Intelligent precise ammonia spraying system for denitration

Abstract

The utility model discloses an intelligent and accurate ammonia spraying system for denitration. The system comprises a plurality of purification towers, and an ammonia branch and an air branch which are connected in parallel, are intersected on a main pipeline and are communicated with the purification towers through branch pipelines, the purification tower is provided with a nitrogen oxide analyzer; a dilution fan and a valve I are arranged on the air branch; a liquid ammonia tank, a water pump, a valve II, a flow meter II and a liquid ammonia evaporator are sequentially arranged on the ammonia branch; a mixer and a flowmeter III are arranged on the main pipeline; a valve III, a flow meter I and an air blower are arranged on each branch pipeline; the output ends of the nitrogen oxide analyzer and the flow meters are connected with a central control system; the output end of the central control system is connected with a PLC (Programmable Logic Controller); and the output end of the PLC is connected with the dilution fan, the water pump, the liquid ammonia evaporator, the mixer, the air blower and each valve. According to the utility model, on-line monitoring of environmental protection indexes, intelligent ammonia production and accurate ammonia spraying are realized, and the purposes of reducing the emission content of nitrogen oxides and saving the operation cost are achieved.

Description

Technical Field

[0001] The utility model relates to a denitration system, in particular to an intelligent and precise ammonia spraying system for denitration of flue gas at a sintering machine head. Background Art

[0002] The control of nitrogen oxides has always been the focus of environmental protection in most countries in the world. The pollutants produced by nitrogen oxides are one of the largest sources of pollution that cause ecological damage in my country, and have become a top priority for air pollution control in my country. Selective catalytic reduction (SCR) is the most widely used, most mature and most effective flue gas denitrification technology in the world. It specifically refers to the use of reducing agents (such as NH3, liquid ammonia, urea) to "selectively" react with nitrogen oxides in flue gas under the action of catalysts to generate non-toxic and non-polluting N2 and H2O.

[0003] A Chinese utility model patent with authorization announcement number CN202638255U discloses an in-furnace ammonia injection denitrification system, including a box body, in which a catalyst reaction device and a fluid correction device are arranged. The catalyst reaction device is arranged at the lower part of the fluid correction device. The catalyst reaction device includes multiple catalyst material layers and a catalyst internal anti-blocking device. The upper part of the fluid correction device is connected to an ammonia injection device.

[0004] Although the utility model patent has a simple system and little secondary pollution, it lacks monitoring means and needs to rely entirely on manual experience to adjust the amount of ammonia sprayed, which makes the operation difficult. In order to ensure that the flue gas emission data meets the standards, a large amount of ammonia water is usually required to be sprayed. Excessive ammonia water can easily lead to a large amount of NH4HSO3 and (NH4)2SO3 in the transition chamber, reducing the desulfurization performance of the circulating fluidized bed and easily leading to excessive ammonia concentration in the transition chamber. In addition to part of the ammonia consumed by the reaction with nitrogen oxides, excess ammonia overflows with the flue gas, increasing operating costs.

[0005] Therefore, inventing an intelligent and precise ammonia injection system for denitrification is an urgent problem to be solved by those skilled in the art. Utility Model Content

[0006] In order to solve the above technical problems, the utility model provides a denitrification intelligent precision ammonia spraying system, which realizes online monitoring of environmental protection indicators and intelligent control of precise ammonia spraying, thereby achieving the purpose of reducing nitrogen oxide emission content while saving operating costs.

[0007] In order to solve the above technical problems, the technical solution adopted by the utility model is: a denitrification intelligent precision ammonia spraying system, comprising a plurality of purification towers and an ammonia branch and an air branch which are connected in parallel to the main pipeline and then connected to each purification tower through branch pipelines; each of the purification towers is provided with a nitrogen oxide analyzer for measuring the nitrogen oxide concentration in the purification tower; the air branch is provided with a dilution fan and a valve I; the ammonia branch is provided with a liquid ammonia tank, a water pump, a valve II, a flowmeter II and a liquid ammonia evaporator in sequence; the main pipeline is provided with a mixer and a flowmeter III; each branch pipeline is provided with a valve III, a flowmeter I and a blower.

[0008] The output ends of the nitrogen oxide analyzer, flowmeter I, flowmeter II and flowmeter III are connected to the central control system; the output end of the central control system is connected to the PLC controller; the output end of the PLC controller is connected to the dilution fan, valve I, water pump, valve II, liquid ammonia evaporator, mixer, valve III and blower.

[0009] A further improvement of the technical solution of the utility model is that: an air inlet chamber and an air outlet chamber that are separated and not connected are arranged in the middle of the purification tower, and the air outlet chamber is connected to the chimney through a flue; two material chambers connected to the air inlet chamber and the air outlet chamber are arranged outside the air inlet chamber and the air outlet chamber; two transition air chambers connected to the material chamber are arranged outside the material chamber, and each branch pipeline is connected to the transition air chamber.

