Robots convert sludge to power

first_imgTEDs have many advantages over conventional cleaning processes. A properly designed system outworks three to five people. Furthermore, on-board lower-explosive-limit monitors, automatic sensors and emergency shut-down controls are more accurate and reliable than human workers, who must make judgments based on visual observation and personal experience. Robots can also work for extended periods of time and are largely unaffected by temperature extremes, poor visibility and lack of fresh air. Robots convert sludge to power Figure 2. TED robots reduce dangerous in-tank man-hours. 8.1.1995 Aging tank farms, repowering projects and environmental considerations are increasing the need for tank cleaning services at a time when waste disposal options are shrinking. Tank owners clean aboveground fuel storage tanks (AST) commonly to allow inspections and mechanical repairs, to eliminate downstream problems caused by fuel contamination, and to recover lost storage capacity and fuel trapped in sludge. Facebook Collins, Steven, and Roman, Harry T., Power, March 1993, pp. 90-96. A second new robot version enters the tank through a standard 8-inch flange on the tank roof. A rotating blending nozzle on a moveable suspension beam allows the roof-mounted robot to clean all tank areas. RELATED ARTICLESMORE FROM AUTHOR Robots convert sludge to power Cleaning and recovery process The process yielded 3.5 cubic yards of solids for disposal, reducing waste 99 percent by volume. Experience at PSE&G has shown that recovered oil value and cost savings from waste minimization can compensate for cleaning costs (Table 1). A new tank cleaning process incorporating robotics and However, human workers do have their role. Located in a climate-controlled, portable building outside the tank (Figure 3), a “robot pilot” (Figure 4) operates the unit via video remote control. Robots receive power and guidance from an electrically activated directional valve system with real-time responses to operator commands. References Linkedin At the same time, National Emission Standards for Hazardous Air Pollutants programs and further restrictions on solid waste disposal drive costs higher. In fact, all tank-bottom sludge may soon be designated as hazardous, landfill-banned material. As a result, tank cleaning is becoming more frequent, difficult, restricted and environmentally driven. Paul Sievert is vice president of marketing for Lansco (Landry Service Company Inc.) of Houston, Texas. One new track-drive robot contracts into a position small enough to crawl through a manway. A special insertion chamber prevents vapor loss from the tank during robot entry. Once inside, the robot expands to full size and begins the cleaning operation. Conventional cleaning drawbacks A key to system efficiency is a family of proprietary remote-controlled robots (Figure 2), called tank entry devices (TED), that perform most in-tank work. The robots have a moveable nozzle for blending diluent and if fitted with a suction device, can pump liquefied sludge from the tank. If necessary, robots may also use a tractor blade to push sludge to satellite pumping locations. By Kevin P. Reimer, Public Service Electric & Gas Co., Paul Sievert, Landry Service Co. Inc., and Thomas H. Pratt, Burgoyne Inc. Click here to enlarge image Previous articlePE Volume 99 Issue 8Next articlePE Volume 99 Issue 9 chloecox Robots will also soon be able to work completely submerged, allowing the tank to remain in service while it is de-sludged. Furthermore, current prototypes expand the robot`s duties to include inspection, with the capability to measure metal thickness, porosity and corrosion. The robots produce information and images that are often more accurate and cost-effective than manned, visual inspection. Safety is another key concern with conventional cleaning. Working inside a tank is cumbersome and potentially hazardous to personnel, who must maneuver in dark, confined spaces wearing a bulky protective suit and breathing apparatus. The reclaimed fuel (valued at more than $60,000) contained less than 2 percent basic sediment and water, equivalent to the oil`s original specifications. There are also considerable long-term financial benefits from reduced liability associated with health and safety risks, environmental compliance and waste disposal. Exceptional fuel recovery Figure 3. (above) Operators control the robots from inside a climate-controlled portable building outside the tank. The new cleaning system integrates material removal with phase separation processing (Figure 1). A “blending” process liquifies the sludge by adjusting its viscosity with heat and dilution. The diluent or “cutter stock” can be any readily available light oil, but is usually No. 2 fuel oil or diesel fuel. An operator heats the diluent to approximately 140 F and pumps it at 100-120 pounds per square inch (psi) through an in-tank robot device. The operator controls blending carefully to keep the material at optimum viscosity-thick enough to hold solids, yet thin enough to be pumped efficiently from the tank. Vacuum pumps remove the blended sludge for further processing. TED`s excellent performance The centrifuge scrubs solid particles (as small as five microns) oil-free and drops them into roll-off boxes. The solids are dry, stable and non-hazardous. Pumps transport clarified oil to storage, usually in another fuel oil tank, where it is available for power generation. O&M Federal Register, Occupational Safety & Health Administration, U.S. Department of Labor, January 14, 1993, pp. 4462-4563. Then, crews of 20 or more (depending upon tank size and sludge volume) dig