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一、摘要

為支撐可再(zai)生(sheng)能(neng)(neng)源大(da)(da)比(bi)例接(jie)入(ru)新型電(dian)力(li)系(xi)統(tong)(tong)(tong)，大(da)(da)幅提(ti)升(sheng)燃煤機(ji)組靈(ling)活(huo)性(xing)，該(gai)文提(ti)出(chu)耦合(he)燃煤機(ji)組的熔(rong)(rong)(rong)鹽(yan)(yan)(yan)(yan)(yan)(yan)儲能(neng)(neng)系(xi)統(tong)(tong)(tong)并(bing)進行熔(rong)(rong)(rong)鹽(yan)(yan)(yan)(yan)(yan)(yan)工質篩選。針對(dui)(dui)350MW靈(ling)活(huo)燃煤機(ji)組，熔(rong)(rong)(rong)鹽(yan)(yan)(yan)(yan)(yan)(yan)儲能(neng)(neng)系(xi)統(tong)(tong)(tong)承擔3%Pe/min升(sheng)負荷(he)速率(lv)(lv)目標下(xia)，綜合(he)汽(qi)輪機(ji)熱(re)(re)力(li)與關鍵設備傳(chuan)熱(re)(re)分析，從熔(rong)(rong)(rong)鹽(yan)(yan)(yan)(yan)(yan)(yan)基本物性(xing)出(chu)發(fa)(fa)，重點研(yan)究了二(er)元(yuan)(yuan)鹽(yan)(yan)(yan)(yan)(yan)(yan)(60%NaNO3+40%KNO3)和三元(yuan)(yuan)鹽(yan)(yan)(yan)(yan)(yan)(yan)(53%KNO3+40%NaNO2+7%NaNO3)對(dui)(dui)熔(rong)(rong)(rong)鹽(yan)(yan)(yan)(yan)(yan)(yan)蒸(zheng)(zheng)汽(qi)發(fa)(fa)生(sheng)系(xi)統(tong)(tong)(tong)發(fa)(fa)電(dian)效率(lv)(lv)、系(xi)統(tong)(tong)(tong)復雜性(xing)及投資成本的影響。發(fa)(fa)現二(er)元(yuan)(yuan)鹽(yan)(yan)(yan)(yan)(yan)(yan)分解(jie)溫度高，可產生(sheng)較高品位蒸(zheng)(zheng)汽(qi)，熔(rong)(rong)(rong)鹽(yan)(yan)(yan)(yan)(yan)(yan)蒸(zheng)(zheng)汽(qi)發(fa)(fa)生(sheng)系(xi)統(tong)(tong)(tong)的平(ping)均發(fa)(fa)電(dian)效率(lv)(lv)為36.7%，三元(yuan)(yuan)鹽(yan)(yan)(yan)(yan)(yan)(yan)因分解(jie)溫度低，平(ping)均發(fa)(fa)電(dian)效率(lv)(lv)僅為29.2%。與三元(yuan)(yuan)鹽(yan)(yan)(yan)(yan)(yan)(yan)相(xiang)(xiang)比(bi)，二(er)元(yuan)(yuan)鹽(yan)(yan)(yan)(yan)(yan)(yan)熔(rong)(rong)(rong)點高，熔(rong)(rong)(rong)鹽(yan)(yan)(yan)(yan)(yan)(yan)蒸(zheng)(zheng)汽(qi)發(fa)(fa)生(sheng)系(xi)統(tong)(tong)(tong)需(xu)從汽(qi)輪機(ji)抽汽(qi)預熱(re)(re)熔(rong)(rong)(rong)鹽(yan)(yan)(yan)(yan)(yan)(yan)系(xi)統(tong)(tong)(tong)給水，以防止熔(rong)(rong)(rong)鹽(yan)(yan)(yan)(yan)(yan)(yan)凝固堵(du)塞，增加了系(xi)統(tong)(tong)(tong)復雜。采(cai)用(yong)二(er)元(yuan)(yuan)鹽(yan)(yan)(yan)(yan)(yan)(yan)，熔(rong)(rong)(rong)鹽(yan)(yan)(yan)(yan)(yan)(yan)蒸(zheng)(zheng)汽(qi)發(fa)(fa)生(sheng)系(xi)統(tong)(tong)(tong)運行溫度高，在相(xiang)(xiang)同(tong)升(sheng)負荷(he)需(xu)求下(xia)，熔(rong)(rong)(rong)鹽(yan)(yan)(yan)(yan)(yan)(yan)流量、用(yong)量、儲罐(guan)及換熱(re)(re)器(qi)體積均減小，投資成本比(bi)三元(yuan)(yuan)鹽(yan)(yan)(yan)(yan)(yan)(yan)系(xi)統(tong)(tong)(tong)降低1000萬元(yuan)(yuan)。基于本文研(yan)究，建(jian)議采(cai)用(yong)二(er)元(yuan)(yuan)鹽(yan)(yan)(yan)(yan)(yan)(yan)儲能(neng)(neng)系(xi)統(tong)(tong)(tong)，以實(shi)現熔(rong)(rong)(rong)鹽(yan)(yan)(yan)(yan)(yan)(yan)系(xi)統(tong)(tong)(tong)高效性(xing)及安全性(xing)，支撐超(chao)靈(ling)活(huo)燃煤發(fa)(fa)電(dian)。

二、引言

為(wei)支(zhi)撐2030年(nian)碳(tan)達峰和(he)2060年(nian)碳(tan)中和(he)的“雙碳(tan)”目標，我國(guo)未來能(neng)(neng)源(yuan)消(xiao)費增量主要(yao)來自于清潔(jie)能(neng)(neng)源(yuan)，大(da)幅減少化石能(neng)(neng)源(yuan)利(li)用(yong)成為(wei)不可(ke)逆轉的趨勢。太陽能(neng)(neng)、風能(neng)(neng)等可(ke)再生能(neng)(neng)源(yuan)具有間歇(xie)性(xing)、波(bo)動性(xing)，隨著(zhu)大(da)規(gui)(gui)模新能(neng)(neng)源(yuan)發電(dian)(dian)裝機(ji)(ji)(ji)持(chi)續接入電(dian)(dian)網，部分地(di)區新能(neng)(neng)源(yuan)消(xiao)納(na)壓(ya)力凸顯，造成棄風棄光局(ju)面。為(wei)提升電(dian)(dian)力系(xi)統穩定性(xing)，高比(bi)例(li)新能(neng)(neng)源(yuan)電(dian)(dian)力系(xi)統亟需與之(zhi)匹配的靈(ling)(ling)(ling)活(huo)可(ke)調(diao)度資(zi)源(yuan)。目前電(dian)(dian)力系(xi)統的靈(ling)(ling)(ling)活(huo)可(ke)調(diao)度資(zi)源(yuan)主要(yao)包(bao)括燃(ran)氣輪機(ji)(ji)(ji)、抽(chou)水蓄能(neng)(neng)與靈(ling)(ling)(ling)活(huo)煤(mei)(mei)電(dian)(dian)機(ji)(ji)(ji)組等。由于我國(guo)“富(fu)煤(mei)(mei)、貧油、缺氣”的自然資(zi)源(yuan)稟賦，燃(ran)氣輪機(ji)(ji)(ji)不適合在我國(guo)大(da)面積(ji)推廣；抽(chou)水蓄能(neng)(neng)建設周期長(chang)，建設成本較高，且對建造場(chang)地(di)要(yao)求較為(wei)苛(ke)刻，難以短時間內成為(wei)我國(guo)能(neng)(neng)夠提供(gong)大(da)量靈(ling)(ling)(ling)活(huo)性(xing)的發電(dian)(dian)形(xing)式(shi)。2023年(nian)煤(mei)(mei)電(dian)(dian)機(ji)(ji)(ji)組保持(chi)安全高效運行，全年(nian)累計(ji)發電(dian)(dian)5.35萬億千瓦(wa)時，以占全國(guo)52%的裝機(ji)(ji)(ji)規(gui)(gui)模貢獻了占全國(guo)63%的發電(dian)(dian)量，電(dian)(dian)網調(diao)峰仍需要(yao)燃(ran)煤(mei)(mei)機(ji)(ji)(ji)組發揮兜底保供(gong)作(zuo)用(yong)。近(jin)期煤(mei)(mei)電(dian)(dian)不可(ke)能(neng)(neng)大(da)規(gui)(gui)模退役，而是(shi)(shi)逐(zhu)步由提供(gong)電(dian)(dian)力的主體(ti)電(dian)(dian)源(yuan)轉變為(wei)支(zhi)撐性(xing)和(he)調(diao)節性(xing)電(dian)(dian)源(yuan)。因此，煤(mei)(mei)電(dian)(dian)是(shi)(shi)經(jing)濟可(ke)行、安全可(ke)靠的靈(ling)(ling)(ling)活(huo)調(diao)節資(zi)源(yuan)，燃(ran)煤(mei)(mei)機(ji)(ji)(ji)組的靈(ling)(ling)(ling)活(huo)性(xing)改造已為(wei)新能(neng)(neng)源(yuan)消(xiao)納(na)發揮了重要(yao)作(zuo)用(yong)。

燃(ran)(ran)煤(mei)機(ji)組(zu)(zu)的(de)(de)(de)(de)靈(ling)(ling)活性(xing)(xing)(xing)通常是(shi)指運行靈(ling)(ling)活性(xing)(xing)(xing)，即能適應(ying)(ying)(ying)機(ji)組(zu)(zu)出力(li)(li)大幅(fu)波動、快(kuai)速(su)響應(ying)(ying)(ying)各類變(bian)(bian)化(hua)的(de)(de)(de)(de)能力(li)(li)，包括調峰(feng)負(fu)(fu)荷(he)(he)范圍、爬坡速(su)率(lv)(lv)和(he)啟停(ting)(ting)時間等。靈(ling)(ling)活性(xing)(xing)(xing)改(gai)造后(hou)的(de)(de)(de)(de)燃(ran)(ran)煤(mei)機(ji)組(zu)(zu)最低負(fu)(fu)荷(he)(he)達(da)到25%~40%Pe，受(shou)限(xian)于設(she)備安(an)全及可(ke)(ke)靠性(xing)(xing)(xing)，燃(ran)(ran)煤(mei)機(ji)組(zu)(zu)難以實現日啟停(ting)(ting)調峰(feng)。利用燃(ran)(ran)煤(mei)機(ji)組(zu)(zu)參與電(dian)(dian)網調峰(feng)的(de)(de)(de)(de)代(dai)表性(xing)(xing)(xing)國(guo)家，德國(guo)和(he)丹(dan)麥(mai)(mai)已(yi)取得很好的(de)(de)(de)(de)成果，德國(guo)燃(ran)(ran)煤(mei)機(ji)組(zu)(zu)改(gai)造集中于深(shen)度調峰(feng)和(he)快(kuai)速(su)啟停(ting)(ting)能力(li)(li)，變(bian)(bian)負(fu)(fu)荷(he)(he)速(su)率(lv)(lv)達(da)到4%~6%Pe/min。丹(dan)麥(mai)(mai)以熱電(dian)(dian)聯產機(ji)組(zu)(zu)為(wei)主(zhu)，輔(fu)以熱電(dian)(dian)解耦、儲能技術(shu)以及生(sheng)物(wu)質摻燒(shao)等，變(bian)(bian)負(fu)(fu)荷(he)(he)速(su)率(lv)(lv)可(ke)(ke)達(da)到5%Pe/min。此外，歐美(mei)發達(da)國(guo)家燃(ran)(ran)氣資源相對豐富(fu)，電(dian)(dian)網調峰(feng)主(zhu)要依(yi)靠燃(ran)(ran)氣電(dian)(dian)站(zhan)。燃(ran)(ran)氣機(ji)組(zu)(zu)本質靈(ling)(ling)活、變(bian)(bian)負(fu)(fu)荷(he)(he)速(su)率(lv)(lv)可(ke)(ke)達(da)5%Pe/min。為(wei)解決可(ke)(ke)再(zai)生(sheng)能源分鐘(zhong)級(ji)波動發電(dian)(dian)并網帶來的(de)(de)(de)(de)挑(tiao)戰(如圖1所示)，對標(biao)(biao)國(guo)外調峰(feng)機(ji)組(zu)(zu)的(de)(de)(de)(de)變(bian)(bian)負(fu)(fu)荷(he)(he)速(su)率(lv)(lv)，作者所在團隊(dui)聯合多家企業共同申請了能源領域首臺(套)。該首臺套主(zhu)要針對350MW燃(ran)(ran)煤(mei)機(ji)組(zu)(zu)其高負(fu)(fu)荷(he)(he)段(50%~100%THA)具有6%Pe/min的(de)(de)(de)(de)升負(fu)(fu)荷(he)(he)速(su)率(lv)(lv)是(shi)重要指標(biao)(biao)之(zhi)(zhi)一。鍋爐是(shi)制(zhi)約傳統燃(ran)(ran)煤(mei)發電(dian)(dian)機(ji)組(zu)(zu)變(bian)(bian)負(fu)(fu)荷(he)(he)速(su)率(lv)(lv)的(de)(de)(de)(de)關(guan)(guan)鍵之(zhi)(zhi)一，制(zhi)約因素包括：快(kuai)速(su)變(bian)(bian)負(fu)(fu)荷(he)(he)時，工(gong)質溫壓參數快(kuai)速(su)變(bian)(bian)化(hua)導(dao)致厚壁元(yuan)件產生(sheng)較(jiao)大熱應(ying)(ying)(ying)力(li)(li)，影響設(she)備壽命(ming)；鍋爐給粉系統響應(ying)(ying)(ying)跟不上變(bian)(bian)負(fu)(fu)荷(he)(he)速(su)率(lv)(lv)要求，導(dao)致機(ji)組(zu)(zu)響應(ying)(ying)(ying)整體滯后(hou)；鍋爐干濕(shi)態轉換導(dao)致的(de)(de)(de)(de)水(shui)動力(li)(li)不穩(wen)定性(xing)(xing)(xing)加劇，對機(ji)組(zu)(zu)運行安(an)全提出挑(tiao)戰。為(wei)此，作者所在團隊(dui)擬研發柔性(xing)(xing)(xing)水(shui)冷(leng)壁、創新集箱管道連接形(xing)式(shi)等鍋爐關(guan)(guan)鍵技術(shu)，可(ke)(ke)使鍋爐升負(fu)(fu)荷(he)(he)速(su)率(lv)(lv)提升到3%Pe/min(如圖1所示)，但離6%Pe/min的(de)(de)(de)(de)目標(biao)(biao)仍然有較(jiao)大差(cha)距。

