Syngas Content Research Articles

Thermodynamic analysis and optimization of the semi-closed oxy-combustion supercritical CO2 power cycle with blending hydrogen into the natural gas/syngas

The semi-closed oxy-combustion supercritical CO2 (sCO2) cycle is regarded as a promising power cycle featuring the combined advantages of high efficiency and nearly 100 % CO2 capture. Blending hydrogen into fuels has attracted significant attention in the research of gas turbine and internal combustion engine power generation as it contributes to economy-wide decarbonization and bolsters the broader energy sources, especially green hydrogen. The present work carried out the thermodynamic analysis of a semi-closed sCO2 cycle to investigate how the hydrogen content in natural gas or syngas affects the operating parameters and performance. The results show that the energy efficiency decreases with increasing hydrogen content in natural gas whereas the maximum efficiency exists for the syngas with 60 % H2. The key factor is the increasing H2O content in the flue gas caused by adding hydrogen in fuels enhances both the heat-work conversion in the turbine and the heat transfer in the regenerator. The optimal turbine inlet temperature is around 1150 °C, which is the same as the basic cycle. The optimal turbine inlet pressure for natural gas and natural gas with 40 % H2 is both 28 MPa, while the optimal turbine inlet pressure decreases with hydrogen content in syngas. For all the fuels, the optimal turbine outlet pressure becomes lower for the higher hydrogen content. The maximum efficiencies obtained for natural gas, natural gas with 40 % H2, and syngas with 60 % H2 are 56.08 %, 55.52 % and 56.15 %. Finally, it is found that the recompression cycle and the multiple combustor arrangement (reheat cycle) cannot be the effective configuration for the semi-closed oxy-combustion sCO2 power cycle. The heat from the sCO2 recompression conflicts with the compression heat of the ASU, reducing the energy efficiency by 0.27 %, 0.34 %, and 1.23 % for the three fuels, respectively. The limitation of the regenerator allowable temperature requires the reheat cycle to either reduce the turbine inlet temperature or reduce the turbine outlet pressure, decreasing the energy efficiency for natural gas by 1.83 % and 6.38 % due to the reduced turbine output power or significantly increasing compression power.

Biosolid Gasification Performance Prediction Using a Stoichiometric Thermodynamic Model.

The gasification process can recover energy from biosolids produced in wastewater treatment. This paper developed a stoichiometric thermodynamic equilibrium model for biosolid gasification based on the biosolid properties, thermodynamic database, and equilibrium constants. If the calculation result showed that the quantity of char was negative, the quantity of char was put to zero, and the simulation was carried out again. The model was first verified by woody gasification under isothermal conditions, and the influence of a given temperature on biosolid gasification was simulated. The model further investigated the effects of different feedstock types, moisture contents, equivalence ratios, and reaction extensions on the adiabatic temperature, exergy efficiency, and syngas properties under autothermal conditions. The four factors were all the main factors for adiabatic temperature. The exergy efficiency depended more on the operation conditions than on the feedstock type. The H2 concentration of the dry syngas in biosolid gasification exhibited a curve both against the given temperature under isothermal conditions and against the moisture content under autothermal conditions.

Simulations on coal water slurry gasification by molecular dynamics method with ReaxFF.

Coal water slurry (CWS) is a new type of liquid coal product with low pollution, which is mainly used in the chemical industry to produce syngas (CO + H2). It is of great significance to study the microscopic mechanism of CWS gasification reaction for improving the efficiency of coal gasification. In this paper, the method of molecular dynamics based on reaction force fields (ReaxFF-MD) is used to study the gasification process of CWS/O2 system at different temperatures. The results show that, in the range of 1600-2400 K, the macromolecular network structure of lignite is decomposed into a large number of small molecular structures and a small number of light tar free radical fragments, and the types and quantities of reaction products increased rapidly. At 2400-4000 K, the free radical fragments of light tar are further decomposed and reacted with gasification agents, but the types and quantities of reaction products have little change. At 3600 K, a full gasification reaction occurred in the system, and the content of syngas is the highest. The model was established and optimized by Materials Studio (MS) software. Based on ReaxFF-MD method, Lammps software was used to simulate the gasification process of CWS/O2 system, and the reaction force field files containing C, H, O, N, and S element were used. By calculating the activation energy of gasification reaction, the rationality of the model and calculation method was illustrated. The post-processing of the results was implemented using OVITO, ChemDraw software, and self-programmed Python scripts.

