DEAERATOR IN THERMAL POWER PLANT

DEAERATOR AN INTRODUCTION

• Remove dissolved gases.
• Highest vessel in the system.
• Used for heating of feed water.
• Reduce the amount of steam in the system and hence energy flow to the plant.
• Extraction steam enters from the bottom of the tanks.
• Steam passes over the water droplets.
• As the extraction steam condensed the water droplets releases the non-condensable gases vented to the atmosphere.
• The deaerated feedwater & condensed steam mixed and drained out to the FST.
• FST supplies feed water to the boiler feed pumps.
• Acted as an open-type feedwater heater.

CONNECTION

• One pipeline coming from CEP discharge via through ejectors, GSC D/R coolers LPH-1, 2, 3 which supply the water to the Deaerator.
• Two pipelines are connected to the Deaerator which are coming from HPH-5 & HPH -6 drips.
• Two vent pipelines are connected to the Deaerator tank coming from HPH-5 & HPH-6 shell vents. (Since they have high pressure and high temperature i.e. high energy vent so it is supplied to the Deaerator, for saving DM water and utilization of its energy).
• Three lines (in various plant one line) for the boiler feed pump suction for supplying water to BFP (TDBFP  & MDBFP).
• Three lines are connected to the FST which recirculates the water tapped from the discharge line of the boiler feedwater pump (for maintaining minimum flow for BFP),(TDBFP  & MDBFP).
• One Deaerator drain line connected which further goes to the unit flash tank and goes to drain out.
• One deaerator overflow line goes to the LPDFT tank (excess water overflow through this line and goes to hot well).
• On deaerator sampling line which is used for sampling of water.
• A initial heating line to the FST water from the steam taken from LT PRDS.
• Deaerator extraction line coming through the extraction of IPT (this steam is used as deaerating steam). 
• A line from CRH supply the steam for Deaerating.*(* all these three lines are connected through a common header and then goes to the deaerator but from HTPRDS  before the supply valve a line is tapped for initial heating of water into the FST).
• A-line for initial filling is connected to FST for initial filling of FST (it save the energy if filled by CEP).
• A manhole is provided for overhauling and maintenance work in both Deaerator & FST.
• Two standpipes are connected for installments of level transmitters and local gauge glass ( for measuring of the level of deaerator ).
• Also some instruments are installed for temperature, pressure measurement of the system.

DEAERATOR SCHEME