Conversion Of Vegetable Oils To Bio Diesel

Abstract

The instant invention relates to the conversion of vegetable oils/ animal fats to biodiesel and in particular to a processing plant for conversion of vegetable oils to biodiesel.

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Field Of Invention
The instant invention relates to the conversion of vegetable oils/ animal fats to biodiesel and in particular to a processing plant for conversion of vegetable oils to biodiesel.
Background of the Invention
Increasing energy demand, environmental concerns and depletion of fossil fuel reserves have led to the search for alternate fuels. Vegetable oil presents one such alternative, which is looked as a potential economic alternate. Vegetable oils cannot be used directly in plants as they lead to various engine problems including injector coking, ring sticking, thickening of the engine lubricating oil etc. The reasons for such problems in the plant include high viscosity and non-volatility of vegetable oils.
High viscosity of vegetable oils (30-200 cSt @ 40°C) as compared to diesel oil (4cSt @ 40°C) leads to unsuitable pumping and spray characteristics. Larger size fuel droplets are injected from the fuel injector nozzle instead of a spray of fine/ micron size droplets, leading to inadequate air-fuel mixing. Poor atomization and inefficient mixing of fuel with intake air contributes to incomplete combustion of the fuel. This in turn results in an increase in particulate formation, combustion chamber deposits, injector coking, piston deposits, ring sticking, dilution of lubricating oil with unburnt fuel etc.
Due to the various problems caused by direct usage of vegetable oil in the engines, several techniques have been explored/ researched to bring down the physical and thermal properties of vegetable oils closer to mineral diesel oil. These techniques include direct use of straight vegetable oils, blending of vegetable oils with diesel, micro emulsification, thermal-cracking (pyrolysis), hydrogenation and transesterification etc.

The biodiesel is considered to be a good alternate of the other alternative/ conventional fuels used in diesel engines, which are costly, and also lead to number of other problems.
The various advantages achieved by using biodiesel include the following: (i) It is biodegradable and non-toxic, assuring safe handling and transportation, (ii) it does not contain sulfur or aromatic compounds thus it contributes to the reduction of exhaust emissions, (iii) it is produced from renewable sources (such as vegetable oils, waste cooking oils etc.), (iv) it can be produced domestically, thus reducing a country's dependence on foreign fuel, (v) it does not contribute to a net rise in the level of carbon dioxide in the atmosphere, and consequently to the greenhouse effect and (vi) minor modifications of diesel engines can allow them to perform very efficiently when fuelled with biodiesel blends or even pure biodiesel.
In recent years, transesterification process has been found to be the most feasible for biodiesel production wherein vegetable oils are reacted with primary alcohols in presence of catalysts (Acidic/basic/ enzymatic), and the bonds to the triglycerides present in vegetable oils are broken, thus the bulkier molecule of triglyceride is broken in to several smaller hydrocarbon molecules. This reaction is commonly referred as transesterification, and the main reaction product is biodiesel.
A number of biodiesel plants have been designed and used for production of biodiesel from vegetable oil. The conventional biodiesel plants have a number disadvantages including very high cost, very large size, highly complicated design, complicated production process, large manpower required, large amount of raw material requirement etc.

Description of the Invention:
In order to obviate the above drawbacks, the instant invention discloses a biodiesel plant or plant, which results in conversion of vegetable oil to biodiesel.
Still the instant biodiesel plant or plant is very economic and smaller in terms of size.
Also, the instant invention provides an advantage by reducing the manpower required for producing the biodiesel from the vegetable oil by means of the instant plant.
Still another advantage is that any type of catalyst can be used in the biodiesel plant including basic, acidic or enzymatic.
Still another advantage is that the instant biodiesel plant requires less amount of energy, and does not require expensive heat exchanger.
The instant biodiesel plant is suitable for rural applications and thus can be installed in villages. The capacity of the instant biodiesel plant cater to the local needs and serves the best in the locally available resources, hence the fuel transportation related costs are saved. The instant biodiesel plant is very energy efficient and user-friendly. Thus, the operating cost of this plant is significantly low, additionally the costs associated with fuel transportation and manpower is also lower. Also, locally available materials can be used so no collection costs is involved and the machinery cost is also low.
The present invention is not intended to be restricted to any particular form or arrangement, or any specific embodiment, or any specific use, disclosed herein, since the same may be modified in various particulars or relations without departing from the spirit or scope of the claimed invention hereinabove shown and described of which the apparatus or method shown is intended only for

