Improvement of the Liquefied Natural Gas Vapor Utilization System Using a Gas Ejector

The production, transportation, and storage of liquefied natural gas (LNG) is a promising area in the gas industry due to a number of the fuel’s advantages, such as its high energy intensity indicators, its reduced storage volume compared to natural gas in the gas-air state, and it ecological efficiency. However, LNG storage systems feature a number of disadvantages, among which is the boil-off gas (BOG) recovery from an LNG tank by flaring it or discharging it to the atmosphere. Previous attempts to boil-off gas recovery using compressors, in turn, feature such disadvantages as large capital investments and operating costs, as well as low reliability rates. The authors of this article suggest a technical solution to this problem that consists in using a gas ejector for boil-off gas recovery. Natural gas from a high-pressure gas pipeline is proposed as a working fluid entraining the boil-off gas. The implementation of this method was carried out according to the developed algorithm. The proposed technical solution reduced capital costs (by approximately 170 times), metal consumption (by approximately 100 times), and power consumption (by approximately 55 kW), and improved the reliability of the system compared to a compressor unit. The sample calculation of a gas ejector for the boil-off gas recovery from an LNG tank with a capacity of 300 m3 shows that the ejector makes it possible to increase the boil-off gas pressure in the system by up to 1.13 MPa, which makes it possible to not use the first-stage compressor unit for the compression of excess vapours.

Low-Cost Inventions and Patents

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DSP Processer-in-the-Loop Tests Based on Automatic Code Generation

The digital signal processing (DSP) processor-in-the-loop tests based on automatic code generation technology are studied. Firstly, the idea of model-based design is introduced, and the principle and method of embedded code automatic generation technology are analyzed by taking the automatic code generation of the DSP control algorithm for pulse width modulation (PWM) output as an example. Then, the control system model is established on MATLAB/Simulink. After verifying the model through simulation, the target board platform is established with DSP as the core processor, and the automatically generated code is tested by the processor-in-the-loop (PIL). The results show that the technology greatly shortens the development cycle of the project, improves the robustness and consistency of the control code, and can be widely used in the complex algorithm development process of the controller, from intelligent design and modeling to implementation.

Review on Study Methods for Reciprocally Enwrapping Surfaces

The processing of the piece surfaces involves the transformation of the blank into a piece, the defining characteristics of the surfaces (the form, dimensions, deviations, etc.), depending to a large extent on the parameters of the generated processes of the surfaces. Generating surfaces by enveloping represents a complex problem, this mode of generating being a constant concern of researchers due to its advantages. A very important issue is the cutting edge profiling of the future tool, which will generate the wanted profile of the piece. Throughout time, researchers have studied the problems of enveloping surfaces and stated theorems related to them, based on which practical solutions have been conceive to determine the generating and generated surfaces form. The paper presents an overview on study methods for reciprocally enwrapping surfaces, as well as methods for profiling tools for generating helical surfaces by the kinematic method and by the method of decomposing the helical movement. This review can represent a basis for future research articles and projects.

Estimation of the Tower Shape Effect on the Stress–Strain Behavior of Wind Turbines Operating under Offshore Boundary Conditions

The metal tower, or the pylon, is one of the most important elements in the construction of a wind turbine. It has the role of supporting the entire wind turbine, and it also allows access for inspection and conducting planned maintenance and repairs. Moreover, the tower ensures support for the structure and strengthens the whole assembly. It has a particularly important role, as it has to face very severe weather conditions. The present study aims to analyze the forces and moments resulting from the action of the wind on the tower of a wind turbine. Two important load cases are considered, namely, the load under operating conditions and the ultimate load under 50 year wind conditions. For this purpose, cylindrical and conical geometric shapes of the tower were chosen. These were analyzed under the action of both normal and extreme wind speeds. Then, the behavior of the two towers under the action of the wind speed for a location in the Black Sea was analyzed. Finally, in an attempt to make the structure more economical, the thickness of the shell was reduced.

Numerical Study on Plastic Strain Distributions and Mechanical Behaviour of a Tube under Bending

Tubular pipe structures have been used in various applications—domestic, aviation, marine, manufacturing and material testing. The applications of tubular pipes have been considered greatly in the installation of tubular pipes, marine risers and pipe bending. For the investigation of plastic strains and the mechanical behaviour of a tube under bending, considerations were made utilising an exponent model with assumptions on the plane strain. The bending moment, wall thickness effect, cross-sectional distribution, stresses during bending and neutral layer boundaries were all presented as necessary theoretical formulations on the physics of tubular pipe bending. This model was based on the analytical and numerical investigation. In principle, the application can be observed as the spooling of pipes, bending of pipes and reeling. Comparisons were made on two models developed on the finite element analysis in Simscale OpenFEA, namely the linear-elastic and the elasto-plastic models. This study presents visualization profiles using plastic strain to assess its effect on the tubular pipes. This can increase due to the limitation of plastic deformation on the composite materials selected.

