Cu Cl Cycle Research Articles

Analysis of the viability of the 2 × 250 MWth HTR-PM project for the hydrogen production by the high temperature electrolysis and the Cu-Cl cycle

The work describes two proposals for hydrogen production using the HTR-PM reactor as an energy source. Both proposals take advantage of the high output temperatures of the 2 × 250 MWth HTR-PM project to increase the efficiency of hydrogen production processes. Two proposals are analysed, the hydrogen production through the Cu-Cl cycle and the high temperature electrolysis process. To evaluate the efficiency of the proposed conceptual designs, two computational models were developed in a chemical process simulator. A determination of the efficiency of the hydrogen production process coupled to the HTR-PM was carried out using the computational model developed. The high temperature electrolysis (HTE) process can produce 0.7821 kg/s of hydrogen with 27.37% of efficiency. The Cu-Cl process, although producing less hydrogen, 0.5637 kg/s, has higher overall efficiency (32.12%) than the HTE, mainly due to less global exergy destruction and higher exergetic efficiency.

Analysis of the viability of the 2 × 250 MWth HTR-PM project for the hydrogen production by the high temperature electrolysis and the Cu-Cl cycle

Analysis of the viability of the 2 × 250 MWth HTR-PM project for the hydrogen production by the high temperature electrolysis and the Cu-Cl cycle

A new approach in treating industrial hazardous wastes for energy generation and thermochemical hydrogen production

Abstract A new configuration of using hazardous industrial waste incineration system for energy generation and hydrogen production is proposed in this study. A heat recovery steam generator is used to generate steam for the double-stage Rankine cycle for electrical power generation. The additional heat from the incineration unit exhaust gas are employed to generate steam for the thermochemical Cu-Cl cycle. The CO2 emissions carried by the incineration reactor exhaust gases are captured using aqueous ammonia-based carbon capturing system. The Aspen Plus V9 software is employed for the designed system simulation. Numerous sensitivity studies are undertaken to investigate each subsystem of the proposed hazardous industrial waste incineration system. The proposed system generates 7.08 MW of electrical output and hydrogen production flowrate of 12.6 kmol/h. The exergetic and energetic efficiencies of the designed system are found to be 43.3% and 39.1%. Furthermore, the sensitivity analysis results are presented and discussed. The incineration plants treating the waste and converting waste into energy can be substituted for conventional energy production and this proposed environmentally benign integrated system will resolve environmental problems by employing the hazardous industrial waste to the new configuration of the incineration process for producing hydrogen and power with zero CO2 emissions.

Analytical prediction of heat capacity of molten AgCl and CuCl with application to thermochemical Cu-Cl cycle for hydrogen production

To sustain our power-dependent world, there is a need for technological innovation in all aspects of science and engineering. Many times, thermophysical and material properties are not well defined for the specific application, which leads to implementing assumptions and approximations from the published data. In the thermochemical copper-chlorine (Cu-Cl) cycle for hydrogen (H2) production, heat is recovered from cuprous chloride (CuCl) molten salt and it is then reacted with hydrochloric acid (HCl) in stoichiometric proportions to produce the anolyte for the H2 production step of the cycle. However, the lack of precise thermophysical properties on CuCl heavily hinders the detailed investigations of heat recovery from the molten salt as it cools from 450 °C to 90 °C. In this paper a new method is developed to determine the thermophysical property of CuCl and silver chloride (AgCl) as the molten salts are changing phases to solid. This is achieved by correlating electrochemistry data with thermal data. A model that predicts the specific heat capacity during phase change process is developed based on the existing electromotive force (EMF) and thermal data from literature. Developed model shows the EMF derived specific heat capacity values of AgCl and CuCl are similar with a slight offset since they have similar EMF's at higher temperatures.

Azeotropic Separation of HCl-Water by Pressure Swing Distillation: Steady State Simulation and Economic Optimization

