-
摘要: 基于水平管式反应器气化条件，结合化学吸收-分光光度法和X射线光电子能谱（XPS）分析，研究了四种富氮生物质（豆秆（SBS）、稻秆（RS）、玉米秆（CS）和中密度纤维板（MDF））气化过程NOx前驱物生成特性及规律，对比考察了燃料特性（燃料N官能团、N含量）及气化条件（温度、气化介质）的影响。结果表明，NH3-N为主要NOx前驱物并伴随一定量的HCN-N，绝大部分形成于初次裂解和二次反应同时进行的挥发分析出阶段。各因素通过影响NOx前驱物组分生成路径而改变其产率：燃料特性对产率的影响主要体现在N官能团（胺类-N（N-A）类型）稳定性方面，与N含量关系不大，因不稳定N-A在初次裂解中的关键作用，MDF总产率高达74.7%（质量分数），比秸秆类平均总产率高出15%（质量分数）；温度和气化介质会影响二次反应中与NOx前驱物相关的反应路径（特别是加氢氢化反应），秸秆SBS气化，温度从800℃到1000℃，NH3-N产率从38.9%（质量分数）增加至47.7%（质量分数），HCN-N产率先增加后减少，峰值为18.3%（质量分数），源于各反应路径受温度影响的平衡性；气化介质改变加氢氢化反应，CO2主要影响HCN-N，起一定抑制作用，H2O主要影响NH3-N，起促进作用，因此，通过调节气化介质比例可一定程度改变NOx前期物组分的选择性。Abstract: Based on gasification of 4 N-rich biomass (SBS, RS, CS and MDF) in a horizontal tubular quartz reactor, formation characteristics of NOx precursors were investigated with the help of chemical absorption-spectrophotometry and XPS methods. Effects of fuel's properties (nitrogen functionality and nitrogen content) and gasification conditions (temperature and gasifying agent) were discussed and compared. The results indicate that NH3-N is the predominant NOx precursor species mainly produced during devolatilization stage. Each operational factor would alter the yield of each NOx precursor by affecting their formation pathways. On one hand, thermal stability of nitrogen functionality in fuels (N-A) is a much more important factor than nitrogen content among fuel's properties. Subsequently, due to the primary cracking of unstable N-A (polyamide), total yield of NOx precursors for MDF reaches up to 74.7% which is higher than that for other straw biomass by 15%. On the other hand, gasification conditions would influence the reaction routes relevant to NOx precursors during secondary reactions, especially for the hydrogenation reaction. As a consequence, during SBS gasification, when temperature rises from 800 to 1000℃, NH3-N yield keeps a constant increase from 38.9% to 47.7% while HCN-N increases first and then decreases with a peak value of 18.3%, which may depend on the balance between reaction routes affected by temperature. As for gasifying agent, the presence of CO2 would partly inhibit HCN-N yield while the introduction of H2O would moderately promote NH3-N yield, which is attributed that the hydrogenation reaction would be strongly affected by gasifying agent. Hence, it is concluded that the selectivity and partitioning of NOx precursors could be changed by employing different ratio of gasifying agents.
-
Key words:
- N-rich biomass gasification /
- NOx precursors /
- NH3-N /
- gasifying agent /
- hydrogenation reaction
-
图 2 SBS在950 ℃下CO2气化各前驱物组分产率、总产率及比值随CO2流量的变化
Figure 2 Changes of NOx precursors vs. gas flow during SBS gasification with CO2 at 950 ℃
(a): NH3-N and HCN-N yield; (b): total yield; (c): ratio of HCN-N/NH3-N
图 3 SBS在950 ℃下H2O或H2O+CO2气化各前驱物组分产率、总产率及比值随水蒸气浓度的变化
Figure 3 Changes of NOx precursors vs. steam flow during SBS gasification with H2O or H2O/CO2 at 950 ℃
NH3-N; HCN-N(a): NH3-N and HCN-N yield; (b): total yield; (c): ratio of HCN-N/NH3-N
图 4 SBS在CO2气氛下气化各前驱物组分产率、总产率及比值随气化温度的变化
Figure 4 Changes of NOx precursors vs. temperature during SBS gasification with CO2
(a): NH3-N and HCN-N yield; (b): total yield; (c): ratio of HCN-N/NH3-N
