Gasifier configurations

The processes that have been developed for the production of synthetic natural gas are often configured to produce as much methane in the gasification step as possible thereby minimizing the need for a methanation step. In addition, methane formation is highly exothermic which contributes to process efficiency by the production of heat in the gasifier, where the heat can be used for the endothermic steam—carbon reaction to produce carbon monoxide and hydrogen. 

Figure 6.5 shows the process configuration of different FB gasification concepts, from single-reactor concepts to twin fluid-bed systems. The FB gasifiers are operated in a typical temperature window of 800-950°C. Producers of such FB gasifiers (also including air... 

Depending on the gasifier system configuration, operating conditions, and gasification agent, four types of synthetic gas can be produced ... 

Coal gasification technologies can be classified according to the flow configuration of the gasifier unit. The primary configurations are ... 

Low- and medium-energy gasifiers have been built and operated using a variety of configurations. Some of the more common... 

A potential source of particulates is char formed when the biomass feedstock is incompletely gasified. These particles undergo devolatilization and subsequent reactions at gasification temperatures that leave them less reactive than fresh biomass feedstock. They can pass through the gasifier before they are completely gasified, particularly in those configurations with turbulent beds. Char entrained in the product gas also represents unconverted biomass that contributes to lower conversion efficiencies. 

Gasifiers have been designed in various configurations [4, 5, 24], each having its own advantages and disadvantages, in terms of product gas composition and operating parameters. 

Currently there is great interest in alternate fuels manufacture, and plant configuration studies are published by the dozen. Such configurations usually include a "Claus process" box all too often the material fed into the box could not be handled by any known Claus-type process. This paper is meant to point out some of the problems needing recognition, and some of the solutions. One solution is a new process suited to some coal gasifiers. 

Coal gasifier designs are almost as numerous as the many different types and ranks of coal. The basic configurations, hardware, and operations that have been considered are described here because several of them are applicable to biomass gasification (c/. National Academy of Engineering, 1973, and accompanying references). 

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