Equipment for treating nitric oxide in flue gas of heat treatment workshop

Abstract

The utility model discloses equipment for treating nitric oxide in flue gas of a heat treatment workshop. The equipment comprises a main smoke pipe, and a front baffle valve, a fan, an SCR (Selective Catalytic Reduction) catalytic reduction device, a four-way reversing valve and a rear baffle valve which are sequentially connected with the main smoke pipe through smoke guide pipes, the fan is used for introducing flue gas in the main flue gas pipe into the SCR catalytic reduction device through the front baffle valve; the four-way reversing valve is provided with four smoke pipe connectors, the first smoke pipe connector is communicated with a main smoke pipe, the second smoke pipe connector is communicated with a smoke guide pipe at the rear end of the SCR catalytic reduction device, the third smoke pipe connector is communicated with an outdoor discharge pipe, and the fourth smoke pipe connector is communicated with an indoor discharge pipe. By adopting the treatment equipment disclosed by the utility model, the switching among four modes, namely a normal mode, a debugging mode, an overrunning mode and a pipe emptying mode can be realized, so that the switching use in four scenes, such as flue gas catalytic reduction treatment, equipment debugging under the condition that a heat treatment furnace is not stopped, indoor nitrogen oxide concentration improvement and equipment maintenance can be met.

Description

TECHNICAL FIELD

[0001] The utility model relates to the technical field of flue gas denitration equipment, especially to a kind of nitrogen oxides processing equipment in heat treatment workshop flue gas. BACKGROUND

[0002] Heat treatment workshop plays an important role in metal processing process, and the mechanical properties and physical properties of materials are improved by processes such as annealing, quenching and tempering. However, these high-temperature treatment processes usually emit flue gas containing nitrogen oxides (NOx), which causes serious pollution to the environment. Nitrogen oxides are a major atmospheric pollutant that can form smog, acid rain and photochemical smog, causing harm to human health and ecosystems.

[0003] Currently, the commonly used technology for treating nitrogen oxides in heat treatment workshop flue gas 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 catalyst, when the exhaust temperature is between 300℃ and 450℃, urea, a reducing agent, is injected into the flue gas to reduce NOx in the flue gas to N2 and H2O. The catalyst is coated with vanadium-based or molecular sieve on the surface of honeycomb ceramic, with a structure of 200-300 mesh, and the space velocity can reach 15000 h-1, with a conversion rate of more than 90%.

[0004] The existing flue gas treatment equipment usually directly collects flue gas into the SCR catalytic reduction device and discharges it to the outdoor after treatment. This type of flue gas treatment equipment needs to be installed, adjusted or cleaned and maintained in the heat treatment furnace in the workshop under the condition of shutdown. In actual situation, a large amount of energy is consumed for each heating of the heat treatment furnace, so it usually works continuously for 24 hours, and the flue gas treatment equipment needs to be cleaned and maintained regularly and adjusted and stabilized before it can effectively treat nitrogen oxides in flue gas to meet the emission standards.

[0005] Therefore, the development of an economical and efficient, stable and reliable nitrogen oxides treatment equipment can truly solve the problem of flue gas treatment in heat treatment workshop. UTILITY MODEL CONTENTS

[0006] The utility model aims at providing a kind of nitrogen oxides treatment equipment in heat treatment workshop flue gas, to solve the problem that the existing flue gas treatment equipment cannot complete equipment cleaning and maintenance and adjustment under the condition of continuous work of heat treatment furnace.

[0007] To solve the above technical problems, the utility model provides a kind of nitrogen oxides treatment equipment in heat treatment workshop flue gas, including total smoke pipe and front baffle valve, fan, SCR catalytic reduction device, four-way reversing valve and rear baffle valve connected with total smoke pipe in turn by smoke guide pipe;

[0008] The fan introduces the flue gas in the total flue pipe into the SCR catalytic reduction device through the front baffle valve;

[0009] The four-way reversing valve has four flue pipe interfaces, the first flue pipe interface is communicated with the total flue pipe, the second flue pipe interface is communicated with the rear-end flue pipe of the SCR catalytic reduction device, the third flue pipe interface is communicated with the outdoor exhaust pipe, and the fourth flue pipe interface is communicated with the indoor exhaust pipe;

[0010] The rear baffle valve is installed on the indoor exhaust pipe and is used for controlling the on-off of the flue gas in the indoor exhaust pipe;

[0011] The four-way reversing valve has at least two gears, and different gears are switched to realize multiple operation modes of the nitrogen oxide treatment equipment.

