Specific Consumption Research Articles

Keeping the global consumption within the planetary boundaries.

The disparity in environmental impacts across different countries has been widely acknowledged1,2. However, ascertaining the specific responsibility within the complex interactions of economies and consumption groups remains a challenging endeavour3-5. Here, using an expenditure database that includes up to 201 consumption groups across 168 countries, we investigate the distribution of 6 environmental footprint indicators and assess the impact of specific consumption expenditures on planetary boundary transgressions. We show that 31-67% and 51-91% of the planetary boundary breaching responsibility could be attributed to the global top 10% and top 20% of consumers, respectively, from both developed and developing countries. By following an effective mitigation pathway, the global top 20% of consumers could adopt the consumption levels and patterns that have the lowest environmental impacts within their quintile, yielding a reduction of 25-53% in environmental pressure. In this scenario, actions focused solely on the food and services sectors would reduce environmental pressure enough to bring land-system change and biosphere integrity back within their respective planetary boundaries. Our study highlights the critical need to focus on high-expenditure consumers for effectively addressing planetary boundary transgressions.

REDUCING THE VISCOSITY OF THE OIL MIXTURE BY A ROTARY PULSE APPARATUS IN UKHTA — YAROSLAVL OIL PIPELINE

Physical methods of exposure can be used to improve the rheological characteristics of viscous, resinous oils, the transportation of which through main pipelines requires additional operating costs. The authors of this article evaluated the effectiveness of the method for improving oil rheology due to multifactorial effects (shear loads, high–amplitude pressure pulses, developed turbulence) on a sample of a mixture of oils of the Ukhta - Yaroslavl oil pipeline in a rotary pulse apparatus (RIA). The specific power consumption for processing an oil sample was 2.84 kWh/m3. The initial rheological and physico-chemical parameters of the studied oil are described, according to which it is characterized as heavy, viscous, highly resinous oil. The analysis of the flow curves showed that, by the nature of the flow, the sample of a mixture of oils from the Ukhta — Yaroslavl main oil pipeline belongs to Newtonian liquids. The evaluation of the effectiveness of the multifactorial effect on the oil sample implemented in RIA was carried out using dimensionless coefficients showing the ratio of dynamic viscosity, the specific power required to maintain the flow of oil in a rotary viscometer before and after physical exposure to oil, as well as the ratio of the change in the energy of thixotropy of oil to the energy spent on the processing process. The samples were processed in an RIA-based installation, in which pressure pulsations, developed turbulence, and large shear loads are generated in the liquid flow. When comparing the viscosity values of untreated and treated mixed oil in a rotary pulse apparatus, the dynamic viscosity measured at 20 °C decreased by 8 %. The component composition of the oil after processing in RIA has practically not changed. Measuring the viscosity of oil before processing and immediately after processing in RIA shows a decrease in viscosity by more than two times, since the temperature of the oil flow increases after passing through RIA by more than 10 °C. The increase in oil temperature during processing is due to large shear stresses during its flow in slit channels and in the gap between the rotor and stator due to the large amplitude of pressure pulsations and flow velocity.The relaxation time of the rheological parameters of the treated oil was seven days.

Development of a Prediction Model for Specific Fuel Consumption in Rotary Tillage Based on Actual Operation

Tractor fuel consumption has typically been predicted using indoor test results under specific conditions. This study analyzes the factors affecting fuel consumption during rotary tillage in actual fields and develops a prediction model. The test field was divided into sections using a grid method, and rotary tillage operations were performed to measure various parameters, including soil strength, tractor’s transmission and PTO gear stages, tillage pitch, travel speed, engine and PTO shaft torque and speed, and fuel consumption. Pearson correlation identified variables affecting specific fuel consumption, and regression analysis was used to develop a prediction model. The model’s accuracy was analyzed using the coefficient of determination (R2) and root mean square error (RMSE), and it was compared with the ASABE’s fuel consumption prediction model. The test results showed that higher transmission and PTO gear stages, and tillage pitch decreased specific fuel consumption, while soil strength had no significant effect. Thus, operating at higher gear and PTO stages within suitable conditions enhances energy efficiency in rotary tillage. Statistical analysis showed that specific fuel consumption significantly correlated with tractor travel speed, PTO shaft power, and PTO shaft speed. The prediction model, including these variables, had the highest accuracy with R2 of 0.91 and RMSE of 0.011 L/kW·h. The developed prediction model showed significantly improved accuracy compared to the ASABE model, indicating that it can predict specific fuel consumption based on key operational variables in actual rotary tillage operations.

