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The design of vacuum systems for technological installations poses a formidable challenge, necessitating the use of mathematical modeling and computational tools. The application of modeling programs of chemical-technology systems allows the significant reduction in design time, facilitates the analysis of more variants of arrangement of the elements of the system, and also allows analysis of the influence of the elements of the system on each other. This study aims to develop a methodology for coupled modeling of intricate chemical-technology systems operating under vacuum conditions and to employ it in the design of practical industrial processes. The subject of this investigation is the vacuum-generation system in an amine mixture separation unit. The system consists of two series-connected Rust-type vacuum pumps and a forevacuum stage—a liquid ring vacuum pump. The coupling of the properties of the technological object and the vacuum-generation system implies coordination of their main characteristics, which are the main parameters describing the operating conditions of these units as a whole. To determine the intermediate pressures and equipment sizing, a computational model of the Rust-type vacuum pump is meticulously developed within the Aspen HYSYS V12 software suite, leveraging custom modules. The computed inlet pressures are subsequently incorporated via a purpose-built external-control program. Following calculations based on the chosen inlet pressures, the appropriate main and ancillary equipment are selected, while the overall system performance is meticulously assessed depending on the inlet pressures. The proposed configuration of the vacuum system promises to eliminate the formation of a chemically contaminated condensate, reduce circulating water consumption by a significant factor of 11, and concurrently reduce CO 2 emissions by an impressive 66%.

Rotor structure has a great influence on the gas backflow in a screw vacuum pump. The characteristics of the gas main flow along the spiral groove of the screw rotor and the gas reverse flow along the tooth-shaped, tooth side, radial, and circumferential clearances are investigated. A new mathematical model of the pumping flow and backflow involved in a flow balance model is proposed to investigate the actions of the shearing force and pressure difference force. The calculated backflow is verified by comparing the experimental measured results. The relationships of the structural parameters of the screw rotor are established. The effects of the rotor parameters, such as pitch, diameter, and compression ratio, on backflow are revealed. The results show that the rotor diameter and compression ratio remain constant and that the influence of pitch on the backflow is slightly weak, with backflow variations of less than 3%, whereas the pitch, rotor length, and compression ratio are constant and the rotor addendum diameter is directly proportional to the backflow. The addendum diameter of rotor #4 is the largest, and its backflow is about 1.5 times larger than that of rotor #1. When the rotor radial sizes and the pitch of the suction end are constant, the compression ratio is inversely proportional to the backflow in the low-pressure region and proportional to the backflow in the high-pressure regions. Therefore, for a vacuum pump operating in low-pressure areas, the use of the compression ratio of 2.2 or higher is favorable for the reduction in backflow.

To promote the development and application of the liquid–gas jet pump (LGJP), the research status of its design theory, internal flow mechanism, structural optimization and practical application are reviewed. The development history of the LGJP is briefly reviewed, the latest research and application progress of the LGJP is introduced, and the pulse-type of LGJP, especially the centrifugal jet vacuum pump (CJVP), is emphatically discussed. The research and development direction of the LGJP is analyzed and proposed: CFD will be more deeply applied to the mechanism research and performance improvement of the LGJP; the diversity and heterogeneity of the fluid medium and its influence on the internal flow mechanism are the research highlights of the LGJP; it is urgent to study the gas–liquid two-phase flow and pumping mechanism inside the pulsed liquid–gas jet pump (PLGJP), especially the CJVP.

A vacuum pump mainly consists of intermeshing screw rotors, which apply a cycloid profile to enhance the operating performance. However, it yields a concave rotor profile, increases the machining difficulty, and requires precision accuracy in the manufacturing process. This study proposes an analytical design of a particular whirling cutter and the rotor cutting method considering double tilt angles and assembly offset setting. The cutting simulation is demonstrated in analytical methods and virtual machining for various vacuum pump screw rotors. The analytical cutting result indicates that the overall lengthwise rotor profile deviation is identical. Besides, the virtual machining result indicates that the tooth surface topology is smooth and uniform, and the maximum profile deviation is still much more undersized than the grinding allowance. Moreover, the proposed method is still reliable for various vacuum pump rotors of Kashiyama type, Quimby type, Hanbell Precise Machinery P series, and Hanbell Precise Machinery P series with clearance design, where their delta deviations consistently tinier than 0.1 mm. Finally, it verifies that the proposed analytical design of the whirling cutter design, utilization of double tilt angles, and assembly offset setting are reliable for various vacuum pump rotors applying whirling milling machining.

In this paper, the experimental validation of an innovative clutch based on magnetorheological fluids (MRFs) excited by permanent magnets is described. The device, used in automotive applications to engage and disengage the vacuum pump, is tested using a standardized Worldwide harmonized Light-duty Test Cycle (WLTC). A test bench is built, and the system is observed in its operation for one hour, considering two consecutive WLTCs. The temperature increase slightly impacts the clutch’s behavior; in particular, the on-state performance of the device, mainly determined by the magnetic field-induced torque, remains largely unaffected by the temperature increase. The results showed that the performance of the proposed MRF-based device is only marginally affected by the phenomena that take place during the actual operation (e.g., temperature increase, shaft slip), confirming the effectiveness of the design.

