Equipment for treating nitric oxide in flue gas of heat treatment workshop and use method of equipment

Abstract

According to the treatment equipment for the nitric oxide in the flue gas of the heat treatment workshop and the using method of the treatment equipment, switching of four modes of normal operation, debugging, surpassing and pipe emptying can be achieved through opening and closing of a front baffle valve and a rear baffle valve and gear switching of a four-way reversing valve; therefore, equipment debugging can be carried out under the conditions of flue gas catalytic reduction treatment and non-stop of a heat treatment furnace, and the concentration of nitrogen oxide in a room is improved, so that switching use under four scenes such as detection of the catalytic reduction effect of an SCR catalytic reduction device during debugging, rapid emptying of flue gas in a pipeline and maintenance of equipment is realized.

Description

Technical Field

[0001] The present invention relates to the technical field of flue gas denitration equipment, and in particular to a device for treating nitrogen oxides in flue gas of a heat treatment workshop and a method for using the device. Background Art

[0002] Heat treatment workshops play an important role in the metal processing process, improving the mechanical and physical properties of materials through processes such as annealing, quenching, and tempering. However, these high-temperature treatment processes usually emit fumes containing nitrogen oxides (NOx), causing serious pollution to the environment. Nitrogen oxides are a major type of air pollutant that can form smog, acid rain, and photochemical smog, causing harm to human health and the ecosystem.

[0003] At present, the commonly used technology for the treatment of nitrogen oxides in flue gas from heat treatment workshops is selective catalytic reduction (SCR). Selective catalytic reduction technology (SCR) is mainly used for the treatment of nitrogen oxides in flue gas. Under the action of the catalyst, when the exhaust temperature is between 300℃ and 450℃, urea, a reducing agent, is sprayed into the flue gas to reduce NOx in the flue gas to N2 and H2O. The catalyst adopts a vanadium-based or molecular sieve configuration coated on the surface of honeycomb ceramics, with a 200-300 mesh structure, an air velocity of up to 15,000 h-1, and a conversion rate of more than 90%.

[0004] Existing flue gas treatment equipment usually collects flue gas directly into the SCR catalytic reduction device and discharges it outdoors after treatment. This type of flue gas treatment equipment needs to be installed and debugged or the pipeline cleaning and maintenance is carried out when the heat treatment furnace in the workshop is shut down. The actual situation is that each time the heat treatment furnace heats up, it consumes a lot of energy, so it usually works continuously for 24 hours. The flue gas treatment equipment needs to be regularly cleaned, repaired and debugged to be stable before it can effectively treat nitrogen oxides in the flue gas to meet the emission standards.

[0005] Therefore, developing an economical, efficient, stable and reliable nitrogen oxide treatment equipment can truly solve the problem of flue gas treatment in heat treatment workshops. Summary of the invention

[0006] The object of the present invention is to provide a device for treating nitrogen oxides in flue gas in a heat treatment workshop and a method for using the same, so as to solve the problem that the existing flue gas treatment equipment cannot complete equipment cleaning, maintenance and debugging when the heat treatment furnace is working continuously.

[0007] In order to solve the above technical problems, the present invention provides a device for treating nitrogen oxides in flue gas of a heat treatment workshop, comprising: A main smoke pipe, in which smoke generated by multiple heat treatment furnaces in the heat treatment workshop is collected and flows; An SCR catalytic reduction device, wherein the SCR catalytic reduction device is connected to the main smoke pipe via a smoke guide pipe; a fan, disposed between the SCR catalytic reduction device and the main smoke pipe, so as to introduce the smoke in the main smoke pipe into the SCR catalytic reduction device; A front baffle valve is installed on the smoke guide pipe between the SCR catalytic reduction device and the main smoke pipe, and is used to control the on-off of smoke in the smoke guide pipe; A four-way reversing valve, wherein the four-way reversing valve has four smoke pipe interfaces, the first smoke pipe interface is connected to the main smoke pipe, the second smoke pipe interface is connected to the rear end smoke guide pipe of the SCR catalytic reduction device, the third smoke pipe interface is connected to the outdoor exhaust pipe, and the fourth smoke pipe interface is connected to the indoor exhaust pipe; The four-way reversing valve has at least two gears, and various operation modes of the nitrogen oxide treatment equipment can be realized by switching different gears.

[0008] Preferably, the four-way reversing valve comprises a cylindrical valve body, a side wall of which is provided with four smoke pipe interfaces communicating with the inner cavity of the cylindrical valve body, and a reversing valve plate is provided inside the cylindrical valve body, and the middle of the reversing valve plate is rotatably connected with the cylindrical valve body through a driving shaft; The four-way reversing valve is also equipped with a driving cylinder, and the telescopic rod of the driving cylinder is connected to the driving shaft through a crank connecting rod. As the piston rod of the driving cylinder is extended and retracted, the crank connecting rod drives the driving shaft and the reversing valve plate connected to the driving shaft to rotate, thereby switching the different gears of the four-way reversing valve.

[0009] Preferably, the four-way reversing valve has two gears, namely gear A and gear B; One of the smoke pipe interfaces of the four-way reversing valve is always connected to the rear end smoke guide pipe of the SCR catalytic reduction device, and the reversing valve plate rotates 90 degrees under the action of the driving cylinder, switching between gear A and gear B, thereby connecting two of the other three smoke pipe interfaces.

