Electraulic Vs Hydraulics Steam Turbines


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Alternative to control oil system and servo valve control of steam turbines

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Electraulic Vs Hydraulics Steam Turbines

  1. 1. Actuator Hydraulic Circuits<br />All basically the same<br />Must have oil tank<br />Constant oil pressure<br />Oil drains to tank<br />System is naturally dirty <br />Water and Air ingress cannot be avoided<br />System is hyper sensitive to oil contamination<br />
  2. 2. Proportional Valve<br />Let’s Have a Closer Look<br />SERVO VALVE <br />
  3. 3. Servo/Proportional Hydraulics<br />This technology is utilized for some of the most critical positioning applications. <br />The capabilities exceed the requirements for Steam turbine governor, speed/load control & trip speeds.<br />
  4. 4. Hydraulics for Valves and IGV’s<br />The control capabilities exceed the requirements<br />Pneumatic and electric technology typically cannot meet the requirements<br />There is a large gap in the performance of servo hydraulics vs pneumatics.<br />
  5. 5. Hydraulic System Control valves<br />All Require Extreme Fluid Cleanliness<br />All Require Fine Oil filtration<br />Servo Valve<br />ISO 18/15/12<br />Proportional Valve<br />ISO 19/16/13<br />
  6. 6. OIL CLEANLINESS<br />Over 80% of hydraulic failures are a result of dirty oil<br />Four major causes of hydraulic oil deterioration: <br /> 1) Moisture (water in oil) <br /> 2) Particulate Matter (from system or “new” oil) <br /> 3) Acid build-up (caused by moisture)<br /> 4) Oxidation (caused by air and heat)<br />
  7. 7. OIL CLEANLINESS<br />Is critical for servo/proportional hydraulic system performance <br />Must be cleaner than ISO 18/15/12 - NAS Class 6 to avoid failure of servo valves and ISO 19/16/13 – NAS Class 7 for proportional valves<br />New oil must be filtered prior to use (“new” oil is 23/21/18 - NAS Class 12 – considered “dirty”)<br />
  8. 8. OIL CLEANLINESS<br />Conventional Hydraulic systems (servo and proportional) are “Open-Circuit” hydraulic systems (they draw/drain to/from oil tank)<br />These systems communicate with atmosphere – allowing water and air to contact the oil<br />Water and Air are the main the contributing factors to oil contamination<br />
  9. 9. OIL CLEANLINESS<br />Heat build up accelerates the breakdown of oil… especially when it is contaminated with water and air<br />Servo valves require full system pressure at all times in order to control properly<br />Maintaining continuous oil pressure requires continuous circulation of oil<br />Continuous circulation of pressurized oil causes heat rise in the oil (due to pressure and friction in the hydraulic lines)<br />
  10. 10. OIL CLEANLINESS<br />Hydraulic systems must combat oil breakdown and maintain superclean oil levels to avoid failures<br />In order to do this complex fluid filtration systems are implemented<br />Oil sampling, filter maintenance, oil flushing, and oil replacement must be done regularly<br />
  11. 11. OIL CLEANLINESS<br />Count the filters<br />There are 6 filters used. These filters absorb moisture and dirt. They must be replaced regularly or system will fail<br />
  12. 12. Control is Great but Cost and Maint are high:<br />Electro-hydraulic actuators have historically been used only on the applications with the most critical control requirements<br />Power plants must live with the high cost and maintenance of these systems in order to effectively control steam turbines <br />Or do they?.....<br />
  13. 13. OIL CLEANLINESS – What if?<br />What if oil cleanliness did not have to be monitored?<br />What if the source of oil contamination and breakdown were eliminated by design?<br />What if no oil sampling, filter maintenance, oil flushing or oil replacement were required?<br />What if a hydraulic system were designed that required no filters or oil replacement… ever?<br />
