparing porous adsorbent materials using biomass ash and simultaneously removing heavy metals from flue gas.

[0005] The specific technical solution is as follows: A method for preparing porous adsorbent materials using biomass ash and simultaneously removing heavy metals from flue gas includes the following steps: (1) Biomass ash pretreatment: The raw biomass ash generated in the biomass cogeneration process is subjected to impurity removal, drying and screening in sequence to obtain screened ash with uniform particle size; (2) Ash material modification and activation: Add activator solution to the sieved ash material, stir and mix evenly, and then perform constant temperature impregnation treatment to obtain activated mixture; (3) Calcination and pore forming: The activated mixture is placed under an inert protective atmosphere for segmented calcination treatment. After the calcination product is cooled, washed to neutral and dried, a porous adsorbent material is obtained. (4) Removal of heavy metals from flue gas: The porous adsorbent material is added to the flue gas purification process of the biomass boiler so that the adsorbent material is in full contact with the flue gas containing heavy metals and removes various heavy metal components in the flue gas through adsorption. After the porous adsorbent material is saturated, it is recycled after regeneration treatment or stabilized.

[0006] This solution uses biomass ash generated during biomass power generation as raw material to prepare adsorbent materials, enabling on-site disposal and resource conversion of solid waste, reducing the cost and environmental risks of transporting and disposing of ash and slag off-site. The entire process combines material preparation with flue gas treatment, forming a complete production and application chain. It eliminates the need for additional commercial adsorbent procurement, thus reducing the operating costs of flue gas treatment. After adsorption saturation, the material can be recycled or stabilized. The entire process is clearly defined, compatible with existing biomass power plant production and environmental protection systems, and requires no large-scale equipment modifications, facilitating project implementation and widespread adoption.

[0007] The above-mentioned method for preparing porous adsorbent materials using biomass ash and simultaneously removing heavy metals from flue gas includes the following steps: In step (1), the impurity removal process sequentially employs magnetic separation to remove iron impurities and air classification to remove unburned carbon residue and light impurities; the drying process is carried out at a temperature of 80℃~120℃ for 2h~6h; and the sieving process uses a standard sieve for grading to obtain sieved ash with a particle size of 75μm~250μm. By removing impurities step by step through magnetic separation and air classification, iron impurities and unburned light components in the ash can be removed respectively, improving the purity and uniformity of the ash and avoiding interference from impurities in the subsequent modification process. The drying process can remove free moisture from the ash, ensuring sufficient contact and uniform action between the activator solution and the ash components. The sieving and grading process controls the particle size range of the ash, making the material more uniformly heated and treated during subsequent impregnation and calcination, which helps to reduce the performance differences between different batches of materials and improve the stability of product quality.

[0008] The above-mentioned method for preparing porous adsorbent materials using biomass ash and simultaneously removing heavy metals from flue gas, wherein in step (2), the activator is any one or a combination of potassium hydroxide, sodium hydroxide, sodium carbonate, calcium chloride, and phosphoric acid; the mass concentration of the activator solution is 10% to 40%; and the solid-liquid ratio of the sieved ash to the activator solution is 1:3 to 1:6. Multiple optional activator types can be flexibly selected according to the composition characteristics of the target flue gas and the material performance requirements. Different activators focus on pore etching and active site loading, respectively, and their combined use can take into account both the physical and chemical adsorption capabilities of the material. A reasonable activator concentration range can ensure the effect of modification and activation while avoiding waste and subsequent washing burden caused by excessive reagents. A suitable solid-liquid ratio range can ensure that the ash is completely submerged in the activator solution, so that the activator is uniformly loaded on the surface of the ash particles and inside the pores, avoiding the problem of insufficient or over-activation in certain areas, and improving the consistency of the modification effect.

