用活性填料催化氧化-硝酸吸收法脱除氮氧化物的研究

为了提高硝酸吸收氮氧化物的效率,对活性填料催化氧化-硝酸吸收NOx进行了研究.结果表明:活性填料能明显提高NOx的吸收效率;当NOx中NO2体积百分含量增加,其吸收效率增加;随进气浓度和液气比的增大,NOx吸收效率增加;随NO2浓度的增加,NO的吸收效率先增加后减少,在NO/NO2为3时,NO吸收效率最高;随NO的增加NO2的吸收效率先增加后减少,在NO/NO2为0.6～1之间,NO2的吸收效果较好.     

流化床掺烧生活垃圾及尾气净化实验研究

在一燃煤流化床上进行了掺烧垃圾的实验，研究了不同掺烧比对燃烧效率、SO2、HCl、N0、N20、二恶英和重金属排放的影响。实验结果表明，随垃圾加入量的增加，飞灰含碳量降低，燃烧效率增加；HCl排放浓度增加，N0和SO2排放量减少，N2O先降低后增加；灰渣中二恶英含量随垃圾加入量的增加而增加；底渣和旋后飞灰中，Cr、Cu、Zn的含量均随垃圾加入量的增加而增加。采用三相流态化净化装置对尾气排放进行了净化处理，当吸收剂为石灰石浆液，浆液浓度为1％，循环倍率为3，喷射速度为5m／s—15m／s，鼓泡管插入深度为140mm时，流态化吸收式垃圾焚烧烟气净化装置的脱硫效率大于90％，脱硝效率在20％—30％之间，脱氯效率大于80％，除尘效率达99％，重金属净化效率大于99％，二恶英净化效率为99％。     

填料塔中的DBU溶液吸收CO_2

在自制的1,8-二氮杂双环[5,4,0]十一碳-7-烯(DBU)吸收CO2的填料塔中,研究DBU溶液浓度、入口CO2浓度、DBU溶液流量、气体流量、气体温度以及填料层高度对CO2吸收的影响。结果表明,DBU溶液浓度从1.5%增加到25%,CO2吸收容量和吸收效率均逐步减小;入口CO2浓度从4.5%增加到15%,CO2吸收容量和吸收效率均逐渐增大;DBU溶液流量从20 m L/min增加到120 m L/min,CO2吸收容量和吸收效率略有增加;气体流量从0.7 L/min增加到3.3 L/min,填料层高度从5 cm增加到45 cm,CO2吸收容量和吸收效率均呈先增后减趋势;气体温度从25℃增加到60℃,CO2吸收容量和吸收效率略有下降。DBU溶液在填料塔内能够高效吸收气体中的CO2。     

还原剂对Ag／Al2O3催化剂上NO还原的影响

在富氧条件下，研究了CH4、C3H8、C3H6、C8H18CH3OH、C2H5OH，以及C3H6与CH30H、C3H6与C2H50H组合作还原剂时，在Ag／Al2O3催化剂上NO的还原活性。结果表明，不同碳氢化合物还原NO的活性温度存在较大的差异。SO2的存在会导致CH，OH还原NO的活性提高，而其他碳氢化合物还原NO的活性降低。随着还原剂浓度提高，NOx转化率增大，不过，过高的还原剂浓度对NO还原不利。组合使用CH，OH与C3H。或C2H，OH与C3H。作为还原剂，能显著拓宽活性温度范围。     

尿素/三乙醇胺吸收烟气NO_x的实验研究

以尿素作为吸收液,与NOx反应生成N2和CO2,脱除烟气中的氮氧化物。以一套双级串连的填料塔为主体反应器,分别对气速、液气比、反应物浓度、添加剂浓度和反应温度等参数对尿素溶液吸收NOx反应的影响进行了实验研究,获得了优化实验工况,研究结果显示,在气速为0.1 m/s、液气比为16 L/m3、三乙醇胺为0.01%（质量比）、尿素浓度为13%（质量比）工况下,反应温度为30~70℃,脱硝总效率可达50%以上,且随着NOx体积分数增加而提高。     

