石化污泥与煤混烧的流化床多环芳烃排放特性

在一座密相区截面为0.23 m×0.23 m、高度为7 m的循环流化床试验装置上进行了石化污泥与煤混烧多环芳烃排放特性的系统性试验研究.结果表明,污泥中多环芳烃含量远高于煤;随着二次风率的增大,烟气、飞灰和底渣中多环芳烃排放量均呈明显的下降趋势;随着空气过剩系数的增大,多环芳烃排放水平先下降后上升:石灰石的添加能有效抑制多环芳烃的生成,随着ca/S摩尔比增大,多环芳烃排放水平显著下降.各工况均以排放低环多环芳烃为主,且飞灰中多环芳烃排放量远高于底渣.     

燃烧方式对塑料垃圾燃烧时PAHs和PCDD／Fs排放的影响

为了找出燃烧方式对塑料垃圾焚烧过程中多环芳烃和二恶英排放的影响,在两种不同类型试验用燃烧反应器上进行了聚氯乙烯的燃烧试验.燃烧的烟气参考GB 86-5119和USEPA1613方法采用色质联用分析仪收集分析,对烟气中多环芳烃和二恶英的分布特征进行了观察.结果显示,聚氯乙烯在流化床燃烧反应器上燃烧时生成的多环芳烃和二恶英的总量要明显低于固定床燃烧反应器上的生成量.流化床燃烧方式能够抑制多环芳烃和二恶英的某些发生机制.多环芳烃和二恶英排放特征的关联关系非常明显,可以作为塑料垃圾燃烧过程中产生的二恶英的实时监测替代物.     

不同煤燃烧方式多环芳烃生成特性的研究

研究比较了不同煤燃烧方式多环芳烃生成特性。固定床煤燃烧多环芳烃生成随温度升高出现了先增加后减少的趋势，流化床煤燃烧多环芳烃生成随温度升高而增加。流化床煤燃烧多环芳烃生成量要少于固定床燃烧方式，总量上低1～2个数量级。固定床燃烧(管式炉等)PAHs低温由热解生成，高温由前驱物生成。流化床燃烧PAHs低温由高环芳香性物质的热分解和缩聚反应生成，高温由小分子烃类的聚合。图12表1参13     

不同煤种燃烧生成多环芳烃的研究

燃煤过程产生的多环芳烃类有机污染物烃具有强烈的致癌、致突变、致畸变等作用 ,日益受到广泛的重视。本文进行了不同煤种燃烧时多环芳烃的生成研究 ,比较了燃煤排放和原煤中含有的多环芳烃之间关系 ,研究了煤的固定碳、挥发份、灰份等组分对燃煤过程中多环芳烃排放的影响     

不同煤种燃烧生态多环芳烃的研究

燃煤过程产生的多环芳烃类有机污染物烃具有强烈的致癌、致突变、致畸变等作用，日益受到广泛的重视。本文进行了不同煤种燃烧时多环芳烃的生成研究，比较了燃煤排放和原煤中含有的多环芳烃之间关系，研究了煤的固定碳、挥发份、灰份等组分对燃煤过程中多环芳烃排放的影响。     

分层当量比混合气抑制爆震的燃烧排放特性研究

针对汽油缸内直喷式(GDI)发动机,利用两次喷射策略形成分层当量比混合气抑制爆震的思路进行了研究,着重分析了两次喷射策略中第二次喷射时刻和比例对燃烧、爆震和排放的影响,并对比了分层当量比混合气与传统的推迟点火时刻和加浓混合气抑制爆震方法的燃烧排放特性差异.研究结果表明:分层当量比混合气能够实现抑制爆震的效果,且浓区混合均匀时可减弱分层对燃烧效率和平均指示压力的降低;分层当量比混合气可利用三效催化剂高效地降低HC、CO和NOx的排放;分层混合气会由于混合不均造成碳烟生成,分区均质的分层混合气组织形式将有助于降低分层带来的碳烟排放;分层当量比混合气抑制爆震可减弱推迟点火时刻对负荷的降低;与加浓抑制爆震方法相比,可显著提高燃油经济性并降低排放.     

流化床焚烧塑料垃圾多环芳烃的生成特性

研究了典型塑料垃圾PVC、PE和PS在流化床燃烧过程中多环芳烃的排放特性,分析了多环芳烃生成量随燃烧温度变化的情况.结果表明,PS燃烧产生多环芳烃随温度呈现单峰变化,800℃时最高;PVC则随温度呈指数减少的趋势;PE变化较为复杂.从总量看,多环芳烃生成量大小顺序为PS>PVC>PE.     

石化污泥与煤混烧时多环芳烃的排放特性

在管式固定床上进行了石化污泥与煤的混烧试验,着重研究了质量掺混比、燃烧温度和燃烧停留时间等因素对底渣中多环芳烃排放的影响.结果表明:随着污泥质量掺混比的增大,底渣中多环芳烃排放量呈明显上升态势;随着燃烧温度的升高,多环芳烃排放量先上升后下降;随着燃烧停留时间的增加,多环芳烃排放量呈明显的下降趋势,且存在一个临界停留时间.在各种工况条件下,低环多环芳烃排放量均高于高环多环芳烃排放量.     

