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

6.30 STR: Fluidized Bed (Backmix) 271

vanadium]*/[loss of catalyst activity]*/feed concentration high in hydrogen/loss of antimony solution addition. “Increase in the production of light ends”: for FCCU

[ feed contaminated with metals]*/feed concentration high in light ends.

“Erratic or cycling instrument records on holdup, density and the overflow well”: [surging of the catalyst bed]*. “Opaque flue gas from the regenerator”: [poor separation in cyclone in regenerator]/fluidization velocity too high/increase in volume of product through unexpected side reactions/change in feed flowrate/flowrate instrument error. “Vibration in the preheat system”: [ feed contaminated with water]*. “Dp increase between reactor and fractionator inlet”: [coking in overhead lines]*. “Dp lower on the regenerator slide valve”: [poisoned catalyst]*. “Dp between cracker and regenerator incorrect”: fault with the input air blower/fault with the flue gas slide valve on the regenerator/fault with the regenerated catalyst slide valve/fault with the spent catalyst slide valve/fault with the wet gas compressor/fault downstream of the wet gas compressor, such as plugged fractionator overhead condensers (with ammonium chloride salts)/changes in environment air conditions. Regenerator should be about 20 kPa higher than the cracker for Dp across the regenerated catalyst slide valve. “Dp between cracker and regenerator fluctuating”: fluctuating temperature in cracker/fluctuating pressure in regenerator/fluctuating catalyst circulation rate/fluctuating level in the overflow well/shift in catalyst between cracker and regenerator/incorrect aeration of U-bend/incor- rect aeration of standpipe/sticky stack slide valves/sensor control performance for stack slide valve unsatisfactory/moisture in aeration medium/unsteady control of air/U-bend vibration. “Dp across cylcone i expected”: steam flowrate i expected/ air flowrate i expected. “Pressure fluctuating in regenerator”: incorrect aeration of U-bend/incorrect aeration of standpipe/sticky stack slide valves/sensor control performance for stack slide valve unsatisfactory. “Plugged pump on the bottoms of the fractionator”: [poor separation in cyclone]*/velocity through reactor too high/ faulty cyclone design. “Overflow well level low”: [eroded grid holes]*. “Overflow well level high”: [plugged grid holes]*. “Overflow well level fluctuating”: incorrect aeration of U-bend/incorrect aeration of standpipe/sticky stack slide valves/sensor control performance for stack slide valve unsatisfactory/hole in the overflow well.

“Catalyst loss from the regenerator increased”: [plugged grid holes]*/[eroded grid holes]*/foreign debris entering with fresh catalyst/faulty grid design/[poor separation in cyclone]*/steam flowrate i design/air flowrate i design. “Catalyst circulation fluctuates”: [Dp between cracker and regenerator fluctuating]*/fluctuating temperature in cracker/fluctuating temperature in regenerator/fluctuating level in the overflow well/shift in catalyst between cracker and regenerator/incorrect aeration of U-bend/incorrect aeration of standpipe/sensor control performance for air system unsatisfactory/moisture in aeration medium/unsteady control of air/U-bend vibration/coarse particles/hole in the overflow well/sticky stack slide valves/sensor control performance for stack slide valve unsatisfactory/[surging of the catalyst bed]*. “Catalyst becomes lighter in regenerator gradually”: [afterburn in regenerator]*. “Catalyst in fractionator bottoms”: [poor separation in cyclone]*/ velocity through reactor too high/faulty cyclone design. “Catalyst has salt and pepper appearance after regeneration”: air grid deficiency/[ failure of internal seals

272 6 Reactors

in regenerator]*. “Reduced rates of spent catalyst withdrawal”: [poor separation in cyclone in regenerator]*.

“Temperature difference between bed and cyclone inlet in regenerator”: [ failure of internal seals in regenerator]*/[afterburn in regenerator]* and [inadequate regeneration]*. “Temperatures of bed and cyclone are uneven in the regenerator”: hole in the overflow well/[plugged grid holes]*/foreign debris entering with the fresh catalyst/faulty grid design. “Temperature on regenerator shell or U-bend high”: damaged refractory. “Temperature increase in the dilute phase relative to the dense phase”: [afterburn in regenerator]*. “Temperature of the regenerator cannot be lowered”: [low catalyst circulation rate]*. “Temperatures of regenerator too hot i 750 hC ”: excessive heat release.

