Revisiting the Rist diagram for predicting operating conditions in blast furnaces with multiple injections

Background: The Rist diagram is useful for predicting changes in blast furnaces when the operating conditions are modified. In this paper, we revisit this methodology to provide a general model with additions and corrections. The reason for this is to study a new concept proposal that combines oxygen blast furnaces with Power to Gas technology. The latter produces synthetic methane by using renewable electricity and CO2 to partly replace the fossil input in the blast furnace. Carbon is thus continuously recycled in a closed loop and geological storage is avoided. Methods: The new model is validated with three data sets corresponding to (1) an air-blown blast furnace without auxiliary injections, (2) an air-blown blast furnace with pulverized coal injection and (3) an oxygen blast furnace with top gas recycling and pulverized coal injection. The error is below 8% in all cases. Results: Assuming a 280 tHM/h oxygen blast furnace that produces 1154 kgCO2/tHM, we can reduce the CO2 emissions between 6.1% and 7.4% by coupling a 150 MW Power to Gas plant. This produces 21.8 kg/tHM of synthetic methane that replaces 22.8 kg/tHM of coke or 30.2 kg/tHM of coal. The gross energy penalization of the CO2 avoidance is 27.1 MJ/kgCO2 when coke is replaced and 22.4 MJ/kgCO2 when coal is replaced. Considering the energy content of the saved fossil fuel, and the electricity no longer consumed in the air separation unit thanks to the O2 coming from the electrolyzer, the net energy penalizations are 23.1 MJ/kgCO2 and 17.9 MJ/kgCO2, respectively. Discussion: The proposed integration has energy penalizations greater than conventional amine carbon capture (typically 3.7 – 4.8 MJ/kgCO2), but in return it could reduce the economic costs thanks to diminishing the coke/coal consumption, reducing the electricity consumption in the air separation unit, and eliminating the requirement of geological storage

Limits on the integration of power to gas with blast furnace ironmaking

This article compares 16 Power to Gas integrations for blast furnace ironmaking by using 17 key performance indicators. The study includes 4 types of PtG (PtH2, PtSNG using pure CO2, PtSNG using treated BFG, and PtSNG using BFG), two types of blast furnaces (air-blown and oxygen) and two types of fossil replacement (coal or coke). The blast furnaces are modelled using the Rist diagram, validated with literature data (<2% deviation). For most cases, the decrease in total CO2 emissions is around 150–215 kgCO2/tHM per MW/(tHM/h) of electrolysis. The energy penalty (in terms of electricity consumption) was found to be mostly independent on the size of the PtG plant, but greatly dependent on the type of integration (10.1–20.6 MJ/kgCO2). If significant CO2 reductions are aimed, self-sufficiency in electricity consumption will not be achieved. In practice, the maximum PtG capacity to install is limited by the decrease in the flame temperature. In this context, the PtSNG integration consuming treated BFG, applied to OBF for coal replacement, provides the best results. Assuming a 500 tHM/h blast furnace, the PtG capacity of this concept could be as large as 490 MW and avoid up to 21% of the CO2 emissions

Postmortem Quantitative Analysis of Prion Seeding Activity in the Digestive System

Human prion diseases are neurodegenerative disorders caused by prion protein. Although infectivity was historically detected only in the central nervous system and lymphoreticular tissues of patients with sporadic Creutzfeldt-Jakob disease, recent reports suggest that the seeding activity of Creutzfeldt-Jakob disease prions accumulates in various non-neuronal organs including the liver, kidney, and skin. Therefore, we reanalyzed autopsy samples collected from patients with sporadic and genetic human prion diseases and found that seeding activity exists in almost all digestive organs. Unexpectedly, activity in the esophagus reached a level of prion seeding activity close to that in the central nervous system in some CJD patients, indicating that the safety of endoscopic examinations should be reconsidered

Rapid and Quantitative Assay of Amyloid-Seeding Activity in Human Brains Affected with Prion Diseases

