Utility-process connections

Many s)mbols are pictorial which is helpful in representing process as well as control and mechanical operations. In general, experience indicates that the better the representation including relative locating of connections, key controls and even utility connections, and service systems, the more useful will be the flowsheets for detailed project engineering and plant design. 

Where contaminants may cause a reaction, careful design is required to minimize the risk of contamination. Corrosion products are a common contaminant selecting appropriate materials of construction is important in these cases. Where the contaminant is present in other parts of the process, routine analysis of feedstreams is important. If water can cause a reaction both design and operational measures may be required. Water may enter the process by many routes (utility connections, faulty tank roof drains, inadequately dried equipment, etc.) all of these must be either designed out or be very well managed via operating and maintenance procedures. 

Buildings, processes, utility lines, process connections, and controls all have appropriate degree of environmental protection (e.g., against freezing or corrosion)... 

There are P I diagrams for individual utilities such as steam, steam condensate, cooling water, heat transfer media in general, compressed air, fuel, refrigerants, and inert blanketing gases, and how they are piped up to the process equipment. Connections for utility streams are shown on the mechanical flowsheet, and their conditions and flow quantities usually appear on the process flowsheet. 

To avoid cluttering up the flowsheet, it is not normal practice to show the utility (service) headers and lines on the process flowsheet. The utility connections required on each piece of equipment should be shown and labeled, for example, CT W for cooling tower water. The utility requirements for each piece of equipment should be tabulated on the flowsheet. 

Redox reactions involve the loss and gain of electrons. By separating the oxidation process from the reduction process and connecting them electrically through an external circuit, many spontaneous redox reactions can be utilized to produce an electrical potential and an electrical current. Devices that perform these functions are called electrochemical cells. In this ChemLab, you will investigate a redox reaction and use it to construct an electrochemical cell. 

It cannot be overemphasized that the principal elements of a sound industrial safety program, with its primary purpose of OSHA compliance, work hazard reduction, assurance of employee/job safety and health, and the evaluation of jobs or tasks (through the ISA or another comparable method), can, in most cases, be achieved through application of the system safety process. The connection between the two programs, while not entirely obvious, is quite understandable, as described above. Perhaps the most important thing to remember here is that the industrial or occupational safety and health professional can utilize the time-proven techniques of hazard reduction and system safety analysis to accomplish the desired goal of both programs ... 

The ideal solution to the drive-address circuitry is to incorporate it directly into the thin-film structure on the glass. TFTs can be fabricated for the active matrix and the drive-address circuitry at the same time. This is already being done commercially for projection LCDs, where the small size and 1000 X 1000-line matrix restricts the number of connections that can be made to the substrate. A 950 to 1000°C process utilizing fused silica substrates (Table 7.1) is used to make the high-performance poly silicon transistors. Larger- area displays utilize the lower-cost flat glass shown in Table 7.6 where the strain point is far below that of fused silica. In this case, a laser recrystalUzation process is used to create high-mobihty silicon films for developmental displays. 

Utdity power distribution grids normally operate at a fixed frequency of 50 or 60 Hz. These frequencies can be utilized directiy for the induction process if the load characteristics are appropriate. If they are not, specific appHcations can be optimized by the use of variable and higher frequencies produced by soHd-state frequency power converters connected between the supply and the load. 

Vibration is both a cause of problems and an effect of equipment problems. The potential destructive force of an out-of-balance load has led to setting lower shutdown limits on the magnitude of vibration than other rotating equipment. Flexible connections for process and utility lines become a must so these vibration problems are not transmitted to connected equipment. Flexible hoses with liners having concentric convolutions (bellows type) avoid the sharp points inherent with spiral metallic liners. By avoiding the sharp point the liner is less likely to cut the exterior covering. 

Can several process steps be carried out in separate processing vessels rather than a single multipurpose vessel This reduces complexity and the number of raw materials, utilities, and auxiliary equipment connected to a specific vessel, thereby reducing the potential for hazardous interactions. 

The two types of lines on a flowsheet are (1) those representing outlines and details of equipment, instruments, etc., and (2) those representing pipe carrying process or utility liquids, solids, or vapors and electrical or instrument connections. The latter must be distinguished among tliemselves as suggested by Figure 1-21. 

The gas turbine shown in Figure 3-7 is an open-cycle type. An open-cycle type gas turbine uses the same air that passes through the combustion process to operate the compressor. This is the type most often used for stationary power unit applications. A typical example of power requirements for an open-cycle type gas turbine would be for the unit to develop a total of 3,000 hp. However, about 2,000 hp of this would be needed to operate its compressor. This would leave 1,000 hp to operate the generator (or other systems connected to the ga.s turbine). Thus, such a gas turbine power unit would be rated as a 1,000-hp unit because this is the power that can be utilized to do external work. 

The ShimTec reactor from Chart Industries [18, 19] is an example of a HEX reactor with diffusion-bonded plates (Figure 12.2). The reactor is composed of three plates one process plate sandwiched between two utility plates. All the units are made of 316 stainless steel, unless stated otherwise. Swagelok fittings are used for all the connections. 

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