Description:TECHNICAL FIELD
[0001] The present disclosure relates to ethanol production plants. More specifically, the present disclosure pertains to an apparatus and a method for producing ethanol with a biomass slurry and ethanol broth having low to moderate lignin content.

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. Lignin's presence in biomass, as the second most abundant component after cellulose, plays a pivotal role in the economics of biofuels. 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] 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] Conversely, biomass with low to moderate lignin content presents a unique challenge in optimizing the conversion process to achieve high yields of ethanol while minimizing operational costs and maximizing process efficiency. Current processes for producing ethanol from biomass are not fully optimized for biomass slurries and ethanol broths with low to moderate lignin content. Furthermore, existing apparatuses used in the production of ethanol from biomass are often designed for higher lignin content and fail to take full advantage of low to moderate lignin content to streamline the production process. As a result, such apparatuses often lack the efficiency and cost-effectiveness needed for large-scale commercial ethanol production using biomass having low to moderate lignin content.
[0006] 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 vapour and liquid to interact, promoting the separation of components based on their boiling points. However, the accumulation of lignin sludge 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.
[0007] Conventional techniques for dealing with lignin accumulation often involve labour-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 labour 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.
[0008] 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 that contain low to moderate lignin content. The present invention addresses these challenges by providing an apparatus and method for the efficient production of ethanol from biomass slurries and ethanol broths with low to moderate lignin content. 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
[0009] An object of the present disclosure is to provide an apparatus that efficiently processes biomass slurries and ethanol broths, particularly those with low to moderate lignin content, to produce high yields of ethanol.
[0010] Another object of the present disclosure is to provide an apparatus and method for the production of ethanol by effectively breaking down a biomass slurry and ethanol broth without the need for excessive energy or harsh chemicals. The method is adaptable to varying biomass slurries and ethanol broths with low to moderate lignin content, ensuring consistent ethanol production.
[0011] 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 method more economically viable and competitive in large-scale commercial bioethanol production.
[0012] Another object of the present disclosure is to provide an environmentally sustainable solution for bioethanol production. The apparatus promotes an environmentally friendly method for ethanol production by reducing the need for harsh 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.
[0013] Another object of the present disclosure is to provide a flexible apparatus that can adapt to varying biomass feedstocks with low to 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.
[0014] Another object of the present disclosure is to improve the scalability and efficiency of bioethanol production. The apparatus and corresponding method 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.

