Mar
01
The IFAC Conference on Advances in PID Control, PID’12, will be held in Brescia, Italy on March 28-30, 2012. As noted on the conference web site, the aim of this conference is to gather academic and industrial experts in the field in order to present the recent research developments in the design of PID controllers. …
Feb
27
Earlier this year, the Namur Working Group 4.15 invited Emerson and four other major manufactures of distributed control systems and wireless transmitters to present their activities and R&D work concerning closed loop real time control applications based on wireless technology. In this meeting with Working Group 4.15, each vendor was given one hour for their …
Feb
20
Work on the WirelessHART specification began over seven years ago. Since that time the WirelessHART specification has been published by the HART Communications Foundation. Also, in 2010 WirelessHART was approved by IEC as an international standard, IEC 62591Ed. 1.0. From the very beginning, the WirelessHART design included the features required for both monitoring and control applications. …
Feb
13
In January I posted a series of four (4) blogs that addressed the implement of an on-line compressor efficiency calculation. The example for this series was a compressor for a refrigeration system that used R134a refrigerant. If you have a similar compressor application in your plant then the information provided in these blogs may act …
Feb
06
The week of January 8th, 2012 I traveled to our office in Costa Rica to teach the 9025 class. This class was created last year by Emerson’s education department to provide training on the basics of process control and instrumentation. The lecture material and student workshops included in the class are based on the book …
Jan
30
Part 1 of the centrifugal compressor efficiency series addressed the measurements and parameters that must be calculated to determine compressor efficiency. In Part 2-3 of this series we examined one way of calculating the enthalpy and entropy of the gas stream at the compressor suction and discharge and isentropic enthalpy for the refrigerant R134a. Once …
Jan
26
A compressor going into stall is like jumping off a cliff with a bungee cord. If the bungee cord has no losses to dampen the oscillation, we have something akin to surge. A 0.5% drop in efficiency can occur for each surge cycle. Several surge cycles can occur due to delays and lags in high …
Jan
23
Part 1 of the centrifugal compressor efficiency series addressed the measurements and parameters that are used to calculate compressor efficiency. In Part 2 of this series we examine how these measurements are used to calculate the enthalpy of the gas stream at the compressor suction and discharged for the refrigerant R134a. This calculation utilized bilinear …
Jan
19
We conclude with a summary on how you can avoid bursts of oscillations, get to setpoint faster, choose the right execution time and filter, coordinate the speed of loops, optimize operations without while protecting equipment, provide a consistent flow response for model predictive control, eliminate limit cycles, and improve analyzer and wireless control loops (all …
Jan
16
As addressed in Part 1 of the centrifugal compressor efficiency series, the enthalpy of the gas stream at the compressor suction and discharge must be known to determine the compressor efficiency. Also, the isentropic enthalpy must be determined based on the gas stream entropy at the compressor suction and the compressor discharge pressure. These properties …
