Title of Invention

A PROCESS FOR PRODUCTION OF ETHANOL FROM SWEET SORGHUM / SUGARCANE

Abstract

This invesntion relates to a process for production of ethnol from stalks of weet sorghum and sugarcane. The process involves trashing of feedstock into fibers, subjecting the fibrized feed stock to thermopermeation by mixing with solubilising agent, extraction of juice, partial concentration of juice to 18 to 78% w/w/, subjecting the partially concentrated juice to continuous fermentaition using 1 to 6 frementers and a ywast strain of Saccharomyces cerevasiae, deyeasting the supernatant fermented mash and subjecting to distillation followed by intoduction into molecular dehydration system to remove traces of water to obtain ethanol.

Full Text

FORM 2 THE PATENTS ACT, 1970 (39 of 1970) COMPLETE SPECIFICATION (Section 10; rule 13) TITLE A PROCESS FOR PRODUCTION OF ETHANOL FROM SWEET SORGHUM SUGARCANE APPLICANT PRAJ INDUSTRIES LIMITED of Praj House, Bavdhan, Pune-411021, India, an Indian company GRANTED The following specification particularly describes the nature of this invention and the manner in which it is to be performed:- 17-10-2005 Field of Invention This invention relates to a process for production of ethanol from sweet sorghum sugarcane. Prior Art Ethanol (ethyl alcohol) also known simply as alcohol is widely used for not only drinking but also various industrial purposes. Conventionally, ethanol is produced by fermentation wherein molasses is generally used as the starting raw material. A part of molasses is first diluted with hot water so that its sugar content becomes almost 15-wt/v%. Then a nutrient is added to adjust pH and the mixture is subjected to sterilisation, cooled and then inoculated with yeast fungus and cultured for about 2 days to prepare a seed yeast. The remainder of said molasses is diluted with hot water so that sugar content becomes about 25-w/v% and the aforesaid seed yeast is added to it. The mixture is subjected to fermentation at about 30 degree C for 4 days, obtaining broth containing about 13 vol% alcohol. Yeast is removed from thus obtained alcohol broth and the broth is then distilled to obtain ethyl alcohol. A drawback of the above conventional method of producing ethyl alcohol is that reaction speed is slow and fermentation is time -consuming. This results in low productivity. Another drawback of the above conventional process is that yeast concentration being low to the extent of 3-4 g/l; a large capacity fermenter is needed in order to produce alcohol in desired quantity. Still another drawback of the above process is that the by¬products produced retard the reaction speed, which necessitate reduction in the concentration of product alcohol. Further, drawback of the above process is that it has high requirement of energy. Still further drawback of the above process is that it requires relatively large volume of fresh water. Yet further drawback of the above process is that it generates relatively large volume of polluting-effluents, and such the process is not eco-friendly. US patent no. 4,562,154 discloses a continuous alcohol manufacturing process, which uses yeast. The process involves use of three types of yeast, in three different fermentation zones and each type of yeast having a different performance property. One type of the yeast used is a conventional yeast having an alcohol producing activity (yeast AV, the second type of yeast (Yeast B), disposed before the zone of Yeast B has also alcohol producing actively but is superior in sugar resistance as compared to yeast B and a yeast C disposed after zone of Yeast B, which has alcohol producing property and is superior in alcohol resistance as compared to yeast B. The fermentation by yeast A, produces ethanol and effluent liquor which is introduced into second fermentation zone which converts further quantity of sugar contained therein into ethanol and a second effluent and sugar, which is introduced into third fermentation zone, which converts the additional quantity of sugar contained therein into ethanol. US patent 4,886,751 discloses an improved process for the production of ethanol through molasses fermentation, wherein a stream of fermentation liquor with an ethanol content of 3-7% by weight and a content of fermentable material less than 2% by weight, is continuously withdrawn from the fermenter. The stream is separated by centrifugal separation into two streams namely a yeast enriched stream and yeast free stream. While the yeast-enriched stream is re-circulated into the fermenter, the yeast free stream is subjected to primary distillation to obtain ethanol enriched top stream and a residual liquid stream. A part of the residual liquid stream is re¬circulated to fermenter and remaining part is subjected to secondary distillation