氯气氯化工艺过程自动控制方案研究

在对大量涉及氯气氯化工艺的化工企业实际调查研究的基础上,结合众多化工安全专家的实践经验,提出液氯钢瓶称重装置、液氯气化装置、氯气缓冲装置、氯化反应装置和事故氯气吸收处理装置安全控制方案.液氯钢瓶称重装置对液氯钢瓶进行称重并设自动报警.液氯气化装置采用盘管式气化器,在蒸汽输入端设自动调节阀门,热水侧设温度显示报警装置等进...     

Evaluation of CFD simulations of transient pool fire burning rates

Fire is the most commonly occurring major accident hazard in the chemical and process industries, with industry accident statistics highlighting the liquid pool fire as the most frequent fire event. Modelling of such phenomena feeds heavily into industry risk assessment and consequence analyses. Traditional simple empirical equations cannot account for the full range of factors influencing pool fire behaviour or increasingly complex plant design. The use of Computational Fluid Dynamics (CFD) modelling enables a greater understanding of pool fire behaviour to be gained numerically and provides the capability to deal with complex scenarios.This paper presents an evaluation of the Fire Dynamics Simulator (FDS) for predictive modelling of liquid pool fire burning rates. Specifically, the work examines the ability of the model to predict temporal variations in the burning rate of open atmosphere pool fires. Fires ranging from 0.4 to 4 m in diameter, involving ethanol and a range of liquid hydrocarbons as fuels, are considered and comparisons of predicted fuel mass loss rates are compared to experimental measurements.The results show that the liquid pyrolysis sub-model in FDS gives consistent model performance for fully predictive modelling of liquid pool fire burning rates, particularly during quasi-steady burning. However, the model falls short of predicting the subtleties associated with each phase of the transient burning process, failing to reliably predict fuel mass loss rates during fire growth and extinction. The results suggest a range of model modifications which could lead to improved prediction of the transient fire growth and extinction phases of burning for liquid pool fires, specifically, investigation of: ignition modelling techniques for high boiling temperature liquid fuels; a combustion regime combining both infinite and finite-rate chemistry; a solution method which accounts for two- or three-dimensional heat conduction effects in the liquid-phase; alternative surrogate fuel compositions for multi-component hydrocarbon fuels; and modification of the solution procedure used at the liquid-gas interface during fire extinction.     

液氨储罐事故性泄漏扩散过程模拟分析

液氨是化工企业常用的原料，而每年因为液氨储罐的泄漏造成的事故也十分频繁，液氨属于高度危险性物质，一旦泄漏极可能造成灾难性后果。本文探讨了描述液氨储罐事故性泄漏及扩散过程的数学模型，并用所建模型针对某市化学园区某化工公司液氨储罐工程建设项目进行模拟分析。从模拟结果来看，采用数学模型的方法对事故后果进行预测和分析具有一定程度的可靠性，对于救灾、重大危险源编制应急事故预案以及对新建项目进行危险性预评价都具有一定程度的指导意义。     

Development of a test method against hot alkaline chemical splashes.

High temperature alkaline chemical liquids have caused injuries and hazardous situations in Finnish pulp manufacturing mills. There are no requirements and/or test method standards concerning protection against high temperature alkaline chemical splashes. This paper describes the test method development process to test and identify materials appropriate for hot liquid chemical hazard protection. In the first phase, the liquid was spilled through a stainless steel funnel and the protection performance was evaluated using a polyvinyl chloride (PVC) film under the test material. After several tentative improvements, a graphite crucible was used for heating and spilling the chemical, and a copper-coated K-type thermometer with 4 independent measuring areas was designed to measure the temperature under the material samples. The thermometer was designed to respond quickly so that peak temperatures could be measured. The main problem was to keep the spilled amount of chemical constant, which unfortunately resulted in significant variability in data.     

Experimental study and prediction of liquid nitrogen pool evaporation process on concrete surface

The vaporization rate of pool boiling process of a liquid nitrogen spilled on concrete surface was investigated by a visual experiment platform. The boiling curve for liquid nitrogen on concrete cooling process was obtained. The shapes of bubbles in three typical boiling regimes were observed. Based on the experimental results, the coefficients of the empirical formulas for nuclear boiling and film boiling are modified, and the empirical formulas for boiling of liquid nitrogen-concrete surfaces are obtained. Combined with the calculation formula of the non-steady-state semi-infinite one-dimensional heat conduction temperature, a coupled calculation model for the heat transfer and vaporization process of liquid pool on the liquid nitrogen-concrete surface is proposed. Application of this model can better predict the quality of liquid nitrogen vaporization.     

