Description:TECHNICAL FIELD
[0001] The present disclosure relates to ethanol production plants. More specifically, the present disclosure pertains to a process and a distillation column system for 2G Ethanol Bio-Refinery with High-Silica-Residues & Moderate-Lignin Laden like Rice Husk-Stalk Feed.

BACKGROUND
[0002] Ethanol production from renewable biomass sources has gained significant attention as an environmentally friendly alternative to fossil fuels. Among the various feedstocks available for bioethanol production, lignocellulosic biomass has proven to be one of the most promising sources. However, lignocellulosic biomass consists of three main components, i.e., cellulose, hemicellulose, and lignin.
[0003] Lignin is a complex, non-sugar-based polymer found in plant cell walls, primarily functioning as a structural support material, providing rigidity and resistance to degradation. However, lignin cannot be used directly as feedstock for ethanol production through microbial fermentation via the enzymatic route, as it is highly resistant to breakdown by most enzymes and microbes. This resistance makes it a significant challenge in bioethanol production, as lignin inhibits both microbial growth and fermentation processes, thereby reducing the overall efficiency and economic viability of bioconversion. Lignin's presence in biomass, as the second most abundant component after cellulose, plays a pivotal role in the economics of biofuels. While it cannot be fermented into ethanol, lignin can be utilized as a valuable source of energy. When burned, lignin generates a substantial amount of heat, making it an excellent feedstock for combined heat and power (CHP) systems. In a bio-refinery, lignin can be used in a sustainable and environmentally friendly manner to produce energy, enhancing the overall efficiency and economic performance of the biofuel production process by contributing to the generation of renewable energy. Thus, while lignin is a barrier to ethanol production, its energy potential makes it an important component of the bio-refinery concept.
[0004] The challenge in bioethanol production from lignocellulosic biomass lies in the efficient conversion of cellulose and hemicellulose into fermentable sugars while minimizing the impact of lignin. Traditionally, pre-treatment processes such as chemical, physical, and biological processes have been employed to break down the lignin and enhance the accessibility of cellulose and hemicellulose. However, these processes often suffer from high energy requirements, the generation of by-products, and the need for expensive chemical reagents. Additionally, the inherent heterogeneity of lignocellulosic biomass and its varying lignin content poses another difficulty. Biomasses with high lignin content are particularly difficult to treat and require more aggressive and costly pre-treatment processes.
[0005] Using high silicaHigh-Silica-Residues & Moderate-Lignin laden Rice Husk-Stalk FeedHigh-Silica-Residues & Moderate-Lignin laden Rice Husk-Stalk Feed for ethanol production presents several challenges that can hinder the efficiency and economic viability of the process. One of the primary issues is the low ethanol yield due to the high lignin content, which acts as a barrier, preventing efficient access to cellulose and hemicellulose, the main sources of fermentable sugars. High silicaresidues further complicate this by containing non-fermentable components, reducing the overall yield of ethanol. The pretreatment process becomes more energy-intensive and costly, as high-lignin feeds require rigorous processs like steam explosion or acid hydrolysis to break down the lignin and release fermentable sugars. This also increases chemical usage, leading to higher operational costs and chemical waste.
[0006] From an economic perspective, the higher production costs associated with pretreatment and waste management make the process less viable compared to using low-lignin feedstocks. Reduced ethanol yields and increased operational costs further impact profitability. Technical limitations, such as scaling challenges and the need for extensive process optimization, add to the difficulties, making consistent and efficient ethanol production from such feedstocks time-consuming and costly. While High-Silica-Residues & Moderate-Lignin laden Rice Husk-Stalk Feed is a promising feedstock due to its high cellulose content, the presence of high silicaresidues and high lignin significantly complicates the process, necessitating advanced technologies and alternative solutions to improve feasibility.
[0007] Second-generation (2G) ethanol production from rice husk-stalk biomass faces significant distillation challenges due to high-silica and moderate-lignin content, which result in entrained silica particles interfering with mass transfer, reducing ethanol purity, excessive dust formation clogging distillation internals, frequent fouling requiring manual cleaning, and silica buildup in the stripping section causing operational disruptions. Traditional distillation columns struggle to separate silica particles efficiently, leading to frequent process interruptions.
[0008] A variety of agricultural residues and energy crops rich in silica and lignin are abundantly available for second-generation (2G) bioethanol production. Rice huskstands out due to its high silica content (15–20%), making it a challenging yet widely available feedstock, especially in rice-producing regions like Asia. Similarly, sugarcane bagasse, wheat straw, and corn stover contain moderate silica (2–5%) and significant lignin (15–25%), offering ample raw material for biorefineries. These biomasses are generated in large quantities annually, with global rice husk production alone exceeding 120 million tons. However, their high silica and lignin content complicates pretreatment and hydrolysis, necessitating advanced processing techniques to improve ethanol yields.
[0009] Beyond crop residues, dedicated energy crops like miscanthus and switchgrass also contain silica (1–4%) and lignin (15–25%), though in lower concentrations than rice husk. Their cultivation on marginal lands ensures sustainable availability without competing with food production. While silica-laden feedstocks like rice husk pose operational challenges in distillation, their widespread availability makes them economically viable for large-scale bioethanol projects.
[0010] Following are the types of some examples of the available biomass having silica and moderate lignin content:
• Rice husk (15–20% silica) dominates, with global production exceeding 120 million tons/year, primarily in Asia (India, China, Vietnam).
• Sugarcane bagasse (2–5% silica) is widely available in tropical regions (India, Brazil, Thailand), yielding 280–700 million tons/year.
• Wheat/barley straw (3–6% silica) contributes significantly in Asia, Europe and North America.
[0011] The processing of silica and lignin-rich biomass for bioethanol production presents several operational challenges. The high silica content leads to fouling in distillation columns. Regionally, different areas leverage their biomass advantages strategically - Asia capitalizes on its rice husk surplus to support decentralized biorefineries, while the Americas effectively integrate bagasse and corn stover with their existing sugar and ethanol industries. India boosts on its agro-economy with 500 MMT of agro residues available across different states and geographical regions for production of 2G Ethanol. India has rolled out National Bio-Fuel Policy (NBP) -2018 to utilize this agro residue and in G-20 summit in New Delhi, India has signed a charter for international Bio-Fuel collaboration via Global Bio-Fuel Alliance (GBA)
[0012] Silica and Lignin-laden stillage, when not effectively managed, can accumulate on the internal components of a distillation tower, particularly on sieve trays where the fractionation liquid flows. The sieve trays play a crucial role in allowing the vapor and liquid to interact, promoting the separation of components based on their boiling points. However, the accumulation of lignin sludge and silica on these trays can significantly disrupt this process. As the sludge builds up, it obstructs the free flow of liquids from the inlet downcomer to an outlet downcomer thereof, which is vital for maintaining the proper distribution of liquid across the tray. This blockage reduces the sieve tray’s efficiency by hindering mass transfer, the process through which components are separated within the distillation column, thus lowering the effectiveness of the distillation process. As a result, the overall performance of the distillation tower deteriorates, leading to less efficient separation and, consequently, lower-quality products.
[0013] Conventional techniques for dealing with silica & lignin accumulation often involve labor-intensive manual cleaning or periodic shutdowns for maintenance. These procedures can be highly disruptive, leading to unscheduled downtimes that interrupt continuous operations. The need for frequent maintenance not only affects production timelines but also incurs significant economic losses, both in terms of lost throughput and the cost of labor and resources required for cleaning. Furthermore, repeated downtime for maintenance can affect the long-term operational efficiency of the system, leading to an overall increase in operational costs and a decrease in profitability. Therefore, the need for an effective and continuous solution to manage lignin-laden stillage is critical in maintaining smooth operations, enhancing distillation efficiency, and reducing the economic impact of manual maintenance processes.
[0014] In light of the above challenges, there is a need in the art for a more efficient solution for producing ethanol from biomass slurries and ethanol broths and ethanol broths that contain low to moderate lignin content and very high silica content.
[0015] To address these issues, this invention introduces an advanced feed tray system featuring a vane-type feed inlet device covered by a liquid curtain from the top donut tray, ensuring effective high silica content removal, improved phase separation, and uninterrupted distillation.
[0016] The present invention addresses these challenges by providing an apparatus and process for the efficient production of ethanol from biomass slurries and ethanol broths that contain high silica & Moderate-Lignin content. By optimizing and modifying the sieve trays, the invention offers a more efficient, cost-effective, and environmentally sustainable solution for bioethanol production. The apparatus also allows for scaling up of bioethanol production from a variety of biomass sources, improving the economic feasibility and sustainability of biofuels as a renewable energy source.

