Accurate ammonia spraying device for flue gas denitration system of thermal power generating unit

Abstract

The invention relates to the field of flue gas denitration, and discloses a thermal power generating unit flue gas denitration system precise ammonia spraying device, which comprises a plurality of storage pipes, the plurality of storage pipes are arranged on the inner wall of a flue, the plurality of storage pipes are mutually communicated, the outer walls of the storage pipes are fixedly communicated with ammonia spraying grids, and the ammonia spraying grids are communicated with the storage pipes. The ammonia spraying grid is rotatably arranged on the inner wall of the flue, a PLC is fixed to the right side of the flue, a plurality of nozzles are fixed to the end of the ammonia spraying grid, a connecting shaft is fixed to the right side of the storage pipe, and the connecting shaft extends to the right side of the flue. According to the device, through the synergistic effect of a connecting shaft, a rotating disc, a tooth groove, a driving motor and a gear, precise angular displacement regulation and control can be implemented on the ammonia spraying grid, then precise positioning of the space spraying angle and position of a spraying head is achieved, it can be ensured that an ammonia spraying track and a flue gas flow field form an optimal coupling state, and the spraying effect is improved. And the reducing agent is spatially and uniformly distributed in the flue.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of flue gas denitration, in particular to a precise ammonia injection device for a flue gas denitration system of a thermal power generating unit. BACKGROUND

[0002] Nitrogen oxides (NOx) are a major atmospheric pollutant and one of the main factors in the formation of acid rain, photochemical smog, and PM2.5 pollution. In industrial flue gas treatment, common NOx emission control technologies include selective catalytic reduction (SCR), selective non-catalytic reduction (SNCR), and SCR-SNCR hybrid technologies. The selective catalytic reduction (SCR) technology has the characteristics of high efficiency, no secondary pollution, and mature technology, and is widely used in large coal-fired units. With the large-scale grid connection of photovoltaic power generation and wind power generation, thermal power generating units have shifted from bearing basic load to flexible operation. Frequent start-stop and rapid load change of the units have a negative impact on the flue gas denitration system, and phenomena such as excessive or insufficient ammonia injection easily occur. If the ammonia injection is excessive, the ammonia escape amount of the flue gas denitration system is large, the operation cost is high, and phenomena such as blockage and corrosion of the air preheater, and jamming of the induced draft fan due to dust accumulation easily occur, affecting the load carrying capacity of the unit and threatening the safe and stable operation of the unit. If the ammonia injection is insufficient, the concentration of nitrogen oxides emitted in the flue gas is high, and the environmental protection requirements cannot be met.

[0003] A flue gas denitration system for a thermal power generating unit is disclosed in Chinese Patent No. CN216799381U, which includes a flue with a π-shaped arrangement. The flue has three bends, which are a first bend, a second bend, and a third bend in the order of the flue gas flow direction. An ammonia injection grid, a mixer, a flow guide device, a rectifying device, a catalytic device, and a NOx measuring device are arranged in the flue in the order of the flue gas flow direction. The ammonia injection grid and the mixer are located between the first bend and the second bend, and the flow guide device is located in the third bend.

[0004] In the above scheme, by introducing a feedforward control, the ammonia injection amount can be adjusted in advance, so that the ammonia escape amount is small. However, the fixed-angle ammonia injection grid cannot adapt to the dynamic changes of the flue gas flow field in the flue, causing imbalance in the local mixing of ammonia gas and flue gas, and easily forming a phenomenon of coexistence of over-injection and under-injection zones, leading to an increase in systematic ammonia escape. SUMMARY

[0005] The present application aims to provide a precise ammonia injection device for a flue gas denitration system of a thermal power generating unit to solve the problem of fixed-angle ammonia injection grid that cannot adapt to the dynamic changes of the flue gas flow field in the flue, causing imbalance in the local mixing of ammonia gas and flue gas, and easily forming a phenomenon of coexistence of over-injection and under-injection zones, leading to an increase in systematic ammonia escape.

