阅读说明：本技术 一种高效节能的中压法制硝酸工艺 (Efficient and energy-saving process for preparing nitric acid by using medium-pressure method ) 是由 蔺向前 景江 王兴宇 王财 宋嘉琪 闫先龙 于 2021-08-17 设计创作，主要内容包括：本发明公开了一种高效节能的中压法制硝酸工艺,S1：将氨气在氧化反应器中进行高温加压的氧化反应以生成一氧化氮气体；S2：一氧化氮气体通过余热回收设备对其降温收集,在低温加压环境下持续对一氧化氮进行氧化反应以生成氮氧化合物气体,在对一氧化氮氧化过程中产生的热量同样由余热回收设备收集；S3：产生的氮氧化合物气体通入吸收塔,在低温加压的反应条件下与水生成硝酸,余热回收设备将产生的热量回收；S4：产生的硝酸溶液输入至蒸馏反应器中,利用余热回收设备回收的热量对蒸馏反应器进行加热以蒸馏生成浓硝酸,同时余热回收热备向预热处理器输送热量,对氧化反应器进行预加热。本发明能够有效提高对热量的回收利用,节约了能量的消耗。(The invention discloses an efficient and energy-saving process for preparing nitric acid by a medium-pressure method, which comprises the following steps of S1: carrying out high-temperature pressurized oxidation reaction on ammonia gas in an oxidation reactor to generate nitric oxide gas; s2: the nitric oxide gas is cooled and collected through waste heat recovery equipment, the nitric oxide gas is continuously subjected to oxidation reaction under a low-temperature pressurized environment to generate oxynitride gas, and heat generated in the nitric oxide oxidation process is collected through the waste heat recovery equipment; s3: introducing the generated oxynitride gas into an absorption tower, generating nitric acid with water under the reaction condition of low-temperature pressurization, and recovering the generated heat by using waste heat recovery equipment; s4: the generated nitric acid solution is input into a distillation reactor, the distillation reactor is heated by utilizing the heat recovered by the waste heat recovery device to generate concentrated nitric acid through distillation, and meanwhile, the waste heat recovery device is used for conveying heat to a preheating processor to preheat an oxidation reactor. The invention can effectively improve the recycling of heat and save the energy consumption.)

1. An efficient and energy-saving process for preparing nitric acid by a medium-pressure method is characterized by comprising the following steps:

s1: catalytic oxidation treatment of ammonia

Preheating an oxidation reactor before use to 100-300 ℃ through a preheating processor, fully mixing ammonia gas and air according to a certain proportion, introducing the mixture into the oxidation reactor, heating the oxidation reactor to 850-950 ℃ through a heating processor, controlling the pressure in the oxidation reactor to be within the range of 0.35-0.6 MPa, carrying out full catalytic oxidation reaction on the ammonia gas and the air, accelerating the generation of nitric oxide gas through a selective catalyst, and inhibiting the generation of nitrous oxide and nitrogen;

s2: nitric oxide oxidation treatment

Step S1, cooling the oxidation reactor to 180-220 ℃ by waste heat recovery equipment after the treatment, rapidly cooling the gas generated in the oxidation reactor by a rapid cooler, removing water condensed into liquid, conveying the cooled gas to an oxidation tower for enough time for pressurization and oxidation, and simultaneously recovering heat generated by nitric oxide oxidation in the oxidation tower by the waste heat recovery equipment so as to ensure that the oxidation of nitric oxide is stably carried out at room temperature to generate mixed gas of nitrogen dioxide, dinitrogen trioxide and dinitrogen tetroxide;

s3: nitric acid preparation by nitrogen-oxygen compound absorption

Introducing the mixed gas of nitrogen dioxide, dinitrogen trioxide and dinitrogen tetroxide generated in the step S2 into an absorption tower, reacting with water under the reaction condition of low temperature pressurization to generate nitric acid and nitric oxide, and recovering heat generated by the reaction through the waste heat recovery equipment so as to ensure the stable reaction;

s4: preparation of concentrated nitric acid

Inputting the nitric acid solution generated in the step 3 into a distillation reactor, adding a dehydrating agent into the distillation reactor, heating the distillation reactor by using the heat recovered by the waste heat recovery device to distill the nitric acid in the distillation reactor to remove part of water to prepare concentrated nitric acid, meanwhile, conveying the heat to a preheating processor by using the waste heat recovery device, and preheating the oxidation reactor by using the preheating processor to prepare for carrying out the next batch of step S1.

