A sludge drying system based on indirect heat extraction from waste power plant flue gas waste heat

Abstract

The utility model discloses a kind of sludge drying systems based on waste power plant flue gas waste heat indirect heat extraction formula, belong to waste heat utilization technical field, comprising: wall heat exchanger, the heat release side medium of wall heat exchanger is indirectly heated with flue gas, and heat source is provided for vacuum sludge evaporation equipment after through delivery channel. The present application recovers the waste heat in the flue gas of the waste power plant by indirect heat exchange with the wall heat exchanger, converting the waste heat that is directly discharged into a heat source for sludge drying. At the same time, the low-temperature evaporation process in the vacuum environment reduces the sensible heat and latent heat consumption of sludge drying. Combined with the medium closed-loop system, the overall energy consumption is lower than the traditional process, achieving efficient utilization of industrial waste heat and low carbon emission.

Description

Technical Field

[0001] This utility model belongs to the field of waste heat utilization technology, and in particular to a sludge drying system based on indirect heat extraction from waste gas from a waste-to-energy plant. Background Technology

[0002] With the acceleration of urbanization, the amount of sludge produced by wastewater treatment plants is increasing year by year, and sludge drying is a key link in volume reduction and resource utilization. However, traditional drying technologies rely on fossil fuels or electricity to provide heat sources, resulting in high energy consumption and large carbon emissions. At the same time, the flue gas from waste incineration power plants contains a large amount of waste heat (temperature typically 120-200℃), but existing waste heat recovery technologies are mostly used for power generation or heating, and are not fully adapted to the sludge drying scenario. Utility Model Content

[0003] Purpose of the utility model: To provide a sludge drying system based on indirect heat extraction from waste-to-energy flue gas, so as to solve the above-mentioned problems existing in the prior art.

[0004] Technical solution: A sludge drying system based on indirect heat extraction from waste-to-energy flue gas, comprising: a partition wall heat exchanger, wherein the heat-exhausting medium of the partition wall heat exchanger indirectly extracts heat from the flue gas and then provides a heat source for vacuum sludge evaporation equipment through a conveying channel.

[0005] Furthermore, the indirect heat exchanger is provided with a flue gas inlet and a flue gas outlet.

[0006] Furthermore, the flue gas inlet is the flue gas inlet of the waste-to-energy plant, and the flue gas outlet is the flue gas outlet of the waste-to-energy plant.

[0007] Furthermore, the vacuum sludge evaporation equipment releases heat, and the heat-releasing medium is transported to the indirect heat exchanger through the return liquid channel.

[0008] Furthermore, a circulation pump is provided on the return channel or the delivery channel.

[0009] Furthermore, the sludge vapor generated by the vacuum sludge evaporation equipment is connected to the condenser through the vapor channel.

[0010] Furthermore, the vacuum sludge evaporation equipment is a jacketed sludge drying box.

[0011] Furthermore, the vacuum sludge evaporation equipment is a vacuum disc sludge dryer.

[0012] Furthermore, it also includes a vacuum pump, which is connected to the condenser via a pipeline to establish a vacuum environment inside the vacuum sludge evaporation equipment.

[0013] Furthermore, the condenser is provided with a cooling water inlet and a cooling water outlet.

[0014] Furthermore, the condenser is provided with a sludge condensate outlet.

[0015] Furthermore, a dust removal device is installed on the exhaust steam passage.

[0016] Furthermore, a heat replenishment device is provided on the conveying channel.

[0017] Beneficial effects:

[0018] This application employs a partitioned heat exchanger to recover waste heat from the flue gas of a waste-to-energy plant through indirect heat exchange, converting the originally directly emitted waste heat into a heat source for sludge drying. Simultaneously, the low-temperature evaporation process under vacuum reduces the sensible and latent heat consumption during sludge drying. Combined with a closed-loop media circulation system, the overall energy consumption is lower than traditional processes, achieving efficient utilization of industrial waste heat and low carbon emissions. Attached Figure Description

[0019] Figure 1 This is a system diagram of this utility model.

[0020] The attached diagram is labeled as follows: 100 for indirect heat exchanger, 110 for flue gas inlet, 120 for flue gas outlet, 200 for conveying channel, 300 for vacuum sludge evaporation equipment, 400 for return liquid channel, 500 for circulating pump, 600 for exhaust steam channel, 700 for condenser, 710 for cooling water inlet, 720 for cooling water outlet, 730 for sludge condensate outlet, 800 for vacuum pump, 900 for heat replenishment device, and 1000 for dust removal device. Detailed Implementation

[0021] In the following description, numerous specific details are set forth in order to provide a more thorough understanding of the present invention. However, it will be apparent to those skilled in the art that the present invention can be practiced without one or more of these details. In other instances, certain technical features well-known in the art have not been described in order to avoid confusion with the present invention.

