Absorption Of Nitrogen Oxides Research Articles

CALCULATION PROGRAM OF THE ABSORPTION PROCESS IN NITRIC ACID PRODUCTION

The modern technological process is a product of design and modeling. Verification of theories and technical solutions can be carried out not on existing equipment but on mathematical models, by means of calculations. This increases the safety of research activities and speeds up the design process. For large research institutions and manufacturers, it is advisable to use specialized software such as MatLab, ASPEN or SimSci. Such environments have a large number of libraries and applications, which make them multifunctional. At the same time, the vast majority of users use only a small number of narrowly specialized functions that correspond to the direction of their activity. Mastering programming skills has become an integral part of modern education. Creating calculation programs based on mathematical models is not a difficult task for scientists. The rapid development of programming languages and technologies allows choosing the most appropriate ways of creating programs. According to experts, C# has been in the top 5 popular programming languages for many years. The use of this language is closely related to the .NET technology, which is intended for creating cross-platform applications. Microsoft Corporation provides the possibility of free use of its product MS Visual Studio, which also includes C#. The article describes a program created for use in researching the operation of an absorption column for the absorption of nitrogen oxides in the production of nitric acid. When developing the program, a standard calculation algorithm was used, according to which industrial devices operating in Ukraine were calculated. The algorithm also takes into account the latest information on the influence of technological parameters and physico-chemical processes. The program is created with a minimalistic interface and data entry options both from the program window and from a text file. The results of calculating the influence of oxygen addition on the concentration of nitrogen oxides in the discharge gas are given. The main purpose of the program is to study the operation of the column as an object of automation. The proposed program can be supplemented with new options, such as automatic calculation of gain coefficients for specified channels, batch processing based on data from a file, and others. Also, the program can be used for teaching students and performing research.

Absorption and partitioning mechanism of nitrogen oxides by typical greening species of tree in Beijing

In this study, we analyzed the uptake of nitrogen dioxide (NO2) and its processes of distribution in various organs of different typical greening species of trees and the differences in its uptake by these different species using the 15N stable isotope tracer method under the gradient of three NO2 concentration treatments, namely, low, medium and high. These experiments were conducted using one-time artificial fumigation to provide necessary data and theoretical support for the selection and application of species of greening trees in urban gardens. The treatments of fumigation with different concentrations of NO2 showed that the leaves of the six species of trees had the highest content of 15N. The organs that were the most effective at taking up 15N were the leaves in broadleaf trees and the branches in conifers. The content of 15N per unit of the leaves (0.0058–2.0486 μg/g) increased in parallel with the concentration of fumigant and then was rapidly transported to various organs in the tree. This caused different degrees of changes in other organs. The total content of 15N per unit was higher in the broadleaf species (0.0129–2.3171 μg/g) than in the conifers (0.0296–0.1260 μg/g). The leaves of broadleaf trees were the most effective at taking up 15N (0.0054–1.3228 %) under medium and high concentrations of fumigant with the exception of ginkgo. The ability of each organ of the other broadleaf species was leaves>branches>trunks>roots, and the branches of conifers were the most effective parts of the trees at taking up NO2 under three concentrations of fumigants (0.0789–0.4005 %). The highest rate of distribution of 15N was found in the leaves (48.14–99.53 %) in all six species under different concentrations of fumigant, and the distribution in the other organs varied to different degrees.

