SUMMARY The process purpose is to produce acetone from isopropyl alcohol (IPA) at the given conditions. This report is formed, some properties, manufacturing process of acetone. In manufacturing process, feed drum, vaporizer, heater, reactor, furnace, cooler, condenser, flash unit, scrubber, acetone and IPA columns are used. This profile envisages the establishment of a plant for the production of acetone with a capacity of 100 tons per annum. The present demand for the proposed product is estimated at 70 tons per annum. The demand is expected to reach at 137.7 tones by the year 2017. The plant will create employment opportunities for 20 persons. The total investment requirement is estimated at Birr 6.17 million, out of which Birr 2.84 million is required for plant and machinery. The project is financially viable with an internal rate of return (IRR) of 14 % and a net present value (NPV) of Birr 1.71 million, discounted at 8.5%.
NOMENCLATURE MW=Molecular Weight [kg/kmol] N = mole [mol/h] Y = mol or mass fraction of gas stream X = mol or mass fraction of liquid stream P Tn = Total Pressure [bar] Pi*n= Vapour Pressure of Component [bar] Pv* = Vapour Pressure [bar] F = Feed Flow Rate [k mol/h] V = Flow Rate of Vapour [kmol/h] L = Flow Rate of Liquid [kmol/h] T = Temperature [° C] ∆ Hvap = Latent Heat of Vaporization [kJ/kg] TC = Critical Temperature [° C] PC = Critical Pressure [bar] Tb = Normal Boiling Point [° C] Q = Heat [kJ] M = Mass Flow Rate [kg/h] K = Activity Coefficient
Introduction:Acetone is the organic compound with the formula (CH3)2CO, a colorless, mobile, flammable liquid, the simplest example of the ketones. Acetone is miscible with water and serves as an important solvent in its own right, typically as the solvent of choice for cleaning purposes in the laboratory. About 6.7 million tons were produced worldwide in 2010, mainly for use as a solvent and production of methyl methacrylate and bisphenol A. Familiar household uses of acetone are as the active ingredient in nail polish remover and as paint thinner. It is a common building block in organic chemistry. Acetone is naturally produced and disposed of in the human body as a result of normal metabolic processes. It is normally present in blood and urine. Diabetic people produce it in larger amounts. Reproductive toxicity tests show that it has low potential to cause reproductive problems. In fact, the body naturally increases the level of acetone in pregnant women, nursing mothers and children because their higher energy requirements lead to higher levels of acetone production. Ketogenic diets that increase acetone in the body are used to reduce epileptic attacks in infants and children who suffer from recalcitrant refractory epilepsy. Acetone (dimethyl ketone, 2-propane, CH3COCH3) formulation weight 58,079 is the simplest and the most important of the ketones. It is a colorless, mobile, flammable liquid with a mildly pungent and somewhat aromatic odour. It is miscible in all proportions with water and with organic solvents such as ether, methanol, ethyl alcohol, and esters. Acetone is used as a solvent for cellulose acetate and nitrocellulose, as a carrier for acetylene And as a raw material for the chemical synthesis of a wide range of products such as ketene, Methyl methacrylate, bisphenol A, diacetone alcohol mesityl oxide, methyl isobutyl ketone, Hexylene glycol (2-methyl-2, 4-pentanediol), and isophorone. Acetone is produced in various ways; 1. The Cumene Hydro peroxide Process for Phenol and Acetone 2. Isopropyl Alcohol Dehydrogenation 3. Direct Oxidation of Hydrocarbons to a Number of Oxygenated Products Including Acetone 4. Catalytic Oxidation of Isopropyl Alcohol 5. Acetone as a By-Product of the Propylene Oxide Process Used by Oxirane 6. The p-Cymene Hydro peroxide Process for p Cresol and Acetone 7. The Diisopropylbenzene Process for Hydroquinone (or Resorcinol) and Acetone In this report isopropyl alcohol dehydrogenation was investigated.
PHYSICAL AND CHEMICAL PROPERTIES: Appearance: -
Liquid. Clear.
Molecular wt.:-
58.079
Colour: -
Colourless.
Density/specific gravity (g/ml):-
0.79 Temperature (°C): 20
Melting Point
-94.60C
Boiling Point
56.130C (at 760 mm Hg)
Vapour Pressure: -
24 .7 KP at Temperature (°C):
20Evaporation Rate: -
.6
Volatile by vol. (%):-
10
Solubility description: -
Miscible with water.
Solubility Value (g/100g H 2O20°C ):Auto Ignition Temp. (°C):-
100 540
Flammability limit (lower) (%):-
2.1
Flammability limit (upper) (%):-
13.0
Stability and Reactivity: Stability: -
Stable under normal conditions of use.
Conditions to avoid: -
Avoid contact with: Strong oxidising agents. Avoid Contact with acids. Avoid heat, flames and other
. Materials to avoid: -
Sources of ignition Potassium sulphate, sodium hydroxide, sulphuric acid, Nitric acid, hydrogen peroxide, chloroform, activated Carbon, Bromine.
Hazardous Decomp.Product -
Thermal decomposition or burning may release oxides Of carbon and other hazardous gases or vapours
.
Uses-: About a third of the world's acetone is used as a solvent, and a quarter is consumed as a precursor to methyl methacrylate. Solvent use: Acetone is a good solvent for most plastics and synthetic fibers including those used in laboratory bottles made of polystyrene, polycarbonate and some types of polypropylene. It is ideal for thinning fibreglass resin, cleaning fiberglass tools and dissolving two-part epoxies and superglue before hardening. It is used as a volatile component of some paints and varnishes. As a heavy-duty degreaser, it is useful in the preparation of metal prior to painting; it also thins polyester resins, vinyl and adhesives. It is also useful for high reliability soldering applications to remove solder rosin after soldering is complete. This helps to prevent the Rusty bolt effect from occurring due to dirty solder contacts. Storage of acetylene Although flammable itself, acetone is also used extensively as a solvent for the safe transporting and storing of acetylene, which cannot be safely pressurized as a pure compound. Vessels containing a porous material are first filled with acetone followed by acetylene, which dissolves into the acetone. One litter of acetone can dissolve around 250 litters of acetylene. Methyl methacrylate This application begins with the initial conversion of acetone to acetone cyanohydrins: (CH3)2CO + HCN → (CH3)2C (OH) CN In a subsequent step, the nitrile is hydrolyzed to the unsaturated amide, which is esterified: (CH3)2C (OH) CN + CH3OH → CH2= (CH3) CCO2CH3 + NH3 The third major use of acetone (about 20%) entails its condensation with phenol to give bisphenol A (CH3)2CO + 2 C6H5OH → (CH3)2C (C6H4OH) 2 + H2O
Bisphenol A is a component of many polymers such as polycarbonates, polyurethanes, and epoxy resins. Medical and cosmetic uses Acetone is used in a variety of general medical and cosmetic applications and is also listed as a component in food additives and food packaging. Acetone is commonly used in chemical peeling. Common agents used today for chemical peels are salicylic acid, glycolic acid, 30% salicylic acid in ethanol, and trichloroacetic acid (TCA). Prior to chemexfoliation, the skin should be cleaned properly and excess fat removed. This process is known as defatting. Acetone, Septisol, or a combination of these agents is commonly used in this process. Laboratory uses In the laboratory, acetone is used as a polar aprotic solvent in a variety of organic reactions, such as SN2 reactions. The use of acetone solvent is also critical for the Jones oxidation. It is a common solvent for rinsing laboratory glassware because of its low cost and volatility. H\however, it does not form an azeotrope with water (see azeotrope (data)). Despite its common use as a supposed drying agent, it is not effective except by bulk displacement and dilution. Acetone can be cooled with dry ice to −78 °C without freezing; acetone/dry ice baths are commonly used to conduct reactions at low temperatures. Acetone is fluorescent under ultraviolet light, and its vapour may be used as a fluorescent tracer in fluid flow experiments. Domestic and other niche uses Acetone is often the primary component in cleaning agents such as nail polish remover. Ethyl acetate, another organic solvent, is sometimes used as well. Acetone is a component of superglue remover and it easily removes residues from glass and porcelain. It can be used as an artistic agent; when rubbed on the back of a laser print or photocopy placed face-down on another surface and burnished firmly, the toner of the image transfers to the destination surface. Make-up artists use acetone to remove skin adhesive from the netting of wigs and moustaches by immersing the item in an acetone bath, then removing the oftened glue residue with a stiff brush.
MARKET TREND -: Past Supply and Present Demand The country's requirement for acetone is totally met through import. Data obtained from the Ethiopian Customs Authority with regard to import of acetone for the period covering 1997 2011 is given in Table-
IMPORTANCE OF ACETONE YEAR
QUANTITY(Mt.Tons)
1997
41.6
1998
90.6
1999
52.7
2000
24.7
2001
154.3
2002
34.0
2003
34.3
2004
57.7
2005
47.5
2006
84.2
2007
70.5
2008
74.9
2009
80.2
2010
85.8
2011
91.8
Projected Demand -: Acetone is used as a solvent in the production of paint, varnish, lacquer, cellulose acetate, potassium iodide and permanganate. It is also used to clean dry parts of precision equipments, delusterant for cellulose acetate fibre and specification testing of vulcanized rubber products. This clearly indicates that demand for acetone is directly related with the development of the industrial sector. Taking this in consideration, annual average growth of 7% is applied to forecast the future demand. The forecasted demand up to the year 2017 is given in Table 3.2. 55-6 import figures were much higher than the imports in the following years. In 1998, the import figure was about 90.6 tonnes while in the following years, i.e., 1999 and 2000 the import figure dropped to 52.7 tonnes and 24.7 tonnes respectively. Similarly, import figure in the year 2001 was about 154 tones while in the following four consecutive years, i.e., from 2002 - 2005 import ranges from only 34 tonnes to about 58 tonnes. This probably indicates that the high imports in some years were used as buffer stocks for the following years. Hence, some portions of the imports were distributed among the subsequent years in which recorded import figures were found to be comparatively low. By looking to the above argument, the present effective demand is estimated using the following methodology. The average import figures in the recent past six years, i.e., 2001- 2006 is taken as an effective demand for the year 2007 since the product is directly related with the growth of the manufacturing sector, an annual average growth rate of 7% (which is recorded by the industrial sector in the past) is applied to arrive at the current (year 2007) demand.
PROJECT DEMAND OF ACETONE YEAR
QUANTITY(Mt.Tons)
2012
98.2
2013
105.1
2014
112.4
2015
120.3
2016
128.7
2017
137.7
METHODS OF PRODUCTION:(a) Catalytic Dehydrogenation of Isopropanol (b) Oxidation of Isopropyl benzene (c) Co product of Glycerine- H2O2 process (d) Oxidation of Butanol (e) Oxidation of Propylene (a) Acetone by oxidation of Propylene: A process for acetone production by direct oxidation of propylene using air. In this process the catalysis consists of a solution of copper chloride containing small quantities of palladium chloride. The overall reaction is as follows C3H6+1/2O2
CH3COCH3
(b) Oxidation of Butanol: Catalytic oxidation of n butane using either cobalt or manganese acetate produces acetic acid at 75-80% yield. By products of commercial value are obtained in variable amounts. In the Celanese process the oxidation reaction is performed at a temperature range 150-2250C and pressure of approx 505 atm. CH3CH2CH2CH3 + O2
CH3COOH + CH3COCH3
(c) Co product of Glycerine- H2O2 process: When Glycerine is produced from propylene via acrolein then acetone is produced as a by product. CH3CH═CH2 + H2O
CH3CHOHCH3 + O2
CH3COCH3 + H2O2
(d) Oxidation of Isopropyl Benzene (Cumene):Cumene is synthesised from propylene and benzene, followed by oxidation for the formation of hydro peroxide and splitting the same into acetone and phenol. The crude products are then fractionated to get pure acetone and phenol.
