Cryogenic Process Research Articles

Conceptual assessment of sustainable methane production from oxycombustion CO2 capture in waste-to-energy power plants

The worldwide deployment of renewable energy is growing exponentially. However, its intermittency limits its impact on the yearly energy contribution to the grid. Thus, coal remains the largest source of electricity generation in the world. Developing negative emissions technologies, such as Bioenergy with Carbon Capture and Utilization (BECCU), is a promising pathway. This study focuses on integrating waste biomass oxycombustion and a power-to-methane system. A proton exchange membrane electrolysis driven by photovoltaic solar energy is considered to produce hydrogen and oxygen, which is used for oxy-waste combustion in a sub-critical steam power cycle. Depending on the operation strategy, a certain amount of additional O2 would be required, produced by a cryogenic distillation air separation process. At the exit of the boiler, the almost pure CO2 stream is further purified, compressed, and sent to the methanation reactor. A quasi-stationary model of the entire plant is developed to simulate different operation conditions and assess the integration efficiency. The results show an excellent integration of the whole plant, with a yearly average efficiency penalty associated with the CO2 avoided of 6 % points. Since waste biomass is used as fuel, the system provides −610 kg CO2/MWh emissions compared to biomass plants without CO2 capture. Results from a yearly detailed techno-economic analysis show an average levelized cost of electricity of 199.56 €/MWh and an average green methane production cost of around 110.12 €/MWh. These yearly results involve a CO2 capture cost of about 65.66 €/ton CO2, which justify the potential interest in the proposed system for new and retrofitted biomass power plants.

Coupling chemical looping air separation with the Allam cycle – A thermodynamic analysis

The Allam cycle is a class of oxy-fuel combustion power cycles using supercritical CO2 (s-CO2) as the thermal fluid to achieve power generation with inherent capture of CO2. Compared to other conventional CO2 capture techniques, the Allam cycle stands out owing to its high fuel-to-electricity conversion efficiency (55–59%), the elimination of the Rankine cycle and reduced physical footprint. A key source of energy penalty of Allam cycle comes from the air separation unit (ASU), which supplies pure oxygen via an energy intensive cryogenic process. This paper presents a thermodynamic analysis of a novel supercritical CO2-based power generation scheme, in which a natural gas fuelled Allam cycle is integrated with a chemical looping air separation (CLAS) system, which supplies oxygen to the combustor. The modelling results show that the Allam-chemical looping air separation (Allam-CLAS) process can achieve 56.04% net electrical efficiency with a 100% CO2 capture rate, when a Co3O4-based oxygen carrier is used. This is 6% higher than the Allam cycle coupled to a cryogenic ASU. The exergetic efficiency of the Allam-CLAS system driven by the Co3O4-CoO redox cycle is 57.13%, also more favourable than a conventional Allam-ASU system (with reported exergetic efficiency of 53.4%). This newly proposed Allam-CLAS power cycle presents a highly efficient, and simple solution to generate zero-carbon electricity from natural gas.

Advanced natural gas liquefaction and regasification processes: Liquefied natural gas supply chain with cryogenic carbon capture and storage

Natural gas combined cycle power plants generate substantial amounts of CO2. Also, since natural gas is produced in limited sites, the liquefied natural gas (LNG) supply chain consumes considerable energy in transporting natural gas overwide. Herein, advanced natural gas liquefaction and regasification processes using an LNG supply chain with cryogenic CO2 capture and storage (CCS) are proposed using Aspen Plus® V11. This solves three significant problems associated with conventional LNG supply chains. First, through the utilization of LNG cold energy, the cryogenic CCS process reduces the efficiency penalty of power generation from 14.34 to 4.45%. Second, solid CO2 from cryogenic CCS is used as an additional cold source in the natural gas liquefaction process by conveying it to the liquefaction site via the returning LNG ship. As a result, the power consumption in the refrigerant cycle is reduced by up to 67.17% than single mixed refrigerant (SMR) process. Finally, the LNG supply chain with cryogenic CCS minimizes the sustained energy waste between the natural gas liquefaction and regasification stages owing to the geographical separation. LNG cold energy from the regasification stage is utilized in the form of solid CO2 in the CCS and liquefaction stages. Consequently, the exergy efficiency in the overall LNG supply chain increases from 18.18 to 46.39%. The findings of this study can potentially provide environmentally friendly design guidelines for various LNG processes that use LNG cold energy in CCS and natural gas liquefaction.

