Duke Power Co. in Charlotte, N.C., and the Electric Power Research Institute (EPRI) in Palo Alto, Calif., joined together to clean up a South Carolina manufactured gas plant. An integral part of the project was a solids feeding system manufactured by Stamet Inc. in Gardena, Calif., that managed the material handling for the project.

This solids feeder, which has only one moving part, delivers precisely metered amounts of fuel-rich soil to a boiler for burning

Duke used the feeding system to add measured amounts of soil that contains gas residues to coal for co-burning in one of the utility's power plants. Typically, the coal tar in the soil would be removed with some sort of conventional decontamination process. However, since this material does have value as a fuel, Duke and EPRI solved the cleanup problem and derived an inexpensive source of energy by burning the material. This process provides an alternative to other cleanup options that are more expensive.

To meet emissions standards, the state regulatory agency required a precisely controlled and metered feed rate for the material, so the solids feeding system was integral to the project. The coal-tar-contaminated soil being processed, however, is difficult to feed and meter because of its variable composition. The material is excavated, screened for size, and brought to the power-plant site. The mix is then blended with coal as it is transported to the bunker and delivered into the existing boiler system. It can constitute up to 5 percent of total feed.

Stamet provided a live-wall hopper, feeder, and conveying mechanism for delivering the waste material into the boiler. The feeder provided continuous, precisely metered delivery of solids--even into high pressures--and responds instantaneously to demand changes. The feeder has been successfully tested by feeding various solid materials into positive gas pressures of up to 210 pounds per square inch. The solids that were being pumped create both the sliding seal and the drive force. There is no metal seal to wear out as in conventional liquid pumps. The feeder has only one moving part: a smooth, durable spool that is designed to be self-cleaning and requires little maintenance.

Cleanup at the site began in August 1995 and finished late last year. The feasibility of using this process at other sites is being considered.

Tromsš, a tourist destination near the Arctic Circle, has connections to other Scandinavian countries via two airlines. The airport wanted an automated system capable of sorting passengers' baggage according to airline and class. The system had to handle baggage from 15 check-in positions.

The solution was a 260-foot-long Telebag system. A conveyor handling 18 self-guided vehicles operates around a loop that carries up to 2,800 articles per hour to 18 chutes for the sorting station. Each baggage item is automatically directed to its destination. The vehicles then return to their departure point to await new loading instructions. Each vehicle is identified by its electronic tag, which allows all movements to be tracked by computer using a two-way link incorporated into the center rail.

A conveyor with 18 linear motor-powered vehicles automatically sorts and delivers up to 2,800 bags per hour in a Norwegian airport

The system minimizes the number of interfaces between different operations. It handles the baggage as early as possible in the process and carries it as far as possible without any breaks in the chain. Another advantage is that two pieces of baggage can be front-loaded at the same time. The vehicles are loaded from a 3.3-square-foot conveyor, and two articles deposited at the same check-in can be carried together.

At the check-in desk, baggage is transported on three conveyor belts. It is placed on the first conveyor for weighing and transported to the second for labeling. It then passes to the third conveyor, which sends it into the sorting system. The first available vehicle is then automatically dispatched to receive the baggage.

The system monitors the demands of all check-in desks, scheduling each task so that vehicles do not obstruct each other during loading. It also determines the number of vehicles required at each moment so that the first is sent to the conveyor station farthest from the vehicle waiting area and the last goes to the nearest station.

Telebag vehicles are driven by two linear motors and can continue to operate if one motor fails. The base of the vehicles acts as the inductor that interacts with two lateral plates. Electrical power for the vehicle is drawn from the center rail. The track superstructure consists of three sections: straight; narrow radius, for reduced speeds; and large radius, for speeds of more than 16 feet per second.

The recorder, manufactured by RS Technologies Ltd. in Farmington Hills, Mich., measures fastener, joint, and tool characteristics. It can test torque/ tension verification on fasteners and joints, provide fastener torque/angle signature analysis for clamp force verification, and handle transducer calibration and tool-room calibration of power tools and torque wrenches. The recorder can also perform dynamic monitoring of power tools on the plant flow and certify calibration factors for single spindle nut runners and tools monitoring the reference transducer and tool transducer simultaneously.

The recorder includes two transient inputs--with a range of ±0.5 millivolts to ±10 volts--and two angle inputs. It can collect up to 1,000 rundowns and capture and display both real-time and peak readings. A real-time torque- angle, torque-clamp load, or torque-time graph is simultaneously displayed on the LCD screen with the peak/track readings.

This compact gear motor, which can deliver up to 720 inch-pounds of torque, was used to move a heavy automatic teller machine

Although several kinds of motors could accomplish the task of moving an ATM, the available space is very limited, which cuts down on the number of prospective designs. Also, because the ATM's safe is very heavy, high torque is needed. Bison's Series 650 gear motor, which measures only 5 by 61/4 by 53/4 inches, delivers up to 720 inch-pounds, twice the power normally found in units of this size.

The motor repositions the roller-mounted unit each day so a bank employee can service the machine. The motor's slow speed means that each operation takes several minutes, but time was not critical for this application. Alternatives cost more and took up more space.

The gear motors withstand occasional peaks of up to 250 percent of full-load torque. Gear ratios start at 11:1 and have a high of 2,206:1. The gearbox offers up to five stages, whereas conventional units this size have four or less.

The speed of the gear motors ranges from 0.7 to 3 rpm. Combined with its high torque capabilities, the motor offers particular benefits in such applications as conveyor systems, food-processing equipment, pallet-wrapping equipment, swimming-pool cover drives, solar heating, and floor-cleaning equipment. The slow-speed capability eliminates the need for double-gearbox combinations.

In a machine that manufactures shirts, positioning cutting and sewing mechanisms is extremely critical; a stitch out of place will cause the garment to be labeled a less profitable irregular. To help move fabric through the machine accurately, a large garment manufacturer uses the ZF Servoplan transmission by ZF Industries Inc. in Vernon Hills, Ill.

The low-backlash ZF Servoplan transmissions are designed for any positioning system. Mounted on the end of the servomotor, they are intended for uses where precision and repeatability are important. The system's accuracy helps ensure that each stitch and cut is made at the correct point as the fabric moves through the machine.

The transmissions are distinguished by their use of helical gears, which ensure low operating noise and high efficiency. The sealed-for-life lubricant promotes maintenance-free operation. In addition, the units deliver a high power-to-weight ratio and are noted for their compact size, cool running, and simplified direct-mount characteristics. Low-inertia torques and high torsional rigidity allow for fast, efficient movement with high levels of precision.

Another design advantage is the ability to overcome the loss in dynamics that could otherwise accompany the use of larger motors. The situation can now be avoided by stepping down to smaller motor sizes without a loss in performance.

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© 1997 by The American Society of Mechanical Engineers