Process Intensification of Absorption of Nitrogen Oxides in the Manufacturing of Nitric Acid and Techno-economic Assessment: Use of Ozone

Process Intensification of Absorption of Nitrogen Oxides in the Manufacturing of Nitric Acid and Techno-economic Assessment: Use of Ozone

Modelling the absorption of nitrogen oxides by ferrous chelate solution in rotating packed bed

ABSTRACT With mushrooming growth of coal-based industry, the discharged tail gas containing nitrogen oxides had given significant effect on air quality and people’s health in China. Therefore, more stringent NOx emission standards were proposed. Among many technologies, wet scrubbing technology may be an effective way to solve the above problem, but it was limited by absorption of nitrogen oxides. Therefore, rotating packed bed (RPB) was used to intensify the absorption process of nitrogen oxides by ferrous chelate solution. To speed up its industrialization, a theoretical model was proposed by considering chemical reactions, gas and liquid mass transfer rate, liquid holdup and gas–liquid effective interfacial area. The effects of high gravity factor, gas velocity, gas–liquid ratio, temperature and concentration of ferrous chelate solution on NOx removal efficiency were conducted by model and also compared with experimental results. With high absorption efficiency and small equipment size in RPB, it had a great potential to apply in the absorption other harmful matters.

Estimating NOx removal capacity of urban trees using stable isotope method: A case study of Beijing, China

It is widely recognized that green infrastructures in urban ecosystems provides important ecosystem services, including air purification. The potential absorption of nitrogen oxides (NOx) by urban trees has not been fully quantified, although it is important for air pollution mitigation and the well-being of urban residents. In this study, four common tree species (Sophora japonica L., Fraxinus chinensis Roxb., Populus tomentosa Carrière, Sabina chinensis (L.)) in Beijing, China, were studied. The dual stable isotopes (15N and 18O) and a Bayesian isotope mixing model were applied to estimate the sources contributions of potential nitrogen sources to the roadside trees based on leaf and soil sampling in urban regions. The following order of sources contributions was determined: soil > dry deposition > traffic-related NOx. The capacity of urban trees for NOx removal in the city was estimated using a remote sensing and GIS approach, and the removal capacity was found to range from 0.79 to 1.11 g m−2 a−1 across administrative regions, indicating that 1304 tons of NOx could be potentially removed by urban trees in 2019. Our finding qualified the potential NOx removal by urban trees in terms of atmospheric pollution mitigation, highlighting the role of green infrastructure in air purification, which should be taken into account by stakeholders to manage green infrastructure as the basis of a nature-based approach.

Trapping nitrous gases during nitric acid leaching of sulfide concentrates

Gas-air mixtures that form in nitric acid leaching of sulfide raw materials possess the following peculiarities making a negative impact on trapping of nitrogen oxides: elevated temperature, different oxidation level of nitrogen oxides, slow oxidation of NO in region of low concentrations, and instability of the resulting gas-air mixture flow. Therefore, well-known methods of trapping nitrous gases shall be adapted to specific sulfide raw material. We propose a process flow diagram for trapping nitrous gases formed during nitric acid leaching of sulfide concentrates at atmospheric pressure on the example of Zhezkazgan concentrate. The paper addresses theoretical aspects of the use of water-ore pulp, concentrated sulfuric acid, process water and alkaline agents for trapping nitrous gases, and typical reactions of interaction of the proposed absorbents with nitrogen oxides. The choice of water-ore pulp as an absorber was made because of similarity between the mechanism of absorption of nitrogen oxides for neutral and alkali ore suspensions and the one for alkali solutions: nitrogen dioxide and nitrous anhydride are absorbed with formation of a solution of nitrates and nitrites. Due to availability in a liquid phase of ferrous iron along with NO2 and N2O3, acidic suspensions are also capable to absorb nitric oxide, to some extent, with formation of Fe(NO)SО4 complex. Process water absorbs only nitrogen dioxide, with formation of nitric and nitrous acids. Nitrous acid is an unstable compound in acidic environments and decomposes with formation of water and nitrogen oxide. At the stages of trapping nitrogen oxides with water-ore pulp and process water (circulating solution), it is recommended conditioning of gas-air mixtures by choosing the volume of additionally introduced air, in an amount to provide the highest rate of nitrogen oxide oxidation. At the stages of sulfuric acid and alkaline trapping of nitrogen oxides, it is recommended conditioning of gas-air mixtures by selecting the volume of additionally introduced air and the oxidation time of nitrogen oxide that provide an equimolecular mixture of NO and NO2. A distinctive feature of the use of water-ore pulp, concentrated sulfuric acid, process water and alkaline agents for trapping nitrous gases is possibility to use the products of absorption at the stage of sulfide concentrate leaching. The extended tests of trapping nitrous gases have been conducted. The plant capacity by the gas-air mixture ranged 17–21 m3/h, and by leached concentrate — 12–15 kg/h. In this case, the degree of capturing nitrous gases reached 96.8%. Return of the products of absorption of nitrous gases in the form of condensate, water-ore pulp, nitrosyl sulfuric acid, nitric acid solution, nitritenitrate lye allows to reduce the nitric acid consumption by 7–10 times relative the values obtained without using the trapping system. In this case, the degree of copper extraction into the leaching solution was 97.7%. The extraction degree of silver, rhenium, zinc was respectively 98.0%, 99.0%; 98.5%.

