Extractive gas-phase sampling of the reaction zone of a pressurized entrained-flow coal gasifier

Abstract

A novel extractive gas-phase sampling system was developed for use in a pressurized entrained-flow coal gasifier. The system comprised three parts: a water-cooled probe through which the sampled gases travel, a pneumatic cylinder that directs the radial sampling location, and the control system. The system was designed for safe sampling of the harsh environment in gasifiers and can help understand spatial distribution of concentrations in such a system. To confirm operation of the sampling system, gas-phase samples were extracted from the reaction zone of a 1ton/day pilot entrained-flow coal gasifier operating at a pressure of 11bar and at temperatures ranging from 1370 to 1540°C. Concentrations of carbon monoxide and hydrogen decreased with increasing temperature while carbon dioxide increased with temperature, a result of the higher oxygen/fuel ratio needed to achieve the higher temperature. Synthesis gas (syngas) heating values decreased correspondingly with increasing temperature and the heating value of the syngas exiting the gasifier was higher than for syngas extracted from the reaction zone. Under conditions tested, no statistically significant variation in gas composition with radial position was observed.