In this presentation i have made the design and development of De-Dusting system for the reduction of dust and chemical emission from the atmosphere of the steel industry (Electrotherm India Ltd.) [Final Semester project Mechanical Engineering 8th sem]
2. Content
Literature review
Identification of problem
Emission of dust and chemicals
What is De-dusting system
Calculations
Fan Efficiency
RMHS System
Checking of the ID fan capacity
4. Literature review
Development in the dust reduction technique have been done by many
engineers and how to reduce the dust from the plant is continuously
improving.
At first the dust from the foundries and the steel industries were removed
or minimized with the help of the exhaust fan or blower or huge fans.
And with this the development of the bag filter dust collection carried out,
with day by day increasing the demand for higher efficient dust removal.
5. Literature review
This system works on the basis of bag filter dust collection, where the
induced draft fan Is used for the suction of the dust from various dust
generating points.
The different points are provided for the suction of dust and the
header and the suction pipe from the main point is connected to the
header and thus that dust than goes to the bag filter dust collection
chamber.
Now when the dust and the fine particles are there in the chamber then
there are different filter bags provided in which the long cage around
2500 mm length is there.
6. Literature review
The cage is provided with the fiber cloth mostly
used material is P.T.F.E (polytetrafluoroethylene)
whose resisting temperature is 326.8 °C.
Now when dust enters the chamber then it goes to
the filter bag and sticks there.
below these bags the hoper section is there and
beneath the hopper there is valve which discharges
the dust and the other particles.
7. What is De-Dusting System.
The De-dusting system works on the basis of the induced draught
fan.
The ID fan is connected with the ducting system.
The ducting system/header is generally 250-300 mm diameter
pipe and that is connected through the different suction points.
The different suction points are the one which are situated over
the different discharge points over there the raw material is
discharged.
Further the ID fan outlet is connected through the chimney for
the exhaust of gases to the atmosphere.
8. Identification of problem
The process discussed above is for BF2 and the same process is for BF1 but
the RMHS system is open to atmosphere for BF1.
In BF1 the material from ground is discharged to the RMHS building which is
at 4th floor (12.58m) height.
The raw material is discharge at top floor through belt conveyor.
The building consist of 4 big hopper and these hopper consists of different
raw material according to the requirement of every day.
The hopper generally 2 hopper of COKE and other two are iron ore.
9. Identification of problem
The material is discharged at the top floor and that contains the shuttle
trolley.
The trolley is moved according to material onto which it is to be
discharged.
At the time of discharge the dust which is generated from the material
when it falls is very high and the visibility is zero at this time.
And due to this the discharge is done at morning, then at noon, and at
night.
10. Emission of dust and chemicals
Picture of RMHS Dust and Chemical emission while
charging the material in Hopper
11. Identification of problem
And when the hopper is fully filled then it is further discharge through
the vibro-feeder which is at 2nd floor and due to vibration the dust and
chemical emission is very high and technician can not stand near
there.
Beneath the vibro-feeder there is screen which separates the undersize
and oversize material and the required size material to the bottom
conveyor which is ground floor.
And the fines are generated so that is discharged to the fines centre
which is done through conveyor (the dust from the fines is also high).
13. Identification of problem
Now as discussed earlier the two hopper are for Coke.
And the coke is preheated for this the section is made in the coke hopper
section and the hot air at temperature of 250 degree Celsius.
And which is running 24 hrs due to this the dust and fines of coke are
generated very high and the temperature is very high at this time.
So this is the problem which is required to minimized or controlled.
After discussing this problem with concerned guide in industry we have
decided to develop the De-dusting system for the raw material handling
system for BF-1 plant.
14. Different Components of De-Dusting
System
1. Bag Filter
2. Header (Pipe)
3. Chamber containing Bag Filter
4. Chimney
5. Centrifugal fan/ Induced Draft Fan
6. Butterfly valve
15. The working principle of bag filter
Dust contained gas will enter into the upper side path hopper.
In the screen board action of air flow up, reduce the flow
velocity the part of the big particle inertia force due to the role
of dust be separated into hopper.
Dust contained gas enters into the bag filter in the filtration
purification, dust sticks in the outer surface of the filter bag.
As the filter bag dust surface increases and filter import and
export with differential pressure rise.
16. The working principle of bag filter
As the filter bag dust surface increases and filter
import and export with differential pressure rise.
Pulse is a key components of pulse bag filter. Its
service life is the user of the concerns of problems.
18. Calculations.
The darcy-weisbach equation is used for calculating the pressure loss in a
cylindrical pipe of uniform diameter D,
ΔP =Pressure Drop.
F =Pipe friction Co-efficient.
L =Length of pipe
V =Mean Velocity.
D =Pipe Diameter.
ΔP= flV2 /2gd.
