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IN THIS VOLUME


2004;():1-2. doi:10.1115/NAWTEC12-2199.

Sustainable cities require the generation of electrical energy from those fractions of wastes that cannot be economically reused or recycled, including the “carbon dioxide neutral” biomass components. The energy content of these solid materials can be recovered by burning directly or after processing into refuse-derived fuel (RDF). Alternatively, the combustion process can be staged by the production of intermediate fuels using either pyrolysis or gasification. Co-processing of the material with coal generally increases plant utilisation and thus reduces costs.

Commentary by Dr. Valentin Fuster
2004;():3-4. doi:10.1115/NAWTEC12-2200.

This panel session reviews a topic of long-standing interest and importance to the municipal waste combustion industry; how can some or all of the ten percent (10%) by volume of incoming material that remains after municipal solid waste is combusted be productively reused? This panel will address various reuse related topics, including but not limited to the following: • Pinellas County, Florida hosts a regional program where recovered ferrous metals from municipal waste combustors are shredded and recycled; an overview of experiences, economics, and logistics will be presented. • The Pennsylvania Department of Environmental Protection (PADEP) will discuss the technical and regulatory background behind a September 2003 Consent Decree entered with American Ash Recycling for removal of residual materials in York County, Pennsylvania. • The City of Tampa has short-listed two (2) companies for what promises to be a precedent-setting ash reuse program; a status report will be given. • SUNY Stony Brook’s Waste Reduction and Management Institute’s work on two demonstration programs using processed MWC ash (using processed MSW combustor ash in both cold mix asphalt and construction quality cement blocks as well as a concrete block demonstration program) will be discussed. • Florida Department of Environmental Protection’s (FDEP’s) multifaceted program to address municipal combustion ash residue beneficial use determinations, ash regulation changes, and its analysis of statewide total metals data will be reviewed.

Topics: Ash reuse
Commentary by Dr. Valentin Fuster
2004;():5-6. doi:10.1115/NAWTEC12-2201.

In the 1980’s, California faced landfill siting problems and a projected shortage of landfill capacity that could impact the health and safety in California. To address this issue, the California Integrated Waste Management Act was passed in 1990 and established a framework to limit reliance on landfills. This framework gives greater emphasis to recycling, waste prevention, source reduction, and composting. The Integrated Waste Management Act required each city and county to implement plans to divert 25% of solid waste by 1995 and 50% by 2000 from landfills. Although we have achieved a 47% diversion rate and have 170 composting facilities, we still have approximately 30 millions tons of material being landfilled. This may be an untapped resource for energy and alternative fuels production.

Commentary by Dr. Valentin Fuster
2004;():7. doi:10.1115/NAWTEC12-2202.
FREE TO VIEW

The potential for global climate change due to the release of greenhouse gas (GHG) emissions is being debated both nationally and internationally. While many options for reducing GHG emissions are being evaluated, MSW management presents potential options for reductions and has links to other sectors (e.g., energy, industrial processes, forestry, transportation) with further GHG reduction opportunities.

Commentary by Dr. Valentin Fuster
2004;():9. doi:10.1115/NAWTEC12-2203.
FREE TO VIEW

Montenay Inc. has operated the Greater Vancouver Regional District’s (GVRD) Waste-to-Energy Facility since it began commercial operation in 1988. The facility has a throughput of 720 tonnes (800 tons) per day in three lines. It utilizes Martin grate technology and dry lime injection with a reverse pulse jet fabric filter. The original facility design did not include a steam turbogenerator for energy recovery. The facility produced process steam at near saturation temperature to supply a recycle paper mill. The aging mill has reduced the fraction of steam used in recent years. This caused the GVRD and Montenay Inc. to cooperate in a major facility upgrade that began in 2001 and was completed in August of 2003. The complete project includes a turbogenerator, major boiler improvements and modernization of the boiler controls, while continuing to service the recycle paper mill.

Commentary by Dr. Valentin Fuster
2004;():11. doi:10.1115/NAWTEC12-2204.
FREE TO VIEW

The Savannah Waste-to-Energy Facility (the Facility) is a mass burn waste-to-energy facility with a processing capacity of 624 tons per day. The Facility commenced commercial operation in 1987, as a public-private partnership with the Resource Recovery Development Authority for the City of Savannah, Georgia. In April 2002, Montenay took over operation of the Facility from Katy-Seghers, continuing the established partnership Katy-Seghers had with the City of Savannah. This paper presents a case study of a successful change in operator for a waste-to-energy facility, detailing the hurdles crossed transitioning operation of the Facility to Montenay.

