EEN-E1010 Power Plants and Processes Course

Transcription

1 Course Understanding Power Production Students Laboratory Manual Steam Turbine Electrical Generation Course Instructors: Assoc. Prof. Mika Järvinen, M.Sc. Mohamed Magdeldin, M.Sc. Thomas Kohl Edition Author Date V.01 Mohamed Magdeldin

2 Contents 1: INTRODUCTION Rankine Cycle The Laboratory Setup Burner Boiler Sight glass Boiler pressure gauge Steam admission valve Steam turbine Generator Condenser tower Data acquisition system Operator panel Liquid propane cylinder Flue gas temperature thermocouple General Operational limitations BOILER BURNER GENERATOR General Guidelines : Pre-operation Preparation : System Operation Prestart check Start operation Steady state operation (Experimental run)

3 3.4 Shutdown : Practical Guidelines for Reporting Technical Report Guidelines Oral presentation RankineCycler Data Run Plots System Analysis Boiler Turbine Condenser Overall System

4 List of Figures Figure 1. Schematic of an ideal Rankine cycle Figure 2. PV and TS property diagram for the ideal Rankine cycle Figure 3. Temperature- Entropy diagram representation of the four processes within the Rankine cycle... 6 Figure 4. Image of the RankineCycler TM laboratory setup Figure 5. Boiler assembly Figure 6. Steam admission valve Figure 7. CAD cutaway of the steam turbine Figure 8. Steam turbine Figure 9. Electrical generator Figure 10. Cooling tower Figure 11. Screenshot of the data acquisition system of the RankineCycler Figure 12. Flue gas temperature measurement Figure 13. Schematic of the boiler tubing Figure 14. Caster wheels closed position Figure 15. Snapshot of Load switch and rheostat position during the prestart checkup Figure 16. Snapshot of cooling tower draining step Figure 17. Snapshot of boiler front door during prestart check Figure 18. Snapshot of boiler drain check during prestart check Figure 19. Snapshot of proposed beaker position for boiler fill during prestart check Figure 20. Snapshot of the location for the aluminum coupler attachment to the boiler Figure 21. Location for observation of burner operation Figure 22. Steam admission valve rotation counter-clockwise and clockwise to preheat the system Figure 23. Snapshot of the target operating conditions for the generator after preheating is completed Figure 24. Snapshot of turning off the BURNER SWITCH during Shutdown Figure 25.Snapshot of turning off the OPERATOR PANEL GAS VALVE during Shutdown Figure 26. Snapshot of turning off the LOAD RHEOSTAT during Shutdown Figure 27. Snapshot of turning off the LOAD SWITCH during Shutdown Figure 28. Snapshot of turning off the MASTER SWITCH during Shutdown Figure 29. Snapshot of turning off the FUEL SOURCE during Shutdown

5 1: INTRODUCTION One of the most significant contributions to the development and growth of our modern technological way of life has been the ability to extract vast amounts of energy from available natural resources. These energy sources allowed us to generate and control work, power and heat to meet the functional demands of societies around the world. Typical natural resources that are currently in use for energy purposes include petroleum oil, natural gas, coal, biomass, water, wind, solar, and nuclear. The production of heat and power is derived from man-designed thermodynamic cycles that manipulate the existing conditions of a working fluid to extract naturally stored energy into a usable form. Several cycles have been developed through history, however the Rankine cycle remains to be the most dominant application in terms of market share (almost 90%), as it could be applied efficiently with a wide range of fuels. The cycle is named after the Scottish civil engineer William Rankine (pronounced Rang-Keene ), which is considered one of the founding fathers in the field of thermodynamics. In a power cycle, chemical energy of the fuel is transformed (through an intermediate step of heat generation) into mechanical work. In a Rankine based power plant, the working fluid, which is water, undergoes phase transformation into steam at elevated thermodynamic conditions and is used to drive a turbine, where mechanical energy is finally transformed into the desirable or target product of electricity. The real Rankine cycle found in existing power plants is much more complex and includes variations from the idealized cycle, however the conceptual thermodynamic steps remain the same. Upon completion of this laboratory assignment, as part of the course EEN-E1010 Power Plants and Process at Aalto University School of Engineering, a solid and fundamental understanding of the core driving units in commercial power production is obtained. The RankineCycler setup will offer an opportunity for a hands-on experience on the operation and control of a lab-scale steam power plant. The cycle sub-processes are measured during operation and analyzed to better understand their performance characteristics. This knowledge will hopefully transfer very well into full-scale systems within the power production industry. Disclaimer: Some of the content in this laboratory students manual is based on the instruction and operation manual documents provided by Turbine Technologies LTD for educational purposes of operating the RankineCycler TM steam turbine power system, model: RC

