Energy saving analysis of a hybrid ground-coupled heat pump project

A hybrid ground-coupled heat pump（HGCHP）project in Nanjing,China is chosen to analyze the building energy-consumption properties in terms of different control strategies,building envelope and the terminal air-conditioning system.The HGCHP uses a supplemental heat rejecter to dissipate extra thermal energy to guarantee underground soil heat balance.The software EnergyPlus is employed to simulate the project and design the heat flow of the cooling tower and the borehole heat exchanger（BHE）.Then two feasible control strategies for the cooling tower and the borehole heat exchanger are proposed.The energy-saving potential of the building envelope is analyzed in terms of the surface color of the wall/roof.With the same terminal system,it is found that in the cooling season the heat flow of the insulated building with black wall/roof is 1.2 times more than that with white wall/roof.With the same insulated building and gray wall/roof,it is concluded that the heat pump units for a primary air fan-coil system show an annual energy consumption increase of 44.7 GJ compared with a radiant floor system.

Design of heat exchanger network based on entransy theory

The heat exchanger network(HEN) synthesis problem based on entransy theory is analyzed. According to the characteristics of entransy representation of thermal potential energy, the entransy dissipation represents the irreversibility of the heat transfer process, the temperature difference determines the entransy dissipation, and four HEN design steps based on entransy theory are put forward. The present study shows how it is possible to set energy targets based on entransy and achieve them with a network of heat exchangers by an example of heat exchanger network design for four streams. In order to verify the correctness of the heat exchanger networks design method based on entransy theory, the synthesis of the HEN for the diesel hydrogenation unit is studied. Using the heat exchange networks design method based on entransy theory, the HEN obtained is consistent with energy targets. The entransy transfer efficiency of HEN based on entransy theory is 92.29%, higher than the entransy transfer efficiency of the maximum heat recovery network based on pinch technology.

Optimizing Grids Demand Reduction through Enhanced Heat Transfer in Low-Temperature Waste Heat Driven ORC Systems

With increasing awareness of energy conservation and environmental protection, the Organic Rankine Cycle (ORC) system has gained significant attention. This technology enables the recovery of industrial waste heat, waste incineration heat, and renewable energy sources such as geothermal heat, biomass energy, and solar energy at lower temperatures. However, the low-grade heat source utilized in ORC systems faces a challenge to achieving high power generation efficiency and output power. Therefore, enhancing the power generation capacity of ORC systems is a key research focus in this field. An entranced heat exchanger ORC system with the screw expander driven by the low-temperature heat source is established to investigate the relevant performance. Hot water temperature from 77°C to 132°C is adopted for performance analysis, while the environmental temperature is approximately 25°C. Refrigerant R245fa is selected as the working fluid, and the screw expander is employed for power generation. It is worth noting that the entranced heat exchanger ORC system has significant potential for low-temperature heat recovery. Experimental results indicate that the maximum power output is 12.83 kW, which is obtained at around 105°C hot water inlet temperature. Correspondingly, the average power output remains 11.75 kW, revealing the system’s high stability for power generation. The implementation of a plate heat exchanger for enhanced heat transfer has enabled a 50% reduction in system size compared to traditional shell-tube type ORC systems. Besides, economic calculations demonstrate substantial benefits associated with the ORC system. The calculations indicate an internal benefit of 560,000 RMB/year, accompanied by notable external benefits such as an energy saving and emission reduction potential of up to 784 t CO2 per year. Moreover, the payback period is 2.23 years. It shows a remarkable improvement in terms of performance and excellent economic benefits. As a result, the novel ORC presents a promising alternative for low-grade heat utilization as compared to conventional small-scale ORC systems.

Analysis on Technical Measures on Energy Saving and Consumption Reducing During Stevia Sugar Production

Based on the analysis of actual energy consumptions during stevia sugar production,practical measures were proposed to save energy（ gas,water and powder） consumption and reduce cost through waste heat recycle and utilization,process improvement,equipment operation efficiency,application of newly energysaving equipment,and some project applications were provided as case study for some techniques and methods adopted in the production.

