Pickling waste liquid treatment and waste heat recovery system

Abstract

This application provides a pickling waste liquid treatment and waste heat recovery system, belonging to the technical field of pickling waste liquid treatment in the metallurgical industry. The system includes a pickling waste liquid regeneration system and a tail gas waste heat recovery system. The pickling waste liquid regeneration system includes a spray roasting mechanism for roasting the pickling waste liquid and a regeneration mechanism for treating the flue gas output from the spray roasting mechanism. The tail gas waste heat recovery system includes a combustion fan and a tail gas heat exchanger connected to the tail gas output end of the regeneration mechanism. The combustion fan is connected to the tail gas heat exchanger through a combustion air input pipe, and the tail gas heat exchanger is connected to the spray roasting mechanism through a combustion air output pipe. Through this method, this application can efficiently treat the pickling waste liquid while recovering the waste heat from the generated high-temperature tail gas, and reuse the recovered waste heat in the spray roasting mechanism of the pickling waste liquid regeneration system, effectively improving energy utilization efficiency and economic benefits.

Description

Technical Field

[0001] This application relates to the field of pickling waste liquid treatment technology in the metallurgical industry, specifically to a pickling waste liquid treatment and waste heat recovery system. Background Technology

[0002] Pickling is a crucial step in the metallurgical industry, primarily used for metal surface treatment, and plays a key role in the pretreatment of various metal materials. However, pickling generates a large amount of waste liquid, which typically contains waste acid and heavy metals. If not effectively treated, this waste liquid can pose a serious threat to the environment. Therefore, it is necessary to effectively treat pickling waste liquid.

[0003] Existing methods for treating pickling waste typically involve roasting, resulting in high-temperature exhaust gases. Directly discharging these gases not only pollutes the environment but also wastes energy. Furthermore, current technologies have limitations in terms of processing efficiency and resource recovery. Therefore, it is necessary to design an improved pickling waste treatment and waste heat recovery system to address these issues. Summary of the Invention

[0004] In view of the technical problems existing in the background art, this application provides a pickling waste liquid treatment and waste heat recovery and utilization system. The system can efficiently treat pickling waste liquid and recover the waste heat in the high temperature tail gas generated by it, and reuse the recovered waste heat in the treatment process of pickling waste liquid, effectively improving the energy utilization rate.

[0005] This application provides a pickling waste liquid treatment and waste heat recovery system, including a pickling waste liquid regeneration system and a tail gas waste heat recovery system;

[0006] The pickling waste liquid regeneration system includes a spray roasting mechanism for roasting the pickling waste liquid and a regeneration mechanism for treating the flue gas output from the spray roasting mechanism.

[0007] The exhaust gas waste heat utilization system includes a combustion-supporting fan and an exhaust gas heat exchanger connected to the exhaust gas output end of the regeneration mechanism; the combustion-supporting fan is connected to the exhaust gas heat exchanger through a combustion-supporting air input pipe, and the exhaust gas heat exchanger is connected to the spray roasting mechanism through a combustion-supporting air output pipe.

[0008] In the technical solution of this application embodiment, by setting up an acid pickling waste liquid regeneration system, the acid pickling waste liquid can be spray-roasted, and the flue gas generated after roasting can be regenerated. While recovering useful resources, it can effectively avoid the pollution of the environment by the flue gas. On this basis, by setting up a tail gas waste heat utilization system, the waste heat of the tail gas discharged from the regeneration mechanism can be effectively recovered, and the recovered waste heat can be used to preheat the combustion air. The preheated combustion air can be used in the spray roasting process of the acid pickling waste liquid to provide heat for the spray pyrolysis process, thereby reducing the gas energy consumption required by the spray roasting mechanism, effectively improving energy utilization efficiency, and reducing the treatment cost of acid pickling waste liquid, resulting in a significant improvement in economic benefits.