Integration of Methane Reforming and Chemical Looping Technologies for Power Generation from Waste Plastic: Technical and Economic Assessment

An imperative environmental concern is escalating due to the widespread disposal of plastic waste in oceans and landfills, adversely impacting ecosystems and marine life. In this context, sustainable methods for plastic waste utilisation were evaluated, particularly for power generation. Two case studies were developed to assess the potential utilisation of waste plastic, specifically polyethylene and polypropylene, by integrating gasification with steam methane reforming (SMR) alongside two oxygen-supplying techniques for combustion including cryogenic air separation (ASU) and chemical looping combustion (CLC) for case 1 and case 2, respectively. For this, thorough process simulations of both case studies were performed to obtain detailed material and energy balances. The techno-economic analysis was performed to assess the economic performance of the processes by estimating levelized cost of electricity (LCOE). The results indicated that case 2 is more efficient (5.4%) due to the lower utility requirement of the CLC process as compared to ASU. Consequently, case 2 generated a LCOE of USD 137/MW. It was also seen from the results that the power output is directly proportional to the methane input while the increase in gasifier temperature enhances the H2 and CO content in syngas.

Investigation on Synergism and Its Influence Parameters between Coal and Biomass during Co-Gasification Based on Aspen Plus

The co-gasification of coal and biomass offers numerous benefits, including improved gasification efficiency, reduced pollution emissions, and the utilization of renewable resources. However, there is a lack of comprehensive research on the synergistic effects of, and influence parameters on, coal–biomass co-gasification. This study employs Aspen Plus simulations to investigate the co-gasification behavior of coal and corn straw, focusing on the synergistic effects and the impact of various operating conditions. A synergistic coefficient is defined to quantify the interactions between the feedstocks. Sensitivity analyses explore the effects of gasification temperature (800–1300 °C), coal rank (lignite, bituminous, anthracite), biomass mass fraction (0–50%), oxygen-to-carbon ratio, and steam-to-carbon ratio on the synergistic coefficients of effective syngas content (CO + H2), specific oxygen consumption, specific fuel consumption, and cold gas efficiency. The results reveal an optimal biomass mass fraction of 10% for maximizing cold gas efficiency, with the syngas primarily consisting of H2 (36.8%) and CO (61.6%). Higher gasification temperatures (up to 1200 °C) improve syngas quality and process efficiency, while higher-rank coals exhibit better gasification performance compared to lignite. Optimal oxygen-to-carbon and steam-to-carbon ratios are identified for maximizing syngas yield and quality. These findings provide valuable guidance for the design and optimization of industrial coal–biomass co-gasification processes, enabling the maximization of syngas quality, process efficiency, and resource utilization.

Study on mixing performance of atmospheric entrained flow gasification burner using fine ash as feedstock

A burner structure suitable for atmospheric entrained-flow gasifiers using fine ash as feedstock was proposed. The study investigates the impact of the burner structure on the mixing characteristics through 0.75:1 (geometry reduction) single-phase airflow experiments. Additionally, numerical simulations were conducted to study of the gasification process of fine ash in a 10,000 Nm3/h atmospheric entrained flow gasifier. The results indicate that a larger residual temperature near the burner outlet was observed when the diameter of the burner's gasification agents channel was 10 mm or 15 mm, approximately 0.7–0.8. Additionally, the mixing degree of the two airflows at the burner outlet was high, and the distance required for complete mixing was short. When the diameter of the gasification agent channel was 15 mm, the mixed syngas flow velocity was appropriate. This resulted in a maximum temperature of 2500 °C, an 80 % carbon conversion rate, and an outlet effective syngas (CO + H2) concentration of 62 %.

Influence mechanisms of torrefaction on syngas production from bio-waste molten salt thermal treatment

