半焦与垃圾衍生燃料混烧的排放特性

在非均匀布风流化床中进行了半焦与垃圾衍生燃料（RDF）的混合燃烧实验，研究了不同半焦混烧率对烟气组分的影响以及二者混烧的可行性与经济性．实验结果表明，随着半焦混烧率的增加，H2O（气态）、CO、HCl、NO及C3H6含量均呈下降趋势，而CO2、SO2含量则呈增加趋势．同时发现，在燃烧过程中增加C1元素含量，可以促进NO的生成．     

生物质循环流化床内树皮与煤混烧的试验研究

分别在热重分析仪和在35.5 kW生物质循环流化床实验平台上进行了树皮和煤的混合燃烧试验,热重试验表明:在树皮中添加质量分数为5%~15%的煤后,混烧时失重速率(DTG)曲线和纯树皮类似,仍呈现双峰特性,但挥发分燃烧峰变小,固定碳燃烧峰稍有增大,着火温度趋向于接近树皮的着火温度,燃烬温度趋向于接近煤的燃烬温度。在循环流化床的燃烧试验表明:相比于树皮单独燃烧,混烧可使燃料沿炉膛放热更均衡,燃烧更稳定,同时降低了CO排放,但NOX,SO2等污染物浓度有不同程度的增加。由于煤灰具有较好的固氯效果,烟气中HCl浓度和飞灰中Cl含量均显著减少。通过热重试验和循环流化床热态试验,得出煤的最佳添加量应为5%~10%。     

城市生活垃圾_MSW_与煤混烧过程中气体污染物的排放

人者在0．2MW循环流化床上进行了城市生活垃圾与煤混烧实验。在线测量了NOx,NO,N2O,SO4,HCl和Cl2排放浓度，探讨了城市生活垃圾与煤掺煤比（R）和温度对气体污染物排放的影响。实验结果显示，在混烧过程中，随拉圾加入量的增加，NOx,NO,N2O和SO4排放量减少，Cl2排放浓度啬 。当掺烧比R不变，温度增加时，NOx，NO排放量增加，N2O排放减少，SO2，HCl和Cl2排放浓度基本不变，飞灰和底渣中二恶英含量减少。     

城市垃圾与高硫煤混烧排放特性的模拟

运用正交实验设计的方法，在DTA-TG-DTG设备上研究了城市垃圾与高硫煤模拟混合物的燃烧排放特性。用NaCl替代垃圾中的多种氯化物成分，将NaCl添加到铜川煤中组成模拟混合物模拟城市垃圾与高硫煤的混合物。所有模拟混合物样品分别置于DTA-TG-DTG的燃烧室中燃烧，同时利用烟气分析仪在烟气排放口监测烟气。另外，将NaCl和CaCO3同时添加到煤中，研究了NaCl对SO2吸收剂吸收性能的影响。结果表明，NaCl能够降低高硫煤在燃烧过程中的SO2排放量；NaCl能够改善CaCO3对SO2的吸收性能，增强吸收剂的吸收能力。发展垃圾与高硫煤混合燃烧技术并同时使用SO2吸收剂，可降低SO2排放量，减轻设备腐蚀及环境污染。     

石化污泥与煤流化床混烧SO_2的排放特性

在一座热输入量为0.2 MW的循环流化床试验台上进行了石化污泥与煤的混烧试验,重点考察了质量掺混比、空气过剩系数、二次风率、Ca/S摩尔比、床温等因素对SO2排放的影响.试验结果表明,随着质量掺混比或者空气过剩系数的增加,SO2的排放质量浓度均呈下降趋势;在空气过剩系数保持不变的条件下,随着二次风率的增加,SO2排放浓度上升;脱硫剂石灰石的添加能有效降低SO2的排放,且SO2的排放浓度随着Ca/S摩尔比的增大而显著下降;随着床层温度的升高,SO2的排放质量浓度呈先下降后土升趋势,存在一个最佳脱硫区.     

