District hating simulation in th aspct of hat supply safty Bożna Babiarz 1,*, Pawł Kut 2 1 Rzszow Univrsity of Tchnology, Faculty of Civil and Environmntal Enginring and Architctur, Poland 2 Rzszow Univrsity of Tchnology, Faculty of Civil and Environmntal Enginring and Architctur, Poland Abstract. District hating systms as stratgic objcts from th point of viw of stat scurity must nsur rliability and scurity in supply of hat to thir customrs [1, 2]. Thanks to computr simulation mthods, district hating companis can analys th opration of th hating ntworks at th dsign and opration stag. Computr simulations also offr a wid rang of possibilitis in th aspct of optimization of th district hating opration as wll as prdiction and analysis of ntwork failur ffcts [3-6]. Th papr concrns th simulation of a district hating ntwork. Th mthods for th simulation of hating ntworks wr charactrizd and simulations of district hating systm wr carrid out. Th ffcts of th failur wr analysd at diffrnt valus of outsid tmpraturs and for diffrnt durations of failur. Th valu of compnsation for undlivrd hat was also dtrmind. Simulations wr carrid out for an actual district hating systm locatd in Rzszow. 1 Introduction A district hating systm is a st of dvics usd for hat nrgy transport through th piplins from th hat sourc to th customrs through a hat mdium, which is most oftn watr or stam. According to data from th Enrgy Rgulatory Offic, th total thrmal powr installd by licnsd hat producrs in 2016 was 54 259.8 MW, and th availabl powr 53 434.7 MW [7]. Among th hat sourcs, thr ar mostly small sourcs with a capacity of up to 50 MW (58.1% in 2016). Only 10 companis had a thrmal powr xcding 1 000 MW. Th lngth of th hating ntwork availabl to licnsd hating companis amountd to 20 744.9 km, including hating ntworks conncting sourcs with district hating substations and low-paramtr ntworks [7]. Hating ntworks, as stratgic objcts from th point of viw of th scurity of th stat and its citizns, ar part of th critical infrastructur. Critical infrastructur protction should nsur th continuity of powr supply and th prvntion of thrats [1]. An important lmnt of protction is also th ability of th systm to nutraliz th ffcts of advrs vnts and th possibility of rcovry in th vnt of a failur. In addition to th scurity risks, failurs of hating ntworks can lad to conomic and tchnical losss. * Corrsponding author: bbabiarz@prz.du.pl Th Authors, publishd by EDP Scincs. This is an opn accss articl distributd undr th trms of th Crativ Commons Attribution Licns 4.0 (http://crativcommons.org/licnss/by/4.0/).
Th opration of hating ntworks should b carrid out in a tchnical and conomically justifid way, with th rduction of nrgy consumption and th minimization of transmission losss. Th production and transmission of thrmal nrgy may b a sourc of nvironmntal pollution, thrfor th opration of th systm should b carrid out in a way that taks into account nvironmntal protction [8]. In th opration procss, th systm s rsistanc to scurity thrats to th hat supply is important, as th ability to rgnrat aftr disturbancs or a ngativ vnt [9-12]. Computr simulations of hating ntworks mak it possibl to analyz ntwork opration without having to physically intrfr with thir structur. Thanks to th us of computr modls, th ntwork can b analysd in th vnt of failur, xtnsion and connction of nw hat sourcs and nw customrs. Simulation modls giv an opportunity to optimiz th opration of th hating ntwork [4,11], thanks to which th ntwork bhaviour in cas of an mrgncy situation can b prdictd at th dsign stag. 2 Thortical basis for th simulation of hating ntworks Computr simulations mak it possibl to rcrat a givn phnomnon basd on mathmatical modls [3, 5, 6, 10]. In th cas of a systm in which variabls ar not a function of tim, static modls ar built, dscribd by algbraic quations. For a stationary flow of hot watr in th piplins, th mathmatical modls ar a non-linar algbraic quation. This modl dscribs th rlations btwn prssur drop, flow, gomtric dimnsions of piplins, proprtis