Optimization of decoupling combustion characteristics of coal briquettes and biomass pellets in household stoves

Burning coal briquettes or biomass pellets in household decoupling stoves is of significance to the reduction of residential pollutant emissions such as NO and CO. In order to make full use of the superiority of decoupling combustion technology, the household stoves should be specially designed and optimized to adapt to fuel types and combustion characteristics. Using numerical simulation and experimental validation, this study quantitatively clarified that the reducibility of devolatilization char plays an important role in the suppression of NO emission in the decoupling combustion of coal, while the reducibility of pyrolysis gases has a dominant effect on the reduction of NO in the decoupling combustion of biomass. An optimal parameter combination of throat height and grate angle was obtained for the simultaneous suppression of NO and CO emissions in the household decoupling stove burning coal briquettes. Two types of decoupling stoves were developed to enable the clean combustion of biomass pellets. The A-type biomass stove with a multi-pass smoke tunnel shows a better comprehensive NO and CO reduction effectiveness than the B-type biomass stove consisting of a two-stage grate structure and an S-shaped pyrolysis chamber. The optimal structural parameters provided references for the design and manufacture of commercial decoupling coal and biomass stoves.

A new forecast model for the carbon-monoxide concentration in the upper corner of mining face

The CO gas in the upper comer along with the work of mining face in different coal-seam of Lingwu coal-field has deeply affected judgment for the degree of the coal spontaneous combustion and safety work. For this issue, a new calculation and forecast model of the carbon monoxide concentration in the upper comer of mining face was deduced for analyzing and calculating the date from the lab and test-in-place, during this course using the knowledge of heat transfer, fluid dynamics, and mathematics. The model took into account the characteristics of the coal spontaneous combustion, coal mining conditions, and other correlate factors, so the CO concentration of the upper comer safe under the normal condition, and it is in danger when the coal reached spontaneous combustion, which can be calculated accurately with the model and compared with the measured concentration with a tolerance of less than 12%.

Using KELEA (Kinetic Energy Limiting Electrostatic Attraction) to Improve the Efficiency of Fuel Combustion

There are many reports of devices and fuel additives being able to enhance the performance of automobiles and other forms of transportation that rely upon the combustion of gasoline or diesel fuels. The claims extend from increased mileage and power to significant reductions in toxic exhaust emissions of carbon monoxide and unburnt hydrocarbons. Progress towards more widespread applications of means of improving fuel efficiency has been impeded by the lack of a coherent explanation of the mechanism of action. Fuel combustion allows for the conversion of much of the available chemical energy in volatile hydrocarbons to mechanical energy, which moves the pistons within an engine. It is proposed that the amount of chemical energy in hydrocarbons can be increased by the absorption of an environmental force termed KELEA (kinetic energy limiting electrostatic attraction). In addition to providing greater mechanical energy with relatively less heat output, the combustion of KELEA activated fuels proceeds further with less toxic emissions of carbon monoxide and unburnt hydrocarbons from incomplete combustion. KELEA activation of fuels should become standard practice in the transportation industry, with potential additional benefits in slowing the rate of global warming.

Performance and kinetics of iron-based oxygen carriers reduced by carbon monoxide for chemical looping combustion

Chemical looping combustion is a promising technology for energy conversion due to its low-carbon, high-efficiency, and environmental-friendly feature. A vital issue for CLC process is the development of oxygen carrier, since it must have sufficient reactivity. The mechanism and kinetics of CO reduction on iron-based oxygen carriers namely pure Fe2O3 and Fe2O3 supported by alumina （Fe2O3/Al2O3） were investigated using thermo-gravimetric analysis. Fe2O3/Al2O3 showed better reactivity over bare Fe2O3 toward CO reduction. This was well supported by the observed higher rate constant for FezO3/Al2O3 over pure Fe2O3 with respective activation energy of 41.1±2.0 and 33.3±0.8 kJ. mol^-1. The proposed models were compared via statistical approach comprising Akaike information criterion with correction coupled with F-test. The phase-boundary reaction and diffusion control models approximated to 95% confidence level along with scanning electron microscopy results; revealed the promis- ing reduction reactions of pure Fe203 and Fe2O3/Al2O3. The boosting recital of iron-based oxygen carrier support toward efficient chemical looping combustion could be explained accurately through the present study.

