Nitrogen oxide tail gas pretreatment device

Abstract

The utility model provides a nitrogen oxide tail gas pretreatment device. The nitrogen oxide tail gas pretreatment device comprises a condenser, a circulating pump, a cooling water flow regulating valve and a recycled nitric acid flow regulating valve, an air inlet in the upper part of the condenser is connected with an exhaust pipe of the reactor, a discharge pipe at the bottom of the condenser is connected to an inlet of the circulating pump, and a thermometer is mounted on the discharge pipe; a cooling water outlet pipe is arranged at the upper end of one side of the condenser and a cooling water inlet pipe is arranged at the lower end; a liquid level meter is mounted at the middle lower part of the other side of the condenser; a discharge pipe II is arranged above the liquid level meter; a first circulating pump outlet pipe and a second circulating pump outlet pipe are respectively arranged at an outlet of the circulating pump, the first circulating pump outlet pipe is connected to a top feeding hole of the condenser, and the second circulating pump outlet pipe is connected to the nitric acid recovery tank. The nitrogen oxide tail gas treatment device can be used for treating nitrogen oxide tail gas to reach the pressure and temperature level required by a multi-stage absorption process and simultaneously recovering nitric acid and part of organic matters without secondary pollution. And the economic benefit is high.

Description

TECHNICAL FIELD

[0001] The utility model relates to the chemical industry waste gas treatment field in environmental protection, specifically relates to a nitrogen oxide tail gas pretreatment device. BACKGROUND

[0002] In the process of producing chemical synthetic medicine, nitric acid is often used as oxidant to carry out oxidation reaction, and a large amount of nitrogen oxide gas is generated in the reaction process and needs to be treated, since the gas is directly discharged from the reactor, often contains low-boiling-point reactants or solvents, and has the characteristics of high temperature (≥200 DEG C) and high pressure (≥2MPa), and the existing multistage countercurrent absorption tower can only treat 0.16~0.20MPa, temperature 60 DEG C nitrogen oxide gas, therefore, the nitrogen oxide waste gas must be pretreated before entering the multistage countercurrent absorption tower for resource absorption treatment and recovering nitric acid. SUMMARY

[0003] In order to solve the above problems, the application discloses a nitrogen oxide tail gas pretreatment production device, which is suitable for the pretreatment of nitrogen oxide tail gas discharged from a reaction kettle, and can treat the nitrogen oxide tail gas to the pressure and temperature levels required by the multistage countercurrent absorption process, while recovering nitric acid and part of organic matter. The device operates automatically without secondary pollution, and has high economic benefits.

[0004] A nitrogen oxide tail gas pretreatment device, comprising a condenser, a circulating pump, a cooling water flow regulating valve and a recovered nitric acid flow regulating valve; the upper gas inlet of the condenser is connected with the exhaust pipe of the reactor, the bottom discharge pipe of the condenser is connected to the inlet of the circulating pump, and a thermometer is installed on the discharge pipe; the upper end of one side of the condenser is provided with a cooling water outlet pipe, and the lower end is provided with a cooling water inlet pipe; a liquid level meter is installed on the middle and lower part of the other side of the condenser, and a discharge pipe two is arranged above the liquid level meter; the outlet of the circulating pump is respectively provided with a circulating pump first outlet pipe and a circulating pump second outlet pipe, wherein the circulating pump first outlet pipe is connected to the top feed inlet of the condenser, and the circulating pump second outlet pipe is connected to the nitric acid recovery tank.

[0005] Further, a pressure regulating valve is installed on the exhaust pipe.

[0006] Further, the cooling water outlet pipe is provided with a cooling water flow regulating valve, and the opening degree of the cooling water flow regulating valve is controlled by the thermometer on the bottom discharge pipe of the condenser.

[0007] Further, the circulating pump second outlet pipe is provided with a recovered nitric acid flow regulating valve, and the opening degree of the recovered nitric acid flow regulating valve is controlled by the liquid level meter on the condenser.

[0008] Further, a first check valve is installed on the exhaust pipe to prevent the cooling liquid from flowing back into the reactor under abnormal conditions.