三氯化氮排放槽爆炸事故原因分析及预防处理措施

对某化工厂液氯包装工序三氯化氮排放槽爆炸事故进行了分析 ,提出了预防及处理措施     

高温热表面油液蒸发的时变性热质传递模型与实验研究

针对高温热表面油液蒸发热质传递过程的时变性,考虑这一过程中的对流传质传热,建立了热环境作用下油液蒸发的热质传递模型方程,通过无量纲变换,求得空间浓度分布和温度场随时间的变化规律。以庚烷为试验对象,对高温热表面油液蒸发过程进行了实验研究。理论分析与实验表明:庚烷蒸发过程中,刘易斯数大于1,传热速率大于传质速率;蒸发导致的质量损失与时间平方根的成正比,与液面的面积成正比,且与质量扩散系数的平方根成正比,饱和蒸气浓度越大,蒸发速率也越大。油液蒸发计算结果与试验结果基本一致,表明了模型的有效性。     

Numerical analysis of phase behavior during rapid decompression of rich natural gases

The effect of the condensation process on the gas and liquid phase behavior during rapid decompression of rich natural gases is studied in the paper numerically. A one-dimensional mathematical model of transient thermal two-phase flow of compressible multi-component natural gas mixture and liquid phase in a shock tube is developed. The set of mass, momentum and enthalpy conservation equations are solved for the gas and liquid phases. The approach to model a liquid condensation process during rapid decompression of rich natural gas mixture is proposed. The mass transfer between the gas and the liquid is taken into account by introducing the appropriate terms into the governing equations. Thermo-physical properties of multi-component natural gas mixture are calculated by solving the Equation of State (EOS) in the form of the Soave–Redlich–Kwong (SRK-EOS) model. The proposed liquid condensation model is integrated into the GDP model. A simple case of GDP model, where the liquid was not considered, was extensively validated on base and dry natural gases. The proposed two-phase model is validated against the experiments where the decompression wave speed was measured in rich natural gases at low temperature. It shows a good agreement with the experimental data.     

基于概率神经网络的液氨汽车罐车复合故障诊断

故障诊断在保证危险化学品汽车罐车运输安全方面具有重要意义。从国内交通运输安全的实际要求出发,依据液氨汽车罐车的结构特点及国家法律法规的要求,比较全面、系统地分析了液氨汽车罐车故障特征的相关参数,并将其作为概率神经网络的输入结点。根据实际可能发生的故障分类模式,考虑到故障诊断的容错能力和自适应能力,提出了基于概率神经网络的复合故障诊断模型。利用指标参数作为网络训练样本,对未知故障模式进行诊断,并以广西地区压力容器检验所液氨检测数据为例进行说明。理论分析和实例计算表明,该模型物理概念清晰,计算结果合理,精度较高,在危险化学品汽车罐车故障诊断中有很好的适用性。该项工作可为我国危险化学品汽车罐车故障智能诊断的深入开展提供参考依据。     

工艺流程中氨泄漏事故后果分类研究

氨是重要的化工原料和产品,工艺流程中氨主要以氨气、液氨、氨溶液三种状态存在。氨气、液氨、氨溶液理化特性及危险特性不同,可能造成的事故后果类型不同,分别进行三种相态下氨泄漏的事故情景分析。氨气泄漏主要考虑蒸气云爆炸、中毒,液氨泄漏主要考虑沸腾液体扩展蒸气爆炸、蒸气云爆炸、中毒,氨溶液泄漏主要考虑中毒和腐蚀。运用半球模型和高斯模型计算某尿素企业液氨球罐泄漏的危害范围。半球泄漏模型计算方法较简单,但没有考虑氨本身性质及气象条件等因素;高斯模型计算过程较复杂,其计算结果与风速、大气稳定度等条件相关。该两种方法计算结果对预防氨泄漏事故发生和氨泄漏事故预警均具有一定参考意义,如何提高模拟分析的准确度是今后研究工作的重点。     