19. Calculations.
f =2.738
L =20.650 m
V = 30 m/s (taken by organization)
D =0.3 m
ΔP = 8645.214 Pa
ΔP = 0.0864 bar
ΔP = 2.738 x 20.650 x (30)2 /2 x 9.81 x 0.3
20. Calculations.
Now, the capacity of ID fan which is there in the Electrotherm is 20,000 Nm3/hr
The fan power requirement is to be calculated
P = dp x q
Now,
P = 0.5 x 10 5 x 5.555
P = 277,777.77 (W)
P = 277.77 (kW)
Where
Pi = power consumption (W)
Dp = total pressure loss (Pa)
Q = air volume flow (m3/s)
21. Calculations.
The motor HP required is obtained from the manual of the supplier
[Rajdeep Engineering] is 40HP motor.
22. Fan Efficiency
μf = dp x q / P
μf = 0.958 or 95.8 % efficiency.
Where,
μf = fan efficiency (0-1)
Dp = pressure (Pa)
Q = air volume delivered by fan (m3/s)
P = power used by the fan (W)
μf = 0.5 x 105 x 5.55/ 277.77 x 103
24. Checking of the ID fan capacity.
There are in all 11 suction points from where the air and dust is to be
sucked and they are not operating at the same time.
Thus, the calculation is based on that, the simultaneous operation is 4
suction points at the same time.
The suction points are as follows. Two at the top of the storage
building from where the charging is done i.e. above the shuttle
conveyor trolley there will be 2 suction points. Below the trolley there
are 4 bunkers among them 2 bunkers are of coke and the other 2
bunker are of iron ore.
25. Checking of the ID fan capacity.
From the shuttle trolley the material is discharged in the
bunker and during this the dust emission is very high and so 4
suction points above the bunkers (these all are at 4th floor of
the building i.e. at 11m from the ground).
Then below that there is screen and vibrofeeder are installed
in this area the required size is sent to the conveyor no 3 and
the rest are sent to the fines conveyor which are under size
26. Checking of the ID fan capacity.
The vibro-feeder and the screen section is located at the 4.30m from the ground
and here also the dust emission is very high as the vibro-feeder shakes and
separates oversize and undersize material therefore the dust emission is very high
therefore here also 4 suction points are required to be given.
Below that there is belt conveyor in which the material is discharged and that
material goes to the belt no 4 this material is sent to the Blast furnace-1 and is
discharged at the top of the furnace.
And when the material is discharge in the B.C-4 then there is also emission of dust
thus there also the suction point is to be give therefore in all total 11 suction
points are provided.
27. Checking of the ID fan capacity.
(velocity is assumed to be 25 m/s)
Area= 3.14 x (0.3)2/4 (m)
Area= 0.07065 m2
Now,
Q= Area x velocity
Q= 0.07065 x 25
Q= 1.766 m3/s
And the calculated Q= 6358.5 m3/hr.
28. Checking of the ID fan capacity.
Area= 0.8 x 1
Area= 0.8 m2
And calculated Q= 2880 m3/hr.
29. Checking of the ID fan capacity.
Therefore, the total simultaneous suction points are (Volume flow rate)
Q= 6358.5
+ 2880
+ 6358.5
+ 2880
Thus the required ID fan capacity i.e. 20,000 Nm3/hr. is justified.
Total = 18,477 Nm3/hr.
35. Summary and future work
Timeline Of work
STARTDATE END DATE DESCRIPTION
1-4-17 1-15-17
Industry Visit/ Working
process
11
1-16-17 1-31-17 Project title finalise 15
2-1-17 2-15-17 Literature Review 14
2-16-17 2-28-17 Analyzed the Process 12
3-1-17 3-15-17 Developm ent of De-dusting 14
3-16-17 3-31-17
Design and analysis of the
system
15
4-1-17 4-15-17 Bill of Material 14
4-16-17 4-30-17
Sanction of BOM/ Thesis
w rititng
14
5-1-17 5-15-17 Final subm ission 14
DURATION
(days)
Design of De-dusting System
36. Summary of work
After the first review the calculations and the required
consideration for the De-dusting system have understood
and concerned with the Internal guide about the things to
consider for this system.
Then the calculation of pressure drop and required fan
capacity were carried out.
After doing the calculation then according to the values
the design consideration the layout of De-dusting System
is made.
37. Future Work
The organization Electrotherm Steel and Engineering
India Ltd. have given assurance that they have
accepted the design which I have made after
considering various parameters and based on that
design they are finding the supplier and the company
who can fabricate this De-Dusting System.
38. Future Work
The company have finalized the design and when I
visited to the company the Mechanical Department
of the Blast Furnace plant were deciding when to
start the work on De-Dusting System for Blast
Furnace-1 for Raw Material Handling System. The I.D
fan Capacity is finalized and how much dust will be
there in the air after this implementation of this
system that work is in progress.