延迟焦化炉内湍流燃烧和炉管表面温度、热流分布

准确描述出炉膛内湍流燃烧过程,进而获得炉管表面温度和热流的分布情况,对焦化炉结构优化和防止管内结焦具有重要意叉.本文采用数值模拟方法,实现了对工业焦化炉包括燃烧器群、炉膛、炉管整体的,流动,燃烧和传热全部工艺过程的全尺寸耦合计算.计算得到了炉内温度以及炉管表面温度、热流分布的详细信息,揭示了焦化炉内燃烧和传热过程的基本特性.     

基于热辐射成像建模求解的管式炉炉管温度检测

准确在线检测管壁表面分布式温度是优化管式炉加热工艺的关键所在。以一台工业管式裂解炉为试验对象,结合辐射图像处理方法,开展了管式炉炉管表面温度可视化检测研究。采用基于Monte Carlo的DRESOR法求解具有复杂边界条件的管式炉辐射成像模型,实现了炉管辐射与火焰辐射、炉壁辐射的解耦计算,对炉管表面温度与热通量分布进行了在线监测,并研究了二者随工质流动方向的变化趋势。经过验证,温度测量误差小于2%,测量误差主要出现在最高和最低温区域。该项研究将有助于指导管式炉燃烧调整,改进加热工艺,提高炉管表面受热均匀性,延长炉管工作寿命。     

一段转化炉炉管弯曲变形原因分析及预防措施

中国石油天然气股份有限公司塔里木油田石化分公司450kt/a合成氨装置2014年起发现一段炉炉管开始弯曲变形及颜色变亮,且一段炉出口气甲烷含量逐年升高,2015年更换一段炉转化催化剂,2018年时一段炉炉管弯曲变形等情况更加严重,2019年初部分一段炉炉管出现热斑,炉管表面温度接近或超过设计温度.2019年冬季装置停车...     

减压炉烧焦工艺及效果

为解决洛阳石化分公司减压炉炉管结焦问题,在2017年11月的装置停工检修中对减压炉进行烧焦处理。通过烧焦,结焦炉管压降明显降低,传热效率明显提高。经过现场测温,炉管表面温度明显降低,烧焦取得较大成效。通过本次烧焦,保证了减压炉正常运行,提高了减压炉出口温度,为减压深拔做出了重要贡献。     

裂解炉炉管温度实时在线监测与分析

为了实时准确获取裂解炉炉管表面真实温度,介绍了一种基于近红外比色测温技术的炉管表面温度实时在线监测系统。论述了系统器件校准和环境背景影响消除的原理和方法,并通过一次和二次补偿因子校准使系统测量误差达到测量值的±0.5%或±5℃。系统应用于裂解炉取得了炉管实时监测及运行历史数据。结果表明:该系统可实时准确获取炉管表面真实温度,分析炉管表面温度分布特性,跟踪炉管温度运行历史,预测炉管运行周期,为加热炉安全稳定运行提供保障,实现节能降耗及效益提升。     

用蒙特卡罗法计算制氢转化炉辐射室温度分布

采用蒙特卡罗方法对制氢转化炉辐射室、炉管以及烟气的温度进行计算。和实际测量结果比较表明 ,模拟计算结果较好地反映了辐射室的温度分布情况。通过计算炉管温度分布 ,有助于研究制氢转化炉炉管弯曲的机理     

管壁温度的测量与几何因子的计算

在使用高温计测量炉管表面温度时,反射辐射对测量的影响颇为严重,必须加以修正.几何因子是作这种反射修正的关键数据.本文提出一种计算几何因子的方法,同时计算了Topsφe转化炉和Lummus裂解炉的几何因子,并与某公司的推荐数值和实验数据作了比较.结果表明计算值与推荐值相当一致,光学高温计的测得值用作者推荐的几何因子作反射修正后与铠装热电偶测得值很接近.     

新旧HP.Nb炉管焊接后剩余寿命评价

制氢转化炉在石化行业中应用广泛,作为关键设备的转化炉炉管,由于服役温度高,一般采用离心铸造的HK40或HP.Nb高温合金。当制氢转化炉炉管发生局部失效时,采用局部更换炉管方法可延长整根炉管的使用寿命。文中分别采用微观组织分级法、基于硬度测量的寿命预测方法以及Larson-Miller参数法对新旧HP.Nb炉管焊接后的寿命进行综合评价,研究结果表明新旧炉管焊接后的剩余寿命约为4.5×104h,蠕变断裂发生在旧母材处。     

