1
1.INTRODUCTION
Isopropyl alcohol (IPA) with its excellent properties is a growing-demand product worldwide. Common names for it include IPA, rubbing alcohol, dimethyl carbinol, isopropanol, 2-propanol and sec-propyl alcohol. IPA (C3H7OH) is a flammable, colorless liquid with a strong and slightly pleasant odor. It is completely miscible with water, ethanol, acetone, chloroform, and benzene; melting at -89 C and boiling at 82 C. It has an advantage of being soluble in non polar substances and evaporating quickly. Therefore, it is commonly used as either a solvent or a cleaning fluid.It is very inexpensive and cost effective which contributes to its widespread usage.[6][7]
In today’s society IPA has many practical uses from paint thinner to rubbing alcohol and has extensive applications in pharmaceutical, pesticide, coatings, daily-use chemical and organic synthesis sectors. The primary usage for IPA is as an industrial solvent for many oils, alkaloids, gums and resins,but it has many more usages. In the stores, rubbing alcohol generally consisting of 70% isopropanol is sold in order to be used for a variety of uses such as cleaning, sterilizing skin or helping to get rid of swimmers ear. As a cleaning agents IPA is used on electronics devices such as contact pins (like those on ROM cartridges), magnetic tape deck and floppy disk drive heads, the lenses of lasers in optical disc drives (e.g. CD, DVD) and removing thermal paste from CPU's. It is also used to clean glass computer monitor screens, and is used by many music shops to give second-hand or worn records newer looking sheens. It cleans dry-erase boards very well and other unwanted ink related marks. In biology isopropanol can be used in a strong solution as a preservative to replace formaldehyde. Another common use for IPA is as an additive in gasoline so that fuel lines don’t freeze in the winter.It is also used in manufacturing acetone, glycerol and isopropyl acetate. [7]
On the other side toxicology is a matter fact to be considered for human health. There is no risk of cancer, risk of malformation in an unborn fetus or risk of heritable genetic effects. But, skin contact over a long period of time may cause dermatitis. Therefore, body care products including IPA are not adviced with respect to a clinical research.[8][9]
The total capacity of isopropyl alcohol is around 2.3 million t/a in the world, 37% in the United States, 4% in Canada, 3% in Latin America, 38% in West Europe, 8% in Japan and 10% in the Asian-Pacific Region. The United States, Japan and West Europe are also major consumers in the world and the consumption accounts for 70% of the world total. In these countries and regions isopropyl alcohol is mainly used as solvent and in acetone processing and the consumption in these two fields’ accounts for 60 - 70% of the total. In terms of isopropyl alcohol derivatives, the demand in cleaning agents is making the most rapid growth and the consumption in chemical intermediates is also having a rapid increase. The demand in pharmaceuticals, surfactants and inks has been stable in the recent years and the demand in coatings and pesticides has presented a declining trend.[10]
There are three commercial routes to IPA are used. The indirect hydration of refinery-grade propylene uses sulphuric acid to form isopropyl sulphate which is then hydrolysed with steam to form sulphuric acid and IPA. Then, the crude IPA is distilled to the desired purity. The disadvantage of this process is being corrosive and high energy demanding for acid reconcentration and aqueous waste treatment.The direct hydration of chemical grade (90-99%) propylene is a more modern method which avoids the need for sulphuric acid. This process uses thermally stable polymeric catalyst. The third method uses acetone as the starting material unlike the first two methods. A very small amount of IPA is produced by the hydrogenation of acetone in the liquid phase. This process is only suitable where excess acetone is available. In USA indirect hydration is commonly used; whereas in Europe direct hydration process is more common. [11][12]
This project deals with direct liquid phase hydration of propylene and water in the presence of a strong acid solid catalyst for producing high quality isopropyl alcohol. Quality of the product, low capital expenditures and sensitivity for environment are taken in to consideration while selecting this type of process. Isopropyl alcohol manufacturing plant is designed with a capacity of 43,000 tons/year. ChemCAD program is used to simulate the flow of the process and calculate the inlet and outlet streams of the units.[11]
First “Process Selection and Description” part of the report tells about five different relevant patents about this manufacturing process and describes them one by one. By comparing each of them with respect to their properties, the patent which has better properties is selected. Then grading of the processes are made according to their properties and units. This part lastly describes the selected process in detail. Then, assumptions are implied at the beginning of the calculation part. Then comes the “Discussion” part which discusses the whole project. This part contains the discussion of choice of the process, assumptions, calculations, chemcad and discussion of the calculated design capacity. Lastly the report ends with the “Conclusion” part which implies a general view of the project with technical information and qualitative results.
