Classification of Separation Equipment by Design and Technological Features

Production range increasing causes many obstacles to ensure the work of the chemical industry. Production must respond quickly to the slightest change and must be customer-oriented. Due to this, there is a general trend towards increasing production flexibility by introducing modular systems. Thus, there is a need to classify existing solutions to develop flexible systems based on them. The article contains the analysis of chemical industry development tendencies, a methodology of research of modular separation devices, and their classification by design and technological features. The study result is a design and technological classification with a code that can optimize various separation devices. As a result of experimental research, preliminary and acceptance tests of experimental samples, the main hydrodynamic and separation characteristics of modular separation devices and combined multifunctional separators are determined: hydraulic resistance 0.15–2.00 kPa for units and 15–30 kPa for devices; effective capture of particles from the size of 5 μm; efficiency of separate stag es of modular separation devices is about 70–90 %; efficiency of combined multifunctional separators is approximately 99.5–99.9 %. The offered multipurpose separators equipped with dynamically regulated modular separation devices do not concede to world analogs by the main technical characteristics of combined multistage separators worldwide.


Introduction
The advantages of the modular approach in the design of separation equipment include reducing the weight and dimensional characteristics of the equipment and combining several technological processes in one module. All this, in turn, simplifies the process of development and implementation of automated control systems and improves the quality of product preparation [1].
However, this design method requires significant preparatory measures [2]. Unification of equipment [3], selecting interchangeable modules, setting up their interaction, and proper operation are the main problems in transitioning to a modular approach [4]. All these problems require the classification of separation equipment by design and technological features. Understanding classification, you can design modules of separation equipment, optimize their packaging, and coordinate.
Thus, the use of optimization packaging in the design of individual separation elements and equipment as a whole allows for simultaneously increasing basic operating parameters, efficiency, and intensity of separation. It also increases productivity to a new level, reducing separators' material consumption and capital and operating costs when their production and oil transportation refining energy costs [5].

Literature Review
Using a modular approach in design and production becomes relevant due to the mass introduction of Industry 4.0 in production and various spheres of human life. The future output vision includes modular and efficient production systems and characterizes the scenarios in which products control their production process [6,7].
The modular design approach to the modularity of devices aims to improve production, factories, and all the prerequisites [8].
The modular system is applied and widely studied in chemical production. Modular intensification of chemical processes is a growing trend in chemical engineering and can significantly improve chemical and production processes. Using a modular approach has advantages, including reduced energy consumption, cost savings, increased safety, and minimizing environmental impact. These benefits are key drivers and can accelerate the further development and application of modular intensification of chemical processes in the chemical, pharmaceutical industries, materials, pulp and paper, petroleum production, water treatment, and desalination [9].
There is also increasing differentiation and increasing product diversity [10]. There are two major development trends -a change in suppliers' market to buyers' market and a significant reduction in product life cycles [11,12]. It leads to a rapid response of production to new products, which requires flexibility in output.
The plants' modular technology based on the device's original concepts can be a solution to overcome this obstacle [13]. Production in modular and flexible installations requires new types of devices. Traditional operations with units are limited due to their inherent geometric factors, a small range of scalability, and lack of flexibility and modularity [14]. Innovative concepts of scaling, modularity and transition from interrupted to continuous operation are essential conditions in distributors and separators [15,16].
The use of modular systems implies that production can follow the market dynamics in time and space due to the rapid reconfiguration inherent in the modular units of such systems [17]. The time to market new products in response to immediate market requirements can be halved [18].
The advantages of the optimization techniques [19][20][21][22] can be used to design modular separation devices. Numerical modeling of hydrodynamics flow in phase separators was performed. The flow's hydrodynamic parameters were determined: the local velocity and density distribution and the free phase distribution surface height [23,24]. Comparing the simulation results with the corresponding regulations and operating parameters confirmed the numerical experiment's reliability.
Simulation of a dynamic separation device for use in horizontal phase separators was also performed. The experimental model of coagulation by imposing vibrations was proposed in [25]. It was determined that applying the methods mentioned above in the design of individual separation elements and equipment simultaneously increases basic operating parameters and economic indicators for oil transportation and refining to a new level.
The modular approach to design has already been considered on extraction centrifuges, an excellent example illustrating the increased flexibility implemented in the process. Fast and efficient design and scaling processes are quickly implemented in operations on a technical scale [26].
The modular principle is also used for flexible, modular settling tanks for the separation of multiphase systems. Thus, system analysis is systematized to ensure the possibility of transfer to other multiphase systems for equipment design purposes.
Morphology for the definition and description of each modular structure in the technology industry and the degree of its transformation determination and a model of potential analysis for this purpose was developed by Wörsdörfer et al. [27,28].
Despite some successful process intensification, the industry should overcome many obstacles to solve new issues for a continuous manufacturing approach [29][30][31][32]. The following existing research, analysis, and further research are carried out.