[0010] Preferably, a rear baffle valve is provided on the indoor exhaust pipe to control the on-off of the gas in the indoor exhaust pipe.

[0011] Preferably, the rear baffle valve comprises a baffle valve body, the baffle valve body has an air inlet at the bottom and a plurality of air outlets on the side wall; and the baffle valve plate in the baffle valve body rises and falls under the action of the valve plate cylinder; When the valve plate of the flapper valve moves downward to the lower sealing ring, the rear flapper valve is closed; When the valve plate of the baffle valve moves upward to the upper sealing ring, the rear baffle valve is opened.

[0012] Preferably, the front baffle valve is installed on the smoke guide pipe between the main smoke pipe and the fan, and is used to control the on-off of smoke in the smoke guide pipe at that location; An external channel is also provided on the front baffle valve; when the front baffle valve is in an open state, the fan introduces the flue gas in the main smoke duct into the SCR catalytic reduction device, and when the front baffle valve is in a closed state, the fan introduces external air into the SCR catalytic reduction device through the external channel.

[0013] Preferably, the SCR catalytic reduction device comprises a static mixing zone, a flue gas heating zone and an SCR reaction zone which are sequentially arranged along the flue gas flow direction; The static mixing zone is provided with a urea nozzle for spraying urea as a reducing agent to mix with the flue gas; A plurality of heating pipes are arranged in sequence in the flue gas heating zone along the flue gas flow direction, and the flue gas is heated by the heating pipes; A catalyst carrier is arranged in the SCR reaction zone. Under the action of the SCR catalyst, urea is decomposed and chemically reacts with nitrogen oxides, thereby effectively reducing harmful substances in the flue gas.

[0014] Preferably, the SCR catalytic reduction device is connected to the fan via a combined smoke guide pipe, the combined smoke guide pipe comprises a main smoke guide pipe and a bypass smoke guide pipe, the diameter of the main smoke guide pipe is larger than the diameter of the bypass smoke guide pipe, and the two ends of the main smoke guide pipe and the bypass smoke guide pipe are respectively connected to the SCR catalytic reduction device and the fan, and both can introduce the flue gas from the fan into the SCR catalytic reduction device; A first electric butterfly valve is provided at one end of the main smoke pipe close to the fan, for controlling the on and off of smoke in the main smoke pipe; A second electric butterfly valve is provided at one end of the bypass smoke duct close to the fan, for controlling the on-off of smoke in the bypass smoke duct; When the flue gas flow in the main smoke duct is large, the first electric butterfly valve is opened and the second electric butterfly valve is closed, so that the flue gas is introduced into the SCR catalytic reduction device from the main smoke duct; when the flue gas flow in the main smoke duct is small, the first electric butterfly valve is closed and the second electric butterfly valve is opened, so that the flue gas is introduced into the SCR catalytic reduction device from the bypass smoke duct, so as to ensure the flow rate of the flue gas entering the SCR catalytic reduction device.

[0015] Preferably, an orifice flowmeter is installed on the main smoke pipe to monitor the flow of smoke in the main smoke pipe; A gas flow meter is installed on the bypass smoke duct to monitor the flow rate of smoke in the bypass smoke duct; The main smoke pipe is provided with a pressure transmitter for monitoring the gas pressure of the smoke in the main smoke pipe; A nitrogen oxide sensor detection point is provided at one end of the main smoke pipe close to the SCR catalytic reduction device, which is used to detect the nitrogen oxide content of the flue gas before treatment, and the spraying amount of urea is controlled after comparison and calculation with the nitrogen oxide content of the flue gas detected by the nitrogen oxide sensor detection point at the rear end of the SCR catalytic reduction device.

