Flue gas desulfurization is one of the technologies that have helped clear the air. A power plant burning lignite can churn out 600 to 3,500 mg of sulfur dioxide for every cubic meter of exhaust gas. But that potential contribution to acid rain and smog can be taken out of the exhaust before it reaches the atmosphere.

A desulfurization plant introduces a lime solution into the exhaust stream. The lime reacts with the SO₂ to create calcium sulfate, CaSO₄. As a result, what would have been a pollutant becomes a less harmful substance, which in many cases can be sold to manufacturers of building materials. Calcium sulfate, also known as anhydrous gypsum, is used commercially in the manufacture of cement, plasterboard, and glass.

A belt carries gypsum, derived from flue gas de- sulfurization, through vacuum drying.

The direct output of the scrubber is a slurry that is mostly water. Before it can be sold, or disposed of in any way, the water needs to be removed. Part of the dewatering treatment is to convey the solution on a belt through a vacuum drying process.

A company in Germany, a country that mines perhaps 180 million tons of lignite every year, markets process filter belts designed to carry the gypsum slurry as it dries. The company, GKD-Gebr. Kufferath AG, based in Düren, calls the belts Weave in Motion.

According to GKD, the belts are double-weave twill made of polyester monofilaments. Type 2035 has multifilament weft wires. Another version, type 2025, has staple fibers. Mesh apertures in the belts can be ordered in a range of 20 to 400 micrometers. The company claims the belts have exceptional cross-stability in widths up to seven meters and lengths of 120 meters.

Dewatered gypsum falls from the belt. Power plants frequently sell the byproduct to manufacturers of glass or building materials.

The company says that a 3,800 MW lignite-burning power plant in Niederaussem, Germany, has 11 scrubbers working. Two type 2035 belt filters have been running there since the end of 2004, carrying about 8,000 tons of slurry that are reduced to 800 tons of calcium sulfate every day.

GKD says Weave in Motion belts are used in other industrial and environmental fields, from filtration of abrasives and sewage dewatering to refinement of phosphoric acid and rock salt processing . The company, which describes itself as "an owner-managed technical weaver," also manufactures Solid Weave filtration and separation media, and Creative Weave metallic fabrics for architecture and design.

A valve manufacturer in Massachusetts is moving into a newer and larger factory to prepare for increased demand from the nuclear power industry.

The manufacturer, Weir Valves & Controls USA, in Salem, Mass., is moving its nuclear valve operations to a three-year-old plant in nearby Ipswich. According to Peter McGovern, vice president of marketing, the company has operated at the Salem site since 1917. He said the company's market research has led it to prepare for a sharp increase in orders from around the world for valves to fit nuclear power plants. The company expects to begin operations in the new facility this fall.

The new site has 106,000 square feet and is expected to permit the company to develop a better work flow than it has at Salem, McGovern said.

Weir Valves & Controls is also preparing for qualification testing required to demonstrate that its products can function properly for the 60-year design life of the next generation of nuclear power plants. Qualification testing for the new nuclear power is expected to include ASME QME 1, which quantifies valve performance. Testing will include seismic evaluation, wear, effects of tolerance, environmental effects, and aging. The company's vice president of engineering, Sam Shields, is a member of the ASME QME 1 committee.

McGovern, an ASME member, said that the company decided to purchase the site partly because the plant already had heavy-lifting equipment in place. Valves for nuclear plants can weigh as much as 60,000 pounds. The Ipswich plant has a 40-ton crane in its shipping area.

Weir Valves & Controls is phasing out the Salem site. The company makes commercial valves and has moved those operations to North Carolina. It also operates a plant in China to make valves for the Chinese market. The company plans to keep only its nuclear business in Massachusetts, McGovern said.

With the move of the nuclear portion of its business, the company is in talks to sell the Salem property. Staff at Salem will transfer to Ipswich, about 12 miles farther north on the state's North Shore.

Weir Valves & Controls used to be known as Atwood & Morrill Co. It was bought in 1990 by the Weir Group, which changed the name in 2000.

Sometimes an unexpected outcome of a project can have far-flung implications. When a Dutch manufacturer set out to develop a new air-cooled cooler and fan that ran quieter, the company's engineers were surprised by the improvement they got. The company, Bronswerk Heat Transfer BV in Nijkerk, says that it achieved unexpected gains in efficiency, as much as 20 percentage points better than the performance of older systems.

Since its inception in 1940, Brons- werk has become a leading designer and manufacturer of heat exchangers, compressors, and fans. Its customers include Shell, Exxon Mobil, Bayer, Philips, Unocal, and Texaco.

An air-cooled cooler and fan system as they appear in a typical customer installation.

Bronswerk's air-cooled coolers are used as process coolers in handling oil, gas, and chemicals. Fans range from 2 to 10 meters in diameter and cool heat exchangers that are also extremely large—often as big as a building. While designing a new generation of industrial cooler systems and fans, engineers at Bronswerk faced a difficult challenge: to develop a new cooler and fan and make them as quiet as possible to meet stringent standards set by government agencies around the world to protect health, safety, and cleanliness of the environment. The fan would have to cope with a wide range of environmental fluids and pressure conditions from wind gusts and other sources.

The engineering team at Bronswerk used a combination of Pro/Engineer Wildfire from PTC for creating the design and EFD.Pro from Flomerics for flow and thermal analysis. Since EFD.Pro is fully embedded inside Wildfire, the combination of the two engineering tools let Bronswerk use a single platform for design and analysis. Flomerics acquired the EFD software when it purchased the German-based developer Nika last year.

Airflow analysis of the system offered additional insight to the Bronswerk engineering team.

Flomerics is what PTC calls a Platinum Advantage Partner because many of its programs integrate with PTC's software. In creating their new design, the Bronswerk engineering team needed to fully understand airflow patterns and compare them with those from older fans. According to Guus Bertels, senior engineer, "Our fans are large. Each profiled cross-section is thick, but tapers at the end to maybe half a millimeter. The numerical challenge of dealing with dimensions ranging from meters to less than a millimeter is enormous."

To make the system quieter, engineers improved the efficiency, but they were surprised by how much potential energy savings they achieved. According to Bronswerk, the company's new designs achieve up to 80 percent efficiency. The company says older systems can be expected to be about 60 percent efficient.

"Our challenge was to develop the quietest cooler system," Bertels said. "The added efficiency was an additional and unexpectedly huge benefit. Sometimes when you want to improve something, you can't just improve it a little bit."

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© 2007 by The American Society of Mechanical Engineers