“Temperature in dilute phase decreases relative to temperature of the dense bed in the regenerator”: [regenerator doesn’t remove all carbon from the catalyst]*. “Feed preheat requirements i usual”: [low catalyst circulation rate]*. “Unexplained increase in coke”: [poor catalyst stripping]*. “High bottom sediment and water levels in the slurry oil product”: [ poor separation in cyclone in the cracker]*. “Higher H/C ratio”: [poor catalyst stripping]*. “Excess oxygen in regenerator high”: [afterburn in regenerator]*/[plugged grid holes]*/[eroded grid holes]*/faulty grid design. “Ratio of carbon dioxide to carbon monoxide is higher than usual”: [afterburn in regenerator]*. “Uneven oxygen distribution in the dilute phase”: [ failure of internal seals in regenerator]*. “Unsteady heat balance”: [surging of the catalyst bed]*. “Stripping steam flowrate i expected”: flowmeter error/steam traps faulty/partially opened valves/ missing restrictive orifice. “Air flowrate i expected”: flowmeter error/partially opened valves/missing restrictive orifice. “Flow reversal with feed going incorrectly to the regenerator”: [Dp across the regenerator slide valve is I design]*.

[Afterburn in regenerator]*: for FCCU [ failure of internal seals in regenerator]*/too much excess air/oxygen recorder reading incorrect/meter error for feed and recycle flowmeters/meter error for cyclone flowmeter/[insufficient carbon production on catalyst during cracking]*/air flowrate to regenerator too high/[plugged grid holes]*/[eroded grid holes]*/faulty grid design causing localized air distribution problem.

[Coking in overhead lines]*: insulation missing or damaged on transfer line/ extremely cold/increase in heavies and condensibles in reactor products. [Control air flowrate too low]*: controller for air faulty or poorly tuned.

[Failure in regenerator plenum]*: faulty cyclone design/catalyst feed too high/regenerator velocity too high/faulty spray nozzles causing impingement of plenum sprays/temperatures too high causing failure in plenum.

[Feed contaminated with metals]*: abnormal operation in the upstream atmospheric and vacuum units.

[Feed contaminated with heavy hydrocarbons]*: leak in heat exchangers/partly open valves. [Feed contaminated with light hydrocarbons]*: leak in heat exchangers/partly open valves.

[Feed contaminated with sodium]*: seawater leak in upstream equipment/treated boiler feedwater leaks into feed/upset in upstream caustic unit.

6.31 TR: Tank Reactor 273

[Feed contaminated with water]*: water in feed tanks/leaks from steam-out connections/steam leaks in tank heaters/water not cleaned out of the lines at startup/ moist air not removed from lines at startup.

[Higher reactor velocities]*: [ feed contaminated with metals]*.

[Higher regenerator holdup]*: hole in the overflow well.

[Increased air requirements in regenerator for the same conversion in the cracker]*: [ feed contaminated with heavy hydrocarbons]*/[inadequate regeneration]*/[coke on catalyst i usual].

[Insufficient coke production on catalyst during cracking]*: cracking operation intensity is lower than usual/higher quality of feed to the cracker than usual for FCCU fewer aromatics in feed.

[Low catalyst circulation rate]*: partial blockage of the U-bends/excessive stripping steam/insufficient aeration/[control air flowrate too low]*/differential pressure between cracker and regenerator set incorrectly or fluctuating.

[Poor catalyst stripping]*: insufficient steam stripping flowrate/faulty flow controller on steam flow/faulty design of stripper/reactor temperature too low/faulty contacting between steam and catalyst/circulation rate too high/coarse particles.

[Dp across the regenerator slide valve is I design]*/sudden drop in regenerator pressure/regenerator slide valve sticking partly open/compressor surge (see Section 3.1).

[Regenerator doesn’t remove all carbon from the catalyst]*: [excessive coke formed in cracker]*/low excess oxygen/oxygen sensor error/flowmeter error for air/[poor air distribution]*/flowmeter error for feed and recycle/air flowrate too small.

[Sodium on catalyst]*: carryover of sodium from upstream units (caustic)/treated boiler feedwater used in regenerator sprays/[ feed contaminated with sodium]*.

