Carbon-hydrogen Ratio Research Articles

Soot evolution in ethylene combustion catalyzed by electric field: experimental and ReaxFF molecular dynamics studies

In this study, an electric field (E-field) was used to regulate the formation and oxidation of soot in combustion. In the procedure, an E-field is applied to the ethylene non-premixed flame, the flame is stretched horizontally and the flame height is reduced. By comparing the partially premixed flame to eliminate the effect of the E-field on the increase of combustion temperature caused by premixing, transmission electron microscope (TEM) detection revealed that the soot particles were more dispersed in the action of E-field, the “core-shell” structure of soot disappeared, and the markedly improved oxidation rate of soot in the flame. The evolution process of soot in ethylene combustion was studied by reactive molecular dynamics. The 9 ns simulation was performed at E-field strengths of 0, 0.001, and 0.1 V/Å by three successive modelings. The results showed that the E-field reduced the growth of the largest molecule in the system and increased the coagulation time of the initial soot particles. With increasing E-field strength, the “core-shell” structure of soot gradually broke. An increased hydrogen-carbon ratio and decreased number of six-membered rings are the internal factors for the more scattered structure of soot, which allows the soot to be more easily oxidized.

Direct oxidative coupling of methane into ethylene in a catalyst-enhanced planar solid oxide fuel cell stack reactor

This study presents an efficient method to convert methane into valuable olefins using a Solid Oxide Fuel Cell (SOFC) membrane reactor. Methane, abundant in natural and shale gas, serves as a sustainable feedstock due to its favorable carbon-hydrogen ratio. The SOFC membrane reactor eliminates costly air separation units and safety risks associated with explosive methane-oxygen mixtures. A planar SOFC stack achieves over 30 % methane conversion, 40 % ethylene selectivity, and power generation capabilities. Optimization with mixed-conducting ceramics enhances electrical performance without compromising catalytic activity. The stack's scalability is demonstrated, with the 5-cell configuration surpassing the 2-cell setup. This innovative approach offers a sustainable solution to methane waste, producing high-value chemicals while reducing environmental impact.

Experimental investigation for temperature and emissivity by flame emission spectrum in a cavity of rocket based combined cycle combustor chamber

Flame temperature and spectral emissivity were the important parameters characterizing the sufficient degree of fuel combustion and the particle radiative characteristics in the Rocket Based Combined Cycle (RBCC) combustor. To investigate the combustion characteristics of the complex supersonic flame in the RBCC combustor, a new radiation thermometry combined with Levenberg-Marquardt (LM) algorithm and the least squares method was proposed to measure the temperature, emissivity and spectral radiative properties based on the flame emission spectrum. In-situ measurements of the flame temperature, emissivity and spectral radiative properties were carried out in the RBCC direct-connected test bench with laser-induced plasma combustion enhancement (LIPCE) and without LIPCE. The flame average temperatures at fuel global equivalence ratio (α) of 1.0b and 0.6 with LIPCE were 4.51% and 2.08% higher than those without LIPCE. The flame combustion oscillation of kerosene tended to be stable in the recirculation zone of cavity with the thermal and chemical effects of laser induced plasma. The differences of flame temperature at α = 1.0b and 0.6 were 503 K and 523 K with LIPCE, which were 20.07% and 42.64% lower than those without LIPCE. The flame emissivity with methane assisted ignition was 80.46% lower than that without methane assisted ignition, due to the carbon-hydrogen ratio of kerosene was higher than that of methane. The spectral emissivities at 600 nm with LIPCE were 1.25%, 22.2%, and 4.22% lower than those without LIPCE at α = 1.0a (with methane assisted ignition), 1.0b (without methane assisted ignition) and 0.6. The effect of concentration in the emissivity was removed by normalization to analyze the flame radiative properties in the RBCC combustor chamber. The maximum differences of flame normalized emissivity were 50.91% without LIPCE and 27.53% with LIPCE. The flame radiative properties were stabilized under the thermal and chemical effects of laser induced plasma at α = 0.6.

