Equilibria in Limestone-Based FGD Process:  Magnesium Addition

Michalski, J.

doi:10.1021/ie050160p

Cited by 7 publications

(6 citation statements)

References 6 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…Flue gas desulfurization (FGD) is recognized as the most effective technology for removing SO 2 emissions derived from fossil-fuel combustion and metallurgical and oil-refining industries. − In turn, wet FGD using Ca-based slurries as absorbents (limestone and lime) is the most widely applied method because of the abundance of the components, the reliability of the system, and the well-known chemistry that takes place during the process. − The literature has already highlighted the virtues of substituting lime and limestone with magnesium compounds because of the greater solubility of magnesium sulfite/sulfate products with respect to their calcium equivalents. − This fact allows maintaining an alkaline pH during longer periods of desulfurization and hence results in an improved SO 2 removal efficiency. However, although this enhancement effect is widely known, the higher costs of magnesium compounds has resulted in only slight additions (3–8 wt %) to the Ca-based conventional methods, modifying them to become magnesium-enhanced limestone/lime processes. , Fostered by the Industrial Emissions Directive of the European Union (2010/75/EU) and the 2013 Best Available Techniques (BAT) reference documents, the potential reutilization of residues as desulfurization agents have been the topic of several researches. ,, In this regard, the authors have reported that the reutilization of several byproducts from the calcination of natural magnesite is a feasible technology that can attain a 100% removal efficiency by fully making profit of the magnesium enhancement effect . By this manner, a sustainable closed-loop processin which the byproducts from the SO 2 emission process itself are reused as absorbentscould be adapted to the overall production process, following the guidelines of legislation and economic optimization.…”

Section: Introductionmentioning

confidence: 99%

“…However, although this enhancement effect is widely known, the higher costs of magnesium compounds has resulted in only slight additions (3−8 wt %) to the Ca-based conventional methods, modifying them to become magnesium-enhanced limestone/ lime processes. 12,13 Fostered by the Industrial Emissions Directive of the European Union (2010/75/EU) and the 2013 Best Available Techniques (BAT) reference documents, the potential reutilization of residues as desulfurization agents have been the topic of several researches. 10,11,14 In this regard, the authors have reported that the reutilization of several byproducts from the calcination of natural magnesite is a feasible technology that can attain a 100% removal efficiency by fully making profit of the magnesium enhancement effect.…”

Section: Introductionmentioning

confidence: 99%

See 1 more Smart Citation

Desulfurization Performance of MgO Byproducts as a Function of Particle Size

et al. 2016

View full text Add to dashboard Cite

The reuse of MgO byproducts as SO2 absorbents in a sustainable closed-loop process follows the guidelines of legislation and economic optimization. The aim of the present study was to enhance the desulfurization performance of an MgO byproduct by sieving to different size fractions and relating them with their reactivity and physical characteristics. The byproduct presented a rather irregular size distribution, with Mg presented as MgO, Mg(OH)2, and MgCO3 and Ca as CaO, Ca(OH)2, and CaSO4. The time of saturation (t S) was used for evaluating the desulfurization performance of each fraction with 100% removal efficiency. Thus, two different conditions for enhancing the desulfurization performance were described. A chemically established condition where the sorption capacity is improved by adding more solids and a second one dependent only on physical parameters. Accordingly, sieving to the finest size fraction could improve the desulfurization capacity close to an optimum value (2.9 kg of solids can totally neutralize 1 m3 of SO2). Taking into account that the average grinding cost to a particle size below 0.075 mm is 11.54 euro per ton, adding an extra operational unit prior to desulfurization might be a feasible alternative for attaining 100% removal efficiency. Moreover, CaSO3 and CaCO3 were the main reaction products from desulfurization, which could be reused as construction aggregates.The procedure for finding a valuable methodology for improving the SO2 removal capacity of this kind of byproduct could be extended to other wastes and residues.

show abstract

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Desulfurization Performance of MgO Byproducts as a Function of Particle Size

et al. 2016

View full text Add to dashboard Cite

show abstract

“…At present, the most conventional method to reduce SO 2 emissions is to operate flue gas desulfurization (FGD) devices (Xu 2011), However, FGD operations have many disadvantages, such as high cost, poor byproduct quality, and secondary pollution . For instance, Wet limestone FGD processes are extensively used at point sources which accounts for over 90 % of installed desulfurization capacities in the world (Kikkawa et al 2002), but such process is not environment friendly enough because 1 M CO 2 is released along with 1 M SO 2 adsorption (Gutiérrez Ortiz et al 2006;Michalski 2006). According to the data over 2005-2010, the contribution weight of engineering technology for reduction of SO 2 was 62.71 % (Tursun et al 2015), which means that some cleaner and greener technologies for flue gas desulfurization are of great importance to develop.…”

