Sludge power generation system based on flue gas waste heat utilization

Abstract

The application discloses a sludge power generation system based on flue gas waste heat utilization, and belongs to the technical field of heterogeneous solid waste resource treatment, which comprises a sludge storage and transportation unit, a sludge anaerobic digestion unit, a sludge drying unit, a sludge pyrolysis and gasification unit, a synthetic gas purification unit and a power generation unit, wherein the sludge storage and transportation unit is used for sludge crushing and conveying, the sludge anaerobic digestion unit is used for producing and purifying biogas, and the sludge drying unit can dry sludge by using flue gas waste heat. The sludge pyrolysis and gasification unit generates synthetic gas and biochar by using sludge. The synthetic gas purification unit cools and purifies synthetic gas. The power generation unit generates power by using synthetic gas and biogas. Flue gas waste heat and sludge treatment depth are coupled, and sludge is subjected to pyrolysis treatment and anaerobic treatment, thereby generating biochar, synthetic gas and biogas. The biochar is recycled in the later period, and the synthetic gas and biogas can generate power, so that the energy utilization efficiency is improved.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of heterogeneous solid waste resource processing, in particular to a sludge power generation system based on flue gas waste heat utilization. BACKGROUND

[0002] With the acceleration of urbanization, the municipal sludge output increases year by year, but although the sludge is rich in resources, its direct utilization is greatly limited due to problems such as high water content and complex chemical structure. In the converter steelmaking process, the converter flue gas temperature can reach 300°C~550°C, which has the characteristics of continuous emission, concentrated heat, strong controllability, etc. Although some enterprises have recovered the waste heat of converter flue gas for boiler power generation or hot water heating, they are mostly concentrated on primary waste heat utilization, and the energy and quality matching efficiency is low, and a system mode deeply coupled with municipal solid waste treatment process has not yet been formed, resulting in that the utilization potential of medium and high grade waste heat has not been fully tapped.

[0003] Therefore, there is an urgent need for a technology that can deeply couple flue gas waste heat with sludge treatment and effectively utilize sludge resources. SUMMARY

[0004] The purpose of the present application is to solve the above technical problems, provide a sludge power generation system based on flue gas waste heat utilization, which not only deeply couples flue gas waste heat with sludge treatment, but also can perform pyrolysis treatment and anaerobic treatment on the sludge to generate biochar, synthesis gas and biogas, the biochar can be recycled in the later stage, and the synthesis gas and biogas can be used for power generation, realizing the synergistic conversion of energy, reduction and harmlessness of high water content sludge, and improving the overall energy utilization efficiency.

[0005] To achieve the above purpose, the present application provides the following scheme: the present application discloses a sludge power generation system based on flue gas waste heat utilization, comprising:

[0006] A sludge storage and transportation unit is used to complete sludge crushing and quantitative conveying;

[0007] A sludge anaerobic digestion unit is used to receive the crushed sludge, produce biogas through anaerobic digestion, and purify the biogas;

[0008] A sludge drying unit comprises a sludge drying device and a flue gas heat exchanger, the sludge drying device comprises a sludge inlet, a sludge outlet, a hot air inlet and a hot air outlet, the sludge inlet is used to receive the sludge conveyed by the sludge storage and transportation unit, and the sludge outlet is used to discharge the dried sludge; the flue gas heat exchanger comprises a flue gas passage and an air passage, the flue gas passage is used to pass in external flue gas, and the air passage is used to pass in external air, the waste heat of the external flue gas can heat the external air to form hot air, the hot air inlet is used to receive the hot air sent out by the air passage, and the hot air outlet is used to discharge the hot air;

[0009] a sludge pyrolysis gasification unit for receiving the sludge discharged from the sludge outlet and performing a pyrolysis gasification reaction to generate syngas and biochar;

[0010] a syngas purification unit for cooling and purifying the syngas to obtain clean syngas;

[0011] and a power generation unit for generating power by using the clean syngas and the purified biogas.

[0012] Preferably, the sludge storage and transportation unit comprises a sludge raw material storage bin, a sludge crusher, and a screw conveyor set, the feeding port of the sludge crusher is connected below the discharging port of the sludge raw material storage bin, the screw conveyor set comprises a first screw conveyor and a second screw conveyor, the feeding ports of the first screw conveyor and the second screw conveyor are both connected below the discharging port of the sludge crusher, the discharging port of the first screw conveyor is connected to the sludge inlet of the sludge drying device, and the second screw conveyor is used for conveying to the sludge anaerobic digestion unit.

[0013] Preferably, the sludge anaerobic digestion unit comprises an anaerobic digestion tank and a biogas purification device, the feeding port of the anaerobic digestion tank is connected to the discharging port of the second screw conveyor, the gas outlet of the anaerobic digestion tank is connected to the gas inlet of the biogas purification device, and the gas outlet of the biogas purification device is connected to the power generation unit.

[0014] Preferably, the sludge pyrolysis gasification unit comprises a pyrolysis gasification furnace and a sludge-based biochar storage bin, the pyrolysis gasification furnace comprises a pyrolysis furnace inlet, a pyrolysis furnace outlet, a gasification agent inlet, and a syngas outlet, the pyrolysis furnace inlet and the syngas outlet are located at the top of the pyrolysis gasification furnace, the pyrolysis furnace outlet and the gasification agent inlet are located at the bottom of the pyrolysis gasification furnace, the pyrolysis furnace inlet is connected to the sludge outlet, the pyrolysis furnace outlet is connected to the sludge-based biochar storage bin, the gasification agent inlet is used for introducing a gasification agent, and the syngas outlet is used for discharging syngas.

[0015] Preferably, the syngas purification unit comprises a cooling device and a filtering and washing device connected in sequence according to the working order.

[0016] Preferably, the sludge drying unit further comprises a dust removal device and a temperature control device, the gas inlet of the dust removal device is used for receiving external flue gas, the gas outlet of the dust removal device is connected to the upstream of the flue gas passage of the flue gas heat exchanger, and the temperature control device is installed on the sludge drying device.

[0017] Preferably, the power generation unit comprises a gas power generation module and a steam power generation module.

[0018] The gas power generation module comprises an air compressor, a combustion chamber, a gas turbine and a first power generator, the air compressor comprises a biogas inlet and an air inlet, the biogas inlet is connected with the sludge anaerobic digestion unit, a mixed gas outlet of the air compressor is connected with an air inlet of the combustion chamber, a flue gas outlet of the combustion chamber is connected with a flue gas inlet of the gas turbine, and an output shaft of the gas turbine is coaxially connected with a motor shaft of the first power generator.

