Efficient methods and compositions for recovery of products from organic acid pretreatment of plant materials

Abstract

To provide efficient methods and compositions for recovery of products from organic acid pretreatment of plant materials.SOLUTION: The invention is related to compositions and processes concerning (i) recovery of organic acids from a cellulosic pulp derived from organic acid pretreatment of plant materials, (ii) treatment of cellulose recovered from the cellulosic pulp derived from the organic acid pretreatment of the plant materials prior to conversion to glucose, (iii) separating and cleaning lignin from a lignin suspension derived from the organic acid pretreatment of the plant materials, (iv) recovery of organic acids from an aqueous phase of the organic acid pretreatment of the plant materials, (v) recovery of residual organic acids from hemicellulose-containing fractions derived from the organic acid pretreatment of the plant materials, and (vi) an organic fertilizer produced from cellulose and hemicellulosic juice derived from the organic acid pretreatment of the plant materials.SELECTED DRAWING: None

Description

[Technical field]

[0001] The present invention relates to compositions and processes for (i) recovery of organic acids from cellulose pulp derived from organic acid pretreatment of plant material, (ii) treatment of cellulose recovered from cellulose pulp derived from organic acid pretreatment of plant material prior to conversion to glucose, (iii) separation and purification of lignin from a lignin suspension derived from organic acid pretreatment of plant material, (iv) recovery of organic acids from the aqueous phase of organic acid pretreatment of plant material, (v) recovery of residual organic acids from a hemicellulose-containing fraction derived from organic acid pretreatment of plant material, and (vi) organic fertilizers produced from cellulose and hemicellulose juice derived from organic acid pretreatment of plant material. [Background technology]

[0002] In a first aspect, the present invention relates to a method for recovering organic acids from cellulose pulp by applying a dryer and a desolventizer in combination. This aspect of the invention increases the efficiency of existing organic acid pretreatment processes by allowing the recovery and reuse of the organic acids used to dissolve the hemicellulose and lignin contained in lignocellulosic plant material. After the dissolution step of the organic acid pretreatment of the plant material, a mixture of soluble and insoluble parts is obtained. After separation of the mixture into soluble and insoluble fractions, cellulose pulp and an extract are obtained. The cellulose pulp represents about 62% of the soluble fraction, mainly composed of organic acids and water, and 38% of the insoluble fraction, mainly composed of undissolved cellulose.

[0003] Organic acid pretreatment processes suitable for use in the present invention are described in International Patent Publication Nos. WO2011 / 154293 and WO2010 / 006840, the entire contents of which are incorporated herein by reference. The present invention may also relate to the recovery of organic acids from the organic acid pretreatment step, including partial elimination of lignin to obtain a residual overall lignin level of 0.3% to 4%. Such a step is described in International Patent Publication No. WO2012 / 049054, the entire contents of which are incorporated herein by reference.

[0004] In such processes, not only do the unrecovered organic acids represent a significant portion of the unit's operating costs, but the unrecovered organic acids also impact environmental considerations. Thus, efficient recovery of organic acids from the cellulose pulp produced by organic acid pretreatment of plant material offers both economic and environmental advantages over existing methods.

[0005] In another aspect, the present invention further relates to a process comprising organic acid pretreatment of plant material to treat cellulose by a combination of neutralization and alkalization, the cellulose being derived from an existing process for producing bioethanol or other products, such an existing process being described in U.S. Patent Publication No. 2013 / 0183733, the entire contents of which are incorporated herein.

[0006] The production of bioethanol through a process including a step of organic acid pretreatment comprises a first step of breaking down the lignocellulosic plant material by subjecting it to a mixture of formic acid, acetic acid and water, the next step being the separation of the cellulose from the other materials. A partial elimination of lignin prior to the enzymatic hydrolysis step in order to achieve the highest possible yield of enzymatic hydrolysis of the separated cellulose is disclosed, such treatment of the cellulose to eliminate the lignin and achieve a preferred lignin level with an overall residual lignin level equal to approximately 1.65% is carried out by means of treating the cellulose with sodium hydroxide, followed by a washing step intended to eliminate the residual sodium hydroxide prior to the enzymatic hydrolysis.

[0007] Typically, processing of cellulose derived from organic acid pretreatment of plant material is performed by adding sodium hydroxide directly to the cellulose to adjust the pH to pH 10-pH 12, followed by a separation step to separate the mixture into treated cellulose and a filtrate (containing primarily sodium hydroxide and other soluble fractions). Cellulose produced by existing organic acid pretreatment processes contains residual organic acids from the pretreatment process, ranging from 0.5% to 5% by weight of the dry cellulose. Neutralization of these residual acids consumes large amounts of sodium hydroxide, resulting in direct cost increases for bioethanol production and indirect cost increases for filtrate processing. Thus, a method over existing methods to minimize the amount of sodium hydroxide required to reach an operable pH range before subsequent processing of the cellulose represents a particularly important advantage.

[0008] In another aspect, the present invention relates to a process for separating and cleaning lignin from a lignin suspension derived from organic acid pretreatment of plant material by the use of centrifugation.

[0009] The organic acid pretreatment process uses an organic acid solution as a reagent to dissolve the hemicellulose and lignin contained in the plant material, and after separation, separates the extract from the mixture. The extract, which is mainly composed of cellulose, dissolved hemicellulose, lignin, minerals, organic acids, water, etc., is concentrated by an evaporation system to remove a part of the organic acid and water to a dry matter content of 55%-65% calculated from the total weight of the concentrated extract. Existing processes are described in International Patent Publication Nos. WO2000 / 068494, WO2009 / 092749, WO2011 / 154293, and WO2015 / 185639, the entire contents of each of which are incorporated by reference.

[0010] In such a process, a lignin suspension is typically obtained by dispersing lignin in a mixture of concentrated extract and water, and the separation of lignin and sugars present in the lignin suspension is performed through a filter press. After separation of the lignin, a lignin press cake and a sugar-containing liquid are obtained. The pressed lignin cake is washed with water or a combination of air and water to finally obtain washed lignin and a wash liquid.

[0011] However, due to the structural limitations of the device, the filter press cannot be run continuously throughout the entire process, and therefore a homogenous product cannot be produced by washing the cake using a filter press. Because the filtered lignin cake is rectangular, the washing path across the lignin cake varies and is generally inconsistent. The present disclosure provides a method for recovering lignin by centrifugation, thereby improving the recovery of lignin from lignin suspensions while reducing water usage and therefore energy consumption.

[0012] In another aspect, the invention relates to a process for producing hemicellulose juice from a hemicellulose mixture produced by organic acid pretreatment of plant material, composed mostly of dissolved hemicellulose, organic acid, and water, by a combination of evaporation and stripping. The organic acid pretreatment process uses an organic acid solution as a reagent to dissolve the hemicellulose and lignin contained in the lignocellulosic feedstock at relatively low temperatures and atmospheric pressure, and the process is carried out at relatively low temperatures and atmospheric or vacuum pressure to prevent the creation of furfural, even during the subsequent extraction treatment.

[0013] Typically, the extract, consisting of dissolved hemicellulose, lignin, organic acids, and water, is concentrated by a multiple-effect evaporation system to remove a portion of the organic acids and water to a dry matter content of 55%-65% calculated from the total weight of the concentrate. The lignin contained in the concentrate is separated by an existing process for separating lignin and sugars from the extract, which requires mixing the concentrate with an equal part by weight of water before separating the lignin and sugars, and washing the separated lignin with water to remove the remaining sugars, organic acids, total soluble material, and water, which are collected together to form the hemicellulose mixture of dissolved hemicellulose, organic acids, and water produced in this process. Such a process is described in International Patent Publication Nos. WO2011 / 154293 and WO2010 / 006840, each of which is incorporated in its entirety.

[0014] The dissolved hemicellulose in the hemicellulose mixture mainly contains xylose and arabinose, which can be used to produce ethanol and other industrial products. However, the organic acids present in the hemicellulose mixture will inhibit the conversion of xylose and arabinose to ethanol and other industrial products. Therefore, efficient removal of organic acids from the hemicellulose mixture to produce hemicellulose juice is particularly important to maximize the yield of ethanol from the available sugars in the hemicellulose juice.

[0015] In another aspect, the present invention relates to recovering organic acids from a high-water organic acid solution produced by an organic acid pretreatment process of plant material. Typically, the content of organic acids in such a process is greater than 83% of the total weight of the solution. The organic acids act as reagents to dissolve hemicellulose and lignin contained in the lignocellulosic raw material at relatively low temperatures and atmospheric pressure to avoid the production of furfural during the pretreatment process. After separation, the liquid contains dissolved hemicellulose, lignin, organic acids, water, and other components. The water, which is composed of the organic acid solution and the water in the raw material, is concentrated by an evaporation system to remove a portion of the organic acids along with the water, which forms a first stream of high-water organic acid solution.

[0016] Existing processes for separating lignin and sugars from the extract separate the lignin contained in the concentrate by precipitating the lignin in the concentrate by mixing the concentrate with an equal part by weight of water before separating the lignin from the concentrate, after which the separated lignin is washed with water to remove residual sugars, organic acids, and other water-soluble components.

[0017] All soluble materials, including water, the water remaining in the concentrate, the water mixed with the concentrate to precipitate the lignin, and the water used as wash water are collected together to form a mixture consisting primarily of dissolved hemicellulose, organic acids, water (remaining in the process and added), and other minor components. Such a process is described in International Patent Applications WO2011 / 154293 and WO2010 / 006840, the entire contents of each of which are incorporated herein by reference.

[0018] A combined evaporation and stripping process is disclosed for efficiently removing organic acids from high water content organic acid solutions, regardless of their source. The disclosed process includes a first pass multiple effect evaporator to partially evaporate the organic acids from the mixture along with the water, and the evaporator condensate, which contains primarily organic acids and water, forms a second stream of high water content organic acid solution.

[0019] The concentrated organic acid mixture from the evaporator is fed to a stripping column where the organic acids are further removed to a content of less than 2%, and the condensate from the stripping column forms a third stream of high water content organic acid solution.

[0020] The fourth stream of high-water organic acids originates from the recovery of organic acids from the dried cellulose pulp by using a desolventizer adapted to utilize steam to remove residual organic acids from the dried cellulose pulp and contains about 62% soluble portion (consisting primarily of organic acids and water) and about 38% insoluble portion (consisting primarily of cellulose). In this embodiment of the invention, the condensate from the desolventizer forms the fourth stream of high-water organic acids solution.

[0021] In order to recycle the organic acids and water to the organic acid pretreatment process, additional water must be removed from these four high water content organic acid solution streams to meet the moisture content requirements of the extraction and delignification steps.

[0022] In another aspect, the present invention relates to a method for producing organic fertilizer by utilizing stillage from cellulosic and hemicellulose juices.

[0023] The present invention is based on organic acid pretreated plant material, in particular cereal straw, serving as the raw material. The separation of lignocellulosic raw material into cellulose, hemicellulose juice, and lignin by organic acid pretreatment process, hydrolysis and fermentation of cellulose and hemicellulose juice, and conversion of most of the cellulose and hemicellulose juice to ethanol are described in International Patent Application No. WO2015 / 185639, the entire contents of which are incorporated herein.