循环流化床富氧燃烧技术的试验研究

富氧燃烧技术不仅能使分离收集CO2和处理SO2容易进行,还能减少NOx排放,是一种能够综合控制燃煤污染物排放的新型洁净燃烧技术。简要介绍了循环流化床富氧燃烧技术的国内外研究现状,进行了不同氧含量的O2/CO2气氛和O2/N2气氛下的循环流化床煤燃烧试验研究,比较了其燃烧特性及SO2、NOx排放特点,为循环流化床富氧燃烧技术的工业化应用做了基础和重要的准备。     

O2/CO2气氛下循环流化床煤燃烧污染物排放的试验研究

富氧燃烧技术不仅能使分离收集CO2和处理SO2容易进行,还能减少NOX排放,是一种能够综合控制燃煤污染物排放的新型洁净燃烧技术。进行了O2/CO2气氛和O2/N2气氛下的循环流化床煤燃烧试验,重点分析了煤燃烧生成的污染物NOX、SO2的排放规律及石灰石脱硫效率,进行了循环流化床富氧燃烧系统的平衡分析并得到了相关试验的证实,为循环流化床富氧燃烧技术的工业应用做了基础和重要的准备。图9表2参9     

燃烧福建无烟煤循环流化床锅炉炉内脱硫对SO2、NOx和CO等污染物排放的影响

在一台燃烧福建无烟煤75t/h循环流化床锅炉上进行炉内添加石灰石脱硫的工业热态试验,测试了Ca/S摩尔比变化对燃烧福建无烟煤循环流化床锅炉炉内脱硫效果以及SO2、NOx、CO等污染物排放的影响.试验表明:燃烧福建无烟煤循环流化床锅炉自脱硫效率较高,并且脱硫效率随着Ca/S摩尔比增大而呈"S"型曲线变化,在Ca/S摩尔比...     

含水/脱水市政污泥与煤混烧的NO和SO2排放特性研究

通过2种市政污泥分别和某电厂实际用煤混烧的试验,研究了污泥的种类、含水率、掺烧比例对混烧时NO和SO2排放的影响规律.试验结果表明:2种污泥与煤掺烧所体现的NO和SO2排放特性有所区别,西污泥的NO和SO2排放总量均要高于东污泥.污泥的含水率会影响排放特性,西污泥含水率越高,NO排放相应增加,SO2的排放减小;而东污泥...     

硫对煤与五氯酚混烧过程二(口恶)英生成影响规律的试验研究

二(口恶)英是环境中的痕量剧毒有机污染物,对人类健康极具危害.本文以垃圾中的典型成份五氯酚(PCP)为研究对象,研究了煤和PCP混烧过程中,元素硫及煤中硫对烟气中二(口恶)英生成的影响.煤的加入(特别是高硫煤的加入)可以明显降低二(口恶)英生成.试验结果表明:煤和PCP混烧时,只要燃料中的S/Cl的摩尔比大于0.4时就能实现对燃烧过程中前驱物生成二(口恶)英反应超过80%的抑制效率,当S/Cl比在0.7～1范围内的抑制效果较好.本文的实验结果对于探明实际垃圾焚烧过程中二(口恶)英的生成机理和影响因素具有重要指导意义.     

Experimental and Numerical Study on Co-combustion Behaviors and NO_x Emission Characteristics of Semi-coke and Coal in a Tangentially Fired Utility Boiler

The utilization of powdery semi-coke as a power fuel in pulverized coal-fired power plants has become a new and potential technique to consume the excess powdery semi-coke.The characteristic of low volatile results in poor combustion performance and high NO_x emission,and to co-fire with bituminous coal is a practical strategy to address this problem.However,the co-combustion characteristics and the inherent interaction between semi-coke and coal remain insufficiently understood.In addition,the influences of secondary air arrangement,the boiler operation load,and the fuel type on co-combustion process are still unclear,which is urgent to be further explored.In the present study,experiments and numerical simulations were jointly utilized to inquire into the co-combustion behaviors and NO_x emission features of semi-coke and coal.The results demonstrated that the"out-furnace method"was a suitable choice for small-capacity boiler when the proportion of semi-coke was 33%,due to the limited combinations of the semi-coke injection position.It was recommended that semi-coke was preferred to be injected from the middle layers of the furnace under the"in-furnace method"to improve the overall co-combustion performance.The critical value of the separated over fire air ratio in this study was 27.5%,over which a slight drop of carbon content in fly ash could come about.Moreover,the elevation in the proportion of separated over fire air gave rise to the significant decline of NO_x concentration.The constricted secondary air arrangement was preferred to be employed due to the high boiler efficiency.The separated over fire air and the surrounding air needed to maintain a wide-open degree to prevent the increase of NO_x emissions and the coking of nozzles.For the load reduction regulation method adopted in this study,the NO_x concentration first rose and then dropped,while the burnout ratio decreased obviously as the operation load was reduced.Different combinations of coal and semi-coke generated significant influences on co-combustion behaviors within the furnace.The NO_(x )generated by high-volatile fuel (bituminous coal) combustion was mainly affected by volatile-N,while the NO_(x )generated by low-volatile fuel (semi-coke) was mainly impacted by char-N.This study is of guiding significance for the efficient and clean utilization and beneficial to the large-scale application of powder semi-coke in power plants.     