[0012] Preferably, the four-way reversing valve comprises a cylindrical valve body, four flue pipe interfaces are arranged on the side wall of the cylindrical valve body and communicated with the inner cavity of the cylindrical valve body, and a reversing valve plate is arranged in the cylindrical valve body, and the reversing valve plate is rotationally connected with the cylindrical valve body through a driving shaft.

[0013] Preferably, the four-way reversing valve is further provided with a driving cylinder, a connecting rod is connected between the telescopic rod of the driving cylinder and the driving shaft, and the connecting rod drives the driving shaft and the reversing valve plate connected with the driving shaft to rotate, so as to switch different gears of the four-way reversing valve, along with the extension and retraction of the piston rod of the driving cylinder.

[0014] Preferably, the four-way reversing valve has two gears, namely gear A and gear B.

[0015] One of the flue pipe interfaces of the four-way reversing valve is always communicated with the rear-end flue pipe of the SCR catalytic reduction device, and the reversing valve plate rotates 90 degrees under the action of the driving cylinder to switch between gear A and gear B, so as to communicate two of the other three flue pipe interfaces.

[0016] Preferably, the rear baffle valve comprises a baffle valve body, an air inlet is arranged at the bottom of the baffle valve body, and a plurality of air outlets are arranged on the side wall of the baffle valve body; and a baffle valve plate in the baffle valve body is lifted and lowered under the action of a valve plate cylinder.

[0017] When the baffle valve plate is lowered to the lower sealing ring, the rear baffle valve is closed;

[0018] When the baffle valve plate is raised to the upper sealing ring, the rear baffle valve is opened.

[0019] Preferably, the front baffle valve is installed on the flue pipe between the total flue pipe and the fan, and is used for controlling the on-off of the flue gas in the flue pipe.

[0020] The front baffle valve is further provided with an outer passage; when the front baffle valve is in an open state, the fan introduces flue gas in the total flue pipe into the SCR catalytic reduction device; when the front baffle valve is in a closed state, the fan introduces external air into the SCR catalytic reduction device through the outer passage.

[0021] Preferably, the SCR catalytic reduction device comprises a static mixing zone, a flue gas heating zone and an SCR reaction zone arranged in sequence along the flue gas flow direction;

[0022] The static mixing zone is provided with a urea spray head for spraying urea as a reducing agent to mix with flue gas;

[0023] The flue gas heating zone is provided with a plurality of heating pipes arranged in sequence along the flue gas flow direction, and the flue gas is heated by the heating pipes;

[0024] The SCR reaction zone is provided with a catalyst carrier, and under the action of the SCR catalyst, urea is decomposed and chemically reacts with nitrogen oxides to effectively reduce harmful substances in the flue gas.

[0025] Preferably, the SCR catalytic reduction device and the fan are connected through a combined smoke guide pipe, the combined smoke guide pipe comprises a main smoke guide pipe and a bypass smoke guide pipe, the pipe diameter of the main smoke guide pipe is greater than the pipe 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 flue gas from the fan into the SCR catalytic reduction device.

[0026] Preferably, the end of the main smoke guide pipe close to the fan is provided with a first electric butterfly valve for controlling the on-off of flue gas in the main smoke guide pipe; the end of the bypass smoke guide pipe close to the fan is provided with a second electric butterfly valve for controlling the on-off of flue gas in the bypass smoke guide pipe;

[0027] When the flue gas flow in the total flue pipe is large, the first electric butterfly valve is opened and the second electric butterfly valve is closed, so that flue gas is introduced from the main smoke guide pipe into the SCR catalytic reduction device; when the flue gas flow in the total flue pipe is small, the first electric butterfly valve is closed and the second electric butterfly valve is opened, so that flue gas is introduced from the bypass smoke guide pipe into the SCR catalytic reduction device, to ensure the flow rate of flue gas entering the SCR catalytic reduction device.

