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Chena Power, LLC Biomass-Fired Organic Rankine Cycle System Operation Report - Oct 2013 - REF Grant 2195358
4RC Electrical Power System for Biomass Application P.700.0127 United Technologies Research Center 411 Silver Lane East Hartford, CT 06 108 Team Members: Fred Cogswell, Ph.D., Ulf Jonsson, Ph.D. Ahmad M. Mahmoud, Ph.D. October 1, 2013 United Technologies Research Center Subject to the EAR, ECCN: EAR99. This information is subject to the export control laws of the United States, specifically including the Export Administration Regulations (EAR), 15 C.F.R. Part 730 et seq. Transfer, retransfer or disclosure of this data by any means to a non - US person (individual or company), whether in the U.S, or abroad, without any required export license or other approval from the U.S. Govt. is prohibited. UTC Proprietary - This material contains proprietary information of United Technologies Corporation. Any copying, distribution, or dissemination of the contents of this material is strictly prohibited and may be unlawful without the express written permission of UTC. If you have obtained this material in error, please notify UTRC Counsel at (860) 610-7948 immediately. UTC PROPRIETARY - Export Controlled - ECCN: EAR99 Executive Summary The United Technologies Research Center (UTRC) (under a subcontract from Chena Power February 15, 2009) have designed and developed an ORC power generation system that is potentially capable of producing 400kW net (ORC system) power under nominal conditions using the thermal heat from a biomass heater. An additional 60kW of parasitics are projected to run the cooling pumps and the oil system. The down -selected concept consists of the use of five high-speed direct -drive (HSDD) oil -free turbines in a non-flammable highly recuperated R245fa cycle. The HSDD turbine/ generators utilize magnetic bearings to overcome decomposition limits associated with the oil and inverter - based power electronics to eliminate the need for an inefficient gearing system. This cycle can meet the net power generation requirements and can achieve a system thermal efficiency greater than 19%. The proposed 400kW system, minus two turbine/ generator sets, have been successfully fabricated and installed at a location in Alaska at Chena Power. In order to produce 400kW net power, modifications to the system are required. These modifications include upgrading the refrigerant pump and lines to incorporate two additional turbine/ generator sets. These modifications are detailed in Section 4. The demonstration of the installed technology is pending several outstanding items that have prevented the installed system (configured with 3 out of 5 turbine/ generator sets) from operating reliably at full speed and power in a continuous fashion. These items include: 1) evaluating and resolving (if any) the designed motor cooling schemes, 2) evaluating and resolving (if any) issues related to the excessive inverter harmonics and 3) tuning the power electronics and magnetic bearings. If resolved the currently installed 3 turbine/ generator sets are capable of producing 280kW of net power. This final report serves as the final deliverable for this subcontract with Chena Power and provides an evaluation of technology as well as recommendations for future work (outside scope of subcontract). UTC PROPRIETARY - Exnort Controlled - ECCN: EAR99 2 Table of Contents Tableof Figures and Tables........................................................................................ 1. Introduction........................................................................................................... . 1.1 Proj ect Obj ectives............................................................................................ 1.2 ORC Options.................................................................................................... 1.3 Innovative Technologies.................................................................................. 1.4 Statement of Work & Requirements................................................................ 2. Technology Description................................................................. 2.1 Thermodynamic Cycles........................................................... 2.1.1 Cascaded cycle.................................................................. 2.1.2 Bottoming cycle only ........................................................ 2.1.3 Hot Oil system and control ............................................... 2.2 HSDD (High -Speed Direct -Drive} turbine/ enerators 0 5 6 7 7 .......................... 9 .......................... 9 g...................... 2.2.1 Refrigerant and seals.................................................................... 2.2.2 Generator Poles and required inverter frequency ........................ 2 2 3 Cooling and thermal management ................... 9 ................. 14 ................. 15 ................. 16 ................. 17 ................. 17 ................................................................... 18 2.3 Magnetic Bearings................................................................................................. 20 2.4 Power Electronics.................................................................................................. 20 2.4.1 Hardware.......................................................................................................... 20 2.4.2 Startup of the Power system............................................................................ 22 2.4.3 Startup of the generators.................................................................................. 23 3. System Installation and commissioning....................................................................... 23 3.1 Installation of bottoming cycle.............................................................................. 23 4. Recommendations........................................................................................................29 4.1 Topping cycle liability........................................................................................... 29 4.2 Thermodynamic analysis of 5-turbine bottoming cycle ........................................ 30 4.3 Analysis of components and recommendations..................................................... 31 4.3.1 Turbine-generators..........................................................................................32 4.3.2 Condensers and recuperators.......................................................................... 32 4.3.3 Evaporators and pre-heater............................................................................. 32 4.3.4 Refrigerant Pump............................................................................................ 32 4.3.5 Oil Circulation pump...................................................................................... 33 4.3.6 Power electronics and bearing controllers...................................................... 33 4.3.7 Valves............................................................................................................. 33 4.3.8 Sensors and VB monitoring code................................................................... 34 4.3.9 System ControlIer........................................................................................... 34 4.4 Outstanding items.................................................................................................. 35 5. Summary........................................................................................37 UTC PROPRIETARY - Export Controlled - ECCN: EAR99 3 Table of Figures and Tables Figure 1: The Biomass site at K&K Recycling is located in North Pole Alaska (8 miles from Fairbanks) close to the Tanana River......................................................................... 6 Figure 2: Pellets produced by Chena Power from recycled cardboard ............................... 6 Figure 3: Temperature as a function of normalized enthalpy through heat exchangers between topping and bottoming cycles............................................................................. 11 Figure 4: PH and TS diagram for topping cycle, Siloxane MM...................................... 11 Figure 5: PH and TS diagram for bottoming cycle, R245fa............................................ 12 Figure 6: Cascaded cycle P&ID. Bottom: 245fa, 3 turbines. Top: Siloxane MM, 2 turbines.............................................................................................................................. 13 Figure 7. Bottoming only P&ID, with four turbines........................................................ 