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13ПРИМЕНЕНИЕ НЕТРАДИЦИОННЫХ СЕПАРАЦИОННЫХ УСТАНOВОК ДЛЯ РАЗДЕЛЕНИЯ ГАЗОЖИДКОСТНЫХ ПОТОКОВ НА МОРСКИХ МЕСТОРОЖДЕНИЯХ
Гадашева Э.В.
Азербайджанский Государственный Университет Нефти и Промышленности, ассистент кафедры "Нефтегазовая инженерия "
APPLICATION OF NON-TRADITIONAL SEPARATION INSTALLATIONS FOR SEPARATION OF
GAS-LIQUID FLOW AT SEA FIELDS
Qadashova E. V.
Azerbaijan State Oil and Industry University. Oil and Gas engineering department, assistant
АННОТАЦИЯ
В данной работе был описан анализ газожидкостных потоков в сборе линий скважин и схемы по границам двухфазных потоков различных структурных форм. Показаны преимущество совместного транспорта газа и жидкости в сборе линий скважин. Были разъяснены причины низких значений эффективности существующих устройств разделения. Предложена схема низкотемпературной сепарации природного газа с использованием сепаратора трубы и разделительного теплообменника. Преимущества предлагаемой установки разделения природного газа были отмечены.
ABSTRACT
In this paper, an analysis of the gas-liquid flows in gathering lines of wells was given and the diagram on the limits of two-phase flows of different structural forms was described. The advantage of the joint transport of gas and liquid in gathering lines of wells were shown. The reasons for the low values of efficiency of existing separation devices were explained. A scheme of low-temperature separation unit of natural gas using a pipe separator and the separating heat exchanger was suggested. The advantages of the proposed installation of natural gas separation were noted.
Ключевые слова: давление, поток, скорость, структура, сепаратор, газоконденсат, скважина.
Keywords: pressure, flow, velocity, structure, separator, gascondensate, well.
Joint transportation of gas and liquid through the pipeline, in field practice, is inextricably linked with the development of a closed system for collecting two phase flows as they move from wells to separation units. According to this system, the length of throw-out lines and collector pipelines, through which joint collection and transportation of gas and liquid on land, is carried out approximately 2-3 km, and at sea fields more than 7-8 km. The idea of joint collection and transport (S.Vezirov's system) since 1948 in various ways received its further development in gas and oil regions.
This system, compared to the separate gas and liquid collection system significantly ensured a reduction in metal consumption and a reduction in capital costs in the fields. However, this system further creates certain difficulties in the work of trains of separation plants and the gas transmission system after separation plants. These difficulties for the above objects are as follows: —the trains of wells on land may have horizontal turning sections, and before separating installations these trains necessarily turn by 90° along the vertical plane. In sea conditions, in front of overpasses and platforms, the trains have sections of elbow and stand-up configurations. Just these areas that are stagnant zones, where the liquid phase accumulates and then is threw out by volley into the separation unit with undesirable pressure drops before and after these areas [1].
Gas-dynamic studies of two-phase flows through horizontal and vertical pipelines show that, depending on the flow rate (W), the diameter of the pipeline (D)
and the gas-containing consumption coefficient (P), two-phase flows can have numerous (about 50) structural forms. The criteria for these forms are determined by dimensionless numbers: the Froude number (Fr) and P coefficient. These values are determined by the following dependencies: Fr = W2/ gD and / = Qzj{Qza3 + ), here: W - is the flow rate,
D - is the diameter of the pipeline, g - is the acceleration of free fall, Qg and Ql - the costs of the gas and liquid phases, respectively. The value P=0 means that the flow consists of a liquid (without a gas phase), and P=1 -from a gas flow (without a liquid phase). In the vertically-standing section of the pipeline, the annular structural form of the gas-liquid flow is characteristic. In this case, the gas phase moves in an upward flow in the center of the riser, and the liquid phase moves along its walls. At high velocities of the gas flow, the liquid phase, taken by this flow, is carried away by it. However, during the accumulation of the liquid phase in the turning section of the pipeline and its periodical splashing into the vertical section of the pipeline, depending on the diameter of the riser and the physicochemical properties of the liquid, and with a decrease in the gas flow rate to a certain critical value, the reverse flow of liquid phase downwards can take place.
