PROBLEMS Chapter 6 Plant Design and Economics for Chemical Engineers Fifth Edition 6-1 The purch purchased cost of a she hellll--and nd--tube hea heatt ex exchanger changer (floating (floating-he hea ad and carbon rbon--
steel tube steel bes s) with 100 m2 of heating heating surfa surface ce was $4200 $4200 in 1990. What What wi willl be be th the 199 990 0 2 pur cha has sed cost of a simil imila ar heat ex exchanger with 20 m of hea eatin ting g surface if the the pur chas ased ed cos costt ca capacit pacity y exponent is is 0.60 for s for surf ace ar eas eas r angin ing g f r ro m J 0 to 40 m2? If the the pu purc rch hase ased d cost capacit capacity y expon pone ent f or this this type of excha exchange gerr is is 0. 0.8 81 fo for r s sur face face 2 areas r angin ing g from from 40 to 200 m , what will be be the purchase purchased d cost of a hea eatt exch exc hange ger r w wit ith h 100 m2 of hea heatin ting g sur sur face face in 2000 000? ? 6-2 Pl Plo ot the 2000 pu pur chas ased ed cos costt of of th the e shellll-a and-t nd-tu ube heat exc exch hange ger r o outlin line ed in Pro rob b.
6-1 as as a f unct unction of of th the e su surface ar ea ea f rom rom 10 to 20 200 m2. Note Note that the the pur chased cost cost cap ca pac acit ity y exponent is is not co constant ove overr the the r ange of surface area area reques requested. 6-3 The purchase purchased d and inst insta allation cos costs of so some me pieces pieces of equipment are gi given as a
function of weight r ath fun the er th tha an ca cap pacity. An ex examp amplle of this this is the in ins stalled cost costs of lar ge ge tanks anks.. The 1990 cost for an ins installed aluminum tank weighin eighing g 45 45,,000 kg kg wa was s $64 640 0,000 000.. Fo For r a size ra ran nge f r r om 90 90,,000 to 450, 450,000 kg, kg, th the e in ins sta tallle led d cost cost weight expo ex pon nent fo for r alu lum minum ta tank nks s is 0.93. If an alu lum min inu um tank we weighing ighing 300 00,,00 000 0 kg is requ re quir ir ed, what capi capital inves nvestment tment is is nee eed ded in th the e year year 2000? 2000? 6-4
The 1990 cos The costt for an an in ins stalled 30 304 stainl stainle ess stee teell tank weighin weighing g 135 135,,000 kg kg wa was s $1,100 100,,000. The The in ins sta talllled ed cost weigh weight exponent ex ponent fo for r s stai ainl nle ess st s tee eell ta t anks is 0. 0.88 for a for a size ran range f r ro m 100, 100,000 to to 300, 300,000 kg. kg. Wha Wh at weight of ins installlled ed stainl stainless ess st stee eell tank could ha have been been obta tain ine ed f or the the sam ame e ca capi pita tall inve inves stment as as in Pr ob. 66-3?
6-5 Th The e pu purcha rchas sed cos cost of a 5-m3 stain inlless steel tank in 1995 was $10 $10,,900. The 22-m-
diame dia mete terr ta tank is cyli cylindri ndrica call with a f lat top and and bot botttom om.. If th the enti entire outer outer s surface of the the tank ta nk is i s to be cover covere ed wit ith h 0.050.05-m-thickne kness ss of magne magnesia bl blo ock, estimate th the curr cu rr ent total cos costt f or th the e in ins sta talllle ed and ins insul ulated ated tank. The The 1995 cost cost fo forr th the e 0.05 05--m-thick magne gnes sia bl block ock was $40 $40 per per s squ quare are meter whil while th the e la labor f or ins installi lling ng th the in ins sul ula atio ion n was $95 $95 per s per square meter . 6-6 A one-s one-stor y ware wa reh house 36 m by 18 m is to be added to an ex exist stin ing g pl plan antt. An asp aspha halt lt
pavement ser vice are pavemen rea a 18 m by b y 9 m wililll be added adj djac ace ent to t o the wareho arehou use. It will als al so be neces necessa sar r y to pu p ut in 150 liline nea ar m of railro railroa ad sid idiing to se ser r vic ice e th the e war wa r eho hou use. Utilitty se Utili ser r vice lin lines es ar e alre rea ady ava vailabl ilable e at th the e wa war r ehouse site te.. Th The e propose proposed d war wa r ehouse has a co con ncre crette f loo oor r and st stee eell fr ame, wa walllls s, and r oof. o of. No he hea at is neces nece ssar y, y, but lig lightin hting g and and spr inklers inklers mu must be ins nsttalllled ed.. Estimate th the to total cos costt of the the pr opose osed d addition. addition. Consult App pp.. B of th the 4t 4th ed. ed. f or or neces necessary cos costt data. data. 6-7 The pu pur chase ased d cos costt of of equipment equipment for a for a sol so lid pr oce cess ssing ing plant is $500 500,,000 000.. The pl plant
is to be con constr uct cte ed as an additi ditio on to an exi xist stiing plant nt.. Estimate the total ca capit pita al investment inves tment and the fixedfixed-cap capiital investment f or o r the pl plant. What perc rce ent nta age and amount of the f ixed ed--capita tall in investme vestment nt ar e due to co cos st fo forr en engi gine neer er ing and super vision ision,, and what pe per cent centage age an and amount amount fo forr the the con contractor 's fee?
