Allen ppt on evacuation system (1).dgpptx

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1. EVACUATION SYSTEM Presented by ALLEN ERIC BECK

2. TOPICS What is Vacuum How Vacuum is created Why Vacuum is Importance in Condensing System Vacuum Producing device Working and Specification Effect of over Vacuum Effect of under Vacuum Causes & Rectification of Low Vacuum in Condenser

3. What is Vacuum Bellow Atmospheric pressure is Known as vacuum How Vacuum Is Created A vacuum can be created by removing air from a space using a vacuum pump or by reducing the pressure using a fast flow of fluid

4. Why Vacuum is Importance in Condensing System A Vacuum Is maintained in condenser so that Steam can easily flow . More work can be extracted from the steam in the turbine . The Pressure in the last stage of the steam in the turbine is very low after performing the work, To make the steam flow to the condenser to convert into condensate (liquid/water) it is necessary that the pressure be much lower in the condenser to make the system flow to the condenser

5. Vacuum Creating device Steam Jet Ejector System Liquid Ring Vacuum Pump

6. Liquid Ring Vacuum Pump The liquid ring vacuum pump is a specific form of rotary positive-displacement pump utilizing liquid as the principal element in gas compression. The working parts of the liquid ring vacuum pump consist of a multi bladed impeller mounted eccentrically in a round casing which is party filled with liquid. As the impeller rotates, the liquid is thrown by centrifugal force to form a liquid ring which is concentric with the periphery of the casing.

7. Normal Operating Parameter Parameter Value Vacuum Pump Current 72 Amps System Vacuum -90.50 kpa Vacuum Pump Separator level normal 200 mm (50%) Vacuum Pump Separator temp. <40 deg c Alarm/Trip/Interlock Setting Description Value Vacuum Pump Separator level normal 40mm (<20%) alarm Standby Vaccum Pump Auto pickup at -85 kpa TG will be Trip on Vacuum LL - 72 kpa

8. Specification Make M/s Denever Nash Machinery ltd Type Liquid-Ring Vacuum Pump (TC-11E) Model AT1006E No. of Pump 2*100% Pump Rated speed 740 RPM No. of stage 02 stage water loop type Vacuum Pump Operating Liquid Water Direction of Rotation Anti-clock wise(Facing DE shaft end) Air Extraction Capacity >30.6 kg/h Suction Pressure 2900 pa

9. Causes Rise in CW temperature . Tripping of CT fans . Air ingress in a condenser. Vacuum pump tripping . Loss of Seal/make up to vacuum pump . Seal steam pressure is low . (design pr. 20kpa) Failure of CW pumps . Opening of vacuum breaker valve . Failure of gland sealing water. Condenser hotwell level high. Gland steam dump valve going full open at reduced load .

10. Immediate Action Start second vacuum pump if not started on auto. Check level of seal water to vacuum pump . Start stand by CW pump if running pump is tripped stand by not started in auto . Check CT Fan and Start. Check Gland seal steam pressure. Check LP Exhaust Hood temp. Reduce hot well level if level is very high. Reduce boiler firing if vacuum is not improving

11. Effect of over vacuum and Effect of under vacuum Over Vacuum- It causes sub-cooling effect where hot well temperature reduces more than design which required to be added in boiler leads to heat loss . Boiler Efficiency is decreased due to lower condensate Temperature. Exhaust steam Flow Increases erosion in LPT last stages. Due to high vacuum Vibrations increases in Turbine Under vacuum- LPT efficiency reduction which causes lesser work done & leads to reduced load output.

12. Thank you