May 09, 2008

Value addition - Do Simple Things

In Distilleries where molasses or other sugar based raw material is fermented to Ethanol, the byproduct FUSEL OIL is a great nuisance & is often sold or used at fuel value, whereas it has a great potential of value addition due to its components majority of which is pentanol or Amyl alcohol.

Recently I successfully tested a process for value addition to it though its only first part but still opens up doors for further value addition / recovery of pure components.

In distillery processes where sugar based raw material is fermented, byproduct (FUSEL OIL) is generated at ~3 Kgs/Te of Ethanol. This means that India alone produced ~5.6 Million TPA of Fusel Oil in 2006-07 based on Ethanol production of 1850 MTPA.

The typical composition of Fusel Oil is as below - It contains

Moisture - 12%
C2 - 08%
C3 - 01%
C4 - 09%
C5 - 70%

Clearly majority of the organics is valuable C5 Alcohols.

The moisture content of 10-15% is a big problem in case of utilization of fusel oil either as fuel or if it is used for C5 recovery or if it is used for conversion into other derivatives. Therefore, first step is to remove moisture content in a cost effective manner.

The conventional methods of moisture removal are
  1. Ordinary Distillation

  2. Very poor yield of ~10%, Need lot of energy, Tall tower for separation, yet sensitive to disturbances.

  3. Extractive distillation

  4. Need third solvent, additional cost in terms of operation hardware etc. Not cost effective
Since the boiling points of each component do not differ greatly and they form more than 5 azeotropes, the distillation is really very complex & requires either multiple columns or very large column for separation. Actually, C5 in this mixture is further divided in two components n-C5 & i-C5 both are having a BP difference of only 2.8°C & relative volatility of 1.08.






Now come to the financial part, as I wrote that India produced ~5.6 Million Metric Tonnes of Fusel oil in 2006-07. This quantity at fuel value of Rs. 20 / Kg of fuel oil is Rs. 112 Million for manufacturers, whereas 70% of 5.6 i.e. 3.9 Million TPA of Amyl alcohol at an average price of Rs. 100 / Kg can generate 390 million Rs. which is 3.5 times of fuel value. So it is worth considering value addition project for Fusel Oil.

In view of above, I used a different process i.e. salting out the moisture - this is a common practice but is not followed at large scale. This reduces the moisture from 12 to 5%. In this process wet fusel oil is taken in the agitated tank. Now Sodium carbonate is charged ~20% of the total weight i.e. if you take 1000 Kg of fusel oil charge ~200 Kg of salt. Agitate it thoroughly at high speed for ~45 Minutes & then let it settle - decant the layers for separation. Now you have a fusel oil with 5% moisture.

In the next step I used another conventional process (Contact Me for more details) to bring down the moisture to <1%. The benefit of this process is that it reduces the cost of moisture separation using well known methods.

The learning from this exercise is that you dont need too complex processes for either cost reduction, value addition or for energy conservation. First understand the properties of the material & analyse its data and then go for simple processes which can increase the productivity of your plant.

In this case, the further value addition would come from either the recovery of valuable components e.g. C5 or from the conversion of these alcohols to some other useful derivatives e.g. Amyl nitarte which is also called Banana oil & is used as a fragrance material for Banana like odor.

Here the most common method stated in the literature is to convert this mixture into esters using acids e.g. Amyl acetate or butyrate. But if I go for this again the separation of C2, C3 esters is difficult as they also have very close boiling points. So my strategy here is different. I will first react them in such a way that C2, C3 will separate on its own due to volatile nature thus leaving behind majority of C5.

After this step, I can recover C5 easily & will convert it back to final product.
Cost is of course the criteria in selecting various components.

Dont you think this is a better way then going for large distillation column & wasting lot of energy at a reflux ratio of 20 - 30???

Think on it......Do some initial Financial calculation for estimating the benefits against your time to justify the efforts in planned direction.............then SHOOT IT.

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1 comments:

chemsquare said...

Hi
I was very much helped by the information with this article.
Many thanks at you very fascinating resource.

Bye

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