NOX pressurization treatment device and method

Abstract

The invention relates to the technical field of waste gas treatment, and provides an NOX pressurization treatment device and method. An acid tail gas cooler is used for cooling nitric smoke tail gas; the acidic tail gas buffer tank is used for buffering nitrate gas discharged by the acidic tail gas cooler; the nitrate gas compressor unit is used for pressurizing the nitrate gas; the gas-water separator is used for carrying out gas-water separation on the nitrate gas after being pressurized by the nitrate gas compressor unit; the absorption tower is used for washing the flue gas discharged by the gas-water separator; the soft water transfer tank is used for introducing process water into the top of the absorption tower; nitrate tail gas enters from the bottom of the tower, process water passing through the soft water transfer tank enters from the top of the tower under pumping of the metering pump, NOx in the nitrate tail gas can make full contact with water and air to generate 20% dilute nitric acid, compared with the prior art, the process water in the soft water transfer tank is fully utilized, the resource utilization rate is increased, and the production cost is reduced. The concentration of the generated dilute nitric acid is lower, and the problem that the concentration of the generated dilute nitric acid is higher in the prior art is solved.

Description

Technical Field

[0001] The present invention relates to the technical field of waste gas treatment, and in particular to a NOx pressurized treatment device and method. Background Art

[0002] NOX (nitrogen oxides) pressure treatment is usually a technical means to reduce nitrogen oxide emissions. It is mainly to reduce the nitrogen oxide content in the atmosphere and reduce its harm to the environment and human health. Nitrogen oxides are one of the main pollutants in the atmosphere, which will form acid rain, chemical smog, etc., and have adverse effects on the ecosystem and human respiratory system. By increasing the pressure, NOX is compressed in a specific container or equipment, thereby changing its physical state, which is convenient for subsequent treatment or storage. NOX pressure treatment is mainly used in industrial production, such as large emission sources such as thermal power plants, steel mills, and chemical plants. These companies usually install special NOX treatment equipment, which may include pressure treatment links to ensure that their emissions meet environmental standards.

[0003] Usually, the nitrogen oxide pressurized absorption device is composed of a liquid ring compressor unit and a nitrogen oxide absorption tower. The absorption water is pressurized to above 0.7mPa by an auxiliary plug pump, and is added to the last tower plate from the top of the nitrogen oxide absorption tower. The absorption water is manually adjusted from the last tower plate from top to bottom to absorb and react with the nitrogen oxide gas from the bottom of the nitrogen oxide absorption tower. After the nitrogen oxide gas is absorbed by water, the tail gas reaches below 240mg / m3 (in terms of nitrogen dioxide) and is discharged into the atmosphere through the top of the tower; dilute nitric acid with a concentration of 25%-35% is obtained at the bottom of the tower; the dilute nitric acid with a concentration of 25%-35% enters the liquid ring compressor unit for circulation to increase the concentration to 45%-50%, and the dilute nitric acid with a concentration of 45%-50% is used as the circulating working fluid of the liquid ring compressor unit. The liquid ring compressor unit controls the liquid level through the gas-liquid separator outlet regulating valve, and the dilute nitric acid with a concentration of 45%-50% exceeding the liquid level is discharged from the nitrogen oxide absorption system through the regulating valve; at the same time, the raw nitrogen oxide gas to be treated works through the nitrogen oxide compressor unit, and the pressure is increased from normal pressure to above 0.65mPa, and the concentration of the finished dilute nitric acid is manually adjusted.

[0004] In order to realize automatic control, announcement number CN111644019A discloses a production method of a fully automatic pressurized absorption process of nitric oxide gas. The fully automatic pressurized absorption device system of nitric oxide gas used therein comprises: a tower top pressure transmitter of an absorption water regulating valve, a tower top pressure transmitter of an absorption water reflux valve, a tower top pressure transmitter of a tower bottom liquid level regulating valve, a tower top pressure transmitter of an exhaust gas regulating valve, and a tower top pressure transmitter of a separator gas phase outlet regulating valve. The production method of the fully automatic pressurized absorption process of nitric oxide gas can realize one-key start of the device, and can automatically operate according to the set parameters without manual intervention. The liquid level of the circulating cavity of the liquid ring compressor separator is constant, and the liquid ring of the compressor is kept constant. DCS fully automatic control is adopted, and no daily on-site operators are required. The concentration of dilute nitric acid can be stably controlled, and the exhaust gas concentration can be stably controlled to meet the standard.

