Phot scale

However, tools such as these can be used successfully to compare the performance of different activated carbons and to give an indication of the expected lifetime of the filters, and therefore provide a caution to water authorities when increased monitoring of filter effluent water quality might be warranted. Another type of test, the mini-column test, was used successfully by Gillogly et al. [17] to simulate the removal of the musty odor compound MIB in a phot-scale GAC filter over a period of several years. This simple test, described in more detail in a later section, cannot be used to predict the lifetime of a GAC filter, but it can indicate how well a filter would function at the time of sampling if challenged by an unexpected microcontaminant influx. Thus predictive tools such as SBA or RSSCT can be used in conjunction with a monitoring tool, such as the minicolumn test, to allow the confident use of GAC for the removal of problem compounds. 

In olefins separation the main industrial target is the separation of ethylene/ ethane and propylene/propane mixtures. Both separations are performed on high scale by distihation, but the relative volatiles of olefins and paraffins are so smaU that large columns are needed. Steigelmann and Hughes [55] presented the first results of a bench- and phot-scale study of ethylene and... 

In this contribution, the development of MTO processes will be introduced. We win emphasize the mesoscale challenges and the related studies in the DMTO process development, for which we focus on three aspects a mesoscale modeHng approach for MTO catalyst peUet, the coke formation and control in MTO reactor, and the scale-up of the microscale-MTO fluidized bed reactor to phot-scale. A section followed is dedicated to the future directions in MTO process development in terms of mesoscale studies. 

In phot-scale DMTO fluidized bed reactor, the regenerated catalyst normally has very low coke content. As discussed above, such catalyst may not favor the selectivity to light olefins. Therefore, a counter-current fluidized bed configuration is adopted. In this configuration, the regenerated catalyst is injected into the reactor via catalyst distributor from the top of the dense bed, and the coked catalyst is taken from the draw-off bin beneath the gas distributor at the bottom. Thus, the methanol feed from the gas distributor first contacts the coked catalyst, by which a higher selectivity to light... 

In phot-scale MTO experiments, the regeneration of spent catalyst deactivated in the MTO reactor was conducted in a continuous way by circulating catalyst from reactor to regenerator and vice versa. The activity of spent catalyst was then restored in the regenerator. When the steady circulation is estabhshed, and which is most likely the case in pilot experiments. 

As mentioned above, the coke content in catalyst around 7.6—8.5% is favorable in terms of selectivity to ethylene and propylene (ca. 88—89%) as well as methanol conversion (>98.5%). Further check with Fig. 19, we can find that this is corresponding to the TOS of 160—195 min. Under the operation conditions specified in Fig. 19 therefore, a catalyst residence time of 160-195 min is optimal for Hght olefins selectivity in phot-scale experiments. It should be noted that the WHSV influence the catalyst residence time significantly. An estimation of the catalyst residence time is based on RTi = P RT2 WHSV2/WHSV1, where RTi is the optimal catalyst residence time under WFISV, and P is the coefficient obtained from experiments. A simple estimation can be made by assuming as 1. 

It needs to be pointed out that the results discussed above may not necessarily be the same as in the phot-scale experiments where the catalyst circulation between reactor and regenerator is estabhshed. The circulation of catalyst can maintain a steady average coke content but with certain distribution since the catalyst particles will have residence time distribution due to the back-mixing in fluidized bed. This wiU lead to the change of reaction results to certain extent. But the results obtained from microscale fluidized bed reactor can be used to guide the design and operation of phot-scale setup. 

C, almost no steady period can be achieved in terms of methanol conversion. This can be explained as the longer induction period at a lower reaction temperature. Actually, the methanol conversion is only 1% at the initial reaction stage under reaction temperature of 340 °C. When the reaction temperature is above 400 °C, the duration of the steady state for methanol conversion increases to 200 min. Such a long steady period is beneficial for the operation in the phot-scale reactor. Note that the product distribution may change when reaction temperature increases. The selectivity to light olefins (ethylene + propylene) can be maximized above 425 °C. 

For equal hp speed and impellers with geometric similarity, the rotational speed remains the same in spite of the added hquid level. Thus, the power and torque remain the same for the same impellers, speed, and fluid properhes. However, the volume change affects power per volume 1000(2.66 hp)/7000 gal = 0.38 hp/1000 gal (75.0 W/m ). Similarly, the torque per volume is reduced to 1000(3193 in-lb)/7000 gal = 456 in-lb/1000 gal (13.6 N-m/m ). Both changes represent a substantial reduchon in agitation intensity from the phot-scale results. 

System upscaling is the most critical need for MECs (Logan et al., 2008 Zhang and Angelidaki, 2014). Phot-scale MECs have been built to treat domestic wastewater but the energy recovery is only around 50—70% of electricity input, and hydrogen production rate as well as COD removal rate is low (Heidrich et al., 2013 Heidrich et al., 2014). Much has to been done to optimize reactor design and operational parameters in order to make pilot-scale MECs cost-effective and efficient. 

Lee, Y.W., Chung, J., 2010. Bioproduction of hydrogen from food waste by phot-scale combined hydrogen/methane fermentation. International Jomnal of Hydrogen Energy 35 (21),... 

The AMl/d-PhoT model [33] is a parameterization of a modified AMl/d Hamiltonian developed specifically to model phosphoryl transfer reactions catalyzed by enzymes and ribozymes for use in linear-scaling calculations and combined QM/MM simulations. The model is currently parametrized for H, O, and P atoms to reproduce... 

As a basic in B LMs for the wastewater treatment the author presents two-phase partitioning bioreactors. He presents the main criteria which must be considered in the selection of the LM solvent biocompatibility (toxicity of the solvent to the microorganism), bioavailabihty (resistance of the solvent to biodegradation by the microorganism used), immiscibility in the aqueous phase, high solubility of pollutant in the solvent, favorable mass-transfer characteristics, etc. Biodegradation mechanisms and kinetics are discussed. Apphcations of bioreactors in wastewater treatment in laboratory, phot, and industrial scale are reviewed. Potential applications are considered also. 

At 25°C this reaction is first-order in A in the forward direction with = 0.112 s . In the reverse direction, the reaction is pseudo-first-order in the lactone with = 0.042 A s . This reaction is being studied on a phot-plant scale in a single well-stirred tank reactor (volume =1.5 m ). 

A third and final example of problematic scale-up occurs in the production of maleic anhydride by the partial oxidation of butane with air. This was selected to illustrate the pitfalls of scale-up without appropriate reactor-level models. AH of the excellent work in catalyst development and on proper selection of the best reactor type was nuUified by expecting the scale-up to be based on established rules-of-thumb and using empirical models to fit phot-plant performance data. 

Table 3.1 The popularity of solvents at phot plant scale within GSK. ...

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