Ammonia absorption from atmosphere

We can thus conclude that the spring maximum cannot be explained either by the annual variation of source intensity at the Earth s surface or by the variation of the quantity of precipitation. It has been postulated (E. Meszaros, 1974a) that this maximum is due to the oxidation effects of tropospheric ozone, the concentration of which also has a maximum during the spring (see Fig. 13). Ozone oxidizes S02 and N02 in atmospheric liquid water (see Subsection 5.3.2) which leads to the lowering of the pH. The increase in the concentration of hydrogen ions promotes the absorption of ammonia gas from the air, as well as the transformation of insoluble mineral components (e.g. calcium carbonate) into water-soluble materials. If this speculation is correct, this process provides a non-negligible ozone sink in the... 

Copper and its alloys, nickel, zinc, galvanised surfaces and aluminium alloys are all attacked by ammonia. Iron, steel, pure aluminium and stainless steel are suitable for the construction of storage vessels. Ammonia liquor is conveniently handled in mild steel. Bulk storage installations for ammonia liquor must be bunded and at a reasonable distance (depending on size of installation) from dwelling houses and places of public assembly. Ammonia liquor tanks should be bunded by themselves and never in a common bund with any other substance with which ammonia will react. Pumps should be sited within the bund, and the filling connection should terminate just inside the bund wall. Ammonia liquor should be stored in closed tanks to prevent ammonia escaping to the atmosphere and to prevent the absorption of atmospheric carbon dioxide. 

A basic problem for the production of nitric acid from ammonia can be found in [1,7]. However, typically dual processes have become preferred in order to take advantage of the physicochemical principles so that it is possible to enhance the conversion of ammonia oxidation at low pressure and improve the gases absorption downstream at a higher pressure. The problem that we address is presented as follows. The production of HNO3 fro ammonia starts with atmospheric air. The ratio between oxygen and ammonia to be fed to the converter must be 2.11, and the... 

Steam reforming process used in ammonia plants. Natural gas feed. Sulfur absorption on activated carbon secondary reforming high temperature shift catalysts used. Reformer-pressure increasing from atmospheric to 9bar. Plant capacity increasing from 150 tpy to 300 tpy. 

Dual-Pressure Process. Dual-pressure processes have a medium pressure (ca 0.3—0.6 MPa) front end for ammonia oxidation and a high pressure (1.1—1.5 MPa) tail end for absorption. Some older plants still use atmospheric pressure for ammonia conversion. Compared to high monopressure plants, the lower oxidation pressure improves ammonia yield and catalyst performance. Platinum losses are significantiy lower and production mns are extended by a longer catalyst life. Reduced pressure also results in weaker nitric acid condensate from the cooler condenser, which helps to improve absorber performance. Due to the spHt in operating conditions, the dual-pressure process requires a specialized stainless steel NO compressor. 

In a packed column, operating at approximately atmospheric pressure and 295 K, a 10% ammonia-air mixture is scrubbed with water and the concentration of ammonia is reduced to 0.1%. If the whole of the resistance to mass transfer may be regarded as lying within a thin laminar film on the gas side of the gas-liquid interface, derive from first principles an expression for the rate of absorption at any position in the column. At some intermediate point where the ammonia concentration in the gas phase has been reduced to 5%. the partial pressure of ammonia in equilibrium with the aqueous solution is 660 N/nr and the transfer rate is ]0 3 kmol/m2s. What is the thickness of the hypothetical gas film if the diffusivity of ammonia in air is 0.24 cm2/s ... 

Apart from the economic significance of such loss there are potentially adverse effects on the environment arising from acidification of rain and soil. Ammonia may react with hydroxyl radicals in the atmosphere to produce NOx contributing to the acidification of rain (4). Wet and dry deposition of NH3/NH4+ inevitably contributes to soil acidification through their subsequent nitrification. This effect can be accentuated in woodland by absorption of aerosols containing NH4+ within the canopy followed by transport to the soil in stem flow (5). In more extreme cases, NH3 emission from feedlots, pig and poultry... 

According to Strobel (945,946) the upper atmosphere ( > 100 km) photochemistry is dominated by the photolysis of methane. Only below 100 km the atmosphere contains suflicient ammonia to be photochemically important. The photochemically effective wavelengths for NH3 photolysis are in the range from 1600 A, the onset of CH4 absorption, to 2300 A, the onset of NH3 absorption. The photolysis of NH3 has already been discussed (see... 

The necessary starting point for any study of the chemistry of a planetary atmosphere is the dissociation of molecules, which results from the absorption of solar ultraviolet radiation. This atmospheric chemistry must take into account not only the general characteristics of the atmosphere (constitution), but also its particular chemical constituents (composition). The absorption of solar radiation can be attributed to carbon dioxide (C02) for Mars and Venus, to molecular oxygen (02) for the Earth, and to methane (CH4) and ammonia (NH3) for Jupiter and the outer planets. 

Experiments are carried out at atmospheric pressure on the absorption into water of ammonia from a mixture of hydrogen and nitrogen, both of which may be taken as insoluble in the water. For a constant mole fraction of 0.05 of ammonia, it is found that the absorption rate is 25 per cent higher when the molar ratio of hydrogen to nitrogen is changed from 1 1 to 4 1. Is this result consistent with the assumption of a steady-state gas-film controlled process and, if not, what suggestions have you to make to account for the discrepancy ... 

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