System for converting sludge into liquid fuel

Abstract

The utility model discloses a system for converting sludge into liquid fuel. A sludge pretreatment unit is composed of a sludge dewatering treatment device, a sludge crushing device and a sludge screening device, the output end of the sludge dewatering treatment device is communicated with the sludge crushing device, the output end of the sludge crushing device is communicated with the sludge screening device, and the output end of the sludge screening device is communicated with a pyrolysis reactor. The crushed and screened sludge is fed into a pyrolysis reactor, the steam outlet end of the pyrolysis reactor is communicated with a condensing device, after a steam-shaped pyrolysis product is cooled by the condensing device, bio-oil is obtained, the output end of the condensing device is communicated with a liquid fuel impurity removal system, and the output end of the liquid fuel impurity removal system is communicated with a liquid fuel storage box. By optimizing a series of processes of sludge pretreatment, pyrolytic reaction, bio-oil impurity removal and detection and the like, many problems in the prior art are solved, and efficient and environment-friendly conversion of sludge into high-quality liquid fuel is realized.

Description

Technical Field

[0001] This utility model relates to the field of sludge conversion into liquid fuel, specifically to a system for converting sludge into liquid fuel. Background Technology

[0002] Urban sludge production continues to increase with urbanization and the expansion of wastewater treatment capacity. Traditional disposal methods such as landfill and stockpiling not only occupy large amounts of land resources but also easily cause environmental pollution. Converting urban sludge into gaseous, liquid, and solid fuels to achieve its resource utilization is of great significance, as it can alleviate environmental pressure and create economic value. With the acceleration of urbanization and the continuous expansion of wastewater treatment capacity, urban sludge production is increasing daily. Sludge contains not only a large amount of organic matter but also harmful substances such as heavy metals and pathogens. Improper disposal will cause serious environmental pollution. Traditional sludge treatment methods, such as landfill and incineration, have problems such as occupying large amounts of land resources, easily generating secondary pollution, and wasting energy. Therefore, developing an efficient, environmentally friendly sludge treatment technology that enables resource recycling is an urgent practical need.

[0003] Converting sludge into liquid fuel is a highly promising resource recovery approach. By using specific processes to transform the organic components of sludge into liquid fuels such as bio-oil, not only can sludge be reduced and rendered harmless, but economically valuable energy products can also be produced, aligning with the principles of sustainable development. However, existing sludge-to-liquid fuel conversion technologies still face numerous challenges in practical applications. In the sludge pretreatment stage, urban sludge typically has a high water content, which not only increases the difficulty and energy consumption of subsequent treatment but also affects treatment efficiency. Furthermore, sludge may contain various large impurities, such as stones and plastic fragments; if not effectively removed, these can damage subsequent conversion equipment and affect the conversion effect. Bio-oil, as a pyrolysis product, often contains many impurities in its initial state, such as solid particles, moisture, acids, and phenolic compounds. The presence of these impurities severely affects the quality and stability of bio-oil, making it difficult to use directly as fuel or chemical feedstock. For example, solid particles can cause equipment wear and blockage; moisture reduces the calorific value of bio-oil and may trigger hydrolysis reactions; acids and phenolic compounds affect the combustion performance and storage stability of bio-oil. Existing bio-oil impurity removal technologies are either complex and costly, or their impurity removal effects are unsatisfactory, failing to meet the high-quality requirements of actual production. Furthermore, the lack of a comprehensive and accurate bio-oil quality testing system makes it difficult to accurately assess whether bio-oil meets quality standards for use as fuel, thus limiting the large-scale commercial application of sludge-to-liquid fuel technology. Utility Model Content

[0004] Therefore, in order to address the above-mentioned shortcomings, this utility model provides a system for converting sludge into liquid fuel. Through multiple processes such as pretreatment, pyrolysis liquefaction, and impurity removal of sludge (including urban sludge), the system effectively converts urban sludge into liquid fuel. In practical applications, a reasonable conversion path is formed. The impurity removal process strictly controls the quality of the product, ensuring that the produced fuel is safe and efficient, and realizing the unity of resource utilization of urban sludge with environmental and economic benefits.