On the crystallization of solid formers during liquefaction of gases

Besides well-known technologies for the liquefaction of air components (N2, Ar, and O2) that of CH4, H2, and CO2 has recently caught attention for the energy transition and climate change targets. Gases undergoing cryogenic processes (cooling, liquefaction, cryo-compression) can contain a certain number of impurities, thus one challenge encountered in liquefaction is the solidification of heavy compounds present in the feed. In dealing with the crystallization risk of solid formers during liquefaction, attention is nowadays addressed to their solubility limits in the liquefied gas at the lowest temperature of the process, because solubility is known to decrease for decreasing temperatures. These limits are then used for tailoring the purification steps upstream the liquefaction train or modifying the operative conditions of the plant to avoid solid formation. In this work, the modeling and the analysis of the available data of several binary mixtures (like H2+N2, N2+CO2, CH4+CO2, and CO2+nC10H22) allow drawing insights about the thermodynamic behavior of such mixtures at low temperatures, showing that the lowest solubility limits are not always encountered at the lowest temperature, and this may have an impact on the design of industrial liquefaction processes. According to the liquefaction pressure, the first risk of solidification of the heaviest component could indeed be related to the deposition from the vapor phase rather than the solidification from the liquid phase. As a matter of fact, solubility limits of a solid former could be lower in a warmer gaseous/supercritical solvent than in a colder liquid solvent, thus solid formation could occur at temperatures that are up to tens of degrees higher than the final liquefaction temperature. Consequently, front-end purification units reducing the content of solid formers in the feed below their solubility limits in the liquefied gas could not be sufficient to completely avoid the risk of crystallization as temperature decreases.

Hydrogen Purification through a Membrane–Cryogenic Integrated Process: A 3 E’s (Energy, Exergy, and Economic) Assessment

Hydrogen (H2) is known for its clean energy characteristics. Its separation and purification to produce high-purity H2 is becoming essential to promoting a H2 economy. There are several technologies, such as pressure swing adsorption, membrane, and cryogenic, which can be adopted to produce high-purity H2; however, each standalone technology has its own pros and cons. Unlike standalone technology, the integration of technologies has shown significant potential for achieving high purity with a high recovery. In this study, a membrane–cryogenic process was integrated to separate H2 via the desublimation of carbon dioxide. The proposed process was designed, simulated, and optimized in Aspen Hysys. The results showed that the H2 was separated with a 99.99% purity. The energy analysis revealed a net-specific energy consumption of 2.37 kWh/kg. The exergy analysis showed that the membranes and multi-stream heat exchangers were major contributors to the exergy destruction. Furthermore, the calculated total capital investment of the proposed process was 816.2 m$. This proposed process could be beneficial for the development of a H2 economy.

Enriching the Bioactive Components and Antioxidant Capacity of Concentrated Lime Juices Prepared by Cryogenic and Vacuum Processes

Lime juice is rich in bioactive components and exerts a wide range of therapeutic effects, especially antioxidant activity. Freeze concentration is considered an essential method to maintain the nutritional values and bioactives of fruit juices. This study aimed to compare the ability in enriching ascorbic acid, total phenolic compounds, and major flavonoids and the antioxidant activity (DPPH) of concentrated lime juices prepared by vacuum and freeze-concentrations. The ascorbic acid in the juices was analyzed using the HPLC-PDA method. The total phenolic content and DPPH inhibition ability were measured by the colorimetric method. The polyphenol profiles of two lime varieties (C. latifolia and C. limonia) were qualitatively analyzed using LC-TOF MS/MS; then, the major juices’ flavonoids were analyzed by HPLC-PDA against/based on commercial standards. The results showed that C. latifolia was superior to C. limonia in ascorbic acid, TPC, major flavonoids, and antioxidants. C. latifolia was also more diverse than C. limonia in its polyphenol profile through the identified compounds (18 vs. 15). Freeze-concentrated lime juices were significantly higher than the vacuum-concentrated counterparts in ascorbic acid (mean difference from 9.41 to 22.01 mg, p < 0.01), and TPC (from 60.76 to 149.88 mgGAE). The quantification of major flavonoids showed that the freeze-concentrated lime juices retained high levels of hesperidin, eriocitrin, and rutin (p < 0.01) whereas the vacuum concentration preserved higher ones in diosmin and naringin (p < 0.01). The freeze-concentrated lime juice was significantly higher than vacuum-concentrated lime juices in the DPPH scavenging activity by at least 15% (p < 0.01). Overall, freeze concentration enriched bioactive compounds in lime juices almost threefold and improved antioxidants at least twofold. Thus, freeze concentration is promising for the industry in producing high-quality lime juice to preserve its thermal liable bioactive component.