Commentary by Dr. Valentin Fuster
2004;():13. doi:10.1115/NAWTEC12-2205.
FREE TO VIEW

American Ref-Fuel Company (ARC) spends millions of dollars each year on corrosion related costs in the boilers. The corrosion is caused by chloride salts in the slag that deposit on the boiler tubes, coupled with the high temperatures of flue gas going through the boiler. Corrosion rates are known to be very sensitive to the flue gas temperature and velocity, surface temperature and heat flux through the slag, oxygen in flue gas distribution, etc. These parameters are primarily determined by the firing rate of the boiler, and they are also affected by combustion control and air distribution in the boiler. Some design parameters, such as surface area of refractory, tile, and inconel overlay, also affect the flue gas temperature throughout the boiler, and thereby impact corrosion.

Commentary by Dr. Valentin Fuster
2004;():15-22. doi:10.1115/NAWTEC12-2206.

The combustion of municipal solid wastes for generating electricity (Waste-To-Energy) has been recognized by several states as a renewable source of energy. Yet, there has been determined opposition by some environmental groups to including WTE in the portfolio of renewable energy sources that will benefit from a tax credit designed to decrease reliance on non-renewable fossil fuels. While WTE is considered worldwide as a solid waste management option, the recognition and acceptance of WTE as a clean source of energy still requires public involvement and education. This paper will examine the “pro” and “con” arguments for considering WTE as a renewable energy source.

Topics: Waste-to-energy
Commentary by Dr. Valentin Fuster
2004;():23-40. doi:10.1115/NAWTEC12-2207.

Following a 1986 decision by Montgomery County in Maryland to construct a municipal waste resource recovery facility near the town of Dickerson, the local community expressed concern regarding the potential human health effects from air emissions of dioxins and trace metals released through the stack of the proposed facility. To address this concern, the County conducted health risk studies and ambient monitoring programs before and after the facility became operational. The purpose of the health risk studies was to determine potential cancer and non-cancer risks to the nearby residents from the operations of the facility. The purpose of the ambient monitoring programs was to determine if any changes would occur in the ambient levels of certain target chemicals in the environmental media, and if such changes can be attributed to the operations of the facility. Accordingly, the County conducted a multiple pathway health risk assessment in 1989 prior to the construction of the facility. The pre-operational health risk assessment was based on estimated stack engineering parameters and available stack emissions data from municipal waste resource recovery facilities that were operating in the United States, Canada and Europe during the 1980’s. The health risk assessment used established procedures that were accepted by the U.S. Environmental Protection Agency (U.S. EPA) and many state agencies at that time. The Montgomery County Resource Recovery Facility (RRF) became operational in the spring of 1995. The facility is equipped with the state-of-the-art air pollution control (APC) equipment including a dry scrubber-fabric filter baghouse system to control organics and trace metals, ammonia injection system to control nitrogen oxides, and activated carbon injection system to control mercury. In 2003, the County retained ENSR International to update the 1989 health risk assessment study. In the 2003 operational-phase update, as-built engineering data and measured stack emissions data from a total of eighteen quarterly stack emissions tests were used. The study was conducted in accordance with the U.S. EPA’s Human Health Risk Assessment Protocol for Hazardous Waste Combustion Facilities published in 1998 [1], and an Errata, published in 1999 [2]. Both the 1989 study and the 2003 study demonstrated that there is a very low chance (less than one chance in a million) for occurrence of cancer and no adverse non-cancer health effects to the nearby community as a result of exposure to facility-related emissions. The multi-media ambient monitoring programs were conducted in abiotic and biotic environmental media. These programs included an air-monitoring component and a non-air monitoring component. The pre-operational phase of the air media and non-air media monitoring was conducted in 1994–1995. The pre-operational program was designed to produce baseline data for target chemicals in both air and non-air media. The operational-phase air media monitoring was conducted in 1997 and 2003. The operational-phase non-air media monitoring was conducted in 1997 and 2001. Target chemicals monitored in both air and non-air media included polychlorinated dioxins and furans (PCDDs/PCDFs) and selected toxic metals (arsenic, beryllium, cadmium, chromium, lead, mercury, and nickel). The non-air media included crops, farm pond surface water and fish tissue, and cow’s milk. The ambient levels of target chemicals monitored in the operational phase of the facility (1997, 2001 and 2003) demonstrated no measurable difference from the ambient levels of these chemicals monitored in the pre-operational phase (1994–95) of the facility, in both the air media and non-air media. The results of the health risk studies and ambient monitoring programs demonstrate that municipal waste combustion facilities that are equipped with the state-of-the-art air pollution control equipment pose no significant health risk to the population.