氨-Fe(Ⅱ)EDTA法同步脱硫脱硝中试研究

在中试吸收塔反应器中,以氨基湿法烟气脱硫为基础,结合Fe(Ⅱ)EDTA络合吸收NO技术,实现同步脱硫脱硝;采用单一变量法研究了塔型、填料几何特性、填料层高度、液气比和Fe(Ⅱ)EDTA浓度等因素对同步脱硫脱硝的影响。结果表明,在相同的条件下,填料塔比空喷塔和鼓泡塔有利于同步脱硫脱硝;空隙率高、填料因子小的填料能明显提高脱硫脱硝效率,填料层高度从0 mm增加到900 mm,脱硫脱硝效率分别增大了4.49%和19.55%;液气比和Fe(Ⅱ)EDTA浓度越大,脱硝效率越高,但对SO_2的吸收没有影响。最佳工艺条件为:ф25 mm鲍尔环作填料且填料层高度为900 mm的填料塔、液气比为12 L/m~3、Fe(Ⅱ)EDTA浓度为0.05 mol/L,在此条件下,脱硫脱硝效率分别达到100%和51.55%。     

鼓泡反应器中Na_2S对低浓度NO_x的吸收

实验研究了在鼓泡反应器中硫化钠溶液吸收低浓度NO_x的吸收特性,分析了NO_x、O_2、Na_2S和Na OH浓度对吸收过程的影响,以及被吸收NO2的形态。结果显示,Na2S浓度在15.8和47.5 mmol·L~(-1)时,气相中NO2浓度变化对吸收率影响不明显,但在0.30~3.25 mmol·L~(-1)时,NO2浓度变化对吸收率有较大影响。气相中的O2会加速吸收反应,但同时也引起吸收剂的额外消耗。当Na2S溶液中加入Na OH,浓度达到0.1%时,可强化NO_2的吸收。NO_x中NO含量增加会导致吸收率下降,即使有Na OH的条件下,也未观察到NOx氧化度为0.5时NO与NO2的协同吸收效应。Na2S溶液将被吸收的NO2一部分还原为N2,一部分还原为NO-2。     

DOC系统催化性能的仿真和分析

以Langmuire Hinshelwood机理为理论依据,基于MATLAB/Simulink建立DOC系统的数值计算模型,研究不同参数(如空速、氧气浓度、NO2/NOx比例)对氮氧化物(NOx)、一氧化碳(CO)、碳氢化合物(HC)转化效率的影响,并对部分工况进行了实验研究,从而验证数值模型的准确性。结果表明,空速的降低可以增大DOC对CO、HC、NO的氧化性能,这是由于排气在催化器内的反应时间增长。当排气温度为225~300℃时,减小空速对增大HC的氧化效率效果明显,当排气温度在175~450℃范围内,减小空速对增大NO的氧化效率影响明显;当O2浓度低于1%,排气温度在175~250℃时,CO转化效率增大,在250℃之后均接近100%。当O2浓度为10%时,温度的变化对CO的转化效率影响很小。当O2浓度大于1%时,温度的变化对NO的氧化效率影响较大;当排气温度在300~550℃时,NO2/NOx比例的变化对NO的转化效率影响较大。降低排气中NO2/NOx比例,能够在排气温度高于300℃时,明显提高NO的转化效率。     

CeO2-CoO／ACF低温SCR烟气脱氮性能的研究

活性炭纤维（ACF）经硝酸处理后采用浸渍法制备了CeO2-CoO／ACF复合催化剂,测试了其在以氨气为还原剂的低温SCR过程中的催化活性,同时研究了金属氧化物浸渍顺序及负载量、催化剂煅烧温度、空速比（SV）、NH,／NO（摩尔比）、O2含量等因素对NO转化效率的影响。研究发现,负载量为10％的CeO2-CoO／ACF复合催化剂经煅烧后在120—240℃时具有很高的催化活性,并且在N0初始浓度为1000mg／m3、空速比（SV）为6000h～、NH3／NO为1．05、O：体积分数在3．0％时具有较高的NO转化效率。     

填料塔中Na_2CO_3吸收高浓度H_2S的传质特性

在填料吸收塔中考察了Na2CO3溶液吸收高浓度H2S气体的气液传质特性。通过测量填料塔进出口气体中H2S浓度计算了Na2CO3溶液吸收高浓度H2S气体的总体积传质系数(KGa),并研究了进气流速、吸收液流量、吸收温度和吸收液浓度对KGa的影响。结果表明,KGa随Na2CO3浓度、吸收液流量的增加而增加,随吸收温度、进气流速的升高而降低;在高浓度H2S吸收过程中液相传质阻力不能忽略。     

