Adipic acid reaction device

Abstract

The utility model discloses an adipic acid reaction device which comprises an oxidation unit and a drying unit, a nitrous acid steam pipe for recycling is arranged at the top of a reaction kettle of the oxidation unit, and an air inlet pipe for oxidizing nitrous acid is connected with the nitrous acid steam pipe; a tail gas discharge pipe of the drying unit is connected with a nitrous acid steam pipe, and oxygen in tail gas and nitrous acid steam are mixed to complete nitrous acid oxidation and then are recycled. According to the device, tail gas discharged by the drying unit serves as an oxidizing agent of nitrous acid, pollution of tail gas emission to the environment is reduced, and the energy utilization rate is increased; the dust content of the tail gas subjected to multi-stage filtration and washing is extremely low, so that the product quality of adipic acid and downstream polyester products thereof is improved; the demand quantity of purified air is reduced, and the production cost is reduced; the structure is simple, transformation is convenient, cost is low, and popularization is easy.

Description

Technical Field

[0001] The utility model relates to a production process of adipic acid, in particular to a reaction device for adipic acid. Background Art

[0002] Adipic acid, commonly known as fatty acid, is an important organic dicarboxylic acid widely used in chemical production, organic synthesis, pharmaceuticals, lubricant manufacturing, and other fields, ranking second in production volume among all dicarboxylic acids. Currently, its production process involves oxidizing alcohols and ketones with excess nitric acid over the catalysts of vanadium pentoxide and copper. During the adipic acid production process, large amounts of gases such as NO and NO₂ are generated. To reduce costs and optimize resource utilization, air is introduced into the system to convert NO into NO₂, which then reacts with water to generate more nitric acid for oxidizing alcohols and ketones to produce adipic acid. However, air contains a high amount of dust, which enters the adipic acid production system along with the nitric acid solution, negatively impacting product quality and altering the color of downstream polyester products. To mitigate the effects of airborne dust, multiple stages of filtration are required before the air enters the system, increasing production costs. Furthermore, during the adipic acid production process, the newly generated adipic acid material needs to be cooled, dried, and then collected. Air passes through a pre-filter and a precision filter before entering a dry cooler to remove moisture from the adipic acid material. A cyclone then intercepts adipic acid dust. Air above the cyclone enters a scrubber, where it is sprayed with pure water for absorption and purification before being discharged by an induced draft fan. The exhaust gas from this process undergoes multiple stages of filtration, resulting in minimal dust. Direct discharge would not be a rational use of resources and would be a waste of resources. Utility Model Content

[0003] Purpose of the utility model: The purpose of this utility model is to provide a reaction device for adipic acid in order to improve energy utilization, reduce energy consumption, and improve product quality.

[0004] Technical solution: The adipic acid reaction device described in the utility model includes an oxidation unit and a drying unit. The top of the reactor of the oxidation unit is provided with a nitrous acid steam pipe for recycling and reuse, and the air inlet pipe for oxidizing nitrous acid is connected to the nitrous acid steam pipe; the tail gas discharge pipe of the drying unit is connected to the nitrous acid steam pipe, and the oxygen in the tail gas is mixed with the nitrous acid steam to complete the nitrous acid oxidation and then recycled and reused.

[0005] Furthermore, the exhaust pipe is provided with a flow meter for monitoring the exhaust gas intake, which shares a flow meter with the original air intake pipe and is used to monitor the intake of purified air to ensure sufficient oxygen to react with nitrous acid to oxidize it and then recycle it into the adipic acid oxidation reactor, thereby improving the utilization rate of raw materials.

[0006] Furthermore, the exhaust pipe is provided with an exhaust port for discharging excess exhaust gas. The exhaust gas emission of the drying unit is about 40,000 Nm 3 / h, which is much larger than the air flow rate of 8000-12000Nm required for nitrous acid oxidation 3 / h, the excess exhaust gas is discharged from the exhaust port to prevent the high pressure in the nitrous steam pipe from causing safety hazards.

[0007] Furthermore, the interface between the exhaust pipe and the induced draft fan in the drying unit is 50-100 mm above the ground to ensure the stability of the airflow in the exhaust pipe. Sufficient gas is added based on the pressure in the nitrous acid vapor pipe to complete the oxidation of the nitrous acid. The stability of the airflow in the exhaust pipe affects the amount of gas added. Excessive gas flow can affect the pipe pressure, posing a safety hazard. Excessive gas flow can lead to incomplete nitrous acid oxidation and affect the utilization rate of raw materials.

[0008] Furthermore, the tail gas discharge pipe is made of stainless steel to prevent impurity iron ions from entering the system and affecting the quality of the finished adipic acid.

[0009] Furthermore, the nitrous acid steam pipe is provided with a pressure regulating valve for regulating the pressure in the pipe and a pressure gauge for monitoring the pressure in the pipe. By monitoring and adjusting the pressure in the pipe, appropriate purified air is added to ensure that the nitrous acid is fully oxidized before being fed into the reactor for the production of adipic acid.

[0010] Furthermore, the air intake pipe is provided with a valve for controlling its opening and closing. When the exhaust gas generated by the drying unit is in operation and is sufficient to meet the oxidation demand of nitrous acid, no additional purified air is required, and the air intake pipe is closed to reduce the energy consumption of the production line. When the exhaust gas of the drying unit is insufficient to support the oxidation demand of nitrous acid, the valve is opened to adjust the amount of purified air added to ensure that the nitrous acid is fully oxidized before being put into the reactor for the production of adipic acid.

