空分流程中几个基本热力过程的Yong分析

简介了Yong的概念及计算方法，对空分流程中几个基本热力过程进行 Yong分析，从更深层次揭示了这些基本热力过程的实质，从而为优化这些热力过程、进一步降低不可逆损失指明方向，把这些基本的分析方法用于整体空分流程，将会对流程的改进和优化有较好的指导作用。     

二○○二年度《深冷技术》目次索引

※专题综述※空分流程中几个基本热力过程的火用分析毛绍融 ,钱宇峰　 1　 1………………………………………碳氢化合物对泵压流程空分设备安全性的影响及措施李大仁　 2　 1…………………………………………………低温法小型空分设备 :技术进步、与液体输送的竞争和对策江楚标　 3　 1…………………………………………………宝钢 72 0 0 0ｍ3/ｈ空分设备和膜式冷凝蒸发器杨涌源　 4　 1………钢铁企业用空分装置的调峰、氧气终压及适用流程的探讨江楚标　 5　 1…………………………………………………钢铁企业氧气放散与空分设备的负荷…     

基于分析的空调系统运行控制的多目标优化

针对空调系统运行效率低下,且运行过程中子系统之间相互影响、相互制约的问题,本文基于分析方法提出一种空调系统多目标运行优化方法,以提高空调系统整体的运行效率。以某机场航站楼空调系统为研究对象,采用分析方法建立了空调系统的生产结构图,并根据生产结构将空调系统划分为3个子系统。在建立子系统分析模型的基础上,以3个子系统的最小损为优化目标,采用多目标粒子群优化算法(MOPSO)对空调系统的运行参数进行优化。针对某一典型日的运行工况对空调系统进行多目标优化,结果表明:相对于空调系统的原始控制方式,采用多目标运行优化方法可以有效减小空调各个子系统以及整个系统的损,使空调系统的运行效率明显提高,达到了节能的目的。     

大型化工型内压缩流程空分设备新工艺的研制与发展

针对煤化工装置对气体产品的新要求,从流程选择、优化、节能和安全供气等方面对大型化工型内压缩流程空分设备进行了研究;指出:合理选择单套空分设备规模,发挥多套空分设备联合供气的最大优势;合理、优化改造全精馏无氢制氩系统;设置安全、可靠的液体汽化后备系统;用液体膨胀机代替高压节流阀,是大型化工型内压缩流程空分设备的新特点和发展方向。     

大型空分装置预冷系统的研究

本文从大型空分预冷系统的流程组织与分析、单体设备的设计与优化等方面,总结了开封空分集团设计研究院对空分装置预冷系统的研究。     

自动变负荷及优化控制在空分设备中的应用

综述国内外大型空分设备的自动变负荷及优化控制技术的发展状况,分析自动变负荷及优化控制技术的难点,结合国内首套国产空分装置的自动变负荷及优化控制应用情况,对空分设备自动变负荷及优化控制的系统结构和操作流程等进行了较全面的阐述。     

空分装置制冷量及冷损构成的讨论

通过做出内外压缩空分流程简化流程图和T-S热力示意图,列出基本的物料和产冷量与耗冷量之间的能量平衡方程,从原理上揭示出内外压缩空分流程制冷量和冷损的构成差异.分别举例阐述了内外压缩空分流程的各项制冷量与各项冷量损失之间的平衡关系.特别指出了内压缩空分流程高压产品气除热端复热不足冷损外,还有额外带走的压力冷损,这是与外压缩空分流程的不同之处.同时,对内外压缩空分流程的制冷量及冷损构成做了定量分析.     

