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Feedstock properties play a crucial role in thermal conversion processes, where understanding the influence of these properties on treatment performance is essential for optimizing both feedstock selection and the overall process. In this study, a series of van Krevelen diagrams were generated to illustrate the impact of H/C and O/C ratios of feedstock on the products obtained from six commonly used thermal conversion techniques: torrefaction, hydrothermal carbonization, hydrothermal liquefaction, hydrothermal gasification, pyrolysis, and gasification. Machine learning methods were employed, utilizing data, methods, and results from corresponding studies in this field. Furthermore, the reliability of the constructed van Krevelen diagrams was analyzed to assess their dependability. The van Krevelen diagrams developed in this work systematically provide visual representations of the relationships between feedstock and products in thermal conversion processes, thereby aiding in optimizing the selection of feedstock and the choice of thermal conversion technique., QC 20231227

Bioenergy with carbon capture and storage (CCS) in iron and steel production offers significant potential for CO2 emission reduction and may even result in carbon-negative steel. With a strong ambition to reach net-zero emissions, some countries, such as Sweden, have recently proposed measures to incentivise bioenergy with CCS (BECCS), which opens a window of opportunities to enable the production of carbon-negative steel. One of the main potential applications of this route is to decarbonise the iron reduction processes that account for 85 % of the total CO2 emission in the iron and steel plants. In this study, gasification is proposed to convert biomass into biosyngas to reduce iron ore directly. Different cases of integrating the biomass gasifier, Direct Reduced Iron (DRI) shaft furnace, and CCS are evaluated through process simulation work. Based on the result of the work, the proposed biosyngas DRI route has comparable energy demand compared to other DRI routes, such as the well-established coal gasification and natural gas DRI route. The proposed process can also capture 0.65-1.13 t of CO2 per t DRI depending on the integration scenarios, which indicates a promising route to achieving carbon-negative steel production., QC 20230607

The decarbonisation of the Swedish iron and steel industry is crucial in achieving Sweden's target to achieve zero net emissions of greenhouse gases (GHG) by 2045. Direct electrification of industrial furnaces could be an important milestone in decarbonising the iron and steel plants. In this study, pilot-scale trials were performed to investigate the possibility of plasma torch application for steel reheating furnaces. A 250 kW DC plasma torch was used to heat the furnace from room to the operating temperature of 1200 degrees C. Different plasma carrier gases were then used to study their impact on the plasma torch efficiency, furnace temperature profile, NOX emission, and steel oxidation. The results show that the furnace could be heated at a relatively uniform temperature and reasonable time. The combination of air and LPG in the plasma generator provides the most uniform temperature distribution and highest plasma torch efficiency, but it generates the highest NOX emission. N2 as plasma gas resulted in notably poorer temperature distribution and lower plasma torch efficiency; however, it can suppress the oxide formations. Meanwhile, CO2 as plasma gas could be a promising option among the studied gas mixtures as it can provide a good heating performance with a low NOX formation. In summary, the current study has proved that it is practical and functionally possible to heat steel using plasma technology., QC 20230424

The use of bioenergy with carbon capture and storage (BECCS) is vital to reaching the desired climate goals. This study proposed a novel process combining anaerobic digestion, pyrolysis, catalytic reforming and methanation (APRM) to produce biomethane and to capture carbon emission from the organic fraction of municipal solid waste (OFMSW). The evaluation of the process was conducted by using modelling software and techno-economic analysis. The process modelling and evaluation result showed that 151.4 kg CH4 and 355.64 kg stored carbon emission can be produced from 1 ton dry matter of OFMSW with an energy efficiency of 0.40. 6.74 MJ electricity was required to capture 1 kg of CO2 via the proposed process. The energy balance of the pyrolysis reaction was investigated. The sensitivities of the pyrolysis temperatures, dewatering technologies and conversion of catalytic reforming on the process performance were analyzed. The result also indicated a positive net profit when using the APRM process to treat the OFMSW based on the calculation of operating expenses and revenue, when the CO2 negativity can be sold as commodity., Not duplicate with Diva 1612933, QC 20220517

