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HomeMy WebLinkAboutCity Tribe Biomass Energy Conservation R3 Trip Report Tanana WTP Biomass Assessment 2022 MEMORANDUM DATE: March 21, 2022 FROM: Utility Operations Specialist IV SUBJECT: Trip Report, Tanana – Water Treatment Plant/Washeteria Biomass Heating System Assessment (ZA2) – March 8-10, 2022 TO: FOR THE RECORD OBJECTIVES: 1. Assess the condition and operation of the water treatment plant (WTP)/washeteria biomass heating system. 2. Collect and compile information for development of a biomass heat system audit. 3. Develop a rapport with the utility/biomass system operator regarding utility operation. 4. Troubleshoot non-functional remote monitoring (RM) equipment installed in 2020. 5. Assess the operation and condition of the water utility system. 6. Assess heating system improvements associated with the Infrastructure Protection Funding (IPF) and 2020 Coronavirus Aid, Relief and Economic Security (CARES) Act work performed in December 2020. CONTACTS: Mr. James Roberts, Water Plant Operator, Too’gha Utility Inc. Ms. Christine Erhart, Finance/Administration, Tanana Tribal Council (TTC) Mr. Victor Joseph, Executive Director, TTC ACCOMPANIED BY: Ms. Bailey Gamble, Mechanical Engineer III, ANTHC FINDINGS AND ACCOMPLISHMENTS: Note: Minor repairs and assessments were conducted on the biomass system during a site visit in December 2020. We departed Anchorage at 9:10 a.m. through Fairbanks via Alaska Airlines and arrived in Tanana via Wright Air at about 3:05 p.m. Mr. James Roberts met us at the airport and brought us to the WTP. We later went to Tanana Commercial store to set up lodging. Trip Report, Tanana – WTP/Washeteria Biomass System Assessment Page 2 March 8-10, 2022 WTP/Washeteria - Biomass Mr. Roberts explained that the biomass boiler system was operated as the primary heat source for the WTP/washeteria this last season and the community hadn’t burned much fuel oil through the oil-fired boilers. He said he lead a small group of workers last fall to harvest and stockpile wood for the winter’s biomass fuel supply. They dedicated 20 work days to harvesting dry standing spruce trees from local forest fire areas. He stressed the importance of getting the wood cut to length, sized, stacked, and ready to fill the boilers stating: “I haven’t had to touch a saw or axe all year.” Mr. Roberts demonstrated filling and starting a fire in the boiler units. We observed another worker hauling wood with a plastic toboggan approximately 80 feet from a pile under the snow to the inside of the biomass garage. Mr. Roberts said they had already used up most of the wood that was staged closer to the building. The facility lacks a woodshed or shelter for bulk wood storage. We discussed different methods of woodcutting, handling, storing and moving wood from the outside storage area (under the snow/drifts) to inside the facility to feed the boilers. Handling seasonal wood fuel (90-plus cords) is labor- and time-intensive. Minimizing handling was discussed. The following was observed: 1. The Garn boilers’ fresh air intakes were disconnected from a through-wall vent pipe due to frosting condensation problems. The frosting condensation is primarily caused by intakes not built and insulated per the manufacturer’s installation directions. Boilers are designed to draw combustion air directly from the outside. Note: Supply and return piping installed at each boiler did not provide clearance to refit the intake to the manufacturer’s recommendation. Rehabbing the faulty intakes will require some creative alteration to correct. 2. Potential corrosion exists with the Garn boilers. a) Dielectric isolation between the Garn carbon steel boiler to copper pipe was not observed during the inspection. The boilers are piped using copper immediately exiting the boilers after the steel flex lines. No dielectric separation exists. Most of the copper piping utilizes Pro-Press fittings. Pro-Press fittings are crimped and rely on an O-ring seal. Fitting and valves cannot be disassembled or reused for piping alterations. If piping changes are required, new replacement pipe, valves and fitting would be needed. b) Existing sacrificial anode rods inside the boiler were observed to be depleted and require replacement. However, Garn now recommends boiler water filtering and ensuring electric isolation of the boiler body instead of anode rod replacement for protecting against corrosion. c) The system has no filtration. Garn recommends continuous removal of suspended particulates through a bypass filter and passing flow through the filtration system when filling. d) The boiler water was tested with a pH litmus paper with a qualitative result system. The result indicated high corrosivity. Trip Report, Tanana – WTP/Washeteria Biomass System Assessment Page 3 March 8-10, 2022 e) Note: Service life for the Garn boilers is dependent on the water condition and proper maintenance. Upgrading and adding Garn boiler filters and a testing and treatment plan should be strongly considered. 7. The interior boiler reservoirs are coated with built-up calcification/sediment. Draining and pressure-washer cleaning inside all boiler tanks is recommended to remove the buildup and sediment. Refilling with clean water and proper anti-corrosion additives is recommended. Buildup inside the boiler could potentially contribute to inefficient heat transfer. 