Search Results (136)

Sanicro 25 (X7NiCrWCuCoNb25-23-3-3-2) steel is specifically designed for use in superheater components within the latest generation of conventional power plants. These power plants operate under conditions often referred to as super-ultra-supercritical, with steam parameters that can reach up to 30 MPa and temperatures of 653 °C for fresh steam and 672 °C for reheated steam. While last-generation supercritical power plants still rely on fossil fuels, they represent a significant step forward in more sustainable energy production. The most sophisticated facilities of this kind can achieve thermodynamic efficiencies exceeding 47%. This study aimed to conduct a detailed analysis of the initial precipitation processes occurring in Sanicro 25 steel within the temperature range of 700–900 °C. The temperature of 700 °C corresponds to the operational conditions of this material, particularly in secondary steam superheaters in thermal power plants that operate under ultra-supercritical parameters. Understanding precipitation processes is crucial for optimizing mechanical performance, particularly in terms of long-term strength and creep resistance. To accurately assess the microstructural changes that occur during the early stages of service, a digital twin approach was employed, which included CALPHAD simulations and experimental heat treatments. Experimental annealing tests were conducted in air within the temperature range of 700–900 °C. Precipitation behavior was simulated using the Thermo-Calc 2025a with Dictra software package. The results from Prisma simulations correlated well with the experimental data related to the kinetics of phase transformations; however, it was noted that the predicted sizes of the precipitates were generally smaller than those observed in experiments. Additionally, computational limitations were encountered during some simulations due to the complexity arising from the numerous alloying elements present in Sanicro 25 steel. The microstructural evolution was investigated using various methods, including light microscopy (LM), scanning electron microscopy (SEM), and transmission electron microscopy (TEM). Full article

Heuristic optimization is used to find sustainable cogeneration steam power plants with steam reheat and supercritical main steam parameters. Design solutions are analyzed for steam consumer (SC) pressures of 3.6 and 40 bar and a heat flow rate of 40% of the fuel heat flow rate. The objective functions consisted in simultaneous maximization of global and exergetic efficiencies, power-to-heat ratio in full cogeneration mode, and specific investment minimization. For 3.6 bar, the indicators improve with the increase in the ratio between reheating and main steam pressure. The increase in SC pressure worsens the performance indicators. For an SC steam pressure of 40 bar and 9 feed water preheaters, the ratio between reheating and main steam pressure should be over 0.186 for maximum exergetic efficiency and between 0.10 and 0.16 for maximizing both global efficiency and power-to-heat ratio in full cogeneration mode. The average global efficiency for an SC requiring steam at 3.6 bar is 4.4 percentage points higher than in the case with 40 bar, the average specific investment being 10% lower. The Pareto solutions found in this study are useful in the design of sustainable cogeneration supercritical power plants. Full article

Gasification of municipal solid waste and other biogenic residues (e.g., biomass and biowaste) is increasingly recognized as a promising thermochemical pathway for converting non-recyclable fractions into valuable energy carriers, with applications in electricity generation, district heating, hydrogen production, and synthetic fuels. This paper provides a comprehensive analysis of major gasification technologies, including fixed bed, fluidized bed, entrained flow, plasma, supercritical water, microwave-assisted, high-temperature steam, and rotary kiln systems. Key aspects such as feedstock compatibility, operating parameters, technology readiness level, and integration within circular economy frameworks are critically evaluated. A comparative assessment of incineration and pyrolysis highlights the environmental and energetic advantages of gasification. The valorization pathways for main product (syngas) and by-products (syngas, ash, tar, and biochar) are also explored, emphasizing their reuse in environmental, agricultural, and industrial applications. Despite progress, large-scale adoption in Europe is constrained by economic, legislative, and technical barriers. Future research should prioritize scaling emerging systems, optimizing by-product recovery, and improving integration with carbon capture and circular energy infrastructures. Supported by recent European policy frameworks, gasification is positioned to play a key role in sustainable waste-to-energy strategies, biomass valorization, and the transition to a low-emission economy. Full article

Carbon capture, utilization, and storage (CCUS) is a key technology for decarbonizing existing or newly designed fossil fuel power plants, which in the short to medium term remains essential to offset the variability of nonprogrammable renewable sources in power generation. In this paper, the authors focus on the CO₂ compression phase of CCUS systems, integrated with power plants, and propose, according to the technical literature, a plant layout aimed at minimizing energy consumption; then, they carry out the preliminary design of all compressors, identifying compact and efficient configurations. The case study concerns an advanced ultra-supercritical steam plant (RDK8 Rheinhafen-Dampfkraftwerk in Karlsruhe, Germany) with a nominal net thermal efficiency of 47.5% and an electrical output of 919 MW. The main results obtained can be summarized as follows. The overall compression in the IGC configuration requires only six stages and each compressor is single-stage, while in the inline configuration, ten stages are needed; the diameters in the IGC solution, also due to a higher rotational speed, are smaller, despite the in-line solution being multistage. An interesting further investigation could be related to modifications of the plant scheme, especially to test whether CO₂ liquefaction at an intermediate stage of compression could result in reductions in energy consumption, as well as even more compact design solutions. Full article

