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摘要：儲能是新型電力系統的關鍵核心技術，熔鹽儲能作為一種中高溫傳熱蓄熱方法，因具有儲能密度高、穩定性好等優點，廣泛應用于太陽能光熱系統、調峰調頻、綠電消納等新能源領域。但目前對熔鹽儲能系統中的核心部件如儲罐、熔鹽電加熱器、熔鹽換熱器等設備的研究普遍基于太陽能熱發電技術的需求開展，針對其他應用場景的研究尚不夠充分。在不同應用場景下，熔鹽的使用溫度區間、加熱及換熱方式都有區別。概述了熔鹽儲能關鍵技術的研究現狀和技術成果，研究了熔鹽儲能技術的發展路徑，提出了其在新型電力系統中的應用領域，并針對不同應用場景，提出了相應的熔鹽選型參數、儲罐及換熱器類型。

引言：“雙碳(tan)”背景(jing)(jing)下(xia)，構建(jian)新(xin)型(xing)電(dian)(dian)力(li)(li)系(xi)統是(shi)保障我國能(neng)(neng)(neng)源(yuan)安(an)全的(de)戰(zhan)略任(ren)務。光伏光熱(re)(re)(re)、風電(dian)(dian)水力(li)(li)等新(xin)能(neng)(neng)(neng)源(yuan)存在間歇性(xing)和(he)(he)(he)不(bu)(bu)穩定性(xing)，易造成能(neng)(neng)(neng)源(yuan)供(gong)需不(bu)(bu)匹配，需要配合儲(chu)能(neng)(neng)(neng)技(ji)術。熔(rong)(rong)(rong)鹽儲(chu)熱(re)(re)(re)是(shi)一(yi)種安(an)全水平較高的(de)儲(chu)能(neng)(neng)(neng)方(fang)式，利用(yong)硝(xiao)酸鹽等熔(rong)(rong)(rong)鹽作(zuo)為傳熱(re)(re)(re)介質，通(tong)過熔(rong)(rong)(rong)鹽的(de)儲(chu)熱(re)(re)(re)和(he)(he)(he)放(fang)熱(re)(re)(re)循(xun)環來存儲(chu)和(he)(he)(he)放(fang)出能(neng)(neng)(neng)量，實現能(neng)(neng)(neng)量的(de)有效遷移。熔(rong)(rong)(rong)鹽儲(chu)能(neng)(neng)(neng)的(de)關鍵核心技(ji)術和(he)(he)(he)設備包(bao)括熔(rong)(rong)(rong)鹽、電(dian)(dian)加熱(re)(re)(re)器(qi)、儲(chu)罐以(yi)及換(huan)熱(re)(re)(re)器(qi)等，廣泛應(ying)(ying)用(yong)在以(yi)下(xia)3個(ge)方(fang)向：太陽能(neng)(neng)(neng)光熱(re)(re)(re)發電(dian)(dian)、耦(ou)合火電(dian)(dian)機組調(diao)(diao)(diao)峰(feng)調(diao)(diao)(diao)頻(pin)(pin)、耦(ou)合新(xin)能(neng)(neng)(neng)源(yuan)綠(lv)電(dian)(dian)供(gong)熱(re)(re)(re)。表1為熔(rong)(rong)(rong)鹽儲(chu)能(neng)(neng)(neng)不(bu)(bu)同(tong)應(ying)(ying)用(yong)場景(jing)(jing)對(dui)比。針(zhen)對(dui)不(bu)(bu)同(tong)應(ying)(ying)用(yong)場景(jing)(jing)，熔(rong)(rong)(rong)鹽的(de)使用(yong)溫度區間和(he)(he)(he)換(huan)熱(re)(re)(re)過程(cheng)均有較大差異。現階(jie)段以(yi)解決光熱(re)(re)(re)電(dian)(dian)站(zhan)的(de)技(ji)術需求為主，針(zhen)對(dui)熔(rong)(rong)(rong)鹽儲(chu)能(neng)(neng)(neng)耦(ou)合火電(dian)(dian)機組調(diao)(diao)(diao)峰(feng)調(diao)(diao)(diao)頻(pin)(pin)、綠(lv)電(dian)(dian)供(gong)熱(re)(re)(re)等領域的(de)系(xi)統性(xing)研(yan)究嚴重不(bu)(bu)足(zu)。

1、熔鹽儲能關鍵技術

現有熔鹽的(de)選型(xing)主要(yao)為耐高溫熔鹽和低(di)(di)熔點鹽。耐高溫熔鹽如技術成熟的(de)Solar鹽，最高工(gong)作溫度達565℃，適(shi)合于(yu)高參(can)(can)數光熱發電或火(huo)電機組儲熱調(diao)峰系(xi)統。低(di)(di)熔點鹽通常為多元混合鹽，熔點低(di)(di)于(yu)240℃，如工(gong)程中常用的(de)Hitec鹽等，能降(jiang)低(di)(di)熔鹽凝固的(de)風險，適(shi)用于(yu)較(jiao)低(di)(di)參(can)(can)數的(de)系(xi)統。

熔鹽儲罐主要有單罐、雙罐、多罐系統。單罐熔鹽儲能系統結構簡單，成本較低，適用于小面積生活供暖等領域，但存在斜溫層導致蓄熱效率降低的問題[1]。雙罐系統包含冷罐與熱罐，通過冷熱熔鹽分離并在2罐中循環換熱，避免了斜溫層問題，技術風險也相對較低。在雙罐的基礎上還可進一步增加儲罐數量，形成多罐系統，增大儲熱量。如哈密50 MW熔鹽塔式(shi)光熱發電(dian)項目(mu)首創了雙熱罐、一冷罐的(de)系統(tong)配置，提高了機組的(de)可靠性和(he)靈(ling)活(huo)性。

實現大規模熔鹽儲能的關鍵是兼具低成本、可實施性的高電壓等級熔鹽電加熱器的研發。目前，熔鹽電加熱器主要有電阻式、電極式、感應式3種形式。現有技術普遍為380 V或690 V的低壓電阻式加熱器，主要應用于光熱發電場景。若用于電加熱熔鹽的場景如綠電供熱，則存在高壓綠電輸入與低壓加熱器不匹配而產生較高變電成本的問題。目前，市面上總體缺乏成熟的高電壓熔鹽加熱器。

傳統的(de)熔鹽(yan)(yan)換(huan)(huan)熱(re)器(qi)(qi)(qi)有(you)管(guan)殼(ke)式(shi)(shi)換(huan)(huan)熱(re)器(qi)(qi)(qi)和套管(guan)式(shi)(shi)換(huan)(huan)熱(re)器(qi)(qi)(qi)。管(guan)殼(ke)式(shi)(shi)換(huan)(huan)熱(re)器(qi)(qi)(qi)是目(mu)前熔鹽(yan)(yan)換(huan)(huan)熱(re)器(qi)(qi)(qi)的(de)主要形式(shi)(shi)，許多(duo)研(yan)究者已通過實驗和計算給出了(le)推薦(jian)的(de)管(guan)程、殼(ke)程換(huan)(huan)熱(re)關聯式(shi)(shi)[2-3]，對其傳熱(re)特性進(jin)行了(le)數學描述。套管(guan)式(shi)(shi)換(huan)(huan)熱(re)器(qi)(qi)(qi)具有(you)結構(gou)簡單(dan)、能耐高(gao)(gao)壓的(de)優(you)點，在(zai)工(gong)程中也有(you)應用。與上(shang)述傳統換(huan)(huan)熱(re)器(qi)(qi)(qi)相比，以印刷電(dian)路板換(huan)(huan)熱(re)器(qi)(qi)(qi)為代表的(de)緊湊式(shi)(shi)換(huan)(huan)熱(re)器(qi)(qi)(qi)效率高(gao)(gao)且能承(cheng)受高(gao)(gao)溫、高(gao)(gao)壓工(gong)況，在(zai)新型電(dian)力系統如熔鹽(yan)(yan)儲能與新型動力循環的(de)耦合中具有(you)很大(da)優(you)勢[4]。表2整理(li)了(le)熔鹽(yan)(yan)關鍵技術的(de)對比、分類情(qing)況，以及不(bu)同(tong)的(de)應用場景(jing)下熔鹽(yan)(yan)、儲罐、加熱(re)器(qi)(qi)(qi)選(xuan)型的(de)區別。

