Inside processing

The primary concern abont hazardons processes is that they be operated in a safe manner so that fires, deflagrations, detonations, and releases of flammable and toxic gases into the atmosphere or inside process bnildings are eliminated or minimized. Also of great concern from an environmental standpoint is the control and minimization of volatile organic componnd (VOC) emissions from process vents and fugitive sources. 

Inside" processes—such as modified chemical vapor deposition (MCVD) and plasma chemical vapor deposition (PCVD)—deposit doped silica on the interior surface of a fused silica tube. In MCVD, the oxidation of the halide reactants is initiated by a flame that heats the outside of the tube (Figure 4.8). In PCVD, the reaction is initiated by a microwave plasma. More than a hundred different layers with different refractive indexes (a function of glass composition) may be deposited by either process before the tube is collapsed to form a glass rod. 

FIG. 25-4 Corrosion racks used to expose corrosion samples in operating production equipment (a) inside pipes (b) inside process vessels (c) to be bolted onto baffles and brackets with process vessels. 

Determine the fire water requirements (gpm, number of sprinklers, and pump horsepower) to protect an inside process area of 200 ft2. Assume that the sprinkler nozzles have a 0.5-in orifice, the nozzle pressure is 75 psig, and the rate is 50 gpm. 

Determine the recommended ventilation rate for an inside process area (30,000 ft3) that will handle Class I liquids and gases. 

Fiber glass-reinforced plastic tanks, 24 299 Fiber grating, 11 150-151 Fiber length (FL), 18 148 Fiber manufacture, sodium bisulfite in, 23 673 Fiber-matrix bonding, 26 771-772 Fiber modification, chemical, 16 14 Fibernodes, 11 595 Fiber-optic probes, 16 524 Fiber optics, 11 128-162, 15 469 attenuation in, 11 132-133 dispersion in, 11 134-135 fiber drawing in, 11 141-145 fiber strength in, 11 141-145 history of, 11 128-131 inside processes for, 11 136-140 near-infrared, 23 141 optical amplifiers with, 11 145-146 optical fiber fabrication for,... 

Manholes inside process area battery limits should be vented at least 18 in (46 cm) above the highest pipelines or equipment within a 10-ft (3-m) radius or... 

Main pipe rack structures inside process units 1-2 hours... 

Main banks of aboveground instrument runs in cable trays (such as those coming from the control room and supported on process unit pipe racks) that are located inside process unit battery limits should be considered for fireproofing by one of the following passive methods ... 

In Effects of Motion on Design of Process Facilities for Floating Systems" Rice provides a theoretical analysis coupled with motion-simulation work in an effort to understand fluid motion inside process equipment on floating vessels. This work has led to the establishment of process-equipment sizing criteria for all types of vessel motion transmitted from the marine vessel. Design of internal baffling and other internals to dampen and control the fluid motion is reviewed. 

Compute the process-side heat-transfer coefficient. The correlations for inside (process-side) heat-transfer coefficient in an agitated tank are similar to those for heat transfer in pipe flow, except that the impeller Reynolds number and geometric factors associated with the tank and impeller are used and the coefficients and exponents are different. A typical correlation for the agitated heat-transfer Nusselt number (ANu = htT/k) of a jacketed tank is expressed as... 

It has been found that glycerine left inside processing vessels, especially carbon columns, can degrade and develop hard-to-remove odors. Therefore, process equipment should be cleaned completely after shutdown, and carbon columns blown down with air and washed with water. Also, fresh carbon can sometimes contain odor-causing impurities. The carbon can be washed with distilled glycerine that can be subsequently redistilled or sold as a lower grade. 

Design history inside process-integrated tools is automatically recorded and organized in trace chunks using a concrete traceability model. Finally, the captured trace chunks are stored in a trace repository. 

A traceability model extends a NATURE process model in order to enable the almost automatic capture of extended traceability information concerning the design history inside process-integrated tools. It is able to represent the process steps executed, the products involved, the major decisions taken, and their possible interrelations. 

