本文選題：準東煤 + 流化床��； 參考：《中國科學院大學(中國科學院工程熱物理研究所)》2017年碩士論文

【摘要】：目前煤炭仍是我國主要的能源來源,面對日益突出的環(huán)境問題,潔凈煤技術(shù)受到普遍重視,其中流化床氣化技術(shù)因氣化強度大、氣化條件溫和等優(yōu)點受到廣泛關(guān)注,但煤氣化過程中硫、氮污染物的遷移規(guī)律尚不清晰。準東煤儲量大、活性好,是很好的化工、動力用煤,但準東煤中鈉含量高,在燃燒、氣化過程中容易引發(fā)結(jié)渣、積灰、腐蝕等問題,因此研究準東煤氣化過程中鈉、硫、氮的遷移規(guī)律,對于準東煤的開發(fā)應用及緩解我國能源資源緊張、環(huán)境惡化的局面具有重要意義。本文利用熱重-質(zhì)譜聯(lián)用技術(shù)及建立的小型立式爐試驗臺,結(jié)合化學熱力學計算軟件,在接近流化床氣化反應條件下研究了準東煤氣化反應特性;探索了溫度、O2/C等因素對準東煤氣化過程中鈉、硫、氮的遷移特性的影響;構(gòu)建了試驗研究與模擬計算間的關(guān)聯(lián)。利用熱重-質(zhì)譜聯(lián)用技術(shù),對準東煤和神木煤在燃燒及CO2氣化過程中硫、氮氣體的遷移規(guī)律進行了研究。結(jié)果表明:準東煤和神木煤在燃燒過程中釋放的含硫氣體主要為COS和SO2,含氮氣體主要為HCN、NO、NO2和NH3;CO2氣化時硫主要以H2S、COS和SO2的形態(tài)釋放到氣相中,氮幾乎全部以HCN形態(tài)釋放;燃燒和CO2氣化條件下硫、氮的轉(zhuǎn)化機理不同。利用小型立式爐試驗臺考察了準東煤流化床空氣氣化特性。結(jié)果表明:試驗過程中反應器內(nèi)溫度、壓力平穩(wěn),未發(fā)生嚴重結(jié)渣現(xiàn)象;隨氣化溫度升高,煤氣中CO、H2體積百分比增大,煤氣熱值、煤氣產(chǎn)率、碳轉(zhuǎn)化率和冷煤氣效率均增大;隨O2/C增大,煤氣中H2、CO體積百分比減小,CO2和N2體積百分比增大,煤氣熱值減小,碳轉(zhuǎn)化率和煤氣產(chǎn)率均增大,.而冷煤氣效率呈現(xiàn)先增大后減小的趨勢;與神木煤相比,準東煤氣化活性高于神木煤。利用小型立式爐試驗臺進行了準東煤流化床空氣氣化試驗,考察了準東煤氣化過程中鈉、硫、氮的遷移特性。結(jié)果表明:準東煤氣化后的底渣、飛灰顆粒未發(fā)生明顯的熔融粘結(jié);飛灰中鈉主要以NaCl、NaAlSi2O6和NaAlSiCO4的形態(tài)存在,底渣中鈉主要以NaAlSi2O6和NaAlSiO4的形態(tài)存在,高氣化溫度和高O2/C條件下的底渣、飛灰中有更多的NaAlSiO4;鈉的固留率隨氣化溫度升高呈先減小后增大的趨勢,隨O2/C增大呈先略有減小后逐漸增大的趨勢;準東煤原煤及氣化底渣、飛灰中硫大部分以硫酸鹽的形態(tài)存在;氣化過程中有65%～75%的硫以H2S、COS和CS2形式釋放到氣相中;準東煤原煤中氮以季氮、吡咯和吡啶的形態(tài)存在,氣化后底渣、飛灰中氮的形態(tài)發(fā)生了變化。氣化過程中有60%～75%的氮析出至氣相中,其中絕大部分轉(zhuǎn)化為N2,少量氮轉(zhuǎn)化為HCN和NH3;煤氣中HCN含量大于NH3含量,而隨著溫度升高、O2/C增大,氮轉(zhuǎn)化為NH3的比例增大。利用FactSage6.1軟件對準東煤氣化過程進行化學熱力學平衡計算,討論了氣化溫度和O2/C對準東煤中鈉、硫、氮等元素的遷移和轉(zhuǎn)化特性的影響。結(jié)果表明:溫度和O2/C能顯著影響鈉、硫、氮的形態(tài);與試驗研究結(jié)果相結(jié)合可知,增強爐內(nèi)混合、誘導生成高熔點含鈉化合物并避免使用二氧化硅作為床料有助于預防高鈉煤流化床氣化結(jié)渣。
[Abstract]:At present, coal is still the main source of energy in China. In the face of increasingly prominent environmental problems, clean coal technology has been widely paid attention to. The fluidized bed gasification technology has received extensive attention due to the advantages of large gasification intensity and mild gasification conditions. However, the migration law of sulfur and nitrogen pollutants in the process of coal gasification is not clear. It is a good chemical and power coal, but the content of sodium in the coal is high. In the process of combustion and gasification, it is easy to cause the problems of slag, ash accumulation and corrosion. Therefore, it is of great significance to study the development and application of the coal and alleviate the situation of energy resources shortage and environmental deterioration in China. The effects of temperature, O2/C and other factors on the migration characteristics of sodium, sulfur and nitrogen in the process of coal gasification were investigated, and the effects of temperature and O2/C on the migration characteristics of sodium, sulfur and nitrogen in the process of coal gasification were investigated. Using the thermogravimetric - mass spectrometry (TG MS) technique, the transfer of sulfur and nitrogen gas in the combustion and CO2 gasification process is studied by TG mass spectrometry. The results show that the sulfur gases released in the combustion process are mainly COS and SO2, and the nitrogen containing gases are mainly HCN, NO, NO2 and NH3; CO2 is gasified when gasification. Sulfur