Development and Evaluation of Hydrogen Energy System

氢作为一种能源载体具有极大的灵活性，因此在未来是一种极具吸引力的燃料。它也是一种清洁燃料，不含S， N和c。由龟山和吉田提出的UT-3（东京大学）循环由四种由Br， Ca和Fe化合物组成的固气反应组成。对该循环进行了一系列的动力学测量和经济评价，并建立了一个实验装置并成功运行，实现了连续制氢。在这些研究中，热源被假定为高温气体反应堆（HTGR）。另一方面，太阳能在未来的一个重要用途将是作为生产燃料和化学品过程的热源。太阳能热源与化学过程耦合的方式将极大地影响整个系统的成本和效率。在美国对太阳热-化学过程界面进行了各种研究。UT-…More 3循环包括两个高温吸热水解反应。这些反应是热化学循环的一部分，也起到储热系统的作用。基于这一观点，我们联合提出了一种生产速率为2000 Nm^3/h的UT-3循环太阳能热化学工艺的初步概念设计，并讨论了蒸汽加热器和两个吸热固定床反应器的热性能。该厂由以下子系统组成：(1)定日镜场子系统，(2)太阳能接收器子系统，(3)采用UT-3循环的热化学制氢子系统，(4)采用化学热泵的热回收子系统。仿真结果验证了暂态连续运行的可行性，并表明控制蒸汽流量可以有效补偿太阳热的变化。实验还表明，水解反应器既可以作为太阳能热的化学储存系统，也可以作为太阳能驱动的热化学循环的一部分。对制氢成本的初步分析表明，这将是非常有利的，UT-3循环与太阳能热结合在不久的将来可能有很大的潜力成为一个有竞争力的过程。少

Hydrogen is an attractive fuel for the future because of its great flexibility as an energy carrier. It is also a clean fuel and does not contain S, N and C. The UT-3 (the University of Tokyo) cycle proposed by Kameyama and Yoshida is composed by for four solid-gas reactions consisting of Br, Ca and Fe compounds.A series of kinetic measurements and economical evaluation have been already conducted for this cycle, and a bench-scale plant was constructed and successfully operated to produce hydrogen continuously. In these studies the heat source was supposed to be a high-temperature gas reactor (HTGR). On the otherhand, an important use of solar energy in the future will be as the heat source for processes which produce fuels and chemicals. The means by which the solar heat source is coupled to the chemical process will strongly influence both the cost and efficiency of the overall system. Various studies of the solar heat-chemical process interface have been conducted in the USA.The UT- … More 3 cycle includes two endothermic hydrolysis reactions at high temperature. These reactions are parts of the thermochemical cycle and also act as a thermal storage system. Based on this view, we did jointly proposed a preliminary conceptual design of a solar thermochemical process using the UT-3 cycle for the production rate of 2000 Nm^3/h, and discusses the thermal performance of the steam heater and two endothermic fixed bed reactors.The plant consists of the following subsystems : (1) Heliostat field subsystem, (2) Solar receiver subsystem, (3) Thermochemical hydrogen plant subsystem using the UT-3 cycle, (4) Heat recovery subsystem using a chemical heat pump. The simulation results demonstrated the feasibility bf continuous operation in the transient state and showed that the control of steam flow rate was effective to compensate for changes of incoming solar heat. It was also shown that the hydrolysis reactors can work well both as a chemical storage system for the solar heat and as the parts of solar driven thermochemical cycle.The preliminary analysis of hydrogen production cost showed that it would be very favourable and that the UT-3 cycle may have a great potential to become a competitive process in combination with solar heat in the near future. Less