500MW机组脱硝系统喷氨格栅优化设计

合理的喷氨系统可保证烟气中的氮氧化物和脱硝剂氨均匀混合,有利于提高脱硝效率,节约氨耗量;减少催化剂预装量,延长催化剂寿命;保证达标排放,降低硫铵堵塞引发的安全风险;降低投资和运行管理成本。以某500 MW机组SCR系统为研究对象,设计3种不同形式的喷氨格栅进行数值模拟。选择催化剂入口截面速度和氨浓度分布最为均匀的方案,对原喷氨系统进行改造。结果表明:工程改造后,SCR出口NO_x浓度不均匀度由最高57.40%降低到20.20%,氨逃逸由最高24×10~(-6)降低到1×10~(-6),液氨耗量节约10%以上。     

超低排放脱硝喷氨格栅优化策略

超低排放改造后脱硝系统普遍出现氨逃逸大、空预器堵塞严重、喷氨自动无法投入等问题。通过仿真设计优化、喷氨格栅调整、精准喷氨改造等优化手段,能改善催化剂入口氨氮摩尔比,从而保证NOx减排系统的稳定运行。喷氨格栅优化能实现对氨逃逸的控制,可以减少还原剂耗量和降低引风机电耗,具有明显的经济性。     

啤酒厂发酵罐冷系统的节能

本文介绍发酵罐用氨冷却工艺来代替酒精水冷却工艺，可节能耗２０％以上，具有很好的经济效益。     

CDC和TDF型水泥分解炉烟气脱硝喷点布置的对比研究

水泥工业分解炉选择性非催化还原脱硝工艺系统的脱硝率受喷氨点布置有较大影响,本文针对2个具体工程项目,对比研究了CDC和TDF型水泥分解炉烟气脱硝喷点布置。研究表明,合理设置喷氨点,将使得喷入的氨能够与氮氧化物充分接触反应,从而不仅提高系统脱硝率,同时能降低氨耗量和氨逃逸率。     

加速技术进步 实现节能降耗

劲力公司是以煤为主要原料的小尿素企业 ,是一个耗能大户 ,节约能源对企业有着十分重要的意义。近年来 ,公司认真贯彻落实《节能法》和《重点用能单位节能管理办法》 ,不断加速节能技术改造的步伐 ,努力提高能源的利用率 ,取得了较好的实绩。2 0 0 2年共生产合成氨 6 2 914t ,吨氨两煤标耗 975kg ,吨氨工艺电耗 12 0 8kWh ,吨氨耗水 5 8m3,吨氨耗油0 8kg ,分别比定额下降 4 2 5kg ,2 93kWh ,4 2m3,2 4 0kg ;生产尿素 10 35 32t ,吨尿素耗标煤 14 7kg ,吨尿素耗电 134kWh ,分别比定额下降 5 3kg ,12 6kWh。全年共节约标煤 32 2 2 6t,节电…     

600 MW燃煤发电机组SCR分区动态喷氨改造

一600MW燃煤发电机组SCR烟气脱硝系统存在磨损严重、氨耗量大、氨逃逸高、空预器堵塞等问题,优化改造提升需求迫切。通过流场和分区动态喷氨改造,系统总体性能明显提升。催化剂入口截面气流速度分布相对标准偏差降低至8.71%,NH3质量分数分布相对标准偏差降低至1.92%,满足行业规范要求;平均喷氨量从160kg/h减小至105kg/h,最大喷氨量从280kg/h减小至130kg/h,喷氨波动明显降低,改造效果明显。     

闭式海洋温差能发电系统的工质研究

在不同冷凝温度条件下,以氨作为比较对象,选取R245ca、R245fa、R236ea、R236fa、正丁烷、异丁烷、正戊烷和异戊烷8种干有机工质,基于热力学第一定律和第二定律对其热力循环性能进行计算分析,并对工质的净功、热效率、气耗率和损失等进行比较。结果表明:在所选有机工质中,正戊烷具有最高的热效率和效率,最大的净功及最小的气耗率,且产生的系统损失较小;从净功方面比较,氨的做功能力远强于有机工质。     

