Industry Consultancy

Title: Synthesis of liquid biofuels waste

Consultancy received from: Rajaram Solvex Ltd. Islampur

Brief overview of the project:

In the current project, a oil refinery waste ie. Acid oil from Rajaram Solvex was used for the synthesis of biodiesel. Acid oil which is a by-product of vegetable oil refinery operations may prove a viable source, as it is cheap and readily available in significant quantities as unutilized by-product. Chemical composition and fuel properties of acid oil are determined. Acid oil predominantly consists of long chain free fatty acid mixture along with small amounts of mineral acids (1- 2%), free moisture (5-8%), phospholipids and sterols (8-10%) which all impart a characteristic pungent odour and dark brown colour to the acid oil. Acid oil because of its oxygenated nature and chain type of configurational compounds present has fuel properties which are different than diesel fuel. Heating values are slightly lower while viscosity and ignition values are higher than diesel fuel. If viscosity of acid oil is reduced and brought closer to diesel fuel, it can also be used as alternative to diesel fuel. Viscosity of acid oil is reduced by modified esterification process using acid type of catalysts.

The objective of the present study is

(i) To produce biodiesel from acid oil.

(ii) To compare the fuel properties of biodiesel thus produced with standard specifications of biodiesel.

(iii) Blending of biodiesel sample with diesel fuel 

Experimental Procedure

Acid oil sample used in the present study was obtained from Rajaram Solvex Ltd., Islampur, a nearby high scale vegetable oil refining complex. Study was carried out in a closed type of reactor provided with adjustable electrical heating unit, a continuous methanol recirculation and methanol vapors escaping arrangements. Reaction mixture was maintained at 70 o C, methanol-water vapors were condensed, and recycled back throughout the course of reaction. Excess methanol used was recovered and reused in subsequent batches. Resulting crude ester mixture was washed thrice with equal amounts of water, allowed to stand overnight. Water settled at bottom was separated. Top ester layer produced was separated and batch distilled. Escaping vapors were condensed and collected as neat biodiesel. Reactor used had a capacity to process ten liters of acid oil per batch. About 75 to 80% of acid oil added was obtained as neat biodiesel.

Based upon foregoing experimental results the following conclusions are drawn

(i) Acid oil which is a byproduct of vegetable oil refineries can be used for biodiesel developmental activities. Since acid oil contains free fatty acids and moisture levels much higher than refined vegetable oils conventional transesterification process does not produce any desired results.

(ii) Biodiesel of acceptable quality can easily be produced by Esterification process.

(iii) Blending of biodiesel with diesel fuel produces a blend whose fuel properties vary with the composition and properties of neat fuels used. Carbon chain length (Z), number (n), location (?) of double bonds and relative amounts (m) of compounds present all influence the fuel properties of the blends. Fuel properties of biodiesel fuel produced vary with the source of feed stock used.