For several US communities municipal waste combustor (MWC) ash recycling has been a commercial reality for almost a decade with over 1 million tons processed and beneficially used to date. Yet, despite the successes to date a recent report by the Integrated Waste Services Association shows less than 5% of the 7.5 million tons of ash generated in the US is recycled and beneficially used [1]. The technological, scientific and myriad of commercial successes categorically demonstrate the feasibility of ash recycling. The next step is for communities, regulatory agencies, transportation departments, and customers to partner with businesses to recycle their ash stream in an economically and environmentally sound manner. An example of this “ partnering for progress ” is the focus of this paper. The ash recycling partnership described in this paper was presented the Pennsylvania Governor’s Award for Environmental Excellence in 1999. Proving that Partnering is a win-win situation for businesses, communities and the environment.

County State Aid Highway (CSAH) 13, located in Polk County Minnesota, was to be paved with 2.25 miles of new bituminous in October of 2000. Prior to the end of the 2000 construction season, a portion of one lane of the base course was installed, with the remainder to be completed in spring of 2001. The bituminous was amended with ash generated at the municipal solid waste combustor located in Fosston Minnesota. One third of the road was to be paved with traditional bituminous, one third was to be paved with bituminous in which a portion of the aggregate was replaced with “new” ash and one third was to be paved with bituminous in which a portion of the aggregate was replaced with “old” ash. “New” combustor ash is ash generated after the installation of an up-front materials recovery facility (MRF) and “old” combustor ash is ash generated before the installation of the MRF. Ash-amended bituminous was to be used in the base course and binder course of the pavement profile. Significant environmental and structural testing was performed prior to construction. Environmental and structural testing was also performed simultaneously with the construction process. Environmental testing completed in 2000 included: analysis of stack emissions from the bituminous plant, evaluation of breathing zone particulates at the bituminous plant, and analysis of surface water runoff from the ash-amended bituminous. Structural testing included trial mix design parameters. The road was also instrumented to collect water that may infiltrate through the ash-amended bituminous. Environmental testing to be completed in 2001 includes: evaluation of impacts to soils adjacent to the roadway and evaluation of infiltration water collected in the under-pavement collectors. Post-construction pavement testing is also to be completed in 2001. This paper presents the initial results of environmental and structural testing as well as construction issues.

The SEMASS Resource Recovery Facility (SEMASS) is a processed refuse fuel (PRF) waste-to-energy plant serving much of Southeastern Massachusetts. Units 1 and 2 at the plant were designed with spray dryer absorbers (SDAs) and electrostatic precipitators (ESPs). A review of historical data from the plant indicated that in order to comply with the Environmental Protection Agency’s Municipal Waste Combustor (MWC) Rule (40 CFR Part 60, Subpart Cb), which is known as the Maximum Achievable Control Technology (MACT), improved emission performance would be required from the flue gas cleaning system on Units 1 and 2. A pilot test program was conducted which led to the installation of COHPAC, or CO mpact H ybrid PA rticulate C ollector units (i.e. flue gas polishing devices) downstream of the ESPs on these two combustion trains. The COHPAC units were successfully started up in June, 2000. In addition to these modifications, it was determined that further control of mercury emissions would be required. A system to inject powdered activated carbon into the flue gas was added to the plant. This paper describes that carbon injection system. A comparison between test data obtained at SEMASS is made with predictions based upon the EPA testing at the Ogden Martin Systems of Stanislaus, Inc. Municipal Waste Combustor Facility near Crows Landing, California and the EPA testing at the Camden County Municipal Waste Combustor in Camden, New Jersey. These are waste-to-energy plants, the former utilizing an SDA and a baghouse while the latter contains an SDA followed by an ESP. In addition, the effect of carbon injection location upon mercury reduction was investigated. The results of that study are also included.

