Temperature control finger

The simplest approach to investigate the potential of melt crystallization is the so-called bottle test. The feed mixture (molten or has to be molten) is filled in a glass bottle or flask. Thereafter, the flask is cooled slowly in a temperature-controlled bath or is allowed to cool at ambient conditions or, if necessary, in a freezer. Only a part not all has to be solidified Quite often, already a color shift clearly indicates a separation. However, to determine the quality of the purification, for instance by distribution coefficient, the residual melt has to be separated from the crystallized portion by decanting. Finally, the solid, the residual melt, and the feed material can be analyzed to decide whether melt crystallization is suitable as purification technique or not. The advantage of the bottle test is that it is quite simple. Only lab equipment is required to obtain the desired answer concerning the feasibility of melt crystallization. In case the result is positive, everything is clear. If the result, however, is not positive, a more detailed examination technique is required, for example, the cold finger experiment. 

In the MBR, the applicator of plate steel was an important safety feature in the possible event of vessel rupture or explosion. Temperature and pressure measurements, stirring, infinitely variable control of microwave power input, the cold-finger, as well as a pressure relief valve, have all contributed significantly to the safety and reliability of the system. 

Transfer the soil sample to a suitable metal tray to form a thin layer and, as far as possible, remove any stones present. With very heavy soils it is necessary to break any clods between the fingers. Dry the soil by placing the tray in a current of air at a temperature not exceeding 30°C. With large numbers of samples it is convenient to place the trays on a series of metal racks over which air may be blown from thermostatically controlled fan heaters. Continue the process until the soil feels quite dry. If the soil appears to contain moisture after grinding, return it to the drying rack. 

Figure 5.7 Three-dimensional drawing of the experimental system used to assess the catalytic properties of the amorphous iron silicate smokes. The (smoke) catalyst is contained in the bottom of a quartz finger (attached to a 2L Pyrex bulb) that can be heated to a controlled temperature. A Pyrex tube brings reactive gas to the bottom of the finger. The gas then passes through the catalyst into the upper reservoir of the bulb and flows through a copper tube at room temperature to a glass-walled observation cell (with ZnSe windows) in an P iiR spectrometer. From there, a closed-cycle metal bellows pump returns the sample via a second 2L bulb and the Pyrex tube to the bottom of the catalyst finger to start the cycle over again (Hill and Nuth 2003).

The flat-bottomed design of the KLF 2000 bioreactor affords a higher stirrer speed to prevent sedimentation of cells compared with the round-bottomed NLF 22 bioreactor (see below). For cultivation of shear-sensitive cells, round-bottomed bioreactors may be necessary. To avoid high temperatures near the heat finger, a power control unit is used to restrict the power to the range 800-200 W but as low as possible to maintain a temperature of 37°C. In addition to this, heating is restricted to intervals of a few seconds only and the glass part of the bioreactor is insulated. 

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