近(jin)年來，在國內企業及科(ke)研院所的(de)共同(tong)努力下，我國太(tai)(tai)陽能(neng)熔(rong)(rong)(rong)鹽(yan)(yan)(yan)儲熱(re)發電技術(shu)逐步成熟并達到世界先進水(shui)平(ping)，相(xiang)繼建成了多(duo)個耦(ou)合(he)(he)熔(rong)(rong)(rong)鹽(yan)(yan)(yan)儲熱(re)光熱(re)電站。在太(tai)(tai)陽能(neng)熔(rong)(rong)(rong)鹽(yan)(yan)(yan)儲熱(re)發電技術(shu)基(ji)礎(chu)上(shang)，國內開始研發耦(ou)合(he)(he)熔(rong)(rong)(rong)鹽(yan)(yan)(yan)儲熱(re)的(de)靈活燃煤發電技術(shu)，并取得了較大進展(zhan)。因此，在傳統燃煤機組上(shang)增加熔(rong)(rong)(rong)鹽(yan)(yan)(yan)系(xi)統是(shi)彌補鍋(guo)爐(lu)升負(fu)荷(he)(he)速(su)率(lv)不足的(de)新思路(如(ru)圖(tu)1所示)，即熔(rong)(rong)(rong)鹽(yan)(yan)(yan)系(xi)統通過(guo)熔(rong)(rong)(rong)鹽(yan)(yan)(yan)存儲鍋(guo)爐(lu)部分熱(re)量，在機組需要(yao)快(kuai)速(su)升負(fu)荷(he)(he)時釋放，通過(guo)熔(rong)(rong)(rong)鹽(yan)(yan)(yan)系(xi)統儲放熱(re)完成機組能(neng)量時空(kong)調控。高負(fu)荷(he)(he)放熱(re)階段，熔(rong)(rong)(rong)鹽(yan)(yan)(yan)加熱(re)給(gei)水(shui)產生蒸(zheng)汽，與(yu)鍋(guo)爐(lu)產生的(de)蒸(zheng)汽共同(tong)匯(hui)入汽輪機做功，熔(rong)(rong)(rong)鹽(yan)(yan)(yan)系(xi)統和鍋(guo)爐(lu)分別(bie)貢獻3%Pe/min的(de)升負(fu)荷(he)(he)速(su)率(lv)，機組達到6%Pe/min的(de)升負(fu)荷(he)(he)速(su)率(lv)(如(ru)圖(tu)1所示)。

為確定合理(li)的(de)(de)升(sheng)負(fu)荷(he)區(qu)間(jian)，懷柔實(shi)(shi)驗(yan)室對潤港(gang)電廠#1、2機(ji)，宏業電廠#1、2機(ji)，撫(fu)寧電廠#1、2機(ji)6臺調節性(xing)火電機(ji)組(zu)(zu)進(jin)行(xing)調研，對五個典(dian)型周1萬(wan)多組(zu)(zu)AGC數(shu)據進(jin)行(xing)分析，發現：機(ji)組(zu)(zu)在(zai)50%Pe及(ji)(ji)以上進(jin)行(xing)升(sheng)負(fu)荷(he)的(de)(de)概率(lv)(lv)為74%，升(sheng)負(fu)荷(he)跨度10%~25%Pe的(de)(de)占比最高。因此，綜合考慮熔(rong)(rong)鹽蒸汽(qi)(qi)發生系(xi)統(tong)(tong)設備成本、運行(xing)經(jing)濟性(xing)、液位和壓力控制、產汽(qi)(qi)參數(shu)波動范圍及(ji)(ji)匯(hui)汽(qi)(qi)量對汽(qi)(qi)輪機(ji)的(de)(de)影響。將熔(rong)(rong)鹽系(xi)統(tong)(tong)支撐燃煤(mei)機(ji)組(zu)(zu)升(sheng)負(fu)荷(he)的(de)(de)區(qu)間(jian)定為X→X+25%THA(50%THA≤X≤75%THA)。以75%THA-100%THA升(sheng)負(fu)荷(he)范圍為例(li)，如(ru)圖2所示，為實(shi)(shi)現機(ji)組(zu)(zu)6%Pe/min的(de)(de)升(sheng)負(fu)荷(he)速(su)(su)率(lv)(lv)，鍋爐按(an)3%Pe/min速(su)(su)率(lv)(lv)線性(xing)增加(jia)到機(ji)組(zu)(zu)目標負(fu)荷(he)，熔(rong)(rong)鹽蒸汽(qi)(qi)發生系(xi)統(tong)(tong)以3%Pe/min速(su)(su)率(lv)(lv)升(sheng)到峰值后逐漸降低(di)負(fu)荷(he)退出。

常見的熔鹽(yan)(yan)(yan)由堿金屬、碳酸鹽(yan)(yan)(yan)、硝酸鹽(yan)(yan)(yan)以及磷酸鹽(yan)(yan)(yan)等(deng)(deng)組成。熔鹽(yan)(yan)(yan)在(zai)傳(chuan)熱(re)(re)(re)、儲熱(re)(re)(re)、熱(re)(re)(re)處理(li)、高溫電化學(xue)電鍍和(he)材(cai)料(liao)(liao)加工等(deng)(deng)領域得(de)到廣泛應用，也作為液態燃料(liao)(liao)和(he)儲熱(re)(re)(re)介(jie)質(zhi)應用于飛機/熔鹽(yan)(yan)(yan)反應堆(dui)實驗和(he)核反應堆(dui)。熔鹽(yan)(yan)(yan)具(ju)有熱(re)(re)(re)容量大(da)、蒸汽壓(ya)低、導電性(xing)好、熱(re)(re)(re)穩(wen)定性(xing)和(he)化學(xue)穩(wen)定性(xing)等(deng)(deng)諸多優勢，是公認(ren)的中高溫傳(chuan)熱(re)(re)(re)蓄熱(re)(re)(re)介(jie)質(zhi)。

熔(rong)(rong)(rong)(rong)鹽(yan)(yan)(yan)應用(yong)于(yu)實(shi)際工(gong)程(cheng)需要防止凝固和(he)(he)分解，因此(ci)常(chang)關注熔(rong)(rong)(rong)(rong)點(dian)和(he)(he)沸點(dian)，兩個參數決定了熔(rong)(rong)(rong)(rong)鹽(yan)(yan)(yan)運行溫度(du)，限制了不(bu)同熔(rong)(rong)(rong)(rong)鹽(yan)(yan)(yan)的應用(yong)領域(yu)。熔(rong)(rong)(rong)(rong)鹽(yan)(yan)(yan)按熔(rong)(rong)(rong)(rong)點(dian)從(cong)大(da)到小可分為氟(fu)化(hua)(hua)鹽(yan)(yan)(yan)、碳酸(suan)鹽(yan)(yan)(yan)、氯化(hua)(hua)鹽(yan)(yan)(yan)、硝酸(suan)鹽(yan)(yan)(yan)。其中，高熔(rong)(rong)(rong)(rong)點(dian)氟(fu)化(hua)(hua)鹽(yan)(yan)(yan)作為冷卻(que)劑(ji)，用(yong)于(yu)釷基堆核(he)能(neng)系統研(yan)發(fa)；熔(rong)(rong)(rong)(rong)融碳酸(suan)鹽(yan)(yan)(yan)作為電解質(zhi)，用(yong)于(yu)新(xin)型燃(ran)(ran)料電池研(yan)發(fa)，氯化(hua)(hua)鹽(yan)(yan)(yan)和(he)(he)硝酸(suan)鹽(yan)(yan)(yan)運行溫度(du)符合(he)太陽能(neng)儲(chu)熱電站(zhan)需求，但(dan)氯化(hua)(hua)鹽(yan)(yan)(yan)腐(fu)蝕性強，因此(ci)商(shang)業化(hua)(hua)太陽能(neng)儲(chu)熱電站(zhan)常(chang)采(cai)用(yong)二(er)元鹽(yan)(yan)(yan)(Solar Salt)和(he)(he)三元鹽(yan)(yan)(yan)（Hitec Salt）。耦合(he)燃(ran)(ran)煤發(fa)電的熔(rong)(rong)(rong)(rong)鹽(yan)(yan)(yan)儲(chu)熱，對熔(rong)(rong)(rong)(rong)鹽(yan)(yan)(yan)運行溫度(du)區(qu)間要求與太陽能(neng)儲(chu)熱電站(zhan)相近。因此(ci)，本文研(yan)究過(guo)程(cheng)中考慮(lv)采(cai)用(yong)二(er)元鹽(yan)(yan)(yan)和(he)(he)三元鹽(yan)(yan)(yan)。

本(ben)文針(zhen)對(dui)(dui)耦合350 MW燃煤發電(dian)機(ji)組的(de)熔(rong)鹽(yan)(yan)系(xi)統(tong)(tong)展(zhan)開研究(jiu)，熔(rong)鹽(yan)(yan)系(xi)統(tong)(tong)直接吸收鍋(guo)爐多(duo)余熱量進行(xing)(xing)儲(chu)熱，在機(ji)組高負(fu)荷(he)段(50%-100%THA)，熔(rong)鹽(yan)(yan)加熱給水產生蒸汽匯入汽輪機(ji)，獨(du)立承擔3%Pe/min的(de)升負(fu)荷(he)速(su)率。不同種類熔(rong)鹽(yan)(yan)的(de)運行(xing)(xing)溫度、支撐(cheng)升負(fu)荷(he)次數等決定(ding)了熔(rong)鹽(yan)(yan)蒸汽發生系(xi)統(tong)(tong)的(de)發電(dian)效率、系(xi)統(tong)(tong)復(fu)雜(za)性及投資成本(ben)。本(ben)文從熔(rong)鹽(yan)(yan)系(xi)統(tong)(tong)概(gai)念設(she)(she)計出發，綜合采用熱力學(xue)、流動傳熱學(xue)等分析(xi)理論和(he)方(fang)法(fa)，對(dui)(dui)二元鹽(yan)(yan)和(he)三元鹽(yan)(yan)蒸汽發生系(xi)統(tong)(tong)進行(xing)(xing)技術(shu)性和(he)經濟性對(dui)(dui)比分析(xi)。研究(jiu)結果為未來(lai)耦合燃煤發電(dian)機(ji)組熔(rong)鹽(yan)(yan)系(xi)統(tong)(tong)的(de)設(she)(she)計提供支撐(cheng)。

三、耦合燃煤發電的熔鹽系統

圖3為耦合(he)燃(ran)煤(mei)發(fa)電機組(zu)熔(rong)(rong)(rong)(rong)鹽(yan)(yan)(yan)(yan)(yan)(yan)系(xi)統(tong)的(de)(de)(de)概念(nian)設(she)計圖(紅(hong)線)，包括外(wai)(wai)掛(gua)(gua)式(shi)煙(yan)氣(qi)熔(rong)(rong)(rong)(rong)鹽(yan)(yan)(yan)(yan)(yan)(yan)儲(chu)(chu)(chu)(chu)(chu)(chu)熱(re)(re)(re)(re)系(xi)統(tong)、熔(rong)(rong)(rong)(rong)鹽(yan)(yan)(yan)(yan)(yan)(yan)蒸汽(qi)(qi)發(fa)生系(xi)統(tong)和(he)熔(rong)(rong)(rong)(rong)鹽(yan)(yan)(yan)(yan)(yan)(yan)儲(chu)(chu)(chu)(chu)(chu)(chu)存(cun)(cun)系(xi)統(tong)三部分(fen)。熔(rong)(rong)(rong)(rong)鹽(yan)(yan)(yan)(yan)(yan)(yan)儲(chu)(chu)(chu)(chu)(chu)(chu)存(cun)(cun)系(xi)統(tong)是(shi)實(shi)現儲(chu)(chu)(chu)(chu)(chu)(chu)熱(re)(re)(re)(re)和(he)放(fang)熱(re)(re)(re)(re)功(gong)能的(de)(de)(de)連接(jie)紐帶，根(gen)據工藝要求(qiu)設(she)置了熱(re)(re)(re)(re)鹽(yan)(yan)(yan)(yan)(yan)(yan)罐(guan)和(he)冷鹽(yan)(yan)(yan)(yan)(yan)(yan)罐(guan)，分(fen)別存(cun)(cun)放(fang)高溫熔(rong)(rong)(rong)(rong)鹽(yan)(yan)(yan)(yan)(yan)(yan)和(he)低(di)溫熔(rong)(rong)(rong)(rong)鹽(yan)(yan)(yan)(yan)(yan)(yan)。熔(rong)(rong)(rong)(rong)鹽(yan)(yan)(yan)(yan)(yan)(yan)系(xi)統(tong)通過高低(di)溫鹽(yan)(yan)(yan)(yan)(yan)(yan)罐(guan)將外(wai)(wai)掛(gua)(gua)式(shi)煙(yan)氣(qi)熔(rong)(rong)(rong)(rong)鹽(yan)(yan)(yan)(yan)(yan)(yan)儲(chu)(chu)(chu)(chu)(chu)(chu)熱(re)(re)(re)(re)系(xi)統(tong)與熔(rong)(rong)(rong)(rong)鹽(yan)(yan)(yan)(yan)(yan)(yan)蒸汽(qi)(qi)發(fa)生系(xi)統(tong)耦合(he)，實(shi)現儲(chu)(chu)(chu)(chu)(chu)(chu)熱(re)(re)(re)(re)、放(fang)熱(re)(re)(re)(re)功(gong)能。外(wai)(wai)掛(gua)(gua)式(shi)煙(yan)氣(qi)熔(rong)(rong)(rong)(rong)鹽(yan)(yan)(yan)(yan)(yan)(yan)儲(chu)(chu)(chu)(chu)(chu)(chu)熱(re)(re)(re)(re)系(xi)統(tong)為作者所在團隊原(yuan)創技術，該系(xi)統(tong)設(she)置獨立的(de)(de)(de)引風機從鍋爐(lu)(lu)抽(chou)取(qu)(qu)合(he)適溫度的(de)(de)(de)煙(yan)氣(qi)，送(song)至煙(yan)氣(qi)熔(rong)(rong)(rong)(rong)鹽(yan)(yan)(yan)(yan)(yan)(yan)換熱(re)(re)(re)(re)器(qi)加(jia)熱(re)(re)(re)(re)熔(rong)(rong)(rong)(rong)鹽(yan)(yan)(yan)(yan)(yan)(yan)進(jin)行儲(chu)(chu)(chu)(chu)(chu)(chu)熱(re)(re)(re)(re)，冷卻后的(de)(de)(de)煙(yan)氣(qi)返回SCR入口(kou)(如圖3中(zhong)的(de)(de)(de)虛線回路)。儲(chu)(chu)(chu)(chu)(chu)(chu)熱(re)(re)(re)(re)過程中(zhong)需合(he)理抽(chou)取(qu)(qu)煙(yan)氣(qi)量，以保證鍋爐(lu)(lu)安全運行。當熔(rong)(rong)(rong)(rong)鹽(yan)(yan)(yan)(yan)(yan)(yan)系(xi)統(tong)接(jie)到輔助(zhu)機組(zu)升負荷指令(ling)時，熔(rong)(rong)(rong)(rong)鹽(yan)(yan)(yan)(yan)(yan)(yan)蒸汽(qi)(qi)發(fa)生系(xi)統(tong)開始運行。來自除氧器(qi)的(de)(de)(de)給(gei)水經泵送(song)后依次流(liu)(liu)經熔(rong)(rong)(rong)(rong)鹽(yan)(yan)(yan)(yan)(yan)(yan)汽(qi)(qi)水預熱(re)(re)(re)(re)器(qi)、蒸發(fa)器(qi)和(he)過熱(re)(re)(re)(re)器(qi)，與來自熱(re)(re)(re)(re)鹽(yan)(yan)(yan)(yan)(yan)(yan)罐(guan)的(de)(de)(de)熔(rong)(rong)(rong)(rong)鹽(yan)(yan)(yan)(yan)(yan)(yan)逆流(liu)(liu)換熱(re)(re)(re)(re)，產生的(de)(de)(de)過熱(re)(re)(re)(re)蒸汽(qi)(qi)通過補汽(qi)(qi)閥注入汽(qi)(qi)輪機中(zhong)壓缸(gang)中(zhong)間級，為機組(zu)提供3%Pe/min的(de)(de)(de)升負荷速(su)率(lv)。

