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"There is nothing more powerful than an idea whose time has come," says Victor Hugo, the 19th-century French writer and author of Les Miserables. Fine, but it's also important not to get run over by the bandwagon you're trying to jump onto.So while sustainability and green manufacturing are wonderfully positive forces, the question for many process engineers is how to do it in their own applications and facilities? Sure, users can make gains by finally installing more efficient motors and drives. But then what? How much of your application will have to be redesigned to use more sustainable raw materials and produce products that are greener to use?
Well, so many thousands of different users, process engineers, system integrators and suppliers are getting into the green manufacturing and sustainability act that there are bound to be many useful ideas that you can use to do it too.
For instance, Sinopec Shanghai Petrochemical Co. recently implemented Honeywell Process Solutions' Advanced Energy Solutions software to improve controls and electricity generation, while reducing coal consumption, greenhouse gas emissions and costs at its Shanghai power plant. The plant improved the efficiency of its circulating fluidized bed (CFB) combustion process, which uses crushed coal mixed with limestone that's heated up to 900 °C, to generate low-cost electricity with low emissions. Honeywell's tools helped increase process efficiency by developing a closed-loop, advanced control strategy to optimize combustion performance for the CFB boilers while following environmental regulations.
"Our control issues at the Sinopec power plant couldn't be solved by traditional PID control loops, so we looked for a new way to improve boiler efficiency and cut emissions at the same time," says Zhao Weijie, Sinopec's chief engineer. "As the first company in the world to apply advanced control application technology to CFB units, Sinopec enhanced the effectiveness and control performance of the DCS at the CFB boiler level and for the entire plant. Even more impressive, all improvements were achieved by implementing software rather than executing a major hardware refurbishment. We also saved an estimated $1 million on the supply of energy to our refinery."
Sinopec also reports that using Honeywell's software enabled its Shanghai power plant to increase boiler efficiency by 0.48% and operating steam temperature by 2.8 °C; improve stability of combustion process variables; reduce air pollutant emissions from fuel and limestone consumption to comply with environmental standards; optimize production capacity use and transient states control; extend production asset life; reduce maintenance; and reduce expected consumption of coal by more than 500 tons and coke by 1700 tons annually.
Not surprisingly, upgrading core process controls can improve meat-and-potatoes efficiency. However, they can also help redirect procurement, resource use, operations, products and maintenance to further reduce carbon emissions, shrink environmental footprints and provide a good example for suppliers, staff, customers and the overall community.
For example, Tata Steel's plant in Port Talbot, Wales, U.K., recently upgraded the controls on its largest steam boiler with energy-management technologies and services from Emerson Process Management. However, unlike most boiler upgrades, these new controls are enabling Tata to increase its energy efficiency, maximize use of waste fuels, cut emissions and reduce its former reliance on purchased fuels.The Port Talbot facility is Britain's largest integrated steel mill. It produces more than 4.5 million tons per year of high-quality sheet steel for the automotive, construction and household appliance markets. It includes two blast furnaces and a basic oxygen furnace, as well as continuous casters and a strip rolling mill. So far, Emerson has upgraded controls on three of the site's seven steam boilers (Figure 1).
"The boiler upgrades are helping us make better use of ‘indigenous' waste fuels, such as blast furnace gas, BOS gas and coke-oven gas, which are byproducts of our manufacturing process," says Andrew Rees, manager of Tata Steel's upgrade project. "The improved controls are part of a comprehensive energy management project that's expected to reduce powerhouse energy consumption by 3% to 5% and help us achieve our vision of becoming energy self-sufficient."
To begin the Port Talbot upgrade, Emerson conducted a study to identify opportunities for improving powerhouse operations, and then designed and delivered the most appropriate integrated combustion-control, burner-management and energy-management solution. It included Emerson's SmartProcess Energy and SmartProcess Boiler optimization technologies, DeltaV digital automation system with model-predictive control, DeltaV SIS process safety system, Rosemount and Micro Motion measurement instruments, Fisher control valves, and Bettis and Hytork valve actuators.
In the past, the plant's boilers needed frequent attention, and had to use supplemental natural gas to compensate for varying energy content of waste fuels. Following the upgrade, operational stability was increased, and energy costs declined because more efficient use of waste fuels reduced the need for natural gas. Using more waste fuel to power the boilers instead of burning it in flares also helps reduce emissions.