Check list for design of APCS (Air Pollution Control System)

1. Check list for design of APCS (Air Pollution Control System) 1. Survey of the problem A. Type of harmful effects on humans B. Properties of the gas C. Gas flow rate D. Particulates ① Liquid or solids ② Size distribution of particles ③ Loading rate(Amount of loading of particulates, mass/volume of gas) ④ Physical/chemical properties E. Location of plant F. Degree of pollution control required G. Excursion of condition

2. Check list for design of APCS (Air Pollution Control System) 2. Solving the Problem A. Process changes B. Alternate materials in process C. Selection of methods of control of emissions D. Existing control system and possible adaptation E. Use of pilot units F. Consideration of other pollution which may occur in consequence 3. Design of system A. Size of equipment B. Space needed for control unit and auxiliary equipments (fans, ducts, disposal, pumps, power supply etc.)

3. Check list for design of APCS (Air Pollution Control System) C. Materials of construction D. Power requirements and pressure drop E. Controls needed(Temperature, Humidity, Flows, other) F. Maintenance needs G. Flexibility of system H. Safety aspects I. Availability of standard equipment or need for special design J. Cost estimate K. Optimizing design L. Alternatives M. Installation permit or variance 4. Performance A. Testing of installed equipment B. Operating permit or variance C. Monitoring regular operation

4. Properties of particle. • The most important properties of an individual particle are size, shape and density. • Other related properties of interest are the surface area, volume and chemical composition of particle. • Concentration • mass concentration : total mass/volume(mg/m3) • number concentration : number/volume(#/m3) • Characteristics of small particle : pp14~15 • fume : 고온에서 입자가 vaporize될 때 발생 용융로에서 다량 발생. 0.001~1 μm • Smog : ambient에서 입경(dp) 1~5 μm 이하의 물질 • Smoke : comburtion에서 입경(dp) 1~5 μm 이하의 물질 • Photo chemical smog : 햇빛에 의하여 형성된 smog

5. Description of individual particles • It reveals that solid particles making up most dusts and fumes are usually very irregular in shape. • Liquid particles present in mists and sprays tend to be spherical. • The irregular shapes observed three general classes. • Isometric : in which all three overall dimensions of the particle are roughly of the same magnitude.(x≅y≅z) • Flat : in which there are much greater lengths in two dimensions than in the third.(x≅y≫z) (e.g. platelets, scales, leaves, etc) • Needlelike : in which there is a much greater length in one dimension than in the other two.(x≫y≅z) (e.g. prisims or fiber)

6. Description of individual particles • It is convenient to try to describe a real irregular particle in terms of the size of simple geometrical shape. • Sphere :diameter = d • Cube :side = d • Cylinder :length =l, diameter = d • Ellipsoid of revolutionpolar radius = p equatorial radius = r • Prolateβ > 1 • β=p/r Oblateβ < 1 • Sphereβ = 1

7. Description of individual particles • The definitions of particle size in common use. • Equivalent diameter : the diameter of a sphere having a volume equal to that of the particle. • Stocks diameter(sedimentation diameter) : the diameter of a sphere of equal density, having the same settling velocity as the particle in a specified fluid. Stocke's law : Cc :Cummingham correction diameter Cc ≈ 1 for dp > 5 μm Cc ≫ 1 for dp < 1 μm

8. Description of individual particles • Aerodynamic diameter : the diameter of a sphere of unit density having the same settling velocity in air as the particle.(환경에서 많이 사용) • unit density(ρp)=1g/cm3 • Projected diameter : the diameter of a circle having the same area as the image of the particle projected parallel to the plane of the microscope view. surface, volume and mass of particle surface area ∝ dp2 volume ∝ dp3 mass ∝ ρp․dp3

9. Description of individual particles Sphericity = < 1

10. 분진의 집진효율 • A : Inlet Concentration • B : Emission Concentration • C : Removal Concentration • 입경(dP)이 클수록 부분집진효율(ηd)도 커진다. • 분진의 형상, 밀도 등의 물리적 성질에 따라 집진효율이 달라진다.

11. n(dP) : dP ~ dP +d(dP)에서의 입자 갯수 N(dP) : 입경 dP까지의 입자 총수

12. Total Mass Total Volume Total Mass Collected overall efficiency based on mass

14. Overall Efficiency for Collectors in series Pt1 Pt2 Pt3 η1 η2 η3 η0 ☜ If η1=η2=η3=••••=ηN

15. Particle size distribution A. Experimental methods are need for determining the mass or number of particles of each size grade in a representative sample of the aerosol. B. The purpose of calculating the total emission : 1) The grade distribution of the coarser particles. 2) bad health effects on humans and animals arise C. Data display : 1) Discrete distribution : Histogram 2) Continuous distribution : x-y graph(Gausian distribution) D. The number or weight values displayed by the raw data may be transformed into (a) fractional or frequency values, or (b) cumulative values.

16. Size Distribution Fution : σ2 : variance , σ : standard deviation

17. 1) Frequency function : fi = ni/Σni ni: number of particles observed in ith interval Σni: total number of particles of all sizes observed fi: fraction of particles of ith interval

18. 2) Cumulative function : Fj = Σfi , Fn = 1 Fj : Fraction of all particles which are smaller than the largest size in the jth interval. call the "cumulative-less-then" fraction ⇒ Log-nomal distribution ln σw = geometric standard deviation ln dw = geometric mean

19. F(lndp) : Cumulation function

20. x, y 축의 변환 x 축 scale의 curve가 직선이 되도록 변화 Log-Probability Curve Probability Curve y 축을 log scale로

23. Terminal velocity (Settling velocity) Force valance ☜ sphere ☜ Stock’s law

24. ☜ Settling Velocity ☜ General