SUMMARY
[0015] Aspects of the present disclosure relate to an apparatus and a method for producing ethanol from biomass slurries and ethanol broths, particularly those with low to moderate lignin content. The apparatus and method are designed to efficiently break down biomass slurries and ethanol broths by minimizing the challenges posed by lignin, a complex polymer. The apparatus enables the effective pre-treatment of biomass slurries and ethanol broths having low to moderate lignin content without requiring excessive energy, harsh chemicals, or complex procedures.
[0016] In an aspect, the present disclosure discloses an apparatus for producing ethanol with a biomass slurry and ethanol broth having low or moderate lignin content. The apparatus includes a distillation unit configured to receive and process the biomass slurry and ethanol broth to reduce lignin content thereof. The distillation unit includes a heat exchanger/reboiler 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 first 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.
[0017] The distillation unit includes at least one feed tray positioned downstream of the at least one sieve tray. The at least one feed tray includes a plurality of berl saddle to segregate lignin sludge from the biomass slurry and ethanol broth, and a second set of spray nozzles configured to spray a second cleaning mixture over the at least one feed tray to prevent clogging of the lignin sludge present in the biomass slurry and ethanol broth received by the at least one feed tray, and enable collection of the lignin sludge into a sump of the at least one feed tray. The at least one feed tray also includes a plurality of risers configured to allow the vapour generated by the heat exchanger/reboiler to escape therethrough in the vertically upward direction.
[0018] According to an embodiment, the first 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.
[0019] According to an embodiment, each nozzle in the first and second sets of spray nozzles may be configured to rotate dynamically, controlled by the fluid-dynamic pressure generated by the inertial force exerted by the ejected liquid on a freely hinged mechanical portion of the nozzle. This use of inherent fluid momentum reduces the exponential need for actuation devices. The nozzles may also be equipped with timer-controlled devices to precisely remove leftover lignin content, as lignin loading is high in ethanol broth.
[0020] 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.
[0021] 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.
[0022] 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 non-equimolar mixture of acetic acid and methanol.
[0023] 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.
[0024] According to an embodiment, the biomass slurry and ethanol broth may contain about 15-20% weight/weight (w/w) lignin sludge. According to another embodiment, the biomass slurry and ethanol broth may contain about 9-14% w/w lignin sludge. According to another embodiment, the biomass slurry and ethanol broth may contain about 5-8% w/w lignin sludge.
[0025] 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.
[0026] 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.
[0027] 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.
[0028] 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/reboiler to generate the vapour.
[0029] 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.
[0030] According to an embodiment, the distillation unit may include an outlet nozzle configured to extract purified ethanol from the biomass slurry and ethanol broth.
[0031] According to an embodiment, the plurality of berl saddle 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.
[0032] According to an embodiment, the at least one feed tray may include a first feed tray having an arrangement of the plurality of berl saddle, the second set of spray nozzles and the plurality of risers in a first configuration, and a second feed tray having an arrangement of the plurality of berl saddle, the second set of spray nozzles and the plurality of risers in a second configuration different from the first configuration. The first feed tray and the second feed tray may be arranged in a staggered manner relative to one another along the height of the distillation unit.
[0033] According to an embodiment, the at least one sieve tray may include a first weir/downcomer 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/downcomer.
[0034] According to an embodiment, the at least one feed tray may include a second weir/downcomer 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/downcomer.
[0035] According to another aspect of the present disclosure, a method for producing ethanol with a biomass slurry and ethanol broth having low or moderate lignin content is disclosed. The method includes receiving, by a feed entry nozzle of a distillation unit, the biomass slurry and ethanol broth at a pre-defined rate. The method includes boiling, by a heat exchanger/reboiler, a liquid at a bottom of the distillation unit to generate vapour traversing in a vertically upward direction 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 method also includes segregating, by a plurality of berl saddle of at least one feed tray positioned downstream of the at least one sieve tray, lignin sludge from the biomass slurry and ethanol broth, and allowing, by a plurality of risers of the at least one feed tray, the vapour generated by the heat exchanger/reboiler to escape therethrough in the vertically upward direction.
[0036] The method 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.
[0037] 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.
[0038] According to an 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 at least 9-14% w/w lignin sludge. According to another embodiment, the biomass slurry and ethanol broth may contain at least 5-8% w/w lignin sludge.
[0039] According to an embodiment, the method 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 method may further include supplying a liquid output from the centrifuge to the heat exchanger/reboiler to generate the vapour.
[0040] According to an embodiment, the method may include extracting, by an outlet nozzle of the distillation unit, purified ethanol from the biomass slurry and ethanol broth.
[0041] According to an embodiment, the method 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 method 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.
[0042] According to an embodiment, the method may include regulating, by a first weir/downcomer 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/downcomer. The method may further include regulating, by a second weir/downcomer 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/downcomer.
[0043] 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
[0044] 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.
[0045] FIG. 1 illustrates an exemplary schematic representation of an apparatus for producing ethanol with a biomass slurry and ethanol broth having low to moderate lignin content, in accordance with an embodiment of the present disclosure;
[0046] FIG. 2 shows an exemplary representation of an arrangement of multiple feed trays along a height of a distillation unit of the apparatus, in accordance with an embodiment of the present disclosure;
[0047] FIG. 3 shows an exemplary representation of a nozzle provided on a sieve tray to spray a first cleaning mixture over the sieve tray, in accordance with an embodiment of the present disclosure; and
[0048] FIG. 4 illustrates an exemplary flow chart representation of a method for producing ethanol with a biomass slurry and ethanol broth having low to moderate lignin content, in accordance with an embodiment of the present disclosure.