关于大型氨厂蒸汽——烃转化炉管的寿命问题

一、转化炉运转情况的判断目前,国外大型氨厂,对蒸汽——烃转化炉的运转情况,比较主观意断。最近,美国触媒和化学试剂公司(CCI)曾进行试验,对管壁温度进行了实测和设计估算,发现其差值超过16.6℃就需要更换触媒。工业上曾采用多种方法来判断炉管运转情况以避免过早的更换炉管或不必要的停产。为了全面说明转化炉运转情况,首先需对炉管内流量、温度、压力和气体组份进行测量,测量布     

一段炉炉管提高操作温度的可行性分析及炉管剩余寿命预测

中海石油富岛有限公司一期合成氨装置一段炉于1996年投用,其炉管分别于2005年12月和2009年12月进行过2次更换;2018年3月更换了转化催化剂后,2019年初部分炉管出现热斑,炉管表面温度已接近或超过设计温度。为确保炉管的安全、稳定运行,利用拉森-米勒(L-M)曲线反推法,对使用寿命为10×10~4 h的炉管在各种操作温度下所需的实际壁厚进行计算,并通过拉森-米勒(L-M)曲线参数公式推导出各操作温度下炉管的理论使用寿命。计算结果表明:理论上一段炉炉管在现有的操作条件下(压力3.9 MPa、温度893℃以下)长期使用是可行的,即使炉管实际操作温度提高到920℃,炉管强度仍能满足使用要求;但由于炉管已处于使用寿命的中后期,宜采用一些延长炉管服役周期的措施,即需精心操作、合理地控制工艺参数,才有可能确保炉管剩余寿命期内的安全、稳定运行。     

高效液相色谱法测定小麦粉及面粉处理剂中三聚硫氰酸三钠盐的含量

建立了小麦粉及面粉处理剂中三聚硫氰酸三钠盐的高效液相色谱(HPLC)检测方法。对比了不同提取试剂及提取方式对三聚硫氰酸三钠盐回收率的影响,并考察了三聚硫氰酸三钠盐在样品提取液中的稳定性。在最优实验条件下,三聚硫氰酸三钠盐在浓度0.05~2.0μg/mL范围内线性良好,相关系数R2=1.000 0,方法检出限为0.4 mg/kg,定量限为1.0 mg/kg。小麦粉中三聚硫氰酸三钠盐的加标回收率为80.4%~84.8%,RSD为1.4%~3.1%;面粉处理剂中三聚硫氰酸三钠盐的加标回收率为87.9%~91.5%,RSD为2.2%~3.2%。     

Recovery of Silver from X-Ray Film Processing Effluents Using Trimercapto-s-triazine (TMT)

In this study, the recovery of silver from waste X-ray photographic solutions by precipitation using trimercapto-s-triazine (TMT) was studied. Taguchi L₂₅ (5³) orthogonal design was adopted for the study. The effects of concentration of thiosulphate (5.2–200 g/L), TMT (Ag:TMT = 6.6–2.2), temperature (20–60°C) and pH (4.37–8.00) on the extent of the precipitation of silver were investigated. The findings have shown that the concentration of TMT and pH are the most significant factors affecting the recovery of silver while the effect of temperature (20–60°C) is insignificant under the conditions tested. The increase in the concentration of TMT and pH was found to improve the extent of precipitation of silver. TMT was also found to be an effective agent to reduce silver concentrations below the regulatory limit value of 5 ppm. Characterization of the precipitates was performed to identify silver-TMT compounds formed.     

Synthesis and characterisation of branched and partially crosslinked poly(ethylene terephthalate)

In the present study, a series of branched and partially crosslinked poly(ethylene terephthalate) (PET) samples were prepared by the two‐stage melt polycondensation method, using different amounts of trimethyl trimellitate (TMT) as polyfunctional monomer. The samples were characterised with respect to intrinsic viscosity, density and gel content as well as thermal and mechanical properties. The intrinsic viscosity of the polymers ranged between 0.7 and 1.6 dl g^?1 depending on the concentration of the TMT comonomer. When TMT was used at a concentration 0.625 wt% or higher, gel formation was observed. For the sample containing 1.25 wt% TMT, almost half of the polymer was insoluble in phenol–tetrachloroethane mixture, due to extensive crosslinking. The increase of TMT content resulted in a small decrease of crystallinity attributed to branching and crosslinking, both of which restrict the organisation of the polymer chains in the crystal structure. This was reflected directly in the thermal properties of the polymers prepared. Increasing the TMT content decreased the melting point and the heat of fusion. In contrast, cold crystallization and glass transition temperatures were shifted to higher temperatures. Mechanical properties like tensile strength and elongation at break increased with increasing the content in branching agent. However, crosslinking had a negative effect on elongation at break. Copyright © 2003 Society of Chemical Industry     