[0009] The above-mentioned method for preparing porous adsorbent materials using biomass ash and simultaneously removing heavy metals from flue gas includes a step (2) where the temperature of the constant-temperature impregnation treatment is 40℃~80℃, the impregnation time is 1h~4h, and the stirring is continuously carried out at a rate of 100r / min~300r / min during the impregnation process. The constant-temperature impregnation environment can keep the reaction rate between the activator and the active components in the ash stable, avoiding uneven reaction caused by temperature fluctuations. Continuous stirring can prevent the ash from settling and agglomerating, ensuring sufficient contact between the solid and liquid phases, and allowing the activator to penetrate evenly into the pore structure of the ash. The appropriate combination of impregnation time and stirring rate can control the treatment cycle while ensuring sufficient activation, taking into account both the modification depth and treatment efficiency, avoiding poor performance caused by insufficient impregnation, and also preventing process redundancy caused by excessive impregnation.

[0010] The above-mentioned method for preparing porous adsorbent materials using biomass ash and simultaneously removing heavy metals from flue gas includes a step (3) in which the segmented calcination process is divided into two stages: low-temperature pre-calcination and high-temperature activation calcination. The low-temperature pre-calcination temperature is 200℃~400℃, and the holding time is 0.5h~2h. The high-temperature activation calcination temperature is 600℃~900℃, and the holding time is 1h~3h. The heating rate during the calcination process is 8℃ / min~15℃ / min. By adopting the segmented calcination method, the low-temperature pre-calcination stage can gradually remove the residual volatiles and bound water in the ash material, avoiding the rapid escape of gas and destruction of the pore structure when directly entering the high-temperature stage, thus providing a stable matrix for high-temperature activation. The high-temperature activation calcination stage constructs a rich porous structure through the etching effect of the activator, thereby increasing the specific surface area and adsorption capacity of the material. A reasonable heating rate can make the temperature field distribution in the furnace uniform, the material heated evenly, reduce local over-burning or under-burning, help form a regular and controllable channel structure, and improve the batch stability of material performance.

[0011] The above-mentioned method for preparing porous adsorbent materials using biomass ash and simultaneously removing heavy metals from flue gas includes the following steps: In step (3), the inert protective atmosphere is a nitrogen or argon atmosphere with a gas flow rate of 50 mL / min to 200 mL / min; the drying temperature is 100℃ to 150℃, and the drying time is 4h to 8h. The inert protective atmosphere can prevent the oxidation reaction of combustible components in the ash during high-temperature calcination, prevent the material structure from being damaged, and ensure the integrity of the porous skeleton. A suitable gas flow rate can promptly remove the gaseous byproducts generated during the calcination process, maintain the stability of the atmosphere inside the furnace, and avoid byproduct residues affecting the material performance. Washing the calcined product to neutrality before drying can remove residual activators and soluble impurities, avoiding the negative impact of residual components on the subsequent flue gas adsorption process; suitable drying parameters can ensure that the material moisture content meets the standard, and improve the performance stability of the product during storage and use.

[0012] The above-mentioned method for preparing porous adsorbent materials using biomass ash and simultaneously removing heavy metals from flue gas, wherein the porous adsorbent material prepared in step (3) has a specific surface area of ​​80 m² / g to 350 m² / g, a total pore volume of 0.15 cm³ / g to 0.6 cm³ / g, and an average pore size of 2 nm to 20 nm. Having a suitable range of specific surface area and pore volume provides sufficient adsorption sites for heavy metal components, thus enhancing the material's adsorption capacity. The hierarchically distributed pore structure includes both micropores that enable physical adsorption and mesopores that facilitate molecular diffusion, balancing adsorption capacity and adsorption rate. This allows heavy metal components in the flue gas to rapidly diffuse into the pores and be adsorbed, adapting to short-time contact conditions under flue gas flow conditions and exhibiting good adaptability to different forms of heavy metal components.