DETAILED DESCRIPTION
[0049] 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.
[0050] The present invention provides a solution to a spectrum of engineering challenges in distillation columns/towers used for bio-ethanol distillation, with feedstock having low to moderate lignin content. In addition to ethanol, acetic acid, fusel oil, and technical oil 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 at 15.6/15.6°C minimum (excluding denaturant), a relative density of 0.7961 (max), and a flashpoint of 16.6°C. 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.
[0051] For brevity, due to the presence of 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 sugarcane bagasse and cotton stalks, 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 low to 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 method for efficiently managing ethanol broth with a lignin-laden stillage.
[0052] Embodiments described herein relate to an apparatus and method for efficiently processing biomass slurries and ethanol broths with low to moderate 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 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.
[0053] FIG. 1 illustrates an exemplary schematic representation of an apparatus 100 for producing ethanol with a biomass slurry and ethanol broth having low to moderate 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 wheat straw, stalks and pods, rice husk, millet (bajra, jowar, ragi) stalks, soybean stalks, and mustard waste, which contain about 15-20% weight/weight (w/w) lignin sludge. In one embodiment, the biomass slurry and ethanol broth may include groundnut stalks, tea pruning wastes, coffee husk and pruning wastes, rubber (primary and secondary) waste, and corn cob, which contain about 9-14% w/w lignin sludge. In another embodiment, the biomass slurry and ethanol broth may include napier grass, sugarcane toppings, root starch, Empty Fruit Bunches (EFB), and banana residue, which contain about 5-8% w/w lignin sludge.
[0054] The distillation tower 102 includes a feed entry nozzle 104 that receives the biomass slurry and ethanol broth containing the 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/reboiler 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. The sieve tray 108 includes a plurality of perforations 110 to enable passage for the vapour generated by the heat exchanger/reboiler 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/downcomer 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/downcomer.
[0055] The distillation tower 102 also includes one or more feed trays 114-1, 114-2, … 114-N (also referred to as “feed tray 114” herein) 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.
[0056] 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 116 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 116, 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.
[0057] 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.
[0058] 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.
[0059] 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.
[0060] 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.
[0061] Referring now to FIG. 2, each feed tray 114 includes a plurality of berl saddle 202 to segregate lignin sludge from the biomass slurry and ethanol broth when the biomass slurry and ethanol broth passes over the feed tray 114. Each berl saddle 202 may be shaped like a saddle, with both internal and external surfaces entirely openstructure made from materials like metal, plastic, or ceramic. The berl saddle 202 may include multiple openings or slots around its surface, which provide a large surface area for contact between the two phases, i.e., liquid and vapour, promoting efficient mass transfer and fluid flow. The berl saddle 202 minimize the number of contours and crevices that cause flow of the biomass slurry and ethanol broth to be held up, and assist segregation of the lignin sludge present in the biomass slurry and ethanol broth.
[0062] The feed tray 114 also includes a second set of spray nozzles 204 configured to spray a second cleaning mixture over the feed tray 114 to prevent clogging of the lignin sludge present in the biomass slurry and ethanol broth received by the feed tray 114. The berl saddle 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 second set of spray nozzles 204 may dispense the second cleaning mixture over the feed tray 114 to enable collection of the stagnated lignin sludge into a sump 206 of the feed tray 114. Each feed tray 114 may also include a plurality of risers or chimneys 208 that allow the vapour generated by the heat exchanger/reboiler 106 to escape therethrough in the vertically upward direction, and facilitate liquid-gas interaction between the biomass slurry and ethanol broth and the vapour. The second set of spray nozzles 204 may be timer-controlled to dispense the second cleaning mixture over the feed tray 114 in pre-defined time intervals of 5 to 25 minutes, for example. In an exemplary embodiment, each feed tray 114 may include 1 to 20 spray nozzles 204 to direct the second cleaning mixture in the opposite direction to the fractionation flow of the biomass slurry and ethanol broth over the feed tray 114. The second cleaning mixture may contain an non-equimolar mixture of acetic acid and methanol.
[0063] The first and second sets of spray nozzles 112, 204 may be configured to flush the cleaning mixtures over the corresponding sieve tray 108 or the feed tray 114 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 feed tray 114 within the distillation tower 102. Referring now to FIG. 3, each nozzle of the first set of spray nozzles 112 may be configured to rotate dynamically, and be controlled by the fluid-dynamic pressure generated by the inertial force exerted by the ejected liquid on a freely hinged mechanical portion/component of the corresponding nozzle 112. This use of inherent fluid momentum reduces the exponential need for actuation devices. The nozzles may also be equipped with timer-controlled devices to precisely remove leftover lignin content, as lignin loading is high in ethanol broth. The second set of spray nozzles 204 may have a similar configuration as the first set of spray nozzles 112.
[0064] The berl saddle 202 may be arranged over the feed tray 114 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 feed tray 114, and gets collected within a sump 206 of the feed tray 114.
[0065] In an exemplary embodiment, the feed trays 114 may include at least first feed tray 114-1 having an arrangement of the berl saddle 202, the second set of spray nozzles 204 and the chimneys 208 in a first configuration, a second feed tray 114-2 having an arrangement of the berl saddle 202, the second set of spray nozzles 204 and the chimneys 208 in a second configuration different from the first configuration, and a third feed tray 114-3 having an arrangement of the berl saddle 202, the second set of spray nozzles 204 and the chimneys 208 in a third configuration that is different from the first and second configurations. The first, second and third feed trays 114-1, 114-2 and 114-3 may be arranged in a staggered manner relative to one another along the height of the distillation tower 102, as depicted in FIG. 2.
[0066] 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 (non-equimolar 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 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. The controller may also be configured to actuate the first and second sets of spray nozzles 112, 204 in response to ethanol specification disturbances caused by the clogging/choking of the sieve trays 108 and the feed trays 114.
[0067] In an exemplary embodiment, the controller is configured to manage the first and second sets of spray nozzles 112, 204 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.
[0068] 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.
[0069] The sieve trays 108 and the feed trays 114 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 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 in a sequential manner.
[0070] 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 feed trays 114. 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.
[0071] Each of the feed trays 114 may include a drain outlet pipe 210, as shown in FIG. 2, positioned at the sump 206 to facilitate removal of the collected lignin 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 may include a second weir/downcomer 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/downcomer 212, while the lignin sludge gets collected in the sump 206 of the feed tray 114.
[0072] 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 second set of spray nozzles 204 is activated, the valve is simultaneously triggered to open the drain outlet pipe 210. This allows the washed liquid 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, 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.
[0073] 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.
[0074] In an exemplary embodiment, the lignin-laden biomass slurry and ethanol broth that escapes from the last tray 108/114 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, 114, free from lignin lumps and nucleation-assisted lignin agglomerates.
[0075] FIG. 4 illustrates an exemplary flow chart representation of a method 400 for producing ethanol with a biomass slurry and ethanol broth having low to moderate lignin content. The method 400 is performed by the apparatus 100 depicted in FIG. 1. The biomass slurry and ethanol broth may contain at least 15-20% w/w lignin sludge. In an embodiment, the biomass slurry and ethanol broth may contain at least 9-14% w/w lignin sludge. In another embodiment, the biomass slurry and ethanol broth may contain at least 5-8% w/w lignin sludge.
[0076] The method 400 includes a step 402 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 method 400 also includes, at step 404, boiling, by the heat exchanger/reboiler 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, and, at step 406, supplying the biomass slurry and ethanol broth to the at least one sieve tray 108 having the perforations 110 to enable passage for the vapour to pass therethrough. The method 400 also includes a step 408 of segregating, by berl saddle 202 of the at least one feed tray 114 positioned downstream of the at least one sieve tray 108, lignin sludge from the biomass slurry and ethanol broth, and a step 410 of allowing, by the chimneys 208 of the at least one feed tray 114, the vapour generated by the heat exchanger/reboiler 106 to escape therethrough in the vertically upward direction.
[0077] The method 400 further includes a step 412 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 412 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 method 400 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 method 400 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.
[0078] The method 400 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 method 400 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 method 400 may also include supplying a liquid output from the centrifuge 140 to the heat exchanger/reboiler 106 to facilitate generation of the vapour. The method 400 may include extracting, by the outlet nozzle 120 of the distillation tower 102, purified ethanol from the biomass slurry and ethanol broth.
[0079] The method 400 may include regulating, by the first weir/downcomers 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 weir/downcomers. The method 400 may further include regulating, by the second weir/downcomers 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 weir/downcomers 212.
[0080] With the apparatus 100 and the method 400 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.
[0081] Thus, the apparatus 100 and the method 400 of the present disclosure enable the efficient processing of biomass slurries and ethanol broths with low to moderate lignin content to produce high yields of ethanol. By reducing lignin-related barriers, the method 400 enhances enzymatic hydrolysis and fermentation efficiency, leading to improved ethanol production. The apparatus 100 and the method 400 minimize the need for excessive energy input& harsh chemicalsthereby reducing environmental impact and operational costs compared to conventional ethanol production techniques.
[0082] While the foregoing describes various embodiments of the invention, other and further embodiments of the invention may be devised without departing from the basic scope thereof. The scope of the invention is determined by the claims that follow. The invention is not limited to the described embodiments, versions or examples, which are included to enable a person having ordinary skill in the art to make and use the invention when combined with information and knowledge available to the person having ordinary skill in the art.

