A device system for treating waste acid and applying to nitro o-xylene nitration

Abstract

The utility model relates to the technical field of chemical device system, and its in order to solve the problem of security risk and resource waste caused by the accumulation of floating medicine in the storage process of waste acid after nitro o-xylene nitration, the utility model provides a kind of device system of waste acid treatment and applied to nitro o-xylene nitration, including waste acid vat, waste acid curing reactor, waste acid heater, denitration tower, sulfuric acid buffer unit, nitration unit and nitrous smoke processing unit;Waste acid vat and waste acid curing reactor circulation intercommunication;The liquid discharge end of waste acid curing reactor is communicated with the feed end of waste acid heater;Waste acid heater and denitration tower intercommunication;The top of denitration tower and nitrous smoke processing unit intercommunication;The bottom of denitration tower and sulfuric acid buffer unit intercommunication;Sulfuric acid buffer unit and nitration unit intercommunication;The device system provided by the utility model can effectively solve the security risk in the storage process of waste acid, and realizes effective use of resources.

Description

Technical Field

[0001] This utility model relates to the field of chemical equipment system technology, and more specifically, to an equipment system for treating waste acid and applying it to the nitration of nitro-o-xylene. Background Technology

[0002] In the nitration process of o-nitroxylene, a large amount of waste sulfuric acid with complex composition is generated. The traditional treatment mode of this waste acid is as follows: the material after the nitration reaction is statically separated, and the waste acid after separating the crude product is transported to the waste acid storage tank for temporary storage.

[0003] However, since the waste acid after nitration is not an inert system, it contains a variety of incompletely separated nitro organic byproducts. These organics are chemically unstable and highly reactive. Therefore, when the waste acid containing unstable organics is transported to a static storage tank, the dissolved organics will continue to undergo slow secondary chemical reactions under room temperature storage conditions. The direct products of these reactions are called "floating agents". The formation process of floating agents is a continuous exothermic process. Therefore, when the floating agents accumulate to a critical amount and the local temperature reaches its auto-ignition point or thermal decomposition temperature, it will uncontrollably cause spontaneous combustion, burning or even explosion.

[0004] Based on the above description, there is an urgent need for a waste acid curing treatment device system that can fundamentally eliminate safety hazards and simultaneously achieve resource recycling. Utility Model Content

[0005] The purpose of this invention is to provide a device system for treating waste acid and applying it to the nitration of o-nitroxylene, aiming to solve the technical problems of safety hazards and resource waste caused by the accumulation of floating chemicals during the storage of waste acid after nitration of o-nitroxylene.

[0006] The embodiments of this utility model are achieved through the following technical solutions: A waste acid treatment system for nitration of o-nitroxylene includes a waste acid tank, a waste acid aging reactor, a waste acid heater, a denitrification tower, a sulfuric acid buffer unit, a nitration unit, and a nitrification fume treatment unit. The waste acid tank is in continuous circulation with the waste acid aging reactor. The discharge end of the waste acid aging reactor is connected to the feed end of the waste acid heater. The waste acid heater is connected to the denitrification tower. The top of the denitrification tower is connected to the nitrification fume treatment unit. The bottom of the denitrification tower is connected to the sulfuric acid buffer unit. The sulfuric acid buffer unit is connected to the nitration unit.

[0007] Preferably, the waste acid maturation reactor is connected to the waste acid tank via a first feed branch pipe; the waste acid maturation reactor is connected to the waste acid heater via a second feed branch pipe; the discharge end of the waste acid maturation reactor is connected to a main feed pipe; the main feed pipe, the first feed branch pipe, and the second feed branch pipe are connected via a three-way valve.

[0008] Preferably, the first conveying branch pipe is equipped with a circulation pump.

[0009] Preferably, the sulfuric acid buffer unit includes a dilute sulfuric acid buffer tank and a concentration tank; the discharge end of the denitrification tower is connected to the dilute sulfuric acid buffer tank; the dilute sulfuric acid buffer tank is connected to the feed end of the concentration tank; and the discharge end of the concentration tank is connected to the nitration unit.

[0010] Preferably, the nitrification treatment unit includes a flue gas condenser, a nitrification absorption tower, and a dilute nitric acid receiving tank; the top of the denitrification tower is connected to the inlet end of the flue gas condenser; the exhaust end of the flue gas condenser is connected to the nitrification absorption tower; and the drain end of the nitrification absorption tower is connected to the dilute nitric acid receiving tank.

[0011] Preferably, the exhaust end of the nitrile smoke absorption tower is connected to a tail gas treatment unit.

