(364a) A Process Synthesis Approach to Improving the Efficiency of Coal Fired Power Stations

A large portion of the energy used worldwide originates from fossil fuels. Coal in particular is the major resource for mechanical and electrical power production. The use of coal for power production involves direct combustion of coal for high pressure and high temperature steam generation followed by mechanical work recovery by passing the steam through turbines.

However this process has been proven to be highly inefficient, leading to the loss of the large portion of the coal work potential.

In this work a graphical approach is used to show that most of the inefficiencies lie in the stage of coal combustion. It can be shown that considerable improvement can be made by changing the chemical route for coal combustion; this could result in the production of valuable chemicals in addition to the work produced.

One of the chemical routes explored constitutes partial oxidation of coal combined with the catalytic production of hydrogen, followed by ammonia production. The ammonia can then be oxidised catalytically to nitric oxides for subsequent production of nitric acid and fertiliser. It is shown that each step in this process has a certain amount of work potential which can be recovered through steam production. It is also shown that in addition to the nitric acid production, approximately 10% improvement in work production efficiency can be achieved; compared to the direct coal combustion where only carbon dioxide is produced.

By combining fertiliser manufacture with electricity production one can in principle improve the efficiency of both processes. This is potentially a real win-win situation.