OIL GASIFICATION AND PARTIAL OXIDATION OF NATURAL GAS
Technologies for the gasification of liquid and gaseous feeds were developed at the end of the 1940s by Texaco and in the early 1950s by Shell. These two technologies have dominated this segment of the market since that time. In recent years Lurgi has begun marketing a third technology, known as multipurpose gasification (MPG), which was originally developed out of its coal gasification process specifically to handle the tars produced there. Montecatini and GIAP also developed technologies, but neither achieved commercial success.
Certain key features of all three processes are similar. All use entrained-flow reactors. The burners are top-mounted in the downflow, refractory-lined reactor vessels. Operation temperatures are similar (in the range 1250-1450°C). When operating on liquid feed, all three processes produce a small amount of residual carbon, which is necessary to sequester the ash from the reactor.
The important differences between the processes are in the details of burner design, in the method of syngas cooling, and in soot handling.
Processes suitable for the gasification of liquid feeds can be used with very little modification for the partial oxidation of natural gas or other gaseous feedstocks. Typical differences include the design of the feed-preheat train and the burner. The main process difference is that very little carbon is formed (a few hundred ppm mass instead of values of about 0.5-1% mass) and that the carbon is free of metals, both of which simplify the soot capture and management substantially. And, of course, the gas quality is different, reflecting the C/H ratio of the feed. In the case of sulfur-free feeds, it may also be necessary to review special corrosion issues such as metal dusting.
For this reason, no specific, detailed description of gaseous feed processes is made. Where differences from oil gasification, such as those described above, are worthy of note, these are discussed as part of the relevant oil gasification technology.