固态排渣煤粉炉NOx产生浓度影响因素偏相关分析

利用第一次全国污染源普查“火力发电行业产排污系数核算”工作中现场监测得到的数据,首次采用偏相关分析的方法,对固态排渣煤粉炉中机组规模、空气过剩系数、煤中挥发分和发电负荷率等因素对NOx产生浓度的影响进行定性分析,结论：NOx产生浓度与前三种因素存在显著的相关。而与发电负荷率的关系受锅炉是否采用低氮燃烧技术的影响。空气过剩系数越大,煤的挥发分越高,NOx产生浓度越低;采用低氮燃烧装置的锅炉中,机组规模越大,产生的NOx越少,且对于同一锅炉来说,NOx产生浓度随着发电负荷率的升高而增大;未采用燃烧控制的锅炉中,机组规模越大,NOx产生浓度越高,且与发电负荷率不相关。根据分析结果,提出了控制燃煤电厂固态排渣煤粉炉NOx排放的优化措施和建议。     

我国中小型锅炉的NOx排放特征与管理对策

对我国中小型燃煤、燃油、燃气锅炉的NOx排放监测数据进行了统计分析,探讨了NOx的排放特征与管理控制现状.研究结果表明:燃煤锅炉中NOx排放质量浓度小于等于400.00 mg/m3的锅炉占76％,NOx平均排放质量浓度为324.60 mg/m3;燃油锅炉中NOx排放质量浓度小于等于400.00 mg/m3的锅炉占84％...     

西德火电厂烟气脱硫脱氮装置的进展

联邦德国由于森林遭到严重破坏,近年花了大量投资在现有燃煤锅炉上加装控制SO_3和NO_x排放的设备,规模空前,较西欧其他国家领先很多。一、排放控制有关规定., 1.SO~2:排放控制 1983年国家排放控制法(GFAVO)要求容量大于1 10MW的燃煤或燃油机组和电厂(容量总计约50000MW)在1988年7月1日     

ClO_2溶液去除烟气中NO的效果及工程应用

采用实验室规模喷淋脱硝装置对ClO_2溶液去除NO的效果及影响因素进行探讨,通过脱硝产物的测定对ClO_2溶液去除NO的能力及机理进行分析;在此基础上考察ClO_2溶液对供热厂燃煤锅炉烟气的实际脱硝效果。实验结果表明:在液气比为20L/m~3、反应温度为20℃,反应pH为4.0、进气NO质量浓度为250 mg/m~3,ClO_2质量浓度为200 mg/L的条件下,NO去除率达97%以上;ClO_2溶液可将NO氧化吸收为NO_3~-,氧化后产生的NO_x也可被NaOH溶液吸收转化为NO_2~-和NO_3~-;在ClO_2质量浓度为200~500 mg/L,反应pH为5.5~7.0的条件下处理初始NO质量浓度为212~230 mg/m~3的燃煤锅炉烟气,NO去除率为85.7%~94.6%,NO_x去除率为80.4%~88.8%,出口NO_x质量浓度低于46 mg/m~3,远低于GB 13271—2014规定的排放限值。     

国内简讯

采用麻石双冲高效除尘器处理沸腾炉烟尘　　沸腾炉是一种对燃料变化适应性非常强的锅炉 ,沸腾炉内燃料燃烧的特点和层燃炉的燃烧有很大的区别。因为燃料在沸腾炉内停留时间较长 ,着火条件好 ,对灰分大、水分多 ,挥发分少的劣质燃煤也能稳定地燃烧。又由于燃烧方式的不同 ,沸腾炉每平方米火床面积能产生 2 .8～ 3 .3 t/h蒸汽 ,是其他炉型产汽量的 2～ 4倍。甘肃省白银市某公司锅炉房为了节约燃煤费用 ,将 2台 1 0 t/h层燃炉改为沸腾炉后 ,每小时产汽量提高 ,燃料采用劣质煤和层燃炉炉渣 ,节能效果十分显著。但存在的问题是沸腾炉排出的烟气含…     

中储式煤粉锅炉燃烧优化调整试验研究

为提高电厂锅炉燃煤煤质变差后锅炉运行的经济性,进行了燃烧优化调整试验,通过比较飞灰可燃物含量、锅炉热效率、排烟温度、制粉系统耗电率重新确定了制粉系统最佳出力下的经济煤粉细度,分析了制粉系统运行方式、二次风配风方式、过量空气系数、燃煤配比对锅炉运行经济性的影响,提出了锅炉更经济的运行工况。     

燃煤电厂锅炉烟气PM10排放控制技术与应用

介绍了目前中国燃煤电厂锅炉烟气微细粒子的污染状况,提出了对微细粒子排放采用袋式除尘的控制技术,并在河南焦作电厂220 MW机组上成功运行20000 h.实践表明,直通均流式脉冲袋式除尘器可以有效控制燃煤电厂锅炉烟气PM10、PM2.5的排放,满足环保新标准的要求.     

