Advance Boiler Control System

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GESTRA Steam SystemsGESTRA

Intermittent blowdown valve MPA / PA up to PN250

IntermittentIntermittent BlowdownBlowdown ValveValve Special Design

-Radial Multi-stages Nozzle--Spring Closing Force

Fail Safe Function Boiler Pressure closes Valve Pneumatic Actuator Possible

. .

PN 40-250 DN 20-50

ENERGY TECHNOLOGY CO., LTD.0-2721-3860


Boiler water discharge of different valves

ENERGY TECHNOLOGY CO., LTD.0-2721-3860Page 31 of 74


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Automated intermittend blowdown system conventional



Bottom Blowdown Range up to PN250



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The Benefits of the New GESTRA Intermittent Blowdown Valves

Improved blowdown effectiveness through integrated pressure chamber in the outletsection of the body rea er g ness roug a ona w per r ngs e ween e pac ng sea s Longer service life and availability through radial stage nozzle downstream of the valveseat Insensitive to waterhammer through absence of large body cover Reduced wear through new arrangement of the seals on the low pressure side ons s en mp emen a on o e wor sa e y regu a ons roug nove s ance u e Quick and easy installation thanks to multifunction parts Reduced maintenance and service effort throu h additional cu s rin s actin 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



Blowdown receiver

Cooling Water

Cooling Water

Mixed cooled water

Drain



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Boiler blow down with sample cooler

For Safety

[Result of Lab test from sampling

high TDS, resulting in the excessive

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 = 0.0035

Sample water from 10 barg to ATM will flash by 16%so wa er rom , , g w e , g o as s eamTDS / water new = 3,500 / 840,000 = 0.0042

ev a on = . - . x . ~ g er an e ac

boiler is by 2,916 ppm excessive blowdown Energy Loss



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Heat Recovery from Surface Blowdown



Flash vessel



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Flash vessel


GESTRA Flash Vessel Design

Velocity of evaporation rate is. - . m s o avo carry over.

Condensate inlet over a

Large diameter

the impact to the vessel.

condensate inlet over



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Heat Recovery Skid






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Or conductivity (uS/cm)



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BA(E) 46 PN40 Surface blow down valve discharge capacity


(M)PA46 PN40 Bottom blow down valve discharge capacity



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261.82 x (781.66-450.51)/2236.86

= . g

= 38.76x 24 x 300 kg/year

= 279.07 ton/ ear

279,072 x4.18 x (107.434 - 30) kJ/year

= 90,328,384 kJ/year


= , , . = . on year



223.06 x 4.18 x (107.434 - 40) kJ/h

= 62,874.41 kJ/h

62,874.41/2236.86 kg/h

= 28.11 kg/h

= 28.11 x 24 x 300 kg/year = 202,382.7 kg/year



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Sensible heat of blowdown water = 261.82 x 781.66 = 204,654.22 kJ/h

at 10 barg (781.66 kJ/kg)Sensible heat of drain point of = 261.82 x 4.18 x 40 = 43,776.3 kJ/h

‘ (specific heat of water (C) ~ 4.18 kJ/kg)

= - = , . , . , .

Equivalent to 0.3 barg steam = 160,877.92 /2,236.86 = 71.92 kg/h= . , .

Equivalent steam saving per year= 71.92 x 300 x 24 = 517,824 kg/year (steam cost = 985.12 B/t) = . x .

~ 510, 118 Baht + Water treatment cost



Level Level Control Control

Monitor Monitor

Page 42 of 74


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Water Level Controls

The regulations concerning the control of Boilers vary from

.regulations require the Boiler to be fitted with :-

• Two independent low water alarms

• A device to control the boilerwater level

os regu a ons a so requ re e o er arms o e

tested daily.



