Copper Chlorine Research Articles

Clean hydrogen production with the Cu–Cl cycle – Progress of international consortium, II: Simulations, thermochemical data and materials

This second of two companion papers presents the latest advances of an international team on the thermochemical copper–chlorine (Cu–Cl) cycle of hydrogen production. It specifically focuses on simulations, thermochemical data, advanced materials, safety, reliability and economics of the Cu–Cl cycle. Aspen Plus simulations of various system configurations are performed to improve the cycle efficiency. In addition, simulations based on exergo-economic and exergy-cost-energy-mass (EXCEM) methods for system design are presented. Modeling of the linkage between nuclear and hydrogen plants demonstrates how the Cu–Cl cycle would be integrated with an SCWR (Super Critical Water Reactor; Canada’s Generation IV reactor). Chemical potentials, solubilities, formation of Cu(I) and Cu(II) complexes and properties of Cu 2OCl 2, Cu(I) and Cu(II) chloride species are reported. In addition, the development of new advanced materials with improved corrosion resistance is presented. In particular, the performance of new anode electrode structures and thermal spray coatings is presented. This companion set of two papers presents new advances in a range of key enabling technologies for the thermochemical copper–chlorine cycle.

Byproducts and reaction pathways for integration of the Cu–Cl cycle of hydrogen production

The impact of exit streams containing byproducts of incomplete reactions in an integrated thermochemical copper–chlorine (Cu–Cl) cycle of hydrogen production is studied in this paper. In the hydrolysis reaction, CuCl 2reacts with steam to produce solid copper oxychloride. If the hydrolysis reaction does not proceed to completion, particles of un-reacted CuCl 2 will be transferred to a downstream molten salt reactor where oxygen is released from copper oxychloride decomposition. Undesirable chlorine may also be released as a result of CuCl 2 decomposition together with oxygen, resulting in a mass imbalance of the overall cycle. This paper also examines the implications of incomplete hydrolysis reactions on the kinetics and thermodynamics of the oxygen reactor in the Cu–Cl cycle, specifically the spontaneity of CuCl 2 decomposition and parameters that minimize the release of chlorine. Theoretical analysis of the decomposition of a mixture of CuO and CuCl 2 is also performed in this paper. It is found that usage of copper oxychloride is preferable over a mixture of CuCl 2 and CuO in the oxygen production reaction of the Cu–Cl cycle.

X-ray diffraction study of multiphase reverse reaction with molten CuCl and oxygen

The thermochemical copper–chlorine (Cu–Cl) cycle for hydrogen production includes three chemical reactions of hydrolysis, decomposition and electrolysis. The decomposition of copper oxychloride for oxygen production establishes the high-temperature limit of the cycle. At 450–530 °C, copper oxychloride (Cu 2OCl 2) decomposes to produce a molten salt of cuprous chloride (CuCl, copper I chloride) and oxygen gas. Minimization of the reverse reaction and undesirable products is critical for the proper operation of the Cu–Cl cycle. This paper examines the operating conditions that disfavor the reverse reaction of the oxygen production, and the parameters that maximize the extent of the forward reaction. Experiments were designed to disperse oxygen gas into a molten CuCl bath to study its reaction at 450–500 °C. The composition of the products was quantified with X-ray diffraction measurements. Experimental results indicate that a high decomposition extent of copper oxychloride is obtained at equilibrium when the temperature is higher than 500 °C, and the oxygen pressure is below 2 bar. The thermochemistry data of the reactants and products were also determined and reported. These thermodynamic data provide a key missing gap in the understanding of the Cu–Cl cycle of thermochemical hydrogen production. The data includes the standard formation entropy, enthalpy and Gibbs free energy at different temperatures. Also, in this paper, a thermodynamic analysis is performed to investigate the reverse reaction from the aspects of spontaneity and optimization of the operating parameters. It is found that the optimal operating parameters for minimizing the reverse reaction lie in the pressure range of 1–2 bar and a temperature range of 500–525 °C.

