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1.
Nitrogen doping of activated carbon （AC） was performed by annealing both in ammonia and nitric oxide, and the activities of the modified carbons for NO reduction were studied in the presence of oxygen. Results show that nitrogen atoms were incorporated into the carbons, mostly in the form of pyridinic nitrogen or pyridonic nitrogen. The effect of nitrogen doping on the activities of the carbons can be ignored when oxygen is absent, but the doped carbons show desirable activities in the low temperature regime （≤500 ℃） when oxygen is present. The role of the surface nitrogen species is suggested to promote the formation of NO2 in the presence of oxygen, and NO2 can facilitate decomposition of the surface oxygen species in the low temperature regime 相似文献
2.
Carcinogenic and mutagenic polycyclic aromatic hydrocarbons (PAHs) generated in coal combustion have caused great environmental health concern. Seventeen PAHs (16 high priority PAHs recommended by USEPA plus Benzo[e]pyrene) present in five raw bituminous coals and released during bituminous coal combustion were studied. The effects of combustion temperature, gas atmosphere, and chlorine content of raw coal on PAHs formation were investigated. Two additives (copper and cupric oxide) were added when the coal was burned. The results indicated that significant quantities of PAHs were produced from incomplete combustion of coal pyrolysis products at high temperature, and that temperature is an important causative factor of PAHs formation. PAHs concentrations decrease with the increase of chlorine content in oxygen or in nitrogen atmosphere. Copper and cupric oxide additives can promote PAHs formation (especially the multi-ring PAHs) during coal combustion. 相似文献
3.
To investigate the structural features and provide an alternative method for high value-added utilization of coal, Lingwu coal was first extracted with organic solvent at room temperature. Then its extraction residue was oxidized in aqueous sodium hypochlorite(ASHC) under mild conditions. The effects of oxidation conditions, such as temperature, reaction time, the ratio of Lingwu coal extraction residue(LCER, g) to ASHC(m L) and p H value, on the product distributions and compositions were investigated. The results of gas chromatography/mass spectrometry(GC/MS) suggested that 53 kinds of methyl esterified products were detected in total, and benzene carboxylic acids were the main oxidation products, while chloro-substituted benzene carboxylic acids were the main by-products. Higher yield and fewer kinds of organic acids could be obtained at lower p H value, especially for the main objective product, benzene carboxylic acids. 相似文献
4.
Quantum chemical simulation was used to investigate the catalytic mechanism of Na/K on NO-char heterogeneous reactions during the coal reburning process. Both NO-char and NO-Na/K reactions were considered as three-step processes in this calculation. Based on geometry optimizations made using the UB3LYP/6-31G（d） method, the activation energies of NO-char and NO-Na/K reactions were calculated using the QCISD（T）/6-311G（d, p） method; Results showed that the activation energy of the NO-Na/K reaction （107.9/82.0 kJ/mol） was much lower than that of the NO-char reaction （245.1 kJ/mol）. The reactions of NaO/KO and Na2O/K2O reduced by char were also studied, and their thermodynamics were calculated using the UB3LYP/6-31G（d） method; Results showed that both Na and K can be refreshed easily and rapidly by char at high temperature during the coal reburning process. Based on the calculations and analyses, the catalytic mechanism of Na/K on NO-char heterogeneous reactions during the coal reburning process was clarified. 相似文献
5.
《浙江大学学报(A卷英文版)》2021,(3)
Ce and Mn modified TiO_2 sorbents(CeMnTi) were prepared by a co-precipitation method,and their ability to remove elemental mercury from coal gas in a fixed bed reactor was studied.Based on results of Brunauer-Emmett-Teller(BET),X-ray diffraction(XRD),scanning electron microscope(SEM),and X-ray photoelectron spectroscopy(XPS) studies,the modification mechanisms of the CeMnTi sorbents are discussed.Mn doping improved the specific surface area and dispersion of cerium oxides on the sorbent surface,while Ce doping increased the proportion of Mn4+in manganese oxides by a synergetic effect between manganese oxides and cerium oxides.The effects of the active component,temperature,and coal gas components on the mercury removal performance of the sorbents were investigated.The results showed that the CeMnTi sorbents exhibited high mercury removal efficiency.Ce_(0.2)Mn_(0.1)Ti adsorbed 91.55% elemental mercury from coal gas at 160℃.H_2 S and O_2 significantly improved the ability of sorbents to remove mercury.Part of the H_2S formed stable sulfates or sulfites through a series of oxidation reaction chains on the sorbent surface.HCl also improved the mercury removal performance,but reduced the promotion effect of H_2S for mercury removal when coexisting with H_2S.CO and H_2 had a minor inhibitory effect on mercury adsorption.The recycling performance of the sorbents was investigated by thermal regeneration.The thermal decomposition of the used sorbents indicated that mercury compounds were present mainly in the form of HgO and HgS,and higher temperature was beneficial for regeneration.The formation of sulfates and sulfites in the presence of H_2S led to a decrease in mercury removal efficiency. 相似文献
6.