The transition as described above relies on a representation of process templates using the partial model Process Models of CLiP. Substituting Process Models with its recently developed successor, the Process Ontology described in Subsect. 2.4.6, is straightforward. Similarly, the other partial models of CLiP can be replaced with OntoCAPE (cf. Subsect. 2.2.4). In contrast, the integration of the Decision Ontology (see Subsect. 2.5), which replaces the simple IBIS-based rationale model inside Process Models with a more expressive variant of DRL, is still an open issue. 

Vapor cloud explosions are due to rapid combustion of flammable gas, mist, or small particles that generate pressure effects due to confinement they can occur inside process equipment or pipes, buildings, and other contained areas. A vapor cloud explosion can be either a deflagration or a detonation (the distinction between deflagrations and detonations is important when deciding on whether or not to use a flame arrestor in pressure relief systems). 

Inside processes such as modified chemical vapor deposition (MCVD) had a different origin. Chemical vapor deposition (CVD) had long been used In the electronics industry for fabrication of silicon devices and was adapted to produce silica layers inside substrate tubes [18j. In CVD, the concentration of reactants is very low to inhibit gas phase reaction in favor of a heterogeneous wall reaction which produced a vitreous, particle-free deposit on the substrate. This is fine for the 1000 A films required for semiconductor processing, but fails to produce thick deposits required for fiber. CVD was therefore reversed, the reactant concentration was increased and large volumes of particles were produced inside the silica substrate tube. They deposited on the tube wall and were sintered to glass. 

A second inside process, plasma chemical vapor deposition (PCVD) [26], is similar to MCVD. It uses the same reactants inside a silica tube, which is collapsed after deposition and drawn to fiber, but reaction inside the tube is initiated by a non-isothermal microwave plasma traversing down the tube, rather than by heating the exterior of the tube, as shown in Figure 16. 

It is common that decisions for implementing beneficial improvement ideas are made with the evaluation based on the inside process battery limit (ISBL). It is not surprising to find, in some eases, that the implemented energy-saving projects deliver far less benefits and require mueh high capital compared to what are predicted from evaluation. The reason is that energy savings at the process level can only be realized at the site-wide balanees when the utility bills come at the end of the year. 

A Loss of Containment or LoC of process equipment follows when all barriers fail. The uncontrolled deviations from normal or abnormal process conditions and operations that are so extreme that leaks, cracks, ruptures or failing barriers cause the uncontrolled transport of materials from inside process equipment to the outside. In the current version of Platypus, the LoC s are of arbitrary size. That is to say that Platypus does not predict the size of the leak. The reason for that is the size of the leak is a consequence rather than a cause, which puts it in the right-hand side of the bow-tie. 

The inside process is somethnes called inside vapor phase oxidation (IVPO) or inside vapor deposition (IVD). However, it is perhaps most commonly referred to as modified chemical vapor deposition (MCVD). In one variation, perhaps not currently in commercial use, an argon/oxygen plasma is generated within the tube by microwave radiation to provide the thermal energy for the chemical reaction, instead of relying on heat from a burner outside the tube. 

Another technique proposed for the inside process is plasma chemical vapor deposition (PCVD). In this version of the process, a low-pressure plasma is generated inside the tube that does not lead to soot generation, but rather allows a heterogeneously nucleated chemical reaction to occur at the inner surface of the tube, so that the glass is built up in molecular-scale layers. This is a true chemical vapor deposition (CVD) process. More layers are required than with soot, but the process can be controlled more precisely. Unfortunately, the process has not yet proved commercially economical. 

High-fluid velocity will tend to erode off the protective corrosion layer inside process piping. This exposes new, clean, and reactive metal to the corrosive oxygen and water. What is meant by erosive velocity For aqueous systems with a few hundred parts per million (ppm) of particulates, an erosive velocity is... 

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