Steam Methane Reforming Plant Research Articles

A Knowledge-Driven Model to Assess Inherent Safety in Process Infrastructure

Process safety has drawn increasing attention in recent years and has been investigated from different perspectives, such as quantitative risk analysis, consequence modeling, and regulations. However, rare attempts have been made to focus on inherent safety design assessment, despite being the most cost-effective safety tactic and its vital role in sustainable development and safe operation of process infrastructure. Accordingly, the present research proposed a knowledge-driven model to assess inherent safety in process infrastructure under uncertainty. We first developed a holistic taxonomy of contributing factors into inherent safety design considering chemical, reaction, process, equipment, human factors, and organizational concerns associated with process plants. Then, we used subject matter experts, content validity ratio (CVR), and content validity index (CVI) to validate the taxonomy and data collection tools. We then employed a fuzzy inference system and the Extent Analysis (EA) method for knowledge acquisition under uncertainty. We tested the proposed model on a steam methane-reforming plant that produces hydrogen as renewable energy. The findings revealed the most contributing factors and indicators to improve the inherent safety design in the studied plant and effectively support the decision-making process to assign proper safety countermeasures.

Technical performance and environmental assessment of an ionic liquid-based CCS process for hydrogen production

Hydrogen (H2) production combined with carbon capture and storage (CCS) is anticipated to be an important technology contributing to reduce the carbon footprint of current fossil-based H2 production systems. This work addresses for the first time the techno-environmental assessment of a CCS process based on the ionic liquid [Bmim][Acetate] for H2 production by steam methane reforming (SMR) and the comparison to conventional amine-based systems. Two different SMR plants using MDEA or [Bmim][Acetate] for CO2 capture were rigorously modelled using Aspen Plus to compute material and energy needs and emissions. Literature and simulation results were then used to perform a life cycle impact assessment (LCIA) of these processes based on the ReCiPe model. Solvent synthesis, CCS process and hydrogen production stages were considered for the cradle-to-gate analysis. Results showed that although [Bmim][Acetate] is a priori more harmful to the environment than amines (in a kg-to-kg comparison), LCIAs carried out for both CCS processes showed from 5 to 17 % lower environmental impacts values for all estimated categories when using [Bmim][Acetate] due to a 9.4 % more energy-efficient performance than MDEA, which also reduced a 17.4 % the total utility cost. Indeed, if a typical amine loss rate of 1.6 kg/tCO2 is assumed, the values of the environmental impacts increase up to 14 % for the IL-based CCS plant, but still maintaining its favorable results over MDEA. As consequence, the SMR plant with the IL-based CCS system exhibited 3–20 % lower values for most of the studied impact categories. These results contribute to shed some light on evaluating the sustainability of ILs with respect to conventional solvents for CO2 capture and to guide the synthesis of new more sustainable ILs but also, they would be used to compare the environmental burdens from the synthesis and process performance of other promising ILs for CO2 capture that are not environmentally assed yet.

Comparative techno-economic and life cycle greenhouse gas assessment of ammonia production from thermal decomposition of methane and steam methane reforming technologies

This study assesses the life cycle greenhouse gas (GHG) and economic feasibility of applying thermal decomposition of methane (TDM) technology for ammonia production compared to the conventional steam methane reforming (SMR) technology. A detailed process model for each ammonia-based technology was developed to get data to perform energy, life cycle GHG emissions, and economic analyses. The results showed that the SMR plant consumes 30.3% more fuel than the TDM. The life cycle GHG emissions of TDM and SMR are 1.42 and 2.51 t CO2e/t NH3, respectively. The combustion and process emissions released to the environment and electricity emissions take a large share in the life cycle emissions of SMR and TDM, respectively. The production cost of ammonia from SMR is lower than TDM by $69/t NH3. TDM requires a higher investment because of high capital costs and the huge amount of natural gas needed as feedstock. For TDM, the sale of the oxygen product does not provide sufficient revenue to outperform SMR. However, integrating a carbon capture unit into TDM makes it economic performance better than SMR (with a carbon capture unit) when the sale of oxygen is considered. The results also showed that SMR (without carbon capture unit) is more economically attractive when the carbon price benchmark is below $99/t CO2. Above this carbon price, integrating a carbon capture unit into TDM is economically preferable.

