The Lee County WTE Expansion Project Building a New WTE Unit in the 21st Century

Transcription

1 15th North American Waste to Energy Conference May May 21-23, 2007, Miami, Florida USA NAWTEC The Lee County WTE Expansion Project Building a New WTE Unit in the 21st Century Donald J. Castro, P.E. Vice President HDR Engineering, Inc Lindsey J. Sampson, P.E. Director of Solid Waste Division Lee County, Florida 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 twounit facility owned by the County and operated by Covanta Lee, Inc., which has been in service since 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. Background Lee County, FL, located in the fast growing Southwest Florida sun coast area, has been experiencing compound growth in the high single digit range for over 5 years. Despite aggressive recycling programs, the unprecedented growth in population and resultant increase in waste quantities led the County to seek new waste disposal capacity in the early 2000's. The heart of the County's integrated waste recycling and disposal operations are co-located at the site of the existing 1200 ton per day waste to energy facility. The site complex also includes a Material Recovery Facility, yard waste processing facility, and a MSW transfer station. Bypass waste quantities are disposed at the County's landfill (the Lee/Hendry Landfill), along with residue from the existing MWC units. Following due diligence investigations of the options available for providing additional capacity, the County chose to expand the existing WTE facility by adding a third combustion train and a second turbinegenerator. It should be noted that the original facility was built with future expansion capability in mind, and several key elements were already in place. These included a concrete stack with space available for a third flue, and tipping floor, waste pit and crane capacity originally sized to be capable of supporting a third unit. The decision to proceed with the expansion was made by the Board of County Commissioners in early 2004 after the Florida DEP issued the PSD Permit, which locked in certain design choices. Amongst these was the decision to add a third Martin Stoker, with technology licensed by Covanta Energy, Inc. from Martin GMBH of Munich, Germany. The decision to utilize the Martin mass burn grate system was made following investigation of modem 97

2 waste to energy practice worldwide, with an emphasis on European experience. During this time frame, Covanta Energy was under reorganization following their Chapter 11 bankruptcy proceedings initiated in As will be seen, Covanta's bankruptcy status at that time, including future uncertainties regarding the outcome, led the County to make certain decisions regarding its strategy for implementing the project. Permitting As the first MWC unit to be permitted under the NSPS, the permitting process was both lengthy and complex. The key elements of the permit are listed in Table 1, including the permit limits for the existing Units 1 and 2, for comparison with the new Unit 3. Of all of the parameters of interest, the NOx limits presented unique challenges, and resulted in hardware configurations that differ from most, if not all, domestic MWC's currently in service. With a Florida Department of Environmental Protection (FDEP) imposed 12-month rolling average annual NOx limit of 110 ppm 1, the County was faced with a limit that was considerably more restrictive than the NSPS limit of 150 ppm. In addition, an ammonia slip limitation of 30 ppm was part of the permitted conditions. Given these aggressive permit limits, the County decided to implement a configuration of Selective Non-catalytic Reduction (SNCR) using urea as the reagent, coupled with flue gas recirculation (FGR). The advanced SNCR system uses 3 levels of urea injection in the furnace to ensure 1 Part per million dry volume, corrected to 7% O2, 12 month rolling average. The permit allows a 12 month time period following initial operation to fme tune the system. The limit for the first 12 months is 140ppm, 12 month rolling average; the 24 hour limit is 150 ppm, applicable at all times. injection of reagent at the optimum temperature zones. Since the amount of reagent/water injection required to achieve these aggressive NOx limits would negatively impact waste throughput and hence steam generation, the FDEP conceded to allow the furnace heat input limit to be increased by 6.0%, to MBtu per hour. This effectively increased the nominal design throughput to 636 tons per day, and will offset the negative impact associated with the elevated reagent injection rate. The FGR system recirculates a portion of flue gas (up to 19% of cleaned flue gas volume) from the induced draft fan outlet back to the furnace, via a FGR fan. The FGR limits thermal conversion of nitrogen in the fuel and combustion air, by limiting the oxygen content available for conversion to nitrogen oxides (NOx). Table 1 Notes: (a) Value shown is calculated equivalent to the actual permit limit of 20.61lg/m 3. (b) Projected based on operation at capacity for 8760 hours per year. Actual operating levels and time, on which compliance with the permit is determined, will be lower. (c) Compliance is determined based on the least stringent of the concentration or the removal efficiency. (d) Compliance determined on a 24- hour daily arithmetic average basis. (e) Compliance determined on a 12-month rolling average basis. Limit applies for the 12-month calendar period following initial operation only. (t) Compliance determined on a 12- month rolling average basis. (g) Compliance determined on a 4-hour block average basis. (h) Compliance determined on a 12- month rolling average basis. 98

