Low-temperature flue gas treatment system

Abstract

The utility model relates to the field of hazardous waste incineration disposal, in particular to a low-temperature flue gas treatment system which comprises a heat exchange element, a secondary combustion chamber, a waste heat utilization element and a flue gas purification element. The heat exchange element comprises a first medium channel and a second medium channel; an inlet of the first medium channel is connected with low-temperature flue gas to be treated, an outlet of the first medium channel is connected with an inlet of the secondary combustion chamber, and an outlet of the secondary combustion chamber is connected with an inlet of the waste heat utilization element; an outlet of the waste heat utilization element is connected with an inlet of the second medium channel, and an outlet of the second medium channel is connected with the flue gas purification element. Preheating of low-temperature flue gas can be achieved, meanwhile, waste heat recovery of high-temperature flue gas can be achieved, and energy conservation and consumption reduction are achieved.

Description

Technical Field

[0001] This utility model relates to the field of hazardous waste incineration and disposal, specifically to a low-temperature flue gas treatment system. Background Technology

[0002] In the field of hazardous waste incineration, national standards require the installation of a secondary combustion chamber for flue gas, which must heat the exhaust gas generated by the incineration unit to above 1100°C. Heating low-temperature flue gas to above 1100°C requires the input of a large amount of fuel into the secondary combustion chamber, increasing the user's energy consumption and disposal costs.

[0003] Preheating low-temperature flue gas with high-temperature flue gas to raise its temperature before it enters the secondary combustion chamber is one way to reduce energy consumption and disposal costs. However, due to limitations in materials and structure, it is still not possible to directly exchange heat between high-temperature flue gas (above 1100℃) and low-temperature flue gas. Utility Model Content

[0004] The purpose of this invention is to provide a low-temperature flue gas treatment system that can preheat low-temperature flue gas and recover waste heat from high-temperature flue gas, thereby saving energy and reducing consumption.

[0005] To achieve the above objectives, the technical solution adopted by this utility model is as follows:

[0006] A low-temperature flue gas treatment system includes a heat exchange element, a secondary combustion chamber, a waste heat utilization element, and a flue gas purification element. The heat exchange element includes a first medium channel and a second medium channel. The inlet of the first medium channel is connected to the low-temperature flue gas to be treated, the outlet of the first medium channel is connected to the inlet of the secondary combustion chamber, and the outlet of the secondary combustion chamber is connected to the inlet of the waste heat utilization element. The outlet of the waste heat utilization element is connected to the inlet of the second medium channel, and the outlet of the second medium channel is connected to the flue gas purification element.

[0007] Furthermore, the temperature of the low-temperature flue gas to be treated is <300℃.

[0008] Furthermore, the temperature of the high-temperature flue gas discharged from the outlet of the secondary combustion chamber is >1100℃.

[0009] Furthermore, the temperature of the medium-temperature flue gas discharged from the outlet of the waste heat utilization element is 600~800℃.

[0010] Furthermore, the temperature of the low-temperature flue gas discharged from the outlet of the second medium channel is 500~550℃.

[0011] Furthermore, the waste heat utilization element is a waste heat boiler, which uses the heat from the flue gas discharged from the secondary combustion chamber to heat water and generate saturated steam.

[0012] Furthermore, the waste heat utilization element is a heat exchanger.

[0013] This invention offers the following unexpected advantages: Low-temperature flue gas is introduced into the first medium channel of the heat exchanger, while medium-temperature flue gas, cooled by a waste heat recovery element, is introduced into the second medium channel. The medium-temperature flue gas preheats the low-temperature flue gas in the first medium channel, increasing the temperature of the exhaust gas entering the secondary combustion chamber, thereby reducing fuel consumption and achieving energy conservation. Furthermore, the high-temperature flue gas discharged from the secondary combustion chamber is first recovered through the waste heat recovery element before being introduced into the second medium channel for heat exchange, solving the technical problem that high-temperature flue gas cannot directly exchange heat with low-temperature flue gas. Attached Figure Description

[0014] Figure 1 A schematic diagram of the low-temperature flue gas treatment system according to an embodiment of the present invention is shown.

[0015] In the diagram, 1—heat exchange element, 2—secondary combustion chamber, 3—waste heat utilization element, and 4—flue gas purification element. Detailed Implementation

[0016] The embodiments of this utility model will be described below with reference to the accompanying drawings and preferred embodiments. Those skilled in the art can easily understand other advantages and effects of this utility model from the content disclosed in this specification. This utility model can also be implemented or applied through other different specific embodiments, and various details in this specification can also be modified or changed based on different viewpoints and applications without departing from the spirit of this utility model. It should be understood that the preferred embodiments are only for illustrating this utility model and not for limiting the scope of protection of this utility model.

