A sludge incineration tail gas treatment system and an energy storage heat exchanger

Abstract

The present invention relates to the technical field of energy utilization and energy conservation and emission reduction, and discloses a sludge incineration tail gas treatment system and an energy storage heat exchanger. The system includes a tail gas purification module, a carbon capture and solidification module, a circulation power generation module, an air dehumidification heat pump module, and a cascade energy storage module. The tail gas purification module is used to sequentially perform particulate matter filtration, desulfurization, electrostatic dust removal, and denitrification treatment on the tail gas discharged from the incinerator; the carbon capture and solidification module is used to collect CO2 in the tail gas through temperature swing adsorption and low-temperature cooling technology; the circulation power generation module is used to convert low-grade waste heat in the tail gas into electrical energy through organic Rankine cycle technology; the air dehumidification heat pump module is used to dehumidify and preheat the air entering the incinerator; and the cascade energy storage module is used to grade the waste heat in different temperature zones in the tail gas during the purification process. The present invention achieves efficient removal of multiple pollutants in the tail gas, and graded recovery and utilization of waste heat at different temperature levels.

Description

Technical Field

[0001] The present invention relates to the technical field of energy utilization and energy conservation and emission reduction, and in particular to a sludge incineration tail gas treatment system and an energy storage heat exchanger. Background Art

[0002] As a crucial component of municipal solid waste management, sludge disposal is receiving significant attention for its resource utilization, volume reduction, and harmless treatment. Incineration, the current mainstream method for sludge volume reduction, has been widely promoted due to its advantages, including minimal land use, high volume reduction rates, and energy recovery.

[0003] The high-temperature tail gas generated during sludge incineration contains a large amount of pollutants, such as sulfur dioxide (SO2), nitrogen oxides (NO x ), particulate matter (PM), carbon dioxide (CO2) and heavy metal elements, etc., which have the characteristics of high temperature, complex composition and great difficulty in treatment. The current mainstream tail gas treatment system focuses more on the purification of pollutants itself, and the emission of greenhouse gases such as CO2 is insufficiently controlled, and the waste heat utilization rate is low, resulting in poor overall energy efficiency and difficulty in meeting the requirements of green and low-carbon development. In addition, the high moisture content in the incineration air will also seriously affect the efficiency of the system: on the one hand, it reduces the calorific value of sludge combustion, and on the other hand, it increases the water vapor content in the tail gas, aggravating equipment corrosion, especially in the case of acidic gases (SO2, NO x ) is condensed, it is more likely to cause low-temperature corrosion problems, affecting the long-term operational stability of the system. Traditional exhaust heat exchange equipment mostly uses shell and tube heat exchangers, which have significant limitations in dealing with high-particle and highly corrosive exhaust gases. Particulate matter and heavy metals are easily accumulated and deposited inside the heat transfer tubes, causing blockage, increased pressure drop, and decreased heat exchange efficiency. Frequent maintenance or replacement is required, which greatly affects the economic efficiency of the system operation. Therefore, it is urgent to develop a new type of heat exchange equipment that has anti-clogging ability, is suitable for harsh exhaust environments, and has cascade thermal energy storage capabilities, and to build an integrated exhaust treatment system to synergistically achieve the dual goals of pollution control and energy recovery. Summary of the Invention

[0004] In order to solve the technical problems existing in the prior art, the present invention provides a sludge incineration exhaust gas treatment system and an energy storage heat exchanger. The system takes the energy storage heat exchanger as the core unit, integrates the functions of exhaust gas purification, cascade waste heat energy storage, carbon capture and solidification, circulating power generation and air dehumidification and preheating, realizes the efficient removal of various pollutants in the exhaust gas, and carries out graded recovery and utilization of waste heat of different temperature levels.

[0005] To achieve the above object, the present invention provides the following technical solutions:

[0006] The invention discloses a sludge incineration tail gas treatment system, comprising: a tail gas purification module, a carbon capture and solidification module, a circulating power generation module, an air dehumidification heat pump module and a cascade energy storage module.

[0007] The tail gas purification module is used to perform particulate matter filtration, desulfurization, electrostatic dust removal and denitrification on the tail gas discharged from the incinerator in sequence;

[0008] The carbon capture and solidification module is used to collect CO2 from exhaust gas through temperature swing adsorption and cryogenic cooling technology;

[0009] The cycle power generation module is used to convert low-grade waste heat in tail gas into electrical energy through organic Rankine cycle technology;

[0010] The air dehumidification heat pump module is used to dehumidify and preheat the air entering the incinerator;

[0011] The cascade energy storage module is used to recover and manage the waste heat in different temperature zones in the exhaust gas in a graded manner during the purification process; the cascade energy storage module includes energy storage heat exchanger 1, energy storage heat exchanger 2, energy storage heat exchanger 3 and energy storage heat exchanger 4; wherein, energy storage heat exchanger 1 is used to cool the exhaust gas after the particulate matter filtration treatment to above the first temperature threshold and store high-grade waste heat; energy storage heat exchanger 2 is used to cool the exhaust gas after the energy storage heat exchanger 1 is cooled to above the second temperature threshold and store low-grade waste heat; energy storage heat exchanger 1 and energy storage heat exchanger 2 also use their own stored waste heat to recover the waste heat after the particulate matter filtration treatment. The exhaust gas after electrostatic dust removal and desulfurization gradually rises to above the first temperature threshold for denitrification treatment, and the exhaust gas is heated after denitrification; the energy storage heat exchanger three is used to cool the exhaust gas after denitrification to above the first temperature threshold and store high-grade waste heat, and at the same time use the waste heat to convert the low-boiling-point working medium in the circulating power generation module from liquid to steam; the energy storage heat exchanger four is used to cool the exhaust gas after the energy storage heat exchanger three is cooled to above the second temperature threshold and store low-grade waste heat, and at the same time use the waste heat to further heat the dehumidified and preheated air of the air dehumidification heat pump module to send it into the incinerator.