In the present study, the extraction of volatile terpenes from A. annua with supercritical CO₂ (sc-CO₂) was optimized by a full factorial design procedure and compared with conventional distillation. The influence of pressure (100–220 bar) and temperature (40–60 °C) on sc-CO₂ extraction was investigated to obtain extracts rich in the desired components while maintaining a high yield. Extraction yields (m/m) varied from 0.62% (130 bar/40 °C) to 1.92% (100 bar/60 °C). Monoterpenes were the most abundant constituents of the sc-CO₂ extracts, among which artemisia ketone (16.93–48.49%), camphor (3.29–18.44%) and 1,8-cineole (4.77–11.89%) dominated. Arteannuin B (3.98–10.03%) and β-selinene (1.05–7.42%) were the major sesquiterpenes. Differences were found between the terpene profiles of the sc-CO₂ extracts and the essential oils obtained by conventional hydrodistillation and steam distillation, as well as between the distilled essential oils. Our results demonstrate the optimal conditions for the rapid and effective supercritical extraction of certain monoterpenes and sesquiterpenes from A. annua, which have promising antimicrobial, antioxidant, antiviral, anti-inflammatory and antitumor properties. Full article

This article presents the results of an experimental investigation of silica deposition from depressurized supercritical steam. The case investigated is relevant for supercritical geothermal reservoirs with high temperature and pressure, where silica content is significant and deposition occurs rapidly upon depressurization. The purpose of the presented experiments is to accurately measure the deposited mass in two different areas in a flow tube and mathematically relate the measurement to particle formation behavior. In addition, SEM analysis permits valuable insight into the morphology of the scale formed under these conditions. The measured deposition is caused by silica solids formed when depressurizing supercritical fluids from around 350 bar and 500 °C by an isenthalpic valve to a state of superheated steam and pressures ranging from 60 to 150 bar. A test rig was designed, fabricated, and used for this purpose. The deposition mechanisms differ from silica particle formation in the water phase and the limited experimental research for the investigated conditions makes the gathered data highly interesting. The measured results are compared to validated models for deposition in straight pipes. The knowledge obtained on silica solidification and deposition can be used to optimize steam treatment of high-temperature pressurized geothermal sources for maximum power utilization by aiding in the development of advanced prediction tools for scaling and mineral extraction. Full article

Objectives: The immune-enhancing properties of steamed mature silkworm, known as HongJam (HJ), were investigated using human interleukin-2-independent Natural Killer 92 (NK92-MI) cells and a cyclophosphamide intraperitoneal injection-induced immunosuppressed mice model (CPA-IP). White Jade variety mature silkworm HJ (WJ-HJ) was used to prepare WJ-HJ supercritical fluid extracts (WJ-SCE) and WJ-HJ-supplemented feeds. Results: Treatment with WJ-SCE significantly enhanced proliferation, migration, and cytotoxicity of NK92-MI cells against various cancer cells while improving mitochondrial function and ATP production (p < 0.05). In CPA-IP mice, consumption of WJ-HJ-supplemented feeds restored immune function by improving body weight, immune organ indices, immunoglobulin levels, and blood cytokines. Splenocyte proliferation and cytotoxicity were significantly elevated in both saline intraperitoneal injection (Sal-IP) and CPA-IP groups with WJ-HJ supplementation, independent of mitogen activation (p < 0.05). Conclusions: These results suggest that WJ-HJ enhances immune modulation and immune surveillance functions of NK cells by improving mitochondrial and cytotoxic functions. WJ-HJ holds promise as a functional food for immune enhancement, pending clinical validation. Full article

Steam thermal power plants represent important energy production systems. Within the energy mix, these could allow flexible generation and the use of hybrid systems by integrating renewables. The optimum design solution and parameters allow higher energy efficiency and lower environmental impact. This paper analyzes single reheat supercritical steam power plants design solutions using a genetic heuristic algorithm. A multi-objective optimization was made to find the Pareto frontier that allows the maximization of the thermal cycle net efficiency and minimization of the specific investment in the power plant equipment. The Pareto population was split and analyzed depending on the total number of preheaters. The mean values and the standard deviations were found for the objective functions and main parameters. For the thermal cycle schemes with eight preheaters, the average optimal thermal cycle efficiency is (48.09 ± 0.16)%. Adding a preheater increases the average optimal thermal cycle efficiency by 0.64%, but also increases the average optimum specific investments by 7%. It emphasized the importance of choosing a proper ratio between the reheating and the main steam pressure. Schemes with eight and nine preheaters have an average optimum value of 0.178 ± 0.021 and 0.220 ± 0.011, respectively. The results comply with data from the literature. Full article

