So you're not using an external source (primary energy) to drive the gasification process? Its just combusting the coal and capturing the products of that? If so, could one retrofit existing coal burners and use them to produce these products? Or is a slower process?
Other than the energy in the coal itself, no. Oh, the plant has to have electricity and live steam, but this can be powered by energy-converions/recovery steps in the process itself.
"Its just combusting the coal and capturing the products of that?
In the final analysis, yes. The process does require pretty tight control of the reaction conditions to work correctly.
"If so, could one retrofit existing coal burners and use them to produce these products? Or is a slower process?"
No--it takes a plant specifically designed for gasification to carry out the process effectively (i.e. with high conversion efficiency)--however the processes are NOT slow in and of themselves---they just have to be "tightly tuned" to work properly