SNCR/烟气再循环协同脱硝技术研究

短期内煤炭作为我国主要能源的现状不会改变。由于煤燃烧会释放大量NO_x,造成严重的环境污染,因此煤炭燃烧过程中的NO_x控制至关重要。链条锅炉作为我国工业应用最为广泛的燃煤锅炉之一,是降低NO_x排放的重点对象,尤其在新实施的GB 13271—2014《锅炉大气污染物排放标准》中规定重点地区锅炉NO_x排放值不得高于200 mg/m~3后,链条炉低氮燃烧和NO_x脱除技术受到广泛关注。为降低链条锅炉NO_x排放,满足国家环保要求的同时,降低企业运行维护成本,提高企业经济效益,以西安高新区某供热站4×75 t/h链条锅炉为研究对象,进行烟气再循环与SNCR耦合低氮燃烧NO_x脱除技术改造研究。研究了SNCR与烟气再循环耦合低氮燃烧系统参数,如烟气再循环率,再循环烟气一、二次风室送入比例,氨氮摩尔比,锅炉负荷变化等脱硝系统参数对NO_x脱除效率及链条炉燃烧特性的影响,确定了烟气再循环与SNCR技术耦合脱硝的最佳运行参数,结果表明:SNCR耦合烟气再循环低氮燃烧技术能有效降低链条锅炉NO_x排放。烟气再循环率为16%～18%,再循环烟气一次风室送入比例为82%,氨氮摩尔比为0.78时,SNCR耦合烟气在循环脱硝系统可达最佳脱硝效率。此时SNCR耦合烟气再循环联合脱硝效率可达到56%,SNCR单独运行脱硝效率可达40%,NO_x实际排放可从250 mg/m~3降至110 mg/m~3,远高于国家NO_x排放标准。     

锅炉烟气脱硝改造总结

总结现有锅炉烟气脱硝的三种技术方法:SCR脱硝——选择性催化还原法;SNCR脱销——选择性非催化还原法;SNCR/SCR脱销——选择性催化还原法工艺与选择性非催化还原法工艺混合法。结合锅炉实际情况,采用选择性非催化还原技术(SNCR)对锅炉烟气脱硝进行改造,锅炉外排烟气氮氧化物稳定达标排放。     

SNCR脱硝技术在45t循环流化床锅炉中的应用

介绍了开封龙宇45 t/h循环流化床燃煤锅炉烟气排放现状,对SNCR脱硝技术进行了对比并选择了氨法SNCR脱硝技术进行应用。改造后烟气中氮氧化物(以下简称NO_x)排放浓度降低了70%以上,达到了预期效果。     

循环流化床锅炉超低排放（低氮燃烧+SNCR）探索及实践

山东省某化工企业现有3台循环流化床锅炉,近几年来历经了两轮减排技改,锅炉排放烟气中的SO_2、烟尘指标已达超低排放要求,影响烟气达标排放的主要污染物是NO_X。为此,在对国内脱硝工艺和市场深入考察调研的基础上,综合考虑诸多因素,最终选取"低氮燃烧+SNCR"优化组合脱硝工艺于2019年9—10月先行对3#锅炉实施了超低排放改造。3#锅炉改造后的运行考核结果表明,烟气NO_X排放指标达到《火电厂大气污染物排放标准》(DB 37/664—2019)超低排放要求。鉴于"低氮燃烧+SNCR"优化组合工艺投资低、施工周期短、不增加占地、系统运行安全可靠、节能减排效益显著的技术优势,目前该企业正在对1#、 2#锅炉实施同样的改造。实践表明,"低氮燃烧+SNCR"优化组合脱硝工艺尤其适用于未预留脱硝装置场地的老锅炉改造,可作为中小型循环流化床锅炉脱硝超低排放技改的首选工艺路线。     

SNCR+SCR脱硝效果的影响因素分析

SNCR+SCR联合脱硝是当前中小型循环流化床锅炉烟气脱硝的主要工艺选择。本文从SNCR+SCR联合脱硝实际运行效果出发,分析了不同锅炉运行状态下NO_x的排放情况。主要结论如下:SNCR+SCR脱硝工艺能够满足当前NO_x脱硝超低排放要求,但仍要注意氨逃逸问题。烟气含氧量的适当增加有助于SNCR+SCR脱硝;炉膛温度上升导致NO_x初始生成量上升,在喷氨控制不佳的情况,NO_x排放浓度上升。氨的投加量并不是越多越好,需建立合理的氨投加控制方法,实现NO_x的稳定排放。     

水泥窑低氮燃烧+SNCR脱硝系统设计及运行经验

国家对水泥工业氮氧化物排放控制要求越来越严格,SNCR烟气脱硝技术正逐步在水泥行业推广.本论文结合新型干法水泥生产线SNCR脱硝系统工程设计实例,阐述了SNCR脱硝工艺设计选型原则和经验;分析了运行效果、使用成本;提出了系统实际运行中相关注意事项.     