[0005] However, the above process still has the following problems: the nitrogen oxide gas absorption water used in the absorption tower of the above process comes from the tap water of the absorption tank. After the nitrogen oxide gas is absorbed by water, the tail gas is discharged into the atmosphere through the top of the tower after meeting the standards, and dilute nitric acid with a concentration of 25%-35% is obtained at the bottom of the tower. Relatively speaking, the concentration of dilute nitric acid generated by this process is relatively high. In addition, the cooling equipment used in the compressor unit in this process is a dilute nitric acid circulation condenser with a self-cooling cycle. Relatively speaking, the cooling effect on the dilute nitric acid in the compressor unit is average, so the energy consumption required for cooling is relatively large. Summary of the invention

[0006] The present invention provides a NOx pressurized treatment device and method, which solves the problems in the prior art that the concentration of the generated dilute nitric acid is high and the cooling effect on the dilute nitric acid in the compressor unit is insufficient.

[0007] The technical solution of the present invention is as follows: A NOx pressurized treatment device, comprising: Acid exhaust gas cooler, used to cool the smoke exhaust gas; Acid tail gas buffer tank, used to buffer the nitrate smoke discharged from the acid tail gas cooler; Smoke compressor unit, used to pressurize smoke gas; Gas-water separator, used to separate gas and water from smoke after it is pressurized by the smoke compressor unit; Absorption tower, used to wash the flue gas discharged from the gas-water separator; Soft water transfer tank, used to introduce process water to the top of the absorption tower; The heat exchanger is used to cool the liquid discharged from the gas-water separator as the working fluid of the smoke compressor unit.

[0008] Preferably, a breathing valve is provided on the connecting pipeline between the acidic tail gas cooler and the acidic tail gas buffer tank.

[0009] Preferably, the top of the absorption tower is externally connected to a pneumatic regulating valve, a muffler and an exhaust pipe.

[0010] Preferably, a metering pump is provided on the pipeline for inputting process water into the absorption tower.

[0011] Preferably, a discharge regulating valve is provided on the discharge pipeline of the gas-water separator.

[0012] Preferably, the smoke compression unit adopts a liquid ring compressor.

[0013] Based on the NOx pressurized treatment device proposed in the above scheme, the present invention also proposes a NOx pressurized treatment method, wherein the nitrate smoke exhaust gas first passes through an acidic exhaust gas cooler, then passes through an acidic exhaust gas buffer tank and then enters a nitrate smoke compressor unit, and the nitrate smoke compressor unit pressurizes the nitrate smoke gas and passes through a gas-water separator before entering an absorption tower, and low-temperature refrigerated circulating water is introduced into the absorption tower; In the absorption tower, the smoke exhaust from the gas-water separator enters from the bottom of the tower, and the process water from the soft water transfer tank enters from the top of the tower. The NOx in the smoke is fully contacted with water and air to generate dilute nitric acid. After the NOx content in the remaining gas at the top of the tower is reduced, it is discharged from the top of the tower. 20% dilute nitric acid generated at the bottom of the absorption tower enters the smoke compression unit as the working fluid. The smoke gas and the working fluid enter the gas-water separator after passing through the smoke compression unit. The dilute nitric acid at the bottom of the gas-water separator is cooled by the heat exchanger and recycled. The smoke gas enters the bottom of the absorption tower after passing through the gas-water separator.

[0014] The beneficial effects of the present invention are: 1. The smoke exhaust gas introduced into the gas-water separator of the present invention enters from the bottom of the tower, and the process water in the soft water transfer tank is pumped by a metering pump and enters from the top of the tower, so that NOx in the smoke gas can be fully contacted with water and air to generate 20% dilute nitric acid. Compared with the prior art, the present invention fully utilizes the process water in the soft water transfer tank, improves resource utilization, and can generate a lower concentration of dilute nitric acid, solving the problem of high concentration of dilute nitric acid generated in the prior art; 2. The present invention passes 20% of the dilute nitric acid generated at the bottom of the absorption tower into the nitrate fume compressor unit as the working fluid of the liquid ring compressor. The nitrate fume and the working fluid enter the gas-water separator after passing through the liquid ring compressor of the nitrate fume compressor unit. The dilute nitric acid at the bottom of the gas-water separator is cooled by a heat exchanger and then recycled. Compared with the prior art, the present invention uses the low-temperature chilled water generated after cooling in the production process of dinitrochlorobenzene as a refrigerant to cool the dilute nitric acid through a heat exchanger, so that the dilute nitric acid is maintained at room temperature, thereby reducing energy consumption, meeting the production requirements of energy conservation and emission reduction, and solving the problem of insufficient cooling effect of the dilute nitric acid in the compressor unit in the prior art. BRIEF DESCRIPTION OF THE DRAWINGS

[0015] The present invention will be further described in detail below in conjunction with the accompanying drawings and specific embodiments.

