共查询到19条相似文献,搜索用时 406 毫秒
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《石油机械》2019,(12):131-138
节流阀在现场使用中,时常有阀芯断裂失效的情况发生,对油气的稳定可靠生产造成了不利影响。鉴于此,借助CAD及有限元软件建立了节流阀的力学模型,对其在不同工作压力中的阀芯受力进行了分析研究,并基于研究成果对节流阀的阀芯结构进行了一定改进。研究结果表明:阀芯在安装及使用中,在阀芯台肩及阀芯销孔处一直存在较大的拉应力,但拉应力始终小于阀芯材料的许用应力,阀芯的失效形式为低应力下的断裂损坏;通过增加台肩的倒圆半径以及合理的设计销孔位置能够在一定程度上降低阀芯拉应力,大幅延长节流阀的使用寿命。研究结果可为节流阀及其他类似阀芯的结构优化设计提供一定的理论参考。 相似文献
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马忠学 《石油化工设备技术》2002,23(2):19-20,26
通过对往复式高压注水泵进出口单向阀阀杆频繁断裂的失效分析 ,经计算 ,从单向阀的结构和设计上进行了局部改进 ,大大提高了阀的使用寿命 相似文献
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一、问题的提出目前催化油浆的流量控制仍延用经典的角型调节阀。在实际应用中该阀的主要问题,一是抗磨性差。尽管阀芯、阀座堆焊硬质合金也只能维持数月时间。二是该种阀稳定性差。由于角型阀是一种单阀芯柱塞结构,在实际运行中作用在阀芯上的不平衡力较大,特别 相似文献
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针对齐鲁Texaco煤气化锁渣阀的使用条件、结构特点和运行工况,对其在应用中常见的故障进行了原因分析;从阀内件的维修工艺、阀球阀杆的连接方式、执行机构的运行条件以及锁渣阀的运行工况等方面提出了延长锁渣阀使用寿命的改进措施;介绍了目前锁渣阀国产化应用方面的改进情况。 相似文献
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阀内件磨损程度直接关系到阀门的性能,特别是苛刻工况下阀内件的磨损尤其严重。全面地分析阀内件磨损形成的原因,并从阀内件的材料性能出发,论述了不同阀内件材质的性能和硬化处理方法,重点探讨了在苛刻工况下的阀内件材质的选择。事实表明,在选择好阀芯形式的基础上,通过合理地选择阀内件的材质,可以有效地减少阀内件的磨损,从而延长阀门的使用寿命、提高阀门的使用性能。 相似文献
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某炼化公司1.00 Mt/a乙烯工程的调温水冷却器循环水氯离子质量分数高达100~700 μg/g,对板片的腐蚀性强,所以板片的选材最为关键.分析了不锈钢的耐腐蚀原理、氯离子对不锈钢的破坏;AISI 304L,AISI 316L,SAF 2205,SAF 2304,SAF 2507,SMO 254六种不锈钢的化学成分、机械性能、抗氯化物腐蚀性能.根据温度、氯离子含量以及pH值等因素,决定采用SMO 254不锈钢板片. 相似文献
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《Food Control》2017
The N60 method currently mandated by regulatory bodies in North America for routine testing of beef trim for Escherichia coli O157:H7 requires that 60 slices of beef, up to 375 g, be removed from combo bins containing up to 10,000 lb of beef trim. The objective of this study was to design and test a prototype automatic trim sampler that would reduce the resource demands of, and result in more representative sampling than, N60. Ten commercial combo bins were each sampled at five locations of each of four levels, by swabbing an area of 1000 cm2 and by excision of up to five meat pieces with a total area of 100 cm2. The samples were enriched in modified Tryptone Soy Broth supplemented with novobiocin at 20 mg/L, and tested for generic E. coli using real-time PCR. A prototype trim sampler was constructed and tested for recovery of aerobes, coliforms and E. coli and was compared to manual swabbing, using beef trim artificially contaminated with E. coli. Overall, 21.5% of excision samples and 38.0% of swab samples from combo bins were positive for E. coli. Of the 40 levels that were sampled, 50.0% were positive by excision, 70.0% were positive by swabbing. The sampler, designed based on swab sampling, could process trim of ≤1 kg. Of the 12 pairs of manual sampling and automatic sampling compared, ≥ 8 were not significantly different for recovering each of the three groups of indicator organisms (P > 0.05). The findings of this study show that swab sampling can be more sensitive and representative than excision sampling for recovering small numbers of E. coli from beef trim and the prototype sampler can have efficacy comparable to manual swabbing for recovering all three groups of indicator organisms from beef. 相似文献
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论述了陶瓷内件控制阀的研制,该阀内件同时具有耐腐蚀、耐磨损(包括冲刷、气蚀)与耐高温的性能。已获得成功应用。 相似文献
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《Food Control》2014
Beef trim, the primary component of ground beef, is tested by both the Food Safety and Inspection Service (FSIS) and meat packers for Escherichia coli O157:H7 under a zero tolerance standard. We compare and contrast the process control and filtering roles of this testing on costs and food safety outcomes. Both of these roles of testing have been alternatively emphasized in recent legislative proposals and policy statements on beef trim testing. In the process control role, test design – including the decisions to increase sample sizes, re-test lots, and change tolerance thresholds – only affects the cost of implementing a targeted food safety standard, but does not directly affect health outcomes. In contrast, in the filtering role, test design influences the likelihood of errors and directly affects health outcomes. Neither role eliminates all risk from this pathogen. More broadly, we discuss the incentives food producers face to increase their frequency of testing and improve food safety processes in response to positive test findings as the process control role emphasizes. 相似文献