阅读说明：本技术 一种提高硝酸异丙酯合成后废酸安定性的处理方法 (Treatment method for improving stability of waste acid obtained after synthesis of isopropyl nitrate ) 是由 刘平 李海斌 丁金皓 武新军 聂国庆 杨亚妮 王育斌 于 2021-08-17 设计创作，主要内容包括：本发明属于有机合成废酸处理技术领域,提供了一种提高硝酸异丙酯合成后废酸安定性的处理方法。将液氮与硝酸异丙酯合成后产生的废酸分别通过液氮喷头和废酸喷头以喷雾的形式引入冷冻喷雾塔内,在液氮的冷却下废酸喷雾转变为废酸粉末,经传送带导入至负压酯酸分离塔后通过氮气吹扫,能够在液化过程中完成废酸与硝酸异丙酯蒸汽的分离,达到酯酸分离的目的,且分离后的硝酸异丙酯与氮气能够回收利用,而脱脂后的废酸经脱硝处理后也能够回收利用。本发明处理方法成本低廉,简便易行,可连续化处理,能够提升资源利用率,且分离后所得废酸酯含量小于0.1％,稳定性良好,使废酸后期脱硝处理安全风险显著降低。(The invention belongs to the technical field of organic synthesis waste acid treatment, and provides a treatment method for improving the stability of waste acid after isopropyl nitrate synthesis. Waste acid generated after synthesis of liquid nitrogen and isopropyl nitrate is respectively introduced into a freezing spray tower in a spray mode through a liquid nitrogen spray head and a waste acid spray head, the waste acid is converted into waste acid powder through spray under the cooling of the liquid nitrogen, the waste acid powder is introduced into a negative pressure ester acid separation tower through a conveyor belt and then is blown by nitrogen, the separation of the waste acid and isopropyl nitrate steam can be completed in the liquefaction process, the purpose of ester acid separation is achieved, the separated isopropyl nitrate and nitrogen can be recycled, and the degreased waste acid can be recycled after denitration treatment. The treatment method disclosed by the invention is low in cost, simple and feasible, can be used for continuous treatment, can improve the resource utilization rate, has the content of the waste acid ester obtained after separation of less than 0.1%, and is good in stability, so that the safety risk of the later-stage denitration treatment of the waste acid is obviously reduced.)

1. A treatment method for improving the stability of waste acid after isopropyl nitrate synthesis is characterized by comprising the following steps:

introducing liquid nitrogen and waste acid generated after production of isopropyl nitrate into a spray freezing tower in a spray form through a liquid nitrogen spray head and a waste acid spray head respectively to freeze the waste acid into waste acid powder, conveying the waste acid powder into a negative pressure ester acid separation tower through a conveyor belt, and introducing nitrogen to heat the waste acid powder under a negative pressure state to complete separation of the isopropyl nitrate and the waste acid; the waste acid after the ester removal is discharged from the bottom of the negative pressure ester acid separation tower and then can be connected to a denitration device for recycling after denitration treatment; the isopropyl nitrate steam and nitrogen are collected through an outlet at the upper part of a negative pressure ester acid separation tower, are subjected to acid removal and neutralization through an alkaline silica gel column, enter the isopropyl nitrate separation tower for cooling and condensation to form liquid, and are collected, and the nitrogen enters a nitrogen cooling tower from the upper part of the isopropyl nitrate separation tower for cooling and pressurization and then is recovered to be liquid nitrogen.

2. The treatment method for improving the stability of waste acid after isopropyl nitrate synthesis according to claim 1, wherein the spray freezing tower comprises a waste acid spray head and a liquid nitrogen spray head, wherein the waste acid spray head is arranged at the upper part of the spray freezing tower, the liquid nitrogen spray head is arranged at the middle part of the spray freezing tower, a waste acid powder receiving device is arranged at the lower part of the spray freezing tower and is connected with a continuously-operating conveyor belt, and the rotating speed of the conveyor belt is 0.5-0.8 m/s.

3. The treatment method for improving the stability of waste acid after isopropyl nitrate synthesis according to claim 2, wherein the atomization input speed of the waste acid in the spray freezing tower is 2-10L/min, the atomization input speed of liquid nitrogen is 1-10L/min, and the diameter of the frozen waste acid powder is 0.5-1 mm.

4. The treatment method for improving the stability of waste acid after isopropyl nitrate synthesis according to claim 1, wherein the height of the negative pressure ester-acid separation tower is 2-3 m, the diameter of the tower body is 1.2-1.7 m, a gas absorption device is arranged at the top of the negative pressure ester-acid separation tower, and a nitrogen guide device is arranged at the bottom of the tower kettle.