熔鹽(yan)(yan)蒸汽(qi)發生系統(tong)(tong)提供3%Pe/min的(de)(de)(de)升負荷(he)(he)速率的(de)(de)(de)過(guo)程具有強瞬(shun)態(tai)特性，為避(bi)免冷(leng)態(tai)啟動放(fang)熱(re)(re)對熔鹽(yan)(yan)系統(tong)(tong)的(de)(de)(de)熱(re)(re)沖(chong)擊，熔鹽(yan)(yan)系統(tong)(tong)設置了動態(tai)保溫運(yun)行(xing)模(mo)式(shi)，即在非補汽(qi)工況下熔鹽(yan)(yan)蒸汽(qi)發生系統(tong)(tong)的(de)(de)(de)鹽(yan)(yan)側和(he)水側均(jun)小流量(liang)(liang)(liang)運(yun)行(xing)，建立(li)和(he)放(fang)熱(re)(re)相(xiang)近的(de)(de)(de)溫度場，使(shi)放(fang)熱(re)(re)過(guo)程即時產(chan)汽(qi)注入(ru)汽(qi)輪機中壓缸做(zuo)功。熔鹽(yan)(yan)蒸汽(qi)發生系統(tong)(tong)放(fang)熱(re)(re)過(guo)程中為維持(chi)系統(tong)(tong)壓力和(he)液位穩定，給水和(he)蒸汽(qi)流量(liang)(liang)(liang)應匹配。由圖2所示(shi)的(de)(de)(de)負荷(he)(he)變化(hua)曲線可知，負荷(he)(he)增(zeng)大(da)，所需(xu)蒸汽(qi)流量(liang)(liang)(liang)增(zeng)加，對應的(de)(de)(de)熱(re)(re)量(liang)(liang)(liang)需(xu)求增(zeng)加，熔鹽(yan)(yan)側的(de)(de)(de)流量(liang)(liang)(liang)也隨之(zhi)增(zeng)大(da)。總之(zhi)，為了支撐3%Pe/min的(de)(de)(de)升負荷(he)(he)速率，熔鹽(yan)(yan)和(he)水側流量(liang)(liang)(liang)在幾(ji)分鐘(zhong)內從動態(tai)保溫的(de)(de)(de)小流量(liang)(liang)(liang)增(zeng)加到額定流量(liang)(liang)(liang)，對應放(fang)熱(re)(re)功率隨時間呈(cheng)三角脈(mo)沖(chong)特征，是(shi)典型的(de)(de)(de)強瞬(shun)態(tai)過(guo)程。

四、熔鹽對蒸汽發生系統影響的研究

4.1研究方法

本(ben)文的研(yan)(yan)究(jiu)(jiu)(jiu)對象是耦合某350MW燃(ran)煤發(fa)電機組(zu)的熔鹽(yan)(yan)蒸(zheng)汽發(fa)生系(xi)統，以75%~100%THA升(sheng)負荷過程設計(ji)工況作為熔鹽(yan)(yan)選(xuan)擇的研(yan)(yan)究(jiu)(jiu)(jiu)基(ji)礎。受(shou)限于(yu)熔鹽(yan)(yan)系(xi)統承擔(dan)3%Pe/min升(sheng)負荷速(su)率需求及二元鹽(yan)(yan)和三元鹽(yan)(yan)物(wu)性(xing)參數，綜合系(xi)統熱力(li)計(ji)算與設備傳熱分(fen)析進(jin)行熔鹽(yan)(yan)比選(xuan)及技術(shu)經濟性(xing)研(yan)(yan)究(jiu)(jiu)(jiu)。

主要(yao)研(yan)究方法如(ru)(ru)下(xia)(如(ru)(ru)圖(tu)4)：

(1)根據3%Pe/min的升負荷(he)速率，結合汽(qi)輪機(ji)的熱(re)(re)力(li)計(ji)算(suan)和(he)熔(rong)鹽(yan)(yan)運行溫度(du)區間獲取所需蒸(zheng)汽(qi)和(he)熔(rong)鹽(yan)(yan)流量(liang)，確定熔(rong)鹽(yan)(yan)蒸(zheng)汽(qi)發(fa)(fa)生系統T-Q圖。根據T-Q圖，在滿(man)足蒸(zheng)汽(qi)發(fa)(fa)生系統換熱(re)(re)器設計(ji)原則的基礎上，通過熱(re)(re)力(li)計(ji)算(suan)得到(dao)熔(rong)鹽(yan)(yan)蒸(zheng)汽(qi)發(fa)(fa)生系統熱(re)(re)平衡圖，明確各級換熱(re)(re)器熱(re)(re)負荷(he)Q以及汽(qi)水側和(he)熔(rong)鹽(yan)(yan)側溫度(du)、壓力(li)、流量(liang)等參數。

(2)根(gen)據(ju)(ju)三元(yuan)鹽(yan)和二元(yuan)鹽(yan)物性參(can)數(shu)(shu)(shu)，結合現有文獻(xian)的實驗數(shu)(shu)(shu)據(ju)(ju)和研究(jiu)成(cheng)果(guo)，選(xuan)擇適合高(gao)溫熔(rong)鹽(yan)的傳(chuan)熱及阻力關聯式，借鑒成(cheng)熟的汽水(shui)傳(chuan)熱和阻力關聯式，確(que)定熔(rong)鹽(yan)側和汽水(shui)側傳(chuan)熱系數(shu)(shu)(shu)、溫度和阻力參(can)數(shu)(shu)(shu)等。根(gen)據(ju)(ju)上述研究(jiu)結果(guo)，使用(yong)工程用(yong)成(cheng)熟的HTRI軟件進行換熱器選(xuan)型和設計，根(gen)據(ju)(ju)電網需求選(xuan)擇合適的升負(fu)荷次數(shu)(shu)(shu)，確(que)定熔(rong)鹽(yan)用(yong)量。

在上述(shu)給定邊界條件下，進行三元鹽和二元鹽蒸(zheng)汽發生系統技術性(xing)和經濟性(xing)分析。

4.2熔鹽蒸汽發生系統的技術指標對比

耦合(he)燃煤發電機組的熔(rong)鹽(yan)(yan)系(xi)統選用成熟的二(er)(er)元(yuan)(yuan)鹽(yan)(yan)和(he)三(san)元(yuan)(yuan)鹽(yan)(yan)作為儲熱介質，表1為二(er)(er)元(yuan)(yuan)鹽(yan)(yan)和(he)三(san)元(yuan)(yuan)鹽(yan)(yan)主要參數對比表，包括鹽(yan)(yan)的成份、熔(rong)點(dian)、分解溫(wen)度、運(yun)行(xing)溫(wen)區、密(mi)度及(ji)價(jia)格。

由表1可(ke)知，三(san)(san)(san)元(yuan)(yuan)鹽(yan)(yan)(yan)熔點和(he)分(fen)(fen)(fen)解溫度(du)(du)分(fen)(fen)(fen)別為(wei)(wei)(wei)143℃和(he)450℃，二(er)元(yuan)(yuan)鹽(yan)(yan)(yan)的(de)(de)(de)(de)熔點和(he)分(fen)(fen)(fen)解溫度(du)(du)分(fen)(fen)(fen)別為(wei)(wei)(wei)220℃和(he)585℃。耦合(he)燃煤發電的(de)(de)(de)(de)熔鹽(yan)(yan)(yan)蒸汽發生系統多為(wei)(wei)(wei)變工況運(yun)(yun)行(xing)，為(wei)(wei)(wei)避免熔鹽(yan)(yan)(yan)凝(ning)固風險，二(er)元(yuan)(yuan)鹽(yan)(yan)(yan)及三(san)(san)(san)元(yuan)(yuan)鹽(yan)(yan)(yan)運(yun)(yun)行(xing)溫度(du)(du)下限(xian)(xian)在熔點基礎上(shang)增加~90℃的(de)(de)(de)(de)裕度(du)(du)。同(tong)時為(wei)(wei)(wei)避免變工況運(yun)(yun)行(xing)熔鹽(yan)(yan)(yan)局部分(fen)(fen)(fen)解風險，二(er)元(yuan)(yuan)鹽(yan)(yan)(yan)運(yun)(yun)行(xing)溫度(du)(du)上(shang)限(xian)(xian)在分(fen)(fen)(fen)解溫度(du)(du)基礎上(shang)下降35℃，三(san)(san)(san)元(yuan)(yuan)鹽(yan)(yan)(yan)運(yun)(yun)行(xing)溫度(du)(du)上(shang)限(xian)(xian)應控制(zhi)在400℃以內(nei)。確定二(er)元(yuan)(yuan)鹽(yan)(yan)(yan)運(yun)(yun)行(xing)溫度(du)(du)(310~550)℃，三(san)(san)(san)元(yuan)(yuan)鹽(yan)(yan)(yan)運(yun)(yun)行(xing)溫度(du)(du)區間(230~390)℃。在給定溫度(du)(du)下(350℃)，二(er)元(yuan)(yuan)鹽(yan)(yan)(yan)和(he)三(san)(san)(san)元(yuan)(yuan)鹽(yan)(yan)(yan)的(de)(de)(de)(de)密度(du)(du)基本(ben)相同(tong)，分(fen)(fen)(fen)別為(wei)(wei)(wei)1867.4 kg/m3和(he)1823.5 kg/m3。二(er)元(yuan)(yuan)鹽(yan)(yan)(yan)和(he)三(san)(san)(san)元(yuan)(yuan)鹽(yan)(yan)(yan)均為(wei)(wei)(wei)成熟的(de)(de)(de)(de)商業(ye)用鹽(yan)(yan)(yan)，三(san)(san)(san)元(yuan)(yuan)鹽(yan)(yan)(yan)的(de)(de)(de)(de)價位略高。

為定(ding)量評估和(he)(he)對比二元鹽和(he)(he)三元鹽蒸汽發(fa)生系(xi)統技術指標，定(ding)義熔鹽系(xi)統發(fa)電效率(hS?E)：

式(1)中，PIP為補(bu)汽后的發(fa)電量(liang)，PB為基準(zhun)負荷(he)發(fa)電量(liang)，Phr為熔鹽蒸汽發(fa)生系(xi)統(tong)放(fang)熱功率:

式(2)中，GSI為補(bu)汽(qi)流量；h1為補(bu)汽(qi)焓(han)值(zhi)；h2為熔鹽蒸汽(qi)發(fa)生系(xi)(xi)統給水焓(han)值(zhi)。設(she)計(ji)(ji)工況下，設(she)計(ji)(ji)工況下二元(yuan)鹽和(he)(he)(he)三元(yuan)鹽蒸汽(qi)發(fa)生系(xi)(xi)統匯入汽(qi)輪機的蒸汽(qi)溫度分(fen)別為~513℃和(he)(he)(he)~375℃。對應(ying)的熔鹽蒸汽(qi)發(fa)生系(xi)(xi)統發(fa)電效率分(fen)別為36.7%和(he)(he)(he)29.2%，如(ru)圖5中虛線圈所示。

在實際工(gong)程中(zhong)，熱(re)鹽(yan)罐中(zhong)熱(re)鹽(yan)溫度直接影響熔(rong)鹽(yan)蒸(zheng)汽發生系統的(de)產汽溫度。影響熱(re)鹽(yan)溫度的(de)因素主要(yao)包括：

(1)儲熱過(guo)程中產生的熱鹽溫度(du)存在偏差(cha)；

(2)放置過程中(zhong)熱鹽(yan)罐散熱引起的溫(wen)降(jiang)；

(3)蒸汽(qi)管道散熱和(he)壓降引(yin)起的溫降等。

上述原(yuan)因均會導致熔(rong)鹽(yan)蒸(zheng)(zheng)(zheng)汽(qi)(qi)發(fa)(fa)生(sheng)系(xi)(xi)統(tong)(tong)產(chan)生(sheng)蒸(zheng)(zheng)(zheng)汽(qi)(qi)溫(wen)度(du)(du)(du)的(de)波動。為(wei)保證(zheng)蒸(zheng)(zheng)(zheng)汽(qi)(qi)溫(wen)度(du)(du)(du)符合汽(qi)(qi)輪起的(de)要求(qiu)，熔(rong)鹽(yan)蒸(zheng)(zheng)(zheng)汽(qi)(qi)發(fa)(fa)生(sheng)系(xi)(xi)統(tong)(tong)產(chan)生(sheng)蒸(zheng)(zheng)(zheng)汽(qi)(qi)溫(wen)度(du)(du)(du)的(de)允許偏(pian)差(cha)為(wei)設計溫(wen)度(du)(du)(du)的(de)±10℃。熔(rong)鹽(yan)蒸(zheng)(zheng)(zheng)汽(qi)(qi)發(fa)(fa)生(sheng)系(xi)(xi)統(tong)(tong)發(fa)(fa)電效率(lv)隨產(chan)汽(qi)(qi)溫(wen)度(du)(du)(du)的(de)變化如圖5所示。由(you)圖可知(zhi)，隨著蒸(zheng)(zheng)(zheng)汽(qi)(qi)溫(wen)度(du)(du)(du)的(de)增加，熔(rong)鹽(yan)蒸(zheng)(zheng)(zheng)汽(qi)(qi)發(fa)(fa)生(sheng)系(xi)(xi)統(tong)(tong)發(fa)(fa)電效率(lv)呈線性(xing)增加趨勢。當三元鹽(yan)蒸(zheng)(zheng)(zheng)汽(qi)(qi)發(fa)(fa)生(sheng)系(xi)(xi)統(tong)(tong)產(chan)汽(qi)(qi)溫(wen)度(du)(du)(du)由(you)365℃升高(gao)到(dao)(dao)(dao)385℃，對(dui)(dui)應熔(rong)鹽(yan)系(xi)(xi)統(tong)(tong)的(de)發(fa)(fa)電效率(lv)從28.9%增加到(dao)(dao)(dao)29.4%，平均發(fa)(fa)電效率(lv)為(wei)29.2%；二元鹽(yan)蒸(zheng)(zheng)(zheng)汽(qi)(qi)發(fa)(fa)生(sheng)系(xi)(xi)統(tong)(tong)產(chan)汽(qi)(qi)溫(wen)度(du)(du)(du)由(you)503℃升高(gao)到(dao)(dao)(dao)523℃時，對(dui)(dui)應熔(rong)鹽(yan)系(xi)(xi)統(tong)(tong)的(de)發(fa)(fa)電效率(lv)從36.5%增加到(dao)(dao)(dao)36.9%，平均發(fa)(fa)電效率(lv)為(wei)36.7%。