OBJECTS OF THE PRESENT DISCLOSURE
[0017] An object of the present disclosure is to provide an apparatus that efficiently processes biomass slurries and ethanol broths, particularly those with with silica & moderate-lignin content, to produce high yields of ethanol without disruption. The apparatus is optimized to take advantage of reduced silica and lignin-related barriers to enzymatic hydrolysis and fermentation.
[0018] Another object of the present disclosure is to provide an apparatus and process for the production of ethanol from biomass slurry and ethanol broth without the need for excessive energy or harsh chemicals. The process efficiently minimizes silica and lignin interference in distillation column.
[0019] The process is adaptable to varying biomass slurries and ethanol broths with low to moderate lignin content, ensuring consistent ethanol production.
[0020] Another object of the present disclosure is to reduce operational costs in the production of ethanol from biomass, particularly by reducing energy consumption and chemical usage. This makes the apparatus and corresponding process more economically viable and competitive in large-scale commercial bioethanol production.
[0021] Another object of the present disclosure is to provide an environmentally sustainable solution for bioethanol production. The apparatus promotes an environmentally friendly process for ethanol production by reducing the need for chemicals, lowering energy consumption, and minimizing the generation of by-products. By improving the efficiency of ethanol production, the apparatus contributes to the overall sustainability of biofuels as a renewable energy source.
[0022] Another object of the present disclosure is to provide a flexible apparatus that can adapt to varying biomass feedstocks with silica and moderate lignin content. This flexibility allows the apparatus to be used with a wide range of feedstocks, making it scalable and versatile for different industrial applications.
[0023] Another object of the present disclosure is to improve the scalability and efficiency of bioethanol production. The apparatus and corresponding process are capable of being easily scaled up for large-scale bioethanol production while maintaining high efficiency and low operational costs. The scalability of the apparatus of the present disclosure helps meet the growing global demand for biofuels.
[0024] Another object of the present disclosure is to provide a process for the production of ethanol that minimizes waste generation and improves the overall sustainability of bioethanol production. By reducing the need for extensive pre-treatment, chemicals, and energy inputs, the process of the present disclosure seeks to minimize waste generation, contributing to a more sustainable and eco-friendly bioethanol production process.

SUMMARY
[0025] Aspects of the present disclosure relate to an apparatus and a process for producing ethanol from biomass slurries and ethanol broths, particularly those with silica and moderate lignin content. The apparatus and process are designed to efficiently break down biomass slurries and ethanol broths by minimizing the challenges posed by lignin, a complex polymer that hinders ethanol distillation. The apparatus enables the effective pre-treatment of biomass slurries and ethanol broths having with silica and moderate lignin content without requiring excessive energy, harsh chemicals, or complex procedures. The apparatus and process of the present disclosure reduce operational costs and enhance the overall yield of ethanol.
[0026] In an aspect, the present disclosure discloses an apparatus for producing ethanol with a biomass slurry and ethanol broth having with silica and moderate lignin content. The apparatus includes a distillation unit configured to receive and process the biomass slurry and ethanol broth to effectively manage lignin content and undigested high silica residues thereof. The distillation unit includes a heat exchanger configured to boil a liquid at a bottom of the distillation unit to generate vapour traversing in a vertically upward direction within the distillation unit. The distillation unit also includes at least one sieve tray having a plurality of perforations to enable passage for the vapour to pass therethrough. and a set of spray nozzles configured to spray a first cleaning mixture over the at least one sieve tray to prevent clogging of high silica & lignin sludge present in the biomass slurry and ethanol broth received by the at least one sieve tray.
[0027] Present invention introduces an innovative Distillation Column Internals Design that effectively addresses the challenges of separating entrainable silica particles and micro-lignin impurities in bioethanol production. The system employs an integrated approach combining several key components: a feed tray equipped with a vane-type feed inlet device in an inclined position to decelerate silica particles, causing them to fall into a drain sump, along with a strategically positioned donut tray above that creates a protective liquid curtain to prevent silica entrainment. Below the feed tray, a chimney tray with a packed bed provides additional refinement by further separating silica and lignin residues from the ethanol broth.
[0028] The design incorporates a spray nozzle system that injects an equimolar methanol-acetic acid cleaning mixture to break down stubborn lignin agglomerated clusters, while an automated sludge removal system ensures continuous extraction of silica, lignin and biomass residues, significantly reducing maintenance needs. An intelligent automated ratio controller monitors and adjusts the spray nozzle operation based on real-time ethanol purity and silica concentration data.
[0029] The design incorporates a spray nozzle system that injects a non-equimolar methanol-acetic acid cleaning mixture to break down stubborn lignin agglomerated clusters, while an automated sludge removal system ensures continuous extraction of silica, lignin and biomass residues, significantly reducing maintenance needs. An intelligent automated ratio controller monitors and adjusts the spray nozzle operation based on real-time ethanol purity and silica concentration data.
[0030] The distillation column is organized into several functional sections that work in concert to optimize performance. The rectification section maintains ethanol purity in compliance with IS15464:2004 standards while recovering valuable by-products. The specialized feed tray assembly, comprising both the vane-type inlet device and donut tray, serves as the primary silica removal stage. Downstream, the chimney tray with its packed bed provides secondary purification by capturing micro-lignin and residual silica particles. The sludge removal section utilizes Pall rings and chimney trays to efficiently collect and remove impurities, while the stripping section completes the process by separating ethanol from other components, thereby enhancing overall distillation efficiency. This comprehensive design represents a significant advancement in overcoming the persistent challenges posed by high-silica and lignin-rich feedstocks in bio-ethanol production. Above the reboiler, another sieve tray having a plurality of perforations to enable passage for the vapour to pass therethrough, and a set of spray nozzles configured to spray a first cleaning mixture over the at least one sieve tray to prevent clogging of lignin sludge present in the biomass slurry and ethanol broth received by the at least one sieve tray.
[0031] According to an embodiment, the number of each type of tray may vary according to hight of the column and the complexity of the biomass used. The number of each type of tray will increase with increase in high silica residue and lignin content to optimise the removal of the these contents from the distillation column.
[0032] According to an embodiment, the trays are constructed from SS-316 stainless steel to withstand corrosive and abrasive conditions caused by C-5 and C-6 sugars.
[0033] According to an embodiment, the spray nozzle system comprises 1 to 20 spray nozzles per sieve tray in particular 4 to 12 spray nozzles per sieve tray.
[0034] According to an embodiment, the the distillation column comprises a stripping section for separating ethanol from undesired components.
[0035] According to an embodiment, the spray nozzle system is configured to operate in co-current, counter-current, and cross-flow directions to dislodge and wash accumulated lignin from the sieve trays.
[0036] According to an embodiment, the automated ratio controller is configured to activate the spray nozzle system at intervals of 5 to 25 minutes particularly 10 to 15 minutes.
[0037] According to an embodiment, a rectification section is provided for maintaining ethanol purity in compliance with IS15464:2004 standards.
[0038] According to an embodiment, the distillation further comprises a drain outlet pipe positioned before the outlet downcomer, the drain outlet pipe configured to remove silica-lignin-laden slurry from the distillation column.
[0039] According to an embodiment, the drain outlet pipe is controlled by an actuated valve synchronized with the spray nozzle system.
[0040] According to an embodiment, the packed bed in the risers tray comprises random packing to capture suspended lignin and prevent entrainment into vapor streams.
[0041] According to an embodiment, the set of spray nozzles may be timer-controlled to dispense the first cleaning mixture over the at least one sieve tray in pre-defined time intervals.
[0042] According to an embodiment, the second set of spray nozzles may be timer-controlled to dispense the second cleaning mixture over the at least one feed tray in pre-defined time intervals.
[0043] According to an embodiment, the distillation unit may include a controller configured to monitor clogging of the lignin sludge received by any of the at least one sieve tray and the at least one feed tray. The controller may also be configured to control actuation of the first set of spray nozzles and the second set of spray nozzles based on pre-determined washing cycles, and one or more parameters pertaining to purity of the ethanol to be produced.
[0044] According to an embodiment, the first cleaning mixture may include equimolar mixture of acetic acid and methanol. According to another embodiment, the second cleaning mixture may include equimolar mixture of acetic acid and methanol.
[0045] According to an embodiment, the apparatus may include a ratio controller configured to control the equimolar mixture of methanol and acetic acid in a ratio of about 3% to 6% by volume.