Precise regulating the specific oxygen consumption rate to strengthen the CoQ10 biosynthesis by Rhodobater sphaeroides

Coenzyme Q10 (CoQ10) is the most consumed dietary supplement and mainly biosynthesized by aerobic fermentation of Rhodobacter sphaeroides (R. sphaeroides). Oxygen supply was identified as a bottleneck for improving CoQ10 yield in R. sphaeroides. In this study, a precise regulation strategy based on dielectric spectroscopy (DS) was applied to further improve CoQ10 biosynthesis by R. sphaeroide. First, a quantitative response model among viable cells, cell morphology, and oxygen uptake rate (OUR) was established. DS could be used to detect viable R. sphaeroides cells, and the relationship among cell morphology, CoQ10 biosynthesis, and OUR was found to be significant. Based on this model, the online specific oxygen consumption rate (QO2) control strategy was successfully applied to the CoQ10 fermentation process. QO2 controlled at 0.07 ± 0.01 × 10− 7mmol/cell/h was most favorable for CoQ10 biosynthesis, resulting in a 28.3% increase in CoQ10 production. Based on the multi-parameters analysis and online QO2 control, a precise online nutrient feeding strategy was established using conductivity detected by DS. CoQ10 production was improved by 35%, reaching 3384 mg/L in 50 L bioreactors. This online control strategy would be effectively applied for improving industrial CoQ10 production, and the precise fermentation control strategy could also be applied to other fermentation process.

Design and optimization of large-scale natural gas liquefaction process based on triple refrigeration cycles

In large-scale natural gas liquefaction, minimizing specific energy consumption has consistently been a primary objective. This study aims to develop a large-scale natural gas liquefaction process that balances energy efficiency and cost-effectiveness, presenting a viable option for industrial production. By employing a refrigerant strategy of “propane + mixed refrigerant + mixed refrigerant”, a novel large-scale natural gas liquefaction process based on triple refrigeration cycles (TRC) is proposed. To address the challenge of boil-off gas (BOG) re-liquefaction, the TRC process is further refined to integrate BOG re-liquefaction (TRC-BR). Thermodynamic models are built for the proposed TRC and TRC-BR processes, as well as the propane pre-cooled mixed refrigerant (C3MR) and AP-X processes as baseline cases. Global optimization is conducted using the Particle Swarm Optimization (PSO) algorithm, with the specific power consumption (SPC) serves as the objective function. The results reveal that the SPC of the TRC and TRC-BR processes are 0.2726 and 0.2704 kWh/kg-LNG respectively. Compared with the C3MR and AP-X processes, the SPC of the TRC decrease by 1.54% and 4.84%, respectively. The total investments for the TRC and TRC-BR processes are estimated at a similar level compared to the baseline cases, demonstrating their significant potential for industrial application.

Comprehensive investigation of gas hold-up in a double coaxial mixer with shear-thinning fluids exhibiting yield stress: Experimental, numerical, and artificial neural network approaches

This study addresses the challenge of uneven gas dispersion in yield-stress, non-Newtonian fluids, commonly encountered in industries such as biopharmaceuticals, cosmetics, and food processing. While previous research demonstrated the advantages of dual coaxial mixers for pseudoplastic fluids, limited attention has been given to aerating yield-pseudoplastic fluids with higher aspect ratios. This study bridges that gap by investigating both local and global gas hold-up under various conditions, utilizing electrical resistance tomography and computational fluid dynamics. Key findings showed that increasing the anchor speed from stationary to 30 rpm significantly enhanced aeration efficiency (gas hold-up per specific power consumption), with improvements of 78 % in UP-CO mode and 25 % in UP-COUNTER mode at Nc = 350 rpm and Qg = 20 L/min. These results underscore enhanced gas dispersion under specific operating conditions, driving overall process intensification. To ensure accurate prediction of gas hold-up, both dimensional and dimensionless empirical correlations, along with an artificial neural networks (ANNs) model, were developed. The ANNs model exhibited superior accuracy, achieving R² values of 0.99 for both rotation modes, outperforming empirical models, which achieved R² values of 0.90 and 0.89 for UP-CO and UP-COUNTER modes, respectively.