of piplins and hot watr. Static simulations of th hating ntwork ar dvlopd on th basis of Kirchhoff s first and scond law and flow quations. According to Kirchhoff s first law, th algbraic sum of flows in ach nod of th hating ntwork is zro. Th nods of th ntwork ar points whr thr or mor piplins mt, hat consumption or dlivry to th grid, pumps, valvs, tc. installd. For ach nod, th quation rsulting from Kirchhoff s first law can b writtn as [3]: n i 1 m m (1) whr: α factor including th way of conncting th lmnt to th nod: α = 1 whn th flow dirction is to th nod, α = -1 whn th flow dirction is from th nod, α = 0 whn thr is no connction to th nod, ṁ flow rat in th lmnt, ṁ i flow rat in th nod. According to th Kirchhoff s scond law, th algbraic sum of prssur drops in s givn loop is zro. For ach loop, th quation rsulting from Kirchhoff s scond law can b writtn as [3]: n i 1 i p 0 (2) whr: β factor qual: β = 1 whn th lmnt blongs to th loop and is consistnt with it positiv dirction, β = -1 whn th lmnt blongs to th loop and is consistnt with its opposit dirction, β = 0 whn th lmnt dos not blong to th loop, Δp prssur drop. Bcaus in Kirchhoff s first law, th mass flow rat ar indpndnt variabls, and th quantity of prssur drops in Kirchhoff s scond law, it is ncssary to dtrmin th rlations btwn thm. For th loop mthod it can b writtn as [3]: 2
p f( m ) (3) For th nodal mthod [3]: m g p ) (4) ( From th point of viw of th amount of data ndd for calculations, simulations basd on static modls ar lss dmanding than dynamic modls, which ar built using diffrntial quations. Dynamic modls ar usd whn th systm has variabls that ar a function of tim. 3 Simulation analysis of th scurity of hat supply to rcipints 3.1 Mthodology Th scurity of hat supply in th Enrgy Law [13] is dtrmind by th systm s ability to nsur ntwork scurity and to balanc nrgy supply with dmand. Providing it with nrgy scurity and th safty of popl is th main task of hating companis. Th simulations wr carrid out using th EC.GIS softwar (Enrgtyka Ciplna Gographic Information Systm) [14], dvlopd by Globma. EC.GIS softwar allows hating companis to manag ntwork assts, rcord data, maintain traffic, opration, planning invstmnts and carry out simulations of hating ntworks in normal oprating conditions and in mrgncy situations. For simulatd cass of ntwork failurs, th valus of allowanc rlatd to undlivrd hat wr dtrmind in accordanc with th tariff rgulation [15]. Allowancs can b prsntd in th form of functions rlatd to th limitation of hat supply and thrmal powr dlivrd to rcipints and can b prsntd in th form of functions of svral variabls [1]: S F(, t, x, ) (5) u n i i whr: n ordrd thrmal powr at th rcipint n, t i duration of th hating powr limit, x i prcnt of th hating powr supply limit, dsign tmpratur of th outsid air, adoptd dpnding on th climat zon of th location of th objct supplid with hat. If th nrgy companis fail to mt th quality standards of customr srvic, th hat output will b limitd (unlss th hat sal contract stats othrwis), th rcipints will b ntitld to an allowanc [15], th amount of which is calculatd as follows: if th thrmal powr limit is up to 40%, th amount of th allowanc is calculatd according to th formulas: S S S (6) u40 um40 uc40 Sum40 0,25 ( t r) 3,6 24 Cn hp :365 (7) Suc40 0, 4 ( t r) 3,6 24 hp Cc (8) if th thrmal powr limit is abov 40%, th amount of allowanc is calculatd according to th formulas: S S S (9) u40u um40u uc40u 3