Exergy analysis of heat exchangers in the copper-chlorine thermochemical cycle to enhance thermal effectiveness and cycle efficiency

Most existing nuclear power plants in North America are typically water-cooled and operate at 250–500°C. For this temperature level, the copper–chlorine (Cu–Cl) cycle is one of the most promising cycles that can be integrated with nuclear reactors for hydrogen production by decomposing water into its constituents. In this study, we analyze the heat exchangers in the Cu–Cl thermochemical cycle so as to enhance heat transfer effectiveness and thereby improve the cycle efficiency. The thermal management options for internal and external heat transfer are studied and heat recovery opportunities are investigated and compared. Each heat exchanger in the cycle is examined individually based on the chemical/physical behavior of the process, and the most appropriate options are recommended. A thermodynamic analysis and associated parametric studies are performed for various configurations to contrast their efficiencies and effectivenesses.

Thermal design of a solar hydrogen plant with a copper–chlorine cycle and molten salt energy storage

In this paper, the operating temperature ranges of various solar thermal energy technologies are analyzed, with respect to their compatibility with solar hydrogen production via thermochemical cycles. It is found that the maximum temperature of 530 °C required by the oxygen production step in the Cu–Cl cycle can be supplied by current solar thermal technologies. The heat requirements are examined for the Cu–Cl cycle and it is found that the heat source must be sufficiently high and above the maximum temperature requirement of the Cu–Cl cycle, in order to match the heat requirements of the cycle. The quantity of molten salt and solar plant dimensions for capturing and storing solar heat for an industrial hydrogen production scale are also estimated for 24 h operation per day. The flow characteristics and heat losses of molten salt transport in pipelines are studied while considering the influences of pipeline diameter, heat load and weather conditions. The heat loss from a solar salt storage tank is also calculated based on various tank diameters and heights. The intermediate product of molten salt produced in the oxygen production step gives the Cu–Cl cycle a significant advantage of linkage with current high temperature solar thermal technologies. This allows flexibility for integration of the Cu–Cl cycle and solar thermal plant. Using a thermal network analysis of the Cu–Cl cycle, the layout options for the integration of a Cu–Cl cycle with various solar thermal technologies are presented and discussed in this paper.

Integrated gasification and Cu–Cl cycle for trigeneration of hydrogen, steam and electricity

This paper develops and analyzes an integrated process model of an Integrated Gasification Combined Cycle (IGCC) and a thermochemical copper–chlorine (Cu–Cl) cycle for trigeneration of hydrogen, steam and electricity. The process model is developed with Aspen HYSYS software. By using oxygen instead of air for the gasification process, where oxygen is provided by the integrated Cu–Cl cycle, it is found that the hydrogen content of produced syngas increases by about 20%, due to improvement of the gasification combustion efficiency and reduction of syngas NO x emissions. Moreover, about 60% of external heat required for the integrated Cu–Cl cycle can be provided by the IGCC plant, with minor modifications of the steam cycle, and a slight decrease of IGCC overall efficiency. Integration of gasification and thermochemical hydrogen production can provide significant improvements in the overall hydrogen, steam and electricity output, when compared against the processes each operating separately and independently of each other.

Exergoeconomic analysis of a hybrid copper–chlorine cycle driven by geothermal energy for hydrogen production

In this study, we conduct an exergy, cost, energy and mass (EXCEM) analysis of a copper–chlorine thermochemical water splitting cycle driven by geothermal energy for hydrogen production. We also investigate and illustrate the relations between thermodynamic losses and capital costs. The results show that hydrogen cost is closely and directly related to the plant capacity and also exergy efficiency. Increasing economic viability and reducing the hydrogen production costs will help these cycles play a more critical role in switching to hydrogen economy.

