Industrial system

The nature of potential exposure ha2ards of low level microwave energy continues to be investigated (116—118). In the United States, leakage emission from microwave ovens is regulated to the stringent limit of 5 mW/cm at 5 cm (119). There is no federal limit on emission from industrial systems but the IMPI has set a voluntary standard which specifies 10 mW/cm at 5 cm (120). Emission values are equivalent to personnel exposures at several meters, well below limits that had previously prevailed in eastern Europe. This conclusion, derived for microwave ovens, should be vaUd for all microwave systems (121). 

The system shown in Fig. 11-75 is direct expansion where diy or slightly superheated vapor leaves the evaporator. Such systems are predominantly used in small applications because of their simplicity and light weight. For the systems where efficiency is crucial (large industrial systems), recirculating systems (Fig. 11-77) are more appropriate. 

Cleaning membranes to restore their efficiency is normal in UF. Food and dairy systems require daily cleaning in any event for hygiene more frequent cleaning is economically intolerable. A few industrial systems operate for six months between cleanings. Cleaning shortens membrane life, and it is often the major determinant of membrane-replacement frequency. 

Metal-reducing bacteria, such as those that convert ferric to ferrous ion, have been suggested as an accelerant for steel corrosion in oxygenated waters, lb date, evidence of these bacteria influencing corrosion in industrial systems is scarce. 

Hence, copper heat exchanger tubes handling acetic acid can he more seriously corroded at low temperatures than at high temperatures. Sulfuric acid at room temperature is handled routinely in carbon steel drums and tanks when water concentration is low, but it becomes extremely corrosive as water concentration increases. As ferric-ion concentration increases during acid cleaning of industrial systems, the corrosion rate of steel increases rapidly. 

Blower, R.W., Cornick, K.J. and Reece, M.P. Use of vacuum switchgear for the control of motors and transformers in industrial systems. Electric Power Appliciitions. 2. No. 3. June(1979)... 

This chapter is organized into four sections, which comprise four complementary approaches to human error in industrial systems ... 

Despite these difficulties, the issue of cognitive errors is sufficiently important that we will describe some of the approaches that have been applied to process industry systems. These techniques can be used in both proactive... 

GE Motors and Industrial Systems, Bui. GEA-12333A, General Electric Co. 

Some desirable characteristics of fluid power systems when compared with mechanical systems. A fluid power system is often a simpler means of transmitting energy. There are fewer mechanical parts than in an ordinary industrial system. Since there are fewer mechanical parts, a fluid power system is more efficient and more dependable. In the common industrial system, there is no need to worry about hundreds of moving parts failing, with fluid or gas as the transmission medium. 

It is impossible to generalize about types of filter to be used. Selection depends on the system, the rate of contamination build-up and the space available. However, a common arrangement is to have a full-flow filter unit before the pump with a bypass filter at some other convenient part of the system. Many industrial systems working below 2000psi can tolerate particles in the order of 25-50 microns with no serious effects on either valves or pumps. 

A larger scale example is the involvement of the cement industry in the growing field of industrial ecology. This takes the idea of an ecosystem with its many intersecting loops of materials and energy and applies it to industrial systems. Why use virgin raw materials and take them through a linear system to produce waste, when an imused material from one industry can be a feedstock for another ... 

Volatility is the key technical problem with many chlorine alternatives such as ozone and chlorine dioxide because most industrial systems are open to the atmosphere and the... 

Lower chemical reactivity with non-target molecules is useful for another performance-related reason. Microorganisms prefer the protection and luxuriant environment in biofilms (the adherent microbial communities that cause detrimental surface-fouling effects in water cooling systems). Most (>99%) of the viable microorganisms in industrial systems are found in biofilms, not floating around freely in the bulk recirculating water. Compared to unstabilized chlorine or bromine, STABREX more effectively removes and disinfects biofilms as shown in Table 6. 

Also, in the 1990s, the Environmental Protection Agency began to focus on pollution prevention. The idea was to cut pollution using natural ecosystems as a model. Industrial systems should not be open-ended, dumping endless byproducts, but closed, as nature is, continuously cycling and recyling. This concept includes life cycle assessment (LCA) which considers ... 

With values between 13 and 16, the equilibrium constant is still high enough to regard the formation of DEG from EG to be irreversible in an open industrial system. DEG formation is not only an important side reaction during esterification, polycondensation and glycolysis, but also during distillation of EG and water in the process columns. In particular, the residence time in the bottom reboiler of the last separation column is critical, where the polycondensation catalyst and... 

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