Intermittent blowdown valve MPA / PA up to PN250

Transcription

1 Intermittent blowdown valve MPA / PA up to PN250 Intermittent Blowdown Valve Special Design -Radial Multi-stages Nozzle -Large Opening Area -Spring Closing Force Fail Safe Function Boiler Pressure closes Valve Pneumatic Actuator Possible Function max. 3 Sec. PN DN Boiler water discharge of different valves Page 31 of 74

2 Automated intermittend blowdown system conventional Bottom Blowdown Range up to PN250 Page 32 of 74

3 The Benefits of the New Intermittent Blowdown Valves Improved blowdown effectiveness through integrated pressure chamber in the outlet section of the body Greater tightness through h additional wiper rings between the packing seals Longer service life and availability through radial stage nozzle downstream of the valve seat Insensitive to waterhammer through absence of large body cover Reduced wear through new arrangement of the seals on the low pressure side Consistent t implementation ti of the work safety regulations through h novel distance tube Quick and easy installation thanks to multifunction parts Reduced maintenance and service effort through additional cup springs acting on the compression spring and through the possibility of tensioning the seals from outside Better checking functionally through relief vent for leak detection from outside Greater convenience through innovative clip fastening of the hand lever PA 46/47 Blowdown receiver Flash steam discharge/vent Cooling Water Hot waste water Mixed cooled water Cooling Water Drain Page 33 of 74

4 Boiler blow down with sample cooler For Safety For Accurate Measurement [Result of Lab test from sampling without sample cooler leads to too high TDS, resulting in the excessive blowdown due to loss of flash steam to atmosphere] Excessive Blowdown from sampling without sample cooler Ex : Boiler Pressure 10 barg with boiler TDS = 3500 ppm (mg/l) or TDS / water = 3,500 / 1,000,000 = Sample water from 10 barg to ATM will flash by 16% so water from 1,000,000 kg will be 160, kg of flash steam TDS / water new = 3,500 / 840,000 = Deviation = [ ]x ] / ~ 20% higher h than the fact So if we calibrate TDS from this lab value then the exact value in the boiler is by 2,916 ppm excessive blowdown Energy Loss Page 34 of 74

5 Heat Recovery from Surface Blowdown Flash vessel Page 35 of 74

6 Flash vessel Flash Vessel Design Large diameter Velocity of evaporation rate is m/s to avoid carry over. Condensate inlet over a tangential pipe helps reduce the impact to the vessel. condensate inlet over a tangential pipe Page 36 of 74

7 Heat Recovery Skid ENERGY TECHNOLOGY CO., LTD Heat Recovery from Surface Blowdown ENERGY TECHNOLOGY CO., LTD Page 37 of 74

8 Heat Recovery from Surface Blowdown Heat Recovery from Surface Blowdown Or conductivity (us/cm) Page 38 of 74

9 BA(E) 46 PN40 Surface blow down valve discharge capacity (M)PA46 PN40 Bottom blow down valve discharge capacity Page 39 of 74

10 Heat Recovery from Surface Blowdown x ( )/ = kg/h = 38.76x 24 x 300 kg/year = ton/year 279,072 x4.18 x ( ) kj/year = 90,328,384 kj/year = 90,328, / = ton/year Heat Recovery from Surface Blowdown x 4.18 x ( ) kj/h = 62, kj/h 62,874.41/ kg/h = kg/h = x 24 x 300 k/ kg/year = 202,382.7 kg/year Page 40 of 74

11 Heat Recovery from Surface Blowdown Heat Recovery from Surface Blowdown Page 41 of 74

12 Heat Recovery from Surface Blowdown Sensible heat of blowdown water = x = 204, kj/h at 10 barg ( kj/kg) Sensible heat of drain point of = x 4.18 x 40 = 43,776.3 kj/h blowdown water at 40 C (specific heat of water (C) ~ 4.18 kj/kg) Energy Recovery = 204, , = 160, kj/h Equivalent to 0.3 barg steam = 160, /2, = kg/h (latent heat of steam (r) at 0.3 barg = 2, kj/kg) Equivalent steam saving per year= x 300 x 24 = 517,824 kg/year (steam cost = B/t) = x ~ 510, 118 Baht + Water treatment cost Level Control Monitor Page 42 of 74