[0009] Further, a second one-way valve is installed on the first outlet pipe of the circulating pump to prevent nitrogen oxide gas from entering the nitric acid recovery tank in abnormal conditions.

[0010] The working principle of the utility model is:

[0011] 1. First, set the control parameter of the pressure regulating valve of the device to 0.19MPa, then inject industrial water into the condenser to 50% of the liquid level meter, and start the circulating pump to realize stable circulation of the circulating water between the condenser and the circulating pump.

[0012] 2. Open the inlet and outlet of the condenser, and set the temperature at the bottom of the condenser to 65℃. After the system is stable, the nitrogen oxide gas discharged from the reaction kettle is cooled to about 65℃ in the condenser, and the water vapor and organic matter with a high boiling point are cooled and then enter the absorption liquid, and the nitrogen oxide gas is discharged from the outlet pipe at the lower part of the condenser and sent to the nitrogen oxide absorption device.

[0013] 3. In this process, the system pressure should be stabilized at 0.18~2.0MPa; the circulating water temperature is stabilized at 60~70℃, and after receiving the nitrogen oxide gas, the liquid level in the condenser gradually rises, when the liquid level rises to 60%, the circulating pump second outlet pipe of the circulating pump is opened to discharge the circulating liquid, and the flow regulating valve and the condenser liquid level are interlocked, and the liquid level control parameter is set to 50%. When the system pressure, circulating liquid temperature and condenser liquid level are stable at the process control target, the whole device enters stable operation.

[0014] The utility model has the advantages of:

[0015] It is suitable for pretreatment of nitrogen oxide tail gas discharged from the reaction kettle, and the device can treat the nitrogen oxide tail gas to the pressure and temperature level required by the multi-stage absorption process, and recover nitric acid and part of the organic matter BRIEF DESCRIPTION OF DRAWINGS

[0016] Figure 1 The device structure diagram of the utility model.

[0017] LIST OF REFERENCE NUMERALS:

[0018] 1-pressure regulating valve; 2-cooling water flow regulating valve; 3-condenser; 4-circulating pump; 5-recovery nitric acid flow regulating valve; 6-exhaust pipe; 7-outlet pipe; 8-thermometer; 9-cooling water outlet pipe; 10-cooling water inlet pipe; 11-liquid level meter; 12-outlet pipe two; 13-circulating pump first outlet pipe; 14-circulating pump second outlet pipe; 15-first one-way valve; 16-second one-way valve. DETAILED DESCRIPTION

[0019] The present invention will be further described below with reference to the accompanying drawings and specific embodiments. It should be understood that the following specific embodiments are intended only to illustrate the present invention and are not intended to limit the scope of the present invention. It should be noted that the terms "front," "rear," "left," "right," "up," and "down" used in the following description refer to directions in the accompanying drawings, and the terms "inward" and "outward" refer to directions toward or away from the geometric center of a particular component, respectively.

[0020] like Figure 1 As shown, a nitrogen oxide tail gas pretreatment device of this embodiment includes a condenser 3, a circulation pump 4, a cooling water flow regulating valve 2 and a nitric acid recovery flow regulating valve 5; the upper air inlet of the condenser 3 is connected to the exhaust pipe 6 of the reactor, and the exhaust pipe 6 is installed with a pressure regulating valve 1 and a first one-way valve 15.

[0021] The bottom discharge pipe 7 of the condenser 3 is connected to the inlet of the circulation pump 4, and a thermometer 8 is installed on the discharge pipe 7; a cooling water outlet pipe 9 is provided at the upper end of one side of the condenser 3 and a cooling water inlet pipe 10 is provided at the lower end; a cooling water flow regulating valve 2 is installed on the cooling water outlet pipe 9, and the opening of the cooling water flow regulating valve 2 is controlled by the thermometer 8 on the bottom discharge pipe 7 of the condenser 3.