illustration and disclosure of an operative embodiment and not to show all of the various forms or modifications in which this invention might be embodied or operated.
Figure 1 illustrates an embodiment of the biodiesel plant or plant. Herein the various important parts or components of the biodiesel plant are described as follows:
Preheating unit or mixer (1): It is an insulated cylindrical vessel (conical at its lower end) made of mild steel, which is open from top. A steam jacket (3) is provided to heat the contents of the mixer up to 50°C or higher. The steam jacket heats the vegetable oil so that it can be transferred to the reactor. Agitation or stirring of oil or alcohol and catalyst is done by means of a geared motor stirrer (M1). Herein the vegetable oil or catalyst and alcohol are poured in the preheating unit (1). The steam jacket receives the steam to heat the oil or alcohol and catalyst when the steam valve S3 is open. The steam is received from the steam header (15) through a connecting means when steam valve S3 is open. The preheating unit is connected to the reactor by connecting means and transmits the heated oil to the reactor by means of mixer operating valves MO1, MO2 and reactor operating valve RO1.
Reactor (2): It is a closed insulated vessel made of mild steel .It can be heated by passing steam through the steam jacket (5) around it. The steam is generated using a diesel fired non-IBR boiler or steam header (15). The steam valve S1 is opened so as to transfer the steam to the reactor steam jacket (2). A motor M3 driven stirrer is provided in the reactor. The reactor is conical in shape for easy recovery of the reacted products. The reactor is equipped with temperature sensors and PID controller. The temperature controller (6) is equipped to control the temperature of the reactor. The reactor is the most important part of the biodiesel plant as transesterification reaction is performed in the reactor (2). Reactor works under vacuum. The heated vegetable oil is transferred to the

reactor from the preheating unit and thereafter the mixture of catalyst and alcohol heated and stirred in the preheating unit is transferred to the reactor. The vegetable oil and mixture of catalyst and alcohol is heated and stirred in the reactor so that the reaction can start in the reactor. The reaction is allowed to take place for 45-50 minutes in the reactor and the condensed alcohol is transferred to the methanol receiver (17). When the reaction has taken place in 45 to 50 minutes and the condensed alcohol has been transferred to the methanol receiver transmitted than and the condensed alcohol has been transferred to the methanol receiver the reaction mixture in the reactor is transferred to the separator or washer.
Separator (7): The separator is similar to that of the mixer (1) and is used for washing and separation of esters (Biodiesel) from glycerol. The separator also comprise of a motor driven stirrer (M2). Similar to the reactor and mixer the separator also comprise of a steam jacket (8). Separator also works under vacuum. The valve reactor operating valve RO2 and Separator operating Valve SO1 are opened with pump M6 bein turned on for separating the biodiesel. The separator (7) receives the reaction mixture from the reactor when the pump MO2 is turned on and the valve S2 is opened. For separation of biodiesel from the reaction mixture warm water is mixed to the reaction mixture or product followed by switching on the motor M2 and opening the valve S2 to maintain heat. After 15-20 minutes the steam valve S2 is closed and motor M2 is stopped. The mixture is than allowed to settle down for 6-8 hours and than the separator operating valves SO2 and SOS are opened. The fluid is checked for change in color and viscosity. When the color of the fluid coming out becomes pale than the separator operating valves SO2 and SOS are closed. The washing process is repeated for 2-3 times by mixing the warm water, stirring and than settling the mixture and getting out the thick layer of glycerol.
Condenser Unit (10): Condenser unit (10) or methanol recovery unit is a water condensation column for recovery of methanol. This condensation is done under

