Case study operating conditions

In a TEM with STEM attachment it is possible to ob-Q tain diffraction patterns from areas from 50 200 A. That allows in most cases to obtain patterns from individual particles. In order to study the crystal structure of the particle is more convinient to use a non-convergent beam 10 3 rad). This produces sharp spots and avoids interference effects such as the ones described by Roy et al. (9) that makes the interpretation of the data more complicated. Again in this case the operation conditions must be as clean as possible. 

Crystallization of L-SCMC (S-Carboxymethyl-L-cysteine) from DL-SCMC solution, wluch sodium chloride is contained, has been studied for the purpose to develop an optical resolution process by crystallization. In a crystallization process, crystal size and purity and product amount of crystal are important. Grow rates of L-SCMC seeds and surface nucleation of D-SCMC on the surface of L-SCMC seed crystals, which affect crystal size and purity, were reported by Yokota et al. (1). Using an optical resolution process, the product amount of L-SCMC crystal was studied by the decrease of the concentration of L-SCMC in a DL-SCMC solution. In this study, the concentration change of D-SCMC and L-SCMC in a DL-SCMC supersaturated solution, in which L-SCMC seeds were suspended, were observed. The decreasing rate of the concentration of L-SCMC was different depending on whether the solution was classified by dominant component of L-SCMC or D-SCMC. Particular correlative equations were obtained for either case. The operational conditions at which an L-SCMC seed crystal grew without crystallization of D-SCMC were studied by the induction time for surface nucleation of D-SCMC and a method for deciding the volume of crystallizer for optical resolution process was discussed based on the data obtained in this study. 

Boyce, M.P., Gabriles, G.A., Meher-Homji, C.B., Lakshminarasimha, A.N., and Meher-Homji, F.J., Case Studies in Turbomachinery Operation and Maintenance Using Condition Monitoring, Proceeding of the 22nd Turbomachinery Symposium, Dallas, Texas. September 14—16, 1993, pp. 101-12. 

To demonstrate the use of such a comparative cost analysis, the production of a panel was analyzed according to different processes (Fig. 9-6). In these case studies the following conditions existed (1) the panels measured 61 x 91 cm (24 x 36 in.) with the wall thickness dictated by the process and part requirements so that the weights of the panels differed (2) production was at a level of 40,000/yr. (3) the plastics for all panels were of the same type, except that different grades had to be used, based on the process requirements, so that costs changed (4) each panel received one coat of paint, except that the structural foam also had a primer coating and (5) costs were allocated as needed to those processes that required trimming and other secondary operations. 

Most of the published promotional kinetic studies have been performed on well defined (single crystal) surfaces. In many cases atmospheric or higher pressure reactors have been combined with a separate UHV analysis chamber for promoter dosing on the catalyst surface and for application of surface sensitive spectroscopic techniques (XPS, UPS, SIMS, STM etc.) for catalyst characterization. This attempts to bridge the pressure gap between UHV and real operating conditions. 

Ordinarily a company building such a plant would either have a research laboratory or production facility that can provide the correct formula and operating conditions, or it would purchase this information. For this case study a compromise between the two mixes of Table 3E-2 was made. The actual numbers are given in Figures 4E-1, 4E-2, and 4E-3. 

The effect of different operating conditions (e.g. temperature, presence of C02 and water) on the reduction process by H2 was studied in a large temperature range (200—400"C) over the ternary Pt—Ba/y-Al203 catalyst. In all cases, the catalyst was previously saturated with N0/02 mixtures at the same temperature used for the reduction step (Sections 1 and 6 in Chapter 3). 

In the particular case studied in this paper, it is not worth carrying out the reaction under hydrogen transfer conditions to increase the amount of axial epimer, as up to 65% of the thermodynamically unfavoured alcohol can be obtained over Cu/Si02 at 60°C and 1 atm of H2 (5). However, this work shows that the use of secondary alcohols as donors is possible under very mild conditions over the same catalyst. This can be useful both for safety reasons and for operating under mild experimental conditions in order to convert sensitive molecules (such as the ones used in the synthesis of speciality chemicals that can not withstand gas phase conditions). 

Moholkar et al. [11] studied the effect of operating parameters, viz. recovery pressure and time of recovery in the case of hydrodynamic cavitation reactors and the frequency and intensity of irradiation in the case of acoustic cavitation reactors, on the cavity behavior. From their study, it can be seen that the increase in the frequency of irradiation and reduction in the time of the pressure recovery result in an increment in the lifetime of the cavity, whereas amplitude of cavity oscillations increases with an increase in the intensity of ultrasonic irradiation and the recovery pressure and the rate of pressure recovery. Thus, it can be said that the intensity of ultrasound in the case of acoustic cavitation and the recovery pressure in the case of hydrodynamic cavitation are analogous to each other. Similarly, the frequency of the ultrasound and the time or rate of pressure recovery, are analogous to each other. Thus, it is clear that hydrodynamic cavitation can also be used for carrying out so called sonochemical transformations and the desired/sufficient cavitation intensities can be obtained using proper geometric and operating conditions. 

The case studies revealed a lack of overview regarding precursors, their underlying organizational root causes (the latent conditions) and their possible effects on safety barriers. This lack of overview created the opportunity for safety risks in the operational process, despite the presence of many safety indicators and measures. 

In the following sub-Sections the practical approach derived in the previous Chapter will be applied on this case study. Therefore, the precursors present inside the operational process are identified. Then, the control of the operational process will be modelled and analysed to find the ineffective control elements. Furthermore, the latent conditions causing the ineffective control will be retrieved and their impact on the existing safety barriers will be identified. Finally, improvement opportunities for the company will be indicated, together with some recommendations and enhancements for the applied concepts and the proposed practical approach. 

From the four case studies several suggestions for improvement were made, according to the identified latent conditions and specific precursors. However, the implementation and validation of these suggestions was not performed and are recognised as steps still missing in the final validation of the 7-stage protocol. The analysis was performed in close co-operation with company employees and the remedies implemented were derived together with the employees. As Schein (Schein, 1999) clearly states, the success of the remedies depends heavily upon the involvement of the company employees, because they know what will work and are ultimately responsible for the implemented remedy and its consequences. 

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