Section: Introductionmentioning

confidence: 99%

Green SO2 conversion from flue gas by pH variation

Guo

Yang

et al. 2015

Clean Techn Environ Policy

View full text Add to dashboard Cite

Emissions reduction or conversion by clean technologies has always been a mission for environmental protection and sustainable development. A green, electrochemically driven conversion of SO 2 to NaHSO 4 from flue gas by pH variation was conducted. Experiments were carried out to investigate some factors affecting the conversion process, such as O 2 function in flue gas, selected initial pH (pH 0 ) of solution, and CO 2 effects of high concentration. Experimental results revealed that (i) O 2 was essential for SO 2 absorption, since the pH of solution was decreased more effectively than that of flue gas without O 2 . The lowest pH of absorption solution with pouring O 2 was about 3.2, which was benefit to formatting HSO 3 -but hindering absorption of CO 2 . Meanwhile, O 2 from flue gas accelerated the adsorption of SO 2 for its oxidability to change HSO 3 -and SO 3 2-ions into SO 4 2-. (ii) At the conditions of different pH 0 , the minimum absorption efficiency of SO 2 was 89.3 %, corresponding to pH 0 5.0 and 7.0, while maximum value was 100.1 % corresponding to pH 0 6.0, which meant pH 0 6.0 was more appropriate for SO 2 conversion by electrochemistry under the experimental pH 0 range. (iii) The absorption efficiency of CO 2 was at a very low level under conditions of pH 0 5.0, 6.0, and 7.0, whose value of minimum and maximum was 0.07 and 0.19 %. The result showed that high concentration of CO 2 from flue gas had little affection on desulfurization under the experimental pH 0 range, which enable to infer that byproduct of NaHSO 4 is pure enough.

show abstract

“…Numerous studies explore the influence of some specific compounds on SO 2 capture efficiency such as chloride content, , magnesium content, addition of organic additives, − or the influence of a specific limiting step such as limestone reactivity ,− or sulfite oxidation. − …”

Section: Introductionmentioning

confidence: 99%

“…Gypsum precipitation has been experimentally studied, 22,23 and population balances can be used to quantify the complex behavior of crystal nucleation and growth in the suspension. 24 Industrial & Engineering Chemistry Research ARTICLE Numerous studies explore the influence of some specific compounds on SO 2 capture efficiency such as chloride content, 25,26 magnesium content, 27 addition of organic additives, 28À30 or the influence of a specific limiting step such as limestone reactivity 21,31À36 or sulfite oxidation. 37À41 Some other studies focus on the aero-and hydrodynamics of FGD units 42,43 in order to determine pressure drop, gas misdistribution, and droplet coalescence or to link desulfurization efficiency with these phenomena.…”

Section: Introductionmentioning

confidence: 99%

Wet Industrial Flue Gas Desulfurization Unit: Model Development and Validation on Industrial Data

Neveux¹,

Moullec²

2011

Ind. Eng. Chem. Res.

View full text Add to dashboard Cite

A dynamic model representing an industrial flue gas desulfurization (FGD) unit has been developed. The purpose of this model is to anticipate new SO2 emission legislation and to study some industrial issues such as the influence of a NH3 slip (from the selective catalytic reduction (SCR) unit) or fly ashes (from the electrostatic precipitator). Interaction between gas, liquid, and solid phases have been taken into account as well as a detailed liquid chemistry with the main acid–base equilibria and nonideal thermodynamic behavior. All major rate-controlling steps are modeled: limestone dissolution, sulfites oxidation, and precipitation of gypsum. The absorber hydrodynamic is modeled using an Euler–Euler approach to represent countercurrent flow between flue gas and droplets; the oxidation reactor is modeled as a bubble reactor. Fly ash collection and solid handling were also implemented in order to predict the gypsum quality. The model results were successfully compared with industrial data acquired in the Cordemais (France) coal-fired power plant. The average deviation between model results and industrial data is 5%. Most of the differences between model and experiment are probably due to the lack of a precise and actualized liquid composition to initialize the model. The transient response of the model represents correctly the behavior encounter in the Cordemais power plant. Some detailed transient response experiments are needed in order to definitely validate the transient response of the model. The main hypotheses and parameters of the model were discussed and tested in order to quantify their respective influence. It appears that the aerodynamic hypothesis in the gas inlet zone and the droplet size estimation were affecting very significantly the model results. None of the rate-based submodel can be neglected: liquid and gas transfer, absorption enhancement factor, sulfite oxidation, and limestone dissolution. The expression of SO2 absorption enhancement factor is crucial for the good representation of SO2 absorption; our simplified enhancement factor gives good results in terms of being representative of the holding tank pH.

show abstract

Equilibria in Limestone-Based FGD Process: Magnesium Addition

Cited by 7 publications

References 6 publications

Desulfurization Performance of MgO Byproducts as a Function of Particle Size

Desulfurization Performance of MgO Byproducts as a Function of Particle Size

Green SO2 conversion from flue gas by pH variation

Wet Industrial Flue Gas Desulfurization Unit: Model Development and Validation on Industrial Data

Contact Info

Product

Resources

About