13 Water Level Controls The regulations concerning the control of Boilers vary from Country to Country. In general however we can say that most regulations require the Boiler to be fitted with :- Two independent low water alarms A device to control the boilerwater level within specified limits Most regulations also require the Boiler Alarms to be tested daily. Extracted from Transaction Volume 4 Page 43 of 74

14 Water limiter Mechanical Float body magnet magnet switch rod 1 1 measuring chamber float Water limiter Mechanical Float Routine test by pressure or magnetic force Page 44 of 74

15 Water limiter Mechanical Float Problem P bl nott only l ffrom th the moving i partt bbutt also the boiler water quality Float get struck from scale and dirt Pitting (not cause boiler explosion) Pitures extracted from other Safety Technology Bureau/ DIW ENERGY TECHNOLOGY CO., LTD Water limiter Mechanical Float Former German Regulation body magnet switch magnet g rod 1 1 measuring chamber float Owing to the physical measurement principle and the experience obtained in practice, which i also is l reflected fl t d in i the th TÜV ddamage ddata t fil files, additional requirements for the operation were p of the technical issued in the later development rules; these included a reduction of the maximum permissible boiler-water conductivity f from to 8,000 t 300 S/cm, S/ regular l replacement l t of the magnetic switches etc. measures which were intended to pprevent boiler damage g but at the same time in-creased the operating costs ENERGY TECHNOLOGY CO., LTD Page 45 of 74

16 Water limiter Mechanical Float Water limiter Mechanical Float extracted from National Board BULLETIN Issue : winter 1999 Page 46 of 74

17 Water limiter Mechanical Float extracted from National Board BULLETIN Issue : winter 1999 Water limiter Mechanical Float Test Requirement EN for Mechanical Float in EU Float Movement : min 250,000 test cycles Electromechanical switches : min 100,000 cycle Outside float and inside chamber : min 10 mm No float switches for LW in EU Page 47 of 74

18 Developement of boiler control equipment 1969 ER ER 77 MR 16 First self monitoring 1978 ER ER 96 ER 83-3 First Capacitance 1999 NRG NRG 16 SIL3 Measuring Principals Conductive: Low level limiters Multiple tip electrodes Conductivity Control For level detection/control Capacitance: For modulating Level Control Level control It Integrated tdhihl High level lalarm Page 48 of 74

19 Pressure temperature range of Conductive Electrode The conductive probes are available for: PN 6 T max : 156 C / 313 F P max : 6 bar PN 10 T max : 180 C / 356 F P max : 10 bar PN 40 T max : 238 C / 460 F P max : 32 bar PN 63 T max : 275 C /527 F P max : 60 bar PN 160 T max : 311 C / 592 F P max : 100 bar PN 320 T max:: 400 C /752 F P max 183 bar Conductive - Simple low level alarm insulator Isolator Probe tip Meßsp itze Measuring chambermeßgefäß Page 49 of 74

20 Concept Design of Conductivity Electrode Possible danger of limiter with conventional design 2 insulator Probe tip 1 1 Measuring chamber 1 2 Short curcuit by means of deposits condensation after steam penetration Page 50 of 74

21 Simple low level alarm insulator Isolator Probe tip Measuring chamber Meßsp itze Meßgefäß Electrode rod is covered by PTFE to protect the short circuit **spacer to lock for multiple Electrode tip Selection of Controller extracted from National Board BULLETIN Issue : winter 1999 Spacer to lock electrode tips Page 51 of 74

22 Water level limiter special design self monitoring monitoring electrode first insulator second insulator probe tip insulator Monitoring electrode Probe tip State of the Art Technology - Self Monitoring Level Limiter Measured Value Device Status (Alarm, Configuration, Watch Dog) Page 52 of 74