前后墙对冲锅炉燃烧优化系统应用的经济性分析

以某发电站前后墙对冲锅炉为研究对象,对锅炉的热效率与烟气中一氧化碳(CO)浓度的关系进行研究,建立基于CO监测的锅炉燃烧优化系统,并将系统应用于某电厂当中,对实际运行效果和经济性进行分析。

MnO_(2)-CeO_(2)纳米复合材料的制备及其对CO的净化催化性能

采用溶液燃烧法制备层状多孔结构MnO_(2)-CeO_(2)纳米复合材料。催化氧化实验表征产物结果表明,相较于纯CeO_(2),MnO_(2)-CeO_(2)纳米复合材料催化氧化CO性能明显提升:当复合材料(MnO_(2))所占百分比为30%时,CO的转化温度最低,有望成为低成本高性能的新型CO催化剂。

Self-sustained catalytic combustion of CO enhanced by micro fluidized bed: stability operation, fluidization state and CFD simulation

A micro fluidized bed reactor was used to study the self-sustaining catalytic combustion of carbon monoxide(CO).The Cu_(1−x)Ce_(x)O_(y) catalyst,as well as the pure CuO and CeO_(2),are used to investigate the contributing mechanism of different active sites including dispersed CuO and Cu–Ce solid solutions.The ignition temperature(Ti)of CO over these catalysts at a flow rate of 2000 mL/min followed the order:74℃(Cu_(0.5)Ce_(0.5)O_(y))<75℃(Cu_(0.25)Ce_(0.75)O_(y))<84℃(Cu_(0.75)Ce_(0.25)O_(y))<105℃(CuO)<500℃(CeO_(2)).Furthermore,the lean combustion limits(equivalence ratioϕ)over these catalysts under the flow rates of 750–3000 mL/min(through fixed,bubbling,and fluidized bed)were also measured,which are Cu_(0.5)Ce_(0.5)O_(y)<Cu_(0.25)Ce_(0.75)Oy<Cu_(0.75)Ce_(0.25)O_(y)<CuO<CeO_(2).The fluidized bed was simulated using the Eulerian two-fluid model(TFM)coupled with a diffusion/kinetic-limited reaction model to evaluate the influence of operation conditions on the self-sustained combustion of CO.The predicted maximum temperature agreed with the experimental measurements,demonstrating the validity of the kinetic model and simulation parameters.The results of catalytic combustion with increasing CO concentrations suggest that the catalytic combustion reaction could co-exist with the flamed combustion.When a high concentration of CO is used,a blue-purple flame caused by CO combustion appears in the upper part of the fluidized bed,indicating that the range of CO-containing exhaust gas purification could be expanded to a larger range using the fluidized-bed catalytic combustion technique.

常见地板燃烧特性研究与分析

选取目前市场上常用的11种地板作为研究对象,采用锥形量热仪研究了引燃时间、热释放速率、火灾性能指数、总热释放量、有效燃烧热、CO生成量等燃烧特性参数。试验结果及分析表明:11种地板火灾安全性从高到低依次为:栗木、番龙眼、槐木、柞木、白橡木、榆木、刨花板、中密度纤维板、高密度纤维板、枫桦木、楠竹;试样燃烧为4个阶段:一次猛烈燃烧阶段,一次燃烧衰减阶段,二次猛烈燃烧阶段,二次燃烧衰减阶段;11种试样的有效燃烧热数值较为接近,基本在12 MJ/kg左右,且在试验过程中的CO生成量稳定在17×10^(-6)左右。

Catalytic oxidation of carbon monoxide, toluene, and ethyl acetate over the xPd/OMS-2 catalysts： Effect of Pd loading

The Pd catalyst supported on cryptomelanetype manganese oxide octahedral molecular sieve （OMS- 2） were prepared. The effect of Pd loading on the catalytic oxidation of carbon monoxide, toluene, and ethyl acetate over xPd/OMS-2 has been investigated. The results show that the Pd loading plays an important role on the physicochemical properties of the xPd/OMS-2 catalysts which outperform the Pd-free counterpart with the 0.5Pd/ OMS-2 catalyst being the best. The temperature for 50% conversion was 25, 240 and 160 ℃, and the temperature for 90% conversion was 55,285 and 200 ℃ for oxidation of CO, toluene, and ethyl acetate, respectively. The low- temperature reducibility and high oxygen mobility ofxPd/ OMS-2 are the factors contributable to the excellent catalytic performance of 0.5Pd/OMS-2.

