Description:4. DESCRIPTION
Technical Field of the Invention

The invention relates to the field of chemical engineering and renewable energy. More specifically, it relates in focusing on an improved process for biodiesel production utilizing hydrodynamic cavitation (HC) phenomenon to perform the “Transesterification” reaction for converting any fat/oil sources into biodiesel with enhanced energy efficiency and reduced reaction time.

Background of the Invention

The increasing environmental concern about greenhouse gas emission, environmental pollutions, soaring price of petroleum-based fuel sources and the depleting resources of fossil fuels have prompted the researchers to develop or identify alternative and renewable fuel sources. In the present scenario, biofuels, the ones those are derived from various biological sources, have gained immense attention as a potential substitute to fossil fuels due to several advantages such as renewability, better gas emission and biodegradability. One of the key benefits of biofuels is their potential to reduce greenhouse gas emissions compared to fossil fuels.

This is particularly important in the context of climate change, as the agricultural sector is also a significant contributor to greenhouse gas emissions and vulnerable to the impacts of a changing climate through burning of crop residue. Biodiesel has been recommended as one such biofuel, a potential substitute of diesel with a superior quality, as it is essentially Sulphur free and non-aromatic compared to conventional diesel that contains up to 500 ppm SO2 and 20–40 wt% aromatic compounds. Replacing fossil fuels with biodiesel will lower the need for fossil fuel imports and reduces its price and generate economic sustainability of the nation.
The standard reaction for converting oils/fats into biodiesel is through transesterification where oil reacts with alcohol/acid in presence of a catalyst to get converted into esters (biodiesel) and glycerine as the by-product. However, inefficient mass transfer is a major limitation in such biphasic heterogeneous reactions. Although many types of vigorous mixing have been investigated to address this requirement, most of them are energy intensive. Hence, optimal mass/heat transfer is doubtless the key for enhancing biodiesel production. While cavitation has recently been recognized as a potential route for the same due to the unique physical and chemical inherent conditions generated, the conventional ultrasonic or static hydrodynamic cavitation (HC) devices have scalability issues, high energy consumption, low processing capacity. The present innovation intends to describe a unique dynamic HC reactor having customised configuration that can produce intensified cavitation effect generated by a specially configured high-speed rotor inside a stationary chamber to accelerate the mass transfer and reaction kinetics of the transesterification process by enhancing the interphase mass transfer area cutting down the standard processing time significantly. Integrating the HC reactor, the present invention also describes a complete biodiesel production process based on cavitation phenomenon.

The conventional biodiesel production process suffers from several disadvantages:
a. A standard transesterification reaction time of 120-180 min is required to convert the oil/fats into biodiesel.
b. A reaction temperature of 55-60? C is required. Hence, pre-heating of the feed materials is needed making the process energy intensive.
c. In-effective interphase mass transfer lowering the yield of the process.
d. Interrupted production of biodiesel due to uncertain availability of a fixed raw material.
e. Long processing time lowering the plant capacity.
“Hydrodynamic cavitation” is a physical phenomenon that leads to the generation or formation of multiple cavities or vapor bubbles inside the flowing liquid due to a sudden drop in local pressure created by certain geometric configuration inside the reactor followed by violent collapse of the bubbles upon pressure recovery in the flow path creating shock waves. This ultimately results in accumulation of tremendous localised forces which impart several physical and chemical alterations in the liquid medium such as shock waves, micro-turbulence, shear forces and sometimes leading to formation of highly reactive oxidative free radicals through molecule breakage under localised high magnitude pressure pulse (100 to 5000 atm) and extremely high temperature (1000 to 10000 K).

The major advantages that can be achieved through harnessing the cavitation energy in biodiesel production process are:
1. Significant reduction in the transesterification reaction time to 5-10 min compared to the conventional route.
2. Ambient reaction temperature. Hence, no pre-heating of the feed material is required.
3. Highly effective interphase mass transfer enabling high yield of the process.
4. Steady production of biodiesel as raw materials in blended forms are also suitable to feed with this process.
5. Less processing time enhancing the plant capacity.