[0010] A further improvement of the technical solution of the utility model is that an ammonia spraying grid plate is arranged in the middle of the transition air chamber to fully mix the mixed gas of ammonia and air with nitrogen oxides.

[0011] A further improvement of the technical solution of the utility model is that: the output end of the PLC controller is also connected to an alarm.

[0012] Due to the adoption of the above technical solution, the technical progress achieved by the utility model is:

[0013] The utility model arranges a nitrogen oxide analyzer for measuring the concentration of nitrogen oxides in the transition air chamber of each purification tower, and connects the output end of the nitrogen oxide analyzer to the central control system, so that the content of nitrogen oxides is monitored in real time; a PLC controller is connected to the output end of the central control system, and the output end of the PLC controller is connected to the dilution fan on the air branch, the water pump and the liquid ammonia evaporator on the ammonia branch, the mixer on the main pipeline, the blower on the branch pipeline and the valves on each pipeline; when the system is working, each nitrogen oxide analyzer transmits the nitrogen oxide content in the air inlet chamber of each purification tower to the central control system, and the central control system calculates the amount of ammonia required for the entire system and each purification tower through data calculation, and then transmits it to the PLC controller, and the PLC controller turns on the dilution fan, the water pump, the liquid ammonia evaporator, the mixer and the blower as well as the valves, produces a proper amount of ammonia and mixes it with air, and then transmits it to the transition air chamber in each purification tower according to the amount, thereby realizing intelligent ammonia production and precise ammonia spraying.

[0014] The utility model provides an ammonia spraying grid plate at the middle position of the transition air chamber, which can better mix the mixed gas of ammonia and air with nitrogen oxides, thereby improving the utilization rate of liquid ammonia.

[0015] The output end of the PLC controller of the utility model is also connected to an alarm, which will give out an alarm immediately when a failure occurs in the system operation, so as to ensure that relevant personnel can conduct timely inspection and repair. BRIEF DESCRIPTION OF THE DRAWINGS

[0016] Figure 1 It is a schematic diagram of the structure of the utility model;

[0017] Figure 2 This is the control principle diagram of the utility model;

[0018] Figure 3 This is a schematic diagram of the internal structure of the purification tower of the utility model;

[0019] Among them, 1. Dilution fan; 2. Valve I; 3. Chimney; 4. Liquid ammonia tank; 5. Water pump; 6. Valve II; 7. Flow meter II; 8. Mixer; 9. Valve III; 10. Flow meter I; 11. Purification tower; 12. Nitrogen oxide analyzer; 13. Liquid ammonia evaporator; 14. Flow meter III; 15. Central control system; 16. PLC controller; 17. Alarm; 18. Blower; 19. Air inlet chamber; 20. Air outlet chamber; 21. Transition air chamber; 22. Ammonia spray grid plate. DETAILED DESCRIPTION

[0020] The present invention is further described in detail below in conjunction with the embodiments:

[0021] like Figure 1 As shown, a denitrification intelligent precision ammonia injection system includes an ammonia pipeline, an air branch, a main pipeline and a branch pipeline.

[0022] The ammonia branch is provided with a liquid ammonia tank 4 for providing an ammonia source, a water pump 5 for providing power, a valve II6 for controlling the switch of the ammonia branch, a liquid ammonia evaporator 13 for evaporating liquid ammonia into ammonia gas, and a flowmeter II7 for measuring the flow of the ammonia branch in sequence; the air branch is provided with a dilution fan 1 for providing an air source and a valve I2 for controlling the switch of the air branch; the ammonia branch and the air branch are connected in parallel and intersect at the main pipeline, and the main pipeline is provided with a mixer 8 for evenly mixing ammonia and air and a flowmeter III14 for measuring the flow of the main pipeline; the main pipeline is connected with the transition air chamber of each purification tower 11 through each branch pipeline, and each branch pipeline is provided with a valve III9 for controlling the switch of the branch pipeline, a flowmeter I10 for measuring the flow of the branch pipeline, and a blower 18 for sucking the mixed gas of ammonia and air into the purification tower 11; a nitrogen oxide analyzer 12 for real-time monitoring of the concentration of nitrogen oxides is provided inside the purification tower 11, and the purification tower 11 is connected with the chimney 3 through a flue.

[0023] like Figure 2 As shown, the output end of the nitrogen oxide analyzer 12 is connected to the central control system 15, so that the content of nitrogen oxides is monitored in real time. In addition, the input end of the central control system 15 is also connected to the flow meter Ⅰ10, the flow meter Ⅱ13 and the flow meter Ⅲ14, and the output end of the central control system 15 is connected to the PLC controller 16. The output end of the PLC controller 16 is connected to the dilution fan 1, the valve Ⅰ2, the water pump 5, the valve Ⅱ6, the liquid ammonia evaporator 6, the mixer 8, the valve Ⅲ9 and the blower 18 to control the start and stop.

