基于机械蒸汽压缩蒸发的油田污水脱盐系统及分析

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,提出用机械蒸汽压缩蒸发（MVC）技术对油田污水进行脱盐处理的技术方案。建立了基于MVC的油田污水脱盐系统的工艺流程设计计算模型,系统分析了降膜蒸发器传热温差、油田污水温度和蒸发温度的影响。结果表明：传热温差是影响系统装置规模和运行电耗的控制因素,减小传热温差可以明显降低压缩机比电耗,付出的代价是系统比传热面积的增大;MVC系统的热力完善度高,无废热排放,油田污水温度越高,系统比传热面积减小;在其他条件允许的条件下,提高系统的运行温度有利于改善系统的性能。     

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。     

热泵蒸发装置的技术方案分析

热泵蒸发技术具有能耗低、结构简单等特点。给出了热泵与蒸发单元相结合的五种典型技术方案,即蒸汽直接压缩式热泵蒸发装置、热泵真空多效蒸发装置、热泵膜蒸馏装置、空气循环热泵蒸发装置、蒸汽喷射式热泵蒸发装置。分别介绍了这些热泵蒸发装置的基本构成、工作过程和主要特点,可为工程实践中选用适宜的热泵蒸发装置提供较好的参考。     

大型低温多效蒸发海水淡化装置传热过程热力损失分析

基于低温多效蒸发海水淡化装置的各种阻力和海水沸点升高（BPE） 关联式,计算了海水淡化装置中流动阻力、海水沸点升高等造成的传热过程热力损失,分析了各项热力损失在各效蒸发/冷凝器中的分布、随蒸发/冷凝器数量的变化规律等。结果表明：产水量、浓缩比和加热蒸汽温度等参数均保持不变的前提下,总的热力损失随着装置的蒸发/冷凝器数量而增加;BPE引起的热力损失占最大比例,但流动阻力引起的热力损失不可忽略。通过对海水淡化装置热力损失的分析,提出了低温多效蒸发海水淡化装置“小温差、低流阻、饱和态、高敏感”的工作特征理论。     

大型低温多效蒸发海水淡化装置传热过程热力损失分析

基于低温多效蒸发海水淡化装置的各种阻力和海水沸点升高(BPE)关联式,计算了海水淡化装置中流动阻力、海水沸点升高等造成的传热过程热力损失,分析了各项热力损失在各效蒸发/冷凝器中的分布、随蒸发/冷凝器数量的变化规律等。结果表明:产水量、浓缩比和加热蒸汽温度等参数均保持不变的前提下,总的热力损失随着装置的蒸发/冷凝器数量而增加;BPE引起的热力损失占最大比例,但流动阻力引起的热力损失不可忽略。通过对海水淡化装置热力损失的分析,提出了低温多效蒸发海水淡化装置"小温差、低流阻、饱和态、高敏感"的工作特征理论。     

印染丝光淡碱液MVR蒸馏系统研究

基于NaOH碱溶液泡点温度随浓度变化明显的特性,建立单效两级压缩、双蒸发器分级压缩和二效两级压缩3种MVR蒸馏系统,并利用Aspen Plus软件进行了仿真研究。结果表明,固定工况下,双蒸发器分级压缩系统存在最优蒸汽压缩分配方案使系统新鲜蒸汽消耗量最低;二效两级压缩MVR系统运行费用低于单效两级压缩和双蒸发器分级压缩MVR系统,且蒸发水量越大优势越明显,但蒸汽压缩机总体积流量大于双蒸发器分级压缩系统,实际应用时需综合考虑蒸汽压缩机的投资成本进行系统选择。     

膜蒸馏处理高盐废水过程能量回收技术现状

介绍了现有高盐废水处理技术包括多效蒸发、多级闪蒸、机械蒸汽压缩和反渗透等技术的原理、优势和应用局限性。相比现有的技术,膜蒸馏技术在处理高盐废水中的具有一定优势,经过多年研究,膜蒸馏技术取得很大发展,特别是在高盐废水处理领域,本文对膜蒸馏过程现有的能量回收技术现状进行详细介绍和讨论,指出实现膜蒸馏过程能量回收对于降低高盐废水处理成本具有重要意义。     

