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Khalismatov Irmuhammad, Ph.D. in Technical Sciences, Tashkent State Technical University, Uzbekistan Associate Professor of the Geology and Oil and Gas Exploration Department Buranov Mardon Davronovich, Senior Lecturer of the Life Safety Department Tashkent State Technical University, Uzbekistan Mukolyants Arsen Armanovich, Associate Professor of the Hydraulics and Hydropower Department Tashkent State Technical University, Uzbekistan E-mail: arsen5675@mail.ru
POSSIBLE USE OF SECONDARY ENERGY RESOURCES IN THE GAS COMPLEX OF THE REPUBLIC OF UZBEKISTAN
Abstract. The article analyzes the possibility for electricity generation without burning fuel by expanding high-pressure natural gas at gas distribution stations with lower specific energy costs.
Keywords: main gas pipeline, transported natural gas, gas distribution station, high pressure, gas expansion, power generation, technological pressure drop.
Energy saving solution development is one of the pressing issues of developed countries, and in Uzbekistan it is the most urgent.
The growth of economy and living standard increases the energy demand. In response to it, the generating capacities of the country were increased. A 300 MW power unit was commissioned at the Novo-Angren Thermal Power Plant (TPP), a 800 MW unit at the Talimarjan TPP, a project to expand the Navoi Thermal Power Plant with a 478 MW combined-cycle gas turbine plant (CCGT plant) was implemented, and a cogeneration gas turbine plant was installed at the Tashkent Thermal Power Plant with a capacity of 27 MW. Expander generator units were installed at the Syr Darya and Talimarjan TPPs for the projects on the use of unconventional and renewable energy sources. At the beginning of 2019. Epsilon Development Company began workover of well No.2 Khujum (Kultak-Kamashi investment block), and performed perforation at the depth of 3660-3718 meters. After well acidizing, average industrial daily flow of natural gas is about 145-180 thousand cubic meters.
The supply of gas to the head facilities of Shurtanneft-egaz LLC was started from Khujum well to the Nazarkuduk gas pipeline assembly point using the newly constructed 5.1 km gas pipeline. The company also received an industrial gas flow from two wells of the Talimarzhan field. The total hydrocarbon production by the company is expected to be 1-1.25 million cubic meters per day.
At the same time, Epsilon continues exploration work on the Kultak-Kamashi block and is developing the Shimoly Girsan, Devkhona, Chigil, Nazar-Khuduk and Ernazar fields.
Defining the prospects for improving the gas transmission system of the republic, the joint-stock company Uztransgaz (based on technical properties of transit transportation) can function in stages using various options for modernizing production and improving technological processes [1].
In this regard, to achieve the aforementioned objectives, a strategy has been developed to fulfill the main priorities in the field of transportation and supply of natural gas for 20112020, which envisages an increase in transportation capacity, diversification of transportation routes and rational use of natural gas resources.
Maintaining a high level of power capacity of the national economy can lead to the fact that unsatisfied demand will constitute a significant part of the current energy consumption in the republic. It will not be possible to cover this demand, given the depreciation of the key assets of the existing energy system, its high capital intensity and inertia.
Energy saving can be achieved by the use of expandergenerators units (EGU) for the generation of environmentally friendly electricity (without burning fuel) through the use of technological gas pressure drop in the systems of main pipeline transport and distribution of natural gas. With the existing gas supply system in the country, the pressure of the transported natural gas is usually reduced in two stages - at gas distribution stations (GDS) and at distribution pressure
Section 9. Technical sciences
regulating station (DPRS) and is carried out through pressure reduction.
Currently, projects to use the excess energy of gas pressure during its reduction in gas distribution and consumption systems in a number of EU countries are aimed at generating electrical energy. However, to date no practical measures have been taken for the large-scale and effective practical use of this technology in the republics of Central Asia, including Uzbekistan.
The level of useful output generated by the EGU will be determined by the turbine flow and the pressure drop. With the increase in these values, the generated electrical power increases.
To summarize, for uninterrupted power supply on the linear part of gas pipelines, gas metering devices for GDS and MS, and other gas supply facilities (nearby DPRS), the authors consider it appropriate to use (EGU) to generate environmentally friendly electricity by utilizing the energy of compressed natural gas.
The recent technical literature proposes many layouts for the use of EGU at GDS and DPRS. These layouts differ in the way the gas is heated - before and/or after the expander; sources of heat used for heating, and the resulting products. For example, EGU can produce only electricity, or in addition to electricity, liquefied natural gas, air separation products and generate cold (Fig. 2).
