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Efficient SNCR denitration technology

Source:Zhongtian Engineering DesignAuthor:Zhongtian Liu WeiyunLink:http://www.sdztte.com

First, the technical background

In recent years, with the rapid development of the domestic economy, nitrogen oxides (NOx) emissions of pollutants rapid increase in serious pollution of the environment, has become one of the important factors of socio-economic development. The main sources of nitrogen oxides are power generation, vehicle emissions and emissions from industrial boilers furnaces, which because of its thermal power plant emissions from large and relatively concentrated, easy to control than other diffuse sources, become the preferred target of state control NOx emissions. China has promulgated and implemented the five emission standards for thermal power plant air pollutants for coal-fired power plant NOx emission control standards more stringent.

Shandong Zhongtian Technology Engineering Co., Ltd. has been committed to the promotion of environmental technology research and development projects, the company introduced the German advanced SNCR flue gas denitrification technology, can efficiently remove nitrogen oxides in the flue gas.

Second, the technical profile

Selective non-catalytic oxidation-reduction method (Selective Non-Catalytic Reduction, SNCR) denitration technology is in the absence of a catalyst, a reducing agent in the flue gas NOX reduced to harmless nitrogen and water a denitration method. The process is NHx group-containing reducing agent (e.g., ammonia, urea), is injected into the furnace zone temperature of 800 ~ 1100 ℃, the reducing agent is rapidly decomposed into NH3 and NOx in the flue gas with the reduction reaction N2 and H2O . In this method, the reactor hearth furnace, the boiler can achieve transformation.

Ammonia, urea as a reducing agent in the main reaction:

4NH3 + 4NO + O2 = 4N2 + 6H2O

CO (NH2) 2 + 2NO + 1 / 2O2 = N2 + CO2 + 2H2O

Traditional SNCR modeling analysis has not been, for the furnace gun set is relatively simple, single, unable to meet the guarantee complete denitration efficiency while controlling ammonia slip.

Companies introducing advanced foreign technology denitration, fluid modeling analysis to select the optimum furnace denitration solutions. Companies serious and responsible treatment of each project, the engineering car, before commissioning, make adequate preparatory work. The first step of the furnace load performance, fuel (coal-fired), the load temperature and nitrogen oxide content was analyzed; the second step, the application of fluid dynamics software CFD (Computational Fluid Dynamics) to the boiler fluid mechanics, chemical modeling and build jet model; the third step, the simulation experiments, generating chemical kinetics based temperature profile, based on CKM judgment gun position, results of a preliminary judgment injection lance; the fourth step, the analysis of the expected injection performance, injection position illustrated, and in accordance with the requirements of the type of gun needed to complete the overall reaction simulation, analysis, and forecasting process. CFD software application to a large extent replaced the costly fluid dynamics laboratory equipment, the reaction proceeds, gun installation, injection has important guiding significance.

Third, the process flow diagram

Figure 1 is a combination of CFD software to simulate the flow chart of SNCR

Process is divided into three modules (1) reducing reagent preparation module; (2) a reducing agent delivery, metering module (3) reducing the allocation module. By reducing the preparation, metering, distribution after injection through the gun to the appropriate location of the furnace, and nitrogen oxides react. By measuring the amount of exhaust gas escaping ammonia and nitrogen oxides content is adjusted injection amount of reducing agent. SNCR flue gas denitration method by removing nitrogen oxides, nitrogen oxides can be reduced by 50% -70%