[0016] The present invention also provides a method for using a device for treating nitrogen oxides in flue gas in a heat treatment workshop, comprising the following steps: Step A: First, connect the flue gas collection pipes of multiple heat treatment furnaces to the main flue pipe, and connect two branch pipes from the main flue pipe, one of which is connected to the front baffle valve, and the other is connected to the four-way reversing valve. By controlling the on and off of the front baffle valve and the rear baffle valve and the gear switching of the four-way reversing valve, the following modes can be achieved; Step B: Normal mode, used for flue gas catalytic reduction treatment under normal conditions; Step B1: In this mode, the front baffle valve is in an open state, the rear baffle valve is in a closed state, and the four-way reversing valve is switched to gear B; Step B2: The smoke in the main smoke pipe is introduced into the SCR catalytic reduction device through the front baffle valve and the combined smoke guide pipe under the action of the fan, and then discharged to the outside through the four-way reversing valve; Step B3: When the flue gas enters the SCR catalytic reduction device, it is first mixed with urea sprayed by the urea nozzle in the static mixing zone, then heated by the multiple heating tubes passing through the flue gas heating zone, and then chemically reacts with the SCR catalyst in the catalyst carrier in the SCR reaction zone to reduce the nitrogen oxides in the flue gas into nitrogen and water; Step B4: When the flue gas flow and pressure values ​​monitored by the orifice flowmeter and the pressure transmitter are less than the rated values, the first electric butterfly valve is closed and the second electric butterfly valve is opened. At this time, the flue gas is introduced into the SCR catalytic reduction device through the bypass smoke guide pipe to increase the flow rate of the flue gas entering the SCR catalytic reduction device; Step B5: When the flue gas flow value monitored by the gas flow meter is greater than the rated value, the second electric butterfly valve is closed and the first electric butterfly valve is opened. At this time, the flue gas is introduced into the SCR catalytic reduction device through the main flue gas pipe to reduce the flow rate of the flue gas entering the SCR catalytic reduction device, thereby improving the effect of the catalytic reduction reaction; Step C: Debugging mode, equipment debugging is performed without stopping the heat treatment furnace; Step C1: In this mode, the front baffle valve is in a closed state, the rear baffle valve is in an open state, and the four-way reversing valve is switched to gear A; Step C2: After indoor air is introduced into the SCR catalytic reduction device under the action of the fan, it is discharged into the room through the four-way reversing valve and the tailgate valve, and the flue gas in the main smoke pipe is discharged outdoors through the four-way reversing valve; Step D: Override mode, in which the concentration of nitrogen oxides in the room is increased without stopping the heat treatment furnace, so as to detect the catalytic reduction effect of the SCR catalytic reduction device during debugging; Step D1: In this mode, the front baffle valve is in a closed state, the rear baffle valve is in an open state, and the four-way reversing valve is switched to gear B; Step D2: After the indoor air is introduced into the SCR catalytic reduction device under the action of the fan, it is discharged to the outside through the four-way reversing valve, and the flue gas in the main smoke pipe is discharged to the room through the four-way reversing valve and the rear baffle valve; Step E: Pipe emptying mode, quickly empty the flue gas in the pipeline and perform maintenance on the equipment; Step E1: In this mode, the front baffle valve is in an open state, the rear baffle valve is in an open state, and the four-way reversing valve is switched to gear A; Step E2: Under the action of the fan, the flue gas in the main smoke duct is introduced into the SCR catalytic reduction device through the front baffle valve and the combined smoke guide pipe, and then discharged into the room through the four-way reversing valve and the rear baffle valve; at the same time, the flue gas in the main smoke duct is discharged outdoors through the four-way reversing valve.

[0017] Compared with the prior art, the present invention has the following beneficial effects: 1. The present invention adds a front baffle valve, a rear baffle valve and a four-way reversing valve to the nitrogen oxide treatment equipment in the flue gas of the heat treatment workshop. Through the opening and closing of the front baffle valve and the rear baffle valve and the gear switching of the four-way reversing valve, multiple operation modes of the oxide treatment equipment can be realized; 2. The present invention also adds a combined smoke guide pipe to the nitrogen oxide treatment equipment in the flue gas of the heat treatment workshop. When the flue gas flow in the main smoke pipe is large, the flue gas enters the SCR catalytic reduction device through the main smoke guide pipe with a larger diameter, and when the flue gas flow in the main smoke pipe is small, the flue gas enters the SCR catalytic reduction device through the bypass smoke guide pipe with a smaller diameter, thereby always ensuring the flow rate of the flue gas entering the SCR catalytic reduction device; 3. The nitrogen oxide treatment equipment in the flue gas of the heat treatment workshop of the present invention can realize the switching of four modes: normal, debugging, exceeding and pipe emptying, so as to meet the requirements of flue gas catalytic reduction treatment, equipment debugging without stopping the heat treatment furnace, increasing the concentration of nitrogen oxides in the room, detecting the catalytic reduction effect of the SCR catalytic reduction device during debugging, and switching in four scenarios such as quickly emptying the flue gas in the pipeline and repairing and maintaining the equipment. BRIEF DESCRIPTION OF THE DRAWINGS

[0018] Figure 1It is a structural schematic diagram of the nitrogen oxide treatment equipment in the flue gas of a heat treatment workshop provided by the present invention; Figure 2 It is a top view of the nitrogen oxide treatment equipment in the flue gas of a heat treatment workshop provided by the present invention; Figure 3 This is a front view of the equipment for treating nitrogen oxides in flue gas of a heat treatment workshop provided by the present invention; Figure 4 It is a side view of the equipment for treating nitrogen oxides in flue gas of a heat treatment workshop provided by the present invention; Figure 5 It is a structural schematic diagram of the four-way reversing valve provided by the present invention; Figure 6 is a front view of the four-way reversing valve provided by the present invention; Figure 7 is a side view of the four-way reversing valve provided by the present invention; Figure 8 It is an internal structure diagram of the four-way reversing valve provided by the present invention; Fig. 9 It is a structural schematic diagram of the rear baffle valve provided by the present invention; Fig.10 is a cross-sectional view of a rear baffle valve provided by the present invention; Fig.11 It is a structural schematic diagram of the front baffle valve provided by the present invention; Fig.12 It is a structural schematic diagram of the SCR catalytic reduction device provided by the present invention; Fig.13 is a top view of the SCR catalytic reduction device provided by the present invention; Fig.14 It is a schematic diagram of the internal structure of the SCR catalytic reduction device provided by the present invention; Fig.15 It is a structural schematic diagram of the combined smoke guide pipe provided by the present invention; Fig.16 is a flow diagram of smoke in a normal mode provided by the present invention; Fig.17 It is a flow diagram of smoke in the debugging mode provided by the present invention; Fig.18 is a flow diagram of flue gas in the overtaking mode provided by the present invention; Fig.19 It is a flow diagram of smoke in the tube emptying mode provided by the present invention.