[0009] In some embodiments, the exhaust gas heat exchanger includes a first channel and a second channel that are not interconnected; the first channel includes an exhaust gas inlet and an exhaust gas outlet, the exhaust gas inlet being connected to the exhaust gas output end of the regeneration mechanism; the second channel includes a combustion air inlet and a combustion air outlet, the combustion air inlet being connected to the combustion air input pipe, and the combustion air outlet being connected to the combustion air output pipe.

[0010] In this embodiment, by inputting the exhaust gas and combustion air into the exhaust gas heat exchanger through the first channel and the second channel respectively, heat exchange between the exhaust gas and the combustion air can be achieved while avoiding mixing between them. This allows the waste heat of the exhaust gas to be used to preheat the combustion air, thereby achieving effective utilization of the waste heat of the exhaust gas.

[0011] In some embodiments, the exhaust gas inlet and the combustion air outlet are located on the hot side of the exhaust gas heat exchanger, and the exhaust gas outlet and the combustion air inlet are located on the cold side of the exhaust gas heat exchanger.

[0012] In this embodiment, by placing the exhaust gas inlet and the combustion air outlet on the hot side and the exhaust gas outlet and the combustion air inlet on the cold side, the exhaust gas and combustion air can flow in opposite directions to improve the efficiency of heat exchange and further improve the utilization rate of heat.

[0013] In some embodiments, the spray roasting mechanism includes a roasting device, which includes a burner connected to a gas pipeline and a combustion air output pipeline, respectively.

[0014] In this embodiment, by connecting the combustion air output pipe to the burner, the preheated combustion air can be mixed with the gas for combustion, providing heat for the spray roasting process, while reducing the amount of gas used and effectively saving gas costs.

[0015] In some embodiments, the spray roasting mechanism further includes a pretreatment device, which includes a concentration unit and a dust removal unit; the inlet end of the concentration unit is connected to the pickling waste liquid input pipeline, and the concentrated liquid output end of the concentration unit is connected to the roasting device through the concentrated liquid delivery pipeline; the input end of the dust removal unit is connected to the flue gas output pipeline of the roasting device, and the output end of the dust removal unit is connected to the input end of the regeneration mechanism.

[0016] In this embodiment, by setting up a pretreatment device, the pickling waste liquid can be concentrated by the concentration unit and sprayed into the roasting device for roasting; the flue gas generated by roasting is then removed by the dust removal unit, and after dust removal, it can be recycled by the regeneration mechanism to recover the regenerated acid.

[0017] In some embodiments, the regeneration mechanism includes an absorption device, a cooling device, an oxidation device, and a denitrification device that are sequentially connected through a flue gas transmission pipe; the absorption device is connected to the flue gas output from the spray roasting mechanism, and the tail gas output end of the denitrification device is connected to the tail gas heat exchanger.

[0018] In this embodiment, by setting up a regeneration mechanism, the acid in the flue gas in the form of vapor can be absorbed by the absorption device and converted into regenerated acid for collection, so as to achieve effective utilization of resources. The flue gas absorbed by the absorption device is initially cooled by the cooling device and then oxidized by the oxidation device. Then, the flue gas is denitrified by the denitrification mechanism to ensure that the nitrogen oxides in the flue gas meet the emission standards. The exhaust gas discharged by the denitrification mechanism still has a high temperature. The exhaust gas waste heat utilization system can recover its waste heat, which can effectively improve the energy utilization rate.

[0019] In some embodiments, the regeneration mechanism further includes a cooling conduit for cooling the oxidation apparatus, wherein a cooler is disposed in the cooling conduit.

[0020] In this embodiment, since the operating temperature of the oxidation device affects its oxidation efficiency, cooling the oxidation device by setting up a cooling pipeline can effectively improve its oxidation efficiency, so as to efficiently oxidize nitrogen oxides in flue gas.

[0021] In some embodiments, the cooling pipeline includes a cooling water inlet pipe for cooling water to enter and a cooling water return pipe for cooling water to flow out; the cooling water inlet pipe includes a first branch pipe connecting the inlet end of the cooler and the oxidation device, and the cooling water return pipe is connected to the outlet end of the oxidation device through the cooler.