out semi-solid, unpumpable sludge with shovels or heavy equipment, hauling removed material to a landfill. In cases where sludge buildup is several feet deep, this procedure can take months to complete. Many times, workers cut large holes in the tank wall to allow front-end loader or dozer access. CEEM Information Services, Aboveground Tank Update, January 1993, p. 3. Optimizing Plant Performance: The April POWERGEN+ series activates today By chloecox – center_img Kevin P. Reimer is project construction manager for Public Service Electric & Gas Co. of Newark, N.J. and reduces downtime, cleaning and waste disposal costs Click here to enlarge image Previous robots required in-tank man-hours for robot assembly. However, a new generation of robots enables “virtual entry” capabilities, for which no manned entry is required. After removing virtually all residual oil, the operator washes the tank interior with clean, heated cutter stock, using the robot to direct spray at the small amount of remaining oil. A final wash using a high-pressure system (3,000 psi) removes any residual hydrocarbon, leaving the tank clean, oil-free, gas-free and ready for inspection and hot work permitting to eliminate explosion risk. AST regulation Stevenson, Jim, Pipe Line Industry, August 1994, pp. 40-42. These long-awaited advances in tank cleaning will help PSE&G and other utilities keep pace with increasingly stringent environmental, health and safety regulations while meeting the need for more cost-effective tank maintenance. END PSE&G first used the new technology on Bergen station`s Tank No. 1, which contained approximately 6 inches of semi-pumpable sludge. The utility recovered 4,180 barrels of No. 6 fuel oil, available immediately for use in the station`s burners. No posts to display In the past, cleaning an AST was a costly, labor-intensive task in which workers removed sludge manually for disposal. New technology has opened the door to faster, safer and more environmentally responsible AST cleaning. Now, tank owners can clean ASTs using advanced robotics, recovering and recycling a majority of the oil for power generation. While tank cleaning needs increase, stringent safety and environmental regulations restrict the cleaning options and methods available. Revised confined-space entry rules from the Occupational Safety and Health Administration demand greater liability for tank owners regarding permanent and contract employee safety. CEEM Information Services, Aboveground Tank Update, April 1993, pp. 1-3. Click here to enlarge image The cleaning and recovery process handles a wide variety of tank sizes and designs and has been effective with numerous hydrocarbon materials, including No. 6 fuel oil and diesel fuel. Authors Public Service Electric & Gas Co. (PSE&G) evaluated tank cleaning technologies extensively before selecting a patented system from Landry Service Co. that integrates robotic in-tank cleaning with a fuel recovery process based on centrifugation. Field results from the system demonstrated fuel recovery rates as high as 98 percent while reducing waste more than 90 percent by volume. The system also reduced in-tank man-hours drastically, resulting in greater efficiency (three to five times faster than conventional methods) and improved worker safety. Figure 4. (left) Pilots maneuver the robots via video remote control using an electrically activated directional valve system. Twitter TEDs also offer improved safety over conventional methods. The robot`s design eliminates possible ignition sources, combustible mists and electrostatic charges. In “high-risk” tanks, such as those where air emissions from tank venting or fears of pyrophoric materials preclude gas-freeing, a unit can work under a nitrogen blanket or other inert atmosphere. Most important, robots drastically reduce the number of in-tank man-hours. Click here to enlarge image Figure 1. The tank cleaning and phase separation process can reduce waste 99 percent by volume. Twitter The danger of explosion is always present, as are the long-term effects of toxic substance exposure. Reducing man-hours (and more importantly, high-risk, in-tank man-hours) is critical to the utility and the cleaning contractor. The operator further dilutes the sludge, then superheats it above 200 F, finally processing it in a high-speed centrifuge. Unlike conventional processing, this method adds no filter media, stabilizers or foreign solids during processing, yielding true waste minimization. TAGSFPLPE Volume 99 Issue 8 Thomas H. Pratt, Ph.D., PE, is vice president of Burgoyne Inc. of Marietta, Ga. The need to schedule AST cleaning more frequently is growing. Several bills before Congress would create federal guidelines requiring periodic out-of-service AST inspection. Pennsylvania and Florida have tough, proactive legislation already in place. A light-sensitive camera and lighting system provide video to the robot pilot. Just inside the manway, a second camera and lighting system, called a Camway, provides an overview of the tank`s interior and the robot. Vistra: Texas freeze caused $1.6B negative cash flow impact Roman, Harry T., Power Engineering, October 1992, pp. 66-69. Linkedin TED`s excellent future Facebook Ex-New York power market CEO named interim ERCOT CEO advanced phase-separation techniques improves safety Conventional cleaning brings about little waste reduction and offers virtually no opportunity to recycle fuel trapped in sludge. Conventional methods are also slow, inefficient and costly because they depend on manual labor. In a typical scenario, workers pump out free-flowing, liquid waste using vacuum trucks. Click here to enlarge imagelast_img