Galvanized wire annealing furnace flue gas denitration device

Abstract

The utility model relates to a flue gas denitration device for a galvanized wire annealing furnace. The flue gas denitration device comprises an SCR (Selective Catalytic Reduction) catalytic reactor, a reducing agent storage system, a reducing agent injection system, a compressed air system, a flue gas monitoring system and an automatic control system, by adopting the in-situ online NOx sensor and the flow velocity type flow meter, the content and the flow of the nitric oxide in the flue gas can be accurately monitored in real time. The digital metering pump is used for accurately controlling the spraying amount of the reducing agent, the reducing agent mixed with the compressed air is atomized and sprayed into the flue gas through the sprayer, and the denitration reaction is effectively promoted. And the automatic control system automatically adjusts injection parameters according to flue gas monitoring data, so that the denitration efficiency is maximized, the consumption of a reducing agent is reduced, and the operation cost is reduced.

Description

Technical Field

[0001] This application belongs to the field of flue gas denitrification technology, and specifically relates to a flue gas denitrification device for annealing furnaces in galvanizing lines. Background Technology

[0002] Currently, with the increasing awareness of human ecology and the increasingly stringent environmental regulations, the content of nitrogen oxides (NOx) in the flue gas emitted from the annealing furnace of industrial galvanizing lines has become an important environmental indicator of concern.

[0003] Currently, annealing is a key process in hot-dip galvanizing production lines, directly determining the performance and quality of the galvanized sheets produced. The annealing furnace in a galvanizing line can reach temperatures as high as 900℃. Natural gas or a mixture of coal gas and air is typically used as fuel, burned in radiant tube burners, and then discharged as flue gas through flue pipes.

[0004] The basic principle of selective catalytic reduction (SCR) denitrification is to introduce a reducing agent (usually urea solution, ammonia water, or liquid ammonia) into the flue gas, and then, under the action of a catalyst, reduce NOx in the flue gas to harmless nitrogen (N2) and water vapor (H2O). Due to its advantages such as good performance, no emissions of pollutants, and stable and reliable operation, SCR denitrification technology has been widely used in the field of power boilers. However, its application in the treatment of flue gas from annealing furnaces in galvanizing lines is still in its early stages.

[0005] Compared to power plant boilers, the operation of annealing furnaces in galvanizing lines requires precise control of the annealing temperature and atmosphere in the furnace based on the different thicknesses and types of steel plates. Therefore, the flue gas flow and temperature fluctuate significantly during operation. When SCR denitrification devices, which are widely used in power plants, are directly applied to denitrification in galvanizing line annealing furnaces, problems such as delayed nitrogen oxide detection signals, inaccurate flue gas flow detection, excessive fluctuations in liquid injection volume, and severe ammonia escape often occur during operation, resulting in reduced denitrification efficiency and increased operating costs.

[0006] Controlling nitrogen oxides (NOx) in the flue gas emitted from annealing furnaces in galvanizing lines has become particularly important. However, the application of selective catalytic reduction (SCR) technology in galvanizing line annealing furnaces faces challenges such as large fluctuations in flue gas flow and temperature, delayed NOx detection, and inaccurate control of reducing agent injection, resulting in low denitrification efficiency and increased operating costs. Summary of the Invention

[0007] The purpose of this application is to provide a denitrification device for flue gas from a galvanizing line annealing furnace. By improving the nitrogen oxide detection method, the flue gas flow detection method, and introducing a digital metering pump, this device solves the problems in the prior art, improves denitrification efficiency, and reduces operating costs.

[0008] One of the improvements is that in-situ online detection technology is used to replace the traditional sampling method, enabling real-time monitoring of nitrogen oxides, avoiding data lag, and improving detection sensitivity.

[0009] The second improvement is to improve the response speed and accuracy of flue gas flow detection by using a velocity-type flow meter instead of a resistance-type flow meter, thus ensuring accurate adjustment of the reducing agent injection amount based on the real-time flue gas flow.

[0010] The third improvement is the introduction of a digital metering pump to replace the traditional mechanical flow pump, which enables precise control of the reducing agent flow rate. The flow rate adjustment ratio can reach 1:1000, effectively reducing the consumption of reducing agent and lowering operating costs.