3 (i) The requirements applicable to Units 1 and 2 allow reduced testing if the total dioxinlfuran concentrations are less than 15ngldcsm, corrected to 7% 02. (k) The limit is that visible emissions cannot be emitted for more than 5% of the observation period. NA = Not applicable. TABLE 1- FACILITY EMISSIONS COMPLIANCE COMPARISONS Units 1 & 2 Unit 3 Permit Permit Pollutant Limit Limit Particulates gr/dscf corrected to a 7%02 Iblhr Stack Opacity (%) Sulfur Dioxide (S02) ppm corrected to 7% O2 c NA 56.9 NA % 80% removal efficiency C Hydrogen Chloride (HCI) ppm corrected to 7% O2 c NA Iblhr NA removal efficiency C Nitrogen Oxides (NOx) 180 d 150 d/140 9/110 f ppm corrected to 7% O Ib/10 6 Btu 0.29 NA Carbon Monoxide (CO) /80h ppm corr. to 7% O /23.0 h Ib/10 6 Btu 0.10 NA Dioxins/Furans ng/dscm corr. to 7% O Ibll10 6 Btu NA Mercury (Hg) mg/dscm corr. to O2 c Ibll10 6 Btu NA removal efficiency C Lead (Pb) mg/dscm corr. to 7% O Ib/10 6 Btu NA Cadmium (Cd) rng/dscm corr. to 7% O2 NA NA Fugitive Emissions Opacity (%) k

4 Contractual Arrangements The original facility procurement was a traditional full scope Design, Build, and Operate contract. It was competitively bid, and resulted in an award to Covanta Lee, Inc 2 for the original facility construction, along with a 20 year operating contract. The County owns the facility, which was financed with 20 year bonds, including the usual bond covenants. Since the outcome of bankruptcy proceedings with Covanta 3 was uncertain at the time, the County decided to undertake the construction of the new unit on its own, using Covanta as construction manager. Under these arrangements, the stoker technology and equipment supply was sole-sourced to Martin, while the remainder of equipment was competitively bid, using design principals embodied in a "Basis of Design" (BOD) agreed to by the County and Covanta. The first major procurement was for an architect! engineer (NE) to provide engineering, design, and procurement assistance to the County, with Covanta providing oversight to ensure that appropriate standards and practices were followed. The architect!engineer selection resulted in an award to Burns & Roe, Inc. of Oradell, N.J. Long lead items including the new turbine-generator (20 MW nominal, awarded to Mitsubishi Heavy Industries), the boiler supply and erection (awarded to Babcock Power, Inc.), air pollution control system supply and erection (awarded to Alsthom Power, Inc.), and SNCR system supply (awarded to Fuel-Tech), formed the 2 Originally known as Ogden Martin System of Lee, Inc. 3 Covanta emerged from bankruptcy protection in 2004, and is now a publicly traded company listed on the NY Stock Exchange. backbone of the new unit. Subsequently, the balance of plant equipment (pumps, electrical transformers and switchgear, conveyors, ash handling components, water treatment systems, cooling tower, heat exchangers, valves, etc.) were specified, competitively bid, and ultimately directly purchased by the County. The erection of systems and equipment not proc red under separate furnish and erection contracts, was competitively bid under a General Contractor (GC) procurement, which was awarded to Casey Industrial, Inc. in late Key elements provided under the GC scope includes all foundation work and concrete supply, pilings (where deep foundations were required), structural steel beyond the boiler and APC battery limits, electrical systems beyond the furnish and erect battery limits, piping, valves, miscellaneous instruments and controls, and.... commissiomng services. The procurement process started with the use of Covanta' s standard specifications and the BOD, which were customized for project specific parameters by the AlE. The draft procurement specifications were then. reviewed and approved by Covanta and the County, and the AlE issued the specifications for competitive bidding to pre-established qualified bidders. Following receipt of bids, the NE produced a draft technical and economic bid evaluation, the results of which were subject to review and approval by the County and Covanta. After the competitive rankings of the bidders were agreed on, the County, assisted by the NE, negotiated terms and conditions for purchase, including resolution of any commercial exceptions taken by the successful bidder. With the procurement 100