[0016] Figure 1 A schematic diagram of a process for treating nitr smoke tail gas by a NOX pressurized treatment device proposed in the present invention; In the figure: 11. Acidic tail gas cooler; 12. Acidic tail gas buffer tank; 13. Gun smoke compression unit; 14. Gas-water separator; 15. Absorption tower; 16. Soft water transfer tank; 17. Heat exchanger. DETAILED DESCRIPTION

[0017] The following will be combined with the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0018] See also Figure 1 The present invention provides a technical solution: a NOx pressurized treatment device, comprising an acidic tail gas cooler 11, an acidic tail gas buffer tank 12, a nitrate smoke compressor unit 13, a gas-water separator 14, an absorption tower 15, a soft water transfer tank 16, and a heat exchanger 17, wherein the acidic tail gas cooler 11 is used to cool the nitrate smoke tail gas; the acidic tail gas buffer tank 12 is used to cache the nitrate smoke gas discharged from the acidic tail gas cooler 11; the nitrate smoke compressor unit 13 is used to pressurize the nitrate smoke gas; the gas-water separator 14 is used to separate the nitrate smoke gas from gas and water after pressurizing the nitrate smoke compressor unit 13; the absorption tower 15 is used to wash the smoke discharged from the gas-water separator 14; the soft water transfer tank 16 is used to introduce process water to the top of the absorption tower 15; and the heat exchanger 17 is used to cool the liquid discharged from the gas-water separator 14 as the working fluid of the nitrate smoke compressor unit 13.

[0019] In a preferred embodiment, a breathing valve is provided on the connecting pipeline between the acidic tail gas cooler 11 and the acidic tail gas buffer tank 12 to keep the pressure in the connecting pipeline between the acidic tail gas cooler 11 and the acidic tail gas buffer tank 12 constant.

[0020] In a preferred embodiment, the top of the absorption tower 15 is connected to a pneumatic regulating valve, a muffler and an exhaust pipe. When the NOx content in the gas at the top of the absorption tower 15 reaches below 240ppm, the gas is discharged from the top of the tower through the pneumatic regulating valve, the muffler and the 30m exhaust pipe. The pneumatic regulating valve is used to control the air pressure at the top of the tower to ensure the pressure inside the tower.

[0021] In a preferred embodiment, a metering pump is provided on the pipeline for inputting process water into the absorption tower 15 , so as to pump the process water into the absorption tower 15 in a quantitative manner.

[0022] In a preferred embodiment, a discharge regulating valve is provided on the discharge pipeline of the gas-water separator 14, and the liquid level in the gas-water separator 14 is automatically controlled by the discharge regulating valve to discharge the dilute nitric acid (20%) into the dilute nitric acid tank.

[0023] In a preferred embodiment, the nitrate fume compression unit 13 adopts a liquid ring compressor, and 20% dilute nitric acid is generated at the bottom of the absorption tower 15, which enters the nitrate fume compression unit 13 as the working fluid of the liquid ring compressor. The nitrate fume and the working fluid enter the gas-water separator 14 after passing through the liquid ring compressor. The dilute nitric acid at the bottom of the gas-water separator 14 is cooled by the heat exchanger 17 and then recycled. The nitrate fume gas enters the bottom of the water absorption tower 15 after passing through the gas-water separator 14.

[0024] Based on the above embodiment, the present invention also proposes a NOx pressurized treatment method, wherein the smoke exhaust gas first passes through an acidic exhaust gas cooler 11, and the organic matter in the lower layer of the acidic exhaust gas cooler 11 is recovered to a primary stratification tank (not shown in the figure), and then passes through an acidic exhaust gas buffer tank 12 and enters a smoke compressor unit 13, and the smoke compressor unit 13 pressurizes the smoke gas and passes through a gas-water separator 14 and enters an absorption tower 15, and low-temperature refrigerated circulating water is introduced into the absorption tower 15; In the absorption tower 15, the smoke exhaust gas introduced from the gas-water separator 14 enters from the bottom of the tower, and the process water from the soft water transfer tank 16 enters from the top of the tower by the pumping of the metering pump. The NOx in the smoke gas fully contacts with water and air to generate dilute nitric acid. After the NOx content in the remaining gas at the top of the tower is reduced, it is discharged from the top of the tower; 20% dilute nitric acid generated at the bottom of the absorption tower 15 enters the smoke compressor unit 13 as the working fluid of the liquid ring compressor. The smoke gas and the working fluid enter the gas-water separator 14 after passing through the liquid ring compressor of the smoke compressor unit 13. The dilute nitric acid at the bottom of the gas-water separator 14 is cooled by the heat exchanger 17 and then recycled. The smoke gas enters the bottom of the absorption tower 15 after passing through the gas-water separator 14. The liquid level in the gas-water separator 14 is automatically controlled by the discharge regulating valve, and the dilute nitric acid (20%) is discharged to the dilute nitric acid tank (not shown in the figure). Low-temperature chilled water from the public works is used as a refrigerant to cool the dilute nitric acid through the heat exchanger 17, so that the dilute nitric acid is maintained at room temperature, and the produced dilute nitric acid can be sold externally.