15 Figure 8: Hot -oil loop and control................................................................................... 16 Figure 9: HSDD (High-speed direct -drive) turbine/generator drawing and prototype unit. ........................................................................................................................................... 18 Figure 10: Schematic of HSDD turbine/generator, HST bearing design ......................... 18 Figure 11: Schematic of HSDD turbine/generator, S2M bearing design ........................ 18 Figure 12: Generator cooling for topping cycle............................................................... 20 Figure 13: One -line diagram of ORC power plant. Key power components labeled A-G, provided by Vacon, are referenced in Table 6.................................................................. 22 Figure 14: View of ORC plant......................................................................................... 24 Figure 15: View down platform showing condensers, recuperators and evaporators..... 25 Figure 16: View of upper platform showing oil control components .............................. 26 Figure 17: View of main (lower) platform looking from heat exchangers to turbines.... 26 Figure 18: Left side of power panel................................................................................. 27 Figure 19: Left side of power panel................................................................................. 28 Figure 20: Control Panel (before integration).................................................................. 29 Figure 21: TS and PH diagram for single R245fa cycle with 5 turbines .......................... 31 Figure 22: Manufacture data for oil pump. Model 080-160 should produce 400gpm at 40ftof head....................................................................................................................... 33 Figure 23: VB monitoring code screen with sensor changes highlighted ....................... 35 Figure 24: Project timeline..................................................................... 34 Table 1: ORC refiigerant properties................................................................................ 10 Table 2: Primary Components for Cascaded Cycle......................................................... 12 Table 3. Primary Components for Bottoming Only Cycle .............................................. 14 Table 4: Turbine/generator attributes ............................................................................... 17 Table 5: Electrical frequency with turbine operating at 28,000 rpm .............................. 17 Table 6: Power electronics key components provided by Vacon................................... 22 Table 7: Calculation of parasitic power.......................................................................... 31 UTC PROPRIETARY - Export Controlled - ECCN: EAR99 4 1. Introduction 1.1 Project Objectives The objective this project was to demonstrate the feasibility of producing electricity at a cost of less than 1.5¢/kWh (based on maintenance, excludes biomass fuel costs) from a biomass resource with 98% or better availability. The plan was to achieve this by developing, installing and operating a 400kW Organic Rankine Cycle (ORC) power plant. The ORC power plant is be based on similar technology and hardware from the commercially available PureCycle® Organic Rankine Cycle (ORC) geothermal plant that is designed to produce 200kW of electric power from low temperature geothermal resource. However the new biomass power plant is to be designed with system efficiency close to 20%, representing over a 100% increase from the geothermal power plant. In addition, the new biomass power plants will be grid independent, which is significant for rural or remote areas including Alaska. This project also was proposed to validate the opportunity for Alaska to increase its renewable energy portfolio and decrease its dependence on expensive electricity generated with diesel engines using biomass as the primary fuel. To realize this opportunity we the team proposed to perform the following major tasks: C Design, purchase, fabricate and test a high efficiency ORC power plants ❑ Install and commission the ORC power plant to produce at least 400kW net power under nominal conditions using the thermal resources provided at the proposed site. C Demonstrate operability of the power plant The site chosen for construction and operation of the biomass power plant is located in North Pole Alaska at K&K Recycling ( Figure 1). Chena Power, the Prime contractor, is affiliated with K&K Recycling, and was responsible for procuring the biomass burner and integrating the plant. The burner consumes pellets made from recycled cardboard and other "woody" biomass (Figure 2) and produces a stream of heated thermal oil. The hot oil can be provided to the ORC system to produce electric power_ UTRC was contracted by Chena Power to provide the ORC part of the system. This final report serves as the final deliverable for this subcontract with Chena Power and provides an evaluation and demonstration of technology as well as recommendations for future work (outside scope of subcontract). UTC PROPRIETARY - Export Controlled - ECCN: EAR99 5 Fa rbaus �.i Et K&K Recycling Tanana River t Figure t: The Biomass site at K&K Recycling is located in North Pole Alaska (8 miles from Fairbanks) close to the Tanana River. Figure 2. Pellets produced by Chena Power from recycled cardboard. 1.2 ORC Option s ORC Power Plant (Background/Options/ Down -selected Technology) Previously UTRC has developed ORC power systems for use with geothermal resources. These systems were based on components derived from the Carrier 19XR product line. The 19YR turbine is a hermetic design (motor/generator shares refrigerant environment with compressor/turbine). The turbine is limited to an operating pressure of 300 Asia and a temperature of 330F. The temperature limitation results from the use of oil in the system to provide lubrication of the bearings. At higher temperatures the refrigerant -ail mixture can chemically breakdown. Since geothermal heat sources are generally lower than 30OF this temperature limit sloes not affect geothermal applications, however, since the hot oil produced by the biomass burner can reach 500F, limiting the refrigerant temperature to 330F significantly reduces the potential thermal efficiency of the system. UTC PROPRIETARY - Export Controlled - ECCN: EAR99 6 In order to achieve thermal efficiencies in excess of 20% different technologies were required to be developed. An ORC system needs a heat source and a heat sink. The thermodynamic potential is a function of the difference. Both air-cooled and water-cooled options were considered. Since the site is in a flat region close to the Tanana River Chena Power thought that cold well water would be readily available at a reasonably constant temperature throughout the year. In addition, water-cooled condensers are more compact and more easily integrated with the recuperators. For these reasons the water-cooled option was selected. 1.3 Innovative Technologies In order to fully utilize the thermodynamic potential of the biomass heat source and achieve thermal efficiencies in excess of 20%, different technologies were required then those available commercial off the shelf (COTS). UTRC developed a High -Speed Direct -Drive (HSDD) oil -free turbine/generator for this project. UTRC also developed a unique cascaded thermodynamic cycle which, together with the new turbines, would allow thermal efficiencies in excess of 20%. An inverter -based power electronic system was designed with grid -tie inverters that can pump current back into an existing grid at a power factor of unity. Finally, all the heat exchangers used in the system are flat -plate type which minimizes the volume of components and amount of refrigerant charge required, and all except the hottest topping cycle evaporator are brazed -plate which minimizes heat exchanger cost. 1.4 Statement of Work&Requirements The United Technologies Research Center (UTRC) shall lead a team to design, manufacture, test, install and demonstrate the performance, economics and reliability of a PureCycIe® Power System and demonstrate the feasibility of producing 400 kW net electric power from the biomass resource at an efficiency of 20%. Task 1: Project Management: UTRC shall conduct Project Management activities, including required report preparation and presentation and revised project management planning, in accordance with the requirements of the contract. Task 2: Cycle analysis and