A study on high flux heat exchanger used for low-temperature cogeneration system

doi:10.16085/j.issn.1000-6613.2018-0127

Abstract

Abstract: In this paper, high flux heat exchanger used for organic Rankine cycle (ORC) for low-temperature cogeneration system was studied. In the case of waste heat recovery of xylene tower in aromatic unit, six working fluids were used to analyze the influence of general evaporator pinch-point temperature difference on ORC system performance by Aspen Plus simulation software. Then, the generation performances of ORC system were compared when general evaporator and high flux evaporator were used separately. The results showed that the smaller pinch-point temperature difference of general evaporator is, the better generation performance of ORC system in aromatic unit is, but the evaporator area increases sharply when pinch-point temperature difference is less than 10℃, leading to higher costs and then limiting the generation performance boost of ORC system. The most suitable organic working fluid is R601 for ORC system, when the general evaporator pinch-point temperature difference is 12℃, the total heat transfer coefficient of high flux evaporator is more than 26% higher than that of general evaporator, and the application of high flux evaporator can reduce the heat transfer area by 21%. If the heat transfer area remains unchanged, the pinch-point temperature difference can decrease by 2.5℃, at this time, net generation power of ORC system can increase about 49kW, the reduction of R601 mass flow is 1559kg/h, so the generation performance has been improved.

Key words: organic Rankine cycle, waste heat recovery, high flux heat exchanger, aromatic unit, working fluid, pinch-point temperature difference

摘要： 针对高通量换热器用于有机朗肯循环（organic Rankine cycle，ORC）低温发电系统进行了理论研究，以芳烃装置二甲苯塔余热回收为实例，选取6种工质运用Aspen Plus模拟软件分析了普通光管蒸发器夹点温差对ORC系统的影响，并将使用高通量蒸发器时ORC系统的发电性能与使用普通蒸发器时进行了对比分析。结果表明：芳烃装置ORC发电系统蒸发器夹点温差越小，发电性能越好，但小于10℃后普通换热器面积急剧增大，成本升高，限制了ORC系统发电性能的提升。以最佳工质R601夹点温差12℃时作为基础工况，高通量蒸发器的总换热系数比普通蒸发器可增加26%以上，使用高通量蒸发器比普通蒸发器的换热面积减小21%，若换热面积保持不变，夹点温差可减小2.5℃，此时ORC系统的净输出功率可增加约49kW，R601流量减少1559kg/h，发电性能得到了提升。

关键词: 有机朗肯循环, 余热回收, 高通量换热器, 芳烃装置, 工质, 夹点温差

CLC Number:

TM617

YAO Yuting, LI Shiyu. A study on high flux heat exchanger used for low-temperature cogeneration system[J]. Chemical Industry and Engineering Progress, 2018, 37(10): 3737-3743.

姚玉婷, 李士雨. 高通量换热器用于低温发电系统的研究[J]. 化工进展, 2018, 37(10): 3737-3743.

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