While few works have been reported on cavitation-based biodiesel production process, most of them are restricted in small lab scale studies using ultrasound-based cavitation effective in a very small region in the medium or with conventional static hydrodynamic cavitation devices like venturi or orifice meters those have scalability issue, chocking problem, ineffective cavitation phenomenon, and incomplete reaction.

Brief Summary of the Invention

The following presents a simplified summary of the disclosure in order to provide a basic understanding to the reader. This summary is not an extensive overview of the disclosure, and it does not identify key/critical elements of the invention or delineate the scope of the invention. Its sole purpose is to present some concepts disclosed herein in a simplified form as a prelude to the more detailed description that is presented later.

It is a primary object of the invention is to develop a process for fast, accelerated and effective biodiesel formation from any edible/non-edible oil source.

It is yet another object of the invention to apply hydrodynamic cavitation phenomenon for accelerating the transesterification reaction for biodiesel formation.

It is yet another object of the invention to develop a unique cavitation reactor for enhanced cavity formation with intensified cavitation effects.

It is yet another object of the invention to optimize the reactor in such a way so as to harness the maximum cavitation energy as possible to perform the chemical reactions for biodiesel production.

It is yet another object of the present invention to use cavitation for performing the transesterification reaction at ambient temperature omitting the requirement of feed material pre-heating making the overall process energy saving.

It is yet another object of the present invention to bring down the standard reaction time of 120-180 min conventionally to 5-10 min with a significant saving in the energy consumption.

It is yet another object of the present invention to integrate the reactor/prototype in-line to any existing biodiesel process operation to enhance the production capacity.

According to an aspect of the present invention, a hydrodynamic cavitation-based biodiesel production system is disclosed. The system comprises an oil pre-heating unit, mixer-1, a pre-treatment unit, the hydrodynamic cavitation-based transesterification unit, post pre-treatment unit, a mixer-2, a methanol separator/methanol recovery unit, a washing tank, a separating unit, a storage tank.

In accordance with the aspect of the present invention, wherein the pre-treatment units for degumming (the initial purification step of feed material to remove moisture and other impurities), esterification (to reduce the free fatty acid (FFA) content of the oil), and transesterification caused by hydrodynamic cavitation process, and finally the purification of biodiesel and the by-product that is formed, glycerin.

In accordance with the aspect of the present invention, wherein the multiple cavitation reactor can be arranged parallelly in-line with the process based on the scale of production. Any unprocessed oil or fat (vegetable, used cooking, or animal fat) with an FFA content of less than 2% may be used as a feed ingredient, either alone or in a mixture. The characteristics of the produced biodiesel will change depending on the composition of the feed.

In accordance with the aspect of the present invention, wherein the stator-rotor configuration of the reactor allows for the production of cavitation effects in the liquid medium via numerous indentations made on the surface, where localized pressure drop occurs.

In accordance with the aspect of the present invention, there is no bulk increase in the temperature of the processing liquids.

In accordance with the aspect of the present invention, highly effective homogenization of the different phases occurs that enables effective interphase mass transfer during the reaction.

In accordance with the aspect of the present invention, with ambient temperature sufficient for the reaction to happen, no pre-heating of the feed material before transesterification is required saving a significant amount of energy.

Further objects, features, and advantages of the invention will be readily apparent from the following description of the preferred embodiments thereof, taken in conjunction with the accompanying drawings.

Brief Description of the Drawings

The invention will be further understood from the following detailed description of a preferred embodiment taken in conjunction with an appended drawing, in which:

Fig. 1 illustrates the entire process of the cavitation-based biodiesel production process, according to an exemplary embodiment of the present invention.

Fig. 2 illustrates the separately assembly of cavitation reactor, according to the exemplary embodiment of the present invention.

Fig. 3 illustrates the inside view of the reactor, according to the exemplary embodiment of the present invention.