綜上所述，三元(yuan)鹽(yan)(yan)蒸(zheng)汽(qi)(qi)發(fa)生(sheng)系統(tong)產(chan)生(sheng)的(de)蒸(zheng)汽(qi)(qi)溫度比二元(yuan)鹽(yan)(yan)低，注入汽(qi)(qi)輪機的(de)位置更靠后，對應較低的(de)發(fa)電(dian)效率。

在(zai)機(ji)(ji)(ji)組(zu)高(gao)負(fu)(fu)荷(he)(he)段(duan)(50%~100%THA)，根據燃(ran)煤(mei)機(ji)(ji)(ji)組(zu)實(shi)際調峰(feng)運行情況(kuang)，將熔(rong)鹽系統(tong)在(zai)單次升負(fu)(fu)荷(he)(he)范圍定位(wei)X→X+25%Pe(X為(wei)50%THA~75%THA)。以75%THA~100%THA升負(fu)(fu)荷(he)(he)范圍為(wei)例，為(wei)實(shi)現燃(ran)煤(mei)機(ji)(ji)(ji)組(zu)6%Pe/min的(de)(de)升負(fu)(fu)荷(he)(he)速(su)(su)率(lv)(圖(tu)6a-b中(zhong)的(de)(de)黑線)，燃(ran)煤(mei)機(ji)(ji)(ji)組(zu)的(de)(de)鍋(guo)爐按照3%Pe/min的(de)(de)速(su)(su)率(lv)線性升負(fu)(fu)荷(he)(he)到機(ji)(ji)(ji)組(zu)目標負(fu)(fu)荷(he)(he)(圖(tu)6a-b中(zhong)的(de)(de)藍線)，熔(rong)鹽蒸汽發生(sheng)(sheng)系統(tong)以3%Pe/min速(su)(su)率(lv)升到峰(feng)值后逐漸降低負(fu)(fu)荷(he)(he)直至退出，熔(rong)鹽蒸汽發生(sheng)(sheng)系統(tong)熱功率(lv)呈現三(san)角形變化趨勢(圖(tu)6a-b中(zhong)的(de)(de)紅線)。二元鹽相比于(yu)三(san)元鹽運行溫(wen)(wen)度高(gao)，能產生(sheng)(sheng)更高(gao)溫(wen)(wen)度的(de)(de)蒸汽，在(zai)汽輪(lun)機(ji)(ji)(ji)中(zhong)壓缸確(que)定溫(wen)(wen)度匹配的(de)(de)匯入點，對應蒸汽壓力也高(gao)。

因此，二(er)元(yuan)(yuan)鹽(yan)(yan)(yan)蒸(zheng)汽(qi)(qi)發生(sheng)(sheng)系(xi)(xi)(xi)(xi)統(tong)(tong)(tong)能產生(sheng)(sheng)更(geng)高品位蒸(zheng)汽(qi)(qi)。考慮熔鹽(yan)(yan)(yan)蒸(zheng)汽(qi)(qi)發生(sheng)(sheng)系(xi)(xi)(xi)(xi)統(tong)(tong)(tong)匯(hui)入汽(qi)(qi)輪機(ji)過程(cheng)中節流損失引起的(de)溫(wen)降，確定(ding)二(er)元(yuan)(yuan)鹽(yan)(yan)(yan)和(he)三元(yuan)(yuan)鹽(yan)(yan)(yan)蒸(zheng)汽(qi)(qi)發生(sheng)(sheng)系(xi)(xi)(xi)(xi)統(tong)(tong)(tong)產生(sheng)(sheng)的(de)蒸(zheng)汽(qi)(qi)分別匯(hui)入中壓(ya)(ya)缸5級(ji)后和(he)中壓(ya)(ya)缸13級(ji)后。二(er)元(yuan)(yuan)鹽(yan)(yan)(yan)比三元(yuan)(yuan)鹽(yan)(yan)(yan)產生(sheng)(sheng)蒸(zheng)汽(qi)(qi)在汽(qi)(qi)輪機(ji)的(de)匯(hui)入點更(geng)靠(kao)前，定(ding)性上進(jin)一步說明二(er)元(yuan)(yuan)鹽(yan)(yan)(yan)蒸(zheng)汽(qi)(qi)發生(sheng)(sheng)系(xi)(xi)(xi)(xi)統(tong)(tong)(tong)能量利用效率優于三元(yuan)(yuan)鹽(yan)(yan)(yan)蒸(zheng)汽(qi)(qi)發生(sheng)(sheng)系(xi)(xi)(xi)(xi)統(tong)(tong)(tong)。根據熔鹽(yan)(yan)(yan)蒸(zheng)汽(qi)(qi)發生(sheng)(sheng)系(xi)(xi)(xi)(xi)統(tong)(tong)(tong)設計工(gong)況發電效率及3%Pe/min升負荷速率要(yao)求，確定(ding)二(er)元(yuan)(yuan)鹽(yan)(yan)(yan)和(he)三元(yuan)(yuan)鹽(yan)(yan)(yan)蒸(zheng)汽(qi)(qi)發生(sheng)(sheng)系(xi)(xi)(xi)(xi)統(tong)(tong)(tong)的(de)峰值熱功率分別為136.5 MW和(he)165.8 MW(詳見圖6a-b)。

針對(dui)熔鹽(yan)(yan)(yan)蒸汽(qi)(qi)(qi)(qi)發(fa)(fa)(fa)生(sheng)(sheng)系(xi)統(tong)，考慮(lv)(lv)系(xi)統(tong)運行(xing)效率(lv)、安全性(xing)和(he)(he)系(xi)統(tong)經(jing)濟(ji)(ji)性(xing)等多方(fang)面(mian)因素，合理確(que)(que)定熱(re)鹽(yan)(yan)(yan)/冷鹽(yan)(yan)(yan)溫(wen)度(du)(du)(du)(du)、匯汽(qi)(qi)(qi)(qi)點(dian)(dian)參數、給水點(dian)(dian)位(wei)置(zhi)及參數和(he)(he)蒸汽(qi)(qi)(qi)(qi)發(fa)(fa)(fa)生(sheng)(sheng)系(xi)統(tong)壓力，如圖(tu)(tu)6c-d所(suo)(suo)示(shi)(shi)(shi)。熱(re)鹽(yan)(yan)(yan)溫(wen)度(du)(du)(du)(du)越(yue)高/冷鹽(yan)(yan)(yan)溫(wen)度(du)(du)(du)(du)越(yue)低(di)，單(dan)位(wei)質量(liang)熔鹽(yan)(yan)(yan)儲熱(re)容量(liang)越(yue)高，熔鹽(yan)(yan)(yan)用(yong)量(liang)越(yue)少，蒸汽(qi)(qi)(qi)(qi)發(fa)(fa)(fa)生(sheng)(sheng)系(xi)統(tong)運行(xing)時(shi)熱(re)鹽(yan)(yan)(yan)泵的(de)(de)功耗減低(di)，從(cong)系(xi)統(tong)效率(lv)及運行(xing)成(cheng)本考慮(lv)(lv)，應盡量(liang)提(ti)高熱(re)鹽(yan)(yan)(yan)溫(wen)度(du)(du)(du)(du)/降低(di)冷鹽(yan)(yan)(yan)溫(wen)度(du)(du)(du)(du)。從(cong)熔鹽(yan)(yan)(yan)安全性(xing)和(he)(he)系(xi)統(tong)經(jing)濟(ji)(ji)性(xing)兩方(fang)面(mian)考慮(lv)(lv)，二元(yuan)鹽(yan)(yan)(yan)和(he)(he)三(san)元(yuan)鹽(yan)(yan)(yan)蒸汽(qi)(qi)(qi)(qi)發(fa)(fa)(fa)生(sheng)(sheng)系(xi)統(tong)的(de)(de)熱(re)鹽(yan)(yan)(yan)溫(wen)度(du)(du)(du)(du)分別設置(zhi)為(wei)550℃(如圖(tu)(tu)6c的(de)(de)A點(dian)(dian)所(suo)(suo)示(shi)(shi)(shi))和(he)(he)390℃(如圖(tu)(tu)6d的(de)(de)A'點(dian)(dian)所(suo)(suo)示(shi)(shi)(shi))。冷鹽(yan)(yan)(yan)溫(wen)度(du)(du)(du)(du)的(de)(de)選(xuan)擇受熔鹽(yan)(yan)(yan)凝固溫(wen)度(du)(du)(du)(du)和(he)(he)蒸發(fa)(fa)(fa)器入口(kou)傳熱(re)窄點(dian)(dian)溫(wen)差限制，冷鹽(yan)(yan)(yan)的(de)(de)溫(wen)度(du)(du)(du)(du)在熔點(dian)(dian)基礎(chu)上增加~90℃的(de)(de)裕(yu)度(du)(du)(du)(du)，確(que)(que)定二元(yuan)鹽(yan)(yan)(yan)和(he)(he)三(san)元(yuan)鹽(yan)(yan)(yan)蒸汽(qi)(qi)(qi)(qi)發(fa)(fa)(fa)生(sheng)(sheng)系(xi)統(tong)的(de)(de)冷鹽(yan)(yan)(yan)溫(wen)度(du)(du)(du)(du)分別為(wei)235℃(如圖(tu)(tu)6c的(de)(de)B點(dian)(dian)所(suo)(suo)示(shi)(shi)(shi))和(he)(he)310℃(如圖(tu)(tu)6d的(de)(de)B'點(dian)(dian)所(suo)(suo)示(shi)(shi)(shi))。

