Intelligent control valves

The intelligent control valve system (ICVS) is a recent innovation which differs from smart devices (see Section 6.12.S) in that it is a combined module which is able 

Intelligent control valves have found increasing application in processes which involve high-value materials and high labour costs such that their higher price can be justified. 

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Control the temperature of a batch reactor with one intelligent controller, instead of a slew of gages, valves and motors. 

The major benefit to be realized from Fieldbus and intelligent instruments is primarily due to the ability to obtain on-line diagnostic information. This provides information on the performance of a control valve, for instance, or on the expected lifetime of a seal material based on the number of hours installed and the duty. These features lead to better planned maintenance (rather than preventative or run-to-breakdown maintenance), which in turn leads to lower overall maintenance costs and fewer unplanned losses of production. Validation of the on-line diagnostics will assist in the ongoing review of the validation status of the OCS. 

Distributive controi systems combine some of the most innovative technologies into an interactive network of intelligent microprocessors, application software, and communication networks. The hardware for a DCS includes a host CPU or programmable logic controller (PLC), intelligent field devices (transmitters, controllers, and control valves), remote CPU, and keyboard. This type of system offers the highest level of operator interaction. 

Since final element is the weakest link, so ptopet selection of the same is exttemely important. The following three configurations are very popular. In all cases, control valves are equipped with intelligent valve positioner (IVP). 

Intelligent control systems are not just available for thermoplastics, but also for thermosets and elastomers. Other control systems are used for example for the automatic and melt front-dependent opening and closing of valve gates in liquid silicone injection molding. 

This device operates as a control valve positioner but is also an intelligent device with Hart communications. As shown in the diagram the positioner copies its alarm and testing status into the Safety PLC or into a DCS. 

The fieldbus approach to distributed control is shown in Figure 15.16. Control is distributed to intelligent field-mounted devices (i.e., sensors, valves, and controllers with onboard microproces-... 

Another direction of research could be the use of temperature-sensitive hydrogel thin films to allow fluid control in nanofluidics. Below the LCST these layers will be hydrophilic and above the LCST significantly more hydrophobic. It should be possible to make intelligent hydrophobic patch valves that aie switched by temperature. 

Fig. 7.4 An intelligent active system to monitor and adjust combustion in engines. A sensor (electrochemical cell) monitors the partial pressure of oxygen, its output voltage depends on the ratio of partial pressure of oxygen in air (po2 (ref)) to partial pressure of oxygen in the combustion gas (po2(exhaust An increase of po2(exhaust at incomplete combustion is indicated by the sensor with increased voltage V. In response, the control component sends a voltage signal to the actuator. Thanks to the reverse piezoelectric effect (see Pig. 5.6b) the actuator expands and sets ajar the valves supplying fuel to the engine...

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