FLUID HANDLING AND FLUID POWER

This section was edited by Executive Editor Harry Hutchinson.

WRANGLING HOT WASTE

The Department of Energy's Hanford Site, near the Columbia River in Washington, has close to 150 aging waste-storage tanks that are being cleared out so their radioactive contents can be transferred to more-secure double-wall containers. The contractor, CH2M Hill, hired to safely manage this waste, including the job of transferring it to safer tanks, has developed a lot of specialized machinery for the task.

One of the big challenges of the cleanup is that all the tools or machinery to do the work must fit down a 15-foot-deep pipe that may be only a foot wide. A scissor-like device called the Salt Mantis, which uses high-pressure water jets to break up salt deposits, was discussed in this department in April two years ago. The latest machine designed to fit into the storage tanks combines the high-pressure water with a plow to move the freed waste.


Right fit: The Foldtrack in its extended form enters an above-ground test tank during trials at the Hanford nuclear waste site in Washington.

When it is ready for use, the new device, called Foldtrack, is essentially an 800-pound bulldozer 5.5 feet long and 30 inches wide. It is equipped with nozzles for high-pressure water jets that can scour the walls and floor of a tank. The vehicle has a plow blade that can move radioactive waste to make it accessible to a pump for removal. To fit through the access pipe, however, Foldtrack has to be able to change shape.

Its parts are hinged together so that they unfold to make a long, narrow chain. It can be lowered through the access pipe—first the tread assembly for one side, then the plow blade followed by the other tread. As it descends slowly into the tank, the entire assembly dangles from a thick umbilical that looks like a huge rat tail. The umbilical supplies power, control links, and water.

When the machine reaches the floor of the tank, it reconfigures itself into its working form. Each tread is powered by its own hydraulic motor. The folding and unfolding operations use a single hydraulic cylinder. The vehicle is controlled from a PC that can sit as far away as 800 feet.

Working form: This remotely controlled bulldozer, designed to work where no human being can, will apply water jets up to 3,000 psi to help remove nuclear waste from storage tanks.

Foldtrack carries two water jet systems to help remove waste and to clean tank walls. The front of the plow blade holds a four-nozzle manifold that can deliver water at 3,000 psi to loosen waste on the floor of the tank. A wall-cleaning jet articulates up to 40 degrees with the raising and lowering of the blade to spray water at pressures between 800 and 2,100 psi.

Cameras deployed inside the tank allow the operator to watch the unit as it is lowered to the tank floor and see whether it is in the right position or not. Foldtrack is geometrically designed to land in the right configuration to unfold, but should it land upside down, operators are trained to correct the situation and put it in the right orientation.

According to Rick Raymond, CH2M Hill's director of technology development, the device can reduce the amount of residual waste left in the tanks. "We expect Foldtrack to improve the quality of our waste retrieval program by speeding the process, reducing the cost, and improving protection of the environment," Raymond said.

The Foldtrack was designed by CH2M Hill's engineers working with Non Entry Systems Ltd., a company in Swansea, Wales, that develops remotely operated equipment for use in hazardous environments. The machine has been deployed in a demonstration tank at Hanford and is scheduled to enter service, in tank C-109, a 530,000-gallon tank, this month.

CLEARING THE AIR
 
The speed of injection molding is one of the advantages of the process. Parts by the thousands can be manufactured in an hour with precise detail and range of properties dependent on the chosen plastic. It seems that the speed, particularly the injection of plastic into molds, is also the cause of a manufacturing challenge: It's so fast that air gets in the way.

As Joseph Crowdus, vice president at Infinity Molding & Assembly Inc. in Mt. Vernon, Ind., told us, "Air in a mold is not good." Air caught in the mold can heat up when the plastic compresses it, and that can cause the discoloration called part burn. Trapped air can result in voids or other irregularities in parts.