Synthesis and Characterization of Novel Polyol Esters of Undecylenic Acid As Ecofriendly Lubricants

Three novel esters of undecylenic acid (UA) were synthesized using the following polyols: linear diglycerol (DG), pentaerythritol monomethylether (PEME), and trimethyloltoluene (TMT). They were characterized through density, viscosity, thermo-oxidative stability, melting point (m.p.), miscibility with mineral oils, and toxicity to evaluate their potential as ecofriendly lubricants. Trimethylolpropane (TMP) triundecylenate was also synthesized and characterized as a reference ester. Esters’ densities were in the range 0.93–0.97 g cm⁻³. The PEME ester showed a kinematic viscosity of 25.2 cSt at 40°C, only slightly higher than that of TMP ester (24.7 cSt), both of them near the ISO VG 22 class, while DG and TMT esters were near the ISO VG 32 class, with viscosities of 28.3 and 37.1 cSt, respectively. PEME and TMT esters were similar in thermo-oxidative stability and more stable than their corresponding oleate esters. The m.p. of TMT ester was remarkedly low (−54°C), showing its potential for very cold temperature applications. TMT ester was found to be nontoxic against Artemia salina (LC₅₀ > 1000 μg mL⁻¹), an initial indication of nontoxicity of UA esters in aquatic media. The synthesized esters showed potential to be applied as ecofriendly lubricants.     

Prenatal Trimethyltin Exposure Induces Long-Term DNA Methylation Changes in the Male Mouse Hippocampus

Trimethyltin (TMT) is an irreversible neurotoxicant. Because prenatal TMT exposure has been reported to induce behavioral changes, this study was conducted to observe gender differences and epigenetic changes using a mouse model. In behavioral testing of offspring at 5 weeks of age, the total times spent in the center, corner, or border zones in the male prenatal TMT-exposed mice were less than those of control unexposed mice in the open-field test. Female TMT-exposed mice scored lower on total numbers of arm entries and percentages of alternations than controls in the Y-maze test with lower body weight. We found that only TMT-exposed males had fewer copies of mtDNA in the hippocampus and prefrontal cortex region than controls. Additional epigenetic changes, including increased 5-methyl cytosine/5-hydroxymethyl cytosine levels in the male TMT hippocampus, were observed. After methylation binding domain (MBD) sequencing, multiple signaling pathways related to metabolism and neurodevelopment, including FoxO signaling, were identified by pathway analysis for differentially methylated regions (DMRs). Increased FOXO3 and decreased ASCL1 expression were also observed in male TMT hippocampi. This study suggests that sex differences and epigenetics should be more carefully considered in prenatal toxicology studies.     

钯/碳催化的3,4,5-三甲氧基苯甲醛还原反应

引　言3,4 ,5 -三甲氧基苯甲醛 (ＴＭＢ)是以对甲酚为原料开发的重要的有机合成中间体[1] ,由其出发可以合成 3,4 ,5 -三甲氧基苯甲酸、 3,4 ,5 -三甲氧基苯甲醇、 3,4 ,5 -三甲氧基甲苯 (ＴＭＴ)、 3,4 ,5 -三甲氧基苯酚等高附加产值的精细化工产品 .ＴＭＢ进行还原反应是合成其下游产品的重要途径 ,但对于ＴＭＢ氢化还原反应的研究尚无文献报道 ,因此开展此项研究对于揭示反应过程 ,开拓应用领域具有重要意义 .1　实验部分1.1　还原反应的一般步骤1.1.1　Ｐｄ/Ｃ -ＴＭＢ -Ｈ2 -ＡｃＯＨ反应体系　将4 .9ｇ (0 .0 2 5ｍｏｌ)ＴＭＢ置于 5 …     

Field Testing Synthetic Predator Odors for Roof Rats (Rattus Rattus) in Hawaiian Macadamia Nut Orchards

Field trials were conducted to determine whether the synthetic predator odors 3,3-dimethyl-l,2-dithiolane (DMDIT) and (E,Z)-2,4,5-tri-methyl-³-thiazoline (TMT) were effective at eliciting a behavioral response in wild roof rats (Rattus rattus). The study site was a Hawaiian macadamia nut (Macadamia integrifotia) orchard with a recent history of roof rat feeding damage. The synthetic predator odors were encapsulated in urethane devices secured to tree branches. Mark-recapture data from live-trapping of rats and radio telemetry location data were used to assess behavioral responses of rats to the predator odors. Mark–recapture data indicated that DMDIT and TMT had no effect on capture numbers, reproduction, or body weight of rats. There was some indication that distribution of captures and number of locations relative to treated trees in TMT areas were less than in controls, but this pattern was not significant. The predator odors had no effect on home range or median distance from center of activity (MDIS) of rats as measured by telemetry. There was a trend of increasing values of MDIS on TMT areas in session 1 but not session 2. Overall we could not detect significant differences or consistent trends in responses of rats to DMDIT or TMT in these field trials.     