2. The efficient and energy-saving process for preparing nitric acid by using a medium-pressure method according to claim 1, which is characterized in that: and a plurality of layers of platinum nets are arranged in the oxidation reactor in the step S1 in a matching manner, and the platinum nets are used as catalysts for the ammonia oxidation reaction.

3. The efficient and energy-saving process for preparing nitric acid by using a medium-pressure method according to claim 2, which is characterized in that: the platinum net is additionally arranged in the oxidation reactor in the step S1, belongs to a selective catalyst, and can be added with ammonia gas to generate nitric oxide through oxidation and inhibit the ammonia gas from generating nitrous oxide and nitrogen gas through oxidation.

4. The efficient and energy-saving process for preparing nitric acid by using a medium-pressure method according to claim 1, which is characterized in that: the generation of the nitric acid solution in the step S3 is accompanied by generation of nitrogen oxide compounds dissolved in the nitric acid solution, and a bleaching step is added to the nitric acid solution after the completion of the treatment in the step S3 and during the transfer of the nitric acid solution to the distillation reactor in the step S4, whereby the nitrogen oxide compounds dissolved in the nitric acid solution are desorbed.

5. The efficient and energy-saving process for preparing nitric acid by using a medium-pressure method according to claim 4, which is characterized in that: after the completion of the treatment in step S3 and the completion of the transfer of the nitric acid solution to the distillation reactor in step S4, the nitrogen oxide compound gas remaining in the absorption tower is absorbed by the alkaline solution.

6. The efficient and energy-saving process for preparing nitric acid by using a medium-pressure method according to claim 5, which is characterized in that: the waste heat recovery equipment comprises a plurality of groups of heat exchange units, and each group of heat exchange units are respectively installed at the oxidation reactor, the oxidation tower and the absorption tower in a matched manner.

7. The efficient and energy-saving process for preparing nitric acid by using a medium-pressure method according to claim 6, which is characterized in that: the preheating processor adopts heating pipes spirally wound on the outer side wall of the oxidation reactor, the heating pipes are also spirally wound on the side wall of the distillation reactor, steam in a heat-carrying medium in the waste heat recovery device is heated by a steam superheater to generate superheated steam, and the superheated steam is introduced into each group of heating pipes to heat the oxidation reactor and the distillation reactor respectively.

8. The efficient and energy-saving process for preparing nitric acid by using the medium-pressure method according to claim 7, which is characterized in that: the superheated steam heated by the steam superheater heats the bleaching process and the alkali solution.

Technical Field

The invention relates to the technical field of chemical industry, in particular to a high-efficiency and energy-saving process for preparing nitric acid by a medium-pressure method.

Background

Nitric acid is an important basic chemical raw material, and is widely applied to the preparation of dyes, explosives, medicines, plastics, nitrogen fertilizers and chemical reagents, and is used for metallurgy and organic synthesis. At present, the domestic and external processes for producing nitric acid by using ammonia and air include a normal pressure method, a medium pressure method, a high pressure method and a double pressure method.

The method for preparing nitric acid by using a medium-pressure method means that the oxidation of ammonia and the absorption of nitrogen oxides are both carried out under the pressure of 0.35-0.6 MPa. The method has the advantages of compact equipment, improved production strength, low capital investment and special steel consumption, high absorption pressure, and NO₂The absorption rate is high, the concentration of the finished acid is high, and the volume of the absorption tower is small;

however, the traditional medium-pressure nitric acid preparation process still has more technical problems in energy consumption due to the defects of the process, and the energy is difficult to be efficiently utilized.