6 1.1 Rankine Cycle 2 q in 3 Boiler Turbine W p Pump W t Condenser 1 4 q out Figure 1. Schematic of an ideal Rankine cycle. Q stands for heat and W for work. (Blue lines represent water in liquid state, Red lines represent water in elevated steam conditions, Black lines are energy streams) The ideal Rankine cycle consists of four subsequent processes for the working fluid, water to go undergo for the production of electricity, as shown and numbered in Figure 1. The theoretical starting point of the cycle, state 1 is the water in its liquid form near ambient conditions. The first process is the isentropic compression (1-2) of the working fluid by the mechanical work from the pump to elevated pressures. The introduction of heat is the following step in an isobaric manner (2-3), for e.g. in a boiler, where liquid water undergoes phase change into saturated and then finally superheated steam at state 3. Then the work production step takes place, where the pressurized steam is expanded isentropically (3-4) within the turbine to extract mechanical work. Finally, to close the cycle, remaining heat is removed in an isobaric manner within the condenser (4-1) for the working fluid to return to the initial state of saturated liquid. The thermodynamic cycle is further shown on the property diagrams in Figure 2, where the phase change or cross from liquid to vapor and vice versa along with intermediate two-phase state are illustrated. Figure 2. PV and TS property diagram for the ideal Rankine cycle. 5

7 The four main steps of the real Rankine cycle are further demonstrated in Figure 3; where (1-2) is liquid compression, (2-3) is the isobaric heat addition, (3-4) steam expansion and finally (4-1) water condensation. In practice, the ideal cycle is not achievable and a deviation is present due to irreversibility in the mechanical operation of the components, such as friction or heat transfer losses. The clear variation of the real cycle (shown in Figure 3) to the ideal cycle (shown in Figure 2) is the presence of the irreversible steam expansion step (3-4). As the introduction of the superheated steam through the nozzles of the turbine and the process of vapor hitting the turbine blades and moving the shaft is irrecoverable in nature. As such, step (3-4) is not isentropic and entropy is generated in that step which leads to less work extracted and then additional heat is needed to be removed within the condenser step. Figure 3. Temperature- Entropy TS diagram representation of the four processes within the Rankine cycle. Note: this is not an ideal cycle. As such, the energy analysis for the four processes/components could be defined as, Water pump (1-2): W p = h 2 h 1 Boiler (2-3): Q in = h 3 h 2 Turbine/Expander (3-4): W p = h 3 h 4 Condenser (4-1): Q out = h 4 h 1 In addition, the overall thermal efficiency of the cycle is a combination of all four equations. Where, the cycle input is the amount of heat added and product would be the net generated work. Rankine cycle efficiency, η T = W net Q in 100% = (h 3 h 4 ) (h 2 h 1 ) h 3 h 2 100% 6

8 1.2 The Laboratory Setup Figure 4. Image of the RankineCycler TM laboratory setup. The RankineCycler setup, shown in Figure 4, is a lab scale power generation system specifically designed for educational purposes. The setup resembles the operation and control of an industrial scale steam cycle for the production of electricity, where each component models the full size components in purpose and function. In this section, the RankineCycler components will be thoroughly introduced, including all components that make up the actual system, its integrated data acquisition system and virtual instrument panel. From there, operating the system allows the study of the important performance parameters such as; fuel energy density, boiler heat flow, energy conversion efficiency, system mass flow rate, turbine work rate, generator output/efficiency, condenser efficiency, total system efficiency Burner A forced air gas burner provides the necessary energy to vaporize the liquid working fluid as it passes through the boiler, illustrated in Figure 5. An electrically driven centrifugal blower provides combustion air to the burner through a blower duct. A fuel line is routed through this duct, delivering fuel to a gas 7

9 mixing nozzle. The fuel and air are further mixed by a vortex disk that introduces turbulence to the flow. A hot surface" igniter located in the fixed rear boiler door and at the end of the primary flame tube provides the ignition source. The igniter is a resistance element that glows when current is applied to it. The fuel and air mixture combusts when it comes in contact with this glowing element producing a flame confined within the primary flame tube. Once combustion commences, the flame is self-sustaining and the igniter will shut off Boiler The boiler facilitates the vaporization of the system working fluid, making it available to the turbine for power extraction. All boilers provide for some manner of heat transfer between the heat source and the system working fluid. The RankineCycler utilizes a fire tube or shell type boiler arrangement which is representative of over 80% of all boiler systems in use today. The shell of the boiler is an 8 in (20.3 cm) diameter by 11.5 in (29.2 cm) long stainless steel cylinder. The cylinder holds both the working fluid of the system as well as the high-pressure vapor prior to it exiting to the turbine. To allow heat transfer, 17 tubes of 0.5 in diameter (1.3 cm) pass through the cylinder allowing hot combustion gasses from the burner to flow through" the boiler. Five of these boiler tubes lie above the full water line. A primary flame tube 2 in (5.1 cm) in diameter also passes through the boiler and holds the flame produced by the burner. The walls of the 17 tubes and the primary flame tube provide nearly 380 in2 (2,451.6 cm2) of surface area for heat transfer. Positive pressure provided by both the blower and the expansion of the combustion gasses moves the hot air through and out of the primary flame tube. The rear boiler door then ducts this air to the 17 through tubes. The combined volume of the 17 through tubes is just under that of the primary flame tube, insuring an even air flow with maximum surface area contact. The hot air exits the through tubes and is ducted by the front boiler door through a vertical stack, exhausting the combustion gasses up and away from the boiler. The front boiler door is hinged while the rear is fixed. A latch secures the front door in the closed position while the system is operating. When the system is not operating and sufficiently cool, the front door may be unlatched and opened for viewing. The general arrangement of the through tubes and the primary flame tube can be seen. The rear door holds the hot surface gas igniter while the front door holds the blower unit and the exhaust stack Sight glass The sight glass provides an indication of the relative level of working fluid within the boiler. An upper and lower adjustable bezel allow the extents of working fluid to be marked. These markings make it easy to measure the amount of working fluid consumed during operation of the system. Attached to the bottom of the sight glass is the fill fitting, connecting the sight glass to the boiler and permitting the boiler working fluid level to show in the sight glass. At the top of the sight glass is a vent fitting that also connects back to the boiler to equalize pressure. The sight glass is not calibrated and only provides an indication of the boiler fluid level. Because of the curvature of the boiler cylinder and the presence of the through tubes, the level in the sight glass is non-linear over the volume of the boiler. 8

