A self-ignition flue gas purification system and method

Abstract

The present invention discloses a self-ignition flue gas purification system and method. The disclosed self-ignition flue gas purification system includes a dust removal device, a denitrification device and an exhaust pipe which are sequentially connected through a flue gas pipeline, and also includes a self-ignition device connected to the exhaust pipe through the flue gas pipeline; the self-ignition device is used to burn CO in the flue gas to be treated, so that the flue gas to be treated spontaneously ignites to remove pollutants in the flue gas to be treated. In this way, CO in the flue gas to be treated can be fully utilized as fuel to make the flue gas to be treated spontaneously ignite, and the addition of external fuel can be eliminated, which can greatly reduce the energy consumption of flue gas purification. In the process of flue gas spontaneous combustion, carbon monoxide, VOCs and dioxins can be converted into non-pollutants such as carbon dioxide or water, and pollutants in the flue gas to be treated can be removed, and pollutants can be avoided or reduced from entering the absorption slurry such as desulfurization, thereby eliminating the need for subsequent treatment of the absorption slurry.

Description

Technical Field

[0001] The invention relates to a flue gas purification technology, and in particular to a self-ignition type flue gas purification system and a self-ignition type flue gas purification method. Background Art

[0002] The flue gas emitted by combustion furnaces (sintering furnaces, shaft furnaces, rotary kilns and blast furnaces) includes dust, NO X 、SOx、CO(6-100kmg / NM 3 )、VOCs(1000mg / NM 3 ), dioxins and other harmful pollutants. In order to reduce harmful pollutants in flue gas, it is usually necessary to purify the flue gas.

[0003] The flue gas purification process generally includes dust removal, desulfurization, denitrification, and then emptying, so that nitrate and sulfur can be removed before emptying to achieve flue gas purification. Among them, volatile organic compounds (VOCs) and dioxins often enter the absorption slurry during the desulfurization and denitrification process and become components of the absorption slurry. In the process of filtering the absorption slurry, harmful substances formed by VOCs and dioxins will remain in the filter cake, which will make the filter cake difficult to handle and become an important obstacle to the use of the filter cake. In the prior art, either the absorption slurry is specially treated or the filter cake is specially treated, and these treatments lead to complex processes and increased costs.

[0004] In addition, according to the existing flue gas treatment process, after dust removal, the flue gas temperature is relatively low, which is not conducive to denitrification treatment. It is necessary to set up special heating or temperature-increasing means to increase the flue gas temperature entering the denitrification device, resulting in higher energy consumption for flue gas treatment.

[0005] How to further improve the flue gas purification effect, reduce the adverse effects of harmful pollutants, reduce the cost of flue gas purification treatment, and reduce the energy consumption of flue gas purification are technical problems that technical personnel in this field need to solve. Summary of the invention

[0006] The purpose of the present invention is to provide a self-ignition flue gas purification system, which can use the combustible components in the flue gas to be treated as an energy source to achieve spontaneous combustion of the flue gas, remove pollutants in the flue gas, and reduce the energy consumption of flue gas purification.

[0007] At the same time, correspondingly, the present invention also provides a self-ignition flue gas purification method, through which the same effect can be achieved.

[0008] The self-ignition flue gas purification system provided by the present invention includes a dust removal device, a denitrification device and an exhaust pipe which are sequentially connected through a flue gas pipeline, and also includes a self-ignition device connected to the exhaust pipe through a flue gas pipeline; the self-ignition device is used to burn CO in the flue gas to be treated, so that the flue gas to be treated spontaneously ignites to remove pollutants in the flue gas to be treated. In this way, the CO in the flue gas to be treated can be fully utilized as fuel to make the flue gas to be treated spontaneously ignite, and the addition of external fuel can be unnecessary, or the addition of external fuel can be greatly reduced, thereby greatly reducing the energy consumption of flue gas purification. During the flue gas spontaneous combustion process, pollutants in the flue gas to be treated can be removed, and VOCs and dioxins can be avoided or reduced from entering the absorption slurry such as desulfurization, thereby eliminating the subsequent treatment process of the absorption slurry. The self-ignition flue gas purification system reduces the cost of flue gas de-VOCs, de-dioxins, denitrification, and desulfurization.

