Technical and economic analysis for the integration of small reverse osmosis desalination plants into MAST gas turbine cycles for power generation

A technical and economic analysis concerning the integration of small reverse osmosis (RO) desalination plants into mixed air steam turbine (MAST) technologies for power generation was carried out. The simulation tool used is the computer aid reverse osmosis calculations optimization algorithm. This user-friendly software takes into account the capital cost, fuel cost and operation and maintenance requirements of each candidate RO desalination plan scheme and calculates the least-cost configuration. The results indicate that the integration of a RO desalination plant into MAST gas turbines has a minor effect on the final operating cost of the power plant.     

Analysis of cogeneration in the present energy framework

In this paper, a general vision of cogeneration penetration in the European Union is shown; after this, a case study is included, evaluating as a function of two factors (electricity and emission allowance prices) the suitability of installing, for an industry with a determined thermal demand, two different options. The first one is a gas turbine cogeneration plant generating steam through a heat recovery steam generator (HRSG). The second one consists of installing a natural gas boiler for steam production covering the electricity demand from the grid. The CO₂ emissions from both options are compared regarding different kinds of generation mixes from the electricity grid in the case of using the industrial boiler; taking into account the advantages of using biomass in relation to emissions, a last comparison has been carried out considering a biomass boiler instead of the natural gas boiler.     

装置蒸汽动力系统与热电厂运行同步优化

石化企业装置蒸汽动力系统通常独立设计和操作,忽视了与热电厂蒸汽动力系统的联系。热电厂蒸汽动力系统通常在固定的蒸汽和电力需求下进行优化,忽视了与装置蒸汽动力系统的联系。为实现石化企业蒸汽动力系统的全局优化,本文提出了用于装置蒸汽动力系统与热电厂运行同步优化的方法。首先使用热电厂透平和锅炉的设计及运行数据回归得到设备模型系数,依照现有结构建立热电厂蒸汽动力系统约束。然后以装置蒸汽动力系统设计和操作灵活性为区分,将装置分为三类：第一类装置蒸汽和电力需求无法调节;第二类装置可以通过减温减压调节蒸汽需求;第三类装置既可以通过减温减压调节蒸汽需求,也可以通过驱动选择调节热电需求。装置透平模型参数采用文献值,通过采集各类装置蒸汽和电力需求等数据建立装置蒸汽动力系统约束,最后通过热电厂与装置蒸汽和电力的连接关系建立耦合模型。耦合模型以年度费用为目标函数,其中包括热电厂运行费用以及装置透平和电机的年度投资费用,通过优化求解得到热电厂设备负荷分配方案以及装置蒸汽动力系统设计方案。通过算例论证了同步优化方法的可行性,与独立优化相比,同步优化降低年度费用451万美元。     

Analysis of water desalination and power generation expansion plans for the Emirate of Abu Dhabi — a preliminary study

This paper contains a comparative economic study of a number of different expansion schedules for power and desalination plants required to meet a forecasted demand in electricity and water for the Emirate of Abu Dhabi. For power generation, steam turbine and gas turbine plants were considered and for desalination both multistage flash distillation and reverse osmosis processes were investigated. Nine combinations of power and desalination plants were selected and a present worth economic analysis was conducted. Capital and operating cost figures used are those typical of the local conditions at Abu Dhabi. Based on the assumptions used in this study the plant combination using steam turbine power plant connected to a reverse osmosis unit seems to represent the most economic alternative.     