The production of high-value syngas from bio-wastes through thermal conversion is a promising way to achieve carbon neutrality. In order to reduce the cost of the process, molten salt thermal treatment has been used for bio-wastes syngas production. Moreover, the removal of oxygen and water induced by torrefaction can effectively enhance the energy density of biomass, and the effect of these changes on the quality of syngas was widely investigated. This study proposed to torrefy bio-wastes and then produce syngas in molten NaNO3-NaNO2-KNO3 at 300 ℃. Results showed that the evaluation indices of syngas were improved, while the cold gas efficiency reached 44.02 % for beech wood torrefied at 280 ℃, and the syngas quality is equivalent to the products obtained by gasification of bio-wastes. The gas yield of the torrefied bio-wastes was increased by 8.08–45.23 % compared to the raw bio-wastes. Na+ and K+ in the molten salt catalyzed the cracking of propyl chains and ring opening of aromatic rings in lignin, resulting in a prominent enhancement in CO yield. Meanwhile, torrefaction could change the solid structure, leading to a delay in gas production, and torrefaction could also increase graphitization degree of char (C–C/C = C up to 50.72 % for SB-280), thus preventing the reaction proceeding. This study provided a new approach to enhance the content and quality of syngas from bio-wastes at low temperatures.

Study on the synergy inhibition of ultrafine water mist and metal wire mesh on the syngas explosion

Synergy inhibition of wire mesh and spray mist on syngas explosion was researched. The correspondence between the explosion parameters under success and failure conditions were analyzed, and its influence regular and inhibition mechanism were revealed. An evident difference appeared in the correspondence at different synergy results. Compared with the failure, the pressure of lower end only experienced an acceleration rise under the success condition although the propagation velocity of flame was slightly increased as it approached wire mesh. Corresponding pressure was also reduced. After passing through wire mesh, flame propagation was evidently accelerated due to the turbulence disturbance caused by wire mesh despite the strong endothermic effect of mist. The corresponding explosion reaction rate was also increased. Pressures of two ends did not appear obvious change under the success condition, but the pressure of upper end was evidently reduced compared with the failure. Due to the combined effect of wire mesh disturbance and mist heat absorption, the velocity history showed a change of increasing firstly and then decreasing as the spray time increased after passing through wire mesh. The synergy inhibition was attributed to the combined physical and chemical effects, and was related to the syngas concentration and spray amount.

Evaluation of a green methanol production system using the integration of water electrolysis and biomass gasification

For a long time, the development of green shipping has been highly valued by countries and organizations. Biomass gasification-based green methanol is seen as a long-term alternative to conventional shipping fuel to reduce greenhouse gas emissions in the maritime sector. While the operational benefits of renewable methanol as a marine fuel are well-known, its cost and environmental performance depend largely on the production method. In this study, a green methanol production system based on the integration of biomass gasification and water electrolysis is proposed and evaluated via the parametric and thermodynamic analysis methods. The water electrolysis is used to increase the hydrogen content in syngas, thereby increasing the production of methanol. The results show that as the S/C ratio increases, the mass flow rate and the calorific value of product gas, the mole flow rate of methanol decreases. The enhancement of the H2/CO ratio can increase the mole fraction of H2, thereby increasing the methanol yield. The mole flow rate of methanol dramatically increases from 925.0 kmol/h to 3725.2 kmol/h. Additionally, the mole flow rate of methanol in the proposed system is 10776.0 kmol/h, larger than the traditional system of 3603.4 kmol/h. The carbon element conversion rate of the proposed system is 94.6%, higher than the 31.5% of the traditional system. This system can significantly provide an efficient green methanol production method for the shipping sector, while also helping to find a feasible solution for the consumption of renewable energy.

Integrated neural network and aspen plus model for entrained flow gasification kinetics investigation

Entrained flow gasification is a well-established technology, however, the main obstacle in process design is complex gasification mechanism, since numerous phenomena at extreme process conditions take place simultaneously. This study is focused on integrated thermodynamic and artificial neural network approach (ANN) for entrained flow gasification kinetics investigation. Data on 102 feedstock materials composition was used in AspenPlus gasification simulation, where sensitivity analysis was performed for different equivalence ratio (0.1-0.7) and gasification temperature (1200-1500?C) values. For analyzed materials, optimal equivalence ratio range exist (usually 0.3-0.4), maximizing gasification efficiency. Obtained results were used in ANN development for each output variable (syngas composition, efficiency, heating value and carbon conversion). Matlab algorithm was used for determination of optimal number of neurons (1-20 range) in each ANN. High R2 values (>0.99) for all models suggested good agreement between simulated and predicted values. Genetic algorithm-based optimization studies for maximization of hydrogen content and cold gas efficiency result in mean ER value of 0.35 and 0.41, respectively, at temperature of 1200?C. Yoon interpretation method was used for quantifying relative impacts of each input variable on syngas content and gasification efficiency. Proposed approach represents a powerful tool which can facilitate investigation of entrained flow gasification and process design.

