Making steel takes a lot of energy. Start from the rawest of materials: pig iron, coke, and limestone. Then cook them for about 30 minutes in a volcano-like blast furnace. Notwithstanding the short turnaround, the process devours enough megawatts to dim a small city. The upside is all that leftover heat, perfectly suited for distributed energy (DE) and cogeneration. But what happens when a highly efficient cogeneration plant meets resistance from something as basic as a wastewater pump?

Engineers at the 95-megawatt Cokenergy electrical generating facility discovered the answer: costly shutdowns, disrupted schedules, and pollution troubles. Not exactly helpful to the operation's bottom line. But the outcome eventually brought new perspectives on the importance of pumps in production process management, systems maintenance, and energy savings. As a critical component in manufacturing, pump performance should be considered when planning DE projects—if for no other reason than their energy consumption, which can run higher than 20% of a facility's total electricity usage in some industries.

Pumps are so common in industry that the US Department of Energy (DOE) has devoted programs to improving their efficiency. DOE advocates a new generation of "intelligent" pumps that rely on sensors and microprocessors. Just the energy savings alone make a compelling argument for an upgrade. How does $30,000 a year on a 200-horsepower pump sound? Add in quick paybacks (months, not years), reliability plus maintenance savings, and it's easy to see why Cokenergy took advantage of the technology.

Cokenergy is owned by Primary Energy Corporation and located at Ispat Inland's Indiana Harbor Works on the shores of East Chicago, IN. It's a steam turbine generator facility, which provides electricity and process steam to Ispat's steel-making operation. Sixteen heat-recovery boilers produce steam from waste heat given off by the adjacent metallurgical coke-making facility.

Cogeneration supplies 25% of Ispat's electricity and 85% of the plant's process steam. Clean water is critical for making steam, but Cokenergy's ability to deliver it was hampered by an outdated wastewater system, which relied on a single, undersized pipe to transport wastewater and other liquids.

The result? Crippling wastewater spills—and plenty of them, due to the high particulate matter in the water drawn from Lake Michigan. Because the pumps were constant-speed centrifugal types feeding into the single pipeline, backpressure caused cavitation and breakdowns. Overflowing tanks and environmental problems made the situation all the worse.

For Cokenergy, the solution was a "PumpSmart" system from ITT Goulds Pumps. Based on variable-speed drive (VSD) technology, the systems use sensors to adjust the pump speed and flow rate, and have built-in protection against a pump's unkindest enemies: dry run and cavitation. Moreover, VSD technology makes it easier to tie into existing pipelines because their sensors can prevent overflow.

According to Mike Pemberton, marketing manager for PumpSmart Control Solutions, VSD control systems with embedded intelligence offer more than protection against system breakdowns—they save energy. "Let's say you have a pump that can run at 1,000 rpm [revolutions per minute]. If you slow it down to about 900 rpm the power consumption drops at a cubed rate," explains Pemberton. "So if a pump is slowed down 10%, the energy consumption at that load may drop 30% to 40%."

Such savings haven't gone unnoticed by pump-intensive industries, such as paper manufacturing. Nor by DOE. In fact, in 1998 the agency identified centrifugal pumps as the single largest energy consumers in pulp and paper mills. When ITT Goulds upgraded a pump system at Augusta Newsprint, DOE's Office of Industrial Technology sponsored an event to showcase the energy-saving technology.

Augusta had a compelling story. All told, the plant's use of more than 150 pump systems accounted for a staggering 21% of total power usage. For the showcase, ITT Goulds provided a typical example of pump intelligence benefits with its upgrade of Augusta's storage tower pump system.

The system was originally designed with a throttling flow control valve to manage flow from a 200-horsepower fixed-speed pump. The valve put the pump under constant strain due to backpressure and cavitation. Not surprisingly, excess energy usage and costly maintenance nagged the system.

ITT Goulds retrofitted the pump with a variable-frequency drive (in which frequency determines motor speed) incorporating intelligent flow control. The motors running speed dropped from 1,150 rpm to an average of 450 rpm. Aside from the benefits to the pump, the system eliminated the need for a control valve and its cost of maintenance. Augusta calculated a total savings of $720,000 over the pump's 20-year life cycle. Estimated energy savings amounted to $30,000 per year. Along with three additional pump upgrades, Augusta projected its energy reduction at more than 5,200 megawatt-hours per year.