[0006] In order to achieve the above-mentioned purpose of the application, the following technical scheme is adopted: the precise ammonia spraying device of the flue gas denitration system of the thermal power generating unit, comprising a plurality of storage tubes, the plurality of storage tubes are arranged on the inner wall of the flue, the plurality of storage tubes are interconnected, the outer wall of the storage tube is fixedly connected with an ammonia spraying grid, the ammonia spraying grid is rotatably arranged on the inner wall of the flue, a PLC controller is fixedly arranged on the right side of the flue, a plurality of nozzles are fixedly arranged on the end of the ammonia spraying grid, a connecting shaft is fixedly arranged on the right side of the storage tube, the connecting shaft extends to the right side of the flue, a rotating disc is fixedly arranged on the other end of the connecting shaft, a tooth groove is arranged on the outer wall of the rotating disc, an installation groove is arranged on the right side of the flue, a driving motor is connected to the inner wall of the installation groove, a gear is fixedly arranged on one end of the output shaft of the driving motor, the gear is engaged with the tooth groove, and the driving motor is electrically connected with the PLC controller.

[0007] Preferably, a scale line is arranged on the right side of the flue, and a pointing mark is fixedly arranged on the rotating disc and corresponds to the scale line.

[0008] Preferably, a filter box is fixedly arranged on the top surface of the flue, a connecting hose is fixedly and communicatively arranged on the bottom surface of the filter box, the connecting hose extends into the flue and is connected with the storage tube, an air inlet pipe is fixedly and communicatively arranged on the left side of the filter box, the air inlet pipe is connected with the output end of an external ammonia conveying device, a through hole is arranged on the top surface of the filter box, an installation frame is clamped on the inner wall of the through hole, and a filter screen is fixedly arranged on the inner wall of the installation frame.

[0009] Preferably, a sealing ring is fixedly arranged on the outer wall of the installation frame and is in contact with the inner wall of the through hole.

[0010] Preferably, a plurality of installation holes are arranged on the inner wall of the flue, a first monitoring module is fixedly arranged on the inner wall of the installation hole, and the first monitoring module is electrically connected with the PLC controller.

[0011] Preferably, a fixing hole is arranged on the top surface of the flue, a second monitoring module is fixedly arranged on the inner wall of the fixing hole, and the second monitoring module is electrically connected with the PLC controller.

[0012] Compared with the prior art, the present application has the following beneficial effects: One, through the coordinated action of the connecting shaft, rotating disc, gear slot, drive motor and gear, the precise angular displacement control of the ammonia injection grid can be realized, and then the precise positioning of the space injection angle and position of the nozzle can be realized, which can ensure that the ammonia injection trajectory and the flue gas flow field form the optimal coupling state, so that the reducing agent realizes the uniform distribution in the flue, greatly improves the gas and smoke mixing efficiency, effectively prevents local over-injection or under-injection caused by uneven ammonia injection, and significantly improves the stability and reliability of the entire denitration system. Through the coordinated action of the pointing mark and the scale line, the operator can easily understand the specific position of the nozzle, which helps to accurately adjust the ammonia injection direction and angle, and ensures the uniformity and accuracy of ammonia injection; Two, the ammonia entering the storage pipe can be filtered through the filter screen to remove impurities and particulate matter, preventing these impurities from clogging the nozzle or affecting the denitration reaction, ensuring the purity of the ammonia and the normal operation of the ammonia injection system, reducing the probability of equipment failure, and improving the stability and reliability of the entire denitration system. The sealing ring can increase the sealing between the mounting frame and the through hole, effectively preventing ammonia from leaking from the through hole on the top surface of the filter box, ensuring that all ammonia enters the storage pipe through the connecting hose, improving the utilization rate of ammonia, and also avoiding the harm caused by ammonia leakage to the environment and personnel; Three, the first monitoring module can monitor the nitrogen oxide concentration, flow and temperature of the flue gas in the flue in real time, providing accurate data support for the PLC controller, so as to adjust the ammonia injection amount and angle according to the actual working condition, which can make the ammonia injection system adjust in time according to the change of flue gas, ensure the denitration efficiency and the control effect of ammonia escape. The double-light-path ammonia escape monitor can accurately monitor the ammonia escape in the flue, timely detect the change of ammonia escape amount, and timely adjust the ammonia injection amount through real-time monitoring of the ammonia escape amount, which can ensure the denitration efficiency while minimizing ammonia escape, reducing the waste of ammonia and pollution to the environment, and also reducing the equipment corrosion and maintenance cost caused by ammonia escape. BRIEF DESCRIPTION OF DRAWINGS