IGCC常规岛系统优化设计研究

建立200 MW级整体煤气化联合循环（IGCC）发电系统模型,以整体性为原则,基于各设备单元的物质平衡、能量平衡以及化学反应平衡对IGCC系统进行计算,探讨不同汽水循环形式、不同余热锅炉与废热锅炉汽水配置方式对IGCC发电系统性能的影响。结果表明：在本研究系统中,选择三压再热汽水循环形式,可进一步回收燃气轮机的排气余热,同时提高了汽轮机的初参数,有利于提高系统性能;余热锅炉高压省煤器的汽水配置遵循＂温度对口、能量梯级利用＂的原则,以获得较高的整体性能。研究结果为同级别IGCC系统中常规岛的优化设计提供参考。     

Development and optimization of ME-TVC desalination system

Significant and rapid developments have taken place recently in the multi-effect thermal vapor compression (ME-TVC) desalination system of SIDEM Company, particularly in enlarging the unit capacity. The new trend of combining ME-TVC with conventional multi-effect has allowed this unit capacity to increase from two to eight million imperial gallons per day (MIGD) in the last decade. This considerable increase in capacity, poses a real competition to the multi stage flash system (MSF) as a large-scale production plant with lower operation temperatures.A steady state mathematical model of the ME-TVC desalination system is developed in this paper using Engineering Equations Solver (EES) to evaluate the model system performance. The model validity is examined against three commercial ME-TVC units which showed good results. The main improvements in the performance during the past ten years are also outlined and discussed. Another purpose of this paper is to determine the optimum operating and design conditions of the ME-TVC desalination system through mathematical modeling optimization. A MATLAB algorithm solution is developed and used to solve model equations, where a different number of effects were tested to maximize the gain ratio using (1) Smart Exhaustive Search Method and (2) Sequential Quadratic Programming. Results showed that the maximum gain ratio varied between 8.5 and 18.5 for 4 and 12 effects with the optimal top brine temperature ranging between 55.8 and 67.5 °C and a reasonable specific heat transfer area. The optimal ranges of compression and entrainment ratios are between 1.81 to 3.68 and 0.73 to 1.65 respectively. The optimal results of 4-effect TVC unit are also compared with three commercial 4-effect units having almost the same input, which showed that further improvement in the distillate output production, compression and entrainment ratio can be achieved by combining the ME-TVC system with conventional multi-effect unit.     

Optimization of integrated cogeneration power plant and desalination plant systems for a range of power and water supply requirements

Comparative economic analysis is presented which shows necessity of integrated power and desalination plants optimization rather than separate optimization of power generating and desalination units. This paper introduces:- Calculational procedure and resulting curves for cogeneration plant selection for a range of power and steam demands.- Conceptual procedure for integrated power plant and desalination plant system optimization.- Results of comparative economic analysis of integrated power/ desalination plant optimization as compared with separate power plant and desalination plant optimization.     

Gas Turbine Direct Integration in the Context of Pinch Technology

Gas‐turbine‐based cogeneration systems have been widely used in different applications in recent years. Although the most common method of using gas turbine exhaust energy is through the generation of steam in a heat recovery boiler, there are some applications where the exhaust energy has been directly used for drying or process fluid heating. In this work, direct integration of a gas turbine with a process was fully investigated in the context of pinch technology. This investigation includes simple gas turbine and gas turbines equipped with recuperator and afterburner. It was found that the best thermodynamic efficiency in a direct gas turbine system is achieved when two conditions are met: first, turbine inlet temperature is maximized, second, optimum pressure ratio is that which yields the maximum specific network. Two total cost optimization methods were also introduced. The first method is based on the assumption that power produced equates to power demand. In the second approach the power export opportunity was also considered. Finally, illustrative examples have been presented to show how approaches can be applied in practice.     

Synthesis of mechanical driver and power generation configurations,Part 1: Optimization framework

This article presents a novel, systematic, and robust procedure for driver and power plant selection based on mathematical programming. The discrete nature of gas turbines is considered as gas turbine drivers and gas turbine‐based power plants are selected from a group of candidates. Plant availability with considering parallel compression has also been included, which allows a more comprehensive exploitation of the trade‐offs between capital costs, operating costs, and availability. When neglecting process heating and any steam equipment, the formulation can be applied to heavily power dominated processes, such as LNG. However, a more comprehensive formulation, allowing waste heat recovery and the integration with a multilevel steam system, is also proposed to produce more thermally efficient systems. This approach proved to be flexible and robust and is the first in producing solutions ranging from no‐steam to all‐steam systems, including all‐gas turbine, all‐motor and hybrid gas turbine/motor/steam systems. © 2010 American Institute of Chemical Engineers AIChE J, 2010     

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.     

