Keeping Air Liquide Operations on Course

arc Hoffland compares his job to that of an airline pilot, although he never leaves the ground. The variety of complex panels and screens he constantly monitors during his 12-hour duty certainly resemble the complicated controls of a major aircraft.

But Hofflands jet is more than a piece of machinery. The Air Liquide production network duty control engineer is keeping constant watch over pipeline operations at the Command and Control Center in Houston, where 13 Air Liquide employee analysts, engineers and computer staff keep Air Liquide pipline operations on steady course.

The plane in this case is Air Liquide's Gulf Coast and Mississippi River Pipeline Systems - a complex network of more than 1,660 miles of pipeline supplying more than 43,012 tons of oxygen and nitrogen and 200 million standard cubic feet of hydrogen and carbon monoxide per day to customers.

From this sophisticated command post the Operations Control Center (OCC) employees, like Hoffland, continuoisly monitor operations 24 hours a day, seven days a week, to be on top of product delivery and operations at 500 customer locations and Air Liquide's on-site plants, cogeneration facilities and air separation plants.

"Our primary focus is both the integrity of supply to our customers and operating efficiency for Air Liquide," says Charles Harper, Director of Pipeline and Supply Operations.

To ensure operational efficiency, the center uses a telemetry system known as AL-TACS (Air Liquide - Telemtry Acquisition and Control System), known in other terms as SCADA (Supervisory Control and Data Acquisition), to observe all plant and pipeline information. The system also provides a data input and output highwayfor sophisticated computer modeling programs to determine the best way to operate the pipeline system, in real time.

The models identify three dimensions for optimization - hydraulic limitations on the pieline system, the lowest-cost energy available and most efficient equipment to run - and thereby determine peak operational configuration.

The OCC also evaluates risks to operationsposed by weather, energy supply curtailment, plant production problems, plant or pipeline maitenance, or customer demand changes.

Keith Taylor, Energy and Analysis Manager, explains how factors such as weather and electricity costs can impact daily operations. "Electricity is our primary feedstock, accounting for roughly 70% of the cost of production. We spend a total of $7-8 million for electricity per month for the two pipeline systems. Each month, I estimate our power costs for all facilities, and this information is used in the optimizer model to help us run most efficiently."

Inside the OCC, employees are continuosly monitoring system operations. Two large screens show weather and lightening activity across the nation. A bank of 14 monitors and a wall with three large screens reveal plant and customer real-time activities.
          
Every six hours the controller on duty takes information on current plant production and customer loads and feeds it into the
optimizer model for advice on
how to configure the system. The output shows recommendations for each plant's operation that reults in the most cost-effective operation of the system as a whole.
    
"If a plant has higher pressure on the pipeline, its compressors are working harder, where a plant at the other end may not have as much pressure. We use decision support tools to determine if it's more economical to ramp the plants at the low-pressure end or to maximize the troughput of the pipeline," explains Product Supply Manager Patrick Caudill.

Cudill and fellow Product Supply Manager Clarke Hayes support the minute-by-minute monitoring with forecasting of needs for the next day, week, and month. "We're looking at the entire system and coordinating with the field to make sure everyone is on the same page and supplying customers in the most efficient way possible."

While most days are fairly routine, unexpected weather conditions - like a hurricane - or swings in electrical loads can put the OCC into overdrive. Harper says risk management is a key responsibility of the group. "We gather all weather and electricity supply information that might affect the pipeline load. Last year, due extrememly hot weather in the eastern U.S., our electricity supply was affected. We had to manipulate the system to survive multiple power curtailments. A direct hit by a hurricane also requires that we reconfigure the system to satisfy out customers' needs," Harper says.

Support Staff Engineers Michael Dew, Karen Eng, Garland Lyon, Ronnie Reid and Tyler Reitmeier provide technical analysis, engineering, production and software support for the group. "Their role is critical. Without our working systems, optimization models and support tools, we never could have gotten this far," Harper says.

While the group plans on a long-term basis to be prepared for the unexpected, weather events, power outages and customer load changes can put the duty control engineers like Hoffland in the hot seat. "The plane is always flying. If I'm in the middle of a hurricane, I have to fly through it. I like to feel I am in a job where my decisions make a difference. I try to keep the plane flying in the most cost-effective way for the company," says Hoffland.

Air Liquide's
Crown Jewel

Customers and Industry visitors who frequently tour the Operations Control Center (OCC) in Houston are impressed with the NASA-like command center for monitoring pipeline operations.

What's most impressive is the fact that this system, which was developed in-house, has grown over the past eight years from two sites (Bayport, TX and Plaquemine, Louisiana) offering only local information, to 27 sites across the country that can be monitored from the OCC.

Manager Dale Shaw and Sultan Mulkhi, with the Telemetry and Project support group, have been largely responsible for growing and customizing the systemd to meet Air Liquide's needs. They've developed 1,800 different screens that supply critical operations information, including tank-level monitoring, customer product loads, plant loads and purities, plant power consumption, plant efficiencies, pipeline control, and weather system monitoring.

Not only does the OCC use the information to monitor Air Liquide facilities and customer operations along the pipline system, many other departments use the information for business analysis, including engineering, billing and trucking. The system is even used to help customers support their own operations, like the Texas Eastman facility in Longview.

While his group has created a monitoring system that is a showcase in the industry, Shaw says he most proud of the fact that they have a reputation for getting things done.

When an engineer at Air Liquide's plant in Westlake, Louisiana, wanted a computer program to calculate mass balance, which determines the balance of airflow in and out of the pipeline, Shaw's group delivered. "On the very first day we found something was wrong. The computer program revealed a product leak." Now the program has been implemented across the system.

Shaw investigates the need, and Mukhi helps develop and support new software systems, designing user-friendly screens for easy interpretation. For example, to show product availability at a plant the screen depicts product levels in tanks. Allan Madar provides hardware support, assisting with equipment installation and field communication links.

This year, the group is installing eight new SCADA systems, and plans to add an additional 40 sites over the next couple of years, including all large Tonnage and Merchant plants. "Our vision is to have all plants in the United States on the SCADA system," Shaw says.