Copper-Chlorine (Cu-Cl) thermochemical cycle for hydrogen production involves decomposition of water into hydrogen and oxygen with the use of intermediate copper and chlorine compounds and all other reactants are regenerated and recycled to create a closed loop. Our ongoing investigations on copper-chlorine (Cu-Cl) cycle involve electrochemical and thermal reactions constituting six steps. Hydrolysis of cupric chloride to copper oxide and dry hydrogen chloride (HCl) gas is one of the crucial steps. This involves non-catalytic reaction of cupric chloride and steam between 350 and 400oC which needs excess steam for complete conversion of cupric chloride thereby resulting formation of dilute hydrochloric acid rather than dry HCl gas which needs to be recycled to hydrogen generation. Therefore, azeotrope between the HCl and water needs to be eliminated. This work has proposed design and optimization of pressure swing distillation (PSD) for separation of HCl -water by using heat integration of two columns operating at different pressures and temperatures. The first column operating at low pressure concentrates the feed up to the azeotropic point and second column operating at high pressure eliminates the azeotrope and generates dry HCl gas. The reboiler heat of high pressure column (HPC) is reutilized to heat the low pressure column (LPC) and HPC feed which reduces the total annual cost (TAC). Heat integration saves an energy cost by 11.03% of and total annual cost by 6.83 % as compared to non-heat integrated PSD system. Feed composition has strong impact on energy and ultimately economics.

Exergoeconomic and multi-objective optimization of a solar thermochemical hydrogen production plant with heat recovery

A solar hydrogen production plant based on a four-step copper-chlorine (Cu-Cl) thermochemical cycle is presented and analyzed in this paper. The integrated system includes a pressurized solar power tower, gas turbine unit, phase change material (PCM) for thermal energy storage (TES), Cu-Cl cycle, regenerative steam Rankine cycle (SRC), and a heat recovery unit. A predictive model is developed for energy, exergy, and exergo-economic analyses of the proposed system. A parametric study is also conducted to investigate the effect of major parameters on the system performance. The system is optimized with a non-dominated sorting genetic algorithm-II (NSGA-II) considering exergy efficiency and product cost per unit exergy as the two objective functions. The results indicate that the energy and exergy efficiencies of the overall system are 48.2% and 45%, respectively, while the total product cost per unit of exergy is found to be $10.97/GJ. The integrated solar system produces hydrogen, electricity, and steam at a rate of 0.1 kg/s, 50.49 MW, and 13.93 kg/s, respectively. Pareto solutions for multi-objective optimization indicate that the optimal design point of the system has an exergy efficiency and total product cost per unit of exergy of 50.1% and $11.94/GJ, respectively.

Development and multi-objective optimization of a newly proposed industrial heat recovery based cascaded hydrogen and ammonia synthesis system

The industrial flue gas emitted to the atmosphere is considered not only harmful to the environment but also a waste of plentiful resources of thermal energy. The thermal energy extracted from the industrial flue gas can be employed for multiple purposes. This study proposes a new configuration to integrate the thermal management of industrial flue gas for thermochemical copper-chlorine (Cu-Cl) cycle based ammonia synthesis. A reverse osmosis desalination unit is employed to supply the freshwater required by the thermochemical Cu-Cl cycle. To recover the heat from high-temperature oxygen stream, thermoelectric generators (TEGs) and organic Rankine cycle (ORC) are integrated with the proposed configuration to utilize the low-grade waste heat for power production. A portion of produced hydrogen through the thermochemical Cu-Cl cycle is supplied to the cascaded system for ammonia production. A double-stage cascaded ammonia synthesis system is integrated with the proposed configuration to achieve high fractional conversion. A multi-objective optimization using genetic algorithm is implemented to the proposed system using the MATLAB to investigate and determine the best-operating temperatures and pressures for the ammonia synthesis system. The proposed configuration produces 518.4 kmol/day of hydrogen and 226.8 kmol/day of ammonia. The overall exergetic and energetic efficiencies are found to be 28.7% and 40.8%. Moreover, the results obtained from the comprehensive sensitivity analyses are presented and discussed.

Waste-to-hydrogen: Recycling HCl to produce H2 and Cl2

Coal-fired power plants are the most common form of power generation in many regions, which continuously produce waste heat and hydrogen chloride (HCl) flue gas. To address this issue, a novel Cu-Cl hydrogen production cycle is modeled to recycle industrial waste heat and exhaust HCl and to produce hydrogen, realizing the waste-to-hydrogen (WtH) process. To complement the process analysis, a gate-to-gate life cycle emission analysis and gate-to-grave cost-benefit analysis have been performed to evaluate the commercial feasibility and environmental impacts. The final results of the product cost and life cycle CO2 emission of this Cu-Cl cycle are 2.8 US dollars/kg H2 and 8.7 kg CO2/kg H2, respectively. Cu-Cl cycle offers an economically competitive option compared with the steam methane reforming (SMR) hydrogen production process if taking the benefit of Cl2 into account. The life cycle CO2 emission of the Cu-Cl cycle is less than other existing processes, as the process can consume a considerable amount of HCl gas, which is regarded as greenhouse gas as well. The proposed process is shown to be a promising alternative to conventional hydrogen production processes.