This oscillatory movement of the liquid phase will continue until the creation of a significant difference in the knee (turning section) of the pipeline. At higher
pressure drops in this section, the gas flow rate increases abruptly and the liquid phase will move upward with the gas flow again.
When pipelines are blown into the atmosphere, the formation of a foam-emulsion or gas-bubble structural form of the movement of two-phase flows in their final section is characteristic.
Of great practical interest in the gas transmission system are separate stratified structural forms of gasliquid flow, because with such forms there is a complete separation and continuous-stratified movement of two-phase flows. With such forms, in principle, the separation of gases in pipelines takes place. In this case, the completion of the separation process remains the removal of the separated liquid from the pipeline. These forms are made at the values of Fr < 10 and coefficient / > 0,95 . However, the removal and utilization of gascondensate from the pipeline in the field conditions (especially from sea trains) is practically not always possible. Thus, as a rule, the two-phase flow of the cork structural form of gas and liquid always enters the separation units.
Two-phase flows entering separation units in the volley-slug mode, typical for cork structural forms of gas and liquid, create great complications in the operation of these installations.
The existing method of calculating the separation process of natural gases based on the deposition of spherical droplets of the liquid phase due to gravity (Stokes model) does not take into account many gas-dynamic factors (fragmentation and dispersion of liquid plugs, entrainment of the dispersed liquid phase from the separation zone, inertial influence, etc.) and, most importantly, the structural forms of the gas-liquid flow at the separator inlet pipe are not taken into account. In the same method, the inverse proportionality of the ratios of flow rates at the separator inlet pipe (Wp) and at the separator itself (Wsep) with ratios of separator diameters (Dsep) and its inlet pipe (Dp), i.e. Wp/Wsep=Dsep2/Dp2, is passed. Moreover, for gravity separators, the optimal separation rate and the residence time of the flow in these separators are taken, respectively: Wsep = 0,1-0,15 m / s and t =50 s. However, in reality, the flow entering the separator by inertia keeps its previous velocity also in the separator and the residence time of the flow in the separator becomes much less than 50 seconds. Since the flow path here is no more than 2 meters, this stream leaves the gravity separator underseparated and with a significant amount of liquid entrainment [2].
Structurally, these separators consist mainly of large capacity for collecting the liquid phase. The upper peripheral zones of these separators do not participate in the process of gas separation and are stagnant areas, useless for phase separation. The separation zone itself in these separators is no more than 30% of their total volume. This design of separation units is quite beneficial for the implementation of oil degassing, which requires the existence of a large volume of evaporation of the liquid phase.
It should be noted, that the reason for the non-regular use of the same type of separation structures in oil
and gas fields is based on the historical fact that the industrial development of oil fields started earlier than the development of gas and gascondensate fields. Therefore, some technological processes and technical means (including separation units), used for the first time in the oil industry, were "inheritedly" transferred to the gas industry. However, a very significant difference in the mechanism of oil degassing with a small amount of gas dissolved in it and the process of separation of natural gas with a small amount of liquid dissolved in it requires different methods of technological calculations of these processes and, accordingly, different designs of technical means for carrying out these processes. As a result of the above reasons, modern gas separators operate with an efficiency of about 50-60%.
Analysis of the operation of centrifugal cyclone separators showed that these separators also work with a low efficiency in the separation of the initial flows with the cork structural forms of gas and liquid. In this case, these separators work even worse than gravitational ones. In the process of gas separation in centrifugal separators, a large mass of the liquid phase in the initial flow in the form of plugs or films under the influence of centrifugal forces is fragmented and a significant part of this sprayed liquid is carried away by an underseparated gas flow.
