WO2014019043A2

WO2014019043A2 - Simultaneous conversion method for sugar cane bagasse using uhtst reactors

Info

Publication number: WO2014019043A2
Application number: PCT/BR2013/000275
Authority: WO
Inventors: Jonas NOLASCO JUNIOR; Sindelia FREITAS AZZONI; Carlos Eduardo VAZ ROSSEL
Original assignee: Centro Nacional De Pesquisa Em Energia Em Materias - Cnpem
Priority date: 2012-08-01
Filing date: 2013-07-31
Publication date: 2014-02-06
Also published as: BR102013006389A2; WO2014019043A3

Abstract

A method and equipment are disclosed for simultaneously converting sugar cane bagasse using continuous UHTST reactors, with superheated liquid water for the bagasse pre-treatment and hydrolysis process. The pre-treatment process disclosed comprises 2 phases that are sequentially operated in different conditions of dwelling time, temperature and pressure, optimised to maximise the preservation of the monomeric or oligomeric sugars of each of the bagasse fractions, hemicellulose and cellulose, and consequently to minimise the formation of inhibiting products. The heating and cooling systems, both before and after pre-treatment, were also designed for rapid operation, for a duration of less than a minute and a half or even of fractions of seconds.

Description

"Process for the simultaneous conversion of sugarcane bagasse using UHTST REACTORS"

APPLICATION FIELD

Conversion of biomass, preferably sugarcane bagasse, to release glucose monomers and oligomers for biofuel production and biosynthesis in general. The present invention relates to the

complete process utilizing UHTST continuous reactors and heating and cooling systems for converting sugarcane bagasse into their structural units of sugar, whether monomeric or oligomeric.

BACKGROUND OF THE INVENTION

The deconstruction of sugarcane bagasse, for example, by hydrolysis processes, is difficult to perform due to the close association that exists between the three major polymeric components of biomass, ie due to their high degree of association. For this reason, several pretreatment processes are being studied and, among the most promising, are those of steam explosion or those that use water as a reagent (RAMOS, 2003; GÁMES et al., 2006; CUNHA 2001; PITARELO , 2007).

To know the state of the art of steam explosion technology and other processes using water as a pretreatment reagent, surveys were performed:

In the patent ES8706829 biomass is treated with steam at 200-250 C in a sealed reactor for 2-20 min, that after treatment, the system temperature is decreased gradually to ambient. However, it was noted that the abrupt rupture of the fibers, which did not occur in this process, generated better results for subsequent treatments.

Already in 1928 a wood vapor explosion apparatus, US1, 655,618 was patented. The report describes high pressure and temperature conditions with consequently rapid depressurization. Since then, several other studies have been conducted to improve this type of process.

CA1096374 and CA141376 describe the pretreatment reactor and the steam explosion process of lignocellulosic matter, which in 60 seconds raises the pressure in the range of 28.1-49.2 kg / cm ² at a temperature of 180-240 ^S C, which subsequently has a rapid depressurization and lowering of temperature by being exposed to atmospheric air. Also in the last document is the glucose production stage by impregnating the cellulose with acid solution.

US2002164730 protects a process that is quite Full production of ethanol, comprising pretreatment by steam explosion, the biomass originating from agricultural residues at low temperatures (200- 220 ^and C), high pressures and treatment times larger (5 to 10 minutes) . The inventors claim that these conditions give rise to better glucose recovery rates.

The patent filed in Brazil number PI0801352 brings a steam blasting equipment, mainly of wood. In it a centrifuge helps to increase the pressure in the reactor, which reduces the energy consumption, because less steam is added to the system for high pressure.

Also in US20120 11514 there is a description of a process that does not require the presence of acid catalysts in the bagasse steam blast treatment, as the acetic acid itself generated during pretreatment, through glucose degradation, assists the reaction. Specific conditions of temperature (170-220 ^S C), pressure (100-320 psig), and time (5 to 90 minutes) allow catalyst removal. As an additional step there is a purge that removes water soluble compounds and volatile chemicals.

US 6,419,788 conducts a steam blasting process of lignocellulosic matter, primarily wood, under known conditions, but which is subsequently treated with alkaline pH (8-13) hot water containing dissolved oxygen. Wash water removes lignin, hemicellulose and inhibitors from the hydrolysis step.