vacuum conditions hence a vacuum pump (13) is attached to it. Cold water is supplied through a motor from water tank through water inlet (18) for this purpose. A sight window, made of glass (11) is provided below the methanol recovery unit so as to keep track of the volume of methanol condensed. The glass aperture or the glass window is checked for the quantity of condensed alcohol from time to time. If the rate of condensation is very high and the glass window (11) is getting filled than the methanol recovery unit valve MRS is opened and excess methanol is stored in methanol receiver (14). The condensed methanol is transferred to the reactor (2) for recycling by opening the tank valve TV1, reactor opening valve R05 turning on the motor M4.
Foots Tank (19): Foots tank (19) is an open rectangular tank having two compartments to collect glycerol and water that is used for washing respectively. The separator operating valves SO2 and SOS are opened when the separator
The process involved in the formation of biodiesel by means of the biodiesel plant is illustrated below. The boiler is first checked for the steam and vegetable oil is sent to the mixer (1). The main valves in the steam outlet of the mixer, reactor and the separator are opened fully and bypass valves are opened partially. The steam valve S3 is opened so as to transfer the steam from the boiler to the steam jacket of the mixer. The steam is transferred to the steam jacket of the mixer until the temperature of the vegetable oil reaches 50° C. The motor M1 is turned on to stir the vegetable oil in the mixer. When the temperature of the vegetable oil in mixer has reached 50° C, the vegetable oil is transferred to the reactor by opening the mixer operating valves MO1 and MO2, reactor operating valve RO1 and Pump M6. When whole of the heated vegetable oil transfer to the reactor is complete, the preheating unit is filled with a mixture of alcohol and catalyst. When the temperature of the mixture of alcohol and catalyst reaches 50° C than the mixture is also transferred to the reactor. The steam valve S3, reactor operating valve RO1, mixer operating valves MO1 and MO2 are closed and motor M1 is switched off. The steam valves S1, S5 and S6 and

motor M3 are started and the temperature of the reactor containing the vegetable oil and the mixture of catalyst and alcohol is checked continuously through the temperature clock and control panel. The temperature is automatically controlled by controlling steam through actuator-operated valve (S4) and the geared motor gives the required stirring for the reaction. The methanol recovery unit valve MR1 is kept open. The glass aperture or glass window is used to check for the condensed methanol. If the alcohol is received at higher rates than the methanol is collected in the methanol receiver tank (17) from where it can be transferred back to the reactor by opening the motor M4 and opening tank valve TV1. The condensed alcohol is put back in the reactor from the glass aperture by opening the methanol recovery unit valve MR2. The reaction mixture is transferred to the separator/washer. After 45-50 minutes when the reaction in the reactor is complete the steam supply to the reactor is stopped by closing valves S1, S5 and S6 and MR2. The motor M2 is also shut down. The reaction mixture from the reactor is then transferred to the separator/ washer unit. Reactor operating valve RO2, Separator operating valve SO1 and Motor Pump M6 is turned on to transfer the reaction mixture to the separator/ washer from the reactor. In separator, warm water is mixed (10% V/V) with the reaction mixture or product received from the reactor and than motor M2 is switched on and steam valve S2 is opened to maintain the temperature constant. After 15-20 minutes, the steam valve S2 is closed and motor M2 is stopped. The reaction mixture is stirred in the separator and then allowed to settle down for 6-8 hours after the steam valve S2 is closed and motor M2 is put off. After the mixture is allowed to settle for 6 - 8 hours, the separating operating valves SO2 and SOS are opened and fluid coming out of the pipe above foots tank is observed for change of color and viscosity. When the thick layer of glycerol has come out and less viscous and pale liquid starts coming out, valve SO2 is closed. This process of mixing warm water, stirring the reaction mixture and than settling the stirred warm water reaction mixture is called the washing process and it separates the glycerol from the biodiesel produced. When the washing process has been repeated for two to three times in the separator, the biodiesel left in the separator is transferred to the biodiesel