Implementation of a modular approach to the design of separation equipment
To ensure a modular approach in separation equipment design ( Fig. 1), both theoretical and experimental studies of the developed modular separation devices were conducted. As a result, their hydrodynamic parameters and separation efficiency in each of them were determined. Various combinations of them were also considered, as well as methods of installation in the separation equipment. They were divided into the inlet, main, and outlet.
From the determined hydrodynamic parameters of the flow, a conclusion was made about their optimal layout. In this case, the distribution of velocity and pressure at the outlet of the separation elements and secondary processes can occur both during the primary process and at the apparatus's outlet in non-design modes, affecting the separation process in subsequent modules, were taken into account. Separation equipment in which it is most expedient to install each of the developed elements was also selected. The results of the analysis of the obtained data. In this case, when designing the device, it is necessary to consider changing the package of existing modules to another, i.e., the possibility of practical disassembly and assembly of separators. For this purpose, it is necessary to exclude inseparable connections between the device and the frame of the package of modular separation elements. Notably, the technological process of assemblydisassembly efficiency of separation equipment is ensured by developing special machine tools used to manufacture modular separation devices.

Design and technological classification of modular separation devices
The existing classification of modular separation devices (MSD) only by design features does not reflect technological aspects essential in designing and manufacturing modular separation devices and devices for their manufacture. Therefore, the new classification should consider both the design of MSD and assess the technical aspects of their production. Based on a comprehensive analysis of MSD and its main technological features, a design and technological classification which considers all possible designs of MSD is proposed.
By type of processing, MSD can be divided into three categories: MSD, most parts of which are subject to machining by cutting; MSD manufactured using Locksmith operations; MSD manufactured using additive technologies and did not require machining (Fig. 2).
MSD elements can be metallic, non-metallic, and combined [33][34][35], affecting cutting tools and cutting modes in machining MSD parts. According to the crosssectional shape of the separation channels, MSD is divided into three categories: round parts, flat parts, and complex parts. This division allows choosing the type of technological equipment on which the processing of MSD parts will be performed By weight, MSD is classified into light (less than 10 kg), medium (10-100 kg), and heavy (more than 100 kg), which also determines the choice of technological equipment on which machining will be performed. In terms of overall dimensions, MSD is divided into small (less than 100 × 100 × 100 mm), medium (100 × 100 × 100-1000 × 1000 × 1000 mm), and large (more than 1000 × 1000 × 1000 mm), which determines the overall dimensions of machine tools, which produce parts of MSD.
Thus, the design and technological classification of MSD, which includes their production and technological features, has been developed. Based on this classification, it is possible to establish a structural code for selecting MSD for specific production needs and carry out the computer-aided design of technological processes to manufacture and assembly MSD parts into units based on MSD libraries. This approach can be used in information retrieval systems and reduce the design and technological preparation of production.

Results
As a result of modeling, primary and secondary processes of different nature accompanying the process of separation of multicomponent heterogeneous systems and intensifying the process of gas-family mixtures separation, several new separation and design methods of appropriate devices are proposed. A device for separating a dispersed liquid from a gas stream (Patent of Ukraine No. 102445) is provided. The device consists of a flowing element at the flow inlet into the casing and a stiffening ring at the casing flow outlet, which are interconnected by longitudinal blades attached to them in diameter at an angle. The blades on the flowing element are fixed rigidly, and on the stiffening ring -on the elastic elements, possibly bending the blades under the dynamic pressure. The device's application is separating dripping liquid from the gas stream in oil and gas, chemical, and other industries. An axial-tangential separation device is chosen as an analog to separate the liquid from a gas stream.
The device for the dispersed liquid separation from the gas flow in combination with all the essential features, including distinctive, allows to achieve a consistently high value of separation efficiency in conditions of sharp velocities and volumetric concentration of gas flow due to dynamic control of hydraulic resistance and flow velocity, as well as to prevent critical volumes of liquid from entering the separation equipment and accessing to the plug flow modes of operation.
The new method of highly dispersed droplet liquid captured from the gas-liquid stream, based on the latter's hydroaeroelastic interaction with deformable contact elements (Patent of Ukraine No. 130464), was also proposed (Fig. 3 a). This advanced method can be used in oil and gas, chemical, and other industries.

