Arrangement structure of nitric acid production device
By optimizing the equipment layout of the nitric acid production unit, placing the ammonia-air mixer and ammonia regulating valve group outside the compression plant, setting up hydrogen pipeline facilities externally, and keeping the liquid ammonia filter away from the compression plant, the fire hazard of the nitric acid unit was reduced, achieving cost savings and improved safety.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Utility models(China)
- Current Assignee / Owner
- Filing Date
- 2025-04-23
- Publication Date
- 2026-03-27
AI Technical Summary
Existing nitric acid production facilities have a high fire hazard classification, leading to increased construction investment and operating costs. Furthermore, the current standard classification method is too general and cannot effectively reduce fire hazards.
By optimizing the equipment layout of the nitric acid production unit, the ammonia-air mixer and ammonia regulating valve group are located outside the gable wall of the compression plant. The ammonia pipeline runs along the longitudinal wall and connects to the mixer. The hydrogen pipeline facilities are located outside the compression plant. The liquid ammonia filter is located far away from the compression plant, with a fireproof distance of not less than 4.5m, thereby reducing the risk of hydrogen leakage.
It significantly reduced the fire hazard category of some process units in the nitric acid plant, reduced fire separation distances, saved engineering investment and operating costs, improved the inherent safety of the design, and reduced construction difficulty and equipment investment.
Smart Images
Figure CN224048794U_ABST
Abstract
Description
TECHNICAL FIELD
[0001] The utility model belongs to nitric acid production technical field, especially relate to a nitric acid production device arrangement structure. BACKGROUND
[0002] The traditional nitric acid production device includes liquid ammonia evaporation, air filtration and compression, NH3 oxidation and NO oxidation, NOx mixture compression, NO2 absorption and acid production, tail gas treatment and other process units, and the typical plant layout includes two parts of a compression plant and an outdoor equipment area. Among them, the NH3 oxidation and NO oxidation, air compression, NOx mixture compression unit is arranged in the compression plant, and the main equipment includes an ammonia oxidation furnace, an oxidized nitrogen separator, a combined compressor (including an air compressor, a NOx compressor, a tail gas expander and a steam turbine or an electric motor), etc. The liquid ammonia evaporation unit and the NO2 absorption and acid production unit are arranged on one side of the compression plant, and the integrated air filter, the ammonia-air mixer and the ammonia conversion reduction reactor are arranged on the other side of the compression plant. In order to save the pipeline, the ammonia gas pipeline usually passes through the compression plant from the ammonia evaporation unit to the ammonia-air mixer and the ammonia conversion reduction reactor, resulting in that, in addition to the ammonia-air mixed gas pipeline in the compression plant, there will also be an ammonia gas pipeline (even including auxiliary facilities such as regulating valves and shut-off valves), and in addition, the ammonia oxidation furnace needs to use hydrogen gas for ignition, so the compression plant is also arranged with a hydrogen gas pipeline and a pressure regulating and shut-off facility. Although the units are different in fire hazard risk and production process due to the different treatment media, the fire hazard risk categories should also be different, but since the ammonia gas pipeline passes through the compression plant, there are ammonia-air mixed gas pipelines and ammonia oxidation furnaces in the compression plant, the current Chinese national standard "Design Fire Protection Standard for Petroleum and Chemical Industry Enterprises" GB 50160-2008 (2018 edition) article explains that the fire hazard risk category of the nitric acid production device is divided into class B as a whole, and the fire hazard risk classification in "Building Design Fire Protection Standard" GB 50016-2014 (2018 edition) (hereinafter referred to as "Building Standard") also involves oxidizing substances such as nitric acid and oxygen, and the fire hazard risk of these oxidizing substances is class B. These standard classification methods are relatively simple and general, resulting in that the fire hazard category of the nitric acid production device and the compression plant is relatively high, and the construction investment is relatively high, so it is necessary to optimize the arrangement of some equipment, instruments, valves, ammonia gas and hydrogen gas pipelines of the nitric acid production device, and reduce the fire hazard risk category of some process units of the nitric acid device. CONTENT OF THE UTILITY MODEL
[0003] The utility model aims at providing a nitric acid production device arrangement structure, which can reduce the fire hazard risk category of some process units of the nitric acid device, reduce the fireproof spacing between the nitric acid compression plant and the surrounding facilities, save the engineering investment and operation cost, facilitate the installation, maintenance and repair of the pipelines and equipment, and improve the essential safety of the design.