The savings fall in line with DOE's Motor Market Assessment Report. It says that replacing throttling valves with VSD lowers the system's total energy use and can result in savings ranging from 5%–50%.

Why would plant designers create such inefficient systems in the first place? Augusta's situation is typical. The design was based upon a prevailing philosophy of the times: "Too much is better than not enough."

During the era of low-cost energy, designers specified oversized pumps to ensure throughput during peak production periods or to accommodate future capacity growth. In this new era of studies to track high-energy consumption, throttling down oversized pumps with flow control valves is commonly identified as an energy waster.

PumpSmart Control Solutions made five studies of Georgia Pacific paper plants, and the typical assessment results show substantial savings from low upgrade investments. For example, at one plant the total installation cost to upgrade nine pumps was $532,000. Total savings for three years was $1,022,000. The mean payback period took just 13 months.

New plants can save much more, says Pemberton. "It depends on the plant and a lot of factors, but at a minimum, 60% of pumps could run in variable speed," he notes. "We've done studies and at 60% it would cost less in capital and have a smaller footprint. It's what I call de-materializing the plant, taking the valves out of the pipes and sizing the pumps properly. It means using smaller motors, smaller pumps, and less models, which reduces inventory for spare parts. You can also eliminate bypass valves, and all of their piping."

Another plus for industrial plants is the relief from manual control. "Their problems are usually blamed on the operator," says Pemberton. "But it's impossible to get the valve and pump to run without problems because it wasn't properly designed."

It's no surprise that the blame game disappears with pump intelligence. Yet there's an additional benefit beyond running the motor at its optimum efficiency point: These next-generation pumps now collect data. In many cases, pumps reside on the manufacturing floor, and are ideally located to access data from the production process. Also, data from the pump's performance can be used for predictive maintenance.

The new approach runs counter to traditional methods of pump maintenance, which centered on scheduled preventative programs. In the past, repairs and replacements were made whether needed or not, and technicians often relied on experience and intuition for their decisions. Intelligent pumps let technicians monitor conditions in real time. Information on wear, stress, and operation status allow for repairs on a need-to-be-made basis. "We have software that can tell where the pump is wearing out," says Pemberton, "such as the impeller. You can see declining performance and set a schedule to coincide with the plant's outage instead of having an emergency which could shut the plant down."

Aside from lower energy, capital, and maintenance costs, intelligent pumps offer a tangible benefit to the environment: reduced pollution. Pemberton says the largest leak paths at refineries and most chemical plants are the valves and pumps. Variable-speed controls remove the valve and run the pump at a slower speed, thus reducing internal stress on the pump and leakage.

With all the benefits intelligent pump systems offer, the technology is far from a slam-dunk in terms of commercial acceptance. It's certainly not a question of market size, however. The ARC Advisory Group, a manufacturing and logistics consultancy, expects the worldwide market to grow to $184 million by 2006. Outside of the United States, the European Union (EU) is advocating the use of energy-saving pumps. EU's motor challenge program estimates that industry could save 10 billion euro a year by using more energy-efficient motors. Carbon dioxide emission would also fall by 100 million tons, equivalent to one-quarter of EU's Kyoto commitment. So why aren't manufacturers rushing to make the intelligent choice?

The ARC group cites culture change among engineers as one problem. From Pemberton's perspective, it's a lack of concern for demand reduction in energy and production management systems, and plugging that leak in the bottom line.

"Managers look at their budgets and the areas where they need to optimize, such as pumps," says Pemberton, "but next year the upgrades get lumped in with all capital projects and usually fall to the bottom of the priorities. Upgrading may have a great payback, but it's a relatively small one-time shot compared to a bigger capital project worth a million dollars. So there needs to be a management system that recognizes the priority of optimizing pumps and getting long-term improvements."

Despite the resistance, Pemberton predicts continued growth. He notes that in many mature industries such as paper, lower manufacturing costs are the only method of raising profits. And for new industries such as distributed energy producer Cokenergy, intelligent pumps offer higher reliability, lower maintenance, and less of a drain on the generated power before it gets to the end user.

ED RITCHIE is a writer specializing in energy, transportation, and communication technologies.

DE - September/October 2004