共查询到18条相似文献,搜索用时 156 毫秒
1.
《化工学报》2017,(11)
针对燃煤锅炉受热面存在的高温腐蚀问题,采用料浆法在20G钢材表面制备复合陶瓷涂层,烧结后的复合陶瓷涂层表面较为致密,涂层与基材具有良好的结合状态。对喷涂及未喷涂陶瓷涂层钢片在SO_2腐蚀气氛环境下的抗高温腐蚀性能进行试验,并采用热分析动力学方法对试验数据进行处理,结果表明,在400~500℃温度范围内,两种试样的腐蚀过程均符合一维扩散反应动力学模式,计算求得喷涂涂层钢片腐蚀反应活化能低于未喷涂涂层钢片,涂层具有较好的抗高温腐蚀性能。对腐蚀试验后试样的形貌、成分和物相分析结果显示,涂层在SO_2气氛下腐蚀后,表面生成K_2SO_4晶粒,但由于涂层较为致密,阻止了S的扩散,内部基本没有检测到K2SO4的存在。 相似文献
2.
为了提高碳材料的抗烧蚀性能,以石墨块作为基体,SiC(d50=10μm)、B4C(d50=50μm)、TaC(d50=3μm)为主要原料,采用料浆法结合反应熔渗Si在石墨材料表面制备了Si-SiC和Si-SiC-TaB2涂层,研究了涂层的物相组成、显微结构和元素分布,考察了Si-SiC-TaB2复合涂层在室温至1 600℃的抗热震性能,并通过等离子火焰烧蚀试验(2 350℃分别烧蚀120和1 980 s)测试了涂层对石墨材料高温下的抗烧蚀防护性能。结果表明:Si-SiC-TaB2复合涂层结构致密,涂层中SiC和TaB2陶瓷颗粒与Si无明显界面;在1 600℃热震循环20次后,涂层试样的质量基本逐渐增加,具有良好的抗热震性能;Si-SiC-TaB2复合涂层试样烧蚀1 980 s后质量增加,表面覆盖了含有Ta2O5和SiO2的Ta... 相似文献
3.
为提高湿法脱硫后烟囱内壁防护涂层的防腐性能,以氟碳树脂(PEVE)和聚四氟乙烯(PTFE)粒子为原料,采用喷涂工艺及室温固化制备出具有抗粘附性能的防腐蚀氟碳复合涂层。利用硫酸腐蚀实验、抗粘附冷凝实验、耐温实验、耐磨性实验,分别评价涂层的耐酸性、抗粘性、耐温性、耐磨性,并通过扫描电子显微镜对腐蚀前后涂层的形貌变化进行分析。结果表明,当PTFE∶PEVE的质量比为1∶2时,制备的PTFE/PEVE复合涂层在竖直倾角小于5°且酸气温度小于60℃时,表面未出现酸性冷凝液附着,具有优异的抗粘附特性;且分别经室温20%H2SO4浸泡90 d和低温(50℃)10%H2SO4的浸泡7 d,涂层表现出较强的耐酸性能;涂层表面能承受200℃的高温而不发生脱落、鼓包、开裂等现象,具有良好的耐温性能。此外,受力氟碳复合涂层在砂纸上拖行200 cm后,表面疏水角度降为150.2°,依旧保持超疏水状态,具有良好的耐磨性。 相似文献
4.
准东煤燃烧过程中Na2SO4的形成会造成锅炉受热面沾污、尾部SCR催化剂失活等问题。烟气中Na2SO4形成及转化规律的研究对于预测和控制燃煤烟气中Na2SO4的形成有重要意义。发展了烟气中Na/Cl/S/O/H化学动力学模型,研究了烟气中Na2SO4的生成过程及转化机理,考察了含氧量、温度、SO2浓度、H2O浓度等因素对Na2SO4生成的影响。动力学计算结果表明,模型预测结果与实验数据吻合较好,验证了模型的准确性。烟气中的高氧气含量有利于Na2SO4的生成。高温加快化学反应的同时,抑制了Na2SO4的生成。SO2和H2O的影响效果受温度影响较大。反应路径分析表明,Na2SO4的生成路径有两个:一是依赖于SO2直接氧化(NaCl→NaSO3Cl→NaHSO4→Na2SO4),二是依赖于SO2间接氧化(NaCl→NaO2→NaSO4→NaHSO4→Na2SO4)。敏感性分析结果表明,Na2SO4的生成主要对系统中生成或消耗自由基的反应更为敏感。 相似文献
5.
