Energy Saving Diagnostics over the Lifecycle of a Plant (Thailand)

Yokogawa participated in the planning of “Survey on energy saving by IT” which was launched in 2009 by the Ministry of Economy, Trade & Industry (METI) and the Green IT Promotion Council (GIPC). Yokogawa then performed energy saving diagnostics at two of its customers' plants in Thailand.

From October 2009 to January 2010, Yokogawa performed diagnostics for energy saving at the plants of two customers who use the Yokogawa control systems. The diagnostics were done as part of the “Survey on energy saving by IT”, started by the METI and GIPC. InsightSuiteAE, Yokogawa's equipment diagnostic system, was used as a tool to collect and analyze process data, and to perform a high-precision simulation of the energy-saving effects using multivariate analysis technology. This enables one to predict the effects of energy savings, and to actualize them without modifying the existing system.

Rayong Olefins Co., Ltd. (ROC) is the second largest petrochemical company in Thailand, producing 1.2 million tons of olefin products annually in Rayong, Thailand. The diagnostics revealed that the following energy savings were possible per year, for every single unit of heat exchanger and 13 units of ethylene cracking furnaces.

• Electricity: 807,000 kWh (450 tons- CO₂)
• Steam: 1,700 tons (270 tons- CO₂)
• Fuel: 300 tons (800 tons- CO₂)

Energy saving diagnostics were performed against heat exchangers and ethylene cracking furnaces, two of the most energy-consuming equipments.

Heat exchangers tend to lose their heat transfer efficiency with operations due to fouling inside the shell and the tubes causing an increase in energy consumption. As a result, cleaning of the shell and inside the tubes in regular maintenance is necessary. ROC has several hundred units of heat exchangers; however, without the proper tools to measure their heat performance, they must rely on experience to determine the equipment to be cleaned. To solve this problem, InsightSuiteAE was installed to measure the fouling buildup of the heat exchangers up to date. Then, future estimated extent of each fouling buildup is calculated and an appropriate maintenance schedule was proposed to the customer.

Ethylene cracking furnaces also have several coil tubes set inside, through which ethylene raw materials (e.g., naphtha) flow and are thermally decomposed. Over time, the coke buildup inside these coil tubes lowers the furnaces' heat transfer efficiency. This increases their energy consumption, necessitating regular decoking which means removal of the coke buildup. Currently, ROC does not have the means to measure the extent of the coke buildup. Without this measurement, they must use equal amounts of steam to decarbonize in all coil tubes, regardless of the extent of the buildup for each coil tube. This means that more steam is used than necessary for the coil tubes with only small amounts of buildup. To solve this problem, InsightSuiteAE was installed to perform multivariate statistical analysis on 220,000 operational points, and the appropriate amount of steam was available for each coil tube according its measured coke buildup. For this control, Yokogawa proposed the steam supply optimization algorithm of Exapilot, its operation efficiency improvement package, to ROC.

Thai Acrylic Fibre Co., Ltd. (TAF), a member of the Aditya Birla Group of India, produces 100,000 tons of one the world’s three best quality acrylic fibers each year at their Saraburi, Thailand plant. At this plant, Yokogawa's diagnostics revealed that the current operating condition (two lines) could be improved to yield the following energy savings per year:

• Steam: 3,100 tons (490 tons- CO₂)
• Electricity: 6,400 kWh (4 tons- CO₂)  (As a side-effect of control valves’ stability)

Diagnostics were performed on the drying machine, which uses the most amount of steam in the entire plant, and on the plant's main control valves. InsightSuiteAE's diagnostic devices for the control loops and the control valves were installed to check the temperature control conditions. The results showed that the temperature controller of the drying machine is unstable, causing more steam to be consumed than necessary, and that the control valves are unsettled, causing wasting of air.

These efforts were made as part of Yokogawa's new service-based solution called "VigilantPlant Service™", announced in February 2010. With VigilantPlant Services™, Yokogawa works with its customers to detect and solve various problems and to maintain the effectiveness of the plant throughout its lifecycle.

For this occasion, Yokogawa worked in collaboration with its customers in Thailand who use Yokogawa control systems, by adding InsightSuiteAE and Exapilot on their existing system and performing energy saving diagnostics. As a result, potential opportunities for significant energy savings were identified. Based on these findings, Yokogawa and its customers will be looking into ways to improve the controllability that actualizes energy savings.

In order to continue the energy-saving efforts throughout the lifecycle of a plant, it is important to not only offer solutions, but also to educate the local users and provide long-term support. Yokogawa recognizes its responsibility as a global provider of control systems, and is committed to promoting global energy conservation, not only by offering products and solutions, but also by supporting its customers' plants with a long-term perspective.

See also:

• VigilantPlant Services™