10 Boiler pressure gauge Figure 5. Boiler assembly: 1- burner, 2- boiler 3- sight glass and 4- boiler pressure gauge. An analog pressure gauge is installed providing a direct read out of available boiler pressure. The gauge indicates the normal range of operation with a white background. The red area of the gauge indicates pressure conditions that exceed normal operating limitations Steam admission valve The steam admission valve is a needle type valve that regulates steam vapor flow to the turbine. In fully clockwise position, it is CLOSED, preventing flow. In fully counter-clockwise position, the valve is OPEN and the full flow of steam is available to the turbine. Intermediary positions regulate accordingly. In addition to the steam admission valve setting, steam flow is dependent on boiler pressure and temperature. Figure 6. Steam admission valve. 9

11 1.2.6 Steam turbine The steam turbine provides useful work through the extraction of energy from the vaporized working fluid provided by the boiler. High pressure steam is directed through a nozzle, forcing the steam to impinge directly on the blades of the turbine wheel causing it to rotate. This rotation is then used to derive useful work. The single stage turbine unit is made up of a front and rear housing, each precision machined and fitted with a carbon bearing requiring no additional oil or lubrication. 2 3 Figure 7. CAD cutaway of the steam turbine. The three main functional steps within the turbine are shown in Figure 7 and could be summarized as: 1. Steam enters inlet port at the bottom left. 2. Steam flow forced through slits in stator ring (purple), impinging on turbine blades, spinning turbine wheel (red). 3. Steam exits turbine to condenser. 1 In addition to the inlet and outlet fittings in the front and rear housing, respectively, two other fittings provide transducer access to turbine inlet temperature and pressure as well as turbine outlet temperature and pressure. These values are measured by the data acquisition system and available on the computer. Figure 8. Steam turbine. 10

12 1.2.7 Generator The generator utilizes the rotational motion of the turbine to produce electrical energy. A four-pole, permanent magnet, brushless design, the generator is directly coupled to the output shaft of the turbine and supported on its own set of preloaded ball bearings. Both alternating current (AC) and direct current (DC) are available at the generator outputs Cooling tower Figure 9. Electrical generator. The cooling tower facilitates heat transfer between the hot vapor exiting the turbine and the relatively cool ambient air surrounding the tower. The tower mantle, manufactured from aluminum, provides the heat transfer interface and a condensation surface. Steam enters the cooling tower through a distribution manifold that disperses the steam within the tower to maximize contact with the mantle. Four internal stainless steel baffles further direct the steam along the mantle, while allowing condensate to run back to a catchment basin at the bottom of the tower. This basin can be drained, using the attached hose and pinchclamp, to accurately measure the amount of condensate collected Data acquisition system Figure 10. Cooling tower. The Rankine Cycler is equipped with a National Instruments 6218 precision data acquisition system which provides full range of system parameter measurement. This system, consists of a suite of sensors, excitation power sources, signal conditioners, data acquisition hardware and user interface software, when used in conjunction with an appropriate computer, allows actual run-time data to be displayed and recorded for later analysis. 11

13 Operator panel Figure 11. Screenshot of the data acquisition system of the RankineCycler. The panel consists of the following control switches: Keyed Master Switch: The key lockable system master switch controls the supply of electrical power to the main bus that powers the indicator lights, boiler combustion boiler and the gas control module. GREEN indicator light will illuminate when this switch is selected ON and power is available. Burner Switch: The burner switch enables the gas control module and powers the burner blower. A RED indicator light above the switch will illuminate when this switch is selected ON and power is available to the burner circuits. Low Water Indicator Light: RED indicator that shows a warning by the low water level in boiler. Load Switch: The load switch enables the load bank. The load bank presents a true load to the generator, allowing the operator to simulate conditions at a full scale power station when consumer demand fluctuates. Load Rheostat Control: The full counter-clockwise position of the control represents NO LOAD, full clockwise position of the control represents FULL LOAD. Operator Panel Gas Valve: Rotating the black gas valve knob counter-clockwise to the 3 o'clock position OPENS the valve. Rotating the valve knob clockwise to the 6 o'clock position CLOSES the valve and prevents any flow of gas through the regulator. Amp Meter: The amp meter indicates the amount of current the load is drawing based upon the load (as set by the Load Rheostat Control) and the available voltage (as provided by the generator; a function of generator speed/rpm). Volt Meter: The volt meter indicates the amount of voltage the generator is providing (a function of generator speed/rpm). 12

