Mode Operation Optimisation

During the entire period of the NSSSs operation a supervisory activity has been carried out by the design organization as concerned reactor-related equipment and systems. Each failure or mis-operation event was thoroughly analysed, and recommendations for their elimination were then developed. Remarks of the plants personnel on operation of individual equipment items and systems were analysed and quickly removed new improved arrangements were tested the plants operating modes were optimised, etc. Inspections of equipment were carried out, weak points were identified and then removed in both... 

An open volume, high isolation RF system suitable for pulsed NMR and EPR spectrometers with reduced dead time has been described. It comprises a set of three RF surface coils disposed with mutually parallel RF fields and a double-channel receiver (RX). Theoretical and experimental results obtained with a prototype operating at about 100 MHz have been reported. Each surface RF coil (diameter 5.5 cm) was tuned to 100.00 0.01 MHz when isolated. Because of the mutual coupling and the geometry of the RF coils, only two resonances at 97.94 MHz and 101.85 MHz were observed. These were associated with two different RF field spatial distributions. In continuous mode operation the isolation between the TX coil and one of the RX coils (singlechannel) was about —10 dB. By setting the double-channel RF assembly in subtraction mode the isolation values were optimised to about —75 dB. The described system was selected as a model for potential applications in solid-state NMR and in free radical EPR spectroscopy and imaging. 

In the same procedure, electrolyser elements capable of ODC operation as well as elements in the hydrogen mode are tested in parallel. As a supplementary effect it was seen that the performance of the element (which in the anode half-cell was optimised for the special demands of the thermohydraulics of finite-gap ODC operation) demonstrated excellent operational results. The standardised power consumption of 4kAm-2 remains below 2050 kWh tonne-1 NaOH even after several months of operation. 

Nicoud, R. M. and Perrut, M. in Costa, C. A. and Cabral, 1. S. (eds.) Chromatographic andMembrane Processes in Biotechnology (Kluwer Academic Publishers, 1991) p.381. Operating modes, scale-up and optimisation of chromatographic processes. 

ESI operating in the negative ion (NI) mode has been the interface most widely used for the analysis of anionic perfluorinated surfactants. In addition, ESI has also been optimised for the determination of neutral compounds such as the sulphonamides PFOSA, Et-PFOSA and t-Bu-PFOS. The use of atmospheric pressure photoionisation (APPI) has been explored in few works [78-80]. Takino et al. [78] found as the main advantage of this technology, the absence of matrix effects, but the limits of detection were considerably higher than those obtained by LC-ESI-MS/MS. 

Hoechst has developed a method moulding PP foam automobile air ducts that optimise air flow and also provide good sound and heat insulation. Machines are adapted to suck the parison onto the mould walls rather than to blow mould it. The process also uses a blowing pin operating in reverse mode to create a partial vacuum inside the moulding in order to roughen its inner surface. HOECHST AG... 

Dynamic optimisation of this type of periodic operation was first attempted and reported in the literature by Mayur et al. (1970), who considered the initial charge to the reboiler as a fresh feed stock mixed with the recycled off-cut material from the previous distillation task. Each batch cycle is then operated in two distillation tasks. During the Task 1, a quantity of overhead distillate meeting the light product specification is collected. The residue is further distilled off in Task 2 until it meets the bottom product specification. The overhead during Task 2 meets neither specifications (but the composition is usually kept close to the that of the initial charge for thermodynamic reasons) and is recycled as part of the charge for the next batch. As the batch cycle is repeated a quasi-steady state mode of operation is attained which is characterised by the identical amount and composition of the recycle (from the previous batch) and the off-cut (from the current batch). Luyben (1988) indicates that the quasi-steady state mode is achieved after three or four such cycles. 

Mujtaba (1999) considered the conventional configuration of BED processes for the separation of binary close boiling and azeotropic mixtures. Dynamic optimisation technique was used for quantitative assessment of the effectiveness of BED processes. Two distinct solvent feeding modes were considered and their implications on the optimisation problem formulation, solution and on the performance of BED processes were discussed. A general Multiperiod Dynamic Optimisation (MDO) problem formulation was presented to obtain optimal separation of all the components in the feed mixture and the recovery of solvent while maximising the overall profitability of the operation. 

First, two examples using both problems OP1 and OP2 are presented to explain the effects of different solvent feeding modes and path constraint on the operation. In these examples only Task 1 of Figure 10.6 is carried out where component 1 is recovered at a given purity. Then, example 3 using Multiperiod Optimisation Problem (OP) is presented, where all three Tasks of Figure 10.6 are carried out. 

Here, the same mixture used for example 1 is considered. Semi-continuous solvent feeding mode with full charge strategy is opted in this example. The objective is to maximise the productivity of Task 1 of the STN shown in Figure 10.6. The specification on the distillate composition is 0.95 molefraction in Heptane. The optimisation problem (OP1) is considered and both the reflux ratio and solvent rate profiles are optimised. Again two time intervals are used for the entire operation period (Task 1). In each interval, constant reflux ratio and solvent feed rate are used, the values of which are optimised. The input data are the same as those in Table 10.1 except that the maximum reboiler capacity is 25 kmol. The solvent is introduced in plate 6 (Nf). 

The bio-oil used for the test programme was produced by BTG in Enschede (NL) with the Rotating Cone Technology from poplar as the bio-mass material. As alternative raw materials for pyrolysis wheat straw, Spanish thistle and other wood wastes have been investigated. The main objective of this paper is to demonstrate the power generation from bio-oil in a gas turbine, the optimisation of the combustion behaviour with respect to emissions and operation characteristics and the comparison of emission and operation data from bio-oil and conventional diesel fuel. For technical reasons the gas turbine had to be adapted to the operation in dual fuel mode with the possibility to switch between diesel and bio-oil. 

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