Energy-saving urea dissolving tank tail gas deodorization spraying system

Abstract

The utility model discloses an energy-saving urea dissolving tank tail gas deodorization spraying system which is arranged on a urea dissolving tank and comprises a tail gas pipe, a mixer, a deodorization spraying device and a drainage collecting tank, one end of the tail gas pipe is communicated with the urea dissolving tank, the other end of the tail gas pipe extends into the mixer from bottom to top, the deodorization spraying device is arranged in the mixer, and the drainage collecting tank is arranged in the mixer. The lower end of the mixer is communicated with the drainage collecting tank through a first drainage pipe, and the drainage collecting tank is communicated with the urea dissolving tank through a second drainage pipe. According to the utility model, the ammonia-containing tail gas is introduced into the mixer, ammonia gas is absorbed through a small amount of spraying water, and the ammonia gas is sent into the urea dissolving tank again through the drainage collecting tank for recycling, so that the energy consumption is effectively reduced, and meanwhile, the environmental pollution is reduced.

Description

Technical Field

[0001] The utility model belongs to the technical field of flue gas denitrification, and particularly relates to an energy-saving deodorizing spray system for the tail gas of a urea dissolving tank. Background Art

[0002] The control of NOx is one of the key points in the environmental protection treatment of coal-fired power plants. At present, the selective catalytic reduction flue gas denitrification technology SCR is the most widely used denitrification technology in coal-fired power plants, and the commonly used denitrification reducing agents are liquid ammonia and urea. The urea ammonia production process is to dissolve urea particles and demineralized water in a urea dissolving tank to prepare a urea solution with a specified concentration, pump it to a urea solution storage tank for storage, and then use a urea solution circulation pump to transport it to a urea decomposition system for decomposition to produce ammonia. During the dissolution and preparation of the urea solution, the tail gas generated by the urea dissolving tank carries a small amount of ammonia. If it is directly discharged into the atmosphere, it will cause air pollution. The existing deodorization measure is to use an exhaust fan to introduce the tail gas into a waste water tank through the tail gas pipe of the urea dissolving tank, and the ammonia is absorbed by the water in the waste water tank. However, the exhaust fan required for this deodorization device to discharge the tail gas into the waste water tank has a relatively high energy consumption. Therefore, setting up an energy-saving deodorizing spray system for tail gas deodorization is an effective energy-saving measure for the urea ammonia production process in the technical field of flue gas denitrification. Content of the Utility Model

[0003] Aiming at the deficiencies in the prior art, the purpose of the utility model is to provide an energy-saving deodorizing spray system for the tail gas of a urea dissolving tank.

[0004] The specific technical solutions are as follows:

[0005] An energy-saving deodorizing spray system for the tail gas of a urea dissolving tank is arranged on the urea dissolving tank, and includes a tail gas pipe, a mixer, a deodorizing spray device and a drainage collection tank. One end of the tail gas pipe is communicated with the urea dissolving tank, and the other end extends into the mixer from bottom to top. The deodorizing spray device is arranged in the mixer and is located above the end of the tail gas pipe. The lower end of the mixer is communicated with the drainage collection tank through a first drain pipe, and the drainage collection tank is communicated with the urea dissolving tank through a second drain pipe.

[0006] Further, the deodorizing spray device includes a spray water pipe and spray branch pipes. An electromagnetic valve is arranged on the spray water pipe. The spray water pipe is connected with multiple groups of spray branch pipes. The spray branch pipes extend into the mixer. Multiple nozzles are arranged on the spray branch pipes, and the openings of the nozzles face the direction of the tail gas pipe.

[0007] Further, the mixer is a vertical pipe. A rain shield is arranged at the upper end of the vertical pipe, and the lower end is communicated with the drainage collection tank through a first drain pipe.

[0008] Further, a switch valve is arranged on the second drain pipe.

[0009] Furthermore, the inner diameter of the mixer is 2 to 3 times the inner diameter of the tail pipe.