is released mainly in the form of H2S, COS and SO2 into the gas phase, and almost all nitrogen is released in the form of HCN. The transformation mechanism of sulfur and nitrogen is different under the condition of combustion and CO2 gasification. The characteristics of the air gasification in the fluidized bed are investigated by a small vertical furnace test bench. The results show that the temperature and pressure in the reactor are stable during the test process, and no serious junctions occur. With the increase of gasification temperature, the volume percentage of CO and H2 in gas increases, gas calorific value, gas yield, carbon conversion rate and cold gas efficiency increase. As O2/C increases, H2, CO volume percentage decreases, CO2 and N2 volume percentage increases, gas calorific value decreases, carbon conversion rate and gas yield increase, while cold gas efficiency presents first. Compared with Shenmu coal, the coal gasification activity is higher than Shenmu coal. A small vertical furnace test bed was used to carry out the air gasification test on the coal bed of the coal, and the migration characteristics of sodium, sulfur and nitrogen in the coal gasification process were investigated. The results showed that the fly ash particles did not have obvious melting bond after the coal gasification. The sodium in fly ash is mainly in the form of NaCl, NaAlSi2O6 and NaAlSiCO4. The sodium in the slag mainly exists in the form of NaAlSi2O6 and NaAlSiO4, the high gasification temperature and the bottom slag under the high O2/C condition, there are more NaAlSiO4 in the fly ash. The retention rate of sodium decreases with the increase of gasification temperature and then increases, then decreases with the increase of O2/C. The gradually increasing trend; most of the sulfur in the fly ash is in the form of sulphate; 65% to 75% of the sulfur is released to the gas phase in the form of H2S, COS and CS2 during the gasification process; the nitrogen in the coal raw coal exists in the form of quaternary nitrogen, pyrrole and pyridine, and the formation of nitrogen in the fly ash, and the form of nitrogen in fly ash. In the process, 60% ~ 75% of nitrogen is precipitated into the gas phase, most of which are converted into N2, a small amount of nitrogen is converted to HCN and NH3, and the content of HCN in gas is greater than that of NH3. With the increase of temperature, O2/C increases, and the ratio of nitrogen to NH3 is increased. The chemical thermodynamic equilibrium calculation of the coal gasification process is carried out with FactSage6.1 software, and gasification is discussed. The effects of temperature and O2/C on the transfer and transformation characteristics of sodium, sulfur and nitrogen in the coal are affected. The results show that temperature and O2/C can significantly affect the form of sodium, sulfur and nitrogen. It is known that it is helpful to prevent the high sodium coal from mixing in the furnace, inducing the high melting point sodium compound and avoiding the use of silica as the bed material. Fluidized-bed gasification and slagging.

【學位授予單位】：中國科學院大學(中國科學院工程熱物理研究所)
【學位級別】：碩士
【學位授予年份】：2017
【分類號】：TQ541

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