[0013] Figure 1 It is a three-dimensional schematic view of the embodiment.

[0014] Figure 2 It is a split schematic view of the embodiment.

[0015] Figure 3 It is a split schematic view of the filter box and the mounting frame of the embodiment.

[0016] Figure 4 It is a Figure 2 It is an enlarged schematic view of position A of the embodiment.

[0017] In the figure: 1, storage tube; 2, flue; 3, ammonia injection grid; 4, spray head; 5, connecting shaft; 6, rotating disc; 7, tooth groove; 8, mounting groove; 9, driving motor; 10, gear; 11, scale line; 12, pointer; 13, filter box; 14, air inlet pipe; 15, through hole; 16, mounting frame; 17, filter screen; 18, sealing ring; 19, mounting hole; 20, first monitoring module; 21, fixing hole; 22, second monitoring module. DETAILED DESCRIPTION

[0018] The preferred embodiments of the present application will be described in detail below with reference to the drawings.

[0019] As Figures 1-4 shown, the precise ammonia injection device of the flue gas denitrification system of the thermal power generating unit comprises a plurality of storage tubes 1, the plurality of storage tubes 1 are all arranged on the inner wall of the flue 2, the plurality of storage tubes 1 are interconnected, the outer wall of the storage tube 1 is fixedly connected with the ammonia injection grid 3, the ammonia injection grid 3 is rotatably arranged on the inner wall of the flue 2, the right side of the flue 2 is fixedly connected with the PLC controller, the end of the ammonia injection grid 3 is fixedly connected with a plurality of spray heads 4, the right side of the storage tube 1 is fixedly connected with the connecting shaft 5, the connecting shaft 5 extends to the right side of the flue 2, the other end of the connecting shaft 5 is fixedly connected with the rotating disc 6, the outer wall of the rotating disc 6 is provided with the tooth groove 7, the right side of the flue 2 is provided with the mounting groove 8, the inner wall of the mounting groove 8 is connected with the driving motor 9, one end of the output shaft of the driving motor 9 is fixedly connected with the gear 10, the gear 10 is engaged with the tooth groove 7, the driving motor 9 is electrically connected with the PLC controller, the right side of the flue 2 is provided with the scale line 11, the rotating disc 6 is fixedly connected with the pointer 12, the right side of the flue 2 is provided with the scale line 11 corresponding to the pointer 12, the rotating disc 6 is fixedly connected with the pointer 12 corresponding to the scale line 11.

