Pilot-Scale Evaluation of H2O2 Injection to Control NOx Emissions

Nitric oxide (NO) in combustion flue gasses can be converted to higher oxidation states by the injection of aqueous solutions of hydrogen peroxide (H2O2) into the hot flue gases. The NO is oxidized to NO2, HNO2, and HNO3, which can then be removed in a wet scrubber. A pilot plant system that was designed, constructed, and operated at Kennedy Space Center confirmed previous results that H2O2 is very effective at oxidizing NO; conversions of NO above 90% were obtained at temperatures of about 500°C (930°F) using mole ratios of H2O2:NOx slightly above 1.0. The mole ratios of H2O2∕NOx needed to obtain high conversions of NO were significantly lower in the pilot plant that they had been in previous laboratory studies, demonstrating that this process can be an economically feasible method for NOx control. The position of the injector and the type of atomization were very important to the efficient utilization of peroxide. When SO2 was present in the flue gas, both NO and SO2 were oxidized without increasing the demand for peroxide.     

Effect of Sulfate Ions on YAG Powders Synthesized by Microwave Homogeneous Precipitation

Using Al(NO3)3·9H2O, NH4Al(SO4)2·12H2O, Y(NO3)3 as mother salts, and urea as precipitant, YAG nano-powders were synthesized by microwave homogeneous precipitation. The composition, morphology, and phase transformation of precursor were analyzed by IR, XRD and TEM. The size distribution of YAG powders was characterized using laser diffraction method. The results show that sulfate ions influence the dispersion, composition and morphology of the YAG precursors. The addition of moderate sulfate ions can produce YAG powders with nano size and excellent dispersion at 1100 ℃.     

掺钕氧化钪激光透明陶瓷纳米粉体的合成及研究

研究了化学共沉淀法合成Nd:Sc2O3纳米粉的工艺.以Sc2O3为基质材料,掺杂0.5％(原子分数)的Nd3+,添加适量聚乙二醇(PEG)和(NH4)2SO,作为分散剂,以氨水(NH3·H2O)和碳酸氢铵(NH4HCO3)混合溶液作复合沉淀剂,采用化学共沉淀法获得了碱式稀土碳酸盐前躯体,在1100℃下煅烧该前躯体4h,制备出性能良好的Nd:Sc2O3纳米粉.采用热重-差热分析仪(TG/DSC)、红外光谱分析仪(IR)、X射线衍射仪(XRD)、透射电子显微镜(TEM)等测试手段对Nd:Sc2O3前躯体和煅烧后的粉体进行表征.实验结果表明:在室温下,用氨水和碳酸氧铵混合溶液作为复合沉淀剂合成出的前躯体为碱式稀土碳酸盐.通过XRD和EDS能谱分析,Nd3+完全固溶于Sc2O3的立方晶格中,这将有利于制备激光透明陶瓷.在1100℃的温度下煅烧此前躯体得到的Nd:Sc2O3纳米粉具有颗粒粒度小(约50 nm)、分散性好、团聚程度轻、结晶良好的性能.因此,采用此工艺合成的粉体将有可能制备出的Nd:Sc2O3透明陶瓷.     

亚铵法治理低浓度SO2生产工艺实践与理论分析

低浓度二氧化硫烟气一直是困绕钼冶炼烟气治理的技术难题。通过对治理低浓度二氧化硫生产工艺实践与理论分析，以碳酸氢铵作为吸收剂，采用了亚铵法生产工艺流程并进行一系列改造，可实现生产过程连续稳定运行，尾气二氧化硫排放浓度能达到国家环保排放要求。     

氧化球团烟气中SO2和H2O(g)对SCR脱硝的影响

选择性催化还原(SCR)具有效率高、技术成熟的优势,但处理球团烟气需要加热才能达到SCR脱硝的反应温度,导致能耗和运行成本高.氧化球团预热Ⅱ段(PH段)烟气温度在300℃以上,满足SCR反应所需温度,但是烟气中含有的SO2和H2O(g),会对催化剂的脱硝性能产生影响.研究了 PH段烟气中SO2和H2O(g)对V/Ti催...     