[0013] The above-mentioned method for preparing porous adsorbent materials using biomass ash and simultaneously removing heavy metals from flue gas, wherein in step (4), the flue gas purification process is set at the inlet of the dust collector of the biomass boiler; the temperature of the flue gas is 120℃~180℃, and the flue gas velocity is 3m / s~8m / s. By setting the adsorbent material addition position at the inlet of the dust collector, the material after adsorption saturation can be captured by the subsequent dust removal equipment along with the dust in the flue gas, without the need to add a separate dedicated adsorbent collection device, and can be directly connected to the existing flue gas purification system of the power plant, reducing the investment in modification and land occupation. A suitable flue gas temperature range can ensure the adsorption activity of the adsorbent material and avoid the re-desorption of adsorbed heavy metals due to excessively high temperature, maintaining a stable removal effect. A reasonable flue gas velocity can ensure that the adsorbent material remains in a suspended and dispersed state in the flue, prolonging the effective contact time and improving the contact efficiency of the gas and solid phases.

[0014] The above-mentioned method for preparing porous adsorbent materials using biomass ash and simultaneously removing heavy metals from flue gas includes the following steps: In step (4), the porous adsorbent material is added by pneumatic injection, with the mass-to-volume ratio of the added amount to the flue gas flow rate being 50 mg / m³ to 300 mg / m³; the residence time of the adsorbent material in the flue gas is 2 s to 8 s. Using pneumatic injection allows the adsorbent material to disperse rapidly in the flue gas, forming a uniform gas-solid mixture system and increasing the contact area between the adsorbent material and the heavy metal components. The added amount can be flexibly adjusted according to the concentration level of heavy metals in the flue gas, controlling material consumption while ensuring treatment effectiveness. A suitable residence time ensures that the adsorbent material and the heavy metal components in the flue gas fully interact, making the adsorption process more thorough and improving the overall removal effect, while avoiding excessive residence time that could increase flue resistance and system energy consumption.

[0015] The above-described method for preparing porous adsorbent materials using biomass ash and simultaneously removing heavy metals from flue gas includes step (4) where the heavy metal components in the flue gas are one or more of mercury, lead, cadmium, arsenic, and chromium. The prepared adsorbent material combines physical adsorption and chemical chelation, and can simultaneously adsorb various common heavy metal components in flue gas without requiring separate treatment units for each heavy metal. For biomass flue gas with complex compositions, a single process can achieve synergistic treatment of multiple heavy metals, simplifying the flue gas purification process, improving the applicability and comprehensive treatment capabilities of the process, and adapting to different fuel sources and different compositions of biomass flue gas.

[0016] The above-mentioned method for preparing porous adsorbent materials using biomass ash and simultaneously removing heavy metals from flue gas includes a step (4) in which the regeneration process is carried out using a thermal regeneration method. The regeneration temperature is 350℃~550℃, and the regeneration time is 30min~90min. After the porous adsorbent material is saturated, it is returned to the flue gas purification process for recycling. The thermal regeneration method for treating the saturated material is simple and can be implemented using the existing heat source of the power plant without the need for complex regeneration equipment. The appropriate regeneration temperature range can desorb and separate the adsorbed heavy metal components without damaging the porous structure and active sites of the material itself, ensuring that the regenerated material still has good adsorption performance. The regenerated material can be returned to the flue gas purification process for recycling, which can significantly reduce the overall consumption of adsorbent materials, reduce the amount of waste material generated, and further reduce the operating cost and environmental impact of the process.

[0017] The present invention has the following beneficial effects: This application describes a method for preparing adsorbent materials using ash residue produced by biomass power plants as raw material. This method enables on-site conversion and disposal of solid waste, eliminating the transportation and processing costs associated with traditional off-site disposal and reducing the environmental risks associated with solid waste stockpiling or off-site transportation. The prepared adsorbent material is modified and porous based on the original ash residue framework, possessing both physical adsorption and chemical bonding capabilities. It exhibits excellent removal effects on various heavy metal components in flue gas and is well-suited to the complex composition of biomass flue gas.