Exergy efficiency improvement by compression heat recovery for an integrated natural gas liquefaction-CO2 capture-NGL recovery process

For liquefied natual gas production, cryogenic distillation offers lower thermal energy consumption and a more compact footprint for carbon capture unit than the widely used chemical absorption. However, the reduction in thermal energy consumption comes at the cost of increased power consumption. To reduce the power consumption of cryogenic distillation based natural gas lqiuefaction plants, an integrated process for liquefied natual gas production, cryogenic CO2 capture and natural gas liquids recovery is proposed, which is called the base process. This base process is further integrated with a heat recovery unit (Organic Rankine cycle or Kalina cycle) to investigate the optimal utilization of compression heat in the system. The proposed processes are modeled in Aspen HYSYS and optimized using a genetic algorithm installed in Matlab. The results show that specific power consumption of the base case is 0.385 kWh/Nm3 NG. Due to the lack of compression heat recovery, significant exergy loss occurs at the water coolers, accounting for approximately 37 % of the total system exergy destruction. Among the evaluated methods, the supercritical Organic Rankine cycle, using R1234ze as the working fluid, recovers approximately 60 % of the exergy from compression heat with an 8.7 % improvement in system exergy efficiency. The subcritical Organic Rankine cycle, using R600a as the working fluid, achieves a slightly lower exergy efficiency improvement of 7.1 %. The Kalina cycle, while less efficient, still improves the system’s exergy efficiency by 6.3 %. Economic analysis reveals that the total annualized cost of the base process is $8,441,416, with a levelized cost of $0.1411/kg. The subcritical Organic Rankine Cycle provides the most cost-effective solution, with the lowest total annualized cost of $8,305,154 and a levelized cost of $0.1402/kg. The Kalina cycle ranks second in cost-effectiveness, with a total annualized cost of $8,345,914 and a levelized cost of $0.1405/kg NG. Although the supercritical ORC requires the highest capital investment, it proves more cost-effective than the base process due to its reduced annual operating costs.

Optimal dimensioning of renewable energy generation and storage systems

With high energy demand and large available area, agricultural farms offer significant potential for renewable energy investments, like photovoltaic systems and electrical energy storages. However, the profitability of such investments depends strongly on self-consumption, so accurate planning requires computation-intensive simulation and optimization considering local consumption. This study presents a novel methodology for the optimal dimensioning and configuration of photovoltaic systems and electrical energy storages using efficient techniques from continuous non-linear optimization. Combining physical and economic models with measured consumption data, an investment’s net present value over 20 years is maximized. Using gradient-based solver WORHP, the simulation, optimal control, and optimal dimensioning of the local energy system are calculated simultaneously, allowing for efficient computation over an entire year of hourly data to capture both daily and seasonal variations.The approach is demonstrated with simple use cases, including an exemplary day of a dairy farm’s consumption, for which optimal systems with and without storage achieve 77% and 43% of autarky, respectively. Saturation effects of optimal plant size can be observed when sizes are large enough for optimal self-consumption but not expanded further for grid export. With energy storage, this saturation is reached at higher values. Optimizing photovoltaic plants with different orientations to match the specific consumption patterns characteristic of the dairy farm achieves similar autarky as a single plant while reducing investment costs by more than 20%. While thorough validation and comparison against heuristic methods predominantly used in the field is part of ongoing research, the presented use cases demonstrate the flexibility and efficiency of the proposed method and highlight its promise as a planning tool in the agricultural domain and beyond.