[0022] In this embodiment, the cooling water, after being cooled by the cooler, can enter the oxidation device through the first branch pipe to cool the oxidation device, thereby reducing its operating temperature and improving oxidation efficiency; the cooling water flowing through the oxidation device flows out through the outlet end and then flows back to the cooler through the cooling water return pipe, forming a cycle.

[0023] In some embodiments, the cooling water inlet pipe further includes a second branch pipe; one end of the second branch pipe is connected to the cooler, and the other end of the second branch pipe is connected to the flue gas transmission pipe between the cooling device and the oxidation device.

[0024] In this embodiment, by setting up a second branch pipe, some of the cooling water can be used to cool the flue gas entering the oxidation unit. This can achieve cooling by reducing both the temperature of the flue gas entering the oxidation unit and the temperature of the oxidation unit itself, thus further improving the cooling efficiency.

[0025] In some embodiments, the exhaust gas heat exchanger is a plate heat exchanger or a shell-and-tube heat exchanger.

[0026] The above description is only an overview of the technical solution of this application. In order to better understand the technical means of this application and to implement it in accordance with the contents of the specification, and to make the above and other objects, features and advantages of this application more obvious and understandable, the following are specific embodiments of this application. Attached Figure Description

[0027] To more clearly illustrate the technical solutions of this application, the accompanying drawings used in this application will be briefly described below. Obviously, the drawings described below are merely some embodiments of this application. For those skilled in the art, other drawings can be obtained from these drawings without any creative effort.

[0028] Figure 1 This is a schematic diagram of the pickling waste liquid treatment and waste heat recovery system provided in the embodiments of this application;

[0029] Figure 2 This is a schematic diagram showing the connection between the tail gas waste heat utilization system and the pickling waste regeneration system in the pickling waste liquid treatment and waste heat recovery system provided in the embodiments of this application.

[0030] Explanation of reference numerals in the attached drawings: 1. Pickling waste liquid regeneration system; 11. Calcination device; 111. Burner; 112. Gas pipeline; 12. Pretreatment device; 121. Pickling waste liquid input pipeline; 122. Concentrate conveying pipeline; 123. Flue gas output pipeline; 13. Absorption device; 131. Regenerated acid output pipeline; 14. Cooling device; 15. Oxidation device; 16. Denitrification device; 17. Cooler; 171. First branch pipe; 172. Second branch pipe; 173. Cooling water return pipe; 18. Flue gas transmission pipeline; 2. Waste heat utilization system for tail gas; 21. Combustion fan; 22. Tail gas heat exchanger; 23. Combustion air input pipeline; 24. Combustion air output pipeline. Detailed Implementation

[0031] The embodiments of the technical solution of this application will now be described in detail with reference to the accompanying drawings. These embodiments are only used to more clearly illustrate the technical solution of this application and are therefore merely examples, and should not be used to limit the scope of protection of this application.

[0032] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this application pertains; the terminology used herein is for the purpose of describing particular embodiments only and is not intended to limit the application; the terms “comprising” and “having”, and any variations thereof, in the specification, claims, and foregoing description of the drawings are intended to cover non-exclusive inclusion.

[0033] In the description of the embodiments of this application, technical terms such as "first" and "second" are used only to distinguish different objects and should not be construed as indicating or implying relative importance or implicitly specifying the number, specific order, or primary and secondary relationship of the indicated technical features. In the description of the embodiments of this application, "multiple" means two or more, unless otherwise explicitly defined.

[0034] In this document, the term "embodiment" means that a particular feature, structure, or characteristic described in connection with an embodiment may be included in at least one embodiment of this application. The appearance of this phrase in various places throughout the specification does not necessarily refer to the same embodiment, nor is it a separate or alternative embodiment mutually exclusive with other embodiments. It will be explicitly and implicitly understood by those skilled in the art that the embodiments described herein can be combined with other embodiments.