Heat Exchanger Network Retrofit for Optimization of Crude Distillation Unit Using Pinch Analysis

Crude distillation unit(CDU)is regarded as the main energy consumer in the entire refinery process.In this paper,the process simulation software and the energy management software are used to simulate the flowsheet and analyze the energy consumption,respectively.Stream data obtained from an existing CDU are applicable in the pinch analysis.To reduce the amount of cross-pinch heat transfer,three approaches of resequencing,repiping,and adding heat exchangers are adopted.Compared with the existing CDU,the results demonstrate that the inlet temperature of the furnace can be increased by 25.4℃,the amount of hot and cold utilities can be reduced by 15.1%and 19.6%,respectively.The economic evaluation indicates that the operating cost is saved by 8×106$/a,and the payback period is about 9 months.

Heat Exchanger Network Retrofit of Diesel Hydrotreating Unit Using Pinch Analysis

Diesel hydrotreating unit(DHT)is an integral part of the refinery,and its energy-saving optimization is of great significance to the enterprise.In this paper,process simulation software and energy management software are used to simulate the flowsheet and analyze the energy consumption,respectively.Stream data obtained from an existing DHT are applied in the pinch analysis for retrofitting the heat exchanger network(HEN)to achieve maximum energy utilization by using pinch analysis.Since DHT is constrained by pressure,the pressure factor is considered in the process of retrofitting.The results show that the amount of cross-pinch heat transfer is reduced,the inlet temperature of the furnace is increased by 55℃,and the amount of hot and cold utilities can be reduced by 70.25%and 50.16%,respectively.The economic evaluation indicates that the operating cost is saved by 4.39×10^(6)$/a,and the payback period is about 2 months.

Shortcut Method of Design and Energy-Saving Analysis of Sargent Dividing Wall Column

The Sargent dividing wall column can implement four products separation sequences in one column based on Fully Thermally Coupled Distillation Column. The initial design parameters are required for the design optimization or dynamic control of the Sargent dividing wall column, and in order to make the rigorous simulation of the Sargent dividing wall column more conducive to convergence, a ten column model for complex Sargent column is established in this paper,and the shortcut design method of this model is proposed. The internal minimum vapor and liquid flow are obtained by the Underwood equations and the mass balance method and the V-min method. The separation for a 4-component shortcut mixture of pentane, hexane, heptane and octane was considered, while the initial values of design parameters and the ratio of vapor-liquid distribution of each column were calculated by using the shortcut design method of a ten column model. And by comparing the shortcut calculations with rigorous simulation results, the practicality and reliability of shortcut calculations were verified. The reason for energy saving was analyzed based on back-mixing. A virtual heat exchanger is proposed to make the Sargent dividing wall column more energy efficient.

Study of Total Process Energy Integration

The energy utilization consistency method in process integration extracts the key component of process energy utilization, and simplifies the procedure of process analysis and integration. The method allows the conversion of the total process energy integration into a synthesis problem of a pseudo-heat exchanger network. The advantages of using the energy utilization consistency and the pseudo-temperature methods are presented by two examples of integration of large-scale complex processes. The improved genetic algorithm is proved to be an effective tool in the retrofitting procedures.

Implementation of Pre-Heating System in Stenters for Improving Machine Performance and Increasing Efficiency

In textile finishing, stenters always draw considerable attention to newer inventions to boost up production via maximum utilization of energy. Prior to main drying or heat-setting chambers, intermediate heating of cylindrical system especially by steam has a direct blessing to moisture evaporation, processing speed, fabric quality and so on. Based on actual operational data, this study reveals the outcomes of a pre-heating module installed within a stenter. After employing the pre-heating system to knit fabrics of different structures and compositions, 23% - 61% moisture reduction was found and the speed of processing fabrics was increased simultaneously by 17% - 30% without any compromise on fabric quality. Moreover, no less than 8.21% savings in annual electricity consumption were observed.

