Sulphur inputs

Hertel O, Skj0th CA, Frohn LM, Vignati E, Frydendall J, de Leeuw G, Schwarz U, Reis S (2002) Assessment of the atmospheric nitrogen and sulphur inputs into the North Sea using a Lagrangian model. Phys Chem Earth 27 1507-1515... 

The amount of sulphur entering the oceans in river runoff has probably more than doubled due to human activities (compare the fluxes in Fig. 7.17a b). This has been caused in part by sulphur-rich wastewaters and agricultural fertilizers entering river and groundwaters and thence the sea, although another major factor is sulphur deposited directly into surface waters from the atmos-ph ere. The combined (atmospheric and runoff) effects of enhanced sulphur inputs to seawater cause an increase of sulphur (as SO)- in the oceans) of only about 10 5% per annum. This estimate is probably an upper limit, since it assumes that removal of seawater sulphur into ocean sediments (see Section 6.4.6) remains as previously and has not increased following the enhanced inputs from the atmosphere and rivers. 

To ensure that adequate sulphur is available, it is becoming more essential to monitor sulphur inputs and outputs and to construct sulphur balances and cycling models that will simulate the cycle of this nutrient... 

This input to design refers to the long-term stability of the raw material sources for the plant. It is only of importance where the raw materials can or do contain impurities which can have profound effects on the corrosivity of the process. Just as the design should cater not only for the norm of operation but for the extremes, so it is pertinent to question the assumptions made about raw material purity. Crude oil (where HjS, mercaptan sulphur and napthenic acid contents determine the corrosivity of the distillation process) and phosphate rock (chloride, silica and fluoride determine the corrosivity of phosphoric acid) are very pertinent examples. Thus, crude-oil units intended to process low-sulphur crudes , and therefore designed on a basis of carbon-steel equipment, experience serious corrosion problems when only higher sulphur crudes are economically available and must be processed. 

The background for the development of VK69 was a need for reduction of S02 emissions from double-absorption plants by installing a more active catalyst at low temperature downstream from the intermediate absorption tower. Clearly, the catalytic solution should be more competitive than the alternatives, e.g. tail gas scrubbing or triple-absorption layout, in terms of capital and operating costs. In the following, the required technical performance of the catalyst with respect to S02 oxidation activity, mechanical strength and pressure drop is discussed, and input from the literature and from practical experience in the field is presented. Reviews of the extensive literature published on sulphuric acid catalysts can be found in [2-5],... 

First value input of sulphur section second value after initial dehydration of aqueous sulphuric acid. 

Another notable element of the cost increases is the inclusion in the Shaw flow sheets of subsystems for hydrogen product purification and for feed water purification. For S-I and to a lesser extent for HyS, concern with the carry-over of sulphur to the product necessitated a significantly costly purification subsystem on the product end of the cycle. For HTSE, the issue is uncertainty in the purity of input steam and effects on the electrolysis cells, and so a large feedwater purification subsystem impacts the overall capital cost. In the earlier evaluations these subsystems were not considered significant enough to include. 

Input and output enthalpies of various streams across each section for a 100 TPD DC-DA sulphuric acid plant uith 10% sulphur dioxide feed to converter, 99.87b conversion efficiency and 99.9/5 absorption efficiency are shoun in Table I. 

The available energy flou through five major sections of sulphuric acid plant is given in figure 2. The major inputs to this system are sulphur and pouer, with demineralised (DM) water uet air, process water and cooling water from environment. The useful outputs from the system are sulphuric acid and steam. Losses to environment include heat losses from various equipments blowdown water steam from deaerator vent warm water and stack gas. 

The reaction proceeds, with charge or power input, from left to right. As there is no valency change between Na2S4 and Na2S2, the polymerised sulphur is referred to as zero-valent . 

I do not want to go into Professor Liberti s paper — he will do this in more detail — but it is a fact we have a very great input of acids, not only sulphuric acid but also nitric acid. We are asking you as chemists could you... 

Almost all thermochemical biomass conversion processes can be considered and thus analysed as a black box with a feedstock input and an energy output (either thermal or electrical). Useful co-products will arise in the operation of the process (eg sulphur, acetic acid, methanol even food flavouring ) from which revenue may be earned. Relatively useless by-products (eg ash, frit and other emissions to air, land and water) which arise may incur a cost in their disposal if a market for their use cannot be found. 

The Archaean atmosphere-ocean system was probably less oxic than today, but supply of oxidant would have occurred nevertheless as, in an Archaean C02-based atmosphere, volcanic sulphur and nitrogen sources would have provided SO t and NO, or precursors that would have been oxidized in the atmosphere to and NO. Together with nitrogen-fixing by lightning, this would have supplied sulphate and nitrate for use by microbes living in mud that contained picoplankton debris, to sustain mats, possibly of colourless sulphur bacteria. The REE record a distant hydrothermal input, which, depending on water currents, supplied metals and perhaps episodes of reduction. 

In the experiments involved the amount of water from the gas scrubber related to the amount of raw input material was about 0.18 m3/t. The pH-value of the water was mildly alkaline, the chloride concentration was about 290 mg Cl /1 and the total amount of phenols about 23 mg/1. Annealing loss of the scrubber water sediment was 2800 mg/1, and the annealing residue amounted to 8000 mg/1. Sulphur was found mainly in an oxidized form. Results of initial experiments using an apparatus for the determination of the biochemical oxygen demand allowed the conclusion that an undisturbed decomposition of the organic components can take place. 

The deposition flux of sulphur from the atmosphere on to the oceans and land surfaces has increased by approximately 2 5 and 163%, respectively. Although this input has essentially no impact on the chemistry of seawater, due to its buffer capacity and the large amount of sulphate (SO -) it contains (see... 

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