Fig. 4 illustrates the step wise process to form biodiesel from crude palm styrene, according to the exemplary embodiment of the present invention.
Detailed Description of the Invention

It is to be understood that the present disclosure is not limited in its application to the details of construction and the arrangement of components set forth in the following description or illustrated in the drawings. The present disclosure is capable of other embodiments and of being practiced or of being carried out in various ways. In addition, it is to be understood that the phraseology and terminology used herein is for the purpose of description and should not be regarded as limiting.

The use of “including”, “comprising” or “having” and variations thereof herein is meant to encompass the items listed thereafter and equivalents thereof as well as additional items. The terms “a” and “an” herein do not denote a limitation of quantity, but rather denote the presence of at least one of the referenced items. Further, the use of terms “first”, “second”, and “third”, and the like, herein do not denote any order, quantity, or importance, but rather are used to distinguish one element from another.

According to an exemplary embodiment of the present invention, a hydrodynamic cavitation-based biodiesel production system is disclosed. The system comprises an oil pre-heating unit, mixer-1, a pre-treatment unit, a hydrodynamic cavitation reactor, post-treatment unit, a mixer-2, a methanol separator/methanol recovery unit, a washing tank, a separating unit, a storage tank.

In accordance with the exemplary embodiment of the present invention, wherein the oil pre-heating unit includes temperature control mechanisms to precisely regulate the pre-treatment oil temperature, optimizing the subsequent processes.

In accordance with the exemplary embodiment of the present invention, wherein the mixer-1 is responsible for mixing the pre-heated oil with acid-methanol during the pre-treatment phase (esterification process) and prepares the oil for further processing and facilitates the subsequent transesterification processes to convert oils into biodiesel and glycerin.

In accordance with the exemplary embodiment of the present invention, wherein the pre-treatment unit plays a critical role in the purification of the oil. It performs two primary functions which are degumming to remove the phospholipids and other impurities in the oil, enhancing its quality. Simultaneously, esterification occurs, reducing the free fatty acid (FFA) content of the oil for transesterification, a crucial biodiesel conversion process.

In accordance with the exemplary embodiment of the present invention, wherein the methanol separator/methanol recovery unit is responsible for separating and recovering excess methanol from the esterification reaction. High-efficiency separation methods, potentially involving a distillation column with temperature and pressure control, ensure the recovery of pure methanol for reuse in subsequent stages, making the process more sustainable.

In accordance with the exemplary embodiment of the present invention, wherein the hydrodynamic cavitation reactor in the transesterification unit is equipped with adjustable parameters to accommodate various feedstock compositions and processing requirements, including variable rotor speeds and cavity geometries.

In accordance with the exemplary embodiment of the present invention, wherein the mixer-2 is responsible for the preparation of the sodium hydroxide (NaOH) and methanol mixture is then directed into the transesterification unit to initiate the reaction.

In accordance with the exemplary embodiment of the present invention, after transesterification, the raw transesterified oil is separated into two layers of separating unit are the bottom layer contains crude glycerin, a by-product of the reaction and the upper layer comprises crude biodiesel, the desired product of the process.
In accordance with the exemplary embodiment of the present invention, wherein the washing tank is used to purify the crude biodiesel and warm water is employed for the washing process, removing any residual impurities and unwanted substances from the biodiesel.

In accordance with the exemplary embodiment of the present invention, wherein the second separation unit is responsible for removing moisture from the washed biodiesel through a heating process, ensuring the final product meets quality standards.

In accordance with the exemplary embodiment of the present invention, wherein the storage tank is designed with an inert gas blanket and temperature control systems to maintain the stability and quality of the separated and purified biodiesel during long-term storage.

In accordance with the exemplary embodiment of the present invention, wherein the reduced reaction time of 5-10 minutes in step e is achieved through precise control of cavitation intensity within the hydrodynamic cavitation reactor.

