新型催化剂MOFs在低温还原脱硝以及吸附VOCs领域的应用

随着我国对于VOCs和NOx污染的治理进入攻坚阶段,异相催化领域的高效多孔催化剂材料MOFs应用于VOCs和NOx污染的治理被逐渐重视起来。良好的吸附性能和高度的反应活性为MOFs应用于VOCs治理、烟气SCR脱硝工艺的核心因素。本文主要探索和总结MOFs高效吸附性能和高度活化性能以及应用于VOCs和NOx治理领域的前景。     

炼化企业NO_x排放及防治技术研究进展

大气中的NOx是PM2.5的重要组成成份,近几年来雾霾天气接连不断,引起了人们对NOx的治理工作的极大重视。而炼化企业作为我国清洁能源的最大供应商,也是NOx排放的一大主要贡献源,因此对其NOx的排放治理自然不可忽视。本文在查阅文献的基础上,对目前国内炼化企业使用到的主要脱硝技术进行了简单介绍和总结。     

硝酸尾气源头治理的原理与方法

从硝酸生产的基本原理出发,并结合实际探讨了源头治理硝酸生产尾气中NOx的方法。该方法不仅符合清洁生产机制,而且从源头治理后且未经后期处理的尾气中的NOx体积分数可达到50×10-6以下,治理效果明显。     

催化剂生产中NO_x废气治理技术影响因素分析

介绍了FYHG-DN技术治理NOx废气的原理和技术特点,分析了催化剂生产过程中含NOx废气排放特点和影响FYHG-DN氮氧化物治理装置处理效果的因素,并对各因素提出有针对性的措施,以保证更好的处理效果,满足长周期稳定运转的生产需求。     

国外NOx废气治理烧后控制技术进展

介绍了近年来国外NOx 废气治理方法烧后控制技术研究情况。作为吸收剂 ,被研究的有二硫化钠溶液和亚砷酸钠溶液 ;作为吸附剂—催化剂 ,被研究的有Na/γ -Al2 O3;介绍了烧后控制NOx 方法和经济型NOx 控制法 (双催化剂法 )。     

熟料煅烧过程的NO_x成因与生产控制

装置低氮燃烧器与燃煤添加剂技术降低NOx排放属于前期控制,能够显著降低NOx的生成量。在水泥窑安装脱硝装置之前,根据企业实际生产状况,从生产源头抓起,对NOx排放量进行测定。并结合自身实际,针对生产过程各阶段导致NOx生成的不同因素,有的放矢地采取相应对策,确定合理的降NOx措施。事先把关控制,会有效降低NOx的产生,减轻后期处理负荷,减少脱硝投资和生产成本。比仅靠后期减排治理,会取得事半功倍的效果。     

稀释剂对氮氧化物生成的影响

通过对稀释剂在NOx治理方面的作用展开了简要的分析和评价。分析表明,氧浓度越高,CO2稀释效果越明显,NOx浓度越低;N2稀释燃料火焰质量流量的效果比稀释空气对降低NOx浓度更加有效。CO2和N2两者不论是空气还是燃料稀释,都会减少NOx的稀释量,在同一速度下,稀释空气比稀释燃料对NOx降低更有效。不过,稀释浓度的增加会导致温度的下降。而SO2在贫燃料状态下,N/S中的S越大,NOx生成越小;在富燃料状态下,S越大NOx生成越大。     

减少柴油机排气污染的化学方法

柴油机、汽油机燃烧过程排放物主要有CO、HC、NOx、SOx及粒子等 ,而柴油机排气中的有害物远低于汽油机 ,但高于汽油机加三元催化剂体系。本文重点介绍了柴油机排气中NOx和粒子的治理方法     

硝酸尾气NOx治理技术综述

综述了目前国内外硝酸尾气NOx治理技术的进展情况,对各种治理方法的原理进行了阐述,同时对其优缺点进行了简要分析和比较。     

辊道窑烧制陶瓷过程中NO_x的排放分析及治理

针对陶瓷行业NOx排放问题,笔者选取了作为"陶都"的佛山市对其能耗、数量较大的辊道窑进行测试及分析,得出NOx的排放数据,进而分析及提出治理方法。分析得出生产同产品的辊道窑燃用天然气较燃用其他燃料生成的NOx低,选用天然气作为燃料有利于降低NOx排放。     

