基于VSP2的放热反应失控紧急泄放特性

基于VSP2绝热量热仪,通过增加泄放物收集罐、快速响应气动阀及泄放孔板,开展了放热反应失控泄放实验,详细探讨了输入热功率、初始填充率、泄放压力、泄放直径以及反应物发泡性对泄放能力及泄放物质量的影响。结果表明:二相流泄放能力随输入热功率增大而降低,随初始填充率增大先增大后减小,随泄放压力增大先快速降低后缓慢增加,随泄放直径增大而增大。泄放物质量随输入热功率、初始填充率、泄放压力和泄放直径的增大而增大。发泡性材料能显著降低泄放装置的泄放能力,但能增大泄放物质量。     

反应热失控条件下安全泄放实验与理论计算

反应热失控是引起设备超压的重要因素之一,而安全可靠的安全泄放装置是防止设备发生超压破坏的最有效方法。由于苯法制己内酰胺重排反应是个快速的强放热过程,为了对重排反应器的安全泄放设计提供基础数据,在危险场景分析基础上,利用引进的VSP2(Vent Sizing Package 2)安全泄放实验装置进行了热失控反应条件下泄放实验研究。实验表明失控反应条件下重排反应泄放类型为温和体系的蒸气泄放,因而利用Leung方法和平衡两相流泄放模型分别对安全泄放量(W)和泄放装置泄放能力(G)进行了计算,进而确定出最小泄放面积为0.023m2。研究表明:利用VSP2可为快速强放热的失控反应安全泄放设计提供基础数据,进而为失控反应安全泄放设计的安全可靠性提供保证。     

基于VSP2进行热失控反应泄放装置安全可靠性分析与评估

为了对存在热失控危险的反应器的安全泄放装置安全可靠性进行分析和评估,利用从美国购置的用于泄放基础实验测试的VSP2(Vent Sizing Package 2)装置,针对不同的危险场景,对苯法制己内酰胺组合工艺中重排反应器的热失控反应过程进行了实验测试,筛选出最危险场景。在获得重排反应热失控基础数据条件下,对安全泄放量(W)和泄放装置泄放能力(G)进行了计算,进而获得最小安全泄放面积。研究表明:重排反应过程是个强放热过程,存在较大的热失控风险;利用VSP2可为存在热失控危险反应的安全泄放设计提供基础实验数据,进而对安全泄放装置设计、选型或安全可靠性分析和评估提供技术支持。     

浅谈压力容器安全泄放装置的选用

介绍了压力容器安全泄放装置的分类、作用和选用原则。     

常压储罐的安全泄放设施设计

从常压储罐的呼吸阀和气封系统设计方面,简要介绍储罐的安全泄放设施设计选用的主要原则和计算方法。     

环氧乙烷储罐安全泄放工艺系统设计

由于环氧乙烷的特殊物性和环保安全要求,工程设计上做到环氧乙烷储罐安全泄放尤为重要。本文从环氧乙烷储罐安全泄放的工艺系统角度,详细研究和论证了目前环氧乙烷储罐安全泄放的工艺系统,提出一种切实可行、安全有效的环氧乙烷储罐安全泄放工艺系统     

粉尘爆炸的泄放设计

讨论粉尘爆炸泄放、泄放面积的确定、泄放压力下容器强度以及爆炸泄放装置在容器上的配置等问题。给出了计算实例。     

移动式压力容器安全泄放装置的计算

阐述了移动式压力容器安全泄放装置的计算方法和步骤。     

间歇与半间歇反应热失控危险性评估方法

针对间歇、半间歇反应器中频繁更换物系和/或反应工艺,受时间和经济条件限制往往不可能对发生在其中的反应动力学进行深入研究的特点,建立适用于它们的热失控危险评估方法具有重要意义。本文对此做了简要的综述并且认为,尽管迄今还没有普适性的方法,但是对于某些类型的重要反应,安全界限图方法和反应失控情景分析方法还是较为适用的。前者虽然涉及参数较多,且没有考虑高温下物料二次分解的可能性,但能按照反应结果将量纲1操作参数平面划分为无积累、反应失控、未充分引发及无害4个子区域,从而可以先验地获取更多的信息;后者虽然忽略了均相与非均相反应的不同,但该方法可对一定工艺条件下目标反应失控和二次分解反应进行分析评估,简单易行,考虑更全面。     