Numerical evaluation of hydrogen production by steam reforming of natural gas

Industry-scale hydrogen is mainly produced by steam methane reforming (SMR), which uses natural gas as the feedstock and fuel and co-produces CO2. This study aims to numerically evaluate hydrogen production by SMR under various reacting conditions. Unlike the previous studies with limited scenarios, the performance of SMR is continuously evaluated in a high-dimensional input-parameter space. The SMR plant including a combustor, a reformer, and a water-gas shifter is modeled in Aspen HYSYS software. The four key parameters, including methane fraction of the feedstock, reformer pressure and temperature, and shifter temperature, are treated uncertain and 50 samples are drawn from a four-dimensional parameter space defined by their ranges. Each sample is input to HYSYS model and mass ratio of each component in product streams is obtained as the output variables. Based on the 50 pairs of input-output data, response surfaces of the outputs are developed to surrogate HYSYS models. The fast response surface models are then used to calculate global sensitivity indices and evaluate SMR processes. Results show the reformer performance is controlled by temperature rather than pressure, and a temperature higher than 900 °C can maximize the reaction rate. The water-gas shifting reaction is inhibited in the reformer but significantly enhanced in the shifter. Hydrogen is mainly produced in the reformer while the major function of the shifter is to convert CO to nontoxic CO2. Cited as: Chen, M., Al-Subhi, K., Al-Rajhi, A., Al-Maktoumi, A., Izady, A. Al-Hinai, A. Numerical evaluation of hydrogen production by steam reforming of natural gas. Advances in Geo-Energy Research, 2023, 7(3): 141-151. https://doi.org/10.46690/ager.2023.03.01

Revisiting the role of steam methane reforming with CO2 capture and storage for long-term hydrogen production

Road transport is associated with high greenhouse gas emissions due to its current dependence on fossil fuels. In this regard, the implementation of alternative fuels such as hydrogen is expected to play a key role in decarbonising the transport system. Nevertheless, attention should be paid to the suitability of hydrogen production pathways as low-carbon solutions. In this work, an energy systems optimisation model for the prospective assessment of a national hydrogen production mix was upgraded in order to unveil the potential role of grey hydrogen from steam methane reforming (SMR) and blue hydrogen from SMR with CO2 capture and storage (CCS) in satisfying the hydrogen demanded by fuel cell electric vehicles in Spain from 2020 to 2050. This was done by including CCS retrofit of SMR plants in the energy systems model, as a potential strategy within the scope of the European Hydrogen Strategy. Considering three hypothetical years for banning hydrogen from fossil-based plants without CCS (2030, 2035, and 2040), it was found that SMR could satisfy the whole demand for hydrogen for road transport in the short term (2020–2030), while being substituted by water electrolysis in the medium-to-long term (2030–2050). Furthermore, this trend was found to be associated with an appropriate prospective behaviour in terms of carbon footprint.