Sewage source heat pump unit operates under partial load most of the time, and study on the law of coefficient of performance (COP) of the unit varying with load ratio can provide basis for the heat pump units running in high efficiency. A mathematical model determining COP, evaporation temperature and condensation temperature of a single unit was proposed. Under the condition of uniform load distribution, the model was established according to different ways of bearing partial load with the same type multiple units but different parallel operation models, and the operation characteristics of units were analyzed as well. Results show that the single screw water-source heat pump can maintain high COP only at 60%—100% load ratio, COP decreases sharply with the decrease of load ratio, and the units with parallel operation are controlled by the load ratio of a single unit according to the reduction of total load which can keep the average COP at high level within a wide load range. 相似文献
7.
Auto-ignition and heat release correlations for controlled auto-ignition(CAI)combustion were derived from extensive in-cylinder pressure data of a four-stroke gasoline engine operating in CAI combustion mode.Abundant experiments were carried out under a wide range of air/fuel ratio,speed and residual gas fraction to ensure that the combustion correlations can be used in the entire CAI engine operation range.Furthermore,a more accurate method to compute the residual gas fraction was proposed by calculating the working fluid temperature at the exhaust valve close timing in the experiments.The heat release correlation was described in two parts,one is for the first slower heat release process at low temperature,and the other is for the second faster heat release process at high temperature.Finally the heat release correlation was evaluated on the single cylinder gasoline engine running with CAI combustion by comparing the experimental data with the 1-D engine simulation results obtained with the aid of the GT-Power simulation program.The results show that the predicted loads and ignition timings match closely with the measurements. 相似文献
8.
WAN Xian-kai ZOU Xue-quan SHI Hui-xiang WANG Da-hui 《浙江大学学报(A卷英文版)》2007,8(5):707-711
Nitrogen doping of activated carbon loading Fe2O3 was performed by annealing in ammonia, and the activity of the modified carbon for NO reduction was studied in the presence of oxygen. Results show that Fe2O3 enhances the amount of surface oxygen complexes and facilitates nitrogen incorporation in the carbon, especially in the form of pyridinic nitrogen. The modified carbon shows excellent activity for NO reduction in the low temperature regime (<500 °C) because of the cooperative effect of Fe2O3 and the surface nitrogen species. 相似文献
9.
Xiao-yuan Jiang Feng Du Chun-xia Guo Qiong Yang Xiao-ming Zheng 《浙江大学学报(A卷英文版)》2009,10(11):1651-1659
ZiO2 was prepared by the hydrolyzation method in （NH4）2SO4-modified TiCl4 solution, and TiO2 photocatalysts were obtained by accelerating the precipitation of TiO2 powder in a high-temperature water bath. The photocatalysts were characterized by Brunauer-Emmett-Teller （BET）, X-ray diffraction （XRD）, Raman spectrum and UV-Vis （Ultraviolet-Visible） spectrometry techniques, and the photocatalytic activity in phenol-contaminated water was investigated. The results showed that photocatalysts calcined at 400 ℃ had a specific surface area of 138.2 m^2/g and an average particle size of 9 nm, and a significant increase in thermal stability of anatase phase. At the calcination temperature of 700 ~C, the crystal form of TiO2 started to change into rutile （anatase： 97%, rutile： 3%）. The activity of TiO2 photocatalysts prepared with （NH4）2SO4-modified TIC14 solution was markedly stronger than that without （NH4）2SOg-modified TIC14 solution. Maximal photocatalytic activity was observed at the mole ratio of Ti：（NH4）2SO4= 1：2, the water-bath temperature of 90℃ and the calcination temperature of 700 ℃. 相似文献
10.
The first phase of the experimental investigation in our institute on pressur-ized fluidized bed combustion(PFBC)technology is introduced,and the results of fivetests are presented.The combustion efficiencies were as high as 97% 98% when high ashcontent coal was burnt in PFBC,and the sulphur retention efficiencics were 80%-85%with the Ca/S mole ratios between 1.5-1.8.The particulate content in flue gas at the out-let of high temperature gas clean-up system was 189mg/m~3(normalized).The average di-ameter of particles was 2.5-3μm and the weight fraction of particles with diameter largerthan 10μm was not greater than 3%. 相似文献
11.