In accordance with the exemplary embodiment of the present invention, wherein the reduction in required reaction temperature from a range of 55-60°C to ambient in step ‘e’ is achieved through precise temperature control mechanisms within the hydrodynamic cavitation reactor.

In accordance with the exemplary embodiment of the present invention, wherein the >99% yield in biodiesel production in step ‘e’ is attained by optimizing the cavitation reactor's operating parameters, including pressure and flow rates.

Referring to the figures, Fig. 1 illustrates the entire biodiesel production process using hydrodynamic cavitation (6) based route involves several steps to convert feedstock oils (such as vegetable oil or animal fat) into biodiesel. Here is the entire biodiesel production process using hydrodynamic cavitation:

Oil Pre-Heating (1): The feedstock oil is first pre-heated using an oil pre-heating unit with temperature control mechanisms. This unit ensures that the oil is at the optimal temperature for subsequent processing steps.

Mixer-1 (2): the pre-heated oil is mixed with acid-methanol and mixer-1 is responsible for this mixing, which prepares the oil for further processing and facilitates degumming and esterification processes.

Pre-Treatment Unit (4):
Degumming: The pre-treatment unit plays a critical role in the purification of the oil. It removes phospholipids and other impurities in the oil, enhancing its quality.

Esterification: Simultaneously with degumming, esterification occurs in this unit. Esterification reduces the free fatty acid (FFA) content of the oil, which is crucial for the transesterification process and biodiesel yield.

Methanol Separator/Methanol Recovery Unit (5): This unit is responsible for separating and recovering excess methanol from the esterification reaction. High-efficiency separation methods, such as distillation with temperature and pressure control, are employed to recover pure methanol for reuse in subsequent stages, making the process more sustainable.

Hydrodynamic Cavitation Reactor (6): The transesterification unit includes a hydrodynamic cavitation reactor equipped with adjustable parameters, including rotor speed and cavity geometries. This reactor is where the actual transesterification process takes place. The adjustable parameters allow the system to accommodate various feedstock compositions and processing requirements.

Mixer-2 (3): Before entering the hydrodynamic cavitation reactor, Mixer-2 is responsible for preparing the sodium hydroxide (NaOH) and methanol mixture, which is then directed into the reactor to initiate the transesterification reaction. Within the hydrodynamic cavitation reactor, the combination of mechanical shear forces and cavitation-induced conditions promotes the transesterification of triglycerides in the oil with methanol, resulting in the formation of biodiesel and glycerol.

Separating Unit (7): After the transesterification reaction, the raw transesterified oil is separated into two layers. The bottom layer contains crude glycerin (a by-product of the reaction), while the upper layer comprises crude biodiesel, the desired product of the process.

Washing Tank (8): The crude biodiesel is further purified in a washing tank. Warm water is employed for the washing process, which helps remove any residual impurities and unwanted substances from the biodiesel.

Second Separation Unit (9): This unit is responsible for removing moisture from the washed biodiesel through a heating process, ensuring the final product meets quality standards.

Storage Tank (10): The purified biodiesel is stored in a specialized tank designed with an inert gas blanket and temperature control systems. These measures help maintain the stability and quality of the separated and purified biodiesel during long-term storage.

This entire biodiesel production process using hydrodynamic cavitation is designed to be efficient, yield high-quality biodiesel, and promote sustainability through methanol recovery and optimized cavitation reactor parameters. The process allows the conversion of feedstock oils into biodiesel suitable for various applications, including as a renewable and environmentally friendly fuel source.

Fig. 2 illustrates separately assembly of cavitation reactor and method for biodiesel production. Before delving into the complete process, it is crucial to grasp the uniqueness of this cavitation reactor. This innovation distinguishes between two types of hydrodynamic cavitation devices are static and dynamic. Common static devices, such as Venturi tubes or orifice plates, rely on pressure energy conversion, leading to high energy consumption. Conversely, the dynamic hydrodynamic cavitation device employed here directly utilizes kinetic energy to generate cavitation effects without the need for energy conversion. The rotor inside the device imparts kinetic energy to the fluid, eliminating multiple energy conversion steps, enhancing energy efficiency, and reducing operational costs.