Experimental investigation on ignition and burnout characteristics of semi-coke and bituminous coal blends

Ignition and burnout characteristics of semi-coke and bituminous coal blends were investigated by thermogravimetric analyzer and drop tube furnace. The results showed that the ignitability index and the comprehensive combustion characteristic index of the blends decrease as the blending proportion of semi-coke increases, but the average activation energy of the blends increases gradually. Ignition mode of bituminous coal is changed from homogeneous to hetero-homogeneous ignition with the increasing of semi-coke content in the blends. When the mixing proportion of semi-coke is lower than 45%, the burnout rate is lower than the weighted value in the early stage of combustion and gradually higher than the weighted value with the development of combustion process. However, the burnout is always lower than the weighted value to mix with 67% semi-coke. Increasing furnace temperature from 850 °C to 1050 °C can improve the mid-term reaction process, alleviate the negative effects of semi-coke on the co-combustion process and increase the burnout rate. So less than 45% semi-coke blending ratio and increasing furnace temperature are recommended for semi-coke and bituminous coal co-combustion.     

煤与污泥混合物在不同温度下燃烧时SO_2排放特性研究

选取三种煤与污泥的混合物在不同温度下进行加热,分析其SO2排放特性,本研究中温度分别设置为700℃和1000℃,结果表明不同比例的污泥对混合物SO2排放有着重要影响;同时,不同温度对石炭煤的累积SO2排放量有着一定影响,在700℃下,累积SO2排放量为2000~5000 mL/m3,而在1000℃时,其累积排放量为2500~3500 mL/m3,另外,高温能够加快各混合物SO2产生速率。     

Co-combustion of refuse derived fuel with Korean anthracite in a commercial circulating fluidized bed boiler

The effect of co-combustion of Refuse Derived Fuel (RDF) with Korean anthracite on the combustion and environmental performance was observed in the Tonghae commercial Circulating Fluidized Bed (CFB) boiler. High contents of oxygen and CaO in RDF reduced the amount of air required for combustion and the limestone flow rate for SO₂ capture in the CFB boiler, respectively. The temperature in the furnace exit increased slightly due to re-combustion of volatiles which resulted in limiting the co-combustion ratio of RDF for the CFB boiler to operate stably. With the increasing co-combustion ratio of RDF, the output voltages of electrostatic precipitator (EP), which consists of 2-channels and 5-stages collecting plates, decreased linearly. Eventually, stability of the EP could not be maintained above 5% of the RDF co-combustion ratio. The emissions of NO_x, HCl and dioxin during co-combustion did not change appreciably as compared to the case when Korean anthracite was burnt alone, which were also low enough to meet Korean emissions limits. On the other hand, chlorine contents in ashes emitted from the CFB boiler increased gradually with the increasing co-combustion ratio, which implied that most of chlorines were fixed by limestone.     