自动化技术在热处理领域应用研究

随着全球能源危机的加剧和环保要求的提高,制造业特别是热处理行业面临节能减排的压力。自动化技术的引入不仅改革了传统热处理工艺,而且明显提高了能效和安全性。通过优化工艺流程、升级设备、实施实时数据监控等措施,能明显减少能源消耗和有害排放,此外,自动化也带来了操作安全性的提升和生产效率的增加。尽管存在技术和经济的挑战,但通过策略性的投资,企业能有效克服这些障碍,实现长远的环境和经济双重利益。

土壤源热泵地埋管侧水系统优化运行研究

本文基于江苏无锡某典型厂房土壤源热泵空调项目的实测数据,以地源侧系统总能耗最低为目标,构建设备模型对地源水泵运行工况进行优化,并与两种传统控制策略的运行效果进行对比,据此提出进一步的优化建议。结果表明:基于负荷的优化控制策略,其节能效果要明显优于定频控制策略,冬夏季典型测试日平均节能率分别为28.33%和13.27%,相比于5℃温差变频策略节能了3.61%和2.21%。适当增大地埋管的埋管深度或管径,可以进一步提升该优化控制策略的节能效果。传统的定温差控制策略在负荷率大于60%时,可在5℃基础上将温差增加1~5℃以提升节能效果。

基于Aspen Tech的分馏塔用能优化及换热网络夹点分析

炼油工艺过程中,分馏系统的用能优化是换热网络能量优化的必然要求。以荆门石化3.5Mt/a常减压蒸馏装置为例,利用Aspen Plus和Aspen Energy Analyzer软件,对常压塔以及换热网络的用能情况进行分析,提出能量优化利用思路:变工况条件下,首先优化分馏系统操作参数,再以此为条件,优化换热网络结构,才能实现整个网络的能量优化。利用Aspen Plus软件的模型分析功能,确定了常压塔底汽提蒸汽、常压炉出口温度、中段回流以及侧线的最佳操作参数,为换热网络的夹点分析提供基础数据;在分馏塔操作优化基础上,对现有换热网络进行夹点分析,找出最优夹点温差,求得现有换热网络最高理论换热终温(317.7℃),为进一步优化换热网络提出了目标;通过建立现有换热网络的网格图,找出跨夹点换热的换热器(总共有5台),为换热网络的改进提供了方向。

通信基站热交换节能分析与智能控制策略研究

随着5G技术的快速进展,电信运营商正面临日益严峻的能源消耗问题。为了有效应对这一挑战,利用自然冷源降低空调能耗的技术受到了广泛关注。自然通风系统减少了对传统空调的依赖,展现了显著的节能效果。然而,这种方法也存在一定的挑战。例如可能导致粉尘积累和维护难度增加,进而影响设备的正常运行。为克服这些挑战,本文提出采用热交换系统进行机房冷却。这一方案不仅高效利用外部低温空气,还减少了粉尘和其它环境污染的影响。本文通过构建热交换模型,深入分析了热交换系统的可行性,并进一步探讨相关的控制策略,为后续热交换系统的应用提供一定的指引。

涟钢三烧生产技术进步

总结了涟钢三烧烧结机近年来工艺技术、设备改造、技术经济指标等方面取得的重大进步。烧结机利用系数提高到1.51 t/(m^(2)·h),日历作业率达到97.4%,烧结矿转鼓强度提升到78.85%,所对应的2800 m^(3)高炉利用系数由2020年的2.61t/(m^(3)·d)提升到2021年的3.02t/(m^(3)·d)。