[0009] In the preferred technical solution, the self-ignition device is connected between the dust removal device and the denitrification device through the flue gas duct. Since the flue gas to be treated needs to be heated to a certain temperature when the denitrification device performs denitrification treatment, and the temperature of the flue gas discharged from the combustion furnace and after the dust removal treatment is lower than the temperature required for denitrification. After the flue gas to be treated is self-ignited through the self-ignition device, after the pollutants such as VOCs and dioxins are removed, the temperature of the flue gas to be treated can be increased, which can provide good conditions for the denitrification treatment, and can reduce the energy consumption of heating the flue gas before denitrification, thereby reducing costs, that is, the self-ignition treatment can achieve the function and effect of preheating the denitrification flue gas.

[0010] A further preferred technical solution also includes a preheating heat exchanger; the preheating heat exchanger includes a first passage and a second passage for heat exchange; the smoke inlet of the first passage is connected to the smoke outlet of the dust removal device through a smoke pipe, and the smoke outlet is connected to the smoke inlet of the spontaneous combustion device through a smoke pipe; the smoke inlet of the second passage is connected to the smoke outlet of the denitrification device through a smoke pipe, and the smoke outlet is connected to the exhaust pipe through a smoke pipe. Through the preheating heat exchanger, the heat in the smoke after the denitrification treatment can be used to preheat the smoke entering the spontaneous combustion device, so as to make full use of the system heat, reduce or lower the consumption of the spontaneous combustion device, and improve the overall efficiency of the system.

[0011] In a further technical solution, the self-ignition flue gas purification system further comprises a desulfurization device, which is connected between the exhaust port of the denitrification device and the exhaust pipe through a flue gas pipeline;

[0012] It also includes a whitening heat exchanger: the whitening heat exchanger includes a whitening flue gas channel and a whitening gas channel for heat exchange; the smoke inlet of the whitening flue gas channel is connected to the smoke outlet of the dust removal device through a flue gas pipeline, and the outlet is connected to the smoke inlet of the desulfurization device through a flue gas pipeline; the inlet of the whitening gas channel is connected to the outlet of the whitening fan through a flue gas pipeline to introduce whitening gas, and the outlet is connected to the exhaust pipe through a flue gas pipeline. The whitening heat exchanger can use the heat in the flue gas after denitrification to preheat the whitening gas. The preheated whitening gas is mixed with the gas to be exhausted, which can increase the exhaust flue gas temperature, reduce the flue gas humidity, reduce or eliminate the white smoke phenomenon of the exhaust flue gas, and reduce the corrosion of the exhaust pipe by the exhaust flue gas.

[0013] In the preferred technical solution, the self-ignition device includes an ignition device to burn the CO in the flue gas to be treated. Unlike the incineration device, the ignition device in the self-ignition device only ignites the treated flue gas at the initial stage with a lower temperature or under specific working conditions.

[0014] In the preferred technical solution, the spontaneous combustion device includes a spontaneous combustion controller, a spontaneous combustion furnace, and multiple energy storage oxidation furnaces connected to the spontaneous combustion furnace; each energy storage oxidation furnace includes an oxidation chamber, a smoke inlet branch pipe and a smoke outlet branch pipe connected to the oxidation chamber; the smoke inlet branches of multiple energy storage oxidation furnaces are connected to the smoke inlet of the spontaneous combustion device; the smoke outlet branches of multiple energy storage oxidation furnaces are connected to the smoke outlet of the spontaneous combustion device; the smoke inlet branch pipe and the smoke outlet branch pipe are provided with an electrically controlled switch valve; the control end of the spontaneous combustion controller is respectively connected to the signal input end of the electrically controlled switch valve to control the oxidation of the energy storage oxidation furnace. In this way, each energy storage oxidation furnace can work intermittently, keep the temperature of each energy storage oxidation furnace within a suitable range, avoid overheating of the energy storage oxidation furnace, and improve the reliability and service life of the spontaneous combustion device.

[0015] In a further optional technical solution, a heat insulation structure is provided between the plurality of oxidation chambers.

[0016] In an optional technical solution, an exhaust dust collector is provided in the exhaust pipe, and the exhaust dust collector is located between the outlet of the white elimination gas channel and the connecting position of the exhaust pipe.

[0017] In an optional technical solution, a demister is further provided in the exhaust pipe, and the demister is located before the exhaust dust collector.

