Trending Does the Trick

Charting real-time data helps improve process control at chemical plant in Pasadena, Texas. Statistical process control data are an important part of day-to-day decision-making.

By Sandra Schiller

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In December 2001, Ethyl Corp., Richmond, Va., implemented a Laboratory Information Management System (LIMS) that automatically plots the latest laboratory test results at their Pasadena, Texas, plant. The new software helps process operators and operations supervisors keep their fingers on the "pulse" of the plant. The new LIMS also gives laboratory and plant personnel the ability to determine the status of any sample in seconds, and provides laboratory management the tools to manage their backlog.

"The ability to monitor plant processes has significantly improved since we installed the new LIMS," says Paul Cook, laboratory coordinator at Ethyl. "We have made other improvements simultaneously so we can't attribute the entire improvement to the LIMS, but it's clear that it has made a significant contribution."

Ethyl Corp. develops, manufactures, blends and delivers additive technology for fuels and lubricants worldwide. The performance benefits of fuel additives include octane and cetane enhancement, emissions reduction, increased lubricity, storage stability and protection against deposits in fuel injectors, intake valves and the combustion chamber. Its lubricant additives help protect engine and other moving parts from wear, deposits, corrosion, water and high operating temperatures.

 

Personnel can easily obtain all of the information associated with this sample from the Process Scheduler. Although all of the data are within the limits, which are represented by the red lines, the sharp change may indicate a problem.

Abandoning manual trends

The Pasadena plant has a history of continual improvement. Statistical process control data are an important part of day-to-day decision-making in the plant, and the ability to efficiently gather and organize these data has become increasingly important.

The plant originally shared the cost of a host-based LIMS with several corporate siblings. Laboratory test results would be printed on paper and sent to unit operations for recording and manual plotting. Laboratory statistical quality-control checks also were maintained manually, which requires additional time. The system provided basic functionalities, but nothing close to the real-time plotting capabilities the company now receives.

When the plant decided to upgrade its LIMS, it chose the PC version of Labworks from PerkinElmer Inc., Wellesley, Mass. Labworks was chosen because it is a configurable product that is designed to meet the needs of chemical plant laboratories without customization. The LIMS provides built-in tools that can be used to adapt the software to most any lab process. This made it possible to upgrade the system in just three days with minimal disruption to plant operations.

Move to automated plots

"The main reason we decided to do the upgrade was to take advantage of the online plotting program," Cook says. The Labworks Trend Plot program provides users with the ability to graphically display a series of result values for groups of selected parameters in real time. These trend plots can be used by personnel outside the laboratory for tracking manufacturing or environmental processes in a plant. They also can be used by workers in the lab for tracking instrument performance and calibration.

Cook says the software was configured to show alarm limits and specification limits in different colors on the plots, which are automatically updated every time a sample is analyzed. As a result, lab and operations personnel can see when the process units have a problem. They also can see when the units are heading toward a problem when there is still time to make corrections.

Ethyl Corp. has set up five or six plots for supervisors and process operators in each of the plant's four production units. Software automatically scans from plot to plot, making it possible to instantly review trends. The intervals between tests vary within the production units. The continuous units might receive data every six hours, whereas the blending units, which operate in batch mode, only receive data at the end of a batch.

"Our objective in implementing trend plotting was to improve our process capabilities by getting a better understanding of the variation in our process," Cook says. "Right now, we are looking closely at the variation of different parameters. If a parameter varies more than usual, even if it meets the specification, we will investigate.

Streamlined workflow

The laboratory workflow proceeds as follows: unit operations deliver the samples on a defined schedule. Each sample has a unique unit code. This unit code is defined in the LIMS with all the required test parameters and specification limits. When a sample is received, an analyst enters the unit code, date and time, and all the test parameters for the sample are quickly displayed. As a test is completed, an analyst enters the result. When all the tests are completed, the analyst validates the results. As results are saved, the value also is displayed on the trend plots.

 

The red fields indicate out-of-spec results. A left-click on any of the results will show more details, such as specs, comments or a history of results.

A wide window

Cook says the Labworks Process Scheduler provides a window into the status of every sample in the laboratory. "If we have a sample that's a high priority and want to know the status, we simply click on it and can see at a glance exactly where it is at," he says.

Lab personnel at Ethyl Corp. can use the Process Scheduler to generate a list of samples that are either waiting for analysis or for validation. Process unit personnel also have access to the Process Scheduler where they can view only their department's samples. This reduces the number of phone calls back and forth to check on the status of a high-priority sample. Cook notes this information was available in the old system, but it took a lot of time, and it was not available to unit personnel.

The Process Scheduler also serves as a valuable tool for laboratory management. They can easily see the entire backlog and evaluate how it stacks up against available resources. Cook regularly uses the Statistical Quality Control module to generate various quality control and quality assurance charts.

"We embarked on this journey by selecting the most critical parameters in each of our operating units," Cook concludes. "Then we implemented trend plotting in the new version of Labworks to make sure the people responsible for these parameters knew what they were at any minute. When we got the trend plots working, it was clear to everyone that putting this kind of information at our fingertips made a significant difference in terms of gaining control over our process and continually reducing variation."

Sandra Schiller is marketing manager of Informatics for PerkinElmer Instruments, Shelton, Conn. E-mail her at sandra.schiller@perkinelmer.com.

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