[0046] According to an embodiment, the biomass slurry and ethanol broth may contain about 15-25% weight/weight (w/w) lignin sludge. According to another embodiment, the biomass slurry and ethanol broth may contain about 15% to 20% w/w lignin sludge.
[0047] The vane-type feed inlet device represents a critical innovation for capturing entrained silica particles before they interfere in the mass transfer process of upcoming vapors and radially flowing ethanol broth across sieve trays for desired ethanol distillation. Its design features an inclined feed inlet setup where strategically positioned vanes cause silica particles to lose momentum upon impact, directing them to fall back into a dedicated drain sump at the corner. This mechanism is complemented by a donut tray positioned above the feed tray, which generates a continuous liquid curtain that effectively prevents silica entrainment while enhancing phase separation efficiency. The drain sump serves as a collection point for separated silica particles, ensuring they are removed from the system before they can clog downstream components.
[0048] Further purification is achieved through a specialized chimney tray with an integrated packed bed system, which employs two distinct separation mechanisms. The packed bed utilizes random packing material to efficiently capture suspended lignin and silica particles, preventing their entrainment into vapor streams.
[0049] Positioned below the feed tray, the chimney tray collects silica and biomass deposits before the liquid progresses to the stripping section, maintaining process integrity.
[0050] The system also incorporates a spray nozzle that injects a methanol-acetic acid mixture to break down stubborn lignin agglomorates & deposits, making impurities easier to remove. This is paired with an automated sludge collection system that efficiently directs captured silica and biomass residues to a slurry sump for controlled disposal, ensuring uninterrupted operation and reduced maintenance requirements. Together, these components create a comprehensive solution for handling high-silica and lignin-rich feedstocks in bioethanol distillation.
[0051] According to an embodiment, the at least one sieve tray and the at least one feed tray may be arranged in a staggered manner relative to one another along a height of the distillation unit.
[0052] According to an embodiment, the distillation unit may include a feed entry nozzle configured to supply the biomass slurry and ethanol broth to any of the at least one sieve tray and the at least one feed tray at a pre-defined rate.
[0053] According to an embodiment, the distillation unit may include one or more settling tanks configured to receive the lignin sludge collected in the sump of the at least one feed tray.
[0054] According to an embodiment, the distillation unit may include a centrifuge configured to separate residual sludge from the lignin sludge received by the one or more settling tanks. A liquid output from the centrifuge may be supplied to the heat exchanger to generate the vapour.
[0055] According to an embodiment, the at least one feed tray may include a drain outlet pipe positioned at the sump to facilitate removal of the collected lignin sludge. The drain outlet pipe may be controlled by a valve synchronized with the second set of spray nozzles to optimize transfer of the collected lignin sludge to the one or more settling tanks.
[0056] According to an embodiment, the distillation unit may include an outlet nozzle configured to extract purified ethanol vapors from the distillation tower and further sending it to condenser & lastly to ethanol storage tanks.
[0057] According to an embodiment, the plurality of pall rings may be arranged on the at least one feed tray in a random packing arrangement to facilitate collection of the lignin sludge into the sump.
[0058] According to an embodiment, the at least one sieve tray may include a first weir to enable supply of the biomass slurry and ethanol broth in a downstream direction only when the biomass slurry and ethanol broth overflows through the first weir.
[0059] According to an embodiment, the at least one feed tray may include a second weir to allow supply of the biomass slurry and ethanol broth in the downstream direction only when the biomass slurry and ethanol broth overflows through the second weir.
[0060] According to another aspect of the present disclosure, a process for producing ethanol with a biomass slurry and ethanol broth having silic and moderate lignin content is disclosed. The process includes receiving, by a feed entry nozzle of a distillation unit, the biomass slurry and ethanol broth at a pre-defined rate. The process includes boiling, by a heat exchanger, a liquid at a bottom of the distillation unit to generate vapour traversing in a vertically upward direction through sieves of different trays filled with a pool of downward flowing ethanol broth (flowing radially across each tray) within the distillation unit, and supplying the biomass slurry and ethanol broth to at least one sieve tray having a plurality of perforations to enable passage for the vapour to pass therethrough. The purification process begins as the ethanol broth enters the vane-type feed inlet device, where strategically designed vanes cause silica particles to lose momentum and settle into the drain sump. Simultaneously, a protective liquid curtain generated by the donut tray positioned above effectively prevents any silica entrainment into the vapor phase.
[0061] The partially purified liquid then flows through the feed tray, which evenly distributes it into the chimney tray containing a packed bed system - here, residual lignin and any remaining silica particles undergo further separation. The now-cleaned liquid progresses to the stripping section where final purification occurs, ensuring high-purity ethanol output. Throughout this process, all trapped residues are automatically removed via the sludge removal system, effectively preventing fouling and maintaining continuous operation. This integrated sequence ensures efficient separation of impurities while optimizing ethanol recovery.
[0062] The process further includes regulating, by a controller, actuation of a first set of spray nozzles to control dispensing of a first cleaning mixture over the at least one sieve tray to prevent clogging of the biomass slurry and ethanol broth received by the at least one sieve tray, and actuation of a second set of spray nozzles to control dispensing of a second cleaning mixture over the at least one feed tray to enable collection of the lignin sludge into a sump of the at least one feed tray. An equimolar mixture of methanol and acetic acid is injected through the spray nozzle system to break down lignin nucleation sites and prevent agglomeration.
[0063] According to an embodiment, the step of regulating may include controlling actuation of the first set of spray nozzles and the second set of spray nozzles based on pre-determined washing cycles. The activation of the spray nozzle system is adjusted based on ethanol purity and feed composition using an automated ratio controller.
[0064] The Distillation Column Internals Design according to present invention effectively addresses the challenges of separating entrainable silica particles and micro-lignin impurities in bio-ethanol production. The system employs an integrated approach combining several key components: a feed tray equipped with a vane-type feed inlet device in an inclined position to decelerate silica particles, causing them to fall into a drain sump, along with a strategically positioned donut tray above that creates a protective liquid curtain to prevent silica entrainment. Below the feed tray, a chimney tray with a packed bed provides additional refinement by further separating silica and lignin residues from the ethanol broth.
[0065] The design incorporates a spray nozzle system that injects an equimolar methanol-acetic acid mixture to break down stubborn lignin agglomarates & clusters, while an automated sludge removal system ensures continuous extraction of silica and biomass residues, significantly reducing maintenance needs.
[0066] According to an embodiment, the equimolar mixture of methanol and acetic acid injected by the spray nozzle system comprises 3% to 6% methanol and 3% to 6% acetic acid by volume.
[0067] According to an embodiment, the intelligent automated ratio controller monitors and adjusts the spray nozzle operation based on real-time ethanol purity and silica concentration data.
[0068] According to an embodiment, the lignin-laden slurry removed by the automated sludge removal system is settled in a settling tank for 15 minutes to 4 hours before being sent to a centrifuge for further separation.
[0069] According to an embodiment, the clarified liquid from the centrifuge is recycled back to the reboiler pool liquid for reuse in the spray nozzle system.
[0070] According to an embodiment, the feed tray with downward V-notches is designed to handle a feed composition comprising 21% to 25% lignin by weight.
[0071] According to an embodiment, the process comprises separating ethanol from undesired components in a stripping section.
[0072] According to an embodiment, the stripping section operates at a temperature range of 78°C to 85°C to separate ethanol from water and other impurities.
[0073] According to an embodiment, the process comprises maintaining ethanol purity in a rectification section to achieve 95.5 mole% ethanol in compliance with IS15464:2004 standards.
[0074] According to an embodiment, the rectification section operates at a temperature range of 78°C to 82°C to maintain ethanol purity at 95.5 mole%.
[0075] According to an embodiment, the biomass slurry and ethanol broth may contain at least 15-25% w/w lignin sludge. According to another embodiment, the biomass slurry and ethanol broth may contain at least 15-20% w/w lignin sludge. According to another embodiment, the biomass slurry and ethanol broth may contain filamentious residues.
[0076] According to an embodiment, the process may include supplying the lignin sludge collected in the sump to one or more settling tanks, and separating, by a centrifuge of the distillation unit, residual sludge from the lignin sludge received by the one or more settling tanks. The process may further include supplying a liquid output from the centrifuge to the heat exchanger to generate the vapour.
[0077] According to an embodiment, the process may include extracting, by an outlet nozzle of the distillation unit, purified ethanol from the biomass slurry and ethanol broth.
[0078] According to an embodiment, the process may also include monitoring, by a controller, clogging of the lignin sludge received by any of the at least one sieve tray and the at least one feed tray. The process may further include controlling, by the controller, actuation of the first set of spray nozzles and the second set of spray nozzles based on pre-determined washing cycles and one or more parameters pertaining to purity of the ethanol to be produced.
