What to Expect from Your EtaPRO Investment

Transcription

1 What to Expect from Your EtaPRO Investment Benefits of Deployment Introduction Power plants seeking to improve their competitive position have recognized unit heat rate as an indicator of plant health leading to maintenance/improvement of overall plant efficiency, capacity, and reliability. This document describes the monitoring functions of the EtaPRO System for a coal fired power plant and lists typical problem areas where EtaPRO can be of benefit in identifying and quantifying the impact of plant degradation and operation on plant economy. The heat rate and financial impacts of these issues are quantified for generating units of various sizes. Tables of opportunity costs useful for justifying real-time monitoring systems are presented. Lastly, sample case studies and applications are described. Monitoring Functions The following are indicative of the types of problem areas that EtaPRO identifies, quantifies, and trends. Issues typically fall into one of three broad categories: 1) Operational Issues, 2) Maintenance Activities, and 3) Capital Improvement. Condenser Optimal Number of CW Pumps in Operations Condenser Air Ingress as Indicated by High Condenser Pressure/Condensate Subcooling Condenser Microfouling (biological, etc.) Low CW Flow Due to Waterbox Tubesheet Fouling (macrofouling) Low CW Flow Due to Low Waterbox Levels CW Pump Problems Air Ejector (vacuum pump) Problems High Heat Loading (FWHs out of service, etc.) Boiler Excessive/Insufficient Air Preheating for Cold End Protection/Air Heater Fouling High Exit Gas Temperature Due to Air Heater Fouling High Gas Inlet Temperature Low X-ratio Convection Pass Heat Exchange (e.g., economizer) Fouling Off-target AH X-Ratio Due to Boiler Casing Air Ingress (leading to derating during warm weather operation) FD Fan Imbalance Localized Air Heater Plugging Open Manway Fuel change High RH Spray Flows due to Secondary SH Fouling Waterwall Fouling 2008 GENERAL PHYSICS CORPORATION Page 1 of 10

2 Economizer Fouling Improper Burner Tilt Position High SH Spray Flows due to RH Fouling Cold Economizer Water Inlet or Outlet Temperatures Incorrect Temperature Indication (SH Outlet Header vs. Turbine Inlet) Cycle Isolation FW Heater Bypass Valves Leaking Through or Not Fully Closed NRV Not Fully Open Alternate/Emergency Drain Valve From Dearatpr to Condenser Open/Leaking Main Steam Dump Valve Leaking Steam Seal System Bypass Startup Valve Open Main Steam and Turbine Drain Valves Leaking Through or Not Closed Steam Turbine Control Valve Stroke Improper Adjustment/Operation (valves not fully open or valve disk separated from valve stme; reduced capacity) Failed Extraction Line Expansion Joint within Condenser (ineffective condensate heating; reliability: excessive steam load on upstream heater, excessive heat load to condenser) HP Turbine Cylinder Efficiency Copper Deposits in 2 nd Stage and beyond (condenser tube leak) Solid Particle Erosion (cycling units or units with numerous starts) Mechanical Damage Labyrinth Seal Wear/Damage Improper Control (Governor) Valve Stroke Pattern IP Turbine Cylinder Efficiency High N2 (IP Dummy, etc.) Packing Leakage Feedwater Heater High DCA (reliability issue: damage to tube bundle due to water flashing in drain cooler) Low Level Due to Controller Problem Low Level Due to Incorrect Level Indication Fouled Tubes High TTD Air binding/venting problem Fouled Tubes Pass partition plate leak-by/failure High Level Internal FW Bypassing External FW Bypassing Boiler Feed Pumps/Drive Turbines Increased Pump Speed Due to Worn Seals Pre-mature Roll-over to Main Steam Supply 2008 GENERAL PHYSICS CORPORATION Page 2 of 10

