TABLE OF CONTENTS In the practical realization of gasification processes a broad range of reactor types has been and continues to be used. For most purposes, these reactor types can be grouped into one of three categories: moving-bed gasifiers, fluid-bed gasifiers, and entrained-flow gasifiers. The gasifiers in each of these three categories share certain characteristics that differentiate them from gasifiers in other categories. Some of these characteristics are summarized in Table 5.1.
| Category | Moving-bed | Fluid-bed | Entrained-flow | ||
|---|---|---|---|---|---|
| Ash conditions | Dry bottom | Slagging | Dry ash | Agglomerating | Slagging |
| Typical processes | Lurgi | BGL | Winkler, HTW, KBR, CFB, HRL | KRW, U-Gas | KT, Shell, GEE, E-Gas, Siemens, MHI, PWR |
| Feed characteristics | |||||
| Size | 6 50 mm | 6 50 mm | 6 10 mm | 6 10 mm | 100 m |
| Acceptability of fines | Limited | Injection through tuy res | Good | Better | Unlimited |
| Acceptability of caking coal | Yes (with stirrer) | Yes (with stirrer) | Possibly | Yes | Yes |
| Preferred coal rank | Any | High | Low | Any | Any |
| Operating characteristics | |||||
| Outlet gas temperature | Low (425 650 C) | Low (425 650 C) | Moderate (900 1050 C) | Moderate (900 1050 C) | High (1250 1600 C) |
| Oxidant demand | Low | Low | Moderate | Moderate | High |
| Steam demand | High | Low | Moderate | Moderate | Low |
| Other characteristics | Hydrocarbons in gas | Hydrocarbons in gas | Lower carbon conversion | Lower carbon conversion | Pure gas, high carbon conversion |
| Source: Adapted from Simbeck et al., 1993. |
Moving-bed gasifiers (sometimes called fixed-bed gasifiers) are characterized by a bed in which the coal moves slowly downward under gravity as it is gasified by a blast that...