[0020] In use, when the angle of the ammonia injection grid 3 needs to be adjusted, the operation process is as follows: first, the operator starts the driving motor 9 through the PLC controller, the driving motor 9 outputs the torque to drive the gear 10 to rotate, the gear 10 is engaged with the tooth groove 7 on the outer wall of the rotating disc 6 to drive the rotating disc 6 to produce angular displacement, and then the rotating motion is transmitted to the ammonia injection grid 3 through the connecting shaft 5 to realize the angle adjustment of the ammonia injection grid 3 on the inner wall of the flue 2, in this process, the pointer 12 on the rotating disc 6 and the scale line 11 on the right side of the flue 2 form a visual angle indicating system to provide real-time angle feedback for the operator; When the ammonia injection grid 3 and the rotating disc 6 reach the preset angle position, the driving motor 9 is turned off to lock the current angle, and then the external ammonia conveying equipment is started, ammonia gas enters the filter box 13 through the gas inlet pipe 14, and the impurities and particulate matter are intercepted and purified through the filter screen 17 in the mounting frame 16, the purified ammonia gas is conveyed into the storage pipe 1 through the connecting hose, and then is distributed by the ammonia injection grid 3 and is precisely injected into the flue gas flow field at the inlet of the flue 2 by the spray head 4, through the angle precise control and the synergistic effect of ammonia gas purification pretreatment, the uniform distribution of the reducing agent in the flue gas is ensured, and the optimal conditions for the catalytic reduction reaction in the subsequent SCR reactor are created, thereby improving the denitration efficiency and inhibiting ammonia escape; Through the synergistic effect of the connecting shaft 5, the rotating disc 6, the gear slot 7, the driving motor 9 and the gear 10, the precise angle displacement control of the ammonia injection grid 3 can be realized, and then the precise positioning of the space injection angle and position of the spray head 4 can be realized, which can ensure that the ammonia injection trajectory and the flue gas flow field form an optimal coupling state, so that the reducing agent can be uniformly distributed in the flue 2, the gas and smoke mixing efficiency is greatly improved, the local over-injection or under-injection caused by uneven ammonia injection is effectively prevented, and the stability and reliability of the entire denitration system are significantly improved. Through the synergistic effect of the pointing mark 12 and the scale line 11, the specific position of the spray head 4 can be easily understood by the operator, which is helpful for precise adjustment of the ammonia injection direction and angle, and ensures the uniformity and accuracy of the ammonia injection.

[0021] As shown in Figures 1-4 , the top surface of the flue 2 is fixed with the filter box 13, the bottom surface of the filter box 13 is fixed with the connecting hose in communication, the connecting hose extends into the flue 2 and is in communication with the storage pipe 1, the left side of the filter box 13 is fixed with the gas inlet pipe 14 in communication, the gas inlet pipe 14 is connected with the output end of the external ammonia conveying equipment, the top surface of the filter box 13 is provided with the through hole 15, the inner wall of the through hole 15 is clamped with the mounting frame 16, the inner wall of the mounting frame 16 is fixed with the filter screen 17, the outer wall of the mounting frame 16 is fixed with the sealing ring 18, and the sealing ring 18 is in contact with the inner wall of the through hole 15.

[0022] In use, the ammonia gas entering the storage pipe 1 can be filtered by the filter screen 17 to remove impurities and particulate matter, preventing these impurities from clogging the spray head 4 or affecting the denitration reaction, ensuring the purity of the ammonia gas and the normal operation of the ammonia injection system, reducing the probability of equipment failure, and improving the stability and reliability of the entire denitration system. The sealing ring 18 can increase the sealing between the mounting frame 16 and the through hole 15, effectively preventing ammonia gas from leaking from the through hole 15 on the top surface of the filter box 13, ensuring that all the ammonia gas enters the storage pipe 1 through the connecting hose, improving the utilization rate of ammonia gas, and avoiding the harm caused by ammonia gas leakage to the environment and personnel.

[0023] As shown in Figure 1 , Figure 2 , and Figure 4As shown, the inner wall of the flue 2 is provided with a plurality of mounting holes 19, the inner wall of the mounting hole 19 is fixed with the first monitoring module 20, the first monitoring module 20 includes but is not limited to concentration sensor, flue gas flow meter and thermometer, the first monitoring module 20 is electrically connected with the PLC controller, the top surface of the flue 2 is provided with a fixing hole 21, the inner wall of the fixing hole 21 is fixed with the second monitoring module 22, the second monitoring module 22 is electrically connected with the PLC controller, and the second monitoring module 22 is a double optical path ammonia escape monitor.