KDON-33600/27500型空分设备的设计缺陷及整改措施

介绍KDON-33600/27500型双泵内压缩流程空分设备在高压液空节流阀、液氧泵密封气和加温气流程以及膨胀机喷嘴加热器控制程序方面存在的设计缺陷,分析了这些缺陷对空分设备安全、稳定运行的影响以及采取的整改措施。     

超低压空分设备流程的可行性分析

对空分流程的发展历史进行了简述,超低压空分流程作为新一代空分流程,对其进行了研究和探讨。提出了具体流程方案并进行了阐述。     

富氧燃烧用空分工艺流程研究

根据富氧燃烧对氧浓度的需求(氧浓度≥95%),进行空分流程优化,研究低能耗低成本的空分工艺。本文介绍三塔精馏空分设备的工艺流程特点。     

Thermodynamic optimization of reverse Brayton cycles of different configurations for cryogenic applications

The thermodynamic optimization of differing Reverse Brayton Refrigeration (RBR) cycle configurations is presented in this study. These cycle configurations include: Conventional 1-stage compression cycle; Conventional 2-stage compression cycle; 1-stage compression Modified cycle with intermediate cooling of the recuperator using an auxiliary cooler; and an Integrated 2-stage expansion RBR cycle. For high pressure ratio applications, multi-stage compressors with intercooling are considered. Analytical solutions for the conventional cycles are developed including thermal and fluid flow irreversibilities of the recuperators and all heat exchangers in addition to the compression and expansion processes. Exergy analysis is performed and the exergy destruction of different components of the RBR cycles for different configurations is presented and the effects of important system parameters on performance are investigated. Thermodynamic optimization of the cycles with intermediate cooling of the recuperator is included. Effects of the 2nd law/exergy efficiency of the auxiliary cooler on the total system efficiencies are presented.     

空分设备有效能损失分析及节能改造

空分设备有效能损失主要存在流体的压缩与膨胀、热交换、精馏及节流减压等。通过节能改造和优化操作,提高了有效能的利用率,从而达到降低空分设备能耗的目的。     

Thermodynamic performance assessment of a novel air cooling cycle: Maisotsenko cycle

This study presents energy and exergy analyses and sustainability assessment of the novel evaporative air cooling system based on Maisotsenko cycle which allows the product fluid to be cooled in to a dew point temperature of the incoming air. In the energy analysis, Maisotsenko cycle’s wet-bulb and dew point effectiveness, COP and primary energy ratio rates are calculated. Exergy analysis of the system is then carried out for six reference temperatures ranging from 0 °C to 23.88 °C as the incoming air (surrounding) temperature. The specific flow exergy, exergy input, exergy output, exergy destruction, exergy loss, exergy efficiency, exergetic COP, primary exergy ratio and entropy generation rates are determined for various cases. Furthermore, sustainability assessment is obtained using sustainability index method. As a result, maximum exergy efficiency is found to be 19.14% for a reference temperature of 23.88 °C where the optimum operation takes place.     

A model for exergy analysis and thermodynamic bounds of Stirling refrigerators

A thermodynamic model based on exergy flow through a Stirling Refrigerator is developed. Important irreversibilities of the refrigerator due to external heat transfer with the reservoirs, heat leak, flow and heat transfer in regenerator are included in the model. Expansion and compression efficiencies are introduced in the model to account for the losses in these processes. The effect of a control phase shift between the mass flow rate and pressure across regenerator on the performance of the refrigerator is presented. Analytical solutions representing important quantities in the design of Stirling refrigerators such as the load curve, cooling power and efficiency in terms of basic system input parameters are developed. Thermodynamic bounds for the performance of Stirling refrigerators are obtained. Results indicating a compromise between cooling power and efficiency that are dependent on the constraint of the system are presented and discussed.     

Multi-objective optimization of a cooling tower assisted vapor compression refrigeration system

A cooling tower assisted vapor compression refrigeration machine has been considered for optimization with multiple criteria. Two objective functions including the total exergy destruction of the system (as a thermodynamic criterion) and the total product cost of the system (as an economic criterion), have been considered simultaneously. A thermodynamic model based on energy and exergy analyses and an economic model according to the Total Revenue Requirement (TRR) method have been developed. Three optimized systems including a single-objective thermodynamic optimized, a single-objective economic optimized and a multi-objective optimized are obtained. In the case of multi-objective optimization, an example of decision-making process for selection of the final solution from the Pareto frontier has been presented. The exergetic and economic results obtained for three optimized systems have been compared and discussed. The results have shown that the multi-objective design more acceptably satisfies generalized engineering criteria than other two single-objective optimized designs.     