Investigation of Ultraviolet Light-Enhanced H2O2 Oxidation of NOx Emissions

Injecting aqueous solutions of hydrogen peroxide (H2O2) into hot flue gases can convert nitric oxide (NO) to higher oxidation states (NO2, HNO2, and HNO3), which can then be removed in a wet scrubber. The optimum temperature for such conversion is 500°C (930°F), at which H2O2 is thermally “activated” (split into free radicals). At lower temperatures ultraviolet (UV) light can be used to activate the peroxide molecules. In this pilot plant study at Kennedy Space Center, experiments were done with none, one, or two UV lamps on, with and without SO2 present in the flue gases, at various temperatures, and with various injection rates of peroxide. Temperatures ranged from 117 to 350°C (243 to 660°F), and the molar ratios (peroxide to NOx) ranged from 0.68 to 5.02. Conversions of NO varied from below 10 to above 70%, with the highest conversions occurring with higher temperatures, higher dosages of hydrogen peroxide, and with both UV lamps turned on. Conversions of NOx ?(NO+NO2) varied from below 5 to above 40%. The presence of SO2 did not inhibit NO or NOx conversion.     

Sulfur poisoning and regeneration of MnOx-CeO2-Al2O3 catalyst for soot oxidation

MnOx-CeO2-Al2O3 mixed oxides were prepared by impregnating manganese and cerium precursors on alumina powders via a sol- gel deposition method. The oxide catalyst exhibited a poor resistance to sulfur dioxide after the treatment in 100 ppm SO2/air at 350 °C for 50 h. The formation of manganese sulfate and especially cerium sulfate reduced the availability of surface active metal oxides, blocked the pore structure and decreased the surface area of the catalyst. These changes in chemical and structural and textural properties resulted in a severe loss in the activities of the sulfated catalyst for NO and soot oxidation. The decomposition of sulfates was almost complete during the calcina-tion in air at 800 °C for 30 min, which partially recovered the surface active sites and the catalyst surface area despite the significant sintering of metal oxides. Consequently, the NOx-assisted soot oxidation activity of the catalyst was regenerated to some extent by the oxidation treatment.     

Synthesis Yttrium Aluminum Garnet Precursor via Homogeneous Precipitation under Microwave Irradiation

The lowly-agglomerated single-phase YAG nanopowders were synthesized for the first time by the microwave homogeneous precipitation in the presence of urea. The composition and transformations during calcination of YAG precursor were analyzed by IR, DTA/TG and XRD. The size and morphology of YAG powders were characterized by LD and TEM methods. Results show that amorphous precursor synthesized under [urea]/[metal ions]molar ratio of 15 crystallizes directly to single-phase YAG at 900℃ . The size distribution and sinterability of YAG powders are obviously improved by adding( NH4 )2SO4 into the reaction solution. YAG powders obtained from precursor with the( NH4 )2SO4 content of 8% have good sinterability and are highly densified at a temperature of 1500℃.     

N236-HSCN体系萃取分离锆铪的盐效应研究

以乙酸戊酯作为稀释剂,采用N263-HSCN体系对锆、铪进行萃取分离,分别研究了(NH4)2SO4、NH4Cl、NH4NO3、NaCl和MgCl2等盐析剂的种类和浓度对锆与铪萃取分离的影响。结果表明,N263-HSCN体系分离锆、铪时优先萃取铪,该体系中SCN-的稳定性要比MIBK-HSCN体系强。不同阳离子的盐析剂对锆和铪的萃取率影响顺序为：NaCl>MgCl2>NH4Cl,对分离系数影响不大。不同阴离子的盐析剂对锆的萃取率顺序为：NH4NO3>NH4Cl>(NH4)2SO4,铪的萃取率顺序为：(NH4)2SO4>NH4Cl>NH4NO3,而分离系数顺序为：(NH4)2SO4>NH4Cl>NH4NO3,与阴离子的水合能力强弱顺序一致。当(NH4)2SO4加入量为0.6 mol/L时,分离系数达18.56,此时对锆和铪的萃取率分别为41.72%和93%。     