There are also a variety of patents (US 5,125,977, US 5,424,417, US 5,503,996, US 5,705,369, PI9005762, WO2000019004, US20100276093, CA1267407 and CA1282777) using bagasse steam blast for the production of products other than ethanol such as for example paper. In most of the processes described in said documents during or after the explosion of the material it is treated with alkaline solutions to generate the pulp that will give rise to the paper.

Of the processes involving the use of hot water, one of the novelties is the presence of rapid cooling, which decreases the amount of inhibitors in the process and preserves the sugars extracted from steam blast treatments. There are several priorities regarding the UHTST process in biomass and synthetic cellulose, however, no industrial scale equipment was found to perform such activity in the pretreatment and hydrolysis of sugarcane bagasse.

Sasaki et al., 2003, came up with a study of the degradation of sugarcane bagasse by hydrothermal treatment. According to the authors, this type of biomass fractionation was "cleaner" compared to other existing treatments, as the solvent used was water. The experiment was conducted on a laboratory scale, in which bagasse fed a steel tube and mixed the water introduced through two HPLC pumps. The experimental conditions were temperatures of 200-230 ⁹ C, for extraction of hemicellulose and lignin and 230-280 C for removal of the pulp, at a pressure of 15MPa. The liquid phase was rapidly cooled and analyzed. The process allowed approximately 90% of the biomass to be solubilized. It is noted, therefore, that since the year of publication of the article, studies were conducted with regard to this type of treatment. The study makes no mention of residence times or the recovery and preservation of sugars.

Subsequently in 2004, Sasaki et al., Came up with a new article on synthetic cellulose conversion, by using supercritical water at a temperature of 320-400 C ^2, 25MPa pressure and residence times from 0.02 to 13, 1 sec. Distilled water fed a preheated HPLC pump, which was later mixed with cellulose, which was introduced into the reactor. After the reaction, the mixture was rapidly cooled to 60 ² C. The reactors used in this experiment were from 0.03 to 5.27 cm ³ and the substrate used was pure cellulose, that is, it was far from the conditions found in the industry.

WO2012060767 and JP2003212888 are intended to separate cellulose and / or oligosaccharides from solid biomass with water under severe conditions, such as temperatures greater than 250 ^S C and residence times of 1, 5 and 1, 0 seconds respectively. and the extracted phases are rapidly cooled. The first process presents a description of possible equipment to be used, however, does not bring the system design, and the experiments take place on a laboratory scale, using pine as biomass and yields of 35% glucose recovery. In the second case is shown a diagram with the necessary configuration to perform the process, however, the available examples involve the degradation of crystalline cellulose, a situation that does not represent the conditions found in the industry.

And yet PI0706024, describes process and equipment of biomass hydrolysis, previously minced and placed in contact with water, optionally containing ethanol (2 10%) under high temperature conditions (C ² 140- 180 and 240-280 C for ² hemicellulose and cellulose degradation, respectively) and pressure in a number of 4 + n or 3 + n pressure reactors, where the various heating, cooling, and other processes can occur. simultaneously. The cooling step is by evaporation of water. The process can save up to 60% energy with a saccharide yield of approximately 40%. In this case an equipment for the treatment of biomass is outlined, however, much differs from that intended to protect and does not yet bring a rapid cooling system of the mixture.

Patent CN101613377 outlines a biomass degradation system through its pretreatment and hydrolysis, mainly wood, in reactors with water under supercritical (350-400 ^fi C), and subcritical (200-300 ^a C) conditions, in sequence. In both situations the respective chillers (100-200 ^to C and 15-50 ^to C) from each reactor lower the system temperature. In the present case there is no discussion about the residence time of the biomass in the reactor and still focuses on the biomass disruption to glucose rather than xylose / glucose removal.

Document JP2009261275 brings a preheating, reaction and cooling system through the use of three reactors for each step, which, according to the inventors, allow a not so abrupt temperature decrease in each unit, which decreases its costs. In the first step, the mixture biomass and water are preheated to 70-120 ^fi C with recycled steam cooling step, and is transported to the second stage, which occurs treatment with hot water at 140-200 C for ⁸ extraction of C5 or 240-280 ^to C for cellulose extraction. In the last three tanks is decreasing temperature to 140-180 C by evaporation. The biomass and solution are separated and solid matter can be returned to the system again. A saccharide yield of approximately 40% is obtained. The patent describes a process that will take at least 1 minute for each step to occur and has no specific equipment for solid and liquid phase separation.

