Process shutdown

Advantages of the pitot method of measurement are low pressure loss and easy installation. In some cases, installations in existing lines are made without process shutdown by hot tapping the line (7). 

Mathematically speaking, a process simulation model consists of a set of variables (stream flows, stream conditions and compositions, conditions of process equipment, etc) that can be equalities and inequalities. Simulation of steady-state processes assume that the values of all the variables are independent of time a mathematical model results in a set of algebraic equations. If, on the other hand, many of the variables were to be time dependent (m the case of simulation of batch processes, shutdowns and startups of plants, dynamic response to disturbances in a plant, etc), then the mathematical model would consist of a set of differential equations or a mixed set of differential and algebraic equations. 

As a result of these poorly designed control systems, users experience significant operational problems, including machine and process shutdowns. As with any process plant, the first objective is to achieve reliable production from the FCCU. Only with reliable production will operators start optimizing the unit. Users, therefore, are not using the... 

Minor hazard to personnel Orderly process shutdown necessary... 

Extrinsic wastes are more functional in nature and are not necessarily inherent to a specific process configuration. These may occur as a result of unit upsets, selection of auxiliary equipment, fugitive leaks, process shutdown, sample collection and handling, solvent selection, or waste handling practices. Extrinsic wastes can be, and often are, reduced readily through administrative controls, additional maintenance or improved maintenance procedures, simple recycling, minor... 

Flammable gas detection systems are typically used to initiate an alarm at a concentration level below the lower flammable limit (LFL). Two gas alarm levels (low and high) are often utilized to allow early warning prior to taking automatic actions. Detection systems may also be used to stop electrical power and initiate process shutdown. The low alarm setpoint should be —20% LFL and the high alarm level set point should be between 40%-60% LFL. Where these devices are used to initiate process shutdown or activate fire protection systems, it is common practice to use some form of voting, typically 2 out of 2, such that the frequency of spurious shutdowns or system activation is minimized. 

Once the contract personnel were safely off pad, the operator moved to a safe observation and contacted the PCC operator to order a process shutdown. The PCC operator acknowledged and replied that the shutdown signal had been sent. At approximately 1 28 p.m. an explosion occurred in the E l module and soon after, fire was noted coming from the adjacent process modules. 

A pivoted, dual-flare boom can allow the tip and ignitor pilots to be serviced without need of special services or a complete process shutdown. 

However, a plant does not always want to shut down when their SRVs need, for instance, intermediate testing because of a presumed failure. In that case, there are two options. The first solution is to install the valves on a changeover valve (Figure 10.16). In this system, one has a full redundancy of the SRV application, but this can become rather expensive. A calculation must be made weighing the initial investment against the eventual losses of a process shutdown. The investment might be justified if, otherwise, critical parts of the plant have to be shut down during each overhaul of the SRVs. 

Whereas numerous safety relief valves share many similarities, process safety interlocks are each individually tailored to the unique requirements of the process. The final parts of this chapter will discuss the critical process shutdown systems and the process safety alarms management systems used by three different major chemical plants. 

G Facility/process description (process flow, mechanical description, vessel instrumentation and controls, ESD and process shutdown philosophy, normal operating parameters, and design codes used). 

In areas where the possibility of fire is the greatest, a high speed ultraviolet detection system is employed. The ultraviolet eyes detect the presence of a flame and are interconnected with a high speed water deluge system. In some areas the fire detection devices have process shutdown capabilities. The detectors are situated such that the entire hazardous area can be monitored at all times. They are equipped with air shields that not only cool the detector but also blow clean air across the face of the lens, keeping any dust from accumulating on the lens, which assures detection capability. Further, the detectors have a built-in test lamp which serves as a check of... 

Vacuum pump in MER (Provides system vacuum for chemical processing.) Shutdown due to loss of electrical power or electrical failure Onsite or offsite electrical or mechanical malfunction Control and monitoring system indications and periodic maintenance inspections Redundant pumps Loss of all vacuum for controlling noble gas and halogen releases and for moving process fluids. 

Table 2. Input summary for the initiatiiig event of topside process shutdown. ...

The required information and the quantitative data for the initiating event of topside process shutdown initiation reviewed and added for the LOPA are summarized in Table 2. 

As explained in section 3.2, the unmitigated event fiequency for the topside process shutdown initiating event is calculated as follows ... 

---