• Korean Chemical Engineering Research
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• v.48 no.2
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• pp.253-258
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• 2010

In the field of the $CO_2$ absorption process using aqueous ammonia, the effects of regeneration pressure and temperature on $CO_2$ absorption performances of the aqueous ammonia were investigated. The absorbents were prepared by dissolving ammonium carbonate solid in water to grant the resulted solution 0.5 $CO_2$ loading ($mol\;CO_2/mol\;NH_3$) and various ammonia concentration (14, 20, 26 and 32 wt%). As-prepared absorbents were regenerated at high pressure and temperature (over $120^{\circ}C$ and 6 bar) before the absorption test. The absorption test was carried out by injecting the simulated gas that contains 12 vol% of $CO_2$ into a bubbling reactor. The introduction of 26 wt% of the ammonia concentration for $CO_2$ absorption test resulted in the higher absorption capacities than other experimental conditions. In particular, when the absorbents with 26 wt% of the ammonia were regenerated at $150^{\circ}C$ and 14 bar, the highest absorption capacity, $45ml\;CO_2/g$, was obtained. According to the analysis of absorbents using acid-base titration, the ammonia loss during the regeneration of the absorbents with a fixed ammonia concentration decreased as the regeneration pressure increased, while it increased as the regeneration temperature increased. In the condition of fixed regeneration pressure and temperature, as expected, the ammonia loss increased as the ammonia concentration increased. The measured $CO_2$ loadings and ammonia concentrations of absorbents were compared to the values calculated by Electrolyte NRTL model in Aspen Plus.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.13 no.5
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• pp.451-457
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• 2000

Experimental investigations on the effect of two kinds of additives ; aqueous NaOH solution and ammonia(NH$_3$) for removal of NOx and SO$_2$ simultaneously by corona discharge were carried out. The simulated combustion flue gas was[NO(0.02[%])-SO$_2$(0.08[%])-$CO_2$-Air-$N_2$] Volume percentage of aqueous NaOH solution used was 20[%] and $N_2$flow rate was 2.5[$\ell$/min] for bubbling aqueous NaOH solution Ammonia gas(14.81[%]) balanced by argon was diluted by air. NH$_3$ molecular ratios(MR) based on [NH$_3$] and [NO+SO$_2$] were 1, 1.5 and 2.5 The vapour of aqueous NaOH solution and NH$_3$was introduced to the main simulated combustion flue gas duct through injection systems which were located at downstream of corona discharge reactor. NOx(NO+NO$_2$) removal rate by injecting the vapour of aqueous NaOH solution was much better than that by injecting NH$_3$however SO$_2$removal rate by injecting NH$_3$was much better than that by injecting the vapour of aqueous NaOH SO$_2$removal rate slightly increased with increasing applied voltage. When the vapour of aqueous NaOH solution and NH$_3$were simultaneously injection NOx and SO$_2$ removal rate were significantly increased.

• Journal of Energy Engineering
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• v.10 no.4
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• pp.357-362
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• 2001

A bench type ammonia-water absorber heat exchange cycle was tested by varying the system charging concentration, refrigerating valve opening and weak solution flow rate. It was observed that the cooling capacity was increased as the system charging concentration was increased. Optimum system charging concentration was found for the coolong capacity of the system. The opening rate of refrigerant expansion valve had a direct influence on the refrigerant sub-cooling at the condenser outlet. Optimum sub-cooling was found to be 0~4$^{\circ}C$. As the weak solution flow rate increased the concentration of strong solution and the evaporating pressure decreased. There existed a optimum weak solution flow rate which maximized the cooling capacity and COP.

• Korean Journal of Air-Conditioning and Refrigeration Engineering
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• v.11 no.4
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• pp.431-439
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• 1999

A generator-GAX combined rectification system of an ammonia absorption heat pump was investigated to get the optimum design values. The mass and heat transfer phenomena of the rectification system were analysed. The number of column plates, equilibrium temperature of solution on each plate and flow rates of solution and vapor generated were predicted. The characteristics of mass and heat transfer of the generator-GAX combined rectification system, i.e. concentration difference of leaving solution and vapor on each column plate, were found to be mainly governed by the pressure of generator, reflex ratio and temperature difference of analyser coolant. The number of rectification column plates for each different pressure in generator was obtained. The optimum locations for installing the feeder from solution-cooled absorber and GAX desorber in generator were predicted. The improvement of COP was followed by the increase of the rectifier efficiency and the number of column plate, and the decrease of reflex ratio.

• Korean Journal of Air-Conditioning and Refrigeration Engineering
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• v.15 no.10
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• pp.828-834
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• 2003

A diffusion absorption refrigerator is a heat-generated refrigeration system. It uses a three-component working fluid consisting of the refrigerant (ammonia), the absorbent (water) and the auxiliary gas (hydrogen or helium). In this study, experimental investigations have been carried out to examine the effects of charging conditions of working fluids on the evaporating temperature for diffusion absorption refrigerator. Experimental parameters considered in the present experiments are charging concentration, solution charge and system pressure determined by auxiliary gas charged. As a result, in the charging condition of 35% of concentration and 20 kg$_{f}$cm$^2$ of system pressure, the system has the lowest evaporating temperature. It was found that there exists a minimum value of solution charge for the operation of diffusion absorption refrigerator.r.