Process CA2750754 features a hydrothermal treatment in which water and biomass are extruded countercurrent and the liquid phase is sent to an enzymatic hydrolysis unit, while the solid phase is cooled with lower temperature liquid water to stop hemicellulose degradation, and which is also subsequently sent to the enzymatic hydrolysis unit. The process involves a solid and liquid phase separation step for both extractions and a process water recovery step for energy saving. In this system the reactor is in a vertical position, which can cause matter loss, since the bagasse, for example, is a light biomass, making it difficult to control its rise. Still the process takes minutes to occur, for example, in the first Pretreatment step, extrusion occurs 3-10 minutes.

The process WO2011091044 claims a lignocellulosic biomass treatment process where in a first reactor pretreatment, hot water and the cellulosic matter are brought into contact at a temperature of 180-260 ⁹ C, pressure of 50-110 bar and at time 1-10 min. After this step liquid / solid separation occurs and xylose in solution is cooled. The other phase is subjected to hydrolysis under conditions ^S 275-450 C, 200-250 bar pressure and 1-45 s residence time. The products are separated and cooled. In the two power stages can be added C0 ₂ as well as in both cooling steps acid may be optionally added. Cellulose recovery from biomass reaches 60% yields, with glucose conversions up to 90%. The process resembles many others disclosed herein, except for the addition of water and C0 ₂ in supercritical conditions, and acid at the beginning of the experiment, however the document does not disclose a proper equipment for carrying out the process. Technology conditions make the process more expensive, which justifies its use for the production of high added value products.

The UHTST process concept can also be applied to broths used in fermentation to obtain ethanol and is widely used in the food industry but with the purpose of thermally inactivating contaminants while preserving maximum nutrients.

It is clear, therefore, that the concept of UHTST treatment is well studied and targeted for the industry, however, no equipment capable of bringing the expected results has been effectively introduced in the market for biomass conversion.

SUMMARY OF THE INVENTION

The present invention describes the process for converting sugarcane bagasse using UHTST continuous reactors using superheated liquid water for the bagasse pretreatment and hydrolysis process. The proposed pretreatment process is conducted in 2 phases that operate sequentially under different conditions of residence time, temperature and pressure optimized for maximum preservation of monomeric or oligomeric sugars of each of the bagasse hemicellulose and cellulose fractions and consequently minimal formation of inhibitory products. The pre-treatment and pre-treatment heating and cooling systems are designed to be conducted equally quickly, lasting less than one and a half minutes or even fractions of seconds.

The temperature range is wide up to 350 ^to C depending on whether or not chemicals are capable of creating synergy with heat treatment. Effective residence times during pretreatment are less than 1 minute and may reach fractions of seconds. The entire process involving reaction, cooling and transfer to subsequent steps is conducted aseptically, by not contacting the material with outside air to avoid contamination. Process steam consumption is less than 20kg / TC while water consumption is less than 4kg / kg of treated bagasse, and with this water consumption the concentration of fraction C-5 from hemicellulose hydrolysis is 75.5g. / L whereas the concentration of the C-6 fraction from cellulose hydrolysis is 120g / L. The evaporative cooling system adopted provides thermal regeneration, concentration and rapid cooling in order to preserve the released sugars.

A drawback of the prior art is that the pretreatment processes generate low concentration hydrolysates (<20g / L) and are energy intensive for concentration at the levels obtained by this technology.

Another drawback of the prior art, overcome by the present invention, is that the modules used for the pretreatment do not have a good matter transfer dynamics when it is intended to increase the residence time of the biomass in the reactor. such a varied flexibility of said times of residence.

DESCRIPTION OF THE INVENTION

The process described herein utilizes superheated water at a temperature and pressure range of 280 ^fl C / ² C 64,5barg 350/161, 5barg without the use of chemicals, acids or enzymes, carried out in two stages.

