The Canadian operator of the Cochin Pipeline between Canada and the U.S. has installed a workstation-based supervisory control and data acquisition (scada) system that directly links pipeline operations to the company's business accounting computer in Calgary.
Amoco Canada Petroleum Co., Calgary, developed the remote scada system based on Sparcserver computers and Sparcstation workstations from Sun Microsystems Computer Corp. and Valmet Automation's OASyS real-time data acquisition software.
The new system replaces Amoco's older, minicomputer-based system for which parts and support had become increasingly difficult to locate.
NO EXPANDABILITY
The Cochin pipeline network runs from Canada's sparsely populated west to major commerce centers in Ontario, Quebec, and the U.S.
The 1,900 mile, 12-in. line delivers up to 100,000 b/d of assorted NGLs.
The pipeline begins near Ft. Saskatchewan, Alta., and continues through Alberta and Saskatchewan in Canada and general Midwestern U.S. states before reaching Detroit, Windsor, Ont., and back up to Sarnia, Ont.
It passes through 31 pumping stations spaced at 55-60 mile intervals, and 5 delivery points in North Dakota, Iowa, Illinois, and Ohio, where propane is unloaded into "bullet" storage units.
In the past, Amoco relied on a minicomputer as a master controller that collected data from microprocessor-based remote terminal units (RTUs) at the pumping stations and delivery points.
As the technology aged, the company had problems replacing worn-out parts and supporting the network. Additionally, inability to expand the system prevented Amoco from linking it directly to its business accounting computer at corporate headquarters in Calgary.
Networking was needed for gathering information from the field and entering it into the business system automatically. This on-line process, along with an integrated data base management system, Amoco felt to be critical for maintaining permanent records required by regulatory agencies.
Amoco's staff computer systems analyst Paul Wagner says that bills of lading were handwritten at the propane-delivery points, then collected and shipped to accounting, where clerks reentered the information into the main business system.
The process was tedious, costly and inefficient, he says. To solve this problem, Amoco installed a workstation-based system that could provide networking to its business applications.
Limited support and a lack of parts were two other problems with the former system.
Sun's SunNet permitted integration of Sybase and Ingres relational data base management system (rdbms) software into the network as well as connecting remote workstations with the master (Fig. 1).
Valmet's OASyS in conjunction with the Sun systems allows Amoco to expand and reconfigure its network as the company's requirements change, according to Larry Stack, director of marketing at Valmet Automation.
LINKING REMOTE STATIONS
Located in Fort Saskatchewan, the master scada controller consists of a Sparcserver 630 linked by dedicated telephone lines in Canada and by satellite in the U.S. to 56 Sparcstation IPC workstations placed at pumping stations, delivery points, and interchanges with other pipelines.
The workstations, in turn, interface directly to several different kinds of field devices, including pressure and temperature transmitters, that feed data back to the main scada system.
Amoco says that each remote workstation along the pipeline serves as a miniscada system, monitoring and controlling devices at its particular location.
These workstations collect field data that are sent over the network to the master server computer in Fort Saskatchewan, which automatically updates the data base.
The network's distributed data base capability also enables the master controller to redefine parameters for the various field devices, then distribute the information to each workstation.
The process reduces the time it takes to create a data base for a particular remote device, says Amoco.
Amoco has installed a second Sparcserver 630 as a back-up master server system. Linked to the master controller, this workstation also serves as an engineering development tool.
FLOWING
As product flows from Fort Saskatchewan, density detectors enable the scada system to determine the specific type of product.
Pressure from the pumping stations keeps the various batches from mingling. Because pressure requirements vary for each kind of product, says Wagner, the scada system enables engineers to communicate with field devices at each pumping station if changes are needed.
As the liquids flow to their destinations, Amoco also runs a mathematical simulation of the pipeline using Ingres rdbms software housed in the back-up Sparcserver 630.
Developed for leak detection, the model incorporates pressure, temperature, flow rate, and other real-time data collected by the scada master to calculate where a specific product is moving along the pipeline.
With Ingres, the mathematical model shows how the different batches are flowing down the pipeline.
This capability is important for safe operation of the pipeline, Wagner says. The high compressibility of each transported product requires a mathematical model for accurate and timely batch tracking and leak detection.
PAPERLESS INVOICING
The Sun network provides paperless invoicing and comprehensive storage of historical production data.
Running Sybase rdbms integrated with OASyS software on a Sun IPX workstation, Amoco electronically tracks business transactions at the five Midwest U.S. propane delivery terminals.
The new scada network enables the company to collect invoicing data from the field and directly enter it into the business system without human intervention.
Whenever a truck takes a load of propane from a storage unit for delivery to customers, the on site workstation generates a bill of lading and transfers the information to the master scada over the network.
The data are then transmitted into the Sun Sparcserver 670 business system at corporate headquarters in Calgary which issues the invoice.
As the master scada collects pressure, temperature, and flow data from the workstations, it also periodically dumps the information into Sybase for storage. This on-line process enables Amoco to maintain permanent records required by regulatory agencies.
Wagner says that because the master scada system contains a data base large enough for only about 1 hr of information storage, it transfers a portion of the data base into Sybase every few minutes.
As this data base grows, the historical information is placed onto an optical disk for long-term storage.
Finally, the scada system monitors four points where the Cochin Pipeline interconnects with other lines to transfer products.
Amoco daily injects products from its main line into other systems. When products are transferred, the scada system allows the activity to be metered and the location to be carefully monitored.
SCHEDULING PLANNED
Amoco is developing improved scheduling techniques with the Sun network. Once the upgrade is completed, customers will be able to call and immediately receive updated information about their orders.
Currently, a customer can contact scheduling personnel in Calgary to place an order, find out approximately when his inventory will be available at a propane terminal, or check to see how much product is already in-stock at a particular location.
In the future, the Sun network will also allow tracking of different product orders more precisely as they move through the pipeline and instantaneously provide customers with up-to-date reports on when their specific delivery will arrive.
As a result the locations of specific individual orders in the pipeline will be known at all times.
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