2. MARKET INVESTIGATION AND CAPACITY DETERMINATION OF ISOPROPYL ALCOHOL PRODUCTION
2.1 Market Investigation
Shell, ExxonMobil, Sasol and Dow are the largest producers of IPA and they have over 72% of world capacity. It is oberved that oversupply resulted in decreased demand and two major plant closed because of lower margins in Western Europe in the last few years. Shell closed its Stanlow, United Kingdom IPA plant in 2003 which has a 90 thousand metric tons of annual capacity and also BP shut its 100 thousand metric ton-per-year Port Talbot, United Kingdom IPA plant in 2004.The following pie charts shows world consumption of IPA in 2005 and world consumption of IPA by end use,respectively. [13]
Figure 2.1World Consumption of IPA 2005 [13]
In direct solvent applications IPA is consumed over 50% of total demand. It is also used in surface coatings, inks, pesticide formulations, electronic applications, reagents and as a processing solvent in the production of resins.[13]
The largest use for IPA is as a solvent. The second largest use is as a chemical intermediate. IPA is also found in many everyday products such as paints, inks, general-purpose cleaners, disinfectants, room sprays and windshield deicing agents. It is also used as an ingredient in cleaners and polishers, as a chemical intermediate, and as a dehydrating agent and extractant. [15]
Isopropyl alcohol is cheaply available. As a preservative for biological specimens, it is cost-effective when compared to pure ethanol and comparatively non-toxic alternative to formaldehyde and other synthetic preservatives. [14]
Isopropanol is a major ingredient in "dry-gas" fuel additive. It helps water to solubilize in gasoline. With this way there exists no risk for freezing and accumulating of water in fuel tanks. Isopropanol is often sold in aerosol cans as a windscreen de-icer. [14]
.
Figure 2.2World Consumption of IPA by End Use 2005 [13]
Global IPA that is based on acetone production is expected to decrease with the increase of phenol capacity since acetone is a coproduct of phenol by the cumene peroxidation process. Worldwide IPA consumption is forecast to grow at an average annual rate of 2.0–2.5% . [13]
2.2 Capacity Determination
Data which the design capacity is based on is obtained from DIE, Turkish Institute of Statistics, United Nations Data and TR Prime Ministry State Planning Organization. Since isopropyl alcohol (IPA) with commercial code 290512 is not produced in Turkey, the consumption of this chemical is simply the difference between the imports and exports. [16] [17]
Table 2.1 Turkey Import-Export Data for IPA
291030 / Import-ExportYears / Amount
(kg)
1990 / 5339320
1991 / 4286986
1992 / 6297537
1994 / 8748677
1995 / 11388246
1996 / 11842072
1998 / 14002646
1999 / 14619008
2000 / 19236721
2002 / 18716240
2003 / 20613087
2004 / 22329510
2006 / 20056269
2007 / 21371744
2008 / 20506176
Table 2.1 is calculated from Table A.1.Because the data deviate within the years 1991 and 2008, it should be approximated using to 3-year moving and 5-year moving average in order to obtain a better fit.
Figure 2.3 Consumption of IPA in Turkey 1990-2008
The figure above shows the actual value of IPA consumption in Turkey for each year. As it can be observed above, the data points do not reveal a consistent pattern. So the 3 year moving and 5 year moving average of the data are needed.
Figure 2.43 year-moving consumption data of IPA in Turkey 1991-2007
The 3 year moving average data points are more consistent with each other. Although the first and the last data points are lost during taking the average, the remaining points are enough for modeling.
Figure 2.5 5 year-moving consumption data of IPA in Turkey 1992-2006
This data is smoothed using a five point moving average. Because the first two and last two points are lost during this calculation, the rest points are not satisfactory to fit a model although the points seem more consistent with each other.
Thus, the 3 year moving average data are more suitable in order to estimate production capacity.
Some models are fit to data obtained from 3 year moving average. The model equations are shown below:
- Polynomial Fit of 2th Degree:
y = -45563.35x2 + 183236172.51x - 184201861869.21 with R² = 0.980
- Exponential Fit:
y = y = 3E-67e0.0848x with R² = 0.889
- Logarithmic Fit:
y = 2147144497.59ln(x) - 16304265196.60 with R² = 0.950
- Linear Fit:
y = 1073884.07x - 2131804173.28 with R² = 0.950
Figure2.6 Models fit to 3 year moving average data
Figure2.7 Models fit to 3 year moving average data
The R2 values for polynomial, exponential, logarithmic and linear models are 0.980, 0.889, 0.950 and 0.950 respectively. Because the R2 values are very close to each other and each model is acceptable to present the IPA consumption of Turkey up to year 2008, the IPA consumption of the countries which have similar economic structures to Turkey should be taken into consideration. Turkey is a developing country. The IPA consumption curves in developed countries such as Austria, France, Germany, Greece, Italy, Spain, Switzerland and England which have similar economic structure to Turkey can give an idea how will the IPA consumption of Turkey be in the next 20 years. In order to estimate it, it should be calculated how many years are the economy of these countries ahead from Turkey. First of all, Gross National Products per capita of the countries mentioned above and Turkey, the annual growth rate ofTurkey for each year are found.(Table A.2)
The Consumption of the European countries can be found by;
Consumption = Production + Import - Export
Table A.4 and Table A.5 are used for this equation.
