Page 315 - Applied Process Design For Chemical And Petrochemical Plants Volume II

304 Applied Process Design for Chemical and Petrochemical Plants
'1
log - 0.206 log [(E) (-) (z)
Volume flow = 97,300/(24) (3,600) (2.47) = 0.4559 f$/sec
Area required = .4559/0.667 - 0.6835 ft2 (= 98.4 in2) NN = (9 - 38)
Column diameter = 11.19 in. NM D XIF
Use = Win. I.D. column
(-)
10,100 0.45 0.05
log- NN = 0.20610g(-) (-)2
Bottom of Column: NM 13,900 0.55 0.10
= 0.206 log 0.149
= 0.0095 cp
p~ = 0.07 cp = -0.206 (0.837)
= -0.1723
log- NM = 0.1725
NN
pL = 0.4 (62.4) = 25 lb/ft3

L/G = .,/= (107,400/97,300)~~ 0.346
=
=
1.487 (NN) + NN = 40
Using packing factor, F = 56 for 1-in. Pall metal rings
Reading chart: Then: NN = 16.08 ft, rectifying section; use 1 16.5-ft section
NM = 23.92 ft, stripping section; use 2 12-ft sections
-
@ FPO.'/(PG) (p~ PG) (g,) = 0.057, flooding, for reference,
loading reads = 0.036 Allow 2 ft space between support of top section and
redistributor of section 2 (from top).
@ (56) (0.07)0.1/(2.47) (25 - 2.47) (32.2) = @ (0.02394) Estimated pressure drop of loading from Figure 9-21C
= 0.40 in water/ft of packing. For totaI packed height, AP
Area Req'd. = 0.4559/0.4048 = 1.126 ft* 3 162.17 in2 (0.40) (16.5 + 24) = 16.2 in. water total (packing only).
Preliminary evaluation of condenser requirements:
Diameter = 14gin. Use 16-in. diameter, See Appendix A-18 Condense: 97,300 lb/day

It is better to use smaller packing (less than 1 in.) in this L, = 115 Btu/lb
diameter column (l6ii. I.D.), such as 36 in. if recalculated q - 97,300 (115)/24 = 466,229 Btu/hr
above. Packing of W in. or M in. are better in thii sine col-
umn; however the effects of packing factor should be cal- For u,ximute estimate: assume overall heat rransfer
culated if changed from M in. packing. coefficient,
HETP: Use HETP = 18 in. based on on-site column data
and manufacturer's confirmation that for % in. Pall rings U = 100 Btu/hr (ft2) (OF)
in this system, the 18 in. HETP should perform satisfacto-
rily. Note: For each design verify expected HETP through AT = 35°F for (-25°F propylene)
the manufacturer.
Redistribute the liquid every 10 ft and allow 2 ft addi- Area Estimated = 466,229/(100) (35) = 133 ft2 (outside tubes)
tional for redistribution = 36 ft. Then use 4-10 ft sections
of packing. For 20 theoretical plates, total performance Recommend kettle type condenser (boiling propylene)
packed height 20 (18 in./12 in.) = 30 ft. Allow for loss of (see chapter on Heat Transfer, Volume 3).
equilibrium at (1) reflux entrance = 1 HETP and (2) feed
entrance = 2 HETP and (3) redistribution (2) = 2 HETP; Nutter Ring [97]
totals 5 HETP.
Nutter offers an improved high performance random
packing identified as Nutter RingTM, see Figure 9-6K To
5 x 1.5 ft = 7.5 ft extra packing.
achieve the best performance from any random packing,
the liquid distributor must be level and the distributor
Total packing to install = 30 ft + 7.5 ft = 37.5 ft; Use 40 ft. points of the discharging liquid to the packing must be
Feed point, based on Kirkbride (See Chapter 8): uniformly distributed, see earlier discussion on this topic.