Infinity cuts down on those problems by using a mold evacuation system called Mold-Vac to clear the air out of a mold just as the plastic is injected. Actually, it uses a half-dozen Mold-Vac units. The systems, which are marketed by CAE Services Inc. of Batavia, Ill., create a vacuum to draw air from the mold as plastic enters.

"They have been successfully employed on what we define as 'tough' venting applications—ones where we just cannot achieve part quality using normal approaches," Crowdus said. "As a direct result of using Mold-Vac units, we have experienced improved processing windows."

Besides vacuuming air out, Mold-Vac has a blowback feature that injects compressed air, first to help eject the part and then to clear the mold and vents of residue. According to CAE Services, the blowback reduces damage that can occur to parts when the mold is opened, and lengthens the time between shutdowns to clean molds.

Crowdus said he became aware of Mold-Vac when a business associate at another company used the system. Crowdus said he first tried Mold-Vac in the early 1990s.

"I was processing a difficult grade of clear, rigid PVC," he said. "The mold vent areas were dirty and effectively blocked after a few days of production. Based on my discussion with my business associate, I decided to give Mold-Vac a try."

Molds require a fitting to use Mold-Vac. According to Mark Solberg, CAE Systems' vice president for sales and marketing, any mold can be modified to accommodate the system.

The system is microprocessor controlled, and its various functions, including cycle time, vacuum strength, and blowback pressure, can be adjusted from a console.

Solberg said systems range in price from about $5,000 to $16,000, depending largely on the size of vacuum pump needed for the intended application.

BOOTS UP
 
Mom wouldn't send us to school in the snow or the rain without our boots. This is something like that.

Curtis Universal, a manufacturer in Springfield, Mass., advises customers to put boots on their ball and pin universal joints when operating conditions are harsh. That is, where materials like abrasives or chemicals can shorten the lives of moving parts. The company recommends boots for a long list of hard-working environments, from farm equipment to aggregate conveyors and bakeries.

The boots are flexible polymer covers for the joints. The company stocks a standard line of Neoprene covers, and takes special orders for joints booted with EPDM, silicone, or Viton fluoroelastomer.

Curtis says Neoprene, a DuPont synthetic rubber, is resilient, resists abrasion, tearing, and flame, and generally is unaffected by moderate chemicals, fats, grease, and many oils and solvents. It holds up in weather and exposure to ozone, and can operate in temperatures ranging from -65°F to 250°F.

EPDM stands up to steam and to heat as great as 350°F, but it exhibits poor resistance to oils and solvents. Curtis recommends it for low-rpm elevated temperature applications.

Silicone rubber's heat resistance ranges from -150°F to 550°F. It is highly resistant to oxidation and ozone attack, but puts up only fair to poor resistance to abrasion, tearing, and oil. Curtis suggests these boots made for low-rpm applications in extreme temperatures.

Viton, made by DuPont, is heat resistant to 650°F and resists a wide range of oils and solvents, as well as abrasion and tearing. Because the material is stiffer than the others, Curtis says that fluoroelastomer boots are best suited to high-temperature applications where the joint operates at a minimum offset angle.

Curtis recommends its U-joints for applications where misalignment exceeds 3 degrees, where torque is high and variable, or where the angle of misalignment changes during operation. The company says that one of its universal joints can negotiate a turn of as much as 35 degrees. Two joints working together can accommodate misalignment of 70 degrees.

The company does not recommend block-and-pin U-joints for use where rotating speed is more than 1,500 rpm at 10 degrees of misalignment. Places where the company says the U-joints do well include motor-driven actuators, adjusters for valves and hydraulic drives, augurs for moving grain and other agriculture products, conveyors for anything from crushed stone to manufactured parts, heavy-duty pumps, or turbine regulators.

$40 BILLION FOR CLEAN WATER

A market research company predicts that world demand for water treatment products will increase 6.4 percent a year to reach almost $40 billion in 2011. According to the company, The Freedonia Group Inc., growth in China and India may almost double the world increase in demand.

