Method of gasifying carbonaceous material and a gasification system

Abstract

A method of gasifying carbonaceous material is described. The method comprises a first step of pyrolysing and partially gasifying the carbonaceous material to produce volatiles and char. The volatiles and the char are then separated and, subsequently, the char is gasified and the volatiles are reformed. The raw product gas is then finally cleaned with char or char-supported catalysts or other catalysts.

Description

FIELD OF THE INVENTION[0001]The present invention relates to a method of gasifying carbonaceous material and a gasification system.BACKGROUND OF THE INVENTION[0002]Gasification refers to the conversion of a solid or liquid material, such as a carbonaceous material, into a gaseous fuel. Gasification is of interest for many low-emission technologies in chemical and energy industries.[0003]Gasification of a carbonaceous material can be conceptually divided into two steps although a clear distinction between the two steps is not possible. As the (solid) carbonaceous material is heated up, a mixture of gas and vapour (“volatiles”), including moisture of the carbonaceous material, is released from the carbonaceous material, leaving a solid residue (“char”). Both the volatiles and the char then react with gasifying agents such as H2O and O2 to form a product gas.[0004]Low-rank carbonaceous fuels such as brown coal (lignite), peat, biomass and solid wastes are particularly suitable for gasi...

AI Technical Summary

Benefits of technology

The patent involves a method for treating raw product gas by passing it through a catalyst bed. This results in several effects including the removal of impurities and the increase of hydrogen content in the product gas. This method helps to produce a cleaner, more valuable gas for further use in various applications. The gasification system also reduces interactions between volatile-char components, minimizing the formation of harmful byproducts.

Problems solved by technology

Gasification of a carbonaceous material can be conceptually divided into two steps although a clear distinction between the two steps is not possible.

The complete reforming of the tarry components of the volatiles is one of the most important considerations in the design of a gasifier because the removal of tar is cumbersome and costly.

Secondly, low rank fuels often contain well-dispersed alkali and alkaline earth metallic (AAEM) species that can volatilise easily during pyrolysis and gasification.

The volatilised AAEM species in the gasification product gas can cause corrosion / erosion of turbine / engine components.

Thirdly, char and volatiles from low-rank fuels are very reactive.

In the presence of volatile-char interactions, increasing the gasification temperature does not always lead to significant improvement in the gasification rates.

The removal of various undesirable components such as tarry materials, AAEM vapour, particulates and H2S / NH3 / HCl from the gasification product gas normally adds to the overall gasification process complexity and forms an important portion of the overall gasification capital and operating costs.

When these undesirable species are removed through liquid (e.g. water) scrubbing, a liquid waste stream is generated that must be further treated at great expense.

However, these catalysts often deactivate easily.

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