[0019] The steam power generation module comprises a re-combustion device, a steam generator, a steam turbine, a condenser, a circulating pump and a second power generator, a synthesis gas inlet of the re-combustion device is connected with the sludge pyrolysis gasification unit, a flue gas inlet of the re-combustion device is connected with a flue gas outlet of the gas turbine, a flue gas outlet of the re-combustion device is connected with a heat source inlet of the steam generator, a steam outlet of the steam generator is connected with a steam inlet of the steam turbine, a steam outlet of the steam turbine is connected with a steam inlet of the condenser, a steam outlet of the condenser is connected with a feed water inlet of the steam generator through the circulating pump, and an output shaft of the steam turbine is coaxially connected with a motor shaft of the second power generator.

[0020] Preferably, the steam power generation module further comprises a preheating heat exchanger, the preheating heat exchanger comprises a heat source channel and a water source channel, a water source channel inlet end of the preheating heat exchanger is connected with the condenser, and a water source channel outlet end of the preheating heat exchanger is connected with the circulating pump; the steam generator is provided with a heat exchange chamber A, a heat exchange chamber B and a water heat exchange pipeline, the water heat exchange pipeline sequentially passes through the heat exchange chamber A and the heat exchange chamber B, a water heat exchange pipeline inlet end is connected with a feed water inlet of the steam generator, and a water heat exchange pipeline outlet end is connected with a steam inlet of the steam turbine; a heat source inlet of the heat exchange chamber A is connected with a downstream of a flue gas passage of the flue gas heat exchanger through a flue gas treatment device, a heat source inlet of the heat exchange chamber B is connected with a flue gas outlet of the re-combustion device, a heat source outlet of the heat exchange chamber A and a heat source outlet of the heat exchange chamber B are both connected with a flue gas inlet end of the heat source channel of the preheating heat exchanger through a total outlet, and a flue gas outlet end of the heat source channel of the preheating heat exchanger is connected with a purification scrubber.

[0021] Preferably, the power generation unit further comprises an organic Rankine cycle power generation module, the organic Rankine cycle power generation module comprises an evaporator, an expander, a third power generator, a condenser and a working medium pump, a heat source inlet of the evaporator is connected with a flue gas outlet end of the heat source channel of the preheating heat exchanger, a heat source outlet of the evaporator is connected with the purification scrubber, a steam outlet of the evaporator is connected with a steam inlet of the expander, an output shaft of the expander is coaxially connected with a motor shaft of the third power generator, a steam outlet of the expander is connected with an inlet end of the condenser, and an outlet end of the condenser is connected with a water source inlet of the evaporator through the working medium pump.

[0022] The application further discloses a sludge power generation method based on flue gas waste heat utilization.

[0023] The sludge storage and transportation unit breaks the sludge and quantitatively transports the sludge to the sludge drying device through a sludge inlet;

[0024] The sludge anaerobic digestion unit receives the broken sludge, produces biogas through anaerobic digestion, and purifies the biogas;

[0025] In the sludge drying unit, external flue gas and external air are introduced into the flue gas heat exchanger, the preheating of the flue gas heats the air to form hot air, the hot air is introduced into the sludge drying device through a hot air inlet to dry the sludge, then the hot air is discharged through a hot air outlet, and the dried sludge is sent to the sludge pyrolysis and gasification unit through a sludge outlet of the sludge drying device;

[0026] The sludge pyrolysis and gasification unit generates synthesis gas and biochar through pyrolysis and gasification reaction of the dried sludge;

[0027] The synthesis gas purification unit cools and purifies the synthesis gas to obtain clean synthesis gas;

[0028] The power generation unit generates power by using the biogas and the clean synthesis gas.

[0029] Compared with the prior art, the application has the following technical effects:

[0030] In the application, the sludge storage and transportation unit is used for breaking and quantitatively transporting the sludge, the sludge drying unit is used for drying the sludge by using flue gas waste heat, the sludge anaerobic digestion unit is used for receiving the broken sludge, producing biogas through anaerobic digestion, and purifying the biogas, the sludge pyrolysis and gasification unit is used for receiving the sludge and generating synthesis gas and biochar through pyrolysis and gasification reaction, the synthesis gas purification unit is used for cooling and purifying the synthesis gas to obtain clean synthesis gas, and the power generation unit is used for generating power by using the biogas and the clean synthesis gas. The flue gas waste heat and the sludge treatment are deeply coupled, the utilization potential of high-grade waste heat is fully tapped, the generation of biochar, synthesis gas and biogas by using the sludge is realized, the heterogeneous solid waste resources are converted into biochar resources and electric energy resources, the problems of resource waste and low resource utilization rate are solved, and the sludge collaborative treatment and green energy development of industrial parks and cities are promoted.

[0031] Compared with the prior art, the other technical solutions of the application have the following technical effects:

[0032] 1. The power generation unit comprises a gas power generation module and a steam power generation module, and the gas power generation part and the steam power generation part are combined to realize gas-steam combined cycle and gradient waste heat power generation, so that the energy utilization efficiency is high and the overall power generation efficiency of the system is improved.

[0033] 2. The power generation unit further comprises an organic Rankine cycle power generation module, the organic Rankine cycle power generation module is combined with the gas power generation module and the steam power generation module, the steam power generation module can further utilize the flue gas waste heat of gas-steam and the flue gas waste heat of sludge drying, realizes gas-steam-low grade waste heat three combined cycle and gradient waste heat power generation, can realize biogas and synthesis gas coupling utilization, heat and electricity multi-path gradient recovery, and is suitable for low-carbon energy integrated application of metallurgical park or municipal sludge treatment base. BRIEF DESCRIPTION OF DRAWINGS

[0034] In order to more clearly illustrate the technical solutions in the embodiments of the present application or the prior art, the drawings needed to be used in the embodiments will be briefly introduced below. Obviously, the drawings in the following description are only some embodiments of the present application, and other drawings can also be obtained according to these drawings without creative labor for those skilled in the art.

[0035] Fig. 1 It is a structural schematic diagram of the sludge power generation system based on flue gas waste heat utilization in the embodiment of the present application.

[0036] Fig. 2 It is a unified power generation flow chart of the sludge power generation system based on flue gas waste heat utilization in the embodiment of the present application.