3 Excessive Recirculation Leading to Reduced FW Capacity Auxiliary Load Equipment Selection During Low Load Operation Financial Impact of Heat Rate Degradation Numerous opportunities exist for heat rate degradation in an operating power plant. This section highlights and quantifies the heat rate and financial impacts of typical problem areas. Heat rate impacts were accurately determined using a detailed plant heat balance model (GP s proprietary VirtualPlant ) to properly consider the interaction of boiler and turbine cycle components to determine the impact of degradation on the entire plant. This method is more representative of actual savings when compared to less sophisticated methods of considering the boiler and turbine independently. Table 1 below lists typical operating and maintenance issues that can adversely impact plant economy, along with sample deviations and their impact on net unit heat rate. As can be seen, the total heat rate opportunity cost is nearly 6% of the design heat rate. This is in line with GP s experience on 250+ MWe coal-fired generating units. Table 1. Impact of Degradation on Unit Heat Rate Heat Rate Heat Rate Problem Area Deviation % Btu/kWh (KJ/kWh) Throttle Pressure LOW -24 psi (-1.65 bar) (12) Throttle Temp LOW -10 F (-5.5 C) (4) Reheat Temp LOW -10 F (-5.5 C) (8) SH Spray HIGH 1% Throttle Flow (3) RH Spray HIGH 1% Throttle Flow (17) FW Temp to Boiler LOW -10 F (-5.5 C) (18) HP Heaters TTD HIGH +10 F (+5.5 C) (27) LP Heaters TTD HIGH +10 F (+5.5 C) (18) HP Heaters DCA HIGH +10 F (+5.5 C) (3) LP Heaters DCA HIGH +10 F (+5.5 C) (4) HP Drains to Condenser 100% (73) LP Drains to Condenser 100% (5) Condenser Pressure HIGH (High Load) 1 "Hga (0.034 bara) (18) Condenser Pressure HIGH (Low Load) 1 "Hga (0.034 bara) (87) Economizer Exit Gas Temp HIGH +10 F (+5.5 C) (5) AH Exit Gas Temp HIGH +10 F (+5.5 C) (35) AH Air Preheat Temp HIGH +10 F (+5.5 C) (10) Excess Oxygen HIGH +1% (23) HP Efficiency LOW -5% (123) IP Efficiency LOW -5% (88) Total Opportunity (563) Table 2 on the following page shows the financial impact of these parameters on three generating units of various ratings. A fuel cost of $3/MMBtu ( 1.50/GJ) and an annual capacity factor of 80% were assumed GENERAL PHYSICS CORPORATION Page 3 of 10

4 Table 2. Total Annual Opportunity Cost (200 MW, 400 MW, 600 MW) Problem Area Deviation 200 MW 400 MW 600 MW $ $ $ Throttle Pressure LOW -24 psi (-1.65 bar) 46,145 92, ,434 Throttle Temp LOW -10 F (-5.5 C) 10,487 20,975 31,462 Reheat Temp LOW -10 F (-5.5 C) 27,267 54,534 81,802 SH Spray HIGH 1% Throttle Flow 5,004 10,008 15,011 RH Spray HIGH 1% Throttle Flow 65, , ,166 FW Temp to Boiler LOW -10 F (-5.5 C) 71, , ,493 HP Heaters TTD HIGH +10 F (+5.5 C) 100, , ,530 LP Heaters TTD HIGH +10 F (+5.5 C) 67, , ,686 HP Heaters DCA HIGH +10 F (+5.5 C) 4,202 8,404 12,605 LP Heaters DCA HIGH +10 F (+5.5 C) 8,404 16,807 25,211 HP Drains to Condenser 100% 289, , ,356 LP Drains to Condenser 100% 16,780 33,560 50,339 Condenser Pressure HIGH (High Load) 1 "Hga (0.034 bara) 71, , ,943 Condenser Pressure HIGH (Low Load) 1 "Hga (0.034 bara) 341, ,951 1,025,927 Economizer Exit Gas Temp HIGH +10 F (+5.5 C) 16,234 32,469 48,703 AH Exit Gas Temp HIGH +10 F (+5.5 C) 136, , ,874 AH Air Preheat Temp HIGH +10 F (+5.5 C) 35,252 70, ,755 Excess Oxygen HIGH +1% 88, , ,282 HP Efficiency LOW -5% 485, ,328 1,455,492 IP Efficiency LOW -5% 347, ,806 1,042,210 Total 2,234,760 4,469,520 6,704,280 Assumptions: Fuel Cost = $3/MMBtu; Annual Capacity Factor = 80% Table 3 below shows the sensitivity of the Total Annual Opportunity Cost to fuel cost and the total MW capacity monitored. Tables 4 and 5 show the same information but in EUR and GBP currencies. Table 3. Total Annual Opportunity Cost (USD) MW Monitored $1 / MMBtu $2 / MMBtu $3 / MMBtu , ,920 1,117, ,920 1,489,840 2,234, ,117,380 2,234,760 3,352, ,489,840 2,979,680 4,469, ,862,300 3,724,600 5,586, ,234,760 4,469,520 6,704, ,607,220 5,214,440 7,821, ,979,680 5,959,360 8,939, ,352,140 6,704,280 10,056, ,724,600 7,449,200 11,173, ,097,060 8,194,121 12,291, ,469,520 8,939,041 13,408, ,841,980 9,683,961 14,525, ,214,440 10,428,881 15,643, ,586,900 11,173,801 16,760,701 Assumption: Annual Capacity Factor = 80% 2008 GENERAL PHYSICS CORPORATION Page 4 of 10