[0011] The technical improvements of this application will be described in more detail below:

[0012] (1) The core of this application lies in the use of in-situ online detection technology, which achieves real-time monitoring of nitrogen oxides in flue gas by installing NOx sensors (in some embodiments, corresponding to NOx sensor 5 before denitrification and NOx sensor 6 after denitrification) in the flue gas emission duct. This detection method avoids the lag of traditional sampling methods and improves the real-time performance and accuracy of detection.

[0013] (2) In terms of flue gas flow detection, this application uses a velocity-type flow meter (corresponding to flue gas flow sensor 7 in some embodiments) instead of a traditional resistance-type flow meter. The velocity-type flow meter has a faster response speed and higher measurement accuracy, and can monitor flue gas flow accurately in real time, providing accurate data support for the reducing agent injection system.

[0014] (3) This application also introduces a digital metering pump (corresponding to flow pump 8 in some embodiments) as the core component of the reducing agent injection system for controlling the flow rate of the reducing agent (urea solution, ammonia water or liquid ammonia). The introduction of the digital metering pump enables the adjustment ratio of the reducing agent flow rate to reach 1:1000, which greatly improves the adjustment accuracy of the reducing agent flow rate, thereby reducing the consumption of reducing agent and lowering the operating cost of the denitrification device.

[0015] (4) The design of the reducing agent injection system (corresponding to reducing agent injection system 3 in some embodiments) is also an important feature of this application. This system consists of a digital metering pump (corresponding to flow pump 8 in some embodiments), an injector (corresponding to injector 9 in some embodiments), and their auxiliary accessories. The injector is located upstream of the SCR catalytic reactor (corresponding to SCR catalytic reactor 1 in some embodiments) and is responsible for atomizing and uniformly injecting the reducing agent delivered by the digital metering pump into the flue gas after mixing with compressed air. This design ensures thorough mixing of the reducing agent and the flue gas, improving the denitrification efficiency.

[0016] (5) A compressed air system (corresponding to compressed air system 4 in some embodiments) provides power to the reducing agent injection system. This system consists of a compressed air tank, compressed air pipelines, and their accessories, providing compressed air at 0.4-0.6 MPa. The compressed air is used not only to atomize the reducing agent but also to increase the contact area between the reducing agent and the flue gas, thereby improving the efficiency of the denitrification reaction.

[0017] The technical solution of this application will be described in detail below.

[0018] This application provides a denitrification device for flue gas from an annealing furnace in a galvanizing line, characterized in that it includes an SCR catalytic reactor (1), a reducing agent storage system (2), a reducing agent injection system (3), a compressed air system (4), and a flue gas monitoring system and an automatic control system composed of sensors.

[0019] In some embodiments, the flue gas monitoring system includes a pre-denitrification NOx sensor (5), a post-denitrification NOx sensor (6), and a flue gas flow sensor (7), wherein the pre-denitrification and post-denitrification NOx sensors are used to detect nitrogen oxides in situ online.

[0020] In some embodiments, the reducing agent injection system (3) is characterized by comprising a digital metering pump (8), an injector (9), and its accessories, wherein the digital metering pump is used to control the flow rate of the reducing agent. The accessories of the injector refer to components that can work with the injector to ensure that the reducing agent is injected into the reactor in an appropriate manner and dosage, commonly including but not limited to: nozzles, pipes and fittings, valves, filters, pressure gauges and flow meters, supports and fixing devices, etc.

[0021] In some embodiments, the flow rate adjustment ratio of the digital metering pump is 1:1000.

[0022] In some embodiments, the compressed air system (4) is used to provide compressed air at a pressure of 0.4-0.6 MPa to aid in the atomization and injection of the reducing agent.

[0023] In some embodiments, the flue gas flow sensor (7) is a flow velocity type flow meter to monitor the flue gas flow in real time and accurately, providing data support for adjusting the amount of reducing agent injected.

[0024] In some embodiments, the reducing agent storage system (2) is equipped with containers and accessories for storing urea solution, ammonia or liquid ammonia for use by the reducing agent injection system.