[0035] In the description of the embodiments of this application, the technical terms "center," "longitudinal," "lateral," "length," "width," "thickness," "upper," "lower," "front," "rear," "left," "right," "vertical," "horizontal," "top," "bottom," "inner," "outer," "clockwise," "counterclockwise," "axial," "radial," and "circumferential" indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. They are only for the convenience of describing the embodiments of this application and simplifying the description, and are not intended to indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limitations on the embodiments of this application.

[0036] In the description of the embodiments of this application, unless otherwise expressly specified and limited, technical terms such as "installation," "connection," "joining," and "fixing" should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral part; they can refer to a mechanical connection or an electrical connection; they can refer to a direct connection or an indirect connection through an intermediate medium; they can refer to the internal communication of two components or the interaction between two components. For those skilled in the art, the specific meaning of the above terms in the embodiments of this application can be understood according to the specific circumstances.

[0037] In order to efficiently treat pickling waste liquid and effectively recover and utilize the waste heat in the high-temperature exhaust gas generated, this application provides a pickling waste liquid treatment and waste heat recovery and utilization system. The system uses a pickling waste liquid regeneration system 1 to roast and regenerate the pickling waste liquid. At the same time, the waste heat recovery and utilization system uses the exhaust gas discharged from the pickling waste liquid regeneration system 1 to preheat the combustion air. The preheated combustion air is then used in the roasting of the pickling waste liquid, thereby achieving efficient energy utilization.

[0038] like Figure 1 As shown, this application provides a pickling waste liquid treatment and waste heat recovery system, including a pickling waste liquid regeneration system 1 and a tail gas waste heat recovery system 2.

[0039] The pickling waste liquid regeneration system 1 includes a spray roasting mechanism for roasting the pickling waste liquid and a regeneration mechanism for treating the flue gas output from the spray roasting mechanism.

[0040] The exhaust gas waste heat utilization system 2 includes a combustion-supporting blower 21 and an exhaust gas heat exchanger 22 connected to the exhaust gas output end of the regeneration mechanism; the combustion-supporting blower 21 is connected to the exhaust gas heat exchanger 22 through a combustion-supporting air input pipe 23, and the exhaust gas heat exchanger 22 is connected to the spray roasting mechanism through a combustion-supporting air output pipe 24.

[0041] Through the above methods, this embodiment of the application can utilize a spray roasting mechanism to treat pickling waste liquid by spray roasting, and utilize a regeneration mechanism to regenerate the flue gas after roasting, so as to recover regenerated acid and avoid generating pollutants. This improves resource utilization while avoiding environmental pollution. Furthermore, the waste heat recovery system 2 effectively recovers the waste heat from the exhaust gas discharged by the regeneration mechanism, and uses the recovered waste heat to preheat the combustion air. The preheated combustion air can be used in the spray roasting process of the pickling waste liquid, providing heat for the spray pyrolysis process, thereby reducing the gas energy consumption required by the spray roasting mechanism, effectively improving energy utilization efficiency, and reducing the treatment cost of pickling waste liquid. This significantly enhances economic benefits and has important practical significance for promoting the green transformation of the metallurgical industry and achieving sustainable development.

[0042] Further, in this embodiment, the exhaust gas heat exchanger 22 includes a first channel and a second channel that are not interconnected; the first channel includes an exhaust gas inlet and an exhaust gas outlet, the exhaust gas inlet being connected to the exhaust gas output end of the regeneration mechanism; the second channel includes a combustion air inlet and a combustion air outlet, the combustion air inlet being connected to the combustion air input pipe 23, and the combustion air outlet being connected to the combustion air output pipe 24. More preferably, the exhaust gas inlet and the combustion air outlet are located on the hot side of the exhaust gas heat exchanger 22, and the exhaust gas outlet and the combustion air inlet are located on the cold side of the exhaust gas heat exchanger 22.