Table2.2 IPA Consumption for European Countries
AUSTRIA / FRANCE / GERMANY / GREECE / ITALY / SPAIN / SWITZERLAND / ENGLAND / TURKEY2006 / 7036199 / 42645500 / 56740100 / 2620394 / 32408479 / 47884765 / 13344496 / 42649229 / 20110554
2005 / 6944084 / 34535600 / 52438800 / 2189456 / 31493484 / 42534968 / 13646010 / 47768959 / 18020020
2004 / 4836630 / 41681100 / 50743100 / 2543966 / 28909337 / 50723523 / 14804728 / 21243805 / 22417994
2003 / 5298127 / 48228000 / 60924106 / 2768286 / 34873126 / 43843200 / 13696167 / 25800264 / 20768803
2002 / 6891829 / 55758300 / 54870746 / 1498192 / 29417469 / 29679605 / 15627125 / 28087778 / 18748785
2000 / 7968139 / 50552300 / 57170740 / 2053169 / 35660161 / 33383487 / 9945407 / 23296390 / 19283159
1999 / 5067889 / 54441168 / 57331840 / 2933902 / 36051122 / 43581902 / 23079964 / 25023459 / 14609990
1998 / 9473556 / 55296788 / 57274464 / 2866527 / 34659517 / 44698754 / 16549532 / 23718504 / 14057058
1997 / 10619050 / 56461492 / 57025984 / 2299666 / 34772377 / 43759067 / 15076150 / 24426324 / 15307153
1996 / 9352305 / 52489524 / 57976904 / 2467408 / 37232005 / 42722259 / 16278606 / 24715664 / 11850398
1995 / 9080604 / 43568078 / 28134884 / 2521342 / 37284212 / 38439476 / 15116416 / 26411416 / 11393426
1994 / 9731780 / 42624980 / 38609516 / 1713157 / 33939807 / 35216422 / 14973763 / 19826012 / 8756141
1993 / 47429376 / 1729665 / 30749339 / 14001270 / 625877 / 8315159
1992 / 50573712 / 1748639 / 20130414 / 15922216 / 6320805
From the annual growth of Turkey and GDP values of countries (Table A.3), it is calculated how many years are the economy of each specific country at specific years ahead from Turkey via the
equation:
[1]
N: years a country ahead from Turkey
α: annual growth of Turkey
GDP: Gross Domestic Product
From now on, Germanyis chosen as the sample country and all of the calculations will be shown according to the data of Germany.
For year 2006 for Germany,
GDP Turkey: 9073 $
GDP Germany: 31744 $ (Table A.3)
Growth rate of Turkey at 2006,α : 6.1% (Table A.2)
year difference between 2006 Germany and Turkey
The same calculation is done for each year and each country
Table 2.3 Year difference between developed countries and Turkey
Year difference between developed countries and TurkeyYear / Austria / France / Germany / Greece / Italy / Spain / Switzerland / UK
2006 / 23.068 / 22.014 / 21.151 / 17.169 / 20.561 / 19.363 / 24.153 / 22.792
2005 / 19.379 / 18.682 / 17.808 / 14.324 / 17.444 / 16.234 / 20.330 / 19.210
2004 / 16.785 / 16.257 / 15.477 / 12.302 / 15.381 / 14.075 / 17.562 / 16.634
2003 / 26.486 / 25.692 / 24.519 / 19.261 / 24.654 / 22.439 / 27.724 / 26.091
2002 / 20.049 / 19.568 / 18.748 / 14.252 / 18.916 / 17.005 / 21.228 / 19.619
2000 / 20.758 / 20.136 / 19.367 / 13.577 / 19.430 / 17.143 / 22.145 / 19.735
1998 / 46.136 / 44.656 / 43.294 / 29.088 / 43.308 / 37.029 / 50.164 / 44.138
1997 / 19.187 / 18.599 / 18.169 / 12.071 / 18.263 / 15.248 / 21.013 / 18.396
1996 / 21.059 / 20.411 / 19.994 / 13.276 / 20.062 / 16.586 / 23.019 / 20.042
1995 / 20.854 / 20.465 / 20.073 / 13.397 / 20.136 / 16.542 / 23.104 / 19.854
1993 / 17.983 / 17.719 / 17.319 / 11.473 / 17.246 / 14.041 / 20.568 / 16.748
1992 / 25.019 / 24.665 / 24.129 / 16.591 / 23.945 / 19.780 / 28.365 / 22.752
1991 / 164.215 / 163.303 / 159.658 / 112.667 / 159.290 / 132.320 / 190.016 / 152.317
From these values, the corresponding years of Turkey is calculated with respect to the developed countries.
