WO2016117991A1

WO2016117991A1 - System for generating bio-diesel from different raw materials having a high lipid content by means of the in situ transesterification process

Info

Publication number: WO2016117991A1
Application number: PCT/MX2015/000006
Authority: WO
Inventors: Jose Martin VELEZ DE LA ROCHA; Omar VAZQUEZ PALMA; Dino Alejandro Pardo Guzman
Original assignee: Velez De La Rocha Jose Martin
Priority date: 2015-01-21
Filing date: 2015-01-21
Publication date: 2016-07-28

Abstract

The invention relates to the production of bio-diesel from wet biomass having a high lipid content, using a process with two main stages, involving hydrothermal carbonisation (HTC) and supercritical in situ transesterification (SC-IST). The wet carbon or "hydrochar" produced by HTC is reacted with ethanol or methanol, not in excess, controlling the residence time, moisture levels, pressure and temperature. A continuous process is established, involving a number of stages such as hydrothermal carbonisation, filtering and supercritical in situ transesterification. This process observes the conditions that provide the best results: in the hydrothermal carbonisation, working with a mixture of 20% solids and at a temperature of 250°C for a time of 45 minutes, and for the supercritical in situ transesterification, working with a molar ratio of 20:1 of ethanol and fatty acids, having a moisture level between 45 and 50%, at a temperature of 275°C, and for a time of 180 minutes.

Description

BIODIESEL GENERATION SYSTEM FROM DIFFERENT RAW MATERIALS WITH HIGH LIPID CONTENT THROUGH THE IN SITU TRANSESTERIFICATION PROCESS

TECHNICAL RESEARCH FIELD

The present application belongs to the alternative diesel production area from other renewable ones, through the application of the on-site transesterification process.

BACKGROUND

Today, the commercialization of biofuels at competitive prices with oil has been blocked due to the lack of technologies capable of processing and converting wet biomass into fuels. Likewise, producing an advanced biofuel or biodiesel from wet biomass that meets the carbon reduction requirements in accordance with "US Renewable Fuel Standard" is difficult if the biomass has to be dried using non-solar methods before fuel transformation. . Taking into account the problem of working with wet biomass, in which a two-step method has been proposed to convert wet biomass to biodiesel through the process of hydrothermal carbonization and transesterification in situ with ethanol and without the use of catalyst. The processes work with a liquid biomass sludge that contains 10-20% of total solids which is reacted with hot water (190-250 ° C) at autogenous pressures to conglomerate the cells in a filterable solid that contains the lipids and It produces a sterile and nutrient-rich aqueous phase. In the second step, the lipids contained in the wet coal or "hydrochar" are converted into biodiesel without having to perform solvent extraction by using the supercritical ethanol method.

In situ transesterification has traditionally been limited to reactions catalyzed with bases. Although large conversions can be achieved at moderate temperatures, subcritically catalyzed in situ transesterification usually requires a large excess of alcohol, is sensitive to water and requires long reaction times. For example, soybean containing 7.4 wt% moisture was reacted at 23 ° C for 8 hours with 180: 1 methane fatty acid methane methanol to achieve 93% conversion of lipids to biodiesel. Later work has shown that if the percentage of humidity is reduced and physical pretreatment to biomass is carried out, high conversions can be achieved in shorter times and with less methanol 9-25: 1 MeOH: AG. The use of methanol still remains higher than commercial oil transesterification, which is usually carried out at 2: 1 MeOH: AG. Excess methanol is usually required to submerge the biomass, with a side effect being the dilution of water present at negligible concentrations.

Recently, microalgae has been investigated as the raw material for subcritical transesterification in situ. Since algae biomass typically contains a higher proportion of fatty acids compared to oilseeds, acid catalyzed reactions, which do not form soaps, are most commonly carried out. It has been found with Chlorella containing 0.7 wt% moisture was reacted at 60 ° C for 6 hours with approximately 105 MeOH: AG and 100 wt% H ₂ S0 ₄ , the conversion balance to methyl esters was reduced by 20% compared to the reactions with dry biomass. When the biomass humidity exceeded 31.7% (dry base) or the water constituted 9.5 wt% of the mixture to be reacted, the transesterification was totally inhibited.