2、熔鹽儲能在光熱領域的應用

太陽(yang)能(neng)(neng)光熱(re)發(fa)電是(shi)新型(xing)電力系統的(de)中堅力量，擁(yong)有并網無障(zhang)礙、連續發(fa)電調(diao)節(jie)能(neng)(neng)力強(qiang)的(de)優(you)勢(shi)。光熱(re)電站將(jiang)太陽(yang)能(neng)(neng)以熱(re)能(neng)(neng)的(de)形式存儲在熔(rong)鹽中，后續利用(yong)熔(rong)鹽加熱(re)給(gei)水獲取(qu)蒸(zheng)汽，優(you)勢(shi)在于儲能(neng)(neng)容量大，對地理環境要求(qiu)低(di)，建設規模可達10 GW以上。光熱(re)型(xing)熔(rong)鹽儲能(neng)(neng)電站的(de)技術研究重點是(shi)如何降低(di)其成本、提高安(an)全性(xing)。

大部分光熱(re)(re)(re)(re)(re)(re)電站使用熔(rong)(rong)(rong)鹽(yan)雙罐(guan)系(xi)(xi)統，光熱(re)(re)(re)(re)(re)(re)和(he)熔(rong)(rong)(rong)鹽(yan)的耦合形式分為(wei)間(jian)接和(he)直接2種。雙罐(guan)熔(rong)(rong)(rong)鹽(yan)儲熱(re)(re)(re)(re)(re)(re)系(xi)(xi)統如圖1所示[16-17]。間(jian)接蓄(xu)熱(re)(re)(re)(re)(re)(re)系(xi)(xi)統需(xu)要換(huan)熱(re)(re)(re)(re)(re)(re)裝置來傳遞熱(re)(re)(re)(re)(re)(re)量，采用導(dao)熱(re)(re)(re)(re)(re)(re)油(you)(you)或水蒸(zheng)氣作為(wei)傳熱(re)(re)(re)(re)(re)(re)流(liu)體，在(zai)熔(rong)(rong)(rong)鹽(yan)中蓄(xu)熱(re)(re)(re)(re)(re)(re)。間(jian)接蓄(xu)熱(re)(re)(re)(re)(re)(re)系(xi)(xi)統換(huan)熱(re)(re)(re)(re)(re)(re)過(guo)程為(wei)太(tai)陽(yang)能-熔(rong)(rong)(rong)鹽(yan)-導(dao)熱(re)(re)(re)(re)(re)(re)油(you)(you)-蒸(zheng)汽(qi)，熔(rong)(rong)(rong)鹽(yan)中儲存(cun)的熱(re)(re)(re)(re)(re)(re)能通過(guo)導(dao)熱(re)(re)(re)(re)(re)(re)油(you)(you)循(xun)環，到達蒸(zheng)汽(qi)發(fa)生器換(huan)熱(re)(re)(re)(re)(re)(re)。間(jian)接蓄(xu)熱(re)(re)(re)(re)(re)(re)系(xi)(xi)統中熔(rong)(rong)(rong)鹽(yan)儲能系(xi)(xi)統作為(wei)相(xiang)對獨立的模(mo)塊存(cun)在(zai)，可用于(yu)(yu)改(gai)造普(pu)通光熱(re)(re)(re)(re)(re)(re)電站。因導(dao)熱(re)(re)(re)(re)(re)(re)油(you)(you)的熱(re)(re)(re)(re)(re)(re)穩定性不足，間(jian)接蓄(xu)熱(re)(re)(re)(re)(re)(re)的工(gong)作溫(wen)度一般規定在(zai)400℃以下。直接蓄(xu)熱(re)(re)(re)(re)(re)(re)系(xi)(xi)統采用熔(rong)(rong)(rong)鹽(yan)作為(wei)傳熱(re)(re)(re)(re)(re)(re)和(he)蓄(xu)熱(re)(re)(re)(re)(re)(re)介質，其換(huan)熱(re)(re)(re)(re)(re)(re)過(guo)程為(wei)太(tai)陽(yang)能-熔(rong)(rong)(rong)鹽(yan)-蒸(zheng)汽(qi)，不需(xu)要經(jing)過(guo)導(dao)熱(re)(re)(re)(re)(re)(re)油(you)(you)循(xun)環，避免了不良換(huan)熱(re)(re)(re)(re)(re)(re)，適用于(yu)(yu)400～500℃的高溫(wen)工(gong)況，也可提高電站效率(lv)和(he)朗肯循(xun)環效率(lv)。

光(guang)熱(re)(re)(re)(re)與熔(rong)鹽(yan)耦合的(de)2種(zhong)形式(shi)(shi)在工(gong)(gong)程中均(jun)有應用。熔(rong)鹽(yan)間(jian)接(jie)(jie)(jie)蓄(xu)(xu)(xu)熱(re)(re)(re)(re)一般能保持較(jiao)高的(de)循環(huan)效率(lv)，比蒸汽蓄(xu)(xu)(xu)能成本更低(di)[16]，如西班牙(ya)Andasol槽式(shi)(shi)光(guang)熱(re)(re)(re)(re)電(dian)站是第一個大(da)規模熔(rong)鹽(yan)間(jian)接(jie)(jie)(jie)蓄(xu)(xu)(xu)熱(re)(re)(re)(re)電(dian)站，容量約為(wei)1000 MW·h，儲能時間(jian)為(wei)7.5 h。熔(rong)鹽(yan)直接(jie)(jie)(jie)蓄(xu)(xu)(xu)熱(re)(re)(re)(re)簡化了電(dian)站設備組成，后(hou)期運維(wei)便捷。典型的(de)熔(rong)鹽(yan)直接(jie)(jie)(jie)蓄(xu)(xu)(xu)熱(re)(re)(re)(re)電(dian)站是美國Solar two項目(mu)，該項目(mu)使用的(de)硝酸(suan)鹽(yan)混合鹽(yan)被稱作(zuo)(zuo)Solar鹽(yan)，溫度范圍(wei)290~565℃。此后(hou)的(de)塔式(shi)(shi)熔(rong)鹽(yan)光(guang)熱(re)(re)(re)(re)電(dian)站多沿用直接(jie)(jie)(jie)蓄(xu)(xu)(xu)熱(re)(re)(re)(re)方式(shi)(shi)與此工(gong)(gong)作(zuo)(zuo)溫度區間(jian)，如西班牙(ya)Gemasolar電(dian)廠、青海中控德(de)令哈10 MW項目(mu)。

