Reliability assessment of a hydrogen reactor unit of copper-chlorine thermochemical cycle

Thermochemical water splitting is a promising method for large-scale hydrogen production. One of the thermochemical water splitting methods, the Copper-Chlorine (Cu-Cl) thermochemical cycle, has been receiving considerable attention for long-term sustainable hydrogen production. In the Cu-Cl cycle, heat input is used to dissociate water into hydrogen and oxygen. The process is composed of five reaction steps, which are achieved in respective reactor units including the hydrogen reactor, the electrochemical cell, the spray drying unit, the fluidized bed unit and then oxygen reactor. Each reactor unit is equipped with its respective Instrumentation and Control (I and C) systems to control the reaction process. The I and C systems consist of actuators, controllers and sensors which are connected together through a communication network. The malfunction of I and C systems, especially the unavailability of the control network, can jeopardize the stability of the control system and lead to safety concerns. In this paper, the design of the I and C systems for the hydrogen reactor is presented by creating a Piping and Instrumentation Diagram (P and ID). The design aims at maintaining controllable operation and enhancing reactor safety. The impact of I and C systems malfunction, especially the communication network failure, on process reliability is qualitatively analyzed using a fault tree. This supplies key information on component selection and, inspection and maintenance strategies determination, in order to increase system life cycle, reduce reactor failure frequency and improve system safety. (author)