多相流蒸发法高浓缩率海水淡化系统的热力学性能分析

建立了顺流进料的多相流蒸发法高浓缩率海水淡化系统的数学模型,考虑了热力损失、压力损失、盐水含量变化引起的温差损失;计算分析了相同淡水产量下固体颗粒体积分数、预热量、首效加热蒸汽温度对系统的影响。结果表明,固体颗粒体积分数和首效加热蒸汽温度对各效蒸发器传热面积影响较大;预热量对生蒸汽耗量影响较大;固体颗粒的加入能够强化传热,减小各效蒸发器的传热面积;在无预热情况下,固体颗粒体积分数为13%时,蒸发器总传热系数比固体颗粒体积分数为3%时可增大6.71%,各效蒸发器传热面积减少4.97%,淡水成本减少1.22%。     

海水淡化与水源热泵联合系统性能与成本研究

提出了低温多效海水淡化装置与水源热泵联合系统技术,建立了联合系统数学模型,并利用MATLAB编制程序进行了求解,分析了末效二次蒸汽温度对联合系统热力性能与成本的影响,并且与低温多效海水淡化系统进行了成本比较。计算结果表明:在文章的计算范围内,随着末效二次蒸汽温度的升高,加热蒸汽量减少,蒸发器总传热面积增大,驱动蒸汽量减少,供热水量减少,综合效果是淡水成本增加。其他参数相同的情况下,与低温多效海水淡化系统相比,联合系统的淡水成本节省11.68%。     

大型低温多效蒸馏海水淡化装置中试研究

基于低温多效蒸馏海水淡化中试装置,研究了工作蒸汽流量、TVC抽汽温度、物料水流量等运行操作条件以及换热管倾斜布置对装置整体性能的影响.结果表明:调整工作蒸汽流量是控制装置淡水产量的主要手段,装置的淡水产量随工作蒸汽流量的增加而增大;TVC抽汽温度升高有利于提高淡水产量和造水比;装置的淡水产量和造水比均随物料水流量的增加呈现下降的趋势,但下降幅度不大;在5‰的斜率内换热管倾斜布置还是水平布置对淡水产量几乎没有影响.     

低温多效蒸发海水淡化系统热力分析

建立了喷射器低温多效蒸发海水淡化系统的数学模型,计算分析了各种温度损失随温度的变化,并研究了顶值盐水温度、蒸发器效数和动力蒸汽等参数对系统的造水比和生产单位质量淡水所需传热面积的影响。结果表明各种温度损失在末效蒸发器内显著增加;喷射器低温多效蒸发系统的热力特性明显优于多效蒸发系统;通过增加顶值盐水温度、蒸发器效数和动力蒸汽温度,可以实现系统的优化运行。     

吸收式与热压缩式海水淡化系统比较

提出了热压缩多效蒸发海水淡化和吸收式热泵多效蒸发海水淡化两种系统,建立了系统计算数学模型。分析了不同末效二次蒸汽温度对这两种系统的的影响,并且对这两种系统进行了性能与经济性比较。计算结果表明:随末效二次蒸汽温度的升高,两种系统的蒸发器总传热面积均增加,前者所需动力蒸汽量减少,后者所需动力蒸汽量变化不明显,综合效果是前者淡水成本变化不明显,后者淡水成本明显增加。在本文的计算范围内,其它参数相同的情况下,与前者相比,吸收式热泵多效蒸发海水淡化系统经济性较好,淡水成本可减少9.23%。     

低温多效蒸发海水淡化系统性能的实验研究

针对大型海水淡化工程设计关键技术,依托1 t·d-1低温多效蒸发海水淡化实验平台,考察了装置运行性能的稳定性,系统地研究了不同海水进料量及首效蒸汽温度对造水比、浓缩比和产品水质等关键参数的影响。结果表明:在实验条件范围内,随着首效蒸汽温度提高,海水的浓缩比先减小后增加,而首效温度对造水比的影响较小;在一定首效温度下,浓缩比随着海水进料量的增大而减小,而造水比随海水进料量的增大而增大。在实验范围内,产品水的固体总溶解浓度均低于5 ppm。小型海水淡化平台关键技术的实验研究为低温多效海水淡化系统在扩大化中的设计优化提供了参考和借鉴。     

多效蒸馏海水淡化技术的发展及应用

多效蒸馏是近几年发展起来的一种新型的海水淡化技术,其原理是加热后的海水流经多个串联运行蒸发器,前一效蒸发的二次蒸汽作为下一效的加热蒸汽,并冷凝成为淡水的过程.多效蒸馏技术可以充分利用电厂余热蒸汽作为热源,这不但解决了淡水紧缺的问题,而且利用了低品位能源.     