Optimizing Compressed Air Operations for Electrical Energy Savings: A Case Study in Pharmaceutical Packaging Manufacturing

This study in pharmaceutical packaging manufacturing focuses on improving compressed air efficiency through targeted strategies at both the source and user levels by establishing a baseline to analyze energy consumption patterns. Key measures, including minimizing air leaks, adjusting pressure, and optimizing compressor performance, aim to achieve a 20-50% increase in efficiency, thereby supporting environmental sustainability. The User Point and Source Point approaches are expected to lower Specific Power Consumption (SPC), with data collected from December 2020 to May 2022 providing insights into potential energy savings. Establishing this baseline, based on machine runtime and productivity, offers a solid foundation for evaluation. Results show a 23% reduction in compressor electricity usage and a 7-8% decrease in compressed air consumption. A structured improvement process and strong collaboration between engineering and management are essential for enhancing productivity and achieving sustainable energy efficiency in the industrial sector.

Optimization of BOG Reliquefaction Process of Carbon Dioxide Considering Nitrogen Content

<i>As the importance of carbon capture and storage (CCS) technology increases for greenhouse gas reduction, CO<sub>2</sub> transportation technology is also becoming crucial. Efficiently handling boil-off gas (BOG) generated during voyages is particularly important. This paper proposes a process incorporating two-stage separation and mixed refrigerants to reliquefy CO<sub>2</sub> BOG containing nitrogen efficiently. This process was optimized based on specific power consumption (SPC) criteria and compared with the conventional single-stage separation using an ammonia refrigerant. The two-stage separation allows the removal of non-condensable gases, such as nitrogen, before expansion, and the use of mixed refrigerants enables more efficient heat exchange than ammonia refrigerants, improving the reliquefaction rate. As a result, the proposed process reduced SPC by up to 8.8 % with a nitrogen content of 5 mol% and up to 74.7 % with a nitrogen content of 15 mol%. In addition, the proposed process achieved a reliquefaction rate of over 74.2 % across all nitrogen content ranges of 5–15 mol%.</i>

Aerodynamic analysis and hygrothermal transfer characteristics of cellulose evaporative cooling pads: A case study applied to protected agriculture

Evaporative cooling pads are clean media for cost-effective temperature management. However, the spatially integrated microclimate resulting from heat and mass transfer in the evaporative cooling pad is an uncertain and nonlinear complexity. Therefore, this purpose of this study is to present an innovative prediction model with computational fluid dynamics and evaluate the operating scenarios and geometrical properties of wet pads from quantitative metrics such as saturation efficiency and pressure drop. The reliability of the established numerical model of wet pads was verified by wind tunnel experiments and existing experiments, which predicted the outlet conditions in satisfactory conformity. The results showed that a wet pad with 8 mm ripple height and 19.6 mm ripple distance exhibits the best prospective, with energy consumption and specific water consumption reduced by 45.28 % and 26.26 %, respectively. Meanwhile, the cross strategy of 45_45° corrugation obliquity reduces the pressure drop by 18.95 %, providing uniform supply air distributions. The heat exchange of the wet pad is mainly concentrated within the first 35 mm from the inlet section, while the mass exchange of the wet pad is concentrated within the first 60 mm. The range of frontal air velocity with 0.9–2.5 m/s is recommend for the evaporative cooling system.

Medium-Duty Road Freight Transport—Investigation of Consumption and Greenhouse Gas Emissions of Battery Electric and Fuel Cell Trucks with Model-Based Predictions Until 2050

The present work intends to make a scientific contribution to future drive technology in medium-duty road freight transportation that is as objective and fact-based as possible. In cooperation with a medium-sized forwarding company, 1-day transports, previously driven with diesel trucks, were examined. Using a physically based model, which was first validated by comparing simulated CNG drive data with real-world diesel data, the findings were transferred to battery electric trucks (BETs) and fuel cell trucks (FCETs) and extrapolated to 2050 based on expected technological developments. The model makes statements based on the results of the investigated application regarding specific consumption, greenhouse gas (GHG) emissions, consumption shares and recuperation. The CNG combustion technology (ICET-CNG) serves as a reference. BETs in this application have the lowest emission and consumption values: BET2050 will consume a third of the energy and emit a fifth of the GHGs of ICET-CNG2024. The weight of the battery leads to higher consumption values. FCETs have higher fuel consumption due to their longer drive trains. This is partially compensated by their lower weight: FCET2050 will consume 40% of the energy and emit a third of the GHGs of ICET2024. In long-distance traffic, aerodynamic drag is the dominant consumption factor, accounting for 40%, which should be addressed in further truck development. Recuperation extends the range by 3–7%.