注蒸汽燃机-热蒸馏海水淡化复合系统的环境负荷及其分摊

以注蒸汽燃机-热蒸馏海水淡化复合系统为例,基于火用经济学理论,建立了系统中电、水环境负荷的分摊模型,初步分析了系统的生命周期污染物排放,计算了系统中各火用流以及系统产品的环境负荷向量,得到了电、水的环境负荷分摊比。本文的研究虽然基于注蒸汽燃机-热蒸馏海水淡化系统而进行,但所探讨的方法同样适用于以干式燃机或其他湿式燃机为基础的电水联产系统。     

Optimization analysis of dual-purpose systems

This paper aims to analyze dual-purpose systems focusing the total cost optimization; a superstructure is proposed to present cogeneration systems and desalination technologies alternatives for the synthesis process. The superstructure consists of excluding components, gas turbines or conventional steam generators with excluding alternatives of supplying fuel for each combustion system. Also, backpressure or condensing/extraction steam turbine for supplying process steam could be selected. Finally one desalination unit chosen between electrically-driven or steam-driven reverse osmosis, multi-effect and multistage flash should be included. The analysis herein performed is based on energy and mass conservation equations, as well as the technological limiting equation of equipment. The results for ten different commercial gas turbines revealed that electrically-driven reverse osmosis was always chosen together with both natural gas and gasified biomass gas turbines.     

Cost optimization of a combined power and water desalination plant with exergetic,environment and reliability consideration

The present study deals with the multi-objective optimization for designing a combined gas turbine and multi stage flash desalination plant. In optimization approach, the exergetic, economic and environmental aspects have been considered, simultaneously. In order to achieve the optimal design, Multi-objective genetic algorithm (MOGA) is applied as a suitable optimization technique. The thermoenvironomic objective function is obtained by integrating the environmental impacts and thermoeconomic objective. By applying the optimization approach, this objective function is minimized, whereas system exergy efficiency is maximized. Moreover, equipment reliability using the state-space and the continuous Markov method is incorporated in optimization results to improve the products' cost values. The optimization results show that the cost of products and environmental cost impact are reduced by 13.4% and 53.4%, respectively, whereas a 14.8% increase happens in total exergy efficiency. Therefore, improvement in all objectives has been achieved using the optimization process, although the power and water productions have not changed much. Additionally, the sensitivity analysis shows the relationship between the fuel cost, pollution damage cost and the objective functions.     

A Thermodynamic Approach to the Integrated Design of a Combined Cycle Cogeneration Plant

A thermodynamically oriented approach for the integrated design of a combined cycle cogeneration plant (CCCP) meeting a given sites requirements for process steam and power has been developed. It has been shown that the most efficient plant, for a targeted stack temperature, is achieved when the gas turbine cycle is designed for maximum specific net work and the steam turbine cycle is designed for maximum cycle efficiency. Based on this approach a computer program for rigorous analysis has also been developed.     

基于液态空气储能技术的新型整体煤气化联合循环系统分析

液态空气储能技术是一种环境适应性好、容量大的电能存储技术,将液态空气储能技术与整体煤气化联合循环发电系统(IGCC)相结合,利用液空储能技术获取燃气轮机发电所需的高压空气,提高燃气轮机的出功,同时提高IGCC发电系统调峰、调频的能力,提高电能质量。本文从热力学角度出发,对该新型整体煤气化联合循环发电系统进行分析计算,建立系统物质和能量平衡,计算了系统的主要工艺参数。结果表明,净功率为150MW的液态空气-整体煤气化联合循环发电系统,燃气轮机净功率为95.9MW,汽轮机功率为53.9MW,系统热效率为52.8%;相同参数下未应用液态空气储能技术的整体煤气化联合循环发电机组功率为151.4MW,而传统简单循环燃气发电机组热效率仅为35.8%。     