Commentary by Dr. Valentin Fuster
2004;():41-46. doi:10.1115/NAWTEC12-2208.

The Southernmost Waste-to-Energy Facility, is a 150 ton per day, stoker fired, mass burn facility located on Stock Island in the City of Key West, Florida. The facility is owned and operated by the City of Key West and is categorized as a Small MWC, Class II facility under the Emission Guidelines for Existing Small Municipal Waste Combustors, 40 CFR 60 subpart BBBB. In order to reliably comply with the requirements of the small MWC regulations, the facility air pollution control trains were required to be retrofitted to include acid gas control and improved particulate control through the installation of scrubbers and baghouses. Additional controls for metals including mercury may have been added in order to assure compliance with these regulations. Other facility upgrades including combustion enhancements may have been required to assure compliance with allowable carbon monoxide limitations of the Small MWC regulations. The need for the air pollution control retrofit project represented a major expenditure for the City of Key West. Faced with a decision regarding its long term future waste handling and disposal methods, the City examined various options for future solid waste handling and disposal including the option to proceed with retrofitting the waste-to-energy facility and relying on waste-to-energy as a long-term major component of Key West’s solid waste handling and disposal plans. Alternatively, the City explored the option of building a transfer station, either privately or publicly operated, and contracting the hauling and disposal of the City’s waste to a private firm. The transfer station option would require a conversion of the waste-to-energy facility to a transfer station through a major demolition and reconstruction project. The City also considered available alternative technologies such as gasification for example. In order to help the City sort through the many issues associated with the solid waste handling and disposal options, a Technical Advisory Committee was formed consisting of engineering and legal consultants, City commission members, and other City representatives. Dvirka and Bartilucci Consulting Engineers, as a member of the Technical Advisory Committee, was responsible for estimating the costs associated with the design, construction and operation of a waste-to-energy facility air pollution control retrofit project. This paper describes the facility and discusses the decision making process of the technical advisory committee and the ultimate decision of the City Commission to close the Southernmost Waste to Energy Facility. The paper includes the requirements for closure of the facility and discusses how the City arrived at its final decision.

Commentary by Dr. Valentin Fuster
2004;():47-53. doi:10.1115/NAWTEC12-2209.

The twenty-three communities that comprise the North East Solid Waste Committee have labored under what may well be the worst municipal solid waste service agreement in the country. In FY 2004, the disposal fee is $140 per ton. Over the past eighteen years, the communities have paid more for disposal, as much as two to three times what the neighboring communities have paid. The NESWC Board of Directors has, over the course of the past ten years, implemented a multifaceted program to reduce the environmental and economic burden associated with managing the municipal solid wastes generated in the 23 member communities. The program has included a series of innovative approaches to obtaining negotiating leverage and support from diverse stakeholders to reduce the cost and implementing innovative programs to help reduce the amount and toxicity of waste requiring disposal. What makes this particularly significant is that it was done on a regional basis, involved interaction with a broad, diverse group of stakeholders at the local, state and federal level and required the use of a wide array of change inducing tools, including arbitration and litigation, to achieve the results. Most recently, the communities and the vendor, Wheelabrator North Andover, completed negotiations regarding service post termination of the existing Service Agreement in September, 2005. This paper updates key lessons learned over the past decade.

Commentary by Dr. Valentin Fuster
2004;():55-59. doi:10.1115/NAWTEC12-2210.