基于数值模拟的SCR喷氨优化及反应潜能提升研究

在燃煤电厂机组超低排放改造后,SCR脱硝系统仍存在很多问题,如因空间有限导致的烟道布置不合理,造成脱硝流场、浓度场、氨氮比分布不均匀,氨耗量大,氨逃逸量高等。通过数值模拟计算对非对称布置的烟道进行优化设计,优化后催化剂入口流场相对标准偏差由35%下降为13%;通过冷态、热态喷氨优化调整,浓度场相对标准偏差由54%下降为14%;经效果评估,反应器反应潜能上升约0.8。     

基于NOx浓度场实时检测的喷氨优化应用研究

在国家新的大气污染排放标准要求下,需要对燃煤电厂脱硝系统反应器进行喷氨实时优化。在工程实践中,首先需解决NH_3/NO_x混合效率问题,其次解决脱硝系统出口的NO_x浓度场均匀性对催化剂寿命产生影响所带给电厂运行的经济性、安全性等问题。为此,对NO_x浓度场进行实时检测并深入研究了脱硝系统喷氨实时优化方案,提出一种模糊控制与均衡控制相结合的前馈串级控制方法。目前,该系统已成功应用在1 000 MW机组中,应用显示控制法可以有效减小耗氨量,提高出口NO_x的均匀程度,从而降低了机组运行电耗,增强了系统运行稳定性和可靠性,减少了氨逃逸,延长了催化剂使用寿命。给电力生产带来很好的经济效益,满足了脱硝工程中喷氨混合的需要。     

600 MW火电机组SCR脱硝系统“超低排放”改造性能试验

针对某电厂600 MW机组SCR(脱硝系统)进行超低排放改造,对其改造后的主要运行性能指标进行了现场试验,运行指标包括SCR系统的脱硝效率、氨逃逸、SO_2/SO_3转化率、系统阻力和氨耗量等。性能试验结果表明:SCR的主要性能指标均能达到设计的性能要求,改造后的SCR系统满足了近零排放的环保要求。本研究可为我国投运后的SCR现场性能考核、性能优化等提供可行且有效的技术方法。     

氨与燃料电池

氨作为一种富氢化合物，具有各种优点，特别是氧有着良好的产业基础，价格低廉，氨作为燃料电池燃料具有很大的发展潜力。按供氨方式的不同，氨燃料电池可分为直接供氨式燃料电池及间接供氨式燃料电池。直接供氨式燃料电池又有直接供氨式碱性燃料电池与直接供氨式固态氧化物燃料电池之分。对于间接供氨式燃料电池，存在着不同的氨分解装置与燃料电池的组合。将在阐明氨的特性的基础上，介绍了氨燃料电池的种类及基本工作原理，分析氨作为氢能源载体的优势及存在问题。     

Performance enhancement of ammonia-fueled engine by using dissociation catalyst for hydrogen generation

The effect of combustion of hydrogen generated by an ammonia dissociation catalyst on engine performance and exhaust emissions in a spark-ignition engine using ammonia-gasoline was investigated. An ammonia dissociation catalyst coated with 2% ruthenium on 3.175-mm alumina pellets were used in order to analyze the effect of the catalyst as an ammonia cracker to decompose ammonia into hydrogen and nitrogen. Results show that combustion of hydrogen generated by an ammonia dissociation catalyst resulted in improved engine performance and reduced exhaust emissions. The conversion rate of ammonia into hydrogen was affected by the flow rate of ammonia, and the catalyst was very effective at low to medium flow rates, resulting in significantly increased engine power and decreased fuel consumption. With the use of the catalyst, emissions of CO, HC, NH₃ and NOx were reduced considerably. Overall, it was demonstrated the ammonia dissociation catalyst can enable ammonia to be used as a hydrogen carrier for use in internal combustion engines effectively.     