THE ROLE OF SULFATE-REDUCING BACTERIA IN BIOMONITORING OF RIVER ECOSYSTEMS

Biomonitoring is one of the important stages in the consistent study of the sustainable development of aquatic ecosystems and their biological diversity. Against the background of the global impact on the hydrosphere, there is a need to select priority indicators and methods for determining the environmental risk in case of pollution of river ecosystems. Newly arriving substances are involved in complex biogeochemical processes in the water column, migrate as part of suspensions, or settle to the bottom. During the freezing period, a special place is occupied by cryogenic biochemical processes occurring in ice. Microbiological studies of the Amur River near the city of Khabarovsk showed that the water quality diff ered signifi cantly in winter. In the under-ice water and ice sampled off the coast, a diff erent composition of organic matter (OM) has been recorded for many years. After the fl oods (2013, 2019), a high number of sulfate- reducing bacteria was recorded in individual ice layers, which aff ect the dynamics of the transformation of natural and anthropogenic substances. This is due to the fact that in the area of Khabarovsk, during the period of ice cover formation, humifi ed OM spreads along the left bank, coming from the Zeya and Bureya reservoirs during technological discharges of water and from the fl oodplain, and along the right bank – waters contaminated with OM, mainly anthropogenic character. Long-term studies of the potential activity of sulfate- reducing bacteria in the Amur and its channels (Amurskaya, Pemzenskaya) make it possible to predict the formation of hydrogen sulfi de zones and the likelihood of mercury methylation over a wide temperature range. The indicator of resistance of cryomicrobial communities to high concentrations of mercury can be used for a retrospective assessment of the environmental risk of mercury pollution of rivers during the freeze-up period.

HYDROCHEMISTRY OF THE ZEYA RESERVOIR IN HIGH-WATER YEARS

The results of studying the chemical composition of the waters of the Zeya reservoir in high-water years (2013, 2021) are presented. It is shown that a signifi cant infl ow of water into the reservoir during these years caused in its waters a uniform distribution of concentrations of dissolved substances in the water area and depth in the summer- autumn period and extremely uneven in winter. The maximum values of mineralization, concentrations of calcium, magnesium, bicarbonate and sulfate ions, ammonium nitrogen, organic substances and dissolved iron were established in winter in the estuarine areas of the Argi and Zey regions as a result of the infl uence of cryogenic processes and fl ooding of the marshes of the Upper Zey plain. In the dam and canyon parts of the reservoir in winter, there were no large diff erences in mineralization values (28,4–41,9 mg/dm3), low content of ammonium nitrogen (< 0,03 mg N/dm3), increased values of water color (62–87°), concentrations of dissolved iron (0,35–0,74 mg/dm3) and organic matter (10,0–13,3 mg O/dm3). An assumption is made about the receipt of large amounts of dissolved substances in the Amur River in winter due to increased water consumption of the Zeyskaya HPP

