According to the American Chemistry Council (ACC), Arlington, Va., the U.S. chemical industry has halved energy consumed per unit of output since 1974. However, companies see substantial further opportunities for savings.
For instance, Air Products & Chemicals, Allentown, Pa., aims to cut both energy consumption at its large air separation units (ASUs) and fuel and feedstock consumption at its hydrogen, carbon monoxide and synthesis gas (HyCO) facilities by 7% by 2015 compared to a 2007 baseline. The company is focusing particularly on ASUs and HyCO facilities because together they account for 80% of its global energy requirements.
"For some chemical plant operators, electricity and gas are still thought of as utilities. In these two major lines, however, they are treated as raw materials. For example, air is free for an ASU, so most of our variable costs involved are for electricity, which we regard as a raw material in the separation process. So essentially we have been focused on energy efficiency for our whole history. Seven percent might not sound like a lot, but it is higher than historical improvements," says Steve Pastore, director for global energy supply.
The company now is taking a four-pronged approach to enhancing energy efficiency:
- The R&D and Technology Group is focusing on long-term process design and cycle improvements as well as short-term measures to boost ASU and HyCo performance. The group has yearly dollar improvement targets.
- Air Products' whole worldwide portfolio of plants is being assessed; several older ones currently are being replaced.
- The about-100 people globally in its process plant efficiency group are exclusively concentrating on plant efficiency using, for example, lean and six sigma approaches. Best practices -- e.g., more efficient operation of a cooling tower or an on-the-fly process control alteration -- are shared.
- The company has implemented new operation service centers (OSCs) globally that bring together a lot more plants: the company has over 100 in North America alone. The OSCs are staffed with operators and plant efficiency engineers. They use state-of-the-art data tools and process metrics. The efficiency engineers look at all the data, the differences in efficiencies in similar plants, even ones geographically far apart, and ask, "Why?" Previously, notes Pastore, operators were very much consumed with what was happening at their own plants and didn't have the opportunity to see this broader picture.
"A good example of implementing a new process cycle improvement is the ASU being built for PetroChina," he says. It marks the first time that a state-owned refinery in China has outsourced its hydrogen requirements. The facility will produce over 90 million standard cubic feet per day of hydrogen and is targeted to be on stream in early 2012.
The hydrogen production plant will feature technology advancements to maximize facility energy efficiency and emission reductions. The enhanced steam methane reforming design, by partner Technip, targets minimal heat loss to the environment, which in turn decreases the quantity of natural gas required to make hydrogen.
Air Products also offers its Oxyfuel technology to help customers improve the energy efficiency of combustion processes. This saves fuel and cuts carbon dioxide emissions. Its latest use is on a CO2-capture pilot plant being commissioned at Vattenfall's site in Schwarze Pumpe, Germany (Figure 1).