5. The treatment method for improving the stability of waste acid after isopropyl nitrate synthesis according to claim 4, wherein the pressure inside the negative pressure ester-acid separation tower is 0.02-0.03 MPa, the temperature is 8-12 ℃, the temperature for introducing nitrogen is 8-12 ℃, and the flow rate is 1-10L/min.

6. The treatment method for improving the stability of waste acid after isopropyl nitrate synthesis according to claim 1, wherein the flow rate of the mixed gas of isopropyl nitrate and nitrogen flowing into the isopropyl nitrate separation tower through the alkaline silica gel column is 2-10L/min.

7. The treatment method for improving the stability of waste acid after isopropyl nitrate synthesis according to claim 1, wherein the internal pressure of the isopropyl nitrate separation tower is 0.02-0.03 MPa, and the temperature is 5-15 ℃.

Technical Field

The invention relates to the technical field of organic synthesis waste acid treatment, in particular to a treatment method for improving the stability of waste acid after isopropyl nitrate synthesis.

Background

The main charge of the cloud blasting bomb is cloud blasting agent, also called air explosive. Cloud blasting is a high-energy fuel similar to explosives, which when detonated makes full use of the oxygen in the atmosphere in the blast zone. Under certain initiation conditions, the cloud blasting agent is thrown away, mixed with air and violently exploded.

The cloud blasting agent is generally composed of magnesium aluminum alloy powder and isopropyl nitrate. The isopropyl nitrate is a nitrate energetic material, and has the characteristics of low boiling point, volatility, high density compared with air, no color, easy mixing with air to form a flammable and explosive mixed system and the like. The existing production method of isopropyl nitrate is to react isopropanol with nitric-sulfuric mixed acid, and then a finished product is obtained through processes of ester-acid separation, water washing, drying and the like, and waste acid is generated in the production process. The waste acid is a mixture of unreacted mixed acid, water and residual reaction products after the nitration reaction is finished or products are separated, and the mass components of the waste acid are 80-85% of sulfuric acid, 13-18% of water, 0.1-0.5% of nitric acid and 0.1-0.5% of isopropyl nitrate. The synthesis of isopropyl nitrate belongs to esterification reaction and has reversibility. Therefore, the waste acid can be used as a product decomposition catalyst and has a catalytic decomposition effect, and the stability of the nitration product is reduced in most cases.

Most organic matters have certain dissolution characteristics in the waste acid, wherein the solubility of the nitration product is highest, when the waste acid contains the nitration product, the potential danger is generated, and if the waste acid is not properly treated and discharged, the partial accumulation can cause decomposition, combustion or explosion under certain conditions. Therefore, the waste acid contains a small amount of isopropyl nitrate, and the waste acid is easy to cause danger during recycling denitration treatment or neutralizing and discharging.

At present, domestic reports on the treatment of waste acid containing flammable and combustible energetic materials exist, and the treatment methods of waste acid containing conventional organic substances include the following three methods: firstly, organic substances and mixed acid are separated by an extraction method, for example, CN111559737A (published: 08/21/2020) discloses a method for continuously extracting nitration waste acid, wherein chlorobenzene is used for continuously extracting the waste acid for multiple times, and a chlorobenzene solution containing 2, 4-dinitrochlorobenzene and the nitration waste acid are finally obtained. CN101020586A (published: 2006, 02, 16) discloses a similar treatment method for waste acid containing nitro compounds in TNT production.

Another is a method using resin adsorption, and CN111517530A (published: 2020, 08/11) discloses a waste acid regeneration pretreatment method and system, in which free acid is adsorbed by resin for pretreatment in spray roasting process, the method is suitable for treating acid solution containing metal salt, but the used resin is converted into dangerous waste, which further increases environmental cost.

The last method is a static physical separation method, and CN111792997A (published: 10/20/2020) discloses a process method for improving the curing of waste acid, which returns the waste acid to a separator for multiple times for separation, increases the curing time of the waste acid to improve the curing degree, and realizes the separation of nitride from the waste acid. However, the method is only suitable for the nitrified substances with stable physical state in the waste acid, prolongs the contact time of the waste acid and the digestate, is easy to cause the decomposition of the nitrified substances, and has hidden production troubles.

