Advances in Engineering Research (AER), volume Global Conference on Mechanics and Civil Engineering (GCMCE 2017)

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1 Advances in Engineering Research (AER), volume 2017 Global Conference on Mechanics and Civil Engineering (GCMCE 2017) Comparaive Analysis of Esimaion Formula of Acid Dew Poin for Differen Flue Gas Jinhui Song1,a, Jiahu Li2,b, Hui Yuan2,c,*, Zhongqiang Ren2,d 1Guangdong 2 School Elecric Power Research Insiue Energy echnologies Ld of energy and power engineering, Norh China Elecric Power Universiy, Baoding, Hebei, China asongjinghui200@1.com, b79552@qq.com, c52@qq.com, d19270@qq.com *Corresponding auhor Keywords: acid dew poin, esimae, analysis Absrac. Acid dew poin is one of he imporan parameers in boiler design and operaion. Is heigh is closely relaed o he flue gas emperaure, boiler efficiency, coal consumpion and he uilizaion of flue gas wase hea a he ail of he boiler. In his paper, from he poin of view of he sulfur conen of coal, he concenraion of SO and he conen of waer vapor afer burning, he common acid dew poin esimaion formula is used o esimae he corresponding acid dew poin value, and he resuls are analyzed. The resuls show ha he acid dew poin and sulfur conen coal, coal combusion and SO concenraions of waer vapor basic relaed, compared wih he formula, formula for esimaion of he error is small, he former Sovie Union of he empirical formula of acid dew poin value is low. Inroducion Coal-fired boiler fuel conains a cerain amoun of sulfur, The flue gas by fuel combusion generaed conains a cerain amoun of SO2, SO and waer vapor. Under normal circumsances, coal-fired boiler flue gas SO volume of abou 1~50ppm. When he emperaure of flue gas is lower han 200, SO and waer vapor ha in he flue gas condense ino H2SO seam and H2SO seam, race of H2SO seam makes he dew poin emperaure of flue gas significanly increased. According o he sudy shows ha he exhaus gas emperaure increased by 15~20, he boiler hermal efficiency reduced by abou 1%, if he exhaus emperaure is oo low, i will cause he heaing meal surface corrosion and affec he normal working of boiler. In order o avoid effecively he low emperaure corrosion of he boiler, he economic exhaus gas emperaure of he boiler should be kep wihin a cerain range of he dew poin of he flue gas. Therefore, he flue gas dew poin emperaure is prediced o reduce he low emperaure corrosion and improve he boiler hermal efficiency has imporan pracical significance. In recen years, some scholars have begun o sudy he esimaion model abou acid dew poin. Differen acid dew poin esimaion models are proposed from differen angles. These acid dew poin esimaion models have advanages and disadvanages. Each of he esimaed models has differen levels of acid dew poin due o he differen facors considered. Some scholars have compared and analyzed hese esimaion models, bu did no consider he effec of he change of coal ype and he conen of coal componens on he esimaion of acid dew poin. In his paper, he esimaion model is evaluaed in he case of coal. There are also some scholars sar o sudy he influence of fly ash on acid dew poin and make explanaion for he low value of acid dew poin in acual operaion. The esimaion of flue gas acid dew poin he esimaion formula abou flue gas acid dew poin So far, many expers and scholars have done a lo of research on he esimaion of acid dew poin. Which can be divided ino wo caegories: one is based on he Sovie Union and domesic scholars as he represenaive of a large number of power plan boiler uni based on he acual operaion Copyrigh 2017, he Auhors. Published by Alanis Press. This is an open access aricle under he CC BY-NC license (hp://creaivecommons.org/licenses/by-nc/.0/). 05