Dedicated bioenergy combined with carbon capture and storage are important elements for the mitigation scenarios to limit the global temperature rise within 1.5 °C. Thus, the productions of carbon-negative fuels and chemicals from biomass is a key for accelerating global decarbonisation. The conversion of biomass into syngas has a crucial role in the biomass-based decarbonisation routes. Syngas is an intermediate product for a variety of chemical syntheses to produce hydrogen, methanol, dimethyl ether, jet fuels, alkenes, etc. The use of biomass-derived syngas has also been seen as promising for the productions of carbon-negative metal products. This paper reviews several possible technologies for the production of syngas from biomass, especially related to the technological options and challenges of reforming processes. The scope of the review includes partial oxidation (POX), autothermal reforming (ATR), catalytic partial oxidation (CPO), catalytic steam reforming (CSR) and membrane reforming (MR). Special attention is given to the progress of CSR for biomass-derived vapours as it has gained significant interest in recent years. Heat demand and efficiency together with properties of the reformer catalyst were reviewed more deeply, in order to understand and propose solutions to the problems that arise by the reforming of biomass-derived vapours and that need to be addressed in order to implement the technology on a big scale., QC 20230227

An in-depth knowledge of pyrolytic kinetics is vital for understanding the thermal decomposition process. Numerous experimental studies have investigated the kinetic performance of the pyrolysis of different raw materials. An accurate prediction of pyrolysis kinetics could substantially reduce the efforts of researchers and decrease the cost of experiments. In this work, a model to predict the mean values of model-free activation energies of pyrolysis for five types of feedstocks was successfully constructed using the random forest machine learning method. The coefficient of determination of the fitting result reached a value as high as 0.9964, which indicates significant potential for making a quick initial pyrolytic kinetic estimation using machine learning methods. Specifically, from the results of a partial dependence analysis of the lignocellulose-type feedstock, the atomic ratios of H/C and O/C were found to have negative correlations with the pyrolytic activation energies. However, the effect of the ash content on the activation energy strongly depended on the organic component species present in the lignocellulose feedstocks. This work confirms the possibility of predicting model-free pyrolytic activation energies by utilizing machine learning methods, which can improve the efficiency and understanding of the kinetic analysis of pyrolysis for biomass and fossil investigations., QC 20220613

Bioenergy with carbon capture and storage (BECCS) is one of the prevailing negative carbon emission technologies. Ensuring a hydrogen economy is essential to achieving the carbon-neutral goal. In this regard, the present study contributed by proposing a carbon negative process for producing high purity hydrogen from the organic fraction of municipal solid waste (OFMSW). This integrated process comprises anaerobic digestion, pyrolysis, catalytic reforming, water-gas shift, and pressure swing adsorption technologies. By focusing on Sweden, the proposed process was developed and evaluated through sensitivity analysis, mass and energy balance calculations, techno-economic assessment, and practical feasibility analysis. By employing the optimum operating conditions from the sensitivity analysis, 72.2 kg H2 and 701.47 kg negative CO2 equivalent emissions were obtained by treating 1 ton of dry OFMSW. To achieve these results, 6621.4 MJ electricity and 325 kg of steam were utilized during this process. Based on this techno-economic assessment of implementing the proposed process in Stockholm, when the negative CO2 equivalent emissions are recognized as income, the internal rate of return and the discounted payback period can be obtained as 26% and 4.3 years, respectively. Otherwise, these values will be 13% and 7.2 years., QC 20220617

The current transition to a circular economy model laid the foundations for the development of the Enhanced Landfill Mining concept. Hitherto, a few studies have been performed on the thermochemical valorisation of excavated waste, of which a majority concern incineration or gasification. Nonetheless, no previous studies on excavated waste pyrolysis, including the characterisation of the process products, have been identified. Ergo, this study aims at filling this knowledge gap. The pyrolysis of refuse-derived fuel formed from excavated waste was performed in a lab-scale reactor in the temperature range of 400–700 °C. The non-condensable products (non-condensables) were analysed using Micro GC, whereas the condensable products (condensables) were characterised using GC/MS. Additionally, the distribution of C, H, N, S, O, and Cl among the process products was analysed. The high content of C2–C3 hydrocarbons was detected in non-condensables, whereas the abundance of polycyclic aromatic hydrocarbons (PAHs) was detected among condensable products. However, due to feedstock complex thermal decomposition pattern, no overall tendency, covering the process product properties in relation to the process temperature, can be determined. These fluctuations of composition, therefore, have to be taken into account in the planning of the future utilisation of the excavated waste pyrolysis products. Moreover, two possible risks, connected with the further process products utilisation, were identified – namely, chlorine forming primarily organic compounds and sulphur forming mostly gaseous compounds (H2S)., QC 20200921, NEW-MINE; Horizon 2020 research and innovation programme under the Marie Skłodowska-Curie grant agreement No 721185