未來光熱(re)(re)(re)的(de)發展主要(yao)(yao)在(zai)于高(gao)(gao)(gao)參(can)(can)(can)數(shu)(shu)運(yun)行及(ji)(ji)(ji)耦合(he)(he)新(xin)型(xing)動(dong)力(li)循(xun)(xun)(xun)環(huan)。高(gao)(gao)(gao)參(can)(can)(can)數(shu)(shu)運(yun)行涉(she)及(ji)(ji)(ji)的(de)關鍵技(ji)術(shu)為耐高(gao)(gao)(gao)溫(wen)熔(rong)鹽(yan)(yan)(yan)(yan)，選用碳(tan)酸鹽(yan)(yan)(yan)(yan)和部分MgCl2-KCl-NaCl混合(he)(he)體(ti)系(xi)的(de)氯化鹽(yan)(yan)(yan)(yan)可提(ti)高(gao)(gao)(gao)系(xi)統(tong)的(de)整體(ti)效率。光熱(re)(re)(re)耦合(he)(he)新(xin)型(xing)動(dong)力(li)循(xun)(xun)(xun)環(huan)則(ze)主要(yao)(yao)及(ji)(ji)(ji)高(gao)(gao)(gao)參(can)(can)(can)數(shu)(shu)熔(rong)鹽(yan)(yan)(yan)(yan)及(ji)(ji)(ji)熔(rong)鹽(yan)(yan)(yan)(yan)換(huan)(huan)熱(re)(re)(re)器，以(yi)超臨界CO2（S-CO2）布雷頓(dun)循(xun)(xun)(xun)環(huan)光熱(re)(re)(re)發電系(xi)統(tong)為例，其(qi)中最高(gao)(gao)(gao)工(gong)作溫(wen)度(du)可達(da)800℃，冷熱(re)(re)(re)罐熔(rong)鹽(yan)(yan)(yan)(yan)的(de)溫(wen)差將達(da)到100~120℃，儲能的(de)難度(du)更大(da)[18]，需(xu)要(yao)(yao)使用性(xing)能穩定的(de)寬溫(wen)域高(gao)(gao)(gao)參(can)(can)(can)數(shu)(shu)熔(rong)鹽(yan)(yan)(yan)(yan)。該系(xi)統(tong)參(can)(can)(can)數(shu)(shu)高(gao)(gao)(gao)、效率高(gao)(gao)(gao)、部件緊湊(cou)，涉(she)及(ji)(ji)(ji)的(de)熔(rong)鹽(yan)(yan)(yan)(yan)-CO2換(huan)(huan)熱(re)(re)(re)器需(xu)耐受(shou)苛刻工(gong)況。在(zai)熔(rong)鹽(yan)(yan)(yan)(yan)-CO2換(huan)(huan)熱(re)(re)(re)領域可選擇(ze)緊湊(cou)式換(huan)(huan)熱(re)(re)(re)器如印刷電路(lu)板(ban)換(huan)(huan)熱(re)(re)(re)器[4]，換(huan)(huan)熱(re)(re)(re)效率高(gao)(gao)(gao)，能承受(shou)高(gao)(gao)(gao)達(da)30 MPa的(de)高(gao)(gao)(gao)溫(wen)、高(gao)(gao)(gao)壓(ya)(ya)工(gong)況。印刷電路(lu)板(ban)換(huan)(huan)熱(re)(re)(re)器用于熔(rong)鹽(yan)(yan)(yan)(yan)儲能和CO2循(xun)(xun)(xun)環(huan)已有研究。Wang等人[15]設計并制(zhi)造了一種翼(yi)形肋(lei)片(pian)印刷電路(lu)板(ban)換(huan)(huan)熱(re)(re)(re)器，在(zai)工(gong)作壓(ya)(ya)力(li)較(jiao)小的(de)熔(rong)鹽(yan)(yan)(yan)(yan)系(xi)統(tong)中采用換(huan)(huan)熱(re)(re)(re)性(xing)能較(jiao)好(hao)的(de)肋(lei)片(pian)強化換(huan)(huan)熱(re)(re)(re)通(tong)道。張虎忠[19]搭建(jian)了最高(gao)(gao)(gao)壓(ya)(ya)力(li)和溫(wen)度(du)分別為32 MPa和600℃的(de)S-CO2換(huan)(huan)熱(re)(re)(re)器試驗平臺，深(shen)度(du)掌(zhang)握(wo)了S-CO2在(zai)印刷電路(lu)板(ban)換(huan)(huan)熱(re)(re)(re)器中的(de)流動(dong)換(huan)(huan)熱(re)(re)(re)特性(xing)。

光熱(re)(re)發(fa)電(dian)中，塔(ta)(ta)式(shi)通過吸熱(re)(re)塔(ta)(ta)吸收聚集(ji)的太陽能(neng)(neng)，傳(chuan)熱(re)(re)至(zhi)熱(re)(re)罐(guan)；槽(cao)式(shi)通過集(ji)熱(re)(re)管收集(ji)太陽能(neng)(neng)；線性菲涅爾式(shi)光熱(re)(re)發(fa)電(dian)成(cheng)本低(di)，在(zai)我國西部擁(yong)有(you)良好的商業化前(qian)景(jing)；S-CO2用于光熱(re)(re)系統(tong)具(ju)有(you)循(xun)環效(xiao)率(lv)高、結構緊湊的優勢(shi)。光熱(re)(re)發(fa)電(dian)加(jia)熱(re)(re)器一(yi)般為低(di)壓電(dian)阻式(shi)，以(yi)較(jiao)低(di)的成(cheng)本滿足需求。除加(jia)熱(re)(re)器外，不同技術(shu)路線涉及的熔(rong)鹽儲能(neng)(neng)技術(shu)存在(zai)的區(qu)別見表3。

3、熔鹽儲能在火電調峰領域的應用

在火(huo)電(dian)機組(zu)(zu)中采用(yong)(yong)(yong)儲(chu)(chu)能(neng)(neng)可以(yi)實現削(xue)峰(feng)填谷，目前已經(jing)可以(yi)實現工程應(ying)用(yong)(yong)(yong)的(de)(de)是高溫熔(rong)(rong)(rong)(rong)鹽(yan)(yan)儲(chu)(chu)熱(re)耦(ou)(ou)合(he)火(huo)電(dian)機組(zu)(zu)調(diao)峰(feng)技術(shu)[20]。熔(rong)(rong)(rong)(rong)鹽(yan)(yan)-火(huo)電(dian)耦(ou)(ou)合(he)系統的(de)(de)優(you)勢在于能(neng)(neng)極大地提高機組(zu)(zu)深(shen)度(du)調(diao)峰(feng)和提供高溫蒸(zheng)(zheng)汽(qi)的(de)(de)能(neng)(neng)力(li)。熔(rong)(rong)(rong)(rong)鹽(yan)(yan)-火(huo)電(dian)耦(ou)(ou)合(he)形式(shi)多樣，如抽取部分主(zhu)蒸(zheng)(zheng)汽(qi)和再熱(re)蒸(zheng)(zheng)汽(qi)進入(ru)熔(rong)(rong)(rong)(rong)鹽(yan)(yan)儲(chu)(chu)能(neng)(neng)模塊(kuai)實現蒸(zheng)(zheng)汽(qi)蓄熱(re)；用(yong)(yong)(yong)發電(dian)機出口(kou)電(dian)力(li)加熱(re)熔(rong)(rong)(rong)(rong)鹽(yan)(yan)的(de)(de)電(dian)加熱(re)；通過(guo)煙氣-熔(rong)(rong)(rong)(rong)鹽(yan)(yan)換熱(re)器實現的(de)(de)煙氣蓄熱(re)以(yi)及(ji)結合(he)以(yi)上幾(ji)種耦(ou)(ou)合(he)形式(shi)的(de)(de)混合(he)型加熱(re)。為提高熔(rong)(rong)(rong)(rong)鹽(yan)(yan)-蒸(zheng)(zheng)汽(qi)換熱(re)效率、增加儲(chu)(chu)能(neng)(neng)時長，火(huo)電(dian)調(diao)峰(feng)領域主(zhu)要涉(she)及(ji)高參數(shu)、寬(kuan)溫域的(de)(de)熔(rong)(rong)(rong)(rong)鹽(yan)(yan)選(xuan)型以(yi)及(ji)安(an)全穩(wen)定的(de)(de)雙罐(guan)熔(rong)(rong)(rong)(rong)鹽(yan)(yan)系統。

3.1蒸汽蓄熱

3.1.1再熱(re)蒸汽加熱(re)熔(rong)鹽(yan)

在火電(dian)機(ji)組正常運行的(de)同(tong)時抽(chou)(chou)取(qu)高(gao)壓主蒸(zheng)汽(qi)(qi)和(he)再(zai)熱(re)(re)(re)(re)蒸(zheng)汽(qi)(qi)加(jia)(jia)熱(re)(re)(re)(re)熔(rong)鹽(yan)(yan)，該耦(ou)合系(xi)(xi)統(tong)(tong)能夠提(ti)高(gao)調峰(feng)性(xing)能和(he)全過程循環效(xiao)(xiao)率，主要適用(yong)于亞臨界一次再(zai)熱(re)(re)(re)(re)機(ji)組500~600℃水平的(de)蒸(zheng)汽(qi)(qi)蓄熱(re)(re)(re)(re)。羅海華等[21]通過計算證明了再(zai)熱(re)(re)(re)(re)蒸(zheng)汽(qi)(qi)加(jia)(jia)熱(re)(re)(re)(re)熔(rong)鹽(yan)(yan)方案的(de)可(ke)行性(xing)，該方案利用(yong)熔(rong)鹽(yan)(yan)存(cun)儲的(de)熱(re)(re)(re)(re)量(liang)加(jia)(jia)熱(re)(re)(re)(re)給(gei)水，輸出工(gong)業蒸(zheng)汽(qi)(qi)，能實現火電(dian)機(ji)組熱(re)(re)(re)(re)電(dian)解(jie)耦(ou)和(he)供(gong)熱(re)(re)(re)(re)調峰(feng)。熔(rong)鹽(yan)(yan)-火電(dian)耦(ou)合也可(ke)存(cun)在多個抽(chou)(chou)汽(qi)(qi)點，范慶偉(wei)等[10]以(yi)600 MW機(ji)組為例，提(ti)出多罐(guan)-多換熱(re)(re)(re)(re)器(qi)(qi)儲熱(re)(re)(re)(re)系(xi)(xi)統(tong)(tong)，將再(zai)熱(re)(re)(re)(re)蒸(zheng)汽(qi)(qi)分別引入2個加(jia)(jia)熱(re)(re)(re)(re)器(qi)(qi)，其中疏水段加(jia)(jia)熱(re)(re)(re)(re)器(qi)(qi)的(de)?效(xiao)(xiao)率最高(gao)。