The Absence of Phasins PhbP2 and PhbP3 in Azotobacter vinelandii Determines the Growth and Poly-3-hydroxybutyrate Synthesis.

Phasins are proteins located on the surface of poly-3-hydroxybutyrate (P3HB) granules that affect the metabolism of the polymer, the size and number of the granules, and some also have stress-protecting and growth-promoting effects. This study evaluated the effect of inactivating two new phasins (PhbP2 or PhbP3) on the cellular growth, production, and molecular mass of P3HB in cultures under low or high oxygen transfer rates (OTR). The results revealed that under high OTRₘₐₓ conditions (between 8.1 and 8.9 mmol L-1 h-1), the absence of phasins PhbP2 and PhbP3 resulted in a strong negative effect on the growth rate; in contrast, the rates of specific oxygen consumption increased in both cases. This behavior was not observed under a low oxygen transfer rate (3.9 ± 0.71 mol L-1 h-1), where cellular growth and oxygen consumption were the same for the different strains evaluated. It was observed that at high OTR, the absence of PhbP3 affected the production of P3HB, decreasing it by 30% at the end of cultivation. In contrast, the molecular weight remained constant over time. In summary, the absence of phasin PhbP3 significantly impacted the growth rate and polymer synthesis, particularly at high maximum oxygen transfer rates (OTRₘₐₓ).

Enhancing the biodegradation of hydrophobic volatile organic compounds: A study on microbial consortia adaptation and the role of surfactants

The emission of hydrophobic Volatile Organic Compounds (VOCs) is a serious environmental issue. Typically, biofilters (BFs) are employed for their treatment, with the potential enhancement of mass transfer through the addition of surfactants. However, disparate results in previous studies have been observed, attributed to uncontrolled conditions during the introduction of surfactants to BFs. Additionally, there has been limited exploration of microbial consortium adaptation to surfactants. To address these gaps, this study followed two approaches. First, the long-term (247 days) removal of cyclohexane was studied in a stirred tank bioreactor (STBR) inoculated with Rhodococcus erythropolys E1 and using Tween 80 at three times the critical micelle concentration (CMC). Second, the short-term (9 days) impact of two (bio)surfactants [Tween 80 (1 × CMC) and Quillaja Saponin (QS, 1 × CMC)] on the removal of cyclohexane, hexane and toluene was investigated in batch tests using three types of inocula: a pure culture of Rhodococcus erythropolys E1 (X0), a microbial consortium adapted to cyclohexane (X1), and a microbial consortium adapted to cyclohexane with Tween 80 (X2). For long-term operation, the addition of Tween 80 at 3 × CMC improved cyclohexane removal efficiency (RE) to 87 ± 1% (elimination capacity, EC = 145 ± 25 mg m−3 h−1, gas residence time, GRT = 20 min, inlet concentration, Cin = 14.9 ± 2.5 ppmv), compared to a RE of 32 ± 9% (EC = 44 ± 8 mg m−3 h−1, GRT = 20 min, Cin = 15.1 ± 0.7 ppmv) under similar conditions without surfactants. For short-term operation, the addition of QS at 1 × CMC significantly increased biomass growth, resulting in lower maximum specific consumption rates for X1 and X2 compared to scenarios without surfactants or 1 × CMC Tween 80. The most abundant genera in X1 and X2 were Paludisphaera (26-23%), 67-14 genus (17–23%), and Rhodococcus (9–18%), respectively.