In conclusion, no better method exists for treating the waste acid of isopropyl nitrate at present, and the defects of the conventional method treatment mainly comprise: (1) the extension of the standing separation time of the waste acid causes the increase of the contact time of the acid ester, and the nitrate is easy to decompose and release heat, thereby causing potential safety hazard; (2) adding inert substances to extract waste acid and extracting an organic phase, but removing a solvent at the later stage, so that the production cost is increased; (3) the waste acid is directly neutralized and diluted by using alkali liquor and discharged outside, a large amount of alkali water is consumed, the waste acid amount is increased, and meanwhile, a large amount of heat is released when high concentration in the waste acid is contacted with water, so that the decomposition and heat release of isopropyl nitrate or the generation of isopropyl nitrate steam are easily caused, and safety accidents occur.

Disclosure of Invention

In order to solve the blank of the related treatment technology for treating the waste acid after the synthesis of the isopropyl nitrate in the prior art and the current situation that the waste acid after the synthesis of the isopropyl nitrate cannot be well treated by the conventional waste acid treatment method, the invention provides a treatment method for improving the stability of the waste acid after the synthesis of the isopropyl nitrate.

In order to achieve the purpose, the invention adopts the following technical scheme:

waste acid generated in the process of preparing isopropyl nitrate is added into a spray freezing tower and is sprayed in an acid mist form by using a waste acid spray head, and liquid nitrogen is sprayed in a fine mist form by using a liquid nitrogen spray head around the waste acid spray head and is fully contacted with the acid mist. The acid mist is rapidly cooled into powder under the action of liquid nitrogen fog drops and falls into the lower layer of the spray freezing tower. Transferring the collected waste acid powder into a negative pressure ester acid separation tower through a conveyor belt, dropping the waste acid powder from top to bottom, introducing nitrogen into the bottom of the negative pressure ester acid separation tower for blowing from bottom to top, heating and dissolving the waste acid powder, extracting isopropyl nitrate from the upper part of the negative pressure ester acid separation tower along with the nitrogen, and separating the isopropyl nitrate material and liquid nitrogen through adsorption and cooling to obtain an isopropyl nitrate material and liquid nitrogen again; waste acid is heated into liquid drops, the liquid drops are discharged from the bottom of the negative pressure ester acid separation tower and then can be connected into a denitration device for denitration treatment and recycling, isopropyl nitrate steam and nitrogen are collected through an outlet at the upper part of the negative pressure ester acid separation tower, are subjected to deacidification and neutralization through an alkaline silica gel column, enter the isopropyl nitrate separation tower for cooling and condensation to form liquid, and then are collected, and nitrogen is transferred out from the upper part of the isopropyl nitrate separation tower again and enters a nitrogen cooling tower for cooling and pressurization to recover to liquid nitrogen.

Furthermore, the waste acid to be treated contains 80-85% of sulfuric acid, 13-18% of water, 0.1-0.5% of nitric acid and 0.1-0.5% of isopropyl nitrate.

Furthermore, the spray freezing tower comprises a waste acid spray head and a liquid nitrogen spray head, wherein the waste acid spray head is arranged at the upper part of the spray freezing tower, the liquid nitrogen spray head is arranged at the middle part of the spray freezing tower, the lower part of the spray freezing tower is provided with a waste acid powder receiving device and is connected with a continuously-running conveyor belt, and the rotating speed of the conveyor belt is 0.5-1.8 m/s.

Furthermore, the waste acid spray head is a water mist spray head, the pressure is 0.25MPa, the aperture is 0.5mm, the spray head is vertically installed downwards and is 20cm away from the top of the spray freezing tower, and the atomization input speed of the waste acid is 2-10L/min.

Furthermore, the liquid nitrogen nozzles are water mist nozzles, the pressure is 3.5-10 MPa, the pore diameter is 0.1mm, the number of the liquid nitrogen nozzles is 4, the liquid nitrogen nozzles are symmetrically distributed in a cross shape, an included angle of 60 degrees is formed between each nozzle and the horizontal plane, the distance from each nozzle to the top of the spray freezing tower is 43cm, and the liquid nitrogen atomization input speed is 1-10L/min.

Furthermore, the diameter of the frozen waste acid powder is 0.5-1 mm.

Further, the height of the negative pressure ester acid separation tower is 2-3 m, the diameter of the tower body is 1.2-1.7 m, a gas absorption device is installed at the top of the negative pressure ester acid separation tower, a nitrogen flow guide device is installed at the bottom of a tower kettle, a waste acid powder adding port is arranged at the upper part of the negative pressure ester acid separation tower, the adding port is vertically installed downwards, and the distance between the port and the top of the negative pressure ester acid separation tower is 1.2 m.

