生(sheng)(sheng)(sheng)(sheng)物(wu)(wu)質(zhi)(zhi)(zhi)能的(de)利用(yong)(yong)技(ji)(ji)(ji)術(shu)主要有生(sheng)(sheng)(sheng)(sheng)物(wu)(wu)質(zhi)(zhi)(zhi)熱裂解(jie)氣化技(ji)(ji)(ji)術(shu)、生(sheng)(sheng)(sheng)(sheng)物(wu)(wu)質(zhi)(zhi)(zhi)熱裂解(jie)液化技(ji)(ji)(ji)術(shu)、沼氣技(ji)(ji)(ji)術(shu)、和生(sheng)(sheng)(sheng)(sheng)物(wu)(wu)質(zhi)(zhi)(zhi)固(gu)(gu)化成(cheng)(cheng)型(xing)(xing)技(ji)(ji)(ji)術(shu)等(deng)(deng)。其中(zhong)，固(gu)(gu)化成(cheng)(cheng)型(xing)(xing)技(ji)(ji)(ji)術(shu)生(sheng)(sheng)(sheng)(sheng)產(chan)(chan)的(de)生(sheng)(sheng)(sheng)(sheng)物(wu)(wu)質(zhi)(zhi)(zhi)燃(ran)料顆粒，可用(yong)(yong)于工(gong)(gong)業燃(ran)料、電(dian)廠發(fa)電(dian)和農村居(ju)民做飯取暖等(deng)(deng)領(ling)域，在瑞典等(deng)(deng)歐洲國家已得到廣泛應用(yong)(yong)。據(ju)統(tong)計，2005年(nian)，世(shi)界生(sheng)(sheng)(sheng)(sheng)物(wu)(wu)質(zhi)(zhi)(zhi)固(gu)(gu)體(ti)成(cheng)(cheng)型(xing)(xing)燃(ran)料的(de)產(chan)(chan)量(liang)已突破420萬噸。我國對(dui)生(sheng)(sheng)(sheng)(sheng)物(wu)(wu)質(zhi)(zhi)(zhi)固(gu)(gu)化成(cheng)(cheng)型(xing)(xing)技(ji)(ji)(ji)術(shu)的(de)研究(jiu)始于20世(shi)紀80年(nian)代(dai)，在生(sheng)(sheng)(sheng)(sheng)物(wu)(wu)質(zhi)(zhi)(zhi)螺(luo)旋擠壓成(cheng)(cheng)型(xing)(xing)、活(huo)塞壓縮成(cheng)(cheng)型(xing)(xing)和制(zhi)(zhi)粒機(ji)擠壓成(cheng)(cheng)型(xing)(xing)等(deng)(deng)方面(mian)都有所(suo)突破。平(ping)模(mo)(mo)制(zhi)(zhi)粒機(ji)加(jia)工(gong)(gong)生(sheng)(sheng)(sheng)(sheng)物(wu)(wu)質(zhi)(zhi)(zhi)顆粒是(shi)固(gu)(gu)化成(cheng)(cheng)型(xing)(xing)技(ji)(ji)(ji)術(shu)的(de)一(yi)種，近幾年(nian)在生(sheng)(sheng)(sheng)(sheng)物(wu)(wu)質(zhi)(zhi)(zhi)制(zhi)(zhi)粒產(chan)(chan)業的(de)發(fa)展過程中(zhong)，平(ping)模(mo)(mo)機(ji)以(yi)其堅固(gu)(gu)耐用(yong)(yong)、原(yuan)料適應性強等(deng)(deng)優點逐漸取得生(sheng)(sheng)(sheng)(sheng)產(chan)(chan)者(zhe)的(de)青(qing)睞，本文將就(jiu)平(ping)模(mo)(mo)制(zhi)(zhi)粒機(ji)加(jia)工(gong)(gong)生(sheng)(sheng)(sheng)(sheng)物(wu)(wu)質(zhi)(zhi)(zhi)顆粒的(de)工(gong)(gong)作原(yuan)理，生(sheng)(sheng)(sheng)(sheng)物(wu)(wu)質(zhi)(zhi)(zhi)原(yuan)料的(de)成(cheng)(cheng)型(xing)(xing)機(ji)理，平(ping)模(mo)(mo)機(ji)加(jia)工(gong)(gong)生(sheng)(sheng)(sheng)(sheng)物(wu)(wu)質(zhi)(zhi)(zhi)顆粒的(de)工(gong)(gong)藝以(yi)及特點等(deng)(deng)方面(mian)進(jin)行介紹(shao)和討(tao)論。
