The article discusses the possibilities of generating electricity without burning fuel by expanding high-pressure natural gas at gas distribution stations with lower specific capital costs. It is proposed to reduce the pressure of the transported natural gas using expander-generator units instead of traditional throttle devices.

Document type: Articl

Buranov, M.

Mukolyants, A.

Sotnikova, I.

Scipedia

*Corresponding author: arsen5675@mail.ru **Corresponding author: word2605@yahoo.com Generation of electrical energy at gas pipelines using a transported natural gas technological pressure drop M.D. Buranov 1, A.A. Mukolyants 1,*, I.V. Sotnikova 1,** 1Tashkent State Technical University, Tashkent, Uzbekistan Abstract.The article discusses the possibilities of generating electricity without burning fuel by expanding high-pressure natural gas at gas distribution stations with lower specific capital costs. It is proposed to reduce the pressure of the transported natural gas using expander-generator units instead of traditional throttle devices.   Currently, renewable forms of energy are one of the promising areas of scientific and technological progress. Renewable types of energy include solar, wind, heat, tidal energy, as well as the development of principles for the return of part of the energy spent on transporting natural and associated petroleum gases through main pipelines from source to consumer. The problem of energy conservation, being one of the most important problems in all developed countries, is becoming especially acute in Uzbekistan. With the growth of the economy and the standard of living of the population, the demand for energy has also increased. In this regard, in recent times, the generating capacities of the country's power system have noticeably increased. A 300 MW power unit was commissioned at New Angren Thermal Power Plant (TPP), as well as an 800 MW unit at Talimarjan TPP; a project was completed to expand Navoi TPP with the construction of a combined cycle gas turbine unit (CCGT) with a capacity of 478 MW, and a cogeneration gas turbine unit was introduced at the Tashkent Thermal Power Plant. with a capacity of 27 MW. In the framework of projects on the use of alternative and renewable energy sources, expansion units were introduced at Syrdarya and Talimarjan TPPs. At the beginning of 2019, Epsilon Development Company commenced re-commissioning of Khujum well No. 2 (Kultak-Kamash investment block) and the overhaul was initiated, the work on perforation in the range of 3660-3718 meters was performed. After acid treatment of the well, an industrial influx of natural gas in the amount of about 145-180 thousand cubic meters per day was obtained. From the discovered Khujum field, along the newly built 5.1 km gas pipeline connecting the Khujum field with the gas collection point of Nazarkuduk gas pipeline, gas production was started at the headquarters of Shurtanneftegaz LLC. The company also received an industrial flow of gas from two wells in Talimarjan field. Thus, it is expected that the total volume of hydrocarbons produced by the company will be 1-1.25 million cubic meters per day. Determining the prospects for improving the gas transmission system of the republic, Uztransgaz joint stock company, in terms of the technical properties of transit transportation, can operate in stages using various options for modernizing production and improving technological processes [1]. Maintaining a high level of energy intensity of the national economy can lead to the fact that unmet demand will make up a significant part of the current energy consumption in the republic. It will be impossible to cover this demand, given the deterioration of the fixed assets of the existing energy system, its high capital intensity and inertia, without intensifying work in the field of energy conservation. One of the areas of energy conservation is the use of expander-generator units (EGU) for the production of environmentally friendly electricity (without burning fuel) through the use of a technological pressure drop of gas in the systems of transportation via main pipelines and distribution of natural gas. With the gas supply system existing in the republic, the pressure of the transported natural gas is usually reduced in two stages - at gas distribution stations (GDS) and gas control points (GCP) and is performed by throttling. Currently, projects to use excess energy of gas pressure during its reduction in gas distribution and consumption systems in a number of EU countries are aimed at the production of electric energy. However, to date, no practical measures have been taken for the large-scale and effective practical use of this technology in the Central Asian republics, including Uzbekistan. In this regard, for uninterrupted power supply on the linear part of gas pipelines, gas metering devices at gas                        , 0Web of Conferences https://doi.org/10.1051/e3sconf/20191390 E3S 139 (2019)10 1089RSES 201989   © The Authors,  published  by EDP Sciences.  