Optimization of Energy Consumption of a Synthetic Ammonia Process

Ammonia can be produced from a wide range of raw materials such as coal, natural gas, coke and oil. Coal gasification is a process that converts biomass or fossil fuel-based carbonaceous materials into CO, H2 and CO2. A cryogenic air separation process was used to obtain oxygen from air because of high purity and high amount of oxygen, which will be used for coal gasification. For an ammonia synthesis process using pure oxygen gasification, the energy consumption of cryogenic air separation occupies a large proportion. The aim is to reduce energy consumed in the ammonia plant. The models of the process were developed with the aid of Aspen Plus. The energy consumption of the different processes was obtained through energy analysis, economic analysis and sensitivity analysis. From the three simulations, it can be seen that Simulation 3 produced oxygen with the highest purity of 0.979. From the energy analysis, the energy consumed on the total utilities in Simulation 1 was 5.626×1010 BTU/h with an energy savings of 1.55%, the energy consumed in Simulation 2 was 5.286×1010 BTU/h with an energy savings of 1.53% while the energy consumed on the total utilities in Simulation 3 was 1.425×109 BTU/h with an energy savings of 74.90%. Simulation 3 consumed the least energy. The economic analysis showed the total cost of each plant for a 10-year duration. Simulation 1 had a total operating cost of 42.083 billion USD/year, Simulation 2 had a total operating cost of 41.9615 billion USD/year and Simulation 3 had a total operating cost of 918.841 million USD/year. Therefore, Simulation 3 consumed the least cost of total operation. It can also be seen that the higher the energy consumption in a plant, the higher the total cost of the plant as Simulation 3 consumed the least energy, which justified that. Simulation 3 is the air separation plant that optimises the energy consumption, thereby reducing the energy consumed in the whole ammonia plant.

Impact of Cryogenic Treatment Process on the Performance of 51CrV4 Steel.

The working load on automotive components is continuously rising, and the mechanical performance requirements for component materials are rising along with the growth trend toward light weight and high dependability in automobiles. In this study, the response characteristics of 51CrV4 spring steel were taken to be its hardness, wear resistance, tensile strength, and impact toughness. Prior to tempering, cryogenic treatment was introduced. Through the Taguchi method and gray relational analysis, the ideal process parameters were discovered. The ideal process variables were the following: a cooling rate of 1 °C/min, a cryogenic temperature of -196 °C, a holding time of 24 h, and a cycle number of three. An analysis of variance revealed that the holding time had the greatest effect on the material properties, with an effect of 49.01%. The yield limit of 51CrV4 was increased by 14.95% and the tensile strength was increased by 15.39% with this group of processes, and the wear mass loss was reduced by 43.32%. The mechanical qualities had a thorough upgrade. Microscopic analysis revealed that cryogenic treatment resulted in refinement of the martensite structure and significant differences in orientation. Additionally, bainite precipitation occurred, exhibiting a fine needle-like distribution, which positively influenced impact toughness. Analysis of the impact fracture surface showed that cryogenic treatment led to an increase in dimple diameter and depth. Further analysis of the elements revealed that calcium (Ca) weakened the negative effect of sulfur (S) on 51CrV4 spring steel. The overall improvement in material properties provides guidance for practical production applications.

Ag+ anchored on sulfonic functionalized mesoporous silica towards efficient liquid phase Olefin-Paraffin separation

Separation of olefin-paraffin gas mixtures has attracted enormous research endeavors as a replacement of the currently used, energy-intensive cryogenic distillation process, while liquid phase olefin-paraffin separation has remained less exploited. The challenge lies in that the difference in physical properties between C6-C8 olefins and paraffins tend to diminish as C = C bond fraction becomes smaller when alkyl chain grows longer. On the other hand, satisfactory adsorption capacity for these bulky molecules requires the use of porous materials beyond microporosity, i.e., mesoporous materials with large pore volume and size, which, nonetheless, lack adsorption selectivity to guarantee satisfactory separation factors. Here, we demonstrate that functionalization of mesoporous silica MCM-41 surface by –COO-, -Ph-SO3- and -SO3- functional groups can be used to immobilize Ag+, which turns the otherwise unselective porous solid into an olefin selective molecular sieving material suitable for liquid phase binary mixture separations. The results underline that ionically anchored Ag+ with intact complexation orbitals outperform coordinatively immobilized Ag+ (on –NH2 or -SH groups), in terms of anti-leaching property, olefin separation factor, as well as recyclability. Small mesopore size can boost olefin adsorption selectivity as accommodated olefins compressed the available space for access of paraffins. Adsorption evaluation for binary C6 to C8 olefin-paraffin mixtures separations discloses that the total adsorption capacity declines, while the separation factor increases, with increasing molecule size.

