Utilization and recycling of low-temperature waste heat of stainless steel continuous annealing furnace

Stainless steel continuous annealing furnace is mainly used for heat treatment of hot-rolled strip steel.The combustion air will be enabled to heat to 520℃by waste heat recovery system,but the discharge temperature is still up to about 300℃.Owing to with development of global emphasis on energy conservation energy saving and discharge reduction,it's significant to lower the discharge temperature to below 200℃, for the sake of achieving rational use of waste heat resource.Through the analysis of the existing heat recovery system by this study,it is proved that mixing low temperature with flue gas in high temperature standard will increase the capacity of the flue gas and deteriorate the quality of remaining heat resource.In stead of that,increasing the combustion air temperature to 600℃on the basis of stability temperature for the prerequisite of recuperator design,and giving priority to reducing fuel consumption are the better way.The recovery and recycle of low temperature gas are also be introduced.It is demonstrated by the way of setting a secondary recuperator at the exit of the primary recuperator,and using low temperature flue gas to heat the air used for drying the strip steel,the exhuast temperature of flue gas can be reduced to lower than 200℃.At the same time,the steam required for heating air is saved,the energy reserve as high as 2 300 t of standard coal per year.

Aqueous ammonia solution cooling absorption refrigeration driven by fishing boat diesel exhaust heat

A solution cooling absorption（SCA）approach is proposed to modify the aqueous ammonia absorption refrigerat-ion cycle using the strong solution from the absorber to cool the forepart of the absorption in the cycle for reclaiming some portion of absorption heat.As a consequence of raised temperature at the inlet,the strong solution partially boils at the outlet of the solution heat exchanger,and diminishes the thermal heat consumption of the heat source.The calculation results show that the coefficient of performance（COP）of this modified cycle is about 28.3% higher than that of the traditional cycle under typical conditions;while the required heat transfer area of the total heat exchangers of the cycle is somewhat less than that of the traditional one.The capacity of refrigeration with the new absorption cycle is more than doubled in contrast to the adsorption scheme with an identical configuration.It is sufficient to supply a fishing boat the chilling capacity for preservation of fishing products with the modified cycle chiller driven by its diesel engine exhaust.

A review of low-temperature heat recovery technologies for industry processes

The amount of low-temperature heat generated in industrial processes is high,but recycling is limited due to low grade and low recycling efficiency,which is one of the reasons for low energy efficiency.It implies that there is a great potential for low-temperature heat recovery and utilization.This article provided a detailed review of recent advances in the development of low-temperature thermal upgrades,power generation,refrigeration,and thermal energy storage.The detailed description will be given from the aspects of system structure improvement,work medium improvement,and thermodynamic and economic performance evaluation.It also pointed out the development bottlenecks and future development trends of various technologies.The low-temperature heat combined utilization technology can recover waste heat in an all-round and effective manner,and has great development prospects.

Electricity Generation from Low Temperature Waste Heat with Application to Hydrogen Production from Water

This paper presents an extensive study of the heat pump cycle and associated working fluids to generate electricity from low temperature industrial waste heat. An Aspen Plus simulation has been developed to evaluate the effect of various working fluids on the net heat pump efficiency over a wide range of turbine inlet temperatures between 50℃ and 250℃. One hundred eight （108） refi＇igerants were investigated from the environmental classifications of Hydrochlorofluorocarbons （HCFC）, Hydrofluorocarbons （HFC）, Chlorofluorocarbons （CFC） and Hydrocarbons （HC） with boiling points between -88.65 ℃ and 110.65℃. Net efficiency, which ranged from 0.1% to 25.8% in this work tends to increases with the temperature of the waste heat. Results of the present study demonstrate that working fluid R41 （with source temperature of 44 ℃） provides the maximum efficiency among those evaluated. Refrigerants R13B1 and R32 provide the best efficiency for waste heat source temperatures ranges 60 - 67 ℃ and 68 - 78℃ respectively. Ammonia shows the highest efficiency from 79℃ to 132 ℃. Refrigerants R31, R21, 17,30 and benzene perform well in the temperature ranges 133-151 ℃, 152-178 ℃, 179-236℃ and 237-250 ℃respectively. The optimal heat pump systems are applied to the hybrid copper sulfate-copper oxide thermochemical cycle for hydrogen production from water. 100.8 MW of electrical energy is produced, which increased the efficiency from 24.1% to 25.9%.