Pressure drop of packed bed vertical flow for multiphase hydrogen production

In this paper, fluid flow characteristics through a packed bed reactor are investigated. The packed bed is utilized in the hydrogen production step of the copper–chlorine (Cu–Cl) thermochemical cycle. The hydrogen reaction is given by 2Cu(s) + 2HCl(g) = 2CuCl(molten) + H 2(g) at 450 °C. Effectively controlling the pressure drop through the packed bed is important for increasing the system efficiency, since auxiliary pumps and other parasitic losses are affected by the pressure drop. Also, the chemical processes in the packed bed are affected by changes in pressure, temperature and heat transfer rates. Experimental results from a laboratory scale packed bed reactor, operating at ambient conditions, are presented and compared with analytical predictions, in terms of the pressure drop caused by fluid flow through the packing material. Three different packing materials, with various sphericities, are investigated with diameters of 450 μm, 4 mm, and 1 cm. The Ergun equation is shown to provide good agreement for flow conditions in the upper region of Reynolds numbers investigated (20 < Re p < 150); however, lack of agreement is observed at lower Reynolds numbers (Re p < 20). An analytical formulation for micro scale particles in a packed bed is developed based on the Stokes law for creeping flow. Good agreement is achieved with the corresponding experimental data. A new correction is also developed to connect the two flow regimes, as well as predict trends in the transition region. The results successfully demonstrate close agreement between the predictions and measured data.

Potential thermochemical and hybrid cycles for nuclear-based hydrogen production

This paper discusses some potential low-temperature thermochemical and hybrid cycles for nuclear-based hydrogen production and considers them as a sustainable option for hydrogen production using nuclear process/waste heat and off-peak electricity. We also assess their thermodynamic performance through energy and exergy efficiencies. The results show that these cycles have good potential and become attractive due to their high overall efficiencies 50% based on a complete reaction approach. The copper–chlorine cycle appears to be a highly promising cycle for nuclear-based hydrogen production in this regard. Copyright © 2010 John Wiley & Sons, Ltd.

Convective heat transfer and solid conversion of reacting particles in a copper(II) chloride fluidized bed

This paper develops a predictive model of convective heat transfer and conversion of cupric chloride particles in a fluidized bed reactor of a copper–chlorine (Cu–Cl) cycle of thermochemical hydrogen production. The hydrolysis reaction of particles in the fluidized bed is endothermic and it requires excess steam for complete conversion of cupric chloride solid. The excess steam supply may be used for partial heat supply to the endothermic reaction, and also to avoid defluidization in the bed. To avoid defluidization, the change of gas flow in the bed due to the reaction should be minimized at a given operating condition. The model predicts the maximum possible steam inlet temperature, steam conversion, amount of partial heat supply, and also gas flow rates through the bed to avoid defluidization. The new model presents significant new insight by analyzing the hydrodynamic and mass transport processes, considering the equilibrium limitation on the conversion of cupric chloride solid. The model results indicate that the chemical reaction requires a high mole ratio of steam for complete conversion of cupric chloride particles. The maximum steam conversion is limited by temperature, pressure, and the presence of hydrogen chloride gas. The maximum conversion of steam at 400°C is 3.75% and it requires excess steam of 12.8 moles per unit mole of cupric chloride solid for complete conversion of solid. The heat supply by steam for the reaction, as well as raising the solid feed to the reaction temperature, varies with reaction temperature. The paper also adds significant new insight by analyzing the steam flow requirement in terms of temperature, conversion rate, and quality of fluidization. Additional new results are presented and applications discussed for the Cu–Cl cycle of nuclear hydrogen production.

Analysis of the Corrosion Products of the Ancient Bronzes Excavated from Qiaojiayuan Tombs

XRD, Raman analysis, and metallographic analysis are used to identify corrosion products of ancient bronzesexcavated from Qiaojiayuan tombs, and the result indicates that the corrosion products mainly includesCu2CO3(OH)2, Cu3(OH)2(CO3)2, Cu2O, Cu2Cl(OH)3, CuCl2·2H2O, PbCO3 and SiO2. It was found that theseancient bronzes were preserved in a chloric, acidity, and seasonal changed environment. In addition, the ? phaseof the eutectoid was corroded preferentially in this environment. There are lots of corrosion types in thesebronzes, such as electrochemistry corrosion, hole-corrosion, and dot-corrosion. The corrosion products generallyhave copper oxychloride, moisture copper chloride and other copper chlorination corrosions, and the position ofthe powdery corrosion presents the rust layer structure of “copper- cuprite- paratacamite- malachite- azurite”. Atthe same time, the corrosion principles of the bronzes are discussed, and the simple methods scientificallyprotecting these bronzes are suggested in the final part of the article.

