Auto Thermal Research Articles

A Thermodynamics Model for the Assessment and Optimisation of Onboard Natural Gas Reforming and Carbon Capture

The paper examines pre-combustion carbon capture technology (PreCCS) for liquefied natural gas (LNG) propelled shipping from thermodynamics and energy efficiency perspectives. Various types of LNG reformers and CCS units are considered. The steam methane reformer (SMR) was found to be 20% more energy efficient than autothermal (ATR) and methane pyrolysis (MPR) reactors. Pressure swing adsorption (PSA) had a lower energy requirement than membrane separation (MEM), cryogenic separation (CS), and amine absorption (AA) in pre-combustion carbon capture, with PSA needing 0.18 kWh/kg CO2. An integrated system combining SMR and PSA was proposed using waste heat recovery (WHR) from the engine, assuming similar efficiency for LNG and H2 operation, and cooling and liquefying of the CO2 by the LNG. The SMR-PSA system without WHR had an overall efficiency of 33.4% (defined as work at the propeller divided by the total LNG energy consumption). This was improved to 41.7% with WHR and gave a 65% CO2 emission reduction. For a higher CO2 reduction, CCS from the SMR heater could additionally be employed, giving a maximum CO2 removal rate of 86.2% with 39% overall energy efficiency. By comparison, an amine-based post-engine CCS system without reforming could reach similar CO2 removal rates but with 36.6% overall efficiency. The advantages and disadvantages and technology readiness level of PreCCS for onboard operation are discussed. This study offers evidence that pre-combustion CCS can be a serious contender for maritime propulsion decarbonization.Graphical

Pathways to sustainable methanol operations using gas-heated reforming (GHR) technologies

The global methanol industry provides a unique supply chain to a plethora of chemicals and processes while also contributing to high quotas of greenhouse gas (GHG) emissions. Hence, as the world focuses on climate change mitigation, green technologies are emerging, allowing for low carbon operations. However, the timeliness and scalability of these technologies limit the sustainable transition of the current methanol industry. Thus, to promote low carbon operations within business-as-usual methanol production, innovative technologies need to be investigated-boasting high resource and energy efficiencies. Here, we examine the effectiveness of novel gas-heated reforming (GHR) over autothermal (ATR) and steam reforming (SMR)- coupled with carbon capture and storage platforms (CCS), in promoting sustainable methanol operations. Our results highlight the GHR as the most efficient flowsheet- with 11 % overall higher energy efficiency and 17 % increase in resource efficiency over ATR and SMR processes. Furthermore, through coupled CCS and electrification, energy and resource efficiencies were improved with GHR systems- achieving 14–41 % reduced GHG emissions compared to ATR and SMR flowsheets. Lastly, considering process economics, GHR flowsheets outperform- producing minimum selling prices up to 24 % lower than the current market. Ultimately, as the world seeks to promote a sustainable transition through the deployment of low carbon energy sources, GHR systems emerge as the preferred technologies- providing both economic and environmental benefits for future low carbon methanol operations.

Modeling and simulation of steam methane reforming and methane combustion over continuous and segmented catalyst beds in autothermal reactor

In this paper, a numerical analysis of the production of hydrogen via autothermal (ATR) steam methane reforming (SMR) is presented. The combustion reaction occurs over a Pt/Al 2 O 3 catalyst, and the reforming reaction is operated using a Ni/Al 2 O 3 catalyst inside the same cylindrical channel. A novel configuration with18 catalytic-bed macro-patterns alternately mounted, referred to as SDB, is designed and compared with the catalytic dual-bed reactor (conventional configuration), referred to as CDB, at the same operating temperature and pressure conditions of 900 °C and 14 bars, respectively. The results showed that hydrogen yield was improved by 4.5% compared to the conventional configuration, while a decrease of 67 °C of the highest temperature was noticed. Meanwhile, the methane conversion was 63.73% and 65.44% for the CDB and SDB configurations, respectively. Furthermore, the length of the reactor can be decreased by 27%, keeping the same hydrogen yield at the outlet of the conventional reactor, indicating a potential reduction in hydrogen cost. • Novel configuration of ATR reactor over Ni/Al 2 O 3 and Pt/Al 2 O 3 catalysts was analyzed. • The effect of combustion and reforming catalyst configuration was investigated. • The hydrogen yield was increased up to 4.5% in the SDB compared to CDB configuration. • Possible decrease of 27% in SDB length, achieving the same hydrogen yield in CDB. • Low peak and less abrupt temperature variation compared to conventional ATR.

Development of a thermally self-sustaining kWe-class diesel reformer using hydrogen peroxide for hydrogen production in low-oxygen environments

Abstract A novel technology of a diesel reformer that uses hydrogen peroxide is developed to obtain the hydrogen required for fuel cell air-independent propulsion for underwater applications, such as submarines and unmanned underwater vehicles. Diesel fuel could be a promising hydrogen source for underwater applications due to its high hydrogen density and its globally well-equipped infrastructure. An alternative oxidant, hydrogen peroxide (H 2 O 2 ), is applied to supply not only oxygen but also the water required for diesel autothermal (ATR) reforming. The proposed reformer does not require an additional heating device to supply heat for the vaporization of diesel or oxidant due to the exothermic nature of the ATR reaction and the heat of decomposition of H 2 O 2 . The effects of H 2 O 2 on diesel reforming were confirmed based on operating the engineering-scale (kW e -class) diesel-H 2 O 2 reformer. Undecomposed H 2 O 2 caused an excessively high temperature in the mixing zone and a corrosion effect in the reformer wall. To overcome these phenomena, we introduced a catalytic H 2 O 2 decomposer to fully decompose hydrogen peroxide into steam and oxygen. From this important step, we essentially eliminate side effects from undecomposed H 2 O 2 and retain a high reforming efficiency by utilizing the heat of decomposition of H 2 O 2 .