design point analysis UTRC shall define the design, point for the system based on data from the biomass source onsite. The optimization shall be driven to minimize total cost/kWh including parasitic loads such as cooling water pumps and the working fluid pump. UTRC shall perform a conceptual design of a high efficiency cascade cycle ORC power plant that shall employ a Siloxane topping cycle and a R245fa bottoming cycle. Task 3: Power Plant Specification UTC PROPRIETARY - Export Controlled - ECCN: EAR99 7 UTRC shall generate specifications for the overall power plant including electrical requirements, pressure drop requirements and material selection for heat exchanger tubes based on the resource analysis. Task 4: Component specification and design UTRC shall evaluate alternative components and control options with the goal of reducing the cost and improve reliability of the plant. This includes turbine stop and trip valve, turbine by-pass valves, pump and system control strategies and safety functions. The pump shall be selected to optimize cost and system performance. Task 5: Power plant design and fabrication The power plant design and fabrication consists of two subtasks: TASK 5A: Design. and Fabrication of Turbines and Heat Exchangers UTRC shall design and fabricate a total of five high-speed, direct -drive, oil -free turbines, two for the topping and three for the bottoming cycles. UTRC will also be responsible for the sizing and fabrication/procurement of the heat exchangers necessary for the cascaded cycle. The final arrangement for the system will be based on the heat exchanger size as determined at the design point. TASK SB: Power Electronics, Control Systems and Instrumentation UTRC shall 1) size and procure major components associated with the power plant's power electronics, 2) provide designs for the assembly of the power electronics, 3) provide controls for the power plant and magnetic bearings, and 4) provide instrumentation necessary for testing the performance of the power plant. Chena will be responsible for the procurement of the remaining electrical components and the assembly of the power electronics in cabinets required for connection to the grid. Task 6: Bench test of control logic at UTRC UTRC shall develop the system control logic based on their previous ORC products, and shall bench test this logic to provide for proper operation of the field units prior to field installation. The control logic shall be documented and incorporated into the final report Task 7: Site Installation and Commissioning UTRC, in cooperation with Chena, shall build and install the power plant. Chena shall be responsible for the connection of piping of heat source or heat sink to and from the ORC power plant. UTRC, in cooperation with Chena, shall commission the power plant. UTRC shall install the power plant along with the monitoring system. UTRC shall operate the power plant over its intended range of conditions and recalibrate and check all sensors with the system model. Task 8: Continuous operation of the power plant (Chena will be the lead on this task) UTRC shall provide support initially on plant monitoring and maintenance, as well as diagnostics and trouble -shooting. Technology and knowledge of plant operation and maintenance shall be transferred in written documents to Chena personnel. Chena is directly responsible for plant monitoring and maintenance. UTRC shall be responsible for diagnostics and troubleshooting. UTC PROPRIETARY - Export Controlled - ECCN: EAR99 8 2. Technology Description 2.1 Thermodynamic Cycles ORC systems deployed at low to medium -temperature geothermal sites are typically simple having only four major components (1. turbine/generator, 2. evaporator, 3. condenser and 4. refrigerant pump). However, the thermal potential of the biomass hot - oil system is much greater and requires a more complex ORC system in order to realize its potential. The following attributes characterize the biomass site: ❑ Able to achieve an oil supply temperature in excess of 500F. ❑ Able to have a high enough oil flow rate so that the leaving oil temperature in the evaporator is reasonably high and therefore an evaporator pinch condition is not a design limit. ❑ Sink temperatures are cool. There are various methods that can be used to fully utilize the large temperature potential available at this site: 1. Single cycle with large pressure ratio. This requires multi -staging of the turbine impellers and/or use of axial turbines. If a single refrigerant is used then there is a very large change is refrigerant density from inlet to exit of the turbine systems, and large condenser and recuperators. The combination of these factors leads to very expensive equipment. 2. Single cycle, highly superheated. A single refrigerant cycle which is highly superheated and employs a highly effective recuperator can achieve reasonable thermal efficiency. 3. Cascaded cycle: Two different refrigerant cycles are used. The heat rejected from the "topping' cycle is transfer to the "bottoming" cycle. It is also possible to add extra heat to the bottoming cycle. Given the desire to use less expensive single stage radial inflow turbines and to maintain minimum refrigerant pressures in the system at 1 atm or higher, the first option was not considered. Of the remaining two options the cascaded has the higher thermal efficiency and power output potential. The best bottoming cycle for a cascaded system alone can be optimized to achieve the same performance as the best single cycle option. 2.1.1 Cascaded cycle In order to obtain the highest possible thermal efficiency is achieved through the use of a cascaded cycle with two or more ORC cycles connected in series. The cascaded cycle uses two or more different refrigerants, a lower -pressure refrigerant in the topping cycle, and a relatively higher pressure refrigerant in the bottoming cycle. The condenser of the topping cycle is the evaporator of the bottoming cycle; that is, heat rejected form the topping cycle is a heat source to the bottoming. UTRC used their ORC design tool to examine various refrigerant choices and cycle configurations. Some of the refrigerant UTC PROPRIETARY - Exoort Controlled - ECCN: EAR99 9 choices considered are shown in Table 1 with their boiling point (temperature at 1 atm), critical pressure and temperature shown. Other cycle options consist of the degree of superheat for each cycle, and whether recuperators are used in one or both cycles, Table 1: ORC refrigerant properties. Refrigerant Boiling point (F) Critical T (F) Critical P (psia) R134a -15 214 589 R245fa 59 309 530 Novec649 121 336 270 Siloxane MM 213 474 281 Through this study it was determined that the best option is to drive both cycles to high superheat and to recuperate only the bottom cycle. The high turbine exit temperature from the topping cycle is used to heat to high turbine inlet superheat of the bottoming cycle. In this design, the heat exchanger that is employed between the topping and bottoming cycles is not a conventional condenserlevaporator. The topping cycle requires a de -superheater and then a condenser, while the bottoming cycle requires an evaporator and then a superheater (see Figure 3). It was further understood through analysis that only certain refrigerant pairs match efficiently since the relative amount of heat transfer in the saturated and superheated regions need to be similar. Another issue is that the power generated from the topping cycle is not independent of the power generated from the bottoming cycle since the heat available to the bottom is a direct function of the power and thermal efficiency of the top. Since the proposed generators to be used have a nominal capacity of 125kW, and only an integer number of generators can be used, it is desirable that the thermodynamic power available from each cycle be an integral number of 125kW. The ideal choice for the cascaded cycle was determined to be: 0 Bottoming cycle o Refrigerant: R245fa o High -superheat o Recuperated o Three nominal 125kWe turbine/generators ❑ Topping cycle o Refrigerant: Siloxane MM o High -superheat o Not recuperated o Two nominal 125kWe turbine/generators ❑ Heat -exchangers between cycles a De -superheater/ superheater o Condenser/ evaporator Figure 4 shows the PH and TS diagrams for the chosen cycle topping cycle, and Figure 5 shows the same for the bottoming cycle. UTC PROPRIETARY - Export Controlled - ECCN: EAR99 10 450 400 LL 350 a� 300 "E 250 ~ 200 150 0 Condenser/ Evaporator .................... Desu perheater / Su perh eater 05 1 Normalized change in enthalpy (counter fl ,-.o) Figure 3: Temperature as a function of normalized enthalpy through heat exchangers between topping and bottoming cycles. PH Cycle Diagram, Siloxane MM, TSCycle Diagram, Siloxane MM � I - - aso-� ' — - --- - ----- -; I i -50 0 50 10D 550 200 40 0"U, 11MY, 0 1)"...00 .J EnlhalPy(btuftm) Ent, ry Figure 4: PH and TS diagram for topping cycle, Siloxane MM. UTC PROPRIETARY - Exr)ort Controlled - ECCN: EAR99 l 1 PH Cycle Diagram, R245fa recuperated T5 Cycle Diagram, R245fa recuperated 1600.0 - .