Autothermal process type, gasification

The different gasification processes can be characterized 1) by the type of coal used and 2) by the coal s physical and chemical properties. On the other hand, the processes differ in the technology involved. For example the heat supply can be allothermal (i.e., external heating) or autothermal (i.e selfheating) and the reactor can be fixed-bed, fluidized-bed or entrained-bed. Furthermore, the actual gasification reaction and the gas composition are determined by46 ... 

The important factors in coal conversion are the physical and chemical properties of the coal, heat supply (autothermal or allothermal), reactor type (fixed bed, moving bed, fluidized bed, or entrained bed), gasification agent (air, oxygen, steam, or a combination thereof), and process conditions. Typically, coal conversion is carried out at high temperatures (900—1000 C) be-... 

Different types of autothermal coal gasification processes used on a large scale are existent as shown in Fig. 5-7. Lurgi, Winkler, Koppers-Totzek, and their modifications, respectively. Their charactenstic features are summanzed in Table 5-1. 

To achieve temperatures in a reactor above 700 °C to maintain the reaction of gasification agent and feedstock, heat can be either added externally or generated internally. Based on heat supply to the process, allothermal, autothermal, and hydrogenating processes are distinguished. The main characteristics of the different types of heat supply are shown in Table 4.1. 

---