[0024] In use, the first monitoring module 20 can monitor the nitrogen oxide concentration, flow and temperature and other parameters of the flue gas in the flue 2 in real time, provide accurate data support for the PLC controller, so as to adjust the ammonia injection amount and the ammonia injection angle according to the actual working condition, so that the ammonia injection system can be adjusted in time according to the change of the flue gas, ensure the denitration efficiency and the control effect of ammonia escape. The double optical path ammonia escape monitor can accurately monitor the ammonia escape condition in the flue 2, discover the change of the ammonia escape amount in time, and adjust the ammonia injection amount in time through real-time monitoring of the ammonia escape amount, so as to maximize the reduction of ammonia escape while ensuring the denitration efficiency, reduce the waste of ammonia gas and the pollution to the environment, and also reduce the equipment corrosion and maintenance cost caused by ammonia escape.

[0025] The above is only the preferred specific embodiment of the present application, but the protection scope of the present application is not limited to this, any person skilled in the art can make equivalent replacement or change according to the technical scheme and the inventive concept of the present application within the technical range disclosed by the present application, which should be covered in the protection scope of the present application.

Claims

1. A precise ammonia injection device for a flue gas denitration system of a thermal power unit, comprising a plurality of storage tubes (1), wherein each of the plurality of storage tubes (1) is arranged on an inner wall of a flue (2), and characterized in that, If a plurality of said storage tube (1) between each other, the outer wall of the storage tube (1) is fixed with ammonia grid (3), the ammonia grid (3) can be rotated in the inner wall of the flue (2), the right side of the flue (2) is fixed with PLC controller, the end of the ammonia grid (3) is fixed with a plurality of spray head (4), the right side of the storage tube (1) is fixed with connecting shaft (5), the connecting shaft (5) extends to the right side of the flue (2), the other end of the connecting shaft (5) is fixed with rotating disc (6), the outer wall of the rotating disc (6) is provided with a gear slot (7), the right side of the flue (2) is provided with mounting groove (8), the inner wall of the mounting groove (8) is connected with drive motor (9), the output shaft of the drive motor (9) is fixed with gear (10) on one end, the gear (10) is engaged with the gear slot (7), the drive motor (9) is electrically connected with the PLC controller.

2. The precise ammonia injection device for a flue gas denitration system of a thermal power unit according to claim 1, characterized in that: The right side of the flue (2) is provided with a scale line (11), the rotating disc (6) is fixed with a pointing mark (12), the pointing mark (12) corresponds to the scale line (11).

3. The precise ammonia injection device for flue gas denitration system of thermal power unit according to claim 2, characterized in that: The top surface of the flue (2) is fixed with a filter box (13), the bottom surface of the filter box (13) is fixed with a connecting hose, the connecting hose extends into the flue (2) and is connected with the storage tube (1), the left side of the filter box (13) is fixed with an air inlet pipe (14), the air inlet pipe (14) is connected with the output end of the external ammonia conveying equipment, the top surface of the filter box (13) is provided with a through hole (15), the inner wall of the through hole (15) is clamped with a mounting frame (16), the inner wall of the mounting frame (16) is fixed with a filter screen (17).

4. The precise ammonia injection device for flue gas denitration system of thermal power unit according to claim 3, characterized in that: The outer wall of the mounting frame (16) is fixed with a sealing ring (18), the sealing ring (18) is in contact with the inner wall of the through hole (15).

5. The precise ammonia injection device for flue gas denitration system of thermal power unit according to claim 3, characterized in that: The inner wall of the flue (2) is provided with a plurality of mounting holes (19), the inner wall of the mounting hole (19) is fixed with a first monitoring module (20), the first monitoring module (20) is electrically connected with the PLC controller.

6. The precise ammonia injection device for flue gas denitration system of thermal power unit according to claim 5, characterized in that: The top surface of the flue (2) is provided with a fixing hole (21), the inner wall of the fixing hole (21) is fixed with a second monitoring module (22), the second monitoring module (22) is electrically connected with the PLC controller.

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