8. The operator reports adding 70-80 gallons of water to the biomass boiler loop every 7-10 days. This primary cause is likely evaporation through the manway covers where the low water sensor is inserted. Expected water loss is closer to 50 gallons per year. New, two- part manway doors with properly sealed low-water sensor penetrations should be considered. 9. Boilers are piped in parallel such that the supply is a mix of flow from all three reservoirs. Two out of three boilers were being fired. Isolating unused boilers by closing the isolation valves will prevent mixing of heated and cold water and increase supply temperatures. Note: Valves should be opened to allow slow warming of an unused boiler by the other boilers before firing for the first time after being offline/isolated from the system. 10. An inline strainer is on the Garn boiler supply line between the boiler and upstream of the circulation pump. It is unknown when the strainer screen was last cleaned. The strainer is also positioned downward, making access for cleaning difficult. Rotating it a 1/4 turn sideways would make cleaning access easier. No pressure gauges exist before or after the strainer for monitoring differential pressure or pressure at the inlet of the circulation pump. Monitoring and periodic cleaning of the screen is required if buildup develops and results in lower pressure to the circulation pump. Minimal inlet pressure at the circulation pump should be maintained to reduce hot water vaporization and pump cavitation and to extend the service life of the circulation pump. 11. No pressure gauge exists on the circulation pump discharge or return manifold. Gauges are recommended to monitor pump performance and operational system pressure. 12. Mr. Roberts expressed concern about the inside temperature of biomass garage getting too low in severe -40 to -50°F weather conditions. Part of the heat loss can be attributed to the incorrect boiler combustion air being drawn from inside the facility and replaced with the cold outside air coming in from wall vents and directly mixing with the inside air, cooling the room. Correcting the boiler combustion air venting as described above should help to limit low-temperature conditions inside the garage. 13. Mr. Roberts also mentioned a need for a backup heat source in the event of an electrical power outage. Backup heat was needed to prevent the biomass boilers/pumps/lines (filled with water) from freezing. Discussion regarding backup options led to a conversation about re-establishing operation of the backup generator provided for the WTP/washeteria. Electrical power service for biomass is provided from the WTP/washeteria electrical distribution panel, so the backup generator could potentially provide backup power to the biomass. The generator fuel lines were previously disconnected by the community in Trip Report, Tanana – WTP/Washeteria Biomass System Assessment Page 4 March 8-10, 2022 2020 when fuel lines to the oil-fired boilers’ automatic day tank were blocked with ice. The fuel piping lines should be reconnected and the backup generator should be returned to operational status. 14. Insulation in the biomass boiler garage ceiling was observed limited/lacking. Repairs of damage from a fire that almost burned down the facility did not add enough replacement ceiling insulation. Additional blown-in or fiberglass insulation would reduce heat loss and help to address concerns about low inside temperature. 15. Both gable-end roof vents are damaged. The washeteria side is wide open to blowing snow and rain. Replacement of both vents is needed. 16. There is fire damage on the northwest corner of building. Snow and drifts made closer inspection difficult. Investigation after the snow melts is recommended to evaluate damage. Insulation and siding repair might be required to reduce garage heat loss. 17. The side manway access door (3’ x 6’-8” standard residential exterior door) does not shut properly or seal. The operator relies on a rag looped through the open door knob hole to tie off outside to keep door somewhat shut. This contributes to heat loss. It is assumed that building movement and shifting caused the door closure problems. Door repair or replacement is required. Since biomass wood is primarily hauled through this door, building a larger, more robust field-fabricated door was discussed. 18. The biomass garage door is not primarily used to transfer wood into facility. Garage doors in general typically do not have high R-insulation value. Improvements by better sealing or adding insulation to the door was discussed. 19. No cooling fan ventilation exists. Observation during a 2019 trip showed the garage door was left open for cooling during warm weather. 20. Small pop-out air vents are installed high on the exterior walls. 21. Lighting inside the biomass garage is minimal and dim. New LED fixtures would be beneficial. 22. Huffing by the Garn boilers was observed. Huffing is not unusual during boiler startup using dry, smaller-sized, fast-burning wood such as that currently used. 23. Mr. Roberts replaced one of the Garn boiler blower motor units. 