Considering the costs and energy input associated with the drying and processing of biomass before sub-critical in situ transesterification as well as the recovery of excess alcohol after the reaction, the exploration of supercritical alcohols has been chosen as a reaction medium for on-site transesterification (SC-IST). SC-1ST can benefit from reduced costs because it does not require catalysts or recovery and generally has a greater tolerance to raw materials that contain water and fatty acids. Although methanol and supercritical ethanol have been well studied as a means of biodiesel production without the use of catalysts from pure vegetable oils, relatively little work has explored SC-IST. Patil et al. (201 la, b) demonstrated the conversion of lipids to biodiesel found in wet algae using the supercritical methanol method, but MeOH: AG ratios above 1600 were employed. In another work, dry rice was reacted with a 90: 1 MeOH: AG and C0 ₂ molar ratio as a solvent at 300 ° C, but the yield was unsatisfactoryly low (50%) (Kasim et al., 2009). Finally, there have been reports on thermochemical liquefaction of dried algae biomass, as of other raw materials, in supercritical alcohols (Huang et al., 2011; Zhou et al., 2012). From our perspective, liquefaction in alcohol to produce bio-oil and in situ transesterification to produce biodiesel describe the same process. In both cases the yields are - determined after removing the solids from the reaction mixture and evaporation of excess alcohol and in both cases a type of improvement and cleaning is required before the fuel is ready for use. From the literature at our disposal, liquefaction work tends to concentrate generally on previously dried and low lipid raw materials, favoring the production of bio-oils on esters, while qualitatively the products are they identify with the use of GC-MS and ignoring the excessive use of methanol. On the other hand, on-site transesterification work usually applies GC-FID to quantitatively determine the performance of esters, while ignoring other components in raw biodiesel and what precautions have to be taken to remove them. Levine et al. (2010) showed that lipids contained in "hydrochar" (46% humidity) can be converted to FAEE when they are reacted with alcohol. The highest yield of esters (60%) at 275 ° C was reached after 120 min of reaction with 50: 1 EtOH: molar FA ratio.

In some of the biofuel production processes, dry methods are used to extract the oils. This stage of oil extraction is the most intensive in matters of energy consumption. This stage consumes about 85% of the production energy. To eliminate the energy consumption involved in drying, wet processing methods have been explored for the production of biofuels.

Hydrothermal processing, which involves the application of temperature and pressure to biomass in an aqueous medium, assimilates the conversion of old plants into crude oil, coal and natural gas as the reserves on which the world depends today.

Subcritical extraction with water (SCW) or hydrothermal liquefaction (HTL or HTC) is another way to isolate or produce the raw material necessary for the production of biofuels. Water is identified as a benign and non-toxic medium, with selective extraction or reaction capabilities and is a green solvent that is ready and available. The process of converting biomass into HTC takes temperatures between 200-370 ° C and high pressures. The characteristics of the bio-crude or crude extract produced during this process vary depending on the temperature and pressure used. The solubility of organic matter begins to increase rapidly from 200 ° C, and this improved solubility for organic compounds is provided by a single phase homogeneous medium for organic synthesis in subcritical water. The reduction of the dielectric constant makes water the suitable solvent for small organic compounds, as its dielectric constant drops from 80 to 25 ° C to 40 to 200 ° C. Extraction with subcritical water has been demonstrated for the extraction of "mannitol" found in olive leaves, and essential oils of coriander seeds.

In hydrothermal liquefaction and at elevated temperatures, biochemical compounds found in the biomass undergo reactions such as hydrolysis, re-polymerization to create dense energy bio-crude oil, "hydrochar", water-soluble compounds and gaseous products. During this process, the oxygen present in the biomass is removed in the form of water due to dehydration and by decarboxylation in the form of carbon dioxide. The successful liquefaction of whole seaweed was demonstrated by Biller, Brown and Toor at temperatures of 300 ° C or higher to produce energy-dense bio-crude oil. The biggest obstacle to refining bio-crude oil in regular refineries is the high nitrogen content, which requires a special catalyst or processing strategies. In situ transesterification is a process in which the oil or fat contained in the seeds or oleaginous plant fruits, or in adipose tissue of animals is extracted and transesterified in a single step, which implies that alcohol used in the process, in turn, serves as an extractor agent for lipid material and as a reagent in its transesterification.

On-site transesterification has been considered, since the beginning of the biodiesel industry in the eighties of the twentieth century, as an alternative to reduce production costs. Its application eliminates the stage of mechanical extraction or solvent extraction, avoids the processes of refining the oil or grease, and increases the yield of esters from a given mass of seeds, compared to the conventional process that starts from the oil previously extracted.

BRIEF DESCRIPTION OF FIGURES

Figure 1 is a flow chart of the process applied to carry out the transesterification in situ.