Therapeutic Effects of Hydrogen Gas Inhalation on Trimethyltin-Induced Neurotoxicity and Cognitive Impairment in the C57BL/6 Mice Model

Oxidative stress (OS) is one of the causative factors in the pathogenesis of various neurodegenerative diseases, including Alzheimer’s disease (AD) and cognitive dysfunction. In the present study, we investigated the effects of hydrogen (H₂) gas inhalation in trimethyltin (TMT)-induced neurotoxicity and cognitive dysfunction in the C57BL/6 mice. First, mice were divided into the following groups: mice without TMT injection (NC), TMT-only injection group (TMT only), TMT injection + lithium chloride-treated group as a positive control (PC), and TMT injection + 2% H₂ inhalation-treated group (H₂). The TMT injection groups were administered a single dosage of intraperitoneal TMT injection (2.6 mg/kg body weight) and the H₂ group was treated with 2% H₂ for 30 min once a day for four weeks. Additionally, a behavioral test was performed with Y-maze to test the cognitive abilities of the mice. Furthermore, multiple OS- and AD-related biomarkers such as reactive oxygen species (ROS), nitric oxide (NO), calcium (Ca²⁺), malondialdehyde (MDA), glutathione peroxidase (GPx), catalase, inflammatory cytokines, apolipoprotein E (Apo-E), amyloid β (Aβ)-40, phospho-tau (p-tau), Bcl-2, and Bcl-2- associated X (Bax) were investigated in the blood and brain. Our results demonstrated that TMT exposure alters seizure and spatial recognition memory. However, after H₂ treatment, memory deficits were ameliorated. H₂ treatment also decreased AD-related biomarkers, such as Apo-E, Aβ-40, p-tau, and Bax and OS markers such as ROS, NO, Ca²⁺, and MDA in both serum and brain. In contrast, catalase and GPx activities were significantly increased in the TMT-only group and decreased after H₂ gas treatment in serum and brain. In addition, inflammatory cytokines such as granulocyte colony-stimulating factors (G-CSF), interleukin (IL)-6, and tumor necrosis factor alpha (TNF-α) were found to be significantly decreased after H₂ treatment in both serum and brain lysates. In contrast, Bcl-2 and vascular endothelial growth factor (VEGF) expression levels were found to be enhanced after H₂ treatment. Taken together, our results demonstrated that 2% H₂ gas inhalation in TMT-treated mice exhibits memory enhancing activity and decreases the AD, OS, and inflammatory-related markers. Therefore, H₂ might be a candidate for repairing neurodegenerative diseases with cognitive dysfunction. However, further mechanistic studies are needed to fully clarify the effects of H₂ inhalation on TMT-induced neurotoxicity and cognitive dysfunction.     

Novel color stabilization concepts for decorative surfaces of native dark wood and thermally modified timber

UV and visible light exposure of dark colored wood and thermally modified timber (TMT) is strongly connected with discoloration and photobleaching of the respective wood surfaces. Conventional and nanoscale UV absorbers as well as radical scavengers (HALS), mainly effective for the protection of softwood and bright hardwood, were found to be improper for the light stabilization of dark wood surfaces. In the current work discoloration mechanisms are discussed considering the role of wood extractives and the sensitivity of dark colored wood types to visible light and results are presented which were obtained by applying novel protecting systems for the light stabilization of transparently coated surfaces from dark colored wood types and TMT.     

2,3-二甲氧基-5-甲基-1,4-苯醌的合成

以3,4,5-三甲氧基甲苯(TMT)为原料,先由V ilsm e ier-Haack反应合成6-甲基-2,3,4-三甲氧基苯甲醛,然后在对甲基苯磺酸催化下经Dak in反应将其氧化为6-甲基-2,3,4-三甲氧基苯酚,最后用重铬酸钠催化氧化合成了辅酶Q0,过程总收率达到72.3%。经正交实验得V ilsm e ier-Haack反应的最佳工艺为:n(TMT)∶n(POC l3)∶n(DMF)=1∶1.8∶2.2,反应温度70℃,反应时间7 h。在此工艺条件下,此步反应收率可达93.2%,w(6-甲基-2,3,4-三甲氧基苯甲醛)=98.5%;在Dakin反应中,以w(H2O2)=30%为氧化剂,30℃为最佳反应温度,反应时间1.5 h。