Pyrolysis is the decomposition of a chemical compound by the application of heat.
Gasification is the act or process of transforming a substance into gas
Pyrolytic decomposition of organic compounds into gaseous, liquid and solid fractions can be considered a subset of gasification. Pyrolysis gas contains hydrocarbon gas, carbon monoxide, hydrogen and some CO2 and is of higher calorific value than the gas produced by partial oxidation of carbon.
Carbon rich material e.g. coke or charcoal may be gasified by partial oxidation to yield a lean gas comprising nitrogen, carbon monoxide and carbon dioxide. Steam may be added and the air replaced partially or fully by oxygen in order to make a better quality gas comprising carbon monoxide, carbon dioxide and hydrogen.
There are many processes combining these steps to produce usable fuel gases of greater or lesser usefulness and quality. In some cases the gas is cooled and cleaned for remote use, and in others the hot dirty gas is immediately combusted to produce heat in a boiler.
Pyrolysis and gasification have become popular concepts for developers of small scale waste to energy plants, and a plethora of systems are in various stages of development.
We have worked on many of these systems, and indeed continue to do so; but find the same basic questions come up time after time: