Sludge and biomass forming method

Abstract

The invention belongs to the field of organic solid waste resource utilization, and particularly relates to a sludge and biomass forming method. The method comprises the steps that sludge and biomass are mixed and then placed in an anaerobic environment for pyrolysis, the sludge and the biomass are bonded and formed through an oxygen-enriched binder formed through thermal cracking of the sludge and the biomass in the anaerobic environment, and the forming material suitable for fixed bed pyrolysis gasification is prepared. According to the present invention, the oxygen-rich liquid component generated by pyrolysis of the sludge and the biomass in the anaerobic environment is adopted as the natural binder, the mixed molding material meeting the fixed bed pyrolysis gasification requirement is prepared through in-situ molding, the traditional high-cost and high-pollution starch or coal pitch binder is replaced, the production cost is significantly reduced, and the environmental pollution is reduced.

Description

Technical Field

[0001] This invention belongs to the field of organic solid waste resource utilization, specifically relating to a method for forming sludge and biomass. Background Technology

[0002] Municipal and industrial sewage sludge is characterized by high water content and complex heavy metal composition. Traditional sludge treatment methods are insufficient for achieving sustainable treatment and disposal. Common agricultural and forestry wastes, including chili stalks, tobacco stalks, and rice husks, possess abundant biomass resource potential, but their current resource utilization rate is low. There is an urgent need to develop effective biomass and sludge resource utilization pathways to achieve efficient conversion and sustainable management.

[0003] Fixed-bed pyrolysis gasification technology, as a highly efficient and promising thermochemical conversion method, has demonstrated enormous potential in the field of energy conversion. It can convert sludge and biomass raw materials into high-value-added energy products, such as combustible gases and bio-oils, under specific pyrolysis gasification conditions, thereby realizing the energy utilization of waste and providing new ideas and approaches for solving the treatment problems of sludge and agricultural and forestry waste. However, despite the many advantages of fixed-bed pyrolysis gasification technology, in practical applications, the raw materials entering the furnace need to be shaped, and this technology has very strict requirements on the mechanical strength of the shaped raw materials. Under existing process conditions, the co-forming process of sludge and biomass faces a series of significant challenges, such as: (1) Dependence on binders: Traditional molding processes rely on external binders such as starch, coal tar pitch or synthetic resin. While coal tar pitch has excellent bonding properties, it releases carcinogenic substances such as polycyclic aromatic hydrocarbons (PAHs) during pyrolysis, posing an environmental pollution risk. Starch binders are expensive and have poor water resistance, making them difficult to meet the needs of continuous industrial production.

[0004] (2) Insufficient strength of raw material co-forming: The physicochemical properties of sludge and biomass are significantly different. When directly mixed and formed, the particle strength is low due to uneven composition and insufficient bonding force, which cannot meet the requirements of fixed bed pyrolysis gasification equipment for the raw material's resistance to breakage and durability. Summary of the Invention

[0005] To address the problem that existing fixed-bed pyrolysis gasification processes rely on external binders for the molding of sludge and biomass, resulting in low strength after molding, this invention utilizes an oxygen-rich binder generated by co-heating sludge and biomass in an oxygen-free environment. This binder is used to in-situ composite mold sludge and biomass, resulting in high-strength materials suitable for the production of combustible gas from sludge and biomass through fixed-bed pyrolysis gasification.

[0006] Specifically, the solution disclosed in this invention is as follows: A method for molding sludge and biomass includes: utilizing the high oxygen content and complementarity of sludge and biomass, mixing sludge and biomass and then pyrolyzing them in an oxygen-free environment; using an oxygen-rich binder formed by the pyrolysis of sludge and biomass in the oxygen-free environment to bind the sludge and biomass into a molded material, thereby preparing a molded material suitable for fixed-bed pyrolysis and gasification, and the resulting molded material has high strength. The method specifically includes the following steps: Step 1: Crush the dried sludge and biomass; the sludge includes municipal sludge and industrial sludge, the moisture content of the dried sludge is 10-20%, and the particle size of the crushed sludge is less than 5mm. The biomass includes chili stalks and tobacco stalks, the moisture content of the biomass is below 10%, and the particle size of the crushed biomass is less than 10mm.