[0019] In the figure: 1. Main smoke pipe; 2. SCR catalytic reduction device; 3. Fan; 4. Front baffle valve; 5. Four-way reversing valve; 6. Rear smoke pipe; 7. Outdoor discharge pipe; 8. Indoor discharge pipe; 9. Rear baffle valve; 10. Main smoke pipe; 11. Bypass smoke pipe; 12. First electric butterfly valve; 13. Second electric butterfly valve; 14. Orifice flowmeter; 15. Gas flowmeter; 16. Pressure transmitter; 17. Nitrogen oxide sensor detection point; 201, static mixing zone; 202, flue gas heating zone; 203, SCR reaction zone; 2011, urea nozzle; 2021, heating tube; 2031, catalyst carrier; 401, external passage; 501, cylindrical valve body; 502, smoke pipe interface; 503, reversing valve plate; 504, driving shaft; 505, driving cylinder; 901, baffle valve body; 902, air inlet; 903, air outlet; 904, baffle valve plate; 905, valve plate cylinder. DETAILED DESCRIPTION

[0020] The present invention is further described in detail below in conjunction with the accompanying drawings and specific embodiments. The advantages and features of the present invention will become more apparent from the following description and claims. It should be noted that the drawings are in very simplified form and in non-precise proportions, and are only used to conveniently and clearly assist in explaining the purpose of the embodiments of the present invention.

[0021] In the description of the present invention, it should be understood that the terms "center", "longitudinal", "lateral", "up", "down", "front", "back", "left", "right", "vertical", "horizontal", "top", "bottom", "inside", "outside" and the like indicate positions or positional relationships based on the positions or positional relationships shown in the accompanying drawings, and are only for the convenience of describing the present invention and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore cannot be understood as limiting the present invention. In addition, the terms "first", "second", and the like are only used for descriptive purposes, and cannot be understood as indicating or implying relative importance or implicitly indicating the number of technical features indicated. Thus, features defined as "first", "second", and the like may explicitly or implicitly include one or more of the features. In the description of the present invention, unless otherwise specified, "multiple" means two or more.

[0022] In the description of the present invention, it should be noted that, unless otherwise clearly specified and limited, the terms "installed", "connected", and "connected" should be understood in a broad sense, for example, it can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection or an electrical connection; it can be a direct connection, or it can be indirectly connected through an intermediate medium, or it can be the internal communication of two components. For ordinary technicians in this field, the specific meanings of the above terms in the present invention can be understood by specific circumstances.

[0023] In addition, the features, operations, and characteristics described in the specification can be combined in any appropriate manner to form various embodiments. Similarly, the steps or actions described in the method can also be adjusted in order in a manner that can be easily seen by those skilled in the art. Therefore, the various sequences in the specification and drawings are only for the purpose of describing a certain embodiment, and are not necessarily such sequences, unless otherwise stated that a certain sequence must be followed.

[0024] Embodiment 1 The present invention provides a device for treating nitrogen oxides in flue gas from a heat treatment workshop. Figure 1-4 , including: a main smoke pipe 1, in which the flue gas generated by multiple heat treatment furnaces in the heat treatment workshop is collected and flows; an SCR catalytic reduction device 2, in which the SCR catalytic reduction device 2 is connected to the main smoke pipe 1 through a smoke guide pipe; a fan 3, which is arranged between the SCR catalytic reduction device 2 and the main smoke pipe 1, so as to introduce the flue gas in the main smoke pipe 1 into the SCR catalytic reduction device 2; a front baffle valve 4, which is installed on the smoke guide pipe between the SCR catalytic reduction device 2 and the main smoke pipe 1, and is used to control the on and off of the flue gas in the smoke guide pipe; a four-way reversing valve 5, which has four smoke pipe interfaces, the first smoke pipe interface is connected to the main smoke pipe 1, the second smoke pipe interface is connected to the rear end smoke guide pipe 6 of the SCR catalytic reduction device 2, the third smoke pipe interface is connected to the outdoor exhaust pipe 7, and the fourth smoke pipe interface is connected to the indoor exhaust pipe 8; the four-way reversing valve 5 has at least two gears, and by switching different gears, multiple operation modes of the nitrogen oxide treatment equipment can be realized.

[0025] For details, please refer to Figure 5-7 The four-way reversing valve 5 includes a cylindrical valve body 501, and four smoke pipe interfaces 502 connected to the inner cavity of the cylindrical valve body 501 are arranged on the side wall of the cylindrical valve body 501, and a reversing valve plate 503 is arranged inside the cylindrical valve body 501, and the middle of the reversing valve plate 503 is rotatably connected to the cylindrical valve body 501 through a driving shaft 504.

[0026] Furthermore, the four-way reversing valve 5 is also configured with a driving cylinder 505, and the telescopic rod of the driving cylinder 505 is connected to the driving shaft 504 through a crank connecting rod. As the piston rod of the driving cylinder 505 is extended and retracted, the crank connecting rod drives the driving shaft 504 and the reversing valve plate 503 connected to the driving shaft 504 to rotate, thereby switching the different gears of the four-way reversing valve 5.

[0027] Further, such as Figure 8 As shown, the four-way reversing valve 5 has two gears, namely, gear A and gear B; one of the smoke pipe interfaces 502 of the four-way reversing valve 5 is always connected to the rear end smoke guide pipe 6 of the SCR catalytic reduction device 2, and the reversing valve plate 503 rotates 90 degrees under the action of the driving cylinder 505, switching between gear A and gear B, thereby connecting two of the other three smoke pipe interfaces 502.

