The demand for petroleum has been rising rapidly due to increasing industrialization and modernization. This economic development has led to a huge demand for energy, most of which is derived from fossil fuel. However, the limited reserve of fossil fuel has led many researchers to look for alternative fuels which can be produced from renewable feedstock. Increasing fossil fuel prices have prompted the global oil industry to look at biodiesel, which is from renewable energy sources. Biodiesel is produced from animal fats and vegetable oils and has become more attractive because it is more environmentally friendly and is obtained from renewable sources. Glycerol is the main by-product of biodiesel production; about 10% of the weight of biodiesel is generated in glycerol. The large amount of glycerol generated may become an environmental problem, since it cannot be disposed of in the environment. In this paper, an attempt has been made to review the different approaches and techniques used to produce glycerol (hydrolysis, transesterification, refining crude glycerol). The world biodiesel/glycerol production and consumption market, the current world glycerin and glycerol prices as well as the news trends for the use of glycerol mainly in Brazil market are analyzed. The technological production and physicochemical properties of glycerol are described, as is the characterization of crude glycerol obtained from different seed oil feedstock. Finally, a simple way to use glycerol in large amounts is combustion, which is an advantageous method as it does not require any purification. However, the combustion process of crude glycerol is not easy and there are technological difficulties. The news and mainly research about the combustion of glycerol was also addressed in this review.

Glycerol: Production, consumption, prices, characterization and new trends in combustion

Soot processes in compression ignition engines

Power production from biomass derived pyrolysis liquids has been under development for the past few years. If technically successful, it would make decentralized bio-energy production possible. Several technologies and system components have been developed by academia, R&D organizations, and industrial companies in many countries. Much experience has been gained and many useful results published. The present work aims at reviewing the most significant experience in power generation from biomass liquids produced by fast pyrolysis processes. Power plant technologies addressed are diesel engines, gas turbines, and natural gas/steam power plants. Main results are reviewed and R&D needs identified for each technology. The analysis shows that even for the most promising solutions long-term demonstration has not yet been achieved. Pyrolysis liquid use in gas turbine plants and in co-firing mode in large power stations are technically most advanced. Recent work with diesel engines also appears quite promising.

http://www.combio-project.com/download/PDF/Power_generation_using_fast_pyrolysis_liquids_from_biomass.pdf

Power generation using fast pyrolysis liquids from biomass

Effects of soybean biodiesel on a DI diesel engine performance, emission and combustion characteristics

Performance and combustion characteristics of a di diesel engine fueled with waste palm oil and canola oil methyl esters

https://isiarticles.com/bundles/Article/pre/pdf/20428.pdf

Technologies for energetic exploitation of biodiesel chain derived glycerol: Oxy-fuels production by catalytic conversion

Running Light-Duty DI Diesel Engines with Wood Pyrolysis Oil

Some oxygenated hydrocarbons were tested as pure fuels in two different DI diesel engines, and their emission potential was compared to n-tetradecane combustion. Two colours pyrometry method was used to infer in-cylinder sooting tendency of tested fuels. Pure pyrolysis of the same fuels was also investigated in a conventional shock lube at high temperature (1700–2500 K) and pressure (9–13 bar), using light scattering/extinction methods. All oxygenated compounds tested in the engines exhibited a strong decrease of soot loading compared with tetradecane combustion. The long soot induction times, as measured in shock tube experiments, and the oxygen content of the fuel molecules seem to provide a plausible explanation of soot lacking in oxygenated fuels combustion. Emission measurements at the exhaust of a four cylinder engine fully confirm the trends obtained by two colours pyrometry and shock tube experiments. As a matter of fact, the oxygenated synthetic fuels strongly reduce both gaseous and total partic...

Experimental Characterization of Combustion Behaviour of New Diesel Fuels for Low Emission Engines

An extensive investigation has been carried out on the thermal behavior of biomass pyrolysis oil derived from different feedstocks (mixed hardwood, pine, and poplar). Experiments were performed on streams of monodispersed droplets (50–100 μm) and on large suspended droplets (300–600 μm). The small droplets were generated by a single-droplet generator and injected in a drop-tube furnace, the temperature of which ranged from 300 to 850°C. Light-scattering methods have been used to follow the process undergone by the pyrolysis oil droplets. The solid material, residual of the droplet heating and vaporization processes, has been examined by means of optical and scanning electron microscopy. Two different morphologies of residual particles have been observed at the exit of the furnace: (a) more compact, mechanically resistant spheres, with typical diameter of 10–40 μm, and (b) fragile, glasslike cenospheres with thin walls and menisci, with diameter of 100–200 μm. The large droplets were suspended at the exit of the furnace, using both a quartz fiber and an exposed junction thermocouple. The furnace temperature was varied between 400 and 1200°C. The phenomena, occurring during the vaporization and burning of each droplet, were followed by coupling the thermocouple measurement to high-speed visualization. The imaging was performed by means of fast digital video recording (50–250 frames/s) and high-speed cinematography (400–1000 frames/s). Temperature-time curves of the burning droplets show a stepped behavior, with two zones at constant temperature, at ∼100 and ∼450°C. The first step is due to the vaporization of water. The second plateau corresponds to the heating of heavy compounds due to selective vaporization and liquid-phase pyrolysis. Swelling, shrinking, and microexplosions with ejection of matter characterize this phase. The combustion of the droplets starts with an enveloping blue flame. The flame then develops a yellow tail of increasing size. After the flame extinction, the remaining char particle burns without residual.

Thermo-optical investigation of burning biomass pyrolysis oil droplets

A light-scattering anaysis based on Lorenz-Mie theory shows that the size and refractive index of transparent droplets can be determined by measuring the polarized components of the scattered light at two angles in the forward direction. The horizontally polarized cross section C(HH)(33°) depends exclusively on the droplet diameter, whereas the ratio C(HH)(33°)/C(HH)(60°) is a sensitive function of the refractive index and hence of the temperature. On this basis, a new optical system for measuring the temperature, size, and velocity of transparent droplets has been developed. This system can make possible the determination of droplet temperature within a few degrees centigrade. In addition, a critical review of the rainbow method to determine droplet temperature is also presented. These techniques have been applied to vaporizing tetradecane droplets (D(0) = 72 µm), which are heated up in a tube furnace with a temperature range of 20°-200 °C.

Maurizio Lazzaro

Papers

Technologies for energetic exploitation of biodiesel chain derived glycerol: Oxy-fuels production by catalytic conversion

Running Light-Duty DI Diesel Engines with Wood Pyrolysis Oil

Experimental Characterization of Combustion Behaviour of New Diesel Fuels for Low Emission Engines

Thermo-optical investigation of burning biomass pyrolysis oil droplets

Temperature and size of single transparent droplets by light scattering in the forward and rainbow regions