[0018] The entire process can be directly integrated into the existing dust removal system of the power plant, without the need for additional large-scale specialized equipment. This minimizes the investment required for retrofitting and facilitates rapid deployment on existing production lines. The adsorbent material is prepared from self-produced solid waste, replacing commercially available adsorbents. Furthermore, after adsorption saturation, it can be reused through regeneration, significantly reducing material consumption and operating costs for flue gas treatment.

[0019] The entire process forms a complete chain from solid waste generation to material preparation, then to flue gas treatment, and finally material recycling. It reduces both solid waste emissions and flue gas pollutant emissions, with no additional secondary pollutants generated throughout the process. This aligns with the principles of circular economy and green production, and can help companies improve their environmental benefits and overall profitability. Attached Figure Description

[0020] Figure 1 The flowchart illustrates a method for preparing porous adsorbent materials using biomass ash and simultaneously removing heavy metals from flue gas, as provided in an embodiment of the present invention. Detailed Implementation

[0021] The technical solution of the present invention will be further described below with reference to the accompanying drawings and specific embodiments.

[0022] The accompanying drawings are for illustrative purposes only and are schematic diagrams, not actual images. They should not be construed as limiting the scope of this application. To better illustrate the embodiments of the present invention, some parts in the drawings may be omitted, enlarged, or reduced, and do not represent the actual dimensions of the product. It is understandable to those skilled in the art that some well-known structures and their descriptions may be omitted in the drawings.

[0023] In the accompanying drawings of the embodiments of the present invention, the same or similar reference numerals correspond to the same or similar components. In the description of the present invention, it should be understood that if terms such as "upper," "lower," "left," "right," "inner," and "outer" indicate the orientation or positional relationship based on the orientation or positional relationship shown in the drawings, they are only for the convenience of describing the present invention and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, the terms used to describe positional relationships in the drawings are only for illustrative purposes and should not be construed as limiting the present application. For those skilled in the art, the specific meaning of the above terms can be understood according to the specific circumstances.

[0024] In the description of this invention, unless otherwise explicitly specified and limited, the term "connection" or similar designation indicating a connection between components should be interpreted broadly. For example, it can refer to a fixed connection, a detachable connection, or an integral part; it can be a mechanical connection or an electrical connection; it can be a direct connection or an indirect connection through an intermediate medium; it can refer to the internal communication between two components or the interaction between two components. Those skilled in the art can understand the specific meaning of the above terms in this invention based on the specific circumstances.

[0025] Reference Figure 1 The following examples are provided in this specific implementation.

[0026] Example 1 The method for preparing porous adsorbent materials using biomass ash and simultaneously removing heavy metals from flue gas described in this embodiment includes the following steps: 1. Take the primary biomass ash produced by a biomass circulating fluidized bed boiler, remove impurities by magnetic separation and air separation, dry it at 100℃ for 4 hours to constant weight, and collect the ash material with a sieve size of 75μm to 150μm by sieving.

[0027] 2. Prepare a 20% potassium hydroxide solution by mass. Add the sieved ash to the solution at a solid-liquid ratio of 1:4. After stirring evenly, place the mixture in a 60℃ water bath for 2 hours with a stirring rate of 200 r / min to obtain an activated mixture.

[0028] 3. Transfer the activated mixture into a tube furnace, purge with nitrogen at a flow rate of 100 mL / min; heat to 300℃ at a rate of 10℃ / min and hold for 1 h, then heat to 750℃ and hold for 2 h; after cooling, wash with water until neutral, and dry at 120℃ for 6 h to obtain the porous adsorbent material.

[0029] According to BET method testing, the material has a specific surface area of ​​216 m² / g, a total pore volume of 0.38 cm³ / g, and an average pore size of 8.2 nm.

[0030] 4. The adsorbent material was injected into the flue gas duct before a biomass boiler dust collector at a dosage of 150 mg / m³. The flue gas temperature was 140℃, the flue gas velocity was 5 m / s, and the residence time was 4 s. The main heavy metals in the flue gas were mercury, lead, and cadmium.