Processing oxide-sulfide copper ores using ammonium chloride

The method of processing copper raw material into copper oxide is suggested and investigated. This method is based on the decomposition of copper oxide and sulfide by ammonium chloride with the subsequent leaching of chloride compounds of copper and the precipitation of copper hydroxide from the solution. The thermodynamics is calculated, and a thermogravimetric analysis of the processes is carried out. The kinetics of chlorination of copper and iron sulfides, as well as calcium oxide with ammonium chloride, is investigated experimentally. A process flowsheet of the closed cycle of processing the copper-containing raw material using ammonium chloride is suggested.

Greenhouse gas reduction in oil sands upgrading and extraction operations with thermochemical hydrogen production

This paper examines various methods of reducing CO 2 emissions by a thermochemical copper–chlorine (Cu–Cl) cycle of hydrogen production, for in-situ extraction and upgrading of bitumen to synthetic crude oil in Alberta’s oil sands. Particular focus is given to Canada’s SCWR (Supercritical Water-cooled Reactor) as a nuclear heat source for the Cu–Cl cycle, although other heat sources such as solar or industrial waste heat can be utilized. The feasibility of steam generation from supercritical water of a SCWR power plant is examined for bitumen extraction, as well as hydrogen production for bitumen upgrading via an integrated Cu–Cl cycle with SCWR. The heat requirements for bitumen extraction from the oil sands, and the hydrogen requirements for bitumen upgrading, are examined. A new layout of oil sands upgrading operations with integrated SCWR and a Cu–Cl cycle is presented. The reduction of CO 2 emissions due to the integrated SCWR and Cu–Cl cycle is quantitatively investigated based on the expected bitumen production capacity over the next two decades.

Vapor compression CuCl heat pump integrated with a thermochemical water splitting cycle

In this paper, the feasibility of using cuprous chloride (CuCl) as a working fluid in a new high temperature heat pump with vapor compression is analyzed. The heat pump is integrated with a copper–chlorine (Cu–Cl) thermochemical water splitting cycle for internal heat recovery, temperature upgrades and hydrogen production. The minimum temperature of heat supply necessary for driving the water splitting cycle can be lowered because the heat pump increases the working fluid temperature from 755 K up to ∼950 K, at a high COP of ∼6.5. Based on measured data available in past literature, the authors have determined the T– s diagram of CuCl, which is then used for the thermodynamic modeling of the cycle. In the heat pump cycle, molten CuCl is flashed in a vacuum where the vapor quality reaches ∼2.5%, and then it is boiled to produce saturated vapor. The vapor is then compressed in stages (with inter-cooling and heat recovery), and condensed in a direct contact heat exchanger to transfer heat at a higher temperature. The heat pump is then integrated with a copper–chlorine water splitting plant. The heat pump evaporator is connected thermally with the hydrogen production reactor of the water splitting plant, which performs an exothermic reaction that generates heat at 760 K. Additional source heat is obtained from heat recovery from the hot reaction products of the oxy-decomposer. The heat pump transfers heat at ∼950 K to the oxy-decomposer to drive its endothermic chemical reaction. It is shown that the heat required at the heat pump source can be obtained completely from internal heat recovery within the plant. First and second law analyses and a parametric study are performed for the proposed system to study the influence of the compressor's isentropic efficiency and temperature levels on the heat pump's COP. Two new indicators are presented: one represents the heat recovery ratio (the ratio between the thermal energy obtained by internal heat recovery, and the energy needed at the heat pump evaporator), and the other is the specific heat pump work per mole of hydrogen produced. This new heat pump with CuCl as a working fluid can be attractive in other industrial contexts where high temperature heat is needed. One may replace a common heating technology (combustion or electric heating) with the present sustainable method that uses heat recovery and high efficiency temperature upgrading for heating applications.

ChemInform Abstract: A Study of the Chlorination of Copper(I) and Copper(II) Oxides

ChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 100 leading journals. To access a ChemInform Abstract of an article which was published elsewhere, please select a “Full Text” option. The original article is trackable via the “References” option.