Ultimate Analysis of Water Chestnut (Trapa natans Var. bispinosa Roxb) Affected by Various Inorganic and Organic Sources

The present investigation aimed to know the impact of various organic and inorganic fertilizers on the Ultimate parameters of water chestnuts. The ultimate analysis included the percentage of nitrogen, hydrogen, carbon, sulfur, protein, carbon-hydrogen ratio, and carbon–nitrogen ratio from kernels, fruit peel, and chestnut plants. For kernels, T4 (Nano-Urea @ 4.0%) had the greatest percentages of Nitrogen (1.99), Carbon (41.95), Hydrogen (6.767), Sulphur (0.244), Carbon-Hydrogen ratio (6.20), and Protein (12.44). T2 (½ RDF Nutrient + DAP) had the highest Carbon-Nitrogen ratio (23.26). The largest percentages of nitrogen (2.51), sulfur (0.342), and protein (15.69) were found in T5 (Jivamrut @ 10%) for peel estimate, whereas T1 (Control) exhibited the highest ratios of carbon to nitrogen (21.27) and carbon-hydrogen (7.22). T2 (½ RDF -Urea + DAP) had the highest proportion of hydrogen (5.53), whereas T6 (RDF) had the highest percentage of carbon (39.33). In contrast, T6 (RDF) had the largest percentages of carbon (36.75), hydrogen (5.29), and carbon-hydrogen ratio (19.02) for the chestnut plant. T5 (Jivamrut @ 10%) had the highest percentages of nitrogen (2.68), sulfur (0.588), carbon-hydrogen ratio (6.93), and protein (16.75).

Substances and energy metabolism of green Hydrogen-Assisted/Coal-Methanol-Olefin-Polyolefin system using ecological network methodology

It is crucial to comprehend the complex interconnections among units in coal chemical industry for its lower carbon and efficient transformation. This understanding can help identify priority nodes for optimization in the pursuit of lower carbon emissions and improved efficiency. Ecological network analysis method is employed to study the substances and energy metabolism in the coal chemical industry treating it as a superorganism comprising numerous intricate metabolic processes. Network utility analysis and network control analysis are conducted to evaluate the substances and energy metabolism of the coal-methanol-olefin-polyolefin (CMOP) system and green hydrogen-assisted CMOP (GH-CMOP) system, applying an innovative perspective and methodology. Key units for significant improvements in C/H/O and energy metabolism are disclosed. The GH-CMOP system shows better cascade utilization of C/H/O and energy, but hydrogen-carbon ratio adjustment has less impact on the overall metabolic utility relationships. Therefore, both systems need process route modifications to enhance substances and energy use.

Thermal extraction of coal and derivatives to prepare hot-pressed coal briquette for COREX application

In this study, the thermal extraction of various coal and derivatives by N-methylpyrrolidone was systematically compared and the extract was used as binder to prepare hot-pressed coal briquettes (HPCBs). The results demonstrate the effectiveness of thermal extraction in converting coal to HyperCoal, and the conversion yields varied from 12 to 71%. While the extraction tends to have a linear relationship with hydrogen-carbon ratio of raw coals, this relationship was not directly observed for derivatives due to inherent changes occurring during production. Proximate analysis of the extract reveals a reduction in ash content to below 1% while an increase in volatile matter by more than 8%. XPS and FTIR spectra demonstrate the high efficiency of thermal extraction in extracting hydrocarbons, but poor for compounds such as alcohols, phenols, ethers, and carboxylic acids. The extracts, rich in hydrocarbons, exhibited excellent thermoplasticity, making them suitable binders for HPCBs preparation. Among the extracts, coal derivatives exhibited higher compressive strength compared to coals. Consequently, the extract derived from direct coal liquefaction residue with the highest compressive strength was selected for preparing HPCB. Furthermore, we investigated the application characteristics of the HPCB and identified its great potential for use in COREX melting-reduction ironmaking. The preparation of HPCB is vital for expanding the utilization of bituminous coals while reducing dependence on lump coal and coking coal resources.