平模制粒機(ji)的工作(zuo)過程(cheng)與顆粒成(cheng)型機(ji)理
Figure 1 Flat die pellet mill
按執行部件的(de)(de)運(yun)動(dong)(dong)狀(zhuang)態分(fen)(fen)，平(ping)模(mo)(mo)制粒(li)(li)機(ji)(ji)有動(dong)(dong)輥(gun)(gun)(gun)式(shi)、動(dong)(dong)模(mo)(mo)式(shi)、模(mo)(mo)輥(gun)(gun)(gun)雙動(dong)(dong)式(shi)三種，后兩種常(chang)見于(yu)小型(xing)(xing)平(ping)模(mo)(mo)制粒(li)(li)機(ji)(ji)，較大機(ji)(ji)型(xing)(xing)一般用動(dong)(dong)輥(gun)(gun)(gun)式(shi)。按磨輥(gun)(gun)(gun)的(de)(de)形狀(zhuang)分(fen)(fen)，又可(ke)以分(fen)(fen)為錐輥(gun)(gun)(gun)式(shi)和(he)直(zhi)輥(gun)(gun)(gun)式(shi)兩種。直(zhi)輥(gun)(gun)(gun)動(dong)(dong)輥(gun)(gun)(gun)式(shi)平(ping)模(mo)(mo)制粒(li)(li)機(ji)(ji)工(gong)作原(yuan)理如(ru)圖1所示：電動(dong)(dong)機(ji)(ji)通過減速箱驅動(dong)(dong)主(zhu)軸，主(zhu)軸帶動(dong)(dong)磨輥(gun)(gun)(gun)，磨輥(gun)(gun)(gun)繞(rao)(rao)主(zhu)軸公(gong)轉的(de)(de)同時(shi)也繞(rao)(rao)磨輥(gun)(gun)(gun)軸自轉。加工(gong)顆粒(li)(li)時(shi)，生物(wu)質原(yuan)料(liao)被送入平(ping)模(mo)(mo)機(ji)(ji)的(de)(de)喂料(liao)室，在(zai)分(fen)(fen)料(liao)器和(he)刮(gua)板的(de)(de)共同作用下均勻地鋪在(zai)平(ping)模(mo)(mo)上，主(zhu)軸帶動(dong)(dong)的(de)(de)壓輥(gun)(gun)(gun)連(lian)續不斷地滾過料(liao)層，將物(wu)料(liao)擠壓進入模(mo)(mo)孔(kong)，物(wu)料(liao)在(zai)模(mo)(mo)孔(kong)中(zhong)經(jing)歷成型(xing)(xing)、保型(xing)(xing)等(deng)過程，一定(ding)時(shi)間后以圓柱(zhu)狀(zhuang)態被擠出(chu)，旋轉的(de)(de)切刀將物(wu)料(liao)切斷，形成顆粒(li)(li)，由掃料(liao)板將顆粒(li)(li)送出(chu)。
Figure 2 The process of pelletization
生(sheng)物(wu)(wu)質(zhi)(zhi)原(yuan)料主要含有(you)纖(xian)(xian)維(wei)素、半纖(xian)(xian)維(wei)素和(he)木質(zhi)(zhi)素等物(wu)(wu)質(zhi)(zhi)，其平模(mo)(mo)機模(mo)(mo)輥間(jian)(jian)的(de)(de)成(cheng)(cheng)(cheng)(cheng)(cheng)型(xing)(xing)機理如下（見圖2）：供料區內的(de)(de)物(wu)(wu)料在(zai)重力(li)作(zuo)用下緊貼在(zai)平模(mo)(mo)上，當壓(ya)(ya)(ya)輥向(xiang)前滾動，物(wu)(wu)料進(jin)入(ru)變形(xing)壓(ya)(ya)(ya)緊區，這時因受到擠壓(ya)(ya)(ya)，原(yuan)料粒(li)子(zi)(zi)不(bu)(bu)斷進(jin)入(ru)粒(li)子(zi)(zi)間(jian)(jian)的(de)(de)空隙(xi)內，間(jian)(jian)隙(xi)中(zhong)的(de)(de)空氣被排出，粒(li)子(zi)(zi)間(jian)(jian)的(de)(de)相互(hu)位置不(bu)(bu)斷更新，粒(li)子(zi)(zi)間(jian)(jian)所有(you)較(jiao)大的(de)(de)空隙(xi)逐漸都被能進(jin)入(ru)的(de)(de)粒(li)子(zi)(zi)占(zhan)據。