Production process and system for preparing high-performance lightweight aggregate by using oil sludge and pyrolysis residue

Abstract

This invention discloses a production process and system for preparing high-performance lightweight aggregate using fallen oil sludge and pyrolysis slag. The steps are as follows: Fallen oil sludge and / or pyrolysis slag, fly ash, and bentonite powders are metered according to a specified ratio and then sequentially fed into two twin-shaft mixers connected in series for mixing and staged water addition. The raw ceramsite exiting the twin-shaft mixers is extruded and granulated, then shaped to obtain ceramsite pellets. The ceramsite pellets are first indirectly dried in a rotary indirect dryer to a moisture content of 12-17%, then dried in a belt dryer to a moisture content ≤4%, and finally calcined at high temperature in a rotary kiln. After cooling in a grate cooler, they are screened and stored, yielding the oil sludge ceramsite product. This invention utilizes a combined process technology of a kiln tail heat recovery system, a kiln head heat recovery system, a calcination system, and a flue gas treatment system to solve the drying safety issues, flue gas treatment, and emission problems caused by volatile petroleum hydrocarbon components in the ceramsite pellets, thereby improving system thermal efficiency and reducing system energy consumption.

Description

Technical Field

[0001] This invention relates to the field of oil sludge ceramsite production technology, and in particular to a production process and system for preparing high-performance lightweight aggregates using fallen oil sludge and pyrolysis slag. Background Technology

[0002] Oil sludge is a large amount of hazardous solid waste such as oil sludge and oil sands generated when fine particles from oil reservoirs seep into the surface system along with produced fluids from different oils during the extraction, transportation, refining, and storage of crude oil or during oil accidents. Hazards: The microorganisms, heavy metals, inorganic salts, benzene compounds, phenols, petroleum hydrocarbons, and other organic pollutants in oil sludge not only pollute the surrounding soil and water bodies but also emit a certain amount of foul-smelling gases. Based on different generation pathways, oil sludge can be roughly divided into the following three categories: (1) oil sludge produced during crude oil extraction; (2) oil sludge from the bottom of tanks produced during crude oil gathering and transportation; and (3) oil sludge generated during the treatment of oily wastewater in refineries. The total amount of newly added oil sludge in China each year is about 6 million tons, of which oilfield oil sludge and refinery oil sludge each account for 3 million tons. In addition, there is a large amount of existing oil sludge formed by historical backlog. Currently, there are numerous oil sludge treatment technologies available in China, but they generally suffer from limited applicability and high treatment costs. As a result, a significant proportion of newly generated oil sludge each year remains untreated, leading to widespread illegal landfilling and substandard discharge. Direct discharge of untreated oil sludge not only wastes resources but also severely impacts land, human health, surface vegetation, and surface and groundwater. Therefore, effective oil sludge disposal has become a pressing technological bottleneck that urgently needs to be addressed.

[0003] Pyrolysis residue is a hazardous waste primarily composed of inorganic matter, generated during the pyrolysis of oily sludge. Oily sludge pyrolysis technology refers to a method of treating sludge by breaking down and thermally shrinking organic matter and oils in oily sludge under anaerobic, high-temperature conditions. With the aid of a catalyst, distillation and thermal decomposition are integrated, transforming the sludge into a harmless treatment process containing solid, liquid, and gaseous phases. This method decomposes oily sludge into inorganic mineral residues, oils, and petroleum hydrocarbons through pyrolysis. While the oils and petroleum hydrocarbons can be sold as products and generate economic benefits, the pyrolysis residue is still classified as hazardous waste. Since landfilling of pyrolysis residue has been prohibited by relevant national departments, there is currently no effective way to utilize it, and this issue urgently needs to be addressed.

[0004] Fly ash is a byproduct of the combustion of finely ground coal in boilers of coal-fired power plants. Fly ash is generally grayish-brown, usually acidic, and has a specific surface area of ​​250–500 m². 2Fly ash, weighing approximately 1 kg, ranges in size from several hundred micrometers to a few micrometers, typically in spherical particles. Its main chemical components are SiO2, Al2O3, and Fe2O3, sometimes also containing high levels of CaO. Fly ash is a typical heterogeneous material containing unburned carbon and unaltered minerals such as quartz. my country's annual fly ash production and accumulated stockpiles have been increasing year by year. Differences in resource abundance, economic strength, and infrastructure scale across different regions of the country have led to significant regional variations in fly ash production, stockpiles, and comprehensive utilization. In particular, Shanxi, Inner Mongolia, and Shaanxi provinces have large fly ash production and stockpiles but low comprehensive utilization rates, urgently requiring the search for suitable resource-based and high-value-added utilization methods.

[0005] When preparing ceramsite from solid waste and hazardous waste, to increase the output of the rotary kiln, the granulated raw ceramsite pellets need to be dried at 100-300℃ before calcination, and only one conventional rotary drying equipment is used. The drying process generates a certain amount of volatile organic compounds (VOCs) and flammable and explosive volatile substances such as petroleum hydrocarbons. Existing technologies, such as Chinese Patent Publication No. CN114370759A, disclose a low-energy system and process for preparing ceramsite from solid waste. However, these flammable and explosive volatile organic compounds are difficult to remove through flue gas treatment methods such as desulfurization, denitrification, and dust removal, requiring further combustion in a secondary combustion chamber for complete combustion, resulting in a large flue gas treatment volume and high energy consumption.

[0006] Chinese patent publication CN109553390A discloses a sludge ceramsite production system. The sludge is first dried, then pulverized into sludge powder, mixed with different raw materials, and subjected to ball milling and stirring processes. Afterward, it is granulated to form ceramsite pellets, calcined, and finally screened to obtain the final product. This patent directly dries the sludge before using it to prepare ceramsite pellets. Because sludge drying releases a large amount of odor and volatile organic compounds, it generates a significant amount of volatile waste gas, which complicates the exhaust gas treatment system, requiring a large environmental treatment capacity, significantly increasing environmental treatment costs, and reducing the economic value of the sludge ceramsite.

[0007] Chinese patent CN115682635A discloses a drying process and system suitable for materials containing high levels of volatile organic compounds (VOCs). This patent proposes a two-stage drying technology to address the drying problem of materials containing high VOCs. Raw material pellets are first fed into a first-stage indirect dryer and dried indirectly to a moisture content of 10%, then fed into a second-stage direct dryer and dried directly to a moisture content of <2%, before being sent to a rotary kiln for calcination. In order to ensure that most of the highly volatile VOCs are volatilized in the first-stage indirect drying, the moisture content in the first stage is dried from 22-23% to 10%, with the remainder dried to 2% in the second stage. However, this patent does not consider the matching of the drying capacities of the two stages, resulting in increased drying energy consumption. In particular, when the drying capacity of the first stage is insufficient, there are no measures to supplement the heat source, thus affecting the drying capacity of the second stage.

