Using the ASTM CHETAH program in chemical process hazard evaluation

The CHETAH program has proven to be of great utility in the assessment of reactive chemicals hazards associated with the development of new chemicals and chemical processes. At the Dow Chemical Company, the most frequent use of the program is for the estimation of heats of reaction. Reaction heats are often the single most important parameter in reactive chemicals evaluation since most “worst case” scenarios involve the instantaneous liberation of the reaction energy. Another common use of the program is using CHETAH's unique capability to predict the “explosive” behavior of a material or mixture solely from a knowledge of its molecular structure. Several examples of day-to-day use of the program are presented. Current development activity in the ASTM subcommittee which supports CHETAH are discussed. These include new hazard evaluation criteria, better thermodynamic property estimation techniques, and user friendly versions of the program.     

The advantages and limitations of adiabatic Dewar calorimetry in chemical hazard testing

Adiabatic Dewar Calorimeters can be used to measure the temperature time curve of self heating and the induction time of thermal explosions. The important experimental parameters which allow the data to be determined under conditions which directly simulate plant situations are described. The advantages and limitations of the technique are discussed, showing where it can be used to define the process conditions under which uncontrolled reaction could be initiated and to quantify the consequences of such reactions.     

Management of quantitative risk assessment in the chemical process industry

Growing concern about the risk of major chemical accidents in the U.S. has led both government and industry to find new ways to identify and evaluate potential hazards. Among the most promising (and misunderstood) approaches is a collection of techniques called quantitative risk assessment (QRA). Adapted primarily from probabilistic risk assessment approaches developed in other industries, the use of QRA is spreading rapidly through the U.S. chemical industry. Of equal importance, legislators and regulatory agencies at the state and federal level are making QRA an integral part of their proposals for mandatory accident prevention measures. This paper summarizes a workshop on QRA that was presented at the International Conference and Workshop on Process Safety Management, sponsored by the AIChE Center for Chemical Process Safety, in Toronto during May 1990. It is based on A Manager's Guide to QRA [1] developed for the Chemical Manufacturers Association. This paper gives an overview of the Guide and discusses important implications concerning the increasing acceptance of QRA as a chemical regulatory tool.     

Moral hazard in repeated procurement of services

This paper analyzes repeated procurement of services as a two period model with a potential repeated agency relationship. In the first period, there is an incumbent who provides a service. In the second period, there is a contest stage in which the principal selects the next service provider. The agents’ effort is non-contractible and the contest stage is the mechanism to mitigate potential moral hazard problems. The principal takes account of the past service effort in the contest stage by choosing the weight of past effort and the degree of substitutability between past and current efforts. The results show that, when the principal does not value contest effort, considering past effort as the relevant effort in the contest is optimal. When the principal values contest effort and effort cost increases, decreasing substitutability between efforts is optimal.     

Documentation of hazard and operability studies

The recently enacted Clean Air Act Amendments of 1990 [1] and the proposed OSHA Process Safety Management Standard [2] both require that hazard evaluations be completed on all facilities that handle hazardous chemicals. Reports of the hazard evaluations must be kept on file and will be subject to inspection during an OSHA compliance audit. This paper outlines those concepts that are important in the preparation of the documentation of a Hazards and Operability (HAZOP) study.     

R&D and marketing productivities from cross-sectional data: A study of German chemical corporations

Abstract
The adoption of EC-regulations in German law on annual corporate reporting has introduced two new formats for profit and loss statements. Using this newly available data from a sample of German chemical companies, production functions are estimated with sales as an output measure, and R&D and marketing as input measures. It is shown that these factors are peripheral rather than complete substitutes. Marginal productivities of the factors imply the opportunity for relative increases of R&D expenditure over marketing expenditure.     