隨著壓(ya)(ya)(ya)輥繼(ji)續滾動，被壓(ya)(ya)(ya)實的(de)(de)原(yuan)料進(jin)入(ru)擠壓(ya)(ya)(ya)成(cheng)(cheng)(cheng)(cheng)(cheng)型(xing)(xing)區，部分楔形(xing)區、模(mo)(mo)孔(kong)的(de)(de)錐孔(kong)部分和(he)前半部分都屬于(yu)擠壓(ya)(ya)(ya)成(cheng)(cheng)(cheng)(cheng)(cheng)型(xing)(xing)區，該區內，壓(ya)(ya)(ya)力(li)繼(ji)續增(zeng)加(jia)，粒(li)子(zi)(zi)本(ben)身發生(sheng)變形(xing)和(he)塑性流(liu)動，在(zai)垂(chui)直于(yu)最大主應(ying)力(li)的(de)(de)方(fang)向(xiang)被延(yan)展(zhan)，并繼(ji)續充填(tian)周圍(wei)較(jiao)小的(de)(de)空隙(xi)，由于(yu)壓(ya)(ya)(ya)輥和(he)物(wu)(wu)料間(jian)(jian)的(de)(de)摩擦作(zuo)用加(jia)劇而產生(sheng)大量(liang)熱量(liang)，導致原(yuan)料中(zhong)含有(you)的(de)(de)木質(zhi)(zhi)素軟化，粘合力(li)增(zeng)加(jia)，軟化的(de)(de)木質(zhi)(zhi)素和(he)生(sheng)物(wu)(wu)質(zhi)(zhi)中(zhong)固有(you)的(de)(de)纖(xian)(xian)維(wei)素聯合作(zuo)用，使生(sheng)物(wu)(wu)質(zhi)(zhi)逐漸成(cheng)(cheng)(cheng)(cheng)(cheng)形(xing)，這時部分殘(can)余應(ying)力(li)貯存于(yu)成(cheng)(cheng)(cheng)(cheng)(cheng)型(xing)(xing)塊(kuai)內部，粒(li)子(zi)(zi)結合牢固但不(bu)(bu)甚穩定。成(cheng)(cheng)(cheng)(cheng)(cheng)型(xing)(xing)塊(kuai)在(zai)擠壓(ya)(ya)(ya)作(zuo)用下進(jin)入(ru)模(mo)(mo)孔(kong)的(de)(de)保型(xing)(xing)段，在(zai)該段不(bu)(bu)利(li)于(yu)形(xing)狀保持的(de)(de)殘(can)余應(ying)力(li)被消除，顆粒(li)被定型(xing)(xing)。
工藝過(guo)程與試驗
平(ping)模機加(jia)工(gong)生(sheng)物(wu)質(zhi)顆粒基本(ben)工(gong)藝過(guo)程如圖3所示，生(sheng)物(wu)質(zhi)原料(liao)經過(guo)破碎和粉碎后進入干燥環(huan)節。水(shui)分合適的(de)物(wu)料(liao)經混合調質(zhi)后進入平(ping)模機制粒。從制粒機出(chu)來的(de)顆粒經過(guo)冷卻和篩分，得到成品，然后包(bao)裝或(huo)者散裝出(chu)廠。
Figure 3 the manufacturing processes of biomass fuel pellets
生(sheng)物(wu)質制粒的基本工(gong)藝步驟大體類(lei)似，然而(er)由(you)于原料的物(wu)性不同、成(cheng)型機的工(gong)作原理不同，具體的工(gong)藝過(guo)程還是有所(suo)區別，對平(ping)模機制粒的關鍵工(gong)藝步驟具體介紹如下(xia)：
粉碎(sui)環(huan)節(jie),平(ping)(ping)(ping)模(mo)機制(zhi)粒時，原料粒徑(jing)越(yue)小，粒子之間越(yue)容(rong)易互(hu)相充填、嵌(qian)合(he)，因(yin)此制(zhi)粒機的(de)單位(wei)產量平(ping)(ping)(ping)均能耗就越(yue)小，平(ping)(ping)(ping)模(mo)和壓輥等(deng)易損件的(de)磨(mo)損速度也較(jiao)慢，制(zhi)成顆(ke)粒的(de)抗滲水性(xing)和硬(ying)度等(deng)指標(biao)也越(yue)高，然而(er)一(yi)(yi)(yi)味(wei)追求粒徑(jing)的(de)減小會使粉碎(sui)環(huan)節(jie)的(de)能耗驟升，因(yin)此應當(dang)在滿(man)足平(ping)(ping)(ping)模(mo)制(zhi)粒機加工要求的(de)前(qian)提(ti)下(xia)，使粒徑(jing)盡量大(da)些。事實上，能夠壓制(zhi)大(da)粒徑(jing)的(de)原料是平(ping)(ping)(ping)模(mo)機的(de)優勢(shi)之一(yi)(yi)(yi)，一(yi)(yi)(yi)般對作物秸稈等(deng)原料，其最大(da)顆(ke)粒外形尺寸要求小于2×2×30mm，而(er)對于木質原料，則要求更嚴格一(yi)(yi)(yi)些。
