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Korean ethylene plant reaps benefits from APC

06.01.2011  |  Hill, D.,  ARC Adivsory Group, Dedham, Massachusetts

Keywords: [olefins] [ethylene] [process control] [advanced process control] [AspenTech] [energy] [Korea] [LGChem] [propylene]

LG Chem is Korea’s first and largest vertically integrated chemical company. Founded in 1947, the company has emerged as one of the world’s top 30 chemical makers. LG Chem produces a variety of chemical products ranging from petrochemicals to specialty chemicals, as well as electronic materials.

Last year, ARC interviewed Mr. Chang-Hoon Kang, project manager at the Petrochemicals Division’s Daesan ethylene plant. Mr. Kang told us that, previously, the plant had problems meeting corporate goals due to a variety of issues such as variability of feedstock quality. However, using an advanced process control-based (APC) solution, the engineering team solved the problem to achieve plant operational stability, increase production, and decrease energy consumption. In doing so, the benefits more than paid for the investment.

Plant operations needed stability.

LG Chem’s Daesan ethylene plant is an important asset in LG Chem’s Petrochemicals unit. The plant was experiencing difficulty in meeting its corporate operations goals due to a variety of issues. The naphtha feed typically varies considerably in quality, and the plant has issues related to furnace decoking, and tank and dryer swings. Since ethylene crackers are major energy-consuming units, the dynamics of the process further prohibited any attempts at comprehensive energy management. This all contributed to a process that was seldom in steady state.

Through a quality improvement program called “gaisen,” the company had previously improved the process, more than doubling the capacity from 350,000 tpy to the current world-class capacity of 760,000 tpy. The underlying problems, however, continued to cause plant upsets, resulting in total productivity well below corporate expectations.

To have a chance at meeting corporate goals, the company realized that it must stabilize operations before it could concentrate on maximizing plant throughput, which is why the company invested to increase the plant’s capacity in the first place. Another LG Chem objective was to minimize energy consumption to produce ethylene.

LG Chem realized there was only so much improvement that could achieved with process and procedure changes. The company had some success at its Yosu plant using multivariable control, and the plant manager at Daesan was keen on trying to adopt this approach. LG Chem chose to work with AspenTech. Together, the two companies decided that the plant needed to go further than just applying multivariable control to the 11 ethylene cracker furnaces. The solution needed to be integrated with the ethylene and propylene recovery areas downstream of the furnaces. Due to the plantwide scope, inherent feedstock variations and other disturbances, they decided to incorporate the Composite Linear Program (CLP) tools with Aspen DMCplus. LG Chem’s LGSim ethylene furnace model was used to create an online model for composition and severity for the CLP and multivariable controllers.

Since this was the plant’s first experience at such a comprehensive change in automation, it had to be established through proper leadership to help people understand the coming changes. For example, the changes in the way the operators managed the process required quick adoption of new methods. Getting the employees, from operators to engineers, to work together as a team was an important challenge to overcome early on.

This was to be an integrated approach to automation; so they had to establish effective connectivity between the existing distributed control systems (DCSs) and the new APC and optimization solution. In addition, since success relied on accurate and highly available instrumentation, they had to incorporate strategies to deal with any instrument failures quickly.

Lessons learned and overall benefits.

LG Chem learned that it was possible to do such a large scope project in a short period (eight months) and within budget. This was possible partly due to the team had secured senior management’s backing early in the project scope and partly because the project team included three members from the supplier and three LG Chem employees. Including LG Chem personnel on the team continues to help, as these team members can make the necessary minor adjustments themselves over the course of the year. If a big issue arises, then they can organize a task force quickly and, if necessary, call in AspenTech under their annual maintenance agreement.

LG Chem is very satisfied with the stable operation provided by the advanced automation. The APC has a 90% service factor and drives the unit operations to the appropriate constraints. Management and operating personnel alike are now armed with key performance indicators and other performance information to help everyone stay on the productivity path.

LG Chem’s eight-month effort and $400,000 expenditure resulted in a 2% increase in ethylene and propylene production. The stabilization of the plant reduced total energy consumption by 1.5%. Combined, this represents the equivalent of about $4 million
in annual benefits. HP

The author

Dick Hill is vice president of ARC Advisory Group, Dedham, Massachusetts, responsible for developing the strategic direction for ARC products, services and geographical expansion. He is responsible for covering advanced software business worldwide. In addition, he provides leadership for support of ARC's automation team and clients. Mr. Hill has over 30 years of experience in manufacturing and automation. He has broad international experience with The Foxboro Company. Prior to Foxboro, Mr. Hill was a senior process control engineer with BP Oil, developing and implementing advanced process control applications. Prior to joining ARC, he was the US general manager of Walsh Automation, a major engineering consulting firm and supplier of CIM solutions to the pulp and paper, petrochemicals, pharmaceutical, and other process and manufacturing industries. He is a graduate from Lowell Technological Institute with a BS degree in chemical engineering. 

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