[Uneven oxygen distribution in the regenerator]*: hole in the overflow well/[plugged grid holes]*/foreign debris entering with fresh catalyst/faulty grid design. [Unstable catalyst bed]*: airflow too low/grid holes eroded/faulty grid design.

For calciner

“Excessive temperature rise in the freeboard”: faulty solids introduction into calciner.

“Increased scale”: faulty solids introduction into calciner.

6.31

TR: Tank Reactor

Minimum to no internal mixing. Could have external circulation.

x Area of Application

Phases: Gas–liquid–biosolid; liquid–biosolid.

Gas: use tank with external circulation for homogeneous, exothermic reactions with slow reaction rates.

274 6 Reactors

Liquid plus biosolid:

Anaerobic digesters: (conventional first stage): batch microbiological treatment of municipal sludge; no mixing: use for I 50 m3/s. For high strength waste water with COD i 4000 mg COD/L.

Anaerobic ponds: not common.

Facultative lagoons and ponds: use when the price of land is inconsequential. Low flows with COD about 500 mg COD/L and TSS about 500 mg TSS/L.

Aerobic ponds: use when the price of land is inconsequential. Low flows with COD about 500 mg COD/L and TSS about 500 mg TSS/L.

x Guidelines

Liquid plus biosolid:

Anaerobic digesters: (conventional first stage):Residence time 30–60 d (35 hC); organic loading = 4–9 mg VS/s m3; Circular, diameter 6–35 m; depth = 6–14 m. Anaerobic pond: residence time: 5 d; surface loading 600–3500 mg BOD5/s m2 with 150 mg BOD5/s m2 for winter conditions; volumetric loading 3–100 kg BOD5/s m3. pH 6.7–7.1; depth 1–2.5 m.

Facultative lagoon with surface aeration: residence time = 7–20 d, usually 4–8 d, and longer in cold temperatures; loading 40–130 mg BOD5/s m2; depth 2.4–4.8 m; surface aeration power to oxygenate.

Facultative pond: residence time: 7–50 d; surface loading 43–100 mg BOD5/s m2; (50–120 kg BOD5/half day), depth 1–2.5 m; length/width = 3/1. No surface aeration; photosynthesis is source of oxygen; recycle ratio = 0.2–8, usually 4–8.

Aerobic pond: residence time: 2–6 d; surface loading 43–100 mg BOD5/s m2; (50–120 kg BOD5/half day), depth 0.15–0.45 m; recirculation ratio = 0.2–2. 12 kW/m3 Related topic aerobic lagoon, see Section 6.26.

6.32

Mix of CSTR, PFTR with Recycle

x Application

Phases: Gas–liquid and biosolid. Biosolid removes the soluble organics, COD or BOD5, from waste water. Variety of reactor configurations. Related topics: trickling filter, Section 6.16, CSTR, Section 6.29, CSTR in series, Section 6.26. Slow reactions.

Conventional PFTR activated sludge: average strength domestic waste water with 500 mg COD/L, susceptible to shock loads, 85–95 % removal.

Conventional Backmix activated sludge: usual strength domestic waste water, resistant to shock loads, 85–95 % removal.

Step aeration, modified aeration PFTR activated sludge: higher strength domestic waste water, 85–95 % removal.

Contact stabilization: PFTR: OK for domestic waste water; unsuitable for most industrial waste water, flexible, 80–90 % removal.

6.32 Mix of CSTR, PFTR with Recycle 275

Extended aeration Backmix activated sludge (oxidation ditch): average to low organic loadings (300–500 mg COD/L), small capacity I 40 L/s; flexible, 75–95 % removal.

High rate aeration Backmix activated sludge: high strength domestic waste water, 75–90 % removal.

x Guidelines

Conventional PFTR activated sludge: mean cell residence time = 5–15 d; food/ microorganism ratio = 2.3–4.6 mg BOD5/s kg MLVSS; volumetric loading = 0.3–0.6 kg BOD5/m3; MLSS = 1.5–3 g/L; residence time = 4–8 h or 4–12 h for nitrification; recycle ratio = 0.25–0.5. Air requirements = 100 m3/kg of input BOD5.