5 package of specifications, bids, and contract documents, the County Solid Waste Division proceeded with obtaining authorization for procurement from the Board of County Commissioners, after which the actual purchase orders or contracts were executed. Over 55 procurement contracts were executed under this arrangement. The contractual arrangements with Covanta were substantially different from typical WTE full service procurements, where generally a Construction Agreement, including unit and facility acceptance criteria, are secured by performance and payment bonds. In this case, since the County assumed procurement and certain performance risks, there is no overall guarantee of the expansion project's cost or performance. During the early stages of project development, an Interim Agreement set forth general principals for going forward. The essential elements of this Interim Agreement included the terms of procurement of the Martin stoker equipment and its guarantees and warrantees, and the general principals regarding the Parties' respective responsibility during the engineering and design phase of the project. Subsequently, and in parallel with project development activities, two additional agreements were negotiated with Covanta. These contracts covered Interim Operations (through project acceptance) of the Expansion Project, along with project oversight responsibilities during construction and startup. Once the Expansion Project is accepted, a new Operating and Maintenance (O&M) Agreement will take effect, covering operation and maintenance of the expanded facility, including an extension of the original project term. Under these Agreements, Covanta is paid on a fixed fee basis for Expansion Project oversight responsibilities, and is paid a unit fee per ton for operation of the Expansion Project pending its acceptance. "Acceptance", as used herein, includes full compliance with all environmental requirements, including the aforementioned stringent NOx requirements. Compliance with other specific environmental performance requirements, including acid gas emissions (HCI and S02), particulates, dioxins and furans, and mercury falls upon the respective equipment supplier contracts and guarantees (principally for the air pollution control contract) and the stoker contract (for carbon monoxide, CO limits). If any failure to pass acceptance testing is due to Covanta' s fault in executing their project oversight responsibilities, they will be held responsible, limited by other monetary and performance issues contained in the Agreements. While it is unusual for a public entity in a "full service" arrangement to accept the risks regarding technology and emissions, their acceptance in this case is a reflection of the maturation of the WTE industry, and the County's understanding of these risks, which was gained through over 25 years of experience in the US market. Since risk management always comes with an associated dollar cost for the party retaining the risk, it was believed that Covanta would have demanded a substantial contingency in order to assume such risks, especially given its delicate financial situation at the time these agreements were conceived. In any case, the County has assumed certain risks associated with project construction 101

6 and perfonnance uncertamties, but has secured or arranged for agreements wherein the appropriate parties (such as equipment suppliers) are held responsible through the County's contracts. In return for accepting the remammg risks, the County's construction budget for the project is believed to be considerably less than would otherwise be the case under a typical full service procurement process. Upon final acceptance of the Expansion Project, Covanta will be responsible for subsequent operation within the requirements of all permits, as well as the other contractual responsibilities outlined in the O&M Agreement. Basic Design Criteria The basic design criterion is the ability to combust up to pennitted MSW capacity 4, based upon 5000 Btu per pound reference fuel. The boiler steam conditions for the new unit are identical to the existing units (865 psia at 830F superheat steam temperature). The boiler is a four pass design, with evaporator, superheater and economizer sections following the furnace (first) pass. Steam is conveyed to a stand-alone condensing turbine rated at 19.8 MWe, and subsequently condensed by cooling water from a new cross flow cooling tower using reclaimed water as the makeup water source. The generator output is sold to Seminole Electric, a Florida based electric cooperative, and wheeled over Florida Power & Light transmission lines. The County owns and is responsible for maintaining the high 4 Pennitted capacity of Unit 3 is 660 tons per day, and maximum heat input of MBtu per hour. Pennitted capacity of Units 1 & 2 is 660 tons per day, and maximum heat input of275 MBtu per hour. voltage interconnection equipment located in an expanded switchyard. The new unit is interconnected electrically with the existing units at the 13.8 KV voltage level, such that any of the units can support each other for in-plant power requirements. The new units are served by dual boiler feedpumps, one electric and one turbine driven, and there are no mechanical interconnections (steam or water side) between the new unit and the existing units. The furnace design utilizes Martin's "four row stitching" concept for introduction of overfire air. The furnace is 4 grate runs wide, and 13 steps deep, with residue removal through dual ram ash expellers. Overall furnace width is 32 feet, with three levels of urea injection located on the side and front walls. Boiler cleaning is principally with a conventional array of retractable and rotary sootblowers in the superheater, evaporator and economizer sections. The boiler includes two propane fired auxiliary burners for startup and shutdown operations, as well as for CO control during poor quality fuel operation. Flue gas from the boiler is treated in a conventional spray dryer absorber for acid gas removal, using slaked pebble lime as the reagent. A powdered activated carbon injection system is used for mercury control. A conventional pulse jet fabric filter with ten compartments is used for particulate control. Although not required by air quality permits, FGR is installed and will be used for enhanced SNCR system perfonnance. The Continuous Emissions Monitoring System (CEMS) is furnished by Covanta, and includes a Fourier Transfonn Infrared (FTIR) monitor for 102

