EXECTIVE SUMMARY TO DETERMINE EFFECTIVE RE-USE OF FLY ASH, BOTTOM ASH AND COAL DUST FROM CAÑON CITY POWER PLANT Prepared for: ICAST 25953 Gateway Drive Golden, CO 80401 and Aquila Networks 550 Highway 50 West Cañon City, CO 81212 Prepared by: CABJ Engineering Consultants 930 W. Moorhead Circle, Apt B Boulder, CO 80305 December 9, 2004 CABJ team members: Alia Friedel Bret Harper Jeff Jenkins Cathy Vos Volume 1 of 3: Executive Summary
Introduction On September 16, 2004, CABJ Engineering Consultants was awarded the contract to design a solution for the re-use of fly and bottom ash for the W N Clark power plant in Cañon City, CO. An Alternatives Assessment was delivered on October 28, 2004 recommending a specific solution. The final stipulation of the contract was to provide a 30% design for the proposed solution which will be delivered on December 9, 2004. This executive summary contains various considerations, findings, and the preliminary design for the recommended solution. For complete detail and all relevant computations please reference the Cañon City Plan. Current Conditions The W N Clark power plant is located in Cañon City, Colorado, and lies approximately 1 hour west of Colorado Springs. The power plant is located on the western edge of the city, and lies between the Arkansas River and the federal Administrative Maximum Penitentiary, dubbed Super Max. The plant burns approximately 500 tons of coal per day. They receive a delivery by Union Pacific rail twice a week to replenish their coal supply. Limited on-site rail space inhibits the large deliveries of coal which Union Pacific would prefer, and results in inconsistent delivery schedules. The solid waste products of fly and bottom ash are combined in a storage silo and all 70 tons per day is sent to a landfill for $8.60 per ton (Gaines). Figure 1-1 shows a schematic of the fuel and waste flow through the power plant. ES-1
Coal Pile Coal Hopper Bag House Filtered Air Front End Loader Coal Elevator Furnace Air Exhaust Fly Ash Wood Chip Pile Through Grate Bottom Ash Solids Waste Storage Silo To Landfill Figure 1-1: Flow schematic of fuel and waste through plant The power station remains in compliance with air pollution regulations by each boiler being equipped with a separate Mikro-Pul Model SR fabric filter dust collector. The captured fly ash from the bag-house filter systems is transported by means of a dry vacuum system to a storage silo which is emptied three to four times per day and transported along with the bottom ash to Phantom Landfill, located 16 miles east of the plant. The plant s fly ash contains approximately 40% carbon, and its inherent energy is a reason Aquila would like to re-use the ash. Future Conditions The inconsistencies in wood supply and chip size hinder attainment of the 5% maximum permitted wood fuel co-burn. A consistent wood source with smaller chips is being located to rectify this. To alleviate the coal supply problems, the construction of additional rail spurs are being considered, allowing for a greater number of cars to be stored on-site and thus reducing the number of trips that Union Pacific has to make. A $3 ES-2
million upgrade of the plants control systems are being planned and slowly implemented (Gaines email#1). Permitting Regulations The Cañon City power plant has a Title V air permit allowing them to burn up to 5% wood in their boilers. The plant is a stationary source for pollutants including sulfur dioxide, nitrogen oxides, and carbon dioxides (Operating Permit). The plant fits into the PSD (Prevention of Significant Deterioration) special category which allows emission of up to 100 tons a year of a regulated pollutant (Operating Permit). The permit also states that if the current handling of the fuel sources or wastes is changed, the permit will have to be updated (Operating Permit). Each boiler is equipped with a fabric filter dust collector which removes 99.9% of particulates 0.5 microns or greater. The gas steam discharge can not exceed 0.015 grains of particulate matter per cubic foot of gas discharged at any time (Operating Permit). If Aquila chooses to separate the fly and bottom ash they will need to monitor a new silo which will require them to change the existing air permit; in addition, the power plant will have to obtain a construction permit for the new facilities needed for the briquetting option, but the costs of these construction permits are minimal (IDEM Permit Guide). Constraints and Criteria A list of constraints and criteria were established to help evaluate the best option for the W N Clark power plant. The constraints that must be satisfied are: Avoidance of air re-permitting ES-3