2 Advances in Engineering Research (AER), volume experience summed up he acid dew poin empirical calculaion model; he oher is Wesern scholars as represenaive, based on acid dew poin and The hermodynamic relaions beween he influencing facors and he semi- heoreical calculaion model of experimenal daa were esablished. The firs kind of research mehod is adapable according o a large number of field experience daa, bu i can reveal heoreically he relaionship beween acid dew poin and is influencing facors. The second ype of research mehod is mainly hrough he hermodynamic heoreical relaionship and experimenal daa fi ino acid dew poin calculaion model.alhough is adapabiliy is no as good as he firs mehod, bu can reveal heoreically he relaionship beween acid dew poin and is influencing facors, and hus more and more recognized by scholars [1]. These wo ypes of esimaes are shown in Table1. Table 1 Acid Dew Poin Esimaion Formula source Acid dew poin esimaed formula Explanaion [2] Former Sovie Union [] Halsead Curve [] V lgvso lg SO ld S 1.05 ar, red h A ar, red [2] lgvh lg 2 2SO V H2SO Verhoff&ranchero P lg PSO 27.1lg PH 1.0 lg 2O SO lg P lg P Japan Elecric Power Indusry Cener [] Conains experimenal consans [] Haase and Borgmann [] [] Li Pengfei 0.29 lg PSO lg P lg P Taking ino accoun he impac of fly ash on acid dew poin, widely used in China SO 0.27 lg PSO lg P lg 20 lgv a SO n ld BPH 2SO lg PSO 1.7 lg P 1 2 lg SO 20 lg ld 1.1 S 1.05 ar, red h A ar, red Can be used as an evaluaion crierion for oher esimaion formulas P SO formula A [5] formula B [5] Widely used in Japan n ld.2s ar, red Xie Tian In addiion o he above-menioned more recognized esimaes, foreign scholars have proposed oher hermodynamic mehods for calculaing acid dew poins. I includes numerical analysis, neural nework and so on. For example, Bahadori proposed a dew poin predicion ool based on he Van der Mundle deerminan, which akes ino accoun facors such as fuel ype, SO concenraion, and excess air coefficien. ZareNezhad e al. on he basis of a large number of acual addiions o he above-menioned more recognized esimaes, foreign scholars have proposed oher mehods of calculaing he acid dew poin of hermodynamics. I includes numerical analysis, neural nework and so on. For example, Bahadori proposed a dew poin predicion ool based on he Van der Mundle, which akes ino accoun facors such as fuel ype, SO concenraion and excess air coefficien.zarenezhad e al. Proposed a simulaed neural nework model o predic acid dew poin based on a large number of 0

3 Advances in Engineering Research (AER), volume acual operaing daa. Bu hese mehods have some limiaions, and he need for some acual operaing daa. Such as SO concenraion and waer vapor concenraion, ec. can no be obained accuraely. Analysis of Esimaion Formula of Acid Dew Poin for Flue Gas In his paper, eigh kinds of acid dew poin esimaion mehods are used o calculae he acid dew poin values of en kinds of ypical coal (see Table 2) wih differen sulfur conen. Table 2 sulfur conen of coal and combusion afer flue gas SO concenraion and waer vapor conen value Acid dew poin emperaure/( ) kind of coal Fengguang lignie Jiaozuo anhracie Longfeng washed coal Jinzhu Mounain anhracie Huainan biuminous coal Kailuan biuminous coal Yuanbaoshan lignie Fuxin biuminous coal Xuzhou biuminous coal Xishan lean coal Sulfur conen (%) SO conen ppm Waer vapor conen % Former Sovie Union Halsead curve Japan Elecric Power Indusry Cener Sulfur conen/ % Fig.1 Curve of sulfur conen in coal combusion on acid dew poin The formula proposed by Duch scholar is obained by he regression of he Muller curve. The equaion akes ino accoun boh he influence of waer vapor and he influence of SO, and he calculaed acid dew poin daa and he parameers of carbon, sulfur and excess air of he Mohr calculaion, he difference beween he wo is less han 1.5, is recognized as accuracy crieria of evaluaion of oher acid dew poin esimaion mehod. Fig.1 shows he effec of sulfur conen on he acid dew poin. I can be seen from he figure ha wih he change of sulfur conen in coal, he change rend of acid dew poin value obained from he esimaion formula of all acid dew is roughly he same. When he sulfur conen was less han 0.%, he sulfur conen was posiively correlaed wih he acid dew poin value. Because wih he increase of he sulfur conen of coal, he concenraion of SO produced afer combusion increases firs and hen increases. When he sulfur conen is more han 0.%, he sulfur conen is posiively correlaed wih he acid dew poin value. This is also because he concenraion of SO in he flue showing he rend of increase firs and hen decrease. Compared wih he formula curve, he Halsead curve, he former Sovie empirical formula and he Haase & Borgmann formula have he greaes error. Among hem, Halsead curve in he sulfur conen is low, he maximum error up o 19%.he esimaes formula of Japan Elecric Power Insiue, formula and formula curve error is relaively small, he maximum error occurs in he coal when he sulfur conen is high. The former Sovie Union empirical formula and he 07

