Fenceline-monitoring system solves big problem

The new fenceline-monitoring system at Tosco Refining Co.'s Rodeo, Calif., refinery monitors the north and south perimeters of the refinery for 38 chemicals.

The Tosco Refining Co. Rodeo, Calif., refinery installed a fenceline-monitoring system in 1997.

According to Dale Iverson, senior environmental engineer, it is the first of its kind in the world. The system identifies and measures the quantity of defined gases, such as methane and benzene, along the perimeter of the refinery.

While the introduction of new technology into refineries can be a slow endeavor, unexpected events can push the process along more rapidly.

Such an event occurred at the Tosco Rodeo refinery (formerly the Unocal San Francisco refinery) in 1994. On Labor Day of that year, the Rodeo California refinery experienced a major release of catacarb, a CO₂ absorber used to purify hydrogen.

As a result of that release, permits for new construction and land use were delayed by local authorities under pressure from community and local environmental groups. The permits were held up for 6 months while the parties negotiated additional equirements. Among the myriad conditions the refinery had to meet was the implementation of an improved fenceline-monitoring system.

The related public relations and political skills needed to manage this problem proved to be as challenging as the technical effort.

The program

Tosco was unable to rely on the experience of any other refinery. As far as it knew, it was the first refinery to install such a monitoring system.

First, Tosco established a fenceline-working group to find the most appropriate technology for a fenceline-monitoring system. This committee was made up of people from the community and refinery representatives.

The fenceline-working group reviewed the available technologies and came to an understanding about what each one could do to monitor the air quality around the refinery. To do this, the group collected information on different technologies from several sources and evaluated products from various equipment manufacturers.

A test program was then outlined, and additional negotiations were made. This included a 6-month test of Fourier Transform Infrared Spectroscopy (FTIR) detectors on two 200-m paths at the facilities' north and south borders.

Talks were then continued with the fenceline-working group to identify the final system.

Ultimately, Petris Technology was selected to implement an improved fenceline-monitoring system. The purpose of the system is to monitor, identify, and measure 38 chemicals.

The new system uses two FTIR remote sensors, four ultraviolet (UV) remote sensors, and four laser detectors, all located on the refinery's north and south borders. Point-source monitors inside the plant complete the system.

Implementation

After the 6-month test program was completed in 1996, the final system was installed in 1997 on a 6-month schedule set by the county. The FTIR was installed first. A big hurdle in the system was the need to tie the different technologies together.

Tosco felt that one of Petris' strengths was its ability to encourage the interaction among Petris, the vendors, construction companies, community groups, and local government to work as a team.

The Petris hardware system has a meteorological data tie-in that is able to integrate wind speed and direction.

An iterative design and construction approach helped alleviate the problems common with such a new system. This design approach also better accommodated the short time schedule that had to be met. The refinery and Petris had to move quickly and adjust as needed.

Real-time data from the monitoring systems are displayed on a computer screen designed by Petris. Data summaries are sent to local government agencies, community groups, and refinery representatives.

Fig. 1 [43,369 bytes] shows a screen snapshot of the real-time display that is seen in the control room.

Fig. 2 [190,145 bytes] is a control diagram of the new system. FTIR, UV, and TDL (tuneable diode laser) detectors are located in the northern and southern fenceline shelters on the refinery's perimeters.

The system requires a complex computer network and uses a fiber-optic backbone. In addition, the numbers for alarm levels had to be agreed on by the fenceline-working group, the refinery, and the local health department.

The system was successfully implemented on time and on budget. This allowed Tosco to meet the commitments it made to the community groups and permitting agencies.

Data handling and maintenance

Petris Technology offers data communications and management to support its air-monitoring system. The Optical Remote Sensor (ORS) technology collects and distributes real-time data immediately to client systems. Additionally, complete data sets may be transferred to a central archive for review, reporting, and long-term storage. An easy-to-use interface provides on-line access to authorized users.

All of the data resulting from the monitoring system are handled by Petris. This addresses any credibility concerns about the reports that are provided to the community and local authorities that may worry about data manipulation.

The system that was installed requires routine maintenance. The refinery handles infrastructure (e.g., electrical systems) and the rest is handled by Petris.

Petris, which has an ongoing contract with Tosco, is on-site every 2 months and has remote access that allows it to dial into the system and make necessary modifications.

It is important to remember that the system is not a "clock radio" that can be plugged-in and walked away from. In the initial implementation and planning process there were some perceptions that the system would successfully run by itself with little intervention or maintenance. However, this has not proved to be the case.

Results

Since the system has been put in place, no high alarm levels have been reached. When there are detections, they tend to fall near minimum levels. And fortunately, said Iverson, there have been few surprises.

"This is a good thing," Iverson said. "I was hopeful and pleased that it would work out this way."

Iverson has said that one of the best lessons he learned from the experience has been not to have a release. It has been estimated that around $100 million will have been spent to deal with the 1994 release. Of that cost, about $2 million was used to implement the new fenceline-monitoring system.

Although the ORS system works, it needs attention and requires a high-powered computer system back-up.

The flexibility of the facility is essential. The facility is able both to look at the entire monitoring system and to focus on specific areas of concern, such as siting, chemicals, detection levels, and technologies.

Iverson advises other refineries to be proactive in the implementation of air-monitoring technology and review the need for this type of information system before a release occurs. He says the refinery should stay technical, stay focused, and choose a system that is able to identify problems and provide useful data.

For Tosco, this meant implementing a high-tech air-monitoring system that allowed it to get the permits it needed to construct facilities that will produce cleaner burning gasoline in California.