Equipment interactions

For the purpose of this chapter, instrumentation will be considered everything from the primary element monitoring the controlled variable through the control valve performing the throttling action. The process equipment interacts with the instrumentation to provide the process... 

This safety audit is used for identifying inputs and material flows, processes and intermediates, and final products - but with special attention paid to human-material/process/equipment interactions that could result in (a) sudden and accidental releases/spills, (b) mechanical failure-based injuries, and (c) physical injuries - cuts, abrasions, and so on, as well as ergonomic hazards. Additional sources of adverse effects/safety problem areas are records/ knowledge of in-plant accidents/near misses, equipment failures, customer complaints, inadequate secondary prevention/safety procedures and equipment (including components that can be rendered non-operable upon unanticipated events), and inadequacies in suppliers of material and equipment or maintenance services. 

In most plant design situations of practical interest, however, the several pieces of equipment interact with each other, the output of one unit being the input to another that in turn may recycle part of its output to the inputter. Common examples are an absorber-stripper combination in which the performance of the absorber depends on the quality of the absorbent being returned from the stripper, or a catalytic cracker-catalyst regenerator system whose two parts interact closely. 

Ithough this book is devoted to the seiection and design of individuai equipment, some mention shouid be made of integration of a number of units m I into a prooess. Eaoh pieoe of equipment interacts... 

II. Exploiting Equipment Interactions The designer needs to consider total system interactions before finalizing scope for any equipment. Consider a revamp project with the main objective of increasing the duty of a column s feed pre-heater it will require assessment of the condenser s maximum capacity and top rectifying tray section. Simulation of the whole process is needed to understand system interactions. Lee et al. (2007) and Zhu (2014) described ethylene plant retrofit cases to emphasize the importance of system interactions in revamps. 

Minimize equipment/fixture size to limit forward bending or reaching, as much as possible to allow for tote pans and/or parts trays to be positioned in front of the operator. AU operator/equipment interaction issues must be considered. 

Validation demonstrates that the installed SIS operates according to the design basis and that appropriate documentation is in place to support its long-term management. An input-to-output test is used to prove that the SIS functions properly and that the SIS equipment interacts as intended with other systems, such as the BPCS and operator interface. The Site Acceptance Test (SAT) also provides an opportunity for a first-pass validation of the operating and maintenance procedures. Validation must be completed prior to the initiation of any operating mode where a hazardous event could occur that would require the operation of a new or modified SIS. Some users require that validation be repeated after any major process outage or shutdown. 

In the case of sequential controls, startup, running, and shutdown modules are checked for operator action. All critical timings (including waiting time and monitoring time) and major equipment interactions, etc. are monitored. For each sequential step module, similar considerations are applicable also. In addition to this the overall sequence activation/deactivation sequence and communications are also considered during the study. 

Any automated interface between a human and automated process can be evaluated, such as pilot/cockpit controls, or controller/ display, maintainer/equipment interactions. 

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