Inherently safer reactors and procedures to prevent reaction runaway

Reaction runaway has longtime been an issue in chemical industry as it often leads to severe accidents if not controlled and inhibited properly. Herein we have reviewed several key considerations and procedures to prevent such phenomena, including inherently safer reactor design, thermal risk assessment and early warning detection of runaway, and pointed out that the basic principle underlying is necessary heat management and construction of resilient processes. For inherently safer reactor design, important factors such as heat removal, heat capacitance, flow behaviors and explosive behaviors have been investigated. The survey shows that heat exchanger (HEX) reactor and microreactor outperform traditional reactors. Meanwhile, we have looked into the effect of thermal risk ranking and safety operation region determining for thermal risk assessment, and the influence of runaway criteria and construction methods for early detection of reaction runaway as well. It shows that thermal risk assessment plays a key role on process design, and early warning detection system (EWDS) is preferable on prevention of reaction runaway. In the end, perspectives regarding inherently safer designs with the measures discussed above have been provided.     

化学放热系统热失控临界判据的研究进展

化工过程安全是绿色化工的主要研究内容之一。研究化学放热系统热失控临界判据,实质上就是确定反应系统安全操作区域,避免热失控行为的发生。本文对热失控临界判据进行了详细总结,对各判据的优缺点进行了分析比较,提出了临界判据有效性的判定方法。最后,对非线性科学在放热系统热失控领域的研究进行了展望。     

甲基叔丁基醚装置催化剂床层“飞温”原因分析及控制

针对中国石油大连石化公司甲基叔丁基醚(MTBE)装置2010年开工过程中催化蒸馏塔出现的床层飞温现象进行分析讨论。阐述了造成床层飞温的因素及应对措施,提高装置运行和开停工过程操作平稳率,延长催化剂使用寿命。     

冷喂料排气挤出机的设计原理

本文应用粘性流体输送理论．介绍了冷喂料排气挤出机的排气原理和结构特点，讨论了稳定挤出的必要条件，分析了螺杆参数选择的原则．提出了提高排气效率的途径。     

搅拌槽中酯化反应热失控的CFD模拟

热失控是化工过程中常见的安全风险之一。在间歇釜式反应器中,桨叶的机械转动可以增强流体的循环流动、湍流强度、混合程度以及传热,进而有效防范热失控。防控效果与反应器结构和搅拌桨型密切相关。针对丙酸异丙酯酯化反应,采用计算流体力学模拟研究了桨型(Rushton桨、30o PBT桨及60o PBT桨)、转动方向和挡板对釜式反应器内温度演化的影响,从流动结构方面分析了原因。基于散度的失控判据比较了三种搅拌桨抑制热失控的能力,抑制能力为Rushton桨＞30° PBTD桨＞60° PBTD桨。本研究可为搅拌反应器热失控的优化设计提供一定的理论依据。     