Table 2.4 Corresponding years of Turkey to developed countries
Corresponding years of Turkey to developed countriesYear / Austria / France / Germany / Greece / Italy / Spain / Switzerland / UK
2006 / 2029 / 2028 / 2027 / 2023 / 2027 / 2025 / 2030 / 2029
2005 / 2024 / 2024 / 2023 / 2019 / 2022 / 2021 / 2025 / 2024
2004 / 2021 / 2020 / 2019 / 2016 / 2019 / 2018 / 2022 / 2021
2003 / 2029 / 2029 / 2028 / 2022 / 2028 / 2025 / 2031 / 2029
2002 / 2022 / 2022 / 2021 / 2016 / 2021 / 2019 / 2023 / 2022
2000 / 2021 / 2020 / 2019 / 2014 / 2019 / 2017 / 2022 / 2020
1998 / 2044 / 2043 / 2041 / 2027 / 2041 / 2035 / 2048 / 2042
1997 / 2016 / 2016 / 2015 / 2009 / 2015 / 2012 / 2018 / 2015
1996 / 2017 / 2016 / 2016 / 2009 / 2016 / 2013 / 2019 / 2016
1995 / 2016 / 2015 / 2015 / 2008 / 2015 / 2012 / 2018 / 2015
1993 / 2011 / 2011 / 2010 / 2004 / 2010 / 2007 / 2014 / 2010
1992 / 2017 / 2017 / 2016 / 2009 / 2016 / 2012 / 2020 / 2015
This result means that Turkish economy is supposed to reach to the level of 2006 German economy at 2027.
Now the population and IPA consumption per capita of each countries should be taken into consideration.
In order to calculate 2027 population of Turkey , 2005 year is taken as basis.
Population of Turkey at 2005 : 73922000
Population growth of Turkey at 2005: 1.3% [16]
In order to calculate 2027 GDP of Turkey , 2005 year is taken as basis.
GDP of Turkey at 2005 : 8408 $
GDP growth of Turkey at 2005: 7.4%
$
The consumption per capita for Germany;
$
The consumption per capita for Turkey at 2027;
$
In order to find the capacity of Turkey at 2027 consumption per capita is multiplied by predicted population of Turkey at 2027;
Kg/year
Power purchasing parity (ppp) has to be taken into consideration in order to reach reasonable data.
PPPTurkey, 2005 = 0.80 [16]
PPPGermany, 2005 = 0.91
The capacity of Turkey at 2027 considering power purchasing parity;
Kg/year
Table 2.5 Calculation of capacity with respect to Germany
GER / Pop_Tur_future / GDP_Tur_future / cons/capita_GR / cons/capita_TR / Capacity_exc_ppp / Capacity2006 / 98407805 / 40876.542 / 0.689 / 0.888 / 87371391.217 / 76886824.271
2005 / 93039928 / 29980.000 / 0.636 / 0.636 / 59182685.196 / 52080762.973
2004 / 89121274 / 23634.165 / 0.615 / 0.505 / 44970355.489 / 39573912.830
2003 / 98876465 / 41964.186 / 0.738 / 1.122 / 110927868.378 / 97616524.172
2002 / 90596610 / 25879.266 / 0.665 / 0.634 / 57466979.218 / 50570941.712
2000 / 88994913 / 23449.544 / 0.695 / 0.632 / 56240631.825 / 49491756.006
1998 / 118130904 / 112192.923 / 0.698 / 3.308 / 390799122.429 / 343903227.738
1997 / 84297965 / 17377.224 / 0.695 / 0.526 / 44369599.653 / 39045247.695
1996 / 85200334 / 18430.585 / 0.707 / 0.587 / 49981523.006 / 43983740.245
1995 / 84192973 / 17257.936 / 0.344 / 0.274 / 23076411.355 / 20307241.993
1993 / 79178711 / 12291.188 / 0.583 / 0.359 / 28392825.774 / 24985686.681
1992 / 85349269 / 18609.364 / 0.625 / 0.586 / 50034562.052 / 44030414.605
This calculation is done for each year and each country.(Table A.7, A.8, A.9, A.10, A.11, A.12, A.13).Then they are plotted together.