The unique reactor stands out in terms of operation, versatility, scalability, and energy efficiency. Unlike static devices that impart cavitation effects in a single pass, this reactor circulates the material to be processed a thousand times with the same energy input, generating super or intensified cavitation effects. It excels in the transesterification reaction essential for converting oils/fats into biodiesel. While conventional methods require temperatures of 55-60°C and reaction times of 120-180 minutes, this reactor generates high localized pressure and temperature during cavitation bubble collapse, inducing the same reaction without external heating in just 5-10 minutes, resulting in significant energy savings.

Moreover, the reactor's scalability allows for multiple units of varying capacities to be arranged in parallel, seamlessly integrating with existing plant operations. It achieves remarkable biodiesel yields (>99%) through highly effective interphase mass transfer and yields an improved quality of the by-product, glycerin, suitable for industrial applications. The process can be implemented in both batch and continuous modes of biodiesel production, offering production flexibility. With its wide acceptance of various raw materials, it holds potential as an indigenous biodiesel manufacturing solution, promising energy efficiency, reduced costs, and environmental benefits.

Fig. 3 illustrates the inside view of the reactor showing the internal configuration of the stator and the rotor having multiple indentations on the surface for generating intensified cavitation effects. The cavitation reactor comprises a rotor and a stator, with the rotor featuring multiple strategically positioned indentations on their surfaces to generate intensified cavitation effects. The rotor, typically centrally located, is connected to a rotational drive and is covered with surface indentations that disrupt fluid flow, creating turbulence and areas of low pressure as the fluid interacts with these irregularities. The stator, surrounding the rotor, complements its features, matching the contour of the rotor's surface with its own complementary indentations to promote turbulence and guide fluid flow. The space between the rotor and stator forms the cavitation chamber, where recirculation of the material being processed occurs. Material is introduced through an inlet, processed within the cavitation chamber, and exits through an outlet. An integrated control system oversees the reactor's operation, including rotor speed, ensuring optimal conditions for cavitation-driven biodiesel production. This design minimizes energy conversion steps and enhances energy efficiency, making the reactor highly effective for biodiesel production through intensified cavitation effects.

Test Examples:
Proof of concept studies have been carried out as summarized below:
Methodology used:
Esterification
i. The raw oil was esterified to reduce the initial free fatty acid content to below <2%. using the following process parameters: (1) methanol/oil ratio: 70 vol%, (2) H2SO4 concentration: 1.5 vol%, (3) reaction temperature: 60OC, (4) reaction time: 1 h.
ii. The esterified oil was collected through layer separation from the unreacted methanol.

Transesterification
i. The esterified oil was mixed with alcohol and catalyst in the ratio of 16 and 2.5 (w/w)%, respectively.
ii. The solution was cavitated for a time period of 5 min and at ambient temperature at a rotating speed of 2500 rpm.
iii. Upon completion, the reaction mixture was transferred into a separatory funnel and left to stand for 20 min. Once the separation process was complete, two distinguishable layers formed in the separatory funnel were observed, where the top layer was synthesised biodiesel and bottom layer consisted of excess alcohol, glycerine and soap.
iv. The biodiesel was collected, washed and stored.

Properties of the biodiesel obtained

Property Recommended Obtained
Density 0.86 0.863
Moisture <0.15% 0.14%
Soap content Nil Nil
Methanol test Clear solution Clear solution
Cetane number 65 63.4
Acid value 0.55 0.43
Flash point 100-180?C 174?C