receiver by opening the separator opening valve SOS. Further biodiesel is transferred to biodiesel storage tank by opening tank valve TVS and using Pump M7.
It will readily be appreciated by those skilled in the art that the present invention is not limited to the specific embodiments shown herein. Thus variations may be made within the scope and spirit of the accompanying claims without sacrificing the principal advantages of the invention.

We claim:
1.) A plant for conversion of vegetable oil to biodiesel comprising:
- a preheating unit for heating the vegetable oil or a mixture of
alcohol and catalyst;
- a reactor for the completion of the transesterification reaction of
vegetable oil and the mixture of catalyst and alcohol; the vegetable
oil and the mixture of catalyst and alcohol is received from the
preheating unit;
- a separator for gravity separation/ washing of the reaction mixture
received from the reactor by stirring, heating and gravity settling the
reaction mixture so as to separate the glycerol from the biodiesel
produced;
- a unit for recovery of glycerol from the reaction mixture in the
reactor; and
- a unit for receiving the biodiesel extracted from the separator;
2.) A plant as claimed in claim 1 wherein the preheating unit preheats the vegetable oil and a mixture of catalyst & alcohol using process steam by opening the steam valve S3 and also stirring the mixture of catalyst and alcohol or vegetable oil by means of a motor M1
3.) A plant as claimed in claim 1 wherein any kind of catalyst can be used including acidic, basic or enzymatic.
4.) A plant as claimed in claims 1 or 2 wherein the heated vegetable oil is transferred to the reactor and the heated mixture of alcohol and catalyst is also transferred to the reactor so as to start the reaction after stirring and heating the mixture of heated vegetable oil, catalyst and alcohol.

5.) A plant as claimed in claims 1 or 4 wherein the reaction of the vegetable oil, catalyst and alcohol received from the preheating unit is done in the reactor for 45-50 minutes and the methanol recovered during the reaction is transferred to the methanol recovery unit.
6.) A plant as claimed in claim 1 wherein the reactor receives the steam from the boiler or steam header by opening the steam valves S1, S5 and S6 and the reaction mixture is stirred by the stirrer M3..
7.) A plant as claimed in claims 5 or 6 wherein the methanol recovered from the reactor goes to the glass aperture through the methanol recovery unit valve MR1 and is than transferred to the methanol recovery unit.
8.) A plant as claimed in claim 1 wherein the reactor comprises of a temperature controlling device and a temperature sensor so as to control and maintain the required temperature of the mixture of catalyst, methanol and vegetable oil.
9.) A plant as claimed in claim 1 or 5 wherein the reaction of the catalyst, alcohol and vegetable oil is conducted under partial vacuum.
10.) A plant as claimed in claim 1 wherein the separator receives the reaction mixture from the reactor from which the excess methanol has been recovered.
11.) A plant as claimed in claim 10 wherein the washing process is done by mixing warm water in the reaction mixture and stirring the same in the separator for 15-20 minutes and than the stirring motor of separator and separator steam valve is closed.

12.) A plant as claimed in claim 1 or 11 wherein the heated stirred reaction mixture with warm water is allowed to settle under gravity for 6-8 hours followed by transfer of the glycerol to the glycerol recovery unit.
13.) A plant as claimed in claim 1 or 12 wherein the washing process is repeated for two to three times and thus glycerol is extracted two to three times in order to improve the purity and quality of biodiesel thus produced.
14.) A plant as claimed in claim 1 or 13 wherein after completion of washing process in the separator for two to three times, final product biodiesel is transferred to the biodiesel storage unit.