[0079] According to an embodiment, the process may include regulating, by a first weir of the at least one sieve tray, flow of the biomass slurry and ethanol broth such that the biomass slurry and ethanol broth is supplied in a downstream direction only when the biomass slurry and ethanol broth overflows through the first weir. The process may further include regulating, by a second weir of the at least one feed tray, flow of the biomass slurry and ethanol broth such that the biomass slurry and ethanol broth is supplied in the downstream direction only when the biomass slurry and ethanol broth overflows through the second weir.
[0080] Various objects, features, aspects and advantages of the inventive subject matter will become more apparent from the following detailed description of preferred embodiments, along with the accompanying drawing figures in which like numerals represent like components.

BRIEF DESCRIPTION OF THE DRAWINGS
[0081] The accompanying drawings are included to provide a further understanding of the present disclosure, and are incorporated in and constitute a part of this specification. The drawings illustrate exemplary embodiments of the present disclosure and, together with the description, serve to explain the principles of the present disclosure.
[0082] FIG. 1 shows detailed distillation unit with distillation column according to the present invention.
[0083] FIG. 2 shows enlarged view of the distillation column showing the specialized feed trays according to present invention.
[0084] FIG. 3 shows enlarged view of the sieve tray with spary nozzles according to an exemplary embodiment of the present invention.
[0085] FIG. 4 shows enlarged view of the vane-type feed inlet device with liquid curtain and donut tray above feed tray according to an exemplary embodiment of the present invention.
[0086] FIG. 5 shows the enlarged view highlighting the specialized chimney Pall rings and risers;
[0087] FIG. 6 shows the Feed Tray with modified wiers according to an exemplary embodiment of the present invention;
[0088] FIG. 7 shows a flow chart depicting the process according to an embodiment of the present invention;

DETAILED DESCRIPTION
[0089] The following is a detailed description of embodiments of the disclosure depicted in the accompanying drawings. The embodiments are in such details as to clearly communicate the disclosure. However, the amount of detail offered is not intended to limit the anticipated variations of embodiments; on the contrary, the intention is to cover all modifications, equivalents, and alternatives falling within the scope of the present disclosures as defined by the appended claims.
[0090] The present invention provides a solution to a spectrum of engineering challenges in distillation columns/towers used for bio-ethanol distillation, with feedstock having silica and moderate lignin content. In addition to ethanol, fusel oil, and Technical Alcohol are produced as side cuts in the distillation column. The quality of the ethanol produced meets the Indian specifications (IS 15464:2004) for anhydrous ethanol for use in automotive fuel, with the desired ethanol content of 99.50% by volume. Ethanol and water form an azeotropic mixture at an ethanol mole percentage of approximately 91% (~96% by volume), preventing further purification by distillation. Molecular membranes are used to achieve the desired high-purity ethanol for blending. The process of ethanol production generally involves pre-treatment of biomass followed by tailored enzymatic hydrolysis of ligno-cellulosic biomass to fermentable sugars (C-5 and C-6 sugars). These sugars are fermented by common yeasts to produce ethanol. The ethanol broth is finally distilled using the distillation column, which contains micro-lignin produced during the steam explosion of the biomass pre-treatment step, dead yeast, enzymatic biomass, water, unutilized nutrients, and unconverted cellulose and hemicellulose. According to the Petroleum Planning & Analysis Cell (PPAC) market economics, with 20% blending of gasoline, 11,178 million liters of ethanol are required in the country. Therefore, the demand for bio-ethanol plants will increase significantly, and the need for novel distillation setups will also rise.
[0091] For brevity, due to the presence of high silica & micro-lignin in the ethanol broth, the valves and sieve trays of the distillation column are prone to frequent clogging, requiring a quick and efficient cleaning cycle for each tray. This cleaning cycle is a function of the biomass used, although the process remains feedstock-agnostic. The lignin percentage of the biomass affects the cleaning cycle time of the column. The present invention of the novel distillation tower encompasses robust bio-ethanol distillation capture from Rice Husk-Stalk Feed, and its use in situ in oil and gas refineries coupled with bio-refineries. This present invention provides an innovative solution for distillation of feedstock having high silica and moderate lignin content for the oil and gas industry, focusing on environmental footprint reduction across global communities, with the holistic goal of addressing the merits and challenges of three-phase distillation in bio-ethanol plants. In response to these challenges, the present invention introduces an apparatus and process for efficiently managing ethanol broth with a lignin-laden stillage.
[0092] Embodiments described herein relate to an apparatus and process for efficiently processing biomass slurries and ethanol broths with high silicaresidues and high lignin content to produce high ethanol yields. This results in a cost-effective, environmentally sustainable ethanol production process with reduced operational costs, energy consumption, and toxic by-products. The apparatus is adaptable to various biomass feedstocks, making it scalable for large-scale commercial bioethanol production, while contributing to the sustainability of biofuels as a renewable energy source.
[0093] FIG. 1 illustrates an exemplary schematic representation of an apparatus 100 for producing ethanol with a biomass slurry and ethanol broth having high silica residues and high lignin content. The apparatus 100 includes a distillation unit (also referred to as “distillation tower” herein) 102 configured to receive and process the biomass slurry and ethanol broth to reduce lignin content thereof. The biomass slurry and ethanol broth may include High-Silica-Residues & Moderate-Lignin laden Rice Husk-Stalk Feed feedstock which contain about 15-25% weight/weight (w/w) lignin sludge and silica residues.
[0094] The distillation tower 102 includes a feed entry nozzle 104 that receives the biomass slurry and ethanol broth containing the silica lignin-laden ethanol broth, and supplies the biomass slurry and ethanol broth within the distillation tower 102 for processing. The distillation tower 102 includes a heat exchanger 106, such as a reboiler, configured to boil a liquid at a bottom of the distillation tower 102 to generate vapour traversing in a vertically upward direction within the distillation tower 102. The distillation tower 102 also includes one or more sieve trays 108-1, 108-2, 108-3, 108-4, … 108-N (also referred to as “sieve tray 108” herein) arranged along a height of the distillation tower 102 as shown in detailed view of Fig. 3. The sieve tray 108 includes a plurality of perforations 110 to enable passage for the vapour generated by the heat exchanger 106 to pass therethrough, and a first set of spray nozzles 112 configured to spray a first cleaning mixture over the sieve tray 108 to prevent clogging of lignin sludge present in the biomass slurry and ethanol broth received by the sieve tray 108. The first set of spray nozzles 112 may be timer-controlled to dispense the first cleaning mixture over the at least one sieve tray in pre-defined time intervals of 5 to 25 minutes, for example. Each sieve tray 108 may include 1 to 20 spray nozzles 112 to direct the first cleaning mixture in an opposite direction to fractionation flow of the biomass slurry and ethanol broth over the sieve tray 108. The first cleaning mixture may include equimolar mixture of acetic acid and methanol. The sieve tray 108 may include a first weir to allow supply of the biomass slurry and ethanol broth in a downstream direction only when the biomass slurry and ethanol broth overflows through the first weir.
[0095] The distillation tower 102 also includes one or more feed trays 114 arranged along the height of the distillation tower 102. At least one feed tray 114 may be positioned downstream of at least one sieve tray 108 such that the biomass slurry and ethanol broth flows over the feed tray 114 after passing through the sieve tray 108 located upstream of the feed tray 114. The feed trays 114 may be formed of SS-316 (Stainless Steel) to efficiently facilitate processing of corrosive and abrasive C-5 sugar (xylan) and C-6 sugar (glucose) laden biomass slurry and ethanol broth.
[0096] The distillation tower 102, as depicted in FIG. 1, is designed with several key features to facilitate efficient distillation and ethanol recovery. A liquid inlet nozzle 216 is configured to introduce the liquid feed into the distillation tower 102, directing it to the reboiler 106. The reboiler 106 heats the liquid supplied into the distillation tower 102 through the liquid inlet nozzle 216, to generate the vapour that ascends vertically within the distillation tower 102. This vapour is crucial for the distillation/separation process for production of high yield of ethanol from the biomass slurry and ethanol broth. As the vapour rises through the distillation tower 102, it allows for the separation of various components of the biomass slurry and ethanol broth based on their boiling points to facilitate production of ethanol with improved purity.