[0024] Typically, in processes for producing fuel ethanol after fermentation, a mixture of fermented cellulose and hemicellulose juice is fed to a mash column of a distillation system where ethanol is extracted to produce fuel ethanol. In such processes, the residue is discharged from the bottom of the mash column. One result of the organic acid pretreatment process is that most of the nutritional components of the lignocellulosic feedstock (protein, potassium, phosphate, etc.) are separated into the hemicellulose juice and mixed with the fermentation materials (yeast, glycerol, etc.) as the distillation effluent. The use of this distillation effluent becomes a significant problem, as the distillation effluent is treated as waste without being used productively, and the treatment of such waste is expensive. In existing processes, no good method has been proposed. This aspect of the invention provides a process for producing a thermodynamically efficient method of decanting and evaporating the distillation effluent solids to form a valuable organic fertilizer base while simultaneously providing steam from the distillation effluent as a thermocouple to a distillation effluent solids evaporation system, thereby recovering and treating the non-productive distillation effluent. [Prior art documents] [Patent documents]

[0025] [Patent Document 1] International Publication No. 2011 / 154293 [Patent Document 2] International Publication No. 2010 / 006840 [Patent Document 3] International Publication No. 2012 / 049054 [Patent Document 4] US Patent Publication No. 2013 / 0183733 [Patent Document 5] International Publication No. 2000 / 068494 [Patent Document 6] International Publication No. 2009 / 092749 [Patent Document 7] International Publication No. 2015 / 185639 Summary of the Invention [Means for solving the problem]

[0026] A first aspect of the present invention discloses a method and composition for efficient, complete and economical recovery of organic acids from cellulose pulp by a combination of a dryer and a desolventizer. The method includes a first step of using a dryer to reduce the organic acids to a content of 5% to 12% calculated from the total weight of the dried cellulose pulp. At this level, it is difficult to further remove the organic acids by continuing the drying. To overcome this difficulty, the present invention includes a second step of using a desolventizer to further remove the organic acids using direct steam as the desolventization medium to reduce the organic acid content to less than 2% compared to the total weight of the desolventized cellulose pulp.

[0027] Another aspect of the invention is to provide processes and compositions for treating cellulose by a combination of neutralization and alkalization that prepares cellulose for enzymatic digestion using the minimum amount of sodium hydroxide possible, as well as a means of recycling sodium hydroxide liquor from the alkalization step to the neutralization step, reducing the cost of bioethanol production and associated waste disposal using minimal sodium hydroxide.

[0028] Another aspect of the invention provides a lignin separation and cleaning process and composition using centrifugation, further including recycling a certain portion of the centrate and online washing, to obtain pure lignin, reduce overall water consumption, and obtain high quality lignin.

[0029] Another aspect of the invention is a process for efficiently and economically removing organic acids from a hemicellulose mixture of dissolved hemicellulose, organic acids, and water by combining evaporation and stripping to produce a hemicellulose juice composition. The process comprises a multiple effect evaporation system for partially evaporating the organic acids together with water in a first step to a dry matter content of 40% to 70% calculated from the total weight of the concentrated hemicellulose juice. The process further comprises a second step in which the concentrated hemicellulose juice is fed to a stripping column where the organic acids are further removed to a content of less than 2% calculated from the total weight of the hemicellulose juice.

[0030] Another aspect of the present invention is a process for efficient and economical removal of water from a high-water content organic acid solution by a process including multi-column distillation to produce a composition suitable for subsequent recycling in an organic acid pretreatment process, characterized in that a) employing a 2-5 column distillation system to recover organic acids, b) feeding unused steam only to the first column of the multi-column distillation system, c) providing the steam discharged from the previous column as heat energy to the subsequent columns in sequence, d) feeding one or more streams of high-water content organic acid solution to different columns in the multi-column system to balance the energy requirements of the columns comprising the distillation system, e) adjusting the content of organic acids in the condensate of the first column to minimize unused steam consumption, and f) recycling the total organic acids and total water discharged from the multi-column distillation system to the overall process constituting the organic acid pretreatment of plant material, which can maximally reduce the energy, i.e., steam consumption, for recovering organic acids, while recycling the total organic acids and water to the pretreatment process.