Further, a nitrogen guide device is arranged under the bottom of the negative pressure ester acid separation tower, a nitrogen guide pipe enters from the lower portion of the negative pressure ester acid separation tower, a top plate is additionally arranged above the nitrogen guide pipe and supported by an ejector rod, movable side plates are additionally arranged on the periphery of the top plate and are distributed in a shape like a Chinese character 'mi', an outlet of the guide device is bent and turned by 60 degrees and is punched down, and the distance between the guide device and the tower top is 1.6m, the distance between the guide device and the tower bottom is 42cm, and meanwhile, the guide device and an airflow baffle plate arranged in the bottom of the tower are 60 degrees.

Further, the internal pressure of the negative pressure ester acid separation tower is 0.02-0.03 MPa, and the temperature is 8-12 ℃. The temperature of the introduced nitrogen is 8-12 ℃, and the flow rate is 1-10L/min.

Further, the flow rate of the mixed gas of the isopropyl nitrate and the nitrogen flowing into the isopropyl nitrate separation tower through the alkaline silica gel column is 2-10L/min.

Further, the internal pressure of the isopropyl nitrate separating tower is 0.02-0.03 MPa, and the temperature is 5-15 ℃.

Compared with the prior art, the invention has the following beneficial technical effects:

1. the waste acid containing a small amount of isopropyl nitrate is quickly frozen by using a liquid nitrogen quick freezing technology, the waste acid liquid is converted into waste acid powder by using an atomization method for the waste acid and liquid nitrogen, and the waste acid is defrozen by nitrogen gas blowing, so that the contained isopropyl nitrate is removed from the acid liquid along with the nitrogen gas due to the characteristic of high volatility in the unfreezing process of the waste acid, and the waste acid is collected by post-treatment to be changed into the acid liquid again and enters the next recovery treatment process. The method can be used for completely separating the isopropyl nitrate from the waste acid, avoids the reduction of the stability of the energetic material caused by heating, impact, acidolysis and the like, increases the stability of the waste acid, is convenient for post-treatment processing, further recovers the isopropyl nitrate product, and improves the product yield.

2. The liquid nitrogen and the nitrogen used in the invention are used as auxiliary raw materials, can be repeatedly recycled, are environment-friendly, reduce the cost and avoid introducing new impurities in the separation process. In the whole process, the atomization freezing controllability of the waste acid is strong, wherein the separation degree of the isopropyl nitrate is more than 99.9 percent.

3. The separation method of liquid nitrogen freezing and nitrogen purging is used, so that the isopropyl nitrate is protected in an inert atmosphere in the whole process, the flash explosion danger (the flash point of the isopropyl nitrate is 12 ℃, the explosion limit is 2% -100%) caused by the accumulation of isopropyl nitrate steam is avoided, the condensation point difference between nitrogen and the isopropyl nitrate is large, the isopropyl nitrate steam is rapidly condensed into liquid after being cooled, and the separation of the isopropyl nitrate steam and the liquid at low temperature is facilitated.

4. After the waste acid is treated by the method for improving the stability of the waste acid, the content of organic matters in the treated gastric acid is reduced from 0.5-1% to less than 0.1% through detection, and the safety and stability are greatly improved. When the subsequent denitration process recovery treatment is carried out, the content of organic impurities in the denitration device is reduced, the pressure and the temperature are stable in the denitration process, and the risk is reduced.

Drawings

In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings used in the description of the embodiments or the prior art will be briefly described below, it is obvious that the drawings in the following description are only embodiments of the present invention, and for those skilled in the art, other drawings can be obtained according to the provided drawings without creative efforts.

FIG. 1 is a schematic view of a process flow of the treatment method for improving the stability of waste acid according to the present invention;

FIG. 2 is a front view of the spray head configuration of the spray freezing tower of the present invention;

FIG. 3 is a bottom view of the spray freezing tower nozzle arrangement of the present invention;

FIG. 4 is a schematic diagram of a negative pressure ester acid separation column according to the present invention;

FIG. 5 is a front view of a nitrogen diversion device at the bottom of the negative pressure ester acid separation column according to the present invention;

FIG. 6 is a top view of a nitrogen diversion device at the bottom of the negative pressure ester acid separation column of the present invention;

FIG. 7 is a bottom view of the nitrogen diversion apparatus at the bottom of the negative pressure ester acid separation column of the present invention;

FIG. 8 shows the results of gas chromatography analysis of waste acid before treatment in example 1 of the present invention;

FIG. 9 shows the results of gas chromatography analysis of the treated waste acid of example 1;

FIG. 10 shows the results of gas chromatography analysis of waste acid before treatment in example 2 of the present invention;

FIG. 11 shows the results of gas chromatography analysis of the treated waste acid of example 2;

FIG. 12 shows the results of gas chromatography analysis of waste acid before treatment in example 3 of the present invention;

FIG. 13 shows the results of gas chromatography analysis of the waste acid after treatment in example 3 of the present invention.

