Igniting an underground coal seam in an underground coal gasification process, ucg

Abstract

An ignition apparatus (150) configured to ignite an underground coal seam (151). The ignition apparatus (150) comprising an ignition system, a positioning system, a sensor (170) and a controller (165). The ignition system comprises ignition means and an ignition tool (155) for igniting the underground coal seam (151) from within the well channel (154) or well liner encasing the well channel (154). The positioning system comprises coiled tubing (156) connected to the ignition tool (155) and extendible through a well head (153) within the well channel (154) to position the ignition tool (155) at a desired location within the well channel (154). The positioning system further comprises a spool (157) for transporting and dispensing the coiled tubing (156).

Description

FIELD OF THE INVENTION[0001]This invention relates to a method and apparatus for igniting an underground coal seam, for in-situ conversion of coal to product gas.BACKGROUND OF THE INVENTION[0002]Underground coal gasification (UCG) is a process by which product gas is produced from a coal seam by heating the coal in situ in the presence of an oxidant. The product gas is typically referred to as synthesis gas or syngas and can be used as a feedstock for electricity or chemical production, for example.[0003]Conversion of coal into product gas takes place in a well which typically includes a well channel of sorts extending through the coal seam. Such a channel can be formed by one or more bore holes drilled into the coal seam that are in fluid communication with one another. The channel is also in fluid communication with an injection well, a production well as well as perhaps one or more ignition or service wells that extend from ground level to the well channel. Typically, oxidant is ...

AI Technical Summary

Benefits of technology

The technical effect of this patent is to provide a safe and cost-effective method for igniting or re-igniting coal from an underground coal seam, or to provide a useful or commercial choice for the public.

Problems solved by technology

One of the major challenges for UCG is to ignite the coal underground, particularly in a safe and cost effective manner.

One problem associated with UCG is that a combustion front produced at a combustion zone does not always progress along a coal seam as proposed in theory, and practically a coal seam may need to be reignited at different sites along the coal seam so as to maximise the production and life of the coal gasifier.

One of the problems associated with UCG when employing a well channel that extends substantially horizontally through the coal seam is that more than one vertically extending ignition well (bore hole) may be required in order to ignite / re-ignite the coal seam / gasifier at multiple locations, as installing ignition wells is an expensive and time consuming process.

In addition, the use of TEB or silane can be dangerous for handlers due to the highly volatile nature of the material when exposed to air and any mistake in handling such materials can expose them to air and initiate fire or explosion events.

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