Stack Scale-Up

T. Benjamin, G. Rezniko, R. Donelson, D. Burmeister," IMHEX MCFC Stack Scale-Up," in the Proceedings of the 27th Inter society Energy Conversion Engineering Conference, Vol. 3, San Diego, CA, Aug. 3-7, 1992, Pg. 290, 1992. 

Figure 7-29 Example of Window-Pane-Style Stack Scale-Up of Planar Anode-Supported SOFC to 250 kW...

Overall, the performance of microfluidic cells in terms of power density has already reached or even exceeded the levels of comparable technologies. Performance benchmarks aside, other critical metrics related to utility also need to be addressed in order for this technology to become commercially viable, namely the efflciency/fuel utilization, co-laminar interface stability, and the stacking/scale-up solutions. Although nearly 100 % fuel utilization has been achieved [16], matching this level of efficiency with high power density is a major challenge that has not been realized to date. Further research on recirculation may potentially lead to a... 

For current consoHdation, the basic circuits, used at each of the multiple power take-off points, are stacked into a Christmas tree topology to form a single power take-off terminal pair. Scale-up of these devices to commercial sizes is not expected to be a problem, as standard electrical components are available for all sizes considered. A different type of consoHdation scheme developed (117), uses dc to ac converters to connect the individual electrodes to the consoHdation point. The current from each electrode can be individually controUed by the converter, which can either absorb energy from or deHver energy to the path between the electrode and the consoHdation point. This scheme offers the potential capabiHty of controlling the current level of each electrode pair. 

Z9 = plate stack height in scaled-up column df = diameter of pilot column df9 = diameter of scaled up column SPM = reciprocating speed of pilot column SPMo = reciprocating speed of scaled-up column... 

Cassettes Cassette is a term used to describe two different cross-flow membrane devices. The less-common design is a usually large stack of membrane separated by a spacer, with flow moving in parallel across the membrane sheets. This variant is sometimes referred to as a flat spiral, since there is some similarity in the way feed and permeate are handled. The more common cassette has long been popular in the pharmaceutical and biotechnical field. It too is a stack of flat-sheet membranes, but the membrane is usually connected so that the feed flows across the membrane elements in series to achieve higher conversion per pass. Their popularity stems from easy direct scale-up from laboratory to plant-scale equipment. Their limitation is that fluid management is inherently very limited and inefficient. Both types of cassette are very compact and capable of automated manufacture. 

Another pilot microstructured reactor uses a smart scale-up of the reactor plate dimensions by a factor of 3.3, each for the width and channel length (see Fig. 13). Stacking further plates is here one concept for future production reactors with another tenfold increase in structured area. 

The scale-up was performed with a single ElectroProd Cell with an anode area of 0.4 m2, with an interelectrode gap of approximately 8 mm, with a typical cell voltage of 5.3 V. A further development program is underway which will extend the scale-up to a 20 cells stack (membrane area > 8 m2) of ElectroProd cells. [282a] The details are found in the US Patent, Ref. [265]. 

The value of /jim is determined by the discontinuity in the dependence of cell current on applied cell voltage which occurs when the interfacial concentration approaches zero. The polarisation parameter is convenient in the design and scale-up of electrodialysis equipment. It can be easily measured in small-scale stacks at a given value of bulk concentration and then used to predict limiting current densities in larger stacks at other concentrations. Most stacks use operating values of the polarisation parameter that are 50-70 per cent of the limiting values. 

Australia Ceramic Fuel Cells Limited was demonstrated a 5 kWe laboratory prototype fuel cell system in 1997. Their system has thin sheet steel components as interconnects in a planer fuel cell design. They are currently scaling up to a 25 kWe pre-commercial stack module. 

The electrolyte is very conductive. In my example of 7 separate containers wired in series, there s no charge applied to the middle ones either because they are in series If you wire 7 resistors in series you have 1/7th of the total voltage across each resistor. I wanted to get about 2V dc per cell, and with 7 cells you can use a 14V dc power supply (for example a battery charger). You could scale up to any number of plates, but the voltage across the stack would be higher. If 7 cells produce 7 units of gas with a given current then 100 cells would produce 100 units of gas with the same current, but the voltage across the whole stack would need to be about 2V multiplied by the number of cells. Thus the power consumption increases approximately linearly with the number of plates. 

Despite the advanced technology of the AQUATECH System, its installation is not complex. In fact, it is simpler and less costly than conventional electrolysis processing. AQUATECH Systems need only two electrodes for an entire 100-150 cell unit stack, avoiding complicated busbar arrangements. Furthermore, scale-up and installation of the unit are facilitated by the modular skid mounted cell stack design. 

Lockett M., Simmons M.J.H., Kendall K. (2004) CFD to predict temperature profile for scale up of micro-tubular SOFC stacks. Journal of Power Sources 131, 243-246. 

By replacing the conventional anionic membranes with the novel ones type Neosepta AXE 01 (Eurodia Industrie, Wissous, F see Table II) as coupled to the conventional cationic membranes type CMX-Sb either in a laboratory-scale stack with an overall membrane surface area (Am) of 0.2 m2 (http //www.ameridia.com/html/fss.html) or in a pilot-scale one with Am = 2.5 m2 (Elmidaoui et al., 2002), it was possible to overcome the earlier shortcomings, as shown in Table XIII. Further scaling-up in an industrial... 

The purification process was scaled up 10-fold from 100 to 1000 cm2 of stacked 142 mm disks. The scale-up exhibited a good separation with a 7 log reduction in endotoxin levels. The yield was 98% with a final purity of 98.2%. This process was again scaled up with the modular configuration described previously (Fig. 3). Two 30-layer 4 m2 Q modules were used in conjunction with a 1 m2 C module. The chromatograms appeared very similar to the 1000 cm2 purification. The product purity was found to be 99.7% with < 0.002 endotoxin units per microgram of product and 0.003 pg DNA per microgram of product. The final product exceeded the clinical pharmaceutical specifications for this product. 

Cocurrent downflow with slug or Taylor flow has been most widely used. Other possible designs, e.g., cocurrent upflow and froth flow, have to our knowledge been tested only in laboratory and pilot plant reactors. Consequently, we will focus on downward slug flow, and the main areas of interest are scale-up, liquid distribution, space velocity, stacking of monoliths, gas-liquid separation, recirculation, and temperature control. 

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