3.1.2再熱+過(guo)熱蒸汽加熱熔鹽

同時抽取再熱(re)、過熱(re)蒸汽(qi)與熔鹽(yan)(yan)換熱(re)的(de)技術路線(xian)能(neng)(neng)夠充(chong)分利用鍋(guo)爐所(suo)產生(sheng)的(de)高(gao)溫蒸汽(qi)，適用主蒸汽(qi)溫度為(wei)500～600℃。王輝等[22]設(she)計了火(huo)電機(ji)組(zu)超(chao)臨界百(bai)兆瓦級熔鹽(yan)(yan)儲能(neng)(neng)工(gong)藝(yi)流程，具體流程如圖2所(suo)示(shi)。其中，冷(leng)罐熔鹽(yan)(yan)預熱(re)后(hou)分成(cheng)2路，分別進入過熱(re)加熱(re)器(qi)和再熱(re)加熱(re)器(qi)，2路混合后(hou)進入熱(re)鹽(yan)(yan)罐，實現(xian)熔鹽(yan)(yan)回(hui)路的(de)流動儲熱(re)。該(gai)方案(an)各工(gong)藝(yi)模塊均為(wei)閉式循環，在(zai)全過程中鍋(guo)爐和汽(qi)輪機(ji)的(de)高(gao)溫工(gong)質(zhi)沒有減少或浪(lang)費(fei)，能(neng)(neng)極大(da)提高(gao)深(shen)度調峰能(neng)(neng)力和系統(tong)靈活性[23]。

3.1.3高(gao)再冷段蒸汽加熱熔鹽

抽取再(zai)(zai)熱(re)(re)蒸汽(qi)加熱(re)(re)熔鹽可(ke)(ke)能導致(zhi)再(zai)(zai)熱(re)(re)溫度(du)超限(xian)，采(cai)用(yong)具有煙氣再(zai)(zai)循環的二(er)次(ci)(ci)(ci)(ci)再(zai)(zai)熱(re)(re)機(ji)(ji)組(zu)(zu)(zu)(zu)可(ke)(ke)避免上(shang)述問題(ti)。該技術(shu)路(lu)線(xian)適(shi)用(yong)于(yu)主蒸汽(qi)溫度(du)600～620℃的二(er)次(ci)(ci)(ci)(ci)再(zai)(zai)熱(re)(re)機(ji)(ji)組(zu)(zu)(zu)(zu)。在上(shang)述機(ji)(ji)組(zu)(zu)(zu)(zu)中(zhong)抽取高(gao)再(zai)(zai)冷段(duan)蒸汽(qi)加熱(re)(re)熔鹽，所儲熱(re)(re)能可(ke)(ke)用(yong)于(yu)加熱(re)(re)給(gei)水，供熱(re)(re)或供工業(ye)蒸汽(qi)，提(ti)高(gao)機(ji)(ji)組(zu)(zu)(zu)(zu)靈活性(xing)。張世剛[24]以某超超臨界660 MW二(er)次(ci)(ci)(ci)(ci)再(zai)(zai)熱(re)(re)機(ji)(ji)組(zu)(zu)(zu)(zu)為研(yan)究對(dui)象，提(ti)出(chu)同時抽取一次(ci)(ci)(ci)(ci)和二(er)次(ci)(ci)(ci)(ci)高(gao)再(zai)(zai)冷段(duan)高(gao)溫蒸汽(qi)進行(xing)熔鹽蓄(xu)熱(re)(re)。龐力平等[25]則模擬(ni)了二(er)次(ci)(ci)(ci)(ci)再(zai)(zai)熱(re)(re)機(ji)(ji)組(zu)(zu)(zu)(zu)鍋(guo)爐(lu)和汽(qi)輪機(ji)(ji)的負荷響應特性(xing)，結果表明高(gao)再(zai)(zai)冷段(duan)蒸汽(qi)用(yong)于(yu)熔鹽蓄(xu)熱(re)(re)，可(ke)(ke)提(ti)高(gao)二(er)次(ci)(ci)(ci)(ci)再(zai)(zai)熱(re)(re)機(ji)(ji)組(zu)(zu)(zu)(zu)對(dui)電(dian)網(wang)負荷的響應速率。

3.1.4直接蒸汽蓄熱技術

針(zhen)對超超臨(lin)界機組620℃以(yi)上的(de)(de)蒸汽蓄(xu)熱(re)(re)，就(jiu)需要采用直接(jie)蒸汽蓄(xu)熱(re)(re)（direct steam generation，DSG）技術(shu)(shu)。DSG電站(zhan)中僅產出飽和(he)(he)蒸汽，無法采用常規的(de)(de)熔鹽(yan)冷、熱(re)(re)罐(guan)倒換(huan)運行(xing)模式，缺乏(fa)合(he)適的(de)(de)長時間(jian)大規模儲(chu)(chu)熱(re)(re)系(xi)(xi)統。為解(jie)決DSG技術(shu)(shu)的(de)(de)瓶頸，可(ke)采用高(gao)參數(shu)熔鹽(yan)技術(shu)(shu)和(he)(he)多罐(guan)熔鹽(yan)系(xi)(xi)統來組成DSG的(de)(de)儲(chu)(chu)能裝置(zhi)。如Seitz等(deng)人[26]在(zai)DSG系(xi)(xi)統中耦合(he)冷、熱(re)(re)、中間(jian)罐(guan)3罐(guan)熔鹽(yan)儲(chu)(chu)能，間(jian)接(jie)存儲(chu)(chu)給水蒸發的(de)(de)熱(re)(re)量，進行(xing)預熱(re)(re)和(he)(he)過熱(re)(re)加熱(re)(re)。Disor項目[27]使用熔點為306℃的(de)(de)硝酸鈉熔鹽(yan)作為介質(zhi)，直接(jie)與(yu)水蒸氣進行(xing)換(huan)熱(re)(re)。此類特殊(shu)情況涉(she)及高(gao)參數(shu)熔鹽(yan)，對熔鹽(yan)熱(re)(re)穩定性的(de)(de)要求較高(gao)。

3.1.5蒸(zheng)汽加熱熔鹽的不同情況(kuang)

在主(zhu)蒸汽(qi)蓄熱(re)和(he)再熱(re)蒸汽(qi)蓄熱(re)領(ling)域，熔(rong)鹽的選型存在區別。再熱(re)蒸汽(qi)壓力(li)參數(shu)較(jiao)低(di)，一般約(yue)為4 MPa，對應飽和(he)蒸汽(qi)溫(wen)(wen)度約(yue)251℃。高溫(wen)(wen)主(zhu)蒸汽(qi)和(he)再熱(re)蒸汽(qi)分別在不同熔(rong)點的熔(rong)鹽中蓄熱(re)的情況如圖3所示。