Thermodynamic analysis of a plasma co-gasification process for hydrogen production using sludge and food waste as mixed raw materials

To solve the problem that sludge and food waste are easy to putrefy and cause secondary pollution to air and groundwater, this work proposes a plasma co-gasification for hydrogen model of sludge and food waste and uses experimental data to verify the model. Based on the simulation results, the effects of plasma gasification temperature and steam to feedstock ratio on the performance of sludge + food waste plasma co-gasification process are discussed by sensitivity analysis. The syngas component characteristics, energy upgrade factor and thermodynamic efficiency of each unit of the two processes are studied. The results show that the hydrogen production capacity of co-gasification process of municipal sludge + food waste is 57.43 % higher than that of the industrial sludge + food waste. The H element content in the raw material is a key factor affecting the hydrogen production in the plasma co-gasification process, while the relative balance of H2 and CO content in crude syngas is conducive to improving the hydrogen production capacity in the entire process. The exergy efficiencies of the two processes are 56.57 % and 56.77 % respectively. This study can provide a new concept for both resource utilization and harmlessness of sludge and food waste treatment.

CO2 enhanced continuous microwave pyrolysis of low-density polyethylene to produce high-quality products: Energy recovery balance and intrinsic mechanism exploration

The utilization of microwave pyrolysis technology and CO2 dry reforming to recover high-quality products from waste plastics has become a research hotspot. In this work, light fuels were recovered by CO2-enhanced continuous microwave pyrolysis (CMP) of low-density polyethylene (LDPE). The balanced relationship between CO2 utilization and energy recovery was investigated, and the intrinsic pyrolysis mechanism was analyzed. Increasing the pyrolysis temperatures and CO2 concentrations helped to increase the pyrolysis gas yield and the syngas content, which were 96.44 wt% and 65.61 vol%, respectively. CO2 enhanced the CMP degree of LDPE and reacted with intermediates to form oxygen-containing intermediates to produce high-quality products and release CO, thereby regulating the syngas content and H2/CO ratio (0.62–3.99). Although an increase in CO2 concentration enhanced CO2 utilization efficiency, it reduced energy recovery efficiency by increasing energy consumption. The efficiencies of CO2 utilization and energy recovery could reach 81.69% and 75.29% at pyrolysis conditions of 650 °C-75 vol% CO2 and 650 °C-25 vol% CO2, respectively. Appropriate CO2 concentration (25 vol%) was the key to synergistically improving product quality, resource utilization, and energy recovery. This work evaluated the potential of CO2-enhanced CMP to produce high-quality products and provided novel insights for improving the resource utilization efficiency of waste plastics and CO2.

Syngas production in a downdraft gasifier using food waste: a case study

ABSTRACT The energy production potential of some common food waste, including cooked rice, “eba,” orange, yam, and potato peels, has been studied through thermodynamic modeling and simulation. The key gasification processes were modeled individually in ASPEN PLUS. The component properties were calculated with Peng-Robinson’s equation of state. The effect of the equivalence ratio (ER), steam-to-biomass ratio (STBR), and gasifier operating temperature on the composition, cold gas efficiency (CGE), and higher heating value (HHV) of the syngas was studied. Results revealed that the production of H2 and CO2 reduces with the increase in ER and increases with STBR. The molar fraction of CO is inversely proportional to that of CO2. Increasing ER causes an increase in oxidizer within the gasifier and a corresponding increase in the molar fraction of N2. Reduction in STBR reduces both the N2 content and heating value of syngas. Syngas from both feedstocks has heating values ranging from 18.48 to 11.04 MJ/kg, with food waste yielding higher HHV than hardwood. The CGE for hardwood ranges from 55.6% to 74.95%, while for food waste, it ranges from 49.3% to 57%. This study demonstrates the production of high-quality syngas from locally sourced food waste.

