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Heat matters

Increasing legislation to reduce energy consumption and associated carbon dioxide emissions, coupled with dramatically rising energy costs, is proving a strong incentive for companies to make investments in heat recovery.

DATE 2008-11-10 AUTHOR Elaine Mcclarence

In Europe and the United States , new emissions trading schemes are calling industries to account for the carbon dioxide they release into the atmosphere by putting a price tag on every kilogram. Ian Moore, advisory consultant at AspenTech in Britain, whose job is to help industries reduce their emissions, points out, “European governments have begun to realize that if companies simply buy CO2 credits from other countries in order to meet their emissions commitments, it does nothing to help the country improve its energy performance and meet its own Kyoto commitments. So in the future, we can expect higher penalties for companies and industries that do not improve their own energy efficiency.

“The high price of oil means that the cost of all fuels is high,” Moore continues, “and hence there is a big incentive to reduce one of the major contributors to operating costs.

In Europe, CO2 emissions reduction is another significant incentive. Most CO2 emissions relate directly to the combustion of fuel, so if you save energy you save CO2 emissions, which means you have to buy fewer CO2 credits or have more available to sell.”

With the associated costs of CO2 emissions adding up to an additional 25 percent on top of the costs of the fuel, saving energy is simply common sense. Environmental performance is also improving, demanded by shareholders who see it as good governance. To be labelled a non-environmental company is to risk affecting business and that all-important bottom line.

Most energy-intensive process industries, such as pulp and paper, oil and gas production, chemicals and energy generation, already use heat recovery systems within their production. But despite their achievements thus far, more can be done. Thore Berntsson, professor at Chalmers Technical University in Sweden and a leading expert in heat recovery, believes that through process integration companies could reduce their energy use by 20 to 30 percent with a more rational and systematic approach to their energy management.

“Until now, in spite of these opportunities, measures have not been applied because energy has not been seen as a core part of the business,” explains Berntsson. Moore adds, “For a large chemical site or oil refinery, the annual energy bill could easily be in excess of 100 million euros. A 10 percent energy saving through capital improvement projects [included in the energy management] with a payback of less than three years is a conservative estimate of potential savings.”

A key report from the International Energy Agency, “Energy Technology Perspectives – scenarios and strategies to 2050,” states: “Improving energy efficiency is often the cheapest, fastest and most environmentally friendly way to meet the world’s energy needs. Improved energy efficiency also reduces the need for investing in energy supply. Many energy-efficiency measures are already economical, and they will pay for themselves over their lifetime through reduced energy costs.” Such measures can be as simple as a change to more energy-efficient light bulbs or better environmental controls within a building that adapt to outside conditions.

Berntsson points out that the risks associated with major investments in heat recovery systems are reduced as energy costs rise. He says improving heat recovery is always a trade-off between operating costs and capital costs. The “correct” balance depends upon relative energy and capital historically had very high energy costs but low equipment-fabrication costs, so it has always made good business sense to be energy efficient. In the Middle East, however, energy has at times almost been considered a free resource, so energy performance has been less of an issue. This is changing.

“With rising energy costs, many industries that previously haven’t worried too much about energy consumption are now finding there is significant incentive to do so,” says Moore. Some industries are more conservative than others, and some have less experience in heat recovery. “The oil refining industry generally understands the concept of heat recovery well and has very complex heat recovery systems,” he explains. “At the same time it can be very wary of new technologies, and there is the tendency to use shell-and-tube heat exchangers as the default, without considering alternative, more energy-efficient technologies.”

In the pulp and paper industry, which is the fourth largest industrial consumer of energy worldwide, the ambition is to become a net supplier of energy and an important player in removing CO2 emissions. It already produces half its own energy needs through biomass, but only European plants have made significant investments in heat recovery, so there are clear opportunities for further savings in this area.

“The traditional rules on saving energy no longer apply,” says Berntsson. Instead, he says, across all process industries a more systematic approach to energy management will support decision-making and investment in heat recovery.

In addition, analysis tools that help identify and optimize heat recovery are now well established and, he says, “it’s not wise not to use them.”

Pinch analysis is an im portant technique in helping to identify where energy consumption within an industrial production process can be minimized. The optimal choice as to what heat recovery matches a company’s needs is not trivial. “In any chemical process, we have a number of different streams that we need to heat up, and a number of streams that we have to cool down, ”Moore explains. “Our aim is to maximize heat recovery from heat sources in order to save energy and to make the supporting utility systems smaller.”

It’s about how you organize the energy flow, Berntsson adds. “A process industry such as a pulp mill or a steelworks often has 30 or 40 streams, energy flows of different types,” he says. “Having a method of dealing with the complexity and interaction of these energy flows is the key to saving energy.”

Wide-ranging solution

Alfa Laval provides solutions for heat recovery in many different industries – for example, pulp and paper, petrochemicals, refineries, HVAC, wastewater treatment, food and pharmaceuticals.

For solutions to energy-intensive industries such as petrochemicals, refineries and pulp and paper, Alfa Laval has teamed up with a leading process software and consultancy firm, AspenTech, to offer solutions that add up to real economic and ecological benefits. AspenTech supplies its expertise in pinch analysis while Alfa Laval provides products and installation designs that turn theory into practice.

For example, for one European ethylene plant, the companies identified a number of opportunities to improve savings. The solution they suggested would garner annual savings of around 2.2 million euros, with the additional benefit of generating CO2 credits worth EUR 569,000 a year and a payback time of under a year. For a petrochemical refinery, similar studies showed that savings of up to EUR 5 million annually could be made with a payback period of two years through the adoption of an Alfa Laval Compabloc system.

Such technology offers 95 percent heat recovery, which is 30 percent more efficient than competing systems. For an average refinery this means that emissions can be cut by 30,000 tonnes a year.

Alfa Laval is also well positioned with heat exchangers developed to transfer high heat loads from industries out into district heating networks. Surplus heat generated by an industry is normally dispersed into the air or a nearby river or sea, but with a nearby district heating network it can be used to provide heat to a community.

“This is a good opportunity to recover heat and also to reduce overall CO2 emissions,” says Göran Hedbys, general manager OEM and Comfort & Refrigeration at Alfa Laval. “However, the distance between the energy source and the users is critical, as this requires investments in pipes and pumps. But as energy prices increase, the payback calculation gets more attractive.”