[0037] Legend: 1, sludge raw material storage bin; 2, sludge crusher; 3, first screw conveyor; 4, second screw conveyor; 5, steel converter; 6, dust removal device; 7, flue gas heat exchanger; 8, temperature control device; 9, sludge drying device; 10, flue gas treatment device; 11, pyrolysis gasifier; 12, sludge-based biochar storage bin; 13, cooling device; 14, filtration and washing device; 15, anaerobic digestion tank; 16, biogas purification device; 17, air compressor; 18, combustion chamber; 19, gas turbine; 20, first generator; 21, afterburner; 22, steam generator; 23, steam turbine; 24, second generator; 25, condenser; 26, preheating heat exchanger; 27, circulating pump; 28, evaporator; 29, expander; 30, third generator; 31, condenser; 32, working medium pump; 33, purification washing tower. DETAILED DESCRIPTION

[0038] The technical solutions in the embodiments of the present application will be clearly and completely described below with reference to the drawings in the embodiments of the present application. Obviously, the described embodiments are only part of the embodiments of the present application, rather than all the embodiments of the present application. Based on the embodiments in the present application, all other embodiments obtained by analysis of those of ordinary skill in the art without creative work fall within the protection scope of the present application.

[0039] The present application aims to provide a sludge power generation system based on flue gas waste heat utilization to solve the problems existing in the prior art, which not only deeply couples flue gas waste heat and sludge treatment, but also pyrolyzes and anaerobically treats the sludge to generate biochar, synthesis gas and biogas, the biochar can be recycled in the later stage, and the synthesis gas and biogas can be used for power generation, realizing the energy conversion, reduction and harmless conversion of high-moisture sludge, and improving the overall energy utilization efficiency.

[0040] In order to make the above-mentioned purposes, features and advantages of the present application more apparent and easy to understand, the present application will be further described in detail below with reference to the drawings and specific embodiments.

[0041] As shown in Figs. 1-2 The present embodiment provides a sludge power generation system based on flue gas waste heat utilization, which comprises a sludge storage and transportation unit, a sludge anaerobic digestion unit, a sludge drying unit, a sludge pyrolysis and gasification unit, a synthesis gas purification unit and a power generation unit. The sludge storage and transportation unit is used to complete sludge crushing and quantitative conveying. The sludge anaerobic digestion unit is used to accept the crushed sludge, produce biogas through anaerobic digestion, and purify the biogas. The sludge drying unit comprises a flue gas heat exchanger 7 and a sludge drying device 9. The sludge drying device 9 comprises a sludge inlet, a sludge outlet, a hot air inlet and a hot air outlet. The sludge inlet is used to receive the sludge conveyed by the sludge storage and transportation unit, and the sludge outlet is used to discharge the dried sludge. The flue gas heat exchanger 7 can use flue gas waste heat to heat air to form hot air. Specifically, the flue gas heat exchanger 7 comprises a flue gas passage and an air passage. The flue gas passage is used to introduce external flue gas, and the air passage is used to introduce air. The flue gas in the flue gas passage and the air in the air passage are heat exchanged, and the air is heated by the flue gas waste heat to form hot air. The hot air inlet is used to accept the hot air sent out by the air passage of the flue gas heat exchanger 7. When the hot air enters the sludge drying device 9, it can heat and dry the sludge inside. The hot air outlet is used to discharge the hot air after heating the sludge. The sludge pyrolysis and gasification unit is used to accept the sludge discharged by the sludge outlet (sludge drying device 9) and perform pyrolysis and gasification reaction to generate synthesis gas and biochar. The synthesis gas purification unit is used to cool and purify the synthesis gas to obtain clean synthesis gas. The clean synthesis gas and the purified biogas are used for power generation.

[0042] In an embodiment, the sludge storage and transportation unit comprises a sludge raw material storage bin 1, a sludge crusher 2, and a screw conveyor set. The feeding port of the sludge crusher 2 is connected below the discharging port of the sludge raw material storage bin 1 to receive the sludge discharged from the sludge raw material storage bin 1. The screw conveyor set comprises a first screw conveyor 3 and a second screw conveyor 4, and the feeding ports of the first screw conveyor 3 and the second screw conveyor 4 are both connected below the discharging port of the sludge crusher 2 to receive the crushed sludge. The discharging port of the first screw conveyor 3 is connected to the sludge inlet of the sludge drying device 9, and the second screw conveyor 4 is used to transport sludge to the sludge anaerobic digestion unit. The working principle is as follows: the sludge first enters the sludge raw material storage bin 1 to buffer the fluctuation of the feeding. Then the sludge is treated by the sludge crusher 2 to crush the agglomerates, reduce the particle size of the large particles or cohesive sludge, increase the heat transfer area, and improve the uniformity of drying and gasification. After the crushed sludge is discharged, it is divided into two parts, one part of the sludge is transported by the first screw conveyor 3 to realize continuous and quantitative feeding to the sludge drying device 9 of the sludge drying unit. The other part of the sludge is transported by the second screw conveyor 4 to realize continuous and quantitative feeding to the sludge anaerobic digestion unit.

[0043] In an embodiment, the sludge anaerobic digestion unit comprises an anaerobic digestion tank 15 and a biogas purification device 16, the feeding port of the anaerobic digestion tank 15 is connected to the discharging port of the second screw conveyor 4, the gas outlet of the anaerobic digestion tank 15 is connected to the gas inlet of the biogas purification device 16, and the gas outlet of the biogas purification device 16 is connected to the power generation unit. The working principle is as follows: the sludge is transported by the second screw conveyor 4 to the anaerobic digestion tank 15, and after the anaerobic digestion reaction, biogas is produced, which enters the biogas purification device 16 for purification treatment, and the purified biogas is sent to the power generation unit.

[0044] In an embodiment, the anaerobic digestion tank 15 is provided with a stirring device and a temperature control device, and the reaction temperature is controlled between 30℃ and 55℃ to maintain the mesophilic or thermophilic anaerobic digestion process.

[0045] In an embodiment, the sludge pyrolysis gasification unit comprises a pyrolysis gasification furnace 11 and a sludge-based biochar storage 12. The pyrolysis gasification furnace 11 comprises a pyrolysis furnace inlet, a pyrolysis furnace outlet, a gasification agent inlet, and a synthesis gas outlet. The pyrolysis furnace inlet and the synthesis gas outlet are located at the top of the pyrolysis gasification furnace 11, and the pyrolysis furnace outlet and the gasification agent inlet are located at the bottom of the pyrolysis gasification furnace 11. The pyrolysis furnace inlet is connected to the sludge outlet of the sludge drying device 9. The pyrolysis furnace outlet is connected to the sludge-based biochar storage 12, and the gasification agent inlet is used to introduce a gasification agent (such as air or steam). The synthesis gas outlet is used to discharge synthesis gas. Working principle: after drying, the sludge enters the pyrolysis gasification furnace 11 through airtight conveying. In the pyrolysis gasification furnace 11, the temperature is controlled at 600°C-750°C. The dry sludge and the gasification agent introduced by the gasification agent inlet undergo pyrolysis and gasification reactions under anoxic conditions. During the reaction process, the organic components in the sludge are partially oxidized, pyrolyzed, and gasified under high-temperature anoxic conditions, generating synthesis gas mainly composed of carbon monoxide, hydrogen, and methane, and by-product sludge-based biochar. The biochar is discharged from the pyrolysis furnace outlet and stored in the sludge-based biochar storage 12, realizing the resource utilization of solid by-products. The synthesis gas is discharged from the synthesis gas outlet into the synthesis gas purification unit.