Wherein, in the figure:

1-waste acid tank; 2-a liquid nitrogen storage tank; 3-spray freezing tower; 4-a conveyor belt; 5-negative pressure ester acid separation tower; 6-basic silica gel column; 7-a nitrogen storage tank; 8-isopropyl nitrate separating tower; 9-nitrogen cooling tower; 10-a fan; 31-waste acid spray heads; 32-liquid nitrogen spray head; 51-a gas collection port; 52-spent acid powder feed inlet; 53-upper top plate; 54-a movable side plate; 55-an airflow baffle; 56-nitrogen gas conduit; 57-mandril.

Detailed Description

The invention provides a treatment method for improving the stability of waste acid after synthesis of isopropyl nitrate, which comprises the following steps:

waste acid generated in the process of preparing isopropyl nitrate is fed into the spray freezing tower 3, and is sprayed therein in the form of acid mist using a waste acid spray head 31, while liquid nitrogen is sprayed in the form of fine mist by a liquid nitrogen spray head 32 therearound and is brought into sufficient contact with the acid mist. The acid mist is rapidly cooled into powder under the action of liquid nitrogen fog drops and falls into the lower layer of the spray freezing tower 3. The collected waste acid powder is transferred to a negative pressure ester acid separation tower 5 through a conveyor belt 4 and falls down from top to bottom, meanwhile, nitrogen is introduced into the bottom of the negative pressure ester acid separation tower 5 to purge from bottom to top, the waste acid powder is heated and dissolved, wherein, the isopropyl nitrate is pumped out from the upper part of the negative pressure ester acid separation tower 5 along with the nitrogen, and then is separated by adsorption and cooling, the isopropyl nitrate material and the liquid nitrogen are obtained again, the waste acid is heated into liquid drops, and can be connected into a denitration device for denitration treatment and recycling after being discharged from the bottom of the negative pressure ester acid separation tower 5, the isopropyl nitrate steam and the nitrogen are collected by an outlet at the upper part of the negative pressure ester acid separation tower 5, after acid removal and neutralization through an alkaline silica gel column 6, the obtained product enters an isopropyl nitrate separation tower 8 to be cooled and condensed into liquid, and then the liquid is collected, and nitrogen is transferred out from the upper part of the isopropyl nitrate separation tower again to enter a nitrogen cooling tower 9 to be cooled and pressurized to recover into liquid nitrogen.

Further, a process flow diagram of the treatment method for improving the stability of waste acid after isopropyl nitrate synthesis provided by the invention is shown in fig. 1. The parameters of the equipment provided by the embodiment of the invention are not the only choices, and the relevant parameters of the equipment can be properly adjusted as long as the treatment process flow is satisfied.

Furthermore, the waste acid to be treated contains 80-85% of sulfuric acid, 13-18% of water, 0.1-0.5% of nitric acid and 0.1-0.5% of isopropyl nitrate.

Further, the spray freezing tower 3 comprises a waste acid spray head 31 and a liquid nitrogen spray head 32, wherein the waste acid spray head 31 is arranged at the upper part of the spray freezing tower, the liquid nitrogen spray head 32 is arranged at the middle part of the spray freezing tower, and a waste acid powder receiving device is arranged at the lower part of the spray freezing tower 3 and is connected with a continuously operating conveyor belt 4; the rotating speed of the conveyor belt 4 is 0.5-1.8 m/s;

furthermore, the spray head layout of the spray freezing tower 3 is shown in fig. 2 (front view) and fig. 3 (bottom view), the waste acid spray head 31 is a water spray head, the pressure is 0.25MPa, the aperture is 0.5mm, the spray head is vertically installed downwards and is 20cm away from the top of the spray freezing tower 3, and the atomization input speed of the waste acid is 2-10L/min; the liquid nitrogen spray heads 32 are water mist spray heads, the pressure is 3.5-10 MPa, the pore diameter is 0.1mm, the number of the liquid nitrogen spray heads is 4, the liquid nitrogen spray heads are symmetrically distributed in a cross shape, an included angle of 60 degrees is formed between each spray head and the horizontal plane, the distance between each spray head and the top of the spray freezing tower is 43cm, and the liquid nitrogen atomization input speed is 1-10L/min.

Furthermore, the diameter of the frozen waste acid powder is 0.5-1 mm.