Disclosure of Invention

Aiming at the defects in the prior art, the invention aims to provide a process for preparing nitric acid by a medium-pressure method, which effectively improves the recycling of heat and saves energy consumption.

The technical scheme adopted by the invention for realizing the purpose is as follows: an efficient and energy-saving process for preparing nitric acid by a medium-pressure method comprises the following steps:

s1: catalytic oxidation treatment of ammonia

Preheating an oxidation reactor before use to 100-300 ℃ through a preheating processor, fully mixing ammonia gas and air according to a certain proportion, introducing the mixture into the oxidation reactor, heating the oxidation reactor to 850-950 ℃ through a heating processor, controlling the pressure in the oxidation reactor to be within the range of 0.35-0.6 MPa, carrying out full catalytic oxidation reaction on the ammonia gas and the air, accelerating the generation of nitric oxide gas through a selective catalyst, and inhibiting the generation of nitrous oxide and nitrogen;

s2: nitric oxide oxidation treatment

Step S1, cooling the oxidation reactor to 180-220 ℃ by waste heat recovery equipment after the treatment, rapidly cooling the gas generated in the oxidation reactor by a rapid cooler, removing water condensed into liquid, conveying the cooled gas to an oxidation tower for enough time for pressurization and oxidation, and simultaneously recovering heat generated by nitric oxide oxidation in the oxidation tower by the waste heat recovery equipment so as to ensure that the oxidation of nitric oxide is stably carried out at room temperature to generate mixed gas of nitrogen dioxide, dinitrogen trioxide and dinitrogen tetroxide;

s3: nitric acid preparation by nitrogen-oxygen compound absorption

Introducing the mixed gas of nitrogen dioxide, dinitrogen trioxide and dinitrogen tetroxide generated in the step S2 into an absorption tower, reacting with water under the reaction condition of low temperature pressurization to generate nitric acid and nitric oxide, and recovering heat generated by the reaction through the waste heat recovery equipment so as to ensure the stable reaction;

s4: preparation of concentrated nitric acid

Inputting the nitric acid solution generated in the step 3 into a distillation reactor, adding a dehydrating agent into the distillation reactor, heating the distillation reactor by using the heat recovered by the waste heat recovery device to distill the nitric acid in the distillation reactor to remove part of water to prepare concentrated nitric acid, meanwhile, conveying the heat to a preheating processor by using the waste heat recovery device, and preheating the oxidation reactor by using the preheating processor to prepare for carrying out the next batch of step S1.

And a plurality of layers of platinum nets are arranged in the oxidation reactor in the step S1 in a matching manner, and the platinum nets are used as catalysts for the ammonia oxidation reaction.

The platinum net is additionally arranged in the oxidation reactor in the step S1, belongs to a selective catalyst, and can be added with ammonia gas to generate nitric oxide through oxidation and inhibit the ammonia gas from generating nitrous oxide and nitrogen gas through oxidation.

The generation of the nitric acid solution in the step S3 is accompanied by generation of nitrogen oxide compounds dissolved in the nitric acid solution, and a bleaching step is added to the nitric acid solution after the completion of the treatment in the step S3 and during the transfer of the nitric acid solution to the distillation reactor in the step S4, whereby the nitrogen oxide compounds dissolved in the nitric acid solution are desorbed.

After the completion of the treatment in step S3 and the completion of the transfer of the nitric acid solution to the distillation reactor in step S4, the nitrogen oxide compound gas remaining in the absorption tower is absorbed by the alkaline solution.

The waste heat recovery equipment comprises a plurality of groups of heat exchange units, and each group of heat exchange units are respectively installed at the oxidation reactor, the oxidation tower and the absorption tower in a matched manner.