由圖3a)可見，由于點a處夾(jia)點溫(wen)(wen)(wen)(wen)(wen)度(du)的(de)存(cun)在(zai)(zai)，熔鹽被(bei)加(jia)(jia)(jia)熱(re)的(de)溫(wen)(wen)(wen)(wen)(wen)度(du)受(shou)到熔鹽最(zui)低(di)(di)使用(yong)溫(wen)(wen)(wen)(wen)(wen)度(du)和夾(jia)點溫(wen)(wen)(wen)(wen)(wen)度(du)的(de)限制，其使用(yong)溫(wen)(wen)(wen)(wen)(wen)度(du)范圍(wei)有限。常見的(de)低(di)(di)熔點熔鹽使用(yong)溫(wen)(wen)(wen)(wen)(wen)度(du)范圍(wei)為(wei)140~450℃，受(shou)到夾(jia)點溫(wen)(wen)(wen)(wen)(wen)度(du)影(ying)響(xiang)，其最(zui)高(gao)溫(wen)(wen)(wen)(wen)(wen)度(du)僅(jin)能被(bei)加(jia)(jia)(jia)熱(re)至(zhi)400℃左右(you)。若降低(di)(di)熔點，選(xuan)擇熔點在(zai)(zai)100℃左右(you)的(de)熔鹽，其使用(yong)溫(wen)(wen)(wen)(wen)(wen)度(du)上(shang)限就可以(yi)提(ti)升(sheng)至(zhi)450℃，但此(ci)(ci)類(lei)熔鹽的(de)應用(yong)研究尚不充(chong)分，工(gong)程實(shi)際(ji)中使用(yong)較少。若采(cai)用(yong)常規Solar鹽，其使用(yong)溫(wen)(wen)(wen)(wen)(wen)度(du)為(wei)260~565℃，此(ci)(ci)時熔鹽最(zui)低(di)(di)工(gong)作溫(wen)(wen)(wen)(wen)(wen)度(du)已經接近飽和蒸汽(qi)線(xian)，被(bei)再熱(re)蒸汽(qi)加(jia)(jia)(jia)熱(re)的(de)空間較小，并不適用(yong)于該場景(jing)。綜上(shang)所述，在(zai)(zai)再熱(re)蒸汽(qi)蓄熱(re)的(de)情景(jing)下，宜(yi)采(cai)用(yong)熔點較低(di)(di)的(de)熔鹽，其最(zui)高(gao)使用(yong)溫(wen)(wen)(wen)(wen)(wen)度(du)無需(xu)設置過(guo)高(gao)。

與之相反，主(zhu)(zhu)蒸(zheng)(zheng)(zheng)汽(qi)(qi)(qi)的(de)(de)參數(shu)較(jiao)(jiao)高(gao)，以(yi)14 MPa主(zhu)(zhu)蒸(zheng)(zheng)(zheng)汽(qi)(qi)(qi)為例，對(dui)(dui)(dui)應飽(bao)和蒸(zheng)(zheng)(zheng)汽(qi)(qi)(qi)溫(wen)度(du)約335℃，如圖3b)點(dian)(dian)(dian)b，其夾(jia)點(dian)(dian)(dian)位置相對(dui)(dui)(dui)更高(gao)，對(dui)(dui)(dui)熔(rong)鹽(yan)加熱(re)的(de)(de)限制相對(dui)(dui)(dui)較(jiao)(jiao)小。圖3b)描述了同(tong)一參數(shu)的(de)(de)主(zhu)(zhu)蒸(zheng)(zheng)(zheng)汽(qi)(qi)(qi)加熱(re)不同(tong)參數(shu)熔(rong)鹽(yan)的(de)(de)情況(kuang)，此(ci)時常見(jian)的(de)(de)低(di)熔(rong)點(dian)(dian)(dian)熔(rong)鹽(yan)工作(zuo)溫(wen)度(du)范圍為140~450℃，最高(gao)溫(wen)度(du)可進(jin)一步拓展，而Solar鹽(yan)工作(zuo)溫(wen)度(du)約260~565℃，在此(ci)蒸(zheng)(zheng)(zheng)汽(qi)(qi)(qi)參數(shu)下,只能被(bei)加熱(re)到420℃左右，若降(jiang)低(di)熔(rong)點(dian)(dian)(dian)，則熔(rong)鹽(yan)甚至可被(bei)加熱(re)到530℃以(yi)上。由此(ci)可見(jian)，針對(dui)(dui)(dui)主(zhu)(zhu)蒸(zheng)(zheng)(zheng)汽(qi)(qi)(qi)蓄熱(re)供熱(re)場(chang)景，常規熔(rong)鹽(yan)即(ji)可適(shi)用，但是對(dui)(dui)(dui)于主(zhu)(zhu)蒸(zheng)(zheng)(zheng)汽(qi)(qi)(qi)蓄熱(re)后還要再產生蒸(zheng)(zheng)(zheng)汽(qi)(qi)(qi)的(de)(de)熔(rong)鹽(yan)蓄熱(re)場(chang)景，適(shi)用于熔(rong)點(dian)(dian)(dian)較(jiao)(jiao)低(di)但是最高(gao)溫(wen)度(du)較(jiao)(jiao)高(gao)的(de)(de)寬(kuan)溫(wen)域熔(rong)鹽(yan)。

3.2發電(dian)機出(chu)口電(dian)加熱熔鹽

發(fa)電(dian)(dian)(dian)(dian)(dian)(dian)(dian)機出口(kou)電(dian)(dian)(dian)(dian)(dian)(dian)(dian)加熱(re)(re)(re)熔(rong)(rong)(rong)鹽技術路線是(shi)利用電(dian)(dian)(dian)(dian)(dian)(dian)(dian)廠發(fa)電(dian)(dian)(dian)(dian)(dian)(dian)(dian)機出口(kou)的(de)高(gao)(gao)壓電(dian)(dian)(dian)(dian)(dian)(dian)(dian)加熱(re)(re)(re)熔(rong)(rong)(rong)鹽，將儲(chu)存的(de)熱(re)(re)(re)能(neng)輸(shu)出為調峰電(dian)(dian)(dian)(dian)(dian)(dian)(dian)能(neng)，即“電(dian)(dian)(dian)(dian)(dian)(dian)(dian)-熱(re)(re)(re)-電(dian)(dian)(dian)(dian)(dian)(dian)(dian)”轉化。所存儲(chu)的(de)熱(re)(re)(re)能(neng)也可(ke)用于實現(xian)供(gong)熱(re)(re)(re)，即“電(dian)(dian)(dian)(dian)(dian)(dian)(dian)-熱(re)(re)(re)-熱(re)(re)(re)”轉化。電(dian)(dian)(dian)(dian)(dian)(dian)(dian)加熱(re)(re)(re)熔(rong)(rong)(rong)鹽儲(chu)能(neng)啟停方便，能(neng)提高(gao)(gao)現(xian)有儲(chu)熱(re)(re)(re)和發(fa)電(dian)(dian)(dian)(dian)(dian)(dian)(dian)設備的(de)利用率(lv)，降低棄(qi)風(feng)棄(qi)光率(lv)，提升電(dian)(dian)(dian)(dian)(dian)(dian)(dian)站效益(yi)。與(yu)光熱(re)(re)(re)發(fa)電(dian)(dian)(dian)(dian)(dian)(dian)(dian)和電(dian)(dian)(dian)(dian)(dian)(dian)(dian)化學儲(chu)能(neng)相(xiang)比(bi)，電(dian)(dian)(dian)(dian)(dian)(dian)(dian)加熱(re)(re)(re)熔(rong)(rong)(rong)鹽通過在電(dian)(dian)(dian)(dian)(dian)(dian)(dian)廠發(fa)電(dian)(dian)(dian)(dian)(dian)(dian)(dian)機出口(kou)增(zeng)加電(dian)(dian)(dian)(dian)(dian)(dian)(dian)加熱(re)(re)(re)熔(rong)(rong)(rong)鹽裝置就能(neng)實現(xian)，成本下降空間大；與(yu)鋰電(dian)(dian)(dian)(dian)(dian)(dian)(dian)池等(deng)儲(chu)電(dian)(dian)(dian)(dian)(dian)(dian)(dian)池相(xiang)比(bi)，其(qi)優勢為兼(jian)具火電(dian)(dian)(dian)(dian)(dian)(dian)(dian)靈活性改造的(de)功能(neng)，滿(man)足(zu)靈活調峰調頻等(deng)工況需要。

在電(dian)加(jia)(jia)熱(re)(re)(re)(re)熔鹽的使用(yong)情景下，電(dian)能(neng)直接(jie)來源于(yu)發電(dian)機出口，功率規模(mo)大，使用(yong)傳統低(di)(di)壓(ya)(ya)電(dian)阻式(shi)熔鹽加(jia)(jia)熱(re)(re)(re)(re)器(qi)(qi)(qi)不能(neng)滿(man)足需求。因(yin)此，需要采用(yong)高(gao)電(dian)壓(ya)(ya)加(jia)(jia)熱(re)(re)(re)(re)系統如高(gao)電(dian)壓(ya)(ya)電(dian)阻式(shi)、感應式(shi)、電(dian)極式(shi)加(jia)(jia)熱(re)(re)(re)(re)器(qi)(qi)(qi)。高(gao)電(dian)壓(ya)(ya)熔鹽加(jia)(jia)熱(re)(re)(re)(re)器(qi)(qi)(qi)電(dian)壓(ya)(ya)等(deng)級可(ke)達6～10 kV，可(ke)避免(mian)低(di)(di)壓(ya)(ya)電(dian)阻式(shi)加(jia)(jia)熱(re)(re)(re)(re)方案中(zhong)輸(shu)電(dian)線路損耗高(gao)的問題，成(cheng)本(ben)較低(di)(di)。