Lavender is one of the most appreciated aromatic plants, with high economic value in food, cosmetics, perfumery, and pharmaceutical industries. Lavender essential oil (LEO) is known to have demonstrative antimicrobial, antioxidant, therapeutic, flavor and fragrance properties. Conventional extraction methods, e.g., steam distillation (SD) and hydro-distillation (HD), have been traditionally employed to extract LEO. However, the low yield, high energy consumption, and long extraction time of conventional methods have prompted the introduction of novel extraction technologies. Some of these innovative approaches, such as ohmic-assisted, microwave-assisted, supercritical fluid, and subcritical water extraction approaches, are used as substitutes to conventional extraction methods. While other methods, e.g., sonication, pulsed electric field, and cold plasma, can be used as a pre-treatment that is preceded by conventional or emerging extraction technologies. These innovative approaches have a great significance in reducing the energy consumption, shortening the extraction time, and increasing the extraction yield and the quality of EOs. Therefore, they can be considered as sustainable extraction technologies. However, the scale-up of emerging technologies to an industrial level should also be investigated from the techno-economic points of view in future studies. Full article

The growing demand for plant-based protein and natural food ingredients has further fueled interest in exploring hemp seeds (Cannabis sativa L.) as a sustainable source of and nutrition. In addition to the content of proteins and healthy fats (linoleic acid and alpha-linolenic acid), hemp seeds are rich in phytochemical compounds, especially terpenoids, polyphenols, and phytosterols, which contribute to their bioactive properties. Scientific studies have shown that these compounds possess significant antioxidant, antimicrobial, and anti-inflammatory effects, making hemp seeds a promising ingredient for promoting health. Since THC (tetrahydrocannabinol) and CBD (cannabidiol) are found only in traces, hemp seeds can be used in food applications because the psychoactive effects associated with cannabis are avoided. Therefore, the present article reviews the scientific literature on traditional and modern extraction methods for obtaining active substances that meet food safety standards, enabling the transformation of conventional foods into functional foods that provide additional health benefits and promote a balanced and sustainable diet. Also, the identification methods of biologically active compounds extracted from hemp seeds and their bioactivity were evaluated. Mechanical pressing extraction, steam distillation, solvent-based methods (Soxhlet, maceration), and advanced techniques such as microwave-assisted and supercritical fluid extraction were evaluated. Identification methods such as high-performance liquid chromatography (HPLC) and mass spectrometry (MS) allowed for detailed chemical profiling of cannabinoids, terpenes, and phenolic substances. Optimizing extraction parameters, including solvent type, temperature, and time, is crucial for maximizing yield and purity, offering the potential for developing value-added foods with health benefits. Full article

Improvement of energy efficiency in technological processes at industrial enterprises is one of the key areas of energy saving. Reduction of energy costs required for the production of energy-intensive products can be achieved through the utilization of waste heat produced by high-temperature thermal furnace units. Generation of electric power based on the waste heat using power cycles with working fluids that are not conventional for large power engineering, may become a promising energy saving trend. In this paper, thermodynamic analysis and optimization of power cycles for the purposes of waste heat recovery are performed. The efficiency of combining several power cycles was also evaluated. It has been established that the combination of the Brayton recompression cycle on supercritical carbon dioxide with the organic Rankine cycle using R124 allows for greater electrical power than steam-power cycles with three pressure circuits under conditions where the gas temperature is in the range of 300–550 °C and the cooling temperature of is up to 80 °C. Additionally, when cooling gases with a high sulfur and moisture content to 150 °C, the combined cycle has greater electrical power at gas temperatures of 330 °C and above. At enterprises where the coolant has a high content of sulfur compounds or moisture and deep cooling of gases will lead to condensation, for example, at petrochemical and non-ferrous metallurgy enterprises, the use of combined cycles can ensure a utilization efficiency of up to 45%. Full article