The preheating processor adopts heating pipes spirally wound on the outer side wall of the oxidation reactor, the heating pipes are also spirally wound on the side wall of the distillation reactor, steam in a heat-carrying medium in the waste heat recovery device is heated by a steam superheater to generate superheated steam, and the superheated steam is introduced into each group of heating pipes to heat the oxidation reactor and the distillation reactor respectively.

The superheated steam heated by the steam superheater heats the bleaching process and the alkali solution.

The invention has the beneficial effects that: because the oxidation of nitric oxide and the reaction of oxynitride and water to generate nitric acid solution are exothermic reactions and the reactions are more thorough in a low-temperature and high-pressure environment, the heat generated in the reaction process is fully collected by the preheating recovery equipment, and after ammonia gas is oxidized into nitric oxide by the oxidation reactor, the generated nitric oxide needs to be cooled to ensure the stable progress of the further oxidation of the nitric oxide, so the preheating recovery equipment is also arranged on the oxidation reactor to cool the generated high-temperature nitric oxide and absorb the heat;

in order to ensure high yield of nitric oxide when the oxidation reactor oxidizes ammonia gas, high-temperature pressurization control needs to be carried out on the reaction environment of the oxidation reactor, so that the oxidation reactor needs to be heated, firstly, the oxidation reactor is preliminarily heated to 100-300 ℃ through a preheating processor, and then, the oxidation reactor is heated to 850-950 ℃ through a heating processor; when the generated nitric acid solution is generated into concentrated nitric acid, the nitric acid solution also needs to be heated and distilled, and heat needs to be absorbed to ensure the stable preparation of the concentrated nitric acid;

collect the produced heat of low temperature environment reaction through preheating recovery plant, will need the condensation to handle the heat transfer and absorptive heat are collected to under acting on the reaction environment that needs carry out the heating, can effectively improve the recycle to the heat, practice thrift energy consumption.

Drawings

FIG. 1 is a schematic process flow diagram of the present invention.

Detailed Description

The technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the drawings in the embodiments of the present invention, and it is obvious that the described embodiments are only a part of the embodiments of the present invention, and not all of the 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

Referring to fig. 1, a high-efficiency and energy-saving process for preparing nitric acid by a medium-pressure method comprises the following steps:

s1: catalytic oxidation treatment of ammonia

Preheating an oxidation reactor before use to 100-300 ℃ through a preheating processor, fully mixing ammonia gas and air according to a certain proportion, introducing the mixture into the oxidation reactor, heating the oxidation reactor to 850-950 ℃ through a heating processor, controlling the pressure in the oxidation reactor to be within the range of 0.35-0.6 MPa, carrying out full catalytic oxidation reaction on the ammonia gas and the air, accelerating the generation of nitric oxide gas through a selective catalyst, and inhibiting the generation of nitrous oxide and nitrogen;

s2: nitric oxide oxidation treatment

Step S1, cooling the oxidation reactor to 180-220 ℃ by waste heat recovery equipment after the treatment, rapidly cooling the gas generated in the oxidation reactor by a rapid cooler, removing water condensed into liquid, conveying the cooled gas to an oxidation tower for enough time for pressurization and oxidation, and simultaneously recovering heat generated by nitric oxide oxidation in the oxidation tower by the waste heat recovery equipment so as to ensure that the oxidation of nitric oxide is stably carried out at room temperature to generate mixed gas of nitrogen dioxide, dinitrogen trioxide and dinitrogen tetroxide;

s3: nitric acid preparation by nitrogen-oxygen compound absorption

Introducing the mixed gas of nitrogen dioxide, dinitrogen trioxide and dinitrogen tetroxide generated in the step S2 into an absorption tower, reacting with water under the reaction condition of low temperature pressurization to generate nitric acid and nitric oxide, and recovering heat generated by the reaction through waste heat recovery equipment so as to ensure the stable reaction;

s4: preparation of concentrated nitric acid

Inputting the nitric acid solution generated in the step 3 into a distillation reactor, adding a dehydrating agent into the distillation reactor, heating the distillation reactor by using the heat recovered by the waste heat recovery device to distill the nitric acid in the distillation reactor to remove part of water to prepare concentrated nitric acid, meanwhile, conveying the heat to a preheating processor by using the waste heat recovery device, and preheating the oxidation reactor by using the preheating processor to prepare for the next batch of step S1.

