Dispersed capital cost

Figure 3.3 summarizes mixing for the various types of continuous solution reactors. Eliminating the wall buildup prevalent in nonradial mixed reactors drives the reactor designer from left to right. The choice from top to bottom depends on the product requirements and the degree of temperature and composition dispersion needed to accomplish them, and the capital cost of multiple control zones in series. 

Concentration of feed Particle size of dispersed phese Effluent quality required Capital cost Operating costs Space for equipment Material of construction... 

The annualized costs of the plant may be considered as the sum of operational costs and capital costs. The operational costs include energy, consumption of reagents, labour, and maintenance. The majority of these costs depend more on the feed flow into the plant than on its configuration, and thus are not considered in this analysis. Only the energy costs of mixing the slurry, generation of bubbles, and dispersion were considered. The capital costs include the cost for the banks and pumps, which can be expressed as a linear function of mass flow rates. Thus, the annualized costs are a linear function of the mass flow rates. 

Traditionally, pitch problems were chemically controlled by the adsorption and dispersion of pitch particles by adding fine talc, dispersants, and other chemicals. However, this use of chemicals leads to problems with effluent treatment and environmental pollution. Seasoning of the wood before pulping is another method where the wood is left outdoors for several months. However, these affect the pulp s brightness and yield, which results in an increase in capital cost and land use. Enzymatic control has proven to be a successful alternative, where lipases have shown their ability to reduce the triglyceride content (Farrell et al., 1997). Lipase AYL, produced from C. rugosa and from C. cylindracea, has been successfully used in the pulp and paper industry (Singh and Mukhopadhyay, 2011). 

The solvent should have a low viscosity, otherwise the column capacity will be reduced and the rate of setding of the dispersion will be slow. Sometimes modifiers can be added to the solvent to reduce its viscosity. Also, increasing the temperature of operation will lower liquid viscosity. The solvent chosen must not produce such a low interfacial tension after solute transfer that an emulsion is formed. In addition, the solvent selected should be readily available and inexpensive. Many organic solvents pose special restrictions in their use due to flammability or high vapor pressure. Also, the solvent selected should be nontoxic and noncar-cinogenic and should not corrode common materials of construction, so as to improve ease of handling and reduce capital cost of equipment. 

Elevated Flares See Flares for a general definition. The elevated flare, by the use of steam injection and effective tip design, operates as a smokeless combustion device. Flaring generally is of low luminosity up to about 20 % of maximum flaring load. Steam injection tends to introduce a source of noise to the operation, and a compromise between smoke elimination and noise is usually necessary. When adequately elevated (by means of a stack) this type of flare displays the best dispersion characteristics for malodorous and toxic combustion products. Visual and noise pollution often creates nuisance problems. Capital and operating costs tend to be high, and an appreciable plant area can be rendered unavailable for plant operations and equipment because of excessive radiant heat. 

Smokeless operation can generally be achieved, with essentially no noise or luminosity problems, provided that the design gas rate to the flare is not exceeded. However, since the flame is near ground level, dispersion of stack releases is poor and this may result in severe air pollution or hazard if the combustion products are toxic or in the event of flame-out. Capital and operating cost and maintenance requirements are high. 

Centralized electrification requires massive amounts of capital [10]. The dispersed nature of houses and low potential demand create little incentive for power companies to provide access to rural areas. In addition, extending the grid may be unrealistic due to transmission line costs or hard terrain [5]. Thus, in rural areas, off-grid and mini-grid solutions make the most sense. Such systems can consist of a single home or several small homes and businesses. The systems can be incremental and scalable and applied to many different conditions and environments [10]. Off-grid and mini-grid options for renewable electricity include solar, wind, clean biomass, and micro-hydro. These options for renewable power will be discussed in more detail below. 

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