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首页> 外文会议>International Chemical Recovery Conference v.1; 20040606-20040610; Charleston,SC; US >Prediction Of Crystal Species Transition In Aqueous Solutions Of Na_2co_3 And Na_2so_4 And Kraft Black Liquor
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Prediction Of Crystal Species Transition In Aqueous Solutions Of Na_2co_3 And Na_2so_4 And Kraft Black Liquor

机译：Na_2co_3和Na_2so_4和牛皮纸黑液水溶液中晶体形态转变的预测

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Many of the fouling problems that occur in black liquor evaporators are the result of crystallization of Na_2CO_3 and Na_2SO_4. Shi (2002) measured the compositions of Na_2CO_3 and Na_2SO_4 in water and in black liquor at the onset of crystallization during evaporation. He also measured the composition of the first crystals produced for a range of relative concentrations of Na_2CO_3 and Na_2SO_4. The crystals that produce scale are the sulphate-rich, double salt burkeite, and a carbonate-rich double salt referred to as dicarbonate. We used Shi's data to obtain the apparent changes for crystallization of burkeite and dicarbonate as a function of the relative concentrations of Na_2CO_3 and Na_2SO_4 in solution. The apparent equilibrium relationships obtained were solved with the constraints of Shi's experimentally determined relationship between solution and crystal composition and the conservation of mass and charge. The resulting model predicts the changing compositions of the sodium salts in solution and the changing composition of the crystals formed as evaporation proceeds. This model can also be used for predicting the solubility limit of these sodium salts in black liquor. The compositions of Na_2SO_4 and Na_2CO_3 predicted by the model are slightly different than measured equilibrium values due to some constraints. However with regard to understanding and controlling fouling during evaporation of black liquor, the compositions at the onset of crystallization are the ones of most interest.
机译：黑液蒸发器中发生的许多结垢问题是Na_2CO_3和Na_2SO_4结晶的结果。 Shi（2002）测量了蒸发过程中结晶开始时水和黑液中Na_2CO_3和Na_2SO_4的组成。他还测量了Na_2CO_3和Na_2SO_4相对浓度范围内产生的第一批晶体的组成。产生水垢的晶体是富含硫酸盐的复盐硼碳酸盐和富含碳酸盐的复盐，称为重碳酸盐。我们使用Shi的数据获得了溶液中Na_2CO_3和Na_2SO_4的相对浓度的函数，表明burkeite和碳酸氢盐的结晶存在明显的变化。通过Shi的实验确定的溶液与晶体组成之间的关系以及质量和电荷守恒的约束，解决了获得的表观平衡关系。所得模型预测溶液中钠盐的组成会发生变化，并且随着蒸发的进行，所形成的晶体的组成也会发生变化。该模型还可用于预测这些钠盐在黑液中的溶解度极限。由于某些约束，模型预测的Na_2SO_4和Na_2CO_3的组成与测得的平衡值略有不同。然而，关于理解和控制黑液蒸发过程中的结垢，最开始关注的是结晶开始时的组合物。

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