Determining a realistic ranking of the most dangerous process equipment of the ammonia production process: A practical approach

OCI Nitrogen seeks to gain knowledge of (leading) indicators regarding the process safety performance of their ammonia production process. The current research determines the most dangerous process equipment by calculating their effects resulting from a loss of containment using DNV GL's Phast™ dispersion model. In this paper, flammable and toxic effects from a release from the main equipment of an ammonia plant have been calculated. Such an encompassing approach, which can be carried out for an entire plant, is innovative and has never been conducted before. By using this model, it has been demonstrated that the effects arising from an event of failure are the largest in process equipment containing pressurized synthesis gas and ‘warm’ liquid ammonia, meaning the ammonia buffer tanks, ammonia product pumps, and the ammonia separator. Most importantly, this document substantiates that it is possible to rank the most hazardous process equipment of the ammonia production process based on an adverse impact on humans using the calculated effect distance as a starting point for a chance of death of at least 95%. The results from the effect calculations can be used for risk mapping of an entire chemical plant or be employed and applied in a layer of protection analysis (LOPA) to establish risk mitigation measures.     

考虑气液置换的压回法气井压井过程对井底压力的影响*

为在压回法气井压井计算中进一步贴合现场实际情况,提出新的压回法气井压井过程计算方法。在压井过程中,考虑压井液与侵入井筒的气体发生置换,导致井筒流体自上而下分布为液－气液２相－气－气液２相的实际问题,建立压井过程模型,并对井底压力的变化进行计算分析。结果表明:发生气液置换对压回法压井过程井底压力以及注入压力具有明显影响,考虑气液置换对井底压力的控制可更加精确,同时,气液置换越多,压回过程所需要的注入压力越大,易引起更加严重事故。因此,气液置换过程在压回法压井过程不可忽略。     

Risk assessment of chemical process considering dynamic probability of near misses based on Bayesian theory and event tree analysis

With the development of modern automatic control systems, chemical accidents are of low frequency in most chemical plants, but once an accident happens, it often causes serious consequences. Near-misses are the precursor of accidents. As the process progresses, near misses caused by abnormal fluctuation of process variables may eventually lead to accidents. However, variables that may lead to serious consequences in the production process cannot update the risk in the life cycle of the process by traditional risk assessment methods, which do not pay enough attention to the near misses. Therefore, this paper proposed a new method based on Bayesian theory to dynamically update the probability of key variables associated with process failure risk and obtain the risk change of the near-misses. This article outlines the proposed approach and uses a chemical process of styrene production to demonstrate the application. In this chemical process, the key variables include flow rate, liquid level, pressure and temperature. In order to study the dynamic risk of the chemical process with consideration of near misses, according to the accumulated data of process variables, firstly the abnormal probability of the variables and the failure rate of safety systems associated with the variables were updated with time based on Bayesian theory. On the basis of the dynamic probability of key process variables, an event tree of possible consequences caused by variable anomalies was established. From the logical relationship of the event tree, the probability of different consequences can be obtained. The results show that the proposed risk assessment method based on Bayesian theory can overcome the shortcomings of traditional analysis methods. It shows the dynamic characteristics of the probability of different near misses, and achieves the dynamic risk analysis of chemical process accidents.     

一种新型危险化工工艺安全评估方法的设计

在安全生产过程中,建设项目风险评价在我国经过几十年的发展,无论在模型亦是方法上均有所进步,但对化工项目进行危险化工工艺风险等级评价的研究并不多见。本文按照危险化工工艺表征涉及的影响因素,在参考了日本劳动省"六阶段"的定量评价表以及危险度评价法并对15种危险化工工艺定性分析的基础上,提出了一种基于危险度评价法的更为全面的危险化工工艺辨识方法。该评价方法可用于确定危险化工工艺的风险等级。为化工企业工艺危险的实时评估和安全管理提供技术支撑和科学途径。     

基于模糊综合评价的化工工艺本质安全指数研究

建立化工工艺的本质安全评价指标体系,包括可燃性、爆炸性、毒性、反应性、温度、压力、储量等7个指标。为解决前人指数法中的边界波动效应,采用模糊综合评价建立化工工艺本质安全评价指数模型,确定各指标的权重、危险分级及对各分级的隶属函数。以甲基丙烯酸甲酯的5条工艺路线为例进行分析,结论与前人提出的指数方法的评价结果相吻合,表明该指数方法可以用来进行化工工艺的本质安全评价,以指导设计初期的本质安全型工艺路线选择。     