[0028] Preferably, the main smoke guide pipe is provided with an orifice flowmeter for monitoring the flow of flue gas in the main smoke guide pipe;

[0029] The bypass smoke guide pipe is provided with a gas flowmeter for monitoring the flow of flue gas in the bypass smoke guide pipe;

[0030] The pressure transmitter is installed on the main flue pipe and used for monitoring the gas pressure of the flue gas in the main flue pipe.

[0031] The main flue pipe is provided with a nitrogen oxygen sensor detection point near one end of the SCR catalytic reduction device, which is used for detecting the nitrogen oxide content of the flue gas before treatment, and comparing and calculating the nitrogen oxide content of the flue gas detected by the nitrogen oxygen sensor detection point at the rear end of the SCR catalytic reduction device to control the spraying amount of urea.

[0032] Compared with the prior art, the beneficial effects of the utility model are:

[0033] 1. The front baffle valve, the rear baffle valve and the four-way reversing valve are arranged in the nitrogen oxide treatment equipment in the flue gas of the heat treatment workshop, and 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, the multiple operation modes of the nitrogen oxide treatment equipment can be realized.

[0034] 2. The combined flue pipe is arranged in the nitrogen oxide treatment equipment in the flue gas of the heat treatment workshop, when the flue gas flow in the total flue pipe is large, the flue gas enters the SCR catalytic reduction device through the main flue pipe with a large diameter, and when the flue gas flow in the total flue pipe is small, the flue gas enters the SCR catalytic reduction device through the bypass flue pipe with a small diameter, so that the flow rate of the flue gas entering the SCR catalytic reduction device is always ensured.

[0035] 3. The nitrogen oxide treatment equipment in the flue gas of the heat treatment workshop of the utility model can realize the switching of the four modes of normal, debugging, exceeding and pipe emptying, so as to meet the switching use in the four scenes of the flue gas catalytic reduction treatment, the equipment debugging under the state that the heat treatment furnace does not stop, the improvement of the concentration of indoor nitrogen oxide, the detection of the catalytic reduction effect of the SCR catalytic reduction device during debugging, the rapid emptying of the flue gas in the pipeline and the maintenance of the equipment. BRIEF DESCRIPTION OF DRAWINGS

[0036] Figure 1 It is the structural schematic view of the nitrogen oxide treatment equipment in the flue gas of the heat treatment workshop provided by the utility model;

[0037] Figure 2 It is the top view of the nitrogen oxide treatment equipment in the flue gas of the heat treatment workshop provided by the utility model;

[0038] Figure 3 It is the front view of the nitrogen oxide treatment equipment in the flue gas of the heat treatment workshop provided by the utility model;

[0039] Figure 4 It is the side view of the nitrogen oxide treatment equipment in the flue gas of the heat treatment workshop provided by the utility model;

[0040] Figure 5is a structural schematic view of the four-way reversing valve provided by the present application;

[0041] Figure 6 is a front view of the four-way reversing valve provided by the present application;

[0042] Figure 7 is a side view of the four-way reversing valve provided by the present application;

[0043] Figure 8 is an internal structure view of the four-way reversing valve provided by the present application;

[0044] Figure 9 is a structural schematic view of the back baffle valve provided by the present application;

[0045] Figure 10 is a sectional view of the back baffle valve provided by the present application;

[0046] Figure 11 is a structural schematic view of the front baffle valve provided by the present application;

[0047] Figure 12 is a structural schematic view of the SCR catalytic reduction device provided by the present application;

[0048] Figure 13 is a top view of the SCR catalytic reduction device provided by the present application;

[0049] Figure 14 is an internal structure schematic view of the SCR catalytic reduction device provided by the present application;

[0050] Figure 15 is a structural schematic view of the combined smoke guide pipe provided by the present application;

[0051] Figure 16 is a flow direction diagram of flue gas in a normal mode provided by the present application;

[0052] Figure 17 is a flow direction diagram of flue gas in a debugging mode provided by the present application;

[0053] Figure 18 is a flow direction diagram of flue gas in an override mode provided by the present application;

[0054] Figure 19 is a flow direction diagram of flue gas in a pipe emptying mode provided by the present application.