水吸收法处理低浓度氮氧化物废气的中试研究

对水在中试规模下吸收低浓度的氮氧化物废气进行了研究。分别研究了喷淋密度、温度、压力、气速以及氮氧化物浓度对吸收效果的影响,结果表明,综合考虑各种因素,喷淋密度在20 m3/（m2·h）,水温在15℃以下,气速小于0.28 m/s,废气浓度在400 mg/m3左右时,氮氧化物的平均脱除率可以达到50%左右;同时,随着压力的增大,吸收效率也增加。     

工业废气中氮氧化物的治理研究

对碱液吸收和活性炭吸附两级联合治理氮氧化物废气进行了实验研究,结果表明:对于氮氧化物进口浓度为7000～10 000 mg/m3的氮氧化物废气,氮氧化物的平均脱除率可以达到99%,出口浓度低于99 mg/m3;还进行了以硝酸溶液、双氧水溶液和高锰酸钾溶液为氧化剂湿法氧化碱吸收的实验研究,结果显示3种氧化剂都能显著提高氮氧化物的脱除率,其中以高锰酸钾溶液作氧化剂的脱除效果最好,其次是双氧水溶液.     

Photocatalytic oxidation of NOx using composite sheets containing TiO2 and a metal compound

The photocatalytic oxidation of nitrogen oxides (NO(x)) over titanium dioxide (TiO(2)) sheets containing metal compounds (MCs) had been studied. Calcium oxide (CaO), magnesium oxide (MgO), calcium carbonate (CaCO(3)), aluminium oxide (Al(2)O(3)) and ferric oxide (Fe(2)O(3)) were used as MCs. Al(2)O(3) and Fe(2)O(3) added to the TiO(2) sheet did not affect the photooxidation of nitrogen oxides (NO(x)). The CaO sheet treated with TiO(2) sol had the greatest efficiency as a NO(x) remover under UV irradiation. It is believed that CaO has a high adsorptivity for nitrogen dioxide (NO(2)) and nitric acid (HNO(3)). The amount of NO(x) removed by a TiO(2) sheet including MC showed a tendency to increase with increasing pH of the MC suspension, i.e. there is a good correlation between the alkalinity of the MC and the retention of NO(2) and HNO(3).     

Cleaning of Stack Gases Containing High Concentrations of Nitrogen Oxides

Multistage gas absorption of 1–50% nitric oxide, nitrogen dioxide, and nitrogen tetraoxide from air with water or caustic solutions can produce colorless stack discharges. The rate at which NO is oxidized to No₂ in the gas phase and the solubility rate of No₂ in water or solution are highly concentration dependent so that reductions of stack gas concentrations of nitrogen oxides below approximately 200 ppm appear to be impractical. High efficiency absorption combined with elevated discharge of the cleaned, colorless gases is an acceptable method of air pollution control for many troublesome operations. Experiences in the fields of rocketry and nuclear energy are cited. Engineering modifications of metal pickling operations have been found especially helpful in producing effective control at an acceptable cost.     

Photocatalytic oxidation of nitrogen oxides using TiO2 loading on woven glass fabric

TiO2 loading on woven glass fabric is applied to treat nitrogen oxides (NOx) by photocatalytic oxidation (PCO). In this paper, the PCO behavior of NO at high concentrations was studied by PCO of NOx at source levels (20-168 ppm). The PCO efficiency reached 27% in this experiment, while the inlet NOx concentration was 168 ppm (147 ppm NO). The dependency of the reaction rate on several key influencing factors (relative humidity, space time, inlet concentration, oxygen percentage) was also studied. The results illustrate that the resulting hydroxyl radical and active oxide play an important role in the oxidation of NOx. The reactions are limited by the thermodynamic equilibrium after ca. 15s space time. A possible explanation for the catalyst deactivation is the accumulation of nitric acid and nitrous acid on the TiO2 surface during the PCO of NOx. However, the photocatalytic activity can be recovered with a simple heat treatment. The results from the study of the effect of the inlet concentration were described with the Langmuir-Hinshelwood model.     