24. Mr. Roberts ordered some replacement parts direct from Garn in Minnesota. Cleaning brushes or spare gasket sets for flue passages was not observed. A critical spare parts list and maintenance tools specifically for Garn boiler operation should be developed, ordered and kept on hand. Annual cleaning of the boiler’s flue pipe passages should be performed and would improve heat transfer efficiencies from biomass fire to the heated water. 25. Storage/shelving space for spare parts is limited inside garage. Adding more shelving and potentially a small workbench would be beneficial for biomass and chainsaw operation and maintenance. 26. The fire chamber bricks inside the boilers are in poor condition, broken or missing. Replacement should be considered to protect and extend the service life of the fire chambers. Trip Report, Tanana – WTP/Washeteria Biomass System Assessment Page 5 March 8-10, 2022 27. All the Garn boilers’ fire chamber door handles and hinge pins are worn and should be replaced for positive door seal. Handle pins/bolts were added to doors in December 2020 to safely secure the handle latch when boilers are operating during huffing periods. Huffing creates a risk of unlatching and a slight opening of the door resulting in burning embers popping out into the garage. This is a fire hazard when wood chips and stacked firewood is nearby. 28. A short plywood skirt/apron is in front of the Garn boiler doors on top of the foundation frame. Replacement with sheet metal should be considered to reduce fire hazard from embers escaping from the fire chambers. 29. There is no moisture meter onsite to test for optimal moisture content of the wood supply. 30. The biomass supply and return lines between the biomass garage and the WTP boiler room are fed through two 6-inch arctic insulated carrier pipes. The supply and return line are two sets of 2-inch PEX piping (four pipes total). The lines are run high above the Garn boilers’ water level and are run even higher within the WTP boiler room into the mechanical area to the main heat exchanger. This heat exchanger is the interface of the biomass heat and the heating return line to WTP oil fired boilers. The high elevation of the piping creates air lock issues for the biomass boiler system, which is open to atmosphere. High point air reliefs to release trapped air can only be manually operated, requiring water pressure to evacuate air in the line or use of pressured water flow/velocity to push air back down into the Garn boiler. Alterations to lower the lines would require a major mechanical refitting of the biomass piping system between the garage and inside the WTP. Although not mechanically ideal, the existing system can and does operate well to transfer heat. 31. The copper 2-inch fitting on the biomass supply line above the No. 1 oil-fired boiler in the WTP has been leaking since observed in December 2020 and requires repair. 32. The copper 2-inch biomass supply line high point in the mechanical room area (before it drops into biomass heat exchanger) requires installation of a manual air relief tap and isolation valve. 33. There are no pressure gauges on the biomass heat lines to the heat exchanger (HX) supply or return manifold to verify differential pressures and/or a blocked or fouled HX. 34. There is no supply temperature gauge prior to the biomass HX. There is only a return line gauge. 35. There is no dedicated HX flushing port for the biomass main heat exchanger. 36. The three-way valve stem on the biomass three-way globe valve has developed a small leak. A calcium-type buildup was observed around the valve near the leak. 37. The actuator for the main HX three-way valve was replaced during the CARES Act work conducted during December 2020. It was determined at that time the three-way valve wasn’t required and serves as a redundant control. The heated hydronic side of the HX is tapped on nodes located on the building’s heat return line with a heat injection pump. This pump is controlled to start and stop to inject heat based on the available biomass supply to the HX and the temperature differential of the WTP boiler return. The three- way valve also operates based on the same differential temperature. The three-way valve Trip Report, Tanana – WTP/Washeteria Biomass System Assessment Page 6 March 8-10, 2022 and actuator should be considered for removal to eliminate redundancy and simplify the heat control operation. The three-way valve could be replaced with manual isolation valves at the HX supply and return ports with a manual bypass valve between supply and return. Removal would simplify heating control with one less failure point. 