Natural gas regeneration of carbonate melts following SO₂ capture from non-ferrous smelter emissions

Abstract

a Sulfur emission in the form of SO 2 in flue gases is the one of the most serious atmospheric pollutants associated with coal combustion and non-ferrous metal production. The carbonate eutectic method for removing SO 2 from flue gases at 723-923 K was initially proposed in the 1970's but despite its great efficiency (SO 2 concentration in the flue gas after purification reached 0.003 vol%) it could not be implemented by industry due to the complexity of the carbonate melt regeneration stage. Earlier we proposed a method suited to coal-firing power stations where the melt was regenerated using CO as a reducing agent. However, most metallurgical plants do not use coal and therefore lack a large source of CO. Here we propose a method for removing sulfur from the carbonate eutectic melt by purging it with natural gas or a natural gas/air mixture, which are available in the vast majority of metallurgical plants. This reaction leads to the reduction of sulfate to H 2 S gas that leaves the melt. The experiments we conducted show that nearly complete sulfur removal from the melt is possible at 823 K and that the reaction rate is sufficiently high for a large scale process. The proposed modifications provide solutions to two major problems previously encountered: (i) high temperature corrosion of the reaction cell can be avoided, since a stainless steel cell with high chromium content is stable with respect to the carbonate eutectic melt at 823 K, and (ii) removal of sulfur in the form of H 2 S provides considerable freedom in choosing the final industrially useful product: either sulfuric acid, using H 2 S dry combustion, or elemental sulfur via the Claus process. One can foresee that this carbonate melt-based SO 2 removal technique may become a practical and economically attractive method for limiting sulfur emission to the atmosphere from non-ferrous metallurgical processing plants.

Supramolecular Luminescent Sensors

“…Oxygen detection is complicated by the fact that oxygen itself has limited spectroscopic signals, and therefore oxygen sensors often rely on detecting oxygen-induced reaction products . Multiple instances of oxygen detection using supramolecular chemosensors have been reported, including the use of a terbium-based macrocyclic host and several fluorescent conjugated polymers. , Hydrogen sulfide is a poison, an olfactory irritant, and a serious atmospheric pollutant that is produced as an industrial byproduct . It is also a natural gas and crude oil contaminant that, in concentrations greater than 2%, can lead to a faster combustion of these fuel sources .…”

“…936,937 Hydrogen sulfide is a poison, 938 an olfactory irritant, 923 and a serious atmospheric pollutant that is produced as an industrial byproduct. 939 It is also a natural gas and crude oil contaminant that, in concentrations greater than 2%, can lead to a faster combustion of these fuel sources. 938 Fluorescent macrocycle, 940,941 polymer, 942 and nanocluster 923 hosts have been used for H 2 S detection in solution 923 and in vivo.…”

Semi-industrial technology tests of the sanitary cleaning of metallurgical enterprises waste gases from sulfur and nitrogen oxides

“…Gibbs energy for the reactions of the K 2 CO 3 with NO 2 and NO (reactions 1 and 2 from Table 1) is -(40-80) kJ/mole, within a wide temperature range, including the range of interest 673-873K, thereby predicting rapid scrubbing of the NO 2 and NO by a eutectic carbonate melt from the flue gases. In our previous works [11][12], we showed that potassium carbonate is the main reagent for sulfur capturing from flue gases. The Gibbs energy for the regeneration reactions of the KNO 2 with natural gas (reactions 3 and 4 from Table 1) is -(500-550) kJ/mole, thereby predicting rapid extraction of the nitrogen from the eutectic carbonate melt and its regeneration.…”

“…In previous reports from our group (11,12), we presented the results of thermodynamic calculations for the sul fur scrubbing by a carbonate melt and regeneration of the carbonate melt with CH 4 . Under scrubbing-rege ne ration process conditions, the Gibbs energy of the reactions of the sulfur scrub bing and melt regeneration is strong ly negative.…”

“…An alternative method, based on scrubbing SO 2 from flue gas at 450-650 °C with a carbonate eutectic melt (Na 2 CO 3 -K 2 CO 3 -Li 2 CO 3 ), was initially proposed in the 1970s, but despite its efficiency in converting SO 2 to sulfates, it could not be commercially implemented due to the technical complexity of the removal of the sulfates at the melt regeneration stage. Earlier we demonstrated on a laboratory scale (~0.3-0.5 l melt) a relatively simple procedure for regenerating the postscrubbing carbonate eutectic melt via purging with natural gas [11]:…”