[0008] In summary, the existing technology has at least the following technical problems:

[0009] (1) Existing technologies for the pretreatment of oily sludge cannot guarantee that it meets the requirements of efficient homogenization with powdery solid wastes such as fly ash, which leads to uneven distribution of oily substances inside the raw material balls after granulation, and ultimately increases the breakage rate during drying and firing.

[0010] (2) When using general solid waste and oily hazardous waste as raw materials to prepare ceramsite, the flue gas from the rotary kiln and dryer contains a large amount of volatile organic compounds. During the drying process, volatile organic compounds and petroleum hydrocarbons may be flammable and explosive when they encounter oxygen-containing gases. However, there are currently no protective measures in the existing technology to prevent volatile organic compounds from causing deflagration.

[0011] (3) In the production of oil sludge ceramsite, the direct drying method is used, which generates a large amount of drying waste gas and also produces high concentrations of VOCs. These are difficult to treat by conventional tail gas treatment methods. Generally, a secondary combustion chamber is required for combustion treatment. However, since the secondary combustion chamber needs to be maintained at above 850°C to burn off the VOCs, the energy consumption of the secondary combustion chamber is relatively high when the flue gas treatment volume is relatively large.

[0012] (4) When the VOC volatilization temperature in the ceramsite is higher than 300℃, increasing the drying temperature will cause the ceramsite raw material balls to break. This is because the ceramsite raw material balls containing moisture will release moisture rapidly due to the influence of higher temperature during drying, causing the ceramsite to crack.

[0013] (5) Currently, a single-stage dryer is used in the drying system. As the moisture content of the ceramsite raw pellets decreases, the breakage rate increases significantly, the product yield decreases, the amount of dust in the flue gas increases sharply, flying sand is generated in the kiln, and the cost of the dust collection system increases. When the moisture content of the ceramsite raw pellets is not matched in the two-stage drying system, it will also cause an increase in the breakage rate and drying energy consumption during the drying process.

[0014] (6) In the technology of utilizing waste heat at the kiln tail, the commonly used air-to-air heat exchange efficiency is relatively low and the heat exchange time is long. It is impossible to reduce the temperature of the kiln tail flue gas from 850℃ to 350℃ in order to avoid the regeneration of dioxins.

[0015] (7) The existing firing equipment has not been optimized and upgraded specifically for the characteristics of oily clay ceramsite, resulting in high energy consumption, high product breakage rate and unfavorable high-efficiency denitrification at high temperature at the kiln tail, which in turn leads to increased denitrification costs in subsequent flue gas treatment.

[0016] In summary, neither general solid waste nor hazardous solid waste can be used alone to generate significant economic value, resulting in a massive historical accumulation of both types of waste and causing serious environmental impact. Therefore, finding a method to combine general solid waste and hazardous waste for utilization that generates high economic value without producing secondary pollutants is the best approach to disposing of these wastes. Summary of the Invention

[0017] This invention addresses the problems of existing technologies by providing a production process and system for preparing high-performance lightweight aggregates using landfill sludge and pyrolysis slag. The system comprises the following components: a sludge pretreatment system, a sludge ceramsite granulation system, a kiln tail heat recovery system, a kiln head heat recovery system, a calcination system, and a tail gas treatment system. While utilizing hazardous waste sludge and general solid waste in the combined batching of high-performance ceramsite, this invention overcomes the complexity of sludge raw material components by proposing an efficient sludge pretreatment and mixing system, ensuring the uniformity and stability of the raw material composition. It fully utilizes the waste heat in the calcination system for drying the raw material pellets, improving system thermal efficiency and reducing system energy consumption and raw material pellet breakage rate. In particular, by employing a unique drying process and tail gas treatment system specifically for sludge ceramsite, it solves the problem of flue gas treatment caused by volatile components and petroleum hydrocarbons in the raw ceramsite pellets, achieving ultra-low emissions of sludge ceramsite flue gas. This realizes low-carbon and green production of ceramsite using solid waste and hazardous waste sludge through calcination, which has significant practical implications.

[0018] This invention is implemented as follows: a production process for preparing high-performance lightweight aggregate using landfill sludge and pyrolysis residue includes the following steps:

[0019] After the raw materials of oily sludge and / or pyrolysis residue, fly ash and bentonite powder are measured according to the proportion, they are fed into two twin-shaft mixers connected in series for mixing and staged water addition. The ceramsite raw material from the twin-shaft mixer is sent to the oily sludge ceramsite granulation system for extrusion granulation, and then sent to the shaping machine for shaping to obtain ceramsite raw material balls.

[0020] The raw ceramsite pellets from the oil mud ceramsite granulation system are first sent to a rotary indirect dryer for indirect drying to a moisture content of 12-17%, and then sent to a belt dryer for further drying to a moisture content of ≤4%. After that, the raw ceramsite pellets are sent to a ceramsite rotary kiln for high-temperature calcination. The calcined pellets are cooled by a grate cooler and then screened and stored. After cooling, the oil mud ceramsite product with a bulk density of 800-1100 kg / m3, a cylinder compressive strength of 10-23 MPa, and a 1-hour water absorption rate of 2.14-9.8% is obtained.

[0021] Preferably, the raw materials, by weight percentage, consist of 5-50% oily sludge and / or 5-50% pyrolysis residue, 40-70% fly ash, and 5-15% bentonite; the sum of the weight percentages of the oily sludge and / or pyrolysis residue, fly ash, and bentonite is 100%.

[0022] Preferably, the fallen oil sludge is screened by a loader with a screening function to remove stones and other debris larger than 20mm. Then the loader sends the screened fallen oil sludge to a crusher for crushing and dispersing. The crushed fallen oil sludge is then sent to a drum screen for screening. The fallen oil sludge ≤5mm enters the batching bin of the batching system for later use, while the material >5mm enters the crusher again for processing.

[0023] The pyrolysis residue is the pyrolysis residue produced from the pyrolysis of oil sludge.

