Thermal Treatment

Abstract

The invention provides methods and apparatus for thermal treatment, e.g. for pyrolysis of lignin. The lignin is provided to a reaction chamber as a paste, which can reduce or avoid process difficulties encountered when heating lignin.

Description

BACKGROUND TO THE INVENTION[0001]1. Field of the Invention[0002]The present invention relates to thermal treatment, such as thermal treatment of lignin, and apparatus for thermal treatment e.g. of lignin. In particular, it relates to pyrolysis of lignin.[0003]2. Related Art[0004]Lignin is a component of cell walls of plants. It provides strengthening support to trees, and contributes to enabling plants to conduct water efficiently.[0005]Lignin is available as a by-product of industrial processes including pulping and paper making. In these processes, lignin may be removed from plant material such as wood, and so may be produced as a by-product.[0006]Processing of lignin is of particular interest because it can result in the production of useful and valuable products, such as phenolic compounds. Phenolic compounds include those having the moiety Ph-O—, wherein the phenyl group may be further substituted. Examples include phenol, catechol, guaiacol, syringol and vanillin. Other produc...

AI Technical Summary

Benefits of technology

The present invention provides a way to use lignin in a pyrolysis reactor by adding it as a paste to reduce its problems of low melting point and adhesiveness. Additionally, additives can be included to enhance the production of preferred products, such as phenolic products. These additives can be added when mixing the lignin with other components. This invention provides a more efficient and effective way to utilize lignin in a pyrolysis reactor for producing valuable products.

Problems solved by technology

In recent years, with an increasing production of cellulosic ethanol and the use of organosolv pulping processes, lignin processing has become more urgent and challenging.

However, pyrolysis of lignin (e.g. lignin derived from plant material such as wood) has not been straightforward.

As a result, it tends to melt before entering a pyrolysis reaction chamber, which is usually above about 500° C., leading to blocking of the feeding system.

In addition, lignin tends to cause char and other solids present in the reaction chamber to agglomerate.

This can lead to the formation of solid deposits, for example on the feeding system and reaction chamber walls.

This can block the reactor and stop it from functioning properly.

In the case of a fluidised bed pyrolysis reactor, pyrolysis of the melted lignin tends to produce a char agglomerate with the solid particles (e.g. sand) of the fluidised bed, which forms large pieces, leading to defluidization of the bed.

These problems have significantly limited the success of reported lignin pyrolysis.

The use of screw feeders was not successful due to the blockage at the end of the screw.

However, the maximum feeding was only 30-40 g because of the defluidization caused by char-sand agglomeration.

Probably, the screw feeder did not work well at high temperatures due to the effect of the cooling system reducing at these higher temperatures.

Images