[0012] As a further improvement of the above scheme, all energy storage heat exchangers are internally provided with independent shell side and tube side. The shell side is used to circulate the cold medium, and the tube side is used to circulate the hot medium. An energy storage medium is also provided between the shell side and the tube side for absorbing heat from the hot medium and releasing it to the cold medium.

[0013] As a further improvement to the above solution, the exhaust gas purification module includes a bag filter, a desulfurization tower, an electrostatic precipitator and a denitrification tower, which are respectively used to filter particulate matter, desulfurize, remove electrostatic dust and denitrify the exhaust gas; the exhaust gas purification module also includes an induced draft fan that provides power for exhaust gas transmission;

[0014] The carbon capture and solidification module includes a carbon capture device, a refrigeration unit, a liquid storage tank, and a freezer. The carbon capture device uses temperature swing adsorption technology to drive the adsorbent to selectively adsorb and desorb CO2 at different temperatures. The desorbed CO2 is sent to the refrigeration unit for liquefaction and stored in the liquid storage tank. The CO2 is converted into dry ice through a low-temperature cooling process and stored in the freezer.

[0015] The cycle power generation module includes a steam turbine, a generator, a regenerator, an exhaust tower and a centrifugal pump; wherein, the low-boiling-point working medium is heated and converted into steam in the shell side of the energy storage heat exchanger 3, and then enters the steam turbine to drive the turbine impeller to rotate, thereby driving the coupled generator to generate electricity; after the low-boiling-point working medium steam loses energy in doing work, it passes through the regenerator to exchange waste heat with the cooled tail gas that has collected CO2 to condense into liquid, and then is transported back to the shell side of the energy storage heat exchanger 3 by the centrifugal pump, and the tail gas after the waste heat exchange is discharged to the atmosphere through the exhaust tower (18);

[0016] The air dehumidification heat pump module includes a blower, a compressor, an evaporator, an expansion valve, and a condenser, which are connected in sequence to form a refrigerant circulation system. The refrigerant passes through the expansion valve, evaporator, compressor, and condenser in sequence to complete the reverse Carnot cycle and exchange heat with the fresh air sent in by the blower; the air is cooled to a temperature below the dew point in the evaporator, thereby dehumidifying by extracting water, and then preheated through the condenser.

[0017] As a further improvement of the above solution, the cascade energy storage module further includes a buffer tank 1, a switch valve 1, a buffer tank 2 and a switch valve 2;

[0018] Among them, according to the transmission direction of the exhaust gas, the exhaust gas outlet of the incinerator, the bag dust collector, the induced draft fan, the pipe side of the energy storage heat exchanger one, the pipe side of the energy storage heat exchanger two, the buffer tank one, the switch valve one, the desulfurization tower, the electrostatic precipitator, the shell side of the energy storage heat exchanger two, the shell side of the energy storage heat exchanger one, the denitrification tower, the pipe side of the energy storage heat exchanger three, the pipe side of the energy storage heat exchanger four, the buffer tank two, the switch valve two, the carbon capture device, the regenerator and the exhaust tower are connected in sequence to form a complete exhaust gas treatment flow path.

[0019] As a further improvement to the above solution, temperature sensors are provided at the tube inlet and outlet of all energy storage heat exchangers, and temperature sensors are also provided inside the energy storage medium of all energy storage heat exchangers; flow sensors are also provided in the tubes of all energy storage heat exchangers;

[0020] The sludge incineration tail gas treatment system also includes:

[0021] The controller is used to calculate the heat input on the hot side of each energy storage heat exchanger based on the monitoring data collected by the temperature sensor and flow sensor, and calculate the heat balance deviation value in combination with the target heat absorption of the energy storage medium, thereby formulating the following control strategy:

[0022] When the thermal balance deviation values of the energy storage heat exchanger 1 and the energy storage heat exchanger 2 each exceed a preset deviation threshold, the switch valve 1 is controlled to open;

[0023] When the thermal balance deviation values of the energy storage heat exchanger 3 and the energy storage heat exchanger 4 each exceed the deviation threshold, the switch valve 2 is controlled to open;

[0024] Among them, the heat input on the hot side of the energy storage heat exchanger is The calculation formula is:

[0025] ;

[0026] Where, is the mass flow rate of the heat medium in the tube, is the specific heat capacity of the heat medium, is the inlet and outlet temperature difference of the heat medium in the tube, For monitoring time;

[0027] Target heat absorption of energy storage medium The calculation formula is:

[0028] ;

[0029] Where, is the mass of the energy storage medium, is the phase change latent heat of the energy storage medium, is the specific heat capacity of the energy storage medium, The temperature difference required to achieve the target temperature;

[0030] Thermal balance deviation The calculation formula is:

[0031] .

[0032] As a further improvement of the above solution, in the air dehumidification heat pump module, the shell side inlet of the evaporator and the shell side outlet of the condenser are both provided with a temperature sensor and a humidity sensor; the shell side outlet of the energy storage heat exchanger 4 is provided with a temperature sensor;

[0033] The controller is also used to calculate the dehumidification capacity and dehumidification performance coefficient related to the air dehumidification heat pump module, thereby making the following control strategy:

[0034] When the temperature at the outlet of the fourth shell of the energy storage heat exchanger is lower than a preset temperature threshold, the blower speed is controlled to decrease to reduce the mass flow of air and prolong the residence time of air in the fourth shell of the energy storage heat exchanger, thereby improving the degree of air heating;

[0035] When the dehumidification capacity is less than a preset target dehumidification capacity, the operating frequency of the compressor is adjusted to increase the cooling output on the evaporator side;

[0036] When the dehumidification performance coefficient is lower than the preset performance evaluation threshold, the blower speed is controlled to decrease to reduce the mass flow of air, prolong the residence time of air in the evaporator, and thus improve the dehumidification degree; among them, the dehumidification capacity The calculation formula is:

[0037] ;

[0038] in, and are the absolute moisture content of the air at the evaporator shell inlet and the condenser shell outlet, respectively, in kg water / kg dry air;

[0039] Dehumidification-specific performance coefficient The calculation formula is:

[0040] ;

[0041] Where, is the mass flow rate of air, is the latent heat of condensation of water vapor, is the input power of the air dehumidification heat pump module.

