中小型燃用烟煤层燃炉NO_x排放特征分析

以86台中小型燃烟煤层燃炉(≤65 MW)的燃料特性分析数据和NOx排放实测数据为基础,通过统计分析方法,研究了锅炉出力、过量空气系数、燃煤挥发分、燃煤氮含量对NOx排放浓度的影响,分析了我国中小型燃烟煤层燃炉NOx的排放与管理控制现状。结果表明,中小型燃用烟煤层燃炉NOx平均排放浓度为324.6 mg/m3;锅炉出力对NOx排放浓度不具有显著影响;燃煤挥发分增高,NOx排放浓度降低;过量空气系数和燃煤氮含量增大,NOx排放浓度增高;并建议在国家层面上尽快制订燃煤锅炉NOx排放标准限值。     

沸腾炉大气污染物初始排放因子的研究

以20台沸腾炉(≤60MW)的燃料特性分析数据和大气污染物的排放实测数据为基础,研究了颗粒物(PM)、SO2和NOX初始排放因子EFP0M、EF0SO2、EF0NOX的变化规律,并利用SPSS13.0统计分析软件,分析了EFP0M、EFS0O2、EF0NOX与影响因子间的相关性。结果表明,在沸腾炉运行负荷≥80%的条件下,EF0PM基本不受锅炉出力(W)、燃煤灰分质量分数(Aar)及过量空气系数(α)的影响,EFP0M与W、Aar、α不具有相关性;EF0SO2主要受燃煤硫质量分数(Sar)的影响,两者具有显著正相关关系;W、α、燃煤干燥基挥发分质量分数(Vdaf)对EF0NOX具有显著影响,EF0NOX与α具有显著正相关关系,而EF0NOX与W、Vdaf具有显著负相关关系;EFS0O2和EF0NOX影响因子由强到弱的顺序为:①EFS0O2:SarαW;②EF0NOX:VdafαW燃煤氮质量分数(Nar)。     

锅炉烟尘排放浓度测试中的过量空气系数

测定锅炉烟尘排放浓度，必须要考虑过量空气系数，因其对锅炉烟尘排放浓度测定值的影响不可忽略。     

中国山东电网燃煤锅炉NOx排放状况和治理技术试验研究

通过对山东电网所属发电厂锅炉NOx排放状况进行调查、测试,得出锅炉NOx排放量与煤种、炉型、燃烧器型式、运行中空气过剩系数、负荷等的关系.结果表明,山东省火力发电厂50 MW及以上容量机组2003年的NOx排放总量超过40万t(按NO2计算).控制和治理NOx排放已成为刻不容缓的重要工作.     

秸秆成型燃料锅炉污染物排放规律试验研究

根据锅炉烟尘测试方法(GB 5468-91)及锅炉大气污染物排放标准(GB 13271-2001),在不同风门的工况下,分别对设计的双层炉排秸秆成型燃料锅炉污染物排放规律进行试验.试验表明,在较好工况下,双层炉排锅炉排烟中CO等中间产物及烟尘含量低于单层炉排锅炉,其排烟中CO、NOx、SO2和烟尘浓度等指标远远低于燃煤锅炉,符合国家关于工业锅炉大气污染物排放标准要求,有较好环保效益.     

我国氮氧化物排放因子的修正和排放量计算:2000年

根据我国城市的发展状况 ,采用城市分类的方法 ,将我国 2 6 1个地级市按照人口数量分为 5个类别。每类城市选取一个典型城市进行实地调查 ,对我国燃烧锅炉和机动车的NOx 的排放因子进行了修正 ,提出了适合我国目前排放水平的各类城市的固定源和移动源的排放因子。并依据 2 0 0 0年中国大陆地区的电站锅炉、工业锅炉和民用炉具的燃料消耗量和机动车保有量 ,以地级市为基本单位 ,估算了 2 0 0 0年我国各地区的NOx 排放量 ,分析了分地区、分行业、分燃料类型的NOx 排放特征。 2 0 0 0年我国NOx 排放总量为 11.12Mt,其中固定源占 6 0 .8% ;移动源占 39.2 %。NOx 排放在地域、行业和燃料类型上分布均不平衡。NOx 的排放主要集中在华东和华北地区 ,其排放量占全国排放量的一半以上。燃煤为最重要的NOx 排放源 ,其排放量占燃料型NOx 排放量的 72 .3%左右。     

