Hazardous waste flue gas treatment system

Abstract

The utility model discloses a hazardous waste flue gas treatment system which sequentially comprises a waste heat boiler, a quench tower, a cloth bag dust collector, heat storage type combustion equipment and desulfurization and denitrification equipment in the flue gas emission direction, and a flue gas inlet of the waste heat boiler is connected with a flue gas outlet of a smelting furnace flue. The waste heat boiler, the quench tower, the bag collector, the heat accumulating type combustion equipment and the desulfurization and denitrification equipment are connected through pipelines respectively. Under the condition that technological processes and equipment are not increased, by optimizing production equipment and the technological processes, multi-stage elimination of harmful components in the hazardous waste flue gas can be achieved so that the flue gas can be discharged in a standard reaching mode, meanwhile, use of production materials in the flue gas purification treatment process can be reduced, and economic benefits can be improved.

Description

Technical Field

[0001] The utility model relates to the technical field of flue gas treatment, in particular to a hazardous waste flue gas treatment system. Background Art

[0002] Hazardous wastes are diverse and complex in composition, often containing large amounts of organic matter, nitrogen, sulfur, phosphorus, and halogen elements. Whether incinerated or treated through oxygen-enriched smelting, hazardous flue gas is inevitably generated. This flue gas typically contains one or more toxic gases, including VOCs, CO, H₂S, SO₂, HCl, NH₃, NOx, HF, and dioxins. To remove these toxic gases before discharge, flue gas purification is required to comply with the "Hazardous Waste Incineration Pollution Control Standard" (GB18484-2020).

[0003] At present, the traditional hazardous waste flue gas purification process in China is very mature, and the process equipment generally adopts a secondary combustion chamber + waste heat boiler + quenching tower + bag filter + desulfurization and denitrification equipment in this order. However, the existing hazardous waste flue gas purification process still has the following shortcomings:

[0004] 1. SCR denitrification is used to remove NOx from hazardous waste flue gas, which is a one-stage removal method with low denitrification efficiency;

[0005] 2. The removal of CO and VOC in hazardous waste flue gas adopts secondary combustion chamber combustion, which is a first-level removal. It is inevitable that unburned CO and VOC waste gas will remain. Even if oxygen-enriched smelting technology is used to treat hazardous waste, the CO concentration in the flue gas after secondary combustion is less than 5000 mg / m 3 above;

[0006] 3. Dioxin removal from hazardous waste flue gas uses secondary combustion chamber and activated carbon physical adsorption, which is a two-stage removal method. However, the dioxin removal process is always before the bag dust collector, which results in the presence of dioxin-generating catalysts in the flue gas. During the temperature reduction process, the catalyst will promote the re-synthesis of dioxins, resulting in poor removal effect. Summary of the Invention

[0007] Therefore, the purpose of the present invention is to provide a hazardous waste flue gas treatment system to at least solve one of the above technical problems.

[0008] The utility model provides a hazardous waste flue gas treatment system, which includes a waste heat boiler, a quenching tower, a bag dust collector, a thermal storage combustion device and a desulfurization and denitrification device in sequence along the flue gas emission direction. The flue gas inlet of the waste heat boiler is connected to the flue gas outlet of the smelting furnace flue, and the waste heat boiler, the quenching tower, the bag dust collector, the thermal storage combustion device and the desulfurization and denitrification equipment are respectively connected by pipelines.

[0009] By adopting the above technical solution, the utility model can achieve multi-stage elimination of harmful components in hazardous waste flue gas by optimizing production equipment and process flow without increasing process flow and equipment conditions, so that the flue gas can meet emission standards. At the same time, it can reduce the use of production materials in the flue gas purification process and improve economic benefits.

[0010] In some embodiments, the waste heat boiler is provided with at least a first flue, a second flue, and a third flue connected end to end and arranged in parallel, and the centerline direction of the first flue coincides with the vertical direction of the centerline of the flue gas outlet of the smelting furnace flue.

[0011] In some embodiments, the waste heat boiler is further provided with a fourth flue and a fifth flue arranged in parallel with the third flue, and the third flue, the fourth flue and the fifth flue are arranged end to end.

[0012] In some embodiments, the water-cooled wall of the first flue is provided with a combustion-preventing zone.

[0013] In some embodiments, the height of the first flue is not less than 10 m, and the residence time of the flue gas in the first flue is not less than 2 s.