塑料掺煤流化床燃烧二噁(口英)排放的试验研究咂

对塑料颗粒、塑料颗粒和煤在小型流化床试验台中进行了燃烧试验，对燃烧产生的烟气进行采集，采用HRCC—LRMS方法对样品进行预处理和分析，得到了试验中的二噁Ying排放因子。试验发现，单纯燃烧PVC颖粒，燃烧条件不好时，二噁Ying总量排放因子为252．69ng／g，毒性当量(TEQ)排放因子为4．60ng／g；添加煤燃烧后，二噁Ying总量排放因子为79．72ng／g，毒性当量排放因子为2．41ng／g，抑制效率分别达到68．5％和47．6%。而PVC／PE混烧时，燃烧条件改善后，二噁Ying排放因子为1．76ng／g，毒性当量排放因子为0．11ng／g；添加煤燃烧后，二噁Ying总量排放因子为2．57ng／g，毒性当量排放因子为0．03ng／g，抑制效率分别达到—46％和72．7米由试验结果可见，煤的添加对于含氮塑料燃烧产生的二噁Ying毒性当量排放因子具有较好的抑制效果，而对二噁Ying总量排放因子的抑制作用得到了不同的结果。     

不同煤种混煤燃烧时NO_x生成和燃尽特性的试验

在一维沉降炉上对无烟煤、贫煤、烟煤及其混煤的燃烧特性进行了研究，分析了不同因素对NOx排放量的影响，并讨论了不同过量空气系数、掺混比及一、二次风比例对燃尽率的影响，试验结果表明：当烟煤的掺混比例为25％，NOx的排放量较低，混煤燃烧时沿程分析结果表明，煤种特性的不同导致NOx排放时有不同的峰值。     

低NO_x燃烧与脱硝经济运行的实践

吴泾热电厂2×300MW级燃煤供热机组脱硝设备,采用低NOx燃烧加选择性催化还原法(SCR)脱硝系统。介绍了SCR的化学反应机理、反应器安装位置、分段配风燃烧技术,分析了低NOx燃烧工况和运行参数,结果证实了:对分段配风的低NOx燃烧器来说,有效控制主燃烧区的风量,在总风量不变的条件下,加大可水平摆动的分离燃烧器(SOFA)配风量和加大SOFA配风距离是有效降低NOx的生成、减轻SCR的负载、降低耗NH3的有效方式;当燃用低值煤和可磨性差煤,使相对一次风量增加时,应降低二次风的配风量,用一次风总量自动实时修正二次风的配风量是实现自动低NOx燃烧调整的有效途径;适当降低二次风与炉膛的差压是防止二次风配风不均和控制主燃烧区风量的有效方法。     

分级燃烧最佳一次风空气系数的实研究

在一维煤粉燃烧炉上进行了不同煤种、不同细度的分级燃烧试验。实验发现，分级燃烧对高挥发份 煤种以及同一煤种的细煤粉的Nox排放浓度的降低效果更显著，而且在分级燃烧条件下，同一煤种细煤粉的 飞灰含量较粗煤粉低。另外，还得到了不同煤种在分级燃烧条件下的最佳一次风空气系数。图9表2参3     

Comparison of staged combustion properties between bituminous coals and a low-rank coal; Fiber-shaped crystallized carbon formation,NOx emission and coal burnout properties at very high temperature

Previously, we developed a new-concept for a drop-tube furnace in order to investigate staged combustion properties for pulverized coals. Two high-temperature electric furnaces were connected in series. Coal was burnt under fuel-rich conditions in the first furnace, then, staged air was supplied at the connection between the two furnaces. In the present study, we investigated influence of burning temperature on NOx emission and combustion efficiency by using the furnace. The influence of the temperature differed between hv-bituminous coals and a sub-bituminous coal. For the hv-bituminous coals, combustion efficiency was improved when burning temperature in the fuel-rich region rose. When combustion efficiency was improved, NOx emission decreased. The NOx reduction reaction in the fuel-rich region was promoted by increasing the burning temperature in this region. On the other hand, NOx emission increased for the sub-bituminous coal when the temperature was higher than 1800 K. Usually, combustion efficiency was increased with burning temperature. However, combustion efficiency lowered for the sub-bituminous coal when burning temperature was higher than 1900 K. We observed the ash obtained by this temperature condition using Scanning Electron Microscope (SEM) and, Transmission Electron Microscope (TEM) and observed fiber shaped carbon. The difference in NOx properties was derived as a difference of hydrocarbon concentration. For low-rank coals (sub-bituminous or lignite), the hydrocarbon formation rate was smaller than that for hv-bituminous coals. When the hydrocarbon contribution to the NOx reduction reaction was large, NOx emission decreased with increasing burning temperature; however, hydrocarbon content in volatile matter was small for low-rank coals.     