In recent years, reconstructed separation plants have been proposed with placing inside them of various separation elements, such as grids, cartridges, rods, plates, reflectors, cyclones, rings, etc. However, revisions of the insides of such separation units show that these elements work in an aggressive field environment quickly fail and create additional local resistance.
As a result of the low efficiency of the existing separation plants two-phase flows of the gas-liquid mixture appear again after them in the gas transmission system. In this system the liquid phase can appear even with full observance of the thermodynamic conditions of the process of low-temperature gas separation due to the unsuitability of existing separation devices for the separation of natural gases.
As mentioned, the joint transportation of gas and liquid in the trains of wells has a certain advantage in terms of technical and economic efficiency. However, the presence of a liquid phase in the system of main gas pipelines after separation units only leads to negative consequences. The presence of the liquid phase in the separated gas shows its low quality of preparedness for transportation and it creates the following significant difficulties in operation in the gas consumption system:
-increased hydraulic resistance of gas pipelines and decreases their throughput;
- internal corrosion and erosion of pipelines grows and their service life is reduced;
- a condition for the formation of gas hydrates, requiring additional costs to prevent or eliminate the process of hydrate formation is created;
- valuable fractions of hydrocarbons to be processed to produce gas gasoline and liquid gases are lost;
-the working conditions of checking and measuring instrumentation and automation deteriorate.
Taking into account these difficulties in the gas transportation system, the reasons for which are the imperfection of the technology and technique of low-temperature gas separation units, the author proposes an alternative gas preparation scheme using separators and pipe-type heat exchangers.
The proposed scheme for the installation of low-temperature gas separation unit (LTSU) consists of: an inlet pipe, separation heat exchanger with a diaphragm, choke device, pipe separator, tank for collecting liquid, line for draining the liquid and separated gas. The diameters of the separation heat exchanger and the pipe separator are taken with view of the creation inside them a separate-layered structural form with a smooth liquid-gas interface, i.e.
W2
Fr < — = 10 . gD
The flow rate is determined from the dependence of the gas consumption:
Q = 67824PWD2, W = Q/67824PD2. Based on the indicated dependencies, after several mathematical transformations, the allowable diameter of the pipe for the formation of a separately stratified structural form of gas and liquid in pipe separators can be determined by the dependence: d = 0,004668(Q/P)0,4 where D - the diameter of the tube separator; Q -gas consumption through the pipeline, m / day; P - operating pressure, atm .
According to the proposed scheme, the initial gasliquid flow in various structural forms through the inlet line enters the separation heat exchanger, which simultaneously performs the functions of a heat exchanger and a first-stage separator. Here, the gas-liquid flow during the movement of a separately stratified structural form is released from the free part of the liquid
phase and is pre-cooled with a returnable cold separated gas. In this case, partial condensation of the source gas stream also takes place.
Then the pre-treated gas stream in a single-phase gas state passes through the throttle device and is cooled to a predetermined low temperature. Further, this cooled flow in a two-phase state enters the pipe separator, where the gas is finally separated. The separated liquid phases from the two pipe separators are merged into liquid pipe containers and from there are transferred to the liquid removal lines. The completely separated cold flow from the second pipe separator is directed through the separation heat exchanger to the consumer's gas pipeline.
The advantages of the proposed LTSU scheme are as follows:
LTSU is released from large-sized standard separators of high metal capacity and operating with low efficiency;
- in a "pipe in pipe" type heat exchanger, two processes are carried out simultaneously: pre-cooling and gas separation, thereby significantly reducing metal consumption;
- in both pipe separators, the gas separation rate is several ten times greater than the separation rate in the existing standard separators, that shows the high throughput of the proposed LTSU;
-the use of a "pipe in pipe" type heat exchanger instead of the standard multi-tube heat exchanger prevents blockage of the living section of small-diameter tubes by mechanical sedimentation and reduces the possibility of gas hydrates formation in these pipes;
- all equipment according to the proposed LTSU can be made of standard pipe elements by the manufacturers themselves without a factory customer-manufacturer.