Sum40 0,5 ( t r) Cn hp :365 (10) Suc40u 0,8 ( t r) 3,6 24 hp Cc (11) whr: S u total allowanc for limitation in th hat supply, S um allowanc for rducing thrmal powr, S uc allowanc for undlivrd hat, t thrmal powr dtrmind basd on th calculatd flow rat and hat carrir paramtrs spcifid in th rgulatory tabl[mw], r actual thrmal powr, dtrmind basd on th flow rat and th actual hat carrir paramtrs [MW], 24 multiplir, 24 hours a day [h], h p th numbr of days whn thr wr limitations in th supply of hat causd by th nrgy company s failur to mt th quality standards of customr srvic, C n pric for ordrd thrmal powr for a givn tariff group [PLN/MW], C c hat pric for a givn tariff group [PLN/GJ]. 3.2 Cas study Simulations wr carrid out for th actual hating ntwork of Rzszow, managd by th Municipal Hat Supply Company [14]. Two thrmolctric powr plants ar th sourc of thrmal nrgy: Rzszow Powr Station, a branch of PGE Mining and Convntional Enrgy S.A., which covrs about 80% of th city s dmand for thrmal nrgy and th Fnic Thrmolctric Powr Plant covring th rmaining 20%. Th Rzszow district hating systm is a ring systm. Two slctd failurs of th hating ntwork wr analyzd. Fig. 1 shows th xact location of th first analyzd damag of th hating ntwork. Th failur is locatd at th Rzszow Univrsity of Tchnology at Poznanska St. Th piplin mad with traditional tchnology has faild. Fig. 1. Location of th first failur. Th rsults of th first failur simulation ar shown in tabl 1. As a rsult of damag th piplin in th plac markd in Fig. 1 part of th ntwork with a lngth of 1030.53 m was xcludd. Failur causd th cutting off of 5 rcipints, quippd with 26 hat substations, including 21 hat substations locatd in Rzszow Univrsity of Tchnology. Th total thrmal powr ordrd in wintr by disconnctd rcipints was 5.64 MW. 4
Tabl 1. Rsults of ntwork failur simulation at th Rzszow Univrsity of Tchnology. Paramtr Valu Lnght of piplins in th sparatd ntwork [m] 1030.53 Diamtr of th damagd piplin [mm] 400 Numbr of disconnctd hat substations 26 Numbr of disconnctd rcipints: 5 Total wintr thrmal powr [MW] 3.70 Tabl 2 shows th capacity of th sparatd ntwork and th tim of filling th sparatd sction of th ntwork aftr rpairing th damag. Tabl 2. Capacity of th sparatd ntwork and filling tim. Paramtr Valu Sparatd ntwork capacity [m 3 ] 242.13 Filling spd [m 3 /h] 30 Filling tim [h] 8.15 Failur of th hating ntwork at th analyzd point ld to total cut-off th Rzszow Univrsity of Tchnology and fiv othr rcipints from th thrmal nrgy supply. It was not possibl to provid hat to th rcipints during th rpair tim. Th filling tim of th sparatd ntwork aftr damag rpair was 8 hours and 4 minuts with a filling spd of 30 m 3 /h. Fig. 2 shows th amount of undlivrd hat dpnding on th duration of th failur for diffrnt xtrnal tmpraturs. Fig. 2. Rlationship btwn undlivrd hat and failur duration. As th tmpratur riss, th amount of undlivrd hat dcrass. At a tmpratur of -20ºC, th amount of undlivrd hat for a failur lasting 5 days was almost 2500 GJ, and for a tmpratur of 10ºC it was 1083 GJ. Fig. 3 shows th location of th scond analyzd hating ntwork failur. Th scond failur involvs a part of th ntwork, mad from pr-insulatd pips, cutting through Lukasz Ciplinski St. nar Galria Rzszow. 5
Fig. 3. Location of th scond failur. Th rsults of th scond failur simulation ar shown in tabl 3. In th cas of th scond failur, th lngth of th xcludd piplins was 347.82 m. Failur causd th cutting off of 1 rcipint with 1 hat substation, which is Galria Rzszow. Th total thrmal powr ordrd in wintr by th disconnctd rcipint was 3.16 MW. Tabl 3. Rsults of ntwork failur simulation nar Galria Rzszow. Paramtr Valu Lnght of piplins in th sparatd ntwork [m] 347.82 Diamtr of th damagd piplin [mm] 200 Numbr of disconnctd hat substations 1 Numbr of disconnctd rcipints: 1 Total wintr thrmal powr [MW] 2.74 Tabl 4 shows th capacity of th sparatd ntwork and th tim of filling th sparatd sction of th ntwork aftr rpairing th damag. In th cas of th scond failur, th filling tim of th ntwork, du to smallr capacity compard to th first failur amountd to 46 minuts. Tabl 4. Capacity of th sparatd ntwork and filling tim. Paramtr Valu Sparatd ntwork capacity [m 3 ] 23,22 Filling spd [m 3 /h] 30 Filling tim [h] 0,77 For buildings locatd nar Galria Rzszow, which wr supplid with th sam piplin, thanks to th us of a ring ntwork in th district hating systm, thrmal nrgy was dlivrd from a diffrnt dirction. Fig. 4 shows th amount of undlivrd hat dpnding on th duration of th scond failur. Simulations wr carrid out for th sam xtrnal tmpratur valus as for th first failur. 6