[0046] In the reaction environment of the pyrolysis gasification furnace 11, the core purpose is to realize the synergistic process of pyrolysis and partial gasification reactions. If the gasification agent is air, its main role is to provide partial oxygen to achieve partial oxidation and release heat to maintain the required operating temperature (600°C-750°C) in the gasification furnace. At this time, the amount of air introduced is precisely controlled, and the equivalence ratio (ER) is generally controlled between 0.2 and 0.3, which is lower than the amount of air required for complete combustion, thereby maintaining an anoxic environment in the gasification zone and avoiding complete combustion reactions. In addition, to further stabilize the anoxic state, an air / steam combined gasification mode can be used, that is, a certain proportion of steam is introduced as a gasification agent, which not only dilutes the oxygen concentration but also promotes the water-gas shift reaction (C + H2O→ CO + H2), increases the hydrogen content in the synthesis gas, and improves the gas quality. Therefore, under the premise of controlling the flow and proportion of the gasification agent, using air as the gasification agent will not destroy the anoxic environment in the gasification furnace and can improve the reaction heat self-sufficiency and system energy efficiency.

[0047] In an embodiment, the syngas purification unit comprises a cooling device 13 and a filter washing device 14, which are connected in sequence according to the working order. Specifically, the gas inlet of the cooling device 13 is connected with the syngas outlet of the sludge pyrolysis gasification unit (the pyrolysis gasification furnace 11), the gas outlet of the cooling device 13 is connected with the gas inlet of the filter washing device 14, and the gas outlet of the filter washing device 14 is connected with the power generation unit. The working principle is that: the syngas generated by pyrolysis is discharged from the syngas outlet of the pyrolysis gasification furnace 11, first passes through the cooling device 13 for cooling, and then enters the filter washing device 14, which intercepts solid particles in the syngas, such as ash, unreacted biomass char, etc., so that the syngas is cleaner, and at the same time, the syngas is sprayed and washed with water or other washing liquid, further removing residual tar, acid gas (such as hydrogen sulfide, hydrogen chloride, etc.) and other soluble impurities. After purification treatment, the quality of the syngas is significantly improved, meeting the requirements of the subsequent power generation unit.

[0048] In an embodiment, the sludge drying unit further comprises a dust removal device 6 and a temperature control device 8. The gas inlet of the dust removal device 6 is used to receive external flue gas, and the gas outlet of the dust removal device 6 is connected with the gas inlet end of the flue gas passage of the flue gas heat exchanger 7. The exhaust end of the flue gas passage of the flue gas heat exchanger 7 can be discharged after treatment, or can be subjected to other treatments, such as being introduced into the power generation unit for waste heat utilization. The temperature control device 8 is installed on the sludge drying device 9. The temperature control device 8 can monitor the temperature in the sludge drying device 9 and control the air outlet gas flow of the air passage, so as to control the hot air supply and realize temperature regulation. The working principle is that: the high-temperature flue gas first removes dust particles through the dust removal device 6, and then heats the air through the flue gas heat exchanger 7. The obtained hot air is supplied to the drying device under the regulation of the temperature control device 8, so as to realize the sludge hot air drying treatment.

[0049] In an embodiment, the dust removal device 6 adopts one of an inertia dust collector, a cyclone dust collector, a bag dust collector and an electrostatic dust collector.

[0050] In an embodiment, the temperature control device 8 comprises a plurality of temperature control probes, which can feedback the hot air temperature in real time and automatically adjust the heating power, so as to realize uniform drying of the sludge, and the moisture content of the outlet sludge is reduced to about 20%. The dried material is discharged from the dry material outlet of the drying equipment and is ready to enter the next process. The flue gas after waste heat utilization is discharged to the atmosphere after desulfurization and purification treatment.

[0051] In an embodiment, the temperature control device 8 can be a Siemens S7-1500 series PLC control system, combined with multiple PT100 thermistor temperature sensors (temperature control probes) and electrically adjusted air valves, to build a precise temperature control network. The temperature control device 8 has multiple loop PID regulation functions, which can independently regulate the temperature and air volume of multiple drying areas in the sludge drying device 9, ensuring the uniformity and efficiency of the sludge drying process.

[0052] In an embodiment, the sludge drying device 9 can use the "BSDH-800 type sludge low-temperature belt dryer" produced by the Bopuren Environmental Protection Company or similar equipment. Multiple temperature control probes are arranged along the conveying direction of the conveying belt of the sludge drying device 9. The equipment uses a closed low-temperature hot air circulation technology, with a hot air temperature control range of 60°C~120°C, high thermal efficiency and good adaptability, suitable for stable drying treatment of municipal and industrial sludge. During equipment operation, temperature zoning regulation and dynamic feedback adjustment are realized in combination with the temperature control device 8, thereby optimizing drying efficiency and system energy consumption.

[0053] In an embodiment, the external flue gas is the flue gas of the steel converter 5. Of course, it can also be the flue gas of other boilers or other equipment. A large amount of high-temperature flue gas (about 300°C~550°C) generated during the steelmaking process of the steel converter 5 is introduced into the flue gas passage of the flue gas heat exchanger 7 through a pipeline, and the flue gas heat exchanger 7 transfers the flue gas heat to the air in the air passage to form hot air, which is sent to the sludge drying device 9 after adjusting the air volume by the temperature control device 8.

[0054] In an embodiment, the cooling device 13 uses an indirect cooling method, such as circulating cooling water in the coil of the cooler to reduce the temperature of the synthesis gas to about 120°C, and preliminarily condense and remove tar and moisture.

[0055] In an embodiment, the power generation unit includes a gas power generation module and a steam power generation module.