The size and shape of New York City municipal solid waste (NYCMSW) and combustion residues (ashes) are numerically analyzed in order to investigate the size reduction of particles on the grate of a waste-to-energy (WTE) combustion chamber. It is also necessary for designing a new combustion chamber, due to the heterogeneous MSW particles. About 360 MSW particles for this study were sampled in the black bags collected in residential areas at five boroughs of New York City. Also about 210 ash particles from a WTE combustion chamber were sampled. Length, breadth, perimeter and area of each MSW and ash particle are measured by means of image analysis that is more accurate than sieve analysis. Based on the image analysis, the particle size distributions (PSiD) and particle shape distributions (PShD) of MSW and residues were created. The mean size of NYCMSW was found to be 12.8cm and standard deviation of the MSW PSiD to be 6.4. Also mean size and standard deviation of the ash PSiD to be 2.4cm and 0.5889, respectively. Also Three types of shape factors (aspect ratio, roundness and sphericity) are used for creating 3 PShDs (aspect-ratio distributions, roundness distributions and sphericity distributions). Based on the similarity of the particle shapes quantified as these shape factors, the particles of MSW and residues are divided into 9 clusters by means of cluster analysis. This cluster analysis showed categorized characteristics of particle shapes that can be used for predicting surface areas of particles and mobility of particles in MSW bed on the traveling grate, both of which are major parameters for simulating combustion process in WTE systems.

ASME PTC 34 is a test procedure for determining the thermal capacity and thermal efficiency of systems (typically boilers) combusting waste fuels (typically Municipal Solid Waste - MSW) and for determining the higher heating value (HHV) of those waste fuels. The basis of the procedure is more commonly known as the “boiler-as-a-calorimeter” method. The need for PTC 34 arose from the difficulties in obtaining representative samples and accurate fuel analyses using traditional laboratory methods such as a “bomb calorimeter”. Unsuccessful attempts were made to come up with a larger “bomb calorimeter”, so a committee was formed to create PTC 34 which was published in 2007. ASME PTC 34 is firmly based on the widely accepted boiler test code, ASME PTC 4 – “Fired Steam Generators”, but has several different challenges in having to measure the relatively difficult parameters of flue gas flow and moisture and fuel and ash quantities. As a result, the uncertainty of PTC 34 is higher. However, the philosophy of correcting results to standard, contract or reference fuel analysis is the same in PTC 4 and PTC 34. So, an industry approved Code for acceptance testing is available to the Energy-from-Waste industry. ASME PTC 34 can be used in several ways depending on the analysis time period. It can be used for typical short-term, i.e. 8-hour, performance or acceptance tests, again with the ability to correct to reference fuel analyses. Alternatively, multiple “samples” of fuel HHV can be obtained using PTC 34. With the test data and HHV results, accurate correlations can then be generated to be able to make adjustments for varying fuel conditions in longer term, i.e. 7-day, throughput capacity testing. The 8-hour HHV determinations can also be used to validate or even calibrate correlations used over the life of a waste combustor as operating parameters stray from their normal ranges. Taken to the extreme, PTC 34 can be used as a basis for near-real-time monitoring of fuel quality or possibly combustion control. Recent developments of laser-based flue gas moisture instruments and the economizer heat balance method for determining flue gas flow make this leap possible. The goals of this paper are to make the industry more aware of ASME PTC 34 and the guidance it contains on making the difficult measurements, to promote its use as a standard in the industry and to instill confidence in the time-tested and accepted process of making corrections to test results for off-design fuel characteristics.

The EPA defines a small municipal waste combustor (MWC) Class II facility as having an aggregate plant capacity of 250 tons per day (TPD) or less. Some commercial Waste-to-Energy (WTE) operators consider that there is an economy of scale required that is much greater. So what about small facilities? Can public entities or private companies make the economics work? This paper will offer a status of existing small facilities, available combustion technologies and identify known planned expansions or new facilities. The paper will feature one such facility with an interesting past and a bright future including plans for expansion: the Perham Resource Recovery Facility in Perham, Minnesota. This cogeneration facility plans to increase its capacity from 112 TPD to 200 TPD along with adding upfront processing to improve fuel quality.

