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.     

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。     

生物膜法净化中浓度硫化氢的研究

基于中浓度H2S的生物治理研究较少的现状,利用生物膜法进行了以活性炭为填料净化中浓度H2S适宜条件的研究.考察了温度、营养液喷淋量、空塔气速、H2S初始浓度及pH与H2S净化效率的关系.结果表明,适宜条件为温度30 ℃、营养液喷淋量10 L/h、空塔气速0.16 m3/h、H2S初始质量浓度低于60 mg/m3和pH为2.0.在适宜条件下,生物膜填料塔对H2S的净化效率可达到90%以上.     

湿式烟气脱硫喷淋塔内部流场数值模拟研究

以300MW机组湿法烟气脱硫喷淋塔为研究对象,利用计算流体力学通用软件对其内部两相流场进行模拟。气相湍流由标准k 模型描述,喷淋液滴由拉格朗日颗粒轨道模型描述。预测了无喷淋和有喷淋2种条件下的气相湍流流场分布、沿塔高方向不同截面上的气速分布以及喷淋液滴的轨迹。模拟结果表明,引入喷淋液后,出口截面气速分布明显均匀化,其最大值由无喷淋时的12m/s降至6m/s。该最大值出现在靠近塔壁处,是由塔壁附近喷淋密度较低造成的,可通过改进周边喷嘴的布置方式及喷嘴型式进行优化。     

水溶性离子液体对甲苯的吸收效果及影响因素

选择3种水溶性离子液体(十二烷基咪唑氯盐(DDMIM Cl)、十二烷基咪唑硝酸盐(DDMIM NO_3)、十二烷基咪唑双氰胺盐(DDMIM DCA))作为研究对象寸模拟曱苯废气进行吸收实验,研究了吸收液的吸收性能、甲苯浓度、吸收液浓度、进气气速以及盐度等因素对吸收效果的影响以及加热蒸馏法对吸收液的再生与甲苯回收的可行性。结果表明:不同的离子液体对甲苯的吸收率不同J)DMIM DCA的吸收效果最好在质量分数为5%时,初始吸收率达到98%,饱和吸收量为53.39 mg·L~(-1),而DDMIM CKDDMIM NO_3对甲苯的初始吸收率在92%左右,饱和吸收量分别为33.60,37.01 mg·L~(-1);甲苯饱和吸收量与吸收液浓度、甲苯进气浓度呈正相关,与进气气速、含盐度呈负相关;传质系数与甲苯进气浓度、进气气速以及含盐度呈正相关,与吸收液浓度呈负相关;采用加热蒸馏法进行甲苯回收及吸收液再利用时用苯的回收效率达到85%~90%且甲苯的饱和吸收量随着重复利用次数的增加而基本保持不变。因此利用离子液体溶液处理甲苯废气理论上是可行的。     

基于正交实验的颗粒移动床烟气脱硫工艺参数优化

石灰石颗粒移动床脱硫工艺参数是影响脱硫效率和操作压降变化的重要因素,考虑到工艺参数对脱硫过程的影响,基于正交实验方法,通过直观分析和方差分析得到喷淋密度、空床气速、SO2浓度、烟气温度和床层下移速度对脱硫效率影响程度的主次顺序和脱硫效率与各因素之间的关系,并且分析了各因素对脱硫效率的影响规律。研究发现,各因素对脱硫效率的影响程度依次是空床气速>喷淋密度>SO2浓度>烟气温度>床层下移速度。喷淋密度对脱硫效率的影响高度显著,呈正相关;空床气速对脱硫效率的影响高度显著,呈负相关;SO2浓度和烟气温度对脱硫效率有影响但不显著,呈负相关。床层下移速度与脱硫效率呈正相关。     

基于亚铁螯合物络合吸收的NO和NO_2协同净化实验研究

基于乙二胺四乙酸亚铁螯合剂络合吸收的NO和NO_2协同净化工艺,一级净化采用铁屑填料床,利用螯合物吸收、铁屑还原净化NO,二级吸收采用鲍尔环清水喷淋塔,考察协同净化效果。结果表明:当NO进口质量浓度约为200mg/m~3、NO_2进口质量浓度约为70mg/m~3、螯合剂为0.02mol/L、液气比为3L/m~3、空塔气速为0.078m/s的条件下,一级出口NO降至75mg/m~3左右;在一级吸收塔螯合剂为0.02mol/L、液气比为3L/m~3和二级吸收塔氧化度(NO_2占NO_x的体积分数)为50%、液气比为4L/m~3的条件下,二级出口NO、NO_2分别可稳定在20、8mg/m~3左右。     

尿素/三乙醇胺吸收烟气NOx的实验研究

以尿素作为吸收液，与NO_x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NO_x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NO_x体积分数增加而提高。     