Environmental and energy valuation of waste-derived Cymbopogon Martinii Methyl Ester combined with multi-walled carbon (MWCNTs) additives in hydrogen-enriched dual fuel engine

This study uses a Capparis Spinosa Methyl Ester or Cymbopogon Martinii Methyl Ester (CMME25) and hydrogen dual fuel engine using multi-walled multi-additive nanotubes (MWCNT). In this experiment, a single-cylinder diesel engine was used. Through the intake manifold, hydrogen is introduced at predetermined flow rates of 5 and 10 lpm. The enriched hydrogen MWCNT of 50 and 100 ppm is combined with the CMME25 fuel. Results from the first round of experiments showed that combustion characteristics and performance were improved by hydrogen enrichment. The addition of hydrogen in the CMME25 fuel blend exhibited better performance (BTE (2.52% higher at 5 lpm and 4.52% higher at 10 lpm), BSFC (1.8% lower at 5 lpm and 2.2% lower at 10 lpm), and increased combustion parameters with lower ignition delay and combustion duration and lower emission gases (CO (8.3% at 5 lpm and 13.4% at 10 lpm), HC (7.2% at 5 lpm and 13.1% at 10 lpm), smoke (4.27% at 5 lpm and 9.06% at 10 lpm)) except NOx emission (4.82% at 5 lpm and 8.16% at 10 lpm) when compared with CMME25 without hydrogen addition. The second phase discussed the effect of multi-walled nanotubes (MWCNTs) blended with CMME25 fuel enriched with hydrogen of 10 lpm. The addition of multi-walled nanotubes in the CMME25 fuel blend revealed that higher BTE and lower BSFC were observed. MWCNT nanoparticles operate as catalysts to accelerate combustion. Minimising ignition delay and HRR advances peak HRR. Hydrogen increased the hydrogen-carbon ratio, improved air/fuel mixing, and shortened combustion, reducing CO emissions. MWCNTs decreased HC emissions by catalysing fuel oxidation and combustion. NOx emission was 6.3 and 12.8% lower for MWCNT 50 and 100 ppm, respectively. Smoke emissions decreased by 8.1 and 14.22% for MWCNT 50 and 100 ppm. Nanoparticles improved fuel droplet evaporation, thermal conductivity, and smoke emission.

Development of multi-component surrogate fuel for marine diesel considering fuel physical-chemical properties

Herein, as an alternative to heavy fuel oil (HFO), a multi-component surrogate fuel was developed, consisting n-tetradecane (6.36 %), n-hexadecane (4.25 %), i-hexadecane (20 %), n-eicosane (15 %), decalin (17 %), toluene (4.45 %), naphthalene (13 %), and phenanthrene (19.94 %). The proportions of the components of the surrogate fuel were determined by studying the chemical and physical characteristics of HFO. The surrogate fuel was optimized by matching the cetane number (CN), density at 20 °C, lower heating value (LHV), and hydrogen-carbon (H/C) ratio. The developed skeletal surrogate mechanism constituted 128 species and 375 reactions. It was extensively validated using various fundamental experiments based on its single components and HFO performance under relevant engine conditions. The predicted ignition delay time in shock tubes and the concentrations of primary species in jet stirred reactors and flow reactors were in good agreement with the previously measured values. The predicted laminar flame speed in counterflow configuration was close to the experimental data. The flame spray and combustion characteristics were found to be well produced by the proposed mechanism in a fuel ignition analyzer and a two-stroke marine diesel engine. The proposed skeletal mechanism exhibited reliable overall performance for combustion behavior, indicating that it can be used for modeling HFO in realistic engine applications.

Obtaining and characterizing biochar from Eichhornia crassipes using a solar pyrolysis reactor prototype

[Introduction]: Latin America has extensive wetland areas of international importance, since these wetlands preserve wildlife, acting as a source and purifier of water; protecting us from floods, droughts, and other environmental disasters. However, these wetlands are threatened by eutrophication and aquatic weeds, such as the water lily in La Presa, La Vega, Jalisco, Mexico. [Objective]: The present investigation provides an alternative for the sustainable management of the water lily (Eichhornia crassipes) by obtaining biochar and its evaluation. [Methodology]: A functional prototype of a solar pyrolysis reactor was developed, running 36 tests to pyrolyze water lily samples with 17-23% humidity, applying a 5 in Hg vacuum at different temperatures (170, 200 and 230 ºC) and residence times (120, 150, 180 and 210 min); finding the best yield of biochar by the response surface method. [Results]: The optimal conditions in the reactor were found at 170 ºC, with a residence time of 171.8 min. The biochar presented a calorific value of 17.56 MJ/kg, 20.11 % by weight of fixed carbon and 6.89 C/H (carbon-hydrogen) ratio. [Conclusions]: This proposal provides evidence for a new solar pyrolytic reactor that processes water lily to produce high calorific biochar or to fix carbon, which could be a solution to one of the effects of eutrophication.

