Entrained flow gasifiers consist of a co-current plug flow reactor and have been extensively studied and used for coal gasification. The gas and particle residence times in the reactor are very short (a few seconds), which requires very small size feedstock (100 ц-m) and very high temperature (>1,000 °C) to maximize conversion. There are two types of entrained flow gasifiers: slagging and non-slagging. In the slagging gasifier, the ash melts in the gasifier, flows down the walls of the reactor and finally leaves the reactor as a liquid slag. This type of entrained flow gasifier is preferred for biomass. In a non-slagging gasifier, the walls are free of slag, which is suitable for feedstock with low ash content [71]. Some of the advantages of entrained flow gasifiers are low tar and methane content, high carbon conversion, and ash existing as slag. Furthermore, the reactor can be operated, with a wide variety of feedstock at high pressure and temperature. Due to some problems associated with biomass molten ash and the use of very fine biomass particles, however, the use of an entrained flow biomass gasifier has been rather limited. One example of an entrained flow gasifier application for biomass is the Choren process with a maximum capacity of 45 MW h and using wood as feedstock [72].