连续起伏管道投产过程中的气相运移研究*

为应对山区液体管道在投产过程中可能出现的气阻、超压问题,从气相运移角度出发,建立液顶气模型,研究在1个U型单元内积气形成、压缩和破碎的全过程,在此基础上,提出连接各个U型单元的气相的传递函数,探讨背压累积因素下,连续起伏管道投产过程中各个U型管段的积气情况和压力的变化,进行动态的建模和计算。以国内某原油管道的现场投产数据与模型结果进行比对。结果表明:可以更加准确地预测山区液体管道投产过程中的气相传递和压力变化过程,能为未来连续起伏大落差液体管道投产的安全稳定运行提供理论指导和技术支持。     

工厂三维建模及其事故模拟

利用Microstation软件对某化工厂区进行三维建模,在考虑实际外界风向、风速,不同点火源位置等重要影响因素的条件下,运用计算流体动力学(CFD)软件FLACS,研究了有毒、易燃易爆的氯乙烯液化气体储罐安全阀气体泄漏和储罐底部物料管线液态氯乙烯的泄漏、蒸发、扩散和爆炸作用等过程,计算结果可以给出氯乙烯火灾、爆炸或扩散中毒等事故后果的影响范围和相关精确物理量。模拟结果表明,对于常温下的氯乙烯液化气体球罐,球罐安全阀泄漏后罐区及周边不会有燃烧或爆炸危险;而物料管线在特定的液相泄漏情景下,蒸发扩散的氯乙烯气云则有可能发生气云爆炸;但在弱约束条件下,爆炸冲击波作用比较微弱。该研究方法及其结果可以为石油化工企业选址、设计布局、安全规划、风险分析、应急救援及事故调查等提供更加准确的依据。     

混合液体火灾爆炸危险性——闪点预测与实验研究

支持向量机应用核函数技术,已经成为当前国际上一个研究的热点,由于支持向量机具有良好的理论基础和泛化性能,可将其引入到混合液体闪点预测的研究之中,以期建立准确、高效的预测模型。本文建立了一个基于支持向量机的理论模型,用于预测二元互溶混合液体的闪点。根据所研究混合液体的物理性质,选择了纯物质的粘度、表面张力、配比、燃烧下限等物理参数来表征闪点,以这些参数作为输入参数,二元混合液体的闪点作为输出值,应用支持向量机方法对两者之间的内在定量关系进行模拟。结果表明,闪点预测值与实验值符合良好。本方法的提出为工程上提出了一种预测二元互溶液体闪点的有效方法,可应用于评估混合溶液的火灾爆炸危害性及本质较安全设计。     

化工园区泄漏事故安全风险评估模式研究

为减少化工事故频发造成严重人员伤亡及财产损失,在分析危化品泄漏事故类型的基础上,从事故发生概率和事故后果两方面提出危化品泄漏事故风险评估模型.以中毒事故为例,对重庆长寿化工园区内某企业一液氨储罐进行风险评估.基于概率模型计算中毒事故概率,结果表明该储罐发生泄漏引起中毒的概率较小;数值模拟结果显示:影响范围随时间的增加而...     

Quantitative evaluation of precautions on chemical tanker operations

Large quantities of liquid chemicals are carried by chemical tankers all over seas. Chemical cargoes have different properties and chemical tankers are complex ships that are designed to carry different types of chemical cargoes. Carriage of chemical cargoes contains different hazards both for human life and marine environment. There are several cargo operations that are regularly done on chemical tankers such as loading, discharging, inerting, washing tanks, sampling, and freeing gas. These operations constitute their own risks. Therefore, risk assessment has become a critical issue in maritime industry. The present investigation of this study is attempting to examine the priorities of precautions that are taken by chemical tankers before, during, and after cargo operations. Analytic hierarchy process (AHP) is used for prioritizing the precautions in order to clarify the risk assesment option that will be used for pro-active approach to prevent marine casualties. The main aim of this study is to identify an appropriate management tool to increase the level of safety for chemical tankers during cargo operations at a terminal by using the results of AHP application.