Figure 2 represents a diagram of the process and all the components used to carry out the transesterification in situ.

DETAILED DESCRIPTION OF THE INVENTION

In the first stage there is a primary tank (1) in which all the raw material with which it will be worked is received. In the second stage there is a continuous high pressure tubular reactor (2) to carry out the hydrothermal carbonization of the organic matter. In the third stage there is a tubular filtration system (3) by which excess water is removed from the coal obtained. In the fourth stage there are two high pressure continuous tubular batch (4) reactor in which the transesterification will be carried out in situ.

Initially, the primary tap (1) is empty and hermetically sealed, then the microcontroller (6) detects the state and opens the upper gate (5) for recharging raw material and once loaded, the upper gate (5 ) closes again. At this point the lower gate (7) opens to drop the raw material little by little towards the tubular reactor (2), the function of the microcontroller (6) is important since it does not allow the opening and closing of the upper gate (5) and lower gate (7) the pressure inside the tubular reactor (2) is maintained. Since the raw material is inside the tubular reactor (2), the HTC process is carried out in which the organic matter is carbonized. Organic matter is found in a mixture of 20% solids. In order to carry out this process, the reactor temperature is maintained at 250 ° C, which is regulated by four heating bands (8). The high temperatures and the amount of water in the system cause the pressure to rise and be a danger factor in this system. As a safety measure, the tubular reactor (2) has a safety valve A (9) which opens when the pressure exceeds the established limit. The tubular reactor (2) also has a pressure sensor A (10), a temperature sensor A (1 1) and a water level sensor A (12). In the inner part of the reactor there are two endless screws A (13), which give the necessary residence time of 45 minutes to the raw material, in order to carry out the carbonization of the same. The water in the process helps to perform the hydrolysis and carbonization of the raw material. A level of water (14) is always maintained in the reactor that must be regulated. When the water level (14) is below what is required, there is an intake valve (15) to add the water necessary to maintain the desired water level (14). When there is an excess of water, there is an extraction valve (16) to purge the liquid. The outgoing product of the tubular reactor (2) called hydrochar, falls into a secondary tank (19); said tank that has a normally open filling gate (20) and that closes tightly when the microcontroller B (21) detects a filling level of 80%, then the microcontroller B (21) sends to open the emptying gate (22 ) of the secondary tank (19) and the hydrochar goes to a filtration process to remove excess water. In this process the hydrochar falls on an endless screw B (17) to be able to move and give the necessary residence time to the matter to carry out the water removal. Water is filtered through a small mesh (18) where only water can pass and not solid materials.

In the fourth stage, the two batch reactors (4) perform the transesterification in situ. There are two separate batch reactors (4) to help maintain the continuous process. While one reactor is filled with the "hydrochar" material leaving the filtrate, the other reactor carries out the SC-IST reaction.

The hydrochar outgoing from the filtration process must have a humidity percentage between 45-50%. The fourth stage of the process (SC-IST) is carried out with the addition of methanol in a molar ratio of 20: 1 MeOH: FA fatty methanocides. This material enters one of the batch reactors (4) where the process of transesterification in situ is carried out in which the lipids inside the hydrochar are transformed into biodiesel. In order to carry out this SC-IST process, the reactor temperature is maintained at 275 ° C, which is regulated by a heating jacket (23) which each reactor has. The high temperatures and the amount of water in the system cause the pressure to rise and be a danger factor in this system. The temperature, pressure and water level in each reactor are monitored by a pressure sensor B (24), a temperature sensor B (25) and a water level sensor B (26). Each batch reactor (4) has an agitator (27) inside it to keep the reaction mixture homogeneous. In order to carry out the transesterification in situ of the lipids found in the "hydrochar", it is necessary to establish a residence time, in the batch reactors (4), of 180 minutes. The two batch reactors (4) have a conical bottom (28) to help the homogeneity of the mixture and avoid stagnation of the mixture if the reactor has corners. Each tank has in its lower part an extraction valve (29) to be able to carry out the recirculation of the mixture in the tank or for the emptying of the product. As a safety measure, the reactor It has a safety valve B (30) which opens when the pressure exceeds the desired limit. Each batch tank (4) has its own recirculation pump (31) to be able to recirculate the mixture and help maintain homogeneity.