Example 2

A plurality of layers of platinum nets are arranged in the oxidation reactor in the step S1 in a matching way, and the platinum nets are used as catalysts for the ammonia oxidation reaction; and a platinum net is additionally arranged in the oxidation reactor in the step S1, belongs to a selective catalyst, and can be used for adding ammonia gas to oxidize to generate nitric oxide and inhibiting the ammonia gas from oxidizing to generate nitrous oxide and nitrogen.

Example 3

Nitrogen oxides dissolved in the nitric acid solution are generated during the process of generating the nitric acid solution in step S3, and a bleaching process is added after the completion of the process of step S3 and during the process of transferring the nitric acid solution to the distillation reactor in step S4, whereby the nitrogen oxides dissolved in the nitric acid solution are desorbed.

After the completion of the treatment in step S3 and the completion of the transfer of the nitric acid solution to the distillation reactor in step S4, the nitrogen oxide compound gas remaining in the absorption tower is absorbed by the alkaline solution.

Example 4

The waste heat recovery equipment comprises a plurality of groups of heat exchange units, and each group of heat exchange units are respectively installed at the oxidation reactor, the oxidation tower and the absorption tower in a matching way.

The preheating processor adopts heating pipes spirally wound on the outer side wall of the oxidation reactor, the heating pipes are also spirally wound on the side wall of the distillation reactor, steam in a heat-carrying medium in the waste heat recovery device is heated by a steam superheater to generate superheated steam, and the superheated steam is introduced into each group of heating pipes to respectively heat the oxidation reactor and the distillation reactor.

The superheated steam heated by the steam superheater heats the bleaching process and the alkali solution.

Example 5

Because the whole oxidation of the nitric oxide belongs to exothermic reaction, and the reaction temperature in the oxidation tower is controlled at a lower level, the progress of the nitric oxide oxidation reaction can be effectively accelerated, and further the nitric oxide is efficiently oxidized into nitrogen dioxide, dinitrogen trioxide and dinitrogen tetroxide which can react with water to generate nitric acid, the heat generated by the nitric oxide needs to be continuously recycled in the treatment process of the oxidation tower so as to ensure the continuous and stable progress of the nitric oxide reaction;

the process of generating nitric acid by reacting oxynitride and water in the absorption tower belongs to exothermic reaction, and the reaction temperature in the absorption tower is controlled at a lower level to ensure the stable generation of the nitric acid, so that the heat generated in the treatment process of the absorption tower needs to be continuously recovered to ensure the stable generation of the nitric acid solution;

in order to ensure high yield of nitric oxide when the oxidation reactor oxidizes ammonia gas, high-temperature pressurization control needs to be carried out on the reaction environment of the oxidation reactor, so that the oxidation reactor needs to be heated, firstly, the oxidation reactor is preliminarily heated to 100-300 ℃ through a preheating processor, and then, the oxidation reactor is heated to 850-950 ℃ through a heating processor;

when the generated nitric acid solution is generated into concentrated nitric acid, the nitric acid solution also needs to be heated and distilled, and heat needs to be absorbed to ensure the stable preparation of the concentrated nitric acid;

consequently collect the produced heat of low temperature environment reaction through preheating recovery plant, will need the condensation to handle the heat transfer and the absorptive heat is collected to under acting on the reaction environment that needs carry out the heating, can effectively improve the recycle to the heat, practice thrift energy consumption.

Furthermore, it should be understood that although the present description refers to embodiments, not every embodiment may contain only a single embodiment, and such description is for clarity only, and those skilled in the art should integrate the description, and the embodiments may be combined as appropriate to form other embodiments understood by those skilled in the art.