Conventional Backmix activated sludge: mean cell residence time = 5–15 d; food/ microorganism ratio = 2.3–7 mg BOD5/s kg MLVSS; volumetric loading = 0.8–2 kg BOD5/m3; MLSS = 3–6 g/L; residence time = 3–5 h or 4–12 h for nitrification; recycle ratio = 0.25–1. Air requirements = 100 m3/kg of input BOD5.

Step aeration, modified aeration PFTR activated sludge: mean cell residence time = 5–15 d; food/microorganism ratio = 2.3–4.6 mg BOD5/s kg MLVSS; volumetric loading = 0.6–1 kg BOD5/m3; MLSS = 2–3.5 g/L; residence time = 3–5 h; recycle ratio = 0.25–0.75. Air requirements = 100 m3/kg of input BOD5.

Contact stabilization: PFTR with recycle: mean cell residence time = 5–15 d; food/ microorganism ratio = 2.3–7 mg BOD5/s kg MLVSS; volumetric loading = 1–1.2 kg BOD5/m3; MLSS = 4–10 g/L; residence time = 4–10 h; recycle ratio = 0.25–1. Air requirements = 100 m3/kg of input BOD5.

Extended aeration activated sludge Backmix with recycle: mean cell residence time = 25–30 days; food/microorganism ratio = 0.6–1.8 mg BOD5/s kg MLVSS; volumetric loading = 0.16–0.4 kg BOD5/m3; MLSS = 3–6 g/L; residence time = 18–36 h; recycle ratio = 0.75–1.5. Air requirements = 125 m3/kg of input BOD5.

High rate aeration activated sludge, Backmix with recycle: mean cell residence time = 5–10 d; food/microorganism ratio = 4.5–17 mg BOD5/s kg MLVSS; volumetric loading = 1.6–16 kg BOD5/m3; MLSS = 4–10 g/L; residence time = 0.5–2 h; recycle ratio = 1–5. Air requirements = 25–100 m3/kg of input BOD5.

xTrouble Shooting

Conventional activated sludge: “Increase in sludge volume index, ‘bulking’”: faulty design preventing plug flow/insufficient oxygen/lack of nutrients/high density inerts in feed. “Decrease in sludge volume index”: high concentration of dissolved organics in feed. “Sludge rises”: excessive nitration. “Frothing”: decrease in aeration suspended solids/increase in surfactants in feed/lipids in influent/aeration i design/increase in temperature. “Too much solids in effluent”: sludge blanket accumulation/return rate too low/too high overflow rate/bulking. “Too much BOD5 in effluent”: insufficient oxygen supply/too much solids in effluent/bulking. “No nitrification”: low solids retention time/not enough oxygen/wrong pH/toxic substance in influent. “Too much phosphors in effluent”: bulking/insufficient chemical addition.

2766 Reactors

6.33

STR: PFTR with Large Recycle

Reactor with external circulation, see also “loop reactor”, Sections 6.5 and 6.7.

x Area of Application

Phases: any. Recycle ratio = 20/1 gives backmix. Only exceed this recycle ratio if this is required for heat transfer. Low reaction rates; provides good mixing, cooling inside or outside the reactor. Large circulation rate prevents the buildup on walls as in slurry polymerization. Good backmixing and heat removal; suitable for slow reactions.

6.34

Reaction Injection Molding and Reactive Extrusion

x Area of Application

Phases: Liquid, liquid–liquid. Viscosities I 1000 mPa s; time for reaction to gel under adiabatic conditions i 0.1 s; small capacity: 0.150–2 kg/s.

x Guidelines

Viscosity 10–100 mPa s to prevent bubbles; Re i 300; fill time i 1 s and less than the reaction time to gel under adiabatic conditions. Mold temperature I 100 hC (or I 200 hC for high temperature operation). Mold temperature plus the adiabatic reaction exotherm must not exceed the degradation temperature. Reaction should be 95 % complete in I 3 min.

xGood Practice

Easy mold release.

xTrouble Shooting

“Inadequate mixing of liquid reactant with polymer”: liquid flowrate too high/screw channel under injection not full of polymer/faulty screw design. “Residuals in final polymer i design”: vent temperature too low/screw speed too low/polymer feed rate too high/screw design does not provide enough shear/vent pressure too high. “Polymer has crosslinked or degraded”: screw rpm too high/degree of fill too low/feedrate too low/heat zone temperatures set too high/screw design fault giving excessive shear/[screw tip pressure too high]*.