The "domestication" of cold by the Russian population of Yakutia in the second half of the XIX – first half of the XX centuries.

The purpose of the article is to identify the main directions and reconstruct the practices of using cryogenic resources (cold, snow, ice, permafrost) and, in general, the "domestication" of cold by the Russian population of Yakutia during the mid XIX century and the twentieth century. The source base for writing the work was a set of disparate ethnographic information presented by published works and documents from the collections of the State Archive of the Irkutsk Region (Irkutsk), the Scientific Archive of the Siberian Branch of the Russian Academy of Sciences (Novosibirsk), the Archive of the Russian Academy of Sciences (Moscow) and its St. Petersburg branch. In addition, a number of information was obtained during the author's empirical research in a number of rural settlements of Yakutia during 2017-2023. The methodological basis for the preparation of the article is the principles laid down in cryosophy, which involve the study of the cold matter of the Earth through the prism of their role as an active element of the universe, as well as in the Cryoanthropology. Within the framework of the Cryoanthropology, the formation of the traditional culture of the indigenous ethnic groups of the Arctic and Subarctic is considered through the prism of the dominance of natural cold in the region, cryogenic processes and phenomena as fundamental, environmental factors. In this regard, the article shows the practices of the exploitation of cryogenic resources by the Russian population of Yakutia in cattle and horse breeding, agriculture, in ensuring the functioning of residential and outbuildings, organization of storage and preparation of food, etc. It is noted that they had certain specifics within various groups of Russian settlers caused by specific natural and geographical features of their areas of residence, as well as characteristics of interethnic ties. In this regard, differences between, for example, the Prilensky and Arctic groups of the Russian old-timers have been recorded. The key vectors of the "domestication" of cold by the Russian population of Yakutia are highlighted.

Energy analysis and optimization of heat integrated air separation column based on non-equilibrium stage model

A large scale of nitrogen and oxygen production has been through a cryogenic air separation process. This process takes place in a distillation column at excessive energy consumption. The heat-integrated air separation column (HIASC) can save energy when utilizing minimum pressure while ensuring adequate heat distribution along the portion of the column. However, accurate prediction of thermodynamic and fluid properties requirement is critical for process optimization and potential energy saving. The nonequilibrium stage model is employed to gain insight into the thermodynamic properties. While examining the influence of these properties, essential process operating variables are optimized to save energy. The research result shows that more than 17% of energy is preservable in the HIASC.

4E analysis of the cryogenic CO2 separation process integrated with waste heat recovery

Carbon dioxide capture, utilization, and storage (CCUS) is an attractive method to reduce carbon dioxide (CO2) emissions originating from fossil fuels burned from large single-point sources. CO2 separation from a CO2-laden gas stream is the first stage of CCUS. In this investigation, a cryogenic distillation-based CO2 separation process (CCSP) is developed. CCSP is modified to utilize waste heat obtained in the process for reducing the energy consumption of CO2 separation. Two modifications are carried out in the process which include (i) heat integration (HI) with CCSP (CCSP + HI) of the reboiler with the heat from hot streams available in the process and further, (ii) energy recovery by using the organic Rankine cycle (ORC) operating between gas compressor temperature and ambient temperature (CCSP + HI + ORC). The parametric and 4 E (energy, exergy, economic, and environmental) analysis results obtained for the CCSP + HI, CCSP + ORC, and CCSP + HI + ORC processes are compared with those of CCSP. The net electrical energy required to operate the compressor for CCSP is 2.7%, 7%, and 21.8% higher than that for CCSP + HI, CCSP + ORC, and CCSP + HI + ORC, respectively.

