低温工艺热流体的分级冷却及控制研究

针对常规冷却方式和ORC发电冷却方式的缺陷,提出了低温工艺热流体的分级冷却系统;以某煤制油过程中的低温热流体工况为研究对象,计算了分级冷却系统的能耗情况,并与常规冷却方式和ORC发电冷却方式的能耗进行了对比,结果表明:分级冷却系统在工艺热流体冷却过程中,相比常规冷却方式,不仅不消耗额外的电能和水资源,反而产生发电收益,并且其发电功率远大于发电冷却方式的发电功率;最后,提出了低温工艺热流体分级冷却系统的控制方法。     

烧结余热技术的研究与应用

烧结工艺生产过程中产生大量的中低温余热资源,如何将这些资源变废为宝,有效利用,值得我们研究和探讨。文章分析了烧结余热的特点及回收利用技术,重点介绍了烧结余热发电技术,以供参考。     

水泥线纯低温余热发电安装项目市场分析

根据科学发展观的要求，国家加大了环境保护力度，节能环保项目已经成为国家这些年乃至今后经济建设的重要内容。这些年来，水泥纯低温余热发电项目在国内水泥行业得到大力推广几乎每条生产线都配套有余热发电项目，即保护了环境，又降低了生产成本，实现了经济效益和社会效益双赢。冶金行业也正在大力利用环冷机开发余热发电项目，玻璃行业余热的再利用项目也正在积极开发之中，可以说，余热发电安装项目的市场前景比较乐观。     

改进前后有机朗肯循环的热力学分析

有机朗肯循环是将低温余热转变为电能,进而提高总体能量利用率,减少污染排放的有效途径之一。本文提出了一种新的排汽回热再热式ORC,根据热力学第一定律和第二定律,利用EES软件仿真模拟对新ORC进行热力性能分析,并与基本ORC、排汽回热式ORC和再热式ORC进行相同条件下的性能对比,得出了新ORC具有最佳热力性能。通过研究再热压力、透平进口压力、透平进口温度和透平出口压力变化对新ORC性能的影响,得出了新ORC热力性能的优化方向。     

低温余热回收ORC系统工质的筛选

利用有机朗肯循环(ORC)技术高效回收低温余热的关键之一是选用合适的工质。本文针对热源温度介于120~220℃区间内的ORC系统,选用R123,R245fa,R600和R1233zd(E)四种工质为研究对象,通过对50 kW的ORC系统的运行分析并结合模拟计算,详细讨论不同工质的热力特性以及蒸发温度、蒸发压力、蒸发器出口过热度对ORC系统热效率的影响。结果表明,对于透平膨胀机入口工质温度在100~150℃区间、热源温度在120~220℃区间的低温余热回收ORC系统,工质R600性能表现最佳,但易燃;从不可燃性、热力特性、环境友好性及设备成本方面考虑,R1233zd(E)具有优势,但工质价格较高。     

中低温热水发电系统及效率分析

中低温热水发电通常选用有机朗肯循环系统。本文对ORC系统的特点、工质和参数的选择进行了介绍,并对系统进行效率分析。针对以80℃-150℃热水为热源的有机朗肯循环(ORC)发电系统,以?效率为评价指标,分析了循环工质为R134a、R123和R245fa时的系统。得出,R245fa是较为理想的工质。     

基于ORC的余热回收发电系统热力性能分析

本文建立了以R245fa为循环工质回收130℃余热的有机朗肯循环(ORC)发电系统,建立了系统各部件的能量和?分析模型,分析了不同冷凝压力、蒸发压力对系统各个部件的?损失和?效率、热效率的影响。结果表明:(1)蒸发压力增大:系统热效率和?效率提高,蒸发器?损失下降,冷凝器?损失增加,系统总?损失减少;(2)冷凝压力增大:系统热效率和?效率下降,蒸发器?损失下降,冷凝器?损失增加,系统总?损失增加。研究结果对指导ORC余热发电系统优化、实现提高系统整体性能、提高系统效率有重要意义。     

低压蒸汽余热发电应用研究

基于工程热力学理论,针对低压饱和蒸汽,建立了蒸汽直接膨胀系统、ORC余热发电系统、蒸汽直接膨胀联合ORC余热发电系统的计算模型,研究了蒸汽压力和回水温度对三种系统净发电量和发电效率的影响。结果表明:联合系统的净发电量最高;三种系统的净发电量和发电效率均随蒸汽压力的升高而升高,但ORC系统升高幅度较小;直接膨胀系统的净发电量和发电效率随回水温度的升高而急剧下降,其变化规律完全不同于另外两个系统。     

有机朗肯循环发电系统设计及实验研究

本文以90~150℃低温余热热源的回收利用为前提,搭建了有机朗肯循环(ORC)发电系统实验平台。通过调节透平膨胀机入口压力,改变蒸发温度,实验研究蒸发温度对膨胀机性能和系统性能的影响。结果表明:当蒸发温度从76℃升高到84℃时,膨胀机入口温度逐渐升高,使膨胀机转速增大约9.11%,膨胀机输出功率增大1.26 kW,最高等熵效率为80.6%;系统循环净功、热效率、不可逆损失及效率均随蒸发温度的升高呈增大趋势,分别增大了33.9%、26.7%、15.4%、27%。     