The market for new waste-to-energy (WTE) facilities in the United States has been extremely limited because the playing field has become uneven. The industry’s traditional playing field has been defined by economics on one end of the field and public perception on the other. However, a third, nearly impenetrable “red zone” has appeared, defined by government policy inconsistency. Examples include landfill gas being given tax credit status while WTE continues to be excluded; the removal of the moratorium on landfill capacity in Massachusetts while maintaining the moratorium on new WTE capacity; and DOE’s support of unproven gasification technologies without parallel support for optimizing long-proven WTE technologies. This record of inconsistency keeps WTE on the back porch of public perception and separated from political acceptance as an important renewable energy strategy. This paper challenges the WTE industry to collectively pursue a more aggressive stance with governments to prove that the playing field has become uneven and to shift public policy, including test program funding, as a means to level the playing field. Presented in the paper are overviews of EAC’s next-generation large-scale and small-scale resource recovery technologies, including patent-pending features for the achievement of zero disposal and zero pollutant emissions, all of which are based on practical answers to real-world problems and perceptions. The paper concludes that the WTE industry has accepted as conventional wisdom barriers that are not valid constraints to new project development. Examples of current conventional wisdom include the assumption that WTE facilities must always be sited away from commercial centers at the expense of thermal efficiencies offered by co-generation of electricity and district heating/cooling; WTE will always be landfill dependent at the expense of real consumer products from byproducts; and emissions will never be able to compete in the future because of certain pollutants. All of these barriers can be breached on an even playing field with creativity, cooperation, and credibility.

Topics: Waste-to-energy
Commentary by Dr. Valentin Fuster
2004;():61-73. doi:10.1115/NAWTEC12-2211.

Waste to energy is only one way of handling waste, material recovery is another aspect of sustainable waste management. This is actually nothing new and has always been part of the operation of WTE (Waste to Energy) plants in Hamburg. In descriptions of the first waste incineration plant in Hamburg, which started operation in 1896, it was stated that “the fly ash” collected in the ash chambers was used as filler material for the insulation of ceiling cavities. Its use in the sandwich walls of money safes was expressly recommended by the members of the urban refuse collection authority. Another lucrative trade was the sorting of scrap iron. It was separated from the incineration slag with magnets. The slag itself was said to be as sterile as lava, as hard as glass, as useful as bricks, and it was a profitable side product of waste incineration. The crushed incinerator slag was evidently so much in demand in road construction and as an aggregate in concrete production that demand could often not be met in the building season, even though it was stored through the winter, [1,2,3].

Commentary by Dr. Valentin Fuster
2004;():75-82. doi:10.1115/NAWTEC12-2212.

In the U.S., about 28.5 million tons of municipal solid waste are combusted annually in waste-to-energy facilities that generate 25–30% of ash by weight of the MSW feed. Since some residues were found to contain high levels of lead and cadmium prior to the 1990s, they were commonly associated with environmental pollution. However, for the last years nearly all ash samples have been tested non-hazardous. Research on the beneficial use of combustion residue has been conducted for the past few decades yet the actual ash reuse rate in the U.S. has remained close to 10%. Currently most of the ash is landfilled at considerable cost to the waste-to-energy industry. A consortium of researchers at Columbia University, the State University of New York at Stony Brook, Temple University, and other institutions seeks to develop and to advance the beneficial uses of combustion residues, such as in construction materials or remediation of contaminated abandoned mines and brownfields. This paper describes the search for beneficial use applications and provides an overview of the first year of this consortium.

Topics: Waste-to-energy
Commentary by Dr. Valentin Fuster
2004;():83-89. doi:10.1115/NAWTEC12-2213.

The objective of the paper is to outline a new business-oriented methodology based on the principle of diagnosing before improving and with the aim to produce long-term results that mutually benefit the owner and the operator of a Waste-to-Energy or biomass plant. The scope covers (1) the determination of correction curves and coefficients for various operating conditions to compare actual equipment performance with design one (with illustration for a steam turbine); (2) the mapping of the yearly plant operation schedule into different operating modes, for a better evaluation of dollar benefits of improvement solutions; (3) the use of a computerized plant simulator model that performs heat and mass balances and translates available monitoring data into dollar value. When benchmarking the illustrated plant case study with industry standards, we found out that reducing the Deaerator pressure by 40 psi (by 2.7 bar) would translate into an expected additional $850k of total benefits a year.

Topics: Waste-to-energy
Commentary by Dr. Valentin Fuster
2004;():91-98. doi:10.1115/NAWTEC12-2214.

The combustion of municipal solid waste in a boiler for power generation produces a very corrosive environment for the boiler tube materials. The environment contains HCl, SO2 , various metal chlorides and sulfates along with typical combustion products. Due to their low melting points and high vapor pressures, metal chlorides are believed to be primarily responsible for the boiler tube corrosion problems encountered in waste-to-energy (WTE) boilers. Without some sort of corrosion protection method, the standard materials of the construction for the boiler, such as carbon and Cr-Mo steels, are subject to severe high temperature corrosion attack. The present paper discusses the possible modes of high temperature corrosion for waterwalls and boiler tubes in the convection section, and the prevailing protection method for these components as well as the performance of various alloys in these hostile combustion environments.