[0024] Preferably, the moisture content of the ceramsite raw material after water is added in stages to the first twin-shaft mixer is controlled at 8-15%, and the moisture content of the ceramsite raw material after water is added in stages to the second twin-shaft mixer is controlled at 18-25%.

[0025] Preferably, when granulating the ceramsite raw material, the particle size is controlled between 5-15mm; during shaping, the sphericity is controlled to be ≤2.0.

[0026] Preferably, the drying medium of the rotary indirect dryer is heat transfer oil, and the drying heat source comes from the kiln tail flue gas of the ceramsite rotary kiln. After SNCR denitrification in the kiln, the 700-900℃ kiln tail flue gas is dusted and then indirectly heat-exchanged through the heat transfer oil heat exchanger, and the temperature is reduced to 300℃~350℃ before entering the flue gas treatment system for treatment and discharge in compliance with standards. The temperature of the heat transfer oil rises to 200-350℃, and the heat transfer oil carries the residual heat from the kiln tail into the rotary indirect dryer to dry the ceramsite raw material balls. The heat transfer oil coming out of the rotary indirect dryer is recycled back to the heat transfer oil heat exchanger to replenish the heat source.

[0027] In a further preferred embodiment, the flue gas in the flue gas treatment system, after heat exchange at 300℃~350℃, is first rapidly cooled to 190~200℃, while simultaneously controlling the residence time of the flue gas in the 200℃~350℃ temperature range to be less than 1 second; then, the rapidly cooled flue gas at 190~200℃ undergoes dioxin removal and acid gas removal, followed by dust removal to remove particulate matter from the flue gas, ensuring that the particulate matter concentration in the flue gas does not exceed 20 mg / m³. 3 The dust-removed flue gas then enters a two-stage wet deacidification system. First, liquid atomization is used to enhance gas-liquid contact and mass transfer. Then, acid-base neutralization reaction is used to eliminate acidic substances in the flue gas. The deacidified flue gas is then introduced into the chimney by an induced draft fan to meet emission standards.

[0028] Preferably, the drying exhaust gas containing high concentrations of petroleum hydrocarbons and water vapor generated during the drying of the ceramsite raw pellets in the rotary indirect dryer is sequentially subjected to dust removal and condensation. The condensate generated during condensation is sent to a water treatment system. A portion of the water in the water treatment system is used in the oil sludge ceramsite granulation system. The petroleum hydrocarbon-containing exhaust gas after condensation and dehydration is sent to the high-temperature section of the grate cooler and used as secondary combustion air in the ceramsite rotary kiln to burn off the petroleum hydrocarbons it contains.

[0029] Preferably, the drying heat source of the belt dryer is hot air at 250-300°C from the grate cooler after dust removal and / or circulating air heated by a natural gas hot air furnace.

[0030] Preferably, a portion of the drying exhaust gas containing low concentrations of petroleum hydrocarbons and water vapor generated during the drying of ceramsite raw pellets in the belt dryer enters the hot air furnace as combustion air to burn off the petroleum hydrocarbons. The remaining portion is successively sent to the grate cooler after dust removal and condensation. A portion of the gas is blown into the high-temperature section of the grate cooler as combustion air to enter the ceramsite rotary kiln to burn off the petroleum hydrocarbons, while the other portion is blown into the low-temperature section of the grate cooler as a cooling air source to cool the high-temperature ceramsite in the grate cooler and obtain heat before re-entering the belt dryer to dry the ceramsite raw pellets, thus realizing the recycling of exhaust gas. The condensed wastewater enters the water treatment system for treatment and is discharged after meeting the standards.

[0031] Preferably, the drying temperature and drying efficiency of the rotary indirect dryer and the belt dryer are adjusted according to the concentration of volatile petroleum hydrocarbons in the raw material pellets, the volatile temperature range, and the plasticity of the ceramsite raw material pellets, and the air intake ratio in the grate cooler is automatically adjusted.

[0032] Preferably, the rotary kiln for ceramsite is a rotary kiln for ceramsite calcination, comprising a kiln body. The inner wall of the kiln body is provided with a refractory layer. From the kiln tail to the kiln head, the kiln body consists of a material-blocking check zone and a rapid calcination zone. The material-blocking check zone has a material inlet narrowing on the inlet side and a material-blocking protrusion in the middle. A high-temperature SNCR denitrification device is provided at the center of the material inlet end of the material-blocking check zone. The inner wall of the kiln body in the rapid combustion zone has three or more arched sections with curved structures along the circumference of the kiln body. The outlet side of the rapid calcination zone has a discharge narrowing.

[0033] More preferably, both the inlet and outlet constrictions are provided with guide slopes to the inner side of their respective areas, the height of the baffle boss is not greater than 1 / 2 of the height of the arch, and the inlet end of the arch is provided with a guide platform.

[0034] A production system for preparing high-performance lightweight aggregates using fallen oil sludge and pyrolysis slag comprises the following parts: an oil sludge pretreatment system, an oil sludge ceramsite granulation system, a rotary indirect dryer, a belt dryer, a kiln tail heat recovery system, a kiln head heat recovery system, a firing system, and a flue gas treatment system; the firing system includes a ceramsite rotary kiln and a grate cooler.

[0035] The oil sludge pretreatment system is used to pretreat the incoming oil sludge into fine particles of ≤5mm. The oil sludge ceramsite granulation system is used to mix and granulate the pretreated oil sludge, pyrolysis slag, fly ash, and bentonite powders. The material outlet of the oil sludge ceramsite granulation system is connected to the material inlet of the rotary indirect dryer. The material outlet of the rotary indirect dryer is connected to the material inlet of the belt dryer. The material outlet of the belt dryer is connected to the kiln tail of the ceramsite rotary kiln.

[0036] The rotary kiln for ceramsite is equipped with a high-temperature SNCR denitrification device inside the kiln tail. The flue gas outlet of the rotary kiln for ceramsite is connected to the gas inlet of the first dust collector. The gas outlet of the first dust collector is connected to the gas inlet of the thermal oil heat exchanger. The gas outlet of the thermal oil heat exchanger is connected to the flue gas treatment system. The thermal oil outlet of the thermal oil heat exchanger is connected to the drying medium inlet of the rotary indirect dryer. The drying medium outlet of the rotary indirect dryer is connected to the thermal oil inlet of the thermal oil heat exchanger.

[0037] The tertiary air outlet of the grate cooler is connected to the gas inlet of the second dust collector, and the gas outlet of the second dust collector is connected to the drying medium inlet of the belt dryer.