“Extruder torque excessive”: throughput too high/screw speed too low/heat zone temperatures set too low/faulty screw design. “Unable to melt material”: throughput too high/screw speed too low/faulty screw design/material too slippery. “Residence time too short”: throughput too high/[degree of fill too high]*/faulty screw design. “Residence time too long”: throughput too low/[degree of fill too low]*/ faulty screw design. “Gels or crosslinked materials”: localized initiator concentration too high/[melt temperature too high]*.

6.35 Reactive Distillation, Extraction, Crystallization 277

[Degradation of melt in extruder]*: [ RTD too wide]*/barrel temperature too high/ screw speed too high (causing overheating and shear damage)/oxygen present/ [oxidation]*/nitrogen purge ineffective/wrong stabilizer/wrong screw/flows not streamlined/stagnation areas present/extruder stopped when temperatures i 200 hC/copolymer not purged with homopolymer before shutdown/[residence time too long]*.

[Degree of fill too high]*: feed rate too high/screw speed too slow.

[Melt temperature too high]*: screw speed too high/exit barrel zone temperatures too high/screw tip pressure too high/degree of fill too low/[shear intensity too high]*/heat zone temperatures set too high/[screw tip pressure too high]*.

[RTD too narrow]*: [degree of fill too high]*

[Screw tip pressure too high]*: screens plugged/die or adapter or breaker plates too restrictive and give too much Dp/[polymer viscosity too high]*/temperatures in die assembly too low/barrel temperature too low/screw speed too high/[shear intensity too low]*/lubricant needed/flow restriction/throughput too high/die land too short/cold start/[degradation of melt in extruder]*.

[Shear intensity too low]*: screw speed too low/faulty screw design. For other symptoms see Section 9.11.

6.35

Reactive Distillation, Extraction, Crystallization

Reactive distillation

Gas–liquid reaction with catalytic solid. Include the catalyst with structured packing in a distillation column. Related topic: distillation, Section 4.2.

x Area of Application

Phases: Gas–liquid, gas–liquid–catalytic solid.

Gas–liquid plus catalytic solid: Use when (i) the reaction occurs in the liquid phase (in the presence or not of homogeneous catalyst) or at the catalyst interface; (ii) temperatures and pressures for reaction are consistent with distillation conditions; (iii) reactions are reversible equilibrium; not irreversible; (iv) not for supercritical, gas phase reactions, or solid reactants or products, high temperatures or pressures. Minimizes catalyst poisoning, lower pressure than fixed bed. Used for hydrogenation reactions and MTBE and acrylamide production. For example, 90 % conversion via reactive distillation contrasted with 70 % conversion in fixed bed option.

Liquid with homogeneous catalyst: etherification, esterification

Liquid–liquid: HIGEE for fast, very fast and highly exothermic liquid–liquid reactions such as nitrations, sulfonations and polymerizations.

Equilibrium conversion I 90 %. Use a separate pre-reactor when the reaction rate at 80 % conversion i 0.5 initial rate.

278 6 Reactors

x Guidelines

Use concentration profiles developed from either equilibrium or nonequilibrium reaction-separation to identify the reactive zone. The reflux ratio for reactive distillation is greater than for distillation. Use 1.2–1.4 q minimum. Damkohler11 = 1–20 and usually 1–10.

x Good Practice

Use such multifunctional equipment to intensify (H). If the product has a lower boiling temperature than the reactant; feed to the reboiler and need only the rectification section of column. If the reactant has a lower boiling temperature than the product, feed at the top and need only the stripping section but consider withdrawal of product part way down the column.

Example: ethyl acetate [ex ethanol, acetic acid]; methylal [ex formaldehyde and methanol] methyl acetate [ex methanol, acetic acid] with sulfuric acid as catalyst; methyl-tert-butyl ether, MTBE [ex methanol, isobutene] IX resin catalyst.

Extractive fermentation:

combine solvent extraction with anaerobic fermentation for ethanol from grains or acetone-butanol from whey.