[0017] It should be noted that the illustrations provided in the following embodiments are only schematic representations of the basic concept of the present invention. Therefore, the drawings only show the components related to the present invention and are not drawn according to the number, shape and size of the components in actual implementation. In actual implementation, the form, quantity and proportion of each component can be arbitrarily changed, and the layout of the components may also be more complex.

[0018] In one embodiment, see Figure 1 As shown, this utility model provides a low-temperature flue gas treatment system, including a heat exchange element 1, a secondary combustion chamber 2, a waste heat utilization element 3, and a flue gas purification element 4. The heat exchange element 1 includes a first medium channel and a second medium channel; the inlet a of the first medium channel is connected to the low-temperature flue gas to be treated, the outlet b of the first medium channel is connected to the inlet c of the secondary combustion chamber 2, and the outlet d of the secondary combustion chamber 2 is connected to the inlet e of the waste heat utilization element 3; the outlet f of the waste heat utilization element 3 is connected to the inlet g of the second medium channel, and the outlet h of the second medium channel is connected to the flue gas purification element 4.

[0019] The first and second medium channels of the heat exchange element 1 are crucial for heat exchange and energy transfer. They are typically made of materials with good thermal conductivity, such as stainless steel or copper alloys, to ensure efficient heat conduction. The interior of the channels employs a finned tube structure to increase the heat exchange area and improve heat exchange efficiency. The fins can be circular or rectangular in shape and are evenly distributed on the inner wall of the pipe, increasing the contact area between the exhaust gas and the pipe wall, thereby accelerating heat transfer.

[0020] The first medium channel inlet a is connected to the low-temperature flue gas to be treated, which comes from the incineration device. For example, the temperature of the low-temperature flue gas to be treated is <300°C, and its composition is complex, containing various pollutants such as particulate matter, carbon monoxide, volatile organic compounds (VOCs), sulfur dioxide, nitrogen oxides, dioxins and other harmful substances.

[0021] The outlet b of the first medium channel is connected to the inlet c of the second combustion chamber. When the low-temperature flue gas to be treated enters the first medium channel, it will flow along the pipe. During this process, it will exchange heat with the pipe wall and absorb some of the heat from the medium-temperature flue gas in the second medium channel, thus increasing its own temperature and providing a certain energy basis for the subsequent treatment in the second combustion chamber 2. This reduces the fuel consumption of the second combustion chamber and achieves the purpose of energy saving.

[0022] The primary function of the secondary combustion chamber 2 is to further oxidize and decompose the combustible components in the exhaust gas, which has been heated by the heat exchange element 1, through combustion. The secondary combustion chamber 2 is equipped with a burner and can use natural gas, propane, or other auxiliary fuels to ensure the stability and completeness of the combustion process. When the exhaust gas from the first medium channel enters the secondary combustion chamber 2, under high temperature (typically 850°C to 1100°C) and with a sufficient oxygen supply, the combustible components are completely burned, converting into harmless substances such as carbon dioxide and water.

[0023] The secondary combustion chamber 2 is also equipped with temperature and pressure sensors to monitor the temperature and pressure inside the combustion chamber in real time, ensuring that the combustion process takes place within a safe and efficient range. Simultaneously, by adjusting the fuel supply and air intake, the combustion temperature and completeness can be precisely controlled.

[0024] The outlet d of the secondary combustion chamber 2 is connected to the inlet e of the waste heat utilization element 3. The high-temperature flue gas (temperature > 1100℃) after being processed by the secondary combustion chamber 2 carries a large amount of heat energy, which will be transported to the waste heat utilization element for energy recovery.

[0025] The waste heat utilization element 3 can take various forms, commonly including waste heat boilers or heat exchangers. If a waste heat boiler is used, it can convert the thermal energy of high-temperature gas into saturated steam, which can then be used for other production processes in the factory, such as heating, power generation, or driving steam turbines.

[0026] If a heat exchanger is used, it can transfer the heat of high-temperature gas to other media, such as hot water, to provide heat for the hot water supply system in the plant area and improve the overall utilization rate of energy.

[0027] The waste heat utilization element 3 includes multiple tube bundles or plates, with a certain spacing between them to ensure smooth gas flow and sufficient heat exchange.

[0028] The outlet f of the waste heat recovery element 3 is connected to the inlet g of the second medium channel. After heat recovery, the temperature of the gas will be significantly reduced, but it still has a certain amount of thermal energy. At this time, it will enter the second medium channel of the heat exchange element 1 for further processing. For example, the temperature of the medium-temperature flue gas discharged from the outlet f of the waste heat recovery element is 600~800℃. After the medium-temperature flue gas is processed by the heat exchange element 1, the temperature of the low-temperature flue gas discharged from the outlet h of the second medium channel is 500~550℃.