[0007] Step 2: Mix sludge and biomass at a dry basis mass ratio of 1:9-9:1, and heat to 350-400℃ in an anaerobic environment for 30-120 minutes. The pyrolysis in Step 2 can be carried out in a high-pressure reactor. The anaerobic environment can be provided by an inert gas. The heating rate is 3℃ / min. At 350-400℃, the weak bond structure of the sludge or biomass breaks down, releasing some gas and oxygen-rich liquid. The oxygen-rich liquid can act as a binder to bond different powders into shape. The release of gas from the inside out promotes the development of the pore structure of the sludge or biomass particles, increasing the specific surface area of ​​the particles and providing favorable conditions for improving the subsequent fixed-bed pyrolysis gasification rate. The released gas can be incorporated into the combustible gas produced during subsequent fixed-bed pyrolysis gasification, avoiding resource waste. Furthermore, the oxygen-rich liquid, acting as a binder, can be converted into high-value substances such as combustible gas during subsequent fixed-bed pyrolysis gasification, avoiding environmental pollution and resource waste.

[0008] In addition, step 2 involves stirring the sludge and biomass during the pyrolysis process. The stirring time is 10-30 minutes. During the stirring process, the oxygen-rich liquid produced by the pyrolysis of sludge and biomass acts as a binder to bond the sludge and biomass particles that are in contact with each other. Because each particle of sludge and biomass produces oxygen-rich binder under the action of heat, the binder is evenly distributed in the forming mixture during this process, "seamlessly" bonding each particle. The particles continuously bond, agglomerate, and grow into shape, forming a sludge and biomass mixture.

[0009] Step 3: Molding the mixture obtained in Step 2. Specifically, before molding, the mixture is cooled to room temperature and then placed in molding equipment (such as a briquetting machine and an extruder) for molding. Depending on the required shape (such as cylindrical, square, etc.), a molding material suitable for fixed-bed pyrolysis gasification can be manufactured. The molded material has high strength.

[0010] The beneficial effects of this invention are as follows: 1. This invention utilizes the oxygen-rich liquid component generated by the pyrolysis of sludge and biomass in an oxygen-free environment as a natural binder to prepare a mixed molding material that meets the requirements of fixed-bed pyrolysis and gasification in situ. This material replaces traditional high-cost and high-pollution starch-based or coal tar pitch binders, significantly reducing production costs and environmental pollution.

[0011] 2. This invention enhances the strength of the formed material by optimizing the ratio of sludge, biomass, and binder, thus meeting the application requirements of fixed-bed pyrolysis gasification. Simultaneously, this method reduces production costs, transforming municipal or industrial sludge and biomass into high-value-added binders, forming a circular economy model of "treating waste with waste."

[0012] 3. The method of this invention for preparing shaped materials effectively solves the problem of insufficient mechanical strength of raw materials in existing sludge and biomass fixed-bed pyrolysis gasification technologies.

[0013] 4. This invention utilizes the oxygen-rich liquid generated from the pyrolysis of sludge and biomass to promote the uniform aggregation, cohesion, and growth of different particles in a high-pressure closed reactor, providing a binder for the next step of material forming and avoiding powder dust in subsequent work.

[0014] 5. The oxygen-rich liquid generated by the pyrolysis of this invention can be used as a binder for molding raw materials, and can be converted into high-value substances such as combustible gas during subsequent fixed-bed pyrolysis and gasification, thus avoiding environmental pollution and resource waste. Attached Figure Description

[0015] Figure 1 : Molding material of Example 1.

[0016] Figure 2 : Molding material of Example 2.

[0017] Figure 3 : Molding material of Example 3.

[0018] Figure 4 : The molding material of Comparative Example 1.

[0019] Figure 5 : The molding material of Comparative Example 2.

[0020] Figure 6 : The molding material of Comparative Example 3.

[0021] Figure 7 : The molding material of Comparative Example 4.

[0022] Figure 8 Comparison of the strength of the molding materials of Examples 1-3 and Comparative Examples 1-4.

[0023] Figure 9 Elemental analysis diagrams of municipal sludge, chili stalks, and tobacco stalks used in the embodiments. Detailed Implementation

[0024] To make the objectives, technical solutions, and advantages of this invention clearer, the technical solutions of the embodiments of this invention will be clearly described below with reference to the accompanying drawings. Obviously, the described embodiments are only some, not all, of the embodiments of this invention. All other embodiments obtained by those skilled in the art based on the embodiments of this invention without creative effort are within the scope of protection of this invention.

[0025] Example 1: A method for forming sludge and biomass, comprising: Step 1: Crush the municipal sludge with a moisture content of 10% and the chili stalks with a moisture content of 10%; the particle size of the crushed municipal sludge is less than 5 mm and the particle size of the crushed chili stalks is less than 10 mm.