“電(dian)(dian)(dian)-熱(re)(re)(re)-電(dian)(dian)(dian)”熔(rong)鹽電(dian)(dian)(dian)蓄(xu)熱(re)(re)(re)是(shi)一種電(dian)(dian)(dian)熱(re)(re)(re)儲能(neng)，即“卡諾(nuo)電(dian)(dian)(dian)池”技術。可(ke)采用雙罐熔(rong)鹽系統(tong)，通過冷熱(re)(re)(re)罐循環放(fang)熱(re)(re)(re)發電(dian)(dian)(dian)。“電(dian)(dian)(dian)-熱(re)(re)(re)-熱(re)(re)(re)”轉化的(de)情況(kuang)下，熔(rong)鹽電(dian)(dian)(dian)蓄(xu)熱(re)(re)(re)與固體(ti)蓄(xu)熱(re)(re)(re)具(ju)有(you)相似性，并且(qie)可(ke)以結合。張家(jia)口市崇(chong)禮區城建小(xiao)區使用固體(ti)蓄(xu)熱(re)(re)(re)電(dian)(dian)(dian)鍋爐，綠電(dian)(dian)(dian)進入110 kV電(dian)(dian)(dian)鍋爐加熱(re)(re)(re)鎂(mei)磚至500～550℃，所(suo)儲熱(re)(re)(re)能(neng)再通過換熱(re)(re)(re)器傳導至熱(re)(re)(re)水(shui)，熱(re)(re)(re)水(shui)進入集中供熱(re)(re)(re)系統(tong)。

3.3煙氣蓄熱

大(da)型(xing)火電機(ji)組(zu)中的(de)(de)(de)(de)高(gao)(gao)溫(wen)(wen)煙(yan)(yan)(yan)(yan)(yan)氣(qi)(qi)(qi)(qi)(qi)可(ke)(ke)達700～800℃，若能在熔(rong)(rong)鹽(yan)(yan)(yan)(yan)中蓄(xu)熱(re)形成(cheng)穩(wen)定熱(re)源，就可(ke)(ke)以實(shi)(shi)現(xian)較高(gao)(gao)參(can)數的(de)(de)(de)(de)可(ke)(ke)持續供暖或供生(sheng)活熱(re)水(shui)，同時(shi)也使鍋爐適應熱(re)負荷變(bian)化較大(da)的(de)(de)(de)(de)供熱(re)需要，提高(gao)(gao)機(ji)組(zu)調峰能力。熔(rong)(rong)鹽(yan)(yan)(yan)(yan)煙(yan)(yan)(yan)(yan)(yan)氣(qi)(qi)(qi)(qi)(qi)蓄(xu)熱(re)涉及高(gao)(gao)參(can)數熔(rong)(rong)鹽(yan)(yan)(yan)(yan)以及特(te)殊的(de)(de)(de)(de)煙(yan)(yan)(yan)(yan)(yan)氣(qi)(qi)(qi)(qi)(qi)-熔(rong)(rong)鹽(yan)(yan)(yan)(yan)換(huan)熱(re)器(qi)(qi)。目前，關于高(gao)(gao)溫(wen)(wen)煙(yan)(yan)(yan)(yan)(yan)氣(qi)(qi)(qi)(qi)(qi)與(yu)熔(rong)(rong)鹽(yan)(yan)(yan)(yan)的(de)(de)(de)(de)儲(chu)熱(re)換(huan)熱(re)設(she)備有許(xu)多設(she)計，如引導(dao)煙(yan)(yan)(yan)(yan)(yan)氣(qi)(qi)(qi)(qi)(qi)穿過加(jia)熱(re)棒，實(shi)(shi)現(xian)高(gao)(gao)溫(wen)(wen)煙(yan)(yan)(yan)(yan)(yan)氣(qi)(qi)(qi)(qi)(qi)熔(rong)(rong)鹽(yan)(yan)(yan)(yan)儲(chu)熱(re)的(de)(de)(de)(de)特(te)殊換(huan)熱(re)通(tong)(tong)道(dao)[28]，以及利(li)用高(gao)(gao)溫(wen)(wen)煙(yan)(yan)(yan)(yan)(yan)氣(qi)(qi)(qi)(qi)(qi)加(jia)熱(re)熔(rong)(rong)鹽(yan)(yan)(yan)(yan)的(de)(de)(de)(de)自冷卻屏式加(jia)熱(re)器(qi)(qi)[29]等，其優勢在于傳熱(re)溫(wen)(wen)差大(da)，熱(re)量品(pin)位高(gao)(gao)。煙(yan)(yan)(yan)(yan)(yan)氣(qi)(qi)(qi)(qi)(qi)-熔(rong)(rong)鹽(yan)(yan)(yan)(yan)換(huan)熱(re)器(qi)(qi)還(huan)可(ke)(ke)收(shou)集煉(lian)鋼(gang)過程中產生(sheng)的(de)(de)(de)(de)高(gao)(gao)溫(wen)(wen)余熱(re)，由多根并(bing)聯的(de)(de)(de)(de)金(jin)屬管(guan)組(zu)成(cheng)并(bing)設(she)置(zhi)在煙(yan)(yan)(yan)(yan)(yan)腔內[30]。通(tong)(tong)過煙(yan)(yan)(yan)(yan)(yan)氣(qi)(qi)(qi)(qi)(qi)-熔(rong)(rong)鹽(yan)(yan)(yan)(yan)換(huan)熱(re)器(qi)(qi)收(shou)集煙(yan)(yan)(yan)(yan)(yan)氣(qi)(qi)(qi)(qi)(qi)廢熱(re)，可(ke)(ke)通(tong)(tong)過熔(rong)(rong)鹽(yan)(yan)(yan)(yan)雙(shuang)罐(guan)系統實(shi)(shi)現(xian)再利(li)用。利(li)用雙(shuang)罐(guan)熔(rong)(rong)鹽(yan)(yan)(yan)(yan)中儲(chu)熱(re)實(shi)(shi)現(xian)發電的(de)(de)(de)(de)循(xun)環包括：低溫(wen)(wen)熔(rong)(rong)鹽(yan)(yan)(yan)(yan)從(cong)煙(yan)(yan)(yan)(yan)(yan)氣(qi)(qi)(qi)(qi)(qi)出(chu)口進入換(huan)熱(re)器(qi)(qi)管(guan)束，與(yu)煙(yan)(yan)(yan)(yan)(yan)氣(qi)(qi)(qi)(qi)(qi)換(huan)熱(re)成(cheng)為高(gao)(gao)溫(wen)(wen)熔(rong)(rong)鹽(yan)(yan)(yan)(yan)；依(yi)次經過過熱(re)器(qi)(qi)、蒸(zheng)發器(qi)(qi)、預熱(re)器(qi)(qi)加(jia)熱(re)給水(shui)，輸出(chu)過熱(re)蒸(zheng)汽(qi)驅動汽(qi)輪機(ji)發電，換(huan)熱(re)后的(de)(de)(de)(de)低溫(wen)(wen)熔(rong)(rong)鹽(yan)(yan)(yan)(yan)回(hui)到儲(chu)罐(guan)[31]。現(xian)有的(de)(de)(de)(de)高(gao)(gao)溫(wen)(wen)煙(yan)(yan)(yan)(yan)(yan)氣(qi)(qi)(qi)(qi)(qi)熔(rong)(rong)鹽(yan)(yan)(yan)(yan)換(huan)熱(re)器(qi)(qi)適用溫(wen)(wen)度范圍較小，無法利(li)用低濃度煙(yan)(yan)(yan)(yan)(yan)氣(qi)(qi)(qi)(qi)(qi)的(de)(de)(de)(de)余熱(re)，在安全性和蓄(xu)熱(re)換(huan)熱(re)能力方面依(yi)然有待提高(gao)(gao)。表4為蒸(zheng)汽(qi)、電蓄(xu)熱(re)、煙(yan)(yan)(yan)(yan)(yan)氣(qi)(qi)(qi)(qi)(qi)蓄(xu)熱(re)情景下對熔(rong)(rong)鹽(yan)(yan)(yan)(yan)儲(chu)能技術的(de)(de)(de)(de)選擇(ze)。

