Fast pyrolysis utilizes biomass to produce a product that is used both as an energy source and a feedstock for chemical production. Considerable efforts have been made to convert wood biomass to liquid fuels and chemicals since the oil crisis in mid-1970s. This review focuses on the recent developments in the wood pyrolysis and reports the characteristics of the resulting bio-oils, which are the main products of fast wood pyrolysis. Virtually any form of biomass can be considered for fast pyrolysis. Most work has been performed on wood, because of its consistency and comparability between tests. However, nearly 100 types of biomass have been tested, ranging from agricultural wastes such as straw, olive pits, and nut shells to energy crops such as miscanthus and sorghum. Forestry wastes such as bark and thinnings and other solid wastes, including sewage sludge and leather wastes, have also been studied. In this review, the main (although not exclusive) emphasis has been given to wood. The literature on woo...

Pyrolysis of Wood/Biomass for Bio-oil: A Critical Review

This paper provides an updated review on fast pyrolysis of biomass for production of a liquid usually referred to as bio-oil. The technology of fast pyrolysis is described including the major reaction systems. The primary liquid product is characterised by reference to the many properties that impact on its use. These properties have caused increasingly extensive research to be undertaken to address properties that need modification and this area is reviewed in terms of physical, catalytic and chemical upgrading. Of particular note is the increasing diversity of methods and catalysts and particularly the complexity and sophistication of multi-functional catalyst systems. It is also important to see more companies involved in this technology area and increased take-up of evolving upgrading processes. © 2011 Elsevier Ltd.

Review of fast pyrolysis of biomass and product upgrading

Fast pyrolysis of biomass is one of the most recent renewable energy processes to have been introduced. It offers the advantages of a liquid product, bio-oil that can be readily stored and transported. Bio-oil is a renewable liquid fuel and can also be used for production of chemicals. Fast pyrolysis has now achieved a commercial success for production of chemicals and is being actively developed for producing liquid fuels. Bio-oils have been successfully tested in engines, turbines, and boilers, and have been upgraded to high-quality hydrocarbon fuels, although at a presently unacceptable energetic and financial cost. The paper critically reviews scientific and technical developments in applications of bio-oil to date and concludes with some suggestions for research and strategic developments.

Overview of Applications of Biomass Fast Pyrolysis Oil

Renewable fuels and chemicals by thermal processing of biomass

Fast pyrolysis for production of liquids has developed considerably since the first experiments in the late 1970s. Many reactors and processes have been investigated and developed to the point where fast pyrolysis is now an accepted feasible and viable route to renewable liquid fuels, chemicals and derived products. It is also now clear that liquid products offer significant advantages in storage and transport over gas and heat. These advantages have caused greater attention to be paid to fast pyrolysis, leading to significant advances in process development. The technology of fast pyrolysis for liquids is noteworthy for the wide range of reactor configurations that have been developed to meet the stringent requirements for high yields of useful liquids, for use as a fuel in boilers, engines and turbines and as a source of chemical commodities. This review summarizes the key features of fast pyrolysis and the resultant liquid product and describes the major reaction systems and processes that have been developed over the last 20 years.

http://ehsan13967.persiangig.com/document/pyrolysis5.pdf

Fast pyrolysis processes for biomass

Addition of alcohols was found to improve the homogeneity, decrease the viscosity and density, lower the flash point, and increase the heating value of pyrolysis liquids. Alcohol addition also lowered the viscosity and molecular mass increase during the aging of pyrolysis liquids. The reduction in the viscosity change was primarily due to a stabilizing effect of alcohols on the water-insoluble high molecular mass lignin-derived fraction. Other effects include the formation of acetals in reactions of alcohols with aldehydes, ketones, and anhydrosugars. Low (≤5 wt %) alcohol additions prevented aging reactions by a few months, while the higher (≥10 wt %) ones retarded them by almost a year. Methanol was the most effective alcohol of those tested (methanol, ethanol, isopropanol). By improving solubility, the alcohols also enhanced the separation of the extractive-rich top layer in the pyrolysis of forestry residue by decreasing its volume and increasing the concentration of extractives and solids in the top ...

Fast Pyrolysis of Forestry Residue and Pine. 4. Improvement of the Product Quality by Solvent Addition

The commercialization of biomass-derived pyrolysis liquids for use in heat and power applications is dependent on the ability to successfully provide a fuel of acceptable quality to an end user at a competitive price. One of the intentions of the European Union (EU) Altener 4.1030/C/00-015/2000 project was to derive standards for biomass-derived pyrolysis liquids, based on a consensus between providers of the equipment (boilers, engines, and turbines) and the producers of the liquids. Five basic properties (homogeneity, water content, solids content, stability, flash point) for the liquids are used as the primary criteria for pyrolysis liquid evaluation. Specific values are proposed to ensure that pyrolysis liquids meet a minimum grade that is acceptable for use as a fuel oil in boilers and engines. Data on emissions from boilers, engines and turbines are presented. Preliminary long-duration test data from boiler use are available to allow more-detailed specifications on secondary properties to be made. T...

Norms and Standards for Pyrolysis Liquids. End-User Requirements and Specifications

A handicap facing both the producer and the user of fast-pyrolysis oils is the lack of a description of these oils that is adequate for commercial applications. These oils are highly oxygenated and are relatively immiscible with petroleum oils. Under the current IEA Biomass Energy Agreement, the new Pyrolysis Activity (PYRA) has taken on the task of establishing a useful description of a series of pyrolysis oils. This series roughly parallels that of petroleum fuel oils already described, so that with as few changes as possible to the users’ equipment, a bio-oil could be used in place of the equivalent petroleum-derived oil. The specifications for biomass pyrolysis oils differ in the density, heating value, water content, and corrosiveness. These proposed specifications are presented for discussion by the biomass conversion community and feedback to the Pyrolysis Activity.

Proposed Specifications for Various Grades of Pyrolysis Oils

The economic viability of power production in a diesel power plant utilizing flash pyrolysis oil produced from sawmill wastes in Finland has been investigated. A combination of biomass feedstock costs, pyrolysis oil fuel properties (ignition quality, lubricating properties, combustion speed and duration, emissions, etc.) and their effect on power plant investments and maintenance will ultimately determine electricity busbar costs and the economic competitiveness of the concept. Pyrolysis oil is not a suitable fuel for a conventional diesel engine as such. The preliminary tests with additive treated pyrolysis oil demonstrated, however, that once ignition has taken place, pyrolysis oil burns rapidly. Pyrolysis oil may be a suitable primary fuel for a diesel engine with a pilot injection system, which secures the ignition of the main fuel.

Use of pyrolysis oil in a test diesel engine to study the feasibility of a diesel power plant concept

Flash pyrolysis liquid was combusted with simple pressure atomisation equipment commonly used with light fuel oils in intermediate size boilers. With a number of modifications to the combustion system, carbon monoxide (CO) and nitrous oxide (NOx) could be reduced to acceptable levels: CO 2 times higher than from light fuel oil. Contributions to high particulate emissions were from high solids content (0.5–0.7 wt%) and poor atomisation caused by high viscosity of the samples (> 20 cSt at 80 °C).

Steven Gust

Papers

Fast Pyrolysis of Forestry Residue and Pine. 4. Improvement of the Product Quality by Solvent Addition

Norms and Standards for Pyrolysis Liquids. End-User Requirements and Specifications

Proposed Specifications for Various Grades of Pyrolysis Oils

Use of pyrolysis oil in a test diesel engine to study the feasibility of a diesel power plant concept

Combustion Experiences of Flash Pyrolysis Fuel in Intermediate Size Boilers