Continuous processes hazard study

A three-step nitration process of toluene is described. The advantages of the modified process are reduced waste, less hazardous operation, reduced oleum requirement, partial replacement of coned HN03 with dil HN03, and higher rate of toluene flow into the reactor (Ref 86) The continuous process of H.C. Prime (Ref 73) for preparing TNT was studied by thin-layer chromatography on silica gel with a starch binder and a fluorescent indicator. The nitration... 

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. 

In the second report, the Royal Society Study Group called an environmental hazard. an event, or continuing process, which, if realized, will lead to circumstances having the potential to degrade, directly or indirectly, the quality of the environment in the short or longer term . 

The hazard 1 study may have decided that functional safety items such as hazards arising fi om operation of the process or its equipment should be managed in accordance with the principles laid down in lEC 61508. In such cases the hazard study team will be directed to provide inputs to the Safety Life-Cycle (SLC) Phase 2 and Phase 3 studies and to provide continuing support for the SLC studies. 

Our first task is to make sure we have some continuity from the previous material on hazard studies since it is the transition from hazard study to safety requirements specification that is so critical to the quality of the SIS solutions. We shall look at the development phases where the overall safety requirements are defined and then risk reduction tasks are allocated to SIS and non-SIS contributors. The development process leads to the actual SRS for the safety system that is to be designed and installed. 

When considering release scenarios, the most hazardous unit in a plant should be chosen, based on inventoiy and process conditions. The idea is to imagine the release of material in the fastest way that is reasonably possible. The worst realistic scenario should be considered. This can be based on the outcome of a review, from a HAZOP study or a hazard analysis. The time a scenario will take is almost always considered to be continuous, because after a few minutes a stable dispersion distance exists. Making the time longer will not necessarily change the hazard distance. 

Hazard and Operability (HAZOP) Study Scenario- based Inductive/ deductive By deviation from intended operation Processing systems with parameters such as flow, pressure, and temperature Good for both procedure-based and continuous operations Can analyze complex processes with multiple safeguards Only looks at causes that could lead to identified deviations Higher... 

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