CSP电站汽轮机选型分析

与传统火电用汽轮机不同,光热发电用汽轮机具有机组容量相对较小、受环境影响因素多、每天频繁启停、运行负荷低等特点。尽管光热电站中汽轮机投资的占比较小,但汽轮机效率对整个电站经济性至关重要。本文阐述了光热电站主机特点和供应商情况,分析了汽轮机进汽、排汽参数的选取要点,以及工况设定原则和注意事项,为开展光热电站主机选型提供指导和建议。     

Optimal coupling of waste and concentrated solar for the constant production of electricity over a year

In this article, a biogas-based Brayton cycle is integrated with a concentrated solar power facility. The gas turbine hot flue gas and the molten salts are used to generate steam for the regenerative Rankine cycle. The process model is solved as a nonlinear optimization problem within a multiperiod scheme to decide on the contribution of the energy resources and the operating conditions of the facility to meet a certain demand of power over a year mitigating the absence of solar availability. The steam turbine is responsible for power production while the gas turbine works mainly as a combustion chamber. In the South of Spain, an excess of biogas is available during summer yielding a production cost of electricity of 0.17 €/kWh with an investment of 380 M€ for a production facility of 25 MW. This plant is not yet economic.     

Analysis of water and power costs by various methods,based on Jeddah IV

The Jeddah IV Power and Desalination Plant is the biggest, dual-purpose plant in the world. Moreover, it is perhaps the first plant of this kind for which authentic cost and operational data are available. As such, it provides a reliable means of assessing the present status of desalination technology and its influence on the cost of power and water.The well-known theoretical methods of cost allocation are used in deriving the product cost from the Jeddah IV plant. The influence of local factors and contractual constraints is discussed. Extrapolations are made to determine the projected cost of water on similar plants but with different performance ratios. Recommendations are made on cost optimization and the most favourable combination for dual-purpose power/desalination plants based on steam turbines and MSF process.     

Conceptual design of a novel hybrid fuel cell/desalination system

A novel concept for integrating fuel cells with desalination systems is proposed and investigated in this work. Two unique case studies are discussed — the first involving a hybrid system with a reverse osmosis (RO) unit and the second — integrating with a thermal desalination process such as multi-stage flash (MSF). The underlying motivation for this system integration is that the exhaust gas from a hybrid power plant (fuel cell/turbine system) contains considerable amount of thermal energy, which may be utilized for desalination units. This exhaust heat can be suitably used for preheating the feed in desalination processes such as reverse osmosis which not only increases the potable water production, but also decreases the relative energy consumption by approximately 8% when there is an increase of just 8°C rise in temperature. Additionally, an attractive hybrid system application which combines power generation at 70%+ system efficiency with efficient waste heat utilization is thermal desalination. In this work, it is shown that the system efficiency can be raised appreciably when a high-temperature fuel cell co-generates DC power in-situ with waste heat suitable for MSF. Results indicate that such hybrid system could show a 5.6% increase in global efficiency. Such combined hybrid systems have overall system efficiencies (second-law base) exceeding those of either fuel-cell power plants or traditional desalination plants.     

改进PSO算法在蒸汽动力系统多周期运行优化中的应用

为了满足石化企业工艺过程对蒸汽和电力不断变化的要求,实现企业降低成本、节能降耗的目的,必须保证蒸汽动力系统在最优的状态下运行。针对这一问题在以往研究的基础上提出了包括设备维护和启停费用的改进的混合整数线性规划模型,利用改进的PSO算法对其求解,并通过实例证明了利用该模型、使用改进的PSO算法能很快得到最优的方案,并节省了大量的运行成本。