4 Advances in Engineering Research (AER), volume formula esimae he acid dew poin is low.however, i is found from Fig. 1 ha he law of change of he acid dew poin wih he change of he sulfur conen of he coal is no obvious And i is no comprehensive o deermine wheher he accuracy of each esimaion formula is only by comparing he change rend of he acid dew poin wih he sulfur conen in he coal.therefore, his paper also analyzes he accuracy of each esimaion formula from he wo facors ha influence he acid dew poin of SO concenraion and waer vapor conen. Former Sovie Union Halsead curve Japan Elecric Power Indusry Cener Acid dew poin emperaure/( ) SO concenraion/(ppm) Acid dew poin emperaure/( ) Fig.2 Curve of SO concenraion on acid dew poin when waer vapor conen is 9% Former Sovie Union Halsead curve Japan Elecric Power Indusry Cener 2 SO concenraion/(ppm) Fig. Curve of SO concenraion on acid dew poin afer en kinds of coal combusion Fig.2 shows he effec of SO concenraion on he acid dew poin when he waer vapor conen is 9%. I can be seen from he figure,wih he increase of SO concenraion, he change rend of acid dew poin is he same.when he SO concenraion is less han.5ppm, he acid dew poin value is posiively correlaed wih he SO concenraion and he increase rae is more faser. When he concenraion of SO is more han.5ppm, he acid dew poin value is posiively correlaed wih SO concenraion bu he increase rae is slow. Compared wih he curve, he error of he former Sovie empirical formula and he is he larges, and he former Sovie empirical formula has a maximum error of 5% a low concenraion. The Verhoff & Branchero formula has less error han he formula curve. This comparison is only from he conen of waer vapor keep consan o analyze he accuracy of he formula, bu aking ino accoun he acual siuaion in he power plan every day o burn differen ypes of coal flue gas waer conen is changing,therefore,he calculaed SO concenraion and he corresponding acid dew poin values of he en kinds of coal combusion in his paper are used o analyze he change rend of acid dew poin wih SO concenraion in he acual operaion. Fig. shows he influence of SO concenraion on acid dew poin afer en coal combusion. I can be seen from he figure ha he acid dew poin has a posiive correlaion wih he SO concenraion in he flue gas afer coal combusion bu increase slowly. Alhough he conen of waer vapor ha generaed by he differen ypes of coal burning afer is differen, increasing he concenraion of SO in he flue gas so ha he parial pressure is increased ha leads acid dew poin also increase. Compared wih he formula, he Halsead curve and he Haase & Borgmann formula have a large error of up o 20%. Japan Elecric Power Research Insiue esimaes, formula error is small. The empirical formula of he former Sovie Union 0

5 Advances in Engineering Research (AER), volume and he Haass & Borgmann formula are low. s calculae he acid dew poin value is high. By comparing Fig. 2 and Fig., he acid dew poin value increases as he SO concenraion increases. Former Sovie empirical formula, Haass & Borgmann formula and formula s acid dew poin value is low. Japan Elecric Power Research Insiue esimaed formula and Verhoff & Branchero esimaed formula on he Acid dew poin value is high. The former Sovie Union empirical formula on he calculaed value of acid dew poin is lowes, because i is a large number of measured daa from he power saion and ake ino accoun he impac of fly ash on acid dew poin, so i is closer wih he acual value of acid dew poin. 170 Former Sovie Union Halsead curve Japan Elecric Power Indusry Cener Acid dew poin emperaure/( ) SO concenraion/(ppm) Acid dew poin emperaure/( ) Fig. Effec of waer vapor conen on acid dew poin when SO concenraion is ppm Former Sovie Union Halsead curve Japan Elecric Power Indusry Cener 1 Flue gas conen of seam / (%) Fig.5 Curve of waer vapor concenraion on acid dew poin afer en kinds of coal combusion Fig. shows he effec of waer vapor conen on he acid dew poin a SO concenraion is ppm. Due o he, he Halsead