Please use this identifier to cite or link to this item: http://hdl.handle.net/11527/17033
Title: Doğal Gaz Boru Tesisatlarının Tasarımında Kullanılan Yöntemlerin Geliştirilmesi
Other Titles: Modifications Of The Methods Used In The Design Of Natural Gas Installations In Residential Buildings
Authors: Zeybek, Murat
Durak, Levent
46479
Petrol ve Doğal Gaz Mühendisliği
Petroleum and Natural Gas Engineering
Keywords: Boru tesisatları
Doğal gaz
Piping
Natural gas
Issue Date: 1995
Publisher: Fen Bilimleri Enstitüsü
Institute of Science and Technology
Abstract: Bilindiği gibi konutlarda doğal gaz şebekesinin tasarımında basınç kaybını hesap etmek için 7363 sayılı Türk Standardındaki Grafik 1 ve 2 kullanılmaktadır. Bu grafiklerin hazırlanmasında kullanılan doğal gaz yoğunluğu Türkiyede kullanılan doğal gaz yoğunluğundan daha fazladır, ayrıca hesaplamalarda oldukça yüksek bir pürüzlülük değeri alınmaktadır. Bu çalışmada doğal gaz yoğunluğunun ve boruların mutlak pürüzlülüğünün duyarlılığı araştırılmakta ve TS 7363, menü ile kolay kullanılabilir bir yazılım programına dönüştürülmektedir. Gerçek yoğunluk ve mutlak pürüzlülük değerleri kullanıldığında basınç kaybında önemli azalmaların olduğu gözlenmiştir. Bu değişiklikler sonucunda boru çaplarında azaltmaların yapılabileceği gösterilmiştir. Sonuç olarak konutlarda doğal gaz şebekesinin maliyeti bir ölçüde azaltılabilir. Bunlara ilaveten laminer ve türbülans rejimler arasındaki kritik bölge de hesaplamalar için grafiklerde tanımlı hale getirilmekte ve gereğinden büyük boru çapı seçimini önlemektedir. TS 6565, kapsamı gereği yanıcı gazların taşınması ve dağıtımı sırasında hatlardaki basınç kayıplarınının hesaplanmasında kullanılmalıdır. Ancak piyasada konutsal gaz şebekeleri için TS 7363 ve endüstriyel gaz şebekeleri için de Renouard denklemleri yaygın bir şekilde kullanılmaktadır. Piyasada TS 7363 ve TS 6565 'in farklı hesaplama yöntemleri içerdiği ve bu yüzden hangisinin kullanılması gerektiği yolunda bir soru işareti bulunmakta ve Türk Standartları Enstitüsünün aynı konuda birden fazla standart yayınladığı için kargaşaya sebebiyet verdiği iddia edilmektedir. Çalışmanın ikinci kısmında TS 6565 tam bir çözüme kavuşturulmaya çalışılmış ve alçak basınçlı hatlar hesap tekniğinin birkaç varsayım dışında TS 7363 ile tam bir uyum içinde olduğu gösterilmiştir. Yüksek basınçlı hatlar hesap tekniği de tekrar çözülerek eksiklikleri tartışılmıştır. Üçüncü kısımda boru hatları tasarımında çok kullanılan ve neredeyse temel denklem varsayılan analitik denklemler; Weymouth denklemi ve onun daha çağdaş bir uyarlaması olan Panhandle 'in iki denklemi TS 6565 ve TS 7363 'de kullanılan Darcy- Weisbach teorik denklemi ile karşılaştırılmışlardır. Ayrıca İGDAŞ tarafından bütün endüstriyel gaz tesislerin basınç kaybı hesaplarında kullanılan Renouard denklemleri de aynı karşılaştırılmaya tabi tutulmuşlardır. Bunlara ilaveten yukarıda adı geçen ve literatürde bu konuda verilmiş bazı denklemlerin türetilmesinde esas alman sürtünme etkeni denklemleri Moody çizgesinde (diyagramında) çizilerek gösterilmiştir.
