1-dimensional modelling and simulation of the calcium looping process

Calcium looping is an emerging technology for post-combustion carbon dioxide capture and storage in development. In this study, a 1-dimensional dynamical model for the calcium looping process was developed. The model was tested against a laboratory scale 30 kW test rig at INCAR-CSIC, Spain. The study concentrated on steady-state simulations of the carbonator reactor. Capture efficiency and reactor temperature profile were compared against experimental data. First results showed good agreement between the experimental observations and simulations

Modeling of the oxy-combustion calciner in the post-combustion calcium looping process

The calcium looping process is a fast-developing post-combustion CO2 capture technology in which combustion flue gases are treated in two interconnected fluidized beds. CO2 is absorbed from the flue gases with calcium oxide in the carbonator operating at 650 ºC. The resulting CaCO3 product is regenerated into CaO and CO2 in the calciner producing a pure stream of CO2. In order to produce a suitable gas stream for CO2 compression, oxy-combustion of a fuel, such as coal, is required to keep the temperature of the calciner within the optimal operation range of 880-920°C. Studies have shown that the calcium looping process CO2 capture efficiencies are between 70 % and 97 %. The calciner reactor is a critical component in the calcium looping process. The operation of the calciner determines the purity of gases entering the CO2 compression. The optimal design of the calciner will lower the expenses of the calcium looping process significantly. Achieving full calcination at the lowest possible temperature reduces the cost of oxygen and fuel consumption. In this work, a 1.7 MW pilot plant calciner was studied with two modeling approaches: 3-D calciner model and 1-D process model. The 3-D model solves fundamental balance equations for a fluidized bed reactor operating under steady-state condition by applying the control volume method. In addition to the balance equations, semiempirical models are used to describe chemical reactions, solid entrainment and heat transfer to reduce computation effort. The input values of the 3-D-model were adjusted based on the 1-D-model results, in order to model the behavior of the carbonator reactor realistically. Both models indicated that the calcination is very fast in oxy-fuel conditions when the appropriate temperature conditions are met. The 3-D model was used to study the sulfur capture mechanisms in the oxy-fired calciner. As expected, very high sulfur capture efficiency was achieved. After confirming that the 1-D model with simplified descriptions for the sorbent reactions produces similar results to the more detailed 3-D model, the 1-D model was used to simulate calcium looping process with different recirculation ratios to find an optimal area where the fuel consumption is low and the capture efficiency is sufficiently high. It was confirmed that a large fraction of the solids can be recirculated to both reactors to achieve savings in fuel and oxygen consumption before the capture efficiency is affected in the pilot unit. With low recirculation ratios the temperature difference between the reactors becomes too low for the cyclic carbonation and calcination. As a general observation, the small particle size creates high solid fluxes in the calcium looping process that should be taken into account in the design of the system

Educating IT Project Managers through Project-Based Learning: A Working-Life Perspective

This study discusses project-based learning and describes a course that is designed around these principles. The study also examines the working-life requirements of today’s IT project managers and assesses the potential of project-based learning in promoting the development of the necessary skills and knowledge for successful project management. The data were collected and combined from three different sources: Recent graduates (questionnaires, n=185) were asked to identify the most important skills they needed in their work; project managers (interviews, n=15) were asked their opinions of the contents and methods used when educating IT project managers; and students (interviews, n=58) were asked what they had learned during the project-based course. According to a comparative analysis of the three sets of data, the respondent groups were unanimous regarding two aspects of working-life requirements and learning outcomes: domain-specific knowledge and social skills. The graduates and the project managers saw these as vital in the work of IT professionals, and the students mentioned them as the most important learning outcomes. The findings suggest that project-based learning may provide students with a learning environment that prepares them well for their future working lives

Mapping Bio-CO2 and Wind Resources for Decarbonized Steel, E-Methanol and District Heat Production in the Bothnian Bay

Hydrogen is a versatile feedstock for various chemical and industrial processes, as well as an energy carrier. Dedicated hydrogen infrastructure is envisioned to conceptualize in hydrogen valleys, which link together the suppliers and consumers of hydrogen, heat, oxygen, and electricity. One potential hydrogen valley is the Bay of Bothnia, located in the northern part of the Baltic Sea between Finland and Sweden. The region is characterized as having excellent wind power potential, a strong forest cluster with numerous pulp and paper mills, and significant iron ore and steel production. The study investigates the hydrogen-related opportunities in the region, focusing on infrastructural requirements, flexibility, and co-operation of different sectors. The study found that local wind power capacity is rapidly increasing and will eventually enable the decarbonization of the steel sector in the area, along with moderate Power-to-X implementation. In such case, the heat obtained as a by-product from the electrolysis of hydrogen would greatly exceed the combined district heat demand of the major cities in the area. To completely fulfil its district heat demand, the city of Oulu was simulated to require 0.5–1.2 GW of electrolyser capacity, supported by heat pumps and optionally with heat storages

Mapping Bio-CO₂ and Wind Resources for Decarbonized Steel, E-Methanol and District Heat Production in the Bothnian Bay