Figure 2.8 Consumption Projections of IPA Resins in Turkey Including European Countries
Figure 2.9 Consumption Projections of IPA Resins in Turkey Including European Countries
Final consumption data for Turkey are plotted in Figure 2.9. As can be seen in the figure, The logarithmic model fits best as a consumption projection of IPA in Turkey. From this model, the capacity for the IPA production process in 2025 was determined as 43,000 tons/year.
3. PROCESS SELECTION AND DESCRIPTION
3.1. Relevant methods and processes
Isopropyl alcohol (IPA) is produced by combining water and propylene. There are three processes in order to obtain it. Two of them use propylene as the starting material. These are; indirect hydration which is known as sulfuric acid process and direct hydration with a heterogeneous polymeric acid catalyst. In the third process acetone is used as the starting material. Low quality propylene is used during indirect hydration and it is commonly used in U.S.A.; whereas direct hydration requires high quality propylene and is commonly used in Europe. [12]
Indirect hydration is used in order to produce IPA by using sulfuric acid. Olefins are hydrated to alcohols by a two stage process. In the first step, olefins are esterified with sulfuric acid to alkyl sulfates. In the second step these alkyl sulfates are hydrolyzed. The whole reaction takes place at low temperature. Since this process is corrosive and demands high energy for acid reconcentration and aqueous waste treatment, it is not preferred in this project as the production process.
Direct hydration process uses thermally stable polymeric catalyst. Since its product quality improvement is high, its capital expenditures are low and it is less environmentally sensitive; it is chosen as the production process.[18]Simple reaction mechanism of direct hydration process is shown below and it is an exothermic reaction:
3.2. Comparison of the processes based on environmental, technical and economical aspects
3.2.1 Diisopropyl Ether Reversion in Isopropanol Production
Patent no: US 4,352,945
Date of patent: Oct. 5, 1982
Figure 3.1 Diisopropyl Ether Reversions in Isopropanol Production
The aim of this invention is to produce isopropyl alcohol and blending into gasoline by hydration of propylene.Figure 3.1 represents the flow diagram of this process. In this diagram some amount of produced DIPE is recycled; it is good to reuse some components, not to discharge them. And there are no environmental effects of the byproducts and units used.
In this patent, there is sufficient information about hydration reaction type, which is a down flow, trickle bed configuration using ion exchange catalyst in acid form, and dimensions used in production of water, IPA and DIPE. In the hydration stage, the percent propylene conversion is preferably maintained about 67% which is a high number but below 75% that is stated in the selected patent. The temperature for the hydration reactor is 143-179 0C , which is reasonable. Also high production of DIPE as a byproduct results in an extra unit called reversion and so a larger scale of plant is needed that increases the cost. After reversion unit, propylene, IPA and water are separated and propylene is recycled into the hydration unit.
For the separation part, the flow sheet and the description are not clear and well defined. It is stated that after hydration part a distillation tower, to separate IPA and water from DIPE, and a second one to separate water from IPA which is an azeotropic distillation. While in the selected patent, an azeotropic distillation is not needed. In addition there exists limited information about the distillation column in this patent, but in the selected one the reflux ratio, number of plates and dimensions of the column are given.
Additionally, it can be observed that the data as molar flow rates and compositions at the inlet and outlet streams of all the units are missing in this patent, while clearly well defined in the selected one.
All in all, since this patent is lack of a lot of necessary information and requires more units, it is not satisfactory to design an efficient plant using it.
3.2.2 Process for Production of Alcohols
Patent no: US 6,833,483
Date of patent: Dec. 21, 2004
Figure 3.2 A Schematic Diagram of a Catalytic Distillation Column Having two Catalyst Beds for the Catalytic Distillation Process
This process is related to production of alcohols via catalytic hydration of an olefin to the corresponding alcohol and dehydration of an azeotropic mixture including a first alcohol and water to produce the first alcohol in a substantially anhydrous state. There is more than one flow diagram in this patent, so one of them was chosen as a representative.
This invention was formed as an alternative to older conventional ones because of their complexity and loss of efficiency. Molar flow rates of all streams are available generally and there are a temperature range between 70C – 180C and a pressure range between 0.25MPa – 2.5MPa, which are not so high, but suitable for such a process. Purity of products is nearly 100%.