[0043] In the above embodiments, "not interconnected" means that the gases within the channels do not mix, but heat exchange can occur between the two channels. This embodiment utilizes the exhaust gas heat exchanger 22 to preheat the combustion air using the waste heat of the exhaust gas, achieving efficient utilization of the exhaust gas waste heat. More specifically, the exhaust gas heat exchanger 22 can be selected as a plate heat exchanger or a shell-and-tube heat exchanger as needed.

[0044] Furthermore, please refer to the following: Figure 1-2 In this embodiment, the spray roasting mechanism includes a roasting device 11, which includes a burner 111. The burner 111 is connected to a gas pipeline 112 and a combustion air output pipeline 24, respectively. This configuration allows the combustion air to mix with the gas for combustion, providing heat for the roasting process. By utilizing the waste heat of the exhaust gas to preheat the combustion air, its temperature can be increased, resulting in better combustion. Compared to using ambient temperature combustion air, this effectively reduces the amount of gas required for the roasting process, saving energy and reducing gas costs, thus demonstrating high energy efficiency and economic benefits.

[0045] Furthermore, in this embodiment, the spray roasting mechanism further includes a pretreatment device 12, which includes a concentration unit and a dust removal unit. The inlet of the concentration unit is connected to the pickling waste liquid input pipe 121, and the concentrated liquid output of the concentration unit is connected to the roasting device 11 through the concentrated liquid conveying pipe 122. The input of the dust removal unit is connected to the flue gas output pipe 123 of the roasting device 11, and the output of the dust removal unit is connected to the input of the regeneration mechanism. This configuration allows the pickling waste liquid to be concentrated by the concentration unit before being sprayed into the roasting device 11, effectively avoiding the problem of long roasting time caused by excessive moisture in the pickling waste liquid, thus effectively shortening the required roasting time and further reducing energy consumption during the roasting process. After roasting, the generated flue gas not only contains acid vapors to be recovered but may also contain some dust. Treatment by the dust removal unit can prevent the dust from affecting subsequent processes. In the embodiments of this application, the concentration unit and the dust removal unit can be selected from existing acid concentration devices and conventional dust removal devices, as long as they can achieve the effects of concentration and dust removal. This application is not limited to these.

[0046] Furthermore, in this embodiment, the regeneration mechanism includes an absorption device 13, a cooling device 14, an oxidation device 15, and a denitrification device 16, which are sequentially connected through a flue gas transmission pipe 18. The absorption device 13 is connected to the flue gas output from the spray roasting mechanism, and the tail gas output end of the denitrification device 16 is connected to the tail gas heat exchanger 22. This configuration allows the absorption device 13 to absorb acids in the flue gas in vapor form. For example, when the pickling waste liquid contains hydrochloric acid, roasting can cause the hydrochloric acid to volatilize at high temperatures to form hydrogen chloride gas. After absorption by the absorption device 13, regenerated acid can be formed and output through the regenerated acid output pipe 131, thus realizing the recovery and utilization of waste acid. Since the flue gas may also contain nitrogen oxides, after absorbing the acid in the flue gas, it is necessary to oxidize it. However, the oxidation device 15 is not suitable for use at high temperatures. This application provides a cooling device 14 before the oxidation device 15 to pre-cool the flue gas, ensuring the normal operation of the oxidation device 15. After the nitrogen oxides in the flue gas are oxidized by the oxidation device 15, they still need to be treated by the denitrification device 16 to prevent them from polluting the air if directly emitted. Because the catalytic reaction in the denitrification process of the denitrification device 16 raises the temperature of the flue gas, even with a cooling device 14 installed before oxidation, the exhaust gas discharged after treatment by the denitrification device 16 still has a high temperature (180~250℃), requiring waste heat utilization. In this embodiment, the absorption device 13, cooling device 14, oxidation device 15, and denitrification device 16 can all be existing conventional devices that achieve the corresponding functions; this application is not limited to these.