  14. 14. Development of the Next Generation Hydraulic Actuator System<br />Development in U.S. (near Boston) from 1981 – 1989.<br />Work centered on revolutionary flow circuit called the Flow Match Valve “FMV” and a positive displacement gear pump<br />This FMV eliminates servo and proportional valves<br />It is a “modified” pilot operated piston check valve<br />
  15. 15. How Can We Improve on conventional hydraulic technology?<br />By maintaining the strengths and eliminating the weaknesses of conventional hydraulic systems<br />
  16. 16. The Answer: “Electraulics”<br />“Electraulics” is the word we use to describe our patented, self contained, electro-hydraulic actuator technology.<br />During development of this technology, effort was made to eliminate the weaknesses of servo/proportional hydraulic systems but retain the strengths.<br />
  17. 17. Design Criteria<br />Electrically driven<br />Microprocessor based<br />Mechanically simple (few moving parts)<br />Capable of continuous operation (100% duty)<br />Capable of precise positioning regardless of valve friction or process dynamics<br />Low Power consumption<br />Fail-safe option<br />Compact<br />Eliminate oil tank<br />
  18. 18. This is why REXA is different<br />
  19. 19. FMV1<br />Closed-Loop Hydraulic Circuit<br />FMV2<br />
  20. 20. Flow Match Valve Operation<br />*FMV is flow activated. Once motor/pump moves, FMV’s open<br />*FMV’s control the flow of oil in a smooth and stable manner regardless of the direction or magnitude of the applied load<br />*The pump is positive displacement. It generates only the pressure required to move the load (cylinder)<br />Demo Program<br />Theory of Operation<br />
  21. 21. Other Modulating Hydraulic Actuators<br />REXA has none of these characteristics<br />Have a gravity fed reservoir tank (hundreds of liters)<br />Drain to reservoir when cylinder moves<br />Take oil from reservoir when the motor/pump activates<br />Have particulate filters that must be monitored and replaced<br />Must periodically have oil flushed or changed<br />Must use heaters and desiccant filters to keep water out of oil<br /> (condensation)<br />Has 60cc spring-loaded oil expansion chamber<br />Does not use a reservoir<br />Does not require fluid filtration<br />Does not require oil flushing or changing<br />Does not require condensation heaters or desiccant filters<br />
  22. 22. Conventional Hydraulic System vs REXA<br />FMV eliminates all of this.<br />Reservoir Tank and filtration System Not Required with FMV Circuit<br />FMV Circuit: Motor/Pump/FMV’s<br />To/From cylinder<br />From/To cylinder<br />
  23. 23. FMV Greatly simplifies hydraulic system<br />Flow Matching Valve System<br />Replaces: Oil Tank, Proportional valves, Solenoid Valves and Block Valves<br />
  24. 24. THE FLOW MATCH VALVE CIRCUIT<br />Eliminates the possibility of water and air contamination<br />Closed loop<br />Purged (no air)<br />Positive Pressure at all times<br />Air/Water cannot enter the hydraulic circuit – BY DESIGN<br />
  25. 25. FLOW MATCH VALVE CIRCUIT<br />Not susceptible to failure caused by particulate matter in “new” oil<br />Particulate size that can pass through system is greater than 25/21/18 (NAS 12)<br />This is the cleanliness rating of new oil prior to extensive filtration required by servo or proportional valves<br />
  26. 26. FLOW MATCH VALVE CIRCUIT<br />Oil does not break down, why?<br />Impossible for air or water to contaminate system<br />Oil does not heat up, why?<br />Motor/pump only activate when a position change is required<br />Positive displacement pump only generates enough pressure to move load<br />
  27. 27. The FLOW MATCH VALVE CIRCUIT<br />Provides excellent performance (0.1%, etc)<br />Eliminates the control oil system<br />Eliminates ALL Filters and filter maintenance<br />Eliminates ALL oil flushing and replacement<br />Reduces System Oil volume by 95%<br />
  28. 28. REXA circuit with Spring-fail<br />
  29. 29. REXA circuit with Accumulator Fail<br />
  30. 30.