图 5 生物质样品燃料N官能团特征
Figure 5 Characteristics of nitrogen functionalities in raw biomass samples
(a): SBS; (b): RS; (c): CS; (d): MDF
图 6 不同生物质原料在950 ℃下CO2气化各前驱物组分产率、总产率及比值对比
Figure 6 Comparisons of NOx precursors during different biomass gasification with CO2 at 950 ℃
(a): NH3-N and HCN-N yield; (b): total yield; (c): ratio of HCN-N/NH3-N
图 7 不同转化率的生物质CO2气化各前驱物组分产率及N分布
Figure 7 Yields of NOx precursors and nitrogen distribution under different conversion yield of biomass gasification with CO2 at 950 ℃
(a), (c): NH3-N or HCN yield-SBS, MDF; (b), (d): nitrogen distribution-SBS, MDF ●: NH3-N; ▲: HCN-N; char-N; NOx precursors-N; other-N
图 8 不同转化率下SBS和MDF气化半焦的N 1s谱图
Figure 8 N 1s XPS spectra of chars generated at different conversion yield of biomass gasification with CO2 at 950 ℃
图 9 不同转化率下SBS和MDF气化半焦中各N官能团含量
Figure 9 Yield of each nitrogen functionality in char vs. conversion yield during biomass gasification with CO2 at 950 ℃
(a): SBS; (b): MDF
图 10 生物质气化燃料N到NOx前驱物迁移路径示意图
Figure 10 Evolution of fuel-N to NOx precursors during biomass gasification with CO2/H2O
表 1 样品的元素分析和工业分析
Table 1 Ultimate and proximate analyses of biomass samples
Sample Ultimate analysis wdaf/% Proximate analysis wdb/% C H N S O* V FC A SBS 46.43 6.49 1.33 0.05 45.70 77.77 16.91 5.32 RS 46.54 6.43 1.49 0.14 45.40 71.82 13.37 14.81 CS 47.31 6.38 3.09 0.13 43.09 66.39 15.77 17.84 MDF 48.63 6.18 4.17 0.00 41.02 82.24 15.11 2.65 *: calculated by difference 
下载: 导出CSV
表 2 实验操作条件
Table 2 Operational factors chosen for the experiments
Factors Unit Value range Nitrogen content w/% 1.33 (SBS), 1.49 (RS), 3.09 (CS), 4.17 (MDF) Atmosphere CO2, Ar /(mL·min-1) 300, 400, 500, 600 H2O /(mg·min-1) 30, 60, 90 Temperature t /℃ 800, 850, 900, 950, 1000 Conversion yield w /% 60, 75, 80, 85, 95
下载: 导出CSV
-
[1] MCKENDRY P. Energy production from biomass (part 3):Gasification technologies[J]. Bioresource Technol, 2002, 83(1):55-63. doi: 10.1016/S0960-8524(01)00120-1 [2] 高翔.江苏省农作物秸秆综合利用技术分析[J].江西农业学报, 2010, (12):130-133, 140. doi: 10.3969/j.issn.1001-8581.2010.12.040GAO Xiang. Analysis on comprehensive utilization technique of crop straw in Jiangsu province[J]. Acta Agric Jiangxi, 2010, (12):130-133, 140. doi: 10.3969/j.issn.1001-8581.2010.12.040 [3] LV X, XIAO J, SHEN L, ZHOU Y. Experimental study on the optimization of parameters during biomass pyrolysis and char gasification for hydrogen-rich gas[J]. Int J Hydrog Energy, 2016, 41(47):21913-21925. doi: 10.1016/j.ijhydene.2016.09.200 [4] TCHOFFOR P A, MORADIAN F, PETTERSSON A, DAVIDSSON K O, THUNMAN H. Influence of fuel ash characteristics on the release of potassium, chlorine, and sulfur from biomass fuels under steam-fluidized bed gasification conditions[J]. Energy Fuels, 2016, 30(12):10435-10442. doi: 10.1021/acs.energyfuels.6b01470 [5] 费华, 李培生, 孙金丛, 张莹, 罗凯, 张红婴.修正离散随机孔模型应用于两种秸秆生物质焦CO2气化的动力学研究[J].