After completion of ESP mechanical erection a major activity starts
before insulation of ESP. ESP insulation takes more than six months
depends on two main factors . One is completion of Air leak test and
other is availability of insulation material and plate type heaters at site.
For a 500MW /660 MW unit with Indian coal at 8000 to 10000
numbers of Scaffolding pipes are required for insulation. Therefore
before proceeding to commissioning of ESP and electrical equipment
we will discuss about the ' AIR LEAK TEST ' of ESP.
Objective
The objective of this test is to prove that the air -in-leakage into ESP is
within the guaranteed value of 1% of design gas flow rate.
An air tightness test ( conversely ,ESP air -in -leakage test) shall be
performed on each pass of the precipitator on completion of erection of
ESP casing, hopper ,inlet/outlet funnels with all internals , inner roof etc.
All welding completed on the casing and all openings are closed. For
closing inlet and outlet funnel we require 6 to 10mm plate to close the
inlet and outlet funnel mouth. Also require number of small plates to
close all the hopper mouth. It will be prudent if outlet ducts are erected
with damper so that one side can be done along with part of outlet duct.
However it is seen that during conductance of Air tightness test BOF to
ESP inlet funnel duct does not get ready therefore it will be wise to go
with the plate.. The test shall be conducted at different pressure conditions
viz. 100mm ,150mm,200, 250mm and 300mm of water column. An
external system comprising of suitable fan, measuring elements and
temporary ducts /pipes and calibrated venturi meter is required to conduct
the test.
Specification of Fan
- Type - HCMB-- 3050
Flow - 20000 m3/hr
Speed - 2640 rpm
Pressure - 7000 pascals
Power required - 46.5 KW
Density - 1.2 kg/cm3 at 20 deg.c
b) Motor - TEFC foot mounted motors
volts - 440volts ,3 phase ,50 hz.
power - 55KW , 2pole
c ) Venturi - calibrated and 03 numbers u -tube manometer to measure
air pressure across the venturi.
Note: This fan is high speed fan and requires temporary foundation at
a suitable location to cater all the passes of the ESP. Without
suitable foundation there will be vibration during the test.
Two dampers will be required inlet and outlet of the fan and out
two one will be regulating and other will be open-close type . Both
the dampers can be manual operated.
Method:
- Keep inlet and outlet damper closed condition start the fan and run it
till it reaches full speed.
- Regulate the inlet damper and slowly pressurise the ESP such a way
that pressure differential remains constant in u tube manometer mounted
on hopper.
-Observe the volume of air being pumped in , for constant pressure differential
by the pressure drop across the venturimeter.
-Repeat the test for differential pressure in ESP viz. 100, 150,200 ,250 and
300 mmwc by varying the damper control of fan and note down
corresponding pressure differentials across the venturi.
- Using the above observations, the air leakage per pass is calculated.
- When stable conditions are established , the mass flow rate of air
through the fan , venturi meter and the precipitator must be constant.
- The mass flow rate of air of the fan is
M(fan) = Q . d
where Q = Volumetric flow of air in m3/hr.
d = Density of air at test condition in kg/m3.
The mass flow rate through the venturi can be written as a function of
the pressure differential and the co-efficient of discharge.
M(venturi) = d1 xK venturi x sq.root of delta P/ d1.
K venturi = Co-efficient of discharge of venturi
d1 = density of air in kg/m3.
delta p = pr. differential across venturi in mm wc.
K(filter ) = Kventuri x sq.root of deltaPventuri/ P(static pressure of air
inside ESP)
The test are conducted for different P ( static pressure) conditions and
K (filter) is calculated. A plot is drawn between K(filter) and P( st.pr)
. From the plot it can be shown that K (filter ) is constant.
continued to next part about commissioning of ESP
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before insulation of ESP. ESP insulation takes more than six months
depends on two main factors . One is completion of Air leak test and
other is availability of insulation material and plate type heaters at site.
For a 500MW /660 MW unit with Indian coal at 8000 to 10000
numbers of Scaffolding pipes are required for insulation. Therefore
before proceeding to commissioning of ESP and electrical equipment
we will discuss about the ' AIR LEAK TEST ' of ESP.
Objective
The objective of this test is to prove that the air -in-leakage into ESP is
within the guaranteed value of 1% of design gas flow rate.
An air tightness test ( conversely ,ESP air -in -leakage test) shall be
performed on each pass of the precipitator on completion of erection of
ESP casing, hopper ,inlet/outlet funnels with all internals , inner roof etc.
All welding completed on the casing and all openings are closed. For
closing inlet and outlet funnel we require 6 to 10mm plate to close the
inlet and outlet funnel mouth. Also require number of small plates to
close all the hopper mouth. It will be prudent if outlet ducts are erected
with damper so that one side can be done along with part of outlet duct.
However it is seen that during conductance of Air tightness test BOF to
ESP inlet funnel duct does not get ready therefore it will be wise to go
with the plate.. The test shall be conducted at different pressure conditions
viz. 100mm ,150mm,200, 250mm and 300mm of water column. An
external system comprising of suitable fan, measuring elements and
temporary ducts /pipes and calibrated venturi meter is required to conduct
the test.
Specification of Fan
- Type - HCMB-- 3050
Flow - 20000 m3/hr
Speed - 2640 rpm
Pressure - 7000 pascals
Power required - 46.5 KW
Density - 1.2 kg/cm3 at 20 deg.c
b) Motor - TEFC foot mounted motors
volts - 440volts ,3 phase ,50 hz.
power - 55KW , 2pole
c ) Venturi - calibrated and 03 numbers u -tube manometer to measure
air pressure across the venturi.
Note: This fan is high speed fan and requires temporary foundation at
a suitable location to cater all the passes of the ESP. Without
suitable foundation there will be vibration during the test.
Two dampers will be required inlet and outlet of the fan and out
two one will be regulating and other will be open-close type . Both
the dampers can be manual operated.
Method:
- Keep inlet and outlet damper closed condition start the fan and run it
till it reaches full speed.
- Regulate the inlet damper and slowly pressurise the ESP such a way
that pressure differential remains constant in u tube manometer mounted
on hopper.
-Observe the volume of air being pumped in , for constant pressure differential
by the pressure drop across the venturimeter.
-Repeat the test for differential pressure in ESP viz. 100, 150,200 ,250 and
300 mmwc by varying the damper control of fan and note down
corresponding pressure differentials across the venturi.
- Using the above observations, the air leakage per pass is calculated.
- When stable conditions are established , the mass flow rate of air
through the fan , venturi meter and the precipitator must be constant.
- The mass flow rate of air of the fan is
M(fan) = Q . d
where Q = Volumetric flow of air in m3/hr.
d = Density of air at test condition in kg/m3.
The mass flow rate through the venturi can be written as a function of
the pressure differential and the co-efficient of discharge.
M(venturi) = d1 xK venturi x sq.root of delta P/ d1.
K venturi = Co-efficient of discharge of venturi
d1 = density of air in kg/m3.
delta p = pr. differential across venturi in mm wc.
K(filter ) = Kventuri x sq.root of deltaPventuri/ P(static pressure of air
inside ESP)
The test are conducted for different P ( static pressure) conditions and
K (filter) is calculated. A plot is drawn between K(filter) and P( st.pr)
. From the plot it can be shown that K (filter ) is constant.
continued to next part about commissioning of ESP
P.S If you are looking to earn few legitimate extra money from the comfort of your home then please click on the link given below
LINK 1 - PLEASE CLICK HERE
LINK 2 - PLEASE CLICK HERE