14 Liquid propane cylinder The cylinder contains the fuel necessary to operate the system. The fuel regulator is completely closed during startup and then completely open when operation takes place. The Operator Panel Gas Valve in the operator panel controls the flow of fuel to the burner, and is set to a constant value throughout the experiments Flue gas temperature thermocouple The temperature thermocouple is inserted into the flue gas exhaust to record the outlet temperature. A measurement device will be provided during the experiment to take sample readings, shown in Figure General Operational limitations Figure 12. Flue gas temperature measurement. The RankineCycler is designed to be operated within the following limitations. Under no circumstances should these limitations be exceeded by any margin. Operator safety and efficient operation of the RankineCycler is contingent upon these limitations being followed BOILER MAXIMUM OPERATIONAL BOILER PRESSURE psi (827 kpa) MAXIMUM OPERATIONAL BOILER STEAM TEMPERATURE ±F (320 ±C) MAXIMUM OPERATIONAL BOILER VOLUME oz (6,000 ml) OPERATING FLUID WATER BURNER FUEL LIQUID PROPANE (LP) ONLY GENERATOR MAXIMUM GENERATOR OUTPUT, Voltage Volts MAXIMUM GENERATOR OUTPUT, Current Amps MAXIMUM GENERATOR OUTPUT, Power Watts MAXIMUM GENERATOR SPEED, RPM RPM ABNORMAL SHUTDOWN OFF-OPEN-OFF The RankineCycler is designed with the necessary safety alarms and switch offs that minimize hazardous operation and ensures operator safety. In the unlikeliness of abnormal events or accidents (Fire or electrical malfunction) taking place during the operation, familiarize with the following ABNORMAL 13

15 SHUTDOWN procedure. CAUTION that this procedure is for the worst case scenario and will be performed by the TEACHING ASSISTANT. The OFF-OPEN-OFF procedure includes 1. OFF Shut OFF the MASTER SWITCH, to cut off all electrical system operation. 2. OPEN Fully OPEN the STEAM ADMISSION VALVE, to relieve system pressure. 3. OFF Shut OFF the supply of gas to the burner. 1.4 General Guidelines The following General Guidelines are offered as reminders of items requiring particular attention, further details on each are mentioned throughout the manual. Mandate the appropriate personal safety equipment for all operators and observers. Know the facility safety policies, emergency contact numbers and location of fire extinguishers. Read and become familiar with the RankineCycler Student's Manual. DO NOT operate RankineCycler without first becoming familiar with the Student's Manual. DO NOT operate the system unattended. Use the provided checklists during every operation. Lock all four caster wheels during operation. Use only in a well ventilated area. Continually monitor all system parameters and be attentive for out of limit readings. Immediately consult with the teaching assistant if anything is questionable. DO NOT exceed scale readings/limitations on any instrument or gauge. Remember, the working fluid is high temperature, pressurized steam. Consider all surfaces to be HOT during and for a significant time after operation. DO NOT touch any surface during operation. DO NOT move the system while operating or when the boiler is pressurized. DO NOT allow the boiler water level to become less than 1.0 in (2.5 cm) as indicated on the sight glass. DO NOT attempt to fill the boiler while the system is pressurized. DO NOT open the boiler doors while hot, doing so may cause permanent warp-age of the boiler cradle. DO NOT tighten or adjust fittings while system is under pressure. DO NOT tap on or scratch boiler sight glass. 14

16 2: Pre-operation Preparation In preparation for the system operation and data analysis, students are advised to read through the complete laboratory manual, familiarize themselves with the setup and perform some background reading on the Rankine cycle as well as the different operational components. EACH STUDENT IS EXPECTED TO PRESENT A PERSONAL DATA SHEET ANSWERING THE FOLLOWING QUESTIONS BEFORE TAKING PART IN THE EXPERIMENT! POINTS WILL BE DEDUCTED FROM THE FINAL REPORT GRADE OF THE GROUP FOR MISSING DATASHEETS. 1- Liquid propane (LP) is the current used fuel, where it is vaporized and introduced into the burner. What is the energy content per unit volume and mass of gaseous LP? Identify both the lower and higher heating value of LP? If we assume a flow of 6 L/min at steady state, what is the energy consumption per hour of the system? What are the expected products in the flue gas, (assume 100% content of C3H8) in the cases of excess, stoichiometric and deficit oxygen supplied? 2- Sketch a process flow diagram (use blocks to show components, don t need to draw each component) of the laboratory setup, and illustrate the major input and output material and energy streams. (Hint: Microsoft Visio is a good tool to assist you. However, hand sketched diagrams are perfectly accepted). 3- The boiler is shell and tube style construction. Calculate the available volume for water in the boiler given the basic construction dimensions shown in Table 1. If the boiler is filled with 5500 ml of water, what is the fill percentage and estimate the number of flame tubes that would not be submerged within the working fluid. Table 1. Boiler basic dimensions. Main Shell External Length cm Main Shell Wall Thickness cm End Plate Outside Diameter cm End Plate wall thickness cm Main Flame Tube Outside Diameter 5.08 cm 16 Return Pass Flame Tubes Outside Diameter 1.9 cm Figure 13. Schematic of the boiler tubing. 4. What are the operating limitations for the BOILER pressure, generator voltage and ampere output. 5. State the three main steps in the ABNORMAL SHUTDOWN procedure. 15

