六角切圆锅炉改造后NOx排放特性研究

为了研究六角切圆煤粉锅炉在超低排放改造后脱硝进出口NO_x的分布及出口逃逸氨浓度的特点,进行了现场试验测试。结果发现,脱硝系统的入口NO_x分布不均匀、喷氨量不均匀是导致出口NO_x分布不均匀、氨逃逸质量浓度超过设计值的主要原因,机组需要进行喷氨优化调整。     

面向灵活性发电的燃煤机组大气排放特性分析

随着可再生能源发电在电网中占比逐年增加,越来越多的燃煤机组参与灵活性发电。为了弄清灵活性发电燃煤机组的大气排放特性,以某亚临界600 MW和300 MW机组为例,通过对运行数据进行回归分析,获得了机组在启动、正常调峰和深度调峰阶段的CO₂、NO_x、SO₂和粉尘的排放特性。结果表明：正常调峰阶段,随着机组负荷下降,煤耗和CO₂排放因子逐渐增大,净烟气NO_x排放因子先减小后增大,SO₂排放因子略有下降;粉尘排放因子略有上升;深度调峰阶段,随机组负荷的进一步降低煤耗和CO₂排放因子明显增大,净烟气NO_x和粉尘排放因子迅速增大,SO₂排放因子继续下降;启动过程净烟气NO_x和粉尘排放因子明显高于调峰工况,SO₂排放因子略小于调峰工况。另外,调峰过程中较高的升降负荷率使得原烟气NO_x、SO₂排放因子明显增大,净烟气粉尘排放因子明显增大。     

燃煤电厂烟道结构参数测量方法的研究

燃煤电厂温室气体排放量是环保部门核查监测的重要指标。温室气体排放量实测法是通过测量固定排放源的温室气体流量与浓度,计算出某种温室气体排放量的方法。固定排放源的流量测量主要使用速度面积法。但是对于建造年代久远,且设计图纸已经缺失的烟道或烟囱,如何获得测量烟道的结构参数成为流量测量的关键。文章提出了两种烟道结构参数的测量方法。全站仪测量法通过在烟道附近布站,可以获得被测烟道的外部结构参数,结合烟道壁厚数据,计算出内部结构参数。对于预留人口,测量人员可以进入的烟道,也可以选择三维激光扫描仪进行测绘,通过靶球辅助,直接获得烟道内部三维结构模型。课题组应用上述两种方法对河南某燃煤电厂烟道进行测量,两种方法比对复现性较好,并结合测得的结构参数绘制了烟道的三位结构模型。     

基于遗传算法优化BP神经网络的SCR脱硝系统催化剂体积设计

火电厂SCR脱硝系统的设计需要在满足脱硝效率的同时,尽可能节约成本,因此需要准确预测SCR脱硝所需的催化剂体积。火电厂的烟气条件复杂多变,烟气温度、烟气流量、出入口NO_x浓度等参数都会影响SCR催化剂的体积设计,因此催化剂体积预测是一个多因素耦合的问题。针对这一特点,使用BP神经网络对催化剂体积设计进行了预测,并针对该模型结构上的缺陷,进行基于遗传算法优化的神经网络建模研究。结果表明,遗传算法优化后的BP神经网络模型预测精度和数据拟合能力均有提高,为脱硝系统的催化剂体积设计提供了新思路。     

楼宇型燃气分布式能源系统SCR脱硝应用研究

能源与环境的矛盾不断深化,能源行业正从传统能源向清洁能源方向转变,因此高效低碳的燃气分布式能源（natural gas distributed energy,NGDE）将受到越来越多的重视;但是随着国家环保要求不断提高,以内燃机为主的楼宇型NGDE项目的脱硝改造势在必行。以某楼宇型NGDE项目为研究对象,分析研究选择性催化还原法（selective catalytic reduction,SCR）脱硝工艺在分布式能源项目应用的可能性;最后项目在小型MW级的NGDE系统得到成功应用,脱硝效率达到95%以上,NO_x的排放值为25.4 mg/m³,烟气脱硝指标达到北京市固定式内燃机大气污染物排放标准,脱硝效果良好,为分布式能源项目脱硝提供了全新的解决方案。     