[0018] The self-ignition flue gas purification method provided by the present invention includes treating the flue gas to be treated through a dust removal step and a denitration step and then emptying it. The flue gas to be treated has an appropriate content of CO, and before emptying it, it also includes a self-ignition step; the self-ignition step includes: burning CO in the flue gas to be treated, and then causing the flue gas to be treated to self-ignite, and removing pollutants such as carbon monoxide, VOCs and dioxins in the flue gas. Corresponding to the above-mentioned self-ignition flue gas purification system, the self-ignition flue gas purification method can make full use of the CO in the flue gas to be treated as fuel, causing the flue gas to be treated to self-ignite, and removing pollutants in the flue gas to be treated during the self-ignition process. It does not require the addition of external fuel or can greatly reduce the addition of external fuel, thereby greatly reducing the energy consumption of flue gas purification. During the self-ignition process, VOCs and dioxins can be converted into carbon dioxide or water at the same time, avoiding or reducing the entry of VOCs and dioxins into the desulfurization absorption slurry or other slurries, eliminating the subsequent treatment process of the slurry, and reducing the cost of self-ignition flue gas purification.

[0019] In the preferred technical solution, the self-ignition step is before the denitration step; after the temperature of the flue gas to be purified is raised to the denitration temperature through the self-ignition step, the denitration preparation temperature is between 250 degrees and 450 degrees. While removing VOCs and dioxins through the self-ignition device, the temperature of the flue gas to be treated can be raised to between 250 degrees and 450 degrees, providing suitable temperature conditions for denitration treatment, and eliminating the process and steps of heating the flue gas before denitration, thereby reducing energy consumption, simplifying the treatment process, and reducing the cost of flue gas purification.

[0020] In the preferred technical solution, the flue gas treated in the denitration step is used to heat the flue gas to be treated in the spontaneous combustion step. The heat in the flue gas treated with denitration can be used to preheat the flue gas entering the spontaneous combustion step, making full use of the system heat, facilitating the spontaneous combustion step, reducing dependence on ignition, and improving the overall efficiency of the system.

[0021] In the preferred technical solution, after the denitration step and before the exhaust, a desulfurization step is also included; the flue gas after the denitration treatment is desulfurized by the desulfurization step; and the step of heating the predetermined whitening gas by using the flue gas after the denitration step and between the desulfurization steps, and mixing the heated whitening gas with the flue gas in the desulfurization step is also included. In this way, the heat in the flue gas after the denitration treatment can be used to preheat the whitening gas, and the preheated whitening gas is mixed with the gas to be exhausted, which can increase the exhaust gas temperature, reduce or eliminate the white smoke phenomenon of the exhaust flue gas, and reduce the corrosion of the exhaust pipe by the exhaust flue gas. BRIEF DESCRIPTION OF THE DRAWINGS

[0022] Figure 1 It is a structural schematic diagram of an embodiment of the self-ignition flue gas purification system of the present invention.

[0023] Figure 2 The figure is a flow chart of an embodiment of the self-ignition flue gas purification method of the present invention. DETAILED DESCRIPTION

[0024] The following describes the embodiments of the self-ignition flue gas purification system and the self-ignition flue gas purification method provided by the present invention in conjunction with the accompanying drawings. In this document, the meanings of the directional words such as "front" and "back" are determined by considering the implementation status and process sequence of the self-ignition flue gas purification system and the self-ignition flue gas purification method, and should not be understood as any limitation on this patent. In addition, in this document, "spontaneous combustion" refers to the combustion without adding external fuel by utilizing the characteristics of the components in the flue gas to be treated. "Spontaneous combustion" can be carried out by ignition of an external fuel or device, or by adding air or oxygen to allow CO to burn.

[0025] Please refer to Figure 1 , which is a schematic structural diagram of an embodiment of a self-ignition type flue gas purification system of the present invention. The self-ignition type flue gas purification system comprises a dust removal device 100, a denitrification device 200, an exhaust pipe 300 and a self-ignition device 400 which are sequentially connected through a flue gas pipeline.

[0026] The dust removal device 100 can select existing dust removal equipment or utilize existing dust removal methods to remove dust from the flue gas to be treated. In one embodiment, the dust removal device 100 can include a cyclone dust collector and a pulse bag dust collector. Of course, according to actual needs, multiple dust collectors can be selected for combined use.

[0027] The denitration device 200 can utilize existing denitration equipment or denitration methods to eliminate or reduce NOx in the flue gas, such as oxidation method or reduction method. In this embodiment, the selective catalytic reduction (SCR) method is used for denitration, that is, hot ammonia is added, and the catalyst in the reactor is used to convert NOx into nitrogen to achieve the purpose of flue gas denitration.

[0028] After the flue gas reaches the emission standard through purification, it can be discharged into the air through the exhaust pipe 300. The exhaust pipe 300 can be selected to have a suitable height, and a chimney can be formed to discharge the gas that reaches the emission standard into the atmosphere at a suitable height.