Classification of Separation Equipment by Design and Technological Features
Additionally, the highly dispersed droplet liquid captured from the gas-liquid stream in an advanced device for capturing the dispersed phase (Patent of Ukraine No. 111039) was proposed (Fig. 3 b). It includes the supply of gas-liquid flow into the separation package of plates, deviation of the trajectory of liquid droplets under inertia from the curved current line of gas-liquid flow enveloping the plates, deposition of droplets on the inner surface of the plates, their subsequent coagulation with liquid skinning, removing from separating zone skin of liquid flowing along the surface of the plates, characterized in that the supply of gas-liquid flow is carried out in a separation package of plane-parallel beveled at an acute angle elastic plates cantilevered at an acute angle to the trajectory of gas-liquid flow with the possibility of bending parabolic half-cylinder under the action of dynamic pressure (velocity pressure) of the flow and internal stresses arising in the plates. Also, the classification of modular separation devices, which allow receiving the structured code of the separation device depending on needs, was offered because of the research.
The design-and-technological classification of modular separation devices is presented in Fig. 4. The designs mentioned above and methods are of great practical importance, particularly for the separation equipment design. In particular, they can be installed as independent separation elements, which are planned to be located along the direction of gas movement as an auxiliary stage of purification of associated petroleum gas in devices such as "Heater-Treater", because these structures can solve the problem of reducing fluid mixtures to ensure the proper degree of purification of the gas supplied to the burners.
The proposed constructions and methods also have a practical application, in particular, in the optimization packaging of the gasoline separator of Hnidyntsi Gas Processing Plant [36], which has the form of a cylindrical vertical tank, where the baffle and overflow plates for gravitational-inertial separation of gas-liquid flow are located.
As far as light hydrocarbons in fine particles can be removed from the device with a gas stream, the discharge gas stream must be purified of the dispersed liquid. Therefore, the design of the gasoline separator provides for the net-shaped demister installation. However, the latter's main disadvantage is insufficient gas stream purification from the dispersed liquid. On the other hand, liquid droplets pass through a mesh packing with the gas flow at a relatively low gas flow rate.
On the other hand, the liquid accumulates in the bumper with increasing gas velocity, and there is a reintroduction of the droplet liquid. Both cases significantly reduce the separation efficiency of the dispersed phase.
To prevent the above problem, a dynamic separation element, the original modular separation device designed to capture fine particles with abrupt changes in the hydrodynamic parameters of the flow, is installed. In this case, to increase the amount of separated gas instead of installed at the inlet of the device drainboards, where the extraction of the main amount of gas from the gas-liquid mixture is carried out, it is proposed to place a vertical screw element, which provides higher degassing efficiency due to additional application of stripping gas flow and much larger free phase distribution surface. In the vertical screw element, a significant increase in the surface area of the phase distribution is achieved due to its more compact placement, and due to the direction in the opposite direction to the flow direction of the gas-liquid stream of a separate gas stream, the intensity of the degassing process increases.

Conclusions
To meet global trends of high market volatility, reducing product life cycles, increasing customer needs, and reducing development and production cycles, the transition to flexible modular production plants is a crucial approach to meet these needs. However, for the manufacture and implementation of modular devices, a precise classification of devices is needed. The article classifies modular separation devices according to their type, analyzes the design and technological features. As a result, the design and technological classification of modular separation devices was proposed. As a result of experimental research, preliminary and acceptance tests of pilot (experimental) samples, the main hydrodynamic and separation characteristics of modular separation devices and combined multifunctional separators are determined: hydraulic resistance 0.15-2.00 kPa for units and 15-30 kPa for devices; effective capture of particles from the size of 5 μm; efficiency of separate stages of separation (modular separation devices) -up to 70-90 %; efficiency of combined multifunctional separators -up to 99.5-99.9 %.