[0038] The exhaust gas outlet of the rotary indirect dryer is connected to the gas inlet of the third dust collector, the gas outlet of the third dust collector is connected to the gas inlet of the first condensation system, the gas outlet of the first condensation system is connected to the high-temperature section gas inlet of the grate cooler, the condensate outlet of the first condensation system is connected to the water treatment system, and the outlet of the water treatment system is connected to the inlet of the oil sludge ceramsite granulation system.

[0039] The first drying exhaust gas outlet of the belt dryer is connected to the gas inlet of the fourth dust collector. The gas outlet of the fourth dust collector is connected to the gas inlet of the second condensation system. The gas outlet of the second condensation system is connected to the high-temperature section gas inlet and the medium-low temperature section gas inlet of the grate cooler, respectively. The condensate outlet of the second condensation system is connected to the water treatment system. The second drying exhaust gas outlet of the belt dryer is connected to the gas inlet of the hot air furnace. The gas outlet of the hot air furnace is connected to the gas inlet of the belt dryer.

[0040] Preferably, the flue gas treatment system includes a quench tower, a dry desulfurization tower, a bag filter, and a two-stage wet desulfurization tower. The gas outlet of the heat transfer oil heat exchanger is connected to the inlet of the quench tower, the gas outlet of the quench tower is connected to the gas inlet of the dry desulfurization tower, the gas outlet of the dry desulfurization tower is connected to the gas inlet of the bag filter, the gas outlet of the bag filter is connected to the gas inlet of the two-stage wet desulfurization tower, and the gas outlet of the two-stage wet desulfurization tower is connected to the gas inlet of the chimney.

[0041] Preferably, it also includes a natural gas hot air furnace, which is connected to the drying medium inlet of the belt dryer.

[0042] The advantages and positive effects of this invention are:

[0043] This invention utilizes pretreated hazardous oil sludge and general solid waste as raw materials to prepare ceramsite, while fully leveraging the waste heat from the calcination system for pellet drying, thus improving system thermal efficiency and reducing energy consumption. In particular, the combined process technology of the kiln tail heat recovery system, kiln head heat recovery system, calcination system, and flue gas treatment system solves the drying safety, flue gas treatment, and emission problems caused by volatile petroleum hydrocarbon components in the ceramsite raw pellets. This invention achieves low-carbon and green production of ceramsite using general solid waste and hazardous oil sludge through calcination, which has significant practical implications. Attached Figure Description

[0044] Figure 1 This is a flowchart of a production system for preparing high-performance lightweight aggregates using landed sludge and pyrolysis residue, provided in an embodiment of the present invention.

[0045] Figure 2This is a schematic diagram of the structure of the rotary kiln for ceramsite provided in an embodiment of the present invention;

[0046] Figure 3 yes Figure 2 AA section view;

[0047] Figure 4 yes Figure 2 BB cross-sectional view.

[0048] In the diagram: 1. Kiln body; 101. Material blocking check zone; 1011. Material blocking boss; 1012. Feed inlet narrowing; 102. Rapid roasting zone; 1021. Arch height; 1022. Discharge narrowing; 2. Guide slope; 3. Guide platform; 4. Refractory layer. Detailed Implementation

[0049] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0050] In the description of this invention, it should be understood that the terms "upper", "lower", "front", "rear", "left", "right", "inner", "outer", etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. They are only for the convenience of describing this 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, they should not be construed as limitations on this invention.

[0051] In the description of this invention, it should be noted that, unless otherwise explicitly specified and limited, the terms "installation," "connection," and "linking" should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral connection; they can refer to a mechanical connection or an electrical connection; they can refer to a direct connection or an indirect connection through an intermediate medium; and they can refer to the internal connection of two components. Those skilled in the art can understand the specific meaning of the above terms in this invention based on the specific circumstances.

[0052] Please see Figure 1 The present invention provides a production process for preparing high-performance lightweight aggregate using landfill sludge and pyrolysis residue, comprising the following steps:

[0053] The raw materials in the batching system, namely, the fallen oil sludge, pyrolysis slag, fly ash, and bentonite powder, are accurately measured according to the batching ratio; by weight percentage, the fallen oil sludge is 5-50%, the pyrolysis slag is 5-50%, the fly ash is 40-70%, and the bentonite is 5-15%; the sum of the weight percentages of the fallen oil sludge, pyrolysis slag, fly ash, and bentonite is 100%.

[0054] Specifically, after the oil sludge arrives at the plant, it is stored in a stockpile and screened using a loader equipped with a screening function to remove stones and other debris larger than 20mm. The loader then feeds the screened oil sludge into a crusher for further crushing and dispersing. The crushed oil sludge is then sent to a drum screen for further screening. Oil sludge ≤5mm is sent to the batching system's batching hopper for later use, while material >5mm is sent back to the crusher for further processing. During the drum screen process, a vibrator is activated every 3-5 minutes to clear any clogging of the screen holes.

[0055] To address the characteristics of spilled oily sludge, a two-stage screening and one-stage crushing and dispersing system was designed, effectively solving the homogeneity problem of spilled oily sludge and preventing clogging caused by high oil content in some spilled oily sludge. The two-stage screening process removes coarser sand and gravel particles from the spilled sludge, effectively reducing their abrasion and failure rate on subsequent granulation and mixing equipment. A drum screen is used to remove particles larger than 5mm, ensuring the homogeneity of the raw material. A vibrator prevents clogging of the drum screen, ensuring the continuity of the pretreatment process. This oily sludge pretreatment technology solves the problems of secondary pollution from existing pretreatment technologies and increased pyrolysis slag caused by conditioning agents in the pyrolysis section. It achieves efficient pretreatment of spilled oily sludge, allowing high-oil-content spilled oily sludge to be pretreated and then fed into the pyrolysis process for higher economic benefits, while low-oil-content spilled oily sludge is pretreated and then fed into the ceramsite firing process to produce ceramsite. This not only yields high-performance green building materials but also fundamentally eliminates hazardous waste oily sludge and achieves high-value utilization of spilled oily sludge, which has significant practical implications. Oily sludge can also be replaced with coal gangue, sludge, and contaminated soil containing volatile substances.

[0056] Pyrolysis residue is a solid waste produced from the hot washing process of oily sludge. Part of it is transported to the raw material workshop by a forklift for storage, and part of it is stored in the batching silo of the batching system for later use.

[0057] Fly ash can also be replaced by gasification slag, waste soil, shale, silt and other silica-alumina raw materials.