采用等温溶解平衡法研究了四元体系Na+,K+//Br-,SO42--H2O在373 K条件下的相平衡关系,测定了平衡溶液的溶解度和密度,并根据实验数据绘制相应的相图、水图和密度图。研究发现:交互四元体系Na+,K+//Br-,SO42--H2O在373 K温度下,有复盐钾芒硝Na2SO4·3K2SO4生成,相图由3个共饱和点、7条单变量曲线和5个结晶区组成。其中,5个结晶区分别对应单盐:K2SO4,KBr,NaBr,Na2SO4和复盐Na2SO4·3K2SO4(Gla)。 相似文献
6.
研究了碱金属化合物(K2SO4)对活性炭(AC)担载五氧化二钒(V2O5)组成的V2O5/AC催化剂的低温脱硝活性的影响。发现在V2O5/AC催化剂表面负载碱金属化合物(K2SO4)后其脱硝活性大大降低。用等体积浸渍法制备了V2O5/AC催化剂和Kx-V2/AC(x=0.5,1,2)催化剂。采用5种模型对动力学实验数据进行关联。结果显示,无论V2O5/AC催化剂是否负载K2SO4,Eley-Rideal模型均比其他模型可更好地描述SCR脱硝反应,碱金属化合物(K2SO4)的存在提高了反应活化能,但并不改变反应机理。 相似文献
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8.
采用超音速电弧喷涂在Super304H不锈钢表面制备了45CT涂层,然后用含SiO2和硅酸盐的搪瓷粉对其进行封孔,研究了有无封孔的涂层表面涂覆75%(质量分数)Na2SO4+25%(质量分数)NaCl盐膜后在700°C下的热腐蚀行为。通过X射线衍射仪、扫描电镜和能谱仪分析了高温腐蚀产物的成分、结构和形貌。结果发现45CT涂层在腐蚀过程中出现明显质量损失,表面生成了以富铁氧化物为外层,富铬氧化物为内层的双层氧化膜,腐蚀产物剥落严重。涂层/基体界面有明显裂纹,基体一侧发生了晶间腐蚀。搪瓷封孔层具有较高的热稳定性和较低的腐蚀速率,因此在熔盐中仅发生了轻微溶解,有效地提高了45CT涂层的抗热腐蚀性。 相似文献
9.
以MgSO4·7H2O和K2CO3为原料、PEG为结构导向剂,采用共沉淀法合成出轻质碳酸镁纤维,其废液为K2SO4/K2Mg(SO4)2溶液。通过XRD、SEM和TG-DTA对样品进行表征,探究了影响轻质碳酸镁组成和形貌的因素及活性碳酸镁纤维形成机理。结果表明:在室温,搅拌速率为300 rad·min-1、Mg SO4浓度为1.0 mol·L-1、Mg SO4与K2CO3摩尔比为1∶1.1、PEG添加量为MgSO4·7H2O质量的30%的条件下,可制备分散性良好、晶须平均长度约为15.89μm、直径0.97μm、长径比为16.38的轻质碳酸镁纤维。 相似文献
10.
采用固相反应法制备SiC多孔陶瓷,通过添加二元复合烧结助剂K2CO3和CaCO3与SiC在空气气氛下氧化生成的SiO2在较低温度下生成低共融相,促进SiC多孔陶瓷在1100℃-1200℃温度下烧成。研究烧成温度、K2CO3和CaCO3添加量对SiC多孔陶瓷的抗弯强度、显气孔率、气体渗透率、相组成和显微结构的影响。结果表明:当K2CO3和CaCO3添加量分别为1wt%和1wt%,在空气气氛下1100℃保温3h制备的样品综合性能较佳,抗弯强度为33.6MPa,显气孔率为36.3%,气体渗透率为728m3/(m2·h·KPa)。 相似文献
11.
Phase equilibria and thermodynamics have been used to determine compatabilities in the systems CaSO4-K2SO4 and K2SO4-CaCO3. In the CaSO4-K2SO4 system, a polymorphic inversion at 200°C is encountered in K2Ca2(SO4)3. Thermodynamic calculation of the reciprocal salt system K2SO4-CaCO3-CaSO4-K2CO3 discloses that the join K2SO4-CaCO3 constitutes a stable binary: experiments in flowing CO2 at 1 bar pressure confirm this. A noteworthy feature of the system is the solid solution of CaCO3 in K2SO4, reaching 20% mol % CaCO3. The eutectic, located at 880°C and 43 mol % CaCO3, is attainable without significant decomposition. The possible consequences to clinkering reactions are discussed. 相似文献
12.