中国电机工程学报, 2016, 36(9):2459-2464. http://kns.cnki.net/KCMS/detail/detail.aspx?filename=zgdc201609018&dbname=CJFD&dbcode=CJFQFEI Hua, LI Pei-sheng, SUN Jin-cong, ZHANG Ying, LUO Kai, ZHANG Hong-ying. Kinetics of two straw biomass chars gasification with CO2 based a modified discrete random pore model[J]. Proc CSEE, 2016, 36(9):2459-2464. http://kns.cnki.net/KCMS/detail/detail.aspx?filename=zgdc201609018&dbname=CJFD&dbcode=CJFQ [6] WEI J, GONG Y, GUO Q, DING L, WANG F, YU G. Physicochemical evolution during rice straw and coal co-pyrolysis and its effect on co-gasification reactivity[J]. Bioresour Technol, 2017, 227:345-352. doi: 10.1016/j.biortech.2016.12.068 [7] ALI D A, GADALLA M A, ABDELAZIZ O Y, HULTEBERG C P, ASHOUR F H. Co-gasification of coal and biomass wastes in an entrained flow gasifier:Modelling, simulation and integration opportunities[J]. J Nat Gas Sci Eng, 2017, 37:126-137. doi: 10.1016/j.jngse.2016.11.044 [8] ZHOU J C, MASUTANI S M, ISHIMURA D M, TURN S Q, KINOSHITA C M. Release of fuel-bound nitrogen during biomass gasification[J]. Ind Eng Chem Res, 2000, 39(3):626-634. doi: 10.1021/ie980318o [9] WILK V, HOFBAUER H. Conversion of fuel nitrogen in a dual fluidized bed steam gasifier[J]. Fuel, 2013, 106:793-801. doi: 10.1016/j.fuel.2012.12.056 [10] AZNAR M, ANSELMO M S, MANYA J J, MURILLO M B. Experimental study examining the evolution of nitrogen compounds during the gasification of dried sewage sludge[J]. Energy Fuels, 2009, 23:3236-3245. doi: 10.1021/ef801108s [11] CAO J J, SHEN Z X, CHOW J C, WATSON J G, LEE S C, TIE X X, HO K F, WANG G H, HAN Y M. Winter and summer PM2.5 chemical compositions in fourteen chinese cities[J].J Air Waste Manage, 2012, 62(10):1214-1226. doi: 10.1080/10962247.2012.701193 [12] TIAN F J, YU J L, MCKENZIE L J, HAYASHI J I, CHIBA T, LI C Z. Formation of NOx precursors during the pyrolysis of coal and biomass. Part VⅡ. Pyrolysis and gasification of cane trash with steam[J]. Fuel, 2005, 84(4):371-376. doi: 10.1016/j.fuel.2004.09.018 [13] PATERSON N, ZHUO Y, DUGWELL D, KANDIYOTI R. Formation of hydrogen cyanide and ammonia during the gasification of sewage sludge and bituminous coal[J]. Energy Fuels, 2005, 19(3):1016-1022. doi: 10.1021/ef049688h [14] LIU H, GIBBS B M. Modeling NH3 and HCN emissions from biomass circulating fluidized bed gasifiers[J]. Fuel, 2003, 82(13):1591-1604. doi: 10.1016/S0016-2361(03)00091-7 [15] ALJBOUR S H, KAWAMOTO K. Bench-scale gasification of cedar wood-Part Ⅱ:Effect of operational conditions on contaminant release[J]. Chemosphere, 2013, 90(4):1501-1507. doi: 10.1016/j.chemosphere.2012.08.030 [16] BROER K M, BROWN R C. Effect of equivalence ratio on partitioning of nitrogen during biomass gasification[J]. Energy Fuels, 2016, 30(1):407-413. doi: 10.1021/acs.energyfuels.5b02197 [17] REN Q, ZHAO C, WU X, LIANG C, CHEN X, SHEN J, WANG Z. Formation of NOx precursors during wheat straw pyrolysis and gasification with O2 and CO2[J]. Fuel, 2010, 89(5):1064-1069. doi: 10.1016/j.fuel.2009.12.001 [18] TIAN F J, YU J L, MCKENZIE L J, HAYASHI J, LI C Z. Conversion of fuel-N into HCN and NH3 during the pyrolysis and gasification in steam:A comparative study of coal and biomass[J]. Energy Fuels, 2007, 21(2):517-521. doi: 10.1021/ef060415r [19] REN Q Q, ZHAO C S. NOx and N2O precursors from biomass pyrolysis:Nitrogen transformation from amino acid[J]. Environ Sci Technol, 2012, 46(7):4236-4240. doi: 10.1021/es204142e [20] STUBENBERGER G, SCHARLER R, ZAHIROVIC S, OBERNBERGER I. Experimental investigation of nitrogen species release from different solid biomass fuels as a basis for release models[J]. Fuel, 2008, 87(6):793-806. doi: 10.1016/j.fuel.2007.05.034 [21] 陈树人, 蒋成宠, 姚勇, 蒋晓霞.