4、熔鹽儲能在綠電供熱領域的應用

新(xin)能源發電稱作綠(lv)電，綠(lv)電供(gong)(gong)熱(re)是新(xin)能源消納(na)的(de)一種(zhong)新(xin)途徑，是指使用低(di)(di)谷電或風(feng)、光富(fu)余電量(liang)加(jia)熱(re)熔(rong)鹽(yan)，經過(guo)電-熔(rong)鹽(yan)-給(gei)(gei)水的(de)熱(re)傳遞，用于入(ru)戶(hu)供(gong)(gong)暖。一般通過(guo)雙罐熔(rong)鹽(yan)系統來(lai)實現綠(lv)電供(gong)(gong)熱(re)，其原(yuan)理(li)如(ru)圖4所示[31]。使用綠(lv)電棄電或谷電將熔(rong)鹽(yan)加(jia)熱(re)并儲存在高(gao)溫(wen)(wen)熔(rong)鹽(yan)罐中，白天將高(gao)溫(wen)(wen)熔(rong)鹽(yan)從罐中抽(chou)出，通過(guo)熔(rong)鹽(yan)換熱(re)器加(jia)熱(re)給(gei)(gei)水，滿足多種(zhong)需求。如(ru)供(gong)(gong)給(gei)(gei)90℃熱(re)水實現常規居民(min)供(gong)(gong)熱(re)，供(gong)(gong)給(gei)(gei)180～360℃的(de)中低(di)(di)溫(wen)(wen)工業蒸汽，以及500℃以上的(de)高(gao)溫(wen)(wen)蒸汽。換熱(re)后降溫(wen)(wen)的(de)熔(rong)鹽(yan)再流入(ru)低(di)(di)溫(wen)(wen)熔(rong)鹽(yan)罐，完成(cheng)循環。

綠(lv)電(dian)(dian)(dian)(dian)(dian)(dian)供(gong)(gong)熱(re)(re)(re)(re)是一種高效的(de)清(qing)潔供(gong)(gong)暖(nuan)(nuan)方(fang)式(shi)，在各地已開(kai)展(zhan)試(shi)點工(gong)程(cheng)。河北(bei)辛集熔(rong)鹽蓄(xu)(xu)熱(re)(re)(re)(re)低(di)谷(gu)電(dian)(dian)(dian)(dian)(dian)(dian)綠(lv)色(se)供(gong)(gong)暖(nuan)(nuan)示范工(gong)程(cheng)[32]以低(di)熔(rong)點鹽作為(wei)(wei)(wei)傳熱(re)(re)(re)(re)、蓄(xu)(xu)熱(re)(re)(re)(re)工(gong)質，利用(yong)電(dian)(dian)(dian)(dian)(dian)(dian)網10 h的(de)低(di)谷(gu)電(dian)(dian)(dian)(dian)(dian)(dian)力加熱(re)(re)(re)(re)熔(rong)鹽用(yong)于(yu)供(gong)(gong)給生活熱(re)(re)(re)(re)水(shui)，儲熱(re)(re)(re)(re)時長16 h。北(bei)京(jing)市燃氣熱(re)(re)(re)(re)力供(gong)(gong)熱(re)(re)(re)(re)中(zhong)心[33]將(jiang)夜(ye)間低(di)谷(gu)綠(lv)電(dian)(dian)(dian)(dian)(dian)(dian)轉化(hua)為(wei)(wei)(wei)熱(re)(re)(re)(re)能儲存在180～390℃的(de)熔(rong)鹽中(zhong)，白(bai)天使(shi)用(yong)熔(rong)鹽儲熱(re)(re)(re)(re)為(wei)(wei)(wei)北(bei)京(jing)西站地區供(gong)(gong)暖(nuan)(nuan)，同時對外供(gong)(gong)應(ying)穩定(ding)的(de)中(zhong)低(di)溫(wen)工(gong)業蒸(zheng)汽。與(yu)(yu)燃氣供(gong)(gong)暖(nuan)(nuan)相比，綠(lv)電(dian)(dian)(dian)(dian)(dian)(dian)供(gong)(gong)熱(re)(re)(re)(re)的(de)運行費用(yong)更低(di)；與(yu)(yu)熱(re)(re)(re)(re)泵供(gong)(gong)暖(nuan)(nuan)技術相比，其(qi)初投(tou)資較(jiao)低(di)；與(yu)(yu)水(shui)蓄(xu)(xu)熱(re)(re)(re)(re)式(shi)電(dian)(dian)(dian)(dian)(dian)(dian)采(cai)暖(nuan)(nuan)相比，其(qi)優勢在于(yu)占地面(mian)積小(xiao)，蓄(xu)(xu)能密度高。部(bu)分綠(lv)電(dian)(dian)(dian)(dian)(dian)(dian)供(gong)(gong)熱(re)(re)(re)(re)機組(zu)(zu)能夠同時供(gong)(gong)應(ying)100℃以下的(de)民(min)用(yong)熱(re)(re)(re)(re)水(shui)和各類工(gong)業蒸(zheng)汽，熱(re)(re)(re)(re)效率較(jiao)高，為(wei)(wei)(wei)火電(dian)(dian)(dian)(dian)(dian)(dian)機組(zu)(zu)改造提供(gong)(gong)了新方(fang)向。

綠(lv)電(dian)(dian)(dian)(dian)(dian)(dian)供熱(re)(re)(re)(re)(re)(re)涉及的關(guan)鍵技(ji)(ji)術(shu)為安全穩(wen)定的雙罐(guan)系(xi)統、高(gao)(gao)效(xiao)率的換(huan)熱(re)(re)(re)(re)(re)(re)器(qi)和高(gao)(gao)電(dian)(dian)(dian)(dian)(dian)(dian)壓熔(rong)(rong)(rong)鹽(yan)電(dian)(dian)(dian)(dian)(dian)(dian)加熱(re)(re)(re)(re)(re)(re)器(qi)。普通生活熱(re)(re)(re)(re)(re)(re)水供應系(xi)統中常使用(yong)浮動(dong)盤管型彈(dan)性管束換(huan)熱(re)(re)(re)(re)(re)(re)器(qi)，而(er)在(zai)(zai)熔(rong)(rong)(rong)鹽(yan)-水換(huan)熱(re)(re)(re)(re)(re)(re)的情景下，需要在(zai)(zai)管殼式(shi)(shi)熔(rong)(rong)(rong)鹽(yan)換(huan)熱(re)(re)(re)(re)(re)(re)器(qi)的基礎上進(jin)行改造優化。由于直接(jie)接(jie)入電(dian)(dian)(dian)(dian)(dian)(dian)網的熔(rong)(rong)(rong)鹽(yan)加熱(re)(re)(re)(re)(re)(re)器(qi)可(ke)以節(jie)省變電(dian)(dian)(dian)(dian)(dian)(dian)成(cheng)本，綠(lv)電(dian)(dian)(dian)(dian)(dian)(dian)供熱(re)(re)(re)(re)(re)(re)也(ye)(ye)需要成(cheng)熟可(ke)靠的高(gao)(gao)電(dian)(dian)(dian)(dian)(dian)(dian)壓熔(rong)(rong)(rong)鹽(yan)加熱(re)(re)(re)(re)(re)(re)器(qi)，如各類(lei)高(gao)(gao)壓電(dian)(dian)(dian)(dian)(dian)(dian)阻式(shi)(shi)、電(dian)(dian)(dian)(dian)(dian)(dian)極式(shi)(shi)、電(dian)(dian)(dian)(dian)(dian)(dian)磁感(gan)應式(shi)(shi)加熱(re)(re)(re)(re)(re)(re)器(qi)。對于部分只提供民用(yong)熱(re)(re)(re)(re)(re)(re)水或中低溫工業蒸汽的機組，也(ye)(ye)可(ke)直接(jie)采(cai)用(yong)380 V電(dian)(dian)(dian)(dian)(dian)(dian)極式(shi)(shi)或電(dian)(dian)(dian)(dian)(dian)(dian)阻式(shi)(shi)熔(rong)(rong)(rong)鹽(yan)加熱(re)(re)(re)(re)(re)(re)爐。總(zong)結綠(lv)電(dian)(dian)(dian)(dian)(dian)(dian)供熱(re)(re)(re)(re)(re)(re)不同技(ji)(ji)術(shu)路線(xian)適用(yong)的關(guan)鍵技(ji)(ji)術(shu)見(jian)表(biao)5。