The infectious agents of the transmissible spongiform encephalopathies are composed of amyloidogenic prion protein, PrPSc. Real-time quaking-induced conversion can amplify very small amounts of PrPSc seeds in tissues/body fluids of patients or animals. Using this in vitro PrP-amyloid amplification assay, we quantitated the seeding activity of affected human brains. End-point assay using serially diluted brain homogenates of sporadic Creutzfeldt-Jakob disease patients demonstrated that 50% seeding dose (SD50) is reached approximately 1010/g brain (values varies 108.79-10.63/g). A genetic case (GSS-P102L) yielded a similar level of seeding activity in an autopsy brain sample. The range of PrPSc concentrations in the samples, determined by dot-blot assay, was 0.6-5.4 μg/g brain; therefore, we estimated that 1 SD50 unit was equivalent to 0.06-0.27 fg of PrPSc. The SD50 values of the affected brains dropped more than three orders of magnitude after autoclaving at 121°C. This new method for quantitation of human prion activity provides a new way to reduce the risk of iatrogenic prion transmission

Extending the Operating Line Methodology to Consider Shaft and Preheating Injections in Blast Furnaces

In the last years, the injection of reducing gases in the shaft and preparation zone of the blast furnace has been proposed as a decarbonization option, mainly associated to oxyfuel blast furnaces and top gas recycling configurations. However, the Rist diagram, which is one of the preferred methodologies to characterize the operation of blast furnaces, is not valid to evaluate these new decarbonization options. In this article we propose a generalization of the operating line methodology to extend its applicability to scenarios of variable molar flows along the blast furnace (i.e., shaft and preheating injections) and non-continuous oxidation profiles (presence of CO2 and H2O in the injected gases). The extended operating line methodology was implemented in an Aspen Plus simulation, which provides a detailed modelling of the preparation zone, the thermal reserve zone, the lower zone and the raceways. The simulation was used to validate the generalized operating line methodology through three different data sets: (i) an air-blown blast furnace with pulverized coal injection and O2 enrichment, (ii) an oxyfuel blast furnace with shaft gas injection, and (iii) an oxyfuel blast furnace with preheating gas injection in the preparation zone. In general, the discrepancy between the reference data and the simulation results is well below 3.5%, so the extended operating line methodology is considered validated

Microfabrication of Anode Functional Layer in SOFC by 3D Printer

This work aims to increase the interface between anode and electrolyte in solid oxide fuel cells by controlling the 3D microstructure with a commercial ink-jet 3D printer. Anode and electrolyte inks suitable for use in a 3D printer were prepared by altering the viscosity and the droplet size. A porous anode structure that ensures a flow path for gases was achieved by addition of acrylic particles into the anode ink. A dense electrolyte structure that prevents leakage was created. The anode and electrolyte layers were produced as long, flat strips which were aligned in parallel to form sheets; these sheets were stacked orthogonally to complete the 3D microstructure called the ‘anode functional layer’. The anode functional layer was roughly 100 micrometers on a side with a thickness of 4 micrometers. The anode functional layer was inserted between the anode and electrolyte. The assembled solid oxide fuel cell showed high performance when tested at 600 °C with dry methane as the fuel source

Performance Evaluation of Phase Separation Process Using High-concentration AMP Promoted by MAPA for CO

Reduction of the energy penalty and cost of CO2 capture from concentrated gas streams using amine-based solutions can be achieved by minimizing the energy penalty in the solvent regeneration process. High concentration 2-Amino-2-methyl-1-propanol (AMP) solution precipitates as a carbonate when enough CO2 has been absorbed. By sending the separated carbonate to the stripper, the sensible heat of regeneration can be reduced. However, previous testing using 50 weight percent AMP solution mixed with Piperazine (PZ) with solid-liquid separation showed that the CO2 recovery rate was limited to 65% due to the lack of PZ regeneration. To improve the CO2 recovery rate, a novel solution and injection process were developed. N-Methyl-1,3-diaminopropane (MAPA) was selected as an alternative promoter based on reaction rate testing. Various tests were employed to characterize the behaviour of the AMP/MAPA solution under CO2 capture and recovery conditions. The injection point was relocated to avoid the inhibition of CO2 absorption observed when CO2 semi-lean liquid was sent to the upper portion of the absorber. The CO2 recovery rate and the precipitation quantity were simulated using a model built in Aspen Plus®. The novel solution and injection set-up were evaluated experimentally by a bench-scale apparatus