【作者】 梁林；

【导师】 吉洪湖；

【作者基本信息】 南京航空航天大学 ， 工程热物理， 2013， 博士

【摘要】 在印染、化工、造纸、医药和农药等生产过程中会产生大量高浓度含盐废水，有些废水中所含无机盐还具有回收利用的价值，直接排放将导致水环境污染和资源浪费。常规的多效蒸发可以对该类废水进行处理和回收，却存在着能量消耗高、配套设备多、运行费用高等问题。因此，研究一种能耗少、运行费用低且结构紧凑的高浓度含盐废水处理方法具有一定的现实意义。为此，本文以降低能耗为目标，提出了处理高浓度含盐废水的两级机械蒸汽再压缩(Mechanical Vapor Re-compression，MVR）的方法，设计了系统流程，建立了系统热力分析平台；设计了系统关键设备结构，构建了工程实验系统装置并实施了工程化的实验研究；最后，对系统开展了综合性能评价分析。首先，对现有含盐废水处理技术及高浓度含盐废水特征进行了分析，提出了适合处理高浓度含盐废水的两级MVR方法并设计了具体的工艺流程，构建了系统中主要设备的模型及系统的计算平台并用已公开的数据加以了验证；借助该平台对两级MVR系统及其参比的单级MVR和三效蒸发系统进行了分析，获得了两级MVR系统及参比系统的整体热力性能，所提系统的性能系数和节能率等指标均较参比系统有显著提高，与传统三效相比可节省能耗75.8%；同时分析了一级排出浓度、蒸发温度、传热温差等重要参量对两级MVR系统能耗的影响规律。基于以上理论分析，采用遗传算法对加热器的结构进行了基于综合成本目标的优化设计；设计了深入内部的轴向进料闪蒸器及其结构；建立了针对实际工程应用的两级MVR系统装置，该系统置于某染料生产企业用于处理生产过程中产生的高浓度硫酸铵废水，据此研究了系统工程状态下实际运行性能，并与模拟结果进行了对比分析。研究表明，系统实际单位能耗为53.8kWh/t实现了能量消耗低的目标；实际运行结果与模拟结果基本相符，这说明本文建立的模拟和设计模型是可靠的。实验效果表明，系统回收了硫酸铵，排放出了净水，达到了对高浓度废水处理的要求。建立了考虑废水中盐分影响的两级MVR系统的火用分析模型，采用上述实验得到的数据，对系统进行了实际状态下的火用分析，获得了系统的火用损失分布状况，及压缩比、蒸发温度和一级排出浓度对系统火用效率的影响规律，并依据分析给出了改进措施。随后，基于以上获得的系统各物流火用，引入热经济学结构理论，构建了两级MVR系统热经济学模型，分析了系统的热经济学成本及其分布，并研究了系统内、外部参量对系统热经济学成本的影响规律。分析结果表明，较之单级MVR系统，本文所述系统的火用效率提高13.4%，单位产品成本降低6.8%，两级MVR系统的综合性能优势明显；内部操作温度变化对系统各组元热经济学成本的影响大于一级排出浓度对各组元的影响；外部电力价格对各组元热经济学成本的影响要大于设备投资对相应组元的影响。本文为处理高浓度含盐废水提供了一种低能耗的思路及方法，所获得的研究结果对MVR技术的运用发展具有重要的理论和工程应用价值。更多还原

【Abstract】 Great deals of high concentrations inorganic salts wastewater are discharged by industries ofdyeing and finishing, chemical engineering, paper making, pharmaceuticals and pesticides. Inorganicsalts contained in some wastewater have the value of recycling. If these wastewater are directlydischarged, it will lead to water pollution and waste of resources. There are some problems forconventional multi-effect evaporation, which can treat this kind of waste water, such as high energyconsumption, more corollary equipment and high operating costs. Therefore, it is necessary to developa method which is low energy consumption, low operating costs and compact, to treat highconcentration saline wastewater.In this paper, a method of two-stage mechanical vapor recompression (MVR) was proposed, andthen designed the system process, simulated and analyzed the system, carried out experimental studyand evaluated the performance of the system.First, this paper analyzed the existing salinity wastewater treatment technology andcharacteristics of high concentrations of saline wastewater and put forward a new two-stagemechanical vapor recompression evaporation method. The system process corresponding to the newmethod was designed. The model of main equipment and the computing platform of the system wereestablished and verified by public data. Systems of two-stage MVR, one-effect MVR and three-effectevaporation were analyzed. Overall thermal performances were discussed. Results show thatcompared to the reference system, coefficient of performance and energy efficiency of the new systemis higher. And it can save about75.8%of energy compared with the three-effect evaporation. At thesame time, the influence of the parameters (such as one-stage discharge concentration, evaporationtemperature and temperature difference) on energy consumption of the two-stage MVR system isinvestigated.Following above theoretical analysis, the heater structure is optimized and designed usinggenetic algorithms with the minimum cost targets. The flasher and its structure with feeds from axiswere designed. Then the actual two-stage MVR system device was build which is placed in a dyemanufacturer for the treatment of high concentration of ammonium sulfate wastewater. Actualoperating performances of system at industrial state were studied. The results show that the actualenergy consumption of system is about53.8kWh/t realized the low energy consumption target; theresults of simulation and experiment are in good agreement which shows that the simulation and design model is reliable. The experimental results show that the system recovers ammonium sulfateand discharges clean water, and reaches the treatment requirements.The exergy analysis model of two-stage MVR system considering the influence of salt in thesolution was established. Using above experimental data, the exergy analysis of system had beencarried out at the actual condition. The exergy loss distribution and the effect of compression ratio,evaporation temperature and one-stage discharge concentration on exergy efficiency of the system hadbeen obtained. Improvement measures based on the analysis were suggested. Then, based on theabove logistics exergy, the thermal economics structure theory was introduced to build the thermaleconomics model of two-stage MVR system. The economic cost and distribution was analyzed. Also,the influence of internal and external parameters on the system thermal cost economics was studied.Analysis results showed that compared with single-effect MVR system, system’s exergy efficiencydescribed in this article increase by13.4%and the unit product costs decrease by6.8%.So,theadvantages for the comprehensive performance of two-stage MVR system is obvious. the effect ofinternal operating temperature on thermal cost economics of every component is more than the effectof one-stage discharge concentration; The influence of external electricity price on thermal economicscost of every component is greater than the influence of equipment investment.This paper provides a low energy consumption method for treatment the high concentrationsaline wastewater. The obtained results have a certain theoretical and practical reference value forapplication and development of MVR technology.更多还原