PECULIARITIES OF ABSORPTION OF SULFUR DIOXIDE AND NITROGEN OXIDE IN SUSPENSIONS AND SOLUTIONS OF MANGANESE COMPOUNDS

It is proposed to use manganese compounds to reduce emissions of sulfur and nitrogen oxides, large deposits of which are in Ukraine. The results of experimental studies of the binding of sulfur dioxide and potassium permanganate of nitric oxide in water by manganese oxide are presented. In the experiments, the model gas in the form of small bubbles was passed through the reactor with liquid. Heat and mass transfer processes between the gas and liquid phases occurred on the bubble surface. The gas-liquid contact time is the bubble rise time. The absorption reactions take place in the liquid phase. Complete absorption of sulfur dioxide takes place in an acidic environment, provided that the molar ratio MnO2 / SO2 is not less than 2. The reaction product is manganese sulfate, which is a useful product. The maximum absorption of nitrogen oxide is achieved at a molar ratio of KMnO4 / NO not less than 5. The reaction forms a precipitate of manganese oxide, which can later be used in the desulfurization process. Bibl. 12, fig. 6, tab. 3.

Absorption of nitrogen oxides into sodium hydroxide solution in a packed column: Effect of gas flowrate and temperature

Absorption of nitrogen oxides into sodium hydroxide solution in a packed column: Effect of gas flowrate and temperature

Nitrogen oxides absorption into sodium hydroxide solution in a packed column: effect of naoh concentration

Nitrogen oxides absorption into sodium hydroxide solution in a packed column: effect of naoh concentration

An investigation of nitrogen Oxide Absorption in packed columns

An investigation of nitrogen Oxide Absorption in packed columns

Measurement and modeling of nitrogen oxides absorption in a pressurized reactor relevant to CO2 compression and purification process

The removal of nitrogen oxides under a high pressure has been widely accepted as an effective method for the treatment of oxy-fuel combustion flue gas. The high pressure promotes the oxidation of NO to NO2, subsequently removed by water to form nitric acid. However, both the measurement and modeling of nitrogen oxides absorption shows uncertainties. To quantify the nitrogen mass balance, gas-phase NO/NO2 and HNO2 were measured online, whereas liquid-phase HNO2 and HNO3 were analyzed offline. Nitrogen mass balance was achieved with a relative error within ±8%. To improve modeling accuracy, a novel multiparameter optimization method was proposed. Mass transfer coefficients of NO2/NO, rate constant of NO oxidation, surface area, and volume of liquid were optimized. The absorption of NO2 into a liquid was dominated by gas-phase mass transfer with the mass transfer coefficient decreasing from 1.77 × 10―4 mol m−2 s-1 Kpa-1 to 1.26 × 10―4 mol m−2 s-1 Kpa-1 with the increase of reactor pressure from 5 bar to 20 bar. The pressure dependent rate constant for NO oxidation agreed with gas-phase NO oxidation experimental measurement. It first decreased with the reactor pressure from 5 bar to 15 bar followed by an increase from 15 bar to 20 bar. The surface area of liquid decreased while the liquid volume increased with the rising reactor pressure indicating that liquid droplets were formed by gas bubbling and attached onto the inner surface of the reactor. This study resolved the uncertainties in measurement and modeling of the nitrogen oxides absorption process.