Application of diamond abrasive tools in the processing of technical ceramics in parts of mining machines

Technological development of mining equipment is largely initiated by the improvement of technologies and tools for its production, including in the field of surface treatment quality, which, in turn, determines the reliability and productivity of machines. The use of technical ceramics in designing parts and assemblies of mining machines allows for significantly improved technical and produc-tion characteristics since the quality of the parts' surface treatment is traditionally carried out with diamond-containing tools. The dia-mond tools with ceramic bonds have the highest grinding perfor-mance at the abrasive shaping of ceramics. The tribotechnical characteristics of tools made of a material with a ceramic structure hardened with microdipersed diamond grains are investigated in this work. On the basis of the classical approach to the deformation of rough surfaces, a model has been constructed that makes it possible to estimate the influence of the structural components of a dia-mond mineraloceramic tool on the wear of technical ceramics. The relations for calculation of grinding productivity, diamond content in the worn layer of the abrasive tool and the value of specific dia-mond consumption have been obtained. Experimental studies con-firmed the theoretical conclusions. It has been established that the greatest influence on grinding productivity is exerted by diamond granularity, loading and speed modes; diamond concentration significantly determines the relative wear resistance of the abrasive tool. The obtained relations will be useful in the design of diamond-containing tools for processing technical ceramics, which is increas-ingly used in the design of mining machines since its market is grow-ing dynamically around the world.

Improving Productivity and Sustainability by Using Six Sigma Methodology: A Case Study on Indian Cement Manufacturing Industry

This article presents a detailed and thorough analysis of the Six Sigma DMAIC (Define, Measure, Analyze, Improve, Control) methodology’s application in a cement plant located in Odisha, India, concentrating on the enhancement of productivity. The initial operational context is carefully unveiled, portraying a daily productivity of 3178 tons. The systematic and strategic implementation of the Six Sigma DMAIC approach leads to a remarkable 7.7% increase, culminating in an elevated daily productivity of 3425 tons. Moving beyond the productivity paradigm, the study delves into the intricate dimensions of environmental sustainability, scrutinizing specific water consumption, specific energy consumption, specific emissions, and specific wastage. The outcomes portray positive advancements in these sustainability metrics, signifying a successful amalgamation of heightened productivity and a heightened sense of environmental responsibility. Moreover, the study underscores a substantial annual cost benefit of 10 crores, affirming the economic viability inherent in the Six Sigma initiative. The distinctiveness of this research lies in its meticulous scrutiny of productivity enhancements within the Six Sigma DMAIC framework, spotlighting its direct and advantageous influence on the industry’s sustainability performance. This comprehensive investigation is poised to provide valuable insights to organizations seeking a harmonious equilibrium between operational efficiency and environmental stewardship, encapsulating the essence of Six Sigma, DMAIC, Productivity, and environmental sustainability.

Dietary fibre and metabolic health: A clinical primer.

Dietary fibres consist of a heterogeneous group of carbohydrate polymers which resist digestion by human gastrointestinal enzymes. Consumption of dietary fibre has been linked with innumerable health benefits encompassing the foundational pillars of metabolic health from obesity to hypertension, dyslipidaemia, and type 2 diabetes mellitus (T2DM), with many of these benefits linked with metabolites produced by the fermentation of fibre by gut microbes [1]. The potential of dietary fibre to provide a safe and effective nonpharmacologic complementary tool with which to combat the evolving consequences of the obesity epidemic has recently garnered tremendous attention in both medical literature and lay media alike. HIGHLIGHTS: Consumption of dietary fibre has been linked with innumerable health benefits encompassing the foundational pillars of metabolic health with many of these benefits linked with metabolites produced by the fermentation of fibre by gut microbes At the present time clinicians are faced with an impossible task in which there is rapidly mounting evidence for dietary fibres advancing metabolic health, but little practical options for healthcare providers other than to simply recommend patients consume more fibre. Benefits of fibre intake may perhaps be maximised in an individual by matching specific fibre consumption with existing microbial functional characteristics If dietary fibres could be demonstrated to act as successful adjuncts to sustain or improve standard of care therapies or even alleviate common gastrointestinal side effects associated with current treatments, they would be an invaluable tool in our metabolic health armamentarium. Neither Dr. Madsen or I have any financial conflicts of interest pertinent to the contents of this manuscript.