[0005] This invention is implemented by constructing a system for converting sludge into liquid fuel. The system comprises a sludge dewatering unit, a sludge crushing unit, a sludge screening unit, a pyrolysis reactor, a condensation unit, a liquid fuel temporary storage tank, a liquid fuel impurity removal system, and a liquid fuel storage tank. The sludge pretreatment unit consists of the sludge dewatering unit, the sludge crushing unit, and the sludge screening unit. The output of the sludge dewatering unit is connected to the sludge crushing unit, the output of the sludge crushing unit is connected to the sludge screening unit, and the output of the sludge screening unit is connected to the pyrolysis reactor. The crushed and screened sludge is fed into the pyrolysis reactor. The steam outlet of the pyrolysis reactor is connected to the condensation unit. The vaporous pyrolysis products are cooled by the condensation unit to obtain bio-oil (i.e., liquid fuel). The output of the condensation unit is connected to the liquid fuel impurity removal system, and the output of the liquid fuel impurity removal system is connected to the liquid fuel storage tank. This application solves many problems existing in the prior art by optimizing a series of processes, including sludge pretreatment, pyrolysis reaction, and bio-oil impurity removal and detection, achieving efficient and environmentally friendly conversion of sludge into high-quality liquid fuel.

[0006] According to the present invention, a system for converting sludge into liquid fuel is characterized in that: the sludge dewatering treatment device uses a plate and frame filter press or a centrifugal dewatering machine to perform preliminary dewatering of municipal sludge, reducing the sludge moisture content to 70%-80%. This helps reduce energy consumption in subsequent treatment processes and improves treatment efficiency. After dewatering, the sludge is crushed into suitable particle sizes, controlled at 1-5 cm, using a crusher; subsequently, it is screened by a vibrating screen to remove any large impurities that may be mixed in, such as stones and plastic pieces, ensuring that the sludge texture is uniform and facilitating subsequent conversion processes.

[0007] According to the present invention, a system for converting sludge into liquid fuel is characterized in that: the liquid fuel impurity removal system includes a filter, a heating evaporator, a desiccant adsorption device, an alkaline washing device, an acidic adsorption device, an extraction device, and an adsorption separation device; the inlet end of the filter is connected to a liquid fuel temporary storage tank; the filter, heating evaporator, desiccant adsorption device, alkaline washing device, acidic adsorption device, extraction device, and adsorption separation device are connected in sequence; and the output end of the adsorption separation device is connected to the liquid fuel storage tank.

[0008] According to the present invention, a system for converting sludge into liquid fuel is characterized in that: a filter is used to filter the bio-oil, removing larger solid particulate impurities. This is the first step in impurity removal, which can initially separate visible solid impurities and protect subsequent equipment from wear and clogging. A centrifuge can be installed at the downstream end of the filter, using centrifugal force to separate solid particles and liquid in the bio-oil. For some fine particles that are difficult to remove by filtration, centrifugation can more effectively separate them from the bio-oil, improving the clarity of the bio-oil.

[0009] According to the present invention, a system for converting sludge into liquid fuel is characterized in that: a heating evaporator heats the bio-oil to a certain temperature, causing the water in it to evaporate. The presence of water reduces the calorific value of the bio-oil and may cause hydrolysis and other reactions during storage and use, affecting its stability. Heating and evaporation can reduce the water content in the bio-oil to a certain level. A desiccant adsorption device uses desiccants such as anhydrous sodium sulfate or calcium chloride to adsorb and dehydrate the bio-oil. The desiccant can react chemically or physically with the water in the bio-oil, thereby removing the water. This method is suitable for removing impurities from bio-oil where a high moisture content is required.

[0010] According to the present invention, a system for converting sludge into liquid fuel is characterized in that: an alkaline washing device mixes and stirs bio-oil with alkaline solutions such as sodium hydroxide and sodium carbonate, causing acidic substances to neutralize with the alkali, producing salt and water. Then, through methods such as static stratification or centrifugation, the lower brine phase is separated, thereby removing acidic substances from the bio-oil. Alkaline washing can effectively reduce the acidity of bio-oil and improve its quality.

[0011] The system for converting sludge into liquid fuel according to this utility model is characterized by: acid adsorption using ion exchange resin, which adsorbs and removes acidic substances from bio-oil. The ion exchange resin has specific ion exchange groups that can react with ions in the acidic substances, thereby adsorbing the acidic substances onto the resin. This method has advantages such as high selectivity and simple operation.

[0012] According to the present invention, a system for converting sludge into liquid fuel is characterized in that: the extraction device uses organic solvents such as toluene and dichloromethane to extract phenolic compounds from bio-oil. Phenolic compounds have high solubility in organic solvents; extraction can transfer them from the bio-oil to the organic solvent phase, and then the organic solvent phase and the bio-oil phase are separated to remove the phenolic compounds.