This  is  an open  access  article distributed under the  terms of the Creative Commons Attribution License 4.0 (http://creativecommons.org/licenses/by/4.0/).  distribution stations and gas storage facilities, and other gas supply facilities, the authors consider it appropriate to use EGU to generate clean electricity by utilizing compressed natural gas energy. Studies conducted at Urga, Northern Shurtan and Northern Berdak fields (tab. 1,2,3) showed that the use of transported reservoir gas in turboexpander units requires additional processing and bringing it to the relevant technical standards. Table 1 Initial composition of the reservoir gas of Urga field (% mol.)  Analysis of the obtained data suggests the need to install an additional filter before entering the expander unit for removing mechanical impurities from the gas during transportation and for reducing the percentage of condensate. A characteristic feature of the turbo-expander design developed by the authors is location of the turbine and compressor wheels on one shaft, which determines the predominant use of radial or radial-axial runners in order to simplify the design of the supply and removal of the working medium. In this regard, to use the physical energy of the gas, obtained by reducing the pressure on GDS and GCP, instead of traditional throttle devices, it is advisable to use EGU, which allow to generate electricity due to the pressure drop of the gas [2-5].  Table 2. Initial composition of the reservoir gas of ShimoliyBerdak gas condensate field Composition of the gas (molar %) Res. J311 Res. J39 Res. J38 Res. J27 well 9 well 3 well 7 well 14 Average well 6 well 7 well 10 Average Perforation range 1577-1566, (m) Perforation range 1988-1980, (m) Perforation range 2024-2017,   (m) Perforation range 1991-1988,  (m) Perforation range 2226-2217,  (m) Perforation range 2222-2218,  (m) Perforation range 2139-2136,  (m) СН4 87,12 92,21 92,31 89,95 91,49 92,95 92,90 94,08 93,49 С2Н6 6,36 3,81 3,05 4,0 3,62 3,78 3,10 2,41 2,76 С3Н8 3,05 1,53 1,50 1,72 1,58 1,31 1,48 1,23 1,36 iso-С4Н10 0,78 0,24 0,20 0,50 0,31 0,22 0,16 0,32 0,24 n-С4Н10 0,82 0,23 0,17 0,42 0,27 0,22 0,15 0,30 0,23 С5Н12+higher 1,33 0,49 0,47 1,19 0,72 0,42 0,42 0,63 0,53 N2 0,43 1,33 1,53 1,49 1,45 0,75 1,07 0,93 1,0 H2S - - - - - - - - - CO2 0,11 0,16 0,77 0,73 0,55 0,35 0,72 0,10 0,41 Total 100 100 100 100 100 100 100 100 100 Potential condensate content, g/m3  - in 1 m3 of reservoir gas 57,48 23,7 22,4 51,83 32,31 20 20,3 29,32 24,81  - in 1 m3 of dry gas 58,25 23,8 22,5 51,44 32,58 20,1 20,4 29,51 24,96 Potential ethane content, g/m3 79,55 47,65 38,15 50,03 45,28 47,28 38,77 30,14 34,52 Critical parameters:  - Рcr., kgf/cm2  46,57   46,73   46,88 46,73 46,79 46,89 46,94 46,71 46,82  - Tcr., K 211,53 199,9 199,26 199,95 199,7 199,7 199,20 198,75 198,97 Gas density at 200С,   760 mm Hg, kg/m3 0,824 0,746 0,746 0,746 0,746 0,739 0,741 0,739 0,740 Relative gas density 0,684 0,62 0,620 0,619 0,619 0,613 0,615 0,613 0,614 Gas components Horizons J32 J33 J35+6 J37 Well 7 Well 8 Well 4 Well 11 Well 6 Well 8 CH4 86,75 87,40 88,30 92,54 89,18 88,41 C2H6 7,05 6,60 5,57 4,09 5,98 6,52 C3H8 1,85 1,85 1,98 1,01 1,54 1,81 iC4H10 0,24 0,25 0,34 0,16 0.26 0,31 nC4H10 0,38 0,35 0,48 0,19 0.26 0.38 C5H12+higher 0,47 0,45 0,57 0,42 0,37 0,63 N2+rare 3,12 2,30 2,49 0,70 0,74 1.28 CO2 0,14 0,80 0,27 0,89 0,67 0,66 H2S - - - - - - Content of C5+higher: - % mol. - g/m3  0.47      22,3  0,45      22,3  0,57   22,3  0,42     22,3   0,37      22,3  0,63      22,3 Molecular mass of C5+higher 114,062 119,132 94,051 94,051 94,051 85,094 Gas density (760 mm Hg 200C), kg/m3 0,777 0,778 0,771 0,742 0,772 0,771 Relative gas density (760 mm Hg 200C) 0,645 0,646 0,640 0,613 0,641 0,640                        , 0Web of Conferences https://doi.org/10.1051/e3sconf/20191390 E3S 139 (2019)10 1089RSES 2019892 Continuation of Table 2 Composition of the gas (molar %) Res. J23а Res. J22а Res. J22б well 14 well 16 Average well 9 well 15 Average well 16 Perforation range 2468-2463 (m) Perforation range 2452-2444 (m) Perforation range 2552-2545 (m) Perforation range 2516 -2504 (m) Perforation range 2615-2605 (m) СН4 92,76 89,14 90,95 92,39 90,99 91,69 92,60 С2Н6 2,56 4,50 3,53 2,46 4,57 3,52 3,44 С3Н8 1,89 2,21 2,05 1,92 0,65 1,29 0,72 iso-С4Н10 0,45 0,51 0,48 0,32 0,37 0,35 0,20 n-С4Н10 0,44 0,54 0,49 0,27 0,41 0,34 0,25 С5Н12+higher 0,90 1,08 0,99 1,20 0,80 1,0 0,66 N2 0,48 1,24 0,86 0,71 1,58 1,15 1,34 H2S - - - - - - - CO2 0,52 0,78 0,65 0,72 0,63 0,63 0,79 Total 100 100 100 100 100 100 100 Potential condensate content, g/m3  - in 1 m3 of reservoir gas 39,24 48,73 35,68 57,81 32,32 45,07 32,11  - in 1 m3 of dry gas 