[0026] Step 2: Under a nitrogen atmosphere, the sludge and chili stalks are pyrolyzed in a high-pressure reactor. Specifically, the pulverized sludge and chili stalks are placed in the high-pressure reactor and heated to 400°C at a heating rate of 3°C / min, and held for 120 min. Additionally, the sludge and chili stalks are stirred during the pyrolysis process for 15 min. The dry weight ratio of the sludge to the chili stalks is 3:1.

[0027] Step 3: Press the material into cylindrical blocks in the molding equipment.

[0028] The resulting molded material is as follows Figure 1 As shown, the particle size is 20 mm and the length is 15 mm. The average compressive strength of the resulting molded material is 1224.94 N.

[0029] Example 2: A method for forming sludge and biomass, comprising: Step 1: Crush the municipal sludge with a moisture content of 10% and the chili stalks with a moisture content of 10%; the particle size of the crushed municipal sludge should be less than 5mm and the particle size of the crushed chili stalks should be less than 10mm.

[0030] Step 2: Under a nitrogen atmosphere, the sludge and chili stalks are pyrolyzed in a high-pressure reactor. Specifically, the pulverized sludge and chili stalks are placed in the high-pressure reactor, and the temperature is increased to 380 °C at a rate of 3 °C / min and maintained for 120 min. Additionally, the sludge and chili stalks are stirred during the pyrolysis process for 10 min. The dry weight ratio of the sludge to the chili stalks is 5:1.

[0031] Step 3: Press the material into cylindrical blocks in the molding equipment.

[0032] The resulting molded material is as follows Figure 2 As shown, the particle size is 20 mm and the length is 15 mm. The average compressive strength of the resulting molded material is 1038.93 N.

[0033] Example 3: A method for forming sludge and biomass, comprising: Step 1: Crush the municipal sludge with a moisture content of 10% and the tobacco stalks with a moisture content of 10%. The particle size of the crushed municipal sludge is less than 5 mm and the particle size of the crushed tobacco stalks is less than 10 mm.

[0034] Step 2: Under a nitrogen atmosphere, the sludge and tobacco stalks are pyrolyzed in a high-pressure reactor. Specifically, the pulverized sludge and tobacco stalks are placed in the high-pressure reactor, and the temperature is increased to 350 °C at a rate of 3 °C / min and maintained for 60 min. Additionally, the sludge and tobacco stalks are stirred during the pyrolysis process for 20 min. The dry weight ratio of the sludge to the tobacco stalks is 2:1.

[0035] Step 3: Press the material into cylindrical blocks in the molding equipment.

[0036] The resulting molded material is as follows Figure 3 As shown, the particle size is 20 mm and the length is 15 mm. The average compressive strength of the resulting molded material is 523.83 N.

[0037] Comparative Example 1: A method for forming sludge and biomass, comprising: Step 1: Crush the municipal sludge with a moisture content of 10% and the chili stalks with a moisture content of 10%. The particle size of the crushed municipal sludge is less than 5 mm, and the particle size of the crushed chili stalks is less than 10 mm.

[0038] Step 2: Mix the crushed sludge and chili stems at a dry weight ratio of 2:1, without adding any binder, and stir in a mixer for 15 minutes.

[0039] Step 3: Press the material into cylindrical blocks in the molding equipment.

[0040] The resulting molded material is as follows Figure 4 As shown, the particle size is 20 mm and the length is 15 mm. The average compressive strength of the resulting molded material is 30.52 N.

[0041] Comparative Example 2: A method for forming sludge and biomass, comprising: Step 1: Crush the municipal sludge with a moisture content of 10% and the chili stalks with a moisture content of 10%. The particle size of the crushed municipal sludge is less than 5 mm, and the particle size of the crushed chili stalks is less than 10 mm.

[0042] Step 2: Under a nitrogen atmosphere, the sludge and chili stalks are pyrolyzed in a high-pressure reactor. Specifically, the pulverized sludge and chili stalks are placed in the high-pressure reactor and heated to 300 °C at a heating rate of 3 °C / min, and held for 120 min. Additionally, the sludge and chili stalks are stirred during the pyrolysis process for 15 min. The dry weight ratio of the sludge to the chili stalks is 3:1.

[0043] Step 3: Press the material into cylindrical blocks in the molding equipment.

[0044] The resulting molded material is as follows Figure 5 As shown, the particle size is 20 mm and the length is 15 mm. The average compressive strength of the resulting molded material is 80.32 N, which is low and does not meet the requirements.