Prediction model for methanation reaction conditions based on a state transition simulated annealing algorithm optimized extreme learning machine

Methanation is the core process of synthetic natural gas, the performance of the entire reaction system depends on precise values of the reaction condition parameters. Accurate predictions of the CO conversion rate of the methanation reaction can eliminate time-consuming and complex steps in experiments and speed up the discovery of the best reaction conditions. However, the methanation reaction is an uncertain, highly complex, and highly nonlinear process. Thus, this paper proposes a machine learning prediction model for the methanation reaction to facilitate the subsequent search for optimal reaction conditions. The reaction temperature, pressure, hydrogen–carbon ratio, water vapor content, CO2 content, and space velocity were selected as the condition variables. The CO conversion rate was the optimization objective. An extreme learning machine (ELM) was selected as a prediction model. Because the input weights and bias matrices of the ELM are randomly generated, an ELM based on a state transition simulated annealing (STASA-ELM) algorithm is proposed. The STASA algorithm was used to optimize the ELM to improve the accuracy and stability of the model. Five additional sets of experimental data were designed for the experiment, and the error between the experimental and predicted values was small. Thus, the STASA-ELM algorithm can accurately predict the conversion of CO for different values of reaction conditions.

Multi-spectroscopic characterization of bitumen and its polarity-based fractions

• Insights on H/C-ratio, aromatic systems and average molecular sizes are obtained. • NMR reveals varying chain lengths of aliphatic substituents throughout the fractions. • Characteristic NMR shifts in the resins suggest presence of some esters or amides. • 31 P NMR after derivatization, shows minor amounts of alcohols and carboxylic acids. Bitumen contains a complex mixture of molecules, ranging from simple linear alkanes to complex polyaromatic systems. Used in road construction, those structures are permanently influenced by atmospheric processes, which result in oxidation, degradation, loss of volatiles and structural rearrangements. In order to understand those molecular changes, a profound description of the unaltered system is needed. In this study, structural and chemical peculiarities of bitumen and its polarity-based fractions were analysed using nuclear magnetic resonance (NMR) techniques in combination with infrared/fluorescence spectroscopy and elemental analysis. The bitumen sample was separated into saturates, aromatics, resins and asphaltenes. Elemental analysis provided insights into variations of heteroatom content and hydrogen-carbon ratio among the fractions. Fluorescence spectroscopy showed an increase in the aromatic condensation degree with rising polarity. The combination of heteronuclear single quantum coherence (HSQC) and elemental analysis facilitated the assessment of length and branching extent of aliphatic side chains, throughout the fractions. Another 2D NMR technique, heteronuclear multiple bond coherence (HMBC) found evidence for minor contributions of carboxylic esters or amides within the resins. Hydroxyl and amino groups were analysed by 31 P NMR after derivatization, revealing minor amounts of alcohols, amides and carboxylic acids in the most polar fractions. Additionally, diffusion ordered spectroscopy was carried out to obtain estimations on average molecular sizes and weights. Applying in-depth NMR analysis to bitumen and combining it with complementary analytical techniques, this study provides a unique basis for future ageing studies and demonstrates how multi-spectroscopy can give new insights into bitumen structure and chemistry.

Athabasca Toe-to-Heel Air Injection Pilot: Evaluation of the Spontaneous Ignition Based on Apparent Atomic Hydrogen-Carbon Ratio Variation

