A comparison of fiber and pulp properties of diploid and tetraploid Acacia mangium grown in Vietnam

GRIFFIN A R TWAYI H BRAUNSTEIN R DOWNES G M DO HUU SON HARWOOD C E

SUMMARY:Pulping properties and fibre characteristics of wood from eight-year-old ramets of 6 diploid and 5 tetraploid clones of Acacia mangium grown in Vietnam are reported．Individual clones were represented by two or three ramets．While kraft pulp yield at kappa 20 was very similar for diploid and tetraploids clones，tetraploid clones produced pulp with significantly longer(883 μm)and wider(20．0 μm)fibres，compared to the diploid clones(683 μm and 15．6 μm)．The tetraploid cell wall thickness was greater，resulting in a coarser pulp．Pulmac fibre strengths of the tetraploid were greater than those of the diploid，although their fibre bonding area was lower．The kraft pulp of the best of the tetraploid clones had higher bulk，porosity and tear strength at constant tensile than pulp from a mix of diploid clones and was similar in these traits to softwood pulp．

越南二倍體與四倍體馬占相思樹 (Mangium)的纖維和紙漿性能比較

GRIFFIN A R TWAYI H BRAUNSTEIN R DOWNES G M DO HUU SON HARWOOD C E

摘 要:本文研究了6個(gè)二倍體和5個(gè)四倍體的8年生馬占相思樹 (Mangium)的制漿性能和纖維特性。每個(gè)樹種取樣2個(gè)或3個(gè)。雖然二倍體與四倍體樹種在采用硫酸鹽法蒸煮到卡伯值20時(shí)的制漿得率非常接近，但與二倍體樹種的紙漿纖維尺寸 (長(zhǎng)683 μm，寬15.6 μm)相比，四倍體樹種的紙漿纖維明顯更長(zhǎng) (883 μm)和更寬 (20.0 μm)。四倍體樹種的細(xì)胞壁更厚，因而纖維粗度更大。雖然四倍體樹種的纖維黏合面積較少，但其Pulmac纖維強(qiáng)度要大于二倍體樹種。在同等拉伸強(qiáng)度下，最好的四倍體樹種所得到的硫酸鹽漿比混合的二倍體樹種紙漿具有更好的松

厚度、孔隙率和撕裂強(qiáng)度，就這一特性而言，該紙漿與針葉木漿相似。

Characterization of Oxygen Dispersion in Medium-Consistency Pulp Mixing

HEIKKI MUTIKAINEN KARI PELTONEN TAPIO TIRRIJARI KAYHKo

SUMMARY:A new imaging based method for the measurement of oxygen bubble size was tested in both a laboratory mixer and in a pilot-size medium-consistency mixer．The test method was found to be able to measure oxygen bubble size near the outer surface of the pulp bodies．The smallest observed bubbles were slightly less than 10 μm in diameter．Volumetric cumulative bubble-size distribution was found to be the best way to present the data and illustrate mixing efficiency．In addition the effect of different factors such as rotor speed and pulp consistency on the oxygen bubble size was also studied briefly．In laboratory trials softwood and hardwood pulps behaved very differently．Under conditions where bubbles in softwood pulp were very fine，large size bubbles were found in hardwood pulp．The imaging method was also tested in a pilot-loop and it was found that flow velocity and rotor speed of the Proto-mixer by Andritz had a clear measurable effect on the dispersion．Based on the dispersion characterisation，the optimal rotor speed for the Proto-mixer was 1500 rpm and the optimal flow rate 20 L/s．Results also revealed that some coalescence of bubbles occurred immediately after the mixer，as bubble size increased in the piping before entering the reactor．

中濃紙漿混合時(shí)的氧分散的特點(diǎn)