[0024] like Figure 3 An air inlet chamber 19 and an air outlet chamber 20 which are separated and not connected are arranged in the middle position inside the purification tower 11 shown. Two material chambers which are connected to the air inlet chamber 19 and the air outlet chamber 20 are arranged on both sides of the air inlet chamber 19 and the air outlet chamber 20. Two transition air chambers 21 which are connected to the material chamber are arranged on both sides of the material chamber. An ammonia spraying grid plate 22 is arranged in the middle position of the transition air chamber 21. The mixture of ammonia and air enters the two transition air chambers 21 respectively through each branch pipeline. After the flue gas generated by the sintering machine head enters the material chamber through the air inlet chamber 19, the mixture of ammonia and air diffused from the transition air chamber 21 is more fully mixed under the action of the ammonia spraying grid plate 22, thereby further improving the utilization rate of ammonia water, generating nitrogen and water vapor, and achieving the purpose of denitrification. The generated nitrogen, water vapor and flue gas after denitrification are discharged to the chimney 3 through the flue connected to the air outlet chamber 20 and then discharged into the atmosphere.

[0025] When the system is working, each nitrogen oxide analyzer 12 collects the nitrogen oxide content inside the air inlet chamber 19 of each purification tower 11 and transmits it to the central control system 15. The central control system 15 calculates the amount of ammonia required by the entire system and each purification tower 11, converts it into ammonia water flow, and opens the water pump 5 and valve II6 through the PLC controller 16 to allow the ammonia water to flow into the liquid ammonia evaporator 13. At the same time, the liquid ammonia evaporator 13 is opened to allow the ammonia water to evaporate into ammonia gas and transport it to the mixer 8. At this time, the flow meter II7 monitors the flow of ammonia water in real time and transmits the data to the central control system 15; at the same time, the central control system 15 also The PLC controller 16 opens the dilution fan 1 and valve Ⅰ2 to allow air to flow into the mixer 8 at a fixed flow rate to mix with ammonia. The evenly mixed ammonia-air mixture enters the main pipeline. At the same time, the flow meter Ⅲ monitors the flow of the ammonia-air mixture in real time and transmits the data to the central control system 15; the central control system 15 calculates the opening of the valve Ⅲ9 in each branch according to the amount of ammonia required by each purification tower 11, opens the valve Ⅲ9 to its opening through the PLC controller 16, and turns on the blower 18 to allow the ammonia-air mixture to enter each purification tower 11 to react with nitrogen oxides to generate nitrogen and water, thereby reducing the emission of nitrogen oxides. In addition, the central control system 15 adjusts the corresponding valve opening at any time according to the flow data transmitted in real time by each flow meter, realizes the precise control of ammonia, and achieves the purpose of reducing the emission content of nitrogen oxides while saving ammonia water.

[0026] The output end of the PLC controller 16 is also connected to an alarm 17, which will sound an alarm immediately when a system failure occurs, ensuring that relevant personnel can conduct timely maintenance.

Claims

1. A denitrification intelligent precision ammonia spraying system, comprising a plurality of purification towers (11) and an ammonia branch and an air branch connected in parallel and intersecting in a main pipeline and then connected to each purification tower (11) through branch pipelines, characterized in that: The purification tower (11) is provided with a nitrogen oxide analyzer (12) for measuring the nitrogen oxide concentration in the purification tower; the air branch is provided with a dilution fan (1) and a valve I (2); the ammonia branch is provided with a liquid ammonia tank (4), a water pump (5), a valve II (6), a flow meter II (7) and a liquid ammonia evaporator (13) in sequence; the main pipe is provided with a mixer (8) and a flow meter III (14); each branch pipe is provided with a valve III (9), a flow meter I (10) and a blower (18); The nitrogen oxide analyzer (12), flow meter I (10), flow meter II (7) and flow meter III (14) are connected to a central control system (15); an output end of the central control system is connected to a PLC controller (16); an output end of the PLC controller (16) is connected to a dilution fan (1), a valve I (2), a water pump (5), a valve II (6), a liquid ammonia evaporator (13), a mixer (8), a valve III (9) and a blower (18).

2. According to claim 1, a denitrification intelligent precision ammonia spraying system is characterized by: An air inlet chamber (19) and an air outlet chamber (20) which are separated and not connected are arranged in the middle of the purification tower (11), and the air outlet chamber (20) is connected to the chimney (3) via a flue; two material chambers which are connected to the air inlet chamber (19) and the air outlet chamber (20) are arranged outside the air inlet chamber (19) and the air outlet chamber (20); two transition air chambers (21) which are connected to the material chambers are arranged outside the material chambers, and each branch pipeline is connected to the transition air chamber (21).

3. According to claim 2, a denitrification intelligent precision ammonia injection system is characterized by: An ammonia spraying grid plate (22) is arranged in the middle of the transition air chamber (21) to fully mix the mixed gas of ammonia and air with the nitrogen oxides.

4. The intelligent precise ammonia spraying system for denitrification according to claim 1 is characterized in that: The output end of the PLC controller (5) is also connected to an alarm (17).

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