[0031] Atomic absorption spectrophotometry analysis showed that the removal efficiency of mercury in the flue gas was 86%, lead 91%, cadmium 88%, and total heavy metals 89%. After thermal regeneration at 450℃ for 60 minutes, the adsorption performance of the saturated adsorption material recovered to 90%, and after five cycles, the performance still maintained more than 82% of the initial value.

[0032] Example 2 The method for preparing porous adsorbent materials using biomass ash and simultaneously removing heavy metals from flue gas described in this embodiment includes the following steps: 1. Take the primary biomass ash produced by a biomass circulating fluidized bed boiler, remove impurities by magnetic separation and air separation, dry it at 80℃ for 6 hours to constant weight, and collect the ash material with a size of 100μm to 200μm by sieve.

[0033] 2. Prepare a 30% (w / w) mixed activation solution of calcium chloride and sodium carbonate with a mass ratio of 1:1. Add the sieved ash to the solution with a solid-liquid ratio of 1:6. After stirring evenly, place the solution in a 50°C water bath for 3 hours with a stirring rate of 150 r / min to obtain the activated mixture.

[0034] 3. Transfer the activated mixture into a tube furnace, purge with argon gas at a flow rate of 120 mL / min; heat to 250 °C at a rate of 8 °C / min and hold for 1.5 h, then heat to 800 °C and hold for 1.5 h; after cooling, wash with water until neutral, and dry at 110 °C for 7 h to obtain the porous adsorbent material.

[0035] According to BET method testing, the material has a specific surface area of ​​182 m² / g, a total pore volume of 0.31 cm³ / g, and an average pore size of 11.5 nm.

[0036] 4. The adsorbent material was injected into the flue gas duct before a biomass boiler dust collector at a dosage of 200 mg / m³. The flue gas temperature was 160℃, the flue gas velocity was 6 m / s, and the residence time was 3 s. The main heavy metals in the flue gas were lead, arsenic, and chromium.

[0037] Atomic absorption spectrophotometry analysis showed that the lead removal efficiency in the flue gas was 89%, the arsenic removal efficiency was 83%, the chromium removal efficiency was 85%, and the total heavy metal removal efficiency was 86%. After the saturated adsorption material was regenerated at 500℃ for 50 minutes, the adsorption performance recovery rate was 87%, and after 5 cycles of use, the performance still maintained more than 80% of the initial value.

[0038] Example 3 The method for preparing porous adsorbent materials using biomass ash and simultaneously removing heavy metals from flue gas described in this embodiment includes the following steps: 1. Take the primary biomass ash produced by a biomass circulating fluidized bed boiler, remove impurities by magnetic separation and air separation, dry it at 120℃ for 2 hours to constant weight, and collect the ash material with a size of 150μm to 250μm by sieve.

[0039] 2. Prepare a 15% phosphoric acid solution by mass. Add the sieved ash to the solution at a solid-liquid ratio of 1:3. After stirring evenly, place the solution in a 70℃ water bath for 1.5 hours with a stirring rate of 250 r / min to obtain an activated mixture.

[0040] 3. Transfer the activated mixture into a tube furnace, purge with nitrogen at a flow rate of 80 mL / min; heat to 350℃ at a rate of 12℃ / min and hold for 0.8 h, then heat to 650℃ and hold for 2.5 h; after cooling, wash with water until neutral, and dry at 140℃ for 5 h to obtain the porous adsorbent material.

[0041] According to BET method testing, the material has a specific surface area of ​​128 m² / g, a total pore volume of 0.22 cm³ / g, and an average pore size of 15.3 nm.

[0042] 4. The adsorbent material was injected into the flue gas duct before a biomass boiler dust collector at a dosage of 100 mg / m³. The flue gas temperature was 130℃, the flue gas velocity was 4 m / s, and the residence time was 6 s. The main heavy metals in the flue gas were mercury and cadmium.

