Estimating typical factors

Analytical models using classical reservoir engineering techniques such as material balance, aquifer modelling and displacement calculations can be used in combination with field and laboratory data to estimate recovery factors for specific situations. These methods are most applicable when there is limited data, time and resources, and would be sufficient for most exploration and early appraisal decisions. However, when the development planning stage is reached, it is becoming common practice to build a reservoir simulation model, which allows more sensitivities to be considered in a shorter time frame. The typical sorts of questions addressed by reservoir simulations are listed in Section 8.5. 

Typical factors for the components of the capital cost are given in Table 6.1. These can be used to make an approximate estimate of capital cost using equipment cost data published in the literature. 

Table 6.1. Typical factors for estimation of project fixed capital cost...

This study demonstrates that the nonlinear optimization approach to parameter estimation is a flexible and effective method. Although computationally intensive, this method lends itself to a wide variety of process model formulations and can provide an assessment of the uncertainty of the parameter estimates. Other factors, such as measurement error distributions and instrumentation reliability can also be integrated into the estimation procedure if they are known. The methods presented in the crystallization literature do not have this flexibility in model formulation and typically do not address the parameter reliability issue. 

The recommended approach for semi-detailed estimates is to apply the following typical factors used by many contractors in the chemical industry. 

Table 6.4. Typical Factors for Estimation of Project Fixed Capital Cost...

Other averages for boiling points are used in evaluating K and the other physical properties in this Appendix. (Refer to Danbert or Maxwell S for details.) This factor has been related to many of the other simple tests and properties of petroleum fractions, such as viscosity, molecular weight, critical temperature, and percentage of hydrogen, so that it is quite easy to estimate the factor for any particular sample. Furthermore, tables of the UOP characterization factor are available for a wide variety of common types of petroleum fractions as shown in Table K.l for typical liquids. 

Typical emission control systems in coal dryers are cyclone collectors and high-efficiency wet scrubbers or packed towers in series. Fabric collectors are not usually used because of fire hazard. High-efficiency cyclone, a venturi scrubber, and a demister installed on a thermal dryer can reduce PM from 4.5 to 0.1 g/m [64]. The estimated emission factors for coal drying plants expressed as kg/t of coal dried are summarized in Table 53.15. 

Many continuing costs are associated with the operation of a chemical plant. These are included in the cost sheet shown in Table 17.1, which is patterned after one prepared by Busche (1995) and includes representative unit costs (typical factors) that can be used for early estimates when more exact costs are not available. 

Data This type of estimate typically relies on cost information for a conplete process taken from previously built plants. This cost information is then adjusted using appropriate scaling factors, for capacity, and for inflation, to provide the estimated capital cost. 

It should be emphasized that capital cost estimates using installation factors are at best crude and at worst highly misleading. When preparing such an estimate, the designer spends most of the time on the equipment costs, which represent typically 20 to 40 percent of the total installed cost. The bulk costs (civil engineering, labor, etc.) are factored costs which lack definition. At best, this type of estimate can be expected to be accurate to 30 percent. 

Gasohol in the United States. Over 90% of the fuel ethanol in the United States is produced from com. Typically, 0.035 m (1 bushel) of com yields 9.5 L (2.5 gal) of ethanol. Ethanol is produced by either dry or wet milling (87). Selection of the process depends on market demand for the by-products of the two processes. More than two-thirds of the ethanol in the United States is produced by wet milling. Depending on the process used, the full cost of ethanol after by-product credits has been estimated to be between 0.25—0.53/L ( 1—2/gal) for new plants (88). Eeedstock costs are a significant factor in the production of fuel ethanol. A change in com price of 0.29/m ( 1.00/bushel) affects the costs of ethanol by 0.08/L ( 0.30/gal). 

The overall requirement is 1.0—2.0 s for low energy waste compared to typical design standards of 2.0 s for RCRA ha2ardous waste units. The most important, ie, rate limiting steps are droplet evaporation and chemical reaction. The calculated time requirements for these steps are only approximations and subject to error. For example, formation of a skin on the evaporating droplet may inhibit evaporation compared to the theory, whereas secondary atomization may accelerate it. Errors in estimates of the activation energy can significantly alter the chemical reaction rate constant, and the pre-exponential factor from equation 36 is only approximate. Also, interactions with free-radical species may accelerate the rate of chemical reaction over that estimated solely as a result of thermal excitation therefore, measurements of the time requirements are desirable. 

The search for asbestos replacement materials is obviously an ongoing process and further developments in this area are to be expected. The extent of substitution of asbestos fibers by other fibers or other materials has been limited by several factors, typically the availabiHty of adequate replacement materials, the cost performance ratio of such materials, and the uncertainty of long-term health risks of these replacement materials. From the data currendy available, it may be estimated that between 10—20% of the industrial consumption of asbestos fibers was diverted to other materials during the 1980s. 

Direct labor costs can be estimated usiag the flow sheet, typical labor needs (persons /shift) for each piece of process equipment, and the local labor rate. Company files are the best source for labor needs and rates, although some Hterature data are available (1,2). The hourly cost of labor ia the United States can be estimated from the M.onthly l bor Review of the Bureau of Labor Statistics. Production supervision costs can usually be taken as a factor, such as 15% of the direct labor cost. 

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