填料塔-微乳液增溶吸收法净化甲苯废气

利用甲苯可以和非离子表面活性剂及相应助表面活性剂水溶液形成微乳液,从而增大甲苯表观溶解度的特性,吸收净化甲苯废气。采用微乳液作为吸收剂的填料塔治理甲苯废气,探讨了吸收剂组成、表面活性剂种类及浓度、喷淋量、甲苯浓度负荷和助表面活性剂的加入及其种类对甲苯去除率的影响。结果表明,微乳液吸收处理甲苯废气具有显著的效果,最大去除率达41%;经过体系筛选采用Tween-20作为表面活性剂,此时最适喷淋量为40 L/h(液气比为1∶5),且随着甲苯浓度负荷的升高,甲苯去除率随之增加;添加助表面活性剂可以不同程度地提高甲苯的去除率,Tween-20/正丁胺/甲苯/水微乳体系为吸收甲苯的最佳体系,此时最高去除率可达65%。     

湿法烟气脱硫喷淋塔的持液特性

在喷淋塔内部增设湍流装置是提高脱硫效率的有效途径之一,因此以自行设计的湍流装置的冷态喷淋塔为对象,考察了气速、喷淋量、液气比(L/G)、湍流装置水平和垂直间距对其持液特性的影响。实验结果表明,当湍流装置结构形式一定时,液体在塔内的停留时间随气速的增大而增大,随喷淋量、L/G的增大而减小;湍流层的持液量随气速、喷淋量、L/G的增大而增大;当气速、L/G一定时,液体在塔内的停留时间和持液量均随湍流装置水平和垂直间距的增大而减小。当气速、喷淋量、L/G、湍流装置水平和垂直间距分别为3.6 m·s~(-1)、100m~3·h~(-1)、10 L·m~(-3)、X_1、Y_1时,液体的最大停留时间为24.58s;而当气速、喷淋量、L/G、湍流装置水平和垂直间距分别为m~3·h~(-1)、25 L·m~(-3)、X_1、Y_1时,湍流层的最大持液量为1.093 m~3。对实验数据进行多元线性回归分析,得出该湍流式喷淋塔持液量的经验公式,其拟合优度与显著性良好,对工业应用具有一定的参考价值。     

Regenerative thermal oxidation of airborne N, N-dimethylformamide and its associated nitrogen oxides formation characteristics

In this study, a two-bed electrically heated regenerative thermal oxidizer (RTO) was used to test the thermal destruction and oxides of nitrogen (NOx) formation characteristics in burning airstreams that contain either N, N-dimethylformamide or dimethylformamide (DMF) mixed with methyl ethyl ketone (MEK). The RTO contained two 0.152 m x 0.14 m x 1 m (L x W times] H) beds, both packed with gravel particles with an average diameter of approximately 0.0111 m and a height of up to 1 m with a void fraction of 0.42 in the packed section. The thermal recovery efficiency (TRE) and the gas pressure drop over the beds were also studied. Experimental results reveal that, with a valve shifting time (ts) of 1.5 min, a superficial gas velocity (Ug) of 0.39 m/sec (evaluated at an influent air temperature of around 30 degrees C) and preset maximum destruction temperatures (Ts) of 750-950 degrees C, no NOx was present in the effluent gas from the RTO when it was loaded with DMF-free air. When only DMF was present in the influent air, the average destruction efficiencies exceeded 96%, and increased with the influent DMF concentration from 300 to 750 mg/N x m3. The "NOx-N formation/DMF-N destruction" mass ratios were in the range 0.76-1.05, and decreased as the influent DMF concentration increased within the experimental range. When both DMF and MEK were present in the influent gas, the NO, formation ratio was almost the same and the DMF destruction efficiency increased with the influent MEK/DMF ratio from 150/300 to 4500/300 (mg/mg) and in the preset temperature range. The NOx formation ratios were in the range 0.75-0.96. The TRE decreased as Ug increased but was invariant with Ts. The Ergun equation was found to suffice in the estimation of the pressure drop when the gas flowed over the packing beds.     

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。     

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.     

