Mixer time-pulsing

Mixer 83 [M 83] Time-pulsing Cross-flow Micro Mixer (I)... 

Mixer type Time pulsing cross- Channel width, 200 pm, 120 pm... 

Figure 1.169 Schematic of the time pulsing cross-flow mixer [48],...

Mixer type Time pulsing cross-flow mixer Top plate Pyrex... 

A microwave pulse from a tunable oscillator is injected into the cavity by an anteima, and creates a coherent superposition of rotational states. In the absence of collisions, this superposition emits a free-mduction decay signal, which is detected with an anteima-coupled microwave mixer similar to those used in molecular astrophysics. The data are collected in the time domain and Fourier transfomied to yield the spectrum whose bandwidth is detemimed by the quality factor of the cavity. Hence, such instruments are called Fourier transfomi microwave (FTMW) spectrometers (or Flygare-Balle spectrometers, after the inventors). FTMW instruments are extraordinarily sensitive, and can be used to examine a wide range of stable molecules as well as highly transient or reactive species such as hydrogen-bonded or refractory clusters [29, 30]. 

Figure 2 graphically represents the blending of dry materials at various mixer and chopper speeds by plotting the product temperature, air temperature above the product bowl, and vacuum versus time. The mixer and chopper were in continuous operation with var iable values from the beginning of mixing untiI approximately 13 minutes into the process. At that time, the mixer and chopper were stopped and pulsed (P) for 3 seconds at 50 RPM at various time intervals. 

Fig. 3.2 The operation of flow methods. The distance x and the combined flow rate govern the time that elapses between mixing and when the combined solutions reach the observation, or quenching, point. In the stopped flow method, observation is made as near to the mixer as is feasible, and monitoring occurs after the solutions are stopped. In the pulsed accelerated flow method, observation is within the mixer.

The pulses produced by this action proceed thru mixer circuits to an oscillograph where they are displayed on a cathode-ray oscilloscope screen along with time calibration markers. This display is photographed and detonation rates are computed from expl increment lengths, and measurements of time displacements are read on a film reader... 

Pulsed continuous flow is a method in which continuous flow is established for a short time. This method can reduce reagent consumption to 5 ml, and fast jet mixers have lowered the accessible reaction half-time to the 10 ps range. Pulsed accelerated flow may be viewed as an adaptation of pulsed continuous flow in which the flow rate through the mixer and observation chamber is varied during the course of one kinetic run. This method can be used for reactions with half-times down to 10 ps. This method is limited to first-order reaction conditions. 

Conventional solvent extraction contactors, mixer-settlers or pulsed columns, have been used exclusively until now for the Pu-U partitioning step. Centrifugal contactors have been considered, but there has been some concern about the compatibility of short residence time with the kinetics of plutonium reduction. 

The exhaustive U, Pu extraction step is best achieved in pulsed columns rather than in mixer settlers in order to keep the contact time lower at the very high radiation level. This operation is expected to produce as its main product a HAW raffinate that is virtually free of Pu (and Np, U) a scrub appears therefore superfluous and would dilute only the HAW. In order to attain still a good extraction efficiency within a few stages, A/O phase ratios < 3 should be avoided. This ratio corresponds to a TBP saturation by heavy metals of about 18%. Considerable amounts of Zr are therefore co-extracted, being however present essentially as inactive isotope. Either a complexing or a reductive stripping is advisable in order to keep the aqueous flow small and the acidity sufficiently high to avoid hydrolysis of Zr. 

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