ADVANTAGES OF THE PRESENT DISCLOSURE
[0083] The present disclosure provides an apparatus and a method for efficiently processing biomass slurries and ethanol broths with low to moderate lignin content, enabling high yields of ethanol by novel distillation column comprising trays equipped with berl saddles, and risers.
[0084] The present disclosure provides a method 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 methods.
[0085] The present disclosure provides an apparatus and method for the production of ethanol while reducing energy consumption and chemical use. This makes the apparatus economically viable and competitive for large-scale commercial ethanol production.
[0086] The present disclosure provides a method 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 method eco-friendly.
[0087] The present disclosure provides an apparatus designed to be adaptable to a wide range of biomass feedstocks with low to 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.
[0088] The present disclosure provides an apparatus and method 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.
, Claims:1. An apparatus (100) for producing ethanol with a biomass slurry and ethanol broth having low or moderate lignin content, comprising:
a distillation unit (102) configured to receive and process the biomass slurry and ethanol broth to reduce lignin content thereof, the distillation unit (102) comprising:
a reboiler (106) configured to boil a liquid at a bottom of the distillation unit (102) to generate vapour traversing in a vertically upward direction within the distillation unit (102);
at least one sieve tray (108) having a plurality of perforations (110) to enable passage for the vapour to pass therethrough, and a first set of spray nozzles (112) configured to spray a first cleaning mixture over the at least one sieve tray (108) to prevent clogging of lignin sludge present in the biomass slurry and ethanol broth received by the at least one sieve tray (108), and
at least one feed tray (114) positioned downstream of the at least one sieve tray (108), the at least one feed tray (114) comprising:
a plurality of berl saddle (202) to segregate lignin sludge from the biomass slurry and ethanol broth;
a second set of spray nozzles (204) configured to spray a second cleaning mixture over the at least one feed tray (114) to prevent clogging of the lignin sludge present in the biomass slurry and ethanol broth received by the at least one feed tray (114), and enable collection of the lignin sludge into a sump (206) of the at least one feed tray (114); and
a plurality of risers (208) configured to allow the vapour generated by the reboiler (106) to escape therethrough in the vertically upward direction.