[0014] In some embodiments, a plurality of first SNCR denitrification reserved holes are provided in an area of ​​the second flue where the flue gas temperature is 1000° C.±100° C.

[0015] In some embodiments, the flue gas inlet of the waste heat boiler and the flue gas outlet of the smelting furnace flue are connected via an expansion joint.

[0016] In some embodiments, a plurality of atomizing spray guns are provided on the upper portion of the quenching tower, and a plurality of activated carbon reserved holes are provided on the inner wall of the quenching tower.

[0017] In some embodiments, the regenerative combustion device includes a regenerative chamber and a combustion chamber, wherein the combustion chamber is provided with a natural gas burner and a temperature feedback device, and the temperature feedback device can be used to adjust the amount of natural gas of the natural gas burner according to the temperature of the combustion chamber.

[0018] In some embodiments, a plurality of second SNCR denitrification reserved holes are provided in the combustion chamber.

[0019] Compared with the prior art, the beneficial effects of the present invention are:

[0020] 1. By utilizing the temperature change of high-temperature flue gas, SNCR denitrification is added to the waste heat boiler and regenerative combustion equipment. This allows the NOx in hazardous waste flue gas to undergo two-stage SNCR denitrification and one-stage SCR denitrification, thereby improving the denitrification efficiency and reducing the use of catalysts in the SCR denitrification process;

[0021] 2. By rationally arranging the first flue in the waste heat boiler and forming a secondary combustion chamber with the middle and upper space of the smelting furnace, and adding a regenerative combustion device, CO and VOC waste gases in the hazardous waste flue gas can be removed in two stages and complete combustion can be ensured;

[0022] 3. By adding a regenerative combustion device after the bag filter, dioxins remaining in the hazardous waste flue gas can be removed through three stages: combustion in a secondary combustion chamber, physical adsorption on activated carbon, and re-combustion in the regenerative combustion device. Furthermore, even if the flue gas temperature subsequently decreases, the flue gas will be less likely to synthesize dioxins due to the lack of dioxin-forming catalysts (copper-containing substances) after passing through the waste heat boiler, quenching tower, and bag filter, thus ensuring complete dioxin removal.

[0023] 4. By directly connecting the waste heat boiler to the flue gas outlet of the smelting furnace, adding a regenerative combustion device between the bag dust collector and the desulfurization and denitrification equipment, and optimizing the waste heat boiler, quenching tower, and regenerative combustion equipment, the hazardous waste flue gas can eventually meet the "Hazardous Waste Incineration Pollution Control Standards". BRIEF DESCRIPTION OF THE DRAWINGS

[0024] The above and / or additional aspects and advantages of the present invention will become apparent and easily understood from the description of the embodiments in conjunction with the following drawings:

[0025] Figure 1 This is a schematic diagram of a hazardous waste flue gas treatment system of the present utility model;

[0026] In the figure: 10-smelting furnace flue, 20-waste heat boiler, 21-first flue, 22-second flue, 231-third flue, 232-fourth flue, 233-fifth flue, 24-fired belt, 25-first SNCR denitrification reserved hole, 26-high temperature resistant flexible three-dimensional non-metallic expansion joint, 27-flue gas outlet, 30-quenching tower, 31-atomizing spray gun, 32-activated carbon reserved hole, 40-bag dust collector, 50-regenerative combustion equipment, 51-regenerator, 52-combustion chamber, 53-second SNCR denitrification reserved hole, 60-desulfurization and denitrification equipment. DETAILED DESCRIPTION

[0027] To better understand the present invention, various aspects of the present invention will be described in more detail with reference to the accompanying drawings. It should be understood that these detailed descriptions are merely illustrations of embodiments of the present invention and are not intended to limit the scope of the present invention in any way. It should be noted that in this specification, terms such as first, second, and third are used solely to distinguish one feature from another and do not constitute any limitation on the features.

[0028] It should also be understood that the terms “comprises,” “including,” “having,” “includes,” and / or “comprising,” when used in this specification, indicate the presence of stated features, elements, and / or components, but do not preclude the presence or addition of one or more other features, elements, components, and / or combinations thereof.

[0029] Unless otherwise defined, all terms used herein (including technical and scientific terms) have the same meaning as commonly understood by those skilled in the art to which the present invention pertains. It should also be understood that terms (such as those defined in commonly used dictionaries) should be interpreted as having a meaning consistent with their meaning in the context of the relevant technology and will not be interpreted in an idealized or overly formal sense unless explicitly defined herein.