curve does no ake ino accoun he effecs of waer vapor, and he acid dew poin does no change when he conen of waer vapor changes. Wih he increase of conen of waer vapor, he acid dew poin calculaed by each esimaion formula showed he same rend wih he increase of waer vapor conen. When he conen of waer vapor is less han 11%, he conen of waer vapor is posiively correlaed wih he acid dew poin and grows faser. When he waer vapor conen is greaer han 11%, he acid dew poin rises slowly. Compared wih he formula, he Japan Elecric Power Research Insiue esimaed he formula, Verhoff & Branchero esimaed he calculaed value is high and he ohers are low. The conen of waer vapor in he flue gas and he corresponding acid dew poin values were calculaed in his paper. So as o sudy he change rend of acid dew poin wih he increase of waer vapor conen when SO concenraion is differen. Fig. 5 shows he influence of he concenraion of waer vapor on he acid dew poin afer en coal combusion. As can be seen from he figure, wih he increase in he percenage of waer vapor in he flue gas, all he acid dew poin esimaed formula calculaed from he acid dew poin value of he rend is roughly he same. When he conen of waer vapor is less han.5%, The relaionship 09

6 Advances in Engineering Research (AER), volume beween he acid dew poin and he percenage of waer vapor is firs posiive and hen negaively correlaed, which is because he concenraion of SO in flue gas increases firs and hen decreases, and he concenraion of sulfuric acid increases firs and hen decreases. When he conen of waer vapor is more han.5%, he acid dew poin is firs posiive and hen negaively correlaed wih he percenage of waer vapor, which is also due o he concenraion of SO in flue gas increases firs, hen decreases and hen increases.compared wih he formula curve, Halsead curve, Haase and Borgmann are he mos error. Among hem, he Halsead curve has a higher error in high conen of waer vapor, up o %. И. A.Bapahoba formula, he former Sovie Union, Haase and Borgmann empirical formula s esimaed value is low. Compared wih Fig. and Fig. 5, he rend of he heoreical calculaion is differen from ha of he en kinds of coal calculaed by he increase of he conen of waer vapor. The former se he concenraion of SO in he flue gas as he fixed value, while he laer he concenraion of SO increased firs, hen decreased and hen increased.compared wih he formula, he esimae of he acid dew poin of he formula is close o ha. The former Sovie Union empirical formula is low. Conclusion (1) From he analysis of he sulfur conen of coal, we can see ha he esimaed formula of Japan Elecric Power Research Insiue, formula and formula curve error is relaively small, he former Sovie Union empirical formula o esimae he acid dew poin is relaively low. (2) Analysis of SO concenraion from flue gas, Compared wih he formula, he.a.bapahoba formula and Verhoff&amp & Branchero formula of acid dew poin calculaion error is small. The acid dew poin value calculaed by he empirical formula of he former Sovie Union is minimum. () From he analysis of he conen of waer vapor in he flue gas, compared wih he formula, he esimaed value of acid dew poin of formula is close wih i. The esimaed value of acid dew poin of he former Sovie empirical formula is he lowes. Acknowledgemens This paper is one of he phased resuls of he research and developmen of low emperaure and low emperaure hea and dus conrol of supercriical boiler (GDKJXM )in China Souhern Power Grid Co., Ld. References [1] Junkai Feng, Youing Shen edior. Boiler heory and calculaion [M]. Beijing: Science Press, 1992: 7-79(in chinese). [2] Ming-sheng Jia,Chang-ming Ling.Facors of Affecing he Flue Gas Acid Dew Poin Temperaure and is Way of Calculaion[J].Indusrial Boilers 200,:1-5(in chinese). [] Junkai Feng, Youing Shen edior. Boiler heory and calculaion [M]. Beijing: Science Press, 1992: 7-79(in chinese). [],Badge B.V.Ge Acid Dew Poin of Flue Gas[J].Hydrocarbon Processing, 197 (7):5-55. [5] Verhoff.F.H,Banchero.J.T.Predicing Dew Poin of Flue Gases [J]. Chem. Eng. Prog, 197, 70(): [] Zhi-Yong Tang, Bao-sheng Jin,Ke-qin Sun e al.he conras and evaluaion of he calculaion formulas of acid dew poin emperaure of he flue gas afer he WFGD [J].Journal of Power Engineering,2005,25(Sup.):1-21(in chinese).