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.
Several years ago, ARC Advisory Group 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, they more than paid for their investment.
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 consume a large quantity of energy, 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.
To have a chance at meeting the corporate goals, the company realized it must stabilize plant 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 the energy used to produce ethylene.
LG Chem realized there was only so much improvement it could achieve 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 at his plant. 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 eleven ethylene cracker furnaces. The solution needed to integrate with the ethylene and propylene recovery areas downstream of the furnaces. Due to the plantwide scope and the inherent feedstock variations and other disturbances, they decided to incorporate the CLP (Composite Linear Program) tools with Aspen DMCplus. LG Chem’s LGSim ethylene furnace model was used to create of an on-line 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 establish the 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 the new methods. Getting the people, from operators to engineers, to work together as a team was an important challenge to overcome early.
Lessons Learned
LG Chem learned that it was possible to do such a large scope project in a relatively short period of time (eight months) and within budget. This was partly because the team had secured senior management’s backing early in the project scope and partly because the project team included three people from the supplier and three LG Chem people. The APC has a 90 percent service factor and drives the unit operations to the appropriate constraints.
LG Chem’s eight-month effort and $400,000 expenditure resulted in a 2 percent increase in ethylene and propylene production. The stabilization of the plant reduced overall energy consumption by 1.5 percent. Combined, this represents the equivalent of about $4 million in annual benefits.
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Dick Hill, [email protected], is Vice President, ARC Advisory Group, Dedham, Mass.
