Are your control loops operating at their full potential?
Research has shown that in most plants, two out of three of all the control loops are underperforming. Top Quartile performers focus their investments on improving control loop performance.
Typical gains are:
4-8% increase in throughput
5-10% reduction in energy costs
40-80% reduction in quality variations
1-5% increase in equipment availability.
Fact: A survey of almost 5,000 control loops has revealed: Only 1 in 5 loops are well tuned 1 in 6 loops of control loops have Default Tuning 1 in 3 loops have Suspect tuning
Who are we?
Lakeside has a dedicated process optimization team with over 60 years experience.
This team has worked in a wide range of industries including:
Power & Steam generation
Food and beverage
Water and wastewater
Their in-depth expertise in processes, control strategies, instrumentation, and modern loop tuning techniques will help you become a Top Quartile Performer.
Your Road Map to Becoming a Top Quartile Performer
With our Optimization Experts, Lakeside will successfully guide you on your optimization journey. This journey consists of four stages:
Lakeside Tuning Index
Recommendations and Optimization
Monitor and Assess
Step 1: Lakeside Tuning Index (LTI)
The LTI will benchmark the current parameters in your DCS against the industry average. This is the first step in the optimization journey.
The LTI is a proprietary database tool which provides a high-level assessment of the current PID tuning in your control system. Your LTI is compared to almost 5000 other control loops; your results are benchmarked to the overall industry average.
How is the LTI generated?
The LTI is generated using our proven methodology. We extract the data directly from your DCS database to ensure the data is relevant. We do a comprehensive review of key parameters such as: tuning parameters of each active control loop and rate them as "good," "questionable," or "suspect".
The LTI will also analyze other parameters associated with your control loops such as:
Excessive PV filtering. This could indicate a measurement issue.
Non-linear PID features. This could indicate valve related issues.
Use of Derivative
Slow scan rates
Generating your LTI dashboard is a FREE SERVICE
This dashboard shows that 90% of the control loops have duplicate tuning. This means that two or more PID blocks have the exact same tuning. This is a key indicator that most of these control loops have likely never been properly analyzed and tuned.
This dashboard shows that almost 45% of the control loops have Default Tuning, consequently, they have NEVER been tuned.
These two dashboards immediately show optimization opportunities
Step 2: Discovery Phase
The onsite discovery phase is the next step in the journey, where our experts take the results of the LTI and do a deeper dive into your process. Your LTI dashboardwill outline the key focus areas for immediate improvements and provides a guideline for the onsite Discovery Phase.
Process data will be collected, analyzed and compiled in a comprehensive report that will detail recommendations for improvement and, where possible, the potential ROI for each recommendation.
Step 3: Recommendations & Optimization
A series of recommendations will come out of the Discovery stage.
These recommendations will cover:
Control Strategy modifications
Processes are often designed from mass/energy balance point of view; process dynamics and control loop interactions are rarely considered. Modifying the piping or the process can improve the efficiency of the controllers while maintaining the overall mass and energy balance.
The first step during the Discovery Stage is to examine and walk down the process equipment. In this example, a pH controller was analyzed. The caustic addition was done at the outlet of a tank in Building #1. Building #1 required Intrinsically Safe instrumentation whereas Building #2 did not. Consequently, the pH was measured in Building #2.
The lengthy piping distance between caustic addition and the pH sensor introduced 150 seconds of process time delay. This long delay made controlling the pH very difficult, resulting in having the operator putting the controller in Manual mode.
This lack of control caused quality issues
It was recommended that the process design by modified by installing a slipstream along with a pH sensor that was Intrinsically Safe.
This reduced the process time delay, making the pH controllable.
Control Strategy Modifications
Modifying the control strategy can reduce control loop interactions and improve process stability.
Example: Boiler Feedwater Pump
In the Discovery Stage, the data showed that the flow curve tapered off as the valve opened. The process sensitivity decreased to a point where the flow controller was too sluggish at the upper end.
This was confirmed by observing the discharge pressure versus the feedwater flow.
The primary recommendation was to replace the worn-out pump. However, the lead delivery time for this mammoth pump was over 52 weeks.
The interim solution was to install a characterizer between the output of the PID block and the valve.
The end result was a linearized flow curve. This would ensure that the controller tuning response was the same throughout the full range of the PID output.
FACT: 30% of control related issues involve a poorly functioning control valve!
Instrumentation must be properly specified, installed and maintained. A control loop is only as effective as its primary elements. Faulty or poorly performing control valves are a large source of process variations and present some of the greatest opportunities. Moreover, improperly installed transmitters can lead to control loop underperformance.
In the Discovery Stage, the data showed that this chemical injection control valve had 10% backlash or hysteresis.
This translated into a control imprecision of 70 GPM or 32% when compared to a flow controller setpoint of 215 GPM.
This valve imprecision caused significant product quality problem and overdosage.
FACT: 1 in 3 control loops have 'suspect' tuning.
Only 1 in 5 control loops are properly tuned. Improperly tuned control loops will not reduce process variations effectively and potentially even increase process variability.
Lakeside offers courses on proper loop tuning techniques, CLICK HERE for more information.
Example: Loop Tuning
Following the ‘Recommendations’ path, control loops will benefit will be optimized. Typically, this is done using the EnTech Toolkit. This toolkit will collect, analyze and calculate and manage the tuning parameters.
In this example, the level controller was tuned improperly. This caused the inflow to oscillate and destabilized upstream control loops.
The level controller tuning was then calculated properly retuned to prevent level and flow oscillations.
Step 4: Monitor & Assess
Degradation of control loop performance can be slow and insidious. Once a control related problem has been detected and identified, it has been occurring for a long time.
This phase will monitor your control assets on a periodic basis and track their performance. Top Quartile performers use this predictive monitoring program to ensure maximum performance from their control loops.
Remote access to your DCS is a safe and cost-efficient solution to monitor the ongoing performance of your control loops.
Automatic Control Loop Performance Monitoring
For our DeltaV customers, an additional monitoring step can be incorporated by applying a continuous loop performance package called DeltaV Insight. This program will continuously monitor certain dynamic aspects of selected control loops. It will provide several metrics including the following:
Percentage of time the control loop is not in its normal mode.
High process oscillations
If you're interested in transforming your data into actionable knowledge, get in touch with an expert today!