Thermodynamic performance comparison of a SOFC system integrated with steam reforming and dry reforming by utilizing different fuels

This work investigates the thermodynamic analysis of syngas production from several fuels by steam reforming or dry reforming for SOFC-integrated systems. Four commonly used fuels are considered: methanol and glycerol (alcohols), methane, and diesel (hydrocarbons). The integrated system is modeled on Aspen Plus using the Gibbs free energy minimization method and a generic electrochemical model to assess the effect of critical parameters on system performance. The results indicate a carbon-free zone within the reformer, and alcohols provide better resistance to carbon deposition than hydrocarbon fuels. Elevating the reforming temperature and STCR/CTCR increases the hydrogen concentration of syngas while also avoiding carbon deposits in the external reformer. Increasing the temperature and fuel utilization factor of SOFCs has been found to enhance electrical efficiency but at the expense of diminished thermal and total efficiency. For given operating conditions, the electrical efficiencies of methanol, glycerol, methane, and diesel are observed to be 47%, 46%, 51%, and 49% for the SR-SOFC system, and 45%, 42%, 42%, and 33% for the DR-SOFC system, respectively. The methane-SR-SOFC and methanol-DR-SOFC systems have the highest electrical efficiency, while diesel is unsuitable for the DR-SOFC system. This work can advise engineers to select the appropriate fuel types and reform technologies for SOFC-integrated systems.

Air-Blown Biomass Gasification Process Intensification for Green Hydrogen Production: Modeling and Simulation in Aspen Plus

Hydrogen produced sustainably has the potential to be an important energy source in the short term. Biomass gasification is one of the fastest-growing technologies to produce green hydrogen. In this work, an air-blown gasification model was developed in Aspen Plus®, integrating a water–gas shift (WGS) reactor to study green hydrogen production. A sensitivity analysis was performed based on two approaches with the objective of optimizing the WGS reaction. The gasifier is optimized for carbon monoxide production (Case A) or hydrogen production (Case B). A CO2 recycling stream is approached as another intensification process. Results suggested that the Case B approach is more favorable for green hydrogen production, allowing for a 52.5% molar fraction. The introduction of CO2 as an additional gasifying agent showed a negative effect on the H2 molar fraction. A general conclusion can be drawn that the combination of a WGS reactor with an air-blown biomass gasification process allows for attaining 52.5% hydrogen content in syngas with lower steam flow rates than a pure steam gasification process. These results are relevant for the hydrogen economy because they represent reference data for further studies towards the implementation of biomass gasification projects for green hydrogen production.

Experimental studies on CO2-thermal plasma gasification of refused derived fuel feedstock for clean syngas production

In the cycle of waste generation and management, the recovery of energy from solid wastes through highly efficient and low pollutant technology is a promising way. Hence, the current study focuses on clean syngas production via CO2-plasma gasification of a solid waste termed as refused derived fuel (RDF). The performance of feed rate, gas flow rate and plasma power on the syngas concentration, yield and cold gas efficiency (CGE) is studied. The high-quality syngas with H2 (42.6 vol%), CO (44.06 vol%) content possessing a lower heating value of 13.95 MJ/m3 is obtained with a cold gas efficiency (CGE) of 39.60 % by utilizing a maximal power of plasma torch (1.6 kW). However, with optimum process parameters, a higher CGE of 49.90 % is obtained. The obtained liquid oil with LHV of 30.59 MJ/kg could be used in boilers, diesel engines, etc., while the residue containing TiO2, CaAl4O7, MgCO3, etc. has healthcare, paints, cement industry, etc. applications upon further enrichment. The reaction mechanism of RDF to syngas and other products under plasma conditions is also proposed. Finally, an empirical correlation is developed to predict the composition of each component, calorific value and CGE of the syngas with the experimental results using SPSS software.

Exploration of characteristics and synthesis gas suitability for heat generation of coffee biomass pellets produced by single and co-pelletization.

Production of coffee beans generates various types of biomass that can be applied as bioenergy for drying and roasting the beans. Thus, the aims of this study were to explore the characteristics of coffee biomass pellets (CBPs) produced from coffee cherry pulp (CCP), coffee parchment (CPM), and expired green coffee beans (ECB) by single and co-pelletization. The CBPs were then used to produce the synthesis gas in a downdraft gasifier, and the syngas properties were investigated for further heat applications. The results showed that single and co-pelletization of CCP and CPM performed well. The CBPs had good physiochemical properties in shape, size, and atomic ratios. The higher heating value and energy density of CBPs were 19.25-24.29MJ/kg and 12.09-14.87 GJ/m3. The ash from CBPs was rich in K2O, CaO and MgO oxides, and the CPM ash had the lowest initial deformation temperature at 1136°C. The ash samples from CBPs also had different slagging and fouling indexes. The syngas from CBPs mainly contained H2 (6.85-9.30%), CO (12.15-18.85%), and CO2 (10.85-13.75%). The heating value and tar concentration of syngas from CBPs were 3.24-4.32MJ/m3 and 21.75-30.92g/m3. The main chemical compounds in tar were styrene, phenol, caffeine, and pyrrole according to GC-MS. These results indicate that CCP and CPM have potential for pelletization and gasification to generate heat needed for coffee bean processing.