Effects of industrial hydrogen-rich gases on the performance of the spark ignition engine under various combustion modes

Hydrogen is emerging as a promising alternative to traditional fossil fuels for the transportation. Additionally, the hydrogen-rich gases (HRG) can produce on a large scale during the process of chemical production. In this study, the influences of HRG on the performance behaviors of the spark ignition (SI) engine are comprehensively analyzed under various combustion modes and operating conditions. The experimental results indicate that with increasing the lambda, the torque of the test engine can maintain the target value under equivalent ratio and lean combustion modes, while it sharply decreases under ultra-lean combustion. When the value of the lambda is 1.5, the brake thermal efficiency (BTE) and brake specific hydrogen consumption (BSHC) of the HRG SI engine respectively reach up to 33.6% and 89.1 g/kW.h, yielding superior fuel economy. The NOx emissions of the HRG SI engine firstly increase and then decrease with increasing lambda, reaching the peak value at the lambda of 1.1. In addition, the NOx, CO, and HC emissions of the HRG SI engine greatly reduce when the lambda is approximately 1.5. Consequently, using HRG partially substitute the traditional fossil gasoline in the SI engine can benefit to achieve energy conservation and emissions reduction in transportation section.

Analysis of Biomass Co-firing Combustion Test using Corn Cobs at Punagaya CFPP as A Green Energy Alternative

Abstract Indonesia is determined to reduce fossil fuels by 2060 set a national renewable energy mix target of 23% by 2025 and be free of fossil fuels by 2060. One of the PLN’s (a national electrical company in Indonesia) efforts to increase carbon emissions reduction and strengthen local new renewable energy is co-firing biomass on CFPP. Indonesia, which is located in a tropical area, has a large potential for biomass resources. Corn cob, one of the biomass types, has a big potential to replace coal as fuel in CFPP especially in Jeneponto Region, South Sulawesi. By utilizing corn cobs as a fuel with a co-firing mechanism, it can generate green energy. The methodology for assessing the corn cob co-firing combustion test’s performance at Punagaya CFPP is presented in this paper. It is based on a multi-criteria assessment designed to examine the technical, financial, and environmental effects of operating parameters with a mixture composition of 95% coal and 5% corn cobs at 70 MW load for 10 hours. From the test results in terms of operational aspects, the parameters have changed but it still in the normal operating range; FEGT increased by 5.3°C, bed temperature increased by 8.9°C, air chamber pressure decreased by 0.05 kPa, and total airflow decreased by 4.5 T/h. From the financial aspect, it has benefited from a decrease in the value of Specific Fuel Consumption (SFC), which is 0.014 kg/kWh compared to 100% coal. From the environmental aspect, the overall results of emission parameters are still by environmental quality standards and have decreased for NOx and SO2 parameters.

Gas–liquid mixing performance of a non‐Newtonian fluid in a multiple‐impeller agitated tank

AbstractBACKGROUNDThis target is to decide power input and gas hold‐up for gas–liquid mixing aqueous CMC solutions. The analysis considers the impact by varying the impeller speed and gas flow rates in a stirred tank bioreactor of three kinds of multiple impellers. The effects of the impeller type, rheology, and operating conditions were investigated on power drawn, relative power demand (RPD), gas holdup, and volumetric mass transfer coefficient.RESULTCompared to the Rushton turbine (6RT) and 4‐pitch blade (4PBT) impeller, the propeller (3PP) impeller presented a minimal event of the gassing on the RPD. 4PBT impeller has shown a higher gas hold‐up compared to the Rushton turbine and propeller impellers. The aerated agitated tank was established a dimensionless correlation for the RPD as a function of flow number and web number. Besides, the gas–liquid agitated system was also introduced a dimensionless correlation to compute the overall gas hold‐up as a function of specific power consumption. For the maximum dispersion mixing intensity, the impeller structure with low RPD looks to be more adequate. Further, maximizing gas holdup in the structures with high RPD is advantageous. The effects of impeller speed, gas superficial velocity, and rheology on the volumetric mass transfer coefficient were examined.CONCLUSIONThe volumetric mass transfer coefficient increased with an increase in impeller speed, gas superficial velocity, and power consumption per unit volume and decreased as rheology increased. The averaged kLa for each multiple‐impeller was correlated well with the specific gassed power consumption and gas superficial velocity. © 2024 Society of Chemical Industry (SCI).