39,60 49,23 35,96 58,51 32,58 45,55 32,32 Potential ethane content, g/m3 32,02 56,28 44,15 30,77 57,16 44,03 43,03 Critical parameters:  - Рcr., kgf/cm2 46,80 46,84 46,81 46,74 46,81 46,77 46,90  - Tcr., K 202,32 205,09 203,8 203,08 201,14 202,40 199,34 Gas density at 200С,   760 mm Hg, kg/m3 0,763 0,782 0,773 0,777 0,760 0,764 0,748 Relative gas density 0,634 0,649 0,642 0,645 0,631 0,634 0,621  Table 3. Physical and chemical characteristics of the gases of North Shurtan field          Free gas    Oil dissolved gas Density (by air) 0,652 0,706 Content, in volume %:  methane 87,8 81,62 ethane 4,98 6,34 propane 2,48 3,84 isobutane 0,56 1,25 normal butane  0,64 1,79 isopentane 0,18 0,7 normalpentane 0,09 0,45 hydrogensulfide 0,15 0,05 carbondioxide 1,68 1,58 nitrogen 1,44 2,68 Calorificvalue, kcal/nm3 8712 9670  The pressure reduction of the transported natural gas is carried out in two stages. At the first stage - at gas distribution stations - gas pressure decreases from the pressure in the main gas pipeline from 5.5 MPa to 1.2 MPa, at the second stage - at gas control points - 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. [6-9]. Based on the above, a statement of the problem of optimization was formed and presented in the following form: annual electricity generation maxE = f (P,G),               (1) where Pϵ [P1,P2] ;  Gϵ[G1,G2]. Limitations   Т2=0;   Т1≤ Тмаx;  QTO ≤ Qмаx;    NЭГ≤ Nмаx.(2) Due to the fact that expansion with the help of an expander leads to a more significant decrease in the gas temperature, for economic comparison the fuel gas consumption for a fire heater with a characteristic thermal h = 40% was taken into account in the calculations.                        , 0Web of Conferences https://doi.org/10.1051/e3sconf/20191390 E3S 139 (2019)10 1089RSES 2019893 The calculations were performed using the GasCondOil thermodynamic calculation program [10], and the results are presented in Table 4.  Table 4. Comparison of natural gas expansion parameters on throttle and expander Type Parameter Outlet gas pressure, MPa              0,3            0,6            1,2  Throttle Transition gas temperature after throttle, °С             -11,8          -9,6          -6,2 Heat quantity to heat transit gas after throttle (tk = 10 °С), kJ/hour (kW)               693000              (190,5)             639700              (170,7)              532500              (140,0) Consumption of fuel gas for heating transit gas after throttle  (h = 40%), nm3         50             46            40 Expander (heating after) Transit gas temperature after expander, °С        -102,4               -81,2            -50,3 Expander capacity, kW         830              650             450 Heat quantity to heat transit gas after expander (tk=10°С), kJ/hour (kW)  3            700790              (1025)              3027500              (835)            2186600           (600) Consumption of fuel gas for heating transit gas after expander (h = 40 %), nm3            270             220            160 Expander (heating before) Heat quantity to heat transit gas before expander (tk=10°С), kJ/hour (kW)              5948900               (1650)             4341900              (1200)            2795800           (770) Expander capacity, kW              1400               1000            600 Consumption of fuel gas for heating transit gas before expander (h = 40 %), nm3          440              320           200 Transit gas temperature before expander,°С            160,5              120,2          83,5  Thus, the calculations and operating experience of expander-generator sets confirm the value of relative power generation in the amount of 40 ... 60 kW/thousand nm3 and make it possible not only to introduce secondary energy resources into the economy and provide the generation of electricity, but also to reduce the level of harmful emissions in comparison with traditional technologies. References 1.URL: http: //old.uztransgaz.uz/ru/content/osnovnye-pokazateli 2. V.Gurov, EES, 4, 22-24 (2006). 3. O.Malkhanov, RSE, 1, 39-41 (2008). 4. E.Marchenko,  O.Malkhanov, RSE, 6, 38-42 (2009). 5. H.Fasold, GEG, 6, 261-269 (1995).  6. A.Gafurov, BKSEU, 1, 28-36 (2014) 7. I.Kharisov, STSSPbSPU, 1, 119-123 (2012). 8. B.Agababov, ESWT, 1, 71-73 (2011).   9. O.Sorokin, IPE, 6, 36-41 (2005).  10. // URL: http://gascondoil.com/GazCondOil                        , 0Web of Conferences https://doi.org/10.1051/e3sconf/20191390 E3S 139 (2019)10 1089RSES 2019894

Generation of electrical energy at gas pipelines using a transported natural gas technological pressure drop

https://www.scipedia.com/wd/images/b/ba/Draft_Content_348658338-beopen51-5873-document.pdf

Generation of electrical energy at gas pipelines using a transported natural gas technological pressure drop

Abstract

Similar works

Full text

Available Versions

Scipedia