[0097] The distillation tower 102 may include a vapour outlet nozzle 118, which is designed to drain the vapour generated by the reboiler 106. This vapour is directed out of the distillation tower 102 and into the surrounding ambient environment, where it can undergo further processing, such as condensation or phase separation. Additionally, the distillation tower 102 may be equipped with a vapour inlet nozzle that facilitates entry of the vapour generated by the reboiler 106 into the distillation tower 102, helping maintain the necessary vapour-liquid equilibrium for effective separation. A liquid outlet nozzle positioned at the bottom of the distillation tower 102 allows the liquid from a liquid pool located at the bottom of the distillation tower 102 to flow into the reboiler 106, ensuring the liquid is constantly circulated and heated. This circulation is essential for the continued operation of the distillation process, as it ensures that the liquid is heated appropriately to produce further vapour for separation of ethanol from the biomass slurry and ethanol broth. The High Liquid Level (HLL) for the reboiler liquid pool at the bottom/base of the distillation tower 102 may be calibrated 10% higher than conventional distillation columns.
[0098] The distillation tower 102 may include an outlet nozzle 120, which enables extraction of the purified ethanol from the biomass slurry and ethanol broth. The outlet nozzle 120 serves as the key point for the collection of the ethanol product that has been separated during the distillation process. The distillation tower 102 is also configured with a methanol tank 122 and an acetic acid tank 124, both of which store by-products generated during the cleaning cycles for the sieve trays 108 and the feed trays 114. These by-products are obtained from side streams that flush cleaning mixtures over the sieve trays 108 and the feed trays 114, respectively. The methanol tank 122 stores methanol, and the acetic acid tank 124 stores acetic acid, both of which are recovered and stored for potential reuse or disposal. Each of these tanks 122 and 124 is equipped with a metering pump, which plays a critical role in ensuring that the correct amount of methanol and acetic acid is accurately delivered to the spray nozzles of the sieve trays 108 and the feed trays 114. This precise dosing is essential to maintain optimal cleaning cycles for the sieve trays 108 and feed trays 114, ensuring that any contaminants or residues are removed effectively. This cleaning process is crucial for maintaining consistent ethanol quality, as any build-up on the sieve trays 108 and the feed trays 114 could hinder proper separation and reduce product purity. In an exemplary embodiment, the metering pumps connected to the methanol and acetic acid tanks 122, 124 may be configured to pump an equimolar mixture of about 3% to 6% (by volume) methanol and acetic acid. The ratio of these two chemicals is carefully controlled by a ratio controller 126, which ensures that the cleaning mixtures used for cleaning the sieve trays 108 and the feed trays 114 are in the correct proportion for effective tray maintenance.
[0099] The distillation tower 102 may include a condenser 128, which plays a vital role in cooling and condensing the vapour exiting the vapour outlet nozzle 118. The condenser 128 helps convert the vapour back into a liquid phase, which can then be separated and collected for further processing. In conjunction with the condenser, a 3-Phase separator/reflux drum 130 is installed to efficiently separate and recover the different phases of the vapour, which includes condensed liquid, residual gases, and any non-condensable components. This phase separation is important for optimizing the distillation process and ensuring that the desired products are recovered efficiently. To ensure the quality and composition of the vapour stream before it is condensed, a product analyzer 128-1 is installed upstream of the condenser 128. The product analyzer 128-1 continuously monitors the composition of the vapour exiting the vapour outlet nozzle 118, providing real-time data on the quality of the vapour. This information is crucial for process control, as it ensures that the vapour meets the necessary specifications for condensation and further processing.
[00100] For handling heavier or more viscous liquids that may accumulate at the bottom of the distillation tower 102, a heavy product pump 132 is incorporated. The heavy product pump 132 is responsible for transferring these liquid products, which may be high in temperature or viscosity, from the bottom of the distillation tower 102 to downstream processing units or storage tanks. This ensures that the distillation process operates smoothly, even with challenging product characteristics. Additionally, a reflux pump 134 is employed to circulate a portion of the condensed vapour back into the distillation tower 102. The reflux pump 134 helps improve separation efficiency by sending the condensed liquid back to the distillation tower 102, where it can interact with the rising vapour. This refluxing action aids in refining the separation process, resulting in higher ethanol purity and overall performance of the distillation tower 102.
[00101] Referring now to FIG. 2, which shows an enlarged view of the distillation column as shown in Fig. 1 the column include below the sieve tray (not shown in Fig. 2) a feed tray 115 with both a vane-type feed inlet device and a donut tray 114 above. The feed tray 115 facilitates controlled liquid distribution for phase separation. The Vane-Type feed inlet device at an inclined position ensures silica particles lose momentum upon impact and fall into the drain sump. The donut tray 114 that is placed above the feed tray 115 creates a liquid curtain covering the vane-type inlet device, preventing silica entrainment.
[00102] Downstream the feed tray 114, a chimney tray 116 with risers 208 and pall rings 202 is provided. The pall rings 202 provided trap the high lignin content present in the feedstock. The risers 208 provided on the tray allow the rising vapours to rise through the feed tray without any hindrance. The lignin which is trapped by the pall rings 202 is washed out using the second set of spray nozzels provided on the chimney tray 116.
[00103] The chimney tray 116 also includes a third set of spray nozzles (not shown) configured to spray a cleaning mixture over the chimney tray 116 to prevent clogging of the lignin sludge present in the biomass slurry and ethanol broth received by the chimney tray 116. The pall rings 202 ensure that the lignin sludge present in the biomass slurry and ethanol broth is stagnated and segregated from the biomass slurry and ethanol broth. Subsequently, the set of spray nozzles may dispense the cleaning mixture over the chimney tray 116 to enable collection of the stagnated lignin sludge into a sump 206 of the chimney tray 116. The chimney tray 116 may also include a plurality of risers 208 that allow the vapour generated by the heat exchanger 106 to escape therethrough in the vertically upward direction, and facilitate liquid-gas mass transfer & interaction between the biomass slurry and ethanol broth and the vapour. The set of spray nozzles may be timer-controlled to dispense the cleaning mixture over the chimney tray 116 in pre-defined time intervals of 5 to 25 minutes, for example. In an exemplary embodiment, the chimney tray 116 may include 1 to 20 spray nozzles to direct the second cleaning mixture in the opposite direction to the fractionation flow of the biomass slurry and ethanol broth over the chimney tray 116. The cleaning mixture may contain an equimolar mixture of acetic acid and methanol. Chimney Tray with Pall ring Packed Bed (Below Feed Tray): Further refines silica and lignin separation to ensure cleaner ethanol broth.
[00104] The pall rings 202 may be arranged over the chimney tray 116 in a staggered/random manner such that the lignin sludge contained within the biomass slurry and ethanol broth is segregated when the biomass slurry and ethanol broth passes over the chimney tray 116, and gets collected within a sump 206 of the chimney tray 116.
[00105] In an exemplary embodiment, the third type of feed tray 117 with only modified wiers (203) for fiber separation and lignin accumulation. Wiers (203) on plates help in enhanced lignin and silica removal.
[00106] The sets of spray nozzles may be configured to flush the cleaning mixtures over the corresponding sieve tray 108 or the trays 116 and 117 in any of three primary directions, including co-current, counter-current, and cross-flow directions, each serving a unique function in the process of removing lignin agglomerates or nucleation sites on the sieve tray 108 or the tray 115, 116 and 117 within the distillation tower 102.
[00107] The apparatus 100 may include the ratio controller 126 configured to control the equimolar mixture of methanol and acetic acid in a ratio of about 3% to 6% by volume, for each of the first cleaning mixture and the second cleaning mixture. The distillation tower 102 may include a controller configured to monitor clogging of the lignin sludge received by any of the sieve trays 108 and the feed trays 114. The controller may also be configured to control actuation of the set of spray nozzles based on pre-determined washing cycles, and one or more parameters pertaining to purity of the ethanol to be produced. The controller may also be configured to actuate the sets of spray nozzles in response to ethanol specification disturbances caused by the clogging/choking of the sieve trays 108 and the feed trays 114.
[00108] In an exemplary embodiment, the controller is configured to manage the sets of spray nozzles to eject the equimolar mixture of acetic acid and methanol. This equimolar mixture, when mixed with the pool liquid pool of the reboiler 106, plays a pivotal role in breaking down the nucleation sites of agglomerating lignin. Typically, C-5 sugar (xylan) and C-6 sugar (glucose) provide a crucial substrate for agglomeration and nucleation sites on suspended micro-lignin fibers, subsequently converting them into bulky lignin lumps near the sieves of the column tray. The 3%-6% (by volume) equimolar mixture of acetic acid and methanol helps prevent these nucleation sites from forming in the early stages of the distillation process.