(e) Dehydrogenation
of
Isopropanol:
Acetone
is
produced
from
catalytic
dehydrogenation of isopropanol. The catalyst used in this process is ZNO.The crude product obtained from this process is fractioned and pure product is obtained. (CH3)2CHOH
(CH3)3CO + H2
The acetone produced in the reactor passes into a phase separator and then into a separation system that includes one stripping and two distillation columns. A recycle stream takes a mixture of unreacted isopropyl alcohol and water, with a trace amount of acetone, back into a mixer that feeds the reaction system. Using the catalyst which will be employed throughout this analysis, the reaction is first order with respect to the concentration of isopropanol and has an Arrhenius dependence on temperature with E=72.38 MJ/kmol and k=351,000 cubic m gas/cubic m reactor sec.
Reason
for selecting
the
process: (Catalytic
dehydrogenation of
Isopropanol): Acetone production from Cumene process is a serious competitor for the isopropanol dehydrogenation process. Catalytic dehydrogenation of isopropanol can be chosen as a synthetic route when high-purity acetone is required, such as in biomedical applications. In this process 88% of isopropanol is recycled so this process is cost effective. Catalytic dehydrogenation of isopropanol gives approx 99% pure product. Catalytic dehydrogenation of isopropanol: In the simplified process, an aqueous solution of isopropyl alcohol is fed into the reactor, where the stream is vaporized and reacted over a solid catalyst at 2 atm. The reactions occurring within the reactor are as follows: CH3-CHOH-CH3
Isopropyl alcohol (IP) CH3-CHOH-CH3 + ½ O2 IP
CH3-CO-CH3 Acetone (AC)
+
H2 Hydrogen (HY) CH3-CO-CH3 Acetone
+
H2O Water
Flow Sheet of Acetone Production
Process Description: Feed drum is a kind of tank used for the mixing of the recycle stream and feed stream. Recycle stream concentration was assumed to be same with the feed stream. The temperature of the feed stream is assumed to be 250C at 2 bar pressure, which is assumed to be constant. The temperature of recycle stream was calculated as 111.50C. The temperature of the leaving stream was calculated as 32.890C, by the energy balance around feed drum. In the vaporizer molten salt was used for heating. The temperature at the entrance of the unit is the temperature of the mixture leaving the feed drum, which is 32.890C. And the leaving temperature is the bubble point temperature of the mixture, which is 109.50C. The pressure is 2 bars, and assumed to be constant. Since the temperature leaving the vaporizer is not enough for the reaction a pre-heat was used. The unit is working at 2 bars, and assumed to be constant. The entrance and leaving temperatures are 109.50 C and 3250 C. The reactor was the starting point for the calculations. The temperature values for the entering and leaving streams were found from literature, which are 3250C and 3500C, respectively. The reaction taken place inside is endothermic, for this reason the reactor has to be heated. For heating, molten salt was used. The pressure is 1.8 bar, and assumed to be constant. The entrance temperature of the cooler is 350 0C and leaving is 94.70C. For cooling, water was used. Instead of water a refrigerant may be used. Better results may get. But since it costs too much, it wasn‟t chosen as the cooling material. From the temperature values it‟s easily seen that the load is on the cooler not on the condenser, for this process. But in reality the unit cannot cool that much, and the load is mostly on the condenser. In this process, the mixture cooled down to its dew point. The pressure is 1,5 bar, and assumed to be constant.- 5 - The temperature of the entering stream is the dew point and the leaving temperature is the bubble point of the mixture. In the condenser water was used as cooling material. In the calculation of the dew and bubble points Antoine Equation was used. Trial and error was used with the help of Excel. The mixture includes acetone, i- propyl -alcohol, water and hydrogen. But hydrogen was not taken into consideration in the calculations. Since the condensation temperature of hydrogen is very low, it is not condense in the condenser. It stays in the for this reasons it has no affect on bubble and dew point calculations. Also since it does not affect the temperature calculations it‟s not taken into consideration on mole and mass fraction calculations. The leaving and entering temperatures are 94.70 0C and 81 0C, respectively. The pressure is 1.5 bar, and assumed to be constant. Flash unit was assumed to be isothermal, for this reason temperature was not changed. It is 81 0C in the entrance and exit. The pressure is 1.5 bar, and assumed to be constant. By trial and error method, (V / F) value was found to be
0.2. The entrance temperature of the unit is the bubble point of the mixture, but if it was its dew point the (V/F) value would be much higher. Scrubber was assumed to be adiabatic. The temperature of water entering the unit was assumed to be 25 0C. The temperature of the off gas, including hydrogen and a very little amount of acetone, was assumed to 70 0C. But this assumption is too high, a lower temperature should have been assumed, since a lot of water is used in the unit. It should have been around 40 0C – 50 0C. The temperature of the leaving stream was found to be 28.1 0C.The pressure of the unit is 1.5 bar, and assumed to be constant
Raw Material Propylene or ISO-propyl alcohol is the only raw material used for manufacturing of acetone in the presence of a catalyst. Packaging materials are required for delivering this product. The annual materials requirement and cost of the plant is given in Table 4.1. ANNUAL CONSUMPTION OF RAW MATERIALS AND COST ANNUAL CONSUMPTION OF RAW MATERIALS AND COST Description Propylene Catalyst (silver or copper) Water Packaging Total
Unit of meas.
Qty.
Cost in '000 Birr F.C
tonnes " 3
m Barrel
120 0.5 80
918 17 -
625
935
L.C 162 3 0.26
T.C 1080 20 0.26
188 188 353.26 1288.26
7.2 MATERIAL BALANCE: 7.2.1 Material Balance on Reactor: CONVERSION = 90%
Nacetron5= 100*0.9 =90kmole/hr Nh25 =100*0.9 =90 kmole/hr NH2o 5 =49.25kmole/hr Nipa =100*0.1= 10 kmole/hr Ntotal= naceton +nh2o + nh2 5 +nipa =239.25kmole/hr
Yacetone =90/239.25= 0.376 Yh2 5=90/239.25 =.376 YH2o= 49.25/239.25= o.206 yipa=10/239.25 =0.042
7.2.2 Material Balance on Flash Unit:
It is assume that there is no change at temp. and pressure. Ki == pi*/pp= yi/xi
(at bubble point = 810c)
For Acetone Logp*aceton =7.0947 – 1161/ (224+81) P*aceton= 1651.6mmHg Kaceton =1651.6/ ((1.5/1.013)*760) = 1.467 For IPA Log p*= 8.37895- 1788.02/ (227.438+81) P*ipa =381`.89 mmHg Kipa = 381.89/1125.092 =0.339 For H2O Log p*H2O = 7.96681 – 1668.21/ (228+81) P*H2O = 369.89
KH2O = 369.89/1125.092 = 0.328 For Trail error F/V = 0.2 Ft= nacetone +nH2O + nipa =149.25 F=V+L V/F =0.2 Solving V = 29.85kmole/hr
, L= 119.4 Kmole/ hr
YV = K * xl F*ZF = Vx *yv + z* xl For Acetone Yv = 1.467 * xL 90=29.85 yv + 119.4* xL After solving Xl=0.551 Yv = 0.809 For IPA Yv = 0.339 * xL 10= 29.85 * yv + 119.4 * xl After solving Xl ==0.077
Yv = 0.026
For water Yv = 0.328 *xl 49.25 = 29.85 * yv + 119.4 * xl X l = o.381 Yv = o.125
At Stream 8: V= 29.85 kmol/hr. Yacetone= 0.809 Nacetone8= (0.809)*(29.85) = 24.148 kmol/hr Yipa= 0.026 Nipa8= 0.026*29.85= 0.766 kmol/hr YH2O =0.125 NH2O= (0.125)*(29.85) =3.731kmol/hr At Stream 9 L= 119.4kmol/hr Xacetone=0.551
nacetone= (0.551)*(119.4) = 65.789 kmol/hr
Xipa=0.077
nipa9= (0.077)*(119.4) = 9.149 kmol/hr
Xwater=0.381
nacetone= (0.381)*(119.4) = 45.491 kmol/hr
7.2.3 Material balance for Scrubber: T=(81oC) = 354.15 K, P=1.5bar Assume: 1/1000 of inlet acetone is off gas. Nacetone12= 0.024148 kmol/hr Nacetone10=24.148-0.024148=24.124kmol/hr
Ntotal= nacetone+nH2,8+nH2O+nipa
24.148+90+3.731+0.776 = 118.655 kmol/hr
nacetone12= nacetone12+nH2,12
0.024148+90 = 90.024kmol/hr
Yacetone=0.024148/90.024= 2.68*10-4 Yacetone8= 24.148/118.655 =0.203 Yacetone12/ Yacetone8=1-A/1-A6 M= e (10.92-3598/T)/P
Where A =L11/m* V8
take P=1.48
T=354.15
M= 1.445 Yacetone12/ Yacetone8=2.68*10-4/0.203 = 1.320*10-3= 1-A/1-A6 From trial error A is found is 3.523 L11= m*A*V8= 1.445*3.523*118.655 = 604.041 kmol/hr NH2O10= nH2O8+ nH2O11