[0031] Another aspect of the invention is a method for efficiently and economically producing an organic fertilizer composition using fermentation of distillery effluent of cellulose and hemicellulose juices. Distillery effluent is rich in organic matter and nutrients and meets the requirements for organic fertilizer. Organic fertilizers can improve soil quality as well as provide nutrients to plants, such as crops. In contrast, chemical fertilizers provide nutrients to plants but can damage the soil. Organic fertilizers are an important emerging direction for agriculture. This aspect of the invention features the use of distillery effluent (fermentation by-product) to produce valuable organic fertilizers by an efficient and economical method. The method includes separating the distillery effluent by decantation to obtain a solid fraction of the distillery effluent and a thin distillery effluent that includes a more dilute fraction of the distillery effluent. The method further includes concentrating the thin distillation effluent by a multiple-effect evaporation system to obtain a concentrated distillation effluent, mixing the solid fraction and the concentrated distillation effluent to obtain a mixture, drying the mixture by a dryer to obtain an organic fertilizer, and supplying the steam discharged from the dryer as heat energy for the multiple-effect evaporation system and the unused steam as supplemental heat energy to the multiple-effect evaporation system. The present invention provides, for example, the following: (Item 1) 1. A desolventized cellulose pulp containing less than 2% organic acids, a) drying the cellulose pulp produced by pre-treatment of the plant material with an organic acid in a dryer to remove the organic acid to a content of 3% to 18% calculated from the total weight of the dried cellulose pulp; b) capturing steam emitted from the dryer as a heat energy source for use in the extract concentration system and other organic acid pretreatment operation systems; c) condensing the vapor captured in the extract concentration system to form a first phase of the organic acid solution of the organic acid pretreatment process, or optionally using the vapor to provide heat energy for further operational steps within the organic acid pretreatment process; d) further removing the organic acids from the cellulose pulp using direct steam in a desolventizer; and e) condensing the organic acid in the vapor discharged from the desolventizer to obtain a second phase of organic acid solution of the organic acid pretreatment process. (Item 2) 2. The desolventized cellulose pulp of item 1, wherein the organic acid of the process comprises a mixture of formic acid, acetic acid, and water. (Item 3) 2. The desolventized cellulose pulp of item 1, wherein the organic acid of the process comprises a mixture of formic acid, acetic acid, furfural, and water. (Item 4) 2. The desolventized cellulose pulp of item 1, wherein the organic acid of the process comprises a mixture of formic acid, furfural, and water. (Item 5) 2. The desolventized cellulose pulp of item 1, wherein the organic acid of the process comprises a mixture of formic acid and water. (Item 6) 2. The desolventized cellulose pulp of claim 1, wherein the dryer of the process is a bulk dryer. (Item 7) 7. The bulk dryer according to item 6, selected from the group consisting of a tube dryer, an air pressure dryer, and a rotary disk dryer. (Item 8) 8. The bulk dryer according to item 7, wherein the bulk dryer is a tube dryer. (Item 9) 2. The desolventized cellulose pulp according to item 1, wherein the dryer of the process is operated at a temperature between 80°C and 160°C. (Item 10) 2. The desolventized cellulose pulp according to item 1, wherein the first phase of the organic acid solution of the organic acid pretreatment process comprises an organic acid content of 50% to 95% of the total weight compared to the first phase of the organic acid solution recovered in step c) of the process. (Item 11) 2. The desolventized cellulose pulp according to item 1, wherein the first phase of organic acid solution recovered in process step c) is reused in the organic acid pretreatment process. (Item 12) 2. The desolventized cellulose pulp according to item 1, wherein the desolventizer uses direct steam at a temperature between 90°C and 130°C. (Item 13) 2. The desolventized cellulose pulp according to item 1, wherein the second phase of organic acid solution of the organic acid pretreatment process comprises an organic acid content of 5% to 60% of the total weight compared to the second phase of organic acid solution in step e) of the process. (Item 14) 2. The desolventized cellulose pulp according to item 1, wherein the second condensation system for recovering the organic acids in process step e) comprises 1 to 3 condensers. (Item 15) 2. The desolventized cellulose pulp according to claim 1, wherein the second condensation system for recovering the organic acids in process step e) comprises two condensers. (Item 16) 1. An alkalized cellulose prepared by a process comprising: a) neutralizing the organic acids contained in the cellulose produced from organic acid pretreatment of plant material with sodium hydroxide liquor recycled from step d) of the process to form a neutralized cellulose mixture; b) separating the neutralized cellulose from the neutralized cellulose mixture using a press and discharging the filtrate directly into a wastewater treatment system; c) alkalizing the neutralized cellulose in a reactor by adding sodium hydroxide solution to form an alkalized cellulose mixture; and d) separating the alkalized cellulose from the alkalized cellulose mixture using a press, wherein the sodium hydroxide liquid (filtrate of the alkalized cellulose mixture) comprises sodium hydroxide for reuse in step a) of the process. (Item 17) 17. The alkalized cellulose prepared by the process according to item 16, wherein the organic acid in step a) of the process comprises only formic acid. (Item 18) 17. The alkalized cellulose prepared by the process according to item 16, wherein the organic acid in step a) of the process comprises a mixture of acetic acid and formic acid. (Item 19) 17. Alkalized cellulose prepared by the process according to item 16, wherein neutralization of the organic acids contained in the cellulose produced from organic acid pretreatment of plant material is achieved by adding the sodium hydroxide liquor recycled from step d) of the process, or by adding sodium hydroxide comprising a combination of recycled sodium hydroxide liquor from step d) of the process and unused sodium hydroxide. (Item 20) Item 17. The alkalized cellulose prepared by the process according to item 16, wherein the neutralized cellulose mixture has a pH of pH 5 to pH 8. (Item 21) Item 17. The alkalized cellulose prepared by the process according to item 16, wherein the neutralized cellulose has a dry solids content of 30% to 45%, calculated from the total weight of the neutralized cellulose. (Item 22) 17. The alkalized cellulose prepared by the process according to item 16, wherein the alkalized cellulose has a pH of pH 10 to pH 12. (Item 23) Item 17. The alkalized cellulose prepared by the process according to item 16, wherein the alkalized cellulose has a dry solids content of 30% to 45%, calculated from the total weight of the alkalized cellulose. (Item 24) 17. The alkalized cellulose prepared by the process according to item 16, wherein the sodium hydroxide solution of step d) of the process has a pH of pH 10 to pH 12. (Item 25) 17. Alkalized cellulose prepared by the process according to item 16, wherein the process is carried out at a temperature of 50°C to 100°C. (Item 26) 17. The alkalized cellulose prepared by the process of claim 16, wherein the press is a mechanical press. (Item 27) 27. The mechanical press according to item 26, comprising a screw press. (Item 28) 1. A lignin composition comprising: a) separating lignin from a lignin suspension produced from an organic acid pretreatment of plant material by centrifugation; b) cleaning the lignin in the centrifuge by applying a wash fluid to the lignin multiple times during centrifugation to form a plurality of centrates; c) collecting the first centrate and the second centrate for use in hemicellulose juice concentration; d) recycling the third centrifugate to separate the lignin in the concentrated extract in the separation step of the process; e) discharging the lignin from the centrifuge. (Item 29) 30. The lignin composition prepared by the process of claim 28, wherein the centrifuge is a scraper centrifuge. (Item 30) 30. The lignin composition prepared by the process of claim 28, wherein the centrifuge is equipped with a spray device for delivering washing liquid. (Item 31) 30. The lignin composition prepared by the process of claim 28, wherein the centrifuge rotates continuously throughout the process. (Item 32) 30. A lignin composition prepared by the process of claim 28, wherein the wash solution comprises formic acid, acetic acid, and water. (Item 33) 30. A lignin composition prepared by the process of claim 28, wherein the wash liquid consists solely of water. (Item 34) 30. The lignin composition prepared by the process of claim 28, wherein the multiple applications of wash liquor include a first application of a wash liquor comprised of high organic acid content wash water, a second application of a wash liquor comprised of low organic acid content wash water, and a final application of a wash liquor comprised of virgin water. (Item 35) Item 33. The cleaning solution according to item 32, wherein the formic acid content is 0% by weight to 30% by weight. (Item 36) Item 33. The cleaning solution according to item 32, wherein the acetic acid content is 0% by weight to 20% by weight. (Item 37) 30. The lignin composition prepared by the process of claim 28, wherein the first centrate is comprised of the liquid separated from the lignin suspension applied to the centrifuge. (Item 38) 30. A lignin composition prepared by the process of claim 28, wherein the second centrate is comprised of the first wash solution applied to the lignin in the centrifuge. (Item 39) 30. The lignin composition prepared by the process of claim 28, wherein the first and second centrifuges are collected and used for hemicellulose juice production. (Item 40) 30. A lignin composition prepared by the process of claim 28, wherein the third centrate is comprised of the second and any subsequent washes applied to the lignin in the centrifuge. (Item 41) 30. The lignin composition prepared by the process of claim 28, wherein the third centrifugate is recycled to the lignin precipitation step. (Item 42) 29. The lignin composition prepared by the process of claim 28, wherein the first centrate comprises 10% to 60% of the total centrate. (Item 43) 29. The lignin composition prepared by the process of claim 28, wherein the second centrifugal fraction comprises 10% to 30% of the total centrifugal fraction. (Item 44) 29. The lignin composition prepared by the process of claim 28, wherein the third centrifugal fraction comprises 10% to 50% of the total centrifugal fraction. (Item 45) 30. A lignin composition prepared by the process of claim 28, wherein the lignin is 90% to 99% pure, based on the total weight of the cleaned lignin. (Item 46) 1. A hemicellulose juice composition comprising: a) introducing a hemicellulose mixture, which is composed of dissolved hemicellulose, organic acids, and water, and other components, produced by organic acid pretreatment of a plant material, into a multiple effect evaporation system; b) evaporating the hemicellulose mixture in the multiple effect evaporator to form a concentrated hemicellulose juice having a dry matter content of 40% to 70% by weight; and c) removing organic acids from the concentrated hemicellulose juice in a stripping column to form a hemicellulose juice, wherein the hemicellulose juice contains less than 2% by weight of organic acids. (Item 47) 47. The hemicellulose juice composition prepared by the process of claim 46, wherein the organic acid comprises formic acid. (Item 48) 47. The hemicellulose juice composition prepared by the process of claim 46, wherein the organic acids include formic acid and acetic acid. (Item 49) Item 47. The hemicellulose juice composition prepared by the process according to item 46, wherein the content of the dissolved hemicellulose in the hemicellulose mixture is 2% by weight to 20% by weight. (Item 50) Item 47. The hemicellulose juice composition prepared by the process according to item 46, wherein the organic acid content of the hemicellulose mixture is 10% by weight to 30% by weight. (Item 51) 47. The hemicellulose juice composition prepared by the process of claim 46, wherein the multiple effect evaporation system is a double effect evaporation system. (Item 52) 47. The hemicellulose juice composition prepared by the process of claim 46, wherein the multiple effect evaporation system is a triple effect evaporation system. (Item 53) 47. The hemicellulose juice composition prepared by the process of claim 46, wherein the multiple effect evaporation system is a quadruple effect evaporation system. (Item 54) 47. The hemicellulose juice composition prepared by the process of claim 46, wherein the multiple effect evaporation is operated with the first effect evaporator at a temperature between 60°C and 160°C. (Item 55) 47. The hemicellulose juice composition prepared by the process of claim 46, wherein the multiple effect evaporation system is operated with the last effect evaporator at a temperature between 25°C and 60°C. (Item 56) 47. The hemicellulose juice composition prepared by the process of claim 46, wherein the multiple effect evaporation system utilizes the steam discharged from the top of the previous evaporator as heat energy for the next evaporator. (Item 57) 47. The hemicellulose juice composition prepared by the process of claim 46, wherein the hemicellulose mixture is fed to the last evaporator and sequentially discharged from the first evaporator. (Item 58) 47. The hemicellulose juice composition prepared by the process of claim 46, wherein the stripping column utilizes direct steam as a stripping agent. (Item 59) 47. The hemicellulose juice composition prepared by the process of claim 46, wherein the stripping column is operated at 60°C to 160°C. (Item 60) 47. The hemicellulose juice composition prepared by the process of claim 46, wherein the steam discharged from the stripping column is used as heat energy for the first evaporator of the multiple effect evaporation system. (Item 61) 47. A hemicellulose juice composition prepared by the process of claim 46, wherein the hemicellulose juice does not contain furfural. (Item 62) 1. A method for recovering organic acids from a highly aqueous organic acid solution by multi-column distillation, comprising: a) recovering the organic acid by using a 2-5 column distillation system; b) directly supplying vapor to only the first column of the multi-column distillation system; c) sequentially providing steam to a subsequent column from the steam discharged from a previous column; c) feeding one or more high water organic acid solution streams to different columns in the multi-column system to balance the energy requirements of the column comprising the distillation system; d) adjusting the content of the organic acid in the condensate of the first column to minimize unused steam consumption; e) recycling the total organic acids and total water discharged from the multi-column distillation system. (Item 63) Item 64. The process of item 62, wherein the high water content organic acid solution comprises formic acid, acetic acid, and water. Item 63. The process of item 62, wherein the high water content organic acid solution comprises formic acid and water. (Item 65) Item 63. The process of item 62, wherein the high water content organic acid solution comprises formic acid and acetic acid. (Item 66) Item 63. The process of item 62, wherein the high water content organic acid solution comprises formic acid. (Item 67) Item 63. The process of item 62, wherein the high water content organic acid solution comprises acetic acid. (Item 68) Item 63. The process according to item 62, wherein the multi-column distillation is carried out using a distillation system comprising 2 to 5 columns. (Item 69) Item 63. The process of item 62, wherein the multi-column distillation is carried out using a distillation system comprising four columns. (Item 70) Item 63. The process of item 62, wherein the most aqueous organic solution stream is directed to the last column of the distillation system. (Item 71) Item 63. The process of item 62, wherein the least water organic acid solution stream is directed to the first column of the distillation system. (Item 72) Item 63. The process of item 62, wherein the organic acid and water has an organic acid content of 0.5% to 10% by weight in the condensate discharged from the top of the first column. (Item 73) Item 63. The process according to item 62, wherein the organic acid and water have a water content of 5% to 15% by weight in the bottom discharge of the first column. (Item 74) Item 63. The process of item 62, wherein the organic acid and water has an organic acid content of 0.2% to 1% by weight in the condensate discharged from the top of the subsequent column. (Item 75) Item 63. The process of item 62, wherein the total condensate is recycled to the organic acid pretreatment process. (Item 76) Item 63. The process of item 62, wherein the multi-column distillation uses a temperature of 120° C. to 175° C. in the first column. (Item 77) Item 63. The process of item 62, wherein the multi-column distillation uses a temperature of 50° C. to 95° C. in the last column. (Item 78) Item 63. The process of item 62, wherein unused steam is supplied only to the first column of the multi-column distillation system. (Item 79) Item 63. The process of item 62, wherein the subsequent column sequentially utilizes the steam discharged from the previous column as thermal energy. (Item 80) An organic fertilizer composition prepared by a process comprising: a) separating stillage from cellulose and hemicellulose juices produced by organic acid pretreatment of plant material using a decanter to obtain a stillage solid fraction and a thin stillage; b) concentrating said lean stillage using a multiple effect evaporation system to obtain a concentrated stillage, said steam for said multiple effect evaporation system being supplied from steam discharged from said dryer in step d) of said process, optionally supplemented with unused steam; c) mixing the solid fraction with concentrated distillation effluent to obtain a mixture; and d) drying the mixture to obtain the organic fertilizer, wherein the steam discharged from the dryer is supplied to the multiple effect evaporation system of the process as heat energy for the multiple effect evaporation system to obtain the organic fertilizer. (Item 81) 81. The organic fertilizer composition prepared by the process according to item 80, wherein the solid fraction comprises a dry solids content of 20% to 45% by weight. (Item 82) 81. The organic fertilizer composition prepared by the process according to item 80, wherein the thin stillage is concentrated in an evaporator equipped with a four-effect evaporation system. (Item 83) 81. The organic fertilizer composition prepared by the process according to item 80, wherein the thin stillage is concentrated in an evaporator equipped with a five-effect evaporation system. (Item 84) 81. The organic fertilizer composition prepared by the process according to item 80, wherein the thin stillage is concentrated in an evaporator equipped with a six-effect evaporation system. (Item 85) 81. The organic fertilizer composition prepared by the process according to item 80, wherein the thin stillage is concentrated by multiple-effect evaporation carried out at a temperature between 30°C and 150°C. (Item 86) 81. The organic fertilizer composition prepared by the process according to item 80, wherein the concentrated distillation distillation effluent produced by multiple effect evaporation has a dry matter content of 28% to 45% by weight. (Item 87) 81. The organic fertilizer composition prepared by the process according to item 80, wherein the mixing of the solid fraction and the concentrated stillage is carried out in a mixer. (Item 88) 81. The organic fertilizer composition prepared by the process according to item 80, wherein the drying of the mixture is carried out by a dryer selected from the group of tube dryers, pneumatic dryers, or similar dryers. (Item 89) 81. An organic fertilizer composition prepared by the process according to item 80, wherein the mixture is dried to a dry solids content of 50% to 80% by weight. (Item 90) 81. The organic fertilizer composition prepared by the process according to item 80, wherein the mixture is dried at a temperature between 80°C and 160°C. (Item 91) 81. An organic fertilizer composition prepared by the process according to item 80, wherein the organic fertilizer comprises an organic matter content of 30% to 65%. (Item 92) 81. The organic fertilizer composition prepared by the process according to item 80, wherein the organic fertilizer comprises a total nutrient content of 5% to 30% by weight. (Item 93) 81. The organic fertilizer composition prepared by the process according to item 80, wherein the organic fertilizer comprises a moisture content of 20% to 50% by weight. (Item 94) 81. The organic fertilizer composition prepared by the process according to item 80, wherein the organic fertilizer has a pH of from pH 5.5 to pH 8.5. (Item 95) 81. The organic fertilizer composition prepared by the process according to item 80, wherein the stillage is obtained, separately or collectively, from cellulose and hemicellulose juices produced by hydrolysis and fermentation of cellulose and hemicellulose juices. [Brief description of the drawings]