Extracted from Transaction Volume 4Page 43 of 74


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Water limiter – Mechanical Float

body

magnet

magnet switch

11

rod

measuring chamber

float






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ro em no on y rom e mov ng par ualso the boiler water quality

Float get struck from scale and dirt

Pitures extracted from other Safety Technology Bureau/ DIW



Former German Re ulationWater limiter – Mechanical Float

body

ma netmagnet switch

Owing to the physical measurement principle

and the experience obtained in practice, which

11

rods a so re ec e n e amage a a es,additional requirements for the operation wereissued in the later develo ment of the technical

measuring chamber rules; these included a reduction of themaximum permissible boiler-water conductivity

floatrom , o cm, regu ar rep acemenof the magnetic switches etc. – measureswhich were intended to revent boiler dama e

but at the same time in-creased the operatingcosts



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extracted from “National Board BULLETIN“ Issue : winter 1999



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Test Requirement EN 1295-9 for Mechanical Float in EU

Float Movement : min 250,000 test cyclesElectromechanical switches : min 100,000 cycleOutside float and inside chamber : min 10 mm

No float switches for LW in EU



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Developement of GESTRA boiler control equipment

2010

NRG 261981

ER 961978ER 55

19771972

1980ER 83-3

SIL3

MR 16First self monitoring

ER 14



Measuring Principals

Low level limiters

Conductivity Control

apac ance: or mo u a ng eve on ro Level control

n egra e g eve arm



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PN 6 Tmax: 156°C / 313°F Pmax: 6 bar



° ° max max


PN 320 T 400°C /752°F P 183 bar



Conductive - Simple low level alarm

Isolator insulator

Meßspitze



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Concept Design of Conductivity Electrode



Possible danger of limiter with ‘‘conventional design“

insulator

11

Probe tip

easur ng c am er

Short curcuit by means of deposits1

condensationafter steam penetration2



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Simple low level alarm

Isolator insulator

Meßspitze Electrode rod is covered byPTFE to protect the short circuit

**spacer to lock for multipleElectrode tip



Selection of Controller


Spacer to lock electrode tips



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Water level limiter ”special design” self monitoring

monitoring electrode

rs nsu a or

second insulator

Monitoring electrodeinsulator

Probe tip



State of the Art Technology - Self Monitoring Level Limiter

Value

DeviceStatus(Alarm,

,

Watch Dog)



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Basic of Self Monitoring : Wheatstone bridge

RST = R of insulation across monitoring electrode

IG => 0and boiler shell => insulation checkRK = R across monitoring electrode and boiler shell=> scale check

RP1, RP2 = Fixed R of the design circuit



Failure Dianogsis of Periodic Self-Checking Controller



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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 toTRD602(max. 2 hrs) only one self-monitoring low-level limiter is necessary

Boiler Equipment acc.to PED, EN 12952 and EN12953

e -mon or ng equ pmen w per o c-se c ec ng s requ re or o erswith temperature/pressure rating > 1 bar and > 120’C and a volume > 50 l

- -



Function Safety acc.to PED, EN 12952 and EN12953

Since the international standards IEC 61508 and IEC 61511 for functionalsafet came into effect there has been an ever-increasin demand foranalysing equipment and process instruments that meet the requirements

accordin to SIL Safet Inte rit Level classification. The Euro ean directivesEN12952 and 12953 demand that a hazard analysis shall be carried out foreach limiting device function and appropriate levels of functional safety beImplemented.Note 1 states :” Typical Safety Integrity Level (SIL) requirements for boilerprotective systems are not less than 2”



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Safety Integrity Level (SIL) Overview




Page 55 of 74


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Safety Integrity Level (SIL) of GESTRA low water limiter



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ON-OFF LEVEL CONTROL APPLICATION

Pump on/off

Pump off

Low Alarm 2



Inside the Spector Compact NRGS 16-2



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On- Off level control with self monitoring low level alarm



On/Off Level ControlAdvantages

Sim le suitable for low ca acit boiler


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Comparison: Intermittend / Continous

Intermittend with fixed switch points Continuous with variable switch points

High level -Alarm

Pump Off

High level-Alarm

Pump OnSet point

Low level -Alarm Low level - alarm



Capacitance level probe

Measuring pipe20 mA

insulator 4-20 mA adjustablefor the whole probelength

Measuring chamber

4 mA

plug



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Principle capacitance measurement