for stripping off remaining alcohol contained therein. The process has the advantage of short residence time of 4-10 hours for the fermentation of the liquor in the fermenter. US patent 4,560,659 discloses a process of ethanol production from fermentation of sugar cane by using yeast. In the known industrial process for extraction of sugar from the sugarcane, it is a known fact even after extraction of sugar, the sucrose still remains, principally in the thin walled parenchyma storage cells in the rind of sugarcane stalks. The process disclosed in the aforesaid US patent, involves use of sugarcane stalks in average size of 0.25 cm to 4 cm to which water is added. The ratio of cane to water is kept in the range of 1:1.4 to 1:1.17 and temperature is raised to 95 degree C to 110 degree C for 5 to 10 minutes and then cooled to 28 degree C to 35 degree C at which inoculum of fermentation micro-organism is introduced, keeping pH between 4 to 7. During fermentation, sucrose starts accumulating in the solution as it migrates by diffusion from parenchyma cells. After fermentation is complete converting sugar into ethanol and carbon dioxide, ethanol is separated by sieving and applying pressure to extract sucrose entrapped within sugarcane pieces. The ethanol is ultimately recovered by filtration and distillation means. A drawback of the processes disclosed in the above patents is low sugar extraction Another limitation of the processes disclosed in the above patents is more energy and water consumption - Still another limitation of the processes disclosed in the above patents is low yield of ethanol As is apparent from the above brief description of the prior art, the processes known in the art have focussed on the extraction of sugar from sugarcane by conventional milling and the fermentation of sugarcane stalks (after extraction of sugar) by yeast. However, the extraction of sugars by process other than conventional milling and then using the sugar thus obtained for the purposes of ethanol production is not known in the art. Unlike sugar manufacture, ethanol production from sugarcane or sweet sorghum requires high efficiency extraction of sucrose along with glucose, fructose and additional sugar from cellulosic pulp and other non-fermenting solids e.g. starch and other carbohydrate polymers. OBJECTS OF PRESENT INVENTION The primary object of the present invention is to propose a process for ethanol production from sweet sorghum or sugarcane by fermentation using a novel strain of yeast. Another object of the present invention is to propose a process for ethanol production from sweet sorghum and sugarcane wherein the process has higher yield by 1 to 2% than conventional process. Still another object of the present invention is to propose a process for ethanol production, which has 20 to 40% less energy consumption than conventional process. The process requires low steam consumption of 5.2 to 5.5 kg per litre of ethanol as compared to 6 to 7.0 kg/I in case of conventional process. Further object of the present invention is to propose a process for ethanol production wherein the process generates lower volume of effluents to the extent of 1 to 2 litres per litre of ethanol as compared to effluent of 10 to 14 litres in conventional process. The process of the present invention further reduces the effluent generation to zero level by way of bio-composting using self-generated press- mud from thermo-permeation step of the process of the present invention. Still further object of the present invention is to propose a process for ethanol production wherein there is very low requirement of fresh water. The process requires 0.5 to 0.6 litre of fresh water for every one litre of ethanol production as compared to 5 to 6 litre of water for one litre of ethanol production as required in the conventional process. Yet further object of the present invention is to propose a process, which is self-sufficient in its energy requirements, by using baggase as boiler fuel that provides more than the energy required for generation of steam and electricity required for the process and the plant. Still further object of the present invention is to propose a process, which is capable of generating surplus electricity at the capacity of 60,000 or more litres per day ethanol production. Statement of Invention According to this invention there is provided a process for production of ethanol from sweet sorghum/ sugarcane comprising: ( a ) preparing fine fibers of the stalk of the feedstock; ( b ) extracting sugar from the fibrized feed stalk; ( c ) clarifying the juice in a conventional manner; (d ) concentration of juice to 18 to 78% by evaporation by any of conventional methods; (e) subjecting the concentrated juice to continuous fermentation by yeast at