Autori: Valentin A. SOLOIU, Yoshinobu YOSHIHARA, Kazuie NISHIWAKI, Masakatsu HIRAOKA, Kazuki HAYASHI and Kazutaka SHINCHI

Editorial: Japanese Society of Marine Engineers, Proceedings of the 7th International Symposium on Marine Engineering, Tokyo, October 24th to 28th, 2005, p.8, 2005.

Rezumat:

With the continuous rising of oil prices and the limited petroleum resources, a higher importance is given to bio-fuels that are a renewable source of energy and do not contribute to the overall increase of the green house effect.
Internationally, extensive research was performed over the years to establish the Coal-oil mixtures (COM) and Coal-water mixtures (CWM).
On the other hand, bio-fuels obtained from biomass have a high potential for CO2 protection because the wood is a renewal source of energy and does not contribute like coal, to the overall green house effect.
In Japan, the timber industry is very large and producing around 9,000,000 tons of waste per year, namely of wood chips.
In Rits University, Eco-Technology Research Center, a comprehensive research took place for efficient energy recovery from this abundant biomass resource. Producing fuels of this sort has high commercial importance for large power generation plants consuming massive quantities of heavy fuel oil. The authors developed the prototype of the industrial production of Bio-COM fuels and applied them for combustion in a diesel engine instead of heavy fuel oils. An effective emulsification process with highly surface-active substances and dispersing devices, provided the possibility to produce stable and highly dispersed Bio-COM fuels not segregating out in layers for a longer time in the presence of surfactants.
The employment of Bio-COM fuel is intended to save fossil fuels and would reduce green house emissions into the atmosphere during combustion.
The studies on the new Bio-COM fuel showed that the maximum temperature to which the charcoal is obtained strongly affect its composition content and therefore the combustion process. The size distribution of the charcoal particle was measured by a laser diffraction particle sizer and microscope investigation. The study revealed that through a three steps grinding process, charcoal particles, between 1-50 micrometers, with an average of 10 micrometers could be produced. The charcoal was emulsified with HFO-A by an original process proposed by the authors. The kinematic viscosity of the Bio-COM fuels was measured and the results confirmed the possibility of injection. The TGA and DTA were conducted to investigate the distillation and the combustion properties. They revealed the two-stage combustion process of the Bio-COM fuel.
The results of the laser investigation of droplets in sprays from the emulsified fuel show that in spite a relatively higher viscosity, the fuel, a non-Newtonian fluid, is able to atomize to 35-40 m SMD. This shows the possibility to be used with the present design injection systems and an alternative of the heavy fuel oil. The engine investigation proved that Bio-COM fuels can be successful burned in a diesel engine, the engine’s nominal power could be reached, and the efficiency maintained.
Initially, the emissions of NO were higher for Bio-COM but they could be improved by reducing the injection timing. The smoke emissions were better at any load for Bio-COM fuel compared with HFO-A. Finally, the emissions of Bio-COM were better at 13 deg. BTDC than those of HFO-A with the original engine settings.
To summarize, the new fuel offers good prospects for combustion but problems with the stability of the fuel and the injection process have to be solved.
The study showed that the new emulsification process proposed by the authors is able to produce a new class of fuels from biomass charcoal, practical for diesel generation plants, saving heavy fuel oil and improving the environment. The research is ongoing to clarify all the aspects of the industrial application including boiler combustion.

Cuvinte cheie: Bio-COM fuel, diesel generation systems, combustion, emissions, biomass, wood, charcoal, recycling