[0047] Furthermore, please refer to the following: Figure 1-2In this embodiment, to further reduce the operating temperature of the oxidation device 15 and improve its oxidation efficiency, the regeneration mechanism further includes a cooling pipeline for cooling the oxidation device 15, and a cooler 17 is provided in the cooling pipeline. Specifically, the cooling pipeline includes a cooling water inlet pipe for cooling water to enter and a cooling water return pipe 173 for cooling water to flow out; the cooling water inlet pipe includes a first branch pipe 171 connecting the cooler 17 and the inlet end of the oxidation device 15, and the cooling water return pipe 173 is connected to the outlet end of the oxidation device 15 through the cooler 17; more preferably, the cooling water inlet pipe further includes a second branch pipe 172; one end of the second branch pipe 172 is connected to the cooler 17, and the other end of the second branch pipe 172 is connected to the flue gas transmission pipeline 18 between the cooling device 14 and the oxidation device 15. With this configuration, after the coolant enters the cooler 17 and is cooled, it can be output from the first branch pipe 171 and the second branch pipe 172 respectively. Part of it is used to cool the flue gas entering the oxidation unit 15, and the other part is used to directly cool the oxidation unit 15, thereby effectively improving the cooling efficiency of the oxidation unit 15. The circulating liquid in the two branch pipes can be output again through the cooling water return pipe 173 after entering the oxidation unit 15. Appropriate flow valves can be installed in the first branch pipe 171 and the second branch pipe 172 as needed to regulate the flow rate of the circulating liquid in the first branch pipe 171 and the second branch pipe 172.

[0048] The following describes the usage method and measured results of the pickling waste liquid treatment and waste heat recovery system provided in this application, with reference to specific embodiments.

[0049] Example 1

[0050] This embodiment provides a system for treating pickling waste liquid and recovering waste heat, the structural diagram of which is shown below. Figure 1-2 As shown, it includes a pickling waste liquid regeneration system 1 and a tail gas waste heat utilization system 2. The tail gas waste heat utilization system 2 includes a combustion-supporting fan 21 and a tail gas heat exchanger 22 connected to the tail gas output end of the regeneration mechanism. The combustion-supporting fan 21 is connected to the tail gas heat exchanger 22 via a combustion-supporting air input pipe 23, and the tail gas heat exchanger 22 is connected to the spray roasting mechanism via a combustion-supporting air output pipe 24.

[0051] In this embodiment, the spray roasting mechanism includes a roasting device 11 and a pretreatment device 12; wherein, the roasting device 11 includes a burner 111, which is connected to a gas pipeline 112 and a combustion air output pipeline 24 respectively; the pretreatment device 12 includes a concentration unit and a dust removal unit; the inlet end of the concentration unit is connected to the pickling waste liquid input pipeline 121, and the concentrated liquid output end of the concentration unit is connected to the roasting device 11 through the concentrated liquid conveying pipeline 122; the input end of the dust removal unit is connected to the flue gas output pipeline 123 of the roasting device 11, and the output end of the dust removal unit is connected to the input end of the regeneration mechanism.

[0052] The regeneration mechanism includes an absorption device 13, a cooling device 14, an oxidation device 15, and a denitrification device 16, which are connected in sequence through a flue gas transmission pipe 18. The absorption device 13 is connected to the flue gas output from the spray roasting mechanism, and the tail gas output end of the denitrification device 16 is connected to the tail gas heat exchanger 22. The regeneration mechanism also includes a cooling pipeline for cooling the oxidation device 15, in which a cooler 17 is installed. The cooling pipeline includes a cooling water inlet pipe for cooling water to enter and a cooling water return pipe 173 for cooling water to flow out. The cooling water return pipe 173 is connected to the outlet end of the oxidation device 15 through the cooler 17. The cooling water inlet pipe includes a first branch pipe 171 and a second branch pipe 172. The two ends of the first branch pipe 171 are connected to the cooler 17 and the oxidation device 15, respectively. One end of the second branch pipe 172 is connected to the cooler 17, and the other end is connected to the flue gas transmission pipe 18 between the cooling device 14 and the oxidation device 15.