Simultaneous Desulfurization and Denitrification by Microwave Catalytic over FeCoCu/Zeolite 5A Catalyst

FeCoCu/zeolite 5A was used as a catalyst for microwave catalytic desulfurization and denitrification and for microwave catalytic reduction of SO2 and NOx with ammonium bicarbonate (NH4HCO3) as a reducing agent. Microwave catalytic desulfurization and denitrification efficiency attained 99.5 and 86.1%, respectively. The reaction efficiencies of microwave catalytic reduction of SO2 and NOx could be up to 95.8 and 95.1% separately; the optimal microwave power and empty bed residence time on microwave catalytic reduction of SO2 and NOx simultaneously are 280 W and 0.358 s, respectively. Microwave accentuates catalytic reduction treatment, and microwave addition can increase the SO2 and NOx removal efficiency. The microwave catalytic SO2 and NOx removal follows the Langmuir-Hinshelwood model.     

Respiration rates for determining the effects of urea on the soil-surface organic horizon of a black spruce stand

The respiration rates of microflora of layers of soil-surface organic horizon of a black spruce (Picea mariana (Mill.) B.S.P.) stand have been studied manometrically under controlled conditions of moisture, temperature, and aeration in the presence of urea and other nitrogen and mineral amendments. L.F., and F2 samples from field plots fertilized with 448 kg N/ha as urea in 1961 had still in 1971 greater respiration rates than similar samples from unfertilized field plots. In lab tests, addition of urea (112, 280, and 448 kg N/ha or 875, 2187, and 3500 ppm N) stimulated the endogenous respiration of each layer. The stimulation was greater when 2187 ppm N was applied and when moisture and temperature of the layers were maintained at 60% water-holding capacity and 20 degrees C during the 42-day incubation period. Addition of Mg, Ca, and K to urea-fertilized layers increased respiration while P and S decreased it. Addition of NH4NO3 and (NH4)2SO4 impaired the endogenous respiration. The endogenous respiration and moisture, temperature, and fertilizer effects decreased in the order L,F1, and F2 layers.     

Sintering and Reactivity of CaCO3-Based Sorbents for In Situ CO2 Capture in Fluidized Beds under Realistic Calcination Conditions

Sintering during calcination/carbonation may introduce substantial economic penalties for a CO2 looping cycle using limestone/dolomite-derived sorbents. Here, cyclic carbonation and calcination reactions were investigated for CO2 capture under fluidized bed combustion (FBC) conditions. The cyclic carbonation characteristics of CaCO3-derived sorbents were compared at various calcination temperatures (700–925°C) and different gas stream compositions: pure N2 and a realistic calciner environment where high concentrations of CO2>80–90% (and the presence of SO2) are expected. The conditions during carbonation employed here were 700°C and 15% CO2 in N2 and 0.18% or 0.50% SO2 in selected tests, i.e., typically expected for a carbonator. Up to 20 calcination/carbonation cycles were conducted using a thermogravimetric analyzer (TGA) apparatus. Three Canadian limestones were tested: Kelly Rock, Havelock, and Cadomin, using a prescreened particle size range of 400–650?μm. In addition, calcined Kelly Rock and Cadomin samples were hydrated by steam and examined. Sorbent reactivity was reduced whenever SO2 was introduced to either the calcining or carbonation streams. The multicyclic capture capacity of CaO for CO2 was substantially reduced at high concentrations of CO2 during the sorbent regeneration process and carbonation conversion of the Kelly Rock sample obtained after 20?cycles was only 10.5%. Hydrated sorbents performed better for CO2 capture, but also showed significant deterioration following calcination in high CO2 gas streams. This indicates that high CO2 and SO2 levels in the gas stream lead to lower CaO conversion because of enhanced sintering and irreversible formation of CaSO4. Such effects can be reduced by separating sulfation and carbonation and by introducing steam to avoid extremely high CO2 atmospheres, albeit at a higher cost and/or increased engineering complexity.     