[0030] See also Figure 1 An embodiment of the present invention proposes a hazardous waste flue gas treatment system, which includes a waste heat boiler 20, a quenching tower 30, a bag dust collector 40, a thermal storage combustion device 50 and a desulfurization and denitrification device 60 in sequence along the flue gas emission direction. Among them, the flue gas inlet of the waste heat boiler 20 is directly connected to the flue gas outlet of the smelting furnace flue 10 through an expansion joint, the flue gas outlet of the waste heat boiler 20 is connected to the flue gas inlet of the quenching tower 30 through a pipe, the flue gas outlet of the quenching tower 30 is connected to the flue gas inlet of the bag dust collector 40 through a pipe, the flue gas outlet of the bag dust collector 40 is connected to the flue gas inlet of the thermal storage combustion equipment 50 through a pipe, the flue gas outlet of the thermal storage combustion equipment 50 is connected to the flue gas inlet of the desulfurization and denitrification equipment 60 through a pipe, and the flue gas outlet of the desulfurization and denitrification equipment 60 is the final discharge outlet of the hazardous waste flue gas, that is, the hazardous waste flue gas is purified in sequence by the waste heat boiler 20, the quenching tower 30, the bag dust collector 40, the thermal storage combustion equipment 50 and the desulfurization and denitrification equipment 60 and then discharged into the atmosphere.

[0031] The embodiment of the utility model directly connects the waste heat boiler to the flue gas outlet of the smelting furnace flue and adds a regenerative combustion device between the bag dust collector and the desulfurization and denitrification equipment, so that the CO and VOC waste gases in the hazardous waste flue gas can be removed in two stages to ensure complete combustion; at the same time, by optimizing the waste heat boiler, the quenching tower, and the regenerative combustion equipment, the hazardous waste flue gas can eventually meet the "Hazardous Waste Incineration Pollution Control Standards".

[0032] Specifically, at least three flues are provided in the waste heat boiler 20. In the embodiment of the present invention, five flues are provided in the waste heat boiler 20, namely, a first flue 21, a second flue 22, a third flue 231, a fourth flue 232, and a fifth flue 233 connected end to end. Among them, the centerline direction of the first flue 21 coincides with the vertical direction of the centerline of the flue gas outlet of the smelting furnace flue 10, and the flue gas inlet of the first flue 21 and the flue gas outlet of the smelting furnace flue 10 are connected by a high-temperature resistant flexible three-dimensional non-metallic expansion joint 26, so that a large amount of smoke can be settled in the first flue 21 and directly fall into the smelting pool, so as to reduce the transportation of return dust flue gas and the treatment of smoke dust in the flue gas; the second flue 22 is arranged parallel to the first flue 21 so that the smoke makes a 180° turn; the third flue 231, the fourth flue 232 and the fifth flue 233 are all arranged parallel to the second flue 22 so that the smoke makes two more 180° turns, so that larger particles in the smoke can settle at the bottom of the second flue 22, the third flue 231, the fourth flue 232 and the fifth flue 233 under the action of inertia, so as to further reduce the treatment of smoke dust in the flue gas.

[0033] As a further improvement to the present invention, a fire-prevention zone 24 is provided on the water-cooled wall of the first flue 21 to prevent the flue gas temperature from dropping too quickly and to ensure that the flue gas temperature at the top of the ascending channel of the first flue 21 is above 1100°C. More preferably, the height of the first flue 21 is set to 15m to 20m, so that the residence time or rise time of the flue gas in the first flue 21 is ≥ 2s. This allows the upper and middle spaces of the smelting furnace hearth and the first flue 21 to form a quasi-secondary combustion chamber, thereby purifying some toxic gases in the hazardous waste flue gas, particularly CO, VOC waste gases, and dioxins.

[0034] As a further improvement of the present invention, a plurality of first SNCR denitrification pre-holes 25 are provided on the left and right flues of the second flue 22 and in the region where the flue gas temperature is between 1050°C and 950°C. The first SNCR denitrification pre-holes 25 are arranged at intervals up and down and left and right. More preferably, at least 8 first SNCR denitrification pre-holes 25 are provided on the left and right flues of the second flue 22 and in the region where the flue gas temperature is between 1050°C and 950°C. The first SNCR denitrification pre-holes 25 can be precisely sprayed with an appropriate amount of SNCR denitrification reducing agent through a spray gun. At the same time, the SNCR denitrification reducing agent is made by quantitatively mixing a urea solution that is non-flammable and non-explosive, colorless, odorless, and non-corrosive with desalted water. In this way, NOx in hazardous waste flue gas can be preliminarily removed.