[0012] Preferably, the exhaust gas treatment unit includes an exhaust gas absorption tower and a decomposition tower; the feed end of the exhaust gas absorption tower is connected to the exhaust end of the nitrate smoke absorption tower; and the exhaust end of the exhaust gas absorption tower is connected to the decomposition tower.

[0013] Preferably, the tail gas absorption tower is connected to an acid supply tank; the concentration tank is connected to the acid supply tank.

[0014] The technical solution of this utility model embodiment has at least the following advantages and beneficial effects: This invention eliminates the safety hazard of "floating chemicals" accumulation by first pumping waste acid into a waste acid maturation reactor, allowing the unstable organic matter to fully react. Simultaneously, the matured waste acid is heated and concentrated before entering a denitrification tower, where it further absorbs nitrogen oxides and is purified. The resulting purified acid solution is then concentrated to the required concentration and reused in the acid preparation process of the nitration unit. Meanwhile, the nitrate fumes generated during denitrification are recovered and converted into dilute nitric acid, and the residual tail gas is treated to meet emission standards. The entire system forms a closed-loop cycle of waste acid and nitrates, which not only completely solves safety and environmental hazards but also significantly reduces production costs. Attached Figure Description

[0015] Figure 1 This is a schematic diagram of the device system of this utility model; Figure 2 for Figure 1 System schematic diagram of the denitrification unit; Figure 3 for Figure 1 A schematic diagram of the medium-density smoke treatment unit.

[0016] Icons: 1-Waste acid tank, 2-Waste acid maturation reactor, 3-Waste acid heater, 4-Denitrification tower, 5-Sulfuric acid buffer unit, 51-Dilute sulfuric acid buffer tank, 52-Concentration tank, 6-Nitrification unit, 7-Flame treatment unit, 71-Flue gas condenser, 72-Flame absorption tower, 73-Dilute nitric acid receiving tank, 8-Three-way valve, 9-Circulation pump, 10-Tail gas treatment unit, 101-Gas absorption tower, 102-Decomposition tower, 11-Acid supply tank. Detailed Implementation

[0017] The specific implementation method is described below with reference to the accompanying drawings.

[0018] Example 1 Please see Figures 1 to 3 The present invention provides the following technical solution: a device system for treating waste acid and applying it to the nitration of nitro-o-xylene, which is suitable for the treatment and reuse of waste acid after nitration of nitro-o-xylene.

[0019] Specifically, such as Figures 1 to 3 As shown, a waste acid treatment and application device system for the nitration of nitro-o-xylene includes a waste acid tank 1, a waste acid aging reactor 2, a waste acid heater 3, a denitrification tower 4, a sulfuric acid buffer unit 5, a nitration unit 6, and a nitrification fume treatment unit 7. The waste acid tank 1 is in cyclic communication with the waste acid aging reactor 2. The discharge end of the waste acid aging reactor 2 is connected to the feed end of the waste acid heater 3. The waste acid heater 3 is connected to the denitrification tower 4. The top of the denitrification tower 4 is connected to the nitrification fume treatment unit 7. The bottom of the denitrification tower 4 is connected to the sulfuric acid buffer unit 5. The sulfuric acid buffer unit 5 is connected to the nitration unit 6.

[0020] In this embodiment, the waste acid tank 1 is a corrosion-resistant steel tank resistant to strong acids, equipped with a level gauge, temperature sensor and overflow guardrail, etc., to realize real-time monitoring of acid volume and temperature; furthermore, the waste acid maturation reactor 2 is equipped with a stirring paddle and heating coil to maintain the acid at a constant temperature of 30~40℃, so that suspended particles in the acid settle and nitric acid and sulfuric acid are fully mixed, preventing local overheating or scaling during subsequent heating.

[0021] In this embodiment, the waste acid heater 3 adopts indirect steam heating. The waste acid heater 3 is equipped with a temperature control valve and a safety check valve to ensure that the acid is heated uniformly within the range of 120~130℃, avoiding acid decomposition or the generation of corrosive gases due to excessively high local temperatures. After heating, the concentration of the acid increases to about 80% H2SO4, providing a sufficient acidic environment for subsequent denitrification.

[0022] In this embodiment, the heated acid solution is pumped into the bottom of the denitrification tower 4 through an acid-resistant pipeline, utilizing the strong acidity of the acid solution to remove NO from the tower. x (Mainly NO2) is absorbed, while the purified acid solution at the bottom of the tower is passed into the dilute sulfuric acid unit.