Further, the height of the negative pressure ester acid separation tower 5 is 2-3 m, the diameter of the tower body is 1.2-1.7 m, the top of the negative pressure ester acid separation tower 5 is provided with a gas absorption device, the bottom of the tower kettle is provided with a nitrogen flow guide device, the upper part of the negative pressure ester acid separation tower 5 is provided with a waste acid powder adding port, the adding port is vertically and downwards arranged, the distance between the port and the top of the negative pressure ester acid separation tower 5 is 1.2m, and the structure of the negative pressure ester acid separation tower 5 is shown in fig. 3.

Further, a nitrogen guide device is arranged right below the bottom of the negative pressure ester acid separation tower 5, a nitrogen guide pipe 56 enters from the lower portion of the negative pressure ester acid separation tower, an upper top plate 53 is additionally arranged above the nitrogen guide pipe 56 and supported by a top rod 57, movable side plates 54 are additionally arranged on the periphery of the upper top plate 53 and are distributed in a shape like a Chinese character 'mi', an outlet of the nitrogen guide device bends 60 degrees and is flushed down, the distance between the flow guide device and the tower top is 1.6m, the distance between the flow guide device and the tower bottom is 42cm, the distance between the flow guide device and an airflow baffle plate arranged in the tower bottom is 60 degrees, and the front view, the top view and the bottom view of the nitrogen guide structure are respectively shown in fig. 5, fig. 6 and fig. 7.

Further, the internal pressure of the negative pressure ester acid separation tower 5 is 0.02-0.03 MPa, and the temperature is 8-12 ℃. The temperature of the introduced nitrogen is 8-12 ℃, and the flow rate is 1-10L/min.

Further, the flow rate of the mixed gas of isopropyl nitrate and nitrogen flowing into the isopropyl nitrate separation tower 8 through the alkaline silica gel column 6 is 2-10L/min.

Further, isopropyl nitrate steam is condensed into liquid in an isopropyl nitrate separation tower 8, nitrogen enters a nitrogen cooling tower 9 through the upper part of the isopropyl nitrate separation tower, and is liquefied again after pressurized cooling;

further, the internal pressure of the isopropyl nitrate separation tower 8 is 0.02-0.03 MPa, and the temperature is 5-15 ℃.

The technical solutions in the embodiments of the present invention will be clearly and completely described below, and it is obvious that the described embodiments are only a part of the embodiments of the present invention, and not all embodiments. All other embodiments, which can be derived by a person skilled in the art from the embodiments given herein without making any creative effort, shall fall within the protection scope of the present invention.

Example 1

Transferring the prepared isopropyl nitrate waste acid liquid into a spray freezing tower 3 by a diaphragm pump, wherein the atomization input speed of the waste acid is 4L/min, and the atomization input speed of liquid nitrogen is 4L/min. The diameter of the waste acid powder is controlled to be 0.8 mm-1 mm. The waste acid powder falls to the lower conveyor belt 4 at a conveying speed of 1m/s and is sent to the negative pressure ester acid separation tower 5.

The pressure of the negative pressure ester acid separation tower 5 is maintained at 0.02MPa, and the temperature is maintained at 5 ℃. The nitrogen introduced from the bottom is 5L/min, the temperature is 8 ℃, and the nitrogen collides with an airflow baffle 55 which is 60 degrees at the lower part in the kettle, deflects into upward airflow and meets waste acid powder falling from the upper part. And heating and liquefying the waste acid powder, dropping the waste acid powder into the bottom of the kettle in the form of liquid drops, continuously discharging and collecting the waste acid powder, and recycling the waste acid powder after denitration treatment after detection. The isopropyl nitrate is converted to steam which is removed from the upper gas collection port 51 in the column with nitrogen.

The mixed gas of the isopropyl nitrate and the nitrogen enters an isopropyl nitrate separation tower 8 after passing through an alkaline silica gel column 6. Controlling the flow rate of nitrogen containing isopropyl nitrate steam to be 8L/min, the temperature in the tower to be 9 ℃, and the vacuum pressure to be 0.02 MPa. Condensing isopropyl nitrate vapor into liquid, dropping the liquid into the bottom of the kettle in a liquid drop manner, continuously discharging and collecting the liquid, and collecting the liquid to a finished product tank after detection. The nitrogen enters a nitrogen cooling tower 9 through the upper part of the tower, is pressurized and cooled, and is liquefied again for recycling.

The same mass of waste acid samples before and after treatment in example 1 were taken, extracted with the same volume of n-heptane, and the obtained extract was subjected to gas chromatography detection, with the results of gas chromatography analysis of the waste acid before treatment in example 1 being shown in fig. 8 and the results of gas chromatography analysis of the waste acid after treatment in example 1 being shown in fig. 9. Comparative analysis example 1 analysis of the change in the content of isopropyl nitrate in the spent acid before and after the treatment showed that the residual amount of isopropyl nitrate was reduced from 0.5183% to a trace amount.