Summary An in-depth analysis was performed to determine the ignition delay via the enhanced spontaneous ignition (ESI) method on three well pairs (each pair constituted by one vertical injector and one horizontal producer) belonging to the Toe-To-Heel Air Injection (THAI) pilot in Athabasca. ESI consisted of preheating of the surroundings of injection wells by injecting a steam slug for 3 to 4 months just before starting air injection. At first, the ignition delay had been determined based on both the oil production and on the bottomhole temperatures (BHTs) recorded in the observation wells as well as at the toe of the horizontal producer. For the purposes of this paper, a more rigorous evaluation was carried out based on the variation in time of the apparent atomic hydrogen-carbon ratio (AAHCR) calculated from detailed gas analyses for a long period of time. AAHCR is a very strong synthetic parameter giving a direct indication of the peak temperature value before, during, and after the in-situ combustion (ISC) front is generated. Therefore, it provides complete information on the occurrence of high-temperature oxidation and low-temperature oxidation (LTO) reactions. Using the variation of the AAHCR, it was found that the ignition time was shorter than those determined by the previously mentioned methods. In the case of first well pair, ignition took 3 weeks as compared to the 1 month determined by the previous methods. The second well pair ignited in 1 month as compared to the previously calculated 2 months, and for the third well pair, ignition time was approximately 2 months in both cases. As an additional and complementary approach, estimation of the ignition time was also based on the variation of individual components of the produced gas. This allowed for the discovery of a new method for ignition time determination. This was possible in the THAI process, unlike conventional ISC processes, significant concentrations of hydrogen (H2) are produced, and the interpretation of its variation can give an indication of the ignition time. The new method is very simple to use, as the percentage of hydrogen in the produced gas starts to take off only after the full establishment of an ISC front, as hydrogen production is associated with high-temperature bond scission reactions in the ISC front. In general, the ignition delay is overestimated to some degree when using this method.

Low-temperature synthesis of high-quality graphene by controlling the carbon-hydrogen ratio of the precursor

A furnace-free inductively coupled plasma chemical vapor deposition (ICP-PECVD) system, which does not require sample heating, was used to grow graphene at a temperature below 300 °C. This studies have found that under low-temperature PECVD growth conditions, liquid precursors are more suitable for preparing low-temperature graphene precursors than gaseous precursors.​​​​ Hence, benzene is used as a carbon precursor to obtain a sheet resistance of approximately 1.24 kΩ sq−1. In this research, it was discovered that the carbon-hydrogen ratio of the precursor molecule is an important factor while using PECVD to grow graphene. This factor affects the quality of graphene and the sheet resistance value —when the carbon–hydrogen ratio for the precursor molecule is 1:1, graphene has the high quality and lowest sheet resistance; when it is less than 1:2, the graphene that cannot be deposited has the worst quality and sheet resistance. Furthermore, we found that methane, a precursor often used to deposit graphene, will etch graphene under low-temperature conditions, and that acetylene can be used as a precursor to deposit graphene. It was further proven that the carbon–hydrogen ratio of the precursor molecules in the PECVD process caused the reduction in the graphene temperature.

Machine learning prediction of bio-oil characteristics quantitatively relating to biomass compositions and pyrolysis conditions

It is crucial to predict the characteristics of pyrolytic bio-oil accurately for its application, but the prediction results are greatly influenced by biomass compositions and pyrolysis conditions. In this work, different biomass compositions analysis (chemical compositions, ultimate and proximate analysis) and pyrolysis conditions (particle size, heating rate and pyrolysis temperature) were successfully used as input to analyze the characteristics of bio-oil by machine learning method. The model based on ultimate analysis is better for regression analysis of the yield, viscosity and oxygen-carbon ratio (O/C) of bio-oil. The model based on chemical compositions is better for regression analysis of calorific value and hydrogen-carbon ratio (H/C) of bio-oil. Moreover, relative error analysis and scatter diagrams were used to analyze the predicted results. In addition, the analysis of partial dependence diagram shows the influence of various factors and the interactions on the target variables. This study provides feasible thinking for the prediction of the characteristics of bio-oil obtained by biomass with different compositions under different pyrolysis conditions.

Effects of diesel from direct and indirect coal liquefaction on combustion and emissions in a six-cylinder turbocharged diesel engine