[0055] Fig. 1: 1, total flue; 2, SCR catalytic reduction device; 3, fan; 4, front baffle valve; 5, four-way reversing valve; 6, rear end flue; 7, outdoor exhaust pipe; 8, indoor exhaust pipe; 9, rear baffle valve; 10, main flue; 11, bypass flue; 12, first electric butterfly valve; 13, second electric butterfly valve; 14, orifice flowmeter; 15, gas flowmeter; 16, pressure transmitter; 17, nitrogen oxygen sensor detection point;

[0056] 201, static mixing zone; 202, flue gas heating zone; 203, SCR reaction zone; 2011, urea nozzle; 2021, heating pipe; 2031, catalyst carrier;

[0057] 401, outer channel;

[0058] 501, cylindrical valve body; 502, flue connection; 503, reversing valve plate; 504, drive shaft; 505, drive cylinder;

[0059] 901, baffle valve body; 902, air inlet; 903, air outlet; 904, baffle valve plate; 905, valve plate cylinder. DETAILED DESCRIPTION

[0060] The utility model will be made further detailed description in combination with the drawings and specific embodiments. According to the following description and claims, the advantages and features of the utility model will be more clear. It should be noted that the drawings all adopt very simplified form and all use non-precise proportion, only to facilitate, clear and assist the purpose of describing the embodiment of the utility model.

[0061] In the description of the utility model, it needs to be understood that the orientation or position relationship indicated by the terms "center", "longitudinal", "transverse", "upper", "lower", "front", "rear", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", "outer" and the like is based on the orientation or position relationship shown in the drawings, and is only for the convenience of describing the utility model and simplifying the description, and therefore cannot be understood as indicating or implying that the indicated device or element must have a particular orientation, be constructed and operated in a particular orientation, and therefore cannot be understood as a limitation on the utility model. In addition, the terms "first", "second" and the like are only for the purpose of description, and cannot be understood as indicating or implying relative importance or implicitly indicating the number of the indicated technical features. Therefore, the features limited by "first", "second" and the like can explicitly or implicitly include one or more features. In the description of the utility model, unless otherwise stated, the meaning of "multiple" is two or more.

[0062] In the description of the utility model, it is necessary to explain, unless another explicit provision and limitation, term "installation", "link", "connection" should do broad sense understanding, for example, can be fixed connection, also can be detachable connection, or integrally connected;Can be mechanical connection, also can be electrical connection;Can be directly connected, also can be indirectly connected through intermediate medium, can be two elements inside the communication.For ordinary skilled in the art, the above-mentioned terms can be understood by the specific meaning in the utility model through specific circumstances.

[0063] Embodiment one

[0064] The utility model provides a kind of nitrogen oxides treatment equipment in heat treatment workshop flue gas, please refer to Figures 1-4 Including total flue pipe 1 and by smoke pipe in turn with the front baffle valve 4 of total flue pipe 1, fan 3, SCR catalytic reduction device 2, four-way reversing valve 5 and rear baffle valve 9;The fan 3 in the total flue pipe 1 Smoke gas is introduced into the SCR catalytic reduction device 2 by the front baffle valve 4;The four-way reversing valve 5 has four smoke pipe interfaces, first smoke pipe interface is communicated with the total flue pipe 1, second smoke pipe interface is communicated with the rear end smoke pipe 6 of SCR catalytic reduction device 2, third smoke pipe interface is communicated with outdoor discharge pipe 7, fourth smoke pipe interface is communicated with indoor discharge pipe 8;The rear baffle valve 9 is installed on the indoor discharge pipe 8, for controlling the on-off of smoke gas in the indoor discharge pipe 8;The four-way reversing valve 5 has at least two gears, by switching different gears, realize the multiple operating modes of nitrogen oxides treatment equipment.