[0042] As a further improvement of the above solution, in the exhaust gas purification module, a wet process is used for desulfurization treatment, and a selective catalytic reduction process is used for denitrification treatment.

[0043] The present invention also discloses an energy storage heat exchanger, which is applied to the above-mentioned sludge incineration exhaust gas treatment system; the energy storage heat exchanger includes a heat exchanger shell and an energy storage heat exchange tube; the energy storage heat exchange tube is a double-layer nested test tube structure, and the interlayer is filled with energy storage medium; the top end of the energy storage heat exchange tube is closed and the bottom end is open, and it is vertically installed on the bottom wall of the heat exchanger shell, thereby dividing the inner cavity of the heat exchanger shell into a shell side and a tube side.

[0044] As a further improvement of the above scheme, the energy storage heat exchanger further includes a central tube, an inlet pipe box and an outlet pipe box; the inlet pipe box, the outlet pipe box and the heat exchanger shell are adjacent to each other from bottom to top to form a tower structure; the bottom wall of the heat exchanger shell is provided with a first through hole connected to the outlet pipe box, and the first through hole is adapted to the size of the central circular hole at the bottom end of the energy storage heat exchange tube; the central tube is coaxially arranged with the energy storage heat exchange tube, the bottom end of the central tube is fixedly connected to the bottom wall of the outlet pipe box, the top end of the central tube extends into the energy storage heat exchange tube through the first through hole, and the top end of the central tube is connected to the energy storage heat exchange tube. There is a gap between the top ends of the inner walls of the tubes, and there is an annular gap radially between the outer wall of the central tube and the inner wall of the energy storage heat exchange tube, thereby forming a bent flow channel in the tube side of the energy storage heat exchanger; a second through hole connected to the inlet tube box is opened on the bottom wall of the outlet tube box, and the second through hole is adapted to the size of the central circular hole at the bottom end of the central tube; the inlet tube box and the outlet tube box are respectively provided with a tube side inlet and a tube side outlet on two opposite side walls; the heat exchanger shell is respectively provided with a shell side inlet and a shell side outlet on two opposite side walls, and the height of the shell side inlet is lower than the height of the shell side outlet.

[0045] As a further improvement of the above scheme, the energy storage heat exchanger is provided with a plurality of energy storage heat exchange tubes, which are distributed in an array on a horizontal plane; each energy storage heat exchange tube is also provided with a reinforcing rib in the interlayer; the outer surface of the central tube and the energy storage heat exchange tube are made of duplex stainless steel; wherein, the energy storage medium of energy storage heat exchanger 1 and energy storage heat exchanger 3 is the same, and the energy storage medium of energy storage heat exchanger 2 and energy storage heat exchanger 4 is the same, and the phase change temperature of the energy storage medium of the former two is higher than the phase change temperature of the energy storage medium of the latter two.

[0046] Compared with the prior art, the present invention has the following beneficial effects:

[0047] 1. The exhaust gas treatment system disclosed in this invention utilizes an energy storage heat exchanger as its core waste heat recovery unit. Through multi-stage heat exchange and dynamic energy management, it achieves efficient thermal energy storage and utilization within the high and low temperature ranges of incineration exhaust gas. The exhaust gas purification process sequentially includes particulate matter filtration, desulfurization, electrostatic precipitation, and denitrification, effectively removing particulate matter, acidic gases, and heavy metal pollutants. Waste heat is recovered through a circulating power generation module based on the Organic Rankine Cycle (ORC). This module utilizes a low-boiling-point working fluid to convert low-grade thermal energy into electricity, improving the overall energy efficiency of the system. The carbon capture and solidification module utilizes temperature swing adsorption (TSA) technology to separate CO2 and, combined with a low-temperature refrigeration process, liquefies and solidifies it into dry ice, promoting the high-value utilization of carbon resources. The air dehumidification heat pump module utilizes a heat pump cycle to dehumidify and heat the combustion air, reducing humidity, mitigating equipment corrosion, and improving combustion efficiency.

[0048] 2. The exhaust gas treatment system is equipped with four energy storage heat exchangers, and the two heat exchangers are differentiated to have the same heat exchange medium. This can not only accurately match the thermal energy characteristics of exhaust gases in different temperature zones, and realize efficient graded recovery and storage of heat energy from high temperature (about 160°C) to low temperature (about 80°C) during the incineration process, thereby improving the overall energy efficiency of the system, but also realize heat recovery between key desulfurization and denitrification links, and further utilize the waste heat generated by the denitrification process on the basis of the waste heat of the incineration exhaust gas itself, to achieve coordinated recovery, coupled utilization and dynamic regulation of multi-source heat energy, promote deep purification of exhaust gas and closed-loop utilization of energy, and significantly reduce energy consumption and carbon emissions.

[0049] 3. The exhaust gas treatment system disclosed in the present invention equips sensors at key positions of the tube side, shell side, energy storage medium and air dehumidification heat pump module of the heat exchanger, and designs an intelligent control strategy for the controller to realize an automatic adjustment mechanism. On the one hand, it automatically guides the exhaust gas to flow into the next module or realizes energy storage cycle control to avoid heat energy waste and ensure stable operation of the system; on the other hand, it realizes dual protection of the supply air temperature and humidity, ensuring that the air sent to the incinerator meets the optimal combustion conditions, further improving the heat pump operation efficiency and energy utilization rate of the entire system.

[0050] 4. The present invention provides an environmentally friendly, energy-saving and intelligent exhaust gas treatment solution, which is suitable for a variety of low-grade, high-humidity and high-pollution industrial exhaust scenarios and has broad engineering application prospects.

[0051] 5. The energy storage heat exchanger disclosed in the present invention, through innovative structural design, introduces a gravity sedimentation mechanism, effectively avoiding the pipe blockage problem common in traditional shell and tube heat exchangers, and realizes the self-cleaning function of the equipment, thereby greatly reducing maintenance frequency and improving operational stability and long-term reliability.

