Process components

These process components are related in series, thus if any one of the components fails, the entire system fails. The failure rates for the various components are given in Table 3. The rehabiflty and failure probabiflty are computed for each individual component using equations 1 and 2 and assuming a one-year period of operation. The results are shown in Table 4. 

Polysulfones also offer desirable properties for cookware appHcations, eg, microwave transparency and environmental resistance to most common detergents. Resistance to various sterilizing media (eg, steam, disinfectants, and gamma radiation) makes polysulfones the resin family of choice for many medical devices. Uses in the electrical and electronic industry include printed circuit boards, circuit breaker components, connectors, sockets, and business machine parts, to mention a few. The good clarity of PSF makes it attractive for food service and food processing uses. Examples of appHcations in this area include coffee decanters and automated dairy processing components. 

Determine product specifications constmct Hst of all destinations of process components (destination Hst initially consists of compositions and amounts of all desired products and by-products to be produced by the separations process). 

Fig. 3. Process components for the activated-sludge process, with aerobic digestion at plants <473.1 m /h and two-stage anaerobic digestion at plants...

A compressor is typically a specially designed device, and comes with far less surplus capacity than other process components. As a result compressors merit great care in specification of flow, inlet pressure, and discharge pressure. Similarly, the control system and equipment need to be carefully matched to provide turndown with maximum efficiency. 

A key aspect of this quality process component is to evaluate if the people doing the job have access to and are following the established procedures. There should be a system to manage the updating of procedures, communicating the changes, and training personnel on the procedures. 

Suppose X and Y are process components such that the failure of either one fails the train. The probaility of failing the train is the probability that one or the other or both fail, i.e., z = x + y with failure rates distributed as pjx), Py(y). Their combined distribution is expressed by the convolution integral (equation 2.7-1),... 

The PRA procedures guide, NUREG/ CR-23(X), partitions human reliability analysis (HRA) into four phases (Figure 4.5-1). The familiarization phase, evaluates a sequence of events to identify human actions that directly affect critical process components. From plant visits and review, this part of HRA identifies plant-specific factors that affect human performance such as good or bad procedures used in the. sequence under consideration. The familiarization phase notes items overlooked during systems evaluation. 

Furthermore, once every process component has been analyzed separately for worst case, stand-alone conditions, there is no additional safety risk created by joining the components into a system. That is, if every process component is fully protected based on its FMEA analysis, a y tern made up of several of these components will also be fully protected,... 

It is even possible that the system configuration is such that protecnon furnished by devices on one process component can protect others. That is, devices that may be required to provide adequate protection for a component standing alone may be redundant once all components are assembled in a system. This procedure is outlined below ... 

For each piece of equipment (process component), develop an FMEA by assuming in turn that each process upset that could become a potential source occurs. That is, assume a control failure, leak, or odier event leading to a process upset. 

The modified FMEA approach has been used by the API to develop RP14C. In this document ten different process components have been analyzed and a Safety Analysis Table (SAT) has been developed for each component. A sample SAT for a pressure vessel is shown in Table 14-4. The fact that Tables 14-3 and 14-4 are not identical is due to both the subjective natures of a Hazard Analysis and FMEA, and to the fact that RP14C is a consensus standard. However, although the rationale differs somewhat, the devices required are identical. (The gas make-up system in Table 14-4 is not really required by RP14C, as we shall see.)... 

The RP 14C also provides standard reasons allowing the elimination of certain devices when the process component is considered as part of an overall system. Figure 14-3 shows the Safety Analysis Checklist (SAC) for a pressure vessel. Each safety device is identified by the SAT (with the exception of gas make-up system ) is listed. It must either be installed or it can be eliminated if one of the reasons listed is valid. 

Vessel is scrubber or small trap, is not a process component, and adequate protection is provided by downstream PSL or design function (e.g., vessel is gas scrubber for pneumatic. safety system or final scrubber for flare, relief, or vent system). 

The SAT and SAC for each process component are updated periodically by API and the most recent edition should be used in any design. Plea.se note that for fired and exhaust heated components it may be necessary to include the devices required for a process tank or vessel as well as those required for the heating components. 

Listed across the top of the matrix are the various shutdown valves in the facility. A mark in each box indicates the function performed by each device to assure that it protects the process component. By comparing the functions performed by each device to the mechanical flowsheet, it is possible for an auditor to quickly ensure that the process component is indeed isolated. 

This sample is designed to summarize the key steps in the process a centralized company or division plans to follow in developing PSM. Note that the primary difterences indicated relate to reporting requirements and timeframe the process components remain the same regardless of organizational structure or management style. 

Many process components do not conform to the ideal gas laws for pressure, volume and temperature relationships. Therefore, when ideal concepts are applied by calculation, erroneous results are obtained—some not serious when the deviation from ideal is not significant, but some can be quite serious. Therefore, when data are available to confirm the ideality or non-ideality of a system, then the choice of approach is much more straightforward and can proceed with a high degree of confidence. 

Impingement or erosion-corrosion. Where exfoliated magnetite from high heat-flux areas, such as superheaters and reheaters, occurs, apart from the damage caused in turbine areas or process components, the particles may be swept into the condensate system, ultimately causing further erosion throughout the entire system... 

There are several advantages of the use of HPLC for process monitoring. First, HPLC provides both qualitative and quantitative information about a process. At the research or pilot reactor stage of development, real time monitoring increases research efficiency and provides the data for process optimization. Second, because HPLC permits continuous real-time monitoring of reactors or other process components, process upsets that might go... 

Seasonal process components are of particular interest for environmental studies and production processes. The different components of x(t) can be estimated by smoothing and filtering methods. 

After considering the direct and byproduct chemistry, the next most important thing to do is to pilot the process with all recycle loops closed. Remember the principal that the only things in chemistry that matter are temperature and concentration. By closing the recycle loops, the concentrations of process components build to equilibrium levels, and process parameters can be adjusted sooner. 

Fig. 6.3. Product aN of abundance and neutron capture cross-section for s-only nuclides in the Solar System. The main and weak s-process components are shown by the heavy and light curves respectively. Units are mb per 106 Si atoms. After Kappeler, Beer and Wisshak (1989). Copyright by IOP Publishing Ltd. Courtesy Franz Kappeler.

Accidents in chemical plants are usually the result of a complicated interaction of a number of process components. The overall process failure probability is computed from the individual component probabilities. 

Process components interact in two different fashions. In some cases a process failure requires the simultaneous failure of a number of components in parallel. This parallel structure is represented by the logical AND function. This means that the failure probabilities for the individual components must be multiplied ... 

Process components also interact in series. This means that a failure of any single component in the series of components will result in failure of the process. The logical OR function represents this case. For series components the overall process reliability is found by multiplying the reliabilities for the individual components ... 

Failure rate data for a number of typical process components are provided in Table 11-1. These are average values determined at a typical chemical process facility. Actual values would... 

Table 11-1 Failure Rate Data for Various Selected Process Components ...

A summary of computations for parallel and series process components is shown in Figure 11-3. 

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