[0058] The proportioned raw materials are then sequentially fed into two twin-shaft mixers connected in series for mixing and staged water addition. Water is added in stages until the moisture content of the ceramsite raw material exiting the first twin-shaft mixer is controlled at 8-15%, and in stages until the moisture content of the ceramsite raw material exiting the second twin-shaft mixer is controlled at 18-25%. The ceramsite raw material exiting the twin-shaft mixers is then fed into the extrusion granulator of the oil-sludge ceramsite granulation system for extrusion granulation, with the particle size controlled at 5-15mm. It is then fed into a shaping machine for shaping, controlling the sphericity to ≤2.0, to obtain ceramsite raw material balls.

[0059] A two-stage mixing and segmented water addition scheme using a series-connected twin-shaft mixer is proposed. Targeting the characteristics of viscous and wet materials, the moisture content at which plasticity or viscosity increases instantaneously is measured. The water addition process is divided into multiple stages. The mixing speed is increased before a sudden change in viscosity, improving the uniformity of the mixed material. This solves the problem of high viscosity and plasticity in the initial stage after a single water addition of multi-component dry powder materials, making it difficult to mix evenly and continue conveying. It achieves a slow emergence of plasticity during the mixing of viscous and wet materials, ensuring the uniformity and controllable moisture content of the raw material after mixing. This is beneficial to the stability of the subsequent granulation process and avoids problems such as material blockage and poor mixing uniformity caused by early plasticity. It can be used for mixing materials such as sludge, oil sludge, and fly ash, and for controlling the moisture content of raw materials, and has significant practical implications.

[0060] The ceramsite raw pellets from the ceramsite granulation system are first fed into a rotary indirect dryer for indirect drying to a moisture content of 12-17%. The drying medium in the rotary indirect dryer is heat transfer oil, and the drying heat source comes from the kiln tail flue gas of the ceramsite rotary kiln. After SNCR denitrification in the kiln, the 700-900℃ kiln tail flue gas is dusted and then indirectly cooled by heat transfer oil heat exchanger to a temperature of 300℃-350℃ before entering the flue gas treatment system for treatment to meet emission standards. The heat transfer oil temperature rises to 200-350℃, and the heat transfer oil carries the residual heat from the kiln tail into the rotary indirect dryer to dry the ceramsite raw pellets. The heat transfer oil from the rotary indirect dryer is then recycled back to the heat transfer oil heat exchanger to replenish the heat source. The drying exhaust gas containing high concentrations of petroleum hydrocarbons and water vapor generated during the drying of the ceramsite raw pellets in the rotary indirect dryer is successively subjected to dust removal and condensation. The condensate produced by condensation is sent to the water treatment system. A portion of the water in the water treatment system is used in the oil sludge ceramsite granulation system. The petroleum hydrocarbon-containing exhaust gas after condensation and dehydration is sent to the high-temperature section of the grate cooler and used as secondary combustion air in the ceramsite rotary kiln to burn off the petroleum hydrocarbons it contains.

[0061] An energy-saving process and system comprised of a thermal oil heat exchanger, an indirect dryer, and a condensation system solves the problems of flue gas treatment for special materials containing high levels of volatile organic compounds (VOCs) or petroleum hydrocarbons, as well as the risk of deflagration when these components encounter oxygen-containing gases during the direct drying stage. The thermal oil heat exchanger can rapidly reduce the temperature of the kiln tail flue gas to 200-350℃, and its operating temperature range can be adjusted according to the characteristics of the material being dried, facilitating ultra-low emissions. The condensation system reduces the moisture content in the drying exhaust gas, and the treated condensate achieves water conservation. The kiln tail waste heat recovery system fully utilizes the waste heat from the firing system for combustion assistance and material drying, improving system thermal efficiency and reducing energy consumption. This highly efficient recovery and utilization of waste heat from the firing system allows for the drying of sludge, oil sludge, coal gangue, and other materials containing high concentrations of VOCs or petroleum hydrocarbons, exhibiting energy-saving, low-carbon, and green production characteristics, and possessing significant practical value.

[0062] In the flue gas treatment system, the flue gas, after heat exchange at 300℃~350℃, is first rapidly cooled to 190~200℃, while simultaneously controlling the residence time of the flue gas in the 200℃~350℃ temperature range to be less than 1 second. Then, the rapidly cooled flue gas at 190~200℃ undergoes dioxin removal and acid gas removal. Finally, the reacted flue gas is subjected to dust removal to remove particulate matter, ensuring that the particulate matter concentration in the flue gas does not exceed 20 mg / m³. 3 The dust-removed flue gas then enters a two-stage wet deacidification system. First, liquid atomization is used to enhance gas-liquid contact and mass transfer. Then, acid-base neutralization reaction is used to eliminate acidic substances in the flue gas. The deacidified flue gas is then introduced into the chimney by an induced draft fan to meet emission standards.

[0063] By fully utilizing flue gas quenching, dioxin removal, and multi-stage deacidification processes, the problem of NO content in flue gas was solved. X The system addresses the flue gas treatment issues caused by dioxins and acidic gases, ultimately meeting the GB18484-2020 emission standards. After waste heat recovery, the flue gas temperature drops to approximately 350℃. Flue gas at this temperature can be treated using a flue gas quenching system, reducing the investment cost of the quenching section. After quenching, the flue gas undergoes dioxin removal and multi-stage acid removal processes, resolving the flue gas treatment problems caused by dioxins and acidic gases. A three-stage acid removal process is employed, with the first stage using a dry or semi-dry method, and the latter two stages using wet methods, effectively removing acidic gases from the flue gas.

[0064] The ceramsite, after being dried in a rotary indirect dryer, is then fed into a belt dryer for further drying until the moisture content is ≤4%. The heat source for the belt dryer is 250-300℃ hot air from the grate cooler after dust removal and / or circulating air heated by a natural gas hot air furnace. A portion of the drying exhaust gas containing low concentrations of petroleum hydrocarbons and water vapor generated during the drying of the ceramsite raw pellets in the belt dryer enters the hot air furnace as combustion air to burn off the petroleum hydrocarbons. The remaining portion, after being successively dusted and condensed, is sent to the grate cooler. Part of this gas is blown into the high-temperature section of the grate cooler as combustion air to burn off the petroleum hydrocarbons in the ceramsite rotary kiln. The other part is blown into the low-temperature section of the grate cooler as a cooling air source to cool the high-temperature ceramsite in the grate cooler, and then re-enters the belt dryer to dry the ceramsite raw pellets, thus achieving waste gas recycling.

