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Large Volume Inorganic Chemicals - Ammonia ... - ammk-rks.net

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Chapter 88.4.2 CO 2 stripping processDescriptionTable 8.14 gives an overview of a total recycling CO 2 stripping process. A key feature of thistechnology is the removal of most of the residual carbamate and NH 3 from the reaction solutionby stripping with CO 2 at high pressure. In comparison with conventional processes, this savesconsiderable amounts of energy for decomposition at low pressures and recompression forrecycling to the process.Process sequenceSteps and conditionsNH 3 /CO 2 ratio2.8, CO 2 is fed via the HP stripperReactorTemperature 180 ºCPressure140 barStripping with CO 2and recycling athigh pressurePurge gas(from reactor)HP stripperHP condensertreated in HP scrubber, LP scrubber (4 bar), NH 3 solutions are recycledCarbamatedecomposer(rectification)Pressure3 barCarbamaterecyclingNH 3 recyclingCondensation, exhaust gas treated with scrubbingCondensation, NH 3 buffer, NH 3 solution is recycledVacuum cystallisation, condensate treatment (desorber/hydroliser/desorber)Solidification andfinishingCentrifugationDrying, cyclone, acidic scrubbing for exhaust gas treatmentMeltingPrilling or granulationTable 8.14: Example for a total recycling CO 2 stripping process[121, German UBA, 2001]Achieved environmental benefits• enables almost complete raw material recovery• energy savings in comparison with conventional processes.Cross-media effectsNone believed likely in comparison with other urea production processes.<strong>Large</strong> <strong>Volume</strong> <strong>Inorganic</strong> <strong>Chemicals</strong> – <strong>Ammonia</strong>, Acids and Fertilisers 339

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