[0029] The spontaneous combustion device 400 may include a spontaneous combustion furnace, which may be a direct-fired combustion furnace or a regenerative thermal oxidizer (RTO). In one embodiment, a regenerative thermal oxidizer may be selected to reduce energy consumption and ensure safety. It is understood that the spontaneous combustion device 400 may include an ignition device to ignite CO in the flue gas to be treated to achieve spontaneous combustion of the flue gas to be treated. During the spontaneous combustion process of the flue gas to be treated, carbon monoxide, VOCs and dioxins may be heated and converted into harmless components such as carbon dioxide or water to achieve the effect of flue gas purification.

[0030] In one embodiment, a self-ignition device 400 is provided between the dust removal device 100 and the denitrification device 200 through an appropriate flue gas duct. The CO content in the flue gas to be treated is 7000-18000 mg / Nm 3 , VOCs content is 300-500 mg / Nm 3 , CO2 content is 12.0% (Vol), water content is 13.0% (Vol), dioxin content is 6-9ng TEQ / Nm 3 . Using the regenerative self-ignition furnace, the CO in the flue gas to be treated is burned while maintaining a temperature of 820-1100°C, causing the flue gas to spontaneously combust. According to the test, the CO content in the flue gas after spontaneous combustion treatment is about 100-800mg / Nm 3 , VOCs content is 5-8mg / Nm 3 , CO2 content is 12.4% (Vol), water content is 13.2% (Vol), dioxin content is <0.1ng TEQ / Nm 3 That is, after the spontaneous combustion process, CO is converted into CO2, and VOCs and dioxins are converted into carbon dioxide or water.

[0031] In another embodiment, a self-ignition device 400 is provided between the dust removal device 100 and the denitration device 200 through an appropriate flue gas duct. The CO content in the flue gas to be treated is 1200-2500 mg / Nm 3 , VOCs content is 1000-1500 mg / Nm 3 , CO2 content is 8.5% (Vol), water content is 12% (Vol), SO2 content is 500-600mg / Nm 3 , organic sulfur 300-500mg / Nm 3 , dioxin content is 1-5ng TEQ / Nm 3 Under the condition of maintaining the temperature of 800-1100℃, the CO and VOCs in the flue gas to be treated are burned, and the flue gas to be treated is spontaneously combusted. According to the test, the CO content in the flue gas after spontaneous combustion treatment is 200-600mg / Nm3 , VOCs content is 10-15mg / Nm 3 , CO2 content is 8.8% (Vol), water content is 12.3% (Vol), dioxin content is <0.1ngTEQ / Nm 3 , SO2 content is 900-1200mg / Nm 3 That is, after the spontaneous combustion treatment, CO is converted into CO2, VOCs and dioxins are converted into carbon dioxide or water, and organic sulfur is converted into SO2.

[0032] In this way, CO in the flue gas to be treated can be fully utilized as fuel to make the flue gas to be treated self-ignite, and the addition of external fuel can be unnecessary, or the addition of external fuel can be greatly reduced, thereby greatly reducing the energy consumption of flue gas purification. In the process of flue gas self-ignition, VOCs, dioxins and / or organic sulfur can be converted into carbon dioxide, water and sulfur dioxide, and sulfur dioxide can be easily removed in the subsequent desulfurization treatment process, thereby achieving the removal of pollutants such as VOCs, dioxins and organic sulfur, avoiding or reducing the entry of VOCs, dioxins and organic sulfur into the desulfurization absorption slurry, and eliminating the subsequent treatment process of the desulfurization absorption slurry.

[0033] It is understood that the CO content of the flue gas to be treated can be kept within an appropriate range, and the flue gas to be treated can be spontaneously combusted by existing ignition methods, or by maintaining an appropriate temperature to keep the flue gas to be treated spontaneously combusted. In a preferred embodiment, the CO content of the flue gas to be treated is greater than 6000 mg / Nm 3 When the smoke to be treated is burned, the self-ignition of the smoke to be treated can be achieved; of course, those skilled in the art can make the smoke to be treated burn by igniting the smoke at the beginning and then keep it burning according to the self-ignition environment, the components in the smoke to be treated and the ratio between the components. According to the above description, it can also be determined that the higher the combustible components in the smoke to be treated, the better the self-ignition performance; according to the different self-ignition performance of the smoke to be treated, the temperature in the combustion furnace can be controlled to balance the heat resistance of the self-ignition device 400 and the smoke purification efficiency.