A comparative evaluation of OTEC, solar and wind energy based systems for clean hydrogen production

Abstract In this article, three different renewable energy methods are considered with wind, ocean thermal energy conversion (OTEC) and solar energy for clean hydrogen production, and Cu-Cl based thermochemical cycle is incorporated into systems to develop potential applications. In the proposed CuCl cycle configuration, the additional heat offered after the thermolysis reactor is recovered to heat the water before reaching the hydrolysis reactor. In the wind energy based hydrogen production system, the maximum exergy destruction rate is found to be 48.3 kW in the wind turbine. The turbine employed to the ocean thermal energy conversion system is found to be undergoing the highest exergy destruction rate of 143.3 kW. The energy and exergy efficiencies of the solar energy based thermochemical CuCl cycle are found to be 32.7% and 33.2% and the maximum exergy destruction rate of 350.69 kW is offered by the thermolysis reactor. The energetically improved configuration of the thermochemical CuCl cycle displays promising results compared to the earlier studies, such as lower heat requirements and higher efficiencies. The study indicates that there is a value to develop a clean OTEC based hydrogen production system and implement for practical applications. Furthermore, some sensitivity analyses are performed to investigate the performance of each system under different operating parameters and discussed.

Kinetic and hydrodynamic analyses of chemically reacting gas-particle flow in cupric chloride hydrolysis for the Cu-Cl cycle

The non-catalytic reaction of cupric chloride with steam to produce copper-oxy-chloride solid and hydrogen chloride gas is one of the most challenging steps in the copper-chlorine (Cu–Cl) thermochemical water splitting cycle of hydrogen production. Researchers at the University of Ontario Institute of Technology have designed a reactor in which a CuCl2 (aq) solution is atomized and reacted in a furnace where superheated steam is drawn in a counter-current stream. This study develops a new predictive model of the transport mechanisms of the hydrolysis reaction to predict the conversion of CuCl2(s) into the products. The hydrodynamic model estimates the residency time of the reactants in the reaction, and the kinetics predicts the gas-solid reaction through the shrinking core diffusion model (SCM). It is shown that the maximum conversion of CuCl2 is limited by the reactant velocity, reaction temperature, steam partial pressure and particle size. Results of the lab-scale experimental hydrolysis unit are presented and discussed.

A novel solar and geothermal-based trigeneration system for electricity generation, hydrogen production and cooling

In this study, a novel renewable energy based trigeneration system is developed based on the utilization of solar and geothermal resources in a combined manner. The present system includes the following useful outputs, namely electricity, hydrogen and cooling. A flash-steam geothermal power plant is used for producing electricity. The CuCl cycle is used for hydrogen production and an additional heat from the CuCl cycle is used in the absorption chiller for cooling. The energy efficiency of the trigeneration system is evaluated to be 19.6% while the exergy efficiency is found to be 19.1%. Furthermore, the CuCl hydrogen production cycle is determined to have an energy efficiency of 35.3% and an exergy efficiency of 35.9%. In addition, the energetic coefficient of performance of the absorption cooling system is evaluated as 0.54 and the exergetic coefficient of performance is 0.32. Moreover, several parametric studies are conducted to study the effects of varying operating conditions and system parameters on system performance.

Design and Analysis of a Novel Integrated Wind-Solar-OTEC Energy System for Producing Hydrogen, Electricity, and Fresh Water

Abstract A new energy system for power, hydrogen and fresh water production is proposed. The environmentally benign ocean thermal energy conversion (OTEC), wind and solar energy resources are utilized. The hybrid thermochemical CuCl cycle is used for hydrogen production, and the reverse osmosis (RO) desalination system is incorporated for producing fresh water. The presently developed system is analyzed through thermodynamic energy and exergy approaches. The energetic efficiency of the integrated trigeneration system is determined to be 45.3%, and the exergetic efficiency is found to be 44.9%. In addition to this, the energy efficiency of the OTEC power generation cycle is 4.5% while the exergy efficiency is found to be 12.9%. Furthermore, the CuCl hydrogen production cycle is examined to have exergetic and energetic efficiencies of 36% and 35.2%, respectively. Also, numerous parametric studies are performed to analyze the system performance at different operating parameters.