[0032] [Figure 1] FIG. 1 is a process diagram showing how organic acids are recovered from cellulose pulp by a combination dryer and desolventization unit. Cellulose pulp (21) is introduced into a dryer unit (101) to obtain dried cellulose pulp (22) and steam (23). The steam (23) is used to provide heat energy to the extract concentration system as well as other operational units in the overall system. The dried cellulose pulp (22) is fed to a desolventizer (103) to further remove organic acids by utilizing direct steam (23) as a desolventization medium to obtain desolventized cellulose pulp (24). Steam (25) from the desolventization unit is fed to a condenser I (104). Uncondensed steam (26) from condenser I (104) is fed to a condenser II (105). The condensed steam solution (27) from condenser I and the condensed steam solution (28) from condenser II (105) can be combined to form an organic acid solution (13). [Diagram 2]The structure of the desolventizer (103) is shown diagrammatically. Through the feed inlet (106), the dried cellulose pulp (22) is fed to the top of the desolventizer (103). The direct steam (23) erupts from the holes in the plate (109) and then exits through the layer of dried cellulose pulp, during which the direct steam forms organic acid vapor with the residual organic acids contained in the dried cellulose pulp, which is discharged from the vapor outlet (107) of the desolventizer (103). The discharged organic acid vapor is fed to the condenser I (104), and the uncondensed vapor in the condenser I (104) is fed to the condenser II (105). The condensates of the condenser I (104) and the condenser II (105) form the organic acid solution (13). After desolventization, the desolventized cellulose pulp (24) is discharged by the rotary discharger (108). [Diagram 3] Schematic showing the treatment of cellulose by combined neutralization and alkalization, in which cellulose (21) is fed to a neutralization tank (101) where sodium hydroxide (23) and recycled sodium hydroxide liquor (22) are added to form a neutralized cellulose mixture (24). The neutralized cellulose mixture (24) is fed to a press I (102) to obtain a filtrate (25) and neutralized cellulose (26). The filtrate (25) is discharged to a wastewater treatment system (103), while the neutralized cellulose (26) is fed to an alkalization reactor (104). Sodium hydroxide (27) is added in the alkalization reactor (104) to obtain an alkalized cellulose mixture (28). The alkalized cellulose mixture (28) is fed to a press II (105) to obtain sodium hydroxide liquor (22) that is recycled to the neutralization tank and the final alkalized cellulose (29) product. [Figure 4]FIG. 1 is a process diagram showing a process for producing pure lignin. In this process, the third centrate (21) is mixed with the concentrated extract (22) to form a mixture, and by using a continuous or batch emulsifier (101), the mixture is emulsified in a suspension tank (102) to form a stable lignin suspension (23). The lignin suspension (23) is then fed to a centrifuge (103) to separate the lignin suspension into a lignin layer and a first centrate (25). The first centrate (25) is delivered to a multi-effect evaporation system (104) for hemicellulose juice production. A first wash water (27) is introduced to wash the lignin layer to produce a second centrate (26). The first wash water can be high acid content water from the condenser I of the acid distillation unit (5) of FIG. 10-13. The second centrate (26) is also delivered to a multiple effect evaporation system (104) for hemicellulose juice production. A second wash water (28) is introduced into the lignin bed to produce at least a third centrate (21). The second wash water may consist of low acid content wash water from other condensers than condenser I of the acid distillation unit (7) of Figures 10-13, or unused water (29), or a mixture of both. The third and any subsequent centrates may be combined and reintroduced into the suspension tank (102) for suspending the lignin. The washed lignin is discharged from the centrifuge as pure lignin (24). [Diagram 5] The sequence of steps involved in the production of hemicellulose juice is shown. Raw hemicellulose juice (21), separated from the extract by lignin precipitation, filtration, and washing, is fed to a multi-effect evaporation system (101). Concentrated hemicellulose juice (22) and condensed organic acids (23) are produced by the multi-effect evaporator system. Unused steam (26) and concentrated hemicellulose juice (22) are introduced into a stripping column (102) for further removal of organic acids to obtain a stripped hemicellulose juice (24) having an organic acid content of less than 2% of the total weight of the stripped hemicellulose juice, and freshly condensed acids (25). [Figure 6]FIG. 1 is a detailed diagram of a double-effect evaporation and stripping system. The internal label is described in Example 4. [Figure 7] FIG. 1 is a detailed diagram of a triple-effect evaporation and stripping system. The internal label is described in Example 4. [Figure 8] FIG. 1 is a detailed diagram of a four-effect evaporation and stripping system. The internal labels are as described in Example 4. [Figure 9]FIG. 1 is a flow diagram of a process for recovering organic acids from a high-water content organic acid solution by multi-column distillation. Lignocellulosic plant raw material (11) is fed to an extraction step (101). Organic acids (12) are added to the plant material in the extraction step (101) to dissolve hemicellulose and lignin from the plant raw material (11) to obtain an extraction mixture (13). An extraction liquid (14) is produced by separating soluble and suspended particles from the extraction mixture (102), and the insoluble and unsuspended residue comprises cellulose pulp (15). The cellulose pulp (15) is dried in a dryer (109) to produce a dried cellulose pulp (27), and the condensate from the dryer comprising the organic acids can be recycled to the extraction step (101). In this process, the extraction liquid (14) is fed to an evaporation system (103) to partially remove the residual organic acids and water to form a first stream of high-water content organic acid solution (1) and to obtain a concentrate (16). The concentrate (16) is fed to a lignin separation (104) step, in which the lignin is precipitated and separated from the concentrate (16) by the addition of water (17), resulting in a separated lignin (18) and a soluble material (19) containing water. The lignin needs to be washed with various wash waters (20) in a series of lignin washing steps (22) to remove residual sugars, organic acids, and other water-soluble components. The water from the lignin washing step (105) and the soluble material (19) containing the wash waters are pooled to form a mixture (23) of hemicellulose, organic acids, water, and other water-soluble components. To remove the organic acids and reduce the water content from this mixture (23), the mixture (23) is subjected to a multi-effect evaporation (106). The condensate of the multi-effect evaporator forms a second stream of high-water organic acid solution (2). Following the multiple effect evaporation (106), the concentrated mixture (24) is fed to a stripping column (107) where the organic acids are further removed to a content of less than 2%, with the condensate from the stripping column forming a high water content organic acid solution (3) and a third stream of hemicellulose juice (25). To remove the organic acids from the dried cellulose pulp (15), a desolventizer (108) is adapted to remove the residual organic acids using direct steam (26).Condensate from the desolventizer forms a high water content organic acid solution (4) and a fourth stream of desolventized cellulose pulp (28). The four streams of high water content organic acid solution are fed to a multi-column distillation system (110) to reduce the water content. An aqueous acid solution (5) having an acid content of 0.5% to 10% in the condensate discharge is obtained from the top of the first column. Subsequent columns produce a condensate (7) discharge having an acid content of 0.2% to 1%. An aqueous acid solution (6) having an acid content of 5% to 15% comprises the bottom discharge of the first column. All acid percentages are calculated by weight. [Figure 10] Details of a two-column distillation system are shown. Internal labeling is as described in Example 5. [Figure 11] Details of a three-column distillation system are shown. Internal labeling is as described in Example 5. [Figure 12] Details of the four-column distillation system are shown. Internal labeling is as described in Example 5. [Figure 13] Details of the five-column distillation system are shown. Internal labeling is as described in Example 5. [Figure 14] FIG. 1 is a process diagram showing the production of organic fertilizer from the fermentation stillage (21) from the bottom of the mash column (100) of an ethanol distillation system. The stillage (21) is fed to a decanter (101) to obtain a solid fraction (22) and a dilute stillage (23). The dilute stillage (23) is fed to a multiple-effect evaporation system (102) to produce a concentrated stillage (24). The solid fraction (22) and the concentrated stillage (24) are fed to a mixer (103) where the two fractions are mixed to obtain a mixture (25). The mixture (25) is fed to a dryer (104) to obtain a dry mixture (26), which represents a high-quality organic fertilizer. Steam (27) discharged from the dryer (104) can be fed to the multiple-effect evaporator (102) to provide heat energy for the evaporation process, and unused steam (28) is fed to the multiple-effect evaporation system (102) as supplemental heat energy. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0033] Recovery of organic acids from cellulose pulp. A first aspect of the present invention discloses a method and composition for the efficient, complete and economical recovery of organic acids from cellulose pulp by a combined dryer and desolventizer. The organic acids and desolventized cellulose pulp are a) drying the cellulose pulp produced from the organic acid pretreatment of the plant material in a dryer to remove organic acids to a content of 3% to 18% calculated from the total weight of the dried cellulose pulp; b) capturing the steam emitted from the dryer as a heat energy source for use in the extract concentration system and other organic acid pretreatment operation systems; c) condensing the vapor in the extract concentration system and other organic acid pretreatment operation systems to form a first phase of the organic acid solution of the organic acid pretreatment process; d) further removing organic acids from the cellulose pulp to a content of less than 2% using direct steam in a desolventizer; and e) condensing the organic acid vapors released from the desolvator to obtain a second phase of organic acid solution of the organic acid pretreatment process.

[0034] This aspect of the invention relates to a method for recovering organic acids from cellulosic pulp resulting from an organic acid pretreatment process of plant material using a combination dryer and desolventizer, the organic acid pretreatment process using organic acids as reagents to dissolve hemicellulose and lignin contained in lignocellulosic plant material, the residue including the insoluble portion after separation of the cellulosic pulp from the mixture of soluble and insoluble portions is the cellulosic pulp.

[0035] Existing organic acid pretreatment processes may include a step of partially eliminating lignin to obtain a residue with an overall lignin level of 0.3-4% by dry weight of the total cellulose pulp. The content of organic acids in the cellulose pulp may be 35%-65% calculated from the total weight of the cellulose pulp. The content of cellulose in the cellulose pulp may be 30%-50% calculated from the total weight of the cellulose pulp.

[0036] As shown in Figure 1, the cellulose pulp from the organic acid pretreatment process is fed to a dryer. The dryer reduces the organic acids to a content of 3% to 18% calculated from the total weight of the dried cellulose pulp; when the organic acid content is below 3%, the dryer cannot efficiently further remove the organic acids; when the organic acid content is above 18%, the direct steam consumption by the desolvator is inefficient.

[0037] Drying of the cellulose pulp can be carried out by many forms of dryers, which may include tube dryers, pneumatic dryers, spray dryers, rotary disk dryers, and other dryer technologies known to those skilled in the art, with the use of tube dryers being particularly preferred. The dryer step may be carried out at a temperature between 90° C. and 150° C. After drying, the dried cellulose pulp discharged from the dryer is fed to a desolventizer.

[0038] The steam discharged from the dryer can be used for the extract concentration system and can provide heat energy to other systems as well. The condensate of the steam from the dryer condensed in the extract concentration system and other systems forms the first phase of the organic acid solution and can be reused in the organic acid pretreatment process.

[0039] In the desolventizer shown in FIG. 2, the organic acids are further removed from the dried cellulose pulp to a content of less than 2% calculated from the total weight of the desolventized cellulose pulp. The desolventizer can utilize direct steam as a desolventization medium to further remove the organic acids from the dried cellulose pulp. The desolventizer can further remove the organic acids by using direct steam as a desolventization medium in step d) which is carried out at a temperature between 90° C. and 150° C.

[0040] The desolventized cellulose pulp after the desolventization step can be used to produce ethanol and other products.