3.731+604.041 =607.772 kmol/hr
Ntotal10= nacetone10+nH2,10+nipa10
24.124+607.772+0.776= 632.6724 kmol/hr
7.2.4 Material balance for Acetone Column Nacetone13= Nacetone9+nacetone10= 65.789+24.124= 89.913kmol/hr Nipa13= Nipa9+ Nipa10= 9.194+0.776 = 9.97 kmol/hr NH2o13= NH2o9+ NH2o10= 45.491+607.772=653.263 kmol/hr
Assume: 1/1000 of acetone is in bottom product. Nacetone15=89.913/1000= 0.089kmol/hr Nacetone14= 89.913-0.089= 89.824kmol/hr Since acetone purity is 99%. Nipa14=89.824*(0.01/.99)= 0.907kmol/hr Nipa15=nipa13-nipa14=9.97-0.907=9.063kmol/hr
NH2O15=nH2o13=653.263kmol/hr 7.2.5 Material Balance for IPA column:
All the ipa is at the top product Nipa17 = nipa 15 = 9.063 kmole/hr Nacetone17 = nacetone15 = 0.089kmole/hr Assume the composition of the recycle stream is as feed stream so that Yacetone = 0.33
yipa =o.67
N H2O 17 = 9.063 * 0.33/o.67 = 4.469kmole/hr nwater
=
nwater - nwater = 653.263 - 4.464 = 648.729kmole/hr
7.2.6 Material Balance for Feed Drum: INPUT = OUTPUT Nipa 12 = nipa - nipa 17 = 100 - 9.063 = 90.933kmole/hr NH2O = nH2O + nh2o 17 NH2O = 49.25 - 4.464 = 44.786kmole/hr Sience 115000tonns/day acetone is wanted to produce all of these calculation should be correlated as this amount, these new value are shown in lable Amount = 89.824 kmole/hr * 58.08 kg/1 * 1 ton/1000 * 8760/1 yr
= 45700.726 tpy Scale factor Sf = (115000ton/yr)/ 45700.726 = 2.516
7.3 ENERGY BALANCE 7.3.1 For Feed Drum
MH2O=2029.966kg/hr
1
T=250C Mipa=13749.785kg/hr
Feed Drum
2
T=32.890C
Mipa=15120.159kg/hr
Mwater=2232.293kg/hr 3 Mipa=1370.369kg/hr
Tref =250C
Cp.pia=2497kj/kg
Cp.water=4178kj/kg
For stream 1,2 and 17 calculate Cpmix Cpmix = (2497*0.87)+(4178*0.13) =2715 kj/kg Mtotal1=13749.785+2029.966= 15779.75 kg/hr
Mwater=202.326kg/hr
Mtotal2=15120.154+2232.293=17352.447kg/hr Mtotal3=1370.369+202.326= 1572.695 kg/hr Qin=Qout 15779.75*2.715*(25-25) +1572.695*2.715*(111.5-25) = 17352.447*2.715*(T-25) T=32.830C
7.3.2 For Vaporiser:
T=32.830C MIPA =15120.15kg/hr MH2O =2232.293kg/hr T =109.50C Mipa=15120.154 Kg/hr Mwater = 2232.293kg/hr At 32.83 0c Cpipa = 145kj/kmole K =
2.413 kj/kg K
CpH2o = 4.179 kj/kg K For Water Tc = 508.3 K Tb = 394.399K ΔHf = 39838 kj/kmole ΔHvap ,H2O = H [(Tc-T)/(Tc-Tb)]o.38 = 41370.970 kj/kmole
= 2296.4731 kj/kg For IPA Tc = 647.3 K Tb = 375K ΔHf = 40683kj/kmole ΔH vap , ipa = 40683[(647.3k-382.5k)/(647.3k-375k)]0.38 =40253.505 kj/kmol = 66982kj/kg Q = (mipa * Cpipa * Δ T) + ( mwater * Cpw * ΔT) + (mw *Δ H vep, wat) + (mpipa * ΔHvap ,ipa) = 9.652 * 106 kj Molten Salt: We assume Δ T = 20 Q = m * Cpmolt.salt * Δ T 9.652*10^6 kj = 156 kj/kg * m * (20) M = 309.358 tons 7.3.3 Pre Heater:
Heater T=109.50C
T=3250C
Mwater=2232.253kg/hr
Mwater=15120.154kg/hr
Mipa=15120.154kg/hr
Mipa=2232.293kg/hr
Tref=109.50C
Cp,pia=24.6kj/kgk
CpH2O=2019kj/kgk
Q=(mwater*Cpwater*∆T)+(mipa*Cpipa*∆T)
=[(2232.293*2.468*(325-
109.5)+(15120.154*2.019*215.5)] = 1.845*106 kj Molten Salt: We assume ∆T= 1500C Q=m*Cp molten salt*∆T= 1.845*106=156*m*150 M=7.855 ton 7.3.4 For Reactor: (CH3)2CHOH
(CH3)2CO+ H2
COMPOUND Nin kmol/hr
Hf kj/kmol
Nout kmol/hr
(CH3)2CHOH
251.6
-272.290
25.16
CH3)2CO
0
-216.685
226.44
H2
0
0
226.44
T=3250C
T=3500C
Reactor
MH2=435.144kg/hr Mipa
=1512.015kg/hr Mipa=15120.154kg/hr Mwater=2232.293kg/hr Mwater= Macetone=13151.635kg/hr
2232.293kg/hr
∆Hin ipa= -272.29+25∫325(32.427+1.886*10-1T+6.405*10-5T2-9.261*10-8T5)dT ∆Hin ipa= -272.29+20.104 = -252186 kj/mol -27229+25∫350(32.427+1886*10-1T+6405*10-5T2-9261*10-8T3)dT
∆Hout
ipa=
∆Hout
ipa= -249.691
kj/kmol
∆Hout acetone= -216.685+25∫350(71.96+20.1*10-2T+12.78*10-5T2+3.476*10-8T3)dT ∆Hout acetone= -182.745 kj/mol ∆Hout
350 (28.84*10-3+0.3288*10-8T2+0.00765*10-5T-0.8698*10-12T3)dT H2= 25∫
∆Hout
H2=9.466
kj/kmol
∆Hr0=(-216.685kj/kmol)-(-272.29)kj/kmol ∆Hr0= 55.605kj/kmol ∆Hr=226.44*55.685/1 =12591kj Q= ∑outniHi - ∑inniHi+∆Hr Q= [ 25.16( -249.691)+226.44(-182.745)+226.44(9.466)] – [252.6(-252.106)] +2591.196 Q=30521.67 kj Molten Salt Cp(molten salt b/w 3600C- 4100C) = 156kj/kg Q=m*Cp*∆T 30521.67=156*m*50 M=391.300kg/hr
7.3.5 For Cooler T = 3500C MIPA = 1512.015kg/hr MH2O = 2232.293kg/hr
T= 94.70c ,
Macetone = 13151.635kg/hr
mipa =1512.015kg/hr
MH2 = 455.144kg/hr
m H2O =2232.293
kg/hr Macetone =13151.635 kg/hr MH2 455.144kg/hr
Tref = 94.70c CpH2 = 12.608 kj/kg K CpH2O= 2.035 kj/kg K Cpipa =2.536kj/kg K Cpacetone = 1.096 kj/kg K We know Q =[(mH2 *CpH2) + (mH2O * CpH2O) + (mipa * Cpipa) + (macetone * Cpacetone)] * del T Q = - 10.123 * 106 kj Water Δ T water = 35- 20 =20 CpH2O =4.179 kj/hr
=
Q = m * CpH2o * Δ T 10.123 *106kg = 4.179kj/kg * m * 20
m = 121.117 ton/hr
7.3.6 For Condencer:
T
94.70C
=
T = 81 0c MIPA =1512.O15Kg/hr MH2O =2232.293 kg/h
mh2o= 2232.293kg/hr
Macetone = 1315.635kg/hr
m acetone
=13151.635kg/hr Mh2= 455.144 kg/hr
mH2 = =455.444k/hr
Log P* = a – b/(c+Tdp) Assumption = PT = 1.5 bar = 1125 mmHg [(yacetone * pt )/(p*acetone * Tdp)] + [(yh2o * pt )/(p*water *Tdp)] + [(yipa * pt)/( pipa* * Tdp)] + [(yH2 *pt)/(pH2* * Tdp)]
=1
From Literature : For acetone A = 7.02447
B = 1161
C = 224
For H2O A = 7.96681 For IPA
B = 1668.21
C = 228
A = 8.3789 Using
B = 1788.02 yaceton = 0.6
C = 227.938
yH2o = 0.33
yipa = 0.07
Tdp = 94.7 0C
By trial error For aceton At 14.70C
&
1.5 bar
Cpacetone = 1.297 kg /K Qacetone== m * Cp * del T = 13151.6322 * 1.297 [(81+273.15) - (943.7 +273.15)] = - 233.690 * 10-6 kj Δ Hvep = Δ Hf [(Tc - T)/(Tc-Tb)]0.38 = 29140 kj/kmole Tc 508.1 K Δ Hvap
=
Tb= 341.5 K
=28289.029kj/kmole
=
For IPA At 94.70c & 1.5 bar Cpipa
=
1.761 kj / g KS
Cpipa = 1.761 kj.kg K Qipa = =1512.015 * 1.761 *(354.15-367.85) = -36.487 * 10^-3 Kj ∆ H vep =delHf [(Tc -T)/(Tc –Tb)]0.38 ∆HF = 39850 kj/kmole Tc =508.3K ∆Hvap = 4116935kg/kmole
Tb = 366.6K
487.07 kj/ kg
∆Hvap = 685128 kj/kg For H2O At 94.7 oC & 1.50bar CpH2o = 1.898 kj/kgK QH2o = 2232.293 *1898 *(354.15 -367.85) = -58.045 *10^3 kj ∆Hvap = 40683 kj/kmole Tc = 647.3 K
Tb = 385.106K
∆HVAP = 40683 * [(6473-354)/(6473-385.126)].38 = 42442.0561 kj/kmole =2356845 kj/lg For H2 At 94.70c & 1.5 bar CpH2 = 13.255 kj/kg K QH2
= 435.144 kg * 13225 * (354.15 – 367.85) = -82.464 * 103 kj
∑ m.Cp .∆ T = -410.677 *103 kg ∑mi ∆Hvap =12.702 * 106 kg QTOTAL = ∑mi CP,t ∆T + ∑mi . ∆Hvap = 12.3 *10^6
For H2O ∆T for water = (35-15)= 20 Cpwater =40182 kj/lg
Q = m*Cpwater *∆ T 682691.799kj = 40182 kj/kg * m *20 m=147.038 ton/day ∆H vap == 40683 *[(647.3 -354)/(647.3 -385.186)]0.38 =2356.845 kj/kgmole
7.3.7 For Scrubber: Qin = Qout Tref = 250C 455.144 * 14.419 *(81-25)+ 3528.708 *1.259*(81- 25) + 169.107 * 4.193 *(81-25) + 117.307 * 1.716 *(81-25) = 455.144 *14.401 *(70-25) + 3.485 *1229*(70-25) + 35.25.224 * 1249 *(T-25) + 27547.709 *4.183 *(T -25) + 117.307 * 1710 * (T-25) 4222.8319 = 18777.661 + (T-25)*755114.9 T = 28.10C
7.3.8 For Acetone column: ∆ Hvap = ∆Hf[(Tc -T)/(Tc- Tb)]0.38 Befor the application the boiling temp (Tb) for each of the component must be find at 1.1 bar pressur. For the boiling point calculation, ln psat = A - (B/T ) will be used Condenser: For Acetone - Pc= 47 bar
Tc= 508.1K P= 1.0133 bar T= 329.2K
ln1.0133= A-B/329.2
ln47= A-B/508.1
then A=10.91 B= 3587.3 At 1.1 bar pressure boiling point is- ln1.1= 10.91-(3587.3/Tb) Tb= 331.706K For ipa Pc=47.6 bar
Tc=508.3K
P= 1.0133 bar
T= 355.35K
ln1.0133= A-(B/355.35) ln47.6= A-(B/508.3)
A=12.807
B= 4546.375
At 1.1 bar pressure boiling point is ln1.1 = 12.807-(4546.375/ Tb)
Tb= 357.653K
Substituting the result to the first equation: ∆Hacetone= 29140*[(508.1-375.3) / (508.1-331.706) ]0.38 = 26160195 kj/ kmol ∆Hipa= 39858*[(508.3-375.3) / (508.3-357.653) ]0.38 ∆Hipa= 38014 kj/kmol For the mixture: ∆Hmix= 450.417*0.99+632.618*0.01 = 452.24 kj/kg MT=13263.045kg For the energy balance of the mixture: Q= mT*∆Hmix= 6*106 kj For Water: Pc= 220.5 bar
Tc= 647.3K P= 1.0133 bar T= 373.15K
ln1.0133= A-(B/373.15)
ln220.5= A-(B/647.3)
then A=12.72 B= 4743.39
At 1.1 bar pressure boiling point ln1.1= 12.72-(4743.39/Tb)
Tb=375.723K
Reboiler: ∆Hvap, aceton =29140 *[(508.1-378)/(508.1-331.706)]0.38 =25956.795 kj/kmole =446.951 kj/kg
FOR H2O ∆Hvap,H2O = 40683*[ (647.3-378)/(647.1-375.723)] 0.38 ∆Hvap, H2O = 40533.043kj/kgmole = 474.872 ∆Hvap, ipa = 39838 *[(508.3-378)/(508.3-337.653)]0.38 = 627.722 kj/kmole Yacetone = 4.364 * 10-4