NH3对SCR催化剂Hg0催化氧化性能的影响

作为我国主要的汞污染源之一,燃煤电厂汞污染物排放控制是我国环保标准的要求。通过改性SCR催化剂和卤化物添加等方法将Hg⁰氧化为Hg²⁺,进而通过后续设备进行脱除,是提高汞脱除率的有效方法。但对我国而言,这类结合现有环保设备的联合脱除方法都面临着SCR入口高浓度NH₃的抑制作用。为此,基于文献调研,总结了NH₃对SCR催化剂Hg⁰氧化性能的影响,以及卤素存在条件下NH₃对Hg⁰氧化性能的影响,分析了改性催化剂及卤化物添加对Hg⁰氧化率的提高机理,进而对应地分析了NH₃对Hg⁰氧化的抑制机理。研究结果为实际燃煤电厂提高SCR设备Hg⁰氧化率提供了参考。     

燃煤电厂“超净排放”——湿式除尘器

"超低排放"是燃煤电厂当前改造的首要任务,烟囱出口含尘量实现2014年7月1日实施的《火电厂大气污染物排放标准》要求的燃气轮机排放标准。即满足烟尘排放浓度≤5mg/m3。目前已运行的燃煤机组的烟尘处理均采用静电除尘器、电袋除尘器或布袋除尘器,处理全烟气量时的烟囱出口烟尘排放浓度为20mg/m3~30mg/m3;脱硫采用石灰石-石膏湿法脱硫工艺系统或海水脱硫系统;保证在锅炉BMCR工况下脱硫效率不小于95%。如实现烟囱出口烟尘排放浓度≤5mg/m3首选湿式电尘器。     

燃煤电厂超低排放湿法脱硫治霾影响分析

根据燃煤电厂湿法脱硫出口污染物排放浓度及其排放绩效,分析了超低排放湿法脱硫的治霾效果,阐明了湿法脱硫有利于减少SO₂、颗粒物、SO₃的排放量,这些污染物都是形成雾霾的前体物,表明超低排放湿法脱硫对雾霾治理有积极的贡献。同时,烟气超低排放具有协同治理有色烟羽的能力,对于有色烟羽治理应采取因地制宜的策略。煤电行业广泛开展烟气超低排放改造后,大气污染物排放量持续减少,空气环境质量逐年改善,湿法脱硫、烟气超低排放功不可没。     

耐火砖-钢烟道及其阀部件不停产并网施工改进措施

某焦炉检修项目原烟囱烟气装置上为达标排放增加了烟气脱硫脱硝处理装置,把原耐火砖烟道内的烟气用钢烟道接驳引至新增装置处理后再返回耐火砖烟道,通过烟囱排放.在改造施工的过程中,本文针对施工重点难点问题,在不停产条件下,通过对原设计施工方法进行改进,采用弧形钢模板、闸板阀快装底座等技术措施,高效、安全地完成了施工.其改进措施可为同类工程提供参考.     

基于声源监测的厂界噪声预测及贡献分析方法研究

噪声监测是环境噪声预测和治理的重要技术方法。提出了一种基于声强测量的声源监测方法并应用于电厂环境噪声预测和厂界噪声贡献分析。在电厂主要设备噪声源附近布置测点测量并计算设备厂房的辐射声强，将设备厂房简化为面声源建立噪声预测模型，并以测量计算的声强级作为声源模型的源强。利用该模型计算厂界预测点A声级，与实验值具有良好的一致性，验证了该声源监测方法数据的可靠性与噪声预测模型的正确性。通过该模型计算分析了电厂主要噪声源对厂界噪声排放的贡献和影响，为电厂噪声治理提供技术依据。     

Analysis of Flue Gas Pollutants Deep-removal Technology in Coal-fired Power Plants

In recent years, frequent haze has made PM_2.5 become a public hotspot. PM_2.5 control has been added to the 2012 release “ambient air quality standard.” Currently flue gas pollutant control technology does not easily remove PM_2.5. Developing Flue Gas Pollutant Deep-removal Technology (DRT) for coal-fired power plants for deep-removing pollutants such as PM_2.5, SO₂, SO₃, and heavy metals, is an urgent problem. Based on the analysis of the necessity and existing problems of developing DRT suitable for China, this study focused on PM_2.5 removal technology, low NO_x emission of ultra supercritical boiler under all load conditions, and the adaptability of SCR working temperature. Finally, the flue gas pollutant removal system at a 2×660MW supercritical power plant was introduced, and the roadmap for developing DRT for 1,000MW ultra supercritical units was analyzed.     