[00109] The controller may be implemented using various hardware configurations or a combination of software and hardware features. For instance, the controller may incorporate microcontrollers, switches, relays, gates, and specialized hardware features like application-specific integrated circuits (ASICs), electrically erasable programmable read-only memories (EEPROMs), or field-programmable gate arrays (FPGAs). In some cases, memory components like non-volatile random access memory (RAM) or read-only memory (ROM) may also form part of the controller. In another embodiment, the controller may be entirely software-based, operating either as part of an operating system or as an application running on one. The controller may be connected to the first and second sets of spray nozzles 112, 204 either wirelessly or in a wired manner.
[00110] The sieve trays 108 and the feed trays 114, 115, 116 and 117 may be arranged in a staggered manner relative to one another along the height of the distillation tower 102, such that the biomass slurry and ethanol broth introduced within the distillation tower 102 by the feed entry nozzle 104 passes through each of the sieve trays 108 and the feed trays 114 to enable effective segregation of the lignin sludge and silica residues from the biomass slurry and ethanol broth. In an exemplary embodiment, the feed entry nozzle 104 may be positioned such that the biomass slurry and ethanol broth introduced within the distillation tower 102 is supplied over any or a combination of the sieve trays 108 and the feed trays 114, 115, 116 and 117 in a sequential manner.
[00111] The distillation tower 102 may include one or more settling tanks including a primary settling tank 136 and a secondary settling tank 138 configured to receive the lignin sludge collected in the sumps 206 of each of the trays. The secondary settling tank 138 may be an alternate outlet route for collection of the first and second cleaning mixtures and the lignin sludge received from the sumps 206 of the feed trays 114. The distillation tower 102 may also include a centrifuge 140 configured to separate residual sludge from the lignin sludge received by the primary and secondary settling tanks 136, 138. A settling tank pump 142 may be configured to pump the collected fluid from the primary and secondary settling tanks 136, 138 to the centrifuge 140 to separate the residual lignin sludge from the collected fluid. A liquid output from the centrifuge 140 may be supplied to the reboiler 106, through a pump, to generate the vapour that traverses in the vertically upward direction within the distillation tower 102. The centrifuge 102 may include a drain outlet 140-1 to enable drainage of the liquid sludge.
[00112] Each of the feed trays 114, 115, 116 and 117 may include a drain outlet pipe 210, as shown in FIG. 2, positioned at the sump 206 to facilitate removal of the collected lignin/Silica sludge. The drain outlet pipe 210 may be controlled by a valve synchronized with the second set of spray nozzles 204 to optimize transfer of the collected lignin sludge to any of the primary and secondary settling tanks 136, 138. Each of the feed trays 114, 115, 116 and 117 may include a second weir 212 to allow supply of the biomass slurry and ethanol broth in the downstream direction only when the biomass slurry and ethanol broth overflows through the second weir 212, while the lignin sludge gets collected in the sump 206 of the feed trays 114, 115, 116 and 117.
[00113] In an exemplary embodiment, the drain outlet pipe 210 may be controlled by an actuated valve connected to the second set of spray nozzles 204. The actuation of this valve is coordinated with a timer and ethanol specification controller, operating in tandem with the ratio controller 126. As a result, whenever the set of spray nozzles is activated, the valve is simultaneously triggered to open the drain outlet pipe 210. This allows the washed liquid with high silicaresidue and lignin sludge to flow into the settling tanks 136 and 138. In a further embodiment, a portion of the biomass slurry and ethanol broth, which is laden with lignin sludge and high silicaresidue, is directed through an outlet downcomer to the bottom-most sieve tray 108. From there, the process continues in a sequential manner, ensuring that most of the lignin stillage follows its intended path toward the settling tanks 136 and 138. This controlled flow is essential to maintain the efficiency of the separation process and to ensure that the by-products are properly collected and separated for further processing or disposal.
[00114] The drain outlet pipe 210 may be controlled by an actuated valve connected with the second set of spray nozzles 204, such that actuation of the valve is dual-actuated with timer-controlled and ethanol specification-controlled in tandem with the ratio controller 126. Therefore, whenever the second set of spray nozzles 204 are actuated, the valve is actuated to open the drain outlet pipe 210 and enable the washed liquid and lignin sludge to flow to the settling tanks 136, 138. In an exemplary embodiment, a percentage of the biomass slurry and ethanol broth laden with lignin sludge escapes through an outlet downcomer to the bottom-most sieve tray 108, and the process continues in a sequential manner with most of the lignin stillage finding its route to the settling tanks 136, 138.
[00115] In an exemplary embodiment, the lignin-laden biomass slurry and ethanol broth that escapes from the last tray 108/117 reaches the liquid pool at the bottom of the distillation tower 102 and mixes with the clean liquid coming from the centrifuge 140. In the distillation tower 102, there is an outlet nozzle for the liquid to flow to the reboiler 106 from the liquid pool. To remove lignin slipping into the reboiler liquid pool, an additional sump may be provided at the base of the outlet nozzle (for the reboiler liquid flow). The sump allows for additional settling time, and there may be provided an additional slurry nozzle at the base of the distillation tower 102 to transport the slurry to the settling tanks 136, 138. This slurry may be mixed with the slurry coming from individual drain outlet pipes 210 provided on each feed tray 114, with the drain outlet pipe valve actuated by in synchronization with actuation of the spray nozzles 112, 204. Thus, all lignin content, undigested biomass fibers, untrapped silt and mud, unconverted cellulose, unconverted hemicellulose, unconverted arabinan, unconverted extractives, unconverted proteins, biomass ash, urea, DAP, molasses, inorganic mineral salts (neutralization products), inorganic antifoam agent residues, dead enzymatic mass, and dead yeast mass are 100% removed from the distillation tower 102 without compromising the ethanol specification quality and ensuring uninterrupted, trouble-free operation of the trays 108, 117, free from lignin lumps and nucleation-assisted lignin agglomerates.
[00116] Fig. 4 shows a detailed view of the a feed tray 114 equipped with a vane-type feed inlet device 211 in an inclined position to decelerate silica particles, causing them to fall into a drain sump, along with a strategically positioned donut tray 210 above that creates a protective liquid curtain to prevent silica entrainment.
[00117] Fig. 5 shows a detailed view of the chimney tray 116 with a packed bed that provides additional refinement by further separating silica and lignin residues from the ethanol broth. The chimney tray 116 includes risers 208 and pall rings 202. The pall rings 202 trap the high lignin content present in the feedstock. The risers 208 provided on the tray allow the rising vapours to rise through the feed tray without any hindrance. The lignin which is trapped by the pall rings 202 is washed out using the second set of spray nozzels provided on the chimney tray 116. The design incorporates a spray nozzle system (not shown) that injects an equimolar methanol-acetic acid mixture to break down stubborn lignin clusters, while an automated sludge removal system ensures continuous extraction of silica and biomass residues, significantly reducing maintenance needs. An intelligent automated ratio controller monitors and adjusts the spray nozzle operation based on real-time ethanol purity and silica concentration data.
[00118] Fig. 6 shows a detailed view of the modified sieve tray 117 provided with the plurality of modified wiers, which further trap the silica and lignin making the ethanol broth more clear. on the tray may be varied according to requirement of the column based on the composition of the feed. The modified sieve tray 117 incorporates a spray nozzle system (not shown) that injects an equimolar methanol-acetic acid mixture to break down stubborn lignin agglomarates & clusters, while an automated sludge removal system ensures continuous extraction of silica and biomass residues, significantly reducing maintenance needs.
[00119] FIG. 7 illustrates an exemplary flow chart representation of a process 700 for producing ethanol with a biomass slurry and ethanol broth having high silicaresidue and high lignin content. The process 700 is performed by the apparatus 100 depicted in FIG. 1. The biomass slurry and ethanol broth may contain at least 15-25% w/w lignin sludge with silica. In an embodiment, the biomass slurry and ethanol broth may contain at least 15-20% w/w lignin sludge with fibrous residues.
