02 BOPs / Woods D.R 2008 rules-of-thumb-in-Engineering-practice (epdf.tips)

			Appendix B:	Dimensionless Groups		371
Dimensionless		Word definition	Equation	Range	So what?
number
Power no. =	Po	drag on paddle/	P/(r Di5 N3)	104 to	Agitation: Power for
Newton no.		inertial force		1016	mixing impellers; ro-
					todynamic machinery.
					Power number =
					Newton no. if Fr no.
					not important; that is
					no vortex. For Re i
					104, for turbines Po
					usually = 1–6; for
					marine propellers, Po
					usually = 0.2–1
Prandtl no.	Pr	molecular momen-	cp m/k		Heat transfer: liquid
		tum transfer/mo-			metals: 0.005–0.2
		lecular heat transfer			gases: 0.6–1
					liquids: 0.02–50 000
Prater no.	Pra	relative increase in	(concentration of		Reactions; heat trans-
		temperature of the	reactant at surface)		fer. Pra I 0 for en-
		catalyst pellet = heat	(heat of reaction)		dothermic reactions
		of reaction/thermal	effective diffusivity		and usually in the
		conduction of heat	in the pores)/		range –0.8 to 0; the
		away	effective thermal		efficiency = (rate of
			conductivity of cata-		reaction controlled by
			lyst q surface tem-		diffusion/rate of reac-
			perature		tion without diffusion
			[A] (–DH) D/(kT)		limitation) is always
					I 1. Pra i for exo-
					thermic and usually
					in the range 0 to 0.8.
					efficiency can be i 1,
					= 1 or I 1
Rayleigh no.	Ra	(free convection	[b (dT/dy) g d4 r2 cv]/		Convection
		buoyancy force)/	[k m]		Coating: critical value
= Gr Pr		(thermal diffusivity)	b = coefficient of		when roll cells might
			thermal expansion;		occur is between 320
			d = film thickness		and 1700 to support
			bDT g Dp3 r2 cp/(k m)		density driven roll
					cells

372 Appendix B: Dimensionless Groups

Dimensionless		Word definition	Equation	Range	So what?
number
Reynolds no	Re	inertial forces/	pipe:		Fluid flow in tubes:
		viscous forces			laminar I 2300
= Damkohler V,
DaV
			spinning flows		Coating flows and
			r2 V r/m		size reduction: lami-
			where V = rpm		nar film flow on
					spinning disk if
					Re I 105
			r Ivi b2/L m		Coating flows: Slot of
					height b and length L
			falling film as in	1–100	Coating
			curtain coating
			packed bed
Schmidt no.	Sc	(molecular momen-	m/r D	1–106	Mass transfer: materi-
		tum transfer)/			al property ratio im-
		(molecular mass			portant for predicting
		transfer)			mass transfer rates.
					ideal gas Sc = 1
					usual gas = 0.8
					inorganic gas =
					0.6–1.1
					water = 1200
					organic liquids =
					300–2000
					Combustion
Sherwood no.	Sh	(total mass trans-	kG D/D	2–100	Mass transfer: para-
= Taylor no		fer)/(molecular			meter for the mass
		mass transfer)	kL D/D		transfer coefficient
			where kG [=] L/T
Stanton no.	St	Nu/(Re Pr):	h (or U)/		Forced convection:
		(total heat transfer)/	(r cp Ivi)		flowing system
		(turbulent momen-
		tum transfer)
Stanton no.II	StII	cooling capacity of	(UAt)/	0.01–2	Reactor: batch system
		the system: heat	(r cp V)
		transferred/volume
		of hot stuff
Stanton no. for	StD	mass transfer coef-	kG/Ivi
mass transfer		ficient/inertial
Sh/(Re Sc)			where kG [=] L/T