利用机械式蒸汽再压缩以降低蒸馏能耗

螺杆式压缩机能够对湿润蒸汽进行压缩、同时,在压缩过程中,流体始终处于均质与热力平衡的状态之中。因此,使用这种装置,可望提高蒸馏系统的能效。     

高含盐废水零排放蒸发结晶技术进展

随着水资源的日益短缺,实现工业废水零排放是大势所趋,用于高含盐废水零排放的蒸发结晶技术的核心是蒸发。介绍了多效蒸发、热力蒸汽再压缩蒸发、机械蒸汽再压缩蒸发、降膜式机械蒸汽再压缩循环蒸发等的工艺流程、技术特点、存在的问题及其应用情况,指出不同企业应根据实际情况,选择适宜的蒸发结晶工艺,在最大限度地对废水进行回用的基础上实现废水零排放,为可持续发展作贡献。     

MVR蒸发与多效蒸发技术的能效对比分析研究

针对氨基酸溶液蒸发浓缩生产过程的高能耗问题,提出一种新的基于机械蒸汽再压缩蒸发浓缩节能工艺及装置.介绍了机械蒸汽再压缩蒸发浓缩节能新工艺的工作原理,以15 t/h氨基酸的蒸发浓缩为工程实例,对采用MVR蒸发技术和传统的多效蒸发技术进行了能效对比分析研究.研究结果表明,采用MVR蒸发技术比传统的多效蒸发技术每年可节省783.14万元的加热蒸汽费用及20.12万元的蒸汽冷凝水费用,相当于节省了85.7％的标准煤.另外,在相同的蒸发条件下,MVR蒸发装置所需热量为三效蒸发的24％.     

Seawater integrated desalination plant without brine discharge and powered by renewable energy systems

Environmental effects are one of the main concerns of massive desalination facilities. To reach the objective of no brine discharge the salt from seawater must be completely separated and obtained as a secondary and valuable product. If no CO₂ emission increase is desired, the power source must be a combination of renewable energy systems (RES). This paper presents an analysis of an integrated desalination scheme consisting of two sequential systems: a multi-effect distillation (MED) plant and a mechanical vapour compression (MVC) system based on evaporator equipment. The energy is obtained by several wind turbines (WT) and a thermal solar collector (TSC) field. Separation of salt and water is achieved in a coupled multi-effect distillation-mechanical vapour compression (MED+MVC) two step process. The MED stage is driven by thermal solar collectors, whereas the energy consuming mechanical compression of the vapour (MVC) is fuelled by wind-powered turbines. Interestingly, the final products of this process are dry salt and fresh water. Such a system has been designed and dimensioned for a throughput of 100 m³/h of desalted water A preliminary study of the investment, amortization and exploitation costs of a combined MED+MVC+WT+TSC installation with these dimensions has been done. The price of desalted water, after considering the profits due to the sale of salt and electricity has been estimated at 0.59 ?/m³. If the initial investment has a 35% subsidy, a final price of 0.41 ?/m³ could be ensured, which is near the price associated to conventional energy sources. An outline of the solar collector system and the technical requirements of the wind turbines in needed to meet the energy demand of the MED+MVC system are also included.     

Analysis of water production costs of a nuclear desalination plant with a nuclear heating reactor coupled with MED processes

A nuclear heating reactor (NHR) was designed with the required inherent safety and simplified design features. Power capacity of the NHR-200 (200 MW(th), with steam production of 380 t/h) is compatible with reasonably sized desalination plants. Thermal-hydraulic parameters of the produced steam (2.4 bar and 124°C) are suitable for coupling with distillation processes. Economic competitiveness of the NHR desalination plant is the key point to which the public and decision-makers are paying good deal of attention. Coupling of the NHR with selected MED processes and design parameters of an integrated desalination plant are described. Results of analyses of water production costs are presented as well. Based on the economic evaluation, the average energy cost of the nuclear plant may reach 5.44 $/t of steam, and the provided water production cost may reach 0.72 $/m³ and 0.76 $/m³ for coupling with HT–VTE–MED and LT–HTE–MED processes, respectively.     