[0025] The accessories for containers of ammonia water or liquid ammonia refer to the accessories that can ensure the safe storage, stable supply and safety of ammonia water or liquid ammonia during use. Common accessories include, but are not limited to: safety valves, pressure gauges, level gauges, thermometers, leak detectors, feed pumps or transfer pumps, pipes and valves, etc.

[0026] In some embodiments, the automatic control system can automatically adjust the operating parameters of the digital metering pump and the injection frequency and quantity of the injector based on real-time data provided by the flue gas monitoring system to achieve optimal denitrification effect.

[0027] In some embodiments, the SCR catalytic reactor (1) is equipped with a high-efficiency catalyst module for catalytically reacting the reducing agent with NOx in the flue gas to generate harmless nitrogen and water vapor.

[0028] This application also provides a method for using a denitrification device for flue gas from a galvanizing line annealing furnace, characterized by comprising the following steps:

[0029] a) Use an in-situ online NOx sensor to monitor the nitrogen oxide content in flue gas in real time;

[0030] b) Monitor flue gas flow rate in real time using a velocity-type flow meter;

[0031] c) Based on the monitored nitrogen oxide content and flue gas flow data, the automatic control system adjusts the operating parameters of the digital metering pump to precisely control the amount of reducing agent injected.

[0032] d) The reducing agent is mixed with compressed air and then atomized and sprayed into the flue gas through an injector;

[0033] e) In the SCR catalytic reactor, the atomized reducing agent reacts with NOx in the flue gas to generate harmless nitrogen (N2) and water vapor (H2O), thereby achieving the purpose of denitrification.

[0034] It is hereby stated that, apart from this invention, existing mature technologies can be used for denitrification catalysts, pipeline valves, etc., and will not be elaborated here. Attached Figure Description

[0035] Figure 1 Schematic diagram of the denitrification device for flue gas from the annealing furnace in a galvanizing line. Detailed Implementation

[0036] Appendix Figure 1 The diagram shown is a schematic of a novel flue gas denitrification device for a galvanizing line annealing furnace according to the present invention.

[0037] The denitrification device mainly includes an SCR catalytic reactor (1), a reducing agent storage system (2), a reducing agent injection system (3), a compressed air system (4), a flue gas monitoring system composed of sensors, and an automatic control system. The SCR catalytic reactor contains a denitrification catalyst module (1); the reducing agent storage system consists of a urea solution tank and its accessories (2); the reducing agent injection system consists of a flow pump (8), an injector (9), a reducing agent pipeline and its accessories (3); the compressed air system consists of a compressed air storage tank and compressed air pipeline and its accessories (4); the flue gas monitoring system consists of a NOx sensor before denitrification (5), a NOx sensor after denitrification (6), a flue gas flow sensor (7), etc., and the monitoring data is transmitted to the automatic control system.

[0038] Example 1: In this example, urea solution is used as a reducing agent. An in-situ online NOx sensor monitors the nitrogen oxide content in the flue gas, a flow rate meter monitors the flue gas flow rate in real time, and a digital metering pump precisely controls the injection volume of the urea solution. The urea solution is atomized by an injector and injected into the flue gas under the action of compressed air. In the SCR catalytic reactor, it reacts with NOx, effectively converting it into nitrogen and water vapor, thereby achieving denitrification.

[0039] Example 2: Based on Example 1, this example uses ammonia as a reducing agent. The storage and injection system for ammonia is the same as that for urea solution, but considering the physical properties of ammonia, the design of the injector was adjusted accordingly to ensure that the ammonia can be effectively atomized and fully mixed with the flue gas. Similarly, through monitoring by an in-situ online NOx sensor and a flow rate meter, a digital metering pump precisely controls the injection volume of ammonia to achieve efficient denitrification.

[0040] Example 3: This example uses liquid ammonia as a reducing agent. Since the storage and usage conditions of liquid ammonia differ from those of urea solution and ammonia water, the reducing agent storage system and injection system were specially designed. Liquid ammonia is delivered to the injection system through a dedicated safety pipeline. Under the precise control of a digital metering pump, it is mixed with compressed air and then atomized and sprayed into the flue gas through injectors. Monitoring by in-situ online NOx sensors and flow rate meters ensures the high efficiency and safety of the denitrification process.