[0065] Specifically, please refer to Figures 5-7 The four-way reversing valve 5 includes barrel type valve body 501, four smoke pipe interfaces 502 are provided on the side wall of the barrel type valve body 501 and communicated with the inner cavity of the barrel type valve body 501, and a reversing valve plate 503 is arranged in the barrel type valve body 501, and the reversing valve plate 503 is rotationally connected with the barrel type valve body 501 through a drive shaft 504.

[0066] Further, the four-way reversing valve 5 is further provided with a drive cylinder 505, and the drive cylinder 505 is connected with the drive shaft 504 through a crank connecting rod, and with the extension and contraction of the piston rod of the drive cylinder 505, the crank connecting rod drives the drive shaft 504 and the reversing valve plate 503 connected with the drive shaft 504 to rotate, so as to switch different gears of the four-way reversing valve 5.

[0067] Further, as Figure 8As shown, the four-way reversing valve 5 has two gears, A and B gears respectively; one of the smoke pipe interfaces 502 of the four-way reversing valve 5 is always in communication with 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 drive cylinder 505 to switch between the A and B gears, thereby communicating two of the other three smoke pipe interfaces 502.

[0068] Specifically, please refer to Figure 9 and Figure 10 The rear baffle valve 9 includes a baffle valve body 901, a bottom air inlet 902 of the baffle valve body 901, and a plurality of air outlets 903 formed in the side wall; and a baffle valve plate 904 in the baffle valve body 901 is lifted up and down under the action of a valve plate cylinder 905.

[0069] When the baffle valve plate 904 is lowered to the lower sealing ring, the rear baffle valve 9 is closed; when the baffle valve plate 904 is raised to the upper sealing ring, the rear baffle valve 9 is opened.

[0070] Specifically, please refer to Figure 11 The front baffle valve 4 is installed on the smoke guide pipe between the total smoke pipe 1 and the fan 3, for controlling the on-off of the flue gas in the smoke guide pipe; the front baffle valve 4 is also provided with an outer passage 401; when the front baffle valve 4 is in the open state, the fan 3 introduces the flue gas in the total smoke pipe 1 into the SCR catalytic reduction device 2; when the front baffle valve 4 is in the closed state, the fan 3 introduces external air into the SCR catalytic reduction device 2 through the outer passage 401.

[0071] Specifically, please refer to Figures 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 arranged in sequence along the flue gas flow direction.

[0072] The static mixing zone 201 is provided with a urea spray head 2011 for spraying urea as a reducing agent to mix with flue gas.

[0073] In some embodiments, the urea spray head 2011 is provided with two groups, one of which normally sprays urea, and the other of which is standby.

[0074] The flue gas heating zone 202 is provided with a plurality of heating pipes 2021 arranged in sequence along the flue gas flow direction, for heating the flue gas by the heating pipes 2021.

[0075] The SCR reaction zone 203 is provided with a catalyst carrier 2031, under the action of the SCR catalyst, urea is decomposed and chemically reacts with nitrogen oxides, effectively reducing harmful substances in the flue gas.

[0076] Specifically, refer to Figure 15 The SCR catalytic reduction device 2 is connected with the fan 3 through a combined smoke guide pipe, the combined smoke guide pipe comprises a main smoke guide pipe 10 and a bypass smoke guide pipe 11, the pipe diameter of the main smoke guide pipe 10 is larger than that 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 communicated with the SCR catalytic reduction device 2 and the fan 3 respectively, and both can introduce flue gas from the fan 3 into the SCR catalytic reduction device 2.

[0077] The end of the main smoke guide pipe 10 close to the fan 3 is provided with a first electric butterfly valve 12 for controlling the on-off of flue gas in the main smoke guide pipe 10, and the end of the bypass smoke guide pipe 11 close to the fan 3 is provided with a second electric butterfly valve 13 for controlling the on-off of flue gas in the bypass smoke guide pipe 11.