When the initial generation of U.S. municipal waste combustor (WTE) facilities was developed during the 1980s and early 1990s, the only tools that were included in the service agreement to deal with a contract operator that was not meeting the contract terms was either dispute resolution or default and termination. After 20 years of administering these service agreements, those two provisions have proved inadequate for publicly owned WTE facilities particularly as it relates to ongoing maintenance. Additional provisions have recently been developed and incorporated into the next generation of service agreements to address this need. Contract operators of publicly owned WTE facilities typically focus their attention on facility performance and less on long-term facility asset preservation, especially for the portions of the facility that are not critical to production. If a contract operator is meeting all of its performance guarantees, but is falling behind on the general upkeep of facility buildings and/or infrastructure, owners will likely not invest the time and money in dispute resolution to try to get those items repaired. Additionally, neglect of those items does not rise to the level that the operator can be defaulted and terminated. As a result, conditions generally deteriorate to the point where the relations between the owner and contract operator are adversely affected. If the deferral of maintenance continues until the end of the service agreement term, the public owner will be faced with added capital costs and/or increased operating costs under a new service agreement for items that he already paid the previous operator for. This paper describes the new contractual provisions that have been developed in the latest generation of service agreements aimed at helping public owners of WTE facilities resolve these types of problems at minimal cost. Instead of only having the “nuclear weapons” (e.g., formal—and expensive—dispute resolution or default and termination), a series of mechanisms have been developed that provide owners with some “small arms weapons” to assure that the timely and proper maintenance is performed on all aspects of the WTE facility, thereby assuring its long-term preservation. This paper also sets forth case studies of three WTE facilities in the Tampa Bay, Florida area where these latest contractual provisions are being implemented and the results to date.

This presentation will provide a historical perspective on the development of waste-to-energy (WTE) and conversion technologies in the 1970s and 1980s. During this time period, U.S. EPA provided grant assistance to a variety of projects and technologies including refuse derived fuel (RDF) production, RDF combustion, pyrolysis, gasification and anaerobic digestion. This presentation will also provide the latest, up-to-date information about WTE and alternative technologies, including data on costs, and current status of projects developing across North America as they exist in 2010. It will provide a review of WTE technologies as an element of integrated solid waste management systems and highlight some of the advances which have been moved into production units to make WTE environmentally friendly. It will also include a brief look at plants worldwide, followed with a focus on facilities, technologies and companies operating in the U.S. Specific examples of technologies and associated facilities will include: –Mass Burn; –Modular; –RDF - Processing & Combustion; –RDF - Processing Only; –RDF - Combustion Only. Municipal waste combustors are regulated under the federal Clean Air Act (CAA), originally passed by Congress in 1963 and amended in 1967, 1970, 1977, 1990 and 1995 and 1998. The U.S. EPA may implement and enforce the requirements or may delegate such authority to state or local regulatory agencies. The CAA places emissions limits on new municipal waste combustors. In addition, the 1995 amendments to the Clean Air Act (CAA) were developed to control the emissions of dioxins, mercury, hydrogen chloride and particulate matter. By modifications in the burning process and the use of activated carbon injection in the air pollution control system, dioxins and mercury, as well as hydrocarbons and other constituents, have effectively been removed from the gas stream. The presentation will also review the companies offering WTE in the form of alternative technologies being promoted and considered in the U.S., and several recent and current procurements will be reviewed. GBB tracks over 150 different companies offering technologies, facilities and services whose developmental stages range from engineering drawings and laboratory models to full-scale operating prototypes. The presentation will provide an overview of these systems and their status. Implementation of new WTE projects — whatever technology is selected — will involve local governments in the process because MSW management is a local responsibility. Implementation will involve risks for local government and any private entities involved. A comprehensive review of the risks and challenges associated with implementing various technologies will be provided. The presentation will conclude with key elements to keep in mind when implementing WTE and/or conversion technologies. The last new MSW-processing WTE facility constructed in the U.S. commenced operations in 1996. Since that time, no new greenfield commercial plant has been implemented. In the past few years, however, interest in WTE and waste conversion has begun to grow, again. This renewed interest in waste processing technologies is due to several factors: successful CAA retrofits, proven WTE track record, increasing cost of fossil fuels, growing interest in renewable energy, concern of greenhouse gases, reversal of the Carbone Supreme Court Case, and the change in U.S. EPA’s hierarchy, which now includes WTE. Since 2004, several municipalities commissioned reports in order to evaluate new and emerging waste management technologies and approaches. These will be summarized. With the passage of the American Recovery and Reinvestment Act of 2009, the U.S. DOE has been working to advance innovative green energy technologies, which can be applied to MSW as well as other bio-feedstocks. DOE has made a number of grant awards to projects where MSW is used as a feedstock. This presentation will summarize the status of these projects and discuss how they should be viewed when considering new projects. The presentation will also outline policies for governments to consider when considering recycling goals with WTE. This review will be done in the context of environmental and energy considerations as well as public policy considerations. Comments will be included regarding current legislation and regulations, specifically for greenhouse gas emissions, being considered by the U.S. or state governments. The presentation will provide participants with: –A historical reference for experiences with WTE/alternative technologies in the U.S. in the 1970s and 1980s; –Latest information on the state of WTE/alternative technologies in the U.S., including their environmental performance; –A global understanding of current technologies and trends; –Understanding of the risks and challenges associated with implementing various technologies; –Understanding the key elements to keep in mind when implementing WTE; –Suggested policy for recycling and WTE to co-exist as components of a local solid waste system; and –Comments about current legislation being considered by the U.S. and state governments.