[0023] Specifically, such as Figure 1 and Figure 2 As shown, the waste acid maturation reactor 2 is connected to the waste acid tank 1 through the first feed branch pipe; the waste acid maturation reactor 2 is connected to the waste acid heater 3 through the second feed branch pipe; the discharge end of the waste acid maturation reactor 2 is connected to the feed main pipe; the feed main pipe, the first feed branch pipe and the second feed branch pipe are connected through the three-way valve 8.

[0024] Specifically, such as Figure 2 As shown, the first material conveying branch pipe is equipped with a circulating pump 9.

[0025] In this embodiment, the circulating pump 9 is an acid-resistant stainless steel screw pump, which pumps the acid in the waste acid tank 1 to the waste acid maturation reactor 2, and then returns it to the waste acid tank 1 after maturation, forming a closed loop circulation, which ensures the stability of the acid quality and reduces the amount of waste acid discharged.

[0026] Specifically, such as Figure 3 As shown, the sulfuric acid buffer unit 5 includes a dilute sulfuric acid buffer tank 51 and a concentration tank 52; the discharge end of the denitrification tower 4 is connected to the dilute sulfuric acid buffer tank 51; the dilute sulfuric acid buffer tank 51 is connected to the feed end of the concentration tank 52; and the discharge end of the concentration tank 52 is connected to the nitration unit 6.

[0027] In this embodiment, a stirrer can be installed in the dilute sulfuric acid buffer tank 51 to prevent crystallization. Furthermore, the dilute sulfuric acid is pumped into the vacuum evaporation and concentration tank 52 through an acid-resistant pump to further concentrate the sulfuric acid solution. The concentrated sulfuric acid is then directly supplied to the mixed acid system of the nitration unit 6 through an acid-resistant valve to form a nitrate-sulfur mixed acid with nitric acid, providing the necessary acidic environment for the nitration of o-xylene.

[0028] Specifically, such as Figure 1 and Figure 3 As shown, the nitrification treatment unit 7 includes a flue gas condenser 71, a nitrification absorption tower 72, and a dilute nitric acid receiving tank 73; the top of the denitrification tower 4 is connected to the air inlet of the flue gas condenser 71; the exhaust end of the flue gas condenser 71 is connected to the nitrification absorption tower 72; and the liquid discharge end of the nitrification absorption tower 72 is connected to the dilute nitric acid receiving tank 73.

[0029] In this embodiment, a water-cooled condenser is used to cool the high-temperature flue gas at the top of the denitrification tower 4 to 30°C, promoting the NO reduction. xIt forms tiny droplets with water vapor; in addition, a dilute nitric acid solution is sprayed into the nitrous oxide absorption tower 72 to absorb residual NO using countercurrent absorption. x It is converted into nitric acid, and the absorbent flows into the dilute nitric acid receiving tank 73 through the drain pipe.

[0030] Specifically, such as Figure 1 and Figure 2 As shown, the exhaust end of the nitrous oxide absorption tower 72 is connected to the tail gas treatment unit 10. The tail gas treatment unit 10 includes a tail gas absorption tower 101 and a decomposition tower 102; the feed end of the tail gas absorption tower 101 is connected to the exhaust end of the nitrous oxide absorption tower 72; the exhaust end of the tail gas absorption tower 101 is connected to the decomposition tower 102.

[0031] In this embodiment, the tail gas absorption tower 101 uses sulfuric acid for absorption. That is, through an oxidation-acidification reaction, the NO entering the tower is first oxidized to NO2, and then undergoes an oxidation-acidification reaction with sulfuric acid in a strongly acidic environment to generate nitric acid and nitrous acid. At the same time, the SO2 generated is also absorbed by sulfuric acid to form sulfate. Therefore, the absorbent can be directly returned to the mixed acid system of the nitration unit 6 or sent to the concentration tank 52 for reuse, realizing a closed-loop circulation of acid liquid.

[0032] In this embodiment, the tail gas absorption tower 101 is connected to an acid supply tank 11; the concentration tank 52 is connected to the acid supply tank 11; the acid supply tank 11 facilitates the adjustment of the sulfuric acid ratio for use as an absorbent in the tail gas absorption tower 101.

