(87d) A Preliminary Study of Feasibility of Mechanical Vapor Recompression of Steam Carbon Dioxide Using Diaphragm Compressor for Energy Conservation in Carbon Capture

Energy consumption in carbon dioxide removal by using chemical solvents is the main point of concern due to the difference in operating conditions of the absorber and stripper besides the endothermic heat of desorption of chemical combined carbon dioxide in the stripper. The stripped gases leaving the stripper at about 105 C and 1 atm (g) contain uncondensed stripping steam to the extent of 50 vol%. The latent heat of the stripper outlet gases is normally rejected to cooling water. As an alternative , mechanical vapor recompression of the above gases to a high pressure around 30 bar (g) or more can facilitate recovery of thermal energy available in the steam by passing the compressed gases through the condensing coils of the reboiler to generate fresh stripping steam from the lean solvent. The main concern to be addressed in this method is the corrosiveness of the stripper outlet gases due to the presence of moisture. This can be taken care by preheating the gases to a temperature level above the dew point of the gas mixture and then compressing it . In the present work, a two stage metal diaphragm diaphragm compressor manufactured by Fluitron Inc, Pa, USA has been selected for study for pilot plant level investigation at IIT, Delhi. The compressor has a capacity to compress 1000 lpm of a 50% steam-carbon dioxide mixture at 105 C and 1 bar (g) to a pressure of 30 bar (g). From the preliminary results obtained in the present work, it appears feasible to compress a gas mixture containing steam and air or carbon dioxide by implementing appropriate preheating, temperature controls, materials of construction and safety measures. Tables 1-6 show some preliminary results obtained in the present work.