The range of fuels fed to waste incineration plants extends from well-sorted domestic refuse through mixed waste fractions to fuel mixtures that may additionally contain various types of hazardous waste and biomass. This diversity results in a great number of fuel and ash compositions. Among these are fuels with a high calorific value as well as with a low calorific value and simple fuel ashes just as highly problematic fuel ashes. The latter can lead to increased slagging in the combustion chamber and fouling in the open passes of waste incineration plants as well as accelerated corrosion. The plant operator is consequently faced with considerable challenges associated with unscheduled boiler downtime and production losses. The paper describes how fuel specific process know-how is applied in combination with fully automated, efficient onload boiler cleaning systems to control the slagging issues. The paper describes a system which utilizes water as the cleaning medium. The system allows the targeted cleaning of waste incinerators during operation. This paper points out challenges faced by plant operators and suppliers of boiler cleaning technology caused by the heterogeneous fuel composition, and describes in well monitored case studies how these challenges can be successfully met.

Flow, mixing, and, size segregation of Municipal Solid Waste (MSW) particles on the traveling grate of a mass-burn waste-to-energy (WTE) combustion chamber is analyzed for understanding those parameters that control the combustion processes and for designing the chamber. In order to quantify these phenomena, a full-scale physical model of the reverse acting grate was built and used for investigating the effects of the motion of the reverse acting grate under a MSW packed bed with tracer particles ranging from 6 – 22 cm in diameter. Based on these experimental data, a stochastic model of MSW particle within the packed bed on a traveling grate was applied for simulating the MSW particle behavior. The result shows that the motion of the traveling grate, whose speed ranged from 15 to 90 reciprocations/hour, increases the mean residence time of small and medium particles by 68% and 8%, respectively, while decreasing the mean residence time of large particles by 17%. This is because of size segregation of particles known as the Brazil Nut Effect. When the ratio of particle diameter to the height of moving bar, d/h, increases from 0.46 to 1.69, the mixing diffusion coefficient, De at 60/hour., decreases from 96 to 38.4. This indicates that the height of the moving bars should be greater than the diameter of targeted particles.

The incorporation of municipal solid waste combustor (MWC) ash into bituminous pavements has been investigated in the United States since the middle 1970s. Thus far, most, if not all of these projects, have attempted to answer the questions: Is it safe? Is it feasible? Or does it provide an acceptable product? Polk County Solid Waste located in Northwest Minnesota has now completed three Demonstration Research Projects (DRP) utilizing ash from its municipal solid waste combustor as a partial replacement of aggregate in asphalt road paving projects. The results of these projects show no negative environmental or worker safety issues, and demonstrate improved structural performance and greater flexibility from the ash-amended asphalt as compared to conventional asphalt. Polk County has submitted an application to the Minnesota Pollution Control Agency (MPCA) to obtain a Case-Specific Beneficial Use Determination (CSBUD), which would allow for continued use of ash in road paving projects without prior MPCA approval. However, concerns from the MPCA Air Quality Division regarding a slight increase in mercury emissions during ash amended asphalt production has resulted in a delay in receiving the CSBUD. Polk County decided to take a different approach. In January 2008, Polk submitted and received approval for their fourth ash utilization DRP. This DRP differs from the first three in that the ash will be used as a component in the Class 5 gravel materials to be used for a Polk County Highway Department road rebuilding project. The project involves a 7.5 mile section of County State Aid Highway (CSAH) 41, which conveniently is located about 10 miles south of the Polk County Landfill, where the ash is stored. The CSAH 41 project includes the complete rebuilding and widening of an existing 7.5 mile paved road section. Ash amended Class 5 gravel would be used in the base course under the asphalt paving, and also in the widening and shouldering sections of the road. The top 2 inches of the widening and shouldering areas would be covered with virgin Class 5 and top soil, so that all ash amended materials would be encapsulated. This has been the procedure followed in previous projects. No ash will be used in the asphalt mix for this project. This paper discusses production, cost, performance and environmental issues associated with this 2008 demonstration research project.