Avoidance of fuel-handling re-permitting Demand for product. The comparative criteria as well as their corresponding normalized weight factors towards the final chosen option are: Present Value- 12% Avoidance of Re-permitting- 4% Employee Safety- 14% Large Scale Positive Effect on the Environment- 9% Reliability/Consistency of Process (maintenance concerns)- 9% Impact on Community and Aesthetics- 10% Minimal Complexity of the Process- 7% Site Considerations- 12% Use of Current Facilities- 9% Minimization of Liability- 13% Alternatives Assessment Process Using these constraints and criteria the CABJ design team came up with a complete list of alternatives. The design engineers researched these alternatives to find information on all the possible solutions. CABJ eliminated the alternatives that did not fulfill the constraints, or because further research revealed that some of the alternatives were not appropriate for Cañon City. The remaining 4 alternatives with pros and cons are listed in Table 1-1. A table of the present value cost for each of the four alternatives can be found in Table 1-2. ES-4
Table 1-1: Four final alternatives with pros and cons listed Table1-2: Present Value cost for each of the four alternatives Alternative Present Value Landfill ($219,730) Concrete ($183,449) Briquetting/ Landfill $202,825 Briquetting/ Compost $279,730 Decision Matrix To decide on a final design, a decision matrix was created to further assess the options using the weighted criteria. The majority of the weight in the decision making ES-5
process was placed on present value and employee safety. Fifty percent of the decision making weight was given to Bob Gaines, W N Clark s plant manager. Angie Bielefeldt, our design project professor; Joe Kost, from the USDA; Ravi Malhotra, a contact from ICAST; and the CABJ design team had an even split in the rest of the decision making weight. A score of 1 is poor while a score of 10 is excellent. The alternative with the best score was selected as the final selected design. Table 1-2 shows each option and their final score after being weighted against the criteria. Table 1-3: Decision matrix with criteria and final score Selected Design The new facility will consist of a new storage silo for the fly ash, a sawdust stockpile, and the actual briquette machine. The new silo will have air pollution monitoring equipment. A blower and hopper system will transport the fly ash to be mixed with the sawdust in a mixer. The sawdust stockpile will be enclosed in a shed to minimize the effects of the environment, including wind and added moisture from rain and snow. The ES-6
sawdust will be sucked into a hopper using a blower. This hopper will transfer a scaled amount of sawdust into the same mixer containing the fly ash. This mixture will be transported to the briquette machine by another blower. The briquette machine will be enclosed in a shed to protect it from the elements. The shed will have ventilation, electricity, and lighting. Finally the cooled briquettes will then be front-end loaded to the coal pile and burned in the boilers with the coal. Below in Figure1-3 the flow process of the new design facility can be viewed. Figure 1-2: Flow schematic of designed briquette facility The actual briquettes will be made from a ratio of fly ash and sawdust. CABJ visited Dr, Kurt Mackes at Colorado State University and made a range of briquettes summarized in Table 1-4 below. The ideal ratio, using all the available fly ash and all of the allowed sawdust, is 55% wood and 45% fly ash. Appendix 1-1 contains this calculation. This ratio was not tested. ES-7
Table 1-4: Observations of pellet ratios % wt Fly Ash % wt Wood Control 100 0 Control 0 100 Excess Fly Ash 62 38 Excess Wood 25 75 Even Mixture 50 50 Observation (no heat) Pellet crumbled very easily Pellet crumbled very easily Pellet crumbled very easily Pellet crumbled very easily Pellet crumbled very easily Observation (with heat) NA More stable More stable More stable More stable For the testing, a ten gram mixture was made for each of the various ratios using a percent weight measurement. The pelletizer in this experiment was hand operated and not motorized. The first batch of mixtures was made into pellets without any heat or moisture added to them. The results were not satisfactory because the pellets crumbled very easily. All the mixtures were then tested again with an added heat component before they were palletized. They were put in the oven and heated to 100º C for ten minutes. A new set of pellets were made with both heat and pressure. This second set held together better but still crumbled easily. From this lab experience it was concluded that the best range to begin further analysis on the determination of an ideal composition would be 38%wt wood and 62%wt fly ash to 75%wt wood and 25%wt fly ash. This is because the briquettes with these compositions held together the best with both heat and pressure. Location of New Facility Aqulia and the W N Clark Plant Manager, Bob Gaines, expressed the following concerns for selecting the location of the new briquette operations: Distance to coal pile ES-8