a temperature of 30°C to 33°C, maintaining sugar concentration during fermentation in the range of 14 -20% and segregating the yeast; (f) distillation of the de-yeasted fermented mash; and (g ) removing the traces of water by molecular dehydration. Characterized in that :- (a) said extraction of sugar from the fibrized feed; stock is carried out by:- (i) subjecting the fibrized feed siock to thermopermeation comprising soaking the fibrized feed stock in a solubilising agent at a temperature of 40°C to 85°C in a moving bed reactor; wherein solubilising agent is a mixture of fresh water and juice recycled from sugar extraction mills wherein the solublising agent is taken in quantity 40 to 50% by weight of feed stock and wherein the resident time for thermopermeation is 10 to 25 minutes; (ii) adjusting pH of the mixture by adding acicl /alkali so that pH is between 5 to 6.5; (iii) adding enzyme at a temperature of 65-7p)°C in the dosage of 0.005 to 0.02% by weight of feedstock; and (iv ) feeding treated feedstock and extracting sugar by 2 to 5 sugar extraction mills. (b) press mud generated from the impurities during said concentration is mixed with effluents obtained from distillation for the purposes of bio-composting; (c) hot condensate water from evaporator is recycled to moving bed reactor for thermopermeation; ( d ) yeast used is Saccharomyces cerevasiae which forms floes by gravity and settles down in a continuous gravity settler and floes of yeast thus formed are segregated and recycled to fermentation process enabling faster fermentation within 10 to 22 hours; and ( e ) the effluents generated from distillation are reused fortTeheating the fermentation medium and cooled effluents are used for diluting the syrup to desired concentration. Description of Figures The process of the present invention is illustrated by drawings. The drawings are not intended to be taken restrictively to imply any limitation on the scope of the process. In the accompanying drawings: Figure. 1: - shows the flow chart of the process of the present invention. Figure. 2: - shows the schematic presentation of fermentation plant. Description of Process According to this invention, the production of ethanol from sweet sorghum or sugarcane is carried out by a process comprising steps of:- (a) Size reduction of feedstock The sugars are present within the cellular part of the sweet sorghum or sugarcane. For extracting the sugar, it is necessary to carry out size reduction of the feedstock into appropriate small size. For this purpose, sweet sorghum or sugarcane stalks are unloaded on a feeder table with the help of an electrically Operated cane unloader. The crane is provided with a sling bar attachment. From the feeder table, the stalks of sweet sorghum or sugarcane are discharged on to a cane carrier. A cane kicker is fitted on the carrier, which equals the bed height of feedstock. A fibrizer device is provided which thrashes the sweet sorghum or sugarcane stalks and prepares fine fibers of the input material. The fibrizer prepares the cane to the preparation index of 85 to 95. This fiber form of sugar cane or sweet sorghum stalk enhances the speed of the extraction process. (b) Thermopermeation Thermopermeation process technology is for high efficiency sugar extraction into juice from sweet sorghum/cane. This process is performed in a specially designed moving bed reactor where the fibrized sweet sorghum or sugar cane as obtained in step (a) is soaked in solubilising agent comprising a combination of hot recycled juice from the milling tandem and water. The water may be used individually or in any combination with distillery effluent, evaporation condensate, dewatered juice or fresh water. The water/mixture of water and effluents requirement for extracting fermentable sugar from sweet sorghum or sugarcane is 40% to 50% by weight of feedstock. However, the number of streams (out of four streams) and their exact proportion depends upon the operating conditions of the process such as start-up stage, turned down operation or shut-down-stage, etc. Care is taken to minimize collodal substances in different water streams. The sucrose, glucose, and fructose molecules present in sweet sorghum or sugarcane get solubilised and permeate into the juice. To this mixture, enzymes such as amylase, cellulase, pectinase and pentosanase, protease and B-glucanase are added at a temperature of 65-70°C. This step helps in increasing the yield of fermentable sugars. The use of enzymes helps to extract more sugar in the form of glucose and fructose from the cellulosic, starchy and other carbohydrate polymers part of sweet sorghum or sugarcane. Preferably, any combination of different mentioned above, is used. The total dosage of different enzymes used is between 0.005 to 