[0056] The gas power generation module includes an air compressor 17, a combustion chamber 18, a gas turbine 19, and a first generator 20. The air compressor 17 includes a biogas inlet and an air inlet, and the biogas inlet is connected to the sludge anaerobic digestion unit (such as the gas outlet of the biogas purification device 16). The mixed gas outlet of the air compressor 17 is connected to the air inlet of the combustion chamber 18, and the flue gas outlet of the combustion chamber 18 is connected to the flue gas inlet of the gas turbine 19. The output shaft of the gas turbine 19 is coaxially connected to the motor shaft of the first generator 20.

[0057] The steam power generation module comprises a combustor 21, a steam generator 22, a steam turbine 23, a condenser 25, a circulating pump 27 and a second generator 24. The syngas inlet of the combustor 21 is connected with the sludge pyrolysis gasification unit (for example, the gas outlet of the filter washing device 14). The flue gas inlet of the combustor 21 is connected with the flue gas outlet of the gas turbine 19, and the flue gas outlet of the combustor 21 is connected with the heat source inlet of the steam generator 22. The steam outlet of the steam generator 22 is connected with the steam inlet of the steam turbine 23, and the steam outlet of the steam turbine 23 is connected with the steam inlet of the condenser 25. The steam outlet of the condenser 25 is connected with the feed water inlet of the steam generator 22 through the circulating pump 27, and the output shaft of the steam turbine 23 is coaxially connected with the motor shaft of the second generator 24.

[0058] Working principle: After the purified biogas and clean syngas enter the power generation unit, the purified biogas will be introduced into the air compressor 17, while the fresh air from the environment is compressed to the required pressure (usually 0.5 MPa~1.5 MPa) by the air compressor 17. The compressed air temperature rises, and the compressed air is introduced into the combustion chamber 18. The compressed air and the compressed biogas are mixed in the combustion chamber 18 according to the set flow rate and proportion. In this combustion process, the biogas reacts with the compressed air to produce high-temperature and high-pressure flue gas, and the typical combustion temperature range is 1000°C~1500°C. The flue gas after combustion carries a large amount of heat energy. The high-temperature and high-pressure flue gas enters the gas turbine 19, which drives the turbine blades of the gas turbine 19 to rotate at high speed, thereby driving the output shaft to rotate, and converting the heat energy of the flue gas into mechanical energy to drive the first generator 20 connected with the shaft to generate electricity. This process constitutes the gas power generation link. The gas turbine 19 has the characteristics of rapid start and stop and flexible load response, and is suitable for the combustion characteristics of syngas with variable quality. The power generation power can reach several megawatts according to the system scale. The flue gas (temperature about 400°C~600°C) in the gas turbine 19 that drives the turbine blades to rotate and work is introduced into the combustor 21 for combustion. The excess air coefficient of the gas turbine 19 is large, and the oxygen content in the exhaust gas of the gas turbine 19 is sufficient, which can be sent to the combustor 21 for supplemental combustion.

[0059] Meanwhile, the clean synthesis gas enters the combustor 21, and is combusted together with the exhaust gas of the gas turbine 19 to increase the heat value of the combustion flue gas, and then the high-temperature flue gas (600-800℃) in the combustor 21 is introduced into the steam generator 22 for further utilization. The device is internally arranged with water heat exchange pipelines, and the water absorbs the heat of the high-temperature flue gas during the flow in the water heat exchange pipelines, and gradually evaporates to generate high-temperature steam. The pressure and temperature of the steam are determined according to the design parameters of the steam generator 22. The generated steam enters the steam turbine 23, and drives the blades of the steam turbine 23 to rotate to work, and then drives the transmission shaft to rotate to drive the second generator 24 to rotate to generate electricity, and further converts the heat energy of the steam into mechanical energy, so as to realize the secondary energy conversion of the waste heat. This process constitutes the steam power generation link of the combined cycle. The power generation unit forms a gas-steam combined cycle power generation system. The steam discharged from the steam turbine 23 is condensed into water through the condenser 25, and the condensed water is sent back to the steam generator 22 through the circulating pump 27 to form a closed steam-water circulation loop. Through the two-stage energy conversion of the gas-steam, the thermal energy utilization efficiency can reach 45%-55%, which is significantly higher than that of a single combustion or steam power generation circuit.

[0060] In an embodiment, the steam power generation module further comprises a preheating heat exchanger 26, the preheating heat exchanger 26 comprises a heat source channel and a water source channel, the water source channel is connected with the condenser 25 at the liquid inlet end. The water source channel is connected with the circulating pump 27 at the liquid outlet end. The steam generator 22 is internally provided with a heat exchange chamber A, a heat exchange chamber B and a water heat exchange pipeline, the water heat exchange pipeline sequentially passes through the heat exchange chamber A and the heat exchange chamber B, the inlet end of the water heat exchange pipeline is connected with the water inlet of the steam generator, and the outlet end of the water heat exchange pipeline is connected with the steam inlet of the steam turbine 23; the heat source inlet of the heat exchange chamber A is connected with the downstream of the flue gas passage of the flue gas heat exchanger 7 through the flue gas treatment device 10, the heat exchange chamber A is used for receiving the purified medium-temperature flue gas to preheat the water or to preliminarily evaporate. The heat source inlet of the heat exchange chamber B is connected with the flue gas outlet of the combustor 21, and is used for receiving the high-temperature flue gas discharged from the combustor 21 to complete the steam superheating process. The heat source outlet of the heat exchange chamber A and the heat source outlet of the heat exchange chamber B are both connected with the gas inlet end of the heat source channel of the preheating heat exchanger 26 through the total outlet, and the gas outlet end of the heat source channel of the preheating heat exchanger 26 is connected with the purification washing tower 33.

[0061] Working principle: the heat-exchanged flue gas in the flue gas passage of the flue gas heat exchanger 7 enters the flue gas treatment device 10 to remove SO2, NO xand other harmful components, and then enters the heat exchange chamber A of the steam generator 22 to preheat or preliminarily evaporate the water, while the flue gas in the combustor 21 is discharged into the heat exchange chamber B of the steam generator 22 to heat the preheated water into water vapor, and the high-temperature water vapor enters the steam turbine 23 through the water heat exchange pipeline to rotate the blades of the steam turbine 23 to generate power to drive the second generator 24 to generate electricity. The flue gas in the heat exchange chamber A and the heat exchange chamber B is discharged through the total outlet into the heat source channel of the preheating heat exchanger 26 to preheat the condensed water delivered by the condenser 25 received by the water source channel of the preheating heat exchanger 26, and the preheated condensed water enters the water heat exchange pipeline again through the feedwater inlet of the steam generator 22 to circulate, so that the preheated condensed water can accelerate the speed of forming water vapor. The flue gas in the heat source channel of the preheating heat exchanger 26 is discharged after being purified in the purification scrubber 33.

