Multi-zone controller

Since 1994 multi-zone control rolls have been in operation with up to sixty supporting elements arranged horizontally close together. These can be individually controlled so that even more precise profile corrections can be made (Fig. 6.68). 

Microprocessor-controlled multi-zone controllers are characterized by the modular design of 1 to 128 control zones in the withdrawable shde-in technique, the simple... 

Different computer designs are used. As an example there are computer coordinator controllers. These groups of controllers are connected together so that they may all be changed at the same time from a single point. Also used are multi-zone microprocessors that monitor temperature, pressure, output rate, etc. that send either independently or coordinated signals from several sensors to achieve a more reliable and efficient performance. The microprocessor has to carry out control and monitoring functions such as ... 

Sheet Die n A heavy-walled, extremely rigid steel structure, bolted to an extruder head, whose inner passages form the molten plastic leaving an extruder screw into the shape of a flat sheet. Most modern sheet dies are of the coat hanger type with multi-zone temperature control, and contain adjustable choker bars and die lips for close control of lateral variation in the sheet thickness. See Coat Hanger Die, Choker Bar, and Flexible-Lip Die. 

An essential feature of this new design is a better controlled gas flow pattern in the coating zone. This is achieved by application of a guiding system in which the gas flow is accelerated, stabilized, and given a precise amount of swirl, which eliminates slugging, often seen in traditional coaters, and stabilizes multi-tube systems. Particles are... 

Recent developments are related to both batch and continuous processes, including environmental monitoring (see Chapter 18). Applications in relatively inaccessible zones such as explosive, nuclear or high-temperature containments require new specific components and a control organization, revealing the considerable repercussions on the structure of future plants. This section attempts to summarize the most significant research of the past few years on remote control of chemical processes. The new concepts, multi-point measurement techniques, associated components, and aspects of real-time measurement techniques are also examined. 

Spectrophotometric measurement of two species (I and II) in process control, (a) Determination with iso-absorbance technique (A, = slide wavelength) (b) representation of an equal background variation only (curves (D and ). Fbr a multi-component determination (curve ) the spectral complementary variation is represented by the hatched zone. 

Modification of catalyst introduction into reaction zone in particular realization of multi-step catalyst introduction into tubular turbulent apparatus ("zone" model) is the convenient way of polymer MM and MMD control [62]. For "zone" model realization in turbulent regime the following conditions should be fulfilled [1, 27, 66] ... 

Reactor power is chosen in the range of 1500-2KX) MW (thermal). Sodium void reactivity effect is (0 to -0.1) x l0 The number of the zones with different enrichment is 2 or 3. A multi-batch loading scheme is assumed. The following reactivity effects are taken into account sodium thermal expansion and void reactivity Doppler effect axial core expansion radial core expansion control rod drive expansion. IPPE provides reactivity worth tables and specifies correlations for calculations of structural feedback effects of reactivity (with reference data). The duration of the LOF scenario to be computed is taken as about KXX) s. 

With regard to temperature control, the multi-fluid capability of PCRs allows the reaction zone to be bounded by several different heat exchange zones. These zones can perform distinct functions, such as preheating and quenching the reactants. If the reaction is endothermic or exothermic then the reaction zone can include a heat exchange fluid which can either add or remove heat. Fast exothermic reactions (e.g. direct oxidations, nitrations) will especially benefit from the precise temperature control available, increasing both yield and conversion. 

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