17 3: System Operation This section includes the standard procedural steps for Prestart check, Startup operation, Steady state operation and Shutdown, which allows for an efficient and safe operation of the system. Familiarity with these procedures must be made prior to operating the RankineCycler for the first time. Even experienced operators should continue to use the checklist for each operational run to eliminate the possibility of overlooking or inadvertently eliminating a necessary step. All steps are expected to be conducted by the student group members, under the supervision of the teaching assistant, and should be followed exactly in the same sequence presented here in the manual. The data acquisition system is used to capture all operational values from startup to shutdown, however some data are required to be obtained manually: Steady state start time. Steady state stop time. Initial, intermediate and final Boiler fill estimate on the sight glass. Amount of condensate collected during experiment. Flue gas temperature readings. 3.1 Prestart check The PRE-START checklist must be completed prior to operating the RankineCycler. The checklist ensures that all system components are ready for operation and that heat can be safely applied to the boiler. 1. THE AREA CHECK and SAFETY MEASURES- assessment to VERIFY SUITABILITY OF THE OPERATION and the SAFETY of the operators (Each group member should present a personal data sheet similar to that shown in Section 2). This step is to ensure all members of the group are familiar with laboratory safety procedures, any additional equipment requirements and an opportunity for consultation with the teaching assistant on any questions or concerns before operation. All operators and personnel in the immediate area should know the location of fire extinguisher equipment, circuit breakers and fuel supply valves, as well as being familiar with existing safety policies and procedures, emergency escape routes, and emergency services telephone numbers/points of contact. 2. CASTER WHEELS must be in the LOCKED position prior to operation, preventing movement that may either pose a safety hazard or disrupt critical operations such as boiler filling. Figure 14. Caster wheels closed position. 16

18 3. Ensure the following switch positions: a. MASTER SWITCH - OFF position: GREEN light OFF b. BURNER SWITCH - OFF position: DOWN position c. LOAD SWITCH - OFF position d. LOAD RHEOSTAT Minimum load FULL COUNTER-CLOCKWISE POSITION Figure 15. Snapshot of Load switch and rheostat position during the prestart checkup. e. OPERATOR PANEL GAS VALVE OFF positon 4. Perform a thorough VISUAL INSPECTION of each major component and the system. Verify that no components were damaged, tampered with or removed since the last run. 5. Drain the COOLING TOWER using the attached clear tubing and pinch-clamp. Discard any condensate collected, and empty in drain after measurement, DO NOT RE-USE. Figure 16. Snapshot of cooling tower draining step. 6. The FRONT BOILER DOOR must be CLOSED and LATCHED (REAR DOOR is stationary). Figure 17. Snapshot of boiler front door during prestart check. 17

19 7. The STEAM ADMISSION VALVE must be OPEN to allow air to vent out of the boiler during the fill operation. Water will not enter the boiler with the valve closed. 8. The BOILER should be DRAINED completely using the fill/drain valve and beaker assembly. Figure 18. Snapshot of boiler drain check during prestart check. 9. Fill the BOILER with 5,500 ml of clean, distilled water for the most efficient operation. Any quantity over this recommended amount will likely degrade boiler performance and may prevent the boiler from producing any pressure. During fill, scale the boiler level on the sight glass, in order to be able to estimate the water consumption during steady state. With the beaker ball valve closed, fill the beaker to the desired boiler level. a. Place the beaker on a firm support higher than the boiler fill/drain valve at the rear of the boiler. If this is the first run of the day or adequate time has passed that the cooling tower is sufficiently cold, beaker can be placed on the tower. Figure 19. Snapshot of proposed beaker position for boiler fill during prestart check. b. Insert the aluminum coupler at the end of the beaker hose assembly into the fill/drain valve coupling hole. 18

20 Figure 20. Snapshot of the location for the aluminum coupler attachment to the boiler. c. Open the beaker ball valve to allow water to fill the boiler. At the meantime SCALE (calibrate) the SIGHT GLASS at equal intervals. (recommended every 500 ml) d. When all the water has emptied from the beaker, close the beaker ball valve and remove the aluminum coupler from the fill/drain valve. If the beaker assembly was placed into the top opening of the cooling tower while filling the boiler, remove it before proceeding to the next step. 10. Now, put the STEAM ADMISSION VALVE back to the CLOSED position which was opened before filling the boiler. Starting with a closed valve lets boiler pressure properly build up. 11. Now, connect the COMPUTER DAQ SYSTEM USB cable to the USB system on the left side panel of the RankineCycler. Make sure the computer is OFF prior to connecting the cable or the DAQ Module hardware/software may not properly initialize. 12. Connect the RANKINECYCLER ELECTRICAL SERVICE to the electrical outlet. 13. Check the FUEL SOURCE line connection to the LP FUEL SUPPLY TANK. 3.2 Start operation The Start operation procedure is necessary to take the RankineCycler from cold shutdown conditions through preheating and to run-time data collection at steady state. 1. THE COMPUTER DAQ SYSTEM should be turned on. Note: ensure that the computer USB connection is attached to RankinCycler before the computer is turned on, to avoid improper DAQ module hardware/software initialization. TURN DATA LOG ON. 2. FUEL SOURCE regulator is opened, and initial FUEL LEAK CHECK must be completed before any further steps take place. Note: look out for either a hissing sound or an odor. 3. OPERATOR PANEL GAS VALVE is turned to ON position. 4. MASTER SWITCH key is turned to ON position. GREEN light is illuminated, which indicates that electrical power is now available to the system components. 5. Check if the FLUE GAS TEMPERATURE MEASUREMENT and GAS ANALYZER devices are working. 6. Select the BURNER SWITCH to the ON position. RED light is illuminated. Observe the COMBUSTION BLOWER and verify if it is on. The blower motor should be heard as it begins to rotate, drawing air into the burner and forcing it through the boiler. 19