Overheated water under the conditions of this project has excellent properties, such as high solvency capacity, including organic substances, high reactivity and very low viscosity.

The process is designed to occur in 2 phases where reactors are designed to separately extract and hydrolyze hemicellulose by releasing sugars of 5 carbon atoms and hydrolyze cellulose by releasing sugars of 6 carbon atoms. Both process steps are conducted with the UHTST concept, meaning Ultra High Temperature Short Time, ultra-fast thermal processes that are conducted at elevated temperatures. This process class is widely used in the food industry in sterilization and pasteurization processes with the mutual goal of eliminating microbiological contaminants and preserving food nutrients. In the case of pretreatment From the bagasse, the heating and cooling steps are also extremely fast to prevent sugars from undergoing thermal degradation reactions, thus preserving them, thus preventing the release of organic acids and other inhibitor products to the subsequent process steps.

Hydrolyzed broths are sent to evaporative cooling vessels ensuring instant cooling to safe temperatures to prevent such thermal degradation reactions. Evaporative cooling vessels also ensure thermal regeneration and hydrolyzed broth concentration and are sized for minimal sugar carry-over. Optimum amount of overheated water for the pretreatment process can be used without concern for excessive dilution of sugars in the resulting hydrolyzed broths as the added water will be removed during evaporative cooling and reused as steam.

The reactors used are pluggable tube modules which, together with varying pump speed, allow the pre-treatment residence time to be varied over a wide range as required for optimization. By presenting high pressures, decompression at the exit of ^the reactor 2 desestrutu mechanical assembly gives biomass feed with consequent increase in its specific surface, which contributes to increase the efficiency of the subsequent enzymatic reaction in the case of this reaction is required.

The steps of the hemicellulose and cellulose pretreatment and hydrolysis process are designed to occur in separate reactors and also separately extracting the C-5 and C-6 rich hydrolyzed broths in order to provide more flexibility to the subsequent process. With this configuration these streams may be processed separately or premixed for joint processing depending on available technology which is not the subject of this invention.

The system of the present invention therefore has the advantages of maximum specific surface area for the enzymatic reaction together with maximum hemicellulose removal, maximum cellulose preservation (> 99%), maximum pentose preservation (> 99%) and minimal production. of inhibitory products.

DESCRIPTION OF THE FIGURES

Figure 1 - UHTST PRE-TREATMENT AND SIMULAN CONVERSION OF CANE bagasse in the extraction configurations of C-5, C-6 without enzyme use.

Figure 2 - Diagram of individual reactor assembly for each process step. DETAILED DESCRIPTION OF THE INVENTION

Bagasse (1) is fed to a mill (2) in which it is processed, here it is noteworthy that processed characterizes the reduction and uniformity of its particle size distribution. Said treated bagasse (1) is discharged into a helical conveyor (3) where it receives a small amount of hot water (4) for swelling and formation of the bagasse sludge (5), making the bagasse pumpable. The helical conveyor discharges this bagasse sludge (5) into the pump suction (6) which will feed the first reactor module formed by panel pluggable standpipe assembly (7, 8, 9, 10) through the connections (11 , 12, 13, 14) designed to achieve residence times within the range of 0.5 second to 80 seconds. Said tubes allow that, if the reaction does not occur completely within a certain residence time, previously stipulated, the raw material, preferably bagasse, may still remain in contact with hot water for a longer time. Water superheated to 250-300 C and 40-90barg (15) feeds this first module in co-current with the sludge residue. At the end of the tubular section of the outlet tube (10) the sludge (43) finds a perforated mesh of 400 to 600 mesh (44) which will be responsible for separating the liquefied hemicellulose (C-5 sugar rich liquor) from the lignocellulosic solid. The C-5 high sugar liquor (45) is sent to a set of evaporative coolers (16-21) whose function is to promote instant cooling, where instantaneous refers to cooling performed preferably in milliseconds; liquor concentration; and thermal and water regeneration. This can be achieved by using multiple stages in series. Shown here is a set of 6 stages. The cooling temperature will vary depending on the number of stages used in the system. The greater the number of stages, the greater the thermal regeneration. At the end of cooling the outlet liquor (46) will be rich in C-5. In addition, stream 22 can ideally be used for energy integration in parallel processes such as the 1G sugar and ethanol production plant. Stream 23 represents replacement water for the process.