Feeding system: There is a feed and dislocation system for raw material and high-pressure products using pneumatic valves that perform the movement of opening and closing the upper gate (5), lower gate (7), intake gate (20 ), drain gate (22) as the case may be. This system is located at the beginning and end of the tubular reactor (2) for HTC. The established system is designed to feed raw material and withdraw the product minimizing pressure losses in the system. The primary tank (1) and the secondary tank (19) have a microcontroller (6) and microcontroller B (21) respectively that have the function of notifying when each tank is full or lacks raw material / product. When microcontroller (6) / microcontroller B (21) indicates that the primary tank (l) / secondary tank (19) does not contain raw material / product, it sends a signal to the pneumatic valve to open the upper gate (5) / intake gate (20) and allow the filling of the primary tank (1) / secondary tank (19). When the microcontroller (6) / microcontroller B (21) indicates that the tank is full, it will send a signal to close the upper gate (5) / intake gate (20) (stop filling) and the lower gate will open { 1) 1 emptying gate (22) to let the raw material / product pass to the next process. Each primary tank tank (l) / secondary tank (19) has a relief valve A (32) / relief valve B (33) to release the working pressure before the primary tank (1) opens the upper gate (5) and the secondary tank (19) open the drain gate (22).

Claims

What is claimed is:

A continuous process biodiesel generation system through the supercritical reaction of transesterification in situ in which lipids are introduced and biodiesel is obtained; which is constituted by a device for the production of biodiesel that includes a continuous tubular reactor of unique design and a method of continuous processing of four stages from biomass with high lipid content.

2. - The device of claim 1 consisting of: a) A cylindrical tank with conical bottom for the reception and storage of raw material that has a microcontroller for the material inlet and outlet gate and a pressure regulating valve. Used for the supply of the tubular reactor. b) A continuous tubular reactor of unique design that inside is constituted by a pair of endless screws that transport the matter through the reactor giving it the residence time necessary for the hydrothermal carbonization process; outside it has 4 heating bands to provide a uniform and controlled temperature; It also has level, temperature and pressure sensors to control the optimal conditions of the process; it also has a pressure relief valve for safety; a water intake control valve; a water purge valve. c) A cylindrical tank with conical bottom for the reception and storage of hydrochar that has a microcontroller for the material inlet and outlet gate and a pressure regulating valve. Used to supply the filtering system. d) A filtration system to remove excess moisture from the hydrochar, achieving a parameter between 45% and 50% humidity. e) Two batch reactors to carry out on-site transesterification which are constituted in its interior by a stirrer, pressure sensors, temperature and fluid level, a pressure regulating valve for safety, outside a three-way valve for recirculation of material and final product discharge, a material recirculation pump and a heating jacket that covers the entire tank.

3. The method for the generation of continuous process biodiesel mentioned in claim 1 and consisting of 4 steps described below: a) Receipt of raw material: The raw material to be used must be crushed and can be seeds or fruits of oil plants and fatty tissues of animals, in theory it could be any organic material that has a high lipid content. In this stage, the raw material with which the process will be fed is collected and prepared. b) Hydrothermal carbonization: at this stage the raw material is deposited inside the tubular reactor where a pair of endless screws move the material through the reactor and a mixture of 20% solids is generated, subjecting it to a temperature of 250 ° C and a residence time of 45 min, whereby the organic matter is hydrothermally carbonized to destroy its cells and free and exposed the oil contained inside. c) Filtering: at this stage the removal of excess water is performed using an endless screw that pushes the material through a maya filter that does not allow the passage of solids with what is achieved by obtaining hydrochar with a 45 % to 50% humidity. d) On-site transesterification: At this stage the hydrochar is deposited inside a reactorbatch in which methanol is added to obtain a molar ratio of 20: 1 MeOH: FA methanol: fatty acids. The mixture is then subjected to a temperature of 275 ° C and a residence time of 180 min. With which transesterification is achieved and with it the transformation of oil into biodiesel. In this process there is a stirrer and a recirculation system to achieve homogeneity in the mixture.

4. The system of claim 1 of biodiesel production that does not require an oil extraction stage or process.

5. The system of claim 1 of biodiesel production in aqueous medium and without the need for a pretreatment of drying.

6. The continuous tubular reactor mentioned in claim 2b which in its design contemplates a square shape whose vertex is at the lowest point and its edges form a 'V with which an impregnation of matter in the water is achieved and that it allows a runoff of the same at the same time before leaving the process, which conserves the temperature and pressure with variations of less than 5% at and water reuse is achieved by reducing pressure and temperature losses.

7. The lipids with which the device of claim 1 is fed, which may be any organic material containing a high lipid content.