微波消解技术应用于难分解贵金属化合物的分析

提出了微波密闭快速消解难分解的KAu(CN)2,KAu(CN)4,Pt(NH3)2(NO2)2,K2[Pt(NO2)4],Pt(NH3)2Cl2,Pt(NH3)4Cl2,(NH4)2PtCl6,K2PtCl4,Pt(C5H7O2)2等化合物的方法。比较了微波密闭消解法与传统分解法的条件;采用精密电化学滴定法分析了Au和Pt的含量,并与传统分析方法BS5658法(H2SO4发烟重量法)、火试金法和湿法重量法进行了结果对照。结果表明:以HCl-H2O2,HCl-HNO3分别为Au和Pt类化合物的消解试剂,于优     

撞击流-活性炭吸附法制备氧化钇超细粉体

以Y( NO3)3·6H2O和碳酸氢铵为原料,在撞击流反应器中制备碳酸钇,经焙烧得到超细氧化钇粉体.考察了分散剂加入量、反应物摩尔比n( NH4HCO3)/n(Y(NO3)3)、活性碳用量、反应温度、反应时间、搅拌速度以及碳酸钇的焙烧温度和焙烧时间等因素对Y2O3粒径的影响,并用WJL激光粒度仪、TG、XRD和SEM等表征手段对产品进行表征,从而获得制备超细氧化钇的优化工艺条件为:PEG4000的质量为硝酸钇的3％,活性炭用量为0.025 mol·L-1,反应物摩尔比n( NH4HCO3):n(Y( NO3)3)为8:1,反应温度50℃,反应40 min,螺旋桨转速1000 r·min-1,800℃下焙烧1.5h,在此条件下制得球形氧化钇超细粉体,表观粒径小于0.5μm.     

Catalytic Decomposition of CFC-12 over Solid Super Acid Mo2O3/ZrO2

Catalytic decomposition of dichlorodifluoromethane (CFC-12) in the presence of water vapor and oxygen was studied over a series of solid super acids Mo2O3/ZrO2 that had different ZrO2 content by using a fixed-bed reactor. CO2 and CClF3 were the main products and no CO was detected as by-product. The decomposition activity of solid super acid largely depended on the content of ZrO2 and the calcination temperatures of Mo2O3/ZrO2. The optimal calcination temperature and content of ZrO2 for preparing Mo2O3/ZrO2 with the highest activity for catalytic decomposition of CFC-12 were 450°C and 20–40 wt?%, respectively. Adopting a low concentration of oxygen and CFC-12 together with a high concentration of water vapor was preferable for having the high conversion efficiency of CFC-12 and the selectivity for CO2. The catalytic activity of Mo2O3/ZrO2 remained steady for 100 h in continuous operation.     

Simultaneous Removal of Nitrogen and Phosphorous from Municipal Wastewater Using Continuous-Flow Integrated Biological Reactor

A pilot-scale experiment was carried out to study the simultaneous removal of nitrogen and phosphorous from municipal wastewater by an innovative continuous-flow integrated biological reactor (CIBR) process. A three-phase separator was used in the CIBR process, which not only saved energy consumption of sludge returning, but also solved the sludge–gas separating problem. The optimal working condition was 2?h aeration, 1?h agitation, and 1?h settling, with an energy consumption of 0.23?kW?h/m3. The average removal of chemical oxygen demand (COD), ammonia nitrogen (NH4+–N), total nitrogen (TN), and total phosphorus (TP) under the optimal conditions were 72.87, 75.23, 61.25, and 68.25%, respectively. The distributing rules of dissolved oxygen, pH, mixed liquid suspended solid, COD, NH4+–N, NO3?–N, TN, and TP in each phase of CIBR was studied. It was indicated that the appropriate condition was created for the simultaneous removal of nitrogen and phosphorus in the integrated reactor. The study demonstrated the feasibility of using CIBR process for simultaneous removal of nitrogen and phosphorus at the average temperature 12.2°C.     