[0004] In order to achieve the above object, the utility model discloses a technical scheme that is a nitric acid production device arrangement structure, comprising a compression plant and the outdoor equipment area of the compression plant outside, the ammonia oxidation furnace is installed in the compression plant, the ammonia filter, the air filter, the ammonia air mixer, the ammonia conversion reduction reactor, the ammonia gas regulating valve group and the ammonia still are installed in the outdoor equipment area, the ammonia filter and the ammonia still are arranged outside the first longitudinal wall of the compression plant, the air filter and the ammonia conversion reduction reactor are arranged outside the second longitudinal wall of the compression plant, the ammonia air mixer and the ammonia gas regulating valve group are arranged outside the gable of the compression plant close to the ammonia oxidation furnace, the first ammonia gas pipeline connected to the ammonia filter of the ammonia filter extends to the outside of the first longitudinal wall of the compression plant, extends to the gable of the compression plant along the first longitudinal wall, is connected with the ammonia gas regulating valve group and the ammonia air mixer in proper order, the air pipeline connected to the air filter extends to the outside of the second longitudinal wall of the compression plant, extends to the gable of the compression plant along the second longitudinal wall, and is communicated with the ammonia air mixer.
[0005] The first ammonia gas pipeline and the air pipeline can be connected to the ammonia air mixer outside the gable of the compression plant along the longitudinal wall of the compression plant, the first ammonia gas pipeline does not need to pass through the compression plant again, the second ammonia gas pipeline is connected to the ammonia conversion reduction reactor by being arranged around the compression plant, the second ammonia gas pipeline does not need to pass through the compression plant again, there is no ammonia gas pipeline in the compression plant, the fire risk is reduced, the fireproof distance with the surrounding facilities is greatly reduced, the land area is saved, and the engineering construction investment is significantly reduced in the whole.
[0006] Preferably, the second ammonia gas pipeline connected to the ammonia still extends to the outside of the first longitudinal wall of the compression plant, extends to the gable of the compression plant along the first longitudinal wall, and then extends to the outside of the second longitudinal wall of the compression plant along the gable of the compression plant, and is connected with the ammonia conversion reduction reactor.
[0007] Preferably, the ammonia oxidation furnace is connected with a hydrogen source through a hydrogen pipeline, the hydrogen source is arranged outside the compression plant, and the auxiliary facilities installed on the hydrogen pipeline are also arranged outside the compression plant.
[0008] Preferably, the liquid ammonia filter of the ammonia filter is arranged away from the compression plant, and the fireproof distance is not less than 4.5 m.
[0009] Compared with the prior art, the nitric acid production device arrangement structure has the following advantages:
[0010] By arranging the ammonia air mixer and the ammonia gas regulating valve group outside the gable of the compression plant, the first ammonia gas pipeline and the air pipeline can be connected to the ammonia air mixer outside the gable of the compression plant along the longitudinal wall of the compression plant, the first ammonia gas pipeline does not need to pass through the compression plant again, the second ammonia gas pipeline is connected to the ammonia conversion reduction reactor by being arranged around the compression plant, the second ammonia gas pipeline does not need to pass through the compression plant again, there is no ammonia gas pipeline in the compression plant, the fire risk is reduced, the fireproof distance with the surrounding facilities is greatly reduced, the land area is saved, and the engineering construction investment is significantly reduced in the whole. BRIEF DESCRIPTION OF DRAWINGS
[0011] Figure 1 The utility model structure schematic diagram. DETAILED DESCRIPTION
[0012] The present invention will be further described below with reference to the accompanying drawings and specific embodiments.
[0013] like Figure 1 As shown, a layout structure for a nitric acid production unit includes a compression plant and an outdoor equipment area outside the compression plant.
[0014] The compression plant mainly houses an ammonia oxidation furnace 1 and a combined compressor 2. The outdoor equipment area mainly houses an ammonia evaporator 3, an ammonia filter, an air filter 6, an ammonia-air mixer 8, an ammonia conversion-reduction reactor 10, a nitric acid absorption tower 11, a bleaching tower 12, a start-up acid tank 13, an ammonia regulating valve group 14, and an ammonia stripper 15. The ammonia filter includes a liquid ammonia filter 4.1 and a gaseous ammonia filter 4.2, and the air filter 6 is an integrated air filter. After being filtered by the liquid ammonia filter 4.1, the liquid ammonia enters the ammonia evaporator 3 and evaporates into a gaseous state. The gaseous ammonia then enters the gaseous ammonia filter 4.2, passes through the first ammonia pipeline 5.1 and the ammonia regulating valve group 14, and enters the ammonia-air mixer 8. Air passes through the air filter 6 and the air pipeline... 7 is fed to the ammonia-air mixer 8, where ammonia and air are mixed. The mixed gas enters the ammonia oxidation furnace 1 to generate NO gas, which is partially oxidized to NO2. It then enters the combined compressor 2 for pressurization. The gas passes through the nitrogen oxide separator to remove condensed acid liquid. The gas phase is sent to the bottom of the nitric acid absorption tower 11 to generate nitric acid. The bleaching tower 12 bleaches the generated nitric acid. The start-up acid tank 13 is used to fill the nitric acid absorption tower 11 with dilute nitric acid liquid during start-up. The ammonia stripper 15 evaporates the liquid ammonia and enters the ammonia conversion reduction reactor 10 through the second ammonia gas pipeline 5.2. The tail gas is sent to the ammonia conversion reduction reactor 10, where ammonia selectively reacts with most of the NOx gas in the tail gas to generate a mixture of N2 and H2O, ensuring that the NOx emission of the tail gas meets the standards.