J.M. Parera 《Catalysis Today》1992,15(3-4):481-490
The promotion of zirconia by SO42− is studied by percolating of zirconia with aqueous solutions of several sulfur compounds and several concentrations of H2SO4 as sources of sulfur. The presence of SO42− is necessary to have catalytic activity to isomerize n-butane and produces a great increase in the stability of the physical texture to thermal treatments. The more convenient solution is 1N H2SO4·S042−/ZrO2 has the greatest catalytic activity after calcination at 893 K, where the tetragonal phase of ZrO2 predominates. The catalytic activity was found proportional to the specific surface area and surface SO42− concentration. 相似文献
13.
The effect of SO2 on the degradation of polyester-coated galvanised steel at different relative humidities was investigated using electrochemical impedance spectroscopy. Measurements were performed on specimens which had been tested in an accelerated gaseous corrosion test. For this purpose the samples were subjected to SO2 gas for 16 days in atmospheric test cells with adjusted relative humidity (RH) from 60 to 100%. Subsequently, the impedance response of the coated material was measured and evaluated. The results indicated that the coating performance varies with RH. Thus, under condensing conditions, the organic coating and galvanised layer was totally removed, the impedance response being interpreted as the formation of an iron sulphide film on the surface. At lower RH, remarkably, the coating remained effectively intact with the coating resistance varying inversely with RH. This work is relevant to the application of such organic-coated products adjacent to combustion flues where high levels of SO2 occur in association with high humidity. 相似文献
14.
Shamsuddeen A. Haladu Saviour A. Umoren Shaikh A. Ali Moses M. Solomon Abdul-Rashid I. Mohammed 《中国化学工程学报》2019,27(4):965-978
A novel tetrapolymer(TP) consisting of carboxylate, sulphonate, phosphonate and sulfur dioxide based comonomers was synthesized using Butler cyclopoymerization technique. The synthesized tetrapolymer was characterized using FTIR,1 H-NMR,~(13)CNMR and elemental analysis. The performance of the tetrapolymer as a corrosion inhibitor for St37 carbon steel in 15% HCl and 15% H_2SO_4 acid media was assessed using electrochemical impedance spectroscopy(EIS), linear polarization resistance(LPR), potentiodynamic polarization(PDP) and electrochemical frequency modulation(EFM) techniques. The influence of addition of a small amount of KI on the corrosion inhibition efficiency of TP was also assessed. Results obtained showed that the tetrapolymer moderately inhibited the corrosion of St37 steel in the acid media with protection efficiency of 79.5% and 61.1% at the optimum concentration of 1000 mg·L~(-1) studied in HCl and H_2SO_4 media respectively. On addition of 5 mmol·L~(-1) KI to the optimum tetrapolymer concentration, the protection efficiency was upgraded to 90.6% and 93.5% in HCl and H_2SO_4 environment, respectively. The enhanced performance of the polymer in the presence of KI is due to synergistic action deduced from synergism parameter(S1) which was found to be greater than unity.The tetrapolymer afforded the corrosion inhibition of St37 steel in the acid media by virtue of adsorption of the polymer molecules on the steel surface which was confirmed by ATR-FTIR analysis of the adsorbed film extracted from the steel surface. TP + KI formed complex with St37 steel surface in H_2SO_4 solution but not in HCl solution. 相似文献
15.
The catalytic oxidation of sulfur dioxide to sulfur trioxide over several binary (MxOy/TiO2) and ternary (V2O5/MXOY/TiO2) supported metal oxide catalysts was systematically investigated. The supported metal oxide components were essentially 100% dispersed as surface metal oxide species, as confirmed by Raman spectroscopy characterization. The sulfur dioxide oxidation turnover frequencies of the binary catalysts were all within an order of magnitude (V2O5/TiO2>Fe2O3/TiO2>Re2O7/TiO2 CrO3/TiO2 Nb2O5/TiO2>MoO3/TiO2 WO3/TiO2). An exception was the K2O/TiO2 catalysts, which is essentially inactive for sulfur dioxide oxidation. With the exception of K2O, all of the surface metal oxide species present in the ternary catalysts (i.e., oxides of V, Fe, Re, Cr, Nb, Mo and W) can undergo redox cycles and oxidize SO2 to SO3. The turnover frequency for sulfur dioxide oxidation over all of these catalysts is approximately the same at both low and high surface coverages. This indicates that the mechanism of sulfur dioxide oxidation is not sensitive to the coordination of the surface metal oxide species. A comparison of the activities of the ternary catalysts with the corresponding binary catalysts suggests that the surface vanadium oxide and the additive surface metal oxide redox sites act independently without synergistic interactions. The V2O5/K2O/TiO2 catalyst showed a dramatic reduction in the catalytic activity in comparison to the unpromoted V2O5/TiO2 catalyst. The ability of K2O to significantly retard the redox potential of the surface vanadia species is primarily responsible for the lower catalytic activity of the ternary catalytic system. The fundamental insights generated from this research can potentially assist in the molecular design of the air pollution control catalysts: (1) the development of catalysts for low temperature oxidation of SO2 to SO3 during sulfuric acid manufacture (2) the design of efficient SCR DeNOx catalysts with minimal SO2 oxidation activity and (3) improvements in additives for the simultaneous oxidation/sorption of sulfur oxides in petroleum refinery operations. 相似文献
16.
