Enhanced oxidation of MgSO 3 during desulfurization by a novel spray method in magnesium-based seawater exhaust gas clean system

Abstract

The magnesium-based seawater exhaust gas clean system is effective in reducing sulfur dioxide emission from marine diesel engines. Oxidation of the desulfurization by-product, magnesium sulfite (MgSO₃), is required for recycling. However, the oxidation efficiency is generally low in the aeration tank after the desulfurization process, making the tank volume too large for practical use on ocean vessels. In this article, we propose a novel spray oxidation method to enhance the oxidation of MgSO₃ during the desulfurization process. The effects of MgSO₃ content, pH and temperature on the oxidation rate were investigated. The results showed that the spray oxidation rate of MgSO₃ was 1.5 order with respect to the MgSO₃ concentration under both unsaturated and saturated conditions of MgSO₃ solution, which is different from the aeration oxidation researches. The spray oxidation rate decreased with the increase in pH and raised slowly as the temperature increased. The MgSO₃ oxidation mechanism of the spray oxidation method was analyzed and discussed in comparison with the traditional bubble aeration method. The novel spray oxidation method is effective in reducing the cost of the subsequent MgSO₃ aeration oxidation process and the offprint of aeration tanks, thus is promising to be applied on ocean vessels.

Keywords

Magnesium sulfite magnesium sulfate oxidation desulfurization ocean vessel

Get full access to this article

View all access options for this article.

References

Endresen

. Emission from international sea transportation and environmental impact. J Geophys Res 2003; 108(D17): 4560.

IMO Resolution MEPC. Amendments to the annex of the Protocol of 1997 to amend the international convention for the prevention of pollution from marine, 1973, as modified by the protocol of 1978 relating thereto (revised MARPOL Annex VI), 2008, 176(58), http://www.imo.org/en/OurWork/Environment/PollutionPrevention/AirPollution/Documents/176(58).pdf

IMO Resolution MEPC. Guidelines for exhaust gas cleaning systems. Marine Environment Protection Committee, 57/21, Annex 4, 2008, 170(57), http://schonescheepvaart.nl/downloads/regelgeving/doc_1362493348.pdf

Caiazzo

Langella

Miccio

et al . An experimental investigation on seawater SO₂ scrubbing for marine application. Environ Prog Sustain Energy 2013; 32(4): 1179–1186.

Zhu

Tang

Zhang

et al . Marine sulfur oxide emissions control research progress. J Environ Eng 2014; (8): 68–71.

Zhu

Tang

Hao

et al . Magnesium base-seawater desulfurization system for marine flue gas. CN201120040 5654, China 2011.

Yang

. Removal efficiency of magnesium base-seawater desulfurization for marine flue gas. Master’s Dissertation, Dalian Maritime University, Dalian, China, 2011.

IMO. Advice by GESAMP on the interim criteria for discharge of washwater from exhaust gas cleaning systems for removal of sulphur-oxides (59th Session, Agenda Item 4—prevention of air pollution from ships). Marine Environment Protection Committee, 59/4/19, 8 May 2009.

Y-Y

et al . Study on washwater effluent quality discharged by ship exhaust gas DeSO(x) system with magnesium and seawater desulphurisation method. Int J Environ Pollut 2015; 56(1–4): 1–10.

10.

Shen

Guo

Kang

et al . Kinetics and mechanism of sulfite oxidation in the magnesium-based wet flue gas desulfurization process. Ind Eng Chem Res 2012; 51(11): 4192–4198.

11.

Wang

Yuan

et al . Mechanism and kinetics of uncatalyzed oxidation of magnesium sulfite under heterogeneous conditions. Sci Sinica Chim 2010; 40: 1172–1178.

12.

Wang

et al . Oxidation rate of magnesium sulfite catalyzed by cobalt ions. Environ Sci Tech 2014; 48(7): 4145–4152.

13.

Zhu

Hefeng

et al . Experimental investigation of MgSO3 oxidation process by catalysis in the magnesium desulfurization. Catal Today 2015; 258: 70–74.

14.

Vidal

Ollero

. Kinetic study of the oxidation of S (IV) in seawater. Environ Sci Tech 2001; 35(13): 2792–2796.

15.

Gang

. Experimental research on the key technology of flue gas desulfurization with magnesium sulfate recovery. Master’s Thesis, Tsinghua University, China, 2009.

16.

Zhou

. Study on conditions of the oxidation of magnesium sulfite and the device design. Changchun, China: Ji Lin University, 2013.

17.

Shen

. Research on magnesium-based wet flue gas desulfurization technology based on the resources of the product. Shanghai, China: East China University of Science and Technology, 2013.

18.

Wang

et al . Non-catalyzed intrinsic oxidation kinetics of sulfite in wet desulfurization process. Acta Chim Sinica 2007; 65(22): 2618–2622.

19.

Lancia

Musmarra

Pepe

et al . Model of oxygen absorption into calcium sulfite solutions. Chem Eng J 1997; 66: 123–129.

20.

Linek

Vacek

. Chemical engineering use of catalyzed sulfite oxidation kinetics for the determination of mass transfer characteristics of gas–liquid contactors. Chem Eng Sci 1981; 36: 1747–1768.