6-8 The purchased-equipment cost for a plant which pr oduces pentaer ythritol (solid-f luid
pr ocessing plant) is $300,000. The plant is to be an addition to an existing formaldehyde plant. The ma jor part of the building cost will be for indoor construction. The contractor 's fee will be 7 percent of the direct plant cost. All other costs ar e close to the average values found for typical chemical plants. On the basis of this infor mation, estimate the total direct plant cost, the fixed-capital investment, and the total capital investment. 6-9
Estimate by the turnover r atio method the f ixed-capital investment requir ed in 2000 for a proposed sulf uric acid plant (batter y-limit) which has an annual capacity of 1.3 x 108 kg/yr of 100 percent sulf uric acid (contact-catalytic pr ocess), using the data f ro m Table 6-11, when the selling pr ice f or the sulf ur ic acid is $86 per metric ton. The plant will operate 325 days/year. Repeat the calculation, using the cost capacity exponent method with data from Table 6-11.
6-10 The total capital investment for a chemical plant is $1 million, and the working capital
is $100,000. If the plant can produce an aver age of 8000 kg of f inal pr oduct per day during a 365-day year , what selling price in dollar s per kilogr am of pr oduct would be necessar y to give a turnover r atio of 1.0? 6-11 A pr ocess plant was constructed in the Philadelphia area (Mid-Atlantic) at a labor
cost of $425,000 in 1990. What would be the labor cost for the same plant located in the Miami, Florida, area (south Atlantic) if it wer e constructed in late 1998? Assume, for simplicity, that the relative labor rate and r elative productivity f actor have remained constant. 6-12 A company has been selling a soap containing 30 percent by weight water at a price
of $20 per S O kg f .o.b. (i.e., the customer pays the f re ight char ges). The company offer s an equally effective soap containing only 5 percent water . The water content is of no importance to the laundry, and it is willing to accept the soap containing 5 per cent water if the delivered costs are equivalent. If the f reight r ate is $l.50 per 50 kg, how much should the company charge the laundr y per 50 kg f .o.b. f or the soap containing 5 per cent water? 6-13 The total capital investment f or a conventional chemical plant is $1,500,000, and the
plant produces 3 million kg of product annually. The selling pr ice of the pr oduct is $0.82/kg. Wor king capital amounts to 15 per cent of the total capital investment. The investment is f r om company funds, and no inter est is charged. Deliver ed r aw mater ials costs for the product are $0.09/kg; labor , $0.08/kg; utilities, $0.05/kg; and packaging, $0.008/kg. Distribution costs ar e 5 percent of the total pr oduct cost. Estimate the following: a. b. c. d.
Manuf actur ing cost per kilogr am of product. Total product cost per year Pr ofit per kilogram of pr oduct befor e taxes Profit per kilogram of product af ter income taxes at 35 per cent of gr oss prof it.