Cross-section profile of rotor takes a great effect on the performance of dry-screw vacuum pump. A novel smooth rotor profile consisting of eight segments of curves, including arcs and conjugate correction curves is proposed. Advantages are that it can be used to solve the unsmooth connection and no meshing clearance in traditional profile. The meshing model for new profile can directly generate stable addendum clearance, tooth clearance, tooth side clearance, and radial clearance. The influences of the epicycloid rotation angle, arc radius and involute offset distance of the conjugate correction curve on the clearances are studied according to established theoretical model. And transient flow field of vacuum pump is analyzed by using the commercial software Ansys-Fluent®. Compared to traditional screw vacuum pump, the results shows that pressure in inlet and pump cavity is lower, and maximum pumping speed is higher, indicating that the proposed design is superior.

Traditional vacuum system designs often rely on a 100% reserve, lacking precision for accurate petrochemical computations under vacuum. This study addresses this gap by proposing an innovative modeling methodology through the deconstruction of a typical vacuum-enabled process. Emphasizing non-prescriptive pressure assignment, the approach ensures optimal alignment within the vacuum system. Utilizing process simulation software, each component was systematically evaluated following a proposed algorithm. The methodology was applied to simulate vacuum-driven separation in phenol and acetone production. Quantifying the vacuum system’s load involved constructing mathematical models in Unisim Design R451 to determine the mixture’s volume flow rate entering the vacuum pump. A standard-sized vacuum pump was then selected with a 40% performance margin. Post-reconstruction, the outcomes revealed a 22.5 mm Hg suction pressure within the liquid-ring vacuum pump, validating the efficacy of the devised design at a designated residual pressure of 40 mm Hg. This study enhances precision in vacuum system design, offering insights that are applicable to diverse petrochemical processes.

Accurate temperature prediction is vital for the canned permanent magnet synchronous motor (CPMSM) used in the vacuum pump, as it experiences severe heating. In this paper, a novel motor temperature calculation method is proposed, which takes into account the temperature impact on the heat transfer capacity. In contrast to existing electromagnetic-thermal coupled calculation methods, which solely address the temperature effect on the motor electromagnetic field, the proposed method comprehensively considers its impact on motor losses, permanent magnet magnetic properties, thermal conductivity, and heat dissipation ability of motor components, resulting in a motor temperature simulation that closely resembles the actual physical process. To verify the reliability of the proposed temperature calculation method, a 1.5 kW CPMSM was chosen as the research subject. The method was used to analyze the temperature distribution characteristics of the motor and assess the impact of ambient temperature on motor temperature rise. Furthermore, a prototype was fabricated, and an experimental platform was established to test the motor temperature. The results demonstrate good agreement between the calculated results obtained using the proposed method and the experimental data. This research not only provides a theoretical foundation for optimizing the design of the CPMSM but also provides valuable insights into its operational safety and reliability.

Data-driven health diagnosis methods based on machine learning have been receiving a lot of attention with the hope that they can open a new era for mechanical researchers and engineers. Machine learning algorithms including deep learning can show insights or state trends through complicated electro-mechanical sensor signals, but it is difficult for machine learning algorithms to go beyond the given data boundaries and to generalize their inferring rules from one case to the other. Researchers have even artificially damaged common mechanical parts in their experiments to collect fault signals for machine learning training. Creating and gathering the sensor signals covering a variety of machine status may be time-consuming or impossible in reality. Anomaly detection for dry vacuum pumps started from the recognition that the artificially induced fault signals may not reflect the natural malfunctioning state of the pumps. Anomaly detection algorithms use only normal data for training, so abnormal state data is not necessarily required. In this research several anomaly detection algorithms were tested and compared with time-domain input features and frequency-domain input features when acceleration signals were injected in for training. A long short-term memory based autoencoder (LSTM-autoencoder) scheme with discrete wavelet transformed (DWT) input signals was chosen for the finalist due to its superior capability capturing the nature of normal state characteristics. The output of LSTM-autoencoder’s loss could be used as an indicator of the machine’s health deterioration. Furthermore, we successfully demonstrated that the developed algorithm worked well on low-cost Internet of Things devices such as Raspberry Pi 4 and Arduino Mega 2560 boards for real-time monitoring.

The purpose of this study was to analyze the functioning of the vacuum distillation unit of a mini-refinery and to develop recommendations for improving the vacuum overhead system with the aim to reduce the cost of creating and maintaining a vacuum in the fuel oil separation column. A calculation model of the vacuum unit was developed in the Unisim Design R451 software package, which was identified by comparing the calculated data with the data from an industrial study for two operating modes of the installation. Replacing the existing steam-ejector pump with a liquid-ring vacuum pump was proposed. A numerical experiment was carried out on the developed model, the purpose of which was to determine the “bottlenecks” of the scheme. The peculiarity of the experiment was that the vacuum column and the vacuum overhead system were considered as a single whole. As a result, it was determined that the “bottleneck” is the condenser, which was proposed to be replaced. During the technical and economic analysis, two possible vacuum overhead system schemes were considered; according to the results, it was determined that the vacuum overhead system scheme based on a liquid-ring vacuum pump will help reduce operating costs by 78%.