• Korean Chemical Engineering Research
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• v.51 no.5
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• pp.568-574
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• 2013

A semi-pilot biofilter packed with media with immobilized Thiobacillus sp. IW and return sludge, was operated under various operating conditions in order to treat malodorous waste air containing both hydrogen sulfide and ammonia which are major air pollutants emitted from composting factories and many publicly owned treatment works (POTW). At the incipient and middle stages of a semi-pilot biofilter operation, the hydrogen sulfide-removal efficiency behaves regardless of an inlet-load of ammonia. However, the ammonia-removal efficiency decreased as an inlet-load of hydrogen sulfide increased. Nevertheless, at the final stage of the semi-pilot biofilter operation, the ammonia-removal efficiency was not affected by the increase of hydrogen sulfide-inlet load. It is attributed to that a serious acidification of semi-pilot biofilter-media did not occur due to continuous injection of buffer solution at the final stage of the semi-pilot biofilter operation. When both hydrogen sulfide and ammonia contained in malodorous waste air were treated simultaneously by semi-pilot biofilter, the maximum elimination capacities of hydrogen sulfide and ammonia turned out to be ca. 58 and $30g/m^3/h$, respectively. These maximum elimination capacities were estimated to be ca. 39 and 46% less than those for lab-scaled biofilter-separate elimination of hydrogen sulfide and ammonia, respectively. Thus, for the simultaneous biofilter-treatment of hydrogen sulfide and ammonia, the maximum elimination capacity of ammonia decreased by 7% more than that of hydrogen sulfide.

• Journal of the Korean Applied Science and Technology
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• v.32 no.3
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• pp.372-376
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• 2015

The experiment was performed using the cleaning precipitator To investigate the absorption efficiency of the $SO_X/NO_X$ of the aqueous ammonia solution. Concentration of the cleaning liquid is 0.1, 0.5, and 1.0% with increasing absorption efficiency has improved. However, the reaction shown only a difference in time. Absorption efficiency has improved in accordance with the gas residence time. When the direction of the same gas and the cleaning liquid is determined that there is the effect of increasing the residence time. The relative impact of $SO_X$ and $NO_X$ is this likely to react slower than $SO_X/NO_X$. The yield is determined to require adjustment of the cleaning dust collector according to the concentration of the next gas.

• Resources Recycling
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• v.12 no.2
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• pp.36-44
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• 2003

The present work relates to the recovery of dissolved Mo from spent mandrel dissolving acid solution by injecting ammonia gas. In order to optimize the process parameters for high yield and high purity of recovered Mo products, a bench scale and a pilot scale experiments were carried out. As a result, more than 99.5% of Mo in spent acid was recovered in the form of ammonium molybdate(4MoO$_3$.$2NH_3$.$H_2$O). The purity of Mo products recovered was higher than 99.5%. In addition, the mother liquor, residual solution after precipitation and filtration of ammonium molybdate solid particles, could be utilized as fertilizers.

• Journal of ILASS-Korea
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• v.25 no.4
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• pp.196-203
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• 2020

Nowadays, urea SCR technology is considered as the most effective NOx reduction technology of diesel engine. However, low NOx conversion efficiency under low temperature conditions is one of its problems to be solved. This is because injection of UWS (Urea Water Solution) is impossible under such a low temperature condition due to the problem of insufficient of urea decomposition and urea deposits. In several previous studies, it has been reported that appropriate control of the amount of ammonia adsorbed on SCR catalyst can improve the NOx conversion efficiency under low temperature conditions. In this study, we tried to find out how much the NOx conversion efficiency increases with respect to the amount of ammonia adsorbed on the catalyst, and what the temperature conditions that the ammonia slip occurs. This study shows the results of 8 times repeated WHTC test with a diesel engine, in which UWS was injected with NH3/NOx mole ratio of '1'. Through this study, it was found that 13% of the NOx conversion efficiency of WHTC increased while the θ (ammonia adsorption rate) increased from "0%" to "22%". In addition, it is found that in cases of high θ value, the significant improvement of NOx conversion efficiency at low temperatures presented during the beginning period of WHTC and at high temperature and transient conditions presented during last part of WHTC test. The NH3 slip occurring condition was 250℃ of catalyst temperature and 10% of θ, and the amount of NH3 slip increased as the temperature and θ are increased.

• Bulletin of the Korean Chemical Society
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• v.6 no.6
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• pp.329-333
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• 1985

A procedure for the preparation of peptizable pseudoboehmite has been described in detail based upon a process of neutralization of an aqueous aluminum sulfate or chloride solution with aqueous ammonia. In order to obtain peptizable pseudoboehmite products, carefully controlled conditions were required in the whole processes of neutralization, aging, washing, and drying. The optimum conditions experimentally found are the following. The aluminum salt solution is neutralized with aqueous ammonia until the final pH of the solution reaches 10.0 to 10.8 or 9.0 to 9.3 for the sulfate of chloride, respectively. The alumina gel formed is subjected to aging at $80^{\circ}C for about 3 hours and washed with water more than 5 times to reduce the residual sulfate or chloride ion in the final products to less than 4%. The pseudoboehmite gel thus obtained should be dried oven at 80 to $100^{\circ}C for a few to several hours depending on the selected temperatures.