[0052] Traditional heat exchangers usually only have heat exchange functions and are unable to store and regulate energy, resulting in low efficiency in the utilization of low-grade thermal energy and serious energy waste. The energy storage heat exchanger of the present invention innovatively integrates a cascade energy storage function based on heat exchange. It can store and release thermal energy in a graded manner according to the grade of the heat source and heat demand, significantly improving the recovery and utilization efficiency of low-grade energy. This design effectively breaks the limitation of traditional heat exchangers of "instant heat exchange and inability to store heat", helps achieve balanced energy allocation and energy-saving optimization of system operation, and is in line with the development goals of energy conservation and carbon reduction.

[0053] In terms of material selection, traditional treatment of corrosive conditions involving highly polluting gases (such as those containing nitrides and sulfides) typically requires the use of expensive duplex stainless steel or bulky, complex-to-process fluoroplastic heat exchangers to address condensation corrosion. However, the present invention, based on the varying corrosion risks of various components, selects duplex stainless steel with excellent corrosion resistance for the hot side, effectively protecting against the corrosive condensing medium. Conventional alloy steel or carbon steel can be used for the non-hot side, reducing material costs and simplifying processing. This design significantly reduces manufacturing costs and equipment size while ensuring overall corrosion resistance and structural strength, resulting in greater economic efficiency, compactness, and engineering value. BRIEF DESCRIPTION OF THE DRAWINGS

[0054] Figure 1 This is a process architecture diagram of a sludge incineration tail gas treatment system in an embodiment of the present invention.

[0055] Figure 2 Schematic diagram of the structure of the energy storage heat exchanger in an embodiment of the present invention.

[0056] Figure 3 for Figure 2 Schematic diagram of the enlarged structure of the central energy storage heat exchange tube and central tube.

[0057] Figure 4 Schematic diagram of the medium flow in the tube side and shell side of the energy storage heat exchanger 1 in an embodiment of the present invention.

[0058] Figure 5 Schematic diagram of the medium flow in the tube side and shell side of the energy storage heat exchanger 2 in an embodiment of the present invention.

[0059] Figure 6 Schematic diagram of the medium flow in the tube side and shell side of the energy storage heat exchanger 3 in an embodiment of the present invention.

[0060] Figure 7 Schematic diagram of the medium flow direction of the tube side and shell side of the energy storage heat exchanger 4 in an embodiment of the present invention.

[0061] Figure: 1. Incinerator; 2. Bag filter; 3. Induced draft fan; 4. Energy storage heat exchanger 1; 5. Energy storage heat exchanger 2; 6. Desulfurization tower; 7. Electrostatic precipitator; 8. Denitrification tower; 9. Energy storage heat exchanger 3; 10. Energy storage heat exchanger 4; 11. Carbon capture device; 12. Refrigeration unit; 13. Liquid storage tank; 14. Freezer; 15. Steam turbine; 16. Generator; 17. Regenerator; 18. Exhaust tower; 19. Centrifugal pump; 20. Blower. 21. Compressor; 22. Evaporator; 23. Expansion valve; 24. Condenser; 25. Buffer tank 1; 26. On-off valve 1; 27. Buffer tank 2; 28. On-off valve 2; E1. Heat exchanger shell; E11. First through-hole; E2. Energy storage heat exchange tube; E20. Interlayer; E21. Reinforcement rib; E3. Center tube; E4. Inlet pipe box; E5. Outlet pipe box; E52. Second through-hole; E6. Annular gap; E7. Particulate matter discharge outlet. DETAILED DESCRIPTION

[0062] The following will clearly and completely describe the technical solutions in the embodiments of the present invention in conjunction with the accompanying drawings. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making creative efforts are within the scope of protection of the present invention.

[0063] See also Figures 1 to 3 This embodiment provides a sludge incineration tail gas treatment system, including: a tail gas purification module, a carbon capture and solidification module, a circulating power generation module, an air dehumidification heat pump module and a cascade energy storage module, and may also include a controller (not shown).

[0064] The exhaust gas purification module is used to sequentially filter particulate matter, desulfurize, remove electrostatic precipitators, and denitrify exhaust gas discharged from incinerator 1 at a temperature of 200°C to 250°C, removing particulate matter (PM), acidic gases (sulfur dioxide, nitrogen oxides), and heavy metal pollutants. The exhaust gas purification module includes a bag filter 2, a desulfurization tower 6, an electrostatic precipitator 7, and a denitrification tower 8, each performing particulate matter filtration, desulfurization, electrostatic precipitator, and denitrification treatments.

[0065] The sludge is sent to the incinerator 1 for high temperature combustion. The tail gas temperature is about 200-250℃. The tail gas contains particulate matter, SO2, NO x , CO2, heavy metals and other pollutants, the exhaust gas is transported to the bag filter 2 by the induced draft fan 3 and enters the subsequent purification and waste heat recovery link.

[0066] Among them, the bag filter 2 captures and filters particulate matter through high-efficiency filter materials, which can remove more than 90% of particulate matter in the exhaust gas. The exhaust gas after dust removal maintains a relatively high temperature and then enters the energy storage heat exchanger 4. The desulfurization tower 6 uses a typical wet desulfurization process (such as the limestone-gypsum method) for desulfurization treatment. The SO2 in the exhaust gas fully reacts with the alkaline components in the desulfurization liquid to generate calcium sulfite or calcium sulfate to achieve the purpose of desulfurization. At this time, the exhaust gas temperature is basically maintained above 80°C, which is suitable for subsequent electrostatic dust removal treatment. The denitrification tower 8 uses a selective catalytic reduction process for denitrification treatment. The exhaust gas is reheated to above 160°C and enters the denitrification tower 8. Under the action of the catalyst, it reacts with the reducing agent (such as ammonia or urea) to convert NO x It is reduced to harmless nitrogen (N2) and water, achieving deep purification of exhaust gas and ultra-low emissions.

