Plant , typical

Cmshed stone is conveyed by a mbber-belt conveyor and bucket elevator. Fine stone and dust are conveyed by enclosed screw conveyors, air slides, or pneumatic air systems into storage bins and tank tmcks for shipment. For screening, changeable vibratory screens predominate for all sizes from 23 cm to 0.074 mm (200 mesh). Most stone is stored uncovered on the ground in conical stockpiles, suppHed by radial belt conveyors. Such a conveyor can maintain four stockpiles of different sized stone. Large commercial plants typically stockpile stone in 10 sizes ... 

Some oxygea productioa faciHties are built solely to supply Hquid oxygea, and generally Hquid nitrogen and Hquid argon, via tmck to generally smaller customers. These plants typically use a process cycle optimized for total Hquid production. 

A pilot plant typically has significantly more control loops than the average process faciUty. Caution should be used when applying process correlations in the absence of a detailed design. 

Continuous Emissions Monitoring. A key aspect of the new CAAA is the requirement that plants prove their continued compHance to new emissions limits by installing continuous emissions monitoring systems (CEMs). The CAAA imposes new requirements for monitoring NO, SO2, and CO2 levels in a plant s exhaust gas stream. Affected plants typically must gather data from stack monitoring systems, gas analyzers, and the plant s data acquisition system and provide the data in a format approved by the EPA and state regulators. CEM systems must be in place by November 1993 for boilers affected by Phase I of the CAAA, and byjanuary 1995 for plants impacted by Phase II. 

Silicone foam thus formed has an open ceU stmcture and is a relatively poor insulating material. Cell size can be controlled by the selection of fillers, which serve as bubble nucleating sites. The addition of quartz as a filler gready improves the flame retardancy of the foam char yields of >65% can be achieved. Because of its excellent dammabiUty characteristics, siUcone foam is used in building and constmction fire-stop systems and as pipe insulation in power plants. Typical physical properties of siUcone foam are Hsted in Table 10. 

A derivative of the Claus process is the Recycle Selectox process, developed by Parsons and Unocal and Hcensed through UOP. Once-Thm Selectox is suitable for very lean acid gas streams (1—5 mol % hydrogen sulfide), which cannot be effectively processed in a Claus unit. As shown in Figure 9, the process is similar to a standard Claus plant, except that the thermal combustor and waste heat boiler have been replaced with a catalytic reactor. The Selectox catalyst promotes the selective oxidation of hydrogen sulfide to sulfur dioxide, ie, hydrocarbons in the feed are not oxidized. These plants typically employ two Claus catalytic stages downstream of the Selectox reactor, to achieve an overall sulfur recovery of 90—95%. 

A wool combing plant typically comprises the following processes ... 

Ethylene oxide is produced in large, multitubular reactors cooled by pressurized boiling Hquids, eg, kerosene and water. Up to 100 metric tons of catalyst may be used in a plant. Typical feed stream contains about 30% ethylene, 7—9% oxygen, 5—7% carbon dioxide the balance is diluent plus 2—5 ppmw of a halogenated moderator. Typical reactor temperatures are in the range 230—300°C. Most producers use newer versions of the Shell cesium-promoted silver on alumina catalyst developed in the mid-1970s. 

Dehydration The growing use of isopropanol as a clean-rinse fluid in microelectronics produces significant quantities of an 8.5-90 percent isopropanol waste. Removing the water and trace contan ii-nants is required before the alcohol can be reused. Pervaporation produces a 99.99 percent alcohol product in one step. It is subsequently polished to remove metals and organics. In Europe, dehydration or ethanol is the largest pei vaporation application. For the very large ethanol plants typical of the United States, pei vaporation is not competitive with thermally integrated distillation. 

It is difficult to determine the point at which a condensate stabilizer becomes a gas plant. Typically, if the liquid product is sold as a condensate, the device would be considered a condensate stabilizer. If the product is sold as a mixed natural gas liquid stream (NGL) or is fractionated into its various components, the same process would be considered a gas plant. The least volatile NGL stream has an RVP between 10 and 14 and has sufficient light hydrocarbons such that 25% of the total volume is vaporized at 140°F. 

Figure 9-3 shows a typical cryogenic plant where the gas is cooled to -100°F to -150°F by expansion through a turbine or Joule-Thompson (J-T) valve. In this example liquids are separated from the iniei gas at 100 F and 1,000 psig. It is then dehydrated to less than I ppm water vapor to assure that hydrates will not form at the low temperatures encountered in the plant. Typically, a mole sieve dehydrator is used. 