Documentation and utilization of the results of hazard evaluation studies

A Hazard Evaluation (HE) study is not finished until the study documentation is complete and all of the issues and recommendations from the HE study have been resolved. While the extent and detail of the HE documentation will vary depending on the HE technique used, and on the stage in the process life cycle at which the study is performed, all studies should include documentation in three categories:

• 1 Process documentation, defining the design and intended operation of the facility at the time the HE study was performed.
• 2 HE study documentation, recording the actual performance of the HE study and including, for example, meeting notes or worksheets, logic models, hazard index calculations, etc.
• 3 Action documentation, summarizing all recommendations, perhaps with prioritization, and listing actions taken in response to the recommendations.

Thorough and complete documentation of HE studies is essential for understanding the concerns which give rise to each recommendation, tracking action taken on recommendations to insure that all are resolved, using the HE study as a basis for subsequent HE or quantitative risk analysis studies, using the HE study to assist in the management of change, and periodic updating of the HE study. Modern computer based information storage and retrieval technology also opens the potential for use of HE study documentation as a tool for training and for process troubleshooting.     

Increased fire hazard of N-heterocyclic compounds substituted by S-containing group

Release of CS₂ and/or H₂S caused by friction is demonstrated on two N-heterocyclic compounds carrying S-atom containing substituents. Because of the generation of electrostatic charge and creeping discharge, simultaneously brought about by friction, ignition and possible explosion of the released gaseous products of decomposition could occur. The tested compounds proved not to be sensitive to impact. Nonetheless, fire and explosion hazard of dusts must not be judged by their sensitivity to impact only. It is necessary to test their sensitivity to friction as well.     

投资前风险的识别与防范

1　引言随着我国企业改革的逐步深入 ,我国的市场投资结构已经发生了很大的变化。原计划经济下主要由政府进行投资决策的模式正逐渐消失 ,取而代之的是多元化、分散化的投资格局和谁投资、谁收益、谁承担风险的投资理念。企业日益成为市场的投资主体 ,投资也日益成为企业发展的     

电力市场中无功电压运行考核方法

分析了无功电力在电网,电厂与用户之间的关系是相互依存和相互支持的,它不同于有功电力市场中的供求、买卖关系。因此,在电力市场中无功电力不能竞价上网,在无功电力交换中不能以能量法则确定无功电能的电价。根据上述客观规律和我国无功电压管理的现状,按电力系统安全、稳定运行与市场化运行的相互协调原则,探讨了在有功电力市场中无功电压的考核办法、必要性和操作规则。     

Demand-side reactive strategies for supply disruptions in a multiple-product system

This research examines demand-side reactive strategies for supply disruption in a multiple assemble-to-order system. We consider an assemble-to-order system with two substitute products where the demand is price-sensitive and disruption-sensitive. Two different supply disruption situations are examined: disruption of the low-value component and disruption of the high-value component. We propose and compare the performance of four reactive strategies for managing supply disruptions, namely, the backordering strategy, the upgrading/downgrading strategy, the compensation strategy, and the mixed strategy. We find that the compensation strategy and the mixed strategy can keep more customers than the backordering strategy and the upgrading strategy during the supply disruption of the low-value product. For the disruption of the high-value product, the total number of customers keeps constant. But it does lead to the reallocation of customers among the products. We find that the mixed strategy is the best reactive strategy and the backordering strategy is the worst one among the four reactive strategies.     

2001年世界化工电子商务回顾

尽管化工电子商务网站的数量在２００１年没有增加很多，但现有网站及化工行业电子商务实践者的各项新举措，却显示出化工行业的人们开始冷静而务实地探讨电子商务的真正价值。越来越多的化工企业开始相信网上交易的优势，化工产品的网上交易量持续攀升，其热销局面与今年全球化工市场的低迷状态形成了鲜明的反差。前不久，世界著名的化工电子商务网站ChemConnect宣布其网上交易量连续第七个季度创下纪录，其２００１年二季度网上贸易量比一季度增长了３０％，网站有望在２００２年底或２００３年初进入盈利期。而CheMatch的网上交易量则…     

Portfolio assessment in practice in engineering

Summary A portfolio assessment scheme, introduced for one course in 1990 in the School of Engineering, Sheffield Hallam University is proving to be both a stimulus and support for change. The scheme is described and its impact discussed in terms of staff development, the student experience and curriculum development.