  31. 31. Accumulator:Fail Mode<br />
  32. 32. Accumulator: Charging Mode<br />
  33. 33. EH actuator Hydraulic Circuit<br />Electraulic Circuit<br />FMV eliminates all of this<br />
  34. 34. Steam Turbine<br />Servo Valve, Filtration Module, Hydraulic motor (left)<br />REXA Equivalent.<br />NOT REQUIRED: Servo valve, Filtration system or Control oil System with HPU Tank.<br />Servo, Filters, HPU System, Turbine valves<br />
  35. 35. STEAM TURBINE INSTALLATIONS<br />Approximately 700 actuators installed<br />Turbines ranging in size from 5MW to 640MW<br />Steam Turbine Driven compressors, pumps & fans / Main Steam Generators <br />Applications: Governor, Speed/Load Changers, Stop Valves, Trip/Throttle Valves, Steam Gland Seal<br />Approximately 12 different steam turbine manufacturers<br />Approximately 200 different steam turbine models<br />Currently working on MHI feedpump turbine retrofit in Taiwan<br />
  36. 36. Original ST Hydraulic System with Control Oil System<br />
  37. 37. Elimination of Control Oil System<br />
  39. 39. Allis Chalmers BFPT’s – U.S.<br />REXA replacement – no control oil required (1 sec throttling speeds, 0.2 sec trip)<br />Original pilot/relay actuator powered by control oil system<br />
  40. 40. Delaval Boiler Feedpump Turbines – 800MW CE Supercritical Plants<br />REXA direct replacement for pilot/relay control (1 sec modulating speeds, 0.2 sec trip)<br />Original Woodward EG model removed (8 units total)<br />
  41. 41. Boiler Feedpump Turbines at largest fossil plant in U.S. (W.A. Parish)<br />Directly replaces Woodward TM25 actuator for control of pilot/relay valve.<br /> (5 sec modulating speed, no trip required. 6 units total)<br />
  42. 42. BFPT HP Governor and HP ESV – 500MW Units (OPG – Canada)<br />Replaced original servo controlled hydraulics.<br />Boiler Feedpump Turbine<br /> 1 sec modulating speed, 0.5 sec trip<br />
  43. 43. Age Refining, TX, USA<br />Direct drive linear. Replacement of original servo hydraulic system. Dresser Rand upgrade of WH steam turbine.<br />1 sec/in modulating speed (3” total travel), 0.5 sec full stroke trip speed. Surge software for 0.5 sec partial stroke trip w/no overshoot<br />CSA Class 1 Div 2 actuator, Nema 4X enclosure<br />
  44. 44. Steam Turbine Driven Oxygen Compressors – Refinery, S. Africa<br />Direct rotary shaft drive.<br />Replacement of Moog servo hydraulic system <br />BBC Steam turbine driven Oxygen compressors. <br />7200rpm rated machines run at 7000rpm. REXA controls +/-1 rpm (0.1% actuator deadband).<br />270 degree rotation. 4 second modulating speeds with 1 second accumulator trip speed. <br />REXA’s also installed upstream on Stop Valves with 0.3 sec trip speed (see next slide).<br />7 steam turbines retrofit<br />
  45. 45. Steam Turbine Driven Oxygen Compressors – Refinery, S. Africa<br />REXA replacement (retrofit) onto Steam Turbine Quick-Closing/Stop Valve.<br />0.4 sec trip speed (bench), 0.15 sec trip speed installed (with steam flow assisting valve).<br />REXA installed on both governor and stop valve allows plant to eliminate hydraulic control system and improves machine safety & reliability. Contaminated oil can cause stop valve to stick (not actuate in overspeed condition)<br />15,000 lbs (67kN) cylinder force<br />4500 lbs (20kN) spring force on seat<br />3” (75mm) travel<br />7 steam turbines retrofit<br />Original BBC Steam Turbine Quick-Closing/Stop Valve<br />(right side)<br />
  46. 46. Steam Turbine Driven Oxygen Compressors – Refinery, S. Africa<br />REXA replacement of servo <br />hydraulic system<br />Governor/Speed valve (right side)<br />Quick-Closing/Stop valve (left side)<br />
  47. 47. Steam Turbine Driven Ethylene Compressors – Refinery, S. Africa<br />Trip & Throttle (T&T) Valves<br />Servo hydraulic system replacements<br />(1 sec modulating speed, 0.5 sec trip speed)<br />13,000rpm rated machines operated at 11,200rpm<br />+/- 1 rpm speed control with REXA<br />4 steam turbines retrofit<br />Zone 2<br />