Commentary by Dr. Valentin Fuster
2004;():99-109. doi:10.1115/NAWTEC12-2215.

Municipal solid wastes (MSW) typically contain plastic materials, leather, textiles, batteries, food waste and alkalis. These materials are sources of chlorine, sulfur, potassium, zinc, lead and other heavy metals that can form corrosive media during combustion of the MSW in waste-to-energy (WTE) facilities. Chlorides and sulfates, along with fly ash particles, condense or deposit on the waterwall surfaces in the combustion chamber and on other heat exchanger surfaces in the convection path of the process gas, such as screens and superheater tubes. The resulting high corrosion spots necessitate shutdowns and tube replacements, which represent major operating costs. The aim of ongoing research at Columbia University is to gain a better understanding of the effects of fuel composition, products of combustion, and chemical reactions that lead to the corrosion of metal surfaces in WTE boilers. The potential chemical reactions and their chance of occurrence were determined by means of thermochemical calculations of the respective equilibrium constants as a function of temperature and gas phase composition.

Commentary by Dr. Valentin Fuster
2004;():111-119. doi:10.1115/NAWTEC12-2216.

Corrosive conditions in waste to energy boilers produce rapid wastage rates of traditional boiler tube materials. It is not unusual to see corrosion rates in the range of 1 to 3 mm/y (40–120 mpy) on carbon steel boiler tubes and occasionally corrosion occurs at even higher rates. In the mid1980’s there were several boilers that experienced corrosion failures of carbon steel waterwall tubes in less than 6 months of service (1,2). Because of this experience, it has become accepted that some type of corrosion protection is required for boiler tubes in refuse-to-energy boilers. Over the years, many different alloys have been evaluated to improve tube life in waste-to-energy boilers. The most successful materials used for corrosion protection are nickel alloys.

Commentary by Dr. Valentin Fuster
2004;():121-128. doi:10.1115/NAWTEC12-2217.

The Maine Energy Recovery Company is a refuse derived fuel (RDF) waste to energy facility that began commercial operation in 1987. The facility consists of an RDF production operation, two B&W boilers which produce 210,000 lb/hr of steam at 650 psig/750F with a design Furnace Exit Gas Temperature of 1700 F, and a 22 MW steam turbine generator. Since startup, the facility has suffered fireside erosion/corrosion of the waterwalls, superheater, and generator bank hot side sections. Through the years, Maine Energy has made various operational and design changes in order to improve combustion and overall boiler availability. While combustion has improved as evidenced by improved emissions, reduced supplemental fuel usage, and lower ash production, superheater availability has suffered. At the same time reliability of the waterwall and generating bank components have improved. This paper will present a history of Maine Energy’s efforts to improve its superheater availability including a summary of the tube wastage rates for various superheater alloys, as well as Maine Energy’s plans for its superheaters.

Commentary by Dr. Valentin Fuster
2004;():129-136. doi:10.1115/NAWTEC12-2218.

Some domestic waste incinerators [1] have operated successfully with refractory tile systems for tube protection without using mortar to bond the tiles to the tube walls. Most tile protection systems installed around the world employ a paste of mortar behind the tiles to develop a rigid fixing system, with the presumption that the mortar provides another layer of tube protection behind the tiles. This paper examines the issues behind these approaches to tube wall protection and propose some guidelines for the use of refractories in these systems.

Topics: Mortar , Tiles
Commentary by Dr. Valentin Fuster
2004;():137-143. doi:10.1115/NAWTEC12-2219.

International Waste to Energy and Incineration markets are likely to continue to grow in capacity over the next 5 to 6 years. With this comes a greater need to burn more corrosive materials combust at higher temperatures and extract more energy. The reliability burden that this places on operators of plants will re-open opportunities for thermal spray solutions. Where maintenance costs, opportunity costs and access restrictions may preclude alternative in-situ technologies, thermal spray technology may fill a gap in providing new reliable and flexible process and materials technologies for at least the midterm protection of water wall and superheater tubes. The state of the art of the technology is such that coating performance in WTE corrosive environments now approach the performance of corrosion resistant wrought materials. This is verified through accurate laboratory modeling and scale tests and trials conducted by OEM’s and plants.

Commentary by Dr. Valentin Fuster
2004;():145-151. doi:10.1115/NAWTEC12-2220.