Selection of organic Rankine cycle working fluids in the low-temperature waste heat utilization

In the current study, simulations based on the engineering equation solver （EES） software are performed to determine the suitable working fluid for the simple organic Rankine cYcle system in different temperature ranges. Under the condition of various temperatures and a constant thermal power of the flue gas, the influence of different organic working fluids on the efficiency of the subcritical organic Rankine cycle power generation system is studied, and its efficiency and other parameters are compared with those of the regenerator system. It is shown that the efficiency of the subcritical organic Rankine cycle system is the best when the parameters of the working fluid in the expander inlet are in the saturation state. And for the organic Rankine cycle, the R245fa is better than other working fluids and the efficiency of the system reaches up to 10.2% when the flammability, the toxicity, the ozone depletion, the greenhouse effect and other factors of the working fluids are considered. The R60 l a working fluid can be used for the high-temperature heat source, however, because of its high flammability, new working fluid should be investigated. Under the same condition, the efficiency of the organic Rankine cycle power generation system with an internal heat exchanger is higher than that of the simple system without the internal heat exchanger, but the efficiency is related to the properties of the working fluid and the temperature of the heat source.

Performance Analysis of an Integrated Supercritical CO_(2) Recompression/Absorption Refrigeration/Kalina Cycle Driven by Medium-Temperature Waste Heat

A novel power and cooling cogeneration system which combines a supercritical CO_(2) recompression cycle(SCRC), an ammonia-water absorption refrigeration cycle(AARC) and a Kalina cycle(KC) is proposed and investigated for the recovery of medium-temperature waste heat. The system is based on energy cascade utilization, and the waste heat can be fully converted through the simultaneous operation of the three sub-cycles. A steady-state mathematical model is built for further performance study of the proposed system. When the exhaust temperature is 505℃, it is shown that under designed conditions the thermal efficiency and exergy efficiency reach 30.74% and 61.55%, respectively. The exergy analysis results show that the main exergy destruction is concentrated in the heat recovery vapor generator(HRVG). Parametric study shows that the compressor inlet pressure, the SCRC pressure ratio, the main compressor and the turbine I inlet temperature, and the AARC generator pressure have significant effects on thermodynamic and economic performance of the combined system. The findings in this study could provide guidance for system design to achieve an efficient utilization of medium-temperature waste heat(e.g., exhaust heat from gas turbine, high-temperature fuel cells and internal combustion engine).

某调度通信楼空调系统节能减碳改造设计实践

重点介绍了某调度通信楼空调系统的节能减碳改造设计,通过综合运用余热回收、可再生能源、固体蓄热、高效制冷机房等多项技术,构建了安全可靠、绿色低碳、高效节能的空调系统。采用HDY-SMAD空调负荷计算及分析软件模拟了建筑物全年的空调能耗,并对优化前后空调系统的运行能耗和碳排放进行了测算。结果显示,优化方案空调系统全年节约电量100万kW·h,全年碳减排573 t,节能减碳效果显著。

宽工况下水蒸气喷射制冷系统试验研究

针对低品位余热资源热负荷的不稳定性,开展研究利用低品位余热资源的水蒸气喷射制冷系统性能变化规律。通过搭建水蒸气喷射制冷试验平台,对蒸汽喷射器的引射系数与系统性能进行了试验研究。结果表明:当发生温度为设计温度140 ℃时,蒸汽喷射器引射系数与系统性能最佳,分别为0.34和0.33,当发生温度高于设计温度时,系统性能和蒸汽喷射器引射系数要比发生温度低于设计温度时更优;随着蒸发温度从2 ℃上升到22 ℃时,蒸汽喷射器引射系数由0.17上升到了0.22,增加了25%,系统性能从0.17上升到了0.24,提高了41%,因此较高的蒸发温度对系统的性能有所提升;系统存在1个临界冷凝温度,当超过临界冷凝温度时,蒸汽喷射器引射系数与系统性能急剧下降。研究结果为水蒸气喷射制冷的模拟研究提供了试验验证,对水蒸气喷射制冷系统的优化具有重要意义。