This thesis consist of three parts which basically focused on the methods used in the design of the natural gas installation in industrial and residential buildings. In the first part of this thesis, pressure loses and the pipe size selection are investigated in residential buildings. When calculations of TS 7363 is investigated, it is understood that the density of natural gas is taken to be 0.7936 kg/m3. As stated TS 7363 the density of natural gas varies between 0.65 ~ 0.70 kg/m3 in Turkey. For residential buildings, pressure loss equation in terms of mbar is given by AP = 6.25X v2pL (lOOd;)5 X is known to be friction factor and is given by the following equation if the flow is laminar; X = 64 Re and if the flow is turbulent: -j= = -2log 2.51 k -+- Re-Jx 3.71*103di Pressure losses for pipe fittings are given; apf=^tv 200^ xin A typical application showed that on the average 15% of less pressure loss is calculated using 0.675 kg/m3 density value instead of 0.7936 kg/m3. Second, the effect of absolute roughness is studied. As stated in TS 7363, the absolute roughness is taken to be 0.5 mm for commercial steel pipes. As known, absolute roughness value for steel pipes is not more than 0.05 mm [10]. Typical calculation showed that approximately 30% of less pressure loss is obtained for 0.05 mm absolute roughness instead of 0.5 mm. Third, the critical region in Moody 's chart is studied. When the Moody 's chart is investigated carefully, it can easily be seen that a region between turbulent and laminar regimes is undefined. However, turbulent regime equations are extended to critical region for the pressure loss calculations. In the thesis, appropriate equation that defines critical regions is used and the Moody 's chart is completed for this region. It appears to be the modification of this region quite significant when the rates are in that region. By considering all the modifications that described above, an application similar to real one is selected including oven and furnace of a unit of an apartment compared with TS 7363 calculations. Modified solution yielded reduction in pipe sizes for three sections maintaining less pressure loss compared to TS 7363 calculations. As a result of first part, the cost of natural gas installation in residential buildings may considerably be reduced and calculations can be carried out easily turning into menu driven user friendly software. In the second part of this thesis, pressure losses and the pipe size selection are investigated in industrial installations. Although, TS 6565 should be used in the calculation of pressure losses in residential installations, Renouard equations are often used for its simplicity. A constant friction factor is used for all region in TS 6565. TS 6565 is used in two different pressure stages, the first stage of TS 6565 is for the low pressure installation and the second stage is for high pressure installation. In order to yield simple solution, the first stage is reduced to first order equation which is derived from energy balance equation that is, AP = RND Lv2 where Rmd is resistance coefficient which includes friction and fitting losses. Actually Rnd can be given as follows; ^=6.25*10-,0Â^- XIV This equation is equal to Darcy-Weisbach equation in TS 7363. Rnd values are given in Chapter 3. These Rnd values are calculated by using nominal diameters. Consequently Rnd values need to be corrected to real diameters. This provides simplicity to user. However there is an error occurring due to the difference in nominal and real diameters. This error is also for determination of friction factors. Second, when Reynolds numbers are calculated, velocity is taken to be 3 m/s. In fact, the flow velocity changes in a wide range between 0.2 ~ 15.7 m/s. Whole range of this velocity is given in Table 3.1. Third, von Karman 's fully rough turbulent regime equation is used to obtain friction factor. As known, von Karman equation does not work properly in transition region which yields between fully rough regime and smooth regime. Flow regime is mostly in transition region where Colebrook equation has to be used. In contrast, TS 6565 assumed that friction values are constant for all regimes. Fourth, pipe roughness is taken between 0.1 -3.0 mm depending on the age of the transmission line and the number of fittings in the line and precipitation is in the pipe. It means that ifa pipe line has many fittings the roughness is around 3.0 mm and 0.1 mm if it has no any fittings. This is qualitative scale that should not to be included in a national standard. It is advised to use a value of 0.5 mm as an average. If we have a pipe line without any fittings we should use 0. 