W型无烟煤锅炉氮氧化物排放浓度高的原因分析及解决实例

针对燃煤电厂W型火焰无烟煤锅炉普遍存在的NOx排放浓度高的问题进行了原因分析,与一般燃煤锅炉所排NOx以燃料型为主不同,该锅炉所排NOx的主要类型为热力型,炉膛燃烧温度高是热力型NOx产生量高的主要原因.通过对案例电厂煤质及炉型的分析找到了降低NOx排放的可行方法,对锅炉进行简单改造,掺烧烟煤可显著降低锅炉NOx产生量,通过试验确定掺烧烟煤的合适比例,为类似炉型提供参考.     

“W”火焰超临界锅炉煤质变化时的燃烧调整研究

介绍了2×650 MW超临界机组“W”火焰锅炉燃烧系统组成及特性,指出影响煤粉炉燃烧的主要因素有炉膛温度、煤粉的浓度和细度、燃煤挥发分及燃煤发热量等.分析了燃用煤质偏离设计值时,“W”火焰超临界锅炉燃烧状况,并给出了调整方案.     

基于支持向量机的燃烧过程NOx排放模型

针对电站锅炉煤粉燃烧过程中NOx排放机理模型难以建立的实际情况,取过量空气系数、一次风率、煤粉细度作为输入量,燃烧室NOx排放量作为输出量.建立三个基于向量机的NOx排放模型.研究表明,向量机模型不仅能对训练数据进行很好的训练,而且当预测一种新的工况时,也能对测试数据进行很好的拟合.     

O2/CO2气氛下石灰石煅烧分解的动力学和热力学研究

富氧燃烧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。针对O2／CO2气氛下石灰石煅烧分解特性进行了热力学分析和热重试验结果的动力学分析，将热力学分析结果与热重试验结果进行了对比，得出石灰石的起始分解温度随CO2分压比的增大而增高。     

Co-combustion of agricultural residues with coal in a fluidized bed combustor

Power generation from biomass is an attractive technology that utilizes agricultural residual waste. In order to explain the behavior of biomass-fired fluidized bed incinerator, biomass sources from agricultural residues (rice husk and palm kernel) were co-fired with coal in a 0.15m diameter and 2.3m high fluidized bed combustor. The combustion efficiency and carbon monoxide emissions were studied and compared with those for pure coal combustion. Co-combustion of a mixture of biomass with coal in a fluidized bed combustor designed for coal combustion increased combustion efficiency up to 20% depending upon excess air levels. Observed carbon monoxide levels fluctuated between 200 and 900 ppm with the addition of coal. It is evident from this research that efficient co-firing of biomass with coal can be achieved with minimal modifications to existing coal-fired boilers.     

PHYSICO-CHEMICAL CHARACTERIZATION AND LEACHING OF DESULPHURIZATION COAL FLY ASH

Fly ash produced by coal combustion using two types of desulphurization process were studied: a conventional pulverized coal boiler equipped with lime injection (PCL ash), and a circulating fluidized bed combustion boiler with limestone injection (CFBC ash). The ashes were characterized completely: granulometry, morphology, mineralogy, chemical composition and behaviour to water contact. Both PCL ash and CFBC ash present similar features: fine granulometry, presence of anhydrite phase and sulphate content. However, PCL ash also shows lots of spherical particles, unlike CFBC ash, and a much higher lime content, due to the lower desulphurization rate in PC boilers. Unlike CFBC ash, most of the trace elements in PCL ash show an inverse concentration–particle size dependence. Leachates obtained from both samples are rich in soluble salts [CaSO₄and Ca(OH)₂] and arsenic and selenium are prevented from solubilizing by high lime content. In wetted PCL ash, the formation of ettringite crystals stabilizes calcium and sulphate ions. Simultaneously, arsenate, selenate and chromate anions are trapped in the crystal. CFBC ash does not really harden because the lime content is too low. However, the leached selenium concentration is cut down in wetted CFBC ash samples.     

