Operational Features

Several operational features of membrane reactors were listed in an earlier section. We consider a few important ones here. 

A particularly useful feature of a membrane is that it integrates reaction and separation into a single process, thereby increasing the conversion beyond equilibrium. If this concept can be extended to an integration of two reactions. 

One can set up equations based on this model for transport of mass, as well as energy, axially through the reactor which also includes transport across the membrane. But we restrict our treatment here to a few important qualitative observations (see Itoh and Govind, 1989a, for a quantitative model) when the reactor is operated adiabatically. 

Controlled Addition of One of the Reactants in a Bimolecular Reaction Using an IMR-P 

A reference to this method of operation was made earlier. There are several instances of industrial organic reactions that are bimolecular and exothermic. An important example is the production of chloromethanes. The temperature rise can be controlled by axially distributed addition of chlorine at several discrete points into a packed-bed, fluidized-bed, or empty tube reactor through which methane is passed (Doraiswamy et al., 1975). The membrane is an ideal choice for such reactions because now it can be allowed to permeate over the entire length of the membrane from the shell side into the inner tube or vice versa. 

The ejector-based reactor can be constructed in various configurations. Firstly, the jet can be either upflow or downflow, hi this book, only the downflow type is considered. In this type, the venturi loop reactor can be with or without a draft mbe. In case there is a draft tube, there is an additional internal circulation loop within the reactor. An outer circulation loop already exists because the hquid + catalyst slurry is continuously recycled by the external pump through the heat exchanger and the primary nozzle. 

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Horner, M.W., GE Aeroderivative Gas Turbines—Design and Operating Features, 39th GE Turbine State-of-the-Art Technology, Seminar, August 1996. 

Several manufacturers make explosimeters or combustible gas indicators. Although they differ somewhat in design and operating features, their operation is based on the fact that a measurable amount of heat is released when a combustible gas or vapor is burned. Most meters contain a battery-operated electrical circuit known as a Wheatstone bridge, which is balanced by means of controls on the outside of the instrument. 

Two studies resolved the Unresolved Safety Issue A-44, "Station Blackout." The first siudy, The Reliability of Emergency AC Power Systems in Nuclear Power Plants," when combined uh die lelevant loss-oToffsite-power frequency, provides estimates of station-blackout frequencies lor 18 nuclear power plants and 10 generic designs. The study also identified the design and operational features most important to the reliability of AC power systems. The second study, "Station Blackout Accident Analysis" (NUREG/CR-3226), focused on the relative importance to risk of laiion blackout events and the plant design and operational features that would reduce this risk. 

CANDU-9 is the next generation of CANDUs. It is a larger version of the CANDU producing 870 MWe, the CANDU-9 to complement the mid-size CANDU-6 with updated proven technology, a modified CANDU-6 station layout, improved construction methods and operational features. Standardization, a feature of CANDU reactors, is emphasized in CANDU-9 in the key components (steam generators, coolant pumps, pressure tubes, etc.) being the same design as those proven in service at CANDU power stations. 

The thermal behavior of a zone is affected by the presence of internal heat sources and by HVAC operating features, which are dealt in the next sections. 

Figure 8-125 [192] presem.s a typical performance diagram of the operating features of a sieve tra. ... 

The manufacturer of structures that satisfy API Standard 4F must also furnish the purchaser with one set of instructions that covers operational features, block reeving diagram, and lubrication points for each drilling or well servicing structure. Instructions should include the raising and lowering of the mast and a facsimile of the API nameplate. 

Because systems are normally not designed for use with this type of fluid, certain aspects should be reviewed with the equipment and fluid suppliers before a decision to use such fluids can be taken. These are compatibility with filters, seals, gaskets, hoses, paints and any non-ferrous metals used in the equipment. Condensation corrosion effect on ferrous metals, fluid-mixing equipment needed, control of microbial infection together with overall maintaining and control of fluid dilution and the disposal of waste fluid must also be considered. Provided such attention is paid to these designs and operating features, the cost reductions have proved very beneficial to the overall plant cost effectiveness. 

Coatings should only be applied to fully and correctly prepared surfaces. Surface preparation is discussed elsewhere in this text however, the following undesirable surface design/operational features should be eliminated wherever possible ... 

The extraction, though, of the so-called pivotal features from operating data, encounters the same impediments that we discussed earlier on the subject of process trends representation (1) localization in time of operating features and (2) the multiscale content of operating trends. It is clear, therefore, that any systematic and sound methodology for the identification of patterns between process data and operating conditions can be built only on formal and sound descriptions of process trends. 