Highly purified hydrogen production from ammonia for PEM fuel cell

Liquid ammonia is an attractive hydrogen carrier because of high storage capacity. According to ISO14687-2, an acceptable ammonia concentration in hydrogen for polymer electrolyte membrane (PEM) fuel cell vehicles is 0.1 ppm. When ammonia is used as the hydrogen carrier, about 1000 ppm of ammonia included in gas generated by ammonia decomposition at 773–823 K and 0.1 MPa has to be reduced to less than 0.1 ppm. Although several types of ammonia absorption materials are investigated as ammonia remover, the target value cannot be achieved by static adsorption methods. However, we have succeeded in that the ammonia concentration is reduced down to 0.01–0.02 ppm by using Li-exchange X-type zeolite (Li-X) as the absorbent and dynamic adsorption methods. Furthermore, Li-X is simply recycled by heating at 673 K. Therefore, Li-X is a durable and recyclable ammonia removal material for the highly purified hydrogen production from ammonia for PEM fuel cells.     

Recent advances in ammonia synthesis technologies: Toward future zero carbon emissions

As a carbon-free molecule, ammonia has gained great global interest in being considered a significant future candidate for the transition toward renewable energy. Numerous applications of ammonia as a fuel have been developed for energy generation, heavy transportation, and clean, distributed energy storage. There is a clear global target to achieve a sustainable economy and carbon neutrality. Therefore, most of the research's efforts are concentrated on generating cost-effective renewable energy on a large scale rather than fossil fuels. However, storage and transportation are still roadblocks for these technologies, for example, hydrogen technologies. Ammonia could be replaced as a viable fuel for a clean and sustainable future of global energy. More efforts from governments and scientists can lead to making ammonia a clean energy vector in most energy applications. In this review, ammonia synthesis was assessed, including conventional Haber–Bosch technology. Current hydrogen technologies as the key parameters for ammonia generation are also evaluated. The role of ammonia as a hydrogen-based fuel and generation roadmap are discussed for future utilization of energy mix. Further, ammonia generation processes are addressed in depth, including blue and green ammonia generation. A survey of ammonia synthesis catalytic materials was conducted and the role of catalyst materials in ammonia generation was compared, which showed that the Ru-based catalyst generated the maximum ammonia after 20 h of starting experiment. An end-use plan for using ammonia as a clean energy fuel in vehicles, marines, gas turbines as well as fuel cells, is briefly discussed to recognize the potential applications of ammonia use. The practical and future end-use vision of energy sources is proposed to achieve great benefits at low carbon emissions and costs. This review can provide prospective knowledge of large-scale aspects and environmental considerations of ammonia. Herein, we conclude that ammonia will become the “clean energy carrier link” that will achieve the global energy and economy sustainability targets.     

A comprehensive review on synthesis,chemical kinetics,and practical application of ammonia as future fuel for combustion

Recently, ammonia has been explored as a potential fuel for internal combustion engines, gas turbines and other industrial purposes. Ammonia consists of 17.6% by weight of hydrogen and is thus considered a carbon-free emission fuel. The synthesis of ammonia for bulk production takes place using the Haber-Bosch process. The production, storage and transportation of ammonia is relatively safe. This paper reports various aspects of ammonia as an alternative fuel for combustors. Several studies reporting the laminar burning velocity of ammonia and its blends are discussed. Recent advances in the development of chemical kinetics for ammonia combustion are presented. The paper explores all experimental and numerical works on ammonia as a fuel for I C engines, gas turbines and other combustion systems.This review further suggests ways to overcome the disadvantages associated with ammonia combustion, such as lower burning velocities and high NOx emissions.     

Environmental and economic evaluation of ammonia as a fuel for short-sea shipping: A case study

In this study, the environmental and economic effects of the ammonia-diesel dual-fuel engine are evaluated by a case study with the real voyage data of a ship. Thirteen scenarios are formed by three different fuel fractions and three different types of ammonia which are classified according to their production routes (brown, blue, and green ammonia). Brown ammonia has worse (137.7%) or slightly lower (3%) CO₂ emissions than MDO depending on the feedstock. Blue ammonia complies with the IMO 2030 target with a 42.8% CO₂ reduction while green ammonia from solar energy has a similar reduction capacity with blue ammonia, and green ammonia from wind energy provides 79.2% CO₂ reduction and complies with the 2050 target. SO_X and PM emissions are decreased up to 95% by ammonia usage. NO_X emissions are 19.4% lower at 60% ammonia energy fraction than MDO, but it increases 133.1% at 95% ammonia energy fraction. The selective catalytic reduction system is required for high ammonia energy fraction cases. The N₂O emission is an important issue during ammonia usage. The fuel expense analyses show that brown ammonia is cheaper and blue ammonia is slightly higher (8.8%–13.9%) than MDO. Green ammonia does not be feasible recently, due to its significantly high price.     