			Appendix B:	Dimensionless Groups		373
Dimensionless		Word definition	Equation	Range	So what?
number
Stokes		gravitational/vis-	g D2r/m v	0.7–800	Particle dynamics;
		cous			Coating
Taylor no.	Ta		r v (r2–r1)/	i 41.3	Vortices in annulus
			(m [(r2–r1)/r2]0.5)		between rotating
					cylinders
Thring no.	Th	bulk heat transfer/	r cp Ivi/eh T3		Heat transfer
(Boltzman no)		radiation heat
		transfer
Weber	We	inertial force/	rc D v2/g		Bubble and drop
		surface tension	where Dp = drop		formation:
		force: = Re Ca	diameter for drop		G–L or L–L: Dp drop
			breakup		breakup
			Di = impeller dia-		We I 12 vibrational
			meter for breakup		mode
			in stirred tank		12 I We I 50 bag
			rc = density of the		mode
			continuous phase		50 I We I 100 bag-

stamen

100 I We I 350 sheet stripping mode

We i 350 catastrophic

Coating: Drop breakup

Appendix C:

Cox Charts – Vapor Pressures

Rules of Thumb in Engineering Practice. Donald R. Woods

Copyright c 2007 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim ISBN: 978-3-527-31220-7

Appendix C: Cox Charts – Vapor Pressures 375

Appendix D:

Capital Cost Guidelines

Costs should be included with any rules of thumb because costs are such vital information to engineering practice. Therefore, in this book, cost correlations for the FOB cost and factors for estimation of the complete installation of that equipment into a working process are given for each type of equipment. The cost estimates are ball park ideas e 30 %. Here we discuss the correlations, the L+M* factors to convert FOB costs into bare module costs, factors to obtain the fixed capital investment costs and finally the capital cost guidelines for the equipment described in the main text, with title captions that are the same as in the main text.

D.1

Equipment Cost Correlations

Costs are usually correlated in terms of a base cost multiplied by a ratio of sizes

raised to the power “n”. Cost2 = Costref (size2/sizeref )n. The cost is usually the FOB cost although sometimes it is the field erected cost. The size should be a “cost

dependent” parameter that is characteristic of the specific type of equipment. The size parameter that provides the least accurate estimate is the flow or capacity. In this book, sometimes several different parameters are given; use the size parameter flow or capacity as a last resort.

The guideline FOB cost is in US $ for a value of the Chemical Engineering Index (1957–59 = 100), CEPCI Index = 1000. The value of the CEPCI Index for the year 2003 was 395.6 so that the costs reported here are more than double the value in 2003.

D.2

Converting the FOB Cost into a Bare Module Cost

Although the FOB cost of equipment is of interest, usually we want to know the cost of a fully installed and functioning unit. The “bare module”, BM, method is used in this book. In the BM method, the FOB cost is multiplied by factors that account for all the concrete, piping, electrical, insulation, painting, supports needed in a space about 1 m out from the sides of the equipment. This whole

Rules of Thumb in Engineering Practice. Donald R. Woods

Copyright c 2007 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim

ISBN: 978-3-527-31220-7

D.2 Converting the FOB Cost into a Bare Module Cost 377

space is called a module. The module is sized so that by putting together a series of cost modules for the equipment in the process we will account for all the costs required to make the process work. For each module we define a factor, L+M*, that represents the labor and material costs for all the ancillary materials. Some of these may be shown as a range, for example, 2.3–3. This means that for the installation of a single piece of equipment (say, one pump), the higher value should be used; the lower value is used when there are many pumps installed in the particular process. The L+M* factor includes the free-on-board the supplier, FOB, cost for carbon steel and excludes taxes, freight, delivery, duties and instruments unless instruments are part of the package. The * is added to remind us that the instrumentation material and labor costs have been excluded, (whereas most L+M values published in the 60s, 70s and 80s included the instrumentation material and labor costs).

If the FOB cost is for non-carbon steel equipment, then the L+M* factor must be reduced (since the factor is to account for concrete, electrical, insulation, painting – items that are independent of the materials of construction of the equipment). Two ways to handle this are: (i)Reduce the L+M* factor, for s/s typically reduce by multiplying by 0.6 to 0.75. The corrections are given in Fig. D.1 (ii) Cost an imaginary carbon steel piece of equipment, multiply by the L+M* factor and then add the difference in FOB cost between the alloy equipment and the carbon steel equipment.

For some unit operations the equipment is built of concrete or is a lagoon. For such equipment the reported cost is the physical module, PM cost, that represents the FOB plus L+M* plus instruments plus taxes and duties. The cost excludes offsite, home office expense, field expense and contractor’s fees and contingencies. Rules of thumb to account for the other cost items are given in Section 1.7. The pertinent sections of Section 1.7 are reproduced below.