yH2O = 0.955
∆H vap,mix= 446915 *6364 *10-4 + 674872 * 0.955 + 627.722*0.045 =672.945 kj/kg Balance; Q = mt . ∆ x vap mix = 30993.013*672.945 =20.86*106kj
7.3.9 IPA Column Tb ipa = 84.6530C
TbH2o = 102.7230C
yipa =0.045
∆Hf,H2o =40683kj/kmole
del Hf,ipa =39858kg/kmole
∆Hf,aceton = 29140 kj/kmole ∆Hvap,h2o =40294.194 kj/kmole= 2236.081kj/kg ∆Hvap,ipa = 38014 kj/kmole = 632.618kj/kg ∆Hvap,acetone = 26160.195 kj/kmole sience aceton is neglected YH2O = 0.13
Yipa = 0.87
∆Hvap,mix =2236.081*632.618 = 841.068 kj/kg For the energy balance for mixing Q = mT. ∆Hmix = 1941.326*841.068 =1.633 *106kj
Reboiler: ΔHvap, water = 40683 * [(647.3-384.5)/(647.1-375.723)]0.38 =40179.523 kj/kmole =2230.892kj/kg Q = mT.ΔH.vap,water = 2230.892*29407.290 = 65.604 *106kj
Preliminary equipment summary table for acetone process Equipment MOC POWER(Shaft) (KW) Efficiency
P-401 A/B P-402 A/B Carbon Steel Carbon steel 0.43 1.58 40%
_
_
_
32
20
1.90
_
_
3.30
_
_
_
0.80
0.75
_
_
2.40
2.25
_
_
Horizontal
Centrifugal/ Electric Op.Temreperatu 32 0 ( C) Pressure In 1.25 (bar) Pressure Out 3.10 (bar) Diameter(m) _
50%
V-402 Carbon steel _
_
Type/Drive
Height/Length (m) Orietionnt
V-401 Carbon steel _
Centifugal/ Electric 360
Intenals
_
_
_
Op. Pressure (bar) Maximum Allowable Op.Prs.(bar)
_
_
1.0
_
_
3.0
Horizontal SS Demister 1.63 3.2
Preliminary equipment summary table for acetone process (cont’d) Equipment MOC
T-401
H-401
Corban steel
Carbon steel
R-401 Carbon steel
Diameter
0.32
_
Width=4.57m
Height/Length(m)
3.20
_
Orientation
vertical
_
Depth=6.10m Height=5m Vertical
Internals
2.5m of packing (1”Ceremic Rashing Rings)
Op. Pressure (bar)
1.6
Maximum Allowable Op.prs.(bar)
3.2
Type Design Duty(Mj/h) Maximum Duty (Mj/h) Area Radiant (m2) Area Convectiv (m2)
_
3.0 Tube side 4.0
Fluidized bed Containing 7.5m3 of catalyst+7.8m3 of inert particle HTA=188m2 2.16 in bed 2.70 in tube 3.2 in bed 4.0 in bed
_
Fired heat
_
_
3436
3436
_
3800
_
_
13.0
_
_
37.0
_
Design Calculations Vertical Tube Vaporizer
Conditions Vapor leaves at 2.16 bar and 101C (saturated vapor). The shell side is assumed to be well mixed and at 101C. Heat Transfer Calculations 1. Regulate steam pressure to give a 10C temperature driving force T sat = 111C which corresponds to a P sat = 1.48 bar. 2. Heat Duty = 2850 MJ/h , Cpl = 2880 J/kgºC 3. Limiting heat transfer resistance is on boiling organic side, shell = 1000 W/m2 shell C. Uh shell = 1000 W/m2C Tln = T = 10C
A=Q/U•Tlm (F=1) = 285010 6 /3600/1000/10 = 79.2 m2
1110c 1010c T
Shell side well mixed
320c Lenth along tubes
Note: over the range of ∆T = 7 to 250c it is known that hT 1/3 for boiling isopropanol.
Reactor Heat Transfer Calculations Assume that the fluidized bed is well mixed, thus the feed gas immediately heats to the reactor temperature of 350C. The molten salt approach temperature is 10C and therefore the molten salt temperature leaving the reactor is 360C. The temperature vs. Q diagram is shown below:
Tin 3600c 3500c
3500c
1010c Length of reactor Q=3436 MJ/h Cp,gas = 1780 J/kgºC (inlet) and 2500 J/kgºC (outlet) Use Hi TecTM molten salt with the following average physical properties: C p = 1.72 kJ/kg K, = 1980 kg/m3, = 2.1 cP, Maximum operating temperature = 1000C Use a T = 50C for the circulating salt Tin = 410C Tlm= (410-360)/ln[(410-350)/(360-350)] = 27.9C
Energy balance on molten salt Q=MCpT 3436106 = (M)(1720)(50) M = 39,950 kg/h = 11.10 kg/s Vol flow of salt = M/ = 11.10/1980=5.60510-3 m3 /s Evaluation of U Fluidized Bed to tube wall, ho = 200 W/m2C [this will not change much with fluidization velocity in the range of 2 – 5 umf ] Inside heat transfer coefficient [molten salt to wall], h i = ? Assume that the velocity in the tubes is 2 ft/s = 0.61 m/s Use ½” diameter tube 18 BWG with inside diameter = 0.01021 m Re = (0.61)(0.01021)(1980)/(0.0021) =5872 Nu = 0.023Re 0.8 Pr 0.33 = (.023)(5872) 0.8 (17200.0021/0.606) 0.33 = 42.9 (actually Seider-Tate is only good for Re>10,000 - check this later) hi = Nu[k/d] = (42.9)(0.606)/(.01021) = 2546 W/m2C Below 500C molten salt should not foul so h f = very large Overall heat transfer coefficient, U = [d0/(dihi) + 1/ho]-1 = [1.244/2546+1/200]-1 = 182 W/m2C Heat transfer area, Ao = Q/Uo T lm = (343610)/[(3600)(182)(27.9)] = 188 m2
Check tube arrangement and molten salt velocity External surface area of 20 ft tubes =•doL = (3.142)(0.0127)(20)(0.3048) = 0.243 m2 Number of tubes = (188)/(0.243) = 773 Use 110 parallel sets of 7 tubes piped in series Cross sectional area (csa) for flow of molten salt = (110)(3.142)(0.01021)2/4 = 0.0090 m2 Velocity of molten salt in tubes = 5.60510-3/0.0090 = 0.622 m/s This gives Re = 5988 and Nu = 43.6 and hi = 2588 and U = 182 W/m 2C no change For Re<10,000 we should use correlation from Walas [1]: Nu0.012[Re 0.87 280]Pr 0.4 [1-(d/L)2/3] This gives Nu = 41.1 and h = 2438, thus U = 181 W/m 2 C same as before. Arrangement of tubes in Fluidized Bed
110 parallel banks of 7 tubes in Fluidized Bed Reactor
Height of Catalyst and Filler in Bed Use a square tube pitch of 1.5 inches Dimensions of tube bank are 1101.5/12 by 71.5/12 by 20 ft = 13.75 by 0.875 by 20 ft Assume bed width and depth of 15 by 20 ft respectively Volume of solids to just cover the tubes, assuming bottom row of tubes is 6” from distributor plate and 6” of solids above tube bank = Vsol V sol = (15)(20)(1+0.875) – volume occupied by tubes = 562.5 – (770)(20)(•)(0.5)2 /(4144) = 541.5 ft 2 = 15.3 m3 Calculate the amount of catalyst required for 90% conversion For a first order, isothermal, irreversible reaction at constant pressure we have the following expression for the conversion of component A,XA : Kτ = (1+ԑA)ln (1/1-XA)-ԑAXA From the kinetics expression, at a reactor temperature of 350C, we have: k=k0exp[-Ea/RT] =3.51×105exp[72,380/ (8.314)(273+350)] =0.2996m3gas/m3bulk catalyst ԑA= (number of mole if completely reacted – number of moles initially)/ number of moles initially = (96.48-57.84)/(57.84)=0.668 Using above values and 90% conversion we get: Kτ = (1+0.668)ln (1/1-0.9)-(0.668)(0.9)=3.2395 τ =(3.2395)/(0.2996) =10.813 m3bulk catalyst s/ m3gas
Vcatalyst =υgas τ Now the volumetric flow rate of gas, υgas =0.696 m3/s Vcatalyst = (0.696)(10.83) =7.5 m3bulk catalyst Amount of catalyst required is 7.5 m3, therefore we must add 7.8 m3 of inert filter to give a total of 15.3 m3 of bed solids. This will give a slumped bed height approximately 6 above the top of the tube bank. Check minimum fluidizing velocity Cross sectional area (csa) of bed = 300 ft2 = 27.9 m2 Properties of gas flowing through fluidized bed: = 1.067 kg/m3, = 18.210-6 kg/m.s flow of gas = 2670 kg/h vol flow of gas = (2670)/[(1.067)(3600)] = 0.696 m3 /s Superficial gas velocity, u = (0.696)/(27.9) = 0.0250 m/s catalyst particles are approximately 100 •m in diameter, and have a density of 2500 kg/m 3 and bulk density of 1200 kg/m3 . Calculate minimum fluidizing velocity using the correlation due to Wen and Yu [2] Repmf = [33.72 + 0.0408Ar]1/2-33.7 where Ar = dp3ρg(ρs-ρg)g/µ2 Ar = (10-4 )3 (1.067)(2500 – 1.067)(9.81)/(18.210-6 ) 2 = 78.97 Re pmf = [33.72 +0.0408(78.97)] 1/2– 33.7 = 0.0478 umf = (0.0478)(18.210-6 )/[(1.067)(10-4)] = 0.00815 m/s u/u mf = 0.0250/0.00815 = 3.06 O.K. Cyclones can handle solids and gas in the range 1< u/u mf <5
Pressure Drop Across Fluidized Bed Height of solids in fluidized bed = 1.875 ft = 0.57 m Pbed = =hbulkg = (0.57)(1200)(9.81) = 6727 Pa = 0.067 bar Distributor loss = 0.6 Pbed = 0.040 bar Internal cyclone losses = 0.14 bar (The design of the cyclones has been based on a maximum superficial gas velocity of 5umf ) Total loss across bed = 0.067 + 0.040 + 0.14 0.25 bar Use a reactor height of 5.0 m to accommodate solids bed, plenum, freeboard, and cyclones. Pressure Drop of Molten Salt through Heat Transfer Tubes Re for molten salt flow = 5988 Roughness of drawn tubes, e = 0.0015 mm e/d = 0.0015/10.21 = 0.00015 f = 0.0087 d = 0.01021 m = 1980 kg/m3 Leq = length of tube + equivalent length of 12-90 bends = (7)(20)(.3048) + (12)(30d) = 46.3m Pf = 2fLequ 2/d = (2)(1980)(0.0087)(46.3)(0.622) 2 /(0.01021) = 60443 Pa = 60.4 kPa
UTILITIES Utilities required for manufacturing acetone include electric power, potable and cooling water, and steam.
