Monthly Archive: February 2011

Feb
28

Ratio Control

For many processes, such as blending and boiler combustion, a key objective is to maintain the flow rates of two process streams in some proportion to one another. In such cases, ratio control may be applied. When ratio control is applied, one process input, the dependent input, is proportioned to the other process input, known …

Continue reading »

Feb
24

Opportunity for Minimizing Loop Interaction

Aggressive action by one loop can upset another loop while attempting fast tight control. The most common example involves loops sharing a common utility or raw material resource, often in piping branches off of a header. The enhanced PID for wireless (PIDPlus) can eliminate the limit cycles that would spread throughout the system. The addition …

Continue reading »

Feb
24

Engineers and Technicians Take a Bow

We owe our health, wealth, and quality of life to engineers, technicians, and scientists. Everything we take for granted today whether it be our car, home, job, media, medical care, recreation, and sports to the innovations and dedication of people seeking to advance knowledge and technology. During National Engineers Week it behooves us to realize …

Continue reading »

Feb
21

Valve Position Control

The precise adjustment of process feedstock flow is often necessary to maintain the processing conditions required to meet product specifications. To meet the target plant production rates, a high feedstock flow rate is often required. If a single valve is used to regulate the feedstock flow, then the precision with which the flow rate may …

Continue reading »

Feb
18

Dynamic Reset Limit

I just realized external reset is the key to sustainable manufacturing and in particular abnormal situation prevention and optimization. I knew the PID option “dynamic reset limit” where the external reset signal is a secondary loop PV, variable frequency drive speed, or control valve position, was important. I demonstrated in Deminar # 3 how dynamic …

Continue reading »

Feb
14

Split-range Control

A wide variety of processes may be described as having one controlled parameter and two or more manipulated process inputs. The challenge from a control perspective is that there is no unique set of input values that are required to maintain the controlled parameter at setpoint. One of the most common ways of addressing multiple …

Continue reading »

Feb
11

The Latest in pH Measurement and Control

If you want to learn about wireless pH and how to solve pH measurement and control problems, join me for the ISA Web Seminar pH Control Solutions. Last day to register is Feb 15. This is your chance to learn the latest and help ISA, our technical society, to continue to offer educational services. I …

Continue reading »

Feb
11

Valve Position Control

The lowest cost and quickest implementation of optimization simply adds a PID for valve position control (VPC). This is not to be confused with valve positioners or digital valve controllers (DVC). The VPC for optimization is a PID whose process variable (PV) is typically the largest output or implied valve position of the process PID …

Continue reading »

Feb
08

Virtualization – Real Today, a Reality Tomorrow

Virtualization technology has advanced a lot over the past 10 years. Most IT organizations now make extensive use of virtualization technology to consolidate servers and manage very large numbers of users. Virtualization provides a much improved architecture for isolating applications from hardware changes, securing systems, providing patch management, and improving power management (in large data …

Continue reading »

Feb
07

Override Control

To ensure proper process operating conditions, it may be necessary to maintain some measurable parameters such as vessel temperature, pressure, and level within certain operating limits (constraint limits). The implementation of override control is often the most effective way to maintain the process within its operating constraint limits. Tools are provided in most control systems …

Continue reading »

Older posts «