Influence of thin juice pH management on thick juice color in a factory utilizing weak cation thin juice softening

摘要

In beet sugar factories utilizing weak cation thin juice softening, soda ash addition to thin juice is utilized to pre-soften the juice to a suitable feed hardness for supply to the weak cation reactors. Generally, there is addition of 50% caustic solution downstream of the weak cation reactors to counter the effect of H+ bleed from the freshly regenerated weak cation resin during the reactor service cycle. If not precisely controlled, the post-reactor re-alkalization of the thin juice may result in over-alkalization of thin juice leading to pH rise in evaporation and an associated color rise in the juice during evaporation. The subject investigation was undertaken for the purpose of optimizing the pre-softening of thin juice while also achieving overall optimum pH management thus avoiding juice over-alkalization and the resulting associated color rise in process juices during juice concentration. A means of pre-alkalization control was developed and implemented satisfying both the pre-softening and the overall juice alkalization requirements leading to the complete elimination of the use of liquid caustic for post-reactor re-alkalization and the elimination of excessive color rise in evaporation. Optimum juice pH targets for minimum color rise in concentration are identified resulting in minimum thick juice color and invert concentration while meeting the competing juice processing requirements for the production of soft thin juice.%En las fabricas de aziicar de remolacha que ablandan el jugo liviano por cationes debiles, se emplea la adicion de sosa al jugo liviano para pre-ablandarlo, hasta una dureza conveniente, para su suministro a los reactores de cationes debiles. Generalmente se adiciona una solucion caustica al 50%, corriente abajo de los reactores de cation debil para compensar el efecto de la liberacion de H+ de la resina de cation debil, recientemente regenerada en el ciclo de servicio del reactor. Si no se controla precisamente la re-alcalinizacion post-reactor del jugo liviano, podria resultar en una sobre-alcalinizacion de este jugo lo que llevaria a una suba de pH en la evaporacion y a una suba asociada del color del jugo durante la evaporacion. La investigacion del tema se llevo a cabo con el proposito de optimizar el pre-ablandamiento del jugo liviano, asi como un manejo global optimo del pH, evitando la sobre-alcalinizacion del jugo y la suba asociada de color en los jugos durante su concentracion. Se desarrollo e implemento una forma de control de la pre-alcalinizacion que satisface tanto los requerimientos del pre-ablandamiento como de la alcalinizacion global del jugo, y que llevo a una eliminacion del uso de solucion caustica para la re-alcalinizacion post-reactor y a la eliminacion de la excesiva suba de color en la evaporacion. Se identificaron los objetivos optimos de pH para una suba minima de color durante la concentracion que resultan en un color y una concentracion invertida minimos en el jugo espeso en tanto que cumplen con los requerimientos antagonicos de proceso para la produccion de jugo liviano blando.