密集烤房排湿余热回收系统性能研究

针对密集烤房开式排湿造成的能源浪费问题,设计了一种利用重力热管的排湿余热回收系统。通过烘烤试验研究,得到了排湿气流的状态参数和燃料消耗量。结果表明,密集烤房排湿余热回收系统的平均显热效率为36.61%,平均全热效率为15.97%;与对照烤房相比,每公斤干烟可节约燃料0.22kg,节能率达到9.11%,该系统具有良好的工程应用价值。

基于Flowmaster的换热站运行研究

根据承德热力集团某换热站工程实际,建立Flowmaster模型,对实际工况进行分析,提出了优化调节方案.对不同的工况进行对比分析,发现降低流量可以显著降低水泵功耗,而降低流量导致的供热量减少可以通过提高少量供水温度得到弥补.质量-流量并调的运行方案不仅符合气温变化规律和人体作息习惯,而且可以大幅节约循环泵的耗电量.无论是对提高能源利用率、降低企业成本还是提高供热质量都十分必要.

海洋石油161平台中央空调新型制热节能技术应用研究

为节能降耗、提高平台电站稳定性,采用新型制热节能技术,以平台热介质锅炉系统产生的热油为换热源,替代生活楼中央空调原有的电加热器制热,为平台生活区域供暖。该技术实施后,平台电站负荷有效降低,燃料消耗和平台碳排放量减少。

4.0 Mt/a加氢裂化装置运行过程中问题分析

以4 Mt/a柴油蜡油加氢裂化装置为例,通过分析其运行过程中缠绕管换热器压降低、石脑油分馏塔进料管线振动等热点和难点问题,提出相应的解决方法和措施,同时对大型加氢裂化装置进行了节能优化。结果表明:为实现缠绕管换热温度精准控制,在新装置设计阶段,应优先采用“X”形控制方式,在装置大型化后,根据装置运行特点和场地布置问题,应采取满足管道要求的优化方案。对于设置有石脑油稳定塔和石脑油分馏塔的工艺流程,需重点考虑介质特点,降低管线液击、管线振动所带来的影响。此外,优化新氢压缩机和普通离心泵的运行模式可为大型加氢裂化装置的平稳操作、节能降耗提供一定参考。

现代煤化工气化能耗评价及节能潜力研究

随着全球对可持续发展和碳减排关注的日益增加,煤化工产业正积极寻求技术创新和发展路径的转变,以实现节能减排的目标。煤气化作为煤化工产业链中的关键环节,其气化效率直接影响煤化工产业的能源消耗和环境影响。以煤气化过程中的物料平衡为基础,通过研究碳、氢、氧元素平衡,热量平衡以及反应平衡常数,阐述了各元素在原料、中间产物、最终产物以及副产物之间的转移和分布,并且模拟计算了煤气化产物中一氧化碳(CO)、二氧化碳(CO_(2))、氢气(H_(2))等产率;以此作为能耗评价基础,对气化主要能效指标,包括有效气成分、冷煤气效率、气化效率等进行了评价,分析了煤气化过程中的节能节煤潜力。以水煤浆气化为案例,分析了水煤浆气化过程中物料和能量的流动,并研究了水煤浆气化效率提升的可能性。通过煤制天然气、煤直接液化、煤间接液化和煤制烯烃工艺节能技术路径研究发现,不同煤化工工艺路径只要进行节能降耗优化,均具有节能潜力,同时在煤化工生产企业如果有效进行污染物处理与再利用也能够进一步降低煤耗和能耗、提高资源利用效率。

改良西门子法高纯晶硅精馏工艺的节能改进

改良西门子法的发展因高纯晶硅产能饱和、能耗高而受到限制。为了降低能耗,将工业上常用的精馏节能手段应用于改良西门子法高纯晶硅精馏工艺,采用中间再沸器与热泵精馏两种措施对精馏工艺进行改进,并使用Aspen Plus软件对改进工艺与原工艺进行模拟分析。结果表明,以10万t/a精馏单元为例,该改进工艺可使年运行费用降低759万元,经济效益显著。