  48. 48. Steam turbine driven hydrogen compressors - Before<br />Original Actuators:<br />Governor actuator – Woodward through lever (bottom)<br />Emergency Stop Valve – Shin Nippon Machinery (left side)<br />Refinery – Zone 2 area<br />
  49. 49. Steam Turbine Driven Hydrogen Compressors - After<br />Woodward and Shin Nippon Machinery actuators replaced by REXA<br />Governor: 1 sec modulating speed, 0.2 sec trip speed<br />Stop valve: 0.18 sec trip speed (bench). <br />Zone 2 <br />
  50. 50. Steam Turbine Driven boiler feedpump350MW power plant – Lake Hubbard, TX - USA<br />Woodward TM25 model<br />Replaced by REXA<br />Woodward actuator required rebuild or replacement every 6 months<br />REXA replacement operated for 9 years continuously with no maintenance<br />
  51. 51. Overall photo of MBFT (Woodward replacement)<br />
  52. 52. Refinery Compressor IGV – Ingersoll Rand REXA Replaced pneumatic actuator<br />
  53. 53. Standard OEM packages for Turbine & Compressor Applications<br />
  54. 54. Main STEAM GENERATORS<br />
  55. 55. Governor Control<br />Governor Control - Pilot/Relay valve for small steam turbine (5MW)<br />US Navy Base<br />Governor Control – Pilot/relay valve<br />12MW Extraction Turbine - China<br />
  56. 56. GE 1150MW Supercritical Turbine<br />REXA replacement<br />Original actuator (above)<br />
  57. 57. GE 1150MW Supercritical Turbine<br />
  58. 58. Westinghouse 125MW ST<br />
  59. 59. Westinghouse 125MW Speed/Load Governor<br />Actuator controls hydraulic pilot relay valve. Replaces electric motor/worm gear & Woodward type actuators<br />
  60. 60. Westinghouse 125MW Speed/Load Governor<br />Retrofit Results: Ramp Rate increase from 2MW/min to 10MW/min<br />
  61. 61. GE Governor Control<br />Replaces original mechanical governor system<br />(3 sec modulating speeds, 0.1 sec trip)<br />
  62. 62. REXA controls hydraulic “servo”/directional valve. Full redundant actuator. <br />1 sec modulating speed (used at start-up), 0.3 sec trip. Replaces Woodward actuator<br />GE 300MW – Servo Control of Stop Valve<br />
  63. 63. GE Main Steam Turbine Trip & Throttle<br />(3 sec modulating speed, 0.1 sec trip)<br />Full redundant actuator<br />GE Servo Control of Stop Valve<br />
  64. 64. Steam Turbine Governor Valves – Power plant in RefineryOriginal servo hydraulic system to be replaced by REXA<br />4 governor valves per turbine<br />10 turbines<br />
  65. 65. Steam Turbine Governor Valves – Power plant in RefineryREXA retrofit – 2 sec modulating speed, 0.3 sec trip (spring-fail)<br />
  66. 66. Governor/Pilot Valve retrofit<br />With Remote Mounted motor/pump<br />
  67. 67. Compare Servo/Proportional Electro-hydraulic<br />Like electro-hydraulic, electraulicactuators<br /> 1.) Provide quick, precise response<br /> 2.) Supply “inherently stiff” positioning<br /> 3.) Have fail-safe option<br />Unlike electro-hydraulic, electraulic actuators<br /> 1.) Do not have continuously running motors<br /> 2.) Do not require fluid filtering systems<br /> 3.) Do not require routine maintenance (no oil changes)<br /> 4.) Do not have high volumes of fluid (20X less)<br />
  68. 68. THE FACT IS…<br />Improved Process (Plant) efficiency($$) depends as much on improved actuation as it does on improved instrumentation.<br />This has been proven by REXA in virtually every process industry.<br />
  69. 69. Koso America…Home of REXA Actuators and Drives<br />
  70. 70. Sample Installation Photos<br />Conventional Hydraulic actuator system for gas turbine fuel control.<br />REXA on GE Frame 5 Fuel Gas Valve. No hydraulic system required<br />Actuator (left)<br />Hydraulic System required to power actuator (below)<br />