1 mm which is greater than commercial steel pipe roughness value of 0.05 mm. Therefore it gives higher friction factor value and higher resistance coefficient Rnd and it produces higher pressure loss. In higher pressure stage pressure loss equation is given in the quadratic form of energy balance equation instead of first order equation. That equation is given by; P> - P> = RHD Lv> Rhd values are also given in chapter 3. The equation of high pressure stage also has same problem of first order equation. Here assumption of flow velocity that still deviates from real values is 10 m/s. First order equation needs some correction for diameter, density, pipe line working temperature, altitude and pipe line working pressure if necessary. This correction equation can be given by; P, -P, = RNnLv2f ^NOMINAL ' R Lv2| ^NOMINAL 1 f PACTUAL Y TACTUAL Y 1013 Y 1013 + 30 I ^actual J I °M A 283 Aioi3-o.loi3*HXloi3+Ply The second order equation also needs correction for diameter, density, pipe line working temperature and fluid compressibility. This correction equation can be given by; XV r2 p2^R Lv2[dN0MINAL| f PACTUAL YTACTUAL Y. L_ 1 2 I dACTUAL J t 0.84 A 283 A 450 In the third part of this thesis the equations that introduced in the literature are compared to Darcy-Weisbach equation which is based on TS 7363 and TS 6565. In the literature there are many pressure loss equations which based on some simplicity for obtaining friction factors. Some of them (e.g. Weymouth, Spitzglass) introduced a constant friction factors for all Reynolds number. Therefore they do not work in laminar regime, hydraulically smooth regime and transition regime. They are similar to von Karman 's fully rough turbulent flow and as we know that they are not valid behind Rouse limit. Some others introduced a linearly decreasing friction factors line on the log-log paper. This gives better results compared to other equations for all Reynolds numbers. Although they deviate from real friction factors, they were commonly used when computer were not available. Some of these equations were introduced by Renouard. These equations are advised by İGDAŞ and the origin of the equation probably comes from French literature. The reason of this advice may be due to the co-operative of French SofreGas and İGDAŞ. Renouard has introduced four different equations. These equations are used for four different states. We denote these equations as Renouard 1, Renouard2, Renouard3 and Renouard4. Renouard 1 equation is; AP = 23300/1 vli /4.8 advised to be used for low pressure and low flow rate. Renouard calculates friction effects by decreasing power of diameter and flow rate. Renouard offers a second equation as follows; AP = 23200/1 v182 t.82 This one is for medium flow rate and low pressure which actually has a different friction factor. Renouard3 equation has same friction factor with Renouard2; P*-P?=4S.6*\06yL 1.82 V.74.82 So that both of them have same power values which is shown in chapter 4. This equation should be used for medium flow rate and medium pressure. Renouard4 is for high flow rate and high pressure and is given by; xvi P?-P?=22A*\06yLV d 1.96 4.96 Renouard4 has also a different friction factor equation. These three friction factors give decreasing linear behaviour on the log-log paper. After evaluations it can be concluded that Renouard equations give better performance for low flow rates. In other words, Renouard equations give much better results for Reynolds number around 4000. They show higher deviation with increasing flow rate and Reynolds number. Second, Weymouth equation is studied. This equation is assumed to be appropriate for medium and high pressure as stated in the literature. This equation can be converted into TS 7363 units as follows; (p2-P2)=1.12*l(T8pL v2 1 " «T For this equation Weymouth assumed a constant friction factor value in fully rough turbulent flow regime. In this regime, von Karman and Colebrook equations have lower friction factors value. In the other regimes, Weymouth friction equation has less friction value. When compared to Darcy - Weisbach, Weymouth equation gives fairly consistent results. Actually Weymouth equation is derived from energy balance and it contains some small errors due to the simplification of friction effects. The third equation that is investigated and compared to Darcy - Weisbach equation is Panhandle equation. Panhandle introduced two different equations. Panhandle A equation which is in T S 7363 units, (p2-P2) = 6.1*l(T8£- _ d48541 This equation is for low pressure and relatively short pipes. As it can be seen that this relation is similar to Renouard3 equation and gives close results to it. But like Renouard 3, Panhandle A equation generally produces less pressure loss compare to Darcy - Weisbach equation. Panhandle B equation which is for high pressure and long pipe, as follows, (p.2-p2) = i.54*i(r8-£- "^, \ 1 2> £ j4.961 This equations gives similar results of Renouard 4. Panhandle defined an efficiency index that should be obtained experimentally for correction.
Description: Tez (Yüksek Lisans) -- İstanbul Teknik Üniversitesi, Fen Bilimleri Enstitüsü, 1995
Thesis (M.Sc.) -- İstanbul Technical University, Institute of Science and Technology, 1995
URI: http://hdl.handle.net/11527/17033
Appears in Collections:Petrol ve Doğal Gaz Mühendisliği Lisansüstü Programı - Yüksek Lisans

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