23 Basic of Self Monitoring : Wheatstone bridge R ST = R of insulation across monitoring electrode and boiler shell => insulation check R K = R across monitoring electrode and boiler shell => scale check RP1, RP2 = Fixed R of the design circuit R1/R2 = R3/Rx I G => 0 Failure Dianogsis of Periodic Self-Checking Controller Page 53 of 74

24 Boiler Equipment acc. TRD For boiler operation acc.to TRD 604 (max. 72 hrs without supervision) two self-monitoring low level limiters are required and for boiler operation to TRD602(max. 2 hrs) only one self-monitoring low-level limiter is necessary Boiler Equipment acc.to PED, EN and EN12953 Self-monitoring i equipment with periodic-self checking is required for boilers with temperature/pressure rating > 1 bar and > 120 C and a volume > 50 l Two self-monitoring low-level level for 24 hrs without supervision Function Safety acc.to PED, EN and EN12953 Since the international standards IEC and IEC for functional safety came into effect ec there e has been an ever-increasing e eas demand d for analysing equipment and process instruments that meet the requirements according to SIL (Safety Integrity Level) classification. The European directives EN12952 and demand that a hazard analysis shall be carried out for each limiting device function and appropriate levels of functional safety be Implemented. Note 1 states : Typical Safety Integrity Level (SIL) requirements for boiler protective systems are not less than 2 Page 54 of 74

25 Safety Integrity Level (SIL) Overview Safety Integrity Level (SIL) Overview Page 55 of 74

26 Safety Integrity Level (SIL) Overview Safety Integrity Level (SIL) of low water limiter Page 56 of 74

27 ON-OFF LEVEL CONTROL APPLICATION Pump on/off Low Alarm 2 Multiple tip electrode Pump off Pump on Inside the Spector Compact NRGS 16-2 Page 57 of 74

28 On- Off level control with self monitoring low level alarm On/Off Level Control Advantages Simple, suitable for low capacity boiler(<3-5 t/h), condensate and feed tank Inexpensive for investment Good for stand by boilers. Disadvantages Intense thermal shock stress in the boiler Leads to strongly gymodulating operation of burner Integration into a heat recovery concept or exhaust gas cooling using the economizer principle p is not possible More wear and tear on the feed pump and control gear and burner Variable steam pressure and flow rate. More boiler water carry over. Page 58 of 74

29 Comparison: Intermittend / Continous Intermittend with fixed switch points Continuous with variable switch points High level -Alarm Pump Off Pump On Low level -Alarm High level-alarm Set point Low level - alarm Capacitance level probe Measuring pipe insulator Measuring chamber 20 ma 4-20 ma adjustable for the whole probe length 4 ma plug Page 59 of 74

30 Principle capacitance measurement Principle capacitance level measurement Page 60 of 74

31 Principle capacitance level measurement Capacitive Reactance X C Measurement with Capacitance Probes Low Voltage AC Supply Insulated Probe Rod Current Flows Less Current Flows Liquid in a Metal Vessel Probe Deeply Immersed Current flows due to Capacitance between Probe rod and Water Lower Water Level Less Current Flows Page 61 of 74

32 Level Calibration of Capacitance Probe D W T L = Dielectric D = Steam W = Water T = Teflon L = Air D Probe tip cannot be cut W Durch den Einfluß des Druckes wird der Luftspalt zwischen Teflonisolation und Meßrohr verdrängt Durch den Einfluß der Temperatur längt sich der Teflonschlauch und wird somit dünner Modulating level control-conventional Page 62 of 74

33 Pump speed control with compact probe NRGT 26-1 Frequency driven feedwater control Steam ma Speisewasser Feed water Modulating Level Control Advantages Economic Operation (economizer) Higher steam quality (reduce carry over) Steady steam pressure and flow rate. No strongly modulating operation of burner and more efficient burner operation. Less thermal stress on the boiler shell. Less wear and tear on the feed pump and burner. Capability of adapting to difficult situations regarding the controlled system e.g. sudden change of steam consuption Disadvantages Less suitable for stand by operation. Page 63 of 74

