A good processing plant will provide a checklist of items to help an operator perform normal routines. As an energy manager, you need to make sure those checklists include information on energy efficiency. Let's go through the energy management basics that should be part of your every day routine.
Steam. Though widely used because of its versatility and ability to transfer heat, steam often suffers from poor energy management. I still know plants today with enormous amounts of steam piping and tracing that go through unused or removed portions of the plant. While a complete overhaul of an older plant's steam system isn't always feasible, a well-run steam-trap program can help cut down energy costs.
Your steam maintenance checklist should include a complete map of all your traps, test traps for leaks, and replace traps where the replacement would pay for itself in less than six months (or whatever goal you set). If trap locations seem to always need replacements, check that the system was designed properly.
The other problem with steam is when you let down pressure without recovering work. Look for let-down stations that are constantly open and see if you can use that energy for pump work or electrical production.
And finally, you need to watch your insulation or loss of heat in the system. A well-designed system never allows a large amount of heat loss. The easiest way to tell is to watch steam demand during a sudden rainstorm. If you have to increase steam production more than 20%, then your system is in deep trouble.
Electricity. Although the electric system is probably the least worrisome in terms of ongoing maintenance, it's an area that can often sees neglect. Motor and lighting efficiency are two areas that can really help reduce your electric bill. In some areas, choosing to run certain operations at night can be cheaper than running during the day. I often find that very few plants share this price tier system for electrical use with operators. With that knowledge, operators can delay movements or tasks while not affecting production goals to save on energy costs. A well-designed energy management software program can also help operators make energy choices to save money.
Fired Heaters. Whether using oil, gas or solid fuel, fired heaters can produce good energy savings. However, most operators are only trained on the basics of their systems and most plants don't question whether the heater is running efficiently.
For instance, one plant I audited had no idea its excess air numbers were extremely high. The site had an outside company maintain the heater and operators kept complaining that the heater shut down too often during startup. As it turned out, the operators were hurrying the startup time and the heater had an automatic air/fuel ratio control so when they pushed fuel, the program would only add so much air. The heater would starve for air and automatically shutdown. After numerous complaints, the maintenance company just set the ratio very high so that there was always excess air. It was better for startup, but bad for efficiency. Once the operators understood the limitations during startup and how to run the heater efficiently, fuel usage was cut by 20%. So, always make sure heater training includes heater efficiency and heater economics.
Other ongoing issues — especially with older heaters — are leaks, insulation and burner adjustments. A thermal imaging camera can help troubleshoot these problems. If you take good care of the fired heater, you should be able to maintain good efficiency throughout your plant run.
Air. Just like with steam, leaks are very common. Unlike with steam, they are harder to spot and repair. It's not unusual for plants to use 50% more air then they need; clamping down on air leaks can definitely save money. While a good sonic device may help you, this is one area where a trained DOE-qualified specialist can come in handy.
In fact, in all four of these areas — steam, electricity, fired heaters, and air — check with your vendor or with the DOE Office of Industrial Technology to get a qualified specialist to talk to your operators, walk the units and give your plant personnel direct advice. It will be well worth the time and effort.
It's not easy to maintain an energy program, but if you have the basics handled, you will be miles ahead of your competition.
Gary Faagau is Chemical Processing's Energy Columnist. You can e-mail him at GFaagau@putman.net.