[0065] By fully utilizing the waste heat in the calcination system for combustion assistance and pellet drying, the system's thermal efficiency is improved and energy consumption is reduced. In particular, the waste gas recycling scheme between the grate cooler and the belt dryer eliminates the need for a high-energy-consuming secondary combustion chamber, solving the problem of high energy consumption and excessive VOC emissions caused by VOC components generated during the drying process entering the flue gas treatment system. This achieves recycling and reuse, reaching the goal of ultra-low emissions and energy conservation during the drying process of VOC-containing materials or ceramsite. This method enables the preparation of oil sludge ceramsite using solid waste and hazardous waste through calcination, achieving energy-saving, low-carbon, and green production, which has significant practical implications.

[0066] The drying temperature and drying efficiency of the rotary indirect dryer and belt dryer are adjusted according to the concentration of volatile petroleum hydrocarbons in the raw material pellets, the range of volatilization temperature, and the plasticity of the ceramsite raw material pellets, and the air intake ratio in the grate cooler is automatically adjusted.

[0067] After being dried by a belt dryer, the raw ceramsite pellets are fed into a rotary kiln for high-temperature calcination. The calcined pellets are then cooled by a grate cooler, screened, and stored. After cooling, oily mud ceramsite products with a bulk density of 800-1100 kg / m3, a cylinder compressive strength of 10-23 MPa, and a 1-hour water absorption rate of 2.14-9.8% are obtained.

[0068] The rotary kiln for calcining ceramsite includes a kiln body 1. The inner wall of the kiln body 1 is provided with a refractory layer 4. From the kiln tail to the kiln head, the kiln body 1 consists of a material-blocking check zone 101 and a rapid calcination zone 102. The material-blocking check zone 101 has a material inlet constriction 1012 on its inlet side and a material-blocking boss 1011 in the middle. A high-temperature SNCR denitrification device is located at the center of the material inlet end of the material-blocking check zone. The inner wall of the rapid calcination zone 102 has three or more arched sections 1021 with curved surfaces along the circumference of the kiln body. The outlet side of the rapid calcination zone has an outlet constriction 1022. Both the inlet constriction 1012 and the outlet constriction 1022 have guide slopes 2 extending inwards to their respective zones. The height of the material-blocking boss 1011 is no greater than half the height of the arched section 1021. A guide platform 3 is located at the inlet end of the arched section 1021.

[0069] The backflow prevention zone prevents material backflow and extends the residence time of the material in the kiln tail. This results in slower heating of the same material per unit time, preventing the ceramsite from directly rushing to the kiln head, thus ensuring the required firing time for the ceramsite blanks and guaranteeing their quality. The feed constriction reduces ceramsite breakage. The rapid firing zone primarily achieves rapid heat exchange in the thermoplastic state, rapid firing of the ceramsite, and vitrification of the ceramsite surface. Upon entering the rapid firing zone, the high temperature from the torch flame causes a rapid formation of a slightly molten liquid phase on the ceramsite surface, trapping the internal gas. This gas undergoes a uniform expansion, causing the ceramsite to expand instantaneously or slightly. After cooling, the ceramsite surface becomes vitrified, which helps reduce water absorption and increase surface strength. The interior forms a homogeneous porous structure, reducing the bulk density of the ceramsite. The discharge constriction collects the ceramsite. The guide slopes at the feed and discharge constrictions prevent breakage during ceramsite transport and also serve as flow guides.

[0070] The rotary kiln for ceramsite calcination, through the design of an additional check zone for ceramsite material retention, prevents backflow while simultaneously enabling the orderly release of volatile substances within the ceramsite. This results in ceramsite with varying pore structures and bulk densities, while also reducing breakage rates. The design of a rapid calcination zone improves heat exchange efficiency and filling rate, as well as enhances the erosion resistance of the refractory material. Rapid calcination in this zone increases the liquid phase content on the ceramsite surface, improving its vitrification, reducing water absorption, and increasing surface strength. Overall, the design of the rotary kiln for ceramsite calcination achieves efficient and rapid production of ceramsite, increasing productivity and possessing high application and promotional value, with broad market prospects in the ceramics production field.

[0071] Cement clinker tends to form large lumps due to its liquid phase, while ceramsite has very little liquid phase after sintering and virtually no agglomeration. Therefore, the crushing device at the discharge port of the grate cooler is eliminated. Because the bulk density of ceramsite is lower than that of cement clinker, its porosity increases in the grate bed, enhancing the penetration of cooling air and reducing the required cooling air pressure, thus saving electricity. This allows for an increase in the material accumulation height (or grate bed height) within the grate cooler, significantly improving the unit cooling capacity, increasing waste heat recovery efficiency, and reducing cooling power consumption.

[0072] The production system for preparing high-performance lightweight aggregates using fallen oil sludge and pyrolysis slag to achieve the above-mentioned process consists of the following parts: oil sludge pretreatment system, oil sludge ceramsite granulation system, rotary indirect dryer, belt dryer, natural gas hot blast stove, kiln tail heat recovery system, kiln head heat recovery system, calcination system, and flue gas treatment system; the calcination system includes a ceramsite rotary kiln and a grate cooler.

[0073] The oil sludge pretreatment system is used to pretreat the incoming oil sludge into fine particles ≤5mm. The oil sludge ceramsite granulation system is used to mix and granulate the pretreated oil sludge, pyrolysis slag, fly ash, and bentonite powders. The material outlet of the oil sludge ceramsite granulation system is connected to the material inlet of the rotary indirect dryer. The material outlet of the rotary indirect dryer is connected to the material inlet of the belt dryer. The material outlet of the belt dryer is connected to the kiln tail of the ceramsite rotary kiln.

[0074] The rotary kiln tail of the ceramsite is equipped with a high-temperature SNCR denitrification device. The flue gas outlet of the rotary kiln tail is connected to the gas inlet of the first dust collector. The gas outlet of the first dust collector is connected to the gas inlet of the thermal oil heat exchanger. The gas outlet of the thermal oil heat exchanger is connected to the flue gas treatment system. The thermal oil outlet of the thermal oil heat exchanger is connected to the drying medium inlet of the rotary indirect dryer. The drying medium outlet of the rotary indirect dryer is connected to the thermal oil inlet of the thermal oil heat exchanger.