[0010] Furthermore, the cross-sectional area of ​​the mixer is 2 At least one nozzle is evenly distributed, and the number of nozzles is required to ensure that the spray water sprayed into the mixer from the nozzle can fully cover the cross-sectional area of ​​the mixer as much as possible, thereby reducing the escape of ammonia in the tail gas.

[0011] Furthermore, the height difference between the nozzle of the deodorizing spray device and the exhaust pipe is at least 10-15 times the diameter of the mixer. The height difference requirement from the nozzle to the exhaust pipe ensures that the spray water sprayed from the nozzle into the mixer can be fully mixed with the exhaust gas as much as possible, thereby reducing the outflow of ammonia in the exhaust gas.

[0012] The beneficial effects of the utility model are:

[0013] The utility model introduces ammonia-containing tail gas into a mixer, absorbs ammonia through a small amount of spray water, and re-sends the ammonia through a drainage collection tank to a urea dissolving tank for reuse, thereby effectively reducing energy consumption and environmental pollution. BRIEF DESCRIPTION OF THE DRAWINGS

[0014] Figure 1 It is a schematic diagram of the system structure of the utility model.

[0015] In the figure: 1. urea dissolution tank; 2. tail gas pipe; 3. mixer; 4. drainage collection tank; 5. first drainage pipe; 6. second drainage pipe; 7. spray water pipe; 8. spray branch pipe; 9. solenoid valve; 10. nozzle; 11. rain cover; 12. switch valve. DETAILED DESCRIPTION

[0016] The utility model is further described below in conjunction with the drawings in the specification, but the protection scope of the utility model is not limited thereto.

[0017] like Figure 1As shown in the figure, an energy-saving tail gas deodorization spraying system for a urea dissolution tank is installed on the urea dissolution tank 1, and includes a tail gas pipe 2, a mixer 3, a deodorization spraying device, a drainage collection tank 4, a first drain pipe 5 and a second drain pipe 6. The deodorization spraying device includes a spraying water pipe 7 and spraying branch pipes 8. One end of the tail gas pipe 2 is connected to the urea dissolution tank 1, and the other end extends into the mixer 3 from bottom to top. The mixer 3 is a vertical pipe. A rain shield 11 is provided at the upper end of the vertical pipe, and the lower end is connected to the drainage collection tank 4 through the first drain pipe 5. The drainage collection tank 4 is connected to the urea dissolution tank 1 through the second drain pipe 6. A switch valve 12 is provided on the second drain pipe 6. An electromagnetic valve 9 is provided on the spraying water pipe 7. The spraying water pipe 7 is connected to multiple spraying branch pipes 8. The spraying branch pipes 8 extend into the mixer 3 and are located above the end of the tail gas pipe 2. Multiple nozzles 10 are provided on the spraying branch pipes 8. At least one nozzle 10 is evenly distributed per 0.1 m of the cross-sectional area of the mixer 3. The opening of the nozzle 10 faces the direction of the tail gas pipe 2. The inner diameter of the mixer 3 is 2-3 times the inner diameter of the tail gas pipe 2. The height difference between the nozzle 10 of the deodorization spraying device and the tail gas pipe 2 is at least 10-15 times the diameter of the mixer 3. 2 For every 0.1 m² of the cross-sectional area of the mixer 3, at least one nozzle 10 is evenly distributed. The opening of the nozzle 10 faces the direction of the tail gas pipe 2. The inner diameter of the mixer 3 is 2-3 times the inner diameter of the tail gas pipe 2. The height difference between the nozzle 10 of the deodorization spraying device and the tail gas pipe 2 is at least 10-15 times the diameter of the mixer 3.