為(wei)(wei)(wei)提高(gao)機(ji)(ji)組(zu)運行(xing)效率，熔(rong)(rong)鹽(yan)(yan)(yan)(yan)(yan)蒸(zheng)(zheng)汽(qi)(qi)(qi)(qi)(qi)(qi)(qi)發(fa)(fa)(fa)生(sheng)(sheng)系(xi)(xi)統(tong)(tong)(tong)(tong)產汽(qi)(qi)(qi)(qi)(qi)(qi)(qi)匯(hui)(hui)(hui)入(ru)(ru)(ru)(ru)點應盡量(liang)在(zai)汽(qi)(qi)(qi)(qi)(qi)(qi)(qi)輪機(ji)(ji)的(de)(de)靠前位置(zhi)。根據流(liu)動傳(chuan)熱(re)(re)(re)學(xue)原(yuan)理，產汽(qi)(qi)(qi)(qi)(qi)(qi)(qi)溫(wen)(wen)(wen)度由熱(re)(re)(re)鹽(yan)(yan)(yan)(yan)(yan)溫(wen)(wen)(wen)度及(ji)過(guo)(guo)熱(re)(re)(re)器(qi)(qi)(qi)出口(kou)端差(cha)(cha)共同(tong)決(jue)定(ding)(ding)(ding)。根據換熱(re)(re)(re)器(qi)(qi)(qi)設(she)計(ji)原(yuan)則(ze)，過(guo)(guo)熱(re)(re)(re)器(qi)(qi)(qi)出口(kou)端差(cha)(cha)應>10℃，同(tong)時為(wei)(wei)(wei)匹配(pei)合適(shi)的(de)(de)匯(hui)(hui)(hui)汽(qi)(qi)(qi)(qi)(qi)(qi)(qi)位置(zhi)，設(she)定(ding)(ding)(ding)二元(yuan)(yuan)鹽(yan)(yan)(yan)(yan)(yan)和(he)(he)(he)三(san)元(yuan)(yuan)鹽(yan)(yan)(yan)(yan)(yan)蒸(zheng)(zheng)汽(qi)(qi)(qi)(qi)(qi)(qi)(qi)發(fa)(fa)(fa)生(sheng)(sheng)系(xi)(xi)統(tong)(tong)(tong)(tong)過(guo)(guo)熱(re)(re)(re)器(qi)(qi)(qi)出口(kou)蒸(zheng)(zheng)汽(qi)(qi)(qi)(qi)(qi)(qi)(qi)溫(wen)(wen)(wen)度分別(bie)為(wei)(wei)(wei)516℃(如(ru)圖(tu)6c的(de)(de)C點所(suo)示)和(he)(he)(he)378℃(如(ru)圖(tu)6d的(de)(de)C'點所(suo)示)。熔(rong)(rong)鹽(yan)(yan)(yan)(yan)(yan)蒸(zheng)(zheng)汽(qi)(qi)(qi)(qi)(qi)(qi)(qi)發(fa)(fa)(fa)生(sheng)(sheng)系(xi)(xi)統(tong)(tong)(tong)(tong)運行(xing)時，給水(shui)從原(yuan)燃煤機(ji)(ji)組(zu)取(qu)(qu)水(shui)，加熱(re)(re)(re)為(wei)(wei)(wei)過(guo)(guo)熱(re)(re)(re)蒸(zheng)(zheng)汽(qi)(qi)(qi)(qi)(qi)(qi)(qi)匯(hui)(hui)(hui)入(ru)(ru)(ru)(ru)汽(qi)(qi)(qi)(qi)(qi)(qi)(qi)輪機(ji)(ji)。為(wei)(wei)(wei)了減少對原(yuan)機(ji)(ji)組(zu)的(de)(de)影(ying)響，取(qu)(qu)水(shui)點應設(she)置(zhi)在(zai)大容器(qi)(qi)(qi)內，例如(ru)凝(ning)結水(shui)井和(he)(he)(he)除氧(yang)器(qi)(qi)(qi)。凝(ning)結水(shui)溫(wen)(wen)(wen)遠(yuan)低(di)于(yu)(yu)熔(rong)(rong)鹽(yan)(yan)(yan)(yan)(yan)熔(rong)(rong)點，需(xu)要對給水(shui)進行(xing)預熱(re)(re)(re)，否則(ze)將導致熔(rong)(rong)鹽(yan)(yan)(yan)(yan)(yan)凝(ning)固，不能(neng)作為(wei)(wei)(wei)熔(rong)(rong)鹽(yan)(yan)(yan)(yan)(yan)蒸(zheng)(zheng)汽(qi)(qi)(qi)(qi)(qi)(qi)(qi)發(fa)(fa)(fa)生(sheng)(sheng)系(xi)(xi)統(tong)(tong)(tong)(tong)給水(shui)。因此，選取(qu)(qu)除氧(yang)器(qi)(qi)(qi)為(wei)(wei)(wei)熔(rong)(rong)鹽(yan)(yan)(yan)(yan)(yan)系(xi)(xi)統(tong)(tong)(tong)(tong)給水(shui)源，設(she)置(zhi)獨立給水(shui)泵取(qu)(qu)水(shui)，設(she)計(ji)工況下給水(shui)溫(wen)(wen)(wen)度為(wei)(wei)(wei)198.5℃，大于(yu)(yu)三(san)元(yuan)(yuan)鹽(yan)(yan)(yan)(yan)(yan)熔(rong)(rong)點溫(wen)(wen)(wen)度，不存在(zai)熔(rong)(rong)鹽(yan)(yan)(yan)(yan)(yan)凝(ning)固風險，但小于(yu)(yu)二元(yuan)(yuan)鹽(yan)(yan)(yan)(yan)(yan)熔(rong)(rong)點溫(wen)(wen)(wen)度，二元(yuan)(yuan)鹽(yan)(yan)(yan)(yan)(yan)需(xu)要抽汽(qi)(qi)(qi)(qi)(qi)(qi)(qi)對給水(shui)進行(xing)預熱(re)(re)(re)，二元(yuan)(yuan)鹽(yan)(yan)(yan)(yan)(yan)和(he)(he)(he)三(san)元(yuan)(yuan)鹽(yan)(yan)(yan)(yan)(yan)蒸(zheng)(zheng)汽(qi)(qi)(qi)(qi)(qi)(qi)(qi)發(fa)(fa)(fa)生(sheng)(sheng)系(xi)(xi)統(tong)(tong)(tong)(tong)蒸(zheng)(zheng)發(fa)(fa)(fa)器(qi)(qi)(qi)入(ru)(ru)(ru)(ru)口(kou)水(shui)溫(wen)(wen)(wen)如(ru)圖(tu)6c的(de)(de)D點和(he)(he)(he)圖(tu)6d的(de)(de)D'點所(suo)示。熔(rong)(rong)鹽(yan)(yan)(yan)(yan)(yan)蒸(zheng)(zheng)汽(qi)(qi)(qi)(qi)(qi)(qi)(qi)發(fa)(fa)(fa)生(sheng)(sheng)系(xi)(xi)統(tong)(tong)(tong)(tong)產生(sheng)(sheng)的(de)(de)蒸(zheng)(zheng)汽(qi)(qi)(qi)(qi)(qi)(qi)(qi)壓(ya)(ya)(ya)力(li)(li)(li)決(jue)定(ding)(ding)(ding)了匯(hui)(hui)(hui)入(ru)(ru)(ru)(ru)汽(qi)(qi)(qi)(qi)(qi)(qi)(qi)輪機(ji)(ji)位置(zhi)和(he)(he)(he)蒸(zheng)(zheng)發(fa)(fa)(fa)器(qi)(qi)(qi)的(de)(de)熱(re)(re)(re)負荷(he)，并(bing)通過(guo)(guo)蒸(zheng)(zheng)發(fa)(fa)(fa)器(qi)(qi)(qi)入(ru)(ru)(ru)(ru)口(kou)傳(chuan)熱(re)(re)(re)窄(zhai)(zhai)點溫(wen)(wen)(wen)差(cha)(cha)限制(zhi)冷鹽(yan)(yan)(yan)(yan)(yan)溫(wen)(wen)(wen)度。為(wei)(wei)(wei)了使(shi)熔(rong)(rong)鹽(yan)(yan)(yan)(yan)(yan)蒸(zheng)(zheng)汽(qi)(qi)(qi)(qi)(qi)(qi)(qi)發(fa)(fa)(fa)生(sheng)(sheng)系(xi)(xi)統(tong)(tong)(tong)(tong)和(he)(he)(he)汽(qi)(qi)(qi)(qi)(qi)(qi)(qi)輪機(ji)(ji)最(zui)大程度上解耦，補汽(qi)(qi)(qi)(qi)(qi)(qi)(qi)閥(fa)后與(yu)閥(fa)前壓(ya)(ya)(ya)力(li)(li)(li)的(de)(de)比值應小于(yu)(yu)0.546，滿足(zu)蒸(zheng)(zheng)汽(qi)(qi)(qi)(qi)(qi)(qi)(qi)臨界流(liu)動特性，使(shi)蒸(zheng)(zheng)汽(qi)(qi)(qi)(qi)(qi)(qi)(qi)流(liu)量(liang)不受閥(fa)后壓(ya)(ya)(ya)力(li)(li)(li)限制(zhi)。二元(yuan)(yuan)鹽(yan)(yan)(yan)(yan)(yan)和(he)(he)(he)三(san)元(yuan)(yuan)鹽(yan)(yan)(yan)(yan)(yan)蒸(zheng)(zheng)汽(qi)(qi)(qi)(qi)(qi)(qi)(qi)發(fa)(fa)(fa)生(sheng)(sheng)系(xi)(xi)統(tong)(tong)(tong)(tong)匯(hui)(hui)(hui)入(ru)(ru)(ru)(ru)汽(qi)(qi)(qi)(qi)(qi)(qi)(qi)輪機(ji)(ji)位置(zhi)對應壓(ya)(ya)(ya)力(li)(li)(li)分別(bie)為(wei)(wei)(wei)3.4 MPa和(he)(he)(he)1.49 MPa，確定(ding)(ding)(ding)閥(fa)前蒸(zheng)(zheng)汽(qi)(qi)(qi)(qi)(qi)(qi)(qi)發(fa)(fa)(fa)生(sheng)(sheng)系(xi)(xi)統(tong)(tong)(tong)(tong)的(de)(de)壓(ya)(ya)(ya)力(li)(li)(li)分別(bie)為(wei)(wei)(wei)6.23 MPa和(he)(he)(he)2.73 MPa。蒸(zheng)(zheng)發(fa)(fa)(fa)器(qi)(qi)(qi)壓(ya)(ya)(ya)力(li)(li)(li)設(she)計(ji)值需(xu)高(gao)于(yu)(yu)匯(hui)(hui)(hui)汽(qi)(qi)(qi)(qi)(qi)(qi)(qi)所(suo)需(xu)的(de)(de)最(zui)低(di)壓(ya)(ya)(ya)力(li)(li)(li)，在(zai)滿足(zu)不小于(yu)(yu)8℃傳(chuan)熱(re)(re)(re)窄(zhai)(zhai)點溫(wen)(wen)(wen)差(cha)(cha)的(de)(de)前提下，壓(ya)(ya)(ya)力(li)(li)(li)應盡可(ke)能(neng)高(gao)，避(bi)免兩相流(liu)不穩定(ding)(ding)(ding)性，同(tong)時需(xu)考慮承壓(ya)(ya)(ya)能(neng)力(li)(li)(li)對設(she)備投資的(de)(de)影(ying)響。最(zui)終確定(ding)(ding)(ding)二元(yuan)(yuan)鹽(yan)(yan)(yan)(yan)(yan)和(he)(he)(he)三(san)元(yuan)(yuan)鹽(yan)(yan)(yan)(yan)(yan)蒸(zheng)(zheng)汽(qi)(qi)(qi)(qi)(qi)(qi)(qi)發(fa)(fa)(fa)生(sheng)(sheng)系(xi)(xi)統(tong)(tong)(tong)(tong)壓(ya)(ya)(ya)力(li)(li)(li)分別(bie)為(wei)(wei)(wei)6.9 MPa和(he)(he)(he)3.29 MPa。

美國圣地安(an)國家(jia)實驗室報(bao)告(gao)中給(gei)出了二(er)(er)元(yuan)(yuan)(yuan)(yuan)鹽(yan)(yan)(yan)(yan)(yan)(yan)密(mi)度(du)、粘(zhan)度(du)、導熱(re)(re)系(xi)數(shu)、比(bi)熱(re)(re)數(shu)據及計算公(gong)式，與(yu)物(wu)性計算方法基本相符(fu)，同時(shi)二(er)(er)元(yuan)(yuan)(yuan)(yuan)鹽(yan)(yan)(yan)(yan)(yan)(yan)的物(wu)性也(ye)通過(guo)實驗數(shu)據得到(dao)了驗證。給(gei)出了三元(yuan)(yuan)(yuan)(yuan)鹽(yan)(yan)(yan)(yan)(yan)(yan)的密(mi)度(du)、粘(zhan)度(du)、導熱(re)(re)系(xi)數(shu)和(he)比(bi)熱(re)(re)容(rong)等參數(shu)的計算公(gong)式。圖(tu)(tu)(tu)7匯總(zong)了二(er)(er)元(yuan)(yuan)(yuan)(yuan)鹽(yan)(yan)(yan)(yan)(yan)(yan)和(he)三元(yuan)(yuan)(yuan)(yuan)鹽(yan)(yan)(yan)(yan)(yan)(yan)物(wu)性(μ、λ、cp和(he)Pr)隨(sui)(sui)溫(wen)(wen)(wen)(wen)度(du)的變(bian)化(hua)(hua)趨(qu)(qu)勢(shi)(shi)。由圖(tu)(tu)(tu)可知，二(er)(er)元(yuan)(yuan)(yuan)(yuan)鹽(yan)(yan)(yan)(yan)(yan)(yan)和(he)三元(yuan)(yuan)(yuan)(yuan)鹽(yan)(yan)(yan)(yan)(yan)(yan)在運(yun)行(xing)溫(wen)(wen)(wen)(wen)度(du)區間內(nei)粘(zhan)度(du)μ隨(sui)(sui)溫(wen)(wen)(wen)(wen)度(du)增(zeng)加(jia)呈快速降(jiang)低，隨(sui)(sui)后逐漸趨(qu)(qu)向平緩的變(bian)化(hua)(hua)趨(qu)(qu)勢(shi)(shi)，交叉溫(wen)(wen)(wen)(wen)度(du)范圍內(nei)兩種熔(rong)鹽(yan)(yan)(yan)(yan)(yan)(yan)的μ重(zhong)疊(die)，如(ru)圖(tu)(tu)(tu)7a。熔(rong)鹽(yan)(yan)(yan)(yan)(yan)(yan)的成(cheng)份影響導熱(re)(re)系(xi)數(shu)λ、比(bi)熱(re)(re)容(rong)cp和(he)普朗特數(shu)Pr隨(sui)(sui)溫(wen)(wen)(wen)(wen)度(du)的變(bian)化(hua)(hua)趨(qu)(qu)勢(shi)(shi)。二(er)(er)元(yuan)(yuan)(yuan)(yuan)鹽(yan)(yan)(yan)(yan)(yan)(yan)λ隨(sui)(sui)溫(wen)(wen)(wen)(wen)度(du)增(zeng)加(jia)而增(zeng)大，三元(yuan)(yuan)(yuan)(yuan)鹽(yan)(yan)(yan)(yan)(yan)(yan)導熱(re)(re)系(xi)數(shu)λ隨(sui)(sui)溫(wen)(wen)(wen)(wen)度(du)增(zeng)加(jia)呈下降(jiang)變(bian)化(hua)(hua)趨(qu)(qu)勢(shi)(shi)，如(ru)圖(tu)(tu)(tu)7b。二(er)(er)元(yuan)(yuan)(yuan)(yuan)鹽(yan)(yan)(yan)(yan)(yan)(yan)cp隨(sui)(sui)溫(wen)(wen)(wen)(wen)度(du)增(zeng)大線(xian)性增(zeng)加(jia)，而三元(yuan)(yuan)(yuan)(yuan)鹽(yan)(yan)(yan)(yan)(yan)(yan)比(bi)熱(re)(re)容(rong)則不(bu)受溫(wen)(wen)(wen)(wen)度(du)影響，在各(ge)溫(wen)(wen)(wen)(wen)度(du)下均為常數(shu)~1.56 kJ/(kg·K)，如(ru)圖(tu)(tu)(tu)7c。二(er)(er)元(yuan)(yuan)(yuan)(yuan)鹽(yan)(yan)(yan)(yan)(yan)(yan)和(he)三元(yuan)(yuan)(yuan)(yuan)鹽(yan)(yan)(yan)(yan)(yan)(yan)的Pr隨(sui)(sui)溫(wen)(wen)(wen)(wen)度(du)的增(zeng)加(jia)呈下降(jiang)趨(qu)(qu)勢(shi)(shi)，兩種鹽(yan)(yan)(yan)(yan)(yan)(yan)的變(bian)化(hua)(hua)趨(qu)(qu)勢(shi)(shi)一致，且二(er)(er)元(yuan)(yuan)(yuan)(yuan)鹽(yan)(yan)(yan)(yan)(yan)(yan)的Pr值僅為三元(yuan)(yuan)(yuan)(yuan)鹽(yan)(yan)(yan)(yan)(yan)(yan)的2/3,如(ru)圖(tu)(tu)(tu)7d。

在熔鹽(yan)蒸(zheng)汽發(fa)生系(xi)統換熱(re)(re)(re)器(qi)(qi)熱(re)(re)(re)力計算過程(cheng)中，汽水側傳(chuan)熱(re)(re)(re)系(xi)數研究(jiu)較為(wei)成熟(shu)，因此(ci)選擇準確的(de)熔鹽(yan)傳(chuan)熱(re)(re)(re)系(xi)數計算公式極為(wei)重(zhong)要。由4.3節(jie)的(de)描述可以得到，二元(yuan)(yuan)鹽(yan)蒸(zheng)汽發(fa)生器(qi)(qi)系(xi)統中預熱(re)(re)(re)器(qi)(qi)、蒸(zheng)發(fa)器(qi)(qi)和過熱(re)(re)(re)器(qi)(qi)的(de)選型分別(bie)為(wei)BEU、BEU和HAP，三(san)元(yuan)(yuan)鹽(yan)蒸(zheng)汽發(fa)生器(qi)(qi)系(xi)統中預熱(re)(re)(re)器(qi)(qi)、蒸(zheng)發(fa)器(qi)(qi)和過熱(re)(re)(re)器(qi)(qi)的(de)選型分別(bie)為(wei)BGU、BEU和HAP。

上述所有熔(rong)鹽(yan)汽(qi)水換熱(re)(re)器均為(wei)管殼(ke)(ke)式換熱(re)(re)器，根據(ju)(ju)兩側工質(zhi)壓力(li)(li)的(de)(de)不(bu)同(tong)，對管側和殼(ke)(ke)側介質(zhi)進行(xing)分配。其中熔(rong)鹽(yan)側壓力(li)(li)低(di)，走殼(ke)(ke)側；汽(qi)水側壓力(li)(li)高，走管側。同(tong)時(shi)為(wei)了增強(qiang)傳(chuan)熱(re)(re)系統(tong)，在(zai)(zai)殼(ke)(ke)側加裝折(zhe)(zhe)流(liu)板擾流(liu)結(jie)構。現有研(yan)究能描述熔(rong)鹽(yan)在(zai)(zai)殼(ke)(ke)側流(liu)動時(shi)的(de)(de)傳(chuan)熱(re)(re)特性關聯(lian)式少，很多文獻是根據(ju)(ju)自(zi)己的(de)(de)實(shi)驗(yan)數(shu)據(ju)(ju)進行(xing)關聯(lian)式擬合(he)。關于二(er)元(yuan)鹽(yan)和三(san)元(yuan)鹽(yan)在(zai)(zai)帶擾流(liu)結(jie)構的(de)(de)殼(ke)(ke)側流(liu)動時(shi)的(de)(de)實(shi)驗(yan)數(shu)據(ju)(ju)較少，圖(tu)8中給出的(de)(de)Kern關聯(lian)式(3)為(wei)描述流(liu)體(ti)在(zai)(zai)帶弓形折(zhe)(zhe)流(liu)板的(de)(de)殼(ke)(ke)側流(liu)動時(shi)的(de)(de)傳(chuan)統(tong)傳(chuan)熱(re)(re)關聯(lian)式。

