勝利提質(zhì)褐煤表面含氧基團(tuán)親水位點(diǎn)的微波鈍化
發(fā)布時間：2018-07-31 10:05
【摘要】：國內(nèi)外開發(fā)了許多褐煤脫水提質(zhì)技術(shù),存在的主要問題是脫水提質(zhì)后易回吸水分而浪費(fèi)大量脫水能量,大量文獻(xiàn)報(bào)道干燥褐煤回吸水分的主因是其表面含氧基團(tuán)與水分存在較強(qiáng)相互作用。目前關(guān)于褐煤的研究集中于干燥對其理化性質(zhì)的影響,很少有從本質(zhì)上去研究如何鈍化褐煤表面含氧基團(tuán),從而達(dá)到抑制回吸水分的目的。課題組成員微波干燥褐煤的研究結(jié)果表明微波對褐煤表面含氧基團(tuán)有脫除作用,但針對低價(jià)值褐煤而言,高品質(zhì)微波能量僅用于褐煤脫水不經(jīng)濟(jì),因此在課題組成員研究的基礎(chǔ)上,為了抑制脫水褐煤復(fù)吸水分和能源浪費(fèi),在常規(guī)脫水提質(zhì)的基礎(chǔ)上結(jié)合微波對表面含氧基團(tuán)進(jìn)行鈍化。本文主要研究了勝利褐煤熱空氣、熱真空脫水提質(zhì)過程中微波輻照對含氧基團(tuán)的鈍化作用規(guī)律。通過微觀含氧基團(tuán)含量的變化來體現(xiàn)微波的鈍化作用,并用宏觀的水蒸汽吸附、接觸角及Zeta電位等實(shí)驗(yàn)數(shù)據(jù)來進(jìn)一步證明微波的鈍化作用,從而為脫水提質(zhì)過程中親水含氧基團(tuán)的鈍化和常規(guī)褐煤干燥技術(shù)與微波鈍化結(jié)合奠定理論基礎(chǔ)。褐煤脫水實(shí)驗(yàn)結(jié)果表明,脫水率50%之前,熱真空脫水優(yōu)勢明顯強(qiáng)于熱空氣,微波脫水整個脫水過程都明顯要優(yōu)于前兩者。含氧基團(tuán)研究結(jié)果表明,勝利褐煤中含氧基團(tuán)主要為羥基、羰基、羧基。提質(zhì)褐煤微波輻照后,含氧基團(tuán)含量有所變化,不同脫水程度熱空氣樣品微波輻照后含氧基團(tuán)總量的變化規(guī)律為先增加后減小再增加,不同脫水程度熱真空樣品微波輻照后含氧基團(tuán)總量的變化規(guī)律為先增加后減小再增加再減小。對于熱空氣脫水及熱真空脫水,脫水率達(dá)到50%左右時引入微波能進(jìn)行表面親水含氧基團(tuán)鈍化是較合適的。水蒸汽吸附實(shí)驗(yàn)結(jié)果表明,同一脫水率條件下微波脫水樣品平衡復(fù)吸量遠(yuǎn)小于熱空氣樣品的平衡復(fù)吸量,略小于熱真空樣品的平衡復(fù)吸量,微波脫水樣品的總含水量也小于熱空氣和熱真空樣品的總含水量。脫水樣品微波輻照后其復(fù)吸量的變化趨勢和含氧基團(tuán)變化趨勢基本上一致。微波脫水樣品接觸角與相同脫水程度下的熱空氣和熱真空樣品接觸角相比要遠(yuǎn)大于后兩者的接觸角�？捉Y(jié)構(gòu)特性研究可知微波對褐煤熱空氣干燥煤樣具有擴(kuò)孔作用,微波的擴(kuò)孔作用使得部分微孔向中孔轉(zhuǎn)化,結(jié)合水蒸汽吸附數(shù)據(jù)可知孔結(jié)構(gòu)對褐煤復(fù)吸及其持水能力影響不大。提質(zhì)褐煤微波輻照后Zeta電位絕對值變小。綜合含氧基團(tuán)、水蒸汽吸附、接觸角及Zeta電位的分析可得出:微波能在脫水率達(dá)50%~65%間加入能夠起到較好的鈍化作用。
[Abstract]:Many lignite dehydration and quality technologies have been developed at home and abroad. The main problem is that dehydration is easy to absorb water and waste a lot of dehydration energy. It is reported in a large number of literatures that the main reason for the moisture absorption of dry lignite is the strong interaction between oxygen groups and moisture on the surface of lignite. At present, the research on lignite is focused on the effect of drying on its physical and chemical properties, and few studies have been done on how to passivate oxygen-containing groups on the surface of lignite in order to restrain the absorption of water. The results of microwave drying of lignite show that microwave can remove oxygen-containing groups on lignite surface, but for low-value lignite, it is not economical to use high quality microwave energy only for lignite dehydration. Therefore, in order to restrain the water and energy waste of dehydrated lignite, the surface oxygen-containing groups were passivated on the basis of conventional dehydration and extraction combined with microwave. In this paper, the law of passivation of oxygen containing groups by microwave irradiation in the process of hot air and hot vacuum dehydration of Shengli lignite is studied. The effect of microwave passivation is reflected by the change of the content of oxygen group in microcosmic, and the experimental data of water vapor adsorption, contact angle and Zeta potential are used to further prove the passivation effect of microwave. The results provide a theoretical basis for the passivation of hydrophilic oxygen-containing groups and the combination of conventional lignite drying and microwave passivation. The experimental results show that before the dehydration rate of 50%, the superiority of thermal vacuum dehydration is obviously stronger than that of hot air, and the whole dehydration process of microwave dehydration is obviously better than that of the former two. The results show that the oxygen groups in Shengli lignite are mainly hydroxyl, carbonyl and carboxyl groups. After microwave irradiation of lignite, the content of oxygen-containing groups changed, and the total amount of oxygen groups in hot air samples with different dehydration degree increased first, then decreased, then increased. After microwave irradiation, the total oxygen content of hot vacuum samples with different degree of dehydration is increased first, then decreased and then decreased. For hot air dehydration and thermal vacuum dehydration, when the dehydration rate is about 50%, it is more appropriate to introduce microwave energy to passivate the hydrophilic oxygen-containing groups on the surface. The experimental results of water vapor adsorption show that the equilibrium reabsorption of microwave dehydrated samples is much smaller than that of hot air samples and slightly smaller than that of hot vacuum samples under the same dehydration rate. The total moisture content of microwave dehydrated samples is also smaller than that of hot air and hot vacuum samples. After microwave irradiation, the re-absorption of dehydrated samples is basically the same as that of oxygen-containing groups. The contact angle of microwave dehydrated sample is much larger than that of hot air and thermal vacuum sample under the same dehydration degree. The study of pore structure characteristics shows that microwave has the effect of pore expansion on lignite hot air drying coal sample. The effect of microwave repore expansion makes part of micropore to mesopore transform. Combined with the data of water vapor adsorption, the pore structure has little effect on the absorption of lignite and its water holding capacity. The absolute value of Zeta potential of extracted lignite decreased after microwave irradiation. From the analysis of oxygen group, water vapor adsorption, contact angle and Zeta potential, it is concluded that microwave can play a better role in passivation when the dehydration rate reaches 50% or 65%.