[0075] The tertiary air outlet of the grate cooler is connected to the gas inlet of the second dust collector, and the gas outlet of the second dust collector is connected to the drying medium inlet of the belt dryer; the natural gas hot air furnace is connected to the drying medium inlet of the belt dryer.

[0076] The exhaust gas outlet of the rotary indirect dryer is connected to the gas inlet of the third dust collector. The gas outlet of the third dust collector is connected to the gas inlet of the first condensation system. The gas outlet of the first condensation system is connected to the high-temperature section gas inlet of the grate cooler. The condensate outlet of the first condensation system is connected to the water treatment system. The outlet of the water treatment system is connected to the inlet of the twin-shaft mixer of the oil sludge ceramsite granulation system. The exhaust gas outlet of the belt dryer is connected to the gas inlet of the fourth dust collector. The gas outlet of the fourth dust collector is connected to the gas inlet of the second condensation system. The gas outlet of the second condensation system is connected to the high-temperature section gas inlet and the medium-low temperature section gas inlet of the grate cooler, respectively. The condensate outlet of the second condensation system is connected to the water treatment system. The exhaust gas outlet of the belt dryer is connected to the gas inlet of the hot air furnace. The gas outlet of the hot air furnace is connected to the gas inlet of the belt dryer.

[0077] The flue gas treatment system includes a quench tower, a dry desulfurization tower, a bag filter, and a two-stage wet desulfurization tower. The gas outlet of the heat transfer oil heat exchanger is connected to the inlet of the quench tower, the gas outlet of the quench tower is connected to the gas inlet of the dry desulfurization tower, the gas outlet of the dry desulfurization tower is connected to the gas inlet of the bag filter, the gas outlet of the bag filter is connected to the gas inlet of the two-stage wet desulfurization tower, and the gas outlet of the two-stage wet desulfurization tower is connected to the gas inlet of the chimney.

[0078] In summary, this invention utilizes pretreated hazardous oil sludge and general solid waste as raw materials to prepare ceramsite, while fully leveraging the waste heat in the calcination system for pellet drying, thereby improving system thermal efficiency and reducing energy consumption. In particular, the combined process technology of the kiln tail heat recovery system, kiln head heat recovery system, calcination system, and flue gas treatment system solves the drying safety issues, flue gas treatment, and emission problems caused by volatile petroleum hydrocarbon components in the ceramsite raw pellets. This invention achieves low-carbon and green production of ceramsite using general solid waste and hazardous oil sludge through calcination, which has significant practical implications.

[0079] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, and are not intended 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 or all of the technical features therein. Such modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of the present invention.

Claims

1. A production process for preparing high-performance lightweight aggregate using landfill sludge and pyrolysis residue, characterized in that, Includes the following steps: The raw materials, including oily sludge and / or pyrolysis residue, fly ash, and bentonite powder, are measured according to the proportions and then fed into two twin-shaft mixers connected in series for mixing and staged water addition. The ceramsite raw material exiting the twin-shaft mixers is sent to the oily sludge ceramsite granulation system for extrusion granulation, and then sent to a shaping machine for shaping to obtain ceramsite raw material pellets. The ceramsite raw material pellets contain volatile petroleum hydrocarbons. The ceramsite raw pellets from the oil sludge granulation system are first fed into a rotary indirect dryer for indirect drying to a moisture content of 12-17%. The drying medium in the rotary indirect dryer is heat transfer oil, and the heat source is the flue gas from the kiln tail of the ceramsite rotary kiln. Then, they are further dried in a belt dryer until the moisture content is ≤4%, thus solving the drying safety issues caused by volatile petroleum hydrocarbon components in the ceramsite raw pellets. Afterward, the ceramsite raw pellets are fed into a ceramsite rotary kiln for high-temperature calcination. The calcined pellets are then cooled by a grate cooler, screened, and stored, achieving a bulk density of 800-1100 kg / m³. 3 Oily mud ceramsite products with a compressive strength of 10-23 MPa and a water absorption rate of 2.14-9.8% per hour; The rotary kiln for calcining ceramsite includes a kiln body with a refractory layer on its inner wall. From the kiln tail to the kiln head, the kiln body consists of a material-blocking check zone and a rapid calcining zone. The material-blocking check zone has a material inlet constriction on its inlet side and a material-blocking protrusion in the middle. A high-temperature SNCR denitrification device is located at the center of the material inlet end of the material-blocking check zone. The rapid calcining zone has three or more arched sections with curved structures along the circumference of the kiln body on its inner wall and a material outlet constriction on its outlet side. Both the material inlet constriction and the material outlet constriction have guide slopes leading to the inner side of their respective zones.

2. The production process for preparing high-performance lightweight aggregate using landfill sludge and pyrolysis residue according to claim 1, characterized in that: The raw materials, by weight percentage, consist of 5-50% oily sludge and / or 5-50% pyrolysis residue, 40-70% fly ash, and 5-15% bentonite; the sum of the weight percentages of the oily sludge and / or pyrolysis residue, fly ash, and bentonite is 100%.

3. The production process for preparing high-performance lightweight aggregate using landfill sludge and pyrolysis residue according to claim 1, characterized in that: The fallen oil sludge is screened by a loader with a screening function to remove stones and other debris larger than 20mm. Then the loader sends the screened oil sludge to a crusher for crushing and dispersing. After crushing, the oil sludge is sent to a drum screen for screening. Oil sludge ≤5mm enters the batching bin of the batching system for later use, while material >5mm enters the crusher again for processing. The pyrolysis residue is the pyrolysis residue produced from the pyrolysis of oil sludge.

4. The production process for preparing high-performance lightweight aggregate using landfill sludge and pyrolysis residue according to claim 1, characterized in that: When water is added in stages, the moisture content of the ceramsite raw material exiting the first twin-shaft mixer is controlled at 8-15%, and when water is added in stages, the moisture content of the ceramsite raw material exiting the second twin-shaft mixer is controlled at 18-25%.

5. The production process for preparing high-performance lightweight aggregate using landfill sludge and pyrolysis residue according to claim 1, characterized in that: When granulating raw ceramsite, the particle size should be controlled between 5-15mm; during shaping, the sphericity should be controlled to ≤2.

0.

6. The production process for preparing high-performance lightweight aggregate using landfill sludge and pyrolysis residue according to claim 1, characterized in that: After SNCR denitrification in the kiln, the 700-900℃ kiln tail flue gas is dusted and then indirectly heat-exchanged through a thermal oil heat exchanger, reducing its temperature to 300-350℃ before entering the flue gas treatment system for treatment and emission in compliance with standards. The thermal oil temperature rises to 200-350℃, and the thermal oil carries the residual heat from the kiln tail into a rotary indirect dryer to dry the ceramsite raw pellets. The thermal oil exiting the rotary indirect dryer is then recycled back to the thermal oil heat exchanger to replenish the heat source.

