Case studies chemical plant

Let us take the case of chemical plant hazards and see how they are related to the hazard study methods. These give us an idea of how a combination of conditions must be tested to reveal conditions that could cause an accident. 

H. F. Rase, Chemical Reactor Design for Process Plants, Vol. 2 Case Studies, John Wiley Sons, 1977. 

Rase Case Studies and Design Data, vol. 2 of Chemical Reactor Design for Process Plants, Wiley 1977) has these items ... 

A case study of the hydrogenation of cottonseed oil is made by Rase [Chemical Reactor De.sign for Proce.s.s Plants, vol. 2, Wiley, 1977, pp. 161-178). 

Papazoglou, I. A. et al., 1992, On the Management of Severe Chemical Accidents DECARA A Computer code for Consequence Analysis in Chemical Installations Case Study September 14, 1998 Ammonia Plant, J. Haz. Mat. 31, pp 135-153. 

Generally speaking, typical major incident conditions correspond to a release of some ten thousands of kilograms of some hydrocarbon at the site of a chemical plant or refinery that is characterized by the presence of obstructed and partially confined areas in the form of densely spaced equipment. The relative agreement with results derived from the multienergy method indicates that application of this concept is a reasonable approach for this case study. 

The present work will apply one of the above mentioned 3D codes, namely the EXSIM code, to a case study of gas explosions in a process plant. The scenario was specified by Mancini for use in a workshop at a recent conference arranged by the Center for Chemical Process Safety of the American Institute of Chemical Engineers (CCPS/AIChE 1991). 

The intention of this section is to provide a selection of case studies of varying complexity and from different stages of chemical process plant operation. The purpose of these case studies is to indicate that human error occurs at all stages of plant operation, and to emphasize the need to get at root causes. The case studies are grouped under a number of headings to illustrate some of the commonly recurring causal factors. Many of these factors will be discussed in later chapters. 

The first set of case studies illustrates errors due to the inadequate design of the human-machine interface (HMI). The HMI is the boundary across which information is transmitted between the process and the plant worker. In the context of process control, the HMI may consist of analog displays such as chart records and dials, or modem video display unit (VDU) based control systems. Besides display elements, the HMI also includes controls such as buttons and switches, or devices such as trackballs in the case of computer controlled systems. The concept of the HMI can also be extended to include all means of conveying information to the worker, including the labeling of control equipment components and chemical containers. Further discussion regarding the HMI is provided in Chapter 2. This section contains examples of deficiencies in the display of process information, in various forms of labeling, and the use of inappropriate instrumentation scales. 

Case study 3 illustrates the use of proactive techniques to analyze operator tasks, predict errors and develop methods to prevent an error occurring. Methods for the development of operating instructions and checklists are shown using the same chemical plant as in case study 2. 

The case study described here concerns a human factors audit of a computer controlled process system which was being introduced in a distillation imit of a chemical plant. The unit was in transition from replacing its pneumatic panel instrumentation with the new system. However, control had not yet been transferred and the staff were still using the panel instrumentation. The role of the project was to evaluate a preliminary design of the computer-based display system and provide recommendations for future development. 

Tlie following simplified example, constructed by Hendershot, will facilitate tlie transition to tlie case studies. Suppose tliat a risk assessment is being conducted at a chemical plant to detenuine the consequences of two incidents (tlie initiating events of die event tree shown in Fig. 21.1.1) defined as... 

Figure 11.3 is the representation of the case study that is used to demonstrate the performance of the proposed model it is taken from directly from Chapter 10. To facilitate understanding, this case study is described in some detail in this chapter. The plant, which constitutes 30% of production and consumes 55% of utility steam in the multinational agrochemical facility of choice, involves the manufacture of an herbicide. The saturated steam is produced from a coal fired boiler at 10 bar absolute pressure and 3 t/h, although it is only used at 4 bar in the chosen process. The process entails 3 consecutive chemical reactions which take place in 4 reactors. The first reaction, which uses water as a solvent, takes place in reactors R1 and R2. 

The methods described above were tested at two sites in Hawaii The Nuuanu reservoir on Oahu, which is above downtown Honolulu, and the Waikoloa Dam on Hawaii Island, which is above the town of Waimea. In both cases the analyses were performed with and without topographic data obtained by a field survey crew. Detailed results from the ca e studies and results of a sensitivity analysis are reported elsewhere. The flood inundation maps produced for Waimea and Honolulu were overlaid onto several GIS infrastructure layers. These layers included major roads, secondary roads, schools, nursing homes, hospitals, police stations, fire stations, civil defense headquarters, chemical plants, electric plants and transmission lines, water plants, and wells (which could be contaminated by floodwaters). Critical facilities in the flood zone were identified and listed along with their mailing addresses and phone numbers of contact personnel. 

BCME is also found as an impurity (1-7%) in the related CMME. Fourteen cases of lung cancer, mainly of oat cell type, were reported in a chemical plant where exposure to CMME occurred. In the reported epidemiological studies, insufficient evidence is available to separate the carcinogenic effects of the two compounds. ... 

Allelopathic interactions are complex. Tm aware of no case where one chemical has been unequivocally proven to explain the entire situation. Almost all allelopathic interactions involve not only products of higher plants but also those of microbes, either as enhancers or detoxifiers. All cases require chemical characterization work followed by intensive studies by plant physiologists. Seldom can all the work be accomplished within one group. Simply, this means we must work together. 

In one epidemiological study of 138 workers exposed to vinylidene chloride in the United States, no excess of cancer was found, but follow-up was incomplete, and nearly 40% of the workers had less than 15 years latency since first exposure (lARC, 1986). In a study in the Federal Republic of Germany of 629 workers exposed to vinylidene chloride, seven deaths from cancer (five bronchial carcinomas) were reported this number was not in excess of the expected value. Two cases of bronchial carcinoma were foimd in workers, both of whom were 37 years old, whereas 0.07 were expected for persons aged 35-39 years (Thiess et al., 1979). The limitations of these two studies preclude assessment of the carcinogenicity of the agent to humans. No specific association was found between exposure to vinylidene chloride and an excess of lung cancer observed in a synthetic chemicals plant in the United States. 

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