The company predicts greater increases in the sales of nonchemical water treatment equipment and supplies than in sales of chemical additives. Ultraviolet and ozone treatments have gained in popularity because they allow the treatment of water with fewer chemical additives, Freedonia said. Advanced treatments, including membrane separation, are also taking a larger share of the world market.

The Freedonia Group has published a 362-page report, World Water Treatment Products, which it is offering for sale at $5,800 a copy. Details are available from the company in Cleveland, Ohio, or at its Web site, freedoniagroup.com, under "World Reports."

WATER FOR POWER

Researchers at Sandia National Laboratories are working on a computer model designed to help decision-makers look at the trade-offs, including use of available water, when they plan for the power needs of an area.

The model will also be able to factor in other key concerns about a plant's environment, including access to transmission lines, distance to fuel sources, and receiving air shed conditions. But water is a major concern, especially in the rapidly growing areas of the American Southwest, according to the principal investigator, Vince Tidwell.

The aim is to permit planners to work out scenarios taking into account power needs and water availability on local, regional, and even national scales.

Electrical power generation in the United States draws about 140 billion gallons of water a day, primarily as coolant for thermoelectric plants, he said. That is about 40 percent of the withdrawals of freshwater for all purposes. Most of the water is not consumed and is returned to the watercourse, although at a higher temperature, he said. Nonetheless, the volume of water must be available if the power plants are to run, so access to water becomes a concern when deciding the location of a new plant.

The idea for creating the model arose from the Department of Energy's Energy-Water Roadmap Development Exercise, which studied issues facing the country because of power generation and its need for water. The roadmap is under review by the DOE and has not yet been published.

The research team plans to include tools to help in data analysis. Deciding the optimum sites for power plants might be influenced by considerations such as cost, availability of water, availability of fuels, access to transmission lines, and greenhouse or other gas emissions. The optimum type of plant might be determined by studying the need to minimize certain emissions and by a need to maintain a balance of energy sources-fossil, nuclear, and renewable.

IRAQ WAR REACTIVATES SOME OLD FUEL PROJECTS

A report by Frost & Sullivan links increased demand for heat exchangers in Europe to the Iraq war. According to the market research company, the war, which began in 2003, constrained oil supply and raised oil prices.

A number of alternative fuel projects that had been put on hold for years, involving gas to liquids, liquefied natural gas, and ethylene cracking, started to look good again. As a direct consequence, the company says, the demand for heat exchangers has increased significantly.

According to the report, European Heat Exchanger Market, revenues were $3.5 billion in 2006.

A Frost & Sullivan analyst, Kaushik Ghosh, sees expanding market share for plate heat exchangers. "Their popularity is growing mainly due to the advantages they hold over shell and tube categories," Ghosh said.

Plate heat exchangers are compact, can be modularized in different shapes and sizes, show increased efficiency in heat transfer, incur low installation and maintenance costs, and can withstand high temperature and pressure. Ghosh predicts that these advantages will lead to an increased replacement of shell and tube heat exchangers by plate heat varieties in the future.

He also sees the possibility of a scarcity of raw materials, which may raise the costs of heat exchanger manufacturers. They may have to raise prices to end users to save their profit margins.

TOPS IN PUMPS

The world market for industrial pumps was about $29 billion last year, and ITT accounted for almost 10 percent of the total, according to the latest report from McIlvaine Co., the market research firm. McIlvaine ranks 457 pump companies in Pumps: World Markets, a continually updated report available online. The top 10 suppliers of pumps did half the business.

The report predicts that the world market will grow to $37 billion in 2011. Contributing to this growth will be purchases in China for municipal wastewater treatment, drinking water, chemical, iron, and steel manufacturing. These are McIlvaine's top 10, with sales in billions:

ITT Ebara Grundfos Flowserve Sulzer Weir KSB Wilo AG Roper Industries Putzmeister

$2,741 1,681 1,660 1,618 1,438 1,403 1,214 1,153 1,106 740

McIlvaine, based in Northfield, Ill., makes its reports available through its Web site: www.mcilvainecompany.com.