蒸汽喷吹烧结填充床强化碳燃烧:减少一氧化碳排放的实验研究

提高固体燃料的燃烧效率对减少铁矿石烧结过程中的一氧化碳排放具有重要意义。本研究借助蒸汽对焦炭燃烧的辅助作用,在烧结过程中引入表面蒸汽喷吹技术,并验证了该技术在降低一氧化碳排放方面的潜力。首先,在空气与空气-蒸汽混合气氛中分别进行焦炭的热重实验。结果表明,相比于空气气氛,引入蒸汽后的混合气氛可使燃烧废气中的一氧化碳浓度从183×10^(-6)降低到78×10^(-6)。此外,从热力学和动力学角度分析了表面蒸汽喷吹技术减少一氧化碳排放的机理。然后,在无喷吹、间隔喷吹与连续喷吹操作下,进行了一系列实验室规模下的烧结杯试验。结果表明,间隔喷吹和连续喷吹均可降低烧结过程中的一氧化碳排放。在本试验条件下,蒸汽喷吹的最佳方式为以0.053 m^(3)/min的喷吹流量连续喷吹13 min。与无喷吹案例相比,烧结废气中一氧化碳的平均浓度从7565×10^(-6)降低到6231×10^(-6),烧结矿的一氧化碳总排放量则从13.46 m^(3)/t降低到9.51 m^(3)/t。

液态碳酐相变降温惰化防灭火技术实践

液体碳酐相变防灭火技术兼顾降温与惰化2种性能,对防控易自燃煤层综放工作面停采撤架期间遗煤自燃灾害具有良好的治理效果。以鄂尔多斯矿区某矿综放工作面为研究对象,在现有防灭火注惰系统技术工艺的基础上,依据液态碳酐气化过程中易结冰的三相点理论,同时结合工作面停采撤架期间防灭火问题的复杂性,设计并施工了井上、下长距离液态碳酐压注系统,重点对采空区内距离停采线100 m、150 m区域进行间断式压注液态碳酐,压注液态碳酐累计398 t。现场应用结果表明,完成液态碳酐压注后,上隅角、工作面2处重点监测区域CO浓度均处于30×10^(-6)以下,回风流处CO浓度处于15×10^(-6)以下,在距离停采线130 m、150 m、170 m这3处测温点的温度均呈现明显的下降趋势,初步达到防灭火工作预期,为工作面的回撤安全提供了技术支撑。

燃气锅炉不完全燃烧现象的分析

不完全燃烧现象在燃气锅炉燃烧中十分常见。文中以一台燃气锅炉的不完全燃烧后出现积碳现象为案例,详细分析了不完全燃烧产生的原因及存在的危害,并提出了判断不完全燃烧的方法,期望能为燃气锅炉的科学燃烧提供一定的指导和帮助。

RE PEROFSKITE CATALYSTS FOR OXIDATION OF CARBON MONOXIDE

Ⅰ. INTRODUCTIONThe catalysts commonly used abroad for oxidation of carbon monoxide are those containing platinum, palladium or other noble metals. They are used for purification of the exhaust of automobiles and chimneys of electric power plants, for oxidation of hydrocarbons and as combustion promoters ia the regeneration of cracking catalysts.

基于程序升温的煤自燃临界温度测试方法

针对绝热氧化法测试临界温度周期长的不足,以缩短测试时间为切入点,建立了利用CO浓度与温度的变化求解临界温度的计算模型,提出了基于程序升温条件下的煤自燃临界温度测试方法。在此基础上,采用课题组研制的实验设备对3种不同变质程度的煤样进行了实验计算,并将计算结果与绝热条件下所得的临界温度值进行分析比较。结果表明:基于程序升温方法得到的煤自燃临界温度与绝热方法的测试结果基本一致,且测试周期短,单个煤样测试时间不超过3.5h。

固定床上Fe_2O_3载氧燃烧特性实验研究

Fe2O3作为载氧体可以在载氧燃烧过程中实现CO2的分离。在固定床试验台(内径40mm,高1600mm)上,通过改变载氧体在反应器中所处的还原氧化氛围模拟载氧燃烧过程,研究载氧体Fe2O3的载氧燃烧特性。实验载氧体量385g,CO+CO2+N2为还原气体,O2+N2为氧化气体。在900℃下针对CO2对反应的影响进行研究,对载氧体粒径和反应温度的影响进行探讨。为了分析载氧体的反应活性与稳定性,在900℃下对载氧体颗粒进行多次还原氧化循环实验。结果表明,在纯CO的氛围下,Boudouard反应会导致还原过程发生析碳,CO还原气中加入CO2可以抑制析碳的产生。还原反应中载氧体颗粒的比表面积和孔隙率越大,CO的转化率越高。在Fe2O3-Fe3O4阶段,高温不利于CO的转化,但有助于CO在Fe3O4-Fe0.947O/Fe阶段中的转换。通过5～6次的循环实验发现,载氧体在经过第1次反应后会出现一定程度的失活,此后性质保持稳定。