The Air Force Research Laboratory, Airbase Technologies Division (AFRL/RXQ) is engineering and evaluating the Transportable Waste-to-Energy System (TWES). This trailer mounted system will convert military base waste and biomass waste streams to useful heat and power. The Department of Energy (DOE) Federal Energy Management Program (FEMP) is a TWES funding partner. The first stage of the project is a suspension-type combustor (furnace). The furnace has been built and tested. A key feature of the furnace system is its unique patented combustion coil design. The design is intended to maximize ablative heat transfer by increasing particle residence time near a radiant ignition source. The innovative features of the design are targeted at ensuring that the system can be highly fuel-flexible to convert a variety of biomass and other waste streams to energy while demonstrating very low emissions. In 2008, the unit underwent two days of emissions stack testing using established Environmental Protection Agency (EPA) testing protocols. During the testing, extensive real-time data were also collected. This paper presents the data and corresponding analysis of the recent emissions testing performed while utilizing dry wood chips as a control fuel. Detailed emission comparisons are presented using publicly available information from commercial units and from a similarly sized experimental system for small biomass combustion. Key combustion efficiency factors, such as carbon monoxide emissions and nitrogen oxide emissions are presented. The authors also provide commentary on the results for next generation units and the use of this mode of energy conversion for small scale systems.

The dominant waste-to-energy technology is combustion of “as-received” municipal solid wastes (MSW) on a moving grate. By far, the largest cost item in the operation of such plants is the repayment of the initial capital investment of $600 to $750 per annual metric ton of capacity which results in capital charges of $60–75 per ton of MSW processed. On the average, such plants generate about 650 kWh of electricity per metric ton of MSW combusted. Therefore, on the basis of 8,000 hours of operation per year (90% availability), the capital investment in WTE facilities ranges from $7,500 to $9,000 per kW of electric capacity. This number is three times higher than the present cost of installing coal-fired capacity (about $2,500 per kW). Of course, it is understood that WTE plants serve two purposes, environmental disposal of solid wastes and generation of electricity; in fact, most WTE plants would not exist if the fuel (i.e. the MSW) had to be paid for, as in the case of coal, instead of being a source of revenue, in the form of gate fees. However, the question remains as to why WTE plants are much more costly to build, per kWh of electricity generated, than coal-fired plants, even when the coal supply is lignite of calorific value close to that of MSW (about 10 MJ/kg). This study intends to examine the possible contributing causes, one by one, in the hope that the results may lead to the design of less costly WTE plants. Some of the factors to be examined are: Feed-stock handling; heat generation rate per unit volume of combustion chamber; heat transfer rate per unit area of boiler surfaces; % excess air and, therefore, volume of gas to be treated in Air Pollution per kW of electricity; differences in gas composition and high temperature corrosion in boiler that limit steam temperature and pressure and thus thermal efficiency; cost of APC (air pollution control) system because of the need to remove volatile metals and dioxin/furans from the process gas; and the handling of a relatively large amount of ash. In seeking the answers to the above questions, the study also compares the operational performance characteristics and engineering design of various existing WTE plants. This study is at its very beginning and it is presented at NAWTEC 17 in the hope of generating useful discussion that may lead to significant improvements in the design of future WTE facilities. The WTEs built in the U.S. until 1995 were designed for efficient and environmentally benign disposal of MSW, with energy recovery being a secondary consideration. There have been three principal changes since then: (a) the capital cost of WTEs, per daily ton of capacity has doubled and in some cases nearly tripled, (b) energy recovery per unit of carbon dioxide emitted has become an important consideration, and (c) the price of renewable electricity has increased appreciably. All these three factors point to the need for future WTEs to become more compact, less costly to build, and more energy-efficient. It is believed that this can be done by combining developments that have already been tested and proven individually, such as shredding of the MSW, higher combustion rate per unit surface area of the grate, oxygen enrichment, flue gas recirculation and improved mixing in the combustion chamber, superior alloys used for superheaters, and steam reheating between the high-pressure and low-pressure sections of the steam turbine. For example, oxygen enrichment is practiced at the Arnoldstein, Austria, WTE where parts of the primary air stream are enriched between 23% and 31% oxygen; steam reheating has been proven at the Waste Fired Power Plant of AEB Amsterdam where electricity production for the grid has been increased to over 800 kWh per ton MSW.