[0018] Before the urea dissolution tank 1 is ready to prepare urea solution, first open the electromagnetic valve 9, and spray the spraying water into the mixer 3 in the reverse direction of the tail gas through the spraying water pipe 7 and the spraying branch pipes 8. When the urea particles are sent to the urea dissolution tank 1 through the urea particle pneumatic conveying pipe, due to the slightly positive pressure brought by the pneumatic conveying process, the gas in the urea particle pneumatic conveying pipeline is discharged through the tail gas pipe 2. After the trace amount of ammonia gas in the tail gas during the urea dissolution process enters the mixer 3, it convectively contacts the spraying water sprayed into the mixer 3, so that the trace amount of ammonia gas in the tail gas is fully absorbed by the spraying water, achieving the purpose of tail gas deodorization. The spraying water that has absorbed ammonia gas enters the drainage collection tank 4. Before preparing the next tank of urea solution, open the switch valve 12, and recycle the drainage to the urea dissolution tank 1 through the second drain pipe 6.

[0019] The flow rate of the tail gas pipe 2 is the flow rate of the compressed air required for the pneumatic conveying of urea particles. The medium flow velocity of the tail gas pipe 2 is selected as 12-15 m / s, and the gas flow velocity in the mixer 3 is selected as 2-3 m / s to ensure that the residence time of the tail gas in the mixer 3 is not less than 5 s, ensuring that the tail gas can fully contact the spraying water.

[0020] The spraying water flow rate is selected according to the liquid-gas ratio of 5-10 L / m³ of the ammonia gas flow rate in the tail gas. 3 The spraying water flow velocity is selected as 2-3 m / s. A reasonable spraying water flow rate ensures that while fully absorbing the trace amount of ammonia gas in the tail gas, the water consumption of the spraying water is saved.

[0021] The volume of the drainage collection tank 4 is selected as 1.2 times the amount of spraying water required to prepare one tank of urea solution.

[0022] The cross-sectional area of the first drain pipe 5 is 2-3 times that of the spray water pipe 7, so that the spray water can be smoothly discharged into the first drain pipe 5 at the bottom of the mixer 3 without liquid accumulation.

Claims

1. An energy-saving tail gas deodorizing spray system for a urea dissolution tank, which is arranged on the urea dissolution tank (1), and is characterized in that, It includes an exhaust pipe (2), a mixer (3), a deodorizing spray device and a drainage collection tank (4). One end of the exhaust pipe (2) is connected to the urea dissolution tank (1), and the other end extends into the mixer (3) from bottom to top. The deodorizing spray device is arranged in the mixer (3) and is located above the end of the exhaust pipe (2). The lower end of the mixer (3) is connected to the drainage collection tank (4) through a first drain pipe (5), and the drainage collection tank (4) is connected to the urea dissolution tank (1) through a second drain pipe (6).

2. The energy-saving urea dissolving tank tail gas deodorization spraying system according to claim 1, characterized in that, The deodorizing spray device includes a spray water pipe (7) and spray branch pipes (8). A solenoid valve (9) is provided on the spray water pipe (7). The spray water pipe (7) is connected to multiple groups of spray branch pipes (8). The spray branch pipes (8) extend into the mixer (3), and multiple nozzles (10) are provided on the spray branch pipes (8). The nozzles (10) are opened in the direction of the exhaust pipe (2).

3. The energy-saving urea dissolution tank tail gas deodorization spray system according to claim 1, characterized in that, The mixer (3) is a vertical pipe. A rain shield (11) is provided at the upper end of the vertical pipe, and the lower end is connected to the drainage collection tank (4) through a first drain pipe (5).

4. An energy-saving tail gas deodorization spraying system for a urea dissolution tank according to claim 1, characterized in that, A switch valve (12) is provided on the second drain pipe (6).

5. An energy-saving urea dissolution tank tail gas deodorization spray system as described in claim 1, characterized in that, The inner diameter of the mixer (3) is 2-3 times the inner diameter of the exhaust pipe (2).

6. The energy-saving urea dissolving tank tail gas deodorization spraying system according to claim 1, characterized in that, The cross-sectional area of the mixer (3) is evenly provided with at least one nozzle (10) per 0.1 m 2 .

7. An energy-saving tail gas deodorization spraying system for a urea dissolving tank according to claim 1, characterized in that, The height difference between the nozzle (10) of the deodorizing spray device and the exhaust pipe (2) is at least 10-15 times the diameter of the mixer (3).

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