Electricity The power required for electrochemical processes; motor drives, lighting, and general use, may be generated on site, but will more usually be purchased from the local supply company (the national grid system in the UK). The economics of power generation on site are discussed by Caudle (1975). The voltage at which the supply is taken or generated will depend on the demand. For a large site the supply will be taken at a very high voltage, typically 11,000 or 33,000 V. Transformers will be used to step down the supply voltage to the voltages used on the site. In the United Kingdom a three-phase 415-V system is used for general industrial purposes, and 240-V single-phase for lighting and other low-power requirements. If a number of large motors is used, a supply at an intermediate high voltage will also be provided, typically 6000 or 11,000 V. A detailed account of the factors to be considered when designing electrical distribution systems for chemical process plants, and the equipment used (transformers, switch gearand cables), is given by Silverman (1964).
Water: Cooling water Natural and forced-draft cooling towers are generally used to provide the cooling water required on a site; unless water can be drawn from a convenient river or lake in sufficient quantity. Sea water, or brackish water, can be used at coastal sites, but if used directly will necessitate the use of more expensive materials of construction for heat exchangers Water for general use The water required for general purposes on a site will usually be taken from the local mains supply, unless a cheaper source of suitable quality water is available from a river, lake or well.
Demineralised water Demineralised water, from which all the minerals have been removed by ion-exchange, is used where pure water is needed for process use, and as boiler feed-water. Mixed and Multiple-bed ion-exchange units are used; one resin converting the cations to hydrogen and the other removing the acid radicals. Water with less than 1 part per million of dissolved solids can be produced. ANNUAL CONSUMPTION OF UTILITIES AND COST Description
Unit of
Qty.
Cost in '000 Birr
33,100
16
3
140
757
3
15,040
83
Measure Electricity
kWh
Furnace oil
m
Water
m
Total
856
Control and instrumentation Instrumentation is provided to monitor the key process variables during the plant operations. They may be incorporated in automatic control loops, or used for the manual monitoring of the process operation. They may also be part of an automatic computer data logging system. Instruments monitoring critical process variables will be fitted automatic alarms to alert the operations to critical and hazardous situation. It is desirable that the process variable to be monitored be measured directly ; often however, this is impractical and some dependent variables, i.e. easier to measure, is monitored in its place for example, in the control of the distillation columns the continuous , online analysis of the overhead product is desirable but difficult and expensive to achieve reliably, so temperature is often monitored as an indication of composition . The temperature instrument may form a part of a control loop controlling, say reflux flow; with the composition of the overhead checked frequently by sampling and laboratory analysis.
Instrumentation and Control Objectives The primary objectives of the designer when specifying instrumentation and control objectives are; 1. Safe Plant Operation:
To keep the process variables within known safe operating limits.
To detect dangerous situations as they develop and to provide alarms and automatic shutdown systems.
To provide interlocks and alarms to prevent dangerous operating procedures.
2. Production Rate: To achieve the design product output. 3. Product Qualities: To maintain the product composition within the specified quality standards. 4. Costs: To operate at the lowest production cost, commensurate with the other objectives. These are not separate objectives and must be considered together. The order in which they are listed is not mean to employ the precedence of any objective over another, other than that of putting safety first. Product quality, production rate and the cost of production will be dependent on sale requirement. For example, it may be better strategy to produce a better quality product at a higher cost in a typical chemical processing plant these objectives are achieved by a combination of automatic control , manual monitoring and laboratory analysis . Automatic Control System: The detail design and specification of the automatic control schemes for a large product is usually done by specialists. Guide Rule: The following procedure can be used when drawing up preliminary P&I DIAGRAM:
1. Identify and draw in those control loops that are obviously needed for steady state plant operation such as:
Level control
Flow control
Pressure control
Temperature control
2. Identify the key process variables that need to be controlled to be achieved the specified product quality. Include control loops using direct measurement of the controlled variable, where possible; if not practicable, select a suitable dependent variable. 3. Identify and include those additional control loops required for safe operation. 4. Decide and show those ancillary instruments needed for the monitoring of the plant operation by operators; and for trouble shooting and plant development .It is well worthwhile including additional connection for instruments which may be needed for future trouble shooting and plant development, even if the instruments are not installed permanently. This would include: extra thermo wells, pressure tapings, orifice flanges, and extra sample points. 5. Decide on the location of the sample points. 6. Decide on the need for recorders and the location of the read out points, local or control rooms. This step would be done in conjunctions with step 1 to 4. 7. Decide on the alarms and interlocks needed; this would be done in conjunction with step 3.
9.3 Typical Control System: Level Control: In any equipment where an interface exists between two phase (e.g. liquid –vapour), some means of maintaining the interface at required level must be provided.
This may be
incorporated in the design of the equipment. Figure shows a typical arrangement, as is usually done for the decanters by automatic control of the flow from the equipment.
Level control arrangement finds position at the base of column. The control valve should be placed on the discharge line from the pump. Pressure Control: Pressure control will be necessary for the most systems handling vapour of gas. The method of control will depend on the nature of the process. Typical schemes are proposed. When vented gas was toxic, or valuable. In these circumstances the vent should be taken to a vent recovery system, such as scrubber. Flow Control: Flow control is usually associated with inventory control in a storage tank or other equipment. There must be a reservoir to take up the charge ion flow rate. To provide flow control on a compressor or pump running at a fixed speed and supplying a near constant column output ,a by pass control would we used. Heat exchangers: In the simplest arrangement, the temperature being controlled by varying the flow of the cooling and heating medium. If the exchange is between two process streams whose flow are fixed, by-pass control will have to be used. Condenser Control: Temperature control is unlikely to be effective for condensers, unless the liquid streams are sub cooled. Pressure control is often used or control an be based on the outlet coolant temperature. Reboiler And Vaporizer: As with condensers, temperature control is not effective as the saturated vapour temperature is constant at constant pressure. Level control is often used for vaporizers ; the controller controlling the stream supply to the heating surface , with the liquid feed to vaporizer on flow control. An increase in the feed results in an automatic increases in stream to the vaporizer the increased flow and maintains the level constant.
Cascade Control: With this arrangement, the output of one controller is used to adjust the set point .cascade control can give smoother control in situation by direct control of the variable would lead to a unstable operation. The “Slave” controller can be used to compensate for any short –term variations in, say, a service. Stream flow, which would offset the controlled variable; the primary (master) controller long term variations. Ratio Control: Ratio control can be used for it is used where it is desired to maintain two flows at a constant ratio; for example, Reactor feeds and distillation column reflux. Distillation Column Control: The primary objective of distillation column control is to maintain the specified composition the top and bottom products, and any side streams; correcting for the effects of disturbances in: . Feed flow rate, composition and temperature. . Stream supply pressure . Cooling water pressure and heater temperatures. . Ambient composition, which cause changes in internal reflux. The compositions are controlled by regulating reflux flow and boil up. The column overall material balance must be controlled; distillation column has little surge capacity (hold up) and the flow of distillate and bottom product (and side streams). Must match the feed flows. A variety of control schemes has been devised for distillation column control. Column pressure is normally controlled at a constant value. The feed flow –rate is often set by the level controller on a preceding column. it can be independently controlled if the column is fed from a storage or surge tank. feed temperature is not normally controlled, unless a feed preheated is used. Temperature is often as an indication of composition. The temperature sensor should be located at the position in the column where the rate of change of temperature with change in composition of the key component is maximum. Near top and bottom of the column the change is usually small .with multicomponent systems, temperature is not unique function of the composition. Top temperature is usually controlled by varying the reflux ratio, the bottom temperature by varying the boil-up rate. If reliable on-line analyzers are variables they can be incorporated in the control loop, but more complex equipment will be needed. Differential pressure control is often used on packed columns to ensure the packing operates at the correct loading.
Addition temperature indication or recording points should be included up the column for monitoring column performance and for troubleshooting. Reactors Control: The schemes used for reactor control depend on the process and the type of reactor. If reliable on-line analyzer is available, and the reactor dynamics are suitable, the product composition can be Monitored continuously and the reactor conditions and feed flows controlled automatically to maintain the desired product composition and yield. Reactor temperature will normally be controlled by regulating the flow of heating or cooling medium. Pressure is usually held constant. Material balance control will be necessary to maintain the correct flow of reactants to the reactor and the flow of products and unreacted materials from reactor.
Alarms, Safety Trips and Interlocks Alarm: Alarms are used to alert operators of serious and potentially hazardous deviations in process conditions. Key instrument are filled with switches and relays to operate audible and visual alarms on the control panels and enunciators panels, where delay or lack of response, by the operator is likely to lead to the rapid development of a hazardous situations, the instrument would be fitted with a trip system to pumps, closing valves, operating emergency systems.
The basic components of the automatic control system are: 1. A sensor to monitor control variable and to provide an output signal when a preset value is exceeded. 2. A link to transfer the signal to the actuator, usually consisting of a system of pneumatic or electrical relays 3. An actuator to carry out the required action; close or open a valve, switch off a motor
Safety: A safety trip can be incorporated in a control loop. In this system, high temperature alarm operates a solenoid valve, releasing the air on the pneumatic activator, closing the valve on high temperature. However the safe operation of such a system will be dependent on the reliability of the control equipment, and for potentially hazardous situation it is better practice to specify a separate trip system. Provision must be made for the periodic checking of the trip system to ensure that the system operates when needed. Interlocks: Where it is necessary to follow a fixed sequence of operations for example, during a plant start-up and shut-down , or in batch operations interlocks are included to prevent operators, departing from the required sequence. They may be incorporated in the control system design as the pneumatic or electric relays, or may be mechanical interlocks. Special locks with various properties and key system are available. Computers and microprocessors an Process Control Computers are being increasingly used for data logging, process monitoring and control. They have largely superseded the strip charts and analog controllers seen in the older plants. The long instrument panels and “mimic” flow charts displays have been replaced by intelligent video displays units. These provide a window on the process. Operators and technical supervisors can call up and display any section of the process to review the operating parameters and adjust control settings. Abnormal and alarm situation are highlighted and displayed.
Historical operating data is retained in the computer memory. Averages and trends can be displayed, for plant investigation and trouble shooting.
Software to continuously update and optimize plant performance can be incorporated in the computer control systems. Programmable logic controllers (PLC‟s) are used for the control and interlocking of the processes where a sequential operating steps has to be carried out, such as in the batch processes and in the start-up and shut-down of the continuous process.
SAFETY DATA SHEET ACETONE 1. IDENTIFICATION OF THE SUBSTANCE/PREPARATION AND THE COMPANY: PRODUCT NAME: ACETONE CHEMICAL NAME 2 : PROPAN-2-ONE 2 HAZARDS IDENTIFICATION: Highly flammable. Irritating to eyes. Repeated exposure may cause skin dryness or Cracking. Vapours may cause drowsiness and dizziness. 3. FIRST AID MEASURES: GENERAL: IN ALL CASES OF DOUBT OR WHEN SYMPTOMS PERSIST, ALWAYS SEEK MEDICAL ATTENTION IN HALATION: Move affected person to fresh air. If recovery not rapid, seek medical attention. If breathing stops, provide artificial respiration. Keep affected person warm and at rest. IN GESTION: Only when conscious, rinse mouth with plenty of water and give plenty of water to drink - (approx 500ml). DO NOT INDUCE VOMITING. In case of spontaneous Vomiting, be sure that vomit can freely drain because of danger of suffocation. Keep patient at rest and obtain medical attention. SKIN: Remove contaminated clothing. Wash affected area with plenty of soap and water. Obtain medical attention. EYES: Rinse immediately with plenty of water for at least 5 minutes while lifting the eye lids. Seek medical attention. Continue to rinse. 4. FIRE FIGHTING MEASURES: EXTINGUISHING MEDIA: Water spray, fog or mist. Dry chemicals, sand, dolomite etc. Halon. Powder, foam or CO2. SPECIAL FIRE FIGHTING PROCEDURES: Move container from fire area if it can be done without risk. Take measures to retain water used for extinguishing. Do not release contaminated water into drains, soil and surface water. Dispose of contaminated water and soil according to local regulations.