From the 1960s onward, alkaline zinc-manganese dioxide batteries started to be produced. They have appreciably better electrical performance parameters (see Section 19.4.3) but do not differ from Leclanche batteries in their operating features, are produced in identical sizes, and can be used interchangeably with them. Thus, a gradual changeover occurred and phaseout of the older system is now almost complete. 

A variety of centrifugal filter and sedimenter designs is used. The main types are listed in Table 10.5. They can be classified by a number of design and operating features, such as ... 

Drying equipment can be classified according to the following design and operating features ... 

For the checklist portion of the analysis, the PrHA team leader obtains or develops an appropriate checklist for the team to use. This list need not be as detailed as those used for a standard checklist analysis. Rather than focusing on a specific list of design or operating features, the checklist used here should focus on general hazardous characteristics of the process. 

For example, a traditional checklist is, by definition, based on the process experience the author accumulates from various sources. The checklist is likely to provide incomplete insights into the design, procedural, and operating features necessary for a safe process. The what-if part of the analysis uses a team s creativity and experience to brainstorm potential accident scenarios. However, because the what-if analysis method is usually not as detailed, systematic, or thorough as some of the more regimented approaches (e.g., HAZOP study, FMEA), use of a checklist permits the PrHA team to fill in any gaps in their thought process. 

To provide effective process safety features they should be effective operational features. Providing safeguards that are counterproductive to safety may cause the exact opposite to occur, since operations may override the safeguard for ease of operational convenience. 

Holland PC (1991) Acquisition and transfer of occasion setting in operant feature positive and feature negative discriminations. Learn Motiv 22 366-387 Imperato A, Mulas A, Di Chiara G (1986) Nicotine preferentially stimulates dopamine-release in the limbic system of freely moving rats. Eur J Pharmacol 132 337-338 James JR, Villanueva HE, Johnson JH, Arezo S, Rosecrans JA (1994) Evidence that nicotine can acutely desensitize central nicotine acetylcholinergic receptors. Psychopharmacology 114 456-462... 

For a Class I or Class II area, a Division 1 location is likely to contain the hazardous condition during normal operations or frequently because of maintenance and repair. A Division 2 location is likely to contain the hazardous condition only under abnormal circumstances, such as process upset or equipment failure. These two divisions, which are based on the likelihood of an atmosphere being hazardous, control or prescribe the design, construction, and operating features of equipment in that area. Engineering practice tolerates lower levels of protection where there is less likelihood of a hazardous material being present. Thus, Division 1 locations require equipment built to higher standards than equipment built for Division 2 locations. 

C) Centrifuge Test. The purpose of this test usually employed for rockets and missile-type fuzes is to check the operating features of the fuze, such as arming mechanism. A brief description of the procedure is given on p IIB-22 of Ref 39)... 

The theoretical aspects and operating features of the propane deasphalting process have been described fully (12, 14, 89). 

Process performance is straightforward and predictable. While commercial plants are comprehensively instrumented, operating features are readily recognizable from simple measurements, particularly of temperatures. Conditions, for instance, around the base of the column and the reboiler allow interpretation of process parameters, reasoning as follows ... 

Any detailed discussion of the theory governing the accumulation of organic components from water by using solid adsorbents is beyond the scope of this review. However, a qualitative theoretical overview of the essence of the methodology is helpful in understanding the operational features and in selecting the proper adsorbent for the accumulation of the desired organic components. 

In the following pages we summarize the main operating features of each of these two methods, the equipment needed, and some applications. 

The bulk of the SFE experiments performed to date were executed with systems typically consisting of a syringe or reciprocating pump, a high-pressure containing sample vessel comprised of HPLC column hardware, and a fused silica capillary restrictor. Extraction vessel temperatures of 40-80°C were usually accomplished using a converted oven or with the use of a thermostatted tube heater (2,3). Instrument manufacturers now offer a variety of commercially available SFE systems that vary in design, operation, features, ease of operation, and limitations. 

Tran and Mujtaba (1997) and Mujtaba et al. (1997) highlighted the operating features and limitations of BED processes for close boiling and azeotropic mixtures. However, the works were limited to the separation of only one key component in the distillate without due regard to the recovery of solvent or the separation of other components in the feed mixture. 

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