[0078] When the flue gas flow in the total smoke pipe 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 guide pipe 10; when the flue gas flow in the total smoke pipe 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 guide pipe 11, to ensure the flow rate of the flue gas entering the SCR catalytic reduction device 2.

[0079] Further, a perforated plate flowmeter 14 is installed on the main smoke guide pipe 10 for monitoring the flue gas flow in the main smoke guide pipe 10, a gas flowmeter 15 is installed on the bypass smoke guide pipe 11 for monitoring the flue gas flow in the bypass smoke guide pipe 11, and a pressure transmitter 16 is installed on the main smoke guide pipe 10 for monitoring the gas pressure of the flue gas in the main smoke guide pipe 10.

[0080] The end of the main smoke guide pipe 10 close to the SCR catalytic reduction device 2 is provided with a nitrogen oxide sensor detection point 17 for detecting the nitrogen oxide content of the flue gas before treatment, and the amount of urea spraying is controlled by comparing and calculating 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.

[0081] When the nitrogen oxide treatment equipment for flue gas in a heat treatment workshop is used, firstly, the flue gas collecting pipes of multiple heat treatment furnaces are connected to the total smoke pipe 1, and two branch pipes are connected to the total smoke pipe 1, one branch pipe is connected to the front baffle valve 4, and the other branch pipe is connected to the four-way reversing valve 5; by controlling the on-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.

[0082] 1. Normal mode, used for flue gas catalytic reduction treatment in a normal state, such asFigure 16 As shown in the mode, the front baffle valve 4 is in the open state, the rear baffle valve 9 is in the closed state, and the four-way reversing valve 5 is switched to B gear; the flue gas in the total flue 1 is introduced into the SCR catalytic reduction device 2 under the action of the fan 3 through the front baffle valve 4 and the combined smoke guide pipe, and then discharged outdoor through the four-way reversing valve 5; when the flue gas enters the SCR catalytic reduction device 2, it is first mixed with the urea sprayed by the urea nozzle 2011 in the static mixing zone 201, then heated in the multiple heating pipes 2021 of the flue gas heating zone 202, and then chemically reacted 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; when the flue gas flow and pressure values monitored by the orifice flow meter 14 and the pressure transmitter 16 are less than the rated value, the first electric butterfly valve 12 is closed while 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 improve 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; 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 while 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 smoke guide pipe 10 to reduce the flow rate of the flue gas entering the SCR catalytic reduction device 2, thereby improving the effect of catalytic reduction reaction.

[0083] 2. Debugging mode, equipment debugging is carried out under the condition that the heat treatment furnace does not stop; as shown in Figure 17 As shown in the mode, the front baffle valve 4 is in the closed state, the rear baffle valve 9 is in the open state, and the four-way reversing valve 5 is switched to A gear; under the action of the fan 3, the indoor air is introduced into the SCR catalytic reduction device 2, and then discharged indoor through the four-way reversing valve 5 and the rear baffle valve 9, while the flue gas in the total flue 1 is discharged outdoor through the four-way reversing valve 5.

[0084] 3. Overrun mode, under the condition that the heat treatment furnace does not stop, the concentration of indoor nitrogen oxides is improved to detect the catalytic reduction effect of the SCR catalytic reduction device 2 during debugging; as shown in Figure 18 As shown in the mode, the front baffle valve 4 is in the closed state, the rear baffle valve 9 is in the open state, and the four-way reversing valve 5 is switched to B gear; under the action of the fan 3, the indoor air is introduced into the SCR catalytic reduction device 2, and then discharged outdoor through the four-way reversing valve 5, while the flue gas in the total flue 1 is discharged indoor through the four-way reversing valve 5 and the rear baffle valve 9.