6.36

Membrane Reactors

x Area of Application

Phases: Gas–liquid, gas-liquid–catalytic solid, gas–liquid–biosolid. For equilibrium reactions where selective removal via membrane will shift equilibrium or use of membrane as catalyst. Use for organic reactions in inorganic membranes Pd, alumina ceramic or liquid membranes. Use where we can selectively shift the equilibrium by selectively removing products (dehydrogenations, of cyclohexane to benzene, of ethyl benzene to styrene); or by controlling the addition of reactants (oxidations, hydrogenations, oxidative dehydrogenation, of ethane to ethylene) or whenever trickle bed reactors, Section 6.17, are considered.

x Guidelines

Try to match permeation rate and reaction rate.

Gas–liquid–biosolid: Bubble-free membrane gassing: gas diffuses into the media without bubbles. Used for shear-sensitive animal cell cultures (ex insect cells) and for systems containing serum that are prone to foaming. Use 10 to 25 m2/m3 for volume I 150 L. Enzyme membrane reactor: Power: 10 kW/m3; maximum volume 0.5 m3. Membrane allows diffusion of gas into the liquid without having to use bubbles.

References 279

6.37

Liquid Piston Reactor

x Area of Application

Phases: Gas–liquid fast reaction when the upstream equipment operates under a vacuum. The liquid piston draws the vacuum with the vapor reacting with the liquid sealing the pump.

x Guidelines

The example is the reaction between ketene and acetic acid to make acetic anhydride.

References

Bartholomew, C.H., Farrauto R. J., Funda-

mentals of Industrial Catalytic Processes, 2nd

edn., Wiley-Interscience, Hoboken, NJ,

2006.

Chauvel, A., Lefebrve, G., Petrochemical

Processes, Vol. 1 and 2, Gulf Publishing,

Houston, 1989.

Doraiswamy, L.K., Organic Synthesis Engi-

neering, Oxford, London, 2001.

Horak, J., Pasek, J., Design of Industrial

Chemical Reactors from Laboratory Data,

Heyden, London, 1978.

Moulijn, J.A., Makee, M., van Diepen, A.,

Chemical Process Technology, John Wiley and Sons, Chichester, 2001.

Rase, H.F., Chemical Reactor Design for Process Plants, Vol. 1 and 2, John Wiley and Sons, New York, 1977.

Rase, H.F., Fixed Bed Gaseous Reactor Design and Diagnosis, Butterworths, Boston, 1990.

Trambouze, P., et al., Chemical Reactors: Design, Engineering, Operation, Editions Techniq, Paris, 1988.

7 Mixing

The type of mixing system used depends primarily on the phases present. For liquid systems, the mixing phenomena are different than those for gas–solid mixtures or for solids blending. The fundamentals for the mixing of liquids are described in Section 7.1, the mixing of immiscible liquids in Section 7.2, the mixing of liquid and solids in Section 7.3 and dry solids in Section 7.4.

Mixing of gas–liquid systems is discussed in bubble reactors, Section 6.13, aerated STR, Section 6.27 and static reactors, Section 6.6. Solids can be mixed by fluidization, but this is discussed under drying, Section 5.6 and fluidized reactors, Section 6.30. Thick pastes and foodstuffs are mixed in extruders for food stuffs and polymers and pugmills for clays, thick pastes and fertilizers, Section 9.11.

7.1 Liquids

(Thanks to Jesse Shen for his input to this and to Sections 7.2 and 7.3).

For the mechanical agitation of liquids (and liquid–gas, liquid–liquid and li- quid–solid systems), the fundamental principles are as follows. The impeller should be designed to provide the proper combination of pumping and shearing of the fluids required by the specific application.

–Pumping: the liquid volume pumped by the impeller = kpu Di3 N where kpu is a constant dependent upon the impeller; Di is the diameter of the impeller and N = rpm. For a three-bladed marine propeller whose pitch = Di, kpu = 0.5; many other types of impellers have smaller values, and therefore the marine propeller is one

of the good axial flow impellers. In general, impellers giving axial flow are used in about 70 % of the mixing applications.

–Shear. The shear provided by the impeller is characterized by the shear number = ks (NDi/D)2 (nb B/D) (n Di/H)0.6 where D is the tank diameter, nb the number of

baffles; B the effective baffle width; H the height of liquid in the tank; n the number of impellers on the drive shaft. The value of ks depends on the type of impeller; for three-bladed marine = 1; for 6-bladed turbine = 5.5; for three-bladed sweptback impeller = 7.5; for 45h blades = 10. For polymer reactors, typical shear numbers are in the range 8000 to 10 000.

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