惰质组与镜质组对煤吸附CO性能的影响

针对许多中、低变质程度的煤层出现CO长期超标,但未出现自然发火的现象,对24种不同变质程度的煤样进行了CO等温(30℃)吸附实验以及煤岩显微组分分析.研究表明:煤的镜质组含量、惰质组含量对CO吸附量影响较大,且对于中、低变质程度的煤,惰质组对煤吸附CO的影响大于镜质组对CO吸附的影响.利用Mathematic软件对实验数据进行分析处理,得出在不同压力下,惰质组含量与吸附量之间的数学模型.

Co-Fe_2O_3纳米载氧体作用下CO化学链燃烧富集CO_2

制备了不同量级Co掺杂Fe2O3载氧体Co-Fe2O3，利用BET和TEM对载氧体结构进行表征。通过在不同温度下Co-Fe2O3与气体燃料CO的还原反应，考察Co-Fe2O3对CO化学链燃烧特性。结果表明，同一温度条件下，掺杂量越高，还原反应转化率越高；掺杂量不变的情况下，温度升高促使还原程度加深，缩短了载氧体完全还原转化的时间。根据TGA曲线进行了化学动力学分析，发现Co0.2Fe还原反应过程在344.7～391.0℃和414.7～472.5℃温度范围反应动力学对应扩散控制的 Jander 方程模型，607.6～681.5℃温度范围对应二维扩散反应模型，并分别计算出相应模型的表观活化能和频率因子。结果可为化学链燃烧技术应用提供理论指导。

水蒸气纯氧条件下合成气燃烧特性

水蒸气纯氧燃烧技术因具有高效零污染物排放的特点而备受关注,对合成气在水蒸气纯氧条件下的燃烧特性进行了实验研究。在扩散燃烧实验台上测量了H2O/O2为2.0时,燃烧室中心气体成分和火焰温度随停留时间的变化规律,分析了过量氧气系数对合成气水蒸气纯氧燃烧过程的影响。研究结果表明:过量氧气系数为0时,H2和CO的燃烧主要在前28 ms内,H2的燃烧速率较快,能够快速燃尽;CO燃烧较慢,燃烧室出口含量依然很高。过量氧气系数从0增大到10%时,CO的浓度整体降低,燃烧速率提高,燃烧前期火焰温度提高。燃烧室出口CO浓度随过量氧气系数的增加逐渐降低,氧气微过量时CO浓度迅速下降,继续增大时,燃烧室出口CO的浓度下降缓慢。

家用燃料气态燃烧产物对室内空气污染的初步评估

目的初步评估天然气、液化石油气和蜂窝煤的气态燃烧产物对室内空气污染的影响程度和特征。方法在特别设计的3间实验房间内分别使用天然气、液化石油气和蜂窝煤在室内进行定量燃烧,同时根据国家标准方法采集空气样品并测定SO2、NO2、CO和甲醛的浓度,对其排放量和排放特征进行分析。结果3种燃料的气态燃烧产物(SO2、NO2、CO、甲醛)中,均以CO和NO2的排放量最高。在日均用量下,蜂窝煤的CO和NO2排放量远高于天然气和液化石油气。使用蜂窝煤的家庭CO单位排放量高达30136mg/kg,明显高于液化石油气(8725mg/kg)和天然气(2755mg/kg);液化石油气的NO2单位排放量(42.69mg/kg)则明显高于蜂窝煤(20.01mg/kg)和天然气(11.87mg/m3)。在通风不良的室内,均可使室内CO和NO2浓度均超过GB/T18883—2002《室内空气质量标准》。结论厨房室内燃烧天然气或液化石油气,能造成CO和NO2的污染。

用于低浓度一氧化碳去除的流向变换系统

为探究将流向变换技术应用于低浓度一氧化碳处理的可行性,自制了一种整体式催化剂并将其应用于小型流向变换催化燃烧装置.采用预处理后的堇青石蜂窝陶瓷为支撑体,改性γ-Al2O3为催化剂载体,添加Ce、La等轻稀土元素作为助剂,研究制备出性能优良的贵金属Pd整体式催化剂.研究中考察了催化剂预热温度对催化剂效率的影响及反应系统换向周期、空速等条件对反应系统床层温度的影响.研究结果表明:当催化剂预热温度为200℃、换向周期为8 min、空速为8 000 h^(-1)、一氧化碳初始体积分数为0.1%时,一氧化碳转化率最高可达90%.