21 NOTE: To PURGE FUEL LINES, you could allow the blower to operate for 45 seconds then turn the BURNER SWITCH off and immediately back on (CONSULT WITH THE TEACHING ASSISTING BEFORE PURGING). 7. VERIFY that the BURNER has LIT within 45 SECONDS of selecting the BURNER switch on. It should be noted that the burner may occasionally burp" - producing an audible popping noise with a small blue flame present at the blower inlet. This behavior is normal and should NOT be considered a fire requiring the execution of the fire abnormal procedures. Figure 21. Location for observation of burner operation, Blue flame is considered the first sign, in addition to a distinguishable gas burning noise. 8. Monitor BOILER PRESSURE on the pressure gauge as well as through the DAQ system. VERIFY POSITIVE PRESSURE within 3 MINUTES from start. If not, turn off the BURNER SWITCH and investigate. Verify that the proper amount of water is in the boiler and the STEAM ADMISSION VALVE is fully CLOSED. 9. Allow the indicated BOILER PRESSURE to rise to approximately 120 psi (827 kpa). 10. The system should now be PREHEATED. This allows the steam lines, valves and turbine to come up to the proper operating temperature. The turbine bearings are also lubricated at this time. During the preheating period, small vapor leaks and condensation droplets may be seen around the turbine and related fittings. This is normal and should subside once the turbine bearing clearances close due to thermal expansion. The preheating process outlined below should take approximately 7 to 10 MINUTES to complete. This preheating process is essential to supplying the highest quality steam available to the turbine. If preheating is omitted, condensation will form in the steam lines degrading system performance overall. a. The STEAM ADMISSION VALVE should be turned counter-clockwise to OPEN. This will allow steam to flow throughout the system. The turbine/generator may or may not rotate at this point. b. Monitor BOILER PRESSURE until it falls to approximately 50 psi (345 kpa). During which the load switch (Turn ON) and rheostat knob will have to be used so the turbine/generator does not over speed (RPM should be below 2500) and not exceed 9 volts. (GROUP WORK IS ESSENTIAL AT THIS POINT TO SYNCHRONIZE THE RHEOSTAT ADJUSTMENT WITH THE RESULTING GENERATOR READING ON THE DAQ SYSTEM) 20

22 c. The STEAM ADMISSION VALVE should be turned clockwise to CLOSE. This will stop the steam flow and allow for boiler pressure to build up again. Figure 22. Steam admission valve rotation counter-clockwise and clockwise to preheat the system. d. Turn the RHEOSTAT knob back to original position and shut the LOAD SWITCH off. e. Allow BOILER PRESSURE to rise back to approximately 120 psi (827 kpa). 11. Open the STEAM ADMISSION VALVE slowly, while maintaining approximately 120 psi (827 kpa) of BOILER PRESSURE. Once the turbine begins to rotate, the generator will produce electricity. Monitor the turbine RPM, it should not exceed the safe limit of Generator output will be directly indicated on the VOLT METER. 12. Turn ON the LOAD SWITCH again. Continue opening the STEAM ADMISSION VALVE and simultaneously ADJUST the LOAD RHEOSTAT. Figure 23. Snapshot of the target operating conditions for the generator after preheating is completed. 13. In preparation of an experimental data run, the STEAM ADMISSION VALVE and the LOAD RHEOSTAT may continue to be adjusted to achieve a STEADY STATE CONDITION. Satisfactory run-time results can be achieved with the following values: a. An AMP METER indication of approximately Amps. b. A VOLT METER indication of approximately Volts. c. A BOILER PRESSURE indication according to experimental conditions (generally 120 psi (827 kpa)). 21

23 3.3 Steady state operation (Experimental run) This section illustrates the experimental procedure for operation, as well as the necessary data acquisition after steady state conditions are achieved. The system will be operated at 3 different pressure level conditions (around 120 psi 100 psi 75 psi), data will be collected for each and a system level analysis should be conducted for each. 1. To begin the experimental run, TIME and BOILER FILL LEVEL from the sight glass should be noted. This is essential as data log in the DAQ is not in real time (only cumulative time) so a comparison between the real time at which the log started and the experimental start is needed to establish the time interval for usable data in the steady state analysis. 2. CHECK with the teaching assistant that the data log for the flue gas analyzer is also turned on. 3. SET the SIGHT GLASS UPPER BEZEL to the current, indicated WATER LEVEL. This value will be compared to the end of the experiment level to validate your calculation for steam flow rate through the system. 4. Continue to use the STEAM ADMISSION VALVE to make PERIODIC ADJUSTMENTS maintaining the STEADY STATE established in the experiment (120 psi) for a total period of 4 MINUTES. 5. The FLUE GAS TEMPERATURE reading should be periodically taken and noted every 30 seconds for the duration of the 4 minutes. 6. At the END of the 4 minute interval, NOTE the time for the 120 psi run and NOTE down the new level of water in the BOILER from the CALIBRATED SIGHT GLASS, this data will be used to assume the steam flow exiting the steam admission valve during the run. 7. After completion of data collection for the first run, use the STEAM ADMISSION VALVE to make PERIODIC ADJUSTMENTS to bring the BOILER PRESSURE down to ( psi) and maintain set pressure range for a total period of 3 MINUTES. The RHEOSTAT KNOB should be adjusted accordingly to maintain the recommended operation conditions for the generator similar to the steady state. 8. Note the TIME of start and BOILER FILL LEVEL. Then REPEAT STEPS 4 to 6 for the new pressure level. 9. After completion of data collection for the second run, use the STEAM ADMISSION VALVE to make PERIODIC ADJUSTMENTS to bring the BOILER PRESSURE down to (70-80 psi) for a total period of 3 MINUTES. The RHEOSTAT KNOB should be adjusted accordingly to maintain the recommended operation conditions for the generator similar to the steady state. 10. Note the TIME of start and BOILER FILL LEVEL. Then REPEAT STEPS 4 to 6 for the new pressure level. 11. After finishing the three runs, the COOLING TOWER should be drained, to measure the amount of CONDENSATE collected during the experiment. As the condensate will contain suspended turbine oil, it is suggested that a disposable or condensate specific vessel be used. NOTE that the CONDENSATE is HOT, so should be collected with care. IMPORTANT NOTE: For the second and third run, make sure that the boiler water level doesn t drop too low. If you observe that this is the case, consult with the teaching assistant immediately. 22