[0067] The carbon capture and solidification module is used to collect CO2 from exhaust gas through temperature swing adsorption and cryogenic cooling technology, achieving efficient capture, liquefaction, and solidification of CO2. The module includes a carbon capture device 11, a refrigeration unit 12, a liquid storage tank 13, and a refrigerator 14. The carbon capture device 11 uses temperature swing adsorption technology to drive the adsorbent to selectively adsorb and desorb CO2 at different temperatures. The desorbed CO2 is then fed into the refrigeration unit 12 for liquefaction and storage in the liquid storage tank 13. The CO2 is then cooled to -78°C to -80°C through a cryogenic cooling process, converted into dry ice, and stored in the refrigerator 14. In some embodiments, the refrigeration unit 12 can use electricity provided by the circulating power generation module.

[0068] The circulating power generation module converts low-grade waste heat from exhaust gas into electricity using organic Rankine cycle technology. It comprises a steam turbine 15, a generator 16, a regenerator 17, an exhaust tower 18, and a centrifugal pump 19. The low-boiling-point working medium is heated to 150-160°C in the shell side of the energy storage heat exchanger 3 (9) and converted into high-pressure steam. This steam then enters the steam turbine 15, driving the turbine's impeller, which in turn drives the coupled generator 16 to generate electricity. After losing energy through work, the low-boiling-point working medium steam passes through the regenerator 17, where it exchanges waste heat with the cooled exhaust gas, which has collected CO2, to condense into a liquid state. The liquid is then transported back to the shell side of the energy storage heat exchanger 3 (9) by the centrifugal pump 19, and the exhaust gas is ultimately discharged through the exhaust tower 18. In this embodiment, the low-boiling-point working medium is R245fa (pentafluoropropane, boiling point approximately 15°C).

[0069] In this embodiment, the electricity generated by the circulating power generation module can be used to power various modules within the system, such as driving compressor 21, refrigeration unit 12, sensors, and controllers, forming a localized self-circulating energy cycle. After losing work energy, the R245fa vapor undergoes waste heat exchange with the cooled exhaust gas in regenerator 17, condensing it into a liquid state. The vapor is then transported back to energy storage heat exchanger 3 9 by centrifugal pump 19, forming a closed-loop thermal cycle system and enabling efficient reuse of low-grade waste heat.

[0070] The air dehumidification heat pump module is used to dehumidify and preheat the air entering the incinerator 1, improving combustion efficiency and reducing the moisture content of the exhaust gas. The air dehumidification heat pump module comprises a blower 20, a compressor 21, an evaporator 22, an expansion valve 23, and a condenser 24, all connected in sequence to form a refrigerant circulation system. The refrigerant passes through the expansion valve 23, the evaporator 22, the compressor 21, and the condenser 24 in a reverse Carnot cycle, exchanging heat with the fresh air supplied by the blower 20. The air is cooled in the evaporator 22 to a temperature between 0°C and 10°C, below the dew point, thereby dehumidifying the air. The air is then heated to a temperature between 30°C and 50°C in the condenser 24 for preheating. In this embodiment, the refrigerant used is R410A.

[0071] The cascaded energy storage module is used to recover and manage waste heat from different temperature zones in the exhaust gas during the purification process. It includes energy storage heat exchanger 1 (4), energy storage heat exchanger 2 (5), energy storage heat exchanger 3 (9), and energy storage heat exchanger 4 (10). It may also include buffer tank 1 (25), on / off valve 1 (26), buffer tank 2 (27), and on / off valve 2 (28).

[0072] The graded stored heat energy is allocated to the following functional modules for use: the energy storage heat exchanger three 9 provides a heat source for the circulating power generation module; the energy storage heat exchanger four 10 is used to provide heating support for the air dehumidification heat pump module.

[0073] Among them, the energy storage heat exchanger 1 4 is used to cool the exhaust gas after particulate matter filtration treatment to above the first temperature threshold and store high-grade waste heat; the energy storage heat exchanger 2 5 is used to cool the exhaust gas after energy storage heat exchanger 1 4 to above the second temperature threshold and store low-grade waste heat; the energy storage heat exchanger 1 4 and the energy storage heat exchanger 2 5 also use their own stored waste heat to gradually raise the exhaust gas after electrostatic dust removal and desulfurization to above the first temperature threshold for denitrification treatment, and the exhaust gas is heated after denitrification; the energy storage heat exchanger 3 9 is used to cool the exhaust gas after denitrification to above the first temperature threshold and store high-grade waste heat, and at the same time use the waste heat to convert the low-boiling point working fluid in the circulating power generation module from liquid to steam; the energy storage heat exchanger 4 10 is used to cool the exhaust gas after energy storage heat exchanger 3 9 to above the second temperature threshold and store low-grade waste heat, and at the same time use the waste heat to further heat the dehumidified and preheated air of the air dehumidification heat pump module to be sent to the incinerator 1.

[0074] Energy storage heat exchangers 1 (4) and 3 (9) use the same energy storage medium, while heat exchangers 2 (5) and 4 (10) use the same energy storage medium. The phase transition temperature of the energy storage medium in the former two is higher than that in the latter two. In this embodiment, heat exchangers 1 (4) and 3 (9) are filled with a NaNO₃-KNO₃ eutectic salt with a phase transition temperature of approximately 160°C, while heat exchangers 2 (5) and 4 (10) are filled with a paraffin-based energy storage material with a phase transition temperature of 80-100°C. This achieves the staged storage and release of high- and low-temperature thermal energy from the incineration exhaust gas.

[0075] Energy storage heat exchanger 1 4 , energy storage heat exchanger 2 5 , energy storage heat exchanger 3 9 and energy storage heat exchanger 4 10 all use the same energy storage heat exchanger, which includes a heat exchanger shell E1 and an energy storage heat exchange tube E2; the energy storage heat exchange tube E2 is a double-layer nested test tube structure (concentric hollow tube), and its interlayer E20 is filled with energy storage medium; the energy storage heat exchange tube E2 has a closed top and an open bottom, and is vertically installed on the bottom wall of the heat exchanger shell E1, thereby dividing the inner cavity of the heat exchanger shell E1 into a shell side and a tube side. The shell side is used to circulate a cold medium (a medium that needs to be heated), and the tube side is used to circulate a hot medium (a medium that needs to be cooled). The energy storage medium is used to absorb heat from the hot medium and release it to the cold medium.