The aim of this study is to evaluate the effects of diesel from direct coal liquefaction (DDCL) and diesel from indirect coal liquefaction (DICL) on combustion and emissions. A six-cylinder turbocharged diesel engine fueled with DDCL, DICL, petroleum diesel (PD), 58% DDCL, and 42% DICL blended by volume (BD58) is used. The experiments are carried out at 1400 and 2300rpm engine speeds and various engine loads (10%, 25%, 50%, 75%, and 90% of the full-load). The results show that the brake thermal efficiency (BTE) of PD was higher than that of CTL (the maximum difference was 2%) at medium and high loads. At 10% load of 1400 rpm, the CO, HC and formaldehyde emissions of DDCL are 88.9%, 44.3% and 26.5% higher than those of PD respectively, and the CO, HC, and formaldehyde emissions of DICL are 30.1%, 15.3%, and 15.2% lower than those of PD. The differences among four fuels decrease rapidly with the increase of load. The NOX emissions of PD are the highest due to high nitrogen content (102.3 μg/g) and low hydrogen-carbon (H/C) ratio. The fuel with higher cetane number has less formaldehyde emission at low loads, while the fuel with lower H/C has less formaldehyde emission at high loads. The particle size distribution shows a bimodal shape at different loads and the peak particle size of accumulation mode and nucleation mode all increases with the increase of load. The particulate emission of different fuels from high to low is the order of PD > DDCL > BD58 > DICL. In addition, the emissions of polycyclic aromatic hydrocarbons (PAHs) and toxicity equivalent (TE) of PD are highest at all loads. The proportion of soluble organic fractions (SOF) from DDCL, DICL, and BD58 is higher than that of PD.

Self-consistent estimates of emission factors of carboncontaining pollutants from a typical gas flare

This study proposes an approach for estimating the emission of soot, carbon monoxide (CO) and carbondioxide (CO ) from a typical gas flare. The estimations depend on the quantity and varying composition of the 2 natural gas, flame dynamics (represented by the fire Froude number, Fr ) and the equivalence ratio, f, of the fuel- f air mixture. Soot emission estimates are presented as a function of fire Froude number for gases used in labbased test in order to validate the scheme and for two real-world fuel gas compositions. The mass-weighted carbon-hydrogen ratio (C:H) of the fuel gas compositions are 0.25 and 0.29 which are two extreme cases in terms of density. The soot yield of the lab-based test case was scaled up to estimate the soot yield of a full scale flare using the Richardson number as the scaling parameter. When all other variables are held constant at values characteristics of real-world flares, a difference of 16 % in the fuel-gas density, as indicated by the carbonhydrogen ratio, results in an increase of the emission factors (EF) of soot, CO and CO by factors of ~3, ~1.4 2 3 and ~1.7, measured in g/m , respectively. For both fuel gas compositions, the ratio of EF to EF at the fuel- soot CO lean region f < 1) is higher. The ratio lies in the range 0.031 – 0.13 and 0.0012 – 0.0055 for the fuel-lean (f < 1) and fuel-rich (f > 1) regions, respectively. The approach proposed and results obtained may be adopted to generate emissions inventories of emission species associated with gas flaring on regional and global scales.
 Keywords: gas flaring; soot; natural gas; emission factor; black carbon; equivalence ratio

Development of a skeletal surrogate mechanism for emulating combustion characteristics of diesel from direct coal liquefaction

A surrogate describing the oxidation characteristics of Diesel from direct coal liquefaction (DDCL) was proposed in this work. n-dodecane and decalin were chosen as representative species of alkane and cycloalkane hydrocarbons in DDCL according to compositional analysis results. A proportion of 24.6% n-dodecane and 75.4% decalin by mole was determined by emulating real DDCL properties including Cetane number (CN), Hydrogen-Carbon (H/C) ratio, lower heating value (LHV) and density. Sub-mechanisms of n-dodecane and decalin were constructed on top of a detailed C0C6 core mechanism and then sensitivity analysis was used to eliminate unimportant species and reactions. The final version of the skeletal DDCL surrogate mechanism consists of 131 species and 461 reactions. The skeletal mechanism was extensively validated against experimental data including ignition delay times, species concentration profiles and laminar flame speeds for each pure component. Furthermore, diesel engine experiments fueled with DDCL were conducted and the corresponding 3-D CFD simulation results show that the present skeletal mechanism gives reliable performance for combustion behavior as well as NOx and CO emissions predictions, indicating the proposed mechanism can be applied for modeling DDCL in practical engine applications.