干(gan)燥(zao)(zao)環(huan)節,干(gan)燥(zao)(zao)的(de)(de)(de)主要(yao)目的(de)(de)(de)是調(diao)節原(yuan)(yuan)料(liao)(liao)的(de)(de)(de)含(han)水(shui)(shui)率，使其(qi)穩定(ding)均一(yi)(yi)(yi)，適(shi)合(he)(he)制粒(li)(li)機加工(gong)(gong)，在(zai)制粒(li)(li)成(cheng)型過(guo)程(cheng)中(zhong)，合(he)(he)適(shi)的(de)(de)(de)水(shui)(shui)分(fen)一(yi)(yi)(yi)方面(mian)能(neng)(neng)(neng)(neng)夠傳遞壓(ya)輥(gun)的(de)(de)(de)壓(ya)力，另一(yi)(yi)(yi)方面(mian)能(neng)(neng)(neng)(neng)起(qi)到潤滑劑的(de)(de)(de)作用(yong)，輔助(zhu)粒(li)(li)子(zi)互相(xiang)填充，從而促進(jin)原(yuan)(yuan)料(liao)(liao)成(cheng)型。但是含(han)水(shui)(shui)率過(guo)大時(shi)(shi)，水(shui)(shui)分(fen)容易在(zai)顆粒(li)(li)之(zhi)間(jian)形成(cheng)隔離層，使得層間(jian)無(wu)法緊密結合(he)(he)，擠出的(de)(de)(de)顆粒(li)(li)容易膨脹散開，不(bu)能(neng)(neng)(neng)(neng)成(cheng)型，因此控制合(he)(he)適(shi)的(de)(de)(de)原(yuan)(yuan)料(liao)(liao)含(han)水(shui)(shui)率在(zai)加工(gong)(gong)過(guo)程(cheng)中(zhong)尤(you)為(wei)重要(yao)。一(yi)(yi)(yi)般(ban)從自然(ran)界(jie)中(zhong)收集的(de)(de)(de)生物質(zhi)原(yuan)(yuan)料(liao)(liao)含(han)水(shui)(shui)率大部分(fen)分(fen)布在(zai)20-40%之(zhi)間(jian)，高(gao)的(de)(de)(de)能(neng)(neng)(neng)(neng)達到55%，平(ping)模制粒(li)(li)機加工(gong)(gong)生物質(zhi)原(yuan)(yuan)料(liao)(liao)時(shi)(shi)，要(yao)求原(yuan)(yuan)料(liao)(liao)的(de)(de)(de)水(shui)(shui)分(fen)在(zai)10-14%之(zhi)間(jian)，當加工(gong)(gong)玉米秸稈一(yi)(yi)(yi)類含(han)糖較(jiao)(jiao)多的(de)(de)(de)原(yuan)(yuan)料(liao)(liao)時(shi)(shi)含(han)水(shui)(shui)量可允許稍高(gao)。常規(gui)的(de)(de)(de)干(gan)燥(zao)(zao)工(gong)(gong)藝一(yi)(yi)(yi)般(ban)用(yong)帶式干(gan)燥(zao)(zao)器(qi)(qi)、滾筒干(gan)燥(zao)(zao)器(qi)(qi)、廂式干(gan)燥(zao)(zao)器(qi)(qi)等設(she)備(bei)進(jin)行，然(ran)而不(bu)得不(bu)承認這(zhe)一(yi)(yi)(yi)環(huan)節會耗費掉可觀的(de)(de)(de)能(neng)(neng)(neng)(neng)量。