38. The main biomass heat exchanger is a plate and frame Ameridex product 95312 with 2- 1/2-inch flanged ports. Plate and frame HX units can be dismantled, cleaned, and rebuilt. Additional plates can potentially be added or removed to increase or reduce heat transfer capacity. However, plate gaskets can harden and fail requiring periodic replacement. The typical design life for the plate gaskets is 7-20 years dependent on heat and service. Gasket or plate assembly replacement is a relatively simple task. Poor water quality (corrosive/low pH/ suspended solids) can corrode or erode plates to failure and sediment buildup can foul and plug passages, reducing heat transfer. Replacement of the heat exchanger gaskets and pre-gasket plate assembly should be considered as part of the critical spare parts. The WTP/washeteria oil fired boilers were never observed to operate during our trip. Sufficient heat was supplied by the biomass system. The Tanana biomass system, although not perfect, does work well when operated correctly and has a proven ability to provide heat for the WTP and washeteria and meet heated water system demands, which defers the purchase or use of heating oil. WTP/Washeteria Backup Generator Module The backup generator is a 55-Kilowatt (kW) three-phase Kohler powered by a John Deere diesel motor. The generator is not currently operational. The generator is housed inside a small heated, insulated generator module located west of the WTP/water storage tank (WST). Heat is provided by a wall-mounted electrical 240 volt X 4000 watt heater. There is an electrical block heater on the generator engine. There was a total of 154.5 operational hours on generator meter. The fuel line from the double-walled storage tanks were disconnected in 2020. Filters, engine coolant fluid, and an oil change are required to return the unit back into service. 1. The disconnected fuel line previously supplied fuel from the large double-walled storage tank to the automatic day tank located in the module that in turn provides pre-heated fuel storage to the generator motor. The fuel lines needs to be reconnected. 2. The battery shows corrosion on both terminals and needs replacement. 3. The generator module has settled and requires leveling. 4. The combustion make-up air and cooling system duct and louvers will require functional testing after the generator unit is started and operated under load. 5. The fluorescent lighting inside the module appeared to struggle to turn on. Replacement LED lighting is recommended. 6. An automatic double-throw transfer switch is located inside the WTP immediately outside the boiler room directly next to the C electrical distribution breaker panels. Functional testing of the transfer switch should be completed after repair/startup of the backup generator. Trip Report, Tanana – WTP/Washeteria Biomass System Assessment Page 7 March 8-10, 2022 The backup generator and transfer switch need to be returned to operational service for emergency events when grid power fails. Having backup electrical power available will prevent freeze-ups and maintain required heat support systems for the WTP, washeteria, WST, water distribution and the biomass heating systems. Solar Panel Photovoltaic (PV) System A solar array consisting of 42 panels is mounted to the south side of the WTP/washeteria roof. The 5.5-kW array was installed around 2007. The array is mounted upright with Unistrut supports fastened to the roof. The array was not covered with snow during the visit. It was apparently shut off due to the local power company not allowing the PV system to back-feed power into the local grid power. 1. Each panel is a Kyocera Model KC130TM (ser. 0828HA4860) Pmax 130W. All the panels look to be in good condition (no rock/other damage observed). 2. The power inverter is a Xantrex Utility Interactive Inverter model GT5.0-NA-240/208 UL-05. The inverter was manufactured in August 2007. The unit is located next to the backup generator transfer switch outside the WTP boiler room. 3. When placing the system switch into the on position, the inverter indicates a ground fault. Pending further assessment of the PV array’s functionality, the existing system should be brought back online or replaced with newer panels in conjunction with a solution to maximize utilization without back-feeding into the grid. Integration of battery energy storage as well as utilizing solar power for heat should be evaluated. Applying the electrical energy directly to water systems, space heat or possibly biomass heat integration could provide useful benefit and further reduce utility operational costs. Remote Monitoring (RM) System The RM system installed during 2020 had not been working or reporting for approximately 180 days prior to our trip. The operator located the modem during the trip and discovered that it was unplugged in the Too’gha office on the east side of the washeteria. Plugging the modem back in corrected the problem and connection was re-established. However, sensor readings sometimes lagged by an hour or two, likely due to poor cellular connection. We discussed with Mr. Roberts installing additional sensors. The website link for the RM system was provided and set up on the Too’gha office computer. Note: The office has internet service but no Wi-Fi router. Providing wall laminates about RM operation and maintenance would be beneficial. Upgrade to a Wi-Fi- based system is recommended in order to generate more useful real-time output. IPF Heating Improvements (Continued 2020 CARES Act-Funded Efforts) Our December 2020 CARES Act efforts resulted in training the operator on replacement of heating system valves, actuators, and T775 controllers with new sensors for the raw water glycol loop, raw water heat-add, East and West distribution loops, and the WST heat-add. A spare replacement heat exchanger was provided for the distribution loops but not installed. (The existing HX is still functional.) The actuator for the biomass three-way heat control valve was replaced, including a new T775 controller, and four flush hydrants were provided for the water distribution system. Trip Report, Tanana – WTP/Washeteria Biomass System Assessment Page 8 March 8-10, 2022 During the December 2020 work, the associated IPF funding was not available so we did not finish all improvements. The existing HX piping is not standard throughout the plant and does not include all the normal pressure relief valves (PRVs), temperature gauges, pressure gauges or flush ports. The IPF-funded efforts plan to address this to improve HX operation and maintenance. Efforts made during trip include: 1. Detailed pictures of all HX system piping were taken for improvement development planning. 