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Show Influence of Additives on Particular Matter from Heavy Fuel Oil Combustion in a Swirling Flame American Flame Research Committee Annual Meeting Salt Lake City, Utah, September 17-19, 2018 Xinyan Pei1,*, Long Jiang1, Chaoqin Chen1, Saumitra Saxena1, William L. Roberts1 1. Clean Combustion Research Center, King Abdullah University of Science and Technology, Saudi Arabia; * Corresponding Author: Xinyan Pei; xinyan.pei@kaust.edu.sa Heavy fuel oil (HFO) is an economical alternative fuel for power generation due to its low production cost and high energy density. However, incomplete combustion usually takes place because of the presence of long-chain petroleum molecules which also result in high emissions levels. Thus, the novel burner used in the study utilizes a high swirl stabilized turbulent jet flame that has been stabilized to efficiently combust HFO with high residence time and mixture ratio between fuel and air. HFO contains primary contaminants, such as Vanadium (V), Nickel (Ni), and sulfur (about 3.0 wt%), results in corrosion of metal surfaces both near the combustion areas and beyond as well as hard slag deposits. In addition, the formation of SO3 (g) is mainly catalyzed by vanadium pentoxide. To reduce the deterioration effects of corrosion, highly Mg-based fuel oil additive has been tested in magnesium-vanadium weight ratio of 1:1. The present study is to exam the effect of HFO additives on the combustion performance by HFO combustion experiments without and with additives under swirling flame condition, especially on solid particle emissions. Moreover, the particulate matter was analyzed by SEM-EDS and TEM to characterize their morphology. The corrosion effect of the solid particles was evaluated by the PH meter at the cooling end. Keywords: heavy fuel oil, swirling flame combustion, Mg-based additives, particulate matter 1. Introduction HFO contains large significant amounts of fuel-bound nitrogen and sulfur which form NOX and SOX respectively during combustion which can cause leading to undesirable pollution1. Cooling end corrosion is associated with the formation of sulphuric acid from the combustion of the sulfur content of HFO2-5. The asphaltene content and carbon residues are also very high which cause cenosphere and coke formation during the combustion process6. Additionally, the trace metals like vanadium are present in substantial quantities leading to hot corrosion of heat transfer surfaces and other components of a typical boiler7-10. In view of these aspects, highly Mg-based fuel oil additive has been tested in magnesium-vanadium weight ratio of 3:1 in this study. The investigation has been conducted to examine the effect of HFO additives on the particulate matter by comparing HFO combustion experiments without and with additives under the swirling flame condition. 2. Experimental method In this study, the HFO sample from Shoaiba power plant in Saudi Arabia was used in this study. Basic compositional data of HFO sample were analyzed using Optima 8300 ICP-OES spectrometer (PERKINELMER, INC.) shown in Table 1. Commercial Highly Mg-based fuel oil additive was applied in Magnesium (Mg)-Vanadium (V) and Nickel (Ni) ratio of 1:1 in mass in the experiment. Fig. 1 shows the HFO spray combustion chamber where a high-swirl stabilized turbulent spray flame was employed to combust the HFO. The detailed constitution and sub-systems are also provided in Fig. 1, which can be divided mainly into: a) fuel supply system, b) spray characteristics measurement system and, c) swirling flame combustion system. Given in Table 2, the swirling flame experiment condition was kept 1 constant in the normal fuel and additive fuel tests with the same swirling number of 19.2 and the global equivalence ratio of 0.91. The stable flame combustion duration was selected to be 10 min. All the parameters measurement and particles collection were under stable combustion condition and all within in 10 min. Table 1 Heavy Fuel Oil Properties. Elements Values Carbon (C) Hydrogen(H) Sulfur (S) Nitrogen(N) Oxygen(O) Ash Asphaltenes Vanadium(V) Nickel(Ni) Sodium(Na) Zinc(Zn) Lead(Pb) Potassium(K) Units 84.2 11 3.68 0.2 <5.0 <0.1 8.2 38.5 20.7 24.1 0.59 <5.0 <5.0 Mass% Mass% Mass% Mass% Mass% Mass% Mass% mg/kg mg/kg mg/kg mg/kg mg/kg mg/kg Fig. 1. The swirling flame experimental system. Table 2 Swirling flame experiment condition. Tangent air (SLPM) Atomizing air (SLPM) Axial air(SLPM) HFO(ml/min) Flow rate 150 Temperature (oC) 600 15 5 15 150 300 150 2 3. Results and discussion In Fig. 2, the deposition rate was calculated by the weight of the particles collected from the filter in the normal HFO and HFO with additives experiments within 10min. The deposition accumulation rate decreases by 39.8% with additives adding in the fuel. In Fig. 3, the PH value of the soli1d particles was measured by the amount of 1g solid particle sample with 30 ml of deionized water from the two different fuel experiments. The PH value has a 32% increase with additives. The morphological analysis of the solid particles was conducted in Fig. 4. The SEM measurement shows two different types of particles. One from the normal HFO appears to be the typical cenosphere. The sample from the fuel with additives is flocculent distribution and further analyzed by the TEM. The TEM measurement result shows the particles from additive fuel experiment are soot, which means an improvement in the solid particle emission. 200 Deposition Rate (mg/min) 180 160 140 120 100 80 60 40 20 0 HFO HFO+Additives Fig. 2 Comparison of the deposition rate between normal HFO and HFO with additives. 7.0 6.5 6.0 5.5 5.0 PH Value 4.5 4.0 3.5 3.0 2.5 2.0 1.5 1.0 0.5 0.0 HFO HFO+Additives Fig. 3 Comparison of the PH value of the solid particles from normal HFO and HFO with additives. 3 a. SEM-HFO particles b. SEM-HFO with additives c. TEM-HFO with additives particles particles Fig. 4 Morphology comparison of particles emission from normal HFO and HFO with additives. 4. Conclusion The experimental investigation has been conducted to examine the effect of HFO additives on the solid particles emissions by HFO combustion experiments without and with additives under the swirling flame condition in a pilot-scale burner. In the swirling flame combustion experiment, when the additives adding to the HFO fuel, the deposition rate decreased by 39.8%, the PH value of the solid particles has a 32% increase, and the morphology of the solid particles was changed from the typical cenosphere to be soot. Conclusions can be drawn from the above results that Mg-based additives have some positive effects on the solid particles emission during HFO combustion. Acknowledgment This research presented in this paper was supported by the Clean Combustion Research Center (CCRC) at King Abdullah University of Science and Technology (KAUST). Reference 1. Ballester, J. M.; Fueyo, N.; Dopazo, C., Combustion characteristics of heavy oil-water emulsions. Fuel 1996, 75, (6), 695-705. 2. Urban, D. L.; Huey, S. P. C.; Dryer, F. L., Evaluation of the coke formation potential of residual fuel oils. Pro. Combust. Inst. 1992, 24, (1), 1357-1364. 3. 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