[0062] In an embodiment, the power generation unit further comprises an organic Rankine cycle power generation module, which comprises an evaporator 28, an expander 29, a third generator 30, a condenser 31 and a working fluid pump 32, the heat source inlet of the evaporator 28 is connected with the gas outlet end of the heat source channel of the preheating heat exchanger 26, and the heat source outlet of the evaporator 28 is connected with the purification scrubber 33. The steam outlet of the evaporator 28 is connected with the steam inlet of the expander 29, the output shaft of the expander 29 is coaxially connected with the motor shaft of the third generator 30. The steam outlet of the expander 29 is connected with the inlet end of the condenser 31, and the outlet end of the condenser 31 is connected with the water source inlet of the evaporator 28 through the working fluid pump 32.

[0063] Working principle: the flue gas in the heat source channel of the preheating heat exchanger 26 is first discharged into the evaporator 28 to heat the water source to form water vapor, and the water vapor enters the expander 29 to rotate the output shaft of the expander 29 to drive the motor shaft of the third generator 30 to rotate to generate electricity. The low-grade waste heat is reused. The gas power generation module, the steam power generation module and the low-grade waste heat form a combined cycle and cascade waste heat power generation, the system structure is compact, the biogas and the synthesis gas can be coupled and utilized, the heat and electricity can be recovered in multiple paths, and the system is suitable for low-carbon energy integrated application in a metallurgical park or a municipal sludge treatment base.

[0064] In an embodiment, the combustor 18 adopts a flame stabilizing structure and has high-efficiency mixing and low-NOx emission characteristics.

[0065] In an embodiment, a deaerator is arranged between the circulating pump 27 and the steam generator 22 to deaerate the condensed water before the condensed water is returned to the steam generator 22.

[0066] In an embodiment, an external water source is also connected between the condenser 25 and the circulating pump 27. The condensate water and the make-up water from the external water source are mixed, and then pumped back to the steam generator 22 to complete the steam-water cycle, realize efficient recovery of waste heat, and improve the efficiency of the entire power generation system. The total energy utilization efficiency of the power generation unit is not less than 45%, and the biochar byproduct can be used as a solid fuel or a soil conditioner for resource utilization.

[0067] In an embodiment, the organic working fluid circulating in the organic Rankine cycle power generation module is selected from R123, R245fa or other low-boiling environmentally friendly organic fluids, the evaporation temperature is controlled at 80-140°C, and the condensation temperature is controlled at 30-45°C, for efficient recovery of low-grade flue gas waste heat.

[0068] The sludge power generation system based on flue gas waste heat utilization is based on the multi-path step-by-step energy release mechanism of high-grade waste heat in the steel industry, realizes the synergistic resource utilization of sludge drying, pyrolysis, and anaerobic digestion gas production, and integrates the three types of power generation modules of gas turbine + steam turbine + ORC (organic Rankine cycle power generation module) to build a multi-energy complementary power generation system for industrial parks, improve the overall energy cascade utilization efficiency and solid waste synergistic disposal level, and promote the green and low-carbon integrated development of the steel industry and the municipal system. Embodiment

[0069] As shown in Figs. 1-2 The embodiment provides a sludge power generation method based on flue gas waste heat utilization, which adopts the sludge power generation system based on flue gas waste heat utilization in embodiment 1, and comprises the following steps:

[0070] The sludge storage and transportation unit breaks the sludge and quantitatively transports the sludge to the sludge drying device 9 through a sludge inlet.

[0071] The sludge anaerobic digestion unit receives the broken sludge, produces biogas through anaerobic digestion, and purifies the biogas;

[0072] In the sludge drying unit, external flue gas and external air are introduced into the flue gas heat exchanger 7, the preheating of the flue gas heats the air to form hot air, the hot air is introduced into the sludge drying device 9 through a hot air inlet to dry the sludge, and then the hot air is discharged from a hot air outlet, and the dried sludge is sent to the sludge pyrolysis and gasification unit through a sludge outlet of the sludge drying device 9.

[0073] The sludge pyrolysis and gasification unit performs pyrolysis and gasification reaction on the dried sludge to generate synthesis gas and biochar.

[0074] The synthesis gas purification unit cools and purifies the synthesis gas to obtain clean synthesis gas.

[0075] The power generation unit generates power by using the biogas and the clean synthesis gas.

[0076] In an embodiment, the sludge power generation method based on flue gas waste heat utilization comprises the following steps:

[0077] The gas power generation module utilizes clean biogas combustion to generate high-temperature flue gas, drives the gas turbine 19 and the first generator 20 to generate power;

[0078] The steam power generation module utilizes the high-temperature flue gas after re-combustion to drive the steam turbine 23 and the second generator 24 to generate power;

[0079] The organic Rankine cycle power generation module recovers the heat energy in the medium-low temperature tail gas, circulates through the working medium, drives the expander 29 and the third generator 30 to generate power.

[0080] In an embodiment, the specific steps include the following:

[0081] Step one, the sludge enters the sludge raw material storage bin 1, and then is processed by the sludge crusher 2 to be broken into lumps. The broken sludge is continuously and quantitatively fed to the sludge drying device 9 through the first screw conveyor 3, and is continuously and quantitatively fed to the anaerobic digester 15 through the second screw conveyor 4;