[0033] The overall system processing flow in this embodiment is as follows: Waste acid is first collected in a large waste acid tank 1, and then transported to the core equipment, the waste acid maturation reactor 2, via a circulating pump 9. Inside the reactor, equipped with stirring and heating functions, the waste acid undergoes a maturation process under constant temperature conditions, ensuring the dissolved organic nitro compounds react fully and completely eliminating the safety hazard of flotation in subsequent processes. The matured waste acid has its flow direction switched via a three-way valve 8; a portion flows back to the large waste acid tank 1 for continued circulation, while the other portion enters the waste acid heater 3. After being indirectly heated by steam in the waste acid heater 3, the concentrated waste acid enters the denitrification tower 4. Inside the tower, the highly acidic environment of the waste acid fully absorbs nitrogen oxides. The purified acid is then transported to the sulfuric acid buffer unit 5, which includes a dilute sulfuric acid buffer tank 51 and a concentration tank 52. After further concentration, the acid is directly reused in the mixed acid preparation process of the nitration unit 6. Meanwhile, the nitrate-containing flue gas at the top of the denitrification tower 4 enters the nitrate fume treatment unit 7 and is processed sequentially through the flue gas condenser 71 and the nitrate fume absorption tower 72. Finally, the dilute nitric acid product is recovered in the dilute nitric acid receiving tank 73. The unabsorbed tail gas enters the tail gas treatment unit 10 and is discharged after deep treatment by the tail gas absorption tower 101 and the decomposition tower 102. The absorbent required by the tail gas absorption tower 101 is supplied by the acid supply tank 11 and forms an acid mixing and circulation with the concentration tank 52 in the system.

Claims

1. A device system for treating waste acid and applying it to the nitration of o-nitroxylene, characterized in that: The system includes a waste acid tank (1), a waste acid maturation reactor (2), a waste acid heater (3), a denitrification tower (4), a sulfuric acid buffer unit (5), a nitration unit (6), and a nitrification fume treatment unit (7). The waste acid tank (1) is in cyclic communication with the waste acid maturation reactor (2). The discharge end of the waste acid maturation reactor (2) is connected to the feed end of the waste acid heater (3). The waste acid heater (3) is connected to the denitrification tower (4). The top of the denitrification tower (4) is connected to the nitrification fume treatment unit (7). The bottom of the denitrification tower (4) is connected to the sulfuric acid buffer unit (5). The sulfuric acid buffer unit (5) is connected to the nitration unit (6).

2. The apparatus system for spent acid treatment and application to nitro-o-xylene nitration according to claim 1, characterized by: The waste acid maturation reactor (2) is connected to the waste acid tank (1) through the first feed branch pipe; the waste acid maturation reactor (2) is connected to the waste acid heater (3) through the second feed branch pipe; the discharge end of the waste acid maturation reactor (2) is connected to the feed main pipe; the feed main pipe, the first feed branch pipe and the second feed branch pipe are connected through a three-way valve (8).

3. The apparatus system for spent acid treatment and application to nitro-o-xylene nitration according to claim 2, characterized by: The first material conveying branch pipe is equipped with a circulating pump (9).

4. The apparatus system for spent acid treatment and application to nitro-o-xylene nitration according to claim 3, characterized by: The sulfuric acid buffer unit (5) includes a dilute sulfuric acid buffer tank (51) and a concentration tank (52); the discharge end of the denitrification tower (4) is connected to the dilute sulfuric acid buffer tank (51); the dilute sulfuric acid buffer tank (51) is connected to the feed end of the concentration tank (52); and the discharge end of the concentration tank (52) is connected to the nitration unit (6).

5. The apparatus system for spent acid treatment and application to nitro-o-xylene nitration according to claim 4, characterized by: The nitrification treatment unit (7) includes a flue gas condenser (71), a nitrification absorption tower (72), and a dilute nitric acid receiving tank (73); the top of the denitrification tower (4) is connected to the inlet end of the flue gas condenser (71); the exhaust end of the flue gas condenser (71) is connected to the nitrification absorption tower (72); and the drain end of the nitrification absorption tower (72) is connected to the dilute nitric acid receiving tank (73).

6. The apparatus system for spent acid treatment and application to nitro-o-xylene nitration according to claim 5, characterized by: The exhaust end of the nitrate absorption tower (72) is connected to the tail gas treatment unit (10).

7. The apparatus system for spent acid treatment and application to nitro-o-xylene nitration according to claim 6, characterized by: The exhaust gas treatment unit (10) includes an exhaust gas absorption tower (101) and a decomposition tower (102); the feed end of the exhaust gas absorption tower (101) is connected to the exhaust end of the nitrate smoke absorption tower (72); the exhaust end of the exhaust gas absorption tower (101) is connected to the decomposition tower (102).

8. The apparatus system for treating waste acid and applying it to the nitration of o-nitroxylene according to claim 7, characterized in that: The tail gas absorption tower (101) is connected to an acid supply tank (11); the concentration tank (52) is connected to the acid supply tank (11).

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