The use of bioenergy with carbon capture and storage (BECCS) is vital to reaching the desired climate goals. This study proposed a novel process combining anaerobic digestion, pyrolysis, catalytic reforming and methanation (APRM) to produce biomethane and to capture carbon emission from the organic fraction of municipal solid waste (OFMSW). The evaluation of the process was conducted by using modelling software and techno-economic analysis. The process modelling and evaluation result showed that 151.4 kg CH4 and 355.64 kg stored carbon emission can be produced from 1 ton dry matter of OFMSW with an energy efficiency of 0.40. 6.74 MJ electricity was required to capture 1 kg of CO2 via the proposed process. The energy balance of the pyrolysis reaction was investigated. The sensitivities of the pyrolysis temperatures, dewatering technologies and conversion of catalytic reforming on the process performance were analyzed. The result also indicated a positive net profit when using the APRM process to treat the OFMSW based on the calculation of operating expenses and revenue, when the CO2 negativity can be sold as commodity., QC 20211215

Pyrolysis of municipal solid waste (MSW) represents one of the most promising solutions to recycle materials and recover energy. Two of the main components of MSW are waste cardboard and plastic. In this study, the pyrolysis of cardboard and polyethylene (PE) and the co-pyrolysis of their mixtures were conducted to investigate the synergistic effect by using thermogravimetric analysis. The whole reaction process was divided into four pseudoreactions, namely, hemicellulose, lignin, cellulose, and PE, by using the Frazer-Suzuki deconvolution method. It was found that the co-pyrolysis of cardboard and PE could promote the decomposition degrees of cardboard from 70.28% to 75.31%, when the PE fraction increased from 0 to 75%. However, the presence of cardboard can hinder the heat adsorption of PE, which shifts the peak of the PE reaction to a higher temperature. This results in higher E-a and Delta H double dagger values for PE pyrolysis with an increasing fraction of cardboard. On the other hand, the E-a and Delta H double dagger values of cellulose pyrolysis have their lowest values when the mixing rate is around 50%. This research deepens the understanding of the synergistic effect of co-pyrolysis of cardboard and PE, which supports the potential application of pyrolysis of MSW., QC 20210720

Hydrogen and biocarbon are important materials for the future fossil-free metallurgical industries in Sweden; thus, it is interesting to investigate the process that can simultaneously produce both. Process simulations of biomass pyrolysis coupled with steam reforming and water-gas-shift to produce H-2, biocarbon, and bio-oil are investigated in this work. The process simulation is performed based on a biomass pyrolysis plant currently operating in Sweden. Two co-production schemes are proposed: (1) production of biocarbon and H-2, and (2) production of biocarbon, H-2, and bio-oil. Sensitivity analysis is also performed to investigate the performance of the production schemes under different operating parameters. The results indicated that there are no notable differences in terms of the thermal efficiency for both cases. Varying the bio-oil condenser temperature only slightly changes the system's thermal efficiency by less than 2%. On the other hand, an increase in biomass moisture content from 7 to 14 wt.% can decrease the system's efficiency from 79.0% to 72.6%. Operating expenses are evaluated to elucidate the economics of 3 different cases: (1) no bio-oil production, (2) bio-oil production with the condenser at 50 degrees C, and (3) bio-oil production with the condenser at 130 degrees C. Based on operation expenses (OPEX) and revenue alone, it is found that producing more bio-oil helps improving the economics of the process. However, capital costs and the cost for post-processing of bio-oil should also be considered in the future. The estimated minimum selling price for biocarbon based on OPEX alone is approx. 10 SEK, which is within the range of the current commercial price of charcoal and coke., QC 20210423

Primary fragmentation during rapid pyrolysis is considered to be the critical size reduction mechanism as it determines the particle size distribution and char conversion rates in the fixed bed gasifier. This study aims to investigate the primary fragmentation behavior of Refuse Derived Fuel (RDF) pellets during a rapid pyrolysis process. RDF pellets consisted of different blending ratios of cardboard and polyethylene (PE) were produced by a single-pellet densification process. Pyrolysis tests at temperature ranges of 500-700 degrees C were performed for each pellet type, and the number and particle size of the fragmented particles were analyzed. The results demonstrate that the different composition of RDF causes different particle binding mechanisms that behave differently during pyrolysis. Densification of cardboard particles can maintain the structure of the pellet char at higher temperatures compared to PE, due to the more stable lignin binding mechanism. A modified Fragmentation Ratio (FR) is introduced to quantify the degree of fragmentation. It is shown that a raise of the concentration of PE from 25 to 75 wt% increases the FR value by up to 4.2 times, whereas an increase in pyrolysis temperature from 500 to 700 degrees C only slightly changes the FR values. It can be concluded that the type of materials in the RDF pellet has a more dominating effect on the fragmentation compared to the pyrolysis temperature. Further, the volatile matter content of pellets shows a linear correlation with the FR value, whereas no clear relation is found in the case of the pellet's mechanical strength., QC 20230920