[0085] 4. Pipe emptying mode, quickly emptying the flue gas in the pipeline for equipment maintenance; as shown in Figure 19As shown, in this mode, the front baffle valve 4 is in the open state, the rear baffle valve 9 is in the open state, and the four-way reversing valve 5 is switched to the A gear; the flue gas in the total flue 1 is introduced into the SCR catalytic reduction device 2 under the action of the fan 3 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 total flue 1 is discharged outdoors through the four-way reversing valve 5.

[0086] The heat treatment workshop flue gas nitrogen oxide treatment equipment can realize the switching of four modes of normal, debugging, exceeding and pipe emptying, thereby meeting the switching use in four scenes of flue gas catalytic reduction treatment, equipment debugging under the condition that the heat treatment furnace does not stop, improving the concentration of indoor nitrogen oxide, detecting the catalytic reduction effect of the SCR catalytic reduction device during debugging, quickly emptying the flue gas in the pipeline, and maintaining the equipment.

[0087] The above description is only a description of the preferred embodiment of the utility model, and does not limit the scope of the utility model, and any change and modification of the above disclosure by the ordinary skilled in the art belongs to the protection scope of the claims.

Claims

1. A plant for the treatment of nitrogen oxides in the off-gas of a heat treatment plant, characterized in that, The total flue (1) and the front baffle valve (4), the fan (3), the SCR catalytic reduction device (2), the four-way reversing valve (5) and the rear baffle valve (9) are connected in sequence through the flue guide pipe; The fan (3) introduces the flue gas in the total flue (1) into the SCR catalytic reduction device (2) through the front baffle valve (4); The four-way reversing valve (5) has four flue interfaces, the first flue interface is communicated with the total flue (1), the second flue interface is communicated with the rear-end flue guide pipe (6) of the SCR catalytic reduction device (2), the third flue interface is communicated with the outdoor exhaust pipe (7), and the fourth flue interface is communicated with the indoor exhaust pipe (8); The rear baffle valve (9) is installed on the indoor exhaust pipe (8) and is used for controlling the on-off of the flue gas in the indoor exhaust pipe (8); The four-way reversing valve (5) has at least two gears, and different gears are switched to realize multiple operation modes of the nitrogen oxide treatment equipment.

2. A plant for the treatment of nitrogen oxides in the fumes of a thermal treatment plant according to claim 1, characterized in that, The four-way reversing valve (5) comprises a cylindrical valve body (501), four flue interfaces (502) are arranged on the side wall of the cylindrical valve body (501) and communicated with the inner cavity of the cylindrical valve body (501), and a reversing valve plate (503) is arranged in the cylindrical valve body (501), and the reversing valve plate (503) is rotationally connected with the cylindrical valve body (501) through a driving shaft (504) in the middle.

3. A plant for the treatment of nitrogen oxides in the fumes of a thermal treatment plant according to claim 2, characterised in that, The four-way reversing valve (5) is further provided with a driving cylinder (505), the telescopic rod of the driving cylinder (505) is connected with the driving shaft (504) through a crank connecting rod, and the driving shaft (504) and the reversing valve plate (503) connected with the driving shaft (504) are driven to rotate by the crank connecting rod with the telescopic rod of the driving cylinder (505), so that different gears of the four-way reversing valve (5) are switched.

4. A plant for the treatment of nitrogen oxides in the flue gases of a heat treatment plant according to claim 3, characterised in that, The four-way reversing valve (5) has two gears, A gear and B gear. One of the flue interfaces (502) of the four-way reversing valve (5) is always communicated with the rear-end flue guide pipe (6) of the SCR catalytic reduction device (2), and the reversing valve plate (503) is rotated by 90 degrees under the action of the driving cylinder (505) to switch between the A gear and the B gear, so that two of the other three flue interfaces (502) are communicated.

5. A plant for the treatment of nitrogen oxides in the fumes of a thermal treatment plant according to claim 1, characterized in that, The rear baffle valve (9) comprises a baffle valve body (901), an air inlet (902) is arranged at the bottom of the baffle valve body (901), a plurality of air outlets (903) are arranged on the side wall of the baffle valve body (901), and a baffle valve plate (904) in the baffle valve body (901) is lifted up and down under the action of a valve plate cylinder (905); When the baffle valve plate (904) goes down to the lower sealing ring, the rear baffle valve (9) is closed; When the baffle valve plate (904) goes up to the upper sealing ring, the rear baffle valve (9) is opened.