2. Mechanical parts left over from CARES work efforts were sorted and inventoried by taking pictures. Fittings are planned to be used to supplement needed parts. Planning of work with mechanical isometric drawings of each HX system will need to be developed, including an associate materials take-off list for the materials and equipment required. A return trip to Tanana for the work will be tentatively planned for later summer/fall of 2022. Other WTP/Washeteria Upgrade Work During the trip, we observed the Fairbanks-based HVAC LLC contractor working to replace the washeteria dryers. The existing air-to-air heat exchangers and associated ductwork was being removed in preparation for new hydronic dryers. Other mechanical and heating work for the tribal council within the community was included. Project materials were hauled by the contractor’s trucks using the Fairbanks Manley Tanana road. An ice road across the river was established. Tanana Raw Water Intake and Treatment System Tanana’s raw water comes from the river during the winter or the surface-influenced well next to the river during the summer. The system’s intermittent water-making requires that the operator make a hole in the river ice about 100 feet from shore to insert the submersible pump, then remove the pump when water-making is complete. The operator then uses compressed air to blow out any water remaining in the line from the pump house to the pump to prevent freezing. The line remains, marked with flags and resting on top of the ice, when not in use. The operator expressed interest in developing a temporary protective structure at the water access point. The treatment and associated monitoring falls under the surface water treatment rule. The water treatment monitoring equipment was observed to be outdated, obsolete and non-functional. It was again observed that the finished water turbidity meter is not functional. The turbidity monitoring was originally recognized as non-functional during the December 2020 CARES Act work. In mid-January 2021 with Mr. Lee Meckel, remote maintenance worker (RMW) with Tanana Chiefs Conference (TCC), onsite, the Hach 1720D turbidity meter and the old AquaTrend/SOM linked to the wall chart recorder were re-programmed. This effort required calling the Hach factory representative for assistance. With the information provided by Hach, the equipment was restored to operation, however it appears that wasn’t a permanent fix or solution. Trip Report, Tanana – WTP/Washeteria Biomass System Assessment Page 9 March 8-10, 2022 Mr. Roberts stated he has repeatedly re-programmed the unit using the literature, but the unit disconnects and drops out shortly after each re-programming sequence when he leaves the plant. A solution to correct this should be identified. We departed Tanana at about 3:20 p.m. March 10 via Wright Air and arrived in Anchorage at about 8:49 p.m. via Alaska Air. RECOMMENDATIONS AND/OR CONCLUSIONS: 1. Assist in the development of a Tanana WTP/washeteria biomass heating system audit and a prioritized list of potential improvements 2. Work with community to provide recommendations to repair the WTP/washeteria’s backup emergency generator. 3. Research alternative electrical/heat use of the solar panel array/voltaic system. 4. Continue monitoring the RM system to confirm whether operational. Develop RM laminates to provide operation and maintenance guidance. 5. Develop IPF HX improvements isometrics and material take-off, order materials, and ship to Tanana. Set up work trip after materials arrive in Tanana (late summer/early fall 2022). 6. Assist community with possible improvement to the non-functional surface water treatment turbidity monitoring. Martin Wortman cc: James Roberts, Water Plant Operator, Too’gha Utility Inc. Cliff Wheil, President, Too’gha Utility Inc. Christine Erhart, Finance/Administration, TTC Victor Joseph, Executive Director, TTC ec: Lee Meckel, RMW, TCC Noah Tsigonis, RMW Supervisor, TCC Oscar Menendez, Village Safe Water Engineer II, Alaska Department of Environmental Conservation (ADEC) Susan Randlett, Village Safe Water Engineer I, ADEC DEHE – Brian Menghini/ Valerie Zeedar/ Bailey Gamble/ Cindy Baldwin Trip Report, Tanana – WTP/Washeteria Biomass System Assessment Page 10 March 8-10, 2022 Biomass Boiler Building Garn Biomass Boilers Trip Report, Tanana – WTP/Washeteria Biomass System Assessment Page 11 March 8-10, 2022 Combustion Air Intake WTP/Washeteria Backup Generator Module Trip Report, Tanana – WTP/Washeteria Biomass System Assessment Page 12 March 8-10, 2022 Solar Panel PV System Trip Report, Tanana – WTP/Washeteria Biomass System Assessment Page 13 March 8-10, 2022 Obsolete/Non-Functional Water Treatment Monitoring Equipment