[0013] According to the present invention, a system for converting sludge into liquid fuel is characterized in that: the adsorption separation device uses adsorbents such as activated carbon and silica gel to adsorb phenolic compounds in bio-oil. The adsorbents have a large specific surface area and adsorption activity, and can adsorb phenolic compounds. When bio-oil is passed through the adsorbent bed, the phenolic compounds are adsorbed onto the adsorbent, thereby achieving separation from the bio-oil.

[0014] According to the present invention, a system for converting sludge into liquid fuel is characterized by: a liquid fuel detection system installed between the liquid fuel impurity removal system and the liquid fuel storage tank, used to detect the bio-oil, including its density, viscosity, moisture content, calorific value, and acid value. Density is measured using a densitometer; viscosity is determined using a rotational viscometer; moisture content is detected by Karl Fischer titration; calorific value is determined using an oxygen bomb calorimeter; and acid value is determined by acid-base titration to assess whether the bio-oil meets the quality requirements for use as fuel.

[0015] This utility model has the following advantages: It provides a system for converting sludge into liquid fuel. Through multiple processes such as pretreatment, pyrolysis liquefaction, and impurity removal, the sludge (including urban sludge) is effectively converted into liquid fuel. In practical applications, a reasonable conversion path is formed. The impurity removal process strictly controls the quality of the product, ensuring that the produced fuel is safe and efficient, and realizing the unity of resource utilization of urban sludge and environmental and economic benefits. Attached Figure Description

[0016] Figure 1 This is a diagram showing the overall structure of the system in this application;

[0017] Figure 2 This is a structural diagram of the impurity removal system in this application. Detailed Implementation

[0018] The following will be combined with the appendix Figures 1-2 This utility model will be described in detail, and the technical solutions in the embodiments of this utility model will be clearly and completely described. Obviously, the described embodiments are only some embodiments of this utility model, and not all embodiments. Based on the embodiments of this utility model, all other embodiments obtained by those of ordinary skill in the art without creative effort are within the protection scope of this utility model.

[0019] This invention provides a system for converting sludge into liquid fuel, such as... Figures 1-2As shown, the system can be implemented as follows: The system consists of a sludge dewatering treatment device 1, a sludge crushing device 2, a sludge screening device 3, a pyrolysis reactor 4, a condensation device 5, a liquid fuel temporary storage tank 6, a liquid fuel impurity removal system 7, and a liquid fuel storage tank 8. In this application, the sludge dewatering treatment device 1, the sludge crushing device 2, and the sludge screening device 3 constitute a sludge pretreatment unit. The output end of the sludge dewatering treatment device 1 is connected to the sludge crushing device 2, the output end of the sludge crushing device 2 is connected to the sludge screening device 3, and the output end of the sludge screening device 3 is connected to the pyrolysis reactor 4. The crushed and screened sludge is fed into the pyrolysis reactor 4. The steam outlet end of the pyrolysis reactor 4 is connected to the condensation device 5. The vapor-like pyrolysis products are cooled by the condensation device to obtain bio-oil (i.e., liquid fuel). The output end of the condensation device is connected to the liquid fuel impurity removal system 7, and the output end of the liquid fuel impurity removal system 7 is connected to the liquid fuel storage tank 8. This application addresses many problems in existing technologies by optimizing a series of processes, including sludge pretreatment, pyrolysis reaction, and bio-oil impurity removal and detection, thereby achieving the efficient and environmentally friendly conversion of sludge into high-quality liquid fuel.

[0020] In the implementation of the sludge-to-liquid fuel system described in this application, the sludge dewatering device 1 uses a plate and frame filter press or a centrifugal dewatering machine to initially dewater the municipal sludge, reducing its moisture content to 70%-80%. This helps reduce energy consumption in subsequent treatment processes and improves treatment efficiency. After dewatering, the sludge is crushed into suitable particle sizes, controlled at 1-5 cm, using a crusher; subsequently, it is screened using a vibrating screen to remove any large impurities that may be mixed in, such as stones and plastic pieces, ensuring uniform sludge texture and facilitating subsequent conversion processes.

[0021] In the implementation of the sludge-to-liquid fuel system described in this application; such as Figure 2 As shown, the liquid fuel impurity removal system 7 includes a filter 7-1, a heating evaporator 7-2, a desiccant adsorption device 7-3, an alkaline washing device 7-4, an acidic adsorption device 7-5, an extraction device 7-6, and an adsorption separation device 7-7. The inlet end of the filter 7-1 is connected to the liquid fuel temporary storage tank 6. The filter 7-1, heating evaporator 7-2, desiccant adsorption device 7-3, alkaline washing device 7-4, acidic adsorption device 7-5, extraction device 7-6, and adsorption separation device 7-7 are connected in sequence. The output end of the adsorption separation device 7-7 is connected to the liquid fuel storage tank 8.