Techno-environmental analysis of the biomass gasification and Fischer-Tropsch integrated process for the co-production of bio-fuel and power

The present study focuses on the performance analysis of a biomass-to-liquid (BTL) process for the co-production of green diesel and electricity. The BTL process consists of biomass gasification and Fischer-Tropsch (FT) synthesis, and rice straw is investigated as the biomass feedstock. The modeling of the BTL process is performed using Aspen Custom Modeler (ACM). BTL processes with different configurations, i.e., with and without a tar removal unit based on steam reforming and autothermal (ATO) reforming, are compared. The amounts of green diesel and electricity produced and the overall potential environmental impact (PEI) derived from the Waste Reduction (WAR) algorithm are used as technical and environmental performance indicators and subjected to the Analytical Hierarchy Process (AHP) analysis. The simulation results demonstrate that the BTL process with ATO reforming is the most practical configuration, and the process offering maximum internal heat recovery and minimum external utility requirements is proposed. Based on the parametric analysis of key operating parameters (i.e., gasifying temperature, FT operating temperature and pressure), the optimal operating conditions of the BTL process providing the highest AHP index are identified.

Catalytic features of Ni/Ba–Ce 0.9–Y 0.1 catalyst to produce hydrogen for PCFCs by methane reforming

Methane reforming in steam (SR), auto-thermal (ATR) and partial oxidation (POX) conditions over Ni/Ba–Ce 0.9–Y 0.1 catalyst was investigated in the temperature range 500–700 °C. Catalyst presents a satisfying activity in POX condition only. BCY carrier was not stable in the presence of CO 2 and, irrespective of reaction conditions, it reacts with CO 2 giving rise to the formation of BaCO 3 and CeO 2. The very low activity observed in SR conditions was due to the negative role exerted by water strongly absorbed on catalyst surface, limiting so the accessibility and reduction state of Ni active sites. In POX condition catalyst is active and satisfying H 2 yield can be reached by operating at T = 700 °C. A significant reduction of coke formation was observed by operating in POX at 700 °C. On the contrary, in ATR condition at the same reaction temperature huge amount of filamentous coke was observed.

Design and development of a diesel and JP-8 logistic fuel processor

The paper describes the design and performance of a breadboard prototype for a 5 kW fuel-processor for powering a solid oxide fuel cell (SOFC) stack. The system was based on a small, modular catalytic Microlith auto-thermal (ATR) reactor with the versatility of operating on diesel, Jet-A or JP-8 fuels. The reforming reactor utilized Microlith substrates and catalyst technology (patented and trademarked). These reactors have demonstrated the capability of efficiently reforming liquid and gaseous hydrocarbon fuels at exceptionally high power densities. The performance characteristics of the auto-thermal reactor (ATR) have been presented along with durability data. The fuel processor integrates fuel preparation, steam generation, sulfur removal, pumps, blowers and controls. The system design was developed via ASPEN ® Engineering Suite process simulation software and was analyzed with reference to system balance requirements. Since the fuel processor has not been integrated with a fuel cell, aspects of thermal integration with the stack have not been specifically addressed.

Concept Study on ATR and SR Fuel Processors for Liquid Hydrocarbons

Models for auxiliary power units (APU) based on-board hydrocarbon fuel processors (FP) for hydrogen production for polymer-electrolyte-membrane (PEM) fuel cells were coded in Matlab/Simulink software considering the following: (i) either an autothermal (ATR) or a steam reforming (SR) unit fed with several fuels (road distribution net fuels: gasoline, light diesel, heavy diesel, and biodiesel; reference fuels in internal combustion enginer (ICE) applications: isooctane for gasoline and cetane for diesel oils); (ii) the secondary units for the CO cleanup process (water gas shift and CO preferential oxidation reactors: WGS and CO−PROX); (iii) the auxiliary units for the balance of plant of the whole system (afterburner, heat exchangers, water recovery radiators, air compressor, and water and fuel pumps), necessary to properly operate the FP; and (iv) the PEM fuel cell. First, a study on the feasibility of the substitution during the simulations of the real liquid fuels available for automotive traction (...

Diesel fuel processor for PEM fuel cells: Two possible alternatives (ATR versus SR)

There are large efforts in exploring the on-board reforming technologies, which would avoid the actual lack of hydrogen infrastructure and related safety issues. From this view point, the present work deals with the comparison between two different 10 kW e fuel processors (FP) systems for the production of hydrogen-rich fuel gas starting from diesel oil, based respectively on autothermal (ATR) and steam-reforming (SR) process and related CO clean-up technologies; the obtained hydrogen rich gas is fed to the PEMFC stack of an auxiliary power unit (APU). Based on a series of simulations with Matlab/Simulink, the two systems were compared in terms of FP and APU efficiency, hydrogen concentration fed to the FC, water balance and process scheme complexity. Notwithstanding a slightly higher process scheme complexity and a slightly more difficult water recovery, the FP based on the SR scheme, as compared to the ATR one, shows higher efficiency and larger hydrogen concentration for the stream fed to the PEMFC anode, which represent key issues for auxiliary power generation based on FCs as compared, e.g. to alternators.