[0076] The energy storage heat exchanger also includes a central tube E3, an inlet pipe box E4 and an outlet pipe box E5; the inlet pipe box E4, the outlet pipe box E5 and the heat exchanger shell E1 are adjacent to each other from bottom to top to form a tower structure; the bottom wall of the heat exchanger shell E1 is provided with a first through hole E11 connected to the outlet pipe box E5, and the first through hole E11 is adapted to the size of the central circular hole at the bottom end of the energy storage heat exchange tube E2; the central tube E3 is coaxially arranged with the energy storage heat exchange tube E2, the bottom end of the central tube E3 is fixedly connected to the bottom wall of the outlet pipe box E5, the top end of the central tube E3 extends into the energy storage heat exchange tube E2 through the first through hole E11, and there is a gap between the top end of the central tube E3 and the top end of the inner wall of the energy storage heat exchange tube E2 There is an annular gap E6 in the radial direction between the outer wall of the central tube E3 and the inner wall of the energy storage heat exchange tube E2, thereby forming a bent flow channel in the tube side of the energy storage heat exchanger; the bottom wall of the outlet pipe box E5 is provided with a second through hole E52 connected to the inlet pipe box E4, and the second through hole E52 is adapted to the size of the central circular hole at the bottom end of the central tube E3; the inlet pipe box E4 and the outlet pipe box E5 are respectively provided with a tube side inlet and a tube side outlet on two opposite side walls; the heat exchanger shell E1 is respectively provided with a shell side inlet and a shell side outlet on two opposite side walls, and the height of the shell side inlet can be lower than the height of the shell side outlet, so that the cold medium can fully contact the energy storage heat exchange tube E2 in the shell side. Figure 2 The tube side inlet, tube side outlet, shell side inlet and shell side outlet of the energy storage heat exchanger are also marked respectively.

[0077] The energy storage heat exchanger comprises several heat exchange tubes E2 arranged in a horizontal array. Each tube E2 also has reinforcing ribs E21 within its interlayer E20. The outer surfaces of the central tube E3 and the heat exchange tubes E2 are constructed of duplex stainless steel. The tubes can be arranged in an array at four angles: 30°, 60°, 45°, and 90°. These angles correspond to different arrangements: an equilateral triangle (30°), a corner equilateral triangle (60°), a square (45°), and a corner square (90°).

[0078] In this invention, the hot medium (including particles) flows through the tube side, while the cold medium flows through the shell side. The hot medium enters the inlet manifold E4 at the tube side inlet, then travels upward from the bottom of the central tube E3, making a return at the top gap. It then travels downward through the annular gap E6, entering the outlet manifold E5, and ultimately exits the heat exchanger through the tube side outlet. During this upward movement of the hot medium within the central tube E3, particles settle, which are then discharged through the particle discharge port at the bottom of the inlet manifold E5. The cold medium enters the shell side from the shell side inlet of the heat exchanger shell E1, passes through several energy storage heat exchange tubes E2, and is discharged through the shell side outlet on the other side of the heat exchanger shell E1, completing the heat exchange. The central tube E3 serves to settle particles, while the annular gap E6 improves heat exchange efficiency and prevents blockage. The energy storage medium within the interlayer absorbs and releases heat. This design effectively reduces the risk of blockage and enhances heat exchanger operation stability.

[0079] According to the transmission direction of the exhaust gas, the exhaust gas outlet of the incinerator 1, the bag filter 2, the induced draft fan 3, the tube side of the energy storage heat exchanger 14, the tube side of the energy storage heat exchanger 25, the buffer tank 1, the switch valve 1, the desulfurization tower 6, the electrostatic precipitator 7, the shell side of the energy storage heat exchanger 25, the shell side of the energy storage heat exchanger 14, the denitrification tower 8, the tube side of the energy storage heat exchanger 3, the tube side of the energy storage heat exchanger 4, the buffer tank 27, the switch valve 28, the carbon capture device 11, the regenerator 17 and the exhaust tower 18 are connected in sequence to form a complete exhaust gas treatment flow path. The specific process is as follows:

[0080] See also Figure 4 The tube-side inlet of the energy storage heat exchanger 1 4 is connected to the air outlet side of the induced draft fan 3, and is used to input the exhaust gas with a temperature of 200°C to 250°C that has been filtered through particulate matter. After heat exchange with the internal energy storage medium, the tube-side outlet of the energy storage heat exchanger 1 4 outputs the exhaust gas with a temperature higher than 160°C to the tube-side inlet of the energy storage heat exchanger 2 5.

[0081] See also Figure 5After the exhaust gas above 160°C is fed into the tube-side inlet of the energy storage heat exchanger 2 (5), it undergoes heat exchange with the internal energy storage medium. The tube-side outlet of the energy storage heat exchanger 5 then outputs exhaust gas above 80°C to the inlet of buffer tank 1 (25). This exhaust gas is temporarily stored within buffer tank 1 (25), and the interior of buffer tank 1 (25) is connected to the inlet of desulfurization tower 6 by controlling the opening and closing of on-off valve 1 (26). The outlet of desulfurization tower 6 is connected to the air inlet of electrostatic precipitator 7. After desulfurization and electrostatic precipitation, the temperature of the exhaust gas is lowered. The outlet of electrostatic precipitator 7 is connected to the shell-side inlet of energy storage heat exchanger 2 (5). The shell-side outlet of energy storage heat exchanger 2 (5) is connected to the shell-side inlet of energy storage heat exchanger 1 (4), and the shell-side outlet of energy storage heat exchanger 1 (4) is connected to the inlet of denitrification tower 8. The exhaust gas is reheated to above 160°C through the shell side of energy storage heat exchanger 2 5 and energy storage heat exchanger 1 4 before entering denitration tower 8 to complete selective catalytic reduction (SCR) denitration. This denitration process releases heat, raising the exhaust gas temperature. In some embodiments, by controlling factors such as the reaction rate of the denitration process, the exhaust gas entering energy storage heat exchanger 3 9 can be kept within a suitable temperature range (165°C-185°C) for subsequent recycling.