Figure 2. EGU installation layout: 1 - expander; 2 - generator; 3, 4 - high and low pressure pipelines; 5 - heat exchanger; 6 - gas pressure reduction site; 7 - heat exchanger; 8 - cold disposal
In this regard, it is necessary to conduct studies of thermodynamic laws during the operation of expanders, with different heating systems: before the expander; before and after the expander; in front of the expander and in the interval between the steps; in front of the expander, between the steps and after the expander. These studies would show how, at the same unit capacities, how the fuel consumption would change if the gas preheated before and after the expander compared to heating before the expander. The difference in costs will be determined by the amount of heat obtained directly from the low-potential source. It will be possible to choose the best way to heat the gas to improve efficiency.
One of the features of the turbo-expander developed by the authors is the placing of the turbine and compressor wheels on the same shaft, which determines the predominant use of impellers of radial or radial-axial types in order to simplify the design of the supply and dispose of the working medium. Therefore, to use the physical energy of the gas obtained by reducing the pressure on the GDS and DPRS,
instead of the traditional throttle devices, it is advisable to use EGU, which allow producing electricity using the gas pressure drop [2, P. 24-25].
The pressure of the transported natural gas is reduced at two steps. At the first - at gas distribution stations - the gas pressure decreases from the pressure in the gas pipeline from 5.5 MPa to 1.2 MPa, at the second - at DPRS - from 1.2 to 0.15 MPa. In the process of expansion of high-pressure natural gas in EGU, its pressure decreases to 1.2 MPa and temperature to 10 °C [3, P. 28-36].
Based on the above, the formulation of the optimization was created and presented in the following form: annual electricity generation
max E = f(P, G), (1)
where P e[p, Pj; G e[Gx, Gj.
Limits T2=0; T1 * Tmax; QhE * 0^ NEG * Nmax. (2)
Due to the fact that the expansion performed by expander leads to a more significant decrease in the gas
temperature, for economic comparison, the consumption The calculations were performed using the GazKondNeft
of fuel gas for a fired heater with a characteristic thermal thermodynamic calculations software [4], and the results are h = 40% was used. presented in (Table 1).
Table 1. - Comparison of parameters for natural gas expansion in the throttle and the expander
Type Parameter Gas outlet pressureMPa
0.3 0.6 1.2
Throttle The temperature of the transit gas after the throttle, °C -11.8 -9.6 -6.2
The amount of heat for the transit gas heating after the throttle (ta = 10 °C), kJ/h (kW) 693000 (190.5) 639700 (170.7) 532500 (140.0)
Fuel gas consumption for heating the transit gas after the throttle (h = 40%), mn3 50 46 40
Expander (heated after) Transit gas temperature after expander, °C -102.4 -81.2 -50.3
Expander power, kW 830 650 450
The amount of heat for the transit gas heating after expander (ta=10 °C), kJ/h (kW) 3700790 (1025) 3027500 (835) 2186600 (600)
Fuel gas consumption for heating the transit gas after the expander (h = 40%), mn3 270 220 160
Expander (heated before) The amount of heat for the transit gas heating after before (ta=10 °C), kJ/h (kW 5948900 (1650) 4341900 (1200) 2795800 (770)
Expander power, kWs 1400 1000 600
Fuel gas consumption for heating the transit gas after the expander (h = 40%), mn3 440 320 200
Transit gas temperature before the expander, °C 160.5 120.2 83.5
In summary, the calculations and operating experience of the expander-generator sets confirm the value of the relative power generation in the amount of40...60 kW/ths. mn3 and provide an opportunity not only to introduce into the
economic turnover of secondary energy resources and to ensure the production of electricity, but also to ensure the reduction of harmful emissions compared with traditional technologies.
References:
1. URL: http://old.uztransgaz.uz/ru/content/osnovnye-pokazateli
2. Гатауллина А. Р. Повышение энергоэффективности системы газоснабжения за счет утилизации вторичных энергетических ресурсов. Диссертация на соискание ученой степени кандидата технических наук / Уфимский государственный нефтяной технический университет, 2016.- С 24-25.
3. Гафуров А. М. Утилизация низкопотенциальной теплоты для дополнительной выработки электроэнергии при тур-бодетандировании природного газа в системе газораспределения // Вестник Казанского государственного энергетического университета. 2014.- № 1 (20).- С. 28-36.
4. Газ Конд Нефть // URL: http://gascondoil.com
