A key issue in oxy-gasification and oxy-co-gasification is the operation of an oxygen-blown gasifier.
Proper gasifier operation is more critical than boiler operation, because it does not consist in just maximising efficiency but other issues, that in turn requires keeping several output variables (gas composition and gasification temperature) in correct ranges and maximising fuel/gas conversion by adjusting two input variables (oxygen and steam that are introduced in the gasifier). Gasification temperature is a variable that cannot be measured but has to be kept in a right range because it determines not only efficiency but also safe operation. An error in oxygen measurement could cause either very high temperatures that can damage the equipment or (in slagging gasifiers) low temperatures that can stop slag flow and blocking. Besides, although output variables could be considered separately, a modification in an input variable implies changes in all output variables, so that all dependencies should be understood and integrated.
In oxy-co-gasification, fuel modification is an additional difficulty. In this work, the problem of gasifier operation in oxy-gasification and oxy-co-gasification is tackled. First, a validated model of the gasifier of an IGCC power plant is applied to simulate the oxy-co-gasification of coal, coke and up to 10% of several types of biomass, in order to obtain the operation strategies depending on the fuel mixture. Second, the operation maps are applied as a tool for improving gasifier operation. These maps constitute a graphic tool that helps to operate the gasifier in a safe and efficient way. They can be built by using a model or directly from plant data.
The case of study is Elcogas IGCC Power Plant in Puertollano (Spain). This is a demonstration project where several European companies have worked together (it was selected as a target project of the THERMIE program of the European Union).