HEIKKI MUTIKAINEN KARI PELTONEN TAPIO TIRRIJARI KAYHKo

摘 要:本研究對(duì)一種新的基于圖像分析測(cè)量氧氣氣泡尺寸的方法在實(shí)驗(yàn)室攪拌器和中試規(guī)模的中濃混漿機(jī)中進(jìn)行了測(cè)試。研究發(fā)現(xiàn)，該方法能夠測(cè)量與纖維外徑尺寸相當(dāng)?shù)难鯕馀莩叽?。觀察到的最小氣泡直徑略小于10 μm。容積累積氣泡尺寸分布法被證明是顯示數(shù)據(jù)并評(píng)定混合效率的最佳方式。實(shí)驗(yàn)還對(duì)混漿機(jī)轉(zhuǎn)子速度和漿濃對(duì)氧氣氣泡尺寸的影響進(jìn)行了簡(jiǎn)單研究。在實(shí)驗(yàn)室條件下，針葉木漿和闊葉木漿的表現(xiàn)非常不同。同樣條件下氧氣泡在針葉木漿中非常微小，但在闊葉木漿中則很大。在將該方法應(yīng)用于中試混漿回路時(shí)發(fā)現(xiàn):紙漿流速和混漿機(jī) (Andritz公司生產(chǎn)的原型)的轉(zhuǎn)子轉(zhuǎn)速對(duì)氧分散有明顯的影響。根據(jù)對(duì)氧分散的定性分析發(fā)現(xiàn):對(duì)該混漿機(jī)原型機(jī)而言，最佳的轉(zhuǎn)子速度為1500 r/min，最佳紙漿流量為20 L/s。結(jié)果還顯示，離開混漿機(jī)之后氧氣泡馬上發(fā)生聚合，導(dǎo)致氣泡尺寸在進(jìn)入反應(yīng)器之前的管道中變大。

Strategies to reduce heat-induced darkening for enhanced bleachability of mechanical pulps

ANETTE KARLSSON MAGNUS PAULSSON PER ENGSTRAND ERIK HEDENSTRoM

SUMMARY:Under mechanical pulping conditions，elevated temperature initiates reactions in the wood constituents resulting in the formation of coloured structures．In an attempt to reduce the formation of colour，a number of additives have been examined to assess their ability to inhibit heat-induced darkening of a Norway spruce(Picea abies)stone groundwood(SGW)pulp．SGW pulp was used as a model pulp with the purpose of imitating a thermomechanical pulp(TMP)．The heat-treated SGW pulp，both with and without additives present，was subsequently bleached with 4．5%hydrogen peroxide at high pulp consistency and with varying alkali charges in order to examine the hydrogen peroxide bleachability of such pulps．

Heat treatment at 170℃ resulted in a loss of brightness of about 4%ISO after heating for 60 seconds．The reduction in brightness could only partly be regained through high consistency hydrogen peroxide bleaching;the SGW pulp displayed a brightness of 83．7%ISO whereas the heat-treated SGW pulp reached a brightness of 80．4%ISO．

Heat treatment with a low addition rate(1%)of alkaline hydrogen peroxide，sodium bisulphite or sodium sulphite，with a subsequent hydrogen peroxide bleaching stage，resulted in an improved bleached brightness of about 81．6%ISO，i．e．the loss of brightness due to heat was still approximately 2%ISO．Sodium borohydride(1%)did not suppress the thermal darkening but improved the bleached brightness by approximately 2%ISO compared to the heat-treated SGW pulp and resulted in a brightness of 82．6%ISO．Addition of a chelating agent(DTPA，0．11 and 0．45%)and the radical scavengers phthalic hydrazide(1%)and 1-hexanol(1%)suppressed the heat induced darkening somewhat but did not improve the hydrogen peroxide bleachability to any noticeable extent．Addition of citric acid(0．6%)did not suppress the thermal darkening and resulted in impaired bleachability．

抑制熱誘導(dǎo)變黑以增強(qiáng)機(jī)械漿漂白性能的策略

ANETTE KARLSSON MAGNUS PAULSSON PER ENGSTRAND ERIK HEDENSTRoM

摘 要:在機(jī)械制漿條件下，上升的溫度會(huì)啟動(dòng)木材組分間的反應(yīng)，導(dǎo)致有色官能團(tuán)的形成。本實(shí)驗(yàn)檢驗(yàn)了多種添加劑抑制挪威云杉磨木漿熱誘導(dǎo)變黑的能力，以探索減少顏色形成的機(jī)理。磨木漿被用作實(shí)驗(yàn)紙漿來(lái)模擬熱磨機(jī)械漿 (TMP)。沒(méi)有添加助劑的參照漿樣和添加助劑的漿樣經(jīng)過(guò)熱處理，隨后用4.5%過(guò)氧化氫在高漿濃和不同堿用量條件下進(jìn)行了漂白，以檢查這些紙漿的過(guò)氧化氫漂白性能。

實(shí)驗(yàn)發(fā)現(xiàn)，磨木漿在170℃的溫度下熱處理60 s會(huì)導(dǎo)致ISO亮度下降約4%。損失的亮度僅有一部分能通過(guò)高濃度的過(guò)氧化氫漂白得到恢復(fù);未經(jīng)熱處理的磨木漿ISO亮度為83.7%，而經(jīng)熱處理的磨木漿ISO亮度為80.4%。

