USE OF UREA FOR REMOVAL OF NO x FROM SPENT ACID AND FROM THE FUMES COMING OUT DURING NITRATION (original) (raw)
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Study on the removal of NO from flue gas by wet scrubbing using NaClO 3
Journal of the Serbian Chemical Society, 2019
In order to remove nitric oxide (NO) from flue gas, from small coal-fired boilers, it is necessary to exploit the cost-effective wet denitration technology. The absorption of NO with sodium chlorate solution was studied. The effects of experimental conditions, such as temperature, NaClO 3 concentration, type of acid, mole ratio of NaClO 3 to hydrogen ions, on NO removal rate were investigated, and the optimal conditions were established. As the effect of temperature on denitration was related to the type of acid used, the temperature required for sulfuric acid was high, and the temperature required for nitric acid was low. The optimal mole ratio between NaClO 3 and the two types of acids was the same. The reaction products were analyzed by ion chromatography. The reacted solution could be recycled after the removal of sodium chloride. The reaction mechanism and the total chemical reaction equation of NaClO 3 denitration were deduced. The thermodynamic derivations showed that this oxidation reaction could proceed spontaneously and the reaction was very thorough. NaClO 3 exhibited high NO removal efficiency and its denitration cost was much lower than sodium chlorite.
IJMER
Abstract: Pongamia pinata methyl ester (PPME) is chosen as alternative fuel for diesel engines. It is renewable and offer potential reduction in CO; HC and smoke emissions due to higher O2 contents in it compared to diesel fuel but higher nitrogen oxides (NOx) emission. Nitrogen oxides (NOx) in the atmosphere cause serious environmental problems, such as photochemical oxidant, acid rain, and global warming. The removal of nitrogen oxides (NOx) from the exhaust of diesel engines is still a very challenging problem even though there have been many studies. Technologies available for NOx reductions either enhance other polluting gas emissions or increase fuel consumption.Injection of aqueous solutions of urea in the tail pipe of a diesel engine fuelled with Pongamia pinata methyl ester (PPME) for the reduction of oxides of nitrogen (NOx) was carried out in a four stroke, single cylinder, water cooled, constant speed diesel engine. Four observations were made for various concentration of urea solution 0%, 10%, 20%, and 30% by weight with different flow rates of urea solution as reductant by fitting Marine Ferromanganese nodule as SCR catalyst which improves the chemical reactions. 64% NOx reduction achieved with the urea flow rate 0.60 lit/hr, 30% concentration of urea solution and marine ferromanganese nodule as SCR.
Selective Non-Catalytic Reduction (SNCR) of nitric oxide has been studied experimentally injecting different concentrations of aqueous urea solution in a pilot-scale diesel fired tunnel furnace, which was set to run at 3-4% excess oxygen level and was producing low ppm of baseline NO x ranged from 65 to 74 ppm within the investigated temperature range. The furnace simulated small-scale combustion systems such as low capacity boilers, hot water heaters, oil heaters etc., where the operating temperatures are usually in the range of about 900 to 1300 K and baseline NO x emission level remains within 100 ppm. One significant aspect of the study is that it employed commercial grade of urea as NO x reducing agent. The test data showed a significant amount of NO x reduction, which was not pronounced by the previous researchers with urea SNCR for this low ppm of NO x. Variation in concentrations of urea solution has effect on NO x reduction characteristics with residence time, injection temperatures and normalized stoichiometric ratio (NSR). At a particular value of NSR, NO x reduction as well as effective temperature window was observed to be affected at different concentrations of urea flow. At an NSR of 3, a maximum of 51 % reduction was observed using 10% aqueous urea solution at 1128 K, while 25% urea solution achieved only a maximum of 26% reduction. Although the NO x reduction and width of the effective temperature window varied significantly with the variation in solution concentration, the peak temperature of the reduction varied trivially.
2005
A pilot-scale investigation with Selective Non-catalytic Reduction (SNCR) of NO x were carried out by employing the aqueous solution of commercial grade ammonia liquor as NO x reducing agent in diesel burning exhaust at 6% excess oxygen and injection temperatures between 923 and 1323 K. The furnace simulated the small-scale combustion systems such as low capacity boilers, water heaters, oil heaters etc., which produce low level of baseline NO x , usually below 100 ppm and where the operating temperatures remain within the investigated temperature range. With 5% aqueous ammonia solution, at a Normalised Stoichiometric Ratio (NSR) of 4, as much as 57% reduction was achieved at an optimum temperature of 1063 K, which is quite significant for the investigated level of baseline NO x . The NO x reduction was observed to increase as the value of NSR increased. The residence time of the reagent has significant effect on the reaction performance, however, most of the reduction occurred within a short range of residence time and after that further increase in residence time showed very insignificant effect. The ammonia slip measurement showed that at optimum temperature and NSR of 4, the slip was about 18 ppm. The investigations demonstrate that commercial grade liquor ammonia is a potential NO x reducing agent, which could be used effectively and safely considering the health hazards.