富钙生物油的脱硫性能研究

利用自制热重装置分别考察了富钙生物油与传统钙基脱硫剂的性能和温度、CO2,SO2浓度对富钙生物油煅烧产物脱硫性能的影响。试验结果表明,富钙生物油的脱硫速率优于氢氧化钙和乙酸钙。在SO2体积分数低于0.4%时,富钙生物油的脱硫速率在整个脱硫过程中变化很小,由此推断在脱硫过程中其表面以及孔道不会被CaSO4堵塞,整个反应受SO2在其表面的扩散控制。温度对富钙生物油的脱硫性能影响显著,经900℃煅烧,富钙生物油生成的煅烧产物CaCO3/CaO在800～850℃条件下获得最大脱硫速率;CO2的浓度对其脱硫速率无显著影响。烟气中SO2体积分数高于0.4%时,提高SO2浓度会导致富钙生物油脱硫速率增加值显著下降。     

Emissions of gaseous pollutants,polychlorinated dibenzo-p-dioxins,and polychlorinated dibenzo-furans from medical waste combustion in a batch fluidized-bed incinerator

The quantities of pollutants emitted during the incineration of medical waste using a batch fluidized-bed system have not yet been well characterized. In this study, the CO, NO, and SO₂ in the gaseous emissions of a pilot scale vortexing fluidized-bed incinerator (VFBI) and the toxic polychlorinated dibenzo-p-dioxins and polychlorinated dibenzo-furans (PCDD/Fs) in the fly ash collected from the baghouse were examined. Four kinds of simulated medical wastes with different chlorine contents were used. The effects of the feeding interval, chlorine content, and the addition of calcium carbonate were experimentally evaluated. The results showed that increasing the feeding interval decreased the amount of all pollutants due to the decreased bed temperature and prolonged residence time in the incinerator. The addition of calcium carbonate decreased the emissions of the three gaseous pollutants; however, the concentrations of PCDD/Fs of the fly ash increased while calcium carbonate was added. The concentration of NO and SO₂ decreased while CO concentration increased with the increasing of chlorine content in the simulated medical waste. The magnitude of the effects of the operating parameters on the PCDD/F congeners formed followed the order: chlorine content > feeding interval > Ca/Cl ratio. Based on the experimental results, we extrapolate that the threshold value of the chlorine content was about 1% for PCDD/Fs generation. At a lower chlorine content, the PCDDs formation rate is higher than that at a higher chlorine content, especially for 1,2,3,4,6,7,8-HpCDD and OCDD. When the chlorine content exceeds the threshold value of 1%, the formation rate of PCDFs exceeds that of PCDDs.     

Experimental studies on the poisoning properties of a low-plateau hydrogen storage alloy LaNi4.3Al0.7 against CO impurities

Metal hydride (MH) material can be used for effective separation of hydrogen from gas mixture. However, some impurities in the feedstock gas may cause the poisoning of the material and hence failure of the MH-based hydrogen separation system. In this paper, the hydrogen storage alloy LaNi_4.3Al_0.7, which has low-plateau pressure and was supposed to be used for hydrogen separation from the semi-coke oven gas, was tested in the atmosphere with relatively high concentration of CO impurities (～0.1%v/v) by cycling experiments. Interestingly, the hydrogen storage capacity of the material shows quite mild decline during contact with CO at the temperature of 363 K or higher, and relatively fast kinetics can be kept, highlighting its application potential for hydrogen separation on a variety of occasions.     

Yields of pyrolysis products from refuse-derived fuel

Pyrolysis yields and gas characteristics must be studied to control pollution caused by waste-energy recycling and to develop a refuse-derived fuel technology. In this study, refuse-derived fuel pyrolysis experiments were performed in a high-temperature tube furnace. The effects of the final pyrolysis temperature, material mixture ratio, and pyrolysis rate on the yields of pyrolysis products, including gas, tar, and semi-coke, were studied. The volume fractions of the pyrolysis gas components (H₂, CO, CH₄, and CO₂) of the samples were also detected. Results showed that with increased final temperature, the tar and gas yields increased but the semi-coke yield decreased. The volume fractions of the components had the following trends: H₂ increased, CO initially decreased and then increased, CH₄ initially increased and then decreased, and CO₂ decreased. With decreased biomass, the tar yield decreased and then increased, whereas the semi-coke and gas yields increased and then decreased. Compared with slow pyrolysis, fast pyrolysis decreased the tar yield by 9.13%, increased the gas yield by 7.45%, increased the CO and CH₄ volume fractions, and decreased the CO₂ volume fraction.