工业汽轮机的经济出力分界点

在石化企业蒸汽动力系统中存在大量的减温减压器,将较高压力蒸汽转化为较低压力蒸汽以适用于不同品位热量的需求。此外在夏季企业可能存在低压蒸汽过剩现象。采用背压汽轮机替代减温减压器和凝汽汽轮机回收过剩低压蒸汽能量是节能的有效方法。为了确定采用汽轮机的经济合理的范围,通过经济评价方程,获得了背压汽轮机和凝汽汽轮机的经济出力分界点,并讨论了在不同蒸汽价格或电热比价下该分界点的变化。案例结果表明,该临界值所对应的功率较小,表明在企业多数情况采用汽轮机的节能方案是经济可行的。本文可为在石化企业的节能减排中采用工业汽轮机提供指导和依据。     

甲醇生产系统中汽轮机拖动压缩机工艺的技改效果分析

介绍了甲醇生产系统中2种汽轮机拖动压缩机的工艺流程和设备技术参数;对比了2种汽轮机技术改造方案和工艺技术特点;对汽轮机的改造投资、动力消耗、生产运行状况和经济效益进行了分析。运行效果表明:以蒸汽作为动力进行汽轮机拖动压缩机的改造宜采用背压式汽轮机,背压式汽轮机替代电动机拖动压缩机每年可节约生产费用356.8万元。     

工业汽轮机变工况运行的研究及试验

汽轮机是将热能转化为机械能与电能的主要机械,近年来驱动用工业汽轮机在大型化工装置中得到广泛应用。在汽轮机实际运行当中,工况总是处在变化之中,分析了蒸汽初压变化及新鲜蒸汽温度变化对汽轮机的影响,并进行了蒸汽初压的调整试验,试验结果可为相关工程技术人员提供借鉴。     

Operational optimization of industrial steam systems under uncertainty using data-Driven adaptive robust optimization

This article addresses the operational optimization of industrial steam systems under device efficiency uncertainty using a data-driven adaptive robust optimization approach. A semiempirical model of steam turbine is first developed based on process mechanism and operational data. Uncertain parameters of the proposed steam turbine model are further derived from the historical process data. A robust kernel density estimation method is then used to construct the uncertainty sets for modeling these uncertain parameters. The data-driven uncertainty sets are incorporated into a two-stage adaptive robust mixed-integer linear programming (MILP) framework for operational optimization of steam systems to minimize the total operating cost. Integer variables are introduced to model the on/off decisions of the steam turbines and electrical motors, which are the major energy consumers of the steam system. By applying the affine decision rule, the proposed multilevel optimization model is transformed into its robust counterpart, which is a single-level MILP problem. The proposed framework is applied to the steam system of a real-world ethylene plant to demonstrate its applicability. © 2018 American Institute of Chemical Engineers AIChE J, 65: e16500 2019     

基于鲸鱼优化算法的汽轮机热耗率模型预测

为了准确地建立汽轮机热耗率预测模型,提出了一种基于反向学习自适应的鲸鱼优化算法（AWOA）和快速学习网（FLN）综合建模的方法。首先将改进后的鲸鱼算法与经典改进的粒子群、差分进化算法和基本鲸鱼算法进行比较,结果证明其具有更高的收敛精度和更快的收敛速度;然后采用某热电厂600 MW超临界汽轮机组现场收集的运行数据建立汽轮机热耗率预测模型,并将改进后的鲸鱼算法优化的快速学习网模型的预测结果与基本快速学习网及经典改进的粒子群、差分进化算法和基本鲸鱼算法优化的快速学习网模型预测结果相比较。结果表明,AWOA-FLN预测模型具有更高的预测精度和更强的泛化能力,更能准确地预测汽轮机的热耗率。     

Synthesis of the fluid machinery network in a circulating water system

Energy consumption of the fluid machinery network in a circulating water system takes up a large part of energy consumption in the process industry, so optimization on the network will enhance the economic and environmental performance of the industry. In this paper, a synthesis approach is proposed to obtain the optimal network structure. The effective height curves are used as tools to perform energy analysis, so that the potential placement of water turbines and auxiliary pumps can be determined with energy benefit. Then economic optimization is carried out, by the mathematical model with the total cost as the objective function, to identify the branches for water turbines and auxiliary pumps with economic benefit. In this way, the optimal fluid machinery network structure can be obtained. The results of case study indicate that the proposed synthesis approach to optimize the fluid machinery network will obtain more remarkable benefits on economy, compared to optimizing only the water turbine network or pump network. The results under different flowrates of circulating water reveal that using a water turbine to recover power or adding an auxiliary pump to save energy in branches are only suitable to the flowrate in a certain range.     

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     

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.     

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.     