Utilization of electrochemical treatment and surface reconstruction to achieve long lasting catalyst for NOx removal

The development of catalysts has seen tremendous growth recently but most strategies only report utilization of catalysts for a few initial cycles without taking into account the influence of oxygen poisoning. Here, the magnetic Fe3O4@EDTA-Fe (MEFe, having a core Fe3O4 particle with EDTA-Fe coating) was investigated as a model catalyst for long-term recycling for the removal of nitrogen oxide (NOx) from NO/O2 mixture, followed by N2O recovery. The concentration of oxygen in the flue gas was found to have a strong impact on NOx absorption and catalytic response. To circumvent the oxygen poisoning, the MEFe was subjected to electrochemical treatment in the presence of neutral red (N.R.) and NO removal efficiency was ∼95 % noted. Furthermore, the surface of the catalyst degraded significantly (p < 0.05) after 6–7 repetitive cycling due to surface catalytic reactions, surface poisoning, oxidation of metallic species as well as residual stresses. The MEFe surface was reconstructed after 7 cycles using EDTA solution and Fe source to achieve similar surface coating as the fresh MEFe catalyst. The reconstructed MEFe exhibited similar NOx absorption capability as the fresh MEFe and the reconstruction loop was repeated several times to achieve long term cycling, which make the catalyst cost-effective. Hence, it is proposed that a successful regeneration process can be employed for promising, sustainable and long-lasting catalytic treatment of air pollutants.

Measurement and modeling of nitrogen oxides absorption in a pressurized reactor relevant to CO2 compression and purification process

The removal of nitrogen oxides under a high pressure has been widely accepted as an effective method for the treatment of oxy-fuel combustion flue gas. The high pressure promotes the oxidation of NO to NO2, subsequently removed by water to form nitric acid. However, both the measurement and modeling of nitrogen oxides absorption shows uncertainties. To quantify the nitrogen mass balance, gas-phase NO/NO2 and HNO2 were measured online, whereas liquid-phase HNO2 and HNO3 were analyzed offline. Nitrogen mass balance was achieved with a relative error within ±8%. To improve modeling accuracy, a novel multiparameter optimization method was proposed. Mass transfer coefficients of NO2/NO, rate constant of NO oxidation, surface area, and volume of liquid were optimized. The absorption of NO2 into a liquid was dominated by gas-phase mass transfer with the mass transfer coefficient decreasing from 1.77 × 10−4 mol m−2 s−1 Kpa−1 to 1.26 × 10−4 mol m−2 s−1 Kpa−1 with the increase of reactor pressure from 5 bar to 20 bar. The pressure dependent rate constant for NO oxidation agreed with gas-phase NO oxidation experimental measurement. It first decreased with the reactor pressure from 5 bar to 15 bar followed by an increase from 15 bar to 20 bar. The surface area of liquid decreased while the liquid volume increased with the rising reactor pressure indicating that liquid droplets were formed by gas bubbling and attached onto the inner surface of the reactor. This study resolved the uncertainties in measurement and modeling of the nitrogen oxides absorption process.

The Effect of the Number of Fibers in Hollow Fiber Membrane Modules for NOx Absorption