一、技术背景 近年来,随着国内经济的快速发展,氮氧化物(NOx)污染物的排放量迅速增加,严重污染了生态环境,已成为制约社会经济发展的重要因素之一。氮氧化物的主要来源是火力发电、机动车排放和工业锅炉炉窑排放,其中火电厂因其排放量大且相对集中、较其他分散源容易控制,成为国家控制NOx排放的首选目标。我国先后五次颁布实施有关火电厂大气污染物的排放标准,对燃煤电站NOx的排放控制标准要求越来越严格。 山东中天科技工程有限公司一直致力于环保科技工程的研发推广,公司引进了德国先进的烟气SNCR脱硝技术,能够高效的脱除烟气中的氮氧化物。 二、技术简介 选择性非催化氧化还原法(Selective Non-Catalytic Reduction, SNCR)脱硝技术是在没有催化剂存在的条件下,利用还原剂将烟气中的NOX还原为无害的氮气和水的一种脱硝方法。该工艺是把含NHx基的还原剂(如氨、尿素),喷入炉膛温度为800~1100℃的区域,该还原剂迅速分解成NH3并与烟气中的NOx进行还原反应生成N2和H2O。该方法以膛炉为反应器,可通过对锅炉进行改造实现。 以氨水、尿素为还原剂的主要反应: 4NH3 + 4NO + O2 = 4N2 + 6H2O CO(NH2)2 + 2NO + 1/2O2= N2 + CO2 + 2H2O 传统的SNCR未经过建模分析,对于炉内喷枪设置比较简单、单一,无法满足保证脱硝效率的同时完成氨逃逸的控制。 公司引进国外先进脱硝技术,对流体进行建模分析,从而选择最优的炉内脱硝解决方案。公司认真负责对待每一个项目,在工程开车、试车前,做充分的前期工作。第一步,对炉内负荷性能、燃油(燃煤)情况、负荷温度及氮氧化物含量进行分析;第二步,应用流体动力学软件CFD(Computational Fluid Dynamics)对锅炉内流体进行力学、化工动力学建模及建立喷射模型;第三步,进行模拟实验,生成化学动力学为基础的温度分布图,基于CKM判断喷枪的位置,初步判断喷枪的注入结果;第四步,分析喷射的预期性能,对喷射位置图解,并根据要求所需要的喷枪类型,完成整个反应的模拟、分析、预测过程。CFD软件的应用在很大程度上替代了耗资巨大的流体动力学实验设备,对反应的进行,喷枪的安装、喷射等具有重要的指导意义。 三、工艺流程图 图1为结合CFD软件模拟的SNCR流程图 工艺主要分为三个模块(1)还原试剂的配制模块;(2)还原剂的输送、计量模块(3)还原剂的分配模块。还原剂通过配制、计量、分配后通过喷枪注入到适合的炉膛位置,并与氮氧化物进行反应。通过测量尾气的氨逃逸量及氮氧化物含量调节还原剂的注入量。通过SNCR烟气脱硝法脱除氮氧化物,可使氮氧化物减少50%-70%。一、技术背景 近年来,随着国内经济的快速发展,氮氧化物(NOx)污染物的排放量迅速增加,严重污染了生态环境,已成为制约社会经济发展的重要因素之一。氮氧化物的主要来源是火力发电、机动车排放和工业锅炉炉窑排放,其中火电厂因其排放量大且相对集中、较其他分散源容易控制,成为国家控制NOx排放的首选目标。我国先后五次颁布实施有关火电厂大气污染物的排放标准,对燃煤电站NOx的排放控制标准要求越来越严格。 山东中天科技工程有限公司一直致力于环保科技工程的研发推广,公司引进了德国先进的烟气SNCR脱硝技术,能够高效的脱除烟气中的氮氧化物。 二、技术简介 选择性非催化氧化还原法(Selective Non-Catalytic Reduction, SNCR)脱硝技术是在没有催化剂存在的条件下,利用还原剂将烟气中的NOX还原为无害的氮气和水的一种脱硝方法。该工艺是把含NHx基的还原剂(如氨、尿素),喷入炉膛温度为800~1100℃的区域,该还原剂迅速分解成NH3并与烟气中的NOx进行还原反应生成N2和H2O。该方法以膛炉为反应器,可通过对锅炉进行改造实现。 以氨水、尿素为还原剂的主要反应: 4NH3 + 4NO + O2 = 4N2 + 6H2O CO(NH2)2 + 2NO + 1/2O2= N2 + CO2 + 2H2O 传统的SNCR未经过建模分析,对于炉内喷枪设置比较简单、单一,无法满足保证脱硝效率的同时完成氨逃逸的控制。 公司引进国外先进脱硝技术,对流体进行建模分析,从而选择最优的炉内脱硝解决方案。公司认真负责对待每一个项目,在工程开车、试车前,做充分的前期工作。第一步,对炉内负荷性能、燃油(燃煤)情况、负荷温度及氮氧化物含量进行分析;第二步,应用流体动力学软件CFD(Computational Fluid Dynamics)对锅炉内流体进行力学、化工动力学建模及建立喷射模型;第三步,进行模拟实验,生成化学动力学为基础的温度分布图,基于CKM判断喷枪的位置,初步判断喷枪的注入结果;第四步,分析喷射的预期性能,对喷射位置图解,并根据要求所需要的喷枪类型,完成整个反应的模拟、分析、预测过程。CFD软件的应用在很大程度上替代了耗资巨大的流体动力学实验设备,对反应的进行,喷枪的安装、喷射等具有重要的指导意义。 三、工艺流程图 图1为结合CFD软件模拟的SNCR流程图 工艺主要分为三个模块(1)还原试剂的配制模块;(2)还原剂的输送、计量模块(3)还原剂的分配模块。还原剂通过配制、计量、分配后通过喷枪注入到适合的炉膛位置,并与氮氧化物进行反应。通过测量尾气的氨逃逸量及氮氧化物含量调节还原剂的注入量。通过SNCR烟气脱硝法脱除氮氧化物,可使氮氧化物减少50%-70%。

