Critical Condition Monitoring and Management

Transcription

1 Critical Condition Monitoring and Management By Lothar Lang, Lyondell Chemical Company Keywords: real-time performance, information, alarm management, control loop monitoring, condition monitoring, performance, performance supervision, manufacturing intelligence, optimization, troubleshooting, variability, diagnostic, continual improvement Abstract Critical condition management is addressing the operator s workload and ability to handle plant disturbances and abnormal conditions. The main aspects are alarm management, controller performance monitoring (CPM), operator graphics and operator advisory systems. These human reliability aspects are addressed by Lyondell's Operations and Controls Best Practice team. The focus of this presentation is on the current status, metrics and implementation of alarm management and CPM. To emphasize the nature of this continuous improvement process, Lyondell has introduced meaningful key performance indicators (KPI) and efficient support tools for alarm management and controller performance. These are currently being rolled out to all Lyondell sites. This is an important contribution to increase human reliability at Lyondell s production sites around the world. Summary What Is Critical Condition Management? Critical Condition Management is a comprehensive approach to reducing human factors contributing to abnormal situations. Lyondell s approach to critical condition management includes the following components: HCI (Human Control Interface) Alarm Management Control Loop Performance Management Operator Advisory System Company-Wide Best Practices Company-Wide KPIs

2 Lyondell Background Lyondell, a Fortune-500 company, is one of the world s 10 largest chemical companies, with operations on four continents, and nearly 8,000 employees. Lyondell is among the best in the industry for on-the-job safety. Key products include ethylene, propylene, polyethylene, propylene oxide, styrene monomer, MTBE, and acetic acid. Lyondell also owns an oil refining business. Lyondell has a focus on continuous improvement in environmental performance, product quality, and reliability measures. The critical condition management program is the latest addition to the continuous improvement efforts at Lyondell. Work Completed at Lyondell Lyondell has taken a phased approach to addressing critical condition management. The tools, training, and techniques have been proven at prototype locations and have then been rolled out company-wide. Some sites are just beginning this process, while others are well on their way. Details of the work completed are covered later in this paper. Benefits from Critical Condition Management Even in its early phases, the critical condition management program has delivered measurable results in the following areas: Program Benefit Measures (typical) HCI made ASM-Compliant Time to complete tasks Detection of failure Reduced 35%-48% Improved 38% Alarm Management Reduced alarm load Baselines established Control Loop Performance Monitoring Reduced energy costs Work in progress Similar results are expected as the program is rolled out company-wide. Reduced 15% in some units

3 Critical Condition Management The Starting Point Like many other companies in the industry, Lyondell faces some challenging problems, as follows: Operators become overwhelmed during upset conditions. HCI designs may be confusing, with too much data, colors, and graphics. Operators are less experienced than in years past. Each operator has a larger scope of control. Guiding Principles To ensure the success of the critical condition management program, Lyondell has adopted the following guiding principles: 1. Empower the front-line operators. a. Heighten their situational awareness. b. Prioritize. c. Automate key information. d. Share information to the right decision-making points. e. Engage teams in continuous improvement. 2. Drive the program intelligently. a. Develop and re-apply best practices. b. Establish uniform KPIs. c. Communicate among plants, and corporate. HCI Design Improvements Following is the Lyondell approach to HCI design: 1. Document the best practices. 2. Focus attention on the critical information. 3. Assess the situation at a glance. 4. Re-apply company-wide. The new displays were designed to be ASM-compliant. Using standard color codes and symbols, the new HCI design is shown in Figure 1.

4 FIGURE 1. New HCI Design Control Loop Performance Management The base layer of controls is often neglected in modern industrial plants. In fact, it is quite common for as many as 30 percent of control loops to be running in manual at any given time. This, of course, is the symptom of larger issues, such as the following: Broken or non-performing sensors Poor controller tuning Poor control design Mechanical control valve issues Changes in operating conditions, outside of original design ranges Lack of operator trust in the controls As shown in Figure 2, Lyondell is in a significantly better position, as measured by loops in normal mode. Only 16 percent of loops, on average, are not in their normal mode. However, as will be seen later, significant gains are still possible.

5 FIGURE 2. Lyondell Benchmark for Loops in Normal Mode Average: 81.9% Plants The control loop performance management program at Lyondell is broken into the following phases: 1. Benchmark and assessment a. Defining KPIs b. Establishing baselines 2. Analysis systematic review of worst performers a. Hardware b. Tuning c. Control structure 3. Implementation a. Capital planning b. Turnaround planning 4. Continuous improvement a. Performance monitoring and optimization b. Publishing and reviewing KPIs 5. Maintenance and sustainability After an extensive study, Lyondell selected PlantTriage from ExperTune as the basis for control loop performance monitoring. This system includes complete monitoring of

6 instruments, valves, tuning and many other factors of loop performance. A web-browser interface allows information to be shared easily across the company network. Plant and loop dashboards, as shown in Figure 3, are used to focus attention on the problem areas. FIGURE 3. Plant Dashboard (Left) and Loop Dashboard (Right) Benefits of Control Loop Performance Management While it is quite early in the process of documenting results, Lyondell has seen improvements in smoother operation, reduced operator input and reduced upset conditions. Several plants have shown specific bottom-line benefits in efficiency and energy consumption. Case Study: Energy Cost Reduction As an example of the type of benefits possible, we can examine specific energy consumption in a finishing unit. When we compare specific energy consumption at constant production rate, we see a 15 percent drop in energy requirements, over a 1-year period. Figure 4 shows specific energy consumption dropping over time.

7 Increased stability and reduced oscillation are expected to drive similar improvements in quality, production rate and efficiency. FIGURE 4. Energy Savings from Control Loop Performance Monitoring Specific Energy consumption vs feed for various time periods BTU/feed nd Q rd Q th Q st Q nd Q 2006 Poly. (3rd Q 2005) Poly. (4th Q 2005) Poly. (1st Q 2006) Poly. (2nd Q 2006) Poly. (2nd Q 2005) Feed Alarm Management Modern control systems make it easy to add alarms. In many plants, the operator may be inundated with low-value alarms. During upset conditions, a serious alarm can easily be hidden among the flood of unimportant alarms. EEUMA (Engineering Equipment and Material Users Association) guidelines call for a goal of fewer than six alarms per operator, per hour. At the end of 2006, Lyondell averaged roughly double that alarm rate. Lyondell has taken the following two-phase approach to alarm management: 1. Provide real-time reduced alarm lists to operators. 2. Prevent alarm floods by predicting process upsets. To rationalize alarms, the Lyondell critical condition management program has applied TiPs LogMate alarm management software. This tool is being used to measure current alarm rates, rationalize and prioritize, and to make improvements to the situation. Figure 5 shows how the tools can identify the most frequent alarms, helping to narrow the focus on the bad actors.

8 FIGURE 5. Most Frequent Alarms Conclusions While it is still early in the roll-out of the critical condition management program, it is clear that results will be measurable and significant. Results of early implementations and tests include the following: percent reduction in energy in a finishing unit percent improvement in failure recognition percent improvement in dealing successfully with failures, including faster recovery from process upsets Lyondell is currently accelerating plans to implement best practices and install standard tools and KPIs worldwide. Footnotes 1. ASM is a registered trademark of Honeywell, Inc. 2. LogMate is a registered trademark of TiPS, Inc. 3. PlantTriage is registered trademark of ExperTune, inc.