Canada’s program on nuclear hydrogen production and the thermochemical Cu–Cl cycle

This paper presents an overview of the status of Canada’s program on nuclear hydrogen production and the thermochemical copper–chlorine (Cu–Cl) cycle. Enabling technologies for the Cu–Cl cycle are being developed by a Canadian consortium, as part of the Generation IV International Forum (GIF) for hydrogen production with the next generation of nuclear reactors. Particular emphasis in this paper is given to hydrogen production with Canada’s Super-Critical Water Reactor, SCWR. Recent advances towards an integrated lab-scale Cu–Cl cycle are discussed, including experimentation, modeling, simulation, advanced materials, thermochemistry, safety, reliability and economics. In addition, electrolysis during off-peak hours, and the processes of integrating hydrogen plants with Canada’s nuclear plants are presented.

Dynamic flowgraph modeling of process and control systems of a nuclear-based hydrogen production plant

Modeling and analysis of system reliability facilitate the identification of areas of potential improvement. The Dynamic Flowgraph Methodology (DFM) is an emerging discrete modeling framework that allows for capturing time dependent behaviour, switching logic and multi-state representation of system components. The objective of this research is to demonstrate the process of dynamic flowgraph modeling of a nuclear-based hydrogen production plant with the copper–chlorine (Cu–Cl) cycle. Modeling of the thermochemical process of the Cu–Cl cycle in conjunction with a networked control system proposed for monitoring and control of the process is provided. This forms the basis for future component selection.

Natural gas usage as a heat source for integrated SMR and thermochemical hydrogen production technologies

This paper investigates various usages of natural gas (NG) as an energy source for different hydrogen production technologies. A comparison is made between the different methods of hydrogen production, based on the total amount of natural gas needed to produce a specific quantity of hydrogen, carbon dioxide emissions per mole of hydrogen produced, water requirements per mole of hydrogen produced, and a cost sensitivity analysis that takes into account the fuel cost, carbon dioxide capture cost and a carbon tax. The methods examined are the copper–chlorine (Cu–Cl) thermochemical cycle, steam methane reforming (SMR) and a modified sulfur–iodine (S–I) thermochemical cycle. Also, an integrated Cu–Cl/SMR plant is examined to show the unique advantages of modifying existing SMR plants with new hydrogen production technology. The analysis shows that the thermochemical Cu–Cl cycle out-performs the other conventional methods with respect to fuel requirements, carbon dioxide emissions and total cost of production.

Convective heat transfer from molten salt droplets in a direct contact heat exchanger

This paper presents a new predictive model of droplet flow and heat transfer from molten salt droplets in a direct contact heat exchanger. The process is designed to recover heat from molten CuCl in a thermochemical copper–chlorine (Cu–Cl) cycle of hydrogen production. This heat recovery occurs through the physical interaction between high temperature CuCl droplets and air. Convective heat transfer between droplets and air is analyzed in a counter-current spray flow heat exchanger. Numerical results for the variations of temperature, velocity and heat transfer rate are presented for two cases of CuCl flow. The optimal dimensions of the heat exchanger are found to be a diameter of 0.13 m, with a height of 0.6 and 0.8 m, for 1 and 0.5 mm droplet diameters, respectively. Additional results are presented and discussed for the heat transfer effectiveness and droplet solidification during heat recovery from the molten CuCl droplets.

Solar thermochemical plant analysis for hydrogen production with the copper–chlorine cycle

In this article, a solar-based method of generating hydrogen from the copper–chlorine water-splitting cycle is developed and evaluated. An analysis is performed for solar plants with different hydrogen production capacities at three locations across Canada. Operating parameters of the solar field and the storage units are presented. The thermal efficiency and cost parameters of the hydrogen plant are also examined. A binary mixture of 60% NaNO 3 and 40% KNO 3 is used as the molten salt for solar energy storage. Different hydrogen production rates are analyzed. Since the solar irradiation in Calgary is much less than Toronto and Sarnia in the winter, it is found that a larger storage unit is required. The size of the storage unit increases for larger hydrogen production rates. The results support the feasibility of solar thermochemical Cu–Cl cycle as a promising and efficient pathway for large-scale production of hydrogen.