[0045] Comparative Example 3: A method for forming sludge and biomass, comprising: Step 1: Pyrolyze municipal sludge with a moisture content of 10% and tobacco stalks with a moisture content of 10% at 500℃ to prepare semi-coke powder—municipal sludge coke and tobacco stalk coke. The particle size of the municipal sludge coke is less than 5 mm, and the particle size of the tobacco stalk coke is less than 10 mm.

[0046] Step 2: At room temperature, mix municipal sludge coke and tobacco stalk coke at a dry weight ratio of 2:1. Then add 15% (by weight of the total mass of municipal sludge coke and tobacco stalk coke) of coal tar and stir for 20 minutes. The tar is coal tar. Place the mixture in a high-pressure reactor and raise the temperature to 350°C at a rate of 3°C / min and maintain the temperature for 60 minutes. Stir for 20 minutes.

[0047] Step 3: Press the material into cylindrical blocks in the molding equipment.

[0048] The resulting molded material is as follows Figure 6 As shown, the particle size is 20 mm and the length is 15 mm. The average compressive strength of the resulting molded material is 210.8 N, which is low and does not meet the requirements.

[0049] Comparative Example 4: Step 1: Prepare semi-coke powder—municipal sludge coke and tobacco stalk coke—by pyrolyzing municipal sludge with a moisture content of 10% and tobacco stalk coke with a moisture content of 10% at 500℃. The particle size of the municipal sludge coke is less than 5 mm, and the particle size of the tobacco stalk coke is less than 10 mm.

[0050] Step 2: At room temperature, mix municipal sludge sludge coke and tobacco straw coke at a dry weight ratio of 5:1. Then add water equal to 5% of the total mass of the municipal sludge sludge coke and tobacco straw coke and stir for 20 minutes. Place the mixture in a high-pressure reactor and raise the temperature to 380°C at a rate of 3°C / min and maintain the temperature for 120 minutes. Stir for 10 minutes. Step 3: Press the material into cylindrical blocks in the molding equipment.

[0051] The resulting molded material is as follows Figure 7 As shown, the particle size is 20 mm and the length is 15 mm. The average compressive strength of the resulting molded material is 103.52 N, which is low and does not meet the requirements.

[0052] The strength of the molding materials of Examples 1-3 and Comparative Examples 1-4 is compared. Figure 8 As shown. By Figure 8 It can be concluded that the strength of the molding material obtained by the method of the present invention is significantly better than that of the comparative example.

[0053] Figure 9 The elemental analysis of the municipal sludge, chili stalks and tobacco stalks used in the examples showed that the raw materials used were rich in oxygen, which could produce a large amount of oxygen-containing liquid.

[0054] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, and not to limit them; although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some of the technical features; and these modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the spirit and scope of the technical solutions of the embodiments of the present invention.

Claims

1. A method for forming sludge and biomass, characterized in that, include: Sludge and biomass are mixed and then pyrolyzed in an anaerobic environment. The oxygen-rich binder formed by the pyrolysis of sludge and biomass in the anaerobic environment is used to bind the sludge and biomass into a molded material suitable for fixed bed pyrolysis gasification.

2. The sludge and biomass molding method according to claim 1, characterized in that, The method includes the following steps: Step 1: Crush the dried sludge and biomass; Step 2: Mix sludge and biomass at a dry weight ratio of 1:9-9:1, heat to 350-400℃ in an anaerobic environment, and pyrolyze for 30-120 minutes; and stir the sludge and biomass during the pyrolysis process. Step 3: Shape the mixture obtained in Step 2.

3. The sludge and biomass molding method according to claim 2, characterized in that, In step 1, the sludge includes municipal sludge and industrial sludge, and the biomass includes chili stalks and tobacco stalks.

4. The sludge and biomass molding method according to claim 2, characterized in that, In step 1, the moisture content of the dried sludge is 10-20%, and the moisture content of the dried biomass is below 10%.

5. The sludge and biomass molding method according to claim 2, characterized in that, In step 1, the particle size of the biomass after crushing is less than 10 mm, and the particle size of the sludge after crushing is less than 5 mm.

6. The sludge and biomass molding method according to claim 2, characterized in that, In step 2, the pyrolysis is carried out in a high-pressure reactor.

7. The sludge and biomass molding method according to claim 2, characterized in that, In step 2, the oxygen-free environment is provided by an inert gas.

8. The sludge and biomass molding method according to claim 2, characterized in that, In step 2, the heating rate is 3°C / min.

9. A method for forming sludge and biomass according to claim 2, characterized in that, In step 2, the stirring time is 10-30 minutes.

10. A method for forming sludge and biomass according to claim 2, characterized in that, In step 3, the mixture is cooled to room temperature before molding.

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