由于本(ben)文研(yan)究的(de)(de)熔鹽(yan)汽水(shui)換熱(re)(re)(re)器均為帶折流(liu)板的(de)(de)管(guan)殼式換熱(re)(re)(re)器，可以(yi)采用Kern關聯式進行熔鹽(yan)傳熱(re)(re)(re)分析，具(ju)體(ti)的(de)(de)Nu計算公式如下(xia)：

式(3)中(zhong)(zhong)，Re為雷諾數(shu)，Pr為普朗特(te)數(shu)，m f為流(liu)體平均溫度計(ji)算(suan)流(liu)體的(de)(de)(de)粘度，mw為壁(bi)面(mian)溫度計(ji)算(suan)流(liu)體的(de)(de)(de)粘度。由于(yu)熔(rong)(rong)鹽流(liu)動(dong)(dong)阻(zu)力(li)測(ce)量(liang)難度大(da)，引壓管(guan)內低溫熔(rong)(rong)鹽易凝固(gu)，難以獲得(de)準確(que)的(de)(de)(de)實驗測(ce)量(liang)數(shu)據(ju)。因(yin)此尚未在公開(kai)發表文獻中(zhong)(zhong)檢索到關于(yu)熔(rong)(rong)鹽流(liu)動(dong)(dong)阻(zu)力(li)的(de)(de)(de)測(ce)量(liang)數(shu)據(ju)。通常認為熔(rong)(rong)鹽的(de)(de)(de)流(liu)動(dong)(dong)特(te)性(xing)較好(hao)，與純水(shui)(shui)相(xiang)比只是粘度有所增大(da)。因(yin)此，可以選擇單相(xiang)水(shui)(shui)的(de)(de)(de)阻(zu)力(li)系數(shu)公式近似計(ji)算(suan)熔(rong)(rong)鹽的(de)(de)(de)摩(mo)擦(ca)阻(zu)力(li)系數(shu)。當(dang)雷諾數(shu)低于(yu)2300時，阻(zu)力(li)系數(shu)的(de)(de)(de)計(ji)算(suan)公式：

4.3熔鹽蒸汽發生系統流程及換熱器選型對比

熔(rong)(rong)鹽蒸(zheng)汽(qi)(qi)(qi)發生(sheng)系統(tong)(tong)包括熔(rong)(rong)鹽和汽(qi)(qi)(qi)水(shui)(shui)(shui)(shui)兩個工質(zhi)回路(lu)。對(dui)于熔(rong)(rong)鹽側，熱(re)鹽罐中高溫(wen)熔(rong)(rong)鹽在熱(re)鹽泵驅動下，依(yi)次流(liu)經熔(rong)(rong)鹽汽(qi)(qi)(qi)水(shui)(shui)(shui)(shui)過熱(re)器(qi)(qi)、蒸(zheng)發器(qi)(qi)和預(yu)熱(re)器(qi)(qi)釋放熱(re)量，冷卻后的(de)熔(rong)(rong)鹽送至冷鹽罐。對(dui)于汽(qi)(qi)(qi)水(shui)(shui)(shui)(shui)側，熔(rong)(rong)鹽系統(tong)(tong)給(gei)水(shui)(shui)(shui)(shui)泵從除氧(yang)器(qi)(qi)取水(shui)(shui)(shui)(shui)，依(yi)次流(liu)經各級(ji)換熱(re)器(qi)(qi)，與(yu)熔(rong)(rong)鹽逆流(liu)換熱(re)加熱(re)成為過熱(re)蒸(zheng)汽(qi)(qi)(qi)，匯(hui)入到汽(qi)(qi)(qi)輪(lun)機(ji)中壓缸(gang)中間級(ji)做功。熔(rong)(rong)鹽蒸(zheng)汽(qi)(qi)(qi)發生(sheng)系統(tong)(tong)的(de)給(gei)水(shui)(shui)(shui)(shui)來自(zi)除氧(yang)器(qi)(qi)，設(she)計(ji)工況(kuang)下的(de)給(gei)水(shui)(shui)(shui)(shui)溫(wen)度(du)198.5℃，低(di)于二元鹽的(de)熔(rong)(rong)點。因(yin)此，二元鹽蒸(zheng)汽(qi)(qi)(qi)發生(sheng)系統(tong)(tong)需增設(she)給(gei)水(shui)(shui)(shui)(shui)預(yu)熱(re)器(qi)(qi)，利用抽汽(qi)(qi)(qi)預(yu)熱(re)來自(zi)除氧(yang)器(qi)(qi)的(de)給(gei)水(shui)(shui)(shui)(shui)，加熱(re)給(gei)水(shui)(shui)(shui)(shui)溫(wen)度(du)到260℃，再依(yi)次進入各級(ji)熔(rong)(rong)鹽汽(qi)(qi)(qi)水(shui)(shui)(shui)(shui)換熱(re)器(qi)(qi)(如圖9所示)。

熔(rong)(rong)鹽(yan)(yan)(yan)汽水預熱器(qi)采(cai)用(yong)管殼式(shi)換(huan)熱器(qi)，由于水側(ce)壓力(li)高，走(zou)(zou)管側(ce)，鹽(yan)(yan)(yan)側(ce)壓力(li)低，走(zou)(zou)殼側(ce)。考慮換(huan)熱器(qi)需(xu)要(yao)適應快速變(bian)負荷工況，壓力(li)、溫度及(ji)流量變(bian)化較(jiao)大，采(cai)用(yong)U形管結(jie)構，可有效吸收因熱膨脹產生的軸(zhou)向位移，適應快速變(bian)負荷工況。換(huan)熱管采(cai)用(yong)45°布管方式(shi)，有效減緩振(zhen)動。鑒于三(san)(san)元(yuan)(yuan)鹽(yan)(yan)(yan)蒸汽發生器(qi)系(xi)統(tong)(tong)的熔(rong)(rong)鹽(yan)(yan)(yan)側(ce)流量較(jiao)大，約是二(er)(er)元(yuan)(yuan)鹽(yan)(yan)(yan)系(xi)統(tong)(tong)的2倍。因此，三(san)(san)元(yuan)(yuan)鹽(yan)(yan)(yan)蒸汽發生系(xi)統(tong)(tong)采(cai)用(yong)G型(xing)分(fen)流殼體(ti)型(xing)式(shi)，有效降低殼側(ce)壓損(sun)，而二(er)(er)元(yuan)(yuan)鹽(yan)(yan)(yan)選擇(ze)E型(xing)殼體(ti)型(xing)式(shi)，二(er)(er)元(yuan)(yuan)鹽(yan)(yan)(yan)和三(san)(san)元(yuan)(yuan)鹽(yan)(yan)(yan)汽水預熱器(qi)選型(xing)分(fen)別為BEU和BGU，如圖(tu)9-10所示。

熔(rong)鹽(yan)(yan)汽(qi)(qi)(qi)(qi)水(shui)(shui)(shui)蒸(zheng)(zheng)(zheng)(zheng)發(fa)(fa)器(qi)(qi)的汽(qi)(qi)(qi)(qi)水(shui)(shui)(shui)側(ce)(ce)將飽和水(shui)(shui)(shui)加熱(re)成(cheng)飽和蒸(zheng)(zheng)(zheng)(zheng)汽(qi)(qi)(qi)(qi)，其(qi)中給水(shui)(shui)(shui)來自(zi)熔(rong)鹽(yan)(yan)汽(qi)(qi)(qi)(qi)水(shui)(shui)(shui)預熱(re)器(qi)(qi)，熔(rong)鹽(yan)(yan)來自(zi)熔(rong)鹽(yan)(yan)汽(qi)(qi)(qi)(qi)水(shui)(shui)(shui)過熱(re)器(qi)(qi)。熔(rong)鹽(yan)(yan)汽(qi)(qi)(qi)(qi)水(shui)(shui)(shui)蒸(zheng)(zheng)(zheng)(zheng)發(fa)(fa)器(qi)(qi)在(zai)整個(ge)熔(rong)鹽(yan)(yan)蒸(zheng)(zheng)(zheng)(zheng)汽(qi)(qi)(qi)(qi)發(fa)(fa)生(sheng)系統中，熱(re)負(fu)荷占比最高，換熱(re)面積(ji)大(da)，設(she)備體(ti)積(ji)龐(pang)大(da)，且汽(qi)(qi)(qi)(qi)水(shui)(shui)(shui)側(ce)(ce)發(fa)(fa)生(sheng)相(xiang)變，內(nei)部存(cun)(cun)在(zai)汽(qi)(qi)(qi)(qi)水(shui)(shui)(shui)混(hun)合物(wu)兩(liang)相(xiang)流體(ti)，流動與傳熱(re)機理較(jiao)(jiao)為(wei)復雜，設(she)計難(nan)度(du)(du)最大(da)。根據(ju)汽(qi)(qi)(qi)(qi)水(shui)(shui)(shui)所(suo)(suo)在(zai)的位置不(bu)同(tong)(tong)、原理不(bu)同(tong)(tong)，熔(rong)鹽(yan)(yan)汽(qi)(qi)(qi)(qi)水(shui)(shui)(shui)蒸(zheng)(zheng)(zheng)(zheng)發(fa)(fa)器(qi)(qi)常(chang)(chang)見(jian)的為(wei)換熱(re)管(guan)(guan)管(guan)(guan)外沸(fei)騰(teng)與管(guan)(guan)內(nei)沸(fei)騰(teng)兩(liang)種。其(qi)中管(guan)(guan)外沸(fei)騰(teng)以釜式(shi)(shi)蒸(zheng)(zheng)(zheng)(zheng)發(fa)(fa)器(qi)(qi)最為(wei)常(chang)(chang)見(jian)，在(zai)化(hua)工(gong)和光(guang)熱(re)領域得到了廣泛應(ying)用。但(dan)受(shou)加工(gong)制造技術(shu)的限(xian)制，釜式(shi)(shi)蒸(zheng)(zheng)(zheng)(zheng)發(fa)(fa)器(qi)(qi)的熱(re)功(gong)率受(shou)限(xian)。此(ci)外，由于熔(rong)鹽(yan)(yan)進口溫(wen)(wen)度(du)(du)與出(chu)(chu)口溫(wen)(wen)度(du)(du)溫(wen)(wen)差(cha)(cha)較(jiao)(jiao)大(da)，在(zai)管(guan)(guan)板(ban)的上下及兩(liang)側(ce)(ce)均存(cun)(cun)在(zai)較(jiao)(jiao)大(da)熱(re)應(ying)力(li)。管(guan)(guan)內(nei)蒸(zheng)(zheng)(zheng)(zheng)發(fa)(fa)的汽(qi)(qi)(qi)(qi)包(bao)(bao)式(shi)(shi)蒸(zheng)(zheng)(zheng)(zheng)發(fa)(fa)器(qi)(qi)相(xiang)較(jiao)(jiao)于釜式(shi)(shi)蒸(zheng)(zheng)(zheng)(zheng)發(fa)(fa)器(qi)(qi)，具有更高熱(re)負(fu)荷。且蒸(zheng)(zheng)(zheng)(zheng)發(fa)(fa)器(qi)(qi)管(guan)(guan)側(ce)(ce)入口過冷水(shui)(shui)(shui)溫(wen)(wen)度(du)(du)接近(jin)飽和溫(wen)(wen)度(du)(du)，出(chu)(chu)口為(wei)汽(qi)(qi)(qi)(qi)水(shui)(shui)(shui)混(hun)合物(wu)，溫(wen)(wen)度(du)(du)為(wei)飽和溫(wen)(wen)度(du)(du)，溫(wen)(wen)差(cha)(cha)極小，能夠有效改善管(guan)(guan)側(ce)(ce)進出(chu)(chu)口溫(wen)(wen)差(cha)(cha)熱(re)應(ying)力(li)。綜上所(suo)(suo)述(shu)，熔(rong)鹽(yan)(yan)汽(qi)(qi)(qi)(qi)水(shui)(shui)(shui)蒸(zheng)(zheng)(zheng)(zheng)發(fa)(fa)器(qi)(qi)的選(xuan)型為(wei)BEU式(shi)(shi)汽(qi)(qi)(qi)(qi)包(bao)(bao)式(shi)(shi)蒸(zheng)(zheng)(zheng)(zheng)發(fa)(fa)器(qi)(qi)(如(ru)圖9-10)。

熔鹽汽水過熱(re)(re)器(qi)(qi)對(dui)應汽水側將飽(bao)和蒸(zheng)(zheng)汽加熱(re)(re)至(zhi)過熱(re)(re)蒸(zheng)(zheng)汽，其(qi)中飽(bao)和蒸(zheng)(zheng)汽來自熔鹽汽水蒸(zheng)(zheng)發(fa)器(qi)(qi)，熔鹽來自熱(re)(re)鹽罐。熔鹽汽水過熱(re)(re)器(qi)(qi)采用管殼式(shi)換(huan)熱(re)(re)器(qi)(qi)，蒸(zheng)(zheng)汽壓力高走管側，熔鹽壓力低走殼側。由于(yu)進口與出(chu)口溫差(cha)較大，且(qie)溫度較高，換(huan)熱(re)(re)器(qi)(qi)又經常(chang)運行在快(kuai)速(su)變負荷工(gong)況，壓力、溫度及流量變化較大，因(yin)此換(huan)熱(re)(re)器(qi)(qi)型(xing)式(shi)采用發(fa)夾式(shi)(HAP)，如圖9-10所示。采用該(gai)類型(xing)換(huan)熱(re)(re)器(qi)(qi)一方面避免(mian)了管板(ban)受(shou)到大溫差(cha)應力的(de)作用，另(ling)一方面換(huan)熱(re)(re)管與殼體可(ke)有(you)效吸收因(yin)熱(re)(re)膨脹產生(sheng)的(de)軸向位移，避免(mian)因(yin)熱(re)(re)應力而發(fa)生(sheng)破壞，影響換(huan)熱(re)(re)器(qi)(qi)安(an)全運行。

根(gen)據前(qian)文確定的邊界(jie)條件，采用(yong)HTRI軟件進行換(huan)熱(re)(re)(re)器(qi)(qi)(qi)(qi)熱(re)(re)(re)力(li)計算及設計。在設計工況下(xia)，二元(yuan)鹽蒸(zheng)(zheng)汽發(fa)生系統需要增設熔鹽給(gei)水(shui)預熱(re)(re)(re)器(qi)(qi)(qi)(qi)(如(ru)(ru)圖10)，即從原機組抽取合適參數的蒸(zheng)(zheng)汽送入給(gei)水(shui)預熱(re)(re)(re)器(qi)(qi)(qi)(qi)加熱(re)(re)(re)器(qi)(qi)(qi)(qi)來(lai)自除氧(yang)器(qi)(qi)(qi)(qi)的給(gei)水(shui)。給(gei)水(shui)預熱(re)(re)(re)器(qi)(qi)(qi)(qi)的蒸(zheng)(zheng)汽側入口(kou)溫度為(wei)393.8℃，壓力(li)為(wei)6.94 MPa，出(chu)(chu)口(kou)溫度為(wei)284.2℃，壓力(li)為(wei)6.83 MPa；水(shui)側入口(kou)水(shui)溫為(wei)198.5℃，出(chu)(chu)口(kou)水(shui)溫為(wei)260℃，熱(re)(re)(re)負荷16.9 MW。給(gei)水(shui)預熱(re)(re)(re)器(qi)(qi)(qi)(qi)分為(wei)兩級，均為(wei)管殼(ke)式換(huan)熱(re)(re)(re)器(qi)(qi)(qi)(qi)(BFU和BEU型)，采用(yong)U形管結構，可(ke)有效吸收因熱(re)(re)(re)膨(peng)脹產生的軸向位移，避(bi)免熱(re)(re)(re)應力(li)引起的破壞，影響換(huan)熱(re)(re)(re)器(qi)(qi)(qi)(qi)安(an)全運行。此(ci)外，設計工況下(xia)，熔鹽蒸(zheng)(zheng)汽發(fa)生系統三級換(huan)熱(re)(re)(re)器(qi)(qi)(qi)(qi)的參數如(ru)(ru)表2所示。

