Production of a nitrogen-lean gas and gasification plant

摘要

In a process for producing nitrogen-lean or virtually nitrogen-free gas through gasification of heterogeneous, biogenic fuels and plastic materials, the first step is for the fuel which is to be gasified to be contacted in the absence of air with the hot bed material of a fluidized bed combustion system and for it to be thereby at least partially degassed in the presence of water vapour and/or CO2. The resulting residual fuel is fed into a fluidized bed 2 comprising a circulating bed material and combusted therein, whereby the bed material is heated and, after its separation from the off-gas, is recycled back into the antechamber 1. The gasification plant for carrying out the process is formed in a housing of an internally circulating fluidized bed, wherein the antechamber 1 is used for recycling the hot bed material and is constructed as a gasification space, whereas the actual fluidized bed 2 is constructed as a combustion zone. For binding the bed material into the fluidized bed 2 and also for recycling the hot bed material into the antechamber 1, there are provided sluicelike devices. More particularly, the bed material is sand mixed with catalytically active nickel and/or niobium compounds. This lowers the gasification temperature and regulates the gas composition especially in the direction of a reduced CH4 content.