A POX on syn

A way to convert natural gas into raw materials for the chemical industry and generate power as a by-product could lead to more environmental benign manufacturing processes.

Making synthesis gas - a blend of hydrogen and carbon monoxide - is a key step in turning natural gas or biomass into bulk chemicals, such as acetic acid, methanol, oxygenated alcohols, isocyanates, and ammonia, which are the feedstock of the global chemical industry. Synthesis gas can also be converted into synthetic diesel fuel. In the conventional process of synthesis gas production, a catalyst and heat are required, which itself requires energy.

Bogdan Albrecht of Daf Trucks N.V. and his colleagues suggest that an alternative heat generating reaction that uses steam and pure oxygen to convert methane into synthesis gas would be far more efficient. The synthesis gas produced would emerge from a POX (partial oxidation) reactor at high temperature and pressure and could be used to drive a gas turbine for power generation.

The researchers have carried out an analysis of the various approaches to producing synthesis gas. The conventional method uses more energy than is released but produces relatively large amounts of synthesis gas. In contrast, two approaches POX, and Autothermal Reforming (ATR) use less energy but produce slightly less synthesis gas. However, the synthesis gas produced by POX is at a much higher temperature and pressure than that from either of the other two methods and so a POX plant can deliver ten times more power and has much lower exergy losses than any other approach. Exergy is the maximum amount of work that can be extracted from a system.

The team explains how this excess power can be used to drive a gas separation system for feeding the raw materials into the synthesis gas plant. They also point out that their prototype design is far more compact than steam turbine systems currently used in synthesis gas production.