Exergy analysis of industrial ammonia synthesis

Exergy consumption of ammonia production plants depends strongly on the ammonia synthesis loop design. Due to the thermodynamically limited low degree of conversion of hydrogen–nitrogen mixture to ammonia, industrial ammonia synthesis is implemented as recycle process (so-called “ammonia synthesis loop”). Significant quantities of reactants are recycled back to reactor, after the removal of ammonia at low temperatures. Modern ammonia synthesis plants use well-developed heat- and cold recovery to improve the reaction heat utilisation and to reduce the refrigeration costs. In this work, the exergy method is applied to estimate the effect of the most important process parameters on the exergy efficiency of industrial ammonia synthesis. A specific approach, including suitable definitions of the system boundaries and process parameters, is proposed. Exergy efficiency indexes are discussed in order to make the results applicable to ammonia synthesis loops of various designs. The dependence of the exergy losses on properly selected independent process parameters is studied. Some results from detailed exergy analysis of the most commonly used ammonia synthesis loop design configurations at a wide range of selected parameters values are shown.     

Experimental investigation of stabilization and emission characteristics of ammonia/air premixed flames in a swirl combustor

Ammonia is a possible candidate for use as a hydrogen energy carrier as well as a carbon-free fuel. In this study, flame stability and emission characteristics of swirl stabilized ammonia/air premixed flames were experimentally investigated. Results showed that ammonia/air premixed flame could be stabilized for various equivalence ratios and inlet flow velocity conditions in a swirl burner without any additives to enhance the reaction of ammonia even though the laminar burning velocity of ammonia is very slow. The lean and rich blowoff limits were found to be close to the flammability limits of the ammonia flame. In addition, emission characteristics were investigated using an FTIR gas analyzer. The NO concentration decreased and ammonia concentration increased under rich conditions. Moreover, it was found that there is an equivalence ratio in rich condition in which NO and ammonia emission are in the same order.     

厌氧消化过程氨抑制研究进展

随着厌氧消化理论研究的不断深入,厌氧消化工艺的研发和应用取得了迅速的发展,但处理效率低和!运行稳定性差是厌氧消化中普遍存在的问题,其中氨积累引发氨抑制是主要原因之一。文章简述了厌氧消化过程中氨抑制产生的机理及氨抑制的主要影响因素,介绍了氨抑制过程中微生物变化规律研究现状,总结了消除和缓解氨抑制的方法,并提出了厌氧消化氨抑制的重点研究方向。     

Transient thermodynamic analysis of a novel integrated ammonia production,storage and hydrogen production system

A transient thermodynamic analysis is reported of a novel chemical hydrogen storage system using energy and exergy approaches. The hydrogen is stored chemically in ammonia using the proposed hydrogen storage system and recovered via the electrochemical decomposition of ammonia through an ammonia electrolyzer. The proposed hydrogen storage system is based on a novel subzero ammonia production reactor. A single stage refrigeration system maintains the ammonia production reactor at a temperature of −10 °C. The energy and exergy efficiencies of the proposed system are 85.6% and 85.3% respectively. The proposed system consumes 34.0 kJ of work through the process of storing 1 mol of hydrogen and recovering it using the ammonia electrolyzer. The system is simulated for filling 30,000 L of ammonia at a pressure of 5 bar, and the system was able to store 7500 kg of ammonia in a liquid state (1% vapor) in 1500 s. The system consumes nearly 45.3 GJ of energy to store the 7500 kg of ammonia and to decompose it to reproduce the stored hydrogen during the discharge phase.