Exergy and network analysis of chemical sites

Chemicals production is responsible for 10% of global energy consumption and 7% of greenhouse gas emissions. Material and energy efficiency are the focus of industrial and policy decision-makers but are often pursued as separate strategies. In addition, the solutions investigated are often localised without exploring the dynamics and efficiency relationships between different areas of a chemical site. Past studies have applied network analysis to study large complex systems such as national economies. The applicability to complex systems at the scale of a chemical site are clear but unexplored so far. This paper uses an integrated energy and materials metric to study an ammonia site and a steam methane reforming (SMR) plant in detail. Exergy flow maps are constructed using Sankey diagrams to illustrate the resource (material and energy) flows around the site and the principal sources of exergy loss and destruction. Exergy efficiencies and exergy destruction values are calculated for every plant, equipment within the SMR plant and mechanism of exergy destruction. This information can guide improvement interventions. The site is then modelled using a network analysis approach to improve the understanding of the energy and material interactions within it. The SMR plant is the main source of exergy destruction with an exergy efficiency of 68% and exergy destruction of 600 GJ/h, followed by the ammonia synthesis and water gas shift (WGS) plants with 99 and 59 GJ/h respectively. Within the SMR plant, the two main burners contributed the most destruction with a total of 190 GJ/h. Combustion and heat exchange are the main exergy destruction mechanisms with 206 and 141 GJ/h respectively, a result that could guide higher-level improvement efforts. More realistic transit and fuel-product exergy efficiencies definitions are found to be consistently lower than conventional efficiency definitions, an effect most pronounced in heat exchangers. The network analysis detected communities of tightly connected plants in the ammonia site and can indicate groups where cascading effects of resource efficiency improvements could materialise. The different network metrics quantifying the importance of individual plants ranked some plants, such as the steam and ammonia synthesis plant, consistently highly. Other plants, like the tail gas stripping, ranked highly on some metrics and low on others. Further work can be undertaken to better tailor some of the network metrics for the purposes of a chemical site modelled as a network. This study’s focus is ammonia production and the SMR process, but the methodology can be applied to any industrial process, particularly chemical sites, with minimal adjustments.

Study of Different Configurations for CO2 Removal in SMR Plant for Hydrogen Production

The production of hydrogen by steam methane reforming (SMR) requires a step for purification of the product-rich stream from carbon dioxide, which, after the water gas shift reaction, is the component (other than H2) present in the highest amount. This work focuses on the evaluation of different configurations for the MDEA scrubbing system with the aim of defining a scheme that allows for energy saving. This is fundamental for this type of processes, in order to make the CCS technology being operated with low economic impacts, also in fields which are not directly related to the power production. Simulations of the CO2 removal system have been carried out in ASPEN Plus®, customized for the description of the thermodynamically non-ideal system, and the best configuration has been defined. Results show that modifications of the operating conditions and addition of units as flash vessel or splitter for the rich amine solvent can help in reducing the energy requirement.

State-of-the-art of commercial electrolyzers and on-site hydrogen generation for logistic vehicles in South Carolina

The majority of the world's hydrogen production is produced in large central Steam Methane Reforming (SMR) plants. In decentralized applications with smaller hydrogen demands such as fuel cell powered logistic vehicles (FCLVs), large electrolyzers can be a cost-competitive alternative to the H2 delivery from central SMR plants. In this study, the state-of-the-art of commercial electrolyzers has been analyzed based on 16 quotes for commercial systems with electric power inputs between 0.35 and 3.35 MW. Alkaline and PEM electrolyzers were examined regarding economies of scale, H2 cost structure and capacity utilization based on a 15-year investment in the United States. All overhead costs were taken into account to ensure the transferability to future projects. Since there is little research on the on-site hydrogen generation for FCLVs, this topic was investigated at the example of the BMW Manufacturing Co. plant in South Carolina where 350 FCLVs are in use. The results reveal that alkaline electrolyzers with capacities above 25 kg/h are particularly cost-efficient and produce H2 at 4.96–5.78 $/kg. It was also found that the capacity utilization plays only a subordinate role for large electrolyzers since three-quarter of the H2 generation costs are electricity costs and hence variable costs. Conclusively the results show, that the FCLV fleet in South Carolina could be supplied at 5.1–7.5 $/kg-H2 by electrolysis compared to 5–8 $/kg-H2 for liquid hydrogen delivered from a central SMR plant.