[0035] As a further improvement of the present invention, the flue gas outlet 27 of the waste heat boiler 20 is arranged at the top of the flue of the rising channel of the fifth flue 233, so that the flue gas temperature at the flue gas outlet 27 can be controlled to be maintained above 550°C.

[0036] Furthermore, the quenching tower 30 adopts a twin-tower structure, with multiple atomizing lances 31 disposed at the upper portion of the quenching tower 30, and multiple activated carbon pre-holes 32 provided on the inner wall of the quenching tower 30. In an embodiment of the present invention, the quenching tower 30 adopts a twin-tower structure, with at least 16 atomizing lances 31 evenly arranged on the same horizontal plane at the upper portion of the quenching tower 30. Atomized water can be sprayed through the nozzles of the atomizing lances 31, thereby increasing the residence time of the high-temperature flue gas in the quenching tower 30. Furthermore, the thorough mixing and evaporation of the water mist and the high-temperature flue gas can rapidly reduce the temperature of the flue gas entering the quenching tower 30 to approximately 200°C, thereby improving the rapid cooling effect. Multiple activated carbon pre-holes 32 are provided on the inner wall of the lower portion of the quenching tower 30, allowing the activated carbon to fully adsorb dioxins in the flue gas, further reducing the dioxins in the hazardous waste flue gas and improving the flue gas purification effect.

[0037] Furthermore, the bag filter 40 can be a conventional bag filter for collecting dust from the flue gas from the quench tower 30. The bag filter 40 body, which contacts the flue gas, is made of 304 stainless steel, and the filter bag in the bag filter 40 is made of polytetrafluoroethylene (PTFE) coated.

[0038] Furthermore, the above-mentioned regenerative combustion equipment 50 includes a regenerative chamber 51 and a combustion chamber 52. The regenerative combustion equipment 50 can adopt the method of natural gas regenerative combustion, so that the CO, VOC waste gas and dioxins in the flue gas are burned at high temperature in the combustion chamber 52 until the CO, VOC waste gas and dioxins are completely removed. At the same time, the heat storage body in the regenerative chamber 51 can be used to recover the waste heat of the flue gas in the combustion chamber 52, so as to reduce the natural gas usage of the regenerative combustion equipment 50 and preheat the outlet flue gas of the bag filter 40.

[0039] As a further improvement to the present invention, a natural gas burner and a temperature feedback device are provided in the combustion chamber 52. This temperature feedback device can be used to adjust the amount of natural gas supplied by the natural gas burner according to the temperature of the combustion chamber 52, thereby achieving stable control of the temperature of the entire regenerative combustion device 50 and maintaining the temperature of the combustion chamber 32 within 950°C ± 50°C (this temperature range is exactly the reaction temperature range for SNCR denitration). Simultaneously, multiple second SNCR denitration holes 53 are provided on the front, back, and top sides of the combustion chamber 32. In this embodiment of the present invention, 16 second SNCR denitration holes 53 are evenly arranged on the front, back, and top sides of the combustion chamber 32. These second SNCR denitration holes 53 can be precisely sprayed with an appropriate amount of SNCR denitration reducing agent using a spray gun to further remove NOx from the hazardous waste flue gas.

[0040] Furthermore, the above-mentioned desulfurization and denitrification equipment 60 can adopt the desulfurization and denitrification equipment in the existing technology, such as the SCR denitrification → desulfurization tower → electrostatic precipitator → chimney emission method in sequence, so as to further remove toxic gases in hazardous waste flue gas, reduce smoke dust emissions in flue gas and lower the emission temperature of flue gas.