水稻秸秆压块热值模型构建及其影响因子相关性分析[J].农业工程学报, 2014, 30(24):200-208. doi: 10.3969/j.issn.1002-6819.2014.24.024CHEN Shu-ren, JIANG Cheng-chong, YAO Yong, JIANG Xiao-xia. Establishment of predicted model of calorific value for rice strawbriquetting and analysis of correlation of its influencing factors[J]. Trans Chin Soc Agric Eng, 2014, 30(24):200-208. doi: 10.3969/j.issn.1002-6819.2014.24.024 [22] 张发安, 张建辉.中密度纤维板企业环保措施[J].林产工业, 2012, 39(2):35-37, 40. http://www.cqvip.com/QK/90275X/201202/41550003.htmlZHANG Fa-an, ZHANG Jian-hui. Environmental protection measures to be used in MDF enterprises[J]. Chin Forest Prod Ind, 2012, 39(2):35-37, 40. http://www.cqvip.com/QK/90275X/201202/41550003.html [23] 张晓鸿, 詹昊, 阴秀丽, 吴创之.富氮生物质原料热解过程中NOx前驱物释放特性研究[J].燃料化学学报, 2016, 44(12):1464-1472. doi: 10.3969/j.issn.0253-2409.2016.12.008ZHANG Xiao-hong, ZHAN Hao, YIN Xiu-li, WU Chuang-zhi. Release characteristic of NOx precursors during the pyrolysis of nitrogen-rich biomass[J]. J Fuel Chem Technol, 2016, 44(12):1464-1472. doi: 10.3969/j.issn.0253-2409.2016.12.008 [24] ZHAN H, YIN X L, HUANG Y Q, ZHANG X H, YUAN H Y, XIE J J, WU C Z. Characteristics of NOx precursors and their formation mechanism during pyrolysis of herb residues[J].J Fuel Chem Technol, 2017, 45(3):279-288. doi: 10.1016/S1872-5813(17)30017-8 [25] VALENTIM B, GUEDES A, BOAVIDA D. Nitrogen functionality in "oil window" rank range vitrinite rich coals and chars[J]. Org Geochem, 2012, 42(5):502-509. http://www.academia.edu/8338434/Nitrogen_functionality_in_oil_window_rank_range_vitrinite_rich_coals_and_chars [26] WEI L H, WEN L, YANG T H, ZHANG N. Nitrogen transformation during sewage sludge pyrolysis[J]. Energy Fuels, 2015, 29(8):5088-5094. doi: 10.1021/acs.energyfuels.5b00792 [27] ZHAN H, YIN X L, HUANG Y Q, YUAN H Y, WU C Z. NOx precursors evolving during rapid pyrolysis of lignocellulosic industrial biomass wastes[J]. Fuel, 2017, 207:438-448. doi: 10.1016/j.fuel.2017.06.046 [28] YU Q Z, BRAGE C, CHEN G X, SJOSTROM K. The fate of fuel-nitrogen during gasification of biomass in a pressurised fluidised bed gasifier[J]. Fuel, 2007, 86(4):611-618. doi: 10.1016/j.fuel.2006.08.007 [29] REN Q Q. NOx and N2O precursors from co-pyrolysis of biomass and sludge[J]. J Therm Anal Calorim, 2013, 112(2):997-1002. doi: 10.1007/s10973-012-2645-3 [30] 刘海明, 张军营, 郑楚光, 孟韵.煤中吡咯型和吡啶型氮热解稳定性研究[J].华中科技大学学报自然科学版, 2004, 32(11):13-15. http://www.cqvip.com/QK/90344A/2004011/11305928.htmlLIU Hai-ming, ZHANG Jun-ying, ZHENG Chu-guang, MENG Yun. Quantum chemical study of the pyrolysis stability of pyrrolic nitrogen and pyridinic nitrogen in coal[J]. J Huazhong Univ Sci Technol:Nat Sci Ed, 2004, 32(11):13-15. http://www.cqvip.com/QK/90344A/2004011/11305928.html [31] VERMEULEN I, BLOCK C, VANDECASTEELE C. Estimation of fuel-nitrogen oxide emissions from the element composition of the solid or waste fuel[J]. Fuel, 2012, 94(1):75-80. http://www.sciencedirect.com/science/article/pii/S001623611100785X?via%3Dihub -
点击查看大图
计量
- 文章访问数: 185
- HTML全文浏览量: 35
- PDF下载量: 17
- 被引次数: 0