护理干预对住院糖尿病患者便秘影响的探讨

目的探讨护理干预对住院糖尿病患者便秘的影响。方法将102例糖尿病便秘者随机分为干预及对照组,干预组给予腹部按摩、健康教育等护理干预措施,对照组给予通便药物治疗,比较2组通便效果及不良反应。结果干预组和对照组有效率分别为75%、88%,P>0.05(u=1.686),差异无显著性。意义:对照组腹痛腹泻、反复便结应发生率高于干预组,差异有显著性意见P>0.01(χ2=29.678,8.575)。结论通过护理干预改善住院糖尿病患者便秘效果较好,且不良反应低。     

A deep graph convolutional network model of NOx emission prediction for coal-fired boiler

To deal with environmental problems caused by NOx production in thermal plants, it is imperative to establish a reliable model to predict NOx concentration in the combustion process. NOx formation in a coal-fired boiler is complex, and many variables affect NOx emissions. The effective information fusion of these variables can improve the accuracy of NOx concentration prediction. However, the existing NOx prediction algorithms based on thermal parameters rarely consider the mechanical knowledge of the boiler operation, and it is not easy to incorporate the topological information of production into modelling. Therefore, a graph convolutional network is proposed for NOx emission prediction. First, the key variables affecting NOx generation are selected according to the knowledge and the random forest-based variable importance. Then, the model structure is designed by exploring the topological information among thermal variables to capture the complex spatial dependence. The model inputs are constructed by coding different operation variables, and the adjacency matrix is generated according to the correlation information between variables, which can fuse data information and reduce redundancy. On this basis, the prediction model of NOx concentration is established. Historical data from a 660 MW coal-fired boiler are used in the experiment. The prediction results show that the proposed model can effectively fuse the information of characteristic variables and fully exploit the non-linear mapping relationship between process variables and NOx emission. When compared with three typical models in NOx modelling, the proposed model has better performance with a determination coefficient of 0.906.     

概述氮氧化物的催化脱除技术

催化脱硝是催化研究领域中很重要的一部分。介绍了催化脱除氮氧化物(NOx)的几种方法:NOx直接催化分解法、NOx储存还原法(NSR)以及使用不同还原剂(碳烟尘、烃(HC))的选择性催化还原法(SCR)。讨论了NSR的反应原理和载体、贵金属、储存材料、SO2、H2O以及反应条件对整个催化作用的影响,同时论述了HC-SCR的两种反应机理,在机理讨论的基础上还分析了一些对HC-SCR反应活性有影响的因素:催化剂载体、金属负载量、焙烧温度、催化剂预处理方法、O2、还原剂、H2O和SO2。     

降低NOX污染的净化处理法

燃烧等带来的ＮＯＸ是酸雨的主要来源。高温催化燃烧可抑制ＮＯＸ的生成；选择催化 法（ＳＣＲ）为消除ＮＯＸ的成熟技术，是处理煤电厂烟道气的必要措施；烟道气循环法和低ＮＯＸ燃烧器法简单实用；在氧气存在下烃类化合物对ＮＯＸ还原法较符合工业尾气的实际条件，因而是个活跃的研究领域。     

Overview of the Fundamental Reactions and Degradation Mechanisms of NOx Storage/Reduction Catalysts