[0043] Atomic absorption spectrophotometry analysis showed that the removal efficiency of mercury in the flue gas was 82%, the removal efficiency of cadmium was 85%, and the removal efficiency of total heavy metals was 83%. After thermal regeneration at 400℃ for 80 minutes, the adsorption performance of the saturated adsorption material recovered to 88%, and after five cycles of use, the performance still maintained more than 81% of the initial value.

[0044] In summary, the working principle of the method for preparing porous adsorbent materials using biomass ash and simultaneously removing heavy metals from flue gas provided in this embodiment is as follows: In the material preparation stage, biomass ash itself contains inorganic components such as silicon and calcium, and has a natural porous framework structure. After impurity removal, drying and sieving, the purity and particle size uniformity of the ash are improved. The ash is mixed and impregnated with an activator solution, and the activator gradually penetrates into the pores and particle surface of the ash. Then, it is calcined in stages. In the low-temperature stage, the residual volatiles and moisture in the ash are removed first to avoid the rapid escape of gas at high temperature and damage to the pore structure. In the high-temperature stage, the activator reacts with the components in the ash to etch and expand the original pores, while constructing new pore structures. It also leaves active sites on the material surface that can bind to heavy metals, and finally forms an adsorbent material with a hierarchical pore structure.

[0045] During the flue gas purification stage, after the adsorbent material is sprayed into the flue, it disperses in the flue gas. Heavy metal molecules in the flue gas are physically adsorbed by diffusing into the pores of the material and being trapped by the pore structure. Simultaneously, they bind to active sites on the material surface, chemically fixing them onto the material, thus removing heavy metals from the flue gas. Once saturated, the material is regenerated by heating. The heavy metals adsorbed on the pores and sites are desorbed and separated by heat, restoring the material's adsorption capacity, allowing it to be returned to the flue for continued use.

[0046] Furthermore, the application of this method involves two steps: preparation of adsorbent materials and removal of heavy metals from flue gas.

[0047] The preparation process begins by collecting raw ash from biomass boiler combustion. The ash is first removed by magnetic separation and air separation to remove iron impurities and light carbon residues. Then, it is dried to remove free moisture and sieved to obtain ash of suitable particle size. Next, an activator solution of appropriate concentration is prepared, and the ash is added to the solution in a specific ratio. The mixture is stirred and impregnated under constant temperature to obtain an activated mixture. This mixture is then fed into a calcination device, protected with inert gas, and calcined according to a staged heating procedure. After calcination, the material is cooled, washed until neutral, and then dried again to obtain the finished porous adsorbent material.

[0048] In the application stage, the prepared adsorbent material is sent into the flue at the front end of the biomass boiler dust collector by pneumatic injection, so that the material is fully mixed and contacted with the flue gas, and the heavy metals in the flue gas are adsorbed and removed by the material. The adsorbed material enters the subsequent dust removal equipment with the flue gas and is captured and collected. The saturated material after collection is sent to the regeneration equipment for thermal regeneration. The regenerated material can be injected back into the flue for recycling. The material that cannot be regenerated further is safely disposed of after stabilization treatment.

[0049] The above are merely preferred embodiments of the present invention and are not intended to limit the implementation methods and protection scope of the present invention. Those skilled in the art should recognize that any equivalent substitutions and obvious changes made based on the description and illustrations of the present invention should be included within the protection scope of the present invention.

Claims

1. A method for preparing porous adsorbent materials using biomass ash and simultaneously removing heavy metals from flue gas, characterized in that, Includes the following steps: (1) Biomass ash pretreatment: The raw biomass ash generated in the biomass cogeneration process is subjected to impurity removal, drying and screening in sequence to obtain screened ash with uniform particle size; (2) Ash material modification and activation: Add activator solution to the sieved ash material, stir and mix evenly, and then perform constant temperature impregnation treatment to obtain activated mixture; (3) Calcination and pore forming: The activated mixture is placed under an inert protective atmosphere for segmented calcination treatment. After the calcination product is cooled, washed to neutral and dried, a porous adsorbent material is obtained. (4) Removal of heavy metals from flue gas: The porous adsorbent material is added to the flue gas purification process of the biomass boiler so that the adsorbent material is in full contact with the flue gas containing heavy metals and removes various heavy metal components in the flue gas through adsorption. After adsorption saturation, porous adsorption materials can be recycled after regeneration or stabilized.