[0053] The exhaust gas heat exchanger 22 includes a first channel and a second channel that are not interconnected. The first channel includes an exhaust gas inlet and an exhaust gas outlet, with the exhaust gas inlet connected to the exhaust gas output end of the regeneration mechanism. The second channel includes a combustion air inlet and a combustion air outlet, with the combustion air inlet connected to the combustion air input pipe 23 and the combustion air outlet connected to the combustion air output pipe 24. More preferably, the exhaust gas inlet and the combustion air outlet are located on the hot side of the exhaust gas heat exchanger 22, and the exhaust gas outlet and the combustion air inlet are located on the cold side of the exhaust gas heat exchanger 22.

[0054] When using the pickling waste liquid treatment and waste heat recovery system provided in this embodiment, the pickling waste liquid is fed into the pretreatment device 12 through the pickling waste liquid input pipe 121. After being concentrated by the concentration unit, it is sprayed into the roasting device 11, where it undergoes roasting under the action of the burner 111. The generated flue gas is filtered by the dust removal unit and then absorbed in the absorption device 13. The collected regenerated acid is output through the regenerated acid output pipe 131. The remaining flue gas is cooled by the cooling device 14 and then enters the oxidation device 15 for oxidation treatment. The oxidized flue gas then enters the denitrification device 16 for denitrification treatment, generating exhaust gas with waste heat. This exhaust gas enters the exhaust gas heat exchanger 22. At the same time, the combustion fan 21 pressurizes the cold air and delivers it to the exhaust gas heat exchanger 22, using the waste heat of the exhaust gas to preheat the combustion air. The preheated combustion air is then delivered to the burner 111 to mix and burn with the fuel gas, providing heat for the roasting device 11.

[0055] After multiple tests and verifications, based on the pickling waste liquid treatment and waste heat recovery system provided in this application, the temperature range at the tail gas inlet of the tail gas heat exchanger 22 is typically 180~250℃, the tail gas flow rate is typically 3500~15000 Nm³ / h, and the tail gas temperature discharged from the outlet after heat exchange is 80~120℃, showing a significant decrease in tail gas temperature. The temperature of the combustion air entering the tail gas heat exchanger 22 is typically 10~30℃, and the preferred flow rate range is 3000~12000 Nm³ / h. After preheating, the temperature range of the combustion air output from the outlet is 100~160℃, showing a significant increase in combustion air temperature. Compared to conventional systems that do not preheat the combustion air, the pickling waste liquid treatment and waste heat recovery system provided in this application can save approximately 4%~10% of fuel gas consumption by preheating the combustion air, effectively improving energy utilization efficiency and reducing the treatment cost of pickling waste liquid, resulting in a significant improvement in economic benefits.

[0056] In summary, this application provides a pickling waste liquid treatment and waste heat recovery system, belonging to the technical field of pickling waste liquid treatment in the metallurgical industry. The system includes a pickling waste liquid regeneration system 1 and a tail gas waste heat recovery system 2. The pickling waste liquid regeneration system 1 includes a spray roasting mechanism for roasting the pickling waste liquid and a regeneration mechanism for treating the flue gas output from the spray roasting mechanism. The tail gas waste heat recovery system 2 includes a combustion fan 21 and a tail gas heat exchanger 22 connected to the tail gas output end of the regeneration mechanism. The combustion fan 21 is connected to the tail gas heat exchanger 22 via a combustion air input pipe 23, and the tail gas heat exchanger 22 is connected to the spray roasting mechanism via a combustion air output pipe 24. Through this method, this application can efficiently treat the pickling waste liquid while recovering the waste heat from the generated high-temperature tail gas, and reuse the recovered waste heat in the spray roasting mechanism of the pickling waste liquid regeneration system, effectively improving energy utilization efficiency and economic benefits.