34 Influence of the boiler capacity on the low level switchpoint Main steam valve Low level limiter Main steam valve Low level limiter Steam area Steam area Combustion tube Fire tube Shell boiler without steam production Shell boiler with steam production Sudden increasing steam consumption in the boiler leads to : Pressure drop in the boiler Extension of steam bubbles Increasing water level Closure of the control valve Pressure drop leads to increasing burner output Steam bubbles are compressed Water level decreases partial below low level Boiler is shut down due to low level alarm! Remedy???? Page 64 of 74

35 Mode of Boiler Operation Sudden increase in steam consumption Boiler performance during feedwater filling without economizer Operation at higher level or lower pressure of boiler design. Three elements control for sudden change of steam consuption Three element control D TIC LIC N Boiler W Page 65 of 74

36 Boiler equipment with SPECTORbus Recommendation for installation 40 mm Page 66 of 74

37 Recommendation for installation 40 mm Self monitoring External Low Level Limiter Risks with external measuring pots : Stop-valve blocking Mud inside level pot Failure in changing level l detection Page 67 of 74

38 Level probe installed in an external measuring pot with SRL Level probe installed in an external measuring pot with SRL Page 68 of 74

39 Compact Design and compatible to conventional systems Easily accessible connection terminals Compact Design and compatible to conventional systems Supply voltage 24 VDC, improved EMC control (other voltages with separate power unit) Switchable sensitivity : 0.5 or 10 μs/cm Supply via reliable networks possible without additional component (inverters) Intuitive operating using rotary pushbutton or color touch display SPECTORmodule Touch with separate control unit and greatly extended functionality Now also as modulating controller and three-element control All limiter systems with SIL3 certification SPECTORmodul TOUCH Continous level controller NRR 2-52 Page 69 of 74

40 Screen shots of NRR 2-52 operating unit URB 50 Screen shots of NRR 2-52 operating unit URB 50 Page 70 of 74

41 Condensate Monitoring Diffuse or stray light in water 90 Streulicht Scattering light Opto transmitter Lichtsender Lichtempfänger 15 Streulicht Opto reciver Lichtempfänger Durchlicht Opto reciver Scattering of solids 90 Scattering of oil 15 Streuung von Feststoffen, daher Hauptanwendungsgebiet in der Trinkwasser-Aufbereitung / -Versorgung Streuung von Öltropfen, daher Anwendung des 15 Steulichtverfahrens zur Ölerkennung Page 71 of 74

42 Functional principle of the OR Automatische Kompensation von Störgrößen wie: Verfärbung Lampenalterung Verschmutzung der Gläser Automaticly compansation of Variable disturbance T V Alarm Ventil Umschaltung Alarm Valve switch over 3 12 V Istwert X Actual value Sollwert W Setpoint Lampenspannung 12 V Voltage 12 V Saving from Condensate Return Condition : Condensate 1 t/h, P1 = 5 barg, P2 = 0.3 barg Sensible heat of blowdown water = 1,000 x 671 = 671,000 kj/h at 5 barg (671 kj/kg) Feed water temp 30 C = 1,000 x 4.18 x 30 = 125,400 kj/h (specific heat of water (C) ~ 4.18 kj/kg) Energy Recovery = 671, ,400 = 545,600 kj/h Equivalent to 0.3 barg steam = 545,600 /2, ~ 244 kg/h (latent heat of steam (r) at 0.3 barg = 2, kj/kg) Equivalent steam saving per year= 244 x 300 x 24 = 1,756,800 kg/year (if steam cost = 1,000 B/t) = 1,756.8 x 1,000 ~ 1,756, 800 Baht + Water treatment cost Page 72 of 74

43 Example of saving from condensate return Example of saving from condensate return Page 73 of 74

44 Page 74 of 74