Highly-selective xenon–krypton separation using hydrate-based technology

Xenon (Xe) and krypton (Kr) are used in many important industries such as lighting, lasers, double glazing for insulation, and medicine. As Xe and Kr are found in extremely low concentrations in the atmosphere, only small quantities of the mixture of these gases are obtained as byproducts from air separation processes. As the further separation of Kr from Xe is achieved via a costly energy-intensive cryogenic distillation method, the development of a new cost-effective approach for Xe–Kr separation is essential. In this study, we demonstrated that clathrate hydrates can be used as a promising Xe trap to separate a Xe–Kr mixture and produce Kr-rich vapors. The Xe and Kr guest distributions in mixed clathrate hydrates were experimentally identified using powder X-ray diffraction, solid-state 129Xe NMR spectroscopy, and gas chromatography. The mixed Xe + Kr hydrates have a Pm3¯n structure, termed structure I (sI), regardless of the concentration of Xe in the feed vapor in the range of 3% to 100%, and the sI hydrate selectively captures Xe from the feed mixture. The phase equilibria of the mixed Xe + Kr hydrates were also investigated, and it was confirmed that the hydrate-based Xe–Kr separation process requires milder temperature conditions than the cryogenic distillation process. Overall, the findings in this work suggest that the hydrate-based Xe–Kr separation process is an excellent alternative to the energy-intensive cryogenic distillation method.

Efficient recovery of C2+ alkanes from natural gas using porous ZIF-8/iso-hexadecane slurry on laboratory and pilot-scale

The efficient recovery of C2+ alkanes from natural gas is of great significance since the C2+ alkanes are the essential petrochemical raw material. This paper presents the novel absorption-adsorption hybrid method to recover the C2+ alkanes components from natural gas using a flowable zeolitic imidazolate framework-8 (ZIF-8)/iso-hexadecane slurry. The ZIF-8 particles have an excellent dispersion in the iso-hexadecane solvent. The sorption capacity for C2H6 and C3H8 in the slurry is significantly higher than that for CH4. Moreover, in competitive adsorption, the slurry showed a significant advantage for C2H6 and C3H8 over CH4. In the experiments of recovering C2+ alkanes from natural gas, the recovery ratio can reach a staggering 91.59%. Besides, in the regeneration tests, 97.79% of the sorption capacity for C2H6 can be recovered by vacuuming without temperature swings, and the characteristic structure of the recycled ZIF-8 remains intact. More encouragingly, a continuous pilot separation plant was established, and the test results show that the recovery ratio for C2+ alkanes can reach 86.75%. The excellent selective recovery performance is comparable to the mature cryogenic separation process. To our knowledge, this is the first time to apply metal–organic frameworks (MOFs) to separate natural gas on pilot-scale. This work has thus furthered the industrial application of MOFs in gas separation.

Effect of cryogenic laser surface modification on the microstructure evolution and corrosion resistance of accident-tolerant FeCrAl alloys

Accident-tolerant FeCrAl alloys require a thinner cladding wall than zirconium cladding to overcome the extra neutron loss, thus requiring enhanced corrosion resistance. Surface treatment was used in this study to address this issue via cryogenic laser surface modification. A finite element model based on heat-transfer theory was raised to reveal the temperature field change during cryogenic laser treatment. The relationship between the laser processing parameters and surface morphology was studied with various characterizations to better understand the process mechanism and verify the correctness of the model. Hydrothermal corrosion test was proceeded in an autoclave at 290 °C and 7.5 MPa for 150 h to examine the enhancing corrosion resistance. STEM observations were used to study the microstructure evolution by cryogenic laser processing and corrosion. Electrochemical tests were performed to analyze the relationship between processing parameters and corrosion resistance before and after corrosion. The oxide film thickness and corrosion rate of the cryogenic laser-modified sample were 66 % and 80 % smaller than the as-received sample. The enhanced corrosion resistance was attributed to the microcrystalline layer and the thin duplex passive film that formed during the cryogenic laser process.