Over the last several years, nitrogen oxide(s) (NOx) storage/reduction (NSR) catalysts, also referred to as NOx adsorbers or lean NOx traps, have been developed as an aftertreatment technology to reduce NOx emissions from lean-burn power sources. NSR operation is cyclic: during the lean part of the cycle, NOx are trapped on the catalyst; intermittent rich excursions are used to reduce the NOx to N₂ and restore the original catalyst surface; and lean operation then resumes. This review will describe the work carried out in characterizing, developing, and understanding this catalyst technology for application in mobile exhaust-gas aftertreatment. The discussion will first encompass the reaction process fundamentals, which include five general steps involved in NOx reduction to N₂ on NSR catalysts; NO oxidation, NO₂ and NO sorption leading to nitrite and nitrate species, reductant evolution, NOx release, and finally NOx reduction to N₂. Major unresolved issues and questions are listed at the end of each of the reaction process fundamental sections. Degradation mechanisms and their effects on NSR catalyst performance are also described in relation to these generalized reactions. Since at this stage it does not appear possible to arrive at a complete and consistent mechanistic model describing the broad, existing experimental phenomenology for these processes, this review is primarily focused on summarizing and evaluating literature data and reconciling the many differences presented.     

浅谈降低300MW锅炉NOX排放的措施

分析了我国300MW锅炉NOX排放的现状。介绍黔北发电厂300MW东方锅炉在技术改造、操作调整等方面降低NOX排放的措施,减少300MW锅炉的NOX排放。     

玉环电厂降低NOx的排放措施

介绍了玉环电厂降低NOx排放的技术措施：PM型低NOx燃烧器、MACT燃烧系统以及SCR尾部烟气脱硝技术。玉环电厂的NOx排放量符合国际规定的最低标准,SCR烟气脱硝装置的投运,进一步减少了NOx的排放量,为中国百万机组烟气脱硝技术改造提供宝贵的经验和数据,同时也为SCR烟气脱硝技术的产业化奠定了基础。     

Bioprocesses for the removal of nitrogen oxides from polluted air

Nitrogen oxides (NOx) of environmental concern are nitrogen monoxide (NO) and nitrogen dioxide (NO₂). They are hazardous air pollutants that lead to the formation of acid rain and tropospheric ozone. Both pollutants are usually present simultaneously and are, therefore, called NOx. Another compound is N₂O which is found in the stratosphere where it plays a role in the greenhouse effect. Concern for environmental and health issues coupled with stringent NOx emission standards generates a need for the development of efficient low‐cost NOx abatement technologies. Under such circumstances, it becomes mandatory for each NOx‐emitting industry or facility to opt for proper NOx control measures. Several techniques are available to control NOx emissions: selective catalytic reduction (SCR), selective non‐catalytic reduction (SNCR), adsorption, scrubbing, and biological methods. Each process offers specific advantages and limitations. Since bioprocesses present many advantages over conventional technologies for flue gas cleaning, a lot of interest has recently been shown for these processes. This article reviews the major characteristics of conventional non‐biological technologies and recent advances in the biological removal of NOx from flue gases based on the catalytic activity of either eucaryotes or procaryotes, ie nitrification, denitrification, the use of microalgae, and a combined physicochemical and biological process (BioDeNOx). Relatively uncomplicated design and simple operation and maintenance requirements make biological removal a good option for the control of NOx emissions in stationary sources. Copyright © 2005 Society of Chemical Industry     

煤燃烧中影响NOx生成因素的分析

概述了煤燃烧中空气分级燃烧技术,分析了NOx生成的影响因素。影响NOx形成的主要锅炉操作参数为:初级燃烧区化学计量比为0.7～0.9,停留时间较长时,NOx的生成量较少;温度的影响与环境的氧化/还原气氛有关;增加过量空气,NOx生成量增加。影响NOx生成的最主要的煤性质是氮含量和挥发分,氮含量的影响与燃烧所采用的控制技术有关,随挥发分含量增加,NOx的生成量减少。     

燃用高硫无烟煤水泥熟料生产线分级燃烧应用实例

分析了水泥窑NOX的形成机理,介绍了分煤、分料、分风等分级燃烧技术的特点。西南某生产线分级燃烧测试结果表明,燃用高硫无烟煤的水泥熟料生产线NOx初始排放浓度高,分级燃烧降低了水泥熟料生产线SNCR脱硝前的NOx浓度,减轻了SNCR的脱硝压力,分级燃烧效率均值在16.38%,分级燃烧后、SNCR前的NOX平均值为1378.66mg/m^3(标)。