Due to serious deterioration of aluminum fins on two dry coolers only 6 years after initial installation, the potential to disrupt operation of the 3,000 tons per day (tpd) Pinellas County Resource Recovery Facility was a real concern. A new system upgrade was required to provide reliable cooling of the glycol liquid system. This system dissipates the heat rejection requirements of the process and instrument air compressors, particularly critical during Florida’s hot summer months. A second issue was the need to provide redundancy, which was not designed into the original installation. The selected system included two plate and frame coolers along with two pumps located next to the existing cooling tower (C.T.) basin. Water from the C.T. basin is pumped through one plate and frame cooler, reducing the temperature of the glycol liquid. The water then flows back to the C.T. basin. The construction work, completed in August 2003, provides in excess of 200% redundancy and has been in successful operation since that date.

Commentary by Dr. Valentin Fuster
2004;():153-159. doi:10.1115/NAWTEC12-2221.

An energy audit can mean many things to many different people. For some, an energy audit or assessment means focusing on processes, operations, or equipment. This particular audit was directed toward the brick, refractory, and insulation, and its direct effect on the boiler’s efficiency, reliability, and energy fuel savings. Compared to most components found on a steam-generating boiler the cost of the materials and the installation of the refractory or brick are very small (less than 1% of the total cost of a new boiler). Yet, when properly designed, specified, stored, installed, cured or dried, refractory will save as much as five to seven percent in annual fuel cost (oil, gas, coal, refuse). Refractory and brick problems are found on most steam-generating boilers. These problems directly affected the amount of fuel used to meet heat and steam requirements. A boiler will always use more fuel if the brick and refractory are not installed correctly. After all the changes and corrections were made it was estimated that there will be an annual fuel savings of approximately $100,000 per year. This is why experts say, “Brick and refractory installed to save energy also saves money at a rate that is essential for efficient plant operation.”

Commentary by Dr. Valentin Fuster
2004;():161-180. doi:10.1115/NAWTEC12-2222.

The boiler generating bank (convective) sections of waste to energy boilers are commonly found to be very limited in regards to personnel access. The Miami-Dade County Resources Recovery Facility has had a challenge in the past to effectively clean this section of the boiler either on line or within a timely manner during outages. In 2003 the company used a new innovative method for cleaning this section off line. The boilers were 100% clean in 1/2 to 1/3 the usual time. The new method involved high-pressure industrial water blasting as typically used, with the exception of the water delivery device/system. Normally the water delivery method involves personnel placed in the boiler with hand held high-pressure water lances. They require confined space monitoring, lighting, scaffolding, proper air supply, frequent breaks, rain suits, full face shields and other PPE for safety inside the boiler. These factors combined with the limited space severely constrain the personnel and their effectiveness when using the water lances. Cleaning is compromised and has led to poor effectiveness and long duration cleanings. Explosives have also been tried to help augment cleaning. The new method used in 2003 involved no personnel in the boiler. Instead, for the water delivery system, a support cable is erected across the boiler upon which a rotary cable swivel tool (CST) is mounted. The tool has connections for high-pressure water and plant air and a simple winch for traversing the tool across the furnace. Very effective cleaning was accomplished from drum to drum, a distance of 20 feet (6.1 m). Depending on the application, the water pressure can be adjusted for maximum effectiveness. The air pressure is also adjusted to control the speed at which the rotary nozzles spin to best match the fouled conditions. The orientation and number of nozzles is also optimized for each application. This paper details the results of using the rotary Cable Swivel Tool (CST) in the generating bank section of the boilers and discusses related operational and maintenance benefits.

Topics: Cables , Boilers
Commentary by Dr. Valentin Fuster
2004;():181-198. doi:10.1115/NAWTEC12-2223.

The boilers’ generating bank (convective) section began suffering repeated random failures at the Miami-Dade County Resources Recovery Facility. The plant embarked on an optimization program to better identify and target the failures using non destructive ultrasonic Internal Rotary Inspection Services (IRIS) testing. Through the use of the IRIS nondestructive testing method, the plant was able to identify 3 major contributors to tube failures by mapping out the locations of the tube wastage across all 4 boilers at the facility. The testing allowed optimizing the use of resources allocated to this area of the boiler and resulted in a considerable drop of unscheduled downtime and increase in generating bank tube reliability. The IRIS testing method involves an ultrasonic probe that is lowered down the inside of the tubes. The tubes are flooded with water in order to get a full 360-degree thickness survey of the tubes from top to bottom, (steam drum to mud drum). The data for over 4.7 miles (7.5 Km) of linear tube per boiler is recorded digitally and presented on a CD. By pinpointing the location and severity of tube wastage across the entire generating bank section, the root cause of the failures could be identified. An integrated solution was developed involving a combination of tube replacements, shielding, tube plugging, and soot blower optimization. This paper summarizes the results of the testing and optimization program.