煤与生物质混烧时NO_x排放特性的实验研究

叙述了将稻壳、麦秆、松木屑3种生物质,分别与阳泉煤掺烧时,不同掺混比与过量空气系数对NOx排放规律的影响。指出,在低含O2量区,无论单煤还是混合燃料,NOx浓度均随烟气中的含O2量增加而增大;不同燃料NOx浓度增长速度的快慢,随烟气中的含O2量增加有所不同;在高含O2量区,混合燃料NOx的排放量随烟气中含O2量的增加而降低;生物质与煤掺混对NOx排放规律的影响不明显,燃烧过程中NOx的排放受生物质本身的含N量、煤种以及燃烧方式的影响较大。     

低NOx排放燃烧技术及燃烧优化的试验研究

介绍了煤燃烧过程中NOx生成机理和电站锅炉采用低NOx燃烧技术.通过对某电厂670 t/h锅炉进行炉膛出口氧量、一次风速、二次风配风方式、燃烧器上、下组的给粉方式、一次风煤粉浓淡比等对NOx排放量、飞灰可燃物含量和锅炉再热蒸汽温度的影响规律的试验研究.得出水平浓淡风煤粉燃烧技术能降低NOx排放量,确定了给出锅炉优化运行方式.试验结果表明燃烧优化调整是提高锅炉运行的经济性和降低NOx排放量的有效方法.     

Mechanism analysis on the pulverized coal combustion flame stability and NOx emission in a swirl burner with deep air staging

Low NOx burner and air staged combustion are widely applied to control NOx emission in coal-fired power plants. The gas-solid two-phase flow, pulverized coal combustion and NOx emission characteristics of a single low NOx swirl burner in an existing coal-fired boiler was numerically simulated to analyze the mechanisms of flame stability and in-flame NOx reduction. And the detailed NOx formation and reduction model under fuel rich conditions was employed to optimize NOx emissions for the low NOx burner with air staged combustion of different burner stoichiometric ratios. The results show that the specially-designed swirl burner structures including the pulverized coal concentrator, flame stabilizing ring and baffle plate create an ignition region of high gas temperature, proper oxygen concentration and high pulverized coal concentration near the annular recirculation zone at the burner outlet for flame stability. At the same time, the annular recirculation zone is generated between the primary and secondary air jets to promote the rapid ignition and combustion of pulverized coal particles to consume oxygen, and then a reducing region is formed as fuel-rich environment to contribute to in-flame NO_X reduction. Moreover, the NOx concentration at the outlet of the combustion chamber is greatly reduced when the deep air staged combustion with the burner stoichiometric ratio of 0.75 is adopted, and the CO concentration at the outlet of the combustion chamber can be maintained simultaneously at a low level through the over-fired air injection of high velocity to enhance the mixing of the fresh air with the flue gas, which can provide the optimal solution for lower NOx emission in the existing coal-fired boilers.     

炉内配风方式对燃烧特性影响的数值模拟与试验研究

为了了解不同配风工况对炉内煤粉燃烧特性的影响,以四角切圆燃烧煤粉锅炉为研究对象,分别对其进行了炉内流动、燃烧过程的数值模拟及优化燃烧调整试验,综合分析数值模拟和试验的结果表明:当机组负荷一定时,适当减少一次风率,能使整个炉膛火焰充满度大大得到改善,火焰长度与煤粉着火距离有所缩短;采用倒宝塔型二次风配风方式对于较差煤种的稳定着火较为有利;而停止三次风时,炉膛温度水平较高,煤粉燃烧完全,锅炉效率有所提高.     

旋流燃烧器的稳燃及其结构优化分析

简要叙述了国内常见几种旋流燃烧器的稳燃措施，从燃烧器流场和煤粉颗粒运动轨迹的角度分析了对低挥发份煤燃烧稳定性的影响。介绍了新近研究的花瓣稳燃器及其流场特点。指出该稳燃器在加速煤粉气流与高温回流烟气之间的混合时，避免煤粉气流过早向二次风扩散，引导煤粉颗粒进入回流区，有利于燃用低挥发份煤和低负荷稳燃及降低NOx排放等。另外，还介绍了ABT公司最近推出的“弓形”低NOx燃烧器；最后，提出了旋流燃烧器，并提出了旋流燃烧器结构优化的建议。     

Emission of particulate matter and polycyclic aromatic hydrocarbons from select cookstove–fuel systems in Asia

Emission of particulate matter (PM) and polycylic aromatic hydrocarbons (PAH) from 12 selected cookstoves in Asia burning wood fuel, rice husk briquettes and anthracite coal was investigated. Monitoring was conducted using a hood and a semi-VOC sampling train. 17 PAH (16 US EPA priority plus BeP) were analyzed by HPLC-UV to yield PAH in the PM and gas phase samples separately. PM emission factor for wood fuel, rice husk briquettes and anthracite coal, is around 2– and , respectively. Emission factor of 17 PAH for the two biomass fuels is 24– and , respectively. The majority of PAH in the biomass fuel smoke is of light and more volatile PAH with above 86% of the total 17 PAH found in the vapor phase. For the anthracite coal emission factor of 17 PAH was low and found only in the PM phase. PAH content of PM varies with cookstoves and is 0.08– (of PM) for total 17 PAH, 0.06– for genotoxic PAH, and 0.001– for BaP alone. Emission data from this study was collated with those previously presented, which provides a broader emission database for domestic combustion.