基于低温蒸馏-喷雾蒸发集成工艺的海水淡化

考察了利用低温蒸馏-喷雾蒸发集成工艺进行海水深度淡化的可行性,使用喷雾蒸发技术深度浓缩蒸馏淡化过程排出的浓盐水,并将余热用于驱动蒸馏过程。考察了蒸馏柱进液量、浓盐水喷雾量、加热空气温度及流速对淡水产量的影响。结果表明,较高的加热空气温度有利于淡水产量的提高,而为获得较高的淡水产量,加热空气流速、浓盐水喷雾量以及蒸馏柱进液量则应控制在一定的范围之内,即10—15 m3/h,0.4—0.6 kg/h和0.8—1 kg/h。对于该集成装置,蒸馏柱淡水产量、总淡水产量及淡水产量与输入淡化系统的蒸汽当量之比(造水比)分别可达5 kg/(h.m2),1 kg/h及1.2,回收率可以达到70%以上。     

无辅助热源太阳能海水淡化系统运行性能分析

建立了无辅助热源的真空管集热太阳能低温多效海水淡化系统数学模型,利用MATLAB语言编制程序进行求解,并进行了运行性能分析。在本文的计算范围内,结果表明:随着启动温度增大,水箱水温升高,产水速率提高,系统运行时间缩短,日总产水量变化不明显;随着水箱热水流量增加,产水速率升高,系统运行时间缩短,日淡水产量和日闪蒸蒸汽量先明显增大后缓慢增大。     

低温多效海水淡化混流效组系统优化与分析

建立了多个混流点的混流效组低温多效蒸发(LT-MED)海水淡化数学优化模型,将海水视为盐和水的混合物,其焓表达为温度的函数,降低优化模型的非线性程度,使其易于收敛。以比传热面积为优化目标分析了不同流程和参数对系统的影响。结果表明,在喷淋密度为30~80 g/(m·s)时,多混流点系统的造水比与单混流点系统相比提高了12.1%,比传热面积降低了8.4%,优化流程为5效+2效+2效组合;提高首效加热蒸汽温度可有效的减少换热面积,降低制水成本,对系统的造水比影响不大;增加系统效数,可以有效提高造水比。各效等面积蒸发方案造水比比不等面积方案略有下降,比传热面积略有增加。模拟结果与文献中相关数据吻合良好,可为低温多效蒸发海水淡化系统工程化设计提供技术支持。     

Simulation and Analysis of a Single‐Effect Thermal Vapor‐Compression Desalination System at Variable Operation Conditions

A mathematical model is developed to analyze a single‐effect thermal vapor compression (TVC) desalination system. The effects of the variation of operation conditions such as the intake seawater temperature and the mass flow rate of cooling water on the system performance are investigated for a specific desalination unit. The system performance is found to decrease when the intake seawater temperature is different from the design value. By adjusting the mass flow rate of cooling water, a better system performance can be obtained when the intake seawater temperature differs from the design conditions. Decreasing the cooling water flow rate to values lower than the design value can lead to a better performance when the intake seawater temperature is lower than the design value, and the system performance reaches a peak point when the cooling water flow rate decreases to a definite level. A better performance can also be obtained by increasing the cooling water flow rate to values higher than design value, when the intake seawater temperature is higher than the design value and the system performance also reaches a peak point when the cooling water flow rate increases to a definite level.     

考虑水需求的水电联产海水淡化系统的优化设计

水电联产不仅能缓解淡水资源不足的问题,而且可有效降低能耗和淡化成本。建立了水电联产系统数学模型,将优化设计描述为一个混合整数非线性规划(MINLP)问题,并采用混合编码的遗传算法进行求解,结果表明,以水定电模式下水电联产系统最优操作模式为发电、多级闪蒸(MSF)和反渗透(RO)三者的集成,且MSF和RO的产水比存在最优值,发电采用背压式蒸汽轮机。随着淡水需求量的增加,联产系统的淡水成本逐渐降低,MSF与RO的产水比呈现出逐渐降低的趋势。     

太阳能直热式多效蒸馏淡化系统热力分析

本文设计了一种太阳能直热式多效蒸馏淡化系统,它将太阳能直热式系统和多效蒸馏系统相结合来淡化苦成水。文中对这一系统进行产水量和蒸发器的热力分析并进行了模拟计算,结果表明当太阳能直热式系统出水温度达到60℃,系统一天的产水量可达40Kg,当多效蒸馏的效数为4时,淡水的成本在5—7元。在太阳能资源丰富而淡水缺乏的地区,使用太阳能直热式多效蒸馏系统是可行的。     

Feasibility study and performance assessment for the integration of a steam-injected gas turbine and thermal desalination system

