Characteristic operator

Although training can provide workers with adequate practice in process control, some elements of expertise develop primarily with operational experience. The degree of skill and experience with stressful process events are two separate PIFs which will be discussed thoroughly in this section. 

Factors Affecting Human Performance in the Chemical Industry 

Example 3.8 Failure to Apply Well Known Knowledge (Kletz, 1994b) 

Scaffolding was erected around a 225-foot distillation column so that it could be painted. The scaffolding was erected when the column was hot and then everyone was surprised that the scaffolding became distorted when the column cooled down. 

Example 3.9. Failure to Realize that Changed Physical Conditions Would Render Safety Systems Ineffective (Kletz, 1994b) 

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Improving the cetane number by additives results in better engine behavior, as would be predicted by the combustion mechanisms in the diesel engine (noise reduction, better operating characteristics, particularly when cold). Nevertheless, concerning certain items such as pollution emissions, it may be better to obtain a higher cetane number rather by modification of the... 

As we have shown previously, obtaining both good cold operation characteristics and sufficient cetane numbers constitutes the principal objective for the refiner in the formulation of diesel fuel. To this is added the need for deep desulfurization and, perhaps in the future, limitations placed on the chemical nature of the components themselves, e.g., aromatics content. 

Single-operator characteristics are determined by analyzing a sample whose concentration of analyte is known to the analyst. The second step in verifying a method is the blind analysis of standard samples where the analyte s concentration remains unknown to the analyst. The standard sample is analyzed several times, and the average concentration of the analyte is determined. This value should be within three, and preferably two standard deviations (as determined from the single-operator characteristics) of the analyte s known concentration. 

Are the single-operator characteristics for this method acceptable ... 

The use of several QA/QC methods is described in this article, including control charts for monitoring the concentration of solutions of thiosulfate that have been prepared and stored with and without proper preservation the use of method blanks and standard samples to determine the presence of determinate error and to establish single-operator characteristics and the use of spiked samples and recoveries to identify the presence of determinate errors associated with collecting and analyzing samples. 

Polymeric cation-exchange resins are also used in the separation of fmctose from glucose. The UOP Sarex process has employed both 2eohtic and polymeric resin adsorbents for the production of high fmctose com symp (HFCS). The operating characteristics of these two adsorbents are substantially different and have been compared in terms of fundamental characteristics such as capacity, selectivity, and adsorption kinetics (51). 

Electrolytic Cell Operating Characteristics. Currently the greatest volume of chlorine production is by the diaphragm ceU process, foUowed by that of the mercury ceU and then the membrane ceU. However, because of the ecological and economic advantages of the membrane process over the other systems, membrane ceUs are currently favored for new production facHities. The basic characteristics of the three ceU processes are shown in Eigure 5. 

Table 9. Design and Operating Characteristics of Glanor Bipolar Diaphragm Electrolyzers...

These multidimensional analyses do not necessarily predict overall generator performance or operating characteristics significantly more accurately than do the qua si-one-dimensional analyses, which are more economical to mn. Thus the latter are used for general channel design calculations, and the more sophisticated codes mainly to deal with more detailed aspects of channel operation. For example, current concentrations at electrode edges can be predicted by use of the more sophisticated codes. This allows appropriate electrode design for the condition. 

In test planning, the number to be placed on test n and the number of failures rmust be deterrnined. The operating characteristic curves in Reference 18 can be used to specify the test, and to control the errors. 

Many competitive programs to perfect a metallic anode for chlorine arose. In one, Dow Chemical concentrated on a coating based on cobalt oxide rather than precious metal oxides. This technology was patented (9,10) and developed to the semicommercial state, but the operating characteristics of the cobalt oxide coatings proved inferior to those of the platinum-group metal oxide. 

A mathematical model of the operating characteristics of a modem HLW storage tank has been developed (60). This model correlates experimental data for the rate of radiolytic destmction of nitric acid, the rate of hydrogen generation owing to radiolysis of water, and cooling coil heat transfer. These are all functions of nitric acid concentration and air-lift circulator operation. 

Oxidation of Carbohydrates. Oxahc acid is prepared by the oxidation of carbohydrates (7—9), such as glucose, sucrose, starch, dextrin, molasses, etc, with nitric acid (qv). The choice of the carbohydrate raw material depends on availabihty, economics, and process operating characteristics. Among the various raw materials considered, com starch (or starch in general) and sugar are the most commonly available. Eor example, tapioka starch is the Brazihan raw material, and sugar is used in India. 

Operational Characteristics. Oxygen generation from chlorate candles is exothermic and management of the heat released is a function of design of the total unit iato which the candle is iacorporated. Because of the low heat content of the evolved gas, the gas exit temperature usually is less than ca 93°C. Some of the heat is taken up within the candle mass by specific heat or heat of fusion of the sodium chloride. The reacted candle mass continues to evolve heat after reaction ends. The heat release duting reaction is primarily a function of the fuel type and content, but averages 3.7 MJ/m (100 Btu/fT) of evolved oxygen at STP for 4—8 wt % iron compositions. 

Summary of Characteristics of Falling Film Continuous SOj Sulfonation Processes. Both concentric and multitubular reactor systems suppHed by competing manufacturers have surprisingly similar operating characteristics organic feedstock loading of ca 0.4 kg/(h-mm) (circumference) for LAB, and ca 0.3 kg/(h-mm) for alcohol ethoxylates an SO concentration of 3.3—5.0 vol % SO for LAB sulfonation, and 2—3% SO ... 

The impedance behavior of a battery can reveal a significant amount of information about battery operation characteristics (34,44). The impedance of an electrode or battery is given by ... 

Current efficiency depends on operating characteristics, eg, pH, temperature, and cell design, and is generally in the 90—98% range. The cell voltage is a function of electrode characteristics and electrolyte conductivity and can be expressed as... 

K. J. Coeling, Operating Characteristics of High Speed CentrifugalHtomi ers The DeVilbiss Co., Toledo, Ohio, 1981. 

Designed to accommodate rectifier amperages from 30 to 150 kA. Cells of various kA ratings vary in the length of cell and number of anodes and cathodes. Operating characteristics vary with current density (30). 

Membrane cells are the state of the art chlor-alkah technology as of this writing. There are about 14 different membrane cell designs in use worldwide (34). The operating characteristics of some membrane cells are given in Table 3. The membranes are perfluorosulfonate polymers, perfluorocarboxylate polymers, and combinations of these polymers. Membranes are usually reinforced with a Teflon fabric. Many improvements have been made in membrane cell designs to accommodate membranes in recent years (35,36). 

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