“七(qi)法”減小(xiao)煤質化(hua)驗過(guo)程中(zhong)的灰分誤差
實驗室采用快速(su)灰(hui)化法和(he)慢(man)速(su)灰(hui)化法測量煤中(zhong)的灰(hui)分，在此(ci)過(guo)程中(zhong)，樣(yang)品(pin)的稱量準(zhun)確(que)(que)性、入爐灰(hui)化后殘渣(zha)的吸水性、燃燒(shao)溫(wen)度(du)、升溫(wen)速(su)度(du)及溫(wen)度(du)停留時(shi)間的長短、灰(hui)化前爐溫(wen)的校準(zhun)等因(yin)素直接影響(xiang)到煤的灰(hui)分的準(zhun)確(que)(que)度(du)。針對這(zhe)些影響(xiang)因(yin)素，提出(chu)一些減小煤炭灰(hui)分誤差的方法：
(1)對灰皿進(jin)行預燒(shao)(shao)處理。灰分(fen)測試所用灰皿應預先與815±10℃下灼(zhuo)燒(shao)(shao)至質量恒定，再擦干凈(jing)，放入干燥器待用。新灰皿要在900℃條(tiao)件(jian)下進(jin)行不(bu)少(shao)于3次灼(zhuo)燒(shao)(shao)，這是(shi)因為灰皿由(you)化學瓷(ci)高溫(wen)灼(zhuo)燒(shao)(shao)而成，灼(zhuo)燒(shao)(shao)都(dou)會有部(bu)分(fen)物質損失掉(diao)。
(2)加熱初期由常(chang)溫(wen)升至(zhi)500℃的(de)時段，其升溫(wen)時間應(ying)盡量(liang)控制在3-40min。所使(shi)用的(de)應(ying)帶有(you)煙囪(cong)，以利于通氧(yang)及排出分解的(de)SO2，升溫(wen)時應(ying)把(ba)爐門(men)留有(you)15mm左(zuo)右的(de)縫隙(xi)，以確(que)保煤樣灼燒過程(cheng)中(zhong)產(chan)生的(de)氣體及時排出，保證(zheng)煤樣氧(yang)化(hua)*，同時也減少硫(liu)氫化(hua)物和氧(yang)化(hua)物的(de)接觸機會(hui)，從而確(que)保灰(hui)分測(ce)定的(de)準(zhun)確(que)度(du)。爐門(men)的(de)15mm縫隙(xi)對(dui)測(ce)定結果的(de)準(zhun)確(que)度(du)有(you)很大影(ying)響(xiang)。如果升溫(wen)速度(du)偏快，可以把(ba)爐門(men)的(de)縫隙(xi)再(zai)留大些。尺度(du)如何把(ba)握(wo)則需要(yao)針對(dui)不同爐型、不同煤種進行摸索，積(ji)累經(jing)驗。
(3)根據(ju)GB/T212-2008的(de)規(gui)定，應(ying)(ying)稱(cheng)(cheng)(cheng)(cheng)取(qu)(qu)粒度小于0.2mm的(de)空(kong)氣(qi)干(gan)(gan)(gan)燥(zao)(zao)煤(mei)(mei)(mei)樣(yang)(yang)(yang)(yang)(yang)(yang)(yang)(yang)(yang)(yang)，控制其稱(cheng)(cheng)(cheng)(cheng)量(liang)(liang)為(1±0.1)g，并(bing)盡(jin)量(liang)(liang)均勻(yun)攤平(ping)(ping)在(zai)(zai)灰皿(min)(min)底部，使其質量(liang)(liang)不超過(guo)0.15g/cm2。稱(cheng)(cheng)(cheng)(cheng)樣(yang)(yang)(yang)(yang)(yang)(yang)(yang)(yang)(yang)(yang)時應(ying)(ying)按KCQT/GC《電(dian)子(zi)(zi)天(tian)(tian)平(ping)(ping)的(de)使用操作規(gui)程(cheng)》操作電(dian)子(zi)(zi)分(fen)(fen)析天(tian)(tian)平(ping)(ping)。稱(cheng)(cheng)(cheng)(cheng)樣(yang)(yang)(yang)(yang)(yang)(yang)(yang)(yang)(yang)(yang)前檢查天(tian)(tian)平(ping)(ping)是否水平(ping)(ping)，并(bing)校準天(tian)(tian)平(ping)(ping)，檢查天(tian)(tian)平(ping)(ping)內干(gan)(gan)(gan)燥(zao)(zao)劑是否失效及時更(geng)換。