有机朗肯循环低温余热发电系统的工质选择

有机朗肯循环发电系统对于中低温余热的有效利用发挥了巨大的作用,但是有机朗肯循环系统的工质选择依旧是中低温余热利用中存在的问题。文章提出优选工质的条件,并通过对十种低沸点有机工质的性能对比分析得出R141b最适宜作为此温度的余热回收工质,综合性能高于其他工质,对于有机朗肯循环添加回热会大大提高系统效率。     

过冷度对地热发电非共沸工质有机朗肯循环热力性能的影响

有机朗肯循环（organic Rankine cycle,ORC）是利用中低温地热能（< 150℃）发电的主要途径,在实际运行中,非共沸工质往往会冷凝至过冷状态。分析了冷凝过冷度对非共沸工质ORC热力性能的影响,建立了ORC、内回热（internal heat exchanger,IHE）ORC的热力学模型,以净输出功最大为目标函数优化了工质的蒸发压力,并开展了系统的㶲分析。结果表明：过冷度影响了工质与冷源换热流体间的温度匹配特性,受夹点温差的限制,随着过冷度的增加,工质的冷凝压力上升;过冷度亦改变了预热器和蒸发器的热量分摊,随着过冷度的增加,最佳蒸发压力亦上升。混合工质异丁烷/异戊烷的质量配比为0.4：0.6时,净输出功受过冷度的影响最大,当过冷度为2℃时,净输出功下降了4.36%。IHE回收膨胀机排汽的余热,提高了预热器入口温度,可提高过冷ORC系统净输出功0.55%。过冷度增大了冷凝器的㶲损失;采用内回热冷凝器的㶲损失降低了24.7%。     

有机朗肯循环的发电系统的实验研究

以低温热蒸汽来模拟废热作为有机朗肯循环(ORC)的热源,建立了以R134a为制冷剂的有机朗肯循环发电系统。通过EES(engineering equation solver)软件对ORC系统进行了数学建模,并将实验与模拟结果进行了比较。结果表明:系统以R134a为工质运行,可以达到8%的发电效率;当膨胀机进口的状态为饱和或者过热时,系统的热效率与发电量都会随着进口压力的增加而增加;系统压力较低的时候,系统的不可逆程度较大,系统效率会有较大损失。     

Application of waste heat powered absorption refrigeration system to the LNG recovery process

The recovery process of the liquefied natural gas requires low temperature cooling, which is typically provided by the vapor compression refrigeration systems. The usage of an absorption refrigeration system powered by waste heat from the electric power generating gas turbine could provide the necessary cooling at reduced overall energy consumption. In this study, a potential replacement of propane chillers with absorption refrigeration systems was theoretically analyzed. From the analysis, it was found that recovering waste heat from a 9 megawatts (MW) electricity generation process could provide 5.2 MW waste heat produced additional cooling to the LNG plant and save 1.9 MW of electricity consumption. Application of the integrated cooling, heating, and power is an excellent energy saving option for the oil and gas industry.     

Analysis of recoverable waste heat of circulating cooling water in hot-stamping power system

This article studies the possibility of using heat pump instead of cooling tower to decrease temperature and recover waste heat of circulating cooling water of power system. Making use of heat transfer theory the article carried on analysis and calculation about recoverable waste heat of circulating cooling water in hot-stamping power system which includes hot-stamping, closing-in and extrusion intermediate frequency induction furnace. The results show that the whole process can recover a calorie which is 2.642 × 10⁶ kJ per hour. Using the recycled calories can make 15.82 tons hot water per hour which is 60 °C. So it can reduce burning capacity of coal 180.29 kg/h. The hot water can provide the needed water for production and workers bathing. This research shows that using heat pump to recover the waste heat of circulating cooling water is effectual. Realizing the use of waste heat, it can reduce pollution of condensing heat, reduce operating cost and noise of cooling tower, reduce site and the occupation of equipment, improve the production efficiency, and can also save the natural resources (fossil fuel-coal) and reduce the cost of needed hot water production.     

Investigation of an ammonia-water combined power and cooling system driven by the jacket water and exhaust gas heat of an internal combustion engine

An ammonia-water combined power and cooling system is proposed and investigated in this work, in which the waste heat contained in the jacket water and exhaust gas of an internal combustion engine can be recovered efficiently to generate power and cooling energy simultaneously. The proposed system was simulated, and its thermodynamic performance in the base case was calculated based on waste heat data from an actual gas engine with a rated power output of 300 kW. The equivalent heat-to-power efficiency of the combined system is 19.76%, and the total equivalent power output is as high as 92.86 kW. The exergy efficiency of the combined system reaches 33.69%. The effects of the turbine inlet pressure, generation pressure in the reboiler, exhaust gas temperature and cooling water temperature were studied to provide guidance for the system design. The results of an economic analysis indicate that the proposed system has good economic benefit.     