[0041] The organic acid vapor also contains water released from the desolvator and is recovered by the condensation system of the organic acid distillation system, and the organic acid is recovered for use in the organic acid pretreatment process. The condensation system is implemented by one to three condensers, preferably two condensers.

[0042] Preparation of alkalized cellulose This aspect of the invention is a process for treating cellulose by a combination of neutralization and alkalization to produce alkalized cellulose, comprising the steps of: a) neutralizing the organic acids contained in the cellulose produced from the organic acid pretreatment of the plant material with sodium hydroxide liquor recycled from step d) of the process to form a neutralized cellulose mixture; b) separating the neutralized cellulose from the neutralized cellulose mixture using a press and discharging the filtrate directly into a wastewater treatment system; c) alkalizing the neutralized cellulose in a reactor by adding sodium hydroxide solution to form an alkalized cellulose mixture; and d) separating the alkalized cellulose from the alkalized cellulose mixture using a press, wherein the sodium hydroxide liquid (filtrate of the alkalized cellulose mixture) comprises sodium hydroxide for reuse in step a) of the process.

[0043] In this aspect of the invention, cellulose produced from the cellulose pulp derived from the organic acid pretreatment process and stripped of residual organic acids by the drying and desolventization steps described above may still contain residual organic acid levels equivalent to 0.5% to 5% of the total weight of the cellulose. In this aspect of the invention, such cellulose pulp is further treated by a process including neutralization and subsequent alkalization to form alkalized cellulose.

[0044] As shown in FIG. 3, the residual organic acids contained in the cellulose in step a) of the process are neutralized by adding sodium hydroxide liquor recycled from separating the alkalized cellulose from the alkalized cellulose mixture in step d). The pH of the sodium hydroxide liquor is pH 10-pH 12. After adding the sodium hydroxide liquor to the cellulose, the pH of the cellulose mixture is adjusted to a range of 5-8 by adding more sodium hydroxide as needed. The use of sodium hydroxide liquor recycled from the last step of the process to produce alkalized cellulose can reduce the overall consumption of sodium hydroxide by 30%-65% by weight compared to the current treatment process.

[0045] In step b), the neutralized cellulose is separated from the neutralized cellulose mixture by use of a press. The press may be a screw press or other type of press known to those skilled in the art. In this separation step, the neutralized cellulose mixture formed in step a) is separated into two streams, one containing the neutralized cellulose and the other containing the filtrate. The neutralized cellulose has a dry solids content of 30% to 45%. The filtrate is discharged directly to the wastewater treatment system, and since the pH of the filtrate is between pH5 and pH8, there is no need to adjust the pH by titration as in existing treatment processes.

[0046] In step c), the neutralized cellulose is alkalized to a pH of pH 10 to pH 12 by adding a sodium hydroxide solution at a temperature of 50° C. to 100° C. in a reactor. Under these conditions, the lignin content in the cellulose can be reduced to a level of 1% to 2.5% calculated from the total weight of the cellulose.

[0047] In step d), the alkalized cellulose mixture is separated by use of a press. In this separation step, the alkalized cellulose mixture is separated into two streams, one stream containing the alkalized cellulose and the other stream containing the sodium hydroxide solution.

[0048] The alkalized cellulose contains a dry solid content of 30% to 45% calculated from the total weight of the alkalized cellulose. After the washing step, the alkalized cellulose may be hydrolyzed by cellulase, which has a high conversion rate of cellulose to glucose.

[0049] The sodium hydroxide solution can be recycled to step a) to neutralize the organic acid.

[0050] Production of pure lignin This aspect of the invention is a process for separating and cleaning lignin from a lignin suspension by sedimentation and centrifugation, comprising: a) separating lignin from a lignin suspension produced from an organic acid pretreatment of plant material by batch or continuous centrifugation; b) cleaning the precipitated lignin in the centrifuge by applying a wash solution onto the lignin layer multiple times during centrifugation to form a plurality of centrates; c) collecting the first centrate and the second centrate for use in hemicellulose juice concentration; d) recycling the third centrifuged product to precipitate the lignin in the concentrated extract into the lignin suspension of the organic acid pretreatment process; e) discharging the lignin from the centrifuge.

[0051] The extract of this aspect of the invention is obtained from an existing organic acid pretreatment process in which the hemicellulose and lignin contained in the plant material are dissolved in an organic acid solution from which the extract is derived. The extract is separated from the mixture and the extract containing cellulose, dissolved hemicellulose, lignin, minerals, organic acids, water, and other trace components is concentrated by an evaporation system to remove a portion of the organic acids and water to a dry matter content of 55% to 65% calculated from the total weight of the concentrated extract.

[0052] According to the invention, the separation apparatus is a centrifuge, preferably a scraper centrifuge, which can be run in continuous or batch mode. The centrifuge is equipped with a spraying device that allows to spray washing water evenly onto the lignin layer to obtain pure lignin.

[0053] As shown in Figure 4, the third centrate from step d) is mixed with the concentrated extract to form a mixture, the mixture is fed to a suspension tank to form a stable lignin suspension, and the mixture is emulsified by using a continuous or batch emulsifier in the suspension tank. The lignin suspension is then fed continuously to a centrifuge, and the centrate is then separated from the lignin suspension to obtain a first centrate and a lignin layer. The first centrate, constituting 10%-60% of the total volume of the centrate, is collected for further processing by a hemicellulose juice generating unit.

[0054] The spraying device delivers wash water, which may include a mixture of formic acid, acetic acid, and water, providing an online cleaning of the lignin layer. In a preferred embodiment, the centrifuge rotates continuously. The wash water can be sprayed evenly onto the lignin layer under continuous rotation to provide homogenous cleaning of the lignin. During spraying, impurities are washed away by the wash water, and the recovered wash water and impurities form a second centrate, constituting 10% to 30% by volume of the total centrate. The operation of the centrifuge continues while applying subsequent washes to generate a third and possibly more centrates. The third and subsequent centrates may constitute 10% to 50% by volume of the total centrate. Once the final centrate is removed, the lignin layer is discharged from the centrifuge to obtain pure lignin containing 90% to 99% by weight of lignin.

[0055] The wash water may comprise water or a mixture of formic acid, acetic acid, and water, where the formic acid content of the mixture is between 0% and 30% calculated from the total weight of the mixture, and the acetic acid content of the mixture is between 0% and 20% calculated from the total weight of the mixture. The mixture of formic acid, acetic acid, and water may be derived from organic acids recovered from a high water content organic acid solution by an acid distillation unit. In a preferred embodiment, the first wash water introduced into the centrifuge is derived from a high organic acid content wash water. In some embodiments, the second wash water introduced into the centrifuge is derived from a low organic acid content wash water. In some embodiments, the unused water constitutes the wash water for the third and any subsequent wash steps to clean the lignin layer to obtain pure lignin.

[0056] The first and second centrifuges can be collected and delivered to a subsequent hemicellulose juice production unit, while the third and any subsequent centrifuges can be recycled to the lignin suspension step to reduce water consumption for the initial lignin precipitation step and, consequently, reduce energy consumption of the hemicellulose juice production and organic acid recovery units.

[0057] Production of hemicellulose juice This aspect of the invention is a process for producing hemicellulose juice by a combination of evaporation and stripping, comprising: a) introducing a hemicellulose mixture, which is composed of dissolved hemicellulose produced by organic acid pretreatment of a plant material, organic acids, water, and the like, into a multiple effect evaporation system; b) evaporating the hemicellulose mixture in a multiple effect evaporator to form a concentrated hemicellulose juice having a dry matter content of 40% to 70% (w / w); and c) removing organic acids from the concentrated hemicellulose juice in a stripping column to form a hemicellulose juice, the hemicellulose juice containing less than 2% (w / w) organic acids.

[0058] The present invention is based on existing organic acid pretreatment processes of plant materials in which a mixture of formic acid and acetic acid or formic acid alone is used to dissolve hemicellulose and lignin from lignocellulosic plant raw materials and after an initial separation step, an extract containing dissolved hemicellulose, lignin, organic acids, water and other minor components is separated from the remaining insoluble material (which mainly contains cellulose).

[0059] After the lignin precipitation, filtration, and washing steps, the lignin is removed from the extract and the residue, known as the hemicellulose juice, is composed of dissolved hemicellulose, organic acids, water, and trace amounts of other water-soluble components.

[0060] The dissolved hemicellulose in hemicellulose juice is composed primarily of xylose and arabinose, which can be used to produce ethanol and other industrial products. Residual organic acids in the hemicellulose juice can inhibit the conversion of xylose and arabinose to ethanol and other industrial products. In addition, such organic acids represent costly reagent losses in the overall organic acid pretreatment process. This aspect of the invention specifically relates to the production of hemicellulose with minimal residual organic acids suitable for optimal conversion to ethanol by a process that can simultaneously recover such organic acids present in the hemicellulose juice for use in the organic acid pretreatment process.

[0061] The content of dissolved hemicellulose in the hemicellulose juice is between 2% and 20%, calculated from the total weight of the hemicellulose mixture. The content of organic acids in the hemicellulose juice is between 10% and 30%, calculated from the total weight of the hemicellulose mixture. Step a) of the present invention is characterized by a multiple effect evaporation system for partially evaporating the organic acids together with the water to a dry matter content of between 40% and 70%, calculated from the total weight of the concentrated hemicellulose juice.

[0062] Multiple-effect evaporation can reduce steam / energy consumption to remove organic acids and concentrate hemicellulose juice. In some embodiments, multiple-effect evaporation is characterized by the use of a 2-4 effect evaporation system as shown in Figures 6-8. In a preferred embodiment, the process uses a triple effect evaporation system.

[0063] In some embodiments, the multiple effect evaporation of the organic acid with water is carried out in the first effect evaporator at a temperature between 60° C. and 160° C. In some embodiments, the multiple effect evaporation of the organic acid with water is carried out in the last effect evaporator at a temperature between 25° C. and 60° C.

[0064] The first evaporator in the multiple effect evaporation system may utilize the steam discharged from the top of the stripping column completely as a thermal energy source, or partially as a thermal energy source. Each step in the multiple effect evaporation system may utilize the steam discharged from the top of the previous evaporator as thermal energy to drive the next column, reducing the overall energy required by the multiple effect evaporation system.

[0065] As shown in FIGS. 6 to 8, the hemicellulose mixture is supplied to a first evaporator and sequentially discharged from the first evaporator.

[0066] After concentrating the hemicellulose juice by the multi-effect evaporation system, the dry matter content of the concentrated hemicellulose juice discharged from the first evaporator is 40%-70% of the total weight of the concentrated hemicellulose juice, and the viscosity of the concentrated hemicellulose juice is 200mPas-1000mPas. If the viscosity of the concentrated hemicellulose juice is higher than this range, it is very difficult to further remove organic acids by evaporation.

[0067] The present invention further features a combination of a multi-effect evaporation system and a stripping column, in which the concentrated hemicellulose juice discharged from the multi-effect evaporation system is fed to the top plate of the stripping column, which utilizes direct steam as a stripping medium to further remove organic acids to a content of less than 2% of the total weight of the stripped hemicellulose juice.

[0068] The vapor discharged from the top of the stripping column can be used as heat energy for the first evaporator of a multiple effect evaporation system.

[0069] The stripped hemicellulose juice discharged from the bottom of the stripping column is used as the end product, ie, hemicellulose juice, which can be used to produce ethanol and other industrial products.