Commentary by Dr. Valentin Fuster
2004;():199-204. doi:10.1115/NAWTEC12-2224.

Wheelabrator Technologies is owner and operator of the 2250 ton per day North Broward County, Florida, facility. The plant consists of three lines rated at 750 tons/day. Each line is equipped with a spray dryer absorber/fabric filter. The original fabric filter design was a shake-deflate baghouse with ten compartments of 180 bags each. The typical bag life was one year with the shake-deflate baghouse using standard woven fiberglass bags. Frequent bag failures led to high operating and maintenance cost for the system. The initial upgrade was a conversion from a shake-deflate baghouse to a reverse-air baghouse with sonic horns. The resultant bag life was improved to two years, which represented a significant reduction in maintenance cost. The latest upgrade for the baghouse system was the installation of PTFE membrane/fiberglass filter bags. The change in the filter media resulted in a dramatic improvement in performance. The baghouse cleaning frequency dropped from 360 cycles per day to approximately 50 cycles per day. The average differential pressure across the baghouse system also dropped by 6 in. w. g. The membrane filter bags have achieved over two years life to date and have significantly reduced operating and maintenance costs associated with the baghouse. This paper will detail the steps taken in the conversion from the original shake-deflate design using standard filter bags to the reverse-air with sonic horns using membrane bags. An analysis of the cost of the upgrades and subsequent savings for each step will be included.

Commentary by Dr. Valentin Fuster
2004;():205-207. doi:10.1115/NAWTEC12-2225.

Waste to Energy facilities in the U.S. collectively spend over $20 million per year on lime for flue gas treatment. Individually, most plants spend between $300,000 and $1 million per year on lime. This expense is often the plant’s largest for a consumable material and is expected to increase as emission limits become more stringent.

Commentary by Dr. Valentin Fuster
2004;():209-227. doi:10.1115/NAWTEC12-2226.

The application of mass burn waste-to-energy (WTE) plants is becoming more popular in Asia, not just for proper disposal of municipal solid waste (MSW) like most plants in the western world do but stretched by many Asian plants to co-incinerate non-hazardous industrial waste (IW) in order to maximize the use of the plant facilities, hence to save costs from building facilities specifically for treating IW. As the plants are designed with conventional considerations practiced in the western world and the original designs are not oriented towards co-incinerating large percentages of IW, plant operators frequently face challenges such as unstable combustion quality, frequent boiler tube rupture amplified by co-incineration, inadequacy of the conventional control systems and other facilities to handle the co-incineration application. One co-incineration WTE plant in Taiwan is used as an example to illustrate the significance of these challenges, some measures taken to abate the problems and the cost impacts. Suggestions are also provided for technical management of co-incineration plants.

Commentary by Dr. Valentin Fuster
2004;():229-240. doi:10.1115/NAWTEC12-2227.

This paper constitutes a follow-up on a presentation at NAWTEC 10 (2001) [1]. It contains novel insights regarding the operation of the Seghers Boiler Prism and its effectiveness as a primary measure against high temperature boiler corrosion in WtE plants. Starting from the currently available fundamental understanding on high temperature corrosion and the main features of the Boiler Prism, the operation as a primary measure is explained. Since the previous presentation, three additional Boiler Prisms were successfully commissioned as a retrofit at a large WtE facility (3 × 705tons/day at 4,700BTU/lb; 110tons/hour steam at 1,450psi, 750°F) in the Netherlands. Together with the previously installed prisms, this brings the combined operational experience from all trains to more than 15 years. The main data and experience of the retrofit project in the Netherlands are discussed and results regarding the performance of the prism are presented in detail. The latter are based both on existing process monitors as well as dedicated measurement campaigns and include: • temperature and oxygen distribution in the 1st radiation pass, • feedback on corrosion rates, • influence on the combustion quality, and • impact on the effectiveness of the mechanical cleaning equipment. The results confirm the effectiveness of the prism as a primary measure against high temperature boiler corrosion and highlight the additional operational benefits.

Commentary by Dr. Valentin Fuster
2004;():241-250. doi:10.1115/NAWTEC12-2228.