Design-theoretical study of cascade CO2 sub-critical mechanical compression/butane ejector cooling cycle

In this paper an innovative micro-trigeneration system composed of a cogeneration system and a cascade refrigeration cycle is proposed. The cogeneration system is a combined heat and power system for electricity generation and heat production. The cascade refrigeration cycle is the combination of a CO₂ mechanical compression refrigerating machine (MCRM), powered by generated electricity, and an ejector cooling machine (ECM), driven by waste heat and using refrigerant R600. Effect of the cycle operating conditions on ejector and ejector cycle performances is studied. Optimal geometry of the ejector and performance characteristics of ECM are determined at wide range of the operating conditions. The paper also describes a theoretical analysis of the CO₂ sub-critical cycle and shows the effect of the MCRM evaporating temperature on the cascade system performance. The obtained data provide necessary information to design a small-scale cascade system with cooling capacity of 10 kW for application in micro-trigeneration systems.     

Investigation of a mixed effect absorption chiller powered by jacket water and exhaust gas waste heat of internal combustion engine

CCHP (combined cooling heating and power) system based on ICE (internal combustion engine) has been widely used. A key issue is to efficiently recover the jacket water and exhaust gas waste heat for refrigeration. In this work, a mixed effect absorption chiller (AC), which couples single effect and double effect processes together, is investigated to recover these two kinds of waste heat simultaneously. The high pressure generator is powered by exhaust gas while one low pressure generator is powered by jacket water waste heat. Thermodynamic characteristics and off-design performance are simulated. Considering thermodynamic constraints, the start point temperature in low pressure generator should be 77°Cor lower. For a 16 kW ICE, the cooling output can reach 34.4 kW with COP of 0.96 and exergy efficiency of 0.186. Comparing with double effect or single effect AC, it can make a better use of different waste heat in CCHP system.     

DCCHP排烟余热耦合空气源热泵系统性能分析

内燃机冷热电联供系统作为一种高效的能源利用方式,排烟余热回收后的排放温度在100℃左右,仍有部分低温余热没有充分利用,提出一种分布式冷热电三联供（distributed combined cooling heating and power,DCCHP）动力排烟低温余热耦合空气源热泵系统,实现了排烟余热的深度回收。以10 kW内燃机冷热电联供为基础,研究了该系统可回收余热量、热泵循环性能系数（coefficient of performance,COP）以及对一次能源利用率的影响。结果表明：在设计工况下,DCCHP系统排烟余热1.22 kW,热泵系统回收余热量可达1.07 kW,排烟余热回收率达到87.7%;热泵COP高达4.66,提高39.5%;系统一次能源利用率提高3.9%;同时解决了寒冷地区冬季热泵机组蒸发器结霜、低温环境下运行性能差的问题。此研究为冷热电联供系统与热泵机组的联合高效应用提供了重要的参考。     

有机朗肯循环模拟及涡旋式膨胀机的性能研究

近些年来,太阳能作为一种可再生能源受到了广泛的关注。其中利用太阳能集热器实现100℃以下高效的热量回收,是一种普遍且有效的太阳能利用方式。采用有机朗肯循环与100℃的低温热源相结合进行发电,目前也逐渐受到了研究人员的关注。考虑到膨胀机是有机朗肯循环的核心部件,本文选择了R600制冷剂作为ORC系统的工质,对其进行了计算以及热力学性能分析。同时搭建了利用压缩空气来驱动的涡旋式膨胀机性能研究的实验台。从ORC的理论分析得,当热源温度为78~97℃,环境温度为30℃,可以获得0.7~1kW的电量,效率为0.84~0.89。利用压缩空气模拟R600,当温度从75℃变化到95℃,对应的压力从0.8MPa变化到1.2MPa,膨胀机出口压力控制在0.28MPa,等熵效率维持在0.7左右。膨胀机的功电转化效率随着膨胀机理想输出功的增加而降低。     

燃料电池分布式供能技术发展现状与展望

燃料电池作为一种清洁高效的发电方式,兼具效率高、排放低、安全无噪音等优点,是分布式供能领域的一项重要技术。燃料电池既可以利用传统煤炭、天然气,也可以融合可再生能源实现削峰填谷。在传统煤电领域,散煤的利用是环境污染的重要来源,通过直接碳燃料电池技术,有望解决散煤利用效率低下、污染严重的问题。联合天然气管网,基于燃料电池的微型热电联供系统可实现能源的梯级利用,相比传统的热电分供模式可大大提高能源利用效率。同时,电解池作为燃料电池的逆过程,可将可再生能源富余电力转化为化学能进行储存,实现"三弃"电力的有效转化,在可再生能源的分布式供应系统中具有广阔的发展前景。