These aggregated, or macro, cui ves are especially useful for policymakers because they show the potential tradeoffs between energy consei vation policies and investments in new supplies. This is otherwise difficult because most energy conservation measures are small, highly dispersed, and cannot be instantly undertaken, while energy supplies (such as power plants) typically appear in a few large units. 

To handle a peak cooling load with a reduced size of refrigeration plant, typically to make ice over a period of several hours and then use ice water for the cooling of a batch of warm milk on a dairy farm. This is also used at main creameries, to reduce peak electricity loads. The available water is very close to freezing point, which is the ideal temperature for milk cooling. 

Steam traps are installed in condensate, mechanical return systems and are a frequently overlooked item for reducing operating costs. Large industrial process plants typically have many hundreds of steam traps installed to recover low-energy condensate and remove (potentially corrosive) air and carbon dioxide. 

Real-time synthesis of operating procedures. Most of the ideas and methodologies, presented in this chapter, are applicable to the a priori, off-line, synthesis of operating procedures. There is a need though to address similar problems during the operation of a chemical plant. Typical examples are the synthesis of operational response (i.e., operating procedure) to process upsets, real-time recovery from a fallback position, and supervisory control for constrained optimum operation. 

It is often used to judge small improvement projects on operating plant. Typically, a pay-back time of 2 to 5 years would be expected from such projects. 

Plants adapted to extreme habitats, such as old fields and granite rock outcrops, and plants typical of early successional stages are relatively radioresistant. 

Station (Distance in km from Treatment Plant) Typical COD Value (gCOD nr3) Average DO Removal Rate r = k-So (g02 nrr2 lr1) fl2 DO Concentration (g02 m-3) Biofilm Thickness (pm)... 

Other plants that treat siliceous copper oxide ores include Panda and Kabolela plants from the same area. The gangue in this ore is composed of argillaceous and siliceous schist. Both plants essentially use the same flowsheet and reagent scheme, as that described for the Kolwezi plant. Typical plant results during treatment of a siliceous ore are presented in Table 19.8. These are average results achieved from 1980 to 1982. 

Bulk Plants, Distribution and Marketing Terminals store and distribute the finished products from the refineries and gas plants. Typically these facilities handle gasoline, diesel, jet fuels, asphalts, and compressed propane or butane. 

Optimization can be applied in numerous ways to chemical processes and plants. Typical projects in which optimization has been used include... 

Precise electrical data acquisition within the industrial electrolytic plant typical of chlorate and chlor-alkali production facilities represents a significant challenge as the precision of the data obtained is usually degraded in an environment characterised by electrical noise induced by rectifiers and by strong electromagnetic fields. In some cases, rectifier-induced noise such as harmonics and switching peaks in the order of... 

In order to ensure a consistent supply of coal for steam generation, plants typically maintain an outdoor 90-day reserve supply. The pUes are usually not enclosed, so the coal comes in contact with moisture and air, which can oxidize metal sulfides to sulfuric acid. Precipitation then results in coal pile runoff with minerals, metals, and low pH (occasionally) in the stream. 

Is there coevolution between mammals and their food plants Herbivorous mammals usually consume many different plant species, and a plant typically is food to more than one herbivore species. Any patterns of coevolution would be diluted, resulting in diffuse rather than narrow coevolution. Even the diets of the koala (eucalyptus) and giant panda (bamboo) are more varied than commonly assumed. The koala feeds on several Eucalyptus species and did not thrive in zoos when fed only one species. The giant panda even includes animals in its diet. Nevertheless, Lindroth (1988) saw coevolution as an attractive hypothesis for some mammals. 

According to the vendor, the setup of all systems in a KB-1 plant typically costs 150,00 to 250,000. A lime treatment plant can cost 4 to 6 million. Average costs of the KB-1 system are 3.00 to 5.00 per 1000 gal. The vendor claims the KB-1 process can cost below one cent per gallon for treatment of acid mine drainage. Costs depend upon metal load and the cleanup... 

The choice of the proper piping concept is essential for a valid multipurpose plant design. The basic requirements for a piping system are, beside corrosion resistance for a wide array of substances, ease of cleanability (due to quality and costs) and, of course, a high degree of flexibility in order to ensure the needed multipurpose character of the plant. Typically, the following approaches are available ... 

An indicative cost structure for a fine-chemical company is given in Table 7.3. The operating schedule also has a significant impact on the production costs. Whereas continuous plants typically run 24 h per day, there is more... 

---