Osami Nishida

Characteristics of soot formation and decomposition in turbulent diffusion flames

Profiles of soot concentration together with gas species concentrations and temperature are measured in propane/air turbulent diffusion flames of two typically different air inlet temperatures of 50 and 500 C, paying special attention to the roles of gas temperature on the behavior of soot formation and burnout in the flames. Soot is most likely to be produced in the fuel-rich region just inside the flame front, where unburnt hydrocarbons such as CH/sub 4/, C/sub 2/H/sub 4/, C/sub 2/H/sub 6/, and C/sub 2/H/sub 2/ cracked from the original fuel of C/sub 3/H/sub 8/ observed. The soot burnout occurs mainly in the stoichiometric and fuel lean conditions near the flame front or in the downstream region. When the gas temperature is raised, both the soot formation and burnout rates increase. The final exhaustion of soot is determined by the combined effects of the formation and burnout, which are influenced by the temperature history through the flame.

Optical Measurements of Soot Particles in a Laminar Diffusion Flame

Abstract Abstract—Laser-light scattering and attenuation techniques are applied simultaneously in a complementary fashion to measure the properties of the soot particles in a laminar diffusion flame. The measurements of local soot particle size and number density in the laminar diffusion flame are made together with the measurements of soot mass concentration, gas species concentration and temperature in the same flame. The results are as follows. (I) The average diameters (D;v) of soot panicles in the flame lie between 50 and 120 nm. The largest particles probably are formed in the fuel-rich region just inside the position of the temperature peak. The number density of soot particles is in the range between 108 and 1010 particles/cm3 and the volume fraction occupied by the particles in the flame is estimated to be 10-7 to 3 X 10-6 cm 3/cm3 and is a maximum near the flame axis, The soot density is about 2 g/cm3cm. (2) Most likely soot is produced in the fuel-rich region just inside the flame front where u...

Simultaneous removal of NOX and fine diesel particulate matter (DPM) by electrostatic water spraying scrubber

In this study, experiments were performed with an electrostatic water spraying scrubber to evaluate its effectiveness for simultaneous removal of NOx and Diesel Particulate Matter (DPM) emissions in marine exhaust gas. The effects of several parameters, such corona power, gas flow rate and engine load, on the contaminant removals have been investigated intensively. The present study shows that for a given gas flow rate, the removal of DPM is enhanced with the increase of applied voltage. Total DPM removal efficiency was higher than 97% by electrostatic attraction, DPM with a range smaller than 1Όm is removed for higher efficiency. NO, NOx were removed with values higher than 20%, depending on Cl- concentration in the seawater and engine loads. As a result, the electrostatic water spraying scrubber would appear to be a promising alternative method for control of mass-based, as well as number-based DPM emissions.

Combustion Characteristics of Wood Powder and A-heavy Oil

The industrial carbon dioxide discharge is a serious problem of the global environment. The biomass is carbon neutral energy and can be used as an alternative fuel. The object of this paper is to cut down the fossil consumption in a small-scale oil-burning furnace by wood powder and A-heavy oil. The wood powder, which has a size of 150 pm and is made of thinned lumber, is blended into A-heavy oil flame. A wood powder nozzle is used to directly supply the wood powder to the flame in the same axial direction. The combustion characteristics are experimentally investigated. As the wood powder increases, the temperature and the calorific value in furnace is increased, CO concentration is decreased. The particulate matter produced by A-heavy oil is significantly decreased. It is found that the wood powder is available to energy saving and emission control.

Nitrous Oxide Emissions from Marine Diesel Engine Sources

The aim of this paper is to study the effect of ship operation on formation of N2O emissions and the influence of temperature changing in the exhaust pipe diesel engine. The data were taken from training ship Fukae Maru during the voyage project in September 2004 and the diesel engine experiment in the laboratory. Data from the Fukae Maru training ship were carried out at different operating conditions. Two sampling points, in the engine room and funnel were set up in the experiment. The N2O analyzer model 46C was used to measure exhaust emissions. A direct-injection diesel engine with naturally aspirated (model NF-19SK YANMAR) single cylinder was employed to test the emission and engine performance. The experiment data shows that in the 15 degree PPA, the nitrous oxide emissions higher than others condition.

