Pyrolysis oil
(Also called " bio-oil " or " Biocrudeoil " ) pyrolysis oil is a dark brown liquid which is obtained by pyrolysis of biomass at temperatures of about 500 ° C. Although vegetable origin, pyrolysis oil, in contrast to the substantially composed of vegetable oils, fatty acids from a wide variety of chemical compounds. In addition to its use as biofuel, heating component or energy-rich intermediate pyrolysis oil can be used as source of raw materials for chemical applications.
- 5.1 Energy Use
- 5.2 Chemical Processing
Process
Pyrolysis of biomass is split into solid, liquid and gaseous components. As solid components as wood or charcoal are obtained when non-condensable components ( pyrolysis ) fall of hydrogen, carbon monoxide and dioxide, and methane. The liquid phase is condensed at room temperature and ambient pressure. The calorific value of 15-30 MJ / kg, which is about half as high as that of natural gas or heating oil. The use of wood as Pyrolyserohstoff the yield of pyrolysis oil is approximately 65 to 75 %.
Composition
Pyrolysis oil is composed of a plurality of components, such as oxo - carboxylic acids, phenols, aldehydes and ketones, such as alcohols, furans, aldehydes, phenols, organic acids and oligomeric carbohydrate and lignin. It can be proven that some monomer present as well as polymeric lignin several hundred compounds. Up to 38 % of pyrolysis oil consists of water, on the one hand, on the other hand consists of the water content of the biomass from the eden result in breaking the chemical bonds of water of reaction.
Typical Properties
Pyrolysis is an acidic liquid with dark red to dark brown in color. Unlike mineral oil, it is not miscible with hydrocarbons, in ethanol, it is unlimited, limited miscible with water. Depending on the water content and content of volatile constituents vary the viscosity. The calorific value of pyrolysis oil is about 42% of its oil.
The pour point is between -12 ° C and -33 ° C, the cloud point at about -21 ° C. The flash point is between 40 and 100 ° C. In the diesel engine, it is not self-igniting; the cetane number is only about 10 pyrolysis oil is shelf stable for long periods. By polymerization and the viscosity reaches a maximum after about 12 months. The oil is oxidized in air, and degassed with time. The smell of pyrolysis oil is slightly pungent and reminiscent of smokehouses.
Typical properties of pyrolysis oil shown in the following table:
Preparation
Before using pyrolysis oil needs to be fully processed according to use more or less. For use in engines, for example, require engine manufacturers to comply with limit values for particulate levels and size composition and for the viscosity. For preparation are physical and chemical methods.
Physical treatment
Contamination by solid particles are already removed with multi cyclones or hot gas filters in the stream of the hot pyrolysis gas before it condenses into pyrolysis oil. It is also a cold filtration of the oil. Low viscosity, the oil by adding water or low-order alcohols.
Chemical treatment
By hydrogenation (saturation of reactive double bonds with hydrogen), the ( storage) stability of pyrolysis oil can be increased. A higher proportion of hydrogen is also achieved through the process of cleavage by hydrogenation ( hydrocracking and hydro - deoxygenation ). This also reduces the oxygen content in the pyrolysis. The high oxygen content of the starting material, however, due to a high consumption of hydrogen and therefore makes the process very expensive. Catalysts such as zeolites or other inorganic materials can be removed from the oil by converting oxygen into carbon dioxide, this results in free and condensed aromatics.
Applications
There are various ways of further processing of the pyrolysis oil. In addition to the energetic use as fuel or heating component use as a source of raw materials for chemical applications is possible. The use of pyrolysis oil is largely still in development.
Energetic use
By hydrogenation pyrolysis oil can be converted into fuels. In boilers they can be burned in principle similar to heavy fuel oil. Stationary diesel engines need to be warmed up before use of pyrolysis oil with conventional fuel, negatively include the lack of lubricating properties. Several properties of the pyrolysis oils as a high ignition temperature, viscosity, acidity and thermal lability and increased combustion emissions for NOx and CO more difficult to use.
As transportable intermediate product in the production of BtL fuel from biomass pyrolysis oil plays an important role in the concept of a two-stage production Synthetic biofuels. For biomass to be processed from the close vicinity to pastes or slurries from pyrolysis and coke in decentralized Schnellpyrolyseanlagen, which are then transported to a central facility for the production of biofuels. A pilot Schnellpyrolyseanlage under such an approach runs the Forschungszentrum Karlsruhe since 2007
The use of pyrolysis oil in thermal power stations is examined in the context of industrial and political projects funded.
Chemical Processing
The chemical processing is so far little explored. The only commercial application on a larger scale is currently use as a smoke flavoring ( liquid smoke ) subject to review by the European Commission. Other options include the isolation of Lävoglucosan ( the monomeric units of cellulose) for the control of certain chemical reactions, as well as the use as surfactants, polymers and biodegradable resins. Also, the isolation of phenolic resins for adhesives is possible. Unchanged pyrolysis oil is used as a partial substitute of phenol and formaldehyde in particle board in question, as well as a reactant in the production of nitrogen fertilizers with retarded nutrient release.
Swell
Martin cold Schmitt, Hans Hartmann and Hermann Hofbauer (eds. ), 2009: Energy from biomass. Fundamentals, techniques and procedures. Springer Verlag, 2nd edition, pp. 685-690, ISBN 978-3-540-85094-6