Comparative study on the removal efficiency of hydrogen sulfide (H2S) using three different packings

To improve the removal efficiency on hydrogen sulfide (H₂S), a biofilter was developed and was made of polyvinyl chloride (PVC) pipes. The effects of three different packings (i.e., packing A, packing B, and packing C), containing different proportions of activated carbon, sawdust, wormcast, perlite, and pig manure compost, based on different biofilter parameters on H₂S removal efficiency, were investigated. With the extension of running time, the H₂S removal rate of packing A reached up to 90.12%, that of packing B reached a peak at 92.96%, and that of packing C was highest at 87.21%. The contribution rate of each packing at the bottom of the device was significantly greater (p < 0.01) than that of other parts, and those of the top of the devices were all greater than those of the middle of the devices. The H₂S removal rate increased with greater filler layer height. The removal rate of group B increased first with humidity, and then declined, with the optimal humidity level for the removal of H₂S 50–65% in this study. With the prolongation of the run, the pH of packing A was reduced from 7.1 to 5.91, while the pH of packing B and C remained within the range of 6.53–7.10. An increase was found in the number of bacteria and fungi over time. The count of bacteria in packing B and C and following a decreasing order was bottom > middle > top, whereas that for fungi was the opposite. In conclusion, it is thought that packing B (comprising wormcast + sawdust + activated carbon) is more efficient in the removal of H₂S than the other packings and may thus be utilized in biofilters. These results hope to provide useful information for future related research on the removal efficiency of H₂S using packings.

Implications: Wormcasts use as biological filter packing to remove H₂S is limited and needs yet to be explored. A comparative study on the removal efficiency of H₂S using three packings showed the packings that included wormcast were more efficient than others, and showed the combined features of physical absorption and biological removal with long sustainability and good efficiency, although these were largely influenced by environmental factors and nutrient content for the microorganisms. In summary, wormcast could be utilized in biological filters in the future in related research beacuse of its good efficiency and low cost.     

3种短链脂肪酸对活性污泥储存PHA的影响

采用经乙酸钠驯化培养具有一定聚羟基烷酸酯(PHA)储存能力的活性污泥,考察乙酸、丙酸和丁酸3种短链脂肪酸,以及乙酸、丁酸分别与丙酸按1∶1、1∶2、2∶1比例组合成的6种混合酸作为碳源时对活性污泥中PHA的储存和转化的影响。实验结果表明,在3种短链脂肪酸中,以丁酸为碳源得到活性污泥PHA储存量最高,为40.53 mg/g;在混合酸中,乙酸与丙酸按1∶2组合时,系统PHA储存量最高,为773.4 mg/g。混合酸相对于单一的脂肪酸碳源更有利于活性污泥储存PHA。在混合酸总量一定的条件下,随着丙酸比例的增加,乙酸与丙酸混合比丁酸与丙酸混合更有利于微生物的PHA储存。     

气水比对曝气生物活性炭处理原水的影响

针对从臭氧-活性炭工艺中开发出来的预臭氧-曝气生物活性炭,在不同气水比工况下进行实验,分析了不同气水比对曝气生物活性炭处理微污染原水的影响与作用。结果表明:在滤速为8～12 m/h,空床接触时间为11.5～15.4 min,装填密度为510 g/L条件下,不同气水比对去除氨氮的影响大于对CODMn的影响。气水比为0.3∶1时,对氨氮浓度为1.65～2.10 mg/L范围的进水平均去除率为81.9%,亚硝酸盐氮平均积累率为1.4%,CODMn去除率为70.6%。当气水比逐渐增加时,氨氮平均去除率有所提高,亚硝酸盐氮积累率则有所下降,对较低浓度的CODMn影响不大。     

Consistency of ozone and nitrogen oxides standards at tropospherically relevant mixing ratios

The absolute accuracy and long-term precision of atmospheric measurements hinge on the quality of the instrumentation and calibration standards. To assess the consistency of the ozone (O3) and nitrogen oxides (NO(x)) standards maintained at the National Institute of Standards and Technology (NIST), these standards were compared through the gas-phase titration of O3 with nitric oxide (NO). NO and O3 were monitored using chemiluminescence and UV absorption, respectively. Nitrogen dioxide (NO2) was monitored directly by laser-induced fluorescence and indirectly by catalytic conversion to NO, followed by chemiluminescence. The observed equivalent loss of both NO and O3 and the formation of NO2 in these experiments was within 1% on average over the range of 40-200 nmol mol(-1) of NO in excess O3, indicating that these instruments, when calibrated with the NIST O3 and NO standards and the NO2 permeation calibration system, are consistent to within 1% at tropospherically relevant mixing ratios of O3. Experiments conducted at higher initial NO mixing ratios or in excess NO are not in as good agreement. The largest discrepancies are associated with the chemiluminescence measurements. These results indicate the presence of systematic biases under these specific conditions. Prospects for improving these experiments are discussed.