[0022] Combined with appendix Figure 1Description: A sludge drying system based on indirect heat extraction from waste-to-energy flue gas includes: a partition wall heat exchanger 100, wherein the heat-releasing medium of the partition wall heat exchanger 100 indirectly extracts heat from the flue gas and then provides a heat source to a vacuum sludge evaporation device 300 via a conveying channel 200. The partition wall heat exchanger 100 is provided with a flue gas inlet 110 and a flue gas outlet 120. The flue gas inlet 110 is the flue gas inlet of the waste-to-energy plant, and the flue gas outlet 120 is the flue gas outlet of the waste-to-energy plant. The vacuum sludge evaporation device 300, after releasing heat, conveys the heat-releasing medium to the partition wall heat exchanger 100 via a return liquid channel 400. A circulation pump 500 is provided on the return liquid channel 400 or the conveying channel 200. The sludge exhaust steam generated by the vacuum sludge evaporation device 300 is connected to a condenser 700 via an exhaust steam channel 600. The vacuum sludge evaporation device 300 is a jacketed sludge drying box. The vacuum sludge evaporation equipment 300 is a vacuum disc sludge dryer. It also includes a vacuum pump 800, which is connected to a condenser 700 via pipeline to establish a vacuum environment inside the vacuum sludge evaporation equipment 300. The condenser 700 is equipped with a cooling water inlet 710 and a cooling water outlet 720. The condenser 700 is also equipped with a sludge condensate outlet 730. A dust removal device 1000 is installed on the exhaust steam passage 600. A heat exchange device 900 is installed on the conveying passage 200.

[0023] When the vacuum sludge evaporation equipment 300 is a jacketed sludge drying box, its structure mainly includes an evaporation chamber and a heat source chamber that surrounds the evaporation chamber. The heat source chamber is connected to the partition heat exchanger 100 through the return liquid channel 400 and the conveying channel 200, and the power circulation is achieved through the circulation pump 500. Sludge is placed in the evaporation chamber and flash evaporation is carried out in a negative pressure environment. The heat source chamber continuously provides heat to complete the sludge drying.

[0024] The indirect heat exchanger 100, as the core heat exchange unit of the system, has its flue gas inlet 110 connected to the flue gas duct of the waste-to-energy plant. After entering through the inlet, the high-temperature flue gas undergoes indirect heat exchange with the heat-exhausting medium through the heat exchange wall. Heat is transferred to the medium side via the wall, and the cooled flue gas is discharged from the flue gas outlet 120. This indirect structure avoids direct contact between the flue gas and the medium, preventing dust and acidic substances in the flue gas from contaminating the medium or corroding the equipment. Simultaneously, it improves heat exchange efficiency by increasing the heat exchange area, such as through finned tube design. The heated heat-exhausting medium is then supplied to the vacuum sludge evaporation equipment 300 via the conveying channel 200, realizing the secondary utilization of industrial waste heat and reducing the energy consumption cost of sludge drying.

[0025] The conveying channel 200 adopts an insulated pipeline design, internally conveying the high-temperature medium heated by the partition heat exchanger 100, providing a stable heat source for the heat source chamber of the vacuum sludge evaporation equipment 300. The supplementary heating device 900 installed on the pipeline can automatically start when the waste heat of the flue gas is insufficient, to compensate for heat fluctuations and ensure the continuity of the drying process. The supplementary heating device 900 can be a heating device or a supplementary heating pipeline, and the heating device can be electric heating or other heat exchange methods.

[0026] Vacuum sludge evaporation equipment 300 has differentiated advantages depending on its type:

[0027] Jacketed sludge drying box: It adopts a double-layer structure of "evaporation chamber + heat source chamber". The heat source chamber receives high-temperature medium through the conveying channel 200, and the heat is conducted to the sludge in the evaporation chamber through the jacket wall. The negative pressure environment is maintained by the vacuum pump 800, which allows the moisture in the sludge to quickly flash evaporate into exhaust steam at low temperature, avoiding the damage of organic matter in the sludge by high temperature and reducing energy consumption. The jacket structure increases the heat exchange area, improving the sludge drying rate by more than 30%.

[0028] Vacuum disc sludge dryer: The rotating disc agitator evenly distributes the sludge on the heat source surface. Combined with negative pressure evaporation, it further improves the drying efficiency and uniformity. It is suitable for the treatment of high-viscosity sludge. The dried sludge has uniform particle size, which is convenient for subsequent disposal.