5 Table 4. Total Annual Opportunity Cost (EUR) MW Monitored 1 / GJ 2 / GJ 3 / GJ , , , , ,397 1,412, ,048 1,412,096 2,118, ,397 1,882,794 2,824, ,176,746 2,353,493 3,530, ,412,096 2,824,191 4,236, ,647,445 3,294,890 4,942, ,882,794 3,765,589 5,648, ,118,144 4,236,287 6,354, ,353,493 4,706,986 7,060, ,588,842 5,177,684 7,766, ,824,191 5,648,383 8,472, ,059,541 6,119,082 9,178, ,294,890 6,589,780 9,884, ,530,239 7,060,479 10,590,718 Assumption: Annual Capacity Factor = 80% Table 5. Total Annual Opportunity Cost (GBP) MW Monitored 0.50 / GJ 1.00 / GJ 1.50 / GJ , , , , ,048 1,059, ,536 1,059,072 1,588, ,048 1,412,096 2,118, ,560 1,765,120 2,647, ,059,072 2,118,144 3,177, ,235,584 2,471,168 3,706, ,412,096 2,824,191 4,236, ,588,608 3,177,215 4,765, ,765,120 3,530,239 5,295, ,941,632 3,883,263 5,824, ,118,144 4,236,287 6,354, ,294,656 4,589,311 6,883, ,471,168 4,942,335 7,413, ,647,680 5,295,359 7,943,039 Assumption: Annual Capacity Factor = 80% Case Studies & Applications The following case studies are indicative of the types of issues where EtaPRO has successfully been used to identify, quantify, and prioritize. Application - Large Mid-western U.S. Utility GP implemented a fleet-wide deployment of EtaPRO and VirtualPlant technologies for a large mid-western U.S. utility. These units range in side from 300 to 650 MW and predominantly fire Powder River Basis (PRB) coal. The issues and savings identified below are for the first 6 months of EtaPRO operation on 6 generating units GENERAL PHYSICS CORPORATION Page 5 of 10

6 Plant A - $1.56M Excessive Air Preheating $1,169k Feedwater Bypassing Top Feedwater Heater - $107k Steam Preheating Valve Leaking Through - $280k Plant B - $2.57M Excessive Air Preheating - $1,654k Low SH & RH Temperature Setpoint during Reduced Load Operation $180k Improper Turbine Control Valve Stroking Above 495 MW - $669k Condenser Pressure High Due to Throttling of Circulating Water Isolation Valve $70k High Auxiliary Condenser Backpressure - $45k Low X-ratio (Tramp Air Leakage) - $TBD Air Heater 1A Excessive Air Leakage - $TBD Plant C - $203K Excessive Air Preheating - $203k Low SH & RH Temperature Control Setpoints - $TBD Increased Condenser Backwash Frequency - $TBD LP FWH 1 Not Heating Condensate - $TBD Case Study - High Condenser Pressure In the case below, condenser cleanliness shows a steady decrease over a 6 month period, (Figure 1). Figure 2 shows the trend in condenser pressure with unit derating anticipated within the following 2 to 3 weeks. Annualized cost for operating with high condenser pressure calculated to be $650,000 for this 600 MW coal fired unit at approximately $2/MMBtu. Figure 1. Condenser Cleanliness Degradation 2008 GENERAL PHYSICS CORPORATION Page 6 of 10

