BALANCE WORK OF BOILER PART -I SSOT BLOWER , CC PUMP -ABC OF THERMAL POWER PLANT

Till date I have covered important aspects of Boiler erection and commissioning item wise .

However there are few other items also which are needed for a Power Plant more than 500MW.

Items like soot blower system , Boiler water Circulating Pump system , steam blowing process,

safety valve setting process etc. There are many other process and items required for the Power

Plant which cannot be accommodated in blogs . However steam blowing and safety valve floating

will be discussed after I complete TG package .

SOOT BLOWING SYSTEM

There are three types of soot blower in a Boiler.

a. Wall Des lager - Small size soot blowers mounted on water wall to clean water wall externally

from the deposition of soot by using steam jet.

b. LRSB ( Long retractable soot blower ) mounted on water wall surface having long lance to

carry out soot clean process on different super heaters.

c. Air heater soot blowers for Air heater regions soot cleaning.

When Hydro test is over soot blowers are erected in the boiler . Pipe lines are connected after that.

During commissioning  rotary and transverse movement are checked . Distance between lance tip

head and pressure part wall is checked. In our case distance is 38 mm for wall soot blower.

Pressure setting is also done for individual air heater.

Air heater soot blower is required during Boiler light up as chances of soot deposition is high

at air heater basket. Oil is used during Light up and chances of oil soot deposition is high and

it is potential fire hazard afterwards.

Air heater soot blower operates once in 8 hour shift. Other soot blower operates once in 24 hours.

Soot blower controls commands the sequence of operation in the boiler.

Effective cleaning will give clean surface and good heat transfer.

Fuel consumption will be less and production cost will be less. 

CC PUMP

In a controlled circulation Boiler, circulating pumps plays an important role in the performance of the

Boiler.  For 500 MW Units, 3 Numbers of circulating pumps are given and these pumps are placed in

the down comer circuits to ensure proper circulation  of water through the four  water walls. For

250MW/300 MW and below waters moves in natural circulation but for 500MW and above forced

circulation is necessary. For supercritical boilers for initial stage one number cc pump is required.

Feed water entering the boiler drum via Economiser, flows from the drum through the down comers ( 6

Number) to the pump section manifold.  The boiler circulating pumps takes water from the suction

manifold and discharges via the pump discharge  lines in to the furnace lower front inlet header,

furnace lower water wall right and left side headers and rear headers.

In the water wall inlet header, the boiler water passes through strainers and then through orifices which

feed the furnace wall tubes, the economizer recirculating lines.

Associated systems are as follows

a)     Fill and purge line system

This system consists of supply lines from High Pressure water source and also low pressure water

source, removable strainer basket, HP fill and Purge cooler, filter, orifice and all connected lines

both inlet and outlet circuits.  The removable strainer basket and HP fill and purge cooler are

common for all the three circulating pumps.

b)Auxiliary cooling water system

This system is supplied with LP coolant from ECW System / station auxiliary cooling  water

system and also from a separate emergency cooling water from over head tank source.  This

supplier cooling water to

i)                LP Cooler for Pump Motor and

ii)              HP fill and Purge cooler.

The boiler circulating pumps are operated through H.T.Motors which are provided with cavity in which

DM Water is filled and this cavity filling is for cooling the motor while the motor is in operation.

continued to part-II