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 …
Category Archive: Measurements
Feb
13
Monitoring Turbine and Compressor Operation
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 …
Dec
01
How to Succeed – Part 4
We continue this series with some helpful hints for control system design and implementation. This week we look at measurement location and selection. Since a control system deals with change, the prevalent theme is how to improve the detection and correction for change. In the coming weeks we will take a look at control valves …
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
12
Reactor Cooling and Heating Systems – Part 2
Whether the secondary loop uses coil or jacket inlet or outlet temperature is often a matter of tradition for a particular company or process industry. The dynamic response of the cascade control system to reactant disturbances such as feed and reaction rate are the same for jacket inlet and outlet temperature control. However, the coil or …
Sep
01
Chance of a Lifetime
We have the opportunity to hear the 3 most influential and knowledgeable technical leaders in industry give their assessment of the present state and future of our profession. This will be the first and most likely only time these guys will be sharing their knowledge at the same event, thus covering the complete spectrum of …
Aug
25
Top Twelve Mistakes in pH System Design
The extreme capability of the pH measurement and the broad spectrum of applications and process conditions create exceptional requirements for electrode design, mixing uniformity, control valve precision, deadtime minimization, nonlinearity compensation, and control strategies. pH loops are often the most challenging loops in the plant. Slight deficiencies in the mechanical, piping, process, measurement, and control …
Aug
04
Effect of Mechanical Design – Pumps and Piping
The increasing emphasis on saving energy and capital costs can lead to pump and piping designs that inadvertently cause a severe loss of turndown in flow loops and a significant increase in noise , delay, and lag in temperature and pH loops. The deterioration in loop performance can create an insidious reduction in process efficiency …
Jul
21
Top Ten Limitations – Analyzers
Ultimately what we most need to know in each key process stream is the operating condition least measured; composition. We are largely flying blind. Neural networks and projections to latent structure technologies have proliferated because online and at-line analyzers are missing. Here is a look at the use of analyzers in the process industries. Advanced process control (APC) …
Jul
11
Commissioning Control Systems – Input Filtering
The method used to process analog inputs and outputs is unique to each control system. Also, controller and IO bus design influence how often measurement and outputs are updated and thus dictate the control execution rate that is supported by the control system. Understanding the limitations imposed by the basic control system design (i.e., controller …