[00120] The process 700 includes a step 702 of receiving, by the feed entry nozzle 104 of the distillation tower 102, the biomass slurry and ethanol broth at a pre-defined rate. The biomass slurry and ethanol broth is supplied to the at least one sieve tray 108 having the perforations 110 to enable passage for the vapour to pass therethrough. The process 700 also includes, at step 704, supplying the biomass slurry and ethanol broth to at least one sieve tray (108) having a plurality of perforations (110) to enable passage for the vapour to pass therethrough. The process 700 further includes, at step 706, passing the ethanol broth through a feed tray 114 equipped with a vane-type feed inlet device 211 in an inclined position to decelerate silica particles, causing them to fall into a drain sump, along with a strategically positioned donut tray 210 above that creates a protective liquid curtain to prevent silica entrainment. At the step 708, the process includes directing the ethanol broth through a chimney tray 116 comprising a packed bed with pall rings (202) and risers (208) to further separate lignin and fibrous residues;
[00121] The process 700 also includes, at step 710, boiling, by the heat exchanger 106, a liquid at the bottom of the distillation tower 102 to generate vapour traversing in the vertically upward direction within the distillation tower 102. The pall rings 202 of the at least one chimney tray 116 positioned downstream of the at least one sieve tray 108, entrap and segregate lignin sludge from the biomass slurry and ethanol broth. At 712 process includes allowing, by the risers 208 of the at least one chimney tray 116, the vapour generated by the heat exchanger 106 to escape therethrough in the vertically upward direction.
[00122] The process 700 further includes a step 714 of regulating, by a controller of the apparatus 100, actuation of the first set of spray nozzles 112 to control dispensing of the first cleaning mixture over the sieve trays 108 to prevent clogging of the biomass slurry and ethanol broth received by the sieve trays 108, and actuation of the second set of spray nozzles 204 to control dispensing of the second cleaning mixture over the feed trays 114 to enable collection of the lignin sludge into the sumps 206 thereof. The step 712 of regulating may include controlling actuation of the first set of spray nozzles 112 and the second set of spray nozzles 204 based on pre-determined washing cycles. The process 700 may also include a step of monitoring, by the controller, clogging of the lignin sludge received by any of the sieve trays 108 and the feed trays 114. The process 700 may further include controlling, by the controller, actuation of the first set of spray nozzles 112 and the second set of spray nozzles 204 based on pre-determined washing cycles and one or more parameters pertaining to purity of the ethanol to be produced.
[00123] The process 700 may include a step 716 of injecting an equimolar mixture of methanol and acetic acid through a spray nozzle system to break down lignin nucleation sites and prevent agglomeration;
[00124] The process 700 may include a step of supplying the lignin sludge collected in the sumps 206 of the feed trays 114 to the settling tanks 136, 138 of the distillation tower 102. The process 700 may further include a step of separating, by the centrifuge 140 of the distillation tower 102, residual sludge from the lignin sludge received by the settling tanks 136, 138. The process 700 may also include supplying a liquid output from the centrifuge 140 to the heat exchanger 106 to facilitate generation of the vapour. The process 700 may include extracting, by the outlet nozzle 120 of the distillation tower 102, purified ethanol from the biomass slurry and ethanol broth.
[00125] The process 700 may include regulating, by the first weirs of the sieve trays 108, flow of the biomass slurry and ethanol broth such that the biomass slurry and ethanol broth is supplied in the downstream direction only when the biomass slurry and ethanol broth overflows through the first weirs. The process 700 may further include regulating, by the second weirs 212 of the feed trays 114, flow of the biomass slurry and ethanol broth such that the biomass slurry and ethanol broth is supplied in the downstream direction only when the biomass slurry and ethanol broth overflows through the second weirs 212.
[00126] In the process the equimolar mixture of methanol and acetic acid injected by the spray nozzle system comprises 3% to 6% methanol and 3% to 6% acetic acid by volume.
[00127] In the process 700, the automated ratio controller adjusts the spray nozzle system activation based on a feedback mechanism triggered by an increase in vapor velocity due to sieve tray clogging.
[00128] In the process 700, the lignin-laden slurry removed by the automated sludge removal system is settled in a settling tank for 15 minutes to 4 hours before being sent to a centrifuge for further separation.
[00129] In the process 700, the clarified liquid from the centrifuge is recycled back to the reboiler pool liquid for reuse in the spray nozzle system.
[00130] In the process 700, a vane-type feed inlet device in an inclined position to decelerate silica particles, causing them to fall into a drain sump, along with a strategically positioned donut tray above that creates a protective liquid curtain to prevent silica entrainment where the lignin is present in 15% to 15 % w/w.
[00131] In the process 700, the process comprises separating ethanol from undesired components in a stripping section.
[00132] In the process 700, the stripping section operates at a temperature range of 78°C to 85°C to separate ethanol from water and other impurities.
[00133] In the process 700, comprising maintaining ethanol purity in a rectification section to achieve 95.5 mole% ethanol in compliance with IS15464:2004 standards.
[00134] In the process 700, the rectification section operates at a temperature range of 78°C to 82°C to maintain ethanol purity at 95.5 mole%.
[00135] With the apparatus 100 and the process 700 of the present disclosure, the purity of the ethanol azeotrope (95.5 mole %) distilled from the distillation tower 102 can be achieved on a continuous process basis without any bottlenecks or intermittent troubleshooting of the distillation tower 102 due to the formation of C-5 sugar (xylan) and C-6 sugar (glucose) assisted nucleated lignin agglomerates and lumps. After the formation of the ethanol azeotrope (95.5 mole % ethanol) as a product from the distillation tower 102, the product stream may be routed to a dehydration column packed with molecular sieves. These molecular sieves help reduce the residual water content in the ethanol azeotropic mixture. Ethanol quality (99.5 mol %, at 15.6/15.6°C Min.) and the standard as per Indian specifications (IS 15464:2004) for anhydrous ethanol, suitable for use in automotive fuel, can be easily achieved as the final product from the outlet of the molecular sieves. The ethanol product may then be routed to a run-down storage tank for final loading into tankers via the gantry.
[00136] Thus, the apparatus 100 and the process 700 of the present disclosure enable the efficient processing of biomass slurries and ethanol broths with high silicaresidues and high lignin content to produce high yields of ethanol. By reducing lignin-related barriers, the process 700 enhances enzymatic hydrolysis and fermentation efficiency, leading to improved ethanol production. The apparatus 100 and the process 700 minimize the need for excessive energy input, harsh chemicals, and enzymes, thereby reducing environmental impact and operational costs compared to conventional ethanol production techniques. The apparatus 100 processes the biomass slurries and ethanol broths while optimizing the accessibility of cellulose and hemicellulose to enzymes, improving hydrolysis efficiency and reducing reaction times. The apparatus 100 also ensures the efficient conversion of fermentable sugars into ethanol with minimal by-product formation, contributing to higher yields and cleaner fermentation.
[00137] While the present invention has been described with reference to High Silica Residues and Moderate-Lignin Laden Rice Husk-Stalk Feed, it is to be understood that the disclosed distillation system and process are not limited to these specific feedstocks. Other feedstocks possessing comparable High Silica Residues and Moderate-Lignin content may also be effectively processed using the disclosed system and method. For example, slurries comprising combinations of high Silica Residues and Moderate-Lignin content materials—such as mixtures of rice husk, wheat straw, sugarcane bagasse, corn stover, and other lignocellulosic biomass—may be utilized for bioethanol production while achieving enhanced purity. The scope of the invention is therefore intended to encompass all such modifications, equivalents, and alternatives that fall within the spirit and scope of the appended claims.

ADVANTAGES OF THE PRESENT DISCLOSURE
[00138] The present disclosure provides an apparatus and a process for efficiently processing biomass slurries and ethanol broths with high silica residues and high lignin content, enabling high yields of ethanol. By reducing lignin-related barriers, the process enhances the efficiency of both enzymatic hydrolysis and fermentation, thereby improving ethanol production.
[00139] The present disclosure provides a process for producing ethanol from biomass slurries and ethanol broths without the need for excessive energy input or harsh chemicals. This reduces the environmental impact and lowers operational costs associated with conventional processes that rely on aggressive chemicals and energy-intensive processs.
[00140] The present disclosure provides an apparatus and process for the production of ethanol while reducing energy consumption, chemical use, and enzyme requirements. This makes the apparatus economically viable and competitive for large-scale commercial ethanol production.
[00141] The present disclosure provides a process that promotes environmentally sustainable bioethanol production by reducing the need for harsh chemicals, lowering energy consumption, and minimizing by-product generation. This contributes to the sustainability of biofuels as a renewable energy source, making the process eco-friendly.
[00142] The present disclosure provides an apparatus designed to be adaptable to a wide range of biomass feedstocks with silica and moderate lignin content. This flexibility allows the apparatus to process different types of biomass, making it scalable and versatile for various industrial applications and feedstock types.
[00143] The present disclosure provides an apparatus and process for producing ethanol that are easily scalable for large-scale bioethanol production, maintaining high efficiency and low operational costs. The scalability of the apparatus helps meet the increasing global demand for biofuels while maintaining efficient production processes.