[0015] The ammonia evaporator 3, ammonia filter, nitric acid absorption tower 11, bleaching tower 12, start-up acid tank 13, and ammonia stripper 15 are located outside the first longitudinal wall of the compression plant; the air filter 6 and ammonia conversion reduction reactor 10 are located outside the second longitudinal wall of the compression plant; the ammonia-air mixer 8 and ammonia regulating valve group 14 are located outside the gable wall of the compression plant near the ammonia oxidation furnace 1.
[0016] The first ammonia gas pipeline 5.1 connected with the ammonia gas filter 4.2 extends to outside the first longitudinal wall of the compression plant, then extends to outside the gable of the compression plant along the first longitudinal wall, and is connected with the ammonia air mixer 8 and the ammonia gas regulating valve group 14 in sequence; the air pipeline 7 connected with the air filter 6 extends to outside the second longitudinal wall of the compression plant, then extends to outside the gable of the compression plant along the second longitudinal wall, and is connected with the ammonia air mixer 8, so that the first ammonia gas pipeline 5.1 and the air pipeline 7 can be connected to the ammonia air mixer 8 outside the gable of the compression plant along the longitudinal wall of the compression plant, and the first ammonia gas pipeline 5.1 does not need to pass through the compression plant again, thereby reducing the fire risk.
[0017] The second ammonia gas pipeline 5.2 connected with the ammonia evaporator 15 extends to outside the first longitudinal wall of the compression plant, then extends to outside the gable of the compression plant along the first longitudinal wall, and then extends to outside the first longitudinal wall of the compression plant along the gable of the compression plant, and is connected with the ammonia conversion reduction reactor 10, so that the second ammonia gas pipeline 5.2 is connected with the ammonia conversion reduction reactor 10 outside the compression plant, and the second ammonia gas pipeline 5.2 does not need to pass through the compression plant again, thereby reducing the fire risk. In the ammonia conversion reduction reactor 10, under the process conditions of a copper-chromium catalyst, an air speed of 10000h -1 -14000h -1 , a fuel ratio of 1.1-1.4, and a reaction temperature of 360-400℃, ammonia and NOx gas are selectively reacted to generate a mixture of N2 and H2O, the nitrogen oxide emission limit of the tail gas of nitric acid meets the requirement of 200mg / m 3 of the Special Emission Limit of Atmospheric Pollutants of Nitric Acid Industry, the design content of NOx in the tail gas is about 344mg / m 3 , in order to ensure the effect of ammonia reduction, excess ammonia is introduced, and the content of ammonia in the tail gas is controlled to be about 20mg / m 3 , after the ammonia gas and the tail gas are mixed by the pipeline mixer, the proportion of ammonia in the tail gas is 171mg / m 3 , and the volume ratio is 0.0283%, which is far below the lower limit of explosion. According to the principle of 4.3.1 of GB / T 27862-2011 / ISO 10156:2010 Chemical Hazard Classification Test Method Combustion Potential and Oxidizing Ability of Gases and Gas Mixtures, it can be known that the tail gas before denitration, the ammonia tail gas mixture, and the tail gas after denitration all do not have combustion potential and oxidizing ability. Since the ammonia conversion reactor and the ammonia gas pipeline are arranged outdoors, even if ammonia leaks from the flanges, valves and other sealing parts, it can easily diffuse and will not form an explosive gas environment. According to Table 3.1.1 of the Building Code, the tail gas treatment belongs to processing of non-combustible substances, and according to the description of Article 3.1.2 of the Building Code, the fire hazard of the unit can be classified as Class D.