浅谈锅炉烟气脱硝工程设计

为降低锅炉烟气中氮氧化物对环境的污染,以氨为还原剂采取烟气脱硝工艺技术将烟气中的NOx还原为N2,从而使烟气中NOx的排放达到国家标准要求,减少对大气、环境的污染。同时对烟气脱硝的工艺、催化剂和还原剂的选择等进行比较。     

催化还原反应在燃煤锅炉烟气脱硝中的应用

抚顺石化公司洗涤剂化工厂动力分厂燃煤锅炉烟气脱硝装置采用选择性催化还原法(SCR)烟气脱硝工艺,利用液氨与氮氧化物的氧化还原反应以达到氮氧化物排放达标的目的。通过对脱硝装置的建设,有效降低了氮氧化物的排放浓度,排放浓度达到环保排放要求。     

SNCR烟气脱硝还原剂选择的分析

对火力发电厂的中小流化床锅炉的烟气处理,采用SNCR烟气脱硝工艺可以实现脱硝高效率、NO_x低浓度排放的目的。通过对采用尿素和氨水两种不同还原剂的SNCR脱硝工艺进行分析比较,认为以氨水作还原剂的SNCR脱硝工艺可靠性和性价比最高,在实际生产中更符合市场需求。     

生物质锅炉烟气脱硝工艺技术研究

收集整理了生物质成型燃料锅炉大气污染物排放的国家标准和部分省市的地方标准,统计了6个生物质焚烧锅炉的燃料工业分析和灰分分析数据,对生物质锅炉的排放标准、燃料特性、烟气特性进行了研究,调研了可供生物质锅炉烟气脱硝选择的7种技术,并重点介绍了选择性催化还原技术(SCR)及其3种布置形式。通过对7种脱硝工艺及其优缺点进行细致的分析与研究,建议在NO_x排放浓度要求不严的区域,优先选用低氮燃烧技术、选择性非催化还原技术(SNCR)(或替代技术)者两者结合;在要求NO_x实现超低排放的区域,可选用低氮燃烧技术、SNCR技术(或替代技术)、SCR技术或多种联合脱硝技术。     

焦油一次汽化温度计算方法的探讨

利用相平衡原理得出的焦油蒸馏时一次汽化温度的计算方法,其结果与按经验公式的计算结果进行了比较,同时讨论了一次汽化温度与焦油馏分产率及二段蒸发器过热蒸汽用量的关系。     

Techniques for screening adhesives for structural applications

—Due to its chemistry, no structural adhesive system (epoxies, acrylics, etc.) is likely to offer an ideal combination of toughness, strength, moisture resistance, and ambient-temperature curing. Therefore, for effective use of adhesives in primary structures, an engineer must be able to identify adhesives that represent an optimum compromise among the different properties. In this paper, we present techniques for screening high-strength, ambient-temperature-curing adhesives for (1) moisture resistance under sustained loading and (2) fracture resistance in a way that is directly related to joint performance.     

Efficacy for Whitlockite for Augmenting Spinal Fusion

Whitlockite (WH) is the second most abundant inorganic component of human bone, accounting for approximately 25% of bone tissue. This study investigated the role of WH in bone remodeling and formation in a mouse spinal fusion model. Specifically, morphology and composition analysis, tests of porosity and surface area, thermogravimetric analysis, an ion-release test, and a cell viability test were conducted to analyze the properties of bone substitutes. The MagOss group received WH, Group A received 100% beta-tricalcium phosphate (β-TCP), Group B received 100% hydroxyapatite (HAp), Group C received 30% HAp/70% β-TCP, and Group D received 60% HAp/40% β-TCP (n = 10 each). All mice were sacrificed 6 weeks after implantation, and micro-CT, hematoxylin and eosin (HE) staining, and Masson trichome (MT) staining and immunohistochemistry were performed. The MagOss group showed more homogeneous and smaller grains, and nanopores (<500 nm) were found in only the MagOss group. On micro-CT, the MagOss group showed larger fusion mass and better graft incorporation into the decorticate mouse spine than other groups. In the in vivo experiment with HE staining, the MagOss group showed the highest new bone area (mean: decortication group, 9.50%; A, 15.08%; B, 15.70%; C, 14.76%; D, 14.70%; MagOss, 22.69%; p < 0.0001). In MT staining, the MagOss group demonstrated the highest new bone area (mean: decortication group, 15.62%; A, 21.41%; B, 22.86%; C, 23.07%; D, 22.47%; MagOss, 26.29%; p < 0.0001). In an immunohistochemical analysis for osteocalcin, osteopontin, and CD31, the MagOss group showed a higher positive area than other groups. WH showed comparable bone conductivity to HAp and β-TCP and increased new bone formation. WH is likely to be used as an improved bone substitute with better bone conductivity than HAp and β-TCP.     

Demand Increases for New Fungicides for Rice

<正> After June this year China's regions growingmiddle and late rice had widespread blastand sheath/culm blight.Such diseasesplagued 19.2 million hectares.Starting fromJuly the market for new fungicides that cancontrol blast and sheath/culm blight for ricewas more and more active.Makers of traditional pesticides for thecontrol of blast have to contend with fiercecompetition from new pesticides in marketthis year.Kitazine,iprobenfos,isoprothiolane and tricyclazole,oftenused by farmers in the past,are graduallybeing replaced by new varieties with high