----- ----_ qpp t✓ -- _---.-- . _. ----------- -- -- -- ---------- - - - ---- --..__.---- _ ___----- -----------------,L.......... ... ..... 1,_.._—_II nn r, ' -------- -- -------- --....... - � ........ We--- -_-__ -._ - -�----?--r�---�--- - .. /f` : too r: 75 125 175 225 275:,(7p y gtyp Enthalpy(Blullhm) Entropy (Butlbm-R)) Figure 5: PH and TS diagram for bottoming cycle, R245fa Figure 6 shows the P&ID for the cascaded cycle. The primary components are listed in Table 2. The net power out of the system is 215 + 377 — 34 — 25 = 533kWe. The thermal efficiency of the system is 533/2,500 = 21%. Table 2: Primary Components for Cascaded Cycle Cycle Component Quantity Description Bottoming Turbine/generators 3 HST bearings, E&A generator, EPDM Refrigerant um 1 Sterling: CEHA6103 AAAF3 I 0 Receiver 1 Sloped pipe Condenser 3 3 paired with recuperator, each in parallel. SWEP #B427M2./280 plates Recuperator 3 3 paired with condenser, each in parallel. SWEP #B427M1/278 plates Topping Turbine/generators 2 S2M bearings and generator, Kalrez Refrigerant pump 1 Mag-drive version of Sterling # CEHA 6106 AAAF3 OA 0 Receiver 1 Sloped pipe Evaporator 1 API Heat Transfer Sigmawig ST40 TDL with wave compensators. Generator cooling 2 Consists of pump, heat exchanger, valves. Between Topping to bottoming HXs, condenser/eva . 2 SWEP #:V65M/188 plates Topping to bottoming HXs, de-sup/superheat 2 SWEP ##:B65L/278 plates UTC PROPRIETARY - Exhort Controlled - ECCN: EAR99 12 2.50MWt in -rr Refrigerant Piping, Cascade 377kWe a. outri _- 215kWe out 1.95MWt out, �4.6kWe in 4= ' Figure 6: Cascaded cycle P&ID. Bottom: 245fa, 3 turbines. Top: Siloxane MM, 2 turbines. The refrigerant used in the topping cycle, Siloxane MM, is similar to gasoline with respect to flammability and explosive potential. For this reason the piping and electrical components, including instrumentation, need to be different than that used in the bottoming cycle. The following design modifications were made to accommodate the explosive refrigerant. ❑ The generator casings were thickened to meet UL standards, where they were strengthened to be able to withstand the detonation of a stoichiometric mixture of Siloxane and air. In order to reduce the number of hardware components, this modification was done for all 5 turbines. ❑ The topping cycle components with Siloxane were to be placed in a shed attached to the outside wall of the main building. The shed was to be ventilated, and monitored for Siloxane leaks, o The Siloxane containing pipes were not to leave this shed. The HXs that have both refrigerants will be placed in the shed, and the R245fa pipes will penetrate the shed walls. ❑ All flanges for the Siloxane pipes were to be welded. ❑ All sensors and electronic feed-throughs must be explosion class. UTC PROPRIETARY - Exrrort Controlled - ECCN: EAR99 13 2.1.2 Bottoming cycle only In order to gain experience with the lower -risk bottoming cycle, a plan was developed so that the bottoming cycle could be run initially by itself To do this the condenser/evaporator of the cascaded cycle is replaced with a pre -heater evaporator which transfers heat from the hot -oil loop directly to the bottoming cycle. In fact, with this arrangement it is possible to run the refrigerant and cold -water of bottoming cycle at the same conditions as it would be running in the cascaded system, and produce 3/5th of the total generated power potential. The plan was to thoroughly qualify the bottoming cycle part of the plant before attempting to run the higher risk topping cycle with Siloxane. The pre-heater/evaporator of the bottorning-only cycle were to be piped in parallel with the condenser/evaporator of the combined cycle, thus allowing easy switching between the two cycle configurations. It should be noted that bottoming only cycle thermal efficiency is still fairly high since it is highly superheated and recuperated. It also should be noted that no major modifications are necessary to add an additional turbine/generator to the bottoming cycle (but as will be seen later some component changes are required to add a fifth.) Figure 7 shows the MID for the bottoming only cycle where a fourth turbine/generator has been added. The net power out of the system is 487 — 32 = 455kWe. The thermal efficiency of the system is 455/2500 =18%. Table 3: Primary Components for Bottoming Only Cycle Cycle Component Quantity Description Bottoming 3or4 ffSTlx;rrhig4. L' 'UNI l efi igcrant l Stcrlint- CI 1IAW 03 ."_ _ ' _ : ', 0 lLeccivc�" 1 Slei;�c._� _-��-•u Concicr�scr , �ti��':. ; ���it1� : . ^ •- . .. ;;� . ... ". '13427.-. 2 L,.) 3 ..... , 27M1;1 7> p1.i.1.1 Pre -heater I SWEP #B50L/106 plates Evaporator 2 SWEP #:V400T/224 plates UTC PROPRIETARY - Export Controlled - ECCN: EAR99 14 kW Ot. 00 . f 'Y"TY'• Figm-e 7, Bottoming only MID. with 2.1.3 Hot Oil system and control. The biomass heater provides hot oil to the three-way valve system would be used to e i Evaporator Biomass 8umar BV 255 f— Mixing umn Figure 8: Hot -oil loop and control. 2.2 HSDD (High -Speed Direct -Drive) turbine/ generators The key component of the ORC system is the turbine/generator. The turbine/generator used in a geothermal power plant is not suitable for the topping cycle of the high - efficiency biomass plant due its higher temperatures. For the biomass system UTRC designed and developed a new turbine generator with the following features: ❑ 125 kW gross power capability ❑ Oil free: No concerns with oil high -temperature break -down ❑ Direct drive, magnetic bearings: no oil required ❑ High-speed (28,000 rpm) permanent magnet generator: good power density The turbo -generator component combines a direct drive radial inflow turbine with a synchronous generator in a single hermetically sealed unit. Generator cooling is provided by the working fluid. The single -stage radial inflow turbine is the most cost effective turbine design possible. The turbine can be specified with a rotor/stator and multi -port conical nozzles chosen from a range of standard options to provide the optimal performance for specific design points. UTRC developed two slightly different HSDD designs. One was based on generator and bearing components supplied by S2M (a French based subsidiary of SKF), and the other was based on generators provided by E&A and magnetic bearing provided by HST. Three HST units were produced and configured for the bottoming cycle of the biomass power plant, and two the S2M units were produced and configured for the topping cycle. Table 4 lists the key attributes of the two designs. UTC PROPRIETARY - Export Controlled - ECCN: FAR99 16 Table 4: Turbine/generator attributes Tli-ermo. Cycle Num. Generator manuf. Poles Mag. Bearing Manuf. Refrigerant 0-ring material Bottoming 3 E&A 4 HST R245fa EPDM Topping 2 S3M 2 S2M Siloxane MM Kalrez Figure 9 shows the drawing and production unit for the HST version. Figure 10 shows a cross-section of the HST version, and Figure 11 shows a cross-section of the S2M version of the HSDD turbo -generator. 2.2.1 Refrigerant and seals Since the refrigerants used in these two cycles are different class fluids, different O-ring materials are required for each set. R245fa is an HFC (penta-fluoro propane) whereas siloxane MM's formula is (CH3)3SOS(CH3)3. The O-ring materials cannot be mixed between applications; EPDM will not survive the higher temperatures of the topping cycle, and R245fa will dissolve Kalrez. The turbines currently configured to run siloxane can be disassembled and rebuild using EPDM seals per assembly/disassembly instructions in Appendix A 2.2.2 Generator Poles and required inverter frequency. The number of poles in the stator winding of the generator affects the frequency of the power between the generator and 'inverter, and therefore the design of the inverter and that of the sine -filter that goes between them. For a 2-pole motor the electrical frequency is the same as the speed of the generator; for a 4-pole it is twice. Table 5: Electrical frequency with turbine operating at 28,000 rpm. Poles FrecLelect. (hz) Bottoming 4 467 Topping 2 933 1A UTC PROPRIETARY - Export Controlled - ECCN: EAR99 17 Figure 9. HSDD (High-speed direct -drive) turbine/generator drawing and prototype unit. Stator PM Refrig. (4pole) rotor Cooling Mag. Bearing (axial) Volute Mag. Bearing" Mag. Bearing (radial)kl_:�71ATA (radial) Figure 1.0: Schematic of HSDD turbine/generator, HST bearing design. Refrig. Stator PM Cooling (4pole) rotor Mag. B (axial) Nozzle Impeller Volute r Nozzle Impeller diffusor e Mag. BeaffM_ (radial) Figure 11: Schematic of HSDD turbine/generator, S2M bearing design. 