Experience With Weld Overlay and Solid Alloy Tubing Materials in Waste to Energy Plants

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.

Ash Recycling: Just a Dream?

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].

Accrediting Greenhouse Gas Credits for Marketing: The Saugus Experience

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.

Use of Multicomponent Infrared Gas Analyzers at Waste-to-Energy Facilities

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.

Seghers Boiler Prism: A Proven Primary Measure Against High Temperature Boiler Corrosion

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.

Improvement in Operating and Maintenance Cost With a Fabric Filter Conversion Using Polytetrafluoroethylene (PTFE) Membrane Filter Media

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.

SUWIC Innovations in Thermal Waste to Energy Technologies

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.

Technical Challenges and Abatements of a Mass Burn Waste-to-Energy Plant Co-Incinerating Municipal Solid Waste and Industrial Waste

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.

Lime Usage Reduction at the Delaware Valley Resource Recovery Facility

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.

Simulation and Validation of a Mass Burn WTE Boiler Using CFD Modeling

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.