[0028] For details, please refer to Fig. 9 and Fig.10 The indoor exhaust pipe 8 is provided with a rear baffle valve 9 for controlling the on-off of the gas in the indoor exhaust pipe 8 .

[0029] Furthermore, the rear baffle valve 9 includes a baffle valve body 901 , the baffle valve body 901 has an air inlet 902 at the bottom, and a plurality of air outlets 903 on the side wall; and the baffle valve plate 904 in the baffle valve body 901 rises and falls under the action of the valve plate cylinder 905 .

[0030] When the flapper valve plate 904 moves downward to the lower sealing ring, the rear flapper valve 9 is closed; when the flapper valve plate 904 moves upward to the upper sealing ring, the rear flapper valve 9 is opened.

[0031] For details, please refer to Fig.11 The front baffle valve 4 is installed on the smoke guide pipe between the main smoke pipe 1 and the fan 3, and is used to control the on-off of the smoke in the smoke guide pipe; the front baffle valve 4 is also provided with an external channel 401; when the front baffle valve 4 is in an open state, the fan 3 introduces the smoke in the main smoke pipe 1 into the SCR catalytic reduction device 2, and when the front baffle valve 4 is in a closed state, the fan 3 introduces external air into the SCR catalytic reduction device 2 through the external channel 401.

[0032] For details, please refer to Figure 12-14 The SCR catalytic reduction device 2 includes a static mixing zone 201, a flue gas heating zone 202 and an SCR reaction zone 203 which are sequentially arranged along the flue gas flow direction.

[0033] The static mixing zone 201 is provided with a urea nozzle 2011 for spraying urea as a reducing agent to mix with the flue gas.

[0034] In some embodiments, the urea spray heads 2011 are provided with two groups, one group sprays urea normally and the other group is in standby.

[0035] A plurality of heating tubes 2021 are sequentially arranged in the flue gas heating zone 202 along the flue gas flow direction, and the flue gas is heated by the heating tubes 2021 .

[0036] A catalyst carrier 2031 is provided in the SCR reaction zone 203. Under the action of the SCR catalyst, urea is decomposed and chemically reacts with nitrogen oxides, thereby effectively reducing harmful substances in the flue gas.

[0037] For details, please refer to Fig.15 The SCR catalytic reduction device 2 is connected to the fan 3 through a combined smoke guide pipe, which includes a main smoke guide pipe 10 and a bypass smoke guide pipe 11. The diameter of the main smoke guide pipe 10 is larger than the diameter of the bypass smoke guide pipe 11, and the two ends of the main smoke guide pipe 10 and the bypass smoke guide pipe 11 are respectively connected to the SCR catalytic reduction device 2 and the fan 3, and both can introduce the flue gas from the fan 3 into the SCR catalytic reduction device 2.

[0038] A first electric butterfly valve 12 is provided at one end of the main smoke duct 10 close to the fan 3 for controlling the on-off of smoke in the main smoke duct 10 ; a second electric butterfly valve 13 is provided at one end of the bypass smoke duct 11 close to the fan 3 for controlling the on-off of smoke in the bypass smoke duct 11 .

[0039] When the flue gas flow in the main smoke duct 1 is large, the first electric butterfly valve 12 is opened and the second electric butterfly valve 13 is closed, so that the flue gas is introduced into the SCR catalytic reduction device 2 from the main smoke duct 10; when the flue gas flow in the main smoke duct 1 is small, the first electric butterfly valve 12 is closed and the second electric butterfly valve 13 is opened, so that the flue gas is introduced into the SCR catalytic reduction device 2 from the bypass smoke duct 11, so as to ensure the flow rate of the flue gas entering the SCR catalytic reduction device 2.

[0040] Furthermore, an orifice flowmeter 14 is installed on the main smoke pipe 10 to monitor the flow rate of smoke in the main smoke pipe 10; a gas flowmeter 15 is installed on the bypass smoke pipe 11 to monitor the flow rate of smoke in the bypass smoke pipe 11; and a pressure transmitter 16 is installed on the main smoke pipe 10 to monitor the gas pressure of the smoke in the main smoke pipe 10.

[0041] A nitrogen oxide sensor detection point 17 is provided at one end of the main smoke pipe 10 close to the SCR catalytic reduction device 2 for detecting the nitrogen oxide content of the flue gas before treatment, and controlling the spraying amount of urea after comparing and calculating with the nitrogen oxide content of the flue gas detected by the nitrogen oxide sensor detection point at the rear end of the SCR catalytic reduction device 2.