As a type of gas that contributes to air pollution, nitrogen oxide (NOx) has harmful effects on humans and the environment. Among several types of NOx, nitric oxide (NO) and nitrogen dioxide (NO2) are most commonly found in air. The utilization of membranes as reactors is a system that combines chemical reactions with the separation process through membranes to increase the conversion of the reaction. This study investigated the absorption process by utilizing a hollow fiber membrane module (polysulfone) as a bubble reactor with H2O2 (0.5 wt. %) and HNO3 (0.5M) as the absorbent. NOx feed gas was flown into the tube side of the membrane; the shell side was filled with static H2O2 and HNO3 and the shell input and the tube output flow were closed to create gas bubbles. The experimental results showed that the absorption efficiency increased, but the mass transfer coefficient and flux decreased as the number of fibers in the membrane module increased at the same feed gas flow rate. The NOx loading is relatively constant as the amount of fiber in the membrane module increased at the same feed gas flow rate. The experimental results also showed that the mass transfer coefficient, flux, and NOx loading increased with increasing feed gas flow rate, but the absorption efficiency decreased when using the same number of fibers in the membrane module. The maximum NOx absorption efficiency achieved in this study was 94.6% at the feed gas flow rate of 0.1 L/min, using a membrane module with 48 fibers.

Investigation of Absorption and Emission Spectra of Nitrogen Oxides NO, N2O, NO2, and N2O4

The absorption and emission spectra of NO, N2O, NO2, and N2O4 nitrogen oxides have been studied with high and intermediate spectral resolution in the range 0.25–25 μm under conditions of self-broadening and nitrogen-induced broadening at room and enhanced temperatures. The experimental data on the spectral transmittance function have been parameterized by the two-parameter equivalent mass method. The rovibrational band intensities have been measured and the data on the absorption induced by the pressure in collisions of NO2–NO2 molecules have been obtained.

DETERMINATION OF OPTIMAL CONDITIONS FOR EFFECTIVE ABSORPTION OF NITROGEN AND SULFUR OXIDES BY IRON-MANGANESE CONCRETIONS

Iron-manganese concretions (IMC) absorption characteristic and composition of the material was studied. The active component in it is manganese (IV) oxide MnO2. A method is proposed for using a suspension of iron-manganese concretions ore to capture industrial emissions: nitrogen oxide (II) NO and sulfur oxide (IV) SO2. This method involves the reaction of the absorption of nitrogen oxide (II) NO by manganese (IV) oxide MnO2 in the presence of nitric acid HNO3. The formation of manganese nitrate Mn(NO3)2 occurs. Also, the reaction of the absorption of sulfur oxide (IV) SO2 by manganese (IV) oxide MnO2 with the formation of manganese sulfate MnSO4 takes place. Special installations for research and development of the process of sorption were developed. The results of experimental studies of the sorption process of nitrogen oxide (II) NO and sulfur oxide (IV) SO2 by a suspension based on IMC are presented. The main parameters of the influence on the process of the system operation are indicated: time for reaching a constant mode, temperature of the working suspension, method of mixing. Tables and figures are given showing the experimental results of the processes with various factors of influence. Optimal conditions for maximum efficient conduction of nitrogen oxide and sulfur dioxide absorption process were determined for adsorption of these gases to 85% and 99%, respectively, from the model mixtures that corresponds to the waste gases. Comparative analysis of sorption processes of NO and SO2 was performed.

Efficiency Improvement in Reactive Absorption of Nitrogen Oxides

Abstract This study is focused on reactive absorption of nitrogen oxides created during calcium nitrate fertilizer production. A functional mathematical process model was set up to verify the proce...

Simultaneous Removal of SO2 and NOX by a Combination of Red Mud and Coal Mine Drainage

Simultaneous removal of sulfur dioxide (SO2) and nitrogen oxides (NOX) is an important research field in air pollution control. The combination application of red mud (RM) with coal mine drainage as absorbent in simultaneous desulfurization and denitrification is an innovative attempt. In this study, a series of bubbling and spray tower tests were conducted to improve desulfurization and denitration abilities. Effects of RM concentration, gas flow, liquid–gas ratio, and SO2 concentration were investigated in the test. Our results indicated that SO2 removal efficiency depends primarily on RM concentration, gas flow, and the liquid–gas ratio. In the denitration test, the denitration characteristics of the absorbent were not consistent with industrial requirements, but denitration ability could be improved by the addition of an oxidant. In addition, influence of interactions between SO2 and NOX was observed, and low concentrations of SO2 could enhance NOX absorption, whereas high SO2 concentrations inhibit NOX absorption. Meanwhile, NOX concentration has a negligible effect on SO2 removal. Under optimized conditions, such as with RM concentration of 12%, gas flow of 40 L/min, liquid–gas ratio of 20 L/m3, absorbent renewal rate of 15%, and a sodium chlorite concentration of 1.9%, desulfurization efficiency is >99.0%, and denitration efficiency ranges from 45.0% to 47.0%. RM and mine water slurry show strong potential as a novel absorbent for the simultaneous removal of SO2 and NOX. This study provides a potential feasible technology for reusing RM and coal mine drainage with low cost instead of conventional method.