蒸汽溴化锂制冷应用于转炉中控楼的案例分析

转炉一次烟气通过汽化冷却烟道回收余热,从而产生大量蒸汽,该蒸汽最理想的应用场所就是转炉车间。以某转炉中控楼的蒸汽溴化锂制冷系统为例,主要介绍了中控楼的冷负荷分布、制冷系统的设计,以及相关的保障和辅助措施,并对电动制冷与蒸汽溴化锂制冷进行了比较。对于两座转炉所配套的中控楼,夏季冷负荷约为260kW,溴化锂制冷机组的蒸汽消耗量约为290kg/h。制冷站设置在中控楼附近,采用定流量水系统。制冷机组无需考虑备用,当制冷机组发生故障需要检修时,可临时采用机械通风的方式排除电气室余热。与电制冷相比,蒸汽溴化锂制冷的节电效果十分明显,可在1年以内收回初次投资。

工业低温余热回收利用研究进展

工业生产过程中产生的大量低温余热通过烟气、冷却介质等形式散发到环境中,将这些热能回收利用对提高能源利用率、促进实现“双碳”目标具有重要作用。文章通过详细回顾现有工厂利用低温余热的案例,对比不同热源条件下的换热方案及节能效果,得出低温余热具有余热制热、原材料预热及防冻、余热制冷、余热发电等广泛用途;指出在利用低温余热资源时,应重点关注热源的特点及工厂需求等方面,选择与企业适配的余热利用方式;并对低温余热在节能减排中发挥的重要作用提出展望。

工业余热回收系统优化策略原理

介绍有机朗肯循环发电系统在工业余热回收上的应用,选取某燃煤电厂为例,介绍其回收装置及节能分析,并在此基础上进行余热回收的优化策略分析。首先通过引入湿硫酸工艺,将烟气中的二氧化硫催化氧化为三氧化硫并在特殊换热器中冷凝并回收为硫酸副产品,以此打破烟气低品位余热深度利用的酸露点限制。然后通过有机朗肯循环和吸收式制冷集成的余热回收系统对烟气余热进行深度利用。通过数值模拟的方法对余热回收系统进行研究,通过模型验证确保数值模拟的可信度和准确性。

太阳能-余热联合驱动吸收过冷CO_(2)制冷-淡水联产系统性能分析

为了同时满足制冷和淡水的共同需求,提出了太阳能-余热联合驱动吸收过冷CO_(2)制冷-淡水联产系统(AbsCWCS),在提高CO_(2)制冷系统能效的同时可生产淡水。建立系统的热力学模型,分析了环境温度和太阳辐射强度对系统能效(COP)的影响。此外,为进一步分析气候条件的影响,选取5个典型缺水城市,对年度性能系数(APF)和年淡水产量进行了评估。结果表明:Abs-CWCS的COP和淡水产量均显著提升,与基础CO_(2)增压制冷-淡水联产系统(Base-CWCS)相比,COP提高了1.95%~41.02%,淡水产量增加了0.8~28.6倍,Abs-CWCS的CO_(2)制冷系统排气压力可降低7.86%;AbsCWCS可有效提高系统的APF,5个典型缺水城市的APF可提升3.66%,年淡水产量的提升率可达9.54%~64.62%。研究结果为同时解决制冷和淡水需求提供了可靠的解决方案。

余热回收型吸收式制冷循环系统的能效优化研究

在21世纪的能源利用领域,随着化石燃料的过度开采和资源紧张,人们不断寻找着一种高效、可持续的能源利用方式。面对这样的挑战,能源的回收和高效利用显得尤为关键。基于此,提出一种溴化锂吸收式制冷系统,该系统专门用于回收低温能源和工业废热等余热回收。首先,通过使用溴化锂水溶液的状态方程以及水和蒸汽的状态方程,建立了数学模型,以获取系统热力计算所需的状态参数;其次,将最大化性能面积比作为目标函数进行优化设计,明确了不同工作条件下各个热力学参数与系统性能之间的内在联系,计算了系统中各环节热力参数;最后,通过仿真分析的方法,对制冷系统中的关键参数进行了深入探讨,重点考察了那些可能对系统性能产生显著影响的因素,包括但不限于吸收剂浓度、循环泵速和热交换器效率等。结果表明:所设计的系统将热力系数提高了11.32%,同时总换热面积下降了1.82%。该系统成功地回收了废热并实现了制冷效果,展示了广泛的应用前景。

吸收式溴化锂机组回收蒸汽凝液余热制冷技术改造分析

介绍了余热回收溴化锂制冷机组的工作原理,针对鑫润公司60万t/a草酸技改乙二醇装置存在的1.0 MPa(G)蒸汽冷凝液大量直排、所含余热未进行利用的问题,进行了技术改造,即在乙二醇冷冻站新增吸收式溴化锂制冷机组系统,利用凝液余热制取冷冻水。改造后,热能浪费问题得到了有效解决,每年可节约电能2740.53万kW·h,相当于节约标准煤3368.11 t、减少CO_(2)排放量15629.24 t。