[0034] In addition, it is particularly important that, when the denitrification device 200 performs denitrification treatment, the flue gas to be treated needs to be heated to a certain temperature, and the temperature of the flue gas discharged from the combustion furnace after dust removal treatment is lower than the temperature required for denitrification. By using the embodiment of the present invention, after the pollutants such as VOCs and dioxins are removed by the self-ignition device 400, the temperature of the flue gas to be treated can be increased to 250 to 450 degrees, which can provide good conditions for denitrification treatment, and can save the process and steps of heating the flue gas before denitrification, that is, the self-ignition treatment can achieve the function and effect of denitrification preheating, and reduce the cost of flue gas purification treatment. Generally speaking, for a project with a flue gas volume of 100,000 Nm3 / h, using the existing technology, the annual fuel cost is about 8 million yuan when the flue gas to be treated is increased by adding fuel; using the technology provided by this patent, the annual fuel cost (only for igniting the flue gas to be treated) is only 1 million yuan, which greatly reduces the cost of flue gas purification.

[0035] Of course, the main purpose of the present invention is to make full use of CO in the flue gas to be treated, burn CO, burn the flue gas to be treated, remove pollutants in the flue gas to be treated during the combustion process, and do not need or greatly reduce the addition of external fuel, thereby greatly reducing the energy consumption of flue gas purification. At the same time, it can avoid or reduce the shortcomings of complex process and high treatment cost caused by the presence of VOCs and dioxins in the spontaneous combustion flue gas purification process. Therefore, the setting position of the spontaneous combustion device 400 can be determined according to actual needs, as long as it is connected to the exhaust pipe 300 through the flue gas pipeline, and it does not have to be set between the dust removal device 100 and the denitrification device 200.

[0036] It is understood that in order to ensure the self-ignition effect, the self-ignition device 400 may include an ignition device to burn the CO in the flue gas to be treated. This can ensure the reliability of CO combustion, the combustion effect, and the flue gas purification effect.

[0037] As shown in the figure, the self-ignition flue gas purification system provided in this embodiment may also include a preheating heat exchanger 500; the preheating heat exchanger 500 is arranged between the dust collector device 100 and the self-ignition device 400. The preheating heat exchanger 500 includes a first passage and a second passage for heat exchange. The first passage provides a flue gas channel, including a smoke inlet 511 and a smoke outlet 512. The smoke inlet 511 is communicated with the smoke outlet 102 of the dust collector 100 through a smoke pipe, and the smoke outlet 512 is communicated with the smoke inlet 401 of the self-ignition device 400 through a smoke pipe. The second passage provides a channel for the flue gas discharged from the denitrification device 200, and its smoke inlet 521 is communicated with the smoke outlet 202 of the denitrification device 200 through a smoke pipe, and the smoke outlet 522 is directly or indirectly communicated with the exhaust pipe 300 through a smoke pipe. The temperature of the flue gas discharged from the denitrification device 200 is relatively high, while the temperature of the flue gas discharged from the dust removal device 100 is relatively low; the two can exchange heat through the preheating heat exchanger 500, thereby increasing the temperature of the flue gas entering the self-ignition device 400 and reducing the temperature of the flue gas discharged from the denitrification device 200. Through the preheating heat exchanger 500, the heat in the flue gas after denitrification treatment can be used to preheat the flue gas entering the self-ignition device 400, making full use of the system heat, reducing or lowering the consumption of the self-ignition device 400, and improving the overall efficiency of the system. Any equipment with flue gas heat exchange function can be used as the preheating heat exchanger 500 in the present invention, and the present invention has no special restrictions on this.

[0038] In order to promote the smooth flow of smoke, a corresponding induced draft fan may be provided in the smoke passage in front of the first passage of the preheating heat exchanger 500 to promote the flow of smoke.

[0039] like Figure 1 As shown, the self-ignition flue gas purification system provided in this embodiment also includes a desulfurization device 600 and a whitening heat exchanger 700.

[0040] The desulfurization device 600 is connected between the exhaust port 202 of the denitrification device 200 and the exhaust pipe 300 through a flue gas pipeline. In this way, the flue gas after denitrification can enter the desulfurization device 600 for desulfurization. The desulfurization device 600 can use existing desulfurization equipment, such as a multiphase reactor or a spray tower; wet desulfurization can be selected, or dry desulfurization can be selected. In order to control the flue gas entering the desulfurization device 600 and ensure smooth flow of the flue gas, an appropriate induced draft fan can be set in the flue gas introduction pipeline of the desulfurization device 600.

