Batch processes hazard study

Generally, although not exclusively, a scrubber with a recycle loop of the caustic scrubbing liquor is used cases of once-through scrubbing liquor operation do exist. The scrubber may be operated in batch, semi-batch or continuous mode with respect to the liquid. Process hazards exist in batch and continuous mode, the most significant of which is over-chlorination. Batch-wise operations leads to periodic high loads on the hypochlorite destruction unit. In order to even out these loads, and improve the process safety, a study of alternative treatment options has been undertaken. 

The easiest way to approach such processes is for members of the study team to make themselves very familiar with the steps in the batch process so that it is clear that (for example) no flow might be the normal condition at step 1, but at step 5 it generates a series of hazardous causes and consequences. 

As defined in the CCPS Book "Guidelines for Hazard Evaluation Procedures (CCPS, 2008), the nodes can be the operating steps in a batch process analyzed by a HAZOP study. Following this approach, the nodes were based on the coke drums steps hsted on Table 1. Therefore, for each step of the coke drum cycle, a node was defined considering the drum and aU the ahgmnents needed to perform that phase. Preferably, the nodes boimdaries included the valves that should be opened to allow the operating step to occur. 

The batch process reactor system adds more flexibility but is probably the biggest contributor to waste generation. A detailed breakdown of the unit operations will give clear indications to the areas of manipulation which give most impact on waste minimisation. A step by step breakdown, as used in a Hazard and Operability (HAZOP) study, is applicable to optimising batch processes with respect to waste minimisation. 

Performance assessment and alarm management with scope for improvements Performance matrices and questionnaires Separate section for alerts Alarm suppression hazard study Risk assessment and priority determination Separate section for batch process... 

When failure occurs, the simplest action is to stop or hold at the current operating state in response to any abnormal condition, and let the process operator determine the cause of the problem. However, some failures lead to hazardous conditions that require immediate action waiting for the operator to decide what to do is not acceptable. The appropriate response to such situations is best determined in conjunction with process hazards and operability (HAZOP) studies. For example, guidelines for safe operation of batch reaction systems have been published (Center for Chemical Process Safety, 1999). 

Radiation exposure is one of the most well-studied hazards to human health, but it has not been possible to link any increased incidence of impaired health at the levels of exposure that are allowed for laboratory personnel. However, higher radiation exposure is harmful, which has several important implications. First, key prerequisites are that personnel involved in the handling of radioactive material are properly educated in how to avoid unnecessary exposure to people and the environment, that appropriate protective and dosimetry devices are used and that a plan is implemented for the handling and disposal of material. Second, it is usually not possible to use normal laboratory or pilot plant-scale equipment, since such batch sizes will require the handling of excessive amounts of radioactivity. Therefore, micro-scale equipment may be developed for certain processes. 

Inherent hazards In process industries, various hazards such as toxicity, flammability, fire, explosion, etc. can be analyzed by any of the analysis processes, but if a hazard involves failure of equipment, or more than one failure, then a more detailed study may he involved and a simple system may not be suitable. In batch or manufacturing plants a similar logic applies. So, the team leader needs to adopt a different approach to address inherent hazards. 

This information sharing scheme has been tested using several industrial case studies. It was found that approximately 90% to 95% of the process information required by PHASuite can be gathered from Batch Plus . The remaining information is mainly the information that has not been specified in Batch Plus such as the material hazardous properties. Sharing information has greatly reduced the time and error associated with reentering the information. In addition, it makes the cooperation between these different tools possible. 

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