By Adrian Howell, Process Control Manager, SECCO SECCO
, a joint venture between BP, Sinopec and Shanghai Petrochemical Corp. (SPC), recently opened its huge, new petrochemical facility at the Shanghai Chemical Industrial Park in Shanghai Province, China, about 31 miles southwest of Shanghai. The $2.7-billion ethylene cracker complex (See Figure 1 below)
comprises 10 separate plants, with a main ethylene cracker capable of generating 900,000 metric tons per year (MTY) of feedstock. The other plants rely on this feedstock to produce polyethylene, polypropylene, styrene, polystyrene, acrylonitrile, aromatics and butadiene.
Each of the complex’s 10 plants is the largest of its kind in the world, enabling the overall facility to produce about 2.3 million metric tons of chemical products annually.
Rather than hiring a general contractor to oversee the project, SECCO decided to use an integrated project management team approach, in which each plant in the complex had a lead project contractor. A main instrument vendor (MIV) was selected to not only engineer and implement the automation and control systems, but also to help manage multiple international and local suppliers for each of the 10 plants. The alternative to working with one MIV would have been to work directly with many different instrument companies, which would have reduced construction efficiency and consumed much more time.
|FIGURE 1: CHINA SYNDROME|
The SECCO complex near Shanghai in China comprises 10 separate plants, with a main ethylene cracker capable of generating 900,000 metric tons per year of feedstock.
also selected Foundation Fieldbus communications as a central feature of the facility’s automation approach. Foundation Fieldbus not only simplified the construction and commissioning phase, but plant officials also expect it to reduce maintenance costs by as much as one third.
Fieldbus technology also allows the complex to use truly distributed control. For example, many of the plants’ basic process control functions operate within the field devices themselves (See Figure 2 below)
, rather than in the main automation system.
The complex is the largest Foundation Fieldbus installation in the world. More than 10,000 of the plant’s 20,000 devices are networked with fieldbus technology to deliver digital process, control, and device diagnostics information. Overall, the complex includes more than 48,000 loops, with about 166,000 I/O tags. Approximately 25,000 points are hardwired to the automation system. There are more than 70,000 cables in the facility.Accelerated Schedule, Completion
The project’s main challenge was its aggressive schedule: to go from bare ground to a fully functional facility in two and a half years. As plans were developed, one major goal was to have the plant operational by July 2005. At the time, that target date seemed impossible. However, construction of some facilities started in early 2003, the bulk of the work was finished before the end of 2004, and the plant went online in March 2005, in what was considered to be a phenomenal success.
To ensure a smooth launch, the complex’s downstream plants were started prior to the ethylene cracker, relying on imported feedstock to ensure everything was working properly. The plants did very well. In particular, the polypropylene unit came online very smoothly. The unit even ran out of feed, and it was necessary to shut the plant down to wait for our own olefins unit to come online. Mechanical completion for all 10 plants was completed on Dec. 28, 2004. The downstream plants went online in February 2005, and the ethylene startup was March 18, 2005, which was more than four months ahead of schedule.
In addition, the ethylene cracker was running on-spec in just 10 hours and 45 minutes. Considering the complexity of building 10 units at one time, and expecting all of them to start up in a short time frame, the timing achieved is amazing. Moreover, it was done with minimum disruption, very quickly, and achieved high levels of performance almost immediately.MIV Method
Previously, SECCO decided that using an MIV approach would be best for the project. The MIV would work with SECCO to implement the automation and control systems, and help manage multiple international and local engineer-procure-construct (EPC) suppliers for each of the 10 plants.
After evaluating several suppliers, SECCO selected Emerson Process Management
for its breadth of digital automation, including field instrumentation and systems, and for its experience in managing large-scale projects. Emerson had excellent resources in China, and could call on its global resources, specifically from its engineering centers in India and Singapore, to supplement its local resources.
Emerson and SECCO created framework agreements for all EPC contractors to use, enabling consistency across the site for current and future operations. This was vital to achieving SECCO’s long-term goals of ease-of-use and reduced maintenance by making sure that every process in the 10 plants was developed consistently.
|FIGURE 2: FIELDBUS CONTROLS|
|All single-loop PID control functions are accomplished in local fieldbus devices.|
As MIV, Emerson developed functional design specifications, and communicated and enforced conformance and standardization by every vendor throughout the facility, which was a vital step in maintaining operating efficiency in the tightly integrated complex. Emerson actually provided separate teams for each of the 10 plants, rather than having one team move from one plant to the next. Emerson also appointed a program director and an engineering and quality manager to oversee the plants.