[0041] The desulphurization heat exchanger 700 can be connected after the denitrification device 200. In this embodiment, the desulphurization heat exchanger 700 is arranged after the preheating heat exchanger 500. The desulphurization heat exchanger 700 includes a desulphurization flue gas channel and a desulphurization gas channel for heat exchange. The smoke inlet 711 of the desulphurization flue gas channel is communicated with the smoke outlet 202 of the denitrification device 200 through an appropriate smoke pipe, and the smoke outlet 712 is communicated with the smoke inlet of the desulfurization device 600 through a smoke pipe. The desulphurization gas is introduced into the inlet 721 of the desulphurization gas channel, and the outlet 722 is communicated with the exhaust pipe 300 through a smoke pipe. The desulphurization gas can be air, and of course it can also be other gases. In order to control the introduction of the desulphurization gas, an appropriate induced draft fan can be provided at the inlet 721 of the desulphurization gas channel to control the introduction of the desulphurization gas (air).

[0042] In this embodiment, the working principle of the de-whitening heat exchanger 700 is: use the heat in the flue gas after denitrification treatment to preheat the air, and mix the preheated air with the purified gas to be exhausted, which can increase the temperature of the exhaust gas, reduce the white smoke phenomenon of the exhaust gas, and reduce the corrosion of the exhaust pipe 300 by the exhaust body.

[0043] In order to avoid overheating of the self-ignition device 400 and affect the reliability and service life of the self-ignition device 400, the self-ignition device 400 in the self-ignition flue gas purification system includes a self-ignition controller (not shown in the figure), a self-ignition furnace 420 and a plurality of energy storage oxidation furnaces 410 connected to the self-ignition furnace 420. The self-ignition furnace 420 provides space for the self-ignition of the treated flue gas. In this embodiment, a plurality of energy storage oxidation furnaces 410 are located above the self-ignition furnace 420. Each energy storage oxidation furnace 410 also includes an oxidation chamber 411, a smoke inlet branch pipe 412 and a smoke outlet branch pipe 413 connected to the oxidation chamber 411; the smoke inlet branch pipes 412 of the plurality of energy storage oxidation furnaces 410 are connected to the smoke inlet port 401 of the self-ignition device 400; the smoke outlet branch pipes 413 of the plurality of energy storage oxidation furnaces 410 are connected to the smoke outlet 402 of the self-ignition device 400. The oxidation chamber 411 provides combustion or combustion preparation for the flue gas or combustible components.

[0044] In this embodiment, the smoke inlet branch pipe 412 and the smoke outlet branch pipe 413 are provided with electrically controlled switch valves to control the on-off of the pipelines, realize the entry and discharge of smoke, and further control the smoke entry, smoke cleaning and discharge process of each energy storage oxidation furnace 410, thereby controlling the working cycle of each energy storage oxidation furnace 410.

[0045] The control end of the self-ignition controller is respectively connected to the signal input end of the electric control switch valve. In this way, each self-ignition furnace can work intermittently, and the temperature of each energy storage oxidation furnace 410 and oxidation chamber 411 is kept within a suitable range, so as to avoid overheating of the energy storage oxidation furnace 410 and oxidation chamber 411, and improve the reliability and service life of the self-ignition device 400.

[0046] The self-ignition furnace 420 may be provided with an ignition device to ignite the flue gas at the beginning or when the temperature is low, and provide a prerequisite for the flue gas to self-ignite. A heat insulation structure is provided between the oxidation chambers 411 of the multiple energy storage oxidation furnaces 410, such as filling with heat insulation materials, etc., so as to prevent the oxidation chambers 411 from affecting each other, and further improve the reliability and service life of the self-ignition device 400.

[0047] It is understandable that the self-ignition device 400 may include only one energy storage oxidation furnace 410 or multiple energy storage oxidation furnaces 410 .

[0048] In order to further purify the flue gas and ensure that the exhaust gas meets the standard, in this embodiment, an exhaust dust collector 310 and a demister 320 are also provided in the exhaust pipe 300. The exhaust dust collector 310 is located between the outlet 722 of the white gas elimination channel and the connection position of the exhaust pipe 300. The demister 320 can be located before the exhaust dust collector 310 to reduce the water content in the gas and reduce the corrosive effect on the dust collector 310. Of course, an online monitoring device can also be provided in the exhaust pipe 300 to monitor the pollutant content of the exhaust gas in real time.

[0049] Based on the above self-ignition flue gas purification system, the present invention also provides a self-ignition flue gas purification method. Of course, the self-ignition flue gas purification method provided by the present invention can be implemented in the above self-ignition flue gas purification system, but is not limited to the above self-ignition flue gas purification system.

