Gasifier moving bed

Characteristics of moving-bed gasifiers are low gasification temperatures, relatively low oxygen requirements, relatively high methane content in... 

The importance of these concepts can be illustrated by the extent to which the pyrolysis reactions contribute to gas produdion. In a moving-bed gasifier (e.g., producer-gas gasifier), the particle is heated through several distinct thermal zones. At the initial heat-up zone, coal carbonization or devolatilization dominates. In the successively hotter zones, char devolatihzation, char gasification, and fixed carbon... 

There are only three types of processes using moving-bed gasifiers (BGL, BHEL, Lurgi) developed at industrial scale. They are the most mature technologies of the three types of... 

The numerous coal gasification systems available today can be reasonably classified as one of three basic types a) moving-bed, b) fluidized-bed, and c) entrained-bed. All three of these types utilize steam, and either air or oxygen to partially oxidize coal into a gas product. The moving-bed gasifiers produce a low temperature (425 to 650°C 800 to 1,200°F) gas containing... 

FIGURE 3 Schematic of a moving bed gasifier. [Reprinted with permission from Probstein, R. F., and Hicks, R. E. (1990). Synthetic Fuels, pH Press, Cambridge, MA.]... 

A model for transient simulation of radial and axial composition and temperature profiles In pressurized dry ash and slagging moving bed gasifiers Is described. The model Is based on mass and energy balances, thermodynamics, and kinetic and transport rate processes. Particle and gas temperatures are taken to be equal. Computation Is done using orthogonal collocation In the radial variable and exponential collocation In time, with numerical Integration In the axial direction. 

The exit gas temperature for a fluidized-bed gasifier is higher than that for a moving-bed gasifier. The higher temperature results in further reaction of the pyrolysis products, and, therefore, the product gas contains a much lower concentration of tar/oil. However, particle attrition generally leads to higher levels of... 

A moving bed gasifier is a vertical reactor with countercurrent flowing gas and solids streams. Coal enters the top of the reactor and ash (and/or clinker or molten slag) is removed from the bottom. A mixture of steam and oxygen (or air) enters the bottom of the reactor and the raw product gas exits from the top. 

Examination of state-of-the-art thermal biomass gasification technology shows that moving-bed gasifiers have been studied and extensively tested... 

Groeneveld, M.J. (1980). The co-current moving bed gasifier, Ph.D.thesis, Twente University of Technology, Enschede, Netherlands. 

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