2005
A pilot-scale investigation with Selective Non-catalytic Reduction (SNCR) of NO x were carried out by employing the aqueous solution of commercial grade ammonia liquor as NO x reducing agent in diesel burning exhaust at 6% excess oxygen and injection temperatures between 923 and 1323 K. The furnace simulated the small-scale combustion systems such as low capacity boilers, water heaters, oil heaters etc., which produce low level of baseline NO x , usually below 100 ppm and where the operating temperatures remain within the investigated temperature range. With 5% aqueous ammonia solution, at a Normalised Stoichiometric Ratio (NSR) of 4, as much as 57% reduction was achieved at an optimum temperature of 1063 K, which is quite significant for the investigated level of baseline NO x . The NO x reduction was observed to increase as the value of NSR increased. The residence time of the reagent has significant effect on the reaction performance, however, most of the reduction occurred within a short range of residence time and after that further increase in residence time showed very insignificant effect. The ammonia slip measurement showed that at optimum temperature and NSR of 4, the slip was about 18 ppm. The investigations demonstrate that commercial grade liquor ammonia is a potential NO x reducing agent, which could be used effectively and safely considering the health hazards.
A Review of Emission Control by Urea and Ammonia Solution in Diesel Engine
2018
Emission control is one of the biggest challenges in today’s automobiles and for various industries. The selective catalyst reduction (SCR) Is very expensive and hence it can't work for lower duty vehicle as well as in industry. The present investigation deals with the reduction of NOx, SO2, CO, CO2, particulate matter with urea and ammonia solution in a diesel engine. The most harmful pollutants human health and global warming are an oxide of nitrogen. The world is facing tremendous challenges due to increases in greenhouse gas emissions (mainly carbon dioxide), which causes a major global warming problem. Emissions of nitrogen oxides (NOx) Contribute seriously air pollution, the NOx react with moisture in the air to form nitric acid this is a major environmental problem, contributing to soil and water acidification in sensitive areas. In theater treatment method, urea solution sprays either exhaust reach at a temperature of 300°C to 450°C. The area starts to rot and for ammoni...
Study on Characteristics in the Removal Process of
2013
Removal of ammonia nitrogen and nitrate nitrogen by an heterotrophic nitrification-aerobic denitrification strain is an economical and effective method. In this article, a kind of heterotrophic nitrification-aerobic denitrification strain which has aerobic denitrification and heterotrophic nitrification ability was selected, and then was identified as rhodococcus sp. by 16S rRNA sequencing analysis and morphological observation. After that, carbon source utilization and nitrificationdenitrification activity of this strain in different C/N, initial nitrogen concentration were studied. In addition, the assimilation and denitrification activities of ammonia and nitrate were also researched under the condition of nitrate and ammonia coexisted in the solution. The results show that the strain can grow in sodium acetate, glucose, sodium succinate and sodium citrate solutions, and it can not survive in sodium oxalate, sucrose and soluble starch solutions. Initial concentration and C/N were important for nitrogen removal rate. This strain can completely remove nitrate/ammonia when nitrate/ammonia concentration was lower than 15 mg•l-1 /80 mg•l-1. the C/N of 10 and of 12 were the optimum C/N ratio in the nitrate and ammonia removal process respectively. pH value rose up sharply in the denitrification process and it increased relatively slowly in the nitrification process, which shows that pH is one of the most important factor inhibiting the denitrification removal process. Nitrite concentration was much higher in denitrification process than in nitrification process. In addition, this strain gave priority to utilizing ammonia as nitrogen source when ammonia and nitrate coexisted in the solution.
International Journal of Engineering Research and Technology (IJERT), 2013
https://www.ijert.org/reduction-of-nox-emission-by-urea-injection-and-marine-ferromanganese-nodule-as-scr-of-diesel-engine https://www.ijert.org/research/reduction-of-nox-emission-by-urea-injection-and-marine-ferromanganese-nodule-as-scr-of-diesel-engine-IJERTV2IS1272.pdf Today tail pipe emission control has become one of the most important challenges in internal combustion engines. Oxides of nitrogen (NOx) are one of the major hazardous pollutants that come out from diesel engines tail pipe emission. Oxides of nitrogen (NOx) in the atmosphere cause serious environmental problems, such as photochemical oxidant, acid rain, and global warming. There are various techniques existing for NOx control but each technique has its own advantages and disadvantages. At present, there is no single optimal technique that can control NOx without causing other side effects. Technologies available for NOx reductions either increase other polluting gas emissions or increase fuel consumption. Injection of aqueous solutions of urea in the tail pipe of a diesel engine for the reduction of oxides of nitrogen (NOx) was carried out in a four stroke, single cylinder, water cooled, constant speed diesel engine. Four observations were made for the exhaust emission NOx analysis of concentration of urea solution 0%, 10%, 20%, and 30% by weight with different flow rates of urea solution as reductant by fitting Marine Ferromanganese nodule as SCR catalyst. It was observed that 64% of NOx reduction achieved..
Selection of reactive solvent for pollution abatement of NOx
Gas Separation & Purification, 1990
Absorption of NO by liquid absorbents is an important process for pollution abatement. Acritical review has been presented for the various reactive solvents recommended for the absorption of NO. A mathematical model has been developed for sizing of packed columns and bubble columns for the absorption of NO. The dimensions of the equipment have been found for 10 reactive solvents and over a wide range of liquid and gas velocities. Several liquid absorbents, namely FeS04/H2S04, Fe(ll)EDTA, KMnO,/NaOH, and urea have been considered. A procedure has been developed forthe selection of the most economic system for the absorption of NO. Economic analysis was done for the various systems based on fixed and variable costs, materials of construction and additional cost for the regeneration of chemicals and recovery of NO gas.