The Mathematical Models of the Operation Process for Critical Production Facilities Using Advanced Technologies

The paper presents data on the problems of monitoring and diagnosing the technical conditions of critical production facilities, such as torpedo ladle cars, steel ladles. The accidents with critical production facilities, such as torpedo ladle cars, lead to losses and different types of damages in the metallurgical industry. The paper substantiates the need for a mathematical study of the operation process of the noted critical production facilities. A Markovian graph has been built that describes the states of torpedo ladle cars during their operation. A mathematical model is presented that allows determining the optimal frequency of diagnostics of torpedo ladle cars, which, in contrast to the existing approaches, take into account the procedures for preventive diagnostics of torpedo ladle cars, without taking them out of service. Dependence of the utilization coefficient on the period of diagnostics of PM350t torpedo ladle cars was developed. The results (of determining the optimal period of diagnostics for PM350t torpedo ladle cars) are demonstrated. The system for automated monitoring and diagnosing the technical conditions of torpedo ladle cars, without taking them out of service, has been developed and described.

Nanofluid Transport through a Complex Wavy Geometry with Magnetic and Permeability Effects

The current article incorporates the numerical investigation of heat exchange rate and skin friction carried out through nanofluid saturated with thermally balanced porous medium over a rough horizontal surface that follows the sinusoidal waves. The effects of the external magnetic field are discussed by managing the magnetic field strength applied normally to the flow pattern. The occurring partial differential governing equations are grasped through a strong numerical scheme of the Keller box method (KBM) against the various parameters. The findings are elaborated through tables and diagrams of velocity, temperature, skin friction, Nusselt number, streamlines, and heat lines. The percentage increase in Nusselt number and coefficient of skin friction over the flat and wavy surface is calculated which leads to the conclusion that the copper (Cu) nanoparticles are better selected as compared to the silver (Ag) for heat transfer enhancement. It is also evident from sketches that the current analysis can be used to enhance the surface drag force by means of nanoparticles. It is a matter of interest that the magnetic field can be used to manage the heat transfer rate in such a complicated surface flow. The current readings have been found accurate and valid when compared with the existing literature.

Developing and Investigating the Analyzers of Kinematic Viscosity and Density of Petroleum Products on Throttle Bridge Transducers

Measuring the viscosity and density of petroleum products is important for their proper production, transportation and application. Viscosity and density are the main parameters determining the composition and structure of petroleum products. Therefore, in the industry, to control the quality of petroleum products during various technological processes, automatic and non-automatic devices are used for their measurement. The accuracy of measuring the viscosity and density of petroleum products is an important factor. The authors analyzed different methods of measuring the viscosity and density of petroleum products and synthesized three versions of throttle bridge transducers. These versions implement differential measurement methods and have different numbers of laminar and turbulent throttles. The authors obtained new equations of static conversion functions by channels of measuring the kinematic viscosity and density of petroleum products of the proposed throttle bridge transducers. The authors developed a block diagram and designed measuring equipment to study experimentally the static characteristics of the throttle bridge transducers. The authors determined that the maximal relative deviations of the results of experimental studies from numerical calculations of a static conversion factor by channels of kinematic viscosity and density were 5.88% and 8.76%, respectively. The authors developed two versions of automatic devices for measuring the kinematic viscosity and density of petroleum products based on the proposed throttle bridge transducers. The first version is an automatic analyzer with tracking astatic balancing. The second version is an automatic analyzer with deployment balancing. The authors developed constructions of both versions of automatic analyzers and obtained the results of experimental measuring of the kinematic viscosity and density of petroleum products in different ranges.

The Choice of a Set of Operations for Forest Landscape Restoration Technology

The study is intended for forest farmers who need to make a mathematically sound and objective decision on the choice of technological operations and technical means for forest restoration. Currently, in studies implementing the forest landscapes restoration approach from the point of view of technology and the use of technical devices (FLR technology), there is some discreteness and fragmentation of the issues. There is a need for a comprehensive study of FLR technology using frontier techniques and devices, and the construction of a single technological FLR algorithm. Preliminary analysis indicates a sharp increase in the number of operational sets from nine for the implementation of the classical technological FLR algorithm to 268 in the first approximation when implementing the proposed algorithm. The FLR algorithm construction is based on the algorithm’s theory, and the verification of the similarity degree of operational sets is based on the cluster analysis by Ward and intra-group connections methods. The algorithm decomposition into six conditionally similar clusters will help plan new forest experiments taking into account interdisciplinary interaction, in addition to the modernization of plant propagation protocols for sustainable reforestation quality management. However, some questions remain for the future: which criterion should be used as a universal basis for choosing operational sets? How can the effectiveness of the FLR technology procedure be evaluated and predicted before its practical implementation?