【學(xué)位授予單位】：中國礦業(yè)大學(xué)
【學(xué)位級別】：碩士
【學(xué)位授予年份】：2015
【分類號】：TD849.2
本文編號：2155244
[Abstract]:Many lignite dehydration and quality technologies have been developed at home and abroad. The main problem is that dehydration is easy to absorb water and waste a lot of dehydration energy. It is reported in a large number of literatures that the main reason for the moisture absorption of dry lignite is the strong interaction between oxygen groups and moisture on the surface of lignite. At present, the research on lignite is focused on the effect of drying on its physical and chemical properties, and few studies have been done on how to passivate oxygen-containing groups on the surface of lignite in order to restrain the absorption of water. The results of microwave drying of lignite show that microwave can remove oxygen-containing groups on lignite surface, but for low-value lignite, it is not economical to use high quality microwave energy only for lignite dehydration. Therefore, in order to restrain the water and energy waste of dehydrated lignite, the surface oxygen-containing groups were passivated on the basis of conventional dehydration and extraction combined with microwave. In this paper, the law of passivation of oxygen containing groups by microwave irradiation in the process of hot air and hot vacuum dehydration of Shengli lignite is studied. The effect of microwave passivation is reflected by the change of the content of oxygen group in microcosmic, and the experimental data of water vapor adsorption, contact angle and Zeta potential are used to further prove the passivation effect of microwave. The results provide a theoretical basis for the passivation of hydrophilic oxygen-containing groups and the combination of conventional lignite drying and microwave passivation. The experimental results show that before the dehydration rate of 50%, the superiority of thermal vacuum dehydration is obviously stronger than that of hot air, and the whole dehydration process of microwave dehydration is obviously better than that of the former two. The results show that the oxygen groups in Shengli lignite are mainly hydroxyl, carbonyl and carboxyl groups. After microwave irradiation of lignite, the content of oxygen-containing groups changed, and the total amount of oxygen groups in hot air samples with different dehydration degree increased first, then decreased, then increased. After microwave irradiation, the total oxygen content of hot vacuum samples with different degree of dehydration is increased first, then decreased and then decreased. For hot air dehydration and thermal vacuum dehydration, when the dehydration rate is about 50%, it is more appropriate to introduce microwave energy to passivate the hydrophilic oxygen-containing groups on the surface. The experimental results of water vapor adsorption show that the equilibrium reabsorption of microwave dehydrated samples is much smaller than that of hot air samples and slightly smaller than that of hot vacuum samples under the same dehydration rate. The total moisture content of microwave dehydrated samples is also smaller than that of hot air and hot vacuum samples. After microwave irradiation, the re-absorption of dehydrated samples is basically the same as that of oxygen-containing groups. The contact angle of microwave dehydrated sample is much larger than that of hot air and thermal vacuum sample under the same dehydration degree. The study of pore structure characteristics shows that microwave has the effect of pore expansion on lignite hot air drying coal sample. The effect of microwave repore expansion makes part of micropore to mesopore transform. Combined with the data of water vapor adsorption, the pore structure has little effect on the absorption of lignite and its water holding capacity. The absolute value of Zeta potential of extracted lignite decreased after microwave irradiation. From the analysis of oxygen group, water vapor adsorption, contact angle and Zeta potential, it is concluded that microwave can play a better role in passivation when the dehydration rate reaches 50% or 65%.
【學(xué)位授予單位】：中國礦業(yè)大學(xué)
【學(xué)位級別】：碩士
【學(xué)位授予年份】：2015
【分類號】：TD849.2
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