UNUSUAL FIRE & EXPLOSION HAZARDS: Forms explosive mixtures with air. Extremely flammable. May explode in a fire. Vapour may travel considerable distance to source of ignition and flash back. HAZARDOUS COMBUSTION PRODUCTS: Burning may release oxides of carbon and other hazardous gases or vapours. PROTECTIVE MEASURES IN FIRE: Fire fighters should wear self-contained breathing apparatus. 6. ACCIDENTAL RELEASE MEASURES: PERSON AL PRECAUTION IN SPILL: Avoid direct contact with skin, eyes and clothing. Do not breathe vapour or fumes. PRECAUTIONS TO PROTECT ENVIRONMENT: Prevent contamination of soil, drains and surface water. SPILL CLEAN UP METHOD S: Accidental release measures - avoid ignition sources. Take-up spillage with absorbent, inert material and place in a suitable and closable labelled container for recovery or disposal. Wash the area clean with water and detergent, observing environmental requirements. Absorb small quantities with paper towels or other inert material and allow to evaporate in safe place (fume hood/cupboard). 7. HANDLING AND STORAGE: USAGE PRECAUTIONS: HANDLING - Product should be used in accordance with good industrial principles for handling and storing of hazardous chemicals. Avoid vapour inhalation, skin and eye contact. Do not use contact lenses. Avoid vapour formation and ignition sources. Ensure good ventilation and local exhaust extraction in work place. (engineering controls must be to explosion/flameproof standard). Earth container and transfer equipment to eliminate accumulation of static charge. STORAGE PRECAUTIONS: Avoid direct sunlight. Store in a cool, dry, well ventilated place, in securely closed original container. STORAGE CRITERIA: Flammable liquid storage. 8. EXPOSURE CONTROLS AND PERSONAL PROTECTION: INGREDIENT NAME: CAS No.: STD LT EXP 8 Hrs ST EXP 15 Min ACETONE 67-64-1 OES 750 ppm 1500 ppm
INGREDIENT COMMENTS: Refer to the current edition of HSE Guidance Note EH 40/200* for occupational exposure limits; VENTILATION: Work in fume cupboard. Respiratory protection required in insufficiently ventilated woking areas. RESPIRATORS: For short periods of work, a suitable RPE fitted with a combination charcoal or organic vapour cartridge is recommended. PROTECIVE GLOVES: Use impervious gloves made of butyl rubber of PTFE (teflon). EYE PROTECTION: Contact lenses should not be worn when working with this chemical! Where the potential for eye contact exists, splash-proof goggles or face shield must be worn. OTHER PROTECTION: Wear protective clothing and closed footwear. Wear personal protective equipment appropriate to the quantity of material handled. HYGIENIC WORK PRA CTIC ES: DO NOT SMOKE IN WORK AREA! SKIN PROTECTION - use appropriate barrier cream to prevent defatting and cracking of skin.
Safety Flammability The most common hazard associated with acetone is its extreme flammability. It auto-ignites at a temperature of 465 °C (869 °F). At temperatures greater than acetone's flash point of −20 °C (−4 °F), air mixtures of between 2.5% and 12.8% acetone, by volume, may explode or cause a flash fire. Vapors can flow along surfaces to distant ignition sources and flash back. Static discharge may also ignite acetone vapors. Health information Acetone has been studied extensively and is generally recognized to have low acute and chronic toxicity if ingested and/or inhaled. Inhalation of high concentrations (around 9200 ppm) in the air caused irritation of the throat in humans in as little as 5 minutes. Inhalation of concentrations of 1000 ppm caused irritation of the eyes and of the throat in less than 1 hour; however, the inhalation of 500 ppm of acetone in the air caused no symptoms of irritation in humans even after 2 hours of exposure. Acetone is not currently regarded as a carcinogen, a mutagenic chemical or a concern for chronic neurotoxicity effects. Acetone can be found as an ingredient in a variety of consumer products ranging from cosmetics to processed and unprocessed foods. Acetone has been rated as a GRAS (Generally Recognized as Safe) substance when present in beverages, baked foods, desserts, and preserves at concentrations ranging from 5 to 8 mg/L. Additionally, a joint U.S-European study found that acetone‟s "health hazards are slight. Toxicology Acetone is believed to exhibit only slight toxicity in normal use, and there is no strong evidence of chronic health effects if basic precautions are followed. At very high vapour concentrations, acetone is irritating and, like many other solvents, may depress the central nervous system. It is also a severe irritant on contact with eyes, and a potential pulmonary aspiration risk. In one documented case, ingestion of a substantial amount of acetone led to systemic toxicity, although the patient eventually fully recovered.
Some sources estimate LD50 for human ingestion at 1.159 g/kg; LD50 inhalation by mice is given as 44 g/m3, over 4 hours. Acetone has been shown to have anticonvulsant effects in animal models of epilepsy, in the absence of toxicity, when administered in mill molar concentrations. It has been hypothesized that the high-fat low-carbohydrate ketogenic diet used clinically to control drug-resistant epilepsy in children works by elevating acetone in the brain.
EPA EPCRA Delisting (1995). EPA removed acetone from the list of “toxic chemicals” maintained under Section 313 of the Emergency Planning and Community Right to Know Act (EPCRA). In making that decision, EPA conducted an extensive review of the available toxicity data on acetone and found that acetone “exhibits acute toxicity only at levels that greatly exceed releases and resultant exposures,” and further that acetone “exhibits low toxicity in chronic studies.”
Genotoxicity. Acetone has been tested in more than two dozen in vitro and in vivo assays. These studies indicate that acetone is not genotoxic.
Carcinogenicity. EPA in 1995 concluded, “There is currently no evidence to suggest a concern for carcinogenicity.”(EPCRA Review, described in Section 3.3). NTP scientists have recommended against chronic toxicity/carcinogenicity testing of acetone because “the prechronic studies only demonstrated a very mild toxic response at very high doses in rodents.”
Neurotoxicity and Developmental Neurotoxicity. The neurotoxic potential of both acetone and isopropanol, the metabolic precursor of acetone, have been extensively studied. These studies demonstrate that although exposure to high doses of acetone may cause transient central nervous system effects, acetone is not a neurotoxicant. A guideline developmental neurotoxicity study has been conducted with isopropanol, and no developmental neurotoxic effects were identified, even at the highest dose tested.
Environmental. When the EPA exempted acetone from regulation as a volatile organic compound (VOC) in 1995, EPA stated that this exemption would “contribute to the achievement of several important environmental goals and would support EPA‟s pollution prevention efforts.” 60 Fed. Reg. 31,634 (June 16, 1995). 60 Fed. Reg. 31,634 (June 16, 1995). EPA noted that acetone could be used “as a substitute
for several compounds that are listed as hazardous air pollutants (HAP) under section 112 of the [Clean Air] Act. Environmental effects Acetone evaporates rapidly, even from water and soil. Once in the atmosphere, it is degraded by UV light with a 22-day half-life. Acetone dissipates slowly in soil, animals, or waterways since it is sometimes consumed by microorganisms, but it is a significant groundwater contaminant due to its high solubility in water. The LD50 of acetone for fish is 8.3 g/l of water (or about 0.8%) over 96 hours, and its environmental half-life is about 1 to 10 days. Acetone may pose a significant risk of oxygen depletion in aquatic systems due to the microbial activity consuming it. Acetone peroxide When oxidized, acetone forms acetone peroxide as a by-product, which is a highly unstable compound. It may be formed accidentally, e.g. when waste hydrogen peroxide is poured into waste solvent containing acetone. Acetone peroxide is more than ten times as sensitive to friction and shock as nitro-glycerine. Due to its instability, it is rarely used, despite its easy chemical synthesis Potential Health Effects
Inhalations Inhalation of vapors irritates the respiratory tract. May cause coughing, dizziness, dullness, and headache. Higher concentrations can produce central nervous system depression, narcosis, and unconsciousness. Ingestion: Swallowing small amounts is not likely to produce harmful effects. Ingestion of larger amounts may produce abdominal pain, nausea and vomiting. Aspiration into lungs can produce severe lung damage and is a medical emergency. Other symptoms are expected to parallel inhalation.
Skin Contact: Irritating due toe defatting action on skin. Causes redness, pain, drying, and cracking of the skin. Eye Contact: Vapors are irritating to the eyes. Splashes may cause severe irritation, with stinging, tearing, redness and pain. Chronic Exposure: Prolonged or repeated skin contact may produce severe irritation or dermatitis. Aggravation of Pre-existing conditions Use of alcoholic beverages toxic effects. Exposure may increase the toxic protentian of chlorinated hydrocarbons, such as chloroform, trichloroethane First Aid Measures Inhalation Remove to fresh air. If not breathing, give artificial respiration. If breathing is difficult, give oxygen. Get medical attention. Ingestion Aspiration hazard. If swallowed, vomiting may occur spontaneously, but DO NOT INDUCE. If vomiting occurs, keep head below hips to prevent aspiration into lungs. Never give anything by mouth to an unconscious person. Call a physician immediately. Skin Contact Immediately flush skin with plenty of water for at least 15 minutes. Remove contaminated clothing and shoes. Get medical attention. Wash clothing before reuse. Thoroughly clean shoes before reuse. Eye Contact Immediately flush eyes with plenty of water for at least 15 minutes, lifting upper and lower eyelids occasionally. Get medical attention.
Fire Fighting Measures Fire Flash point: -20oC (-4F) CC Auto ignition temperature: 465oC (869 F) Flammable limits in air % by volume: Lel : 2,5; uel : 12,8 Extremely flammable liquid and vapor! vapor may cause flash fire
Explosion Above flash point, vapor-air mixtures are explosive within flammable limits noted above. Vapors can flow along surfaces to distant ignition source and flash back. Contact with string oxidizer may cause fire. Sealed containers may rupture when heated. This material may produce a floating fire hazard. Sensitive to static discharge. Fire Extinguishing Media Dry chemical, alcohol foam or carbon dioxide. Water may be ineffective. Water spray may be used to keep fire exposed containers cool, dilute spills to nonflammable mixtures, protect personnel attempting to stop leak and disperse vapors. Special information In the event of a fore, wear full protective clothing, such as breathing apparatus with full face piece operated in the pressure demand or other positive pressure mode. Handling and Storage Protect against physical damage. Store in a cool, dry well-ventilated location, away from any area where the fire hazard may be a cute. Outside or detached stroge s preferred. Separate from incompatibles. Containers should be bonded and grounded for transfers to avoid static sparks. Storage and use areas should be NO SMOKING AREA. Use non-sparking type tools and equipment, including explosion proof ventilation. Containers of this material may be
hazardous when empty since they retain product residues (vapors, liquid); observe all warning and precautions listed for the product. Exposure Controls/Personal Protection Ventilation system A system of local and/or general exhaust is recommended to keep employee exposures below the airborne exposure limits. Local exhaust ventilation is generally preferred because it can control the emissions of the contaminant at its source, preventing dispersion of it into the general work area. Personal respirators If the exposure limit is exceeded and engineering controls are not feasible, a half-face organic vapor respirator may be worn up to ten times the exposure limit, or the maximum use concentration specified by the appropriate regulatory agency or respirator supplier, whichever is lowest. A full face-piece organic vapor respirator may be worn up to 50 times the exposure limit, or the maximum use concentration specified by the appropriate regulatory agency or respirator supplier, whichever is lowest. For emergencies or instances where the exposure levels are not known, use a full-face piece positive-pressure, air-supplied respirator. WARNING: air-purifying respirators do not protect workers in oxygen-deficient atmospheres Skin Protection Wear impervious protective clothing, including boots, gloves, lab coat, apron or coveralls, as appropriate, to prevent skin contact. Eye contact Use chemical safety goggles and/or a full face shield where splashing is possible. Maintain eye wash fountain and quick-drench facilities in work area. Stability and Reactivity Stability Stable under ordinary conditions of use and storage.
