Hydrogen-oxygen steam generator for a closed hydrogen combustion cycle

摘要

The paper deals with the problems of hydrogen combustion in an oxygen environment to produce high-temperature steam to be used in electricity generation at various power stations including nuclear power plants (NPP). For example, the use of H-2/O-2 steam generator within a hydrogen energy complex may allow increasing the NPP power and efficiency under operating conditions due to hydrogen steam superheating of the main working fluid in a steam-turbine unit. In addition, the use of the hydrogen energy complex may allow adapting NPP to variable electric load schedules with the increasing share of such power stations as well as developing environmentally friendly technologies for electricity generation. In the paper, a new solution to the problem of the effective and safe use of hydrogen energy at NPP with a hydrogen energy complex has been proposed.Technical solutions to hydrogen combustion in an oxygen environment using direct injection of cooling water or water steam into combustion products may have a significant weakness, namely the "quenching" phenomenon occurring during water/water steam injection resulting in the recombination efficiency decrease during the cooling of combustion products which is reflected in the increased proportion of non-condensable gases. In this case, the supply of such mixture to the steam-power cycle may be unsafe, as it could result in the increased concentration of unburned hydrogen in the steam turbine flow path. In the paper, a closed hydrogen cycle along with the hydrogen steam superheating system on its basis has been proposed to solve this problem. The closed-circuit system of hydrogen combustion preventing hydrogen permeation into the working fluid of a steam cycle completely as well as ensuring its full oxidation due to some excess of circulating oxygen has been investigated by the authors.Two types of H-2/O-2 combustion chambers for the system of safe hydrogen steam superheating in NPP cycle by using the closed-circuit system of hydrogen combustion in an oxygen environment have been considered in the study. The required parameters of H-2/O-2 steam generator with regard to operating temperature conditions as well as the power range of H-2/O-2 steam generators with the proposed combustion chamber construction design have been determined by mathematical modeling of the combustion and heat mass-exchange processes. (C) 2019 Hydrogen Energy Publications LLC. Published by Elsevier Ltd. All rights reserved.