In September of 2007, a new 636TPD Municipal Waste Combustor was brought on line at the Lee County WTE Facility in Fort Myers, FL operated by Covanta Energy. This unit was the first new Waste to Energy unit built in the United States in a number of years and included a lower permitted daily average NOx emissions requirement of 110ppm @ 7%O2 while maintaining ammonia slip to less than 10ppm. To meet this new stringent NOx emissions requirement, the boiler was designed with advanced combustion controls including Flue Gas Recirculation combined with a urea based Selective Non-Catalytic Reduction Process to provide a combined NOx reduction of approximately 70% while maintaining the required ammonia slip. The SNCR System provided by Fuel Tech was designed with 3 levels of seven wall injectors installed in the upper furnace. Both boiler load and Furnace Gas Temperature were used as a feed forward control with the CEM NOx signal as a feed back to automatically select the injector levels and reagent feed rates to maintain the targeted NOx while also maintaining ammonia slip control. This paper will outline the design considerations, the details of the process and the operation of the systems on this unit.

Over the last two and a half years, Covanta Energy, working with their technology partner, Martin GmbH of Germany, has developed and commercialized a new technology for reducing NO x emissions from Energy from Waste (EfW) facilities. NO x levels below 60 ppm (7% O2) have been reliably achieved, which is a reduction of 70% below the current EPA standard and typical levels of today’s EfW facilities in the United States. This technology represents a significant step forward in NO x control for the EfW industry. The technology, known as VLN™, employs a unique combustion system design, which in addition to the conventional primary and secondary air streams, also features a new internal stream of “VLN™-gas,” which is drawn from the combustor and re-injected into the furnace. The gas flow distribution between the primary and secondary air, as well as the VLN™-gas, is controlled to yield the optimal flue gas composition and furnace temperature profile to minimize NO x formation and optimize combustion. The VLN™ process is combined with conventional, aqueous ammonia SNCR technology to achieve the superior NO x performance. The SNCR control system is also integrated with the VLN™ combustion controls to maximize NO x reduction and minimize ammonia slip. A simplified version of the process, known as LN™, was also developed and demonstrated for retrofit applications. In the LN™ process, air is used instead of the internal VLN™ gas. The total air flow requirement is higher than in the VLN™ process, but unchanged compared to conventional systems, minimizing the impact on the existing boiler performance and making it ideal for retrofit applications. Covanta first demonstrated the new VLN™ and LN™ processes at their Bristol, Connecticut facility. One of Bristol’s 325 TPD units was retrofitted in April of 2006 to enable commercial scale testing of both the VLN™ and LN™ processes. Since installing and starting up the new system, Bristol has operated in both VLN™ and LN™ modes for extended periods, totaling more than one year of operation at NO x levels at or below 60 ppm (7% O2). The system is still in place today and being evaluated for permanent operation. Based on the success of the Bristol program, Covanta installed LN™ NO x control systems in a number of other existing units in 2007 and 2008 (total MSW capacity of over 5000 TPD), and is planning more installations in 2009. All of these retrofits utilize the Covanta LN™ system to minimize any impacts on existing boiler performance by maintaining existing excess air levels. Going forward, Covanta is making the LN™ technology available to its existing client base and is working with interested facilities to complete the necessary engineering and design modifications for retrofit of this innovative technology. For new grassroots facilities, Covanta is offering the VLN™ system with SNCR as its standard design for NO x control. An additional feature, particular to VLN™, is the reduced total combustion air requirement, which results in improved boiler efficiency. This translates into increased energy recovery per ton of waste processed. In addition to introducing the VLN™ and LN™ processes, this paper will provide an overview of the Bristol development and demonstration project. NO x and NH 3 slip data from Bristol will be presented, illustrating the extended operating experience that has been established on the system. Other operating advantages of the new technology will also be discussed, along with lessons learned during the start-up and initial operating periods. The VLN™ technology has been demonsrated to decrease NO x emissions to levels well below any yet seen to date with SNCR alone and is comparable to SCR-catalytic systems. The result is a significant improvement in NO x control for much less upfront capital cost and lower overall operating and maintenance costs. VLN™ also also goes hand in hand with higher energy efficiency, whereas SCR systems lower energy efficiency due to an increased pressure drop and the need for flue gas reheat. The commercialization of the VLN™ and LN™ processes represents a significant step forward in the reduction of NO x emissions from EfW facilities.