[0029] The return liquid channel 400 and the conveying channel 200 together form a medium circulation loop, which transports the medium that has released heat in the heat source chamber of the vacuum sludge evaporation equipment 300 back to the partition wall heat exchanger 100 for reheating. The circulation pump 500 on the channel provides power to overcome pipeline resistance and ensure that the medium circulates at a constant flow rate, avoiding heat transfer lag caused by natural convection and improving the system's thermal efficiency.

[0030] The exhaust steam channel 600 is responsible for conveying the exhaust steam and a small amount of volatile organic compounds generated by the vacuum sludge evaporation equipment 300 to the condenser 700. A dust removal device 1000 installed on the channel, such as a bag filter or cyclone separator, can filter sludge particles with a diameter ≥5μm carried in the exhaust steam with a removal rate of up to 99%, preventing impurities from clogging the condenser pipes or affecting the condensation effect. For example, for sludge with a high sand content, the dust removal device can effectively reduce the subsequent condensate treatment load and improve the system's operational stability.

[0031] The condenser 700 introduces cooling water, such as circulating water or groundwater, through the cooling water inlet 710 to exchange heat with the exhaust steam, condensing the water vapor into liquid water. The condensed sludge condensate is discharged from the sludge condensate outlet 730 and can be further treated for reuse or discharged in compliance with standards. The cooling water absorbs heat and is discharged from the cooling water outlet 720 or connected to the cooling system. At the same time, it maintains the negative pressure environment inside the vacuum sludge evaporation equipment 300 to ensure that the drying process continues.

[0032] Vacuum pump 800 is connected to condenser 700 via pipeline, continuously extracting air from the system to maintain the internal pressure of vacuum sludge evaporation equipment 300, creating a high vacuum environment. This design lowers the boiling point of water, significantly reducing drying energy consumption, while also suppressing the volatilization of malodorous gases such as ammonia and hydrogen sulfide in the sludge, reducing odor concentration in the working environment and improving operating conditions.

[0033] The heat replenishment device 900 serves as an emergency heat replenishment unit for the system. When the heat provided by the indirect heat exchanger 100 is insufficient, such as when the flue gas temperature is lower than the design value or when the heat is insufficient, the medium in the conveying channel 200 is heated again by means of electric heating or steam heating to ensure that the heat source temperature of the vacuum sludge evaporation equipment 300 is stable within the design range or directly switched to other heat sources.

[0034] The dust removal device 1000 is installed on the exhaust steam passage 600. It adopts a multi-stage filtration design, such as a pre-coarse filter screen and a post-high-efficiency filter element, which can effectively remove sludge, debris, dust and other impurities in the exhaust steam. This prevents impurities from entering the condenser 700, which could lead to a decrease in heat exchange efficiency or pipe blockage, extend the cleaning cycle of the condenser and reduce maintenance costs.

[0035] Work process:

[0036] 1. Flue gas waste heat recovery and medium heating

[0037] High-temperature flue gas from the waste-to-energy plant enters through the flue gas inlet 110 of the indirect heat exchanger 100, where it indirectly exchanges heat with the heat-exerting medium via indirect walls such as heat exchange tubes. The heat from the flue gas is transferred to the medium through the walls, and the gas, after its temperature decreases, is discharged from the flue gas outlet 120. The heated medium is then output through the conveying channel 200, providing a heat source for subsequent sludge drying. This process achieves efficient recovery of waste heat from the flue gas, avoiding direct heat emission and waste.

[0038] 2. Sludge drying under vacuum conditions

[0039] The heated medium enters the heat source chamber of the jacketed sludge drying box or vacuum disc sludge dryer in the vacuum sludge evaporation equipment 300 through the conveying channel 200. Under the action of the vacuum pump 800, the inside of the equipment is connected to the condenser 700 through pipelines to form a negative pressure environment.

[0040] Jacketed drying chamber: The high-temperature medium in the heat source chamber conducts heat to the sludge in the evaporation chamber through the jacket wall. The water in the sludge flashes at low temperature under negative pressure into exhaust steam and a small amount of volatile substances.

[0041] Vacuum disc dryer: The rotating disc agitator causes the sludge to come into uniform contact with the heat source surface, and the negative pressure environment accelerates the evaporation of moisture, forming exhaust steam.

[0042] During this process, the negative pressure environment lowers the boiling point of water, reduces energy consumption, and inhibits the volatilization of malodorous gases.