綜上所述，二元鹽(yan)與三元鹽(yan)蒸汽發生系統的主要(yao)區別(bie)包括：

1)設計工(gong)況下，除氧(yang)器給水溫度為198.5℃，低(di)于二元鹽熔(rong)點(dian)，高于三元鹽熔(rong)鹽熔(rong)點(dian)，三元鹽蒸汽發生系統無需設置給水預熱器，系統流程更簡潔。

2)二元鹽(yan)(yan)(yan)比三元鹽(yan)(yan)(yan)使用溫度(du)高(gao)，產(chan)(chan)生(sheng)(sheng)的(de)蒸(zheng)(zheng)(zheng)汽(qi)(qi)(qi)品位(wei)更高(gao)。因(yin)此，二元鹽(yan)(yan)(yan)蒸(zheng)(zheng)(zheng)汽(qi)(qi)(qi)發生(sheng)(sheng)系(xi)統產(chan)(chan)生(sheng)(sheng)的(de)蒸(zheng)(zheng)(zheng)汽(qi)(qi)(qi)匯入汽(qi)(qi)(qi)輪機的(de)位(wei)置更靠前，具有更高(gao)的(de)發電效率，對應蒸(zheng)(zheng)(zheng)汽(qi)(qi)(qi)發生(sheng)(sheng)系(xi)統熱(re)(re)功率小(xiao)，換熱(re)(re)器的(de)尺(chi)寸和單次升負荷過程(cheng)的(de)用鹽(yan)(yan)(yan)量均比三元鹽(yan)(yan)(yan)蒸(zheng)(zheng)(zheng)汽(qi)(qi)(qi)發生(sheng)(sheng)系(xi)統少。

4.4熔鹽蒸汽發生系統投資對比

本(ben)文(wen)研(yan)究的(de)耦合(he)燃煤(mei)發(fa)電機(ji)組(zu)的(de)熔(rong)(rong)鹽(yan)(yan)蒸汽(qi)發(fa)生系(xi)(xi)統(tong)(tong)為燃煤(mei)機(ji)組(zu)提供(gong)3%Pe/min的(de)升(sheng)負荷(he)(he)速(su)率(lv)(lv)，使燃煤(mei)機(ji)組(zu)的(de)升(sheng)負荷(he)(he)速(su)率(lv)(lv)達到6%Pe/min，瞄(miao)準(zhun)(zhun)的(de)是未來電網的(de)需(xu)求，遠高于(yu)現(xian)有機(ji)組(zu)的(de)升(sheng)負荷(he)(he)速(su)率(lv)(lv)，無法(fa)根(gen)據現(xian)行(xing)的(de)標準(zhun)(zhun)進(jin)(jin)行(xing)收益計算。另外，耦合(he)燃煤(mei)發(fa)電的(de)熔(rong)(rong)鹽(yan)(yan)系(xi)(xi)統(tong)(tong)目前處于(yu)研(yan)發(fa)和(he)初步建設(she)階段，在役(yi)期間將間斷(duan)運行(xing)，缺乏(fa)年利用(yong)小時(shi)數、廠(chang)用(yong)電率(lv)(lv)、運行(xing)維護(hu)成本(ben)、繳納稅額等全壽命周期數據，難(nan)以(yi)進(jin)(jin)行(xing)常規(gui)平準(zhun)(zhun)化(hua)發(fa)電成本(ben)(LCOE)計算。因(yin)此本(ben)文(wen)借鑒(jian)國內外權威機(ji)構關于(yu)光熱(re)電站熔(rong)(rong)鹽(yan)(yan)蒸汽(qi)發(fa)生系(xi)(xi)統(tong)(tong)設(she)備投資(zi)(zi)計算公式(shi)及廠(chang)家調研(yan)，僅以(yi)熔(rong)(rong)鹽(yan)(yan)蒸汽(qi)發(fa)生系(xi)(xi)統(tong)(tong)的(de)投資(zi)(zi)成本(ben)作為比較二元(yuan)鹽(yan)(yan)和(he)三(san)元(yuan)鹽(yan)(yan)熔(rong)(rong)鹽(yan)(yan)蒸汽(qi)發(fa)生系(xi)(xi)統(tong)(tong)經濟性的(de)評(ping)判標準(zhun)(zhun)。

熔鹽(yan)(yan)蒸汽(qi)發生系統(tong)設備是主要投資(zi)組(zu)成，主要包括(kuo)各級換熱器、熔鹽(yan)(yan)儲罐、動(dong)力(li)設備和管(guan)道等。此外，熔鹽(yan)(yan)用量在(zai)熔鹽(yan)(yan)蒸汽(qi)發生系統(tong)投資(zi)成本中占比(bi)較大(da)，需要在(zai)系統(tong)的(de)經(jing)濟性分析(xi)中考慮。

具體的(de)說，熔鹽(yan)汽水(shui)換熱(re)器(qi)(qi)的(de)投資(zi)成本(ben)是(shi)傳熱(re)面(mian)積、結構型式、所選材料和壓力的(de)函數。根(gen)據文獻(xian)[46,47]，當(dang)換熱(re)器(qi)(qi)面(mian)積2時，換熱(re)器(qi)(qi)的(de)投資(zi)成本(ben)計算如下：

根據熔鹽(yan)汽(qi)水換(huan)熱器的面(mian)積、運行壓力等(deng)參數，結合式(6)-(9)，最終(zhong)確(que)定二元(yuan)鹽(yan)蒸汽(qi)發生(sheng)系(xi)(xi)統投(tou)資(zi)成本(ben)為499.5萬元(yuan)，三(san)元(yuan)鹽(yan)蒸汽(qi)發生(sheng)系(xi)(xi)統投(tou)資(zi)成本(ben)為682.5萬元(yuan)，比二元(yuan)鹽(yan)系(xi)(xi)統高183.0萬元(yuan)。

熔鹽(yan)(yan)罐(guan)(guan)(guan)為(wei)(wei)(wei)(wei)圓柱形(xing)立罐(guan)(guan)(guan)式結構，尺寸由溫(wen)(wen)度(du)差和(he)儲熱介質的(de)(de)(de)等壓熱容決(jue)定。根(gen)據熔鹽(yan)(yan)運(yun)行溫(wen)(wen)度(du)區間，二元(yuan)鹽(yan)(yan)蒸(zheng)汽(qi)發(fa)生(sheng)系統(tong)熱鹽(yan)(yan)罐(guan)(guan)(guan)工作溫(wen)(wen)度(du)為(wei)(wei)(wei)(wei)550℃，選(xuan)材(cai)為(wei)(wei)(wei)(wei)TP347H，冷(leng)鹽(yan)(yan)罐(guan)(guan)(guan)的(de)(de)(de)工作溫(wen)(wen)度(du)為(wei)(wei)(wei)(wei)310℃，選(xuan)材(cai)為(wei)(wei)(wei)(wei)Q345，三(san)元(yuan)鹽(yan)(yan)蒸(zheng)汽(qi)發(fa)生(sheng)系統(tong)冷(leng)熱鹽(yan)(yan)罐(guan)(guan)(guan)的(de)(de)(de)工作溫(wen)(wen)度(du)分(fen)(fen)(fen)別為(wei)(wei)(wei)(wei)235℃和(he)390℃，選(xuan)材(cai)均為(wei)(wei)(wei)(wei)Q345。根(gen)據設(she)計工況(kuang)下熔鹽(yan)(yan)蒸(zheng)汽(qi)發(fa)生(sheng)系統(tong)熱力計算結果，得(de)到二元(yuan)鹽(yan)(yan)和(he)三(san)元(yuan)蒸(zheng)汽(qi)發(fa)生(sheng)系統(tong)峰值升負荷(he)(he)(he)功率分(fen)(fen)(fen)別為(wei)(wei)(wei)(wei)136.5 MW和(he)165.8 MW(如圖9-10)，熔鹽(yan)(yan)系統(tong)支(zhi)撐升負荷(he)(he)(he)時(shi)長(chang)為(wei)(wei)(wei)(wei)500 s，由此確定二元(yuan)鹽(yan)(yan)和(he)三(san)元(yuan)鹽(yan)(yan)蒸(zheng)汽(qi)發(fa)生(sheng)系統(tong)單次(ci)升負荷(he)(he)(he)過程(cheng)所需熱量分(fen)(fen)(fen)別為(wei)(wei)(wei)(wei)9.5 MWhth和(he)11.5 MWhth。以滿足10次(ci)3%Pe/min的(de)(de)(de)升負荷(he)(he)(he)需求(qiu)為(wei)(wei)(wei)(wei)目標(biao)，考慮熔鹽(yan)(yan)罐(guan)(guan)(guan)底部(bu)、設(she)備(bei)和(he)管道(dao)中不(bu)能有效利用的(de)(de)(de)熔鹽(yan)(yan)量，最(zui)終確定二元(yuan)鹽(yan)(yan)和(he)三(san)元(yuan)鹽(yan)(yan)的(de)(de)(de)用量分(fen)(fen)(fen)別為(wei)(wei)(wei)(wei)1700 t和(he)2500 t，儲熱量分(fen)(fen)(fen)別為(wei)(wei)(wei)(wei)95.0 MWhth和(he)115.0 MWhth。

熔(rong)鹽(yan)儲(chu)罐(guan)及相關(guan)配件計算(suan)公式如(ru)下：

式(10)中，WT為(wei)(wei)(wei)(wei)熔(rong)鹽罐(guan)的(de)儲熱(re)量，D1為(wei)(wei)(wei)(wei)熱(re)鹽罐(guan)的(de)材(cai)料(liao)成(cheng)本與(yu)安(an)(an)裝(zhuang)(zhuang)、建設成(cheng)本之(zhi)和(he)，為(wei)(wei)(wei)(wei)46元(yuan)(yuan)/kWhth，D2為(wei)(wei)(wei)(wei)冷鹽罐(guan)的(de)材(cai)料(liao)成(cheng)本與(yu)安(an)(an)裝(zhuang)(zhuang)、建設成(cheng)本之(zhi)和(he)，為(wei)(wei)(wei)(wei)21元(yuan)(yuan)/kWhth，D3為(wei)(wei)(wei)(wei)罐(guan)體保(bao)溫材(cai)料(liao)成(cheng)本與(yu)安(an)(an)裝(zhuang)(zhuang)、建設成(cheng)本之(zhi)和(he)，為(wei)(wei)(wei)(wei)5元(yuan)(yuan)/kWhth，D4為(wei)(wei)(wei)(wei)地基(ji)、支撐(cheng)結構(gou)的(de)材(cai)料(liao)成(cheng)本與(yu)安(an)(an)裝(zhuang)(zhuang)、建設成(cheng)本之(zhi)和(he)，為(wei)(wei)(wei)(wei)17元(yuan)(yuan)/kWhth，D5為(wei)(wei)(wei)(wei)電氣儀(yi)表的(de)材(cai)料(liao)成(cheng)本與(yu)安(an)(an)裝(zhuang)(zhuang)、建設成(cheng)本之(zhi)和(he)，為(wei)(wei)(wei)(wei)6元(yuan)(yuan)/kWhth，D6為(wei)(wei)(wei)(wei)管道(dao)、閥門及其它配件(jian)的(de)材(cai)料(liao)成(cheng)本與(yu)安(an)(an)裝(zhuang)(zhuang)、建設成(cheng)本之(zhi)和(he)，為(wei)(wei)(wei)(wei)2元(yuan)(yuan)/kWhth。

本(ben)(ben)文按照(zhao)式(shi)(10)對熔(rong)(rong)鹽(yan)罐及其附屬設(she)備的投(tou)(tou)資成(cheng)本(ben)(ben)進行計(ji)算(suan)，得(de)到(dao)二元鹽(yan)蒸汽發生系統(tong)熔(rong)(rong)鹽(yan)儲罐的投(tou)(tou)資成(cheng)本(ben)(ben)約921.5萬元，三元鹽(yan)蒸汽發生系統(tong)熔(rong)(rong)鹽(yan)儲罐的建的投(tou)(tou)資成(cheng)本(ben)(ben)約1115.5萬元，比二元鹽(yan)系統(tong)高(gao)194.0萬元。

表1中給出(chu)了調研得到的二(er)元(yuan)鹽(yan)(yan)(yan)和三元(yuan)鹽(yan)(yan)(yan)的市(shi)場價格區間，取平(ping)均值對(dui)應二(er)元(yuan)鹽(yan)(yan)(yan)和三元(yuan)鹽(yan)(yan)(yan)的價格分(fen)別為7000元(yuan)/t和7500元(yuan)/t。根(gen)據熔(rong)鹽(yan)(yan)(yan)的用量，最(zui)終(zhong)確(que)定二(er)元(yuan)鹽(yan)(yan)(yan)蒸汽發(fa)(fa)生系統熔(rong)鹽(yan)(yan)(yan)成(cheng)本(ben)為1190.0萬(wan)元(yuan)，二(er)元(yuan)鹽(yan)(yan)(yan)蒸汽發(fa)(fa)生系統熔(rong)鹽(yan)(yan)(yan)成(cheng)本(ben)為1875.0萬(wan)元(yuan)，比二(er)元(yuan)鹽(yan)(yan)(yan)系統高685萬(wan)元(yuan)。