[0025] Since the top of the absorption tower 15 is connected to a pneumatic regulating valve, a muffler and an exhaust pipe, the NOx in the smoke in the absorption tower 15 is fully in contact with water and air to generate dilute nitric acid, and the NO in the remaining gas at the top of the tower X When the content reaches below 240ppm, it is discharged from the top of the tower through a pneumatic regulating valve and a silencer and then through a 30m exhaust pipe. The pneumatic regulating valve controls the air pressure at the top of the tower to ensure the pressure inside the tower.

[0026] It should be noted that the sources of the gunpowder exhaust gas in this embodiment are the concentrated sulfuric acid tank, the first and second level vacuum buffer tanks, the first and second level stratification tanks, the first and second level wastewater tanks, the mononitro mixed acid high-level tank, the dinitro mixed acid high-level tank, the waste acid high-level tank, the emergency tank, the mononitro nitre oil separation tank, the dinitro nitre oil separation tank, the water washing kettle, the water washing separation tank, the water washing wastewater tank, the alkali washing kettle, the alkali washing separation tank, the alkali washing wastewater tank, the extraction kettle, the extraction separation tank, the mononitro and dinitro mixed acid tank, the mononitro and dinitro waste acid tank, the concentrated sulfuric acid transfer tank, the neutralization kettle, the mononitrochlorobenzene tank, the 20% dilute nitric acid tank, the concentrated nitric acid tank and the acid chlorobenzene tank, etc.

[0027] The above are only preferred embodiments of the present invention and are not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc. made within the spirit and principles of the present invention should be included in the protection scope of the present invention.

Claims

1. A NOx pressurized treatment device, characterized in that: include: Acidic tail gas cooler (11), used for cooling the smoke tail gas; An acid tail gas buffer tank (12) is used to buffer the nitrate smoke discharged from the acid tail gas cooler (11); A smoke compressor unit (13) is used to pressurize the smoke gas; A gas-water separator (14) is used to separate gas and water from the fumes after they are pressurized by the fumes compressor unit (13); An absorption tower (15) for washing the flue gas discharged from the gas-water separator (14); A soft water transfer tank (16) is used to introduce process water into the top of the absorption tower (15); The heat exchanger (17) is used to cool the liquid discharged from the gas-water separator (14) as a working fluid for the smoke compressor unit (13).

2. A NOx pressurized treatment device according to claim 1, characterized in that: A breathing valve is provided on the connecting pipeline between the acidic tail gas cooler (11) and the acidic tail gas buffer tank (12).

3. A NOx pressurized treatment device according to claim 1, characterized in that: The top of the absorption tower (15) is externally connected to a pneumatic regulating valve, a muffler and an exhaust pipe.

4. A NOx pressurized treatment device according to claim 1, characterized in that: A metering pump is provided on the pipeline for inputting process water into the absorption tower (15).

5. A NOx pressurized treatment device according to claim 1, characterized in that: The gas-water separator (14) is provided with a discharge regulating valve on its discharge pipeline.

6. A NOx pressurized treatment device according to claim 1, characterized in that: The smoke compressor unit (13) adopts a liquid ring compressor.

7. A NOx pressurized treatment method, according to a NOx pressurized treatment device according to claim 1, characterized in that: The smoke exhaust gas first passes through an acid exhaust gas cooler (11), then passes through an acid exhaust gas buffer tank (12), and then enters a smoke compressor unit (13). The smoke compressor unit (13) pressurizes the smoke exhaust gas and then passes through a gas-water separator (14) and then enters an absorption tower (15). Low-temperature refrigerated circulating water is introduced into the absorption tower (15); In the absorption tower (15), the nitrate smoke exhaust gas introduced from the gas-water separator (14) enters from the bottom of the tower, and the process water from the soft water transfer tank (16) enters from the top of the tower. The NOx in the nitrate smoke gas fully contacts with water and air to generate dilute nitric acid. After the NOx content in the gas remaining at the top of the tower is reduced, it is discharged from the top of the tower. 20% dilute nitric acid generated at the bottom of the absorption tower (15) enters the nitrate fume compression unit (13) as a working fluid. The nitrate fume gas and the working fluid enter the gas-water separator (14) after passing through the nitrate fume compression unit (13). The dilute nitric acid at the bottom of the gas-water separator (14) is cooled by the heat exchanger (17) and then recycled. The nitrate fume gas enters the bottom of the absorption tower (15) after passing through the gas-water separator (14).

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