2.2.3 Cooling and thermal management The cooling method for the bottoming cycle and topping cycle turbines is different. For the bottoming cycle the method used is based on the successful method used on the UTC PureCycle 280kW geothermal units. High pressure liquid is bled from the primary refrigerant loop after the pump and before it is heated in the recuperator. This liquid is UTC PROPRIETARY - Exoort Controlled - ECCN: EAR99 18 metered. to a port at the base of the cooling jacket (see Figure 9 and Figure 10). After picking up heat from the cooling jacket and stator, it leaves the unit and is split into two separate streams. The streams are fed back into the casing at the void between the stator and magnetic radial bearings. Nozzles spray the refrigerant into the voids. The flow rate reeds to be such that the heat provided by the cooling jacket is sufficient to partially vaporize the fluid so that a vapor -liquid mixture is fed to the nozzles. This mixture sprays out into the cavity cooling all the components including the rotor. Drain ports are provided at the bottom of each side of the casing. The casing is designed to be at a pressure that is slightly higher than the backing plane of the impeller. The impeller has bleed ports that lead from the backing plane to the discharge (diffuser). There is a small net flow of refrigerant vapor from the generator casing through the labyrinth seals on the impeller shaft to the impeller backing -plane and out through the bleed ports. The temperature of the refrigerant cooling the rotor and bearings is the saturation temperature of the refrigerant in the generator casing (which is slightly above the primary loop condensing pressure). For the bottoming cycle this is less than 100F, but for the topping cycle this is —240F, which is too warm. A different method is needed for cooling the topping cycle generators. Figure 12 shows a schematic of the system devised. A secondary heat exchanger is cooled by bleed stream form the condenser water loop. By condensing Siloxane in this heat exchanger the pressure of the generator section is pumped down to less than the main -loop condensing temperature. The liquid refrigerant from the heat exchanger is collected in a receiver that feeds a small gear pump. This pump circulates the liquid through the same cooling jacket and spray nozzles as are used for the bottoming cycle. To achieve 120F saturated temperature with Siloxane the required pressure is 2.4psia. With the generator cavity at sub -atmospheric pressure refrigerant that gets through the two labyrinth seals: 1) on the back of the impeller and 2) on the impeller shaft, will make its way into the generator cavity. To prevent hot refrigerant from reaching the generator cavity the shaft seal was split into two with a gap machined between the two seal sections. A port was placed so as to bleed the refrigerant vapor directly to the small condenser and prevent net migration of hot vapor from the impeller backing -plane directly into the generator cavity. Since there is net flow of refrigerant from the main loop to the generator cavity through the impeller labyrinth seal, refrigerant will accumulate in the condenser/receiver and eventually flood the condenser preventing further condensation. With reduced condensation the pressure (and temperature) in the generator cavity will rise. The control system will monitor this pressure and increase the gear -pump speed as the pressure rises. A higher gear -pump speed will raise the pressure in the lines that connect to the cooling ports. A resistance may be added to this line so that the pressure at the pump exit can exceed the condensing pressure while the pressure in the cooling jacket is lower. As the pressure exceeds the condensing pressure, a stream of the refrigerant flows back into the main -loop before the primary refrigerant pump. In steady-state the refrigerant flowing out must equal that leaking in. UTC PROPRIETARY - Exhort Controlled - ECCN: EAR99 19 Heat sours Gaoling Water Pump Figure 12: Generator cooling plan for the topping cycle. 2.3 Magnetic Bearings Magnetic bearings systems were provided by two different manufactures. For the bottoming cycle three systems were provided by HST. For the topping cycle (or remaining two generators) two were provided by S2M. The bearing systems consist of two radial bearings, one axial bearing, bearing control modules and power supply systems. The radial bearings can, in fact, support some axial force, but it was determined that extra support was needed due to the variable nature of the turbine thrust load at different operating conditions. The power supply contains battery backup which ensures that the bearings can continue to operate in the event of a grid -failure. 2.4 Power Electronics 2.4.1 Hardware Figure 13 shows a one -line diagram for the ORC power plant. Table b lists the primary power components provided by Vacon. The key attributes of the ORC electrical system are: 1. The power system, shown in the large green box on the right side of Figure 13, consists of modular components provided by Vacon. Each component attaches to the DC bus and has its specific task as described below. a. The grid -tie inverters maintain the set voltage on the DC bus. If the voltage is low they will draw power from the grid. In normal operationn they take power from the bus and put it on the grid. They follow the existing grid voltage signal and pump current at a prescribed power factor (nominally 1). b. A charging circuit (not shown) is used to activate the system. The startup procedure is described below. c. The LCL filters go between the grid -tie inverters and the grid. They remove higher harmonics produced by the grid -tie inverters. d. Each generator is matched to an inverter. These inverters effectively control the speed of the generators by either taking power from the DC bus or putting power into the DC bus as necessary. In normal operation power goes from UTC PROPRIETARY - Exnort Controlled - ECCN: EAR99 20 the generators through the inverters to the DC bus. The generator startup procedure is described below. e. Between each generator and inverter is a sine -filter to remove higher harmonics produced by the inverters and reduce heating of the stator windings. f. Each of the two refrigerant pumps (bottoming and topping cycles) has an inverter which controls its speed. In normal operation power goes from the DC bus to the pump motors. The speed set -point is sent to the inverters from the system controller. g. A brake inverter is attached to a 2.2ohm resistor (heat sink). Its job is to dump power should the DC bus exceed a certain pre-set value. Normally this inverter is inactive. In the event of a grid -trip, when the grid -tie inverters cannot move power from the DC bus to the grid, the DC bus voltage rises and this inverter activates. The grid trip event triggers a shutdown of the turbines so this event only lasts a few seconds before no more power is generated. 2. The system controller is provided by a separate source of single phase 120Vac. A UPS system ensures that the controls can remain active during a grid -trip, although safety interlocks will shut down the system even if power is lost to the controller. 3. The bearing controllers are provided with a separate source of 480VAC. 4. The ORC plant requires several other external components: pneumatic air, hot oil circulation pump, and cold water circulation pumps. UTC PROPRIETARY - Exuort Controlled - ECCN: EAR99 21 f'S E RI•pl ORC Ram [2X] A [2X] B ORC Aux.:,ry } .. .... . 71VVV [2X] D F R.�... `.Z: h.e 26tr 87A1117A } T tj j # • • • • 9 BrdkB �'� •, •�4 ttt [1XI E '•.l.li2......... €E� [3X] G L,.__ .. L 4 4 75F9� 75HP .�R .yr F' r. _ •,tv,•Lr C. € Gt.