2. The method for preparing porous adsorbent materials using biomass ash and simultaneously removing heavy metals from flue gas according to claim 1, characterized in that, In step (1), the impurity removal process sequentially uses magnetic separation to remove iron impurities and air separation to remove unburned carbon residue and light impurities; the drying process is performed at a temperature of 80℃~120℃ and a drying time of 2h~6h; the sieving process is performed using a standard sieve to classify the material and obtain sieved ash with a particle size of 75μm~250μm.

3. The method for preparing porous adsorbent materials using biomass ash and simultaneously removing heavy metals from flue gas according to claim 1, characterized in that, In step (2), the activator is any one or a combination of potassium hydroxide, sodium hydroxide, sodium carbonate, calcium chloride, and phosphoric acid; the mass concentration of the activator solution is 10% to 40%; and the solid-liquid ratio of the sieved ash to the activator solution is 1:3 to 1:

6.

4. The method for preparing porous adsorbent materials using biomass ash and simultaneously removing heavy metals from flue gas according to claim 1, characterized in that, In step (2), the temperature of the constant temperature impregnation treatment is 40℃~80℃, the impregnation time is 1h~4h, and the stirring is continuously carried out at a rate of 100r / min~300r / min during the impregnation process.

5. The method for preparing porous adsorbent materials using biomass ash and simultaneously removing heavy metals from flue gas according to claim 1, characterized in that, In step (3), the segmented calcination process is divided into two stages: low-temperature pre-calcination and high-temperature activation calcination. The temperature of the low-temperature pre-calcination is 200℃~400℃, and the holding time is 0.5h~2h. The temperature of the high-temperature activation calcination is 600℃~900℃, and the holding time is 1h~3h. The heating rate of the calcination process is 8℃ / min~15℃ / min.

6. The method for preparing porous adsorbent materials using biomass ash and simultaneously removing heavy metals from flue gas according to claim 1, characterized in that, In step (3), the inert protective atmosphere is nitrogen or argon, and the gas flow rate is 50 mL / min to 200 mL / min; the drying temperature is 100℃ to 150℃, and the drying time is 4h to 8h.

7. The method for preparing porous adsorbent materials using biomass ash and simultaneously removing heavy metals from flue gas according to claim 1, characterized in that, The porous adsorbent material prepared in step (3) has a specific surface area of ​​80 m² / g to 350 m² / g, a total pore volume of 0.15 cm³ / g to 0.6 cm³ / g, and an average pore size of 2 nm to 20 nm.

8. The method for preparing porous adsorbent materials using biomass ash and simultaneously removing heavy metals from flue gas according to claim 1, characterized in that, In step (4), the flue gas purification process is set at the inlet of the dust collector of the biomass boiler; the temperature of the flue gas is 120℃~180℃ and the flue gas velocity is 3m / s~8m / s.

9. The method for preparing porous adsorbent materials using biomass ash and simultaneously removing heavy metals from flue gas according to claim 1, characterized in that, In step (4), the porous adsorbent material is added by pneumatic injection, and the mass-volume ratio of the added amount to the flue gas flow rate is 50 mg / m³ to 300 mg / m³; the residence time of the adsorbent material in the flue gas is 2 s to 8 s.

10. The method for preparing porous adsorbent materials using biomass ash and simultaneously removing heavy metals from flue gas according to claim 1, characterized in that, In step (4), the heavy metal components in the flue gas are one or more of mercury, lead, cadmium, arsenic and chromium.

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