在熱處理時(shí)添加少量 (1%)堿性過(guò)氧化氫、亞硫酸氫鈉或亞硫酸鈉，隨后進(jìn)行過(guò)氧化氫漂白，能使磨木漿ISO亮度提高到約81.6%;即由熱處理引起的ISO亮度損失仍約2%。與沒(méi)有任何添加劑的熱處理過(guò)的磨木漿相比，添加硼氫化鈉 (1%)沒(méi)有抑制熱誘導(dǎo)變黑，但提高了漂白漿的ISO亮度約2個(gè)百分點(diǎn) (最終ISO亮度為82.6%)。添加螯合劑 (DTPA，0.11%和0.45%)和自由基清除劑鄰苯二甲酸二酰肼 (1%)和1-己醇 (1%)在某種程度上能抑制引起的熱誘導(dǎo)發(fā)黑，但卻沒(méi)有明顯提高過(guò)氧化氫漂白性能。添加檸檬酸 (0.6%)沒(méi)有抑制熱誘導(dǎo)變黑，因此導(dǎo)致漂白性能下降。

Analysis of TRS emissions from recovery boilers

ENZO M E P REYESLEONARDO C de OLIVEIRA DANIEL M SATURNINO ESA VAKKILAINEN MARCELO CARDOSO

SUMMARY:This paper analyses the influence of operating variables on flue gas emissions containing total reduced sulfur(TRS)from a dissolving tank and a recovery boiler．Two pulp mills in Chile provided data to allow this study to be conducted．First，at Lincacel plant，emissions from the dissolving tank vent gas scrubber were studied．Then at the Valdivia plant，the influence of different operating variables on TRS emissions from the recovery boiler were analysed using a multivariate statistical analysis for TRS emissions．In this analysis it was observed that variables affecting the boiler furnace temperature were strongly correlated with changes in the TRS emissions．

回收鍋爐的總還原硫 (TRS)排放量分析

ENZO M E P REYESLEONARDO C de OLIVEIRA DANIEL M SATURNINO ESA VAKKILAINEN MARCELO CARDOSO

摘 要:文章分析了操作參數(shù)對(duì)于從溶解槽和回收鍋爐排放的含有TRS廢氣的影響。智利的兩個(gè)制漿廠對(duì)此研究提供了數(shù)據(jù)。首先，在Lincacel工廠，對(duì)溶解槽尾氣收集器的廢氣進(jìn)行了分析。然后，在Valdivia工廠，使用多元變數(shù)統(tǒng)計(jì)分析方法，對(duì)回收鍋爐的TRS排放因操作參數(shù)的影響進(jìn)行了分析。從這些分析中觀察到，那些影響鍋爐溫度的操作參數(shù)與總還原硫 (TRS)的排放有強(qiáng)烈的相關(guān)性。

Steam，fibre and resin dynamics within a medium density fibreboard(MDF)blowline

KARL MURTON WARREN GRIGSBY ARMIN THUMM

SUMMARY:The effects of blowline steam velocity，resin injection nozzle type and position were determined by injecting fluorescently labelled urea formaldehyde resin into a blowline and examining the resin distribution on the fibre using confocal microscopy．The key results are:

Pressure drop within the blowline is 2．5 times greater with fibre present(normal operation)than for steam only．

Resin coverage increases with greater steam flow through the blowline．

Resin coverage decreased when the resin injection nozzle was shifted from the conventional position after the blowvalve to the end of the blowline．

Resin coverage increases if emulsified wax is mixed with the resin prior to injection．

The blowline steam flow and resin injection position have a greater effect on the resin coverage than the nozzle type for the blowline used．

蒸汽、纖維和樹脂在中密度纖維板 (MDF)噴漿管道中的動(dòng)力學(xué)

KARL MURTON WARREN GRIGSBY ARMIN THUMM

摘 要:通過(guò)注射帶螢光標(biāo)記的尿素樹脂進(jìn)入噴漿管道，從而判斷出蒸汽速度，樹脂噴嘴類型及其位置的影響。同時(shí)使用了共焦顯微鏡檢測(cè)了樹脂在纖維上的分布。主要結(jié)果為:在噴漿管道內(nèi)，有纖維時(shí) (正常操作)的壓力差是只有蒸汽時(shí)的2.5倍;樹脂覆蓋率隨著蒸汽在管道里的流量增加而提升;當(dāng)樹脂噴嘴從原來(lái)位于噴漿閥門后的位置移到噴漿管道末端時(shí)，樹脂覆蓋率減低;若在樹脂注射前將樹脂與乳化蠟混合，樹脂覆蓋率提高;對(duì)此研究中使用的噴漿管道而言，蒸汽流量和樹脂注射位置對(duì)樹脂覆蓋率的影響遠(yuǎn)比樹脂噴嘴類型更為重要。