Tag Archive: process

Jan
14

Evaluating Control System Performance

The operation of industrial process control systems often involves the control of multiple unit operations with hundreds of measurements and control loops, as illustrated below. Although these systems are designed to automatically archive operational data in an historian, it is time consuming to examine historical data to determine if there has been a change in …

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Oct
22

Continuous Data Analytics – Impact of Transport Delay

When developing a PLS models for quality parameter prediction, the deviation of measurement values from their mean must be shifted in time to account for the time required for a change in the input to impact the quality parameter. Similarly, these delays should be taken into account in the processing of the deviation values used …

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Jun
18

Impact of ISA106 on Process Automation

One of the side discussions at the SC65E WG7 meeting in Meisdorf, Germany, May, 2012 was the work by ISA106 and its potential impact on process automation. The formation of the ISA106 committee was first announced by ISA in May, 2010. Since that time this committee has been very active. The purpose of this committe …

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Dec
05

Commissioning Highly Interactive Process

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 …

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Nov
28

Improving Continuous Process Operation Using Data Analytics

At Emerson Exchange, 2011, I had the pleasure of working with Frank Seibert, Technical Manager and Eric Chen, Associate Researcher, Pickle Research Center, University of Texas at Austin SRP and John Caldwell, Advanced Control Marketing Manage, and Willy Wojsznis, Senior Technologist, Emerson Process Management, to host a workshop that addresses how data analytics may be …

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Sep
26

Commissioning Control Systems – Setting Controller Action

The process gain may be negative or positive depending on the process design. To provide the correct response a feedback control block must take into account the process gain direction—whether to increase or decrease the manipulated input to correct for a control error. For example, the inlet flow to a tank may be manipulated to …

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Sep
12

Commissioning Control Systems – High Order Process Response

The process response to a change in disturbance or manipulated input is often the result of many mechanisms working together and interacting: heat transfer, momentum, inertia, air capacitance in an actuator, and so on. The combined effect of these different mechanisms constitutes a higher order process response. However, response of a self-regulating process often closely …

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Aug
29

Commissioning Control Systems – Process Delay

Single-loop and multi-loop control may be used to address a wide variety of control requirements. However, if a process is characterized by extremely long process delays or by a high degree of process interaction, then other control techniques may be required. The control of quality parameters such as composition is often complicated by large process …

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Aug
22

Commissioning Control Systems – Control Response

In many processes, it is desirable to have an overdamped response. To achieve that response, the proportional gain used in the PID is typically much less than that required for an underdamped or unstable response. When selecting the PID gain, it is important to consider that the process gain may change with the operating conditions. …

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Aug
08

Commissioning Control Systems – Installed Characteristics

From a control perspective, it is highly desirable that the process gain be constant. If the process gain is constant, then the same proportional gain may be used over the entire operating range of the control loop. However, if for example the valve characteristic has not been selected based on the process requirements, then the …

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