l 23 and 24 final
DESCRIPTION
AIR POLLUTION CONTROL course material by Prof S S JAHAGIRDAR,NKOCET,SOLAPUR for BE (CIVIL ) students of Solapur university. Content will be also useful for SHIVAJI and PUNE university studentsTRANSCRIPT
![Page 1: L 23 and 24 final](https://reader033.vdocument.in/reader033/viewer/2022050920/54be4a1f4a795915468b4604/html5/thumbnails/1.jpg)
L-23Gravity settling chamber
Air Pollution and Control
(Elective-I)
![Page 2: L 23 and 24 final](https://reader033.vdocument.in/reader033/viewer/2022050920/54be4a1f4a795915468b4604/html5/thumbnails/2.jpg)
Gravity settling chamber
• Gravity settling chamber is used toremove large and abrasive particlesgreater than 50 µ from a gas stream.
• This is a simple particulatecollection device using the principle ofgravity to settle the particulate matter in agas stream passing through its longchamber. 2Prof S S Jahagirdar, NKOCET
![Page 3: L 23 and 24 final](https://reader033.vdocument.in/reader033/viewer/2022050920/54be4a1f4a795915468b4604/html5/thumbnails/3.jpg)
• The primary requirement of such a devicewould be a chamber in which the carriergas velocity is reduced so as to allow theparticulate matter to settle out of themoving gas stream under the action ofgravity.
• This particulate matter is then collected atthe bottom of the chamber.
• The chamber is cleaned manually todispose the waste.
3Prof S S Jahagirdar, NKOCET
![Page 4: L 23 and 24 final](https://reader033.vdocument.in/reader033/viewer/2022050920/54be4a1f4a795915468b4604/html5/thumbnails/4.jpg)
4Prof S S Jahagirdar, NKOCET
Gas outlet
![Page 5: L 23 and 24 final](https://reader033.vdocument.in/reader033/viewer/2022050920/54be4a1f4a795915468b4604/html5/thumbnails/5.jpg)
Prof S S Jahagirdar, NKOCET 5
![Page 6: L 23 and 24 final](https://reader033.vdocument.in/reader033/viewer/2022050920/54be4a1f4a795915468b4604/html5/thumbnails/6.jpg)
6Prof S S Jahagirdar, NKOCET
![Page 7: L 23 and 24 final](https://reader033.vdocument.in/reader033/viewer/2022050920/54be4a1f4a795915468b4604/html5/thumbnails/7.jpg)
Gravity settling chamber with trays
7Prof S S Jahagirdar, NKOCET
![Page 8: L 23 and 24 final](https://reader033.vdocument.in/reader033/viewer/2022050920/54be4a1f4a795915468b4604/html5/thumbnails/8.jpg)
• The gas velocities in the settling chamber must be sufficiently low for the particles to settle due to gravitational force.
• Literature indicates that gas velocity less than about 3 m/s is needed to prevent re-entrainment of the settled particles. The gas velocity of less than 0.3 m/s will produce good results.
8Prof S S Jahagirdar, NKOCET
![Page 9: L 23 and 24 final](https://reader033.vdocument.in/reader033/viewer/2022050920/54be4a1f4a795915468b4604/html5/thumbnails/9.jpg)
Design Parameters:-For 100 % efficiency
--------------Eq -i
Where,
H= height of settling chamber
L = Length of settling chamber
Vt = Velocity of settling
VH = velocity of flow Prof S S Jahagirdar, NKOCET 9
t H
H LtV V
![Page 10: L 23 and 24 final](https://reader033.vdocument.in/reader033/viewer/2022050920/54be4a1f4a795915468b4604/html5/thumbnails/10.jpg)
From equation I Settling velocity may be given by
-------------Eq – ii
W= width of chamber
(As Q = area of inlet x velocity = W.H.VH )
For streamline flow settling velocity is given by
------------- Eq- iii
Prof S S Jahagirdar, NKOCET 10
HV H QVt
L LW
2. .
18.
p p
t
g dV
![Page 11: L 23 and 24 final](https://reader033.vdocument.in/reader033/viewer/2022050920/54be4a1f4a795915468b4604/html5/thumbnails/11.jpg)
• Equating equations ii and iii,
therefore, we get,
-------Eq iv
Prof S S Jahagirdar, NKOCET 11
2. .
18.
p pHg dV H
L
min
18. .