Figure D.1 Correction factors for L+M* as a function of alloy factor.

378Appendix D: Capital Cost Guidelines

D.3

Converting FOB and L+M Costs into Total Fixed Capital Investment Costs

The rules of thumb refer to capital cost estimation.

1.Total fixed capital cost estimation, total fixed capital investment = 3 to 10 (4 to 5 usual) q FOB major pieces of equipment. The factor decreases as more alloys are used in the process.

2.For capital cost estimation: for carbon steel fabrication: L+M factors are in the range 1.5 to 3 with corresponding L/M ratios of 0.15 to 0.65 with 0.4 being usual. The factor decreases for alloys as shown in Fig. D.1.

3.For capital cost estimation: FOB equipment cost increases with sizen where n is usually 0.6 to 0.7. When n = 1 there is no capital cost advantage to building larger; increase size or capacity by duplicating equipment.

4.For capital cost estimates:

(FOB q L+M* ) + installed instruments + buildings required within the battery limits = L+M cost.

L+M cost + taxes, freight and insurance at 15–25 % FOB cost = physical module cost, PM.

PM + offsites + indirects for home office and field expenses at 10–45 % of L+M with small values for large projects = bare module or BM cost.

BM cost + contractors fees (3–5 % BM) + contingency for unexpected delays (10–15 % BM) + design contingency for changes in scope during construction (10–30 % BM) = Fixed capital investment or total module, TM, cost.

To the fixed capital investment might be added, as needed:

1.royalties and licenses.

2.land ( 1–2 % TM).

3.spare parts (1–2 % TM).

4.legal fees (1 % TM).

5.working capital: for year-round commodities (15–20 % TM); for seasonal commodities (25–40 % TM). For specialties and pharmaceuticals (15–40 % of sales).

6.startup expenses (15–40 % TM).

D.4

Detailed Equipment Cost Data Based on Equipment Type

Here are the details of the cost correlations for the equipment discussed in the text. The subheading captions correspond directly with the titles in the text. All costs are FOB costs (unless stated otherwise). All costs are for the basis CEPCI = 1000.

D.4 Detailed Equipment Cost Data Based on Equipment Type 379

Section 1.4

Rules of Thumb about the Context for a Chemical Process: Process Control Sensors

Pressure: FOB $4000. L+M* = 1.65. L/M = 0.09. Temperature: FOB $6000. L+M* = 1.2. L/M = 0.09.

Flow: sensor, barrier and transmitter: coriolis: FOB $10 000; magnetic: 304 s/s with teflon lining. FOB cost = $11 000 for a pipe diameter = 15 cm with n = 0.26 for the range 1–15 and n = 1.67 for the range 15–25 cm. L+M* = 1.65. L/M = 0.09.

Level: electronic d/p cell: FOB $5000. L+M* = 1.1.

Level: visible flat-glass, s/s. FOB cost = $900 for a visible length = 75 cm with n = 0.9 for the range 20–200 cm. Alloy factor, s/s, q 1.00; c/s, q 0.8. L+M = 1.1.

Alarms:

Level alarm: FOB $1000. L+M* = 1.65. L/M = 0.09.

SIS:

Hi-lo level shutoff: FOB $5500. L+M* = 1.65. L/M = 0.09

Control valves:

Control valve: Fail open or fail close, cast steel, pneumatic diaphragm actuated, quick opening, V-pup or throttle plg, 316 s/s trim excluding valve positioner. FOB cost = $4800 for a valve diameter = 7.5 cm with n = 0.65 for the range 2.5–7.5 and n = 1.53 for the range 7.5–23 cm. FOB cost = $28 000 for a valve diameter = 23 cm with n = 3.0 for the range 23–30 cm. L+M = 1.10. L/M = 0.03. Alloy factors: cast steel, q 1.0; cast iron, q 0.63.

Control valves including all materials: cost $240 000 for the number of main plant items, MPI, = 75 with n = 1.2 for the range 15–400. Alloy cost factor: c/s q 1.00; chrome/moly q 2.4; s/s q 4.2.

Butterfly valve: c/s, piston. FOB cost = $6500 for a valve diameter = 28 cm with n = 0.28 for the range 5–28 and n = 1.28 for the range 28–40 cm.