Nitrogen oxides absorption into aqueous nitric acid solutions containing hydrogen peroxide tested using a cables-bundle contactor

This work aims to study the removal of dilute nitrogen oxides from gaseous effluents by absorption into aqueous nitric acid solutions containing or not hydrogen peroxide. NOx absorption tests (pNOx = 50 Pa with a varying composition) were performed in a cables-bundle contactor at ambient conditions. Tests runs were carried out with the recycling of the absorbent solution (0–8 mol/l for HNO 3 and 0–2 mol/l for H 2 O 2 ) allowing to observe the temporal evolution of the absorption efficiency. The effects of the different operating conditions on the NO, NO 2 and NOx absorption performances (A) were investigated. Results revealed in all the cases that A NOx increases when increasing the proportion of more oxidized species in NOx. Without H 2 O 2 A NOx decreases when the HNO 3 concentration of the solution is increased and also with the recycling of the scrubbing liquid, leading to NOx desorption phenomena. When hydrogen peroxide is added to the nitric acid solution the NOx absorption performances are much higher and increase with the initial H 2 O 2 concentration and the HNO 3 concentration. • A NOx increases when increasing the proportion of more oxidized species in NOx. • Without H 2 O 2 , A NOx decreases when the HNO 3 concentration of the solution is increased and also with the recycling of the scrubbing liquid, leading to NOx desorption phenomena. • When H 2 O 2 is added to HNO 3 solution, A NOx is much higher and increases with the initial concentration of H 2 O 2 and HNO 3 .

A Study of the Absorption of Nitrogen Oxides from the Boiler Flue Gases

In the past decade, the number of unsolved ecological problems has been steadily increasing. Among the numerous causes of this situation, the exposure of the environment to industrial waste should be mentioned. For example, enterprises of the fuel and energy industry emit a significant amount of hazardous substances into the atmosphere. Flue gases formed in boiler-houses and at thermal power stations get through flue gas stacks into the upper atmosphere and pollute it. In this work, a method is proposed for adsorption treatment of the flue gases from boilers fired with associated petroleum gas. The chemical composition of the associated petroleum gas of Romashkino oil field, the Republic of Tatarstan, is presented and the practicality of its use is demonstrated. Nitrogen oxides contained in the boiler flue gases result from oxidation of molecular air nitrogen during combustion of the fuel. In order to reduce the adverse effect of hazardous substances on the environment, the flue gases are to be compulsorily cleansed of nitrogen oxides. The use of the sludge resulting from coagulation and liming of natural water during the chemical water treatment at Kazan CHPP-1 as a sorption material is proposed. The chemical composition and technical characteristics of the sludge are presented. The properties of the sludge were studied using a laboratory fixed-sorbent-bed setup. The sorption capacity and water-absorption of the sludge were determined and curves of the kinetic and isothermal dependences of the nitrogen oxide adsorption by the sludge were constructed. The change in the nitrogen- oxide sorption capacity of the sludge depending on the sludge particle size was established. The optimal characteristics of a batch-type fixed-bed absorber were calculated. The results of calculating the economic and ecological effects of introducing the adsorption treatment of flue gases to remove nitrogen oxides for the boiler-house of AO Karpov Chemical Plant are provided.