Coupling of nuclear heating reactor with desalination process

A seawater desalination plant using a nuclear heating reactor (NHR) coupled with the multi-effect distillation (MED) process was developed by the Institute of Nuclear Energy Technology, Tsinghua University, China. The seawater desalination plant was designed to supply potable water demand to some coastal location or island where both fresh water and energy sources are severely lacking. The NHR design possesses intrinsic and passive safety features, which was demonstrated by the NHR-5 experiences. The intermediate circuit and steam circuit were designed as the safety barriers between the NHR and MED desalination systems. With the power range of the heating reactor within 10 to 200 MWt, the desalination plant could provide 8,000 to 160,000 m³/d of potable water of appropriate quality. The design concept and parameters, safety features, and comparative investigation of coupling schemes are presented in the paper.     

多效蒸发海水淡化系统可行域时变分析与全周期操作优化

能耗过高制约了多效蒸发（MED）海水淡化技术的大规模应用,稳态操作优化虽然能够有效减少MED系统的短期蒸汽消耗速率,但污垢累积导致该系统在长周期运行时蒸汽消耗量升高和装置减产。为此,首先针对带蒸汽压缩机（TVC）的MED系统（MED-TVC）提出可行域的概念,分析表明操作点在可行域中的位置决定了系统的运行效益。随后通过可行域的时变分析发现操作点超出可行域是稳态优化中系统性能逐渐衰减的原因。最后利用可行域的性质,提出了时变约束的全周期操作优化方法。该方法通过调整MED-TVC系统在运行周期内的操作条件,获得全周期最低的蒸汽消耗量,同时利用时变的可行域约束保证优化结果在全周期内均满足淡水产量要求。结果表明,时变约束的全周期操作优化在维持MED-TVC系统的设计淡水产量的同时,全周期蒸汽消耗量相比于设计值减少了19.6%,能够很好地解决MED-TVC系统的操作优化问题。     

On the reduction of desalting energy and its cost in Kuwait

All seawater desalting processes, multi-stage flash (MSF), multi-effect boiling (MEB), mechanical vapor compression (MVC) and seawater reverse osmosis (SWRO) consume significant amounts of energy. The recent increase of fuel oil cost raises the cost of energy consumed for desalting water and the final water cost, and creates more interest in using more energy efficient desalting systems.

The most used desalting systems by distillation (MSF and MEB) are usually combined with power plants in what is called co-generation power desalting plants, CPDP. Fuel is supplied to the CPDP to produce both desalted water D and power W, and the fuel cost is shared between D and W. Exergy analysis and equivalent work are among the methods used to determine the fuel energy charged to each product. When desalting systems, such as SWRO and MVC, are not combined with a power plant, the fuel energy can be directly determined from its electrical power consumption.

In this paper, the fuel energy cost charged to desalting seawater in the presently used CPDP in Kuwait is calculated based on exergy analysis. The MSF, known by its high energy consumption, is the only desalting method used in Kuwait. The MSF units consume 258 kJ/kg thermal energy by steam supplied to the brine heater BH, 16 kJ/kg by steam supplied to steam ejectors, and 4 kWh/m3 mechanical energy for pumping. These MSF units are operated either by:

(1) Steam extracted from extraction/condensing steam turbines EC/ST as in as in Doha West, Azzour, and Sabbiya CPDP. This practice is used in most Gulf area.

(2) Steam supplied directly from boilers as occurred in single purpose desalting plants as Al Shuwaikh plant; or in winter time when no steam turbines are in operation in the CPDP to supply steam to the desalting units.

The CPDP have limited water to power production ratio. While they can cope with the increase of power demand, it cannot satisfy the water demand, which is increasing with higher pace than the power demand.

The case of steam CPDP used in Kuwait is presented in this paper as a reference plant to evaluate the amount of fuel energy consumed to desalt water in MJ/m3, its cost in $/m3. The resulted high fuel cost calls for some modifications in the reference CPDP to lower the energy cost, and to increase its water to power ratio. The modifications include the use of an auxiliary back-pressure steam turbine ABPST supplied with the steam presently extracted to the MSF units. The power output of the ABPST operates MVC or SWRO desalting units; while the ABPST discharged steam operates LT-MEB desalting unit. The desalting fuel energy costs when applying these modifications are also calculated by the exergy analysis and compared with that present situation.

It is also suggested to increase desalted water output by using separate SWRO desalting units operated by the existing power plants of typical η_c = 0.388, or by new combined gas/steam turbines power cycle GT/ST-CC of typical η_c = 0.54 under construction. The SWRO with energy recovery is assumed to consume typical 5.2 kWh/m³ electric energy.     