[0018] In the embodiment, the ammonia oxidation furnace 1 is connected with a hydrogen source through a hydrogen pipeline 9, the hydrogen source is arranged outside the compression plant, and the auxiliary facilities installed on the hydrogen pipeline 9 are also arranged outside the compression plant, wherein the auxiliary facilities include a pressure regulating valve, a cut-off valve and the like, which control and protect the hydrogen pipeline 9, the hydrogen pipeline 9 enters the ammonia oxidation furnace 1 by welding, only one dismounting flange is arranged in the compression plant, no valve is arranged, the auxiliary facilities are arranged outside the compression plant, so that the total length of the hydrogen pipeline 9 entering the compression plant is less than 15 m, and by arranging the auxiliary facilities of the hydrogen pipeline 9 outside the compression plant and reducing the length of the hydrogen pipeline 9, the risk of hydrogen leakage in the compression plant can be reduced.
[0019] In addition, the liquid ammonia filter 4.1 is arranged away from the compression plant, and the fireproof distance should be greater than 4.5 m, so that the explosive dangerous mixture formed after the liquid ammonia leakage can be prevented from entering the compression plant.
[0020] There is no ammonia pipeline in the compression plant, the proportion of ammonia in the ammonia-air mixture is 9.5% to 10%, which is less than the lower limit of ammonia explosion (15.7%), and is not a flammable gas, even if the ammonia-air mixture leaks from the sealing point, it will only be further diluted in the air, and the ammonia concentration cannot form an explosive gas environment. Since the flammable and combustible medium involved in the compression plant is mainly hydrogen, by reducing the risk of hydrogen leakage and no longer arranging the ammonia pipeline in the compression plant, the fire hazard of the compression plant can be classified as Class D, the fire hazard classification of part of the units of the nitric acid device is reduced, and the fireproof distance with the surrounding facilities is greatly reduced, which can save the occupied area; after the fire hazard of the compression plant is classified as Class D, the steel structure 3 type is adopted, the secondary fire resistance grade can not adopt fire protection measures, which can reduce the construction difficulty and engineering cost; and the explosion hazard area of the compression plant is reduced, which can reduce the investment in explosion-proof electrical equipment; after the fire hazard classification of the compression plant and the tail gas treatment unit is reduced, according to different surrounding arrangement facilities, the occupied area can be saved by 30% to 50%, and the overall construction investment is significantly reduced.
Claims
1. A nitric acid production device arrangement, comprising a compression plant and an outdoor equipment area outside the compression plant, wherein an ammonia oxidation furnace (1) is installed in the compression plant; an ammonia filter, an air filter (6), an ammonia-air mixer (8), an ammonia conversion reduction reactor (10), an ammonia gas regulating valve group (14) and an ammonia evaporator (15) are installed in the outdoor equipment area; the ammonia filter (4) and the ammonia evaporator (15) are arranged outside the first longitudinal wall of the compression plant; the air filter (6) and the ammonia conversion reduction reactor (10) are arranged outside the second longitudinal wall of the compression plant; the ammonia-air mixer (8) and the ammonia gas regulating valve group (14) are arranged outside the gable of the compression plant close to the ammonia oxidation furnace (1); the first ammonia gas pipeline (5.1) connected with the gas ammonia filter (4.2) of the ammonia filter extends outside the first longitudinal wall of the compression plant, then extends along the first longitudinal wall outside the gable of the compression plant, and is sequentially connected with the ammonia gas regulating valve group (14) and the ammonia-air mixer (8); the air pipeline (7) connected with the air filter (6) extends outside the second longitudinal wall of the compression plant, then extends along the second longitudinal wall outside the gable of the compression plant, and is connected with the ammonia-air mixer (8). characterized in that The second ammonia gas pipeline (5.2) connected with the ammonia evaporator (15) extends outside the first longitudinal wall of the compression plant, then extends along the first longitudinal wall outside the gable of the compression plant, and is connected with the ammonia conversion reduction reactor (10) after extending along the gable of the compression plant outside the first longitudinal wall of the compression plant.
2. The nitric acid production plant arrangement according to claim 1, characterized in that, The ammonia oxidation furnace (1) is connected with a hydrogen source through a hydrogen pipeline (9); the hydrogen source is arranged outside the compression plant; and the auxiliary facilities installed on the hydrogen pipeline (9) are also arranged outside the compression plant.
3. The nitric acid production plant arrangement according to claim 1, c h a r a c t e r i z e d b y The liquid ammonia filter (4.1) of the ammonia filter (4) is arranged away from the compression plant, and the fireproof distance is not less than 4.5 m.
4. The nitric acid production plant arrangement according to claim 1, c h a r a c t e r i z e d b y