••'f '.r (� - or .. G9••er3'L% :,6nfilfi'..R 49, 25 kw 72Swri 125 s.10 -HP et' A � A 950A ;-,IA S2M HST/E&A Figure 13: One-Iine diagram of ORC power plant. Key power components labeled A-G, provided by Vacon, are referenced in Table 6. Table 6: Power electronics key co m onents provided by Vacon. Label Quantity Function Part Number A 2 LCL filter Vacon#LC©-460-5-A-0-R-0-1-1-T B 2 Grid -tie inverter Vacon #NXA-460-5-A-0-T-0-2-S-F-A1-A2- B5-D2-C1 C 5 High frequency inverters for generators Vacon #NXi-0261-5-A-0-T-0-1-S-F-Al-A2- 00-D2-C D 2 Inverters for refrigerant urn s Vacon # NXI-0087-5-A-2-T-0-C-5-S-S-A1- A2-00-D2-Cl E I Brake Inverter Vacon #NXB-0460-5-A-0-T-8-F-Al-A2-00- D2-0 F 2 470 Hz sine filters - G 3 930 Hz sine filters - 2.4.2 Startup of the Power system Before power up the DC bus will be discharged and the breakers to the LCL filters will be open. The power system is activated by the user enabling the charging circuit. The charging circuit draws power from the grid to charge the DC bus. During this time the Vacon inverter control modules are active. The grid -tie inverter monitors the DC bus and UTC PROPRIETARY - Exhort Controlled - ECCN: EAR99 22 when it reaches a prescribed value closes the main breakers. The charging circuit is then disconnected from the DC bus. 2.4.3 Startup ofthe generators The control system first runs the ORC system with the turbines in bypass mode. Each turbine is paired with a bypass orifice which roughly matches the size of the nozzles in the turbine. A pair of valves is used to either open flow to the turbine or to the bypass orifice. The bypass valve is normally open and the turbine inlet valve is normally closed. When the system controller determines that it is time to switch from bypass mode to turbine mode it first requests that the inverter bring the turbine up to speed. This motoring requires power to flow from the DC bus to the "generator." After a few seconds and the confirmation signal is received from the inverter that the generator is up to speed, the controller closes the bypass valve and opens the turbine inlet valve. The turbine/generator then produces power which is transferred to the DC bus by the inverter. 3. System Installation and commissioning 3.1 Installation of bottoming cycle UTRC subcontracted with Chena Power to build the ORC plant. The contract covered the build of the components, the power electronics and bearings -controllers. Three visits were made by UTRC personnel to the biomass plant site to assist with the build and commissioning: I . Summer 2010: Inspect equipment sent to site, go over installation contracts. 2. December 2010: Assist in instrumentation and control wiring, Review construction. 3. February 2011: complete bottoming cycle and commission. The following pictures were taken after the final February 2011 visit. Figure 14 shows the ORC plant with a view of the control and power panels. The turbines are located on a raised platform behind the power panels. The platform continues to the right where the condensers and recuperators are located. On the far -right of this platform (not visible) are the evaporator and pre -heater. The hot oil enters the room from the top -right. The adjacent room houses the burner/hot-oil heater. On a raised platform over the evaporators are the oil control components consisting of the ORC oil pump and control valves. UTC PROPRIETARY - Exoort Controlled - ECCN: EAR99 23 Turbine platform Condenserslrecuperators Hot -oil control Figure 14: View of ORC plant Figure 15 shows a view looking down the main platform from the turbines towards the condensers, recuperators and evaporators. Each condenser is paired with a recuperator. The three condenser -recuperator pairs are piped in parallel. The cold well water enters the condensers on the bottom and leaves from the top. There is a large header running under the platform that receives hot low-pressure refrigerant vapor from the turbines. There are a total of six 4" connection pipes from the header into the bottom ports of the recuperators; each recuperator has two vapor inlet ports, one on each side. There are also a total of six connection pipes that take cooled low-pressure vapor from the recuperator to the condensers at the top of the units. The condensed refrigerant vapor leaves a single port from the bottom back -side of each condenser (not visible). The high-pressure refrigerant liquid enters the recuperator from the top -back port and leaves from a bottom back -port (not visible). UTC PROPRIETARY - Exvort Controlled - ECCN: EAR99 24 Condenser water out Vapor from recuperator to condenser Condenserwater in Hot vapor from turbine exhaust to recuperator Figure 15: View down platfonn showing condensers, recuperators and evaporators. Figure 16 shows the top platform and oil control components. The ORC oil circulation pump rests on the platform, and the two variable pneumatic valves are visible. The oil is circulated from the pump exit to the two evaporators (in parallel) and then through the pre -heater which reside on the lower platform directly underneath. Figure 17 shows the main platform from a view next to the upper platform. The three turbines are fed hot high-pressure refrigerant vapor from the evaporators through the turbine inlet valves. Alternately the vapor may be bypassed around the turbines directly into a large header that runs underneath the platform. Although three turbines are currently installed, there is room for at least one more at the end of the platform. UTC PROPRIETARY - Exnort Controlled - ECCN: EAR99 25 Figure 16: View of upper platform showing oil control components. Hot high-pressure refrigerant vapor from evaporators to turbines. Figure 17: View of main (lower) platform looking from heat exchangers to turbines. Figure 1$ and Figure 19 show the left side and right side of the power panel. The Vacon LCL filters reside on the far left and tie directly to the breakers that connect to the grid. The UTC PROPRIETARY - Export Controlled - ECCN: EAR99 26 beakers, not shown reside in the compartment underneath the System control panel. Rive Vacon inverter sub -components are contained in the left power panel. From left to right they are the two grid -tie inverters, the brake inverter, and the first two generator inverters for turbines I and 2. The right power panel houses the other three Vacon generator inverters (although only one of them is currently being used for turbine #3) and the two refrigerant pump inverters (although only one of them is currently needed for the bottoming cycle). Also contained in the right power panel are the HST bearing controllers for turbines 1 through 3. On the far right of this panel are the sine -filters for turbines 1 through three. The S2M bearing controllers and the corresponding 2-pole sine -filters have not been mounted. The topping system with Siloxane was to be installed in a vented shed next to this building located through the far -right wall ( Figure 14). The cable length for the bearing controllers is limited and therefore another power panel would have been needed closer to the topping cycle turbines. Grid -tie Inverters Generator inverters (1 &2) Figure 1S: Left side of power panel. UTC PROPRIETARY - Export Controlled - ECCN: EAR99 27 HST bearing controllers Bearing backup power Refrigerant pump inverters Figure 19: Left side of power panel. Figure 20 shows a picture of the ORC control panel before it was installed in the power plant and wired to the sensors and actuators. The functional component groups are labeled. UTC PROPRIETARY - Exhort Controlled - ECCN: EAR99 28 PrimaryCC6400 W. I 24VAC supply to be switched to each cooling programmable � solenoid. controller t Additional UO 24VAC supply to be than nelsforthe , = switched to each bypass controller r and turbine valve solenoid Bypass valve override switches 5V DC source for TI pressure r ,~YLORrelays. transducers. 1 0 1 Connectionsfor external bearing and Ground rectifier okay logic 24VDC source forthe following: " Bearing and rectifier okayrelays 1. Mode switch &cuits 2. LOR (Lockout Relay)chain Watch Dog Timer relay 3. Source forOmega RTD sE:. conditioning modules 4. Source forextemalbearing and inverter/reo fierokay x; switches. Interface relays between CC6400 programmable CC6400 and: Omega RTDITC control ierfo r extra 1. MotorcooJng conditioning diagnostic sensors. 2. Bypass/turbinevalves modules Extra I/O module 3. Turbine/recffierON 4. Bearing ON Figure 20: Control Panel (before integration) 4. Recommendations 4.1 Topping cycle risks UTRC held a design review that involved the project team, senior management and a technical fellow. UTRC reviewed the initial data from bottoming cycle operation with 3 turbines. UTRC then developed recommendations about the course of action needed to implement all five turbines in the combined cycle to generate 400kW of net power. The recommendations were communicated to Chena Power. At the time of the review there were still several outstanding issues with the bottoming cycle. 1. Bearing for turbine #1 was tripping on startup. 2. All turbines running at lower speed to prevent overheating. 