[0082] Step two, the sludge transported by the second screw conveyor 4 is subjected to anaerobic digestion reaction in the anaerobic digester 15 to produce biogas. The biogas enters the biogas purification device 16 for purification treatment, so as to send the purified biogas to the air compressor 17. At the same time, the sludge transported by the first screw conveyor 3 enters the sludge drying device 9. A large amount of high-temperature flue gas (about 300°C~400°C) generated in the steelmaking process of the steel converter 5 first removes dust particles through the dust removal device 6, and then enters the flue gas passage of the flue gas heat exchanger 7. The flue gas heat exchanger 7 transfers the heat of the flue gas to the air in the air passage to form hot air. The hot air is sent into the sludge drying device 9 after the air volume is adjusted by the temperature control device 8, and the sludge in the sludge drying device 9 is heated and dried (the moisture content of the sludge is reduced from 80% to 20%~30%). The temperature control device 8 monitors the temperature in the sludge drying device 9 and controls the hot air volume of the air passage, so as to control the temperature in the sludge drying device 9. The gas discharged from the flue gas passage enters the flue gas treatment device 10 to remove SO2, NO xand other harmful components, and then enters the steam generator 22; the dried sludge is transported into the pyrolysis gasifier 11 in a sealed manner, and in the pyrolysis gasifier 11, the temperature is controlled at 600°C-750°C; the dry sludge and the gasification agent introduced thereinto are subjected to pyrolysis and gasification reactions under anoxic conditions; in the reaction process, the organic components in the sludge are partially oxidized, pyrolyzed and gasified under the high-temperature and anoxic environment, to generate synthesis gas mainly composed of carbon monoxide, hydrogen and methane, and by-product sludge-based biochar; the biochar is discharged from the outlet of the pyrolysis furnace and stored in the sludge-based biochar storage bin 12; the synthesis gas is discharged into the cooling device 13, which cools the synthesis gas; the cooled synthesis gas enters the filtration and washing device 14, which intercepts solid particles in the synthesis gas, so that the synthesis gas is cleaner; at the same time, the synthesis gas is sprayed and washed with water or other washing liquid, to further remove residual tar, acid gas (such as hydrogen sulfide, hydrogen chloride, etc.) and other soluble impurities; and the purified synthesis gas enters the afterburner 21.

[0083] Step three, the biogas and fresh air from the environment are compressed to the required pressure (usually 0.5MPa-1.5MPa) by the air compressor 17, and the compressed air temperature rises; the compressed air and the compressed biogas are mixed in the combustion chamber 18 according to the set flow rate and proportion; in the combustion process, the biogas and the compressed air react to generate high-temperature and high-pressure flue gas, and the typical combustion temperature range is 1000°C-1500°C; the flue gas after combustion carries a large amount of heat energy; the high-temperature and high-pressure flue gas enters the gas turbine 19, which drives the turbine blades of the gas turbine 19 to rotate at high speed, thereby driving the output shaft to rotate, converting the heat energy of the flue gas into mechanical energy, driving the first generator 20 connected to the rotating shaft to generate electricity; the flue gas (temperature about 400°C-600°C) after work done in the gas turbine 19 is introduced into the afterburner 21, and the clean synthesis gas is introduced into the afterburner 21 to perform afterburning; then the high-temperature flue gas (temperature 600°C-800°C) in the afterburner 21 is introduced into the heat exchange chamber B of the steam generator 22; the flue gas after SO2, NOx and dust removal by the flue gas treatment device 10 is introduced into the heat exchange chamber A of the steam generator 22, and the heat energy of the flue gas is transferred to the water in the heat exchange chamber A to generate high-pressure and high-temperature steam. xand other harmful ingredients, and then enters the heat exchange chamber A of the steam generator 22 to preheat or preliminarily evaporate the water. The flue gas discharged by the supplementary combustor 21 into the heat exchange chamber B heats the preheated water into water vapor. The high-temperature water vapor enters the steam turbine 23 through the water heat exchange pipeline, pushes the blades of the steam turbine 23 to rotate and work, so as to drive the second generator 24 to rotate and generate electricity. The steam discharged by the steam turbine 23 is condensed into water by the condenser 25. The flue gas in the heat exchange chamber A and the heat exchange chamber B is discharged into the heat source channel of the preheating heat exchanger 26 through the total outlet, preheats the condensed water delivered by the condenser 25 and received by the water source channel of the preheating heat exchanger 26, and the preheated condensed water enters the water heat exchange pipeline again through the circulating pump 27 and the feedwater inlet of the steam generator 22 to circulate. The preheated condensed water can accelerate the speed of forming water vapor. The flue gas in the heat source channel of the preheating heat exchanger 26 is discharged into the evaporator 28 of the organic Rankine cycle power generation module.

[0084] Step four, after the flue gas of the preheating heat exchanger 26 is discharged into the evaporator 28, the water source in the evaporator 28 is heated to form water vapor, which enters the expander 29 to realize the rotation of the output shaft of the expander 29, drive the motor shaft of the third generator 30 to rotate and realize power generation. The steam that has done work in the expander 29 is discharged into the condenser 31 to form condensed water, and then is circulated back to the evaporator 28 through the working fluid pump 32. The flue gas that has completed heat exchange in the evaporator 28 is finally discharged into the purification scrubbing tower 33 for purification and then discharged.

[0085] The method and the system have the following advantages:

[0086] ①Realize the multi-energy coupling and cooperation of sludge drying, pyrolysis, anaerobic, biogas utilization, steam power generation and ORC power generation, and build an integrated cascade power generation system;

[0087] ②Effectively match the multi-stage heat energy structure of high-grade flue gas of a steel converter, medium-grade supplementary combustion flue gas and low-grade tail gas, and improve the depth of waste heat recovery;

[0088] ③Use the oxygen-rich characteristics of the exhaust gas of the gas turbine to realize low-pressure supplementary combustion of synthesis gas, without the need for high-pressure compression of synthesis gas, thereby reducing the complexity and operating cost of the system and the method;

[0089] ⑤The byproduct biochar can be used as a solid fuel or a soil improvement material, realizing the maximum utilization of sludge resources;

[0090] ⑥The total power generation efficiency of the system and the method is not less than 45%, the energy output per unit of sludge treatment is high, and the environmental and economic benefits are significant.

[0091] The principles and implementation manners of the present application are described by using specific examples in the present application, and the above examples are only used for helping to understand the method of the present application and its core idea; meanwhile, for the general technical personnel in the art, the specific implementation manners and application ranges will be changed according to the idea of the present application. In conclusion, the content of the specification should not be understood as the limitation of the present application.