[0082] See also Figure 6 The tube-side inlet of the energy storage heat exchanger 3 (9) is connected to the outlet of the denitrification tower (8), exchanging heat with the heated exhaust gas after denitrification. The energy storage medium absorbs the residual heat, cooling the exhaust gas to above 160°C. The tube-side outlet of the energy storage heat exchanger 3 (9) is used to output heat to the tube-side inlet of the energy storage heat exchanger 4 (10). The shell-side inlet of the energy storage heat exchanger 3 (9) is connected to the outlet of the centrifugal pump (19). The residual heat absorbed by the energy storage medium evaporates the liquid R245fa into steam at 150°C to 160°C, which is then fed into the steam turbine (15) to generate electricity.

[0083] See also Figure 7 The tube-side inlet of the energy storage heat exchanger 10 receives exhaust gas at a temperature above 160°C, which is then exchanged with the energy storage medium. The tube-side outlet then outputs exhaust gas at a temperature above 80°C to the buffer tank 27, which temporarily stores this exhaust gas. The interior of the buffer tank 27 is connected to the carbon capture device 11 by controlling the opening and closing of the on-off valve 28. The shell-side inlet of the energy storage heat exchanger 10 receives dehumidified and preheated air from the air dehumidification heat pump module. The waste heat in the energy storage medium heats the air to approximately 80°C to 90°C before it is fed into the air inlet of the incinerator 1, improving combustion efficiency and reducing the moisture content of the exhaust gas.

[0084] In this embodiment, temperature sensors are provided at the tube inlet and outlet of all energy storage heat exchangers, and flow sensors are provided at the tube inlet or outlet of all energy storage heat exchangers for real-time monitoring of the heat exchange parameters on the hot side; temperature sensors are also provided inside the energy storage medium of all energy storage heat exchangers for real-time monitoring of the heat storage status.

[0085] The controller is used to calculate the heat input on the hot side of each energy storage heat exchanger based on the monitoring data collected by the temperature sensor and flow sensor, and calculate the heat balance deviation value in combination with the target heat absorption of the energy storage medium, thereby formulating the following control strategy:

[0086] When the thermal balance deviation values of the energy storage heat exchanger 1 4 and the energy storage heat exchanger 2 5 each exceed a preset deviation threshold (5%), the switch valve 1 26 is controlled to open;

[0087] When the thermal balance deviation values of the energy storage heat exchanger 3 9 and the energy storage heat exchanger 4 10 each exceed 5%, the switch valve 2 28 is controlled to open.

[0088] This control strategy can automatically guide the exhaust gas to flow into the next module or realize energy storage cycle control, avoiding heat energy waste and ensuring stable operation of the system.

[0089] Among them, the heat input on the hot side of the energy storage heat exchanger is The calculation formula is:

[0090] ;

[0091] Where, is the mass flow rate of the heat medium in the tube, is the specific heat capacity of the heat medium, is the inlet and outlet temperature difference of the heat medium in the tube, For monitoring time.

[0092] Target heat absorption of energy storage medium The calculation formula is:

[0093] ;

[0094] Where, is the mass of the energy storage medium, is the phase change latent heat of the energy storage medium, is the specific heat capacity of the energy storage medium, The temperature difference required to reach the target temperature (160°C or above 80°C);

[0095] Thermal balance deviation The calculation formula is:

[0096] .

[0097] In the air dehumidification heat pump module, the shell-side inlet of the evaporator 22 and the shell-side outlet of the condenser 24 are both provided with temperature sensors and humidity sensors; the shell-side outlet of the energy storage heat exchanger 10 is provided with a temperature sensor.

[0098] In order to improve the system's dehumidification capacity and energy efficiency, the controller is also used to calculate the dehumidification capacity and dehumidification performance coefficient associated with the air dehumidification heat pump module, thereby formulating the following control strategy:

[0099] When the temperature at the shell-side outlet of the energy storage heat exchanger 4 is lower than a preset temperature threshold (80°C), the speed of the blower 20 is reduced to reduce the air flow rate, thereby extending the residence time of the air in the shell-side of the energy storage heat exchanger 4, thereby increasing the degree of air heating and ensuring that the air sent to the incinerator meets the temperature requirements;

[0100] When dehumidification Less than a preset target dehumidification capacity When the temperature is high, the operating frequency of the compressor 21 is adjusted to increase the cooling output of the evaporator 22;

[0101] When the dehumidification performance coefficient is lower than the preset performance evaluation threshold, it indicates that the system dehumidification efficiency is low. At this time, the speed of the blower 20 is further controlled to decrease to reduce the mass flow of air and prolong the residence time of the air in the evaporator 22, thereby improving the dehumidification degree; the dehumidification performance coefficient The calculation formula is:

[0102] ;

[0103] Where, is the mass flow rate of air, is the latent heat of condensation of water vapor, is the input power of the air dehumidification heat pump module. It should be noted that when the blower speed is lowered by 20, the mass flow rate of the air However, the amount of moisture removed per unit air is more significant, which reduces the amount of latent heat removed. Overall increase, thus promote.

[0104] This control strategy achieves dual protection of supply air temperature and humidity, ensuring that the air sent to the incinerator meets optimal combustion conditions, while improving the heat pump operating efficiency and energy utilization of the entire system.

[0105] The above description is only a preferred specific embodiment of the present invention, but the scope of protection of the present invention is not limited thereto. Any technician familiar with the technical field, within the technical scope disclosed by the present invention, who makes equivalent replacements or changes based on the technical solution and inventive concept of the present invention, should be covered by the scope of protection of the present invention.