[0070] Removal of water from aqueous organic acid solutions This aspect of the invention is a process for recovering organic acids from high water content organic acid solutions by multi-column distillation, comprising: a) adopting a 2-5 column distillation system to recover organic acids; b) supplying unused steam only to a first column of a multi-column distillation system, the other columns sequentially utilizing the steam released from the previous column as heat energy; c) directing the vapor discharged from the previous column as heat energy to the subsequent column, whereby the vapor discharged from the first column is fed to the second column, the vapor discharged from the second column is fed to the third column, and so on through each column of the distillation system to the subsequent columns; d) feeding one or more high water content organic acid solution streams to different columns in a multi-column system to balance the energy requirements of the column with the distillation system; e) adjusting the content of organic acids in the condensate of the first column to minimize unused steam consumption; f) recycling the total organic acids and total water discharged from the multi-column distillation system.

[0071] In this aspect of the invention, a high-water content organic acid solution is obtained from an organic acid pretreatment process of plant material. Typically, the organic acid content constitutes more than 83% of the total weight of the solution. Typically, during the organic acid pretreatment process, and as a result of the downstream steps of cellulose pulp processing and lignin and hemicellulose sugar production at relatively low temperatures and atmospheric pressure, furfural is not produced during the entire pretreatment process, leading to the production of four high-water content organic acid solution streams. In order to recycle the organic acid in the high-water content organic acid stream to the organic acid pretreatment process, the water content needs to be reduced.

[0072] Recovery of organic acids from high water content organic acid solutions by distillation requires very high energy input, therefore, reducing the energy required for organic acid recovery and recycling is essential to commercialize the organic acid pretreatment process.

[0073] In one embodiment, the present invention features the recovery of organic acids from high water content organic acid solutions by using a 2-5 column distillation system to maximize energy efficiency. A preferred embodiment uses a 4 column distillation system.

[0074] The more columns there are, the less steam / energy is consumed by the distillation system. However, the number of columns that the distillation system comprises is limited by the temperature difference between the columns of the distillation system. Surprisingly, it has been found by experience that when a system includes more than five columns, the temperature difference between the columns is too small to use the steam released from the previous column as steam / energy for the next consecutive column.

[0075] After scientific analysis, in this process, a 2-5 column distillation system may be suitable for recovering organic acids from high water content organic acid solution, and 4 column distillation is most suitable from the viewpoint of efficiency and economy.

[0076] Typically, the organic acid pretreatment process produces four streams of high-water organic acid solution as described above. The term "high-water organic acid solution" means that the water content is higher than that required in the organic acid solution used to dissolve the plant material in the organic acid pretreatment process. Therefore, additional water, which is added throughout the various process steps to recycle the organic acids from the four high-water organic acid streams, needs to be removed. To minimize the amount of steam / energy required to recover the organic acids from the high-water organic acid solution by multi-column distillation, the steam / energy used in each column needs to be adjusted to suit the level of organic acids in each successive column.

[0077] The present invention achieves this by employing two methods. First, energy input is properly directed throughout the system by feeding the highest water content organic solution to the last column of the distillation system and the lowest water content organic acid solution to the first column of the distillation system. Second, adjusting the amount of steam / energy introduced to the first column allows for balancing of steam / energy consumption throughout the entire distillation system by adjusting the organic acid content of the condensate exiting the top of the first column to 0.5%-10% of the total weight of the condensate. The 0.5%-10% organic acid content of the first column condensate can be diverted for use in the lignin precipitation step of the lignin production process.

[0078] In the systems described herein, a series of other columns typically produce condensates with an organic acid content of 0.2% to 1% of the total weight of condensate injected. These condensates can be recycled to the pretreatment process to wash the lignin, and to other steps in the lignin production process.

[0079] To maintain an optimal temperature differential between the columns, the first column is operated at a temperature between 120°C and 175°C and the last column is operated at a temperature between 50°C and 95°C.

[0080] The organic acid solutions discharged from the bottom of the first column have a water content of 5%-15% calculated from the total weight of the organic acid solutions, and these organic acid solutions can be directly reused in the organic acid pretreatment process for the first step of solubilizing plant raw materials.

[0081] organic fertilizer This embodiment of the invention depicted in FIG. 14 is a method for producing organic fertilizer from stillage produced from cellulosic and hemicellulose juices, comprising: a) separating stillage from cellulose and hemicellulose juices produced by organic acid pretreatment of plant material using a decanter to obtain a stillage solid fraction and a thin stillage; b) concentrating the lean stillage using a multiple-effect evaporation system to obtain a concentrated stillage, the steam for the multiple-effect evaporation system being supplied from the steam discharged from the dryer in step d) of the process, and optionally supplemented with unused steam; c) mixing the solid fraction with the concentrated stillage to obtain a mixture; and d) drying the mixture to obtain an organic fertilizer, wherein the steam discharged from the dryer is supplied to a multiple effect evaporation system of the process as heat energy for the multiple effect evaporation system.

[0082] The present invention is based on the existing organic acid pretreatment process. In the pretreatment process, an organic acid solution is used as an extraction reagent to dissolve most of the lignin, hemicellulose, salts (mainly potassium salts and phosphates), proteins, and other components of the lignocellulosic plant material. The pretreatment mixture is separated into an insoluble cellulose pulp and a mixture of hemicellulose juice and lignin. The cellulose pulp is dried to obtain cellulose. The mixture of hemicellulose juice and lignin is separated into hemicellulose juice (containing hemicellulose, salts, proteins, and other soluble components) and lignin. After hydrolysis and fermentation of the cellulose and hemicellulose juice, most of the cellulose and hemicellulose contained in the hemicellulose juice is converted into ethanol. After extraction of ethanol from the fermented cellulose and hemicellulose juice by distillation, the residue of the fermented cellulose and hemicellulose juice is discharged from the bottom of the mash column of the distillation system. The residue is the distillation waste (a by-product of the process).

[0083] The distillery effluent contains many nutritional components from the lignocellulosic raw material (protein, potassium, phosphorus, calcium, magnesium, sodium, aluminum, etc.), as well as additional nutritional components, including yeast, secondary metabolites produced by the growth of the yeast during fermentation, and residual yeast growth medium containing significant amounts of nitrogen, potassium, phosphorus, and organic matter. Such materials represent all the requirements of an organic fertilizer. Organic fertilizers are fertilizers derived from animal matter, animal waste (feces), human waste, and plant matter (e.g., compost and crop residues); in contrast, the majority of fertilizers used in commercial agriculture are chemical fertilizers (e.g., ammonia) extracted from minerals (e.g., phosphate rock) or produced industrially. Organic agriculture as a system of farm management allows the use of certain fertilizers and soil improvement substances and prohibits others. Both organic and chemical fertilizers can provide a significant increase in plant yields, however, organic fertilizers have a more complete mineral profile and cannot cause the kind of soil damage that can be caused by chemical fertilizers. Organic fertilizers are an important developing direction for agriculture.

[0084] In one embodiment, the process disclosed herein produces organic fertilizer using agricultural residues as a raw material and distillery effluent produced in part by hydrolysis of cellulose and hemicellulose recovered from the agricultural residues and fermentation of sugars released by the hydrolysis of cellulose and hemicellulose by yeast.

[0085] The method is characterized in that the distillation effluent is obtained from the bottom of the mash column of an ethanol distillation system. The dry matter content is between 2% and 20% calculated from the total weight of the distillation effluent. In one embodiment, a centrifuge is used to separate the distillation effluent into a solid fraction and a thin distillation effluent fraction. In a preferred embodiment, the centrifuge is a decanter centrifuge.

[0086] After separation, the dry matter content of the solid fraction is 20%-45% calculated from the total weight of the solid part of the stillage. The dry matter content of the thin stillage fraction is 1%-15% calculated from the total weight of the thin stillage.

[0087] The thin distillation effluent can be concentrated by a multiple effect evaporation system. The multiple effect evaporation system can include a 4-6 effect evaporation system. In a preferred embodiment, the multiple effect evaporation is a 5-effect evaporation system. In a multiple effect evaporation system, the steam discharged from the top of the previous evaporator is utilized as heat energy for the next evaporator to minimize the total energy of the multiple effect evaporation system. The thin distillation effluent is fed to the last evaporator of the multiple effect evaporation system and discharged from the first evaporator of the multiple effect evaporation system. The multiple effect evaporation system is run at a temperature between 30°C and 150°C.

[0088] After concentration, the dry matter content of the concentrated stillage is 28%-45% calculated from the total weight of the concentrated stillage.

[0089] The condensate of the steam separated in the multiple effect evaporation system obtained in step b) can be reused as process water.

[0090] The solid portion and the concentrated stillage are fed to a mixer, and the two portions are mixed to obtain a mixture of solid fraction and concentrated stillage. The mixture of solid portion and concentrated stillage is dried by a dryer, preferably a tube dryer, to obtain an organic fertilizer. The dryer is operated at a temperature of 80°C to 160°C. The dry solid content of the organic fertilizer is 50% to 80% calculated from the total weight of the organic fertilizer. The steam discharged from the dryer can be fed to the stillage multiple effect evaporation system to provide heat energy to the multiple effect evaporation system. After drying, the mixture of solid portion and concentrated stillage is dried, and the dried mixture can be used as an organic fertilizer.

[0091] Organic fertilizers contain organic matter, protein, potassium salts, phosphates, mineral matter, etc. The organic matter content of organic fertilizers is 30%-65% calculated from the total dry matter of the organic fertilizer. The total nutrient content of organic fertilizers (calculated based on the formula: nutrients = nitrogen + phosphorus pentoxide + potassium oxide) is 5%-30% calculated from the total dry matter of the organic fertilizer. The pH value of organic fertilizers is 5.5-8.5. The moisture content of organic fertilizers is 20%-50% calculated from the total weight of the organic fertilizer. EXAMPLES

[0092] Example 1 Recovery of organic acids from cellulose pulp. Corn straw was used as the lignocellulosic raw material. The cellulose pulp was obtained following an organic acid pretreatment process. The organic acid composition is 26% formic acid, 59% acetic acid content, and 15% water, the temperature is 103°C, and the solvation time is 240 min. After separation, the cellulose pulp is separated from the liquid fraction.

[0093] Approximately 5 kg of cellulose pulp was recovered, and the dry matter content was 38.0%, the organic acid content was 49.5%, and the moisture content was 12.5%, calculated from the total weight of the cellulose pulp. The cellulose pulp was fed into a dryer to obtain dried cellulose pulp, and the drying temperature was 120° C. After drying, the organic acid content of the dried cellulose pulp was 5.5%.

[0094] The dried cellulose pulp was introduced into a desolventizer with a feed flow rate of 200 g / min, direct steam was introduced into the bottom of the desolventizer, the temperature of the steam was 120° C., and the flow rate of the direct steam feed to the desolventizer was 14.1 g / min. The desolventized cellulose pulp was discharged from the desolventizer.

[0095] The organic acid content of the desolventized cellulose pulp was 1.8%, calculated from the total weight of the desolventized cellulose pulp.

[0096] A second cellulose pulp derived from corn straw was prepared under similar conditions as above. However, in this test, the dryer temperature was slightly lower (110° C.), but the steam flow rate in the desolventizer was increased to 26.3 g / min. The desolventized cellulose pulp produced under these conditions had an organic acid content of 1.95%.