稱(cheng)(cheng)(cheng)(cheng)取(qu)(qu)前應(ying)(ying)取(qu)(qu)出(chu)天(tian)(tian)平(ping)(ping)內的(de)干(gan)(gan)(gan)燥(zao)(zao)劑，稱(cheng)(cheng)(cheng)(cheng)灰樣(yang)(yang)(yang)(yang)(yang)(yang)(yang)(yang)(yang)(yang)質量(liang)(liang)時應(ying)(ying)將干(gan)(gan)(gan)燥(zao)(zao)劑放入(ru)天(tian)(tian)平(ping)(ping)內。天(tian)(tian)平(ping)(ping)稱(cheng)(cheng)(cheng)(cheng)量(liang)(liang)過(guo)程(cheng)中(zhong)要(yao)控制環境溫(wen)度的(de)變化，同(tong)一化驗室(shi)的(de)實驗必須使用同(tong)一法碼，灰皿(min)(min)的(de)溫(wen)度與室(shi)溫(wen)相近(jin)，讀(du)數(shu)是要(yao)關閉(bi)兩側的(de)玻璃門，稱(cheng)(cheng)(cheng)(cheng)量(liang)(liang)過(guo)程(cheng)中(zhong)接(jie)觸灰皿(min)(min)的(de)手(shou)指要(yao)保持干(gan)(gan)(gan)燥(zao)(zao)，以減少(shao)稱(cheng)(cheng)(cheng)(cheng)量(liang)(liang)誤差。檢測(ce)煤(mei)(mei)(mei)樣(yang)(yang)(yang)(yang)(yang)(yang)(yang)(yang)(yang)(yang)，確認其粒度小于0.2mm，并(bing)達到空(kong)氣(qi)干(gan)(gan)(gan)燥(zao)(zao)狀(zhuang)態，在(zai)(zai)稱(cheng)(cheng)(cheng)(cheng)取(qu)(qu)樣(yang)(yang)(yang)(yang)(yang)(yang)(yang)(yang)(yang)(yang)品前應(ying)(ying)將瓶(ping)(ping)(ping)中(zhong)的(de)樣(yang)(yang)(yang)(yang)(yang)(yang)(yang)(yang)(yang)(yang)品充分(fen)(fen)攪拌，搖樣(yang)(yang)(yang)(yang)(yang)(yang)(yang)(yang)(yang)(yang)時間不少(shao)于2min。使樣(yang)(yang)(yang)(yang)(yang)(yang)(yang)(yang)(yang)(yang)品盡(jin)量(liang)(liang)混合均勻(yun)然后再稱(cheng)(cheng)(cheng)(cheng)取(qu)(qu)，以保證入(ru)爐樣(yang)(yang)(yang)(yang)(yang)(yang)(yang)(yang)(yang)(yang)品的(de)代表性和*灰化。稱(cheng)(cheng)(cheng)(cheng)樣(yang)(yang)(yang)(yang)(yang)(yang)(yang)(yang)(yang)(yang)時將取(qu)(qu)樣(yang)(yang)(yang)(yang)(yang)(yang)(yang)(yang)(yang)(yang)勺擦干(gan)(gan)(gan)凈，從(cong)(cong)煤(mei)(mei)(mei)樣(yang)(yang)(yang)(yang)(yang)(yang)(yang)(yang)(yang)(yang)瓶(ping)(ping)(ping)中(zhong)不同(tong)部位取(qu)(qu)出(chu)煤(mei)(mei)(mei)樣(yang)(yang)(yang)(yang)(yang)(yang)(yang)(yang)(yang)(yang)放入(ru)灰皿(min)(min)中(zhong)。