Conventional reaction time: 120-180 min, Reaction temperature: 55-60?C
Cavitation based process reaction time: 5-10 min, Reaction temperature: Ambient condition.
, Claims:CLAIMS
I/We Claim
1. A hydrodynamic cavitation-based biodiesel production system, comprising:
an oil pre-heating unit (1), mixer-1 (2), a pre-treatment unit (4), post pre-treatment unit, a mixer-2, a methanol separator/methanol recovery unit (5), a hydrodynamic cavitation reactor (6), a washing tank (8), a separating unit (7), a second separation unit (9), a storage tank (10).
an oil pre-heating unit (1) for the pre-treatment of edible/non-edible oil sources;
a mixer-1 (2) configured for acid-methanol mixing during oil pre-treatment;
a pre-treatment unit (4) configured for both degumming and esterification;
a methanol separator/methanol recovery unit (5) for separating and recovering methanol from the esterification reaction;
a transesterification unit (6) equipped with a hydrodynamic cavitation reactor, configured for the conversion of pre-treated oil into biodiesel;
a mixer-2 (3) for the mixing of sodium hydroxide (NaOH) and methanol, directing the resulting mixture to the transesterification unit (6);
a separating unit (7) for receiving raw transesterified oil, with a bottom layer containing crude glycerin and an upper layer comprising crude biodiesel;
a washing tank (8) configured for the purification of crude biodiesel using warm water;
a second separation unit (9) configured to remove moisture from washed biodiesel through heating;
a storage tank (10) configured for the storage of the separated and purified biodiesel.

2. The system (100) as claimed in claim 1, wherein the pre-treatment unit (4) comprises a degumming and esterification process that involves the removal of phospholipids from the raw oil/fat source and reduces the FFA content by reacting with acid and methanol.

3. The system (100) as claimed in claim 1, wherein the methanol separator/methanol recovery unit (5) includes a distillation column for the efficient recovery of excess methanol, making it available for reuse in the process.

4. The system (100) as claimed in claim 1, wherein the hydrodynamic cavitation reactor in the transesterification unit (6) is designed with adjustable parameters to accommodate various feedstock compositions and processing requirements.

5. The system (100) as claimed in claim 1, wherein the washing tank (8) is equipped with a recycling system that recirculates warm water for multiple washing cycles, reducing water consumption and environmental impact.

6. The system (100) as claimed in claim 1, wherein the storage tank (10) is equipped with temperature control systems to maintain the stability and quality of the separated and purified biodiesel during storage.

7. A method for producing biodiesel from edible or non-edible oil sources, comprising the steps of:
a. pre-heating the oil source in an oil pre-heating unit (1) for efficient pre-treatment;
b. mixing the pre-heated oil with acid-methanol in mixer-1 (2) to facilitate oil pre-treatment;
c. subjecting the mixture to degumming and esterification in a pre-treatment unit (4) for removal of phospholipids and esterification of the oil;
d. separating and recovering methanol from the esterification reaction using a methanol separator/methanol recovery unit (5);
e. performing transesterification of the pre-treated oil into biodiesel in a transesterification unit (6) equipped with a hydrodynamic cavitation reactor;
f. mixing sodium hydroxide (NaOH) and methanol in mixer-2 (3) and directing the resulting mixture to the transesterification unit (6);
g. separating raw transesterified oil into a bottom layer containing crude glycerin and an upper layer comprising crude biodiesel using a separating unit (7).
h. purifying crude biodiesel by washing it with warm water in a washing tank (8);
i. removing moisture from washed biodiesel through heating in a second separation unit (9);
j. storing the separated and purified biodiesel in a storage tank (10) equipped with temperature control systems to maintain its stability and quality during storage.

8. The method as claimed in claim 1, wherein the reduced reaction time of 5-10 minutes in step e is achieved through precise control of cavitation intensity within the hydrodynamic cavitation reactor.

9. The method as claimed in claim 1, wherein the reduction in required reaction temperature from a range of 55-60°C to ambient in step e is achieved through precise temperature control mechanisms within the hydrodynamic cavitation reactor.

10. The method as claimed in claim 1, wherein the >99% yield in biodiesel production in step e is attained by optimizing the cavitation reactor's operating parameters, including pressure and flow rates.