垃圾分类背景下厨余垃圾剔除比例对生活垃圾焚烧厂NOx排放的影响

收集了生活垃圾焚烧厂关停SNCR时燃料的N排放数据以及与之对应的工况和燃料特性数据,并分析各影响因素对燃料N转化过程中不同环节的影响机理.结果表明,在工业化生产中,燃料N转化率与炉温、垃圾含水率之间不存在显著联系,而随N元素含量和固定碳含量的增加而降低,随过剩空气系数、H/N、O/N的增加而升高.据此提出了符合实际生产条件的燃料N转化路径图.该路径图表明,燃料特性对燃料N转化率和NOx生成浓度起到了决定性作用,并进一步量化了H/N和固定碳含量这2个参数与燃料N转化率之间的关系.提出通过将厨余垃圾从生活垃圾分出的方法来减少NOx生成,并以国内典型城市为例,研究了分出不同比例厨余垃圾的情况下,燃料N转化率和NOx生成浓度的变化趋势.本研究表明通过分出厨余垃圾的方法,能够降低垃圾焚烧厂的脱硝成本及氨逃逸风险,可为进一步控制生活垃圾焚烧过程中的NOx排放提供参考.     

小型燃油锅炉大气污染物的排放管理控制

燃料燃烧过程是大气污染物的重要来源之一,对人体健康,空气质量和气候变化具有非常重要的影响;管理控制是控制污染物排放的重要手段.以85台小型燃油锅炉(≤10.5 MW)燃料特性分析数据和污染物排放实测数据为基础,通过统计分析方法,分析了中国在用燃油品质以及大气污染物的排放现状,讨论了小型燃油锅炉大气污染物排放管理控制的潜力与可行性.结果表明,对燃油品质的管理控制是有效控制燃烧过程大气污染物排放的重要措施,分别有95%和98%燃油的灰分和含硫量符合国家相关规定;所有测试锅炉PM排放浓度远低于<锅炉大气污染物排放标准>(GB/T 13271-2001)规定的最高允许排放限值,有90%以上的锅炉达到GB/T 13271～2001中SO2最高允许排放限值,有84%的锅炉达到GB/T 13271-2001中NOx最高允许排放限值;与其他国家相比,中国对小型燃油锅炉常规大气污染物排放的管理控制处于中等水平,应当适时开展对有害空气污染物的管理控制.     

小型燃油锅炉NOx的排放特征与管理控制

以68台燃油锅炉（≤10～MW）NOx排放实测数据为基础，通过统计分析方法，研究了NOx的排放特征；通过对比分析，探讨了我国燃油锅炉NOx排放控制与管理现状，讨论了进一步加强我国燃油锅炉NOx排放管理控制的可能性与可行性，并提出了相应的管理控制建议。结果表明，NOx平均排放浓度为318．2mg／m^3，基于燃料消耗量的平均排放因子为4．4kg／t，基于燃料发热量的平均排放因子为102．8ng／J，基于燃料氮含量的平均排放因子为2．1mg／mg；建议采取分阶段控制的方式，逐步提高NOx排放限制，从而实现控源减排目标。     

切圆燃烧煤粉炉的空气分级燃烧改造

阐述了分级燃烧抑制NOx形成的基本原理,介绍了切圆燃烧煤粉炉的空气分级燃烧改造的基本特点,考察了轴向和径向空气分级、炉内空气浓度等因素对NOx排放量的影响;控制适当条件,使脱氮效率达到30％－50％,对煤粉炉的空气分级燃烧改造进行了费用效益分析。     

Problems of Meeting Multiple Air Quality Objectives for Coal-Fired Utility Boilers

Gaseous wastes and particulate emissions are produced in the process of burning coal to produce electrical energy. In attempting to control these gaseous wastes, changes in the operation efficiency of boilers and secondary equipment are likely to result, and in addition liquid and solid waste streams are produced. The interrelationships among the various forms of wastes and the effects of air quality control on process efficiency are often overlooked in studies of environmental quality management.

The study was undertaken to evaluate the technical alternatives for handling gaseous and particulate emissions from coal-fired boilers and to determine the feasibility of meeting several standards simultaneously. The gaseous emissions of major importance in the combustion of coal are parti culates, oxides of sulfur, and oxides of nitrogen. Particulates can be controlled by a tradeoff among further preparation at the mine (for additional ash removal), type of boiler, use of dust control equipment and high stacks for dispersion of residual emissions, if ambient air standards are considered. Oxides of sulfur reduction depends currently on fuel substitution, limestone additives in the boiler and some form of contact process such as wet scrubbing, or the use of high stacks. Oxides of nitrogen control in coal fired boilers is restricted to small reductions by either changes in boiler operation, such as lower excess air levels, adsorption during wet scrubbing or by dispersion from high stacks.     