2. The apparatus (100) as claimed in claim 1, wherein the first set of spray nozzles (112) are timer-controlled to dispense the first cleaning mixture over the at least one sieve tray (108) in pre-defined time intervals.

3. The apparatus (100) as claimed in claim 1, wherein the second set of spray nozzles (204) are timer-controlled to dispense the second cleaning mixture over the at least one feed tray (114) in pre-defined time intervals.

4. The apparatus (100) as claimed in claim 3, wherein the distillation unit (102) comprises a controller configured to:
monitor clogging of the lignin sludge received by any of the at least one sieve tray (108) and the at least one feed tray (114); and
control 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.

5. The apparatus (100) as claimed in claim 1, wherein the first cleaning mixture comprises equimolar mixture of acetic acid and methanol.

6. The apparatus (100) as claimed in claim 1, wherein the second cleaning mixture comprises non-equimolar mixture of acetic acid and methanol.

7. The apparatus (100) as claimed in claim 6, further comprising a ratio controller (126) configured to control the equimolar mixture of methanol and acetic acid in a ratio of about 3% to 6% by volume.

8. The apparatus (100) as claimed in claim 1, wherein the biomass slurry and ethanol broth contains about 15-20% w/w lignin sludge.

9. The apparatus (100) as claimed in claim 1, wherein the biomass slurry and ethanol broth contains about 9-14% w/w lignin sludge.

10. The apparatus (100) as claimed in claim 1, wherein the biomass slurry and ethanol broth contains about 5-8% w/w lignin sludge.

11. The apparatus (100) as claimed in claim 1, wherein the at least one sieve tray (108) and the at least one feed tray (114) are arranged in a staggered manner relative to one another along a height of the distillation unit (102).

12. The apparatus (100) as claimed in claim 1, wherein the distillation unit (102) comprises a feed entry nozzle (104) configured to supply the biomass slurry and ethanol broth to any of the at least one sieve tray (108) and the at least one feed tray (114) at a pre-defined rate.

13. The apparatus (100) as claimed in claim 1, wherein the distillation unit (102) comprises one or more settling tanks (136, 138) configured to receive the lignin sludge collected in the sump (206) of the at least one feed tray (114).

14. The apparatus (100) as claimed in claim 13, wherein the distillation unit (102) comprises a centrifuge (140) configured to separate residual sludge from the lignin sludge received by the one or more settling tanks (136, 138), and wherein a liquid output from the centrifuge (140) is supplied to the reboiler (106) to generate the vapour.

15. The apparatus (100) as claimed in claim 13, wherein the at least one feed tray (114) comprises a drain outlet pipe (210) positioned at the sump (206) to facilitate removal of the collected lignin sludge, the drain outlet pipe (210) being controlled by a valve synchronized with the second set of spray nozzles (204) to optimize transfer of the collected lignin sludge to the one or more settling tanks (136, 138).