Example 2

Transferring the prepared isopropyl nitrate waste acid liquid into a spray freezing tower 3 by a diaphragm pump, wherein the atomization input speed of the waste acid is 10L/min, and the atomization input speed of liquid nitrogen is 6L/min. The diameter of the waste acid powder is controlled to be 0.7 mm-0.8 mm. The waste acid powder dropped to the lower conveyor belt 4 at a conveying speed of 1.2m/s and was sent to the negative pressure ester acid separation column 5.

The pressure of the negative pressure ester acid separation tower 5 is maintained at 0.03MPa, and the temperature is maintained at 8 ℃. The nitrogen introduced from the bottom has the inlet volume of 8L/min and the temperature of 9 ℃, collides with a baffle 55 which is 60 degrees at the lower part in the kettle, deflects into upward air flow and meets waste acid powder falling from the upper part. And heating and liquefying the waste acid powder, dropping the waste acid powder into the bottom of the kettle in the form of liquid drops, continuously discharging and collecting the waste acid powder, and recycling the waste acid powder after denitration treatment after detection. The isopropyl nitrate is converted to steam which is removed from the upper gas collection port 51 in the column with nitrogen.

The mixed gas of the isopropyl nitrate and the nitrogen enters an isopropyl nitrate separation tower 8 after passing through an alkaline silica gel column 6. Controlling the flow rate of nitrogen containing isopropyl nitrate steam at 5L/min, the temperature in the tower at 13 ℃ and the vacuum pressure at 0.03 MPa. Condensing isopropyl nitrate vapor into liquid, dropping the liquid into the bottom of the kettle in a liquid drop manner, continuously discharging and collecting the liquid, and collecting the liquid to a finished product tank after detection. The nitrogen enters a nitrogen cooling tower 9 through the upper part of the tower, is pressurized and cooled, and is liquefied again for recycling.

The same mass of waste acid samples before and after treatment in example 2 were taken, extracted with the same volume of n-heptane, and the obtained extract was subjected to gas chromatography, the gas chromatography analysis result of the waste acid before treatment in example 2 is shown in fig. 10, and the gas chromatography analysis result of the waste acid after treatment in example 2 is shown in fig. 11. Comparative analysis example 2 analysis of the change in the content of isopropyl nitrate in the spent acid before and after the treatment showed that the residual content of isopropyl nitrate was reduced from 0.7418% to 0.0691%.

Example 3

Transferring the prepared isopropyl nitrate waste acid liquid into a spray freezing tower 3 by a diaphragm pump, wherein the atomization input speed of the waste acid is 7L/min, and the atomization input speed of liquid nitrogen is 10L/min. The diameter of the waste acid powder is controlled to be 0.5 mm-0.6 mm. The powder dropped on the lower conveyor belt 4 and then was sent to the negative pressure ester acid separation column 5 at a conveying speed of 1.6 m/s.

The pressure of the negative pressure ester acid separation tower 5 is maintained at 0.03MPa, and the temperature is maintained at 10 ℃. The nitrogen introduced from the bottom is 2L/min, the temperature is 12 ℃, the nitrogen collides with a baffle 55 which is 60 degrees at the lower part in the kettle, deflects into upward airflow and meets waste acid powder falling from the upper part. And heating and liquefying the waste acid powder, dropping the waste acid powder into the bottom of the kettle in the form of liquid drops, continuously discharging and collecting the waste acid powder, and recycling the waste acid powder after denitration treatment after detection. The isopropyl nitrate is converted to steam which is removed from the upper gas collection port 51 in the column with nitrogen.

The mixed gas of the isopropyl nitrate and the nitrogen enters an isopropyl nitrate separation tower 8 after passing through an alkaline silica gel column 6. Controlling the flow rate of nitrogen containing isopropyl nitrate steam at 2L/min, the temperature in the tower at 15 ℃ and the vacuum pressure at 0.02 MPa. Condensing isopropyl nitrate vapor into liquid, dropping the liquid into the bottom of the kettle in a liquid drop manner, continuously discharging and collecting the liquid, and collecting the liquid to a finished product tank after detection. The nitrogen enters a nitrogen cooling tower 9 through the upper part of the tower, is pressurized and cooled, and is liquefied again for recycling.