Objectives: The unknown immune-enhancing effects of steamed mature silkworms (Bombyx mori L.), known as HongJam (HJ), were investigated. Methods: Supercritical fluid extracts from the White Jade variety of HJ (WJ-SCEs) were applied to in vitro RAW264.7 macrophages (RAWMs) and ex vivo bone marrow-derived macrophages (BMDMs). Results: WJ-SCE enhanced the proliferation and viability of both RAWMs and BMDMs. Supplementation with WJ-SCE significantly reduced the lipopolysaccharide (LPS)-induced expression of iNOS mRNA and protein, resulting in decreased nitric oxide (NO) production. Additionally, WJ-SCE lowered the mRNA and protein expression of COX-2 and reduced the levels of pro-inflammatory cytokines. The mitochondrial function, ATP levels, and reactive oxygen species levels in LPS-treated macrophages were restored following WJ-SCE treatment. WJ-SCE modulated LPS-Toll-like receptor-4 (TLR-4) signaling by reducing the levels of phosphorylated (p)-p38, p-ERK1/2, and p-p65. WJ-SCE also restored gene expression related to cytokines, chemokines, glucose transport, mitochondrial metabolism, and TLR-4 signaling, suggesting the inhibition of pro-inflammatory M1 macrophage polarization. Furthermore, WJ-SCE enhanced macrophage phagocytic and pinocytotic activity. Conclusions: WJ-SCE demonstrated anti-inflammatory effects by inhibiting LPS-induced M1 polarization in both macrophage types, potentially suppressing chronic inflammation while enhancing phagocytosis and pinocytosis. Full article

P92 steel is widely used in ultra-supercritical units due to its excellent high-temperature performance. This paper studies the microstructure of P92 steel steam pipes in three conditions: as-supplied, after 80,000 h of service at 67.06 MPa stress, and after 100,000 h of service at 80.28 MPa stress. After prolonged service, the P92 steel retains its martensitic structure, but the lath width increases and the dislocation density decreases. In addition to M₂₃C₆, MX, and Laves phases, Z phase was also observed among the precipitates. The results indicate that the sizes of M₂₃C₆ and Laves phases increase with the progression of creep life consumption, with the coarsening rate of Laves phase being significantly higher than that of M₂₃C₆. However, the coarsening of MX phase is not evident. Compared to the Laves phase, the formation of the Z phase requires a longer period of time. The precipitation of the Z phase consumes MX carbonitrides, and it has been observed that the Z phase precipitates from the MX phase, with the two phases exhibiting a coexisting state. Full article

Steam reforming is an effective method for improving heat sinks of hypersonic aircraft at high flight Mach numbers. However, unlike the industrial process of producing hydrogen with a high water content, the catalytic steam reforming mechanism for the regeneration cooling process of hydrocarbon fuels with a water content below 30% is still unclear. Catalytic steam reforming (CSR) and catalytic thermal cracking (CTC) reactions occur at low temperatures, with the main products being hydrogen and carbon oxides. Thermal cracking (TC) reactions occur at high temperatures, with the main products being alkanes and alkenes. The above reaction exists simultaneously in the regeneration cooling channel, which is referred to as partial catalytic steam reforming (PCSR). Based on the experimental measurement results, an improved neural network correction method was used to establish a four-step global reaction model for the PCSR of n-decane under low water conditions. The reliability of the four-step model was verified by combining the model with a numerical simulation program and comparing it with the experimental results obtained by electric heating hydrocarbon fuels with a pressure of 3 MPa and a water content of 5/10/15%. The experimental and predicted results using the developed kinetic model are consistent with an error of less than 5% in the decane conversion rate. The average absolute error between the fuel outlet temperature and total heat sink is less than 10%. Using the PCSR model to predict the heat transfer characteristics of mixed fuels with different water contents, the convective heat transfer coefficient is basically the same, and the Nu number is affected by the thermal conductivity coefficient, showing different patterns with changes in the water content. Full article

To investigate the mechanical properties and microstructure evolution of P92 steel during long-term service, the operated P92 main steam pipes from the first ultra-supercritical units in China were sectioned into samples representing various service durations and stresses (0# (as-received state, 1# (82,000 h, 67.3 MPa), 2# (85,000 h, 78.0 MPa), and 3# (100,000 h, 80.3 MPa)). Thereafter, a comprehensive assessment of their mechanical properties, including tensile strength, impact, hardness, and creep resistance, as well as a detailed microstructure analysis, was carried out. The effect of stress on the aging of material properties during operation is discussed. The results show that the circumferential stress caused by the increase in the internal steam pressure can significantly promote the creep life consumption of P92 steel, resulting in the degradation of mechanical properties and the expedited aging of the microstructure. The R_p0.2 and R_m of the P92 main steam pipe at room temperature and 605 °C decreased with the service time increase, reflecting the influence of stress in operation, which is expected to be used for the residual life evaluation of P92 steel. The relationship between the impact absorption energy (FATT50), Brinell hardness, and the operating time of P92 operating pipes is non-monotonic, indicating that these parameters are not sensitive indicators of material aging due to stress. The evaluation of performance degradation in P92 operating pipes due to stress-induced aging is not reliably discernible through optical metallography alone. To achieve a thorough assessment, the use of transmission electron microscopy (TEM) is essential. Full article