熔(rong)鹽(yan)(yan)(yan)(yan)(yan)(yan)蒸(zheng)(zheng)(zheng)汽(qi)(qi)發(fa)(fa)(fa)生(sheng)(sheng)系(xi)(xi)統(tong)(tong)涉及的(de)(de)(de)動力(li)(li)設備(bei)主(zhu)(zhu)要(yao)包括熱(re)鹽(yan)(yan)(yan)(yan)(yan)(yan)泵(beng)(beng)(beng)和給(gei)水(shui)(shui)泵(beng)(beng)(beng)，其中熱(re)鹽(yan)(yan)(yan)(yan)(yan)(yan)泵(beng)(beng)(beng)布(bu)置在熱(re)鹽(yan)(yan)(yan)(yan)(yan)(yan)罐出口，主(zhu)(zhu)要(yao)用于給(gei)熔(rong)鹽(yan)(yan)(yan)(yan)(yan)(yan)汽(qi)(qi)水(shui)(shui)換熱(re)器(qi)輸送(song)熱(re)鹽(yan)(yan)(yan)(yan)(yan)(yan)，給(gei)水(shui)(shui)泵(beng)(beng)(beng)用于將除氧(yang)器(qi)的(de)(de)(de)給(gei)水(shui)(shui)泵(beng)(beng)(beng)送(song)至熔(rong)鹽(yan)(yan)(yan)(yan)(yan)(yan)蒸(zheng)(zheng)(zheng)汽(qi)(qi)發(fa)(fa)(fa)生(sheng)(sheng)系(xi)(xi)統(tong)(tong)。泵(beng)(beng)(beng)的(de)(de)(de)流(liu)量(liang)、工質(zhi)(zhi)、壓(ya)力(li)(li)等(deng)是影(ying)響熱(re)鹽(yan)(yan)(yan)(yan)(yan)(yan)泵(beng)(beng)(beng)和給(gei)水(shui)(shui)泵(beng)(beng)(beng)造價的(de)(de)(de)主(zhu)(zhu)要(yao)因素(su)。參考(kao)由(you)SNL、DOE和NREL共同(tong)完成(cheng)(cheng)的(de)(de)(de)技術路(lu)線(xian)報告，熱(re)鹽(yan)(yan)(yan)(yan)(yan)(yan)泵(beng)(beng)(beng)的(de)(de)(de)造價將隨著系(xi)(xi)統(tong)(tong)存儲能量(liang)容量(liang)的(de)(de)(de)增加而增加，熱(re)熔(rong)鹽(yan)(yan)(yan)(yan)(yan)(yan)泵(beng)(beng)(beng)的(de)(de)(de)價格為(wei)40元(yuan)(yuan)/kWth，二元(yuan)(yuan)鹽(yan)(yan)(yan)(yan)(yan)(yan)和三元(yuan)(yuan)鹽(yan)(yan)(yan)(yan)(yan)(yan)蒸(zheng)(zheng)(zheng)汽(qi)(qi)發(fa)(fa)(fa)生(sheng)(sheng)系(xi)(xi)統(tong)(tong)輸出的(de)(de)(de)最大功率分別為(wei)136.5 MWth和165.8 MWth，因此二元(yuan)(yuan)鹽(yan)(yan)(yan)(yan)(yan)(yan)和三元(yuan)(yuan)鹽(yan)(yan)(yan)(yan)(yan)(yan)蒸(zheng)(zheng)(zheng)汽(qi)(qi)發(fa)(fa)(fa)生(sheng)(sheng)系(xi)(xi)統(tong)(tong)熱(re)鹽(yan)(yan)(yan)(yan)(yan)(yan)泵(beng)(beng)(beng)的(de)(de)(de)成(cheng)(cheng)本(ben)分別為(wei)546.0萬(wan)元(yuan)(yuan)和663.2萬(wan)元(yuan)(yuan)，比二元(yuan)(yuan)鹽(yan)(yan)(yan)(yan)(yan)(yan)系(xi)(xi)統(tong)(tong)高117.2萬(wan)元(yuan)(yuan)。熔(rong)鹽(yan)(yan)(yan)(yan)(yan)(yan)系(xi)(xi)統(tong)(tong)給(gei)水(shui)(shui)泵(beng)(beng)(beng)為(wei)較為(wei)成(cheng)(cheng)熟的(de)(de)(de)常規設備(bei)，經市場調研得(de)到二元(yuan)(yuan)鹽(yan)(yan)(yan)(yan)(yan)(yan)和三元(yuan)(yuan)鹽(yan)(yan)(yan)(yan)(yan)(yan)蒸(zheng)(zheng)(zheng)汽(qi)(qi)發(fa)(fa)(fa)生(sheng)(sheng)系(xi)(xi)統(tong)(tong)給(gei)水(shui)(shui)泵(beng)(beng)(beng)的(de)(de)(de)價位(wei)分別為(wei)150萬(wan)元(yuan)(yuan)和100萬(wan)元(yuan)(yuan)。綜上所(suo)述，二元(yuan)(yuan)鹽(yan)(yan)(yan)(yan)(yan)(yan)蒸(zheng)(zheng)(zheng)汽(qi)(qi)發(fa)(fa)(fa)生(sheng)(sheng)系(xi)(xi)統(tong)(tong)動力(li)(li)設備(bei)投(tou)資為(wei)696.0萬(wan)元(yuan)(yuan)，二元(yuan)(yuan)鹽(yan)(yan)(yan)(yan)(yan)(yan)蒸(zheng)(zheng)(zheng)汽(qi)(qi)發(fa)(fa)(fa)生(sheng)(sheng)系(xi)(xi)統(tong)(tong)動力(li)(li)設備(bei)投(tou)資為(wei)763.2萬(wan)元(yuan)(yuan)，比二元(yuan)(yuan)鹽(yan)(yan)(yan)(yan)(yan)(yan)系(xi)(xi)統(tong)(tong)高67.2萬(wan)元(yuan)(yuan)。根(gen)據管(guan)(guan)(guan)道(dao)(dao)(dao)的(de)(de)(de)流(liu)量(liang)、系(xi)(xi)統(tong)(tong)阻(zu)力(li)(li)考(kao)慮不(bu)同(tong)介(jie)質(zhi)(zhi)的(de)(de)(de)流(liu)速，液(ye)體流(liu)速2~4 m/s，蒸(zheng)(zheng)(zheng)汽(qi)(qi)10~20 m/s，計(ji)算(suan)不(bu)同(tong)管(guan)(guan)(guan)道(dao)(dao)(dao)的(de)(de)(de)管(guan)(guan)(guan)徑，再根(gen)據設計(ji)條件選取(qu)(qu)管(guan)(guan)(guan)道(dao)(dao)(dao)的(de)(de)(de)材(cai)質(zhi)(zhi)、計(ji)算(suan)管(guan)(guan)(guan)道(dao)(dao)(dao)壁(bi)厚。二元(yuan)(yuan)鹽(yan)(yan)(yan)(yan)(yan)(yan)蒸(zheng)(zheng)(zheng)汽(qi)(qi)發(fa)(fa)(fa)生(sheng)(sheng)系(xi)(xi)統(tong)(tong)設計(ji)溫度>400℃的(de)(de)(de)管(guan)(guan)(guan)道(dao)(dao)(dao)材(cai)質(zhi)(zhi)選取(qu)(qu)TP347H不(bu)銹(xiu)鋼，主(zhu)(zhu)蒸(zheng)(zheng)(zheng)汽(qi)(qi)管(guan)(guan)(guan)道(dao)(dao)(dao)選取(qu)(qu)12Cr1MoVG，其余管(guan)(guan)(guan)道(dao)(dao)(dao)為(wei)20G，三元(yuan)(yuan)鹽(yan)(yan)(yan)(yan)(yan)(yan)蒸(zheng)(zheng)(zheng)汽(qi)(qi)發(fa)(fa)(fa)生(sheng)(sheng)系(xi)(xi)統(tong)(tong)所(suo)有管(guan)(guan)(guan)道(dao)(dao)(dao)設計(ji)溫度均，管(guan)(guan)(guan)道(dao)(dao)(dao)材(cai)質(zhi)(zhi)選取(qu)(qu)20G。核(he)算(suan)得(de)到二元(yuan)(yuan)鹽(yan)(yan)(yan)(yan)(yan)(yan)比三元(yuan)(yuan)鹽(yan)(yan)(yan)(yan)(yan)(yan)蒸(zheng)(zheng)(zheng)汽(qi)(qi)發(fa)(fa)(fa)生(sheng)(sheng)系(xi)(xi)統(tong)(tong)管(guan)(guan)(guan)道(dao)(dao)(dao)投(tou)資成(cheng)(cheng)本(ben)增加~131萬(wan)元(yuan)(yuan)，詳見表3。

綜(zong)合考慮熔(rong)(rong)鹽(yan)(yan)(yan)蒸(zheng)(zheng)汽發(fa)(fa)生系(xi)(xi)(xi)(xi)統(tong)(tong)(tong)(tong)熔(rong)(rong)鹽(yan)(yan)(yan)側(ce)和(he)汽水側(ce)運行(xing)(xing)溫(wen)度(du)、介質流量(liang)/流速(su)、換熱(re)器(qi)(qi)(qi)熱(re)負(fu)(fu)荷、系(xi)(xi)(xi)(xi)統(tong)(tong)(tong)(tong)壓力(li)及支(zhi)撐升(sheng)負(fu)(fu)荷次(ci)數等邊(bian)界條(tiao)件(jian)，進行(xing)(xing)換熱(re)器(qi)(qi)(qi)、熔(rong)(rong)鹽(yan)(yan)(yan)儲罐、熔(rong)(rong)鹽(yan)(yan)(yan)用量(liang)、動力(li)設(she)備和(he)管道(dao)尺(chi)寸(cun)、材(cai)質的(de)(de)設(she)計(ji)計(ji)算。二(er)(er)元(yuan)(yuan)鹽(yan)(yan)(yan)和(he)三元(yuan)(yuan)鹽(yan)(yan)(yan)蒸(zheng)(zheng)汽發(fa)(fa)生系(xi)(xi)(xi)(xi)統(tong)(tong)(tong)(tong)換熱(re)器(qi)(qi)(qi)面積(ji)和(he)主要投資對(dui)(dui)比(bi)如(ru)圖11所(suo)示(shi)，受限于不同種類熔(rong)(rong)鹽(yan)(yan)(yan)運行(xing)(xing)溫(wen)度(du)、熔(rong)(rong)鹽(yan)(yan)(yan)系(xi)(xi)(xi)(xi)統(tong)(tong)(tong)(tong)發(fa)(fa)電(dian)(dian)效率等，相同發(fa)(fa)電(dian)(dian)量(liang)對(dui)(dui)應(ying)二(er)(er)元(yuan)(yuan)鹽(yan)(yan)(yan)蒸(zheng)(zheng)汽發(fa)(fa)生系(xi)(xi)(xi)(xi)統(tong)(tong)(tong)(tong)的(de)(de)熱(re)負(fu)(fu)荷低，換熱(re)器(qi)(qi)(qi)面積(ji)為(wei)2090.6 m2，僅為(wei)三元(yuan)(yuan)鹽(yan)(yan)(yan)蒸(zheng)(zheng)汽發(fa)(fa)生系(xi)(xi)(xi)(xi)統(tong)(tong)(tong)(tong)換熱(re)器(qi)(qi)(qi)面積(ji)的(de)(de)~0.38倍(bei)(bei)(如(ru)圖11a)，三元(yuan)(yuan)鹽(yan)(yan)(yan)蒸(zheng)(zheng)汽發(fa)(fa)生系(xi)(xi)(xi)(xi)統(tong)(tong)(tong)(tong)換熱(re)器(qi)(qi)(qi)的(de)(de)投資成(cheng)本(ben)(ben)高于二(er)(er)元(yuan)(yuan)鹽(yan)(yan)(yan)。此外，二(er)(er)元(yuan)(yuan)鹽(yan)(yan)(yan)蒸(zheng)(zheng)汽發(fa)(fa)生系(xi)(xi)(xi)(xi)統(tong)(tong)(tong)(tong)管道(dao)投資大于三元(yuan)(yuan)鹽(yan)(yan)(yan)蒸(zheng)(zheng)汽發(fa)(fa)生系(xi)(xi)(xi)(xi)統(tong)(tong)(tong)(tong)，三元(yuan)(yuan)鹽(yan)(yan)(yan)蒸(zheng)(zheng)汽發(fa)(fa)生系(xi)(xi)(xi)(xi)統(tong)(tong)(tong)(tong)熔(rong)(rong)鹽(yan)(yan)(yan)投資約(yue)為(wei)二(er)(er)元(yuan)(yuan)鹽(yan)(yan)(yan)的(de)(de)1.5倍(bei)(bei)，熔(rong)(rong)鹽(yan)(yan)(yan)儲罐的(de)(de)投資成(cheng)本(ben)(ben)約(yue)是二(er)(er)元(yuan)(yuan)鹽(yan)(yan)(yan)的(de)(de)1.2倍(bei)(bei)，動力(li)設(she)備的(de)(de)投資成(cheng)本(ben)(ben)基(ji)本(ben)(ben)一致(如(ru)圖11b)。

綜上分析，二(er)元(yuan)(yuan)鹽(yan)(yan)蒸(zheng)汽發生系統主(zhu)要投資成(cheng)本~3526.8萬(wan)元(yuan)(yuan)，三元(yuan)(yuan)鹽(yan)(yan)蒸(zheng)汽發生系統主(zhu)要投資成(cheng)本~4525.1萬(wan)元(yuan)(yuan)，比二(er)元(yuan)(yuan)鹽(yan)(yan)蒸(zheng)汽發生系統高(gao)~1000萬(wan)元(yuan)(yuan)。

五、結論

本文以350 MW靈(ling)活(huo)燃煤發(fa)電機組(zu)為研究對象，提(ti)出可獨立承擔3%Pe/min升(sheng)負荷(he)速率(lv)(lv)的熔(rong)鹽(yan)(yan)系(xi)統。綜合(he)系(xi)統熱(re)力計算與(yu)設備傳熱(re)分(fen)析，對二元(yuan)鹽(yan)(yan)和三(san)元(yuan)鹽(yan)(yan)蒸汽發(fa)生(sheng)系(xi)統發(fa)電效率(lv)(lv)、系(xi)統復雜性及投(tou)資成(cheng)本進行對比研究，主要結論(lun)如(ru)下(xia)：

(1)相比于三元鹽(yan)，二元鹽(yan)分解溫度高，能產(chan)生較高品位蒸(zheng)汽，發電效率(lv)更高。設計工況(kuang)下三元鹽(yan)蒸(zheng)汽發生系統發電效率(lv)為29.2%，二元鹽(yan)蒸(zheng)汽發生系統發電效率(lv)達到(dao)36.7%，提(ti)高了7.5個百分點(dian)。

(2)相比(bi)于三元鹽(yan)，二元鹽(yan)熔點高，來自除氧器的給水需經過(guo)兩級抽汽(qi)預熱(re)，防止熔鹽(yan)在(zai)預熱(re)器中凝固堵塞，因此二元鹽(yan)蒸汽(qi)發生系統(tong)略復雜。

(3)相比(bi)于三元(yuan)鹽(yan)(yan)，二(er)元(yuan)鹽(yan)(yan)運(yun)行溫(wen)度(du)高，設備和(he)管道需要(yao)更貴(gui)的鋼材。然而，滿(man)足相同升(sheng)負荷(he)需求下，二(er)元(yuan)鹽(yan)(yan)用量少，相應熔鹽(yan)(yan)儲罐(guan)體積(ji)降(jiang)低(di)；其次，二(er)元(yuan)鹽(yan)(yan)蒸(zheng)汽(qi)發生(sheng)系統(tong)熱負荷(he)小(xiao)，換(huan)熱器面積(ji)減小(xiao)。綜合考(kao)慮上述因(yin)素二(er)元(yuan)鹽(yan)(yan)蒸(zheng)汽(qi)發生(sheng)系統(tong)投(tou)資成本更低(di)。

(4)為構建支撐靈(ling)活燃(ran)煤發電的高效、安全熔鹽(yan)系(xi)統(tong)，綜合(he)以上技術經濟性(xing)分析，本文建議在實際工(gong)程中采用二元鹽(yan)。