METHOD AND EQUIPMENT FOR ADJUSTING RECIRCULATION FLOW OF OZONE GAS IN BLEACHING OF PULP WITH OZONE

摘要

PURPOSE: To provide a method for controlling re-cycling stream of ozone gas in an ozone pulp bleaching process controlled so as to enable an action of an ozone generator at a sufficient ability in a level of carbon dioxide of a re-cycling stream. CONSTITUTION: This invention specifies a concentration of carbon dioxide in a relating operating range and the maximum concentration is specified to a sufficient ability/optimum efficient action. A specific method containing purging a part of a re-cycling stream, counter-current scrubbing the recycling stream with an alkaline solution and passing the re-cycling stream through an adsorbing material is described for controlling a carbon dioxide concentration. Contaminants entering the system may be reduced by directing the purged re-cycling stream, which is relatively oxygen rich, into a dewatering press where pulp consistency is increased. In the manner, nitrogen surrounding the pulp is displaced by oxygen and thus, does not enter the bleaching/ozone system with the pulp.