碱式碳酸铋制备工艺的改进研究

传统的碱式碳酸铋制备方法二氧化碳产出量大、泡沫多，工艺复杂繁琐。文章介绍了由硝酸铋与氨水和碳酸氢铵分步反应制备碱式碳酸铋的改进生产工艺，该工艺较原生产方法操作简单、易控制、省时、生产效率高、节约能源、产品纯度高。     

Y2O3对NiCr-Cr3C2金属陶瓷涂层热腐蚀性能影响行为研究

本文利用超音速火焰喷涂技术(HVOF),在20G钢表面制备了掺杂1wt.%、3wt.%、5wt.%三种不同含量Y2O3的NiCr-Cr3C2金属陶瓷复合涂层,并探究了其在650℃,Na2SO4/K2SO4熔盐环境中的热腐蚀性能。利用扫描电镜(SEM)、显微硬度计、拉伸试验机等对涂层的微观结构和力学性能进行了表征,利用X射线衍射仪(XRD)、拉曼光谱、X射线能谱仪(EDS)对复合涂层热腐蚀产物形貌、物相进行分析。结果表明掺杂1wt.%Y2O3的NiCr-Cr3C2复合涂层结构致密、孔隙率低、结合强度高,显微硬度达到801HV。热腐蚀过程中掺杂Y2O3的NiCr-Cr3C2复合涂层表面均生成耐蚀性良好且致密的Cr2O3膜。随着Y2O3掺杂量的增加,涂层的耐热腐蚀性能先升高后下降,当Y2O3掺杂量为1wt.%时,复合涂层表现出最佳的耐热腐蚀性能。     

H_2SO_4-NH_4F-SbF_3粗锑电解精炼体系研究

采用循环伏安法和线性扫描技术等电化学研究方法,系统研究了电解液体系中各阴阳离子对锑电沉积过程的影响。通过测定Sb3+、NH+4、F-、SO2-4及草酸等组分不同质量浓度下体系的循环伏安曲线、稳态极化曲线及塔菲尔曲线,分析了各离子在电解过程中的电化学行为及作用,确定了H2SO4-NH4F-SbF3电解液体系合适的成分为Sb3+90~120 g/L、NH+450 g/L、F-80 g/L、H2SO4360 g/L、H2C2O44~10 g/L。在此电解液体系下进行了粗锑的电解精炼试验,阴极锑纯度为99.943 6%,达到国标1号精锑标准,阴极电流效率为97.60%。     

热处理对1Cr12Ni3Mo2VN马氏体耐热钢组织和性能的影响

试验1Cr12Ni3Mo2VN钢（/%:0.13C,0.16Si,0.70Mn,11.42Cr,2.78Ni,1.67Mo,0.30V,0.0360N）的冶金流程为30t EAF-LF-VD-3t ESR-锻造成Φ350mm材。研究了950~1100℃淬火和200~700℃回火对1Cr12Ni3Mo2VN钢组织与性能的影响以及500℃,500~10000h时效的拉伸性能。结果表明,淬火温度950~1100℃对1Cr12Ni3Mo2VN钢力学性能的影响不明显;该钢的回火脆性区在600℃左右,但对钢的塑性的影响较小。经1040℃淬火、540℃回火的1Cr12Ni3Mo2VN钢,在500℃时效500h后,其抗拉强度和屈服强度分别下降了7.7%和5.8%,时效10000h后,其抗拉强度和屈服强度分别下降了13.4%和14.6%,断面收缩率下降了40%,主要原因是杂质元素在晶界处偏聚以及碳化物在晶界处析出。