24 A NUMBER OF RESPONSABILITIES COULD BE DELGETAED AMONG THE GROUP MEMBERS DURING THE THREE RUNS AND IT IS ADVISED TO BE SET AS PART OF THE PREPARATION BEFORE STARTING THE EXPERIMENT: 3.4 Shutdown a. A member of the group should be responsible for the check list and ensure the procedural sequence of the experimental run. b. A member of the group should monitor recommended operation conditions on the DAQ and liaison with other member handling the rheostat knob. c. A member of the group should handle the steam admission valve and the rheostat knob (generator load) along with monitoring the voltage and ampere readings of the generator from the panel. d. Water level measurement in the boiler. e. Data logging and time keeping for the three runs. f. Flue gas measurement (temperature) recording, the analyzer data will be provided by the teaching assistant. g. Condensate collection and data recording. The SHUTDOWN checklist ceases RankineCycler operation and places the system into a known, safe condition. 1. Turn the STEAM ADMISSION VALVE to the CLOSED position. 2. SET the SIGHT GLASS LOWER BEZEL to the current, indicated WATER LEVEL. This allows measurement of the boiler water consumed during the whole experimental run. 3. Select the BURNER SWITCH to OFF. Verify that the RED light is extinguished indicating that no electrical power is available at the burner or the blower. The blower should immediately stop rotating. Figure 24. Snapshot of turning off the BURNER SWITCH during Shutdown. 4. The OPERATOR PANEL GAS VALVE should be selected OFF. 23

25 Figure 25.Snapshot of turning off the OPERATOR PANEL GAS VALVE during Shutdown. 5. The LOAD RHEOSTAT should be turned FULL COUNTER-CLOCKWISE, resulting in MINIMAL LOAD. Figure 26. Snapshot of turning off the LOAD RHEOSTAT during Shutdown. 6. The LOAD SWITCH should be selected OFF. Figure 27. Snapshot of turning off the LOAD SWITCH during Shutdown. 24

26 7. The MASTER SWITCH should be selected OFF. Verify that the GREEN light is extinguished. Figure 28. Snapshot of turning off the MASTER SWITCH during Shutdown. 8. The STEAM ADMISSION VALVE should be turned to the fully OPEN position SLOWLY as to not exceed 9 volts. This relieves all remaining boiler pressure. 9. The FUEL SOURCE valve should now be turned OFF. Figure 29. Snapshot of turning off the FUEL SOURCE during Shutdown. 25

27 4: Practical Guidelines for Reporting This section shows the guidelines for the final technical report and presentation for each student group, as well as for laboratory run data acquisition and system analysis. 4.1 Technical Report Guidelines The technical report is expected to showcase the accumulated knowledge by the group members of the fundamentals of a Rankine cycle-steam power plant for design, operation and analysis purposes. Logically the language of the report should be in English only. All members of the group are expected to participate actively in the laboratory run as well as in reporting. Thus, the report is expected to include a sub-section as part of the introduction which specifies the delegated tasks and the contributions of each member. The expected outline of the report (chapters) includes: (Groups are free to restructure the report, this is merely a guideline for what should be included) Cover page. The cover page represents the title of the work, each group is free to choose the report name, which should reflect the topic of report as well as purpose of laboratory run or the main findings from the run. The page should include group number, list of members, and the schedule at which the laboratory session took place. Abstract. The abstract is a short summary of the report, maximum 200 pages, with emphasis on the highlights in the report. A list of 4 key words should be included at the end also. Table of content, list of Figures and list of Tables. Introduction. Clearly indicate the context/background of the technical report. The objective of the laboratory run. Group members contribution and designated tasks. Outline the reporting approach and content. Theoretical background. Use an appropriate title based on the content that is included. The chapter should include all the necessary theory and background knowledge for the following chapters. In addition to a literature review that lists all the sources for equations used in the calculations part. Laboratory Setup and Procedure Refer to the RankineCycler schematic and explain the overall operation. Point out and explain the similarities and differences between the laboratory setup and the industrial scale systems. Identify what are the processing parameters measured and why. Provide a brief description of the experimental procedure (Do not simply copy the Laboratory manual). List sets of experiments done and the range of parameters that have been tested. 26