Olmsted County is currently expanding their existing waste-to-energy facility in Rochester, Minnesota to add a third mass burn waste combustor. The new unit will have a capacity of 200 TPD, effectively doubling the size of the existing capacity. This paper will discuss some of the unique aspects of this project and review the current status. Some of the interesting and unique features to be discussed include: 1. Environmental Permitting – The county decided to do a voluntary EIS. 2. Project approach – The county is using a Construction Manager at Risk approach for construction of the facility. 3. Engineering – The engineering scope includes several separate procurements of major equipment packages, balance of plant design and several auxiliary projects related to the ‘utility’ system. 4. Operator Collaboration – Olmsted County is one of a few public owners that operate their facility. Their knowledge of the existing facility and of operating a mass burn facility has been used extensively in the planning and design of the new unit.

Municipal solid waste (MSW) management is internationally recognized for its potential to be both a source and mitigation technology for greenhouse gas (GHG) emissions. Historically, GHG emission estimates have relied upon quantitative knowledge of various MSW components and their carbon contents, information normally presented in waste characterization studies. Aside from errors associated with such studies, existing data do not reflect changes over time or from location to location and are therefore limited in their utility for estimating GHG emissions and mitigation due to proposed projects. This paper presents an alternative approach to estimate GHG emissions and mitigation using the concept of a carbon balance, where key carbon quantities are determined from operational measurements at modern municipal waste combustors (MWCs).

This paper assesses the incineration capacity requirement of the Province of Turin through a detailed analysis of the mass streams and the properties of residual Municipal Solid Waste (MSW). Historical data series were elaborated to study the trend evolution of household generation and separate collection. Residual MSW material compositions were calculated for each year over an observed period and for planned scenarios. A waste properties model was applied to calculate the residual MSW chemical composition and the LHV. The analysis allows conclusions to be drawn about the design of the planned waste-to-energy plant and to estimate the required size and technology to be used. The results show that the use of grate furnace combustor appears to be more suitable than fluidized bed.

Two of Energy Answers Corporation’s (EnergyAnswers) waste-to-energy (WTE) facilities utilize mass burn stepped hearth refractory combustors. Three 120 ton per day (TPD) units are located at the Pittsfield (MA) Resource Recovery Facility and three 136 TPD units are at the Pioneer Valley Resource Recovery Facility in Agawam, MA. EnergyAnswers has over 20 years operating experience with these mass burn units which are known for their rugged construction and dependable operation. Over the past several years, EnergyAnswers operating personnel have developed and installed numerous improvements which have reduced residual carbon in the ash, lowered operating and maintenance (O&M) costs, and increased steam generation and throughput. The following highlights the numerous improvements that have resulted in a new generation of mass burn combustor called Pioneer Plus™: • Improved tracking and alignment of the ash transfer ram carriages for reduced air infiltration and jamming, • Utilization of poured and sprayed refractories for lower O&M costs, • Improved control of under-fire air to improve burn out and steam rate while maintaining throughput, • Better sealing to reduce air in-leakage and ash accumulation. The above improvements have been implemented on several of the combustors at the EnergyAnswers facilities. Additional improvements have been identified and will be incorporated into the design of new Pioneer Plus™ plants in the coming years.

The Lee County Expansion Project is a 636 ton per day Municipal Waste Combustor (MWC) in late stages of construction/startup, located in Ft. Myers, FL. The new unit complements the existing 1200 ton per day two-unit facility owned by the County and operated by Covanta Lee, Inc., which has been in service since 1994. The new unit is the first MWC permitted and constructed under the EPA’s New Source Performance Standards (NSPS) since they were promulgated in the 1990’s. This paper will describe the basic contractual arrangements, permitting, design and construction features, and overall costs for the expansion project.