7 Figure 2. Derating Predicted Within 2 to 3 Weeks POTENTIAL 5 Hga Case Study - Excessive Air Preheating The Average Cold End Temperature set point for air preheating was set too high, resulting in excessive air preheating. The mechanism of the loss is increased stack loss. Comparing Nov/Dec 2006 operations with same period one year later showed substantial reduction of loss with a net savings of $126,000. Figure 3. Derating Predicted Within 2 to 3 Weeks IMPROVED BACK- END CONTROL 2008 GENERAL PHYSICS CORPORATION Page 7 of 10

8 Case Study - Failed AH Sootblower In this example, the air heater parameters (exit gas temperature, x-ratio, gas-side efficiency) all showed a gradual divergence, indicating an imbalance in gas and/or air flows between the two air heaters. This resulted in an air heater internal inspection being scheduled for the following weekend. Figure 4. Diverging AH Exit Gas Temperatures The internal inspection showed that the sootblower piping had failed, resulting in plugging of the A heater. This is a common occurrence when steam traps malfunction resulting in a steam/water mix eroding the elbow as shown in the photo below. Figure 5. Failed Sootblower Steam Supply Piping 2008 GENERAL PHYSICS CORPORATION Page 8 of 10

9 Case Study Steam Turbine Deposits GP conducted a Thermal Audit of a 400 MW gas fired unit located in Egypt which was experiencing a capacity reduction. Trends in EtaPRO showed a gradual decline in MWe, throttle flow, and HP efficiency at valves-wide-open, along with a corresponding increase in first stage pressure, all consistent with deposits in the 2 nd turbine stage. Figure 6. Declining MW & Throttle Flow at VWO Sidi Krir Unit 3 Steam Turbine Trends ( ) 375 GEN WATTS Main Steam Flow from Boile Power Output and Steam Flow show gradual decline at approximately the same rate (slope). Both power and flow are down by 2% from Time Figure 7. Declining HP Efficiency & Increasing First Stage Pressure Sidi Krir Unit 3 Steam Turbine Trends ( ) HP Turbine Efficiency Actu First Stage Pressure HP Turbine Efficiency shows gradual decrease (-6%) since First Stage Pressure shows gradual increase, despite reduction in steam flow and power output. This pattern is consistent with steam path deposits Time 2008 GENERAL PHYSICS CORPORATION Page 9 of 10

10 GP s Monitoring & Diagnostic Center At GP's Monitoring & Diagnostic Center in Amherst, New York, our staff of plant experts uses EtaPRO to provide continuous monitoring and alerting of environmental, efficiency, and capacity problems for 35+ generating units under contract. Table 5 below lists the initial results for a 600 MW coal fired unit recently added to the complement of units being monitored by GP s M&D Center. This service is available on an annual contractual basis. Table 5. Initial Results 600 MW Coal Fired Unit Issue Number Title Description Annualized Cost Entered on 04/22/2008 at 10:20:22: 205 RMC: No. of CWPs Running Running with 3 CWPs instead of 4 as the CWP Advisor is recommending. This is resulting in a loss of 1.8 MW at a load of 632 MWg. $ 709,560 Entered on 04/23/2008 at 09:44:24: 207 RMC: AH A & B High EGT 208 RMC: IP Efficiency too High 210 RMC: AH A Low Gas In T & Low X-Ratio 211 RMC: High DA TTD 212 RMC: FWH F High DCA Source: GP Monitoring & Diagnostic Center At full load, both AHs are running 35 to 50 degf above target EGT, resulting in losses of $35/h to $65/h per AH. $ 350,400 Entered on 04/23/2008 at 11:12:55: Actual IP efficiency is consistently running 2-3% higher than expected. We need to switch to the new instrument(s) added during the upgrade which should lower the actual value considerably. Entered on 04/23/2008 at 11:55:12: Gas In T on A AH is 60 degf lower than B AH and X- ratio is low. Possible failure of expansion joint at economizer outlet? Entered on 04/23/2008 at 12:10:17: After outage ending 4/13/08, DA TTD is running about 6 degf higher than it was before the outage. Possible damage to DA on shutdown? Entered on 04/23/2008 at 12:46:05: FWH F DCA running 30 degf above expected at ~635 MWg since coming back from outage ending 4/13/08. Before outage it was 5 degf above expected at ~615 MWg. $ 42, GENERAL PHYSICS CORPORATION Page 10 of 10