7 on-line ammonia slip measurement. Although the FTIR is not a conventional CEMS measurement subject to EPA and DEP reporting requirements, the FTIR is used as a diagnostic tool to minimize slip and visible plumes. The FTIR is subject to periodic verification by wet chemistry (stack) testing techniques. There is no permit requirement for opacity outside the stack. The existing turbine building was expanded to accommodate the new turbine-generator and associated equipment. The crane rails on the existing turbine-generator service crane are extended in order to also serve the new turbine. New high and medium voltage electrical equipment, as well as distributed control system equipment is also housed in separate areas within the turbine building. The new boiler is located within a fully enclosed metal building, along with the air pollution control equipment. The existing ash loadout area is also expanded to accommodate the increase in residual volume, as well as to accommodate existing ferrous and non-ferrous removal equipment. The existing main control room accommodated the new unit's controls without physical expansion. Similarly, the main residue conveying equipment from the boiler to the ash house was usable as IS without modifications. The new unit is expected to produce approximately 610 kwhrs net per ton of reference waste, which is not a guaranteed parameter. Rather, the guarantee will be established during acceptance testing, and Covanta will be obliged to guarantee whatever value is actually achieved (less some margin) for the duration of the O&M Agreement. A notable water conservation feature incorporated into the new unit's design is the use of a sophisticated micro filtration and reverse osmosis membrane system for treatment of cooling tower blowdown. This system will enable boiler makeup water to be produced from the reclaimed water used in the cooling tower, essentially eliminating any potable water usage for process consumption. This is an advantageous feature, especially significant in Southwest Florida, where high growth rates continue to challenge the capacity of potable water supplies, which are typically derived from shallow wells. Construction Site construction activities commenced in late 2005, with the addition of a new flue in the existing stack. This was accomplished by lowering the flue pipe sections into the existing 275 foot tall concrete stack, using a large crane with boom extension. The next major milestone was the mobilization of the General Contractor, which occurred on 12/19/05. Over the next 12 weeks, the GC's major activities were the installation of over 220 concrete piles for support of major boiler steel, the air pollution control system, and the turbine building extension. Some delays were encountered in the piling installation, which required substantial subsequent work rescheduling in order to maintain overall project schedules. Other major milestones included: Delivery of the generator step up transformer in late February, 2006 Delivery of the turbine generator from Japan and Sweden in July, 2006 Mobilization of the boiler erection contractor March,

8 Mobilization of the APC erection contractor in June, 2006 Delivery of stoker components from Germany from March through November, 2006 Delivery of electrical relay panels in October, 2006 Erection of switchyard starting in July, 2006 Piping erection starting In September, 2006 First electrical energization In March, 2007 Mechanical completion forecast on April 1, 2007 (6 weeks behind original forecast) There have been several delays encountered throughout the construction period. Several items of equipment were delivered late, principally due to delays in receiving final vendor information. These included piping and pipe hangers, and key electrical relay panels. Overall, the GC did a good job in minimizing associated construction delays by reassigning work crews, strategic use of overtime for craft labor, and partial completion of work based upon information on hand. Two major developments since the last wave of major construction in the WTE industry in the 1990's significantly complicated construction of the Expansion Project. First, the substantial reconstruction activities occurring in the Southeastern regions of the US heavily impacted by hurricanes in 2004, created equipment and labor shortages throughout the region, if not nationwide. This dramatically increased the costs for certain commodities, most notably concrete and steel. Secondly, during the 15 year period when there was no new construction of WTE units in the U.S., many of the traditional equipment suppliers had vanished, merged with other firms, or no longer supported the WTE industry. Although qualified suppliers for all equipment were eventually found, in some cases the number of qualified contenders was reduced significantly, and delivery schedules were lengthened due to tight supplies or the need to import certain items from abroad. As of this writing, the milestone of first refuse fire remains April 7, 2007, despite the aforementioned delays. The startup, turnover and commissioning sequence has been re-worked to accomplish the same tasks in a more compressed time frame than forecast in the original project schedule. The Project Team is hopeful that the final milestone of Project Acceptance can still be accomplished by the originally scheduled date of July 15, Project Financing & Costs Table 2 presents overall project costs as budgeted and expected at completion. The project was financed by a combination of County equity and Solid Waste System Revenue Bonds, which were issued in early The overall project costs, including permitting, financing and construction amount to approximately $194,000 per ton per day of nominal capacity. 104

9 TABLE 2 - PROJECT COSTS Cost Component Estimated Cost Combustion/Boiler Equipment and Erection $ 32,797,090 Air Pollution Control/Chimney and Erection $ 13,744,402 Turbine Generator $ 4,828,530 Turbine Plant Equipment and Installation $ 2,653,199 Residue Handling $ 898,890 Balance of Equipment $ 5,911,716 General Construction $ 31,199,554 Project Design $ 6,547,556 Permitting $ 2,500,000 Miscellaneous Defined Direct Costs $ 5,569,744 Defined Direct Costs $ 106,650,681 Project Admin, Licenses and Miscellaneous $ 11,544,450 Contingency $ 5,000,000 Estimated Construction Price $ 123,195,