Fig. 4. Rlationship btwn undlivrd hat and failur duration. For th scond failur, as in th cas of th first failur, th rlationship btwn undlivrd hat and failur duration is linar. In th cas of a failur lasting 5 days, th amount of undlivrd hat was 1 365 GJ for th xtrnal tmpratur of -20ºC, and 1 060 GJ for th tmpratur of 10ºC. It can b noticd that in th cas of th scond failur, diffrncs in th amount of undlivrd hat dpnding on th xtrnal tmpratur ar smallr than for th first failur. For th analyzd failurs, allowancs for th undlivrd hat wr calculatd. Calculations wr mad for thrmal nrgy prics, dtrmind by th Municipal Hat Supply Company. Th pric for ordrd thrmal powr is 2 292.92 PLN/MW and th hat pric is 14.96 PLN/GJ. Fig. 5 shows th rlation btwn th allowancs for undlivrd hat and failur duration. Aftr 5 days, th allowancs rsulting from th first accidnt would amount to 29 159.79 PLN, and for scond failur 16 337.76 PLN. Fig. 5. Rlationship btwn allowanc for undlivrd hat and failur duration. 4 Summary Simulations of th hating ntwork allow possibilitis for assssing th opration of th systm in various scnarios of vnts rlatd to th risk of a lack of hat supply. Th us of th Gographic Information Systm (GIS) allows hating systm oprators quick accss to documntation and th ability to rduc th numbr of fild inspctions and rlatd costs. Ntwork simulation in conditions of damag allows th opportunity to assss th systm 7
from th point of viw of th safty of hat supply to rcipints. Prformd simulations of mrgncis in th hating ntwork shows what th ffcts and xtnt of damag to th piplins can b. Failurs can lad to th intrruption of hat supply to consumrs, which may pos a thrat to human halth or lif. Damag to piplins supplying a grat amount of customrs with significant ordrd powr also lads to high conomic losss that may affct both consumrs and hating companis. This typ of analysis can b hlpful for hating companis in managing th systm in th aspct of caring for rsilinc to thrats, optimizing ntwork opration as wll as assssing th risk of a lack of hat supply to rcipints bing a masur of scurity loss. Rfrncs 1. B. Babiarz, Nizawodność i bzpiczństwo systmów zaopatrznia w cipło, Oficyna Wydawnicza Politchniki Rzszowskij, Rzszów (2017) 2. B. Babiarz, Hat supply systm rliability managmnt [w:] Safty and Rliability. Mthodology and Applications, (pod rd.) Tomasz Nowakowski i in., TAYLOR & FRANCIS GROUP p. 513-520. London (2015) 3. P. Malinowski, Cipłownictwo, Ogrzwnictwo, Wntylacja 5, (2005) 4. M. Vstrlund, J. Dahl, Enrgy convrsion and Managmnt p. 555-567, 122, (2016) 5. I. Dl Hoyo Arc, S. Hrrro Lópz, S. Lópz Prz, M. Rämä, K. Klobut, J.A. Fbrs, Rnwabl and Sustainabl Enrgy Rviws p. 1863-1873.82, (2018) 6. M. Vstrlund, A. Toffolo, J. Dahl, Enrgy Convrsion and Managmnt, p: 63-73, 122, (2016) 7. Enrgtyka ciplna w liczbach 2016. Urząd Rgulacji Enrgtyki, sirpiń (2017) 8. K. Nowak, M. Bukowska, D. Proszak-Miąsik, S. Rabczak, Emission of Air Pollutants in th Hot Watr Production. Iop Conf Sr-Mat Sci., 245, (2017) 9. B. Babiarz, Rsilinc to hazards in district hating systms [w:] Safty and Rliability of Complx Enginrd Systms, (pod rd.) Luca Podofillini, Bruno Sudrt, Božidar Stojadinovic,Enrico Zio & Wolfgang Krögr s.2525-2531, London, (2015 CRC Prss/Balkma) 10. G. Crino Abdin, F. Frschi, at all, District Hating Safty Issus: Intractions Btwn Grounding Systms and Thrmal Installations. IEEE Transactions on Industry Applications, vol. 52, no. 3, May/Jun (2016) 11. M. Lśko, W. Bujalski, Modling of district hating ntworks for th purpos of oprational optimization with thrmal nrgy storag. Archivs of thrmodynamics, vol. 38, no.4, p:139-163 (2017) 12. A. Cugno, M. Nuossan, G. Crino Abdin, A. Poggio, Bultinul AGIR nr 3 (2012) 13. Th Act of 10 April 1997 on th Enrgy Law. Journal of Laws No. 54, itm. 384, as amndd. 14. Matrial shard in Municipal Hat Supply Company in Rzszow 15. Rozporządzni Ministra Gospodarki z dnia 17 wrzśnia 2010 r. w sprawi szczgółowych zasad kształtowania i kalkulacji taryf oraz rozliczń z tytułu zaopatrznia w cipło (Dz.U. Nr 194, poz. 1291). 8