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
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 …
Jan
09
Centrifugal compressors play an important role within the process industry. In some cases compressor capacity may determine the throughput of a plant. If a compressor is used for refrigeration then any variation in compressor operation may directly impact the temperature control in key unit operations such as flash vessels and exothermic reactors. Also, the compressor …
Dec
22
Given a good measurement and final control element selection, location, and installation, we move on to designing the control scheme and achieving the best loop performance. The control system should minimize process interactions and optimize process quality, efficiency, and production rate. The control loops should minimize disturbances and effectively achieve new operating points. Here is …
Dec
19
As addressed in my December 12th blog posting, James Beall and I presented Part 1 of this presentation on Friday morning at Emerson Exchange, 2011 in a “meet the expert” workshop. Part 2 was not presentation at Emerson Exchange because of time limitation. In this continuation of the presentation we address when it is possible …
Dec
05
At Emerson Exchange, 2011, I had the pleasure of working with Eric Chen, Research Associate, Pickle Research Center, University of Texas at Austin SRP and Willy Wojsznis, Senior Technologist, Emerson Process Management, to host a workshop that addresses commissioning of a skid process that is characterized by a high degree of process interaction. The size …