3. Turbine 1 overheating even at reduced speed Before testing of the bottoming cycle the top risks that had been identified for the complete cascaded cycle implementation were all related to the topping cycle: 1. siloxane flammability and potential explosion UTC PROPRIETARY - Exhort Controlled - ECCN: EAR99 29 2. Topping cycle generator cooling, 3. Topping cycle thermal management of turbine -generator interface, and 4. Control of the cascaded cycles such that the intermediate pressures are maintained through transients at a level which balances the power output of the topping and bottoming cycles to acceptable levels. Given the unresolved problems with the bottoming cycle the UTRC team communicated to Chena Power that a more cost effective, less risky and timely approach to activating all five turbines would be to resolve the bottoming cycle issues and implement a non - cascaded single cycle with all five turbines on the R245fa cycle. Chena Power concurred with the recommendations since there was a clear path to 400kWe of net power. It should be noted that the total power output potential of the ORC system is not necessarily a function of which cycle option is chosen. It is possible to operate all five turbines in a single R245fa cycle at full power, and the parasitic powers will be similar. The difference is in the thermal efficiency of the system. Lower thermal efficiency requires more heat from the oil burner for a given power output. However, the bottoming only cycle is still highly efficient (18% compared to 21%). By avoiding the Siloxane based topping cycle the following high -risk issues will be avoided: ❑ An all new generator cooling scheme never before tested ❑ Costly electronic and sensor explosion class installation, ❑ Thermal stresses in the turbine with new 0-ring seals (Kalrez) not fully tested in this environment. ❑ Eliminate the need to construct a separate building to house the topping cycle ❑ Reduction in the required piping and installation to be provided by Chena Power The following sub -sections describe the work that was done to assess the feasibility of going to a 5 turbine single -cycle implementation. The first sub -section shows the thermodynamic sizing calculations, and the second addresses each of the key components. 4.2 Thermodynamic analysis of 5-turbine bottoming cycle The desired thermodynamic cycle for a bottoming cycle with five turbines is the same as with three, but consideration needs to be given that ❑ The cooling flow is sufficient. ❑ The hot oil flow is sufficient, and Operating condition to get full power from each turbine: Tsat_low = 80F (23 psia) Tsat_high = 215F (190 psia) Pr = 7.8 Turbine inlet superheat = 100dF (315F) Generated power = 120 kW X 4 = 480 kW UTC PROPRIETARY - Export Controlled - ECCN: EAR99 30 Refrigerant Pump power = 25 kW Oil pump at 252 gpm. Should be doing at least 400 gpm, but data indicates about 220gpm. May need to raise inlet temperature further to compensate. 450 HUI 350 r 00 �50 �00 p 50 M ?100 50 020 030 0.40 050 Entropy (Btu1(1brn-R)) 1000.0 cv C 1000 a) N �l 100 50 100 150 200 250 Enthalpy (BtuAbm) Figure 21: T5 and PH diagram for single R245fa cycle with 5 turbines The gross power output is limited by the capacity of the five turbines: 5 X 125 = 625kW The net plant power is this value minus all parasitic power of the 1) refi7gerant pump(s), 2) Condenser water well pump, 3) Oil circulation pump, 4) ORC power electronic losses, and 5) oil -heater power. The refrigerant pump power is estimated by the ORC design code. (Note that the motors for the refrigerant pumps are considerably oversized at 75HP; this is not the expected power under any operating condition.) To meet the 400kW plant output the sum of the parasitic powers must be lower than 225kW. Table 7 lists the estimated parasitic powers. The oil -heater is estimated at 100kW. The net plant power is estimated to exceed 400kW_ Table 7: Calculation of parasitic power Component Power Comments Oil heater 100kW Estimate Condenser well pump 19kW 500 gpm at 100 ft head, at 50% efficiency Oil circulation pump 4kW 400 Sprn, at 20 ft oil head, at 50% efficiency Refrigerant pump 50kW From ORC code, using Sterling CEH6106 pump curves. Power electronics 38kW 6% of 625kW Total 1 211 kW 4.3 Analysis of components and recommendations UTC PROPRIETARY - Export Controlled - ECCN: EAR99 31 The following sub -sections discuss each primary component with respect to modifications required for the use in a bottoming only cycle. 4.3.1 Turbine -generators UTRC does not see any issues with using the two additional turbine/generators (of the topping cycle) in the bottoming cycle. The S2M bearings are capable of running in either refrigerant environment, and the rating of the power components is the same. In fact, even the aero-design of the turbine (nozzles, impeller, shroud and diffuser) are identical. However, it is necessary to change all the O-rings from Kalrez to EPDM since Kalrez will dissolve in a HFC environment. Appendix A provides step by step instructions for disassembling and reassembling the turbine with different O-rings. 4.3.2 Condensers and recuperators Initial data indicates that the condensers are oversized for three turbines in that they produce a good deal of sub -cooling at a condensing temperature that is very close to the leaving water temperature. They should be able to handle the additional refrigerant flow with a slight increase in approach. It is more important that the condenser water flow be increased. The initial data does not allow for determining the recuperators' performance. This is because there is too much cooling flow through the generators, and the turbine exhaust has little or no superheat. 4.3.3 Evaporators and pre -heater The current evaporator/preheater is meeting it target performance in that the approach is within 10F. Increasing the flow will increase this to —15F, but this small difference can be made-up for by raising the oil temperature by an insignificant 5F. It is more important that the oil flow rate be increased (see below). ❑ The evaporator is currently running at only 280F. This generates a pressure ratio of 8 and a high -side pressure of Tsat —195F, but at only 5OF superheat. ❑ The temperature limit for the brazed plate evaporator is 425F. The oil inlet set point can be increased to 40OF with sufficient safety margin. This should significantly increase the heat into the ORC system. 4.3.4 Refrigerant Pump The current pump in the system is capable of providing refrigerant flow for up to 4 bottoming cycle turbines, but not 5. However, the pump that was to be used for the topping cycle has more stages and therefore a slightly higher capacity than that for the bottoming. (Even though the topping cycle has Iess refrigerant mass flow, since Siloxane is significantly less dense than R -45fa, the volume flow is similar and a pump capable of greater "head" is required.) ❑ Initial data indicates that the refrigerant pump is meeting its design performance. UTC PROPRIETARY - Exnort Controlled - ECCN: EAR99 32 ❑ It is recommended that the current refrigerant pump be removed and replaced with the other "topping" cycle pump. The distance between inlet and outlet ports is greater and some piping will also need to be modified. 4.3.5 Oil Circulation pump The initial data indicates that the hot oil pump is underperforming. Figure 22 shows the manufacture pump curves for the product line. The specific pump, 080-160, should be producing >400 gpm of oil flow at 40 ft of head.. Energy balance from the initial data indicates that only 220 gpm is being produced. Although acceptable for three turbine operation, five will require full flow. The oil -pump flow issue needs to be diagnosed and resolved. During the commissioning trip the team looked into oil loop pressure drop and found it to be very low (much less than 40ft) indicating another issue with the pump. m 10 20 #0 60 E0 I00 WD A k SW 1000 TSW M WO !RV mn �.-.L..-.-- t x e! ! s i U49 'D 2R 40 60 ao i00 2T 400 6C4 §JD 17DD ISW 2005 11M !T M%00 04015 W$16 �3225D q65, - s-iN 5 25G 7W YZS t5D- ' 66 =200A on 30 OBR � AQ ; NOB 200 BOA 20�0 I 2n . 25- 632750A 032. d10' 066 C.: 'kf i40B JW Wd 1S0 W . 00 E6 h321 e'S 15 riq� Z9 iZ5 N rs 2➢ I f; I t07 .. ibl i ?DOIi Figure 22: Manufacture data for oil pump. Model 080-160 should produce 400gpm at 40ft of head. 4.3.6 Power electronics and bearing controllers The generator inverters and sine -filters depend on the generator not the refiagerant environment and do not need to be modified. These components were to be mounted next to the Siloxane shed on the back wall of the ORC room, but now may be mounted closer to the existing power panel. ❑ Note: in either plan it is necessary to involve S2M (the magnetic bearing supplier) in the tuning of their bearings. 