[0022] In the implementation of the sludge-to-liquid fuel system described in this application, the pyrolysis reactor 4 employs an external heating method. Upon starting the heating system, the reactor temperature is rapidly raised to 400-600℃. At this high temperature, the organic matter in the sludge undergoes a pyrolysis reaction, decomposing into small molecule compounds. The gaseous, liquid, and solid products generated during the pyrolysis process are discharged through different outlets. The vaporous pyrolysis products, after being cooled by a condenser, yield bio-oil (i.e., liquid fuel). The initially obtained bio-oil contains numerous impurities and requires refining. Methods such as distillation and extraction are used to remove impurities such as water, acids, and solid particles from the bio-oil, improving its quality and making it suitable as fuel oil for use in industrial boilers, internal combustion engines, and other equipment.

[0023] Bio-oil obtained after sludge pyrolysis and cooling typically contains various impurities, such as solid particles, water, organic acids, and phenolic compounds, requiring impurity removal treatment to improve its quality and stability. The following section combines... Figure 2 The impurity removal unit is described below;

[0024] Filter 7-1 filters the bio-oil, removing larger solid particles. This is the first step in impurity removal, initially separating visible solid impurities and protecting downstream equipment from wear and clogging. A centrifuge can be installed downstream of filter 7-1, using centrifugal force to separate solid particles from the liquid in the bio-oil. For fine particles that are difficult to remove by filtration, centrifugation can more effectively separate them from the bio-oil, improving its clarity.

[0025] The heating evaporator 7-2 heats the bio-oil to a certain temperature, causing the moisture to evaporate. The presence of moisture lowers the calorific value of the bio-oil and may cause hydrolysis and other reactions during storage and use, affecting its stability. Evaporation through heating reduces the moisture content of the bio-oil to a certain level. The desiccant adsorption device 7-3 uses desiccants such as anhydrous sodium sulfate or calcium chloride to adsorb and dehydrate the bio-oil. The desiccant can react chemically with or physically adsorb the moisture in the bio-oil, thereby removing the moisture. This method is suitable for removing impurities from bio-oil where a high moisture content is required.

[0026] In the alkaline washing apparatus 7-4, alkaline solutions such as sodium hydroxide and sodium carbonate are mixed and stirred with the bio-oil to neutralize the acidic substances, producing salt and water. Then, the lower brine phase is separated by methods such as static separation or centrifugation, thereby removing the acidic substances from the bio-oil. Alkaline washing effectively reduces the acidity of bio-oil and improves its quality.

[0027] The acid adsorption device 7-5 uses ion exchange resin adsorption to remove acidic substances from bio-oils. Ion exchange resins possess specific ion exchange groups that can react with ions in acidic substances, thereby adsorbing the acidic substances onto the resin. This method offers advantages such as high selectivity and simple operation.

[0028] Extraction unit 7-6 uses organic solvents such as toluene and dichloromethane to extract phenolic compounds from bio-oil. Phenolic compounds have high solubility in organic solvents, and extraction can transfer them from the bio-oil to the organic solvent phase. Then, by separating the organic solvent phase and the bio-oil phase, the phenolic compounds are removed.

[0029] The adsorption separation device 7-7 uses adsorbents such as activated carbon and silica gel to adsorb phenolic compounds in bio-oil. These adsorbents have a large specific surface area and high adsorption activity, enabling them to adsorb phenolic compounds. When bio-oil is passed through the adsorbent bed, the phenolic compounds are adsorbed onto the adsorbent, thus achieving separation from the bio-oil.

[0030] After the above impurity removal process, the purity and quality of the bio-oil are significantly improved, making it suitable for further applications as fuel or chemical feedstock. The impurity removal process may need to be optimized and adjusted according to the specific characteristics of bio-oil from sludge pyrolysis, depending on its origin and properties.

[0031] In the implementation of the sludge-to-liquid fuel system described in this application, a liquid fuel detection system is installed between the liquid fuel impurity removal system 7 and the liquid fuel storage tank 8 to detect the bio-oil, including its density, viscosity, moisture content, calorific value, and acid value. Density is measured using a densitometer; viscosity is determined using a rotational viscometer; moisture content is detected by Karl Fischer titration; calorific value is determined using an oxygen bomb calorimeter; and acid value is determined by acid-base titration to assess whether the bio-oil meets the quality requirements for use as fuel.