16. The apparatus (100) as claimed in claim 1, wherein each spray nozzle of the first set of spray nozzles (112) and the second set of spray nozzles (204) are configured to rotate dynamically, and be controlled by fluid-dynamic pressure generated by inertial force exerted by an ejected liquid on to a freely hinged mechanical portion of the corresponding nozzle.

17. The apparatus (100) as claimed in claim 1, wherein the distillation unit (102) comprises an outlet nozzle (120) configured to extract purified ethanol from the biomass slurry and ethanol broth.

18. The apparatus (100) as claimed in claim 1, wherein the plurality of berl saddle (202) are arranged on the at least one feed tray (114) in a random packing arrangement to facilitate collection of the lignin sludge into the sump (206).

19. The apparatus (100) as claimed in claim 1, wherein the at least one feed tray (114) comprises:
a first feed tray (114-1) having an arrangement of the plurality of berl saddle (202), the second set of spray nozzles (204) and the plurality of risers (208) in a first configuration; and
a second feed tray (114-2) having an arrangement of the plurality of berl saddle (202), the second set of spray nozzles (204) and the plurality of risers (208) in a second configuration different from the first configuration, wherein
the first feed tray (114-1) and the second feed tray (114-2) are arranged in a staggered manner relative to one another along the height of the distillation unit (102).

20. The apparatus (100) as claimed in claim 1, wherein the at least one sieve tray (108) comprises a first weir or downcomer 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 or downcomer.

21. The apparatus (100) as claimed in claim 1, wherein the at least one feed tray (114) comprises a second weir or downcomer (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 or downcomer (212).

22. A method (400) for producing ethanol with a biomass slurry and ethanol broth having low or moderate lignin content, comprising the steps of:
receiving, by a feed entry nozzle (104) of a distillation unit (102), the biomass slurry and ethanol broth at a pre-defined rate;
boiling, by a reboiler (106), a liquid at a bottom of the distillation unit (102) to generate vapour traversing in a vertically upward direction within the distillation unit (102);
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;
segregating, by a plurality of berl saddle (202) of at least one feed tray (114) positioned downstream of the at least one sieve tray (108), lignin sludge from the biomass slurry and ethanol broth;
allowing, by a plurality of risers (208) of the at least one feed tray (114), the vapour generated by the heat exchanger/reboiler (106) to escape therethrough in the vertically upward direction;
regulating, by a controller, actuation of a first set of spray nozzles (112) to control dispensing of a first cleaning mixture over the at least one sieve tray (108) to prevent clogging of the biomass slurry and ethanol broth received by the at least one sieve tray (108), and actuation of a second set of spray nozzles (204) to control dispensing of a second cleaning mixture over the at least one feed tray (114) to enable collection of the lignin sludge into a sump (206) of the at least one feed tray (114).

23. The method (400) as claimed in claim 22, where the step of regulating comprises controlling actuation of the first set of spray nozzles (112) and the second set of spray nozzles (204) based on pre-determined washing cycles.

24. The method (400) as claimed in claim 22, wherein the biomass slurry and ethanol broth contains at least 15-20% w/w lignin sludge.

25. The method (400) as claimed in claim 22, wherein the biomass slurry and ethanol broth contains at least 9-14% w/w lignin sludge.

26. The method (400) as claimed in claim 22, wherein the biomass slurry and ethanol broth contains at least 5-8% w/w lignin sludge.

27. The method (400) as claimed in claim 22, further comprising:
supplying the lignin sludge collected in the sump (206) to one or more settling tanks (136, 138); and
separating, by a centrifuge (140) of the distillation unit (102), residual sludge from the lignin sludge received by the one or more settling tanks (136, 138); and
supplying a liquid output from the centrifuge (140) to the reboiler (106) to generate the vapour.

28. The method (400) as claimed in claim 22, further comprising extracting, by an outlet nozzle (120) of the distillation unit (102), purified ethanol from the biomass slurry and ethanol broth.

29. The method (400) as claimed in claim 22, further comprising:
monitoring, by a controller, clogging of the lignin sludge received by any of the at least one sieve tray (108) and the at least one feed tray (114); and
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.

30. The method (400) as claimed in claim 22, further comprising:
regulating, by a first weir or downcomer of the at least one sieve tray (108), 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 or downcomer; and
regulating, by a second weir or downcomer (212) of the at least one feed tray (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 weir or downcomer (212).