影响洗油质量的原因及改进措施

对洗油质量差的原因进行了试验和理论分析,认为影响洗油质量的主要原因是馏分塔底过热蒸汽量大和三混馏分(酚油、萘油、洗油)采出口位置不合适,并提出了相应的改进措施,取得了良好的效果。     

Distillation vs. membrane filtration: overview of process evolutions in seawater desalination

The worldwide need for fresh water requires more and more plants for the treatment of non-conventional water sources. During the last decades, seawater has become an important source of fresh water in many arid regions. The traditional desalination processes [reverse osmosis (RO), multi stage flash (MSF), multi effect distillation (MED), electrodialysis (ED)] have evoluated to reliable and established processes; current research focuses on process improvements in view of a lower cost and a more environmentally friendly operation. This paper provides an overview of recent process improvements in seawater desalination using RO, MSF, MED and ED. Important topics that are discussed include the use of alternative energy sources (wind energy, solar energy, nuclear energy) for RO or distillation processes, and the impact of the different desalination process on the environment; the implementation of hybrid processes in seawater desalination; pretreatment of desalination plants by pressure driven membrane processes (microfiltration, ultrafiltration and nanofiltration) compared to chemical pretreatment; new materials to prevent corrosion in distillation processes; and the prevention of fouling in reverse osmosis units. These improvements contribute to the cost effectiveness of the desalination process, and ensure a sustainable production of drinking water on long terms in regions with limited reserves of fresh water.     

Thermal analysis of ME—TVC+MEE desalination systems

Thermal analysis of three different configurations of a multi-effect thermal vapor compression desalting system is presented: conventional ME—TVC,ME—TVC with regenerative feed heaters (ME—TVC,FH) and ME—TVC coupled with a conventional MEE system (ME—TVC+MEE). The analysis is based on the First and Second Law of Thermodynamics. A parametric study was carried out to investigate the impact of motive steam pressure, temperature difference per effect, top brine temperature, feed seawater temperature and motive steam flow rate on the system's performance for each configuration. The exergy analysis showed that irreversibilities in the steam ejector and evaporators are the main sources of exergy destruction in the three configurations. When steam is supplied directly from the boiler to all configurations, results showed that the first effect was responsible for about 50% of the total effect exergy destruction. The study also showed that the decrease in exergy destruction is more pronounced than the decrease in the gain ratio at lower values of motive steam pressure. Lowering the temperature difference across the effects, by increasing the surface area, decreases the specific heat consumption. On the other hand, exergy losses are small at low temperature differences and low top brine temperature. The analysis showed that the third configuration (ME—TVC+MEE) has two main features compared to ME—TVC and ME—TVC, FH. First it has a lower compression ratio, which makes the motive steam capable of compressing larger amounts of the entrained vapor; as a result, the amount of motive steam is reduced. Second, the configuration can be used for large-scale production.     

印尼INDRAMAYU电厂4500t／d低温多效海淡装置介绍

本文对印度尼西亚INDRAMAYU火电厂4500t／d低温多效海水淡化装置的基本参数、技术特点、经济效益和主要制造工序等进行了简要的介绍。该装置是中国首台出口到国外的大型低温多效海水淡化装置，无论装置规模或制造难度上都开创了先例。     

Rapid method for determination of unsulfonated oils

A primary limitation to alkylbenzene sulfonation processes has been the lack of a rapid method to sense the quality of sulfonation. This is especially true for a process using sulfur trioxide where both the level of sulfonating agent and time are critical: too little reagent results in high oils; too much reagent degrades product color; and a delay in the process also degrades color. Although steam distillation of oils from the neutralized sulfonate can be conducted in about one and one-half hours for commercial dodecylbenzene derivatives, far greater time is required for higher molecular weight homologs. Extraction of oils requires about one hour and more operator time than distillation. The use of ethylene glycol as the principal carrier solvent, along with a small amount of water, provides oil values within 10 min distillation time. It is also applicable to longer chain alkylbenzene. sulfonates besides those from dodecylbenzene. Subsequently, extracted oils are high, ca. 90%, in sulfone content. Glycol distilled oils plus subsequently extracted oils (sulfones) are slightly greater than oils obtained exclusively by extraction. It has been realized that some of the more volatile oils are lost during the usual extraction procedure. The glycol oils distillation method has been successfully used in plants for alkylbenzene sulfonic acid quality control.