Process plant experimentation

Pilot plants are often more hazardous than process plants, even though they are smaller ia size, for many reasons. These iaclude a tendency to relax standard safety review procedures based on the small scale, exceptionally qualified personnel iavolved, and the experimental nature of the research operations the lack of estabhshed operational practice and experience lack of information regarding new materials or processes and lack of effective automatic iatedocks due to the frequendy changing nature of pilot-plant operations, the desire for wide latitude in operating conditions, and the lack of hill-time maintenance personnel. 

For certain types of stochastic or random-variable problems, the sequence of events may be of particular importance. Statistical information about expected values or moments obtained from plant experimental data alone may not be sufficient to describe the process completely. In these cases, computet simulations with known statistical iaputs may be the only satisfactory way of providing the necessary information. These problems ate more likely to arise with discrete manufactuting systems or solids-handling systems rather than the continuous fluid-flow systems usually encountered ia chemical engineering studies. However, there ate numerous situations for such stochastic events or data ia process iadustries (7—10). 

Liquids and Gases For cocurreut flow of liquids and gases in vertical (upflow), horizontal, and inclined pipes, a veiy large literature of experimental and theoretical work has been published, with less work on countercurrent and cocurreut vertical downflow. Much of the effort has been devoted to predicting flow patterns, pressure drop, and volume fractious of the phases, with emphasis on hilly developed flow. In practice, many two-phase flows in process plants are not fully developed. 

For a new process plant, calculations can be carried out using the heat release and plume flow rate equations outlined in Table 13.16 from a paper by Bender. For the theory to he valid, the hood must he more than two source diameters (or widths for line sources) above the source, and the temperature difference must be less than 110 °C. Experimental results have also been obtained for the case of hood plume eccentricity. These results account for cross drafts which occur within most industrial buildings. The physical and chemical characteristics of the fume and the fume loadings are obtained from published or available data of similar installations or established through laboratory or pilot-plant scale tests. - If exhaust volume requirements must he established accurately, small scale modeling can he used to augment and calibrate the analytical approach. 

Mariotti, A., Germon, J.C., Hubert, P., Kaiser, R, Letolle, R., Tardieux, A. and Tardieux, P. 1981 Experimental determination of nitrogen kinetic isotope fractionation some principles illustration for the denitrification and nitrification processes. Plant and Soil 62 413-430. 

Known scale-up correlations thus may allow scale-up even when laboratory or pilot plant experience is minimal. The fundamental approach to process scaling involves mathematical modeling of the manufacturing process and experimental validation of the model at different scale-up ratios. In a paper on fluid dynamics in bubble column reactors, Lubbert and coworkers (54) noted ... 

Equation (3) is ideally suited for the construction of a nomogram which could be used for calculating the throughput of a radiation processing plant under any operating conditions likely to be encountered. Figure 4 demonstrates what such a nomogram would look like. To use this one must first experimentally determine So. Then the values for So/ei are obtained from Fig. 4a. So/S, the reduction factor, is then chosen, and,... 

Unlike relief system sizing for non-reacting systems, a considerable amount of experimental information is normally required for the design of chemical reactor relief systems. It is necessary to assess all the credible maloperations and system failures that may occur on the process/ plant to determine the reaction runaway that requires the largest relief system. The Workbook also summarises the main steps necessary to do this. 

Wright, L., and Ginsburgh, I., What experimentation shows about static electricity, in Vervalin (Ed.), Fire Protection Manual for Hydrocarbon Processing Plants, Gulf Publishing Co, Houston, p. 235, 1973. 

Other work has been mainly concerned with the scale-up to pilot plant or full-scale installations. For example, Beltran et al. [225] studied the scale-up of the ozonation of industrial wastewaters from alcohol distilleries and tomato-processing plants. They used kinetic data obtained in small laboratory bubble columns to predict the COD reduction that could be reached during ozonation in a geometrically similar pilot bubble column. In the kinetic model, assumptions were made about the flow characteristics of the gas phase through the column. From the solution of mass balance equations of the main species in the process (ozone in gas and water and pollution characterized by COD) calculated results of COD and ozone concentrations were determined and compared to the corresponding experimental values. 

Besides analyzing and correlating data by statistical means, the chemical engineer also uses statistics in the development of quality control to establish acceptable limits of process variables and in the design of laboratory, pilot plant, and process plant (evolutionary operation) experiments. In the latter application, statistical strategy in the design of experiments enables the engineer to set experimental variables at levels that will yield maximum information with a minimum amount of data. 

MacGregor and Tidwell (1979) illustrate some of the steps involved in running plant experimentation, building these process and disturbance models, and implementing simple optimal controllers on some continuous condensation polymerization processes. A number of similar applications to continuous emulsion polymerization processes have also been made. 

Unfortunately, the power number only provides a relationship between impeller size, rotational speed, and fluid properties. The power number does not tell whether a mixer will work for an application. Successful operating characteristics for an anchor mixer usually depend on experience with a similar process or experimentation in a pilot plant. Scale-up of pilot-plant experience is most often done for a geometrically similar impeller and equal tip (peripheral) speed. 

Accurate prediction of the volume of a mixture of liquids will usually require experimental data to relate the masses in kmol to the volume in m. For example. Perry et al. (1984) give tabulations for several liquid mixtures found in process plants. In the absence of such data, the simplest relationship is the linear relationship of Amagat s law, already quoted as equation (13.94). The specific volume of liquid component i, t>i (m /kmol) will depend on the temperature, T, of the liquid in the CSTR, so that the liquid volume is given by. 

The experimental setup used in the smdy is comprised of one reservoir (10 L), from where the solution is fed, through peristaltie pumps, into two eolumn reactors (0.57 L). Experiments were simultaneously conducted in both columns. The first one (column A) contained 40 g of ligneous-cellulosic material plus inoculum, and the second column (column B) contained just 40 g of ligneous-cellulosic material. The anaerobic sludge used as inoculum was obtained from the bottom of an upward-flow anaerobic sludge blanket (UASB) reactor fi-om the effluent of a poultry-processing plant. 

Vapor and liquid phases coexist in virtually all areas of petroleum production operations, including reservoirs, wellbores, surface-production units, and gas-processing plants. Knowledge of fluid properties and phase behavior is required to calculate the fluid in place, fluid recovery by primary depletion, and fluid recovery by enhanced oil recovery techniques such as gas cycling, hydrocarbon solvent injection, and C02 displacement. Because of the complex nature of petroleum reservoir fluids and the often complicated phase behavior observed at elevated temperature and pressure conditions, the fluid properties and phase behavior historically have been measured experimentally. The complex nature of the fluids arises because of the supercritical components which are dissolved in the mixture of paraffinic, naphthenic, and... 

The Prototype Plant Nuclear Process Heat (PNP) project was founded in 1972 with the goals of developing HTGRs for high gas outlet temperatures of 950 °C as a source of process heat to test components for heat transfer to the process plant, and to demonstrate processes and experimental facilities for coal gasification. The technical feasibility of a nuclear process heat reactor for the refinement of coal has been established, main components developed, and its basic licensing capability confirmed. Studies on the technical feasibility and economic competitiveness of the processes for nuclear coal refinement were completed in 1987. 

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