The lignocellulosic material (24) from the perforated screen (44) proceeds to the suction of the pump (25) which feeds the second reactor module. The second reactor module is also comprised of panel pluggable standpipe assemblies (26-29) through connections (48 to 51) designed to achieve residence times within the range of 0.5 second to 80 seconds. Overheated water (30) at 300-370 ^to C and 90-220 barg feeds the second module in co-current with lignocellulosic sludge (24). At the end of the tubular section of the outlet tube (29) the lignocellulosic sludge (31) encounters a 400-600 mesh perforated mesh (32) which It will be responsible for the separation of the sugar-rich C-6 liqueur (33) from the lignocellulosic lignin-rich insoluble solid material (34). The C-6 high sugar liquor (33) is shipped to an evaporative cooler system (35-40) whose function is to promote instant cooling, where instantaneous refers to milliseconds, liquor concentration and thermal and water regeneration. . This can be achieved by using multiple stages in series. The greater the number of stages, the greater the thermal regeneration. Shown here is a set of 6 stages. At the end of cooling the outlet liquor (47) will be rich in C-6. In addition, stream 41 can ideally be used for energy integration in parallel processes such as the 1G sugar and ethanol production plant. Stream 42 represents replacement water for the process.

The reactor is designed with modules with lead times of 1, 5s, 4s, 12s and 40s. These modules can be used in combination or separately and varying the reactor feed rate achieves a wide range of treatment times ranging from 0.5 to 80 seconds.

Figure 2 represents each module that is formed by a set of standby reactors with different residence times, which can be easily configured by choosing panel connections, where the inputs (52, 53, 54 are available). , 55) and outputs (56, 57, 58, 59) of each reactor. Additionally the tubular reactor has excellent characteristics for reactions involving solids because it enables easy cleaning and no energy consumption in the mixture.

EXAMPLE 1

40 kg of raw bagasse with 50% humidity / 80 kg of water (1) is fed to a mill (2) and processed to a particle size of less than 1 mm. Said pulp is discharged into a screw conveyor (3) which receives small amount of hot water (4) at approximately 100 C. The ^S auger that discharges pulp sludge (5) in the suction of the pump (6) , which will feed the first module of reactors formed by a set of standby tubes (7, 8, 9 and 10) with residence time of 0.5 to 80 seconds. 80 kg of overheated water at 300 ² C and 88 barg (15) feeds this first module in co-current with the pomace sludge. At the end of the tubular section of the outlet tube (10) the sludge meets a perforated 400 mesh screen (44) which will be responsible for separating the liquefied hemicellulose (C5 sugar rich liquor) from the lignocellulosic solid. The C-5 high sugar liquor (43) is shipped to a set of 6 evaporative coolers (16 to 21) whose function is to provide instant cooling to 70-80 ^s C and 75.7g / L in milliseconds. Additionally the chain (22) provides 38 kg of water at 286 C. The ^second stream (23) represents 42 kg of makeup water for the process. The liquor at the end of the last stage (45) has a C-5 sugar concentration in the order of 75.4 g / L and a temperature of 80 ² C.

Lignocellulosic material (24) from the perforated web is fed to the pump suction (25) feeding the second reactor module (26, 27, 28, 29) with residence time of 0.5 to 80 seconds. 80kg of overheated water (30) at 350 ^to C and 170barg feeds the second module in co-current with lignocellulosic sludge (24). At the end of the tubular section of the outlet tube (31) the lignocellulosic sludge encounters a 400 mesh perforated mesh (32) which will be responsible for separating the C-6 sugar rich liquor (33) from the lignocellulosic lignin rich insoluble solid material (34). The C-6 high sugar liquor is shipped to a set of 6 evaporative coolers (35 to 40) whose function is to provide instant cooling to 65-80 ^s C and 119.5g / l in milliseconds, liquor concentration and regeneration. thermal and water The chain (41) has 46 to 300 kg of water ^S C. The stream (42) represents 34 kg of makeup water for the process. The liquor at the end of the last stage (46) has a C-6 sugar concentration of 119,5 g / L and 75 ^S C.