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。     

基于协同量子粒子算法的透平蒸汽流量软测量

透平蒸汽流量是分析透平运行效率的重要参数,由于现场大量缺乏检测信息,且针对传统测量方法存在可靠性差,非接触式测量成本高、安装困难等问题,提出了一种协同量子粒子算法(CQGAPSO),同时优化神经网络(NN)结构和参数的透平蒸汽流量的软测量建模方法。该方法利用节点间的连接开关,有效消除冗余连接对神经网络逼近能力的影响,引入量子概率幅编码和协同机制来提高神经网络的学习效率、逼近精度和泛化能力。透平蒸汽流量软测量的仿真结果表明:相比全连接神经网络和其他模型,所述方法具有更好的预测精度和鲁棒性。     

Optimal design of hybrid RO/MSF desalination plants Part III: Sensitivity analysis

This is the last paper in a series of three parts entitled “Optimal design of hybrid RO/MSF desalination plants”. This research is concerned with exploring the feasibility of hybridization of multi-stage flash (MSF) and reverse osmosis (RO) technologies in order to improve the performance characteristics and process economics ofthe conventional MSF process. The research project involved an optimization study where the water cost perunit product is minimized subject to a number of constraints. In the first part, the design and cost models were presented, the optimization problem formulated and solutions for a number of cases were outlined. In the second part, results were presented and discussed. In this paper we discuss the sensitivity of water cost from the alternative plant designs to variations in some cost elements and operating conditions. In general, it is concluded that, for the same desalting capacity, hybrid RO/MSF plants can produce desalted water at a lower cost than brine recycle MSF plants, while hybrid plants are characterized, by lower specific capital costs and higher water recovery fractions. Reduction in steam cost allows MSF to compete more with hybrid RO/MSF plants. This result explains the advantage of coupling MSF plants and steam power plants where the exhaust steam from the back pressure turbine represents a relatively cheaper source of heat for the MSF process. Results showed that the RO technology exceeds all other designs over the whole range of energy, chemicals and membrane costs studied here. However, water cost of the RO process was the most sensitive to variations in membrane and electricity costs compared to other hybrid configurations.     

合成氨装置蒸汽轮机结垢原因分析

通过对合成氨装置不同工艺部位蒸汽品质和水质的详细分析，初步确定蒸汽透平结垢的主要原因，并采取措施，通过控制透平用蒸汽、自产蒸汽、锅炉给水等各项指标，使四大机组运行情况较往年同比状况良好，达到了蒸汽管网稳定运行的目标。     

Coupling of standard condensing nuclear power stations to horizontal aluminum tubes multieffect distillation plants

No large nuclear back-pressure turbines are available to day. Standard condensing nuclear turbines could operate continuously with a back-pressure of up to 7″ Hg, exhausting huge amounts of steam at 56°C - 640°c with a loss of electricity production of only 6%–10%. p]The horizontal aluminium tube multieffect distillation process developed by “Israel Desalination Engineering Ltd.” is very suitable for the use of such low-grade heat. A special flash-chamber loop constitutes a positive barrier against any possible contamination being carried over by the steam exhausted from the turbine to the desalination plant. The operation is designed to be flexible so that the power plant can be operated either in conjunction with the desalination plant, or as a single purpose plant. Flow sheets, heat and mass balances have been prepared for eight different combinations of plants. Only standard equipment is being used in the power plant.

The desalination plant consists of 6 to 12 parallel double lines, each of them similar to a large prototype now being designed.

Water production varies between 50 and 123 MGD and water cost between 90 and 137 ¢/1000 gallons.

Costs are based on actual bids.     

炼厂低压蒸汽汽轮机应用比较

在新建和改扩建的炼厂项目中,经常采用低压蒸汽进背压汽轮机做功来拖动转动设备,并背出低低压蒸汽供工艺装置使用.汽轮机拖动转动设备可采用两种方案,其一是拖动多台低功率泵、风机等小型设备;其二是拖动一台大功率背压发电机,利用电能拖动小型设备运转.针对汽轮机用作发电和工业拖动两种用途,对比分析炼厂在蒸汽不足和过剩的情况下汽轮机的运行经济性.通过工程实例比较,在同等进汽情况下,汽轮机发电的经济性往往要好于工业拖动汽轮机.     

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.     

An energy management computer program for process plants

An energy management program has been developed which can be customized for any typical plant which uses optional steam turbines and electric motors. The plant energy cost can be minimized by using the optimum combination of optional equipment. A huge sum of energy cost can be saved even during the period with lower energy cost as present.     

Simultaneous optimization of energy and materials based on heat exchanger network simulation for diesel hydrotreating units

A multi-period nonlinear programming (NLP) formulation is presented in this paper. This is intended to optimize energy and materials simultaneously for diesel hydrotreating units in order to minimize the total costs which include product income, material cost, energy cost, and other fixed operating costs. The heat exchanger network (HEN) is integrated into the model to address the energy consumption changes with the stream flow and temperature of different production modes. Some process models are regressed from production data or are supplied by refinery engineers, similar to the models for steam turbines and compressors, and distillation towers. An iterative algorithm is developed to solve the complex mathematical model based on HEN simulation. An industrial diesel hydrotreating unit is provided by the Chinese Refinery Complex and is used to demonstrate the performance of the formulated model and algorithm. It is found that the optimized results from the simultaneous consideration of the energy and materials are more profitable than those obtained from other methods that individually optimized the energy or materials.     

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.     

Modeling and simulation of motor/turbine processes in utility plant

To achieve safe operation and to improve economics it is imperative to monitor and analyze demand and supply of utilities and to meet utility needs in time. The main objective of motor/turbine processes is to manipulate optimal balances on steam and electricity in utility plants. The optimal operation of motor/turbine processes is by far the most important to improve economics in the utility plant. In order to analyze motor/turbine processes, steady state models for steam generation equipment and steam distribution devices as well as turbine generators are developed and analyzed in this work. In addition, heuristics concerning various operational situations are incorporated in the models. The motor/turbine optimal operation system is based on utility models and operational knowledgebase, and provides optimal operating conditions when the amount of steam demand from various steam headers is changed frequently. The optimal operation system also produces optimal selection of driving devices for utility pumps to reduce operating cost.