Shortstopping and jet mixers in preventing runaway reactions

Runaway reactions are continuing to be a major problem in the chemical industry (26% of major accidents). One of the main reasons for runaways is power failure. Runaway reactions could be inhibited in two ways: by the addition of cold diluents and by the addition of an inhibitor (chemical reaction stopper). This technology is called shortstopping. After a power failure, the process of adding an inhibiting agent and mixing it with the reactor contents becomes a major problem in the shortstopping process. Jets or impellers, driven by a small generator, however, can be used for mixing the inhibitor with the reactor contents.Dakshinamoorthy et al. [2006. CFD simulations of shortstopping runaway reactions in vessels agitated with impellers and jets. Journal of Loss Prevention in the Process Industries 19, 570-581] compared the efficiency of using jet mixers versus impeller stirred vessels in shortstopping runaway reactions. On the basis of equal power consumption, this comparative study showed that jet mixers are ineffective when used for shortstopping. One needs to identify additional factors, to effectively shortstop when using jet mixers.Due to the hazardous nature of runaway reactions, these factors cannot be determined with lab scale or pilot plant scale experiments. Recent developments with CFD make it possible to carry out virtual experiments. The computational model is solved using FLUENT. Shortstopping studies via the addition of a reaction inhibitor and cold diluent are discussed in detail. The results reported in this study identify the major and minor factors, which contribute to effective shortstopping; i.e., power requirements, locations for adding the inhibitor, the quantity of inhibitor added, rate of the inhibition, the use of cold diluent and the use of multiple nozzles. These results especially demonstrate the value of using CFD simulations in situations that are experimentally prohibitive.     

基于绝热加速量热测试的过氧化叔丁基反应失控的泄放设计(英文)

In order to design the relief system size of di-tert-butyl peroxide(DTBP) storage tanks,the runaway re-action of DTBP was simulated by accelerating rate calorimeter(ARC).The results indicated that under adiabatic conditions the initial exothermic temperature was 102.6 ℃,the maximum self-heating rate was 3.095×107 ℃·min-1,the maximum self-heating temperature was 375.9 ℃,and the pressure produced by unit mass was 4.512 MPa·g-1.Judged by ARC test,the emergency relief system for DTBP was a hybrid system.Based on Design Institute for Emergency Relief System(DIERS) method,the releasing mass flow rate W was determined by Leung methods,and the mass velocity G was calculated by two modified Omega methods.The two relief sizes calculated by monograph Omega method and arithmetic Omega method are close,with only 0.63% relative error.The monograph Omega method is more convenient to apply.     

铁锈对环氧乙烷水溶液失控反应的影响

采用绝热量热仪对环氧乙烷(EO)水溶液?铁锈/Fe2O3体系进行了绝热量热实验,得到了铁锈、Fe2O3固体与EO水溶液接触时的起始放热温度、最高放热温度和压力、绝热温升、失控反应过程温度、压力等参数. 结果表明,在实验条件下EO水溶液与现场铁锈接触时失控反应特征不明显,未出现温度、压力剧升现象;发生失控反应的起始放热温度、最高反应温度、最高压力等随EO浓度降低而减小,达到最大反应速率的时间在30 min内,30wt% EO水溶液?Fe2O3体系的起始放热温度接近100℃,纯EO?Fe2O3体系的起始放热温度为150℃. Fe2O3固体比现场铁锈对EO及其水溶液失控反应的催化诱导作用更明显,且随EO浓度升高,失控后果更严重.     

泄压条件下管道内瓦斯爆炸传播的氮气阻爆

矿井瓦斯爆炸发生后,采用灭火剂进行阻爆,将有助于从根本上消除爆炸的灾难性后果。本文在爆炸管道上设置双喷头,探索喷出N₂来实现阻爆和熄灭火焰。对于四周保持密闭的平直管道,采用不同压力将氮气喷出,但均未能阻止爆炸火焰沿管道的传播。在管道下表面设置开口进行泄压后,可以观测到爆炸过程中大量的高温气团和预混气从该开口流出,并在开口外继续发生反应。结合侧向泄压,当双喷头中左喷头（第二喷头）不喷N₂时,右喷头（第一喷头）所喷N₂在各个压力下也仍未能实现阻爆。但当左喷头（第二个喷头）压力在0.1 MPa及以上时,均能实现阻爆。并且双喷头所喷N₂压力越大,爆炸火焰被阻止和熄灭的位置越靠前。通过侧向泄压使管道内的反应变弱是有利于阻爆的第一个主要原因。侧向泄压使管道内爆炸火焰的传播速度下降,从而喷出更多氮气并获得更长的时间来对预混气进行充分稀释,这是实现阻爆和熄灭火焰的第二个主要原因。