The eco/Technologies Sludge Recycling System (eco/Tech SRS) was introduced at NAWTEC 10 and has now been operating commercially for two years at the Pioneer Valley Resource Recovery Facility (PVRRF), located in Agawam, Massachusetts. A second system will be installed at the Pittsfield Resource Recovery Facility (PRRF), located in Pittsfield, Massachusetts, in 2004 and EnergyAnswers is now marketing the system to other power plant owners. Presented in this paper is an overview of: • Operating and maintenance history at PVRRF; • Market conditions and challenges; • Air emissions results; • Design enhancements planned for PRRF. The data presented support the potential for waste-to-energy plants, and by extension all solid fuel power plants, to benefit from additional revenue streams while using a waste product to achieve air emissions reductions.

Topics: Recycling
Commentary by Dr. Valentin Fuster
2004;():251-258. doi:10.1115/NAWTEC12-2229.

Waste management in the United States presently has the following major three dimensions: Sanitary landfills, recycling, waste to energy predominantly based on the technologies of mass bum technology or refuse derived fuel. These three dimensions have undergone significant evolution during the past three decades. The design of sanitary landfills has evolved to include environmental protection features such as bottom liners, leachate collection systems and landfill gas management systems. Material recycling programs, many based on materials recycling facilities, have become more prevalent. Approximately 100 operating waste to energy facilities (“Facilities”) now exist in the United States. Improvements in the air pollution control systems incorporated in the Facilities have significantly lowered their air emissions. A fourth dimension, waste gasification technology, is evolving as a viable component of a waste management system and the hydrogen energy economy.

Commentary by Dr. Valentin Fuster
2004;():259-264. doi:10.1115/NAWTEC12-2230.

Multicomponent Infrared Gas analyzers have been a workhorse as Continuous Emissions Monitoring Systems (CEMS) in the waste-to-energy (WTE) application for the past two decades. It is the technique of choice for many facilities. With obsolescence for electronics, instrumentation and data acquisition systems (DAS) averaging less than 10 years, the earlier multicomponent CEMS are being upgraded to what is now a third generation of that technology. This paper describes the evolution of the three generations of multicomponent CEMS. The evaluation of this technology in the WTE application encompasses the operating histories of nearly two dozen facilities demonstrating compliance with this type of CEMS. Specific details explaining the sampling systems, analyzer optics & controls, interface and communication with plant distributed control systems, and DAS systems are presented. Relative accuracy test audit (RATA) results, CEMS availability histories and annual maintenance costs are reviewed presenting a unique insight into both initial capital costs and operating costs. Actual annual man-hour totals for preventive maintenance (PM), unscheduled maintenance, and annual consumable parts costs are provided. Advances in computer capabilities have provided an opportunity for CEMS functions to not only become more comprehensive but also more robust. Key among these advances is the ability for factory-support services to be provided not only for the software platform but now even down to the basic auditing parameters of the analyzers themselves. Third generation CEMS now feature remote access of the analyzers from the instrumentation repair shop, the vendor’s factory or from the company’s technical service center.

Commentary by Dr. Valentin Fuster
2004;():265-271. doi:10.1115/NAWTEC12-2231.

A large fraction of the municipal solid wastes (MSW) stream in the U.S. comprises of natural organic compounds (i.e., food and plant wastes) with high moisture content and low heating value. While these properties are undesirable during the combustion of MSW in waste-to-energy (WTE) plants, they are required for anaerobic digestion (AD). During AD, methane gas is produced that can be captured and used for energy generation. The required long residence times limit the throughput of an AD plant but further development may result in increasing the rates of bioreactions. This paper introduces current AD practices and identifies possible synergies between AD and WTE. It is suggested that co-siting of WTE and AD facilities may result in mutual benefits.

Topics: Waste-to-energy
Commentary by Dr. Valentin Fuster
2004;():273-282. doi:10.1115/NAWTEC12-2232.

Mixing of the highly non-homogeneous municipal solid wastes (MSW) on the traveling grate of mass-burn combustion chambers assists the combustion process in waste-to-energy (WTE) facilities. A matrix-based Markov chain model was developed to simulate particle flow and mixing as the solid waste particles travel over a reverse acting Martin grate. The model was used to project the pathway of a solid waste particle over a time series, in the bottom layer of the bed that is in contact with the bars of the grate. Further analytical and experimental work is planned in order to develop this model to a useful tool for designing future moving grate systems and increasing the combustion efficiency of existing WTEs.

Commentary by Dr. Valentin Fuster

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