Thermodynamic assessment of a lab-scale experimental copper-chlorine cycle for sustainable hydrogen production

An integrated lab-scale copper-chlorine (Cu-Cl) thermochemical cycle for hydrogen production at the University of Ontario Institute of Technology (UOIT) is presented and analyzed in this paper. In a practical operation of the Cu-Cl cycle, besides the main steps of hydrolysis, thermolysis, electrolysis and drying, the oxidized anolyte (consumed anolyte at the electrolyzer cell) needs to be recycled to be concentrated sufficiently for the electro-chemical process. Recycling of the oxidized anolyte through the separation processes is achieved by distillation of anolyte, drying unit, separation cell, pressure swing distillation and CuCl2 concentrator. This study examines the thermodynamic performance of all unit operations in the lab-scale Cu-Cl cycle. A process simulation model with Aspen Plus is used to assess the system by energy and exergy analyses. For the specific system design characteristics, the cycle is capable of producing 100 L/h of hydrogen. From the simulation results, the overall energy and exergy efficiencies of the lab-scale Cu-Cl cycle are determined to be 11.6% and 34.9%, respectively. Furthermore, after the thermolysis and hydrolysis reactors, the quench cell and CuCl2 concentrator have the highest exergy losses with thermal energy transferred through CuCl solidification and water vaporization phase-change processes at relatively high temperature. Additional results of the processes are presented and discussed.

Exergy analysis and performance evaluation of a newly developed integrated energy system for quenchable generation

This paper presents an innovative use of waste heat recovered from a cement slag for multigeneration purposes, including power, ammonia, heat, hot water and oxygen production. A novel approach of ammonia production is employed in this study. The proposed system consists of four major subsystems; copper-chlorine (Cu-Cl) cycle, cryogenic Air Separation Unit (ASU), ammonia synthesis reactor and two steam Rankine cycles. The Aspen plus 9.0 version is employed for modeling and simulation of the proposed system. A comparative study is also conducted considering the different CuCl cycle based integrated systems for multigenerational purpose with numerous energy sources. The parametric studies are carried out by varying parameters, namely flow rate, compressor and turbine discharge pressures and ammonia reactor conversion rate. The exergy analysis is comprehensively conducted for each of the system components through exergy balance equations and exergy efficiencies. The overall exergy efficiency of the designed system is found to be 36.1%. Further results are also presented and discussed.

Development of a new trigenerational integrated system for dimethyl-ether, electricity and fresh water production

A novel trigeneration integrated system is proposed and analyzed in this paper. The present system utilizes gas turbine exhaust gas for heat recovery and capturing carbon dioxide after expanding in the turbine and generating electricity. Moreover, a Cu-Cl thermochemical cycle is incorporated in the system to produce hydrogen, and a multi-effect desalination is integrated to provide fresh water to the Cu-Cl cycle and for domestic use as well. The present integrated system is modeled and simulated using the Aspen Plus software package for chemical processes and Engineering Equation Solver for the remaining subsystems. Both energy and exergy analyses are performed to study and assess the proposed system through energy and exergy efficiencies. Therefore, the overall energy and exergy efficiencies of the proposed trigeneration system are found to be 39.72% and 55.2% respectively.

A comparative evaluation of three Cu[sbnd]Cl cycles for hydrogen production

The thermochemical CuCl cycle has received greater attention by numerous researchers during the past decade as a promising hydrogen production method because of some operational advantages. The present paper analyzes three different configurations of the CuCl thermochemical cycle, namely three, four and five step ones thermodynamically. Some comparative parametric studies are conducted in order to investigate the overall energy and exergy efficiencies of the cycles considered. The Aspen plus is the software tool employed for the modeling and simulation of the cycles. The energy and exergy efficiencies of the five-step CuCl cycle are found to be 38.8% and 70.2% while the three-step CuCl cycle has an energy efficiency of 39.6% and an exergy efficiency of 68.1%, respectively. On the other hand, the four-step CuCl cycle provides the highest energy and exergy efficiencies of 41.9% and 75.7%. A parametric study is also conducted to investigate the effect of varying ambient temperature on the exergy efficiencies of all three cycles. The present study results further reveal that the cycle performance can be enhanced by improving the thermal management and reducing the exergy destructions.