The Effects of Raw Material Ratio and Calorific Value on Gasification Rate from Co-Gasification of Coal and Biomass (Bagasse)

To reduce greenhouse gas pollution by 29% in 2030 and actively fight climate change, Indonesia uses biomass as an alternative energy which can be combined with coal. Bagasse is a relatively abundant biomass that has not been effectively utilized. Bagasse can be used as a more effective alternative energy source if it is processed with co-gasification, which is the conversion of solid fuel into gas from two different fuel materials at the same time to produce syngas. The characteristics of biomass and coal co-gasification are closely linked to reactor type and gasification parameters such as temperature, gasifying agent, and mass ratio. The composition of the produced syngas changes depending on the calorific value of the coal used and the raw material ratio. The amount of syngas produced rises in direct proportion to the amount of biomass, and the quantity of air supplied causes complete combustion, so the syngas content decreases. The impact of the calorific value of the coal used, as well as variations in the ratio of the composition of coal and bagasse, on the supply of oxygen in downdraft type gasification equipment is investigated in this study. Bagasse characteristics identified by proximate and ultimate analysis indicate that this biomass can be used as an alternative source of renewable energy. The co-gasification process with 100% coal raw material has the highest temperature and the longest time; the co-gasification process with 100% sugarcane bagasse raw material has the lowest temperature and the shortest time; and the duration of the flame produced in syngas ranges from 5-6 minutes. The 25% bagasse and 75% coal ratio provided the fastest high temperature in this testing, making it more efficient. The calorific value of coal and biomass determines combustion efficiency, with 5300 cal/gr coal producing heat that lasts longer than 3800 cal/gr and 4500 cal/gr.

Thermodynamic modeling and performance analysis on co-gasification of Chlorella vulgaris and petrochemical industrial sludge via Aspen plus combining with response surface methodology

The co-gasification process of Chlorella vulgaris (CV) and petrochemical industrial sludge (IS) was uncoupled and simulated by Aspen Plus. The co-gasification process was considered into drying, pyrolysis, partial oxidation, as well as reduction and reforming. Simulation results showed that, the interactions between IS and CV were found for the differences in CHO, and affected by the IS ratio and gasification temperature. Increasing the temperature could improve the CO content, and get optimal H2 at 700 °C, while decrease CO2 and CH4 contents, thus lead to a higher LHV (lower heating value) of syngas, CGE (cold gas efficiency), and syngas content, CO selection. The higher S/IS-CV (steam to IS-CV blends ratio) value favored H2 production but reduce CO content and CGE. As air equivalent ratio (ER) increased, the H2 content constantly reduced, while CO varied slightly when the ER was lower than 0.10. After the ER value was higher than 0.10, CO reduced and thereby decreasing co-gasification performance. When the drying degree of feedstock increased, the CO content continuously increased, leading to better co-gasification performances. The RSM results showed that the significance factors in the interactions are ER and drying degree, S/IS-CV and ER, gasification temperature and ER, and gasification temperature and ER, respectively for CGE, LHV, Csyngas, and SelCO.

Roles of radiation reabsorption on flame speed and NO emission during ammonia combustion with syngas blending at elevated pressures

The radiative properties of NH3 and CO have considerable effects on ammonia-syngas flames, which has not been investigated at present. Radiation reabsorption effects on flame speed and NO production of one-dimensional premixed ammonia/syngas/air laminar flames were studied, encompassing a wide syngas content range and elevated pressures up to 25 atm. The improvement of flame speeds by radiation reabsorption reached 25.9% and decreased with rising syngas content, controlled by the direct-radiation effect and the reaction NH2 + NO = N2H + OH (R287). The relative enhancement of NO production decreased from 19.7% to 1.1% with increasing syngas content, affected by N + OH = NO + H (R273). The radiation reabsorption increased the flame speed by 25% at 18 atm. The coupling impact of high pressure and radiation reabsorption on flame speed was dominated by NH + NO = N2O + H (R279) and R287 via NH and OH radicals, respectively.