0.02% by weight of feedstock processed (sweet sorghum or sugarcane) However, the application of a specific enzyme and the dosage level depends upon the mass of sugar cane or sweet sorghum and the composition of the local feed stock. The different streams are returned to a point within the thermopermeation reactor, where the juice solids concentration is about equal to that of incoming water streams. Thermo-permeator is perfectly carried out at a temperature of 40 to 85° C. The temperature selection is based on denaturation of enzyme, extraction of sugar and thermal behaviour of cell wall especially of its component. The pH of the mixture is maintained, by adding suitable acid/alkali, in the range of 5 to 6.5. The fibrized sweet sorghum or sugarcane passes in the counter current thermopermeation reactor with a residence time in the range of 10 to 25 minutes. The exact residence time depends upon the feedstock and can be controlled by speed control device. The treated and soaked sweet sorghum is then continuously fed to a milling tandem comprising 2 to 5 mills in series, to extract sugar-rich juice. The primary juice obtained from the first mill in series is screened for baggacilo particles and then transferred into the thermopermeation reactor tank where the secondary juice coming from the thermopermeation reactor is mixed and the juice is kept for 30-40 minutes in the tank for further conversion of polymer carbohydrates into fermentable sugars. The fiber called bagasse, produced after the final mill is a rich source of fuel energy and may be used as boiler feed for steam generation. Thus, process of thermo-permeation gives 1 to 2% increased sugar extraction as compared to conventional milling operations, and at the same has 20 to 40% reduced energy consumption. Clarification and Concentration of Sugar Rich Juice The mixed juice from themopermeation reactor tank is clarified in settlers by using clarification agents like lime, in the conventional manner. The clarified juice is concentrated by evaporation in falling film, forced circulation, corrugated tube or fluidised bed with multiple effect evaporation system whereas the settled impurities are passed through rotary vacuum filter. The dilute juice coming out from the rotary vacuum filter is recycled back to the clarification system whereas the press-mud generated from the impurities is used for bio-composting. The said concentration by evaporation is carried out to final solid ranging from 18% to 78% w/w depending upon the requirement of intermediate processing or storage of the same for using as raw material for processing to ethanol. The hot condensate water released from the evaporator is reused as a replacement of fresh water in thermopermeation system and also as a source of energy-saving on the overall energy requirement for the process. The concentration of juice above 65% solids helps to store the same for long periods of time without causing any damage to the sugar content due to its low water activity, and can be used as a substrate for a fermentation process to produce ethanol. The concentrated syrup so obtained is used as a raw material for fermentation. (d) Fermentation The syrup as obtained above is introduced into continuous fermentation system. Number of fermenters can vary from 1 to 6, depending upon plant capacity. The final sugar concentration is manufactured between 14-20%. A specially developed flocculating strain of yeast is used for the fermentation. The syrup is continuously fed to the fermentation. The yeast ferments sugar to alcohol. The fermentation is carried out at a temperature of 30-33 degree C over a period of 10-22 hours, depending on the requirement of final alcohol concentration. The fermented mash containing 9 to 11 % v/v alcohol, continuously overflowing from the fermentation process is introduced into a continuous yeast gravity settler. Here, in the absence of agitation or turbulence, the yeast clumps together to form floes. These settle under the influence of gravitational force. This yeast can then be separated and recycled to the fermentation process. The recycling of yeast helps to reduce the fermentation retention time saves the sugars incurred for the yeast growth during the process and speeds up the entire process. Distillation and Dehydration The supernatant de-yeasted mash from the yeast settling plant is continuously fed to the distillation system to separate, concentrate and purify the product, alcohol, which is then fed to the molecular dehydration system to remove the trace water and produce Absolute alcohol or ethanol. The wastewater generated after distillation is called effluent. Effluent generated from distillation system as shown in figure 2 is cooled and heat is reused for pre-heating the fermented medium. This cooled effluent