Removal of NO from flue gas by aqueous chlorine-dioxide scrubbing solution in a lab-scale bubbling reactor

The present study attempts to clean up nitric oxide from the simulated flue gas using aqueous chlorine-dioxide solution in the bubbling reactor. Chlorine-dioxide is generated by chloride–chlorate process. Experiments are carried out to examine the effect of various operating variables like input NO concentration, presence of SO₂, pH of the solution and NaCl feeding rate on the NO_x removal efficiency at 45 °C. Complete oxidation of nitric oxide into nitrogen dioxide occurred on passing sufficient ClO₂ gas into the scrubbing solution. NO is finally converted into nitrate and ClO₂ is reduced into chloride ions. A plausible reaction mechanism concerning NO_x removal by ClO₂ is suggested. DeNO_x efficiency increased slightly with the increasing input NO concentration. The presence of SO₂ improved the NO₂ absorption but pH of solution showed marginal effect on NO₂ absorption. NO_x removal mechanism changed when medium of solution changed from acidic to alkaline. A constant NO_x removal efficiency of about 60% has been achieved in the wide pH range of 3–11 under optimized conditions.     

电厂锅炉优化改造试验分析

为进一步提高锅炉效率,减少锅炉污染物排放,以某电厂锅炉为研究对象,对锅炉的空预器密封装置、水平烟道吹灰系统以及高压省煤器进行等进行整体优化,对锅炉进行化学清洗和保温处理,通过试验对优化前后对锅炉热效率及污染物排放进行对比。结果表明：与改造前相比,不同负荷下锅炉效率平均提高2.3%,同时供电煤耗降低;锅炉排烟温度降低,干烟气热损失减少;未燃尽率碳热损失及空预器漏风率也大幅降低,锅炉排放NOx浓度达到排放要求。此次优化改造达到了预期效果。     

The preparation and gas sensitivity study of polythiophene/SnO2 composites

Nanocomposites of SnO₂ and polythiophene (PTP) were synthesized by the in situ chemical oxidative polymerization method. These nanocomposites were characterized by FTIR, transmission electron microscope (TEM), X-ray diffraction (XRD) and thermogravimetric and differential thermal analysis (TG–DTA) techniques, which proved the polymerization of thiophene monomer and the strong interaction between polythiophene and SnO₂. The composites were used for gas sensing to methanol (MeOH), ethanol (EtOH), acetone, and NO_x at different working temperature. It was found that PTP/SnO₂ materials with different PTP mass percent (1%, 5%, 10%, 20% and 30%) could detect NO_x with very higher selectivity and sensitivity at much lower working temperature than the reported SnO₂. The PTP/SnO₂ nanocomposites responded to NO_x at concentration as low as 10 ppm. PTP/SnO₂ composite containing 5 mass% PTP showed the highest sensitivity at room temperature. The sensing mechanism of PTP/SnO₂ nanocomposites to NO_x was presumed to be the effects of p–n heterojunction between PTP and SnO₂.     

330 MW燃煤火电机组脱硝系统的优化研究

目前国内火电厂选择性催化还原法（selective catalytic reduction,SCR）烟气脱硝系统由于普遍存在反应时间较长、控制滞后和调门线性不好等缺点,SCR出口氮氧化物浓度大幅波动,严重影响火电厂SCR烟气脱硝系统的达标运行。为解决上述问题,根据电厂SCR脱硝系统的运行状况,在研究现场工程实际控制系统的基础上,结合相关SCR脱硝系统控制理论,通过采集现场历史数据,在保持现场实际控制算法不变的基础上,采用智能辨识的方法,建立了SCR脱硝系统数学模型,并采用工程性强的仿人智能算法,实现了SCR脱硝系统的优化运行。     

Removal of SO2 and NO from flue gas by wet scrubbing using an aqueous NaClO2 solution

This study used a NaClO₂/NaOH solution as the additive/absorbent to determine the extent of NO_x removal in a wet scrubbing system. A combined SO_x/NO_x removal system was also tested. The experiments were performed in a bench-scale spraying sieve tray wet scrubber in a continuous mode. The operating variables included NO and SO₂ concentrations, L/G ratio, molar ratio, and initial pH.

The results of the individual DeNO_x experiments show that the maximum DeNO_x efficiencies ranged from 3.1 to 12.6%. The results of the combined DeSO_x/DeNO_x experiments show that the maximum DeNO_x and DeSO_x efficiencies ranged from 36.6 to 71.9% and from 89.4 to 100.0%, respectively. The major parameters affecting NO_x removal efficiencies are the L/G ratio and the dosage of additive. The major parameter influencing DeSO_x efficiencies is the L/G ratio.