[0029] The flue gas purification element 4 is the final checkpoint to ensure that the exhaust gas meets emission standards. Its main purpose is to remove pollutants remaining in the exhaust gas after the previous treatment steps. For example, the flue gas purification element 4 includes various purification devices, such as a bag filter to effectively remove particulate matter from the exhaust gas. Fine dust particles are intercepted on the surface of the filter bag through filtration, achieving a purification effect. It may also include an activated carbon adsorption device for adsorbing residual volatile organic compounds. Furthermore, it can be equipped with desulfurization and denitrification devices to further treat sulfur dioxide and nitrogen oxides, ensuring that their emission concentrations meet national and local environmental protection standards.

[0030] The flue gas purification element 4 may also include a wet scrubbing tower, which dissolves or neutralizes pollutants such as acidic gases in the exhaust gas by spraying chemical agents or water, thereby achieving the purpose of purification.

[0031] The outlet h of the second medium channel is connected to the flue gas purification element 4. The gas treated by the flue gas purification element 4 finally achieves compliant emission, and the temperature and pollutant concentration of the emitted gas meet relevant national standards, such as particulate matter concentration below 30 mg / m³. 3 Sulfur dioxide concentration below 50 mg / m³ 3 Nitrogen oxide concentration below 200 mg / m³ 3 Volatile organic compound concentration below 120 mg / m³ 3 .

[0032] The following analysis and explanation will be based on specific examples.

[0033] The low-temperature flue gas emitted from the hazardous waste incineration unit has a temperature of 220℃ and a flow rate of 15000 Nm³. 3 / h. If this low-temperature flue gas is directly heated to 1100℃ by natural gas combustion in the secondary combustion chamber, the theoretical natural gas consumption is approximately 1270 Nm³. 3 / h.

[0034] like Figure 1 As shown, the low-temperature flue gas treatment system of this invention introduces a waste heat boiler (wasting element 3) into the waste heat utilization element 3. The waste heat boiler generates saturated steam with a flow rate of 5.67 t / h and a pressure of 1.0 MPa, thus cooling the high-temperature flue gas from the secondary combustion chamber 2 to a medium-temperature flue gas of 700°C. This medium-temperature flue gas is then cooled to a low-temperature flue gas of 500°C by the heat exchange element 1 before entering the subsequent process, the flue gas purification element 4. The low-temperature flue gas, initially at 220°C, is heated to 535°C by the medium-temperature flue gas in the heat exchange element 1 before being introduced into the secondary combustion chamber 2 and heated to 1100°C. Through this method, the theoretical natural gas consumption of the secondary combustion chamber 2 is approximately 810 Nm³. 3 Compared to directly heating the low-temperature flue gas to be treated at a temperature of 220℃, the per-hour efficiency saves 36% of natural gas, greatly reducing operating costs and energy consumption, and increasing the company's profits.

[0035] The above embodiments are merely preferred embodiments provided to fully illustrate the present utility model, and the protection scope of the present utility model is not limited thereto. Equivalent substitutions or modifications made by those skilled in the art based on the present utility model are all within the protection scope of the present utility model.

Claims

1. A low temperature flue gas treatment system, characterized by: It comprises heat exchange element (1), two combustion chambers (2), waste heat utilization element (3) and flue gas purification element (4); the heat exchange element (1) comprises first medium channel and second medium channel; The first medium channel entrance a is connected with the low-temperature flue gas to be treated, the first medium channel exit b is connected with the entrance c of the two combustion chambers (2), the exit d of the two combustion chambers (2) is connected with the entrance e of the waste heat utilization element (3); The exit f of the waste heat utilization element (3) is connected with the entrance g of the second medium channel, and the exit h of the second medium channel is connected with the flue gas purification element (4).

2. The low temperature smoke treatment system of claim 1, wherein: The temperature of the low-temperature flue gas to be treated is less than 300 DEG C.

3. The low temperature smoke treatment system of claim 1, wherein: The temperature of the high-temperature flue gas discharged from the exit d of the two combustion chambers (2) is more than 1100 DEG C.

4. The low temperature flue gas treatment system of claim 1, wherein: The temperature of the medium-temperature flue gas discharged from the exit f of the waste heat utilization element (3) is 600-800 DEG C.

5. The low temperature flue gas treatment system of claim 1, wherein: The temperature of the low-temperature flue gas discharged from the exit h of the second medium channel is 500-550 DEG C.

6. The low temperature smoke treatment system of claim 1, wherein: The waste heat utilization element (3) is a waste heat boiler, which uses the heat of the flue gas discharged from the two combustion chambers to heat water and generate saturated steam.

7. The low temperature flue gas treatment system of claim 1, wherein: The waste heat utilization element (3) is a heat exchanger.

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