A thermodynamic model based on exergy flow for analysis and optimization of pulse tube refrigerators

A thermodynamic model based on exergy flow through pulse tube refrigerators (PTRs) is developed. An exergetic efficiency parameter representing the losses in the pulse tube itself is proposed. The effects of control parameters representing a general phase shifter and their effect on the system performance are discussed. Analytical solutions representing important parameters in the design of PTRs such as the load curve, cooling power and efficiency in terms of basic system input parameters are developed. It is shown that the analytical model is powerful and convenient for optimization of PTRs and in quantifying its operational bound and important losses. Results indicating a compromise between cooling power and efficiency in PTRs under certain conditions are presented and discussed.     

Thermodynamic analysis and optimization of a novel two-stage transcritical N2O cycle

Thermodynamic (energy and exergy) analyses and optimization studies of two-stage transcritical N₂O and CO₂ cycles, incorporating compressor intercooling, are presented based on cycle simulation employing simultaneous optimization of intercooler pressure and gas cooler pressure. Further, performance comparisons with the basic single-stage cycles are also presented. The N₂O cycle exhibits higher cooling COP, lower optimum gas cooler pressure and discharge temperature and higher second law efficiency as compared to an equivalent CO₂ cycle. However, two-stage compression with intercooling yields lesser COP improvement for N₂O compared to CO₂. Based on the cycle simulations, correlations of optimum gas cooler pressure and inter-stage pressure in terms of gas cooler exit temperature and evaporator temperature are obtained. This is expected to be of help as a guideline in optimal design and operation of such systems.     

Discussion on refrigeration cycle for regenerative cryocoolers

Based on review and analysis of thermodynamic efficiency ε of the Carnot cycle and the cycle with two isothermal and two polytropic processes, another thermodynamic cycle with two isentropic and two polytropic processes, which can achieve the Carnot value of thermodynamic efficiency, is testified theoretically. Thermodynamic efficiency expressions of a number of ideal regenerative refrigeration cycles are derived, including the ideal pulse tube refrigeration cycle. A classified branch chart and a plot of ideal thermodynamic efficiency of regenerative refrigeration cycles are given for the purpose of comparison.     

半冷半压式液化石油气船再液化装置研究

再液化装置是半冷半压式液化石油气船的关键设备,在保障液化石油气船运营的安全性和经济怀方面发挥着重要作用。首先对大型半冷半压式液化石油气船再液化装置适用的制冷循环类型进行了分析,然后在液化热力参数计算的基础上对低温液化流程进行了热力计算与优化,最后对再液化装置进行了有效能分析,提出了减少再液化装置有效能损失的措施。     

Conceptual design and exergy analysis of an integrated structure of natural gas liquefaction and production of liquid fuels from natural gas using Fischer-Tropsch synthesis

In this paper, utilizing absorption refrigeration system as an alternative to compression refrigeration system of MFC refrigeration cycle in an integrated superstructure with the main aim of reduction in required energy is investigated. High-energy consumption in such units is reduced because of the removal of a stage of the compression system, while the possibility of using waste energy through employing of absorption refrigeration system can be provided. A superstructure including cogeneration of heating, cooling and power for LNG production and liquid fuels using Fischer-Tropsch synthesis are investigated. Exergy analysis shows that the greatest amount of exergy destruction of equipment is related to the compressors by 28.99% and the lowest exergy destruction is related to the gas turbine by 0.17%. Integrated structure has overall thermal efficiency of 90% and specific power of 0.1988 kW h/(kg LNG)⁻¹.