4.3.7 Valves Only three sets of turbine -inlet and bypass valves where initially purchased for the ORC system. The intention was to use the bottoming cycle to ensure that these valves were adequate for the high -temperature application. Two new valve sets need to be obtained for the extra two turbines. This would have been true for the Siloxane system as well, UTC PROPRIETARY - Exhort Controlled - ECCN: EAR99 33 although explosion -proof electronics would have been required for the 24Vdc activation signal to enable compatibility with Siloxane. 4.3.8 Sensors and VB monitoring code Implementing all turbines on the bottoming cycle reduces the number of required sensors, and eliminates the need for explosion class sensors. The VB monitoring code was initially written assuming that we would be transitioning to a cascaded cycle. A new VB code has been written for the 5-turbine bottoming only cycle. Figure 23 shows the sensor modifications. As a result a number of channels will be inactive. Other sensor changes required include: ❑ The cycle needs to be run a higher temperature to get full power from the turbines. The existing pressure transducers that are downstream of the evaporator and upstream of the turbines should be remounted to avoid overheating. It is recommended that they be mounted from a'/" tube that is hanging down about 5 inches from the main line. This line will fill with liquid refrigerant and will allow the transducer to be cooler than the refrigerant and main pipe. ❑ Each inverter should provide power information to the system controller. This requires establishment of a 4-20mA signal from each Vacon unit and running a wire to the control panel. 4.3.9 System Controller The existing BEST code residing in the system controller has the IO for the cascaded system, but its close -loop algorithms are suitable to the bottoming only cycle only. Implementation of the cascaded cycle would have required code additions and modification. A new BEST code for the system controllers has been written to for the 5- tubine single R245fa cycle system. The extra turbines are brought on line in the same manner as the first three. The pump control logic will need to be adjusted to accommodate the different refrigerant pump and additional flow. In addition the following modifications were made. ❑ Sensor location and list made to match changes described in the previous section. ❑ Better protection for oil temperature to evaporator. Temperature must not exceed 435F at Oil In. Shut off circulation pump if T>435 for xx seconds. ❑ Logic added to use Inverter power as indicator of whether a turbine is running. UTC PROPRIETARY - Exbort Controlled - ECCN: EAR99 34 fNPUT CHANNELS: OUTPUT LHAMNELS. Cwsd EWT 1- ! " - 50 -.. I Nnf Umd 1: 0 Cand LWT 2: 70 Turbi—Vahest 2- I 0 Od Leavinp T 3: 1 45U - Gen Cooling 1 3 ➢ ` Ail Enlerimg T 4: Not Wed + �— 0 Wiadi" 71 5Z j 3!1 �I I TusbineNAly `; Wwtdiag T2 G: 12A Gen Co kg 2 6: p Winding T37 ".`"'-34➢ :I Hal Used 7: 0 "� 0.11 Set Paint $: "� 100 __ I TodxineNalves3 $-' 0 5H 5el Faint S __1 -„j Gen Cn.EM 3 9: T_ �E�ap EsdT OaE1R 11➢ Not Used l➢: - 0 I Evap Ekiti T�p i4; i' 1513 :_.; �Tu.bine Yal4 11;- Hyg}r Prm Sot 12: 120 .� Qen Cecri g 4 12: High Pre, Tap 13 '� IOU --� Net used 13: 0 30 L. LoK Frei 7oP 16- 30 _ ! - Turbine Vafires514: 0 - Gan CooYeg 5 46: p Condensate Rat TO: 00 .- Quin Line 1 R: Software Channels -- Rai. Trine - 1T�-•- Num cam. f k Rrur5laie � � � -- 5uh-stale irrleu � .� Evap F-AT it 1 , L wve.Exu1T tap i-7 1— Ev4p Tset but 1 L Evap Tsai tap —Evap SH bat � T L_Evva SH P -.. AlariNu 1 .J.... Power sMFt 1 Condensate Tap 17: OU _! Card Pranp ON 17_ Gerusat. P4It 10 �" Cofd Pump (Hs)10L .I Genaratol P51So, — IS GenCaaf4 [Hz]i9:I� 0 1 Ga_era SAC z r Ref Puwp1 AN 21 _-__......0__...__. - . Rat P w2 QcWL2 p _ _ Rat N.PICRZj 22: ----- AFE1 jkWj 23. j 30 .J I Ref P', QN 23 jjI- 0 _ Heat AvAabta 24: �_. AFEAMI OK 26: , 1 -•-• - i Heat An 25: i 0 �� Hearlrgl OK24` f1ea1X 1s129'_ -. •.,•..._ i i eeadnoz AK 27: Heatx 2nd 27: ➢ Rearxg3 QK 2>i T — Watch Dag 23: -- ➢ Searirg4 OK 29: BeasingS OK 30: t Enb3/+eset 29: 0 ; .. .....—_ na1 used 31k net used 31! i— not used 32: i ➢ ..�. r.' CCN allowed 31: Mode Input 32, ➢ �..~_:"--iS. Uatakegm�ilion Condaf �y� Slml New ' SinylaRead-- ,, Fte Figure 23: VB monitoring code screen with sensor changes highlighted. 4.4 Outstanding items This section summarizes the outstanding issues relating both to getting the existing bottoming cycle up to full power, and to adding two additional turbine/generators to the bottoming cycle. Outstanding issues with the Existing Bottoming -cycle: 1. Generator cooling diagnostic plan implemented, inverter supplier Vacon engaged and cooling issue resolved. 2. Turbine speed issue. The PM generators are constant torque devices and their power output capability is proportional to their speed. Full power requires that they are able to ran at full speed and power without overheating 3. ORC system controller needs power feedback from all five generator inverters. 4. Operability of turbine inlet and bypass valves Recommended actions for adding two turbines: 1. Retrofit 0-rings from. Kalrez to EPDM on current topping cycle turbines per procedure in Appendix A UTC PROPRIETARY - Export Controlled - ECCN: EAR99 35 2. Mount turbines and pipe to existing headers. 3. Purchase and install additional set of valves 4. Wire valves to control panel, connectors exist. 5. Determine if the 24Vac transformer supply to valves is it large enough for 5 sets 6. Power wiring from existing inverters to new turbines. 7. New bearing controllers (S2M) mounted, wired to bearings. Interlock wiring to control circuits same as other three, connectors exist in control panel. 8. Commission S2M bearings: S2M representative required to go to Fairbanks. 4.5 Summary The ORC Electrical Power System for Biomass Application project was conducted over a three year period. This represents more than 18 months longer than originally planned. The major milestones in the final project timeline is shown below Statements of Work to K&R Fbquest from Chena Fbwer to assist Begin shipping to construct elan# in starting turbines 1-3 for AEAdemo componentsto K&R r-- Control Fbview I Cooling test plan (not completed; Vacon partsat Vaoon plant 1 1 Commissioning trip #2 UTRC visit Installation L Commissioning trip #1 review trip Figure 24: Project Timeline UTC PROPRIETARY - Export Controlled - ECCN: EAR99 36 Appendix A Turbine Hot Section O-Ring replacement procedure The topping cycle (S2M) turbines were originally intended for use with high temperature Siloxane. The operating temperature exceeded the capability of the Parker EPDM used for ORC applications at UTRC in the past so the hot section of the turbine has been built using DuPont Kalrez 0-rings. To be used with R245fa the Kalrez rings has to be replaced with Rings fabricated from Parker E0962 90 Shore. Figure 11 shows the location of the O-rings needing replacement. O-rings in positions 19, 22, 24, 25, 26 and 27(3 places) needs to be exchanged to Parker EPDM :E-' : �. f-A _. Figure 24: Location of Kalrez O-rings needing replacement. UTC PROPRIETARY - Export Controlled - ECCN: EAR99 37 s IS . A t - -)66 � 5 54 A8 ` 3778 M AS568 - w. O-Ring sizes. Disassembly Procedure To disassemble the turbine it needs to be st is to stand the turbine on a minimum of 4 tl long nuts allowiniz for the turbine to be lei-, allow for no more than l'4 clearance tinder has to rigid enough to support the weight m disassembly assembly requires a crane engine hoist or similar crane is not recomr, Flprtrir rr rvpv z hqQ try lip xvitl Figure 26: Orientation of turbine during disassembly/assembly. Disassembly process Figure 3: Mark location/indexing and Remove discharge Housing (5) UTC PROPRIETARY - Exoort Controlled - ECCN: EAR99 39 Figure 4: Remove the bolts holding the nozzle. Mark location and remove nozzle and inlet screen assembly (7, 11, and 17). It might be required to use jacking screws or to use two bars across the face of the housing together with threaded rods and spacers to overcome initial friction in the O-rings. Figure S: Mark location and remove the volute (2). Be careful not to swing the volute so that it touches the impeller. UTC PROPRIETARY - Export Controlled - ECCN: EAR99 40 Remove impeller bolt (' 9) and replace it tE the top of the impeller. Note that there are and HST turbines. This bolt is used to reac Figure 6.- Make a mark on the impeller in j puller with 4 screws into the lace onhe 1111 and use screws and washers that provide rig Carefully mark the location of the balance Install Procedure Install in opposite order. Use Loctite 242 on impeller bolt and all internal fasteners. Torque impeller bolt to 60 ft-lb UTC PROPRIETARY - Export Controlled - ECCN: EAR99 42