Catalytic tar removal from producer gas is critical for the economic feasibility of Municipal Solid Waste (MSW) gasification in the waste-to-energy(WtE) approach. Nickeland noble-metal catalysts have the highest tar cracking activities, but they increase costs, use scarce materials, and generate dangerous byproducts. To overcome these drawbacks, naturally occurring materials should be used for tar cracking. In this paper, two nanomaterials, synthesized from oyster and mussel waste shells respectively, are used to clean syngas from MSW in a secondary tar cracking unit. We observed that they reform class 1 tar (heavy tars that condense at high temperatures at very low concentrations) into class 3 tar (light hydrocarbons that are not important in condensation) and benzene. Although both catalysts' composition and textural properties were identical, crystallite size and especially specific surface area variation was enough to generate a change in product selectivity. A larger crystallite size and SSA shows a soot yield reduction of 95% with respect to the non-catalytic case, simultaneously increasing the H-2/CO at 1000 degrees C., QC 20210126

Gasification of excavated landfill waste is one of the promising options to improve the added-value chain during remediation of problematic old landfill sites. Steam gasification is considered as a favorable route to convert landfill waste into H-2-rich syngas. Co-gasification of such a poor quality landfill waste with biochar or biomass would be beneficial to enhance the H-2 concentration in the syngas, as well as to improve the gasification performance. In this work, steam co-gasification of landfill waste with biochar or biomass was carried out in a lab-scale reactor. The effect of the fuel blending ratio was investigated by varying the auxiliary fuel content in the range of 15-35 wt%. Moreover, co-gasification tests were carried out at temperatures between 800 and 1000 degrees C. The results indicate that adding either biomass or biochar enhances the H-2 yield, where the latter accounts for the syngas with the highest H-2 concentration. At 800 degrees C, the addition of 35 wt% biochar can enhance the H-2 concentration from 38 to 54 vol%, and lowering the tar yield from 0.050 to 0.014 g/g-fuel-daf. No apparent synergetic effect was observed in the case of biomass co-gasification, which might cause by the high Si content of landfill waste. In contrast, the H-2 production increases non-linearly with the biochar share in the fuel, which indicates that a significant synergetic effect occurs during co-gasification due to the reforming of tar over biochar. Increasing the temperature of biochar co-gasification from 800 to 1000 degrees C elevates the H-2 concentration, but decreases the H-2/CO ratio and increases the tar yield. Furthermore, the addition of biochar also enhances the gasification efficiency, as indicated by increased values of the energy yield ratio., QC 20200915

Gasification is one of the most important methods for converting biomass to syngas currently used in energy production. However, tar content in syngas limits its direct use and thus requires additional removal techniques. The modelling of tar formation, conversion and destruction along a gasifier could give a wider understanding of the process and subsequently help in tar elimination and reduction. However, tar complexity, which contains hundreds of species, makes the modelling process hard and computationally intensive, because the chemistry of the formation and the combustion of many species have not yet been fully studied. In this work, a detailed kinetic model for the evolution and formation of tar from downdraft gasifiers, for the first-time, was built. The model incorporates four main tar species (benzene, naphthalene, toluene, and phenol) with a total of eighteen different kinetic reactions implemented in the code for every zone. Experimental work was carried out to initially validate the results of the kinetic code and found a good agreement. Further experiments were conducted at three different equivalence ratios (ERs) and at three different temperatures (800, 900, and 1100 °C). Sensitivity analysis was then carried out by the kinetic code to optimise the working parameters of a downdraft gasifier that led to a higher calorific value of syngas. The results reveal that a tar evolution model is more accurate for wood biomass materials and that using ER around 0.3, and moisture content levels lower than 10% lead to the production of higher value syngas with lower tar amounts., QC 20191202. QC 20200109

This study proposes a novel system to efficiently produce hydrogen from microalgae, based on supercritical water gasification and syngas chemical looping, and its conversion to methylcyclohexane. The process consists of a gasifier, a syngas chemical looping reactor, and a methylcyclohexane synthesis reactor as the main units. Microalgae are converted to syngas in the supercritical water gasification reactor. Thereafter, the produced syngas is introduced into the syngas chemical looping module to produce pure hydrogen and a separated carbon dioxide stream. The hydrogen is then reacted with toluene through the hydrogenation reaction to produce methylcyclohexane as a hydrogen carrier. The heat released from the methylcyclohexane synthesis module and chemical looping combustor is utilized to sustain the thermal balance of the supercritical water gasification unit. The system performance is observed under different feed moisture contents, operating temperatures in the supercritical water gasification unit, and operating pressures in the syngas chemical looping unit. A steady-state process simulation of Aspen Plus software is used for this purpose. The proposed integrated system exhibits of approximately 13.7%, 45.3%, and 59.1% for power generation efficiency, hydrogen production efficiency, and total energy efficiency, which demonstrates an efficient process of hydrogen production. The preliminary economic assessment shows that more than half of the operating cost accounts for microalgae production. This indicates the microalgae feedstock is one of the critical cost drivers in the microalgae-to-hydrogen production system., QC 20190731

