三倍浓缩顺流低温多效海水淡化工艺的模拟与优化

Simulation and Optimization of Triple-concentrated Cocurrent Low Temperature Multi-effect Seawater Desalination Process

在海水淡化装置排放盐水资源化利用的条件下,提高盐水浓度成为一种优选的处理方式。以各效蒸发器均能避免形成硫酸钙垢为前提,借助PROII流程模拟软件,计算出已有大型逆流、平流低温多效海水淡化装置的最大浓缩倍率均约为2.1倍。建立大型装置顺流工艺模型后,其最大浓缩倍率可达3倍,为此提出三倍浓缩顺流新工艺。在此基础上,对蒸发器效数、海水预热器数量、蒸汽喷射器抽气位置等参数进行模拟优化,结果表明优化后的排出盐水浓度为10%,设计造水比为16,并考察了热损失、喷射系数、预热器热端温差对造水比的影响。另外,通过1 000 m^3/d中试装置的实际运行,验证了模型的可靠性以及新工艺运行的稳定性。

Under the condition that discharged brine from a desalination plant is reused, increas- ing the brine concentration is a preferred treatment method. The experiment was carried out under the premise that each effect evaporator could avoid the formation of calcium sulfate deposit, and it was found that the maximum concentration ratios of existing large countercurrent and crosscurrent low temperature multi-effect seawater desalination plants were both about 2. 1 times by using PROII process simulation software. A concurrent process model was established for a large plant, and its maximum concentration ratio was up to 3 times. So, a new triple-concentrated process was put forward. On the base of this, the number of evaporator, effect, seawater preheater and steam ejector position were simulated and optimized. Under the optimized conditions, the discharged brine concentration was 10% and the design gained out- put ratio （GOR） was 16, and the influence of heat loss, ejection coefficient and preheater temperature difference at the warm end on GOR was investigated. In addition, the reliability of the model and the sta- bility of the new process was verified through the operation of a 1 000 m3/d pilot plant.