Azeotropic pressure swing distillation of hydrochloric-water for hydrogen production in the Cu[sbnd]Cl cycle: Thermodynamic and design methods

A pressure swing distillation (PSD) process is designed and analyzed in this paper for the maximum boiling azeotrope separation of an HCl-water binary mixture to recycle concentrated HCl (aq) within the CuCl cycle of thermochemical hydrogen production. Aspen Plus simulation and EES software are used to evaluate the characteristics of the PSD apparatus in terms of flow streams, thermodynamic properties and compositions in the binary azeotropic mixture. A heat transfer and mass transfer analysis (with the McCabe-Thiele method) are also used to predict the height of the packed bed distillation column. Results indicate that both analyses predict the same values for the low and high pressure packing column height of 1.7 m and 2 m, respectively. Due to the component's volatility changes through the azeotropic transition at the HCl-water separation, the minimum and maximum concentration of the HCl (aq) would be at the distillate ports of low and high pressure columns, respectively. Moreover, to break the azeotropic point of HCl (aq) in the PSD system, the minimum required low pressure feed concentration at the operating line slopes of 0.2, 0.4, 0.6 and 0.8 should be 0.086, 0.092, 0.097 and 0.103, respectively. From the results, the re-boiler and condenser heat duties at the high pressure distillation column are more affected with the change in the slope of the operating line, compared to the low pressure side.

Thermodynamic model of pressure swing distillation for a high pressure process of hydrochloric/water separation and hydrogen production

Recycling of concentrated HCl within the CuCl cycle for hydrogen production is necessary to achieve lower operating costs and higher efficiency. HCl and water molecules have an attraction that leads to a maximum boiling azeotrope. Thus, HCl cannot be separated from water by using a conventional distillation column. In this paper, a novel thermodynamic model and simulations in Aspen Plus are presented for a pressure swing distillation high-pressure process to separate the HCl-water azeotropic binary mixture into a concentrated HCl stream. Furthermore, a heat transfer analysis is presented to predict the packing column height. All of the stream properties and compositions in the binary azeotropic mixture, thermodynamic analysis and steady-state simulation of a high pressure distillation column are examined with Aspen Plus. The present results indicate that the high-pressure distillation system enhances the mole fraction of HCl (aq) from 0.11 up to 0.21 and the increase of reflux ratio and feed temperature assist it to be higher. The increment of 76% and 42% for the condensation and re-boiler heat duties with the growth of reflux ratio indicate the significant impact of this parameter on the high pressure distillation column. Furthermore, at the specific system operating condition, the results from the heat transfer model suggest that the distillation column with a height of 2 m would be suitable for practical operation.

Thermolysis reactor scale-up for pilot scale Cu[sbnd]Cl hybrid hydrogen production

Alternative hydrogen production methods are being explored with the goal of finding efficient and economical process. The copper-chlorine (CuCl) cycle for hydrogen production has been the focus of the Clean Energy Research Laboratory (CERL) at the University of Ontario Institute of Technology (UOIT). The CuCl cycle has lower thermal energy requirements compared to other methods and utilizes waste heat from power plants and/or industrial processes. The cycle is comprised of the electrolysis, hydrolysis and thermolysis reaction steps. Decomposition of copper oxychloride (CuOCuCl2) occurs in the thermolysis reactor at 500–530 °C. A novel thermolysis reactor design is presented here with the purpose of scaling it up to a pilot at an industrial site. Using a dual heater configuration, simulations showed decomposition temperatures were achieved between 3.5 and 4 h with 2.0 kg of CuCl as the feedstock. With 10 kg of CuCl, the reactor would reach decomposition temperatures after 10 h of heat up. Improved start-up thermal performance was observed during experiments with solidified CuCl and a reduction of startup time.

Investigation of Dissolution of Cuprous Chloride in Aqueous Hydrochloric Acid Solution with Application to Hydrogen Production Technologies

Fossil-fuel-based methods of production, transformation and use of energy are causing environmental concerns such as ozone depletion, acid rain and climate change while depleting the earth of its resources. Sustainable alternatives for energy transformation are being sought and a hydrogen economy is a potential avenue. The thermochemical copper-chlorine (Cu-Cl) cycle for water splitting into its constituents is a promising option to produce high quantities of hydrogen. One of the steps involved in the process of hydrogen production from water using the thermochemical Cu-Cl cycle is the dissolution of cuprous chloride particles in hydrochloric acid. The purpose of this study is to propose an experimental design to examine the dissolution of cuprous chloride in an aqueous hydrochloric acid solution in order to observe the reaction time and kinetics. This data will be used to develop an empirical model that correlates quantity of cuprous chloride, concentration of hydrochloric acid, electrical conductivity, and dissolution time using analysis of variance (ANOVA). Extrapolating the data gathered from the empirical model to an industrial scale will enable dissolution time prediction based on concentration and temperature for complex multiphase reactions.