[0011] Beneficial effects: Compared with the existing technology, the utility model has the following advantages: 1. The exhaust gas discharged by the drying unit is used as an oxidant for nitrous acid, thereby reducing the pollution of the exhaust gas to the environment and improving the energy utilization rate; 2. The dust content of the exhaust gas after multi-stage filtration and washing is extremely low, which improves the product quality of adipic acid and its downstream polyester products; 3. The demand for purified air is reduced, and the production cost is reduced; 4. The structure is simple, the modification is convenient, and the cost is low. BRIEF DESCRIPTION OF THE DRAWINGS

[0012] Figure 1 It is a structural diagram of the present utility model. DETAILED DESCRIPTION

[0013] The technical solution of the present utility model will be further described below with reference to the accompanying drawings.

[0014] like Figure 1 The illustrated adipic acid reaction apparatus comprises an oxidation unit and a drying unit. The oxidation unit includes a reactor 9, with a nitrous acid vapor pipe 16 for recycling and reuse at its top. An air inlet pipe 12 for oxidizing nitrous acid is connected to the nitrous acid vapor pipe 16. The air inlet pipe 12 is equipped with a first prefilter 13, a first precision filter 15, and a valve 14. The drying unit comprises a dry cooler 1, a dust collector 2, a scrubber 3, and an induced draft fan 4. Air passes through a second prefilter 5 and a second precision filter 6 for multi-stage filtration before entering the bottom of the dry cooler 1 to dry and cool the adipic acid material. Adipic acid powder enters the dust collector 2 from a powder delivery pipe at the top of the dry cooler 1. The adipic acid powder is intercepted and collected at the bottom of the dust collector 2. Air mixed with the powder enters the bottom of the scrubber 3 through an exhaust gas delivery pipe. The exhaust gas, after being scrubbed by the scrubber 3, is discharged through an induced draft fan 4 into an exhaust gas discharge pipe 8. The interface between exhaust pipe 8 and induced draft fan 4 is 50 mm above the ground (this height can be set to 50-100 mm while meeting airflow stability and installation requirements). Its diameter is DN=500 and made of 304 stainless steel. Exhaust pipe 8 is equipped with an exhaust flow meter 17 for monitoring the amount of exhaust gas entering and an exhaust outlet 7 for discharging excess exhaust gas. Exhaust pipe 8 is connected to a nitrous acid steam pipe 16. Oxygen in the exhaust gas mixes with the nitrous acid steam to oxidize the nitrous acid for recycling. Nitrous acid steam pipe 16 is equipped with a pressure regulating valve 10 for regulating the pressure within the pipe and a pressure gauge 18 for monitoring the pressure within the pipe.

[0015] When the drying unit is not working, open valve 14, and air in the natural world passes through the first pre-filter 13 and the first precision filter 15 and enters the nitrous acid steam pipe 16. The flow rate is controlled by the flow meter 17, the pressure in the pipe is monitored by the pressure gauge 18, and the pressure in the pipe is regulated by the pressure regulating valve 10, so that the oxygen in the air fully reacts with the nitrous acid to oxidize it into nitric acid, which is then recycled and put back into the adipic acid oxidation reactor 9. When the drying unit is working, the exhaust gas emission is about 40,000 Nm 3 / h is much larger than the air flow rate of 8000-12000Nm required for nitrous acid oxidation 3 / h, no additional purified air is needed, so valve 14 is closed and flow meter 17 monitors the exhaust gas flow rate at 8000-12000Nm 3 / h, the excess tail gas is discharged from the tail gas outlet 7, the pressure in the pipeline is monitored by the pressure gauge 18 through the nitrous acid steam pipe 16, and the pressure in the pipeline is regulated by the pressure regulating valve 10, so that the oxygen in the tail gas fully reacts with the nitrous acid to oxidize it into nitric acid, which is then recycled and fed back into the adipic acid oxidation reactor 9.

Claims

1. A reaction device for adipic acid, comprising an oxidation unit and a drying unit, wherein a nitrous acid steam pipe (16) for recycling is provided on the top of a reactor (9) of the oxidation unit, and an air inlet pipe (12) for oxidizing nitrous acid is connected to the nitrous acid steam pipe (16); characterized in that: The tail gas discharge pipe (8) of the drying unit is connected to the nitrous acid steam pipe (16), and the oxygen in the tail gas is mixed with the nitrous acid steam to complete the nitrous acid oxidation and then recycled for reuse.

2. The reaction device for adipic acid according to claim 1, characterized in that The tail gas discharge pipe (8) is provided with a flow meter (17) for monitoring the amount of tail gas introduced.

3. The reaction device for adipic acid according to claim 2, characterized in that: The exhaust gas discharge pipe (8) is provided with an exhaust gas discharge port (7) for discharging excess exhaust gas.

4. The reaction device for adipic acid according to claim 2, characterized in that: The height of the interface between the exhaust gas discharge pipe (8) and the induced draft fan (4) in the drying unit from the ground is 50-100 mm.

5. The reaction device for adipic acid according to claim 2, characterized in that: The tail gas discharge pipe (8) is made of stainless steel.

6. The reaction device for adipic acid according to claim 1, characterized in that: The nitrous acid steam pipe (16) is provided with a pressure regulating valve (10) for regulating the pressure in the pipe.

7. The reaction device for adipic acid according to claim 6, characterized in that: The nitrous acid steam pipe (16) is provided with a pressure gauge (18) for monitoring the pressure in the pipe.

8. The reaction device for adipic acid according to claim 1, characterized in that: The air intake pipe (12) is provided with a valve (14) for controlling its opening and closing.

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