[0057] It should be noted that this application is not limited to the above-described embodiments. The above embodiments are merely examples, and any embodiments with the same structure and effect as the technical concept within the scope of this application are included in the technical scope of this application. Furthermore, various modifications that can be conceived by those skilled in the art to the embodiments, and other ways of constructing by combining some of the constituent elements of the embodiments, without departing from the spirit of this application, are also included in the scope of this application.

Claims

1. A system for treating pickling waste liquid and recovering waste heat, characterized in that, This includes a pickling waste liquid regeneration system and a tail gas waste heat utilization system; The pickling waste liquid regeneration system includes a spray roasting mechanism for roasting the pickling waste liquid and a regeneration mechanism for treating the flue gas output from the spray roasting mechanism. The exhaust gas waste heat utilization system includes a combustion-supporting fan and an exhaust gas heat exchanger connected to the exhaust gas output end of the regeneration mechanism; the combustion-supporting fan is connected to the exhaust gas heat exchanger through a combustion-supporting air input pipe, and the exhaust gas heat exchanger is connected to the spray roasting mechanism through a combustion-supporting air output pipe.

2. The pickling waste liquid treatment and waste heat recovery system according to claim 1, characterized in that, The exhaust gas heat exchanger includes a first channel and a second channel that are not interconnected; the first channel includes an exhaust gas inlet and an exhaust gas outlet, the exhaust gas inlet being connected to the exhaust gas output end of the regeneration mechanism; the second channel includes a combustion air inlet and a combustion air outlet, the combustion air inlet being connected to the combustion air input pipe, and the combustion air outlet being connected to the combustion air output pipe.

3. The pickling waste liquid treatment and waste heat recovery system according to claim 2, characterized in that, The exhaust gas inlet and the combustion air outlet are located on the hot side of the exhaust gas heat exchanger, while the exhaust gas outlet and the combustion air inlet are located on the cold side of the exhaust gas heat exchanger.

4. The pickling waste liquid treatment and waste heat recovery system according to claim 1, characterized in that, The spray roasting mechanism includes a roasting device, which includes a burner connected to a gas pipeline and a combustion air output pipeline.

5. The pickling waste liquid treatment and waste heat recovery system according to claim 4, characterized in that, The spray roasting mechanism also includes a pretreatment device, which includes a concentration unit and a dust removal unit. The inlet of the concentration unit is connected to the pickling waste liquid input pipeline, and the concentrated liquid output of the concentration unit is connected to the roasting device through the concentrated liquid delivery pipeline. The input of the dust removal unit is connected to the flue gas output pipeline of the roasting device, and the output of the dust removal unit is connected to the input of the regeneration mechanism.

6. The pickling waste liquid treatment and waste heat recovery system according to claim 1, characterized in that, The regeneration mechanism includes an absorption device, a cooling device, an oxidation device, and a denitrification device that are connected in sequence through a flue gas transmission pipeline; the absorption device is connected to the flue gas output from the spray roasting mechanism, and the tail gas output end of the denitrification device is connected to the tail gas heat exchanger.

7. The pickling waste liquid treatment and waste heat recovery system according to claim 6, characterized in that, The regeneration mechanism also includes a cooling pipe for cooling the oxidation device, and a cooler is provided in the cooling pipe.

8. The pickling waste liquid treatment and waste heat recovery system according to claim 7, characterized in that, The cooling pipeline includes a cooling water inlet pipe for cooling water to enter and a cooling water return pipe for cooling water to flow out; the cooling water inlet pipe includes a first branch pipe connecting the inlet end of the cooler and the oxidation device, and the cooling water return pipe is connected to the outlet end of the oxidation device through the cooler.

9. The pickling waste liquid treatment and waste heat recovery system according to claim 8, characterized in that, The cooling water inlet pipe also includes a second branch pipe; one end of the second branch pipe is connected to the cooler, and the other end of the second branch pipe is connected to the flue gas transmission pipe between the cooling device and the oxidation device.

10. The pickling waste liquid treatment and waste heat recovery system according to claim 1, characterized in that, The exhaust gas heat exchanger is a plate heat exchanger or a shell-and-tube heat exchanger.

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