Hazardous Decomposition Products: Carbon dioxide and carbon monoxide may form when heated to decomposition. Hazardous Polymerization: Will not occur. Incompatibilities: Concentrated nitric and sulfuric acid mixtures, oxidizing materials, chloroform, alkalis, chlorine compounds, acids, potassium t-butoxide. Conditions to Avoid: Heat, flames, ignition sources and incompatibles
PLANT LOCATION The geographical location of the final plant can have strong influence on the success of an industrial venture. Considerable care must be exercised in selecting the plant site, and many different factors must be considered. Primarily, the plant should be located where the minimum cost of production and distribution can be obtained, but other factors, such as room for expansion and safe living conditions for plant operation as well as the surrounding community, are also important. A general consensus as to the plant location should be obtained before a design project reaches the detailed estimate stage, and a firm location should be established upon completion of the detailed-estimate design. The choice of the final site should first be based on a complete survey of the advantages and disadvantages of various geographical areas and, ultimately, on the advantages and disadvantages of available real estate. The following factors should be considered in selecting a plant site: 1. Raw materials availability 2. Markets 3. Energy availability 4. Climate 5. Transportation facilities 6. Water supply 7. Waste disposal 8. Labor supply 9. Taxation and legal restrictions 10. Site characteristics 11. Flood and fire protection. 12. Community factors PLANT DESIGN AND ECONOMICS FOR CHEMICAL ENGINEERS The factors that must be evaluated in a plant-location study indicate the need for a vast amount of information, both quantitative (statistical) and qualitative. Fortunately, a large number of agencies, public and private, publish useful information of this type greatly reducing the actual original gathering of the data.
Raw materials availability. The source of raw materials is one of the most important factors influencing the selection of a plant site. This is particularly true if large volumes of raw materials are consumed, because location near the raw-materials source permits considerable reduction in transportation and storage charges. Attention should be given to the purchased price of the raw materials, distance from the source of supply, freight or transportation expenses, availability and reliability of supply, purity of the raw materials, and storage requirements. Markets The location of markets or intermediate distribution centers affects the cost of product distribution and the time required for shipping. Proximity to the major markets is an important consideration in the selection of a plant site, because the buyer usually finds it advantageous to purchase from nearby sources. It should be noted that markets are needed for by-products as well as for major final products. Energy availability Power and steam requirements are high in most industrial plants, and fuel is ordinarily required to supply these utilities. Consequently, power and fuel can be combined as one major factor in the choice of a plant site. Electrolytic processes require a cheap source of electricity, and plants using electrolytic processes are often located near large hydroelectric installations. If the plant requires large quantities of coal or oil, location near a source of fuel supply may be essential for economic operation. The local cost of power can help determine whether power should be purchased or self-generated. Climate If the plant is located in a cold climate, costs may be increased by the necessity for construction of protective shelters around the process equipment, and special cooling towers or air-conditioning equipment may be required if the prevailing temperatures are high. Excessive humidity or extremes of hot or cold weather can have a serious effect on the economic operation of a plant, and these factors should be examined when selecting a plant site. Transportation facilities Water, railroads, and highways are the common means of transportation used by major industrial concerns. The kind and amount of products and raw materials determine the most suitable type of transportation facilities. In any case, careful attention should be given to local freight rates and existing railroad lines. The proximity to railroad centers and the possibility of canal, river, lake, or ocean transport must be considered: Motor trucking.
GENERAL DESIGN CONSIDERATIONS facilities are widely used and can serve as a useful supplement to rail and water facilities. If possible, the plant site should have access to all three types of transportation, and, certainly, at least two types should be available. There is usually need for convenient air and rail transportation facilities between the plant and the main company headquarters, and effective transportation facilities for the plant personnel are necessary. Water supply The process industries use large quantities of water for cooling, washing, steam generation, and as a raw material. The plant, therefore, must be located where a dependable supply of water is available. A large river or lake is preferable, although deep wells or artesian wells may be satisfactory if the amount of water required is not too great. The level of the existing water table can be checked by consulting the state geological survey, and information on the constancy of the water table and the year-round capacity of local rivers or lakes should be obtained. If the water supply shows seasonal fluctuations, it may be desirable to construct a reservoir or to drill several standby wells. The temperature, mineral content, silt or sand content, bacteriological content, and cost for supply and purification treatment must also be considered when choosing a water supply. Waste disposal In recent years, many legal restrictions have been placed on the methods for disposing of waste materials from the process industries. The site selected for a plant should have adequate capacity and facilities for correct waste disposal. Even though a given area has minimal restrictions on pollution, it should not be assumed that this condition will continue to exist. In choosing a plant site, the permissible tolerance levels for various methods of waste disposal should be considered carefully, and attention should be given to potential requirements for additional waste-treatment facilities. Labor supply The type and supply of labor available in the vicinity of a proposed plant site must be examined. Consideration should be given to prevailing pay scales, restrictions on number of hours worked per week, competing industries that can cause dissatisfaction or high turnover rates among the workers, and variations in the skill and productivity of the workers.
Taxation and legal restrictions State and local tax rates on property income, unemployment insurance, and similar items vary from one location to another. Similarly, local regulations on zoning, building codes, nuisance aspects, and transportation facilities can have a major influence on the final choice of a plant site. In fact, zoning difficulties and obtaining the many required permits can often be much more important in terms of cost and time delays than many of the factors discussed in the preceding sections. Site characteristics The characteristics of the land at a proposed plant site should be examined carefully. The topography of the tract of land and‟ the soil
PLANT DESIGN AND ECONOMICS FOR CHEMICAL ENGINEERS structure must be considered, since either or both may have a pronounced effect on construction costs. The cost of the land is important, as well as local building costs and living conditions. Future changes may make it desirable or necessary to expand the plant facilities. Therefore, even though no immediate expansion is planned, a new plant should be constructed at a location where additional space is available. Flood and fire protection Many industrial plants are located along rivers or near large bodies of water, and there are risks of flood or hurricane damage. Before selecting a plant site, the regional history of natural events of this type should be examined and the consequences of such occurrences considered. Protection from losses by fire is another important factor in selecting a plant location. In case of a major fire, assistance from outside fire departments should be available. Fire hazards in the immediate area surrounding the plant site must not be overlooked.
Community factors The character and facilities of a community can have quite an effect on the location of the plant. If a certain minimum number of facilities for satisfactory living of plant personnel do not exist, it often becomes a burden for the plant to subsidize such facilities. Cultural facilities of the community are important to sound growth. Churches, libraries, schools, civic theaters, concert associations, and other similar groups, if active and dynamic, do much to make a community progressive. The problem of recreation deserves special consideration. The efficiency, character, and history of both state and local government should be evaluated.
The existence of low taxes is not in itself a favorable situation unless the community is already well developed and relatively free of debt. Selection of the Plant Site The major factors in the selection of most plant sites are (1) raw materials, (2) markets, (3) energy supply, (4) climate, (5) transportation facilities, and (6) water supply. For a preliminary survey, the first four factors should be considered. Thus, on the basis of raw materials, markets, energy supply, and climate, acceptable locations can usually be reduced to one or two general geographical regions. For example, a preliminary survey might indicate that the best location for a particular plant would be in the south-central or south-eastern part of the United States. In the next step, the effects of transportation facilities and water supply are taken into account. This permits reduction of the possible plant location to several general target areas. These areas can then be reduced further by considering all the factors that have an influence on plant location. As a final step, a detailed analysis of the remaining sites can be made. Exact data on items such as freight rates, labor conditions, tax rates, price of land, and general local conditions can be obtained. The various sites can be
GENERAL DESIGN CONSIDERATIONS Inspected and appraised on the basis of all the factors influencing the final decision. Many times, the advantages of locating a new plant on land or near other facilities already owned by the concern that is building the new plant outweigh the disadvantages of the particular location. In any case, however, the final decision on selecting the plant site should take into consideration all the factors that can affect the ultimate success of the overall operation.
PLANT LAYOUT After the process flow diagrams are completed and before detailed piping, structural, and electrical design can begin, the layout of process units in a plantand the equipment within these process units must be planned. This layout can play an important part in determining construction and manufacturing costs, and thus must be planned carefully with attention being given to future problems that may arise. Since each plant differs in many ways and no two plant sites are exactly alike, there is no one ideal plant layout. However, proper layout in each case will include arrangement of processing areas, storage areas, and handling areas in efficient coordination and with regard to such factors as:
1. New site development or addition to previously developed site
2. Type and quantity of products to be produced 3. Type of process and product control 4. Operational convenience and accessibility 5. Economic distribution of utilities and services 6. Type of buildings and building-code requirements 7. Health and safety considerations 8. Waste-disposal requirements 9. Auxiliary equipment 10. Space available and space required 11. Roads and railroads 12. Possible future expansion Preparation of the Layout Scale drawings, complete with elevation indications can be used for determining the best location for equipment and facilities. Elementary layouts are developed first. These show the fundamental relationships between storage space and operating equipment. The next step requires consideration of the safe operational sequence and gives a primary layout based on the flow of materials, unit operations, storage, and future expansion. By analyzing all the factors that are involved in plant layout, a detailed recommendation can be presented, and drawings and elevations, including isometric drawings of the piping systems, can be prepared.
FINANCIAL ANALYSIS The financial analysis of the acetone project is based on the data presented in the previous chapters and the following assumptions:Construction period
1 year
Source of finance
30 % equity 70 % loan
Tax holidays
3 years
Bank interest
8%
Discount cash flow
8.5%
Accounts receivable
30 days
Raw material local
30 days
Raw material, import
90 days
Work in progress
5 days
Finished products
30 days
Cash in hand
5 days
Accounts payable
30 days
A. TOTAL INITIAL INVESTMENT COST The total investment cost of the project including working capital is estimated at Birr 6.17 million, of which 27 per cent will be required in foreign currency. The major breakdown of the total initial investment cost is shown in Table 7.1. Table 7.1 INITIAL INVESTMENT COST Sr
Total Cost („000
Cost Items
No.