[0042] Embodiment 2 The present invention also provides a method for using a device for treating nitrogen oxides in flue gas in a heat treatment workshop, comprising the following steps: Step A: First, the smoke collection pipes of multiple heat treatment furnaces are connected to the main smoke pipe 1, and two branch pipes are connected to the main smoke pipe 1, one of which is connected to the front baffle valve 4, and the other is connected to the four-way reversing valve 5. By controlling the on and off of the front baffle valve 4 and the rear baffle valve 9 and the gear switching of the four-way reversing valve 5, the following modes are realized; Step B: Normal mode, used for flue gas catalytic reduction treatment under normal conditions; Step B1: Fig.16 As shown, in this mode, the front damper valve 4 is in an open state, the rear damper valve 9 is in a closed state, and the four-way reversing valve 5 is switched to the B gear; Step B2: The smoke in the main smoke pipe 1 is introduced into the SCR catalytic reduction device 2 through the front baffle valve 4 and the combined smoke guide pipe under the action of the fan 3, and then discharged to the outside through the four-way reversing valve 5; Step B3: When the flue gas enters the SCR catalytic reduction device 2, it is first mixed with urea sprayed by the urea nozzle 2011 in the static mixing zone 201, then heated by the multi-channel heating tubes 2021 passing through the flue gas heating zone 202, and then chemically reacts with the SCR catalyst in the catalyst carrier 2031 in the SCR reaction zone 203 to reduce the nitrogen oxides in the flue gas into nitrogen and water; Step B4: When the flue gas flow and pressure values ​​monitored by the orifice flowmeter 14 and the pressure transmitter 16 are less than the rated values, the first electric butterfly valve 12 is closed and the second electric butterfly valve 13 is opened. At this time, the flue gas is introduced into the SCR catalytic reduction device 2 through the bypass smoke guide pipe 11 to increase the flow rate of the flue gas entering the SCR catalytic reduction device 2, thereby saving the amount of urea and reducing the use cost of the overall equipment; Step B5: When the flue gas flow value monitored by the gas flow meter 15 is greater than the rated value, the second electric butterfly valve 13 is closed and the first electric butterfly valve 12 is opened. At this time, the flue gas is introduced into the SCR catalytic reduction device 2 through the main flue gas pipe 10 to reduce the flow rate of the flue gas entering the SCR catalytic reduction device 2, thereby improving the effect of the catalytic reduction reaction; Step C: Debugging mode, equipment debugging is performed without stopping the heat treatment furnace; Step C1: Fig.17As shown, in this mode, the front baffle valve 4 is in a closed state, the rear baffle valve 9 is in an open state, and the four-way reversing valve 5 is switched to gear A; Step C2: After indoor air is introduced into the SCR catalytic reduction device 2 under the action of the fan 3, it is discharged into the room through the four-way reversing valve 5 and the tailgate valve 9, and the flue gas in the main smoke pipe 1 is discharged outdoors through the four-way reversing valve 5; Step D: Override mode, in which the concentration of nitrogen oxides in the room is increased without stopping the heat treatment furnace, so as to detect the catalytic reduction effect of the SCR catalytic reduction device 2 during debugging; Step D1: Fig.18 As shown, in this mode, the front damper valve 4 is in a closed state, the rear damper valve 9 is in an open state, and the four-way reversing valve 5 is switched to the B gear; Step D2: After the indoor air is introduced into the SCR catalytic reduction device 2 by the action of the fan 3, it is discharged to the outside through the four-way reversing valve 5, and the flue gas in the main smoke pipe 1 is discharged to the indoor through the four-way reversing valve 5 and the rear baffle valve 9; Step E: Pipe emptying mode, quickly empty the flue gas in the pipeline and perform maintenance on the equipment; Step E1: Fig.19 As shown, in this mode, the front baffle valve 4 is in an open state, the rear baffle valve 9 is in an open state, and the four-way reversing valve 5 is switched to gear A; Step E2: Under the action of the fan 3, the flue gas in the main smoke pipe 1 is introduced into the SCR catalytic reduction device 2 through the front baffle valve 4 and the combined smoke guide pipe, and then discharged into the room through the four-way reversing valve 5 and the rear baffle valve 9; at the same time, the flue gas in the main smoke pipe 1 is discharged outdoors through the four-way reversing valve 5.

[0043] The nitrogen oxide treatment equipment in the flue gas of a heat treatment workshop adopting the present invention can realize the switching of four modes: normal, debugging, exceeding and pipe emptying, so as to meet the requirements of flue gas catalytic reduction treatment, equipment debugging without stopping the heat treatment furnace, increasing the concentration of indoor nitrogen oxides, detecting the catalytic reduction effect of the SCR catalytic reduction device during debugging, and switching in four scenarios such as quickly emptying the flue gas in the pipeline and repairing and maintaining the equipment.

[0044] The above description is only a description of the preferred embodiments of the present invention, and is not intended to limit the scope of the present invention. Any changes or modifications made by a person skilled in the art in the field of the present invention based on the above disclosure shall fall within the scope of protection of the claims.

Claims

1. A device for treating nitrogen oxides in flue gas from a heat treatment workshop. It is characterized in that include: A main smoke pipe (1), in which smoke generated by a plurality of heat treatment furnaces in a heat treatment workshop is collected and flows; An SCR catalytic reduction device (2), wherein the SCR catalytic reduction device (2) is connected to the main smoke pipe (1) via a smoke guide pipe; a fan (3) disposed between the SCR catalytic reduction device (2) and the main smoke pipe (1), so as to introduce the smoke in the main smoke pipe (1) into the SCR catalytic reduction device (2); A front baffle valve (4) is installed on the smoke guide pipe between the SCR catalytic reduction device (2) and the main smoke pipe (1) and is used to control the on and off of smoke in the smoke guide pipe; A four-way reversing valve (5), the four-way reversing valve (5) having four smoke pipe interfaces, a first smoke pipe interface being connected to the main smoke pipe (1), a second smoke pipe interface being connected to a rear end smoke guide pipe (6) of the SCR catalytic reduction device (2), a third smoke pipe interface being connected to an outdoor exhaust pipe (7), and a fourth smoke pipe interface being connected to an indoor exhaust pipe (8); The four-way reversing valve (5) has at least two gear positions, and various operating modes of the nitrogen oxide treatment equipment can be realized by switching different gear positions.