Emissions of sulfur trioxide from coal-fired power plants

Emissions of sulfur trioxide (SO3) are a key component of plume opacity and acid deposition. Consequently, these emissions need to be low enough to not cause opacity violations and acid deposition. Generally, a small fraction of sulfur (S) in coal is converted to SO3 in coal-fired combustion devices such as electric utility boilers. The emissions of SO3 from such a boiler depend on coal S content, combustion conditions, flue gas characteristics, and air pollution devices being used. It is well known that the catalyst used in the selective catalytic reduction (SCR) technology for nitrogen oxides control oxidizes a small fraction of sulfur dioxide in the flue gas to SO3. The extent of this oxidation depends on the catalyst formulation and SCR operating conditions. Gas-phase SO3 and sulfuric acid, on being quenched in plant equipment (e.g., air preheater and wet scrubber), result in fine acidic mist, which can cause increased plume opacity and undesirable emissions. Recently, such effects have been observed at plants firing high-S coal and equipped with SCR systems and wet scrubbers. This paper investigates the factors that affect acidic mist production in coal-fired electric utility boilers and discusses approaches for mitigating emission of this mist.     

Emissions of Sulfur Trioxide from Coal-Fired Power Plants

Abstract

Emissions of sulfur trioxide (SO₃) are a key component of plume opacity and acid deposition. Consequently, these emissions need to be low enough to not cause opacity violations and acid deposition. Generally, a small fraction of sulfur (S) in coal is converted to SO₃ in coal-fired combustion devices such as electric utility boilers. The emissions of SO₃ from such a boiler depend on coal S content, combustion conditions, flue gas characteristics, and air pollution devices being used. It is well known that the catalyst used in the selective catalytic reduction (SCR) technology for nitrogen oxides control oxidizes a small fraction of sulfur dioxide in the flue gas to SO₃. The extent of this oxidation depends on the catalyst formulation and SCR operating conditions. Gas-phase SO₃ and sulfuric acid, on being quenched in plant equipment (e.g., air preheater and wet scrubber), result in fine acidic mist, which can cause increased plume opacity and undesirable emissions. Recently, such effects have been observed at plants firing high-S coal and equipped with SCR systems and wet scrubbers. This paper investigates the factors that affect acidic mist production in coal-fired electric utility boilers and discusses approaches for mitigating emission of this mist.     

燃煤工业锅炉排放二氧化硫对大气的污染及工业固硫型煤的应用

本文论述了我国燃煤工业锅炉排放ＳＯ２对大气污染的状况及发展趋势,以及应用工业固硫型煤控制燃煤工业锅炉对大气的污染。燃煤工业锅炉燃烧工业固硫型煤时,可明显地降低ＳＯ２和烟尘的排放量,并节约煤炭。在当前及今后相当长的时期内,推广和发展工业固硫型煤,是防治燃煤工业锅炉大气ＳＯ２污染的一条投资少、见效快、简便易行的实用措施,其经济效益及环境效益相当可观。     

燃油锅炉燃烧过程SO2的生成与排放特征

燃料燃烧过程是大气污染物的重要来源之一，对人体健康、空气质量和气候变化产生非常重要的影响。以62台燃油锅炉（≤10.5 MW）的燃料特性分析数据和SO₂排放实测数据为基础，通过统计分析方法，研究了燃油燃烧过程中燃油硫含量S和过量空气系数α对硫的转化率、SO₂排放因子和排放浓度的影响，获得了基于燃料消耗量、燃料发热量的SO₂排放因子EF_C、EF_H以及SO₂标态折算浓度C′_SO2与硫含量S间的关联式。结果表明，在过量空气系数α＞1的燃油燃烧过程中，EF_C、EF_H、C′_SO2与燃油硫含量S呈现出显著的线性正相关性，而与过量空气系数α无关，其关系式分别为：EF_C=18.86602×S，EF_H=443.78751×S ，C′_SO2＝1 509.28337×S；硫转化率η和基于燃料硫含量的SO₂排放因子EF_S则与燃油硫含量S和过量空气系数α无关，其平均值分别为96.3％和1.93 kg/kg。     

Nitrogen oxides emission control options for coal-fired electric utility boilers

Recent regulations have required reductions in emissions of nitrogen oxides (NOx) from electric utility boilers. To comply with these regulatory requirements, it is increasingly important to implement state-of-the-art NOx control technologies on coal-fired utility boilers. This paper reviews NOx control options for these boilers. It discusses the established commercial primary and secondary control technologies and examines what is being done to use them more effectively. Furthermore, the paper discusses recent developments in NOx controls. The popular primary control technologies in use in the United States are low-NOx burners and overfire air. Data reflect that average NOx reductions for specific primary controls have ranged from 35% to 63% from 1995 emissions levels. The secondary NOx control technologies applied on U.S. coal-fired utility boilers include reburning, selective noncatalytic reduction (SNCR), and selective catalytic reduction (SCR). Thirty-six U.S. coal-fired utility boilers have installed SNCR, and reported NOx reductions achieved at these applications ranged from 15% to 66%. Recently, SCR has been installed at >150 U.S. coal-fired utility boilers. Data on the performance of 20 SCR systems operating in the United States with low-NOx emissions reflect that in 2003, these units achieved NOx emission rates between 0.04 and 0.07 lb/10(6) Btu.