湍球塔和喷淋塔的海水脱硫冷态实验对比

通过湍球塔和喷淋塔的海水脱硫冷态实验对比,研究海水脱硫过程中烟气和海水参数对湍球塔和喷淋塔脱硫的不同影响。实验结果表明,SO2分压力增大,脱硫效率和尾水pH值减小;海水碱度、pH值和液气比增大,脱硫效率和尾水pH值也随之增大;湍球塔的脱硫效率和尾水pH值与液气比改变方式无关,实验用湍球塔的合适液气比值为2.3 L/m3;湍球塔脱硫实验中,塔内气速为1.58 m/s,SO2分压力为20 Pa,水温为10.2℃,液气比为1.1~2.8 L/m3时,尾水pH值在2.4~2.8之间;增大液气比时,喷淋塔改变海水流量的脱硫效果要比改变气体流量的脱硫效果明显;塔内气速1 m/s以上时,一级喷淋塔的脱硫效率要比湍球塔小很多,有时只有湍球塔的1/2左右。     

散堆填料对海水脱硫吸收系统性能影响的实验研究

在海水烟气脱硫中试实验台上进行了填料形式、填料高度变化对脱硫效率和系统压降影响规律的实验研究;研究中将喷淋空塔和分别填装A型、B型、C型3种填料的吸收塔进行了综合性能对比,并进行了填料高度分别为0.6、1.2和1.8 m的对比实验。结果表明,填料塔的脱硫效率高于喷淋空塔;当空塔气速为3 m/s时,填装C型填料的吸收塔的综合性能最优;当空塔气速小于2.5 m/s时,填装A型填料的吸收塔的综合性能最优;在满足相同脱硫效率的指标下,虽然增加填料高度降低了海水喷淋量,并且系统压降出现一定比例下降,但是在工程设计中必须综合考虑塔高、填料支架载荷等因素选择合适的填料堆积高度。     

Effect of Diffusiophoresis and Thermophoresis on the Overall Particle Collection Efficiency of Spray Droplet Scrubbers

The overall particle collection efficiencies of spray scrubbers using monodisperse droplets of 100,500, and 1000 microns diameter were calculated for the cases of evaporating and condensing droplets. The properties of the gas at the inlet to the spray scrubber were maintained constant at 150°F, 100% relative humidity, and 1 atmosphere pressure. At the liquid entrance to the spray scrubber, the water droplet temperature was 50° F for the condensing case and 180° F for the evaporating case. The liquid to gas flow rate ratio for all the calculations was held constant at 4 gal/1000 acf. The gas velocity in the co-current spray tower was 1 ft/sec in the downwind direction. The calculation results show that for the particles in the 0.01 to 10 Mm diameter range, the overall spray scrubber particle collection efficiency is greater with the cooler 50°F water (condensing case) than with the warmer 180°F water (evaporating case). The effect of diffusiophoresis and thermophoresis is noticeable for all the water droplet sizes considered, but is more significant for the larger water droplets. This greater effect for the larger water droplets compared to the smaller droplets is due to the longer existence of the temperature and water vapor concentration gradients between the water droplets and the surrounding gas.     

Collection of Aerosol Particles by Electrostatic Droplet Spray Scrubbers

Theoretical calculations and experimental measurements show that the collection of small aerosol particles (0.05 to 5 micron diameter range) by water droplets in spray scrubbers can be substantially increased by electrostatically charging the droplets and particles to opposite polarity. Measurements with a 140 acfm two chamber spray scrubber (7 seconds gas residence time) showed an increase in the overall particle collection efficiency from 68.8% tit uncharged conditions to 93.6% at charged conditions, with a dioctyl phthalate aerosol (1.05 μm particle mass mean diameter and 2.59 geometric standard deviation). The collection efficiency for 0.3 μm particles increased from 35 to 87% when charged. During 1973–1974 a 1000 acfm pilot plant electrostatic scrubber was constructed inside a 40 ft trailer for evaluation on controlling particu-late emissions from pulp mill operations (funded by Northwest Pulp and Paper Association). Field tests performed on the particle emissions exhausting from SO₂ absorption towers treating the gases from a magnesium based sulfite recovery boiler have shown particle collection efficiencies ranging from about 60 to 99% by weight, depending on the electrostatic scrubber operating conditions. Energy requirements for the University of Washington electrostatic scrubber are about 0.5 hp/1000 acfm (350 Watts/1000 acfm) including gas pressure drop, water pressure drop, and electrostatic charging of the water spray droplets and the particles.     

Air quality impacts of power plant emissions in Beijing

The CALMET/CALPUFF modeling system was applied to estimate the air quality impacts of power plants in 2000 and 2008 in Beijing, and the intake fractions (IF) were calculated to see the public health risks posed. Results show that in 2000 the high emission contribution induced a relatively small contribution to average ambient concentration and a significant impact on the urban area (9.52 microg/m(3) of SO(2) and 5.29 microg/m(3) of NO(x)). The IF of SO(2), NO(x) and PM(10) are 7.4 x 10(-6), 7.4 x 10(-6) and 8.7 x 10(-5), respectively. Control measures such as fuel substitution, flue gas desulfurization, dust control improvement and flue gas denitration planned before 2008 will greatly mitigate the SO(2) and PM(10) pollution, especially alleviating the pressure on the urban area to reach the National Ambient Air Quality Standard (NAAQS). NO(x) pollution will be mitigated with 34% decrease in concentration but further controls are still needed.