Process simulation and economic analysis of the Calcium Looping Process (CLP) for hydrogen and electricity production from coal and natural gas

The Calcium Looping Process (CLP) is being developed to facilitate carbon dioxide (CO2) capture during the production of hydrogen (H2) from syngas. The process integrates CO2, sulfur, and halide removal with the water–gas shift (WGS) reaction in a single-stage reactor. In the CLP, a regenerable calcium oxide (CaO) sorbent is used to chemically react with and remove CO2 and other acid gases from syngas at high temperature (i.e., 550–700°C). The removal of CO2 drives the WGS reaction forward via Le Chatelier’s principle, obviating the need for a WGS catalyst and enabling the production of high-purity H2. The spent sorbent is heated in a calciner to regenerate CaO for reuse in the process and to release a concentrated CO2 stream, which can be dried and sequestered. The regenerated sorbent is then reactivated in a hydrator, to improve its recyclability, before being reintroduced into the H2 production reactor.Techno-economic analyses were performed to evaluate the application of the CLP to a coal-to-H2 plant, a steam methane reforming (SMR) plant, and an integrated gasification-combined cycle (IGCC) plant, all including ⩾90% CO2 capture. In each case, use of the CLP resulted in a 9–12% reduction in the cost of H2 or cost of electricity when compared with the use of conventional CO2 capture and WGS technologies. The economic advantage afforded by the CLP is realized because of the large amount of high-quality heat produced in the process, which is recovered to raise steam for electricity generation. This heat arises from the combustion of supplemental fuel in the CLP calciner and from the exothermic CO2 removal, WGS, and hydration reactions, which are carried out at high temperature (i.e., ⩾500°C) in the CLP. As a result of recovering this heat, the CLP-based coal-to-H2 and SMR plants, which are designed to produce 26,000kg/h H2, necessarily co-produce 320MWe and 190MWe of net electric power, respectively. Although the CLP can reduce the cost of producing H2 from coal, the resulting cost is still about 26% greater than the cost of H2 produced from natural gas using conventional WGS and CO2 capture technologies, assuming coal and natural gas prices of $1.55/GJ and $6.21/GJ, respectively. The lowest cost of H2 with CO2 capture for these fuel prices is achieved by applying the CLP to an SMR plant.

Thermoeconomic Analysis of High-Temperature Gas-Cooled Reactors with Steam Methane Reforming for Hydrogen Production

Thermoeconomic analysis was performed for high-temperature gas-cooled reactors (HTGRs) coupled with a steam methane reforming (SMR) plant in order to estimate the hydrogen production cost. Two possible HTGRs, a modified Brayton cycle HTGR (GT-HTGR) coupled with an SMR plant and a modified steam cycle HTGR (SC-HTGR) coupled with an SMR plant, were considered in this study. In these analyses, mass and energy conservation were applied strictly to each component of the system. Also, quantitative balances of the exergy and the exergetic cost for each component and for the whole system were carefully considered. The hydrogen production cost was estimated to be about $0.825/kg [$7.25/one million Btu (MM Btu)] for the GT-HTGR-SMR system and $0.728/kg ($6.41/MM Btu) for the ST-HTGR-SRM system with a uranium fuel cost of $8.40/MW·h. The hydrogen production cost estimated in this study is considerably less than the economic target of $1.70/kg ($14.96/MM Btu), indicating that hydrogen production using HTGR with an SMR plant has great economic potential.

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.

Producing hydrogen using nuclear energy

The earliest means of separating hydrogen from water was by electrolysis using electrical energy that usually had been produced by low-efficiency thermodynamic processes. Substitution of thermal energy for electrical energy in high-temperature electrolysis gives a somewhat higher overall efficiency, but significantly complicates the process. Today, the vast majority of hydrogen is produced by steam methane reforming (SMR) followed by a water-shift reaction. A well-designed SMR plant will yield hydrogen having 75?80% of the energy of the methane used. Recent work in Japan has demonstrated the feasibility of substituting high-temperature heat from a gas-cooled nuclear reactor to replace the heat supplied in SMR by the combustion of methane. Using high-temperature heat from nuclear plants to drive thermochemical processes for producing hydrogen has been studied extensively. Bench-scale tests have been carried out in Japan demonstrating the sulphur-iodine (SI) process to produce hydrogen.