The same mass of waste acid samples before and after treatment in example 3 were taken, extracted with the same volume of n-heptane, and the obtained extract was subjected to gas chromatography detection, with the results of gas chromatography analysis of the waste acid before treatment in example 2 being shown in fig. 12 and the results of gas chromatography analysis of the waste acid after treatment in example 3 being shown in fig. 13. Comparative analysis example 3 analysis of the waste acid before and after treatment for the change in the content of isopropyl nitrate showed a reduction in the residual amount of isopropyl nitrate from 0.8364% to a trace amount.

Example 4

Transferring the prepared isopropyl nitrate waste acid liquid into a spray freezing tower 3 by a diaphragm pump, wherein the atomization input speed of the waste acid is 2L/min, and the atomization input speed of liquid nitrogen is 1L/min. The diameter of the waste acid powder is controlled to be 0.5 mm-0.6 mm. The powder dropped on the lower conveyor belt 4 and then sent to the negative pressure ester acid separation column 5 at a conveying speed of 0.5 m/s.

The pressure of the negative pressure ester acid separation tower 5 is maintained at 0.025MPa, and the temperature is maintained at 7 ℃. The nitrogen introduced from the bottom is introduced at the inlet of 1L/min and the temperature of 10 ℃, and the nitrogen collides with a baffle 55 which is 60 degrees at the lower part in the kettle, deflects into upward airflow and meets waste acid powder falling from the upper part. And heating and liquefying the waste acid powder, dropping the waste acid powder into the bottom of the kettle in the form of liquid drops, continuously discharging and collecting the waste acid powder, and recycling the waste acid powder after denitration treatment after detection. The isopropyl nitrate is converted to steam which is removed from the upper gas collection port 51 in the column with nitrogen.

The mixed gas of the isopropyl nitrate and the nitrogen enters an isopropyl nitrate separation tower 8 after passing through an alkaline silica gel column 6. Controlling the flow rate of nitrogen containing isopropyl nitrate steam at 4L/min, the temperature in the tower at 5 ℃ and the vacuum pressure at 0.025 MPa. Condensing isopropyl nitrate vapor into liquid, dropping the liquid into the bottom of the kettle in a liquid drop manner, continuously discharging and collecting the liquid, and collecting the liquid to a finished product tank after detection. The nitrogen enters a nitrogen cooling tower 9 through the upper part of the tower, is pressurized and cooled, and is liquefied again for recycling.

Example 5

Transferring the prepared isopropyl nitrate waste acid liquid into a spray freezing tower 3 by a diaphragm pump, wherein the atomization input speed of the waste acid is 5L/min, and the atomization input speed of liquid nitrogen is 2L/min. The diameter of the waste acid powder is controlled to be 0.6 mm-0.7 mm. The powder dropped on the lower conveyor belt 4 and then was sent to the negative pressure ester acid separation column 5 at a conveying speed of 1.8 m/s.

The pressure of the negative pressure ester acid separation tower 5 is maintained at 0.023MPa, and the temperature is maintained at 6 ℃. The nitrogen introduced from the bottom of the kettle has the inlet volume of 10L/min and the temperature of 11 ℃, and the nitrogen collides with a baffle plate which is 60 degrees at the lower part in the kettle, deflects into upward airflow and meets waste acid powder falling from the upper part. And heating and liquefying the waste acid powder, dropping the waste acid powder into the bottom of the kettle in the form of liquid drops, continuously discharging and collecting the waste acid powder, and recycling the waste acid powder after denitration treatment after detection. The isopropyl nitrate is converted to steam which is removed from the upper gas collection port 51 in the column with nitrogen.

The mixed gas of the isopropyl nitrate and the nitrogen enters an isopropyl nitrate separation tower 8 after passing through an alkaline silica gel column 6. Controlling the flow rate of nitrogen containing isopropyl nitrate steam at 10L/min, the temperature in the tower at 10 ℃ and the vacuum pressure at 0.021 MPa. Condensing isopropyl nitrate vapor into liquid, dropping the liquid into the bottom of the kettle in a liquid drop manner, continuously discharging and collecting the liquid, and collecting the liquid to a finished product tank after detection. The nitrogen enters a nitrogen cooling tower 9 through the upper part of the tower, is pressurized and cooled, and is liquefied again for recycling.

The embodiments in the present description are described in a progressive manner, each embodiment focuses on differences from other embodiments, and the same and similar parts among the embodiments are referred to each other.

The previous description of the disclosed embodiments is provided to enable any person skilled in the art to make or use the present invention. Various modifications to these embodiments will be readily apparent to those skilled in the art, and the generic principles defined herein may be applied to other embodiments without departing from the spirit or scope of the invention. Thus, the present invention is not intended to be limited to the embodiments shown herein but is to be accorded the widest scope consistent with the principles and novel features disclosed herein.