Equipment design conclusions

The conclusions drawn from this trial indicated vacuum deaeration, employed in the described equipment design, increased the compaction rate, reduced the fines (non-compacted powder), and increased the compact density (R.W. Miller, unpublished notes, June 1996). 

This paper first provides a brief description of the U.S. plutonium immobilization using ceramic processing. A systematic approach for identifying and solving possible technical safety issues is introduced in Section 3. Technical and other broad safety issues specifically associated with the ceramic processing for excess plutonium immobilization are summarized in Section 4. A brief conclusion is given in Section 5. It should be emphasized that the results are preliminary, since at this moment the details of the facility and equipment designs are not yet available. 

Traditionally, the application of the term human error has been restricted to the operators and maintenance personnel at the sharp end, i.e. in immediate contact with the production system. There has also been a tendency to intermix the immediate cause of an accident (i.e. often a human error) with the responsibility for the occurrence, i.e. the person to blame. In a move away from such simplistic conclusions, there is now a trend to extend the analysis to include errors in the decision-making at all management levels of the company. Such analyses may reveal that human errors by operators, in their turn, are caused by poor equipment design, management s tacit acceptance of rule violations, inadequate work instructions and training, etc. It is usually possible to explain an action labelled as a human error fully by the circumstances in which it has occurred. 

Limited Data First, plant data are limited. Unfortunately, those easiest to obtain are not necessarily the most useful. In many cases, the measurements that are absolutely required for accurate model development are unavailable. For those that are available, the sensitivity of the parameter estimate, model evaluation, and/or subsequent conclusion to a particiilar measurement may be very low. Design or control engineers seldom look at model development as the primaiy reason for placing sensors. Further, because equipment is frequently not operated in the intended region, the sensitive locations in space and time have shifted. Finally, because the cost-effectiveness of measurements can be difficult to justify, many plants are underinstru-mented. 

The inadequacy of the worst case model is evident and the statistical nature of the tolerance stack is more realistic, especially when including the effects of shifted distributions. This has also been the conclusion of some of the literature discussing tolerance stack models (Chase and Parkinson, 1991 Harry and Stewart, 1988 Wu et al., 1988). Shifting and drifting of component distributions has been said to be the chief reason for the apparent disenchantment with statistical tolerancing in manufacturing (Evans, 1975). Modern equipment is frequently composed of thousands of components, all of which interact within various tolerances. Failures often arise from a combination of drift conditions rather than the failure of a specific component. These are more difficult to predict and are therefore less likely to be foreseen by the designer (Smith, 1993). 

Therefore, if the desired indoor air quality goals are clearly defined, they will benefit the designers, health and safety professionals, manufacturers of control technology equipment, end users, and other experts who are responsible for maintaining a safe and healthy indoor climate. In conclusion, introduction of the target level process for industrial air quality will benefit both the health sector and the production sector. 

The accident investigation report is the major result of the investigation. In general, the format should be flexible and designed specifically to best explain the accident. The format may include the following sections (1) introduction, (2) process description (equipment and chemistry), (3) incident description, (4) investigation results, (5) discussion, (6) conclusions, and (7) layered recommendations. 

The following conclusions were drawn. Microcalorimetry can be used to evaluate the heat generation characteristics of a solid material directly at the temperature of practical interest. However, in order to determine the worst case, the variability between batches of the substance must be determined which requires a considerable number of tests (over 100 trials in this specific case). Having obtained the heat generation as a function of temperature for with worst case, the safe storage diameter of storage vessels can be calculated and the equipment appropriately designed. 

This short-term pilot-scale evaluation was accomplished by testing various filtration units under the same set of process conditions. Not only did this work result in a final equipment specification, but revealed significant wafer fabrication process changes. The conclusions of this process design project are listed below ... 

The main variables in the operation of atomizers are feed pressure, orifice diameter, flow rate and motive pressure for nozzles and geometry and rotation speed of wheels. Enough is known about these factors to enable prediction of size distribution and throw of droplets in specific equipment. Effects of some atomizer characteristics and other operating variables on spray dryer performance are summarized in Table 9.18. A detailed survey of theory, design and performance of atomizers is made by Masters (1976), but the conclusion is that experience and pilot plant work still are essential guides to selection of atomizers. A clear choice between nozzles and spray wheels is rarely possible and may be arbitrary. Milk dryers in the United States, for example, are equipped with nozzles, but those in Europe usually with spray wheels. Pneumatic nozzles may be favored for polymeric solutions, although data for PVC emulsions in Table 9.16(a) show that spray wheels and pressure nozzles also are used. Both pressure nozzles and spray wheels are shown to be in use for several of the applications of Table 9.16(a). 

FRANK and KOWALSKI [1982] also state Chemometric tools are vehicles that can aid chemists to move more efficiently on the path from measurements to information to knowledge . Another formulation is given by KATEMAN [1988] Chemometrics is the ... nonmaterial part of analytical chemistry . Expressed in other words [BRERETON, 1990] Chemometrics is a collection of methods for the design and analysis of laboratory experiments, most, but not all, chemically based. Chemometrics is about using available resources as efficiently as practicable, and arriving at as useful a conclusion as possible taking into account limitations of cost, manpower, time, equipment etc. . 

In conclusion, be sure you have all the inlet feed production temperature, pressure, and GOR combinations before making your equipment selections and design. I also wish to commend this engineering firm for putting its best people on the project to make corrections. Any engineer would have been honored to participate thereafter. 

PANELIST SIEGEL I would be glad to try to answer that. The question has been raised often about the process plant design and construction capability in the U.S. Will it have the potential to build as many plants as would be necessary to accomplish a substantial synfuels volume by the year 2000 This has been considered a number of times by a variety of groups. The conclusion has been that the process plant industry and the equipment fabrication industry could grow at a sufficiently rapid rate so that, as an example, by the year 2000, it could put in place 50-100 synthetic fuels plants having an average capacity of 50,000 barrels per day each, which would total 2.5-5 million barrels per day of synthetic fuel capacity. 

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