Supply carefully designed performance

Careful design of the front end (Table 2) can considerably increase the performance. The advantage is most prOTiounced for miniaturized electrodes with low sensitivity. Since the electrode impedance depends considerably on current density, it is advisable to hold the current density constant or the same in the MUT and reference branch, as it is accomplished in Table 2 A (current excitation). A symmetric Howland-type current source supplies both the MUT and the reference with a current of the same amplitude but opposite polarity. Although, a single current source with current mirror can be used as well. Availability of integrated circuits like ADS 129/8130 (Analog Devices) makes the approaches, as shown in Table 2, favorable. 

Startup flow to the expander is designed to be supplied from the discharge of the compressor through a throttle valve and cooler. A careful study of the characteristics of the compressor blow-off valve and the expander startup valve was performed by Solvay process engineers. Based on these calculations, the startup cooler and valve were sized to supply the minimum required flow to tlie expander wheel. 

The following natural precursors have been selected for KOH activation coal (C), coal semi-coke (CS), pitch semi-coke (PS) and pitch mesophase (PM). An industrial activated carbon (AC) was also used. Activation was performed at 800°C in KOH with 4 1 (C KOH) weight ratio, for 5 hours, followed by a careful washing of the samples with 10% HC1 and distilled water. The activation process supplied highly microporous carbons with BET specific surface areas from 1900 to 3150 m2/g. The BET surface area together with the micro and the total pore volume of the KOH-activated carbons are presented in Table 1. The mean micropore width calculated from the Dubinin equation is designed as LD. 

The location, operation, and maintenance of the BSC should be carefully planned. Similar to LFCB, the BSC should be located in an area free of steady or intermittent air currents, which might defeat the laminar airstream by a backwash effect. The BSC should be connected to an adequate power source, having the minimum possible current fluctuation. The effects of voltage variation on cabinet performance can be pronounced (Fig. 10A), causing a variation in intake and supply velocities sufficient to result in an unacceptable unit performance (Fig. lOB), thereby compromising personnel and product protection design features... 

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