[0041] The embodiment of the utility model utilizes the temperature change of high-temperature flue gas and adds SNCR denitrification in the waste heat boiler and the regenerative combustion equipment, so that NOx in the hazardous waste flue gas can be subjected to two-stage SNCR denitrification and one-stage SCR denitrification, thereby improving the denitrification efficiency and reducing the use of catalysts in the SCR denitrification process; by reasonably arranging the first flue in the waste heat boiler and forming a quasi-two-combustion chamber with the middle and upper space of the smelting furnace hearth, and adding regenerative combustion equipment, CO and VOC waste gases in the hazardous waste flue gas can be removed in two stages and complete combustion can be ensured; by bag collecting By adding a regenerative combustion device after the dust collector, dioxins remaining in the hazardous waste flue gas can be removed through three stages: combustion in a secondary combustion chamber, physical adsorption on activated carbon, and re-combustion in the regenerative combustion device. This also ensures that even if the subsequent flue gas temperature drops, it will be difficult to synthesize dioxins due to the lack of dioxin-forming catalysts (copper-containing substances) after the flue gas passes through the waste heat boiler, quenching tower, and bag filter for dust removal, thereby ensuring complete dioxin removal. By adopting the regenerative combustion device, waste gases containing calorific value, such as CO in the flue gas, can be used for secondary utilization of thermal energy resources, reducing fuel usage.

[0042] To sum up, the hazardous waste flue gas treatment system provided by the utility model can achieve multi-stage elimination of harmful components in hazardous waste flue gas by optimizing production equipment and process flow without increasing process flow and equipment conditions, so that the flue gas can meet emission standards. At the same time, it can reduce the use of production materials in the flue gas purification process and improve economic benefits.

[0043] Throughout this specification, reference to terms such as "one embodiment," "some embodiments," "examples," "specific examples," or "some examples" means that the specific features, structures, materials, or characteristics described in conjunction with that embodiment or example are included in at least one embodiment or example of the present invention. In this specification, schematic representations of the above terms do not necessarily refer to the same embodiment or example. Furthermore, the specific features, structures, materials, or characteristics described may be combined in any suitable manner in any one or more embodiments or examples.

[0044] The above-described embodiments merely represent several implementations of the present invention. While the descriptions are relatively specific and detailed, they should not be construed as limiting the scope of the present invention. It should be noted that a person skilled in the art would be able to make various modifications and improvements without departing from the spirit of the present invention, and these modifications and improvements fall within the scope of protection of the present invention. Therefore, the scope of protection of the present invention shall be determined by the appended claims.

Claims

1. A hazardous waste flue gas treatment system, characterized in that: The exhaust gas discharge direction includes a waste heat boiler, a quenching tower, a bag dust collector, a regenerative combustion device, and a desulfurization and denitrification device. The flue gas inlet of the waste heat boiler is connected to the flue gas outlet of the smelting furnace flue. The waste heat boiler, the quenching tower, the bag dust collector, the regenerative combustion device, and the desulfurization and denitrification device are connected by pipelines. The waste heat boiler is provided with at least a first flue, a second flue, and a third flue connected end to end and arranged in parallel. The centerline of the first flue coincides perpendicularly with the centerline of the flue gas outlet of the smelting furnace flue. A plurality of first SNCR denitrification reserved holes are provided in the area of ​​the second flue where the flue gas temperature is 1000°C ± 100°C. The regenerative combustion equipment comprises a regenerative chamber and a combustion chamber, wherein a plurality of second SNCR denitration reserved holes are provided in the combustion chamber.

2. The hazardous waste flue gas treatment system according to claim 1, characterized in that: The waste heat boiler is further provided with a fourth flue and a fifth flue arranged in parallel with the third flue, and the third flue, the fourth flue and the fifth flue are arranged end to end.

3. The hazardous waste flue gas treatment system according to claim 1, characterized in that: The water-cooled wall of the first flue is provided with a combustion protection zone.

4. The hazardous waste flue gas treatment system according to claim 1, characterized in that: The height of the first flue is not less than 10m, and the residence time of the flue gas in the first flue is not less than 2s.

5. The hazardous waste flue gas treatment system according to claim 1, characterized in that: The flue gas inlet of the waste heat boiler is connected to the flue gas outlet of the smelting furnace flue through an expansion joint.

6. The hazardous waste flue gas treatment system according to claim 1, characterized in that: A plurality of atomizing spray guns are provided on the upper portion of the quenching tower, and a plurality of activated carbon reserved holes are provided on the inner wall of the quenching tower.

7. The hazardous waste flue gas treatment system according to claim 1, characterized in that: A natural gas burner and a temperature feedback device are provided in the combustion chamber. The temperature feedback device can be used to adjust the amount of natural gas in the natural gas burner according to the temperature of the combustion chamber.

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