is introduced into the fermentation system (as shown in figure 2) for diluting the syrup to desired sugar concentration, which can be fermented by yeast. The cooled effluent is also recycled to Thermopermeation section (as shown in figure 1) as per requirement. The recycling of effluent reduces considerably the need for treatment of effluent before it is finally disposed off, up to a minimum value of 1.5 to 2 liters instead of the normal / conventional 10 to 14 liters of effluent per liter of alcohol produced. The low quantity of effluent thus produced, also has very low organic load (Biological Oxygen Demand [BOD] / Chemical Oxygen Demand [COD]), making it suitable for further waste treatment. This can be further reduced to 0.5 to 1 liters of effluent per liter of alcohol produced by mean of evaporation. This effluent can be composted with the press mud generated during the process. It is to be understood that the process of the present invention is susceptible to changes, modifications, and adaptation by those skilled in the art. Such variant embodiments incorporating the features and concepts of the present invention are intended to be within the scope of the present invention, which is further set forth under the following claims: - We Claim-: 1. A process for production of ethanol from sweet sorghurr/ sugarcane comprising: ( a ) preparing fine fibers of the stalk of the feedstock; ( b ) extracting sugar from the fibrized feed stalk; ( c) clarifying the juice in a conventional manner; ( d ) concentration of juice to 18 to 78% by evaporation by any of conventional methods; (e) subjecting the concentrated juice to continuous fermentation by yeast at a temperature of 30°C to 33°C, maintaining sugar concentration during fermentation in the range of 14 -20% and segregating the yeast; (f) distillation of the de-yeasted fermented mash; and ( g ) removing the traces of water by molecular dehydration. Characterized in that :- (a) said extraction of sugar from the fibrized feed stock is carried out by:- (i) subjecting the fibrized feed stock to thermopermeation comprising soaking the fibrized feed stock in a solubilising agent at a temperature of 40°C to 85°C in a moving bed reactor, wherein solubilising agent is a mixture of fresh water and juice recycled from sugar extraction mills wherein the solublising agent is taken in quantity 40 to 50% by weight of feed stock and wherein the" resident time for thermopermeation is 10 to 25 minutes; (ii) adjusting pH of the mixture by adding acid /alkali so that pH is between 5 to 6.5; (iii) adding enzyme at a temperature of 65-70°C in the dosage of 0.005 to 0.02% by weight of feedstock; and (iv ) feeding treated feedstock and extracting sugar by 2 to 5 sugar extraction mills. (b) press mud generated from the impurities during said concentration is mixed with effluents obtained from distillation for the purposes of bio-composting; (c) hot condensate water from evaporator is recycled to moving bed reactor for thermopermeation; ( d ) yeast used is Saccharomyces cerevasiae which forms floes by gravity and settles down in a continuous gravity settlerand floes of yeast thus formed are segregated and recycled to fermentation process enabling faster fermentation within 10 to 22 hours; and ( e ) the effluents generated from distillation are reused for reheating the fermentation medium and cooled effluents are" used for diluting the syrup to desired concentration. 2. A process as claimed in claim 1 wherein said thermopermeation is carried at 65° C - 70° C. 3. A process as claimed in claim where in enzyme is selected from amylase, cellulase, pectinase, pentosanase protease, B-gluconase or a combination thereof. 4. A process as claimed in claim 1 wherein for said thermopermeation, the said solubilising agent is a mixture of distillery effluent, evaporation condensate and dewatered juice. 5. A process for production of ethanol from the stalks of sweet sorghum or sugarcane as substantially described and illustrated by the accompanying flow chart. Date: 29tn July, 2004 (V. D GULWANI) Applicant"sAgent Dua Associates

Documents:

820-mum-2004-abstract(17-10-2005).doc

820-mum-2004-abstract(17-10-2005).pdf

820-mum-2004-cancelled pages(17-10-2005).pdf

820-mum-2004-claims(granted)-(17-10-2005).doc

820-mum-2004-claims(granted)-(17-10-2005).pdf

820-mum-2004-correspondence(20-10-2005).pdf

820-mum-2004-correspondence(ipo)-(21-09-2005).pdf

820-mum-2004-drawings(17-10-2005).pdf

820-mum-2004-form 1(02-08-2004).pdf

820-mum-2004-form 19(28-09-2004).pdf

820-mum-2004-form 2(granted)-(17-10-2005).doc

820-mum-2004-form 2(granted)-(17-10-2005).pdf

820-mum-2004-form 26(02-08-2004).pdf

820-mum-2004-form 26(27-07-2004).pdf

820-mum-2004-form 3(02-08-2004).pdf

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