As the world is transitioning towards a low-carbon economy, it is becoming important to develop ways to reduce carbon dioxide (CO2) emissions. Chemical looping, a low carbon technology for the industry, is considered as a potential breakthrough technology and a viable option for efficient fuel conversion and carbon capture and storage, with the successful completion of pilot plant trials in the USA. The conversion of captured CO2 to methanol can be considered a promising method for significantly reducing CO2 emissions, while the produced methanol can be used as a convenient energy carrier for hydrogen storage. This study focuses on a process of converting microalgae, a potential fuel feedstock, into methanol by utilizing CO2 generated within the process. The specific focus lies on the conversion of the microalgae into methanol through dual-stage chemical looping and efficient process integration with maximum energy recovery. Aspen Plus® was used to simulate the facility producing 42 mt (metric tons) methanol/h using 60.1 mt/h CO2 and 8.2 mt/h H2. The process was divided into four-module operations: drying, chemical looping gasification, syngas chemical looping, and methanol synthesis. The energy efficiency of this process is around 45-51% which is comparative with the concentrated CO2-based methanol and typical biomass-based syngas to methanol processes. Because the separated CO2 obtained via chemical looping is utilized for methanol synthesis, the carbon-negative value is attained., QC 20190527

Hydrogen (H-2) production and storage technologies are the main challenges in the realization of H-2 utilization in which the goal is to achieve high conversion efficiencies and a high storage density. In this study, microalgae gasification and ammonia (NH3) production are proposed to efficiently convert microalgae to NH3 for efficient H-2 storage. The integrated system comprises drying, gasification, syngas chemical looping (SCL), NH3 synthesis, and power generation. Microalgae are converted to syngas in the gasification module and then introduced into the SCL module to produce high-purity H-2 and a separated carbon dioxide (CO2) stream. SCL is also employed to produce a nitrogen (N-2)-rich stream, which can replace a conventional air separation unit (ASU) system. The three operating parameters that are evaluated in this study include the steam to biomass (S/B) ratio during gasification, reducer operating temperature during chemical looping, and recycle to feed streams ratio. An increase in the S/B ratio has a negative effect on the total energy efficiency because the efficiency decreases owing to the reduced production of H-2 in the oxidizer. To maximize the efficiency of NH3 production, a higher recycle ratio is favorable. The proposed integrated system can obtain high total energy efficiency of up to 64.3%, comprising 63.8% NH3 production efficiency and 0.05% power generation efficiency., QC 20190709

Mixed plastics and papers are two of the main fractions in municipal solid waste which is a critical environmental issue today. Recovering energy and chemicals from this waste stream by pyrolysis is one of the favorable options to achieve a circular economy. While pyrolysis products from plastics are mainly hydrocarbons, pyrolysis products from paper/biomass are highly oxygenated. The different nature of the two pyrolysis products results in different treatments and applications as well as economic values. Therefore, separation of these two products by multi-step pyrolysis based on their different decomposition temperatures could be beneficial for downstream processes to recover materials, chemicals and/or energy. In this work, stepwise pyrolysis of mixed plastics and paper waste was performed in a batch type fixed bed reactor using two different pyrolysis temperatures. Neat plastic materials (polystyrene, polyethylene) and cellulose mixtures were used as starting materials. Then, the same conditions were applied to a mixed plastics and paper residue stream derived from paper recycling process. The condensable products were analyzed by GC/MS. It was found that pyrolysis temperatures during the first and second step of 350 and 500 °C resulted in a better separation of the oxygenated and hydrocarbon condensates than when a lower pyrolysis temperature (300 °C) was used in the first step. The products from the first step were derived from cellulose with some heavy fraction of styrene oligomers, while the products from the second step were mainly hydrocarbons derived from polystyrene and polyethylene. This thus shows that stepwise pyrolysis can separate the products from these materials, although with some degree of overlapping products. Indications of interaction between PS and cellulose during stepwise pyrolysis were observed including an increase in char yield, a decrease in liquid yield from the first temperature step and changes in liquid composition, compared to st, QC 20181119