加入适宜的催化剂可以提高气化反应速率,降低起始气化温度。为了研究不同阴离子(SO42-、CO32-、Cl-)盐对府谷煤热失重过程的影响,利用热重分析仪对负载了8种催化剂(K2CO3、K2SO4、KCl;Na2CO3、Na2SO4、NaCl;FeSO4、FeCl2)的煤样进行了CO2气化实验,其中每克府谷煤的K+、Na+、Fe2+负载量分别为0.001mol。同时采用升温动力学模型进行了数据拟合。实验结果表明:催化剂对煤与CO2的低温热解并无明显的催化作用,而在高温气化阶段催化效果显著。对于钾盐和钠盐催化剂,当阳离子相同时,其催化活性顺序为:CO32->SO42->Cl-。对于铁盐催化剂,FeSO4的催化活性优于FeCl2。动力学结果发现:负载催化剂煤样的活化能大小符合上述实验规律,分布在169~232.6kJ/mol之间,相比原煤(267.9kJ/mol)都有一定程度的降低。 相似文献
17.
换热器微生物污垢问题普遍存在于能源化工领域,污垢的聚集会导致设备的流动阻力、燃料消耗和维护成本支出大幅度增加。本文采用复合纳米镀层来抑制和减轻换热表面的微生物污垢的附着和沉积。首先采用化学镀的方式,在板式换热器的不锈钢316板上镀覆 Ni-P-TiO2复合纳米镀层和对照性的Ni-P 镀层。基于板式换热器的微生物污垢在线监测实验系统,研究了镀覆Ni-P-TiO2复合纳米镀层的板式换热器微生物污垢特性。结果表明,清洁状态下,镀覆两种镀层的板式换热器其摩擦系数(f)和Nusselt数(Nu)相较未镀覆板式换热器均略有增加;微生物污垢实验后,相比较未镀覆的板式换热器,镀覆Ni-P镀层的板式换热器污垢热阻减少了8.36%~23.07%,而镀覆Ni-P-TiO2复合纳米镀层的板式换热器污垢热阻减少了16.6%~30.96%;在相同微生物污垢实验工况下,镀覆Ni-P-TiO2复合纳米镀层的板式换热器的摩擦系数(f)相比Ni-P镀层的低2.54%~11.82%,但Nu却明显高于Ni-P镀层达8.47%~9.45%,并且污垢热阻明显小于Ni-P镀层达10.66%~18.18%,镀覆Ni-P-TiO2复合纳米镀层的板式换热器展现了优异的强化传热性能和抑垢性能。 相似文献
18.
Manganese leaching during high concentration flue gas desulfurization process with semi-oxidized manganese ore was studied in this paper. It was found that there were different reaction pathways among which MnO_2,Mn_2O_3 and MnCO_3 in semi-oxidized manganese ore during flue gas desulphurization and manganese leaching.High SO_2 concentration facilitated redox reaction between MnO_2 and SO_2, and high concentration of H_2SO_4 accelerated MnCO_3/Mn_2O_3 leaching from semi-oxidized ore. Kinetics study showed that manganese leaching in flue gas desulfurization process with semi-oxidized ore was controlled by a mixed-control model, that is the surface chemical reaction and mass diffusion dominated both the oxidation of SO_2 and manganese leaching process. The apparent activation energy was 13.05 k J·mol~(-1) and the reaction orders with respect to SO_2 and H_2SO_4 concentration were 1.38 and 0.10, respectively. Finally, a semi-empirical rate equation based on shrinking core model was derived to describe the process. 相似文献