Development and Evaluation of Hydrogen Energy System

氢是一种极具吸引力的未来燃料，因为它作为能源载体具有极大的灵活性。它也是一种清洁燃料，不含S、氮和碳。龟山和吉田提出的UT-3(东京大学)循环是由四个由溴、钙和铁化合物组成的固气反应组成的。已经对该循环进行了一系列的动力学测试和经济评价，并建成并成功地运行了连续制氢的小试装置。在这些研究中，热源被认为是高温气体反应堆(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的过程的热源。太阳能热源与化学过程的耦合方式将极大地影响整个系统的成本和效率。美国已经对太阳能热-化学过程界面进行了各种研究。UT-…3个以上的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，也是一个储热系统。基于这一观点，我们共同提出了利用UT-3循环的太阳能热化学过程的初步概念设计，并讨论了蒸汽加热器和两个吸热式固定床反应器的热性能。该装置由以下几个子系统组成：(1)定日场子系统，(2)太阳能接收子系统，(3)采用UT-3循环的热化学制氢厂子系统，(4)采用化学热泵的热回收子系统。仿真结果表明，在过渡状态下连续运行是可行的，蒸汽流量的控制可以有效地补偿入射热的变化。初步的制氢成本分析表明，UT-3制氢循环是一种非常有利的制氢方式，UT-3制氢循环在不久的将来很有可能成为一种与太阳能相结合的具有竞争力的制氢工艺。较少

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