Plant hazard selection techniques hazards

Hazard analysis (HAZAN) is a quantitative way of assessing the likelihood of failure. Other names associated with this technique are risk analysis, quantitative risk assessment (QRA), and probability risk assessment (PRA). Keltz [44] expressed the view that HAZAN is a selective technique while HAZOP can be readily applied to new design and major modification. Some limitations of HAZOP are its inability to detect every weakness in design such as in plant layout, or miss hazards due to leaks on lines that pass through or close to a unit but cany material that is not used on that unit. In any case, hazards should... 

In the previous chapter, it was established that in industry, plant hazards can cause harm to property (plant—machinery, asset), people, or the environment. So, it is important to develop some means of analyzing these and come up with a solution. Unfortunately, it is not as straightforward as it sounds. There are plenty of plant hazard analysis (PHA) techniques and each of them has certain strengths and weaknesses. Also each specific plant and associated hazard has specific requirements to be matched so that hazard analysis will be effective. In this chapter, various hazards (in generic terms) will be examined to judge their importance, conditions, quality, etc. so that out of so many techniques available for PHA it is possible to select which one is better (not the best because that needs to be done by experts specifically for the concerned plant) suited for the type of plant. So, discussion will be more toward evaluation of PHA techniques. Some PHA is more suited for process safety management (PSM) and is sometimes more applicable for internal fault effects [e.g., hazard and operability study (HAZOP)]. In contrast, hazard identification (HAZID) is applicable for other plants, especially for the identification of external effects and maj or incidents. HAZID is also covered in this chapter. As a continuation of the same discussion, it will be better to look at various aspects of risk analysis with preliminary ideas already developed in the previous chapter. In risk analysis risk assessment, control measures for safety management systems (SMSs) will be discussed to complete the topic. 

The safety regulations and procedures will be automated and embedded within the plant model that to be realized in the plant enterprise systems to ensure full compliance with plant safety regulations. Hazard evaluation techniques are automated and integrated with decision support to select and apply the most suitable hazard evaluation technique. The results of the hazard evaluation technique will be monitored and followed-up using an intelligent module. Accident database will be constructed to... 

Figure 9-14 shows an example of the interaction between HEM within CAPE-SAFE and the design environment CAPE-CAD within the plant enterprise engineering environment. The sequence of activities that will be carried out by HEM are shown where the HDE will decide the suitable hazard evaluation technique based on the selection criteria and process design type. In this figure, the outline structure of the database is proposed. For example, the hazard evaluation results will include the cause, consequence of such hazard, the connected equipment, quantitative results i.e. severity / risk, qualitative results i.e. low / medium / high, and corrective action such as use of alarm / relief valve. 

The burning of coal in thermal power plants results in major pollutants such as suspended particulate matter (SPM), sulphur dioxide (SO2), oxides of nitrogen (NOx) etc, of vdiich NOx is believed to be a key con nent responsible for several hazards associated with ecology and human health(l). Given the relative abundance of coal in India, coal-based thermal power plants will continue to play a dominant role in the power sector. Therefore NOx abatement through primary and secondary measures assumes great importance. Post combustion techniques such as selective catalytic reduction (SCR) can reduce NOx emissions by >95% (2). 

It is clearly not safe to test unknown reactions or compounds in a full-size reactor, as a vigorous exotherm may overcome the protection systems provided. Various theoretical techniques and small-scale tests have therefore been devised to provide data on the likelihood and severity of a runaway reaction. They vary from simple calculations and basic heating tests to sophisticated simulations of full-size plant. This chapter describes the main theoretical techniques and experimental tests available for identifying chemical reaction hazards, and suggests how to select a suitable test regime. 

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