Blending systems digital

Digital blending systems pros ide the mosl accurate means (or automatic, continuous-control flow of bulk materials. They are dependent entirely on the accuracy of the digital pulses Irunsmilicd from the individual weigh feeders—with a control accuracy of plus or minus one pulse. 

FIG 6.11. The output of the controller is the only analog signal in. typical digital blending system. 

The blending system in Fig. 8.1 involves analog instrumentation. For an analog device, the input and output signals are continuous (analog) rather than discontinuous (digital or discrete time). Analog devices... 

The exit composition C3 of the blending system in Fig. E17.18 is controlled using a digital feedback controller. The exit stream is automatically sampled every minute, and the composition measurement is sent from the composition transmitter (AT) to the digital controller. The controller output is sent to the ZOH device before being transmitted to the control valve. 

Under Monsanto s Aroclor nomenclature system, each Aroclor is assigned a four digit number. The last two digits indicate the approximate percentage weight of chlorine in the product and the first two digits indicate the type of material as follows 12—chlorinated biphenyls 25—blend of chlorinated biphenyls and chlorinated terphenyls (75 25) 44—blend of chlorinated biphenyls and chlorinated terphenyls (60 40) and 54—chlorinated terphenyls. 

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