Numerical simulation of municipal solid waste combustion in a novel two-stage reciprocating incinerator

A mathematical model was presented in this paper for the combustion of municipal solid waste in a novel two-stage reciprocating grate furnace. Numerical simulations were performed to predict the temperature, the flow and the species distributions in the furnace, with practical operational conditions taken into account. The calculated results agree well with the test data, and the burning behavior of municipal solid waste in the novel two-stage reciprocating incinerator can be demonstrated well. The thickness of waste bed, the initial moisture content, the excessive air coefficient and the secondary air are the major factors that influence the combustion process. If the initial moisture content of waste is high, both the heat value of waste and the temperature inside incinerator are low, and less oxygen is necessary for combustion. The air supply rate and the primary air distribution along the grate should be adjusted according to the initial moisture content of the waste. A reasonable bed thickness and an adequate excessive air coefficient can keep a higher temperature, promote the burnout of combustibles, and consequently reduce the emission of dioxin pollutants. When the total air supply is constant, reducing primary air and introducing secondary air properly can enhance turbulence and mixing, prolong the residence time of flue gas, and promote the complete combustion of combustibles. This study provides an important reference for optimizing the design and operation of municipal solid wastes furnace.     

Co-combustion of waste from olive oil production with coal in a fluidised bed

Waste from olive oil production was co-fired with coal in a fluidised bed combustor to study the feasibility of using this waste as an energy source. The combustion efficiency and CO emission were investigated and compared to those of burning 100% of coal. Olive oil waste with up to 20% mass concentration can be co-fired with coal in a fluidised bed combustor designed for coal combustion with a maximum drop of efficiency of 5%. A 10% olive oil waste concentration gave a lower CO emission than 100% coal firing due to improved combustion in the freeboard region. A 20% olive oil waste mixture gave a higher CO emission than both 100% coal firing and 10% olive oil waste mixture, but the combustion efficiency was higher than the 10% olive oil waste mixture due to lower elutriation from the bed.     

Combustion studies of high moisture content waste in a fluidised bed

The combustion of three high moisture content waste materials in a fluidised bed combustor has been investigated and a comparison with co-firing of these materials with coal in the same combustor has been made. Waste materials burnt were olive oil waste, municipal solid waste and potato, which is representative of vegetable waste. Mixtures of up to 20% mass concentration water in the waste were fed to the combustor. Above that value the moisture content was too high to sustain combustion without addition of coal. Measurements of CO, NOx, SO2 temperatures were made and the carbon combustion efficiency evaluated. Co-firing with coal resulted in markedly higher combustion efficiencies with an increase of approximately 10-80% when burning the simulated MSW. However, this was much lower than the value of 93% when coal was burnt on its own. It was also much lower than the value obtained, average 90%, when co-firing potato and olive oil waste with coal and there was little difference in the combustion efficiency between the two types of waste and with increasing moisture content. It was concluded that the high ash content of the simulated MSW 26%, compared with 5% in the other two waste materials resulted in slower burning and consequently the char particles were elutriated from the bed without being fully burnt. In term of gaseous emissions during co-combustion, CO emission is relatively insensitive to change in waste fraction. While emission of SO2 can be reduced as the waste fraction increases as a result of fuel-S dilution. But in terms of percent fuel-S converted, it is actually increased by increasing waste fraction. Emissions of NO and N2O increase slightly with MSW fraction.     

W火焰炉低氮燃烧改造可行性研究

对黔北电厂1～4号W火焰锅炉实际运行状态进行分析,得出NO。排放浓度偏高的主要原因,并提出1—4号机组W火焰炉低氮改造的方案,即在拱下燃烧室内组织大回流长火焰燃烧方式,并通过SOFA风形成炉内深度空气分级低氮燃烧。同时针对1、2号炉和3、4号炉各自特性提出具体的改造方案,保证在锅炉效率不降低的条件下,1～4号W火焰锅炉的NOx排放浓度不高于850mg／m3,从而为W火焰锅炉低氮燃烧改造提供可行性方案,保证W火焰锅炉下一步烟气脱硝的顺利进行。     

循环流化床锅炉采用两级脱硫实现SO_2超低排放的探讨

介绍了循环流化床锅炉炉内脱硫工艺,并以东北某煤矸石电厂为例,对该项目的脱硫方式选择进行了分析,论证了循环流化床锅炉采用两级脱硫方式实现SO2超低排放的合理性和可行性。