Biomass Torrefaction for the Production of High-Grade Solid Biofuels: a Review

Torrefaction of biomass materials has received a tremendous attention over the years due to its ability to produce a high-grade solid biofuel with enhanced durability, excellent grindability, higher bulk density and calorific value, and greater energy density, as compared to the original untreated biomass material. It is a mild pyrolysis treatment technology under inert atmosphere which can improve the chemical and physical properties of raw biomass through the elimination of oxygen, reduction of moisture content, and change of chemical compositions. When raw biomass is mildly pyrolyzed in a default-oxygen or N2 atmosphere at moderate temperatures, the properties of raw biomass including low calorific value, hydrogen-carbon ratio, hygroscopicity, and grindability can be significantly enhanced. In the present review, the operating mechanism of different torrefaction processes including wet, dry, and ionic-liquid-assisted torrefaction is analyzed and discussed. More importantly, the reactor design for commercialization purpose, reaction kinetics and mechanism, economics, and sustainability of biomass torrefaction is discussed in detail. This review is extended to the torrefaction of agro-residue biomass since torrefied agro-residue-based pellets can be produced from agro-residues. The various technological applications of biomass torrefaction are also reviewed and the prospects in ensuring the continuous production of high-grade fuels are summarized.

Formulating of model-based surrogates of jet fuel and diesel fuel by an intelligent methodology with uncertainties analysis

In this study, an intelligent model to formulate fuel surrogates was proposed which includes intelligent surrogate blend optimizer and optimization module of chemistry kinetic mechanism. The components of surrogates were selected from the library of candidates with given compositions by the intelligent surrogate blend optimizer based on the targeted fuel properties. Hence, new jet fuel surrogate (JFS) and diesel fuel surrogate (DFS) models were formulated consisting of five components (n-dodecane/iso-octane/isocetane/decalin/toluene), with specified compositions of each component, respectively. The new surrogates contain major components of the target practical fuels and inherently emulate the key properties including liquid density, viscosity, surface tension, cetane number, hydrogen-carbon ratio, molecular weight, lower heating value and threshold sooting index. Moreover, a robust skeletal oxidation mechanism of fuel surrogate composed of five components was updated and multi-objective optimization algorithm of non-dominated sorting genetic algorithm II (NSGA-II) was introduced to achieve self-adaptive tuning of Arrhenius pre-exponential factor in fuel-related sub-mechanism. Thus, the optimal rate constants could satisfy the predictions of ignition delay times and species concentrations simultaneously. Then Generalized Polynomial Chaos (gPC) was employed to minimize the uncertainty of stochastic input coefficients and its propagation towards ignition behaviours. Consequently, the new surrogate models were well validated against available tested data from practical fuels, and better performance of current JFS model was highlighted when compared with the prediction results by previous model. It is feasible to employ this intelligent model to formulating surrogates for more practical fuels.

THAI process: Determination of the quality of burning from gas composition taking into account the coke gasification and water-gas shift reactions

In the last 13 years, the Toe to Heel Air Injection (THAI) process has been piloted in six heavy oil reservoirs located in three countries.In the THAI process, the production of upgraded oil along with the production of hydrogen is a proven and constant feature. Unlike the conventional in-situ combustion (ISC) process, THAI has a very extended, long zone for the chemical reactions, displaying a considerably longer residence time. In addition to primary reactions like high temperature oxidation and pyrolysis, reactions among the products of primary reactions, like coke gasification and water-gas shift reactions (WGSR) take place. Both in conventional ISC and in THAI, estimate of the burning quality can be made by calculating the apparent hydrogen-carbon ratio (H/C) from the composition of the produced gas. However, in THAI process some of the produced CO2 is not due to oxidation process itself and, therefore, does not characterize the burning process; it is produced by coke gasification and WGSR.An evaluation of this non-burning CO2 is conducted, and a new method, taking into account this non-burning CO2, is developed. This evaluation is based on a correlation between hydrogen and CO2 generated by coke gasification and WGSR, in a simplified form. The method has been applied for the on-going Kerrobert THAI Project (in Saskatchewan, Canada), where CO% was close to zero, while H2% remained high (2–4%)H/C ratio calculated with the old methodology would provide a false impression of a better quality burning in the THAI process, sometimes resulting in unrealistically low H/C values. When using the new method, the calculated H/C ratio would slightly increase. Although slightly increased, it has never taken values higher than 2, confirming that in THAI process the intensity of low temperature oxidation reactions is considerably lower than that in the conventional ISC process.