气体再燃和SNCR技术是脱硝技术中较为常见的2种技术,并已初步投入使用。但已有的研究和应用表明,其再燃效率较低、运行费用较高、反应温度要求较严格,限制了这2种技术的进一步推广应用。结合气体再燃和SNCR 2种技术,对其反应机理及主要的影响因素进行了分析,得出了优化方案。结果显示:优化后的方案克服了传统再燃的脱硝效率较低的缺陷,同时也克服了氨水反应存在的缺陷,且该技术在经济上具有一定的优势。 相似文献
12.
刘立华 《唐山师范学院学报》2010,32(2):27-29
氢氧化镁阻燃剂属于无机阻燃剂,具有热稳定性好、无毒、低烟、不产生腐蚀性气体、价格低廉等优点,备受世界各国的青睐。本实验采用氨水法制备氢氧化镁无机阻燃剂,并通过实验讨论了初始反应温度和氨镁摩尔浓度比对反应转化率的影响。实验结果表明：最佳初始温度为20℃,氨镁摩尔浓度比为4：1。 相似文献
13.
Intheapplicationsofindustrialandcommercialrefrig erationsystem ,iftherequiredrefrigerationtemperatureisverylow ,theconventionalvaporcompressionsystemisdiffi culttomeettherequirementbecausewhenthedifferencebe tweentheevaporatingtemperatureandthecondensingtemper atureissohighthatitishardtofindarefrigeranttomeettheneedsasthecondensingpressureisnottoohighandtheevap oratingpressureisnottoolow .Whentherefrigeratingtemper atureisverylow ,thecascaderefrigerationcycleissuitabletobeused .Itcannotonlysat… 相似文献
14.
研究了以烟煤为原料制备颗粒活性炭的工艺过程 ,讨论了原煤炭、活化温度、活化时间、活性炭收率等工艺条件对活性炭吸附性能的影响。实验结果表明 ,煤制活性炭的最佳工艺条件 :粒度 180目 ,筛余量小于3% ,粘结剂用量为原料粉的 30 % ,炭化温度 5 6 0℃ - 6 0 0℃ ,合适活化温度 85 0℃ - 90 0℃。文章还讨论了煤制活性炭去除水污染物的效能及机理 相似文献
15.
Mechanicalvapourcompressioncyclesaremainlyemployedinmostrefrigerationsystems .Chlorofluoro carbons(CFCs)orhydrochlorofluorocarbons(HCFCs)aregenerallyusedasrefrigerantsinthesesystemsdrivenbyelectricityfromburningfossilfuels ,whichresultsino zonedepletionduetotheleakageandpoorrecoveryofthoseman maderefrigerants,andglobalwarmingowingtoCO2 emissionfrom powerstationsandthereasonisthatCFCsorHCFCsarepowerfulgreenhousegases.Inaddition,otherenvironmentalissuesarealsocausedbytheNOx,SO2 andpartic… 相似文献
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随着CFC和HCFC类物质淘汰进度的加快,液氨毒性和安全性的限制,CO2作为制冷剂的使用也越来越被人们看好。CO2／NH3复叠式制冷技术的提出和应用在国内虽然做了不少的研究和试验,但是大多集中在系统循环的分析和系统的优化。本文从CO2／NH3复叠式在冷冻冷藏工程中的应用方面对有关技术问题进行了分析。 相似文献
18.
Thirty-six daily time interval PM2.5 samples were collected in different seasonal dates in urban Shanghai, and the concentrations of four anions （Cl- , NO3-, SO4^2-, C2O4^2-） and five cations （NH＋, Na＋, K＋, Ca2＋, Mg2＋） were analyzed with ion chromatography. Sulfate, nitrate and ammonium were found to be the dominant species, accounting for about 80% of the total ions. The daily nitrate to sulfate mass ratio ranged from 0.31 to 0.82, indicating that coal combustion was still the main pollution source in Shanghai. The equivalent ratio of ammonium to stun of nitrate and sulfate showed fixed diurnal variation pattern in all the sampling days with higher values in the nighttime, suggesting that fine particles in the night were more neutralized. The oxalate to sulfate ratio was lower in the winter sampling days than that in hotter summer and autumn sampling days. Oxalate was significantly correlated with sulfate in winter sampling days, but not in the summer and autumn, suggesting that the formation mechanism of oxalate and sulfate was similar in winter, however different in hot days. 相似文献