2. A device for treating nitrogen oxides in flue gas from a heat treatment workshop as claimed in claim 1, It is characterized in that The four-way reversing valve (5) comprises a cylindrical valve body (501), four smoke pipe interfaces (502) communicating with the inner cavity of the cylindrical valve body (501) are arranged on the side wall of the cylindrical valve body (501), and a reversing valve plate (503) is arranged inside the cylindrical valve body (501), and the middle of the reversing valve plate (503) is rotatably connected to the cylindrical valve body (501) via a driving shaft (504); The four-way reversing valve (5) is further provided with a driving cylinder (505), the telescopic rod of the driving cylinder (505) being connected to the driving shaft (504) via a crank connecting rod; as the piston rod of the driving cylinder (505) is extended or retracted, the crank connecting rod drives the driving shaft (504) and the reversing valve plate (503) connected to the driving shaft (504) to rotate, thereby switching different gears of the four-way reversing valve (5).

3. A device for treating nitrogen oxides in flue gas from a heat treatment workshop as claimed in claim 2, It is characterized in that The four-way reversing valve (5) has two gear positions, namely gear A and gear B; One of the smoke pipe interfaces (502) of the four-way reversing valve (5) is always connected to the rear end smoke guide pipe (6) of the SCR catalytic reduction device (2), and the reversing valve plate (503) rotates 90 degrees under the action of the driving cylinder (505) to switch between gear A and gear B, thereby connecting two of the other three smoke pipe interfaces (502).

4. A device for treating nitrogen oxides in flue gas from a heat treatment workshop as claimed in claim 3, It is characterized in that The indoor discharge pipe (8) is provided with a rear baffle valve (9) for controlling the on-off of gas in the indoor discharge pipe (8).

5. The device for treating nitrogen oxides in flue gas of a heat treatment workshop as claimed in claim 4, It is characterized in that The rear baffle valve (9) comprises a baffle valve body (901), the baffle valve body (901) has an air inlet (902) at the bottom, and a plurality of air outlets (903) are provided on the side wall; and a baffle valve plate (904) in the baffle valve body (901) rises and falls under the action of a valve plate cylinder (905); When the flapper valve plate (904) moves downward to the lower sealing ring, the rear flapper valve (9) is closed; When the baffle valve plate (904) moves upward to the upper sealing ring, the rear baffle valve (9) is opened.

6. The device for treating nitrogen oxides in flue gas of a heat treatment workshop according to claim 1, It is characterized in that The front baffle valve (4) is installed on the smoke guide pipe between the main smoke pipe (1) and the fan (3) and is used to control the on and off of smoke in the smoke guide pipe at that location; The front baffle valve (4) is also provided with an external passage (401); when the front baffle valve (4) is in an open state, the fan (3) introduces the flue gas in the main flue pipe (1) into the SCR catalytic reduction device (2); and when the front baffle valve (4) is in a closed state, the fan (3) introduces external air into the SCR catalytic reduction device (2) through the external passage (401).

7. The device for treating nitrogen oxides in flue gas of a heat treatment workshop according to claim 1, It is characterized in that The SCR catalytic reduction device (2) comprises a static mixing zone (201), a flue gas heating zone (202) and an SCR reaction zone (203) which are arranged in sequence along the flue gas flow direction; The static mixing zone (201) is provided with a urea spray nozzle (211) for spraying urea as a reducing agent to mix with the flue gas; A plurality of heating pipes (221) are sequentially arranged in the flue gas heating zone (202) along the flue gas flow direction, and the flue gas is heated by the heating pipes (221); A catalyst carrier (2031) is provided in the SCR reaction zone (203). Under the action of the SCR catalyst, urea is decomposed and chemically reacts with nitrogen oxides, thereby effectively reducing harmful substances in the flue gas.

8. The device for treating nitrogen oxides in flue gas of a heat treatment workshop according to claim 1, It is characterized in that The SCR catalytic reduction device (2) and the fan (3) are connected via a combined smoke guide pipe, the combined smoke guide pipe comprising a main smoke guide pipe (10) and a bypass smoke guide pipe (11), the diameter of the main smoke guide pipe (10) being larger than the diameter of the bypass smoke guide pipe (11), and the two ends of the main smoke guide pipe (10) and the bypass smoke guide pipe (11) are respectively connected to the SCR catalytic reduction device (2) and the fan (3), and both can introduce smoke from the fan (3) into the SCR catalytic reduction device (2); A first electric butterfly valve (12) is provided at one end of the main smoke pipe (10) close to the fan (3) for controlling the on and off of smoke in the main smoke pipe (10); A second electric butterfly valve (13) is provided at one end of the bypass smoke guide pipe (11) close to the fan (3) for controlling the on and off of smoke in the bypass smoke guide pipe (11); When the flue gas flow rate in the main flue gas duct (1) is relatively large, the first electric butterfly valve (12) is opened and the second electric butterfly valve (13) is closed, so that the flue gas is introduced from the main flue gas duct (10) into the SCR catalytic reduction device (2); when the flue gas flow rate in the main flue gas duct (1) is relatively small, the first electric butterfly valve (12) is closed and the second electric butterfly valve (13) is opened, so that the flue gas is introduced from the bypass flue gas duct (11) into the SCR catalytic reduction device (2), so as to ensure the flow rate of the flue gas entering the SCR catalytic reduction device (2).