工业余热回收系统优化策略应用(上)

对于有机朗肯循环,首先进行工质筛选,从几种纯工质中筛选出最适合热源条件的两种作为非共沸工质的组分,并通过对比和优化选出了最佳工质混合比与蒸发压力。基于案例分析,整合工业余热回收系统设计及运行优化策略研究。使用VIKOR评价方法对使用不同工质的有机朗肯循环发电系统进行综合评估,证明优化方案能更好地综合权衡各项指标,取得满意的整体效果。在有机朗肯循环发电系统的基础上对烟气余热进一步优化回收,后接一个余热制冷系统组成余热梯级回收利用系统。对余热梯级回收利用系统进行了经济性分析,结果表明该系统具有良好的经济潜力。通过测算,可以看出采用余热梯级回收利用系统可以产生7698kW的电能以及24077kW的制冷量,系统投资可在4.89年内得以回收。

工业余热回收系统优化策略应用(下)

对于有机朗肯循环,首先进行工质筛选,从几种纯工质中筛选出最适合热源条件的两种作为非共沸工质的组分,并通过对比和优化选出了最佳工质混合比与蒸发压力。基于案例分析,整合工业余热回收系统设计及运行优化策略研究。使用VIKOR评价方法对使用不同工质的有机朗肯循环发电系统进行综合评估,证明优化方案能更好地综合权衡各项指标,取得满意的整体效果。在有机朗肯循环发电系统的基础上对烟气余热进一步优化回收,后接一个余热制冷系统组成余热梯级回收利用系统。对余热梯级回收利用系统进行了经济性分析,结果表明该系统具有良好的经济潜力。通过测算,可以看出采用余热梯级回收利用系统可以产生7698kW的电能以及24077kW的制冷量,系统投资可在4.89年内得以回收。

低温余热回收系统能量管理优化策略研究

低温余热回收系统在提高能源利用效率和减少排放方面具有重要作用。探讨了低温余热的来源、特性及其在不同行业中的应用潜力,分析了低温余热回收系统的设计方案和能量管理策略,综述了各种低温余热回收技术(如有机朗肯循环、吸收式制冷等)的原理及应用,指出现有系统在余热收集、传输和利用过程中存在的技术难题和效率瓶颈,提出了一系列创新的能量管理策略,旨在优化系统性能,包括改进热交换器设计、引入智能控制系统及采用多能源互补配置等。通过案例分析,验证了所提策略在提高系统能效、降低运营成本及促进可持续发展方面的有效性,此成果可为低温余热回收系统的设计与优化提供理论指导和实践参考,对推动能源高效利用和环境保护具有重要意义。

甲烷化装置余热回收增加发电机组

大唐国际克什克腾煤制天然气有限责任公司甲烷化装置,在甲烷化反应过程中,原料气经过脱硫和大量甲烷化反应后,经历第一补充甲烷化反应器71-C104后,出口工艺气温度设计操作值为449℃;经过原料气预热器(71-W102/2)、锅炉给水加热器(71-W109)后冷却至169℃;工艺气通过空冷器(71-W201)采用工艺气与空气的换热方式,控制工艺气温度。虽然空冷器具有节约用水量等优点,但仍然有大量热量不能被回收利用,为不将该部分热量浪费,可将其回收利用,以大幅降低装置能耗,节约生产成本。

石化企业炼油分部低温余热利用技术路线浅析

针对某石化4号柴油加氢装置精制柴油的低温热,采用热力循环计算方法分析了余热ORC技术的系统性能,并与余热加热锅炉给水和余热制冷方案进行了对比分析。结果表明,余热加热锅炉给水方案具有较高的能源利用效率,但其应用需进行全厂统筹规划;余热ORC发电方案经济性较高,应用灵活,无需考虑负荷匹配,经多年运行性能得到充分检验;余热制冷方案经济性稍差,应用受制于厂区制冷负荷需求。

聚酯酯化工艺塔余热综合利用

文章概述了在聚酯工艺塔装置中增加ORC发电机组配合溴化锂制冷回收酯化余热的相关研究。项目实施后,每年可节约用电约320万kWh,降低对煤炭的消耗,减少CO_(2)、粉尘、SO_(2)以及氮的氧化物的排放,改善了生态环境。