Monthly Archive: November 2010

Nov
29

Control Loop Foundation – Web Support

A web site accompanies the book Control Loop Foundation – Batch and Continuous Processes. Using this web site it is possible to perform the exercises for the 19 workshops and application examples contained in the book. Also, a video contained under the Solutions tab for each exercise walks you through and explains the exercise. One …

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Nov
26

Reactor Temperature Control Insight of the Day

Portable wireless integral mount RTD temperature transmitters on coolant inlet and outlet can be used for reactor performance troubleshooting or development of a heat removal calculation for an online measurement of reaction rate. The inlet coolant temperature used in the calculation is delayed by a dead time that is the jacket or coil volume divided …

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Nov
25

Secret Installation Effects

On this Thanksgiving Day I am particularly thankful for the advances in technology, low friction packing, smart transmitters, and digital valve controllers. These advances have reduced the measurement and valve position installation errors by an order of magnitude. Most of the effects of installation (process and ambient conditions and installation method and location) have been …

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Nov
25

Reactor Temperature Control Insight of the Day

The controller gain, reset time, and rate time must all be maximized to prevent a runaway reaction. Source

Nov
24

Reactor Temperature Control Insight of the Day

The process deadtime and any secondary process time constant (thermowell or heat transfer surface lag) should be less than 1/10 the positive feedback time constant to provide a window of controller gains large enough to prevent a runaway response for uncertainties in process dynamics and PID tuning. Source

Nov
23

Reactor Temperature Control Insight of the Day

There is a window of allowable controller gains for an exothermic reactor temperature that has a positive feedback response from an exponential increase in reaction rate with temperature where too small of a controller gain will result in a runaway. Source

Nov
22

Reactor Temperature Control Insight of the Day

Exceptionally high controller gains of 5 to 50 can be used for extremely tight reactor temperature control and hence product quality control by virtue of an extraordinarily low dead time to time constant ratio. Source

Nov
22

Control Loop Foundation Class

The book Control Loop Foundation originated from an internal Emerson training class that I put together for new engineers. The Education Services training center located in Austin, TX provided a class room for this training class. I found this to be an ideal training environment for teaching the class since each class room in the …

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Nov
19

Heat Exchanger Temperature Control Insight of the Day

The temperature setpoint rather than the loop temperature measurement must be used in the energy balance calculation of the feedforward signal to avoid positive feedback. Source

Nov
18

Feedforward Control – Deminar 11 Dec 1 Free Book

A copy of Essentials of Modern Measurements and Final Elements in the Process Industry will be given away to an attendee of Deminar 11 “How to Setup and Adjust the Dynamic Compensation of Feedforward Signals” on Wed Dec 1 (10 am CST). We will explore the adjustment of feedforward delay, lead-lag, and gain for the …

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