[0097] In the third study, wheat straw was used as the lignocellulosic raw material and cellulose pulp was obtained following the organic acid pretreatment process mentioned above.

[0098] Approximately 5 kg of cellulose pulp was recovered, and the dry matter content was 37.5%, the organic acid content was 50.2%, and the moisture content was 12.3%, calculated from the total weight of the cellulose pulp. The cellulose pulp was fed into a dryer to obtain a dried cellulose pulp, and the drying temperature was 115° C. After drying, the organic acid content of the obtained dried cellulose pulp was 6.7%.

[0099] The dried cellulose pulp was introduced into a desolventizer with a feed flow rate of 200 g / min, direct steam was introduced into the bottom of the desolventizer, the temperature of the steam was 120° C., and the flow rate of the direct steam feed to the desolventizer was 16.8 g / min. The desolventized cellulose pulp is discharged from the desolventizer.

[0100] The desolventized cellulose pulp produced under these conditions had an organic acid content of 1.91%.

[0101] Table 1 summarizes these data. [Table 1]

[0102] Example 2 Neutralization and alkalization of cellulose Sample 1 Method A: Initially, 0.4 kg of cellulose (lignin content was 4.1% and organic acid content was 1.56%) was fed into the reactor, the agitator was started, the pH was adjusted to 12 with sodium hydroxide solution, to which 3.34 L of additional water was added. The temperature of the reactor was maintained at 80° C. and the reaction was continued for 60 minutes.

[0103] When the reaction was completed, 9.16 g of sodium hydroxide had been consumed and the lignin content of the treated cellulose was 1.89%.

[0104] Method B: In the first neutralization step of the first treatment run, 0.4 kg of cellulose (lignin content was 4.1% and organic acid content was 1.56%) was fed to the reactor, the agitator was started, the pH was adjusted to pH 6.5 with sodium hydroxide solution, to which 3.34 L of additional water was added. The reactor temperature was maintained at 80° C. and the reaction was allowed to continue for 30 minutes. Following the reaction, the cellulose mixture was filtered and pressed.

[0105] In the alkalinization step, the neutralized cellulose was added to the alkalinization reactor, the agitator was started, and the pH was adjusted to pH 12 with sodium hydroxide solution, to which 3.34 L of additional water was added. The temperature of the reactor was maintained at 80° C., and the reaction continued for 30 minutes. Sodium hydroxide was added as necessary to maintain the pH at pH 12. After 30 minutes, the alkalinized cellulose mixture was filtered and pressed to obtain sodium hydroxide solution and alkalinized cellulose. The sodium hydroxide solution may be reused in the neutralization step of the second (subsequent) treatment operation.

[0106] In the second treatment run, 0.4 kg of cellulose (having a lignin content of 4.1%, an organic acid content of 1.56%) was fed into the neutralization reactor, the agitator was started, the pH was adjusted to pH 6.8 using sodium hydroxide liquor recovered from the alkalinization step of the first treatment run, the reactor temperature was maintained at 80° C., and the reaction was allowed to continue for 30 minutes. Following the reaction, the cellulose mixture was filtered and pressed.

[0107] The alkalization step of the second (and subsequent) treatment runs included the same steps as those described for the first round. Importantly, the sodium hydroxide liquor recovered after filtering and pressing the alkalized cellulose can be reused in the neutralization step of the next treatment run. In the second round of treatment utilizing sodium hydroxide recovered from the first round, the total sodium hydroxide consumed was 4.58 g and the lignin content of the treated cellulose was 1.85%.

[0108] Sample 2 Method A: Initially, 0.4 kg of cellulose (lignin content was 3.6% and organic acid content was 2.68%) was fed into the reactor, the agitator was started, the pH was adjusted to 12 with sodium hydroxide solution, to which 3.34 L of additional water was added. The temperature of the reactor was maintained at 80° C. and the reaction was continued for 60 minutes.

[0109] When the reaction was completed, 12.4 g of sodium hydroxide had been consumed and the lignin content of the treated cellulose was 1.56%.

[0110] Method B: In the first neutralization step of the first treatment run, 0.4 kg of cellulose (lignin content was 3.6% and organic acid content was 2.68%) was fed to the reactor, the agitator was started, the pH was adjusted to pH 6.5 with sodium hydroxide solution, to which 3.34 L of additional water was added. The reactor temperature was maintained at 80° C. and the reaction continued for 30 minutes. Following the reaction, the cellulose mixture was filtered and pressed.

[0111] In the alkalinization step, the neutralized cellulose was added to the alkalinization reactor, the agitator was started, and the pH was adjusted to pH 12 with sodium hydroxide solution, to which 3.34 L of additional water was added. The temperature of the reactor was maintained at 80° C., and the reaction was continued for 30 minutes. Sodium hydroxide was added as necessary to maintain the pH at pH 12. After 30 minutes, the alkalinized cellulose mixture was filtered and pressed to obtain sodium hydroxide solution and alkalinized cellulose. The sodium hydroxide solution may be reused in the neutralization step of the subsequent processing operation.

[0112] In the second treatment run, 0.4 kg of cellulose (having a lignin content of 3.6%, an organic acid content of 2.68%) was fed into the neutralization reactor, the agitator was started, the pH was adjusted to pH 6.8 using sodium hydroxide liquor recovered from the alkalization step of the first treatment run, the reactor temperature was maintained at 80° C., and the reaction was allowed to continue for 30 minutes. Following the reaction, the cellulose mixture was filtered and pressed.

[0113] The alkalization step of the second (subsequent) treatment run included the same steps as those described for the first round. Importantly, the sodium hydroxide liquor recovered after filtering and pressing the alkalized cellulose can be reused in the neutralization step of the next treatment run. In the second round of treatment utilizing sodium hydroxide recovered from the first round, the total sodium hydroxide consumed was 7.87 g, and the lignin content of the treated cellulose was 1.58%.

[0114] Sample 3 Method A: Initially, 0.4 kg of cellulose (lignin content was 3.8% and organic acid content was 4.52%) was fed into the reactor, the agitator was started, the pH was adjusted to pH 12 with sodium hydroxide solution, to which 3.34 L of additional water was added. The temperature of the reactor was maintained at 80° C. and the reaction continued for 60 minutes.

[0115] When the reaction was completed, 17.9 g of sodium hydroxide had been consumed and the lignin content of the treated cellulose was 1.66%.

[0116] Method B: In the first neutralization step of the first treatment run, 0.4 kg of cellulose (lignin content was 3.8% and organic acid content was 4.52%) was fed to the reactor, the agitator was started, the pH was adjusted to 6.5 with sodium hydroxide solution, to which 3.34 L of additional water was added. The reactor temperature was maintained at 80° C. and the reaction was allowed to continue for 30 minutes. Following the reaction, the cellulose mixture was filtered and pressed.

[0117] In the alkalinization step, the neutralized cellulose was added to the alkalinization reactor, the agitator was started, and the pH was adjusted to pH 12 with sodium hydroxide solution, to which 3.34 L of additional water was added. The temperature of the reactor was maintained at 80° C., and the reaction was continued for 30 minutes. Sodium hydroxide was added as necessary to maintain the pH at pH 12. After 30 minutes, the alkalinized cellulose mixture was filtered and pressed to obtain sodium hydroxide solution and alkalinized cellulose. The sodium hydroxide solution may be reused in the neutralization step of the subsequent processing operation.

[0118] In the second (subsequent) treatment run, 0.4 kg of cellulose (having a lignin content of 3.8%, an organic acid content of 4.52%) was fed to the neutralization reactor, the agitator was started, the pH was adjusted to pH 7.1 using sodium hydroxide liquor recovered from the alkalinization step of the first treatment run, the reactor temperature was maintained at 80° C., and the reaction was allowed to proceed for 30 minutes. Following the reaction, the cellulose mixture was filtered and pressed.

[0119] The alkalization step of the second (subsequent) treatment run included the same steps as those described for the first round. Importantly, the sodium hydroxide liquor recovered after filtering and pressing the alkalized cellulose can be reused in the neutralization step of the next treatment run. In the second round of treatment utilizing sodium hydroxide recovered from the first round, the total sodium hydroxide consumed was 13.3 g and the lignin content of the treated cellulose was 1.63%.

[0120] Table 2 summarizes these sample data. [Table 2]

[0121] Example 3 Lignin formation The extract was obtained from the organic acid pretreatment process, and the composition of the organic acid in the pretreatment consisted of 26% formic acid, 59% acetic acid, and 15% water. The pretreatment temperature was 103°C, and the pretreatment extraction duration was 240 min. After separation, the extract was separated from the solid fraction, and the extract was concentrated by evaporation to obtain a concentrated extract. The dry matter content of the concentrated extract was 60.1%, and the lignin content was 29.5% (other components of the concentrated extract are listed in Table 3).

[0122] 1.40 kg of the concentrated extract was combined with an equal weight of fresh water (1.40 kg) and an emulsifier (SHW300R Lab Emulsifier, Shanghai Shenghaiwei Electric Instruments Co., Ltd) was used to generate a lignin suspension operating at 7500 rpm for approximately 30 minutes. The lignin suspension was introduced into a centrifuge and centrifuged for 5 minutes to obtain a first centrate (2.05 kg liquid) and a solid lignin layer. The first centrate was removed from the centrifuge.

[0123] 1.94 kg of washing water was fed to the spray device to wash the lignin layer in the centrifuge. The washing water in the procedure includes water and a mixture of formic acid, acetic acid, and water. When feeding washing water to the centrifuge, it was found that using a first feed of 0.54 kg of high organic acid-containing washing water with an organic acid content of 5.92%, a second wash consisting of 1.00 kg of low organic acid-containing washing water with an organic acid content of 0.8%, and a final wash consisting of 0.40 kg of unused water, sufficiently washed the lignin layer to obtain pure lignin.

[0124] Following the first centrifugation and discharge of the first centrate, the centrifuge was continued to operate for 5 minutes, during which a first wash was performed with high organic acid water, yielding a second centrate (0.54 kg). The centrifuge was operated for another 5 minutes, during which a second wash was performed with low organic acid water, yielding a third centrate of 1.40 kg. After a subsequent third wash with fresh water, a lignin layer containing 0.75 kg was obtained. The first and second centrates were collected and may be incorporated into a subsequent hemicellulose juice production unit operation. The dried lignin was discharged from the centrifuge, and the purity of the lignin was determined to be 98.1% (lignin components at each stage of operation are shown in Table 3). [Table 3]

[0125] The third centrifugate from above (1.40 kg) was recycled for use as a diluent for the concentrated extract to produce a lignin suspension using the SHW 300R lab emulsifier described above. The resulting lignin suspension was introduced into a centrifuge, which was operated as described above to obtain a lignin layer of approximately 0.75 kg.

[0126] In this operation, the first wash consisted of 0.54 kg of high organic acid content wash water, which had an organic acid content of about 10%. The second wash consisted of 1.00 kg of low organic acid content wash water, which had an organic acid content of about 2%, and the final wash consisted of 0.40 kg of unused water. All centrifugation operations and conditions were carried out as described above. As before, the first and second centrates may be recycled for use in subsequent hemicellulose juice production unit operations. At the end of the operation, the lignin is discharged from the centrifuge. In this case, the purity of the lignin was 97.2% (the constituents of the lignin at each operation stage are shown in Table 4). [Table 4]

[0127] Again, the third centrate (1.40 kg) from the above operation was recycled to dilute the concentrated extract and processed in a SHW 300R lab emulsifier to produce a lignin suspension. The resulting lignin suspension was introduced into a centrifuge, which was operated as described above to obtain a lignin layer.