[0032] The above description of the disclosed embodiments enables those skilled in the art to make or use the present invention. Various modifications to these embodiments will be readily apparent to those 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 is not to be limited to the embodiments shown herein, but is to be accorded the widest scope consistent with the principles and novel features disclosed herein.

Claims

1. A system for converting sludge into liquid fuel, characterized by; The system is composed of sludge dewatering treatment device (1), sludge crushing device (2), sludge screening device (3), pyrolysis reactor (4), condensing device (5), liquid fuel temporary storage tank (6), liquid fuel impurity removal system (7) and liquid fuel storage tank (8); the sludge pretreatment unit is composed of the sludge dewatering treatment device (1), the sludge crushing device (2) and the sludge screening device (3), the output end of the sludge dewatering treatment device (1) is communicated with the sludge crushing device (2), the output end of the sludge crushing device (2) is communicated with the sludge screening device (3), the output end of the sludge screening device (3) is communicated with the pyrolysis reactor (4), the crushed and screened sludge is sent into the pyrolysis reactor (4), the steam outlet end of the pyrolysis reactor (4) is communicated with the condensing device (5), the pyrolysis product in the form of steam is cooled by the condensing device to obtain bio-oil, the output end of the condensing device is communicated with the liquid fuel impurity removal system (7), the output end of the liquid fuel impurity removal system (7) is communicated with the liquid fuel storage tank (8).

2. The system for converting sludge into liquid fuel according to claim 1, wherein; The sludge dewatering treatment device (1) uses plate and frame filter press or centrifugal dewatering machine to preliminarily dewater the sludge, so that the water content of the sludge is reduced to 70%-80%; the sludge is crushed into appropriate particle size by using a crusher, the particle size is controlled to be 1-5 centimeters, and the sludge is screened by the sludge screening device (3) to remove mixed large impurities.

3. The system for converting sludge into liquid fuel according to claim 1, wherein; The liquid fuel impurity removal system (7) includes filter (7-1), heating evaporator (7-2), drying agent adsorption device (7-3), alkali washing device (7-4), acid adsorption device (7-5), extraction device (7-6) and adsorption separation device (7-7); the inlet end of the filter (7-1) is communicated with the liquid fuel temporary storage tank (6), the filter (7-1), the heating evaporator (7-2), the drying agent adsorption device (7-3), the alkali washing device (7-4), the acid adsorption device (7-5), the extraction device (7-6) and the adsorption separation device (7-7) are sequentially communicated, and the output end of the adsorption separation device (7-7) is communicated with the liquid fuel storage tank (8).

4. The system for converting sludge into liquid fuel according to claim 3, wherein; The filter (7-1) is used for filtering the bio-oil to remove larger solid particle impurities therein; a centrifuge is arranged at the rear end of the filter (7-1), and the centrifugal force of the centrifuge is used to separate the solid particles and the liquid in the bio-oil.

5. The system for converting sludge into liquid fuel according to claim 3, wherein; The heating evaporator (7-2) is used for heating the bio-oil to evaporate the water therein; the drying agent used by the drying agent adsorption device (7-3) is anhydrous sodium sulfate and calcium chloride to adsorb and dewater the bio-oil.

6. The system for converting sludge into liquid fuel according to claim 3, wherein; The alkali washing device (7-4) is used for mixing and stirring sodium hydroxide and sodium carbonate solution with the bio-oil to make acid substances and alkali neutralize to generate salt and water.

7. The system for converting sludge into liquid fuel according to claim 3, wherein; The acid adsorption device (7-5) uses ion exchange resin adsorption to adsorb and remove acid substances in the bio-oil.

8. The system for converting sludge into liquid fuel according to claim 3, wherein; The extraction device (7-6) uses toluene and dichloromethane to extract phenolic compounds in the bio-oil.

9. The system for converting sludge into liquid fuel according to claim 3, wherein; The adsorption separation device (7-7) uses activated carbon and silica gel to adsorb phenolic compounds in the bio-oil.

10. The system for converting sludge into liquid fuel of claim 1, wherein; A liquid fuel detection system is arranged between the liquid fuel impurity removal system (7) and the liquid fuel storage tank (8) to detect the density, viscosity, moisture content, heat value and acid value of the bio-oil.

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