稱(cheng)(cheng)(cheng)(cheng)取(qu)(qu)1g煤(mei)(mei)(mei)樣(yang)(yang)(yang)(yang)(yang)(yang)(yang)(yang)(yang)(yang)時，至少(shao)分(fen)(fen)3次從(cong)(cong)不同(tong)部位取(qu)(qu)樣(yang)(yang)(yang)(yang)(yang)(yang)(yang)(yang)(yang)(yang)，稱(cheng)(cheng)(cheng)(cheng)取(qu)(qu)0.5g煤(mei)(mei)(mei)樣(yang)(yang)(yang)(yang)(yang)(yang)(yang)(yang)(yang)(yang)時，至少(shao)分(fen)(fen)2次取(qu)(qu)，并(bing)且每次取(qu)(qu)樣(yang)(yang)(yang)(yang)(yang)(yang)(yang)(yang)(yang)(yang)量(liang)(liang)盡(jin)量(liang)(liang)均勻(yun)。稱(cheng)(cheng)(cheng)(cheng)樣(yang)(yang)(yang)(yang)(yang)(yang)(yang)(yang)(yang)(yang)時應(ying)(ying)避免煤(mei)(mei)(mei)樣(yang)(yang)(yang)(yang)(yang)(yang)(yang)(yang)(yang)(yang)灑在(zai)(zai)瓶(ping)(ping)(ping)子(zi)(zi)或灰皿(min)(min)外。從(cong)(cong)煤(mei)(mei)(mei)樣(yang)(yang)(yang)(yang)(yang)(yang)(yang)(yang)(yang)(yang)瓶(ping)(ping)(ping)內取(qu)(qu)出(chu)的(de)多余煤(mei)(mei)(mei)樣(yang)(yang)(yang)(yang)(yang)(yang)(yang)(yang)(yang)(yang)不得放回煤(mei)(mei)(mei)樣(yang)(yang)(yang)(yang)(yang)(yang)(yang)(yang)(yang)(yang)瓶(ping)(ping)(ping)內，稱(cheng)(cheng)(cheng)(cheng)樣(yang)(yang)(yang)(yang)(yang)(yang)(yang)(yang)(yang)(yang)結束立(li)即將煤(mei)(mei)(mei)樣(yang)(yang)(yang)(yang)(yang)(yang)(yang)(yang)(yang)(yang)瓶(ping)(ping)(ping)蓋嚴，以防煤(mei)(mei)(mei)樣(yang)(yang)(yang)(yang)(yang)(yang)(yang)(yang)(yang)(yang)被污(wu)染。
(4)經過(guo)灼燒灰(hui)化后的煤灰(hui)可先在空氣中冷卻(que)5min，之后要(yao)盡快移入(ru)干燥器(qi)中，再冷卻(que)至(zhi)室溫，繼(ji)而進行稱量(liang)。如果遇到陰雨濕潮天氣，可縮短冷卻(que)時間，以免煤灰(hui)吸收過(guo)多的水(shui)分，導致準確度降(jiang)低。
(5)爐(lu)溫(wen)應(ying)(ying)每年定期進(jin)行(xing)一(yi)次專業校準，期間如果更換了工(gong)作熱電偶或加熱件后(hou)則應(ying)(ying)重(zhong)新對爐(lu)溫(wen)進(jin)行(xing)校準。每一(yi)次的校準除了校驗爐(lu)內(nei)工(gong)作溫(wen)度是否符合國家(jia)標準GB/T-2008的要求外，還應(ying)(ying)圈出爐(lu)體內(nei)的恒(heng)溫(wen)區(qu)域，試(shi)樣樣品裝皿入架后(hou)應(ying)(ying)準確(que)置于該恒(heng)溫(wen)區(qu)內(nei)。
(6)建(jian)議(yi)至少每月或每季(ji)用(yong)標(biao)準(zhun)煤(mei)樣標(biao)定一次(ci)儀(yi)器，檢驗馬(ma)弗(fu)爐工(gong)作的穩定性，發現偏(pian)離應分析(xi)和查找原因(yin)，并及時(shi)加以(yi)解決，以(yi)確(que)(que)保測結(jie)果準(zhun)確(que)(que)可(ke)靠。
(7)目前市場上供應的馬弗爐控溫儀多種多樣，有各行業的，有在一定領域通用的等等。鑒于測定煤焦產品的特殊性，務必選擇專業廠家生產的帶煙囪的高溫馬弗爐，并配套升溫程序、溫度控制、時間提示等均符合GB/T212-2008要求的溫度控制系統，購入后應按國標規定條件進行驗收，校準輪內工作溫度，不合要求的產品設備不可投入測試使用。
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