[0043] 3. Medium circulation and heat replenishment

[0044] After releasing heat, the medium flows back to the indirect heat exchanger 100 through the return liquid channel 400. Powered by the circulation pump 500, it overcomes pipeline resistance and ensures continuous circulation of the medium between the conveying channel 200 and the return liquid channel 400. If the waste heat of the flue gas is insufficient, the supplementary heating device 900 on the conveying channel 200, such as an electric heating element, will automatically start to provide auxiliary heating to the medium and maintain the stability of the heat source required for drying.

[0045] 4. Waste steam treatment and condensate recovery

[0046] The exhaust steam generated during sludge drying first passes through a dust removal device 1000 via exhaust steam channel 600, filtering out sludge particles, dust, and other impurities carried in the exhaust steam to prevent clogging of subsequent equipment. The purified exhaust steam then enters the condenser 700, where it exchanges heat with cooling water flowing in from the cooling water inlet 710. The water vapor in the exhaust steam is condensed into liquid water, which is discharged from the sludge condensate outlet 730 for further treatment and reuse or discharge. The cooling water absorbs heat and flows back to the cooling system from the cooling water outlet 720. The condensation process also helps maintain the negative pressure environment within the vacuum sludge evaporation equipment 300, ensuring continuous drying.

[0047] 5. System coordination and energy closed loop

[0048] The entire process utilizes a partitioned heat exchanger 100 for waste heat recovery, a vacuum sludge evaporation device 300 for low-temperature drying, a condenser 700 and a vacuum pump 800 to maintain negative pressure circulation, and a circulating pump 500 to drive the flow of the medium, forming a closed-loop system of "waste heat recovery - drying - medium circulation - exhaust steam treatment". The coordinated action of these components achieves efficient utilization of waste heat from the waste-to-energy plant's flue gas and energy-saving, clean drying of the sludge, while simultaneously reducing energy consumption and pollutant emissions.

[0049] The preferred embodiments of the present invention have been described in detail above with reference to the accompanying drawings. However, the present invention is not limited to the specific details of the above embodiments. Within the scope of the technical concept of the present invention, various equivalent transformations can be made to the technical solutions of the present invention, and all such equivalent transformations fall within the protection scope of the present invention.

Claims

1. A sludge drying system based on indirect heat extraction from waste-to-energy flue gas, characterized in that, include: A partition wall heat exchanger (100) is used to indirectly heat the heat-exhausting medium on the heat-exhausting side of the heat exchanger (100) and the flue gas, and then provides a heat source to the vacuum sludge evaporation equipment (300) through the conveying channel (200). The vacuum sludge evaporation equipment (300) is a jacketed sludge drying box or a vacuum disc sludge dryer.

2. The sludge drying system based on indirect heat extraction from waste-to-energy flue gas as described in claim 1, characterized in that, The indirect heat exchanger (100) is provided with a flue gas inlet (110) and a flue gas outlet (120).

3. The sludge drying system based on indirect heat extraction from waste-to-energy flue gas as described in claim 2, characterized in that, The flue gas inlet (110) is the flue gas inlet of the waste-to-energy plant, and the flue gas outlet (120) is the flue gas outlet of the waste-to-energy plant.

4. The sludge drying system based on indirect heat extraction from waste-to-energy flue gas as described in claim 1, characterized in that, The vacuum sludge evaporation equipment (300) delivers the heat-releasing medium to the indirect heat exchanger (100) through the return liquid channel (400) after releasing heat.

5. The sludge drying system based on indirect heat extraction from waste-to-energy flue gas as described in claim 4, characterized in that, A circulation pump (500) is provided on the return channel (400) or the delivery channel (200).

6. The sludge drying system based on indirect heat extraction from waste-to-energy flue gas as described in claim 1, characterized in that, The sludge vapor generated by the vacuum sludge evaporation equipment (300) is connected to the condenser (700) through the vapor channel (600).

7. The sludge drying system based on indirect heat extraction from waste-to-energy flue gas as described in claim 6, characterized in that, It also includes a vacuum pump (800), which is connected to the condenser (700) via a pipeline and is used to establish a vacuum environment inside the vacuum sludge evaporation equipment (300).

8. The sludge drying system based on indirect heat extraction from waste-to-energy flue gas as described in claim 6, characterized in that, The condenser (700) is provided with a cooling water inlet (710) and a cooling water outlet (720).

9. The sludge drying system based on indirect heat extraction from waste-to-energy flue gas as described in claim 6, characterized in that, The condenser (700) is provided with a sludge condensate outlet (730).

10. The sludge drying system based on indirect heat extraction from waste-to-energy flue gas as described in claim 6, characterized in that, A dust removal device (1000) is installed on the exhaust steam passage (600).

11. The sludge drying system based on indirect heat extraction from waste-to-energy flue gas as described in claim 1, characterized in that, A heating device (900) is provided on the conveying channel (200).

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