Relief valves:

Spring loaded, Crosby style JO, type A, c/s body and spring. Maximum temperature 230 hC. FOB cost = $3800 for an inlet valve diameter = 5.5 cm with n = 0.75 for the range 2.5–5.5 and n = 1.00 for the range 5.5–15 cm. FOB cost = $10 000 for an inlet valve diameter = 15 cm with n = 2.1 for the range 15–20 cm. L+M* = 1.13. L/M = 0.1.

“Control systems”: In the past, the cost of the control system for different process equipment was often estimated as a percentage of the FOB cost of the equipment and thus was included in the so-called L+M factor. More recently, and in this book, we use the L+M* factors that exclude an allowance for the cost of the instrumentation and control system. The instruments and control system should be costed separately. The installed instrumentation costs, excluding control valves,

are (US	dollars, CEPCI	= 1000): for gas phase reactors, $63 000; for	liquid
phase reactors $70 500;		for condensers, $40 000; heat exchanger or reboilers,
$27 000;	for distillation	columns, $150 000; evaporators, $25 000; for	storage

tanks, $7000; pressure tank, $8300; intermediate process tank, $17 400; pump or a stage of a centrifugal compressor, $7000.

380Appendix D: Capital Cost Guidelines

x Example use: Estimate the cost, at CEPCI = 800 for the installation of a conventional AVS centrifugal pump whose FOB cost (at CEPCI = 1,000) is $20 000. From Section 2.3 the pump L+M* = 2.3–3; select 3 since this is a one-off installation. Therefore the L+M* module cost for the pump is $20 000 q 3 = $60 000. The cost of the installed instrumentation, from above, is $7000 for a total of $67 000 = L+M cost. To the L+M cost is added the taxes, freight and insurance at 15–25 % of FOB cost to yield the physical module cost, PM cost = $67 000 + 18 % q $20 000 ($3600) = $70 600. Neglecting offsites and building costs, to obtain the bare module, BM, cost add indirects for home office and field expenses at 20–45 % L+M with small values for large projects (or for this case) 0.4 q $67 000 = $93 800 + $3600 = $97 400 = BM cost.

The fixed capital investment = BM cost plus contractor’s fee (3–5 % BM, select 5) plus contingency (10–15 % BM, select 15) plus design contingency for changes in scope during the project (10–30 % BM, select 10) to give a total = $126 620 at CEPCI = 1000.

At CEPCI = 800 an estimate of the fixed capital cost =$126 620 q 800/1000 = $100 000 e 20 %.

Section 2.1

Gas Moving: Pressure Service

Fans, centrifugal, radial bladed, 2.5 kPa g, excluding motor, starter, gearing. FOB cost = $15 850 at inlet gas flow rate = 10 Nm3/s with n = 0.78 for the range 2–100. L+M* = 1.4–1.7. L/M = 0.25. Alloy factors: c/s, q 1.00; fiberglass, q1.8; s/s, q 2.5. Factors: radial bladed, q 1.00; backward bladed, q 1.20.

Fans, centrifugal, radial bladed, 2.5 kPa-g, TEFC motor, starter and gearing. FOB cost = $27,750 at inlet gas flow rate = 10 Nm3/s with n = 0.93 for the range 2–50. L+M* = 1.4–1.7. L/M = 0.25.

Fans, vane-axial, 0.5 kPa g, open drip proof motor. FOB cost = $5000 at inlet gas flow rate = 1 Nm3/s with n = 0.36 for the range 0.5–10. L+M* = 1.4–1.7. L/M = 0.25.

Fans, propeller, including motor and housing. FOB cost = $4000 at inlet gas flow rate = 7 Nm3/s with n = 0.58 for the range 0.5–7 and n = 0.36 for the range 7–50. L+M* = 1.4–1.7. L/M = 0.25.

Fan unit, air conditioning package with two fans, chiller, integral piping, heat exchangers, filter excluding ductwork, refrigeration and cooling tower circuits, overheads and building. L+M cost = $48 000 at inlet gas flow rate = 3 Nm3/s with n = 0.67 for the range 0.8–8.

Fan unit, air conditioning package with two fans, chiller, integral piping, heat exchangers, filter excluding ductwork, refrigeration and cooling tower circuits, overheads and building. FOB cost = $490 000 at inlet gas flow rate = 30 Nm3/s with n