Hydrogen is a versatile feedstock for various chemical and industrial processes, as well as an energy carrier. Dedicated hydrogen infrastructure is envisioned to conceptualize in hydrogen valleys, which link together the suppliers and consumers of hydrogen, heat, oxygen, and electricity. One potential hydrogen valley is the Bay of Bothnia, located in the northern part of the Baltic Sea between Finland and Sweden. The region is characterized as having excellent wind power potential, a strong forest cluster with numerous pulp and paper mills, and significant iron ore and steel production. The study investigates the hydrogen-related opportunities in the region, focusing on infrastructural requirements, flexibility, and co-operation of different sectors. The study found that local wind power capacity is rapidly increasing and will eventually enable the decarbonization of the steel sector in the area, along with moderate Power-to-X implementation. In such case, the heat obtained as a by-product from the electrolysis of hydrogen would greatly exceed the combined district heat demand of the major cities in the area. To completely fulfil its district heat demand, the city of Oulu was simulated to require 0.5–1.2 GW of electrolyser capacity, supported by heat pumps and optionally with heat storages

Overview of Fluidized Bed Reactor Modeling for Chemical Looping Combustion: Status and Research Needs

Modeling of next-generation CO2 capture technology, namely, chemical looping combustion (CLC), in bubbling and circulating fluidized bed reactors is briefly reviewed, and a summary of published mathematical reactor models is presented. The emphasis is on a macroscopic modeling approach, which, aiming at both low computing times and accuracy of results, adopts a phenomenological view and combines transport equations with semiempirical correlations to describe the relevant fluidized bed phenomena, for example, gas–solid flow behavior, reaction characteristics, and thermal effects. Important aspects to be considered in the modeling of CLC in a dual fluidized bed reactor system are highlighted, together with indications of the research needs detected among the reviewed works. So far, semiempirical reactor models have been validated based on experimental results obtained at a larger scale of CLC technology, i.e, up to 0.15 MWth for gaseous fuels (syngas and methane) and up to 1 MWth for solid fuels (mainly coal). Overall, the model predictions agree reasonably well with experiments selected for validation, despite the various model formulations and input data. The research achieved in dynamic process simulation of CLC is very limited

Process integration of chemical looping combustion with oxygen uncoupling in a biomass-fired combined heat and power plant

Bioenergy with CO 2 capture and storage (BECCS) has been introduced as a promising negative emission technology (NET) that opens up the possibility of producing power and heat with negative CO 2 emissions. By combining 1.5D reactor modelling with flowsheet simulation of a complete full-scale cogeneration plant, this study assesses the applicability and potential of an advanced CO 2 capture technology, namely chemical looping with oxygen uncoupling (CLOU), for CO 2 capture from a biomass-fired combined heat and power (CHP) plant generating electricity, district heat (DH) at 75–90 °C supply and 45 °C return temperatures, and process steam at 10 and 4.5 bar(a) pressures. Nordic wood (50% wet-basis moisture) is used as fuel. The key performance indicators of the CLOU-integrated CHP plant were quantified and compared with those of a non-CCS reference plant. Part-load operation at reduced DH loads was considered. At 100% fuel load, the CLOU plant captured 99.0% of the CO 2 from the combustion of biomass and still achieved a net efficiency of 80.1% LHV, a value very close to that of the reference plant without CO 2 capture or flue gas condensation (81.1% LHV). Depending on the fuel load, the specific negative CO 2 emissions from the CLOU plant ranged from 439 to 504 kg CO2/MWh.</p

High-Efficiency Bioenergy Carbon Capture Integrating Chemical Looping Combustion with Oxygen Uncoupling and a Large Cogeneration Plant

Bioenergy with CO2 capture and storage (BECCS) is a promising negative emission technology (NET). When using sustainably produced biomass as fuel, BECCS allows the production of power and heat with negative CO2 emissions. The main technical challenges hindering the deployment of BECCS technologies include energy penalties associated with the capture process. This work evaluates the performance of an advanced CO2 capture technology, chemical looping with oxygen uncoupling (CLOU), in conjunction with biomass-fired combined heat and power (CHP) generation. Results from a MATLAB/Simulink reactor model were incorporated in a plant and integration model developed in a commercial process simulation software to quantify the key performance indicators of the CLOU-integrated CHP plant. Both energy and exergy analysis were conducted. The results show a remarkably low efficiency penalty of 0.7% compared to a conventional reference plant, and a high carbon capture efficiency of 97%. The low efficiency penalty is due to the high moisture and hydrogen contents of the biomass, and the separation of combustion products and excess air streams in the CLOU process; these together provide an opportunity to recover a significant amount of heat by flue gas condensation at a higher temperature level than what is possible in a conventional boiler. The condensing heat recovery yields an 18 MW generator power increase (3 MW loss in net power output) for the CLOU plant; in the reference plant with conventional boiler, the same scheme could achieve an increase of 9 MW (generator) and a decrease of 8 MW (net)