This study proposes a systematic approach for retrofitting a steam-injection gas turbine (SIGT) with a multi-effect thermal vapor compression (METVC) desalination system. The retrofitted unit's product cost of the fresh water (RUPC) was used as a performance criterion, which comprises the thermodynamic, economic, and environmental attributes when calculating the total annual cost of the SIGT–METVC system. For the feasibility study of retrofitting the SIGT plant with the METVC desalination system, the effects of two key parameters were analyzed using response surface methodology (RSM) based on a central composite design (CCD): the steam air ratio (SR) and the temperature difference between the effects of the METVC system (?T_METVC) on the fresh water production (Q_freshwater) and the net power generation (W_net) of the SIGT–METVC system. Multi-objective optimization (MOO) which minimizes the modified total annual cost (MTAC) and maximizes the fresh water flow rate was performed to optimize the RUPC of the SIGT–METVC system. The best Pareto optimal solution showed that the SIGT–METVC system with five effects is the best one among the systems with 4–6 effects. This system under optimal operating conditions can save 21.07% and 9.54% of the RUPC, compared to the systems with four and six effects, respectively.     

不同流程下低温多效海水淡化系统热力性能研究

建立了串联无预热、串联预热、并联无预热、并联预热4种流程下的低温多效海水淡化系统数学模型,并利用MATLAB语言编制程序进行了求解,比较了不同流程对系统热力性能的影响。计算结果表明：当海水淡化系统为6效,在其他参数相同的情况下,与无预热流程相比,预热流程所需的加热蒸汽量较少,造水比较大,传热总面积较小,冷却海水量小。与串联流程相比,并联流程所需的加热蒸汽量较少,造水比较大,传热总面积较小,冷却海水量小。综合结果是并联预热流程的热力性能最优。     

基于热力蒸汽压缩蒸发的油田污水淡化系统及分析

针对油田污水污染物成分复杂、污染性强不适合膜法脱盐的特点和淡水消耗与余热资源共存的实际,提出用热力蒸汽压缩（TVC）蒸发技术对油田污水进行集中脱盐处理的技术方案。建立了基于TVC的油田污水脱盐系统的工艺流程设计计算模型,系统分析了蒸发温度等主要运行参数的影响。结果表明：系统性能系数随蒸发温度的降低而增大,降低蒸发温度有助于减少主蒸汽消耗,但所付出的代价是总传热面积和污水泵流量的增大;TVC系统的热力学完善度相对较低,与多效蒸发系统联合使用是改善系统性能的基本途径之一。尽管如此,对于油田生产来说,当存在合适的余热资源时,简单的单效TVC系统仍不失为合理的技术方案。     

加热器和冷却器传热温差的优化

分别以冷却器冷却水出口温度和加热器加热蒸汽温度为决策变量,以总费用为目标函数,提出了确定加热器蒸汽最佳湿度和冷却器冷却水最佳出口温度即最佳传热温差的数学模型,并结合实例说明了计算方法。     

Steady-State Analysis of the Multiple Effect Evaporation Desalination Process

Mathematical modeling of the multiple effect evaporation (MEE) desalination process has been carried out to determine the effects of the important design and operating variables on the parameters controlling the cost of producing fresh water. The model assumes the practical case of constant heat transfer areas for both the evaporators and feed preheaters in all effects. In addition, the model considered the impact of the vapor leak in the venting system, the variation in thermodynamic losses from one effect to another, the dependence of the physical properties of water on salinity and temperature, and the influence of noncondensable gases on the heat transfer coefficients in the evaporators and the feed preheaters. The modified fixed-point iterative procedure is used to solve the large number of highly nonlinear equations describing the MEE desalting system. The algorithm consists of 10 calculation blocks and 6 logical blocks. The algorithm is implemented using L-A-S computer aided language. Results show that the heat transfer coefficients increase with the boiling temperature. Also, the heat transfer coefficient in the evaporator is always higher than that in the feed preheater at the same boiling temperature. The plant thermal performance ratio is nearly independent of the top brine temperature and strongly related to the number of effects. The specific heat transfer area increases by raising the number of effects and reducing the top brine temperature. The effect of the top brine temperature on the specific heat transfer area is more pronounced with a larger number of effects. The required specific heat transfer areas at a top brine temperature of 100°C are 30.3% and 26% of that required at 60°C when the number of effects are 6 and 12, respectively. The specific flow rate of cooling water is nearly constant at different values of top brine temperature and tapers off at a high rate as the number of effects is increased. Two correlations are developed to relate the heat transfer coefficients in the preheater and the evaporator to the boiling temperature. Design correlations are also developed to describe variations in the plant thermal performance, the specific heat transfer area, and the specific flow rate of cooling water in terms of the top brine temperature and the number of effects.