The soil–cryogenic complex: Evidence of late Pleistocene–Holocene coevolution of permafrost and cryosols at the Kolyma Lowland

AbstractOne of the most important problems of cryopedology is the interaction of pedogenic processes with the processes that form the structure of the uppermost layers of the near‐surface permafrost. The thickness, structure, spatial variability, and other features are responsible for the reaction of the soil‐permafrost system to the bioclimatic fluctuations as well as the contemporary anthropogenic pressure. Together the soil profile and the upper layers of permafrost form the natural body of the “soil–cryogenic complex,” which is the result of simultaneous late Pleistocene–Holocene soil and permafrost coevolution. Pedogenic and cryogenic processes together form organic‐accumulative horizons above the permafrost table that have often been described in the profiles of Cryosols in different regions of Arctic. The multiannual dynamics of summer thawing depth determine the involvement of the material of these shielding horizons into the zone of active modern pedogenesis or its exclusion from it in case of their frozen state. Soil surface microrelief, complexity of the vegetation, and spatial differences of thermal properties of the suprapermafrost soil horizons and the transient layer of permafrost are responsible for the complicated pattern of permafrost table microrelief. Thus, the long‐term study of cryogenic soils that are developed on the close underlying permafrost provides improved understanding of the natural‐historical body—soil‐cryogenic complex.

Energy consumption, mechanical and metallographic properties of cryogenically treated tool steels

Abstract This article examines energy consumption, microstructure, mechanical properties, and the change in the wear amount during the machining of GGG-42 cast iron material with two types of guide cutting tool produced by powder metallurgy and casting method The tap. tool samples used as cutting tool material were first subjected to the traditional hardening process and then to two different cryogenic treatments (24–16 h) at −90°C. The internal structures of the guide samples obtained from conventional heat treatment and cryogenic treatment were examined with an optical microscope and Scanning Electron Microscope. The hardness changes were checked with Vickers measurement method. The wear amount forming after the threading process was measured with CLEMEX program in a light microscope. In addition, by measuring the current amount drawn during the machining of the cast iron with guide cutter tools, instantaneous power consumption during cutting and power consumption during chip removal were calculated. The application of heat treatment and cryogenic process increased the hardness of the guides. Moreover, the power consumption during the chip removal was also seen to increase. This can be commented that cutting tools produced with powder metallurgy perform better than the cutting tools produced via casting and 30% energy saving.

Research on liquid nitrogen cryogenic milling of 11Cr-3Co-3W martensitic heat-resistant steel

PurposeWhen processing 11Cr-3Co-3W martensitic heat-resistant steel, the traditional pouring cooling method often appears large cutting force, high cutting temperature, serious tool wear and poor surface quality. This paper aims to use new cooling methods for processing this problem.Design/methodology/approachDifferent performance indicators such as cutting force, tool wear and surface quality were measured and analysed under different continuous milling times. The relationship between liquid nitrogen flow and cutting force and surface roughness was analysed and measured.FindingsThe results show that with the increase of liquid nitrogen flow, the cutting force decreases, especially the Fx component, which decreases by 10%. When the liquid nitrogen flow reaches 8 L/min, the effect of increasing the liquid nitrogen flow on reducing the cutting force becomes smaller. The cutting force reduced by up to 15%, and the tool life increased up to 20% using liquid nitrogen cryogenic cooling than in cutting liquids cooling. When minimal quantities of lubricant (MQL) was added, the cutting force was reduced by 23%, and the tool life increased by 25%. When the cutting speed increases from 100 m/min to 250 m/min, the cutting force with cutting liquid cooling does not change significantly while the cutting force with liquid nitrogen cooling decreases with the cutting speed increasing. It shows that liquid nitrogen cooling is more suitable for high-speed machining. After the cutting length reaches 66 m, the surface roughness of the workpiece using liquid nitrogen cooling method larger than that of the cutting liquid cooling method. When MQL is added into liquid nitrogen, the lubrication performance is improved, and the surface roughness of the workpiece is reduced about 8%.Originality/valueMany studies had focused on the improvement of tool life and surface quality by different cooling methods, or on the injection process and chip mechanism. However, there are few relevant studies on the variation of cooling and lubrication properties with the change of cutting length in liquid nitrogen cryogenic processing. In this research, different performance indicators such as cutting force, tool wear and surface quality were measured and analysed under different continuous milling times. The relationship between liquid nitrogen flow and cutting force and surface roughness was analysed and measured.Peer reviewThe peer review history for this article is available at: https://publons.com/publon/10.1108/ILT-03-2023-0053/