在綠電供熱場景中(zhong)，由熔鹽(yan)加熱蒸汽(qi)或過冷水(shui)，應根據不同的情(qing)況選(xuan)擇低參(can)(can)數或高參(can)(can)數熔鹽(yan)。綠電供熱中(zhong)熔鹽(yan)蒸汽(qi)換熱情(qing)況如圖5所示(shi)。

由(you)圖5a)可見，蒸(zheng)(zheng)(zheng)汽(qi)(qi)的(de)(de)(de)(de)升溫受到夾點(dian)a的(de)(de)(de)(de)限制，若要輸出超(chao)過500℃的(de)(de)(de)(de)高溫工業蒸(zheng)(zheng)(zheng)汽(qi)(qi)，就需要提(ti)高熔(rong)(rong)鹽的(de)(de)(de)(de)蓄(xu)熱溫度至約600℃，選用高參(can)(can)數(shu)熔(rong)(rong)鹽與蒸(zheng)(zheng)(zheng)汽(qi)(qi)進行換熱。在(zai)供(gong)應(ying)中低溫工業蒸(zheng)(zheng)(zheng)汽(qi)(qi)時，使用熔(rong)(rong)點(dian)較低的(de)(de)(de)(de)硝酸鹽熔(rong)(rong)鹽即能滿足需求（圖5b)）。熔(rong)(rong)鹽加熱蒸(zheng)(zheng)(zheng)汽(qi)(qi)的(de)(de)(de)(de)過程(cheng)受夾點(dian)b溫度限制，最終在(zai)低參(can)(can)數(shu)熔(rong)(rong)鹽工作區間150~450℃，可供(gong)應(ying)1.2 MPa、370℃的(de)(de)(de)(de)蒸(zheng)(zheng)(zheng)汽(qi)(qi)。

5、結論

1）目前，熔(rong)鹽(yan)(yan)(yan)儲能(neng)相(xiang)關技(ji)術多(duo)(duo)樣，但各項關鍵技(ji)術都存(cun)在欠缺(que),限制(zhi)了熔(rong)鹽(yan)(yan)(yan)儲能(neng)在新型電(dian)力系統中的應用發展。目前，在多(duo)(duo)元混合熔(rong)鹽(yan)(yan)(yan)領(ling)域(yu)，低熔(rong)點(dian)鹽(yan)(yan)(yan)主要是(shi)鋰、鈣、鉀等元素(su)的硝酸鹽(yan)(yan)(yan)和亞(ya)硝酸鹽(yan)(yan)(yan)體系，如Hitec鹽(yan)(yan)(yan)。耐高溫鹽(yan)(yan)(yan)中氯化鹽(yan)(yan)(yan)的腐蝕性(xing)以及碳酸鹽(yan)(yan)(yan)的易(yi)分(fen)解性(xing)缺(que)陷，還需要展開針對研究(jiu)，為市場提供(gong)更多(duo)(duo)商(shang)業化熔(rong)鹽(yan)(yan)(yan)材料。

另外(wai)，在熔(rong)鹽儲罐的預熱(re)(re)、變工況方面研(yan)究不足(zu)，大型(xing)高(gao)(gao)溫熔(rong)鹽儲罐缺(que)乏完善的制造標準和規范(fan)。市場缺(que)乏成熟的高(gao)(gao)電壓等級熔(rong)鹽電加熱(re)(re)器(qi)(qi)，部分電磁(ci)感應加熱(re)(re)器(qi)(qi)雖可接入高(gao)(gao)電壓，但成本較高(gao)(gao)，并不具備(bei)普遍(bian)實(shi)施性。目前，廣泛采用(yong)的傳統管殼(ke)式換熱(re)(re)器(qi)(qi)，存在未兼顧以熔(rong)鹽為工質的情況，缺(que)少(shao)針(zhen)對(dui)優化熔(rong)鹽換熱(re)(re)器(qi)(qi)的構型(xing)展開的實(shi)驗(yan)研(yan)究。

2）熔(rong)鹽儲(chu)能(neng)系(xi)統的(de)技術(shu)突破能(neng)提高效率、降低成本，也是增強(qiang)光(guang)熱(re)(re)電站競爭力的(de)關鍵(jian)所在(zai)。目前在(zai)光(guang)熱(re)(re)領域，我(wo)國(guo)已具備了支撐光(guang)熱(re)(re)發(fa)電大(da)規模發(fa)展(zhan)的(de)基礎。太陽能(neng)光(guang)熱(re)(re)發(fa)電的(de)成本控制(zhi)主要通過(guo)提高系(xi)統效率和降低設(she)備成本2方面(mian)來實現。

在(zai)提(ti)高系統(tong)效(xiao)率方面主要(yao)(yao)有(you)2種途徑：①高參數(shu)光(guang)熱(re)發電(dian)，使(shi)用(yong)溫度區(qu)間和儲熱(re)容量更大，循環(huan)效(xiao)率更高；②光(guang)熱(re)耦(ou)合(he)新型動力(li)循環(huan)，如熔(rong)鹽(yan)儲能耦(ou)合(he)S-CO2光(guang)熱(re)發電(dian)系統(tong)，需(xu)要(yao)(yao)采用(yong)耐高溫高壓(ya)的(de)印刷電(dian)路(lu)板換熱(re)器(qi)，儲熱(re)系統(tong)溫度需(xu)超過700℃，但目(mu)前還沒有(you)成(cheng)熟的(de)商用(yong)熔(rong)鹽(yan)可以滿足(zu)需(xu)求，存在(zai)技(ji)術瓶(ping)頸(jing)。

降低成本應從熔(rong)鹽(yan)儲(chu)能關(guan)(guan)鍵技術(shu)入手，如關(guan)(guan)于下一代光(guang)熱電(dian)站熔(rong)鹽(yan)的選型，期望(wang)同時滿(man)足低熔(rong)點、耐高溫(wen)、低成本的要(yao)求。但(dan)關(guan)(guan)于不同熔(rong)鹽(yan)、儲(chu)罐、加熱器等的選型還需要(yao)進一步細化(hua)行業標準，形成規范評價體系，促(cu)進技術(shu)配套實現。

3）火電(dian)(dian)機組(zu)與(yu)熔鹽儲能(neng)結合是增(zeng)加機組(zu)靈活性，提高全過程循環效(xiao)率的有效(xiao)方式(shi)。但目前針(zhen)對(dui)火電(dian)(dian)機組(zu)與(yu)熔鹽儲能(neng)耦合的運(yun)行工(gong)況研究(jiu)較少(shao)，雙罐系(xi)統(tong)在其中的安(an)全性保證仍(reng)需(xu)進一(yi)步實(shi)踐研究(jiu)。

現(xian)有(you)熔(rong)(rong)(rong)鹽(yan)-火電耦合發電系(xi)統的(de)(de)研究范圍多針對(dui)主(zhu)(zhu)蒸(zheng)汽(qi)溫度(du)620℃以下的(de)(de)機組(zu)，關于超(chao)超(chao)臨(lin)界機組(zu)主(zhu)(zhu)蒸(zheng)汽(qi)溫度(du)620℃以上的(de)(de)熔(rong)(rong)(rong)鹽(yan)蒸(zheng)汽(qi)蓄熱(re)還缺乏成熟落地的(de)(de)方案。目前，抽(chou)(chou)取再熱(re)或過熱(re)蒸(zheng)汽(qi)加熱(re)熔(rong)(rong)(rong)鹽(yan)的(de)(de)方案可行性已被證(zheng)實，但具體(ti)抽(chou)(chou)汽(qi)量的(de)(de)標準尚不明(ming)確，對(dui)火電系(xi)統整體(ti)的(de)(de)負面影(ying)響(xiang)也需要進一步對(dui)比(bi)研究。

注：本文轉自《熱力發電》期刊，聯合作者為西安熱工研究院有限公司左芳菲，韓偉，姚明宇。轉載此文是出于傳遞更多信息之目的，若有來源標注錯誤或侵犯了您的合法權益，請作者與本網聯系。