28 Results. List down and organize the laboratory run data in a coherent structure that would support the following discussion. Select which data are relevant here and which could be rather included in the Appendices. Present the data in a meaningful way, that major findings could be extracted from them, thus graphs are always preferable to tables. (Note: tables are still recommended to use when listing data such as specifications) Discussion and Findings Describe how the results alter along the variation of certain process parameters and how such change would influence overall system and component performances. Identify sensitive (most impactful) parameters and validate through comparison with what is reported in literature. Note: This part should also include an analytical comparison between the steady state operation at 120 psi and part load operations at 100 and 75 psi. Conclusions. Brief summary of the main findings in the report. References. Nomenclature and Appendices if needed. In general, each report should have enough detail so that the reader can comprehensively follow and reproduce your main findings. The report is expected to list in detail the procedure and results of your laboratory run, in addition to the discussion and analysis of the system performance. The latter two will distinguish reports from each other and will significantly influence the final grading. The writing style is expected to be in a technical and direct manner. 4.2 Oral presentation The schedule for the presentation is announced during the course lectures. The presentation is a group effort where all members are expected to take part. The maximum duration of the presentation per group is 20 minutes, with an additional 5 minutes allocated for a Q&A session. The content of the presentation should be based around the technical report. However, complete freedom is given to the group in the presentation design or for addition of elements to the presentation technical content deemed by the group beneficial. The use of any support materials or tools during the presentation will be considered a bonus. The overall grading for the presentation will be based on organization, time management, technical content, presentation skills (language proficiency, demeanor & body language) and creativity. The peer review process will take place after the oral presentation at which names of the group members would be drawn anonymously, every member will be given two other member names to evaluate. The results would be collected by the teaching instructors (only individuals to have access to that information) and would be combined along the technical report and oral presentation grading for the overall assignment grade. 27

29 4.3 RankineCycler Data Run Plots Graphically plot the RankineCycler Run Data extracted from the DAQ system as a first step for the following system analysis and performance calculations to be conducted in the following sections. Plot the following operation parameters vs. TIME, utilizing MS-Excel, where the different operational states (start and preheat, three different pressure levels and transitional states) are clearly defined and distinguished: Fuel Flow. Boiler Temperature. Boiler Pressure. Turbine Inlet/Outlet Temperature. Turbine Inlet/Outlet pressure. Generator DC Amps output. Generator DC Voltage Output. Turbine RPM. Power produced. From the gas analyzer data, plot the flue gas concentration of Oxygen, Carbon dioxide and Carbon Monoxide vs. TIME, while showing the three steady state conditions. Note that the three steady state conditions will be the basis for your system level analysis. From the plots and the data collected from the system run, record the following for each steady state pressure condition: Average Fuel Flow. Average Boiler Temperature. Average Boiler Pressure. Average Turbine Inlet/Outlet Temperature. Average Turbine Inlet/Outlet pressure. Average Power produced. Water consumption from the Boiler. Condensate amount collected. 28

30 4.4 System Analysis The objective is to conduct performance calculations using controlled volume thermodynamic conservation laws to develop the mass and energy balance of the system and its components. Any thermal (steam) power plant performance is mainly characterized by Mechanical power output, W t (kw) Electrical power output, W el (kw) Cycle thermal efficiency, η th (%) Heat rate, HR (kj/kwh) Steam rate, m s (gm/s) Fuel rate, m f (gm/s) Electrical (overall) efficiency, η el (%) Capacity factor, reliability and operating flexibility. (not included in calculation but should be discussed in the report) In your calculations, refer to the lecture and exercise materials along with the reference book Advanced Energy Systems by Khartchenko for detailed formulation of the equations. Assume kinetic and potential energy as negligible throughout the calculation for the three pressure level cases. The data needed for these calculations come from the information plotted and recorded in the previous section. Note that steam tables should be also used to gather state data for each of the points of interest within the system. Note that although the accuracy of data is an important operational consideration for industrial application, in this laboratory assignment, the emphasis is on showing the ability to interpret the data collected from the laboratory run and utilize it for thermal analysis of the overall plant as well as the sub-processes Boiler Perform the mass and energy balance for the boiler from both the flue gas and water stream side, show an illustration of the material and energy streams on a diagram and specify the following: Heat flow into the Boiler. (kw) Determine the Air to Fuel ratio. Hint: use stoichiometric calculations. Heat losses with the Flue gas. (kw) Heat production from the Boiler in the product steam. (kw) Boiler thermal efficiency. (%) Turbine Calculate and specify the following: Isentropic efficiency of the turbine. (%) Generator efficiency. (%) Heat losses within the steam admission valve (losses due to throttling effect). (kw) 29

31 4.3.3 Cooling Tower Perform the mass balance only for the cooler tower, show an illustration of the water streams on a diagram and specify the following: Total heat rejected in the condenser. (kw) Tower extraction efficiency. (%) Hint: ( m condensate minlet ) The current cooler is air-cooled, calculate the theoretical amount of cooling medium needed if it was water cooled. (kg/s) Overall System Perform the overall steady state mass and energy balance, show an illustration of all material and energy streams (with computed values) on a process flow diagram, and specify the following: The cycle thermal efficiency. (%) The plant electrical efficiency. (%) Also show the T-S and H-S diagrams of the plant for the three steady state cases. 30