V. Projects

Shandong Zhongtian Technology Engineering Co., Ltd. introduced from abroad advanced denitrification technology, and applied to the actual production process, and achieved good denitrification effect.

It is to "Shanxi flat land 800,000 tons / year alumina project thermoelectric device 2 × 220t / h circulating fluidized bed boiler flue gas purification system - denitrification means" project as an example of denitration denitration technology and achievements outlined.

The project construction scale thermoelectric device 2 × 220t / h high temperature and high pressure circulating fluidized bed boiler to provide electricity and steam for the alumina production process. Boiler flue gas denitration device using SNCR flue gas denitrification, denitrification public system equipment by considering two furnaces, two furnaces and reserve expansion expansion position.

SNCR process design techniques include the transformation of the basis of the former boiler test conditions, the use of three-dimensional computational fluid dynamics before the boiler combustion simulation to compare simulation results with test data base condition to correct combustion model parameters and simulation denitration comprehensive transformation influence of the furnace flow and combustion conditions to guide SNCR gun arrangement. Numerical simulation confirmed the effect of stock optimal SNCR temperature window (950-1050 ℃) position, and 4 to 6 SNCR gun layout scheme, set up three guns, a total of 16 sets. Performance test results show as table:

Single 220t / h boiler performance table

五、工程实例 山东中天科技工程有限公司从国外引进先进脱硝技术,并应用于实际生产过程,取得了良好脱硝效果。 现以《山西平陆80万吨/年氧化铝项目热电装置2×220t/h循环流化床锅炉烟气净化系统-脱硝装置》项目为例对脱硝技术及脱硝成果简述。 本项目热电装置工程建设规模为2×220t/h高温高压循环流化床锅炉,为氧化铝生产工艺提供电力和蒸汽。锅炉烟气脱硝装置采用SNCR烟气脱硝,脱硝公用系统设备按2台炉考虑,并预留扩建2台炉扩建位置。 SNCR技术的工艺设计包括对锅炉改造前进行基础工况测试,采用三维计算流体力学对该锅炉改造前进行燃烧模拟,比较模拟结果与基础工况测试数据以校正燃烧模型参数,以及模拟脱硝综合改造对炉内流场和燃烧状况的影响以指导SNCR喷枪的布置。数值模拟确认了脱销效果最优的SNCR温度窗口(950-1050℃)位置,及4~ 6支SNCR喷枪的布置方案,喷枪设置三层,共16套。性能测试结果显示如表:  单台220t/h锅炉性能表

Note: 1) mg / Nm3 with reference to a standard state (273.15K, 1.013 × 105Pa) at 6% oxygen conversion from dry flue gas.

The project is running well, to achieve the desired effect of denitrification.