Maintaining current fuel handling techniques Enough land to construct the facility such that all equipment lies within close proximity to each other. Taking these concerns into account, CABJ Engineering Consultants has selected the east end of boiler 2 (as denoted by the building in red in Figure 1-3) as the location for the facility. There is enough open land for the silo, sawdust stockpile, and briquette machine here. This location is also near the coal pile, allowing easy transport of the briquettes. Piping and blowers will transport the material throughout the facility. The air permit will not have to be fully opened, only amended for monitoring the new ash silo with this system. Below in Figure 1-3 is a site footprint showing the location of the entire briquette facility. Figure 1-3: Location of briquette facility ES-9
Construction Phasing The construction phasing for this project can be found in the attached Gantt chart Figure 1-4. The project was set to start as of New Year 2005 and is using a scale of weeks. It is broken down so that permitting, ground clearing and site preparation, and foundations must be completed before anything else can be started. There are three main areas of construction which each include more detailed construction phasing. The three main areas are: the sawdust stockpile, fly ash silo, and the briquette making facility. Please reference Figure 1-4 to see more detailed phasing. The red bars represent critical tasks that must be completed before the next can start, and the blue bars are normal tasks. The blue arrows show links between the different tasks, and the black bars are summary bars. It is recommended that the same contractor complete all the needed construction in order to keep the costs to a minimum. This will also help to keep the construction running smoothly. Figure1-4: Construction phasing shown in a Gantt chart ES-10
Project Costs After discussions with both Aquila and ICAST, it was determined that Aquila should have an investor construct the new facility, operate it, and maintain it. If Aquila were to operate the process, any profits that they would make would have to be distributed to the public. If an independent contractor were to operate the process, they would be able to keep the profit and Aquila would be able to keep any profit they made from leasing the facility. The total capital cost to build the facility and to separate the ash is $673,392. This cost includes all of the equipment involved to transport contain both the fly ash and saw dust. It also contains the briquetting machine. The operation of the facility will cost approximately $51,100 annually and will be operated by an independent contractor, as discussed above. Maintenance of the both the facility and equipment will also be done by the contractor and will have an annual cost of about $9000. The following figure (Figure 1-5) is the estimate sorted to its highest level so that there are not any details displayed and is broken down by the type of work each item will consist of. ES-11
Figure 1-5: Estimate at group sort level ES-12
Conclusion Our recommended option is to build a facility to briquette the fly ash produced at the W N Clark power plant with locally produced sawdust, while sending the bottom ash to a composting operation. If composting becomes a non-viable option, then Aquila can continue to landfill the bottom ash. The footprint of the new facility will be 900 ft 2 and will contain the sawdust stockpile and briquetting machinery. Connected to this building is a fly ash storage silo with a capacity of 150 cubic yards. Following a 6 month permitting process, the construction process will take approximately 15 weeks. The total capital cost to construct the facility and the new fly ash transportation system is $673,392, which is recommended to be supplied by an independent investor. This investor would also be responsible for an annual operation and maintenance cost of approximately $9,100 for this facility. The investor stands to profit $311,338 annually with a capitol cost pay back period of 10 years. Aquila will profit $279,730 annually if the bottom ash is composted and $202,825 annually if the bottom ash is continued to be landfilled. ES-13