[0041] Example 4: This example further optimizes the automatic control system based on the previous three examples. The system can receive real-time data from NOx sensors before and after denitrification and from flue gas flow sensors. Through advanced algorithms, it automatically adjusts the operating parameters of the digital metering pump, as well as the injection frequency and volume of the injectors, ensuring optimal denitrification performance even with fluctuations in flue gas flow and NOx concentration. Furthermore, the automatic control system also features fault diagnosis and alarm functions, enabling timely detection of abnormalities in system operation and prompting operators for handling via the control interface, thus improving system stability and safety.

[0042] Beneficial effects

[0043] (1) Effectively improve denitrification efficiency: By adopting in-situ online detection technology and flow rate meter, this application can monitor the NOx content and flow rate in flue gas in real time and accurately. Combined with digital metering pump to precisely control the amount of reducing agent injected, the denitrification reaction is fully carried out, thereby significantly improving the denitrification efficiency.

[0044] (2) Significantly reduced operating costs: The introduction of digital metering pumps allows for precise control of the amount of reducing agent injected, avoiding excessive use of reducing agent, thereby reducing material consumption and lowering operating costs. At the same time, improved denitrification efficiency also means reducing potential environmental penalties for failing to meet denitrification standards.

[0045] (3) Maintaining environmental friendliness: This application reduces ammonia escape by optimizing the denitrification process, thus avoiding secondary pollution to the environment. Simultaneously, the efficient denitrification process reduces nitrogen oxide emissions, contributing to improved air quality and having a positive impact on environmental protection. Furthermore, by precisely controlling the use of reducing agents, the consumption of chemical substances is reduced, further minimizing the environmental impact.

[0046] (4) Wide applicability: This application has broad application prospects and important practical value in the field of industrial flue gas treatment.

[0047] Although embodiments of the invention have been shown and described, it will be understood by those skilled in the art that various changes, modifications, substitutions and alterations can be made to these embodiments without departing from the principles and spirit of the invention.

[0048] It should be noted that, in this document, relational terms such as "first" and "second" are used only to distinguish one entity or operation from another, and do not necessarily require or imply any such actual relationship or order between these entities or operations. Furthermore, the terms "comprising," "including," or any other variations thereof are intended to cover non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements includes not only those elements but also other elements not expressly listed, or elements inherent to such process, method, article, or apparatus.

Claims

1. A denitrification device for flue gas from an annealing furnace in a galvanizing line, characterized in that, It includes an SCR catalytic reactor (1), a reducing agent storage system (2), a reducing agent injection system (3), a compressed air system (4), and a flue gas monitoring and automatic control system composed of sensors; The flue gas monitoring system includes a NOx sensor before denitrification (5), a NOx sensor after denitrification (6), and a flue gas flow sensor (7), wherein the NOx sensors before and after denitrification adopt an in-situ online detection method for nitrogen oxides; The reducing agent injection system (3) includes a digital metering pump (8), an injector (9) and its accessories, wherein the digital metering pump is used to control the flow rate of the reducing agent.

2. The denitrification device for annealing furnace gas in galvanizing line according to claim 1, characterized in that, The flow rate adjustment ratio of the digital metering pump is 1:1000.

3. The denitrification device for annealing furnace gas in galvanizing line according to claim 1, characterized in that, The compressed air system (4) is used to provide compressed air at a pressure of 0.4-0.6 MPa.

4. The denitrification device for annealing furnace gas in galvanizing line according to claim 1, characterized in that, The flue gas flow sensor (7) is a velocity-type flow meter.

5. The denitrification device for annealing furnace gas in galvanizing line according to claim 1, characterized in that, The reducing agent storage system (2) is equipped with containers and accessories for storing urea solution, ammonia or liquid ammonia.

6. The denitrification device for annealing furnace gas in galvanizing line according to claim 1, characterized in that, The SCR catalytic reactor (1) is equipped with a high-efficiency catalyst module.

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