[0050] Please refer to Figure 2 , which is a schematic diagram of the principle of an embodiment of the spontaneous combustion type flue gas purification method of the present invention. In this embodiment, the spontaneous combustion type flue gas purification method comprises the following steps for treating the flue gas to be treated:

[0051] S100, dust removal step, that is, dust removal treatment of the flue gas discharged from the combustion furnace to avoid blockage of the subsequent spontaneous combustion flue gas preheating and denitrification process equipment. After dust removal treatment, the flue gas to be treated has a predetermined content of CO, such as greater than 6000mg / NM 3 , to facilitate the ignition of CO, and then promote the spontaneous combustion of the flue gas to be treated.

[0052] S200, a spontaneous combustion flue gas preheating step, i.e. using the flue gas treated in the denitrification step to preheat the flue gas to be treated in the spontaneous combustion step, and transferring the heat of the flue gas treated in the denitrification step to the flue gas to be treated in the spontaneous combustion step, so as to facilitate spontaneous combustion in the flue gas to be treated.

[0053] S300, the spontaneous combustion step, that is, the CO in the flue gas to be treated is burned, so that the flue gas to be treated is spontaneously combusted, and pollutants in the flue gas are removed. Corresponding to the above-mentioned spontaneous combustion flue gas purification system, a predetermined temperature can be maintained in the spontaneous combustion device to keep the flue gas to be treated spontaneously combusted; or the flue gas to be treated can be ignited by the ignition device to make the flue gas to be treated spontaneously combusted.

[0054] S400, a denitration step, removes NOx from the flue gas to be treated.

[0055] S500, the step of heating the white gas, i.e., using the flue gas to be treated after the denitration step to perform heat exchange with the air (white gas). Through this step, the temperature of the flue gas to be treated entering the desulfurization step can be reduced, and the temperature of the white gas can be increased. The reduction of the flue gas to be treated can reduce the evaporation amount in the desulfurization step; the increase of the white gas temperature can reduce the condensed water vapor during the flue gas discharge and reduce the white smoke phenomenon of the flue gas after exhaust.

[0056] S600, a desulfurization step, removes sulfur dioxide from the flue gas to be treated.

[0057] After being purified and meeting the exhaust conditions, it is discharged into the atmosphere through the exhaust pipe.

[0058] Corresponding to the above-mentioned self-ignition flue gas purification system, on the one hand, pollutants such as VOCs and dioxins can be converted into carbon dioxide or water or easily treatable parts, avoiding or reducing the entry of VOCs and dioxins into the desulfurization absorption slurry, eliminating the need for subsequent treatment processes, and reducing the cost of flue gas purification treatment; on the other hand, since the self-ignition step is arranged before the denitrification step, after the carbon monoxide, VOCs and dioxins are removed by the self-ignition device, the temperature of the flue gas to be treated is increased to between 250 and 450 degrees, which can eliminate the process and steps of heating the flue gas before denitrification, thereby reducing costs and reducing the energy consumption of flue gas purification.

[0059] It is understandable that the self-ignition step only needs to be before the emptying, and does not have to be set before the denitrification step. The specific steps can be arranged and set accordingly according to the type and composition of the flue gas to be treated and the requirements of the application environment.

[0060] In order to utilize the heat in the flue gas after denitration to preheat the flue gas entering the spontaneous combustion step, fully utilize the system heat, reduce or lower the consumption of the spontaneous combustion step, and improve the overall efficiency of the system, the flue gas treated in the denitration step is used to preheat the flue gas to be treated in the spontaneous combustion step. This can be achieved by the preheating heat exchanger 500.

[0061] Of course, in the case where the flue gas to be treated needs to be desulfurized, a desulfurization step can be included after the denitration step and before the exhaust. The desulfurization step is used to desulfurize the flue gas after the denitration treatment. In order to eliminate white smoke during the exhaust, the flue gas after the denitration step and between the desulfurization steps can be used to heat the air (white smoke elimination gas), and the heated air is introduced into the exhaust pipe 300 to increase the exhaust gas temperature, eliminate or reduce the white smoke phenomenon of the exhaust gas, and reduce the corrosion of the exhaust gas to the exhaust pipe.

[0062] The above is a detailed introduction to the specific implementation of the present invention. Specific examples are used in this article to illustrate the principles and implementation methods of the present invention. The description of the above embodiments is only used to help understand the core idea of ​​the present invention. It should be pointed out that for ordinary technicians in this technical field, without departing from the principle of the present invention, the present invention can also be improved and modified, and these improvements and modifications also fall within the scope of protection of the claims of the present invention.