[0128] In this operation, the first wash consisted of 0.54 kg of high organic acid content wash water with an organic acid content of 5.92. The second wash consisted of 1.00 kg of low organic acid content wash water with an organic acid content of 0.8%, and the final wash consisted of 0.79 kg of unused water. All centrifugation operations and conditions were carried out as described above. As before, the first and second centrates may be recycled for use in subsequent hemicellulose juice production unit operations. At the end of the operation, the lignin is discharged from the centrifuge. In this case, the purity of the lignin was 98.8% (the components of the lignin at each operation stage are shown in Table 5). [Table 5]

[0129] Example 4 Hemicellulose juice processing A concentrated hemicellulose mixture was obtained from the initial hemicellulose mixture (dry matter content 16.4%, formic acid 6.0%, acetic acid 14.4%, and water 63.2%) containing dissolved hemicellulose, organic acid water, and other soluble components by using an evaporator (100 mm diameter, 2 m height) using indirect steam to heat the evaporator to evaporate organic acids and water from the hemicellulose mixture.

[0130] The flow rate of the hemicellulose mixture into the evaporator was 10.0 kg / hr, with an indirect steam flow rate of 6.2 kg / hr and an evaporation temperature of 90° C., producing a flow rate of 2.96 kg / hr of concentrated hemicellulose mixture. The dry matter content of the concentrated hemicellulose mixture produced under these conditions was 55.6%. The acid content of the concentrated hemicellulose mixture was 16.5%.

[0131] The resulting concentrated hemicellulose mixture was fed to the top of a stripping column (100 mm diameter, 2.5 m height) and direct steam was fed to the bottom of the stripping column, which served to partially strip the organic acids present in the concentrated hemicellulose into the direct steam. This produced a stripped hemicellulose mixture. The stripping specifications were adjusted to a direct steam flow rate of 1.51 kg / hr and a direct steam temperature of 105°C, producing a flow rate of 2.46 kg / hr of stripped hemicellulose mixture. The dry matter content of the stripped hemicellulose mixture was 60.4%. The acid content of the stripped hemicellulose mixture was 1.64%.

[0132] Based on the regression of the vapor-liquid equilibrium with the experimental data described above, the evaporation and stripping process was modeled using Aspen Plus software (Aspen Technology, Inc., Massachusetts, USA), allowing several different operating parameters to be explored.

[0133] The model parameters described above were used to simulate the conditions and performance of two-, three-, and four-effect evaporation and stripping systems for concentrations of dissolved hemicellulose, organic acids, and hemicellulose mixtures containing water, as well as other components.

[0134] Flowsheets for the two-, three-, and four-effect evaporation and stripping systems were constructed for use in Aspen Plus software and are shown in Figures 6-8, respectively. In these models, the hemicellulose mixture (21), which contains dissolved hemicellulose, organic acids, water, and other components, is evaporated by evaporator II and evaporator I to obtain concentrated hemicellulose juice (22). The concentrated hemicellulose juice (22) is fed to the top of the stripping column (102), and unused steam (26) is fed to the bottom of the stripping column (102) to obtain stripped hemicellulose juice (24). The steam discharged from the top of the stripping column and additional unused steam (27) are used as heat resources for evaporator I, and the steam discharged from the top of the stripping column and additional unused steam (27) condensed in evaporator I are recovered as condensed acid II (25). The vapor from evaporator I is used as the heat source for evaporator II, while the vapor from evaporator I that is condensed in evaporator II serves as condensed acid I (23). The same scenario involving using the vapor initially recovered from the stripping column for evaporator I and using the vapor recovered from evaporator I to serve as the heat source for evaporator II also applies to systems that include additional multiple effect evaporator units, as shown in FIG. 7 for a triple effect evaporator system and FIG. 8 for a quadruple effect evaporator system, where unused vapor is not needed in FIG. 7 for the triple effect evaporator system, and vapor (28) from the stripping column in excess of the vapor needed for the quadruple effect evaporator system is discharged from the top of the stripping column and used for other systems.

[0135] The following table presents a number of observed and predicted parameters for each of the multiple effect evaporator systems described herein. [Table 6] [Table 7] [Table 8] [Table 9]

[0136] Example 5 Recovery of organic acids from organic acid solutions with high water content A highly hydrous organic acid solution (27.6% formic acid, 51.5% acetic acid, and 20.9% water) was fed at a flow rate of 4.0 kg / h to a distillation column (90 mm diameter, 3 m height, packed column) operated at 1 atm, with a heat duty of 12.6 MJ / h, a reflux ratio of 13.0. Under these conditions, a condensate of the vapor leaving the top of the column was produced at a flow rate of 0.41 kg / h, consisting of 0.27% formic acid, 4.07% acetic acid, and 95.66% water. A distilled organic acid solution leaving the bottom of the column was obtained at a flow rate of 3.59 kg / h, consisting of 30.7% formic acid, 56.9% acetic acid, and 12.4% water.

[0137] Modeling this process with Aspen Plus software using the parameters mentioned above allows for the simulation of distillation systems containing two, three, four, and five columns for separating water from high water content organic acid solutions. The flowsheets generated by the modeling software are shown in Figures 10-13 for the two-column, three-column, four-column, and five-column distillation systems, respectively.

[0138] The organic acid compositions of the various input streams of high water content organic acid solutions derived from the organic acid pretreatment process are listed in Table 10. [Table 10]

[0139] The basic distillation process of the two-column distillation system is shown in FIG. 10. Three of the four inlet streams are fed to the first distillation column (201). These streams originate from the hemicellulose juice evaporation step (2), the hemicellulose juice stripping step (3), and the high water content organic acid solution (4) from the desolventization step of the cellulose pulp processing. The steam condensate (7) discharged from the top of the first column (201) may be recovered for other unit operations. The concentrated mixture (301) is discharged from the bottom of the first column (201) and fed to column 2 (202). The remaining inlet stream (1) from the extract evaporation step of the lignin production is also fed to column 2 (202). The steam condensate (5) discharged from the top of the second column (202) may be recovered for other unit operations. The distilled organic acid solution (6) is discharged from the bottom of the second column (202). The organic acid content of the various effluent streams of the two-column distillation system is presented in Table 11. [Table 11]

[0140] A similar process corresponding to the process flow within a three-column distillation system is depicted in FIG. 11. In this case, the operation is similar in terms of the inlet and outlet streams of the two-column system described above. In this case, however, the vapor condensates of the first two columns are pooled to form a single outlet stream (7 in FIG. 11), and the distilled organic acid solution discharged from column 2 (302) is fed to a third column (203) where vapor condensate (5) is recovered and further distilled organic acid solution (6) is discharged from the bottom of the third column (203). The organic acid content of the various outlet streams of the two-column distillation system is presented in Table 12. [Table 12]

[0141] Similarly, the corresponding process flow within a four-column distillation system is depicted in Figure 12. The organic acid content of the various effluent streams of the two-column distillation system is presented in Table 13. [Table 13]

[0142] The corresponding process flow within the five-column distillation system is depicted in Figure 13. The organic acid content of the various effluent streams of the five-column distillation system is presented in Table 14. [Table 14]

[0143] According to the simulation flowsheet, steam consumption can be significantly reduced by the number of distillation columns present in the system. Data supporting this observation are presented in Table 15. [Table 15]

[0144] The reduction shown in the heat requirements of the two-column system compared to the three-column system is 27.6%, while the reduction in heat requirements of the four-column system is an even 20% lower than that of the three-column system, resulting in an overall reduction in the required heat requirements of the four-column system to 42% of that of the two-column system.

[0145] Interestingly, the addition of a column provides minimal energy improvement, see Table 16. [Table 16]

[0146] Example 6 organic fertilizer In the first experiment, corn straw was used as a source of lignocellulosic plant material for organic acid treatment using formic and acetic acids to extract hemicellulose and lignin. The mixture of hemicellulose and lignin was separated to obtain a cellulose pulp fraction and an extract. The cellulose pulp was treated to partially eliminate the lignin and washed with water to obtain cellulose. The extract was concentrated to separate the lignin, and after separation of the lignin, the residue was concentrated and stripped to obtain hemicellulose juice. The mixture of cellulose and hemicellulose juice was hydrolyzed and fermented to produce ethanol by adding cellulosic enzymes and yeast, respectively. Ethanol was separated from the fermentation by distillation, and the distillation effluent consisted of the residual material of the distillation.

[0147] The stillage (2113 g with a dry matter content of 9.23%) was fed to a decanter, which after decantation produced 61.4 g of solid fraction (with a dry matter content of 38.0%) and 2051.6 g of thin stillage (with a dry matter content of 8.37%). The thin stillage was evaporated (in an evaporator operated at 110° C.) to obtain 451.6 g of concentrated stillage (with a dry matter content of 38.0%). The solid fraction and the concentrated stillage were combined to obtain a mixture (513.0 g). The mixture was dried in a dryer operated at a temperature of 120° C. to obtain 335.1 g of final organic fertilizer with a dry matter content of 58.2% of the organic fertilizer and a pH of 6.1. The organic fertilizer has a dry matter content of 58.2%, an organic matter content of 47.8% and a total nutrient content of 5.86% (calculated based on the formula nutrients = nitrogen + phosphorus pentoxide + potassium oxide), calculated from the total dry matter.

[0148] In a second test for producing organic fertilizer from stillage, using corn straw as the first injection into the organic acid treatment process, stillage (2113 g with 9.23% dry matter) was fed to a decanter. After decantation, 67.1 g solid fraction (35.5% dry matter content) and 2046 g thin stillage (8.37% dry matter content) were obtained. The thin stillage was evaporated (in an evaporator operated at 105 ° C) to produce 456.7 g concentrated stillage with a dry matter content of 37.5%. The solid fraction and the concentrated stillage were combined to produce 523.8 g of a mixture. The mixture was dried in a dryer operated at 130 ° C to produce 297.7 g of a final organic fertilizer with a pH of 6.0 and a dry matter content of 65.5%. The organic fertilizer contains 47.3% organic matter with a total nutrient content of 5.81% calculated from the total dry matter.

[0149] In the third experiment to produce organic fertilizer from stillage, wheat straw was used as the first injection into the organic acid treatment process, and stillage (1940 g containing 9.38% dry matter) was fed to a decanter. After decantation, 59.5 g solid fraction (37.0% dry matter content) and 1880.5 g thin stillage (8.51% dry matter content) were obtained. The thin stillage was evaporated (in an evaporator operated at 115 ° C) to produce 438.3 g concentrated stillage with a dry matter content of 36.5%. The solid fraction and the concentrated stillage were combined to produce 497.8 g of a mixture. The mixture was dried in a dryer operated at 140 ° C to produce 244.3 g of a final organic fertilizer with a pH of 6.2 and a dry matter content of 74.5%. The organic fertilizer contains 48.5% organic matter with a total nutrient content of 6.12% calculated from the total dry matter.

Claims

[Claim 1] The invention described in the specification.

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