Fig. 2. Principle technological scheme of the installation of low-temperature gas separation using a separation heat exchanger and a pipe separator: 1 - input line; 2 - separation heat exchanger; 3 - diaphragm; 4 - pipe separator; 5 - choke device; 6 - tanks for collecting the liquid phase; 7 - line for drainage of the liquid phase; 8 -
line of separated gas.
Conclusions:
1. The movement of two-phase flows in the system of collection, separation and transport of gas was analyzed;
2. The results of gas-dynamic studies of gas-liquid mixture flows in various sections of pipelines are described on the basis of the structural form diagram in the joint movement of gas and liquid;
3. A technological scheme of a low-temperature gas separation unit is proposed using a separation heat exchanger and a pipe separator;
4. The advantages of the proposed scheme for the installation of low-temperature gas separation in the field preparation of gas for transport are shown.
References
1. Aliev E.U., Abdullaev E.A., Sultanov N.N. // Gas separation in pipelines. Ed. "Nafta-Press": Baku -2006, - 205 p.
2. .Mustafayev A.R., Abdullayev A.A., Panahov R.A., Sultanov N.N., Gadashova E.V. // Preparation of gases for transport, "Nafta-Press" : Baku,- 2015,- p.85-120.
COMPUTER TECHNOLOGY AND UNMANNED VEHICLES
Ivanko A.,
Professor, Moscow Polytechnic University
Ivanko M.,
Associate Professor of Moscow Polytechnic University, Ph.D.
Kolesnikova O., student of the Moscow Polytechnic University
Kulikova E.,
Associate Professor of Moscow Polytechnic University
Vinokur A.
Moscow Polytechnic University Professor
ABSTRACT
Innovative technologies, computer equipment make it possible today to put into practice artificial intelligence systems. There are control systems for airplanes and locomotives on railways, and at last real automatic control systems of modern cars began to appear. The era of high technology and automation of many activities, computers began to do a huge part of our work, both in everyday life and in the professional sphere. All this certainly simplifies our lives, so the developers do not stop and more often they surprise us with new projects.
To date, one of the most talked about new technologies is the development of unmanned vehicles. Many companies have started production of such cars, testing them on public roads. The article discusses the origins of the emergence of unmanned vehicles, analyzes the current state of the problem, assesses development prospects using information technologies.
Keywords: unmanned vehicles, IT-technologies, innovative projects, computer technologies, control automation.
An unmanned vehicle is a vehicle equipped with an automatic control system that can travel without human intervention.
The development of unmanned vehicles is accompanied by a number of ethical problems, including: moral, financial and criminal liability for accidents, decisions made by a car before a potentially fatal collision, problems of data protection and problems of losing jobs.
Consider the history of the creation of unmanned vehicles.
Many people may have a false opinion that the history of the development of unmanned vehicles originates in the XXI century. However, few people know that the first attempts to create a fully autonomous car were made in 1980. For example, if you go to the archive of The New York Times articles, then at the request of "unmanned vehicles", a large amount of materials 15 years ago will appear.
There are different data when the first fully autonomous vehicles appeared. The fact remains that initially
all such developments were created for military purposes. At the beginning of the 20th century, the first research began in the field of unmanned aerial vehicles. As early as 1916, Archibald Lowe created the first drone, a radio-controlled aircraft. During the First World War, air torpedoes and self-propelled German mines were already actively used.
However, until the middle of the 20th century, developments in the field of unmanned technology were experimental rather than practical, and, in one way or another, no single model could manage without direct human participation. Unmanned vehicles, like flying drones, were initially conventional remote control prototypes, and only gradually became autonomous.
The first experiments to create an unmanned vehicle date back to the early 1960s. In 1961, a student at Stanford University, James Adams, as part of his scientific work, created a prototype of a self-guided cart, better known as the "Stanford cart" (Fig. 1).