Claims

1. A self-ignition flue gas purification system, comprising a dust removal device (100), a denitrification device (200) and an exhaust pipe (300) which are sequentially connected through a flue gas pipeline, characterized in that: It also includes a self-ignition device (400) connected to the exhaust pipe (300) through a smoke duct; The self-ignition device (400) is used to make the flue gas to be treated self-ignite by burning CO in the flue gas to be treated, so as to remove pollutants in the flue gas to be treated; The self-ignition device (400) is connected between the dust removal device (100) and the denitration device (200) via the flue gas duct; The spontaneous combustion device (400) comprises a spontaneous combustion controller, a spontaneous combustion furnace (420), and a plurality of energy storage oxidation furnaces (410) connected to the spontaneous combustion furnace (420); each energy storage oxidation furnace (410) comprises an oxidation chamber (411), a smoke inlet branch pipe (412) and a smoke outlet branch pipe (413) connected to the oxidation chamber (411); the smoke inlet branch pipes (412) of the plurality of energy storage oxidation furnaces (410) are connected to the smoke inlet (401) of the spontaneous combustion device (400); the smoke outlet branch pipes (413) of the plurality of energy storage oxidation furnaces (410) are connected to the smoke outlet (402) of the spontaneous combustion device (400); The smoke inlet branch pipe (412) and the smoke outlet branch pipe (413) are provided with electrically controlled switch valves; the control end of the spontaneous combustion controller is respectively connected to the signal input end of the electrically controlled switch valve; A heat insulation structure is arranged between the plurality of oxidation chambers.

2. The self-ignition flue gas purification system according to claim 1, characterized in that: It also includes a preheating heat exchanger (500); the preheating heat exchanger (500) includes a first passage and a second passage for heat exchange; the smoke inlet (511) of the first passage is communicated with the smoke exhaust port (102) of the dust removal device (100) through a smoke duct, and the smoke outlet (512) is communicated with the smoke inlet (401) of the self-ignition device (400) through a smoke duct; the smoke inlet (521) of the second passage is communicated with the smoke exhaust port (202) of the denitration device (200) through a smoke duct, and the smoke outlet (522) is communicated with the exhaust pipe (300) through a smoke duct.

3. The self-ignition flue gas purification system according to claim 1 or 2, characterized in that: It also includes a desulfurization device (600), wherein the desulfurization device (600) is connected between the smoke exhaust port (202) of the denitrification device (200) and the exhaust pipe (300) through a smoke duct; Also includes descaling heat exchanger (700): The desulfurization heat exchanger (700) comprises a desulfurization flue gas channel and a desulfurization gas channel for heat exchange; the smoke inlet (711) of the desulfurization flue gas channel is communicated with the smoke outlet (102) of the dust removal device (100) through a smoke duct, and the smoke outlet (712) is communicated with the smoke inlet of the desulfurization device (600) through a smoke duct; the desulfurization gas is introduced into the inlet (721) of the desulfurization gas channel, and the outlet (722) is communicated with the exhaust pipe (300) through a smoke duct.

4. The self-ignition flue gas purification system according to claim 1 or 2, characterized in that: The self-ignition device (400) comprises an ignition device to burn CO in the flue gas to be treated.

5. A self-ignition flue gas purification method using the self-ignition flue gas purification system according to any one of claims 1 to 4, comprising treating the flue gas to be treated through a dust removal step and a denitration step and then emptying the flue gas, characterized in that: The CO contained in the flue gas to be treated also includes a spontaneous combustion step before being discharged; The spontaneous combustion step includes: burning CO in the flue gas to be treated, causing the flue gas to be treated to spontaneously combust, so as to remove pollutants in the flue gas; The auto-ignition step is before the denitration step; Through the self-ignition step, after the temperature of the flue gas to be purified is raised to the denitration temperature, the denitration preparation temperature is between 250 degrees and 450 degrees.

6. The self-ignition flue gas purification method according to claim 5, characterized in that: The flue gas treated in the denitration step is used to heat the flue gas to be treated in the spontaneous combustion step.

7. The self-ignition flue gas purification method according to claim 5 or 6, characterized in that: After the denitrification step and before emptying, a desulfurization step is also included; Desulfurization is performed on the flue gas after denitration through the desulfurization step; The method further comprises the steps of heating a predetermined denitrification gas by using the flue gas after being processed in the denitrification step and before being processed in the desulfurization step, and mixing the heated denitrification gas with the flue gas processed in the desulfurization step.

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