. .H
p
p
H Vd
g L
dpminis min size of particle that can be removed
with 100 % efficiency
![Page 12: L 23 and 24 final](https://reader033.vdocument.in/reader033/viewer/2022050920/54be4a1f4a795915468b4604/html5/thumbnails/12.jpg)
Prof S S Jahagirdar, NKOCET 12
min
18. .2
. .H
p
p
H Vd
g L
For better and conservative results multiplying factor 2 can be taken
Efficiency of settling chamber is given by
min
2
p
p
d
p
d
d
![Page 13: L 23 and 24 final](https://reader033.vdocument.in/reader033/viewer/2022050920/54be4a1f4a795915468b4604/html5/thumbnails/13.jpg)
• Another equation for calculation of efficiency is
Prof S S Jahagirdar, NKOCET 13
2. .1 exp
18. . .
p p
H
g d L
V H
![Page 14: L 23 and 24 final](https://reader033.vdocument.in/reader033/viewer/2022050920/54be4a1f4a795915468b4604/html5/thumbnails/14.jpg)
Settling chamber with trays
Prof S S Jahagirdar, NKOCET 14
Settling trays can be used to improve removal efficiency.
![Page 15: L 23 and 24 final](https://reader033.vdocument.in/reader033/viewer/2022050920/54be4a1f4a795915468b4604/html5/thumbnails/15.jpg)
If, n = number of trays, then equation iv becomes
min
18. .
. . .H
p
p
H Vd
n g L
Prof S S Jahagirdar, NKOCET 15
![Page 16: L 23 and 24 final](https://reader033.vdocument.in/reader033/viewer/2022050920/54be4a1f4a795915468b4604/html5/thumbnails/16.jpg)
Advantages1. Low initial cost
2. Simple construction
3. Low maintenance cost
4. Low pressure drop
5. Dry and continuous disposal of collected solids
6. Can be constructed of any material
7. Temperature and pressure limitations are imposed by type of material used
Prof S S Jahagirdar, NKOCET
16
![Page 17: L 23 and 24 final](https://reader033.vdocument.in/reader033/viewer/2022050920/54be4a1f4a795915468b4604/html5/thumbnails/17.jpg)
Disadvantages
1. Large space requirement
2. Only comparatively large particles can be collected
Prof S S Jahagirdar, NKOCET 17
![Page 18: L 23 and 24 final](https://reader033.vdocument.in/reader033/viewer/2022050920/54be4a1f4a795915468b4604/html5/thumbnails/18.jpg)
Applications of settling chamber• Settling chambers are mostly used as
pre-cleaners. They are sometimes used in the process industries, particularly in the food and metallurgical industries as the first step in dust control.
• Use of settling chambers as pre-cleaners can also reduce the maintenance cost of high efficiency control equipment, which is more subject to abrasive deterioration. 18
Prof S S Jahagirdar, NKOCET
![Page 19: L 23 and 24 final](https://reader033.vdocument.in/reader033/viewer/2022050920/54be4a1f4a795915468b4604/html5/thumbnails/19.jpg)
Problem (Peavy -Rowe)
Prof S S Jahagirdar, NKOCET 19
Assume viscosity of air = 2.1 x 10-5 kg/m.s
![Page 20: L 23 and 24 final](https://reader033.vdocument.in/reader033/viewer/2022050920/54be4a1f4a795915468b4604/html5/thumbnails/20.jpg)
Solution :-
Prof S S Jahagirdar, NKOCET 20
![Page 21: L 23 and 24 final](https://reader033.vdocument.in/reader033/viewer/2022050920/54be4a1f4a795915468b4604/html5/thumbnails/21.jpg)
Objective questionsQ1. Gravity settling chamber removes _____________
particles.
Q2. In gravity settling chamber, the gas velocity of less than _______ m/s will produce good results.
Q3. If trays are used in settling chamber efficiency _______________.
Q4. True or false?
1.Settling chamber can be connected with other control equipments in series to increase efficiency.
21Prof S S Jahagirdar, NKOCET
![Page 22: L 23 and 24 final](https://reader033.vdocument.in/reader033/viewer/2022050920/54be4a1f4a795915468b4604/html5/thumbnails/22.jpg)
2. Settling chamber can remove less than 1 µ particles with 90% efficiency.
3. Increase in flow velocity increases efficiency of settling chamber.
Prof S S Jahagirdar, NKOCET 22
![Page 23: L 23 and 24 final](https://reader033.vdocument.in/reader033/viewer/2022050920/54be4a1f4a795915468b4604/html5/thumbnails/23.jpg)
Theory questions
Q1. Explain working of gravity settling chamber with neat sketch. Also give advantages and disadvantages.
Q2. Write a note on ‘Design of gravity settling chamber’.
23Prof S S Jahagirdar, NKOCET