筆者(zhe)認為(wei)，如今(jin)太(tai)(tai)陽能(neng)(neng)(neng)(neng)干(gan)燥(zao)(zao)技術(shu)已較(jiao)(jiao)為(wei)成(cheng)熟，完全可以(yi)用(yong)太(tai)(tai)陽能(neng)(neng)(neng)(neng)溫(wen)室配(pei)備(bei)以(yi)翻拋(pao)設(she)備(bei)對生物質(zhi)原(yuan)(yuan)料(liao)(liao)進(jin)行除濕，一(yi)(yi)(yi)般(ban)生物質(zhi)原(yuan)(yuan)料(liao)(liao)的(de)(de)(de)干(gan)燥(zao)(zao)，要(yao)求溫(wen)度水(shui)(shui)平(ping)較(jiao)(jiao)低(di)(di)，大約在(zai)40－70℃之(zhi)間(jian)，這(zhe)正好與(yu)太(tai)(tai)陽能(neng)(neng)(neng)(neng)利(li)用(yong)領域(yu)中(zhong)的(de)(de)(de)低(di)(di)溫(wen)利(li)用(yong)相(xiang)適(shi)應(ying)，與(yu)傳統干(gan)燥(zao)(zao)工(gong)(gong)藝相(xiang)比，可以(yi)大量節省常規(gui)能(neng)(neng)(neng)(neng)源(yuan)，降低(di)(di)固定(ding)投資，經濟效益(yi)顯著。
制(zhi)(zhi)粒(li)環節(jie)(jie)，干(gan)燥好的(de)物料進(jin)入制(zhi)(zhi)粒(li)環節(jie)(jie)，可(ke)(ke)(ke)以(yi)不用調(diao)質處理，直接加工。有條(tiao)件的(de)生產廠家可(ke)(ke)(ke)選配自(zi)動(dong)(dong)(dong)控制(zhi)(zhi)系統和(he)(he)模輥(gun)自(zi)動(dong)(dong)(dong)調(diao)隙(xi)裝(zhuang)置。自(zi)動(dong)(dong)(dong)控制(zhi)(zhi)系統根據主機(ji)(ji)(ji)電(dian)流的(de)變(bian)化(hua)調(diao)節(jie)(jie)喂(wei)料電(dian)機(ji)(ji)(ji)的(de)變(bian)頻器，從而實(shi)時調(diao)節(jie)(jie)喂(wei)料量(liang)，這能有效的(de)避免堵機(ji)(ji)(ji)現象的(de)發生。模輥(gun)自(zi)動(dong)(dong)(dong)調(diao)隙(xi)裝(zhuang)置能采集(ji)模輥(gun)間(jian)(jian)(jian)(jian)隙(xi)數(shu)據，通(tong)過反饋、對比來控制(zhi)(zhi)液壓(ya)(ya)(ya)系統，使間(jian)(jian)(jian)(jian)隙(xi)與設定值(zhi)相一(yi)(yi)致，并能在生產過程中隨(sui)時變(bian)化(hua)。一(yi)(yi)般(ban)而言，啟(qi)動(dong)(dong)(dong)階(jie)段，磨輥(gun)間(jian)(jian)(jian)(jian)隙(xi)應當(dang)盡量(liang)小(xiao)些，這可(ke)(ke)(ke)以(yi)減(jian)小(xiao)啟(qi)動(dong)(dong)(dong)力矩，降(jiang)低電(dian)機(ji)(ji)(ji)負荷。進(jin)入穩態工作(zuo)(zuo)后，磨輥(gun)間(jian)(jian)(jian)(jian)隙(xi)應當(dang)稍(shao)大(da)，這可(ke)(ke)(ke)以(yi)增大(da)壓(ya)(ya)(ya)縮(suo)行程，得(de)到堅硬(ying)光(guang)滑的(de)顆粒(li)。可(ke)(ke)(ke)以(yi)將間(jian)(jian)(jian)(jian)隙(xi)隨(sui)時間(jian)(jian)(jian)(jian)變(bian)化(hua)的(de)設置輸入控制(zhi)(zhi)系統，啟(qi)動(dong)(dong)(dong)后，機(ji)(ji)(ji)器可(ke)(ke)(ke)以(yi)自(zi)動(dong)(dong)(dong)調(diao)節(jie)(jie)模輥(gun)間(jian)(jian)(jian)(jian)隙(xi)。壓(ya)(ya)(ya)輥(gun)和(he)(he)平(ping)模都是易(yi)磨損件，需(xu)要定期更換，壓(ya)(ya)(ya)輥(gun)的(de)服役(yi)期可(ke)(ke)(ke)以(yi)稍(shao)長(chang)一(yi)(yi)點，但最(zui)好能夠和(he)(he)平(ping)模一(yi)(yi)起(qi)更換。一(yi)(yi)般(ban)，平(ping)模可(ke)(ke)(ke)以(yi)工作(zuo)(zuo)800-2000小(xiao)時不等，這要視零件的(de)材質和(he)(he)加工工藝而定。 (責任(ren)編輯：wzxny)
