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 …
Category Archive: Final Control Elements
Dec
19
Maximizing the Return on Your Control Investment – Part 2
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
15
How to Succeed – Part 6
The increased emphasis on minimizing leakage, energy use, and low cost bid has lead to increased process variability. The valve with the lowest leakage, pressure drop, and price tag often has deadband, rangeability, resolution, and sensitivity deficiencies leading to poor control creating continual oscillations even when there are no process upsets. The sustained equal amplitude …
Dec
12
Maximizing the Return on Your Control Investment – Part 1
At Emerson Exchange, 2011, I had the pleasure of working with James Beall, Principal Control Consultant, Emerson Process Management to host a workshop that addresses how to get the maximum return from your control investment. The design and commissioning of the controls associated with a continuous or batch process directly impact plant operating efficiency and …
Dec
08
How to Succeed – Part 5
We continue this series with some helpful hints for control system design and implementation. This week and next week we look at control valve selection. There are a lot of misconceptions from sales pitches that lack an understanding of the need for a valve to have minimum backlash and maximum resolution and sensitivity. Most of this stems …
Nov
21
Does Anyone Share?
At Emerson Exchange, 2011, I had the pleasure of working with Jay Colclazier, Senior Automation Engineer, CHS Refinery, and Joanne Salazar, Global Marketing Communications Manager, Emerson Process Management, to host a workshop that addresses Online Tools for DeltaV Systems Users. This workshop provides an overview of online tools that Emerson provides to help users collaborate …
Nov
07
Interfacing to Motorized Actuator
At Emerson Exchange, 2011, I had the pleasure of working with Tom Pesek, Marketing Manager, Emerson Process Management to host a workshop on Interfacing the DeltaV control system to motorized actuators. The workshop addresses the use of motorize actuators for valves and dampers. These types of actuators may be preferred for some process control applications. …
Nov
04
Secondary Flow Loops Offer a Primary Advantage
A secondary flow loop offers opportunities for feedforward control, identification of valve stick-slip and backlash, online metrics, diagnostics, rejection of pressure disturbances, linearization, and modeling. However, a secondary flow loop can be detrimental when the primary loop has a 63% response time less than 10 seconds. If the 63% response time is greater than 5 seconds, an exceptionally …
Oct
17
Emerson Exchange – 2011
This year Emerson Exchange will be held October 24-28 at the Gaylord Opryland Resort & Convention Center in Nashville, Tennessee. Emerson Exchange is a forum for the free exchange of non-proprietary information among the global user community of all Emerson Process Management’s products and services. The technical sessions in this conference cover a wide range of industry …
Oct
03
Commissioning Control Systems – Increase/Decrease Selection
The analog output block action on loss of power, that is, fail open or fail closed, is defined in Foundation Fieldbus devices through the configuration of the IO_OPTS parameter. Also, as addressed in Control Loop Foundation – Batch and Continuous Processes, this parameter is also used in DCS systems that have adopted the function blocks …
