(43b) The Effect of Compression and Intercooling On the Composition of a Pulverized Coal Oxycombution Flue Gas

Oxy-fuel combustion uses conventional technology to combust pulverized coal in denitrified air resulting in a flue gas which is primarily CO₂ and water.  Integrated Pollutant Removal (IPR^®) is an NETL patented process that compresses the oxycombustion flue gas to pipeline pressure. The IPR process as it is realized at the Jupiter Oxygen Burner Test Facility is a spray tower (direct-contact heat exchanger) followed by 4 stages of compression with intercooling. The spray tower can be run either with water or with water plus a reagent used to control the pH and precipitate the reactive components of the gas. Latent and sensible heat given up by the processed gas at the cooling steps are partially recovered and in a commercial process could be used to preheat the boiler feed water. A FTIR and a gas chromatograph were used to measure the entering gas composition, the exiting composition as well as the composition at several intermediate points within the IPR system. The experimental results are compared to an ASPEN model of the system. The entering flue gas is approximately 30% water vapor with the remainder mostly CO₂. The gas also contains SO₂, various oxides of nitrogen (mostly from nitrogen in the coal), O₂, CO, HCl and small amounts of other gasses derived from these. The initial spray tower removes much of the water and soluble gasses. More water and soluble gases are removed in each intercooling step until the exit gas is primarily CO₂. The increasing pressure also changes the relative amounts of the different oxides of nitrogen.