9. The device for treating nitrogen oxides in flue gas of a heat treatment workshop as claimed in claim 8, It is characterized in that An orifice flow meter (14) is installed on the main smoke pipe (10) for monitoring the flow rate of smoke in the main smoke pipe (10); A gas flow meter (15) is installed on the bypass smoke duct (11) for monitoring the flow rate of smoke in the bypass smoke duct (11); The main smoke pipe (10) is provided with a pressure transmitter (16) for monitoring the gas pressure of smoke in the main smoke pipe (10); A nitrogen oxide sensor detection point (17) is provided at one end of the main smoke pipe (10) close to the SCR catalytic reduction device (2) for detecting the nitrogen oxide content of the smoke before treatment, and controlling the spraying amount of urea after comparing and calculating with the nitrogen oxide content of the smoke detected by the nitrogen oxide sensor detection point at the rear end of the SCR catalytic reduction device (2).

10. A method for using the equipment for treating nitrogen oxides in flue gas of a heat treatment workshop as claimed in any one of claims 1 to 9, It is characterized in that The steps include: Step A: First, the smoke collection pipes of the plurality of heat treatment furnaces are connected to a main smoke pipe (1), and two branch pipes are connected to the main smoke pipe (1), one of the branch pipes is connected to a front baffle valve (4), and the other branch pipe is connected to a four-way reversing valve (5), and the following modes are realized by controlling the on and off of the front baffle valve (4) and the rear baffle valve (9) and the gear switching of the four-way reversing valve (5); Step B: Normal mode, used for flue gas catalytic reduction treatment under normal conditions; Step B1: In this mode, the front baffle valve (4) is in an open state, the rear baffle valve (9) is in a closed state, and the four-way reversing valve (5) is switched to gear B; Step B2: under the action of the fan (3), the smoke in the main smoke pipe (1) is introduced into the SCR catalytic reduction device (2) through the front baffle valve (4) and the combined smoke guide pipe, and then discharged outdoors through the four-way reversing valve (5); Step B3: When the flue gas enters the SCR catalytic reduction device (2), it is first mixed with urea sprayed by the urea nozzle (211) in the static mixing zone (201), then heated by the multi-channel heating tube (221) passing through the flue gas heating zone (202), and then chemically reacts with the SCR catalyst in the catalyst carrier (2031) in the SCR reaction zone (203) to reduce the nitrogen oxides in the flue gas into nitrogen and water; Step B4: when the flue gas flow rate and pressure values ​​monitored by the orifice flow meter (14) and the pressure transmitter (16) are less than the rated values, the first electric butterfly valve (12) is closed and the second electric butterfly valve (13) is opened, and the flue gas is introduced into the SCR catalytic reduction device (2) through the bypass smoke guide pipe (11) to increase the flow rate of the flue gas entering the SCR catalytic reduction device (2); Step B5: when the flue gas flow value monitored by the gas flow meter (15) is greater than the rated value, the second electric butterfly valve (13) is closed and the first electric butterfly valve (12) is opened. At this time, the flue gas is introduced into the SCR catalytic reduction device (2) through the main flue gas pipe (10) to reduce the flow rate of the flue gas entering the SCR catalytic reduction device (2), thereby improving the effect of the catalytic reduction reaction; Step C: Debugging mode, equipment debugging is performed without stopping the heat treatment furnace; Step C1: In this mode, the front baffle valve (4) is in a closed state, the rear baffle valve (9) is in an open state, and the four-way reversing valve (5) is switched to gear A; Step C2: After indoor air is introduced into the SCR catalytic reduction device (2) under the action of the fan (3), it is discharged into the room through the four-way reversing valve (5) and the rear baffle valve (9), while the flue gas in the main smoke pipe (1) is discharged outdoors through the four-way reversing valve (5); Step D: Override mode, in which the concentration of nitrogen oxides in the room is increased without stopping the heat treatment furnace, so as to detect the catalytic reduction effect of the SCR catalytic reduction device (2) during commissioning; Step D1: In this mode, the front baffle valve (4) is in a closed state, the rear baffle valve (9) is in an open state, and the four-way reversing valve (5) is switched to gear B; Step D2: After indoor air is introduced into the SCR catalytic reduction device (2) under the action of the fan (3), it is discharged to the outside through the four-way reversing valve (5), while the flue gas in the main smoke pipe (1) is discharged to the room through the four-way reversing valve (5) and the rear baffle valve (9); Step E: Pipe emptying mode, quickly empty the flue gas in the pipeline and perform maintenance on the equipment; Step E1: In this mode, the front baffle valve (4) is in an open state, the rear baffle valve (9) is in an open state, and the four-way reversing valve (5) is switched to gear A; Step E2: Under the action of the fan (3), the smoke in the main smoke pipe (1) is introduced into the SCR catalytic reduction device (2) through the front baffle valve (4) and the combined smoke guide pipe, and then discharged into the room through the four-way reversing valve (5) and the rear baffle valve (9); at the same time, the smoke in the main smoke pipe (1) is discharged outdoors through the four-way reversing valve (5).

Images