The process steam consumption is 0.1 kg steam / kg pretreated bagasse resulting in 24 kg steam / TC. This low steam consumption can be absorbed by sugarcane processing units without major energy optimization efforts at the units. The use of multiple effect evaporative cooling in conjunction with the energy integration of modules 1 and 2, provides zero vapor consumption in the first module. This fact results in additional possibilities for energy optimization when implementing a biomass conversion process in sugarcane processing units, as these two energy-rich streams can be used in the process of processing units and contribute to the reduction of consumption. process steam generator. Total water consumption is 3.8 kg water / kg pretreated bagasse, 2.1 kg / kg in the first module and 1.7 kg / kg in the second module.

Claims

1. A process for the simultaneous conversion of sugarcane bagasse using UHTST REACTORS, which comprises a conveyor (3), wherein said conveyor will be fed with processed biomass and overheated water; Suction Pump (6 and 25) that will be fed with bagasse sludge; Connectable Standby Tubes (7, 8, 9, 10, 26, 27, 28 and 29) fed by said suction pump, wherein said pipes allow residence time between 0.5 to 80 seconds; Perforated Screen (44 and 32), wherein said Screens have a Perforation of 400-600 Mesh, preferably 400 Mesh, and separate liquor from solids, derived from said connectable tubes; Set of at least 2 Evaporative Chillers, preferably 6 Evaporative Chillers, (16, 7, 18, 19, 20 and 21) (35, 36, 37, 38, 39 and 40) for each process step, wherein said chillers comprise vapor recycling for process, cooling and liquor concentration, wherein each step comprises 2 steps, wherein one step comprises C-5 sugar recovery and another step comprises C-6 sugar recovery.

Process for the simultaneous conversion of sugarcane bagasse using UHTST REACTORS according to claim 1, characterized in that the processed biomass comprises sugarcane bagasse with reduced and uniform mill size distribution (2).

A process for the simultaneous conversion of sugarcane bagasse using UHTST REACTORS according to claims 1 and 2, characterized in that the sugarcane bagasse that will feed the mill (2) is 50% crude bagasse. moisture.

Process for the simultaneous conversion of sugarcane bagasse using UHTST REACTORS according to claim 1, characterized in that the conveyor (3) is preferably of the helical type.

5. PROCESS FOR SIMULTANEOUS CONVERSION OF

SUGAR CANE PUMP USING UHTST REACTORS according to claim 1, characterized in that the suction pump (6) and (25) receive lignocellulosic matter sludge from the conveyor (3) and perforated screen (44), respectively. .

A process for the simultaneous conversion of sugarcane bagasse using UHTST REACTORS according to claim 1, characterized by the pluggable standpipes (7, 8, 9 and 10); receive lignocellulosic sludge and overheated water at 300 ^{s and} 88barg

A process for the simultaneous conversion of sugarcane bagasse using UHTST REACTORS according to claim 1, characterized in that the connectable standby tubes (26, 27, 28 and 29) receive lignocellulosic sludge and overheated water. 170barg C and 350 ^s.

Process for simultaneous conversion of sugarcane bagasse using UHTST REACTORS according to claim 1, characterized by the evaporative coolers (16, 17, 18, 19, 20, 21, 35, 36, 37, 38, 39 and 40) comprise instantaneous cooling, wherein said instantaneous cooling preferably occurs within milliseconds.

9. Simultaneous conversion of sugarcane bagasse using UHTST REACTORS, characterized in that it contains a conveyor (3); Suction Pump (6 and 25); Attachable Hold Tubes (7, 8, 9, 10, 26, 27, 28 and 29); Perforated Screen (44 and 32); Set of at least 2 Evaporative Chillers, preferably 6 Evaporative Chillers, (17, 18, 19, 20, 21) (35, 36, 37, 38, 39 and 40).

Equipment for simultaneous conversion of sugarcane bagasse using UHTST REACTORS according to claim 9, characterized in that the conveyor (3) is preferably of the helical type.

Equipment for the simultaneous conversion of sugarcane bagasse using UHTST REACTORS according to claim 9, characterized by evaporative coolers (16, 17, 18, 19, 20, 21, 35, 36, 37, 38, 39 and 40) comprise instant cooling.