SOOT WATER CLEANING BY MEANS OF CONTINUOUS PRESSURE FILTRATION

摘要

In a pressure filtration system for cleaning residual quenching water of a gasifying device that gasifies carbon-containing fuels under elevated pressure, the soot water from the quencher is passed to a filter system (1), which has a number of pressure filter chambers operating alternately in filtering mode under gasifying pressure or in cleaning mode. The filtrate from the pressure filter chambers is passed to a quenching water reservoir, from which the quencher is fed with quenching water. This only entails small temperature and pressure losses with respect to the residual quenching water leaving, and only a small additional amount of energy has to be expended to overcome the remaining pressure difference to bring the filtrate that is to be returned back to the gasifying pressure. The invention, in which the residual quenching water is therefore cleaned substantially under gasifying pressure in a pressure filter, avoids flash evaporation of the residual quenching water into the vacuum area, with vapour cooling and a subsequent increase in pressure and reheating. In this way, the electrical energy requirement of the gasifying process itself can be reduced by orders of magnitude and the energy content and associated water content of the untreated gas can be set to the steam contents required for the CO shift reaction without additional amounts of heat being used up. This leads altogether to an improvement in the overall efficiency of IGCC and chemical synthesis processes. In an advantageous way, calcite precipitation is avoided in the soot water system, since no flash evaporation and preheating of the residual quenching water to be returned is required.