7. The production process for preparing high-performance lightweight aggregate using landfill sludge and pyrolysis residue according to claim 6, characterized in that: In the flue gas treatment system, the flue gas at 300-350℃ after heat exchange is first rapidly cooled to 190-200℃, while controlling the residence time of the flue gas in the 200℃-350℃ temperature range to be less than 1 second. The flue gas, after rapid cooling to 190-200℃, undergoes dioxin and acid gas removal. Following this, the flue gas is subjected to dust removal to remove particulate matter, ensuring the particulate matter concentration does not exceed 20 mg / m³. 3 The dust-removed flue gas then enters a two-stage wet deacidification system. First, liquid atomization is used to enhance gas-liquid contact and mass transfer. Then, acid-base neutralization reaction is used to eliminate acidic substances in the flue gas. The deacidified flue gas is then introduced into the chimney by an induced draft fan to meet emission standards.

8. The production process for preparing high-performance lightweight aggregate using landfill sludge and pyrolysis residue according to claim 1, characterized in that: A portion of the water in the water treatment system is used in the sludge ceramsite granulation system.

9. The production process for preparing high-performance lightweight aggregate using landfill sludge and pyrolysis residue according to claim 1, characterized in that: The drying heat source of the belt dryer is hot air at 250-300℃ from the grate cooler after dust removal and / or circulating air heated by a natural gas hot air furnace.

10. The production process for preparing high-performance lightweight aggregate using landfill sludge and pyrolysis residue according to claim 1, characterized in that: The drying exhaust gas containing low concentrations of petroleum hydrocarbons and water vapor generated during the drying of ceramsite raw pellets in the belt dryer is partially fed into a hot air furnace as combustion air to burn off the petroleum hydrocarbons. The remaining part is sent to a grate cooler after passing through dust removal and condensation. Part of the gas is blown into the high-temperature section of the grate cooler as combustion air to burn off the petroleum hydrocarbons in the ceramsite rotary kiln. The other part is blown into the low-temperature section of the grate cooler as a cooling air source to cool the high-temperature ceramsite in the grate cooler and obtain heat before re-entering the belt dryer to dry the ceramsite raw pellets, thus realizing the recycling of exhaust gas. The condensed wastewater is treated in a water treatment system and discharged after meeting the standards.

11. The production process for preparing high-performance lightweight aggregate using landfill sludge and pyrolysis residue according to claim 1, characterized in that: The height of the retaining protrusion is no greater than 1 / 2 of the height of the arch, and the material inlet end of the arch is provided with a guide platform.

12. A production system for preparing high-performance lightweight aggregate using landfill sludge and pyrolysis residue, implementing the production process of any one of claims 1-11, characterized in that: It consists of the following parts: oil sludge pretreatment system, oil sludge ceramsite granulation system, rotary indirect dryer, belt dryer, kiln tail heat recovery system, kiln head heat recovery system, firing system and flue gas treatment system; the firing system includes ceramsite rotary kiln and grate cooler. The oil sludge pretreatment system is used to pretreat the incoming oil sludge into fine particles of ≤5mm. The oil sludge ceramsite granulation system is used to mix and granulate the pretreated oil sludge, pyrolysis slag, fly ash, and bentonite powders. The material outlet of the oil sludge ceramsite granulation system is connected to the material inlet of the rotary indirect dryer. The material outlet of the rotary indirect dryer is connected to the material inlet of the belt dryer. The material outlet of the belt dryer is connected to the kiln tail of the ceramsite rotary kiln. The rotary kiln for ceramsite is equipped with a high-temperature SNCR denitrification device inside the kiln tail. The flue gas outlet of the rotary kiln for ceramsite is connected to the gas inlet of the first dust collector. The gas outlet of the first dust collector is connected to the gas inlet of the thermal oil heat exchanger. The gas outlet of the thermal oil heat exchanger is connected to the flue gas treatment system. The thermal oil outlet of the thermal oil heat exchanger is connected to the drying medium inlet of the rotary indirect dryer. The drying medium outlet of the rotary indirect dryer is connected to the thermal oil inlet of the thermal oil heat exchanger. The tertiary air outlet of the grate cooler is connected to the gas inlet of the second dust collector, and the gas outlet of the second dust collector is connected to the drying medium inlet of the belt dryer. The exhaust gas outlet of the rotary indirect dryer is connected to the gas inlet of the third dust collector, the gas outlet of the third dust collector is connected to the gas inlet of the first condensation system, the gas outlet of the first condensation system is connected to the high-temperature section gas inlet of the grate cooler, the condensate outlet of the first condensation system is connected to the water treatment system, and the outlet of the water treatment system is connected to the inlet of the oil sludge ceramsite granulation system. The first drying exhaust gas outlet of the belt dryer is connected to the gas inlet of the fourth dust collector. The gas outlet of the fourth dust collector is connected to the gas inlet of the second condensation system. The gas outlet of the second condensation system is connected to the high-temperature section gas inlet and the medium-low temperature section gas inlet of the grate cooler, respectively. The condensate outlet of the second condensation system is connected to the water treatment system. The second drying exhaust gas outlet of the belt dryer is connected to the gas inlet of the hot air furnace. The gas outlet of the hot air furnace is connected to the gas inlet of the belt dryer.

13. The production system for preparing high-performance lightweight aggregates using landfill sludge and pyrolysis residue according to claim 12, characterized in that: The flue gas treatment system includes a quench tower, a dry desulfurization tower, a bag filter, and a two-stage wet desulfurization tower. The gas outlet of the heat transfer oil heat exchanger is connected to the inlet of the quench tower, the gas outlet of the quench tower is connected to the gas inlet of the dry desulfurization tower, the gas outlet of the dry desulfurization tower is connected to the gas inlet of the bag filter, the gas outlet of the bag filter is connected to the gas inlet of the two-stage wet desulfurization tower, and the gas outlet of the two-stage wet desulfurization tower is connected to the gas inlet of the chimney.

14. The production system for preparing high-performance lightweight aggregate using landed sludge and pyrolysis residue according to claim 12, characterized in that: It also includes a natural gas hot air furnace, which is connected to the drying medium inlet of the belt dryer.

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