[0022] A liquid level gauge 11 is installed in the middle and lower part of the other side of the condenser 3, and a discharge pipe 2 12 is provided above the liquid level gauge 11; the outlet of the circulating pump 4 is respectively provided with a first circulating pump outlet pipe 13 and a second circulating pump outlet pipe 14, wherein the first circulating pump outlet pipe 13 is connected to the top feed port of the condenser 3, and a second one-way valve 16 is installed on the first circulating pump outlet pipe 13.

[0023] The second outlet pipe 14 of the circulating pump is connected to the nitric acid recovery tank; the second outlet pipe 14 of the circulating pump is equipped with a nitric acid recovery flow regulating valve 5, and the opening of the nitric acid recovery flow regulating valve 5 is controlled by the liquid level gauge 11 on the condenser 3.

[0024] Application of this embodiment:

[0025] Fill the condenser with water to about 60% of the liquid level gauge, start the circulating pump, at this time the liquid level should be between 30~50%, open the inlet and outlet water of the condenser, and set the temperature control value at 65℃, control the cooling water flow with the regulating valve, after the system runs stably, confirm that the downstream nitrogen oxide absorption device can receive the nitrogen oxide tail gas, then set the pressure control loop at the position of P+0.02MPa of the nitrogen oxide absorption device pressure (usually 0.2MPa), realize the automatic control of the system pressure, and inform the upstream reactor to slowly discharge the tail gas. The discharge temperature of the tail gas is 150℃, and the discharge pressure is 0~2.0MPa, with the entry of the nitrogen oxide tail gas, the circulating liquid temperature of the condenser starts to rise, and the condenser liquid level gradually rises, open the liquid level regulating valve and set the control loop at 50% to realize the automatic control of the condenser liquid level. Thus realize the stable and automatic operation of the device. The nitrogen oxide gas sent to the nitrogen oxide absorption device has a temperature of 60~70℃, and the recovered nitric acid collected has a concentration of 15~20% and a temperature of 60~70℃.

[0026] The technical means disclosed in the technical scheme of the present application is not limited to the technical means disclosed in the above-mentioned embodiments, but also includes technical schemes composed of any combination of the above technical features.

Claims

1. A nitrogen oxide tail gas pre-treatment device, characterized by: It comprises a condenser (3), a circulating pump (4), a cooling water flow regulating valve (2) and a recovered nitric acid flow regulating valve (5); the upper air inlet of the condenser (3) is connected with the exhaust pipe (6) of the reactor, the discharge pipe (7) at the bottom of the condenser (3) is connected with the inlet of the circulating pump (4), and a thermometer (8) is installed on the discharge pipe (7); the upper end of one side of the condenser (3) is provided with a cooling water outlet pipe (9) and the lower end is provided with a cooling water inlet pipe (10); a liquid level meter (11) is installed on the middle lower part of the other side of the condenser (3), and a discharge pipe two (12) is arranged above the liquid level meter (11); the outlet of the circulating pump (4) is respectively provided with a circulating pump first outlet pipe (13) and a circulating pump second outlet pipe (14), wherein the circulating pump first outlet pipe (13) is connected with the top inlet of the condenser (3), and the circulating pump second outlet pipe (14) is connected with the nitric acid recovery tank.

2. A device for the pre-treatment of exhaust gases containing nitrogen oxides according to claim 1, characterized in that: A pressure regulating valve (1) is installed on the exhaust pipe (6).

3. A device for the pre-treatment of nitrogen oxide exhaust gases according to claim 1, characterized in that: The cooling water outlet pipe (9) is provided with a cooling water flow regulating valve (2).

4. A device for the pre-treatment of nitrogen oxide exhaust gases according to claim 1, characterized in that: The circulating pump second outlet pipe (14) is provided with a recovered nitric acid flow regulating valve (5).

5. A device for the pre-treatment of nitrogen oxide exhaust gases according to claim 1, characterized in that: A first one-way valve (15) is installed on the exhaust pipe (6).

6. A device for the pre-treatment of nitrogen oxide exhaust gases according to claim 1, characterized in that: A second one-way valve (16) is installed on the circulating pump first outlet pipe (13).

Images