Coal Based Polygeneration with Co2 Capture for Power and Urea Production - Possible Improved Schemes

Polygeneration is the process of combining multiple utility outputs with one or more input(s) in a single integrated unit. The integration is towards a higher energy efficiency as well as environment friendliness. Fossil fuels, specifically coal, will continue as the prime source of energy for a considerable future. However Carbon-dioxide emissions from coal based plants has serious „climate change‟ effects. In this paper the Carbon-dioxide produced from the coal is utilized for production of ureain several well integrated and power-dominated polygeneration schemes. Power generation isby combined gas-steam power cycle. Other utilities of the polygeneration are utility heat and in some cases production of sulphuric acid. The utility heat obtained during urea production is proposed to be utilized by either heating the feed water in the steam cycle or by producing process steam. Different alternative schemes with similar utility outputs are discussed for relative advantages and disadvantages. Conceptualized schemes are not only CO2 neutral though using coal but also compact and efficient with respect to same utility outputs in separate plants. Schematics show that depending upon one upstream process (say, gasification), downstream processes (say, carbon capture or urea production) may be changed according to their compatibility and state points may also vary for individual processes. Different utilities will also vary accordingly.