Removal of Particulate Matter (PM) and NO x from marine exhaust gas by combining electrostatic water-spraying scrubber and emulsion oil

In this study, experiments were performed with combination using emulsion oil and an electrostatic water spraying scrubber to evaluate effectiveness for simultaneous removal of NOx and Particulate Matter (PM) emissions in marine exhaust gas. The effects of several parameters, such corona power, gas flow rate, on the contaminant removals have been investigated intensively. Total PM removal efficiency was higher than 99% by electrostatic water spraying scrubber and reduction in NO and NOx emission of up to 28-48% and 18-42%, respectively.

The effects of Electrostatic Precipitator in EGR system on the combustion and exhaust gas of marine diesel engines

Exhaust gas recirculation (EGR) is an effective way of reducing NOx, especially in the exhaust gas from automotive engines that has low particulate concentration, by suppressing the peak combustion temperature. Unlike automotive engines, exhaust gas from marine diesel engines that use low-grade fuel with high concentrations of sulphur and abrasive particles cannot be supplied to engine for EGR, unless the particulate is reduced. The author’s previous research indicates that an electrostatic precipitator (ESP) can successfully reduce marine diesel particulate matter. Hence, in this research, a combined EGR and ESP system capable of simultaneously reducing NOx and particulate matter (PM) was developed. The exhaust gas that was treated by ESP was supplied to the air intake manifold under various conditions, and the results show that a combined EGR/ESP system reduces NO and PM concentrations in exhaust gas. The combination system also improves the rate of heat release.

Characteristics of Combustion and Emission of Marine Four-stroke Medium-speed Diesel Engine with High Sulfur Containing Fuel

The amount of sulfur in fuel directly affects the emission of SOx from diesel engines. It also has an effect on the engine performance and emissions of PM, NOx and others. The object of this study is to investigate the influence of sulfur concentration in a medium-speed engine, which is being used as a main engine or dynamo engine in a lot of ships. The fuel used is of the high sulfur containing substance DBDS (Di-tert-butyl Di-sulfide) at various rates in the same “A” heavy oil. The following results were obtained. As the amount of sulfur concentration increases, the brake fuel consumption ratio increases, causing increase of SO2, decrease of NOx and no change of CO2, O2 and CO. ISF increases almost linearly, and though SOF shows a upward tendency at low load, it does not change at normal 75% load. Therefore PM which is the sum of ISF and SOF increases through 25 to 75% load.

Reduction System of Marine NOx and PM by Seawater Electrolysis Scrubber

Agreement of exhaust air pollution and substances from ships included in MARPOL Treaty (73/78) Annex VI of IMO Air Pollution Control, has been enforced since 19 May 2005. Ships by more than 130 kW class of diesel engine that sail within 200 nautical miles from the coast may cause the serious problems of pollution. It is necessary to develop a new control system for the pollutants emitted from the ships. In this study, a scrubber equipment was developed to reduce the pollutants of NOx and Particulate Matters (PM) in the exhaust tube. The equipment has three stage scrubbers that spray seawater, acid and alkaline water were generated by electrolysis of seawater. NO changes nitrocyl chloride (NOCl) with Cl2 in the acid water. This resulted 73% of reduction rate of NO. However, the reduction rate of NO and PM are 14.3% and 70% respectively at exhaust gas flow of 570 l/min.

Aging of Sheet Rubbers and Aluminum Alloy as Diesel Engine Parts after Exposure to Bio-diesel Fuel

Cross sections of silicon and nitrile sheet rubbers were increased to 1.06 and 1.32 times, respectively, by exposure to bio-diesel fuel (BDF) for 112 days. Tensile strength for nitrile sheet rubber was reduced by 41%, and that for silicon sheet rubber was reduced by 12%. These results indicate that aging of nitrile sheet rubber was more rapid than that of silicon sheet rubber in response to exposure to BDF, although the values for reduced tensile strength were around 7 MPa for both of them. No obvious aging on the surface of aluminum alloy was observed in the scanning electron micrographs.