Claims

1. A sludge power generation system based on flue gas waste heat utilization, characterized in that, include: A sludge storage and transportation unit, which is used to complete sludge crushing and quantitative transportation; The sludge anaerobic digestion unit is used to receive crushed sludge, perform anaerobic digestion to produce biogas, and purify the biogas. The sludge drying unit includes a sludge drying device and a flue gas heat exchanger. The sludge drying device includes a sludge inlet, a sludge outlet, a hot air inlet, and a hot air outlet. The sludge inlet receives the sludge transported by the sludge storage and transportation unit, and the sludge outlet discharges the dried sludge. The flue gas heat exchanger includes a flue gas passage and an air passage. The flue gas passage is used to introduce external flue gas, and the air passage is used to introduce external air. The waste heat of the external flue gas can heat the external air to form hot air. The hot air inlet receives the hot air delivered from the air passage, and the hot air outlet discharges the hot air. The sludge pyrolysis and gasification unit is used to receive the sludge discharged from the sludge outlet and carry out pyrolysis and gasification reactions to generate syngas and biochar. Syngas purification unit is used to cool and purify syngas to obtain clean syngas; And a power generation unit for generating electricity using clean syngas and purified biogas; The power generation unit includes a gas-fired power generation module, a steam power generation module, and an organic Rankine cycle power generation module. The gas-fired power generation module includes an air compressor, a combustion chamber, a gas turbine, and a first generator. The air compressor includes a biogas inlet and an air inlet. The biogas inlet is connected to the sludge anaerobic digestion unit. The mixed gas outlet of the air compressor is connected to the air inlet of the combustion chamber. The flue gas outlet of the combustion chamber is connected to the flue gas inlet of the gas turbine. The output shaft of the gas turbine is coaxially connected to the motor shaft of the first generator. The steam power generation module includes a burner, a steam generator, a steam turbine, a condenser, a preheating heat exchanger, a circulating pump, and a second generator. The syngas inlet of the burner is connected to the sludge pyrolysis gasification unit, the flue gas inlet of the burner is connected to the flue gas outlet of the gas turbine, the flue gas outlet of the burner is connected to the heat source inlet of the steam generator, the steam outlet of the steam generator is connected to the steam inlet of the steam turbine, the steam outlet of the steam turbine is connected to the steam inlet of the condenser, the steam outlet of the condenser is connected to the feedwater inlet of the steam generator through the circulating pump, and the output shaft of the steam turbine is coaxially connected to the motor shaft of the second generator. The organic Rankine cycle power generation module includes an evaporator, an expander, a third generator, a purification and scrubbing tower, a condenser, and a working fluid pump. The heat source inlet of the evaporator is connected to the outlet end of the heat source channel of the preheating heat exchanger. The heat source outlet of the evaporator is connected to the purification and scrubbing tower. The steam outlet of the evaporator is connected to the steam inlet of the expander. The output shaft of the expander is coaxially connected to the motor shaft of the third generator. The steam outlet of the expander is connected to the inlet end of the condenser. The outlet end of the condenser is connected to the water source inlet of the evaporator through the working fluid pump.

2. The sludge power generation system based on flue gas waste heat utilization according to claim 1, characterized in that, The sludge storage and transportation unit includes a sludge raw material storage silo, a sludge crusher, and a screw conveyor assembly. The inlet of the sludge crusher is connected below the outlet of the sludge raw material storage silo. The screw conveyor assembly includes a first screw conveyor and a second screw conveyor. The inlets of both the first and second screw conveyors are connected below the outlet of the sludge crusher. The outlet of the first screw conveyor is connected to the sludge inlet of the sludge drying device. The second screw conveyor is used to transport sludge to the anaerobic digestion unit.

3. The sludge power generation system based on flue gas waste heat utilization according to claim 2, characterized in that, The sludge anaerobic digestion unit includes an anaerobic digester and a biogas purification device. The inlet of the anaerobic digester is connected to the outlet of the second screw conveyor, the outlet of the anaerobic digester is connected to the inlet of the biogas purification device, and the outlet of the biogas purification device is connected to the power generation unit.

4. The sludge power generation system based on flue gas waste heat utilization according to claim 1, characterized in that, The sludge pyrolysis gasification unit includes a pyrolysis gasification furnace and a sludge-based biochar storage silo. The pyrolysis gasification furnace includes a pyrolysis furnace inlet, a pyrolysis furnace outlet, a gasifying agent inlet, and a syngas outlet. The pyrolysis furnace inlet and the syngas outlet are located at the top of the pyrolysis gasification furnace, and the pyrolysis furnace outlet and the gasifying agent inlet are located at the bottom of the pyrolysis gasification furnace. The pyrolysis furnace inlet is connected to the sludge outlet, and the pyrolysis furnace outlet is connected to the sludge-based biochar storage silo. The gasifying agent inlet is used to introduce the gasifying agent, and the syngas outlet is used to discharge syngas.

5. The sludge power generation system based on flue gas waste heat utilization according to claim 1 or 4, characterized in that, The syngas purification unit includes a cooling device and a filtration and washing device connected sequentially in the working order.

6. The sludge power generation system based on flue gas waste heat utilization according to claim 1, characterized in that, The sludge drying unit also includes a dust removal device and a temperature control device. The air inlet of the dust removal device is used to receive external flue gas, and the air outlet of the dust removal device is connected to the upstream of the flue gas passage of the flue gas heat exchanger. The temperature control device is installed on the sludge drying device.

7. The sludge power generation system based on flue gas waste heat utilization according to claim 1, characterized in that, The preheating heat exchanger includes a heat source channel and a water source channel. The inlet end of the water source channel of the preheating heat exchanger is connected to the condenser, and the outlet end of the water source channel of the preheating heat exchanger is connected to the circulating pump. The steam generator is provided with heat exchange chamber A, heat exchange chamber B, and water heat exchange pipes. The water heat exchange pipes pass through heat exchange chamber A and heat exchange chamber B in sequence. The inlet end of the water heat exchange pipes is connected to the feed water inlet of the steam generator, and the outlet end of the water heat exchange pipes is connected to the steam inlet of the steam turbine. The heat source inlet of heat exchange chamber A is connected to the downstream of the flue gas passage of the flue gas heat exchanger through a flue gas treatment device. The heat source inlet of heat exchange chamber B is connected to the flue gas outlet of the burner. The heat source outlets of heat exchange chamber A and heat exchange chamber B are both connected to the air inlet end of the heat source channel of the preheating heat exchanger through a total outlet.

8. A sludge power generation method based on flue gas waste heat utilization, characterized in that, The sludge power generation system based on flue gas waste heat utilization as described in any one of claims 1-7 includes the following steps: The sludge storage and transportation unit crushes the sludge and quantitatively delivers it to the sludge drying unit through the sludge inlet. The sludge anaerobic digestion unit receives crushed sludge, performs anaerobic digestion to produce biogas, and then purifies the biogas. In the sludge drying unit, external flue gas and external air are introduced into the flue gas heat exchanger. The preheating of the flue gas heats the air to form hot air. The hot air is introduced into the sludge drying device through the hot air inlet to dry the sludge. Then the hot air is discharged from the hot air outlet. The dried sludge is sent to the sludge pyrolysis gasification unit through the sludge outlet of the sludge drying device. The sludge pyrolysis and gasification unit pyrolyzes and gasifies the dried sludge to produce syngas and biochar. The syngas purification unit cools and purifies the syngas to obtain clean syngas; The power generation unit uses biogas and clean syngas to generate electricity.

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