6. A plant for the treatment of nitrogen oxides in the fumes of a thermal treatment plant according to claim 1, characterized in that, The front baffle valve (4) is installed on the flue guide pipe between the total flue (1) and the fan (3) and is used for controlling the on-off of the flue gas in the flue guide pipe. An outer passage (401) is further formed on the front baffle valve (4); when the front baffle valve (4) is in an open state, the fan (3) introduces flue gas in the total flue pipe (1) into the SCR catalytic reduction device (2); 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 outer passage (401).

7. A plant for the treatment of nitrogen oxides in the fumes of a thermal treatment plant according to claim 1, characterized in that, The SCR catalytic reduction device (2) comprises a static mixing area (201), a flue gas heating area (202) and an SCR reaction area (203) arranged in sequence along a flue gas flow direction; The static mixing area (201) is provided with a urea nozzle (2011) for spraying urea as a reducing agent to mix with flue gas; The flue gas heating area (202) is provided with a plurality of heating pipes (2021) arranged in sequence along the flue gas flow direction, and the heating pipes (2021) are used for heating flue gas; The SCR reaction area (203) is provided with a catalyst carrier (2031), and under the action of an SCR catalyst, urea is decomposed and chemically reacts with nitrogen oxides to effectively reduce harmful substances in flue gas.

8. A plant for the treatment of nitrogen oxides in the fumes of a thermal treatment plant according to claim 1, characterized in that, The SCR catalytic reduction device (2) and the fan (3) are connected through a combined smoke guide pipe, the combined smoke guide pipe comprises a main smoke guide pipe (10) and a bypass smoke guide pipe (11), the pipe diameter of the main smoke guide pipe (10) is larger than that 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 flue gas from the fan (3) into the SCR catalytic reduction device (2).

9. A plant for the treatment of nitrogen oxides in the flue gases of a thermal treatment plant according to claim 8, characterised in that, A first electric butterfly valve (12) is arranged at one end of the main smoke guide pipe (10) close to the fan (3) and is used for controlling the on-off of flue gas in the main smoke guide pipe (10); a second electric butterfly valve (13) is arranged at one end of the bypass smoke guide pipe (11) close to the fan (3) and is used for controlling the on-off of flue gas in the bypass smoke guide pipe (11); When the flue gas flow in the total flue pipe (1) is large, the first electric butterfly valve (12) is opened and the second electric butterfly valve (13) is closed, so that flue gas is introduced from the main smoke guide pipe (10) into the SCR catalytic reduction device (2); when the flue gas flow in the total flue pipe (1) is small, the first electric butterfly valve (12) is closed and the second electric butterfly valve (13) is opened, so that flue gas is introduced from the bypass smoke guide pipe (11) into the SCR catalytic reduction device (2), to ensure the flow rate of flue gas entering the SCR catalytic reduction device (2).

10. A plant for the treatment of nitrogen oxides in the fumes of a thermal treatment plant according to claim 9, characterized in that, A perforated plate flowmeter (14) is installed on the main smoke guide pipe (10) and is used for monitoring the flow of flue gas in the main smoke guide pipe (10); A gas flowmeter (15) is installed on the bypass smoke guide pipe (11) and is used for monitoring the flow of flue gas in the bypass smoke guide pipe (11); A pressure transmitter (16) is installed on the main smoke guide pipe (10) and is used for monitoring the gas pressure of flue gas in the main smoke guide pipe (10); The main flue duct (10) is provided with a nitrogen oxygen sensor detection point (17) near one end of the SCR catalytic reduction device (2), which is used for detecting the nitrogen oxide content of flue gas before treatment, and the urea spraying amount is controlled after comparison and calculation of the nitrogen oxide content of flue gas detected by the nitrogen oxygen sensor detection point at the rear end of the SCR catalytic reduction device (2).

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