Birr)
1
Land lease value
700.0
2
Building and Civil Work
1,500.0
3
Plant
Machinery
and 2,841.2
Equipment 4
Office
Furniture
and 100.0
Equipment 5
Vehicle
250.0
6
Pre-production Expenditure*
440.9
7
Working Capital
342.0
Total Investment cost
6,174.2
Foreign Share
27
PRODUCTION COST The annual production cost at full operation capacity is estimated at Birr 3.29 million (see Table 7.2). The material and utility cost accounts for 65.16 per cent, while repair and maintenance take 3.45 per cent of the production cost. ANNUAL PRODUCTION COST AT FULL CAPACITY ('000 BIRR) Items
Cost
%
Raw Material and Inputs
1,288.26
39.15
Utilities
856
26.01
Maintenance and repair
113.65
3.45
Labour direct
147.24
4.47
Factory overheads
49.08
1.49
Administration Costs
98.16
2.98
Total Operating Costs
2,552.39
77.57
Depreciation
484.12
14.71
Cost of Finance
254.09
7.72
Total Production Cost
3,290.60
100
FINANCIAL EVALUATION 1. Profitability According to the projected income statement, the project will start generating profit in the first year of operation. Important ratios such as profit to total sales, net profit to equity (Return on equity) and net profit plus interest on total investment (return on total investment) show an increasing trend during the life-time of the project. The income statement and the other indicators of profitability show that the project is viable. Break-even Analysis The break-even point of the project including cost of finance when it starts to operate at full capacity (year 3) is estimated by using income statement projection. BE =
Fixed Cost / (Sales-Variable Cost)
= 24 %
3. Pay Back Period The investment cost and income statement projection are used to project the pay-back period. The project‟s initial investment will be fully recovered within 6 years. 4. Internal Rate of Return and Net Present Value Based on the cash flow statement, the calculated IRR of the project is 14 % and the net present value at 8.5% discount rate is Birr 1.71 million. D. ECONOMIC BENEFITS The project can create employment for 20 persons. In addition to supply of the domestic needs, the project will generate Birr1.2 million in terms of tax revenue. The establishment of such factory will have a foreign exchange saving effect to the country by substituting the current imports.
Equipment Heat Exchanger (E-401): This unit heats, vaporizes, and superheats the feed to 235°C at 2.2 bar. A pump, which is not shown and which you do not have to be concerned with this semester, increases the pressure of the feed to the indicated pressure. Reactor (R-401): Following development of a new catalyst, only the following reaction occurs:
CH 3CHOHCH3 CH 3COCH 3 H 2 IPA
acetone
The reaction occurs at 350°C, and the conversion at this temperature is 90%. The reactor exit pressure is 1.9 bar. The reaction is endothermic with heat being supplied by hot molten salt. Fired Heater (H-401): This unit heats the molten salt that provides heat to the reactor. Energy is supplied by combustion of natural gas, which may be assumed to be pure methane. The molten salt enters the fired heater at 360°C (Stream 3) and leaves the fired heater at 410°C (Stream 4). The heat capacity of molten salt is 1.56 J/g K.
(1)
Heat Exchanger (E-402): This unit cools and partially condenses the reactor effluent. None of the hydrogen condenses. The exit pressure may be at any pressure below 1.6 bar and any temperature below 50°C that can be achieved by using cooling water (cw) or refrigerated water (rw) is possible. Separation Vessel (V-401): This unit disengages the vapor and liquid effluent from E-402. In this separator, all hydrogen in the feed enters the vapor phase, Stream 7. All other components distribute according to Raoult‟s Law at the temperature and pressure of E-402. The combination of E-402 and V401 is often called a flash operation.
Absorber (T-401): Here, additional acetone is recovered by absorption into pure process water. The absorber operates at the same temperature and pressure as V-401 Stream 11 contains all of the hydrogen and the acetone and water which are not in Stream 10. Stream 10 contains all of the IPA in Stream 7, 95% of the water in Streams 7 and 9. The amount of acetone in Stream 10 can be calculated from:
ystream 11 ystream 7
1 A 1 A6
(2)
Where y is the mole fraction of acetone,
A
L mV
(3)
L is the total molar flowrate of liquid in Stream 9, and V is the total molar flowrate of liquid in Stream 7. The parameter m is an equilibrium constant that is a function of temperature and pressure
3598 exp10.92 T m P
where T is in Kelvin and P is in atm.
(4)
Distillation Column (T-402): In this distillation column, the acetone, IPA, and water in Stream 12 are separated. The column operates at 1.4 bar. Specifications are as follows. The acetone must be 99.9 mol% pure and 99.5 mol% of the acetone in the feed must be recovered in Stream 13. Stream 14 contains most of the water and IPA from Stream 12.
Heat Exchanger (E-403): In this heat exchanger, the contents of Stream 13 are condensed from saturated vapor to saturated liquid at a rate three times the flow of Stream 13. The cost is for the amount of cooling water needed to remove the necessary energy. Heat Exchanger (E-404): In this heat exchanger, you may assume that one-half of the flow of Stream 14 is vaporized from saturated liquid to saturated vapor at 1.4 bar and is returned to the column. The cost is for the amount of low-pressure steam needed to supply the necessary heat. An additional distillation column (T-403): You may choose to add an additional distillation column to process Stream 14 further. This column can recover a near azeotropic mixture of water and IPA (88 wt% IPA – with all of the acetone remaining in Stream 14) out of the top, with residual water and IPA out the bottom. If you choose to do this, you must recycle the IPA/water top product to the beginning of the process. The bottom product goes to waste water treatment. This distillation column needs two heat exchangers with similar energy specifications to E-403 and E-404. This distillation column operates at 1.2 bar. You should only include this column if you decide it to be economically attractive Other Equipment It is required for two streams that mix to be at identical pressures. Pressure reduction may be accomplished by adding a valve. These valves are not shown on the attached flowsheet, and it may be assumed that additional valves can be added as needed at no cost. Flow occurs from higher pressure to lower pressure. Pumps increase the pressure of liquid streams, and compressors increase the pressure of gas streams. You may assume that a pump exists where ever you need one. For this semester only, there is no cost for pumps.
Equipment Costs
The equipment costs for the acetone plant are given below. Each cost is for an individual piece of equipment, including installation.
Equipment
Installed Cost in millions of $
Reactor, R-401
1.5
Absorber, T-401
0.03
Acetone distillation column T402
2.8
including condenser
reboiler
and
IPA distillation column T-403 (if added) including condenser
reboiler
and
Vessel, V-401
0.07
Any heat exchanger
0.05
Fired heater installed cost in dollars: 11 10 x
where x 2.5 0.8 log10 Q
where Q is the heat duty in kW
Utility Costs
0.1
Low-Pressure Steam (446 kPa, saturated)
$5.00/1000 kg
Medium-Pressure Steam (1135 kPa, saturated)
$7.31/1000 kg
High-Pressure Steam (4237 kPa, saturated)
$8.65/1000 kg
Natural Gas or Fuel Gas (446 kPa, 25C)
$3.00/GJ
Electricity
$0.05/kW h
Boiler Feed Water (at 549 kPa, 90C)
$2.54/1000 kg
Cooling Water
$0.16/GJ
available at 516 kPa and 30C return pressure 308 kPa return temperature should be no more than 15C above the inlet temperature
Refrigerated Water
$1.60/GJ
available at 516 kPa and 10C return pressure 308 kPa return temperature is no higher than 20C
Process Water available at 300 kPa and 25°C
Data
$0.04/1000 kg
Use data from Reference [1] or from any handbook (such as Reference [2]). The following data are not readily available in these references. Liquid Heat Capacity For IPA: 145 J/mole K Vapor Heat Capacity for IPA: 27.87 + 0.176 + 2.1210-4T 2 - 4.0910-7T 3 J/mole K T (K) Vapor Pressures – Antoine‟s Equation constants
ln p* A
B T C
(5)
(p* in mm Hg, T in K) A
B
C
IPA
17.664
3109.3
-73.546
acetone
16.732
2975.9
-34.523
Normal heat of vaporization for IPA: 56,900 kJ/kmole
Economic Analysis
When evaluating alternative cases, the following objective function should be used. It is the equivalent annual operating cost (EAOC), and is defined as EAOC = -(product value - feed cost - other operating costs - capital cost annuity) A negative EAOC means there is a profit. It is desirable to minimize the EAOC; i.e., a large negative EAOC is very desirable. The cost for acetone is $0.88/kg. The cost for IPA is $0.72/kg IPA in the feed solution. The value for hydrogen is $35/1000 std m3. Other operating costs are utilities, such as steam, cooling water, natural gas, and electricity. The capital cost annuity is an annual cost (like a car payment) associated with the one-time, fixed cost of plant construction. A list of capital costs for all pieces of equipment will be provided by early March. The capital cost annuity is defined as follows: Capital cost annuity = 0.2(capital cost)
Cost Data
Raw Materials Isopropanol (88 – 91 wt%)
see Chemical Marketing Reporter
Utility Costs Low Pressure Steam (618 kPa saturated)
$6.62/1000 kg
Medium Pressure Steam (1135 kPa saturated)
$7.31/1000 kg
High Pressure Steam (4237 kPa saturated)
$8.65/1000 kg
Natural Gas (446 kPa, 25C)
$3.00/GJ
Fuel Gas (use this price for fuel gas credit)
$2.75/GJ
Electricity
$0.06/kW h
Boiler Feed Water (at 549 kPa, 90C)
$2.54/1000 kg
Cooling Water available at 516 kPa and 30C
$0.16/GJ
return pressure 308 kPa return temperature is no more than 15C above the inlet temperature. Refrigerated Water available at 516 kPa and 10C
$1.60/GJ
return pressure 308 kPa return temperature is no higher than 20C. Deionized Water available at 5 bar and 30°C Waste Treatment of Off-Gasincinerated -
Equipment Costs (Purchased)
$1.00/1000 kg incinerated-take fuel credit
Piping
$/m = 5.0 (diameter, in)
Valves double the price
$100 (flow diameter, in) 0.8 for control valve with orifice plate,
Pumps
$630 (power, kW) 0.4
Heat Exchangers
$1030 (area, m 2 ) 0.6 add 25% additional for boilers or evaporators
Compressors efficiency
$770 (power, kW) 0.96 + $400 (power, kW) 0.6 assume 70%
Turbine
$2.18•10 5 (power output, MW) 0.6 assume 65% efficiency
Fired Heater $635 (duty, kW) 0.8 assume 80% thermal efficiency assume can be designed to use any organic compound as a fuel Vessels $[1.67(0.959 + 0.041P - 8.3•10-6 P 2 )]•10 z z = (3.17 + 0.2D + 0.5 log 10 L + 0.21 log 10 L) D = diameter, m 0.3 m < D < 4.0 m L = height, m 3 < L/D < 20 P = absolute pressure, bar Reactor
Equipment Cost Factor:
assume to be $1 million
Pressure Factors Pressure
<10 atm,0.0
Does not apply to turbines,
(absolute)
10-20 atm,0.6
compressor,vessels,packing 20-40 atm,3.0 their
trays or catalysts, since
40-50 atm,5.0
cost equations
includepressure 50-100 atm,10
effects.
Material factors Carbon steel -0.0 Stainless steel- 4.0 Total installed cost=Purchased cost(4+material factor+pressure factor ) Heat Exchangers: For heat exchangers that do not have to be designed in detail, use the following approximation for heat transfer coefficients to allow you to determine the heat transfer area and heat exchanger cost. SITUATION
h(w/m2c 0)
Condensing Steam
6000
Condensing Organic
1000
Boiling Water
7500
Boiling Organic
1000
Flowing Liquid
600
Flowing Gas
60