[00144] The distillation system of the present invention offers several key advantages. The vane-type inlet device with an inclined setup ensures superior silica particle removal by effectively capturing entrainable silica, thereby preventing contamination. It enables the production of ethanol with enhanced purity, achieving 95.5 mole% ethanol in compliance with IS15464:2004 standards. The system supports continuous tower operation, significantly reducing clogging issues and minimizing shutdowns and maintenance requirements. Additionally, it features optimized energy utilization, lowering heat loss and energy consumption associated with cleaning. The process is cost-effective, as it facilitates the recovery of methanol and acetic acid, improving overall economic feasibility. An automated cleaning mechanism, managed by a ratio controller, ensures dynamic process adjustments without the need for manual intervention. The system also delivers environmental benefits, aligning with India’s Net Zero 2070 Goal and contributing to sustainable biofuel production. Lastly, its scalability makes it suitable for both small and large industrial bio-refinery setups, enhancing its adaptability across diverse production scales.
, Claims:1. A distillation unit for producing ethanol from a biomass slurry and ethanol broth having silica and moderate lignin content, the apparatus comprising:
- a distillation column configured to receive and process the biomass slurry and ethanol broth;
- a vane-type feed inlet device positioned in an inclined manner to decelerate and momentum loss for silica particles, causing them to fall into a drain sump;
- a donut tray positioned above the vane-type feed inlet device, configured to generate a protective liquid curtain to prevent silica entrainment;
- a chimney tray positioned downstream of the vane-type feed inlet device, the chimney tray comprising a packed bed with pall rings to trap residual lignin and silica particles;
- at least one sieve tray comprising a plurality of perforations to facilitate vapor passage and liquid-gas interaction and mass transfer thereof;
- a spray nozzle system configured to dispense a cleaning mixture of methanol and acetic acid over the sieve tray and chimney tray to prevent clogging and lignin accumulation;
- a heat exchanger positioned at a bottom of the distillation unit to boil a liquid and generate vapour traversing upwardly across the trays filled with radially flowing pool of liquid within the distillation unit;
- an automated sludge removal system configured to continuously extract micro-lignin and fibrous residues from the distillation column;
- an automated ratio controller configured to adjust the activation of the spray nozzle system based on ethanol purity and feed composition, wherein the spray nozzle system is configured to inject a cleaning mixture of methanol and acetic acid to break down lignin nucleation sites and prevent agglomeration.
2. The distillation unit as claimed in claim 1, wherein the chimney tray further comprises risers configured to allow the rising vapor to pass therethrough, facilitating improved vapor-liquid interaction.
3. The distillation unit as claimed in claim 1, wherein the pall rings in the packed bed of the chimney tray are arranged in a random packing configuration to entrap lignin and silica and there separation thereof.
4. The distillation unit as claimed in claim 1, wherein the sieve trays are constructed from SS-316 stainless steel to withstand corrosive and abrasive conditions caused by C-5 and C-6 sugars.
5. The distillation unit as claimed in claim 1, wherein the spray nozzle system is configured to operate in co-current, counter-current, or cross-flow directions to effectively wash away accumulated lignin deposits.
6. The distillation unit as claimed in claim 1, wherein the spray nozzle system comprises 4 to 12 spray nozzles per sieve tray, positioned to evenly distribute the cleaning mixture over the sieve tray surface.
7. The distillation unit as claimed in claim 1, wherein the automated ratio controller is configured to adjust the spray nozzle activation at intervals of 5 to 25 minutes, particularly between 10 to 15 minutes based on ethanol purity levels.
8. The distillation unit as claimed in claim 1, wherein the rectification section operates at a temperature range of 78°C to 82°C to maintain ethanol purity at 95.5 mole% ethanol.
9. The distillation unit as claimed in claim 1, wherein the distillation unit further comprises a stripping section configured to separate ethanol from undesired components at a temperature range of 78°C to 85°C.
10. The distillation unit as claimed in claim 1, wherein the drain outlet pipe positioned before the outlet downcomer is controlled by an actuated valve synchronized with the spray nozzle system for continuous sludge removal.
11. The distillation unit as claimed in claim 1, wherein the sump of the chimney tray is connected to at least one settling tank configured to receive and store silica-lignin-laden sludge for further separation.
12. The distillation unit as claimed in claim 1, wherein the settling tank is connected to a centrifuge, which separates residual sludge from the lignin sludge, and a liquid output is recycled to the heat exchanger.
13. The distillation unit as claimed in claim 1, wherein the liquid curtain formed by the donut tray is dynamically controlled to adjust the flow rate based on real-time silica concentration in the ethanol broth.
14. The distillation unit as claimed in claim 1, wherein the feed tray comprises upward pointing V-notches, that are arranged all across the sieve tray to break the momentum and provide nucleation site for lignin to form agglomarates at the base of these V-notches and process assisited by presence of C5 & C6 sugars for biomass slurry and ethanol broth compositions containing 21% to 25% lignin by weight.
15. A process for producing ethanol from a biomass slurry and ethanol broth having silica and moderate lignin content, the process comprising:
- receiving, by a feed entry nozzle, the biomass slurry and ethanol broth at a predefined rate;
- boiling, by a heat exchanger, a liquid at the bottom of a distillation unit to generate vapor that traverses in a vertically upward direction within the distillation unit;
- directing the ethanol broth through a vane-type feed inlet device positioned in an inclined manner to decelerate silica particles, causing them to fall into a drain sump;
- generating a protective liquid curtain, by a donut tray positioned above the feed inlet device, to prevent silica entrainment;
- passing the ethanol broth through a chimney tray comprising a packed bed with pall rings to separate lignin and silica residues from the ethanol broth;
- boiling a liquid at a bottom of the distillation unit to generate vapour traversing upwardly;
- regulating the spraying of the cleaning mixtures based on pre-determined washing cycles, ethanol purity parameters and feed composition using an automated ratio controller;
- injecting an equimolar mixture of methanol and acetic acid through a spray nozzle system to break down lignin nucleation sites and prevent agglomeration;
- continuously removing micro-lignin and fibrous residues through an automated sludge removal system from the sump via a drain outlet pipe;
- extracting purified ethanol from the distillation unit.
16. The process as claimed in claim 15, further comprising allowing, by risers in the chimney tray, the vapor generated by the heat exchanger to escape therethrough in a vertically upward direction.
17. The process as claimed in claim 15, wherein the pall rings in the chimney tray are arranged in a random packing manner to enhance silica and lignin separation efficiency.
18. The process as claimed in claim 15, wherein the sieve trays are formed of SS-316 stainless steel to withstand the corrosive nature of the biomass slurry and ethanol broth.
19. The process as claimed in claim 15, further comprising operating the spray nozzle system in co-current, counter-current, and cross-flow configurations to maximize lignin removal.
20. The process as claimed in claim 15, wherein the spray nozzle system dispenses the cleaning mixture at intervals of 5 to 25 minutes, particularly 10 to 15 minutes, based on ethanol purity and silica concentration.
21. The process as claimed in claim 15, further comprising maintaining, in the rectification section, an ethanol purity of 95.5 mole% ethanol by operating at a temperature range of 78°C to 82°C.
22. The process as claimed in claim 15, further comprising operating the stripping section at a temperature range of 78°C to 85°C to separate ethanol from undesired components.
23. The process as claimed in claim 15, further comprising controlling, by an actuated valve synchronized with the spray nozzle system, the flow of lignin-laden slurry through a drain outlet pipe.
24. The process as claimed in claim 15, further comprising collecting the lignin sludge in a settling tank, where it is stored for 15 minutes to 4 hours before further processing.
25. The process as claimed in claim 15, further comprising separating, by a centrifuge, residual sludge from the lignin sludge and recycling the clarified liquid back to the heat exchanger.
26. The process as claimed in claim 15, further comprising dynamically controlling the liquid curtain formed by the donut tray to adjust the flow rate based on real-time silica concentration in the ethanol broth.
27. The process as claimed in claim 15, wherein the feed tray is designed with downward V-notches to handle a feed composition comprising 21% to 25% lignin by weight.
28. The process as claimed in claim 15, further comprising monitoring, by an automated controller, clogging levels of the sieve trays and feed trays, and adjusting the spray nozzle activation accordingly.
29. The process as claimed in claim 15, wherein the cleaning mixture comprises an equimolar mixture of methanol and acetic acid injected by the spray nozzle system comprises 3% to 6% methanol and 3% to 6% acetic acid by volume.
30. The process as claimed in claim 15, wherein the wherein the cleaning mixture comprises non equimolar mixture of methanol and acetic acid injected by the spray nozzle system.