6-14 Estimate the manuf acturing cost per 100 kg of pr oduct under the following conditions:
Fixed-capital investment = $4 million. Annual production output = 9 million kg of product. Raw materials cost = $0.25/kg of pr oduct. Utilities: 800-kPa steam = 50 kg/kg of product. Pur chased electric power = 0.9 kWh/kg of product. Filtered and sof tened water = 0.083 m3/kg of pr oduct. Operating labor = 12 per sons per shift at $25.00 per employee-hour . Plant oper ates three hundr ed 24-h days per year . Cor r osive liquids ar e involved. Shipments are in bulk carload lots. A lar ge amount of dir ect super vision is required. Ther e ar e no patent, r oyalty, interest, or rent char ges. Plant over head costs amount t o 5 0 p er cent of the cost for oper ating labor, super vision, and maintenance. 6-15 A company has direct production costs equal to 50 per cent of total annual sales, and
f ixed char ges, overhead, and general expenses equal to $200,000. If management pr oposes to increase present annual sales of $800,000 by 30 per cent with a 20 per cent increase in fixed charges, overhead, and general expenses, what annual sales amount is required to provide the same gr oss earnings as the present plant oper ation? What would be the net prof it if the expanded plant wer e oper ated at f ull capacity with an income tax on gr oss earnings of 35 percent? What would be the net pr of it for the enlarged plant if total annual sales remained at $800,000? What would be the net profit f or the enlar ged plant if the total annual sales actually decreased to $700,000? 6-16 A pr ocess plant making 5000 kg/day of a product selling for $1.75/kg has annual
var iable pr oduction costs of $2 million at 100 percent capacity and fixed costs of $700,000. What is the f ixed cost per kilogr am at the br eakeven point? If the selling pr ice of the pr oduct is incr eased by 10 percent, what is the dollar increase in net prof it at f ull capacity if the income tax rate is 35 per cent of gr oss ear nings? 6-17 A rough rule of thumb for the chemical industr y is that $1 of annual sales r equir es $2
of fixed capital investment. In a chemical pr ocessing plant wher e this r ule applies, the total capital investment is $2,500,000, and the working capital is 20 percent of the total capital investment. The annual total pr oduct cost amounts to $1,500,000. If the income tax r ates on gross earnings total 35 per cent, determine the f ollowing: a. Per cent b.
of total capital investment r etur ned annually as gr oss earnings Percent of total capital investment r etur ned annually as net profit.
6-18 The total capital investment f or a pr oposed chemical plant, which will pr oduce
$1,500,000 wor th of goods per year , is estimated to be $1 million. It will be necessar y to do a considerable amount of r esearch and development (R&D) work on the pr o ject bef or e the final plant can be constr ucted, and management wishes to estimate the permissible research and development costs. It has been decided that the after tax
return from the plant should be sufficient to pay off the total capital investment plus all research and development costs in 7 year s. A retur n af ter taxes of at least 12 per cent of sales must be obtained. Because R&D is an expense and the company's income tax rate is 35 per cent of gross earnings, only 65 percent of the f unds spent on R&D must be r ecover ed af ter taxes are paid. Under these conditions, what is the total amount the company can af f ord to pay f or research and development? 6-19 A chemical pr ocessing unit has a capacity for producing I million kg of a pr oduct per
year . Af ter the unit has been put into oper ation, it is f ound that only 500,000 kg of the pr oduct can be sold per year . An analysis of the existing situation shows that all fixed and other invariant char ges, which must be paid whether or not the unit is oper ating, amount to 35 percent of the total pr oduct cost when operating at f ull capacity. Raw material costs and other pr oduction costs that are directly proportional to the quantity of production (i.e., constant per kilogram of pr oduct at any pr oduction rate) amount to 40 percent of the total pr oduct cost at full capacity. The remaining 25 per cent of the total pr oduct cost is for variable overhead and miscellaneous expenses, and the analysis indicates that these costs are dir ectly pr oportional to the production r ate during oper ation r aised to the 1.5 power . What will be the per cent change in total cost per kilogram of pr oduct if the unit is switched f ro m the original design r ate of I 06kg/yr of pr oduct to a time and r ate schedule which will produce 0.5x 106 kg or "half that amount" of pr oduct per year at the least total cost?
Proyectos para Ingeniería Química Facultad de Ingeniería Departamento de Ingeniería Química Universidad Nacional Autónoma de Honduras