Claims

1. A sludge incineration tail gas treatment system, characterized in that: include: An exhaust gas purification module is used to sequentially perform particulate matter filtration, desulfurization, electrostatic dust removal and denitrification treatment on the exhaust gas discharged from the incinerator (1); Carbon capture and solidification module, used to collect CO2 from exhaust gas through temperature swing adsorption and cryogenic cooling technology; A cycle power generation module, which converts low-grade waste heat in tail gas into electricity through organic Rankine cycle technology; An air dehumidification heat pump module, used for dehumidifying and preheating the air entering the incinerator (1); A cascade energy storage module is used for hierarchically recovering and managing waste heat in different temperature zones in exhaust gas; the cascade energy storage module comprises an energy storage heat exchanger 1 (4), an energy storage heat exchanger 2 (5), an energy storage heat exchanger 3 (9) and an energy storage heat exchanger 4 (10); wherein, the energy storage heat exchanger 1 (4) is used to cool the exhaust gas after the particulate matter filtration treatment to above a first temperature threshold and store high-grade waste heat; the energy storage heat exchanger 2 (5) is used to cool the exhaust gas after the energy storage heat exchanger 1 (4) is cooled to above a second temperature threshold and store low-grade waste heat; the energy storage heat exchanger 1 (4) and the energy storage heat exchanger 2 (5) also use their own stored waste heat to Heat, the exhaust gas after electrostatic dust removal and desulfurization is gradually raised to above the first temperature threshold for denitrification treatment, and the exhaust gas is heated after denitrification; the energy storage heat exchanger three (9) is used to cool the exhaust gas after denitrification to above the first temperature threshold and store high-grade waste heat, and at the same time use the waste heat to convert the low-boiling-point working medium in the circulating power generation module from liquid to steam; the energy storage heat exchanger four (10) is used to cool the exhaust gas after the energy storage heat exchanger three (9) is cooled to above the second temperature threshold and store low-grade waste heat, and at the same time use the waste heat to further heat the air dehumidified by the air dehumidification heat pump module and preheated to be sent to the incinerator (1); Among them, all energy storage heat exchangers are internally provided with mutually independent shell side and tube side, the shell side is used for circulating cold medium, the tube side is used for circulating hot medium, and an energy storage medium for absorbing heat in the hot medium and releasing it to the cold medium is also provided between the shell side and the tube side; the energy storage medium is a phase change energy storage medium; the energy storage medium of energy storage heat exchanger 1 (4) and energy storage heat exchanger 3 (9) is the same, and the energy storage medium of energy storage heat exchanger 2 (5) and energy storage heat exchanger 4 (10) is the same, and the phase change temperature of the energy storage medium of the former two is higher than the phase change temperature of the energy storage medium of the latter two.

2. A sludge incineration tail gas treatment system according to claim 1, characterized in that: In the exhaust gas purification module, a wet process is used for desulfurization, and a selective catalytic reduction process is used for denitrification.

3. A sludge incineration tail gas treatment system according to claim 1 or 2, characterized in that: The energy storage heat exchanger comprises a heat exchanger shell (E1) and an energy storage heat exchange tube (E2); the energy storage heat exchange tube (E2) is a double-layer nested test tube structure, and its interlayer (E20) is filled with energy storage medium; the energy storage heat exchange tube (E2) is closed at the top and open at the bottom, and is vertically installed on the bottom wall of the heat exchanger shell (E1), thereby dividing the inner cavity of the heat exchanger shell (E1) into a shell side and a tube side.

4. A sludge incineration tail gas treatment system according to claim 3, characterized in that: The energy storage heat exchanger further comprises a central tube (E3), an inlet pipe box (E4) and an outlet pipe box (E5); the inlet pipe box (E4), the outlet pipe box (E5) and the heat exchanger shell (E1) are adjacent to each other from bottom to top to form a tower-like structure; the bottom wall of the heat exchanger shell (E1) is provided with a first through hole (E11) connected to the outlet pipe box (E5), and the first through hole (E11) is adapted to the size of the central circular hole at the bottom end of the energy storage heat exchange tube (E2); the central tube (E3) is coaxially arranged with the energy storage heat exchange tube (E2), the bottom end of the central tube (E3) is fixedly connected to the bottom wall of the outlet pipe box (E5), the top end of the central tube (E3) extends into the energy storage heat exchange tube (E2) through the first through hole (E11), and the central tube (E3) There is a gap between the top of the central tube (E3) and the top of the inner wall of the energy storage heat exchange tube (E2), and there is an annular gap (E6) in the radial direction between the outer wall of the central tube (E3) and the inner wall of the energy storage heat exchange tube (E2), thereby forming a bent flow channel in the tube side of the energy storage heat exchanger; the bottom wall of the outlet tube box (E5) is provided with a second through hole (E52) connected to the inlet tube box (E4), and the second through hole (E52) is adapted to the size of the central circular hole at the bottom end of the central tube (E3); the inlet tube box (E4) and the outlet tube box (E5) are respectively provided with a tube side inlet and a tube side outlet on two opposite side walls; the heat exchanger shell (E1) is respectively provided with a shell side inlet and a shell side outlet on two opposite side walls, and the height of the shell side inlet is lower than the height of the shell side outlet.

5. A sludge incineration tail gas treatment system according to claim 4, characterized in that: The energy storage heat exchanger is provided with a plurality of energy storage heat exchange tubes (E2) which are distributed in an array on a horizontal plane; a reinforcing rib (E21) is also provided in the interlayer (E20) of each energy storage heat exchange tube (E2); the outer surface of the central tube (E3) and the energy storage heat exchange tube (E2) are both made of duplex stainless steel; wherein, the energy storage medium of the energy storage heat exchanger 1 (4) and the energy storage heat exchanger 3 (9) is the same, and the energy storage medium of the energy storage heat exchanger 2 (5) and the energy storage heat exchanger 4 (10) is the same, and the phase change temperature of the energy storage medium of the former two is higher than the phase change temperature of the energy storage medium of the latter two.

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