Principle capacitance level measurement

Page 60 of 74


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Principle capacitance level measurement

Capacitive Reactance XC



Measurement with Capacitance Probes

Low Voltage

AC Supply

CurrentFlowsInsulated

Probe

Less CurrentFlows

Rod

Liquid

in a

Metal

Vessel

Probe Deeply Immersed Lower Water Level

between Probe rod and Water Less Current Flows

Page 61 of 74


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Level Calibration of Capacitance Probe

D

= Dielectric

W

T

L

W = Water

T = Teflon

L = Air

Probe tip cannot be cutD

Durch den Einfluß des Druckes wird derLuftspalt zwischen Teflonisolation undMeßrohr verdrängt

W

Durch den Einfluß der Temperatur längtsich der Teflonschlauch und wird somitdünner



Modulating level control-conventional



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Pump speed control with compact probe NRGT 26-1

Frequency driven feedwater control

4...20 mA

Speise-wasser Feed water



Modulating Level Control

van ages

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 b ’ o eration.



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Influence of the boiler capacity on the low level switchpoint

Main steam valve Main steam valveLow level limiter 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

Increasing water level

Closure of the control valve

Pressure drop leads to increasing burner output

Steam bubbles are compressed

Boiler is shut down due to low level alarm !

Remedy ????



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Mode of Boiler Operation

Sudden increase in steam consumption

economizer

.

Three elements control for sudden change of steam



Three element control

D

NLIC

Boiler

W



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Boiler equipment with SPECTORbus


Recommendation for installation 40 mm



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Recommendation for installation 40 mm



„Self monitoring“ External Low Level Limiter

Risks with externalmeasuring pots :

• Sto -valve blockin

• Mud inside level pot

• a ure n c ang ng evedetection

Page 67 of 74


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Level probe installed in an external measuring pot with SRL



Level probe installed in an external measuring pot with SRL



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Compact Design and compatible to conventional systemsEasily accessible connection terminalsCompact Design and compatible to conventional systemsSupply voltage 24 VDC, improved EMC control (other voltages with separate power unit)Switchable sensitivity : 0.5 or 10 µS/cm

Intuitive operating using rotary pushbutton or color touch displaySPECTORmodule Touch with separate control unit and greatly extended

functionalityNow also as modulating controller and three-element controlAll limiter systems with SIL3 certification


SPECTORmodul TOUCHContinous level controller

-



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Screen shots of NRR 2-52 operating unit URB 50



Screen shots of NRR 2-52 operating unit URB 50



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Condensate Monitoring



Diffuse or stray light in water

90° Streulicht Scattering light

Lichtempfänger

15° Streulicht O to reciver

Lichtsender

Lichtempfänger Durchlicht Opto reciver

O to transmitter

Streuung von Fe ststoffen, daher Hauptanwend ungsgebiet in der Scattering of solids 90°Trinkwasser-Aufbereitung / -Versorgun g

Streuung von Öltropfen, daher Anwendung desScatterin of oil 15° teu c tver a rens zur er ennung



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Functional principle of the OR

Automatische Kompensation von Störgrößen wie: Verfärbung

Lam enalterun

Automaticly compansation of

Variable disturbance Verschmutzung der Gläser

VentilUmschaltung

AlarmTV AlarmValve switch over

3 – 12 V

X Actual valueSollwert

W Setpoint

Lampenspannung12 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 tem 30’C = 1 000 x 4.18 x 30 = 125 400 kJ/h (specific heat of water (C) ~ 4.18 kJ/kg)

= - = , , ,

Equivalent to 0.3 barg steam = 545,600 /2,236.86 ~ 244 kg/h . , .

Equivalent steam saving per year= 244 x 300 x 24 = 1,756,800 kg/year

(if steam cost = 1,000 B/t) = , . x ,~ 1,756, 800 Baht + Water treatment cost



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Example of saving from condensate return



Example of saving from condensate return



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Advance Boiler Control System

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